A Study On Visible Characteristics Of 'Bright Spots', Auroras

Aurora Ovals are elliptical zones which produced by Aurora, the centered by polars magnetic in Arctic and Antarctica. Along the Aurora Ovals, there are some important regions of particles precipitating: Aurora Subtrom (2200MLT), 1500MLT Hot Spot, 0900MLT and Midday Peaks."Bright Spots" is an ultraviolet auroral form along the post-noon oval which is first found by Viking Satellite launched in the end of 80's. They appear a sequence of regularly distributed spots along post-noon Aurora Oval, with the size of about 50~200km. Lui et al. attributed this phenomena as Kelvin-Helmholtz Instability in LLBL. However, shown that particles precipitating detected by satellites, the particles are come from Plasma Boundary Layer. Because of strong components in Sun Spectrum, there has been no report on satellite of the visible observation of Bright Spots.Because of the Ozone absorption against UV lights, none observation of auroras is made in UV range on the ground. By the conjugacy of auroral particles precipitating in Bi-Hemispheres, and the season's difference of sunlight between North-South Hemisphere, we found and analyzed some cases of bright spots, which were observed simultaneously by all-sky camera at Zhongshan in the Antarctica and the UV imagery aboard the POLAR satellite covering the Arctic. The visible features of 'bright spots' aurora is found to be relates with spire structure along auroral arc in southerly hemisphere. The spires are lighter than other parts in the arc, moving to East or West along the arc, and short-lived about 1 min.