Abstract

Deployment platforms such as ships, towers or buoys may affect the accuracy of nearby radiometric measurements. Aiming at expanding the know-how on platform perturbations in above-water radiometric measurements, this study investigated the spectral impact of the Acqua Alta Oceanographic Tower (AAOT) on the remote-sensing reflectance RRS as a function of the distance d between the tower and the sensor footprint at the sea surface. This was accomplished by exploiting measurements performed with radiometers operated on deployment rigs extending beyond the AAOT superstructure with sensor viewing angle θ = 40° and relative azimuth ϕ = 90° between sensor and sun. AAOT perturbations were also investigated by increasing the reflectance of the tower through white sheets covering part of its superstructure. Results indicate a spectral dependence of perturbations in RRS more pronounced in the near infrared, significantly increasing with the tower reflectance and decreasing with the inverse square of the distance d. In particular, for distances approaching the platform height, AAOT perturbations are found to be generally well below 1% for measurements performed in the visible spectral region and exceed 2% beyond 800 nm. However, with identical measurement geometry, but increasing the AAOT reflectance through the white cover, perturbations approach 1% in the blue-green spectral region and exceed 2% beyond approximately 600 nm. These findings, yet derived from a distinct tower and for specific measurement conditions, raise awareness on spectral perturbations of deployment platforms in above-water radiometry and additionally provide practical elements for the implementation of measurement protocol allowing to constrain these perturbations below required thresholds.

© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

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Platform perturbations in above-water radiometry

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Appl. Opt. 43(21) 4254-4268 (2004)

References

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  1. S. B. Hooker and A. Morel, “Platform and environmental effects on above-water determinations of water-leaving radiances,” J. Atmospheric Ocean. Technol. 20, 187–205 (2003).
    [Crossref]
  2. S. B. Hooker and G. Zibordi, “Platform perturbations in above-water radiometry,” Appl. Opt. 44(4), 553–567 (2005).
    [Crossref] [PubMed]
  3. G. Zibordi, S. B. Hooker, J.-F. Berthon, and D. D’Alimonte, “Autonomous above-water radiance measurements from an offshore platform: a field assessment experiment,” J. Atmospheric Ocean. Technol. 19, 808–819 (2002).
    [Crossref]
  4. G. Zibordi, “Experimental evaluation of theoretical sea surface reflectance factors relevant to above-water radiometry,” Opt. Express 24(6), A446–A459 (2016).
    [Crossref] [PubMed]
  5. G. Zibordi and K. J. Voss, “In situ optical radiometry in the visible and near infrared,” in Optical Radiometry for Ocean Climate Measurements: Experimental Methods in the Physical Sciences, G. Zibordi, C. Donlon, and A. Parr, eds. (Elsevier Academic, 2014).
  6. M. Talone, G. Zibordi, I. Ansko, A. C. Banks, and J. Kuusk, “Stray light effects in above-water remote-sensing reflectance from hyperspectral radiometers,” Appl. Opt. 55(15), 3966–3977 (2016).
    [Crossref] [PubMed]
  7. S. B. Hooker, G. Lazin, G. Zibordi, and S. McLean, “An evaluation of above- and in-water methods for determining water-leaving radiances,” J. Atmospheric Ocean. Technol. 19, 486–515 (2002).
    [Crossref]
  8. C. D. Mobley, “Estimation of the remote-sensing reflectance from above-surface measurements,” Appl. Opt. 38(36), 7442–7455 (1999).
    [Crossref]
  9. G. Zibordi, B. Holben, I. Slutsker, D. Giles, D. D’Alimonte, F. Melín, J.-F. Berthon, D. Vandemark, H. Feng, G.E. Schuster, B. Fabbri, S. Kaitala, and J. Seppala, “AERONET-OC: a network for validation of ocean color primary products,” J. Atmospheric Ocean. Technol. 26, 1634–1651 (2009).
    [Crossref]
  10. A. Morel, D. Antoine, and B. Gentili, “Bidirectional reflectance of oceanic waters: accounting for Raman emission and varying particle scattering phase function,” Appl. Opt. 41(30), 6289–6306 (2002).
    [Crossref] [PubMed]
  11. G. Zibordi, J.-F. Berthon, F. Melín, D. D’Alimonte, and S. Kaitala, “Validation of satellite ocean color primary products at optically complex coastal sites: Northern Adriatic Sea, Northern Baltic Proper and Gulf of Finland,” Remote. Sens. Environ. 113, 2574–2591 (2009).
    [Crossref]
  12. G. Zibordi, F. Melín, J.-F. Berthon, and M. Talone, “In situ autonomous optical radiometry measurements for satellite ocean color validation in the Western Black Sea,” Ocean. Sci. 11, 275–286 (2015).
    [Crossref]
  13. G. Zibordi, J.-F. Berthon, F. Melín, and D. D’Alimonte, “Cross-site consistent in situ measurements for satellite ocean color applications: The BiOMaP radiometric dataset,” Remote. Sens. Environ. 115, 2104–2115 (2011).
    [Crossref]
  14. J.-P. Doyle and G. Zibordi, “Optical propagation within a three-dimensional shadowed atmosphere–ocean field: application to large deployment structures,” Appl. Opt. 41, 4283–4306 (2002).
    [Crossref] [PubMed]

