 |
| Titel |
Rotational temperature of N2+ (0,2) ions from spectrographic measurements used to infer the energy of precipitation in different auroral forms and compared with radar measurements |
| VerfasserIn |
O. Jokiaho, B. S. Lanchester, N. Ivchenko, G. J. Daniell, L. C. H. Miller, D. Lummerzheim |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
0992-7689
|
| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 26, no. 4 ; Nr. 26, no. 4 (2008-05-13), S.853-866 |
| Datensatznummer |
250016066
|
| Publikation (Nr.) |
 copernicus.org/angeo-26-853-2008.pdf |
|
|
|
|
|
| Zusammenfassung |
| High resolution spectral data are used to estimate neutral
temperatures at auroral heights. The data are from the High
Throughput Imaging Echelle Spectrograph (HiTIES) which forms part
of the Spectrographic Imaging Facility (SIF), located at
Longyearbyen, Svalbard in Norway. The platform also contains
photometers and a narrow angle auroral imager. Quantum molecular
spectroscopy is used for modelling N2+ 1NG (0,2), which
serves as a diagnostic tool for neutral temperature and emission
height variations. The theoretical spectra are convolved with the
instrument function and fitted to measured rotational transition
lines as a function of temperature. Measurements were made in the
magnetic zenith, and along a meridian slit centred on the magnetic
zenith. In the results described, the high spectral resolution of
the data (0.08 nm) allows an error analysis to be performed more
thoroughly than previous findings, with particular attention paid
to the correct subtraction of background, and to precise
wavelength calibration. Supporting measurements were made with the
Svalbard Eiscat Radar (ESR). Estimates were made from both optical
and radar observations of the average energy of precipitating
electrons in different types of aurora. These provide confirmation
that the spectral results are in agreement with the variations
observed in radar profiles. In rayed aurora the neutral
temperature was highest (800 K) and the energy lowest (1 keV). In
a bright curling arc, the temperature at the lower border was
about 550 K, corresponding to energies of 2 keV. The radar and
modelling results confirm that these average values are a lower
limit for an estimation of the characteristic energy. In each
event the energy distribution is clearly made up of more than one
spectral shape. This work emphasises the need for high time
resolution as well as high spectral resolution. The present work
is the first to provide rotational temperatures using a
method which pays particular attention to errors in measurement
and fitting, and background subtraction. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|