Tropical Pacific Drifting Buoys
Rick Lumpkin / Mayra Pazos, AOML, Miami
During June 2007, 346 satellite-tracked surface drifting buoys, 68% with
subsurface drogues attached for measuring mixed layer currents, were
reporting from the tropical Pacific. Strong (~30 cm/s) westward
anomalies were measured by a large number of drifters at 5-10N, 150W to
150E, a broader region than seen last month. Weaker westward anomalies
of 10-20 cm/s were exhibited across the basin, from 20N to 20S, by much
of the array. Five drifters at 6-8N, 130-136W exhibited eastward
anomalies associated with advection at the northern edge of the
instability wave train. As in May, most drifters north of the equator
and east of the dateline measured SSTs near normal seasonal values,
although many exhibiting westward current anomalies also measured SSTs
colder by -0.5 to -1.5C. South of the equator and west of 130W, the
majority of drifters measured SSTs of +0.5 to +1.5C above typical June
values.
Top:Movements of drifting buoys in the tropical Pacific Ocean during jun07.
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 black.
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.
Bottom: Anomalies from the climatological monthly mean currents for this month.