The Tropospheric Emissions: Monitoring of Pollution (TEMPO) Level 0-1 Processor – Radiometric calibration and intercomparison

We present the status of the Level 0-1 processor for the Tropospheric Emissions: Monitoring of Pollution (TEMPO), with a primary focus on radiometric calibration. Multiple version updates have significantly improved the TEMPO Level 1 products, enhancing the quality of Level 2 products and enabling the detection of city lights, nightglow, and aurora signals during twilight hours. However, assessments of TEMPO Level 1 data (versions 1 to 3) indicated overestimations of Sun-normalized radiances when compared to radiative transfer calculations. To investigate these biases, we compared TEMPO solar irradiance measurements to those from multiple independent instruments and a high-resolution reference solar spectrum. For Earth radiance assessments, we conducted intercomparisons with spaceborne measurements from the Advanced Baseline Imager (ABI) instruments onboard the Geostationary Operational Environmental Satellite (GOES)-16 and -19. Located at the checkout position of 89.5°W for post-launch testing, GOES-19 ABI has provided comparable viewing geometries with TEMPO (at 91.0°W) over North America. On the other hand, comparisons with GOES-16 ABI (located at 75.2°W) may require corrections for viewing angles and bidirectional reflectance distribution function (BRDF) effects due to larger differences in geometries. Additionally, we compared TEMPO Sun-normalized radiances with radiative transfer simulations over Railroad Valley, which use ground-based surface reflectance measurements as input. In this work, we present the intercomparison results and propose potential approaches to mitigate the radiometric biases.