共查询到20条相似文献，搜索用时 31 毫秒
1.
G. Feulner 《Solar physics》2013,282(2):615-627
The Mauna Loa Observatory record of direct-beam solar irradiance measurements for the years 1958?–?2010 is analysed to investigate the variation of clear-sky terrestrial insolation with solar activity over more than four solar cycles. The raw irradiance data exhibit a marked seasonal cycle, extended periods of lower irradiance due to emissions of volcanic aerosols, and a long-term decrease in atmospheric transmission independent of solar activity. After correcting for these effects, it is found that clear-sky terrestrial irradiance typically varies by ≈?0.2±0.1 % over the course of the solar cycle, a change of the same order of magnitude as the variations of the total solar irradiance above the atmosphere. An investigation of changes in the clear-sky atmospheric transmission fails to find a significant trend with sunspot number. Hence there is no evidence for a yet unknown effect amplifying variations of clear-sky irradiance with solar activity. 相似文献
2.
Gerald M. Keating 《Solar physics》1981,74(2):321-347
Observational evidence and theoretical predictions of the response of ozone to solar variations are reviewed. Short-term solar proton effects, possible effects of galactic cosmic rays modulated by the Sun, and the effects of 27-day solar rotation and 11-year solar cycle variations are discussed. Solar proton effects on HO
x
chemistry in the mesosphere and NO
x
chemistry in the stratosphere with resulting catalytic destruction of O3 help validate present day photochemical models. If there is an 11-year solar cycle variation in global ozone, the large dynamical effects at individual locations and the lack of good global coverage of ground based and in situ measurements can disguise it. Recently, with the global coverage of satellites, it has become possible to accurately determine global mean ozone. It has been found that variations in global mean ozone filtered for seasonal variations are highly correlated with variations of the 10.7 cm solar activity index and that global mean ozone responds rapidly to solar activity index variations. Photochemical models indicate that the observed 3% variations in global mean ozone over the solar cycle can be accounted for by solar UV variations which are not inconsistent with recent solar measurements.Proceedings of the 14th ESLAB Symposium on Physics of Solar Variations, 16–19 September 1980, Scheveningen, The Netherlands. 相似文献
3.
We have used data from five neutron monitor stations with primary rigidity (Rm) ranging from 16 GeV to 33 GeV to study the diurnal variations of cosmic rays over the period: 1965–1986 covering one 22-year solar magnetic cycle. The heliosphere interplanetary magnetic field (IMF) and plasma hourly measurements taken near Earth orbit, by a variety of spacecraft, are also used to compare with the results of solar diurnal variation. The local time of maximum of solar diurnal diurnal variations displays a 22-year cycle due to the solar polar magnetic field polarities. In general, the annual mean of solar diurnal amplitudes, magnitude of IMF and plasma parameters are found to show separte solar cycle variations. Moreover, during the declining period of the twenty and twenty-ne solar cycles, large solar diurnal amplitudes are observed which associated with high values of solar wind speed, plasma temperature and interplanetary magnetic field magnitude B3. 相似文献
4.
The rate of production of NO in the thermosphere is expected to vary greatly over the course of an 11-year solar cycle because the fluxes of both extreme ultraviolet radiation and auroral particles are known to increase substantially from solar minimum to solar maximum. In the stratosphere, NO participates in a catalytic cycle which constitutes the dominant photochemical destruction mechanism for stratospheric ozone. If appreciable long range transport of NO from the thermosphere to the upper stratosphere occurs, its effects should therefore be manifested in upper atmospheric ozone density variations over the 11-year solar cycle. In this paper, model predictions of the seasonal and latitudinal variations in upper stratospheric O3 associated with NO transport for different levels of solar activity are compared to satellite observations of upper stratospheric ozone abundances. 相似文献
5.
Using the GONG data for a period over four years, we have studied the variation of frequencies and splitting coefficients
with solar cycle. Frequencies and even-order coefficients are found to change significantly with rising phase of the solar
cycle. We also find temporal variations in the rotation rate near the solar surface. 相似文献
6.
