Evaluation of heat waves events on Shandong peninsula (1961-2014): study about the climatological evolution using Excess Heat Factor indices (EHF)​

Eastern China has been facing an increasing number of heat wave events in recent decades, which can have serious repercussions on human health and the economic system. Thirty timeseries of daily maximum and minimum temperature for the period 1961-2014 were analyzed and used to determine Excess Heat Factor (EHF) index in order to evaluate the climatology and trends of heat wave events in the Shandong Peninsula. Through EHF it is possible assess six different aspects linked to heatwaves: the hottest day of the hottest yearly event (HWA), length of the longest event of the year (HWD), annual sum of days participating to heat waves (HWF), average magnitude of the yearly events (HWM), average number of all annual events (HWN) and number of days which determine a severe heat wave event (HWsev). The severity threshold was set for each station using the 85th percentile of the empirical distribution of positive EHF values. Generally during 1961-2014 Shandong peninsula did not experience particularly powerful events. The eastern area displayed more long and frequent events, whereas the western part showed more intense events. The study of trends of the peninsula allow to underline an exacerbation of all aspect (a part of HWM) during nineties, probably due to the intense urbanization of the territory which caused a synergic interaction between urban heat island (UHI) and heat wave events. However, weather stations trends were found positive and statistically relevant for all aspect all over the peninsula. Considering the HWM aspect, not all stations showed statistically relevant upward trends (almost 40% of stations did not). Finally, HWsev was assessed for the principal cities and there was found that Qingdao experienced the most severe event in 2002.