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V - E-Library - WMO

0/ //,/ Cl,)NOTEThe designations employed and the presentation of the material in this publication do notimply the expression of any opinion whatsoever on the part of the Secretariat of the WorIdMeteorological Organization concerning the legal status of any country or territory or of itsauthorities, or concerning the delimitation of its frontiers.© 1971, World Meteorological OrganizationInternational Council of Scientific Unions

FOR E W0 R DThis publication, the fourth in the series of GARP Special Reports,contains the report of the first session of the Tropical Experiment Board of theGARP Atlantic Tropical Experiment, held in Geneva from 22 to 24 February 1971.Invitations were sent out by the Secretary-General of WMO on behalf of WMO andICSU.The Tropical Experiment Board was established by WMO and ICSU. Itsmembers are the officially designated representatives of the Member governmentswhich have signified their intention of contributing substantially to the GARPAtlantic Tropical Experiment and the representatives of Regional Associations I,III and IV. The Board's functions are to act as the central international bodyfor the planning and implementation of the Atlantic Tropical Experiment.Apart from a few minor editorial changes, the report contained hereinis in the form approved by the Tropical Experiment Board. The findings andrecommendations it contains will be considered in due course by competent bodiesof WMO and lCSU. Action has already been taken on certain of the more urgentinterim measures proposed.I wish to express my admiration for the teamwork, dedication anddispatch with which the Tropical Experiment Board began its task of formulatingplans for the organization and implementation of the Experiment. The auspiciousbeginning reflected in this report augurs well for the future of the GARP TropicalAtlantic Experiment.~.. .Secretary-General, WMO

CON TEN T S1. ORGANIZATION OF THE SESSION1.1 Opening of the session1.2 Election of chairman1.3 Approval of the agenda1.4 Working arrangements112222. APPROVAL OF THE REGULATIONS OF THE TEB . . . . . . . . .. . . . .. . 33.REVIEW OF THE REPORT OF THE FIRST SESSION OF THE TEC64. PRESENTATION OF THE SCIENTIFIC PLAN FOR THE TROPICAL EXPERIMENT4.1 JOC recommendations •• • •4.2 Additional considerations4.6 TEB decisions •• • • • • •· · · ·7· · · ·7· · · ·9105.PRESENTATION AND REVIEW OF PROGRESS OF THE WORK OFTHE CONSULTANTS •••••••••••••••••126.DIRECTIVES FOR THE FUTURE WORK OF THE SCIENTIFIC ANDMANAGEMENT GROUP (SMG) ••••••••••••••137.THE ORGANIZATION, OPERATION AND ESTABLISHMENT OF THE SMG157.1The need for an SMG• • •157.2 The need for international financial support 167.3 Location of the SMG • • • 17

2REPORT OF THE SESSION1.2Election of chairman1.2.1 Dr. B.J. Mason, the principal delegate of the United Kingdom, wasunanimously elected to serve as chairman of the Tropical Experiment Board forthe duration of the session and up to the next session of the Board.1.2.2 Dr. Mason thanked the Board for their expression of confidence andspoke of the magnitude of the task facing those responsible for the planning ofGATE. In his view GATE was an experiment of a scale and complexity neverattempted before as an international undertaking. This unprecedented challengemust be matched by thought and effort of exceptional quality, determination andcourage. Dr. Mason referred to the often expressed fact that meteorology wasbasically of an international character with nations working closely togetherfor the common good; he considered that GATE would provide an excellnnt opportunityto put this to the test. The success of GATE depended not only on the individualnational contributions but also on the way in which these would be mergedinto a combined and integrated effort. The planning and execution of GATE wouldraise new problems and Dr. Mason considered that the Board should not be afraidof creating precedents in order to solve these problems.1.3Approval of the agendaThe approved agenda is reproduced in Annex 11.1.4Working arrangementsAll the items on the agenda were discussed first in plenary meetings.An ad hoc group was set up under the chairmanship of Professor B. Bolin to preparea report for plenary on item 6; a small group under Mr. A. Silva de Sousa wasalso set up under item 7 to draft the terms of reference of the Scientific andManagement Group.

t-REPORT OF THE SESSION 5BelgiumCanadaFederal Republic of GermanyFrancePortugalU.S.S.R.United KingdomU.S.A.It was further agreed that at each session the Board would consider whether anyadditional Member governments should be invited to be represented on TEB 1naccordance with the regulation providin~ for such invitations to be issued toMember governments whose participation on the TEB is considered to be importantfor the success of GATE. The chairman of TEB-was authorized to keep this matterunder review between sessions of the Board and to take action on its behalf asnecessary. It was decided that although Japan was not represented at this firstsession of TEB, the invitation should be renewed in the hope that Japan would berepresented at the next regular session of TEB.2.11 The representative of IOC expressed the appreciation of his organizationfor having been invited to be represented at the first session of TEB. Hestated thatIOC would like to have close ties with TEB and noted with satisfactionthat the TEB regulations included provision for IOC to be invited to berepresented at all sessions of the Board.

8 REPORT OF THE SESSIONspecial emphasis must be placed on the sub-cloud layer, which will requireadditional instrumentation (e.g., tethered balloons) over and above thenormal rawinsonde. The sub-cloud layer observing system must have the capabilityto make observations in disturbed weather~ In order to monitor theliquid water content of and precipitation from convective elements duringtheir life cycles, calibrated radar should be used. Ideally, this could bedone by viewing the area with a satellite-borne radar, but in practice itmay have to be done from the ships, as many of which as possible should beequipped with suitable radar. Further, detailed observations of the surfacelayer must be made; in addition to the normal synoptic observations (temperature,humidity and pressure to 0.1 mb), the sea-surface temperature,radiation budget, and the sea state should be observed. Radiation measurementsby aircraft should also be made, especially over the tops of activeconvective systems.(d)Adequate observations on the scale of the convective ensembles (C and Dscales) in order to sample their internal structure. Instrumented aircraftare the key observing tools for this scale. It is clear from the informationcurrently available that the number of such aircraft envisioned willbe insufficient to accomplish the full objectives. Additional aircraftsuitably instrumented need to be obtained, unless means can be found toincrease the effectiveness of those currently pledged by the countries.(e) The radiation budget at the top of the atmosphere, as determined by satelliteobservations.4.1.7 JOC also recommends the following additional observations as highly desirablefor GATE:(a) Infrared temperature soundings, at least on an experimental basis, from ageostationary satellite, to sig~ificantly augment the aircraft observationsby supplying unique data, nearly continuous in time, that would, for example,delineate temperature anomalies associated with the wave-scale as well asthe meso-convective scale phenomena.(b)Supplementary observations from other observing systems (e.g., researchsatellites) or from relevant experiments or development tests that may becarried out in the time frame of the GATE. Among such possibilities werementioned winds from superpressure balloons experiments, wind profiles fromtests of carrier balloon-Onegasonde systems, or high resolution stereophotography from manned space flight missions.4.1.8 Some real time, or quasi..real time, processing of data, especially on theA-scale but including selected B-scale data are required for efficient operationalplanning on a day-to-day basis, as well as for providing a quick-look capabilityfor the various data fields to identify an~ problems that may be necessary to correctfor in the final processing effort.

REPORT OF THESESSION94.1.9 Because of the magnitude of the effort and the heterogeneity of the observit~system for GATE, JOC recommends that a trial observation period using representativeobserving sub-systems be carried out in the year preceCling the GATE.4.1.10 JOC requests TEBjSMG, in accordance with the proposed regulations, to establisheasy and quick communication mechanisms with JOC, via the JPS, so that JOC canfulfil its obligations to keep.·~nder review the planning so as to assure that thescientific objectives will be met. For its part, JOC has authorized three of itsmembers to act individually, as appropriate, on behalf of JOC in responding to anyquery from TEBjSMG with regard to any matter that may come up in planning that mightjeopardize the meeting of the scientific objectives, or that may on the other handimprove the scientific possibilities of the GATE.4.2 Additional considerationsThe scientific objectives of the tropical experiment were restated in Bombayin the context of the general objectives of GARP, and provide a frame of referencefor discussing the scientific plan of the experiment which is reflected in the JOCrecommendations above.4.3 GARP, as has been discussed in JOCdocuments, is directed toward understandingthe general circulation of the entire atmosphere and its variability, principallythrough the simulation in numerical models of the behaviour of the atmosphere.At the moment, middle and higher ktitudes are treated more realistically in suchmodels than are the tropics, largely owing to an inadequate level of understandingof tropical dynamical processes, which are usually manifest on scales comparablewith or smaller than practical observational or computational grid sizes. In addition,there is a serious lack of quantitative data in the tropics with which to testthe validity of models. It is clear, then, that if the goals of GARP are to be met,the important dynamical processes in the tropics must be accounted for adequately inthe numerical models. Consequently the GARP Atlantic Tropical Experiment has beendesigned t~ provide (i) an observational basis upon which to develop appropriatenumerical parameterization schemes for estimating the effects of the smaller tropicalweather systems on the larger scale circulations and (ii) comprehensive data againstwhich the validity of numerical prediction methods can be tested in the tropics.4.4 During the discussion of the general aspects ~f the objectives, and how totranslate them into a project plan, it became clear that the eastern Atlantic affordsan excellent opportunity to observe the fundamental tropical disturbances of interestand that the highest priority for planning should focus there. The JOC recommendedthe area approximately SON to 15°N, 23 0 W to 30oW.4.5 It was pointed out by Professor Bolin that preliminary information on theplans for GATE had been conveyed to the oceanographic community at their recent internationalcongress. Moreover, in conjunction with the discussions on the need forsub-cloud layer observations in GATE, it was emphasized that the participation ofoceanographers was highly desirable. The representative of the IOC, AdmiralLangeraar, confirmed the interest of the oceanographic community in GATE and mentionedthe desirability of an oceanographer to participate in the work of the SMG.

10REPORT OF THE.SESSION4.6. TEB decisions4.6.1 The Tropical Experiment Board, af~er reviewing the JOG recommendations relatingto the GATE:(i)(ii)Reaffirmed the great potential of the proposed experiment;Accepted the scientific objectives as defined by the JOG;(iii) Adopted provisionally the time period of June, July, August 1974for the experiment;(iv)(v)(vi)(vii)(viii)(ix)Adopted for the experiment the area between lOoS and 20 0 N and between90 0 Wand 40 0 E, as recommended by JOG and TEC;Accepted the B-scale area of the eastern Atlantic as providing themost favourable concentration of convective phenomena to be studiedintensively;Agreed to focus the detailed planning of the experiment on theB-scale area specified, but recognized that questions concerningthe availibility of essential platforms, base facilities andlogistics might have a significant influence on the choice of thisarea, and urged that these be studied further;Acknowledged the importance of providing the observing capability+equired as recommended by the JOC for the full success of the experimentand stressed the need for a complete examination of thepracticability of obtaining these types of observations;Supported the need for a certain amount of real-time data-processingat least for day-to-day operational planning and quality control asexpress~d in the JOC recommendation;Recommended that IOC should be invited to arrange if possible foran oceanographer to participate in the planning activities of the SMG.4.6.2 Under this item, the Board also reviewed the calendar of events and decisionsadopted by the Interim Planning Group on GARP Tropical Experiment meeting in London(see GARP Special Report No. 2, paragraph 3.1). The following revised schedule wasagreed:(a) A preliminary plan for GATE should be completed in time for considerationat the sixth session of JOC (October 1971);(b) The TEB should review the preliminary plan for GATE and the JOGcomments at its next regular session (tentatively, November 1971);

REPORT OF THE SESSION11(c)The date of the Experiment should be confirmed by TEB on thatoccasion;(d) Firm commitments by the nations should be received by March 1972;(e)A further session of TEB should be convened shortly after March1972 to review the commitments.4.6.3 The preliminary plan should contain sufficient detail to enable nationsto decide on the commitment of major observing platforms and base facilities forthe conduct of GATE.

