Abstract

This paper documents a balloon-borne experiment vis-a-vis the observation of the radiance and polarization ratio of sunlight scattered by the stratospheric aerosol at near-infrared wavelengths. Described are the results and preliminary analysis of the first flight, on 15 Dec. 1983, at an altitude of 20 km. The observations, particularly the polarization features, are consistent with single scattering calculations for spherical particles with a mean radius of ~0.3 μm and with a refractive index of 1.45 at 0.85 μm; thus, the presence of sulfuric acid aerosol is corroborated.

© 1986 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. D. J. Hofmann, J. M. Rosen, “Stratospheric Sulfuric Acid Fraction and Mass Estimate for the 1982 Volcanic Eruption of El Chichon,” Geophys. Res. Lett. 10, 313 (1983).
    [CrossRef]
  2. M. P. McCormick, T. J. Swissler, W. H. Fuller, W. H. Hunt, M. T. Osborn, “Airborne and Ground-Based Lidar Measurements of the El Chichon Stratospheric Aerosol from 90°N to 56°S,” Geophys. Int. 23, 187 (1984).
  3. M. P. McCormick, P. Hamill, T. J. Pepin, T. J. Swissler, L. R. McMaster, W. P. Chu, “Satellite Studies of the Stratospheric Aerosol,” Bull. Am. Meteorol. Soc. 60, 1038 (1979).
    [CrossRef]
  4. M. Ackerman, C. Lippens, C. Muller, “Stratospheric Aerosol Properties from Earth Limb Photography,” Nature London 292, 587 (1981).
    [CrossRef]
  5. K. L. Coulson, “Effects of the El Chichon Volcanic Cloud in the Stratosphere on the Polarization of Light from the Sky,” Appl. Opt. 22, 1036 (1983).
    [CrossRef] [PubMed]
  6. J. E. Hansen, J. W. Hovenier, “Interpretation of the Polarization of Venus,” J. Atmos. Sci. 31, 1137 (1974).
    [CrossRef]
  7. F. W. Gibson, “In situ Polarimetric Observations of Angular Scattering from Atmospheric Aerosols,” Appl. Opt. 15, 2520 (1976).
    [CrossRef] [PubMed]
  8. J. C. DeVos, “A New Determination of the Emissivity of Tungsten Ribbon, Physica 20, 690 (1954).
    [CrossRef]
  9. J. Y. Balois, Mémoire de Diplôme d’Ingénieur CNAM, Mise au point, essais, étalonnage et intégration d’un radiomètre-polarimètre infra-rouge, embarquable à bord d’une plate forme stratosphérique, Mars1985, Conservatoire National des Arts et Métiers, Lille, France.
  10. R. G. Pinnick, J. M. Rosen, D. J. Hofmann, “Stratospheric Aerosol Measurements, 3, Optical Model Calculations,” J. Atmos. Sci. 33, 304 (1976).
    [CrossRef]
  11. J. L. Gras, J. E. Laby, “Southern Hemisphere Stratospheric Aerosol Measurements, 3, Size Distribution 1974–1979,” J. Geophys. Res. 86, 9767 (1981).
    [CrossRef]
  12. R. Santer et al., “Retrieval of the Stratospheric Aerosol Characteristics, from Polarization Measurements, presented at Workshop on Advances in Remote Sensing Retrieval Methods, Williamsburg, VA, 30 Oct.–2 Nov. 1984 (Deepak Publishing, Hampton, VA, 1985), to appear.
  13. J. Lenoble, P. Pruvost, C. Brogniez, “SAGE Satellite Observations of Stratospheric Aerosols from Mount St. Helens Eruption: A Two Wavelength Analysis,” J. Geophys. Res. 89, 11,666 (1984).
    [CrossRef]
  14. D. J. Hofmann, J. M. Rosen, “Time Variation of the Stratospheric Aerosol Size Distribution, After the Eruption of El Chichon,” in Proceedings, International Radiation Symposium, Pérugia, Italy, 21–28 Aug. 1984, G. Fiocco, Ed. (Deepak Publishing, Hampton, VA, 1985), pp. 111–114.
  15. D. J. Hofmann, J. M. Rosen, “Optical Modeling of Stratospheric Aerosols: Present Status,” Appl. Opt. 25, 410 (1986).
    [CrossRef] [PubMed]
  16. J. E. Hansen, L. D. Travis, “Light Scattering in Planetary Atmospheres,” Space Sci. Rev. 16, 527 (1974).
    [CrossRef]
  17. A. Adriani, F. Congeduti, G. P. Gobbi, R. Ligi, G. Fiocco, “The El Chichon Aerosol Cloud Observed by Lidar in Frascati, March 1982–April 1984, Backscattering and Extinction,” in Proceedings, International Radiation Symposium, Pérugia, Italy, 21–28 Aug. 1984, G. Fiocco, Ed. (Deepak Publishing, Hampton, VA, 1985), pp. 103–106.
  18. P. Flament, Laboratoire de Meteorologie Dynamique; G. Megie, J. Pelon, Service d’Aeronomie du CNRS; private communication.

