Meteorology and Atmospheric Physics

, Volume 100, Issue 1–4, pp 37–52 | Cite as

Modelling the atmospheric response to SST dipole patterns in the South Indian Ocean with a regional climate model

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Summary

Previous observational work and experiments with global atmospheric circulation models have provided evidence that a dipole-like sea surface temperature (SST) pattern in the subtropical South Indian Ocean may influence austral summer rainfall over a southern African region stretching southeast from Zambia towards the south coast of South Africa. Increased rainfall tends to occur during positive events when the SW Indian Ocean anomaly is warm and the SE Indian Ocean anomaly is cool, and decreased rainfall during negative events when the SST anomalies are reversed.

In this study, the regional climate model MM5 is used to investigate the atmospheric response to two strong events of opposite sign (1981 and 1998). In general, the MM5 response is broadly consistent with NCEP re-analyses for these years but tends to advect more low level moisture over than NCEP. The model results indicate that more moisture is advected over the subcontinent from the South West Indian Ocean during the positive event than during the negative event. This is consistent with observed rainfall over the region during these events.

Keywords

Indian Ocean Global Precipitation Climatology Project Outgoing Long Wave Radiation South Indian Ocean South West Indian Ocean 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
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References

  1. Behera, SK, Yamagata, T 2001Subtropical SST dipole events in the southern Indian OceanGeophys Res Lett28327330CrossRefGoogle Scholar
  2. Cook, C, Reason, CJC, Hewitson, BC 2004Wet and dry spells within particular wet and dry summers in the South African summer rainfall regionClimate Res261731CrossRefGoogle Scholar
  3. d’Abreton, PC, Tyson, PD 1995Divergent and non-divergent water vapour transport over southern Africa during wet and dry conditionsMeteorol Atmos Phys554759CrossRefGoogle Scholar
  4. D’Abreton, PC, Tyson, PD 1996Three dimensional kinematic trajectory modelling of water vapour transport over southern AfricaWates SA22297306Google Scholar
  5. Harrison, MSJ 1984A generalized classification of South African summer rain-bearing synoptic systemsInt J Climatol4547560CrossRefGoogle Scholar
  6. Hirst, A, Hastenrath, S 1983Atmosphere-Ocean mechanisms of climate anomalies in Angola-tropical Atlantic sectorJ Phys Oceanogr1311461157CrossRefGoogle Scholar
  7. Huffman, GJ, Adler, FA, Arkin, P, Chang, F, Ferraro, R, Gruber, A, Janowiak, J, McNab, A, Rudolf, B, Schneider, U 1997The Global Precipitation Climatology Project (GPCP) combined data setBull Amer Meteorol Soc78520CrossRefGoogle Scholar
  8. Jury, MR, Pathack, B, Parker, B 1999Climatic determinants and statistical prediction of tropical cyclone days in the southwest Indian OceanJ Climate1217381746CrossRefGoogle Scholar
  9. Kalnay, E, Kanamitsu, M, Kistler, R, Collins, W, Deaven, D, Gandin, L, Iredell, M, Saha, S, White, G, Woollen, J, Zhu, Y, Chelliah, M, Ebisuzaki, W, Higgins, W, Janowiak, J, Mo, KC, Ropelewski, C, Wang, J, Leetmaa, A, Reynolds, R, Jenne, R, Joseph, D 1996The NCEP/NCAR 40-year reanalysis projectBull Amer Meteor Soc77437471CrossRefGoogle Scholar
  10. Landman, WA, Mason, SJ 1999Change in the association between Indian Ocean sea-surface temperature and summer rainfall over South Africa and NamibiaInt J Climatol1914771492CrossRefGoogle Scholar
  11. Mulenga, HM, Rouault, M, Reason, CJC 2003Dry summers over northeastern South Africa and associated circulation anomaliesClimate Res252941CrossRefGoogle Scholar
  12. Reason, CJC 2001Subtropical Indian Ocean SST dipole events and southern African rainfallGeophys Res Lett2822252227CrossRefGoogle Scholar
  13. Reason, CJC 2002Sensitivity of the southern African circulation to dipole sea-surface temperature patterns in the south Indian OceanInt J Climatol22377393CrossRefGoogle Scholar
  14. Reason, CJC, Mulenga, H 1999Relationships between South African rainfall and SST anomalies in the south west Indian OceanInt J Climatol1916511673CrossRefGoogle Scholar
  15. Reason, CJC, Landman, W, Tennant, W 2006Seasonal to decadal prediction of southern African climate and its links with variability of the Atlantic OceanBull Amer Met Soc87941955CrossRefGoogle Scholar
  16. Rocha, A, Simmonds, IH 1997Interannual variability of southern African summer rainfall. Part I: Relationships with air–sea interactions processesInt J Climatol17235265CrossRefGoogle Scholar
  17. Rouault M, Florenchie P, Fauchereau N, Reason CJC (2003) South East Tropical Atlantic Warm Events and Southern African Rainfall. Geophys Res Lett 30(5); DOI: 10.1029/2002/GL014840Google Scholar
  18. Tyson, PD, Preston-Whyte, RA 2000The Atmosphere and Weather of Southern AfricaOxford University PressCape TownGoogle Scholar
  19. Walker, ND 1990Links between South African summer rainfall and temperature variability of the Agulhas and Benguela current systemsJ Geophys Res9532973319CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  1. 1.Department of OceanographyUniversity of Cape TownRondeboschSouth Africa

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