• Allen, M., and M. Davey, 1993: Empirical parameterization of tropical ocean–atmosphere coupling: The “inverse Gill problem.” J. Climate,6, 509–530.

  • Arakawa, A., and W. H. Schubert, 1974: Interaction of a cumulus cloud ensemble with the large-scale environment, Part I. J. Atmos. Sci.,31, 674–701.

  • Betts, A. K., 1982: Saturation point analysis of moist convective overturning. J. Atmos. Sci.,39, 1484–1505.

  • ——, 1986: A new convective adjustment scheme. Part I: Observational and theoretical basis. Quart. J. Roy. Meteor. Soc.,112, 677–691.

  • ——, 1990: Greenhouse warming and the tropical water budget. Bull. Amer. Meteor. Soc.,71, 1464–1465.

  • ——, and W. Ridgway, 1988: Coupling of the radiative, convective, and surface fluxes over the equatorial Pacific. J. Atmos. Sci.,45, 522–536.

  • ——, and ——, 1989: Climatic equilibrium of the atmospheric convective boundary layer over a tropical ocean. J. Atmos. Sci.,46, 2621–2641.

  • Bretherton, C. S., and P. K. Smolarkiewicz, 1989: Gravity waves, compensating subsidence and detrainment around cumulus clouds. J. Atmos. Sci.,46, 740–759.

  • Cacuci, D. G., and M. C. G. Hall, 1984: Efficient estimation of feedback effects with application to climate models. J. Atmos. Sci.,41, 2063–2068.

  • Cess, R. D., and Coauthors, 1995: Absorption of solar radiation by clouds—Observations versus models. Science,267, 496–499.

  • Davey, M. K., and A. Gill, 1987: Experiments on tropical circulation with a simple moist model. Quart. J. Roy. Meteor. Soc.,113, 1237–1269.

  • Gill, A. E., 1980: Some simple solutions for heat-induced tropical circulation. Quart. J. Roy. Meteor. Soc.,106, 447–462.

  • Hall, M. C. G., D. G. Cacuci, and M. E. Schlesinger, 1982: Sensitivity analysis of a radiative-convective model by the adjoint method. J. Atmos. Sci.,39, 2038–2050.

  • Hartmann, D. L., and M. L. Michelsen, 1993: Large-scale effects on the regulation of tropical sea surface temperature. J. Climate,6, 2049–2062.

  • ——, H. H. Hendon, and R. A. Houze Jr., 1984: Some implications of the mesoscale circulations in tropical cloud clusters for large-scale dynamics and climate. J. Atmos. Sci.,41, 113–121.

  • Held, I. M., and M. J. Saurez, 1978: A two-level primitive equation atmospheric model designed for climatic sensitivity experiments. J. Atmos. Sci.,35, 206–229.

  • Houze, R. A., Jr., and A. K. Betts, 1981: Convection in GATE. Rev. Geophys.,19, 541–576.

  • Inamdar, A. K., and V. Ramanathan, 1994: Physics of greenhouse effect and convection in warm oceans. J. Climate,7, 715–731.

  • Inoue, T., 1990: The relationship of sea surface temperature and water vapor amount to convection over the western tropical Pacific revealed from split window measurements. J. Meteor. Soc. Japan,68, 589–606.

  • Kiehl, J. T., and B. P. Briegleb, 1992: Comparison of the observed and calculated clear sky greenhouse effect: Implications for climate studies. J. Geophys. Res.,97, 10 037–10 049.

  • Lahiff, L. N., 1975: A low-latitude atmosphere–ocean climate model. J. Atmos. Sci.,32, 657–674.

  • Lindzen, R. S., 1990: Some coolness concerning global warming. Bull. Amer. Meteor. Soc.,71, 288–299.

  • ——, and S. Nigam, 1987: On the role of sea surface temperature gradients in forcing low-level winds and convergence in the Tropics. J. Atmos. Sci.,44, 2418–2435.

  • Liu, W. T., K. B. Katsaros, and J. A. Businger, 1979: Bulk parameterization of air–sea exchanges of heat and water vapor including the molecular constraints at the interface. J. Atmos. Sci.,36, 1722–1735.

  • Lorenz, E. N., 1984: Formulation of a low-order model of a moist general circulation. J. Atmos. Sci.,41, 1933–1945.

