Copyright © The Oceanographic Society of Japan. Zonal Wavelengths of Planetary Rossby Waves Derived from Hydrographic Transects in the Northeast Atlantic Ocean?

Using hydrographic data of three extended zonal sections, which cover the upper 1000 dbar layer along 10°, 21°, and 32°N in the North-East Atlantic between 20 ° and 45°W, observational evidence is presented for zonal wavelengths of resonantly excited, first mode, long, baroclinic Rossby waves. The amplitudes of associated anomalies in the mass field decrease with increasing offshore distance. The associated zonal wavelengths reach several hundred kilometres and decrease with increasing latitude. Due to the Rossby dispersion, the detected wave patterns slowly propagate westward, somewhat faster in the south than in the north. The results obtained confirm the data sets re-motely sensed by satellites, as well as the outcomes of analytical and numerical mod-els. by Cipollini et al. (1997) and Polito and Liu (2003), mainly reflect the properties of free waves. Power spec-trum analyses of current measurements at nominal depths between 250 m and 1165 m, which were conducted for more than seven years north-west of the Canary Island