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In recent years the oceanographic community has gained
access to information that constitutes a formidable leap
for our science. This information includes data from
remote sensing instruments such as satellite altimetry and
ice thickness from upward looking sonar, in situ
observations like hydrography from SeaSoar-CTD and current
measurements from VM-ADCP, and model simulations of the
ocean circulation that produce results with an increasing
level of details. The expression "high resolution
information" is here used as a reference to the joint sets
of information just listed. In Task 5, we seek to take
advantage of these advances in order to arrive at an
enhanced understanding and improved description of
processes relevant to the ocean climate of the Nordic Seas
and the Arctic Sea. The work planned for Task 5 includes
studies of
(1): variability in the transports of the northern
branches of the Gulf Stream system due to oceanic
teleconnections by signal propagation
(2): variability in the fluxes and paths of Atlantic Water
that enters the Nordic Seas
(3): variability related to the front between Atlantic
Water and Arctic Water in the Nordic Seas
(4): variability and trends related to the ice cover and
ice transport in the Arctic Sea and Nordic Seas
In Norway, little attention has so far been paid to
examine and understand how the variability of the regional
circulation is affected by the variability of the North
Atlantic ocean circulation. Hence, one goal is to
investigate the relations between anomalous events in the
North Atlantic Ocean and variability of the flux of
Atlantic Water into the Nordic Seas. The lengths of the
available time series from the sets of high resolution
information fall short of the period required for studying
decadal variability. Hence, we will use these sets in a
study of seasonal and interannual variability and episodic
events during the last 10-20 years.
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The inflow of Atlantic Water (AW) to the Nordic Seas may
be considered as being divided between two pathways, an
eastern branch and a western branch. Flow along the two
pathways may differ both in the characteristics of the
water masses as they enter the Nordic Seas, and in the
modifications of AW by mixing with adjacent water masses
while in the Nordic Seas. We will describe and analyze to
what degree the variability is forced by oceanic
teleconnections through signal propagation, and local
atmospheric forcing. Particular attention will be paid to
the period 1992-present, for which simulation results,
high quality altimeter data, data from hydrography
crossections, and current measurements are all
available. Further, we will address the question of
whether the widely different AW transport values that has
been reported are related to oceanic variability or
observational inaccuracies, or a combination of the two.
Trends in the ice coverage of the Arctic Ocean is
recognized as being an important indicator of climate
change in Norteast Europe and other regions. Also, sea ice
is by itself important for the climate, since there is a
strong feedback in the heat fluxes between the atmosphere
and ocean related to melting and freezing of ice. We will
take advantage of the relevant high quality information
that has been made available in the recent years from,
e.g., upward-looking sonar, passive microwave data, and
model simulations. Results may provide clues about
relations between variability of AW and variability
related to Arctic sea ice and hydrography due to signal
propagation. The interannual variability of the ice
thickness will be given particular attention, and results
should prove valuable in order to sort out the widely
different trends that have been reported in the
literature.
Variability in the AW inflow to the Nordic Seas and
variability in the East Greenland Current related to
events in the Arctic Ocean have the potential for strongly
influencing processes in the frontal zone between these
water masses in the Nordic Seas. Obviously, the local
winds are also important in this context. A process study
of the mixing of water masses across this front will be
undertaken in a separate task (Principle Task 4). Here, we
aim at describing the seasonal and interannual variability
of the position and strength of this front. Again, the
work will be performed using a combination of
observational data and model results.
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