GCM-Simulated Surface Energy Fluxes in Climate Change Experiments

Martin Wild Department of Geography, Swiss Federal Institute of Technology, Zurich, Switzerland

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Atsumu Ohmura Department of Geography, Swiss Federal Institute of Technology, Zurich, Switzerland

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Ulrich Cubasch Deutsches Klima Rechenzentrum GmbH, Hamburg, Germany

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Abstract

The changes in the surface energy fluxes calculated with a general circulation model under increased levels of carbon dioxide concentration are analyzed and related to the simulation of these fluxes under present-day conditions. It is shown that the errors in the simulated fluxes under present climate are often of similar or larger magnitude than the simulated changes of these quantities. A similar relationship may be found in climate change experiments of many GCMs. Although this does not imply that the projected changes of the fluxes are wrong, more accurate absolute values would improve confidence in GCM-simulated climate change scenarios.

The global mean increase in the downward component of the longwave radiation, which is the direct greenhouse forcing at the surface, is on the order of 10 W m−2 at the time of doubled carbon dioxide in a transient coupled atmosphere–ocean scenario experiment. This is an amount similar to the underestimation of this quantity in the present-day simulations compared to surface observations. Thus, it is only with doubled carbon dioxide concentration that the simulated greenhouse forcing at the surface reaches the values observed at present.

The simulated shortwave radiation budget at the surface is less affected by the increased levels of carbon dioxide than the longwave budget on the global scale. Regionally and seasonally, the changes in the incoming shortwave radiation at the surface can exceed 20 W m−2, mainly due to changes in cloud amounts. The projected changes, however, are generally of smaller magnitude than the systematic errors in the control run at the majority of 720 observation sites.

The positive feedback between excessive radiation and surface processes leading to excessive summer dryness and temperatures over continental surfaces in the control run is enhanced in the doubled carbon dioxide experiment, resulting in a massive increase in the projected surface temperature.

In the high-resolution T106 time-slice scenario experiment performed in this study the global mean latent heat flux and associated intensity of the hydrological cycle is slightly decreased rather than increased with doubled carbon dioxide. A reduction in surface wind speed in the T106 scenario is suggested as a major factor for the reverse of sign.

The improved representation of the orography with T106 resolution allows a better estimate of the projected changes of surface energy fluxes in mountain areas, as demonstrated for the European Alps.

Corresponding author address: Dr. Martin Wild, Geography Department, Swiss Federal Institute of Technology, Winterhurerstrasse 190, CH-8057 Zurich, Switzerland.

Email: wild@geo.umnw.ethz.ch

Abstract

The changes in the surface energy fluxes calculated with a general circulation model under increased levels of carbon dioxide concentration are analyzed and related to the simulation of these fluxes under present-day conditions. It is shown that the errors in the simulated fluxes under present climate are often of similar or larger magnitude than the simulated changes of these quantities. A similar relationship may be found in climate change experiments of many GCMs. Although this does not imply that the projected changes of the fluxes are wrong, more accurate absolute values would improve confidence in GCM-simulated climate change scenarios.

The global mean increase in the downward component of the longwave radiation, which is the direct greenhouse forcing at the surface, is on the order of 10 W m−2 at the time of doubled carbon dioxide in a transient coupled atmosphere–ocean scenario experiment. This is an amount similar to the underestimation of this quantity in the present-day simulations compared to surface observations. Thus, it is only with doubled carbon dioxide concentration that the simulated greenhouse forcing at the surface reaches the values observed at present.

The simulated shortwave radiation budget at the surface is less affected by the increased levels of carbon dioxide than the longwave budget on the global scale. Regionally and seasonally, the changes in the incoming shortwave radiation at the surface can exceed 20 W m−2, mainly due to changes in cloud amounts. The projected changes, however, are generally of smaller magnitude than the systematic errors in the control run at the majority of 720 observation sites.

The positive feedback between excessive radiation and surface processes leading to excessive summer dryness and temperatures over continental surfaces in the control run is enhanced in the doubled carbon dioxide experiment, resulting in a massive increase in the projected surface temperature.

In the high-resolution T106 time-slice scenario experiment performed in this study the global mean latent heat flux and associated intensity of the hydrological cycle is slightly decreased rather than increased with doubled carbon dioxide. A reduction in surface wind speed in the T106 scenario is suggested as a major factor for the reverse of sign.

The improved representation of the orography with T106 resolution allows a better estimate of the projected changes of surface energy fluxes in mountain areas, as demonstrated for the European Alps.

