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In order to analyze the available information, we will use
a variety of statistical methods. The information can
generally be divided into three categories, (1) horizontal
fields, (2) crossections, and (3) vertical
transects. Moreover, all information is available as
functions of time, albeit for different durations.
The horizontal fields are of particular interest when it
comes to detection of signal propagation. We intend to use
various fairly simple statistical methods to this
end. First, we need to determine the paths of
anomalies. We will apply complex empirical orthogonal
functions (complex EOFs), which have the advantage of
capability of tracking propagating spatial patterns
(compared to ordinary EOFs). If deemed necessary, these
analyses will be supplemented by multi-channel singular
spectrum analysis. We will also consider the pathways of
the main ocean currents, and reported anomaly
pathways. Another alternative is to objectively determine
these pathways from boxed budgets by looking for anomalous
events at the various box edges. Results will be
supplemented by visual detection from computer animations.
Once their pathways have been described, anomalies will be
tracked and described using techniques such as Hovmøller
diagrams and computation of lagged correlations. We will
study results from crossections, including extracted
pathways, using EOF analysis, and possibly other related
techniques such as analysis by Principal Oscillation
Patterns.
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Information from the fields will be extracted along the
crossections where data are available. In addition to the
obvious purpose of a general intercomparison, these
complementary sets will be used in order to evaluate the
applicability of the data that are only available as
crossections with respect to investigations of seasonal
and interannual variability.
Horizontal fields in the Arctic ocean will also be
investigated for trends. For this purpose, time series
analysis of results from spatial integration of the
relevant properties will be performed. These results will
predominantly be obtained for the subdomain(s) of the
fields.
To a certain extent, analyses of the ocean and ice
circulation features which have been described this far
will be supplemented by analysis of processes occurring at
the ocean-(ice-)atmosphere interface. Here, we will
describe how the fluxes of momentum, heat and/or fresh
water across this interface contribute to variability on
the timescales in question. These analyses are best
performed for horizontal fields, whereas for, e.g.,
crossections, such analyses are contaminated by advective
processes.
All methods have been selected because they are
well-suited for the task work that is described
above. Moreover, all analyses are defined based on this
task's objectives and the relevant overall objectives of
the coordinated project.
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