Soft X-rays in the 00:18 UT solar flare on April 22, 1994

Kocharov, G. E.; Charikov, Yu. E.; Lazutkov, V. P.; Matveev, G. A.; Nitsora, Yu. N.; Savchenko, M. I.; Skorodumov, D. V.

doi:10.1016/s1464-1917(00)00043-x

Cited by 4 publications

(3 citation statements)

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“…Short-term changes (Fig. 17) are reported in several publications such as by Kocharov et al (2000) and by Schmidtke (1984). Variability of the total EUV flux up to about 25 % is observed on a relative intensity scale.…”

Section: State Of the Art Of Euv-ssi Results At The End Of The 20th Cmentioning

confidence: 70%

Extreme ultraviolet spectral irradiance measurements since 1946

Schmidtke

2015

Hist. Geo Space. Sci.

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Abstract. In the physics of the upper atmosphere the solar extreme ultraviolet (EUV) radiation plays a dominant role controlling most of the thermospheric/ionospheric (T/I) processes. Since this part of the solar spectrum is absorbed in the thermosphere, platforms to measure the EUV fluxes became only available with the development of rockets reaching altitude levels exceeding 80 km. With the availability of V2 rockets used in space research, recording of EUV spectra started in 1946 using photographic films. The development of pointing devices to accurately orient the spectrographs toward the sun initiated intense activities in solar-terrestrial research. The application of photoelectric recording technology enabled the scientists placing EUV spectrometers aboard satellites observing qualitatively strong variability of the solar EUV irradiance on short-, medium-, and longterm scales. However, as more measurements were performed more radiometric EUV data diverged due to the inherent degradation of the EUV instruments with time. Also, continuous recording of the EUV energy input to the T/I system was not achieved. It is only at the end of the last century that there was progress made in solving the serious problem of degradation enabling to monitore solar EUV fluxes with sufficient radiometric accuracy. The data sets available allow composing the data available to the first set of EUV data covering a period of 11 years for the first time. Based on the sophisticated instrumentation verified in space, future EUV measurements of the solar spectral irradiance (SSI) are promising accuracy levels of about 5 % and less. With added low-cost equipment, real-time measurements will allow providing data needed in ionospheric modeling, e.g., for correcting propagation delays of navigation signals from space to earth. Adding EUV airglow and auroral emission monitoring by airglow cameras, the impact of space weather on the terrestrial T/I system can be studied with a spectral terrestrial irradiance camera (STI-Cam) and also be used investigating real-time space weather effects and deriving more detailed correction procedures for the evaluation of Global Navigation Satellite System (GNSS) signals. Progress in physics goes with achieving higher accuracy in measurements. This review historically guides the reader on the ways of exploring the impact of the variable solar radiation in the extreme ultraviolet spectral region on our upper atmosphere in the altitude regime from 80 to 1000 km.

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Section: State Of the Art Of Euv-ssi Results At The End Of The 20th Cmentioning

confidence: 70%

Extreme ultraviolet spectral irradiance measurements since 1946

Schmidtke

2015

Hist. Geo Space. Sci.

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“…The enhancement in ionospheric temperature is mainly due to high energy X-rays and ultraviolet radiation produced during the solar flares (Donnelly, 1976;Charikov, 2000;Kocharov et al, 2000). These high-energy radiation reach the Earth's ionosphere and heat the plasma.…”

Section: Resultsmentioning

confidence: 99%

Enhancement in electron and ion temperatures due to solar flares as measured by SROSS-C2 satellite

et al. 2004

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Abstract. The observations on the ionospheric electron and ion temperatures (T e and T i ) measured by the RPA payload aboard the SROSS-C2 satellite have been used to study the effect of solar flares on ionospheric heating. The data on solar flare has been obtained from the National Geophysical Data Center (NGDC) Boulder, Colorado (USA). It has been found that the electron and ion temperatures have a consistent enhancement during the solar flares on the dayside Earth's ionosphere. The estimated enhancement for the average electron temperature is from 1.3 to 1.9 times whereas for ion temperature it is from 1.2 to 1.4 times to the normal days average temperature. The enhancement of ionospheric temperatures due to solar flares is correlated with the diurnal variation of normal days' ionospheric temperatures. The solar flare does not have any significant effect on the nightside ionosphere. A comparison with the temperature obtained from the IRI-95 model also shows a similar enhancement.

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“…Typical examples are presented for short-term (up to 15 min, see example in Fig. 8 and Kocharov et al 17 ) and medium-term (near 27 days; Fig. 9(a) by Hall and Hinteregger 15 and about two solar rotations in Fig.…”

Section: What Did We Learn From Euv Ssi Space Measurements Of the Pasmentioning

confidence: 98%

History of extreme ultraviolet solar measurements in XX–XXI centuries: from balloons to the International Space Station as instrumental platforms

Schmidtke

2015

J. Opt. Technol.

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The Sun was one of the central points for observations as long as human cultures are known. After researchers observed the extension of the solar rainbow spectrum towards shorter wavelengths with increasing altitude they started measurements of the solar ultraviolet spectrum from balloons in 1934. The acquisition of spectra in the extreme ultraviolet and soft X-ray spectral regions was beginning after 1946 using photographic recordings aboard rockets. However, it took six more years to achieve good spectral resolution below about 220 nm because servomechanisms had to be developed to fairly accurately point the spectrographs to the Sun during the rocket flight. Another big step forward was achieved by the application of photoelectric recording technology and by using satellites as a platform to observe qualitatively the strong variability of the solar ultraviolet irradiance on short-, medium-and long-term scales. Until the end of the past century these measurements have been strongly impeded by the inherent degradation of the EUV instruments with time. Since there is progress solving this serious problem, measurements with sufficient radiometric accuracy allow composing the data available to the first set of ultraviolet data covering a period of eleven years. Based on the sophisticated instrumentation verified in space, future EUV measurements of the solar spectral irradiance on the International Space Station are promising accuracy levels of about 5%. Added by low-cost equipment on-line measurements will allow providing data needed in ionospheric modeling for correcting propagation delays of navigation signals from space to Earth. Adding ultraviolet airglow and auroral emission measurements the impact of space weather on the ionosphere can be studied and also be used deriving more detailed correction procedures for the evaluation of Global Navigation Satellite System (GNSS) signals.

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Soft X-rays in the 00:18 UT solar flare on April 22, 1994

Cited by 4 publications

References 1 publication

Extreme ultraviolet spectral irradiance measurements since 1946

Extreme ultraviolet spectral irradiance measurements since 1946

Enhancement in electron and ion temperatures due to solar flares as measured by SROSS-C2 satellite

History of extreme ultraviolet solar measurements in XX–XXI centuries: from balloons to the International Space Station as instrumental platforms

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