Fresh Water Fluxes

The Arctic Ocean contains, relative to its surface, very much fresh water (salinity = 0). 

Ocean and sea ice are the big fresh water reservoirs of the Arctic Ocean. The ocean water over there has a much lower salinity than the medium salinity of the world ocean. In Arctic ocean stores the fresh water in liquid form. By freezing and melting ocean and sea ice are in close exchange. Important fresh water transport also occurs between different regions of the Arctic ocean.

River water reaches from the estuaries of the big Siberian rivers to Fram- and Davis straits, the passages from the Arctic ocean in the sub-polar Atlantic. Low salinity water and sea ice interrupt the usual intensive vertical exchange and therefore the sinking of dense water masses in the Nordic seas with probable impact on the global ocean circulation.

We try to quantify the exchange between the ocean and sea ice by an extensive drift buoys programme. Furthermore the buoys assist to visualize the pathways of sea ice. Together with the section ‘Physical Oceanography of Polar Seas’ of AWI we work on the fresh water fluxes through Fram Strait. Measurements of sea ice thickness and estimates of sea ice velocity are combined here. Experiments with numerical models are essential to understand the involved processes.

Time serie of changes of fresh water content within the central Arctic (1992 – 2012). 
The green stars mark observational data, red dots the very similar development of the model NAOSIM. The grey lines show the trend of 600 +- 300km**3/year. This finding is the result of the cooperation between observational oceanography and numerical modelling at AWI (Rabe et al., Geophysical Research Letters, 2014).
The time serie shows changes of fresh water content in the central Arctic (Graphic: B. Rabe, AWI)