12 REPORT OF THE SESSION5. PRESENTATION AND REVIEW OF PROGRESS OF THE WORK OF THE 'CONSULTANTS5.1 The Interim Scientific Management Group (ISMG), consisting ofconsultants provided by Members, presented a revIew of the work on theplanning of the Tropical Experiment. Specifically, they presented theresults of their studies with respect to a protect development plan,the synoptic background for the Atlantic area and the adjacent continentalareas, the status of and plans for the World Weather Watch stationsand ships and aircraft of opportunity in the area of the Experiment,tentative layouts of ship stations, ship schedules and associatedinstrumental problems and aircraft Reeds. The individual reports ofthe consultants are reproduced in Annexes IV to IX.5.2 The Board noted with great interest the various presentationsand recommendations and commended the consultants on their work. TheBoard expressed the opinion that a very great effort will be requiredto plan this complex experiment properly.5.3 The Board concurred that a significant increase in the number ofresearch aircraft committed to the Experiment would be needed in orderto accomplish the scientific objectives for the C- and D-scales. Itwas noted that further study would be needed in order to establish theexact number of aircraft and their instrumentation required for thispurpose. Further studies should also be undertaken to determine if anyadditional ships will be required in the light of the satellite' dataexpected to be available.

REPORT OF THESESSION136. DIRECTIVES FOR THE FUTURE WORK OF THE SCIENTIFIC AND MANAGEMENTG~WUP (SMG)6.1 The Board considered the various studies which would have to becompleted within the next six to nine months if the agreed time schedulefor the GATE is to be met.6.2 In the first place it would be necessary to work out the detaileddesign of the observational system in such a way that the scientificobjectives of the experiment, on all scales, will be accomplished.doing so, full account should be taken of the work of a similar characterbeing undertaken by the JOC Working Group on Numerical Experimentation,and in particular by its sub-Group 2 "Observing Systems Simulation"and sub-Group 6 "Dynamics of Tropical Motion Systems". It will also benecessary to simulate various observational schemes using, for example,data from previous experiments, enhanced satellite photographs, andpreliminary data from the WWWnetwork in the area. The work might well bedivided according to the three scales to be studied, particularly asdifferent procedures and observational tools will be needed for eachscale.The results of this study will help in determining the numberand types of ships to be used in the A- and B-scales. The Board consideredthat preliminary information is urgently needed with regard to theC-scale.also required.A design and test of a sub-cloud layer observing system isFurther consideration should be given to the availabilityof the necessary observing platforms and base facilities for the B-scaleareas in the east and west Atlantic.6.3 The Board noted the decisions of the Tropical Experiment Councilregarding the need for obtaining detailed information about the facilitieswhich would be made available for the tropical experiment (see GARP SpecialReport No. 3, paragraph 8.6). The Boar9 decided that the SMG shouldcompile a list of observing platforms and base facilities needed for theconduct of GATE and requested the Secretary-General to provide anynecessary assistance in this work and to address individual inquiriesto Members as may be necessary.In6.4 Since upper-wind data are essential to the aims of the experiment,the Board recommended that Members should put urgent effort into thefurther development and trial of upper-wind measuring systems based onnavigation aids and to make the results generally available as soon aspossible.

14 REPORT OF THE SESSION6.5 Studies should also be undertaken on the problem of estimatingrainfall rate from a combination of radar data, enhanced satellite photographsand raingauge records.6.6 Consideration should be given to the need for field tests ofrepresentative components of the observational system including data management.The need for instrumental comparisons and for tests of any newinstrumentation which becomes available should be investigated.6.7 On the basis of the proposals in section 9 of Annex F of thereport of the fourth session of JOC,a data-flow plan should be developedwhich would define the division of responsibility for telecommunicationsand data-processing between national and international groups.It shouldbe clearly specified which data should be collected and analysed in realtimefor the conduct of the experiment itself, for example,for day-todayplanning and monitoring purposes.6.8 The Board recognized that the above work programme would exceedthe capacity of the existing Interim Scientific and Management Group.Further support would therefore have to be provided by one or both of thefollowing methodsa(a)(b)The ISMG should be strengthened by providing the services ofadditional experts, either on a long-term or a short-term basis;Some specific projects should be undertaken .by national groups.6.9 The ISMG was requested to prepare a detailed work programme onthe basis of the above considerations and to determine the magnitude ofthe effort required to execute the programme.Suggestions should alsobe made as to how the work could be best distributed between the ISMGitself and national groups.The ISMG should advise the chairman of TESon the above points as soon as possible and the chairman should thentake appropriate action to initiate the work.6.10 The ISMG was also requested to arrange;as a matter of urgency,ameeting of a group of experts to make recommendations on the capabilitiesand most effective techniques for the us~of instrumented aircraft inconjunction with satellite information.

REPORT OF THESESSION157. THE ORGANIZATION, OPERATION AND ESTABLISHMENT OF THE SMG7.1The need for an SMG7.1.1 The need for a Scientific and Management Group (SMG) was discussedat the GARP Planning Conference in Brussels, at the London session of the InterimPlanning Group on the GARP Tropical Experiment and also at the twenty-secondsession of the WMO Executive Committee. The latter had requested TEB to considerspecifically the location of the SMG and the need for the scientific directorand his deputy to be recruited as international civil servants.7.1.2 The view of most participants was that the concept of the SMG wascentral and vital to the whole GATE project. The consultants constituting theso-called "Interim Scientific and Management Group" had already demonstratedwhat could be achieved in a relatively short time by a small group of expertsworking full time on the planning of GATE. This group had demonstrated above allhow much planning remains to be done. Although much of the GATE planning willbe carried out directly by national authorities as part of their contribution toGATE, there was a clearly defined need for an international group, such as theSMG, to maintain the scientific and technological coherence of all the nationalefforts and to prepare material needed for future sessions of TEB.7.1.3 It was further pointed out by several speakers that continuity inGATE planning work was essential and that this could best be assured by havinga small group of dedicated people serving on SMG for periods of from three tofive years.7.1.4 The delegate of the U.S.S.R. considered however that it would beunreasonable at this stage to recruit any staff for GATE planning on an internationalbasis; he believed that all the outstanding questions relating to GATEcould be settled by existing bodies with the assistance, as required, of invitedexperts.7.1.5 The Board was reminded that the present schedule called for thecompletion of "the detailed scientific design" of GATE by September 1971. Thegeneral view of members was that this could only be achieved by having a fulltimegroup of experts, such as SMG.

16REPORT OF THE SESSION7.1.6The majority of the Board concluded that the SMGshould be establishedas soon as practicable.The delegate of the U.S.S.R. maintained hisposition that such a decision was premature until the situation had becomeclearer.7.1.7 The Board adopted the terms of reference of the SMG as laid down1n Annex X to this report.The need for international financial supportThe Board then turned its attention to the need for internationalcivil servants to serve on SMG and to other items for which internationalfinancial support would be necessary.7.2.2 It was agreed to support the relevant proposals of the InterimPlanning Group, adopted at its London session, namely that "international fundsshould be used to pay the recruitment expenses, salaries and allowances forthe director of the Scientific and Management Group and his deputy, thecorresponding expenses for the clerical and secretarial staff, and the expensesfor all official travel carried out by any members of the staff of the group inthe execution of official duties for the group." (See paragraph ofGARP Special Report No.2). Any offers to pay from national funds the salariesof the director of SMG and/or his deputy and the travel on duty of the staffof the SMG should of course be accepted, provided that this would not hinderin any way the efficient execution of the tasks of the SMG. In this connexionit was pointed out that the "Convention on Privileges and Immunities of theSpecialized Agencies" contained provisions for experts who, though not theholders of United Nations "laissez-passer", have a certificate to the effectthat they are travelling on the business of a specialized agency.They shouldthereby receive facilities similar to officials of specialized agencies regardingthe speedy provision of visas and other travel facilities.7.2.3 It was moreover agreed that in some specific problems the SMG wouldneed to be able to call on the help of consultants for advice or to convenemeetings of small groups of experts to discuss these problems. Whenever possible,the services of such consultants and the travel expenses involved in suchmeetings should be met as part of the national contributions to GARP. Thecomposition of SMG should also be such as to minimize the need for such outsidehelp. Nevertheless, the Board felt that it would be wise to include someprovision for the international financing of consultants and meetings of experts.

REPORT OF THE S~SSION177.2.4 The Board accordingly invited the Secretary-General to ensure thathis budget proposals to Sixth Congress contained adequate provision for thefollowing items:Ca) recruitment expenses; salaries and allowances of thedirector of SMG , his deputy and two secretaries;(b) WMO Secretariat support, including facilities for sessionsof TEE and for GATE publications;(c) services of consultants and meetings of groups of experts;(d)(e)official travel by members of SMG;cost of communications.Members of the Interim Scientific and Management Group were requested to assistthe Secretary-General, as required; in estimating the costs of items (c), (d) and(e) for the period up to 1975.7.3 Location of the SMG7.3.1 The Board noted that the WMO Executive Committee had requested theBoard to decide upon the location of the SMG. The representative of theUnited Kingdom confirmed his Government's offer to provide host facilitiesfor the SMG at Bracknell.7.3.2 The Board considered that Bracknell would provide SMG with thenecessary scientific atmosphere and facilities, including ready access to avery powerful computer, and therefore decided to accept the ~nited Kingdom offerto house the SMG at Bracknell.7.3.3 It was reported that accommodation at Bracknell would be availablefor the SMG by about October 1971 and the Board agreed that the SMG should beestablished at Bracknell at that time.7.4 Interim arrangements7.4.1 The Board expressed its great appreciation of the work accomplishedby the consultants serving on the Interim Scientific and Management Group and ofthe invaluable assistance provided by the Joint Planning Staff and the WMOSecretariat.In the confident hope that such assistance would continue to be provided,the Board recommended that until such time as the SMGcould be formally establishedthe ISMG should serve in this capacity.It was further recommended thatDr. J. Kuettner should be designated as senior consultant and, as such, should

18 REPORT OF THE SESSIONdirect the activities of this group; as a consultant he should continue to reportto the Secretary-General of WMO on administrative matters and on matters thatrequire formal communications with Members and other organizations. On scientificand technical matters he should report to the chairman of TEB.7.5 Liaison with Joint Planning Staff7.5.1 The Board considered that it was important to make provision for theJOC to fulfil its agreed responsibilities for keeping under review theplanning of GATE to ensure that the scientific objectives of GARP will be met.The chairman of JOC reported that, with this in mind, JOC had authorized threeof its members to act individually, as appropriate, on behalf of JOC in respondingto any query from TEB or SMG with regard to any matter that may come up in planningthat might jeopardize the accomplishing of the scientific objectives, or that mayon the other hand improve the scientific possibilities of the GATE.7.5.2 The Board accordingly decided that the SMG should maintain easy andquick communications with JOC, via the JPS.

REPORT OF THE SESSION198. REVIEW OF THE NATIONAL CONTRIBUTIONS FOR THE TROPICAL EXPERIMENT8.1 The Board noted that representatives of Members at the first sessionof the TEC who did not participate in the first sess~on of the TEB, hadprovided information on their possible national contributions to GATEGARP Special Report No. 3, section 4.3).(see8.2 The Board ascertained that the intentions of countries to make shipsand aircraft available for GATE were unchanged from those announced at theBrussels Conference on GARP in March 1970 and reiterated at the Londonmeeting of the Interim Planning Group in July 1970. It was indicated thatsome countries were prepared to augment or modify their contributions asthe development of the plans for GATE made more specific requirements apparen~8.3 The representative of the United Kingdom stated that a polar-orbitingsatellite with meteorological instrumentation, earlier indicated as a possibility,could not be provided by his country at the time of the experiment.8.4 The representative of the United States of America stated that hiscountry is planning to launch the first SMS/GOES* in mid-1972. If all goessmoothly, a second satellite which could view the tropical Atlantic area maybe launched by mid-1973. These satellites will have the capability of providingnearly-continuous clnMd imaging both by day and by night. They willmeasure cloud-top temperatures and, in cloud-free areas, the temperature ofthe earth's surface. They will also have a facility for the collection ofmeteorological and oceanographic data. The representative of the U.S.A.further informed the Board that ground station facilities for the firstgeostationary satellite are assured. A second ground station which would berequired for the full utilization of the second geostationary satellite forthe purposes of GATE, is also planned. The implementation date of thissecond ground station has not yet been fixed; more definite information onthis question is expected to be available early in 1972. Finally, the U.S.A.representative stated that the TEB will be kept fully informed of the progressof plans for these satellites.* Synchronous Meteorological Satellite/Geostationary Operational EnvironmentalSatellite.

