(GIST OF SCIENCE REPORTER) Sun’s Subsurface Weather

(JUNE-2025)

Sun’s Subsurface Weather

Context:

An international team of solar physicists have traced giant tides of plasma beneath the Sun’s surface at a region called the near-surface shear layer (NSSL). 

Key highlights:

• The plasma currents shift with the Sun’s magnetic heartbeat and could have a far-reaching influence on space weather and Earth.

• The Near-Surface Shear Layer (NSSL), extending to about 35,000 km in depth, is a critical region beneath the Sun’s surface. 

• It is marked by distinct rotational behaviours that vary with depth and by changes, over space and time that relate to active region magnetic fields and the solar cycle.

About the Study

Discovery of Plasma Currents

• The study reveals that plasma currents in the NSSL shift in sync with the Sun’s 11-year sunspot cycle.

• These currents are dynamic and pulse in step with the solar cycle, indicating a strong connection between the Sun’s internal flows and its magnetic heartbeat.

Methodology

• Researchers employed helioseismology, a technique that tracks sound waves travelling through the Sun, to observe changes in solar material movement.

• The analysis utilised over a decade of data from NASA’s Solar Dynamics Observatory/Helioseismic and Magnetic Imager (SDO/HMI) and the ground-based Global Oscillations Network Group (GONG) of the National Solar Observatory (NSO), USA.

Flow Patterns and Circulation Cells

• Surface plasma flows were observed to converge toward active sunspot latitudes.

• Midway through the NSSL, these flows reverse direction and move outward, forming circulation cells.

• The Coriolis force, which also influences weather patterns on Earth, plays a significant role in shaping these flows, causing swirling motions and modifying the Sun’s rotational shear

Implications for Solar Dynamics

• The local plasma currents within the NSSL do not drive the Sun’s larger-scale zonal flows (torsional oscillations), suggesting that deeper, yet unidentified processes power these global flows.

• The findings provide new insights into how the Sun’s interior connects to its outer magnetic behaviour and may help improve models for predicting solar activity and space weather

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Courtesy: Science Reporter