Modulation of the dayside diffuse auroral intensity by the solar wind dynamic pressure

摘要

abstract_textpCompared to the recently improved understanding of the nightside diffuse aurora, the mechanism(s) responsible for the dayside diffuse auroral precipitation remains limitedly understood. We investigate the dayside diffuse aurora observed by the all-sky imagers of Chinese Arctic Yellow River Station in the time interval of 02:00-10:00 UT (05:00-13:00 magnetic local time) on 2 January 2006. In this interval, the intensity of dayside diffuse aurora is highly correlated with the solar wind dynamic pressure with a maximum coefficient of 0.89. Moreover, there are similar spectra characteristics in the Pc5 range between the intensity of dayside diffuse aurora and solar wind dynamic pressure (proton density) during a portion of the time interval, in which the interplanetary magnetic field Bz is northward. The observation indicates that changes in solar wind dynamic pressure can efficiently modulate the magnitude of the dayside diffuse aurora, except when the interplanetary magnetic field is southward. The enhancement of the solar wind dynamic pressure can provide favorable circumstances for dayside chorus wave generation, so we consider that the dayside chorus could be a candidate for the production of the dayside diffuse aurora. Furthermore, since the compressional Pc4-Pc5 pulsations can also modulate the intensity of whistler mode chorus waves, the solar wind dynamic pressure modulates the dayside diffuse aurora through affecting dayside chorus wave activity and the associated scattering process./p/abstract_text