Thursday, 13 January 2005
Rainfall Climatology of the Monsoon Season in New Mexcio: Observations from NEXRAD Stage III (1996-2003)
New Mexico’s summer monsoon rainfall (June, July, August, and September) is a part of the North American Monsoon (NAM). There are limitations of the predictability of monsoon seasonal precipitation over North America, especially on intraseasonal-to-seasonal time scales. To improve the prediction of monsoon precipitation, it is extremely important to understand and map the variability of intraseasonal, seasonal, and annual precipitations. The National Weather Service (NWS) NEXRAD (NEXt generation RADar) provides high spatial (~4 km) and temporal (hourly) resolution of pixel-averaged rainfall over the continental Unites States. This dataset has many advantages over point-based rain gauge observations, since sparse gauge measurements have difficulty in capturing the higher spatial and temporal variability of the monsoon rainfall. This study utilizes an 8-year record of NEXRAD Stage III data set (1996-2003) to reconstruct the climatology of the summer monsoon season for New Mexico. Intraseasonal-to-seasonal variations of rainfall amount, probabilities of rainfall occurrence, maximum hourly rainfall rate for the 8 year period have been derived from the NEXRAD hourly datasets. We have also determined the 8-year climatology of rainfall amount and probability of rainfall occurrence during the New Mexico summer monsoon. Detailed statistical analyses of these derived datasets at the scale of the State of New Mexico and its eight climate divisions have been carried out. To explore the advantages of NEXRAD data as a climatological product, we have made comparisons to the PRISM (Parameter-elevation Regressions on Independent Slopes Model) and NOAA Atlas 14 products over the study region. Results from this study lead to better understanding of the spatial-temporal distribution of monsoon rainfall obtained from long-term weather radar observations.