Tropical Pacific Drifting Buoys
Rick Lumpkin / Mayra Pazos, AOML, Miami
AUGUST 2011
During August 2011, 353 satellite-tracked surface drifting buoys, 57% with
subsurface drogues attached for measuring mixed layer currents, were reporting
from the tropical Pacific. Few drifters measured near-equatorial currents in
the western half of the basin. Very strong northward anomalies measured by
three near-equatorial drifters at 129W are likely associated with a tropical
instability wave. Between 140W and the date line, strong equatorial westward
anomalies of O(40 cm/s) were measured by a number of drifters between the
equator and 5S. Over much of the basin the westward SEC and NEC were stronger
than normal, with westward anomalies of 5-15 cm/s.

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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