Small Cloud Particle Shapes in Mixed-Phase Clouds

Greg M. McFarquhar Department of Atmospheric Sciences, University of Illinois at Urbana–Champaign, Urbana, Illinois

Search for other papers by Greg M. McFarquhar in
Current site
Google Scholar
PubMed
Close
,
Junshik Um Department of Atmospheric Sciences, University of Illinois at Urbana–Champaign, Urbana, Illinois

Search for other papers by Junshik Um in
Current site
Google Scholar
PubMed
Close
, and
Robert Jackson Department of Atmospheric Sciences, University of Illinois at Urbana–Champaign, Urbana, Illinois

Search for other papers by Robert Jackson in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

The shapes of cloud particles with maximum dimensions Dmax between 35 and 60 μm in mixed-phase clouds were studied using high-resolution particle images collected by a cloud particle imager (CPI) during the Mixed-Phase Arctic Cloud Experiment (M-PACE) and the Indirect and Semi-Direct Aerosol Campaign (ISDAC). The area ratio α, the projected area of a particle divided by the area of a circle with diameter Dmax, quantified particle shape. The differing optical characteristics of CPIs used in M-PACE and ISDAC had no effect on derived α provided that Dmax > 35 μm and CPI focus > 45. The fraction of particles with 35 < Dmax < 60 μm with α > 0.8 increased with the ratio of liquid water content (LWC) to total water content (TWC). The average αmean of small particles in each 10-s interval in mixed-phase clouds was correlated with LWC/TWC with a correlation coefficient of 0.60 for M-PACE and 0.43 for ISDAC. The stronger correlation seen during M-PACE was most likely associated with the presence of more liquid droplets that were larger than the CPI detection threshold contributing to αmean; the modal effective radius was larger (11 vs 6 μm), and drops with D > 35 μm had concentrations during M-PACE that were 6 times as large as those of ISDAC. This study hence suggests that area ratio can be used to identify the phase of particles with 35 < Dmax < 60 μm and questions the assumption used in previous studies that all particles in this size range are supercooled droplets.

Corresponding author address: Prof. Greg McFarquhar, Dept. of Atmospheric Sciences, University of Illinois at Urbana–Champaign, 105 S. Gregory Street, MC 223, Urbana, IL 61801. E-mail: mcfarq@atmos.uiuc.edu

Abstract

The shapes of cloud particles with maximum dimensions Dmax between 35 and 60 μm in mixed-phase clouds were studied using high-resolution particle images collected by a cloud particle imager (CPI) during the Mixed-Phase Arctic Cloud Experiment (M-PACE) and the Indirect and Semi-Direct Aerosol Campaign (ISDAC). The area ratio α, the projected area of a particle divided by the area of a circle with diameter Dmax, quantified particle shape. The differing optical characteristics of CPIs used in M-PACE and ISDAC had no effect on derived α provided that Dmax > 35 μm and CPI focus > 45. The fraction of particles with 35 < Dmax < 60 μm with α > 0.8 increased with the ratio of liquid water content (LWC) to total water content (TWC). The average αmean of small particles in each 10-s interval in mixed-phase clouds was correlated with LWC/TWC with a correlation coefficient of 0.60 for M-PACE and 0.43 for ISDAC. The stronger correlation seen during M-PACE was most likely associated with the presence of more liquid droplets that were larger than the CPI detection threshold contributing to αmean; the modal effective radius was larger (11 vs 6 μm), and drops with D > 35 μm had concentrations during M-PACE that were 6 times as large as those of ISDAC. This study hence suggests that area ratio can be used to identify the phase of particles with 35 < Dmax < 60 μm and questions the assumption used in previous studies that all particles in this size range are supercooled droplets.

