This study details the contribution of different Mediterranean cyclone types (obtained using a potential-vorticity based classification) to the Mediterranean hydrological cycle. The approach allows attributing trends in evaporation E, precipitation P and the net freshwater flux (E-P) to the different frequency and intensity changes of each cyclone category. Of particular interest is the finding that the impact of Mediterranean cyclones on P, E, and E-P substantially varies according to the cyclone type. Therefore, understanding trends in the hydrological cycle in the Mediterranean must go beyond counting cyclones and also look at cyclone types and their specific frequency trends.

This study utilised the ECMWF Integrated Forecasting System over an impressively long evaluation period of more than three years to document the impact of assimilating Aeolus wind observations on predictions of wind and precipitation globally. This long-term perspective provides a level of statistical confidence often missing from shorter-term campaign evaluations. Another key aspect of this NWP-oriented study is the consideration of the improvement of precipitation forecasts in different seasons – it is largest during the cold season in the extratropics – with some explanations why effects differ across hemispheres and seasons.