基于BRDF校正的上海近海水体叶绿素a浓度反演

Inversion of Chlorophyll-a Concentration in Shanghai Offshore Waters Based on BRDF Correction

为了探究上海近海区水体生态状况,采用水色遥感技术,对叶绿素a浓度进行反演,考虑BRDF对反演的影响,基于Landsat-8遥感数据和水质实测数据,结合Lee模型和QAA算法对上海近海水体进行BRDF校正。结果表明:悬浮泥沙浓度是影响水体BRDF的主要原因之一;日光在非垂直入射时,角度对水体BRDF影响较小;BRDF校正后模型R2平均值达到0.9,提高了22.2%,RMSE平均值降低至0.74;BRDF校正前上海近海区叶绿素a浓度平均被高估2 mg/m^(3)。通过BRDF校正提高了叶绿素a反演精度,为近海水体水色反演研究提供新思路。

To investigate the ecological status of Shanghai’s offshore waters,we applied the water color remote sensing technology to estimate chlorophyll-a concentration.Considering the impact of BRDF(Bidirectional Reflectance Distribution Function)on inversion accuracy,we utilized LandSat-8 remote sensing data and measured water quality data in association with Lee’s model and QAA(Quasi-analytical algorithm)for BRDF correction.Results indicate that suspended sediment concentration is a major factor affecting BRDF.The angle of sunlight has minimal impact on BRDF when the sun is not vertically incident.After BRDF correction,the mean value of R 2 increased by 22.2%to 0.9,whereas mean RMSE decreased to 0.74.Before the correction,chlorophyll-a concentrations in Shanghai’s offshore waters were overestimated by an average of 2 mg/m^(3).BRDF correction notably enhances chlorophyll-a inversion accuracy,presenting innovative insights for offshore water color inversion.