Tropical Pacific Drifting Buoys
Rick Lumpkin / Mayra Pazos, AOML, Miami
MAY 2010
During May 2010, 487 satellite-tracked surface drifting buoys,
75% 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 from the dateline to 100W, a broader
extent than seen in the last two months. A narrower band of
strong eastward anomalies at 4-5N, centered on 120W, persisted
from last month. Warm anomalies of +0.5C to +1.5C were common
south of the equator, while cold anomalies of -0.5C to -1.5C
were measured by several drifters north of 10N 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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