2016 (2)

2015 (1)

G. Zibordi, F. Melín, J.-F. Berthon, and M. Talone, “In situ autonomous optical radiometry measurements for satellite ocean color validation in the Western Black Sea,” Ocean. Sci. 11, 275–286 (2015).
[Crossref]

2011 (1)

G. Zibordi, J.-F. Berthon, F. Melín, and D. D’Alimonte, “Cross-site consistent in situ measurements for satellite ocean color applications: The BiOMaP radiometric dataset,” Remote. Sens. Environ. 115, 2104–2115 (2011).
[Crossref]

2009 (2)

G. Zibordi, B. Holben, I. Slutsker, D. Giles, D. D’Alimonte, F. Melín, J.-F. Berthon, D. Vandemark, H. Feng, G.E. Schuster, B. Fabbri, S. Kaitala, and J. Seppala, “AERONET-OC: a network for validation of ocean color primary products,” J. Atmospheric Ocean. Technol. 26, 1634–1651 (2009).
[Crossref]

G. Zibordi, J.-F. Berthon, F. Melín, D. D’Alimonte, and S. Kaitala, “Validation of satellite ocean color primary products at optically complex coastal sites: Northern Adriatic Sea, Northern Baltic Proper and Gulf of Finland,” Remote. Sens. Environ. 113, 2574–2591 (2009).
[Crossref]

2005 (1)

2003 (1)

S. B. Hooker and A. Morel, “Platform and environmental effects on above-water determinations of water-leaving radiances,” J. Atmospheric Ocean. Technol. 20, 187–205 (2003).
[Crossref]

2002 (4)

G. Zibordi, S. B. Hooker, J.-F. Berthon, and D. D’Alimonte, “Autonomous above-water radiance measurements from an offshore platform: a field assessment experiment,” J. Atmospheric Ocean. Technol. 19, 808–819 (2002).
[Crossref]

S. B. Hooker, G. Lazin, G. Zibordi, and S. McLean, “An evaluation of above- and in-water methods for determining water-leaving radiances,” J. Atmospheric Ocean. Technol. 19, 486–515 (2002).
[Crossref]

J.-P. Doyle and G. Zibordi, “Optical propagation within a three-dimensional shadowed atmosphere–ocean field: application to large deployment structures,” Appl. Opt. 41, 4283–4306 (2002).
[Crossref] [PubMed]

A. Morel, D. Antoine, and B. Gentili, “Bidirectional reflectance of oceanic waters: accounting for Raman emission and varying particle scattering phase function,” Appl. Opt. 41(30), 6289–6306 (2002).
[Crossref] [PubMed]

1999 (1)

Ansko, I.

Antoine, D.

Banks, A. C.

Berthon, J.-F.

