Modeling the cyclic modulation of photospheric lines

Penza, V.; Pietropaolo, E.; Livingston, W.

doi:10.1051/0004-6361:20053405

Cited by 25 publications

(28 citation statements)

References 26 publications

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“…Earlier results obtained with both a regression method and a semi-empirical model were presented by, e.g. Penza et al (2003Penza et al ( , 2006, Domingo et al (2009) and Ermolli et al (2011). A new semi-empirical model, briefly outlined below, is currently under development (Ermolli et al, 2012).…”

Section: Oarmentioning

confidence: 94%

Recent variability of the solar spectral irradiance and its impact on climate modelling

et al. 2013

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The lack of long and reliable time series of solar spectral irradiance (SSI) measurements makes an accurate quantification of solar contributions to recent climate change difficult. Whereas earlier SSI observations and models provided a qualitatively consistent picture of the SSI variability, recent measurements by the SORCE (SOlar Radiation and Climate Experiment) satellite suggest a significantly stronger variability in the ultraviolet (UV) spectral range and changes in the visible and near-infrared (NIR) bands in anti-phase with the solar cycle. A number of recent chemistry-climate model (CCM) simulations have shown that this might have significant implications on the Earth's atmosphere. Motivated by these results, we summarize here our current knowledge of SSI variability and its impact on Earth's climate.

We present a detailed overview of existing SSI measurements and provide thorough comparison of models available to date. SSI changes influence the Earth's atmosphere, both directly, through changes in shortwave (SW) heating and therefore, temperature and ozone distributions in the stratosphere, and indirectly, through dynamical feedbacks. We investigate these direct and indirect effects using several state-of-the art CCM simulations forced with measured and modelled SSI changes. A unique asset of this study is the use of a common comprehensive approach for an issue that is usually addressed separately by different communities.

We show that the SORCE measurements are difficult to reconcile with earlier observations and with SSI models. Of the five SSI models discussed here, specifically NRLSSI (Naval Research Laboratory Solar Spectral Irradiance), SATIRE-S (Spectral And Total Irradiance REconstructions for the Satellite era), COSI (COde for Solar Irradiance), SRPM (Solar Radiation Physical Modelling), and OAR (Osservatorio Astronomico di Roma), only one shows a behaviour of the UV and visible irradiance qualitatively resembling that of the recent SORCE measurements. However, the integral of the SSI computed with this model over the entire spectral range does not reproduce the measured cyclical changes of the total solar irradiance, which is an essential requisite for realistic evaluations of solar effects on the Earth's climate in CCMs.

We show that within the range provided by the recent SSI observations and semi-empirical models discussed here, the NRLSSI model and SORCE observations represent the lower and upper limits in the magnitude of the SSI solar cycle variation.

The results of the CCM simulations, forced with the SSI solar cycle variations estimated from the NRLSSI model and from SORCE measurements, show that the direct solar response in the stratosphere is larger for the SORCE than for the NRLSSI data. Correspondingly, larger UV forcing also leads to a larger surface response.

Finally, we discuss the reliability of the available data and we propose additional coordinated work, first to build composite SSI data sets out of scattered observations and to r...

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Section: Oarmentioning

confidence: 94%

Recent variability of the solar spectral irradiance and its impact on climate modelling

et al. 2013

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“…The quasi-biennial component of the solar cycle, although weaker than the main one, is very robust since it has been recorded by many indicators (see e.g. Kane 2005;Penza et al 2006;Li et al 2006;Cadavid et al 2005). The peak in P j (T ) corresponding to the short-term contribution, although significant, is underestimated compared to the main cycle peak.…”

Section: Time Evolution Of Pod Coefficients: Wavelet Analysis and Permentioning

confidence: 99%

“…Gnevyshev 1977;Rusin & Zverko 1990;Bay 2003;Kane 2005;Vecchio et al 2005;Penza et al 2006). Among the yearly periodicities, the most noticeable periods are 1.3 years and 3.6 years, along with some periods in the range between 2.6 years and 2.8 years (for a complete classification of the high-frequency periodicities observed in many solar indices see e.g.…”

