海洋水色CCD成像仪光谱非线性校正

个理想的光学遥感器，在响应波段内光谱响应度是完全平直的，遥感器的输出与入射的辐射成完全的线性关系；而实际的遥感器并非如此，它的光谱响应度在响应波段内并不是平直的，这就使遥感器的输出不仅与入射的辐射有关，还与遥感器的光谱响应度有关，实际测量时，由于目标光谱形状的差异会导致输入与输出之间的非线性关系。利用仪器定标时采用的光源光谱形状与实际测量时目标光谱形状对仪器的输出数据进行校正会有效地减小由于遥感器的光谱响应非均匀性引入的测量误差。文中利用测得的海洋水色ＣＣＤ成像仪的各波段光谱响应度，计算了已归一化为具有相同的带内平均光谱辐亮度的不同温度黑体输出，由输出结果可以看到，不同的光谱形状对海洋水色ＣＣＤ成像仪的输出影响较大，为了减小由此引入的测量误差，文中对实验室定标用积分球光源和海洋水色ＣＣＤ成像仪在轨工作时的典型输入辐亮度的光谱特性进行了等效黑体拟合，并以此为依据计算了海洋水色ＣＣＤ成像仪在轨工作时的光谱非线性修正因子。

Spectral Nonlinearity Correction for Ocean Color CCD Imager

For an ideal multi spectral remote sensor, there is a completely linear relat ionship between the output of the sensor and the incident radiation due to the even in band spectral response; but for an actual sensor, the output of the sen sor not only depends on the incident radiation, but also on the spectral respon se of the sensor, this will result in the nonlinearity between the output of th e sensor and the incident radiation. Correcting the output data of the sensor b y the use of the spectral shapes of the calibration source and the measured objec t will effectively reduce the measuring error due to the nonlinear response of t he sensor. We have adopted the measured spectral response of Ocean Color CCD Imager (OCCI), and calculated the response of OCCI to blackbodies at different temperatures which have been normalized to have the same in band average spectr al radiance. It can be seen from the calculated results that the spectral shap es have great influence on the output of OCCI. To reduce the measuring error due t o the nonlinear response, the nonlinear correction factor has been computed acco r ding to the spectral shape of the integrating sphere and the on orbit spectral shape for OCCI ocean measurement, which can fit a 12000 K blackbody.