G. Zibordi, F. Melín, J.-F. Berthon, and M. Talone, “In situ autonomous optical radiometry measurements for satellite ocean color validation in the Western Black Sea,” Ocean. Sci. 11, 275–286 (2015).
[Crossref]

G. Zibordi, J.-F. Berthon, F. Melín, and D. D’Alimonte, “Cross-site consistent in situ measurements for satellite ocean color applications: The BiOMaP radiometric dataset,” Remote. Sens. Environ. 115, 2104–2115 (2011).
[Crossref]

G. Zibordi, J.-F. Berthon, F. Melín, D. D’Alimonte, and S. Kaitala, “Validation of satellite ocean color primary products at optically complex coastal sites: Northern Adriatic Sea, Northern Baltic Proper and Gulf of Finland,” Remote. Sens. Environ. 113, 2574–2591 (2009).
[Crossref]

G. Zibordi, B. Holben, I. Slutsker, D. Giles, D. D’Alimonte, F. Melín, J.-F. Berthon, D. Vandemark, H. Feng, G.E. Schuster, B. Fabbri, S. Kaitala, and J. Seppala, “AERONET-OC: a network for validation of ocean color primary products,” J. Atmospheric Ocean. Technol. 26, 1634–1651 (2009).
[Crossref]

G. Zibordi, S. B. Hooker, J.-F. Berthon, and D. D’Alimonte, “Autonomous above-water radiance measurements from an offshore platform: a field assessment experiment,” J. Atmospheric Ocean. Technol. 19, 808–819 (2002).
[Crossref]

D’Alimonte, D.

G. Zibordi, J.-F. Berthon, F. Melín, and D. D’Alimonte, “Cross-site consistent in situ measurements for satellite ocean color applications: The BiOMaP radiometric dataset,” Remote. Sens. Environ. 115, 2104–2115 (2011).
[Crossref]

G. Zibordi, B. Holben, I. Slutsker, D. Giles, D. D’Alimonte, F. Melín, J.-F. Berthon, D. Vandemark, H. Feng, G.E. Schuster, B. Fabbri, S. Kaitala, and J. Seppala, “AERONET-OC: a network for validation of ocean color primary products,” J. Atmospheric Ocean. Technol. 26, 1634–1651 (2009).
[Crossref]

G. Zibordi, J.-F. Berthon, F. Melín, D. D’Alimonte, and S. Kaitala, “Validation of satellite ocean color primary products at optically complex coastal sites: Northern Adriatic Sea, Northern Baltic Proper and Gulf of Finland,” Remote. Sens. Environ. 113, 2574–2591 (2009).
[Crossref]

G. Zibordi, S. B. Hooker, J.-F. Berthon, and D. D’Alimonte, “Autonomous above-water radiance measurements from an offshore platform: a field assessment experiment,” J. Atmospheric Ocean. Technol. 19, 808–819 (2002).
[Crossref]

Doyle, J.-P.

Fabbri, B.

G. Zibordi, B. Holben, I. Slutsker, D. Giles, D. D’Alimonte, F. Melín, J.-F. Berthon, D. Vandemark, H. Feng, G.E. Schuster, B. Fabbri, S. Kaitala, and J. Seppala, “AERONET-OC: a network for validation of ocean color primary products,” J. Atmospheric Ocean. Technol. 26, 1634–1651 (2009).
[Crossref]

Feng, H.

G. Zibordi, B. Holben, I. Slutsker, D. Giles, D. D’Alimonte, F. Melín, J.-F. Berthon, D. Vandemark, H. Feng, G.E. Schuster, B. Fabbri, S. Kaitala, and J. Seppala, “AERONET-OC: a network for validation of ocean color primary products,” J. Atmospheric Ocean. Technol. 26, 1634–1651 (2009).
[Crossref]

Gentili, B.

Giles, D.

G. Zibordi, B. Holben, I. Slutsker, D. Giles, D. D’Alimonte, F. Melín, J.-F. Berthon, D. Vandemark, H. Feng, G.E. Schuster, B. Fabbri, S. Kaitala, and J. Seppala, “AERONET-OC: a network for validation of ocean color primary products,” J. Atmospheric Ocean. Technol. 26, 1634–1651 (2009).
[Crossref]

Holben, B.

