1960-2016年秦岭—淮河地区热浪时空变化特征及其影响因素

基于134个气象站点1960-2016年逐日最高温和相对湿度数据,辅以趋势分析、空间分析和相关分析等方法,对秦岭—淮河地区热浪时空变化特征进行分析,探讨了赤道东太平洋海温异常与热浪变化的相关关系。结果表明：①近57年秦岭—淮河地区热浪呈现“非线性、非平稳和阶段性”的变化过程,年代变化可分为3个阶段：1960-1972年热浪呈现东西分异,分界线大致位于112°E,以东地区热浪异常偏多,以西地区则“高低交替”波动;1973-1993年热浪维持“低位波动”,并在20世纪80年代中期呈现快速增加;1994-2016年,关中平原、秦巴山区、巫山山区和四川盆地热浪维持“高位波动”,黄河下游、淮河平原和长江下游热浪则经历从“相对偏多”向“相对偏少”的转变;②在影响因素方面,最高温波动变化是秦岭—淮河地区热浪频次年代变化的主导因素,相对湿度变化的影响相对较弱;③近57年来关中平原热浪年代变化与赤道太平洋西部海温异常关系更为密切,长江流域与东部海温异常关系更为密切;对于黄河下游和秦巴山区的热浪变化与不同分区赤道太平洋海温异常关系均较弱。

Spatiotemporal variability of heat waves and influencing factors in the Qinling-Huaihe region, 1960-2016

In the context of global warming, the likelihood of concurrent heat waves is expected to increase in most parts of China, which will have social and environmental impacts. However, heat wave characteristics are likely to vary regionally. Based on maximum daily temperature and relative humidity data from 134 meteorological stations for the 1960-2016 period, the spatiotemporal variation in heat waves was investigated for the Qinling-Huaihe region. We also analyzed the relationship between El Ni?o-Southern Oscillation (ENSO) and heat waves. We found that the heat waves in the past 57 years in the study region can be characterized as non-smooth and non-linear. Three distinct phases of decadal change were identified. During the first phase (1960-1972), with 112°E as the dividing line, heat waves were highly variable with alternating highs and lows in the western part of the region, but occurred at high frequency in the eastern part. During the second phase (1973-1993), heat waves showed low-amplitude fluctuations across the entire region, and rapidly increased in the mid-1980s. The third phase (1994-2016) saw high-amplitude fluctuations in heat waves in the western part of the region, but heat waves decreased in the eastern part. Our results show that over the entire region, the extremes in heat have been more sensitive to daily maximum temperature than regional relative humidity changes. Thus, the cooling of daily maximum temperature along the Huai River led to a decreasing heat wave spatial extent. There was also a notable difference in the relationship between ENSO and heat waves in the Qinling-Huaihe region: a strong positive correlation in the north and a weak negative correlation in the south were observed. Particularly, heat waves on the Guanzhong Plain have been closely related to Ni?o 4, whereas the relationship has been weak along the lower reach of the Yangtze River. The Ni?o 1+2 and Ni?o 3 indices showed significant negative correlations with heat waves across the lower reach of the Yangtze River. In the lower reach of the Yellow River and Qinling-Daba Mountains, the variations in heat waves have been weakly correlated with equatorial Pacific sea surface temperature anomalies. In addition, there has been more close relationship between temperature anomalies of equatorial Western Pacific and decadal variation of heat waves on the Guanzhong Plain in recent decades, which has contributed to enhanced warming on the Guanzhong Plain and along the lower reach of the Yangtze River.