The Shallow Meridional Overturning Circulation in the Northern Indian Ocean and Its Interannual Variability

• Published in: Advances in atmospheric sciences Vol. 22; no. 2; pp. 220 - 229
• Main Author: 胡瑞金 刘秦玉 王启 J.StuartGODFREY 孟祥凤
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Nature B.V 01.03.2005; Physical Oceanography Laboratory & Ocean-Atmosphere Interaction and Climate Laboratory, Ocean University of China, Qingdao 266003%CSIRO, Division of Marine Research, GPO Box 1538, Hobart, Tasmania, Australia
• Subjects: Circulation; Ekman layer; Equator; Inflow; Interannual variability; Meridional overturning circulation; Ocean circulation; Ocean circulation models; Ocean currents; Ocean models; Oceans; Plankton; Surface wind; Variability; Water circulation; Wind stress; 倾覆循环; 北印度洋; 子午线; 年度变化; Indian Ocean; circulation index; meridional overturning circulation; northern Indian Ocean; interannual variability; wind stress
• ISSN: 0256-1530; 1861-9533
• DOI: 10.1007/bf02918511

The shallow meridional overturning circulation (upper 1000 m) in the northern Indian Ocean and its interannual variability are studied, based on a global ocean circulation model (MOM2) with an integration of 10 years (1987-1996). It is shown that the shallow meridional overturning circulation has a prominent seasonal reversal characteristic. In winter, the flow is northward in the upper layer and returns southward at great depth. In summer, the deep northward inflow upwells north of the equator and returns southward in the Ekman layer. In the annual meart, the northward inflow returns through two branches: one is a southward flow in the Ekman layer, the other is a flow that sinks near 10°N and returns southward between 500 m and 1000 m. There is significant interannual variability in the shallow meridional overturning circulation, with a stronger (weaker) one in 1989 (1991) and with a period of about four years. The interannual variability of the shallow meridional overturning circulation is intimately related to that of the surface wind stress. Several indices are proposed to describe the anomaly of this circulation associated with the cross-equatorial part.