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178gravity waves were mostly generated in the middle troposphere and that waves which reachedstratosphere were propagating upward.Data BaseIn the present study the VHF Radar at Gadanki (13.48º N, 79.18º E), a tropical station isused to study the gravity wave activity in four typical months representing different seasonsnamely Pre Monsoon (March - May), Monsoon (June - September), Post Monsoon (October -November) and Winter (December-February) seasons. The observations were taken during 09-12 April 2001(Pre Monsoon), 19-22 July 1999, 16-19 July 2001 (Monsoon), 16-19 October2000, 26-29 November 2001 (Post Monsoon), 22-25 January 2002 (Winter). Data is collected forthree days in each season at 1000 -1600 LT, 2000 – 2030 LT, 0030 – 0100 LT, and 0500 – 0530LT on each day. The Radar antenna beam was pointed towards 6 beam directions viz., East,West, North, South inclined at an angle of 10º from the Zenith and along two Vertical beams,one in E-W polarization and the other in the North-South polarization. For all the six beamdirections, mean radial velocities observed in 3.6 min interval provided the original data. Thereceived echo signals were sampled at height resolution of 150 m during 19-22 July 1999, 16-19 July 2001 and 22-25 January 2002 and 300 m height resolution during 16-19 October 2000and 09-12 April 2001.Results and DiscussionsFigure 1 shows the background wind information in different seasons on a typical day. Inpre monsoon season zonal winds are westward from 2 km to 6 km, eastward from 6-15 km andagain westward above 14 km. During Monsoon season because of Jet streams the Zonal winds aremaximum ~ -40 m/s around 17 km and these winds are easterlies above 9 km. During postmonsoon season the zonal winds are almost westward with less magnitude compared to otherseasons. In winter season the zonal winds are westward. In pre monsoon season meridional windsare northward up to 16 km and above that these winds are southward. In Monsoon season up to 6km southward and above 6 km northward. During Post monsoon and winter seasons meridionalwinds are towards northward direction. In all the seasons vertical velocities are small with upwardand downward oscillations.Figure 2 represents the time series plot of Zonal velocity in different seasons for onetypical day in the troposphere and lower stratosphere during the six-hour period of observationstarting at 1000 hrs LT. Above 10 km the wind disturbances are more prominent and while goingupward the magnitude of the disturbances are more, this will imply wave motions that arevertically propagating and it is evident from the figure that, wave like structure exists in the timeseries with a clear phase variation and different characteristic periods and also it is clear that thesource mechanisms are originating in the lower atmosphere. In order to calculate the frequencyspectra of gravity waves the zonal velocities were taken and they were subjected to the FFTanalysis. Figure3 shows frequency spectra for zonal velocity on 18 th July 2001 during 1000-1600hrs observations. From this observations 5 harmonic components were determined and thecorresponding time periods are 2 Hr 20 min, 55-46 min, 20-30 min, 20-15 min and 8 min. Themaximum amplitude of these waves is 3 m/s. According to Tsuda et al., 1994, the periods rangingfrom 5 minutes to 2 hours are mainly due to the large wind shears, which are mainly observedduring jet streams. The observed periods near the jet streams in the present study (around16 –17 km) lie within the periods as reported by Tsuda et al., 1994. Previous studies revealed thatgravity waves of such wave periods exist over this Radar site [Nagpal et al., 1994; Dutta et al.,1999]. During pre monsoon and monsoon season the wave activity is more dominant.Figure 4 represents vertical wavelength and propagation direction of gravity waves areobtained using Hodograph analysis. On 18 Jul 2001 Zonal velocity has been taken on X –axis andMeridional velocity has been taken on Y-axis for hodograph analysis from 10.2 -20.1 km during
