| Summary: | Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2010. This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. Cataloged from student submitted PDF version of thesis. Includes bibliographical references (p. 262-277). Sea ice (SI) and ocean variability in marginal polar and subpolar seas are closely coupled. SI variability in the Labrador Sea is of climatic interest because of its relationship to deep convection/mode water formation, carbon sequestration, and Northern Hemisphere atmospheric patterns. Historically, quantifying the link between the region's observed SI and oceanic variability has been limited due to in situ observation paucity and technical challenges associated with synthesizing ocean and SI observations with a three-dimensional time-evolving dynamically consistent numerical model. To elaborate upon the relationship between SI and ocean variability, a one year (1996- 1997) state estimate of the ocean and sea ice state in Labrador Sea and Baffin Bay is constructed and analyzed. The estimate is a synthesis of a regional coupled 32 km ocean and sea ice model with a suite of contemporary in situ and satellite hydrographic and SI data. The synthesis of SI data is made possible with the (novel) adjoint of a thermodynamic SI model. Model and data are made consistent, in a least-squares sense, by iteratively adjusting several control variables, such as ocean initial and lateral open boundary conditions and the atmospheric state, to minimize an uncertainty-weighted model-data misfit cost function. It is shown that the SI pack attains a state of quasi-equilibrium in mid-March during which net SI growth/melt approaches zero; newly-formed SI diverges from coastal areas and converges, via wind/ocean forcing, in the marginal ice zone (MIZ). It is further shown that SI converging in the MIZ is primarily ablated by turbulent ocean-SI enthalpy fluxes. The ...
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