NOAA's NEXRAD Reprocessing Effort — Bias assessment and adjustment of a long term high resolution quantitative precipitation estimates

The processing of radar-only precipitation via the reanalysis from the National Mosaic and Multi-Sensor Quantitative(NMQ/Q2) based on the WSR-88D Next‐generation Radar (NEXRAD) network over Continental United States (CONUS) is completed for the period covering from 2001 to 2012. Reanalysis data are available at 1-km and 5-minute resolution. An important step in the process of generating the best possible precipitation estimates is to assess the bias in the radar-only product and to implement techniques for merging in situ data providing the best bias-adjusted estimates .

We use a combination of rain gauge networks to assess the bias in the NMQ reanalysis data. Rain gauge networks such as the Hydrometeorological Automated Data System (HADS), the Automated Surface Observing Systems (ASOS), the Climate Reference Network (CRN), and the Global Historical Climatology Network Daily (GHCN-D) are combined for use in the assessment. The challenge is to find the right combination and number of rain gauges to assess the bias at the finest resolution possible. In addition we are implementing techniques for merging of in-situ data sets and the radar only estimates such as Inverse distance weighting (IDW), Ordinary Krigging, (OK) and Conditional Bias Penalized Krigging (CBPK). As evaluation of these methods is presented at the CONUS scale for the reanalysis period.