Usoskin I. G. Kovaltsov G. A. Kananen H. Mursula K. Tanskanen P. J. 《Solar physics》1997,170(2):447-452
Cycles of phase evolution of solar activity and cosmic-ray variations are reconstructed by means of the delay component method, which allows us to study the temporal behaviour of time lag between solar activity and cosmic-ray cycle phases. It is shown that the period of the late 20th cycle was very unusual. We have found a delay in the phase of the solar activity cycle with respect to that of cosmic rays and discuss the heliospheric conditions responsible for this delay. 相似文献
7.
Gerhard Schmidtke 《Solar physics》1981,74(1):251-263
The solar irradiance below 120 nm was first predicted by astronomers. Since its accurate measurement required the solution of a variety of technological problems, little is known about the variability before 1972, though for more than two decades data have been collected. Therefore, on a quantitative basis only a very rough picture can be given for the solar cycle 19. Also, not enough data with sufficient absolute accuracy are available to describe the solar EUV flux variations of the solar cycle 20, especially during the period of solar maximum. However, due to technological improvements of space and laboratory instrumentations, an almost complete set of data has been obtained from 1972 to date. These observations exhibit strong differences of the flux variations from solar cycle 20 to 21. - For the theoretical and for semi-empirical treatments of many aeronomic processes controlled by the solar EUV radiation, its adequate representation e.g. as indices is required. The problems involved and possible solutions are discussed. Results from some relevant aeronomically oriented computations based on variable solar EUV fluxes are presented.Proceedings of the 14th ESLAB Symposium on Physics of Solar Variations, 16–19 September 1980, Scheveningen, The Netherlands. 相似文献
8.
We have investigated long-term variations of solar brightness as a function of both time and solar latitude using eight years
of ground-based photometric data in conjunction with space-based irradiance data. In particular, we have examined whether
the combination of sunspot brightness deficits and facular brightness excesses is sufficient to explain the solar cycle irradiance
variations. After correcting for the contribution from sunspots, we find that the irradiance data can be adequately explained
by a model in which the remaining brightness variations are due entirely to facular contributions confined to the magnetically
active latitudes. Thus we find no support for the hypothesis that there are convectively driven hot bands in the active latitudes,
and our data show brightness variations that are well described by a facular contrast function. 相似文献
9.
C. Varotsos 《Astrophysics and Space Science》1988,146(2):339-345
The response of the stratosphere and lower mesosphere to quasi-eleven-year solar activity cycle (indicated by sunspot variations) is studied by using temperature data obtained from rockets which are mostly based on datasonde system throughout the decade 1969–1978. It is suggested that the solar trace is evident at wintertime in the strato-mesosphere over low and middle latitudes. At summertime in the lower mesosphere over high latitudes the solar trace is absent. During springtime the solar signal appears over low latitudes and diminishes to the middle and high latitudes. The reverse occurs at falltime. The observed stratospheric temperature and ozone variations during the solar activity cycle are possibly within model calculations of UV and solar particle enhancements at solar maximum. 相似文献
10.
As an important measurement parameter, global total electron content (TEC) is appropriate for the study of the Sun–Earth connection.
In this paper, the wavelet technique is employed to investigate the periodicities in global mean TEC during 1995–2008. Analysis
results show several remarkable components (including 27-day, semiannual and annual cycles) existing in global mean TEC with
obvious time-variable characteristics, besides 11-year cycle. After analyzing sunspot numbers and solar extreme ultra-violet
(EUV) radiation variations during this time period, except for semiannual variations, close correlation between global mean
TEC and solar variations is found, especially, a strong resemblance of the 27-day fluctuation exists in global mean TEC, sunspot
and solar EUV radiation variations. 相似文献
11.