20 REPORT OF THE SESSION8.5 The representative of Portugal observed that in the deploymentof ships considered by ISMG for the E-scale network (see Annex VIII), ithad been noted that one ship could be replaced by a suitable island stationin the Cape Verde archipelago. He stated that Port~gal is prepared toestablish a rawinsonde station at Praia, on Sao Tiago, about 200 km southof Sal, rawinsonde station, if ground station equipment can be made available.Portugal will man and supply the station for observations to be made asfrequently as may be required.8.6 A draft questionnaire on the performance characteristics ofships and aircraft to be employed in GATE was reviewed. It was suggestedthat the questionnaire be expanded in the form of an extensive check listto elicit uniform replies on the technical characteristics of the platformsand their instrumentation.8.7 The question was raised by the ISMG concerning the identificationof national experts to whom the questionnaire on the characteristics ofships and aircraft might be addressed.It was pointed out that, becauseof the varying national agencies involved, all such communications should besent by the Secretary-General of WMOto the permanent representative of thecountry concerned.

REPORT OF THE SESSION219. DATE AND PLACE OF NEXT SESSIO~9.1 The Board noted ~hat the TEB regulations stipulated that theconference facilities of the WMO building and the services of the m10Secretariat will be made available for sessions of the TEB. It wasaccordingly agreed that sessions of the TEB should normally be held inGeneva.9.2 It was agreed that a short session of TEB would probably beuseful as soon as the decisions of Sixth Congress regarding WMO supportfor GATE become known. As it seemed likely that the relevant Congressdecisions would be taken towards the end of Sixth Congress, it was feltthat this session of TEB should be convened immediately after, ratherthan during Si~th Congress. The chairman of TEB was authorized toconvene a session of the Board in conjunction with Sixth Congress on anad hoc basis.9.3 As reported in paragraph 4.6.2 above, the Board considered that itsnext regular session would be necessary later this year in order to review thepreliminary plan for GATE.The chairman was requested to determine in consultationwith the Secretary-General of WMOthe most appropriate date for thesession in the light of the progress achieved in the planning of GATE.9.4 The Board realized that in between sessions of TEB occasions mightarise when action would have to be taken on behalf of TEB.The chairman wasauthorized to take such action as appropriate, in consultation with other membersof the Board.10. REPORT OF THE SESSION10.1 Before the end of the session, the Board adopted the maintexts for incorporation in the report of the session. The chairmanwas authorized to approve the final version of the report, after theediting work had been completed by the secretaries of the session.10.2 The Board further recommended that the report of the sessionshould be published in the GARP Special Report series and that it shouldbe available in the four official languages of W}ID in time forconsideration by Sixth Congress.

22 REPORT OF THE SESSION11. CLOSING OF THE SESSION11.1 The representative of the United States, speaking on behalf of allthe participants at the session, thanked Dr. B.J. Mason for the very efficientand friendly way in which he had conducted the session.11.2 The representative of RA I expressed his appreciation to all concernedfor having made it possible for him to attend the session, which he had found tobe both fruitful and instructive. He made a plea that, in presenting the purposesof GATE to governments, adequate attention should be given to the economic benefitswhich might be expected.11.3 The representative of the Secretary-General thanked all participantsfor their contributions to the session. He hoped that members of TEB would giveimmediate consideration to the needs of the Interim Scientific and Management Groupfor more support.11.4 The representative of ICSU recalled the earlier successful collaborationbetween WMO and ICSU in connexion with the International Geophysical Year. Herecalled that the first suggestions for an artificial satellite were made in 1954,just three years before the first satellite was launched and expressed the hopethat the three years which remained before the opening of the GATE would be equallyproductive. On behalf of ICSU, he expressed his gratitude to WMO for having providedthe excellent host facilities for the session.11.5 The chairman then thanked the Secretary-General of WMO and his stafffor their very effective support. He declared the session closed at 3.30 p.m.on 24 February 1971.

23ANN E XILIST OFPARTICIPANTS1. Representatives of Members of WMOMr. M. Quoilin principal delegate BelgiumDr. W. Cameron principal delegate CanadaMr. L. Facy principal delegate FranceMr. A. Chaussard delegateMr. J~P. Labarthe delegateProf. H. Hinzpeter principal delegate Federal RepublicDr. K.H. Hinkelmann delegate of GermanyMr. A. Silva de Sousa principal delegate PortugalDr. B.J. Mason principal delegate United Kingdom ofMr. R.F. Jones delegate Great Britain andNorthern IrelandDr. R.E. Hallgren principal delegate United States ofMr. N. L. Durocher delegate AmericaDr. D. Sargeant delegateProf. V. Suomi delegateDr. J. WallacedelegateMr. G.D. CartwrightdelegateDr. I.G. Sitnikov principal delegate Union of SovietMr. O.V. Krivonogov delegate SocialistRepublics2. Representatives of regional associationsMr. C.A. Abayomi RA IMr. R. Caracciolo RA HIDr. R.E. Hallgren RA IV

24 ANNEX I3. Representatives of international organizationsAdmiral W.LangeraarIOCMr. F.W.G. BakerICSUProf. B.BolinJOCDr. B.R. DoosJPS4. Representative of the Secretary-General of WMOMr. O.M. Ashford


26ANN E XIIIREGULATIONS APPLICABLE TO THE TROPICAL EXPERIMENT BOARDApplicabilityThese regulations, which apply within the framework of theAgreement between WMO and ICSU on GARP, relate to the TropicalExperiment Board (TEB) for the GARP Tropical Experiment in theAtlantic.Approving AuthoritiesThe regulations are approved jointly by the Executive Committees ofthe World Meteorological Organization (WMO) and the International Council of.Scientific Unions (IOSU) and may only be amended by decision of both organizations.CompositionThe TEB shall be composed of members who shall be the officiallydesignated representatives of the Member .governments which have si~ifiedtheir intention of contributing substantially to the GARPTropical Experiment in the Atlantic and a representative each ofRegional Associations I, III and IV.Each such Member government shall be invited by WMO on behalf ofWMO and ICSU to designate a representative to serve on TEB, preferablyon a permanent basis.On the recommendation of TEB, \iMO should invite additionalMember governments, whose participation on the TEB is considered to beimportant for the success of the Experiment (for example, Members providingmajor operational bases for the Experiment), to designate arepresentative to serve On TEB.FunctionsThe functions of the TEB shall be to act as the central internationalbody for the planning and implementation of the Experiment.In exercising these functions, the following principles shall apply:(a)Due regard shall be paid to the views expressed by the TEC andto the overall arrangements for GARP approval by WMO and ICSUand in particular the responsibilities of the JOO, which inbrief are to act in a review and advisory capacity to the TEB*;*Full details of the agreed JOC responsibilities are given inGARP Publications Series No. 1, Appendix 11.

ANNEXIII27(b) Within these overall arrangements for GARP, the TEE shall havefull authority to formulate plans for implementing the Experimentand to organize the implementation. To this end it mayestablish subsidiary bodies and designate or create operationalor other centres related to the Experiment;(c)It is recognized that the major elements of the Experimentwill comprise national facilities, services and personneland the TEE will be responsible for ensuring that these individualcontributions are combined into a co-ordinated programme,having in mind at all times the scientific aims ofthe Experiment;(d) In general the activities of the TEE will be supported andfinanced by the respective Member governments concerned. Ifother resources are necessary the TEB is authorized to requestassistance from WMO and ICSU.At the opening of each session the TEE will elect from itsmembers a chairman who will normally oontinue to serve in that capaoityduring the session and thereafter until the next session. He maybe re-elected without limit.Secretariat supportTo the extent that secretariat support is necessary from outside,this will be provided by the Secretaries-General of WMO andICSU. In particular the Secretary-General of WMO will be the channelof communication between TEE and participating governments. TheSecretary-General of ICSU will be kept fully informed of any actiontaken by the Secretary-General of 1f.MO in this capacity.SessionsThe TEE shall hold sessions at dates and places which it shalldecide in consultation with the Secretary-General of WMO.Invitations as appropriate to attend or be represented atsessions shall be sent to the following:(a)All members of the TEE;(b) WMO, ICSU, IOC and JOC;(c)Additional experts invited on a personal basis, all such invitationsbeing decided upon by the TEB itself.The conduct of business at sessions shall mutatis mutandisfollow those prescribed in the WMO Regulations.

28 ANNEX IIIThe sessions shall as far as possible be arranged withoutfinancial cost to WMO and ICSU. In particular WMO and ICSU will notmeet travel or per diem costs of participants to the sessions (otherthan such costs for participants specifically nominated as WMO andICSU representatives). WMO will, however, provide the conferencesecretariat for sessions as well as limited linguistic supportduring sessions. It will also reproduce and distribute pre-conferencedocumentation and the report of each session in English, French,Russian and Spanish, as necessary.The conference facilities of the WMO building and the servicesof the WMO Secretariat will be made available for sessions of the TEBor its subsidiary bodies.Financial arrangementsThe TEB shall fulfil its functions in the most economicalmanner. It shall have no independent budget and as far as possibleits affairs will be conducted within limits of national contributionsand existing Secretariat facilities.PersonnelSubsidiary bodies of TEB may be headed by a director and deputyappointed as international staff. Otherwise, the activities of TEBand its subsidiary bodies will, as far as possible, be conducted byutilizing staff provided and paid for by the participating Membergovernments. Any international staff will on the other hand receiveappropriate contracts from WMO. Such international staff will ingeneral be appointed at the request and on the nomination of TEB. Innominating such staff for scientific duties, the TEB will give dueconsideration to the views and proposals of the JOC.ReportingThe TEB will submit a report on each session and an annual reportto the Executive Committees of ~rMO and ICSU. Copies will also be sentto all members of the Tropical Experiment Council and of the JOC.Each session report will contain the decisions taken by the TEBboth as regards those taken on subjects within its own jurisdictionand those which require the approval of WMO and ICSU (i.e. resolutionsand recommendations in WMO nomenclature). The annual report shall containa review of all activities of the TEB in the preceding year.

29ANN E XIVPRESENTATION AND REVIEW OF PROGRESS OF THE WORK OF THE CONSULTANTSThis text was orally presented to the TES by Dr. J. KuettnerGeneral remarks1. The scientific objectives of the Tropical Experiment are now ratherclearly spelt out. The Interim Scientific and Management Group is facedwith the task of translating them into observational terms. In order todo this, the scientific objectives must be passed through a number oftechnological and practical filters in the hope that the quantitativeend-products fulful the scientific objectives. This is, in principle,not different from any other field project but, since a costly programmesuch as the Tropical Experiment is a "one-shot deal" and should not berepeated, it is essential that the design be optimal. This, in turn,requires that the group is in possession of a vast amount of backgroundinformation.2. The group has spent at least half of its time educating itselfaccording to the more or less accidental talents represented in the group.Advantage was taken of visiting experts, and information so obtained wasdocumented by a number of internal working papers and, in each case, bythorough oral presentations. It is felt that the nucleus of this grouphas now a much better scientific, technological and operational pictureof the project and the problems involved than was the case 3 months ago.3. The other half of the group's time was spent in reaching some earlyconclusions in critical areas for the JOC, TEC and TES meetings and withthe development of a preliminary project plan. Thought has also beengiven to some organizational problems.