G. Zibordi, B. Holben, I. Slutsker, D. Giles, D. D’Alimonte, F. Melín, J.-F. Berthon, D. Vandemark, H. Feng, G.E. Schuster, B. Fabbri, S. Kaitala, and J. Seppala, “AERONET-OC: a network for validation of ocean color primary products,” J. Atmospheric Ocean. Technol. 26, 1634–1651 (2009).
[Crossref]

Hooker, S. B.

S. B. Hooker and G. Zibordi, “Platform perturbations in above-water radiometry,” Appl. Opt. 44(4), 553–567 (2005).
[Crossref] [PubMed]

S. B. Hooker and A. Morel, “Platform and environmental effects on above-water determinations of water-leaving radiances,” J. Atmospheric Ocean. Technol. 20, 187–205 (2003).
[Crossref]

G. Zibordi, S. B. Hooker, J.-F. Berthon, and D. D’Alimonte, “Autonomous above-water radiance measurements from an offshore platform: a field assessment experiment,” J. Atmospheric Ocean. Technol. 19, 808–819 (2002).
[Crossref]

S. B. Hooker, G. Lazin, G. Zibordi, and S. McLean, “An evaluation of above- and in-water methods for determining water-leaving radiances,” J. Atmospheric Ocean. Technol. 19, 486–515 (2002).
[Crossref]

Kaitala, S.

G. Zibordi, J.-F. Berthon, F. Melín, D. D’Alimonte, and S. Kaitala, “Validation of satellite ocean color primary products at optically complex coastal sites: Northern Adriatic Sea, Northern Baltic Proper and Gulf of Finland,” Remote. Sens. Environ. 113, 2574–2591 (2009).
[Crossref]

G. Zibordi, B. Holben, I. Slutsker, D. Giles, D. D’Alimonte, F. Melín, J.-F. Berthon, D. Vandemark, H. Feng, G.E. Schuster, B. Fabbri, S. Kaitala, and J. Seppala, “AERONET-OC: a network for validation of ocean color primary products,” J. Atmospheric Ocean. Technol. 26, 1634–1651 (2009).
[Crossref]

Kuusk, J.

Lazin, G.

S. B. Hooker, G. Lazin, G. Zibordi, and S. McLean, “An evaluation of above- and in-water methods for determining water-leaving radiances,” J. Atmospheric Ocean. Technol. 19, 486–515 (2002).
[Crossref]

McLean, S.

S. B. Hooker, G. Lazin, G. Zibordi, and S. McLean, “An evaluation of above- and in-water methods for determining water-leaving radiances,” J. Atmospheric Ocean. Technol. 19, 486–515 (2002).
[Crossref]

Melín, F.

G. Zibordi, F. Melín, J.-F. Berthon, and M. Talone, “In situ autonomous optical radiometry measurements for satellite ocean color validation in the Western Black Sea,” Ocean. Sci. 11, 275–286 (2015).
[Crossref]

G. Zibordi, J.-F. Berthon, F. Melín, and D. D’Alimonte, “Cross-site consistent in situ measurements for satellite ocean color applications: The BiOMaP radiometric dataset,” Remote. Sens. Environ. 115, 2104–2115 (2011).
[Crossref]

G. Zibordi, J.-F. Berthon, F. Melín, D. D’Alimonte, and S. Kaitala, “Validation of satellite ocean color primary products at optically complex coastal sites: Northern Adriatic Sea, Northern Baltic Proper and Gulf of Finland,” Remote. Sens. Environ. 113, 2574–2591 (2009).
[Crossref]

G. Zibordi, B. Holben, I. Slutsker, D. Giles, D. D’Alimonte, F. Melín, J.-F. Berthon, D. Vandemark, H. Feng, G.E. Schuster, B. Fabbri, S. Kaitala, and J. Seppala, “AERONET-OC: a network for validation of ocean color primary products,” J. Atmospheric Ocean. Technol. 26, 1634–1651 (2009).
[Crossref]

Mobley, C. D.

Morel, A.

