Interference filter spectral imaging of twilight O<sup>+</sup>(<sup>2</sup>P-<sup>2</sup>D) emission
A spectral imager specifically designed to measure the O<sup>+</sup>(<sup>2</sup>P-<sup>2</sup>D) emission in the thermosphere during twilight has been constructed and tested in Toronto (43.8°N, 79.3°W), and found to show promise for long-term and campaign-mode...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
1995-02-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/13/189/1995/angeo-13-189-1995.pdf |
| Summary: | A spectral imager specifically designed to
measure the O<sup>+</sup>(<sup>2</sup>P-<sup>2</sup>D) emission in the
thermosphere during twilight has been constructed and tested in Toronto (43.8°N,
79.3°W), and found to show promise for long-term and campaign-mode operations.
A modification of the mesopause oxygen rotational temperature imager (MORTI), it
consists basically of a narrow-band interference filter (0.14 nm bandwidth) to
separate wavelengths as a function of off-axis angle, a lens to focus the
spectrum into a series of concentric rings, and a focal plane array (CCD) to
record the spectral images in digital form. The instrument was built with two
fields of view, one for the zenith and one for 20° above the horizon, movable
to track the azimuth of the Sun, in order to provide appropriate data for
inversion. Data gathered during June 1991 provided measurements of the
column-integrated emission rate with a precision of about 3%. An atomic oxygen
profile was deduced that showed good agreement with that predicted by the
MSIS-90 model atmosphere. Geomagnetically induced variations of the O<sup>+</sup>
lines, calcium spectra resulting from meteor showers, and OH nightglow were also
observed. |
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| ISSN: | 0992-7689 1432-0576 |