光学学报, 2018, 38 (1): 0128004, 网络出版: 2018-08-31   

空间辐射基准传递不确定性的光谱敏感性分析 下载: 770次

Sensitivity of Intercalibration Uncertainty on Spectral Sampling of Space-Based Radiance Standard
作者单位
1 南京信息工程大学环境科学与工程学院, 江苏 南京 210044
2 中国气象局国家卫星气象中心, 北京 100081
3 中国气象局中国遥感卫星辐射测量和定标重点开放实验室, 北京 100081
4 中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室, 北京 100029
摘要
空间辐射基准对卫星观测气候变化的研究具有重要意义,空间辐射基准的建立不仅可以提高卫星自身观测的相对精度,而且还能通过基准传递来满足其他卫星的在轨溯源需求,用于基准传递的空间高光谱基准遥感器的光谱分辨率对传递相对精度有重要影响。分别利用MODTRAN模式和AER LBL模式的模拟结果作为高光谱遥感器的太阳反射波段和地球热发射波段的代理数据,分析了光谱采样对光谱辐射观测结果的影响以及光谱采样差异引起的辐射基准传递的不确定性。考虑5种下垫面和6种大气条件,对比了不同光谱采样间隔下光谱辐射的差异,并利用敏感性实验的方法,以MERSI-II为目标遥感器,评估了空间辐射基准交叉传递的光谱不确定性。结果表明:光谱采样间隔越大,光谱辐射的差异越大,在气体吸收区、绝对辐射低信号区、近紫外太阳光谱暗线区的最大辐射差异可达100%;在大气窗区,当太阳反射波段的光谱采样间隔优于4 nm时,基准传递的不确定性小于0.3%,当地球热发射波段光谱的采样间隔优于2 cm -1时,不确定性可小于0.1 K;在近紫外太阳光谱暗线区和气体吸收区,太阳反射波段的基准传递对光谱采样十分敏感,当采样间隔为4 nm时,中心波长为1.38 μm的通道的不确定性可达40%,当地球热发射波段在7.2 μm水汽弱吸收区时,光谱采样间隔优于0.8 cm -1才能满足不确定性小于0.1 K的需求。
Abstract
The space-based radiance standard is of great significance for the study of the satellite observing climate change. The establishment of the space-based radiance standard can not only improve the relative accuracy of satellite observations, but also meet the traceable needs of other satellites through intercalibration. The spectral resolution of the hyperspectral standard remote sensor in space for intercalibration has a significant effect on the intercalibration relative accuracy. The simulations of spectral radiances by modes of MODTRAN and AER LBL are used as proxy data of the hyperspectral remote sensor in reflective solar bands and thermal emissive bands, respectively. The influence of spectral sampling on the observation of spectral radiation and the uncertainty of the radiation standard intercalibration caused by the spectral sampling are analyzed. Considering five kinds of underlying surfaces and six kinds of atmospheric conditions, the difference of spectral radiation under different spectral sampling frequencies is compared, and the spectral uncertainty of the space-based radiance standard intercalibration is evaluated with the utilization of the sensitivity experiment method with MERSI-II as the target remote sensor. The results show that the larger the spectral sampling frequency, the greater the difference in spectral radiation. The maximum radiation difference is up to 100% in atmospheric absorption spectra, low signal spectra, and near ultraviolet solar dark-line spectra. In the atmospheric window, the spectral sampling frequency better than 4 nm can produce radiance to meet the on-obit intercalibration standard with an uncertainty less than 0.3% in reflective solar bands, and the spectral sampling frequency better than 2 cm -1 can also produce radiance temperature to meet the on-obit intercalibration standard with an uncertainty less than 0.1 K in thermal emissive bands. In the near ultraviolet solar dark-line spectra and the atmospheric absorption region, the intercalibration of reflective solar bands is very sensitive to the spectral sampling. The uncertainty of intercalibration is up to 40% at a sampling frequency of 4 nm in the channel with a central wavelength of 1.38 μm. The spectral sampling of 0.8 cm -1 can produce radiance temperature to meet the on-obit intercalibration standard with an accuracy of 0.1 K in the weak atmospheric absorption channel with a central wavelength of 7.2 μm in thermal emissive bands.

陈申玮, 徐娜, 戴铁, 周心易, 吕浩, 程越茗. 空间辐射基准传递不确定性的光谱敏感性分析[J]. 光学学报, 2018, 38(1): 0128004. Shenwei Chen, Na Xu, Tie Dai, Xinyi Zhou, Hao Lü, Yueming Cheng. Sensitivity of Intercalibration Uncertainty on Spectral Sampling of Space-Based Radiance Standard[J]. Acta Optica Sinica, 2018, 38(1): 0128004.

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