Study of Geomagnetic Field Response to Solar Wind Forcing

The solar wind is an integral component of space weather that has a huge impact on the near-Earth space conditions, which can in turn adversely impact technological infrastructure. By analyzing solar wind data, we can investigate the response of the Earth's magnetic field to changes in solar wind conditions, such as dynamic pressure, speed, and interplanetary magnetic fields (IMF). When a coronal mass ejection (CME) hits the Earth's magnetosphere, it compresses the dayside magnetosphere, which leads to SSC (Sudden Storm Commencement) seen in Dst or SYM-H index. Dst and SYM-H index are a measure of geomagnetic storm intensity that represents the magnetic field perturbations in the equatorial region originating from ring current. In this study, we focused on SSC intervals with sudden density increase, density, greater than 10 n/cc from 2000 to 2015 using data obtained from the NASA CDAWEB service. A total of 1,049 events were picked for this project. Then using INTERMAGNET service, corresponding horizontal component of magnetic field data were collected from several stations located in equatorial region, mid-latitude region, high-latitude region on the day-side and night-side of Earth. Using MATLAB, we calculated the rate of change of magnetic fields (dB/dt) for each station and each event. We found that in most cases, the sudden increase in proton density is associated with large changes in magnetic fields, dB/dt. The largest magnetic field changes were observed on the day-side than night-side at high latitudes. Interestingly, some exceptions were found such that greater dB/dt was found on night-side than day-side during some events, particularly at high latitudes. We suspect these are driven by magnetospheric substorms, which are manifested by an explosive release of energy in the local midnight sector. The next step will be creating the statistical form to see the correlation between proton density changes and magnetic field changes.