Twisting motions of sunspot penumbral filaments

The penumbra of a sunspot is composed of numerous thin, radially extended, bright and dark filaments carrying outward gas flows (the Evershed flow). Using high-resolution images obtained by the Solar Optical Telescope aboard the solar physics satellite Hinode, we discovered a number of penumbral bright filaments revealing twisting motions about their axes. These twisting motions are observed only in penumbrae located in the direction perpendicular to the symmetry line connecting the sunspot center and the solar disk center, and the direction of the twist (that is, lateral motions of intensity fluctuation across filaments) is always from limb side to disk-center side. Thus, the twisting feature is not an actual twist or turn of filaments but a manifestation of dynamics of penumbral filaments with three-dimensional radiative transfer effects.     

Magnetic flux transport on the sun

Although most of the magnetic flux observed on the sun originates in the low-latitude sunspot belts, this flux is gradually dispersed over a much wider range of latitudes by supergranular convective motions and meridional circulation. Numerical simulations show how these transport processes interact over the 11-year sunspot cycle to produce a strong "topknot" polar field, whose existence near sunspot minimum is suggested by the observed strength of the interplanetary magnetic field and by the observed areal extent of polar coronal holes. The required rates of diffusion and flow are consistent with the decay rates of active regions and with the rotational properties of the large-scale solar magnetic field.     

A model of solar luminosity modulation by magnetic activity between 1954 and 1984

A simple model based on the changes in excess radiation from bright magnetic faculae and on changes in reduced radiation from dark spots is remarkably successful in matching the slow variations of total solar irradiance measured simultaneously by the ERB and ACRIM satellite radiometers between 1981 and 1984. This model was extended back to 1954 to reconstruct the modulation of irradiance by magnetic activity during the past three 11-year solar cycles. The model predicts that the sun is consistently brighter at activity maximum than at minimum. The 0.07 percent brightening at the peak of the last cycle in 1980 was more pronounced than the brightenings found for either of the two previous cycles, even though cycle 19, which peaked around 1957, had the largest sunspot number amplitude in the history of reliable sunspot records.     

Detection of emerging sunspot regions in the solar interior

Sunspots are regions where strong magnetic fields emerge from the solar interior and where major eruptive events occur. These energetic events can cause power outages, interrupt telecommunication and navigation services, and pose hazards to astronauts. We detected subsurface signatures of emerging sunspot regions before they appeared on the solar disc. Strong acoustic travel-time anomalies of an order of 12 to 16 seconds were detected as deep as 65,000 kilometers. These anomalies were associated with magnetic structures that emerged with an average speed of 0.3 to 0.6 kilometer per second and caused high peaks in the photospheric magnetic flux rate 1 to 2 days after the detection of the anomalies. Thus, synoptic imaging of subsurface magnetic activity may allow anticipation of large sunspot regions before they become visible, improving space weather forecast.     

Torsional oscillations of the sun

The sun's differential rotation has a cyclic pattern of change that is tightly correlated with the sunspot, or magnetic activity, cycle. This pattern can be described as a torsional oscillation, in which the solar rotation is periodically sped up or slowed down in certain zones of latitude while elsewhere the rotation remains essentially steady. The zones of anomalous rotation move on the sun in wavelike fashion, keeping pace with and flanking the zones of magnetic activity. It is uncertain whether this torsional oscillation is a globally coherent ringing of the sun or whether it is a local pattern caused by and causing local changes in the magnetic fields. In either case, it may be an important link in the connection between the rotation and the cycle that is widely believed to exist but is not yet understood.     

Polar coronal holes and cosmic-ray modulation

A comparison of the size of polar coronal holes with the cosmic-ray intensity observed during the most recent sunspot cycle shows close correspondence. This lends support to recent suggestions that the well-known sunspot-cycle modulation of cosmic rays is a three-dimensional effect, probably related to the global character of the interplanetary magnetic field.     

Magnetic flux-trapping experiment with a moving conductor

An aluminum conductor moving into and out of a magnetic field of 75 gauss traps within itself for varying lengths of time a detectable fraction of the encountered flux, which subsequently decays. A time constant of about 0.005 second, which is the order of magnitude predicted by classical electrodynamics, is measured. The result is of interest in connection with the "frozen-in field" concept of Babcock's sunspot model.     