1100-1200 hours. From this plot 6.3 km vertical wavelength of waves are dominant with clockwisedirection. If the rotation of the waves is in clockwise direction it represents that the waves arepropagated upward. If it is anticlockwise direction, it represents that the waves are propagateddownward. So this plot clearly shows the upward propagating waves means the source region is inthe lower atmosphere. The downward zonal momentum flux shows higher values on 18th July2001. Meridional momentum flux is southward from 7-13.5 km and northward from 13.5-17 km.Zonal and meridional variances are increasing with increasing height and reaching maximumvalues at higher heights.ConclusionThe seasonal variation of gravity wave activity in the troposphere and lower stratospherebased on wind velocity observations made with the Indian MST Radar for about 3 days in a eachseason, continuously for six hours duration April 2001-2002 January have been analyzed. Bytaking this data we have examined the gravity wave activity in the troposphere and lowerStratosphere. Zonal, Meridional and vertical velocity fields exhibited motions with periods rangingfrom a few minutes to hours with propagating character.AcknowledgementsThe authors are thankful to the UGC-SVU Center for MST Radar Applications, S.V.University, Tirupati and National MST Radar Facility (NMRF), Gadanki for providing necessaryfacilities to carry out this work. One of the author s I.V. Subba Reddy is thankful to the AdvancedCentre for Atmospheric Sciences, Department of Space, Govt. of India and also to the Council ofScientific and Industrial Research (CSIR) for providing Junior Research Fellowship and SeniorResearch Fellowship respectively.ReferencesDutta G, B.Bapiraju, P.Balasubramanyam, H.Aleem Basha, VHF Radar observations of gravitywaves at a low latitude, Ann. Geophysicae., 17, 1012-1019. 1999Dhaka, S. K, P.K.Devarajan, Y.Shibagaki, R.K.Choudhary, S.Fukao, Indian MST Radarobservations of gravity wave activities associated with tropical convection, J. Atmos. Solar-Terr. Phy., 63, 1631-1642, 2001.Dhaka, S. K, R. K.Choudhary, S. Malik, Y.Shibagaki, M. D. Yamanaka, S. Fukao, Observablesignatures of a convectively generated wave field over the tropics using Indian MST radar atGadanki (13.48º N, 79.18º E), Geophys. Res. Lett., Vol. 29, No.18, 2002.Fritts, D.C., M.A. Geller, B.B.Balsley, M.L.Chanin, I.Hirota, J.R.Holton, S. Kato, R.S. Lindzen,M.R.Schoebert, R.A.Vincent and R.F.Woodman, Research Status and recommendations fromthe Alaska Workshop on gravity waves and turbulence in the middle atmosphere, Bull. Am.Meteorol. Soc., 65, 149-159, 1984.Fritts, D. C., and Z.Luo. Gravity wave excitation by geostrophic adjustment of the jet stream.Part I: Two-dimensional; forcing, J. Atmos. Sci., 49, 861-697, 1992.Fritts, D. C., and G. D. Nastrom, Sources of mesoscale variability of gravity waves, II, Frontal,Convective and Jet stream excitation, J. Atmos. Sci., 49, 111-127, 1992Nagpal, O.P., D. Praveen Kumar and S.K. Dhaka., Characteristics of tropospheric gravity wavesby the Indian MST Radar: ST mode operation, Indian J. of Radio and Space Physics, 23, 6-11,1994.Nastrom, G.D., and D.C.Fritts, Sources of mesoscale variability of gravity waves, I:Topographic excitation, J. Atmos. Sci., 49, 101-110, 1992.Tsuda, T., Y.Murayama, H.Wiryosumarto, S.B.Harijiono, and S. Kato, Radiosonde observationsof equatorial atmosphere dynamics over Indonesia, 2, Characteristics of gravity waves, J.Geophys. Res., 99, 10,507-10,516, 1994179
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MST10Tenth InternationalWORKSHOPOn
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MST 10 Group PictureMay 15 th , 200
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TENTH INTERNATIONAL WORKSHOP ON TEC
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Table of ContentsPREFACE ..........
