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Tropical Pacific Drifting Buoys
Rick Lumpkin / Mayra Pazos, AOML, Miami
JANUARY 2010
During January 2010, 426 satellite-tracked surface drifting buoys,
86% with subsurface drogues attached for measuring mixed layer currents,
were reporting from the tropical Pacific. The dramatic basinwide El
Nino-related eastward anomalies seen in the last few months had become
less prominent in January. West of the dateline, near-equatorial drifters
exhibited eastward anomalies of ~50 cm/s, moving eastward where the
climatological January current is westward, while several drifters in the
longitude band 140-160W exhibited 20-40 cm/s westward anomalies. Elsewhere,
currents were near their climatological average, although they indicated
that the NECC was shifted two degrees south of its normal position across a
broad stretch of the basin. Hot equatorial SST anomalies of +0.5 to +3.0C
were measured by most drifters in the region 100W-170E, 20S-10N. Cold SST
anomalies (-0.5 to -3.0C) were observed in the southeastern corner of the
basin as in previous months.

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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