Lagrangian Case Studies of Marine Boundary Layer Evolution from Combined Satellite-Aircraft Observations

The Cloud System Evolution in the Trades (CSET) field campaign took place July/August 2015 to study the evolution of clouds, precipitation, and aerosols in the stratocumulus-to-cumulus (Sc-Cu) transition region of the northeast Pacific marine boundary layer (MBL). The sampling strategy, where MBL airmasses were sampled with the NSF/NCAR Gulfstream-V (HIAPER) and resampled then at their advected location two days later, resulted in a dataset of 14 paired flights suitable for Lagrangian analysis. From these flight pairs and corresponding satellite and reanalysis data along boundary layer trajectories, we can construct a rich Lagrangian dataset. Although nearly all sampled airmasses experienced a transition in cloudiness, the relationship between conventional controls on MBL evolution and subsequent chances in cloud features is complex. Two case studies are presented, with differing aerosol and meteorological forcings. We explore the resulting differences in boundary layer evolution, focusing on depth, decoupling, and cloudiness.