OBSERVATION AND ANALYSIS OF NI 520.0 NM AURORAL EMISSIONS

The results from the analysis of simultaneous auroral ground-based opt ical measurements of the N(D-2) 520.0 nm, N-2(+) 1NG 470.9 nm, O(P-3) 844.6 nm and the O(D-1) 630.0 nm emission intensities are presented. T he data were obtained during auroral observations at Gillam (56.35 deg rees N, 265.32 degrees E) over an observation period of about 8 hours, from UT 2:33 hrs to UT 10:06 hrs, on 20 March 1985. The soft electron flux measurements on board the DMSP satellite for the time of the exp eriment have also been considered in the analysis. The N(D-2) density and the N(D-2) 520.0 nm integral emission rate I(520.0) were calculate d employing a one- and two-dimensional time-dependent ion-chemistry mo del and the model predictions have been compared with the experimental I(520.0) nm emission rates. It was found that the model predictions o f the NI I(520.0) nm intensity based on the electron energy fluxes inf erred from the experimental I(844.6)/I(427.8) emission rate ratios are smaller in magnitude than the experimental values by a factor of 5-8 after allowing for horizontal transport of [N(D-2)] by neutral winds. Assuming soft electron precipitation, suggested by the OI I(630.0) nm emission measurements and the DMSP satellite electron flux data, provi ded good agreement between the model and experimental results. Based o n the results obtained it was concluded that horizontal transport play ed a minor role and that the observed N(2D) I(520.0) nm emissions were mostly produced by precipitating soft electron fluxes with energies b elow about 100 eV.