Cloud-scale Vertical Velocity Composites of Fair Weather Cumuli at the SGP ARM Climate Research Facility

Arunchandra Chandra McGill University
Pavlos Kollias Stony Brook University
Bruce Albrecht University of Miami

Category: Cloud Properties

Working Group: Cloud Life Cycle

Over land, shallow cumuli coverage is small, yet significantly affects the global radiation budget. This shallow mode of convection over land also plays an important role in the preconditioning of deep convection through the regulation of the heat and moisture transport in the lower troposphere. Records of vertical velocity measurements in fair weather cumuli from aircraft penetrations and ground-based cloud radars have exhibited great variability in 1D and 2D with often an updraft core and downdrafts near cloud edges reported. Our aim here is to develop composites (observational models) of the dominant (most frequently observed) vertical velocity structures in fair-weather cumulus (e.g., investigate if downdrafts are prominent near the cloud edges, if penetrative downdrafts are present, or if updraft structure extends from the cloud base to the cloud top). This study uses high temporal and spatial resolution cloud radar (35/94 GHz) measurements at the Southern Great Plains (SGP) ARM Climate Research Facility during summer months. This study differs from previous studies that look at macroscopic properties of fair-weather cumuli by documenting several vertical velocity statistics per cloud entity using normalized cloud depth and width. This detail documentation could lead to the development of a scheme for the classification of shallow clouds to active/passive and to investigate the impact of entrainment of cloud structure.

This poster will be displayed at ASR Science Team Meeting.