Editorial Type:
Article
Article Type:
Research Article

Mid-Twenty-First-Century Changes in Extreme Events over Northern and Tropical Africa

Edward K. Vizy Department of Geological Sciences, Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas

Search for other papers by Edward K. Vizy in
Current site
Google Scholar
PubMed Close
and
Kerry H. Cook Department of Geological Sciences, Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas

Search for other papers by Kerry H. Cook in
Current site
Google Scholar
PubMed Close
Print Publication:
01 Sep 2012
DOI:
https://doi.org/10.1175/JCLI-D-11-00693.1
Page(s):
5748–5767
Restricted access

Abstract

Changes in rainfall and temperature extremes are predicted by many global climate models as a response to greenhouse gas increases, and such changes will have significant environmental and social impacts. A regional climate model is used to predict changes in extremes across tropical and northern Africa for 2041–60 under a midline emissions forcing scenario. Six indicators are examined, including annual extreme and daily diurnal temperature ranges, heat wave days, number of dry days, number of extreme wet days, and extreme wet day rainfall intensity. Confidence in the projections is evaluated by examining the ensemble spread and the validation of extreme events in the twentieth-century simulation.

Despite an increase in both daily minimum and maximum temperatures, diurnal temperature ranges decrease from West Africa to Ethiopia during spring and fall, over the Sahel during summer, and over the Congo basin during winter and spring. Diurnal temperature ranges increase over the Horn of Africa during boreal winter and over Kenya and Tanzania during boreal summer. The number of heat wave days increases north of 8°N with the largest increase (60–120 days) over the western Sahel. The number of dry days decreases over the Congo and the central Sahel but increases over East Africa, the latter associated with a reduction in the springtime long rains. The number of extreme wet rainfall days is projected to increase over West Africa, the Sahel, and the Ethiopian Highlands but decrease over the Congo. The predicted changes in extreme wet rainfall intensity are highly regional.

Corresponding author address: Edward K. Vizy, Jackson School of Geosciences, The University of Texas at Austin, 1 University Station C1100, Austin, TX 78712. E-mail: ned@jsg.utexas.edu

Abstract

Changes in rainfall and temperature extremes are predicted by many global climate models as a response to greenhouse gas increases, and such changes will have significant environmental and social impacts. A regional climate model is used to predict changes in extremes across tropical and northern Africa for 2041–60 under a midline emissions forcing scenario. Six indicators are examined, including annual extreme and daily diurnal temperature ranges, heat wave days, number of dry days, number of extreme wet days, and extreme wet day rainfall intensity. Confidence in the projections is evaluated by examining the ensemble spread and the validation of extreme events in the twentieth-century simulation.

Despite an increase in both daily minimum and maximum temperatures, diurnal temperature ranges decrease from West Africa to Ethiopia during spring and fall, over the Sahel during summer, and over the Congo basin during winter and spring. Diurnal temperature ranges increase over the Horn of Africa during boreal winter and over Kenya and Tanzania during boreal summer. The number of heat wave days increases north of 8°N with the largest increase (60–120 days) over the western Sahel. The number of dry days decreases over the Congo and the central Sahel but increases over East Africa, the latter associated with a reduction in the springtime long rains. The number of extreme wet rainfall days is projected to increase over West Africa, the Sahel, and the Ethiopian Highlands but decrease over the Congo. The predicted changes in extreme wet rainfall intensity are highly regional.

Corresponding author address: Edward K. Vizy, Jackson School of Geosciences, The University of Texas at Austin, 1 University Station C1100, Austin, TX 78712. E-mail: ned@jsg.utexas.edu
Save
Cover Journal of Climate
Journal of Climate

  • Betts, A. K., M. Zhao, P. A. Dirmeyer, and A. C. Beljaars, 2006: Comparison of ERA40 and NCEP/DOE near-surface data sets with other ISLSCP-II data sets. J. Geophys. Res., 111, D22S04, doi:10.1029/2006JD007174.

