Interior Communication from the Subtropical to the Tropical Oceans*

The communication from the subtropical gyre interior to the Tropics is examined using wind stress datasets and results from an ocean data assimilation system. It is shown that the interior communication can be clarified by a simple interior mass communication rate (IMCR), which can be easily calculated from the Sverdrup function. For the Northern (Southern) Hemisphere the IMCR can be defined as the meridional minimum (maximum) of the Sverdrup function maximum (minimum) at each latitude. The interior communication is closely related to the ENSO cycle, and its rate and pathway have strong interannual–decadal variability.