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I.2.18 FURTHER OBSERVATIONS OF PMSE
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I.3.27 NEW MST RADAR METHODS FOR ME
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I.4.19 STUDY OF A MESOSCALE LAND-TO
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I.5.502 AN ATTEMPT TO CALIBRATE THE
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PrefaceMST10The Tenth International
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and the local organizing committee,
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The operational aspects and recent
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To improve the understanding of dyn
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Improving MST radar resolution by u
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latitudes, arguing that the former
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Report on Session I.3 “Winds, Wav
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Turbulence.The session then moved i
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Report on Session I.4 “Meteorolog
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Multiple Antenna Profiling Radar (M
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Report on Session II “Novel Persp
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synchronized by GPS and connected v
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The highly positive response of the
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10th International Workshop on Tech
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10th International Workshop on Tech
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Session I.1: Radar scattering proce
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⎡7800 ∂q⎤(3)⎢ 15500q⎥M =
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Figure 2 compares profiles of ω B
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Figure 1: Data from the MST radar a
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Ri =shear2ωB22⎛ ∂u⎞ ⎛ ∂v
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Meridional (deg)1050−5−10Echo P
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Subarray Configuration, Capon Metho
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Fig. 2 PMSE plot (SOUSY Svalbard Ra
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VHF radar interferometry had shown
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turbulence. From Figures 1 and 2, i
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SummaryFrom the aspect sensitivity
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a specific range. In this work, syn
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P C(dB)(a) Echo Power60504030200.70
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most occidental area of South Ameri
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Quegan, 1992). It should be useful
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measurements, is shown in figure 1(
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The present observations thus empha
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RECENT OBSERVATIONS OF E REGION FIE
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measured spectra in order to separa
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drifts at E and F regions heights b
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• Are characterized by type II ec
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The main parameters that could be o
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THE ROLE OF UNSTABLE SPORADIC-E LAY
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(σ H / σ P )E y (where σ H and
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STUDY OF A LOW E-REGION QUASI-PERIO
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100 m/syrFigure 4: Geometry of the
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Where the notations carry same mean
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Where dx/dt and dy/dt are the veloc
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non-negativity of the image is prio
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spectrum corresponding to the backs
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The Artigas and Machu-Picchu Statio
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Arguments against the second altern
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Extension of the Kolmogorov spectru
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volumeESRvolumeSSRSSR SSRESR ESRSSR
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individual particles in a statistic
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Anomalous spectraTalkner [4] studie
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To observe the E region FAI echoes,
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matter daytime or nighttime and are
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two sub-arrays, each sub-array made
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4. SummaryHere we describe a radio
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Figure 1. E-region DPS4 spectra, ri
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effects. It is therefore plausible
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Page 135 and 136: electric fields map along the geoma
Page 137 and 138: SNR condition is always difficult a
Page 139 and 140: Figure-4 Power spectrum plots of a
Page 141 and 142: As we show below, Jicamarca offers
Page 143 and 144: particularly during daytime counter
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Page 147 and 148: PMSE is more easily interpreted as
Page 149 and 150: ResultsTemperature climatology• s
Page 151 and 152: Simultaneous PMSE and NLC observati
Page 153 and 154: ResultsSeasonal variationMSE are no
Page 155 and 156: Figure 2: MSE parameters as functio
Page 157 and 158: Session I.3: Winds, waves and turbu
Page 159 and 160: poor. It was shown that poor perfor
Page 161 and 162: The use of diffraction pattern simi
Page 163 and 164: F 13 (ξ x ′) = (1 − cos 2ψ N)
Page 165 and 166: Figure 3: (a) Baseline length depen
Page 167 and 168: 3. ResultsFigure 1 shows the amplit
Page 169 and 170: variability.Figure 4 shows the aver
Page 171 and 172: Figure 1. Period-time amplitude wav
Page 173 and 174: the 12-h and 24-h periodicities in
Page 175 and 176: winds and variances at altitudes 70
Page 177 and 178: similar correlation with larger mag
Page 179 and 180: of the refraction index are not equ
Page 181 and 182: Fig. 8. Zonal wind (top) and temper
Page 183: STUDIES ON ATMOSPHERIC GRAVITY WAVE
Page 187 and 188: STUDIES ON WINDS AND MOMENTUM FLUXE
Page 189 and 190: 3.4 Monthly variation of momentum f
Page 191 and 192: DEEP PENETRATIVE CONVECTION AND GEN
Page 193 and 194: ly changes direction with time with
Page 195 and 196: 189
Page 197 and 198: 191
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Page 201 and 202: These two last relations are the on
Page 203 and 204: 3.2.1 From v ′2 to ɛ kThe questi
Page 205 and 206: 5.2 Frequency distributionsSeveral
Page 207 and 208: ReferencesAlisse J.-R. and C. Sidi.
