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1.
Peter Foukal 《Solar physics》2012,279(2):365-381
We compare total solar irradiance (TSI) and ultraviolet (F uv) irradiance variation reconstructed using Ca?K facular areas since 1915, with previous values based on less direct proxies. Our annual means for 1925??C?1945 reach values 30??C?50?% higher than those presently used in IPCC climate studies. A high facula/sunspot area ratio in spot cycles 16 and 17 seems to be responsible. New evidence from solar photometry increases the likelihood of greater seventeenth century solar dimming than expected from the disappearance of magnetic active regions alone. But the large additional brightening in the early twentieth century claimed from some recent models requires complete disappearance of the magnetic network. The network is clearly visible in Ca K spectroheliograms obtained since the 1890s, so these models cannot be correct. Changes in photospheric effective temperature invoked in other models would be powerfully damped by the thermal inertia of the convection zone. Thus, there is presently no support for twentieth century irradiance variation besides that arising from active regions. The mid-twentieth century irradiance peak arising from these active regions extends 20 years beyond the early 1940s peak in global temperature. This failure of correlation, together with the low amplitude of TSI variation and the relatively weak effect of Fuv driving on tropospheric temperature, limits the role of solar irradiance variation in twentieth century global warming.  相似文献   

2.
太阳总辐照是指在地球大气层顶接收到的太阳总辐射照度,也叫"太阳常数",但它实际上并非常数。太阳总辐照随波长的分布即为太阳分光辐照。太阳辐照变化的研究,对理解太阳表面及内部活动的物理过程、机制,研究地球大气、日地关系,解决人类面临的全球气候变暖的挑战等,都具有重要意义。首先简单介绍了太阳辐照,回顾了太阳辐照的空间观测;接着介绍了观测数据的并合,以及对合成数据的一些研究;然后讨论了太阳辐照变化的原因,简述了太阳总辐照的重构及其在气候研究上的一些应用,并进行必要的评论;最后对未来的研究方向提出了一些看法。  相似文献   

3.
We found an evidence that the solar cycle luminosity modulation of the Sun deduced from the total irradiance modulation which was measured by the Earth Radiation Budget (ERB) experiment on board of Nimbus 7 from November 16, 1978 to December 13, 1993 was not in phase with the solar cycle magnetic oscillation when we used the sunspot relative number as its index. The modulation was delayed in time behind the solar cycle magnetic oscillation by an amount of about 10.3 years on the order of length of one solar cycle. In order to quantitatively evaluate the correlation between the two quantities, we devised a method to extract characteristics which were proper to a particular solar cycle by defining a new index of the correlation called multiplied correlation index (MCI). We found that the characteristics of the ERB data time profile between solar cycles 21 and 22 were more similar to those of the solar cycle magnetic oscillation between solar cycles 20 and 21 than those between solar cycles 21 and 22 and thus the time profile of the luminosity modulation from the maximum phase of solar cycle 21 to the declining phase of the solar cycle 22 corresponded to the solar cycle magnetic oscillation from the maximum phase of solar cycle 20 to the declining phase of solar cycle 21. We interpret this phenomenon as an evidence that main features of the modulation is not caused by dark sunspots and bright faculae and plages on the surface of the Sun that should instantaneously affect the luminosity modulation but is caused by time-delayed modulation of global convection by the Lorentz force of the magnetic field of the solar cycle. The delay time of about 10.3 years is the time needed for the force to modify the flows of the convection and to modulate heat flow. Thus the delay time is a function of the strength of the magnetic field oscillation of the solar cycle which is represented by amplitude of the solar cycle. Accordingly, the delay time for other time intervals of the solar cycle magnetic oscillation with different amplitudes can be different from 10.3 years for the interval of the present analysis.  相似文献   

4.
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   

5.
A possible long-term trend of the total solar irradiance could be a natural cause for climate variations on Earth. Measurement of the total solar irradiance with space radiometers started in 1978. We present a new total solar irradiance composite, with an uncertainty of ± 0.35 W m−2. From the minimum in 1995 to the maximum in 2002 the total solar irradiance increased by 1.6 W m−2. In between the minima of 1987 and 1995 the total solar irradiance increased by 0.15 W m−2.  相似文献   

