Plasma flux and gravity waves in the midlatitude ionosphere during the solar eclipse of 20 May 2012

The solar eclipse effects on the ionosphere are very complex. Except for the ionization decay due to the decrease of the photochemical process, the couplings of matter and energy between the ionosphere and the regions above and below will introduce much more disturbances. Five ionosondes in the Northeast Asia were used to record the midlatitude ionospheric responses to the solar eclipse of 20 May 2012. The latitude dependence of the eclipse lag was studied first. The f(o)F(2) response to the eclipse became slower with increased latitude. The response of the ionosphere at the different latitudes with the same eclipse obscuration differed from each other greatly. The plasma flux from the protonsphere was possibly produced by the rapid temperature drop in the lunar shadow to make up the ionization loss. The greater downward plasma flux was generated at higher latitude with larger dip angle and delayed the ionospheric response later. The waves in the f(o)E(s) and the plasma frequency at the fixed height in the F layer are studied by the time period analytic method. The gravity waves of 43-51min center period during and after the solar eclipse were found over Jeju and I-Cheon. The northward group velocity component of the gravity waves was estimated as 108.7m/s. The vertical group velocities between 100 and 150km height over the two stations were calculated as 5 and 4.3m/s upward respectively, indicating that the eclipse-induced gravity waves propagated from below the ionosphere.