• Ambrizzi, T., , and B. J. Hoskins, 1997: Stationary Rossby-wave propagation in a baroclinic atmosphere. Quart. J. Roy. Meteor. Soc., 123 , 919928.

    • Search Google Scholar
    • Export Citation
  • Arkin, P. A., 1982: The relationship between interannual variability in the 200 mb tropical wind field and the Southern Oscillation. Mon. Wea. Rev., 110 , 13931404.

    • Search Google Scholar
    • Export Citation
  • Behera, S. K., , and T. Yamagata, 2001: Subtropical SST dipole events in the southern Indian Ocean. Geophys. Res. Lett., 28 , 327330.

  • Berbery, E. H., , J. N. Paegle, , and J. D. Horel, 1992: Wavelike Southern Hemisphere extratropical teleconnections. J. Atmos. Sci., 49 , 155177.

    • Search Google Scholar
    • Export Citation
  • Black, E., , J. Slingo, , and K. R. Sperber, 2003: An observational study of the relationship between excessively strong short rains in coastal East Africa and Indian Ocean SST. Mon. Wea. Rev., 131 , 7494.

    • Search Google Scholar
    • Export Citation
  • Buizer, J. L., , J. Foster, , and D. Lund, 2000: Global impacts and regional actions: Preparing for the 1997/98 El Niño. Bull. Amer. Meteor. Soc., 81 , 21212139.

    • Search Google Scholar
    • Export Citation
  • Chen, T-C., 1985: Global water vapor flux and maintenance during FGGE. Mon. Wea. Rev., 113 , 18011819.

  • Chiang, J. C. H., , and A. H. Sobel, 2002: Tropical tropospheric temperature variations caused by ENSO and their influence on the remote tropical climate. J. Climate, 15 , 26162631.

    • Search Google Scholar
    • Export Citation
  • Colberg, F., , C. J. C. Reason, , and K. Rodgers, 2004: South Atlantic response to El Niño–Southern Oscillation induced climate variability in an ocean general circulation model. J. Geophys. Res., 109 .C12015, doi:10.1029/2004JC002301.

    • Search Google Scholar
    • Export Citation
  • Cook, K. H., 2000: The South Indian convergence zone and interannual rainfall variability over southern Africa. J. Climate, 13 , 37893804.

    • Search Google Scholar
    • Export Citation
  • D’Abreton, P. C. D., , and J. A. Lindesay, 1993: Water vapor transport over southern Africa during wet and dry early and late summer months. Int. J. Climatol., 13 , 151170.

    • Search Google Scholar
    • Export Citation
  • D’Abreton, P. C. D., , and P. D. Tyson, 1995: Divergent and non-divergent water vapour transport over southern Africa during wet and dry conditions. Meteor. Atmos. Phys., 55 , 4759.

    • Search Google Scholar
    • Export Citation
  • Goddard, L., , and N. E. Graham, 1999: Importance of the Indian Ocean for simulating rainfall anomalies over eastern and southern Africa. J. Geophys. Res., 104 , 1909919116.

    • Search Google Scholar
    • Export Citation
  • Hines, K. M., , D. H. Bromwich, , and G. J. Marshall, 2000: Artificial surface pressure trends in the NCEP–NCAR reanalysis over the Southern Ocean and Antarctica. J. Climate, 13 , 39403952.

    • Search Google Scholar
    • Export Citation
  • Hoskins, B. J., , and T. Ambrizzi, 1993: Rossby wave propagation on a realistic longitudinally varying flow. J. Atmos. Sci., 50 , 16611671.

    • Search Google Scholar
    • Export Citation
  • Jury, M. R., 1996: Regional teleconnection patterns associated with summer rainfall over South Africa, Namibia and Zimbabwe. Int. J. Climatol., 16 , 135153.

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

    • Search Google Scholar
    • Export Citation
  • Kistler, R., and Coauthors, 2001: The NCEP–NCAR 50-Year Reanalysis: Monthly means CD-ROM and documentation. Bull. Amer. Meteor. Soc., 82 , 247267.

    • Search Google Scholar
    • Export Citation
  • Kuhnel, I., 1989: Tropical–extratropical cloudband climatology. Int. J. Climatol., 9 , 441463.

  • Landman, W. A., , and S. J. Mason, 1999: Change in the association between Indian Ocean sea-surface temperatures and summer rainfall over South Africa and Namibia. Int. J. Climatol., 19 , 14771492.

