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首页> 外文会议>Conference on Optics in Atmospheric Propagation and Adaptive Systems Ⅳ Sep 18-20, 2001, Toulouse, France >Vicarious calibration and validation in the thermal region
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Vicarious calibration and validation in the thermal region

机译：在热区域进行替代性校准和验证

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A vicarious calibration was performed for the thermal channels of the airborne DAIS imaging spectrometer during ESA campaigns in Barrax (Spain) in 1998, 1999 and 2000. Ground measurements of temperature were collected in different fields coincidentally with the flights to provide calibration and validation targets for the thermal channels of DAIS. Two calibration targets were selected (water and bare soil) to cover the range of expected surface temperatures in the area. Targets were very homogeneous thus facilitating the acquisition of ground measurements comparable to the remote measurements of DAIS. The derived two-point, linear calibration equations operate on at-sensor radiances and are used to obtain calibrated DAIS data from the original data. Calibrated at-sensor radiances were validated using ground measurements for several fields (other than those used for the calibration). For the present study the validation was made for the two flight lines of June 3, 1999. The comparison of DAIS-derived and ground-measured values was made in terms of both the surface temperature and emissivity. For the processing of the DAIS data, an adjusted normalised emissivity method was used where the input emissivities were selected for each surface according to the field measurements. With this procedure we could derive the six channel emissivities plus the surface temperature for each target. The accuracy of these estimates depends on the selected input emissivity and notably on the atmospheric correction of the DAIS thermal channels. For the Barrax site, the atmospheric correction was calculated with local radiosonde measurements and the MODTRAN 4 code. The results of the validation indicate that surface temperatures and channel emissivities could agree with ground measurements within +-1 ℃and +-0.01 respectively.
机译：在1998年，1999年和2000年在西班牙Barrax的ESA活动期间，对机载DAIS成像光谱仪的热通道进行了替代性校准。与飞行同时进行的是，在不同的领域收集了地面温度测量值，以提供校准和验证目标DAIS的热通道。选择了两个校准目标（水和裸土）以覆盖该区域预期的地表温度范围。目标非常均匀，因此有助于获得与DAIS的远程测量相当的地面测量。导出的两点线性校准方程式在传感器辐射下运行，用于从原始数据中获得校准的DAIS数据。使用多个场的地面测量值（除了用于校准的场外）对校准的传感器辐射亮度进行了验证。在本研究中，对1999年6月3日的两条飞行路线进行了验证。根据表面温度和发射率，对DAIS得出的值和地面测量值进行了比较。对于DAIS数据的处理，使用调整后的归一化发射率方法，其中根据现场测量为每个表面选择输入发射率。通过此程序，我们可以得出每个目标的六个通道发射率加上表面温度。这些估计的准确性取决于所选的输入发射率，尤其取决于DAIS热通道的大气校正。对于Barrax站点，使用当地无线电探空仪测量和MODTRAN 4代码计算大气校正。验证结果表明，表面温度和通道发射率分别与地面温度在+ -1℃和+ -0.01范围内一致。

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