Hot Items 2004NEXRAD PMC approves polarimetric upgrade to WSR-88D radar network
For more than 20 years, NSSL has been a leader and major contributor to the scientific and engineering development of polarimetric weather radar. This long history of accomplishment was rewarded in the fall of 2003 when the NEXRAD Program Management Committee (PMC) approved taking the first step towards upgrading the operational WSR-88D network to include polarimetric capabilities. This PMC decision, based on results from the year-long Joint Polarization Experiment (JPOLE), represents a significant milestone in the continuing evolution of the WSR-88D radar network.
JPOLE Data Collection and Analysis
JPOLE, which was conducted from the Spring of 2002 through the Spring of 2003,
was designed to test the proof-of-concept polarimetric KOUN WSR-88D radar
engineering design, evaluate radar data quality, demonstrate the utility
and feasibility to operational users, and collect data and information that
could be used to perform a cost/benefit analysis.
The KOUN data archive from JPOLE contains an unprecedented collection of exceptional quality polarimetric measurements of 98 events containing meteorological and non-meteorological data. Using this data set, analyses were conducted to demonstrate KOUN's ability to provide improved Quantitative Precipitation Estimates, discriminate between hydrometeor types, and eliminate non-meteorological artifacts. Fainfall estimation was found to be dramatically improved in terms of both bias and RMS (root mean square) error while classification algorithms demonstrated great skill at pinpointing the location of hail within storms, discriminating between snow and rain, identifying the location of strong tornadoes, and improving data quality.
Operational Evaluation
The utility of polarimetric data to operational forecasters was also examined
during JPOLE. A KOUN scanning strategy was designed to emulate the elevation
angles, scanning rates, and volume coverage times used by standard WSR-88D
radars. Real-time polarimetric data and products were then supplied to forecasters
at the National Weather Service Forecast Office in Norman, Okla. NSSL observers
assisted the forecasters in the analysis and interpretation of the polarimetric
radar data and products during the intense three-month data collection period
in the spring of 2003. In several instances, KOUN data and products provided
value-added information to the warning decision process. For example, results
of the polarimetric rainfall accumulation algorithm provided flash flood
warning guidance during several heavy rain events. Hydrometeor classification
algorithm output were used to discriminate precipitation types in winter
storms and identify the location of hail in severe convective storms.
Network Upgrade
Several NSSL reports documenting JPOLE data collection and operations, improvements
in data quality, hydrometeor discrimination, rainfall estimation, and evaluation
of the engineering design are available on the JPOLE Web site.
The polarimetric upgrade of the WSR-88D network, supported by the NWS, the Federal Aviation Administration, and the Air Force Weather Agency through the NEXRAD Product Improvement Program, may ultimately prove as significant as the nationwide upgrade to Doppler radar in the 1980's. The first phase of the deployment will utilize results obtained from JPOLE to prepare system specification and identify procurement procedures needed to move towards the pre-production state of the polarimetric upgrade, eventually leading to full production.
http://cimms.ou.edu/~schuur/jpole
5/12/2004