Analysis of ground and space geoelectric field during geomagnetic storms over Fresno, CA USA: wavelet coherence approach

The solar wind interacts with the earth magnetosphere and ionosphere, causing disturbances that create geoelectric fields in the Earth’s surface. These geoelectric fields link magnetospheric and ionospheric events, affecting the near-Earth environment. In the present study, we analyzed the ground- and space-based geoelectric field over Fresno, California, USA during three geomagnetic storms of different intensities, 19th February 2014 (moderate event), 17th March 2015 (intense event), and 17th March 2016 (weak event). We employed time series analysis and wavelet coherence analysis (WTC) to analyze fluctuations and investigate the strength of association and phase relationship between time series data of geomagnetic storms and geoelectric fields. We observed that ground-based magnetic and electric field fluctuations exhibited a distinct trend compared to space-based observations. WTC indicates that Ey (Space based Electric field) exhibits comparatively more enhanced power regions with solar parameters than EYt (Ground based elecrtic field). This is attributed to the impact of solar winds, which affect the ground electric field but have a less significant effect on the electric field in space.