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| Titel |
Cloud-scale ice-supersaturated regions spatially correlate with high water vapor heterogeneities |
| VerfasserIn |
M. Diao, M. A. Zondlo, A. J. Heymsfield, L. M. Avallone, M. E. Paige, S. P. Beaton, T. Campos, D. C. Rogers |
| 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. 5 ; Nr. 14, no. 5 (2014-03-14), S.2639-2656 |
| Datensatznummer |
250118482
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| Publikation (Nr.) |
 copernicus.org/acp-14-2639-2014.pdf |
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| Zusammenfassung |
| Cirrus clouds have large yet uncertain impacts on Earth's climate. Ice
supersaturation (ISS) – where the relative humidity with respect to ice
(RHi) is greater than 100% – is the prerequisite condition of ice
nucleation. Here we use 1 Hz (~230 m) in situ, aircraft-based
observations from 87° N to 67° S to analyze the spatial
characteristics of ice-supersaturated regions (ISSRs). The median length of
1-D horizontal ISSR segments is found to be very small (~1 km),
which is 2 orders of magnitude smaller than previously reported. To
understand the conditions of these small-scale ISSRs, we compare individual
ISSRs with their horizontally adjacent subsaturated surroundings and show
that 99% and 73% of the ISSRs are moister and colder, respectively.
When quantifying the contributions of water vapor (H2O) and temperature
(T) individually, the magnitudes of the differences between the maximum RHi
values inside ISSRs (RHimax) and the RHi in subsaturated surroundings
are largely derived from the H2O spatial variabilities (by 88%) than
from those of T (by 9%). These features hold for both ISSRs with and
without ice crystals present. Similar analyses for all RHi horizontal
variabilities (including ISS and non-ISS) show strong contributions from
H2O variabilities at various T, H2O, pressure (P) and various
horizontal scales (~1–100 km). Our results provide a new
observational constraint on ISSRs on the microscale (~100 m)
and point to the importance of understanding how these fine-scale features
originate and impact cirrus cloud formation and the RHi field in the upper
troposphere (UT). |
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