In most of the solar cycles, activity in the northern and southern hemispheres peaks at different times. One hemisphere peaks well before the other, and at least one of the hemispheric maxima frequently does not coincide with the whole sphere maximum. Prediction of the maximum of a hemisphere and the corresponding north–south asymmetry of a solar cycle may help to understand the mechanisms of the solar cycle, the solar-terrestrial relationship, and solar-activity influences on space weather. Here we analysed the sunspot-group data from the Greenwich Photoheliographic Results (GPR) during 1874?–?1976 and Debrecen Photoheliographic Data (DPD) during 1977?–?2017 and studied the cycle-to-cycle variations in the values of 13-month smoothed monthly mean sunspot-group area in the whole sphere (WSGA), northern hemisphere (NSGA), and southern hemisphere (SSGA) at the epochs of maxima of Sunspot Cycles 12?–?24 and at the epochs of maxima of WSGA, NSGA, and SSGA Cycles 12?–?24 (note that solar-cycle variation of a parameter is expressed as a cycle of that parameter). The cosine fits to the values of WSGA, NSGA, and SSGA at the maxima of sunspot, WSGA, NSGA, and SSGA Cycles 12?–?24, and to the values of the corresponding north–south asymmetry, suggest the existence of a ≈132-year periodicity in the activity of the northern hemisphere, a 54?–?66-year periodicity in the activity of the southern hemisphere, and a 50?–?66 year periodicity in the north–south asymmetry in activity at all the aforementioned epochs. By extrapolating the best-fit cosine curves we predicted the amplitudes and the corresponding north–south asymmetry of the 25th WSGA, NSGA, and SSGA cycles. We find that on average Solar Cycle 25 in sunspot-group area would be to some extent smaller than Solar Cycle 24 in sunspot-group area. However, by inputting the predicted amplitudes of the 25th WSGA, NSGA, and SSGA cycles relationship between sunspot-group area and sunspot number we find that the amplitude (\(130\pm 12\)) of Sunspot Cycle 25 would be slightly larger than that of reasonably small Sunspot Cycle 24. Still it confirms that the beginning of the upcoming Gleissberg cycle would take place around Solar Cycle 25. We also find that except at the maximum of NSGA Cycle 25 where the strength of activity in the northern hemisphere would be dominant, the strength of activity in the southern hemisphere would be dominant at the maximum epochs of the 25th sunspot, WSGA, and SSGA cycles.
相似文献 |
|||||||
|
|||||||
|
排序方式： 共有15条查询结果，搜索用时 15 毫秒
1.
2.
A quiescent polar crown prominence was observed at Meudon in Hα and Ca ii lines, and by EIT and SUMER on board SOHO in UV
lines from 9 to 10 March 1996. SUMER observed the prominence continuously in a scanning mode between 21:40 UT on 9 March,
and 18:13 UT on 10 March, in the nitrogen line N v (λ1238) with a 1 arc sec2 resolution. Altogether 190 prominence images (121×108 pixels) were obtained. These are presented in a movie. The prominence
is highly dynamic. Large-scale features, such as mixed loop systems and dark cavities are changing on time scales of a few
hours. Filamentary structure is evident and is changing within a few frames of the movie. A lifetime of 20–25 min for the
fine structure has been found by the autocorrelation method. We have statistically analysed the three moments of the N v line
in the prominence: line intensity, Doppler shift and linewidth, in the context of a multiple-thread model. We find that the
data are consistent with a model where the prominence is assumed to be an ensemble of small threads. In the brightest parts
of the prominence it is possible that there are many unresolved threads (15–20) along the line of sight with diameters smaller
than a few hundred kilometers. The filling factor is probably very small and in that case the structures occupy only a fraction
of the volume.
Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1005151015043 相似文献
3.
Two quiescent solar prominences were observed in July 2000 from SUMER aboard SOHO and from the two German solar telescopes at Tenerife. Two‐dimensional images taken at the VTT simultaneously in the spectral lines Hβ at 4862 Å and Ca II at 8542 Å show no significant spatial variation of their pressure‐sensitive emission ratio. Slit spectra of the Ca II 8542 Å and He I 10830 Å lines obtained at the Gregory‐Coudé telescope yield 8000 K < Tkin < 9000 K and 3 km/s < Vn–th < 8 km/s. Among the various spectral ranges observed with SUMER, we first investigate the Lyman emission lines, which were fitted by Gaussians yielding reliable spectral radiances and line widths for the series members 5 < k < 18. A determination of the level population gives for the lower series members a Boltzmann temperature of 60 000 K, the higher members being over‐populated. This temperature indicates an origin of the Lyman lines from hot surroundings of the cool prominence body seen in the ground‐based data; this also holds for the ‘hotter’ SUMER lines. 相似文献
4.
