Analysis of the Consecutive X‐Ray Flares Effects on the Lower Ionosphere

Abstract X‐ray is a critical factor in generating electrons in the lower ionosphere, however, the cumulative effects of consecutive X‐ray flares on the lower ionosphere remain understudied due to the scarcity of historical events. From May 8 to 15, 2024, intense solar eruptions occurred, featuring multiple consecutive X‐ray flares. By leveraging data from space‐based satellites and ground‐based ionosondes during these consecutive X‐ray flare events, we investigate the correlations between extreme ultraviolet (EUV) radiation, soft X‐rays, hard X‐rays, solar energetic proton fluxes and ionospheric parameters (minimum reflection frequency and E‐layer critical frequency). And then we analyze the physical mechanisms governing the lower ionosphere's response to consecutive X‐ray flares. The key findings include: Consecutive X‐ray flares consistently induced significant responses in the dayside lower ionosphere; When two consecutive X‐ray flares occur very close together, then the previous X‐ray ionization will reduce the effect of the subsequent X‐ray flare on the ionospheric electron density increase; High‐energy protons can directly penetrating Earth's magnetic field to trigger intense ionospheric responses; X‐ray flare effects on the lower ionosphere typically lasted about 1 hr, however, when accompanied by solar proton events, subsequent high‐energy protons could compound with later X‐ray flares to produce cumulative effects.