Massive holes in the sun affect Indian monsoons

Coronal holes across the sun can influence India’s monsoon rains. These holes release high-speed solar wind, which interacts with Earth’s magnetic field, potentially affecting rainfall patterns, according to a recent study.

An India Today report highlights this new study, published in the journal Astronomy and Astrophysics, which has accurately estimated the physical parameters of thermal and magnetic field structures within solar coronal holes, which have a significant influence on space weather and the Indian summer monsoon rainfall. These findings are crucial, as space weather affects satellites, and there is growing evidence linking coronal holes to variations in the Indian Monsoon rainfall.

Astronomers from the Indian Institute of Astrophysics (IIA) in this study have now accurately characterised the latitude dependence of temperature and magnetic field strengths within these coronal holes. The study examined coronal holes – dark regions observed in X-ray and extreme ultraviolet images of the Sun – that are characterised by open magnetic field lines, making them essential for understanding the interplanetary medium, the India Today report points out. Based on eight years of solar data, the study suggests that these solar changes could help improve monsoon predictions. This discovery is crucial for farmers, disaster management, and climate researchers, as better forecasting can help prepare for droughts or heavy rains.

As explained by the National Oceanic and Atmospheric Administration (NOAA), coronal holes appear as dark areas in the solar corona in extreme ultraviolet (EUV) and soft x-ray solar images. They appear dark because they are cooler, less dense regions than the surrounding plasma and are regions of open, unipolar magnetic fields. This open, magnetic field line structure allows the solar wind to escape more readily into space, resulting in streams of relatively fast solar wind and is often referred to as a high speed stream in the context of analysis of structures in interplanetary space. Coronal holes can develop at any time and location on the Sun but are more common and persistent during the years around solar minimum. The more persistent coronal holes can sometimes last through several solar rotations (27-day periods). Coronal holes are most prevalent and stable at the solar north and south poles; but these polar holes can grow and expand to lower solar latitudes.

In early February, according to a Fox Weather report, NOAA Space Weather Prediction Center forecasters were monitoring two coronal holes on the Sun for space weather impacts on Earth. They were monitoring the larger coronal hole in the Northern Hemisphere and a smaller, narrower hole in the Southern Hemisphere. These dark areas on the Sun, as seen in satellite images, can produce space weather events known as coronal hole high-speed streams, which can trigger Northern Lights on earth. Depending on where the coronal hole is located, it can impact what we experience on earth. A coronal hole high-speed stream produces increased solar winds that leave the Sun radially.

First discovered in the 1970s, according to the India Today report, coronal holes are low-density regions with open magnetic field structures that extend into interplanetary space. These phenomena are intense sources of fast solar wind, streams of charged particles escaping the sun at high speeds. This high-speed solar wind can interact with Earth’s magnetic field, causing geomagnetic storms and disturbances in the Earth’s ionosphere, which can disrupt radio wave communication. The study used full-disk calibrated images from the Solar and Heliospheric Observatory space probe. Researchers from the IIA unambiguously detected these holes and accurately estimated the physical parameters of their thermal and magnetic field structures. They highlighted two key findings as reported by India Today. First, there is no significant variation in the temperature structure of coronal holes across different latitudes. Second, the strength of the magnetic field structure within coronal holes varies with latitude, increasing from the solar equator to the poles. These results suggest that coronal holes likely originate from the deep solar interior and may form from the superposition of Alfven wave perturbations, respectively. IIA researchers have also created a new method to measure solar storms’ size and speed, helping better predict their effects on earth. This technique could improve the ability to forecast disruptions to Earth’s communication systems and power grids.