Abstract

The intensity and location of Sun glint in two Medium Resolution Imaging Spectrometer (MERIS) images was modeled using a radiative transfer model that includes elevation features as well as the slope of the sea surface. The results are compared to estimates made using glint flagging and correction approaches used within standard atmospheric correction processing code. The model estimate gives a glint pattern with a similar width but lower peak level than any current method, or than that estimated by a radiative transfer model with surfaces that include slope but not height. The MERIS third reprocessing recently adopted a new slope statistics model for Sun glint correction; the results show that this model is an outlier with respect to both the elevation model and other slope statistics models and we recommend that its adoption should be reviewed.

© 2013 Optical Society of America

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References

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  1. C. Hu, X. Li, W. G. Pichel, and F. E. Muller-Karger, “Detection of natural oil slicks in the NW Gulf of Mexico using MODIS imagery,” Geophys. Res. Lett. 36, L01604 (2009).
    [CrossRef]
  2. M. Wang and S. Bailey, “Correction of Sun glint contamination on the SeaWiFS ocean and atmosphere products,” Appl. Opt. 40, 4790–4798 (2001).
    [CrossRef]
  3. L. Bourg, F. Montagner, V. Billat, and S. Belanger, “Sun glint flag algorithm,” MERIS ATBD 2.13, version 4.3 (7 July 2011), https://earth.esa.int/instruments/meris/atbd/ .
  4. C. Cox and W. Munk, “Measurement of the roughness of the sea surface from photographs of the Sun’s glitter,” J. Opt. Soc. Am. 44, 838–850 (1954).
    [CrossRef]
  5. C. Cox and W. Munk, “Statistics of the sea surface derived from Sun glitter,” J. Mar. Res. 13, 198–227 (1954).
  6. N. Ebuchi and S. Kizu, “Probability distribution of surface wave slope derived using Sun glitter images from geostationary meteorological satellite and surface vector winds from scatterometers,” J. Oceanogr. 58, 477–486 (2002).
    [CrossRef]
  7. F. Bréon and N. Henriot, “Spaceborne observations of ocean glint reflectance and modeling of wave slope distributions,” J. Geophys. Res. Oceans 111, C06005 (2006).
    [CrossRef]
  8. H. Zhang and M. Wang, “Evaluation of Sun glint models using MODIS measurements,” J. Quant. Spectrosc. Radiat. Transfer 111, 492–506 (2010).
    [CrossRef]
  9. F. Steinmetz, P. Deschamps, and D. Ramon, “Atmospheric correction in presence of Sun glint: application to MERIS,” Opt. Express 19, 9783–9800 (2011).
    [CrossRef]
  10. R. Doerffer, H. Schiller, J. Fischer, R. Preusker, and M. Bouvet, “The impact of Sun glint on the retrieval of water parameters and possibilities for the correction of MERIS scenes,” presented at 2nd MERIS/(A)ATSR User Workshop, ESA/ESRIN Frascati, Rome, Italy, 22–26 Sept. 2008.
  11. R. Doerffer, “Alternative atmospheric correction procedure for case 2 water remote sensing using MERIS,” MERIS ATBD 2.25, version 1.0 (2011), https://earth.esa.int/instruments/meris/atbd/ .
  12. D. Müller and H. Krasemann, Product validation and algorithm selection report (PVASR) part 1 atmospheric correction (ESA, 2012), www.esa-oceancolour-cci.org .
  13. C. D. Mobley and L. K. Sundman, Hydrolight 5 users’ guide (Sequoia, 2008), http://www.sequoiasci.com/products/hl-radiative.cmsx .
  14. S. Kay, J. Hedley, S. Lavender, and A. Nimmo-Smith, “Light transfer at the ocean surface modeled using high resolution sea surface realizations,” Opt. Express 19, 6493–6504 (2011).
    [CrossRef]
  15. F. Montagner, V. Billat, and S. Belanger, “Sun glint flag algorithm,” MERIS ATBD 2.13 (2003), https://earth.esa.int/instruments/meris/atbd/atbd_2_13.pdf .
  16. C. Mobley, Light and Water: Radiative Transfer in Natural Waters (Academic, 1994).
  17. J. Hedley, “PlanarRad User Manual,” http://www.planarrad.com .
  18. J. Hedley, “PlanarRad software,” (2011), http://fsf.nerc.ac.uk/resources/software/planarrad/planarrad.shtml .
  19. T. Elfouhaily, B. Chapron, K. Katsaros, and D. Vandemark, “A unified directional spectrum for long and short wind-driven waves,” J. Geophys. Res. Oceans 102, 15781–15796 (1997).
    [CrossRef]
  20. M. Heron, W. Skirving, and K. Michael, “Short-wave ocean wave slope models for use in remote sensing data analysis,” IEEE Trans. Geosci. Remote Sens. 44, 1962–1973 (2006).
    [CrossRef]
  21. B. Mayer and A. Kylling, “Technical note: the libRadtran software package for radiative transfer calculations—description and examples of use,” Atmos. Chem. Phys. 5, 1855–1877 (2005).
    [CrossRef]
  22. B. Mayer, A. Kylling, C. Emde, U. Hamann, and R. Buras, “libRadtran user’s guide for libRadtran version 1.7,” (2012), www.libradtran.org/doc/libRadtran.pdf .
  23. R. H. Grant, G. M. Heisler, and W. Gao, “Photosynthetically-active radiation: sky radiance distributions under clear and overcast conditions,” Agric. For. Meteorol. 82, 267–292 (1996).
    [CrossRef]
  24. H. Gordon and K. Voss, MODIS normalized water-leaving radiance algorithm theoretical basis document, ATBD-MOD 18 (NASA, 2004), http://modis.gsfc.nasa.gov/data/atbd/ocean_atbd.php .
  25. P. Koepke, “Effective reflectance of oceanic whitecaps,” Appl. Opt. 23, 1816–1824 (1984).
    [CrossRef]
  26. ACRI, “MERIS level 1 detailed processing model” (2006) http://earth.esa.int/pub/ESA_DOC/ENVISAT/MERIS/Meris_DPM_L1b_i8r0.pdf .

