摘要
积雪的被动微波辐射亮温信号十分复杂,深度、温度、粒径、密度、液态水含量,以及下垫面的状况都会不同程度的影响积雪层的亮度温度。本文利用多层积雪微波辐射模型(MEMLS)分别针对各个输入参数对模拟亮温的影响进行了分析,发现粒径是敏感性最高的模型参数,湿度、深度、密度、积雪温度次之。模型模拟结果表明,当雪深小于50cm时,雪深可以近似地表示为19和37GHz的亮温差的线性函数;当雪深大于50cm后,随着雪深的增加,亮温差增加幅度变小,趋向于饱和。在建立积雪深度反演公式时,粒径和密度会影响公式的拟合系数。把一定区域内积雪粒径和密度看作是相同的值,这可能是造成被动微波遥感反演雪深和雪水当量误差的原因之一。被动微波无法反演湿雪的雪深和雪水当量,但可以有效识别干雪和湿雪,为水文模拟以及农业灌溉提供科学的依据和信息。积雪温度对积雪辐射亮温影响较小,而且在对积雪深度进行反演时,两个频率亮温值相减,温度的影响也被降到了最低。
There are various factors that impact passive microwave responses of snow.These factors include depth,crystal size,wetness,density and temperature of snow.In this paper,a sensitivity study was carried out based on Microwave Emission Model of Layered Snowpacks（MEMLS）model.The result showed that grain size made the most effect on the output of the model,while depth,wetness,density,and snow temperature are in the next place.The relation between snow depth and the difference between 19 and 37GHz brightness temperature can be described by a linear formula when the snow depth is less than 50cm,while the range of increase will slow down and tend to a saturation when the snow depth is large than 50cm.Snow density and grain size can greatly influence the coefficient of the linear formula.The passive microwave remote sensing data could not reflect snow depth and snow water equivalent when snow is wet because liquid water significantly changes the permittivity of dry snow.The difference of snow t emperature at different channels can reduce the effect of brightness temperature on the estimation of snow depth.
出处
《遥感技术与应用》
CSCD
北大核心
2009年第5期622-630,共9页
Remote Sensing Technology and Application
基金
中国科学院西部行动计划(二期)项目"黑河流域遥感-地面观测同步试验与综合模拟平台建设"(KZCX2-XB2-09)
财政部/科技部公益类行业专项(GYHY(QX)2007-6-18)资助
关键词
积雪被动微波遥感
敏感性分析
Passive microwave remote sensing of snow
Sensitivity analysis
