the Eurasian sector of the Arctic interior noted by others (Steele and Boyd, 1998), Atlantic waters entering the Arctic in this time frame were actually freshened by unusually high precipitation in the Svalbard-Barents Sea sector and so cannot be the explanation of the salinification (R. Dickson, personal communication). However, under the 1989-94 scenario, Eurasian river waters tend to transit further along-shelf before entering the interior and therefore are unavailable to dilute waters directly offshore of their mouths. If our data do indeed represent a regime shift in 1995, we expect the cold halocline layer to return with a 1 to 2 year time lag.
5. FUTURE DIRECTIONS
In summer of 1997, we participated in a modern hydrographic tracer survey that transited the Canadian Archipelago and included transects of all of the major passages to Baffin Bay and the Labrador Sea. We are presently engaged in the analyses of these samples as well as ones from ongoing ships of opportunity within the Arctic. The Archipelago work is expected to help determine how passage through its complex channels transforms tracer signals originating in the Beaufort Gyre.
Our findings to date suggest that the insights to be gained by tracer distributions tend to be limited by sampling resolution in both time and space. For this reason, we are turning our attention to timed-sampler systems that can be deployed on moorings and have begun efforts to use and develop in-situ sensors. In collaboration with others, we have recently obtained the first results for in-situ sensing for terrestrially derived dissolved organic carbon in the Arctic. Measurement was accomplished via a fiber optic zero angle spectrometer system (Klinkhammer, 1994) mounted on the hull of a nuclear submarine. Even a preliminary analysis demonstrate the considerable strides to be made by such an approach.
6. REFERENCES
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