Impact of model differences on quantitative analysis of FUV auroral emissions: Total ionization cross sections

A sensitivity study was performed in which the peak height of modeled FUV a uroral emissions was displaced in altitude, an effect that can result from several causes in the modeling process. The purpose of the study was to exa mine the impact of such displacements on energy parameters extracted from F UV auroral observations. For this study, the Nz total ionization cross sect ion was modified above 1 keV. Cross-sectional modifications are investigate d for a variety of reasons including the fact that they can directly impact modeled emission height profiles and because different cross-section sets are adopted by different modelers. Though physically unrealistic, the magni tude of the change in cross section considered here is large enough that th is study covers the expected range of uncertainties within a single model o r between two or more different models. The values reported here can thus b e viewed as upper limits for these uncertainties. The high-energy modificat ions result in changes of up to 3 km in the altitude of peak emission for F UV emissions excited by 10-keV electrons. For calculations using data from the Polar Ultraviolet Imager, derived energy flux and mean energy are chang ed by up to 16% and 23%, respectively, for 10-keV incident electrons.