Meridional Motion and Reynolds Stress from Debrecen Photoheliographic Data

Abstract

The Debrecen Photoheliographic Data catalogue is a continuation of the Greenwich Photoheliographic Results providing daily positions of sunspots and sunspot groups. We analyse the data for sunspot groups focusing on meridional motions and transfer of angular momentum towards the solar equator. Velocities are calculated with a daily shift method including an automatic iterative process of removing the outliers. Apart from the standard differential rotation profile, we find meridional motion directed towards the zone of solar activity. The difference in measured meridional flow in comparison to Doppler measurements and some other tracer measurements is interpreted as a consequence of different flow patterns inside and outside of active regions. We also find a statistically significant dependence of meridional motion on rotation velocity residuals confirming the transfer of angular momentum towards the equator. Analysis of horizontal Reynolds stress reveals that the transfer of angular momentum is stronger with increasing latitude up to about 40${}^{\circ }$ where there is a possible maximum in absolute value.

arXiv comment16 pages, 5 figures

References in corpus (12)

• Deeply penetrating banded zonal flows in the solar convection zone
• Changes in Solar Dynamics from 1995 to 2002
• On-line Tools for Solar Data Compiled at the Debrecen Observatory and their Extensions with the Greenwich Sunspot Data
• Comparative analysis of Debrecen sunspot catalogues
• Subsurface Meridional Circulation in the Active Belts
• Meridional Circulation During the Extended Solar Minimum: Another Component of the Torsional Oscillation?
• Validity of the relations between the synodic and sidereal rotation velocities of the Sun
• Steps toward a high precision solar rotation profile: Results from SDO/AIA coronal bright point data
• Tracing sunspot groups to determine angular momentum transfer on the Sun
• Meridional motions and Reynolds stress from SDO/AIA coronal bright points data
• Reconstruction of Solar Subsurfaces by Local Helioseismology
• Long-term variations in the mean meridional motion of the sunspot groups

Cited by in corpus (9)

• A Relationship between the Solar Rotation and Activity Analysed by Tracing Sunspot Groups
• Solar differential rotation in the period 1964 - 2016 determined by the Kanzelhöhe data set
• Differential rotation of the solar corona: A new data-adaptive multiwavelength approach
• Large-scale photospheric motions determined from granule tracking and helioseismology from SDO/HMI data
• On the origin of the double cell meridional circulation in the solar convection zone
• Meridional Motions and Reynolds Stress Determined by Using Kanzelhöhe Drawings and White Light Solar Images from 1964 to 2016
• Comparison Between Cycle-to-Cycle Variations in the Coefficient of Joy's Law and Covariance of Rotation Residuals and Meridional Motions of Sunspot Groups
• A Study of Variations in Correlation Between Rotation Residual and Meridional Velocity of Sunspot Groups
• Centre to limb brightness variations from ALMA full disk solar images