Line-of-Sight Winds and Doppler Effect Smearing in ACE-FTS Solar Occultation Measurements

Abstract

Line-of-sight wind profiles are derived from Doppler shifts in infrared solar occultation measurements from the Atmospheric Chemistry Experiment Fourier transform spectrometers (ACE-FTS), the primary instrument on SCISAT, a satellite-based mission for monitoring the Earth’s atmosphere. Comparisons suggest a possible eastward bias from 20 m/s to 30 m/s in ACE-FTS results above 80 km relative to some datasets but no persistent bias relative to other datasets. For instruments operating in a limb geometry, looking through a wide range of altitudes, smearing of the Doppler effect along the line of sight can impact the measured signal, particularly for saturated absorption lines. Implications of Doppler effect smearing are investigated for forward model calculations and volume mixing ratio retrievals. Effects are generally small enough to be safely ignored, except for molecules having a large overhang in their volume mixing ratio profile, such as carbon monoxide.

The Ionospheric Connection Explorer - Prime Mission Review

“…The ICON wind products determined from the green line oxygen emission at 557.7 nm near 100 km have been shown to compare well to the same winds determined from ground-based meteor radars in both day and night (Harding et al 2021). MIGHTI wind measurements also have been used to validate mesospheric wind profiles measured in solar occultation experiments by the ACE-FTS on SCISAT (Boone et al 2021). The temperature and wind products are both now at version 5 and available through August 2023 with efforts now being made to finalize through November and end of mission.…”

“…MIGHTI wind measurements also have been used to validate mesospheric wind profiles measured in solar occultation experiments by the ACE-FTS on SCISAT (Boone et al. 2021 ). The temperature and wind products are both now at version 5 and available through August 2023 with efforts now being made to finalize through November and end of mission.…”