Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 10 1 2010 10.5194/acpd-10-1595-2010 http://www.atmos-chem-phys-discuss.net/10/1595/2010/ http://www.atmos-chem-phys-discuss.net/10/1595/2010/acpd-10-1595-2010.html http://www.atmos-chem-phys-discuss.net/10/1595/2010/acpd-10-1595-2010.pdf 1595 1629 2010-01-20 Cluster analysis of midlatitude oceanic cloud regimes – Part 2: Temperature sensitivity of cloud properties N. D. Gordon n.gordon@leeds.ac.uk J. R. Norris Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, USA now at: School of Earth and Environment, University of Leeds, Leeds, UK Clouds have a large impact on Earth's radiation budget by reflecting incoming solar radiation and trapping longwave radiation emitted from the surface. The present balance could change as the atmosphere warms from increasing anthropogenic greenhouse gases, thus altering the net radiation flux and mitigating or exacerbating the initial temperature increase. To ascertain the sign and magnitude of cloud-climate feedback, we must better understand the way in which clouds interact with their environment and how temperature modifies cloud and radiative properties. Since global climate models do not consistently and correctly simulate clouds, we undertake an observational analysis of how midlatitude oceanic clouds change with temperature when dynamical processes are held constant (i.e., partial derivative with respect to temperature). For each of the seven cloud regimes identified through <i>k</i>-means clustering of daily satellite data in the companion study, we examine the difference in cloud and radiative properties between warm and cold subsets. To avoid misinterpreting a cloud response to large-scale dynamical forcing as a cloud response to temperature, we require horizontal and vertical temperature advection in the warm and cold subsets to have near-median values in three layers of the troposphere. Across all of the seven clusters, we find that cloud fraction is smaller and cloud optical thickness is mostly larger for the warm subset. Cloud top pressure is higher for the three low-level cloud regimes and lower for the cirrus regime. The net upwelling radiation flux at the top of the atmosphere is larger for the warm subset in every cluster except cirrus, and larger when averaged over all clusters. This implies that the direct response of midlatitude oceanic clouds to increasing temperature acts as a negative feedback on the climate system. Note that the cloud response to atmospheric dynamical changes produced by global warming, which we do not consider in this study, may differ, and the total cloud feedback may be positive. Betts,~A K. and Harshvardhan: Thermodynamic constraint on the cloud liquid water feedback in climate models, J. Geophys. Res., 92, 8483–8485, 1987. Bony,~S., Lau,~K.-M., and Sud,~Y C.: Sea surface temperature and large-scale circulation influences on tropical greenhouse effect and cloud radiative forcing, J. Climate, 10, 2055–2077, 1997. Bony,~S., Dufresne,~J.-L., Le Treut,~H., Morcrette,~J.-J., and Senior,~C.: On dynamic and thermodynamic components of cloud changes, Clim. Dynam., 22, 71–86, 2004. Cess,~R D. and Udelhofen,~P M.: Climate change during 1985–1999: cloud interactions determined from satellite measurements, Geophys. Res. Lett., 30, 1019, \doi10.1029/2002GL016128, 2003. Cess,~R D., Harrison,~E F., Minnis,~P., Barkstrom,~B R., Ramanathan,~V., and Kwon,~T Y.: Interpretation of seasonal cloud-climate interactions using Earth Radiation Budget Experiment data, J. Geophys. Res., 97, 7613–7617, 1992. Chang,~F.-L. and Coakley,~J A.: Relationships between marine stratus cloud optical depth and temperature: inferences from AVHRR observations, J. Climate, 20, 2022–2036, 2007. Clement,~A C., Burgman,~R., and Norris,~J R.: Observational and model evidence for positive low-level cloud feedback, Science, 325, 460–426, 2009. Gordon,~N D., Norris,~J R., Weaver,~C P., and Klein,~S A.: Cluster analysis of cloud regimes and characteristic dynamics of midlatitude synoptic systems in observations and a~model, J. Geophys. Res., 110, D15S17, \doi10.1029/2004JD005027, 2005. Gordon, N. D. and Norris, J. R.: Cluster analysis of midlatitude oceanic cloud regimes: mean cloud and meteorological proper ties, Atmos. Chem. Phys. Discuss., 10, 1559-1593, 2010. Hartigan,~J A.: Clustering Algorithms, Wiley Press, New York, NY, 351~pp., 1975. IPCC Climate Change 2007: The Physical Science Basis, Contribution of Working Group~I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, edited by: Solomon,~S., Qin,~D., Manning,~M., Chen,~Z., Marquis,~M., Averyt,~K B., Tignor,~M., and Miller,~H L., Cambridge University Press, Cambridge, UK and New York, NY, USA, 996~pp., 2007. Jakob,~C. and Tselioudis,~G.: Objective identification of cloud regimes in the Tropical West Pacific, Geophys. Res. Lett., 30(21), 2082, doi:10.1029/2003GL018367, 2003. Jakob,~C., Tselioudis,~G., and Hume~T.: The radiative, cloud and thermodynamic properties of the major Tropical Western Pacific cloud regimes, J. Climate, 18, 1203–1215, 2005. Kalnay,~E., Kanamitsu,~M., Kistler,~R., Collins,~W., Deaven,~D., Gandin,~L., Iredell,~M., Saha,~S., White,~G., Woollen,~J., Zhu,~Y., Chelliah,~M., Ebisuzaki,~W., Higgins,~W., Janowiak,~J., Mo,~K C., Ropelewski,~C., Wang,~J., Leetmaa,~A., Reynolds,~R., Jenne,~R., and Joseph,~D.: The NCEP/NCAR 40-year reanalysis project, B. Am. Meteorol. Soc., 77, 437–470, 1996. Klein,~S A. and Hartmann,~D L.: The seasonal cycle of low stratiform clouds, J. Climate, 6, 1587–1606, 1993. Lau,~N.