ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-11-5853-2011 Thin and subvisible cirrus and contrails in a subsaturated environment Kübbeler M. 1 5 Hildebrandt M. 1 6 Meyer J. 1 Schiller C. 1 Hamburger Th. 2 Jurkat T. 2 Minikin A. 2 Petzold A. 2 Rautenhaus M. 2 Schlager H. 2 Schumann U. 2 Voigt C. 2 3 Spichtinger P. 3 Gayet J.-F. 4 Gourbeyre C. 4 Krämer M. 1 Forschungszentrum Jülich, Inst. for Energy and Climate Research, IEK-7, Jülich, Germany DLR Oberpfaffenhofen, Inst. Atmos. Physics, Weßling, Germany Univ. Mainz, Inst. Atmos. Physics, Mainz, Germany Univ. Blaise Pascal, LaMP, Clermont-Ferrand, France now at: ETH Zürich, Inst. Atmos. & Climate, Zürich, Switzerland now at: IUTA, Air Quality Dep., Duisburg, Germany 22 06 2011 11 12 5853 5865 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/11/5853/2011/acp-11-5853-2011.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/11/5853/2011/acp-11-5853-2011.pdf

The frequency of occurrence of cirrus clouds and contrails, their life time, ice crystal size spectra and thus their radiative properties depend strongly on the ambient distribution of the relative humidity with respect to ice (RH<sub>ice</sub>). Ice clouds do not form below a certain supersaturation and both cirrus and contrails need at least saturation conditions to persist over a longer period. Under subsaturated conditions, cirrus and contrails should dissipate. During the mid-latitude aircraft experiment CONCERT 2008 (CONtrail and Cirrus ExpeRimenT), RH<sub>ice</sub> and ice crystals were measured in cirrus and contrails. Here, we present results from 2.3/1.7 h of observation in cirrus/contrails during 6 flights. Thin and subvisible cirrus with contrails embedded therein have been detected frequently in a subsaturated environment. Nevertheless, ice crystals up to radii of 50 μm and larger, but with low number densities were often observed inside the contrails as well as in the cirrus. Analysis of the meteorological situation indicates that the crystals in the contrails were entrained from the thin/subvisible cirrus clouds, which emerged in frontal systems with low updrafts. From model simulations of cirrus evaporation times it follows that such thin/subvisible cirrus can exist for time periods of a couple of hours and longer in a subsaturated environment and thus may represent a considerable part of the cirrus coverage.

 References Borrmann, S., Luo, B., and Mishchenko, M.: Application of the T-matrix method to the measurement of aspherical (ellipsoidal) particles with forward scattering optical particle counters., J. Aerosol Sci., 31, 89–799, 2000. Bunz, H., Benz, S., Gensch, I., and Krämer, M.: MAID: a model to simulate UT/LS aerosols and ice clouds, Environ. Res. Lett., 3, 035001, http://dx.doi.org/10.1088/1748-9326/3/3/035001doi:10.1088/1748-9326/3/3/035001, 2008. Burkhardt, U., Kärcher, B., and Schumann, U.: Global modeling of the contrail and contrail cirrus climate impact, B. Am. Meteorol. Soc., 91, 479–484, http://dx.doi.org/10.1175/2009BAMS2656.1doi:10.1175/2009BAMS2656.1, 2010. de Reus, M., Borrmann, S., Bansemer, A., Heymsfield, A. J., Weigel, R., Schiller, C., Mitev, V., Frey, W., Kunkel, D., Kürten, A., Curtius, J., Sitnikov, N. M., Ulanovsky, A., and