Characterization of the Northeast Pacific Stratocumulus-to-Cumulus Transition Using Airborne Passive Remote Sensing Measurements

The transition from stratocumulus to cumulus clouds in the world’s eastern subtropical basins has a large impact on the planetary albedo, and is intimately linked to the cloud-top longwave cooling. In this presentation we make use of airborne measurements taken by the NSF Gulfstream V during the Cloud System Evolution over the Trades (CSET) campaign held over the northeast Pacific in the summer of 2015. This study relies primarily on the passive remote sensing measurements that can link the cloud properties to their radiative impact as part of the transition. These measurements include solar spectral irradiances, from which cloud optical depths and cloud effective radii can be retrieved, millimeter-wavelength brightness temperature-retrieved cloud liquid water path and water vapor paths, and broadband infrared and solar measurements. One emphasis is on understanding the connection between the optically-thin detrained cloud layers, to their parent cloud, and understanding the radiative role of the optically-thin cloud layers within the transition.