Ground-Based Optical Measurements of Quiet Time Thermospheric Wind and Temperature: Atmospheric Scattering Corrections

摘要

Ground-based measurements of thermospheric wind and temperature are known to be affected by tropospheric scattering during geomagnetically active times, when horizontal airglow gradients are large. In this work, we present an analysis of the effects during quiet times, when horizontal airglow gradients can be assumed to be negligible, and we derive corrections to be applied to historical and future data sets. These corrections are easy to apply, depending only upon the optical thickness of the atmosphere and the measured wind, not the viewing direction or temperature. If these corrections are not applied, all winds estimated from ground-based observatories are underestimated by about 10% (depending on the optical thickness), and temperatures are overestimated by a couple K. We present observational evidence of the effect of atmospheric scattering on temperature measurements using 5 years of data from the North American Thermosphere Ionosphere Observing Network. We find that the temperatures measured to the east and west are statistically larger than the temperatures measured to the zenith. This is consistent with our analysis of the effect of atmospheric scattering, though the difference in the measurements is slightly larger than the theoretical prediction.