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...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-06-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/16/7251/2016/acp-16-7251-2016.pdf |
| Summary: | 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
(<i>D</i><sub>max</sub>) 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 <i>D</i><sub>max</sub>, near-infrared single-scattering
albedo and asymmetry parameter (<i>g</i>) greater by ∼ 0.2 and 0.05,
respectively. 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 <i>g</i>
primarily attributable to plate aspect ratio. In parcel simulations, ice size
distribution, and <i>g</i> are sensitive to assumed ice properties. |
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| ISSN: | 1680-7316 1680-7324 |