利用实验资料检验扁椭球形雨滴和冰粒后向散射DDA算法  

Assessment of DDA for Computing the Backscattering by OblateSpheroidal Particles with Experimental Data

作　　者：许小永[1] 王振会[1] 王庆安[2] 巢增明[3] 

机构地区：[1]南京气象学院电子信息与应用物理系,江苏南京210044 [2]南京大学大气科学系,江苏南京210093 [3]中国航天工业总公司第207研究所,北京100854

出　　处：《高原气象》2002年第1期31-36,共6页Plateau Meteorology

基　　金：国家自然科学基金 ( 4 9875 0 0 7)资助

摘　　要：简要介绍了DDA法理论 ,并根据后向散射截面测量实验所选用的扁椭球形粒子 ,运用DDA法计算了它们在微波段 ,电磁波垂直于粒子旋转轴入射情况下的后向散射截面。经过对比 ,DDA法计算结果与实验测量资料一致性较好。同时评价了DDA算法计算的特点 。The discrete-dipole approximation(DDA) is an important theoretical method for computing scattering and absorption of electromagnetic energy by a particle of arbitrary shape. DDA for scattering calculations, including its validity criteria is briefly presented in this paper. The backscattering cross-sections of liquid and ice oblate spheroids incidented by polarized waves which are propagating vertically to their rotation axis, are calculated by DDA. The theoretical results are compared with the experiment data obtained with a microwave measuring system. It is shown that the theoretical results are consistent with the experiment data in general. As a result, the reliability of theoretical result is proved. Theoretical and experimental analyses indicate that the backscattering ability of raindrops and ice particles presents a curved change as the particle size increases, and fluctuates in the so-called resonance region. It is clear that the computation accuracy of DDA depends mainly on the number %N% of dipoles or the value of the %mkd%. In this article, the technique for the experiment to measure the scattering of simulated raindrop and ice particle is also described.

关 键 词：DDA法 后向散射截面 扁椭球形雨滴 电磁波 大气遥感 冰粒 冰雹 离散偶极子近似 

分 类 号：P426.64[天文地球—大气科学及气象学] P407