Comparative Analysis of Four Models to Estimate Chlorophyll-a Concentration in Case-2 Waters Using MODerate Resolution Imaging Spectroradiometer (MODIS) Imagery

Remote Sensing

Anas El-Alem¹  Karem Chokmani¹  Isabelle Laurion¹ 

[1]Centre Eau Terre Environnement, INRS, 490 de la Couronne, Québec, QC G1K 9A9, Canada

[2] E-Mail:

关键词: remote sensing;    MODIS;    Chl-a;    lake;    HABs;    Quebec;    Champlain;   

DOI  :  10.3390/rs4082373

来源: mdpi

【 摘 要 】

The occurrence and extent of intense harmful algal blooms (HABs) have increased in inland waters during recent decades. Standard monitor networks, based on infrequent sampling from a few fixed observation stations, are not providing enough information on the extent and intensity of the blooms. Remote sensing has great potential to provide the spatial and temporal coverage needed. Several sensors have been designed to study water properties (AVHRR, SeaBAM, and SeaWIFS), but most lack adequate spatial resolution for monitoring algal blooms in small and medium-sized lakes. Over the last decade, satellite data with 250-m spatial resolution have become available with MODIS. In the present study, three models inspired by published approaches (Kahru, Gitelson, and Floating Algae Index (FAI)) and a new approach named APPEL (APProach by ELimination) were adapted to the specific conditions of southern Quebec and used to estimate chlorophyll-a concentration (Chl-a) using MODIS data. Calibration and validation were provided from in situ Chl-a measured in four lakes over 9 years (2000–2008) and concurrent MODIS imagery. MODIS bands 3 to 7, originally at 500-m spatial resolution, were downscaled to 250 m. The APPEL, FAI, and Kahru models yielded satisfactory results and enabled estimation of Chl-a for heavy blooming conditions (Chl-a > 50 mg·m⁻³), with coefficients of determination reaching 0.95, 0.94, and 0.93, respectively. The model inspired from Gitelson did not provide good estimations compared to the others (R² = 0.77). However, the performance of all models decreased when Chl-a was below 50 mg·m⁻³.

【 授权许可】

CC BY   
© 2012 by the authors; licensee MDPI, Basel, Switzerland.