Abstract

A novel automated ground-based star-pointing spectrometer system has been constructed for long-term deployment in Antarctica. Similar to our earlier stellar system, a two-dimensional detector array measures the spectra of the star and the adjacent sky, so that auroral emission from the sky can be subtracted from the stellar signal. Some new features are an altitude–azimuth pointing mirror, so that the spectrometer does not move; slip rings to provide its power thereby avoiding flexing of cables and restriction of all-around viewing; and a glazed enclosure around the mirror to ensure protection from rain and snow, made from flat plates to avoid changing the focal length of the telescope. The optical system can also view sunlight scattered from the zenith sky. The system automatically points and tracks selected stars and switches to other views on command. The system is now installed at Halley in Antarctica, and some preliminary measurements of ozone from Antarctica are shown.

© 1997 Optical Society of America

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  1. H. K. Roscoe, R. A. Freshwater, R. Wolfenden, R. L. Jones, D. J. Fish, J. E. Harries, D. J. Oldham, “Using stars for remote sensing of the Earth’s stratosphere,” Appl. Opt. 33, 7126–7131 (1994).
    [CrossRef] [PubMed]
  2. J-P. Pommereau, F. Goutail, “Stratospheric O3 and NO2 observations at the southern polar circle in summer and fall 1988,” Geophys. Res. Lett. 15, 895–897 (1988).
    [CrossRef]
  3. H. K. Roscoe, J. A. C. Squires, D. J. Oldham, A. Sarkissian, J-P. Pommereau, F. Goutail, “Improvements to the accuracy of zenith-sky measurements of total ozone by visible spectrometers,” J. Quant. Spectrosc. Radiat. Transfer 52, 639–648 (1994).
    [CrossRef]
  4. H. K. Roscoe, “A star-pointing UV–visible spectrometer for polar stratospheric measurements,” in Proceedings of the First European Workshop on Polar Stratospheric Ozone Research, J. A. Pyle, N. R. P. Harris, eds. (Commission of the European Communities, Brussels, 1991), pp. 91–94.
  5. D. J. Fish, R. L. Jones, R. A. Freshwater, H. K. Roscoe, D. J. Oldham, J. E. Harries, “Total ozone measured during EASOE by a UV–visible spectrometer which observes stars,” Geophys. Res. Lett. 21, 1387–1390 (1994).
    [CrossRef]
  6. D. J. Fish, “Measurements of stratospheric composition using ultraviolet and visible spectroscopy,” Ph.D. dissertation (University of Cambridge, Cambridge, UK, 1994).
  7. M. Q. Syed, A. W. Harrison, “Ground based observations of stratospheric nitrogen dioxide,” Can. J. Phys. 58, 788–802 (1980).
    [CrossRef]

1994 (3)

H. K. Roscoe, J. A. C. Squires, D. J. Oldham, A. Sarkissian, J-P. Pommereau, F. Goutail, “Improvements to the accuracy of zenith-sky measurements of total ozone by visible spectrometers,” J. Quant. Spectrosc. Radiat. Transfer 52, 639–648 (1994).
[CrossRef]

D. J. Fish, R. L. Jones, R. A. Freshwater, H. K. Roscoe, D. J. Oldham, J. E. Harries, “Total ozone measured during EASOE by a UV–visible spectrometer which observes stars,” Geophys. Res. Lett. 21, 1387–1390 (1994).
[CrossRef]

H. K. Roscoe, R. A. Freshwater, R. Wolfenden, R. L. Jones, D. J. Fish, J. E. Harries, D. J. Oldham, “Using stars for remote sensing of the Earth’s stratosphere,” Appl. Opt. 33, 7126–7131 (1994).
[CrossRef] [PubMed]

1988 (1)

J-P. Pommereau, F. Goutail, “Stratospheric O3 and NO2 observations at the southern polar circle in summer and fall 1988,” Geophys. Res. Lett. 15, 895–897 (1988).
[CrossRef]

1980 (1)

M. Q. Syed, A. W. Harrison, “Ground based observations of stratospheric nitrogen dioxide,” Can. J. Phys. 58, 788–802 (1980).
[CrossRef]

Fish, D. J.

