Abstract

Errors in measurements of sea-surface skin temperature (SSST) caused by inappropriate measurements of sky radiance are discussed; both model simulations and in situ data obtained in the Atlantic Ocean are used. These errors are typically caused by incorrect radiometer view geometry (pointing), temporal mismatches between the sea surface and atmospheric views, and the effect of wind on the sea surface. For clear-sky, overcast, or high-humidity atmospheric conditions, SSST is relatively insensitive (<0.1 K) to sky-pointing errors of ±10° and to temporal mismatches between the sea and sky views. In mixed-cloud conditions, SSST errors greater than ±0.25 K are possible as a result either of poor radiometer pointing or of a temporal mismatch between the sea and sky views. Sea-surface emissivity also changes with sea view pointing angle. Sea view pointing errors should remain below 5° for SSST errors of <0.1 K. We conclude that the clear-sky requirement of satellite infrared SSST observations means that sky-pointing errors are small when one is obtaining in situ SSST validation data at zenith angles of <40°. At zenith angles greater than this, large errors are possible in high-wind-speed conditions. We recommend that high-resolution inclinometer measurements always be used, together with regular alternating sea and sky views, and that the temporal mismatch between sea and sky views be as small as possible. These results have important implications for the development of operational autonomous instruments for determining SSST for the long-term validation of satellite SSST.

© 2000 Optical Society of America

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References

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    [CrossRef]
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    [CrossRef]
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1999 (2)

C. J. Donlon, T. J. Nightingale, T. Sheasby, J. Turner, I. S. Robinson, W. J. Emery, “Implications of the thermal skin temperature of the ocean at high wind speed,” Geophys. Res. Lett. 26, 2505–2508 (1999).
[CrossRef]

C. J. Donlon, T. J. Nightingale, L. Fielder, G. Fisher, D. Baldwin, I. S. Robinson, “A low cost blackbody for the calibration of sea going infrared radiometer systems,” J. Atmos. Oceanic Technol. 16, 1183–1197 (1999).
[CrossRef]

1997 (1)

1996 (2)

P. D. Watts, M. R. Allen, T. J. Nightingale, “Wind speed effects on sea surface emission and reflection for the along track scanning radiometer,” J. Atmos. Oceanic Technol. 13, 126–141 (1996).
[CrossRef]

J. E. Bertie, Z. D. Lan, “Infrared intensities of liquids. XX. The intensity of the OH stretching band of liquid water revisited, and the best current values of the optical constants of H2O(1) at 25 °C between 15,000 and 1 cm-1,” Appl. Spectrosc. 50, 1047–1057 (1996).
[CrossRef]

1995 (2)

C. R. Zeisse, “Radiance of the ocean horizon,” J. Opt. Soc. Am. 12, 2022–2030 (1995).
[CrossRef]

K. A. Van Scoy, K. P. Morris, J. E. Robertson, A. J. Watson, “Thermal skin effect and the air-sea flux of carbon dioxide: a seasonal high-resolution estimate,” Global Biogeochem. Cycles 9, 253–262 (1995).
[CrossRef]

1988 (1)

K. Masuda, T. Takashima, Y. Takayama, “Emissivity of pure and sea waters for the model sea surface in the infrared window regions,” Remote Sens. Environ. 24, 313–329 (1988).
[CrossRef]

1977 (1)

M. R. Querry, W. E. Holland, R. C. Waring, L. M. Earls, M. D. Querry, “Relative reflectance and complex refractive index in the infrared for saline environmental waters,” J. Geophys. Res. 82, 1425–1433 (1977).
[CrossRef]

1954 (1)

Allen, M. R.

P. D. Watts, M. R. Allen, T. J. Nightingale, “Wind speed effects on sea surface emission and reflection for the along track scanning radiometer,” J. Atmos. Oceanic Technol. 13, 126–141 (1996).
[CrossRef]

Bakan, S.

L. Fiedler, S. Bakan, “Interferometric measurements of sea surface temperature and emissivity,” (Max-Plank-Institut für Meteorologie, Hamburg, Germany, 1997).

Baldwin, D.

C. J. Donlon, T. J. Nightingale, L. Fielder, G. Fisher, D. Baldwin, I. S. Robinson, “A low cost blackbody for the calibration of sea going infrared radiometer systems,” J. Atmos. Oceanic Technol. 16, 1183–1197 (1999).
[CrossRef]

Bertie, J. E.

