Photometric measurements of solar irradiance variations due to sunspots

International Nuclear Information System (INIS)

Chapman, G.A.; Herzog, A.D.; Laico, D.E.; Lawrence, J.K.; Templer, M.S.

1989-01-01

A photometric telescope constructed to obtain photometric sunspot areas and deficits on a daily basis is described. Data from this Cartesian full disk telescope (CFDT) are analyzed with attention given to the period between June 4 and June 17, 1985 because of the availability of overlapping sunspot area and irradiance deficit data from high-resolution digital spectroheliograms made with the San Fernando Observatory 28 cm vacuum solar telescope and spectroheliograph. The CFDT sunspot deficits suggest a substantial irradiance contribution from faculae and active region plage. 23 refs

Sunspot splitting triggering an eruptive flare

Science.gov (United States)

Louis, Rohan E.; Puschmann, Klaus G.; Kliem, Bernhard; Balthasar, Horst; Denker, Carsten

2014-02-01

Aims: We investigate how the splitting of the leading sunspot and associated flux emergence and cancellation in active region NOAA 11515 caused an eruptive M5.6 flare on 2012 July 2. Methods: Continuum intensity, line-of-sight magnetogram, and dopplergram data of the Helioseismic and Magnetic Imager were employed to analyse the photospheric evolution. Filtergrams in Hα and He I 10830 Å of the Chromospheric Telescope at the Observatorio del Teide, Tenerife, track the evolution of the flare. The corresponding coronal conditions were derived from 171 Å and 304 Å images of the Atmospheric Imaging Assembly. Local correlation tracking was utilized to determine shear flows. Results: Emerging flux formed a neutral line ahead of the leading sunspot and new satellite spots. The sunspot splitting caused a long-lasting flow towards this neutral line, where a filament formed. Further flux emergence, partly of mixed polarity, as well as episodes of flux cancellation occurred repeatedly at the neutral line. Following a nearby C-class precursor flare with signs of interaction with the filament, the filament erupted nearly simultaneously with the onset of the M5.6 flare and evolved into a coronal mass ejection. The sunspot stretched without forming a light bridge, splitting unusually fast (within about a day, complete ≈6 h after the eruption) in two nearly equal parts. The front part separated strongly from the active region to approach the neighbouring active region where all its coronal magnetic connections were rooted. It also rotated rapidly (by 4.9° h-1) and caused significant shear flows at its edge. Conclusions: The eruption resulted from a complex sequence of processes in the (sub-)photosphere and corona. The persistent flows towards the neutral line likely caused the formation of a flux rope that held the filament. These flows, their associated flux cancellation, the emerging flux, and the precursor flare all contributed to the destabilization of the flux rope. We

THE FORMATION AND MAGNETIC STRUCTURES OF ACTIVE-REGION FILAMENTS OBSERVED BY NVST, SDO, AND HINODE

Energy Technology Data Exchange (ETDEWEB)

Yan, X. L.; Xue, Z. K.; Wang, J. C.; Xiang, Y. Y.; Kong, D. F.; Yang, L. H. [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650216 (China); Pan, G. M. [College of Mathematics Physics and Information Engineering, Jiaxing University, Jiaxing 314001 (China)

2015-08-15

To better understand the properties of solar active-region filaments, we present a detailed study on the formation and magnetic structures of two active-region filaments in active region NOAA 11884 during a period of four days. It is found that the shearing motion of the opposite magnetic polarities and the rotation of the small sunspots with negative polarity play an important role in the formation of two active-region filaments. During the formation of these two active-region filaments, one foot of the filaments was rooted in a small sunspot with negative polarity. The small sunspot rotated not only around another small sunspot with negative polarity, but also around the center of its umbra. By analyzing the nonlinear force-free field extrapolation using the vector magnetic fields in the photosphere, twisted structures were found in the two active-region filaments prior to their eruptions. These results imply that the magnetic fields were dragged by the shearing motion between opposite magnetic polarities and became more horizontal. The sunspot rotation twisted the horizontal magnetic fields and finally formed the twisted active-region filaments.

Essential features of long-term changes of areas and diameters of sunspot groups in solar activity cycles 12-24

Science.gov (United States)

Efimenko, V. M.; Lozitsky, V. G.

2018-06-01

We analyze the Greenwich catalog data on areas of sunspot groups of last thirteen solar cycles. Various parameters of sunspots are considered, namely: average monthly smoothed areas, maximum area for each year and equivalent diameters of groups of sunspots. The first parameter shows an exceptional power of the 19th cycle of solar activity, which appears here more contrastively than in the numbers of spots (that is, in Wolf's numbers). It was found that in the maximum areas of sunspot groups for a year there is a unique phenomenon: a short and high jump in the 18th cycle (in 1946-1947) that has no analogues in other cycles. We also studied the integral distributions for equivalent diameters and found the following: (a) the average value of the index of power-law approximation is 5.4 for the last 13 cycles and (b) there is reliable evidence of Hale's double cycle (about 44 years). Since this indicator reflects the dispersion of sunspot group diameters, the results obtained show that the convective zone of the Sun generates embryos of active regions in different statistical regimes which change with a cycle of about 44 years.

