Drought and Flood in the Changjiang-Huaihe River Basin Associated with the Multi-Time-Scale Oscillation
Li Guilong and Li Chongyin (State Key Laboratory of Numerical Modeling for Atmosphere Science and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing100080)
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.