Cox, C.

Donlon, C. J.

C. J. Donlon, T. J. Nightingale, L. Fielder, G. Fisher, D. Baldwin, I. S. Robinson, “A low cost blackbody for the calibration of sea going infrared radiometer systems,” J. Atmos. Oceanic Technol. 16, 1183–1197 (1999).
[CrossRef]

C. J. Donlon, T. J. Nightingale, T. Sheasby, J. Turner, I. S. Robinson, W. J. Emery, “Implications of the thermal skin temperature of the ocean at high wind speed,” Geophys. Res. Lett. 26, 2505–2508 (1999).
[CrossRef]

Earls, L. M.

M. R. Querry, W. E. Holland, R. C. Waring, L. M. Earls, M. D. Querry, “Relative reflectance and complex refractive index in the infrared for saline environmental waters,” J. Geophys. Res. 82, 1425–1433 (1977).
[CrossRef]

Emery, W. J.

C. J. Donlon, T. J. Nightingale, T. Sheasby, J. Turner, I. S. Robinson, W. J. Emery, “Implications of the thermal skin temperature of the ocean at high wind speed,” Geophys. Res. Lett. 26, 2505–2508 (1999).
[CrossRef]

Fiedler, L.

L. Fiedler, S. Bakan, “Interferometric measurements of sea surface temperature and emissivity,” (Max-Plank-Institut für Meteorologie, Hamburg, Germany, 1997).

Fielder, L.

C. J. Donlon, T. J. Nightingale, L. Fielder, G. Fisher, D. Baldwin, I. S. Robinson, “A low cost blackbody for the calibration of sea going infrared radiometer systems,” J. Atmos. Oceanic Technol. 16, 1183–1197 (1999).
[CrossRef]

Fisher, G.

C. J. Donlon, T. J. Nightingale, L. Fielder, G. Fisher, D. Baldwin, I. S. Robinson, “A low cost blackbody for the calibration of sea going infrared radiometer systems,” J. Atmos. Oceanic Technol. 16, 1183–1197 (1999).
[CrossRef]

Grassl, H.

H. Grassl, H. Hinzpeter, “The cool skin of the ocean,” World Meterological Organisation Global Atmospheric Radiation Program (GARP) Atlantic Tropical Experiment (GATE) Rep. (British National Oceanographic Library, Southampton, UK, 1975), pp. 229–236.

Hinzpeter, H.

H. Grassl, H. Hinzpeter, “The cool skin of the ocean,” World Meterological Organisation Global Atmospheric Radiation Program (GARP) Atlantic Tropical Experiment (GATE) Rep. (British National Oceanographic Library, Southampton, UK, 1975), pp. 229–236.

Holland, W. E.

M. R. Querry, W. E. Holland, R. C. Waring, L. M. Earls, M. D. Querry, “Relative reflectance and complex refractive index in the infrared for saline environmental waters,” J. Geophys. Res. 82, 1425–1433 (1977).
[CrossRef]

Lan, Z. D.

Masuda, K.

K. Masuda, T. Takashima, Y. Takayama, “Emissivity of pure and sea waters for the model sea surface in the infrared window regions,” Remote Sens. Environ. 24, 313–329 (1988).
[CrossRef]

Monk, W.

Morris, K. P.

K. A. Van Scoy, K. P. Morris, J. E. Robertson, A. J. Watson, “Thermal skin effect and the air-sea flux of carbon dioxide: a seasonal high-resolution estimate,” Global Biogeochem. Cycles 9, 253–262 (1995).
[CrossRef]

Nightingale, T. J.

C. J. Donlon, T. J. Nightingale, L. Fielder, G. Fisher, D. Baldwin, I. S. Robinson, “A low cost blackbody for the calibration of sea going infrared radiometer systems,” J. Atmos. Oceanic Technol. 16, 1183–1197 (1999).
[CrossRef]

C. J. Donlon, T. J. Nightingale, T. Sheasby, J. Turner, I. S. Robinson, W. J. Emery, “Implications of the thermal skin temperature of the ocean at high wind speed,” Geophys. Res. Lett. 26, 2505–2508 (1999).
[CrossRef]

P. D. Watts, M. R. Allen, T. J. Nightingale, “Wind speed effects on sea surface emission and reflection for the along track scanning radiometer,” J. Atmos. Oceanic Technol. 13, 126–141 (1996).
[CrossRef]

Querry, M. D.

