Internal wave-wave interaction theories and observations support a parameterization for the turbulent dissipation rate and eddy diffusivity K that depends on internal wave shear ͗V z 2 ͘ and strain ͗ z 2 ͘ variances. Its latest incarnation is applied to about 3500 lowered ADCP/CTD profiles from the Indian, Pacific, North Atlantic, and Southern Oceans. Inferred diffusivities K are functions of latitude and depth, ranging from 0.03 ϫ 10 Ϫ4 m 2 s Ϫ1 within 2°of the equator to (0.4-0.5) ϫ 10 Ϫ4 m 2 s Ϫ1 at 50°-70°. Diffusivities K also increase with depth in tropical and subtropical waters. Diffusivities below 4500-m depth exhibit a peak of 0.7 ϫ 10 Ϫ4 m 2 s Ϫ1 between 20°and 30°, latitudes where semidiurnal parametric subharmonic instability is expected to be active. Turbulence is highly heterogeneous. Though the bulk of the vertically integrated dissipation ͐ is contributed from the main pycnocline, hotspots in ͐ show some correlation with small-scale bottom roughness and near-bottom flow at sites where strong surface tidal dissipation resulting from tide-topography interactions has been implicated. Average vertically integrated dissipation rates are 1.0 mW m Ϫ2 , lying closer to the 0.8 mW m Ϫ2 expected for a canonical (Garrett and Munk) internal wave spectrum than the global-averaged deep-ocean surface tide loss of 3.3 mW m Ϫ2 .

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[1] The supply of oxygen-rich water to the oxygen minimum zones (OMZs) of the eastern North and South Pacific via zonal tropical currents is investigated using shipboard acoustic Doppler current profiler and hydrographic section data. Near the equator, the Equatorial Undercurrent (EUC), Northern and Southern Subsurface Countercurrents (SCCs), and the Northern and Southern Intermediate Countercurrents (ICCs) all carry water that is oxygen richer than adjacent westward flows, thereby providing a net oxygen supply to the eastern Pacific OMZs. The synoptic velocity-weighted oxygen concentration difference between eastward and westward flows is typically 10-50 mmol kg −1 . Subthermocline zonal oxygen fluxes reflect decreasing oxygen concentrations of the EUC, the SCCs, and the ICCs as they flow eastward. Approximately 30 year time series in well-sampled regions of the equatorial Pacific show oxygen content decreasing as rapidly as −0.55 mmol kg −1 yr −1 in the major oxygen supply paths of the OMZs for a 200-700 m layer and similar trends for a density layer spanning roughly these depths. This finding is in gross agreement with climate models, which generally predict expanding OMZs.

The Western Equatorial Pacific Ocean Circulation Study (WEPOCS) III expedition was conducted from June 18 through July 31, 1988, in the far western equatorial Pacific Ocean to observe the low‐latitude western boundary circulation there, with emphasis on the Mindanao Current. This survey provides the first quasi‐synoptic set of current measurements which resolve all of the important upper‐ocean currents in the western tropical Pacific. Observations were made of the temperature, salinity, dissolved oxygen, and current profiles with depth; of water mass properties including transient tracers; and of evolving surface flows with a dense array of Lagrangian drifters. This paper provides a summary of the measurements and a preliminary description of the results. The Mindanao Current was found to be a narrow, southward‐flowing current along the eastward side of the southern Philippine Islands, extending from 14°N to the south end of Mindanao near 6°N, where it then separates from the coast and penetrates into the Celebes Sea. The current strengthens to the south and is narrowest at 10°N. Direct current measurements reveal transports in the upper 300 m increasing from 13 Sv to 33 Sv (1 Sverdrup = 1 × 106 m3 s−1) between 10°N and 5.5°N. A portion of the Mindanao Current appears to recurve cyclonically in the Celebes Sea to feed the North Equatorial Countercurrent, merging with waters from the South Equatorial Current and the New Guinea Coastal Undercurrent. Another portion of the Mindanao Current appears to flow directly into the NECC without entering the Celebes Sea. The turning of the currents into the NECC is associated with the Mindanao and Halmahera eddies.

Global ship-based programs, with highly accurate, full water column physical and biogeochemical observations repeated decadally since the 1970s, provide a crucial resource for documenting ocean change. The ocean, a central component of Earth's climate system, is taking up most of Earth's excess anthropogenic heat, with about 19% of this excess in the abyssal ocean beneath 2,000 m, dominated by Southern Ocean warming. The ocean also has taken up about 27% of anthropogenic carbon, resulting in acidification of the upper ocean. Increased stratification has resulted in a decline in oxygen and increase in nutrients in the Northern Hemisphere thermocline and an expansion of tropical oxygen minimum zones. Southern Hemisphere thermocline oxygen increased in the 2000s owing to stronger wind forcing and ventilation. The most recent decade of global hydrography has mapped dissolved organic carbon, a large, bioactive reservoir, for the first time and quantified its contribution to export production (∼20%) and deep-ocean oxygen utilization. Ship-based measurements also show that vertical diffusivity increases from a minimum in the thermocline to a maximum within the bottom 1,500 m, shifting our physical paradigm of the ocean's overturning circulation.

Upper-ocean horizontal velocity and divergence were estimated from shipboard observations taken from 1991 to 1999 in the equatorial Pacific between 170ЊW and 95ЊW. Mean transports were estimated for the zonal currents at the mean longitude of the sections, 136ЊW. Mean meridional currents for the entire longitude range included poleward surface flows reaching Ϫ0.09 m s Ϫ1 in the south and 0.13 m s Ϫ1 in the north as well as equatorward flow within the thermocline reaching 0.05 m s Ϫ1 in the south and Ϫ0.04 m s Ϫ1 in the north near 23ЊC (85 m). Vertical velocity was diagnosed by integrating horizontal divergence estimated for the entire region down from the surface. Equatorial upwelling velocities peaked at 1.9 (Ϯ0.9) ϫ 10 Ϫ5 m s Ϫ1 at 50 m. The upwelling transport in the area bounded by 3.6ЊS-5.2ЊN, 170ЊW-95ЊW was 62 (Ϯ18) ϫ 10 6 m 3 s Ϫ1 at 50 m. Strong downwelling was apparent within the North Equatorial Countercurrent. An asymmetry in the meridional flows suggested that on the order of 10 ϫ 10 6 m 3 s Ϫ1 of thermocline water from the Southern Hemisphere was upwelled at the equator and moved into the Northern Hemisphere as surface water. This interhemispheric exchange path could be part of the route for water from the Southern Hemisphere to supply the Indonesian Throughflow.

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