A SWIR based algorithm to retrieve total suspended matter in extremely turbid waters
In ocean colour remote sensing, the use of Near Infra Red (NIR) spectral bands for the retrieval of Total Suspended Matter (TSM) concentration in turbid and highly turbid waters has proven to be successful. In extremely turbid waters (TSM>100mgL-1) however, these bands are less sensitive to incre...
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2015
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00344257_v168_n_p66_Knaeps http://hdl.handle.net/20.500.12110/paper_00344257_v168_n_p66_Knaeps |
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paper:paper_00344257_v168_n_p66_Knaeps2023-06-08T15:00:39Z A SWIR based algorithm to retrieve total suspended matter in extremely turbid waters Extremely turbid Short wave infra red Total suspended matter Water Absorption spectroscopy Algorithms Color Estuaries Infrared devices Oceanography Reflection Remote sensing Water Water absorption Airborne prism experiments Atmospheric correction algorithm Concentration maps Extremely turbid Ocean colour remote sensing Sensor noise level Short wave infrared Total suspended matter Signal to noise ratio algorithm atmospheric correction concentration (composition) data set estuarine environment near infrared ocean color remote sensing sensor signal-to-noise ratio spectral reflectance suspended load turbidity wavelength France Gironde Estuary Rio de la Plata Westerschelde In ocean colour remote sensing, the use of Near Infra Red (NIR) spectral bands for the retrieval of Total Suspended Matter (TSM) concentration in turbid and highly turbid waters has proven to be successful. In extremely turbid waters (TSM>100mgL-1) however, these bands are less sensitive to increases in TSM. Here it is proposed to use Short Wave Infra Red (SWIR) spectral bands between 1000 and 1300nm for these extreme cases. This SWIR spectral region is subdivided into two regions, SWIR-I (1000nm to 1200nm) and SWIR-II (1200nm to 1300nm) which correspond to local minima in the pure water absorption spectrum. For both spectral regions the water reflectance signal was measured in situ with an ASD spectrometer in three different extremely turbid estuarine sites: Scheldt (Belgium), Gironde (France), and Río de la Plata (Argentina), along with the TSM concentration. A measurable water reflectance was observed for all sites in SWIR-I, while in the SWIR-II region the signal was not significant compared to the Signal-to-Noise Ratio (SNR) of current Ocean Colour (OC) sensors. For the spectral band at 1020nm (present in Ocean and Land Colour Instrument - OLCI, onboard Sentinel-3) and at 1071nm, an empirical single band TSM algorithm is defined which is valid for both the Gironde and Scheldt estuarine sites. This means that a single algorithm can be applied for both sites without expensive recalibration. The relationship between TSM and SWIR reflectance at 1020 and 1071nm is linear and did not show any saturation for the concentrations measured here (up to 1400mgL-1), while saturation was observed for the NIR wavelengths, as expected. Hence, for extremely turbid waters it is advised to switch from NIR to SWIR-I wavelengths to estimate TSM concentration. This was demonstrated for an airborne hyperspectral dataset (Airborne Prism Experiment, APEX) from the Gironde estuary having several spectral bands in the SWIR-I. The empirical single band SWIR TSM algorithm was applied to the atmospherically corrected scene providing a TSM concentration map of the Gironde from mouth to more upstream with concentrations expected in this region ranging from a few to several hundreds mgL-1. These results, i.e. the existence of a single relationship for the Scheldt and Gironde, not showing any decrease of sensitivity, highlights the importance of having SWIR bands in future ocean colour sensors for studying extremely turbid rivers, coastal areas and estuaries in the world. A further implication of these results is that there is a TSM limit for application of atmospheric correction algorithms which assume zero SWIR marine reflectance. That limit is defined here as function of wavelength and sensor noise level. © 2015 Elsevier Inc. 2015 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00344257_v168_n_p66_Knaeps http://hdl.handle.net/20.500.12110/paper_00344257_v168_n_p66_Knaeps |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Extremely turbid Short wave infra red Total suspended matter Water Absorption spectroscopy Algorithms Color Estuaries Infrared devices Oceanography Reflection Remote sensing Water Water absorption Airborne prism experiments Atmospheric correction algorithm Concentration maps Extremely turbid Ocean colour remote sensing Sensor noise level Short wave infrared Total suspended matter Signal to noise ratio algorithm atmospheric correction concentration (composition) data set estuarine environment near infrared ocean color remote sensing sensor signal-to-noise ratio spectral reflectance suspended load turbidity wavelength France Gironde Estuary Rio de la Plata Westerschelde |
| spellingShingle |
Extremely turbid Short wave infra red Total suspended matter Water Absorption spectroscopy Algorithms Color Estuaries Infrared devices Oceanography Reflection Remote sensing Water Water absorption Airborne prism experiments Atmospheric correction algorithm Concentration maps Extremely turbid Ocean colour remote sensing Sensor noise level Short wave infrared Total suspended matter Signal to noise ratio algorithm atmospheric correction concentration (composition) data set estuarine environment near infrared ocean color remote sensing sensor signal-to-noise ratio spectral reflectance suspended load turbidity wavelength France Gironde Estuary Rio de la Plata Westerschelde A SWIR based algorithm to retrieve total suspended matter in extremely turbid waters |
| topic_facet |
Extremely turbid Short wave infra red Total suspended matter Water Absorption spectroscopy Algorithms Color Estuaries Infrared devices Oceanography Reflection Remote sensing Water Water absorption Airborne prism experiments Atmospheric correction algorithm Concentration maps Extremely turbid Ocean colour remote sensing Sensor noise level Short wave infrared Total suspended matter Signal to noise ratio algorithm atmospheric correction concentration (composition) data set estuarine environment near infrared ocean color remote sensing sensor signal-to-noise ratio spectral reflectance suspended load turbidity wavelength France Gironde Estuary Rio de la Plata Westerschelde |
| description |
In ocean colour remote sensing, the use of Near Infra Red (NIR) spectral bands for the retrieval of Total Suspended Matter (TSM) concentration in turbid and highly turbid waters has proven to be successful. In extremely turbid waters (TSM>100mgL-1) however, these bands are less sensitive to increases in TSM. Here it is proposed to use Short Wave Infra Red (SWIR) spectral bands between 1000 and 1300nm for these extreme cases. This SWIR spectral region is subdivided into two regions, SWIR-I (1000nm to 1200nm) and SWIR-II (1200nm to 1300nm) which correspond to local minima in the pure water absorption spectrum. For both spectral regions the water reflectance signal was measured in situ with an ASD spectrometer in three different extremely turbid estuarine sites: Scheldt (Belgium), Gironde (France), and Río de la Plata (Argentina), along with the TSM concentration. A measurable water reflectance was observed for all sites in SWIR-I, while in the SWIR-II region the signal was not significant compared to the Signal-to-Noise Ratio (SNR) of current Ocean Colour (OC) sensors. For the spectral band at 1020nm (present in Ocean and Land Colour Instrument - OLCI, onboard Sentinel-3) and at 1071nm, an empirical single band TSM algorithm is defined which is valid for both the Gironde and Scheldt estuarine sites. This means that a single algorithm can be applied for both sites without expensive recalibration. The relationship between TSM and SWIR reflectance at 1020 and 1071nm is linear and did not show any saturation for the concentrations measured here (up to 1400mgL-1), while saturation was observed for the NIR wavelengths, as expected. Hence, for extremely turbid waters it is advised to switch from NIR to SWIR-I wavelengths to estimate TSM concentration. This was demonstrated for an airborne hyperspectral dataset (Airborne Prism Experiment, APEX) from the Gironde estuary having several spectral bands in the SWIR-I. The empirical single band SWIR TSM algorithm was applied to the atmospherically corrected scene providing a TSM concentration map of the Gironde from mouth to more upstream with concentrations expected in this region ranging from a few to several hundreds mgL-1. These results, i.e. the existence of a single relationship for the Scheldt and Gironde, not showing any decrease of sensitivity, highlights the importance of having SWIR bands in future ocean colour sensors for studying extremely turbid rivers, coastal areas and estuaries in the world. A further implication of these results is that there is a TSM limit for application of atmospheric correction algorithms which assume zero SWIR marine reflectance. That limit is defined here as function of wavelength and sensor noise level. © 2015 Elsevier Inc. |
| title |
A SWIR based algorithm to retrieve total suspended matter in extremely turbid waters |
| title_short |
A SWIR based algorithm to retrieve total suspended matter in extremely turbid waters |
| title_full |
A SWIR based algorithm to retrieve total suspended matter in extremely turbid waters |
| title_fullStr |
A SWIR based algorithm to retrieve total suspended matter in extremely turbid waters |
| title_full_unstemmed |
A SWIR based algorithm to retrieve total suspended matter in extremely turbid waters |
| title_sort |
swir based algorithm to retrieve total suspended matter in extremely turbid waters |
| publishDate |
2015 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00344257_v168_n_p66_Knaeps http://hdl.handle.net/20.500.12110/paper_00344257_v168_n_p66_Knaeps |
| _version_ |
1768546199693950976 |