    • Search Google Scholar
    • Export Citation
  • Latif, M., , D. Dommenget, , M. Dima, , and A. Grötzner, 1999: The role of Indian Ocean sea surface temperature in forcing East African rainfall anomalies during December–January 1997/98. J. Climate, 12 , 34973504.

    • Search Google Scholar
    • Export Citation
  • Lindesay, J. A., , and C. H. Vogel, 1990: Historical evidence for Southern Oscillation–southern African rainfall relationships. Int. J. Climatol., 10 , 679689.

    • Search Google Scholar
    • Export Citation
  • Lindesay, J. A., , M. S. J. Harrison, , and M. P. Haffner, 1986: The Southern Oscillation and South African rainfall. S. Afr. J. Sci., 82 , 196198.

    • Search Google Scholar
    • Export Citation
  • Loschnigg, J., , G. A. Meehl, , P. J. Webster, , J. M. Arblaster, , and G. P. Compo, 2003: The Asian monsoon, the tropospheric biennial oscillation, and the Indian Ocean zonal mode in the NCAR CSM. J. Climate, 16 , 16171642.

    • Search Google Scholar
    • Export Citation
  • Mason, S. J., 1995: Sea-surface temperature–South African rainfall associations, 1910–1989. Int. J. Climatol., 15 , 119135.

  • Mason, S. J., , and M. R. Jury, 1997: Climatic variability and change over southern Africa: A reflection on underlying processes. Prog. Phys. Geogr., 21 , 2350.

    • Search Google Scholar
    • Export Citation
  • Mason, S. J., , and P. D. Tyson, 2000: The occurrence and predictability of droughts over southern Africa. Drought: A Global Assessment, D. A. Wilhite, Ed., Vol. II, Routledge, 113–134.

  • Mason, S. J., , and L. Goddard, 2001: Probabilistic precipitation anomalies associated with ENSO. Bull. Amer. Meteor. Soc., 82 , 619638.

    • Search Google Scholar
    • Export Citation
  • Mason, S. J., , L. Goddard, , N. E. Graham, , E. Yulaeva, , L. Sun, , and P. A. Arkin, 1999: The IRI seasonal climate prediction system and the 1997/98 El Niño event. Bull. Amer. Meteor. Soc., 80 , 18531873.

    • Search Google Scholar
    • Export Citation
  • Matarira, C. H., 1990: Drought over Zimbabwe in a regional and global context. Int. J. Climatol., 10 , 609625.

  • Mo, K. C., 2000: Relationships between low-frequency variability in the Southern Hemisphere and sea surface temperature anomalies. J. Climate, 13 , 35993610.

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

  • Mo, K. C., , and J. N. Paegle, 2001: The Pacific–South American modes and their downstream effects. Int. J. Climatol., 21 , 12111229.

  • Moron, V., , S. Bigot, , and P. Roucou, 1995: Rainfall variability in subequatorial America and Africa and relationships with the main sea-surface temperature modes (1950–1990). Int. J. Climatol., 15 , 12971322.

    • Search Google Scholar
    • Export Citation
  • New, M., , M. Hulme, , and P. Jones, 1999: Representing twentieth-century space–time climate variability. Part I: Development of a 1961–90 mean monthly terrestrial climatology. J. Climate, 12 , 829856.

    • Search Google Scholar
    • Export Citation
  • New, M., , M. Hulme, , and P. Jones, 2000: Representing twentieth-century space–time climate variability. Part II: Development of 1901–96 monthly grids of terrestrial surface climate. J. Climate, 13 , 22172238.

    • Search Google Scholar
    • Export Citation
  • New, M., , M. Todd, , M. Hulme, , and P. D. Jones, 2001: Precipitation measurements and trends in the Twentieth Century. Int. J. Climatol., 21 , 18991922.

    • Search Google Scholar
    • Export Citation
  • Nicholson, S. E., , and D. Entekhabi, 1987: Rainfall variability in equatorial and southern Africa: Relationships with sea surface temperatures along the southwestern coast of Africa. J. Climate Appl. Meteor., 26 , 561578.

    • Search Google Scholar
    • Export Citation
  • Palmer, T. N., and Coauthors, 2004: Development of a European Multimodel Ensemble System for Seasonal-to-Interannual Prediction (DEMETER). Bull. Amer. Meteor. Soc., 85 , 853872.

    • Search Google Scholar
    • Export Citation
  • Rasmusson, E. M., , and T. H. Carpenter, 1982: Variations in tropical sea surface temperature and surface wind fields associated with the Southern Oscillation/El Niño. Mon. Wea. Rev., 110 , 354384.

