光谱学与光谱分析
光譜學與光譜分析
광보학여광보분석
SPECTROSCOPY AND SPECTRAL ANALYSIS
2014年
2期
477-482
,共6页
韩留生%陈水森%陈修治%李丹%李勇%孙林%卢楚谦%陈玮琦
韓留生%陳水森%陳脩治%李丹%李勇%孫林%盧楚謙%陳瑋琦
한류생%진수삼%진수치%리단%리용%손림%로초겸%진위기
近海岸%透明度%光谱模型%半分析算法
近海岸%透明度%光譜模型%半分析算法
근해안%투명도%광보모형%반분석산법
Offshore%Water clarity%Spectra model%Semi-analysis algorithm
针对近海岸混浊水体透明度的分析和半分析算法中吸收系数和散射系数难以获得的难题,试图构建一个不需要计算吸收系数和散射系数且适用于近海透明度的半分析反演模型。基于Preisendorfer(1986)和Tyler(1968)提出的Zsd(Secchi depth)反演理论,综合490 nm处垂直漫衰减系数 Kd (490)和光束衰减系数 c(490)与遥感反射率的关系,建立了以两波段遥感反射率比值和潮汐系数修正的适用于近海岸海水透明度反演的简易半分析光谱模型。将此半分析光谱模型应用于珠江口生态区(2012年10月21日-23日、2012年11月2日)和徐闻珊瑚礁自然保护区(2013年1月13日-14日)的透明度反演。利用同步实测数据验证发现,大潮期间,该模型计算的透明度与实测值整体偏高0.4m左右,小潮期间,该模型计算的透明度比实测值比较吻合。因此对该模型做了潮汐系数修正,潮汐修正后反演的透明度与实测数值的决定系数为0.663,绝对平均误差为0.14 m ,相对平均误差为19.5%。综合表明,该模型只需要490与560 nm两个波段处遥感反射率的比值即可完成透明度的反演,且模型相对简便,透明度反演精度相对较高。
針對近海岸混濁水體透明度的分析和半分析算法中吸收繫數和散射繫數難以穫得的難題,試圖構建一箇不需要計算吸收繫數和散射繫數且適用于近海透明度的半分析反縯模型。基于Preisendorfer(1986)和Tyler(1968)提齣的Zsd(Secchi depth)反縯理論,綜閤490 nm處垂直漫衰減繫數 Kd (490)和光束衰減繫數 c(490)與遙感反射率的關繫,建立瞭以兩波段遙感反射率比值和潮汐繫數脩正的適用于近海岸海水透明度反縯的簡易半分析光譜模型。將此半分析光譜模型應用于珠江口生態區(2012年10月21日-23日、2012年11月2日)和徐聞珊瑚礁自然保護區(2013年1月13日-14日)的透明度反縯。利用同步實測數據驗證髮現,大潮期間,該模型計算的透明度與實測值整體偏高0.4m左右,小潮期間,該模型計算的透明度比實測值比較吻閤。因此對該模型做瞭潮汐繫數脩正,潮汐脩正後反縯的透明度與實測數值的決定繫數為0.663,絕對平均誤差為0.14 m ,相對平均誤差為19.5%。綜閤錶明,該模型隻需要490與560 nm兩箇波段處遙感反射率的比值即可完成透明度的反縯,且模型相對簡便,透明度反縯精度相對較高。
침대근해안혼탁수체투명도적분석화반분석산법중흡수계수화산사계수난이획득적난제,시도구건일개불수요계산흡수계수화산사계수차괄용우근해투명도적반분석반연모형。기우Preisendorfer(1986)화Tyler(1968)제출적Zsd(Secchi depth)반연이론,종합490 nm처수직만쇠감계수 Kd (490)화광속쇠감계수 c(490)여요감반사솔적관계,건립료이량파단요감반사솔비치화조석계수수정적괄용우근해안해수투명도반연적간역반분석광보모형。장차반분석광보모형응용우주강구생태구(2012년10월21일-23일、2012년11월2일)화서문산호초자연보호구(2013년1월13일-14일)적투명도반연。이용동보실측수거험증발현,대조기간,해모형계산적투명도여실측치정체편고0.4m좌우,소조기간,해모형계산적투명도비실측치비교문합。인차대해모형주료조석계수수정,조석수정후반연적투명도여실측수치적결정계수위0.663,절대평균오차위0.14 m ,상대평균오차위19.5%。종합표명,해모형지수요490여560 nm량개파단처요감반사솔적비치즉가완성투명도적반연,차모형상대간편,투명도반연정도상대교고。
The main objectives of the research described in the present paper are to develop a semi-analysis model of water clarity for case 2 waters without inputting the absorption and scattering coefficient ,which are not easy to be obtained for offshore ma-rine areas so far .Based on the Zsd(Secchi depth)inversion theory ,a simple semi-analysis spectra model was established for off-shore seawater clarity by analyzing the relationship between vertical diffuse attenuation coefficient Kd (490) and the beam attenu-ation coefficient c(490) with remote sensing reflectance .This semi-analysis spectra model needed two band reflectance ratios on-ly ,while tidal correction was produced for this model to improve the precision of the retrieving results .The semi-analysis spectra model was applied to ASD hyperspectral reflectance data measured in the Pearl River Estuary Ecological Zone (October 21 ,23 , 2012 ,November 2 ,2012 ;N=20) and the Xuwen Coral Reef Protection Zone (January 13 ,14 ,2013 , N=25) which covered different water body of tidal times and different pollution sources .The results indicated that the changing tendency of predicted values was consistent with the synchronous measurement values after comparing them .However ,water clarity calculated by the ASD hyperspectral reflectance measured in spring tidal time ,generated 0.4 m deviation compared with in-situ water clarity , while water clarity calculated by the ASD hyperspectral reflectance measured in neap tidal time is close to the in-situ water clari-ty .So the tidal correction coefficient of 0.4 was further applied for the model .After modification ,the coefficient of determina-tion between the inversed and measured water clarity was 0.663 ,the average absolute error was 0.14 m and the average relative error was 19.5% .Research demonstrated that this semi-analysis inversion algorithm just needs two band reflectance ratio to complete the inversion of water clarity ,which is simple and works relatively well for lower clarity (less than 2 meters) waters compared to He’(2004) and Doron’(2011) algorithms .