1986 (1)

1984 (2)

M. P. McCormick, T. J. Swissler, W. H. Fuller, W. H. Hunt, M. T. Osborn, “Airborne and Ground-Based Lidar Measurements of the El Chichon Stratospheric Aerosol from 90°N to 56°S,” Geophys. Int. 23, 187 (1984).

J. Lenoble, P. Pruvost, C. Brogniez, “SAGE Satellite Observations of Stratospheric Aerosols from Mount St. Helens Eruption: A Two Wavelength Analysis,” J. Geophys. Res. 89, 11,666 (1984).
[CrossRef]

1983 (2)

D. J. Hofmann, J. M. Rosen, “Stratospheric Sulfuric Acid Fraction and Mass Estimate for the 1982 Volcanic Eruption of El Chichon,” Geophys. Res. Lett. 10, 313 (1983).
[CrossRef]

K. L. Coulson, “Effects of the El Chichon Volcanic Cloud in the Stratosphere on the Polarization of Light from the Sky,” Appl. Opt. 22, 1036 (1983).
[CrossRef] [PubMed]

1981 (2)

J. L. Gras, J. E. Laby, “Southern Hemisphere Stratospheric Aerosol Measurements, 3, Size Distribution 1974–1979,” J. Geophys. Res. 86, 9767 (1981).
[CrossRef]

M. Ackerman, C. Lippens, C. Muller, “Stratospheric Aerosol Properties from Earth Limb Photography,” Nature London 292, 587 (1981).
[CrossRef]

1979 (1)

M. P. McCormick, P. Hamill, T. J. Pepin, T. J. Swissler, L. R. McMaster, W. P. Chu, “Satellite Studies of the Stratospheric Aerosol,” Bull. Am. Meteorol. Soc. 60, 1038 (1979).
[CrossRef]

1976 (2)

R. G. Pinnick, J. M. Rosen, D. J. Hofmann, “Stratospheric Aerosol Measurements, 3, Optical Model Calculations,” J. Atmos. Sci. 33, 304 (1976).
[CrossRef]

F. W. Gibson, “In situ Polarimetric Observations of Angular Scattering from Atmospheric Aerosols,” Appl. Opt. 15, 2520 (1976).
[CrossRef] [PubMed]

1974 (2)

J. E. Hansen, J. W. Hovenier, “Interpretation of the Polarization of Venus,” J. Atmos. Sci. 31, 1137 (1974).
[CrossRef]

J. E. Hansen, L. D. Travis, “Light Scattering in Planetary Atmospheres,” Space Sci. Rev. 16, 527 (1974).
[CrossRef]

1954 (1)

J. C. DeVos, “A New Determination of the Emissivity of Tungsten Ribbon, Physica 20, 690 (1954).
[CrossRef]

Ackerman, M.

M. Ackerman, C. Lippens, C. Muller, “Stratospheric Aerosol Properties from Earth Limb Photography,” Nature London 292, 587 (1981).
[CrossRef]

Adriani, A.