30 ANNEX IV4. First a few remarks on the composition of the Interim Group. Themore permanent members of the Interim Group itself were Dr~ N.E. Rider,Dr. I.G. Sitnikov, Mr. M. Tavares and Dr. J.P. Kuettner. Temporary memberswere Dr. N. LaSeur, Dr. M. Dunst, Miss F. Cruz, Mr. D. Seeko andMr. J.P. Labarthe. All made valuable and distinct contributions. TheInterim Group had intensive help from JPS (Dr. R.V. GarcIa, Dr. B.R. Doos,Dr. V.P. Meleshko, Mr. T. Thompson, Mr. S. Ruttenberg) and from WMO(Dr. R.D. Bojkov (full time), while Mr. O.M. Ashford, Dr. D.A. Glaser andMr. R.H. Foote attended many of the meetings).5. Interestingly enough, the differences in nationalities andaffiliations disappeared gradually and were soon forgotten, except thatthe language problem resembled that of our various children in theInternational School of Geneva.Project development plan6. Reference is made to the attached document, called "Planning PhasePlan". It is divided into an "Information Phase" and an "Action Phase".For the Information Phase the group needs a very large amount of backgroundinformation. Efforts in this direction have been started in parallel,rather than in series. By contract, many steps listed in the action columnneed to be properly phased and must be handled in series rather than inparallel.7. The document is tentative and does not give the correct impressionof the staggering amount of information and work involved ~n such shortwords as "instrumentation" (4a), or "data handling" (4b - on the left side),or "scientific end-products required" (1 b), or "data management plan"(7- on the right side).8. Although there is some doubt that if extrapolation is possible fromearlier large field projects such as BOMEX, it must be stated here that theeffort required is unprecedented and no greater mistake could be made thanto underestimate it.

ANNEXIV319. In the Planning Phase Plan, the following points have been attackedso far:I. Information Phase11. Action Phase1 a2 (Questionnaire)4 a (2)1 a1 c (1-3)10. The following annexes contain samples of the work of the InterimScientific and Management Group and will serve to illustrate its approachto the planning effort of GATE.** *

32 ANNEX IVGATE - PLANNING PHASE PLAN. (updated on 9.2.1971)1. INFORMATION PHASE 1) n. ACTION PMASE 1)1. Review general observing networks and aidsSurface and upper air(i) WWW (time-table)(H) Others(iii) Ship and aircraftb. Navigation systems2. Corn -ile information on led cd lotformsaircraft, ships, buoys, balloons)Performance (range, speed, duration,capacityI ete.)b. Present and expected equipment(i) On-board instrumentation(ii) Dato-collection equipment(iii) On-board dato-processing equipment(iv) Available communications3. Compile information on available operationalsupport systemso. Airportsb. HarboursCommunicationsd. Air-traffic controlQuartersf. Others4. Stote of the art assessment5.~:Instrumentation(i) Surface(ii) Upper-air(iii) Aircraftb. Data-handlingCommunicationsd. Platformse. Test procedures and equipmentf. Calibration methodsg. Navigational systemsh. Expected operational status of a. through f.~:Review expected spocecraft support(Manned and unmanned)a. Instrumentation(i) Sensors(ii) Measurements accuracies and resolution(iii) Data output(iv) Required ground facilitiesb. Development scheduleThe Information Phose 1)1 through 5, should bestarted immediately and should be completed beforestep B of Action Phase is started. Phase 11 Ashould also be started immediately.A centrol programme will develop on the problemof inter-action between wave and convectivesystems, including boundary layer, radiation andconvective studies. In addition, a number ofmajor~ programmes may develop, such as anoceanographic programme.A. PRELIMINARY PLANNING (ISMG)B.1. Interpretation of scientific objectivesin observational termsa. Present knowledge·(i) Synoptic picture(H) Theory(iii) Parameterization problemb. Scientific endproducts required(i) Physical mechanisms(ii) Bulk, properties, fluxes, budgets(iii) Numerical and regional predictionc. Anticipated need for observing stationsand platforms (Preliminary lay-out)(i) Fixed stations (A scale)(H) Ships (A, B scale)(Hi) Aircraft (A - C scale)(iv) Spacecraft (A - C scale)(v) Others2. Major programme areas 2 )a. Central programmeb. Related programmes3. Special studies recommended for near futurea. Generalb. Regional4. Recommendations for SMG Organizationa. Structureb. Operating methodsc. Financial requirements5. Determine early technical developments required6. Approximate pro j ect time-table7. Data management planB.a. Technical(i) Collection(ii) Pre-processing(Hi) Analysis(iv) Communicationsb. OrganizationalDetermine real-time (quick look) datarequirements for:a. Monitoring data-collectionb. Day-to-day operational planningc. Early analysisDETAILED EXPERIMENT DESIGN AND IMPLEMENTATION (SMG)IISMGS MG435

33ANN E XVSYNOPTIC FEATURES OF THE ATMOSPHERIC CIRCULATION OVERTHE TROPICAL ATLANTICby Dr. J.P. Kuettner1. With respect to our knowledge of tropical circulations over the Atlantic,a negative fact stands out, namely the almost oomplete lack of continuous observationsover the tropical mid-Atlantic during the northern summer months. So far,data from the African continent and the Cape Verde Islands on one side, and fromthe Caribbean and the South Amerioan continent on the other side have to be matchedby satellite data. Many of the questions raised with regard to the westwardmovingtropical waves have to do with this gap in data. It is hoped that theA-scale network of the GATE will temporarily fill this gap.2. The tropical circulations are strongly influenced by three large-scalefeatures over the Atlantio, some of whioh are and some of which are not representativeof other tropical oceans. These features are shown in figure 1 and are:(i)(H)(Hi)the upper-tropospheric easterly jetstream (TEJ)the shallow southwesterly monSQon over the W&st African coast (SWM)the upper-tropospheric mid~Atlantic trough (MAT).3. The easterly jet under the tropopause, one of the most striking seasonalphenomena of the tropics, is thermally enforced over India during the summer andextends acrose Afrioa, apparently again enforced, or at least maintained bydifferential heating over the Sahara, and then diminishing westwards across theAtlantic. It should be noted that this easterly jet is not characteristic oflarge parte of the Pacific Ocean.4. The second feature, the southwesterly surface current flOWing into Africaand often called the "Southwest Monsoon", somewhat complicates the situation nearthe proposed B-scale area in the eastern Atlantic. In other parts of the world,easterly wind components prevail in the low-level flow at comparable latitudes.Also the sea breeze of South America has to be watched in the lay-out of theexperiment.5. Finally, the upper-tropospheric mid-Atlantic trough stretching east-northeastwardsfrom Central America should be mentioned. It usually lies to the northof the Antilles. Although resembling some areas of the Pacific, it is notcharacteristic of the tropical oceans of the world in general. The mid-Atlantictrough often affects the behaviour of the tropical waves which have a tendency tointensify or "blow up" as they come under its influence.6. It is for these reasons that the Study Group on Tropical Disturbances andJOC have reoommended that the B-scale network be located sufficiently west of theAfrican continent or sufficiently east of the Caribbean isl~~ds to stay out of theseinfluences. These climatological features must also be taken into account in theinterpretation of the data.

34 ANNEX V7. An attempt has been made to get a better understanding-of the existingooncepts and theories on the tropioal waves, the cloud clusters, the ITG andon the nature of their possible interaction, and, last but not least, on theparameterization problem.*8. From these studies one is impressed by the need to hold a combinedType I and II experiment, as urged by JOG. This implies that a good A-scalenetwork must be maintained, with high quality high-level soundings in additionto the B-scale network and the G- and D-scale aircraft programmes which arepresently in the foreground of our attention.9. The above needs are reflected in the tentative lay-out of theobserving networks as discussed in Annexes VII and VIII.* The further discussion of these studies is not being presented due tolack of time.** *

(f Vc:::;c:::;;='.er'.,:,1',','FEATURES OF THE TROPICAL ATLANTIC DURING THE MONTH OF AUGUSTFigure 1".~:.;,...,. ';;"u, '" .1.. .... .: ,j,~: I i"iM~,",,"':I c 3or-J:Io~ ~.' ~"", ....-.." ~---./- -"""'"\..\2!..-»tdN-.- 0- - HiszzIT1x

36ANN E XVISTATISTICS OF CLOUD CLUSTERS IN THE GARP TROPICAL EXPERIMENTREGION AND POSITION OF THE INTERTROPICAL CONVERGENCE ZONEby Dr. I.G. SitnikovAs explained in the presentation of the scientific plan for the GARPTropical Experiment, the Working Group on Tropical Disturbances which met inGeneva, 11-16 January 1971, examined and summarized statistical information oncloud clusters in the GARP Tropical Experiment Region and its relationship withtropical disturbances and the position of the ITC zone in this region. On thebasis of these considerations, certain recommendations were made concerning thechoice of a region for the study of cloud clusters (i.e. region for scale B).On the basis of these recommendations, JOC-V took the decision of which we arealready aware regarding the choice of region for scale B.Members of the ISMG took part in the Working Group on Tropical Disturbancesand also had talks on the questions discussed within the ISMG. This paperpresents certain material on which are based, to a considerable extent, the conclusionsreached by the Working Group on Tropical Disturbances and the subsequentdecisions taken by JOC-V.(1) Figures 1 to 5 demonstrate statistics on cloud clusters in the TropicalAtlantic for 10-degree squares, presented by Dr. N. Frank (U.S.A.). Wehave cloud clusters here, both related to, and not related to the ITCzone, averaged over the years 1969-1970 for June (figure 1), July (figure 21August (figure 3), September (figure 4) and the period July to September(figure 5). From these diagrams it is evident that the main maximum isin the eastern Atlantic at latitude 100 approximately, and that there isa secondary maximum in the western Atlantic to the east of the WestIndies. The great majority of cloud clusters are observed in August,but in the eastern Atlantic there are also quite a few cloud clustersin July.(2) On the other hand the frequency of cloud clusters associated with theITC zone based on data from photographs from the meteorological satellitesCOSMOS, TIROS, ESSA, analysed by L.S. Minina (U.S.S.R.), are shown infigure 6*. Here the percentage of days when cloud clusters were observed* Figures 6-9 are reproduced here from the appendix to Doc. 17 prepared for JOG-V.

