Horizontal Wind Model (HWM)

The HWM is an empirical model of the horizontal neutral wind in the upper thermosphere. With the increasing complexity of coupled whole atmosphere models it is important to have an accurate observationally derived climatological specification of the atmosphere’s wind fields. HWM is able to provide a reasonable representation the variations of middle- and upper-atmosphere winds because they are predominantly driven by in situ solar heating under the periodic cyclical influence of the earth’s rotation, tilt, and orbit around the sun. When and where appropriate, HWM reduces the computational complexity of theoretical and applied calculations by avoiding the need to simultaneously compute the wind fields from first principles. The model software provides zonal and meridional winds for specified latitude, longitude, time, and Ap index.