Improved solar Lyman α irradiance modeling from 1947 through 1999 based on UARS observations

Woods, Thomas N.; Tobiska, W. Kent; Rottman, G. J.; Worden, J.

doi:10.1029/2000ja000051

Cited by 335 publications

(328 citation statements)

References 59 publications

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“…(8) of Parenti et al (2000) to determine the electron density at heliocentric distances lower than 2.25 R . As for the Lyα line, we adopted the average chomospheric profile reported by Gouttebroze et al (1978), which agrees, within the uncertainties, with the full-disc Lyα intensities measured by the spectrometer SOLSTICE (SOLar STellar Irradiance Comparison Experiment) on the UARS satellite (see Woods et al 2000) during the week of our observations. Figure 1 shows a composite view of the extended solar corona and of the chromosphere, obtained on May 17, 2004.…”

Section: Observations and Data Analysismentioning

confidence: 80%

Physical parameters of a mid-latitude streamer during the declining phase of the solar cycle

Spadaro

Susino

Ventura

et al. 2007

A&A

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Context. Investigating the physical properties of solar coronal streamers is important for understanding their role in the global magnetic structure of the extended solar atmosphere, as well as in the generation of the slow solar wind. Aims. We hope to contribute as completely as possible to the ongoing SOHO instruments campaign devoted to the study of the physical characteristics of coronal streamers at various heliocentric distances. Results. Electron densities and temperatures, H i and O vi kinetic temperatures, and outflow velocities were derived from the line intensities and widths, as well as from the O vi line intensity ratio in the 1.6−5 R range of heights, limited to the central region of the streamer. To our knowledge, the H i outflow velocities obtained in this work are the first ones determined inside a streamer structure. They are significantly lower than those of the O vi ions. This, together with the O vi kinetic temperatures that are much higher than the H i ones, suggest that the absorption of Alfvén waves at the ion cyclotron frequency might also occur inside streamers. Methods. We analyzed ultraviolet H iConclusions. In comparison with other streamers described in the literature, the structure examined in this work generally exhibits lower electron density and neutral hydrogen kinetic temperature. Conversely, the O vi kinetic temperature and outflow velocity radial profiles are consistent with the results for the other examined streamers.

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Section: Observations and Data Analysismentioning

confidence: 80%

Physical parameters of a mid-latitude streamer during the declining phase of the solar cycle

Spadaro

Susino

Ventura

et al. 2007

A&A

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“…[46] The Q EUV derived from the GUVI observations of the disk and limb dayglow provide independent validation of the larger solar cycle variations that SEE observes at wavelengths <45 nm and also provide further confirmation that 2C-type proxy models can underestimate solar cycle variations [Woods et al, 2000]. GUVI also employs in-flight sensitivity tracking by periodic observations of known stellar fluxes, with estimated uncertainty of 10%, and its observations compare well with simultaneous dayglow observations by the Special Sensor Ultraviolet Spectral Imager (SSUSI) on the DMSP F-16 satellite.…”

Section: Irradiance Variability Amplitudesmentioning

confidence: 92%

“…This postulated third component is present mainly in coronal emissions at EUV wavelengths less than 40 nm. In the region 40 to 80 nm, where the flux-weighted average temperature of the quiet Sun in 1 nm bins [obtained from Warren et al, 2001] is typical of transition region emissions (0.5 to 5 × 10 5 K), the additional third component that Woods et al [2000] surmised is not evident. To add to the confusion, the larger solar cycle variations that SEE observes in cooler emissions (10 4 to 10 5 K) in the 80-120 nm range support the need for a third model component, although independent validation is unavailable from other observations.…”

Section: Irradiance Variability Amplitudesmentioning

confidence: 99%

Solar extreme ultraviolet irradiance: Present, past, and future

et al. 2011

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[1] New models of solar extreme ultraviolet (EUV) irradiance variability are constructed in 1 nm bins from 0 to 120 nm using multiple regression of the Mg II and F 10.7 solar activity indices with irradiance observations made during the descending phase of cycle 23. The models have been used to reconstruct EUV spectra daily since 1950, annually since 1610, to forecast daily EUV irradiance and to estimate future levels in cycle 24. A two-component model developed by scaling the observed rotational modulation of the two solar indices underestimates the solar cycle changes that the Solar EUV Experiment (SEE) reports at wavelengths shorter than 40 nm and longer than 80 nm. A three-component model implemented by including an additional term derived from the smoothed Mg II index better reproduces the measurements at all wavelengths. The three-component model is consistent with variations in the EUV energy from 0 to 45 nm that produces the far ultraviolet (FUV) terrestrial dayglow observed by the Global Ultraviolet Imager (GUVI). However, the spectral structure of this third component is complex, and its origin is uncertain. Analogous two-and three-component models are also developed with absolute scales determined by the NRLEUV2 spectrum of the quiet Sun rather than by the SEE average spectrum. Assessment of the EUV absolute spectrum and variability of the four different models indicate that during solar cycle 23, the EUV irradiance (0 to 120 nm) increased 100 ± 30%, from 2.9 ± 0.2 to 5.8 ± 0.9 mWm −2 , and may have been as low as 1.9 ± 0.5 mWm −2 during the 17th-century Maunder Minimum. Near the peak of upcoming solar cycle 24, EUV irradiance is expected to increase 40% to 80% above the 2008 minimum values.

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“…Effects of radiative transfer are apparent at least up to Lyλ, and the lines Lyβ to Ly are selfreversed, because the line centres are absorbed at higher altitudes. The strongly self-reversed Lyα and Lyβ lines and their variations during solar cycle 23 have been studied by Lemaire Korendyke and A. Vourlidas) et al (1998,2005) using the scattered full-disk radiation in the SUMER telescope and calibrating it with the help of the Solar-Stellar Irradiance Comparison Experiment (SOLSTICE) measurements (Woods et al 2000). For the interaction of the cool hydrogen in our planetary system with the solar Lyα radiation, the spectral irradiance at the line centre is of particular importance.…”

Section: The Lyman Lines Of Hydrogen and The Continuummentioning

confidence: 99%

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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Improved solar Lyman α irradiance modeling from 1947 through 1999 based on UARS observations

Cited by 335 publications

References 59 publications

Physical parameters of a mid-latitude streamer during the declining phase of the solar cycle

Physical parameters of a mid-latitude streamer during the declining phase of the solar cycle

Solar extreme ultraviolet irradiance: Present, past, and future

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

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