ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-12-8963-2012 Some effects of ice crystals on the FSSP measurements in mixed phase clouds Febvre G. 1 Gayet J.-F. 1 Shcherbakov V. 1 2 Gourbeyre C. 1 Jourdan O. 1 Laboratoire de Météorologie Physique, UMR6016, CNRS/Université Blaise Pascal, Clermont-Ferrand, France LaMP, Institut Universitaire de Technologie d'Allier, Montluçon, France 01 10 2012 12 19 8963 8977 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/12/8963/2012/acp-12-8963-2012.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/12/8963/2012/acp-12-8963-2012.pdf

In this paper, we show that in mixed phase clouds, the presence of ice crystals may induce wrong FSSP 100 measurements interpretation especially in terms of particle size and subsequent bulk parameters. The presence of ice crystals is generally revealed by a bimodal feature of the particle size distribution (PSD). The combined measurements of the FSSP-100 and the Polar Nephelometer give a coherent description of the effect of the ice crystals on the FSSP-100 response. The FSSP-100 particle size distributions are characterized by a bimodal shape with a second mode peaked between 25 and 35 μm related to ice crystals. This feature is observed with the FSSP-100 at airspeed up to 200 m s<sup>−1</sup> and with the FSSP-300 series. In order to assess the size calibration for clouds of ice crystals the response of the FSSP-100 probe has been numerically simulated using a light scattering model of randomly oriented hexagonal ice particles and assuming both smooth and rough crystal surfaces. The results suggest that the second mode, measured between 25 μm and 35 μm, does not necessarily represent true size responses but corresponds to bigger aspherical ice particles. According to simulation results, the sizing understatement would be neglected in the rough case but would be significant with the smooth case. Qualitatively, the Polar Nephelometer phase function suggests that the rough case is the more suitable to describe real crystals. Quantitatively, however, it is difficult to conclude. A review is made to explore different hypotheses explaining the occurrence of the second mode. However, previous cloud in situ measurements suggest that the FSSP-100 secondary mode, peaked in the range 25–35 μm, is likely to be due to the shattering of large ice crystals on the probe inlet. This finding is supported by the rather good relationship between the concentration of particles larger than 20 μm (hypothesized to be ice shattered-fragments measured by the FSSP) and the concentration of (natural) ice particles (CPI data). In mixed cloud, a simple estimation of the number of ice crystals impacting the FSSP inlet shows that the ice crystal shattering effect is the main factor in observed ice production.

 References Ashenden, R. and Marwitz, J. D.: Characterizing the supercooled large droplet environment with corresponding turboprop aircraft response, J. Aircraft, 35, 912–920, 1998. Baumgardner, D., Dye, J. E., Gandrud, B. W., and Knollenberg, R. G.: Interpretation of measurements made by the Forward Scattering Spectrometer Probe (FSSP-300) during the Airborne Arctic Stratospheric Expedition, J. Geophys. Res., 97, 8035–8046, 1992. Baumgardner, D., Gayet, J.-F., Gerber, H., Korolev, A. V., and Twohy, C.: Clouds/Measurement Techniques In Situ, in: Encyclopedia of Atmospheric Sciences, edited by: Holton, J. R., Curry, J. A., and Pyle, J., Academic Press, London, 4000 pp., 2002. Baumgardner, D., Brenguier, J. L., Bucholtz, A., Coe, H., DeMott, P., Garrett, T. J., Gayet, J. F., Hermann, M., Heymsfield, A., Korolev, A., Krämer, M., Petzold, A., Strapp, W., Pilewskie, P., Taylor, J., Twohy, C., Wendisch, M., Bachalo, W., and Chuang, P.: Airborne instruments to measure atmospheric aerosol particles, clouds and radiation: A cook's tour of mature and emerging technology, Atmos. Res., 102, 10–29, doi:10.1016/j.atmosres.2011.06.021, 2011. 