Characterize Marine Atmospheric Boundary Layer (MABL) Structure with CALIPSO Lidar Measurements

The marine atmospheric boundary layer (MABL) structure is important to the marine low cloud processes, and the exchange of heat, momentum, and moisture between oceans and the low atmosphere. An algorithm was developed to identify the MABL top (boundary layer height, BLH) and the mixing layer height (MLH) by using the MABL aerosol lidar backscattering from the CALIPSO lidar Observations. The evaluation results with island- and ship-based lidar and radiosonde measurements indicated that the algorithm performs well. The algorithm was applied to 4-year CALIPSO measurements over the eastern Pacific region to characterize the MABL de-coupling structure. The MABL data were synergized with other A-train satellite measurements to further explore the controlling factors of MABL structure over the global oceans. Results showed that the MABL is generally decoupled with MLH/ BLH ratio ranging from ~0.5 to ~0.8 over the eastern Pacific Ocean region. The MBL decoupling magnitude is mainly controlled by estimated inversion strength (EIS), which in turn controls the cloud top entrainment process. The systematic differences between drizzling and non-drizzling stratocumulus tops also show dependence on EIS. This may be related to the mesoscale circulations or gravity wave in the MABL. Further analysis indicates that the MABL shows a similar decoupled structure for clear-sky and cumulus-cloud-topped conditions but is better mixed under stratiform cloud breakup and overcast conditions.