Performance evaluation of ocean color satellite models for deriving accurate chlorophyll estimates in the Gulf of Saint Lawrence
Author:
Montes-Hugo M.,Bouakba H.,Arnone R.
Abstract
Abstract. The understanding of phytoplankton dynamics in the Gulf of the Saint Lawrence (GSL) is critical for managing major fisheries off the Canadian East coast. In this study, the accuracy of two atmospheric correction techniques (NASA standard algorithm, SA, and Kuchinke's spectral optimization, KU) and three ocean color inversion models (Carder's empirical for SeaWiFS (Sea-viewing Wide Field-of-View Sensor), EC, Lee's quasi-analytical, QAA, and Garver- Siegel-Maritorena semi-empirical, GSM) for estimating the phytoplankton absorption coefficient at 443 nm (aph(443)) and the chlorophyll concentration (chl) in the GSL is examined. Each model was validated based on SeaWiFS images and shipboard measurements obtained during May of 2000 and April 2001. In general, aph(443) estimates derived from coupling KU and QAA models presented the smallest differences with respect to in situ determinations as measured by High Pressure liquid Chromatography measurements (median absolute bias per cruise up to 0.005, RMSE up to 0.013). A change on the inversion approach used for estimating aph(443) values produced up to 43.4% increase on prediction error as inferred from the median relative bias per cruise. Likewise, the impact of applying different atmospheric correction schemes was secondary and represented an additive error of up to 24.3%. By using SeaDAS (SeaWiFS Data Analysis System) default values for the optical cross section of phytoplankton (i.e., aph(443) = aph(443)/chl = 0.056 m2mg−1), the median relative bias of our chl estimates as derived from the most accurate spaceborne aph(443) retrievals and with respect to in situ determinations increased up to 29%.
Funder
Natural Sciences and Engineering Research Council of Canada
Publisher
Copernicus GmbH
Reference47 articles.
1. Ahmad, Z., Franz, B. A., McClain, C. R., Kwiatkowska, E. J., Werdell, J., and Shettle, E. P.: New aerosol models for the retrieval of aerosol optical thickness and normalized water-leaving radiances from the SeaWiFS and MODIS sensors overcoastal regions and open oceans, Appl. Optics, 49, 5545–5560, 2010. 2. Bailey, S. W., Franz, B. A., and Werdell, P. J.: Estimation of near-infrared water-leaving reflectance for satellite ocean color data processing, Opt. Express, 18, 7521–7527, 2010. 3. Balch, W. M., Eppley, R. W., Abbott, M. R., and Reid, F. M. H.: Bias in satellite-derived pigment measurement due to coccolithophores and dinoflagellates, J. Plankton Res., 11, 575–581, 1989. 4. Barnes, R. A., Holmes, A. W., Barnes, W. L., Esaias, W. E., McClain, C. R., and Svitek, T.: SeaWiFS prelaunch radiometric calibration and spectral characterization, in: SeaWiFS Technical Report Series, edited by: Hooker, S. B., Firestone, E., R., and Acker, J. G., NASA Technical Memorandum, NASA Goddard Space Flight Center, Greenbelt, Maryland, 104566, vol. 23, 55 pp., 1994. 5. Bricaud, A., Claustre, H., Ras, J., and Oubelkheir, K.: Natural variability of phytoplankton absorption in oceanic waters: influence of the size structure of algal populations, J. Geophys. Res., 109, 1–12, https://doi.org/10.1029/2004JC002419, 2004.
|
|