L.H. Ma 《New Astronomy》2009,14(1):1-3
Long-term variations of solar activity significantly affect terrestrial phenomena. Studies have shown cyclic components in solar activity and geophysical phenomena (e.g., the Schwabe, Hale, Gleissberg, and Suess cycles, and a cycle of about 2300 years). In this paper, the wavelet technique is employed to investigate the Gleissberg cycle in solar variations during 5000 BC–1995 AD. Analysis shows time-variable characteristics in the Gleissberg solar cycle over the period; no obvious correlation between the Gleissberg and Suess cycles has been found. 相似文献
12.
Pter Kirly 《Journal of Astrophysics and Astronomy》2000,21(3-4):431-437
The heliosphere is the region filled with magnetized plasma of mainly solar origin. It extends from the solar corona to well
beyond the planets, and is separated from the interstellar medium by the heliopause. The latter is embedded in a complex and
still unexplored boundary region. The characteristics of heliospheric plasma, fields, and energetic particles depend on highly
variable internal boundary conditions, and also on quasi-stationary external ones. Both galactic cosmic rays and energetic
particles of solar and heliospheric origin are subject to intensity variations over individual solar cycles and also from
cycle to cycle. Particle propagation is controlled by spatially and temporally varying interplanetary magnetic fields, frozen
into the solar wind. An overview is presented of the main heliospheric components and processes, and also of the relevant
missions and data sets. Particular attention is given to flux variations over the last few solar cycles, and to extrapolated
effects on the terrestrial environment. 相似文献
13.
George L. Withbroe 《Solar physics》2009,257(1):71-81
The daily images and magnetograms acquired by MDI are a rich source of information about the contributions of different types
of solar regions to variations in the total solar irradiance (TSI). These data have been used to determine the temporal variation
of the MDI irradiance, the mean intensity of the solar disk in the continuum at 676.8 nm. The short-term (days to weeks) variations
of the MDI irradiance and TSI are in excellent agreement with rms differences of 0.011%. This indicates that MDI irradiance
is an excellent proxy for short-term variations of TSI from the competing irradiance contributions of regions causing irradiance
increases, such as plages and bright network, and regions causing irradiance decreases, such as sunspots. However, the long-term
or solar cycle variation of the MDI proxy and TSI differ over the 11-year period studied. The results indicate that the primary
sources of the long-term (several months or more) variations in TSI are regions with magnetic fields between about 80 and
600 G. The results also suggest that the difference in the long-term variations of the MDI proxy and TSI is due to a component
of TSI associated with sectors of the solar spectrum where the contrast in intensity between plages and the quiet Sun is enhanced
(e.g., the UV) compared to the MDI proxy. This is evidence that the long-term variation of TSI is due primarily to solar cycle
variations of the irradiance from these portions of solar spectrum, a finding consistent with modeling calculations indicating
that approximately 60% of the change in TSI between solar minimum and maximum is produced by the UV part of the spectrum shortward
of 400 nm (Solanki and Krivova, Space Sci. Rev. 125, 53, 2006). 相似文献
14.
L. H. Ma 《Solar physics》2007,245(2):411-414
Long-term variations of solar activity closely relate to terrestrial phenomena. More and more people attach importance to
studies of long-term fluctuations of solar variation. However, because direct observations of solar activity are available
only for the past four centuries, such studies are few. In this work, using the wavelet technique, the author investigates
long-term fluctuations of reconstructed sunspot number series covering the past 11 400 years, with emphasis on the thousand-year
cycle signals of solar variation. The results show a thousand-year cycle in solar activity. 相似文献
15.
The monthly cosmic ray intensity (CRI) time series from Climax, Huancayo, Moscow, Kiel, and Calgary are used to investigate
the presence of the 11-year periodic component with special attention paid to the solar influence on these variations. The
results show obvious 11-year temporal characteristics in CRI variations. We also find a close anticorrelation between the
11-year solar cycle and CRI variations and time delays of the CRI relative to solar activity. 相似文献
16.
