The EURO-Med-CORDEX Flagship Pilot Study (FPS) on Convection Permitting climate modelling (CPCM) is an initiative which aims at investigating convective-scale events, their processes and changes in key regions (initially, the Alps) of Europe and the Mediterranean using high horizontal resolution models. As a contribution to FPS CPCM, in this work we evaluate the sensitivity of the simulated climate to land use and lake surface temperature representation. The work is carried out using the Weather Research and Forecasting (WRF) modelling system, version 3.8.1, configured to use the WRF Single moment 5-class microphysics scheme, Yonsei University (YSU) non-local closure PBL scheme, Rapid Radiative Transfer Model (RRTMG) radiation scheme and the Global/Regional Integrated Modelling System (GRIMS) scheme for shallow convection. The model is coupled to the Noah land surface model. The Alpine region is covered by a high resolution (0.0275o regular on a rotated lon-lat grid, ~3 km), convection-resolving domain, nested into the standard 0.11o EURO-CORDEX domain. In the latter, we used a Kain-Fritsch mass flux scheme to represent convective processes. All sensitivity simulations were forced by the ERA-Interim reanalysis. In order to investigate the sensitivity of the model to the land use distribution, a widely used dataset provided with WRF (based on USGS) was replaced with a newer, more detailed data set (based on CORINE), which has been re-mapped to keep the same land use categories of the former (Pineda et al., 2004), thus testing only the sensitivity to the new soil distribution. The differences between both datasets (Figure 1a vs 1b) consist mainly on an increase of urban areas and croplands, due to changes over time (1993 vs. 2012). In addition, some differences are produced by corrections on some categories, such as areas with changes between evergreen and deciduous forests.
Figure 1: a) Land use categories from the USGS data set over the Alpine domain. b) as (a) but for CORINE re-mapped to USGS types.
At high resolution in this area, lakes represent an important surface coupling process. None of the lakes in the alpine area are resolved by ERA-Interim, therefore, lake surface temperature needs to be carefully initialized and, ideally, dynamically represented by a lake model (Mallard et al., 2015). In this work we test the effect of two alternatives to SST nearest neighbour interpolation: initialization using daily-average surface air temperature and a model representing a more complex lake dynamics. Acknowledgement: this work is supported by the Spanish government through grant BES-2016-078158 and MINECO/FEDER co-funded projects MULTI-SDM (CGL2015-66583-R) and INSIGNIA (CGL2016-79210-R).
Tweets by SantanderMeteo
