A Wavelet Approach for Estimating Chlorophyll-A From Inland Waters With Reflectance Spectroscopy

E.M. Ampe, Erin Hestir, Mariano Bresciani, E. Salvadore, Vittorio Brando, Arnold Dekker, Tim Malthus, Maarten Jansen, L Triest, Okke Batelaan

    Research output: Contribution to journalArticle

    12 Citations (Scopus)

    Abstract

    This letter presents an application of continuous wavelet analysis, providing a new semi-empirical approach to estimate Chlorophyll-A (Chl-A) in optically complex inland waters. Traditionally spectral narrow band ratios have been used to quantify key diagnostic features in the remote sensing signal to estimate concentrations of optically active water quality constituents. However, they cannot cope easily with shifts in reflectance features caused by multiple interactions between variable absorption and backscattering effects that typically occur in optically complex waters. We use continuous wavelet analysis to detect Chl-A features at various wavelengths and frequency scales. Using the wavelet decomposition, we build a 2-D correlation scalogram between in situ pond reflectance spectra and in situ Chl-A concentration. By isolating the most informative wavelet regions via thresholding, we could relate all five regions to known inherent optical properties. We select the optimal feature per region and compare them to three well-known narrow band ratio models. For this experimental application, the wavelet features outperform the NIR-red models, while fluorescence line height (FLH) yield comparable results. Because wavelets analyze the signal at different scales and synthesize information across bands, we hypothesize that the wavelet features are less sensitive to confounding factors, such as instrument noise, colored dissolved organic matter, and suspended matter.

    Original languageEnglish
    Article number6479237
    Pages (from-to)89-93
    Number of pages5
    JournalGeoscience and Remote Sensing Letters, IEEE
    Volume11
    Issue number1
    DOIs
    Publication statusPublished - 2014

    Keywords

    • Chlorophyll-A (chl-A)
    • frequency analysis
    • high spectral resolution remote sensing
    • optically complex waters
    • wavelets

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