基于Landsat-5 TM数据和地面同步水质监测数据发现,近红外波段与红色波段比值与叶绿素a实测浓度存在较高相关性,并以此建立了提取水体表层叶绿素a浓度的遥感信息模型.经验证,该模型用于叶绿素a浓度反演的精度良好,平均相对误差为14.5％.将该模型应用于Landsat卫星系列数据,提取了东平湖1985-2015年每年度丰水期叶绿素a浓度信息,得到共31幅东平湖叶绿素a浓度分布图,并对其进行了时空分析.结果表明:1985-2015年,东平湖叶绿素a平均浓度范围为32.4 ～81.4 μg/L,空间分布上一般表现为湖周边浅水区高于湖中心深水区,且空间差异变化明显;时间序列上,东平湖叶绿素a浓度表现出一定的波动性,在1987、1988、1992年出现较高值,总体看来,在95％置信水平上秩相关系数为-0.592,浓度呈下降趋势.%The ratio of near infrared and red bands have shown to be sensitive to the chlorophyll-a concentration based on the regression analysis between Landsat-5 images and synchronous in-situ water quality monitoring data.Model estimating water chlorophyll-a concentration was proposed and its average relative error was only 14.5％.The information of chlorophyll-a concentration in Dongping Lake among thirty years (1985-2015) was extracted by the model.The results showed that chlorophyll-a concentration in Dongping Lake fluctuated with the range of 32.4-81.4 μg/L and had significant spatial differences from 1985 to 2015.The highest value appeared in 1997,1988 and 1992.Generally,under the rank correlation coefficient was -0.592 at the 95％ confidence level,chlorophyll-a concentration showed a downward trend.
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