A. Adriani, F. Congeduti, G. P. Gobbi, R. Ligi, G. Fiocco, “The El Chichon Aerosol Cloud Observed by Lidar in Frascati, March 1982–April 1984, Backscattering and Extinction,” in Proceedings, International Radiation Symposium, Pérugia, Italy, 21–28 Aug. 1984, G. Fiocco, Ed. (Deepak Publishing, Hampton, VA, 1985), pp. 103–106.

Balois, J. Y.

J. Y. Balois, Mémoire de Diplôme d’Ingénieur CNAM, Mise au point, essais, étalonnage et intégration d’un radiomètre-polarimètre infra-rouge, embarquable à bord d’une plate forme stratosphérique, Mars1985, Conservatoire National des Arts et Métiers, Lille, France.

Brogniez, C.

J. Lenoble, P. Pruvost, C. Brogniez, “SAGE Satellite Observations of Stratospheric Aerosols from Mount St. Helens Eruption: A Two Wavelength Analysis,” J. Geophys. Res. 89, 11,666 (1984).
[CrossRef]

Chu, W. P.

M. P. McCormick, P. Hamill, T. J. Pepin, T. J. Swissler, L. R. McMaster, W. P. Chu, “Satellite Studies of the Stratospheric Aerosol,” Bull. Am. Meteorol. Soc. 60, 1038 (1979).
[CrossRef]

Congeduti, F.

A. Adriani, F. Congeduti, G. P. Gobbi, R. Ligi, G. Fiocco, “The El Chichon Aerosol Cloud Observed by Lidar in Frascati, March 1982–April 1984, Backscattering and Extinction,” in Proceedings, International Radiation Symposium, Pérugia, Italy, 21–28 Aug. 1984, G. Fiocco, Ed. (Deepak Publishing, Hampton, VA, 1985), pp. 103–106.

Coulson, K. L.

DeVos, J. C.

J. C. DeVos, “A New Determination of the Emissivity of Tungsten Ribbon, Physica 20, 690 (1954).
[CrossRef]

Fiocco, G.

A. Adriani, F. Congeduti, G. P. Gobbi, R. Ligi, G. Fiocco, “The El Chichon Aerosol Cloud Observed by Lidar in Frascati, March 1982–April 1984, Backscattering and Extinction,” in Proceedings, International Radiation Symposium, Pérugia, Italy, 21–28 Aug. 1984, G. Fiocco, Ed. (Deepak Publishing, Hampton, VA, 1985), pp. 103–106.

Flament, P.

P. Flament, Laboratoire de Meteorologie Dynamique; G. Megie, J. Pelon, Service d’Aeronomie du CNRS; private communication.

Fuller, W. H.

M. P. McCormick, T. J. Swissler, W. H. Fuller, W. H. Hunt, M. T. Osborn, “Airborne and Ground-Based Lidar Measurements of the El Chichon Stratospheric Aerosol from 90°N to 56°S,” Geophys. Int. 23, 187 (1984).

Gibson, F. W.

Gobbi, G. P.

A. Adriani, F. Congeduti, G. P. Gobbi, R. Ligi, G. Fiocco, “The El Chichon Aerosol Cloud Observed by Lidar in Frascati, March 1982–April 1984, Backscattering and Extinction,” in Proceedings, International Radiation Symposium, Pérugia, Italy, 21–28 Aug. 1984, G. Fiocco, Ed. (Deepak Publishing, Hampton, VA, 1985), pp. 103–106.

Gras, J. L.

J. L. Gras, J. E. Laby, “Southern Hemisphere Stratospheric Aerosol Measurements, 3, Size Distribution 1974–1979,” J. Geophys. Res. 86, 9767 (1981).
[CrossRef]

Hamill, P.

M. P. McCormick, P. Hamill, T. J. Pepin, T. J. Swissler, L. R. McMaster, W. P. Chu, “Satellite Studies of the Stratospheric Aerosol,” Bull. Am. Meteorol. Soc. 60, 1038 (1979).
[CrossRef]

Hansen, J. E.

