The Relationship Between Plasma Flow Doppler Velocities and Magnetic Field Parameters During the Emergence of Active Regions at the Solar Photospheric Level

TL;DR

This study analyzes the relationship between plasma flow velocities and magnetic field parameters during active region emergence on the Sun, revealing how these dynamics vary with position and magnetic flux growth.

Contribution

It provides a comprehensive statistical analysis of plasma flows and magnetic parameters during active region emergence, using data from SOHO/MDI, which is novel in scope and detail.

Findings

Peak Doppler velocities vary with position on the solar disc.

Magnetic flux growth rate correlates with plasma flow velocities.

Doppler velocities relate to magnetic flux during early active region development.

Abstract

A statistical study has been carried out of the relationship between plasma flow Doppler velocities and magnetic field parameters during the emergence of active regions at the solar photospheric level with data acquired by the Michelson Doppler Imager (MDI) onboard the Solar and Heliospheric Observatory (SOHO). We have investigated 224 emerging active regions with different spatial scales and positions on the solar disc. The following relationships for the first hours of the emergence of active regions have been analysed: i) of peak negative Doppler velocities with the position of the emerging active regions on the solar disc; ii) of peak plasma upflow and downflow Doppler velocities with the magnetic flux growth rate and magnetic field strength for the active regions emerging near the solar disc centre (the vertical component of plasma flows); iii) of peak positive and negative Doppler velocities with the magnetic flux growth rate and magnetic field strength for the active regions emerging near the limb (the horizontal component of plasma flows); iv) of the magnetic flux growth rate with the density of emerging magnetic flux; v) of the Doppler velocities and magnetic field parameters for the first hours of the appearance of active regions with the total unsigned magnetic flux at the maximum of their development.