DV Anderson, JP Bruce,* U. Sporns* and G. Ii Rodgers Ilniuersity of ...


DV Anderson, JP Bruce,* U. Sporns* and G. Ii Rodgers Ilniuersity of ...

MNTER RESEARCH ON LAKE ONTARIO 187made trial operational ice reconnaissance flights over Lake Superior, the NorthChannel, Georgian Bay and Lake Erie during March and April 1960 in prepa.rationfor opening of Lakes navigation (Archibald et al. 1960). In the winter of 1960-1961a program of 11 aerial reconnaissance flights was followed. Ship observations forfour of these flights were taken by the C.M.S. Grenuille.The Porte Dauphine and the Grenuille made observations of ice in the eastoutlet basin of Lake Ontario on the same days as the flights so that surface informationon water temperature, winds, ice structure, etc., was available for correlationwith the aerial inspection.The distribution and character of the ice observed by the ice observer techniciansin January 1960 are shown in Figures I and 2. Figure I shows conditionsobserved from the Porte Dauphine, and Figure 2 illustrates the aerial observations.These maps indicate the maximum extent of ice cover during the winter1959-60. Whiie the two charts differ in detail, the main features are clear. Somepancake and slush ice was found in the outflow waters on the Niagara River andsouth of Prince Edward County, but otherwise the main body of the lake was free ofice. At the margins, only a few hundred feet of broken ice recurred on the southshore and much Iess on the north shore.The detailed surveys of the eastern outlet basin indicate that in January aship moving from Main Duck towards WoUe Island would have encountered eight tonine-tenths coverage of young ice several inches thick. However, by February 24conditions had improved to the extent that only five-tenths of pancake ice one-halfto 1 inch thick would be encountered on the trip. Along the shores though and closeto the islands, fast ice of 3 to more than 16 inch thickness would be encountered.While air temperatures were about 3 degrees Fahrenheit above normal in February1960 at shore stations around Lake Ontario, they were still well below freezing(25T') and thus the less extensive ice in February must be attributed largely to themovement of ice out of the eastern outlet basin into the lake and its dissipationthere. In support of this view, the mean wind speed for February at surroundingshore stations was 18 per cent higher than normal and included several extendedperiods (Feb. 5-6, l7 -18, 24) of strong easterly winds.The most extensive ice cover in Lake Ontario in the 1960-61 winter was encounteredin February. This is illustrated in Figures 3 and 4, showing the observationsof the Grenuille cruise of Feb. 6-9, 1961, and the aerial reconnaissanceFeb. 15, 1961. A key to ice symbols used is given in Figure 5.In order to study and forecast the formation of ice on lakes, it seems to bemost logical to evaluate those terms in the energy budget that contribute most toenergy loss from the lake in winter months and try to characterize these terms ofthe energy budget by readily available meteorological parameters. The magnitudesof the various terms (monthly means) in the energy budget for Lake Ontario havebeen given by Rodgers and Anderson (1961). They show that energy loss due to conductionof sensible heat to the atmosphere, and energy loss due to evaporation fromthe lake are about equal in magnitude during the winter months. Almost all of thisenergy is derived from heat storage. The net back radiation varies Iittle throughoutthe year and is almost equal to the solar radiation incident to the water surfaceduring the months of January and December on cloudy days.The formation of ice would naturally be favored by shallow water having asmall heat storage, and by low air temperature, providing a large gradient for theheat flux from the water to the air for the conduction of sensible heat to the atmosphere.Another meteorological element favoring heat loss is a high wind speedwhich will enlarge somewhat the effective interface between the water and the airand therefore allow for greater flux of heat from the water to the air, as well asmore rapid distribution of heat by turbulent eddies. Energy loss from the water by

ILAKE ONTARIOSHIP ICE RECONNAISSANCE20-24 JANUARY 1960IIFig. 1. Ice chart of Lake Ontario from ship reconnaissance, January 1960.a'

LAKE ONTARIOAERIAL ICE RECONNAISSANCE2I JANUARY 1960-l_A540 60Y2oSL20lC__l-q_ a1000 60sL40Y44" .8A440 80Y20SLla# *,* ilw-sE srRrNGsCOMPACT SLUSH APPROX 70'NORTHWARD ALONG SOUTHSHORE FROM OSWEGO TOGRIMSEY2A200 sLI80.79"Ice chart of Lake Ontario from aerial reconnaissance, January 1960.

LAKE ONTARIOSHIP ICE RECON.IAISSANCE6-9 FEBRUARY 196IFig. 3. Ice chart of Lake Ontario from ship reconnaissance, February 1961.

IIiLAKE ONTARIOAERIAL ICE RECONNAISSANCEI5 FEBRUARY 196IFig. 4. Ice chart of Lake Ontario from aerial reconnaissance, February 1961.