J. E. Hansen, L. D. Travis, “Light Scattering in Planetary Atmospheres,” Space Sci. Rev. 16, 527 (1974).
[CrossRef]

J. E. Hansen, J. W. Hovenier, “Interpretation of the Polarization of Venus,” J. Atmos. Sci. 31, 1137 (1974).
[CrossRef]

Hofmann, D. J.

D. J. Hofmann, J. M. Rosen, “Optical Modeling of Stratospheric Aerosols: Present Status,” Appl. Opt. 25, 410 (1986).
[CrossRef] [PubMed]

D. J. Hofmann, J. M. Rosen, “Stratospheric Sulfuric Acid Fraction and Mass Estimate for the 1982 Volcanic Eruption of El Chichon,” Geophys. Res. Lett. 10, 313 (1983).
[CrossRef]

R. G. Pinnick, J. M. Rosen, D. J. Hofmann, “Stratospheric Aerosol Measurements, 3, Optical Model Calculations,” J. Atmos. Sci. 33, 304 (1976).
[CrossRef]

D. J. Hofmann, J. M. Rosen, “Time Variation of the Stratospheric Aerosol Size Distribution, After the Eruption of El Chichon,” in Proceedings, International Radiation Symposium, Pérugia, Italy, 21–28 Aug. 1984, G. Fiocco, Ed. (Deepak Publishing, Hampton, VA, 1985), pp. 111–114.

Hovenier, J. W.

J. E. Hansen, J. W. Hovenier, “Interpretation of the Polarization of Venus,” J. Atmos. Sci. 31, 1137 (1974).
[CrossRef]

Hunt, W. H.

M. P. McCormick, T. J. Swissler, W. H. Fuller, W. H. Hunt, M. T. Osborn, “Airborne and Ground-Based Lidar Measurements of the El Chichon Stratospheric Aerosol from 90°N to 56°S,” Geophys. Int. 23, 187 (1984).

Laby, J. E.

J. L. Gras, J. E. Laby, “Southern Hemisphere Stratospheric Aerosol Measurements, 3, Size Distribution 1974–1979,” J. Geophys. Res. 86, 9767 (1981).
[CrossRef]

Lenoble, J.

J. Lenoble, P. Pruvost, C. Brogniez, “SAGE Satellite Observations of Stratospheric Aerosols from Mount St. Helens Eruption: A Two Wavelength Analysis,” J. Geophys. Res. 89, 11,666 (1984).
[CrossRef]

Ligi, R.

A. Adriani, F. Congeduti, G. P. Gobbi, R. Ligi, G. Fiocco, “The El Chichon Aerosol Cloud Observed by Lidar in Frascati, March 1982–April 1984, Backscattering and Extinction,” in Proceedings, International Radiation Symposium, Pérugia, Italy, 21–28 Aug. 1984, G. Fiocco, Ed. (Deepak Publishing, Hampton, VA, 1985), pp. 103–106.

Lippens, C.

M. Ackerman, C. Lippens, C. Muller, “Stratospheric Aerosol Properties from Earth Limb Photography,” Nature London 292, 587 (1981).
[CrossRef]

McCormick, M. P.

M. P. McCormick, T. J. Swissler, W. H. Fuller, W. H. Hunt, M. T. Osborn, “Airborne and Ground-Based Lidar Measurements of the El Chichon Stratospheric Aerosol from 90°N to 56°S,” Geophys. Int. 23, 187 (1984).

M. P. McCormick, P. Hamill, T. J. Pepin, T. J. Swissler, L. R. McMaster, W. P. Chu, “Satellite Studies of the Stratospheric Aerosol,” Bull. Am. Meteorol. Soc. 60, 1038 (1979).
[CrossRef]

McMaster, L. R.

M. P. McCormick, P. Hamill, T. J. Pepin, T. J. Swissler, L. R. McMaster, W. P. Chu, “Satellite Studies of the Stratospheric Aerosol,” Bull. Am. Meteorol. Soc. 60, 1038 (1979).
[CrossRef]

Muller, C.

