Biases in the thermodynamic structure over the Southern Ocean in ERA5 and their radiative implications

Abstract

The thermodynamic structure of the lower troposphere in the 37 standard levels ERA5 reanalysis has been evaluated against 2,186 high-resolution upper air soundings collected over the Southern Ocean (SO). The reanalysis, which incorporated these soundings, was found to be skilled in depicting the general synoptic meteorology and thermodynamic structure as defined by the cluster analysis of Truong et al. (2020) Journal of Geophysical Research: Atmospheres, 125, e2020JD033214. Using dew-point depression as a proxy for cloud, however, we found a significant reduction in the number of inferred cloud layers, which is inherited from a bias in the specific humidity in the ERA5 reanalysis, most notab..