Sources and fate of freshwater exported in the East Greenland Current

Abstract

Monitoring the sources and fate of freshwater in the East Greenland Current (EGC) is important, as this water has the potential to suppress deep convection in the Nordic and Labrador Seas if the outflow of freshwater from the Arctic Ocean increases in response to climate change. Here, hydrographic, oxygen isotope ratio and dissolved barium concentration sections across Denmark Strait collected in 1998 and 1999 are used to determine the freshwater composition of the EGC at these times. Comparison of meltwater fluxes at Denmark Strait and Fram Strait indicates a net melting of sea ice into the EGC between these two locations, with a significant proportion of sea ice drifting into the Nordic Seas or on to the East Greenland Shelf. We conclude that the phase of freshwater exiting the Arctic Ocean through Fram Strait is important in determining its possible impact on deep water formation in the Nordic and Labrador Seas

Liquid export of Arctic freshwater components through the Fram Strait 1998–2011

“…5) is about 2:1 in all of our surveys, except 1998. Previous studies have found that a similar ratio of MW to FIFB is generally observed in station or section inventories (Meredith et al, 2001;Dodd et al, 2009;Rabe et al, 2009) and section transports (Rabe et al, 2009). This has been attributed to processes in the Arctic Ocean "upstream" from the Arctic outflow in the Fram Strait.…”

“…This method uses a system of linear equations (endmember balance) to derive the aforementioned water mass fractions and fractions of Atlantic Water (AW) from each observed tracer, assuming certain end-member values for each tracer (see also Ekwurzel et al, 2001;Jones et al, 2008a;Yamamoto-Kawai et al, 2008). In addition to further years of observations, the main difference to previous work (Dodd et al, 2009;Rabe et al, 2009) is the inclusion of nitrate and phosphate observations to distinguish PW in the end-member balance. δ 18 O for the SIM end-member was set to a constant value, rather than relating it to the surface value of each profile.…”

“…Dodd et al (2012) extended the work by Meredith et al (2001), Dodd et al (2009) and Rabe et al (2009), adding further years of observations and distinguishing Pacific Water fractions (concentrations) by considering nutrient measurements in addition to δ 18 O and salinity.…”

“…Previous work has shown that the composition of the southward liquid freshwater transport in the EGC is influenced not only by processes in the Western Fram Strait but also by the circulation in the Arctic Ocean (Meredith et al, 2001;Dodd et al, 2009;Rabe et al, 2009;Jahn et al, 2010). The pathways of freshwater in the Arctic Ocean and their arrival in the Fram Strait are related to both the large-scale atmospheric circulation influencing upper ocean currents and hydrography (Proshutinksy and Johnson, 1997;Steele and Boyd, 1998;Zhang et al, 2003;Häkkinen and Proshutinsky, 2004;Dukhovskoy et al, 2006), and regional processes governing the storage and release of liquid freshwater.…”

Origin of freshwater and polynya water in the Arctic Ocean halocline in summer 2007

“…An approximately constant ratio between inventories of f i and f r has been observed before, e.g. in the region of export of Arctic Ocean halocline waters within the western Fram Strait areas (Dodd et al, 2009;Rabe et al, 2009;Meredith et al, 2001;Bauch et al, 1995) The whole 2007 dataset from the Eurasian and Makarov basins shows a wide range of f i to f r ratios, which depend on salinity and corresponding depth level within the halocline (Fig. 9), and on the regional origin too (Fig.…”