Journal of The Remote Sensing Society of Japan
Online ISSN : 1883-1184
Print ISSN : 0289-7911
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Volume 30 , Issue 4
Showing 1-9 articles out of 9 articles from the selected issue
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Foreword
Papers
  • Jun KOMUKAI, Ke'ichi OKAMOTO, Shoichi SHIGE, Takeshi MANABE
    Volume 30 (2010) Issue 4 Pages 221-233
    Released: March 13, 2012
    JOURNALS FREE ACCESS
    The Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) standard algorithm 2A21 produces the surface normalized radar cross section (NRCS) values under no rain conditions as functions of the incidence angle and surface physical parameters which affect surface scattering. These NRCS values are used as the reference values to calculate the path integrated attenuation (PIA) values in the surface reference technique (SRT) to perform the rain attenuation correction. This paper (Part I) shows the NRCS values as functions of incidence angle and wind speed over the ocean and tries to improve the methods to calculate reference NRCS values over ocean, and the following paper (Part II) concerns NRCS over the land.
    We analyze statistically the ocean surface NRCS as a function of incidence angle over the eleven years from 1998 to 2008. The relation between the NRCS and the incidence angle is approximated better by the two quadratic curves than the single quadratic curve. This approximation will improve the across-track hybrid method used to calculate the reference NRCS in the present PR 2A21 version 6 algorithm. The present PR 2A21 version 6 algorithm also uses the temporal reference method to calculate the reference NRCS only as a function of incidence angle over the ocean. We introduce a new equation which expresses the NRCS not only by the incidence angle but also by the ocean surface wind speed. This equation is expected to improve the reference NRCS in the temporal reference method over the ocean. The relation between the NRCS and the relative wind direction is also studied by comparing the TRMM PR NRCS and the wind direction observed by Seawinds on the QuikSCAT. Best-fit approximation curve shows the slight dependence of the NRCS on the relative wind direction.
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  • Jun KOMUKAI, Ke'ichi OKAMOTO, Shoichi SHIGE, Takeshi MANABE
    Volume 30 (2010) Issue 4 Pages 234-247
    Released: March 13, 2012
    JOURNALS FREE ACCESS
    The Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) standard algorithm 2A21 produces the surface normalized radar cross section (NRCS) values under no rain conditions as functions of the incidence angle and surface physical parameters which affect surface scattering. These NRCS values are used as the reference values to calculate the path integrated attenuation (PIA) values in the surface reference technique (SRT) to perform the rain attenuation correction. This paper (Part II) shows the relation between the land surface NRCS values and the three land surface physical parameters which are NDVI (Normalized Differential Vegetation Index), the surface roughness, and the soil moisture over the land for each of the incidence angles and tries to improve the methods to calculate reference NRCS values over the land.
    We calculate the correlation coefficients and derive the linear regression equation between the land surface NRCS and each of the tree land surface physical parameters for each of the incidence angles, respectively. The present PR 2A21 version 6 algorithm uses the temporal reference method to calculate the reference NRCS as a function of incidence angle only over the land. We apply the multiple regression analyses between the NRCS and all of the tree land surface physical parameters at a time and derive the new equations which express the NRCS by the tree land surface physical parameters for each of the incidence angles. This equation is expected to improve the reference NRCS in the temporal reference method over the land.
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