Impact of Atmospheric Blocking on Extremes in South America and the South Atlantic

Event type: 
14 February 2018
2.00 - 3.00pm

Climate Change Research Centre, Seminar Room, Mathews Building 4th floor, UNSW, Sydney

Regina Rodrigues
Department of Geosciences, Federal University of Santa Catarina, Florianópolis, Brazil
Climate Change Research Centre, UNSW, Australia

Atmospheric blocking over east subtropical South America (SSA) in austral summer can prevent the establishment of the South Atlantic Convergence Zone (SACZ). As such, years with more blocking days coincide with years with fewer SACZ days and reduced precipitation. We find that MJO is a key source of long-term variability in SSA blocking frequency. Blocking events lead to extremes of surface temperature and precipitation over SSA. Up to 80% of warm surface air temperature extremes occur simultaneously with SSA blocking events. The worst droughts in southeast Brazil, during the summers of 1984, 2001 and 2014, are linked to record high numbers of SSA blocking days. Moreover, by decreasing cloud cover associated with the absence of the SACZ, blocking events enhance the heat flux into the ocean causing marine heatwaves in the western subtropical South Atlantic.

Speaker biography: Regina is an Associate Professor in Physical Oceanography at the Federal University of Santa Catarina in Brazil. She coordinates the Subsection on Extreme Events of the Brazilian Network for Climate Change. Her research focuses on the large-scale physical processes of the tropical and South Atlantic, and their impacts on the climate of South America and Africa.