共查询到20条相似文献，搜索用时 15 毫秒
1.
Jun Nishikawa 《Solar physics》1994,152(1):125-130
Spatially-resolved precise photometric observations of the whole Sun at wavelengths of 545nm (FWHM 40nm) were carried out by using the CCD solar surface photometer. Bright parts of photospheric network have contrast of several tenths of percent, and their contribution to the total irradiance is approximately half that of active region faculae. The solar irradiance variations estimated from sunspots, faculae and active network (contrast>0.3%) agreed with the ACRIM data. The quiet Sun irradiance used in the present results was different from the total irradiance at the solar minimum observed by the ACRIM, which indicates unmeasured components (contrast>0.1%) cause the 11-year cycle irradiance variation. 相似文献
2.
Variations in total solar irradiance (TSI) correlate well with changes in projected area of photospheric magnetic flux tubes
associated with dark sunspots and bright faculae in active regions and network. This correlation does not, however, rule out
possible TSI contributions from photospheric brightness inhomogeneities located outside flux tubes and spatially correlated with them. Previous reconstructions of TSI report agreement with radiometry that seems to rule out significant “extra-flux-tube” contributions.
We show that these reconstructions are more sensitive to the facular contrasts used than has been generally recognized. Measurements
with the Solar Bolometric Imager (SBI) provide the first reliable support for the relatively high, wide-band, disk-center
contrasts required to produce 10% rms agreement. Longer term bolometric imaging will be required to determine whether the
small but systematic TSI residuals we see here are caused by remaining errors in spot and facular areas and contrasts or by
extra-flux-tube brightness structures such as bright rings around sunspots or “convective stirring” around active regions. 相似文献
3.
Observations of the Sun with a 3840 Å interference filter of 12 Å full-width at half-maximum are compared with broad band filtergrams at 5300 Å and 6103 Å magnetograms. The limit for detecting faculae by the three techniques is compared. An improvement in detecting faculae at 3840 Å can be obtained by time-averaged photographs with the time-averaging done either at the telescope or in the darkroom. The former method has certain disadvantages. The 3840 Å filter can show the presence of faculae near the limb much better than white-light photographs or magnetograms. This feature makes 3840 Å filtergrams useful in conjunction with solar oblateness studies.This research was supported by company funds of The Aerospace Corporation. 相似文献
4.
A. V. Mordvinov 《Solar physics》1996,163(2):309-317
A new numerical technique is applied to study long-term variations of total solar irradiance. The background solar flux is estimated not from, e.g., a running mean but as the mode on a moving short time interval. Statistical properties of short-term variations with respect to the running mode are studied. The probability distribution function describing the data from Nimbus-7 is asymmetric and departs from a Gaussian.The ratio of time-integrated short-term negative and positive deviations shows that the energy re-radiated from faculae makes up about 40% of the energy blocked by sunspots. The amplitude and phase relations are studied between deviations which decrease and increase the irradiance. They characterize the mechanism of energy transformation with frequency. The cross-covariance analysis reveals that some parts of the energy blocked by sunspots come to the surface of the Sun after long delays. 相似文献
5.
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
6.
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
7.
In this work a new information resource located at http://www.gao.spb.ru/database/esai and hereinafter referred to as ESAI (“Extended time series of Solar Activity Indices”) is presented. ESAI includes observational,
synthetic and simulated sets to study solar magnetic field variations and their influence on the Earth. ESAI extends the ordinary
lengths of some traditional indices, parameterizing time variations of physically different characteristics of solar activity.
In particular, long-term sets of the following indices are presented: sunspot areas, the Wolf numbers, polar faculae numbers,
sunspot mean latitudes and north-south asymmetry of hemispheres for different components of activity. Some methods for making
correct conclusions from incomplete data and some criteria to estimate the reliability of the obtained information are discussed. 相似文献
8.
The effect of large-scale magnetic fields on total solar irradiance (TSI) was studied both in time–frequency and in time–longitude aspects. A continuous wavelet analysis revealed that the energy of thermomagnetic disturbances due to sunspots and faculae cascades into the magnetic network and facular macrostructure. A numerical technique of time–longitude analysis was developed to study the fine structure of temporal changes in the TSI caused by longitudinal brightness inhomogeneities and rotation of the Sun. The analysis facilitates mapping large-scale thermal inhomogeneities of the Sun and reveals patterns of radiative excesses and deficits relative to the undisturbed solar photosphere. These patterns are organized into 2- and 4-sector structures that exhibit the effects of both activity complexes and magnetically active longitudes. Large-scale patterns with radiative excess display a facular macrostructure and bright patterns in the magnetic network caused by the dissipation of large-scale thermomagnetic disturbances. Similar global-scale temperature patterns were found in the upper solar atmosphere. These temperature patterns are also causally related to long-lived magnetic fields of the Sun. During activity cycles 21–23 the patterns with radiative excess tend to be concentrated around the active longitudes which are centered at about 60° and 230° in the Carrington system. 相似文献
9.
