Impacts of the Madden‐Julian Oscillation on the intensity and spatial extent of heavy precipitation events in northern Northeast Brazil

• Published in: International journal of climatology 2021-05, Vol.41 (6), p.3628-3639
• Main Authors: Vasconcelos Junior, Francisco das Chagas, Jones, Charles, Gandu, Adilson W., Martins, Eduardo Sávio P. R.
• Format: Article
• Language: English
• Subjects: Anomalies; Atmospheric circulation; Atmospheric precipitations; extreme rainfall; Extreme weather; Heavy precipitation; Heavy rainfall analysis; Life cycle; Life cycles; Madden-Julian oscillation; MJO life cycle; Northeast Brazil; Phases; Planetary waves; Precipitation; Precipitation systems; Propagation; Rain; Rainfall; Rainfall forecasting; Rainy season; Rossby wave propagation; Rossby waves; Seasons; Spatial analysis; Teleconnections; Tropical climate; Water circulation; Water vapor; Water vapour; Wave propagation; Wet season
• ISSN: 0899-8418; 1097-0088
• DOI: 10.1002/joc.7039

This paper investigates the spatiotemporal variability of Contiguous Extreme Precipitation Events (CEPE) related to Madden‐Julian Oscillation (MJO) activity during the pre‐wet season and wet season in northern Northeast Brazil for 30 years (1979–2010). Inherent differences in rainy season regimes are associated with northern Northeast Brazil precipitation systems; these are isolated during pre‐wet and wet season and analyse the intensity and the spatial area covered by the CEPE. A daily index of MJO activity and its life cycle were used to identify activity phases during heavy rainfall events. Composite analysis was performed for days with CEPE during the most frequent MJO phases in the pre‐wet and wet seasons. The analysis shows the influence of the MJO on the occurrence of CEPE in northern Northeast Brazil. In the pre‐wet season, the MJO phases 8‐1‐2 affect the occurrence of heavy rainfall events, modifying the atmospheric circulation and water vapour transport over northern South America. Indications of Rossby wave propagation over the South Pacific associated with MJO were found, suggesting tropic‐extratropic teleconnection during occurrences of CEPE in the pre‐wet season. In the wet season, CEPE events are more frequent during MJO phases 8‐2‐3. Conversely, no wave propagation over the South Pacific is observed in the wet season, changes in wind anomalies at high and low atmospheric levels only point to the influence of the MJO via tropical teleconnection. This study may help monitoring and forecasting of very heavy rainfall events in northern Northeast Brazil in pre‐wet season and wet season. The intensity and extent of extreme rainfall events in northern Northeast Brazil show sensitivity to the Madden‐Julian Oscillation (MJO) lifecycle. The MJO mechanism intensifies the occurrence of very heavy rainfall events in northern Northeast Brazil during the pre‐wet season and wet season. In the pre‐wet season, the extreme events are marked by Rossby wave‐like propagation in the South Pacific.