Dynamic Downscaling of Seasonal Simulations over South America

Vasubandhu Misra Center for Ocean–Land–Atmosphere Studies, Institute of Global Environment and Society, Inc., Calverton, Maryland

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Paul A. Dirmeyer Center for Ocean–Land–Atmosphere Studies, Institute of Global Environment and Society, Inc., Calverton, Maryland

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Ben P. Kirtman Center for Ocean–Land–Atmosphere Studies, Institute of Global Environment and Society, Inc., Calverton, Maryland

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Abstract

In this paper multiple atmospheric global circulation model (AGCM) integrations at T42 spectral truncation and prescribed sea surface temperature were used to drive regional spectral model (RSM) simulations at 80-km resolution for the austral summer season (January–February–March). Relative to the AGCM, the RSM improves the ensemble mean simulation of precipitation and the lower- and upper-level tropospheric circulation over both tropical and subtropical South America and the neighboring ocean basins. It is also seen that the RSM exacerbates the dry bias over the northern tip of South America and the Nordeste region, and perpetuates the erroneous split intertropical convergence zone (ITCZ) over both the Pacific and Atlantic Ocean basins from the AGCM. The RSM at 80-km horizontal resolution is able to reasonably resolve the Altiplano plateau. This led to an improvement in the mean precipitation over the plateau. The improved resolution orography in the RSM did not substantially change the predictability of the precipitation, surface fluxes, or upper- and lower-level winds in the vicinity of the Andes Mountains from the AGCM. In spite of identical convective and land surface parameterization schemes, the diagnostic quantities, such as precipitation and surface fluxes, show significant differences in the intramodel variability over oceans and certain parts of the Amazon River basin (ARB). However, the prognostic variables of the models exhibit relatively similar model noise structures and magnitude. This suggests that the model physics are in large part responsible for the divergence of the solutions in the two models. However, the surface temperature and fluxes from the land surface scheme of the model [Simplified Simple Biosphere scheme (SSiB)] display comparable intramodel variability, except over certain parts of ARB in the two models. This suggests a certain resilience of predictability in SSiB (over the chosen domain of study) to variations in horizontal resolution. It is seen in this study that the summer precipitation over tropical and subtropical South America is highly unpredictable in both models.

Corresponding author address: Dr. Vasubandhu Misra, Center for Ocean–Land–Atmosphere Studies, Institute for Global Environment and Society, Inc., 4041 Powder Mill Road, Suite 302, Calverton, MD 20705. Email: misra@cola.iges.org

Abstract

In this paper multiple atmospheric global circulation model (AGCM) integrations at T42 spectral truncation and prescribed sea surface temperature were used to drive regional spectral model (RSM) simulations at 80-km resolution for the austral summer season (January–February–March). Relative to the AGCM, the RSM improves the ensemble mean simulation of precipitation and the lower- and upper-level tropospheric circulation over both tropical and subtropical South America and the neighboring ocean basins. It is also seen that the RSM exacerbates the dry bias over the northern tip of South America and the Nordeste region, and perpetuates the erroneous split intertropical convergence zone (ITCZ) over both the Pacific and Atlantic Ocean basins from the AGCM. The RSM at 80-km horizontal resolution is able to reasonably resolve the Altiplano plateau. This led to an improvement in the mean precipitation over the plateau. The improved resolution orography in the RSM did not substantially change the predictability of the precipitation, surface fluxes, or upper- and lower-level winds in the vicinity of the Andes Mountains from the AGCM. In spite of identical convective and land surface parameterization schemes, the diagnostic quantities, such as precipitation and surface fluxes, show significant differences in the intramodel variability over oceans and certain parts of the Amazon River basin (ARB). However, the prognostic variables of the models exhibit relatively similar model noise structures and magnitude. This suggests that the model physics are in large part responsible for the divergence of the solutions in the two models. However, the surface temperature and fluxes from the land surface scheme of the model [Simplified Simple Biosphere scheme (SSiB)] display comparable intramodel variability, except over certain parts of ARB in the two models. This suggests a certain resilience of predictability in SSiB (over the chosen domain of study) to variations in horizontal resolution. It is seen in this study that the summer precipitation over tropical and subtropical South America is highly unpredictable in both models.

