Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 9 2 2009 10.5194/acpd-9-8943-2009 http://www.atmos-chem-phys-discuss.net/9/8943/2009/ http://www.atmos-chem-phys-discuss.net/9/8943/2009/acpd-9-8943-2009.html http://www.atmos-chem-phys-discuss.net/9/8943/2009/acpd-9-8943-2009.pdf 8943 8991 2009-04-03 Orographic cirrus in the future climate H. Joos hanna.joos@env.ethz.ch P. Spichtinger U. Lohmann Institute for Atmospheric and Climate Science, ETH Zurich, Universitaetsstrasse 16, 8092 Zurich, Switzerland A cloud resolving model (CRM) is used to investigate the formation of orographic cirrus clouds in the current and future climate. The formation of cirrus clouds depends on a variety of dynamical and thermodynamical processes, which act on different scales. First, the capability of the CRM in realistically simulating orographic cirrus clouds has been tested by comparing the simulated results to aircraft measurements of an orographic cirrus cloud. The influence of a warmer climate on the microphysical and optical properties of cirrus clouds has been investigated by initializing the CRM with vertical profiles of horizontal wind, temperature and moisture from IPCC A1B simulations for the current climate and for the period 2090–2099 for two regions representative for North and South America. In a future climate, the increase in moisture dampens the vertical propagation of gravity waves and the occurring vertical velocities. Together with higher temperatures fewer ice crystals nucleate homogeneously. Assuming that the relative humidity does not change in a warmer climate the specific humidity in the model is increased. This increase in specific humidity in a warmer climate results in a higher ice water content. The net effect of a reduced ice crystal number concentration and a higher ice water content is an increased optical depth. Bögel, W. and Baumann, R.: Test and Calibration of the DLR Falcon Wind Measuring System by Maneuvers, J. Atmos. Ocean. Tech., 8, 5–18, 1991. Chen, T., Rossow, W., and Zhang, Y.: Radiative effects of cloud-type variations, J. Climate, 13, 264–286, 2000. Christensen, J., Hewitson, B., Busuioc, A., Chen, A., Gao, X., Held, I., Jones, R., Kolli, R., Kwon, W.-T., Laprise, R., Magana~Rueda, V., Mearns, L., Menendez, C., Raisanen, J., Rinke, A., Sarr, A., and Whetton, P.: Climate Change 2007: The Physical Science Basis. Contributing of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, chap. Regional Climate Projections, Cambridge University Press,Cambridge, UK and New York, NY, USA, 2007. Clark, T. and Farley, R.: Severe downslope windstorm calculations in two and three spatial dimensions using anelastic interactive grid nesting: A possible mechanism for gustiness, J. Atmos. Sci., 41, 329–350, 1984. Dean, S., Lawrence, B., Grainger, R., and Heuff, D.: Orographic cloud in a GCM: the missing cirrus, Clim. Dynam., 24, 771–780, 2005. Dörnbrack, A.: Turbulent mixing by breaking gravity waves, J. Fluid Mech., 375, 113–141, 1998. Durran, D. and Klemp, J.: A compressible model for the simulation of moist mountain waves, Mon. Weather Rev., 111, 2341–2361, 1983. Ebert, E. and Curry, J.: A parameterization of ice cloud optical properties for climate models, J. Geophys. Res., 97(D4), 3831–3836, 1992. Fu, Q. and Liou, K.: Parameterization of the Radiative Properties of Cirrus Clouds, J. Atmos. Sci., 50, 2008–2025, 1992. Fusina, F., Spichtinger, P., and Lohmann, U.: The impact of ice supersaturated regions and thin cirrus on radiation in the mid latitudes, J. Geophys. Res., 112, D24S14, \doi10.1029/2007JD008449, 2007. Gayet, J.-F., Auriol, F., Minikin, A., Ström, J., Seifert, M., Krejci, R., Petzold, A., Febvre, G., and Schumann, U.: Quantitative measurement of the microphysical and optical properties of cirrus clouds with four different in-situ probes: Evidence of small ice crystals, Geophys. Res. Lett., 29(24), 2230, \doi10.1029/2001GL014342, 2002. Gayet, J.