Download Tracing Arctic Ocean Near-Surface Waters E P Jones (Department

Tracing Arctic Ocean Near-Surface Waters
E P Jones (Department of Fisheries and Oceans, Bedford Institute of
Oceanography, Dartmouth NS B2Y 4A2 Canada; ph. 902-426-3869;
fax 902-426-7827; email: [email protected]); B Rudels
(Finnish Institute of Marine Research, FIN-00931 Helsinki, Finland;
ph. + 358 9 61394428; fax 358 9 331025; email: [email protected])
Potential changes in the permanent ice cover and the freshwater budget
of the Arctic Ocean are directly relevant to questions of global climate
change. The Arctic Ocean halocline prevents the heat in the Atlantic
Layer from reaching the Polar Mixed Layer and melting the ice.
Freshwater from rivers and from the Pacific Ocean impact the amount
of deep convection that occurs in the Nordic and Labrador seas. We
trace the formation and circulation of the halocline and trace Pacific
source water as it flows thought the Arctic Ocean and into the North
Atlantic Ocean.
According to a recent view, the halocline is formed as Atlantic water
enters through Fram Strait encounters ice to become fresher and colder.
This Fram Strait branch subsequently becomes capped by fresher layer
containing river runoff, thus forming the Lower Halocline. An
additional contribution comes from Pacific water that is modified in the
shallow shelf seas north of Siberia forms the Upper Halocline. We
have identified a second source of Lower Halocline water, which
originates in the Barents Sea. This Barents Sea branch closely flows
close to the Eurasian coast in the Makarov Basin and Canada Basin
north of the Alpha-Mendeleyev Ridge, then spreading and making up
most of the Lower Halocline in the southern Canada Basin. All three
halocline components can be seen exiting the Arctic Ocean through
Fram Strait east of Greenland.
The near surface (top 100 m) water leaving the Arctic Ocean through
the Canadian Arctic Archipelago and through Fram Strait is nearly
100% Pacific source water with some additional river runoff and sea
ice meltwater. The river runoff plus sea ice meltwater component can
be distinguished in plots of the Pacific fraction vs. salinity.