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1.
The dissimilarity of the results of solar and galactic proton flux measurements made on different spacecraft is pointed out. It is caused, in addition to instrument errors, by differences in the temporal and spatial conditions of the measurements. We suggest using statistical analysis of proton fluences calculated for different long time intervals, from half a year to 10 years, for the optimization of the interplanetary proton database. An example of such analysis is presented and a probabilistic model of total proton fluences at the Earth’s orbit outside the magnetosphere, constructed using the analysis, is described. A formalized method for separating proton fluxes in solar proton events from protons of galactic cosmic rays is suggested. A conclusion is made that sources of cosmic ray protons with energies of less than 4 MeV should be examined in more detail. 相似文献
2.
The solar proton event (SPE) may become a serious threat to the cosmonautical activities of human beings, so the prediction of the flux of solar protons within a certain period has important guiding significance for the projection of the anti-radiation solidification of space vehicles. On the basis of a statistical analysis of the data of SPEs in the 20th to 23rd cycles of solar activity, a new model of solar proton fluxes with E > 10 MeV and E > 30 MeV is established. In comparison with the JPL model, which is frequently adopted in the present aerospace engineering, the influence factor of solar activity on the occurrence of proton events is introduced, and it can be used to estimate the proton fluxes under various levels of solar activity. The results can better match the characteristics of the distribution of proton events. 相似文献
3.
The energy spectra of protons at energies in the range of about 1–100 MeV are investigated during time periods of low solar activity using data sets from near Earth spacecraft. These populations pose a tough experimental and theoretical problem that remains unsolved up to now. We attempt to provide a consistent definition of low-flux quiet-time periods relevant to low solar activity as well as quasi-stationary periods useful at higher levels of solar activity. Using statistical methods, the possible instrumental contribution to the lowest observed proton fluxes for various detectors is estimated. We suggest and prove that there exists a low-flux population of charged particles in the energy range of about 1–10 MeV, which is present in the inner heliosphere even during the quietest conditions at lowest solar activity. The dynamics of the variations of proton spectra over the solar cycle is investigated. A series of low-flux periods is examined in detail and energy spectra of protons are approximated in the form of J(E)=AE
–+CE. By determining the best fitting parameters to the energy spectra correlations are made among them as well as with monthly sunspot numbers characterizing solar activity. It has been demonstrated that the value of the energy minimum of proton spectrum E
min that `divides' the two populations – `solar/heliospheric' and `galactic' – is shifted towards higher values with increasing solar activity. Protons have been argued to be predominantly of solar origin up to several MeV near the solar cycle minimum and up to 20–30 MeV at maximum. The slope of the lower spectrum branch (parameter ) slightly decreases with increasing solar activity. The minimum fluxes observed during the last 3 minima of solar activity are compared; the lowest fluxes were those during the 1985–1987 period. 相似文献
4.
A summary of major solar proton events 总被引：9，自引：0，他引：9
Solar proton events have been routinely detected by satellites since the 20th solar cycle; however, before that time only very major proton events were detected at the Earth. Even though the detection thresholds differed between the 19th and more recent cycles, more than 200 solar proton events with a flux of over 10 particles (cm2 s ster)–1 above 10 MeV have been recorded at the Earth in the last three solar cycles. At least 15% of these events had protons with energies greater than 450 MeV detected at the Earth. Other than an increase in solar proton event occurrence with increasing solar cycle, no recognizable pattern could be identified between the occurrence of solar proton events and the solar cycle. The knowledge we have gained from the data acquired over the past 40 years illustrates the difficulty in extrapolating back in time to infer the number and intensity of major solar proton events at the Earth.The U.S. Government retains a nonexclusive, royalty-free license to publish or reproduce the published form of this contribution, or allow others to do so, for U.S. Government purposes. 相似文献
5.
A. B. Struminsky 《Astronomy Letters》2006,32(10):688-697
We analyze the observations of solar protons with energies >80 MeV near the Earth and the January 20, 2005, solar flare in various ranges of the electromagnetic spectrum. Within approximately the first 30 min after their escape into interplanetary space, the solar protons with energies above 80 MeV propagated without scattering to the Earth and their time profiles were determined only by the time profile of the source on the Sun and its energy spectrum. The 80–165 MeV proton injection function was nonzero beginning at 06:43:80 UT and can be represented as the product of the temporal part, the ACS (Anticoincidence System) SPI (Spectrometer on INTEGRAL) count rate, and the energy part, a power-law proton spectrum ～E ?4.7±0.1. Protons with energies above 165 MeV and relativistic electrons were injected, respectively, 4 and 9 min later than this time. The close correlation between high-energy solar electromagnetic emission and solar proton fluxes near the Earth is evidence for prolonged and multiple proton acceleration in solar flares. The formation of a posteruptive loop system was most likely accompanied by successive energy releases and acceleration of charged particles with various energies. Our results are in conflict with the ideas of cosmic-ray acceleration in gradual solar particle events at the shock wave driven by a coronal mass ejection. 相似文献
6.