-F., Ovarlez, J., Shcherbakov, V., Ström, J., Schumann, U., Minikin, A., Auriol, F., and Petzold, A.: Cirrus cloud microphysical and optical properties at southern and northern midlatitudes during the INCA experiment, J. Geophys. Res., 109, D20206, \doi10.1029/2004JD004803, 2004. Grabowski, W. and Smolarkiewicz, P.: A multiscale anelastic model for meteorological research, Mon. Weather Rev., 130, 939–956, 2002. Hastings, D., Dunbar, P., Elphingstone, G M., Bootz, M., Murakami, H., Maruyama, H., Masaharu, H., Holland, P., Payne, J., Bryant, N., Logan, T., Muller, J.-P., Schreier, G., and MacDonald, J.: The Global Land One-kilometer Base Elevation (GLOBE) Digital Elevation Model, Version 1.0., online availabel at: http://www.ngdc.noaa.gov/mgg/topo/globe.html, 1999. Held, I. and Soden, B.: Water vapor feedback and global warming, Annu. Rev. Energ. Env., 25, 441–475, 2000. Jiang, Q.: Moist dynamics and orographic precipitation, Tellus, 55A, 301–316, 2003. Joos, H., Spichtinger, P., Lohmann, U., Gayet, J.-F., and Minikin, A.: Orographic cirrus in the global climate model ECHAM5, J. Geophys. Res., 113, D18205, \doi10.1029/2007JD009605, 2008. Kärcher, B. and Lohmann, U.: A parameterization of cirrus cloud formation: Homogeneous freezing of supercooled aerosols, J. Geophys. Res., 107(D2), 4010, doi:10.1029/2001JD000470, 2002. Kärcher, B. and Ström, J.: The roles of dynamical variability and aerosols in cirrus cloud formation, Atmos. Chem. Phys., 3, 823–838, 2003. Koop, T., Luo, B., Tsias, A., and Peter, T.: Water activity as the determinant for homogeneous ice nucleation in aqueous solutions, Nature, 406, 611–614, 2000. Meehl, G., Stocker, T., Collins, W., Friedlingstein, P., Gaye, A., Gregory, J., Kitoh, A., Knutti, R., Murphy, J., Noda, A., Raper, S., Watterson, I., Weaver, A., and Zhao, Z.-C.: Climate Change 2007: The physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, chap. Global Climate Projections, Cambridge University Press,Cambridge, UK and New York, NY, USA, 2007. Noone, K., Ogran, J., Heintzenberg, J., Charlson, R., and Covert, D.: Design and calibration of a counterflow virtual impactor for sampling of atmospheric fog and cloud droplets, Aerosol Sci. Tech., 8, 235–244, 1993. Penner, J. E., Chen, Y., Wang, M., and Liu, X.: Possible influence of anthropogenic aerosols on cirrus clouds and anthropogenic forcing, Atmos. Chem. Phys., 9, 879–896, 2009. Prusa, J., Smolarkiewicz, P., and Wyszogrodzki, A.: EULAG, a computational model for multiscale flows, Comput. Fluids, 37, 1193–1207, 2008. Smolarkiewicz, P. and Margolin, L.: On Forward-in-Time Differencing for Fluids: an Eulerian/Semi-Lagrangian Non-Hydrostatic Model for Stratified Flows, Atmos.-Ocean, 35, 127–152, 1997. Spichtinger, P. and Gierens, K. M.: Modelling of cirrus clouds – Part 1a: Model description and validation, Atmos. Chem. Phys., 9, 685–706, 2009. Spichtinger, P., Gierens, K., and Dörnbrack, A.: Formation of ice supersaturation by mesoscale gravity waves, Atmos. Chem. Phys., 5, 1243–1255, 2005a. Spichtinger, P., Gierens, K., and Wernli, H.: A case study on the formation and evolution of ice supersaturation in the vicinity of a warm conveyor belt's outflow region, Atmos. Chem. Phys., 5, 973–987, 2005b. Zhang, M., Lin, W., Klein, S., Bacmeister, J., Bony, S., Cederwall, R., DelGenio, A., Hack, J., Loeb, N., Lohmann, U., Minnis, P., Musat, I., Pincus, R., Stier, P., Suarez, M., Webb, M., Wu, J., Xie, S., Yao, M., and Zhang, J.: Comparing clouds and their seasonal variations in 10 atmospheric general circulation models with satellite measurements, J. Geophys.Res., 110, D15S02, \doi10.1029/2004JD005021, 2005.