中国东部气温极端特性及其气候特征

基于百分位等统计方法构建极端气候指数,分析中国东部气温极端特性变化的时空格局和趋势特征,探讨其与全球变暖和区域气候变率的关联性。结果表明,近60 a来,中国东部长期增暖趋势明显,高纬度北方地区和冬、春季节气温对全球变暖响应最为显著;相比于日最低气温,日最高气温上升趋势不明显,黄河与长江之间部分地区日最高温度出现下降趋势。全域日较差总体亦呈减小趋势;与日气温极值的平均状况和气候趋势相一致,极端低温事件强度下降趋势明显,黄河以北及东南沿海地区减弱显著。极端高温事件强度增加趋势并不明显,黄淮地区出现减小趋势;年霜冻日数和冰冻日数以及寒潮持续期的长期变化趋势以减少为主。高温热浪的持续期则以增加为主;中国东部极端气温事件频次与强度的演变格局存在同向一致性。极端低温影响指数的分布呈现北部大于南部、内陆大于沿海地区的特征,全域以一致性下降趋势为主,特别是东部沿海降低最为明显。另外,春季极端低温的影响指数大于冬季,且未有明显减小趋势。极端高温的影响指数增强趋势不明显,地区差异较大,指数的大值区影响增强的趋势显著。相比于强度,极端气温事件频次对全球气候变化的响应更为敏感。同时,副热带高压、南极涛动和北极涛动等区域性气候变率可能是调控中国东部极端气温事件形成和演化的重要因素。

The Climatic Variations of Temperature Extremes in the Eastern of China

Based on percentile and other statistical methods, the climate index was built to analyze the extreme peculiarities of temperature, its space-time evolution and the regional differences in the eastern China (ECM excluding Hongkong Macao and Taiwan), and the associations with the global and regional climatic and oceanic variabilities were discussed. The results show that, in the past 60 years, the long-term warming trend in the ECM is obvious. Due to the influence of latitude and seasons, the response to global warming is most obvious in the northern regions with high latitude and in winter and spring seasons. Compared with the daily minimum temperature, the daily maximum temperature did not distinctly increase especially in the central region between the Yellow River and the Yangtze River. As a result, the diurnal temperature range also showed a decreasing trend overall. In consistent with the average temperature extremes and climatic regioons, the intensity of extreme cold events (ECE) decreased significantly, especially in the north of the Yellow River and southeast coastal areas. However, the long-term trend of the intensity of extreme high temperature events (EHTE) is not obvious, especially in Huanghuai area where the decrease trend dominated. Long-term trends of annual frost and ice days and the cold wave duration experienced a reduce, while the heat wave duration gives priority to increase. The spatial pattern of the intensity and frequency of the extreme events were well consistency, and the response to global changes is remarkable. The impaction index of the ECE possessed greater values in northern region and inland, while lower in the southern regions and coastal areas. The corresponding long-term trend is decline with regional uniformity, especially in the eastern coastal areas. Meanwhile, the impaction index of the ECE in spring is higher than that in winter, and its decline trend is not obvious. The long-term increase trend of impact index of the EHTE was smaller and regional differences are significant. Moreover, the climatic trend in the areas with large values of impaction index was mainly enhanced, while that in the areas with smaller values most significantly weakened. Overall, the frequency of regional extreme temperature events is more sensitive to global climate change than the intensity. The analysis further shows that, the subtropical high, Antarctic and Arctic oscillations may be important factors influencing the formation and evolution of extreme temperature events in the EC.