M. Ackerman, C. Lippens, C. Muller, “Stratospheric Aerosol Properties from Earth Limb Photography,” Nature London 292, 587 (1981).
[CrossRef]

Osborn, M. T.

M. P. McCormick, T. J. Swissler, W. H. Fuller, W. H. Hunt, M. T. Osborn, “Airborne and Ground-Based Lidar Measurements of the El Chichon Stratospheric Aerosol from 90°N to 56°S,” Geophys. Int. 23, 187 (1984).

Pepin, T. J.

M. P. McCormick, P. Hamill, T. J. Pepin, T. J. Swissler, L. R. McMaster, W. P. Chu, “Satellite Studies of the Stratospheric Aerosol,” Bull. Am. Meteorol. Soc. 60, 1038 (1979).
[CrossRef]

Pinnick, R. G.

R. G. Pinnick, J. M. Rosen, D. J. Hofmann, “Stratospheric Aerosol Measurements, 3, Optical Model Calculations,” J. Atmos. Sci. 33, 304 (1976).
[CrossRef]

Pruvost, P.

J. Lenoble, P. Pruvost, C. Brogniez, “SAGE Satellite Observations of Stratospheric Aerosols from Mount St. Helens Eruption: A Two Wavelength Analysis,” J. Geophys. Res. 89, 11,666 (1984).
[CrossRef]

Rosen, J. M.

D. J. Hofmann, J. M. Rosen, “Optical Modeling of Stratospheric Aerosols: Present Status,” Appl. Opt. 25, 410 (1986).
[CrossRef] [PubMed]

D. J. Hofmann, J. M. Rosen, “Stratospheric Sulfuric Acid Fraction and Mass Estimate for the 1982 Volcanic Eruption of El Chichon,” Geophys. Res. Lett. 10, 313 (1983).
[CrossRef]

R. G. Pinnick, J. M. Rosen, D. J. Hofmann, “Stratospheric Aerosol Measurements, 3, Optical Model Calculations,” J. Atmos. Sci. 33, 304 (1976).
[CrossRef]

D. J. Hofmann, J. M. Rosen, “Time Variation of the Stratospheric Aerosol Size Distribution, After the Eruption of El Chichon,” in Proceedings, International Radiation Symposium, Pérugia, Italy, 21–28 Aug. 1984, G. Fiocco, Ed. (Deepak Publishing, Hampton, VA, 1985), pp. 111–114.

Santer, R.

R. Santer et al., “Retrieval of the Stratospheric Aerosol Characteristics, from Polarization Measurements, presented at Workshop on Advances in Remote Sensing Retrieval Methods, Williamsburg, VA, 30 Oct.–2 Nov. 1984 (Deepak Publishing, Hampton, VA, 1985), to appear.

Swissler, T. J.

M. P. McCormick, T. J. Swissler, W. H. Fuller, W. H. Hunt, M. T. Osborn, “Airborne and Ground-Based Lidar Measurements of the El Chichon Stratospheric Aerosol from 90°N to 56°S,” Geophys. Int. 23, 187 (1984).

M. P. McCormick, P. Hamill, T. J. Pepin, T. J. Swissler, L. R. McMaster, W. P. Chu, “Satellite Studies of the Stratospheric Aerosol,” Bull. Am. Meteorol. Soc. 60, 1038 (1979).
[CrossRef]

Travis, L. D.

J. E. Hansen, L. D. Travis, “Light Scattering in Planetary Atmospheres,” Space Sci. Rev. 16, 527 (1974).
[CrossRef]

Appl. Opt. (3)

Bull. Am. Meteorol. Soc. (1)

M. P. McCormick, P. Hamill, T. J. Pepin, T. J. Swissler, L. R. McMaster, W. P. Chu, “Satellite Studies of the Stratospheric Aerosol,” Bull. Am. Meteorol. Soc. 60, 1038 (1979).
[CrossRef]

Geophys. Int. (1)

M. P. McCormick, T. J. Swissler, W. H. Fuller, W. H. Hunt, M. T. Osborn, “Airborne and Ground-Based Lidar Measurements of the El Chichon Stratospheric Aerosol from 90°N to 56°S,” Geophys. Int. 23, 187 (1984).

