For lower and middle latitude stations, Chapman (1927) concluded that the average characteristics of slight and intense disturbances are similar in type. Thus, the average storm-time effect on the horizontal force should decrease the daily mean during the disturbance. A period of recovery then follows and lasts for several days. This is followed by a decrease of much greater amplitude, which lasts for several hours. Regarding the geomagnetic field, Chapman (1918) pointed out that the net mean changes in the horizontal component during the first half-hour or so of a geomagnetic storm is an increase. (1994), moderate geomagnetic storms are characterized by the thresholds of –50 nT, –5 nT, and 2 hours for the Dst index, IMF- Bz, and interval, respectively. Space storms are global geomagnetic disturbances that result from the interaction between magnetized plasma that propagates from the Sun and plasma and magnetic fields in the near-Earth space plasma environment (Wanliss and Showalter, 2006). Solar-surface magnetic variability, solar flares, sunspots, coronal activities, and their interplanetary transients can be related to the appearance of solar activity (Tsurutani et al., 2006). This work connects the interplanetary plasma parameters to the storm-time geomagnetic variations. Further, variation of solar wind parameters indicated geomagnetic storms are guided by the prolonged southward IMF- Bz component and highly fluctuated IMF- By component. The magnitude of the Y-component was significantly reduced during the main phase in comparison to the quiet days.
We found a positive correlation between Y-component and the SYM-H index for both events. We have used solar wind velocity, pressure, and interplanetary magnetic fields ( By and Bz) to know the interplanetary structure for the selected duration. We investigated the correlation of the Y-component with geomagnetic index SYM-H using wavelet multiresolution analysis. The magnetogram data recorded on low latitude stations are used for the study. This work analyzes the Y-component of the geomagnetic field during two geomagnetic storms and compares it to the solar quiet days. Electrodynamical coupling between the solar wind’s plasma and the Earth’s magnetosphere creates geomagnetic disturbances recorded on the ground.