Solar Coronal Holes Influence Indian Summer Monsoon

February 19, 2025

Recent studies have provided vital information about solar coronal holes and their effects on space weather and the Indian summer monsoon. Coronal holes, identified as dark regions in X-ray and extreme ultraviolet images of the Sun, are characterised by open magnetic field lines. These features play important role in understanding the interplanetary medium and the dynamics of space weather.

About Coronal Holes

Coronal holes are low-density areas on the Sun’s surface.
Discovered in the 1970s, they are sources of fast solar wind that can reach speeds between 450 to 800 km/sec.
The open magnetic field lines in these regions allow charged particles to escape more freely into space.
This high-speed solar wind can interact with the Earth’s magnetic field, causing geomagnetic storms and other disturbances.

Influence on Space Weather

The interaction between solar wind and the Earth’s magnetic field can lead to various space weather phenomena. Geomagnetic storms can disrupt satellite operations and affect communication systems. The disturbances also impact the Earth’s ionosphere, which is crucial for radio wave propagation.

Coronal Holes and Monsoon Rainfall

Recent research indicates that coronal holes may also influence the Indian summer monsoon. A physics-based study suggests that the radiative effects of coronal holes, alongside the well-known influence of sunspots, contribute to the variability of monsoon rainfall. Understanding these influences is essential for predicting weather patterns.

Thermal and Magnetic Field Structures

The thermal and magnetic field structures of coronal holes have now been characterised in detail. Researchers from the Indian Institute of Astrophysics used eight years of data from the Solar and Heliospheric Observatory (SOHO). They found no latitudinal variation in the temperature structure of coronal holes. However, they observed that the strength of the magnetic field increases from the solar equator towards the poles.

Research Findings

The study revealed two findings. Firstly, the consistent temperature structure suggests that coronal holes likely originate from the Sun’s deep interior. Secondly, the increasing magnetic field strength indicates that coronal holes may be formed through the superposition of Alfven wave perturbations. These findings provide a deeper understanding of the formation and evolution of coronal holes.

Importance of Continued Research

As the effects of space weather become increasingly relevant, ongoing research into coronal holes is vital. About their thermal and magnetic properties can enhance predictions of their impact on Earth. This knowledge is crucial for safeguarding satellite operations and improving weather forecasting.

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