Tropical Pacific Drifting Buoys
Rick Lumpkin / Mayra Pazos, AOML, Miami
MAY 2008
During May 2008, 325 satellite-tracked surface drifting buoys, 81% 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, weakened
in May. Strong (20-30 cm/s) eastward anomalies were measured by some near-equatorial drifters
at 120-140W, east of where eastward anomalies were observed in April. Cold SST anomalies
(-0.5 to -3.0C) were measured by most drifters in the central Pacific (170E to the 130W) at
5N to 15N, while warm anomalies (+0.5 to +1.5C) were measured in the southeastern and southern
(below 10S) 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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