• Aceituno, P., 1988: On the functioning of the Southern Oscillation in the South American sector. Part I: Surface climate. Mon. Wea. Rev., 116 , 505524.

    • Search Google Scholar
    • Export Citation
  • Bengtsson, L., , U. Schlese, , E. Roeckner, , M. Latif, , T. P. Barnett, , and N. E. Graham, 1993: A two-tiered approach to long-range climate forecasting. Science, 261 , 10261029.

    • Search Google Scholar
    • Export Citation
  • Berbery, E. H., , and E. A. Collini, 2000: Springtime precipitation and water vapor flux over southeastern South America. Mon. Wea. Rev., 128 , 13281346.

    • Search Google Scholar
    • Export Citation
  • Bhaskaran, B., , R. G. Jones, , J. M. Murphy, , and M. Noguer, 1996: Simulations of the Indian summer monsoon using a nested regional climate model: Domain size experiments. Climate Dyn., 12 , 573587.

    • 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
  • Dickinson, R. E., , A. Henderson-Sellers, , and P. J. Kennedy, 1993: Biosphere–atmosphere transfer scheme (BATS) version le as coupled to the NCAR community climate model. NCAR Tech. Note NCAR/TN-387 + STR, 72 pp.

    • Search Google Scholar
    • Export Citation
  • Enfield, D. B., 1996: Relationship of inter-American rainfall to tropical Atlantic and Pacific SST variability. Geophys. Res. Lett., 23 , 33053308.

    • Search Google Scholar
    • Export Citation
  • Figueroa, S. N., , P. Satyamurty, , and P. L. da Silva 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
  • Fu, R., , R. E. Dickinson, , M. Chen, , and H. Wang, 2001: How do tropical sea surface temperatures influence the seasonal distribution of precipitation in the equatorial Amazon? J. Climate, 14 , 40034026.

    • Search Google Scholar
    • Export Citation
  • Gedney, N., , and P. J. Valdez, 2000: The effect of Amazonian deforestation on the northern hemisphere circulation and climate. Geophys. Res. Lett., 27 , 30533056.

    • Search Google Scholar
    • Export Citation
  • Giorgi, F., , and M. R. Marinucci, 1996: A study of sensitivity of simulated precipitation to model resolution and its implications for climate studies. Mon. Wea. Rev., 124 , 148166.

    • 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.

  • Giorgi, F., , M. R. Marinucci, , and G. T. Bates, 1993a: Development of a second-generation regional climate model (RegCM2). Part I: Boundary layer and radiative transfer processes. Mon. Wea. Rev., 121 , 27952813.

    • Search Google Scholar
    • Export Citation
  • Giorgi, F., , M. R. Marinucci, , and G. T. Bates, 1993b: Development of a second-generation regional climate model (RegCM2). Part II: Convective processes and assimilation of lateral boundary conditions. Mon. Wea. Rev., 121 , 28142832.

    • Search Google Scholar
    • Export Citation
  • Graham, N., 1994: Experimental forecasts of wet season precipitation in Northeast Brazil using a GCM. Proc. 18th Annual NOAA Climate Diagnostics Workshop, Boulder, CO, NOAA, 378–381.

    • Search Google Scholar
    • Export Citation
  • Grell, G. A., 1993: Prognostic evaluation of assumptions used by cumulus parameterizations. Mon. Wea. Rev., 121 , 764787.

  • Grimm, A. M., , S. T. Ferraz, , and J. Gomes, 1998: Precipitation anomalies in southern Brasil associated with El Niño and La Niña events. J. Climate, 11 , 28632880.

    • Search Google Scholar
    • Export Citation
  • Hastenrath, S., 1990: Prediction of northeast Brazil rainfall anomalies. J. Climate, 3 , 893904.

  • Hastenrath, S., , and L. Heller, 1977: Dynamics of climatic hazards in Northeast Brazil. Quart. J. Roy. Meteor. Soc., 103 , 411425.

  • Horel, J. D., , J. B. Pechmann, , A. N. Hahmann, , and J. E. Geisler, 1994: Simulations of the Amazon Basin circulation with a regional model. J. Climate, 7 , 5671.

    • Search Google Scholar
    • Export Citation
  • Hsie, E. Y., , R. A. Anthes, , and D. Keyser, 1984: Numerical simulation of frontogenesis in a moist atmosphere. J. Atmos. Sci., 41 , 25812594.

    • Search Google Scholar
    • Export Citation
  • Jones, R. G., , J. M. Murphy, , and M. Noguer, 1995: Simulation of climate change over Europe using a nested regional climate model. I: Assessment of control climate, including sensitivity to location of lateral boundaries. Quart. J. Roy. Meteor. Soc., 121 , 14131449.

    • Search Google Scholar
    • Export Citation
  • Kalnay, E., and Coauthors. 1996: The NCEP/NCAR 40-Year Reanalysis Project. Bull. Amer. Meteor. Soc., 77 , 437471.

  • Liebmann, B., , and J. Marengo, 2001: Interannual variability of the rainy season and rainfall in the Brazilian Amazon basin. J. Climate, 14 , 43084318.

    • Search Google Scholar
    • Export Citation
  • Mason, S. J., , L. Goddard, , N. E. Graham, , E. Yulaeva, , L. Sun, , and P. A. Arkin, 1999: The IRI Seasonal Climate Prediction System and the 1997/98 El Niño event. Bull. Amer. Meteor. Soc., 80 , 18531873.

    • Search Google Scholar
    • Export Citation
  • Moura, A. D., , and J. Shukla, 1981: On the dynamics of droughts in Northeast Brazil: Observations, theory and numerical experiments with a general circulation model. J. Atmos. Sci., 38 , 26532675.

