Sea-Surface Stress Variability in the Boundary Layer.
1997
Lambert, Bruce A | Jr
There is great potential for the use of satellite- or aircraft-borne synthetic aperture radar (SAR) imagery for analysis of meteorological systems. However, the interpretation of SAR imagery requires increased understanding of processes that change the state of the sea surface. Wind stress that results from kilometer-scale boundary layer spanning eddies (BLSE) produces sea-surface stress patterns responsible for some of this sea-surface variability. In this study, a Galerkin model of these BLSE, which take the form of two- dimensional rolls or three-dimensional convective cells, is modified with new boundary conditions to study their effect on sea-surface stress. The marine atmospheric boundary layer model used here allows subgrid-scale heat and momentum fluxes at the lower boundary and has been shown in a previous study to capture much of the qualitative behavior of BLSE circulations. However, the model solution in this study had a maximum vertical velocity at the lower boundary that prevented the fluxes from being physically correct, and the solution did not equilibrate owing to an unknown energy source. The goal of this thesis is to investigate hypotheses concerning how these problems can be solved. These hypotheses are derived from an energetics analysis of the model equations that leads to the introduction of new lower boundary conditions to control the boundary energy terms. The model is then applied in a case study using Hi-Res 2 data as initial conditions to determine the velocity fields at the lower boundary that produce kilometer-scale sea-surface stress variability and to compare this pattern with that found on an ERS-l SAR image.
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