Page 209 and 210: Röttger J. and C.H. Liu. Partial r
Page 211 and 212: Specular reflection is negligible f
Page 213 and 214: −0.5C n2 Distribution (PROUST & S
Page 215 and 216: the beamwidth, α is the zenith ang
Page 217 and 218: this latitude in late April). Surfa
Page 219 and 220: Fig. 1. Median (upper) winds and (l
Page 221 and 222: Fig.1. Lines of constant radial vel
Page 223 and 224: which have not yet been considered
Page 225 and 226: is calculated from the radiosonde t
Page 227 and 228: Figure 3: Time-altitude cross-secti
Page 229 and 230: Absorption of cosmic noise is cause
Page 231 and 232: Incoherent scatter spectracompared
Page 233 and 234: variations of spectral widths, refr
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Figure 1. Diurnal variation of Turb
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further experimental test of the ST
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waves can be observed more clearly
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winter and a minimum in summer near
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The main recently assumed mechanism
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Figure 2. Statistics of numbers of
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LIDAR OBSERVATIONS OF MIDDLE ATMOSP
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latitudinal dependence of the seaso
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APPLICATION OF THE DUAL-BEAMWIDTH M
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Figure 2: Mean zonal and meridional
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JLKLLK/ILIL6II/G/II/G/LEODFLK/LO/DD
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The monthly diurnal mean of horizon
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Session I.4: Meteorological Phenome
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Integration of the VHF wind profile
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Figure 1 : Map of the Lago Maggiore
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precipitating clouds, the cyclonic
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Eyewall(a)(b)(c)(d)Fig. 3: Radius-h
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as low as 0.55. The Piura 50-MHz ra
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place features in the profile with
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• Period 1 (June 1-10): SCCs exis
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Sumatera occurs by stratiform cloud
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very interesting to note the double
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20(a) Convective Region(b) Transiti
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Typhoon LekimaFig. 2 Typhoon Lekima
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Fig. 5 Passage of typhoon Hayan on
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the 50 cm 2 sensor head, enabling t
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22 June 2000 23:22:23 - 23:24:20 at
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the time-height section of a convec
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Thurai, M., T.Iguchi,T. Kozu, J.D.E
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There are two main mechanisms which
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Horel, J.D. and Cornejo-Garrido, A.
