A case study of possible future summer convective precipitation over the UK and Europe from a regional climate projection

Climate change caused by green house gas emissions is now following the trend of rapid warming consistent with a RCP8.5 forcing. Climate models are still unable to represent the mesoscale convective processes that occur at resolutions similar to O(3 km) and are not capable of resolving precipitation patterns in time and space with sufficient accuracy to represent convection. In this article, the UK Met Office precipitation observations are compared with the simulations for the period 1990-1995 followed by a simulation of a near-future period 2031-2036 for a regional nested weather model. The convection-permitting model, resolution similar to O(3 km), provides a good correspondence to the observational precipitation data and demonstrates the importance of explicit convection for future summer precipitation estimates. The UK summer precipitation is reduced slightly (similar to 10%) for 2031-2036 and there is no evidence of an increase in the peak maximum hourly precipitation magnitude. A similar pattern is observed over the whole European inner model domain. The results using the Kain-Fritsch convective parameterization scheme at a resolution similar to O(12 km) in the outer domain increase summer precipitation by similar to 10% for the UK. The average precipitation rate per event increases, dry periods extend and wet periods shorten. As part of the change, 10-m winds of <3 ms(-1) become more common - a scenario that would impact on power generation from wind turbines through calmer conditions and cause more frequent pollution episodes.