• 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.

  • Barnett, T. P., and R. W. Preisendorfer, 1987: Origins and levels of monthly and seasonal forecast skill for United States surface air temperatures determined by canonical correlation analysis. Mon. Wea. Rev.,115, 1825–1850.

  • Casarin, D. P., and V. E. Kousky, 1986: Precipitation anomalies in the southern part of Brazil and variations of the atmospheric circulation. Rev. Bras. Meteor.,1, 83–90.

  • Enfield, D. B., 1996: Relationships of inter-American rainfall to tropical Atlantic and Pacific SST variability. Geophys. Res. Lett.,23, 3305–3308.

  • Gan, M. A., and V. B. Rao, 1991: Surface cyclogenesis over South America. Mon. Wea. Rev.,119, 1293–1302.

  • Graham, N. E., J. Michaelsen, and T. P. Barnett, 1987a: Investigations of the El Niño Southern Oscillation with statistical models. 1: Predictor field characteristics. J. Geophys. Res.,92, 14251–14270.

  • ——, ——, and ——, 1987b: Investigations of the El Niño Southern Oscillation with statistical models. 2: Model results. J. Geophys. Res.,92, 14271–14290.

  • Grimm, A. M., and P. L. Silva Dias, 1995: Analysis of tropical–extratropical interactions with influence functions of a barotropic model. J. Atmos. Sci.,52, 3538–3555.

  • Lau, K. M., and P. J. Sheu, 1988: Annual cycle, quasi-biennial oscillation, and Southern Oscillation in global precipitation. J. Geophys. Res.,93, 10975–10988.

  • Lau, N., and P. H. Chan, 1983: Short-term climate variability and atmospheric response to observed outgoing longwave radiation. Part I: Simultaneous relationship. J. Atmos. Sci.,40, 2735–2750.

  • ——, and M. J. Nath, 1990: A general circulation model study of the atmospheric response to extratropical sea surface temperature anomalies observed in 1950–1979. J. Climate,3, 965–989.

  • Logue, J. J., 1984: Regional variations in the annual cycle of rainfall in Ireland as revealed by principal component analysis. J. Climatol.,4, 597–607.

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

  • North, G. R., T. L. Bell, R. F. Cahalan, and F. J. Moeng, 1982: Sampling errors in the estimation of empirical orthogonal functions. Mon. Wea. Rev.,110, 699–706.

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

  • Preisendorfer, R. W., 1988: Principal Component Analysis in Meteorology and Oceanography. Elsevier, 418 pp.

  • Prohaska, F., 1976: The climate of Argentina, Paraguay and Uruguay. Climates of Central and South America, W. Schwerdtfeger, Ed., World Survey of Climatology, Vol. 12, Elsevier, 13–112.

  • Rao, V. B., and K. Hada, 1990: Characteristics of rainfall over Brazil:Annual variations and connections with the Southern Oscillation. Theor. Appl. Climatol.,42, 81–91.

  • 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 high index phase of Southern Oscillation. J. Climate,2, 268–284.

  • Silva Dias, M. A., 1987: Sistemas de mesoescala e previsao de tempo a curto prazo. Rev. Bras. Meteor.,2, 133–150.

  • Terra, R., and G. J. Pisciottano, 1994: Regionalización del Uruguay según el ciclo anual de precipitaciones mediante “Cluster Analysis.” Memorias XVI Congreso Latinoamericano de Hidráulica, Santiago, Chile, IAHR, 227–236.

  • Velasco, I., and J. M. Fritsch, 1987: Mesoscale convective complexes over the Americas. J. Geophys. Res.,92, 9591–9613.

  • Zebiak, S. E., 1993: Air–sea interaction in the equatorial Atlantic region. J. Climate,6, 1567–1586.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 250 250 131
PDF Downloads 93 93 15

Relationships between Precipitation Anomalies in Uruguay and Southern Brazil and Sea Surface Temperature in the Pacific and Atlantic Oceans

View More View Less
  • 1 Instituto de Mecánica de los Fluidos e Ingeniería Ambiental, Universidad de la República, Montevideo, Uruguay
  • | 2 Centro de Previsao do Tempo e Estudos Climáticos, Instituto Nacional de Pesquisas Espaciais, Cachoeira Paulista, Sao Paulo, Brazil
  • | 3 Department of Atmospheric Sciences, University of California, Los Angeles, Los Angeles, California
© Get Permissions
Restricted access

