This study summarizes the revision performed on the surface layer formulation of the Weather Research and Forecasting (WRF) model. A first set of modifications are introduced to provide more suitable similarity functions to simulate the surface layer evolution under strong stable/unstable conditions. A second set of changes are incorporated to reduce or suppress the limits that are imposed on certain variables in order to avoid undesired effects (e.g., a lower limit in u * ). The changes introduced lead to a more consistent surface layer formulation that covers the full range of atmospheric stabilities. The turbulent fluxes are more (less) efficient during the day (night) in the revised scheme and produce a sharper afternoon transition that shows the largest impacts in the planetary boundary layer meteorological variables. The most important impacts in the near-surface diagnostic variables are analyzed and compared with observations from a mesoscale network.

The observed trend towards warmer and drier conditions in southern Europe is projected to continue in the next decades, possibly leading to increased risk of large fires. However, an assessment of climate change impacts on fires at and above the 1.5 °C Paris target is still missing. Here, we estimate future summer burned area in Mediterranean Europe under 1.5, 2, and 3 °C global warming scenarios, accounting for possible modifications of climate-fire relationships under changed climatic conditions owing to productivity alterations. We found that such modifications could be beneficial, roughly halving the fire-intensifying signals. In any case, the burned area is robustly projected to increase. The higher the warming level is, the larger is the increase of burned area, ranging from ~40% to ~100% across the scenarios. Our results indicate that significant benefits would be obtained if warming were limited to well below 2 °C.

Ambitious climate change mitigation plans call for a significant increase in the use of renewables, which could, however, make the supply system more vulnerable to climate variability and changes. Here we evaluate climate change impacts on solar photovoltaic (PV) power in Europe using the recent EURO-CORDEX ensemble of high-resolution climate projections together with a PV power production model and assuming a well-developed European PV power fleet. Results indicate that the alteration of solar PV supply by the end of this century compared with the estimations made under current climate conditions should be in the range (−14%;+2%), with the largest decreases in Northern countries. Temporal stability of power generation does not appear as strongly affected in future climate scenarios either, even showing a slight positive trend in Southern countries. Therefore, despite small decreases in production expected in some parts of Europe, climate change is unlikely to threaten the European PV sector.

The European CORDEX (EURO-CORDEX) initiative is a large voluntary effort that seeks to advance regional climate and Earth system science in Europe. As part of the World Climate Research Programme (WCRP)-Coordinated Regional Downscaling Experiment (CORDEX), it shares the broader goals of providing a model evaluation and climate projection framework and improving communication with both the General Circulation Model (GCM) and climate data user communities. EURO-CORDEX oversees the design and coordination of ongoing ensembles of regional climate projections of unprecedented size and resolution (0.11 • EUR-11 and 0.44 • EUR-44 domains). Additionally, the inclusion of empiricalstatistical downscaling allows investigation of much larger multi-model ensembles. These complementary approaches provide a foundation for scientific studies within the climate research community and others. The value of the EURO-CORDEX ensemble is shown via numerous peer-reviewed studies and its use in the development of climate services. Evaluations of the EUR-44 and EUR-11 ensembles also show the benefits of higher resolution. However, significant challenges remain. To further advance scientific understanding, two flagship pilot studies (FPS) were initiated. The first investigates local-regional phenomena at convection-permitting scales over central Europe and the Mediterranean in collaboration with the Med-CORDEX community. The second investigates the impacts of land cover changes on European climate across spatial and temporal scales. Over the coming years, the EURO-CORDEX community looks forward to closer collaboration with other communities, new advances, supporting international initiatives such as the IPCC reports, and continuing to provide the basis for research on regional climate impacts and adaptation in Europe.

