Abstract
Abstract. An updated empirical climatic zonally averaged prevailing wind model for the upper mesosphere/lower thermosphere (70-110 km), extending from 80°N to 80°S is presented. The model is constructed from the fitting of monthly mean winds from meteor radar and MF radar measurements at more than 40 stations, well distributed over the globe. The height-latitude contour plots of monthly mean zonal and meridional winds for all months of the year, and of annual mean wind, amplitudes and phases of annual and semiannual harmonics of wind variations are analyzed to reveal the main features of the seasonal variation of the global wind structures in the Northern and Southern Hemispheres. Some results of comparison between the ground-based wind models and the space-based models are presented. It is shown that, with the exception of annual mean systematic bias between the zonal winds provided by the ground-based and space-based models, a good agreement between the models is observed. The possible origin of this bias is discussed.Key words: Meteorology and Atmospheric dynamics (general circulation; middle atmosphere dynamics; thermospheric dynamics)
Highlights
Numerous attempts have been undertaken to construct a 2 D empirical wind model of the upper atmosphere that includes the upper mesosphere/lower thermosphere region
A description of the global zonal wind structure at 70±110 km is given in the Fleming et al (1988) model
In that model the zonal wind below 85 km was calculated from the thermal wind equation and the related temperature was determined from satellite radiance measurements
Summary
Numerous attempts have been undertaken to construct a 2 D empirical wind model of the upper atmosphere that includes the upper mesosphere/lower thermosphere region. A well-known meridional wind model for this region (Groves, 1969) has been developed utilizing rather sporadic rocket wind data, which were obtained at only a few sites in the Northern Hemisphere (NH) As a result, this model presented a quite schematic picture of the height-latitudinal structure of a zonal mean meridional wind ®eld at 60±110 km for separate seasons. Solovjova: Global empirical wind model for the upper mesosphere/lower thermosphere This conclusion of meridional wind ageostrophicity for dierent seasons was made by Portnyagin (1986) who analyzed ground-based meridional wind observations for sites located in two narrow latitudinal belts and situated far apart in longitude. A model known as`interim new CIRA'' contained a set of radar derived direct wind measurements for 14 locations (Manson et al, 1985) These were extensively discussed (Manson et al, 1985), and much useful information about global wind structures in the upper mesosphere/lower thermosphere region was obtained.
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