基于Sentinel-3 OLCI影像的渤海FUI水色指数遥感提取及应用

水色是水体水文学特征的基本要素之一。水色测定主要是采用福莱尔比色表(Forel-Ule Scale)将自然水体按颜色从深蓝到红棕共分为21个级别,用以观测、记录海洋和内陆水体的颜色。基于2020—2021年大辽河口、黄河口西南及秦皇岛近岸海域的现场实测数据和同步Sentinel-3 OLCI影像,验证了FUI水色指数遥感提取结果的准确性,发现当现场测量时间与卫星过境时间接近时,FUI水色指数遥感提取结果与实测结果基本一致。利用2021年1—12月Sentinel-3 OLCI影像,提取了渤海月均FUI水色指数遥感产品,发现渤海FUI水色指数的主要变化区间为5~17,整体呈现辽东湾、渤海湾及莱州湾沿岸海域高,秦皇岛海域及其他离岸海域低的空间分布特征,且存在秋冬季高、春夏季低的时间变化规律。此外,FUI水色指数对诸多海洋生态环境问题具有显著的指示功能。尝试将其应用于海洋水色异常和海水水质类别观测,均取得了较好的应用效果。由此可见,FUI水色指数遥感提取将在今后的海洋生态环境监测与评价方面发挥重要作用。

Extraction and Application of Forel-Ule Index from Sentinel-3 OLCI Image in the Bohai Sea

Water color is a basic element of hydrology.The Forel-Ule scale is used to divide the color of natural water bodies from dark blue to reddish brown into 21 levels,and observe and record the colors of ocean and inland water bodies.Based on the in-situ measured data and synchronized Sentinel-3 OLCI images of the coastal waters of Daliao River,southwest of Yellow River Delta and Qinhuangdao from 2020 to 2021,the extraction accuracy of the FUI water color index was verified,and it was found that when the in-site measured time was close to sensing time,the extraction results were basically consistent with the observation results.Using Sentinel-3 OLCI images from January to December 2021,we extracted the Bohai Sea monthly average FUI color index,and found that the main change interval of FUI color index was 5-17.The overall appearance was high in the coastal waters of Liaodong Bay,Bohai Bay and Laizhou Bay,low in Qinhuangdao waters and other offshore waters,and high in autumn and winter,and low in spring and summer.In addition,the FUI color index had a significant indicator function for many marine ecological and environmental problems.This article tried to apply it to the observation of ocean water color anomalies and sea water quality categories,and achieved good application results.The FUI color index might play an important role in marine ecological environment monitoring and evaluation in the future.