• Collins, W. D., and Coauthors, 2006: The Community Climate System Model, version 3 (CCSM3). J. Climate, 19, 21222143.

  • Cook, K. H., 1999: Generation of the African easterly jet and its role in determining West African precipitation. J. Climate, 12, 11651184.

    • Search Google Scholar
    • Export Citation
  • Gent, P. R., and Coauthors, 2011: The Community Climate System Model, version 4. J. Climate, 24, 49734991.

  • Grodsky, S. A., , J. A. Carton, , and S. Nigam, 2003: Near surface westerly wind jet in the Atlantic ITCZ. Geophys. Res. Lett., 30, 2009, doi:10.1029/2003GL017867.

    • Search Google Scholar
    • Export Citation
  • Gutzler, D. S., and Coauthors, 2009: Simulations of the North American monsoon: NAMAP2. J. Climate, 22, 67166740.

  • Hagos, S. M., , and K. H. Cook, 2007: Dynamics of the West African monsoon jump. J. Climate, 20, 52645284.

  • Huffman, G. J., and Coauthors, 2007: The TRMM multi-satellite precipitation analysis: Quasi-global, multi-year, combined-sensor precipitation estimates at fine scale. J. Hydrometeor., 8, 3855.

    • Search Google Scholar
    • Export Citation
  • Meehl, G. A., , and J. M. Arblaster, 1998: The Asian–Australian monsoon and El Niño–Southern Oscillation in the NCAR climate system model. J. Climate, 11, 13561385.

    • Search Google Scholar
    • Export Citation
  • Meehl, G. A., , J. M. Arblaster, , D. M. Lawrence, , A. Seth, , E. K. Schneider, , B. P. Kirtman, , and D. Min, 2006: Monsoon regimes in the CCSM3. J. Climate, 19, 24822495.

    • Search Google Scholar
    • Export Citation
  • Meehl, G. A., , J. M. Arblaster, , J. Caron, , H. Annamalai, , M. Jochum, , A. Chakraborty, , and R. Murtugudde, 2012: Monsoon regimes and processes in CCSM4. Part I: The Asian–Australian monsoon. J. Climate, 25, 25832608.

    • Search Google Scholar
    • Export Citation
  • Pu, B., , and K. H. Cook, 2010: Dynamics of the West African westerly jet. J. Climate, 23, 62636276.

  • Rayner, N. A., , D. E. Parker, , E. B. Horton, , C. K. Folland, , L. V. Alexander, , D. P. Rowell, , E. C. Kent, , and A. Kaplan, 2003: Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century. J. Geophys. Res., 108, 4407, doi:10.1029/2002JD002670.

    • Search Google Scholar
    • Export Citation
  • Riddle, E. E., , and K. H. Cook, 2008: Abrupt rainfall transitions over the Greater Horn of Africa: Observations and regional model simulations. J. Geophys. Res., 113, D15109, doi:10.1029/2007JD009202.

    • Search Google Scholar
    • Export Citation
  • Rowell, D. P., , and J. R. Milford, 1993: On the generation of African squall lines. J. Climate, 6, 11811193.

  • Simmons, A., , S. Uppla, , D. De, , and S. Kobayashi, 2006: ERA-Interim: New ECMWF reanalysis products from 1989 onwards. ECMWF Newsletter, No. 110, ECMWF, Reading, United Kingdom, 25–35.

    • Search Google Scholar
    • Export Citation
  • Sultan, B., , and S. Janicot, 2003: The West African monsoon dynamics. Part II: The preonset and onset of the summer monsoon. J. Climate, 16, 34073427.

    • Search Google Scholar
    • Export Citation
  • Vera, C., and Coauthors, 2006: Toward a unified view of the American monsoon systems. J. Climate, 19, 49775000.

  • Xie, P., , and P. Arkin, 1996: Analyses of global monthly precipitation using gauge observations, satellite estimates, and numerical model predictions. J. Climate, 9, 840858.