-C. and Crane,~M W.: A~satellite view of the synoptic-scale organization of cloud cover in midlatitude and tropical circulation systems, Mon. Weather Rev., 123, 1984–2006, 1995. Mitchell,~J F B., Senior,~C A., and Ingram,~W J.: \chemCO_2 and climate: a~missing feedback?, Nature, 341, 132–134, 1989. Norris,~J R.: Low cloud type over the ocean from surface observations, Part~I: Relationship to surface meteorology and the vertical distribution of temperature and moisture, J. Climate, 11, 369–382, 1998. Norris,~J R.: Interannual and interdecadal variability in the storm track, cloudiness, and sea surface temperature over the summertime North Pacific, J. Climate, 13, 422–430, 2000. Norris,~J R. and Leovy,~C B.: Interannual variability in stratiform cloudiness and sea surface temperature, J. Climate, 7, 1915–1925, 1994. Norris,~J R. and Klein,~S A.: Low cloud type over the ocean from surface observations, Part~III: Relationship to vertical motion and the regional surface synoptic environment, J. Climate, 13, 245–256, 2000. Norris,~J R. and Iacobellis,~S F.: North Pacific cloud feedbacks inferred from synoptic-scale dynamic and thermodynamic relationships, J. Climate, 18, 4862–4878, 2005. Ramanathan,~V., Barkstrom,~B R., and Harrison~E F.: Climate and the earth's radiation budget, Phys. Today, 42(5), 22–33, 1989. Raval,~A. and Ramanathan,~V.: Observational determination of the greenhouse effect, Nature, 342, 758–761, 1989. Ringer,~M A., McAvaney,~B J., Andronova,~N., Buja,~L E., Esch,~M., Ingram,~W J., Li,~B., Quaas,~J., Roeckner,~E., Senior,~C A., Soden,~B J., Volodin,~E M., Webb,~M J., and Williams,~K D.: Global mean cloud feedbacks in idealized climate change experiments, Geophys. Res. Lett., 33(7), L07718, doi:10.1029/2005GL025370, 2006. Rossow,~W B., Walker,~A W., Beuschel,~D E., and Roiter,~M D.: International Satellite Cloud Climatology Project (ISCCP) Documentation of New Cloud Datasets, WMO/TD-No 737, World Meteorological Organization, 115~pp., 1996. Rossow,~W B. and Schiffer,~R A.: Advances in understanding ISCCP, B. Am. Meteorol. Soc., 80, 2261–2287, 1999. Soden,~B J. and Held,~I M.: An assessment of climate feedbacks in coupled ocean-atmosphere models, J. Climate, 19, 3354–3360, 2006. Soden,~B J., Held,~I M., Colman,~R., Shell,~K M., Kiehl,~J T., and Shields,~C A.: Quantifying climate feedbacks using radiative kernels, J. Climate, 21, 3504–3520, 2008. Somerville,~R C J. and Remer,~L A.: Cloud optical thickness feedbacks in the \chemCO_2 climate problem, J. Geophys. Res., 89, 9668–9672, 1984. Tian,~B. and Ramanathan,~V.: Role of clouds in surface and atmospheric energy budget, J. Climate, 15, 296–305, 2002. Tselioudis,~G., Rossow,~W B., and Rind,~D.: Global patterns of cloud optical thickness variation with temperature, J. Climate, 5, 1484–1495, 1992. Wagner, T., Beirle, S., Deutschmann, T., Grzegorski, M., and Platt, U.: Dependence of cloud properties derived from spectrally resolved visible satellite observations on surface temperature, Atmos. Chem. Phys., 8, 2299–2312, 2008. Weaver,~C P. and Ramanathan,~V.: The link between summertime cloud radiative forcing and extratropical cyclones in the North Pacific, J. Climate, 9, 2093–2109, 1996. Weaver,~C P. and Ramanathan,~V.: Relationships between large-scale vertical velocity, static stability, and cloud radiative forcing over Northern Hemisphere extratropical oceans, J. Climate, 10, 2871–2887, 1997. Weaver,~C P.: Efficiency of storm tracks an important climate parameter? The role of cloud radiative forcing in poleward heat transport, J. Geophys. Res., 108(D1), 4018, doi:10.1029/2002JD002756, 2003. Webb,~M J., Senior,~C A., Sexton,~D M H., Ingram,~W J., Williams,~K D., Ringer,~M A., McAvaney,~B J., Colman,~R., Soden,~B J., Gudgel,~R., Knutson,~T., Emori,~S., Ogura,~T., Tsushima,~Y., Andronova,~N., Li,~B., Musat,~I., Bony,~S., and Taylor,~K E.: On the contribution of local feedback mechanisms to the range of climate sensitivity in two GCM ensembles, Clim. Dynam., 27(1), 17–38, 2006. Williams~K D. and Tselioudis,~G.: GCM intercomparison of global cloud regimes: Present-day evaluation and climate change response, Clim. Dynam., 29, 231–250, 2007.. Williams,~K D. and Webb,~M J.: A~quantitative performance assessment of cloud regimes in climate models, Clim. Dynam., 33, 141–157, 2009. Zhang,~Y., Rossow,~W B., Lacis,~A A., Oinas,~V., and Mishchenko,~M I.: Calculation of radiative fluxes from the surface to top of atmosphere based on ISCCP and other global data sets: refinements of the radiative transfer model and the input data, J. Geophys. Res., 109, D19105, \doi10.1029/2003JD004457, 2004.