Expected retrieval accuracies of bidirectional reflectance and albedo from EOS-MODIS and MISR angular sampling
Expected retrieval accuracies of bidirectional reflectance and albedo from EOS-MODIS and MISR angular sampling
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DOI：
10.1029/98jd00089
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发表时间：
1998-04
影响因子：
--
通讯作者：
W. Lucht
中科院分区：
文献类型：
--
作者：
W. Lucht
本文报告了预期的精度的双向反射率和反射率检索的角度采样提供的美国宇航局即将推出的中分辨率成像光谱仪（MODIS）和多角度成像光谱仪（MISR）的EOS-AM-1卫星平台。采用Myneni的离散坐标法辐射传输数值模型，模拟了6种不同双向反射分布函数（BRDF）类型（土地覆盖类型）在红色和近红外波段的双向反射率随纬度和时间的变化。这些模拟观测，然后使用三种不同的简单的BRDF模型计划用于未来的业务中的MODIS和MISR BRDF/反照率产品：互惠Ambrals，修改后的Rahman-Pinty-Verstraete（RPV），和修改后的Walthall BRDF模型。双向反射率和反射率反演研究不仅在平均太阳天顶角的观测，但外推到任意其他太阳天顶角以及。还研究了观测损失对云的影响。结果表明，可检索的2%至8%的中位数精度使用Ambrals或修改后的RPV模型的任何太阳天顶角的任何MODIS/MISR采样和预测的最低点视图反射率的精度也大多是在10%的误差范围内。对于所使用的Myneni正演模型，Ambrals模型可能稍微更准确。经验修正的Walthall模型的表现明显不如两个半经验模型。误差分布直方图允许评估的总体精度，预计从计划中的MODIS BRDF/反照率产品。
This paper reports expected accuracies of bidirectional reflectance and albedo retrievals from the angular sampling provided by NASA's upcoming moderate resolution imaging spectroradiometer (MODIS) and multiangle imaging spectroradiometer (MISR) on the EOS-AM-1 satellite platform. A numerical discrete ordinates method radiative transfer model by Myneni is used to simulate bidirectional reflectances for combined MODIS and MISR angular sampling as a function of latitude and time of year for six different bidirectional reflectance distribution function (BRDF) types (land cover types) in the red and near-infrared wave bands. These simulated observations are then inverted using three different simple BRDF models scheduled for use in the future operational MODIS and MISR BRDF/Albedo Products: the reciprocal Ambrals, the modified Rahman-Pinty-Verstraete (RPV), and the modified Walthall BRDF models. Bidirectional reflectance and albedo retrievals are studied not only at the mean solar zenith angle of observation but extrapolated to arbitrary other Sun zenith angles as well. The influence of loss of observations to clouds is also examined. Results show that albedo may be retrieved with 2 to 8% median accuracy using either the Ambrals or the modified RPV model for any solar zenith angle for any MODIS/MISR sampling and that the accuracy of predicted nadir view reflectance is also mostly within a 10% error margin. For the Myneni forward model used, the Ambrals model may be slightly more accurate. The empirical modified Walthall model clearly performs worse than the two semiempirical models. Error distribution histograms allow assessing the overall accuracy to be expected from the planned MODIS BRDF/Albedo Product.