6.
Sunspots have an obvious direct effect upon the visible radiant energy falling upon the Earth. We show how to estimate this effect and compare it quantitatively with recent observations of the solar total irradiance (Willson et al., 1981). The sunspots explain about half of the total observed variance of one-day averages. Since the sunspot effect on irradiance produces an asymmetry of the solar radiation, rather than (necessarily) a variation of the total luminosity, we have also estimated the sunspot population on the invisible hemisphere. This extrapolation allows us to estimate the true luminosity deficit produced by sunspots, in a manner that tends toward the correct long-term average value. We find no evidence for instantaneous global re-emission to compensate for the sunspot flux deficit.  相似文献   

7.
We have analyzed the solar irradiance data from the Earth Radiation Budget Satellite(ERBS)during the time period from 1984 October 15 to 2003 October 15.By first filtering the data by Simple Exponential Smoothing,we have applied the periodogram method to the processed data in order to search for its time variation.The study exhibits multi-periodicities on these data around 110,118,574 and 740d with very high confidence levels(more than 99%).These periods are significantly similar to the periods of other solar activities which may suggest that solar irradiance may be associated with other solar activities.  相似文献   

8.
The solar irradiance data plays a very important role for understanding of Solar internal Structure and the solar terrestrial relationships. The Total Solar Irradiance (TSI) is integrated solar energy flux over the entire spectrum which arrives at the top of the atmosphere at the mean sun earth distance. TSI has been monitored from several satellites, e.g. Nimbus 7, Solar Maximum Mission (SMM), The NASA, Earth Radiation Budget Satellite (ERBS), NOAA9, NOAA10, Eureca and the Upper Atmospheric Research Satellite (UARS) etc. From these observations it reveals that the total solar irradiance varies about a small fraction of 0.1 over solar cycle being higher during maximum solar activity condition. In the present paper we have analysed the solar irradiance data from ERBS during the time period from October 15, 1984 to October 15, 2003. First filtering the data by Simple Exponential Smoothing we have applied the Rayleigh Power Spectrum Analysis on the processed data in order to search for its time variation. Study exhibits multi-periodicities on these data around 7, 11, 42, 80, 104, 130, 160, 254, 536, 752, 1142, 1388, 2474 and 4951 days with very high confidence levels (more than 95%). Apart from these strong periods there are some other weak periods around 22, 47, 53, 67, 69, 149, 167, 365, 489 and 683 days. These periods are significantly similar with the periods of other solar activities which may suggest that solar irradiance may be associated with other solar activities.  相似文献   

9.
Long-wave energy emitted by the Earth-atmosphere into space is characterized by changes in power over time that always lag behind the changes in power of the absorbed solar radiation due to slow variation in enthalpy of the Earth-atmosphere system. Long-term variation of the solar energy radiation absorbed by the Earth remains uncompensated by the energy radiated into space over the interval of time that is determined by the thermal inertia. The basic state of the climate system is when the debit and credit sides in the Earth’s global annual mean energy budget (including the air and water envelopes) are almost always unbalanced. The annual mean balance of the heat budget of the Earth-atmosphere over a long time period will reliably define the behavior and magnitude of the energy excess accumulated by the Earth or energy deficit to allow us to determine adequately and to predict beforehand the trend and amplitude of the forthcoming climate change using the prognosis of variations in the total solar irradiance (solar constant). The decrease in solar constant has been observed since the early 1990s. The Earth as a planet will have a negative balance in the energy budget in the future as well, because the Sun is entering the decline phase of the bicentennial luminosity changes. This will lead to a drop in temperature in approximately 2014. The increase in albedo and decrease in greenhouse gas concentration in the atmosphere will result in the additional decrease in absorbed portion of the solar energy and reduced greenhouse effect. The additional drop in temperature exceeding the effect of decreased solar constant can occur as a result of successive feedback effects. A deep bicentennial minimum in solar constant is to be anticipated in 2042 ± 11 and the 19th Little Ice Age (for the last 7500 years) may occur in 2055 ± 11.  相似文献   

10.
Understanding the reasons of the cyclic variation of the total solar irradiance is one of the most challenging targets of modern astrophysics. These studies prove to be essential also for a more climatologic issue, associated to the global warming. Any attempt to determine the solar components of this phenomenon must include the effects of the magnetic field, whose strength and shape in the solar interior are far from being completely known. Modeling the presence and the effects of a magnetic field requires a 2D approach, since the assumption of radial symmetry is too limiting for this topic. We present the structure of a 2D evolution code that was purposely designed for this scope; rotation, magnetic field and turbulence can be taken into account. Some preliminary results are presented and commented.  相似文献   

