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| Titel |
Hydroxyl temperature and intensity measurements during noctilucent cloud displays |
| VerfasserIn |
M. J. Taylor, R. P. Lowe, D. J. Baker |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 13, no. 10 ; Nr. 13, no. 10, S.1107-1116 |
| Datensatznummer |
250012013
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| Publikation (Nr.) |
 copernicus.org/angeo-13-1107-1995.pdf |
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| Zusammenfassung |
| Two Fourier transform spectrometers have been
used to investigate the properties of the near-infrared hydroxyl (OH) nightglow
emission under high-latitude summertime conditions and any association with
noctilucent clouds (NLCs). The measurements were made from Poker Flat Research
Range, Alaska (65.1°N, 147.5°W), during August 1986. Simultaneous photographic
observations of the northern twilight sky were made from Gulkana, Alaska (62.2°N,
145.5°W), approximately 340 km to the south to establish the presence of NLCs
over the spectrometer site. Data exhibiting significant short-term variations in
the relative intensity (as much as 50–100%) and rotational temperature
(typically 5–15 K) were recorded on six occasions when NLCs were observed. Joint
measurements were also obtained on several "cloud-free" nights. No
obvious relationship was found linking the mean OH intensity or its variation
with the occurrence of NLCs. However, a clear tendency was found for the mean OH
temperature to be lower on NLC nights than on cloud-free nights. In particular,
a significant fraction of the OH(3–1) band spectra recorded by each instrument
(16–57%) exhibited temperatures below ~154 K on NLC nights compared with <3%
on cloud-free nights. This result is qualitatively consistent with current
models for ice particle nucleation and growth, but the mean OH temperature on
NLC nights (~156 K) was significantly higher than would be expected for
long-term particle growth in this region. These observations raise questions
concerning the expected proximity of the high-latitude, summertime OH layer and
the NLC growth region. |
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