Corresponding author address: Dr. Vasubandhu Misra, Center for Ocean–Land–Atmosphere Studies, Institute for Global Environment and Society, Inc., 4041 Powder Mill Road, Suite 302, Calverton, MD 20705. Email: misra@cola.iges.org

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  • Alpert, J. C., M. Kanamitsu, P. M. Caplan, J. G. Sela, G. H. White, and E. Kalnay, 1988: Mountain induced gravity drag parameterization in the NMC medium-range model. Preprints, Eighth Conf. on Numerical Weather Prediction, Baltimore, MD, Amer. Meteor. Soc., 726–733.

    • Search Google Scholar
    • Export Citation
  • Chou, M-D., M. J. Suarez, C-H. Ho, M. M-H. Yan, and K-T. Lee, 1998: Parameterizations for cloud overlapping and shortwave single-scattering properties for use in general circulation and cloud ensemble models. J. Climate, 11 , 202214.

    • Search Google Scholar
    • Export Citation
  • Chou, S. C., A. M. B. Nunes, and I. F. A. Cavalcanti, 2000: Extended range forecasts over South America using the regional eta model. J. Geophys. Res., 105 , 1014710160.

    • Search Google Scholar
    • Export Citation
  • Davies, R., 1982: Documentation of the solar radiation parameterization in the GLAS climate model. NASA Tech. Memo. 83961, 57 pp.

  • Dirmeyer, P. A., and F. J. Zeng, 1997: A two dimensional implementation of the Simple Biosphere (SiB) model. COLA Tech. Rep. 48, 30 pp. [Available from COLA, 4041 Powder Mill Road, Suite 302, Calverton, MD 20705.].

    • Search Google Scholar
    • Export Citation
  • Dirmeyer, P. A., and F. J. Zeng, 1999: Precipitation infiltration in the simplified SiB land surface scheme. J. Meteor. Soc. Japan, 77 , 291303.

    • Search Google Scholar
    • Export Citation
  • Dirmeyer, P. A., F. J. Zeng, A. Ducharne, J. C. Morrill, and R. D. Koster, 2000: The sensitivity of surface fluxes to soil water content in three land surface schemes. J. Hydrometeor., 1 , 121134.

    • Search Google Scholar
    • Export Citation
  • Douglas, M. W., N. Nicolini, and C. Saulo, 1998: Observational evidences of a low level jet east of the Andes during January–March 1998. Meteorologica, 3 , 6372.

    • Search Google Scholar
    • Export Citation
  • Fels, S. B., and M. D. Schwarzkopf, 1975: The simplified exchange approximation: A new method for radiative transfer calculations. J. Atmos. Sci., 32 , 14751488.

    • Search Google Scholar
    • Export Citation
  • Fennessy, M. J., and J. Shukla, 2000: Seasonal prediction over North America with a regional model nested in a global model. J. Climate, 13 , 20652627.

    • Search Google Scholar
    • Export Citation
  • Figueroa, S. N., P. Satyamurty, and P. L. S. Dias, 1995: Simulations of the summer circulation over the South American region with an eta coordinate model. J. Atmos. Sci., 52 , 15731584.

    • Search Google Scholar
    • Export Citation
  • Garreaud, R. D., 1999: Multiscale analysis of the summertime precipitation over the central Andes. J. Climate, 12 , 901921.

  • Giorgi, F., 1990: Simulation of regional climate using a limited area model nested in a general circulation model. J. Climate, 3 , 941963.

    • Search Google Scholar
    • Export Citation
  • Giorgi, F., and X. Bi, 2000: A study of internal variability of a regional climate model. J. Geophys. Res., 105 , 2950329521.

  • Harshvardhan, R. Davies, D. A. Randall, and T. G. Corsetti, 1987: A fast radiation parameterization for atmospheric circulation models. J. Geophys. Res., 92 (D1) 10091016.