2011 (2)

2010 (1)

H. Zhang and M. Wang, “Evaluation of Sun glint models using MODIS measurements,” J. Quant. Spectrosc. Radiat. Transfer 111, 492–506 (2010).
[CrossRef]

2009 (1)

C. Hu, X. Li, W. G. Pichel, and F. E. Muller-Karger, “Detection of natural oil slicks in the NW Gulf of Mexico using MODIS imagery,” Geophys. Res. Lett. 36, L01604 (2009).
[CrossRef]

2006 (2)

F. Bréon and N. Henriot, “Spaceborne observations of ocean glint reflectance and modeling of wave slope distributions,” J. Geophys. Res. Oceans 111, C06005 (2006).
[CrossRef]

M. Heron, W. Skirving, and K. Michael, “Short-wave ocean wave slope models for use in remote sensing data analysis,” IEEE Trans. Geosci. Remote Sens. 44, 1962–1973 (2006).
[CrossRef]

2005 (1)

B. Mayer and A. Kylling, “Technical note: the libRadtran software package for radiative transfer calculations—description and examples of use,” Atmos. Chem. Phys. 5, 1855–1877 (2005).
[CrossRef]

2002 (1)

N. Ebuchi and S. Kizu, “Probability distribution of surface wave slope derived using Sun glitter images from geostationary meteorological satellite and surface vector winds from scatterometers,” J. Oceanogr. 58, 477–486 (2002).
[CrossRef]

2001 (1)

1997 (1)

T. Elfouhaily, B. Chapron, K. Katsaros, and D. Vandemark, “A unified directional spectrum for long and short wind-driven waves,” J. Geophys. Res. Oceans 102, 15781–15796 (1997).
[CrossRef]