Relationship between geomagnetic classes’ activity phases and their occurrence during the sunspot cycle

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Frédéric Ouattara

2009-06-01

Full Text Available Four well known geomagnetic classes of activity such as quiet days activity, fluctuating activity, recurrent activity
and shock activity time occurrences have been determined not only by using time profile of sunspot number
Rz but also by using aa index values.
We show that recurrent wind stream activity and fluctuating activity occur in opposite phase and slow solar wind
activity during minimum phase and shock activity at the maximum phase.
It emerges from this study that fluctuating activity precedes the sunspot cycle by π/2 and the latter also precedes
recurrent activity by π/2. Thus in the majority the activities do not happen at random; the sunspot cycle starts
with quiet days activity, continues with fluctuating activity and during its maximum phase arrives shock activity.
The descending phase is characterized by the manifestation of recurrent wind stream activity.

The reconciliation of an F-region irregularity model with sunspot-cycle variations in spread-F occurrence

International Nuclear Information System (INIS)

Singleton, D.G.

1974-11-01

A recently proposed means of combining models of ionospheric F-layer peak electron density and irregularity incremental electron density (ΔN) so as to simulate the global occurrence probability of the frequency spreading component of spread-F is discussed. This procedure is then used to model experimental spread-F occurrence results. It is found possible to readily simulate the sunspot-maximum results, independently of season, with only small adjustments to the amplitudes of the empirical expressions used to ΔN in the several latitude regimes. However, at sunspot minimum and for each season, the ΔN model requires modification in the equatorial and mid-latitude regions of high irregularity incidence, before successful simulations of the spread-F data can be obtained. These modifications, which include a broadening of the equatorial region and a polewards shift to the mid-latitude region with decreasing sunspot number, are discussed in detail. It is concluded that the scintillation data base, from which the original ΔN model derives, is not sufficiently representative with regard to sunspot number and magnetic index. The use of the spread-F adaptation of the ΔN model, as well as its original scintillation version, to rectify these failings of the ΔN model are also discussed. (author)

On the evolution of magnetic and velocity fields of an originating sunspot group

International Nuclear Information System (INIS)

Bachmann, G.

1978-01-01

Magnetographic measurements were made to derive longitudinal magnetic field strengths, line-of-sight velocities and the brightness distribution in an originating sunspot group. These results and photographs of the group are used to compare the evaluation of a relatively simple active region with our present ideas about the evolution of active regions in general. We found that the total magnetic flux increased from about 4 to 20x10 20 Mx over three days. The downward flow of gas in regions with stronger magnetic fields is formed only after the magnetic field has already been bipolar for two days. The maximum velocity always occurred in the main spots of the preceding and the subsequent parts of the sunspot group. Transformation into a flow pattern, which looks like Evershed motion, is observed in the main preceding sunspot after the formation of the penumbra. The generation of new active regions by concentration and amplification of magnetic fields, under the action of supergranulation flow in photospheric layers, cannot play an important role. On the contrary, the behaviour of the active region is in agreement with the conception of rising flux tubes, out of which the gas flows down. Our observations confirm that a magnetic field strength, leading to the generation of sunspots, is attained earlier in the preceding part of the originating active region than in its subsequent part. A series of subflares occurred in the active region, when short-lived small magnetic structure elements emerged in the larger bipolar magnetic field. (author)

Observational Evidence of a Flux Rope within a Sunspot Umbra

Energy Technology Data Exchange (ETDEWEB)

Guglielmino, Salvo L.; Zuccarello, Francesca [Dipartimento di Fisica e Astronomia—Sezione Astrofisica, Università di Catania, Via S. Sofia 78, I-95125 Catania (Italy); Romano, Paolo, E-mail: salvo.guglielmino@oact.inaf.it [INAF—Osservatorio Astrofisico di Catania, Via S. Sofia 78, I-95125 Catania (Italy)

2017-09-10

We observed an elongated filamentary bright structure inside the umbra of the big sunspot in active region NOAA 12529, which differs from the light bridges usually observed in sunspots for its morphology, magnetic configuration, and velocity field. We used observations taken with the Solar Dynamic Observatory satellite to characterize this feature. Its lifetime is 5 days, during which it reaches a maximum length of about 30″. In the maps of the vertical component of the photospheric magnetic field, a portion of the feature has a polarity opposite to that of the hosting sunspot. At the same time, in the entire feature the horizontal component of the magnetic field is about 2000 G, substantially stronger than in the surrounding penumbral filaments. Doppler velocity maps reveal the presence of both upward and downward plasma motions along the structure at the photospheric level. Moreover, looking at the chromospheric level, we noted that it is located in a region corresponding to the edge of a small filament that seems rooted in the sunspot umbra. Therefore, we interpreted the bright structure as the photospheric counterpart of a flux rope touching the sunspot and giving rise to penumbral-like filaments in the umbra.

Application of the Markov chain approximation to the sunspot observations

International Nuclear Information System (INIS)

Onal, M.

