Fresh Water Increase in Arctic

This coincides with the loss ofsea ice over the same time period and must be seen as a corollary to that.  I would like to see the numbers refined butthat is not possible and there is plenty of controversyover what has been happening since.

Reports suggested a steady lossof mass, yet Navy reports claim quite the reverse.

We have lost a lot of ice andthis year will surely clarify a great deal. It may confirm the ice recovery or even the reverse.  It continues to be a tough call and thepromising open seas of two years ago may never repeat.

The whole issue of what ishappening is that something is certainly happening, but annual data merely confusesbecause we are looking too closely at the data.

Large-Scale Assessment Of ArcticOcean ShowSignificant Increase In FreshwaterContent

by Staff Writers

Bremerhaven, Germany (SPX) Mar 29, 2011

Differences in the mean salinity of the Arctic Ocean above the 34 isohaline between 2006 to 2008 and 1992 to1999. Negative values are shown in yellow, green, and blue and stand for anincrease of freshwater. Image: Benjamin Rabe, Alfred WegenerInstitute.

http://www.terradaily.com/reports/Large_Scale_Assessment_Of_Arctic_Ocean_Show_Significant_Increase_In_Freshwater_Content_999.html

The freshwater content of the upper Arctic Oceanhas increased by about 20 percent since the 1990s. This corresponds to a riseof approx. 8,400 cubic kilometres and has the same magnitude as the volume offreshwater annually exported on average from this marine region in liquid orfrozen form.

This result is published by researchers of the Alfred Wegener Institutein the journal Deep-Sea Research. The freshwater content in the layer of the Arctic Ocean near the surface controls whether heat fromthe ocean is emitted into the atmosphere or to ice. In addition, it has animpact on global ocean circulation.

Around ten percent of the global mainland runoff flows into the Arctic via the enormous Siberian and North Americanrivers in addition to relatively low-salt water from the Pacific. Thisfreshwater lies as a light layer on top of the deeper salty and warm oceanlayers and thus extensively cuts off heat flow to the ice and atmosphere.Changes in this layer are therefore major control parameters for the sensitiveheat balance of the Arctic.

We can expect that the additional amount of freshwater in thenear-surface layer of the Arctic Ocean will flow out into the North Atlantic in the coming years. The amount of freshwater flowing outof the Arctic influences the formation of deep water in the Greenland Sea and Labrador Sea and thus has impacts on global oceancirculation.

Dr. Benjamin Rabe from the Alfred Wegener Institute for Polar andMarine Research in the Helmholtz Association and his colleagues have evaluateda total of over 5,000 measured salt concentration profiles.

To measure the depth distribution of the salt concentration,researchers used sensors from ships or mounted sensors on large ice floes sothe data were recorded during the ice drift through the Arctic Ocean.

Furthermore, measured values from submarines were inputted in theanalyses. Major portions of the data stem from expeditions during International Polar Year 2007/2008.

"The well coordinated research programmes in the Arctic havesubstantially improved the database in these difficult to access areas,"reports Rabe, who will again sail to the central Arctic on the research vesselPolarstern in the coming summer.

The dense network of observations in recent years made it possible forthe first time to come up with a comparative assessment of the freshwatercontent in the Arctic Ocean.

Rabe and his colleagues have published the increase in the freshwatercontent between the periods 1992 to 1999 and 2006 to 2008 in the journalDeep-Sea Research. "The considerable changes in the upper water layersprimarily comprise a decline in salt concentration," says Rabe. Another,though minor, effect is that the low-salt layers are thicker than before.

The freshwater content of the Arctic Oceanmay rise due to increased seaice or glacier melt, precipitation or river inputs. Less export offreshwater from the Arctic - in the form ofsea ice or in liquid form - also results in a rise in the freshwater content.

The authors of the study point to altered export of freshwater andaltered inputs from near-coastal areas in Siberia to the central Arctic Ocean as the most probable reasons.

Dr. Michael Karcher from the Alfred Wegener Institute, co-author of thestudy, simulated the observed processes using the NAOSIM coupled ocean/sea icemodel. The model experiments make it possible to study longer periods, i.e. tomap times for which no measurement data are available.

The model also supplies important insights into the causes of therising and falling freshwater content and points out the great significance ofthe local wind field. Measurements and the model additionally show that thechanges in the Arctic freshwater content encompass far larger areas thanassumed to date.

The title of the original publication by Benjamin Rabe, MichaelKarcher, Ursula Schauer, John M. Toole, Richard A. Krishfield, Sergey Pisarev,Frank Kauker, Rudiger Gerdes and Takashi Kikuchi is: "An assessment ofArctic Ocean freshwater content changes from the 1990s to the 2006-2008period" and appeared in the journal Deep-Sea Research I 58 (2011) 173-185(doi:10.1016/j.dsr.2010.12.002).