Phase lags of solar hemispheric cycles

Muraközy, J.; Ludmány, A.

doi:10.1111/j.1365-2966.2011.20011.x

Cited by 32 publications

(14 citation statements)

References 42 publications

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“…Sunspots and other forms of solar magnetic activity are not uniformly distributed in solar longitude, but are centered around certain longitude bands, which are called active longitudes (ALs). Active longitudes have been observed in several studies using different data bases (Temmer et al 2006;Chen et al 2011;Li 2011;Muraközy & Ludmány 2012).…”

Section: Introductionmentioning

confidence: 99%

Solar surface rotation: N-S asymmetry and recent speed-up

Zhang

Мурсула

Usoskin

2015

A&A

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Context. The relation between solar surface rotation and sunspot activity is still not fully resolved. The sunspot activity has been significantly reduced in solar cycle 24, and several solar activity indices and flux measurements experienced unprecedentedly low levels during the last solar minimum. Aims. We aim to reveal the momentary variation of solar surface rotation, especially during the recent years of reduced solar activity. Methods. We used a dynamic, differentially rotating reference system to determine the best-fit annual values of the differential rotation parameters of active longitudes of solar X-ray flares and sunspots in 1977-2012.Results. The evolution of the rotation of solar active longitudes obtained from observing X-ray flares and sunspots is very similar. Both hemispheres have increased their rotation rate since the late 1990s, with the southern hemisphere rotating slightly faster than the north. In the 1980s, rotation in the northern hemisphere was considerably faster, but it experienced a major decrease in the early 1990s. On the other hand, little change was found in the rotation of the southern hemisphere during these decades. This led to a positive asymmetry in the north-south rotation rate in the early part of the time interval studied. Conclusions. The rotation of both hemispheres has been speeding up at roughly the same rate since the late 1990s, with the southern hemisphere rotating slightly faster than the northern hemisphere. This period coincides with the start of a significant weakening of the solar activity, as observed in sunspots and several other solar, interplanetary, and geomagnetic parameters.

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Section: Introductionmentioning

confidence: 99%

Solar surface rotation: N-S asymmetry and recent speed-up

Zhang

Мурсула

Usoskin

2015

A&A

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“…It also shows that there can be a dominant hemisphere for the duration of a full cycle and that sequences of several cycles can exhibit the same hemispheric bias. It should be mentioned here that although a relationship between hemispheric asymmetry and cycle maximum SSN has not been established, it has been suggested that there is a longer‐term periodicity in the preferred hemisphere, possibly associated with the proposed grand cycle (e.g., Murakozy & Ludmany, ; Schussler & Cameron, ). (If their pattern persists, Cycle 25 will have dominant northward activity.)…”

Section: A Dynamo Master Clock?mentioning

confidence: 91%

The Solar Clock

Russell

Jian

Luhmann

2019

Reviews of Geophysics

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The Sun is powered by a very stable source of fusion energy in its core that radiates that energy outward in a constant flow. Yet it has a cycle of magnetic dynamo activity whose strength and duration are variable. This variability, which affects the Earth's “space climate,” points to temporal changes in the convective and diffusive transport of magnetic flux above the tachocline, where the flux is generated. The longest record we have of this variability is the time series of sunspot numbers. This record suggests that the interior of the Sun follows a clock‐like magnetic flux production cycle with a length of close to 11.05 years. The variations in sunspot cycle duration, as well as the sunspot number rise and fall times, their hemispheric asymmetries, and the maximum sunspot numbers of the individual cycles are likely produced in the process of the magnetic flux transport. Helioseismology continues to shed more light on the convection zone variabilities, including the “torsional oscillations” that seem to have a special connection to the emerging strong magnetic fluxes that produce the sunspots. These new observations may eventually lead to an explanation for the surprisingly good correlation between the rate of sunspot appearance and the maximum sunspot number and to a better understanding of the relationship between the solar dynamo and the sunspot number cycle. Better understanding of the polar regions awaits long‐term monitoring with a polar solar mission. Better predictions of near‐term space weather could be obtained from a permanent L5 monitor.

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“…There are more sunspots in NH for 1950-1970 and excess sunspots in SH for descent of cycles 21-23 (1980-2010) more so for the Cycle 24 decay phase (Svalgaard and Kamide, 2013; Ahluwalia, 2015bAhluwalia, , 2016. Murakozy and Ludm´any (2012) analyzed hemispheric SSN data from the Greenwich Royal Observatory for 12 cycles (12-23), finding phase of hemispheric cycles shows an alternating variation; NH leads in 4 and follows in 4 cycles, 4+4 cycle period is close to Gleissberg (1939) cycle; Zolotova et al (2009) reached a similar conclusion. Vernova et al (2014) find that the Cycle 24 may be violating this rule.…”

Section: Ssn(v2)mentioning

confidence: 99%

Holistic study of space weather and space climate: 1700- 2018

Ahluwalia¹

2019

Proceedings of 36th International Cosmic Ray Conference — PoS(ICRC2019)

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We present an update of changes in space weather/space climate at Earth orbit using sunspot number (SSN) timeline (1700-2018), geomagnetic indices aa/Ap (1870-2018), solar polar magnetic field (1976-2017), interplanetary magnetic field (IMF) and galactic cosmic ray (GCR) flux (1963-2018) in the stratosphere at high latitudes. The Cycle 24 is close to minimum, expected in 2020. The baseline of aa index increases monotonically from 1900 to 1986 declining steeply afterwards, solar polar magnetic field decreases systematically for last three cycles (22-24) as do SSNs at cycle peaks. Livingston and Penn (2009) note a long term weakening of maximum magnetic field in sunspots since 1992. They expect SSNs for the Cycle 25 to peak at 7 (a steep decline in solar activity) leading to Maunder-like minimum, in contrast to prediction of a Dalton minimum by several colleagues. The North-South asymmetry in the solar polar field is pronounced for the decay phase of cycles 23, 24, itseems to change sign after the Cycle 21. GCR flux in the stratosphere is higher than in 1965 and increasing, pointing to an enhanced radiation exposure in future for passengers on transpolar flights, the astronauts on the space station as well as those travelling to and staying on the Moon and the Mars on prolonged missions; the assets in space would have to be hardened for safety from enhanced radiation.

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Phase lags of solar hemispheric cycles

Cited by 32 publications

References 42 publications

Solar surface rotation: N-S asymmetry and recent speed-up

Solar surface rotation: N-S asymmetry and recent speed-up

The Solar Clock

Holistic study of space weather and space climate: 1700- 2018

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