Upwelling along the Java-Sumatra Indian Ocean coasts is a response to regio
nal winds associated with the monsoon climate. The upwelling center with lo
w sea surface temperature migrates westward and toward the equator during t
he southeast monsoon (June to October). The migration path depends on the s
easonal evolution of alongshore winds and latitudinal changes in the Coriol
is parameter. Upwelling is eventually terminated due to the reversal of win
ds associated with the onset of the northwest monsoon and impingement of In
dian Ocean equatorial Kelvin waves. Significant interannual variability of
the Java-Sumatra upwelling is linked to ENSO through the Indonesian through
flow (ITF) and by anomalous easterly wind. During El Nino episodes, the Jav
a-Sumatra upwelling extends in both time (into November) and space (closer
to the equator). During El Nino (La Nina), the ITF carries colder (warmer)
water shallowing (deepening) thermocline depth and enhancing (reducing) upw
elling strength.