VIIRS 中波红外地表双向反射率反演算法研究
首发时间:2017-05-11
摘要:中波红外(mid-infrared, MIR)是目前地球观测中热点研究的光谱区域,相比于可见光和热红外波段具有很多优势。中波红外反射率在叶生物量估算、不同植被类型区分等方面得到了广泛的应用。但由于在白天时卫星传感器接收到的辐射能量存在反射与发射能量耦合的问题,使得中波红外数据的利用存在一些困难。本文通过采用类似劈窗技术的计算模型计算出无太阳辐射时地表亮温 ,并结合中波红外辐射传输模型推导出了适用于VIIRS中波红外地表双向反射率的反演模型。结果表明:反射率理论反演值与实际值较吻合,在太阳天顶角为 时RMSE仅为0.009;反演模型受气象因子和仪器噪声的影响很小,在实际应用中可以忽略。
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Study on Mid-infrared Land Surface Bidirectional Reflectivity Retrieval Algorithm of VIIRS
Abstract:The mid-infrared (MIR) spectral region (3-5 μm) is an increasing interest with respect to the current Earth observations, and has many advantages compared to the visible and thermal-infrared (TIR) regions. The reflectivity in MIR spectral region has been widely used in estimating leaf biomass and distinguishing different vegetation types and so on. However, observations at satellite altitude during the daytime consist of a combination of reflected radiance (due to sun irradiance) and emitted radiance (from both the surface and the atmosphere), which makes it a difficult task to take advantage of the MIR data. In this paper, the ground brightness temperature without the contribution of the solar direct beam that only related with the solar zenith angle could be estimated based on a calculation model as the split-window technique. And then the model to retrieve land surface bidirectional reflectivity( )from VIIRS was derived based on radiation transfer model in MIR The results showed that: the calculation model worked well and he RMSE of actual values of with our proposed method is determined to be 0.009 for the solar zenith angle at nadir. A detailed error analysis found less effects made by instrumental noise and meteorological factors on the retrieval of , which can be neglected in practical applications.
Keywords: mid-infrared land surface bidirectional reflectivity ground brightness temperature VIIRS
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No.4732556119990914****
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