EMPIRICAL WIND MODEL FOR THE UPPER, MIDDLE AND LOWER ATMOSPHERE

The HWM90 thermospheric wind model has been revised in the lower therm osphere and extended into the mesosphere, stratosphere and lower atmos phere to provide a single analytic model for calculating zonal and mer idional wind profiles representative of the climatological average for various geophysical conditions. Gradient winds from CIRA-86 plus rock et soundings, incoherent scatter radar, MF radar, and meteor radar pro vide the data base and are supplemented by previous data driven model summaries. Low-order spherical harmonics and Fourier series are used t o describe the major variations throughout the atmosphere including la titude, annual, semiannual, local time (tides), and longitude (station ary wave 1), with a cubic spline interpolation in altitude. The model represents a smoothed compromise between the original data sources. Al though agreement between various data sources is generally good, some systematic differences are noted, particularly near the mesopause. Ove rall root mean square differences between data and model values are on the order of 15 m/s in the mesosphere and 10 m/s in the stratosphere for zonal winds, and 10 m/s and 5 m/s respectively for meridional wind s. (C) 1996 Published by Elsevier Science Ltd.