Aircraft measurements of spectral surface albedo and its consistency with ground-based and space-borne observations
Aircraft measurements of spectral surface albedo and its consistency with ground-based and space-borne observations
复制标题
DOI：
10.1029/2008jd010089
复制
发表时间：
2008-09-11
影响因子：
4.4
通讯作者：
Schaaf, Crystal C.
中科院分区：
文献类型：
--
作者：
Coddington, Odele;Schmidt, K. Sebastian;Schaaf, Crystal C.
光谱表面散射，气溶胶遥感，表面气溶胶强迫和辐射传输计算需要准确知道的边界条件，也强烈影响地球的辐射平衡。从空间和飞机观测资料中获得地面大气修正的困难主要在于大气修正，特别是在气溶胶密集区。由于尺度不同，将卫星检索与机载或地面观测进行比较并不简单。我们使用太阳光谱通量辐射计（SSFR）测量Megacity Initiative期间飞机高度的向上和向下辐照度：当地和全球研究观测（MILAGRO），以确定地面站和沿着飞行轨迹的光谱表面反射率（在350至2100 nm的波长范围内），从而将飞行水平的反演测量结果与墨西哥城污染环境中的大规模卫星观测结果联系起来。我们的方法涉及迭代调整的SSFR特定的辐射传输模型的表面辐射输入，直到建模向上的辐照度匹配的SSFR测量在飞行水平。一个敏感性分析的表面散射气溶胶光学特性提供了一个检索的不确定性，这可以超过SSFR仪器的不确定性在高度可变的条件下（或不确定的测量）的气溶胶光学厚度和不对称参数。来自SSFR、多滤光片旋转阴影波段辐射计和NASA-EOS Terra和Aqua卫星上的中分辨率成像光谱仪（MODIS）仪器的光谱表面反射率之间的比较分别显示为6-10%和0.025-0.05个单位的差异。SSFR和MODIS之间的沿轨比较表明，两种仪器（飞机和卫星）可以捕捉到不均匀的表面反射景象的变化。
Spectral surface albedo, a boundary condition which needs to be accurately known for aerosol remote sensing, surface aerosol forcing, and radiative transfer calculations, also strongly affects Earth's radiation balance. The difficulty in deriving surface albedo from space and aircraft observations lies mainly in the atmospheric correction, especially in aerosol-burdened regions. Because of the different scales, comparing satellite retrievals with airborne or ground-based observations is not straightforward. We use Solar Spectral Flux Radiometer (SSFR) measurements of upward and downward irradiance from aircraft altitude during Megacity Initiative: Local and Global Research Observations (MILAGRO) to determine spectral surface albedo at ground stations and along the flight track (over the wavelength range 350 to 2100 nm), thereby linking flight-level retrieved measurements to larger-scale satellite observations in the polluted Mexico City environment. Our approach involves iteratively adjusting the surface albedo input of a SSFR specific radiative transfer model until the modeled upward irradiance matches the SSFR measurements at flight level. A sensitivity analysis of surface albedo to aerosol optical properties provides a retrieval uncertainty, which can outweigh the SSFR instrument uncertainty under highly variable conditions (or uncertain measurements) of aerosol optical depth and asymmetry parameter. Comparisons between spectral surface albedo derived from the SSFR, Multi-Filter Rotating Shadowband Radiometer, and the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument onboard the NASA-EOS Terra and Aqua satellites are shown with differences of 6-10% and 0.025-0.05 units, respectively. Along-track comparisons between the SSFR and MODIS show that two instruments (aircraft and satellite) can capture inhomogeneous surface albedo scene changes.