Tropical water vapor and large-scale circulation from CMIP6 GCMs and ESA CCI+ "Water Vapor" climate data records

International audienceThe atmospheric water cycle is strongly associated with global climate variations, especially in the tropical region (30°S-30°N). However, the representation of the relation from models and observation results remains unknown. Here the water vapor observed during 2003~2014 over the tropical region is analysed concerning large-scale circulation for 7 global climate models (CMIP6 framework), ERA5 reanalysis data, and the new global water vapor climate data records (CDR) generated within the ESA Water Vapor CCI+ project (ESA TCWV-COMBI). As the ESA TCWV-COMBI observes water vapor over the land area under clear-sky conditions and all-weather conditions without heavy precipitation in the ocean areas, the evaluation is conducted with land-sea separation. The observational diagnostic relies on the decomposition of the tropical atmosphere into large-scale dynamical regimes using the 500 hPa atmospheric vertical velocity w500 (in hPa/day) as a proxy. The datasets are sorted according to dynamical regimes (intervals of 10 hPa/day) to analyze the evolution of the regimes in terms of frequency of occurrence and is linked to water vapor variation. Although the inter-model spread lies within the interannual spread of the ESA CCI+_WV data, there are noticeable differences between the models and observations that are linked to large-scale dynamics