GNSS measurement of EUV photons flux rate during strong and mid solar flares

Hernández‐Pajares, Manuel; García-Rigo, Alberto; Zornoza, José Miguel Juan; Sanz, J.; Monte, Enric; Aragón‐Àngel, Àngela

doi:10.1029/2012sw000826

Cited by 42 publications

(70 citation statements)

References 26 publications

(31 reference statements)

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“…Since EUV bands are optically thick in the solar atmosphere, flares originating closer to the center of the solar disk are more geo‐effective than those closer to the limb [ Qian et al , ]. Sometimes, after the arrival of a solar flare radiation, associated nearly relativistic electrons can also arrive, typically several minutes after the onset of the EM signature of the solar flare [ Simnett , ; Hernández‐Pajares et al , , Figure 6], which may affect the readings of direct sensors such as the SOHO solar EUV monitor (SEM). But since these electrons enter the Earth's atmosphere through the polar caps, the associated increase in ionization in the atmosphere does not follow the expected flare over ionization dependence of the solar zenith angle, and then it can be filtered out.…”

Section: Introductionmentioning

confidence: 99%

“…In the following sections we will show how solar flares can be monitored using GPS data and how the high geo‐effectiveness of solar EUV radiation allows for the determination of its flux rate by measuring the ionospheric response to solar flares. A previous study by Hernández‐Pajares et al [] on this subject mainly focused and demonstrated the approach, for X class flares. Recently, this GNSS‐ionospheric proxy of the solar EUV flux rate has been used to characterize the main statistical properties of solar flares [ Monte‐Moreno and Hernández‐Pajares , ].…”

Section: Introductionmentioning

confidence: 99%

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GPS as a solar observational instrument: Real‐time estimation of EUV photons flux rate during strong, medium, and weak solar flares

et al. 2015

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In this manuscript, the authors show how the Global Navigation Satellite Systems, GNSS (exemplified in the Global Positioning System, GPS), can be efficiently used for a very different purpose from that for which it was designed as an accurate Solar observational tool, already operational from the open global GPS measurements available in real‐time, and with some advantages regarding dedicated instruments onboard spacecraft. The very high correlation of the solar extreme ultraviolet (EUV) photon flux rate in the 26–34 mm spectral band, obtained from the solar EUV monitor instrument onboard the SOHO spacecraft during Solar flares, is shown with the GNSS solar flare activity indicator (GSFLAI). The GSFLAI is defined as the gradient of the ionospheric vertical total electron content rate versus the cosine of the Solar zenith angle in the day hemisphere (which filters out nonsolar over ionization), and it is measured from data collected by a global network of dual frequency GPS receivers (giving in this way continuous coverage). GSFLAI for 60 X class flares, 320 M class flares, and 300 C class flares, occurred since 2001, were directly compared with the EUV solar flux rate data to show existing correlations. It was found that the GSFLAI and EUV flux rate present the same linear relationship for all classes of flares, not only the strong and medium intensity ones, X and M class, as in previous works, but also for the weakest C class solar flares, which is a remarkable result.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

GPS as a solar observational instrument: Real‐time estimation of EUV photons flux rate during strong, medium, and weak solar flares

et al. 2015

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“…On the basis of the high spatial coverage and good temporal continuity of GPS, some researchers evaluated in detail the global variations of SITEC during solar flares in recent years [e.g., Wan et al ., ; Liu et al ., ; Hernández‐Pajares et al ., ; Xiong et al ., ]. Afraimovich et al .…”

Section: Introductionmentioning

confidence: 99%

Response of the American equatorial and low‐latitude ionosphere to the X1.5 solar flare on 13 September 2005

