Observations and modeling of dense water cascading from the Laptev Sea shelfстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 27 ноября 2016 г.
Аннотация:We examine dense water cascading from the northwestern Laptev Sea shelf in the
Arctic Ocean. This region is believed to be a potential site of dense water formation
through ice freezing and brine ejection. Climate data indicate the presence of saltier/denser
water on the shelf all year round. Tongues of dense water spreading from the shelf to the
continental slope and reaching a depth of 300–400 m are reported in some historical
hydrographic surveys. In this study we recreate dense water cascading from the Laptev
Sea shelf by filling a gap between two sequential hydrographic surveys with numerical
model output. From October 1984 to April 1985, ice formation over the shelf provided salt
input almost 5 times greater than the amount that was accumulated in the shelf waters.
This excessive salt was transported off the shelf mainly by baroclinic eddies and also by
mean outflow through the bottom boundary layer. Shelf origin dense water would have
reached at least 1000-m depth, but strong stratification prevented it from penetrating
deeper than 400 m downslope. Contribution of mean downslope flow to heat and salt
exchange between shelf and slope is on the average 4 times smaller than that caused by
eddy fluxes. Hence, although the volume transport associated with cascading is relatively
small (0.02 Sv), heat and salt fluxes are large enough to provide cooling and freshening
of Atlantic Water, which propagates along the Siberian continental slope.