共查询到20条相似文献，搜索用时 31 毫秒
1.
Rolando R. Garcia Susan Solomon Raymond G. Roble David W. Rusch 《Planetary and Space Science》1984,32(4):411-423
A two-dimensional numerical model with coupled photochemistry and dynamics has been used to investigate the response of the middle atmosphere (16–116 km) to changes in solar activity over the 11-year solar cycle. Model inputs that vary with solar cycle include solar radiation, cosmic ray and auroral ionization rates and the flux of NOx at the model's upper boundary.In this study, the results of model runs for solar cycle minimum and maximum conditions are compared. In the stratosphere, using currently accepted estimates of changes in solar radiation at wavelengths longer than 180 nm, only small responses in ozone, temperature and zonal winds are obtained. On the other hand, changes at shorter wavelengths, and the effects of particle precipitation, lead to large variations in the abundances of trace species in the thermosphere and upper mesosphere. In particular, very large abundances of NOx are produced above 90 km by auroral particle precipitation. Considerable amounts of NOx are transported subsequently to the stratosphere by the global mean meridional circulation. It is shown that this excess NOx can lead to significant decreases in ozone concentrations at high latitudes and that it may explain observations of nitrate deposition in Antarctic snow. 相似文献
2.
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
3.
J. R. Bates 《Solar physics》1981,74(2):399-415
Variations in solar UV radiation can lead to changes in the mean temperature and wind distributions in the stratosphere and, through modification of the ozone photochemistry, to changes in the damping rate of temperature perturbations about the mean. Such changes can influence the stratospheric propagation characteristics of planetary waves generated in the troposphere, leading to changes in the steady state interference pattern of these waves at all levels. In particular, the poleward heat transfer by the planetary waves in the troposphere can be strongly modified, thus providing a mechanism whereby solar cycle variations in ultraviolet radiation can influence climate.The dynamics of the mechanism are presented in a simple form and the literature on the subject is reviewed.Proceedings of the 14th ESLAB Symposium on Physics of Solar Variations, 16–19 September 1980, Scheveningen, The Netherlands. 相似文献
4.
Paul C. Simon 《Solar physics》1981,74(1):273-291
The solar ultraviolet irradiance measurements in the 120–400 nm wavelength range are reviewed and compared showing still important discrepancies between the irradiance values deduced from the most recent observations.The possible variations of the solar ultraviolet irradiances with the 27-day rotation period of the Sun and with the 11-year activity cycle are presented and discussed on the basis of the available irradiation fluxes obtained during the rising phase of solar cycle 21.The spectral features of both kinds of variation are clearly related to the solar atmospheric layer from which the corresponding radiation is emitted.Proceedings of the 14th ESLAB Symposium on Physics of Solar Variations, 16–19 September 1980, Scheveningen, The Netherlands. 相似文献
5.
The geomagnetic activity is the result of the solar wind–magnetosphere interaction. It varies following the basic 11-year solar cycle; yet shorter time-scale variations appear intermittently. We study the quasi-periodic behavior of the characteristics of solar wind (speed, temperature, pressure, density) and the interplanetary magnetic field (B x , B y , B z , β, Alfvén Mach number) and the variations of the geomagnetic activity indices (D ST, AE, A p and K p). In the analysis of the corresponding 14 time series, which span four solar cycles (1966?–?2010), we use both a wavelet expansion and the Lomb/Scargle periodograms. Our results verify intermittent periodicities in our time-series data, which correspond to already known solar activity variations on timescales shorter than the sunspot cycle; some of these are shared between the solar wind parameters and geomagnetic indices. 相似文献
6.
Solar wind isotropic proton temperatures as measured out to 12.2 AU heliocentric distance by the Ames plasma analyzer aboard Pioneer-10 are presented as consecutive averages over three Carrington solar rotations and discussed. The weighted least-squares fit of average temperature to heliocentric radial distance, R, yields the power law R
-0.52. These average proton temperatures are not correlated as well with Pioneer-10's heliocentric radial distance (-0.85) as are the corresponding average Zürich sunspot numbers R
z (-0.95). Consequently, it is difficult to isolate the spatial gradient in the Pioneer-10 solar wind proton temperatures using that data alone. 相似文献
7.