We revisited assessments of the occurrence probability distribution of large events in solar energetic particles (SEP), based on measurements of cosmogenic radionuclides in lunar rocks. We present a combined cumulative occurrence probability distribution of SEP events based on three timescales: directly measured SEP fluences for the past 60 years; estimates based on the terrestrial cosmogenic radionuclides 10Be and 14C for the multi-millennial (Holocene) timescale; and cosmogenic radionuclides measured in lunar rocks on a timescale of up to 1 Myr. These three timescales yield a consistent distribution. The data suggest a strong roll-over of the occurrence probability, so that SEP events with a proton fluence with energy >?30 MeV greater than 1011 (protons cm?2?yr?1) are not expected on a Myr timescale. 相似文献
7.
This paper presents directional low energy solar proton measurements together with inter-planetary magnetic field measurements. Propagation of 1 to 13 MeV solar protons is discussed in terms of the relative importance of field-aligned streaming compared to convection of the proton population in the solar wind. Evidence is presented to show that protons associated with the January 24, 1969 solar flare were stored near the Sun for at least 90 minutes. It is also shown that under favourable conditions solar protons can be accelerated near the Earth's bow shock. The decay of solar protons is shown to be mainly convective; however, there are indications that in smooth field regimes convection of 1 MeV solar protons can be greatly reduced. Finally, it is pointed out that the effect of adiabatic deceleration can be quite important. 相似文献
8.
Power-law distribution for solar energetic proton events 总被引：1，自引：0，他引：1
Analyses of the time-integrated fluxes of solar energetic particle events during the period 1965–1990 show that the differential distribution of events with flux F is given by a power law, with indices between 1.2 and 1.4 depending on energy. The power law represents a good fit over three to four orders of magnitude in fluence. Similar power-law distributions have been found for peak proton and electron fluxes, X-ray flares and radio and type III bursts. At fluences greater than 109 cm–2, the slope of the distribution steepens and beyond 1010 cm–2 the power-law index is estimated to be 3.5. At energies greater than 10 MeV, the slope of the distribution was found to be essentially independent of solar cycle, when the active years of solar cycles 20, 21, and 22 were analysed. The results presented are the first for a complete period of 27 years, covering nearly 3 complete solar cycles. Other new aspects of the results include the invariance of the exponent with solar cycle and also with integral energy. 相似文献
9.
The advent of new and better instruments in space has resulted in a considerable increase in the number of solar gamma-ray events (GRE) detected. In this paper, we analyze available SMM/GRS and GRANAT/PHEBUS data on the hard X-ray and gamma-ray events, and their associations with solar proton events (SPE) at the Earth's orbit, for the observation period of 1980–1995. About 58% of the GREs under study were found to be SPE-related ones. Size (frequency) distributions have been obtained, for the first time, for the events with different types of emissions (bremsstrahlung, narrow GR lines, positron annihilation line, neutron capture line, SPEs, etc.). We discuss the possible relationships between size distributions implied by the parameter correlation. The distribution for GR events turns out to be generally harder than that for X-ray bursts. The GREs involving energetic particles in space are shown to have a harder frequency distribution in comparison with that for GREs without detectable SPEs. There is also a tendency for the GREs with highest fluences to be related with SPEs. Finally, no correlation seems to exist between the GRL fluence and maximum flux of >10 MeV protons near the Earth. 相似文献
10.
Probhas Raychaudhuri 《Solar physics》1994,153(1-2):445-448
We have studied Forbush decreases (FD) with solar flare data and major solar proton event (SPE) data (E > 10 MeV) for the years 1976–1986 and have found that FD solar flare data exhibit periods around 0.95, 2.4, and 4.75 years at >99% level of confidence (CL), while SPE data exhibit periods around 2.6 and 5.0 years (at >95% CL). Because of a common periodicity around 2.5 years, it is suggested that FD with the solar flare data and major SPE data, together with solar diameter and solar neutrino variations, behave similarly and may have a common origin. 相似文献
11.
