A preliminary dayglow model for summer auroral images from Polar/UVI

Abstract

In this study, we developed a summer dayglow model using auroral emissions acquired by the ultraviolet imager (UVI) onboard the Polar satellite. In the summer polar region, dayglow varies as a cosine-like function of the solar zenith angle (SZA). The shape of this function can be characterized by its amplitude (Amp) and phase (Phi) factors. We first obtained the hourly Amp and Phi factors in summers from 1996 to 2000, and then investigated the universal time (UT) and solar activity variations of these two shape factors. It was found that both factors were non-linearly dependent on the solar flux for all years, and the Amp factor showed clear UT variations under both low and high solar flux years. Thus, a dayglow model was constructed to consider the above dependencies. After the dayglow was removed automatically from the original UVI images via our model, the remaining auroral precipitation energy flux was in good agreement with previously reported magnetic local time–latitude (MLT–MLAT) patterns. Our model provides a fast way to statistically process summer auroral precipitation of Polar/UVI and its variations. Citation: Wang L M, Luan X L. A preliminary dayglow model for summer auroral images from Polar/UVI. Adv Polar Sci, 2016, 27: 272-279, doi: 10.13679/j.advps.2016.4.00272