Research Summaries

Back Diffusive Convection: Dynamics, Transport, and Interaction with Large-Scale Patterns

Fiscal Year 2018
Division Graduate School of Engineering & Applied Science
Department Oceanography
Investigator(s) Radko, Timour
Sponsor National Science Foundation (NSF)
Summary Diffusive convection plays an important role in diapycnal mixing of heat and salt in several key regions potentially affecting the large-scale dynamics and climate of high-latitude oceans. However, several fundamental properties of diffusive convection, and its spectacular manifestation in the form of thermohaline staircases, still have not been fully explained. The unresolved theoretical questions include the origin of diffusive staircases, the mechanism for selecting vertical extent of layers, and the interaction of diffusive convection with internal waves. Thus, it is vital to improve our understanding of the physical mechanisms of diffusive convection, quantify its transport characteristics, and determine its ability to affect basin-scale circulation patterns. This challenge is met by the proposed comprehensive program of theoretical and numerical studies of diffusive convection in realistic time-dependent shears representative of the environments in the Arctic and sub-Antarctic waters. A hierarchy of models, which include direct numerical simulations (DNS) and basin-scale experiments, will be analyzed to reveal the key physical processes at play. Numerical studies will be supplemented by illustrative analytical models and the analysis of field data. Specific research tasks include the following: (i) the development of explicit parameterizations for the diffusive diapycnal transport of heat and salt in time-dependent (subcritical and supercritical) shears, (ii) the identification of the dominant physical processes that induce thermohaline layering, (iii) the determination of specific environmental conditions favoring staircase formation in diffusively stratified water masses, and (iv) the assessment of the impact of diffusive convection on largescale circulation patterns.
Keywords Mixing ocean dynamics
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Data Publications, theses (not shown) and data repositories will be added to the portal record when information is available in FAIRS and brought back to the portal