37in each 5-degree square is shown for (a) January, (b) July, (c) April and(d) October, in 1966-1967. The maximum frequency is observed in July inthe central and eastern Atlantic (75%) approximately at latitudes 6-8°N.There is good correlation between the data of Minina and Frank on cloudclusters in the ITC zone.(3) In figure 7, diagrams are given showing the trajectories of tropical disturbancesin the Atlantic and neighbouring regions (based on data obtainedby Kry~anovskaya in the U.S.S.R.) for (a) June, (b) July, (c) August 1970.Dots denote places of origin and decay of disturbances with short lifecycle(1-2 days). Moving disturbances with life-cycle 3-12 days occurwest of the Abyssisian Plateau in the belt lying between latitudes 10-23°Napproximately. On average the trajectories for each month coincide withthe mean position of the ITC zone. Clearly this is related to the factthat both phenomena are determined by the large-scale processes developingin the entire troposphere.(4) Figures 8 and 9 show the frequency (number of days in a month) and meanposition of the ITC zone in August 1970 (figure 8) and over a five-yearperiod (1966-1970) (figure 9) (from data given by Stechnovsky and Krou~kova(U.S.S.R.». Mean values were found for 5 0 -squares. It is seen that inthe eastern Atlantic the mean position of the ITC zone is at about 16-17°Nover Africa, between 8-12°N in the eastern Atlantic and about 6-7°N overthe western Atlantic and South America. There is no essential differencein the position of the ITC zone and the frequency of its appearance duringthe course of a single year (figure 8) and five years (figure 9). Consequentlyit may be noted that year-to-year differences in the position ofthe ITC zone are only slight.** *

OO' , ".' I'\I ••••••• '•• 1 ' . . iI! "". (... I ,•._'" '\ ....... . ,. ..., l',...,''-.-, = ", I ...'1' 'Le I ..... 'I_. . .,. V'!"":,,,,,,., I , , .'.•. ,'... , . . . . . .. ',.('"\'c,.. ' ... . . . . •• ... ,[Y i.l'"; / ..•.. ..•••.•,. ,•••••••• .. J.< · , J: ," .,.. ";'! I'" ... , .).. ~.-,~.. v. l.... . .. . . .. .[...~. \~. 5?~ ~ ~v;; ... ' ..-,, " . 0, ,,", '\'., ./'-, ',. '../ I' !. ."" "', JI 'i'" ., .. ..' ,.. _. v.. -.-. I".... r , ..... . . . . . . . . . ...•.... . . ...'"I' ,. ,.' :. ,:\ ~;~ ~ r .,. -. . . . C ) l· . . . I, ','~' ' .. " I '" 1\' "( 1, I'" I • J I ' • .,----.-;, .l __., i_&-:""~'/'/~,. ~."" ....... .l C".£.. - -, ... .. :;. V"'''''~ :: ) ... cTi-,J:: '" , ..'>,~""I ~ _.J.. '--,'- '_.-v-,_, f',." '\ •• - /"} I •'--, ~.• , .', ,\ "0"---7-7"-;"'""., ". .. . . . " . 0 ,0 " •• "'T. . I J...-' ..., , 1:, vi, 1'-, ~o .. •. 0 • , "_ _.• •• • . . • d non-IT.. I.' . • ., .... '. . . . , ITe = .vV"''''-'_~ y~) ~ . 00-: ,.. , -". /~"''''':'-+C~",,,'-./,,,.. · : " \ ) '[',-' \( ... ..', CLOUD CLUSTERS ( (after N• Frank) 'IL, _.-. - ---I -: \ .L.;. .co 1.. ) ..±~~.. ~1.Lo•.·t·,· '. FIe.1 , ) JUNE " . . , . ,: i ...I : . A"rag' : : \ : :: ., '::: 1. 1--.- !. 'I'" 'c' ': (i.,1o·{ 'i:.-..J.. I,L . (1969-1970 Q' ••• 'I:~:~I-lr> :1~~l~2i~4F' •••T•••••••8•••• '1" •••• •••r••••••••••.......·~~_'.._: ~'•0', .· '. L ..._,~ •. "i'-',Li'~~I; ob r-.. ... ... . :': I "::::.. ":::: ... 20' , : : : : . , . I'/'. .. ".". 11_''"'''''''1'7 III 'P2..1' ... iw00~ZrrlX< Hk~~b300'-'-I" .:: ::I::' ',~" .,••· .•• ••• ' o.i_.~ __~ r v~c. .~""""l.r~~\j' , ; • . ,...•.... '., I._ .......• .........l,ILI!0\::,':':" :.: ~_, "' ·········:5 : ···~···I··.::.:::-,~._.\:..i .I·:·: .••• :200> " ''''i- c~f21'G.5"f·:~:.:I 8•• ' ::: .:: ••• :::.V:::::~ ,"1•

:\......... \ '1'" .-;;.. ..~ 1i'('Z. I ·1· '1 "(,r,-'I.'>7 ... . .. . . . . I . . . . . . ..

----------------------------========----_.._-------------------------------..j:>..o... "-.;...... . . . . . '.,'•..••. '1' '" ':.. .... "j: ~.'I' .' ~CLOUD CLUSTERS (ITC and non-ITC )Average (1969-1970)AUGUST(after N.Frank)~z mx

1-- ..........~' >< ~r)::'i . r:?. " . I' ........ . "'o;;ii~.. 1 !~- :;,. (I .• 1\':\,;;,1 '.' '1' ...•••.............. •.• ;:)X...I..",.'.,I" ,.G..p_ .... .\ i.. .. . .. I ,~. (. ''','~"'- 1 ... ..... . ... . . ... . ..... ~__ l- "r'• I.~..; '.J?){' 1\ I' 1..~V.?'_ ..1;.1).11. 'e\'.. "F ", . .. ?ll \ .. . .. , . .. V . j _ _~ ..... : ....G'·'.r\ (..,.,. .",i \itS, ..,.. .. I1_ _

..' : ""'.. .,'.. .I ..... '( "( ",:" : .....I;;... ) i' .\. I.' ,.. (\ .. ·········i:"···· ·\."fj ; \.'-...(. (·I···· \ ......:~.:;:..__.-, :- ):;' ~;.- '''f---..-+- --.._.- ---'i-'-}--6:"'·---··j·~.-3r\1~·- _+ I l, b1~ t \----,'~1~":,/~.""" ,, ' : , '," , .~' .. I ' ' , ,, ' ,, I\;" . '.",.. •••• "1""""If:~ZJ:F{~i17I}~';~'"' •• \"' ••·••••1••••• •.50. ••• ••••r•.•~I'V:>zZI'T1X< H:1........ ::3:: .::':'·3": '·::8:,:: :,::7::': :::q:~:: ::::2.:::. :::2,:*::,:::::::::!:: ..

abcd0'0 lJJ~ANNEX VI.,1\1 ____~~_

44 ANNEX VIt.", 1 , 90 ,45 30 ,,4J'\ I'-.. ,~.._._- V ~ ~ k ~ ~-.;~ T.~.E LeEN "\ -. ·~·VQ,CON~ lE\) .\ ~ ~ ~.•} .. If ~"0"..\.'.y'\ t~ U/ It. ~-r.~ "="-. . . :;....;::.'.'~ \"" V~'--- ~ ~ 4Lo". ..d:"'*' '/ ..~~.~:x . :-:.: . '- . ~./""" .0.. .n0 .... '- 1:"- ~ 1--"-:/" 0 L-'-'i.X ~ :::::: ,:\ '", IIIi ~ I>"--. \ " G VDI""'-.! .\ 1...1\ , 1/ J ~· ."301\ "I I \ I (:iIi I 1/' I'---''.., "/-"'--I--...- -~~ f \'-.,--, ~I~r\I---1-- .. - ....~ mL4A ("""\/; ....,' . :"-.':H ,Il> SKY .... 0 ..'\...... JP K" "'"--t-""" :JO E ¥-i_,:>~ •• ! .J-.rr'"" - /'0t r. FRAN £5 A" ."'" "\' ? >-'5 "'",0:oYJ 5> ....-/I"';i -- .'--~l... )! . ~-- ~ --. I- ~0 l-:.-;, ~ ~\~\';>~.II #". ~ ~ .(],l------ 7I"'-11\0!,0\ 11 i ) \1~. . .1 'Ior;.· '...\ I'-.. I .. (~TV I'-.. ~ h.... 1--.,so~ f 1 '~'I/r--.. - l \1\C','0 ",,' ~.'~ '''\I'''' K W ref,. I V ~. I~\'\~"- t'----f-A ~'i~f r>,..:;:. .JS..:D DIl -rH:! 1/ L ::;::: "/ .~ '\ \ ." ....... ~....•0'o~rl 'f'... ./ /./ P9:If.\';>"'. -1,0o '~:?; ...0..00·. ,>.~ ...... . .b ~ ~o 0.. ". ~... .;::(:: ~o • -") • • . 0 l01/ .000 I>" r \ .V /"\'\ , If ) ~, "0 10' 90 ,. 6. 45 30 .. ..r-030.· .45FIG. 7Trajectories of tropical'depressions in the Atlantic and theadjaoent areas in 1970/after Kryzshanovskaya/. a) June,b) July,c) Allgusto Dots denote places of origin and decay of disturbanceswith short life-cycle.

ANNEX VI 45,r -.1-\ VJ I-'" ~ ~,~ ~ 2....V / ( Y 0120 ~O54. 3 1 :0'"bJ'F~o d""='~po.g {) L rvI~ ~If t.!)~.~~ ~:f I~ JS\\ \~ ~. SJ D p b~'1~ ~)~~. ~os' ~ .~ ~&30:\..~ r \' ,",,:1IL,I~~1'\ ~ I:Y tJL\ ~ ,(() I~IF' ,.)Ir-f-.l1/vo I~ ~ .~ [) 1\ ~ L.I'---. v- I"-] IL, ,"'- I);' i J~ ~------ ~l\~ ~./( , - V ~ r-.. r-... 1-...., J 10""r ~1\ ) ~ kil~, ,'\\ ~I--"l ~ ,. /' ~~~L::..- .t=Idv-t> = . .-:: j;::::- ..... 7.!: ;"'\.I';,~~ ~I 10,.....\ ,.:::;::::/' r-- ~ IS ~15 - ,~ -!::=f p- ,1'/ t'-.1- r;;::: ~ "' ~ ~~" .-r -""Jo" .-- ~-...-: f? rc, ~v~...•._.I'"J:/t v 'I0v0(V!1"\ ~\IV vi" .\\ :( .!'. /'~ . f' !f-l / (\ .\ /f--J..r-JO ~ I).. / ~ / 't e:r- L/i~"\"lJ•• -t--- . - -- -----..t>~ ~- ?P FIG. 8""., Frequency (number of daysper month) and mean position~,;;>, of ITC zone in AUKUst 19~!~lI I;)ji: "J J L ~ 1 1.1 1 I I 1 11 ~"(after Stechnavsky and Krau ka~aI I, i.>I I I I I ~hJ I20 90 75 50 15 o 15 30 45 60". 4'30,I'"•I

--......46 ANNEX VIi~pIU.. ~t-; 545 3 I ,°~~ Jp';.., f:.v -~ 1\"0Ir 1-1"~ f ~ ~,p f)/ ( V ~~,.. I) .t'l ~IL ~~ \ ~ U [J ~' ~ -...,'r< ~~~~....~.~~ ~:f I~ I~ ~• "~:L, ,~f-J""~ ~ 1'\ re· c:Y IV ~\ ~ (. 5(,c- .--1 1,5 -'0 ~~ i ,--) \ '0 ~I v-'0 ~~ I,.)~,-L, :-/ I--~ ~--v - ,/,~ "-- 2. l.j 812.)30'"\ ( '---- ---. c--~~ ( \\'"":'.. /-"'- ~ /-)Y-:( Z ),~I" \ . ,q;:;- .-'"'' ...... ~-",~\ / ~~'" [·r-- ""~ -:l ".- ~ A" "'-,..~.:': :dv-- ~= --J1.-- , - ~>bt lFrequenoy (numbar of daysper month) and mean position.. of I'1'0 zone in August, averagedfor 1966-1910(after Stechnovsky and Krou'fkova)'"Qji',,V ~, I I 1 ..vII ..... I I I'os 15 606O/" '0 " ° " " "i°

47ANN E XVIIOBSERVATIONS FROM WWW UPPER-AIR NETWORKAND SHIPS AND AIRCRAFT OF OPPORTUNITYbyMr. T. Thompson1. From figure 1 to this annex it can be seen that within the GATEarea as a whole, 106 stations are recommended to make radiowind observationsat 00 and 12 GMT. The recommended programmes are reported to havebeen completely implemented at 22 of these stations and at 38 others theprogrammes have been at least partly implemented. As regards radiosondeobservations, 83 stations are recommended with observation programmes at00 and 12 GMT. At 18 of these stations the programmes are reported ascompletely implemented and at 33 other stations at least partial implementationhas been reported.2. In the eastern continental portion of the GATE area (Africa)about one-third of the recommended radiowind observations have been reportedas implemented at 00 and 12 GMT. However, to the north of 5°Nlittle more than one-fourth of the programmes have been implementedwhereas to the south, almost 40% of the radiowind programmes have beenimplemented. The status of implementation of radiosonde observationsin this area is about the same as for radiowind observations.3. The situation over the western continental portion of the GATEarea (Central America, Islands of the Caribbean and northern SouthAmerica) is only somewhat better. About 40% of the recommended radiowindobservations have been implemented but there are marked contrastsin different sections of this area. To the north of 5°N, more than 80%of the recommended radiowind programmes have been implemented on theIslands in the Caribbean Sea and in South America whereas in CentralAmerica 10% have been implemented. To the south of 5°N about one-fifthof the recommended radiowind programmes have been implemented. Thereis a similar difference throughout the area as regards radiosonde observations,although about one-half of the recommended observations havebeen implemented.4. From the above it is clear that the requirements for A-scaleobservations in the GATE area are at present far from being met. Anincreased effort for an early implementation of the WWW Global ObservingSystem is therefore absolutely necessary if the GATE is to be successfullycarried out in 1974. Even if all stations included in the WWW