Ravegnani, F.: Evidence for ice particles in the tropical stratosphere from in-situ measurements, Atmos. Chem. Phys., 9, 6775–6792, http://dx.doi.org/10.5194/acp-9-6775-2009doi:10.5194/acp-9-6775-2009, 2009. DeMott, P J., Cziczo, D., Prenni, A., Murphy, D., Kreidenweis, S., Thomson, D., Borys, R., and Rogers, D.: Measurements of the concentration and composition of nuclei for cirrus formation, P. Natl. Acad. Sci. USA, 100, 14660–14655, 2003. DeMott, P J., Prenni, A J., Liu, X., Kreidenweis, S M., Petters, M D., Twohy, C H., Richardson, M S., Eidhammer, T., and Rogers, D C.: Predicting global atmospheric ice nuclei distributions and their impacts on climate, P. Natl. Acad. Sci. USA, 107, 11217–11222, http://dx.doi.org/10.1073/pnas.0910818107doi:10.1073/pnas.0910818107, 2010. Febvre, G., Gayet, J.-F., Minikin, A., Schlager, H., Shcherbakov, V., Jourdan, O., Busen, R., Fiebig, M., Kärcher, B., and Schumann, U.: On optical and microphysical characteristics of contrails and cirrus, J. Geophys. Res., 114, D02204, http://dx.doi.org/10.1029/2008JD010184doi:10.1029/2008JD010184, 2009. Forster, P. and Rogers, H.: Metrics for comparison of climate impacts from well mixed greenhouse gases and inhomogeneous forcing such as those from UT/LS ozone, contrails and contrail cirrus, Aviation Climate Change Research Initiative (ACCRI), 1–57, 2008. Gayet, J.-F., Asano, S., Yamazaki, A., Uchiyama, A., Sinyuk, A., Jourdan, O., and Auriol, F.: Two case studies of winter continental-type water and mixed-phase stratocumuli over the sea 1. Microphysical and optical properties, J. Geophys. Res., 107, 4569, http://dx.doi.org/10.1029/2001JD001106doi:10.1029/2001JD001106, 2002a. 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, 2230, http://dx.doi.org/10.1029/2001GL014342doi:10.1029/2001GL014342, 2002b. Gensch, I., Bunz, H., Baumgardner, D., Christensen, L., Fahey, D., Hermann, R., Lawson, P., Popp, P., Smith, J., Webster, C., Weinstock, E., Wilson, J., Peter, T., and Krämer, M.: Supersaturations, microphysics and nitric acid partitioning in a cold cirrus observed during CR-AVE 2006: an observation-modeling intercomparison study., Environ. Res. Lett., 3, 035003, http://dx.doi.org/10.1088/1748-9326/3/3/035003doi:10.1088/1748-9326/3/3/035003, 2008. Gettelman, A., Fetzer, E., Eldering, A., and Irion, F.: The Global Distribution of Supersaturation in the Upper Troposphere from the Atmospheric Infrared Sounder, J. Climate, 19, 6089–6103, 2006. Gierens, K. and Spichtinger, P.: On the size distribution of ice-supersaturated regions in the upper troposphere and lowermost stratosphere, Ann. Geophys., 18, 499–504, http://dx.doi.org/10.1007/s00585-000-0499-7doi:10.1007/s00585-000-0499-7, 2000. Gierens, K., Schumann, U., Helten, M., Smit, H., and Marenco, A.: A distribution law for relative humidity in the upper troposphere and lower stratosphere derived from three years of MOZAIC measurements, Ann. Geophys., 17, 1218-1226, http://dx.doi.org/10.1007/s00585-999-1218-7doi:10.1007/s00585-999-1218-7, 1999. Gierens, K., Schumann, U., Helten, M., Smit, H., and Wang, P.: Ice-supersaturated regions and subvisible cirrus in the northern midlatitude upper