Quantifying biases in TROPESS AIRS, CrIS, and joint AIRS+OMI tropospheric ozone products using ozonesondes

Abstract. Quantifying changes in global and regional tropospheric ozone is critical for understanding global atmospheric chemistry and its impact on air quality and climate. Satellites now provide multi-decadal records of daily global ozone profiles, but previous studies have found large disagreements in satellite-based ozone trends, including in trends from different products based on the same spectral radiances. In light of these disagreements, it is critical to quantify to what degree the observed trend is attributable to measurement error for each product by comparing satellite-retrieved ozone to long-term measurements from ozonesondes. NASA's TRopospheric Ozone and its Precursors from Earth System Sounding (TROPESS) project provides satellite retrievals of ozone from a suite of instruments, including Cross-track Infrared Sounder (CrIS), Atmospheric Infrared Sounder (AIRS), and multispectral combinations such as AIRS and Ozone Monitoring Instrument (OMI) (joint AIRS+OMI) using a common algorithm. We compare these products to ozonesondes and find that the evolution of global tropospheric ozone satellite–sonde biases for TROPESS CrIS (0.21 ± 3.6 % decade−1, 2016–2021), AIRS (−0.41 ± 0.57 % decade−1, 2002–2022), and joint AIRS+OMI (1.1 ± 1.0 % decade−1, 2004–2022) are less than the magnitude of trends in global tropospheric ozone reported by the Tropospheric Ozone Assessment Report Phase 1 (TOAR-I). We further quantify the bias in regional trends, which tend to be higher but with a smaller number of sondes, which can impact the satellite–sonde bias and trend. Our work represents an important basis for the utility of using satellite data to quantify changes in atmospheric composition in future studies.