M. R. Querry, W. E. Holland, R. C. Waring, L. M. Earls, M. D. Querry, “Relative reflectance and complex refractive index in the infrared for saline environmental waters,” J. Geophys. Res. 82, 1425–1433 (1977).
[CrossRef]

Querry, M. R.

M. R. Querry, W. E. Holland, R. C. Waring, L. M. Earls, M. D. Querry, “Relative reflectance and complex refractive index in the infrared for saline environmental waters,” J. Geophys. Res. 82, 1425–1433 (1977).
[CrossRef]

Robertson, J. E.

K. A. Van Scoy, K. P. Morris, J. E. Robertson, A. J. Watson, “Thermal skin effect and the air-sea flux of carbon dioxide: a seasonal high-resolution estimate,” Global Biogeochem. Cycles 9, 253–262 (1995).
[CrossRef]

Robinson, I. S.

C. J. Donlon, T. J. Nightingale, L. Fielder, G. Fisher, D. Baldwin, I. S. Robinson, “A low cost blackbody for the calibration of sea going infrared radiometer systems,” J. Atmos. Oceanic Technol. 16, 1183–1197 (1999).
[CrossRef]

C. J. Donlon, T. J. Nightingale, T. Sheasby, J. Turner, I. S. Robinson, W. J. Emery, “Implications of the thermal skin temperature of the ocean at high wind speed,” Geophys. Res. Lett. 26, 2505–2508 (1999).
[CrossRef]

Sheasby, T.

C. J. Donlon, T. J. Nightingale, T. Sheasby, J. Turner, I. S. Robinson, W. J. Emery, “Implications of the thermal skin temperature of the ocean at high wind speed,” Geophys. Res. Lett. 26, 2505–2508 (1999).
[CrossRef]

Smith, W. L.

Takashima, T.

K. Masuda, T. Takashima, Y. Takayama, “Emissivity of pure and sea waters for the model sea surface in the infrared window regions,” Remote Sens. Environ. 24, 313–329 (1988).
[CrossRef]

Takayama, Y.

K. Masuda, T. Takashima, Y. Takayama, “Emissivity of pure and sea waters for the model sea surface in the infrared window regions,” Remote Sens. Environ. 24, 313–329 (1988).
[CrossRef]

Turner, J.

C. J. Donlon, T. J. Nightingale, T. Sheasby, J. Turner, I. S. Robinson, W. J. Emery, “Implications of the thermal skin temperature of the ocean at high wind speed,” Geophys. Res. Lett. 26, 2505–2508 (1999).
[CrossRef]

Van Scoy, K. A.

K. A. Van Scoy, K. P. Morris, J. E. Robertson, A. J. Watson, “Thermal skin effect and the air-sea flux of carbon dioxide: a seasonal high-resolution estimate,” Global Biogeochem. Cycles 9, 253–262 (1995).
[CrossRef]

Waring, R. C.

M. R. Querry, W. E. Holland, R. C. Waring, L. M. Earls, M. D. Querry, “Relative reflectance and complex refractive index in the infrared for saline environmental waters,” J. Geophys. Res. 82, 1425–1433 (1977).
[CrossRef]

Watson, A. J.

K. A. Van Scoy, K. P. Morris, J. E. Robertson, A. J. Watson, “Thermal skin effect and the air-sea flux of carbon dioxide: a seasonal high-resolution estimate,” Global Biogeochem. Cycles 9, 253–262 (1995).
[CrossRef]

Watts, P. D.

P. D. Watts, M. R. Allen, T. J. Nightingale, “Wind speed effects on sea surface emission and reflection for the along track scanning radiometer,” J. Atmos. Oceanic Technol. 13, 126–141 (1996).
[CrossRef]

Wu, X. Q.

Zappa, C. J.

C. J. Zappa, “Test of OPHIR calibration bucket using infrared imagery,” (University of Washington, Seattle, Wash., 1995).

Zeisse, C. R.

