Automated SWIR based empirical sun glint correction of Landsat 8-OLI data over coastal turbid water

Abstract

The optimal exploitation of the oceanic information provided by recent high spatial resolution sensors such as Landsat 8-OLI is strongly conditioned by the quality of the water reflectance signal retrieval. One main issue stands in the ability to correct water pixels for the contamination of the sun glint, which might induce a seasonal or permanent loss of data according to the latitude. The SWIR information now provided for the most recent high spatial resolution sensors was used for evaluating the sun glint level and correcting the radiative signal for its effect. This has been performed transposing historical empirical formalisms based on the NIR signal. An automated SWIR-based sun glint correction procedure was then developed using a 4-year OLI archive gathered over very turbid waters of French Guiana (227 scenes). This procedure allows the practical limitations associated with past similar empirical methods (sensitivity to water turbidity and manual image per image correction) to be overcome. While a satisfactory preservation of the information over sun glint free pixels was observed, comparison exercises based on in situ R rs data gathered in sun glint affected areas emphasize the relevance of the proposed methodology (correction by a factor of 14 of the averaged bias in the R rs values after removing sun glint effects). Current limitations in the applicability of this SWIR-based empirical automated method are mainly associated with the presence of high cloud coverage, thin clouds in the OLI scene or highly spatially variable marine or atmospheric signal (around 47%, 42% and 11%, respectively, of the total of 12% of failure over French Guiana OLI archive). The potential large applicability of the procedure developed in this work was eventually demonstrated over contrasted coastal environments.

Dynamics of the Estuarine Turbidity Maximum Zone from Landsat-8 Data: The Case of the Maroni River Estuary, French Guiana

“…This results in the loss of contaminated pixels over the river and estuary. To recover these contaminated pixels, the images were corrected for this effect using the method proposed by Abascal-Zorrilla et al [45].The method uses SWIR information to perform an automatic correction of this effect based on the assumption that the water-leaving radiance is negligible on this band. For application of a blind correction, several masks have to be defined, such as the land mask, the clear waters mask and the sun glint mask.…”

“…No external measurements are needed to perform the atmospheric correction using this software. The OLI dataset was processed with the ACOLITE SWIR processing using a fixed epsilon computed on the data prior to sun glint correction, as explained by Abascal-Zorrilla et al [45]. The ACOLITE atmospheric correction chain used in the framework of this study was validated for French Guiana [45] and R rs data were obtained for the study area.…”

The Advantages of Landsat 8-OLI-Derived Suspended Particulate Matter Maps for Monitoring the Subtidal Extension of Amazonian Coastal Mud Banks (French Guiana)

“…The low latitude of French Guiana (3 • 30-6 • 30 N) and the solar and viewing path geometry of OLI led to the presence of a quasi-permanent glint contamination over the Landsat 8-OLI images used within the framework of this study. As a consequence, the use of Landsat 8-OLI data is highly limited due to the loss of the pixels located towards the eastern part of the four scenes covering this coastal domain [32]. In this study, a historical method based on the use of NIR information for estimating the level of sun glint was applied in order to correct for this effect [33], taking advantage of the availability of SWIR information which is more adapted for applications related to very turbid waters such as those of French Guiana [32].…”

Correction of Sunglint Effects in High Spatial Resolution Hyperspectral Imagery Using SWIR or NIR Bands and Taking Account of Spectral Variation of Refractive Index of Water

“…Subsequently, this method was implemented into a version of an atmospheric correction algorithm for retrieving the water-leaving reflectance from the hyperspectral imaging data collected using the portable remote imaging spectrometer (PRISM) [10] during several airborne campaigns. Since 2011, many new developments on sunglint corrections have been reported [11][12][13][14][15]. For example, Zorrilla et al [11] described an automated SWIR-based empirical sunglint correction method for processing the Landsat 8 operational land imager (OLI) [16] data acquired over turbid coastal waters.…”

“…Since 2011, many new developments on sunglint corrections have been reported [11][12][13][14][15]. For example, Zorrilla et al [11] described an automated SWIR-based empirical sunglint correction method for processing the Landsat 8 operational land imager (OLI) [16] data acquired over turbid coastal waters. Hamel et al [13] presented a sunglint correction technique for the Sentinel-2 multispectral instrument (MSI) [17] imagery over inland and sea waters using SWIR bands.…”