ESRL/PSD Seminar Series

The Use of Radar to Improve Rainfall Estimation over the Tennessee and San Joaquin River Valleys

Larry Carey
Earth System Science Center (ESSC) / University of Alabama in Huntsville


Frequent, widespread, and accurate estimates of rainfall are necessary for weather forecasting, agricultural planning, water and river management and many other activities essential to our daily quality of life. The professional standard in hydrology and meteorology for accurately measuring point rainfall is the rain gauge. Maintaining a large network of rain gauges for the measurement of areal rainfall can be labor intensive and very expensive. A complementary approach to estimating rainfall over a large area is afforded by weather radar. Each approach has its strengths and weaknesses. Because of various technical challenges, the routine operational use of radar-based rainfall estimates has been fairly limited in meteorology and especially hydrology up until recently. To explore the potential of radar in hydrometeorology, an ongoing collaborative R&D project between the Tennessee Valley Authority (TVA), The Von Braun Center for Science & Innovation (VCSI), Inc., NASA Marshall Space Flight Center (MSFC), and the University of Alabama in Huntsville (UAHuntsville) was initiated to develop radar-based rainfall estimates for operational use in daily management of the Tennessee River System by the TVA. The UAHuntsville-NASA Advanced Radar for Meteorological and Operational Research (ARMOR, C-band polarimetric) was first utilized in a demonstration research project that later evolved into a research-to-operations effort over a larger domain using the operational next-generation radar (NEXRAD, S-band) network. During several phases of this project, the team developed and refined the ARMOR and NEXRAD Rainfall Estimation Processing Systems or AREPS and NREPS, respectively. In this presentation, I will overview the motivation, general approach, testing and practical experience with AREPS and NREPS over the Tennessee Valley. I will highlight specific challenges associated with developing these operational tools for TVA, including software system, communication network, user-developer education, radar meteorology and rain gauge/validation issues. More recently, we have begun to adapt and improve NREPS to provide useful rainfall estimates in the more mountainous eastern portion of the Tennessee River Basin. In addition, we have recently configured NREPS to support a larger NASA project to create prototype hardware/software infrastructure to improve water management in the San Joaquin River watershed in California. I'll discuss our ongoing efforts to improve the mitigation of non-precipitation echo and generally reduce the impact of terrain on NREPS performance. Finally, I'll highlight some of our remaining science-to-operations challenges associated with radar rainfall estimation, especially over California with its unique precipitation and varied terrain, where the NOAA Hydrometeorology Testbed (HMT) has considerable research experience, knowledge and capabilities from which we hope to learn and improve NREPS.

Friday, Oct 15 2010

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