Fig. 1. Multi-angle observation geometries adopted in the simulation, information content analysis and a posteriori error analysis. The solid circle, diamond, square and triangle with = 0° represent the corresponding position of the Sun for Geometry1−4, respectively. 研究采用的DPC多角度观测几何

Fig. 2. Illustrationsof observation scenarios with different number of viewing angles.不同观测角度个数的观测示意图

Fig. 3. Distribution of the range of scattering angle corresponding to the geometries in Fig. 1.四组观测在不同观测角度个数下的散射角分布

Fig. 4. Contribution of surface reflectance to TOA reflectance at 443, 490, 565, 670 and 865 nm, as well as the influence of BRDF parameter error to TOA reflectance for vegetation ((a)–(e)) and bare soil ((f)–(j)) surface. The horizontal axis of each case is arranged by scattering angle.不同观测几何下的地表反射率、表观反射率以及地表模型参数误差对表观反射率的影响 (a)–(e) 植被地表; (f)–(j) 裸土地表

Fig. 5. Contributionof polarized reflectance to TOA polarized reflectance for vegetation surface at 490, 670 and 865 nm, as well as the influence of BPDF parameter error to TOA polarized reflectance.不同观测几何下植被地表偏振反射率和表观偏振反射率, 以及10%的参数不确定性对二者的影响

Fig. 6. The total DFS of aerosol((a)−(d)) and surface((e)−(h)) parameters as functions of number of viewing angles in terms of surface type(vegetation and bare soil) and aerosol type (fine-dominated and coarse-dominated) with AOD_{550 nm} = 0.5. Quantities in each box-whisker include the median (dash in the box), the 25^th and 75^th percentiles (box), and the minimum and maximum (whiskers) for each number of viewing angles bin. 气溶胶和地表参数的总信息量随观测角度数量的变化情况 ((a)—(d)) 气溶胶参数; ((e)—(h))地表参数

Fig. 7. The DFS of aerosol and surface parameters under condition of 12 viewing angles (AOD_{550 nm} = 0.5): (a) Aerosol; (b) surface. Each histogram and error bar are the mean value and standard deviation of different geometries. 不同观测几何下气溶胶和地表各参数的信息量　(a)气溶胶; (b)地表

Fig. 8. The posteriori error of retrieved aerosol parameters (a) and surface parameters (b). The histogram and error bars are the mean and standard deviation of different geometries (Geometry 1−4). Both (a) and (b) are calculated under condition of 12 viewing angles (AOD_{550 nm} = 0.5). The gray histogram means the priori estimate error. 多角度观测下气溶胶和地表参数的后验误差(灰色底柱为先验估计误差)

Fig. 9. The posteriori error of retrieved aerosol and surface parameters as a function of number of viewing angles (AOD_{550 nm} = 0.5). The curve and the error bar are the mean value and standard deviation of different aerosol and surface type, respectively. 地表和气溶胶参数的后验误差随观测角度数量的变化情况

Fig. 10. The posteriori error of retrieved aerosol and surface parameters as a function of measurement error (AOD_{550 nm} = 0.5). The solid line and the error bar are the mean value and standard deviation of different aerosol and surface type, respectively. The dash line denotes the contribution from polarized observation error. 地表和气溶胶参数的后验误差随观测误差的变化情况

Fig. 11. The a posteriori error of retrieved aerosol and surface parameters as a function of aerosol model error (AOD_{550 nm} = 0.5). The curve and the error bar are the mean value and standard deviation of different aerosol and surface type, respectively. 地表和气溶胶参数的后验误差随气溶胶模型误差的变化情况

Table 1. Basic characteristics of DPC sensor.