【作者】 孙仲秋；

【导师】 赵云升；

【作者基本信息】 东北师范大学 ， 地图学与地理信息系统， 2013， 博士

【摘要】 积雪是地球表面最为活跃的地物类型之一，而且积雪一些特征的改变能反映出环境的变化。积雪反照率同时也是气候研究与积雪范围确定所需要重要的量化指标。因此，积雪的监测对全球气候变化研究以及水资源管理与预测研究具有重要的意义。对高山地区、极地地区和不易通行区域的积雪进行监测的一个有效的方法是利用遥感技术获取的信息来反演积雪表面的特征参数。遥感技术应用在积雪监测上主要是利用传感器获得的积雪表面的反射与辐射信息，分析出对应的积雪特征参数。遥感技术可以根据不同时间序列与空间尺度的信息来反演出积雪的特征信息，这也为不同尺度的气候模型与水文模型提供了必要而精确的输入参数。被动遥感技术当中，积雪在反射与辐射过程中会由于自身性质改变而使传感器获得对应的特征信息发生变化，遥感技术也正是利用这些变化来区分积雪表的不同特征。而在积雪表面与电磁波相互作用的过程当中，偏振现象往往被忽视。积雪表面的反射信息中包含着丰富的偏振信号，尤其是在极地与高山地区，太阳入射天顶角会变得较大，这就使得探测器在较大的探测天顶角方向获取的反射信息中包含更多的偏振信息。而伴随着大的入射天顶角和探测天顶角的出现，利用现有遥感模型反演积雪性质会引起较大的误差。因此，无论是为了更完整、详细的了解积雪表面与电磁波的辐射过程还是探索在较大入射天顶角和探测天顶角利用偏振信息反映积雪性质的可能，对积雪偏振特性的研究应该是积雪遥感中不可或缺的一部分。本文的研究重点主要围绕两个方面着重进行研究，首先研究过程中以辐射传输理论、斯托克斯参数与积雪表面反射和发射偏振特征之间的关系为理论基础，系统、全面的分析了积雪表偏振信息的方向特征和偏振光谱特性，即积雪在可见光近红外波段的反射特性与热红外波段的发射偏振特性；其次通过可见光近红外偏振反射信息反映出积雪的一些性质，试图建立积雪的偏振特性与积雪性质之间的关系。研究结果表明：在对积雪表反射信息全部偏振信息测量过程中发现，积雪表面反射信息中在可见光近红外波段范围内包含有较丰富的偏振信息，而且存在着明显的方向性特征。在前向散射方向反射光中的偏振信息最强烈，尤其是在入射主平面内；而后向散射方向出现了负偏振。积雪在热红外波段的发射辐射信息也存在偏振特性，但是主要与探测天顶角有关，而且各向异性特征随着探测方位角度的变化比较明显，同时在热红外波段的发射偏振也与波段有关。偏振度作为偏振信息与积雪特性参数之间关系研究过程中的指标，发现偏振度对积雪粒径是非常敏感的，尤其在可见光近红外波段，可以利用偏振度很好的区分出积雪粒径的大小；而在研究中含水湿积雪的偏振度会比干积雪的偏振度小；同样，除了以上两种积雪性质外，积雪中污染物的含量也影响积雪的偏振反射特性。总之，对积雪的偏振特性的研究以可以完整的了解积雪与电磁波之间的相互作用；偏振特性与积雪性质关系的探索也为遥感技术中利用偏振信息获得新的有科学依据的认识提供理论与方法上的支持。本研究中将角度信息、偏振信息与积雪性质信息结合在一起，不仅分析了由于角度变化对偏振信息影响，偏振反射与双向反射之间的定量化关系，而且结合了积雪特性参数对偏振信息的影响。力求在对积雪偏振特性详细了解的基础上，利用偏振信息反映出积雪性质特征。这对于实现偏振遥感对积雪的监测具有理论与实践意义。同时也为遥感技术在积雪监测的理论基础研究开辟了新的思路和方向，使遥感方法获取的信息领域更广泛，从而可以获得更多反演积雪性质的遥感信息。更多还原

