范萌等：Scattering properties of soot-containing particles and their impact by humidity in 1.6 mu m

Scattering properties of soot-containing particles and their impact by humidity in 1.6 mu m
作者:Fan, M (Fan, M.)[ 1,2 ] ; Chen, L (Chen, L.)[ 1 ] ; Xiong, X (Xiong, X.)[ 3 ] ; Li, S (Li, S.)[ 1,4 ] ; Tao, J (Tao, J.)[ 1 ] ; Su, L (Su, L.)[ 1 ] ; Zou, M (Zou, M.)[ 1,2 ] ; Zhang, Y (Zhang, Y.)[ 1 ]
JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER
卷: 134  页: 91-103
DOI: 10.1016/j.jqsrt.2013.11.004
出版年: FEB 2014

摘要
Short-wave infrared (SWIR) band in wavelength near 1.6 mu m is one of the key bands used for satellite observation of Carbon Dioxide (CO2). However, one major uncertainty to use this band for the CO2 retrieval is the scattering by cloud and aerosol particles. To better understand the scattering properties of soot-containing particles in this band, this paper studied the scattering properties for three typical types of soot-containing particles in China: (I) internal mixture, (II) pure soot aggregate, and (III) semi-external 'mixture. Assumed as single non-spherical particle for type I, its scattering property is computed using the T-matrix method combined with the Maxwell-Garnett effective medium theory and the hygroscopic growth theory. For types II and III, a particle-cluster aggregation algorithm is employed to generate fractal-like aggregates, and their scattering properties are computed using the Core-Mantle Generalized Multi-sphere Mie-solution method combined with the hygroscopic growth theory of both monomers and aggregated particles. The simulated results demonstrate that their scattering properties are quite different and strongly impacted by the levels of relative humidity (RH). For type I, the RH plays a much more important role than the morphology in impacting the scattering properties, and the scattering phase functions among different shaped particles have a larger difference for larger particles and higher RH. For type II, both the RH and morphology significantly affect its scattering properties. The single scattering albedo (omega) can be underestimated up to similar to 50% without considering the effects of RH and morphological changes. For type III, its scattering properties mainly depend on the RH and the size of the large water-soluble particle. Although the enlarged soot aggregate, which is attached to a water-soluble particle, almost does not change the light direction, it can result in a significant reduction in omega (similar to 0.15) at low RH for small particles. By comparing the scattering parameters of wet particles at a certain RH level with the dry ones, the impact by the heterogeneity of aerosols generally becomes larger with the increase of RH, but becomes smaller with the increase of particle size. These results suggest that, although the water vapor absorption itself is small in 1.6 pm CO2 band, it can significantly impact the scattering properties of these particles through its effect on the hygroscopic growth of the non-spherical and heterogeneous aerosols. This impact should be taken into account in the retrieval of CO2 using 1.6 mu m as well as other related remote sensing applications. (C) 2013 Elsevier Ltd. All rights reserved.

通讯作者地址: Chen, L (通讯作者)
Chinese Acad Sci, Inst Remote Sensing & Digital Earth, State Key Lab Remote Sensing Sci, POB 9718,20 Datun Rd,Olymp Sci & Technol Pk CAS, Beijing 100101, Peoples R China.
地址:
[ 1 ] Chinese Acad Sci, Inst Remote Sensing & Digital Earth, State Key Lab Remote Sensing Sci, Beijing 100101, Peoples R China
[ 2 ] Univ Chinese Acad Sci, Beijing 100049, Peoples R China
[ 3 ] NOAA, Ctr Satellite Applicat & Res STAR, NESDIS, College Pk, MD 20740 USA
[ 4 ] Emory Univ, Rollins Sch Publ Hlth, Atlanta, GA 30322 USA