CAJ | 학술논문

清沽水体光谱在可见光和近红外波段的反射率比较低,其光谱特征不明显,在光学遥感图像上水体一般都表现为暗色调,造成了利用光谱学手段进行水体遥感识别和水质参数反演的困难.在研究水体的偏振波谱时作者发现,在对水体进行多角度观测时,水体在可见光与近红外波段的偏振度波谱值要远大于其无偏的反射率,表现在图像上即水体的偏振度图像的亮度要远大于其强度图像的亮度,文章对这种现象和规律进行了物理学解释,并利用法国PARASOL多角度偏振卫星遥感图像数据对这个规律进行了验证.该文首次揭示了利用多角度偏振遥感进行水体探测的优势,该方法有效解决了在利用光学遥感进行水体探测时反射率低的难题,大大提高水体的遥感识别能力和水质参数反演精度.
청고수체광보재가견광화근홍외파단적반사솔비교저,기광보특정불명현,재광학요감도상상수체일반도표현위암색조,조성료이용광보학수단진행수체요감식별화수질삼수반연적곤난.재연구수체적편진파보시작자발현,재대수체진행다각도관측시,수체재가견광여근홍외파단적편진도파보치요원대우기무편적반사솔,표현재도상상즉수체적편진도도상적량도요원대우기강도도상적량도,문장대저충현상화규률진행료물이학해석,병이용법국PARASOL다각도편진위성요감도상수거대저개규률진행료험증.해문수차게시료이용다각도편진요감진행수체탐측적우세,해방법유효해결료재이용광학요감진행수체탐측시반사솔저적난제,대대제고수체적요감식별능력화수질삼수반연정도.
The reflectance of pure water is very low at visible and near infrared bands.Its spectral characteristics are not obvious.Water always shows dark hue in optical remote sensing images.This dark hue causes the difficulties in water remote sensing identification.There is an interesting phenomenon when the authors research the water polarization spectroscopy.The authors measured water's polarization spectra and reflectance spectra at different view zenith angles using the ASD spectrometer.When the view zenith angle was zero(measured vertically),as the spectrum people commonly measure,there was no polarization phenomenon at the water surface,and the reflectance was low at each band.Along with the increase in view zenith angle,the DOP spectra curves increased evidently,while the reflectance curves only changed a little When the view zenith angle was over 30 degree,the values of DOP spectrum were much larger than the reflectance spectrum values at the entire visible and near infrared bands.At some bands,the DOP value was several dozen times than its reflectance value.This phenomenon shows that the water's brightness in DOP image is much higher than its brightness in intensity image under the same condition.This rule was verified by the PARASOL multiangle polarization satellite data.Comparing the average brightness of DOP images with the average brightness of intensity images at 490,670 and 865 nm band,the former is higher than the latter apparently.The brighter DOP images are better for water remote sensing identification.It is the first time that the authors found this special muhiangle polarization spectral character of water.It revealed the advantage of water detection using the muhiangle polarization remote sensing data.This method solved the low reflectivity problem of water color remote sensing.It will greatly improve the capability of water remote sensing identification and the retrieval accuracy of water quality parameters.