  • Manabe, S., and R. T. Wetherald, 1967: Thermal equilibrium of the atmosphere with a given distribution of relative humidity. J. Atmos. Sci.,24, 241–259.

  • Miller, R. L., 1996: Tropical thermostats and low cloud cover. J. Climate,9, 409–440.

  • Neelin, J. D., and I. M. Held, 1987: Modeling tropical convergence based on the moist static energy budget. Mon. Wea. Rev.,115, 3–12.

  • Pierrehumbert, R. T., 1995: Thermostats, radiator fins, and the local runaway greenhouse. J. Atmos. Sci.,52, 1784–1806.

  • ——, and H. Yang, 1993: Global chaotic mixing on isentropic surfaces. J. Atmos. Sci.,50, 2462–2480.

  • Prabhakara, C., D. A. Short, and B. E. Vollmer, 1985: El Niño and atmospheric water vapor: Observations from Nimbus 7 SMMR. J. Climate Appl. Meteor.,24, 1311–1324.

  • Ramanathan, V., and W. Collins, 1991: Thermodynamic regulation of ocean warming by cirrus clouds deduced from observations of the 1987 El Niño. Nature,351, 27–32.

  • ——, B. Subasilar, G. J. Zhang, W. Conant, R. D. Cess, J. T. Kiehl, H. Grassl, and L. Shi, 1995: Warm pool heat budget and shortwave cloud forcing—A missing physics? Science,267, 499–503.

  • Randall, D. A., Harshvardhan, D. A. Dazlich, and T. G. Corsetti, 1989: Interactions among radiation, convection, and large-scale dynamics in a general circulation model. J. Atmos. Sci.,46, 1943–1970.

  • Raval, A., and V. Ramanathan, 1989: Observational determination of the greenhouse effect. Nature,342, 758–761.

  • ——, A. H. Oort, and V. Ramaswamy, 1994: Observed dependence of outgoing longwave radiation on sea surface temperature and moisture. J. Climate,7, 807–821.

  • Raymond, D. J., 1994: Convective processes and tropical atmospheric circulations. Quart. J. Roy. Meteor. Soc.,120, 1431–1455.

  • Rennó, N. O., K. A. Emanuel, and P. H. Stone, 1994: Radiative-convective model with an explicit hydrologic cycle 1. Formulation and sensitivity to model parameters. J. Geophys. Res.,99, 14 429–14 441.

  • Rind, D., E.-W. Chiou, W. Chu, J. Larsen, S. Oltmans, J. Lerner, M. P. McCormick, and L. McMaster, 1991: Positive water vapour feedback in climate models confirmed by satellite data. Nature,349, 500–503.

  • Seager, R., 1991: A simple model of the climatology and variability of the low-level wind field in the Tropics. J. Climate,4, 164–179.

  • Sherwood, S. C., 1995: The maintenance of the tropical water vapor distribution. Ph.D. thesis, Scripps Institution of Oceanography, 181 pp. [Available from Scripps Institution of Oceanography, La Jolla, CA 92037.].

  • ——, 1996a: Maintenance of the free-tropospheric tropical water vapor distribution. Part I: Clear regime budget. J. Climate,9, 2903–2918.

  • ——, 1996b: Maintenance of the free-tropospheric tropical water vapor distribution. Part II: Simulation by large-scale advection. J. Climate,9, 2919–2934.

  • ——, V. Ramanathan, T. P. Barnett, M. K. Tyree, and E. Roeckner, 1994: Response of an atmospheric general circulation model to radiative forcing of tropical clouds. J. Geophys. Res.,99, 20 829–20 845.

  • Sinha, A., and M. R. Allen, 1994: Climate sensitivity and tropical moisture distribution. J. Geophys. Res.,99D, 3707–3716.

  • Slingo, A., and J. M. Slingo, 1988: The response of a general circulation model to cloud longwave radiative forcing. I. Introduction and initial experiments. Quart. J. Roy. Meteor. Soc.,114, 1027–1062.

  • Soden, B. J., and R. Fu, 1995: A satellite analysis of deep convection, upper tropospheric humidity, and the greenhouse effect. J. Climate,8, 2333–2351.

  • ——, and J. R. Lanzante, 1996: An assessment of satellite and radiosonde climatologies of upper-tropospheric water vapor. J. Climate,9, 1235–1250.

  • Stephens, G. L., 1990: On the relationship between water vapor over the oceans and sea surface temperature. J. Climate,3, 634–645.