H. K. Roscoe, R. A. Freshwater, R. Wolfenden, R. L. Jones, D. J. Fish, J. E. Harries, D. J. Oldham, “Using stars for remote sensing of the Earth’s stratosphere,” Appl. Opt. 33, 7126–7131 (1994).
[CrossRef] [PubMed]

D. J. Fish, R. L. Jones, R. A. Freshwater, H. K. Roscoe, D. J. Oldham, J. E. Harries, “Total ozone measured during EASOE by a UV–visible spectrometer which observes stars,” Geophys. Res. Lett. 21, 1387–1390 (1994).
[CrossRef]

D. J. Fish, “Measurements of stratospheric composition using ultraviolet and visible spectroscopy,” Ph.D. dissertation (University of Cambridge, Cambridge, UK, 1994).

Freshwater, R. A.

D. J. Fish, R. L. Jones, R. A. Freshwater, H. K. Roscoe, D. J. Oldham, J. E. Harries, “Total ozone measured during EASOE by a UV–visible spectrometer which observes stars,” Geophys. Res. Lett. 21, 1387–1390 (1994).
[CrossRef]

H. K. Roscoe, R. A. Freshwater, R. Wolfenden, R. L. Jones, D. J. Fish, J. E. Harries, D. J. Oldham, “Using stars for remote sensing of the Earth’s stratosphere,” Appl. Opt. 33, 7126–7131 (1994).
[CrossRef] [PubMed]

Goutail, F.

H. K. Roscoe, J. A. C. Squires, D. J. Oldham, A. Sarkissian, J-P. Pommereau, F. Goutail, “Improvements to the accuracy of zenith-sky measurements of total ozone by visible spectrometers,” J. Quant. Spectrosc. Radiat. Transfer 52, 639–648 (1994).
[CrossRef]

J-P. Pommereau, F. Goutail, “Stratospheric O3 and NO2 observations at the southern polar circle in summer and fall 1988,” Geophys. Res. Lett. 15, 895–897 (1988).
[CrossRef]

Harries, J. E.

H. K. Roscoe, R. A. Freshwater, R. Wolfenden, R. L. Jones, D. J. Fish, J. E. Harries, D. J. Oldham, “Using stars for remote sensing of the Earth’s stratosphere,” Appl. Opt. 33, 7126–7131 (1994).
[CrossRef] [PubMed]

D. J. Fish, R. L. Jones, R. A. Freshwater, H. K. Roscoe, D. J. Oldham, J. E. Harries, “Total ozone measured during EASOE by a UV–visible spectrometer which observes stars,” Geophys. Res. Lett. 21, 1387–1390 (1994).
[CrossRef]

Harrison, A. W.

M. Q. Syed, A. W. Harrison, “Ground based observations of stratospheric nitrogen dioxide,” Can. J. Phys. 58, 788–802 (1980).
[CrossRef]

Jones, R. L.

D. J. Fish, R. L. Jones, R. A. Freshwater, H. K. Roscoe, D. J. Oldham, J. E. Harries, “Total ozone measured during EASOE by a UV–visible spectrometer which observes stars,” Geophys. Res. Lett. 21, 1387–1390 (1994).
[CrossRef]

H. K. Roscoe, R. A. Freshwater, R. Wolfenden, R. L. Jones, D. J. Fish, J. E. Harries, D. J. Oldham, “Using stars for remote sensing of the Earth’s stratosphere,” Appl. Opt. 33, 7126–7131 (1994).
[CrossRef] [PubMed]

Oldham, D. J.

H. K. Roscoe, R. A. Freshwater, R. Wolfenden, R. L. Jones, D. J. Fish, J. E. Harries, D. J. Oldham, “Using stars for remote sensing of the Earth’s stratosphere,” Appl. Opt. 33, 7126–7131 (1994).
[CrossRef] [PubMed]

D. J. Fish, R. L. Jones, R. A. Freshwater, H. K. Roscoe, D. J. Oldham, J. E. Harries, “Total ozone measured during EASOE by a UV–visible spectrometer which observes stars,” Geophys. Res. Lett. 21, 1387–1390 (1994).
[CrossRef]

H. K. Roscoe, J. A. C. Squires, D. J. Oldham, A. Sarkissian, J-P. Pommereau, F. Goutail, “Improvements to the accuracy of zenith-sky measurements of total ozone by visible spectrometers,” J. Quant. Spectrosc. Radiat. Transfer 52, 639–648 (1994).
[CrossRef]

Pommereau, J-P.

