Climate Dynamics

, Volume 39, Issue 12, pp 2895–2916 | Cite as

Tropical-temperate interactions over southern Africa simulated by a regional climate model

Article
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Abstract

The Weather Research and Forecasting model (WRF) forced by ERA40 re-analyses, is used to examine, at regional scale, the role of key features of the local atmospheric circulation on the origin and development of Tropical Temperate Troughs (TTTs) representing a major contribution to South African rainfall during austral summer. A cluster analysis applied on 1971–2000 ERA40 and WRF simulated daily outgoing longwave radiation reveals for the November–February season three coherent regimes characteristic of TTTs over the region. Analyses of WRF simulated TTTs suggest that their occurrence is primarily linked with mid-latitude westerly waves and their phasing. Ensemble experiments designed for the case of austral summer 1996/1997 allow to examine the reproducibility of TTT events. The results obtained illustrate the importance of westerly waves phasing regarding the persistence of rain-producing continental TTT events. Moreover, oceanic surface conditions prevailing over the Agulhas current regions of the South West Indian Ocean (SWIO) are also found to influence TTT persistence for regional experiments with an oceanic mixed layer, warmer sea surface temperatures being associated with increased moisture advection from the SWIO where latent heat release is enhanced, favoring baroclinic instability and thus sustaining convection activity locally.

Keywords

Regional modeling Tropical-temperate interactions Southern Africa climate 
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Notes

Acknowledgments

N. Vigaud would like to acknowledge the financial support of the University of Burgundy (Dijon, France) through the BQR2010-005 program. Calculations were performed using HPC resources from DSI-CCUB, University of Burgundy. WRF was provided by the University Corporation for Atmospheric Research (http://www.mmm.ucar.edu/wrfusers/download/getsource.html). ECMWF ERA40 re-analyses used in this study were obtained from ECMWF Meteorological Archival and Retrieval System (MARS) data server, GPCP rainfall estimates and WRC rain-gauges observation from the referring institutions.

