Bulk scattering properties for the remote sensing of ice clouds. Part II: Narrowband models
Bulk scattering properties for the remote sensing of ice clouds. Part II: Narrowband models
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DOI：
10.1175/jam2309.1
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发表时间：
2005-12-01
期刊：
影响因子：
--
通讯作者：
Bedka, ST
中科院分区：
文献类型：
--
作者：
Baum, BA;Yang, P;Bedka, ST
本文研究了第一国际卫星云气体学计划区域实验（FIRE） i、FIRE- ii、大气辐射测量计划密集观测期、热带降雨测量任务夸贾林岛实验（KWAJEX）所获得的1117个粒径分布的单散射特性，包括单散射反照率、不对称因子和相位函数的发展。以及热带砧层和卷云层的卷云区域研究（CRYSTAL）佛罗里达地区卷云实验（FACE）数据。研究的主要重点是开发适合地球观测系统Terra和Aqua平台上中分辨率成像光谱仪（MODIS）成像仪使用的波段平均模型，特别是波长为0.65、1.64、2.13和3.75 μ m的波段。研究结果表明，在深对流区域形成的冰云的体散射特性与在上升气流速度低得多的区域形成的冰云存在很大差异。从冰晶习惯的颗粒大小依赖的混合物中获得的带平均体散射特性结果与仅假设固体六方柱的结果进行了比较。在1.64-、2.13-和3.75-gm波段，六角形柱的单散射反照率低于习惯混合柱的单散射反照率，差异随波长增加而增大。在0.65 μ m处，习惯混合物和纯六方柱的不对称系数差异最大，随波长的增加，差异减小。在凌晨3点75分，两种习惯假设产生的不对称因素几乎无法区分。并与MODIS version-1 （V1）模型进行了非对称系数、单散射反照率和散射相函数的比较。当前模型和V1模型之间的差异可以追溯到微物理模型，特别是尺寸分布中假设的最小和最大颗粒的数量。
This study examines the development of bulk single-scattering properties of ice clouds, including single-scattering albedo, asymmetry factor, and phase function, for a set of 1117 particle size distributions obtained from analysis of the First International Satellite Cloud Climatology Project Regional Experiment (FIRE)-I, FIRE-II, Atmospheric Radiation Measurement Program intensive observation period, Tropical Rainfall Measuring Mission Kwajalein Experiment (KWAJEX), and the Cirrus Regional Study of Tropical Anvils and Cirrus Layers (CRYSTAL) Florida Area Cirrus Experiment (FACE) data. The primary focus is to develop band-averaged models appropriate for use by the Moderate Resolution Imaging Spectroradiometer (MODIS) imager on the Earth Observing System Terra and Aqua platforms, specifically for bands located at wavelengths of 0.65, 1.64, 2.13, and 3.75 mu m. The results indicate that there are substantial differences in the bulk scattering properties of ice clouds formed in areas of deep convection and those that exist in areas of much lower updraft velocities. Band-averaged bulk scattering property results obtained from a particle-size-dependent mixture of ice crystal habits are compared with those obtained assuming only solid hexagonal columns. The single-scattering albedo is lower for hexagonal columns than for a habit mixture for the 1.64-, 2.13-, and 3.75-gm bands, with the differences increasing with wavelength. In contrast, the asymmetry factors obtained from the habit mixture and only the solid hexagonal column are most different at 0.65 mu m, with the differences decreasing as wavelength increases. At 3.75 Am, the asymmetry factor results from the two habit assumptions are almost indistinguishable. The asymmetry factor, single-scattering albedo, and scattering phase functions are also compared with the MODIS version-1 (V1) models. Differences between the current and V1 models can be traced to the microphysical models and specifically to the number of both the smallest and the largest particles assumed in the size distributions.