Woods Hole Oceanographic Institution

Steven R. Jayne

»Sc.D. Thesis
»Recirculation gyres in a beta-plane jet
»Forcing and sampling of ocean models
»Thermohaline circulation - sea ice feedback
»Recirculation forced by an unstable jet
»Tidal dissipation over rough topography
»Dynamics of ocean heat transport variability
»Deep ocean currents from GRACE
»Estimates of tidally-driven mixing
»Millennial climate variability
»Oceanic eddy heat transport
»Ocean heat content from GRACE
»Tidally-driven mixing in an ocean model
»Ocean bathymetry and Earth's climate
»Bathymetry from space
»Subtropical mode water during KESS
»North Atlantic Ocean circulation from GRACE
»Subtropical mode water in the Kuroshio Extension
»Tidal mixing during the Last Glacial Maximum
»Kuroshio northern recirculation gyre
»Bottom pressure in KESS and GRACE
»Ocean model metrics
»Abyssal mixing in CCSM
»Kuroshio Extension jet and transport
»The Morphology of Steve

S. R. Jayne , Sc.D. Thesis: Dynamics of global ocean heat transport variability , 1999

A state-of-the-art, high-resolution ocean general circulation model is used to estimate the time-dependent global ocean heat transport and investigate its dynamics. The north-south heat transport is the prime manifestation of the ocean's role in global climate, but understanding of its variability has been fragmentary owing to uncertainties in observational analyses, limitations in models, and the lack of a convincing mechanism. These issues are addressed in this thesis. Technical problems associated with the forcing and sampling of the model, and the impact of high-frequency motions are discussed. Numerical schemes are suggested to remove the inertial energy to prevent aliasing when the model fields are stored for later analysis. Globally, the cross-equatorial, seasonal heat transport fluctuations are close to ±4.5 x 1015 watts, the same amplitude as the seasonal, cross-equatorial atmospheric energy transport. The variability is concentrated within 20o of the equator and dominated by the annual cycle. The majority of it is due to wind-induced current fluctuations in which the time-varying wind drives Ekman layer mass transports that are compensated by depth-independent return flows. The temperature di erence between the mass transports gives rise to the time-dependent heat transport. The rectified eddy heat transport is calculated from the model. It is weak in the central gyres, and strong in the western boundary currents, the Antarctic Circumpolar Current, and the equatorial region. It is largely confined to the upper 1000 meters of the ocean. The rotational component of the eddy heat transport is strong in the oceanic jets, while the divergent component is strongest in the equatorial region and Antarctic Circumpolar Current. The method of estimating the eddy heat transport from an eddy di ffusivity derived from mixing length arguments and altimetry data, and the climatological temperature field, is tested and shown not to reproduce the model's directly evaluated eddy heat transport. Possible reasons for the discrepancy are explored.

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