Tropical Pacific Drifting Buoys
Rick Lumpkin / Mayra Pazos, AOML, Miami
APRIL 2008
During April 2008, 308 satellite-tracked surface drifting buoys, 80% with subsurface drogues
attached for measuring mixed layer currents, were reporting from the tropical Pacific.
The westward anomalies over most of the basin, seen in the previous several months, persisted
in April. Strong (20-30 cm/s) eastward anomalies were measured by several near-equatorial
drifters at 140-150W. Cold SST anomalies (-0.5 to -3.0C) were measured by many drifters in
the central Pacific (140W to the dateline), while warm anomalies (+0.5 to +1.5C) were measured
in the southeast, southwest and northwest edges of the tropical Pacific basin.

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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