The height structure of solar active regions at X-ray wavelengths as deduced from OSO-8 limb crossing observations

Mosher, J. M.

doi:10.1007/bf00151119

Cited by 17 publications

(7 citation statements)

References 8 publications

(2 reference statements)

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“…The large difference between the results in Figures 3a and 3b suggests that the thermosphere responds differently depending on flare location on the disk. It is known that X‐ray flux intensity is independent of solar origin location [e.g., Mosher , 1979; Samain , 1979]. Their results indicated that the EUV and UV radiation intensity decreases when a radiation source moves from the central solar meridian to the limb, whereas the intensity of soft X rays remains almost unchanged.…”

Section: Resultsmentioning

confidence: 99%

An analysis of thermospheric density response to solar flares during 2001–2006

Liu

Wan

2012

J. Geophys. Res.

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[1] Previous studies show there are significant thermospheric responses to the two great solar flares on October 28, 2003 (X17.2) and November 4, 2003 (X28). In the present study, we further explored the thermospheric response to all X-class solar flares during [2001][2002][2003][2004][2005][2006]. The observed results show that X5 and stronger solar flares can induce an average enhancement of 10-13% in thermospheric density in latitude 50 S-50 N within $4 h after the flare onset. Many important lines and continua in solar EUV region are optically thick, thus EUV enhancements are smaller for flares located near the solar limb due to absorption by the solar atmosphere. Limb flares induce smaller thermospheric responses, due to the limb effect of solar EUV. The thermospheric density enhancement is much more correlated with integrated EUV flux than with peak EUV flux, with a high correlation coefficient of 0.91, which suggests that thermospheric response is strongly dependent on the total integrated energy into the thermosphere.

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Section: Resultsmentioning

confidence: 99%

An analysis of thermospheric density response to solar flares during 2001–2006

Liu

Wan

2012

J. Geophys. Res.

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“…where is the radius of the cross section of the Sun and P R 0 is the rotation period at the latitude of the active region (e.g., Mosher 1979 ;Sterling et al 1996). NOAA AR 7999 was near the equator (latitude 4¡ S), and so equation (2) reduces to H B 37t2, with H in km and t in hours.…”

Section: Results : Cds Image Ratiosmentioning

confidence: 99%

“…Mason & Pike (1998) studied an active region near the limb with CDS and found that the hottest, densest part was very low lying (\20,000 km). Much earlier, Mosher (1979) found a decreasing temperature with height trend using active region limb crossing X-ray data from the OSO-8 satellite. Also, Cheng, Smith, & Tandberg-Hanssen (1980), using Skylab XUV and X-ray data, found the brightest hot coronal active region loops to be mostly low lying and compact and cooler (transition zone) loops to be larger.…”

Section: Introductionmentioning

confidence: 92%

Variation of Thermal Structure with Height of a Solar Active Region Derived fromSOHOCDS andYOHKOHBCS Observations

Sterling

Pike

Mason

et al. 1999

ApJ

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We present observations of NOAA solar Active Region 7999 when it was near the west solar limb on 1996 December 2 and 3, using data from the Coronal Diagnostic Spectrometer (CDS) experiment on the SOHO satellite. Ratios of intensities of 2 MK material (as observed in CDS Fe XVI images) to 1 MK material (from CDS Mg IX images) indicate that there is a drop in the ratio of the hotter to the cooler material with height in the region, up to an altitude of about 105 km. At low altitudes the relative amount of 2 MK emission measure to 1 MK emission measure ranges from 8 to 10, while the ratio is minimum near 105 km, ranging from 1.3 to 3.5. The decrease with height of the CDS ratio qualitatively resembles the decrease in S XV election temperature with height (measurable up to B85,000 km) in the same active region obtained from the Bragg crystal spectrometer instrument on Y ohkoh. The CDS images indicate that the highest S XV temperatures and largest CDS ratios correspond to regions of microÑares, and somewhat lower S XV temperatures and CDS ratios correspond to di †use regions. Above 105 km, the trend of the CDS ratios changes, either increasing or remaining approximately constant with height. At these altitudes the CDS images show faint, large-scale di †use structures.

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“…Fig. 6a presents the appropriate dependencies of X-ray flux emission intensities (Mosher, 1979), F10 cm (Riddle, 1969;Vauquois, 1955), and UV (Samain, 1979).…”

Section: Discussionmentioning

confidence: 99%

Ionospheric effects of the solar flares as deduced from global GPS network data

Afraimovich¹,

Altynsev²,

Grechnev³

et al. 2001

Advances in Space Research

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Results derived from analysing the ionosphere response to faint and bright solar flares are presented. The analysis used technology of a global detection of ionospheric effects from solar flares as developed by the authors, on the basis of phase measurements of the total electron content (TEC) in the ionosphere using an international GPS network. The essence of the method is that use is made of appropriate filtering and a coherent processing of variations in the TEC which is determined from GPS data, simultaneously for the entire set of visible GPS satellites at all stations used in the analysis. This technique is useful for identifying the ionospheric response to faint solar flares (of X-ray class C) when the variation amplitude of the TEC response to separate line-on-sight to GPS satellite is comparable to the level of background fluctuations. The dependence of the TEC variation response amplitude on the flares location on the Sun is investigated.

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The height structure of solar active regions at X-ray wavelengths as deduced from OSO-8 limb crossing observations

Cited by 17 publications

References 8 publications

An analysis of thermospheric density response to solar flares during 2001–2006

An analysis of thermospheric density response to solar flares during 2001–2006

Variation of Thermal Structure with Height of a Solar Active Region Derived fromSOHOCDS andYOHKOHBCS Observations

Ionospheric effects of the solar flares as deduced from global GPS network data

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