Ionization frequencies for solar cycle 21: Revised

Torr, Marsha R.; Torr, D. G.

doi:10.1029/ja090ia07p06675

Cited by 227 publications

(71 citation statements)

References 13 publications

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“…Other levels of activity are modelled by interpolating the decimetric radio index f 10.7 . The set of data used to determine the flux has been gradually improved (Hinteregger 1981;Hinteregger and Katsura 1981;Torr and Torr 1985). Tobiska (1991Tobiska ( , 1993 and Tobiska and Eparvier (1998) developed a different model, called EUV, using a more extended data base.…”

Section: Solar Xuv-euv Models For Space Weather Applicationsmentioning

confidence: 99%

“…Following this model, quantitative assessment of solar activity observations and forecasts over 27 years (from 1980 to 2006) indicates that the chromospheric Mg index is superior to the coronal f 10.7 radio flux, both as a proxy for the day-to-day EUV irradiance variations that drive density changes and as an input to empirical models for density forecasts. Torr and Torr (1979), Hinteregger (1981), Hinteregger and Katsura (1981), Torr and Torr (1985) Analysis , Warren (2006) A n a l y s i s All these models are useful tools for space weather studies and are used in operations for tracking solar activity. Shortcomings of the models include uncertainties from using proxies to span the spectral irradiance data gaps and inability to represent all solar conditions (Dudok de Wit et al 2005).…”

Section: Solar Xuv-euv Models For Space Weather Applicationsmentioning

confidence: 99%

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Solar Weather Event Modelling and Prediction

et al. 2009

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Key drivers of solar weather and mid-term solar weather are reviewed by considering a selection of relevant physics-and statistics-based scientific models as well as a selection of related prediction models, in order to provide an updated operational scenario for space weather applications. The characteristics and outcomes of the considered scientific and prediction models indicate that they only partially cope with the complex nature of solar activity for the lack of a detailed knowledge of the underlying physics. This is indicated by the fact that, on one hand, scientific models based on chaos theory and non-linear dynamics reproduce better the observed features, and, on the other hand, that prediction models based on statistics and artificial neural networks perform better. To date, the solar weather prediction success at most time and spatial scales is far from being satisfactory, but the forthcoming ground-and space-based high-resolution observations can add fundamental tiles to the modelling and predicting frameworks as well as the application of advanced mathematical approaches in the analysis of diachronic solar observations, that are a must to provide comprehensive and homogeneous data sets.

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Section: Solar Xuv-euv Models For Space Weather Applicationsmentioning

confidence: 99%

Section: Solar Xuv-euv Models For Space Weather Applicationsmentioning

confidence: 99%

Solar Weather Event Modelling and Prediction

et al. 2009

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“…The solar flux used in the photolysis calculations comes from results of satellite and/or rocket measurements at solar minimum reported by Torr and Torr (1985) for A. ::::; 1035 A and Mount and Rottman (1983) for A.~ 1190A. At Lyman alpha, A.= 1215.7 A, the solar flux at 1 AU distance from the sun was set to a value of 2.2210 11 photons cm -i s-1 (R. Clancy, private communication, 1986) as observed by the Solar Mesosphere Explorer satellite (SME; Rottman et al, 1982) on the day of the Giotto encounter with Halley.…”

Section: Introductionmentioning

confidence: 99%

Evidence for methane and ammonia in the coma of comet P/Halley

Allen

Delitsky

Huntress

et al. 1988

Exploration of Halley’s Comet

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Summary. Methane and ammonia abundances in the coma of Halley are derived from Giotto IMS data using an Eulerian model of chemical and physical processes inside the contact surface to simulate Giotto HIS ion mass spectral data for mass-to-charge ratios (m/q) from 15 to 19. The ratio m/q = 19/18 as a function of distance from the nucleus is not reproduced by a model for a pure water coma. It is necessary to include the presence of NH 3 , and uniquely NH 3 , in coma gases in order to explain the data. A ratio of production rates Q(NH3)/Q(H20) = 0.01-Q.02 results in model values approximating the Giotto data. Methane is identified as the most probable source of the distinct peak at m/q = 15. The observations are fit best with Q(CH4 )/Q(H2 0) = 0.02. The chemical composition of the comet nucleus implied by these production rate ratios is unlike that of the outer planets. On the other hand, there are also significant differences from observations of gas phase interstellar material.

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“…7. The model for the solar intensity¯ux (Torr and Torr, 1985). The thin line is for solar maximum (F10.7 = 243) and the thick line for solar minimum (F10.7 = 68).…”

Section: Intensity Analysismentioning

confidence: 99%

“…Figure 7 shows the model for the solar intensity¯ux spectrum (Torr and Torr, 1985) we basically used. The solar intensity for any F10.7 is deduced by interpolation between the two referencē uxes of Fig.…”

Section: Intensity Analysismentioning

confidence: 99%

Effect of suprathermal electrons on the intensity and Doppler frequency of electron plasma lines

Guio

Lilensten

1999

Ann. Geophys.

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Abstract. In an incoherent scattering radar experiment, the spectral measurement of the so-called up-and downshifted electron plasma lines provides information about their intensity and their Doppler frequency. These two spectral lines correspond, in the backscatter geometry, to two Langmuir waves travelling towards and away from the radar. In the daytime ionosphere, the presence of a small percentage of photoelectrons produced by the solar EUV of the total electron population can excite or damp these Langmuir waves above the thermal equilibrium, resulting in an enhancement of the intensity of the lines above the thermal level. The presence of photo-electrons also modi®es the dielectric response function of the plasma from the Maxwellian and thus in¯uences the Doppler frequency of the plasma lines. In this paper, we present a high time-resolution plasma-line data set collected on the EISCAT VHF radar. The analysed data are compared with a model that includes the e ect of a suprathermal electron population calculated by a transport code. By comparing the intensity of the analysed plasma lines data to our model, we show that two sharp peaks in the electron suprathermal distribution in the energy range 20±30 eV causes an increased Landau damping around 24.25 eV and 26.25 eV. We have identi®ed these two sharp peaks as the e ect of the photoionisation of N 2 and O by the intense¯ux of monochromatic HeII radiation of wavelength 30.378 nm (40.812 eV) created in the chromospheric network and coronal holes. Furthermore, we see that what would have been interpreted as a mean Doppler drift velocity for a Maxwellian plasma is actually a shift of the Doppler frequency of the plasma lines due to suprathermal electrons.

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Ionization frequencies for solar cycle 21: Revised

Cited by 227 publications

References 13 publications

Solar Weather Event Modelling and Prediction

Solar Weather Event Modelling and Prediction

Evidence for methane and ammonia in the coma of comet P/Halley

Effect of suprathermal electrons on the intensity and Doppler frequency of electron plasma lines

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