The Comparison Between Remote Sensor Measurements and Reanalysis of Cloud Morphology and Thermodynamics over the Eastern North Atlantic

The Eastern North Atlantic (ENA) is frequently associated with extensive coverage of stratocumulus clouds. The transition process from unbroken single-layer stratocumulus clouds to broken cumulus clouds is primarily determined by the surface fluxes and vertical turbulent transports in the marine boundary layer (MBL). We classified clouds over the ENA according to the stages in the transition process: single-layer stratocumulus evolving into cumulus-coupled stratocumulus, then to scattered, broken cloud cells due to the weakening of inversion. We investigated the thermodynamic profiles, cloud coverage, and surface fluxes for each cloud classification using data collected from the Ka-band Zenith Radar and Doppler Lidar during the Atmospheric Radiation Measurement (ARM) Aerosol and Cloud Experiments in the ENA (ACE-ENA) campaign, which was then compared with ERA-5 reanalysis data from the European Center for Medium-Range Weather Forecasts (ECMWF). As a result, drizzle evaporation rates and the associated latent heat fluxes are found to be substantial only in cumulus-coupled MBL. On average, the comparison of thermodynamic profiles and cloud fraction between remote sensor measurements and reanalysis showed that single-layer stratocumulus and broken clouds are well-represented by ERA-5, whereas drizzling and cumulus-topped stratocumulus clouds are underrepresented.