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Causes of low thermospheric density during the 2007-2009 solar minimum
Woods, Thomas N.; Didkovsky, Leonid V.; Solomon, Stanley C. +2 more
Satellite drag data indicate that the thermosphere was lower in density, and therefore cooler, during the protracted solar minimum period of 2007-2009 than at any other time in the past 47 years. Measurements indicate that solar EUV irradiance was also lower than during the previous solar minimum. However, secular change due to increasing levels o…
Does the F10.7 index correctly describe solar EUV flux during the deep solar minimum of 2007-2009?
Liu, Libo; Wan, Weixing; Chen, Yiding
This paper shows that the relationship between solar EUV flux and the F10.7 index during the extended solar minimum (Smin) of 2007-2009 is different from that in the previous Smin. This difference is also seen in the relationship between foF2 and F10.7. We collected SOHO/SEM EUV observations and the F
Statistical study of coronal mass ejection source locations: Understanding CMEs viewed in coronagraphs
Wang, Yuming; Shen, Chenglong; Wang, S. +3 more
How to properly understand coronal mass ejections (CMEs) viewed in white light coronagraphs is crucial to many relative researches in solar and space physics. The issue is now particularly addressed in this paper through studying the source locations of all the 1078 Large Angle and Spectrometric Coronagraph (LASCO) CMEs listed in Coordinated Data …
Solar extreme ultraviolet irradiance: Present, past, and future
Meier, R. R.; Lean, J. L.; Evans, J. S. +4 more
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 F10.7 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, annua…
How is open solar magnetic flux lost over the solar cycle?
Owens, M. J.; Crooker, N. U.; Lockwood, M.
The Sun's open magnetic field, magnetic flux dragged out into the heliosphere by the solar wind, varies by approximately a factor of 2 over the solar cycle. We consider the evolution of open solar flux in terms of a source and loss term. Open solar flux creation is likely to proceed at a rate dependent on the rate of photospheric flux emergence, w…
Impact factor for the ionospheric total electron content response to solar flare irradiation
Zhang, W.; Cai, L.; Zhang, D. H. +4 more
On the basis of ionospheric total electron content (TEC) enhancement over the subsolar region during flares, and combined with data of the peak X-ray flux in the 0.1-0.8 nm region, EUV increase in the 0.1-50 and 26-34 nm regions observed by the SOHO Solar EUV Monitor EUV detector, also with the flare location on the solar disc, the relationship am…
Energetic storm particle events in coronal mass ejection-driven shocks
Gopalswamy, N.; Yashiro, S.; Mäkelä, P. +2 more
We investigate the variability in the occurrence of energetic storm particle (ESP) events associated with shocks driven by coronal mass ejections (CMEs). The interplanetary shocks were detected during the period from 1996 to 2006. First, we analyze the CME properties near the Sun. The CMEs with an ESP-producing shock are faster ($\langle$VCME…
Statistical analysis of solar EUV and X-ray flux enhancements induced by solar flares and its implication to upper atmosphere
Le, Huijun; Liu, Libo; Wan, Weixing +1 more
The 0.1-0.8 nm X-ray flux data and 26-34 nm EUV flux data are used to statistically analyze the relationship between enhancement in X-ray flux and that in EUV flux during solar flares in 1996-2006. The EUV enhancement does not linearly increase with X-ray flux from C-class to X-class flares. Its uprising amplitude decreases with X-ray flux. The co…
Statistical study of coronal mass ejection source locations: 2. Role of active regions in CME production
Wang, Yuming; Shen, Chenglong; Wang, S. +3 more
This is the second paper of the statistical study of coronal mass ejection (CME) source locations, in which the relationship between CMEs and active regions (ARs) is statistically studied on the basis of the information of CME source locations and the ARs automatically extracted from magnetic synoptic charts of Michelson Doppler Imager (MDI) durin…
Long-term variation in the thermosphere: TIMED/GUVI observations
Zhang, Y.; Paxton, Larry J.
Long-term changes in the thermospheric composition (O/N2 column density ratio) and exospheric temperature (Texo) have been examined. The data are obtained from TIMED/GUVI disk and limb measurements over half of a solar cycle from 2002 to 2007. The data indicate a positive correlation between O/N2 and solar EUV flux…