1996 (1)

R. H. Grant, G. M. Heisler, and W. Gao, “Photosynthetically-active radiation: sky radiance distributions under clear and overcast conditions,” Agric. For. Meteorol. 82, 267–292 (1996).
[CrossRef]

1984 (1)

1954 (2)

C. Cox and W. Munk, “Measurement of the roughness of the sea surface from photographs of the Sun’s glitter,” J. Opt. Soc. Am. 44, 838–850 (1954).
[CrossRef]

C. Cox and W. Munk, “Statistics of the sea surface derived from Sun glitter,” J. Mar. Res. 13, 198–227 (1954).

Bailey, S.

Bouvet, M.

R. Doerffer, H. Schiller, J. Fischer, R. Preusker, and M. Bouvet, “The impact of Sun glint on the retrieval of water parameters and possibilities for the correction of MERIS scenes,” presented at 2nd MERIS/(A)ATSR User Workshop, ESA/ESRIN Frascati, Rome, Italy, 22–26 Sept. 2008.

Bréon, F.

F. Bréon and N. Henriot, “Spaceborne observations of ocean glint reflectance and modeling of wave slope distributions,” J. Geophys. Res. Oceans 111, C06005 (2006).
[CrossRef]

Chapron, B.

T. Elfouhaily, B. Chapron, K. Katsaros, and D. Vandemark, “A unified directional spectrum for long and short wind-driven waves,” J. Geophys. Res. Oceans 102, 15781–15796 (1997).
[CrossRef]

Cox, C.

C. Cox and W. Munk, “Measurement of the roughness of the sea surface from photographs of the Sun’s glitter,” J. Opt. Soc. Am. 44, 838–850 (1954).
[CrossRef]

C. Cox and W. Munk, “Statistics of the sea surface derived from Sun glitter,” J. Mar. Res. 13, 198–227 (1954).

Deschamps, P.

Doerffer, R.

R. Doerffer, H. Schiller, J. Fischer, R. Preusker, and M. Bouvet, “The impact of Sun glint on the retrieval of water parameters and possibilities for the correction of MERIS scenes,” presented at 2nd MERIS/(A)ATSR User Workshop, ESA/ESRIN Frascati, Rome, Italy, 22–26 Sept. 2008.

Ebuchi, N.

N. Ebuchi and S. Kizu, “Probability distribution of surface wave slope derived using Sun glitter images from geostationary meteorological satellite and surface vector winds from scatterometers,” J. Oceanogr. 58, 477–486 (2002).
[CrossRef]

Elfouhaily, T.

T. Elfouhaily, B. Chapron, K. Katsaros, and D. Vandemark, “A unified directional spectrum for long and short wind-driven waves,” J. Geophys. Res. Oceans 102, 15781–15796 (1997).
[CrossRef]

Fischer, J.

R. Doerffer, H. Schiller, J. Fischer, R. Preusker, and M. Bouvet, “The impact of Sun glint on the retrieval of water parameters and possibilities for the correction of MERIS scenes,” presented at 2nd MERIS/(A)ATSR User Workshop, ESA/ESRIN Frascati, Rome, Italy, 22–26 Sept. 2008.

Gao, W.

R. H. Grant, G. M. Heisler, and W. Gao, “Photosynthetically-active radiation: sky radiance distributions under clear and overcast conditions,” Agric. For. Meteorol. 82, 267–292 (1996).
[CrossRef]

Gordon, H.

H. Gordon and K. Voss, MODIS normalized water-leaving radiance algorithm theoretical basis document, ATBD-MOD 18 (NASA, 2004), http://modis.gsfc.nasa.gov/data/atbd/ocean_atbd.php .

Grant, R. H.

R. H. Grant, G. M. Heisler, and W. Gao, “Photosynthetically-active radiation: sky radiance distributions under clear and overcast conditions,” Agric. For. Meteorol. 82, 267–292 (1996).
[CrossRef]

Hedley, J.

