On the possibility of barotropic instability over northeast Brazil

Abstract
The easterly zonal wind profile over northeast Brazil during the rainy season of a heavy rainfall year satisfies the necessary condition for the existence of barotropic instability. The wave with a wavelength of 1250 km has the highest growth rate, 1.6 times 10-6 s-1 (e—folding time of about 6 days). The zonal wind profile is found to be stable during a dry year. This suggests that it is likely that barotropic instability might contribute to the interannual variations of rainfall over northeast Brazil. DOI: 10.1111/j.1600-0870.1984.tb00240.x