Drought and Flood in the Changjiang-Huaihe River Basin Associated with the Multi-Time-Scale Oscillation
江淮流域夏季旱涝与不同时间尺度大气扰动的关系

The drought and flood in the Changjiang-Huaihe River basin are studied from the riewpoint of multi-time-scale anomalous circulation. It is demonstrated that anomalous quasi-stationary wave influence is very important. The low frequency oscillation is also important and the influence of 10-20 days oscillation at 200 hPa and intraseasonal oscillation at 850 hPa is obvious. And the influence of synoptic scale system (3-10 days) is small compared to that of the low frequency oscillation and quasi-stationary wave. It is also found that the strength and position of southwest quasi-stationary flow in east Asia and northwestern Pacific area play an important role in the occurrence of drought and flood in the Changjiang-Huaihe River basin. If the southwest quasi-stationary flow is strong and has tendency to continent, there will be flood in the Changjiang-Huaihe River basin. If the southwest quasi-stationary flow is weak and has tendency to the ocean, there will be drought in the Changjiang-Huaihe River basin.