Abstract

The NASA Ocean Biology Processing Group's Calibration and Validation Team has analyzed the mission-long Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) on-orbit gain and detector calibration time series to verify that lunar calibrations, obtained at nonstandard gains and radiance ranges, are valid for Earth data collected at standard gains and typical ocean, cloud, and land radiances. For gain calibrations, a constant voltage injected into the postdetector electronics allows gain ratios to be computed for all four detectors in each band. The on-orbit lunar gain ratio time series show small drifts for the near infrared bands. These drifts are propagated into the ocean color data through the atmospheric correction parameter ϵ, which uses the 765/865  nm band ratio. An anomaly analysis of global mean normalized water-leaving radiances at 510  nm shows a small decrease over the mission, while an analysis of ϵ shows a corresponding increase. The drifts in the lunar time series for the 765 and 865   nm bands were corrected. An analysis of the revised water-leaving radiances at 510   nm shows the drift has been eliminated, while an analysis of ϵ shows a reduced drift. For detector calibrations, solar diffuser observations made by the individual detectors in each band allows the response of the detectors to be monitored separately. The mission-long time series of detector calibration data show that the variations in the response of the individual detectors are less than 0.5% over the mission for all bands except the 865  nm band, where the variations are less than 1%.

© 2007 Optical Society of America

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References

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  1. C. R. McClain, W. E. Esaias, W. Barnes, B. Guenther, D. Endres, S. B. Hooker, B. G. Mitchell, and R. Barnes, SeaWiFS Calibration and Validation Plan, NASA Tech. Memo. 104566 3, S. B. Hooker and E. R. Firestone, eds. (NASA Goddard Space Flight Center, Greenbelt, Maryland, 1992).
  2. R. A. Barnes, R. E. Eplee, Jr., F. S. Patt, and C. R. McClain, "Changes in the radiometric stability of SeaWiFS determined from lunar and solar-based measurements," Appl. Opt. 38, 4649-4664 (1999).
    [CrossRef]
  3. R. A. Barnes, R. E. Eplee, Jr., G. M. Schmidt, F. S. Patt, and C. R. McClain, "Calibration of SeaWiFS. I. Direct techniques," Appl. Opt. 40, 6682-6700 (2001).
    [CrossRef]
  4. R. E. Eplee, Jr., W. D. Robinson, S. W. Bailey, D. K. Clark, P. J. Werdell, M. Wang, R. A. Barnes, and C. R. McClain, "Calibration of SeaWiFS. II. Vicarious techniques," Appl. Opt. 40, 6701-6718 (2001).
    [CrossRef]
  5. B. A. Franz, S. W. Bailey, P. J. Werdell, and C. R. McClain, "Sensor-independent approach to the vicarious calibration of satellite ocean color radiometry," Appl. Opt. 46, 5068-5082 (2007).
    [CrossRef] [PubMed]
  6. R. E. Eplee, Jr., R. A. Barnes, and C. R. McClain, "SeaWiFS detector and gain calibrations: four years of on-orbit stability," in Earth Observing Systems VII, Proc. SPIE 4814, 282-288 (2002).
    [CrossRef]
  7. R. A. Barnes, A. W. Holmes, W. L. Barnes, W. E. Esaias, C. R. McClain, and T. Svitek, SeaWiFS Prelaunch Radiometric Calibration and Spectral Characterization, NASA Tech. Memo. 104566 23, S. B. Hooker, E. R. Firestone, and J. G. Acker, eds. (NASA Goddard Space Flight Center, Greenbelt, Maryland, 1994).
  8. R. E. Eplee, Jr., R. A. Barnes, F. S. Patt, G. Meister, and C. R. McClain, "SeaWiFS lunar calibration methodology after six years on orbit," in Earth Observing Systems IX, Proc. SPIE 5542, 1-13 (2004).
    [CrossRef]
  9. R. E. Eplee, Jr., F. S. Patt, G. Meister, B. A. Franz, S. W. Bailey, and C. R. McClain, "The on-orbit calibration of SeaWiFS: revised temperature and gain corrections," in Earth Observing Systems XII, Proc. SPIE 6677, 667713 (2007).
  10. B. C. Johnson, E. E. Early, R. E. Eplee, Jr., R. A. Barnes, and R. T. Caffrey, The 1997 Prelaunch Radiometric Calibration of SeaWiFS, NASA Tech. Memo. 1999-206892 4, S. B. Hooker and E. R. Firestone, eds. (NASA Goddard Space Flight Center, Greenbelt, Maryland, 1999).
  11. R. H. Woodward, R. A. Barnes, C. R. McClain, W. E. Esaias, W. L. Barnes, and A. T. Mecherikunnel, Modeling of the SeaWiFS Solar and Lunar Calibrations, NASA Tech. Memo. 104566 10, S. B. Hooker and E. R. Firestone, eds. (NASA Goddard Space Flight Center, Greenbelt, Maryland, 1993).
  12. B. A. Franz, P. J. Werdell, G. Meister, S. W. Bailey, R. E. Eplee, Jr., G. C. Feldman, E. Kwaitkowska, C. R. McClain, F. S. Patt, and D. Thomas, "The continuity of ocean color measurements from SeaWiFS to MODIS," in Earth Observing Systems X, Proc. SPIE 5882, 58820W (2005).
    [CrossRef]
  13. H. R. Gordon and M. Wang, "Retrieval of water-leaving radiance and aerosol optical thickness over the oceans with SeaWiFS--a preliminary algorithm," Appl. Opt. 33, 443-452 (1994).
    [CrossRef] [PubMed]
  14. M. Wang, K. D. Knobelspiesse, and C. R. McClain, "Study of the Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) aerosol optical property data over ocean in combination with the ocean color products," J. Geophys. Res. 110, D10S06 doi: (2005).
    [CrossRef]
  15. H. Fukushima, L.-P. Li, and K. Takeno, "Increasing trend in sub-micron aerosol particles over East Asian waters observed in 1998-2004 by Sea Wide Field-of-View Sensor (SeaWiFS)," in Remote Sensing of Clouds and the Atmosphere XI, Proc. SPIE 6362, 636205 (2006).
    [CrossRef]
  16. R. E. Eplee, Jr., F. S. Patt, R. A. Barnes, and C. R. McClain, "SeaWiFS long-term solar diffuser reflectance and sensor noise analyses," Appl. Opt. 46, 762-773 (2007).
    [CrossRef] [PubMed]
  17. R. A. Barnes and R. E. Eplee, Jr., "The SeaWiFS solar diffuser," in SeaWiFS Calibration Topics, Part 1, NASA Tech. Memo. 104566 39, S. B. Hooker and E. R. Firestone, eds. (NASA Goddard Space Flight Center, Greenbelt, Maryland, 1996), pp. 54-61.
  18. X. Xie, X. Xiong, D. Moyer, J. Sun, X. Liu, and W. Barnes, "Analysis of the MODIS solar diffuser screen vignetting function," in Earth Observing Systems X,Proc. SPIE 5882, 58820T (2005).
  19. G. Meister, F. S. Patt, X. Xiong, J. Sun, X. Xie, and C. R. McClain, "Residual correlations in the solar diffuser measurements of the MODIS Aqua ocean color bands to the sun yaw angle," in Earth Observing Systems X, Proc. SPIE 5882, 58820V (2005).
    [CrossRef]

