03–05–10: Increasing Extreme Precipitation In A Warming Climate
Events of extreme precipitation have a huge influence on society, and it is commonly expected that precipitation extremes will increase as the climate warms. The basic physical cause for this is that warmer air can hold more moisture.
Geert Lenderink and Erik van Meijgaard have recently published a new study on the relation between temperature, atmospheric moisture and summertime precipitation extremes in observations and model results. They elaborate on their earlier findings reported in Nature Geoscience from measurements taken at De Bilt that extreme hourly precipitation rates increase faster with temperature than can be expected from basic physics: the famous Clausius-Clapeyron relation. They found a 14% increase per degree, which is twice the rate expected from Clausius-Clapeyron.
Dependencies of different extreme percentiles (90th-99.9th) of the distribution of observed hourly precipitation on temperature in four different data sets (De Bilt: source KNMI; Ukkel: source RMI; Bern, Basel and Zurich: source MeteoSwiss, NL: source KNMI). The gray shading plotted for the 99.9th and 99th percentiles denotes the 90% confidence intervals estimated by the bootstrap. Solid lines are percentiles computed from the raw data, whereas dotted lines are computed from the GPD fit. Exponential relations given by a 7% and a 14% increase per degree are given by the black and red stippled lines, respectively. Note the logarithmic y-axis.
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