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6. ConclusionIn this paper, some results of studies of climatology of internal gravity waves (IGWs) inthe middle and upper atmosphere are described. MST and MF radars and ground-basedoptical observations give information about seasonal and interannual changes of the meanwinds and IGW variances. Low-orbit satellites receiving GPS signals may givedistribution of zones of increased IGW and turbulence intensity and wave generation.Numerical models allow studying sensitivity of general circulation of the middleatmosphere to global inhomogeneity of IGW sources observed with radars and GPSsatellites. Combined radar, optical and satellite measurements are essential for betterunderstanding wave dynamics of the atmosphere.Acknowledgements. This study was partly supported by Russian Basic ResearchFoundation. COMMA core version was provided by the Institute of Geophysics andMeteorology, Cologne University. GPS/MET data had been provided by UCAR troughDrs. C. Rocken and S. Sokolovsky.References.Alexander, M. J., Tsuda, T., Vincent, R. A., 2002. Latitudinal variations observed ingravity waves with short vertical wavelengths, J. Atmos. Sci., 59, 1394-1404.Frohlich K. , A. Pogoreltsev, and Ch. Jacobi, Numerical simulation of tides, Rossbyand Kelvin waves with the COMMA-LIM model, Adv. Space Res., in press, 2003Gavrilov N. M., A. H. Manson, and C. E. Meek, Climatological monthlycharacteristics of middle atmosphere gravity waves (10 min - 10 hr) during 1979 - 1993 atSaskatoon, Ann. Geophys., 13, 285-295, 1995.Gavrilov, N. M., S. Fukao, and T. Nakamura, Gravity Wave Intensity and MomentumFluxes in the Mesosphere over Shigaraki, Japan (35° N,136° E) During 1986 - 1997,Ann. Geophys., 18, 834 – 843, 2000.Gavrilov, N. M., Ch. Jacobi, and D. Kurschner, Short-period variations of ionosphericdrifts at Collm and their connection with the dynamics of the lower and middleatmosphere, Phys. Chem. Earth, C 26, 459-464, 2001.Gavrilov, N. M., K. Shiokawa, and T. Ogawa, Seasonal variations of medium-scalegravity wave parameters in the lower thermosphere obtained from SATI observations atShigaraki, Japan, J. Geophys. Res., D107, 10.1029/2001JD001469, 2002.Gavrilov, N. M., D. M. Riggin and D. C. Fritts, Medium Frequency Radar Studies ofGravity Wave Seasonal Variations over Hawaii (22 N, 160 W), J. Geophys. Res., D109,in press, 2003a.Gavrilov N. M., D. M. Riggin, and D. C. Fritts. Interannual variations of the meanwind and gravity wave variances in the middle atmosphere over Hawaii, J. Atmos. Solar-Terr. Phys., 65, in press, 2003b.Gavrilov, N. M., N. V. Karpova , and Ch. Jacobi. Morphology of atmosphericrefraction index variations at different altitudes from GPS/MET satellite observations, J.Atmos. Solar-Terr. Phys., 65, in press, 2003c.Gavrilov, N. M., A. I. Pogoreltsev, and Ch. Jacobi, Numerical modeling of influenceof inhomogeneous gravity waves on general circulation of the middle atmosphere, Atmos.Oceanic Phys., Izvestia of Russian Acad. Sci., 39, in press, 2003d.Nastrom, G. D., Hansen, A. R., Tsuda, T., Nishida, M., Ware, R., A comparison ofgravity wave energy observed by VHF radar and GPS/MET over central North America,J. Geophys. Res., 105, 4685-4687, 2000.Tsuda, T., Nishida, M., Rocken, C., Ware, R. H., A global morphology of gravitywave activity in the stratosphere revealed by the GPS occultation data (GPS/MET), J.Geophys. Res., 105, 7257-7274, 2000.176
STUDIES ON ATMOSPHERIC GRAVITY WAVE ACTIVITY IN THE TROPOSPHEREAND LOWER STRATOSPHERE OVER A TROPICAL STATION AT GADANKID. Narayana Rao 1 , I.V. Subba Reddy 2 , A. Narendra Babu 2 , M. Venkat Ratnam 3 andS. Vijaya Bhaskara Rao 21 National MST Radar Facility, P.B. No.: 123, Tirupati – 517 502, India2 Department of Physics, Sri Venkateswara University, Tirupati - 517 502, India3 Institute for Meteorology, University of Leipzig, Leipzig D-04103, GermanyEmail: isubbareddy@rediffmail.com,profdnrao2001@yahoo.com, drsvbr@redffmail.comAbstractAtmospheric Gravity waves plays a significant role in controlling middle and upperatmospheric dynamics. Till date, frontal systems, convection, wind shear and topography havebeen thought to be the sources of gravity wave activity in the troposphere. All these studies pointedout that, it is very essential to understand generation, propagation and climatology of gravitywaves. In this regard, several campaigns using Indian MST Radar have been carried out to explorethe gravity wave activity in the troposphere and the lower stratosphere. The signatures of thegravity waves in the wind fields have been studied in the troposphere and lower stratosphere. Thewave activity during pre monsoon, monsoon, post-monsoon and winter seasons have been studied.The large wind fluctuations are more prominent above 10 km during pre monsoon and monsoonseasons. The dominant wave periods and their height profiles of amplitudes are studied. Thevertical wavelength and the propagation direction of gravity waves are determined usinghodograph analysis and the same are presented.IntroductionThe recent theoretical studies on gravity waves have shown the importance of excitationand vertical propagation of gravity waves and their forcing on the large scale circulation andstructure of lower and middle atmosphere. In spite of its importance and significant advancements,very few studies are available in the tropical latitudes. VHF Radar is a promising tool to study suchevents and their dynamical effects because of its high temporal and spatial resolution capabilities.There have been few important observations on the generation of gravity waves due to convectionprocess using VHF Radar [Fritts and Nastrom, 1992 ].Most of the sources for the generation of the gravity waves lie in the troposphere [Frittsand Nastrom, 1992]. Some of the sources have been identified as topography [Nastrom andFritts, 1992], convective and frontal activity [Fritts and Nastrom, 1992] and wind shear [Fritts,1984]. Tsuda et al., [1994] also determined that in the equatorial region, gravity wave generationwas typically associated with deep convection. Dhaka et al., [2001], [2002] showed the gravitywaves activities associated with convection over a tropical region by using Indian MST Radar.The generation of gravity waves has also been attributed to various instability mechanismsoccurring in the tropospheric region. Kelvin-Helmholtz instability is one such kind. Theseunstable wind shears are common sources of vertically propagating gravity waves in theatmosphere. Jet streams are identified as a source of gravity wave generation [Fritts and Luo,1992]. These waves have typically wave periods of a few tens of minutes with a horizontalwavelength of a few tens to a few hundreds of kilometers. Near the jet stream maximum windshears are very high providing conditions favoring the occurrences of shear instability andgeneration of gravity waves. Using radiosonde observations Tsuda et al., [1994] showed that177
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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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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
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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: Fig. 8. Zonal wind (top) and temper
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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
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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
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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
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Page 227 and 228: Figure 3: Time-altitude cross-secti
Page 229 and 230: Absorption of cosmic noise is cause
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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
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Silva, Robert R.ATRADAustraliarsilv
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AAdachi, A. .......................
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TTabary, P. .......................
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