林下枯枝落叶层双频段微波辐射衰减特性研究与分析
发布时间：2019-04-21 07:38
【摘要】：林下枯枝落叶层会衰减来自土壤的微波辐射信号,降低微波辐射亮温对地表参数变化的敏感性,从而影响林下地表参数的反演精度。为了定量研究枯枝落叶层的衰减特性,基于τ-ω模型,通过严格的理论推导证明了利用不同厚度下的枯枝落叶层亮温计算衰减系数的可行性,并基于该理论方法设计可控实验,获取了双频段(18.7GHz和36.5GHz)上不同厚度、不同重量含水量的枯枝落叶层亮温值,然后定量分析了枯枝落叶层的衰减系数随重量含水量的变化过程,同时根据计算的消光系数,分析了不同厚度、不同重量含水量下的枯枝落叶层透过率。结果表明:较干燥的枯枝落叶层的衰减系数较小,透过率较高,但是随着含水量增大,衰减系数会出现急剧的增加,从而造成透过率骤减;高频波段的衰减系数变化更加迅速,由枯枝落叶层引起的衰减作用更加明显;单次散射反照率ω随重量含水量的变化趋势为先升高后降低。该研究有利于理解森林系统中微波辐射传输过程,纠正森林区微波辐射亮温,提高森林下地表参数遥感反演精度。
[Abstract]:The litter layer under forest will attenuate the microwave radiation signal from soil, reduce the sensitivity of microwave radiation brightness temperature to the change of land surface parameters, and thus affect the inversion accuracy of land surface parameters under forest. In order to quantitatively study the attenuation characteristics of litter layer, based on 蟿-蠅 model, the feasibility of calculating attenuation coefficient by using the brightness temperature of litter layer under different thickness is proved by strict theoretical derivation. Based on the theoretical method, controllable experiments were designed to obtain the brightness temperature of litter layer with different thickness and water content in dual-band (18.7GHz and 36.5GHz). Then the variation process of decay coefficient with water content of litter layer was quantitatively analyzed. According to the calculated extinction coefficient, the transmittance of litter layer under different thickness and different weight water content was analyzed. The results show that the attenuation coefficient of the dry litter layer is smaller and the transmittance is higher, but with the increase of water content, the attenuation coefficient will increase sharply, resulting in a sharp decrease in the transmission rate. The attenuation coefficient changes more rapidly in the high frequency band, and the attenuation caused by litter layer is more obvious, and the change trend of single scattering albedo 蠅 with weight and water content is increasing first and then decreasing. This study is helpful to understand the process of microwave radiation transfer in forest system, correct the brightness temperature of microwave radiation in forest area, and improve the precision of remote sensing retrieval of land surface parameters under forest.
【作者单位】： 中国科学院东北地理与农业生态研究所;中国科学院大学;中国科学院长春净月潭遥感试验站;吉林大学地球探测科学与技术学院;
【基金】：国家自然科学基金面上项目“集成光学与微波遥感苏打盐碱地水盐含量的反演方法研究”(41371345);国家自然科学基金项目“东北地区森林下雪深被动微波遥感反演的关键影响参数观测与研究”(41471289);国家自然科学基金项目“被动微波遥感土壤水分反演精度与空间异质特征的相关性研究”(41301369)
【分类号】：TP722.6
，
本文编号：2461980
[Abstract]:The litter layer under forest will attenuate the microwave radiation signal from soil, reduce the sensitivity of microwave radiation brightness temperature to the change of land surface parameters, and thus affect the inversion accuracy of land surface parameters under forest. In order to quantitatively study the attenuation characteristics of litter layer, based on 蟿-蠅 model, the feasibility of calculating attenuation coefficient by using the brightness temperature of litter layer under different thickness is proved by strict theoretical derivation. Based on the theoretical method, controllable experiments were designed to obtain the brightness temperature of litter layer with different thickness and water content in dual-band (18.7GHz and 36.5GHz). Then the variation process of decay coefficient with water content of litter layer was quantitatively analyzed. According to the calculated extinction coefficient, the transmittance of litter layer under different thickness and different weight water content was analyzed. The results show that the attenuation coefficient of the dry litter layer is smaller and the transmittance is higher, but with the increase of water content, the attenuation coefficient will increase sharply, resulting in a sharp decrease in the transmission rate. The attenuation coefficient changes more rapidly in the high frequency band, and the attenuation caused by litter layer is more obvious, and the change trend of single scattering albedo 蠅 with weight and water content is increasing first and then decreasing. This study is helpful to understand the process of microwave radiation transfer in forest system, correct the brightness temperature of microwave radiation in forest area, and improve the precision of remote sensing retrieval of land surface parameters under forest.
【作者单位】： 中国科学院东北地理与农业生态研究所;中国科学院大学;中国科学院长春净月潭遥感试验站;吉林大学地球探测科学与技术学院;
【基金】：国家自然科学基金面上项目“集成光学与微波遥感苏打盐碱地水盐含量的反演方法研究”(41371345);国家自然科学基金项目“东北地区森林下雪深被动微波遥感反演的关键影响参数观测与研究”(41471289);国家自然科学基金项目“被动微波遥感土壤水分反演精度与空间异质特征的相关性研究”(41301369)
【分类号】：TP722.6
，
本文编号：2461980
本文链接：https://www.wllwen.com/guanlilunwen/gongchengguanli/2461980.html
