Common solar wind drivers behind magnetic storm-magnetospheric substorm dependency.

Area of Science:

• Space physics
• Geophysics
• Solar-terrestrial physics

Background:

• The relationship between magnetic storms and magnetospheric substorms is a long-standing debate in space research.
• Understanding this connection is crucial for space weather prediction and understanding magnetospheric dynamics.

Purpose of the Study:

• To investigate the causal relationship between magnetic storms and magnetospheric substorms.
• To identify the primary drivers of both phenomena using a causal inference approach.

Main Methods:

• Causal inference analysis applied to geomagnetic indices.
• Statistical analysis of time series data for solar wind variables and geomagnetic indices.
• Investigated the vertical component of the interplanetary magnetic field (IMF BZ) as a potential driver.

Main Results:

• The vertical component of the interplanetary magnetic field (IMF BZ) was identified as the strongest common driver for both magnetic storms and substorms.
• No statistical evidence was found for a direct or indirect causal dependency between substorms and storms.
• The observed statistical association between storms and substorms can be attributed to shared solar drivers.

Conclusions:

• A direct or indirect physical mechanism driving storms from substorms, or vice versa, is unlikely based on the analyzed data and statistical tests.
• The interplanetary magnetic field's vertical component is a key factor influencing both geomagnetic phenomena.
• Future research should consider the role of common solar drivers in explaining the co-occurrence of storms and substorms.