11.
The Global Ozone Monitoring Experiment (GOME) is the first of a series of European satellite instruments monitoring global ozone and other relevant trace constituents in the UV/visible spectral range. On 20 April 1995, the European Space Agency (ESA) launched the GOME from Kourou, French Guyana, aboard the second European Remote Sensing satellite (ERS-2). In order to obtain the geometric albedo from the backscattered terrestrial radiance measurements, a solar irradiance measurement sequence in the spectral range between 240 nm and 790 nm is carried out once every day. The GOME solar irradiance is recorded at a moderate spectral resolution (0.2–0.4 nm), thus providing an excellent opportunity to contribute to the long-term investigation of solar flux variation associated with the 11-year solar activity cycle from space, which started in 1978 with SBUV (Solar Backscatter UV Experiment) observations on Nimbus-7 and covers solar cycles 21 and 22. This paper briefly describes the GOME spectrometer and measurement mode which are relevant to the solar viewing. Preliminary results from the solar irradiance measurements between 1995 and 1997 and comparisons to SSBUV-8 (Shuttle SBUV) in January 1996 are presented. Solar activity indices used as proxies for solar flux variation are often used to find a correlation with observed variation in atmospheric quantities, for instance, total ozone. Initial results from the GOME Mgii (280 nm) and Caii K (393 nm) solar activity index calculation are presented and discussed. The coupling of solar irradiance variability to global change is a current source of scientific and public concern. This study shows that GOME/ERS-2 (1995–2001) and the next generation of European remote sensing instruments, SCIAMACHY and GOME/METOP, have the potential to provide continuity in the measurements of solar irradiance from space well into the next century.  相似文献   

12.
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13.
Solar spectral irradiance at X-ray wavelengths show large variations over a period of solar cycle. We use X-ray irradiance data in three narrow spectral regimes deduced from Yohkoh SXT measurements to study coronal irradiance and their possible association with the activity in the lower atmosphere. Time variation of the X-ray irradiance is important in understanding the emergence of magnetic flux and the effects of such variation on the upper atmosphere of the Earth. We note that about 66% of the total (2 – 30 Å) X-ray irradiance arise from 10 to 20 Å spectral range, while 2 – 10 Å contribute only about 3% of the total. The time variation in 2 – 10 and 10 – 20 Å ranges follow each other closely. Further they follow closely the solar indices such as sunspot, F 10.7, and plage indices, although similarity in the variation of 10 – 20 Å is quite apparent. However, the variation in the other spectral band (20 – 30 Å) differ to a large extent except for the solar cycle dependent variation. We infer that in addition to the active regions, the remnants of active regions contribute considerably to the emission in this spectral range.  相似文献   

14.
Gary Rottman 《Solar physics》2005,230(1-2):7-25
The Solar Radiation and Climate Experiment (SORCE) satellite carries four scientific instruments that measure the solar radiation at the top of the Earth's atmosphere. The mission is an important flight component of NASA's Earth Observing System (EOS), which in turn is the major observational and scientific element of the U.S. Global Change Research Program. The scientific objectives of SORCE are to make daily measurements of the total solar irradiance and of spectral solar irradiance from 120 to 2000 nm with additional measurements of the energetic X-rays. Solar radiation provides the dominant energy source for the Earth system and detailed understanding of its variation is essential for atmospheric and climate studies. SORCE was launched on January 25, 2003 and has an expected lifetime through the next solar minimum in about 2007. The spacecraft and all instruments have operated flawlessly during the first 2 years, and this paper provides an overview of the mission and discusses the contributions that SORCE is making to improve understanding of the Sun's influence on the Earth environment.  相似文献   

15.
The NASA Earth Observing System (EOS) is an advanced study of Earth's long-term global changes of solid Earth, its atmosphere, and oceans and includes a coordinated collection of satellites, data systems, and modeling. The EOS program was conceived in the 1980s as part of NASA's Earth System Enterprise (ESE). The Solar Radiation and Climate Experiment (SORCE) is one of about 20 missions planned for the EOS program, and the SORCE measurement objectives include the total solar irradiance (TSI) and solar spectral irradiance (SSI) that are two of the 24 key measurement parameters defined for the EOS program. The SORCE satellite was launched in January 2003, and its observations are improving the understanding and generating new inquiry regarding how and why solar variability occurs and how it affects Earth's energy balance, atmosphere, and long-term climate changes.  相似文献   

