Ionospheric conductances due to auroral proton and electron precipitation 
deduced from IMAGE-FUV observations

V. Coumans (1), B. Hubert (1), M. Meurant (1), J.-C. Gerard (1), 
V. I. Shematovich (2) and D. V. Bisikalo (2)

(1) LPAP, Universite de Liege, Belgium
(2) Institute of Astronomy, Russian Academy of Sciences. 
    (v.coumans@ulg.ac.be/Fax: +32-4-2547573)
	
	
The FUV instrument on the IMAGE (Imager for Magnetopause-to-Aurora Global 
Exploration) satellite monitors the aurora in three different spectral regions. 
The Wide-band Imaging Camera (WIC) observes the molecular N2 LBH and the atomic 
NI emissions at 140-180 nm. The two channels of the Spectrographic Imager (SI) 
observe the Doppler shifted Lyman-alpha emission at 121.8 nm due to 
precipitating protons (SI12) and the electron auroral emission of OI at 
135.6 nm (SI13). We calculate the Pedersen and Hall ionospheric conductances 
due to auroral particles based on FUV observations separately for the proton 
and electron precipitation. We first estimate the electron and proton energy 
fluxes from the FUV data, relying on energy degradation and auroral emission 
models. A two-stream model is used for the electron aurora while the proton 
aurora modeling is based on the direct Monte Carlo method, which gives a 
stochastic solution to the Boltzmann equations for the H + - H beam. The 
electron energy is evaluated by combining observations from the three FUV 
instruments. For the proton energy, we use a statistical model based on in-situ 
particle measurements. Second, the particle energy and energy flux are used to 
estimate the ionization rates separately for protons and electrons, 
consistently with the energy degradation models. Finally, the electron and ion 
densities are estimated from ionization profiles, and the Pedersen and Hall 
conductances are calculated from fundamental equations. Applications of the 
method to the distribution of the conductance at winter solstice in the course 
of substorm development over the north polar region will be illustrated.

_______________
To be presented at the EGS Meeting, Nice, France, April 22, 2002