过去530年中国东部旱涝事件模拟研究初探

A MODELING STUDY ON DROUGHT AND FLOOD EVENTS OF THE LAST 530 YEARS IN EAST CHINA

利用CCSM2.0.1模式完成的千年模拟试验结果对近530年中国东部区域旱涝事件进行了初步的研究。结果表明模式一定程度能够反映过去530年中国东部降水变化规律,在年代际变化上与旱涝等级资料较为一致。模式能模拟出旱涝事件世纪尺度变化特征以及旱涝事件的群发现象。从模拟结果中发现,过去530年中国东部共发生了3次持续时间5年或5年以上的严重干旱事件,分别发生在1483～1488年、1635～1645年和1964～1968年;4次持续时间5年或5年以上的严重洪涝事件,分别发生在1529～1533年、1749～1753年、1926～1932年和1978～1984年。其中,1483～1488年、1635～1645年和1964～1968年干旱事件以及1749～1753年洪涝事件与旱涝等级序列有较好的对应,说明模式对严重干旱事件具有一定的再现能力,而对严重洪涝事件的模拟能力还有待加强。对个例分析发现,对应较好的3次严重干旱事件发生时期降水空间型态的演化与1749～1753年严重洪涝事件不同,前者前期呈南涝北旱格局,旱区逐年向东、南扩大,后者前期同样也呈南涝北旱格局,但为涝区逐年向东、北扩大。模拟还发现中国东部夏季降水的异常变化主要受夏季风影响,发生严重干旱事件期间夏季风偏弱,发生严重洪涝事件期间夏季风偏强,模拟显示严重旱涝事件期间副热带高压无明显变化。

Severe drought and flood events of the last 530 years in East China were investigated by a 1000-yr global climate model CCSM2.0. 1. The simulated summer precipitation and drought and flood events are, on an interdecadal scale,consistent with the historical records. There were three severe drought events lasting 5 years and more occurred in 1483 - 1488, 1635 - 1645 and 1964 - 1968 and four severe flood events lasting 5 years or more occurred in 1529 - 1533, 1749 - 1753, 1926 - 1932 and 1978 - 1984. Especially,the three drought events and the 1749 - 1753 flood event are very clear and definite in the historical records. As to the three drought events,they first developed in North China and then expanded southward to the middle and lower reaches of the Yangtze River, while as to the 1749 - 1753 flood event,it first developed in the middle and lower reaches of the Yangtze River and then expanded northward to North China. It is found that such lasting drought and flood events can be attributed to influence of summer monsoon,whereas the Western Pacific subtropical high pressure plays only a minor role.