In this work, the evolution of the relationship between Solar Cycle Length of solar cycle n (SCL
n
) and Solar Cycle Amplitude of the solar cycle n+1 (SCA
n+1) is studied by using the R
Z and R
G sunspot numbers. We conclude that this relationship is only strongly significant in a statistical sense during the first
half of the historical record of R
Z sunspot number whereas it is considerably less significant for the R
G sunspot number. In this sense we assert that these simple lagged relationships should be avoided as a valid method to predict
the following solar activity amplitude. 相似文献
8.
Comet outburst activity and the structure of solar wind streams were compared on the basis of Pioneer 10, 11, Vela 3 and IMP
7, 8 measurements at the heliocentric distance r ≈ 1–6 AU. It is shown that the solar wind velocity waves which are evolving into corotating shock waves beyond the Earth
orbit may be responsible for comet outburst activity. The correlation between variations of comet outburst activity with heliocentric
distance and the behavior of the solar wind velocity waves is established. The closeness of the characteristic times for the
velocity waves and comet outburst activity (7–8 days at r = 1 AU) as well as the simultaneous growth of both the characteristic times with r are noted. The observed distribution of the comet outburst activity parameters during the 11-year cycle is also in good agreement
with the phase distributions during the 11-year cycle of variations of the coronal hole areas and the rate of change of the
sunspot area δS
p. 相似文献
9.
Ilias M. Vardavas 《Solar physics》1987,108(2):403-410
A radiative-convective climate model was used to explore the response of the mean global vertical temperature structure to a variation in the solar UV flux over the solar cycle. The model predicted a cooling of the troposphere and a warming of the stratosphere from solar minimum to solar maximum. The response of the atmospheric temperature to solar UV variations was found to be moderated by a concomitant change in the mean global stratospheric ozone content. 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.
We report observations of the large-scale spatial dependence of the Sun's luminosity variations over the period 1993–1995. The measurements were made using a new scanning disk solar photometer at Big Bear Solar Observatory, specially designed to measure large-scale brightness variations at the 10–4 level. Since the level of solar activity was very low for the entire observation period, the data show little solar cycle variation. However, the residual brightness signal I/I (after subtracting the mean, first, and second harmonics) does show a strong dependence on heliocentric angle, peaking near the limb. This is as one would expect if the residual brightness signal (including the excess brightness coming from the active latitudes) were primarily facular in origin. Additional data over the next few years, covering the period from solar minimum to maximum, should unambiguously reveal the large-scale spatial structure of the solar cycle luminosity variations. 相似文献
12.
A. V. Mordvinov 《Solar physics》2007,246(2):445-456
A comparative analysis of solar and heliospheric magnetic fields in terms of their cumulative sums reveals cyclic and long-term
changes that appear as a magnetic flux imbalance and alternations of dominant magnetic polarities. The global magnetic flux
imbalance of the Sun manifests itself in the solar mean magnetic field (SMMF) signal. The north – south asymmetry of solar
activity and the quadrupole mode of the solar magnetic field contribute the most to the observed magnetic flux imbalance.
The polarity asymmetry exhibits the Hale magnetic cycle in both the radial and azimuthal components of the interplanetary
magnetic field (IMF). Analysis of the cumulative sums of the IMF components clearly reveals cyclic changes in the IMF geometry.
The accumulated deviations in the IMF spiral angle from its nominal value also demonstrate long-term changes resulting from
a slow increase of the solar wind speed over 1965 – 2006. A predominance of the positive IMF B
z
with a significant linear trend in its cumulative signal is interpreted as a manifestation of the relic magnetic field of
the Sun. Long-term changes in the IMF B
z
are revealed. They demonstrate decadal changes owing to the 11/22-year solar cycle. Long-duration time intervals with a dominant
negative B
z
component were found in temporal patterns of the cumulative sum of the IMF B
z
. 相似文献
13.