    • Search Google Scholar
    • Export Citation
  • Hong, S-Y., and H-L. Pan, 1996: Nonlocal boundary layer vertical diffusion in a medium range forecast model. Mon. Wea. Rev., 124 , 23222339.

    • Search Google Scholar
    • Export Citation
  • Janowiak, J. E., and P. Xie, 1999: CAMS–OPI: A global satellite–rain gauge merged product for real-time precipitation monitoring applications. J. Climate, 12 , 33353342.

    • Search Google Scholar
    • Export Citation
  • Ji, Y., and A. D. Vernekar, 1997: Simulation of the Asian summer monsoons of 1987 and 1988 with a regional model nested in a global GCM. J. Climate, 10 , 19651979.

    • Search Google Scholar
    • Export Citation
  • Juang, H-M., and M. Kanamitsu, 1994: The NMC nested regional spectral model. Mon. Wea. Rev., 122 , 326.

  • Juang, H-M., S-Y. Hong, and M. Kanamitsu, 1997: The NCEP regional spectral model: An update. Bull. Amer. Meteor. Soc., 78 , 21252143.

  • Kiehl, J. T., J. J. Hack, G. Bonan, B. A. Boville, D. L. Williamson, and P. J. Rasch, 1998: The National Center for Atmospheric Research Community Climate Model: CCM3. J. Climate, 11 , 11311149.

    • Search Google Scholar
    • Export Citation
  • Kinter, J. L,, and Coauthors. 1997: The COLA Atmosphere–Biosphere General Circulation Model. Vol. 1: Formulation. COLA Tech. Rep. 51, 44 pp. [Available from COLA, 4041 Powder Mill Road, Suite 302, Calverton, MD 20705.].

    • Search Google Scholar
    • Export Citation
  • Kirtman, B. P., D. A. Paolino, J. L. Kinter, and D. M. Straus, 2001: Impact of tropical subseasonal SST variability on seasonal mean climate simulations. Mon. Wea. Rev., 129 , 853868.

    • Search Google Scholar
    • Export Citation
  • Kousky, V. E., and D. P. Casarin, 1986: Rainfall anomalies in southern Brazil and related atmospheric circulation features. Extended Abstracts, Second Int. Conf. on Southern Hemisphere Meteorology, Wellington, New Zealand, Amer. Meteor. Soc., 435–438.

    • Search Google Scholar
    • Export Citation
  • Lacis, A. A., and J. Hansen, 1974: A parameterization for the absorption of solar radiation in the earth’s atmosphere. J. Atmos. Sci., 31 , 118133.

    • Search Google Scholar
    • Export Citation
  • Leith, C. E., 1974: Theoretical skill of Monte Carlo forecasts. Mon. Wea. Rev., 102 , 409418.

  • Lenters, J. D., and K. H. Cook, 1999: Summertime precipitation variability over South America: Role of the large-scale circulation. Mon. Wea. Rev., 127 , 409431.

    • Search Google Scholar
    • Export Citation
  • Liebmann, B., and C. A. Smith, 1996: Description of a complete (interpolated) outgoing long-wave radiation dataset. Bull. Amer. Meteor. Soc., 77 , 12751277.

    • Search Google Scholar
    • Export Citation
  • Liebmann, B., G. N. Kiladis, J. A. Marengo, T. Ambrizzi, and J. D. Glick, 1999: Submonthly convective variability over South America and the South Atlantic convergence zone. J. Climate, 12 , 18771891.

    • Search Google Scholar
    • Export Citation
  • Mahrt, L., and H-L. Pan, 1984: A two layer model of soil hydrology. Bound.-Layer Meteor., 29 , 120.

  • Marengo, J. A., B. Liebmann, V. E. Kousky, N. P. Filizola, and I. C. Wainer, 2001: Onset and end of the rainy season in the Brazilian Amazon basin. J. Climate, 14 , 833852.

    • Search Google Scholar
    • Export Citation
  • Mellor, G. L., and T. Yamada, 1982: Development of a turbulence closure model for geophysical fluid processes. Rev. Geophys. Space Phys., 20 , 851875.

