06/28/2013
New Method of Operating Wind Profilers Yields Properties of Convective Storms
Summary
Substantial uncertainty in global climate model (GCM) predictions of possible climate change can be attributed to the manner in which the effects of deep cumulus convection (thunderstorms) are represented. To elucidate the complex interactions between storm dynamics, thermodynamics, and microphysics of deep convection, better understanding of vertical air motion in convective systems is needed. Direct measurements of this quantity are rare due to the hazards of flying aircraft into thunderstorms. Therefore, remote-sensing solutions are needed to develop long-term characterization of this parameter under different environmental conditions. Researchers have now developed a novel configuration for commercial wind profilers deployed at the Atmospheric Radiation Measurement (ARM) Climate Research Facility that enabled them to measure updrafts and downdrafts of convective storms passing over the site. Initial results from two observation campaigns revealed that intense updraft cores with magnitudes exceeding 15 m/s were routinely observed, while downdraft cores were less frequently observed and had weaker magnitudes. They also examined the relationship between maximum updraft intensity and updraft diameter, a key relationship used in many model convective parameterizations. They found weaker correlations between the two quantities than usually assumed in models. The team plans to develop routine operational processing for the new measurement configuration to produce long-term statistics of convective properties. This unique dataset will provide statistics on convective properties across a wide range of environmental conditions, enabling climate modelers to develop improved convective formulations that work under a wider variety of conditions and reducing uncertainty in GCM simulations of the hydrological cycle.
References
Giangrande, S. E., S. Collis, J. Straka, A. Protat, C. Williams, and S. Krueger. 2013. “A Summary of Convective Core Vertical Velocity Properties Using ARM UHF Wind Profilers in Oklahoma,” Journal of Applied Meteorology and Climatology , ACCEPTED. DOI: 10.1175/JAMC-D-12-0185.1.