QUANTIFYING CHANGES IN EXTREME PRECIPITATION AT HOUSTON AND OKLAHOMA CITY BY 2041-2065 USING THE CANADIAN REGIONAL CLIMATE MODEL (CRCM)

摘要

One-half-degree gridded daily-projection precipitation model output from two combinations of theCanadian Regional Climate Model (CRCM)—one driven by the Community Climate System Model (CCSM) andanother by the Canadian Global Climate Model 3 (CGCM3)—was obtained from the North American RegionalClimate Change Assessment Program (NARCCAP). Gridded observational daily precipitation data were usedas a reference to a 1971-1995 historic period and as a basis for validating the projection data. Validationsuggested strong bias in the projection data, which necessitated that they be bias-corrected using a mean-valuetechnique. Both the observational and projection data were ranked and assigned percentile values as a meansof identifying and quantifying possible changes in extreme precipitation during a historic 1971-1995 and a future2041-2065 period over two 1/2-degree grid squares centered over Houston and Oklahoma City. Overall resultsof the percentile analysis suggested that, for the highest percentile rankings, the daily precipitation valuesassociated with a given percentile ranking will increase by the 2041-2065 period. For more moderate percentilerankings, the tendency toward change was less clear. For lower percentile rankings (approximately the 80th),there was indication that the values associated with a given percentile ranking will decrease by the futureperiod. Analysis also suggested that a more sophisticated bias-correction procedure based on rain rate isnecessary.