Precipitation-Temperature Scaling of 3h Convective Precipitation over Europe

The Clausius-Clapeyron (CC) equation describes the change in saturated water vapor pressure with temperature (7% per degree C within the normal temperature range). The possible effects of deviations from CC scaling, especially the so-called "super CC" scaling (increase above 7%), on the occurrence and intensity of precipitation extremes are connected to many different factors. The most important of them are the availability of moisture and more intense convection. The resulting CC scaling is influenced also by the type of precipitation and the super CC scaling may be the result/artifact coming from combination of precipitation of different types. Here, we present a study of the variability in the rates of increase in precipitation intensity with dew point temperature using the Multi Source Weighted Ensemble Precipitation (MSWEP) 3h data with the resolution of 0.1 deg. for 2006–2016 over Central Europe. The scaling is assessed for daily dew point temperature (taken from ERA5-Land dataset) and the 95th percentile of 3h precipitation using the quantile regression method. As the resulting scaling may be influenced by the type of precipitation (convective versus non-convective), we apply the method of threshold precipitation rate (THR) to categorize the precipitation in two subsets. The average scaling slopes are 8.7 %/°C for all precipitation events, 6.8 %/°C for precipitation events above THR and 3.0 %/°C for events bellow THR. The mixing of events bellow/above THR amplifies the scaling. To evaluate the scaling of convective precipitation with dew point temperature independently, we use the data of lightning occurrence from the EUCLID dataset (3h, resolution 0.1 deg.), as the lightning occurrence is assumed to be a robust proxy for convective precipitation. The average scaling slopes are 13.4 %/°C for precipitation events with lightning and 6.3 %/°C for precipitation events without lightning. The scaling of the events with lightning corresponds with the double CC scaling for convective events reported by previous studies.