The solar meridional circulation and sunspot cycle variability

Hathaway, David H.; Upton, Lisa

doi:10.1002/2013ja019432

Cited by 52 publications

(32 citation statements)

References 61 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, the surface meridional flow is observed to change with the solar cycle and most of this variation is probably caused by the inflows around the active regions (Gizon et al 2010). This meridional flow perturbation can change the polar field from cycle to cycle (Jiang et al 2010;Hathaway & Upton 2014;Shetye et al 2015). In our study, we have not considered how the polar field could be varied in cycle to cycle.…”

Section: Conclusion and Discussionmentioning

confidence: 97%

Latitude Distribution of Sunspots: Analysis Using Sunspot Data and a Dynamo Model

Mandal

Karak

Banerjee

2017

ApJ

View full text Add to dashboard Cite

In this paper, we explore the evolution of sunspot latitude distribution and explore its relations with the cycle strength. With the progress of the solar cycle the distributions in two hemispheres from mid-latitudes propagate toward the equator and then (before the usual solar minimum) these two distributions touch each other. By visualizing the evolution of the distributions in two hemispheres, we separate the solar cycles by excluding this hemispheric overlap. From these isolated solar cycles in two hemispheres, we generate latitude distributions for each cycle, starting from cycle 8 to cycle 23. We find that the parameters of these distributions, namely, the central latitude (C), width (δ) and height (H) evolve with the cycle number and they show some hemispheric asymmetries. Although the asymmetries in these parameters persist for a few successive cycles, they get corrected within a few cycles and the new asymmetries appear again. In agreement with the previous study, we find that distribution parameters are correlated with the strengths of the cycles, although these correlations are significantly different in two hemispheres. The general trend that stronger cycles begin sunspot eruptions at relatively higher latitudes and have wider bands of sunspot emergence latitudes are confirmed when combining the data from two hemispheres. We explore these features using a flux transport dynamo model with stochastic fluctuations. We find that these features are correctly reproduced in this model. The solar cycle evolution of the distribution center is also in good agreement with observations. Possible explanations of the observed features based on this dynamo model are presented.

show abstract

Section: Conclusion and Discussionmentioning

confidence: 97%

Latitude Distribution of Sunspots: Analysis Using Sunspot Data and a Dynamo Model

Mandal

Karak

Banerjee

2017

ApJ

View full text Add to dashboard Cite

show abstract

“…Our meridional flow is slightly slower than the meridional flow discussed by Komm et al (1993) for the time interval from 1975 to 1991. Hathaway & Upton (2014) also discussed the meridional circulation in solar cycle 24 using HMI data from the time interval of April 2010 to July 2013. Their results also seem to be consistent with our results at not only low latitudes but also high latitudes.…”

Section: Discussion and Summarymentioning

confidence: 99%

“…The meridional flow has also been discussed for a long time, and the poleward flow at low and intermediate latitudes is well established (e.g., Hathaway & Upton 2014). Because this flow is two to three orders of magnitude slower than the rotational flow, its basic entire structure is difficult to observe and is still controversial.…”

Section: Introductionmentioning

confidence: 99%

Effect of Magnetic Field Strength on Solar Differential Rotation and Meridional Circulation

Imada

Fujiyama

2018

ApJL

View full text Add to dashboard Cite

We studied the solar surface flows (differential rotation and meridional circulation) using a magnetic element feature tracking technique by which the surface velocity is obtained using magnetic field data. We used the line-of-sight magnetograms obtained by the Helioseismic and Magnetic Imager aboard the Solar Dynamics Observatory from 01 May 2010 to 16 August 2017 (Carrington rotations 2096 to 2193) and tracked the magnetic element features every hour. Using our method, we estimated the differential rotation velocity profile. We found rotation velocities of ∼ 30 and -170 m s −1 at latitudes of 0 • and 60 • in the Carrington rotation frame, respectively. Our results are consistent with previous results obtained by other methods, such as direct Doppler, time-distance helioseismology, or cross correlation analyses. We also estimated the meridional circulation velocity profile and found that it peaked at ∼12 m s −1 at a latitude of 45 • , which is also consistent with previous results. The dependence of the surface flow velocity on the magnetic field strength was also studied. In our analysis, the magnetic elements having stronger and weaker magnetic fields largely represent the characteristics of the active region remnants and solar magnetic networks, respectively. We found that magnetic elements having a strong (weak) magnetic field show faster (slower) rotation speed. On the other hand, magnetic elements having a strong (weak) magnetic field show slower (faster) meridional circulation velocity. These results might be related to the Sun's internal dynamics.

show abstract

“…This analysis on an independent data set using different measurement techniques strengthens the conclusions of Zhao et al (2013) and Schad et al (2013a) that the convection zone may have multiple cells of meridional flow. Variations of the meridional flow speed, associated with large-scale converging flows around active regions, are considered as a key mechanism regulating the strength of the solar cycles (Hathaway & Upton 2014). These variations were studied by Komm et al (2015b,a); Zhao et al (2014).…”

Section: Research Highlights: the Solar Compositionmentioning

confidence: 99%