On the monsoons of South America Part 2 : Interaction with extratropical disturbances and formation of tropical depressions and upper-tropospheric cyclonic vortices

Abstract

The paper reveals a stationary wave structure of the heat low circulation over South America during the southern summer and discusses how the stationary wave may interact with eastward-propagating extratropical disturbances of the two hemispheres. The interactions appear to explain several observed features of the continent’s weather and climate. In particular, they appear to lead to formation of westward-propagating tropical disturbances, such as  monsoon lows and depressions and upper-tropospheric cyclonic vortices. The origin, structure, development and movement of these disturbances are discussed. The paper also looks into the nature and structure of the South Atlantic Convergence Zone (SACZ) and discusses its interaction with the extratropical disturbances of the southern hemisphere.