Abstract
An analysis was performed between a WSR-88D's precipitation estimation capability and a rain gauge network. The WSR-88D is located in League City, TX, and the rain gauge network is in Harris County, TX. Relevant data were collected for nine different case events. These events were classified into one of three weather system classifications. The classifications were based on two criteria, synoptic conditions and the storms radar signature. Radar data were collected from five levels above the surface. These levels included 1.0 1.5@ 2.0 @ 2.5 km, and 3.0 km. Radar precipitation estimates were calculated at each 1.4 2 level using Z = 30ORand Z = 25OR" . The precipitation amounts, as measured by both the gauges and the radar,were used to calculate corresponding differences between the amounts. Two percentage adjustments for each Z-R relationship were calculated to account for these differences. The first percentage adjustment was a constant weighted mean percentage adjustment, and the second a linear percentage adjustment. In general, for all nine cases, the 30OR 1.4 was an underestimate of rainfall, and the 25OR" 2 was an overestimate of rainfall. The 30OR 1.4 had an optimum estimation accuracy for the lower precipitation amounts, whereas the 25OR 1,2 had an optimum accuracy for the higher precipitation amounts. The organized convection class was well supported by the data as a unique identifiable classification, and the most accurate radar estimates were derived using Z = 30OR 1.4 linear percentage adjustments. The unorganized convection class and the stratiform with isolated convection class were strongly classified only after being combined into one class. For this combined class, the Z = 25OR 1.2 linear percentage adjustments produced optimum radar estimates of precipitation.
Gleason, Byron Edward (1997). An analysis of radar estimated precipitation to rain gauge measurements. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1997 -THESIS -G543.