Article Type:
Research Article

Is the Recent Increasing Trend of Rainfall over Northeast Brazil Related to Sub-Saharan Drought?

V. Brahmananda Rao Centro de Previsão de Tempo e Estudos Climáticos, CPTEC Instituto Nacional de Pesquisas Espaciais, São José dos Campos, Sao Paolo, Brazil

Search for other papers by V. Brahmananda Rao in
Current site
Google Scholar
PubMed Close
,
Emanuel Giarolla Centro de Previsão de Tempo e Estudos Climáticos, CPTEC Instituto Nacional de Pesquisas Espaciais, São José dos Campos, Sao Paolo, Brazil

Search for other papers by Emanuel Giarolla in
Current site
Google Scholar
PubMed Close
,
Mary T. Kayano Centro de Previsão de Tempo e Estudos Climáticos, CPTEC Instituto Nacional de Pesquisas Espaciais, São José dos Campos, Sao Paolo, Brazil

Search for other papers by Mary T. Kayano in
Current site
Google Scholar
PubMed Close
, and
Sergio H. Franchito Centro de Previsão de Tempo e Estudos Climáticos, CPTEC Instituto Nacional de Pesquisas Espaciais, São José dos Campos, Sao Paolo, Brazil

Search for other papers by Sergio H. Franchito in
Current site
Google Scholar
PubMed Close
Print Publication:
01 Sep 2006
DOI:
https://doi.org/10.1175/JCLI3862.1
Page(s):
4448–4453
Restricted access

Abstract

In recent years, there has been an increase in rainfall over northeast Brazil (Nordeste), while over the sub-Saharan region there has been a drought. The correlation coefficients between the 11-yr running means of the rainfall series over the two regions are significant (at the 95% confidence level by a two-sided t test), suggesting that both trends are related. The rainfall variations over the two regions are connected to the position of the intertropical convergence zone (ITCZ) over the Atlantic. A more southward (northward) position of the ITCZ is favorable for higher than normal rainfall over Nordeste (sub-Sahara). The correlation coefficient between the position of the ITCZ over the Atlantic and the rainfall over Nordeste (sub-Sahara) is negative (positive) and highly significant, reaching values over 0.9. Thus, this study suggests that a more southward than normal location of the ITCZ in the Atlantic may be the cause for the recent increasing (decreasing) trend of rainfall over Nordeste (sub-Sahara).

Corresponding author address: Dr. V. B. Rao, Centro de Previsão de Tempo e Estudos Climáticos, CPTEC Instituto Nacional de Pesquisas Espaciais, INPE CP 515, 12245-970, São José dos Campos, SP, Brazil. Email: vbrao@cptec.inpe.br

Abstract

In recent years, there has been an increase in rainfall over northeast Brazil (Nordeste), while over the sub-Saharan region there has been a drought. The correlation coefficients between the 11-yr running means of the rainfall series over the two regions are significant (at the 95% confidence level by a two-sided t test), suggesting that both trends are related. The rainfall variations over the two regions are connected to the position of the intertropical convergence zone (ITCZ) over the Atlantic. A more southward (northward) position of the ITCZ is favorable for higher than normal rainfall over Nordeste (sub-Sahara). The correlation coefficient between the position of the ITCZ over the Atlantic and the rainfall over Nordeste (sub-Sahara) is negative (positive) and highly significant, reaching values over 0.9. Thus, this study suggests that a more southward than normal location of the ITCZ in the Atlantic may be the cause for the recent increasing (decreasing) trend of rainfall over Nordeste (sub-Sahara).

Corresponding author address: Dr. V. B. Rao, Centro de Previsão de Tempo e Estudos Climáticos, CPTEC Instituto Nacional de Pesquisas Espaciais, INPE CP 515, 12245-970, São José dos Campos, SP, Brazil. Email: vbrao@cptec.inpe.br

Save
Cover Journal of Climate
Journal of Climate

  • Cook, K. H., J. S. Hsieh, and S. M. Hagos, 2004: The Africa–South America intercontinental teleconnection. J. Climate, 17 , 2851–2865.

    • Search Google Scholar
    • Export Citation

  • Dai, A. G., P. J. Lamb, K. E. Trenberth, M. Hulme, P. D. Jones, and P. P. Xie, 2004: The recent Sahel drought is real. Int. J. Climatol., 24 , 1323–1331.

    • Search Google Scholar
    • Export Citation

  • Hagos, S. M., and K. H. Cook, 2005: Influence of surface processes over Africa on the Atlantic marine ITCZ and South American precipitation. J. Climate, 18 , 4993–5010.

