Extreme precipitation events and their relationship with ENSO and MJO phases over northern South America

Author(s)

Shimizu, Marilia Harumi ; Ambrizzi, Tercio ; Liebmann, Brant

• Document type: Journal article
• Source: INTERNATIONAL JOURNAL OF CLIMATOLOGY; v. 37, n. 6, p. 2977-2989, MAY 2017.
• Web of Science Citations: 16

Abstract

Several droughts and floods in Amazonia and Northeast Brazil have occurred in recent years and projections from Intergovernmental Panel on Climate Change indicate an increase of these extreme events. El Nino Southern Oscillation (ENSO) is one of the phenomena associated with extreme rainfall events in the Amazon. However, recent studies have indicated that the basic response of ENSO is dependent on the Madden-(Julian Oscillation (MJO) phase. Hence, this study analyses the MJO influence on precipitation extreme events over northern South America in El Nino and La Nina years. Extreme precipitation events over northern South America for the rainy season (December-(May) were obtained through a composite analysis of the combinations of ENSO and MJO phases. Most of the dry extreme events occurred during El Nino periods, while wet extreme events were more recurrent during La Nina or neutral years. However, the results showed that the MJO convection could enhance or weaken the basic response of ENSO on extreme precipitation events. Moreover, dry/wet extreme events over both Amazon and Northeast Brazil are favoured when MJO convection over Indonesia is enhanced (MJO phases 4 and 5)/suppressed (MJO phase 2). Additionally, the interannual variability of the extreme events showed an increasing linear trend for dry extreme events and a decreasing linear trend for wet extreme events. The results presented here contribute to a better understanding of the climate variability and will be helpful for the forecast of ENSO effects on extreme events over northern South America. (AU)

• FAPESP's process: 13/50521-7 - Multi-scale processes driving tropical convection and influence of the aerosol
• Grantee: Tercio Ambrizzi
• Support Opportunities: Research Program on Global Climate Change - Regular Grants
• FAPESP's process: 13/02797-3 - Analysis of the combined effects of El Niño Southern Oscillation and Madden-Julian Oscillation phases on extreme precipitation and temperature events
• Grantee: Marilia Harumi Shimizu
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 08/58101-9 - Impact of the Southwestern Atlantic Ocean on South American climate for the 20th and 21st centuries
• Grantee: Tercio Ambrizzi
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants