中国地理科学(英文版) ›› 2010, Vol. 20 ›› Issue (4): 345-352.doi: 10.1007/s11769-010-0407-3

• 论文 • 上一篇    下一篇

A Method for Surface Roughness Parameter Estimation in Passive Microwave Remote Sensing

ZHENG Xingming1,2, ZHAO Kai1   

  1. 1. Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130012, China;
    2. Graduate University of the Chinese Academy of Sciences, Beijing 100049, China
  • 收稿日期:2010-01-13 修回日期:2010-04-02 出版日期:2010-07-01 发布日期:2010-08-23
  • 通讯作者: ZHAO Kai.E-mail:zhaokai@neigae.ac.cn E-mail:zhaokai@neigae.ac.cn
  • 基金资助:

    Under the auspices of the Key Direction in Knowledge Innovation Programs of Chinese Academy of Sciences (No.KZCX2-YW-340)

A Method for Surface Roughness Parameter Estimation in Passive Microwave Remote Sensing

ZHENG Xingming1,2, ZHAO Kai1   

  1. 1. Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130012, China;
    2. Graduate University of the Chinese Academy of Sciences, Beijing 100049, China
  • Received:2010-01-13 Revised:2010-04-02 Online:2010-07-01 Published:2010-08-23
  • Supported by:

    Under the auspices of the Key Direction in Knowledge Innovation Programs of Chinese Academy of Sciences (No.KZCX2-YW-340)

摘要:

Surface roughness parameter is an important factor and obstacle for retrieving soil moisture in passive microwave remote sensing.Two statistical parameters,root mean square (RMS) height (s) and correlation length (l),are designed for describing the roughness of a randomly rough surface.The roughness parameter measured by traditional way is independence of frequency,soil moisture and soil heterogeneity and just the "geometric" roughness of random surface.This "geometric" roughness can not fully explain the scattered thermal radiation by the earth's surface.The relationship between "geometric" roughness and integrated roughness (contain both "geometric" roughness and "dielectric" roughness) is linked by empirical coefficient.In view of this problem,this paper presents a method for estimating integrated surface roughness from radiometer sampling data at different frequencies,which mainly based on the flourier relationship between power spectral density distribution and spatial autocorrelation function.We can obtain integrated surface roughness at different frequencies by this method.Besides "geometric" roughness,this integrated surface roughness not only contains "dielectric" roughness but also includes frequency dependence.Combined with Q/H model the polarization coupling coefficient can also be obtained for both H and V polarization.Meanwhile,the simulated numerical results show that radiometer with a sensitivity of 0.1 K can distinguish the different surface roughness and the change of roughness with frequency for the same rough surface.This confirms the feasibility of radiometer sampling method for estimating the surface roughness theoretically.This method overcomes the problem of "dielectric" roughness measurement to some extent and can achieve the integrated surface roughness within a microwave pixel which can serve soil moisture inversion better than the "geometric" roughness.

关键词: surface roughness, passive microwave remote sensing, statistical parameter estimation, soil moisture, radiometer

Abstract:

Surface roughness parameter is an important factor and obstacle for retrieving soil moisture in passive microwave remote sensing.Two statistical parameters,root mean square (RMS) height (s) and correlation length (l),are designed for describing the roughness of a randomly rough surface.The roughness parameter measured by traditional way is independence of frequency,soil moisture and soil heterogeneity and just the "geometric" roughness of random surface.This "geometric" roughness can not fully explain the scattered thermal radiation by the earth's surface.The relationship between "geometric" roughness and integrated roughness (contain both "geometric" roughness and "dielectric" roughness) is linked by empirical coefficient.In view of this problem,this paper presents a method for estimating integrated surface roughness from radiometer sampling data at different frequencies,which mainly based on the flourier relationship between power spectral density distribution and spatial autocorrelation function.We can obtain integrated surface roughness at different frequencies by this method.Besides "geometric" roughness,this integrated surface roughness not only contains "dielectric" roughness but also includes frequency dependence.Combined with Q/H model the polarization coupling coefficient can also be obtained for both H and V polarization.Meanwhile,the simulated numerical results show that radiometer with a sensitivity of 0.1 K can distinguish the different surface roughness and the change of roughness with frequency for the same rough surface.This confirms the feasibility of radiometer sampling method for estimating the surface roughness theoretically.This method overcomes the problem of "dielectric" roughness measurement to some extent and can achieve the integrated surface roughness within a microwave pixel which can serve soil moisture inversion better than the "geometric" roughness.

Key words: surface roughness, passive microwave remote sensing, statistical parameter estimation, soil moisture, radiometer