摘要
Two independent SST atlases have confirmed that there is a double seasonal signal in the surface layer of the northwestern Indian Ocean. The area enclosed by the 80F isotherm increases from January to a maximum in May followed by a decrease, a cool-down, to August, which has been explained recently. Then there is a second maximum of warm surface area in October/November, called a “second summer” for convenience. A hypothesis is proposed to explain this unusual second summer feature by extrapolating from available data. During July, August and September, the sea level slopes downward from the equator to the north providing a horizontal force to drive the warm surface water accumulated in the equatorial region back into the NW Indian Ocean basin. New observations are needed to check up on the hypothesis.
Two independent SST atlases have confirmed that there is a double seasonal signal in the surface layer of the northwestern Indian Ocean. The area enclosed by the 80F isotherm increases from January to a maximum in May followed by a decrease, a cool-down, to August, which has been explained recently. Then there is a second maximum of warm surface area in October/November, called a “second summer” for convenience. A hypothesis is proposed to explain this unusual second summer feature by extrapolating from available data. During July, August and September, the sea level slopes downward from the equator to the north providing a horizontal force to drive the warm surface water accumulated in the equatorial region back into the NW Indian Ocean basin. New observations are needed to check up on the hypothesis.
