DP2 Magnetic Disturbances : A Part from the Book Chapter : The Solar Wind Impact on Magnetosphere and Identification of the IMF by Component with Use of the Ground-Based Magnetic Data

System of ionospheric currents responsible for DP2 magnetic disturbances, consists of two vortices, roughly symmetrical relative to the Sun-Earth line, with the sunward-directed currents in the central polar cap, the current focuses being located in the morning and evening sectors of the auroral zone poleward boundary. Multi-functional analysis of relationships between the polar cap magnetic disturbances and the IMF variations, representing the combination of radial (BX), azimuthal (BY) and vertical (BZ) IMF components changes, has revealed  existence of DP0 magnetic disturbances, similar to DP2, but independent on IMF. Taking into account the evident similarity of DP2 and DP0 disturbances, which are distinguished only by power of disturbances and, correspondingly, by the intensity of currents, the conclusion was made that DP2 and DP0 disturbances are generated by the same current system, the intensity of currents being regulated by southward IMF component. It was shown subsequently that DP0 disturbances are controlled by the solar wind velocity.

Author(s) Details:

 A. Troshichev

Arctic and Antarctic Research Institute, Russia.


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Recent global research developments in Ionospheric Currents and DP2/DP0 Magnetic Disturbances

1. Middle Latitude Geomagnetic Disturbances Caused by Hall and Pedersen Current Circuits Driven by Prompt Penetration Electric Fields:

  • This study [1] investigates the prompt penetration electric field (PPEF) that drives the DP2 currents. These currents consist of two-cell Hall current vortices surrounding the Region-1 field-aligned currents (R1FACs) and the zonal equatorial electrojet (EEJ, also known as the Cowling current) at the dayside equator. The Pedersen currents at middle latitudes connect the EEJ to the R1FACs.
  • The midlatitude H- and D-components of the disturbance magnetic field are caused by the DP2 currents, as well as by other magnetospheric currents (e.g., magnetopause currents, FACs, ring currents).
  • The study analyzes 39 DP2 events in the morning and 34 events in the afternoon from magnetometer data at Paratunka, Russia. These events exhibit a negative H-D correlation, suggesting that H and D are caused by the Hall and Pedersen currents, respectively.
  • The midlatitude H/D is highly correlated with the EEJ at Yap, Micronesia, confirming the Pedersen–Cowling current circuit between midlatitude and equator in the DP2 current system.

2.Response of the Equatorial Ionosphere to the Geomagnetic DP2 Current:

  • While this paper [2]focuses on high-latitude geomagnetic disturbances, it mentions the DP2 current system associated with magnetospheric convection. The DP2 current (disturbance polar of the second type) is directly related to substorm westward electrojet disturbances.

3.Impact of June 2015 Geomagnetic Disturbances on the Brazilian Longitudinal Sector:

  • In this study [3], the effect of geomagnetic disturbances on the Brazilian longitudinal sector is examined. The DP2 current fluctuations from the ionospheric electric current disturbance are considered.

References

  1. Kikuchi T, Hashimoto KK, Tanaka T, Nishimura Y, Nagatsuma T. Middle Latitude Geomagnetic Disturbances Caused by Hall and Pedersen Current Circuits Driven by Prompt Penetration Electric Fields. Atmosphere. 2022; 13(4):580. https://doi.org/10.3390/atmos13040580
  2. Yizengaw, E., Moldwin, M. B., Zesta, E., Magoun, M., Pradipta, R., Biouele, C. M., … & De Paula, E. R. (2016). Response of the equatorial ionosphere to the geomagnetic DP 2 current system. Geophysical Research Letters, 43(14), 7364-7372.
  3. Afolabi OO, Candido CMN, Becker-Guedes F, Amory-Mazaudier C. Study and Modelling of the Impact of June 2015 Geomagnetic Storms on the Brazilian Ionosphere. Atmosphere. 2024; 15(5):597. https://doi.org/10.3390/atmos15050597

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