Geophys. Res. Lett. (1)

D. J. Hofmann, J. M. Rosen, “Stratospheric Sulfuric Acid Fraction and Mass Estimate for the 1982 Volcanic Eruption of El Chichon,” Geophys. Res. Lett. 10, 313 (1983).
[CrossRef]

J. Atmos. Sci. (2)

R. G. Pinnick, J. M. Rosen, D. J. Hofmann, “Stratospheric Aerosol Measurements, 3, Optical Model Calculations,” J. Atmos. Sci. 33, 304 (1976).
[CrossRef]

J. E. Hansen, J. W. Hovenier, “Interpretation of the Polarization of Venus,” J. Atmos. Sci. 31, 1137 (1974).
[CrossRef]

J. Geophys. Res. (2)

J. L. Gras, J. E. Laby, “Southern Hemisphere Stratospheric Aerosol Measurements, 3, Size Distribution 1974–1979,” J. Geophys. Res. 86, 9767 (1981).
[CrossRef]

J. Lenoble, P. Pruvost, C. Brogniez, “SAGE Satellite Observations of Stratospheric Aerosols from Mount St. Helens Eruption: A Two Wavelength Analysis,” J. Geophys. Res. 89, 11,666 (1984).
[CrossRef]

Nature London (1)

M. Ackerman, C. Lippens, C. Muller, “Stratospheric Aerosol Properties from Earth Limb Photography,” Nature London 292, 587 (1981).
[CrossRef]

Physica (1)

J. C. DeVos, “A New Determination of the Emissivity of Tungsten Ribbon, Physica 20, 690 (1954).
[CrossRef]

Space Sci. Rev. (1)

J. E. Hansen, L. D. Travis, “Light Scattering in Planetary Atmospheres,” Space Sci. Rev. 16, 527 (1974).
[CrossRef]

Other (5)

A. Adriani, F. Congeduti, G. P. Gobbi, R. Ligi, G. Fiocco, “The El Chichon Aerosol Cloud Observed by Lidar in Frascati, March 1982–April 1984, Backscattering and Extinction,” in Proceedings, International Radiation Symposium, Pérugia, Italy, 21–28 Aug. 1984, G. Fiocco, Ed. (Deepak Publishing, Hampton, VA, 1985), pp. 103–106.

P. Flament, Laboratoire de Meteorologie Dynamique; G. Megie, J. Pelon, Service d’Aeronomie du CNRS; private communication.

J. Y. Balois, Mémoire de Diplôme d’Ingénieur CNAM, Mise au point, essais, étalonnage et intégration d’un radiomètre-polarimètre infra-rouge, embarquable à bord d’une plate forme stratosphérique, Mars1985, Conservatoire National des Arts et Métiers, Lille, France.

R. Santer et al., “Retrieval of the Stratospheric Aerosol Characteristics, from Polarization Measurements, presented at Workshop on Advances in Remote Sensing Retrieval Methods, Williamsburg, VA, 30 Oct.–2 Nov. 1984 (Deepak Publishing, Hampton, VA, 1985), to appear.

D. J. Hofmann, J. M. Rosen, “Time Variation of the Stratospheric Aerosol Size Distribution, After the Eruption of El Chichon,” in Proceedings, International Radiation Symposium, Pérugia, Italy, 21–28 Aug. 1984, G. Fiocco, Ed. (Deepak Publishing, Hampton, VA, 1985), pp. 111–114.

Cited By

OSA participates in CrossRef's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (17)

Fig. 1
Fig. 1

Geometry of the experiment. From balloon B, at altitude z0, the polarimeter scans across the horizontal plane P: Bx, observation direction; Δω, polarimeter field of view; hs, solar elevation; ϕs and ϕv, azimuths of the sun and of the observation directions; θ, scattering angle for primary scattering from M. Note that the altitude zM of M is ~z0 + x2/(2R).