J. Zender D. Berghmans D. S. Bloomfield C. Cabanas Parada I. Dammasch A. De Groof E. D’Huys M. Dominique P. Gallagher B. Giordanengo P. A. Higgins J.-F. Hochedez M. S. Yalim B. Nicula E. Pylyser L. Sanchez-Duarte G. Schwehm D. B. Seaton A. Stanger K. Stegen S. Willems 《Solar physics》2013,286(1):93-110
The PROBA2 Science Centre (P2SC) is a small-scale science operations centre supporting the Sun observation instruments onboard PROBA2: the EUV imager Sun Watcher using APS detectors and image Processing (SWAP) and Large-Yield Radiometer (LYRA). PROBA2 is one of ESA’s small, low-cost Projects for Onboard Autonomy (PROBA) and part of ESA’s In-Orbit Technology Demonstration Programme. The P2SC is hosted at the Royal Observatory of Belgium, co-located with both Principal Investigator teams. The P2SC tasks cover science planning, instrument commanding, instrument monitoring, data processing, support of outreach activities, and distribution of science data products. PROBA missions aim for a high degree of autonomy at mission and system level, including the science operations centre. The autonomy and flexibility of the P2SC is reached by a set of web-based interfaces allowing the operators as well as the instrument teams to monitor quasi-continuously the status of the operations, allowing a quick reaction to solar events. In addition, several new concepts are implemented at instrument, spacecraft, and ground-segment levels allowing a high degree of flexibility in the operations of the instruments. This article explains the key concepts of the P2SC, emphasising the automation and the flexibility achieved in the commanding as well as the data-processing chain. 相似文献
5.
Wauters L. Dominique M. Milligan R. Dammasch I. E. Kretzschmar M. Machol J. 《Solar physics》2022,297(3):1-22
6.
Klaus Wilhelm Ingolf E. Dammasch Donald M. Hassler 《Astrophysics and Space Science》2002,282(1):189-207
The plasma conditions in the solar atmosphere and, in particular, in coronal holes are summarized, before space-borne instrumentation
for observing these regions in vacuum-ultraviolet light is briefly introduced with the Solar Ultraviolet Measurements of Emitted
Radiation (SUMER) spectrometer on the Solar and Heliospheric Observatory (SOHO) as example. Spectroscopic measurements of
small plasma jets are then analyzed in detail. Magnetic reconnection is thought to be responsible for heating the corona of
the Sun as well as accelerating the solar wind by converting magnetic energy into thermal and kinetic energies. The continuous
outflow of the fast solar wind from coronal holes on ‘open’ field lines, which reach out into interplanetary space, then requires
many reconnection events of very small scale sizes – most of them probably below the resolution capabilities of present-day
instruments. Our observations of such an event have been obtained with the Solar and Heliospheric Observatory (SOHO) providing
both high-resolution imaging and spectral information for structural and dynamical studies. We find whirling or rotating motions
as well as jets with acceleration along their propagation paths in close spatial and temporal vicinity to the coronal jet.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
Jay M. Pasachoff Evan D. Tingle Ingolf E. Dammasch Alphonse C. Sterling 《Solar physics》2011,268(1):151-163
Using mainly the 1600 Å continuum channel and also the 1216 Å Lyman-α channel (which includes some UV continuum and C iv emission) aboard the TRACE satellite, we observed the complete lifetime of a transient, bright chromospheric loop. Simultaneous observations with the SUMER instrument aboard the SOHO spacecraft revealed interesting material velocities through the Doppler effect existing above the chromospheric loop imaged with TRACE, possibly corresponding to extended nonvisible loops, or the base of an X-ray jet. 相似文献
8.
9.
EUV bi-directional jets are a prominent class of phenomena characterizing the solar transition region. Using simultaneously obtained SUMER observations in the chromospheric Si ii 1251.16 Å and C i 1251.17 Å, transition region N v 1238.8 Å and coronal Mg x 625 Å lines we show an example of a bi-directional jet observed in the chromospheric and the transition region lines but not showing any detectable signature in the coronal line. The phenomenon, however, was also clearly detected by the TRACE imager with the 171 Å filter. This discrepancy is explained here with a non-Maxwellian electron distribution which makes a significant fraction of the plasma in the TRACE 171 Å pass-band to be derived from temperatures around ≈ 300 000 K, as opposed to ≈ 800 000 K. This could have implications for other phenomena observed in the TRACE pass-bands, including the transition region ‘moss’ and the 3- and 5-min oscillations. 相似文献
10.
There are very few reports of flare signatures in the solar irradiance at H i Lyman α at 121.5 nm, i.e. the strongest line of the solar spectrum. The LYRA radiometer onboard PROBA2 has observed several flares for which unambiguous signatures have been found in its Lyman-α channel. Here we present a brief overview of these observations followed by a detailed study of one of them: the M2 flare that occurred on 8 February 2010. For this flare, the flux in the LYRA Lyman-α channel increased by 0.6 %, which represents about twice the energy radiated in the GOES soft X-ray channel and is comparable with the energy radiated in the He ii line at 30.4 nm. The Lyman-α emission represents only a minor part of the total radiated energy of this flare, for which a white-light continuum was detected. Additionally, we found that the Lyman-α flare profile follows the gradual phase but peaks before other wavelengths. This M2 flare was very localized and had a very brief impulsive phase, but more statistics are needed to determine if these factors influence the presence of a Lyman-α flare signal strong enough to appear in the solar irradiance. 相似文献
|
| 设为首页 | 免责声明 | 关于勤云 | 加入收藏 |
|
Copyright©北京勤云科技发展有限公司 京ICP备09084417号 |