Corresponding author address: Prof. Greg McFarquhar, Dept. of Atmospheric Sciences, University of Illinois at Urbana–Champaign, 105 S. Gregory Street, MC 223, Urbana, IL 61801. E-mail: mcfarq@atmos.uiuc.edu
Save
  • Borys, R. D., D. H. Lowenthal, S. A. Cohn, and W. O. J. Brown, 2003: Mountaintop and radar measurements of anthropogenic aerosol effects on snow growth and snowfall rate. Geophys. Res. Lett., 30, 1538, doi:10.1029/2002GL016855.

    • Search Google Scholar
    • Export Citation
  • Brenguier, J.-L., H. Pawlowska, and L. J. Schuller, 2003: Cloud microphysical and radiative properties for parameterization and satellite monitoring of the indirect effect of aerosol on climate. J. Geophys. Res., 108, 8632, doi:10.1029/2002JD002682.

    • Search Google Scholar
    • Export Citation
  • Cober, S. G., G. A. Isaac, and A. V. Korolev, 2001a: Assessing the Rosemount Icing Detector with in situ measurements. J. Atmos. Oceanic Technol., 18, 515528.

    • Search Google Scholar
    • Export Citation
  • Cober, S. G., G. A. Isaac, A. V. Korolev, and J. W. Strapp, 2001b: Assessing cloud-phase conditions. J. Appl. Meteor., 40, 19671983.

  • Cooper, W. A., 1977: Cloud physics investigation by the University of Wyoming in HIPLEX 1977. Bureau of Reclamation Rep. AS 199, 321 pp.

  • Cotton, R., S. Osborne, Z. Ulanowski, E. Hirst, P. H. Kaye, and R. S. Greenaway, 2010: The ability of the Small Ice Detector (SID-2) to characterize cloud particle and aerosol morphologies obtained during flights of the FAAM BAe-146 research aircraft. J. Atmos. Oceanic Technol., 27, 290303.

    • Search Google Scholar
    • Export Citation
  • Curry, J. A., 1995: Interactions among aerosols, clouds, and climate of the Arctic Ocean. Sci. Total Environ., 160, 777791.

  • DeMott, P. J., and Coauthors, 2010: Predicting global atmospheric ice nuclei distributions and their impacts on climate. Proc. Natl. Acad. Sci. USA, 107, 11 21711 222.

    • Search Google Scholar
    • Export Citation
  • Dong, X., and G. G. Mace, 2003: Arctic stratus cloud properties and radiative forcing derived from ground-based data collected at Barrow, Alaska. J. Climate, 16, 445461.

    • Search Google Scholar
    • Export Citation
  • Dong, X., G. G. Mace, P. Minnis, and D. F. Young, 2001: Arctic stratus cloud properties and their effect on the surface radiation budget: Selected cases from FIRE ACE. J. Geophys. Res., 106, 15 29715 312.

    • Search Google Scholar
    • Export Citation
  • Earle, M. E., P. S. K. Liu, J. W. Strapp, A. Zelenyuk, D. Imre, G. M. McFarquhar, N. C. Shantz, and W. R. Leaitch, 2011: Factors influencing the microphysics and radiative properties of liquid-dominant Arctic clouds: Insight from observations of aerosol and clouds during ISDAC. J. Geophys. Res., 116, D00T09, doi:10.1029/2011JD015887.

    • Search Google Scholar
    • Export Citation
  • Field, P. R., R. Wood, P. R. A. Brown, P. H. Kaye, E. Hirst, R. Greenaway, and J. A. Smith, 2003: Ice particle interarrival times measured with a fast FSSP. J. Atmos. Oceanic Technol., 20, 249261.

    • Search Google Scholar
    • Export Citation
  • Field, P. R., R. J. Hogan, P. R. A. Brown, A. J. Illingworth, T. W. Choularton, P. H. Kaye, E. Hirst, and R. Greenaway, 2004: Simultaneous radar and aircraft observations of mixed-phase cloud at the 100 m scale. Quart. J. Roy. Meteor. Soc., 130, 18771904.

