Abstract
Previous study showed that the interaction of synoptic disturbances with intraseasonal anomalies is important for heavy rainfall in the South Atlantic Convergence Zone and the La Plata basin during the austral summer. Here, we conduct similar analysis to study the evolution of rainfall extremes during austral spring (SON), fall (MAM) and winter (JJA). A relatively homogeneous region over southeastern South America, whose limits change little from season to season, is heavily affected by extreme precipitation events, as indicated by the value of the 95th percentile of daily rainfall, higher during the spring season (16.94 mm day−1) and lower in winter (13.79 mm day−1). From 1979 to 2013, extreme rainfall events are more frequent in spring (131 events) and less frequent in fall (112 events). Similar to summertime extreme events, synoptic-scale waves continue to be the main drivers of extreme precipitation over the region. The interaction between these waves and intraseasonal anomalies during the development of rainfall extremes over southeastern South America is observed especially during neutral ENSO and La Niña conditions. Warm ENSO phases tend to favor more frequent extremes in all three seasons and extreme events during El Niños are associated with synoptic waves, with no significant interaction with intraseasonal anomalies.
Similar content being viewed by others
References
Alvarez MS, Vera CS, Kiladis GN, Liebmann B (2015) Influence of the Madden–Julian oscillation on precipitation and surface air temperature in South America. Clim Dyn. doi:10.1007/s00382-015-2581-6
Berbery EH, Nógues-Paegle J, Horel JD (1992) Wavelike southern hemisphere extratropical teleconnections. J Atmos Sci 49:155–177
Carvalho LMV, Jones C, Liebmann B (2004) The South Atlantic convergence zone: intensity, form, persistence, relationships with intraseasonal to interannual activity and extreme rainfall. J Clim 17:88–108
Chen M, Shi W, Xie P, Silva VBS, Kousky VE, Higgins RW, Janowiak JE (2008) Assessing objective techniques for gauge-based analyses of global daily precipitation. J Geophys Res 113:D04110. doi:10.1029/2007JD009132
Cunningham CC, Cavalcanti IFA (2006) Intraseasonal modes of variability affecting the South Atlantic convergence zone. Int J Climatol 26:1165–1180
Gan AM, Rao VB (1994) The influence of the Andes Cordillera on transient disturbances. Mon Weather Rev 122:1141–1157
Garreaud RD (2000) Cold air incursions over subtropical South America: mean structure and dynamics. Mon Weather Rev 128:2544–2559
Grimm AM, Silva Dias PL (1995) Analysis of tropical-extratropical interaction with influence functions of a barotropic model. J Atmos Sci 52:3538–3555
Hirata F, Grimm AM (2015) The role of synoptic and intraseasonal anomalies on the life cycle of summer rainfall extremes over southeastern South America. Clim Dyn. doi:10.1007/s00382-015-2751-6
Hoskins BJ, Ambrizzi T (1993) Rossby wave propagation on a realistic longitudinally varying flow. J Atmos Sci 50:1661–1671
Jones C, Waliser DE, Lau KM, Stern W (2004) Global occurrences of extreme precipitation and the Madden-Julian Oscillation: observations and predictability. J Clim 17:4575–4589
Kalnay E, Kanamitsu M, Kistler R, Collins W, Deaven D, Gandin L, Iredell M, Saha S, Woollen J, Zhu Y, Chelliah M, Ebisuzaki W, Higgins W, Janowiak J, Mo KC, Ropelewski C, Wang J, Leetma A, Reynolds R, Jenne R, Joseph D (1996) The NCEP_NCAR 40 year reanalysis project. Bull Am Meteorol Soc 77:437–471
Liebmann B, Smith CA (1996) Description of a complete (interpolated) outgoing longwave radiation dataset. Bull Am Meteorol Soc 77:1275–1277
Liebmann B, Kiladis GN, Marengo JA, Ambrizzi T, Glick JD (1999) Submonthly convective variability over South America and the South Atlantic convergence zone. J Clim 12:1877–1891
Liebmann B, Kiladis GN, Vera CS, Saulo AC, Carvalho LMV (2004) Subseasonal variations of rainfall in South America in the vicinity of the low-level jet east of the Andes and comparison to those in the South Atlantic convergence zone. J Clim 17:3829–3842
Livezey RE, Chen WY (1983) Statistical field signficance and its determination by Monte Carlo techniques. Mon Weather Rev 111:46–59
Marengo JA, Cornejo A, Satyamurty P, Nobre C, Sea W (1997) Cold surges in tropical and extratropical South America: the strong event in June 1994. Mon Weather Rev 125:2759–2786
Mo KC, Higgins RW (1998) The Pacific-South American modes and tropical convection during the Southern Hemisphere winter. Mon Weather Rev 126:1581–1596
Mo KC, Nogés-Paegle J (2001) The Pacific-South American modes and their downstream effects. Int J Climatol 21(10):1211–1229
Nogués-Paegle J, Mo KC (1997) Alternating wet and dry conditions over South America during summer. Mon Weather Rev 125:279–291
Nogués-Paegle J, Byerle LA, Mo KC (2000) Intraseasonal modulation of South American summer precipitation. Mon Weather Rev 128:837–850
Tedeschi RG, Grimm AM, Cavalcanti IFA (2015) Influence of Central and East ENSO on extreme events of precipitation in South America during austral spring and summer. Int J Climatol 35:2045–2064. doi:10.1002/joc.4106
Vera CS, Vigliarolo PK (2000) A diagnostic study of cold air outbreaks over South America. Mon Weather Rev 128:3–24
Webster PJ, Chang H-R (1988) Energy accumulation and emanation at low latitudes: impacts of a zonally varying basic state. J Atmos Sci 45:803–829
Wheeler MC, Hendon HH (2004) An all-season real-time multivariate MJO index: development of an index for monitoring and prediction. Mon Weather Rev 132:1917–1932
Acknowledgments
This work was carried out with the support of the National Council for Scientific and Technological Development (CNPq-Brazil) Grant BJT 400547/2013-9, and with the aid of the Inter-American Institute for Global Change Research (IAI) Grant CRN3035, which is supported by the US National Science Foundation (Grant GEO-1128040).
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Hirata, F.E., Grimm, A.M. The role of synoptic and intraseasonal anomalies on the life cycle of rainfall extremes over South America: non-summer conditions. Clim Dyn 49, 313–326 (2017). https://doi.org/10.1007/s00382-016-3344-8
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00382-016-3344-8