摘要
为保障大气痕量气体差分吸收光谱仪(EMI)二级反演数据的有效性和可靠性,需长期监测仪器在轨辐射定标准确性和稳定性。首先,根据EMI在轨测量的太阳光谱和星下点辐亮度,计算了南极洲和格陵兰岛永久冰雪地面选定数据区域的表观反射率时间序列,并建立了太阳天顶角和表观反射率的4阶双向反射分布函数(BRDF)模型。然后,利用4阶BRDF模型对2018~2020年的表观反射率数据序列进行归一化处理,得到了表征EMI定标准确性和稳定性的指标。结果表明,基于BRDF模型得到的表观反射率预测值与实测值相关系数高于0.9;用BRDF模型对表观反射率进行归一化处理后,得到的仪器辐射定标不确定度范围为2%~5%;UV2、VIS1通道两年总衰减的范围为-0.5%~0.5%,VIS2通道的两年总衰减约为1.9%,即EMI在轨运行两年间的辐射响应稳定性较高。
To ensure the validity and reliability of the secondary inversion data of environmental trace gases monitoring instrument(EMI),it is necessary to monitor the radiometric calibration accuracy and stability of the instrument in orbit for a long time.First,according to the solar spectrum and sub star radiance data measured by EMI in orbit,the surface reflectance time series of the selected data area of permanent ice and snow surface in Antarctica and Greenland are calculated,and the fourth-order bidirectional reflectance distribution function(BRDF)model between the solar zenith angle and the surface reflectance is established.Then,the surface reflectance data series from 2018 to 2020 are normalized by the fourth-order BRDF model,and the indicators representing the calibration accuracy and stability of EMI are obtained.The results show that the correlation coefficient between the predicted value of surface reflectance obtained by BRDF model and the measured value is better than 0.9.After normalizing the surface reflectance with the BRDF model,the uncertainty of radiometric calibration ranges from 2%to 5%.The total attenuation of UV2 and VIS1 channels range from-5%to 5%in two years,and that of VIS2 channel is about 1.9%,which indicates that the radiation response of EMI is stable during two years of operation in orbit.
作者
苏静明
司福祺
赵敏杰
周海金
洪炎
Su Jingming;Si Fuqi;Zhao Minjie;Zhou Haijin;Hong Yan(Key Laboratory of Environmental Optical and Technology,Anhui Institute of Optics and Fine Mechanics,Hefei Institutes of Physical Sciences,Chinese Academy of Sciences,Hefei,Anhui 230031,China;University of Science and Technology of China,Hefei,Anhui 230026,China;College of Electrical and Information engineering,Anhui University of Science and Technology,Huainan,Anhui 232001,China)
出处
《光学学报》
EI
CAS
CSCD
北大核心
2022年第6期71-78,共8页
Acta Optica Sinica
基金
安徽省自然科学基金(1808085QD114)。
关键词
大气光学
大气痕量气体差分吸收光谱仪
大气表观反射率
双向反射函数分布模型
辐射定标精度
辐射定标稳定性
atmospheric optics environmental trace gases monitoring instrument
top of atmosphere reflectance
bidirectional reflectance distribution function model
radiometric calibration accuracy
radiometric calibration stability
