Post-summer heavy rainfall events in southeast Brazil associated with south Atlantic convergence zone

Abstract

Heavy rainfall events (HREs) in the post-summer month of March in Southeast Brazil cause disasters such as floods, mudslides and landslides, mainly because the soil becomes saturated by February. Forty-five years of rainfall data show that heavy rainfall frequency increases again in the month of March. The composite anomaly fields of the atmospheric circulation during and before HREs associated with the formation of South Atlantic Convergence Zone show some special characteristics that may be used as a guide for early warning. The convergence of moisture flux in the troposphere over the region grows 40% during the 48 h before the HRE in March. Copyright © 2010 Royal Meteorological Society.