Y. Hakura 《Solar physics》1974,39(2):493-497
Long-term variation in energetic particle emissivity of the sun was examined by the use of PCA, solar proton flux, and geomagnetic data from 1941 to 1973. A solar cycle may be divided into three periods in terms of the Sun's particle emissivity. The first period with a peak of emissivity coinciding with the maximum of Zurich sunspot numbers is characterized by the random occurrence of proton flares along the heliographic longitude. On the other hand, active centers were restricted in certain longitude regions and had a tendency to produce a series of major flares in a week or two during the second period. The peak of particle emissivity in this period occurred a few years after the first. Relativistic proton events were observed during both the periods of enhanced particle emissivity. In the third period near the end of the solar cycle, MeV proton events of 27-days recurrency became predominating, though particle emissivity of the Sun itself was relatively low. 相似文献
12.
Kunitomo Sakurai 《Planetary and Space Science》1973,21(5):793-798
This paper discusses the relationship between some characteristics of microwave type IV radio bursts and solar cosmic ray protons of MeV energy. It is shown that the peak flux intensity of those bursts is almost linearly correlated with the MeV proton peak flux observed by satellites near the Earth and that protons and electrons would be accelerated simultaneously by a similar mechanism during the explosive phase of solar flares.Brief discussion is given on the propagation of solar cosmic rays in the solar envelope after ejection from the flare regions. 相似文献
13.
G. Kremser H. Specht E. Kirsch K.H. Saeger W. Riedler 《Planetary and Space Science》1977,25(9):823-831
Measurements by balloon-borne instruments, data from the satellites Explorer 41 and 43 and riometer recordings were used to investigate the influence of magnetospheric processes on the precipitation of energetic solar protons related to the occurrence of two ssc's on 8–9 August 1972. The high-energy protons (Ep ? 30 MeV) had direct access to auroral-zone latitudes. The flux variations of low-energy (some MeV) protons in interplanetary space and the magnetosphere were different from those of the protons precipitated in the auroral zone. These low-energy protons were precipitated mainly during and after the ssc's. The importance of direct proton access, radial diffusion, pitch angle scattering and proton acceleration for the explanation of the low-energy proton behaviour is discussed. 相似文献
14.
Electron-dominated episodes or events during solar flares are characterized by a flattening of the electron bremsstrahlung continuum above about 1 MeV. This flattening leads to a dominance of the continuum at MeV energies over nuclear emissions. We analyzed events recorded by the gamma-ray spectrometer on SMM with the aim to determine the nuclear contribution in the energy range between 4 and 8 MeV. We find that for comparable continuum fluences it is less by about an order of magnitude than for other flares. The spectral index of the best-fit power law of the > 1 MeV continuum with a median at –1.84 turns out to be independent of the heliocentric angle of the events, implying that the degree of anisotropy of the radiating particles was low. It is of interest to note that a value of –1.5 seems to be a limit. The spectral index of the continuum between 0.3 and 1 MeV does not differ significantly from that of other flares. Only measurements with detectors sensitive up to at least 10 MeV can, therefore, sort out electron dominated episodes during solar flares. 相似文献
15.
G. Chambon K. Hurley M. Niel R. Talon G. Vedrenne I. V. Estuline O. B. Likine 《Solar physics》1981,69(1):147-159
The November 22, 1977 solar flare was observed at energies up to 4.9 MeV by French-built gamma ray detectors aboard the Soviet Prognoz-6 satellite. The data show evidence for 2.23 and 4.43 MeV line emission, with the 2.23 MeV emission occurring about 3 min after the flare onset in hard X-rays. The line intensities, 0.11 cm–2s–1 and 0.06 cm–2s–1 for the 2.23 and 4.43 lines, respectively, are roughly comparable to intensities observed in other events. Particle detectors aboard the Prognoz-6 satellite, however, recorded a proton flux much lower than that observed for the 4 August 1972 event. It is shown that this may be taken as evidence for a thick target interpretation of the proton interactions in the solar atmosphere. 相似文献
16.
