Thermospheric wind retrievals from the SOFPIT Fabry–Perot interferometer at 630 nm

Thermospheric winds play a crucial role in transporting momentum and energy in the upper atmosphere, influencing both its composition and dynamics, with direct implications for satellite operations and global communication systems. The Fabry–Perot interferometer (FPI) is a key remote-sensing instrument for measuring thermospheric winds by observing Doppler shifts and Doppler broadening of naturally occurring airglow emissions. In March 2024, DLR installed a 630 nm FPI (SOFPIT) on Tenerife (28.29° N, 16.63° W; 32.79° N, 60.75° E geomagnetic), enabling high-resolution observations of upper-atmosphere winds.

We implemented two retrieval methods tailored to the SOFPIT instrument. The first method, based on Shiokawa et al. (2012), compares images taken in opposite directions (east–west, north–south), assuming wind uniformity across the field of view. The second method, following Makela et al. (2011), uses a forward model simulating the instrument response for given wind and temperature values; observed images are then fitted to the model to infer winds, requiring a zero-wind reference for absolute calibration.

Both approaches have been successfully applied to the entire SOFPIT dataset since the start of observations, demonstrating the robustness and reliability of the retrieval techniques. These results confirm that the instrument can consistently measure thermospheric winds and provide a solid foundation for ongoing improvements in data processing and calibration.

Our study highlights the effectiveness of FPIs for detailed monitoring of upper-atmosphere dynamics. Such measurements are essential for improving our understanding of thermospheric behavior and supporting operational forecasting in space weather and satellite mission planning.