Comparison between Microwave Coherent and Incoherent Scattering Models in Corn Field

[Objective] The aim was to compare and analyze microwave coherent and incoherent scattering models in a corn field. [Method] In the research, based on a coherent scattering model （Stile）, we proposed a coherent scattering model exclusive for corn, in which, physical optics （PO） and infinite-length dielectric cylinder were used to calculate single-scattering matrices of corn leaves and stalks. In addition, coherent components produced from interaction among the scattering mechanisms were also considered and this coherent model was compared with the Michigan Mi- crowave Canopy Scattering （MIMICS） model. The measured data in a corn filed in Gongzhuling in Jilin Province were used as the input parameters of the coherent and incoherent models. We simulated backscattering coefficients of VV and HH po- larization at L and C bands and made a comparison between the simulation results. [Result] The simulation results at L-band were poor, which indicated that we could not find regularity at early growth stage of vegetation. In addition, comparisons be- tween coherent and incoherent scattering models proved that the coherence triggered by the scattering mechanism was small. [Conclusion] In the research, we analyzed differences between coherent and incoherent scattering models with change of incident angle, and further analysis on the differences with change of vegetation and soil needed to be made in future.

卫星和地基遥感观测资料约束下的核-壳态气溶胶光学特性模拟研究

针对结合星地观测与模型定量模拟消光性气溶胶光学特性及黑碳质量空间分布这一热点问题,利用TROPOMI卫星紫外波段观测数据与AERONET地基观测数据,基于“核-壳”假设下的米散射模型提出了一种准确量化黑碳气溶胶质量空间分布的模拟方法,并对北京、中国香港、首尔三个站点的模拟结果进行分析与验证。多源数据约束后米散射模型模拟得到的结果显示:北京的吸收系数在0.04~0.13之间,中国香港的吸收系数整体小于0.08,首尔的吸收系数介于0.02~0.06之间。计算得到的黑碳气溶胶柱内质量空间分布结果显示:北京站黑碳气溶胶柱内质量在200~600 kg/grid之间,中国香港站黑碳气溶胶柱内质量在180~650 kg/grid之间,首尔站黑碳气溶胶柱内质量在300 kg/grid以下。结合卡尔曼滤波排放清单与一阶箱模型对黑碳气溶胶柱内质量结果进行间接验证,计算得到的黑碳气溶胶生命周期为1~4 d不等,符合其在大气中的真实状态,说明结果具有一定可靠性。通过对比加入TROPOMI紫外波段卫星观测数据前后对模型进行约束得到的粒径分布及吸收系数结果的差异发现:加入紫外波段观测数据对模拟结果具有一定增强作用。所提方法模拟结果良好,方案具有一定应用潜力。

观测约束下的煤矿区吸光气溶胶特性模拟研究

利用黑碳仪、光学粒度仪和太阳光度计在山西省长治市煤矿区开展连续实地观测,结合“核-壳”假设下的米散射模型,对煤矿区吸光气溶胶光学特性进行建模,提出一种基于多源地基观测快速反演吸光气溶胶单次散射反照率(SSA)的方法,并通过使用吸收Angstrom指数对模拟结果进行约束,分析了不同混合状态下吸光气溶胶光学特性的变化规律。结果表明:1)煤矿区吸光气溶胶粒径分布与污染条件相关,重度污染条件下粒径较大,中度污染条件下粒径较小,其中不同污染条件均在0.28~0.3μm等较小粒径区间内存在峰值,这表明排放源对粒径分布有重要影响;2)基于“核-壳”假设的米散射模型可以模拟不同混合状态下吸光气溶胶的SSA,以440 nm粒径为例,在均匀假设下SSA为0.43~0.72,在非均匀假设下SSA为0.41~0.65,这表明使用多波段、多粒径信息可以更准确地获取吸光气溶胶光学特性;3)吸收Angstrom指数只能在部分粒径区间与SSA相匹配,且无法应用至较大粒径区间,表明通过吸收Angstrom指数评估吸光气溶胶SSA的方法会产生偏差,应综合考虑粒径分布、混合状态和波长对其产生的影响。