A fast spectral line-ratio algorithm for mesospheric airglow rotational temperature retrieval and validation
Year: 2026
Type: article
Abstract: Airglow rotational temperatures are effective tracers of variability in the mesopause region. To improve computational efficiency in processing long-duration, high-temporal-resolution observations from the Mesospheric Airglow Spectrum Photometer (MASP), a Fast Airglow Spectral Line-Ratio algorithm (FASLR) is developed for rotational temperature retrieval. FASLR uses forward-modeled synthetic spectra to establish ratio–temperature relationships, derives independent temperature estimates from multiple line-intensity ratios, and combines them with weights based on the relative sensitivity of each ratio to instrumental perturbations. For the two test nights containing 132 and 120 observations, the complete FASLR processing required 19.0 and 16.8 s, respectively. FASLR temperatures are compared with two nights of co-located sodium fluorescence Doppler lidar observations. The major nocturnal temperature variations are generally similar between the two measurements, while differences in their absolute temperature levels are also observed. The algorithm is then applied to six nights of dual-channel MASP observations of the O 2 (0–1) and OH (6–2) emissions and compared with independent satellite observations from SABER and Aura/MLS, as well as temperature estimates from SD-WACCMX and NRLMSIS 2.1. At representative emission-layer altitudes, the O 2 rotational temperatures are generally closer to NRLMSIS 2.1 in overall temperature level, although their nocturnal variations differ. The OH temperatures are higher than NRLMSIS 2.1 early in the night but become closer later. SD-WACCMX generally gives lower temperatures and weaker nocturnal variability in both emission layers. Case studies further show longer-period nocturnal variability and shorter-period disturbances in the FASLR-derived temperatures. On 2 February 2024, temperature and intensity perturbations in the O 2 and OH layers exhibit a common dominant period band and stable phase relationships. On 7 February 2024, both layers show concurrent power enhancements within a similar period band, and simultaneous observations from the Mesospheric Airglow Wide-angle Imager (MAWI) independently support the identified disturbance. Overall, FASLR provides an efficient approach for dual-channel airglow temperature retrieval and supports investigations of wave-related variability in the mesopause region.
Language: English
Subfield: Space and Planetary Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,585
OpenAlex ID: W7168163951