• Aceituno, P., 1988: On the functioning of the Southern Oscillation in the South American sector. Part I: Surface climate. Mon. Wea. Rev., 116 , 505524.

    • Search Google Scholar
    • Export Citation
  • Aceituno, P., , and A. Montecinos, 1993: Stability analysis of the relation between the Southern Oscillation and rainfall in South America (in Spanish). Bull. Inst. Fr. Etudes Andines, 22 , 5361.

    • Search Google Scholar
    • Export Citation
  • Aceituno, P., , A. del Río, , and J. Rutllant, 1989: Rainfall anomalies in the subtropical west coast of South America. Part I: Relationship with SST and convective activity over the central Pacific. Preprints, Third Int. Conf. on Southern Hemisphere Meteorology and Oceanography, Buenos Aires, Argentina, Amer. Meteor. Soc.,. 162166.

    • Search Google Scholar
    • Export Citation
  • Berbery, E. H., , J. Nogués-Paegle, , and J. D. Horel, 1992: Wavelike Southern Hemisphere extratropical teleconnections. J. Atmos. Sci., 49 , 155177.

    • Search Google Scholar
    • Export Citation
  • Cook, K., 1998: On the response of the Southern Hemisphere to ENSO. Preprints, 23th Annual Climate Diagnostic and Prediction Workshop, Miami, FL, Amer. Meteor. Soc.,. 323326.

    • Search Google Scholar
    • Export Citation
  • Dole, R. M., 1983: Persistent anomalies of the extratropical Northern Hemisphere wintertime circulation. Large-Scale Dynamical Processes in the Atmosphere, B. J. Hoskins and R. P. Pearce, Eds., Academic Press,. 95110.

    • Search Google Scholar
    • Export Citation
  • Dole, R. M., , and N. D. Gordon, 1983: Persistent anomalies of the extratropical Northern Hemisphere wintertime circulation: Geographical distribution and regional persistence characteristics. Mon. Wea. Rev., 111 , 15671586.

    • Search Google Scholar
    • Export Citation
  • Fuenzalida, H., 1982: A country of extreme climate. Chile: Essence and Evolution (in Spanish), H. García, Ed., Instituto de Estudios Regionales de la Universidad de Chile,. 2735.

    • Search Google Scholar
    • Export Citation
  • Garreaud, R. D., 1995: Regional atmospheric configurations during major storms in central Chile (in Spanish). Meteorologica, 19 , 7381.

    • Search Google Scholar
    • Export Citation
  • Hurrell, J. W., , and K. E. Trenberth, 1999: Global sea surface temperature analyses: Multiple problems and their implications for climate analysis, modeling, and reanalysis. Bull. Amer. Meteor. Soc., 80 , 26612678.

    • Search Google Scholar
    • Export Citation
  • Kalnay, E., and Coauthors. . 1996: The NCEP/NCAR 40-Year Reanalysis Project. Bull. Amer. Meteor. Soc., 77 , 437471.

  • Karoly, D. J., 1989: Southern Hemisphere circulation features associated with El Niño–Southern Oscillation events. J. Climate, 2 , 12391252.

    • Search Google Scholar
    • Export Citation
  • Kidson, J. W., 1999: Principal modes of Southern Hemisphere low-frequency variability obtained from NCEP–NCAR reanalyses. J. Climate, 12 , 28062828.

    • Search Google Scholar
    • Export Citation
  • Kidson, J. W., , and M. R. Sinclair, 1995: The influence of persistent anomalies on Southern Hemisphere storm tracks. J. Climate, 8 , 19381950.

    • Search Google Scholar
    • Export Citation
  • Kiladis, G. N., , and K. C. Mo, 1998: Interannual and intraseasonal variability in the Southern Hemisphere. Meteorology of the Southern Hemisphere, D. J. Karoly and D. G. Vincent, Eds., Amer. Meteor. Soc.,. 307336.

    • Search Google Scholar
    • Export Citation
  • Marques, R. F. C., , and V. B. Rao, 1999: A diagnostic of a long-lasting blocking event over the southeast Pacific Ocean. Mon. Wea. Rev., 127 , 17611776.

    • Search Google Scholar
    • Export Citation
  • Marques, R. F. C., , and V. B. Rao, 2000: Interannual variations of blocking in the Southern Hemisphere and their energetics. J. Geophys. Res., 105 , 46254636.

    • Search Google Scholar
    • Export Citation
  • Miller, A., 1976: The climate of Chile. Climates of Central and South America,. W. Schwerdtfeger, Ed., Elsevier,. 113145.

  • Mo, K. C., , and G. H. White, 1985: Teleconnections in the Southern Hemisphere. Mon. Wea. Rev., 113 , 2237.

  • Mo, K. C., , and M. Ghil, 1987: Statistics and dynamics of persistent anomalies. J. Atmos. Sci., 44 , 877901.

  • Montecinos, A., 1998: Seasonal rainfall forecast in central Chile (in Spanish). M.S. thesis, Department of Geophysics, University of Chile, 116 pp.

