Tropical Pacific Drifting Buoys
Rick Lumpkin / Mayra Pazos, AOML, Miami
DECEMBER 2011
During December 2011, 317 satellite-tracked surface drifting buoys, 51% with subsurface drogues attached for measuring mixed layer currents, were reporting from the tropical Pacific. Across the basin, drifters in the South Equatorial Current measured westward anomalies of O(10-20 cm/s) between the equator and 20S. Between 180-160E, these anomalies extended to 8N. Many drifters north of 10N and west of 170W measured SSTs warmer than normal by 0.5-3.0C, while drifters to the south and east measured SSTs at or slightly cooler (0-1.5C) than climatological December values. Cold anomalies were most prevalent between 20S to 20N, east of the dateline.

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 1993-2010 (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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