G. De Carolis - Academia.edu (original) (raw)
Papers by G. De Carolis
European Journal of Remote Sensing, 2013
ABSTRACT Multi-sensor satellite data are used to assess cyanobacteria blooms in the Curonian Lago... more ABSTRACT Multi-sensor satellite data are used to assess cyanobacteria blooms in the Curonian Lagoon. The exploitation of SAR, in combination with optical data, is investigated to take full advantage from the all-weather, night/day SAR imaging capability. A dataset of images has been analyzed to: 1) study the effect of cyanobacteria on microwave signals; 2) assess the daily evolution of cyanobacteria bloom from multi-sensors data; and 3) evaluate the dependence of dynamics of blooms on winds. The results show a significant correlation (R2 > 0.8, p<0.001) between the X- and C-band Normalized Radar Cross Section (NRCS) attenuation and the NIR-Red band ratio Index, with the latter considered as a proxy for the presence of cyanobacteria blooms. A combined use of microwave and optical observations can improve the detection of cyanobacteria blooms and their dependency on wind action.
Geoscience and Remote Sensing IEEE International Symposium, 1995
CO.RI.S.T.A. (Consortium for Research on Advanced Remote Sensors), in collaboration with the Univ... more CO.RI.S.T.A. (Consortium for Research on Advanced Remote Sensors), in collaboration with the Universities of Naples and Bari (Italy), has been developing a set of C-band ARCs, deployed during several synthetic-aperture radar (SAR) campaigns (TOPSAR 1991, ERS-1 1992 and 1993). The acquired experience has led to the design and development of a new set of ARCs operating in L-, C- and
The knowledge of grease ice properties in the context of climate research programmes is of chief ... more The knowledge of grease ice properties in the context of climate research programmes is of chief interest to predict the formation, growth and evolution stages of sea ice in turbulent ocean waters. Wave dispersion and attenuation in grease ice artificially grown in wave tank facilities can be explained assuming the particles motion in a two-layer viscous fluid, the ice layer
The technique of extracting valid directional wave spectra from subscenes of ERS SAR imagery is n... more The technique of extracting valid directional wave spectra from subscenes of ERS SAR imagery is now well demonstrated. By tracking the peak of the spectrum and measuring the change in wave number of this component on entering ice, it is pos- sible to estimate ice cover thickness so long as an appropriate dispersion theory is employed. A recently developed model by Keller (1998), in which a frazil-pancake ice cover is treated as a layer of highly viscous fluid, offers a good description of wave dispersion and attenuation in pancake icefields. Using ERSU2 SAR imagery from the winter Antarctic ice edge of April 2000, we have developed and apply an inversion procedure. The procedure involves the estimation of the open ocean spectrum close to the ice edge from a SAR spectrum based on the wind sea parameterisation; then the ocean spectrum in frazil-pancake ice is retrieved by applying the attenuation rates predicted in the Keller model to each wave number composing the spectrum. The best ...
Journal of Emotional and Behavioral Disorders, 2001
ABSTRACT Over the past decade, synthetic aperture radar (SAR) sensors have demonstrated their abi... more ABSTRACT Over the past decade, synthetic aperture radar (SAR) sensors have demonstrated their ability to provide accurate wind speed and direction measurements in the ocean. Although SAR capability to image the sea surface at a suitable spatial resolution, SAR wind field retrieval in marine coastal areas still remains an open issue. The aim of this work is to assess the potential and limits of the Bayesian approach to the C-band NRCS SAR inversion problem for the retrieval of wind fields in marine coastal areas. A dataset of 139 SAR images gathered by the European ERS-2 and ENVISAT satellites during 2007 was analyzed to estimate the sea surface wind vectors over three selected coastal sites in the Mediterranean Sea, offshore Puglia region (Italy). The sites were instrumented to monitor marine and environmental parameters, including wind intensity and direction for further comparison with SAR wind estimations. Results discussed in this study show that the statistical approach in the retrieval of SAR wind speed can be applied in coastal areas with performances comparable with those obtained off-shore. In contrast, the SAR inversion procedure was not able to retrieve wind direction with the same accuracy. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.