    • Search Google Scholar
    • Export Citation

  • Hastenrath, S., 1995: Recent advances in tropical climate prediction. J. Climate, 8 , 1519–1532.

  • Hastenrath, S., 2000: Interannual and longer-term variability of upper air circulation in the Northeast Brazil–tropical Atlantic sector. J. Geophys. Res., 105 , 7327–7335.

    • Search Google Scholar
    • Export Citation

  • Hastenrath, S., and L. Heller, 1977: Dynamics of climatic hazards in northeast Brazil. Quart. J. Roy. Meteor. Soc., 103 , 77–92.

  • Hastenrath, S., and L. Greischar, 1993: Circulation mechanisms related to northeast Brazil rainfall anomalies. J. Geophys. Res., 98 , 5093–5102.

    • Search Google Scholar
    • Export Citation

  • Kalnay, E., and Coauthors, 1996: The NCEP/NCAR 40-Year Reanalysis Project. Bull. Amer. Meteor. Soc., 77 , 437–471.

  • Kayano, M. T., and R. V. Andreoli, 2004: Decadal variability of northern northeast Brazil rainfall and its relation to tropical sea surface temperature and global sea level pressure anomalies. J. Geophys. Res., 109 .C11011, doi:10.1029/2004JC002429.

    • Search Google Scholar
    • Export Citation

  • Marengo, J. A., J. Tomasella, and C. R. B. Uvo, 1998: Trends in streamflow and rainfall in tropical South America: Amazonia and eastern Brazil, and northwestern Peru. J. Geophys. Res., 103 , 1775–1783.

    • Search Google Scholar
    • Export Citation

  • Moura, A. D., and J. Shukla, 1981: On the dynamics of droughts in northeast Brazil: Observations, theory, and numerical experiments with a general circulation model. J. Atmos. Sci., 38 , 2653–2675.

    • Search Google Scholar
    • Export Citation

  • Moura, A. D., and S. Hastenrath, 2004: Climate prediction for Brazil’s Nordeste: Performance of empirical and numerical modeling methods. J. Climate, 17 , 2667–2672.

    • Search Google Scholar
    • Export Citation

  • Nicholson, S. E., 1994: Century-scale series of standardized annual departures of rainfall. Trends’ 93: A Compendium of Data on Global Change, ORNL/CDIAC-65, T. A. Boden et al., Eds., Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, 952–962.

  • Nobre, P., and J. Shukla, 1996: Variations of sea surface temperature, wind stress, and rainfall over the tropical Atlantic and South America. J. Climate, 9 , 2464–2479.

    • Search Google Scholar
    • Export Citation

  • Paegle, J. N., and K. C. Mo, 2002: Linkages between summer rainfall variability over South America and sea surface temperature anomalies. J. Climate, 15 , 1389–1407.

    • Search Google Scholar
    • Export Citation

  • Rao, V. B., K. Hada, and D. Herdies, 1995: On the severe drought of 1993 in Northeast Brazil. Int. J. Climatol., 15 , 697–704.

  • Rao, V. B., S. R. Chapa, and S. H. Franchito, 1999: Decadal variation of atmosphere–ocean in the tropical Atlantic and its relationship to the northeast Brazil rainfall. J. Meteor. Soc. Japan, 77 , 63–75.

    • Search Google Scholar
    • Export Citation

  • Rao, V. B., J. P. R. Fernandez, and S. H. Franchito, 2004: Quasi-stationary waves in the Southern Hemisphere during the El Niño and La Niña events. Ann. Geophys., 22 , 789–806.

    • Search Google Scholar
    • Export Citation

  • Stoeckenius, T., 1981: Interannual variations of tropical precipitation patterns. Mon. Wea. Rev., 109 , 1233–1247.

  • Trewartha, G. T., 1961: The Earth’s Problem Climates. University of Wisconsin Press, 334 pp.

  • Uvo, R. C. B., 1989: A zona de convergência intertropical (ZCIT) e sua relação com a precipitação da região norte do nordeste brasileiro (in Portuguese). M.S. dissertation, Department of Meteorology, Instituto Nacional de Pesquisas Espaciais, 99 pp.

  • Wagner, R. G., 1996: Decadal-scale trends in mechanisms controlling meridional sea surface temperature gradients in the tropical Atlantic. J. Geophys. Res., 101 , 16683–16694.

    • Search Google Scholar
    • Export Citation

  • Walker, G. T., 1928: Ceara (Brazil) famines and the general air movement. Beitr. Phys. Atmos., 14 , 88–93.

  • Zhang, C., and H. H. Hendon, 1997: Propagating and standing components of the intraseasonal oscillation in tropical convection. J. Atmos. Sci., 54 , 741–752.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 164 53 5
PDF Downloads 110 55 7