Unexpected increase in precipitation intensity with temperature — A result of mixing of precipitation types?

Using synoptic weather types and comparing high-resolution precipitation and temperature station data, a separation of large-scale and convective precipitation events is performed. We present percentiles of both types and their superposition for varying precipitation accumulation timescales. In some temperature ranges, large-scale, convective and total precipitation percentiles follow increases with temperature at rates higher than that of the saturation humidity increase of the atmosphere of roughly 7% per degree Kelvin — as given by the Clausius–Clapeyron (CC) relation. However, the increase in total precipitation is found to be due to the transition between the corresponding percentiles of the large-scale and convective types, rather than their individual sections of steep increase. Furthermore, convective precipitation displays a leveling-off towards higher temperatures. This poses further challenges to reconcile arguments brought forward elsewhere — namely those suggesting convective precipitation as the driver of the super-CC increase — with the present observational data.

Research highlights
► Scaling of precipitation intensity with temperature is a consequence of co-interaction between
► Precipitation types
► Neither precipitation type is constrained by the Clausius–Clapeyron rate of moisture increase
► The statistical effect is amplified with higher temporal resolution