结构函数法反演气溶胶光学厚度中像元的间隔设置
Pixel distance settings in aerosol optical depth retrieval through the structure function method
- 2016年20卷第4期 页码:528-539
纸质出版日期: 2016
DOI: 10.11834/jrs.20164287
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纸质出版日期: 2016 ,
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[1]朱琳,孙林,杨磊,徐菲菲,徐青山.结构函数法反演气溶胶光学厚度中像元的间隔设置[J].遥感学报,2016,20(04):528-539.
ZHU Lin, SUN Lin, YANG Lei, et al. Pixel distance settings in aerosol optical depth retrieval through the structure function method[J]. Journal of Remote Sensing, 2016,20(4):528-539.
结构函数法气溶胶光学厚度反演精度受像元间隔设置影响很大
且并非所有像元都能获得较好的反演结果
因而研究像元间隔的设置能够提高反演精度
研究反演误差小的像元能够提高算法效率。为了获得最佳的像元间隔设置
本文以胶州湾地区为例
利用250 m和500 m两种分辨率数据计算了不同像元间隔时的结构函数值
分别利用单一像元间隔法、均值法、坡高法以及线性区域均值法获得待反演像元最终的结构函数值反演550 nm处的气溶胶光学厚度
并依据CE318观测数据进行精度验证
通过分析点对点反演结果和光学厚度的空间分布
确定反演误差小、受分辨率影响小的像元间隔设置。实验发现线性区域均值法在一定程度上提高了反演精度和稳定性。此外
通过对反演结果可接受像元的地表反射率结构函数值的统计和分析
发现500 m分辨率时可接受像元比例优于250 m
当地表反射率结构函数值大于0.02时反演结果较好
而这些像元往往分布在山麓、山涧、海岸线、河流、城乡结合部等地理要素的突然改变的地区。
Retrieval of Aerosol Optical Depth(AOD)over land through satellite remote sensing is difficult. Traditional methods to retrieve aerosol over land involve the use of the Dense Dark Vegetation(DDV) algorithm. However
this algorithm requires the support of an infrared band and dark pixels. Compared with DDV
the structure function method can be utilized to retrieve AOD over bright areas with high surface reflectance. However
the precision of retrieving AOD through the structure function method can be significantly influenced by pixel distance. Not all pixels can be retrieved with high precision; this condition results in a large amount of unnecessary computations. As a result
determining the pixel distance settings and the pixels with a small retrieval error is important in improving the retrieval precision and efficiency of the structure function method.To acquire the best pixel distance settings
we calculated the structure function values with different pixel distances and obtained the final structure function value of the target pixel through single-pixel distance
average
slopeheight
and average linear area methods to retrieve AOD at 550 nm over Kiaochow Bay. The first band of nine-scene MODIS L1 B data with resolutions of 250 m and 500 m was used.Surface reflectance was the minimum value of the first band of MOD09Q1 in 2012. By validating the AOD data measured by CE318 and by analyzing the retrieval result and spatial distribution of AOD
we obtained the pixel distance settings with high precision and minimal effects of resolution. The experiment indicated that the average linear area method has a small retrieval error whether the resolution is 250 m or 500 m. According to statistics and by analyzing the structure function value of the surface reflectance of pixels with an acceptable error(the absolute value of the absolute error is 0.1 for measured AOD less than 0.6 and 0.2 for measured AOD greater than 0.6)
we found that the ratio of pixels with are solution of 500 m is obviously larger than that with 250 m resolution. Pixels with a surface reflectance structure function value larger than 0.02 have a good result and areaways distributed over areas with a sudden change in geographical elements
such as piedmonts
mountain streams
coasts
rivers
and rural–urban continua. In this study
we utilized different methods and historical surface reflectance data with two resolutions to calculate the final structure function value. The retrieval precision and distribution of AOD were analyzed to acquire the best pixel distance settings
and its features were identified through the statistics of the structure function values with high retrieval precision. The average linear area method is stable
and its result has an insignificant relationship with data resolution. The retrieved AOD with high precision is concentrated on pixels with a surface reflectance structure function value larger than 0.02. The efficiency of this method increases when the measured AOD is greater than0.5.
结构函数法地表反射率表观反射率像元间隔气溶胶光学厚度
structure function methodsurface reflectanceapparent reflectancepixel distanceAOD(Aerosol Optical Depth)
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