Low latitude Pi2 pulsations at Desalpar, Gujarat, India: A statistical analysis of the influences of magnetic storms/substorms, seasons, and solar cycles

Abstract

In this paper, we investigate the characteristics of geomagnetic pulsations (Pi2) using ground magnetometer data from the Induction Coil Magnetometer of Desalpar, Kachchh, Gujarat, India. We report here the morphology of Pi2 bursts (6–25 mHz) and their local temporal variations over the period of 2013–2017. The investigation is being conducted to study the effects of Sun-Earth interaction on the occurrences of low-latitude Pi2 pulsations. Local trend analysis was performed by classifying the data into 3 h local time slots (LT = UT+5.5). The Pi2 periods and the frequency of occurrence in local time in 2013 show that the maximum number of events occurs in the early morning and at midnight, and a very small number of events in the middle of the day. This could be due to tail currents at magnetic reconnection during the night-time. We have observed more events in the Y component compared to the X component. On the other hand, the observed periods of the X component are longer compared to the Y component. Enhanced periodicity of Pi2 observed during 18.0–19.0 LT. The periodicity of the H component is increased from 6.0 LT and reaches a maximum during 18.0–19.0 LT and then decreases. The maximum amplitude is noted at 6.0 LT. The amplitude of the Y component noticed is the largest than the X component during the study period. Number of Pi2s are found different in different ranges of Kp, Interplanetary Magnetic Field (IMF) and Solar wind speed (SWS), Proton density (PD) with maximum number in lower Kp values, IMF B~5 nT, SWS~400 Km/s, PD~5–10N/cc. The identified peak-to-peak amplitudes of Pi2s are in relation with the generated plasma dynamics of magnetosphere by the solar parameters as various global parameters such as the IMF, interplanetary electric field (IEy), sunspots numbers (SSN), planetary index (Kp), SWS, PD, and Bursty Bulk Flows (BBFs) generated Pi2s have been noted during midnight (18.0–21.0 UT and 3.0–9.0 UT) during the 2013–2015 compared to the 2016–2017. This is evident with the longer period of Pi2s greater than 120 Sec. These longer period Pi2s have been accompanied with the field aligned currents produced by braking BBFs. The winter and fall seasons showed a good substantial generated Pi2s in our study compared to other seasons. We found an inverse relationship of occurrence of Pi2 is with global parameters such as SSN, Kp and IEy on our site. 74–78% of Pi2s generated is during the substorm period. The non-substorm Pi2s seems to be more in 2013–2015 (Solar maximum) than in 2016–2017 (Solar minimum).