National Weather Service Hydrology Program Objectives for JPOLE

R. Fulton
NWS Office of Hydrologic Development
October 2, 2001
 

• Implement a reliable and robust polarimetric rainfall estimation algorithm within the KOUN Open RPG that generates both existing reflectivity-based Precipitation Processing System (PPS) rainfall products (OHP, THP, STP, USP, DPA, DSP) as well as the corresponding polarimetric- based rainfall products out to 230 km range
• Quantify in side-by-side comparisons the added value of operational, polarimetric radar rainfall estimates compared to existing PPS estimates and observed point-wise and basin-wide rain gauge and streamflow data for a variety of seasons (identify times/places/situations when they are improved and when they are degraded)
• Prove no degradation of rainfall estimation accuracy and timeliness (<= 5 minute VCPs) relative to reflectivity-based rainfall estimates
• Demonstrate improved stream flow forecasting for river flooding and increased flash flood warning lead time due to improved polarimetric QPEs
• Collect polarimetric radar rainfall data continuously for at least a year for input into operational hydrologic models (these continuous models require knowledge of rainfall and antecedent soil moisture conditions for all rain events with no gaps)
• Improve performance consistency of multiparameter rainfall estimators over the full spectrum of rainfall systems (intense convection, weak stratiform, ...)
• Demonstrate reduced point and areal rainfall biases and improved correlations at both short (hourly or less) and long time scales for all rainfall types and drop size distributions without regard to any temporal evolution of hydrometeor microphysics (hydrologic models depend on unbiased QPEs at short time scales, not just for entire storm periods)
• Alleviate limitations of current reflectivity-based algorithms caused by hail contamination to improve flash flood monitoring (alleviate need for arbitrary maximum reflectivity thresholds used to limit hail-related radar overestimation)
• Improve radar data quality (reduce rainfall contamination by anomalous propagation, ground clutter, and other non-meteorological echoes)
• Evaluate range performance of polarimetric rainfall estimates and techniques to correct for nonuniform vertical profiles of polarimetric measurements (evaluate vertical variability of polarimetric measurements, quantify maximum effective QPE range as a function of season, evaluate possible impacts of attenuation)
• Collect polarimetric radar rainfall data and run operational hydrologic models for at least several well-instrumented hydrologic basins (preferably calibrated, unregulated basins with hourly or better stream flow and rain gauge data) located both near and far from the radar to evaluate the hydrologic impacts of QPE range effects
• Quantify added value of operational polarimetric rainfall estimates under partial beam blockage situations (how does partial blockage impact Zdr and Kdp measurements?)
• Quantify improvements to QPEs when utilizing real-time, operationally-available rain gauge data (and subsets thereof) to calibrate polarimetric rainfall estimates
• Demonstrate improvements to snowfall estimation (liquid water equivalent and snow depth)
• Provide reliable estimates of locations of liquid vs. solid precipitation for hydrologic runoff models (rain vs. snow)