摘要
从大气辐射传输理论入手,用频谱分析方法研究了气象卫星遥感图像上云雾的可见光和红外光光谱特征,阐述了雾在NOAA各通道的光谱响应特征及相关指标。根据云雾的不同顶部结构,分析了云雾反射可见光的非朗伯特性。根据瑞利(Rayleigh)准则,解释了低太阳高度角时可见光对云雾具有更强的识别作用,指出雾与云相比,具有更强的方向性反射特点,当卫星处于云雾层的镜面反射方向时,雾区具有更强的亮度,即反射率高于云区;反之,雾区则相对较暗,指出可见光在云雾识别方面具有重要作用。通过分析云雾层的不同红外光谱特点,给出了一些云雾识别与分类的指标,说明了通道组合方法对云雾识别的重要作用,为云雾分类提供了依据。通过时间动态的频谱分析,给出了判断大雾成熟期的光谱特征,对判定大雾的发展与消散具有重要意义。
Based on the atmospheric radiation transmission theory,VIS(visible light) and IR(infrared) spectral characteristics of clouds and fog in the meteorological satellite remote-sensing images are studied in terms of spectral analysis method, which describes the spectrum response features and related index in the each channel of NOAA. According to the different cloud and fog top structure,the non-lambert property of cloud/fog reflecting visible light are analyzed.Based on the Rayleigh criterion,it is explained that visible light possesses more abilities of identifying fog and cloud when sun's altitude is lower,indicating that fog has stronger directivity reflecting characteristics than cloud.When the satellite is placed in the mirror-reflecting-direction of cloud and fog,the brightness is stronger in fog area than in cloud area,otherwise darker.This shows that visible light has important role in identifying fog and cloud.By analyzing the different IR(infrared) spectral characteristics of cloud and fog layers,some indices of identifying cloud and fog and their classifications are given, showing that the channel combination method is of significance in identifying cloud and fog, and provides proofs for the classification of cloud and fog.By analyzing the time-variation spectrum of fog,the spectral characteristics of heavy fog in mature phase are obtained,which has vital meaning on judging the development and dissipation of heavy fog.
出处
《南京气象学院学报》
CSCD
北大核心
2004年第3期289-301,共13页
Journal of Nanjing Institute of Meteorology
基金
总装型号项目(装技字1220号)
江苏省科技厅项目(BS2002066)
关键词
雾
气象卫星遥感
光谱特征
fog
meteorological satellite remote-sensing
spectral characteristic