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, 789–799, 2000. Cober, S. G. and Isaac, G. A.: Characterization of Aircraft Icing Environments with Supercooled Large Drops for Application to Commercial Aircraft Certification, J. Appl. Meteorol. Climatol., 51, 265–284, 2012. Cober, S. G., Isaac, G. A., and Strapp, J. W.: Aircraft icing measurements in east coast winter storms, J. Appl. Meteor., 34, 88–100, 1995. Cober, S. G., Korolev, A. V., Strapp, J. W., and Marcotte, D. L.: Measurements of aircraft icing environments which include supercooled large drops, 37th Aerospace Sci. Meeting, Reno, NV, AIAA Paper 99-0494, 1999. Cober, S. G., Isaac, G. A., Korolev, A. V., and Strapp, J. W.: Assessing Cloud-Phase Conditions, J. Appl. Meteor., 40, 1967–1983, 2001. Crépel, O., Gayet, J.-F., Fournol, J.-F., and Oshchepkov, S.: A new airborne Polar Nephelometer for the measurement of optical and microphysical cloud properties. Part II: Preliminary tests, Ann. Geophys., 15, 460–470, http://dx.doi.org/10.1007/s00585-997-0460-0doi:10.1007/s00585-997-0460-0, 1997. Dye, J. E. and Baumgardner, D.: Evaluation of the Forward Scattering Spectrometer Probe, Part I: Electronic and Optical Studies, J. Atmos. Ocean. Technol., 4, 329–344, 1984. Engvall, A.-C., Krejci, R., Ström, J., Treffeisen, R., Scheele, R., Hermansen, O., and Paatero, J.: Changes in aerosol properties during spring-summer period in the Arctic troposphere, Atmos. Chem. Phys., 8, 445–462, http://dx.doi.org/10.5194/acp-8-445-2008doi:10.5194/acp-8-445-2008, 2008. Field, P. R., Wood, R., Brown, P. R. A., Kaye, P. H., Hirst, E., Greenaway, R., and Smith, J. A.: Ice particle interarrival times measured with a Fast FSSP, J. Atmos. Sci., 20, 249–261, 2003. Field, P. R., Heymsfield, A. J., and Bansemer, A.: Shattering and interarrival times measured by optical array probes in ice clouds, J. Atmos. Ocean. Tech., 23, 1357–1371, 2006. Fugal, J. P. and Shaw, R. A.: Cloud particle size distributions measured with an airborne digital in-line holographic instrument, Atmos. Meas. Tech., 2, 259–271, http://dx.doi.org/10.5194/amt-2-259-2009doi:10.5194/amt-2-259-2009, 2009. Gardiner, B. A. and Hallett, J.: Degradation of In-Cloud Forward Scattering Spectrometer Probe Measurements in the Presence of Ice Particles, J. Atmos. Ocean. Tech., 2, 171–180, 1985 Garrett, T. J., Hobbs, P. V., and Gerber, H.: Shortwave, single-scattering properties of arctic ice clouds, J. Geophys. Res., 106, 15155–15172, 2001. Gayet, J.-F., Febvre, G., and Larsen, H.: On the reliability of the PMS FSSP probe in the presence of small ice crystals, J. Atmos. Ocean. Tech., 13, 1300–1310, 1996. Gayet, J. F., Crépel, O., Fournol, J. F., and Oshchepkov, S.: A new airborne polar Nephelometer for the measurements of optical and microphysical cloud properties. Part I: Theoretical design, Ann. Geophys., 15, 451–459, http://dx.doi.org/10.1007/s00585-997-0451-1doi:10.1007/s00585-997-0451-1, 1997. Gayet, J.-F., Auriol, F., Oshchepkov, S., Schröder, F., Duroure, C., Febvre, G., Fournol, J.-F., Crépel, O., Personne, P., and Daugeron, D.: In situ measurements of the scattering phase function of stratocumulus, contrails and cirrus, Geophys. Res. Lett., 25, 971–974, 1998. Gayet, J.-F., Asano, S., Yamazaki, A., Uchiyama, A., Sinyuk, A., Jourdan, O., and Auriol, F.: Two case studies of continental-type water and maritime mixed-phased stratocumuli over the sea. Part I~: Microphysical and Optical propertie, J. Geophys. Res., 107, D21, doi:10.1029/2001JD001106, 2002. Gayet, J.-F., Mioche, G., Dörnbrack, A., Ehrlich, A., Lampert, A., and Wendisch, M.: Microphysical and optical properties of Arctic mixed-phase clouds. The 9 April 2007 case study., Atmos. Chem. Phys., 9, 6581–6595, http://dx.doi.org/10.5194/acp-9-6581-2009doi:10.5194/acp-9-6581-2009, 2009. Gayet, J.