A database combining information about solar proton enhancements (SPEs) near the Earth and soft X-ray flares (GOES measurements)
has been used for the study of different correlations through the period from 1975 to May 2006. The emphasis of this work
is on the treatment of peak-size distributions of SXR flares and SPEs. The frequency of SXR flares and solar proton events
(>10 and >100 MeV, respectively) for the past three solar cycles has been found to follow mainly a power-law distribution
over three to five orders of magnitude of fluxes, which is physically correct beyond the “sensitivity” problem with the smallest
peak values. The absence of significant spectral steepening in the domain of the highest peak values demonstrates that during
the period considered, lasting 30 years, the limit of the highest flare’s energy release has not yet been achieved. The power-law
exponents were found to be −2.19±0.04, −1.34±0.02, and −1.46±0.04, for the total SXR flare distribution and the total SPE
distributions (for both E
P>10 MeV and E
P>100 MeV), respectively. For SPEs associated with flares located to the West of 20° W, the exponents are −1.22±0.05 (E
P>10 MeV) and −1.26±0.03 (E
P>100 MeV). The size distribution for corresponding flares follows a power law with a slope of −1.29±0.12. Thus, X-ray and
proton fluxes produced in the same solar events have very similar distribution shapes. Moreover, the derived slopes are not
incompatible with a linear dependence between X-ray flare power and proton fluxes near the Earth. A similar statistical relation
is obtained independently from the direct comparison of the X-ray and proton fluxes. These all argue for a statistically significant
relationship between X-ray and proton emissions. 相似文献
17.
S. O. Ifedili 《Solar physics》1974,39(1):233-241
The upper limit on the solar neutron flux from 1–20 MeV has been measured, by a neutron detector on the OGO-6 satellite, to be less than 5 × 10–2 n cm–2 s–1 at the 95% confidence level for several flares including two flares of importance 3B and a solar proton event of importance 3B. The measurements are consistent with the models proposed by Lingenfelter (1969) and by Lingenfelter and Ramaty (1967) for solar neutron production during solar flares. The implied upper limit on the flux of 2.2 MeV solar gamma rays is about the same as the 2.2 MeV flux observed by Chupp et al. (1973). 相似文献
18.
I. G. Richardson T. T. von Rosenvinge H. V. Cane E. R. Christian C. M. S. Cohen A. W. Labrador R. A. Leske R. A. Mewaldt M. E. Wiedenbeck E. C. Stone 《Solar physics》2014,289(8):3059-3107
Using observations from the High Energy Telescopes (HETs) on the STEREO A and B spacecraft and similar observations from near-Earth spacecraft, we summarize the properties of more than 200 individual >?25 MeV solar proton events, some detected by multiple spacecraft, that occurred from the beginning of the STEREO mission in October 2006 to December 2013, and provide a catalog of these events and their solar sources and associations. Longitudinal dependencies of the electron and proton peak intensities and delays to onset and peak intensity relative to the solar event have been examined for 25 three-spacecraft particle events. Expressed as Gaussians, peak intensities fall off with longitude with σ=47±14° for 0.7?–?4 MeV electrons, and σ=43±13° for 14?–?24 MeV protons. Several particle events are discussed in more detail, including one on 3 November 2011, in which ～?25 MeV protons filled the inner heliosphere within 90 minutes of the solar event, and another on 7 March 2012, in which we demonstrate that the first of two coronal mass ejections that erupted from an active region within ～?1 hour was associated with particle acceleration. Comparing the current Solar Cycle 24 with the previous cycle, the first >?25 MeV proton event was detected at Earth in the current solar cycle around one year after smoothed sunspot minimum, compared with a delay of only two months in Cycle 23. Otherwise, solar energetic particle event occurrence rates were reasonably similar during the rising phases of Cycles 23 and 24. However, the rate declined in 2013, reflecting the decline in sunspot number since the peak in the northern-hemisphere sunspot number in November 2011. Observations in late 2013 suggest that the rate may be rising again in association with an increase in the southern sunspot number. 相似文献
19.
The solar flare of November 4, 2001, at 16.03–16.57 UT (GOES soft X-ray class X1.0, optical importance 3B, and coordinates N06W180) is used as an example to investigate the relationship between sporadic VHF radio bursts and charged particle fluxes (of both solar and magnetospheric origins) at an altitude of 500 km. The radio background intensity was recorded at frequencies of 280, 300, 151, and 500 MHz by nondirectional ground-based mid-latitude radio antennas spaced ～700 km apart. The results of our radio measurements are compared with the dynamics of 0.2–12 MeV electron and 1–5 MeV proton fluxes based on data from the MKL instrument onboard the CORONAS-F satellite (the orbit altitude and inclination are 500 km and 82.5°, respectively). 相似文献
20.
We summarize ERNE/SOHO observations of solar energetic particle events associated with impulsive soft X-ray flares and LASCO coronal mass ejections (CMEs). The new observational data support an idea that the >10 MeV proton acceleration may be initiated at different coronal sources, operating in the flaring active region and on the global coronal scale, in concert with CME development. However, the particle acceleration continues beyond the coronal scales and may culminate at the interplanetary CME well after the flare. We emphasize the importance of CME liftoff/aftermath processes in the solar corona and the possible role of seed particle re-acceleration, which may explain the existence of hybrid solar energetic particle events. 相似文献