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

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Amarasekera, K. N., Lee R. F. , Williams E. R. , and Eltahir E. A. B. , 1997: ENSO and the natural variability in the flow of tropical rivers. J. Hydrol, 200 , 2439.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Berri, G. S., Ghietto M. A. , and García N. O. , 2002: The influence of ENSO in the flows of the Upper Paraná River of South America over the past 100 years. J. Hydrometeor, 3 , 5765.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Bertoni, J. C., Maza J. A. , and Paoli C. U. , 2003: Inundaciones y drenaje urbano en la Argentina (Urban floods and drainage in Argentina). Inundações Urbanas na América do Sul (Urban Floods in South America), C. E. M. Tucci and J. C. Bertoni, Eds., Brazilian Water Resources Association, 471 pp.

    • Search Google Scholar
    • Export Citation
  • Bunning, R., and Pettras A. , 1979: Estudio de Crecidas de los Ríos Paraguay y Paraná. Hidrología Básica (Study of the basic Hydrology of the Paraguay and Paraná rivers). Entidad Binacional Yacyretá, Vol. 2, Motor Columbia, 13 pp.

    • Search Google Scholar
    • Export Citation
  • Camilloni, I., and Barros V. R. , 2000: The Paraná River response to El Niño 1982–83 and 1997–98 events. J. Hydrometeor, 1 , 412430.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Camilloni, I., and Barros V. R. , 2003: Extreme discharge events in the Paraná River and their climate forcing. J. Hydrol, 278 , 94106.

  • Collischonn, W., Tucci C. E. , and Clarke R. T. , 2001: Further evidence of changes in the hydrological regime of the River Paraguay: Part of a wider phenomenon of climate change? J. Hydrol, 245 , 218238.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Gan, M. A., and Rao V. B. , 1991: Surface cyclogenesis over South America. Mon. Wea. Rev, 119 , 12931302.

  • Garreaud, R. D., and Battisti D. S. , 1999: Interanual (ENSO) and interdecadal (ENSO-like) variability in the Southern Hemisphere tropospheric circulation. J. Climate, 12 , 21132123.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Genta, J. L., Pérez-Iribarren G. , and Mechoso C. R. , 1998: A recent increasing trend in the streamflow of rivers in southeastern South America. J. Climate, 11 , 28582862.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Grimm, A. M., Barros V. R. , and Doyle M. , 2000: Climate variability in southern South America associated with El Niño and La Niña events. J. Climate, 13 , 3558.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hamilton, S. K., 1999: Potential effects of a major navigation project (Paraguay-Paraná Hidrovía) on inundation in the Pantanal floodplains. Regul. Rivers: Res. Manage, 15 , 289299.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hidroservice–Louis Berger–EIH, 1996: Estudios de Factibilidad Técnìca y Económica de Obras de Ingeniería a Corto, Mediano y Largo Plazo. Hidrovía de los Ríos Paraguay y Paraná (Technical and economic feasibility study for the short, medium and long term engineering. Waterway of the Paraná-Paraguay rivers). Digital Rep. for Intergovernmental Committee of the Waterway of the Paraná-Paraguay Rivers.

    • 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.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Keeping, E. S., 1962: Introduction to Statistical Inference. D. Van Nostrand, 451 pp.

  • Kiladis, G. N., and Diaz H. F. , 1989: Global climatic anomalies associated with extremes in the Southern Oscillation. J. Climate, 2 , 10691090.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lacerda de Almeida, L., and Barros V. R. , 1998: Estudio de la relación entre la radiación de onda larga saliente (OLR) de la subcuenca del río Paraguay y el caudal en Puerto Bermejo (On the relation between outgoing long-wave radiation in the Paraguay River Basin and the Puerto Bermejo discharge). Meteorologica, 23 , 3746.

    • Search Google Scholar
    • Export Citation
  • Mo, K. C., 2000: Relationship between low-frequency variability in the Southern Hemisphere and sea surface temperature anomalies. J. Climate, 13 , 35993610.

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

    • Crossref
    • Search Google Scholar
    • Export Citation
  • National Emergency Committee of Paraguay, 1998: Campaña Salvavidas. Area Ambiental (Life Protection Campaign. Environmental Aspects.) United Nations Developing Program Final Rep., Asunción, Paraguay, 39 pp.

    • Search Google Scholar
    • Export Citation
  • Pisciottano, G., Diaz A. , Cazes G. , and Mechoso C. R. , 1994: El Niño–Southern Oscillation impact on rainfall in Uruguay. J. Climate, 7 , 12861302.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Renwick, J. A., 1998: ENSO related variability in the frequency of the South Pacific blocking. Mon. Wea. Rev, 126 , 41173123.

  • Robertson, A. W., Mechoso C. R. , and García N. O. , 2001: Interannual prediction of the Paraná River. Geophys. Res. Lett, 28 , 42354238.