【Abstract】 The snow cover is one of the most active particulate surfaces on the Earth, andthe changes of snow property relates to the environment condition. Snow albedo isalso the indicators of climate research and snow cover. Therefore, monitoring thesnow is important for the application to global climate change and water resourcesmanagement and prediction. Remote sensing technology is a valid method forobtaining information to invert the characteristic parameters of snow surface fromalpine areas, polar region and hard access area. The applications of remote sensingtechnoloty in snow monitoring mainly take advantange of the snow surface reflectionand radiation using sensers, and analysising the snow parameters from theseinformation. Remote sensing technology can be anti-the performances snowcharacteristics according to the different time series and spatial scales, climate modelsand hydrological models for different scales, which also provides the necessary andaccurate input parameters.For passive remeote sensing, in which snow will be in the process of reflectionand radiation due to the change of itself, the sensor detects these information todistinguish the different characteristics of the snow table. Among the snow surfaceelectromagnetic wave interactions, polarization is ofter ignored The light reflected bythe snow surface contains rich polarized signals, especially in the polar and alpineregions. With Sun incident angles increasing, this makes the detector obtain morepolarized information and with incident zenith angle and detection zenith angle, theemergence of the use of the existing remote sensing model inversion of snowparameters causes large errors. Therefore, whether it is for a more complete anddetailed understanding of the snow surface with electromagnetic radiation process orexplore possible use of polarization information reflects the snow parameters in largeincident zenith angle and viewing zenith angle, the study of the polarization propertiesof snow should is an integral part of snow in remote sensing.In this study, we mainly focused on two aspects, a theoretical basis for therelationship between the processes of radiation transfer theory, the Stokes parameterswith the snow surface reflection and emission polarization characteristics, systematicand comprehensive analysis of the first study for the snow surface in the direction ofthe polarization information characteristics and polarization spectral characteristics.The reflective properties of snow in visible and near-infrared bands and emissionpolarization properties of the thermal infrared band; followed through the snow in thevisible and near infrared polarized reflectance information reflects the characteristic parameters, trying to establish between the polarization properties of snow and snowparameters relationship. The results show that:The reflected information of snow surface in the range of visible andnear-infrared wavelength range contains polarization information, and there is a cleardirectional characteristics found in the snow surface reflection for all the informationpolarization measurement process. The polarization information of the first reflectedlight to the scattering direction is most intense, especially in the principle plane; thenappears to the scattering direction of negative polarization Polarization properties ofsnow emitted radiation in the thermal infrared band information is also found, butmainly relate to viewing zenith angle, and anisotropic features is more obvious withthe viewing angle increasing. At the same time, the wavelength dependence isappeared for thermal polarization.The degree of polarization as an indicator in the course of the study of therelationship between the polarization information and snow parameters, we find thatthe degree of polarization of snow is sensitive to grain size, especially in the visibleand near-infrared band; we can take advantage of the degree of polarization todistinguish snow grain size The degree of polarization of wet snow is smaller than thedegree of dry old snow. Contaminants in the snow also affect the polarized property ofsnow.In short, the polarization properties of snow can be important for understandingthe interaction between snow surface and electromagnetic waves; the exploration ofthe polarization properties of snow parameters relations to the remote sensingtechnology provide a new understanding of the use of polarization information on thetheory and methods. In this study we combine angle information, polarization with thesnow parameter information, not only analyze the effect of varied angle on thepolarization, the relationship between the polarized reflectance and bidirectionalreflectance, but also consider the influence of snow parameters. Strive to learn moreabout snow polarization properties based on the use of polarization informationreflects the snow parameters characteristics. This is useful for the theoretical andpartical significance for the realization of polarization remote sensing monitoring ofsnow. Also in the snow monitoring the theoretical basis of remote sensing technologyhas opened up new ideas and the direction of the broader areas of remote sensingmethods to obtain information, which can get more information for the inversion ofsnow parameters using remote sensing.更多还原