Corresponding author address: Dr. Martin Wild, Geography Department, Swiss Federal Institute of Technology, Winterhurerstrasse 190, CH-8057 Zurich, Switzerland.

Email: wild@geo.umnw.ethz.ch

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  • Barry, R. G., 1992: Mountain Weather and Climate. 2d ed. Routledge, 402 pp.

  • Bengtsson, L., M. Botzet, and M. Esch, 1995: Hurricane-type vortices in a general circulation model: Part 1. Tellus,47A, 175–196.

  • ——, ——, and ——, 1996: Will greehouse gas-induced warming over the next 50 years lead to higher frequency and greater intensity of hurricanes? Tellus,48A, 57–73.

  • Budyko, M. I., 1974: Climate and Life. Academic Press, 508 pp.

  • Cubasch, U., K. Hasselmann, H. Hoeck, E. Maier-Reimer, U. Mikolajewicz, B. D. Santer, and R. Sausen, 1992: Time-dependent greenhouse warming computations with a coupled ocean–atmosphere model. Climate Dyn.,8, 55–69.

  • ——, B. Santer, A. Hellbach, G. Hegerl, H. Höck, E. Maier-Reimer, U. Mikolajewicz, A. Stössel, and R. Voss, 1994: Monte Carlo climate change forecasts with a global coupled ocean–atmosphere model. Climate Dyn.,10, 1–19.

  • ——, J. Waszkewitz, G. C. Hegerl, and J. Perlwitz, 1995a: Regional climate changes as simulated in time-slice experiments. Climate Change,31, 273–304.

  • ——, G. C. Hegerl, A. Hellbach, H. Höck, U. Mikolajewicz, B. D. Santer, and R. Voss, 1995b: A climate change simulation starting 1935. Climate Dyn.,11, 71–84.

  • Dümenil, L., and E. Todini, 1992: A rainfall runoff scheme for use in the Hamburg climate model. Advances in Numerical Hydrology. A Tribute of James Dooge, J. P. O’Kane, Ed., European Geophysical Society Series on Hydrological Sciences, Vol. 1, Elsevier Science, 129–157.

  • Garratt, J. R., 1994: Incoming shortwave fluxes at the surface—A comparison of GCM results with observations. J. Climate,7, 72–80.

  • ——, and A. J. Prata, 1996: Downwelling longwave fluxes at continental surfaces—A comparison with GCM simulations and implications for the global land-surface radiation budget. J. Climate,9, 646–655.

  • Gates, W. L., 1992: AMIP: The Atmospheric Model Intercomparison Project. Bull. Amer. Meteor. Soc.,73, 1962–1970.

  • Giorgetta, M., and M. Wild, 1995: The water vapor continuum and its representation in ECHAM4. Max-Planck Institute for Meteorology Rep. 162, 38 pp. [Available from MPI für Meteorologie, Bundesstr. 55, D-20146 Hamburg, Germany.].

  • Gutowski, W. J., D. S. Gutzler, and W. C. Wang, 1991: Surface energy balances of three general circulation models: Implications for simulating regional climate change. J. Climate,4, 121–134.

  • Hasselmann, K., R. Sausen, E. Maier-Reimer, and R. Voss, 1993: On the cold start problem with coupled atmosphere–ocean models. Climate Dyn.,9, 53–61.

  • Hense, A., M. Kerschgens, and E. Raschke, 1982: An economical method for computing radiative transfer in circulation models. Quart. J. Roy. Meteor. Soc.,108, 231–252.

  • IPCC, 1990: Climate Change, The IPCC Scientific Assessment. J. Houghton, G. J. Jenkins, and J. J. Ephraums, Eds., Cambridge University Press, 364 pp.

  • ——, 1996: Climate Change 1995, Impacts of Climate Change, Adaption and Mitigation, R. T. Watson, M. Zinyowera, and R. M. Mcss, Eds., Cambridge University Press, 878 pp.

  • Kerschgens, M. U., E. Pilz, and E. Raschke, 1978: A modified two stream approximation for computations of the solar radiation budget in a cloudy atmosphere. Tellus,30, 429–435.

  • Louis, J. F., 1979: A parametric model of vertical eddy fluxes in the atmosphere. Bound.-Layer Meteor.,17, 187–202.

  • Mahfouf, J. F., D. Cariolle, J.-F. Royer, J.-F. Geleyn, and B. Timbal, 1994: Response of the Météo-France climate model to changes in CO2 and sea surface temperature. Climate Dyn.,9, 345–362.

