This proposal is a renewal of OCE-0926481 Horizontal Convection: The Role of Turbulence. Horizontal convection (HC) is the generic designation for the circulation resulting from differential heating along one horizontal boundary of a fluid. The full problem of the Meridional Overturning Circulation is complex and difficult, involving thermal, haline and mechanical forcing. We have been working on understanding single-component horizontal convection, which is commonly viewed as a simplified conceptual model of the MOC. Our work in OCE-0926481, and that of other groups, suggest that the gap between HC and the ocean is not only quantitative, but also qualitative, Hence the title “Beyond Horizontal Convection.” The goal of this proposal is to move from the overly simplified problem of HC toward the richer dynamical setting of the ocean.
We plan to carry out laboratory and numerical experiments to understand this progression. We will address the following hypotheses (among others).
- Deep stratification is largely set by the interaction between the vertical transport of buoyancy in the depth-varying, negatively buoyant plume and the lateral transport due to baroclinic eddies.
- Kinetic energy dissipation in RHC with and without surface stress occurs primarily in the interior of the flow and is not due to bottom drag.
- An input of mechanical energy in the form of a surface stress in opposition to a buoyancy-driven circulation leads to a two-cell circulation, in which the system is no longer governed by classical scaling arguments.
- In the thermally indirect configuration, Ekman pumping tilts isopycnals, increasing available potential energy. The relative phase between wind and buoyancy forcing is hence important.
We will continue the educational activities of OCE-0926481. The renewal will provide continued funding for two graduate students to finish their thesis research and acquire skills in laboratory work and computational fluid dynamics. To reach pre-college students, we will continue to contribute to the professional development of high school teachers in the San Diego Unified School District. In partnership with the NSF-funded Center for Ocean Science Education Excellence – California we will sponsor a one-day workshop for approximately 25 Earth sciences teachers.
The numerical simulations in this project will be used as examples in a seminar class on scientific computing, aimed at introduce graduate students carrying out computational theses at SIO to the NSF supercomputing facilities. The class was first offered in Spring 2012. We have received dedicated NSF supercomputing resources for it and plan to offer it again in 2013.
The results of the proposed research have applications in industry and to environmental sustainability, as well as in related fields. The experiments carried out here are relevant to natural ventilation of buildings, which can inform critical energy conservation efforts that may ultimately benefit society economically, environmentally and politically.