DATE2022-07-13 12:48:02
TITLECombined climate extremes occurrences driven by multi-scale atmospheric variability and their impacts on Mediterranean metropolitan cities
AUTHORSIliana Polychroni (1) ,Maria Hatzaki (1) ,Panagiotis T. Nastos (1) ,Michalis Toumpos (2) ,John Kouroutzoglou (2,3) ,Helena A. Flocas (2)
  1. 1) Laboratory Of Climatology & Atmospheric Environment, National And Kapodistrian University Of Athens, Athens (Greece) ,2) Section Of Atmospheric Physics - Meteorology, National And Kapodistrian University Of Athens, Athens (Greece) ,3) Hellenic National Meteorological Service, Hellinikon, Athens (Greece)
ABSTRACTMetropolitan areas with different climatic and topographic characteristics are increasingly impacted by weather and climate extreme events putting at risk their populations. Thus, the frequency and the multidecadal variability of combined climate extreme occurrences on selected highly populated Mediterranean cities are investigated, along with their association with the atmospheric variability on different spatiotemporal scales. Specifically, four combined extreme indices that reflect joint modes of temperature and precipitation extremes, namely the co-occurrence of Cold/Dry (CD), Cold/Wet (CW), Warm/Dry (WD), and Warm/Wet (WW) days (Beniston, 2009; 2011), are analysed on seasonal basis for the period 1950-2021 with the high-resolution E-OBS gridded daily mean temperature and precipitation datasets (0.1°x0.1°) from the European Climate Assessment & Dataset (ECA&D, Klein Tank et al. 2002, The combined extreme occurrences are connected with the atmospheric variability of different scales, from large-scale teleconnection patterns to atmospheric blocking and synoptic activity, focusing as well on extreme seasons with exceptionally increased combined extreme occurrences. The analysis shows significant interdecadal and spatial differences of the combined extremes occurrences at the cities across the Mediterranean, connected with a non-uniform impact of the atmospheric variability. Specifically, NAO is not always and everywhere a dominant mode for the Mediterranean extreme occurrences, blocking position affects mainly the northwestern areas, while cyclonic activity is related to wet events, either cold or warm. The urban areas of western Africa are mostly affected by cold/dry events, while almost all urban areas around the Mediterranean experience high numbers of warm/dry events with increasing trends during the last decades. Acknowledgement: Cyclonic tracks data are based on work from COST Action CA19109 “MedCyclones”, supported by COST – European Cooperation in Science and Technology