    • Search Google Scholar
    • Export Citation
  • Montecinos, A., , A. Díaz, , and P. Aceituno, 2000a: Seasonal diagnostic and predictability of rainfall in subtropical South America based on tropical Pacific SST. J. Climate, 13 , 746758.

    • Search Google Scholar
    • Export Citation
  • Montecinos, A., , R. D. Garreaud, , and P. Aceituno, 2000b: Interdecadal rainfall variability in subtropical South America and its relationship with tropical Pacific SST. Preprints, Sixth Int. Conf. on Southern Hemisphere Meteorology and Oceanography, Santiago, Chile, Amer. Meteor. Soc.,. 6768.

    • Search Google Scholar
    • Export Citation
  • Pittock, A. B., 1980: Patterns of climatic variation in Argentina and Chile. Part I: Precipitation, 1931–1960. Mon. Wea. Rev., 108 , 13471361.

    • Search Google Scholar
    • Export Citation
  • Pizarro, J. G., , and A. Montecinos, 2000: Cutoff cyclones off the subtropical coast of Chile. Preprints, Sixth Int. Conf. on Southern Hemisphere Meteorology and Oceanography, Santiago, Chile, Amer. Meteor. Soc.,. 278279.

    • Search Google Scholar
    • Export Citation
  • Quinn, W., , and V. Neal, 1983: Long-term variations in the Southern Oscillation, El Niño and the Chilean subtropical rainfall. Fish. Bull., 81 , 363374.

    • Search Google Scholar
    • Export Citation
  • Rao, V. B., , S. H. Franchito, , and J. P. Reyes-Fernandez, 2000: Comments on “Blocking over the South Pacific and Rossby wave propagation.”. Mon. Wea. Rev., 128 , 41604161.

    • Search Google Scholar
    • Export Citation
  • Renwick, J. A., , and M. J. Revell, 1999: Blocking over the South Pacific and Rossby wave propagation. Mon. Wea. Rev., 127 , 22332247.

  • Renwick, J. A., , and M. J. Revell, 2000: Reply. Mon. Wea. Rev., 128 , 4162.

  • Reynolds, R. W., , and T. M. Smith, 1994: Improved global sea surface temperature analysis using optimum interpolation. J. Climate, 7 , 929948.

    • Search Google Scholar
    • Export Citation
  • Rubin, M. J., 1955: An analysis of pressure anomalies in the Southern Hemisphere. Notos, 4 , 1116.

  • Rutllant, J., , and H. Fuenzalida, 1991: Synoptic aspects of the central Chile rainfall variability associated with the Southern Oscillation. Int. J. Climatol., 11 , 6376.

    • Search Google Scholar
    • Export Citation
  • Shukla, J., , and K. C. Mo, 1983: Seasonal and geographical variation of blocking. Mon. Wea. Rev., 111 , 388402.

  • Sinclair, M. R., 1996: A climatology of anticyclones and blocking for the Southern Hemisphere. Mon. Wea. Rev., 124 , 245263.

  • Sinclair, M. R., , J. A. Renwick, , and J. W. Kidson, 1997: Low-frequency variability of Southern Hemisphere sea level pressure and weather system activity. Mon. Wea. Rev., 125 , 25312543.

    • Search Google Scholar
    • Export Citation
  • Smith, T. M., , R. W. Reynolds, , R. E. Livezey, , and D. C. Stokes, 1996: Reconstruction of historical sea surface temperatures using empirical orthogonal function. J. Climate, 9 , 14031420.

    • Search Google Scholar
    • Export Citation
  • Trenberth, K. E., 1982: Seasonality in Southern Hemisphere eddy statistics at 500 mb. J. Atmos. Sci., 39 , 25072520.

  • Trenberth, K. E., 1991: Storm tracks in the Southern Hemisphere. J. Atmos. Sci., 48 , 21592178.

  • Trenberth, K. E., , and K. C. Mo, 1985: Blocking in the Southern Hemisphere. Mon. Wea. Rev., 113 , 321.

  • Trenberth, K. E., , and D. J. Shea, 1987: On the evolution of the Southern Oscillation. Mon. Wea. Rev., 115 , 30783096.

  • Walker, G. T., , and E. W. Bliss, 1932: World weather. V. Mem. Roy. Meteor. Soc., 4 , 5384.

  • White, W. B., 2000: Influence of the Antarctic Circumpolar Wave on Australian precipitation from 1958 to 1997. J. Climate, 13 , 21252141.

    • Search Google Scholar
    • Export Citation
  • White, W. B., , and R. G. Peterson, 1996: An Antarctic Circumpolar Wave in surface pressure, wind, temperature and sea-ice extent. Nature, 380 , 699702.

