Characterization of the wintertime marine boundary-layer cloud properties occurring over the eastern North Pacific Ocean based upon recent shipboard observations collected during MAGIC

Description

This shipboard deployment of the second ARM Mobile Facility (AMF) for the Marine ARM GPCI Investigation of Clouds (MAGIC) field campaign has recently collected wintertime cloud property observations along a transect which runs from the cool waters off the California coast to the warm tropical waters of Hawaii. This transect is significant in that it runs near the GPCI intercomparison transect frequently used by cloud modelers to evaluate simulations of the transition in cloud type from stratocumulus, to cumulus, to deep convective.

The spatially varying sea surface temperatures (SST) observations collected along this transect are reflected in the deepening of the marine boundary layer (MBL) and concomitant transitions in cloud type as the ship moves towards the west. We examine the boundary-layer depth through a detailed evaluation of the atmospheric convective indicators, convective available potential energy (CAPE) and convective inhibition (CIN). In addition, the effects of a spatially varying MBL on both the macrophysical cloud properties (cloud thickness and liquid water) and the observed microphysical properties (droplet size and concentration) are examined.