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1.
The Fourier analysis of the argon-37 production rate for runs 18–80 observed in Davis's well-known solar neutrino experiment is presented. The method of Fourier analysis with the unequally-spaced data of Davis and associates is described and the discovered periods are compared with recently published results for the analysis of the data of runs 18–69. The harmonic analysis of the data of runs 18–80 shows time variations of the solar neutrino flux with periods =8.33, 5.26, 2.13, 1.56, 0.83, 0.64, 0.54, and 0.50 yr, respectively, which confirms earlier computations. 相似文献
2.
With the gradual accumulation of experimental data in the solar neutrino experiment of DAVIS and collaborators (runs 18–74 for 1970–1982), the question, whether there are time variations of the solar neutrino flux, is of renewed interest. We discuss the mathematical-numerical methods applied to the statistical analysis of DAVIS ' argon-37 production rate up till now known in the literature. These methods are characterized by the arbitrary arrangement of the DAVIS data in a time series. We perform a certain Fourier transformation for unequally-spaced time series of the measuring data of the argon-37 production rate, discuss the discovered periods and give significance criteria with respect to each period. We find that all periods discussed in the literature are contained in our series of periods. Pointing out the more mathematical character of the time series analysis we emphasize the predominant significance of the detected periods. 相似文献
3.
R. P. Kane 《Solar physics》1987,108(2):415-416
Using an earlier correlation analysis between the annual sunspot numbers at sunspot maximum epochs and the minimum annual aa index in the immediately preceding years, the minimum annual aa index (21.6) during 1985–86 implies a maximum annual sunspot number of about 190±40 in the coming solar maximum epoch, in about 1988–89. 相似文献
4.
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
5.
Periodicities of 22, 8 and 6 years have been found by a statistical analysis of the coefficient of atmospheric activity R of Jupiter for the time period 1910–1985.We have also found variations of the coefficient of asymmetry of the activity Z measured by the Observatory of Athens for the time period 1956–1985 with periodicities of 12, 8, 6 and 4 years by statistical analysis.The same periodicities have been recently found in an analysis of the total number of solar flares and in the number of high velocity solar wind streamers. 相似文献
6.
37
Ar production rates from the Homestake experiment suggest a possible anticorrelation between solar neutrino flux and solar activity. In this paper we present results from linear correlation analyses between Homestake data and several solar activity parameters in the period 1970–1990. Our results support the hypothesis that Homestake neutrino fluxes exhibit a (positive or negative) correlation with those parameters, but they also suggest that the heliomagnetic field in the subphotosphere could be responsible for the observed flux modulation. 相似文献
7.
The FOURIER analysis of the measured 37Ar production rate for DAVIS well known solar neutrino experiment shows time variations of the solar neutrino flux with periods of 100.0, 58.8, 35.7, 25.6, 19.6, 15.2, 8.8, and 6.3 months, respectively. We discuss physical assumptions of the standard solar model which are not generally confirmed by observations and trace back the time variations of the neutrino flux with the time scale of the order of years to gravity oscillations of the solar centre. 相似文献
8.
L. Herrera 《Astrophysics and Space Science》1994,215(1):131-133
The eleven-year sunspot cycles are considered to represent one of the solar activities. The daily observations of the sunspots in the KAAU Solar Observatory (KAAUSO) have been utilised to reduce a period of the present solar cycle, using Fourier technique. The highest peak in the amplitude spectrum was for a frequency of 0.00029 day–1, for which the maximum occurred mid 1990. 相似文献
9.
E. S. Dmitrienko 《Astrophysics》1996,39(2):112-114
UBVRI observations of the eclipsing symbiotic star CI Cyg made during 1991–1995 are analyzed, the results of which indicate that the system is in the same quiescent state as during 1985–1990. Variations in the "extra-eclipse" color index U-B with an amplitude of about 0m.3–0m.4 and a characteristic time of about 9–10 yr have been detected for the first time. A more thorough analysis of all available data in the UBVRI bands of the spectrum will be required to investigate the existence of possible long-period variations in the other color indices and brightness of the system.Translated fromAstrofizika, Vol. 39, No. 2, pp. 211–216, April–June, 1996. 相似文献
10.
I. Liritzis 《Solar physics》1995,161(1):29-47
Neutrino capture rate data from the Homestake chlorine experiment (1970–1990) has been spectrally analysed. The data were smoothed by a 4-month equally-spaced sequence and by a cubic spline polynomial approximation. Fourier (FFT), maximum entropy spectrum analysis (MESA), and power spectrum analysis (PSA) employing the Blackman-Tukey window were used. The significant periodicities obtained are: 1 ± 0.1, 1.4 ± 0.2, 2.4 ± 0.2, 5 ± 0.2, and 11 ± 1.5 years. A possible correlation with similar coincident periods in other solar-terrestrial phenomena is discussed. 相似文献
11.
