The Temporal And Spatial Variation Of The Sea Temperature Over The Region Of The Somalia Current System

Based on Argo temperature data and SODA data, the structure and variations on differenttime scales of the sea temperature above400m in the Somalia current region are studied. It isshowed that the isotherms of annual mean SST (sea surface temperature) parallel to thecoastline and temperature in the east is warmer than the west. Around the thermocline, thestructure of the warm and cold temperature centers are clear and all concentrated in thecoastal regions. Under the thermocline, isotherm distributed latitudinally and the temperaturein the north is higher than the south. The cold centers in9°N and4°N,warm center in6°N-8°N obviously exist in the upper400m. There is a low value of standard deviation zone inequator of upper water. And standard deviation of maximum value is near the cold center.Near thermocline, maximum value is in high temperature gradient. Temperature center hasminimum value. The standard deviation The standard deviation center and temperature centerare approximately complementarily distributed.On the seasonal time scale, the semi-annual periodic signal of SST is obvious, withwarmer in spring and autumn while colder in winter and summer. Especially in summer, theSST is the lowest and structure characteristic is the most complex. The standard deviation isthe highest in autumn and lowest in winter. The semi-annual signal becomes weaker as depthincreases and the center distribution is also different. The warm center at6°N is strong insummer and disappears in winter. The cold center at4°N is strongest in winter. The maximumof temperature standard deviation comes in summer, and minimum comes in spring. Belowthe thermocline, the maximum of temperature standard deviation comes in autumn, and it ismuch more different from temperature. The warm center at6°N-8°N is significantly existed inMay and November, cold center at4°N only exist in August. The cold center at9°N is strongin each moth especially in May and August. Seasonal variation is clearly different from eachcenter, they interrelate closely in upper water in particular at the same time.For the interannual variability，it is found that the temperature changes consistent inspring, autumn and winter. But, there are two patterns of SST variability in August. One is inphase over the whole region, the other is out of phase between the north and south region of the Somalia current. ENSO,IOD index and IMI impact this two pattern of Somali SSTtogether. The temperature changes in region of the Somalia current will affect the lower waterespecially in5°S-10°S of the southwest Indian Ocean. And this kind of influence propagateseastward in a few months. Composite analysis shows that for the in phase pattern, the signalsof wind stresses are obvious in the Somali coast, the southwest of the tropical Indian Oceanand the Arabian Sea in June. This represents that upwelling and evaporate impact on the SST.While for the opposite pattern, it’s different from the in phase pattern, the signals are obviousin May and the size also the location are not correspond. Besides, SST anomaly in the northregion cannot be interpreted as upwelling and evaporate.The period of intraseasonal signal is25d-137d of the temperature in the region of theSomalia current, but each significant period has its own characteristics.