    • Search Google Scholar
    • Export Citation
  • White, W. B., , and N. J. Cherry, 1999: Influence of the Antarctic Circumpolar Wave upon New Zealand temperature and precipitation during autumn–winter. J. Climate, 12 , 960976.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 102 102 20
PDF Downloads 85 85 16

Seasonality of the ENSO-Related Rainfall Variability in Central Chile and Associated Circulation Anomalies

View More View Less
  • 1 Department of Geophysics, Universidad de Chile, Santiago, Chile
© Get Permissions
Restricted access

Abstract

The seasonality of the ENSO–rainfall relationship in central Chile (30°–41°S) and associated circulation anomalies are studied using correlation and compositing techniques. During El Niño episodes there is a tendency for the occurrence of above-average precipitation between 30° and 35°S in winter [June–July–August (JJA)] and from 35° to 38°S in late spring [October–November (ON)], while rainfall deficit is typically observed from around 38° to 41°S during the following summer [January–February–March (JFM)], when El Niño reaches its maximum development. Opposite rainfall anomalies are characteristic during La Niña events. This study confirms results from previous investigations indicating that enhanced blocking activity over the Amundsen–Bellingshausen Seas area in the southeastern (SE) Pacific during El Niño is a key feature explaining the wet conditions in winter. It is also shown that the same circulation anomaly explains the relatively wet conditions in late spring in the 35°–38°S region during El Niño episodes. Furthermore, the southward displacement from winter to late spring of the area with significant ENSO-related rainfall anomalies seems associated with the seasonal migration of the boundary separating the region under the influence of the subtropical domain from the extratropical domain, where the westerly regime and associated disturbances prevail. Blocking episodes in the SE Pacific during El Niño seem to be part of a wave structure, particularly intense during spring, characterized by a sequence of positive and negative quasi-barotropic height anomalies stretching southeastward from the equator toward the SE Pacific and back to the southwestern Atlantic. On the other hand, anomalously dry conditions in winter and late spring during La Niña are favored by long-lasting and intense ridges at subtropical latitudes over the SE Pacific and South America resulting in a southward migration of the midlatitude storm tracks. In summer, a higher frequency of ridges in the southern tip of the South America during El Niño episodes presumably contributes to reinforcement of the southern edge of the subtropical anticyclone in the SE Pacific, which at this time of the year reaches its southernmost position, resulting in the annual rainfall minimum. On the other hand, an increased frequency of cyclonic circulation anomalies crossing the southern tip of the continent is associated with relatively wet conditions in southern-central Chile, particularly during La Niña events.

Current affiliation: Departamento de Oceanografía, Centro de Investigación Oceanográfica (COPAS), Universidad de Concepción, Concepcion, Chile

Corresponding author address: Aldo Montecinos, Departamento de Oceanografía, COPAS, Cabina 7, Casilla 160-C, Concepcion 3, Chile. Email: amonteci@profc.udec.cl

Abstract

The seasonality of the ENSO–rainfall relationship in central Chile (30°–41°S) and associated circulation anomalies are studied using correlation and compositing techniques. During El Niño episodes there is a tendency for the occurrence of above-average precipitation between 30° and 35°S in winter [June–July–August (JJA)] and from 35° to 38°S in late spring [October–November (ON)], while rainfall deficit is typically observed from around 38° to 41°S during the following summer [January–February–March (JFM)], when El Niño reaches its maximum development. Opposite rainfall anomalies are characteristic during La Niña events. This study confirms results from previous investigations indicating that enhanced blocking activity over the Amundsen–Bellingshausen Seas area in the southeastern (SE) Pacific during El Niño is a key feature explaining the wet conditions in winter. It is also shown that the same circulation anomaly explains the relatively wet conditions in late spring in the 35°–38°S region during El Niño episodes. Furthermore, the southward displacement from winter to late spring of the area with significant ENSO-related rainfall anomalies seems associated with the seasonal migration of the boundary separating the region under the influence of the subtropical domain from the extratropical domain, where the westerly regime and associated disturbances prevail. Blocking episodes in the SE Pacific during El Niño seem to be part of a wave structure, particularly intense during spring, characterized by a sequence of positive and negative quasi-barotropic height anomalies stretching southeastward from the equator toward the SE Pacific and back to the southwestern Atlantic. On the other hand, anomalously dry conditions in winter and late spring during La Niña are favored by long-lasting and intense ridges at subtropical latitudes over the SE Pacific and South America resulting in a southward migration of the midlatitude storm tracks. In summer, a higher frequency of ridges in the southern tip of the South America during El Niño episodes presumably contributes to reinforcement of the southern edge of the subtropical anticyclone in the SE Pacific, which at this time of the year reaches its southernmost position, resulting in the annual rainfall minimum. On the other hand, an increased frequency of cyclonic circulation anomalies crossing the southern tip of the continent is associated with relatively wet conditions in southern-central Chile, particularly during La Niña events.

Current affiliation: Departamento de Oceanografía, Centro de Investigación Oceanográfica (COPAS), Universidad de Concepción, Concepcion, Chile

Corresponding author address: Aldo Montecinos, Departamento de Oceanografía, COPAS, Cabina 7, Casilla 160-C, Concepcion 3, Chile. Email: amonteci@profc.udec.cl

Save