VIIRS中波红外地表双向反射率反演算法研究

Study on mid-infrared land surface bidirectional reflectivity inversion algorithm of VIIRS

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。本文通过类似劈窗技术的计算模型计算出无太阳辐射时地表亮温T_g^0,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0°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。

The mid-infrared（ MIR） spectral region（ 3 ？5 jjim） is of an increasing interest in current earth observa-tions, and has many advantages compared to the visible regions. However,for the received radiation energy of satellite sensor at the daytime, there is energy coupling of reflected radiance and emitted radiance, which makes it a difficult task to take advantage of the MIR data. The ground brightness temperature 7^ without solar radiation was calculated based on a calculation model like the split-window technique. And then the inversion model for MIR land surface bidi-rectional reflectivity of VIIRS was derived based on MIR radiation transfer model. The results show that theoretical in-version value of reflectivity is consistent of actual value, RMSE is only 0. 009 at the solar zenith angle of 0°. Because the inversion model is little affected by meteorological factor and instrument noise,these influences can be neglected in practical applications.