1988-01-01

The positions of the 13,588 sunspot groups observed during the cycle of 1950-1960 at the Istanbul University Observatory have been corrected for the effect of differential rotation. The evolution probability of a sunspot group to the other one in the same region have been determined. By using the Markov chain approximation, the types of these groups and their transition probabilities during the following activity cycle (1950-1960), and the concentration of active regions during 1950-1960 have been estimated. The transition probabilities from the observations of the activity cycle 1960-1970 have been compared with the predicted transition probabilities and a good correlation has been noted. 5 refs.; 2 tabs

The 17 GHz active region number

Energy Technology Data Exchange (ETDEWEB)

Selhorst, C. L.; Pacini, A. A. [IP and D-Universidade do Vale do Paraíba-UNIVAP, São José dos Campos (Brazil); Costa, J. E. R. [CEA, Instituto Nacional de Pesquisas Espaciais, São José dos Campos (Brazil); Giménez de Castro, C. G.; Valio, A. [CRAAM, Universidade Presbiteriana Mackenzie, São Paulo (Brazil); Shibasaki, K., E-mail: caius@univap.br [Nobeyama Solar Radio Observatory/NAOJ, Minamisaku, Nagano 384-1305 (Japan)

2014-08-01

We report the statistics of the number of active regions (NAR) observed at 17 GHz with the Nobeyama Radioheliograph between 1992, near the maximum of cycle 22, and 2013, which also includes the maximum of cycle 24, and we compare with other activity indexes. We find that NAR minima are shorter than those of the sunspot number (SSN) and radio flux at 10.7 cm (F10.7). This shorter NAR minima could reflect the presence of active regions generated by faint magnetic fields or spotless regions, which were a considerable fraction of the counted active regions. The ratio between the solar radio indexes F10.7/NAR shows a similar reduction during the two minima analyzed, which contrasts with the increase of the ratio of both radio indexes in relation to the SSN during the minimum of cycle 23-24. These results indicate that the radio indexes are more sensitive to weaker magnetic fields than those necessary to form sunspots, of the order of 1500 G. The analysis of the monthly averages of the active region brightness temperatures shows that its long-term variation mimics the solar cycle; however, due to the gyro-resonance emission, a great number of intense spikes are observed in the maximum temperature study. The decrease in the number of these spikes is also evident during the current cycle 24, a consequence of the sunspot magnetic field weakening in the last few years.

Diode laser heterodyne observations of silicon monoxide in sunspots - A test of three sunspot models

Science.gov (United States)

Glenar, D. A.; Deming, D.; Jennings, D. E.; Kostiuk, T.; Mumma, M. J.

1983-01-01

Absorption features from the 8 micron SiO fundamental (upsilon = 1-0) and hot bands (upsilon = 2-1) have been observed in sunspots at sub-Doppler resolution using a ground-based tunable diode laser heterodyne spectrometer. The observed line widths suggest an upper limit of 0.5 km/s for the microturbulent velocity in sunspot umbrae. Since the silicon monoxide abundance is very sensitive to sunspot temperature, the measured equivalent widths permit an unambiguous determination of the temperature-pressure relation in the upper layers of the umbral atmosphere. In the region of SiO line formation (log P sub g = 3.0-4.5), the results support the sunspot model suggested by Stellmacher and Wiehr (1970).

ON MAGNETIC ACTIVITY BAND OVERLAP, INTERACTION, AND THE FORMATION OF COMPLEX SOLAR ACTIVE REGIONS

Energy Technology Data Exchange (ETDEWEB)

McIntosh, Scott W. [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307 (United States); Leamon, Robert J., E-mail: mscott@hao.ucar.edu [Department of Physics, Montana State University, Bozeman, MT 59717 (United States)

2014-11-20

Recent work has revealed a phenomenological picture of the how the ∼11 yr sunspot cycle of the Sun arises. The production and destruction of sunspots is a consequence of the latitudinal-temporal overlap and interaction of the toroidal magnetic flux systems that belong to the 22 yr magnetic activity cycle and are rooted deep in the Sun's convective interior. We present a conceptually simple extension of this work, presenting a hypothesis on how complex active regions can form as a direct consequence of the intra- and extra-hemispheric interaction taking place in the solar interior. Furthermore, during specific portions of the sunspot cycle, we anticipate that those complex active regions may be particularly susceptible to profoundly catastrophic breakdown, producing flares and coronal mass ejections of the most severe magnitude.

Image patch analysis of sunspots and active regions

Directory of Open Access Journals (Sweden)

Moon Kevin R.