Journal of Physical Oceanography, 2002
Icefields composed of frazil and pancake ice play important roles in both polar regions in winter... more Icefields composed of frazil and pancake ice play important roles in both polar regions in winter. During the early to midwinter period pancake ice is a major component of the Antarctic sea ice cover, while in the Arctic the Odden ice tongue in the Greenland Sea, associated with deep convection, is composed mainly of pancake ice. The retrieval of sea ice thickness by remote sensing is, in general, a very difficult task. In this paper the change in dispersion of ocean waves as they penetrate into pancake ice is considered so as to gain insight into its possible relationship with thickness. Spectral analysis of subscenes from ERS-2 (second European Remote Sensing Satellite) synthetic aperture radar (SAR) images yields the wavelength and direction of the principal spectral component both outside and inside the ice cover. There is a decrease of wavelength at the ice edge, as well as refraction toward the normal and a loss of amplitude. The analysis is complex because the true wave spectrum must be retrieved from the SAR spectrum, involving an inversion technique that requires a ''firstguess'' spectrum. This analysis technique is described, together with a newer cross-spectral technique and a discussion of the wave theories that predict the change in wavelength. Results are reported from two experiments in the Odden ice tongue, in 1993 and 1997, both of which involved surface truth measurements from ships and wave buoys. In the Antarctic, results are reported from imagery of the outer ice-edge zone of the Weddell Sea sector in midwinter (July) 1997.
Journal of Fluid Mechanics, 2005
Grease ice is an agglomeration of disc-shaped ice crystals, named frazil ice, which forms in turb... more Grease ice is an agglomeration of disc-shaped ice crystals, named frazil ice, which forms in turbulent waters of the Polar Oceans and in rivers as well. It has been recognized that the properties of grease ice to damp surface gravity waves could be explained in terms of the effective viscosity of the ice slurry. This paper is devoted to the study of the dynamics of a suspension of disc-shaped particles in a gravity wave field. For dilute suspensions, depending on the strength and frequency of the external wave flow, two orientation regimes of the particles are predicted: a preferential orientation regime with the particles rotating in coherent fashion with the wave field, and a random orientation regime in which the particles oscillate around their initial orientation while diffusing under the effect of Brownian motion. For both motion regimes, the effective viscosity has been derived as a function of the wave frequency, wave amplitude and aspect ratio of the particles. Model predictions have been compared with wave attenuation data in frazil ice layers grown in wave tanks.
Over the past decade, synthetic aperture radar (SAR) sensors have demonstrated their ability to p... more Over the past decade, synthetic aperture radar (SAR) sensors have demonstrated their ability to provide accurate wind speed and direction measurements in the ocean. Although SAR capability to image the sea surface at a suitable spatial resolution, SAR wind field retrieval in marine coastal areas still remains an open issue. The aim of this work is to assess the potential and limits of the Bayesian approach to the C-band NRCS SAR inversion problem for the retrieval of wind fields in marine coastal areas. A dataset of 139 SAR images gathered by the European ERS-2 and ENVISAT satellites during 2007 was analyzed to estimate the sea surface wind vectors over three selected coastal sites in the Mediterranean Sea, offshore Puglia region (Italy). The sites were instrumented to monitor marine and environmental parameters, including wind intensity and direction for further comparison with SAR wind estimations. Results discussed in this study show that the statistical approach in the retrieval of SAR wind speed can be applied in coastal areas with performances comparable with those obtained off-shore. In contrast, the SAR inversion procedure was not able to retrieve wind direction with the same accuracy.
SAR Image Analysis, Modeling, and Techniques VII, 2005
SAR spaceborne capability to detect marine oil spills through damping of wind-generated short gra... more SAR spaceborne capability to detect marine oil spills through damping of wind-generated short gravity-capillary waves has been extensively demonstrated during past years. In contrast, it has not yet been found the optimal use of optical/NIR imaging sensors for detection and monitoring of polluted areas. We propose the use of Modis images acquired in sun glint conditions to reveal smoothed regions
International Journal of Remote Sensing, 2013
International Journal of Remote Sensing, 2009
... Remote Sensing of Environment , 76: 4956. [CrossRef], [Web of Science ®], [CSA] View all ref... more ... Remote Sensing of Environment , 76: 4956. [CrossRef], [Web of Science ®], [CSA] View all references); Chust and Sagarminaga (20077. Chust, G. and Sagarminaga, Y. 2007. The multi-angle view of MISR detects oil slicks under sun glitter conditions. ...
