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Tropical Pacific Drifting Buoys
Rick Lumpkin / Mayra Pazos, AOML, Miami
JUNE 2009
During June 2009, 355 satellite-tracked surface drifting buoys,
72% with subsurface drogues attached for measuring mixed layer
currents, were reporting from the tropical Pacific. North of
10S, eastward anomalies have intensified since last month, with
magnitudes of 10-20 cm/s now seen across the basin. In the narrow
band of the NECC at 10N, weak westward anomalies were measured by
several drifters. From 10-22S, westward anomalies of O(10 cm/s)
were common across the basin. Most drifters away from the northwest
corner of the region measured SST at or above normal June values,
with anomalies of +0.5 to +1.5C very common. Warm anomalies were
especially prevalent in the southeast tropical Pacific. Cold
anomalies (-0.5C to -3.0C) were measured by many drifters in the
northwest, north of 20N and west of the dateline. These SST anomaly
patterns have persisted over the previous several 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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