On the Synergy Between Space-Borne Remote Sensing and Large-Eddy Simulation: Structure of Shallow Marine Convection

Abstract:

The representation of marine shallow clouds in global models is recognized as a significant source of uncertainty in climate projections according to the Intergovernmental Panel on Climate Change (IPCC). The synergy between space-borne observations and high-resolution simulation is investigated through a series of large-eddy simulations (LES) that are based on A-Train observations of marine cloudy boundary layers. The main aims of the study are to advance the understanding of the atmospheric boundary layer physics and increase the utility of both observations and modeling. Using a combination of multi-sensor A-train data and model reanalysis, high resolution, cloud regime-type large-eddy simulations of selected scenes are carried out. For instance, temperature, humidity profiles and sea surface temperature from the Atmospheric Infrared Sounder (AIRS), and geostrophic wind from reanalysis are used in the LES. Although the AIRS soundings lack fine structure in the boundary layer and often exhibit small deviations from the actual atmospheric state, the simulations show that a more precise profile can be obtained. The quantitative characteristics of the cloud structure are used to compare the LES results with reflectances from the Moderate Resolution Imaging Spectroradiometer (MODIS). Implications related to the dynamics of the boundary layer and its modeling in global models are also discussed.