Thursday, 14 January 2016
Through a closely collaborative effort with OHD and ESRL, NCEP Environmental Modeling Center has developed Climatology-Calibrated Precipitation Analysis (CCPA), a precipitation analysis at about 5km resolution with 6 hour accumulation over the Contiguous United States (CONUS). Utilizing linear regression and spatial temporal downscaling techniques, this 6-hourly analysis product is generated by combining two widely used datasets by taking advantage of the higher reliability of the NCEP CPC Unified Global Daily Gauge Analysis and the higher temporal and spatial resolution of the NCEP EMC Stage IV multi-sensor quantitative precipitation estimations (QPEs). CCPA has been running operationally in real-time since July 2010. The product is available to users at five basic grids from 2002 to present. In 2011 at the request of users, the 3-hourly analysis was developed and successfully implemented within the CCPA production suite. The CCPA product is being widely used in research and applications for precipitation verification, bias correction and downscaling. At EMC CCPA provides a proxy of truth for the bias correction and statistical downscaling of precipitation forecasts from the NCEP GFS Ensemble Forecast System (GEFS) and Short Range Ensemble Forecast System (SREF) products, and precipitation verifications in evaluating the performance of various forecast systems.
An upgrade to the version 3 of CCPA (CCPAv3) is undergoing and scheduled for operational implementation at NCEP in fall 2015. With the new version CCPA will be improved and expended. The upgrade includes: 1) updating the regression coefficients with extended historical training data sets from 2002 to 2014, which is the most important enhancement to CCPA; 2) change to 3-hourly CCPA due to poor data quality of Stage IV hourly data in the CNRFC area, using Stage II hourly in both NWRFC and CNRFC instead of NWRFC only, while using Stage IV hourly in remaining areas of CONUS as weights to produce 3-hourly CCPA; 3) extension of CCPA look-back period by following Stage IV update schedule in recent implementation of the RTMA/URMA upgrade, and thus by making additional runs at 1/3/5/7 days past the valid date; 4) inclusion of 2.5 km NDGD grid analysis. In this presentation, all enhancements will be described, evaluated and validated. Especially comparison of both the original and new products against rain gauge observations will be performed and a summary of the presentation and results will be shown.
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