Mode
water formation and boundary layer dynamics - by
Roger Samelson
Roger is interested in the ocean
and atmosphere processes that lead to mode water formation (e.g.,
Dewar et al., 2005) and the coupled boundary layer dynamics of the
ocean and atmosphere and its representation in models (e.g., Samelson
et al., 2006; Skyllingstad et al., 2006; Chelton et al., accepted;
Perlin et al., accepted). Recent
high-resolution coupled modeling has shown that air-sea coupling can
change surface stress by 50% in 72 hours in coastal regions, through
the influence of variable SST on the atmospheric boundary layer (see
attached figure, from Perlin et al). He hopes that the working
group can stimulate extensions of the work of, for example, Maloney
and Chelton (2006), that will focus in more detail on the air-sea interaction
processes in the western boundary current and mode water formation regions,
and their representation in models, and which will be informed by in-situ
measurements as well as remote-sensing data. Important basic questions
that he believes are open include:
-
How do the ocean and atmosphere boundary
layers interact during mode water formation, and what processes
must be resolved to model this interaction adequately?
-
How does this boundary layer interaction
affect larger-scale circulation and variability in the ocean
and the atmosphere?
-
Do large-scale ocean dynamical or regional
air-sea interaction processes dominate mode-water formation,
and what is the dependence of their relative influence on timescale?
Figure 1 (a-b). Atmospheric surface focing
variables in the end of 72-h run for three simulations: a) surface meridional
wind stress from the atmospheric model, b) downward surfacenet heat
flux (positive downward). Note that this model time corresponds to 0400
LST, and therefore solar radiation is zero at that time. Negative net
heat fluxes into the ocean correspond to heat loss by the ocean and
thus unstable conditions in general.
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