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

Abstract. Quantifying changes in global and regional tropospheric ozone are critical for  understanding global atmospheric chemistry and it's 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 CrIS, AIRS, and multispectral combinations such as AIRS and OMI (joint AIRS+OMI) using a common algorithm. We compare the long-term changes in these products to ozonesondes and find that the evolution of global tropospheric ozone satellite-sonde bias 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) is approximately one third 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.