The detection of marine oil slicks using satellite sun-glittered optical imagery has been recentl... more The detection of marine oil slicks using satellite sun-glittered optical imagery has been recently assessed. As the nature of the imaging mechanism involves the altered features of the wind-roughened oil-covered sea surface, it is expected that the radiation reflected from the oil-water system carries information about the physical properties of the floating oil layer. In this paper, we report an investigation on the capability to retrieve the average thickness of thin marine oil slicks by using the sun-glittered component of the solar radiation in the near-infrared (NIR) bands of MEdium Resolution Imaging Spectrometer Instrument (MERIS) and MODerate Resolution Imaging Spectroradiometer (MODIS) images. The developed procedure exploits the Cox and Munk model to compute sun glint reflectance at the sea surface level for both clean and oil polluted sea surface as well. It is assumed that the Fresnel reflection coefficient of the oil-water system carries the relevant optical dependence on oil layer thickness and oil type. The expected oil-water system reflectance is computed by taking into account the non-uniform spatial distribution of the oil volume. This is achieved by considering a pdf of oil thicknesses that matches the observations on controlled oil slicks already reported in the scientific literature. MERIS and MODIS images gathered during the Lebanon oil spill occurred on July and August 2006 were selected as case study. When available, colocated SAR imagery was also considered to corroborate NIRdetected oil slicks.
Advances in SAR …, 2006
A study aimed at retrieving sea surface wind fields of semi-enclosed basins from combined use of ... more A study aimed at retrieving sea surface wind fields of semi-enclosed basins from combined use of SAR imagery and a high resolution mesoscale numerical atmospheric model, is presented. Two consecutive ERS-2 SAR frames and a set of NOAA/AVHRR and ...
Quantitative analysis of multi-temporal SAR datasets requires accurate radiometric calibration. T... more Quantitative analysis of multi-temporal SAR datasets requires accurate radiometric calibration. This can usually be achieved by considering a number of multiplicative factors, to be applied to statistically-homogeneous areas on each image to be calibrated. We propose an automated procedure to easily obtain a relative radiometric calibration of a stack of an arbitrary number of ERS SAR images, all coregistered to
European Journal of Remote Sensing, 2013
ABSTRACT Multi-sensor satellite data are used to assess cyanobacteria blooms in the Curonian Lago... more ABSTRACT Multi-sensor satellite data are used to assess cyanobacteria blooms in the Curonian Lagoon. The exploitation of SAR, in combination with optical data, is investigated to take full advantage from the all-weather, night/day SAR imaging capability. A dataset of images has been analyzed to: 1) study the effect of cyanobacteria on microwave signals; 2) assess the daily evolution of cyanobacteria bloom from multi-sensors data; and 3) evaluate the dependence of dynamics of blooms on winds. The results show a significant correlation (R2 > 0.8, p<0.001) between the X- and C-band Normalized Radar Cross Section (NRCS) attenuation and the NIR-Red band ratio Index, with the latter considered as a proxy for the presence of cyanobacteria blooms. A combined use of microwave and optical observations can improve the detection of cyanobacteria blooms and their dependency on wind action.
Geoscience and Remote Sensing IEEE International Symposium, 1995
CO.RI.S.T.A. (Consortium for Research on Advanced Remote Sensors), in collaboration with the Univ... more CO.RI.S.T.A. (Consortium for Research on Advanced Remote Sensors), in collaboration with the Universities of Naples and Bari (Italy), has been developing a set of C-band ARCs, deployed during several synthetic-aperture radar (SAR) campaigns (TOPSAR 1991, ERS-1 1992 and 1993). The acquired experience has led to the design and development of a new set of ARCs operating in L-, C- and
The knowledge of grease ice properties in the context of climate research programmes is of chief ... more The knowledge of grease ice properties in the context of climate research programmes is of chief interest to predict the formation, growth and evolution stages of sea ice in turbulent ocean waters. Wave dispersion and attenuation in grease ice artificially grown in wave tank facilities can be explained assuming the particles motion in a two-layer viscous fluid, the ice layer
The technique of extracting valid directional wave spectra from subscenes of ERS SAR imagery is n... more The technique of extracting valid directional wave spectra from subscenes of ERS SAR imagery is now well demonstrated. By tracking the peak of the spectrum and measuring the change in wave number of this component on entering ice, it is pos- sible to estimate ice cover thickness so long as an appropriate dispersion theory is employed. A recently developed model by Keller (1998), in which a frazil-pancake ice cover is treated as a layer of highly viscous fluid, offers a good description of wave dispersion and attenuation in pancake icefields. Using ERSU2 SAR imagery from the winter Antarctic ice edge of April 2000, we have developed and apply an inversion procedure. The procedure involves the estimation of the open ocean spectrum close to the ice edge from a SAR spectrum based on the wind sea parameterisation; then the ocean spectrum in frazil-pancake ice is retrieved by applying the attenuation rates predicted in the Keller model to each wave number composing the spectrum. The best ...