    • Search Google Scholar
    • Export Citation
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Monsoon Regimes and Processes in CCSM4. Part II: African and American Monsoon Systems

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  • 1 The University of Texas at Austin, Austin, Texas
  • | 2 National Center for Atmospheric Research,* Boulder, Colorado
  • | 3 National Center for Atmospheric Research,* Boulder, Colorado, and CAWCR, Bureau of Meteorology, Melbourne, Victoria, Australia
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Abstract

This is the second part of a two part series studying simulation characteristics of the Community Climate System Model, version 4 (CCSM4) for various monsoon regimes around the global tropics. Here, the West African, East African, North American, and South American monsoons are documented in CCSM4. Comparisons are made to an Atmospheric Model Intercomparison Project (AMIP) simulation of the atmospheric component in CCSM4 (CAM4), to deduce differences in the monsoon simulations run with observed SSTs and with ocean–atmosphere coupling. These simulations are also compared to a previous version of the coupled model (CCSM3) to evaluate progress. In most, but not all instances, monsoon rainfall is too heavy in the uncoupled AMIP run with the Community Atmosphere Model, version 4 (CAM4), and monsoon rainfall amounts are generally better simulated with ocean coupling in CCSM4. Some aspects of the monsoon simulations are improved in CCSM4 compared to CCSM3. Early-season rainfall in the West African monsoon is better simulated in CAM4 than in CCSM4 presumably because of the specification of SSTs in the Gulf of Guinea, but the Sahel rainfall season is captured better in CCSM4 as are the African easterly jet and the tropical easterly jet. Improvements in the simulation of the Sahel rainy season (July, August, and September) in CCSM4 compared with CCSM3 are significant, but problems remain in the simulation of the early season (May and June) in association with the misrepresentation of eastern Atlantic (Gulf of Guinea) SSTs. Precipitation distributions and the southwesterly low-level inflow in the North American monsoon are improved in CCSM4 compared to CCSM3. Both CAM4 and CCSM4 reproduce the seasonal evolution of rainfall over the South American monsoon region, but the location of maximum rainfall is misplaced to the northeast in both models.

The National Center for Atmospheric Research is sponsored by the National Science Foundation.

Corresponding author address: Dr. Kerry H. Cook, Dept. of Geological Sciences, Jackson School of Geosciences, C1100 University Station, The University of Texas at Austin, Austin, TX 78712. E-mail: kc@jsg.utexas.edu

This article is included in the CCSM4 Special Collection.

Abstract

This is the second part of a two part series studying simulation characteristics of the Community Climate System Model, version 4 (CCSM4) for various monsoon regimes around the global tropics. Here, the West African, East African, North American, and South American monsoons are documented in CCSM4. Comparisons are made to an Atmospheric Model Intercomparison Project (AMIP) simulation of the atmospheric component in CCSM4 (CAM4), to deduce differences in the monsoon simulations run with observed SSTs and with ocean–atmosphere coupling. These simulations are also compared to a previous version of the coupled model (CCSM3) to evaluate progress. In most, but not all instances, monsoon rainfall is too heavy in the uncoupled AMIP run with the Community Atmosphere Model, version 4 (CAM4), and monsoon rainfall amounts are generally better simulated with ocean coupling in CCSM4. Some aspects of the monsoon simulations are improved in CCSM4 compared to CCSM3. Early-season rainfall in the West African monsoon is better simulated in CAM4 than in CCSM4 presumably because of the specification of SSTs in the Gulf of Guinea, but the Sahel rainfall season is captured better in CCSM4 as are the African easterly jet and the tropical easterly jet. Improvements in the simulation of the Sahel rainy season (July, August, and September) in CCSM4 compared with CCSM3 are significant, but problems remain in the simulation of the early season (May and June) in association with the misrepresentation of eastern Atlantic (Gulf of Guinea) SSTs. Precipitation distributions and the southwesterly low-level inflow in the North American monsoon are improved in CCSM4 compared to CCSM3. Both CAM4 and CCSM4 reproduce the seasonal evolution of rainfall over the South American monsoon region, but the location of maximum rainfall is misplaced to the northeast in both models.

The National Center for Atmospheric Research is sponsored by the National Science Foundation.

Corresponding author address: Dr. Kerry H. Cook, Dept. of Geological Sciences, Jackson School of Geosciences, C1100 University Station, The University of Texas at Austin, Austin, TX 78712. E-mail: kc@jsg.utexas.edu

This article is included in the CCSM4 Special Collection.

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