D. V. ANDERSON ET AL.METEOROLOGICAL BRANCHDEPARTMENT OF TRANSPORT. CANADAGotcEtTnAT I 0r AGE rcE 0r LltD 0RtgtlflxTiTfl _^ A L Icebergs (rrny)t.'.'.'.'.'.'.'.'.'.1 < O. 1 coveraretllll:l:i - donlnant, secondaryA Icebergs 6ter,1l.'.'r'i.lO.1 to 0.5 coveraSe s, - SlushNY - Youg lceBergy blts andf - lflnter Ice - grorlers (aany)llllllllO.S to 0.8 coverage PI - Polar IcettttlttlBergy bits and.. ^ grorlers (fcr)N\\\\O.8 to 1.O coverage Examples:t\\\\r,. A ,.tc.IlX XN 1.O coverage (no t.tcr)EJ'J'xJlKEY TO ICE SYMBOTSPuDDLESsI ,r :.P'rATER FEATURESCOICEITRATIOI 8Y 3tzE +.tn crackCnPdnt,n2,n3dominant condltlonLead==-n, - tenths of slush, brash Tenths of 1ce coveredand block 1f not frozen or rottenn, - tenths of snall and- nedlun floesn".- tenths of glant floes- and ficldF - Frozenn - RottennnO O@UIDERCASTPolynyaTo.P00 nA PIYExanples: Pd'Pd'Pd' 3 F X-.- -'-'t -) r,ta 1tsRafted tc€T[tcxtEss 0F sEA tcE ArD srof EoutDAIYRldged lce t,S, xhere n '- nc.tcttInft.(nornRumocks-l-t* Radar---- - AssutredErmples: t,S, ctc.oooo *--- L1nlt of5 2estfnaieAdata,$ynbols used for Recordin4 the Ve.ious fc", Sror, nd 'atcrF.aturct.Fig. 5. Key to ice symbols.

MNTER RESEARCH ON LAKE ONTARIO 193. evaporation depends of course on the vapour pressure gradient between the water. and the air, and wind speed. Next to temperature, the mean monthly wind speedseems at first sight, therefore, to be one reasonable index of energy loss from theu'lake during the winter months. Furthermore, as wiII be seen Later, higher windspeeds seem to be related to greater cloud cover during the winter months andtherefore reduce solar radiation incident to the water surface by about one-half ona cloudy day, in comparison with a clear day. However the mechanism of freezingof a large lake is poorly understood, and it may be that wind induced mixing of surfacewaters and warmer deeper waters will idhibit freezing, so that increasedenergy loss is counterbalanced, up to a point, by entrainment of deep water.Since the other lakes freeze over and Lake Ontario normally does not, onewonders how frequently Lake Ontario does freeze. Thanks to a meteorological observerof the Department of Transport (Ur. e. W. Hooper) and a former employeeof the Ontario Car Ferry Company (Mr. R. S. IMartin of Cobourg), we learned ofthe little known occasion during the rvinter of 1933-34 when the lake did freeze overto a thickness of half a foot or so. Data were compiled for this rvinter from Toronto,Kingston and Rochester and were compared with long-term averages from thesame locations. The results are shown in graphical form in Figure 6. The moststriking feature is the great reduction in average monthly temperature, especiallyfor February. The wind on the other hand was average, and so no conclusion canbe drawn about its role in ice formation.This winter of 1933-34 was the only winter from about 1908 onward inwhich the take did freeze, according to information from Mr. J. A. Sauve of theCanadian National Railways, who was also connected with the Ferry Company. Wehave an unconfirmed report that the lake froze in the winter of 1892-93. Thus itmay be supposed tentatively that the lake will freeze over about once every fiftyyears, although long term climatic warming or cooling may greatly modify thisperiod.The winter data for 1959-60 and 1960-61 will be used shortly in energybudget calculations for the two winters, but the 1961 data were not readily availablein time to complete such calculations for this paper.COMPARISON OF OVER-LAKE AND OVER-LAND CONDITIONSa.In the solution of many lake problems we will not have, in the foreseeablefuture, enough direct observational data. Thus a good relationship between over-Iake and over-land conditions will permit use of shore station data in solution ofsuch problems. Comparisons have been made here between the values obtained inthe ten winter cruises of 1959-60 and 1960-61 with short-term and long-term meanland data on vapour pressure, air temperature, wind speed and cloud cover,A summary of the results is given in Table 1. As far as the wind factor isconcerned, the mean ratio of lake wind to land wind of 1.61 obtained in the shipdata is very similar to the spring ratio obtained by Bruce and Rodgers (1959) usingTable 1. Ratio (n) = #i*#over Lake Ontariofor the Winter SeasonParameter R Range of RVapour PressureDry BuIb Temp.Wind SpeedCloud Cover1.161.101. 611.000.96 - 1.300.84 - 1.311.13 - 2.300.34 - 1.36

