全球变暖背景下长江三角洲夏季高温时空演变研究

基于国家气候中心提供的2000站逐日地面气温资料，运用高温日数、平均高温度数以及日最高气温这3个指标刻画1961~2015年长江三角洲（简称长三角）地区的夏季高温时空演变，并在对上述指标进行突变检测的基础上，比较其转折前后的夏季高温空间分布特征。结果表明：（1）长三角夏季高温指标在2000年左右存在气候突变，2000年以后夏季高温日数和强度出现显著上升；（2）较之2000年前，2000年后的高温度日数的分布型更为集中，前三个EOF模态解释方差均有所上升，EOF1分布较为相似，EOF2不再呈现带状分布，EOF3局地性特征减弱；（3）2000年后的长三角夏季高温日数增长明显，年平均高温日数达到20 d以上的区域向北扩展至32°N附近，向东扩展至往浙江东部沿海；年平均高温日数达到30 d以上的区域更扩展至31°N以南、121°E以西所有地区，高温日数最多可达近50 d；（4）2000年后高温度日数呈明显增加，从2000年前的10~20℃·d增加到20~50℃·d，以30~31°N一带增长最为显著。浙江中部和南部地区在2000年后高温日数增长明显，但高温强度增长较弱；安徽东部、浙江北部和上海地区高温日数和强度均增长明显。

Spatial and Temporal Characteristics of Summertime High Temperature in Yangtze River Delta under the Background of Global Warming

Based on the daily surface temperature data from National Climate Center of China, three summertime high temperature (SHT) indices: SHT days, SHT intensity and daily maximum temperature are defined to depict the summertime high temperature (SHT) in Yangtze River Delta (YRD) from different perspectives. On this basis, the mutations of the SHT and the before and after comparison of the spatial and temporal characteristics of SHT are detected over the period 1961-2015. The result shows that there exits an abrupt mutation in SHT around 2000. As compared to the SHT before 2000, more SHT days and higher SHT intensity are found after 2000. The analysis of Empirical Orthogonal Function (EOF) shows that the explained variances of the first three modes have an increase, indicating a more concentrate SHT distribution. Compared with the first three modes before 2000, a similar distribution of EOF1, a non zonal distribution for EOF2 and a weak locality distribution for EOF3 are found after 2000. The areas with SHT are enlarged after 2000. The areas with SHT exceeding 20 days have a northward expansion to around 32°N and an eastward expansion to the coast of Zhejiang province. Moreover, the areas with SHT exceeding 30 days cover the whole region to the south of 32°N and west of 121°E, and the maximum SHT days is up to almost 50 days. The SHT days have an apparent increase from 10~20℃·d before 2000 to 20~50℃·d after 2000, which is most significant around 30~31°N. After 2000, it has an evident increase for SHT days and comparatively weak increase for SHT intensity in middle and south of Zhejiang province, and both evident increase for SHT days and intensity in east Anhui, north Zhejiang, and Shanghai.