Intra-annual variability of the Western Mediterranean Oscillation (WeMO) and occurrence of extreme torrential precipitation in Catalonia (NE Iberia)

摘要: Abstract. In previous studies the Western Mediterranean Oscillation index (WeMOi) at daily resolution has proven to constitute an effective tool for analysing the occurrence of episodes torrential precipitation over eastern Spain. The western region is a very sensitive area, since climate change can enhance these weather extremes. present study we created catalogue extreme ( ≥200  mm in 24 h) that took place Catalonia (NE Iberia) during 1951–2016 study period (66 years). We computed daily WeMOi values and constructed WeMOi calendars. Our principal result reveals 50 (0.8 cases per year), mainly concentrated autumn. confirmed threshold WeMOi  ≤ −2 define negative WeMO phase at resolution. Most 50 episodes (60 %) area occurred on days presenting value. Specifically, most are detected autumn, from 11 20 October, coinciding with highest frequency events. On comparing subperiods, we observed statistically significant decrease all months, particularly late October November December. No changes were between both subperiods. contrast, displacement early autumn; this be related warming sea temperature.