The Kuroshio Extension Observatory (KEO)
and the Role of Air-Sea Interactions in the Kuroshio Extension - by
Meghan Cronin
As PI and director of the Kuroshio Extension Observatory
(KEO), Meghan Cronin is interested in understanding the nature and effects
of the air-sea heat, moisture, momentum, and carbon dioxide fluxes in
the Kuroshio Extension region.
The Kuroshio Extension Observatory, a time series
reference site
The KEO buoy site at 32.4°N, 144.6°E is in the
recirculation gyre south of the Kuroshio Extension (Fig. 1). Funded
through NOAA Office of Climate Observations, KEO is an OceanSITES time
series reference site. It carries a full suite of sensors to monitor
air-sea exchanges of heat, moisture, momentum, and carbon dioxide, as
well as upper ocean temperature, salinity, and currents (Fig. 2). KEO
was also an element of the now-complete Kuroshio Extension System
Study. For more information on KEO, see: http://www.pmel.noaa.gov/keo/.
With funding from JAMSTEC, Dr. Hiroshi
Ichikawa and Dr. Cronin recently deployed a second surface mooring,
J-KEO, north of the Kuroshio Extension, at 37.9°N, 146.6°E (fig. 1). Ichikawa and
Cronin are respectively the Japanese and U.S. partners on the proposed "Study
of the temporal spatial variations of ocean surface fluxes in the North
Pacific using the surface mooring network".
Figure 1. The KEO (square) and J-KEO (diamond) buoys shown
in relation to the climatological wintertime NCEP2 latent heat
flux (shaded) in Wm-2 and the mean sea level height (contours).
Mean sea level heights are courtesy B. Qiu.
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Figure 2. Select measurements from the Kuroshio Extension
Observatory. Wire length of subsurface temperature are indicate
in the bottom two panels. Because the mooring has a 1.4 scope
(mooring line / water depth), the wire lengths must be combined
with pressure measurements to determine the depth of the sensors.
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The Role of Air-Sea Interactions in the Kuroshio
Extension
Cronin is presently involved in several analyses that
address:
- What is the magnitude and variability of the air-sea fluxes
in the Kuroshio Extension (KE) region? How well are these represented
in satellite products and numerical weather prediction model
forecasts and reanalyses?
- What processes give rise to anomalous air-sea fluxes?
- What processes control the SST and heat
content variations on intraseasonal-to-interannual time scales? What
controls Subtropical Mode Water formation?
- How do SST, heat content, and KE frontal variations affect
storm development, clouds, and storm path? Are these effects
enough to significantly influence the atmospheric circulation?
Figure 3. KEO surface measurements can be combined with the COARE
v3.0 bulk algorithm to estimate the latent and sensible heat fluxes,
and thus the net surface heat flux into the ocean. The oceanic frictional
velocity is computed from the wind stress, estimated using the COARE
bulk algorithm. The mixed layer depth, superimposed here on the
subsurface temperature and salinity profiles, is estimated as a
density step equivalent to .5C. The time series after May 2006 are
from the telemetered daily-averaged data.
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