    • Search Google Scholar
    • Export Citation
  • New, M. G., , M. Hulme, , and P. D. Jones, 2000: Representing twentieth-century space–time climate variability. Part II: Development of 1901–96 monthly grids of terrestrial surface climate. J. Climate, 13 , 22172238.

    • Search Google Scholar
    • Export Citation
  • Reynolds, R. W., 1988: A real-time global sea surface temperature analysis. J. Climate, 1 , 7586.

  • Rojas, M., , and A. Seth, 2003: Simulation and sensitivity in a nested modeling system for South America. Part II: GCM boundary forcing. J. Climate, 16 , 24542471.

    • Search Google Scholar
    • Export Citation
  • Ropelewski, C. F., , and M. S. Halpert, 1987: Global and regional scale precipitation patterns associated with the El Niño/Southern Oscillation. Mon. Wea. Rev., 115 , 16061626.

    • Search Google Scholar
    • Export Citation
  • Seth, A., , and F. Giorgi, 1998: The effects of domain choice on summer precipitation simulation and sensitivity in a regional climate model. J. Climate, 11 , 26982712.

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

  • Uvo, C. B., , C. A. Repelli, , S. E. Zebiak, , and Y. Kushnir, 1998: The relationships between tropical Pacific and Atlantic SST and northeast Brazil monthly precipitation. J. Climate, 11 , 551562.

    • Search Google Scholar
    • Export Citation
  • Walker, G. T., 1928: Ceará (Brazil) famines and general air movement. Beitr. Phys. Freien Atmos., 14 , 8893.

  • Wallace, J. M., , E. M. Rasmusson, , and H. von Storch, 1998: On the structure and evolution of ENSO-related climate variability in the tropical Pacific: Lessons from TOGA. J. Geophys. Res., 103 , 1424114259.

    • Search Google Scholar
    • Export Citation
  • Ward, M. N., , C. K. Folland, , K. Maskell, , A. W. Colman, , D. P. Rowell, , and K. B. Lane, 1991: Experimental seasonal forecasting of tropical rainfall at the UK Meteorological Office. Prediction of Interannual Climate Variability, J. Shukla, Ed., Springer-Verlag, 197–216.

    • Search Google Scholar
    • Export Citation
  • Xie, P., , and P. A. 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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Simulation and Sensitivity in a Nested Modeling System for South America. Part I: Reanalyses Boundary Forcing

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  • 1 International Research Institute for Climate Prediction, Columbia University, Palisades, New York
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Abstract

A regional climate model driven by reanalyzed atmospheric forcing is used to investigate 1) the large-scale circulation anomalies that were driven by sea surface temperatures (SSTs), which resulted in extreme rainfall anomalies during January–May 1983 (dry) and 1985 (wet) in tropical South America; 2) the effects of vegetation and soil moisture in the interior Amazon basin on regional circulations, moisture transport, and rainfall; and 3) the sensitivity of regional model results to domain size. Seasonal integrations demonstrated that by prescribing observed SSTs and applying reanalyses-derived forcing along the boundaries of the control domain, the regional climate model (RegCM) was able to simulate the dramatically different large-scale circulations in the two years, as well as the resulting rainfall differences. Thus, the large-scale forcing apparently has a first-order effect on the region. The regional model shows reduced rainfall in the western Amazon compared with observed estimates that are associated with weak low-level moisture transport from the Atlantic. The sensitivity experiments to surface forcing in the Amazon, employing a large (10.8 × 107 km2) and a small (5.7 × 107 km2) domain, show that both simulation and sensitivity are a function of domain size in the Tropics. However, the spatial scales and hence the domains required are larger in the Tropics than in the midlatitudes. The perturbations employed in this study influence the large-scale tropical circulation. This feedback is damped by the lateral boundary conditions of the control (smaller) domain.

Corresponding author address: Dr. Anji Seth, International Research Institute for Climate Prediction, Lamont-Doherty Earth Observatory, Columbia University, 61 Route 9W, Palisades, NY 10964. Email: seth@iri.columbia.edu

Abstract

A regional climate model driven by reanalyzed atmospheric forcing is used to investigate 1) the large-scale circulation anomalies that were driven by sea surface temperatures (SSTs), which resulted in extreme rainfall anomalies during January–May 1983 (dry) and 1985 (wet) in tropical South America; 2) the effects of vegetation and soil moisture in the interior Amazon basin on regional circulations, moisture transport, and rainfall; and 3) the sensitivity of regional model results to domain size. Seasonal integrations demonstrated that by prescribing observed SSTs and applying reanalyses-derived forcing along the boundaries of the control domain, the regional climate model (RegCM) was able to simulate the dramatically different large-scale circulations in the two years, as well as the resulting rainfall differences. Thus, the large-scale forcing apparently has a first-order effect on the region. The regional model shows reduced rainfall in the western Amazon compared with observed estimates that are associated with weak low-level moisture transport from the Atlantic. The sensitivity experiments to surface forcing in the Amazon, employing a large (10.8 × 107 km2) and a small (5.7 × 107 km2) domain, show that both simulation and sensitivity are a function of domain size in the Tropics. However, the spatial scales and hence the domains required are larger in the Tropics than in the midlatitudes. The perturbations employed in this study influence the large-scale tropical circulation. This feedback is damped by the lateral boundary conditions of the control (smaller) domain.

Corresponding author address: Dr. Anji Seth, International Research Institute for Climate Prediction, Lamont-Doherty Earth Observatory, Columbia University, 61 Route 9W, Palisades, NY 10964. Email: seth@iri.columbia.edu

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