Heisler, G. M.

R. H. Grant, G. M. Heisler, and W. Gao, “Photosynthetically-active radiation: sky radiance distributions under clear and overcast conditions,” Agric. For. Meteorol. 82, 267–292 (1996).
[CrossRef]

Henriot, N.

F. Bréon and N. Henriot, “Spaceborne observations of ocean glint reflectance and modeling of wave slope distributions,” J. Geophys. Res. Oceans 111, C06005 (2006).
[CrossRef]

Heron, M.

M. Heron, W. Skirving, and K. Michael, “Short-wave ocean wave slope models for use in remote sensing data analysis,” IEEE Trans. Geosci. Remote Sens. 44, 1962–1973 (2006).
[CrossRef]

Hu, C.

C. Hu, X. Li, W. G. Pichel, and F. E. Muller-Karger, “Detection of natural oil slicks in the NW Gulf of Mexico using MODIS imagery,” Geophys. Res. Lett. 36, L01604 (2009).
[CrossRef]

Katsaros, K.

T. Elfouhaily, B. Chapron, K. Katsaros, and D. Vandemark, “A unified directional spectrum for long and short wind-driven waves,” J. Geophys. Res. Oceans 102, 15781–15796 (1997).
[CrossRef]

Kay, S.

Kizu, S.

N. Ebuchi and S. Kizu, “Probability distribution of surface wave slope derived using Sun glitter images from geostationary meteorological satellite and surface vector winds from scatterometers,” J. Oceanogr. 58, 477–486 (2002).
[CrossRef]

Koepke, P.

Krasemann, H.

D. Müller and H. Krasemann, Product validation and algorithm selection report (PVASR) part 1 atmospheric correction (ESA, 2012), www.esa-oceancolour-cci.org .

Kylling, A.

B. Mayer and A. Kylling, “Technical note: the libRadtran software package for radiative transfer calculations—description and examples of use,” Atmos. Chem. Phys. 5, 1855–1877 (2005).
[CrossRef]

Lavender, S.

Li, X.

C. Hu, X. Li, W. G. Pichel, and F. E. Muller-Karger, “Detection of natural oil slicks in the NW Gulf of Mexico using MODIS imagery,” Geophys. Res. Lett. 36, L01604 (2009).
[CrossRef]

Mayer, B.

B. Mayer and A. Kylling, “Technical note: the libRadtran software package for radiative transfer calculations—description and examples of use,” Atmos. Chem. Phys. 5, 1855–1877 (2005).
[CrossRef]

Michael, K.

M. Heron, W. Skirving, and K. Michael, “Short-wave ocean wave slope models for use in remote sensing data analysis,” IEEE Trans. Geosci. Remote Sens. 44, 1962–1973 (2006).
[CrossRef]

Mobley, C.

C. Mobley, Light and Water: Radiative Transfer in Natural Waters (Academic, 1994).

Mobley, C. D.

C. D. Mobley and L. K. Sundman, Hydrolight 5 users’ guide (Sequoia, 2008), http://www.sequoiasci.com/products/hl-radiative.cmsx .

Müller, D.

D. Müller and H. Krasemann, Product validation and algorithm selection report (PVASR) part 1 atmospheric correction (ESA, 2012), www.esa-oceancolour-cci.org .

Muller-Karger, F. E.

C. Hu, X. Li, W. G. Pichel, and F. E. Muller-Karger, “Detection of natural oil slicks in the NW Gulf of Mexico using MODIS imagery,” Geophys. Res. Lett. 36, L01604 (2009).
[CrossRef]

Munk, W.

C. Cox and W. Munk, “Statistics of the sea surface derived from Sun glitter,” J. Mar. Res. 13, 198–227 (1954).

C. Cox and W. Munk, “Measurement of the roughness of the sea surface from photographs of the Sun’s glitter,” J. Opt. Soc. Am. 44, 838–850 (1954).
[CrossRef]

Nimmo-Smith, A.

