The relationship between the Antarctic oscillation and blocking events over the South Pacific and Atlantic Oceans

Autor(es)

Damiao Mendes, Monica Cristina ^[1] ; Albuquerque Cavalcanti, Iracema Fonseca ^[1]

Afiliação do(s) autor(es)

^[1] Natl Inst Space Res CPTEC INPE, Ctr Weather Forecasting & Climate Studies, Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: INTERNATIONAL JOURNAL OF CLIMATOLOGY; v. 34, n. 3, p. 529-544, MAR 15 2014.
• Citações Web of Science: 9

Resumo

It is known that blocking events have impacts on the behaviour of transient systems and affect the weather in southern continental regions of the Southern Hemisphere. Since the main mode of variability in Southern Hemisphere, the annular mode, or Antarctic Oscillation (AAO), changes the extratropical atmospheric circulation, the blocking characteristics over Pacific and Atlantic Oceans are analysed in this study, in terms of the two opposing phases of the AAO. The characteristics of atmospheric flow patterns and blocking events are analysed as a function of season during the period 1979-2000. The relative frequency of blocked days is different for each AAO phase. Maximum duration and number of events over the Southwestern Pacific and South Atlantic regions occur in the positive phase, while the blocking activity over the Southeastern Pacific region is similar in the two phases but the persistence is higher in the negative phase. The atmospheric anomalous centres associated with middle latitude and polar AAO signals, as well as the behaviour of subtropical and polar jets are discussed in relation to the blocking characteristics. Convection over South America is analysed for blocking periods in each AAO phase and is discussed based on anomalous circulation in each phase. Wavetrain patterns over the South Pacific and variations in intensity of jet streams induce anomalous circulation over South America, which are associated with the track and persistence of transient systems over Southeastern South America and with convection over the continent. (AU)

• Processo FAPESP: 08/53662-2 - Influência da oscilação antártica sobre os bloqueios atmosféricos e perspectiva para os cenários futuros
• Beneficiário: Monica Cristina Damiao Mendes
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado