共查询到20条相似文献，搜索用时 234 毫秒
1.
K. F. Tapping D. Boteler P. Charbonneau A. Crouch A. Manson H. Paquette 《Solar physics》2007,246(2):309-326
We develop a model for estimating solar total irradiance since 1600 AD using the sunspot number record as input, since this
is the only intrinsic record of solar activity extending back far enough in time. Sunspot number is strongly correlated, albeit
nonlinearly with the 10.7-cm radio flux (F
10.7), which forms a continuous record back to 1947. This enables the nonlinear relationship to be estimated with usable accuracy
and shows that relationship to be consistent over multiple solar activity cycles. From the sunspot number record we estimate
F
10.7 values back to 1600 AD. F
10.7 is linearly correlated with the total amount of magnetic flux in active regions, and we use it as input to a simple cascade
model for the other magnetic flux components. The irradiance record is estimated by using these magnetic flux components plus
a very rudimentary model for the modulation of energy flow to the photosphere by the subphotospheric magnetic flux reservoir
feeding the photospheric magnetic structures. Including a Monte Carlo analysis of the consequences of measurement and fitting
errors, the model indicates the mean irradiance during the Maunder Minimum was about 1 ± 0.4 W m−2 lower than the mean irradiance over the last solar activity cycle. 相似文献
2.
The significant periods of total solar irradiance are 35 d and 26 d in the 23rd and 24th solar activity cycles, respectively. It is inferred that the solar quasi-rotation periods are also 35 d and 26 d in the 23rd and 24th solar activity cycles, respectively. The value of total solar irradiance around the 24th solar activity minimum may be close to the value of Maunder minimum. On the timescales from one solar rotation period to several months, sunspots are the main reason to cause the variation of total solar irradiance, but not the unique one, and the variation of total solar irradiance are not correlated with the Mg II index on the timescales from a few days to one solar rotation period. 相似文献
3.
Variations of solar total and spectral irradiance are prime solar quantities purported to have an influence on the Earth’s
climate. Quantitative estimates of irradiance over as long a time as possible are needed to judge their effectiveness in forcing
the climate. In order to do this reliably, first the measured record must be reproduced and a feeling for the physics underlying
the irradiance variations must be developed. With the help of this knowledge combined with the available proxy data, reconstructions
of irradiance in the past, generally since the Maunder minimum, are attempted. Here a brief introduction to some of the irradiance
reconstruction work aiming at irradiance on time scales of days to the solar cycle is given, followed by a brief and incomplete
overview of the longer-term reconstructions. 相似文献
4.
Given the numerous ground-based and space-based experiments producing the database for the Cycle 23??C?24 Minimum epoch from September 2008 to May 2009, we have an extraordinary opportunity to understand its effects throughout the heliosphere. We use solar radiative output in this period to obtain minimum values for three measures of the Sun??s radiative output: the total solar irradiance, the Mg ii index, and the 10.7 cm solar radio flux. The derived values are included in the research summaries as a means to exchange ideas and data for this long minimum in solar activity. 相似文献
5.
14C abundance on the Earth can be modulated by both the solar wind and irradiance components of the solar cycle. The magnetic field component of the solar wind modulates 14C production whereas the irradiance component can result in a change in the exchange rate between the various reservoirs of the carbon biogeochemical cycle. The effects would be nearly synchronous and difficult to separate. The 0.1% amplitude of irradiance variation during the two most recent solar cycles is well known. A 22-yr cycle exists also in the measured global temperature record.We have divided the University of Washington high-precision data on14C in tree rings into three 91-yr intervals: AD 1540–1630, 1630–1720 and 1715–1805, before, during and after the Maunder Minimum. Unfortunately the AD 1540–1630 interval includes part of the Spörer Minimum as well as the intermediate interval of high solar activity. These data were analyzed by the DFT, MEM and MTM methods of spectral time series analysis. The ca. 22-yr cycle is prominent during the Maunder Minimum, whereas the 11-yr cycle is most prominent after the Maunder Minimum but totally suppressed during the Maunder Minimum. The lesser amplitude of the 11-yr cycle before the Maunder Minimum is most probably due to overlap with the Spörer Minimum.Vasiliev and Kocharov VK83 have previously suggested that the 22-yr cycle persists through the Maunder Minimum whereas the 11-yr cycle is suppressed. Our calculations show that irradiance forcing of the carbon cycle during the 11-yr cycle is negligible, so the observed 11-yr cycle in14 C must be the result of production rate changes. The presence of the 22-yr cycle and suppression of the 11-yr cycle during the Maunder Minimum is in accord with a model by Jokipii Jok91. 相似文献
6.
