Jr. Donguy et G. Meyers, MEAN ANNUAL VARIATION OF TRANSPORT OF MAJOR CURRENTS IN THE TROPICAL PACIFIC-OCEAN, Deep-sea research. Part 1. Oceanographic research papers, 43(7), 1996, pp. 1105-1122
Expendable bathythermograph (XBT) data and the climatological temperat
ure/salinity relationship were used to calculate the mean annual cycle
of dynamic height and geostrophic transport of major currents relativ
e to 400 db along live shipping tracks covering a large part of the tr
opical Pacific Ocean. The data were selected in bands centered on the
most frequently repeated XBT tracklines for the period 1967-1988. Long
-term bimonthly mean temperature was calculated in 1 degrees latitude
bins along the tracks. The transport function (Vertically integrated d
ynamic height) was then calculated using the mean temperature/salinity
relationship. The mean annual cycle of transport of the North Equator
ial Current (NEC), the North Equatorial Countercurrent (NECC) and the
South Equatorial Current (SEC) (south of 2.5 degrees S) were determine
d between the ridges and troughs of the transport function. The stocha
stic errors in bimonthly mean transports were 1-2 Sverdrups on the mos
t sampled tracks. Mean transports of the NEC and NECC increase regular
ly with longitude from east to west. The NECC has a large annual cycle
with a transport-maximum during northern fall and winter. Seasonal va
riations of the NEC are small. Seasonal Variations of the SEC are slig
htly larger, and they have considerably different phase from track to
track. The variation of thermal structure associated with the currents
is described. The results of this study are compared in detail to the
results of earlier studies of the transports. The differences between
the studies are larger than the expected stochastic errors in the mea
n transports due to differences in the definition of boundaries of the
currents and to differences in the procedure for calculating the mean
annual variation. The results of all the studies are summarised to fa
cilitate future comparisons to ocean general circulation models and ot
her applications. Copyright (C) 1996 Elsevier Science Ltd.