利用短波红外进行地基CO_2反演的影响因子分析  

Factors Analysis for CO_2 Retrieval from the Ground-Based Hyperspectral Measurements in the Short Wave Infrared

作　　者：霍彦峰[1,2] 段民征[2] 蒋哲[2] 梅林[3] 江崟[3] 毛夏 

机构地区：[1]半干旱气候变化教育部重点实验室兰州大学大气科学学院,甘肃兰州730000 [2]中国科学院大气物理研究所中层大气与全球环境探测重点实验室,北京100029 [3]深圳市国家气候观象台,广东深圳518040 [4]深圳市气象局,广东深圳518040

出　　处：《光谱学与光谱分析》2015年第9期2500-2504,共5页Spectroscopy and Spectral Analysis

基　　金：中国科学院战略性先导科技专项项目(XDA05040300);国家(863计划)项目(2011AA12A104-1)资助

摘　　要：地基CO2反演的精度决定了对CO2源和汇的认识程度,然而关于地基CO2反演影响因子的研究甚少。基于正演辐射传输模式,分析了气溶胶、光谱偏移、波段选取及光谱响应函数(类型、半宽和截断误差)对地基CO2反演的影响,旨在提高地基CO2反演的精度。结果表明:(1)当镜头视场角小于1.5°,且气溶胶光学厚度(λ=1.6μm)小于0.5时,气溶胶多次散射的贡献可以完全忽略;(2)光谱的偏移会造成反演结果偏小,反演误差随光谱偏移量非线性增大,且光谱的分辨率越高,光谱偏移的影响越大;(3)不同波段的平均信噪比不同,选择信噪比适中的通道和增强仪器信噪比可以减小噪声对地基CO2反演的影响;(4)光谱分辨率越高,模拟光谱对仪器光谱响应函数的准确度要求越高,高光谱观测时,必须保持环境温度的恒定才能获取高精度的反演结果;(5)光谱分辨率过高时,模拟光谱因串扰作用而失真,提高光谱仪分辨率的同时必须考虑串扰作用的影响。Ground-based CO2 inversion accuracy determines the understanding of CO2 source and sink.However the study about factors affecting ground-based CO2 inversion.In order to improve CO2 inversion accuracy,the effects from aerosol,spectral shift,spectral band selection,spectrometer response function type,half width and truncation error have been analyzed by using radiative transfer model.The results show that：（1）the multiple scattering of aerosol can be ignored when instrument field of view is less than 1.5°and aerosol optical depth is less than 0.5.（2）The inversion results are smaller when there are spectral off-sets.The inversion errors increase nonlinear with spectral offsets.And the higher the spectral resolution,the larger the effect of spectral shift.（3）Different spectral bands have various average signal-to-noise ratio,selecting channels with appropriate signal-to-noise ratio and enhancing instrument signal-to-noise ratio can reduce the effect of instrument noise.（4）The higher the instru-ment resolution,the more important the degree of accuracy of instrument line function for simulated spectrum.Therefore,for hyper-spectral observation,the constancy of environmental temperature is key of acquiring high precision inversion results.（5） For over-high spectral resolution,simulated spectrum is anamorphic due to crosstalk effect.Therefore the crosstalk effect must be considered when the spectrometer resolution is advanced.

关 键 词：气溶胶 光谱偏移 仪器响应函数 CO2反演 

分 类 号：P412.27[天文地球—大气科学及气象学]