Variations of total solar irradiance, 10.7 cm radio emission, the Hei 10830 Ú equivalent width and the solar magnetic field flux measured for the entire Sun are compared with variations of the energy index of the global solar magnetic field and the index of the effective solar multipole for years 1979–1992. It is shown that photospheric radiation and that generated in the upper chromosphere and corona display different relationships with the global magnetic field of the Sun, and that interaction between the magnetic field and the solar irradiance is much more complicated than the traditional blocking effect. 相似文献
7.
Judit Pap 《Solar physics》1987,109(2):373-386
A strong correlation was found between the dips in the total solar irradiance and the peaks in the active sunspot areas as well as in the 260 MHz coronal radio flux. This connection might indicate that Alfvén-waves, generated during the interaction of the magnetic fields of the active sunspot groups with the convection, are able to transport away part of the missing energy in the solar constant decreases. These waves can heat the solar corona above the sunspot groups. Another part of the missing energy could be re-radiated later, for example during the decay of the active regions. 相似文献
8.
It is well known that magnetic activity on the Sun modulates from one cycle to the next. The most striking occurrence of this is called a grand minimum where magnetic activity all but disappears. The latest grand minimum occurred between the years 1645 and 1715 and is called the Maunder minimum. In this paper magnetic flux transport simulations are used to consider what type of surface magnetic field configurations may be produced both during and after a grand minimum depending on how the grand minimum occurs. It is shown that the surface configurations during and after a grand minimum strongly depend on the phase of the cycle in which the grand minimum starts and whether it lasts for an odd or even number of cycles. If the grand minimum starts around cycle minimum then a significant amount of large-scale magnetic flux may persist on the Sun at high latitudes during the grand minimum. In contrast, if it starts at cycle maximum during the grand minimum it is possible for there to be essentially zero large-scale magnetic flux over the entire surface of the Sun. It is shown that for a single grand minimum event the reversal of the polar fields at the presently observed time in the solar cycle is only reproduced if the event starts at cycle minimum and extends over an even number of cycles. In contrast, if the grand minimum runs for an odd number of cycles it is possible for there to be no reversal of the polar fields or for the reversals to occur at times inconsistent with our present understanding of the solar cycle. Consequences of the assumptions made in the modelling are discussed and the significance of the simulations for direct modelling of events such as the Maunder minimum are considered. 相似文献
9.
What the Sunspot Record Tells Us About Space Climate 总被引：1，自引：0，他引：1
The records concerning the number, sizes, and positions of sunspots provide a direct means of characterizing solar activity
over nearly 400 years. Sunspot numbers are strongly correlated with modern measures of solar activity including: 10.7-cm radio
flux, total irradiance, X-ray flares, sunspot area, the baseline level of geomagnetic activity, and the flux of galactic cosmic
rays. The Group Sunspot Number provides information on 27 sunspot cycles, far more than any of the modern measures of solar
activity, and enough to provide important details about long-term variations in solar activity or “Space Climate.” The sunspot
record shows: 1) sunspot cycles have periods of 131± 14 months with a normal distribution; 2) sunspot cycles are asymmetric
with a fast rise and slow decline; 3) the rise time from minimum to maximum decreases with cycle amplitude; 4) large amplitude
cycles are preceded by short period cycles; 5) large amplitude cycles are preceded by high minima; 6) although the two hemispheres
remain linked in phase, there are significant asymmetries in the activity in each hemisphere; 7) the rate at which the active
latitudes drift toward the equator is anti-correlated with the cycle period; 8) the rate at which the active latitudes drift
toward the equator is positively correlated with the amplitude of the cycle after the next; 9) there has been a significant
secular increase in the amplitudes of the sunspot cycles since the end of the Maunder Minimum (1715); and 10) there is weak
evidence for a quasi-periodic variation in the sunspot cycle amplitudes with a period of about 90 years. These characteristics
indicate that the next solar cycle should have a maximum smoothed sunspot number of about 145 ± 30 in 2010 while the following
cycle should have a maximum of about 70 ± 30 in 2023. 相似文献
10.