troposphere , J. Geophys. Res., 105, 22743–22753, 2000. Immler, F., Treffeisen, R., Engelbart, D., Krüger, K., and Schrems, O.: Cirrus, contrails, and ice supersaturated regions in high pressure systems at northern mid latitudes, Atmos. Chem. Phys., 8, 1689–1699, http://dx.doi.org/10.5194/acp-8-1689-2008doi:10.5194/acp-8-1689-2008, 2008. Jensen, E., Toon, O., Kinne, S., Sachse, G., Anderson, B., Chan, K., Twohy, C., Gandrud, B., Heymsfield, A., and Miake-Lye, R.: Environmental conditions required for contrail formation and persistence, J. Geophys. Res., 103, 3929–3936, 1998. Jensen, E., Toon, O., Vay, S., Ovarlez, J., May, R., Bui, T. P., Twohy, Gandrud, B., Pueschel, R. F., and Schumann, U.: Prevalence of ice-supersaturated regions in the upper troposphere: Implications for optically thin ice cloud formation, J. Geophys. Res., 106, 17253–17266, 2001. Koop, T.: Homogeneous ice nucleation in water and aqueous solutions, Z. Phys. Chem., 218, 1231–1258, 2004. 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. Korolev, A., Emery, E., Strapp, J., Cober, S., Isaac, G., Wasey, M., and Marcotte, D.: Small ice particles in tropospheric clouds: fact or artifact? Airborne Icing Instrumentation Evaluation Experiment, B. Am. Meteorol. Soc., 92, http://dx.doi:10.1175/2010BAMS3141.1doi:10.1175/2010BAMS3141.1, 2011. Krämer, M. and Hildebrandt, M.: The role of heterogeneous freezing in cirrus formation: new model sensitivity studies, AMS Cloud Physics Conference, Portland, USA, 2010. Krämer, M., Schiller, C., Afchine, A., Bauer, R., Gensch, I., Mangold, A., Schlicht, S., Spelten, N., Sitnikov, N., Borrmann, S., de Reus, M., and Spichtinger, P.: Ice supersaturations and cirrus cloud crystal numbers, Atmos. Chem. Phys., 9, 3505–3522, http://dx.doi.org/10.5194/acp-9-3505-2009doi:10.5194/acp-9-3505-2009, 2009 Kärcher, B.: Properties of subvisible cirrus clouds formed by homogeneous freezing, Atmos. Chem. Phys., 2, 161–170, http://dx.doi.org/10.5194/acp-2-161-2002doi:10.5194/acp-2-161-2002, 2002. Kärcher, B. and Lohmann, U.: A parameterization of cirrus cloud formation: homogeneous freezing of supercooled aerosols, J. Geophys. Res., 107, 4010, http://dx.doi.org/10.1029/2002JD003220doi:10.1029/2002JD003220, 2002. Kärcher, B. and Lohmann, U.: A parameterization of cirrus cloud formation: heterogeneous freezing, J. Geophys. Res., 108, 4402, http://dx.doi.org/10.1029/2002JD003220doi:10.1029/2002JD003220, 2003. Marti, J. and Mauersberger, K.: A survey and new measurements of ice vapour pressure at temperatures between 170 K and 250 K, Geophys. Res. Lett., 20, 363–366, 1993. Nelson, J.: Sublimation of Ice Crystals, J. Atmos. Sci., 55, 910–919, 1998. Petzold, A., Busen, R., Schröder, F., Baumann, R., Kuhn, M., Ström, J., Hagen, D., Whitefield, P., Baumgardner, D., Arnold, F., Borrmann, S., and Schumann, U.: Near-Field measurements on contrail properties from fuels with different sulfur content, J. Geophys. Res., 102, 29867–29880, 1997. Pruppacher, H. and Klett, J.: Microphysics of Clouds and Precipitation, Kluwer Academic, 2nd edn., 1997. Sassen, K., Griffin, M K., and Dodd, G C.: Optical Scattering and Microphysical Properties of Subvisual Cirrus Clouds, and Climatic