Weather types and rainfall microstructure in Leon, Spain

Lamb's weather types classification has been used here to analyse the characteristics of raindrops in relation with the meteorological situation. A rainfall gathering campaign has been carried out in Leon [northwesterly (NW) Spain] over 34 months. An optical disdrometer has been used to determine drop sizes and the meteorological situations have been classified from the pressure values at surface level in 16 grid points over the study zone. The results have revealed seasonal differences in the average duration of the rain events: 40min in winter and 12 in summer. In the study period, the rainiest weather types were the cyclonic types, and the air flows from the north and the west. The raindrop sizes follow a gamma distribution with a higher mode in the case of the weather types with air masses from the west and the southwest. The only exception lies in the purely directional weather types, where a higher mode is found in the case of rain events with eastern flows.