Two sets of nitrate (NO3
–) concentration data in Central Greenland ice, obtained through the GISP2 collaboration and by the University of Kansas, were analyzed statistically. The two records correlate well over time scales from a few years up to a century. They both contain quasi five-year, decadal and century-type time variations. A quasi five-year periodicity resulting from increases in the mean nitrate concentration before and after maximum sunspot number was confirmed. A tendency of solar proton events to occur more frequently during the rise/decline phases of the solar cycle may cause a quasi five-year variation. Century-type (60–110 yr) variability in nitrate outstrips the corresponding Gleissberg cycle in sunspots by 12–17 years and changes synchronously (correlates with zero phase shift) with the smoothed length of the solar Schwabe cycle. A significant correlation between century-type periodicities for nitrates in Greenland ice and northern Fennoscandian temperatures was established. The results show that despite a strong dependence on local meteorology, nitrate concentration in ice contains valuable information about global geophysical phenomena in the past. 相似文献
14.
Additional analysis of the behavior of the international sunspot number (R) series and the solar radio flux density (F10.7 cm) series during two long (250–500 days) and distinct episodes of persistent ≈13-day variations (Crane, Solar Phys. 1998, 253, 177) is reported. The conclusion is that while the center-to-limb behavior of R does not change between solar minimum and solar maximum, F10.7 cm exhibits significantly less limb brightening at solar maximum than at solar minimum. 相似文献
15.
V. A. Alexeev 《Solar System Research》2007,41(6):527-534
The global warming on Earth during the last century has been discussed in many studies. The most significant factors of climate change are the increase in the atmospheric concentration of greenhouse gases, catastrophic eruptions of volcanoes, and variations in the solar activity. In this paper, we consider the character of climate change and its possible relation to solar-activity variations using the data of the global network of meteorological stations on temperature variations in different regions across the globe from 1880 and information about variations in the relative sunspot number over the last 300 years and temporal variations in the total solar irradiation. We found that the annual mean sunspot number increased on average by about 0.2% per year in both 11-year and secular cycles. The increase in the globally averaged surface air temperature in the period 1880–2004 was Δt = 0.61 ± 0.04 °C. The difference in Δt calculated for periods with different solar-activity levels in 11-year cycles was estimated. This difference was most clearly revealed over land at high latitudes of the northern hemisphere. The medians of the distributions of the annual mean surface air temperature over land, ocean, and over the entire globe in years with high solar activity in the secular cycle are significantly greater than the corresponding values related to the years of low solar activity. Noticeable falls in temperature (by ～0.1–0.2°C) through ～1900–1920 and 1945–1980 are likely to be associated with the radiation balance perturbation caused by a large number of catastrophic volcanic eruptions during these periods. A considerable warming during the last three decades is most probably due to the substantial growth in the rate of carbon dioxide input to the atmosphere and the corresponding large increase in its concentration. The importance of this factor of global warming becomes even greater if we bear in mind that the solar activity in the secular cycle declines after 1970. 相似文献
16.
The purpose of the present study is to develop an empirical model based on precursors in the preceding solar cycle that can
be used to forecast the peak sunspot number and ascent time of the next solar cycle. Statistical parameters are derived for
each solar cycle using “Monthly” and “Monthly smoothed” (SSN) data of international sunspot number (R
i). Primarily the variability in monthly sunspot number during different phases of the solar cycle is considered along with
other statistical parameters that are computed using solar cycle characteristics, like ascent time, peak sunspot number and
the length of the solar cycle. Using these statistical parameters, two mathematical formulae are developed to compute the
quantities [Q
C]
n
and [L]
n
for each nth solar cycle. It is found that the peak sunspot number and ascent time of the n+1th solar cycle correlates well with the parameters [Q
C]
n
and [L]
n
/[S
Max]
n+1 and gives a correlation coefficient of 0.97 and 0.92, respectively. Empirical relations are obtained using least square fitting,
which relates [S
Max]
n+1 with [Q
C]
n
and [T
a]
n+1 with [L]
n
/[S
Max]
n+1. These relations predict a peak of 74±10 in monthly smoothed sunspot number and an ascent time of 4.9±0.4 years for Solar
Cycle 24, when November 2008 is considered as the start time for this cycle. Three different methods, which are commonly used
to define solar cycle characteristics are used and mathematical relations developed for forecasting peak sunspot number and
ascent time of the upcoming solar cycle, are examined separately. 相似文献
17.
