Summer dry events on synoptic and intraseasonal timescales in the Southeast Region of Brazil

Autor(es)

Anderson Augusto Bier ^[1] ; Simone Erotildes Teleginski Ferraz ^[2] ; Tercio Ambrizzi ^[3]

Afiliação do(s) autor(es)

^[1] Universidade de São Paulo - Brasil

^[2] Universidade Federal de Santa Maria - Brasil

^[3] Universidade de São Paulo - Brasil

• Tipo de documento: Artigo Científico
• Fonte: ATMOSFERA; v. 36, n. 1, p. 57-76, 2022-11-07.

Resumo

ABSTRACT The occurrence of dry events in the Southeast Region of Brazil (SEB) during summer (rainfall season) has been in evidence in the last years, mainly due to previous extreme events in the 2013/14 and 2014/15 seasons. Drought analyses are usually carried out with monthly data. Here our methodology addresses the issue with daily data to generate a thorough analysis. Dry events were evaluated in different homogeneous precipitation sub-regions within the SEB, over 37 December-February (DJF) seasons and with two different timescales of duration: synoptic (5-9 days) and intraseasonal (≥10 days). Two main distinct dynamic patterns were found for dry events in southern and central-northern parts of SEB, respectively, but no significant differences were identified in the different timescales of occurrence. Southern events were characterized by a stationary ridge acting over the whole of southern South America, making the approximation of the transient system to southern SEB difficult. At the same time, this pattern showed a northern-shifted South Atlantic Convergence Zone (SACZ) configuration. In the central-northern events, a high pressure centered between Brazil’s South and Southeast regions was associated with the dryness conditions. An anomalous southward shift of meteorological systems characteristic of the South American summer was also verified for these events. Over the South Atlantic, an opposite SST anomaly configuration was identified between southern and central-northern events. (AU)

• Processo FAPESP: 18/06806-0 - Alterações nos modos de variabilidade do Oceano Atlântico Sul e impactos sobre o clima da América do Sul sob o aspecto de mudanças climáticas
• Beneficiário: Anderson Augusto Bier
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 17/09659-6 - Variabilidade interanual dos transportes meridionais através da rede transatlântica SAMOC (SAMBAR)
• Beneficiário: Edmo José Dias Campos
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 14/50848-9 - INCT 2014: INCT para Mudanças Climáticas (INCT-MC)
• Beneficiário: Jose Antonio Marengo Orsini
• Modalidade de apoio: Auxílio à Pesquisa - Programa de Pesquisa sobre Mudanças Climáticas Globais - Temático