The change in the darkness of the Great Red Spot (GRS) of Jupiter (1894–1974) has been analysed with Fourier (FFT), Maximum Entropy and Power spectrum (Blackman-Tukey window) (PSA) methods of spectrum analysis. Significance, non-randomness and stationarity tests assigned high variance to periodicities of 33 ± 4, 13–15, about 11, 9 and 3 yrs. The highest correlation between solar activity and GRS darkness was found for the 14th and 16th solar cycle. The periodicities obtained are interpreted as the combined eftects of solar activity, planetary resonances and internal jovian mechanisms. 相似文献
12.
The purpose of the present communication is to identify the short-term (few tens of months) periodicities of several solar indices (sunspot number, Caii area and K index, Lyman , 2800 MHz radio emission, coronal green-line index, solar magnetic field). The procedure used was: from the 3-month running means (3m) the 37-month running means (37m) were subtracted, and the factor (3m – 37m) was examined for several parameters. For solar indices, considerable fluctuations were seen during the ± 4 years around sunspot maxima of cycles 18–23, and virtually no fluctuations were seen in the ± 2 years around sunspot minima. The spacings between successive peaks were irregular but common for various solar indices. Assuming that there are stationary periodicities, a spectral analysis was carried out which indicated periodicities of months: 5.1–5.7, 6.2–7.0, 7.6–7.9, 8.9–9.6, 10.4–12.0, 12.8–13.4, 14.5–17.5, 22–25, 28 (QBO), 31–36 (QBO), 41–47 (QTO). The periodicities of 1.3 year (15.6 months) and 1.7 years (20.4 months) often mentioned in the literature were seen neither often nor prominently. Other periodicities occurred more often and more prominently. For the open magnetic flux estimated by Wang, Lean, and Sheeley (2000) and Wang and Sheeley (2002), it was noticed that the variations were radically different at different solar latitudes. The open flux for < 45 solar latitudes had variations very similar (parallel) to the sunspot cycle, while open flux for > 45 solar latitudes had variations anti-parallel to the sunspot cycle. The open fluxes, interplanetary magnetic field and cosmic rays, all showed periodicities similar to those of solar indices. Many peaks (but not all) matched, indicating that the open flux for < 45 solar latitudes was at least partially an adequate carrier of the solar characteristics to the interplanetary space and thence for galactic cosmic ray modulation. 相似文献
13.
Bao Yang Achim Bruning Jingjing Liu Mary E. Davis Shao Yajun 《Global and Planetary Change》2009,69(1-2):71-78
The climatological signal of δ18O variations preserved in ice cores recovered from Puruogangri ice field in the central Tibetan Plateau (TP) was calibrated with regional meteorological data for the past 50 years. For the period AD 1860–2000, 5-yearly averaged ice core δ18O and a summer temperature reconstruction derived from pollen data from the same ice core were compared. The statistical results provide compelling evidence that Puruogangri ice core δ18O variations represent summer temperature changes for the central TP, and hence regional temperature history during the past 600 years was revealed. A comparison of Puruogangri ice core δ18О with several other temperature reconstructions shows that broad-scale climate anomalies since the Little Ice Age occurred synchronously across the eastern and southern TP, and the Himalayas. Common cold periods were identified in the 15th century, 1625–1645 AD, 1660–1700 AD, 1725–1775 AD, 1795–1830 AD, 1850–1870 AD, 1890–1920 AD, 1940–1950 AD, and 1975–1985 AD. The period 1725–1775 AD was one of the most prolonged cool periods during the past 400 years and corresponded to maximum Little Ice Age glacier advance of monsoonal temperate glaciers of the TP. 相似文献
14.
This study deals with the short-term variations of cosmic ray intensity during the interval 1973–78. Daily means of high latitude neutron and meson monitors from the same station and those of a low latitude neutron monitor have been analysed using the Chree method of superposed epochs. The zero epoch for the Chree analyses corresponds to the day of a substantial increase (V 200 km s–1) in the solar wind speed to values of 550 km s–1 and which persists at such high values for an interval of at least three days. The investigation reveals the existence of two types of cosmic ray intensity variations with distinctly different spectral characteristics. During the interval 1973–76, relative changes in the neutron and meson monitor rates are nearly equal indicating an almost flat rigidity spectrum of variation. During 1977–78, however, the spectrum acquires a negative spectral character similar to that observed for Forbush decreases. We suggest that events of the interval 1973–76 are essentially due to high speed streams associated with solar coronal holes and that events of the interval 1977–78 are due to fast streams from solar active regions with flare activity. 相似文献
15.
Power spectral analysis of cosmic-ray intensity recorded by eight stations was carried out over a wide range of frequencies from 2.3 × 10–8 Hz to 5.8 × 10–6 Hz (2–500 days) during the period 1964–1995. Spectrum results of large-scale fluctuations have revealed the existence of a broad peak near 250–285 days and a narrower peak at 45–50 days during the studied epochs as a stable feature in all neutron monitors covering a wide rigidity range. The cosmic-ray power spectrum displayed significant peaks of varying amplitude with the solar rotation period (changed inversely with the particle rigidities) and its harmonics. The amplitudes of 27-day and 13.5-day fluctuations are greater during the positive-polarity epochs of the interplanetary magnetic field (qA>0) than during the qA<0 epochs. The comparison of cosmic-ray power spectra during the four successive solar activity minima have indicated that at the low-rigidity particles the spectrum differences between the qA>0 and qA<0 epochs are significantly large. Furthermore, the spectrum for even solar maximum years are higher and much harder than the odd years. There are significant differences in the individual spectra of solar maxima for different cycles. 相似文献
16.
