北冰洋有色溶解有机物与溶解有机碳遥感监测

Remote Sensing Monitoring of Colored Dissolved Organic Matter and Dissolved Organic Carbon in the Arctic Ocean

  • 摘要: 借助MODIS卫星数据,利用准分析算法(Quasi-Analytical Algorithm,QAA)反演得到2010年与2011年夏季北冰洋表层水体有色溶解有机物(Colored Dissolved Organic Matter,CDOM)吸收系数,并依据实测反射率数据将CDOM与溶解有机碳(Dissolved Organic Carbon,DOC)分类,研究不同波段(412、443、490、532、555、667 nm)、不同类别的CDOM与DOC的相关性差异,在此基础上建立增强回归树模型,分析影响DOC质量浓度变化的主要驱动因素。结果表明:使用QAA反演北冰洋表层水体CDOM吸收系数具有较高的精度;反射波峰位于555 nm时,CDOM与DOC相关性(R2=0.95)高于整体相关性(R2=0.94),CDOM的反演精度更高(R2=0.88,MRE=28.6%);反射峰位于490或465 nm时,CDOM与DOC相关性较弱(R2=0.76),CDOM的反演精度较低(R2=0.37,MRE=36.4%)。影响因素分析表明,CDOM、悬浮颗粒物以及叶绿素a是影响北冰洋夏季DOC质量浓度变化的主要驱动因素。

     

    Abstract: With the help of MODIS satellite data, the QAA (Quasi-Analytical Algorithm) algorithm was used to obtain the absorption coefficient of colored dissolved organic matter (CDOM) in the surface waters of the Arctic Ocean during the summer of 2010 and 2011. CDOM and DOC were classified according to the field measured reflectance data, and the correlation differences between CDOM and DOC in different bands (412, 443, 490, 532, 555, 667 nm ) and different categories were studied. Finally, a boosted regression tree model was developed to analyze the main driving factors of DOC concentration changes. The results show that the inversion of CDOM absorption coefficients in surface waters of the Arctic Ocean using the QAA algorithm is highly feasible. In addition, classification based on peak reflectance could improve the inversion accuracy. When the peak reflectance located in 555 nm, the correlation between CDOM and DOC (R2=0.95) was higher than overall correlation (R2=0.94), and the inversion accuracy of CDOM was relatively high (R2=0.88, MRE=28.6%). In comparison, when the peak reflectance located in 490 or 465 nm, the correlation between CDOM and DOC (R2=0.76) was weak, and the inversion accuracy of CDOM was relatively low (R2=0.37, MRE=36.4%). Analysis of influencing factors shows that CDOM, suspended particulate matter, and chlorophyll-a were the main drivers of DOC concentration changes in the Arctic Ocean during summer.

     

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