Tropical Pacific Drifting Buoys
Rick Lumpkin / Mayra Pazos, AOML, Miami
FEBRUARY 2010
During February 2010, 439 satellite-tracked surface drifting buoys, 87%
with subsurface drogues attached for measuring mixed layer currents, were
reporting from the tropical Pacific. The dramatic El Nino-related eastward
anomalies seen in the last several months persisted in February.
Near-equatorial drifters between the dateline and 160W exhibited eastward
anomalies of 30-50 cm/s. Several drifters in the longitude band 140-160W
exhibited 20-40 cm/s westward anomalies, with the strongest anomalies measured
by a cluster of drifters located between 6S and the equator. Weaker eastward
equatorial anomalies were present from 130-160W. Elsewhere, currents were near
their climatological average. Across much of the basin, SSTs were close to their
climatological February values. Cold SST anomalies (-0.5 to -1.5C) were observed
by most drifters in the southeastern corner of the basin, as seen 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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