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| Titel |
A comprehensive parameterization of heterogeneous ice nucleation of dust surrogate: laboratory study with hematite particles and its application to atmospheric models |
| VerfasserIn |
N. Hiranuma, M. Paukert, I. Steinke, K. Zhang, G. Kulkarni, C. Hoose, M. Schnaiter, H. Saathoff, O. Möhler |
| 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 ; 14, no. 23 ; Nr. 14, no. 23 (2014-12-10), S.13145-13158 |
| Datensatznummer |
250119229
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| Publikation (Nr.) |
 copernicus.org/acp-14-13145-2014.pdf |
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| Zusammenfassung |
| A new heterogeneous ice nucleation parameterization that covers a wide
temperature range (−36 to −78 °C) is presented. Developing and
testing such an ice nucleation parameterization, which is constrained through
identical experimental conditions, is important to accurately simulate the
ice nucleation processes in cirrus clouds. The ice nucleation active
surface-site density (ns) of hematite particles, used as a proxy
for atmospheric dust particles, were derived from AIDA (Aerosol Interaction
and Dynamics in the Atmosphere) cloud chamber measurements under water
subsaturated conditions. These conditions were achieved by continuously
changing the temperature (T) and relative humidity with respect to ice
(RHice) in the chamber. Our measurements showed several different
pathways to nucleate ice depending on T and RHice conditions.
For instance, almost T-independent freezing was observed at
−60 °C < T < −50 °C, where RHice
explicitly controlled ice nucleation efficiency, while both T and
RHice played roles in other two T regimes:
−78 °C < T < −60 °C and
−50 °C < T < −36 °C. More specifically,
observations at T lower than −60 °C revealed that higher
RHice was necessary to maintain a constant ns, whereas
T may have played a significant role in ice nucleation at T higher than
−50 °C. We implemented the new hematite-derived ns
parameterization, which agrees well with previous AIDA measurements of desert
dust, into two conceptual cloud models to investigate their sensitivity to
the new parameterization in comparison to existing ice nucleation schemes for
simulating cirrus cloud properties. Our results show that the new AIDA-based
parameterization leads to an order of magnitude higher ice crystal
concentrations and to an inhibition of homogeneous nucleation in lower-temperature regions. Our cloud simulation results suggest that atmospheric
dust particles that form ice nuclei at lower temperatures, below
−36 °C, can potentially have a stronger influence on cloud
properties, such as cloud longevity and initiation, compared to previous
parameterizations. |
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