    • Search Google Scholar
    • Export Citation
  • Menendez, C. G., A. C. Saulo, and Z-X. Li, 2001: Simulation of South American wintertime climate with a nesting system. Climate Dyn., 17 , 219231.

    • Search Google Scholar
    • Export Citation
  • Misra, V., P. A. Dirmeyer, and B. Kirtman, 2002a: A comparative study of two land surface schemes in regional climate integrations over South America. J. Geophys. Res., 107 , LBA 48.148.9.

    • Search Google Scholar
    • Export Citation
  • Misra, V., P. A. Dirmeyer, B. Kirtman, H-M. Juang, and M. Kanamitsu, 2002b: Regional simulation of interannual variability over South America. J. Geophys. Res., 107 , LBA 3.13.16.

    • Search Google Scholar
    • Export Citation
  • Miyakoda, K., and J. Sirutis, 1977: Comparative integrations of global spectral models with various parameterized processes of subgrid scale vertical transports. Beitr. Phys. Atmos., 50 , 445487.

    • Search Google Scholar
    • Export Citation
  • Moorthi, S., and M. J. Suarez, 1992: Relaxed Arakawa–Schubert: A parameterization of moist convection for general circulation models. Mon. Wea. Rev., 120 , 9781002.

    • Search Google Scholar
    • Export Citation
  • Nigam, S., and E. DeWeaver, 1998: Influence of orography on the extratropical response to El Niño events. J. Climate, 11 , 716733.

  • Paegle, N., and K. C. Mo, 1997: Alternating wet and dry conditions over South America during summer. Mon. Wea. Rev., 125 , 279291.

  • Rao, V. B., C. E. Santo, and S. H. Franchito, 2002: A diagnosis of rainfall over South America during the 1997/98 El Niño Event. Part I: Validation of NCEP–NCAR reanalysis rainfall data. J. Climate, 15 , 502521.

    • Search Google Scholar
    • Export Citation
  • Reynolds, R. W., and T. M. Smith, 1994: Improved global sea surface temperature analyses using optimum interpolation. J. Climate, 7 , 929948.

    • Search Google Scholar
    • Export Citation
  • Ropelewski, C. F., J. E. Janowiak, and M. F. Halpert, 1985: The analysis and display of real time surface climate data. Mon. Wea. Rev., 113 , 11011107.

    • Search Google Scholar
    • Export Citation
  • Saulo, C., M. Nicolini, and S. C. Chou, 1999: Model characterization of the South American low level flow during the 1997–98 sprint summer season. Climate Dyn., 16 , 867881.

    • Search Google Scholar
    • Export Citation
  • Schneider, E. K., 2001: Understanding differences between the equatorial Pacific as simulated by two coupled GCM’s. COLA Tech. Rep. 98, 46 pp. [Available from COLA, 4041 Powder Mill Road, Suite 302, Calverton, MD 20705.].

    • Search Google Scholar
    • Export Citation
  • Slingo, J. M., 1987: The development of verification of a cloud prediction scheme for the ECMWF model. Quart. J. Roy. Meteor. Soc., 13 , 899927.

    • Search Google Scholar
    • Export Citation
  • Tanajura, C., 1996: Modeling and analysis of the South American summer climate. Ph.D. dissertation, University of Maryland at College Park, 164 pp.

    • Search Google Scholar
    • Export Citation
  • Tiedtke, M., 1984: The effect of penetrative cumulus convection on the large-scale flow in a general circulation model. Beitr. Phys. Atmos., 57 , 216239.

    • Search Google Scholar
    • Export Citation
  • Wang, M., and J. Paegle, 1996: Impact of analysis uncertainty upon regional atmospheric moisture flux. J. Geophys. Res., 101 , 72917303.

    • Search Google Scholar
    • Export Citation
  • Wilby, R. L., and T. M. L. Wigley, 1997: Downscaling general circulation mode output: A review of methods and limitations. Prog. Phys. Geogr., 21 , 530548.

    • Search Google Scholar
    • Export Citation
  • 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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