Mechanisms of Meteorological Drought over São Paulo, Brazil
Abstract
Seasonal variability in precipitation leading to drought, can have severe impact on agriculture, tourism, energy, and water resource sectors with considerable negative consequences to human welfare and the economy. Located between latitude 20º and 25º S and longitude 53º and 45º W in southeastern Brazil, São Paulo state is highly vulnerable to seasonal variability in climatic variables impacting weather and climate. This study examines the large-scale mechanisms associated with the characteristics of meteorological drought over São Paulo. We characterizes drought episodes over São Paulo by the 10 lowest mean annual precipitation time series during the period 1950 - 2010 using the Climatic Research Unit precipitation dataset. The circulation patterns associated with meteorological drought are analyzed using the large-scale fields from the ERA-20C output. The preliminary results of the observed analysis showed that dry years arise from several dry seasons with precipitation deficits during DJF most important (46%) but SON (24%) and MAM (20%) also significant. The ERA-20C composite of large-scale patterns associated with droughts showed that drought events over São Paulo is a result of an interplay between mid-level geopotential height anomaly and eastward displayed wind circulation coupled with reduced moisture content in the atmospheric column over the source region. The study also examines if HadGEM3-GA6-N96 model simulations reproduce the observed drought mechanisms. The model gives a realistic simulation of the 500-hPa geopotential height but with a slightly larger magnitude than in ERA-20C. The future analysis will focus on attribution of changing drought risk for southeast Brazil.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMGC21E1152A
- Keywords:
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- 1616 Climate variability;
- GLOBAL CHANGEDE: 1620 Climate dynamics;
- GLOBAL CHANGEDE: 1630 Impacts of global change;
- GLOBAL CHANGEDE: 4313 Extreme events;
- NATURAL HAZARDS