In this study we examine the Urban Heat Island (UHI) of Granada. First, we perform a study of the evolution of the recorded temperatures at a meteorological station over the last century. In this record, the minimum temperatures increase while the maximum temperatures decrease. We also compare both rural and urban temperature records, obtaining the UHI fluctuations on a smaller time scale. The results show that the UHI phenomenon is stronger in winter, and the maximum difference occurs in early morning when temperatures are at their daily minimum. Then, we examine the geographical distribution of temperature in the urban region and obtain the dependence of UHI form on meteorological conditions, urban geometry and time scale. Urban geometry plays a particular role in the UHI form. The formation of UHI phenomena depends mainly on weather conditions and on time of night. Finally, we relate both UHI form and intensity with the observed trends in the urban time series.

This study analyzes the daily-mean surface wind variability over an area characterized by complex topography through comparing observations and a 2-km-spatial-resolution simulation performed with the Weather Research and Forecasting (WRF) model for the period 1992-2005. The evaluation focuses on the performance of the simulation to reproduce the wind variability within subregions identified from observations over the 1999-2002 period in a previous study. By comparing with wind observations, the model results show the ability of the WRF dynamical downscaling over a region of complex terrain. The higher spatiotemporal resolution of the WRF simulation is used to evaluate the extent to which the length of the observational period and the limited spatial coverage of observations condition one's understanding of the wind variability over the area. The subregions identified with the simulation during the 1992-2005 period are similar to those identified with observations (1999)(2000)(2001)(2002). In addition, the reduced number of stations reasonably represents the spatial wind variability over the area. However, the analysis of the full spatial dimension simulated by the model suggests that observational coverage could be improved in some subregions. The approach adopted here can have a direct application to the design of observational networks.

Europe is investing considerably in renewable energies for a sustainable future, with both Iberian countries (Portugal and Spain) promoting significantly new hydropower, wind, and solar plants. The climate variability in this area is highly controlled by just a few large-scale teleconnection modes. However, the relationship between these modes and the renewable climate-dependent energy resources has not yet been established in detail. The objective of this study is to evaluate the impact of the North Atlantic Oscillation (NAO) on the interannual variability of the main and primary renewable energy resources in Iberia. This is achieved through a holistic assessment that is based on a 10-km-resolution climate simulation spanning the period 1959-2007 that provides physically consistent data of the various magnitudes involved. A monthly analysis for the extended winter (October-March) months shows that negative NAO phases enhance wind speeds (10%-15%) and, thereby, wind power (estimated around 30% at typical wind-turbine altitudes) and hydropower resources (with changes in precipitation exceeding 100% and implying prolonged responses in reservoir storage and release throughout the year), while diminishing the solar potential (10%-20%). Opposite signals were also sporadically identified, being well explained when taking into account the orography and the prevailing wind direction during both NAO phases. An additional analysis using real wind, hydropower, and solar power generation data further confirms the strong signature of the NAO.

[1] We present an analysis of the sensitivity to different physical parameterizations of a high-resolution simulation of the MM5 mesoscale model over the Iberian Peninsula. Several (16) 5-year runs of the MM5 model with varying parameterizations of microphysics, cumulus, planetary boundary layer and longwave radiation have been carried out. The results have been extensively compared with observational precipitation and surface temperature data. The parameterization uncertainty has also been compared with that related to the boundary conditions and the varying observational data sets. The annual cycles of precipitation and surface temperature are well reproduced. The summer season presents the largest deviations, with a 5 K cold bias in the southeast and noticeable precipitation errors over mountain areas. The cold bias seems to be related to the surface, probably because of the excessive moisture availability of the five-layer soil scheme used. No parameterization combination was found to perform best in simulating both precipitation and surface temperature in every season and subregion. The Kain-Fritsch cumulus scheme was found to produce unrealistically high summer precipitation. The longwave radiation parameterizations tested were found to have little impact on our target variables. Other factors, such as the choice of boundary conditions, have an impact on the results as large as the selection of parameterizations. The range of variability in the MM5 physics ensemble is of the same order of magnitude as the observational uncertainty, except in summer, when it is larger and probably related to the inaccuracy of the model to reproduce the summer precipitation over the area.