• Aceituno, P., 1988: On the functioning of the Southern Oscillation in the South American sector. Part I: Surface climate. Mon. Wea. Rev.,116, 505–524.

  • Allen, M. R., and L. A. Smith, 1994: Investigating the origins and significance of low-frequency modes of climate variability. Geophys. Res. Lett.,21, 883–886.

  • ——, and ——, 1996: Monte Carlo SSA: Detecting irregular oscillations in the presence of colored noise. J. Climate,9, 3373–3404.

  • Deser, C., and M. L. Blackmon, 1993: Surface climate variations over the North Atlantic Ocean during winter: 1900–1989. J. Climate,6, 1743–1754.

  • ——, and ——, 1995: On the relationship between tropical and north Pacific sea surface temperature variations. J. Climate,8, 1677–1680.

  • Dettinger, M. D., C. M. Strong, W. Weibel, M. Ghil, and P. Yiou, 1995: Software for singular spectrum analysis of noisy time series. Eos, Trans. Amer. Geophys. Union,76, 12, 14, 21.

  • Diaz, A. F., C. D. Studzinski, and C. R. Mechoso, 1998: Relationships between precipitation anomalies in Uruguay and southern Brazil and sea surface temperature in the Pacific and Atlantic Oceans. J. Climate,11, 251–271.

  • Enfield, D. B., and D. A. Mayer, 1997: Tropical Atlantic sea surface temperature variability and its relation to El Niño–Southern Oscillation. J. Geophys. Res.,38, 359–379.

  • Garcia, N. O., and W. Vargas, 1997: The temporal climatic variability in the “Rio de la Plata” basin displayed by river discharges. Climate Change,102, 929–945.

  • Genta, J. L., G. Prerez-Perez-Iribarren, and C. R. Mechoso, 1998: A recent increasing trend in the streamflow of rivers in southeastern South America. J. Climate, in press.

  • Hastenrath, S., L. C. de Castro, and P. Aceituno, 1987: The Southern Oscillation in the tropical Atlantic sector. Contrib. Atmos. Phys.,60, 447–463.

  • Jiang, N., J. D. Neelin, and M. Ghil, 1995: Quasi-quadrennial and quasi-biennial variability in the equatorial Pacific. Climate Dyn.,12, 101–112.

  • Kawamura, R., 1994: A rotated EOF analysis of global sea surface temperature with interannual and interdecadal scale. J. Phys. Oceanogr.,24, 707–715.

  • Latif, M., R. Kleeman, and C. Eckert, 1997: Greenhouse warming, decadal variability, or El Niño? An attempt to understand the anomalous 1990s. J. Climate,10, 2221–2239.

  • Mann, M. E., and J. Park, 1994: Global-scale modes of surface temperature variability on interannual to century timescales. J. Geophys. Res.,99 (D12), 25 819–25 833.

  • ——, and J. M. Lees, 1996: Robust estimation of background noise and signal detection in climatic time series. Climate Change,33, 409–445.

  • Mechoso, C. R., and G. Perez-Iribarren, 1992: Streamflow in southeastern South America and the Southern Oscillation. J. Climate,5, 1535–1539.

  • Mehta, V. M., 1998: Variability of the tropical ocean surface temperatures at decadal–multidecadal timescales. Part I: The Atlantic Ocean. J. Climate,11, 2351–2375.

  • Moron, V., R. Vautard, and M. Ghil, 1997: Trends, interdecadal and interannual oscillations in the global sea-surface temperature. Climate Dyn., in press.

  • Nogués-Paegle, J., and K. C. Mo, 1997: Alternating wet and dry conditions over South America during summer. Mon. Wea. Rev.,125, 279–291.

  • Percival, D. B., and A. T. Walden, 1993: Spectral Analysis for Physical Applications. Cambridge University Press, 580 pp.

  • Pisciottano, G., A. Diaz, G. Cazes, and C. R. Mechoso, 1994: El Niño–Southern Oscillation impact on rainfall in Uruguay. J. Climate,7, 1286–1302.

  • Rasmusson, E. M., and T. H. Carpenter, 1983: The relationship between eastern equatorial Pacific sea-surface temperatures and rainfall over India and Sri Lanka. Mon. Wea. Rev.,111, 517–528.

  • Rayner, N. A., C. K. Folland, D. E. Parker, and E. B. Horton, 1995:A new global sea-ice and sea surface temperature (GISST) data set for 1903–1994 for forcing climate models. Hadley Centre Internal Note 69, 13 pp. [Available from the Meteorological Office, Bracknell, Berkshire RG12 2SZ, United Kingdom.].

  • Richman, M. B., 1986: Rotation of principal components. Int. J. Climatol.,6, 293–335.

  • Robertson, A. W., 1996: Interdecadal variability in a multicentury climate integration. Climate Dyn.,12, 227–241.