  • Maier-Reimer, E., U. Mikolajewicz, and K. Hasselmann, 1993: Mean circulation of the Hamburg LSG OGCM and its sensitivity to the thermohaline surface forcing. J. Phys. Oceanogr.,23, 731–757.

  • Morcrette, J. J., 1991: Radiation and cloud radiative properties in the European Centre for Medium Range Weather Forecasts forecasting system. J. Geophys. Res.,96, 9121–9132.

  • Ohmura, A., and H. Gilgen, 1993: Re-evaluation of the global energy balance. Interactions between Global Climate Subsystems, the Legacy of Hann, Geophys. Monogr., No. 75, International Union of Geodesy and Geophysics and Amer. Geophys. Union, 93–110.

  • ——, ——, and M. Wild, 1989: Global Energy Balance Archive GEBA, World Climate Program–Water Project A7, Report 1: Introduction. Zuercher Geografische Schriften 34, Verlag der Fachvereine, 62 pp. [Available from Prof. A. Ohmura, ETH Zürich, CH-8057 Zürich, Switzerland.].

  • ——, M. Wild, and L. Bengtsson, 1996: A possible change in mass balance of greenland and antarctic ice sheets in the coming century. J. Climate,9, 2124–2135.

  • Oki, T., A. Mushiake, K. Masuda, and H. Matsuyama, 1993: Global runoff estimation by atmospheric water balance using ECMWF data-set. IAHS Publ. 214, 163–167.[Available from IAHS Press, Institute of Hydrology, Wallingford, Oxfordshire OX10 8BB, United Kingdom.].

  • Randall, D. A., and Coauthors 1992: Intercomparison and interpretation of surface energy fluxes in atmospheric general circulation models. J. Geophys. Res.,97, 3711–3725.

  • Roeckner, E., M. Rieland, and E. Keup, 1991: Modelling of cloud and radiation in the ECHAM model. ECMWF/WCRP Workshop on clouds, radiative transfer and the hydrological cycle. Reading, United Kingdom, ECMWF, 199–222.

  • ——, and Coauthors, 1992: Simulation of the present-day climate with the ECHAM model: Impact of model physics and resolution. Max-Planck Institute for Meteorology Rep. 93, 171 pp. [Available from MPI für Meteorologie, Bundesstr. 55, D-20146 Hamburg, Germany.].

  • Timbal, B., J.-F. Mahfouf, J.-F. Royer, and D. Cariolle, 1995: Sensitivity to prescribed changes in sea surface temperature and sea ice in doubled carbon dioxide experiments. Climate Dyn.,12, 1–20.

  • Watterson, I. G., and M. R. Dix, 1996: Influence on surface energy fluxes in simulated present and doubled CO2 climates, Climate Dyn.,12, 359–370.

  • WCRP, 1991: Radiation and climate. Second Workshop of the Baseline Surface Radiation Network, Geneva, Switzeland, WCRP- 64, 26 pp.

  • Wild, M., A. Ohmura, H. Gilgen, and E. Roeckner, 1995a: Validation of GCM simulated radiative fluxes using surface observations. J. Climate,8, 1309–1324.

  • ——, ——, ——, and ——, 1995b: Regional climate simulation with a high resolution GCM: Surface radiative fluxes. Climate Dyn.,11, 469–486.

  • ——, L. Dümenil, and J. P. Schulz, 1996a: Regional climate simulation with a high resolution GCM: Surface hydrology. Climate Dyn.,12, 755–774.

  • ——, A. Ohmura, H. Gilgen, E. Roeckner, and M. Giorgetta, 1996b:Improved representation of surface and atmospheric radiation budgets in ECHAM4. Max Planck Institute for Meteorology Rep. 200, 32 pp. [Available at MPI für Meteorologie, Bundesstr. 55, D-20146 Hamburg, Germany.].

  • Zdunkowski, W. G., R. M. Welch, and G. Korb, 1980: An investigation of the structure of typical two stream methods for the calculation of solar fluxes and heating rates in clouds. Beitr. Phys. Atmos.53, 147–166.

  • Zhang, G. J., and M. J. McPhaden, 1995: The relationship between sea surface temperature and latent heat flux in the equatorial Pacific. J. Climate,8, 589–605.

  • Zhang, M. H., 1996: Impact of the convection-wind-evaporation feedback on surface climate simulations in general circulation models. Climate Dyn.,12, 299–312.

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