运城市旱涝灾害与太阳黑子周期关系分析

根据1956～2007年山西省运城市的降水资料和美国观测站公布的太阳黑子活动周期的观测资料,在用Z指数对降水资料进行处理而确定旱涝等级和年份后,对太阳黑子活动周期与运城市旱涝年的相关关系进行了分析。发现运城市涝灾主要发生在太阳黑子周期的极大值年及其后第3年,旱灾则在太阳黑子周期的极值年及前后1～2年内都有可能发生。     

Changes in atmospheric carbon-14 attributed to a variable sun

The (14)C production rate in the upper atmosphere changes with time because the galactic cosmic-ray flux responsible for (14)C production is modulated by the changes in solar wind magnetic properties. The resulting changes in the atmospheric (14)C level are recorded in tree rings and are used to calculate past (14)C production rates from a carbon reservoir model that describes terrestrial carbon exchange between the atmosphere, ocean, and biosphere. These past (14)C production rate changes are compared with (14)C production rates determined from 20th-century neutron flux measurements, and a theory relating (14)C production and solar variability, as given by geomagnetic Aa indices and sunspot numbers, is developed. This theory takes into account long-term solar changes that were previously neglected. The 860-year (14)C record indicates three episodes when sunspots apparently were absent: A.D. 1654 to 1714 (Maunder minimum), 1416 to 1534 (Sp?rer minimum), and 1282 to 1342 (Wolf minimum). A less precisely defined minimum occurred near A.D. 1040. The part of this record after A.D. 1645 correlates well with the basic features of the historical record of sunspot numbers. The magnitude of the calculated (14)C production rates points to a further increase in cosmic-ray flux when sunspots are absent. This flux was greatest during the Sp?rer minimum. A record of approximate sunspot numbers and Aa indices for the current millennium is also presented.     

Stellar luminosity variations and global warming

Recent studies indicate that variation in the sun's luminosity is less than that observed in many other stars of similar magnetic activity. Current findings also indicate that in more active stars, the attenuation by faculae of sunspot luminosity modulation is less effective than in the sun at present. The sun could thus become photometrically more variable (and dimmer) if its magnetic activity exceeded present levels. But the levels of solar activity required for this to occur are not observed in carbon-14 and beryllium-10 records over the past several millennia, which indicates that such an increase in amplitude of surface magnetism-driven variations in solar luminosity is unlikely in the present epoch.     

区域高火险时段现象与太阳活动异常的关系研究

以大兴安岭林区为例，运用异常度法及回归分析方法，研究了一定空间范围内，年际森林火灾活动中间歇起伏的高火险时段（年）现象与主要天文因素－太阳黑子活动异常的定量关系，得出了太阳黑子活动是制约区域高火险时段形成与发展的重要天文因素。太阳黑子活动极小值，当年及次年易发生高火险时段，灾情可能偏重；年过火面积与前两年９月－前一年９月太阳黑子相对数均值倒数，与前一年全年太阳黑子相对数均值倒数及前一年１０月－当年     

阜新暴雨日数与太阳黑子活动周期关系研究

对太阳黑子活动周期与1951～2005年阜新暴雨日数进行了分析研究。结果发现,各太阳黑子谷值周期黑子相对数与各周期内暴雨日数相关显著,相关系数达-0.842;同时,太阳黑子谷值周期内某年的阜新暴雨日数与该年的太阳黑子数相关系数达-0.737。说明阜新暴雨日数与太阳活动有着密切的相关。这一结论将为研究暴雨发生规律及暴雨的预测、预报、农业旱涝规律提供有利的气候背景和依据。     

Solar structure and terrestrial weather

If there is indeed an effect of the variable sun on the weather, the physical cause for it remains quite elusive (12). We should keep in mind the possibility that there may be several causes and several effects. The situation may change through the 11-year sunspot cycle and the 22-year solar magnetic cycle, as well as on longer time scales. Work is proceeding at a lively pace at the institutions mentioned in this article and at many others around the world. The Soviet Union has long had considerably more workers interested in this field than has any other country. A bilateral agreement between the Soviet Union and the United States has considerably increased the interactions between workers interested in this subject, including an exchange of extended visits between the two countries. A detailed knowledge of solar causes of geomagnetic activity is only now beginning to emerge after many years of scientific efforts. This suggests that a possible successful solution to the sun-weather problem will require a similar magnitude of effort. We look forward with interest and optimism to the results of the next few years.     

