Seasonal Variation of the Seychelles Dome

Abstract Using an ocean general circulation model (OGCM), seasonal variation of the Seychelles Dome (SD) is investigated for the first time. The SD is an oceanic thermal dome located in the southwestern Indian Ocean, and its influence on sea surface temperature is known to play an important role in the Indian monsoon system. Its seasonal variation is dominated by a remarkable semiannual cycle resulting from local Ekman upwelling. This semiannual nature is explained by different contributions of the following two components of the Ekman pumping: one term that is proportional to the planetary beta and the zonal wind stress and the other term that is proportional to the wind stress curl. The former is determined by the seasonal change in the zonal component of the wind stress vector above the SD; it is associated with the Indian monsoon and causes downwelling (upwelling) during boreal summer (boreal winter). The latter, whose major contribution comes from the meridional gradient of the zonal wind stress, als...

[1]  S. Levitus.  A comparison of the annual cycle of two sea surface temperature climatologies of the World Ocean , 1987 .

[2]  Elizabeth C. Kent,et al.  The Southampton Oceanography Centre (SOC) Ocean - Atmosphere, Heat, Momentum and Freshwater Flux Atlas , 1998 .

[3]  Kozo H. Yoshida.  A Theory of the Cromwell Current (the Equatorial Undercurrent) and of the Equatorial Upwelling , 1959 .

[4]  S. Behera,et al.  Subsurface influence on SST in the tropical Indian Ocean: structure and interannual variability , 2005 .

[5]  Thomas M. Smith,et al.  Improved Global Sea Surface Temperature Analyses Using Optimum Interpolation , 1994 .

[6]  Y. Masumoto,et al.  Simulated Multiscale Variations in the Western Tropical Pacific: The Mindanao Dome Revisited , 2002 .

[7]  Shoichi Kizu,et al.  Japanese Ocean Flux Data Sets with Use of Remote Sensing Observations (J-OFURO) , 1999 .

[8]  Timothy P. Boyer,et al.  World ocean atlas 2001 : objective analyses, data statistics, and figures : CD-ROM documentation , 2002 .

[9]  Ngar-Cheung Lau,et al.  Remote Sea Surface Temperature Variations during ENSO: Evidence for a Tropical Atmospheric Bridge , 1999 .

[10]  F. Schott,et al.  The monsoon circulation of the Indian Ocean , 2001 .

[11]  James W. Hurrell,et al.  Twentieth century north atlantic climate change. Part I: assessing determinism , 2004 .

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

[13]  James A. Carton,et al.  A Simple Ocean Data Assimilation Analysis of the Global Upper Ocean 1950–95. Part I: Methodology , 2000 .

[14]  Dimitris Menemenlis,et al.  Effects of the Indonesian Throughflow on the Pacific and Indian Oceans , 2002 .

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

[16]  J. S. Godfrey.  On Ocean Spindown I: A Linear Experiment , 1975 .

[17]  J. McCreary,et al.  A Model of Tropical Ocean-Atmosphere Interaction , 1983 .

[18]  Ping Liu,et al.  Southwest Indian Ocean SST variability : Its local effect and remote influence on Asian monsoons , 2005 .

[19]  T. Jensen.  Equatorial variability and resonance in a wind-driven Indian Ocean model , 1993 .

[20]  J. S. Godfrey.  The effect of the Indonesian throughflow on ocean circulation and heat exchange with the atmosphere: A review , 1996 .

[21]  J. S. Godfrey,et al.  The role of Indonesian throughflow in a global ocean GCM , 1993 .

[22]  J. Smagorinsky,et al.  GENERAL CIRCULATION EXPERIMENTS WITH THE PRIMITIVE EQUATIONS , 1963 .

[23]  T. Yamagata,et al.  Response of the Eastern Tropical Pacific to Meridional Migration of the ITCZ: The Generation of the Costa Rica Dome , 1991 .

[24]  R. Pacanowski,et al.  Parameterization of Vertical Mixing in Numerical Models of Tropical Oceans , 1981 .

[25]  M. Cane,et al.  A Note on Low-Frequency Equatorial Basin Modes , 1981 .

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

[27]  Y. Masumoto,et al.  Response of the Western Tropical Pacific to the Asian Winter Monsoon: The Generation of the Mindanao Dome , 1991 .

[28]  A. Gordon,et al.  Spreading of the Indonesian Throughflow in the Indian Ocean , 2004 .

[29]  A. Mariano,et al.  Dynamics of the Eastern Surface Jets in the Equatorial Indian Ocean , 1999 .

[30]  P. Vinayachandran,et al.  Monsoon Response of the Sea around Sri Lanka: Generation of Thermal Domes and Anticyclonic Vortices , 1998 .

[31]  Swadhin K. Behera,et al.  The Role of the Western Arabian Sea Upwelling in Indian Monsoon Rainfall Variability , 2008 .

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

[33]  A. Navarra,et al.  Interannual-to-decadal variability of the North Atlantic from an ocean data assimilation system , 2004 .

[34]  S. Xie,et al.  Structure and Mechanisms of South Indian Ocean Climate Variability , 2002 .

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

[36]  T. Yamagata,et al.  Coupled Ocean‐Atmosphere Variability in the Tropical Indian Ocean , 2013 .

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