An evaluation of cloud vertical structure in three reanalyses against CloudSat/cloud‐aerosol lidar and infrared pathfinder satellite observations

Abstract Cloud fraction is a great source of uncertainty in current models. By utilizing cloudiness fields from CloudSat/cloud‐aerosol lidar and infrared pathfinder satellite observations (CALIPSO), the three widely used reanalyses including the Interim ECWMF Re‐Analysis (ERA‐Interim), Japanese 55‐yar Reanalysis (JRA‐55), and the Modern‐Era Retrospective Analysis for Research and Applications (MERRA‐2) are assessed for their representation of cloudiness. Results show all three reanalyses can basically capture the cloud horizontal pattern and vertical structure as in CloudSat/CALIPSO, yet the magnitude is markedly underestimated, in particular for JRA‐55 and MERRA‐2. Besides, all reanalyses struggle to simulate the mid‐level clouds at low latitudes. In addition to these common deficiencies, the three reanalyses have their own distinctive behaviors and differ from one another. While ERA‐Interim and JRA‐55 show better performance for low‐level clouds in the tropics, they exhibit remarkable underestimation for high‐level clouds. On the contrary, MERRA‐2 succeeds in representing high‐level clouds but dramatically underestimates the low and mid‐level clouds at low latitudes. As a measure of subgrid‐scale variability of moisture, the derived “critical relative humidity (RH c)” from CloudSat/CALIPSO exhibits distinctive vertical structures at different latitudes, it is thus speculated that poor specification or parameterization of RH c is responsible for these bias behaviors