Pichel, W. G.

C. Hu, X. Li, W. G. Pichel, and F. E. Muller-Karger, “Detection of natural oil slicks in the NW Gulf of Mexico using MODIS imagery,” Geophys. Res. Lett. 36, L01604 (2009).
[CrossRef]

Preusker, R.

R. Doerffer, H. Schiller, J. Fischer, R. Preusker, and M. Bouvet, “The impact of Sun glint on the retrieval of water parameters and possibilities for the correction of MERIS scenes,” presented at 2nd MERIS/(A)ATSR User Workshop, ESA/ESRIN Frascati, Rome, Italy, 22–26 Sept. 2008.

Ramon, D.

Schiller, H.

R. Doerffer, H. Schiller, J. Fischer, R. Preusker, and M. Bouvet, “The impact of Sun glint on the retrieval of water parameters and possibilities for the correction of MERIS scenes,” presented at 2nd MERIS/(A)ATSR User Workshop, ESA/ESRIN Frascati, Rome, Italy, 22–26 Sept. 2008.

Skirving, W.

M. Heron, W. Skirving, and K. Michael, “Short-wave ocean wave slope models for use in remote sensing data analysis,” IEEE Trans. Geosci. Remote Sens. 44, 1962–1973 (2006).
[CrossRef]

Steinmetz, F.

Sundman, L. K.

C. D. Mobley and L. K. Sundman, Hydrolight 5 users’ guide (Sequoia, 2008), http://www.sequoiasci.com/products/hl-radiative.cmsx .

Vandemark, D.

T. Elfouhaily, B. Chapron, K. Katsaros, and D. Vandemark, “A unified directional spectrum for long and short wind-driven waves,” J. Geophys. Res. Oceans 102, 15781–15796 (1997).
[CrossRef]

Voss, K.

H. Gordon and K. Voss, MODIS normalized water-leaving radiance algorithm theoretical basis document, ATBD-MOD 18 (NASA, 2004), http://modis.gsfc.nasa.gov/data/atbd/ocean_atbd.php .

Wang, M.

H. Zhang and M. Wang, “Evaluation of Sun glint models using MODIS measurements,” J. Quant. Spectrosc. Radiat. Transfer 111, 492–506 (2010).
[CrossRef]

M. Wang and S. Bailey, “Correction of Sun glint contamination on the SeaWiFS ocean and atmosphere products,” Appl. Opt. 40, 4790–4798 (2001).
[CrossRef]

Zhang, H.

H. Zhang and M. Wang, “Evaluation of Sun glint models using MODIS measurements,” J. Quant. Spectrosc. Radiat. Transfer 111, 492–506 (2010).
[CrossRef]

Agric. For. Meteorol. (1)

R. H. Grant, G. M. Heisler, and W. Gao, “Photosynthetically-active radiation: sky radiance distributions under clear and overcast conditions,” Agric. For. Meteorol. 82, 267–292 (1996).
[CrossRef]

Appl. Opt. (2)

Atmos. Chem. Phys. (1)

B. Mayer and A. Kylling, “Technical note: the libRadtran software package for radiative transfer calculations—description and examples of use,” Atmos. Chem. Phys. 5, 1855–1877 (2005).
[CrossRef]

Geophys. Res. Lett. (1)

C. Hu, X. Li, W. G. Pichel, and F. E. Muller-Karger, “Detection of natural oil slicks in the NW Gulf of Mexico using MODIS imagery,” Geophys. Res. Lett. 36, L01604 (2009).
[CrossRef]

IEEE Trans. Geosci. Remote Sens. (1)

M. Heron, W. Skirving, and K. Michael, “Short-wave ocean wave slope models for use in remote sensing data analysis,” IEEE Trans. Geosci. Remote Sens. 44, 1962–1973 (2006).
[CrossRef]

