Stability and forcing of the Iceland-Faroe inflow of water, heat, and salt to the Arctic 1Faroe Marine Research Institute, Nóatún 1, 100 Tórshavn, Faroe Islands
13 Dec 2010
2Danish Meteorological Institute, Lyngbyvej 100, 2100 Copenhagen Ø, Denmark
3UNI Bjerknes and Geophysical Institute, University of Bergen, Allegaten 70, 5007 Bergen, Norway
Received: 06 June 2010 – Published in Ocean Sci. Discuss.: 09 July 2010 Abstract. The flow of Atlantic water across the Greenland-Scotland Ridge (Atlantic
inflow) is critical for conditions in the Nordic Seas and Arctic Ocean by
importing heat and salt. Here, we present a decade-long series of
measurements from the Iceland-Faroe inflow branch (IF-inflow), which carries
almost half the total Atlantic inflow. The observations show no significant
trend in volume transport of Atlantic water, but temperature and salinity
increased during the observational period. On shorter time scales, the
observations show considerable variations but no statistically significant
seasonal variation is observed and even weekly averaged transport values
were consistently uni-directional from the Atlantic into the Nordic Seas.
Combining transport time-series with sea level height from satellite
altimetry and wind stress reveals that the force driving the IF-inflow
across the topographic barrier of the Ridge is mainly generated by a
pressure gradient that is due to a continuously maintained low sea level in
the Southern Nordic Seas. This implies that the relative stability of the
IF-inflow derives from the processes that lower the sea level by generating
outflow from the Nordic Seas, especially the thermohaline processes that
generate overflow. The IF-inflow is an important component of the system
coupling the Arctic region to the North Atlantic through the thermohaline
circulation, which has been predicted to weaken in the 21st century.
Our observations show no indication of weakening.
Revised: 01 December 2010 – Accepted: 06 December 2010 – Published: 13 December 2010
Citation: Hansen, B., Hátún, H., Kristiansen, R., Olsen, S. M., and Østerhus, S.: Stability and forcing of the Iceland-Faroe inflow of water, heat, and salt to the Arctic, Ocean Sci., 6, 1013-1026, doi:10.5194/os-6-1013-2010, 2010.