Abstract

This study focuses on precipitation in Uruguay and the Brazilian state of Rio Grande do Sul, which extend along the Atlantic coast of southern South America. The present paper has two principal goals: 1) to describe the annual cycle of precipitation and 2) to investigate the relationships between its anomalies and those in sea surface temperature (SST) in the Pacific and Atlantic oceans. The dataset is provided by 40 rainfall stations almost evenly distributed in space and covers the period 1917–80. The tools used in support of this research include principal component and canonical correlation analyses.

It is found that total precipitation tends to be evenly distributed during the year. The largest spatial variability in the monthly deviations from the annual mean appears as a west–east (inland–coastal) dipole with the largest positive values in the west during early fall and midspring, and in the east along the Atlantic coast during winter. The second mode of rainfall variability appears as a north–south dipole with the largest positive values in the south during late summer and late fall, and in the north during early spring and early summer. The third mode appears primarily as a north–south dipole along the western boundary with the largest positive values in the southwest during fall and in the northwest during early spring. These modes explain 60%, 19%, and 8% of the total variance. Five subregions are identified according to similarities between the characteristics of the annual cycles in their rainfall stations.

It is shown that there are significant relationships between anomalies in rainfall and in SST in the Pacific and Atlantic oceans. Some of these relationships confirm the results of previous studies, such as the links between the El Niño–Southern Oscillation phenomenon in the equatorial Pacific Ocean and rainfall anomalies in Uruguay during late spring–early summer and late fall–early winter. Other relationships have not been reported before, such as the links between SST anomalies in the southwestern Atlantic Ocean and rainfall anomalies in the entire region during October–December and April–July. It is also found that when SST anomalies are considered in both oceans simultaneously, their links with rainfall anomalies are in some cases enhanced and in others weakened.

Corresponding author address: Ing. Alvaro F. Díaz, Facultad de Ingeniería, Instituto de Mecánica de los Fluidos e Ingeniería Ambiental, Julio Herrera y Reissig 565, Montevideo 11300, Uruguay.

Email: adiaz@fing.edu.uy

Abstract

This study focuses on precipitation in Uruguay and the Brazilian state of Rio Grande do Sul, which extend along the Atlantic coast of southern South America. The present paper has two principal goals: 1) to describe the annual cycle of precipitation and 2) to investigate the relationships between its anomalies and those in sea surface temperature (SST) in the Pacific and Atlantic oceans. The dataset is provided by 40 rainfall stations almost evenly distributed in space and covers the period 1917–80. The tools used in support of this research include principal component and canonical correlation analyses.

It is found that total precipitation tends to be evenly distributed during the year. The largest spatial variability in the monthly deviations from the annual mean appears as a west–east (inland–coastal) dipole with the largest positive values in the west during early fall and midspring, and in the east along the Atlantic coast during winter. The second mode of rainfall variability appears as a north–south dipole with the largest positive values in the south during late summer and late fall, and in the north during early spring and early summer. The third mode appears primarily as a north–south dipole along the western boundary with the largest positive values in the southwest during fall and in the northwest during early spring. These modes explain 60%, 19%, and 8% of the total variance. Five subregions are identified according to similarities between the characteristics of the annual cycles in their rainfall stations.

It is shown that there are significant relationships between anomalies in rainfall and in SST in the Pacific and Atlantic oceans. Some of these relationships confirm the results of previous studies, such as the links between the El Niño–Southern Oscillation phenomenon in the equatorial Pacific Ocean and rainfall anomalies in Uruguay during late spring–early summer and late fall–early winter. Other relationships have not been reported before, such as the links between SST anomalies in the southwestern Atlantic Ocean and rainfall anomalies in the entire region during October–December and April–July. It is also found that when SST anomalies are considered in both oceans simultaneously, their links with rainfall anomalies are in some cases enhanced and in others weakened.

Corresponding author address: Ing. Alvaro F. Díaz, Facultad de Ingeniería, Instituto de Mecánica de los Fluidos e Ingeniería Ambiental, Julio Herrera y Reissig 565, Montevideo 11300, Uruguay.

Email: adiaz@fing.edu.uy

Save