Factors Driving the Deepening of the Subtropical Marine Stratocumulus Planetary Boundary Layer

A twice-daily product quantifying the height of the subtropical marine stratocumulus planetary boundary layer (PBL) has been created using multiple A-train satellites (CALIPSO, MODIS) for cloud amounts greater than 30%. This product offers four years of continuous twice-daily observations and is studied in conjunction with a set of ~170,000 48-hour boundary layer trajectories in four subtropical eastern ocean basins, all starting along the A-Train track.

Biases caused by geographical and seasonal irregularities and sensor veiwing angles are taken into account. We present a statistical approach for comparing mean changes between trajectories grouped by differing initial conditions, taking into account variable cross-correlation. Preliminary results suggest that boundary layer deepening is driven by many variables independently of one-another including decreased upper level humidity, increasing sea surface temperature, decreasing subsidence, and increased droplet concentration, while precipitation observed by CloudSat appears to inhibit PBL deepening.