Longitudinal variations of nighttime electron auroral precipitation in both the Northern and Southern hemispheres from the TIMED global ultraviolet imager

These features of the auroral longitudinal patterns did not change much from Kp = 1 to Kp = 4 conditions. Since the longitudinal distribution of auroral precipitation changed greatly with season in each hemisphere, the longitudinal variations of the magnetic field strength, which do not change with season, might not be the only process that caused the observed longitudinal variations of the aurora. Further data analysis shows that there was a significant negative correlation (coefficient \r\ = ~0.4 - 0.8) between the peak auroral precipitation intensity and the solar-EUV-produced ionospheric conductivity of the same hemisphere (in summer and equinox) or of the conjugate hemisphere (in winter).

These results indicate the important effects of solar-EUV-produced ionospheric conductivity, which has significant longitudinal variations, on the longitudinal patterns of the aurora at magnetic nighttime. Our results also suggest that the interhemispheric coupling during solstices might be an important factor that contributes to the longitudinal variations of the nighttime aurora. Our correlation analysis indicates that the hemispheric differences in the conjugate magnetic field strengths also contribute to the longitudinal variations of the aurora, although they appear not to be a major factor.