    • Search Google Scholar
    • Export Citation

  • Chen, F., and J. Dudhia, 2001: Coupling an advanced land-surface/ hydrology model with the Penn State/NCAR MM5 modeling system. Part I: Model description and implementation. Mon. Wea. Rev., 129, 569–585.

    • Search Google Scholar
    • Export Citation

  • Chen, S.-H., and W.-Y. Sun, 2002: A one-dimensional time dependent cloud model. J. Meteor. Soc. Japan, 80, 99–118.

  • Cook, K. H., and E. K. Vizy, 2012: Impact of climate change on mid-twenty-first century growing seasons in Africa. Climate Dyn., doi:10.1007/s00382-012-1324-1, in press.

    • Search Google Scholar
    • Export Citation

  • Dudhia, J., 1989: Numerical study of convection observed during the winter monsoon experiment using a mesoscale two-dimensional model. J. Atmos. Sci., 46, 3077–3107.

    • Search Google Scholar
    • Export Citation

  • Frich, P., L. V. Alexander, P. Della-Marta, B. Gleason, M. Haylock, A. M. G. Klien Tank, and T. Peterson, 2002: Observed coherent changes in climatic extremes during the second half of the twentieth century. Climate Res., 19, 193–212.

    • Search Google Scholar
    • Export Citation

  • Hagos, S. M., and K. H. Cook, 2007: Dynamics of the West African monsoon jump. J. Climate, 20, 5264–5284.

  • Hong, S.-Y., Y. Noh, and J. Dudhia, 2006: A new vertical diffusion package with an explicit treatment of entrainment processes. Mon. Wea. Rev., 134, 2318–2341.

    • Search Google Scholar
    • Export Citation

  • Kain, J. S., 2004: The Kain–Fritsch convective parameterization: An update. J. Appl. Meteor., 43, 170–181.

  • Kalkstein, L. S., and K. E. Smoyer, 1993: The impact of climate change on human health: Some international implications. Experimentia, 49, 44–64.

    • Search Google Scholar
    • Export Citation

  • Kanamitsu, M., W. Ebisuzaki, J. Woollen, S. K. Yang, J. J. Hnilo, M. Fiorino, and G. L. Potter, 2002: NCEP-DOE AMIP-II Reanalysis (R2). Bull. Amer. Meteor. Soc., 83, 1631–1643.

    • Search Google Scholar
    • Export Citation

  • Kharin, V. V., F. W. Zwiers, X. Zhang, and G. C. Hegerl, 2007: Changes in temperature and precipitation extremes in the IPCC ensemble of global model simulations. J. Climate, 20, 1419–1444.

    • Search Google Scholar
    • Export Citation

  • Klein Tank, A. M. G., F. W. Zwiers, and X. Zhang, 2009: Climate data and monitoring. WCDMP-72, WMO-TD 1500, 56 pp.

  • Meehl, G. A., and Coauthors, 2007: Global climate projections. Climate Change 2007: The Physical Science Basis, S. Solomon et al., Eds., Cambridge University Press, 747–845.

  • Mlawer, E. J., S. J. Taubman, P. D. Brown, M. J. Iacono, and S. A. Clough, 1997: Radiative transfer for inhomogeneous atmosphere: RRTM, a validated correlated-k model for the longwave. J. Geophys. Res., 102 (D14), 16 663–16 682.

    • Search Google Scholar
    • Export Citation

  • Moore, D. S., and G. P. McCabe, 1993: Introduction to the Practice of Statistics. W. H. Freeman and Company, 854 pp.

  • Mutai, C. C., M. N. Ward, and A. W. Colman, 1998: Toward the prediction of the East African short rains passed on sea surface temperature and atmosphere coupling. Int. J. Climatol., 18, 975–997.

    • Search Google Scholar
    • Export Citation

  • Paeth, H., and H.-P. Thamm, 2007: Regional modeling of future African climate north of 15°S including greenhouse warming and land degradation. Climatic Change, 83, 401–427.

    • Search Google Scholar
    • Export Citation

  • Paeth, H., K. Born, R. Girmes, R. Podzun, and D. Jacob, 2009: Regional climate change in tropical and northern Africa due to greenhouse forcing and land use changes. J. Climate, 22, 114–132.

