Heliospheric Structures & Space Weather

Research Overview

My research investigates the magnetic structure, plasma dynamics, and evolution of large-scale heliospheric disturbances, particularly interplanetary coronal mass ejections (ICMEs), their sheath regions and magnetic obstacles, and stream interaction regions. These structures undergo compression, deformation, and interactions with the ambient solar wind, producing complex magnetic configurations, turbulent fluctuations, and changes in plasma thermodynamics. Using in situ observations from Wind, ACE, and Parker Solar Probe, I study the morphology and internal properties of interplanetary magnetic structures, including planar magnetic structures, magnetic flux ropes, and Alfvénic fluctuations. My work examines how these features develop, interact with the surrounding plasma, and influence the evolution and geoeffectiveness of heliospheric disturbances.

A broader goal of my research is to connect the structural evolution of interplanetary disturbances with solar-wind turbulence, plasma energy transport, and solar–terrestrial interactions.

Key Scientific Questions

ICME morphology and evolution: How do magnetic obstacles deform and evolve during their propagation through the heliosphere, and what plasma conditions favour the development of planar magnetic structures?

ICME sheath dynamics: How do magnetic compression, field draping, and turbulent fluctuations influence the formation and properties of coherent magnetic structures within ICME sheaths?

Alfvénic fluctuations and magnetic structures: How do Alfvén waves coexist and interact with planar magnetic structures and magnetic flux ropes in interplanetary plasma environments?

Solar-wind turbulence near the Sun: What are the spectral and magnetic properties of turbulence within small-scale magnetic flux ropes, and how do they relate to the surrounding solar wind?

Plasma thermodynamics: How do heating, cooling, expansion, and compression influence the thermodynamic evolution of ICME magnetic obstacles?

Geomagnetic activity: How do the internal magnetic configurations and Alfvénic fluctuations of ICMEs influence the development and recovery of geomagnetic storms?

Selected Scientific Contributions

Planar Magnetic Structures and Alfvén Waves in ICME Sheaths

My research has investigated the coexistence of coherent magnetic structures and Alfvénic fluctuations within highly compressed ICME sheath regions. In Shaikh et al. (2019, MNRAS), we identified a shock–sheath interval exhibiting simultaneous characteristics of a planar magnetic structure and an Alfvén wave. Using magnetic-field analysis and the Walén test, the study provided observational evidence of the coexistence of these features. Extending this investigation, Shaikh et al. (2020, MNRAS) conducted a statistical analysis of 420 ICME sheath regions observed by ACE. We identified planar magnetic structures in approximately 35% of the events and found that planar sheaths generally exhibit stronger magnetic fields, higher plasma compression, and enhanced plasma parameters compared with non-planar sheaths.

Morphology and Plasma Properties of ICME Magnetic Clouds

My research has examined the structural deformation and magnetic configuration of ICME magnetic clouds during their evolution through interplanetary space. In Shaikh & Raghav (2022, ApJ), we investigated 469 ICMEs observed at 1 au and identified planar magnetic configurations in approximately 29% of the events. Compared with non-planar structures, planar ICMEs showed stronger magnetic fields, enhanced plasma compression, and smaller thicknesses. These findings provide statistical observational evidence of the role of compression in modifying the morphology of interplanetary magnetic structures.

Solar-Wind Turbulence within Small-Scale Magnetic Flux Ropes

Using Parker Solar Probe observations, my research has investigated the turbulent properties of small-scale magnetic flux ropes in the inner heliosphere. In Shaikh et al. (2023, ApJ), we analysed 50 small-scale magnetic flux ropes observed during the first three Parker Solar Probe encounters. The magnetic fluctuations exhibited a mean spectral index of −1.49 ± 0.21, low magnetic compressibility, and signatures consistent with predominantly Alfvénic turbulence. These observations provide constraints on the nature of turbulent fluctuations and the transfer of magnetic fluctuation energy within coherent solar-wind structures close to the Sun.