    • Search Google Scholar
    • Export Citation
  • Reason, C. J. C., 2002: Sensitivity of the southern African circulation to dipole sea-surface temperature patterns in the South Indian Ocean. Int. J. Climatol., 22 , 377393.

    • Search Google Scholar
    • Export Citation
  • Reason, C. J. C., , and H. Mulenga, 1999: Relationships between South African rainfall and SST anomalies in the southwest Indian Ocean. Int. J. Climatol., 19 , 16511673.

    • Search Google Scholar
    • Export Citation
  • Reason, C. J. C., , and D. Jagadheesha, 2005: A model investigation of recent ENSO impacts over southern Africa. Meteor. Atmos. Phys., 89 , 181205.

    • Search Google Scholar
    • Export Citation
  • Reason, C. J. C., , R. J. Allan, , J. A. Lindesay, , and T. J. Ansell, 2000: ENSO and climatic signals across the Indian Ocean basin in the global context: Part I, interannual composite patterns. Int. J. Climatol., 20 , 12851327.

    • Search Google Scholar
    • Export Citation
  • Richard, Y., , N. Fauchereau, , I. Poccard, , M. Rouault, , and S. Trzaska, 2001: 20th century droughts in Southern Africa: Spatial and temporal variability, teleconnections with oceanic and atmospheric conditions. Int. J. Climatol., 21 , 873885.

    • Search Google Scholar
    • Export Citation
  • Rocha, A., , and I. Simmonds, 1997a: Interannual variability of south-eastern African summer rainfall. Part I: Relationships with air–sea interaction processes. Int. J. Climatol., 17 , 235265.

    • Search Google Scholar
    • Export Citation
  • Rocha, A., , and I. Simmonds, 1997b: Interannual variability of south-eastern African summer rainfall. Part II: Modeling the impact of sea-surface temperatures on rainfall and circulation. Int. J. Climatol., 17 , 267290.

    • Search Google Scholar
    • Export Citation
  • Ropelewski, C. F., , and M. S. Halpert, 1987: Global and regional scale precipitation and temperature patterns associated with El Niño–Southern Oscillation. Mon. Wea. Rev., 115 , 16061626.

    • Search Google Scholar
    • Export Citation
  • Rouault, M., , and Y. Richard, 2003: Intensity and spatial extension of drought in South Africa at different time scales. Water SA, 29 , 489500.

    • Search Google Scholar
    • Export Citation
  • Rouault, M., , P. Florenchie, , N. Fauchereau, , and C. J. C. Reason, 2003: South east tropical Atlantic warm events and southern African rainfall. Geophys. Res. Lett., 30 .8009, doi:10.1029/2002GL014840.

    • Search Google Scholar
    • Export Citation
  • Saji, N. H., , and T. Yamagata, 2003: Structure of SST and surface wind variability during Indian Ocean dipole mode events: COADS observations. J. Climate, 16 , 27352751.

    • Search Google Scholar
    • Export Citation
  • Saji, N. H., , B. N. Goswami, , P. N. Vinayachandran, , and T. Yamagata, 1999: A dipole mode in the tropical Indian Ocean. Nature, 401 , 360363.

    • Search Google Scholar
    • Export Citation
  • Smith, T. M., , and R. W. Reynolds, 2003: Extended reconstruction of global sea surface temperatures based on COADS data (1854–1997). J. Climate, 16 , 14951510.

    • Search Google Scholar
    • Export Citation
  • Sobel, A. H., , I. M. Held, , and C. S. Bretherton, 2002: The ENSO signal in tropical tropospheric temperature. J. Climate, 15 , 27022706.

    • Search Google Scholar
    • Export Citation
  • Su, H., , J. D. Neelin, , and C. Chou, 2001: Tropical teleconnection and local response to SST anomalies during the 1997–98 El Niño. J. Geophys. Res., 106D , 2002520044.

    • Search Google Scholar
    • Export Citation
  • Todd, M., , and R. Washington, 1999: Circulation anomalies associated with tropical-temperate troughs in southern Africa and the southwest Indian Ocean. Climate Dyn., 15 , 937951.

    • Search Google Scholar
    • Export Citation
  • Trenberth, K. E., 1980: Planetary waves at 500 mb in the Southern Hemisphere. Mon. Wea. Rev., 108 , 13781389.

