15 Interrelationship between interannual extremes of Antarctic sea ice and atmospheric blocking on the Southeast Pacific and Southwest Atlantic

Tuesday, 30 April 2013
North/West Room (Renaissance Seattle Hotel)
Camila Bertoletti Carpenedo, Institute of Astronomy, Geophysics and Atmospheric Sciences/Univ. of São Paulo, São Paulo, Brazil; and T. Ambrizzi

South America has an economy highly dependent on agriculture. The close link between agricultural production and weather conditions, particularly extreme weather events, at producing regions have highly damaging effects. Among these phenomena, atmospheric blockings are highlighted, because their persistent and systematic nature, affecting the normal propagation of transients systems and consequently the weather and climate in some continental regions through adverse weather conditions. Therefore, a better understanding of the mechanisms which cause, keeps and dissipate this phenomenon are of great importance for the successful prediction of short, medium and long term weather and climate. The blocking events in the Southern Hemisphere mainly occur between latitudes 50° and 65° S and during the winter and spring months, exactly at the period of higher extent of Antarctic sea ice, which reaches latitudes around 55° S in the Indian Ocean region during September. It should be emphasized that the sea ice plays an important role in the variability and regional and global climatic conditions through dynamic and thermodynamic processes, and feedback mechanisms. In this sense, interactions between the Antarctic sea ice and atmospheric blockings in the Southern Hemisphere probably exist, although little is known about such relationships. The objective of this study is to understand the differences associated with the frequency, location and duration of blocking events in the Southeast Pacific and Southwest Atlantic in positive and negative extremes of Antarctic sea ice. Furthermore, we intend to examine how the regions of occurrence of blocking are related to the different sectors of sea ice cover. We used surface and atmospheric fields from the ERA-Interim reanalysis, obtained from the European Centre for Medium-Range Weather Forecasts (ECMWF) Data Server. The sea ice coverage was obtained from NOAA/OAR/PSD Earth System Research Laboratory. For both data sets, the series are for the period between 1982 and 2012.
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