Evaluation of Tropospheric Moisture Characteristics Among COSMIC-2, ERA5 and MERRA-2 in the Tropics and Subtropics

Global navigation satellite system (GNSS) radio occultation (RO) receivers onboard the recently-launched COSMIC-2 (C2) constellation provide an unprecedented number of high vertical resolution moisture profiles throughout tropical and subtropical atmosphere. In this study, distribution variability water vapor was investigated using specific humidity retrievals from C2 observations compared to collocated ERA5 MERRA-2 reanalysis within 40°N 40°S September December 2019, which is prior assimilation in reanalyses. Negative biases are evident boundary layer, so we focused on levels above layer study. Overall, shows excellent agreement with that has larger differences MERRA-2. mid-troposphere, positive (6–12%) negative (15–30%). Strong correlations observed between subtropics (>0.8) whereas slightly weaker deep tropics, especially for Profile pairs large often occur areas sharp gradients, highlighting importance measurement resolution. Locations demonstrated active convection regions show a bias at 3 km higher environments, displays 7 km. However, additional explanations profile remain unclear require further