基于RADARSAT-2全极化数据反演周期性地表土壤湿度

土壤湿度是农作物估产和旱情监测的关键参量。目前常用的土壤湿度反演模型都建立在随机粗糙地表条件下,对周期性垄行结构的土壤并不适用。基于RADARSAT-2全极化数据和野外实测数据,分析了交叉极化（vh）后向散射系数对垄行方位角无明显响应;同极化（hh,vv）对方位角的响应为余弦函数,但在方位角为90o±2o位置易出现偏离曲线的异常高亮度值。通过雷达影像上采样点的实测值和Oh模型推算的理论值,拟合得到周期性地表和随机地表之间的误差函数,进而对同极化影像进行纠正。纠正后的同极化比（p）去除了方位角和异常值的影响,交叉极化比（q）受到异常值的影响。通过Oh模型中的p和vh对研究区的地表参数进行反演,1...

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Bibliographic Details
Published in农业工程学报 Vol. 29; no. 17; pp. 72 - 79
Main Author 尹楠 姜琦刚 孟治国 李远华
Format Journal Article
LanguageChinese
Published 吉林大学地球探测科学与技术学院，长春 130026 2013
吉林建筑大学测绘与勘查工程学院，长春 130118%吉林大学地球探测科学与技术学院,长春,130026
Subjects
RADARSAT-2
周期性地表
土壤湿度
模型
雷达图像
models
soil moisture
模型
土壤湿度
radar imaging
周期性地表
RADARSAT-2
雷达图像
periodic surfaces
Online AccessGet full text
ISSN1002-6819
DOI10.3969/j.issn.1002-6819.2013.17.010

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Summary:土壤湿度是农作物估产和旱情监测的关键参量。目前常用的土壤湿度反演模型都建立在随机粗糙地表条件下,对周期性垄行结构的土壤并不适用。基于RADARSAT-2全极化数据和野外实测数据,分析了交叉极化（vh）后向散射系数对垄行方位角无明显响应;同极化（hh,vv）对方位角的响应为余弦函数,但在方位角为90o±2o位置易出现偏离曲线的异常高亮度值。通过雷达影像上采样点的实测值和Oh模型推算的理论值,拟合得到周期性地表和随机地表之间的误差函数,进而对同极化影像进行纠正。纠正后的同极化比（p）去除了方位角和异常值的影响,交叉极化比（q）受到异常值的影响。通过Oh模型中的p和vh对研究区的地表参数进行反演,17个检验点的验证结果表明,预测的土壤湿度平均相对误差为11.13%,标准差为0.0256cm3/cm3;预测的均方根高度平均相对误差为13%,标准差为0.1315cm。结果与随机粗糙地表土壤湿度和均方根高度的反演精度相当,证明了该模型的有效性。
Bibliography:soil moisture; models; radar imaging; periodic surfaces; RADARSAT-2
11-2047/S
Apart from surface roughness and soil moisture, the azimuth angle of a crop row is also a contributing factor of the backscattering coefficients of periodic bare soil surfaces. The commonly used models for estimating soil moisture could be applied to randomly rough surfaces, but not periodic surfaces. Based on the fully polarimetric RADARSAT-2 and field sampling data, this paper analyzes the response of backscattering coefficients to the azimuth angles of the crop rows. The like-polarized （hh or vv） backscattering is very sensitive to azimuth angles, assuming trigonometric function. Abnormal high value appears at the position around 90o. Thus, adjustment to the like-polarized backscattering coefficients is needed in order to remove the influence from azimuth angles. The cross-polarized （vh） backscattering shows a random distribution, reacting insensitively to the changes of azimuth angles. Assuming that the backscattering coefficient
ISSN:1002-6819
DOI:10.3969/j.issn.1002-6819.2013.17.010