  • Ropelewski, C. H., and Halpert S. , 1987: Global and regional scale precipitation patterns associated with El Niño/Southern Oscillation. Mon. Wea. Rev, 115 , 16001626.

    • Search Google Scholar
    • Export Citation
  • Ropelewski, C. H., and Halpert S. , 1996: Quantifying Southern Oscillation–precipitation relationships. J. Climate, 9 , 10431059.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Souza, E. B., Kayano M. T. , Tota J. , Pezzi I. , Fisch G. , and Nobre C. , 2000: On the influence of the El Niño, La Niña and Atlantic dipole pattern on the Amazonian rainfall during 1960–1998. Acta Amazonica, 30 , 305318.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Trenberth, K. E., 1997: The definition of El Niño. Bull. Amer. Meteor. Soc, 78 , 27712777.

  • Velasco, I., and Fritsch J. M. , 1987: Mesoscale convective complexes in the Americas. J. Geophys. Res, 92 (D8) 95919613.

  • Willmott, C. J., and Matsuura K. , cited 2001: Terrestrial air temperature and precipitation: Monthly and annual time series (1950– 99): Version 1.02. [Available online at http://climate.geog.udel.edu/~climate/=html_pages/archive.html#ged.].

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 351 198 12
PDF Downloads 172 98 9

The Major Discharge Events in the Paraguay River: Magnitudes, Source Regions, and Climate Forcings

View More View Less
  • 1 Department of Atmospheric and Ocean Sciences, University of Buenos Aires, and CONICET, Buenos Aires, Argentina
  • | 2 Department of Physics, University of Asunción, San Lorenzo, Paraguay
  • | 3 Meterological Service of Paraguay, Asunción, Paraguay
Restricted access

Abstract

The greatest discharges of the Paraguay River were studied using monthly series of Ladario, Brazil, at the outlet of the vast wetland of the Pantanal, and Asunción, Paraguay, at the middle Paraguay River outlet. Most of the major discharges at Asunción peaked between May and July, in phase with the annual maximum of the river discharges. They originated in the upper and middle Paraguay basins and were independent of the Pantanal output because their climate forcings were different from those of the Pantanal. In fact, most of the major discharge contributions from the upper and middle Paraguay basins occurred during El Niño (EN) periods, while at the Pantanal outlet they happened in neutral periods. The top discharge occurred during the autumn following the EN onset year. The composite of these cases has a tropospheric circulation that enhances the subtropical jet and the cyclonic vorticity advection over the Alto Paraná and the upper and middle Paraguay basins, favoring large positive anomalies in the precipitation field. Not all the major discharges were related to EN. Particularly, the major discharges that peaked in winter shared common features, despite their occurrence during EN, La Niña, or the neutral phases. Their April to August fields had an almost barotropic pattern at high latitudes with a deep cyclonic anomaly between 120° and 160°W and an anticyclonic anomaly over the southern tip of South America. This pattern is consistent with a northward shift of the synoptic perturbation tracks, which favors fields of positive precipitation anomalies over the Paraguay basin.

Corresponding author address: Vicente Barros, Department of Atmospheric and Oceanic Sciences, Pab. 2.P. 2, Ciudad Universitaria, 1428 Buenos Aires, Argentina. Email: barros@at.fcen.uba.ar

Abstract

The greatest discharges of the Paraguay River were studied using monthly series of Ladario, Brazil, at the outlet of the vast wetland of the Pantanal, and Asunción, Paraguay, at the middle Paraguay River outlet. Most of the major discharges at Asunción peaked between May and July, in phase with the annual maximum of the river discharges. They originated in the upper and middle Paraguay basins and were independent of the Pantanal output because their climate forcings were different from those of the Pantanal. In fact, most of the major discharge contributions from the upper and middle Paraguay basins occurred during El Niño (EN) periods, while at the Pantanal outlet they happened in neutral periods. The top discharge occurred during the autumn following the EN onset year. The composite of these cases has a tropospheric circulation that enhances the subtropical jet and the cyclonic vorticity advection over the Alto Paraná and the upper and middle Paraguay basins, favoring large positive anomalies in the precipitation field. Not all the major discharges were related to EN. Particularly, the major discharges that peaked in winter shared common features, despite their occurrence during EN, La Niña, or the neutral phases. Their April to August fields had an almost barotropic pattern at high latitudes with a deep cyclonic anomaly between 120° and 160°W and an anticyclonic anomaly over the southern tip of South America. This pattern is consistent with a northward shift of the synoptic perturbation tracks, which favors fields of positive precipitation anomalies over the Paraguay basin.

Corresponding author address: Vicente Barros, Department of Atmospheric and Oceanic Sciences, Pab. 2.P. 2, Ciudad Universitaria, 1428 Buenos Aires, Argentina. Email: barros@at.fcen.uba.ar

Save