2007 (3)

2006 (1)

H. Fukushima, L.-P. Li, and K. Takeno, "Increasing trend in sub-micron aerosol particles over East Asian waters observed in 1998-2004 by Sea Wide Field-of-View Sensor (SeaWiFS)," in Remote Sensing of Clouds and the Atmosphere XI, Proc. SPIE 6362, 636205 (2006).
[CrossRef]

2005 (4)

X. Xie, X. Xiong, D. Moyer, J. Sun, X. Liu, and W. Barnes, "Analysis of the MODIS solar diffuser screen vignetting function," in Earth Observing Systems X,Proc. SPIE 5882, 58820T (2005).

G. Meister, F. S. Patt, X. Xiong, J. Sun, X. Xie, and C. R. McClain, "Residual correlations in the solar diffuser measurements of the MODIS Aqua ocean color bands to the sun yaw angle," in Earth Observing Systems X, Proc. SPIE 5882, 58820V (2005).
[CrossRef]

B. A. Franz, P. J. Werdell, G. Meister, S. W. Bailey, R. E. Eplee, Jr., G. C. Feldman, E. Kwaitkowska, C. R. McClain, F. S. Patt, and D. Thomas, "The continuity of ocean color measurements from SeaWiFS to MODIS," in Earth Observing Systems X, Proc. SPIE 5882, 58820W (2005).
[CrossRef]

M. Wang, K. D. Knobelspiesse, and C. R. McClain, "Study of the Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) aerosol optical property data over ocean in combination with the ocean color products," J. Geophys. Res. 110, D10S06 doi: (2005).
[CrossRef]

2004 (1)

R. E. Eplee, Jr., R. A. Barnes, F. S. Patt, G. Meister, and C. R. McClain, "SeaWiFS lunar calibration methodology after six years on orbit," in Earth Observing Systems IX, Proc. SPIE 5542, 1-13 (2004).
[CrossRef]