H. K. Roscoe, J. A. C. Squires, D. J. Oldham, A. Sarkissian, J-P. Pommereau, F. Goutail, “Improvements to the accuracy of zenith-sky measurements of total ozone by visible spectrometers,” J. Quant. Spectrosc. Radiat. Transfer 52, 639–648 (1994).
[CrossRef]

J-P. Pommereau, F. Goutail, “Stratospheric O3 and NO2 observations at the southern polar circle in summer and fall 1988,” Geophys. Res. Lett. 15, 895–897 (1988).
[CrossRef]

Roscoe, H. K.

H. K. Roscoe, J. A. C. Squires, D. J. Oldham, A. Sarkissian, J-P. Pommereau, F. Goutail, “Improvements to the accuracy of zenith-sky measurements of total ozone by visible spectrometers,” J. Quant. Spectrosc. Radiat. Transfer 52, 639–648 (1994).
[CrossRef]

D. J. Fish, R. L. Jones, R. A. Freshwater, H. K. Roscoe, D. J. Oldham, J. E. Harries, “Total ozone measured during EASOE by a UV–visible spectrometer which observes stars,” Geophys. Res. Lett. 21, 1387–1390 (1994).
[CrossRef]

H. K. Roscoe, R. A. Freshwater, R. Wolfenden, R. L. Jones, D. J. Fish, J. E. Harries, D. J. Oldham, “Using stars for remote sensing of the Earth’s stratosphere,” Appl. Opt. 33, 7126–7131 (1994).
[CrossRef] [PubMed]

H. K. Roscoe, “A star-pointing UV–visible spectrometer for polar stratospheric measurements,” in Proceedings of the First European Workshop on Polar Stratospheric Ozone Research, J. A. Pyle, N. R. P. Harris, eds. (Commission of the European Communities, Brussels, 1991), pp. 91–94.

Sarkissian, A.

H. K. Roscoe, J. A. C. Squires, D. J. Oldham, A. Sarkissian, J-P. Pommereau, F. Goutail, “Improvements to the accuracy of zenith-sky measurements of total ozone by visible spectrometers,” J. Quant. Spectrosc. Radiat. Transfer 52, 639–648 (1994).
[CrossRef]

Squires, J. A. C.

H. K. Roscoe, J. A. C. Squires, D. J. Oldham, A. Sarkissian, J-P. Pommereau, F. Goutail, “Improvements to the accuracy of zenith-sky measurements of total ozone by visible spectrometers,” J. Quant. Spectrosc. Radiat. Transfer 52, 639–648 (1994).
[CrossRef]

Syed, M. Q.

M. Q. Syed, A. W. Harrison, “Ground based observations of stratospheric nitrogen dioxide,” Can. J. Phys. 58, 788–802 (1980).
[CrossRef]

Wolfenden, R.

Appl. Opt. (1)

Can. J. Phys. (1)

M. Q. Syed, A. W. Harrison, “Ground based observations of stratospheric nitrogen dioxide,” Can. J. Phys. 58, 788–802 (1980).
[CrossRef]

Geophys. Res. Lett. (2)

J-P. Pommereau, F. Goutail, “Stratospheric O3 and NO2 observations at the southern polar circle in summer and fall 1988,” Geophys. Res. Lett. 15, 895–897 (1988).
[CrossRef]

D. J. Fish, R. L. Jones, R. A. Freshwater, H. K. Roscoe, D. J. Oldham, J. E. Harries, “Total ozone measured during EASOE by a UV–visible spectrometer which observes stars,” Geophys. Res. Lett. 21, 1387–1390 (1994).
[CrossRef]

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

H. K. Roscoe, J. A. C. Squires, D. J. Oldham, A. Sarkissian, J-P. Pommereau, F. Goutail, “Improvements to the accuracy of zenith-sky measurements of total ozone by visible spectrometers,” J. Quant. Spectrosc. Radiat. Transfer 52, 639–648 (1994).
[CrossRef]

Other (2)

H. K. Roscoe, “A star-pointing UV–visible spectrometer for polar stratospheric measurements,” in Proceedings of the First European Workshop on Polar Stratospheric Ozone Research, J. A. Pyle, N. R. P. Harris, eds. (Commission of the European Communities, Brussels, 1991), pp. 91–94.