M. Suzuki 《Solar physics》2014,289(11):4021-4029
Long-term modulation of solar differential rotation was studied with data from Mt. Wilson and our original observations during Solar Cycles 16 through 23. The results are that i) the global B-value (i.e. latitudinal gradient of differential rotation) is modulated with a period of about six or seven solar cycles, ii) the B-values of the northern and southern hemispheres are also modulated with a period similar to the global one, but iii) they show quasi-oscillatory behavior with a phase shift between them. We examined the yearly fluctuations of the B-values in every solar cycle with reference to the phase of the sunspot cycle and found that the B-values in the sunspot-minimum years show large and erratic variations, while those in the sunspot-maximum years show small fluctuations. Positive correlation between the former B-values and the latter was found. We discuss the independent long-term behavior of solar differential rotation between the northern and southern solar hemispheres and the implication for the solar dynamo. 相似文献
18.
Lucien Bossy 《Planetary and Space Science》1983,31(9):977-985
Solar radio fluxes, Zurich relative sunspot number Rz, and Solar Call plage indexes daily values for the period 1957–1980 are analyzed in order to test the stability of the series with respect to time and solar activity. It is found that between the series of the 3,8 and 10 cm radio fluxes and the series of Rz no significant trend with time, solar activity or solar cycle exists when mean values for periods of the order of one year are considered.Then, the daily solar u.v.-irradiances measured since 1969 for H-Lyman-alpha and-beta, the Hel-resonance line and HeII-Lyman-alpha are compared with the 10.7 cm radio fluxes and adjusted. After adjustment, the behaviour of the four series of irradiances with respect to the 10.7 cm flux shows a similar structure as the behaviour typical for the series of the 3 cm or the 8 cm fluxes.This adjustment allows the determination of the slope of the mean variation of the u.v.-irradiances with solar activity. The increases from solar minimum to solar maximum related to the minimum values are respectively : 60% for H-Lyman-alpha, 80% for H-Lyman-beta and 90% for Hel and Hell. 相似文献
19.
This paper investigates a series of daily solar indices: the sunspot number W (1900–2008), solar flux at 2800 MHz F
10.7 (1947–2008), and a number of X-ray flares N
x
(1981–2008). The methods of Fourier and wavelet analysis are used to reveal the so-called 156-day Rieger-type periodicity
(RTP). The W index is observed to have a statistically significant RTP amplitude in the neighborhood of the solar maxima in most of the
solar cycles under study, except for cycles 14, 15, and 23. The 156-day peak is observed to have its largest power during
the declining phase of cycle 16, at the maximum of cycle 21, and during the increasing phase of cycles 20 and 23. Statistically
significant RTPs are also observed at the minima of cycles 17, 18 and 19. We conclude that there is no stable dependence between
RTP and the solar cycle. The wavelet analysis shows that the pattern of the RTP time dependence for the F
10.7 index is almost identical to that of the W index. The correlation coefficient between the RTP curves is 0.95. The correlation coefficients for the pairs of indices
W-N
x
and F
10.7-N
x
are 0.36 and 0.32, respectively. No time lags are found between the RTP starting points for different indices. Thus, the
156-day quasi-periodicity involves, almost simultaneously, events that occur in active regions of the solar atmosphere at
different heights. This paper discusses the possible nature of RTP. 相似文献
20.
Measurements of maximum magnetic flux, minimum intensity, and size are presented for 12 967 sunspot umbrae detected on the
National Aeronautics and Space Administration/National Solar Observatory (NASA/NSO) spectromagnetograms between 1993 and 2004
to study umbral structure and strength during the solar cycle. The umbrae are selected using an automated thresholding technique.
Measured umbral intensities are first corrected for center-to-limb intensity dependence. Log-normal fits to the observed size
distribution confirm that the size-spectrum shape does not vary with time. The intensity – magnetic-flux relationship is found
to be steady over the solar cycle. The dependence of umbral size on the magnetic flux and minimum intensity are also independent
of the cycle phase and give linear and quadratic relations, respectively. While the large sample size does show a low-amplitude
oscillation in the mean minimum intensity and maximum magnetic flux correlated with the solar cycle, this can be explained
in terms of variations in the mean umbral size. These size variations, however, are small and do not substantiate a meaningful
change in the size spectrum of the umbrae generated by the Sun. Thus, in contrast to previous reports, the observations suggest
the equilibrium structure, as manifested by the invariant size-magnetic field relationship, as well as the mean size (i.e., strength) of sunspot umbrae do not significantly depend on the solar-cycle phase. 相似文献