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Tropical Pacific Drifting Buoys
Rick Lumpkin / Mayra Pazos, AOML, Miami
SEPTEMBER 2008
During September 2008, 353 satellite-tracked surface drifting buoys, 85% with
subsurface drogues attached for measuring mixed layer currents, were reporting
from the tropical Pacific. Westward anomalies of 10-20 cm/s were measured by
several drifters in the SEC at 140-180W, 2-8S. A few drifters in the eastern
NECC revealed eastward anomalies of 20 cm/s, but the robustness of this is unclear.
Elsewhere, currents were near their climatological September strength. Across
most of the basin, SSTs were near or slightly cooler than their typical September
values, with cold anomalies of -0.5 to -1.5C most common between 140W and the
dateline. Warm anomalies of +0.5 to +3.0C were measured by many drifters in the
northwest corner of the basin (west of 180, north of 10N) as seen last month.

FIGURE A1.1
a) Top: Movements of drifting buoys in the tropical Pacific Ocean.
The linear segments of each trajectory represent a one week displacement.
Trajectories of buoys which have lost their subsurface drogues are gray; those with
drogues are blue.
b) Middle: Monthly mean currents calculated from all buoys 1993-2002 (gray),
and currents measured by the drogued buoys this month (black) smoothed by an
optimal filter.
c) Bottom: Anomalies from the climatological monthly mean currents for this month.
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