Study On Sea Temperature Of The Tropical Indian Ocean

Based on monthly average Argo data from January 2004 to August 2008, weekly average Argo data from January 2003 to December 2008,NCEP monthly surface wind data and daily OLR data, by using the research methods such as average analysis, standard deviation analysis, correlation analysis, power spectrum analysis and wavelet analysis, the spatial distribution of sea temperature and the significant periods of it and the mechanism of the significant periods in tropical Indian Ocean are studied.It is showed that in the surface,Arabian Sea, Bay of Bengal and the equatorial eastern Indian Ocean are not only warm center but also low-value center of standard deviation.Overall,the sea temperature anomaly of sea surface temperature in areas with high sea temperature is small, and the two distribution patterns consistently.In the subsurface and deeper layers,the southwest tropical Indian Ocean is warm.On the contrary, East-west equatorial Indian Ocean is cold.Compared with surface and deeper layers, subsurface has the biggest sea temperature anomaly in the tropical Indian ocean. In tropical Indian Ocean, the sea temperature of the surface and subsurface layers alters obviously during season changing, while the highest sea temperature occurs in the spring. Arabian Sea and the eastern tropical Indian Ocean have larger seasonal variation of sea temperature than the others. Because these two sea area are the marine information area of tropical Indian Ocean, and both of them locate in the strong center of air-sea interaction. Arabian Sea and the Bay of Bengal are at the same latitude, and their sea surface temperature changes in the basic synchronization, but in the subsurface Arabian Sea temperature changes ahead that of the Bay of Bengal about 2-4 months. The east and west dipole regions are also on the same latitude. In the surface, SST of west dipole region changes ahead of that of the east dipole region 1 month; But in the subsurface, their sea temperature changes simultaneously. Sea temperature has significant periods such as year period, half-year period, and inseasonal period in tropical Indian Ocean. In different areas and depths there are different significant periods. The sea temperature intraseasonal oscillation are widespread in tropical Indian Ocean, and sea temperature intraseasonal oscillation signal can reach deep layers. The spatial distribution of sea temperature intraseasonal oscillation is uneven. Such as on the equator, intraseasonal oscillation signal spreads both eastward and westward. Outside the equator, the intraseasonal oscillation signal spreads westward more obviously, but the propagation speed are different in different area, and the intraseasonal oscillation signal also has interannual variations. The sea temperature on thermocline layer and mixed layer has obvious seasonal variation and intraseasonal oscillations in tropical Indian Ocean. The intensity of the seasonal oscillation signal in thermocline layer and mixed layer are the different. The sea temperature anomalies of surface and subsurface are formed of the interaction between atmosphere and ocean. In the surface, the one-year significant period of sea temperature is effected by the solar radiation, and in the subsurface, the one-year significant period is effected by ocean currents, Rossby waves and coastal Kelvin waves. The half-one-year significant period of SST is related with Moonsoon, while in the subsurface the period is related with Moonsoon and Wyrtki Jet. The intraseasonal oscillation maybe produced by fluctuations in atmospheric forcing and ocean combined effect of the internal results in the tropical Indian Ocean. Both sea surface wind and La Nina are the causes of the different positive dipole intensity of 2006 and 2007.