2002 (1)

R. E. Eplee, Jr., R. A. Barnes, and C. R. McClain, "SeaWiFS detector and gain calibrations: four years of on-orbit stability," in Earth Observing Systems VII, Proc. SPIE 4814, 282-288 (2002).
[CrossRef]

2001 (2)

1999 (1)

1994 (1)

Appl. Opt. (6)

J. Geophys. Res. (1)

M. Wang, K. D. Knobelspiesse, and C. R. McClain, "Study of the Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) aerosol optical property data over ocean in combination with the ocean color products," J. Geophys. Res. 110, D10S06 doi: (2005).
[CrossRef]

Proc. SPIE (7)

H. Fukushima, L.-P. Li, and K. Takeno, "Increasing trend in sub-micron aerosol particles over East Asian waters observed in 1998-2004 by Sea Wide Field-of-View Sensor (SeaWiFS)," in Remote Sensing of Clouds and the Atmosphere XI, Proc. SPIE 6362, 636205 (2006).
[CrossRef]

X. Xie, X. Xiong, D. Moyer, J. Sun, X. Liu, and W. Barnes, "Analysis of the MODIS solar diffuser screen vignetting function," in Earth Observing Systems X,Proc. SPIE 5882, 58820T (2005).

G. Meister, F. S. Patt, X. Xiong, J. Sun, X. Xie, and C. R. McClain, "Residual correlations in the solar diffuser measurements of the MODIS Aqua ocean color bands to the sun yaw angle," in Earth Observing Systems X, Proc. SPIE 5882, 58820V (2005).
[CrossRef]

R. E. Eplee, Jr., R. A. Barnes, F. S. Patt, G. Meister, and C. R. McClain, "SeaWiFS lunar calibration methodology after six years on orbit," in Earth Observing Systems IX, Proc. SPIE 5542, 1-13 (2004).
[CrossRef]

R. E. Eplee, Jr., F. S. Patt, G. Meister, B. A. Franz, S. W. Bailey, and C. R. McClain, "The on-orbit calibration of SeaWiFS: revised temperature and gain corrections," in Earth Observing Systems XII, Proc. SPIE 6677, 667713 (2007).

R. E. Eplee, Jr., R. A. Barnes, and C. R. McClain, "SeaWiFS detector and gain calibrations: four years of on-orbit stability," in Earth Observing Systems VII, Proc. SPIE 4814, 282-288 (2002).
[CrossRef]

B. A. Franz, P. J. Werdell, G. Meister, S. W. Bailey, R. E. Eplee, Jr., G. C. Feldman, E. Kwaitkowska, C. R. McClain, F. S. Patt, and D. Thomas, "The continuity of ocean color measurements from SeaWiFS to MODIS," in Earth Observing Systems X, Proc. SPIE 5882, 58820W (2005).
[CrossRef]

Other (5)

C. R. McClain, W. E. Esaias, W. Barnes, B. Guenther, D. Endres, S. B. Hooker, B. G. Mitchell, and R. Barnes, SeaWiFS Calibration and Validation Plan, NASA Tech. Memo. 104566 3, S. B. Hooker and E. R. Firestone, eds. (NASA Goddard Space Flight Center, Greenbelt, Maryland, 1992).

R. A. Barnes, A. W. Holmes, W. L. Barnes, W. E. Esaias, C. R. McClain, and T. Svitek, SeaWiFS Prelaunch Radiometric Calibration and Spectral Characterization, NASA Tech. Memo. 104566 23, S. B. Hooker, E. R. Firestone, and J. G. Acker, eds. (NASA Goddard Space Flight Center, Greenbelt, Maryland, 1994).

B. C. Johnson, E. E. Early, R. E. Eplee, Jr., R. A. Barnes, and R. T. Caffrey, The 1997 Prelaunch Radiometric Calibration of SeaWiFS, NASA Tech. Memo. 1999-206892 4, S. B. Hooker and E. R. Firestone, eds. (NASA Goddard Space Flight Center, Greenbelt, Maryland, 1999).

R. H. Woodward, R. A. Barnes, C. R. McClain, W. E. Esaias, W. L. Barnes, and A. T. Mecherikunnel, Modeling of the SeaWiFS Solar and Lunar Calibrations, NASA Tech. Memo. 104566 10, S. B. Hooker and E. R. Firestone, eds. (NASA Goddard Space Flight Center, Greenbelt, Maryland, 1993).

