The results of GAIA simulations on May 13, 2013. The left figure shows the difference in the ion production rates between before the flare began (1:45 UT) and at the flare peak (2:15 UT). The right figure shows the electron density distributions. The dashed line is the electron density at 1:45 UT, the solid line is that at 2:15 UT, and the dotted line is that at the end of the SWF (3:45 UT).