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estimating two independent and redu
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RASS THETA (K) RASS v-component (m/
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Surface winds usually range from 10
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weak (maximum of 5 m s -1 ) and the
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The vertical component from the VTB
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Figure 8 shows the profile of virtu
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2 3D ( , ) ( ) ( ) ˆ ( ) ˆp∆ xm
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presented in Praskovsky et al. (200
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In Fig. 2 a sketch of a mountain le
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In Fig. 8 the lamina is aligned on
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Figure 1: composite day (13 days) o
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virtual sensible heat fluxes ( Wm-2
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3. Characteristics of precipitation
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Fig. 3: Horizontal distribution of
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3. Results and discussionUHF profil
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Figure 4. Monthly variation of slop
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system with two receiving antennae,
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cycle of precipitation. Figure 3(a)
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Histogram of Zonal Velocityh=5.13 K
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5. Summary of results and concludin
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the two nearby major cities, Chenna
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Boundary layer height, km32.521.5(a
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Figure 1:Data from the MST radar at
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spectral processing. In this partic
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3. Results and discussionIn the pre
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4. SummaryAn attempt has been made
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The purpose of this study is to exa
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Figure1. Three-day average of momen
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3. The improved method to estimate
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But in case of period until 1800 UT
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Session I.5: Operational Aspects an
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The profilers of WINDAS weredesigne
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NOAA, 1994 : Wind profiler assessme
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FIRST RESULTS OF THE BOUNDARY LAYER
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Figure 3. Pulse Design Diagram to s
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MOVEABLE UHF/S-BAND PROFILER/DISDRO
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one-minute Z values determined from
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TOWARD A MULTISENSOR GROUND BASED R
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3. Cloud Evolution Case StudyOn the
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DEVELOPMENT OF A DIGITAL RECEIVER F
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Experiment 1 Experiment 2IPP 999Km
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ELECTRONIC DIGITAL BEAMFORMING IMPL
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The main element of the unit (figur
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.ON-LINE ADAPTIVE DC-GROUND-CLUTTER
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esulting in a widening of the bandw
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ON THE RADIATION EFFICIENCY OF COCO
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Table 2: Experiment #1 results, Tra
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A NEW NARROW BEAM MF RADAR AT 3 MHZ
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Off-zenith beams towards N, S, E, W
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95ALWIN VHF radar: signal powerdB80
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ANTENNA BEAM VERIFICATION USING COS
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Figure 2: A 45 MHz reference sky te
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AN ATTEMPT TO CALIBRATE THE UHF STR
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is at 4.7 km, but in the first 4-ga
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QUALITY CONTROL FOR DOPPLER WIND PR
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The resulting moments are subjected
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SOUSY RADAR AT JICAMARCA: SYSTEM DE
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NEControl andcomputer roomCompCoute
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THE EQUATORIAL ATMOSPHERE RADAR:SYS
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Table 1: Specifications of the EAR
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VHF ATMOSPHERIC AND METEOR RADAR IN
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ased upon a geotechnical engineerin
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VORTICAL MOTIONS OBSERVED WITH THE
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interpolation from the original gri
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A NEW MINIRADAR TO INVESTIGATE URBA
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e eliminated to analyze correctly t
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Session PWG 1: System Calibrations
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Session PWG 2: Data Analysis, Valid
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• the time series vectors x(k) of
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Fig. 4: reflectivity of the hydrome
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Session PWG 3: Accuracies and Requi
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Session PWG 4: International Collab
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Session II.E: NOVEL PERSPECTIVES AN
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2 Proposed AlgorithmReceived signal
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N#4E-1-16E1A1#1#2A-1-1C1#3C-1-19Fig
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of conventional DCMP, with which th
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applying the directional constraint
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while for a beam of finite width, t
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In order to make the process more q
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WHAT IS TURBULENCE SEEN BY VHF RADA
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Enhanced resolution applyingpulse s
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Beckmann, Spizichino, 1964Fig. 8 Po
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Fig. 11 Plots of temporal variation
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Fig. 14 Distributions of phase cent
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Hocking, W.K., Radar studies of sma
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THE STRUCTURE FUNCTION-BASED APPROA
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{ Ui( t), Vi( t), Wi( t)} = { Ui ,
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161). Assumption 2H: the instantane
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Only the second order SF are consid
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fluctuations umk( t ) along the bas
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VHF PARASITIC RADAR INTERFEROMETRYF
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• All the costs of transmitter pr
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Figure 2: Example of range-azimuth
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Target Altitude, km1009080706050403
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ReferencesGriffiths, H. D., A. J. G
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Participants ListAvery, James P.Uni
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Hysell, David L.EAS/Cornell Univers
Page 491 and 492:
Silva, Robert R.ATRADAustraliarsilv
Page 493 and 494:
AAdachi, A. .......................
Page 495:
TTabary, P. .......................
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