Comparison of the long-term variation of photospheric faculae areas with that of sunspots shows that studies of faculae provide both complementary and supplementary information on the behaviour of the solar cycle. Detailed studies of the development of sunspots with respect to faculae show that there is a high degree of order over much of a given cycle, but marked differences from cycle to cycle. Within a cycle the relationship between spot and faculae areas appears to be similar for the N and S solar hemispheres, and over the early stages of a cycle it is directly related to the magnitude of the maximum sunspot number subsequently attained in that cycle.This result may well have predictive applications, and formulae are given relating the peak sunspot number to simple parameters derived from this early developmental stage. Full application to the current cycle 21 is denied due to the cessation of the Greenwich daily photoheliographic measurements, but use of the cruder weekly data suggests a maximum smoothed sunspot number of 150 ± 22.The effects of the incompatibility of the spot and faculae data, in that faculae are unobservable over a large fraction of the solar disc and also do not always develop associated spots, have been examined in a detailed study of two cycles and shown not to vitiate the results.Now at NOAA, Environmental Data Service, NGSTDC, Boulder, Colo. 80302, U.S.A. 相似文献
10.
L. Gy?ri 《Solar physics》2012,280(2):365-378
Sunspot and white light facular areas are important data for solar activity and are used, for example, in the study of the evolution of sunspots and their effect on solar irradiance. Solar Dynamic Observatory??s Helioseismic and Magnetic Imager (SDO/HMI) solar images have much higher resolution (??0.5????pixel?1) than Solar and Heliospheric Observatory??s Michelson Doppler Imager (SOHO/MDI) solar images (??2????pixel?1). This difference in image resolution has a significant impact on the sunspot and white light facular areas measured in the two datasets. We compare the area of sunspots and white light faculae derived from SDO/HMI and SOHO/MDI observations. This comparison helps the calibration of the SOHO sunspot and facular area to those in SDO observations. We also find a 0.22 degree difference between the North direction in SDO/HMI and SOHO/MDI images. 相似文献
11.
We compare the zonal-flow pattern in subsurface layers of the Sun with the distribution of surface magnetic features such as sunspots and polar faculae. We demonstrate that, in the activity belt, the butterfly pattern of sunspots coincides with the fast stream of zonal flows, although part of the sunspot distribution does spill over to the slow stream. At high latitudes, the polar faculae and zonal-flow bands have similar distributions in the spatial and temporal domains. 相似文献
12.
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
13.
V. P. Babij V. M. Efimenko V. G. Lozitsky 《Kinematics and Physics of Celestial Bodies》2011,27(4):191-196
Integral and differential distributions of sunspot diameters are studied for the last seven 11-year cycles of solar activity.
Data of the Greenwich catalogue, Pulkovo’s database, and the “Solniechnyie Dannyie” bulletin are used. We found that the average
index of integral distribution α is 6.0 for the diameters from 50 to 90 Mm and independent of the Wolf’s numbers, but it depends
on a cycle phase in the majority of cycles (four of seven), i.e., it is higher during the ascending phase, of intermediate
value during the maximum phase and minimum during the declining phase. Cycles 17, 18, and 22 behave differently: the index
α is either invariable with phase or the variations differ from the above ones. It turned out that cycles 17 and 18 are peculiar
by sunspot diameters, i.e., sunspots of up to 140–180 Mm in diameter, the largest over the last 80 years, have been observed.
Three assumptions concerning the nature of these gigantic sunspots have been proposed: (a) these sunspots occur due to changes
in differential rotation of the sun, (b) these sunspots are a certain independent statistical assembly formed in a sporadic
discrete region of the convective zone, and (c) these sunspots are surface “fragments” of the relict magnetic field of the
solar nucleus. 相似文献
14.
The Extreme Limb Photometer (ELP) has been used to measure the irradiance fluctuation of the Sun due to selected active regions. Forty-five active regions that were completely scanned at various disk positions are included in the analysis. The contribution of these active regions to a global solar irradiance fluctuation has been correlated with photometric sunspot and facular indices (PSI and PFI) using published values of sunspot and calcium plage areas. The measured ELP fluctuations are converted to a global brightness fluctuation, B/B. The sunspot component of B/B correlates with PSI with r = 0.95. The facular component of B/B correlates with PFI with r - 0.72. The expression for PFI is important to the question of energy balance between sunspots and faculae and the results presented here are not incompatible with energy balance between the two phenomena; that is the energy deficit of sunspots may be balanced by the energy excess of faculae. 相似文献
15.
Solar Feature Catalogues In Egso 总被引：1，自引：0，他引：1
V. V. Zharkova J. Aboudarham S. Zharkov S. S. Ipson A. K. Benkhalil N. Fuller 《Solar physics》2005,228(1-2):361-375
The Solar Feature Catalogues (SFCs) are created from digitized solar images using automated pattern recognition techniques
developed in the European Grid of Solar Observation (EGSO) project. The techniques were applied for detection of sunspots,
active regions and filaments in the automatically standardized full-disk solar images in Caii K1, Caii K3 and Hα taken at the Meudon Observatory and white-light images and magnetograms from SOHO/MDI. The results of automated
recognition are verified with the manual synoptic maps and available statistical data from other observatories that revealed
high detection accuracy. A structured database of the Solar Feature Catalogues is built on the MySQL server for every feature
from their recognized parameters and cross-referenced to the original observations. The SFCs are published on the Bradford
University web site http://www.cyber.brad.ac.uk/egso/SFC/ with the pre-designed web pages for a search by time, size and location. The SFCs with 9 year coverage (1996–2004) provide
any possible information that can be extracted from full disk digital solar images. Thus information can be used for deeper
investigation of the feature origin and association with other features for their automated classification and solar activity
forecast. 相似文献
16.
Sunspot number, sunspot area, and radio flux at 10.7 cm are the indices which are most frequently used to describe the long‐term solar activity. The data of the daily solar full‐disk magnetograms measured at Mount Wilson Observatory from 19 January 1970 to 31 December 2012 are utilized together with the daily observations of the three indices to probe the relationship of the full‐disk magnetic activity respectively with the indices. Cross correlation analyses of the daily magnetic field measurements at Mount Wilson observatory are taken with the daily observations of the three indices, and the statistical significance of the difference of the obtained correlation coefficients is investigated. The following results are obtained: (1) The sunspot number should be preferred to represent/reflect the full‐disk magnetic activity of the Sun to which the weak magnetic fields (outside of sunspots) mainly contribute, the sunspot area should be recommended to represent the strong magnetic activity of the Sun (in sunspots), and the 10.7 cm radio flux should be preferred to represent the full‐disk magnetic activity of the Sun (both the weak and strong magnetic fields) to which the weak magnetic fields mainly contribute. (2) On the other hand, the most recommendable index that could be used to represent/reflect the weak magnetic activity is the 10.7 cm radio flux, the most recommendable index that could be used to represent the strong magnetic activity is the sunspot area, and the most recommendable index that could be used to represent the full‐disk magnetic activity of the Sun is the 10.7cm radio flux. Additionally, the cycle characteristics of the magnetic field strengths on the solar disk are given. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
17.
The first statistical results in sunspot distributions in 1996–2004 obtained from the Solar Feature Catalogues (SFC) are presented.
A novel robust technique is developed for automated identification of sunspots on SOHO/MDI white-light (WL) full-disk solar
images. The technique applies image standardization procedures for elimination of the limb darkening and non-circular image
shape, uses edge-detection methods to find the sunspot candidates and their edges and morphological operations to smooth the
features and fill in gaps. The detected sunspots are verified with the SOHO/MDI magnetograms by strong magnetic fields being
present in sunspots. A number of physical and geometrical parameters of the detected sunspot features are extracted and stored
in the relational SFC database including umbra/penumbra masks in the form of run-length data encoding of sunspot bounding
rectangles. The detection results are verified by comparison with the manual daily detection results in Meudon and Locarno
Observatories in 2002 and by correlation (about 96%) with the 4 year sunspot areas produced manually at NOAA. Using the SFC
data, sunspot area distributions are presented in different phases of the solar cycle and hemispheres which reveals a periodicity
of the north–south asymmetry with a period of about 7–8 years. The number of sunspots increases exponentially with the area
decrease with the index slightly increasing from −1.15 (1997) to −1.34 (2001). 相似文献
18.
R. Presura V. V. Ivanov Y. Sentoku V. I. Sotnikov P. J. Laca N. Le Galloudec A. Kemp R. Mancini H. Ruhl A. L. Astanovitskiy T. E. Cowan T. Ditmire C. Chiu W. Horton P. Valanju S. Keely 《Astrophysics and Space Science》2005,298(1-2):299-303
An experimental simulation of planetary magnetospheres is being developed to investigate the formation of collisionless shocks
and their effects. Two experimental situations are considered. In both, the solar wind is simulated by laser ablation plasmas.