Journal of Emotional and Behavioral Disorders, 2001
ABSTRACT Over the past decade, synthetic aperture radar (SAR) sensors have demonstrated their abi... more ABSTRACT Over the past decade, synthetic aperture radar (SAR) sensors have demonstrated their ability to provide accurate wind speed and direction measurements in the ocean. Although SAR capability to image the sea surface at a suitable spatial resolution, SAR wind field retrieval in marine coastal areas still remains an open issue. The aim of this work is to assess the potential and limits of the Bayesian approach to the C-band NRCS SAR inversion problem for the retrieval of wind fields in marine coastal areas. A dataset of 139 SAR images gathered by the European ERS-2 and ENVISAT satellites during 2007 was analyzed to estimate the sea surface wind vectors over three selected coastal sites in the Mediterranean Sea, offshore Puglia region (Italy). The sites were instrumented to monitor marine and environmental parameters, including wind intensity and direction for further comparison with SAR wind estimations. Results discussed in this study show that the statistical approach in the retrieval of SAR wind speed can be applied in coastal areas with performances comparable with those obtained off-shore. In contrast, the SAR inversion procedure was not able to retrieve wind direction with the same accuracy. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.
Journal of Physical Oceanography, 2002
Icefields composed of frazil and pancake ice play important roles in both polar regions in winter... more Icefields composed of frazil and pancake ice play important roles in both polar regions in winter. During the early to midwinter period pancake ice is a major component of the Antarctic sea ice cover, while in the Arctic the Odden ice tongue in the Greenland Sea, associated with deep convection, is composed mainly of pancake ice. The retrieval of sea ice thickness by remote sensing is, in general, a very difficult task. In this paper the change in dispersion of ocean waves as they penetrate into pancake ice is considered so as to gain insight into its possible relationship with thickness. Spectral analysis of subscenes from ERS-2 (second European Remote Sensing Satellite) synthetic aperture radar (SAR) images yields the wavelength and direction of the principal spectral component both outside and inside the ice cover. There is a decrease of wavelength at the ice edge, as well as refraction toward the normal and a loss of amplitude. The analysis is complex because the true wave spectrum must be retrieved from the SAR spectrum, involving an inversion technique that requires a ''firstguess'' spectrum. This analysis technique is described, together with a newer cross-spectral technique and a discussion of the wave theories that predict the change in wavelength. Results are reported from two experiments in the Odden ice tongue, in 1993 and 1997, both of which involved surface truth measurements from ships and wave buoys. In the Antarctic, results are reported from imagery of the outer ice-edge zone of the Weddell Sea sector in midwinter (July) 1997.
Journal of Fluid Mechanics, 2005
Grease ice is an agglomeration of disc-shaped ice crystals, named frazil ice, which forms in turb... more Grease ice is an agglomeration of disc-shaped ice crystals, named frazil ice, which forms in turbulent waters of the Polar Oceans and in rivers as well. It has been recognized that the properties of grease ice to damp surface gravity waves could be explained in terms of the effective viscosity of the ice slurry. This paper is devoted to the study of the dynamics of a suspension of disc-shaped particles in a gravity wave field. For dilute suspensions, depending on the strength and frequency of the external wave flow, two orientation regimes of the particles are predicted: a preferential orientation regime with the particles rotating in coherent fashion with the wave field, and a random orientation regime in which the particles oscillate around their initial orientation while diffusing under the effect of Brownian motion. For both motion regimes, the effective viscosity has been derived as a function of the wave frequency, wave amplitude and aspect ratio of the particles. Model predictions have been compared with wave attenuation data in frazil ice layers grown in wave tanks.
