Js. Godfrey, THE EFFECT OF THE INDONESIAN THROUGHFLOW ON OCEAN CIRCULATION AND HEAT-EXCHANGE WITH THE ATMOSPHERE - A REVIEW, J GEO RES-O, 101(C5), 1996, pp. 12217-12237
A new version of the island rule, which relates transport aound an isl
and to wind and pressure forcing, provides a basis for comparing vario
us published theoretical estimates of the long-term mean Indonesian th
roughflow magnitude. It is found, among other things, that nonlinear e
ffects near Halmahera and pressure gradients across New Zealand may mo
dify the long-term throughflow magnitude. Recent theoretical estimates
of interannual throughflow variations are in approximate agreement wi
th observation; Indian Ocean Kelvin waves play an important role. On s
till shorter timescales and for understanding flow details in differen
t channels, consideration of the full details of the Indonesian region
via numerical modeling becomes essential. Most of the throughflow ent
ers from the Mindanao Current. The process by which the South Pacific
waters eventually reach the Mindanao Current appears to involve some n
onlinear retroflection process (particularly in northern summer) and s
ubsequent freshening along long pathways in the North Pacific. Observe
d water mass transformations in Indonesian waters demand a vertical ed
dy diffusivity of about 10(-4) m(2) s(-1), large enough to generate tu
rbulent heat fluxes of order 40 W m(-2) at the base of the mixed layer
. According to numerical models, changes in ocean circulation associat
ed with the throughflow are likely to affect patterns of heat exchange
with the atmosphere in widely separated regions of the world ocean. I
n particular, an increased throughflow will result in more heat loss t
o the atmosphere in the subtropical Indian Ocean and less in the Pacif
ic Ocean. Simple, physically reasonable mechanisms have been offered f
or these model results. Observational evidence to support or refute th
ese mechanisms is rather fragmentary but is reviewed here. Our present
understanding of the throughflow permits some informed speculations a
s to the possible role of the throughflow in coupled ocean-atmosphere
phenomena such as the El Nino-Southern Oscillation (ENSO). Earlier est
imates of western Pacific reflectivity seem largely confirmed by recen
t observational results. However, it is suggested that tidal mixing in
the Indonesian seas may generate ENSO-related sea surface temperature
anomalies there, possibly affecting the development of westerly wind
bursts.