FY-2D红外探测器窗区通道非线性特性及其定标订正方案

利用实验室定标与基于高光谱探测器IASI的交叉匹配样本，分析了FY-2D红外探测器在窗区通道的非线性特征，结果显示，VISSR在信号两端都存在非线性特征，但对低信号端的影响最为显著.与实验室测量结果比较，线性定标在低温端会带来大于10 K的亮温偏差.为了同时保证定标结果的质量及其稳定性，采用分段定标方案，高温端为线性定标而中低温端为非线性.从一致性以及台风个例分析等方面对定标方案进行了验证，分析结果表明，分段定标方案稳定，对低温端的定标精度改进显著，与线性结果比较台风监测亮温精度提升大于7K.

Nonlinearity of FY-2D infrared detector in thermal window channels and its correction method

FY-2 Visible and Infrared Spin Scan Radiometer had obviously nonlinear characteristics at low signal. It brought significant biases when using linear calibration in low temperature targets monitoring especially for typhoon targets, which seriously influences FY-2 quantitative application. Nonlinearity of FY-2D infrared detector in window channels was investigated using laboratory calibration measurements and collocation samples based on high-spectral sensor IASI. It was found that nonlinear performance existed both at high and low signal, but impacts at low signal were the most significant. Comparing with laboratory measurements, linear calibration could cause more than 10 K deviations at low temperature. In order to guarantee the quality of calibration results and its stability, nonlinear calibration scheme was applied only in low temperature area. Nonlinear calibration scheme was investigated from its consistency, and also typhoon application. The results indicated nonlinear calibration was stable, and significantly improved calibration accuracy at low temperature, especially in typhoon monitoring which was advanced at least by 7K.