Over the past decade, synthetic aperture radar (SAR) sensors have demonstrated their ability to p... more Over the past decade, synthetic aperture radar (SAR) sensors have demonstrated their ability to provide accurate wind speed and direction measurements in the ocean. Although SAR capability to image the sea surface at a suitable spatial resolution, SAR wind field retrieval in marine coastal areas still remains an open issue. The aim of this work is to assess the potential and limits of the Bayesian approach to the C-band NRCS SAR inversion problem for the retrieval of wind fields in marine coastal areas. A dataset of 139 SAR images gathered by the European ERS-2 and ENVISAT satellites during 2007 was analyzed to estimate the sea surface wind vectors over three selected coastal sites in the Mediterranean Sea, offshore Puglia region (Italy). The sites were instrumented to monitor marine and environmental parameters, including wind intensity and direction for further comparison with SAR wind estimations. Results discussed in this study show that the statistical approach in the retrieval of SAR wind speed can be applied in coastal areas with performances comparable with those obtained off-shore. In contrast, the SAR inversion procedure was not able to retrieve wind direction with the same accuracy.
SAR Image Analysis, Modeling, and Techniques VII, 2005
SAR spaceborne capability to detect marine oil spills through damping of wind-generated short gra... more SAR spaceborne capability to detect marine oil spills through damping of wind-generated short gravity-capillary waves has been extensively demonstrated during past years. In contrast, it has not yet been found the optimal use of optical/NIR imaging sensors for detection and monitoring of polluted areas. We propose the use of Modis images acquired in sun glint conditions to reveal smoothed regions
International Journal of Remote Sensing, 2013
International Journal of Remote Sensing, 2009
... Remote Sensing of Environment , 76: 4956. [CrossRef], [Web of Science ®], [CSA] View all ref... more ... Remote Sensing of Environment , 76: 4956. [CrossRef], [Web of Science ®], [CSA] View all references); Chust and Sagarminaga (20077. Chust, G. and Sagarminaga, Y. 2007. The multi-angle view of MISR detects oil slicks under sun glitter conditions. ...
The detection of marine oil slicks using satellite sun-glittered optical imagery has been recentl... more The detection of marine oil slicks using satellite sun-glittered optical imagery has been recently assessed. As the nature of the imaging mechanism involves the altered features of the wind-roughened oil-covered sea surface, it is expected that the radiation reflected from the oil-water system carries information about the physical properties of the floating oil layer. In this paper, we report an investigation on the capability to retrieve the average thickness of thin marine oil slicks by using the sun-glittered component of the solar radiation in the near-infrared (NIR) bands of MEdium Resolution Imaging Spectrometer Instrument (MERIS) and MODerate Resolution Imaging Spectroradiometer (MODIS) images. The developed procedure exploits the Cox and Munk model to compute sun glint reflectance at the sea surface level for both clean and oil polluted sea surface as well. It is assumed that the Fresnel reflection coefficient of the oil-water system carries the relevant optical dependence on oil layer thickness and oil type. The expected oil-water system reflectance is computed by taking into account the non-uniform spatial distribution of the oil volume. This is achieved by considering a pdf of oil thicknesses that matches the observations on controlled oil slicks already reported in the scientific literature. MERIS and MODIS images gathered during the Lebanon oil spill occurred on July and August 2006 were selected as case study. When available, colocated SAR imagery was also considered to corroborate NIRdetected oil slicks.
Advances in SAR …, 2006
A study aimed at retrieving sea surface wind fields of semi-enclosed basins from combined use of ... more A study aimed at retrieving sea surface wind fields of semi-enclosed basins from combined use of SAR imagery and a high resolution mesoscale numerical atmospheric model, is presented. Two consecutive ERS-2 SAR frames and a set of NOAA/AVHRR and ...
Quantitative analysis of multi-temporal SAR datasets requires accurate radiometric calibration. T... more Quantitative analysis of multi-temporal SAR datasets requires accurate radiometric calibration. This can usually be achieved by considering a number of multiplicative factors, to be applied to statistically-homogeneous areas on each image to be calibrated. We propose an automated procedure to easily obtain a relative radiometric calibration of a stack of an arbitrary number of ERS SAR images, all coregistered to