2016-01-01

Full Text Available Context. Separating active regions that are quiet from potentially eruptive ones is a key issue in Space Weather applications. Traditional classification schemes such as Mount Wilson and McIntosh have been effective in relating an active region large scale magnetic configuration to its ability to produce eruptive events. However, their qualitative nature prevents systematic studies of an active region’s evolution for example. Aims. We introduce a new clustering of active regions that is based on the local geometry observed in Line of Sight magnetogram and continuum images. Methods. We use a reduced-dimension representation of an active region that is obtained by factoring the corresponding data matrix comprised of local image patches. Two factorizations can be compared via the definition of appropriate metrics on the resulting factors. The distances obtained from these metrics are then used to cluster the active regions. Results. We find that these metrics result in natural clusterings of active regions. The clusterings are related to large scale descriptors of an active region such as its size, its local magnetic field distribution, and its complexity as measured by the Mount Wilson classification scheme. We also find that including data focused on the neutral line of an active region can result in an increased correspondence between our clustering results and other active region descriptors such as the Mount Wilson classifications and the R-value. Conclusions. Matrix factorization of image patches is a promising new way of characterizing active regions. We provide some recommendations for which metrics, matrix factorization techniques, and regions of interest to use to study active regions.

Revised Sunspot Numbers and the Effects on Understanding the Sunspot Cycle

Science.gov (United States)

Hathaway, D. H.

2014-12-01

While sunspot numbers provide only limited information about the sunspot cycle, they provide that information for at least twice as many sunspot cycles as any other direct solar observation. In particular, sunspot numbers are available before, during, and immediately after the Maunder Minimum (1645-1715). The instruments and methods used to count sunspots have changed over the last 400+ years. This leads to systematic changes in the sunspot number that can mask, or artificially introduce, characteristics of the sunspot cycle. The most widely used sunspot number is the International (Wolf/Zurich) sunspot number which is now calculated at the Solar Influences Data Center in Brussels, Belgium. These numbers extend back to 1749. The Group sunspot number extends back to the first telescopic observations of the Sun in 1610. There are well-known and significant differences between these two numbers where they overlap. Recent work has helped us to understand the sources of these differences and has led to proposed revisions in the sunspot numbers. Independent studies now support many of these revisions. These revised sunspot numbers suggest changes to our understanding of the sunspot cycle itself and to our understanding of its connection to climate change.

Long-term variations in the geomagnetic activity level Part II: Ascending phases of sunspot cycles

Directory of Open Access Journals (Sweden)

V. Mussino

1994-08-01

Full Text Available Monthly averages of the Helsinki Ak-values have been reduced to the equivalent aa-indices to extend the aa-data set back to 1844. A periodicity of about five cycles was found for the correlation coefficient (r between geomagnetic indices and sunspot numbers for the ascending phases of sunspot cycles 9 to 22, confirming previous findings based on a minor number of sunspot cycles. The result is useful to researchers in topics related to solar-terrestrial physics, particularly for the interpretation of long-term trends in geomagnetic activity during the past, and to forecast geomagnetic activity levels in the future.

The evolution of flaring and non-flaring active regions

Science.gov (United States)

Kilcik, A.; Yurchyshyn, V.; Sahin, S.; Sarp, V.; Obridko, V.; Ozguc, A.; Rozelot, J. P.

2018-06-01

According to the modified Zurich classification, sunspot groups are classified into seven different classes (A, B, C, D, E, F and H) based on their morphology and evolution. In this classification, classes A and B, which are small groups, describe the beginning of sunspot evolution, while classes D, E and F describe the large and evolved groups. Class C describes the middle phase of sunspot evolution and the class H describes the end of sunspot evolution. Here, we compare the lifetime and temporal evolution of flaring and non-flaring active regions (ARs), and the flaring effect on ARs in these groups in detail for the last two solar cycles (1996 through 2016). Our main findings are as follows: (i) Flaring sunspot groups have longer lifetimes than non-flaring ones. (ii) Most of the class A, B and C flaring ARs rapidly evolve to higher classes, while this is not applicable for non-flaring ARs. More than 50 per cent of the flaring A, B and C groups changed morphologically, while the remaining D, E, F and H groups did not change remarkably after the flare activity. (iii) 75 per cent of all flaring sunspot groups are large and complex. (iv) There is a significant increase in the sunspot group area in classes A, B, C, D and H after flaring activity. In contrast, the sunspot group area of classes E and F decreased. The sunspot counts of classes D, E and F decreased as well, while classes A, B, C and H showed an increase.

Sunspot activity and influenza pandemics: a statistical assessment of the purported association.

Science.gov (United States)

Towers, S

2017-10-01

Since 1978, a series of papers in the literature have claimed to find a significant association between sunspot activity and the timing of influenza pandemics. This paper examines these analyses, and attempts to recreate the three most recent statistical analyses by Ertel (1994), Tapping et al. (2001), and Yeung (2006), which all have purported to find a significant relationship between sunspot numbers and pandemic influenza. As will be discussed, each analysis had errors in the data. In addition, in each analysis arbitrary selections or assumptions were also made, and the authors did not assess the robustness of their analyses to changes in those arbitrary assumptions. Varying the arbitrary assumptions to other, equally valid, assumptions negates the claims of significance. Indeed, an arbitrary selection made in one of the analyses appears to have resulted in almost maximal apparent significance; changing it only slightly yields a null result. This analysis applies statistically rigorous methodology to examine the purported sunspot/pandemic link, using more statistically powerful un-binned analysis methods, rather than relying on arbitrarily binned data. The analyses are repeated using both the Wolf and Group sunspot numbers. In all cases, no statistically significant evidence of any association was found. However, while the focus in this particular analysis was on the purported relationship of influenza pandemics to sunspot activity, the faults found in the past analyses are common pitfalls; inattention to analysis reproducibility and robustness assessment are common problems in the sciences, that are unfortunately not noted often enough in review.

