The Mozambique channel revisited

Le flux méridien à travers le Canal de Mozambique est étudié en utilisant la différence entre les niveaux moyens des deux côtés du Canal et en estimant l'influence des composantes du vent mesuré sur deux îles basses situées dans le Canal. Les flux méridiens dans le nord et le sud du Canal de Mozambique sont à peu près en phase et le transport méridien est soumis à un cycle saisonnier. Trois croisières inédites (1974-1975) dans le Canal de Mozambique révèlent dans la partie nord (12°-16°S) un tourbillon anticyclonique soumis à des variations saisonnières et interannuelles et un fort flux portant au sud à l'endroit le plus étroit du Canal. (Résumé d'auteur

Mean annual variation of transport of major currents in the tropical Pacific Ocean

Expendable bathythermograph (XBT) data and the climatological temperature/salinity relationship were used to calculate the mean annual cycle of dynamic height and geostrophic transport of major currents relative to 400 db along five shipping tracks covering a large part of the tropical 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° latitude bins along the tracks. The transport function (vertically integrated dynamic height) was then calculated using the mean temperature/salinity relationship. The mean annual cycle of transport of the North Equatorial Current (NEC), the North Equatorial Countercurrent (NECC) and the South Equatorial Current (SEC) (south of 2.5°S) were determined between the ridges and troughs of the transport function. The stochastic errors in bimonthly mean transports were 1-2 Sverdrups on the most sampled tracks. Mean transports of the NEC and NECC increase regularly with longitude from east to west. The NECC has a large annual cycle with a transport-maximum during northern fall and winter. Seasonal variations of the NEC are small. Seasonal variations of the SEC are slightly 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 mean 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 facilitate future comparisons to ocean general circulation models and other applications. (Résumé d'auteur