S. B. Hooker and A. Morel, “Platform and environmental effects on above-water determinations of water-leaving radiances,” J. Atmospheric Ocean. Technol. 20, 187–205 (2003).
[Crossref]

A. Morel, D. Antoine, and B. Gentili, “Bidirectional reflectance of oceanic waters: accounting for Raman emission and varying particle scattering phase function,” Appl. Opt. 41(30), 6289–6306 (2002).
[Crossref] [PubMed]

Schuster, G.E.

G. Zibordi, B. Holben, I. Slutsker, D. Giles, D. D’Alimonte, F. Melín, J.-F. Berthon, D. Vandemark, H. Feng, G.E. Schuster, B. Fabbri, S. Kaitala, and J. Seppala, “AERONET-OC: a network for validation of ocean color primary products,” J. Atmospheric Ocean. Technol. 26, 1634–1651 (2009).
[Crossref]

Seppala, J.

G. Zibordi, B. Holben, I. Slutsker, D. Giles, D. D’Alimonte, F. Melín, J.-F. Berthon, D. Vandemark, H. Feng, G.E. Schuster, B. Fabbri, S. Kaitala, and J. Seppala, “AERONET-OC: a network for validation of ocean color primary products,” J. Atmospheric Ocean. Technol. 26, 1634–1651 (2009).
[Crossref]

Slutsker, I.

G. Zibordi, B. Holben, I. Slutsker, D. Giles, D. D’Alimonte, F. Melín, J.-F. Berthon, D. Vandemark, H. Feng, G.E. Schuster, B. Fabbri, S. Kaitala, and J. Seppala, “AERONET-OC: a network for validation of ocean color primary products,” J. Atmospheric Ocean. Technol. 26, 1634–1651 (2009).
[Crossref]

Talone, M.

M. Talone, G. Zibordi, I. Ansko, A. C. Banks, and J. Kuusk, “Stray light effects in above-water remote-sensing reflectance from hyperspectral radiometers,” Appl. Opt. 55(15), 3966–3977 (2016).
[Crossref] [PubMed]

G. Zibordi, F. Melín, J.-F. Berthon, and M. Talone, “In situ autonomous optical radiometry measurements for satellite ocean color validation in the Western Black Sea,” Ocean. Sci. 11, 275–286 (2015).
[Crossref]

Vandemark, D.

G. Zibordi, B. Holben, I. Slutsker, D. Giles, D. D’Alimonte, F. Melín, J.-F. Berthon, D. Vandemark, H. Feng, G.E. Schuster, B. Fabbri, S. Kaitala, and J. Seppala, “AERONET-OC: a network for validation of ocean color primary products,” J. Atmospheric Ocean. Technol. 26, 1634–1651 (2009).
[Crossref]

Voss, K. J.

G. Zibordi and K. J. Voss, “In situ optical radiometry in the visible and near infrared,” in Optical Radiometry for Ocean Climate Measurements: Experimental Methods in the Physical Sciences, G. Zibordi, C. Donlon, and A. Parr, eds. (Elsevier Academic, 2014).

Zibordi, G.

M. Talone, G. Zibordi, I. Ansko, A. C. Banks, and J. Kuusk, “Stray light effects in above-water remote-sensing reflectance from hyperspectral radiometers,” Appl. Opt. 55(15), 3966–3977 (2016).
[Crossref] [PubMed]

G. Zibordi, “Experimental evaluation of theoretical sea surface reflectance factors relevant to above-water radiometry,” Opt. Express 24(6), A446–A459 (2016).
[Crossref] [PubMed]

G. Zibordi, F. Melín, J.-F. Berthon, and M. Talone, “In situ autonomous optical radiometry measurements for satellite ocean color validation in the Western Black Sea,” Ocean. Sci. 11, 275–286 (2015).
[Crossref]

G. Zibordi, J.-F. Berthon, F. Melín, and D. D’Alimonte, “Cross-site consistent in situ measurements for satellite ocean color applications: The BiOMaP radiometric dataset,” Remote. Sens. Environ. 115, 2104–2115 (2011).
[Crossref]

G. Zibordi, J.-F. Berthon, F. Melín, D. D’Alimonte, and S. Kaitala, “Validation of satellite ocean color primary products at optically complex coastal sites: Northern Adriatic Sea, Northern Baltic Proper and Gulf of Finland,” Remote. Sens. Environ. 113, 2574–2591 (2009).
[Crossref]