TILT ANGLE AND FOOTPOINT SEPARATION OF SMALL AND LARGE BIPOLAR SUNSPOT REGIONS OBSERVED WITH HMI

International Nuclear Information System (INIS)

McClintock, B. H.; Norton, A. A.

2016-01-01

We investigate bipolar sunspot regions and how tilt angle and footpoint separation vary during emergence and decay. The Helioseismic and Magnetic Imager on board the Solar Dynamic Observatory collects data at a higher cadence than historical records and allows for a detailed analysis of regions over their lifetimes. We sample the umbral tilt angle, footpoint separation, and umbral area of 235 bipolar sunspot regions in Helioseismic and Magnetic Imager—Debrecen Data with an hourly cadence. We use the time when the umbral area peaks as time zero to distinguish between the emergence and decay periods of each region and we limit our analysis of tilt and separation behavior over time to within ±96 hr of time zero. Tilt angle evolution is distinctly different for regions with small (≈30 MSH), midsize (≈50 MSH), and large (≈110 MSH) maximum umbral areas, with 45 and 90 MSH being useful divisions for separating the groups. At the peak umbral area, we determine median tilt angles for small (7.°6), midsize (5.°9), and large (9.°3) regions. Within ±48 hr of the time of peak umbral area, large regions steadily increase in tilt angle, midsize regions are nearly constant, and small regions show evidence of negative tilt during emergence. A period of growth in footpoint separation occurs over a 72-hr period for all of the regions from roughly 40 to 70 Mm. The smallest bipoles (<9 MSH) are outliers in that they do not obey Joy's law and have a much smaller footpoint separation. We confirm the Muñoz-Jaramillo et al. results that the sunspots appear to be two distinct populations

Sunspot Oscillations From The Chromosphere To The Corona

Science.gov (United States)

Brynildsen, N.; Maltby, P.; Fredvik, T.; Kjeldseth-Moe, O.

The behavior of the 3 minute sunspot oscillations is studied as a function of temper- ature through the transition region using observations with CDS/SOHO and TRACE. The oscillations occur above the umbra, with amplitudes increasing to a maximum near 200 000 K, then decreasing towards higher temperatures. Deviations from pure linear oscillations are present in several cases. Power spectra of the oscillations are remarkably similar in the chromosphere and through the transition region in contra- diction to the predictions of the sunspot filter theory. The 3 minute oscillations pene- trate to the low temperature end of the corona, where they are channeled into smaller areas coinciding with the endpoints of sunspot coronal loops. This differs from the transition zone where the oscillating region covers the umbra.

Sunspot Positions and Areas from Observations by Galileo Galilei

Science.gov (United States)

Vokhmyanin, M. V.; Zolotova, N. V.

2018-02-01

Sunspot records in the seventeenth century provide important information on the solar activity before the Maunder minimum, yielding reliable sunspot indices and the solar butterfly diagram. Galilei's letters to Cardinal Francesco Barberini and Marcus Welser contain daily solar observations on 3 - 11 May, 2 June - 8 July, and 19 - 21 August 1612. These historical archives do not provide the time of observation, which results in uncertainty in the sunspot coordinates. To obtain them, we present a method that minimizes the discrepancy between the sunspot latitudes. We provide areas and heliographic coordinates of 82 sunspot groups. In contrast to Sheiner's butterfly diagram, we found only one sunspot group near the Equator. This provides a higher reliability of Galilei's drawings. Large sunspot groups are found to emerge at the same longitude in the northern hemisphere from 3 May to 21 August, which indicates an active longitude.

MODELING THE CHROMOSPHERE OF A SUNSPOT AND THE QUIET SUN

Energy Technology Data Exchange (ETDEWEB)

Avrett, E.; Tian, H. [Smithsonian Astrophysical Observatory, Cambridge, MA 02138 (United States); Landi, E. [Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Curdt, W. [Max Planck Institut für Sonnensystemfoschung, Goettingen (Germany); Wülser, J.-P. [Lockheed Martin Advanced Techonology Center (United States)

2015-10-01

Semiempirical atmospheric modeling attempts to match an observed spectrum by finding the temperature distribution and other physical parameters along the line of sight through the emitting region such that the calculated spectrum agrees with the observed one. In this paper we take the observed spectrum of a sunspot and the quiet Sun in the EUV wavelength range 668–1475 Å from the 2001 SUMER atlas of Curdt et al. to determine models of the two atmospheric regions, extending from the photosphere through the overlying chromosphere into the transition region. We solve the coupled statistical equilibrium and optically thick radiative transfer equations for a set of 32 atoms and ions. The atoms that are part of molecules are treated separately, and are excluded from the atomic abundances and atomic opacities. We compare the Mg ii k line profile observations from the Interface Region Imaging Spectrograph with the profiles calculated from the two models. The calculated profiles for the sunspot are substantially lower than the observed ones, based on the SUMER models. The only way we have found to raise the calculated Mg ii lines to agree with the observations is to introduce illumination of the sunspot from the surrounding active region.

