香港近海海域叶绿素a定量反演及时空变化分析

以2009~2019年HJ-1A/B卫星多光谱数据和对应日期的实测数据为数据源，通过预处理提取出各波段组合反射率并与实测叶绿素a浓度数据进行统计相关性分析，选取相关性最高的波段组合作为特征变量与2/3的实测叶绿素a浓度数据进行建模，并用剩下的1/3实测叶绿素a浓度数据进行精度验证以确定最佳遥感反演模型，最后根据最佳反演模型对2009-2019年的香港近海海域叶绿素a浓度进行反演，明晰该海域近10年的叶绿素a浓度时空变化特征.结果表明：利用HJ-1A/B卫星多光谱数据反演香港近海海域叶绿素a浓度的最佳波段组合为第3波段和第2波段比值（B3/B2），相关系数（r）为0.893；最佳反演模型为利用B3/B2构建的e指数回归模型（Chl=0.004e^6.693(B3/B2)），决定系数（R²）为0.934，均方根误差（RMSE）为0.255μg/L，平均相对误差（RPD）为25%；近10年香港近海海域的叶绿素a浓度时空变化特征：空间上整体呈现“东高西低，由东向西逐渐减小”的分布特征，西部海域比东部海域平均浓度低5μg/L左右；2017年内呈“春低秋高，夏升冬降”的随季节变化特点，其中秋季最高，夏春两季次之，冬季最低.

Quantitative inversion and analysis of spatio-temporal changes of chlorophyll-a concentration in Hong Kong's coastal waters

This paper statistically analyzed the correlation between reflectance of different band combinations and chlorophyll-a concentration using HJ-1A/B satellite multispectral images and measured measurement from 2009 to 2019. The statistical regression analysis was performed between the band combination with the highest correlation selected as a characteristic variable and 2/3 of the total measured chlorophyll-a concentration data to build inversion models. Theses inversion models were evaluated using the rest of measured chlorophyll-a concentration data to determine the best remote sensing inversion model, which was utilized to calculate the chlorophyll-a concentration in coastal waters of Hong Kong from 2009 to 2019, and clarify the spatiotemporal characteristics of chlorophyll-a in the past 10 years. The results indicate that:The optimal band combination derived from HJ-1A/B multispectral data is the ratio of band 3and band 2 (B3/B2), which had the highest correlation with the chlorophyll-a concentration in Hong Kong's coastal waters. The correlation coefficient (r) is 0.893. The best inversion model is the e-exponential regression model (), the determination coefficient (R²) is 0.934, the root means square error (RMSE) is 0.255μg/L, and the relative average error (RPD) is 25%. The spatial distribution characteristics of chlorophyll-a concentration in Hong Kong's coastal waters is high in east and low in west, gradually decreasing from east to west in the past 10years. The average concentration of chlorophyll-a in the western waters are about 5μg/L lower than the in the eastern waters. The seasonal variation of chlorophyll-a concentration in 2017 was low in the spring, and high in the autumn, rising in the summer and dropping in the winter. The chlorophyll-a concentration is the highest in autumn, followed by summer and spring, lowest in winter.