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

• Published in: Atmospheric research 2013-01, Vol.119, p.56-61
• Main Authors: Berg, P., Haerter, J.O.
• Format: Article
• Language: English
• Subjects: Convection; Intensity; Precipitation; Temperature
• ISSN: 0169-8095; 1873-2895
• DOI: 10.1016/j.atmosres.2011.05.012

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. ► 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