Dynamics of the solar chromosphere 
 IV. Evidence for atmospheric gravity waves from TRACE

Rutten, R. J.; Krijger, J. M.

doi:10.1051/0004-6361:20030894

Cited by 46 publications

(48 citation statements)

References 19 publications

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“…Studies of the H I Lyman continuum (Wilhelm and Kalkofen 2003) and the C II 133.5 nm multiplet (Judge et al 2003) both indicated a heating of the upper chromosphere by magnetic effects and not by acoustic waves. However, Gallagher et al (1999) found indications of heating by acoustic shocks even in the transition region near 2.5 × 10 5 K. Evidence for atmospheric gravity waves was found from TRACE observations (Rutten and Krijger 2003).…”

Section: Chromospheric Oscillationsmentioning

confidence: 97%

Observations of the Sun at Vacuum-Ultraviolet Wavelengths from Space. Part II: Results and Interpretations

et al. 2007

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In Part I of this review, the concepts of solar vacuum-ultraviolet (VUV) observations were outlined together with a discussion of the space instrumentation used for the investigations. A section on spectroradiometry provided some quantitative results on the solar VUV radiation without considering any details of the solar phenomena leading to the radiation. Here, in Part II, we present solar VUV observations over the last decades and their interpretations in terms of the plasma processes and the parameters of the solar atmosphere, with emphasis on the spatial and thermal structures of the chromosphere, transition region and corona of the quiet Sun. In addition, observations of active regions, solar flares and prominences are included as well as of small-scale events. Special sections are devoted to the elemental composition of the solar atmosphere and theoretical considerations on the heating of the corona and the generation of the solar wind.

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Section: Chromospheric Oscillationsmentioning

confidence: 97%

Observations of the Sun at Vacuum-Ultraviolet Wavelengths from Space. Part II: Results and Interpretations

et al. 2007

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“…In the evanescent regime (7 min oscillations), most of the internetwork exhibits small absolute phase differences (between ±20 degrees), as is expected for standing or evanescent waves. Larger negative phase differences have been attributed to downward propagating gravity waves (Cauzzi et al 2000;Krijger et al 2001;Rutten & Krijger 2003).…”

Section: Phase Differences and Coherencementioning

confidence: 99%

Power halo and magnetic shadow in a solar quiet region observed in the Hαline

Kontogiannis

Tsiropoula

Tziotziou

2010

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Context. We investigate the oscillatory behavior of the quiet solar chromosphere and its discrete components in terms of oscillation properties, i.e. network and internetwork. For this purpose, we use a time series of high resolution filtergrams at five wavelengths along the Hα profile, obtained by the Dutch Open Telescope. Aims. We aim to gain insight on the distribution of power in different period bands and its variation between network and internetwork. Our spectral resolution provides information on the vertical distribution of power, since the Hα line has both photospheric and chromospheric components. We investigate the effect of Hα mottles on chromospheric oscillations, since they are the most prominent feature of the Hα chromosphere and outline inclined magnetic fields. Methods. We use wavelet and phase difference analyses of Hα intensities and Doppler signals. Two-dimensional power maps in the 3, 5 and 7 min period bands as well as coherence and phase difference maps were constructed. Results. At photospheric heights, where the Hα ± 0.7 Å wing is formed, the 3 and 5 min power is enhanced around the network, and forms power halos. Higher in the chromosphere these areas are replaced by magnetic shadows, i.e. places of power suppression. Interestingly, the power maps show a filamentary structure in the network which correlates very well with mottles. These areas show positive phase differences at the 3 min period band. At the 5 min and 7 min period bands both positive and negative phase differences are obtained with an increased number of pixels with high coherence, indicating the existence of both upward and downward propagating waves. Conclusions. We attribute our findings to the interaction between acoustic oscillations and the magnetic fields that constitute the magnetic network. The network flux tubes diverge at chromospheric levels and obtain a significant horizontal component, which is betrayed by the presence of mottles. The variation of power reveals the discrete role of the magnetic field at different heights, which guides or suppresses the oscillations, depending on its inclination. Spectral resolution in Hα provides useful information on the coupling between the acoustic sub-canopy atmosphere and the magnetized chromosphere.

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“…According to the VAL-C solar atmosphere model (Vernazza et al 1981), the temperature minimum region is located at about 500 km above τ 500 = 1, corresponding to the upper photosphere/lower chromosphere (Worden et al 1999;Rutten & Krijger 2003;McAteer et al 2004).…”

Section: Formation Height Of Emission From Trace Uv Filtersmentioning

confidence: 99%

Horizontal supergranule-scale motions inferred from TRACE ultraviolet observations of the chromosphere

Potts

Marsch

Attié

et al. 2010

A&A

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Aims. We study horizontal supergranule-scale motions revealed by TRACE observation of the chromospheric emission, and investigate the coupling between the chromosphere and the underlying photosphere. Methods. A highly efficient feature-tracking technique called balltracking has been applied for the first time to the image sequences obtained by TRACE (transition region and coronal explorer) in the passband of white light and the three ultraviolet passbands centered at 1700 Å, 1600 Å, and 1550 Å. The resulting velocity fields have been spatially smoothed and temporally averaged in order to reveal horizontal supergranule-scale motions that may exist at the emission heights of these passbands. Results. We find indeed a high correlation between the horizontal velocities derived in the white-light and ultraviolet passbands. The horizontal velocities derived from the chromospheric and photospheric emission are comparable in magnitude. Conclusions. The horizontal motions derived in the UV passbands might indicate the existence of a supergranule-scale magnetoconvection in the chromosphere, which may shed new light on the study of mass and energy supply to the corona and solar wind at the height of the chromosphere. However, it is also possible that the apparent motions reflect the chromospheric brightness evolution as produced by acoustic shocks which might be modulated by the photospheric granular motions in their excitation process, or advected partly by the supergranule-scale flow towards the network while propagating upward from the photosphere. To reach a firm conclusion, it is necessary to investigate the role of granular motions in the excitation of shocks through numerical modeling, and future high-cadence chromospheric magnetograms must be scrutinized.

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Dynamics of the solar chromosphere IV. Evidence for atmospheric gravity waves from TRACE

Cited by 46 publications

References 19 publications

Observations of the Sun at Vacuum-Ultraviolet Wavelengths from Space. Part II: Results and Interpretations

Observations of the Sun at Vacuum-Ultraviolet Wavelengths from Space. Part II: Results and Interpretations

Power halo and magnetic shadow in a solar quiet region observed in the Hαline

Horizontal supergranule-scale motions inferred from TRACE ultraviolet observations of the chromosphere

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