Indian Ocean response to anomalous conditions in 2006

[1] The equatorial Indian Ocean (EIO) exhibited anomalous conditions characteristic of an Indian Ocean dipole (IOD) during 2006. The eastern EIO had cold sea surface temperature anomalies (SSTA), lower sea level, shallow thermocline and higher chlorophyll than normal. The anomalies in the east, restricted to the south of the equator, were highest off Sumatra. The western pole of the IOD was marked by warm SSTA and deeper thermocline with maxima on either side of the equator. An ocean general circulation model of the Indian Ocean forced by QuikSCAT winds reproduces the IOD of 2006 remarkably well. The switch over to cooling in the east and warming in the west happened during May and July respectively. In the east, airsea heat flux initiated cold SSTA in the model which were sustained later by oceanic processes. In the west, surface heat fluxes and horizontal advection caused warm SSTA and contribution by the latter decreased after August. Citation: Vinayachandran, P. N., J. Kurian, and C. P. Neema (2007), Indian Ocean response to anomalous conditions in 2006, Geophys. Res. Lett., 34, L15602, doi:10.1029/2007GL030194.

[1]  T. Yamagata.  The Indian Ocean dipole : a physical entity , 2002 .

[2]  S. Xie,et al.  Climate Fluctuations of Tropical Coupled Systems—The Role of Ocean Dynamics , 2006 .

[3]  P. N. Vinayachandran,et al.  Mechanisms of formation of the Arabian Sea mini warm pool in a high-resolution Ocean General Circulation Model , 2007 .

[4]  R. Reynolds,et al.  The NCEP/NCAR 40-Year Reanalysis Project , 1996, Renewable Energy.

[5]  James T. Potemra,et al.  Coupled dynamics over the Indian Ocean: spring initiation of the Zonal Mode , 2003 .

[6]  P. Vinayachandran,et al.  Indian Ocean dipole mode events in an ocean general circulation model , 2002 .

[7]  W. Large,et al.  Oceanic vertical mixing: a review and a model with a nonlocal boundary layer parameterization , 1994 .

[8]  Peter J. Webster,et al.  Coupled ocean–atmosphere dynamics in the Indian Ocean during 1997–98 , 1999, Nature.

[9]  P. Vinayachandran,et al.  Hydrographic observations and model simulation of the Bay of Bengal freshwater plume , 2007 .

[10]  G. Meyers,et al.  Interannual variability in the tropical Indian Ocean: a two-year time-scale of Indian Ocean Dipole , 2003 .

[11]  Jérôme Vialard,et al.  An OGCM Study for the TOGA Decade. Part II: Barrier-Layer Formation and Variability , 1998 .

[12]  N. Saji,et al.  Response of the equatorial Indian Ocean to an unusual wind event during 1994 , 1999 .

[13]  Toshio Yamagata,et al.  Possible impacts of Indian Ocean Dipole mode events on global climate , 2003 .

[14]  P. N. Vinayachandran,et al.  Extremes of the Indian summer monsoon rainfall, ENSO and equatorial Indian Ocean oscillation , 2004 .

[15]  Antonio J. Busalacchi,et al.  Oceanic processes associated with anomalous events in the Indian Ocean with relevance to 1997–1998 , 2000 .

[16]  Formation mechanisms of temperature inversions in the southeastern Arabian Sea , 2006 .

[17]  D. Antoine,et al.  Heating rate within the upper ocean in relation to its bio-optical state , 1994 .

[18]  K. Wyrtki,et al.  An Equatorial Jet in the Indian Ocean , 1973, Science.

[19]  L. Greischar,et al.  Atmospheric-hydrospheric mechanisms of climate anomalies in the western equatorial Indian Ocean , 1993 .

[20]  Y. Masumoto,et al.  Interannual subsurface variability in the tropical Indian Ocean with a special emphasis on the Indian Ocean Dipole , 2002 .

[21]  B. Goswami,et al.  A dipole mode in the tropical Indian Ocean , 1999, Nature.