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基于不同分辨率DEM提取坡长的统计分布 被引量:5
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作者 郭伟玲 樊宇 杨勤科 《水土保持研究》 CSCD 北大核心 2019年第3期72-76,85,共6页
坡长是土壤侵蚀和流域水文等研究的重要地形指标,在流域或区域土壤侵蚀评价研究中,坡长通常基于中低分辨率DEM提取,但随着DEM分辨率的降低,其上提取的坡长发生扩张,进而影响土壤侵蚀评价的计算精度。DEM分辨率对坡长的影响虽已受到注意... 坡长是土壤侵蚀和流域水文等研究的重要地形指标,在流域或区域土壤侵蚀评价研究中,坡长通常基于中低分辨率DEM提取,但随着DEM分辨率的降低,其上提取的坡长发生扩张,进而影响土壤侵蚀评价的计算精度。DEM分辨率对坡长的影响虽已受到注意,但对于这种影响的机理尚不清楚。因此本研究采用对坡长表面采用分级研究的方法,分析了坡长随DEM分辨率的统计分布变化的规律。结果表明:随着分辨率的降低,整体上表现为短坡长向中等坡长区扩张,长坡长出现衰减,坡长整体集中分布在中等坡长区域,基于此提出了因分辨率降低引起坡长表面变化的定量表述公式及坡长误差经验公式,可以根据坡长提取精度需求来计算合适的分辨率参数,为选取合适的DEM分辨率提高坡长计算效率提供依据。 展开更多
关键词 坡长 数字高程模型 空间分辨率 误差经验公式
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Empirical ocean color algorithm for estimating particulate organic carbon in the South China Sea 被引量:4
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作者 胡水波 曹文熙 +5 位作者 王桂芬 许占堂 赵文静 林俊芳 周雯 姚林杰 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2015年第3期764-778,共15页
We examined regional empirical equations for estimating the surface concentration of particulate organic carbon (POC) in the South China Sea. These algorithms are based on the direct relationships between POC and th... We examined regional empirical equations for estimating the surface concentration of particulate organic carbon (POC) in the South China Sea. These algorithms are based on the direct relationships between POC and the blue-to-green band ratios of spectral remotely sensed reflectance, Rrs(λB)/Rrs(555). The best error statistics among the considered formulas were produced using the power function POC (rag/ m3)=262.173 [Rrs(443)/Rrs(555)]^-0.940. This formula resulted in a small mean bias of approximately -2.52%, a normalized root mean square error of 31.1%, and a determination coefficient of 0.91. This regional empirical equation is different to the results of similar studies in other oceanic regions. Our validation results suggest that our regional empirical formula performs better than the global algorithm, in the South China Sea. The feasibility of this band ratio algorithm is primarily due to the relationship between POC and the green-to- blue ratio of the particle absorption coefficient. Colored dissolved organic matter can be an important source of noise in the band ratio formula. Finally, we applied the empirical algorithm to investigate POC changes in the southwest of Luzon Strait. 展开更多
关键词 particulate organic carbon (POC) ocean color algorithm South China Sea (SCS) MODIS remote sensing
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