Abstract
Active mesoscale (300 km diameter) eddy formation off the Pacific coast of Central America was observed during February 1976 by a thermal infrared sensor aboard the NOAA 4 satellite. These anticyclonic eddies, closely associated with wind-induced upwellings, propagate westward at an average speed of 13 km day−1, which is approximately the speed of nondispersive baroclinic Rossby waves at latitude 12°N.