Benjamin Rabe et al., Deep Sea Research 58 (February 2011), An assessment of Arctic Ocean freshwater content changes from the 1990s to the 2006–2008 period

Deep Sea Research Part I: Oceanographic Research Papers,
Vol. 58, No. 2 (February 2011) 173-185; doi: 10.1016/j.dsr.2010.12.002 




An assessment of Arctic Ocean freshwater content changes from the 1990s to the 2006–2008 period

Benjamin Rabe^a, , , , Michael Karcher^a, Ursula Schauer^a, John M. Toole^b, Richard A. Krishfield^b, Sergey Pisarev^c, Frank Kauker^a, Rüdiger Gerdes^a and Takashi Kikuchi^d

^a Alfred Wegener Institute for Polar and Marine Research, Bussestr. 24, Postfach 120161, 27515 Bremerhaven, Germany

^b Woods Hole Oceanographic Institution, USA

^c Shirshov Institute of Oceanology, Russia

^d Japan Agency for Marine-Earth Science and Technology, Japan

Received 21 December 2009;  

revised 7 November 2010;  

accepted 2 December 2010.  

Available online 15 December 2010. 

Abstract

Unprecedented summer-season sampling of the Arctic Ocean during the period 2006–2008 makes possible a quasi-synoptic estimate of liquid freshwater (LFW) inventories in the Arctic Ocean basins. In comparison to observations from 1992 to 1999, LFW content relative to a salinity of 35 in the layer from the surface to the 34 isohaline increased by 8400±2000 km³ in the Arctic Ocean (water depth greater than 500 m). This is close to the annual export of freshwater (liquid and solid) from the Arctic Ocean reported in the literature.

Observations and a model simulation show regional variations in LFW were both due to changes in the depth of the lower halocline, often forced by regional wind-induced Ekman pumping, and a mean freshening of the water column above this depth, associated with an increased net sea ice melt and advection of increased amounts of river water from the Siberian shelves. Over the whole Arctic Ocean, changes in the observed mean salinity above the 34 isohaline dominated estimated changes in LFW content; the contribution to LFW change by bounding isohaline depth changes was less than a quarter of the salinity contribution, and non-linear effects due to both factors were negligible.

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