Long description

This chart shows major flows and water masses.

The horizontal axis is unlabelled but is marked in units of degrees latitude, from 80 degrees south (Antarctic) to 80 degrees north (Arctic), at intervals of 20 degrees, with the Equator marked at zero degrees.

The vertical axis is labelled 'depth' and is marked in units of metres, from zero to 6000, at intervals of 1000 metres beginning at the top.

The water masses and flows are complex, but two main water masses are labelled:

1. The AABW. The upper boundary of this mass descends fairly steadily from around 500 metres depth at 75 degrees south to around 4500 metres depth at the Equator. Its lower boundary descends sharply to around 5200 metres at 60 degrees south then fluctuates between approximately 4500 and 5800 metres, linking with the upper boundary at the Equator. Within the AABW, the main flow follows the lower boundary from the Antarctic to the Equator with a rising branch at around 50 degrees south creating a vertical circulation.
2. The NADW. The upper boundary fluctuates between 2000 metres depth at 50 degrees south, reaching the surface at approximately 60 degrees north. This lower boundary descends evenly to 5800 metres at 30 degrees north, then ascends to 1500 metres in the Arctic. Within the NADW, the main flows are southwards at various depths, with some northward flow at depth between the Equator and 30 degrees north.