Spatiotemporal changes of heat waves and extreme temperatures in the main cities of China from?1955 to?2014

摘要

In the past decades, severe heat waves have frequently occurred in many parts of the world. These conspicuous heat waves exerted terrible influences on human health, society, the economy, agriculture, the ecosystem and soon. Based on observed daily temperatures in China, an integrated index ofheat waves and extreme-temperature days was established involving thefrequency, duration, intensity and scale of these events across largecities in China. Heat waves and extreme-temperature days showed an increasingtrend in most regions except northwest China from?1955 to?2014. After the late?1980s, the increasing trend was more obvious than the decades before. The cities in the middle and lower reaches of the Yangtze River were threatened by the most serious heat events in the past 60?years, especially Chongqing and Changsha. Due to the subtropical monsoon climate and special terrain, Chongqing experienced the most heat events in a long period of time. Inparticular, there was obvious fluctuation of hot years in 31?cities, whichdid not continuously rise with global warming; 21?cities mainlylocated in the eastern and southern regions of China had an obvious risingtrend; eight?cities had a clear declining trend which was mainly distributed in thewestern and northern regions of China; and there were no extreme-temperature days in Kunming and Lhasa in the past 60?years. The study revealed an obvious differentiation of heat events for 31?cities under climate change; heat threat in most cities is increasing but declining or remaining unchanged in the other cities. The trend is likely to intensify with global warming.