Anomalous solar rotation in the early 17th century

The character of solar rotation has been examined for two periods in the early 17th century for which detailed sunspot drawings are available: A.D. 1625 through 1626 and 1642 through 1644. The first period occurred 20 years before the start of the Maunder sunspot minimum, 1645 through 1715; the second occurred just at its commencement. Solar rotation in the earlier period was much like that of today. In the later period, the equatorial velocity of the sun was faster by 3 to 5 percent and the differential rotation was enhanced by a factor of 3. The equatorial acceleration with declining solar activity is in the same sense as that found in recent Doppler data. It seems likely that the change in rotation of the solar surface between 1625 and 1645 was associated with the onset of the Maunder Minimum.     

Solar cycle signal in Earth rotation: nonstationary behavior

Following the discovery of the 11-year solar cycle signal in earth rotation, linear techniques were employed to investigate the amplitude and phase of the difference between ephemeris time and universal time (DeltaT) as a function of time. The amplitude is nonstationary. This difference was related to Delta(LOD), the difference between the length of day and its nominal value. The 11-year term in Delta(LOD) was 0.8 millisecond at the close of the 18th century and decreased below noise level from 1840 to 1860. From 1875 to 1925, Delta(LOD) was about 0.16 millisecond, and it decreased to about 0.08 millisecond by the 1950's. Except for anomalous behavior from 1797 to 1838, DeltaT lags sunspot numbers by 3.0 +/- 0.4 years. Since DeltaT lags Delta(LOD) by 2.7 years, the result is that Delta(LOD) is approximately in phase with sunspot numbers.     

近540年来长江中下游地区柑桔大冻发生规律的初步研究

本文根据自公元１４５０年来长江中下游地区柑桔大冻发生的资料，对柑桔大冻的发生规律及其与太阳黑子活动的相关性进行了初步研究。结果表明，柑桔严重冻害在５４０年里至少发生８６起，平均每１０年发生１．５６起。从长期气候变化来看，柑桔大冻并不存在周期性现象，如果说有也仅适于温暖时期的平均状况，未来几十年内柑桔大冻可能会有逐渐增加的趋势；柑桔冻害与太阳黑子活动的周期、高值年及强度均无显著的相关性     

拉尼娜事件与太阳活动对玉林市低温冷害的影响

利用SIDC研究中心1870年以来太阳黑子月和年平均相对数、NCEP数据集的Nino3区海温距平和广西玉林市5个站1958—2008年常规气象资料,初步分析了太阳活动变化和拉尼娜事件对桂东南冬季气温的影响。结果表明：太阳活动变化与拉尼娜事件发生发展有很好的对应关系,拉尼娜事件的发生使玉林冬季平均气温偏低,冬季加强型拉尼娜事件还使玉林市冬季出现长时间的低温天气。太阳活动变化对玉林市冬季气温并无直接影响,但可通过拉尼娜事件的发展间接对冬季气温变化产生影响。     

Comment on "Detection of emerging sunspot regions in the solar interior"

Ilonidis et al. (Reports, 19 August 2011, p. 993) report acoustic travel-time decreases associated with emerging sunspot regions before their appearance on the solar surface. An independent analysis using helioseismic holography does not confirm these travel-time anomalies for the four regions illustrated by Ilonidis et al. This negative finding is consistent with expectations based on current emerging flux models.     

湖北省近200年大冻年表的建立及频率特征的初步分析

本文根据历史文献灾情记载以及近代气象资料,按照一定标准,建立了湖北省过去204年(1805～2008年)大冻年表,并依据大冻年表分析了大冻的年代际变化、周期性及其与太阳黑子变化和拉马德雷现象的关系.结果表明:1)过去204年共发生大冻33次,平均每10年发生1.62次(约6.2年一遇);2)在冷期平均每10年出现2次大冻,而在暖期平均每10年出现1次大冻;3)20世纪70年代以前,大冻年存在准80、24、10、4～6年周期震荡,此后24、10年周期快速衰减,4～6年周期依然存在;4)近100年,在拉马德雷冷位相时期,大冻年平均每10年出现2.3次,重现期为4.3年;暖位相时期,大冻年平均每10年出现1.3次左右.重现期为7.5年左右;5)近200年的大冻年并不都出现在太阳黑子的峰值或谷值年,不过最近100年太阳黑子谷值年大冻出现频率增加.