基于GOCI数据的胶州湾水体透明度遥感反演及日变化研究

Research on remote sensing retrieval and diurnal variation of Secchi disk depth of Jiaozhou Bay based on GOCI

透明度是描述海洋和湖泊水体光学性质的一个重要参数。利用2017年5月16日胶州湾航次的现场实测数据和GOCI卫星影像,采用2种半分析算法Doron11和Lee15对水体透明度进行反演。研究表明,Lee15算法在胶州湾海域表现较好,透明度反演值与实测值之间的决定系数为0.98,均方根误差为0.02 m。选择当日8幅GOCI影像,利用Lee15算法反演获得胶州湾水体透明度日变化的时空分布特征。空间分布上,海域整体透明度较低(0~4 m),从湾内到湾外透明度呈现出逐渐增大的趋势。时间变化上,湾内水体透明度的变化受潮汐影响明显,湾外和湾口的变化由太阳天顶角主导,海域平均水体透明度的变化由太阳天顶角和潮汐共同作用。根据各采样点实测水体透明度与现场同步测量的其他环境因子的统计分析,胶州湾水体透明度的变化是多个环境因子共同作用的结果,与水深存在较强的正相关,相关系数达0.84,与其他环境因子均呈负相关关系。

Secchi disk depth(Zsd)is an important parameter for describing the optical properties of water bodies.With high spatial and temporal resolution,satellite remote sensing technology has become an important method of Zsd observation.Using the in-situ measured data and GOCI images of Jiaozhou Bay(JZB)on May 16,2017,the authors used semi-analytical algorithms Doron11 and Lee15 to retrieve the Zsd.It is shown that the Lee15 performed better than Doron11,with the decision coefficient of 0.976 and the root mean square error of 0.02 m between the estimated values and in-situ measured values.Selecting eight GOCI images from 8:16 to 15:16,the authors used Lee15 algorithm to get the spatial and temporal distribution characteristics of the diurnal variation of Zsd on the JZB.On the spatial distribution,the overall Zsd level of the JZB is low(0~4 m),and gradually increases from the inside to the outside of the Bay.On the time variations,the Zsd at the Bay mouth is obviously affected by the tides.The changes between the Bay mouth and the Bay outside are dominated by the solar zenith angle(SOLZ).The change of average Zsd of the JZB is mainly caused by the joint effect of the SOLZ and the tide.According to the respectively statistical analysis between the in-situ Zsd at each sampling station and simultaneously measured other environmental factors,the change in the Zsd of the JZB is the result of the joint action of multiple environmental factors,and has a strong positive correlation with the water depth,with correlation coefficient reaching 0.84,but it is negatively correlated with other environmental factors.