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Seasonal variation of the ITCZ and its characteristics over central Africa

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Abstract

We investigated the seasonal march of the Intertropical Convergence Zone (ITCZ) shown by the 22 coupled general circulation models of the 20th Century Climate in Coupled Models experiment in seven regions (Africa, Indian Ocean, western Pacific, central Pacific, eastern Pacific, South America, and Atlantic Ocean). Inter-model differences in the seasonal march of the ITCZ over Africa (10–40°E) were significantly smaller than those over other regions. This finding indicates that the seasonal march of the ITCZ over Africa is insensitive to differences in model physics and resolution and suggests that the seasonal march of the African ITCZ is controlled by robust and simple mechanisms. Motivated by this result, we tried to understand the process of the seasonal march of the ITCZ over central Africa (15–30°E) based on an analysis of ERA-40 data. The analysis results revealed the following features of the ITCZ in this region: (1) The ITCZ itself produces large convective available potential energy that generates deep convection. (2) The abundant water vapor within the ITCZ is maintained by horizontal moisture flux. (3) Outside but near the ITCZ, shallow convection exists and may act to pre-moisten deep convection in spring and autumn. (4) The seasonal change of the ITCZ is preceded by that of the vertical moist instability in the lower free atmosphere caused by the seasonal change in insolation.

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References

  • Adler RF et al (2003) The Version-2 Global Precipitation Climatology Project (GPCP) monthly precipitation analysis (1979–present). J Hydrometeorol 4:1147–1167

    Article  Google Scholar 

  • Betts AK (1986) A new convective adjustment scheme. Part I: observational and theoretical basis. Q J R Meteorol Soc 112:677–691

    Google Scholar 

  • Biasutti M, Battisti DS, Sarachik ES (2003) The annual cycle over the tropical Atlantic, South America, and Africa. J Clim 16:2491–2508

    Article  Google Scholar 

  • Biasutti M, Battisti DS, Sarachik ES (2004) Mechanisms controlling the annual cycle of precipitation in the tropical Atlantic sector in an atmospheric GCM. J Clim 17:4708–4723

    Article  Google Scholar 

  • Biasutti M, Sobel AH, Kushnir Y (2006) AGCM precipitation biases in the tropical Atlantic. J Clim 19:935–958

    Article  Google Scholar 

  • Del Genio AD, Yao MS (1993) Efficient cumulus parameterization for long-term climate studies: the GISS scheme. In: Emanuel KA, Raymond DJ (eds) The representation of cumulus convection in numerical models. Meteor Monogr No. 46. Amer Meteor Soc, Boston, pp 181–184

  • Emanuel KA (1991) A scheme for representing cumulus convection in large-scale models. J Atmos Sci 48:2313–2335

    Article  Google Scholar 

  • Grandpeix JY, Phillips V, Tailleux R (2004) Improved mixing representation in Emanuel's convection scheme. Q J R Meteorol Soc 130:3207–3222

    Article  Google Scholar 

  • Gregory D, Rowntree PR (1990) A mass flux convection scheme with representation of cloud ensemble characteristics and stability-dependent closure. Mon Weather Rev 118:1483–1506

    Article  Google Scholar 

  • Hack JJ (1994) Parameterization of moist convection in the National Center for Atmospheric Research community climate model (CCM2). J Geophys Res 99:5551–5568

    Article  Google Scholar 

  • Hartmann DL (1994) Global physical climatology. Academic Press, San Diego, p 411

  • Kalnay E et al (1996) The NCEP/NCAR 40-year reanalysis project. Bull Am Meteorol Soc 77:437–471

    Article  Google Scholar 

  • Lin JL (2007) The double-ITCZ problem in IPCC AR4 coupled GCMs: ocean–atmosphere feedback analysis. J Clim 20:4497–4525

    Article  Google Scholar 

  • McGregor GR, Nieuwolt S (1998) Tropical climatology, 2nd edn. Wiley, Chichester, p 339

    Google Scholar 

  • Meehl GA, Covey C, Delworth T, Latif M, McAvaney B, Mitchell JFB, Stouffer RJ, Taylor KE (2007) The WCRP CMIP3 multimodel dataset: a new era in climate change research. Bull Am Meteorol Soc 88:1383–1394