J. Geophys. Res. Oceans (2)

T. Elfouhaily, B. Chapron, K. Katsaros, and D. Vandemark, “A unified directional spectrum for long and short wind-driven waves,” J. Geophys. Res. Oceans 102, 15781–15796 (1997).
[CrossRef]

F. Bréon and N. Henriot, “Spaceborne observations of ocean glint reflectance and modeling of wave slope distributions,” J. Geophys. Res. Oceans 111, C06005 (2006).
[CrossRef]

J. Mar. Res. (1)

C. Cox and W. Munk, “Statistics of the sea surface derived from Sun glitter,” J. Mar. Res. 13, 198–227 (1954).

J. Oceanogr. (1)

N. Ebuchi and S. Kizu, “Probability distribution of surface wave slope derived using Sun glitter images from geostationary meteorological satellite and surface vector winds from scatterometers,” J. Oceanogr. 58, 477–486 (2002).
[CrossRef]

J. Opt. Soc. Am. (1)

J. Quant. Spectrosc. Radiat. Transfer (1)

H. Zhang and M. Wang, “Evaluation of Sun glint models using MODIS measurements,” J. Quant. Spectrosc. Radiat. Transfer 111, 492–506 (2010).
[CrossRef]

Opt. Express (2)

Other (12)

F. Montagner, V. Billat, and S. Belanger, “Sun glint flag algorithm,” MERIS ATBD 2.13 (2003), https://earth.esa.int/instruments/meris/atbd/atbd_2_13.pdf .

C. Mobley, Light and Water: Radiative Transfer in Natural Waters (Academic, 1994).

J. Hedley, “PlanarRad User Manual,” http://www.planarrad.com .

J. Hedley, “PlanarRad software,” (2011), http://fsf.nerc.ac.uk/resources/software/planarrad/planarrad.shtml .

R. Doerffer, H. Schiller, J. Fischer, R. Preusker, and M. Bouvet, “The impact of Sun glint on the retrieval of water parameters and possibilities for the correction of MERIS scenes,” presented at 2nd MERIS/(A)ATSR User Workshop, ESA/ESRIN Frascati, Rome, Italy, 22–26 Sept. 2008.

R. Doerffer, “Alternative atmospheric correction procedure for case 2 water remote sensing using MERIS,” MERIS ATBD 2.25, version 1.0 (2011), https://earth.esa.int/instruments/meris/atbd/ .

D. Müller and H. Krasemann, Product validation and algorithm selection report (PVASR) part 1 atmospheric correction (ESA, 2012), www.esa-oceancolour-cci.org .

C. D. Mobley and L. K. Sundman, Hydrolight 5 users’ guide (Sequoia, 2008), http://www.sequoiasci.com/products/hl-radiative.cmsx .

L. Bourg, F. Montagner, V. Billat, and S. Belanger, “Sun glint flag algorithm,” MERIS ATBD 2.13, version 4.3 (7 July 2011), https://earth.esa.int/instruments/meris/atbd/ .

B. Mayer, A. Kylling, C. Emde, U. Hamann, and R. Buras, “libRadtran user’s guide for libRadtran version 1.7,” (2012), www.libradtran.org/doc/libRadtran.pdf .

H. Gordon and K. Voss, MODIS normalized water-leaving radiance algorithm theoretical basis document, ATBD-MOD 18 (NASA, 2004), http://modis.gsfc.nasa.gov/data/atbd/ocean_atbd.php .

ACRI, “MERIS level 1 detailed processing model” (2006) http://earth.esa.int/pub/ESA_DOC/ENVISAT/MERIS/Meris_DPM_L1b_i8r0.pdf .

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Figures (8)

Fig. 1.
Fig. 1.

Diagram to illustrate the division of the sphere used in ray tracing. The lower half of the sphere is divided in the same way.

Fig. 2.
Fig. 2.