Thermodynamic Evolution of ICME Magnetic Obstacles

I have also investigated the thermodynamic behaviour of ICME magnetic obstacles using long-term ACE spacecraft observations. In Shaikh et al. (2025, A&A), we examined 473 ICME magnetic obstacles and identified 25 events exhibiting super-adiabatic proton behaviour, with a mean polytropic index of 2.14 ± 0.07. The study also identified populations exhibiting approximately isothermal and adiabatic behaviour. These findings indicate that ICME magnetic obstacles can experience different thermal evolution regimes, providing observational constraints on plasma cooling and energy exchange during their propagation.

Magnetic Structures and Geomagnetic Storms

My research has examined the relationship between the internal magnetic structures of ICMEs and the temporal evolution of geomagnetic storms. In Shaikh et al. (2019, MNRAS), we investigated a geomagnetic storm with multiple main and recovery phases, identifying different responses associated with planar magnetic structures and Alfvénic fluctuations. The observations showed relatively rapid decreases and recoveries of geomagnetic activity during the passage of planar structures, whereas intervals containing Alfvénic fluctuations were associated with more gradual variations. These results demonstrate how embedded magnetic structures can influence different phases of geomagnetic disturbances.

Representative Scientific Figures

Related Publications

1. Shaikh, Z. I., Raghav, A., & Vichare, G. (2019). Coexistence of a Planar Magnetic Structure and an Alfvén Wave in the Shock-Sheath of an Interplanetary Coronal Mass Ejection. Monthly Notices of the Royal Astronomical Society, 490, 1638–1643. DOI

2. Shaikh, Z. I., et al. (2019). Concurrent Effect of Alfvén Waves and Planar Magnetic Structure on Geomagnetic Storms. Monthly Notices of the Royal Astronomical Society, 490, 3440–3447. DOI

3. Shaikh, Z. I., et al. (2020). Comparative Statistical Study of Characteristics of Plasma in Planar and Non-Planar ICME Sheaths during Solar Cycles 23 and 24. Monthly Notices of the Royal Astronomical Society, 494, 2498–2508. DOI

4. Shaikh, Z. I., & Raghav, A. N. (2022). Statistical Plasma Properties of the Planar and Nonplanar ICME Magnetic Clouds during Solar Cycles 23 and 24. The Astrophysical Journal, 938, 146. DOI

5. Shaikh, Z. I., et al. (2023). Nature of Turbulence inside Small-scale Magnetic Flux Ropes near the Sun: Parker Solar Probe Observations. The Astrophysical Journal, 959, 50. DOI

6. Shaikh, Z. I., et al. (2025). Revealing Super-Adiabatic Features of Interplanetary Coronal Mass Ejections at 1 au. Astronomy & Astrophysics, 693, L12. DOI

Current and Future Research Directions

My ongoing and future research seeks to investigate the evolution of heliospheric structures by connecting large-scale magnetic configurations with plasma turbulence, coherent structures, and energy transfer using multi-spacecraft observations and comparisons with numerical simulations.

Turbulence within interplanetary structures: Investigating the evolution of magnetic power spectra, intermittency, and characteristic turbulent scales across ICME sheath regions and magnetic obstacles using Wind and Solar Orbiter observations.

Evolution of coherent magnetic structures: Examining the formation, deformation, and statistical properties of magnetic flux ropes, current sheets, and discontinuities within different heliospheric plasma environments.

Shock–turbulence interactions: Investigating how interplanetary and planetary collisionless shocks modify upstream magnetic fluctuations, turbulent spectra, and coherent structures.

Thermodynamics of expanding plasma structures: Extending observational investigations of heating, cooling, and polytropic behaviour to understand the thermal evolution of interplanetary plasma structures across heliocentric distances.

Heliospheric dynamics and space-weather connections: Examining how magnetic-field configurations, turbulent fluctuations, and coherent structures influence the interaction of solar-wind disturbances with Earth's magnetosphere.

These investigations aim to connect the large-scale evolution of heliospheric disturbances with the turbulent and structural properties of magnetised space plasmas.