Related papers: Tracing sunspot groups to determine angular moment…
Sunspot position data obtained from Kanzelh\"{o}he Observatory for Solar and Environmental Research (KSO) sunspot drawings and white light images in the period 1964 to 2016 were used to calculate the rotational and meridional velocities of…
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…
We analyzed the combined 142 years sunspot-group data from Greenwich Photoheliograpic Results (GPR) and Debrecen Photoheliographic Data (DPD) and determined the yearly mean residual rotation rate and the meridional velocity of sunspot…
The analysis of the meridional displacement velocity of individual solar pores and sunspots has been performed. In the period May 2010\,-\,March 2025 of observations in the continuum of the \textit{Solar Dynamics Observatory/Helioseismic…
Context. It is possible to detect and track coronal bright points (CBPs) in SDO/AIA images. Combination of high resolution and high cadence provides a wealth of data that can be used to determine velocity flows on the solar surface with…
The empirical finding with data from the Solar Dynamics Observatory (SDO) of positive (negative) horizontal Reynolds stress at the northern (southern) hemisphere for solar giant cells (Hathaway et al. 2013) is discussed for its consequences…
Using the Solar Optical Observing Network (SOON) sunspot-group data for the period 1985-2010, the variations in the annual mean equatorial-rotation rates of the sunspot groups are determined and compared with the known variations in the…
We find that the mean meridional motion of the spot groups varies considerably on a time scale of about 5-20 years. The maximum amplitude of the variation is about 10-15 m/s in both the Sun's northern and the southern hemispheres. Variation…
The solar torsional oscillations, i.e., the perturbations of the angular velocity of rotation associated with the eleven-year activity cycle, are a manifestation of the interaction among the interior magnetic fields, amplified and modulated…
The differential rotation plays a crucial role in the dynamics of the Sun. We study the solar rotation and its correlation with solar activity by applying a modified machine learning algorithm to identify and track coronal bright points…
The rotation of sunspots of 2 yr in two different solar cycles is studied with the data from the Helioseismic and Magnetic Imager on board the \it Solar Dynamics Observatory \rm and the Michelson Doppler Imager instrument on board the \it…
We present a series of 3-D nonlinear simulations of solar-like convection, carried out using the Anelastic Spherical Harmonic (ASH) code, that are designed to isolate those processes that drive and shape meridional circulations within…
The sunspot position from Greenwich Photoheliographic Results (GPR), US Air Force Solar Optical Observing Network and National Oceanic and Atmospheric Administration (USAF/NOAA), and Debrecen Photoheliographic Data (DPD) data bases in the…
The long-term evolution of the Sun's rotation period cannot be directly observed, and is instead inferred from trends in the measured rotation periods of other Sun-like stars. Assuming the Sun spins-down as it ages, following rotation rate…
The main object of the paper is to present the condition of the non-diffusive part of the Reynolds stress for driving the double-cell structure of the solar meridional circulation, which has been revealed by recent helioseismic…
We analyse the monthly sunspot group (SG) data for Solar Cycles C8-C23 and calculate the average latitude of the drift path for the northern and southern hemisphere of the Sun. We find that exponential function fits slightly better than the…
The rate at which the solar wind extracts angular momentum from the Sun has been predicted by theoretical models for many decades, and yet we lack a conclusive measurement from in-situ observations. In this letter we present a new estimate…
We have detected several periodicities in the solar equatorial rotation rate of sunspot groups in the Greenwich Photoheliographic Results (GPR) during the period 1931-1976, the Solar Optical Observing Network (SOON) during the period…
We measure the eddy viscosity in the outermost layers of the solar convection zone by comparing the rotation law computed with the Reynolds stress resulting from f-plane simulations of the angular momentum transport in rotating convection…
We obtain lower limits on the amplitude of convective velocities in the deep solar convection zone based only on the observed properties of the differential rotation and meridional circulation together with simple and robust dynamical…