Abstract: The modulation of Madden-Julian oscillation (MJO) on the precipitation of Southeast China and the possible teleconnections are investigated. The composites station precipitation data show that it has significant response to MJO: during the first four phases of MJO the precipitation rate is anomaly high, while the last four phases the precipitation rate is anomaly low. The diagnosis of the mositure budget shows that it is the anomaly meridional wind that transports the anomaly mositure from the tropical area to Southeast China. The composites of anomaly geopotential height and wind at 500 hPa show that the MJO can excite the PNA teleconnection, which accompanies the anomoly meridional wind. The EOF analysis of v in related region shows an MJO related mode: the spatial pattern of EOF1 lags EOF2 for a quarter, while the time series PC1 leads PC2 for a quarter. This MJO related mode may explain the meridional wind and the consequence precipitation modulation to Southeast China.

Key words: MJO, precipitation anomalies, moisture budget, meridional wind anomalies

摘要： 研究Madden-Julian 振荡(MJO)对于中国东南部地区冬季降水的调制, 分析了可能的遥相关机制。通过对中国气象局发布的站点观测降水资料的合成分析, 发现MJO 对于中国东南部冬季降水有显著的影响: 在MJO的前4个相位, 降水存在正异常(湿); 在MJO的后4个相位, 降水存在负异常(干) 。对水汽收支的诊断结果表明, 经向风异常造成的水汽通量异常, 是造成降水正负异常的主要原因。通过对500 hPa位势高度异常场和风场的分析, 以及对经向风异常 EOF 分析表明, MJO 通过激发PNA 型而影响到经向风场, 异常风场具有和 MJO 相关的变化模态, 即: EOF1落后EOF2 1/4 周期, PC1 领先 PC2 1/4 周期。这种径向风的异常最终导致了中国东南部地区冬季降水的异常。

关键词: MJO, 降水异常, 水汽收支, 经向风异常