48 ANNEX VIIprogramme are implemented, there will still be considerable gaps and31 additional stations would be required if the requirement for 500-kmspacing is to be approximately met. Although it may not-be critical ifin some land areas the requirements are not fully met, it will be ofimportance to have some of the gaps filled. For this purpose it shouldbe explored whether temporary-stations could be established under cooperativemanagements between countries and whether pilot balloon observationcould be used to enhance the radiowind observing network.5. The GARP Basic Data Set Project, which has been carried outunder the co-ordination of the Joint Planning Staff for GARP with thesupport of WMO, has provided as a by-product a limited test of theactual output of the WWW system during two periods of one month's duration,namely November 1969 and June 1970. The latter period has beentaken as a basis for this study. The data processed at the WMC inWashington during the June period were thus examined to obtain someidea of the number of observations that are being received on a routinebasis. The results are provided in figure 2.6. The material referred to above presents deficiencies in thefinal output of the total system (including the computer at the WMC).It does not, however, give any clue as to the source of the deficiency.There are, of course, a number of possible reasons why the data werenot received. On one extreme, the reason may be simply that the observationswere not made. On the other extreme, it could be that the computerat WMC failed to accept the data for one reason or another. Itis felt, however, that the results shown in figure 2 are in a greatmeasure indicative of the present state of that part of the WWW GlobalTelecommunication System which handles the data from the GATE region.7. Well before the beginning of the GATE, it will be necessary tocarry out scientific studies using data from the upper-air stations inthe GATE area. These studies are necessary to achieve the translationof the detailed scientific requirements into a feasible experiment plan.It is therefore important that the WWW implementation schedules shouldbe accelerated wherever possible. An assignment of priorities and aco-ordination of the planning efforts for the GATE with the action takenin the VAP may help to accelerate the implementation of certain statiorothat are considered vital for these studies. Tentative lists of thesepriorities over Africa are given in figure 3. The stations were selectedwith the view of ensuring that at least several "lines" of stationsare implemented across Africa to allow for individual cross-sectionsand wind profiles to be analysed. These lines are shown in figure 4.8. Under no circumstances should the formulation of the list betaken to indicate that a full implementation of WWW plans is not highlydesirable. Only if the latter cannot be achieved by 1974, concentrationof the stations listed would be conductive to the fulfilment ofthe aims of the GATE.

ANNEX VII499. The WWW plan attaches particular importance to mobile shipscarrying out radiosonde/radiowind observations. According to the ThirdStatus Report of WWW Implementation, July 1970, some WMO Members arealready actively engaged in plans for equipping ships with the appropriateobserving facilities. Further, if all of the present plans canbe implemented, there would be approximately 70 mobile ships carryingout one or both types of observations by the end of 1971.10. Aircraft meteorological reports from commercial aircraft havealso been recognized as providing valuable data from the upper-air, particularlyover the ocean and other sparse-data areas. Within the contextof the WWW, arrangements for the selection and distribution of aircraftreports for synoptic purposes are being carried out on a globaland regional basis through the established regional collection centres.11. Even if the full WWW plans are implemented,it will be necessaryto enhance the WWW facilities in the GATE area, in particular overocean areas. For example, a preliminary examination of the results ofthe GARP Basic Data Set Project shows that although it is possible tosignificantly increase the number cf reports from commercial ships andaircraft, the observations are made along rather narrow routes. Theseare shown in figure 2 and as can be seen, there will remain large gapsover the ocean, from which it will not be possible to obtain data byWWW arrangements. The.experiment will therefore require some dedicatedships, on special locations, which should take upper-air observationsfor the Scale A, in addition to the ships devoted to the Scale B. Theywill have to be operated either nationally or internationally. It maybe possible, for example J that one country would be willing to make aship available and another the required observation facilities.12. The preceding discussion shows that the problem of implementingan adequate observational programme for the Scale A during the GATE isa complex one. It should be emphasized that in order to serve the objectivesof the experiment, the observing system as well as the:~orrespondingtelecommunication system should be implemented and fully testedwell in advance of the starting date of the GATE and the programme maynot succeed unless there is a serious, urgent and fully co-ordinatedaction at the national, regional and international level.** *

50 ANNEX VIILegends to Figures 1, 2, 3· et 4Explanation of Symbols used in Fig. 1, Fig. 3, Fig. 4(Network of WWW Upper Air Stations at'OO and 12 GMT in'the GATE Area)LEGEND:aDRadiosonde Observations recommended at 00 and 12 GMT~LACK:Radiowind " " "Observations reported as made (Implemented)11 11 tI"WHITE: Observations not made but planned by 1911 (Not Implemented)oObservationsnot made and no plans known (Deficiencies)Indicate. Observations included in the Congress-V Suggested MinimumAdditional Programme for 1968-1911Explanation of Symbols used in Fig. 2(GARP Easic Data Set Project: RadiosondejRadiowind ObservationsAccepted at WMC Washington during June 1910)LEGEND:(] 0000 GMT D 1200 GMTNumber of Observations CN) Received Per Observation Hour fromStations Listed in Fig. 1 as Implemented28 or more NI~93%23 " "but less than 28 (71%~N

NETWORK· OF WWW UPPEP AIRSTATIONS AT 00 AND 12 GMT IN THE· GATE AREAFigure 1 ANNEX VII 51t•n90 _ 80 n 70 60 50 40 30 20 10 0 10 20 30", ()0384,& 397~3866 594223024.~~llS97.~ 1 ~ ~501 .@ 48 7531 ~~7300521 ~fer (i'{24.Ei:l '001 " 1 954 \~87988 D @90 046(ID ~o ~52Q et503•1L, 1rk~ ~6:~ 361 1230od1090~~~41 16

ANNEXVII53Figure 3PRELIMINARY LIST OF RECOMMENDED PRIORITIES FOR IMPLEMENTATIONOF WWW UPPER AIR STATIONS REQUIRED FOR THE GTAESTATION PRESENT IMPLEMENTATIONSTATEREQUESTEDA. FIRST PRIORITY..At about WoW61499 Aioun e1 Atrouss2R61290 Bamaco1 165548 Man~61832 Conakry/GbessiaZR65660 Roberts Field &•At about 2 0 W61223 Timbouctou ZR A65503 Ougadougu J:, A65418 Tama1e ZR•At about 30 0 E62721 Khartoum 162840 Ma1aka1 a 1..62941 Juba 2R63832 Tabora 2R•..jAt about 43 0 E..63475 Gabre Dare63260 MagadicioB. SECOND PRIORITY..At about 9 0 E61024 Agadez ZR65046 Kano ~•..65123 Minna Lt64910 Doua1a~ 1..61931 Sao Tome &64500 Librevi11e & ..64400 Pointe Noir L, A

54ANNEXVIISTATIONSAt about 20 0 E64753 Faya-Largeau64700 Fort-Lamy64750 Fort-Archambrault64650 Bangui64005 MbandakaAt about 30 0 E64076 Bunia64387 Kigali67475 KasamaPRESENTSTATEIMPLEMENTATIONREQUESTED6.1,.1,.

THE WWW UPPER AIR NETWORK BETWEEN 1005 AND 200N IN AFRICAApproximate Longitudes of Priority Stations in the GATEFigure 420 I59&10,,([~)20 10 0 10~"'0241~ ,I223! r I!6~1 £,I :Ji.. \.11\87~(!5°016, 1:, 1:~.- . 832 5481017870~--91020750. I!I li650 :7JQ..»~I 840 I! 1!125~ I zZ~; .-661 I11~.~ l'T1XI-----I U I.

57ANN E XVIIIPOSSIBLE SHIP DEPLOYMENTS AND MOVEMENT SCHEDULES AND ASSOCIATEDINSTRUMENTAL PROBLEMSIN GATEby Dr. N.E. Rider1. In this annex three aspects of the planning and implementation ofGATE are considered.These are:(a)some possible configurations for the deployment of ships for theoceanic A- and B-scale observing networks (which is the subjectof Appendix 1);(b)two examples illustrating how the numbers and performance of theavailable ships determine the actual periods in which observationswill be possible (which is dealt with in more detail in Appendix 2),and(c) some early consideration of the instrumentation to be ~ssd aboardthe ships to satisfy the observational needs.Possible configurations and positions of ships2. Figure 3 of App.l illustrates some features of the Atlantic area.The mean location of the ITe in August is plotted together with someinformation concerning the positions of merchant shipping and commercialaircraft routes. The numericals refer to the numbers of cloud clustersin each 100 square in June, July and August respectively, and the tworectangular areas enclosed by the heavy lines identify the prefffired locationsof the B-scale areas, which were considered by JOC-V follQwing the repor~of the SGTD.It will be recalled that it was recommended that the bestarrangement would be to site the B-scale area in the east Atlantic for twomonths followed by a third month - August - with the B-scale area in thewest Atlantic, if such an arrangement proved logistically reasonable.

---~~_.. ~1EXAMPLES OFPOSSIBLE SHIP MOVEMENT SCHEDULES FOR THE GARP TROPICAL ATLANTIC EXPERIMENTANNEX VIII 69DAY NtlMBER 2 4 6- 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 100.-l -SCALE I vVVVW7Z7Z7Z/Z/ZZZ7Ay\~AA'M//I / l / / l l Z Z Z l 7f\.NVV\!V\/VI/Z I I I 1777 I 1777N'J\f\I\I'AI '\I\I17ZZZ21117 I II II\J\; "VVV'J7ZZ IZ 1//777 7 1/NVV\l'v '\f\JII 11117111177 /WY1"'1P=ll=>0 SCALEK-v\I\I\lX1Z 7 7 / I 111/17777t>0H-l -B GROUP 2j'lX1/ / / / //// / / / / / / / / / / /// /I)( A/\~Z22'27---LZ7ZZZZ/T-axfv'\N' V"/XIIIIZZZZIZZIZI I I / IZ Z I ZZa>4}\--0H""-VGROUP 3 \N\I'JXI/ZZZIZ/Z/ZZZZZZ/WV\/\) v'4XIZZZZZZZZ//ZZ/ZZ7ZZ/W ..j\MY/77:2/iJ\Jl 1V\1\/'V?1771111IZZ7ZZZZZZ7Z4N\fV\r-SCALE1"'1 GROUP 2d////////////77/~/~t /0tAj\VOZZZZ///ZZZ/VVVV'v,/VJ7 Z 7/7777IIIII III IIIII Z\JV-A..:l- GROUP 3 t\!VVvlZlI IIIZZZZZ//ZZZZZZ/JVVVV'vP("""1"'1SCALExMIIII IZ I II I 1/7ZIIZZZZI Z1XIJ'BGROUPl- ~~///////////////// 1VV'v I ,t'!XJ7777Z77777277ZZZZW ),1/ )/))--yVV\IXJIIIIIZZIZII / I 1 I1 IIIZ ZZt4Mf'r~-J:Q l=> GROUP 2- v"VV';l8177 I Z I Z IZ I 17 Z / Z ZJ> ) ., ., ) , ) 1't -J'lXlZ 1 / / I Z Z I 1/7 IIZI//Z Z1XIJ'-t!J- GROUP '"'"V\j\/\iXJIIII IIZ I I I I III I/JI>

58 ANNEX VIIIJOC subsequently recommended that the B-scale area be located in the easternAtlantic (see para. 4.1.4 of this report) and TEB decided to accept thisrecommendation subject to the availability of platforms, base facilities,etc. (see para. 4.6.1 (v) and (vi) of this report,)3. Figures 1 and 2 of App. 1 show possible lay-outs of ocean stationsfor both A-and B-scale observations. Figure 1 refers to the case whenthe B-scale is in the east and figure 2 to the case when the B-scale is inthe west. The numbers of ships required to fulfil these schemes are also'given in the legends and it will be noted that the numbers required forthese suggested lay-outs are in excess of those so far indicated as likelyto be available.4. In Figure 1 (App. 1), the B-scale area does not cover the whole arearecommended by JOC - in particular the SW corner of the recommendedarea is not covered and the axis of the area has been tilted from aN-S direction to a NNW - SSE direction. Both these modificationshave been introduced to bring the area under ship observation morewithin useful aircraft range of the airfields which might be available.It will also be noted that one "column" of B-scale ships is moreclosely spaced than the remainder.we imagine will be equipped with weather radar.The ships in this column are those5. In Figure 2 (App. 1) the B-scale area, now in the west Atlantic, hasa similar configuration. However, the area covered is somewhat tothe west of that recommended by JOC-V again to bring it nearer toairport facilities. In both figures the A-scale network of observingstations is similar and has been laid out on the assumption that rathercloser spacing is desirable in the N - S direction, than in the E - Wdirection since the characteristic scale of the westerly-moving waves islarger in the E - W than in the N - S direction. The need to reduce thenumber of ships required to a minimum has also been kept in mind. Theshort statement attached to the figures displayed in Appendix 1 explainsthese considerations in a little more detail.