D. J. Fish, “Measurements of stratospheric composition using ultraviolet and visible spectroscopy,” Ph.D. dissertation (University of Cambridge, Cambridge, UK, 1994).

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Figures (10)

Fig. 1
Fig. 1

(a) Schematic and (b) mechanical drawing of the new UV–visible spectrometer for stellar measurements from Halley in Antarctica (UVIZ). This optical scheme allows the spectrometer to be stationary, rather than to swivel with the telescope. The pointing mirror directs light from stars within 40° of the horizon into the telescope, which rotates with the mirror so that slip rings and an azimuth encoder of modest diameter can be used.

Fig. 2
Fig. 2

UVIZ in its environmental housing at Halley. The housing is waterproof and snow proof and contains heating and cooling systems. The top part of the timber frame was triangulated for extra rigidity, and the verticals can be split to insert extra lengths after each year’s snow accumulation. A third of the frame is buried to rest on the more stable snow below the surface.

Fig. 3
Fig. 3

Temperatures in the UVIZ during its first autumn of operation at Halley. Gaps in data occurred during extended fault-finding operations. The temperature of the spectrometer became uncontrolled at external temperatures below -40 °C, and above -10 °C in strong sunlight in summer, resulting in a larger drift in wavelength calibration. Although wavelengths are determined for each spectrum, errors in wavelength are larger when drift is larger.

Fig. 4
Fig. 4

Spectra of Sirius observed with the UVIZ at Cambridge on 7 February 1994. The different spectra are at different elevation angles, 21, 20, 16, 13, and 9°, with the smallest signal being at the lowest elevation. Integration time of each spectrum was 30 min.

Fig. 5
Fig. 5

Analysis of the ratio of the two spectra in Fig. 4 (Sirius at Cambridge on 7 February 1994). The lower traces are the measured (noisier) and fitted (smoother) differential optical depths (see text). The upper trace is the cross section of ozone, smoothed by the spectral resolution of the spectrometer and multiplied by the amount of ozone from the fit, displaced for clarity. Other absorbers are NO2, H2O, and O4.

Fig. 6
Fig. 6

Slant columns of ozone analyzed from all spectra for the night of 7 February 1994 (Sirius at Cambridge) plotted against the ratio of the slant path length to the vertical path length (AMF) calculated for the elevation of Sirius and for an absorber at 25 km. Error bars are those due to the residuals in the spectral fit, assuming they are random. The line is the weighted least-squares fit to the points and has a zero slant column when the AMF is 2.60. In such a Langley plot, the column should be zero at the AMF of the reference spectrum, here equal to 2.72. One Dobson Unit (DU) is 2.6818 × 1016 molecules cm-2.

Fig. 7
Fig. 7

Same as Fig. 4 but at Halley in Antarctica on the night of 2 August 1995 and at elevation angles between 2.4° and 14°. The spectra are noisier than those of Fig. 4 because air leaked into the evacuated detector encapsulation during shipping, so that the detector could not be cooled completely. Its warmer temperature (approximately -10 °C) means that the detector has more dark current.

Fig. 8
Fig. 8

Same as Fig. 5 except for Sirius at Halley on 2 August 1995. Despite the noisy spectra, the error in slant amount of ozone that is due to residuals in the fit is <35% and much of this is an artifact of a too large emission spike at 519 nm caused by a spectral lamp on a building.

Fig. 9
Fig. 9

Same as Fig. 6 except for Sirius at Halley on 2 August 1995. The line is the weighted least-squares fit to points with an AMF greater than 2.5; see text for discussion. Points at AMF’s of 10.1 and 11 are not shown because they add little information: their error bars exceed ±2000 DU because of weaker signals within 3° of the horizon. Nevertheless, the range of the AMF is double that of Fig. 6.

Fig. 10
Fig. 10

Same as Fig. 5 except for the zenith sky at Halley during the morning twilight on 6 September 1995 at a solar zenith angle of 91.2°. Note the high quality of the data; the dark current is still small compared to the signals from the sunlit zenith sky.

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