89th American Meteorological Society Annual Meeting

Sunday, 11 January 2009
Analysis and verification of multi-sensor precipitation estimates for the Texas Coastal Bend
Phoenix Convention Center
Angelica M. Villarreal, Texas A&M University, Corpus Christi, TX; and P. E. Tissot and R. G. Hay
Poster PDF (587.8 kB)
Until the initiation of NEXRAD (Next Generation Radar) towers and MPE (multi-sensor precipitation estimator), precipitation analysis was based mostly on single point estimations. However, these systems with higher spatial resolution are vital to improve analysis and models of many precipitation driven processes. A number of studies have been conducted to evaluate the accuracy of MPE and Stage III products. The results vary by region, time, climate regime, precipitation type. To our knowledge such studies have yet to focus on the Texas Coastal Bend. The area is adjacent to the Gulf of Mexico and otherwise in a semi-arid subtropical climate. Precipitation is driven by frontal passages in the winter and by thunderstorms and sometimes tropical storms during the summers. Evaluating the accuracy of MPE estimates is important to drive models such as the prediction of indicator bacteria content in coastal recreational waters, salinity in bays and estuaries and the onset of thunderstorms. MPE data can also provide information at the local scale as to the spatial and temporal precipitation distributions and how they compare to regional averages.

The overall study area consists of a 2 degree square from 27N to 29N and 96W to 98 W, that includes a portion of the Gulf of Mexico, Corpus Christi, Victoria, Baffin Bay, and Matagorda Bay. MPE estimates are compared with rain gauge measurements from11 locations for years 1997 to 2007. The rain gauge stations were selected to cover the area from coastal to inland stations and from Northern to Southern locations. The 4km by 4km MPE area including the rain gauge stations were selected for the comparison. The results show an average difference of 7%, an average absolute difference of 21% and a maximum yearly difference of -68% for the Sarita station (1999). There are larger differences between MPE estimates and rain gauge measurements in the months from June to November. Coastal to inland and North to South differences are not significant. The yearly and seasonal MPE precipitation estimates are analyzed and compared with the published long term averages for the region. Based on MPE estimates, precipitation rates in the North East area were observed to be between 140 and 150 cm per year while the South West area has a 70 to 80 cm per year precipitation rate with a gradient aligned parallel to the coast line. No significant coastal to inland gradient was observed in the study area. Tropical storms have a significant impact on temporal and spatial distributions even on yearly and multi year scale. The MPE data is also utilized to analyze local spatial precipitation distributions and to create movies to visualize precipitation patterns during hurricanes, tropical storms, thunder storms, and frontal passages.

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