J. Sprintall et al., A semiannual Indian Ocean forced Kelvin wave observed in the Indonesian seas in May 1997, J GEO RES-O, 105(C7), 2000, pp. 17217-17230
Recent observations within the Indonesian exit passages and internal seas h
ighly resolve the arrival and passage of a semiannual Kelvin wave. In mid-M
ay 1997, surface and subsurface currents were to the southeast at a mooring
located south of Java in the South Java Current, while local wind forcing
was northwestward. Subsequent northward fluctuations in the geostrophic cur
rent through Lombok Strait and in observed currents from two moorings locat
ed in Makassar Strait are commensurate with the speed and passage of a Kelv
in wave through the region. The Kelvin wave was due to westerly wind forcin
g in the remote equatorial Indian Ocean during the semiannual April/May mon
soon transition period. This was confirmed through a simple remote wind-for
ced analytical Kelvin wave model of velocity at the South Java Current moor
ing location and sea level in Lombok Strait and also in the numerical gener
al circulation model of Murtugudde et al. [1998]. Warm temperature anomalie
s measured at the south Java mooring and within Makassar Strait an associat
ed with the passage of the Kelvin wave. Salinity anomalies measured at the
south Java mooring are consistent with an Indian Ocean source. The observed
passage of the Kelvin wave during May 1997 unambiguously demonstrates for
the first time that equatorial Indian Ocean remote wind forcing may on occa
sions influence the internal Indonesian seas.