Hindcast regional climate simulations within EURO-CORDEX: evaluation of a WRF multi-physics ensemble

Abstract

Abstract. In the current work we present six hindcast Weather Research and Forecasting (WRF) simulations for the EURO-CORDEX domain with different configurations in microphysics, convection and radiation for the time period 1990–2008. All regional model simulations are forced by the ERA-Interim reanalysis and have the same spatial resolution (0.44°). These simulations are evaluated for surface temperature, precipitation, short- and longwave downward radiation at the surface and total cloud cover. The analysis of the WRF ensemble indicates systematic biases in both temperature and precipitation linked to different physical mechanisms for the summer and winter season. Overestimation of total cloud cover and underestimation of downward shortwave radiation at the surface, mostly when using Grell–Devenyi convection and the CAM radiation scheme, intensifies the negative summer temperature bias in northern Europe (max −2.5 °C). Conversely, a strong positive downward shortwave summer bias in central (40–60%) and southern Europe mitigates the systematic cold bias in WRF over these regions, signifying a typical case of error compensation. Maximum winter cold bias is over north-eastern Europe (−2.8 °C); this location is indicative of land–atmosphere rather than cloud-radiation interactions. Precipitation is systematically overestimated in summer by all model configurations, especially the higher quantiles, which are associated with summertime deep cumulus convection. The Kain–Fritsch convection scheme produces the larger summertime precipitation biases over the Mediterranean. Winter precipitation is reproduced with lower biases by all model configurations (15–30%). The results of this study indicate the importance of evaluating not only the basic climatic parameters of interest for climate change applications (temperature-precipitation), but also other components of the energy and water cycle, in order to identify the sources of systematic biases, possible compensatory or masking mechanisms and suggest methodologies for model improvement.

Land‐atmosphere coupling in EURO‐CORDEX evaluation experiments

“…[] and Katragkou et al . []. In addition to these main settings, the models also differ, e.g., in the configuration of the lateral boundary relaxation zone around the EURO‐CORDEX focus domain, the number of vertical levels, or interpolation settings for initial and static fields.…”

“…For the subset of WRF simulations within the EURO‐CORDEX ensemble Katragkou et al . [] evaluated shortwave and longwave radiation and cloud cover and their relation to temperature and precipitation biases. In an evaluation study on the added value of increased spatial resolution on the reproduction of precipitation extremes, Prein et al .…”

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

“…Both use WSM-5 microphysics (Hong et al 2004), RRTMG radiation (Iacono et al 2008), the YSU PBL scheme (Hong et al 2006) and the NOAH land surface model (Ek et al 2003). This choice of setup results from several validation studies of WRF Euro-CORDEX evaluation simulations (Kotlarski et al 2014;García-Díez et al 2015;Katragkou et al 2014). Since the 3 km domain is directly nested into the EUR-11 domain, both simulation types share the same boundary conditions for Central Europe.…”

Ammonia Concentrations Over Europe – Application of the WRF-Chem Model Supported with Dynamic Emission

“…The model performance for meteorology affects both the air quality results and the calculated emissions. Several studies focused on all of Europe and reported biases for both air temperature and precipitation (Miglietta et al [37], Katragkou et al [38], Wałaszek et al [39], Kim et al [40], and Warrach-Sagi et al [41]). Recent findings provided by Skjøth et al [42] show that the bias in air temperature at 2 m varies spatially and seasonally.…”