  • Trenberth, K. E., , and C. J. Guillemot, 1998: Evaluation of the atmospheric moisture and hydrologic cycle in the NCEP/NCAR reanalyses. Climate Dyn., 14 , 213231.

    • Search Google Scholar
    • Export Citation
  • Tyson, P. D., 1981: Atmospheric circulation variations and the occurrence of extended wet and dry spells over southern Africa. J. Climatol., 1 , 115130.

    • Search Google Scholar
    • Export Citation
  • Walker, N. D., 1990: Links between South African summer rainfall and temperature variability of the Agulhas and Benguela system. J. Geophys. Res., 95 , 32973319.

    • Search Google Scholar
    • Export Citation
  • Webster, P. J., , A. M. Moore, , J. P. Loschnigg, , and R. R. Leben, 1999: Coupled ocean–atmosphere dynamics in the Indian Ocean during 1997–98. Nature, 401 , 356360.

    • Search Google Scholar
    • Export Citation
  • Xie, P., , and P. A. Arkin, 1996: Analysis of global monthly precipitation using gauge observations, satellite estimates, and numerical model predictions. J. Climate, 9 , 840858.

    • Search Google Scholar
    • Export Citation
  • Xie, S-P., , H. Annamalai, , F. A. Schott, , and J. P. McCreary Jr., 2002: Structure and mechanisms of south Indian Ocean climate variability. J. Climate, 15 , 864878.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 87 87 22
PDF Downloads 67 67 21

The 1997–98 Summer Rainfall Season in Southern Africa. Part I: Observations

View More View Less
  • 1 International Research Institute for Climate and Society, The Earth Institute at Columbia University, Palisades, New York
© Get Permissions
Restricted access

Abstract

Following the onset of the strong El Niño of 1997–98 historical rainfall teleconnection patterns and dynamical model predictions both suggested an enhanced likelihood of drought for southern Africa, but widespread dry conditions failed to materialize. Results from a diagnostic study of NCEP–NCAR reanalysis data are reported here demonstrating how the large- and regional-scale atmospheric circulations during the 1997–98 El Niño differed from previous events. Emphasis is placed on the January–March 1998 season and comparisons with the strong 1982–83 El Niño, although composites of eight events occurring between 1950 and 2000 are also considered. In a companion paper, simulation runs from three atmospheric general circulation models (AGCMs), and forecasts from three fully coupled models are employed to investigate the extent to which the anomalous atmospheric circulation patterns during the 1997–98 El Niño may have been anticipated.

Observational results indicate that the 1997–98 El Niño displayed significant differences from both the 1982–83 episode and the composite event. An unusually strong Angola low, exceptionally high sea surface temperatures (SSTs) in the western Indian and eastern tropical South Atlantic Oceans, and an enhanced northerly moisture flux from the continental interior and the western tropical Indian Ocean all appear to have contributed to more seasonal rainfall in 1997–98 over much of the southern Africa subcontinent than in past El Niño events.

Corresponding author address: Dr. Bradfield Lyon, International Research Institute for Climate and Society, 61 Route 9W, Palisades, NY 10964. Email: blyon@iri.columbia.edu

Abstract

Following the onset of the strong El Niño of 1997–98 historical rainfall teleconnection patterns and dynamical model predictions both suggested an enhanced likelihood of drought for southern Africa, but widespread dry conditions failed to materialize. Results from a diagnostic study of NCEP–NCAR reanalysis data are reported here demonstrating how the large- and regional-scale atmospheric circulations during the 1997–98 El Niño differed from previous events. Emphasis is placed on the January–March 1998 season and comparisons with the strong 1982–83 El Niño, although composites of eight events occurring between 1950 and 2000 are also considered. In a companion paper, simulation runs from three atmospheric general circulation models (AGCMs), and forecasts from three fully coupled models are employed to investigate the extent to which the anomalous atmospheric circulation patterns during the 1997–98 El Niño may have been anticipated.

Observational results indicate that the 1997–98 El Niño displayed significant differences from both the 1982–83 episode and the composite event. An unusually strong Angola low, exceptionally high sea surface temperatures (SSTs) in the western Indian and eastern tropical South Atlantic Oceans, and an enhanced northerly moisture flux from the continental interior and the western tropical Indian Ocean all appear to have contributed to more seasonal rainfall in 1997–98 over much of the southern Africa subcontinent than in past El Niño events.

Corresponding author address: Dr. Bradfield Lyon, International Research Institute for Climate and Society, 61 Route 9W, Palisades, NY 10964. Email: blyon@iri.columbia.edu

Save