    • Search Google Scholar
    • Export Citation

  • Paeth, H., and Coauthors, 2011: Progress in regional downscaling of West African precipitation. Atmos. Sci. Lett., 12, 75–82.

  • Patricola, C. M., and K. H. Cook, 2007: Dynamics of the West African monsoon under mid-Holocene precessional forcing: Regional climate model simulations. J. Climate, 20, 694–716.

    • Search Google Scholar
    • Export Citation

  • Patricola, C. M., and K. H. Cook, 2010: Northern African climate at the end of the twenty-first century: An integrated application of regional and global climate models. Climate Dyn., 35, 193–212.

    • Search Google Scholar
    • Export Citation

  • Patricola, C. M., and K. H. Cook, 2011: Sub-Saharan Northern African climate at the end of the twenty-first century: Forcing factors and climate change processes. Climate Dyn., 37, 1165–1188.

    • Search Google Scholar
    • Export Citation

  • Robinson, P. J., 2001: On the definition of a heat wave. J. Appl. Meteor., 40, 762–775.

  • Shongwe, M. E., G. Jan Van Oldenborgh, and B. Van Den Hurk, 2011: Projected changes in mean and extreme precipitation in Africa under global warming. Part II: East Africa. J. Climate, 24, 3718–3733.

    • Search Google Scholar
    • Export Citation

  • Skamarock, W. C., J. B. Klemp, J. Dudhia, D. O. Gill, D. M. Barker, W. Wang, and J. G. Powers, 2005: A description of the advanced research WRF version 2. NCAR/TN-408+STR, 88 pp. [Available from NCAR Information Services, P.O. Box 3000, Boulder, CO 80307.]

  • Steadman, R. G., 1979: The assessment of sultriness. Part I: A temperature humidity index based on human physiology and clothing science. J. Appl. Meteor., 18, 861–873.

    • Search Google Scholar
    • Export Citation

  • Steadman, R. G., 1984: A universal scale of apparent temperature. J. Climate Appl. Meteor., 23, 1674–1687.

  • Sylla, M. B., A. T. Gaye, G. S. Jenkins, J. S. Pal, and F. Giorgi, 2010: Consistency of projected drought over the Sahel with changes in monsoon circulation and extremes in a regional climate model projections. J. Geophys. Res., 115, D16108, doi:10.1029/2009JD012983.

    • Search Google Scholar
    • Export Citation

  • Tebaldi, C., K. Hayhoe, J. M. Arblaster, and G. A. Meehl, 2006: Going to the extremes: An intercomparison of model-simulated historical and future changes in extreme events. Climatic Change, 79, 185–211.

    • Search Google Scholar
    • Export Citation

  • Vigaud, N., P. Roucou, B. Fontaine, S. Sijikumar, and S. Tyteca, 2011: WRF/ARPEGE-CLIMAT simulated climate trends over West Africa. Climate Dyn., 36, 925–944.

    • Search Google Scholar
    • Export Citation

  • Vizy, E. K., and K. H. Cook, 2002: Development and application of a mesoscale climate model for the tropics: Influence of sea surface temperature anomalies on the West African monsoon. J. Geophys. Res., 107, 4023, doi:10.1029/2001JD000686.

    • Search Google Scholar
    • Export Citation

  • Vizy, E. K., and K. H. Cook, 2003: Connections between the summer East African and Indian rainfall regimes. J. Geophys. Res., 108, 4510, doi:10.1029/2003JD003452.

    • Search Google Scholar
    • Export Citation

  • Vose, R. S., D. R. Easterling, and B. Gleason, 2005: Maximum and minimum temperature trends for the globe: An update through 2004. Geophys. Res. Lett., 32, L23822, doi:10.1029/2005GL024379.

    • Search Google Scholar
    • Export Citation

  • Zhang, X., and F. Yang, 2004: RClimDex (1.0) user manual. Climate Research Branch, Environment Canada, 23 pp. [Available online at http://precis.metoffice.com/Tutorials/RClimDexUserManual.doc.]

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 892 271 22
PDF Downloads 618 182 22