Interpretation of regional variation of extreme values of point precipitation in Denmark

The regional variation of extreme values of peak intensity and total depth of rain events from 37 high resolution gauges in Denmark was studied. A statistical test indicated that a significant regional variation is present for return periods smaller than 1 yr and perhaps also for longer return periods. Regional variables including local and regional measures of topography as well as measurements from a more dense rain gauge network with daily observations were investigated to identify covariates that are able to explain the regional variation. The identified covariates were the annual average precipitation and the rain depth corresponding to a 0.2-yr return period estimate at the denser network. Least squares regression on these two variables describes a significant part of the variation of the extreme values for return periods up to 0.5 yr. The regional variation of the extreme values cannot be explained for return periods longer than 1 yr. The residuals show significant variation fur the extreme values with a return period of 0.1 yr.