We present a reconstruction of the solar spectrum in the near and mid-ultraviolet spectral range during the Maunder Minimum, a period of strongly suppressed magnetic activity spanning the second half of the 17th century. This spectral reconstruction is based on an extension of the Monte Carlo Solar Spectral Irradiance Model (MOCASSIM). The new version of the model, documented in this paper, extends its spectral range down to 150 nm, its temporal range back to 1610, includes a secular modulation of the quiet-Sun emissivity based on a total solar irradiance reconstruction, and uses the Atmospheric Laboratory for Applications and Science-3 (ATLAS-3) spectrum as a reconstruction baseline. The model is validated against the ATLAS-1 spectrum for 29 March 1992, showing a general agreement varying from ～?1 % in the 300?–?400 nm range, up to 3?–?5 % below 200 nm, the largest discrepancies occurring in emission lines formed in the chromosphere and transition region. We also reconstruct ultraviolet spectra for May 2008 and March 2009, spanning the extended phase of low activity separating Cycles 23 and 24. Our results suggest that despite the unusually long temporal extent of this activity minimum, the ultraviolet emission still remained slightly higher than during the Maunder Minimum, due to the lingering presence of decay products from active regions having emerged in the late descending phase of Cycle 23. 相似文献
11.
Yu. A. Nagovitsyn 《Astronomy Letters》2007,33(5):340-345
We have obtained new consistent versions of the 400-yr time series of the Wolf sunspot number W, the sunspot group number G, and the total sunspot area S (or the total sunspot magnetic flux Φ). We show that the 11-yr cycle did not cease during the Maunder minimum of solar activity. The characteristics of the extrema of individual 11-yr cycles in 1600–2005 have been determined in terms of the total sunspot area index. We provide arguments for using alternating (“magnetic”) time series of indices in investigating the solar cyclicity. 相似文献
12.
Hirokazu Yoshimura 《Solar physics》1998,177(1-2):329-342
A time-delay concept is described to play a vital role in a hypothesis of the mechanism of the solar total irradiance variation driven by time variation of the thermal structure of the solar convection zone, with time scales on the order of 10 to 10000 years. The hypothesis is formulated on an empirical basis from an analysis of the observed data of the magnetic field of the Sun and of the global land-air temperature anomalies of the Earth, with the assumption that the land area of the Earth can be a good recorder of the solar total irradiance variation in the past. As a result of the assumption within the context of the present hypothesis, it was found that the solar total irradiance increase and the global warming of the Earth from the early 20th century to the present time could be caused by release of heat stored in the solar convection zone in the Maunder Minimum of the 17th century. 相似文献
13.
Electromagnetic radiation from the Sun is Earths primary energy source. Space-based radiometric measurements in the past two decades have begun to establish the nature, magnitude and origins of its variability. An 11-year cycle with peak-to-peak amplitude of order 0.1 % is now well established in recent total solar irradiance observations, as are larger variations of order 0.2 % associated with the Suns 27-day rotation period. The ultraviolet, visible and infrared spectral regions all participate in these variations, with larger changes at shorter wavelengths. Linkages of solar radiative output variations with solar magnetism are clearly identified. Active regions alter the local radiance, and their wavelength-dependent contrasts relative to the quiet Sun control the relative spectrum of irradiance variability. Solar radiative output also responds to sub-surface convection and to eruptive events on the Sun. On the shortest time scales, total irradiance exhibits five minute fluctuations of amplitude
%, and can increase to as much as 0.015 % during the very largest solar flares. Unknown is whether multi-decadal changes in solar activity produce longer-term irradiance variations larger than observed thus far in the contemporary epoch. Empirical associations with solar activity proxies suggest reduced total solar irradiance during the anomalously low activity in the seventeenth century Maunder Minimum relative to the present. Uncertainties in understanding the physical relationships between direct magnetic modulation of solar radiative output and heliospheric modulation of cosmogenic proxies preclude definitive historical irradiance estimates, as yet.Received: 26 August 2004, Published online: 16 November 2004
Correspondence to: Claus Fröhlich 相似文献
14.
The association of Lomnický tít data of coronal green line irradiance (CI) to photospheric magnetic activity is studied for the years 1975–1994 using the Carrington rotation averaged photospheric magnetic flux data. It is found that the CI correlates well with photospheric magnetic flux of active regions and the total disk-integrated magnetic flux on longer time scales (11-year solar cycle) and fails (about 50% of the time) to show a strong dependence on shorter time scales. A comparison of the association of CI and of the 10.7 cm radio flux with the photospheric magnetic flux data indicated that the CI might basically represent the background coronal irradiance. 相似文献
15.
