Properties of the Atlantic derived halocline waters over the Laptev Sea continental margin: Evidence from 2002 to 2009

A series of transects carried out in 2002-2009 across the Laptev Sea continental margin show consistent cross-slope differences of the lower halocline water (LHW). Over the slope the LHW core is on average warmer and saltier by 0.39 degrees C and 0.26 practical salinity unit, respectively, relative to the off-slope LHW. Underlying Atlantic water (AW) thermohaline properties exhibit an opposite pattern; it is colder and fresher over the slope and warmer and saltier off the slope. Although on-slope and off-slope LHWs have different formation histories, our results suggest that an important part of the heat and salt lost from the AW is gained by the overlying LHW over the continental slope area. This implies the role of enhanced vertical mixing over the sloping topography, which contributes to the difference between the on-and off-slope LHW properties. The distribution of chemical tracers (dissolved oxygen and nutrients) provides further evidence supporting this interpretation and additionally suggests that the LHW may also be influenced by water from the outer shelf.