References

  1. Adler R, Huffman G, Chang A, Ferraro R, Xie P, Janowiak J, Rudolf B, Schneider U, Curtis S, Bolvin D, Gruber A, Susskind J, Arkin P (2003) The version 2 Global Precipitation Climatology Project (GPCP) monthly precipitation analysis (1979-present). J Hydrometeor 4:1147–1167CrossRefGoogle Scholar
  2. Alexandru M, de Elia R, Laprise R, Separovic L, Biner S (2009) Sensitivity study of regional climate model simulations to large-scale nudging parameters. Mon Weather Rev 137:1666–1686CrossRefGoogle Scholar
  3. Anyah FS, RO (2007) Simulation of the intensity of Lake Victoria basin climate to lake surface temperatures. Theor Appl Meteor 79:55–69Google Scholar
  4. Castro C, Pielke R, Leoncini G (2005) Dynamical downscaling: assessment of value retained and added using regional atmospheric model system. J Geophys Res 110. doi: 10.1029/2004JDO04721
  5. Chen F, Dudhia J (2001) Coupling an advanced land-surface/hydrology model with the Penn State/NCAR MM5 modeling system. Part I: model description and implementation. Mon Weather Rev 129:569–585CrossRefGoogle Scholar
  6. Cheng X, Wallace J (2003) Regime analysis of the Northern Hemisphere winter-time 500 hPa height field: spatial patterns. J Atmos Sci 50:2674–2696CrossRefGoogle Scholar
  7. Cook C, Reason CJC, Hewitson B (2004) Wet and dry spells within particularly wet and dry summers in the South African summer rainfall region. Clim Res 26:17–31Google Scholar
  8. Cook K (2000) The south indian convergence zone and interrannual rainfall variability over southern Africa. J Clim 13:3789–3804Google Scholar
  9. Crétat J, Macron C, Pohl B, Richard Y (2011) Quantifying internal variability in a regional climate model: a case study for southern Africa. Clim Dyn. doi: 10.1007/s00382-011-1021-5
  10. Crétat J, Pohl B, Richard Y, Drobinski P (2012) Uncertainties in simulating regional climate of southern Africa: sensitivity to physical parametrizations using WRF. Clim Dyn 38:613–614. doi: 10.1007/s00382-011-1055-8 Google Scholar
  11. D’Abreton P (1992) The dynamics and energetics of tropical-temperate troughs over southern Africa. PhD Thesis, University of Witwatersrand, JohannesburgGoogle Scholar
  12. Douville H (2004) Relevance of soil moisture for seasonal atmospheric predictions: is it an initial value problem? Clim Dyn 22:429–446CrossRefGoogle Scholar
  13. Dudhia J (1989) Numerical study of convection observed during the winter experiment using a mesoscale two-dimensional model. J Atmos Sci 46:3077–3107CrossRefGoogle Scholar
  14. Dyer T (1979) Rainfall along the east coast of southern Africa, the southern oscillation and the latitude of the subtropical high pressure belt. Q J R Meteorol Soc 105:445–451CrossRefGoogle Scholar
  15. Fauchereau N, Pohl B, Reason C, Rouault M, Richard Y (2009) Recurrent daily OLR patterns in the southern Africa/southwest Indian Ocean region, implications for South African rainfall and teleconnections. Clim Dyn 32:575–591CrossRefGoogle Scholar
  16. Grell G, Dévényi D (2002) A generalized approach to parameterizing convection combining ensemble and data assimilation techniques. Geophys Res Lett. doi: 10.1029/2002GL015311
  17. Hansingo K, Reason C (2006) Sensitivity of the atmospheric response to sea-surface temperature forcing in the southwest Indian ocean: a regional climate modelling study. South Afr J Sci 102:137–143Google Scholar
  18. Harrison M (1984) A generalised classification of southern african summer rain-bearing synoptic systems. J Climatol 4:547–560CrossRefGoogle Scholar
  19. Harrison M (1986) A synoptic climatology of south African rainfall variations. PhD Thesis, University of Witwatersrand, JohannesburgGoogle Scholar
  20. Hewitson B, Reason C, Tennant W, Jack C, Mackellar N, Lennard C, Hansingo K, Walawege R, Mdoka M (2004) Dynamical modeling of the present and future climate system. Tech. Report to Water Research Commission 1154/1/04Google Scholar
  21. Hong S, Noh Y, Dudhia J (2006) A new vertical diffusion package with an explicit treatment of entrainment processes. Mon Weather Rev 134:2318–2341CrossRefGoogle Scholar
  22. Hudson D, Jones R (2002) Regional climate modeling simulations of present-day and future climates of southern Africa. Hadley Center Technical notes N39(42)Google Scholar
  23. Kgatuke M, Landman W, Beraki A, Mbedzi M (2008) The internal variability of RegCM3 over South Africa. Int J Climatol 28:505–520CrossRefGoogle Scholar
  24. Landmann W, Goddard L (2005) Predicting southern african summer rainfall using a combination of mos and perfect prognosis. Geophys Res Lett 32. doi: 10.1029/2005GL022910
  25. Liebmann B, Smith C (1996) Description of a complete (interpolated) outgoing longwave radiation dataset. Bull Am Met Soc 83:1631–1643Google Scholar
  26. Lindesay J (1988) South african rainfall, the southern oscillation and a southern hemisphere semi-annual cycle. J Climatol 8:17–30CrossRefGoogle Scholar
  27. Lo J-F, Yang Z, Pielke R (2008) Assessment of three dynamical climate downscaling methods using the Weather Regional Forecasting (WRF) model. J Geophys Res 113. doi: 10.1029/2007JD009216
  28. Lynch S (2003) Development of a RASTER database of annual, monthly and daily rainfall for southern Africa. Wat Res Com, Pretoria, pp 78Google Scholar
  29. Mason S (1995) Sea-surface temperatures-South African rainfall associations. Int J Climatol 15:119–135CrossRefGoogle Scholar
  30. Michelangeli P, Vautard R, Legras B (1995) Weather regime occurence and quasi-stationarity. J Atmos Sci 52:1237–1256CrossRefGoogle Scholar
