ABSTRACT
Interannual Variability of Daily Extreme Precipitation Events in the
State of Sao Paulo, Brazil
Brant
Liebmann
NOAA-CIRES Climate Diagnostics Center, Boulder, Colorado
Charles Jones
Institute for Computational Earch System Science, University of
California, Santa Barbara
Leila M.V. de Carvalho
Department of Atmospheric Sciences, University of Sao Paulo, Sao Paulo, Brazil
(Manuscript received 22 October 1999, in final form 25 January 2000)
Abstract
The climatology and interannual variability of heavy, or "extreme,"
precipitation events are studied, using station data from the state of
Sao Paulo, Brazil. An extreme event is defined at each station when
daily rainfall exceeds a certain percent of its seasonal or annual
mean. It is found that these events occur mainly from November to March
and that there is a distinct interannual variation in their number. The
count of extreme events is not well correlated with mean
precipitation. The relationship between extreme events and activity in
the South Atlantic convergence zone (which, when active, is associated
with increased precipitation) is therefore not obvious. From October to
March, the interannual count of extreme events in the entire state is
correlated positively with SST anomalies in the equatorial Pacific from
near the date line to the west coast of South America. The interannual
count at stations near the Atlantic coast from November to February is
correlated positively with SST anomalies in the Atlantic Ocean near the
latitude of Sao Paulo. In both cases the relationship between SST and
mean precipitation is weak. The associations are confirmed with
composites and rank correlations. The relationships described are
apparent in the period 1976-77 to 1994-95. There is no correspondence
evident between extreme events and SST if data beginning in 1948 are
included in the analysis.