C. R. Zeisse, “Radiance of the ocean horizon,” J. Opt. Soc. Am. 12, 2022–2030 (1995).
[CrossRef]

Appl. Opt. (1)

Appl. Spectrosc. (1)

Geophys. Res. Lett. (1)

C. J. Donlon, T. J. Nightingale, T. Sheasby, J. Turner, I. S. Robinson, W. J. Emery, “Implications of the thermal skin temperature of the ocean at high wind speed,” Geophys. Res. Lett. 26, 2505–2508 (1999).
[CrossRef]

Global Biogeochem. Cycles (1)

K. A. Van Scoy, K. P. Morris, J. E. Robertson, A. J. Watson, “Thermal skin effect and the air-sea flux of carbon dioxide: a seasonal high-resolution estimate,” Global Biogeochem. Cycles 9, 253–262 (1995).
[CrossRef]

J. Atmos. Oceanic Technol. (2)

C. J. Donlon, T. J. Nightingale, L. Fielder, G. Fisher, D. Baldwin, I. S. Robinson, “A low cost blackbody for the calibration of sea going infrared radiometer systems,” J. Atmos. Oceanic Technol. 16, 1183–1197 (1999).
[CrossRef]

P. D. Watts, M. R. Allen, T. J. Nightingale, “Wind speed effects on sea surface emission and reflection for the along track scanning radiometer,” J. Atmos. Oceanic Technol. 13, 126–141 (1996).
[CrossRef]

J. Geophys. Res. (1)

M. R. Querry, W. E. Holland, R. C. Waring, L. M. Earls, M. D. Querry, “Relative reflectance and complex refractive index in the infrared for saline environmental waters,” J. Geophys. Res. 82, 1425–1433 (1977).
[CrossRef]

J. Opt. Soc. Am. (2)

Remote Sens. Environ. (1)

K. Masuda, T. Takashima, Y. Takayama, “Emissivity of pure and sea waters for the model sea surface in the infrared window regions,” Remote Sens. Environ. 24, 313–329 (1988).
[CrossRef]

Other (3)

L. Fiedler, S. Bakan, “Interferometric measurements of sea surface temperature and emissivity,” (Max-Plank-Institut für Meteorologie, Hamburg, Germany, 1997).

H. Grassl, H. Hinzpeter, “The cool skin of the ocean,” World Meterological Organisation Global Atmospheric Radiation Program (GARP) Atlantic Tropical Experiment (GATE) Rep. (British National Oceanographic Library, Southampton, UK, 1975), pp. 229–236.

C. J. Zappa, “Test of OPHIR calibration bucket using infrared imagery,” (University of Washington, Seattle, Wash., 1995).

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Figures (2)

Fig. 1
Fig. 1

(a) Sky brightness temperatures obtained from a SISTeR radiometer mounted upon the foremast of R. R. S. James Clark Ross during the AMT-7 experiment for day 287 of 1998. 80° indicates a sky view pointing at 10° above the horizon, and 0° indicates a vertically pointing sky view. (b) SSST error owing to incorrect pointing of the SISTeR radiometer sky view. (c), (d) As in (a) and (b), respectively, for day 286 of 1998. In each panel, the 40° data denote the correct sky radiance and SSST for the AMT-7 deployment geometry.

Fig. 2
Fig. 2

(a) Averaged overcast and clear-sky radiance profiles from days 286 and 287. (b) Estimated SSST errors under overcast and clear skies that are due to wind-induced sea-surface roughness at a 40° zenith viewing angle. (c) Estimated SSST errors over a wind-roughened sea surface that are due to an encroaching cloud edge at a 40° zenith viewing angle.

Equations (8)

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

Rθ, λup=θ, λBSSST, λ+1-θ, λRθ, λdown,
R¯θ¯up=¯θ¯B¯SSST+1-¯θ¯R¯θ¯down,
B¯SSST=R¯θ¯up-1-¯θ¯0R¯θ¯down¯θ¯0,
dSSSTPE=SSSTPE-SSSTtrue.
B¯¯=1/¯0R¯up¯,
R¯up¯=B¯-R¯down,
dSSSTemissive=Δθ¯ B¯¯d¯dθ¯dB¯dT=Δθ¯1/¯0B¯-R¯downd¯dθ¯dB¯dT,
dSSSTwind=SSSTwind-SSSTtrue.

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