基于ENSO发展过程的中国夏季降水时空变化特征

利用1961—2019年中国地面降水月值格点数据,结合趋势分析、合成分析及T检验等气候诊断方法,对中国夏季降水时空变化特征进行分析,进而探讨不同类型ENSO事件对应夏季降水规律。结果表明：20世纪60—90年代末,长江、淮河夏季降水波动增加,海河降水持续下降,符合“南涝北旱”空间特征;21世纪后,除淮河夏季降水下降之外,其他流域降水均呈增加趋势;对于不同ENSO发展类型而言,以厄尔尼诺为主导的事件,副高脊线西伸增强,中国夏季多雨区集中在江淮地区,由南向北呈现“中间涝,南北旱”的空间格局;以拉尼娜为主导的事件中,副高脊线东移、控制面积缩小,中国夏季降水在胡焕庸线两侧、华南降水明显偏少;对于两种转换型事件而言,当前冬发生厄尔尼诺、夏季转为拉尼娜时,副高西伸且面积扩大,中国夏季降水偏多;反之,副高东移且面积缩小,中国夏季降水整体偏少。

Spatio-temporal variation of summer precipitation in China based on ENSO development process

Continuous global warming will bring more extreme precipitation events. Summer precipitation in China has obvious chronological changes, which is closely related to El Niño-Southern Oscillation. Thus, based on the gridded dataset of monthly precipitation with a spatial resolution of 0.5°×0.5° during 1961-2019, this paper analyzes the spatio-temporal variation of summer precipitation in the nine major basins of China using the trend analysis, t-test, and synthetic analysis. Based on seven ENSO events, the summer precipitation patterns were discussed. Results are shown as follows. (1) The summer precipitation increased significantly (p<0.05) in inland river basins such as Hexi Corridor, areas north and south of the Tianshan Mountains, and areas west of the Qinghai-Tibet Plateau, Southeast River drainage basins and the middle and lower reaches of the Yangtze River, while precipitation in both Haihe River Basin and Songliao River Basin decreased significantly during the period 1961-2019. (2) From the 1960s to the late 1990s, the precipitation fluctuations in the Yangtze and Huaihe River Basins increased, while that in the Haihe River Basin continued to decline, which was in line with the spatial characteristics of "Southern Floods and Northern Droughts". After 2000, except in the Huaihe River, and the summer precipitation in other river basins showed an increasing trend. (3) In the events dominated by El Niño, the ridge line of the Western Pacific Subtropical High (WPSH) extended westward, and the summer precipitation areas were concentrated in the Jianghuai area, showing a spatial pattern of three-pole-type from south to north, with more precipitation in Jianghuai Basin and less precipitation in the north of China and the Pearl River Basin in summer. In the events dominated by La Nina, the ridge line of the WPSH moved eastward and the control area narrowed. The summer precipitation obviously decreased on both sides of the "Hu Huanyong Line" and in South China. As for the two conversion ENSO events, when El Niño occurs in winter and La Nina changes in summer, the WPSH extends westward and its area expands, and there is more summer precipitation in China. On the contrary, the WPSH moves eastward and its area shrinks, resulting in less summer precipitation. This study highlighted that the spatio-temporal differentiation of ENSO events in the previous winter and summer, and analyses the abnormal laws of summer precipitation in the nine major basins in China, which has an important theoretical and practical significance to taking effective measures in regional flood prevention.