红外波在沙尘暴中的后向散射增强

Backscattering enhancement for infrared wave in sand and dust storm

为了提高沙尘暴中红外系统的精度,应用电磁波在离散随机介质中传播的多重散射理论,分析红外波在沙尘暴中传播时的后向散射增强机理,给出了沙尘暴单位体积的粒子数随能见度变化的关系式,对于可见到远红外波,研究其在不同能见度的沙尘暴中传播时的多重散射效应引起的后向散射增强。结果表明对于不同波长的波,其后向散射增强不同。沙尘暴的能见度越低,后向散射增强越显著。不同类型的沙尘暴,粒子尺度分布不同;在一定能见度时,单位体积中粒子数越多的沙尘暴,后向散射增强越大;在一定的粒子数密度时,含大粒子数越多的沙尘暴,后向散射增强越显著,尤其是波长较长波的后向散射增强更明显。即,沙尘暴的能见度越低,单位体积中的粒子数越多,包含较大粒子数目较多时,后向散射和增强就越显著,则对红外系统的影响就越严重。

In order to improve the precision of infrared systems in sand and dust storms, by using the multiple scattering theory of electromagnetic wave propagation in discrete random medium, the backscattering enhancement mechanism was analyzed for infrared wave propagating in sand and dust storms. The formula about the relation of the particle number per unit volume and atmosphere visibility was presented in sand and dust storms. From visible light to far infrared wave, the backscattering enhancement caused by multiple scattering in sand and dust storms was researched for different visibilities. The results show that the backscattering enhancement for different wavelength waves is different. The lower visibility in sand and dust storms, the stronger backscattering enhancement is. For different types of sand and dust storms, the particle size distribution is different. At a given visibility, the particle number per unit volume is larger, the backscattering enhancement are stronger. At a given particle number density, the number of the larger size particles is larger, the backscattering enhancement is stronger. Especially, the enhancement for the longer wavelength wave is more obvious. That is, the lower visibility, the larger number per unit volume, and the more the larger size particles, the backscattering and enhancement is stronger in sand and dust storms, and the effect on infrared systems is severer.