Fig. 2
Fig. 2

Schematic of the polarimeter: L, objective lens, 6.1-cm diameter, f/7 aperture; S, field stop providing the 2° field of view; W, rotatable filter wheel; A, rotatable analyzer; C, condenser; D, germanium photodiode; TS, temperature sensors; Mw and MA, filter wheel and analyzer motors providing the respective 1- and 48-Hz rotation rates.

Fig. 3
Fig. 3

Entrance radiance is the sum Ln + Lp of natural and linearly polarized components. The perfect analyzer with period of rotation TA, therefore, will provide a signal in the form of x ( t ) ~ L n + L p 2 + L p 2 cos ( 4 π t T A ) + L 0 , where L0 accounts for the zero level. By assuming measurements with i = 1 or 2 and with i = 0 to be performed with the same gain level, x ¯ i , x ¯ 0, and s ¯ i will correspond, respectively, to (Ln + Lp)/2 + L0, L0, and 4S/TA, where S is the dashed area, i.e., S = LPTA/4.

Fig. 4
Fig. 4

Measured point spread function of the polarimeter; source size ~0.1°.

Fig. 5
Fig. 5

Main flight parameters as a function of the time: solid line, balloon altitude (left scale); dashed line, solar elevation (right scale); C, optical heat shield removed; S, usable measurements beginning.

Fig. 6
Fig. 6

A 5-min sequence of data; the sun is near the horizon. From the bottom to the top: inclinometer data (from −0.1° to +0.1°); magnetometer data (linear arbitrary scale); polarization ratio (in percent); reflectance (logarithmic scale). Small vertical arrows indicate when the observation direction is toward the sun.

Fig. 7
Fig. 7

Platform inclination as a function of time from the inclinometer data. The results correspond to the ceiling part of the flight.

Fig. 8
Fig. 8

(a) Percent polarization measurements performed at λ = 1.65 μm, during a whole platform revolution. The mean solar elevation is +0.1°. Measurements have been reported as a function of the scattering angle. Different labels distinguish the two sides of the sun incident plane where the measurements are performed. The full curve is the expected percent polarization for pure molecular scattering. (b) Same as (a) but for reflectance measurements at λ = 1.65 μm. (c) Same as (a) but for percent polarization measurements at 0.85 μm. (d) Same as (a) but for reflectance measurements at λ = 0.85 μm.

Fig. 9
Fig. 9

Polarization diagrams for scattering by monodispersed spherical particles with Mie parameter α = 2πr/λ ranging from 0 to 2. The particle refractive index is m = 1.45, but similar polarization behaviors are obtained with m ranging from 1.33 to 1.55.

Fig. 10
Fig. 10

Different scans of the reflectance performed with different solar elevations, at λ = 1.65 μm, are plotted as a function of the scattering angle. The insets illustrate in which manner transmission effects explain the mean reflectance behavior. Tropospheric influence also exists for positive hs.

Fig. 11
Fig. 11

Same legend as in Fig. 10 but for the polarization at λ = 1.65 μm. Transmission variations have negligible influence. The main observed effect is the signal depolarization from the tropospheric diffuse light for positive hs.

Fig. 12
Fig. 12

Atmospheric transmission along the mean path from the sun to the balloon—when the sun is just at the balloon horizon—as a function of the observation direction. Given the aerosol slant optical thickness, ta(θ) was calculated with different choices of the aerosol scale height.

Fig. 13
Fig. 13

For hydrated sulfuric acid particles the parameters ( r ¯,σ) of the lognormal size distributions able to match the polarization measurements at λ = 1.65 μm are given as a curve lnσ vs r ¯.

Fig. 14
Fig. 14

Values of the phase function for scattering angle θ = 30° calculated for the aerosol models in Fig. 13. Results are given at the two observation wavelengths as a function of the model mean radius r ¯.

Fig. 15
Fig. 15

Ratio of the scattering coefficients at the two observation wavelengths for the aerosol models in Fig. 13.

