First Ever Satellite Remote Sensing of Small Ice Crystals in Cirrus Clouds:
Application using Published Studies |
Applying the Retrieval Algorithm using Studies from the Published Literature
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Figure from Parol et al., 1991, J. Applied Meteorology
Probability densities of 11-12 µm BTD vs. 11 µm brightness temperature. Curve D describes the average relationship
found by Inoue (1985), where βeff = 1.08. Since βeff inherently contains the same information as the 11 and 12 µm emissivities, the algorithm was reconfigured to retrieve microphysical information from βeff using βeff = 1.08.
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From Giraud et al., 1997 J. Applied Meteorology
An average upper limit for βeff was measured from mid-latitude cirrus over the North Atlantic and Europe, and related to cloud temperature using a split-window retrieval similar in priciple to Inoue's. The above results are statistically significant for this region. It was determined by Giraud et. al. (2001, GRL) that mixed phase conditions begin for T>240°K.
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Algorithm results assuming (1) Inoue's average value of βeff for all temperatures, and
(2) Giraud et al.'s maximum average value of βeff for ice clouds (not mixed phase) for all temperatures. |
Retrieval of the size distribution small-to-large mode ice crystal concentration ratio based on βeff from the Inoue and Parol et al. studies.
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Retrieval of cirrus cloud effective diameter based on βeff from the Inoue and Parol et al. studies.
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Retrieval of cirrus cloud number concentration for constant ice water content (IWC) based on βeff from the Inoue and Parol et al. studies.
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Summary
Assuming βeff is approximately constant with temperature based on the cited studies, the small mode of the ice particle size distribution is generally absent based on this algorithm. Also note that De and number concentration decrease and increase, respectively, around T=-36°C. This appears consistent with the ice nucleation mechanism of homogeneous freezing. |
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