TITLE:
Atmospheric Blocking in the South Atlantic during the Summer 2014: A Synoptic Analysis of the Phenomenon
AUTHORS:
Wanderson Luiz Silva, Mariana X. Nascimento, Wallace F. Menezes
KEYWORDS:
Atmospheric Blocking, Drought, Heat Wave, South Atlantic, Southeastern Brazil, Summer 2014
JOURNAL NAME:
Atmospheric and Climate Sciences,
Vol.5 No.4,
October
9,
2015
ABSTRACT: Under
conditions of atmospheric blocking, the presence of a quasi-stationary
anticyclone of large amplitude disrupts the normal eastward progression of the
synoptic systems. These blockings correspond mainly to a positive anomaly of
the air pressure. As a result, in the regions affected by the blocking occur
several consecutive dry days and temperatures above average. This paper aims to
discuss synoptically the atmospheric blocking phenomenon occurred in January
and February 2014 in the South Atlantic Ocean, affecting especially the
Southeastern Brazil and sectors that depend on the quantity of water for their
activities in the region, such as agriculture and electricity generation. The
significant population concentration makes this area emphatically vulnerable to
long periods of drought, especially during the summer, affecting the water
supply for the population. In order to achieve this goal, data of geopotential
height at 850/500 hPa, streamlines in 850/500 hPa, pressure, temperature,
humidity and wind at surface were evaluated through NCEP/ NCAR reanalysis
(CFSRv2—Climate Forecast System Reanalysis Version 2) with 0.2° × 0.2° resolution. The analysis showed that the stationary anticyclone was configured
dynamically favorable to blocking in the lower and middle levels of the
atmosphere. Thus, atmospheric pressure at mean sea level presented values above
normal combined with high average air temperature. By the climatological
analysis, it was noted that there were emphatic negative precipitation
anomalies over Southeastern Brazil. This atmospheric blocking was characterized
as anomalous due to its long duration in a considered rainy season.