G. Zibordi, B. Holben, I. Slutsker, D. Giles, D. D’Alimonte, F. Melín, J.-F. Berthon, D. Vandemark, H. Feng, G.E. Schuster, B. Fabbri, S. Kaitala, and J. Seppala, “AERONET-OC: a network for validation of ocean color primary products,” J. Atmospheric Ocean. Technol. 26, 1634–1651 (2009).
[Crossref]

S. B. Hooker and G. Zibordi, “Platform perturbations in above-water radiometry,” Appl. Opt. 44(4), 553–567 (2005).
[Crossref] [PubMed]

J.-P. Doyle and G. Zibordi, “Optical propagation within a three-dimensional shadowed atmosphere–ocean field: application to large deployment structures,” Appl. Opt. 41, 4283–4306 (2002).
[Crossref] [PubMed]

S. B. Hooker, G. Lazin, G. Zibordi, and S. McLean, “An evaluation of above- and in-water methods for determining water-leaving radiances,” J. Atmospheric Ocean. Technol. 19, 486–515 (2002).
[Crossref]

G. Zibordi, S. B. Hooker, J.-F. Berthon, and D. D’Alimonte, “Autonomous above-water radiance measurements from an offshore platform: a field assessment experiment,” J. Atmospheric Ocean. Technol. 19, 808–819 (2002).
[Crossref]

G. Zibordi and K. J. Voss, “In situ optical radiometry in the visible and near infrared,” in Optical Radiometry for Ocean Climate Measurements: Experimental Methods in the Physical Sciences, G. Zibordi, C. Donlon, and A. Parr, eds. (Elsevier Academic, 2014).

Appl. Opt. (5)

J. Atmospheric Ocean. Technol. (4)

S. B. Hooker and A. Morel, “Platform and environmental effects on above-water determinations of water-leaving radiances,” J. Atmospheric Ocean. Technol. 20, 187–205 (2003).
[Crossref]

G. Zibordi, B. Holben, I. Slutsker, D. Giles, D. D’Alimonte, F. Melín, J.-F. Berthon, D. Vandemark, H. Feng, G.E. Schuster, B. Fabbri, S. Kaitala, and J. Seppala, “AERONET-OC: a network for validation of ocean color primary products,” J. Atmospheric Ocean. Technol. 26, 1634–1651 (2009).
[Crossref]

S. B. Hooker, G. Lazin, G. Zibordi, and S. McLean, “An evaluation of above- and in-water methods for determining water-leaving radiances,” J. Atmospheric Ocean. Technol. 19, 486–515 (2002).
[Crossref]

G. Zibordi, S. B. Hooker, J.-F. Berthon, and D. D’Alimonte, “Autonomous above-water radiance measurements from an offshore platform: a field assessment experiment,” J. Atmospheric Ocean. Technol. 19, 808–819 (2002).
[Crossref]

Ocean. Sci. (1)

G. Zibordi, F. Melín, J.-F. Berthon, and M. Talone, “In situ autonomous optical radiometry measurements for satellite ocean color validation in the Western Black Sea,” Ocean. Sci. 11, 275–286 (2015).
[Crossref]

Opt. Express (1)

Remote. Sens. Environ. (2)

G. Zibordi, J.-F. Berthon, F. Melín, and D. D’Alimonte, “Cross-site consistent in situ measurements for satellite ocean color applications: The BiOMaP radiometric dataset,” Remote. Sens. Environ. 115, 2104–2115 (2011).
[Crossref]

G. Zibordi, J.-F. Berthon, F. Melín, D. D’Alimonte, and S. Kaitala, “Validation of satellite ocean color primary products at optically complex coastal sites: Northern Adriatic Sea, Northern Baltic Proper and Gulf of Finland,” Remote. Sens. Environ. 113, 2574–2591 (2009).
[Crossref]

Other (1)

G. Zibordi and K. J. Voss, “In situ optical radiometry in the visible and near infrared,” in Optical Radiometry for Ocean Climate Measurements: Experimental Methods in the Physical Sciences, G. Zibordi, C. Donlon, and A. Parr, eds. (Elsevier Academic, 2014).

