DATE2022-04-28 10:12:22
TITLELong term climatology and trend of heatwaves over Greece from 1950 to 2020
AUTHORSE. Galanaki (1) ,Ch. Giannaros (1) ,G. Papavasileiou (1) ,V. Kotroni (1) ,K. Lagouvardos (1)
  1. 1) National Observatory Of Athens, Athens (Greece)
ABSTRACTExtreme temperatures are of major concern in the scientific community as they directly affect the natural and human environment. Many studies have shown that the average global temperature is rising at a rate of 0.18 °C per decade, while the frequency, intensity, and geographic extent of heat waves are expected to increase in the future. In Greece in particular, it is estimated that the season of hot extremes will increase by about 1 month in the near future (2021 – 2050) and by 2 or more months up to 2100, resulting to prolonged periods of thermal stress, which can lead to heat-related illnesses and premature deaths. Thus, the need to study heat waves and their characteristics becomes imperative. The current work, which is funded by the European Climate Foundation, focuses on the study of the long-term variability and trends of various characteristics of heatwaves at country-scale in Greece. The analysis covers the period 1950-2020 and it is based on the global reanalysis data set ERA5-Land, provided by the European Center for Medium-Range Weather Forecasts at the high spatial resolution of 0.1O × 0.1O (~ 9km). The heatwaves were determined using two different exceedance criteria according to the following indices: (a) the 95th percentile of the maximum daily temperature, and (b) a modified version of the Excess Heat Factor index, based on the 90th percentile of the apparent temperature. A heatwave was defined when both criteria were met for at least three consecutive days. The investigation of the heatwaves spatiotemporal characteristics was conducted using several indices, including the intensity, frequency, number and duration of heatwaves and the peak temperature and heat stress hours during the heatwaves. Results showed that Greece experienced an average of approximately 50 heatwaves during the examined period, while the heatwave occurrence presents an increased trend after the 1990s, in agreement with previous studies. Overall, Greece experiences 0.8 heatwaves per summer, with each of them lasting about 5 days on average. The analysis demonstrates a strong increasing tendency in almost all the applied heatwaves indices during the examined period.