Researchers have traced a very significant increase in special continuous oscillations with pearl-type structures called Geomagnetic Pc1 pearl oscillations on the surface of the Earth in the recovery phase of geomagnetic storms. This study is significant for investigating of precipitation particles during geomagnetic storms and can help us understand the radiation hazard to satellites and astronauts.
Earth’s magnetic field forms a protective shield around us, and various plasma waves are generated in this magnetic field cavity. However, geomagnetic storms often cause a dent in this protection. Energetic particles are either accelerated or lost from the Earth’s radiation belts during these storms. This is responsible for changes in plasma environment leading to growth of low-frequency waves called Electromagnetic ion-cyclotron (EMIC) wave instability which is seen as the magnetic field oscillations (0.1-5 Hz) called as Pc1 pulsations.
The Geomagnetic Pc1 pearl oscillations are amplitude-modulated structured narrow-band signals, which are signatures of low-frequency EMIC waves generated by resonant wave-particle interactions in the Earth’s magnetosphere. The observation of these oscillations is a proxy for the measurement of particle precipitation in the Earth’s magnetosphere.
Evidences of these pulsations are abundant in the mid and high-latitude regions. However, at very low latitude stations, it is not frequent. These waves are an important component of space weather in the near-Earth environment.
A team of scientists at IIG, an autonomous institute of the Department of Science and Technology, along with different Indian and global organization investigated the long-term variability of these pulsations in connection to solar cycles 20-21 and descending phase of solar cycle 24 from very low latitude regions of India.