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Subtropical South America

Hydroclimate of subtropical South America

The La Plata basin of subtropical South America—encompassing parts of Brazil, Bolivia, Paraguay, Argentina, and Uruguay—experiences frequent occurrences of large, organized thunderstorm complexes during the warm season. These “mesoscale convective systems” provide much of the region’s precipitation and can also produce hazards such as flooding, hail, strong winds, and tornadoes. My colleagues and I have found that the development of these thunderstorm complexes is favored by moisture advection from the Amazon and the South Atlantic Ocean. We have also described an out-of-phase relationship between organized convection over the La Plata basin and precipitation in the South Atlantic Convergence Zone of coastal Brazil, with implications for water supplies in the region’s major population centers.

Mesoscale convective system example
Lower-tropospheric (left) and upper-tropospheric (right) conditions during example mesoscale convective system (top) and South Atlantic Convergence Zone (bottom) events.
From Mattingly and Mote 2017, Climate Dynamics. Reprinted by permission from Springer Nature, Copyright 2017.

 

Southern Brazil MCS conditions
Lower-tropospheric conditions (850 hPa wind and relative humidity, 1000–700 hPa integrated water vapor transport) for mesoscale convective systems in southern Brazil. Left panel shows events associated with the first principal component of 850 hPa geopotential height, right panel shows second principal component events.
From Moraes et al. 2020, Climate Research. Reproduced by permission of Inter-Research, © Inter-Research 2020

 

Read more:

  • Mattingly and Mote, 2017 (Climate Dynamics): Variability in warm-season atmospheric circulation and precipitation patterns over subtropical South America: relationships between the South Atlantic Convergence Zone and large-scale organized convection over the La Plata basin
  • Moraes et al., 2020 (Climate Research): Atmospheric characteristics favorable to the development of Mesoscale Convective Complexes in southern Brazil