    • Search Google Scholar
    • Export Citation
  • Field, P. R., A. J. Heymsfield, and A. Bansemer, 2006: Shattering and particle interarrival times measured by optical array probes in ice clouds. J. Atmos. Oceanic Technol., 23, 13571371.

    • Search Google Scholar
    • Export Citation
  • Fleishauer, R. P., V. E. Larson, and T. H. Vonder Haar, 2002: Observed microphysical structure of midlevel, mixed-phase clouds. J. Atmos. Sci., 59, 17791804.

    • Search Google Scholar
    • Export Citation
  • Gayet, J. F., G. Febvre, and H. Larsen, 1996: The reliability of the PMS FSSP in the presence of small ice crystals. J. Atmos. Oceanic Technol., 13, 13001310.

    • Search Google Scholar
    • Export Citation
  • Gayet, J. F., O. Crepal, J. F. Fournol, and S. Oshchepkov, 1997: A new airborne nephelometer for measurements of optical and microphysical cloud properties. Part I: Theoretical design. Ann. Geophys., 15, 451459.

    • Search Google Scholar
    • Export Citation
  • Girard, E., J. P. Blanchet, and Y. Dubois, 2005: Effects of Arctic sulphuric acid aerosols on wintertime low-level atmospheric ice crystals, humidity and temperature at Alert, Nunavut. Atmos. Res., 73, 131148.

    • Search Google Scholar
    • Export Citation
  • Han, Q., W. B. Rossow, and A. A. Lacis, 1994: Near-global survey of effective droplet radii in liquid water clouds using ISCCP data. J. Climate, 7, 465497.

    • Search Google Scholar
    • Export Citation
  • Harrington, J. Y., and P. Q. Olsson, 2001: On the potential influence of ice nuclei on surface-forced marine stratocumulus cloud dynamics. J. Geophys. Res., 106, 27 47327 484.

    • Search Google Scholar
    • Export Citation
  • Harrington, J. Y., T. Reisin, W. R. Cotton, and S. M. Kreidenweis, 1999: Cloud resolving simulations of Arctic stratus. Part II: Transition-season clouds. Atmos. Res., 51, 4575.

    • Search Google Scholar
    • Export Citation
  • Heymsfield, A. J., and G. M. McFarquhar, 2002: Mid-latitude and tropical cirrus microphysical properties. Cirrus, D. Lynch, Ed., Optical Society of America, 78–101.

  • Intrieri, J. M., C. W. Fairall, M. D. Shupe, P. O. G. Persson, E. L Andreas, P. S. Guest, and R. E. Moritz, 2002a: An annual cycle of Arctic surface cloud at SHEBA. J. Geophys. Res., 107, 8039, doi:10.1029/2000JC000439.

    • Search Google Scholar
    • Export Citation
  • Intrieri, J. M., M. D. Shupe, T. Uttal, and B. J. McCarty, 2002b: An annual cycle of Arctic cloud characteristics observed by radar and lidar at SHEBA. J. Geophys. Res., 107, 8030, doi:10.1029/2000JC000423.

    • Search Google Scholar
    • Export Citation
  • Jackson, R. C., and Coauthors, 2012: The dependence of ice microphysics on aerosol concentration in Arctic mixed-phase stratus clouds during ISDAC and M-PACE. J. Geophys. Res., 117, D15207, doi:10.1029/2012JD017668.

    • Search Google Scholar
    • Export Citation
  • Jiang, H., W. R. Cotton, J. O. Pinto, J. A. Curry, and M. J. Weissbluth, 2000: Cloud resolving simulations of mixed-phase Arctic stratus observed during BASE: Sensitivity to concentration of ice crystals and large-scale heat and moisture advection. J. Atmos. Sci., 57, 21052117.

    • Search Google Scholar
    • Export Citation
  • Korolev, A. V., and G. A. Isaac, 2003: Roundness and aspect ratio of particles in ice clouds. J. Atmos. Sci., 60, 17951808.

