The GOME-type Tropical Tropospheric Ozone Essential Climate Variable (GTTO-ECV) satellite data record between 1995 and 2023

A tropospheric ozone Climate Data Record from 1995 until end 2023 has been generated within ESA’s Climate Change Initiative programme. The GOME-type Tropical Tropospheric Ozone Essential Climate Variable (GTTO-ECV) satellite data record combines data from GOME, SCIAMACHY, OMI, the three GOME-2 missions and TROPOMI. The retrieval is based on the Convective Cloud Differential technique, which limits the coverage to the tropical belt (20°S to 20°N). We generated two monthly mean data sets at 1° x 1° resolution: one corresponds to a tropospheric column up to 200 hPa as in the previous CCI data release (Heue et al., 2016), while the other is limited to 270 hPa this pressure level is used in the operational S5P data set. Besides a consistent reprocessing of the CCD data for individual sensors, we also updated the harmonising scheme. The mean bias as well as the mean annual cycle relative to the reference instrument (OMI) are used to correct for the differences between the sensors. Heue et al (2016) inferred a mean tropospheric ozone trend of +0.7±0.1 DU/decade (1995-2015) from the previous GTTO-ECV version. Did the trend change with the extended and improved data set? The GTTO-ECV data record will be used to investigate the tropical mean trend as well as temporal and local changes in the trends or extreme events.