Annual variation of heat transport in the Pacific and Indian Oceans

Abstract

An important element in the maintenance of the Earth's climate is the redistribution of heat from surplus to deficit regions. Previous estimates^1–5 have shown that the oceanic heat transport is comparable to that of the atmosphere especially in the tropics and sub-tropics and that the ocean shows a similar seasonal transport carrying energy into the winter hemisphere. The annual mean meridional heat transport in individual oceans has also been estimated^6–8. Heat storage can be computed from subsurface data to provide a picture of the annual cycle of the heat transport for each ocean separately. Lamb^9,10presented such estimates for the Atlantic Ocean and found a southward heat transport in the November–December season with a northward heat transport in both hemispheres at other seasons. A similar method is used here to compute the seasonal variation of the heat transport north of 20°S for both the Pacific and the Indian oceans. The Pacific Ocean exhibits two regimes. North of 20° N transport is mostly northward with a maximum in September. Transport between 20°N and 20° S is evenly divided between northward (with a March maximum at 10° N) and southward (with an August maximum at 10°S). In the Indian Ocean, the transport is mostly southward except during January–February when a small northward transport appears north of 5°S.