  • Korolev, A. V., and G. A. Isaac, 2005: Shattering during sampling by OAPs and HVPS. Part I: Snow particles. J. Atmos. Oceanic Technol., 22, 528542.

    • Search Google Scholar
    • Export Citation
  • Korolev, A. V., G. A. Isaac, S. G. Cober, J. W. Strapp, and J. Hallett, 2003: Microphysical characterization of mixed-phase clouds. Quart. J. Roy. Meteor. Soc., 129, 3965.

    • Search Google Scholar
    • Export Citation
  • Korolev, A. V., J. W. Strapp, G. A. Isaac, and E. Emery, 2008: Improved airborne hot-wire measurements of ice water content in clouds. Preprints, 15th Int. Conf. on Clouds and Precipitation, Cancun, Mexico, ICCP, P13.4.

  • Korolev, A. V., E. Emery, J. W. Strapp, S. G. Cober, G. A. Isaac, M. Wasey, and D. Marcotte, 2011: Small ice particles in tropospheric clouds: Fact or artifact? Airborne icing instrumentation evaluation experiment. Bull. Amer. Meteor. Soc., 92, 967973.

    • Search Google Scholar
    • Export Citation
  • Lawson, R. P., 2011: Effects of ice particles shattering on the 2D-S probe. Atmos. Meas. Tech., 4, 13611381.

  • Lawson, R. P., B. A. Baker, C. G. Schmitt, and T. L. Jensen, 2001: An overview of microphysical properties of Arctic clouds observed in May and July 1998 during FIRE ACE. J. Geophys. Res., 106, 14 98915 014, doi:10.1029/2000JD900789.

    • Search Google Scholar
    • Export Citation
  • Lohmann, U., 2002: A glaciation indirect aerosol effect caused by soot aerosols. Geophys. Res. Lett., 29, 1052, doi:10.1029/2001GL014357.

    • Search Google Scholar
    • Export Citation
  • Martin, G. M., D. W. Johnson, and A. Spice, 1994: The measurement and parameterization of effective radius of droplets in warm stratocumulus. J. Atmos. Sci., 51, 18231842.

    • Search Google Scholar
    • Export Citation
  • Mazin, I. P., A. V. Korolev, A. Heymsfield, G. A. Isaac, and S. G. Cober, 2001: Thermodynamics of icing cylinder for measurements of liquid water content in supercooled clouds. J. Atmos. Oceanic Technol., 18, 543558.

    • Search Google Scholar
    • Export Citation
  • McFarquhar, G. M., and A. J. Heymsfield, 1996: Microphysical characteristics of three cirrus anvils sampled during the Central Equatorial Pacific Experiment (CEPEX). J. Atmos. Sci., 53, 24012423.

    • Search Google Scholar
    • Export Citation
  • McFarquhar, G. M., and S. G. Cober, 2004: Single-scattering properties of mixed-phase Arctic clouds at solar wavelengths: Impacts on radiative transfer. J. Climate, 17, 37993813.

    • Search Google Scholar
    • Export Citation
  • McFarquhar, G. M., A. J. Heymsfield, A. Macke, J. Iaquinta, and S. M. Aulenbach, 1999: Use of observed ice crystal sizes and shapes to calculate mean-scattering properties and multispectral radiances: CEPEX April 4, 1993, case study. J. Geophys. Res., 104, 31 76331 779.

    • Search Google Scholar
    • Export Citation
  • McFarquhar, G. M., J. Um, M. Freer, D. Baumgardner, G. L. Kok, and G. Mace, 2007a: Importance of small ice crystals to cirrus properties: Observations from the Tropical Warm Pool International Cloud Experiment (TWP-ICE). Geophys. Res. Lett., 34, L13803, doi:10.1029/2007GL029865.

    • Search Google Scholar
    • Export Citation
  • McFarquhar, G. M., G. Zhang, M. R. Poellot, G. L. Kok, R. McCoy, T. Tooman, A. Fridlind, and A. J. Heymsfield, 2007b: Ice properties of single-layer stratocumulus during the Mixed-Phase Arctic Cloud Experiment: 1. Observations. J. Geophys. Res., 112, D24201, doi:10.1029/2007JD008633.