Featured Image: Bright Dots in a Sunspot

Science.gov (United States)

Kohler, Susanna

2018-03-01

This image of a sunspot, located in in NOAA AR 12227, was captured in December 2014 by the 0.5-meter Solar Optical Telescope on board the Hinode spacecraft. This image was processed by a team of scientists led by Rahul Yadav (Udaipur Solar Observatory, Physical Research Laboratory Dewali, India) in order to examine the properties of umbral dots: transient, bright features observed in the umbral region (the central, darkest part) of a sunspot. By exploring these dots, Yadav and collaborators learned how their properties relate to the large-scale properties of the sunspots in which they form for instance, how do the number, intensities, or filling factors of dots relate to the size of a sunspots umbra? To find out more about the authors results, check out the article below.Sunspot in NOAA AR 11921. Left: umbralpenumbral boundary. Center: the isolated umbra from the sunspot. Right: The umbra with locations of umbral dots indicated by yellow plus signs. [Adapted from Yadav et al. 2018]CitationRahul Yadav et al 2018 ApJ 855 8. doi:10.3847/1538-4357/aaaeba

TRANSITION-REGION/CORONAL SIGNATURES AND MAGNETIC SETTING OF SUNSPOT PENUMBRAL JETS: HINODE (SOT/FG), Hi-C, AND SDO/AIA OBSERVATIONS

International Nuclear Information System (INIS)

Tiwari, Sanjiv K.; Moore, Ronald L.; Winebarger, Amy R.; Alpert, Shane E.

2016-01-01

Penumbral microjets (PJs) are transient narrow bright features in the chromosphere of sunspot penumbrae, first characterized by Katsukawa et al. using the Ca ii H-line filter on Hinode's Solar Optical Telescope (SOT). It was proposed that the PJs form as a result of reconnection between two magnetic components of penumbrae (spines and interspines), and that they could contribute to the transition region (TR) and coronal heating above sunspot penumbrae. We propose a modified picture of formation of PJs based on recent results on the internal structure of sunspot penumbral filaments. Using data of a sunspot from Hinode/SOT, High Resolution Coronal Imager, and different passbands of the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory, we examine whether PJs have signatures in the TR and corona. We find hardly any discernible signature of normal PJs in any AIA passbands, except for a few of them showing up in the 1600 Å images. However, we discovered exceptionally stronger jets with similar lifetimes but bigger sizes (up to 600 km wide) occurring repeatedly in a few locations in the penumbra, where evidence of patches of opposite-polarity fields in the tails of some penumbral filaments is seen in Stokes-V images. These tail PJs do display signatures in the TR. Whether they have any coronal-temperature plasma is unclear. We infer that none of the PJs, including the tail PJs, directly heat the corona in active regions significantly, but any penumbral jet might drive some coronal heating indirectly via the generation of Alfvén waves and/or braiding of the coronal field

Fractal Dimension and Maximum Sunspot Number in Solar Cycle

Directory of Open Access Journals (Sweden)

R.-S. Kim

2006-09-01

Full Text Available The fractal dimension is a quantitative parameter describing the characteristics of irregular time series. In this study, we use this parameter to analyze the irregular aspects of solar activity and to predict the maximum sunspot number in the following solar cycle by examining time series of the sunspot number. For this, we considered the daily sunspot number since 1850 from SIDC (Solar Influences Data analysis Center and then estimated cycle variation of the fractal dimension by using Higuchi's method. We examined the relationship between this fractal dimension and the maximum monthly sunspot number in each solar cycle. As a result, we found that there is a strong inverse relationship between the fractal dimension and the maximum monthly sunspot number. By using this relation we predicted the maximum sunspot number in the solar cycle from the fractal dimension of the sunspot numbers during the solar activity increasing phase. The successful prediction is proven by a good correlation (r=0.89 between the observed and predicted maximum sunspot numbers in the solar cycles.

A STATISTICAL STUDY OF FLARE PRODUCTIVITY ASSOCIATED WITH SUNSPOT PROPERTIES IN DIFFERENT MAGNETIC TYPES OF ACTIVE REGIONS

Energy Technology Data Exchange (ETDEWEB)

Yang, Ya-Hui [Institute of Space Science, National Central University, Jhongli 32001, Taiwan (China); Hsieh, Min-Shiu [Geophysical Institute, University of Alaska Fairbanks, AK 99775-7320 (United States); Yu, Hsiu-Shan [Center for Astrophysics and Space Sciences, University of California San Diego, CA 92093 (United States); Chen, P. F., E-mail: yhyang@jupiter.ss.ncu.edu.tw, E-mail: mhsieh2@alaska.edu, E-mail: hsyu@ucsd.edu, E-mail: chenpf@nju.edu.cn [School of Astronomy and Space Science, Nanjing University, Nanjing 210023 (China)

