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Simultaneous imaging of aurora on small scale in OI (777.4 nm) and N21P to estimate energy and flux of precipitation

Simultaneous imaging of aurora on small scale in OI (777.4 nm) and N21P to estimate energy and flux of precipitation
Simultaneous imaging of aurora on small scale in OI (777.4 nm) and N21P to estimate energy and flux of precipitation
Simultaneous images of the aurora in three emissions, N21P (673.0 nm), OII (732.0 nm) and OI (777.4 nm), have been analysed; the ratio of atomic oxygen to molecular nitrogen has been used to provide estimates of the changes in energy and flux of precipitation within scale sizes of 100 m, and with temporal resolution of 32 frames per second. The choice of filters for the imagers is discussed, with particular emphasis on the choice of the atomic oxygen line at 777.4 nm as one of the three emissions measured. The optical measurements have been combined with radar measurements and compared with the results of an auroral model, hence showing that the ratio of emission rates OI/N2 can be used to estimate the energy within the smallest auroral structures. In the event chosen, measurements were made from mainland Norway, near Troms\o, (69.6 N, 19.2 E). The peak energies of precipitation were between 1–15 keV. In a narrow curling arc, it was found that the arc filaments resulted from energies in excess of 10 keV and fluxes of approximately 7 mW/m2. These filaments of the order of 100 m in width were embedded in a region of lower energies (about 5–10 keV) and fluxes of about 3 mW/m2. The modelling results show that the method promises to be most powerful for detecting low energy precipitation, more prevalent at the higher latitudes of Svalbard where the multispectral imager, known as ASK, is now installed.
0992-7689
2881-2891
Lanchester, B.S.
e864533e-eea0-471f-a3f9-7c70c25be55b
Ashrafi, M.
fb831af1-1df3-4d60-9071-2ae3637b4944
Ivchenko, N.
c892df9e-e2a0-450f-bf77-2673e029f565
Lanchester, B.S.
e864533e-eea0-471f-a3f9-7c70c25be55b
Ashrafi, M.
fb831af1-1df3-4d60-9071-2ae3637b4944
Ivchenko, N.
c892df9e-e2a0-450f-bf77-2673e029f565

Lanchester, B.S., Ashrafi, M. and Ivchenko, N. (2009) Simultaneous imaging of aurora on small scale in OI (777.4 nm) and N21P to estimate energy and flux of precipitation. Annales Geophysicae, 27 (7), 2881-2891. (doi:10.5194/angeo-27-2881-2009).

Record type: Article

Abstract

Simultaneous images of the aurora in three emissions, N21P (673.0 nm), OII (732.0 nm) and OI (777.4 nm), have been analysed; the ratio of atomic oxygen to molecular nitrogen has been used to provide estimates of the changes in energy and flux of precipitation within scale sizes of 100 m, and with temporal resolution of 32 frames per second. The choice of filters for the imagers is discussed, with particular emphasis on the choice of the atomic oxygen line at 777.4 nm as one of the three emissions measured. The optical measurements have been combined with radar measurements and compared with the results of an auroral model, hence showing that the ratio of emission rates OI/N2 can be used to estimate the energy within the smallest auroral structures. In the event chosen, measurements were made from mainland Norway, near Troms\o, (69.6 N, 19.2 E). The peak energies of precipitation were between 1–15 keV. In a narrow curling arc, it was found that the arc filaments resulted from energies in excess of 10 keV and fluxes of approximately 7 mW/m2. These filaments of the order of 100 m in width were embedded in a region of lower energies (about 5–10 keV) and fluxes of about 3 mW/m2. The modelling results show that the method promises to be most powerful for detecting low energy precipitation, more prevalent at the higher latitudes of Svalbard where the multispectral imager, known as ASK, is now installed.

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Published date: 2009

Identifiers

Local EPrints ID: 147135
URI: http://eprints.soton.ac.uk/id/eprint/147135
ISSN: 0992-7689
PURE UUID: af423114-af6b-4db9-9a54-617984740414

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Date deposited: 23 Apr 2010 09:57
Last modified: 14 Mar 2024 00:57

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Contributors

Author: B.S. Lanchester
Author: M. Ashrafi
Author: N. Ivchenko

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