印度洋海底压强的季节和长期变化

利用2003—2015年的重力恢复和气候实验(Gravity Recovery and Climate Experiment, GRACE)卫星观测数据, 揭示了印度洋海底压强的变化特征, 并探讨了其变化机制。结果表明, 印度洋海底压强具有显著的季节变化特征, 北半球冬季在40°S以北(南), 海底压强呈负(正)异常, 夏季分布与冬季相反。印度洋区域的海底压强空间分布与Ekman输送空间分布有较好的对应关系。正压涡度方程诊断结果表明, 利用风场重构的海底压强能够较好地解释印度洋海底压强的季节和长期变化。此外, 海平面变化收支分析表明, 海底压强的变化在高纬度区域主导了海平面变化。

Seasonal and long-term variability of ocean bottom pressure in the Indian Ocean

Using the GRACE satellite observation during 2003-2015, we reveal characteristics of the ocean bottom pressure (OBP) variability in the Indian Ocean, and explore their potential dynamics. The results show that the OBP in the Indian Ocean has significant seasonal variability. In the boreal winter, the OBP shows negative (positive) anomaly north (south) of 40 ^oS; and the pattern in summer is opposite to that in winter. The spatial pattern of the Ekman transport has a good correspondence with the OBP pattern in the Indian Ocean. The diagnosis results derived from the barotropic vorticity equation show that the OBP reconstructed by sea surface wind can better explain both the seasonal and long-term variations of the OBP in the Indian Ocean. In addition, analysis of sea level budget suggests that variation of OBP dominates sea level changes at high latitudes.