Collaborative Research: Quantifying the Spatial/Temporal Variability of the Arctic Cold Halocline and Ice-Ocean Interaction

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There has been a significant change in the upper ocean characteristics of the eastern Arctic in 1995. The change was manifested through the loss of a near-surface layer known as the cold halocline layer (CHL). Without the CHL, the Arctic water column looks and behaves like the Antarctic water column. The local impact involves the likely initiation of considerable winter ocean heat fluxes (15-20 W/m 2 ) and reduction of winter ice growth by 70-80% relative to previous years in which the CHL was present. It is not known how long the CHL did, or will, remain absent, though it appears to begun recovery by summer 1999. This project will examine CTD stations throughout the Arctic region in order to quantify the strength of the CHL as well as other seasonally-averaged characteristics of the ocean-ice interaction (e.g., ocean heat flux, bulk stability, reduction in ice growth potential). The quantification is achieved through analysis of upper ocean integrated property distributions, and then generating robust bulk property parameters describing relevant physical quantities. The methodology was originally designed for analysis of Antarctic ice-ocean interaction, but as recently shown, is equally applicable to the Arctic. Once applied to the Arctic data, the parameters will be averaged to provide climatologies for the various properties. The spatial distribution of these climatologies will be compared to physical and dynamical properties of the Arctic in an attempt to determine the relationship between the climatological nature of the ocean-ice interaction and the physical/dynamical setting. Methods of optimal interpolation will then be applied, to the extent allowed by the sporadic data coverage, in an effort to determine how the various integrated properties have changed through space and time. This will provide spatial/temporal distributions of the ocean-ice interaction that will be used to evaluate the manner in which the CHL and other ocean-ice interactions have changed. The temporal variations will be examined for evidence of cycles, trends, or other coherent patterns, as have been suggested recently in the literature. Analysis of ocean data is ideal for this undertaking given the long time scales of the medium which may reveal evidence of the suspected changes even in sparsely sampled (in space and time) regions.