D. Roemmich et J. Gilson, Eddy transport of heat and thermocline waters in the North Pacific: A key to interannual/decadal climate variability?, J PHYS OCEA, 31(3), 2001, pp. 675-687
High-resolution XBT transects in the North Pacific Ocean, at an average lat
itude of 22 degreesN, are analyzed together with TOPEX/Poseidon altimetric
data to determine the structure and transport characteristics of the mesosc
ale eddy field. Based on anomalies in dynamic height, 410 eddies are identi
fied in 30 transects from 1991 to 1999, including eddies seen in multiple t
ransects over a year or longer. Their wavelength is typically 500 km, with
peak-to-trough temperature difference of 2.2 degreesC in the center of the
thermocline. The features slant westward with decreasing depth, by 0.8 degr
ees of longitude on average from 400 m up to the sea surface. This tilt pro
duces a depth-varying velocity/temperature correlation and hence a vertical
meridional overturning circulation. In the mean, 3.9 Sv (Sv equivalent to
10(6) m(3) s(-1)) of thermocline waters are carried southward by the eddy f
ield over the width of the basin, balanced mainly by northward flow in the
surface layer. Corresponding northward heat transport is 0.086 +/- 0.012 pW
. The eddy field has considerable variability on seasonal to interannual ti
mescales. For the 8-yr period studied here, eddy variability was the domina
nt mechanism for interannual change in the equatorward transport of thermoc
line waters, suggesting a potentially important forcing mechanism in the co
upled air-sea climate system.