Regional precipitation quantile values for the continental United States computed from L-moments

Abstract

Precipitation quantile values have been computed for 9 probabilities, 8 durations, 12 starting months, and 111 regions across the US. L-moment methodology has been used for the calculations. Discussed are the rationale for selecting the Pearson type III (gamma) and Wakeby distributions, and the confidence that can be placed in the quantile values. Results show that distribution functions become more asymmetrical as the duration decreases, indicating than the median may be a better measure of central tendency that the mean. Portraying the quantile values as a percentage of the median value leads to smooth spatial fields. Computation of quantile values was the first known large-scale application of L-moment methodology. -from Authors