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Figures (9)

Fig. 1
Fig. 1 Top, front, and side views of the measurement setup. HDS permits to horizontally deploy an above-water system up to 11 m away from the upper deck edge. Conversely, VDS allows to vertically deploy an above-water system between 2.2 m and 8.2 m atop the upper deck level.
Fig. 2
Fig. 2 Spatial distribution in Cartesian coordinates of the sensor footprint at the sea surface for the various measurements. Circles and triangles correspond to HDS and VDS measurements, respectively. Colors indicate the measurement distances d from the platform.
Fig. 3
Fig. 3 (a) Remote-sensing reflectance spectra RRS(d, λ) determined with VDS at the position V5 (average values and standard deviations are indicated by the thick black line and error bars, respectively). (b) Sun zenith and azimuth angles for the overall measurements performed with HDS (black circles) and VDS (red triangles).
Fig. 4
Fig. 4 Variation coefficients of RRS(d, λ) values (light gray curves) determined from the VDS measurements collected at the position V5. Average values and standard deviations are indicated by the thick black line and error bars, respectively.
Fig. 5
Fig. 5 Values of ψ(d, λ) spectrally averaged over the 840 – 890 nm interval (empty light gray circles), successively geometrically averaged at 1 m increments (filled black circles), and the related S(λ)/d2 fitting curve (thick solid line). The thin dashed lines indicate ±σ computed with data from individual measurements.
Fig. 6
Fig. 6 Averaged values of δRRS (d, λ) (circles) and the corresponding fitted curves S(λ)/d2 (solid lines) for different spectral intervals determined from HDS measurements. Averaged values of δRRS (d, λ) from VDS measurements are superimposed (triangles).
Fig. 7
Fig. 7 AAOT platform (a) without and (b) with the white cover used for the assessment of spectral perturbations in above-water radiometric data.
Fig. 8
Fig. 8 Averaged values of δRRS (d, λ) (squares) and the corresponding fitted curves S(λ)/d2 (solid lines) for different spectral intervals, as determined from HDS measurements performed with the platform covered by white sheets.
Fig. 9
Fig. 9 Minimum distance where δRRS (d, λ) is lower than either 1% (solid lines), 2% (dashed line) or 5% (dotted line), for a low- (blue) and a high- (red) reflectance platform.

Tables (1)

Tables Icon

Table 1 List of the HDS and VDS positions and related distances/heights, applied during each measurement sequence.

Equations (7)

Equations on this page are rendered with MathJax. Learn more.

L ^ i ( θ , Δ ϕ , θ 0 , λ , t ) = L i ( θ , Δ ϕ , θ 0 , λ , t ) × E d ( θ 0 , λ , t 0 ) / E d ( θ 0 , λ , t ) ,
L ^ T ( d , θ , Δ ϕ , θ 0 , λ , t ) = L T ( d , θ , Δ ϕ , θ 0 , λ , t ) × E d ( θ 0 , λ , t 0 ) / E d ( θ 0 , λ , t ) .
R rs ( d , θ , Δ ϕ , θ o , λ ) = L w ( d , θ , Δ ϕ , θ 0 , λ ) / E ¯ d ( θ 0 , λ ) ,
L w ( d , θ , Δ ϕ , θ 0 , λ ) = L ¯ T ( d , θ , Δ ϕ , θ 0 , λ ) ρ ( θ , Δ ϕ , θ 0 , W ) × L ¯ i ( θ , Δ ϕ , θ 0 , λ ) ,
R RS ( d , λ ) = R RS ( D , λ ) [ 1 + δ R RS ( d , λ ) ] ,
ψ ( d , λ 0 ) = [ r ( d , λ 0 ) r ( D , λ 0 ) ] / r ( D , λ 0 ) ,
r ( d , λ 0 ) = [ L ¯ T ( d , θ , Δ ϕ , θ 0 , λ 0 ) / L ¯ i ( θ , Δ ϕ , θ 0 , λ 0 ) ] / ρ ( θ , Δ ϕ , θ 0 , W ) .

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