    Article  Google Scholar 

  • Moorthi S, Suarez MJ (1992) Relaxed Arakawa–Schubert: a parameterization of moist convection for general circulation models. Mon Weather Rev 120:978–1002

    Article  Google Scholar 

  • Nicholson SE (1986) The spatial coherence of African rainfall anomalies: interhemispheric teleconnections. J Clim Appl Meteorol 25:1365–1381

    Article  Google Scholar 

  • Nicholson SE (2009) A revised picture of the structure of the “monsoon” and land ITCZ over West Africa. Clim Dyn 32:1155–1171

    Article  Google Scholar 

  • Nicholson SE, Grist JP (2003) The seasonal evolution of the atmospheric circulation over West Africa and Equatorial Africa. J Clim 16:1013–1030

    Article  Google Scholar 

  • Ninomiya K, Nishimura T, Ohfuchi W, Suzuki T, Matsumura S (2002) Feature of the Baiu front simulated in an AGCM (T42L52). J Meteorol Soc Jpn 80:697–716

    Article  Google Scholar 

  • Nordeng TE (1994) Extended versions of the convective parameterization scheme at ECMWF and their impact on the mean and transient activity of the model in the tropics. Technical Memorandum No. 206. European Centre for Medium-Range Weather Forecasts, Reading, p 41

  • Pan DM, Randall DA (1998) A cumulus parameterization with a prognostic closure. Q J R Meteorol Soc 124:949–981

    Google Scholar 

  • Suzuki T, Ninomiya K, Emori S (2008) The impact of cumulus suppression on the Baiu front simulated by an AGCM. J Meteorol Soc Jpn 86:119–140

    Article  Google Scholar 

  • Tiedtke M (1989) A comprehensive mass flux scheme for cumulus parameterization in large-scale models. Mon Weather Rev 117:1779–1800

    Article  Google Scholar 

  • Uppala SM et al (2005) The ERA-40 re-analysis. Q J R Meteorol Soc 131:2961–3012

    Article  Google Scholar 

  • Vigaud N, Richard Y, Rouault M, Fauchereau N (2007) Water vapour transport from the tropical Atlantic and summer rainfall in tropical southern Africa. Clim Dyn 28:113–123

    Article  Google Scholar 

  • Vigaud N, Richard Y, Rouault M, Fauchereau N (2009) Moisture transport between the South Atlantic Ocean and southern Africa: relationships with summer rainfall and associated dynamics. Clim Dyn 32:113–123

    Article  Google Scholar 

  • Waliser DE (2003) Inter tropical convergence zones. In: Holton JR, Curry JA, Pyle JA (eds) Encyclopedia of atmospheric sciences. Academic Press, London, pp 2325–2334

  • Waliser DE, Gautier C (1993) A satellite-derived climatology of the ITCZ. J Clim 6:2162–2174

    Article  Google Scholar 

  • Zhang GJ, McFarlane NA (1995) Sensitivity of climate simulations to the parameterization of cumulus convection in the Canadian Climate Centre General Circulation Model. Atmos-Ocean 33:407–446

    Google Scholar 

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Acknowledgments

The author thanks Dr. Kozo Nimoniya for his useful comments. This work has been supported by the Global Environment Research Fund (S-5-2) of the Ministry of the Environment, Japan. The Program for Climate Model Diagnosis and Intercomparison (PCMDI) and the WCRP’s Working Group on Coupled Modelling (WGCM) are also acknowledged for their roles in making the WCRP CMIP3 multi-model dataset available. Support for this dataset was provided by the Office of Science, U.S. Department of Energy.

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  1. Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology, 3173-25 Showa-machi, Kanazawa-ku, Yokohama, Kanagawa, 236-0001, Japan

    Tsuneaki Suzuki

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Correspondence to Tsuneaki Suzuki.

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Suzuki, T. Seasonal variation of the ITCZ and its characteristics over central Africa. Theor Appl Climatol 103, 39–60 (2011). https://doi.org/10.1007/s00704-010-0276-9

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  • DOI: https://doi.org/10.1007/s00704-010-0276-9

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