Physics
Scientific paper
Dec 2010
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010agufmsa41a1713s&link_type=abstract
American Geophysical Union, Fall Meeting 2010, abstract #SA41A-1713
Physics
[2407] Ionosphere / Auroral Ionosphere, [2431] Ionosphere / Ionosphere/Magnetosphere Interactions, [2494] Ionosphere / Instruments And Techniques
Scientific paper
Discrete stable auroral arcs are investigated during a coordinated campaign held in March 2008 between the European Incoherent Scatter Radar (EISCAT) located in Tromsø, Norway, and the Auroral Large Imaging System (ALIS) in Sweden. The ALIS network consists of five ground-based stations equipped with optical cameras that observe simultaneously the same volume of sky at altitudes above 90 km. From optical observations with ALIS, the 3D volume emission rates of the N2+(427.8nm), OI(557.7nm) and OI(630.0nm) lines are reconstructed with tomography-like inversion techniques. The 2D energy spectra of precipitating electrons can then be retrieved using the N2+ line since the N2+ 1N(0,1) first negative band volume emission rate is directly proportional to the ionisation rate (Itikawa [1986, 2006], Rees [1989]) and eventually to the precipitating electron flux (Janhunen, 2001). From IS radar observations of electron density along magnetic zenith, we can also infer the energy spectrum of precipitating electrons by using a method similar to that of Semeter and Kalamabadi (2005). Both results are matching in energy and shape with a typical average precipitation energy of a few keV. The spatial and temporal extent of the auroral arcs is also assessed using as parameters the average arc width in different wavelengths and the distribution of the electron characteristic energy along the arc. Finally we present the TRANS4 1D kinetic/fluid electron transport model and use the average energy spectrum of electrons deduced from ALIS data as input. Computed auroral emissions are compared to ALIS observations while electron density profiles are compared to EISCAT profiles. Predictions on the ion composition, ion chemistry and backscattered fluxes are highlighted.
Brändström Urban
de Keyser J. M.
Gustavsson Björn
Lamy Herve
Sandahl Ingrid
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