Spatial mapping of the thermospheric neutral wind field

There are many possible observing strategies available for mapping the thermospheric wind field by using observations of the Doppler shift of the O (¹D) airglow with a Fabry-Perot interferometer. The determination of the neutral wind field from observed line-of-sight velocities invariably involves some assumptions about the nature of the wind field. A standard method of observing employs the assumption that horizontal gradients in the wind field are linear. An analysis of measurements from Arecibo, Puerto Rico, that makes use of this assumption, is discussed. For work at high latitudes this assumption may be unrealistic. An alternative approach that requires that local time and longitude be interchangeable, but eschews the assumption of linear gradients has been developed and used at Ann Arbor, Michigan, and Calgary, Alberta. We examine these different techniques, and illustrate the discussion with some typical results.