CR 79:63-75 (2019)  -  DOI: https://doi.org/10.3354/cr01578

ABSTRACT: Summer heat wave (HW) events have disastrous consequences for human health, economies, and ecosystems. The present study investigates the variability of HWs and estimates the recurrence probabilities of the severe 2003 and 2013 hot summers in Zhejiang Province, southeast China. We define a HW event as ≥3 consecutive days having a daily maximum temperature ≥35°C. Considering this definition, 2 HW indices were adopted: the yearly sum of accumulated harmful high temperature (YAHHT) of HWs and the yearly sum of HW duration (HWD). We found that the YAHHT and HWD have had significant increasing trends in the majority of Zhejiang. The inter-annual variability of HWs can be divided into 3 periods: 1973-1987, 1988-2002, and 2003-2017. The severity levels of HWs in Zhejiang had a clearly increasing trend according to the YAHHT and HWD. The average YAHHT and HWD in 2003-2017 were, respectively, >2.0 and >1.5 times those in 1973-1987 and 1988-2002. We also estimated the recurrence probabilities of the HWs that occurred in Zhejiang during July-September 2003 and 2013. The recurrence probabilities of such severe HWs, which were assessed in simulations using an information diffusion model, are higher in the present climate.

KEY WORDS: Variability · Recurrence probability · Accumulated harmful high temperature of heat waves · Information diffusion model