First two years of TEMPO nitrogen dioxide and formaldehyde observations:algorithm status and highlights

Tropospheric Emissions: Monitoring of Pollution (TEMPO) is observing air quality andatmospheric composition over North America from a geostationary orbit since its operationsstarted in August 2023. TEMPO observes the continent every 40 to 60 minutes at a spatialresolution on the order of ~ 2 x 4.5 km 2 . Together with the Geostationary EnvironmentMonitoring Spectrometer (GEMS, launch 2020) monitoring Asia and the Sentinel-4/UVN(launch 2025) monitoring Europe, TEMPO is part of the current global constellation ofgeostationary sensors devoted to the observation of air quality. Like GEMS and Sentinel-4/UVN,TEMPO uses backscattered ultraviolet and visible solar radiation to retrieve atmosphericamounts of key trace gases and aerosols associated with air quality and atmospheric chemistry.Among the species retrieved from TEMPO observations of nitrogen dioxide and formaldehydeare important to understand emissions and atmospheric chemistry, including the formation anddestruction of tropospheric ozone.After multiple version updates over the first two years of the mission, the TEMPO Level 2 NO 2and HCHO products have undergone significant enhancements to improve the performance andaccuracy of the slant column retrievals, air mass factor calculations and post-processingcorrections including destriping for NO 2 and background for HCHO. We illustrate theperformance of both retrievals (version 3 & 4), evaluating their fitting uncertainty and showingcomparisons with independent correlative measurements and other satellite products showcasingsmall noise levels and remarkable accuracy with well quantified biases. We continue byillustrating the capacity of TEMPO products focusing on different case studies showingTEMPO’s high temporal and spatial resolution. We finalize discussing aspects of the retrievalsubject to improvement and our plans to address them.