The primary scientific objectives of the Hard X-Ray Burst Spectrometer (HXRBS) to be flown on the Solar Maximum Mission are as follows: (1) To determine the nature of the mechanisms which accelerate electrons to 20–100 keV in the first stage of a solar flare and to > 1 MeV in the second stage of many flares; and (2) to characterize the spatial and temporal relation between electron acceleration, storage and energy loss throughout a solar flare.Measurements of the spectrum of solar X-rays will be made in the energy range from 20 to 260 keV using an actively-shielded CsI(Na) scintillator with a thickness of 0.635 cm and a sensitive area of 71 cm2. Continuous measurements with a time resolution of 0.128 s will be made of the 15-channel energy-loss spectrum of events in this scintillator in anticoincidence with events in the CsI(Na) shield. Counting-rate data with a time resolution as short as 1 ms will also be available from a limited period each orbit using a 32K-word circulating memory triggered by a high event rate.In the first year after launch, it is expected that approximately 1000 flares will be observed above the instrument sensitivity threshold, which corresponds to a 20–200 keV X-ray flux of 2 × 10–1 photons (cm2 s)–1 lasting for at least one second. 相似文献
17.
P. A. Sturrock 《Solar physics》2009,254(2):227-239
A search for any particular feature in any single solar neutrino dataset is unlikely to establish variability of the solar
neutrino flux since the count rates are very low. It helps to combine datasets, and in this article we examine data from both
the Homestake and GALLEX experiments. These show evidence of modulation with a frequency of 11.85 year−1, which could be indicative of rotational modulation originating in the solar core. We find that precisely the same frequency
is prominent in power spectrum analyses of the ACRIM irradiance data for both the Homestake and GALLEX time intervals. These
results suggest that the solar core is inhomogeneous and rotates with a sidereal frequency of 12.85 year−1. From Monte Carlo calculations, it is found that the probability that the neutrino data would by chance match the irradiance
data in this way is only 2 parts in 10 000. This rotation rate is significantly lower than that of the inner radiative zone
(13.97 year−1) as recently inferred from analysis of Super-Kamiokande data, suggesting that there may be a second, inner tachocline separating
the core from the radiative zone. This opens up the possibility that there may be an inner dynamo that could produce a strong
internal magnetic field and a second solar cycle. 相似文献
18.
H.J. Haubold 《Astrophysics and Space Science》1997,258(1-2):201-218
Wavelet analysis offers an alternative to Fourier based time- series analysis and is particularly useful when spectral features
are time dependent. We analyze the solar neutrino capture rate of the radiochemical Homestake chlorine experiment with abbreviated
Morlet wavelets, using Foster's (AJ, 111,1709(1996)) rescaled wavelet technique. We emphasize the complementarity of wavelet
analysis to Fourier analysis. Wavelet analysis confirms the results of previously undertaken Fourier analysis. The Homestake
data seem to contain a harmonic content with periodicities of 4.76 yr, 1.89 yr, 0.85 yr, and 0.51 yr. Wavelet analysis reveals
that the 4.76 yr and 1.89 yr periods show an almost constant behavior over the 25 yr Homestake data record, while the 0.85
yr and 0.51 yr periods exhibit a transient phenomenon. The analysis does not show strong evidence for a period of the solar
11 yr cycle.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
19.
This article presents a comparative analysis of solar activity data, Mt Wilson diameter data, Super-Kamiokande solar neutrino data, and nuclear decay data acquired at the Lomonosov Moscow State University (LMSU). We propose that salient periodicities in all of these datasets may be attributed to r-mode oscillations. Periodicities in the solar activity data and in Super-Kamiokande solar neutrino data may be attributed to r-mode oscillations in the known tachocline, with normalized radius in the range 0.66–0.74, where the sidereal rotation rate is in the range 13.7–14.6 year−1. We propose that periodicities in the Mt Wilson and LMSU data may be attributed to similar r-mode oscillations where the sidereal rotation rate is approximately 12.0 year−1, which we attribute to a hypothetical “inner” tachocline separating a slowly rotating core from the radiative zone. We also discuss the possible role of the Resonant Spin Flavor Precession (RSFP) process, which leads to estimates of the neutrino magnetic moment and of the magnetic field strength in or near the solar core. 相似文献
20.
The observed capture rate for solar neutrinos in the 37Cl detector is lower than the predicted capture rate. This discrepancy between theory and observation is known as the ‘solar neutrino problem’. I review the basic elements in this problem: the detector efficiency, the theory of stellar (solar) evolution, the nuclear physics of energy generation, and the uncertainties in the predictions. I also answer the questions of: So What? and What Next?
相似文献