2017-01-10

It is often believed that intense flares preferentially originate from the large-size active regions (ARs) with strong magnetic fields and complex magnetic configurations. This work investigates the dependence of flare activity on the AR properties and clarifies the influence of AR magnetic parameters on the flare productivity, based on two data sets of daily sunspot and flare information as well as the GOES soft X-ray measurements and HMI vector magnetograms. By considering the evolution of magnetic complexity, we find that flare behaviors are quite different in the short- and long-lived complex ARs and the ARs with more complex magnetic configurations are likely to host more impulsive and intense flares. Furthermore, we investigate several magnetic quantities and perform the two-sample Kolmogorov–Smirnov test to examine the similarity/difference between two populations in different types of ARs. Our results demonstrate that the total source field strength on the photosphere has a good correlation with the flare activity in complex ARs. It is noted that intense flares tend to occur at the regions of strong source field in combination with an intermediate field-weighted shear angle. This result implies that the magnetic free energy provided by a complex AR could be high enough to trigger a flare eruption even with a moderate magnetic shear on the photosphere. We thus suggest that the magnetic free energy represented by the source field rather than the photospheric magnetic complexity is a better quantity to characterize the flare productivity of an AR, especially for the occurrence of intense flares.

Flow and magnetic field properties in the trailing sunspots of active region NOAA 12396

Czech Academy of Sciences Publication Activity Database

Verma, M.; Denker, C.; Boehm, F.; Balthasar, H.; Fischer, C.E.; Kuckein, C.; Gonzalez, N.B.; Berkefeld, T.; Collados Vera, M.; Diercke, A.; Feller, A.; Gonzalez Manrique, S. J.; Hofmann, A.; Lagg, A.; Nicklas, H.; Orozco Suárez, D.; Pator Yabar, A.; Rezaei, R.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Sobotka, Michal; Solanki, S.K.; Soltau, D.; Staude, J.; Strassmeier, K.G.; Volkmer, R.; von der Lühe, O.; Waldmann, T.A.

2016-01-01

Roč. 337, č. 10 (2016), s. 1090-1098 ISSN 0004-6337. [Dynamic Sun - Exploring the Many Facets of Solar Eruptive Events. Potsdam, 26.10. 2015 -29.10. 2015 ] Institutional support: RVO:67985815 Keywords : Sun * magnetic fields * sunspots Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 0.916, year: 2016

Frequently Occurring Reconnection Jets from Sunspot Light Bridges

Science.gov (United States)

Tian, Hui; Yurchyshyn, Vasyl; Peter, Hardi; Solanki, Sami K.; Young, Peter R.; Ni, Lei; Cao, Wenda; Ji, Kaifan; Zhu, Yingjie; Zhang, Jingwen; Samanta, Tanmoy; Song, Yongliang; He, Jiansen; Wang, Linghua; Chen, Yajie

2018-02-01

Solid evidence of magnetic reconnection is rarely reported within sunspots, the darkest regions with the strongest magnetic fields and lowest temperatures in the solar atmosphere. Using the world’s largest solar telescope, the 1.6 m Goode Solar Telescope, we detect prevalent reconnection through frequently occurring fine-scale jets in the Hα line wings at light bridges, the bright lanes that may divide the dark sunspot core into multiple parts. Many jets have an inverted Y-shape, shown by models to be typical of reconnection in a unipolar field environment. Simultaneous spectral imaging data from the Interface Region Imaging Spectrograph show that the reconnection drives bidirectional flows up to 200 km s‑1, and that the weakly ionized plasma is heated by at least an order of magnitude up to ∼80,000 K. Such highly dynamic reconnection jets and efficient heating should be properly accounted for in future modeling efforts of sunspots. Our observations also reveal that the surge-like activity previously reported above light bridges in some chromospheric passbands such as the Hα core has two components: the ever-present short surges likely to be related to the upward leakage of magnetoacoustic waves from the photosphere, and the occasionally occurring long and fast surges that are obviously caused by the intermittent reconnection jets.

The Flares Associated with the Dynamics of the Sunspots K. M. ...

Indian Academy of Sciences (India)

tional theory of magnetic reconnection is briefly discussed. ... between changes in the sunspots' dynamics, emerging flux region, twisting of the field ... the eventual triggering of the flares is due to proper motion of the sunspots. Using .... rotation rates obtained from the daily motion of sunspot groups with respect to their life.

ASYMMETRIC SUNSPOT ACTIVITY AND THE SOUTHWARD DISPLACEMENT OF THE HELIOSPHERIC CURRENT SHEET

International Nuclear Information System (INIS)

Wang, Y.-M.; Robbrecht, E.

