HR: 1330h
AN: H23A-03    [Abstracts]
TI: Space-Time Variability of Reflectivity Estimated by Vertically Pointing and Scanning Radars during TEFLUN-B
AU: * Williams, C R
EM: Christopher.R.Williams@noaa.gov
AF: University of Colorado at Boulder, Cooperative Institute for Research in Environmental Sciences (CIRES) and NOAA Aeronomy Laboratory, Mail Stop R/AL3 325 Broadway, Boulder, CO 80305 United States
AU: Gage, K S
EM: Kenneth.S.Gage@noaa.gov
AF: NOAA Aeronomy Laboratory, Mail Stop R/AL3 325 Broadway, Boulder, CO 80305 United States
AU: Nesbitt, S
EM: snesbitt@atmos.colostate.edu
AF: Department of Atmospheric Science, Colorado State University, 200 West Lake Street, Fort Collins, CO 80523-1371 United States
AU: Cifelli, R
EM: rob@atmos.colostate.edu
AF: Department of Atmospheric Science, Colorado State University, 200 West Lake Street, Fort Collins, CO 80523-1371 United States
AB: One of the goals of the NASA Global Precipitation Mission (GPM) is to establish ground sites that will produce precipitation estimates and uncertainties throughout columns of the atmosphere to be used as reference points for satellite precipitation algorithm development and validation. The fundamental problem with developing these columns of estimated precipitation is that different ground based instruments have different spatial and temporal resolutions as well as different measurement error characteristics. This would not be a problem if the precipitation was not varying in time and space. But since the precipitation is variable at different temporal and spatial resolutions, the uncertainties of the Quantitative Precipitation Estimate (QPE) from each instrument will be a combination of the instrument measurement error and the spatiotemporal variability of the precipitation. Thus, an important goal of the ground validation for GPM will be to quantify the measurement and sampling errors of each instrument and combine the data into an error model to evaluate the satellite algorithm performance. This study addresses the spatiotemporal variability of precipitation observed by a vertically pointing profiling radar operating at 915 MHz and the Melbourne, FL, WSR-88D NOAA weather radar located 36 km away and observing the reflectivity around the profiler site. While the profiling radar produced reflectivity estimates every minute with a vertical resolution of 100 m, the scanning radar completed volume scans every 5 minutes and had a vertical resolution over the profiler site of about 630 m. For each of the 21 rain events that occurred during the TEFLUN-B campaign (August-September 1998), the profiler 1-minute reflectivity estimates were processed to produce 5-minute mean and variance reflectivity profiles. As expected, the profiler reflectivity variance was less for stratiform rain regimes than for convective rain regimes. Also, the variance of the scanning radar reflectivity over a 10 x 10 km domain around the profiler site increased as the profiler reflectivity variance increased, demonstrating a correlation between the temporal reflectivity variance observed by a profiling radar with the spatiotemporal reflectivity variance observed by a scanning radar. The correlation provides a measure of sampling variability within different rain types that can be extended over the coverage umbrella of the scanning radar. The statistics from the 21 rain events will be presented at the conference.
DE: 3314 Convective processes
DE: 3354 Precipitation (1854)
DE: 3360 Remote sensing
DE: 3394 Instruments and techniques
SC: Hydrology [H]
MN: 2005 Joint Assembly