Vertical Air Motion Retrievals in Deep Convective Clouds using the
ARM Scanning Radar Network in Oklahoma during MC3E
Kirk W. North1, Pavlos Kollias1,2, Scott E. Giangrande3, Scott M. Collis4, and Corey K. Potvin51Department of Atmospheric and Oceanic Sciences, McGill University, Montreal, Quebec, Canada 2School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, New York, USA 3Atmospheric Sciences Division, Brookhaven National Laboratory, Upton, New York, USA 4Environmental Science Division, Argonne National Laboratory, Lemont, Illinois, USA 5Cooperative Institute for Mesoscale Meteorological Studies, and NOAA/OAR/National Severe Storms Laboratory, and School of Meteorology, University of Oklahoma, Norman, Oklahoma, USA
Received: 22 Aug 2016 – Accepted for review: 22 Aug 2016 – Discussion started: 01 Sep 2016
Abstract. The U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) program's Southern Great Plains (SGP) site includes a heterogeneous distributed scanning Doppler radar network suitable for collecting coordinated Doppler velocity measurements in deep convective clouds. The surrounding National Weather Service (NWS) Next Generation Weather Surveillance Radar 1988 Doppler (NEXRAD WSR-88D) further supplements this network. Radar velocity measurements are assimilated in a three-dimensional variational (3DVAR) algorithm that retrieves horizontal and vertical air motions over a large analysis domain (100 km x 100 km) at storm-scale resolutions (250 m). For the first time, direct evaluation of retrieved vertical velocities with those from collocated 915-MHz radar wind profilers is performed. Mean absolute and root-mean-square differences between the two methods are on the order of 1 m s−1 and 2 m s−1, respectively. Moderate time-height correlations on the order of 0.5 are also shown to exist between the two methods. An empirical sensitivity analysis is done to determine a range of 3DVAR constraint weights that adequately satisfy both velocity observations and anelastic mass continuity. It is shown that the vertical velocity spread over this range is on the order of 1 m s−1. A similar sensitivity analysis reveals that iterative multi-Doppler techniques have difficulty satisfying velocity observations and mass continuity simultaneously. These results provide a form of assurance in the use of 3DVAR retrieved vertical velocities for evaluating numerical simulations of deep convective clouds.
North, K. W., Kollias, P., Giangrande, S. E., Collis, S. M., and Potvin, C. K.: Vertical Air Motion Retrievals in Deep Convective Clouds using the
ARM Scanning Radar Network in Oklahoma during MC3E, Atmos. Meas. Tech. Discuss., doi:10.5194/amt-2016-269, in review, 2016.