-F., Shcherbakov, V., Voigt, C., Schumann, U., Schäuble, D., Jessberger, P., Petzold, A., Minikin, A., Schlager, H., Dubovik, O., and Lapyonok, T.: The evolution of microphysical and optical properties of an A380 contrail in the vortex phase, Atmos. Chem. Phys., 12, 6629–6643, http://dx.doi.org/10.5194/acp-12-6629-2012doi:10.5194/acp-12-6629-2012, 2012. Heymsfield, A. J.: On measurements of small ice particles in clouds, Geophys. Res. Lett., 34, L23812, http://dx.doi.org/10.1029/2007GL030951doi:10.1029/2007GL030951, 2007. Ivanova, D. C., Mitchell, D. L., Arnott, W. P., and Poellot, M.: A GCM parameterization for bimodal size spectra and ice mass removal rates in mid-latitude cirrus clouds, Atmos. Res., 59, 89–113, 2001. Ivanova, D. C., Mitchell, D. L., and McFarquhar, G. M.: A trimodal Size Distribution Parametrization for tropical Cirrus Clouds, Fourteenth ARM Science Team Meeting Proceedings, Albuquerque, New Mexico, 22–26 March, 2004. Jensen, E. J., Lawson, P., Baker, B., Pilson, B., Mo, Q., Heymsfield, A. J., Bansemer, A., Bui, T. P., McGill, M., Hlavka, D., Heymsfield, G., Platnick, S., Arnold, G. T., and Tanelli, S.: On the importance of small ice crystals in tropical anvil cirrus, Atmos. Chem. Phys., 9, 5519–5537, http://dx.doi.org/10.5194/acp-9-5519-2009doi:10.5194/acp-9-5519-2009, 2009. Jourdan, O., Mioche, G., Garret, T. J., Schwarzenbock, A., Vidot, J., Xie, Y., Shcherbakov, V., Duroure, C., Yang, P., and Gayet, J.-F.: Coupling of the microphysical and optical properties of arctic clouds during the ASTAR 2004 experiment: Implications for light scattering modelling, J. Geophys. Res., 115, D23206, http://dx.doi.org/10.1029/2010JD014016doi:10.1029/2010JD014016, 2010. King, W. D.: Air Flow and Particle Trajectories around Aircraft Fuselages. IV: Orientation of Ice Crystals, J. Atmos. Ocean. Technol., 3, 433–439, 1986. Knollenberg, R. G.: The optical array: An alternative to scattering or extinction for airborne particle size determination, J. Appl. Meteor., 9, 86–103, 1970. Knollenberg, R. G.: Techniques for probing cloud microstructure, Clouds: Their formation, optical properties and effects, edited by: Hobbs, P. V. and Deepak, A., Academic Press, 495. pp., 1981. Korolev, A. V. and Isaac, G. A.: Shattering during sampling by OAPs and HVPS, Part I: Snow particles, J. Atmos. Ocean. Tech., 22, 528–543, 2005. Korolev, A., Isaac, G. A., Cober, S. G., Strapp, J. W., and Hallett, J.: Microphysical charaterisation of mixed-phase clouds, Q. J. R. Meteorol. Soc., 129, 39–65, 2003. Korolev, A., Emery, E., Strapp, W., Cober, S., Isaac, G., Wasey, M., and Cober, S. G.: Small ice particles in tropospheric clouds: fact or artifact?, Airborne Icing Instrumentation Evaluation Experiment, B. Am. Meteorol. Soc., 92, 967–973, http://dx.doi.org/10.1175/2010BAMS3141.1doi:10.1175/2010BAMS3141.1, 2011. Law, K. S., Ancellet, G., Pelon, J., Turquety, S., Clerbaux, C., Pommier, M., de Villiers, R., Gayet, J.-F., Schwarzeboeck, A., Nedelec, P., Schneider, J., and Borrmann, S., 2008 : POLARCAT-France Airborne Experiment: first results, Intern. Global Atmospheric Chemistry conference (IGAC), Annecy, France, 7–12 September, 2008. Lawson, R. P.: Effects of ice particles shattering on the 2D-S probe, Atmos. Meas. Tech., 4, 1361–1381, http://dx.doi.org/10.5194/amt-4-1361-2011doi:10.5194/amt-4-1361-2011, 2011. Lawson, R. P., Baker, B. A., and Schmitt, C. G.: An overview of microphysical properties of Arctic clouds observed in May and July 1998 during FIRE ACE, J. Geophys. Res., 106, 14989–15014, 2001. Lawson, R. P., O'Connor, D., Zmarzly, P., Weaver, K., Baker, B. A., Mo, Q., and Jonsson, H.: The 2D-S (Stereo) probe: Design and preliminary tests of a new airborne, high-speed, high-resolution imaging probe, J. Atmos. Ocean. Technol., 23, 1462–1477, http://dx.doi.org/10.1175/JTECH1927.1doi:10.1175/JTECH1927.1, 2006. MacPherson, J. I. and Baumgardner, D.: Airflow about King Air Wingtip-Mounted Cloud Particle Measurement