Show simple item record

contributor authorAckerman, Steven A.
contributor authorSmith, W. L.
contributor authorRevercomb, H. E.
contributor authorSpinhirne, J. D.
date accessioned2017-06-09T16:08:02Z
date available2017-06-09T16:08:02Z
date copyright1990/11/01
date issued1990
identifier issn0027-0644
identifier otherams-61686.pdf
identifier urihttp://onlinelibrary.yabesh.ir/handle/yetl/4202494
description abstractLidar and high spectral resolution infrared radiance observations taken on board the ER-2 on 28 October 1986 are used to study the radiative properties of cirrus cloud in the 8?12 ?m window region. Measurements from the High-spectral resolution Interferometer Sounder (HIS) indicate that the spectral variation of the equivalent blackbody temperature across the window can be greater than 5°C for a given cirrus cloud. This difference is attributed to the presence of small particles. A method for detecting cirrus clouds using 8 ?m, 11 ?m, and 12 ?m bands is presented. The 8 ?m band is centered on a weak water-vapor absorption line while the 11 ?m and 12 ?m bands are between absorption lines. The brightness temperature difference between the 8 and 11 ?m bands is negative for clear regions, while for ice clouds it is positive. Differences in the 11 and 12 ?m channels are positive, whether viewing a cirrus cloud or a clear region. Inclusion of the 8 ?m channel therefore removes the ambiguity associated with the use of 11 and 12 ?m channels alone. The method is based on the comparison of brightness temperatures observed in these three channels. The HIS and lidar observations were combined to derive the spectral effective beam emissivity (?) of the cirrus clouds. Fifty percent of clouds on this day displayed a spectral variation of ? from 2?10%. These differences, in conjunction with large differences in the HIS observed brightness temperatures, indicate that cirrus clouds cannot be considered gray in the 8?12 ?m window region. The derived spectral transmittance of the cloud is used to infer the effective radii of the particle size distribution, assuming ice spheres. For 28 October 1986 the effective radius of cirrus cloud particle size distribution (reff) was generally within the 30?40 ?m range with 8% of the cases where 10 < reff < 30 ?m and 12% of the cases corresponding to rref > 40 ?m.
publisherAmerican Meteorological Society
titleThe 27–28 October 1986 FIRE IFO Cirrus Case Study: Spectral Properties of Cirrus Clouds in the 8–12 μm Window
typeJournal Paper
journal volume118
journal issue11
journal titleMonthly Weather Review
identifier doi10.1175/1520-0493(1990)118<2377:TOFICC>2.0.CO;2
journal fristpage2377
journal lastpage2388
treeMonthly Weather Review:;1990:;volume( 118 ):;issue: 011
contenttypeFulltext


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record