红外与激光工程
紅外與激光工程
홍외여격광공정
INFRARED AND LASER ENGINEERING
2014年
5期
1477-1483
,共7页
光散射%大气气溶胶%有效介质理论%内混合
光散射%大氣氣溶膠%有效介質理論%內混閤
광산사%대기기용효%유효개질이론%내혼합
light scattering%aerosol%effective medium theory%internal mixture
利用离散偶极子近似法和Bruggeman有效介质理论,研究了含有黑碳和硫酸盐两种成分的内混合致密气溶胶粒子在尺度参数变化范围为0.1~25时的光学特性,并通过分析比较两种算法计算光学特性的差别研究了有效介质理论对致密内混合粒子光散射的适用性。对单分散系,有效介质理论在瑞利散射区具有较好的适用性,能较好地被用来近似计算内混合粒子的消光、吸收、散射、后向散射效率因子、不对称因子、消光后向散射比和单次散射反照率,相对偏差皆在7%以内;而有效介质理论在米散射区的适用性较差,相对偏差最大可分别达到25%、88%、66%、5000%、42%、1100%和47%,但当内混合体所含的内核较小(体积比1%以内)时仍可以近似使用。在粒子尺度参数大于4时,有效介质理论基本上会低估散射效率因子,却会高估吸收效率因子和不对称因子。而对多分散系,有效介质理论能近似用来计算各光学参量,相对偏差在9%以内。
利用離散偶極子近似法和Bruggeman有效介質理論,研究瞭含有黑碳和硫痠鹽兩種成分的內混閤緻密氣溶膠粒子在呎度參數變化範圍為0.1~25時的光學特性,併通過分析比較兩種算法計算光學特性的差彆研究瞭有效介質理論對緻密內混閤粒子光散射的適用性。對單分散繫,有效介質理論在瑞利散射區具有較好的適用性,能較好地被用來近似計算內混閤粒子的消光、吸收、散射、後嚮散射效率因子、不對稱因子、消光後嚮散射比和單次散射反照率,相對偏差皆在7%以內;而有效介質理論在米散射區的適用性較差,相對偏差最大可分彆達到25%、88%、66%、5000%、42%、1100%和47%,但噹內混閤體所含的內覈較小(體積比1%以內)時仍可以近似使用。在粒子呎度參數大于4時,有效介質理論基本上會低估散射效率因子,卻會高估吸收效率因子和不對稱因子。而對多分散繫,有效介質理論能近似用來計算各光學參量,相對偏差在9%以內。
이용리산우겁자근사법화Bruggeman유효개질이론,연구료함유흑탄화류산염량충성분적내혼합치밀기용효입자재척도삼수변화범위위0.1~25시적광학특성,병통과분석비교량충산법계산광학특성적차별연구료유효개질이론대치밀내혼합입자광산사적괄용성。대단분산계,유효개질이론재서리산사구구유교호적괄용성,능교호지피용래근사계산내혼합입자적소광、흡수、산사、후향산사효솔인자、불대칭인자、소광후향산사비화단차산사반조솔,상대편차개재7%이내;이유효개질이론재미산사구적괄용성교차,상대편차최대가분별체도25%、88%、66%、5000%、42%、1100%화47%,단당내혼합체소함적내핵교소(체적비1%이내)시잉가이근사사용。재입자척도삼수대우4시,유효개질이론기본상회저고산사효솔인자,각회고고흡수효솔인자화불대칭인자。이대다분산계,유효개질이론능근사용래계산각광학삼량,상대편차재9%이내。
Optical properties of compact internal-mixed aerosol particles composed of black carbon coated with sulfate were carried out utilizing discrete dipole approximation (DDA) and Bruggeman effective medium theory for the size parameters from 0.1 to 25. The validity of effective medium theory(EMT) in the light scattering of compact internal mixture was performed based on the comparison of both methods. For the monodisperse particles, the EMT does an adequate job of simulating the extinction-, absorption-, scattering-, backscattering-efficiency factors, asymmetry parameters, extinction-to-backscatter ratios and single scattering albedos in Rayleigh scattering region with all the relative differences less than 7%.Nevertheless, the EMT does not do an adequate job in the range of Mie scattering except for the cases that the inclusions of the internal mixture are small enough with the volume percentage less than 1%. Usage of the EMT can mainly lead to significant underestimations of the scattering efficiency factors but overestimations of absorption efficiency factors and asymmetry parameters when the size parameters are more than 4. For the polydisperse particles, the EMT does an adequate job for the optical parameters with the relative differences less than 9%.