16.
Migrating bands of weak, zonal flow, associated with the activity bands in the solar cycle, have been observed at the solar surface for some time. More recently, these flows have been probed deep within the convection zone using global helioseismology and examined in more detail close to the surface with the techniques of local helioseismology. We compare the near-surface results from global and local helioseismology using data from the Michelson Doppler Imager and the Global Oscillation Network Group with surface Doppler velocity measurements from the Mount Wilson 150-foot tower and find that the results are in reasonable agreement, with some explicable differences in detail. All of the data sets show zones of faster rotation approaching the equator from mid-latitudes during the solar cycle, with a variation at any given location that can be approximately, but not completely, described by a single sinusoid and an amplitude that does not drop off steeply below the surface.  相似文献   

17.
Our study deals with the correlations between the solar activity on the one hand and the solar irradiance above the Earth’s atmosphere and at ground level on the other. We analyzed the combined ACRIM I+II time series of the total solar irradiance (TSI), the Mauna Loa time series of terrestrial insolation data, and data of terrestrial cosmic ray fluxes. We find that the correlation between the TSI and the sunspot number is strongly non-linear. We interpret this as the net balance between brightening by faculae and darkening by sunspots where faculae dominate at low activity and sunspots dominate at high activity. Such a behavior is hitherto known from stellar analogs of the Sun in a statistical manner. We perform the same analysis for the Mauna Loa data of terrestrial insolation. Here we find that the linear relation between sunspot number and insolation shows more than 1% rise in insolation by sunspot number variations which is much stronger than for the TSI. Our conclusion is that the Earth atmosphere acts as an amplifier between space and ground, and that the amplification is probably controlled by solar activity. We suspect the cosmic rays intensity as the link between solar activity and atmospheric transparency. A Fourier analysis of the time series of insolation shows three dominant peaks: 10.5, 20.4, and 14.0 years. As a matter of fact, the cosmic rays data show the same pattern of significant peaks: 10.7, 22.4, and 14.9 years. This analogy supports our idea that the cosmic rays variation has influence on the transparency of the Earth atmosphere.  相似文献   

18.
The outer layers of Sun-like stars are regions of rapid spatial variation which modulate the p-mode frequencies by partially reflecting the constituent acoustic waves. With the accuracy that has been achieved by current solar observations, and that is expected from imminent stellar observations, this modulation can be observed from the spectra of the low-degree modes. We present a new and simple theoretical calculation to determine the leading terms in an asymptotic expansion of the outer phase of these modes, which is determined by the structure of the surface layers of the star. Our procedure is to compare the stellar envelope with a plane-parallel polytropic envelope, which we regard as a smooth reference background state. Then we can isolate a seismic signature of the acoustic phase and relate it to the stratification of the outer layers of the convection zone. One can thereby constrain theories of convection that are used to construct the convection zones of the Sun and Sun-like stars. The accuracy of the diagnostic is tested in the solar case by comparing the predicted outer phase with an exact numerical calculation.  相似文献   

19.
The tilt-angle variation of solar bipolar magnetic regions (BMRs) in space and time is a probable indicator of large-scale properties of magnetic field distribution, the dynamo and other different processes affecting the rising of magnetic flux tubes. We analyze the tilt-angle distribution and evolution of clearly oriented BMRs using sunspot position and area measurements from the Greenwich Photo-Heliographic Results (GPHR) supplemented by high-quality full-disk sunspot drawings made in the Haynald Observatory in Hungary. Our work is made on the basis of the 14th sunspot cycle and we compare our results with present theories of magnetic flux evolution in the convective zone. Our results support the assumption that the scatter of tilt angles of BMRs around Joy`s law is determined by the convective turbulence. Furthermore, we find that regular BMRs grouped by age generally do not show the phenomenon of toroidal relaxation towards the east–west direction. We interpret this by the disconnection of -loops from the bottom of the convection zone.  相似文献   

20.
We describe a method of studying the variation in the rotation of the Earth in historical times using ancient records of central solar eclipses. From the records of central eclipses covering a period of some one thousand four hundred years (7th century B.C. to 7th century A.D.), given in the Chinese annals, we selected 88 entries and calculated the rotation variation parameter ΔT. Our result shows that the Earth is spinning down at a relative rate of − (1.88 ± 0.10) × 10−10/yr.  相似文献   

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