Tropical Pacific Drifting Buoys
Rick Lumpkin / Mayra Pazos, AOML, Miami
APRIL 2010
During April 2010, 459 satellite-tracked surface drifting buoys, 73% with
subsurface drogues attached for measuring mixed layer currents, were reporting
from the tropical Pacific. Dramatic 50 cm/s westward anomalies were measured
by many near-equatorial drifters at longitudes 110-150W, somewhat east of the
weaker anomalies seen last month. A narrower band of eastward anomalies was
measured at 4-5N, centered on 120W. Warm anomalies of +0.5C to +1.5C were common
south of 10N, while cold anomalies of -0.5C to -1.5C were measured by several
drifters north of this and west of 140W.

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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