Section: Introductionmentioning

confidence: 99%

Spatio-temporal analysis of solar activity: main periodicities and period length variations

Vecchio

Carbone

2009

A&A

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Aims. The spatio-temporal dynamics of solar activity has been investigated by studying the main oscillations and the time evolution of the basic periods. Methods. The spatio-temporal behavior of the green coronal emission line at 530.3 nm, recorded from 1939 to 2005, has been analyzed by using proper orthogonal decomposition, to extract the main components of the system, and the wavelet analysis to further investigate their time behaviour.Results. In addition to the main 11-year periodicity, a high-frequency component has been recorded mainly on the polar regions of the Sun, thus indicating a different origin from the emergence of active regions. Evidence for variations in the period lengths of this component has been found for the first time. The calculated period length varies between 1.5 years and 4 years, in good agreement with frequencies attributed to the quasi-biennial cycle extracted by different solar activity indicators. Our analysis shows that, unlike the main periodicity, the high-frequency component does not show the typical properties of a true mode of oscillation but seems to originate, in a narrow band of frequencies, from a stochastic superposition of different oscillators. Conclusions. The observed solar cycle frequencies in the range 1.5−4 years, commonly considered as independent modes of oscillation, could be the manifestation of the temporal modulation of a unique quasi-biennial periodicity. Our findings can provide more constraints on dynamo models introduced to describe the different components of the solar cycle. The calculated period length variations could also be helpful to improve our knowledge of the relationship between solar activity, neutrino flux variations and cosmic ray modulation.

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“…Interestingly, Livingston et al (2007) could not confirm this finding in the next solar cycle for the unblended strong Fe I and the Na I D lines. This is, probably, a good indication of how challenging such observations are (see also discussion in Penza et al 2006). Instead, Livingston et al (2007) reported cyclic variation in the Mn I 539.4 nm line and the CN 388.3 nm bandhead.…”

Section: Introductionmentioning

confidence: 97%

The role of the Fraunhofer lines in solar brightness variability

Шапиро

Solanki

Krivova

et al. 2015

A&A

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Context. The solar brightness varies on timescales from minutes to decades. A clear identification of the physical processes behind such variations is needed for developing and improving physics-based models of solar brightness variability and reconstructing solar brightness in the past. This is, in turn, important for better understanding the solar-terrestrial and solar-stellar connections. Aims. We estimate the relative contributions of the continuum, molecular, and atomic lines to the solar brightness variations on different timescales. Methods. Our approach is based on the assumption that variability of the solar brightness on timescales greater than a day is driven by the evolution of the solar surface magnetic field. We calculated the solar brightness variations employing the solar disc area coverage of magnetic features deduced from the MDI/SOHO observations. The brightness contrasts of magnetic features relative to the quiet Sun were calculated with a non-LTE radiative transfer code as functions of disc position and wavelength. By consecutive elimination of molecular and atomic lines from the radiative transfer calculations, we assessed the role of these lines in producing solar brightness variability. Results. We show that the variations in Fraunhofer lines define the amplitude of the solar brightness variability on timescales greater than a day and even the phase of the total solar irradiance variability over the 11-year cycle. We also demonstrate that molecular lines make substantial contribution to solar brightness variability on the 11-year activity cycle and centennial timescales. In particular, our model indicates that roughly a quarter of the total solar irradiance variability over the 11-year cycle originates in molecular lines. The maximum of the absolute spectral brightness variability on timescales greater than a day is associated with the CN violet system between 380 and 390 nm.

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Modeling the cyclic modulation of photospheric lines

Cited by 25 publications

References 26 publications

Recent variability of the solar spectral irradiance and its impact on climate modelling

Recent variability of the solar spectral irradiance and its impact on climate modelling

Spatio-temporal analysis of solar activity: main periodicities and period length variations

The role of the Fraunhofer lines in solar brightness variability

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