Probes, J. Atmos. Ocean. Technol., 5, 259–273, 1988. McFarquhar, G., Zhang, G., Poellot, M. R., Kok, G. L., McCoy, R., Tooman, T., Fridlind, A., and Heymsfield, A.: Ice properties of single-layer stratocumulus during the Mixed-Phase Arctic Cloud Experiment, J. Geophys. Res., 112, D24201, http://dx.doi.org/10.1029/2007JD008633doi:10.1029/2007JD008633, 2007. Miller, D., Ratvasky, T., Bernstein, B., McDonough, F., and Strapp, J. W.: NASA/FAA/NCAR supercooled large droplet icing flight research: Summary of winter 96–97 flight operations, AIAA 36th Aerospace Sci. Meeting and Exhibit, Reno, NV, AIAA Paper 98-0577, 1998. Mishchenko, M. I., Travis, L. D., Kahn, R. A., and West, R. A.:~Modeling phase functions for dustlike tropospheric aerosols using a shape mixture of randomly oriented polydisperse spheroids, J. Geophys. Res., 102, 16831–16847, 1997. Mitchell, D. L., Arnott, W. P., Schmitt, C., Lowenthal, D., and Edwards, J. M.: A fundamental difference between ice crystal and cloud droplet absorption: photon tunneling effects, 10th Conference on Atmospheric Radiation: A Symposium with Tributes to the Works of Verner E. Suomi, AMS, Madison, WI, 28 June–2 July 1999. Nagel, D., Maixner, U., Strapp, W., and Wasey, M.: Advancements in Techniques for Calibration and Characterization of In Situ Optical Particle Measuring Probes, and Applications to the FSSP-100 Probe, J. Atmos. Ocean Tech., 24, 745–760, 2007. Niu, J., Carey, L. D., Yang, P., Vonder Haar, T. H.: Optical properties of a vertically inhomogeneous mid-latitude mid-level mixed-phase altocumulus in the infrared region, Atmos. Res., 88, 234–242, 2008. Pinnick, R. G., Garvey, D. M., and Duncan, L. D.: Calibration of Knollenberg FSSP Light-Scattering Counters for Measurement of Cloud Droplets, J. Appl. Meteor., 20, 1049–1057, 1981. Protat, A., McFarquhar, G., Um, J., and Delano\"e, J.: Obtaining best estimates for the microphysical and radiative properties of tropical ice clouds from TWP-ICE in-situ microphysical observations, J. Appl. Meteor. Clim., 50, 895–915, http://dx.doi.org/10.1175/2010JAMC2401.1doi:10.1175/2010JAMC2401.1, 2010. \hack Riley, J. T.: Mixed-phase icing conditions: A review. Airport and Aircraft Safety Research and Development Rep. DOT/ FAA/AR-98/76, Federal Aviation Administration, Atlantic City, NJ, 45 pp., 1998. Sassen, K. and Liou, K. N.: Scattering and polarized laser light by water droplets, mixed- phase and ice crystal clouds, Part I: Angular scattering patterns, J. Atmos. Sci., 36, 838–851, 1979. Shcherbakov, V., Gayet, J.-F., Jourdan, O., Ström, J., and Minikin, A.: Light scattering by single ice crystals of cirrus clouds, Geophys. Res. Lett., 33, L15809, http://dx.doi.org/10.1029/2006GL026055doi:10.1029/2006GL026055, 2006. Shcherbakov, V., Gayet, J.-F., Febvre, G., Heymsfield, A. J., and Mioche, G.: Probabilistic model of shattering effect on in-cloud measurements, Atmos. Chem. Phys. Discuss., 10, 11009–11045, http://dx.doi.org/10.5194/acpd-10-11009-2010doi:10.5194/acpd-10-11009-2010, 2010. Vidaurre, G. and Hallett, J.: Particle Impact and Breakup in Aircraft Measurement, J. Atmos. Ocean Tech., 26, 972–983, http://dx.doi.org/10.1175/2008JTECHA1147.1doi:10.1175/2008JTECHA1147.1, 2009. Warren, S. G. and Brandt, R. E.: Optical constants of ice from the ultraviolet to the microwave: A revised compilation, J. Geophys. Res., 113, D14220, http://dx.doi.org/10.1029/2007JD009744doi:10.1029/2007JD009744, 2008. Yang, P. and Liou, K. N.: Geometric-optics-integral-equation method for light scattering by nonspherical ice crystals, Appl. Opt., 35, 6568–6584, 1996. Yang, P. and Liou, K. N.: Single-scattering properties of complex ice crystals in terrestrial atmosphere, Contrib. Atmos. Phys., 71, 223–248, 1998. Zhang, Z., Yang, P., Kattawar, G. W., and Wiscombe, W. J.: Single-scattering properties of Platonic solids in geometrical-optics regime, J. Q. S. R. Trans., 106, 595–603, 2007.