Characteristics of Titan's stratospheric aerosols and condensate clouds from Cassini CIRS far-infrared spectra
Characteristics of Titan's stratospheric aerosols and condensate clouds from Cassini CIRS far-infrared spectra
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DOI：
10.1016/j.icarus.2007.04.003
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发表时间：
2007-11-01
期刊：
影响因子：
3.2
通讯作者：
Taylor, F. W.
中科院分区：
文献类型：
--
作者：
de Kok, R.;Irwin, P. G. J.;Taylor, F. W.
在卡西尼复合红外光谱仪（CIRS）的远红外临边光谱中发现了四个广泛的光谱特征，其中两个以前从未被发现过。这些特征比光谱分辨率更广泛，这表明它们是由土卫六平流层中的微粒造成的。我们在这里推导出65 ° S和85 ° N之间的六个纬度上这四个特征的光谱特性和随高度的变化。泰坦的主要气溶胶在这里被称为Haze 0。它存在于远红外线中的所有波数处，并且被发现具有分数尺度高度（即，气溶胶密度标度高度除以大气密度标度高度）在1.5和1.7之间，北部的不透明度略有增加。第二个特征约为140 cm（-1）（雾度A），具有与雾度0相似的空间特性，但具有1.2-1.3的较小分数尺度高度。Haze 0和Haze A在100 km以下的反演丰度都有所增加。另外两个特征（霾B在220 cm（-1）附近，霾C在190 cm（-1）附近）在其密度分布中分别在140和90 km处具有大的最大值。与南半球相比，北方半球的霾B要丰富得多。霾C也显示向北大幅增加，但随后在北纬85度消失。(C)2007年爱思唯尔公司All rights reserved.
Four broad spectral features were identified in far-infrared limb spectra from the Cassini Composite Infrared Spectrometer (CIRS), two of which have not been identified before. The features are broader than the spectral resolution, which suggests that they are caused by particulates in Titan's stratosphere. We derive here the spectral properties and variations with altitude for these four features for six latitudes between 65 degrees S and 85 degrees N. Titan's main aerosol is called Haze 0 here. It is present at all wavenumbers in the far-infrared and is found to have a fractional scale height (i.e., the aerosol density scale height divided by the atmospheric density scale height) between 1.5 and 1.7 with a small increase in opacity in the north. A second feature around 140 cm(-1) (Haze A) has similar spatial properties to Haze 0, but has a smaller fractional scale height of 1.2-1.3. Both Haze 0 and Haze A show an increase in retrieved abundance below 100 km. Two other features (Haze B around 220 cm(-1) and Haze C around 190 cm(-1)) have a large maximum in their density profiles at 140 and 90 km, respectively. Haze B is much more abundant in the northern hemisphere compared to the southern hemisphere. Haze C also shows a large increase towards the north, but then disappears at 85 degrees N. (C) 2007 Elsevier Inc. All rights reserved.