D. P. Gregg 《Solar physics》1984,90(1):185-194
This paper describes a novel non-linear oscillator model of the sunspot cycle which accurately reproduces several of the observed qualitative and quantitative characteristics of the real cycle including the long term amplitude modulation pattern. The model accounts for 96% of cycle peak height variance over the period 1859 to 1980. The aim of this work is to assess the potential of such models for forecasting solar activity on decadal and possibly longer time scales. Longer term forecasts may have practical economic significance because of the growing evidence for relationships between solar cycle variations and terrestrial weather and climatic variations (Bandeen and Moran, 1975; Currie, 1980; Williams, 1981). The model predicts that cycle 22 will have an annual mean peak amplitude in the range 25 to 45, the lowest peak activity for 260 yr. 相似文献
17.
The solar soft X-ray (XUV) radiation is important for upper atmosphere studies as it is one of the primary energy inputs and
is highly variable. The XUV Photometer System (XPS) aboard the Solar Radiation and Climate Experiment (SORCE) has been measuring
the solar XUV irradiance since March 2003 with a time cadence of 10 s and with about 70% duty cycle. The XPS measurements
are between 0.1 and 34 nm and additionally the bright hydrogen emission at 121.6 nm. The XUV radiation varies by a factor
of ∼2 with a period of ∼27 days that is due to the modulation of the active regions on the rotating Sun. The SORCE mission
has observed over 20 solar rotations during the declining phase of solar cycle 23. The solar XUV irradiance also varies by
more than a factor of 10 during the large X-class flares observed during the May–June 2003, October–November 2003, and July
2004 solar storm periods. There were 7 large X-class flares during the May–June 2003 storm period, 11 X-class flares during
the October–November 2003 storm period, and 6 X-class flares during the July 2004 storm period. The X28 flare on 4 November
2003 is the largest flare since GOES began its solar X-ray measurements in 1976. The XUV variations during the X-class flares
are as large as the expected solar cycle variations. 相似文献
18.
Observations of short-term irradiance variations and consideration of mechanisms of the solar activity cycle suggest the possibility of long-term variation of the solar flux. Since the limb darkening is sensitive to effective temperature and convective efficiency, observations of the solar limb darkening may provide a useful means to detect and study long-term global variations. The limb-darkening responses to impulsive variation (in depth) of the source function, to effective temperature variation, and to convection variations are presented. For the variations considered, the limb-darkening variation is approximately linearly proportional to the associated parameters. The minimum detectable amplitude of those parametric variations is derived as a function of observational noise. Given our demonstrated errors of observation, single-parameter sensitivies are 3 K for effective temperature variation and 0.007 for local mixing-length variation for year to year changes at 99% confidence. 相似文献
19.
T. W. Cole 《Solar physics》1973,30(1):103-110
The techniques of power spectral analysis are used to determine significant periodicities in the annual mean relative sunspot numbers. The main conclusion is that a period of 10.45 yr is very basic and can be associated with an excitation of new solar cycles. When combined with a period of 11.8 yr, associated here with the free-running length of a solar cycle, the mean cycle length of 11.06 yr and a phase variation of 190 yr are explained. Similarly the amplitude variations with periods 88 and 59 yr (previously described as the 80-yr cycle) are due to an amplitude modulation of the solar cycle by a period of 11.9±0.3 yr. The results dispute several associations of planetary position and solar activity.Radiophysics Publication RPP 1647, January, 1973. 相似文献
20.
Ilya Yu Alekseev 《Solar physics》2004,224(1-2):187-194
We present the first results of searching for stellar cycles by analysis of stellar spottedness using an algorithm developed
at the Crimean Astrophysical Observatory. For more than 35 red spotted stars, we find ten targets which demonstrate cyclic
variations of average latitudes and total areas of starspots. Activity cycles detected by this method have a typical cycle
length about 4–15 years which are analogous to the 11-year solar Schwabe cycle. Most of the program stars demonstrate a rough
analogue with the solar butterfly diagram. They show a tendency for the average starspot latitude lowering when the total
spot area grows. At the same time these stars show variations of stellar photometric period (which is traced by starspots)
with the starspot latitudinal drift analogously to the solar differential rotation effect. We suspect that the starspot latitudinal
drift rate and the differential rotation gradient depend on the stellar spectral type. 相似文献