Evaluation and projected changes of precipitation statistics in convection-permitting WRF climate simulations over Central Europe

Abstract

We perform simulations with the WRF regional climate model at 12 and 3 km grid resolution for the current and future climates over Central Europe and evaluate their added value with a focus on the daily cycle and frequency distribution of rainfall and the relation between extreme precipitation and air temperature. First, a 9 year period of ERA-Interim driven simulations is evaluated against observations; then global climate model runs (MPI-ESM-LR RCP4.5 scenario) are downscaled and analyzed for three 12-year periods: a control, a mid-of-century and an end-of-century projection. The higher resolution simulations reproduce both the diurnal cycle and the hourly intensity distribution of precipitation more realistically compared to the 12 km simulation. Moreover, the observed increase of the temperature-extreme precipitation scaling from the Clausius-Clapeyron (C-C) scaling rate of ~ 7% K −1 to a super-adiabatic scaling rate for temperatures above 11 °C is reproduced only by the 3 km simulation. The drop of the scaling rates at high temperatures under moisture limited conditions differs between sub-regions. For both future scenario time spans both simulations suggest a slight decrease in mean summer precipitation and an increase in hourly heavy and extreme precipitation. This increase is stronger in the 3 km runs. Temperature-extreme precipitation scaling curves in the future climate are projected to shift along the 7% K −1 trajectory to higher peak extreme precipitation values at higher temperatures. The curves keep their typical shape of C-C scaling followed by super-adiabatic scaling and a drop-off at higher temperatures due to moisture limitation.

Convective Shower Characteristics Simulated with the Convection-Permitting Climate Model COSMO-CLM

“…is overestimated by 6%. The overestimation of convective precipitation in mountainous areas is in line with results in Knist et al [30], who performed convection-permitting climate simulations over Germany using the WRF-model and compared the results to gauge data. Figure 7 shows the spatial distribution of the occurrence of convective cells.…”

“…However, it cannot be ruled out that other model deficiencies contribute to this bias. The difference in representing convective precipitation in mountainous areas and lowland regions agrees with an evaluation of the WRF-CPM [30]. The fact that both models overestimate convective precipitation in the mountains whilst giving correct amounts in the lowlands might indicate a general, model-independent problem, such as resolution, which is 2.8 km in both studies.…”

Subhourly rainfall in a convection-permitting model

“…Extensive work evaluating hourly precipitation in CPMs [3, 7-10, 12, 13] has enabled a growing number of CPM studies of future hourly precipitation [18,[56][57][58] and given confidence in the resulting projections. To date, this has not been the case with subhourly CPM precipitation.…”

A new high‐resolution Meteorological Reanalysis Italian Dataset: MERIDA

“…The model was configured with 32 vertical levels, a Yonsei F I G U R E 2 Modelling chain for the production of MERIDA University (YSU) planetary boundary-layer (PBL) scheme , a Rapid Radiative Transfer Model for GCMs (RRTMG) scheme for radiation (Iacono et al, 2008), a Grell and Dévényi cumulus scheme (Grell and Dévényi, 2002), WRF single-moment 5-class (WSM5) microphysics (Lim and Hong, 2010) and National Centers for Environmental Prediction NCEP/Noah as land surface scheme (Ek et al, 2003). More recently, also convection-permitting high-resolution simulations (3 km and 50 vertical levels) were carried out in climate mode with a very similar configuration but for a smaller domain covering central Europe and only the northern part of Italy (Knist et al, 2018).…”