Fig. 16
Fig. 16

Position of the neutral point θN at λ = 0.85 μm as predicted by the aerosol models in Fig. 13. The molecular contribution is accounted for [see Eq. (19)]. Given the uncertainty in τa, θN was estimated with T = 0.4 (dashed line) and τa = 0.9 (solid line) in Eq. (19). Observed position: θN = 140° ± 2.

Fig. 17
Fig. 17

(a) Percent polarization at λ = 1.65 μm. Measurement dots are compared with results predicted by the two extreme retrieved aerosol models: solid line, model of Eq. (25); dashed line, model of Eq. (26). The results for these two models are indiscernible. (b) Same as (a) but for the reflectance at λ = 1.65 μm. (c) Same as (a) but for the percent polarization at λ = 0.85 μm. (d) Same as (a) but for the reflectance at λ = 0.85 μm.

Equations (29)

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

cos θ = - cos h s cos ( ϕ s - ϕ v ) .
x ¯ i = 1 N j = 1 N x j i ;             s ¯ i = 1 n j = 1 N x j i - x ¯ i
P m = π s ¯ i 2 ( x ¯ i - x ¯ 0 ) ,
L = K ( x ¯ i - x ¯ 0 ) ,
ρ = π L E .
10 - 4 ρ 10 ;             Δ ρ / ρ 0.05 and NED ρ = 5 × 10 - 5 at 0.85 μ m ,
10 - 4 ρ 7 ;             Δ ρ / ρ 0.30 a n d NED ρ = 3.5 × 10 - 5 at 1.65 μ m .
j = 1 N x j - x ¯
σ i ( x ) σ i [ z 0 + x 2 / ( 2 R ) ] ,             i = a , m ,
σ m ( z ) = σ m ( z 0 ) exp [ - ( z - z 0 ) / H m ] ,
σ a ( z ) = σ a ( z 0 ) exp [ - ( z - z 0 ) / H a ] .
τ i = 0 σ i ( x ) d x ;             i = a , m ,
τ i = σ i ( z 0 ) π R H i / 2 ,             i = a , m .
ρ a ( θ ) = 1 4 0 exp [ - τ ( x ) ] σ a ( x ) p a ( x , θ ) d x ,
ρ a ( θ ) = t a ( θ ) 4 τ a p a ( θ )
t a ( θ ) = 0 exp [ - τ ( x ) ] σ a ( x ) d x / 0 σ a ( x ) d x ,
ρ ( θ ) = t ( θ ) 4 [ τ a p a ( θ ) + τ m p m ( θ ) ] ,
ρ ρ ( θ ) = t ( θ ) 4 [ τ a P a ( θ ) p a ( θ ) + τ m P m ( θ ) p m ( θ ) ] ,
P ( θ ) = τ a P a ( θ ) p a ( θ ) + τ m P m ( θ ) p m ( θ ) τ a p a ( θ ) + τ m p m ( θ ) ,
P ( θ ) P a ( θ ) { 1 + [ P m ( θ ) - P a ( θ ) ] τ m p m ( θ ) τ m p m ( θ ) + τ a p a ( θ ) } ,
P ( θ ) = P a ( θ )             at λ = 1.65 μ m ,
n ( r ) = Λ 2 π ln σ r exp [ - ln 2 ( r / r ¯ ) 2 ln 2 σ ] ,
τ a exp ( - τ a ) = 4 ρ ( 30 ° ) / p a ( 30 ° ) .
0.4 τ a ( 0.85 μ m ) 0.9.
τ m ( 1.65 μ m ) = 0.003 ;             τ m ( 0.85 μ m ) = 0.04.
r ¯ = 0.33 μ m ; σ = 1.27 ;             τ a ( 0.85 μ m ) = 0.40 ; τ a ( 1.65 μ m ) = 0.095 ,
r ¯ = 0.19 μ m ; σ = 1.50 ;             τ a ( 0.85 μ m ) = 0.90 ; τ a ( 1.65 μ m ) = 0.215 ,
R = 1 + σ a p a ( 180 ° ) σ m p m ( 180 ° )
x ( t ) ~ L n + L p 2 + L p 2 cos ( 4 π t T A ) + L 0 ,

Metrics