Estimating chlorophyll-a concentration based on a four-band model using field spectral measurements and HJ-1A hyperspectral data of Qiandao Lake, China

• Published in: Remote sensing letters Vol. 6; no. 10; pp. 735 - 744
• Main Authors: Feng, Quanlong, Gong, Jianhua, Wang, Ying, Liu, Jiantao, Li, Yi, Ibrahim, A.N, Liu, Qigen, Hu, Zhongjun
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 03.10.2015; Taylor & Francis Ltd
• Subjects: Calibration; China; Chlorophyll; Estimating; lakes; Phytoplankton; reflectance; Remote sensing; Satellite imagery; Satellites; spatial data; Spectra; spectral analysis; Tuning; variance; wavelengths; China
• ISSN: 2150-7058; 2150-704X; 2150-7058
• DOI: 10.1080/2150704X.2015.1054044

Accurate estimation of phytoplankton chlorophyll- a (chl- a) concentration from remote sensing data is challenging due to the complex optical properties of case II waters. Recently, a novel semi-analytical four-band model was developed to estimate chl- a concentration in turbid productive waters. The objective of this study was to evaluate the performance of the four-band model and extend its application to hyperspectral satellite data for estimating chl- a concentration in Qiandao Lake of China. Based on field spectral measurements and in situ water sampling, the four-band model expressed as [ R ᵣₛ⁻¹(661.6) – R ᵣₛ⁻¹(706.7)] [ R ᵣₛ⁻¹(714.8) – R ᵣₛ⁻¹(682.2)] ⁻¹ was calibrated after band tuning, where R ᵣₛ⁻¹ represents the reciprocal of the remote sensing reflectance. The spectral-based four-band model accounted for more than 88% of variance in chl- a concentration with a root mean square error (RMSE) of 1.47 μg l ⁻¹. To justify the potential of this model with satellite data, comparable wavelengths selected from HJ-1A Hyperspectral Imager (HSI) imagery were utilized to calibrate the four-band model. The HSI-based model explained about 80% of chl- a variation with an RMSE of 1.35 μg l ⁻¹. Experimental results also showed that the four-band model outperformed its three-band counterpart. The results validated the rationale of the four-band model and demonstrated the effectiveness of this model for estimating chl- a concentration from both in situ spectral data and HJ-1A hyperspectral satellite imagery.