    • Search Google Scholar
    • Export Citation
  • McFarquhar, G. M., and Coauthors, 2011: Indirect and Semi-Direct Aerosol Campaign (ISDAC): The impact of Arctic aerosols on clouds. Bull. Amer. Meteor. Soc., 92, 183201.

    • Search Google Scholar
    • Export Citation
  • Morrison, H., M. D. Shupe, and J. A. Curry, 2003: Modeling clouds observed at SHEBA using a bulk microphysics parameterization implemented into a single-column model. J. Geophys. Res., 108, 4255, doi:10.1029/2002JD002229.

    • Search Google Scholar
    • Export Citation
  • Nousiainen, T., and G. M. McFarquhar, 2004: Light scattering by quasi-spherical ice crystals. J. Atmos. Sci., 61, 22292248.

  • Peng, Y., U. Lohmann, W. R. Leaitch, C. Banic, and M. Couture, 2002: The cloud albedo–cloud droplet effective radius relationship for clean and polluted clouds from RACE and FIRE.ACE. J. Geophys. Res., 107, 4106, doi:10.1029/2000JD000281.

    • Search Google Scholar
    • Export Citation
  • Pinto, J. O., 1998: Autumnal mixed-phased cloudy boundary layers in the Arctic. J. Atmos. Sci., 55, 20162038.

  • Rangno, A. L., and P. V. Hobbs, 2001: Ice particles in stratiform clouds in the Arctic and possible mechanisms for the production of high ice concentrations. J. Geophys. Res., 106, 15 06515 075.

    • Search Google Scholar
    • Export Citation
  • Shcherbakov, V., J.-F. Gayet, O. Jourdan, J. Strom, and A. Minikin, 2006: Light scattering by single ice crystals of cirrus clouds. Geophys. Res. Lett., 33, L15809, doi:10.1029/2006GL026055.

    • Search Google Scholar
    • Export Citation
  • Shupe, M. D., 2011: Clouds at Arctic atmospheric observatories. Part II: Thermodynamic phase characteristics. J. Appl. Meteor. Climatol., 50, 645661.

    • Search Google Scholar
    • Export Citation
  • Shupe, M. D., T. Uttal, S. Matrosov, and A. S. Frisch, 2001: Cloud water contents and hydrometeor sizes during the FIRE Arctic Clouds Experiment. J. Geophys. Res., 106, 15 01515 028.

    • Search Google Scholar
    • Export Citation
  • Sun, Z., and K. P. Shine, 1994: Studies of the radiative properties of ice and mixed-phase clouds. Quart. J. Roy. Meteor. Soc., 120, 111137.

    • Search Google Scholar
    • Export Citation
  • Um, J., and G. M. McFarquhar, 2011: Dependence of the single-scattering properties of small ice crystals on idealized shape models. Atmos. Chem. Phys., 11, 31593171.

    • Search Google Scholar
    • Export Citation
  • Um, J., G. M. McFarquhar, P. Connolly, C. Emersic, J. Z. Ulanowski, and M. Gallagher, 2012: Calibration of three generations of Cloud Particle Imagers (CPIs) to improve measurements of particle size distributions. Preprints, 16th Int. Conf. on Clouds and Precipitation, Leipzig, Germany, ICCP, 12.1.2.

    • Search Google Scholar
    • Export Citation
  • Verlinde, J., and Coauthors, 2007: The Mixed-Phase Arctic Cloud Experiment. Bull. Amer. Meteor. Soc., 88, 205221.

  • Zuidema, P., and Coauthors, 2005: An Arctic springtime mixed-phase cloudy boundary layer observed during SHEBA. J. Atmos. Sci., 62, 160176.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 526 134 8
PDF Downloads 369 98 3