对非球形冰晶94GHz云雷达后向散射和衰减的研究  

Back scattering and attenuation of non-spherical ice crystals with 94 GHz millimeter-wavelength

作　　者：吴举秀[1] 魏鸣[2] 黄磊[1] 涂爱琴[1] 刘彬[1] 

机构地区：[1]山东省气象局大气探测技术保障中心,济南250031 [2]南京信息工程大学,气象灾害省部共建教育部重点实验室,南京210044

出　　处：《气象科学》2016年第1期63-70,共8页Journal of the Meteorological Sciences

基　　金：公益性行业(气象)科研专项(GYHY201206038,GYHY201306040,GYHY201406033);江苏省高校自然科学重大基础研究项目(10KJA170030);灾害天气国家重点实验室开放课题(2010LASW-A01);江苏省自然科学研究基金资助项目(BK2012466);北极阁基金(BJG201208,BJG201102);山东省气象局面上课题(2015sdqxm13);国家自然科学基金资助项目(41305031);江苏高校优势学科建设工程资助项目(PAPD)

摘　　要：针对94 GHz毫米波云雷达的数据处理,基于离散偶极子近似法(DDA)计算了几种非球形冰晶的后向散射及衰减效率,探讨了不同冰云模型下冰云的雷达反射率因子(Z_e)和衰减系数(k)及冰水含量(IWC,记作W)的关系。结果表明:(1)形状对冰晶的散射及衰减效率与粒子大小有关。(2)在实际的冰云中,将六角形冰晶和椭圆冰晶看做同体积的球形粒子将低估其衰减和后向散射。将聚合物冰晶看做等体积球形,将高估其后向散射及衰减,子弹花冰晶的后向散射与同体积的球形相比有减小也有增大,但是衰减比同体积球形的小。(3)冰云模型对Z_e-k、Z_e-W关系具有较大影响,假设滴谱相同的条件下,得到了具体冰云模型下对应Z_e-k、Z_e-W关系的系数。这些探讨为我国W波段云雷达的数据处理提供了参考。Aiming at 94 GHz millimeter-wavelength cloud radar,the back scattering and attenuation of non-spherical ice crystals with a variety of shapes are analyzed by DDA algorithm,moreover,the relationship between radar reflectivity factor（ Ze）,attenuation coefficient（ k） and Ice Water Content（ W） is revealed. Results show that：（ 1） the effects of ice particles types on back scattering and attenuation of ice particles depend on their sizes.（ 2） In the actual ice clouds,treating the hexagonal or ellipsoidal ice crystals as the same volume spherical particles would underestimate its attenuation and back scattering,however,treating aggregations as the same spherical volume would overestimate the scattering and attenuation. The back scattering of bullet flower crystals,compared with the spherical volume,may decrease or increase,but the attenuation is certain to be smaller than the spherical particles.（ 3） Ice models have great effects on Ze-k,Ze-W relations. The relationships between attenuation coefficient and radar reflectivity factor are derived based on refined models for the ice hydrometeors in the case of same particle sizedistributions. The results help process Chinese W band cloud radars data.

关 键 词：94 GHz云雷达 非球形冰晶 散射特性 衰减系数 

分 类 号：P412.25[天文地球—大气科学及气象学]