Can National Weather Service Spatially Gridded Radar Precipitation Estimates be Used to Overcome Spatial Variability in Mississippi Precipitation Measurements?

Author(s): Thornton, R.; Sassenrath, G.; Schneider, J.; Corbitt, J.; Schmidt, A.; Crumpton, J.; Rice, B.; van Riessen, H.; Prabhu, R.

The goal of this research is to determine how reliable National Weather Service (NWS) spatially gridded radar precipitation estimates are in Mississippi. If results are good, the plan is to incorporate this source of rainfall information into the Mississippi Irrigation Scheduling Tool (MIST). Several rain gauge sources are included in the analysis in order to increase the spatial resolution of precipitation across the state of Mississippi. These sources include The Community Collaborative Rain, Snow and Hail Network (CoCoRahs), National Weather Service Cooperative Observers (COOP) and one DREC station. These rain gauge values were obtained for July 1-31 2012. Each rain gauge location is referenced by latitude and longitude, so it can be compared to NWS radar precipitation estimates at the same coordinates.

Summertime precipitation in Mississippi demonstrates a high degree of spatial variability through pop-up afternoon showers and thunderstorms. This research will determine the usefulness of radar-estimated precipitation, the spatial context of which could eliminate the variability problem inherit in point-source measurements. Actual rain gauge values are compared to radar-estimated values through the use of ARCGIS. If it is determined that radar-estimated precipitation is comparable to actual rain gauge data, then this will be incorporated into a tool to aid the Mississippi agricultural community in knowing when to most efficiently irrigate. The analysis will also attempt to find any spatial bias present between the two measurements, resulting in the discovery of any consistent correction coefficients. This, along with other conservation efforts already in place, will potentially help Mississippi farmers to conserve groundwater by supporting recharge of the Mississippi River Shallow Alluvial Aquifer over time.

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