An update to the Horizontal Wind Model (HWM): The quiet time thermosphere

The Horizontal Wind Model (HWM) has been updated in the thermosphere with new observations and formulation changes. These new data are ground‐based 630 nm Fabry‐Perot Interferometer (FPI) measurements in the equatorial and polar regions, as well as cross‐track winds from the Gravity Field and Steady State Ocean Circulation Explorer (GOCE) satellite. The GOCE wind observations provide valuable wind data in the twilight regions. The ground‐based FPI measurements fill latitudinal data gaps in the prior observational database. Construction of this reference model also provides the opportunity to compare these new measurements. The resulting update (HWM14) provides an improved time‐dependent, observationally based,…