  31. Moron V, Plaut G (2003) The impact of El Niño-southern oscillation upon weather regimes over Europe and the North Atlantic during Boreal winter. Int J Climatol 23:363–379CrossRefGoogle Scholar
  32. Morrison H, Thompson G, Tatarskii V (2009) Impact of cloud microphysics on the development of trailing stratiform precipitation in a simulated squall line: comparison of one- and two-moment schemes. Mon Weather Rev 137:991–1007CrossRefGoogle Scholar
  33. Mwaler E, Taubman S, Brown P, Iacono M, Clough S (1997) Radiative transfer for inhomogeneous atmosphere: RRTM, a validated correlated-k model for the long-wave. J Geophys Res 102:16,663–16,682Google Scholar
  34. New M, Washington R, Jack C, Hewitson B (2003) Sensitivity to southern African climate to soil-moisture. CLIVAR Exch Lett 8:45–47Google Scholar
  35. Nicholson SE, Kim J (1997) The relationship of the el-niño-southern oscillation to African rainfall. Int J Climatol 17:117–135CrossRefGoogle Scholar
  36. Ninomiya K (2008) Similarities and differences among the South Indian Ocean convergence zone, North American convergence zone, and other subtropical convergences zones simulated using an AGCM. J Met Soc Jpn 86:141–165CrossRefGoogle Scholar
  37. Peixoto, J, Oort, A (eds) (1992) Physics of southern African climate. Springer, Berlin, p 520Google Scholar
  38. Pohl B, Richard Y, Fauchereau N (2007) Influence of the Madden-Julian oscillation on Southern African summer rainfall. J Clim 20:4227–4242CrossRefGoogle Scholar
  39. Pohl B, Fauchereau N, Richard Y, Rouault M, Reason C (2009) Interactions between synoptic, intraseasonal and interannual convective variability over Southern Africa. Clim Dyn 33:1033–1050CrossRefGoogle Scholar
  40. Ratnam J, Behera S, Masumoto Y, Takahashi K, Yamagata T (2011) A simple regional coupled model experiment for summer-time climate simulation over southern Africa. Clim Dyn (Accepted)Google Scholar
  41. Reason CJC (2001) Evidence for the influence of the agulhas current on regional atmospheric circulation patterns. J Clim 14:2769–2778CrossRefGoogle Scholar
  42. Reason CJC, Allen AJ, Lindesay JA, Ansell TJ (2000) Enso and climatic signals across the Indian ocean basin in the global context: Part I, interannual composite patterns. Int J Climatol 20:1285–1327CrossRefGoogle Scholar
  43. Richard Y, Trzaska S, Roucou P, Rouault M (2000) Modification of the southern African rainfall variability/enso relationship since the late 1960s. Clim Dyn 16:883–895CrossRefGoogle Scholar
  44. Rockel B, Castro C, Pielke R, von Storch H, Leoncini G (2008) Dynamical downscaling: assessment of model system dependant retained and added variability for two different regional climate models. J Geophys Res. doi: 10.1029/2007JD0099461
  45. Shamarock W, Klemp J, Dudhia J, Gill D, Barker D, Duda M, Huang X, Wang W, Powers J (2008) A description of the advanced research WRF version 3. NCAR technical note NCAR/TN/u2013475+STRGoogle Scholar
  46. Tadross M, Gutowski JW, Hewitson B, Jack C, New M (2006) MM5 simulations of interannual change and the diurnal cycle of southern African regional climate. Theor Appl Climatol 86:63–80CrossRefGoogle Scholar
  47. Todd MC, Washington R (1999) Circulation anomalies associated with tropical-temperate troughs over southern Africa. Clim Dyn 15:937–951CrossRefGoogle Scholar
  48. Todd MC, Washington R (2004) Climate variability in central equatorial africa : influence from the Atlantic sector. Geophys Res Lett 31. doi: 10.1029/2004GLO20975
  49. Todd MC, Washington R, Palmer PI (2004) Water vapour transport associated with tropical-temperate trough systems over southern Africa and the southwest Indian ocean. J Clim 24:555–568CrossRefGoogle Scholar
  50. Trenberth K (1991) Storm tracks in the southern hemisphere. J Atmos Sci 48:2159–2178CrossRefGoogle Scholar
  51. Uppala S, Kallberg P, Simmons A, Andrae U, Fiorino M, Gibson J, Haseler J, Hernandez A, Kelly G, Li X, Onogi K, Saarinen S, Sokka N, Allan R, Anderson E, Arpe K, Balmaseda M, Beljaars A, den Berg LV (2005) The ERA-40 re-analysis. Q J R Meteorol Soc 131:2961–3012CrossRefGoogle Scholar
  52. Vigaud N, Richard Y, Rouault M, Fauchereau N (2007) Water vapour from the tropical Atlantic and summer rainfall in tropical southern Africa. Clim Dyn. doi: 10.1007/s00382-006-0186-9
  53. Vigaud N, Richard Y, Rouault M, Fauchereau N (2009) Moisture transport between the South Atlantic Ocean and southern Africa: relationship with summer rainfall and associated dynamics. Clim Dyn. doi: 10.1007/s00382-008-0377-7
  54. Walker N (1990) Links between south African summer rainfall and temperature variability of the argulhas and benguela current systems. J Geophys Res 95:3297–3319CrossRefGoogle Scholar
  55. Walker N, Lindesay J (1989) Preliminary observations of oceanic influences on the February–March 1988 floods in central South Africa. S Afr J Sci 85:164–169Google Scholar
  56. Washington MT, R. (1999) Tropical-temperate links in southern Africa and southwest Indian Ocean satellite-derived daily rainfall. Int J Climatol 19:1601–1616Google Scholar
  57. Widlansky M (2010) Climate dynamics of the South Pacific convergence zone and similarities with other subtropical convergence zones in the Southern Hemisphere. PhD Thesis, Georgia Institute of TechnologyGoogle Scholar

Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  1. 1.Centre de Recherches de ClimatologieUMR 6282 Biogéosciences CNRS/Université de BourgogneDijonFrance

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