Parts of two MERIS images, showing the lines chosen for simulation. (a) and (c) Atlantic Ocean, 35 ° 26 20 W , 25 ° 6 52 S to 27 ° 26 28 W , 26 ° 46 5 S , 31 December 2003. (b) and (d) Mediterranean Sea, 13 ° 0 20 E , 35 ° 41 33 N to 22 ° 9 54 E , 33 ° 49 57 N , 31 July 2006. (a) and (b) show level 1 RGB images, (c) and (d) show level 2 images with the medium and high glint pixels flagged in the center and on the right of the image.

Fig. 3.
Fig. 3.

Level 1 radiance calculated by the model (solid curves) and reported for MERIS (dashed curves) for the two image lines shown in Fig. 2. The model values are the mean for 10 surfaces. Pixels flagged as cloud in the MERIS data have been omitted. The vertical lines show the edges of the MERIS medium and high glint regions, as in Figs. 2(c) and 2(d).

Fig. 4.
Fig. 4.

Glint reflectance at four wavelengths estimated by the elevation-based model and Sun glint reflectance (wavelength independent) calculated as in the MERIS Sun glint algorithm, for the two image lines shown in Fig. 2. The model values are the mean for 10 surfaces. The ingoing and outgoing quads for each pixel and the wind speed used to generate the surface realization are shown below the main plots. The vertical lines show the edges of the MERIS medium and high glint regions.

Fig. 5.
Fig. 5.

Glint reflectance at 443 nm estimated by the model using the elevation-based sea surfaces (Elmodel) and slope-statistics surfaces (CMmodel). In each case the central line shows the mean for 10 surfaces; the minimum and maximum are also shown. The smooth curves show the Sun glint reflectance calculated using the MERIS algorithm and the vertical lines show the edges of the medium and high glint regions.

Fig. 6.
Fig. 6.

Glint reflectance (wavelength independent) for the two lines in Fig. 2, calculated by the MERIS method using various parameter values. See the text for details of the different methods. The value estimated by the current model using elevation-based surfaces and CM slope-statistics surfaces is also shown. (a), (c) Atlantic image; (b), (d) Mediterranean image. (a), (b) The full image line; (c), (d) the low and medium glint regions enlarged. The vertical lines show the edges of the MERIS medium and high glint regions.

Fig. 7.
Fig. 7.

Modeled glint reflectance at 443 nm for the elevation-based model with standard, clear sky, illumination and for direct irradiance only, with all illumination coming from the quad containing the Sun. (a) Values for the Atlantic image, (b) values for the Mediterranean image, (c), (d) the lower glint regions of (a) and (b) enlarged. Results are the mean for 10 surfaces; the minimum and maximum values are also shown. The smooth curves show the Sun glint reflectance calculated by using the MERIS algorithm (second and third reprocessing), and the vertical lines show the edges of the MERIS medium and high glint regions.

Fig. 8.
Fig. 8.

Glint reflectance at 443 nm estimated by using the elevation-based model with standard and high angular resolution. Results are the mean for five surfaces; the minimum and maximum values are also shown. (a) Values for the Atlantic image and (b) for the Mediterranean. The wind speed was taken as 5 m s 1 for all pixels.

Tables (1)

Tables Icon

Table 1. Summary of Methods for Sun Glint Estimation Described in Subsections 2.A and 2.B

Equations (10)

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ρ g = π L g / E d ,
ρ glint = π L glint E cos θ s = ρ ( ω , λ ) p ( ξ , η ) 4 cos 4 β cos θ v cos θ s ,
σ w 2 = 0.00316 U ± 0.004 ,
σ c 2 = 0.003 + 0.00192 U ± 0.002 ,
σ w 2 = 0.0053 + 0.000671 U 10 ,
σ c 2 = 0.0048 + 0.00152 U 10 .
σ w 2 = 0.001 + 0.00316 U 10 ± 0.00005 ,
σ c 2 = 0.003 + 0.00185 U 10 ± 0.00005 .
σ w 2 = σ c 2 = 0.00246 U 10 .
σ w 2 = 0.00316 U 10 , σ c 2 = 0.00192 U 10 .

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