Concurrent altimeter and infrared observations of Rossby wave propagation near 34 degrees N in the Northeast Atlantic

We present observations of long-wavelength baroclinic Rossby waves near 34 degrees N in the Northeast Atlantic ocean (east of the Mid-Atlantic Ridge) using both TOPEX/POSEIDON sea surface height (SSH) altimeter data and ERS-1 Along-Track Scanning Radiometer sea surface temperature (SST) measurements. Using the Fourier transforms of longitude-time diagrams of the zonal gradients of SST and SSH we locate the spectral components corresponding to westward wave propagation and estimate wavelength, period and propagation speed. The energy associated with the propagating waves in that region is distinctly higher than in the surrounding areas. The similarities between the properties of the SST and SSH zonal gradients are remarkable with the same propagating signals clearly observed in both fields. It is believed that the interaction between the Rossby waves and the Azores current could play a major role in the amplification of the waves themselves.