Xiong

Wan

et al. 2014

JGR Space Physics

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Based on the coordinated observations by the incoherent scatter radar (ISR), ionosonde, magnetometers, and GPS receivers, the electrodynamic effects on the equatorial and low-latitude ionosphere have been investigated during the intense solar flare (X1.5/2B) on 13 September 2005. In the initial stage of the flare, the ISR and ionosonde measurements at Jicamarca show the decreases of 10.14 m/s and 20 km in the upward vertical E × B drift velocity and the F 2 region peak height, respectively, while equatorial electrojet (EEJ) strength over American sector indicates a sudden increase of 53.7 nT. The decrease of the upward vertical E × B drift velocity reveals the weakening of eastward electric field during the flare, which is firstly and directly observed by instrument. It is well known that the variation of equatorial electric field is mainly attributed to the ionospheric dynamo electric field and partially affected by the penetration of interplanetary electric field. The observations during this flare suggest that the flare-induced increase of Cowling conductivity changes the ionospheric dynamo electric field and further results in the weakening of eastward electric field and the decrease of the upward vertical E × B drift velocity. Meanwhile, the upward vertical E × B drift velocity and the EEJ strength during the flare are negatively correlated, which is contrary to the knowledge established by Anderson et al. (2002) based on 10 days of observations in the Peruvian longitude sector. The difference may be caused by the flare-induced enhancement of Cowling conductivity. In addition, GPS total electron content (TEC) observations from six stations in the American equator and low latitudes show an enhancement of 1.47-3.09 TEC units. The measurements of GPS and ISR indicate that the contribution of the enhanced photoionization to the increase of TEC is more than that of electrodynamic effect during the initial stage of the intense flare. IntroductionAs one of the severest solar events, the solar flare is an important topic of solar-terrestrial relations and current space weather research. During a flare, the large and rapid increases of solar X-ray and extreme ultraviolet (EUV) enhance the ionization of the upper atmosphere and cause many kinds of sudden ionospheric disturbances (SIDs). Since 1960s, many researchers have studied different kinds of SIDs, such as sudden cosmic noise absorption (SCNA), sudden enhancement of atmospheric (SEA), sudden phase anomaly (SPA), short wave fadeout (SWF), sudden frequency deviation (SFD), and sudden increase of total electron content (SITEC) [Garriott et al., 1967;Sao et al., 1970;Stonehocker, 1970;Donnelly, 1971;Jones, 1971;Ohshio, 1971;Deshpande and Mitra, 1972;Davies, 1980;Wan et al., 2005]. Previous works have suggested that different disturbed phenomena are attributed to the increase of electron density at different altitudes of ionosphere during flares [e.g., Mendillo and Evans, 1974;Le et al., 2007;Xiong et al., 2011]. The SCNA, SEA, SPA, and SWF are closely relat...

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“…The system also includes two real-time products relying on solar flare nowcasting, which are based on Global Navigation Satellite Systems (GNSS) for monitoring the daylight ionospheric overionization caused by an increase of electromagnetic radiation associated with solar flares: the so-called GNSS Solar Flare Detector (GSFLAD; Hernández-Pajares et al 2012) and the Sunlit Ionosphere Sudden Total Electron Content Enhancement Detector (SISTED; García-Rigo 2012). These products are not used for solar flare or SEP predictions within SEPsFLAREs but can themselves be useful for real-time monitoring of space launch activities, complementing other flare detection products (e.g.…”

Section: System Overviewmentioning

confidence: 99%

Prediction and warning system of SEP events and solar flares for risk estimation in space launch operations

García-Rigo

Núñez

Qahwaji

et al. 2016

J. Space Weather Space Clim.

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A web-based prototype system for predicting solar energetic particle (SEP) events and solar flares for use by space launch operators is presented. The system has been developed as a result of the European Space Agency (ESA) project SEPsFLAREs (Solar Events Prediction system For space LAunch Risk Estimation). The system consists of several modules covering the prediction of solar flares and early SEP Warnings (labeled Warning tool), the prediction of SEP event occurrence and onset, and the prediction of SEP event peak and duration. In addition, the system acquires data for solar flare nowcasting from Global Navigation Satellite Systems (GNSS)-based techniques (GNSS Solar Flare Detector, GSFLAD and the Sunlit Ionosphere Sudden Total Electron Content Enhancement Detector, SISTED) as additional independent products that may also prove useful for space launch operators.

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GNSS measurement of EUV photons flux rate during strong and mid solar flares

Cited by 42 publications

References 26 publications

GPS as a solar observational instrument: Real‐time estimation of EUV photons flux rate during strong, medium, and weak solar flares

GPS as a solar observational instrument: Real‐time estimation of EUV photons flux rate during strong, medium, and weak solar flares

Response of the American equatorial and low‐latitude ionosphere to the X1.5 solar flare on 13 September 2005

Prediction and warning system of SEP events and solar flares for risk estimation in space launch operations

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