In one case, the “solar wind” flows across the magnetic field of a high-current discharge. In the other, a transverse magnetic
field is embedded in the plasma flow, which interacts with a conductive obstacle. The ablation plasma is created using the
“Tomcat” laser, currently emitting 5 J in a 6 ns pulse at 1 μm wavelength and irradiance above 1013 W/cm2. The “Zebra” z-pinch generator, with load current up to 1 MA and voltage up to 3.5 MV produces the magnetic fields. Hydrodynamic modeling
is used to estimate the plasma parameters achievable at the front of the plasma flow and to optimize the experiment design.
Particle-in-cell simulations reveal details of the interaction of the “solar wind” with an external magnetic field, including
flow collimation and heating effects at the stopping point. Hybrid simulations show the formation of a bow shock at the interaction
of a magnetized plasma flow with a conductor. The plasma density and the embedded field have characteristic spatial modulations
in the shock region, with abrupt jumps and fine structure on the skin depth scale. 相似文献
19.
R. E. Falco 《Solar physics》2006,234(2):213-242
We offer a new viewpoint that can explain some of the recently obtained high-resolution observations of granules and faculae.
Examining the data of Scharmer, Gudiksen, Kiselman et al. (2002) we observe many granules undergo an evolution that results in faculae emerging from within their boundaries, and
moving towards and into intergranular lanes. These faculae have a characteristic hairpin substructure. The evolving morphology
can be closely described by a fluid dynamic instability we call the “vortex/shear layer” (VSL) interaction. It occurs in all
granules whose underlying structure has vorticity when they emerge into the photosphere through the sub-photospheric turbulent
boundary layer (SPTBL). The VSL results in the creation of vortices from the distributed vorticity of the SPTBL. The subsequent
stretching of these vortices results in high amplification of vorticity, and the concurrent high amplification of the background
magnetic field. Magnetic field lines spiral around the vortices, as well as being stretched along their axis. Thus, the VSL
is also the origin of a coherent local dynamo. The spiral sheathing of high magnetic flux results in a simple explanation
for the “hot wall” effect. The VSL also creates the “dark lanes” observed by Lites, Scharmer, Berger et al. (2004) and groupings of bright hairpins/vortex sheet ensembles, which look like the ribbon faculae (Berger, Rouppe van der
Voort, Lofdahl
et al., 2004). The SPTBL results in emerging tilted granules, which when combined with the VSL create the three-dimensionality
which Lites, Scharmer, Berger et al. (2004), also observed. Both the VSL and the SPTBL result, on average, in a west side bias of hairpin faculae and granular
three-dimensionality.
An erratum to this article is available at . 相似文献
20.
Kenneth H. Schatten 《Solar physics》2009,255(1):3-38
Photospheric ephemeral regions (EPRs) cover the Sun like a magnetic carpet. From this, we update the Babcock – Leighton solar
dynamo. Rather than sunspot fields appearing in the photosphere de novo from eruptions originating in the deep interior, we consider that sunspots form directly in the photosphere by a rapid accumulation
of like-sign field from EPRs. This would only occur during special circumstances: locations and times when the temperature
structure is highly superadiabatic and contains a large subsurface horizontal magnetic field (only present in the Sun’s lower
latitudes). When these conditions are met, superadiabatic percolation occurs, wherein an inflow and downflow of gas scours
the surface of EPRs to form active regions. When these conditions are not met, magnetic elements undergo normal percolation,
wherein magnetic elements move about the photosphere in Brownian-type motions. Cellular automata (CA) models are developed
that allow these processes to be calculated and thereby both small-scale and large-scale models of magnetic motions can be
obtained. The small-scale model is compared with active region development and Hinode observations. The large-scale CA model offers a solar dynamo, which suggests that fields from decaying bipolar magnetic regions
(BMRs) drift on the photosphere driven by subsurface magnetic forces. These models are related to observations and are shown
to support Waldmeier’s findings of an inverse relationship between solar cycle length and cycle size. Evidence for significant
amounts of deep magnetic activity could disprove the model presented here, but recent helioseismic observations of “butterfly
patterns” at depth are likely just a reflection of surface activity. Their existence seems to support the contention made
here that the field and flow separate, allowing cool, relatively field-free downdrafts to descend with little field into the
nether worlds of the solar interior. There they heat by compression to form a hot solar-type Santa Ana wind deep below active
regions. 相似文献