ANNEXVIII, 59Possible schedules of ship deployment6. App.2 gives two examples (based on assumptions which may bequite wrong), of the way in which ship movements might be organizedduring the conduct of GATE. It is emphasized that these are onlyexamples and are designed to show:(1) that the SMG must have performance data on the ships thathave been offered,and(2) that it is extremely unlikely that continuous observationsover the whole period of the experiment - the 3 months whichhas been suggested - will be possible.7. In the first example (the subject of Figs. 1 and 2,of Appendix 2)it is assumed that the ships can only stay at sea for up to 24 days ata time, that the number of ships is equal to the number of stations tobe manned,and that ten days will be necessary between each sea periodfor restoring, maintenance and leave.It is also assumed that theA- and B-scale observational periods are to be coincidental.8. These assumptions, together with some others which are set outin the text of App. 2 lead to the conclusions that, in 86 days, only 3 twoweekobservational periods will be possible if the B-scale area remainsin the east Atlantic. If the B-scale area is to be transferredfrom east to west., then in 97 days only 2 two-week periods in the east,,followed by 1 t~o-week period in the west, plus a subsidiary A-scale weeklyperiod (when ships are on passage from east to west) would be possible.9· In the second example (in Figs. 3 and 4 of Appendix 2) it is assumedthat 50% more ships than stations to be manned will be available for themajor part of the total observational period; that all A- and B-scale shipscan remain at sea for up to 27 days and 33 days respectively, and that thetime required in port between spells at sea is only 5 days.If such provedto be the case, then by dividing the ships into 3 groups, almost continuousobservations could be obtained with the B-scale area in the east Atlanticand agai~,apart from east to west passage time, with the B-scale area inthe west Atlantic. In both instances some ships would be required forrather more than 100 days.

60 ANNEX VIII10. In actual praotioe the sohedules which are likely to prove possiblewill probably lie somewhere between the extremes given in these two examples.It is hoped that the foregoing will show the need for fairly precise data onship performance.Instrumental requirements11. If the requirements have been correctly interpreted, then it isat least highly desirable that all ships occupying the A- and B-soale stationsshould be capable of measuring upper winds to at least the aQ.mb level.It may well be oonsidered that any ship whioh does not have thisoapability will be of doubtful value to the experiment. This appliesto both A- and B-scale ships. If it is aooepted as unlikely that some30 ships will be equipped with suitable radar, or R.D.F. equipment forthis purpose~then it is neoessary to oonsider an alternative method, and theonly one likely to be available is that based on the use of radio navigationalaids. Unfortunately, the Loran system does not cover the whole area ofinterest and it will be neoessary to fall baok on the Omega system whiohmay not meet the total aocuraoy and resolution requirements speoified byJOC. However it seems that the use of the Omega system for upper-windfinding is still in the development and trial phase and it is too earlyto make any definite statement as to the aoouracy and resolution thatmight eventually be attained. The Board might perhaps wish to take note ofthe recommendation on the urgency and importance of this work to the successof GATE, reoalling that there now remain only 5 years for completion of thisdevelopment work and the produotion of the equipment, training in itsuse, eto. It might well be considered that the availability of thissystem is next in importanoe to that of a geostationary satellite. Ofcourse, during the experiment any ship which is equipped with a radaror R.D.F. capability should be enoouraged to use it, if possible incombination with an Omega-based system.·12. This leads to an associated matter. It is to be ass~med thatthe data obtained need to be homogenous and it appears that this may notbe the oase without the use of identical equipment and techniques,particularly in the radiosonde field. This is particularly desirablewithin the B-scale network and is a matter to whioh TEB should giveclose study. The whole subject is very involved and is not made anyeasier by the over-riding requirement to obtain upper-wind data. It will

ANNEX VIII 61have been noted already that, within the B-scale area, the need has been indicatedfor a minimum of about 7 ships to be equipped with weather radar. Ideally all shipsshould have it, but it is considered that this is very unlikely-to be a practicalpossibility. One of the observational needs is to arrive at the rainfall rateswithin the B-scale box and it is not clear how this is to be measured. The onlyhope appears to be a combination of quantitative radar measurements, raingaugesand perhaps some estimate from satellite observations. There are many othermatters to be decided such as the frequency of upper-air ascents which, of course,cannot be considered independently from the sea endurance of the ships, the needfor observations in the sub-cloud layer by the instrumentation of tetheredballoons, radiometer ascents, the accuracy to which surface pressure can be determined,etc. Consideration will also have to be given to the problem of mutual radiofrequency interference.13. In conclusion, it may be stated that, in order to make GATE a success, verysubstantial technical effort and financial support will be needed nationally toprepare the ships (and also the aircraft) for the task.Appendix IA POSSIBLE DEPLOYMENT OF STATIONS TO PROVIDETHE GATE OBSERVING NETWORK IN THE ATLANTIC(Submitted by the JPS)1. Figures 1 and 2 show ways in which the stations might be arranged in theAtlantic in order to carry out the required GATE observational programme for the "A"and "B" scales. Figure 3 illustrates some related facts concerning the GATE oceanarea.2. These figures are largely self-explanat0~y, However, the following notesprovide some additional explanations and list the considerations which have determinedthe deployment which is shown in Figures 1 and 2.(a) The 8 - scale areas approximately coincide with those recommended by the JOC.However, the area in the eastern Atlantic (Figure 1) extends somewhat to thenorth of the recommended area to take advantage of the station already establishedat Sal (594). It has also been orientated in an approximately NNW-SSEdirection to bring the network closer to land and hence to reduce aircraftflying time. The SW corner of the recommended area is not covered. It willalso be noted that the need for one ship could be eliminated by the presenceof a temporary station on one of the extreme south-westerly islands of theCape Verde Group. The B - scale area in the western Atlantic (Figure 2) issomewhat to the west of that recommended. Here again the aim is to reducethe distance from land in the interest of aircraft range.

62 ANNEX VIII(b) In one "column" of the B- scale network the stations have been closelyspaced relative to the spacing in the remainder of the network. Providedthat seven of the available ships have weather radars and occupy these positionsit would be possible to obtain good radar coverage throughout anapproximately N-S column some 200 km wide. A substantial part of the aircraftinvestigation of clouds could then take place wiihin this area in which over­~ll radar coverage was available.(c)The considerations which have determined the suggested distribution ofstations in the A- scale are:(i)(ii)(iii)Representation of the large-scale features requires an even density ofstations throughout the ocean;Statistical analyses of the large-scale wind field show that itscharacteristic scale is larger in the EW than in the NS direction.Hence station spacing is arranged to be greater in the former than ~nthe latter direction;The "diagonal" layout appears to be the most economical in terms ofstation numbers and conforms more mr less to the orientation of theadjacent continental coastlines where some U/A stations already existor are planned and can, in effect, extend the ocean network;(iv) Stations are placed at 3t O intervals of latitude and hence there isevery chance that disturbances originating in and moving along theITC will be detected.(d)(e)It is necessary that all ships and other stations be capable of making radiosondeand radiowind observations to at least the 80-100 mb level.It will be noted that the total number of temporary observing stations shownis about 30 which is some 5 in excess of the number of ships so far indicatedas likely to be available.LEGEND:BLACK:WHITE:Explanation of Symbols used in Fig. 1 and Fig. 2(Network of WWW Upper Air Stations at 00 and 12 GMT in the GATE Area)Radiosonde observations recommended at 00 and 12 GMTRadiowind " " " " " 11 "Observations reported as made (Implemented)Observations not made but planned by 1971 (Not implemented)[] Observations not made and no plans known (Deficiencies)OIndicates observations included in the Congress-V SuggestedAdditional Programme for 1968-1971.Minimum

1:,(:')'''',-L 0.:. .....JI')U V .1::> v I'.t-V'" ":;'';,j'",-----:-.-I--~r ':,'.) , (.:; .:'.)"'-.r~-,-r-"---"--T--'-"'---'"! ,".r··..······ ~>FIG. 3 BACKGROUND INFORMATION RELATING TO THE GTAE OCEAN AREA.; ~ ,:;'j2 i P!I.;~~J,:; J '\', '" .. 1 1. .... '.~',~~ .... I !. .1:'

64 ANNEX VIIIAppendix 11EXAMPLES OF POSSIBLE SCHEDULES OF SHIP MOVEMENTSTO FULFIL THE A-AND B-SCALE OBSERVING PROGRAMMES(Submitted by the JPS)1. There are many ways in which ship movements may be scheduled and any realisticprogramme must take account of the ability of individual ships to remain at sea forknown times and to carry sufficient stores, etc. to conduct the appropriate observations.This paper sets out two examples of possible schedules which are based ondifferent assumptions as to performance and the availability of the number of shipsas compared with the number of stations to be manned. It is hoped that these exampleswill illustrate the need for information on the number of ships to be made availableand their performance characteristics.2. In both examples it is assumed that:(a)(b)(c)A-scale observations will be taken across the Atlantic Ocean from east towest between about 20 0 N and 5°S;B-scale (and smaller scale) observations will be taken in the easternAtlantic throughout the whole period of the experiment (case 1) or will beundertaken for approximately 60 days in the east followed by approximately30 days in the west (case 2) in the areas selected by the Study Group onTropical Disturbances;A cruise speed of 20 km.p.h. (11 knots) is attainable by all ships;(d) No constraint is imposed by the availability of port facilities;(e)A-scale ships with stations in the east Atlantic will remain in the eastAtlantic and use an African port. Those in the west Atlantic will similarlyremain in the west Atlantic and use a Caribbean or South American port;(f) The B-scale ships will use an African port in case 1. For the first 60 daysand the last 30 days in case 2, they will use African and Caribbean or SouthAmerican ports respectively;(g)(h)Within the limitations of (e) above, any A-scale ship will be interchangeablewith any other A-scale ship;Most of the B-scale ships will be similarly interchangeable.

