Proceedings with Extended Abstracts (single PDF file) - Radio ...

RADAR, OPTICAL AND SATELLITE STUDIES OFCLIMATOLOGY AND EFFECTS OF ATMOSPHERIC GRAVITYWAVES AND TURBULENCENikolai M. GavrilovAtmospheric Physics Department, Saint-Petersburg State University, Petrodvorets, St.Petersburg, 198504, Russia, gavrilov@pobox.spbu.ruAbstract. Some results of studies of climatology of internal gravity waves (IGWs) in themiddle and upper atmosphere are presented. MST and MF radars give information aboutseasonal and interannual changes of the mean winds and IGW variances. Low-orbitsatellites receiving GPS signals may give distribution of zones of increased IGW andturbulence intensity and of wave generation. Multi-beam MST radar observations giveinformation about mesoscale nonlinear IGW sources in the tropo-stratosphere. Numericalmodels allow to study sensitivity of general circulation of the middle atmosphere toglobal inhomogeneity of IGW sources observed with radars and GPS satellites.1. IntroductionFor better understanding and interpreting, MST radars studies should be completed byother observations with various ground-based and satellite techniques and by theoreticalstudies. In this paper, we present a short review of some recent studies of climatology ofinternal gravity waves (IGWs) in Saint-Petersburg University (Russia). These studiesinclude an analysis of seasonal and interannual variations of wind velocity in the middleatmosphere with MST and medium frequency (MF) radars, optical observations of shortperiodvariations of night airglows, analysis of global structure of IGWs and their sourcesin the lower and middle atmosphere from the data of low-orbit GPS satellites. Numericalmodeling of IGW spectrum propagation in the atmosphere and study of sensitivity of anumerical model of general circulation of the middle atmosphere to observed horizontalinhomogeneity of IGW distribution at low boundary are discussed.2. Analysis of radar data.In the last years, a considerable progress has been achieved in studies of IGWclimatology with radar technique in the atmosphere. A group of Saint-PetersburgUniversity participated in joint analyses of the data from Saskatoon medium frequency(MF) radar [Gavrilov et al., 1995], from Japanese MU radar [Gavrilov et al., 2000], frommulti-year D1 observations of ionospheric drifts at Collm Observatory, Germany[Gavrilov et al., 2001], and from other meteor and MF radars. Recently, an analysis ofseasonal and interannual variations of IGW characteristics at altitudes of 70 – 90 km overHawaii (22° N, 159° W) from the data of MF radar was made [Gavrilov et al., 2003a,b].Hawaii MF radar gives the wind velocity values with time step of about 2 min andheight resolution of 2 km. For each altitude, we obtain hourly mean values of zonal andmeridional wind velocity components and their hourly variances. The latter giveinformation about wind perturbations with time scales up to 1 hr, which are called as"within hour" (WH) data. Differences of consecutive hourly data give information aboutperturbations with periods 1 – 5 hr (HD data). Transmission functions of these numericalfilters are described by Gavrilov et al. [2003a]. After calculating hourly-mean velocitiesand WH and HD perturbations, we calculate monthly mean values taking account ofnumbers, n i , of good velocity measurements during each hour. Obtained monthly meanwinds and variances we use in this paper for the study of seasonal changes of the mean168