R. A. Barnes and R. E. Eplee, Jr., "The SeaWiFS solar diffuser," in SeaWiFS Calibration Topics, Part 1, NASA Tech. Memo. 104566 39, S. B. Hooker and E. R. Firestone, eds. (NASA Goddard Space Flight Center, Greenbelt, Maryland, 1996), pp. 54-61.

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Figures (15)

Fig. 1
Fig. 1

Calibration curve for band 1 for the standard gain (Gain 1). (a) Measurements over the entire dynamic range of the band. (b) Measurements in the vicinity of the knees of the bilinear response. The radiance units are mW   cm 2 sr 1 μm 1 .

Fig. 2
Fig. 2

Band 1∕band 2 focal plane layout. The cloud (C) and ocean (O) detectors for each band are laid out as shown.

Fig. 3
Fig. 3

Lunar calibration time series. The radiometric corrections contained in the calibration table are the inverses of the fits. The vertical scale of the plot for bands 1–4 in (a) is different from the vertical scale of the plot for bands 5–8 in (b).

Fig. 4
Fig. 4

Band 2 calibration pulse time series. Band 2 shows the greatest change in the calibration pulse over the mission. The data are for the standard gain.

Fig. 5
Fig. 5

Gain ratio time series for band 1. The ratios are to the standard gain. The ocean detector ratios are plotted separately for GR2, GR3, and GR4. The cloud detector ratios are plotted together.

Fig. 6
Fig. 6

Ocean detector GR3 time series for all bands. The ratios are to the standard gain.

Fig. 7
Fig. 7

Gain ratio time series for the 4:1 TDI mode for all bands. The ratios are to the standard gain. The linear fits show the changes over the mission.

Fig. 8
Fig. 8

Level 3 time series anomaly plots. These plots show L WN for bands 1–4 ( 412   nm , 443   nm , 490   nm , 510   nm ). The linear fits show the trends over the mission. The radiance units are mW   cm 2 sr 1 μm 1 .

Fig. 9
Fig. 9

Level 3 time series anomaly plots. These plots show L WN for band 5 ( 555   nm ) , band 6 ( 670   nm ) , epsilon, and chlorophyll. The linear fits show the trends over the mission. The radiance units are mW   cm 2 sr 1 μm 1 , epsilon is dimensionless, and the chlorophyll units are m g m 3 .

Fig. 10
Fig. 10

Band 7∕band 8 ratio. The linear fit shows the change in the band ratio over the mission due to the GR3 drift.

Fig. 11
Fig. 11

GR3 time series for bands 7 and 8. The piecewise linear corrections to the lunar calibration time series are shown.

Fig. 12
Fig. 12

Level 3 time series anomaly plots after GR3 drift correction. These plots show L WN for bands 1–4 ( 412   nm , 443   nm , 490   nm , 510   nm ). The linear fits show the trends over the mission. The radiance units are mW   cm 2 sr 1 μm 1 .

Fig. 13
Fig. 13

Level 3 time series anomaly plots after GR3 drift correction. These plots show L WN for band 5 ( 555   nm ) , band 6 ( 670   nm ) , epsilon, and chlorophyll. The linear fits show the trends over the mission. The radiance units are mW   cm 2 sr 1 μm 1 , epsilon is dimensionless, and the chlorophyll units are mg   m 3 .

Fig. 14
Fig. 14

Detector calibration time series. For each detector, the time series are normalized to the first observation. The cloud detectors are detector 1 for the odd-numbered bands and detector 4 for the even-numbered bands.

Fig. 15
Fig. 15

Normalized detector calibration time series. For each band, the individual detector time series are normalized to the time series for the ensemble (the 4:1 TDI mode). The cloud detectors are shown in red.

Tables (8)

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Table 2 SeaWiFS Gains a

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Table 3 SeaWiFS Calibration Pulse

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Table 4 SeaWiFS Prelaunch Gain Ratios a

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Table 5 SeaWiFS Prelaunch Gain Ratios a

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Table 6 SeaWiFS On-Orbit Gain Ratios a

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Table 7 SeaWiFS Gain Ratios for the 4:1 TDI Mode a

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Table 8 Vicarious Gains for SeaWiFS a

Equations (4)

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G R X ( λ ) = C P ( G a i n X , λ ) C P ( G a i n 1 , λ ) .
ϵ ( λ , 865 ) = L a s ( λ ) F 0 ( 865 ) L a s ( 865 ) F 0 ( λ ) .
α ( λ ) = log e ( τ a ( λ ) τ a ( 865 ) ) / log e ( 865 λ ) .
R ( λ , T D I i ) = L ( λ , T D I i ) L ( λ , T D I 4 : 1 ) .

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