ANNEXVIII653. In example 1 it is further assumed that:(a)(b)(c)(d)The number of stations to be manned is equal to the total number of shipsavailable;All ships have sufficient fuel, technical and other stores to remain at seafor up to 24 days (of which not more than 10 days will be spent on passage);After a maximum period of 24 days at sea, it will be necessary to permit10 days in port for restoring, maintenance and crew leave;It is desired to obtain A-and B-scale observations during identical periods.Figures 1 and 2 illustrate how the limitations imposed by these assumptions,together with those listed in paragraph 2, determine the times that may be devotedto observations. Figure 1 refers to case 1; Figure 2 to case 2. The nearest andmost distant A- scale stations are It and 5 days passage time respectively fromport. The nearest and most distant B-scale stations ~re respectively 1 and 3tdays from port. From Figure 1 (case 1) it can be seen that the first A-scale ship(ship X) is timed to leave port at 00.01 hour on day 1, and reach its station at00.01 on day 6. The other A-scale ships leave port in sequence at the necessary timeintervals, the last one leaving at 12.00 hours on the 4th day. The first A-scaleobservations are taken at 00.01 on the 6th day by which time all positions are occupied.The first B-scale ship (ship K) sails at 12.00 hours on day 1 and arrives onstation at 00.01 on the 5th day as do all the other B-scale ships whieh have sailedin the period up to 00.01 hour on the 4th day when the last B-scale ship (ship L)leaves port. The B-scale ships are allowed 1 day in which to set up their equipmentand the first observation is taken at 00.01 on day 6. All ships may then remain onstation for 14 days plus, for the B-scale ships, one further day for packing equipment.All ships then return to port arriving in sequence between 12.00 hours on day21 and 00.01 hour on day 25. After the 10-day restoring and leave period, A-scaleship Y sails at 12.00 hours on day 31 to the most distant A-scale station. Thisship is followed by others in the fleet, the last one to sail being ship X which wasat the most distant station during the first observation period and now goes to thenearest A-scale position. A similar sequence is followed by the B-scale ships sothat all ships are ready to commence the second period of observations at 12.00 hourson day 36. The programme then continues in this pattern up to day 86 when the lastship reaches port after the third observational period. It is concluded that withinan overall period of 90 days, only three periods, each of 14 days duration, can bededicated to full-scale observations although it should be possible to undertake alimited programme when the ships are on passage outside these three 14-day periods.Referring to Figure 2 (case 2), the programme up to day 60 is identical tothat illustrated in Figure 1 and two 14-day observation periods are possible. Onday 61, the first B-scale ship can sail for a western Atlantic port, followed by theother B-scale ships until the last one sails at 00.01 on day 65. Each ship willrequire 9 days to make the crossing, but when on passage the ships should be able tocarry out an A-scale observational programme. The A-scale ships could similarlymake a short cruise in this period. After this passage it is assumed that it will

66 ANNEX VIIIbe necessary to allow three days in port for re-fuelling and short leave so that allships could then be again on station (the B-scale area now being in the westAtlantic) in time to take the first observations in the tbirdobservational p~riodat 00.01 on day 79. If the third and last period is to be for a full 14 days, thelast ship will not be back in harbour before day 97. The most that can be achieved(assuming at least some of the ships will be available for 97 days) is two 14-dayfull observational periods when the B-scale area is in the east and one 14-dayperidd when the B-scale is in the west, together with a subsiding observationalperiod for the A-scale only, of about 7 or 8 days.4. In Example 2 the following assumptions, additional to those of paragraph 2,are made:(a)(b)(c)(d)50% more ships than stations to be manned are available for the major partof the total period of the experiment;All B-scale ships have sufficient fuel, technical and other stores toremain at sea for up to 27 days, and all A-scale ships for up to 33 days;The time permitted in port for restoring, maintenance and crew leave will berestricted to 5 days;The B-scale ships will be allowed one day for packing and setting up theirequipment when replacing each other;(e) The A-scale ships will leave station 24 hours before replacement. This willresult in a 12-hourly observation being as much as 240 km "off station" oncein every 12-13 days;(f)(g)The total number of ships is divided into 3 groups of which 2 will be onstation while the third is in port or on passage;The passage time to and from station is assumed to be the same as inExample 1.Figures 3 and 4 show ship movements and observational periods which would bepossible on the basis of these assumptions. For case 1 (Figure 3), i.e. when theB-scale area remains in the eastern Atlantic, continuous observation throughout thewhole of the experimental period is possible. The first group of ships commences toleave port at 00.01 on the first day; the second group leaves port from 00.01 onthe 9th day in order that they can be replaced by the first group on the 33rd day.The third group will consequently have to start from port at 00 on the 20th day, andall stations will be occupied from the lOth day. The first group of ships will havetheir last day on stati~n th~ -83r~f day and groups 2 and-3-will leave their stations onthe 99th day, which will be the last day of observation. All stations will thus beoccupied from the lOth to the 99th day, which gives 89 continuous days of observations.


---~~_.. ~1EXAMPLES OFPOSSIBLE SHIP MOVEMENT SCHEDULES FOR THE GARP TROPICAL ATLANTIC EXPERIMENTANNEX VIII 69DAY NtlMBER 2 4 6- 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 100.-l -SCALE I vVVVW7Z7Z7Z/Z/ZZZ7Ay\~AA'M//I / l / / l l Z Z Z l 7f\.NVV\!V\/VI/Z I I I 1777 I 1777N'J\f\I\I'AI '\I\I17ZZZ21117 I II II\J\; "VVV'J7ZZ IZ 1//777 7 1/NVV\l'v '\f\JII 11117111177 /WY1"'1P=ll=>0 SCALEK-v\I\I\lX1Z 7 7 / I 111/17777t>0H-l

ANNEX VIII 71For case 2 (Figure 4) in which the B-scale area is in the E?ostern Atlantic forapproximately the first 60 days and in the llIestern Atlantic farthe remainder of theexperimental period, the ship movements are identical to those in case 1 from thefirst day up to day 59. On day 54 the first group of B-scale ships will leave stqtionand on day 61 the second group ~ill leave station and start the cruise to aCaribbean port where they will join the first group. The third group will not beneeded for the observation period in the western Atlantic and may return to homeports after day 60. The period in the northern Atlantic will start on day 75 whenall ships of groups 1 and 2 will be on station and they will remain there untilday 97, after which they may return to home ports.For both cases 1 and 2 the A-scale observational scheme will be identicalup to day 45 when the ships in the third group in case 2 may leave the stations forhome ports. Of the A-scale ships, groups 1 and 2 are, in case 2, not required on stationbetween the days 60 and 75, but on the latter day they will again be on stationand remain there for the last observational period which ends on day 97.This scheme, in case 1, will provide for continuous observations from day 10to day 99 for both the A-and B-scale. In case 2 an observational period of 50 dayswith the B-scale area in the eastern Atlantic and a further period of 21 days withthis area in the western Atlantic would be realized.If there are N stations, then in case 1 3/2N ships will be needed forsubstantially the whole period of observation whereas in case 2 this number ofships will be needed for the first 60 ooys only. If some ships are able to stay atsea for longer periods (or for the whole of the experimental period) then the maximumnumber of ships required at anyone time would be less.** *

72ANN E XIXAIRCRAFT REQUIREMENTSby Dr. J.P.Kuettner1. The primary use of aircraft will be directed toward C- and D-scale observations to be made within the B-scale ship network. _Theseobservations are concerned with the internal structure and organizationof convective cloud groups, both in the cloud clusters and the· ITC.Use of long-range aircraft to fill gaps in the A-scale network has notbeen considered in this study. The operational techniques to be usedin the exploration of the C- and D-scale are among the more difficulttasks awaiting the ISMG. Nevertheless, some early conclusions can bedrawn at this time.Cloud clusters2. In order to assure good radar coverage and the availability ofsupporting ship data, the airoraft observations must be made within theB-scale network. Henoe this network needs to be suffioiently olose toairfields to provide at least two hours of aircraft enduranoe "onstation" • This implies that the B·-scale area must be generally withinapproximately ~OOO km from airfields. A oompromise is therefore necessarybetween the desire to place the ship network far removed fromcontinental influenoes and the need to procure useful airoraft observationaltime. These oonsiderations are refleoted in the lay-out of theship netwo~k disoussed elsewhere. The actual area of interest, on anyone occasion, will be determined primarily from real-time satelliteinformation (slides illustrate aircraft operations in an ITC clusterand a tradewind cluster during the BOMEX project, based on real-timesatellite data). Sub-areas within the B-network have been identifiedin which the aircraft would be under substantially continuous weatherradar coverage from ships.3. It is anticipated that group flights of 3 aircraft in horizontalformation at levels below 2 km will be needed to probe the boundarylayer in which the primary oonveotive. organization takes place. Theseaircraft eould be conventional propeller-driven or turbo-prop aircraft.In the latter oase they should use their "dash and loiter" oapabilityand fly their out-and-return legs at optimum altitude before descendinginto the area of interest. Sinoe these aircraft must fly in continuousmutual contact in the researoh area, it is important that they havecomparable performance oharaoteristios and oompatible instrumentationwhich may inolude turbulent flux probes (for water vapour, momentumand sensible heat). Furthermore y they should be equipped with radar/transponders, high quality wind·measuring systems suoh as a oombinationof Doppler radar, inertial guidance and Omega navigational systems andwith instrumentation and data-recording systems for standard parameters.

ANNEX IX 734. The other aircraft may cover the levels of approximately 700 mb,500 mb and 200 mb. It is also desirable to obtain high resolution mappingof tne cloud cover and its organization from 15 to 20 km altitude (~lOOmb).The 700-and 500-mb levels could be covered by turbo-prop type aircraft,the remaining levels by jet-aircraft. On-board equipment should includehigh quality wind measuring systems, meteorological radar, temperatureand humidity recordings, radio-altimeters and dropsonde capability.Because of different performance characteristics "vertical stacks" cannotbe maintained, but "time-centre" points can be scheduled.5. Finally, the sea-surface temperature should be systematically mappedfrom low-flying aircraft (about 500 m) equipped with sensitive infra-redscanners. For this, a minimum of 2 dedicated aircraft may be needed. Thetotal requirement would therefore be approximately 9 long-range aircraft.6. Since many cloud clusters form overnight and have a very short lifetime,it may be necessary to mount 2 or 3 missions in short sequence,including night flights. In view of the long duration, crew fatique andmaintenance problems, it can safely be estimated that a significant increasein the number of flight crews will be required.Inter-tropical convergence zoneCITC)7. The exploration of the inter-tropical convergence zone by aircraftcan be conducted on days on which no cloud clusters pass through theB-scale ship network. While the aircraft requirements for each flightmission are similar to the cloud cluster flights, there appears to be nourgent need for repetitive flights in short sequence. Therefore, thenumber of aircraft required for the cloud cluster study is sufficientfor the ITC study.Action proposed8. The TEB is invited to consider the preliminary conclusions of theISMG concerning the aircraft required for cloud cluster and ITC observationswithin the B-scale ship network. The TEB may then wish to give directivesto the ISMG concerning further planning for these aircraft requirements.9. The TEB may wish to explore with the participating countries theavailability of additional long-range research aircraft, as described inparagraph 6. Decisions in this matter require long lead time.

74ANN E XXTERMS OF REFERENCE OF THE SCIENTIFIC AND MANAGEMENT GROUPOF THE TROPICAL EXPERIMENT BOARD1. To perform the necessary work relating to the planning and implementation ofthe GARP Atlantic Tropical Experiment in accordance with the directives of the TropicalExperiment Board, including the preparation of and participation in the:operational and logistical planning;observational programmes;data management and analysis programmes.Members of the SMG are also encouraged to participate actively in the researchprogrammes which will follow on the basis of the GATE data.In carrying out the functions mentioned above it is essential that liaisonbe maintained with the WMO Secretariat and the JPS in order that the overall planningtake fully into account the scientific objectives of GARP as developed by theJOC.2. To maintain liaison at the working level with experts designated for thispurpose by each participating country and by interested organizations so as to keepupt6 date the information on national and international plans for and contributionsto the Experiment, and to assist in the integration of these plans and contributionsinto a co-ordinated effort.3. To make the necessary proposals and to take appropriate action relating tothe arrangements for the conduct of its work.4. To submit short but informative progress reports every three months to theTropical Experiment Board.5. To prepare the provisional agenda dnd supporting documentation for sessionsof the Tropical Experiment Board in consultation with the chairman of the TropicalExperiment Board, the Secretary-General of WMO and the Director of JPS.

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