Anomalous patterns of SST and moisture sources in the South Atlantic Ocean associated with dry events in southeastern Brazil

Author(s)

Pampuch, Luana Albertani ; Drumond, Anita ; Gimeno, Luis ; Ambrizzi, Tercio

• Document type: Journal article
• Source: INTERNATIONAL JOURNAL OF CLIMATOLOGY; v. 36, n. 15, p. 4913-4928, DEC 2016.
• Web of Science Citations: 5

Abstract

This paper examines the distributions of anomalies of sea surface temperature (SST) and of the moisture sources in the South Atlantic Ocean during extreme dry events in southeastern Brazil in the austral autumn, winter and spring for the period 1982-2009. The extreme dry events were identified based on a combination in which consecutive dry days and variable percentiles were considered in five homogeneous regions in terms of precipitation in southeastern Brazil, as defined through cluster analysis. Composites of anomalies of SST and moisture sources for the dry events selected for the different homogeneous regions show specific characteristics for each region, but some similarities were apparent for the southern and northern parts of southeast Brazil. During spring in all regions, and during autumn and winter in the southern regions, a tripole pattern of SST anomalies was found (negative, positive and negative), together with an anomalous anticyclonic circulation in the Atlantic Ocean transporting moisture to southern Brazil associated with positive SST anomalies. A decrease in the climatological moisture sources in the south of Brazil then ensues, and dry conditions prevail in the regions of interest. In winter and autumn in the northern regions, the same tripole pattern of SST anomalies was also found, but shifted northwards. An anomalous cyclone is associated with the negative SST anomalies, and the climatological moisture sources to the northeast of Brazil reduce their contribution to the region of interest, where negative precipitation anomalies are registered. It seems that the events selected show the results of reductions both in terms of the availability of moisture and in atmospheric instability. (AU)

• FAPESP's process: 11/08191-4 - Synoptic and Dynamics Features of Extreme Dry Periods on the Southeast of Brazil and its Relation to the South Atlantic SST
• Grantee: Luana Albertani Pampuch Bortolozo
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 12/14316-7 - Dynamics and synoptic characteristics of extreme dry periods over the Southeast of Brazil and its relation to the South Atlantic SST - characterization of dry extreme events and simulations with climate models in IPCC scenarios
• Grantee: Luana Albertani Pampuch Bortolozo
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• 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
• FAPESP's process: 08/57719-9 - Program on Climate Change - INCT CLIMA
• Grantee: Carlos Afonso Nobre
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants