Atmospheric Measurement Techniques www.atmos-meas-tech.net 1867-1381 1867-8548 4 10 2011 10.5194/amt-4-2125-2011 http://www.atmos-meas-tech.net/4/2125/2011/ http://www.atmos-meas-tech.net/4/2125/2011/amt-4-2125-2011.html http://www.atmos-meas-tech.net/4/2125/2011/amt-4-2125-2011.pdf 2125 2142 2011-10-12 First correlated measurements of the shape and light scattering properties of cloud particles using the new Particle Habit Imaging and Polar Scattering (PHIPS) probe A. Abdelmonem ahmed.abdelmonem@kit.edu M. Schnaiter P. Amsler E. Hesse J. Meyer T. Leisner Institute for Meteorology and Climate Research, Karlsruhe Institute of Technology, Karlsruhe, Germany ETH Zurich Institute for Atmospheric and Climate Science, Universitaetstrasse 16, 8092 Zurich, Switzerland Centre for Atmospheric and Instrumentation Research, University of Hertfordshire, Hatfield, AL10 9AB, UK Jülich Research Center, ICG-1, Jülich, Germany Studying the radiative impact of cirrus clouds requires knowledge of the relationship between their microphysics and the single scattering properties of cloud particles. Usually, this relationship is obtained by modeling the optical scattering properties from in situ measurements of ice crystal size distributions. The measured size distribution and the assumed particle shape might be erroneous in case of non-spherical ice particles. We present here a novel optical sensor (the Particle Habit Imaging and Polar Scattering probe, PHIPS) designed to measure simultaneously the 3-D morphology and the corresponding optical and microphysical parameters of individual cloud particles. Clouds containing particles ranging from a few micrometers to about 800 μm diameter in size can be characterized systematically with an optical resolution power of 2 μm and polar scattering resolution of 1° for forward scattering directions (from 1° to 10°) and 8° for side and backscattering directions (from 18° to 170°). The maximum acquisition rates for scattering phase functions and images are 262 KHz and 10 Hz, respectively. Some preliminary results collected in two ice cloud campaigns conducted in the AIDA cloud simulation chamber are presented. PHIPS showed reliability in operation and produced size distributions and images comparable to those given by other certified cloud particles instruments. A 3-D model of a hexagonal ice plate is constructed and the corresponding scattering phase function is compared to that modeled using the Ray Tracing with Diffraction on Facets (RTDF) program. PHIPS is a highly promising novel airborne optical sensor for studying the radiative impact of cirrus clouds and correlating the particle habit-scattering properties which will serve as a reference for other single, or multi-independent, measurement instruments. Amsler, P., Stetzer, O., Schnaiter, M., Hesse, E., Benz, S., Möhler, O., and Lohmann, U.: Ice crystal habits from cloud chamber studies obtained by in-line holographic microscopy related to depolarization measurements, Appl. Optics, 48, 5811–5822, 2009. Baum, B. A., Yang, P., Hu, Y. X., and Feng, Q.: The impact of ice particle roughness on the scattering phase matrix, J. Quant Spectrosc. Ra., 111, 2534–2549, 2010. Baumgardner, D., Jonsson, H., Dawson, W., O'Connor, D., and Newton, R.: The cloud, aerosol and precipitation spectrometer: A new instrument for cloud investigations, Atmos. Res., 59–60, 251–264, 2001. Clarke, A. J. M., Hesse, E., Ulanowski, Z., Kaye, P. H.: A 3D implementation of ray tracing combined with diffraction on facets: Verification and a potential application., J. Quant. Spectrosc. Ra., 100, 103–114, 2006. 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, 1997. Hesse, E.: Modelling diffraction during ray-tracing using the concept of energy flow lines, J. Quant. Spectrosc. Ra., 109, 1374–1383, 2008. Hirst, E., Kaye, P. H., Greenaway, R. S., Field, P., and Johnson, D. W.: Discrimination of micrometre-sized ice and supercooled droplets in mixed-phase cloud, Atmos. Environ., 35, 33–47, 2001. Jourdan, O., Mioche, G., Garrett, T. J., Schwarzenböck, A., Vidot, J., Xie, Y., Shcherbakov, V., Yang, P., and Gayet, J. F.: Coupling of the microphysical and optical properties of an Arctic nimbostratus cloud during the ASTAR~2004 experiment: Implications for light-scattering modeling, J. Geophys. Res., 115, D23206, http://dx.doi.org/10.1029/2010JD014016doi:10.1029/2010JD014016, 2010. Kaye, P. H., Hirst, E., Greenaway, R. S., Ulanowski, Z., Hesse, E., DeMott, P. J., Saunders, C., and Connolly, P.: Classifying atmospheric ice crystals by spatial light scattering, Opt. Lett., 33, 1545–1547, 2008. Lance, S., Brock, C. A., Rogers, D., and Gordon, J. A.: Water droplet calibration of the Cloud Droplet Probe (CDP) and in-flight performance in liquid, ice and mixed-phase clouds during ARCPAC, Atmos. Meas. Tech., 3, 1683–1706, http://dx.doi.org/10.5194/amt-3-1683-2010doi:10.5194/amt-3-1683-2010, 2010. Lawson, P. R., Baker, B. A., Schmitt, C. G., and Jensen, T. L.: An overview of microphysical properties of Arctic clouds observed in May and July~1998 during FIRE~ACE, J. Geophys. Res., 106, 14989–15014, 2001. Libbrecht, K. G.: The physics of snow crystals, Rep. Prog. Phys., 68, 855–895, 2005. Macke, A. and Mishchenko, M. I.: Applicability of regular particle shapes in light scattering calculations for atmospheric ice particles, Appl. Optics, 35, 4291–4296, 1996. Möhler, O., Stetzer, O., Schaefers, S., Linke, C., Schnaiter, M., Tiede, R., Saathoff, H., Krämer, M., Mangold, A., Budz, P., Zink, P., Schreiner, J., Mauersberger, K., Haag, W., Kärcher, B., and Schurath, U.: Experimental investigation of homogeneous freezing of sulphuric acid particles in the aerosol chamber AIDA, Atmos. Chem. Phys., 3, 211–223, http://dx.doi.org/10.5194/acp-3-211-2003doi:10.5194/acp-3-211-2003, 2003. Schnaiter, M., Büttner, S., Vragel, M., and Wagner R.: Influence of particle size and shape on the backscattering linear depolarization ratio of small ice crystals, to be submitted to J. Atmos. Chem. Phys. Discuss., 2011. Schön, R., Schnaiter, M., Ulanowski, Z., Schmitt, C., Benz, S., Möhler, O., Vogt, S., Wagner, R., and Schurath, U.: Particle habit imaging using incoherent light: a first step towards a novel instrument for cloud microphysics, J. Atmos. Ocean. Tech., 28, 493–512, 2011. Shcherbakov, V., Gayet, J.-F., Baker, B., and Lawson, P.: Light Scattering by Single Natural Ice Crystals, Am. Meteorol. Soc., 63, 1513–1525, 2006a. 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, 2006b. Takano, Y. and Liou, K. N.: Radiation transfer in cirrus clouds, Part~III: light scattering by irregular ice crystals, J. Atmos. Sci., 52, 818–837, 1995. Ulanowski, Z. J., Hesse, E., Kaye, P. H., Baran, A. J., and Chandrasekhar, R.: Scattering~29 of light from atmospheric ice analogues, J. Quant. Spectrosc. Ra., 79–80, 1091–1102, 2003. Wagner, R., Linke, C., Naumann, K.-H., Schnaiter, M., Vragel, M., Gangl, M., and Horvath, H.: A review of optical measurements at the aerosol and cloud chamber AIDA, J. Quant. Spectrosc. Ra., 110, 930–949, 2009. Yang, P., Liou, K. N., Wyser, K., and Mitchell, D.: Parameterization of the scattering and absorption properties of individual ice crystals, J. Geophys. Res., 105, 4699–4718, 2000.