  • Ropelewski, C. F., and M. S. Halpert, 1987: Global and regional scale precipitation patterns associated with the El Niño/Southern Oscillation. Mon. Wea. Rev.,115, 1606–1626.

  • ——, and ——, 1989: Precipitation patterns associated with the high index phase of the Southern Oscillation. J. Climate,2, 268–284.

  • ——, and ——, 1996: Quantifying Southern Oscillation–precipitation relationships. J. Climate,9, 1043–1059.

  • Thomson, D. J., 1982: Spectrum estimation and harmonic analysis. Proc. Inst. Electr. Electronics Eng.,70, 1055–1096.

  • ——, 1990: Quadratic–inverse spectrum estimates: Application to palaeoclimatology. Philos. Trans. Roy. Soc. London,332A, 539–597.

  • Unal, Y., and M. Ghil, 1995: Interannual and interdecadal oscillation patterns in sea level. Climate Dyn.,11, 255–278.

  • Vautard, R., and M. Ghil, 1989: Singular spectrum analysis in nonlinear dynamics, with applications to paleoclimatic time series. Physica D,35D, 395–424.

  • ——, P. Yiou, and M. Ghil, 1992: Singular spectrum analysis: A toolkit for short, noisy, chaotic signals. Physica D,58, 95–126.

  • Venegas, S. A., L. A. Mysak, and D. N. Straub, 1996: Evidence for interannual and interdecadal climate variability in the South Atlantic. Geophys. Res. Lett.,23, 2673–2676.

  • Wagner, R. G., 1996: Decadal-scale trends in mechanisms controlling meridional sea surface temperature gradients in the tropical Atlantic. J. Geophys. Res.,101, 16 683–16 694.

  • Wang, B., 1995: Interdecadal changes in El Niño onset in the last four decades. J. Climate,8, 267–285.

  • Zhang, Y., J. M. Wallace, and D. S. Battisti, 1997: ENSO-like interdecadal variability: 1900–93. J. Climate,10, 1004–1020.

  • Zwiers, F. W., and H. von Storch, 1995: Taking serial correlation into account in tests of the mean. J. Climate,8, 336–351.

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Interannual and Decadal Cycles in River Flows of Southeastern South America

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  • 1 Department of Atmospheric Sciences, University of California, Los Angeles, Los Angeles, California
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Abstract

The time series of annual streamflow of four rivers in southeastern and south-central South America (the Negro, Paraguay, Paraná, and Uruguay Rivers) for the period 1911–93 are analyzed. Application of the multitaper method shows that the following features are significant at the 95% level: 1) a nonlinear trend, 2) a near-decadal component, and 3) interannual peaks with ENSO timescales. The trend and near-decadal components are most marked in the two more central rivers, the Paraguay and Paraná, with ENSO timescale variability most pronounced in the Negro and Uruguay rivers in the southeast. Composites of SST are made for each of the statistically significant oscillatory components of river flow, by reconstructing each component using singular spectrum analysis. These composites confirm the influence of ENSO on the streamflow variability of the Negro and Uruguay Rivers, with El Niño associated with enhanced streamflow. On the decadal timescale, high river runoff is associated with anomalously cool SSTs over the tropical North Atlantic. A very similar near-decadal oscillation in SST over this region is identified separately from a rotated empirical orthogonal function analysis of gridded annual mean SSTs. The near-decadal component of the Paraguay and Paraná Rivers is strongest in the austral summer.

Corresponding author address: Dr. Andrew W. Robertson, Dept. of Atmospheric Sciences, UCLA, 405 Hilgard Ave., Los Angeles, CA 90095-1565.

Email: andy@atmos.ucla.edu

Abstract

The time series of annual streamflow of four rivers in southeastern and south-central South America (the Negro, Paraguay, Paraná, and Uruguay Rivers) for the period 1911–93 are analyzed. Application of the multitaper method shows that the following features are significant at the 95% level: 1) a nonlinear trend, 2) a near-decadal component, and 3) interannual peaks with ENSO timescales. The trend and near-decadal components are most marked in the two more central rivers, the Paraguay and Paraná, with ENSO timescale variability most pronounced in the Negro and Uruguay rivers in the southeast. Composites of SST are made for each of the statistically significant oscillatory components of river flow, by reconstructing each component using singular spectrum analysis. These composites confirm the influence of ENSO on the streamflow variability of the Negro and Uruguay Rivers, with El Niño associated with enhanced streamflow. On the decadal timescale, high river runoff is associated with anomalously cool SSTs over the tropical North Atlantic. A very similar near-decadal oscillation in SST over this region is identified separately from a rotated empirical orthogonal function analysis of gridded annual mean SSTs. The near-decadal component of the Paraguay and Paraná Rivers is strongest in the austral summer.

Corresponding author address: Dr. Andrew W. Robertson, Dept. of Atmospheric Sciences, UCLA, 405 Hilgard Ave., Los Angeles, CA 90095-1565.

Email: andy@atmos.ucla.edu

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