194 D. V. ANDERSON ET AL.48,46s

MNTER RESEARCH ON LAKE ONTARIO195\50o=48tcos= ++t FotNOV 1959 DEC. 1959xta.\Y\- -DATA FROM SURROUNDINGLAND STATIONS (MEANMONTHLY VALUES)/ AVERAGE SURFACE WATERFEB. t960 MAR. 1960TEMPERATURE oF\ \ x--{_ ___ _xq26E=24 l{SzzdNroS,'S- t6x...\24-/ aVERAGE DRY BULB r€MP1. ovER THE LAKE OF AV SAT, VAP PRESSUREIIUllJ=6sQqs2sdo'---->'>-OVER LAKEVAPOUR PRESSURESFC WATER TEMPCLOUO COVER(TENTH OF SKY)Fig. 7. Compalison of meteorological elements over Lake Ontario and at shorestations.1959-60.the lake fall between the water and Iand air temperatures except for March, and thewind speeds are consistently higher.Mean monthly water temperatures of the lake surlaces were obtained fromthe cruise data for the two winters by planimetry. The results were not significantlydiflerent from the mean water temperatures presented by Millar (1952), asshown in Figure 9, although the temperatures in the deepest part oI the lake in thesoutheast, as observed in the past two winters, were slightly higher (1-2"F) thanMillar's charts indicate. Volume average temperatures are given in Figure 10.

196 D. V. ANDERSON ET AL.o\=\"FS$H504846444240NOV 1960 DEC. t960 JAN. t95l FEB. 196l MAR. t96l APR. t96lE=S38363432302a26AVERAGE SURFACEWATER TEMC OF\ AVERAGE DRY BULBl rTEMP OVER LAKE\/242?t iu i3e"5ss?ot8l6t4t2.')'-'.../'AVERAGE WINO SPEEDOVER THE LAKE\*x/--l-"_//wtND SPEED*stH:sls()iqs{stoI42olo 20 30 ro 20 30 ro 20 30 lo 20 30 lo 20 30 to 20 30Fig. 8. Comparison of meteorological elements over Lake ontario and at shorestations,1960-61.The close agreement of two years' data, along with the agreement of recent surfacetemperatures with those of Millar, indicates that these curves are reasonablyaccurate PreliminarY estimates.CONCLUSIONIt has been amply demonstrated over the past two years that valuable datacan be collected from well-founded ships on Lake Ontario in the winter.

MNTER R,ESEARCH ON I"AKE ONTARIO19?lll'\ \ \.-rgse\\Fig. 9. Average surface temperatures of Lake Ontario during winter months, excludingeast outlet basin.7-5-4544434?lrlj5-4-3-4l403938372-3635OCTOIEi f,OVEIlfR ' OSSCTSER JAIU RY F€'RUAiY' XAiCN AFRIL ' IAYFig. 10. Volume average temperatures of Lake Ontario during winter months, 1959-61.

198 D. V. ANDERSON ET AL.Some of the data collected and preliminary analyses of these have beenpresented. Future work will be concentrated on studies to permit,forecasting ofice formation, movement and dissipation, and in clarifying the relationships betweenover-lake and over-land observations to permit use of the much more extensiveland data in determining such things as winter evaloration rates and windset-up factors.ir t."tACKNOWLEDGMENTS .The work reported herein is part of a program of Great Lakes researchfinanced by the Ontario Department of tands and Forests,, the National ResearchCouncil of Canada, the University of Toronto, and the Canada Department of Transportin association rvith other Canadian agencies.. REFERENCESAnderson, D. V. 195?. Geophysics research vessel for Great Lakes. Special Report to OntarioDept. Lands and Forests.Anderson, D. V. 1960, Canadats Great Lakes research progr€rmme. The Conservationist,State of New York Conservation Dept., Aug.-Sept.Archibald, D. C., M. N. Monsinger and E. Stasyshn. 1960. Aerial sea ice observing and reconnaissanceprogramme in the Great Lakes, 1960. Meteorological Br., Canada Dept.Transport, CIR 3361, TEC-328.Bruce, J. P. and G. K. Rodgers. 1959. The water balance of the Great Lakes system. AAASymposium on the Great Lakes Basin, Chicago, Dec. 1959.Millar, F. G. 1952. Surface temperatures of the Great Lakes. Jour, Fish, Res. Bd. Canada'9: 329-376.Rodgers, G. K. and D. V. Anderson. 1961. A preliminary study of the energy budget of LakeOntario. Jour. Fish, Res. Bd. Canada, in press.Shenfield, L. and D. F. A. Slater, 1960. The climate of Toronto. Meteorological Br., CanadaDept. Transport, CIR 3352, TEC-327.Smith, S. H, 1956. Limnological surveys of the Great Lakes - Early and recent. Trans. Amer.Fish. Soc., 84: 409-418.Thiele, E. I{. 1960. The ice problem. Paper presented at Conf, on Shipping and NavigationProblems of the Great Lakes and St, Lawrence Seaway, Princeton University, Princeton,N. J., Jan. 19-20, pp 47-62.verber, J. L. 1955. Bibliography of Physical Limnology, 1781-1954. Rpt. Invest. 25, Div, ofShore Erosion, Dept. of Natural Resources, Columbus, Ohio.tlt'Igl

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