Implications, J. Appl. Meteorol., 28, 91–98, 1989. Schiller, C., Krämer, M., Afchine, A., Spelten, N., and Sitnikov, N.: The ice water content in Arctic, midlatitude and tropical cirrus, J. Geophys. Res., 113, D24208, http://dx.doi:10.1029/2008JD010342.doi:10.1029/2008JD010342., 2008. Schlager, H., Konopka, P., Schulte, P., Schumann, U., Ziereis, H., Arnold, F., Klemm, M., Hagen, D E., Whitefield, P D., and Ovarlez, J.: In situ observations of air traffic emission signatures in the North Atlantic flight corridor, J. Geophys. Res., 102, 10739–10750, http://dx.doi.org/10.1029/96JD03748doi:10.1029/96JD03748, 1997. Schröder, F., Kärcher, B., Duroure, C., Ström, J., Petzold, A., Gayet, J.-F., Strauss, B., Wendling, P., and Borrmann, S.: On the transition of contrails into cirrus clouds, J. Atmos. Sci., 57, 464–480, 2000. Schumann, U.: On conditions for contrail formation from aircraft exhaust, Meteorol. Zeitschrift, 5, 4–23, 1996. Schumann, U., Schlager, H., Arnold, F., Baumann, R., Hachberger, P., and Klemm, O.: Dilution of aircraft exhaust plumes at cruise altitudes, Atmos. Environ., 32, 3097–3103, 1998. Schumann, U., Mayer, B., Gierens, K., Unterstrasser, S., Jessberger, P., Petzold, A., and Voigt, C.: Effective radius of ice particles in cirrus and contrails, J. Atmos. Sci., 68, 300–321, http://dx.doi.org/10.1175/2010JAS3562.1doi:10.1175/2010JAS3562.1, 2010. Solomon, S., Qin, D., Manning, M., Marquis, M., Averyt, K., Tignor, M. M B., Miller~Jr., R., L., H., and Chen, Z. E.: Climate change 2007, The physical science basis, Cambridge University press, 1st edn., 2007. Spichtinger, P. and Cziczo, D J.: Impact of heterogeneous ice nuclei on homogeneous freezing events, J. Geophys. Res., 115, D14208, http://dx.doi:10.1029/2009JD012168doi:10.1029/2009JD012168, 2010. Spichtinger, P., Gierens, K., and Read, W.: The global distribution of ice supersaturated regions as seen by the microwave limb sounder., Q. J. Roy. Meteor. Soc., 129, 3391–3410, 2003. Voigt, C., Schlager, H., Ziereis, H., Kärcher, B., Luo, B., Schiller, C., Krämer, M., Popp, P., Irie, H., and Kondo, Y.: Nitric acid in cirrus clouds, Geophys. Res. Lett., 33, L05803, http://dx.doi:10.1029/2005GL025159doi:10.1029/2005GL025159, 2006. Voigt, C., Schumann, U., Jurkat, T., Schäuble, D., Schlager, H., Petzold, A., Gayet, J.-F., Krämer, M., Schneider, J., Borrmann, S., Schmale, J., Jessberger, P., Hamburger, T., Lichtenstern, M., Scheibe, M., Gourbeyre, C., Meyer, J., Kübbeler, M., Frey, W., Kalesse, H., Butler, T., Lawrence, M. G., Holzäpfel, F., Arnold, F., Wendisch, M., Döpelheuer, A., Gottschaldt, K., Baumann, R., Zöger, M., Sölch, I., Rautenhaus, M., and Dörnbrack, A.: In-situ observations of young contrails – overview and selected results from the CONCERT campaign, Atmos. Chem. Phys., 10, 9039–9056, http://dx.doi.org/10.5194/acp-10-9039-2010doi:10.5194/acp-10-9039-2010, 2010. Zöger, M., Afchine, A., Eicke, N., Gerhards, M.-T., Klein, E., McKenna, D., Mörschel, U., Schmidt, U., Tan, V., Tuitjer, F., Woyke, T., and Schiller, C.: Fast in situ stratospheric hygrometers: A new family of balloon-borne and airborne Lyman- photofragment fluorescence hygrometers, J. Geophys. Res., 104, 1807–1816, 1999.