  • Sun, D. Z., and R. S. Lindzen, 1993: Distribution of tropical tropospheric water vapor. J. Atmos. Sci.,50, 1643–1660.

  • ——, and A. H. Oort, 1995: Humidity–temperature relationships in the tropical troposphere. J. Climate,8, 1974–1987.

  • ——, and I. M. Held, 1996: A comparison of modeled and observed relationships between interannual variations of water vapor and temperature. J. Climate,9, 665–675.

  • Thompson, R. M., S. W. Payne, E. E. Recker, and R. J. Reed, 1979:Structure and properties of synoptic-scale wave disturbances in the intertropical convergence zone of the eastern Atlantic. J. Atmos. Sci.,36, 53–72.

  • Wallace, J. M., 1992: Effect of deep convection on the regulation of tropical sea surface temperature. Nature,357, 230–231.

  • Wang, B., and T. Li, 1993: A simple tropical atmosphere model of relevance to short-term climate variations. J. Atmos. Sci.,50, 260–284.

  • Weare, B. C., 1986: A simple model of the tropical atmosphere with circulation dependent heating and specific humidity. J. Atmos. Sci.,43, 2001–2016.

  • Wetherald, R. T., and S. Manabe, 1975: The effect of changing the solar constant on the climate of a general circulation model. J. Atmos. Sci.,32, 2044–2059.

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  • 1 Scripps Institution of Oceanography, La Jolla, California
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Abstract

A simple four-cell model of the tropical atmosphere in equilibrium with its boundaries is introduced, which can support a variable diabatic circulation and prognostic temperature and humidity profiles. The model is used to predict atmospheric perturbations away from the observed base state. Prognostic variables include radiation, surface fluxes, and dynamic transports, with temperature and water vapor levels determined by conservation constraints. The model includes a specially developed water vapor scheme that performs favorably compared with observations. The model is used to simulate the local and nonlocal sensitivity of the tropical maritime atmosphere to changes in surface temperature and other boundary conditions at very large horizontal scales. The main findings are as follows. (i) The sensitivity of boundary layer convergence to sea surface temperature (SST) variations depends on the behavior of convective heating over cooler regions and may be overestimated by heuristic models that ignore or oversimplify thermodynamic and radiative constraints. (ii) The maintenance of humidity equilibrium over weakly convective areas is modulated by local radiative feedback. (iii) Evaporation feedbacks on SST may be overestimated by heuristic arguments that do not carefully treat atmospheric water transport. An explanation for the constant–relative humidity behavior of general circulation models under climate changes is also offered based on the results.

* Current affiliation: Universities Space Research Association, NASA/Goddard Space Flight Center, Greenbelt, Maryland.

Corresponding author address: Dr. Steven Sherwood, Universities Space Research Association, NASA/Goddard Space Flight Center, Mailcode 916, Greenbelt, MD 20771.

Email: ssherwood@alum.mit.edu

Abstract

A simple four-cell model of the tropical atmosphere in equilibrium with its boundaries is introduced, which can support a variable diabatic circulation and prognostic temperature and humidity profiles. The model is used to predict atmospheric perturbations away from the observed base state. Prognostic variables include radiation, surface fluxes, and dynamic transports, with temperature and water vapor levels determined by conservation constraints. The model includes a specially developed water vapor scheme that performs favorably compared with observations. The model is used to simulate the local and nonlocal sensitivity of the tropical maritime atmosphere to changes in surface temperature and other boundary conditions at very large horizontal scales. The main findings are as follows. (i) The sensitivity of boundary layer convergence to sea surface temperature (SST) variations depends on the behavior of convective heating over cooler regions and may be overestimated by heuristic models that ignore or oversimplify thermodynamic and radiative constraints. (ii) The maintenance of humidity equilibrium over weakly convective areas is modulated by local radiative feedback. (iii) Evaporation feedbacks on SST may be overestimated by heuristic arguments that do not carefully treat atmospheric water transport. An explanation for the constant–relative humidity behavior of general circulation models under climate changes is also offered based on the results.

* Current affiliation: Universities Space Research Association, NASA/Goddard Space Flight Center, Greenbelt, Maryland.

Corresponding author address: Dr. Steven Sherwood, Universities Space Research Association, NASA/Goddard Space Flight Center, Mailcode 916, Greenbelt, MD 20771.

Email: ssherwood@alum.mit.edu

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