The detection of Rossby-like waves on the Sun

McIntosh, Scott W.; Cramer, W. J.; Marcano, Manuel Pichardo; Leamon, Robert J.

doi:10.1038/s41550-017-0086

Cited by 93 publications

(74 citation statements)

References 33 publications

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“…n = 4 harmonics for the same field strength gives the period of 170 days for fast magneto-Rossby waves and 1.3 years for slow magneto-Rossby waves. Here we see that with the equipartition field strength, the m = 1, n = 4 harmonic of fast magneto-Rossby waves gives the value of Rieger-type periodicity, while the same harmonic of slow magneto-Rossby waves gives the similar value of annual oscillation (McIntosh et al, 2017). It is remarkable that the period exactly equals to the periodicity obtained by helioseismology near the base of convection zone (Howe et al, 2000).…”

Section: Spherical Rossby Wavessupporting

confidence: 62%

“…Therefore, this mode was called as n = −1 mode by Matsuno (1966). The time scale of Kelvin waves is few years (see Figure 6), therefore it is in the range of quasi biennial (Sakurai, 1979;Zaqarashvili et al, 2010b) and/or annual oscillations (McIntosh et al, 2015(McIntosh et al, , 2017.…”

Section: Kelvin Wavesmentioning

confidence: 99%

“…Rossby waves govern large scale dynamics of rotating sphere and are well studied in the Earth's atmosphere and oceans (Rossby, 1939;Gill, 1982). Recent direct observations of Rossby waves in coronal bright points based on STEREO and SDO observations (McIntosh et al, 2017) significantly increased the interest toward Rossby waves in the solar context. Lou (2000) suggested that the equatorially trapped hydrodynamic Rossby waves in the solar photosphere could explain Riegertype periodicity in solar activity.…”

Section: Introductionmentioning

confidence: 99%

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Magneto-Rossby Waves and Seismology of Solar Interior

Zaqarashvili

Gurgenashvili

2018

Front. Astron. Space Sci.

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Eleven-year Schwabe cycle in solar activity is not yet fully understood despite of its almost two century discovery. It is generally interpreted as owing to some sort of magnetic dynamo operating below or inside the convection zone. The magnetic field strength in the dynamo layer may determine the importance of the tachocline in the model which is responsible for the cyclic magnetic field, but the direct measurement is not possible. On the other hand, solar activity also displays short term variations over time scale of months (Rieger-type periodicity), which significantly depend on solar activity level: stronger cycles (or more active hemisphere in each cycle) generally show shorter periodicity and vice versa. The periodicity is probably connected to Rossby-type waves in the dynamo layer, therefore alongside with wave dispersion relations it might be used to estimate the dynamo magnetic field strength. We performed the wavelet analysis of hemispheric sunspot areas during solar cycles 13-24 and corresponding hemispheric values of Rieger-type periodicity are found in each cycle. Two different Rossby-type waves could lead to observed periodicities: spherical fast magneto-Rossby waves and equatorial Poincare-Rossby waves. The dispersion relation of spherical fast magneto-Rossby waves gives the estimated field strength of >40 kG in stronger cycles (or in more active hemisphere) and <40 kG in weaker cycles (or in less active hemisphere). The equatorial Poincare-Rossby waves lead to >20 kG and <15 kG, respectively. Future perspectives of Rieger-type periodicities and Rossby-type waves in testing various dynamo models are discussed.

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Section: Spherical Rossby Wavessupporting

confidence: 62%

Section: Kelvin Wavesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Magneto-Rossby Waves and Seismology of Solar Interior

Zaqarashvili

Gurgenashvili

2018

Front. Astron. Space Sci.

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“…Screen & Simmonds 2014). The Sun rotates slowly but the Rossby waves still can be observed by tracking the coronal brightpoints and the south-north helioseismic travel times (McIntosh et al 2017;Löptien et al 2018;Liang et al 2018). They have the potential to improve our understanding of energy transfer, solar activity, and space weather (Zaqarashvili et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Period spacings of γ Doradus pulsators in the Kepler field: Rossby and gravity modes in 82 stars

Reeth

Bedding

et al. 2019

Monthly Notices of the Royal Astronomical Society

110

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Rossby modes are the oscillations in a rotating fluid, whose restoring force is the Coriolis force. They provide an additional diagnostic to understand the rotation of stars, which complicates asteroseismic modelling. We report 82 γ Doradus stars for which clear period spacing patterns of both gravity and Rossby modes have been detected. The period spacings of both show a quasi-linear relation with the pulsation period but the slope is negative for the gravity modes and positive for the Rossby modes. Most Rossby modes have k = −2, m = −1. For only one star a series of k = −1, m = −1 modes is seen. For each pattern, the mean pulsation period, the mean period spacing, and the slope are measured. We find that the slope correlates with the mean period for Rossby mode patterns. The traditional approximation of rotation is used to measure the near-core rotation rate, assuming the star rotates rigidly. We report the near-core rotation rates, the asymptotic period spacings, and the radial orders of excited modes of these 82 main-sequence stars. The near-core rotation rates lie between 0.6 d −1 and 2.3 d −1 . Six stars show surface rotation modulations, among which only KIC 3341457 shows differential rotation while the other five stars have uniform rotations. The radial orders of excited modes show different distributions for the dipole and quadrupole gravity modes versus the Rossby modes.

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“…Recently, McIntosh et al (2017) have found clear evidence of the longitudinal propagation of wavelike features seen in coronal bright points and have identified these as Rossby waves. Krista et al (2018) have found similar evidence of propagating Rossby waves in the longitudinal evolution of coronal holes.…”

Section: Introductionmentioning

confidence: 99%

Phase Speed of Magnetized Rossby Waves that Cause Solar Seasons

Dikpati

Belucz

Gilman

et al. 2018

ApJ

Self Cite

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Motivated by recent analysis of solar observations that show evidence of propagating Rossby waves in coronal holes and bright points, we compute the longitudinal phase velocities of unstable MHD Rossby waves found in an MHD shallow-water model of the solar tachocline (both overshoot and radiative parts). We demonstrate that phase propagation is a typical characteristic of tachocline nonlinear oscillations that are created by unstable MHD Rossby waves, responsible for producing solar seasons. For toroidal field bands placed at latitudes between 5°and 75°, we find that phase velocities occur in a range similar to the observations, with more retrograde speeds (relative to the solar core rotation rate) for bands placed at higher latitudes, just as coronal holes have at high latitudes compared to low ones. The phase speeds of these waves are relatively insensitive to the toroidal field peak amplitude. Rossby waves for single bands at 25°are slightly prograde. However, at latitudes lower than 25°they are very retrograde, but much less so if a second band is included at a much higher latitude. This double-band configuration is suggested by evidence of an extended solar cycle, containing a high-latitude band in its early stages that does not yet produce spots, while the spot-producing low-latitude band is active. Collectively, our results indicate a strong connection between longitudinally propagating MHD Rossby waves in the tachocline and surface manifestations in the form of similarly propagating coronal holes and patterns of bright points.

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The detection of Rossby-like waves on the Sun

Cited by 93 publications

References 33 publications

Magneto-Rossby Waves and Seismology of Solar Interior

Magneto-Rossby Waves and Seismology of Solar Interior

Period spacings of γ Doradus pulsators in the Kepler field: Rossby and gravity modes in 82 stars

Phase Speed of Magnetized Rossby Waves that Cause Solar Seasons

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