Intersection of a Sloping Aerosol Layer Observed by Airborne Lidar with a Cloud-Capped Marine Boundary Layer

Abstract

The NCAR Airborne Infrared Lidar System (NAILS) observed the edge of an extended, sloping aerosol layer that intersected a stratocumulus cloud deck over the Pacific Ocean during the First ISCCP (International Satellite Cloud Climatology Project) Regional Experiment, 260 km WNW of San Diego. In situ measurements support the interpretation of the lidar observations as arising from a particle-laden layer with relatively clean air above, below, and to the SW. Intersection of these sloping layers with cloud top leads to substantial horizontal variability of boundary-layer structure in the intersection region. The intersection of the aerosol layer with cloud top also corresponded closely to a quasi-linear trough in the cloud top that showed enhanced brightness and an enhanced number of small particles.