Atmospheric scattering effects on ground-based measurements of thermospheric vertical wind, horizontal wind, and temperature

Ground-based Fabry-Perot interferometers routinely observe large vertical winds in the thermosphere, sometimes reaching over 100 m/s. These observations, which use the Doppler shift of the 630.0 nm airglow emission to estimate the wind, have long been at odds with theory. We present a summary of 5 years of data from the North American Thermosphere-Ionosphere Observing Network, showing that large apparent vertical winds are a persistent feature at midlatitudes during geomagnetic storms. We develop a radiative transfer model which demonstrates that these measurements can be explained as an artifact of the scattering of light in the troposphere. In addition to the example from midlatitudes, we apply the model to low latitudes, where we show that the postsunset vertical winds routinely measured over Brazil are explained in part by atmospheric scattering. Measurements of the horizontal wind and temperature are also affected, with errors reaching 400 m/s and 200 K in the most extreme cases.