Ann T. Mecherikunnel 《Solar physics》1998,177(1-2):11-23
Simultaneous solar total irradiance observations performed by absolute radiometers on board satellites during the quiet-Sun period between solar cycles 21 and 22 (1985–1987), are analyzed to determine the solar total irradiance at 1 AU for the solar minimum. During the quiet-Sun period the total solar irradiance, UV irradiance, and the various solar activity indices show very little fluctuation. However, the absolute value of the solar total irradiance derived from the observations differ within the accuracy of the radiometers used in the measurements. Therefore, the question often arises about a reference value of the solar total irradiance for use in climate models and for computation of geophysical, and atmospheric parameters. This research is conducted as a part of the Solar Electromagnetic Radiation Study for Solar Cycle 22 (SOLERS22). On the basis of the study we recommended a reference value of 1367.0 ± 0.04 W m-2 for the solar total irradiance at 1 AU for a truly quiet Sun. We also find that the total solar irradiance data for the quiet-Sun period reveals strong short-term irradiance variations. 相似文献
16.
The basal component of radio emission is the radio intensity obtained after subtracting the sunspot-dependent (magneto-active) component from the observed flux and finally deducting the steady part from this subtracted value. The periodicity of this basal component of solar radio emission in the frequency band 0.245–15.4 GHz was studied both for the solar maximum (1980 and 1991) and minimum (1975 and 1986) periods. A constant periodicity of 35 days was observed in the entire radio band under study during the periods of maximum solar activity, whereas the periodicity fluctuates harmonically with frequency during the minimum periods, giving rise to an average time period of approximately 54 days. 相似文献
17.
D. Sokoloff 《Solar physics》2004,224(1-2):145-152
Based on archival observations of solar activity, we suggest a scenario for the Maunder minimum, and compare to what extent
this is reproduced by dynamo models of Grand minima. In particular, we argue that the transition into the Maunder minimum
was very abrupt, while the end of Maunder minimum was gradual, however, rather rapid as well. 相似文献
18.
Solar activity alternates between active and quiet phases with an average period of 11?years, and this is known as the Schwabe cycle. Additionally, solar activity occasionally falls into a prolonged quiet phase (grand solar minimum), as represented by the Maunder Minimum in the 17th century, when sunspots were almost absent for 70?years and the length of the Schwabe cycle increased to 14?years. To examine the consistency of the cycle length characteristics during the grand solar minima, the carbon-14 contents in single-year tree rings were measured using an accelerator mass spectrometer as an index of the solar variability during the grand solar minimum of the 4th century BC. The signal of the Schwabe cycle was detected with a statistical confidence level of higher than 95?% by wavelet analysis. This is the oldest evidence for the Schwabe cycle at the present time, and the cycle length is considered to have increased to approximately 16?years during the grand solar minimum of the 4th century BC. This result confirms the association between the increase of the Schwabe cycle length and the weakening of solar activity, and indicates the possible prolonged absence of sunspots in the 4th century BC as during the Maunder Minimum. Theoretical implications from solar dynamo theory are discussed in order to identify the trigger of prolonged sunspot absence. A possible association between the long-term solar variation around the 4th century BC and terrestrial cooling in this period is also discussed. 相似文献
19.
A “Solar Dynamo” (SODA) Index prediction of the amplitude of Solar Cycle 25 is described. The SODA Index combines values of the solar polar magnetic field and the solar spectral irradiance at 10.7 cm to create a precursor of future solar activity. The result is an envelope of solar activity that minimizes the 11-year period of the sunspot cycle. We show that the variation in time of the SODA Index is similar to several wavelet transforms of the solar spectral irradiance at 10.7 cm. Polar field predictions for Solar Cycles 21?–?24 are used to show the success of the polar field precursor in previous sunspot cycles. Using the present value of the SODA index, we estimate that the next cycle’s smoothed peak activity will be about \(140 \pm30\) solar flux units for the 10.7 cm radio flux and a Version 2 sunspot number of \(135 \pm25\). This suggests that Solar Cycle 25 will be comparable to Solar Cycle 24. The estimated peak is expected to occur near \(2025.2 \pm1.5\) year. Because the current approach uses data prior to solar minimum, these estimates may improve as the upcoming solar minimum draws closer. 相似文献
20.
The correlation coefficients of the linear regression of six solar indices versus 10.7 cm radio flux F 10.7 were analysed in solar cycles 21, 22 and 23. We also analysed the interconnection between these indices and F 10.7 with help of approximation by polynomials of second order. The indices we have studied in this paper are: the relative sunspot numbers – SSN, 530.3 nm coronal line flux – F 530, the total solar irradiance – TSI, Mg II 280 nm core-to-wing ratio UV-index, the Flare Index – FI and the counts of flares. In most cases the regressions of these solar indices vs. F 10.7 are close to the linear regression except the moments of time near the minimums and maximums of the 11-year activity. For the linear regressions, we found that correlation coefficients K corr(t) for the solar indices vs. F 10.7 and SSN dropped to their minimum values twice during each 11-year cycle. 相似文献