Jr. Donguy et G. Meyers, OBSERVATIONS OF GEOSTROPHIC TRANSPORT VARIABILITY IN THE WESTERN TROPICAL INDIAN-OCEAN, Deep-sea research. Part 1. Oceanographic research papers, 42(6), 1995, pp. 1007-1028
Dynamic height was calculated from XBTs collected along several shippi
ng routes in the western Indian Ocean. In the northern hemisphere, low
dynamic heights prevail during the NE monsoon and high dynamic height
s during the SW monsoon inducing an alternating Somali Current. In the
southern hemisphere, at 7 degrees-8 degrees S a trough of low dynamic
height occurs during the whole year. EOF analysis is used to document
the variation of these features. The geostrophic transports calculate
d for the XBT routes show spatially coherent patterns with strong seas
onal variations. In the Arabian Sea, an anticlockwise gyre develops du
ring the NE monsoon alternating with a clockwise gyre during the SW mo
nsoon. Between 5 degrees N and 5 degrees S, the transport variations s
how eastward flow twice each year during the monsoon transitions, exce
pt on the westernmost route where the annual variations of the gyre in
the Arabian Sea extend to the equator. The mean transport of the Sout
h Equatorial Current increases regularly with longitude from east to w
est in all months. It has small annual variations, and the phase of th
e annual maximum progresses consistently westward.