An array of current meter moorings along 12 degrees W on the southern
side of the Iceland-Faeroe Ridge reveals a narrowband barotropic oscil
lation with period 1.8 days in spectra of velocity. The signal is cohe
rent over at least 55-km scales and propagates phase with shallow wate
r on the right (toward the northwest). Velocity ellipses tend to be el
ongated (crossing contours of f/H) and rotate anticyclonically. Soluti
ons of the rigid-lid barotropic shallow-water equations predict the oc
currence of a topographic-Rossby normal mode on the south side of the
ridge with spatial Scales exceeding 250 km and with intrinsic period n
ear 1.84 days. This fundamental mode of the south side of the ridge ha
s predicted spatial structure, phase propagation, and velocity ellipse
s consistent with the observed oscillation. The frictional amplitude e
-folding decay time for this normal mode is estimated from the observa
tions to be 13 days. The observed ocean currents are significantly coh
erent with zonal wind stress fluctuations (but not with wind stress cu
rl) in the relevant period band, which indicates the oscillation is wi
nd forced. This appears to be the first clear evidence of a stochastic
ally forced resonant barotropic topographic-Rossby normal mode in the
ocean.