The surface reflectance is one of the most critical parameters during a field vicarious calibration. Traditional methods to measure the surface reflectance require personnel at the test site. A ground-viewing radiometer is built to measure the surface reflectance automatically. The radiometer has eight channels in the wavelength range from 400 nm to 1550 nm. The optical system is temperature controlled. A feedback resistor calculation method is introduced that is used to obtain a reasonable signal. Solar radiation-based calibration and two other laboratory methods are used to obtain the absolute calibration coefficients of the radiometer. The average difference in top-of atmosphere spectral radiance is less than 5% between the nine bands of S-NPP and automated vicarious calibration for eight months. The difference of apparent radiance between the results of OLI and automated vicarious calibration is mostly within 5%, therefore, the radiometer works effectively.

中文翻译：

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用于自动替代校准的地面观测辐射计的设计原理和辐射校准

表面反射率是场替代校准过程中最关键的参数之一。测量表面反射率的传统方法需要人员在测试现场。地面观测辐射计用于自动测量表面反射率。辐射计有 8 个通道，波长范围从 400 nm 到 1550 nm。光学系统是温度控制的。介绍了一种反馈电阻计算方法，用于获得合理的信号。基于太阳辐射的校准和其他两种实验室方法用于获得辐射计的绝对校准系数。八个月的 S-NPP 和自动替代校准的 9 个波段之间的大气顶部光谱辐射平均差异小于 5%。