The Tropospheric Emissions: Monitoring of Pollution (TEMPO) Level 0-1 Processor – Algorithm Updates and Performance Assessment

We present the status of the Level 0-1 processor for the Tropospheric Emissions: Monitoring of Pollution (TEMPO). Through multiple version updates, the TEMPO Level 1 product has undergone significant enhancements to improve the radiometric and spectral calibration performance. The Level 0-1 algorithm enhancements, such as updates in electronic offset, smear, dark current, diffuser goniometry, and stray light corrections, have led to quality improvements in Level 2 products. The high-performance Level 0-1 processor also enabled the detection of city lights, nightglow, and aurora signals from TEMPO during twilight scans. However, assessments of TEMPO Level 1 data (versions 1 to 3) indicated overestimations of Sun-normalized radiances compared to radiative transfer calculations. Notably, limited analyses indicated that the positive percentage biases showed no significant wavelength dependence within the spectral range of 320–400 nm, suggesting imperfect characterization or correction of parameter(s) with a spectrally flat influence. Indirect assessments using Level 2 cloud retrievals also implied overestimations in TEMPO Sun-normalized radiances at 466 nm. In this work, we present assessments of possible contributors to the overestimations and suggest potential mitigation approaches.