SGER: Modeling Heat Exchange between Arctic Leads and Underlying Water Utilizing Be7 Measurements

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9809168 Kadko One of the important unknowns in the summer surface energy balance of the Arctic Ocean involves the fate of the energy inputs (mostly shortwave radiation) in the heterogeneous ice-ocean system during the melt season. Downwelling solar radiation is the primary source for the direct heating of the ocean through leads, but the fate of the solar energy absorbed through the leads is not adequately known. To understand the ice-albedo feedback, one must know how the energy is partitioned between lateral melting of floe edges, bottom melting of ice, or warming of the water column. In this work, the heat exchange between the leads and underlying mixed layer will cosmic ray produced species which is delivered to the earth's surface, and as such can be used as a proxy for incoming solar radiation. Because it has a known decay rate, it can be used to estimate the mean exposure time of lead water to solar insolation, and the delivery rate of solar energy to the ice bottom. The mean life of the isotope is 77 days, and thus it is an ideal tracer for evaluating seasonal processes. Samples for this analysis were collected as part of the initial SHEBA (Surface Heat Budge of the Arctic Ocean) field program, and measurement of Be-7 were successfully made. These are the first measurements of this isotope ever made under the Arctic ice.