When the satellite experiments revealed the field-aligned currents (FAC) acting in the magnetosphere, it became evident that the different polar cap magnetic disturbances are generated by various FAC systems. The main R1 FAC system, permanently operating within magnetosphere, produces the polar cap DP2 magnetic disturbances irrespective of season and IMF polarity. The field-aligned current systems, operating in the polar magnetosphere under conditions of the BZN and BY IMF components influence, named as NBZ and BY FAC systems, generate corresponding DP3 and DP4 disturbances. Dependence the BY FAC and appropriate DP4 disturbances on polarity of the BY IMF component is opposite in the northern and southern polar regions. The DP3 and DP4 disturbances are typical of summer polar cap, where high conductivity of the sun-lit ionosphere provides the best conditions for closure of the NBZ and BY FAC systems.
Taking into account that the DP2 disturbances are related to southward IMF as well as magnetic storms and substorms, the suggestion was made that the polar cap magnetic activity can serve as a signature of substorm development. As Fig. 1b shows, the DP2 sunward currents in the central polar cap generate the magnetic disturbances of dawn-dusk orientation. Just value of these duskward-directed magnetic disturbances (i.e. projection of the magnetic disturbance vector δF on the dawn-dask axis) was examined, when the correlation between the DP2 disturbances and different solar wind parameters (coupling functions) was examined. Results of the analysis have demonstrated that polar DP2 disturbances well correlates with various “coupling functions”, used for description of the solar wind – magnetosphere coupling, but the best correlation is observed with function EKL = VSWBTsin2(θ/2) [30], where θ is angle between the geomagnetic dipole and the IMF tangential component BT = (BY2 + BZ2)1/2.
Author(s) Details:
A. Troshichev
Arctic and Antarctic Research Institute, Russia.
Recent global research developments in Solar Wind Impact on Magnetosphere and IMF BY Identification with Ground-Based Magnetic Data
A Dynamic PCA and Machine Learning Tool for Automated Identification of Solar Wind Disturbances Impacting Earth’s Magnetosphere:
- Researchers have developed a generic method for automated anomaly detection in magnetic field measurements based on dimensionality reduction and unsupervised clustering via machine learning [1]. This technique allows for the identification of various solar wind disturbances impacting the magnetosphere, including shocks, discontinuities, and magnetic clouds.
- The benefit of this approach lies in its high degree of generalizability and flexibility, making it useful for a wide range of magnetic field datasets. Additionally, it can be applied to other observed time-series properties (such as plasma density, pressure, and velocity) for more accurate event identification.
- The method has been evaluated using data from Magnetospheric MultiScale (MMS) and THEMIS-ARTEMIS missions, providing insights into future platforms like the Heliophysics Environmental and Radiation Measurement Experiment Suite (HERMES) instruments that will measure solar wind and IMF properties from lunar orbit onboard the Gateway station.
Global Magnetosphere Response to Solar Wind Dynamic Pressure Pulses:
- This study combines solar wind data from ACE and WIND spacecraft with magnetic field observations from various missions (Geotail, Cluster, THEMIS, MMS, Van Allen Probes, GOES) and ground magnetometer arrays [2]. By observing the magnetosphere and ionosphere response simultaneously, researchers gain insights into different local time sectors and regions.
- The focus is on understanding how rapid increases in solar wind dynamic pressure affect the magnetosphere and its various domains (dayside, nightside, inner magnetosphere, magnetotail, magnetosheath).
Geomagnetic Response to Rapid Increases in Solar Wind:
- Another study uses the random forest machine learning algorithm to detect discontinuities in situ solar wind data. These detected events are then propagated to Earth, and their arrival times are aligned with corresponding responses in the low-latitude ground magnetic field [3].
- This approach provides valuable information about the impact of solar wind disturbances on Earth’s magnetosphere and ionosphere.
References
- Martinez-Ledesma, M., Finley, M., Zesta, E., Paterson, W. R., & Dorelli, J. (2023, December). A Dynamic PCA and Machine Learning Tool for Automated Identification of Solar Wind Disturbances Impacting Earth’s Magnetosphere. In 23rd Meeting of the American Geophysical Union (AGU). https://ntrs.nasa.gov/citations/20240001031
- Vidal‐Luengo, S. E., & Moldwin, M. B. (2021). Global magnetosphere response to solar wind dynamic pressure pulses during northward IMF using the heliophysics system observatory. Journal of Geophysical Research: Space Physics, 126(2), e2020JA028587.
- Madelaire M, Laundal KM, Reistad JP, Hatch SM, Ohma A and Haaland S (2022) Geomagnetic Response to Rapid Increases in Solar Wind Dynamic Pressure: Event Detection and Large Scale Response. Front. Astron. Space Sci. 9:904620. doi: 10.3389/fspas.2022.904620
