关键词: 降雨特征;气候成因;典型涝年;水汽输送;长江上游;

Abstract: To analyze the rainfall characteristics and climatic causes of typical flood years during the main flood season in the upper reaches of the Changjiang River from a more detailed perspective, this study divided the upper reaches of the Changjiang River into five key areas.Then using the daily rainfall data from 282 rainfall stations in the upper reaches of the Changjiang River from 1961 to 2021,we analyzed the rainfall characteristics of the main flood season in the upper reaches of the Changjiang River and the five key areas by Morlet wavelet analysis, and classified the typical flooding years.Finally we explored the water vapor transport and the climatic causes of the typical flooding years with different types of rainfall.The results showed that:(1) The interannual fluctuations of rainfall in the upper reaches of the Changjiang River, Jinsha River and the upper main stream of the Changjiang River were consistent on the whole, and the occurrence time of abnormal wet years was consistent.The rainfall cycles in the upper reaches of the Changjiang River and the five key regions were consistent, with a three-year oscillation cycle.(2) The rainfall in the five key areas of the upper reaches of the Changjiang River in typical wet years could be divided into three categories: uniform polytype in the key area, four-over-one-under type in the key area, and three-over-two-under type in the key area.(3) There were differences in the water vapor transport sources of different rainfall types in the upper reaches of the Changjiang River during the main flood season.The water vapor transport of uniform polytype and four-over-one-under type in the key area were mainly from the Western Pacific and the Bay of Bengal, while the water vapor transport of three-over-two-under type in the key area was mainly from the Western Pacific and the South China Sea.(4) More snow cover on the Qinghai-Tibet Plateau is conducive to more precipitation in the upper reaches of the Changjiang River.The uniform polytype in the key area generally occurred in the years when the warm sea temperature changed to the cold sea temperature.The four-over-one-under type and three-over-two-under type in the key area generally occurred in the years when the winter sea temperature was cold.

Key words: rainfall characteristics; climatic causes; typical flooding years; water vapor transport; upper reaches of Changjiang River;