GEOMAGNETIC PEARL OSCILLATIONS

  • 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.
  • 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.

About the Geomagnetic Pc1 pearl oscillations:

  • 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.
  • At very low latitude stations, it is not frequent.
  • These waves are an important component of space weather in the near-Earth environment.

Findings of the study:

  • A clear increase in the number of Pc1 at night was observed compared to the day.
  • This is because the attenuation of Pc1 waves upon propagation via the ionospheric waveguide towards lower latitudes is weaker during night hours.
  • Similarly, during the solar maximum period, the transmission rate of Pc1 waves to the equator was diminished than during the solar minimum.
  • The annual and seasonal patterns of Pc1 occurrence showed an inverse relation with sunspot numbers at both stations.
  • An association of these pulsations with active geomagnetic conditions showed the occurrence of Pc1 increasing significantly in the recovery phase of geomagnetic storms.

SOURCE: THE HINDU, THE ECONOMIC TIMES, PIB

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