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| Titel |
Radiative consequences of low-temperature infrared refractive indices for supercooled water clouds |
| VerfasserIn |
P. M. Rowe, S. Neshyba, V. P. Walden |
| 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 ; 13, no. 23 ; Nr. 13, no. 23 (2013-12-09), S.11925-11933 |
| Datensatznummer |
250085864
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| Publikation (Nr.) |
 copernicus.org/acp-13-11925-2013.pdf |
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| Zusammenfassung |
| Simulations of cloud radiative properties for climate modeling and
remote sensing rely on accurate knowledge of the complex refractive
index (CRI) of water. Although conventional algorithms employ
a temperature-independent assumption (TIA), recent infrared
measurements of supercooled water have demonstrated that the CRI
becomes increasingly ice-like at lower temperatures. Here, we assess
biases that result from ignoring this temperature dependence. We
show that TIA-based cloud retrievals introduce spurious ice into
pure, supercooled clouds, or underestimate cloud optical thickness and
droplet size. TIA-based downwelling radiative fluxes are lower than
those for the temperature-dependent CRI by as much as
1.7 W m−2 (in cold regions), while top-of-atmosphere
fluxes are higher by as much as 3.4 W m−2 (in warm
regions). Proper accounting of the temperature dependence of the
CRI, therefore, leads to significantly greater local greenhouse
warming due to supercooled clouds than previously predicted. The
current experimental uncertainty in the CRI at low temperatures must
be reduced to account for supercooled clouds properly in both
climate models and cloud-property retrievals. |
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