Short timescale variations in ionosphere caused by irregular solar electromagnetic radiation

Solar activity dependency of the ionosphere in local region during a short timescale is of great importance for the analysis of ionospheric anomalies probably caused by local events such as earthquakes and volcanic eruptions. Recently, a nonlinear background removal method based on multiresolution wavelet transform (MWT) for seismo-ionospheric anomaly analysis has been developed by He et al. To further evaluate the method performance, three years of different solar activity levels have been chosen to examine the relationship between the TEC variations and solar activities during 23rd solar cycle. The results showed that the MWT-based method is able to handle well the solar radiation background in the ionospheric TEC data, especially under a complex solar activity situation.