Quasi exhaustive synthetic spectra of the aurora and spectrometers measurements

Abstract

Studying the auroral emission is of strong importance since they are created in an atmospheric layer (80-300 km) where in situ measurements are complicated. They represent a good proxy of the particle precipitations into atmosphere.The spectrum of the aurora is complex made of both atomic and molecular lines. The intensities of these emissions vary with the activity, especially the particle precipitations.Transsolo is the kinetic code which solve the transport equation of the electrons along a vertical or a magnetic field line. It allows to obtain the particles fluxes at different energies, angles and altitudes. From this, the code is able to calculate the related emissions.The emission modules have recently been updated by including the vibrational structures of the molecular bands. Several atomic lines have also been added. We can consider that we include more than 95% of the full emission spectra. From this, it is now possible to obtain some almost complete synthetic spectra of the aurora parametrized by the mean energy of the particle fluxes at the top of the atmosphere and the total precipitated energy.Recently Robert et al. show that it is possible to reconstruct the energetic precipitation from the N2+ 427 nm line. However, it remains clear that multiplying the number of considered lines, will allow to get more accurate measurements of these particle fluxes. Moreover, a large number of auroral monitoring instruments are done with filters with variable widths. Such synthetic spectra can help to identify the possible perturbation of the measurements due to wavelength coincidences. For example, the green line at 557 nm is in coincidence with several O2+ and N2 bands in a +/- 5 nm range. Calculating the relative ratio of these lines in different conditions is then crucial.In parallel, we are developing a series of calibrated high sensitivity spectrometers to validate the data and enhance the quality of particle precipitation reconstructions.In this presentation, we will detail the links between these instruments and these synthetic spectra.