The VERSUS project was launched in January 2016 and is funded for four years. It is a transversal research project that uses a combination of different techniques, approaches and branches of knowledge (numerical modelling, satellite data, terrestrial meteorological and air quality data, and field measurements conducted specifically for this project along a coastal valley of Valencia, Spain) to answer the following two questions:

• Is it possible to improve the surveillance and early warning systems on environmental (atmospheric) risks like extreme temperatures, torrential rains and high-pollution events, identifying some “key” observables? If so , which ones are they?
• To what extent can changes in land cover at local/regional scales cause changes in rainfall patterns at different meteorological scales (meso-alpha to meso-gamma) in the Western Mediterranean Basin?

To give answers to those questions, the working plan has been designed around three main objectives:

1. IDENTIFY and CHARACTERIZE the accumulation of water vapor and secondary air pollutants in the western Mediterranean, and their interrelationships with episodes of atmospheric secondary pollutants and the occurrence of convective and orographically aided summer storms (so-called colloquially "summer storms ").

2. ANALYZE the sensitivity of recharge processes (or feedback processes) of water vapor in the western Mediterranean basin to disturbances caused by climate change.

3. TRANSFER the results obtained implementing them into the surveillance and early warning systems on environmental (atmospheric) risks at the Valencian Community (extreme temperatures , heavy rains and secundary pollution episodes).

To optimize the configuration of meteorological meso-scale models run in the region to get better forecasts of topographycally-aided summer storms, VERSUS project follows two complementary approaches:

From a bottom-up approach, VERSUS aims to characterize the seasonal time-evolution of the evapotranspiration along the Turia Valley by means of measuring at different plots along the valley and by modelling the hydrological balance at the landscape scale and, coherently, upscaling to the whole basin scale. One of the main outcomes to be compared with the products obtained from the top-down approach is the apportionament of water vapor coming from the evapotranspiration under different meteorological conditions during the season of topographycally-aided summer-storm formation.

From a top-down approach, the numerical modelling tools run in the project will assimilate experimental data to reach realistic mixing ratio values along the Turia Valley and to appraise the land use as a key component to the reach the critical thershold for the topographycally-aided summer storm formation.

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VERSUS project is funded by the Spanish Ministry of Science and Technology, through the research project CGL2015-67466-R and co-funded by the European Regional Development Fund (ERDF), by the Conselleria de Cultura (Generalitat Valenciana, SPAIN) research project “DESESTRES”-- PROMETEOII/2014/038 and by the Generalitat Valenciana (Spain).