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Title: Derivation of physical and optical properties of mid-latitude cirrus ice crystals for a size-resolved cloud microphysics model

Single-crystal images collected in mid-latitude cirrus are analyzed to provide internally consistent ice physical and optical properties for a size-resolved cloud microphysics model, including single-particle mass, projected area, fall speed, capacitance, single-scattering albedo, and asymmetry parameter. Using measurements gathered during two flights through a widespread synoptic cirrus shield, bullet rosettes are found to be the dominant identifiable habit among ice crystals with maximum dimension ( D max) greater than 100 µm. Properties are therefore first derived for bullet rosettes based on measurements of arm lengths and widths, then for aggregates of bullet rosettes and for unclassified (irregular) crystals. Derived bullet rosette masses are substantially greater than reported in existing literature, whereas measured projected areas are similar or lesser, resulting in factors of 1.5–2 greater fall speeds, and, in the limit of large D max, near-infrared single-scattering albedo and asymmetry parameter ( g) greater by ~0.2 and 0.05, respectively. Furthermore, a model that includes commonly imaged side plane growth on bullet rosettes exhibits relatively little difference in microphysical and optical properties aside from ~0.05 increase in mid-visible g primarily attributable to plate aspect ratio. In parcel simulations, ice size distribution, and g are sensitive to assumed ice properties.
 [1] ;  [2] ;  [3] ;  [4] ;  [4] ;  [1] ;  [2] ;  [5]
  1. NASA Goddard Inst. for Space Studies, New York, NY (United States)
  2. Univ. of Chicago, Chicago, IL (United States)
  3. NASA Goddard Inst. for Space Studies, New York, NY (United States); Columbia Univ., New York, NY (United States)
  4. Univ. of Illinois, Urbana-Champaign, IL (United States)
  5. Spec Inc., Boulder, CO (United States)
Publication Date:
Grant/Contract Number:
SC0006988; SC0008500; SC001406; AC02-05CH11231; SC0014065
Published Article
Journal Name:
Atmospheric Chemistry and Physics (Online)
Additional Journal Information:
Journal Name: Atmospheric Chemistry and Physics (Online); Journal Volume: 16; Journal Issue: 11; Journal ID: ISSN 1680-7324
European Geosciences Union
Research Org:
NASA Goddard Inst. for Space Studies (GISS), New York, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
54 ENVIRONMENTAL SCIENCES; single-scattering properties; general hydrodynamic theory; large-eddy simulations; in-situ observations; radiative properties; part i; climate models; water-content; fall speeds; terminal velocities
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1288211