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| Titel |
Ice crystal concentrations in wave clouds: dependencies on temperature, D > 0.5 μm aerosol particle concentration, and duration of cloud processing |
| VerfasserIn |
L. Peng, J. R. Snider, Z. Wang |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 11 ; Nr. 15, no. 11 (2015-06-04), S.6113-6125 |
| Datensatznummer |
250119788
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| Publikation (Nr.) |
 copernicus.org/acp-15-6113-2015.pdf |
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| Zusammenfassung |
| Model equations used to either diagnose or prognose the concentration of
heterogeneously nucleated ice crystals depend on combinations of cloud
temperature, aerosol properties, and elapsed time of supersaturated-vapor or
supercooled-liquid conditions. The validity of these equations has been questioned.
Among many uncertain factors there is a concern that practical limitations on
aerosol particle time of exposure to supercooled-liquid conditions, within ice
nucleus counters, has biased the predictions of a diagnostic model equation. In response to this concern,
this work analyzes airborne measurements of crystals made within the
downwind glaciated portions of wave clouds. A streamline model is used to
connect a measurement of aerosol concentration, made upwind of a cloud, to a
downwind ice crystal (IC) concentration. Four parameters are derived for 80
streamlines: (1) minimum cloud temperature along the streamline, (2) aerosol
particle concentration (diameter, D > 0.5 μm) measured within ascending
air upwind of the cloud, (3) IC concentration measured in descending air
downwind, and (4) the duration of water-saturated conditions along the
streamline. The latter are between 38 and 507 s and the minimum temperatures
are between −34 and −14 °C. Values of minimum temperature, D > 0.5 μm aerosol
concentration, and IC concentration are fitted using the equation developed
for ice nucleating particles (INPs) by by DeMott et al. (2010; D10). Overall, there is
reasonable agreement among measured IC concentrations, INP concentrations
derived using D10's fit equation, and IC concentrations derived by fitting
the airborne measurements with the equation developed by D10. |
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