2011-01-01

Observations of the interplanetary magnetic field (IMF) have suggested a statistical tendency for the heliospheric current sheet (HCS) to be shifted a few degrees southward of the heliographic equator during the period 1965-2010, particularly in the years near sunspot minimum. Using potential-field source-surface extrapolations and photospheric flux-transport simulations, we demonstrate that this southward displacement follows from Joy's law and the observed hemispheric asymmetry in the sunspot numbers, with activity being stronger in the southern (northern) hemisphere during the declining (rising) phase of cycles 20-23. The hemispheric asymmetry gives rise to an axisymmetric quadrupole field, whose equatorial zone has the sign of the leading-polarity flux in the dominant hemisphere; during the last four cycles, the polarity of the IMF around the equator thus tended to match that of the north polar field both before and after polar field reversal. However, large fluctuations are introduced by the nonaxisymmetric field components, which depend on the longitudinal distribution of sunspot activity in either hemisphere. Consistent with this model, the HCS showed an average northward displacement during cycle 19, when the 'usual' alternation was reversed and the northern hemisphere became far more active than the southern hemisphere during the declining phase of the cycle. We propose a new method for determining the north-south displacement of the HCS from coronal streamer observations.

Depressed emission between magnetic arcades near a sunspot

Science.gov (United States)

Ryabov, B. I.; Shibasaki, K.

The locations of the depressed emission in microwaves, EUV and soft X-rays are compared with each other and with the location of the plasma outflow in the active region (AR) 8535 on the Sun. We found that two open-field regions overlap the regions of depressed emission near the AR's sunspot. These two open-field regions are simulated with the potential-field source-surface (PFSS) model under radial distances of RSS = 1.8 R⊙ and RSS = 2.5 R⊙. Each open-field region is located between the arcades of the loops of the same magnetic polarity. The former open-field region covers the region of the plasma outflow, which is thus useful for the tests on connection to the heliosphere. The utmost microwave depression of the intensity in the ordinary mode (the Very Large Array 15 GHz observations) also overlaps the region of the plasma outflow and thus indicates this outflow. The lasting for eight days depression in soft X-rays and the SOHO EIT 2.84× 10-8 m images are attributed to the evacuation of as hot coronal plasma as T≥ 2× 106 K from the extended in height (``open") magnetic structures. We conclude that the AR 8535 presents the sunspot atmosphere affected by the large-scale magnetic fields.

Deciphering solar magnetic activity. I. On the relationship between the sunspot cycle and the evolution of small magnetic features

Energy Technology Data Exchange (ETDEWEB)

McIntosh, Scott W.; Wang, Xin; Markel, Robert S.; Thompson, Michael J. [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307 (United States); Leamon, Robert J.; Malanushenko, Anna V. [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Davey, Alisdair R. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Howe, Rachel [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT (United Kingdom); Krista, Larisza D. [Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80205 (United States); Cirtain, Jonathan W. [Marshall Space Flight Center, Code ZP13, Huntsville, AL 35812 (United States); Gurman, Joseph B.; Pesnell, William D., E-mail: mscott@ucar.edu [Solar Physics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2014-09-01

Sunspots are a canonical marker of the Sun's internal magnetic field which flips polarity every ∼22 yr. The principal variation of sunspots, an ∼11 yr variation, modulates the amount of the magnetic field that pierces the solar surface and drives significant variations in our star's radiative, particulate, and eruptive output over that period. This paper presents observations from the Solar and Heliospheric Observatory and Solar Dynamics Observatory indicating that the 11 yr sunspot variation is intrinsically tied to the spatio-temporal overlap of the activity bands belonging to the 22 yr magnetic activity cycle. Using a systematic analysis of ubiquitous coronal brightpoints and the magnetic scale on which they appear to form, we show that the landmarks of sunspot cycle 23 can be explained by considering the evolution and interaction of the overlapping activity bands of the longer-scale variability.

On sunspots

CERN Document Server

Galilei, Galileo; Reeves, Eileen; Helden, Albert van

2010-01-01

Galileo's telescopic discoveries, and especially his observation of sunspots, caused great debate in an age when the heavens were thought to be perfect and unchanging. Christoph Scheiner, a Jesuit mathematician, argued that sunspots were planets or moons crossing in front of the Sun. Galileo, on the other hand, countered that the spots were on or near the surface of the Sun itself, and he supported his position with a series of meticulous observations and mathematical demonstrations that eventually convinced even his rival.  On Sunspots collects the correspondenc

The photospheric vector magnetic field of a sunspot and its vertical gradient

Science.gov (United States)

Hagyard, M. J.; West, E. A.; Tandberg-Hanssen, E.; Smith, J. E.; Henze, W., Jr.; Beckers, J. M.; Bruner, E. C.; Hyder, C. L.; Gurman, J. B.; Shine, R. A.

1981-01-01

The results of direct comparisons of photospheric and transition region line-of-sight field observations of sunspots using the SMM UV spectrometer and polarimeter are reported. The analysis accompanying the data is concentrated on demonstrating that the sunspot concentrated magnetic field extends into the transition region. An observation of a sunspot on Oct. 23, 1980 at the S 18 E 03 location is used as an example. Maximum field strengths ranged from 2030-2240 gauss for large and small umbrae viewed and inclination of the field to the line-of-sight was determined for the photosphere and transition region. The distribution of the magnetic field over the sunspot and variation of the line-of-sight gradient are discussed, as are the magnitudes and gradients of the photospheric field across the penumbral-photospheric boundaries.

Vertical gradients of sunspot magnetic fields

Science.gov (United States)

Hagyard, M. J.; Teuber, D.; West, E. A.; Tandberg-Hanssen, E.; Henze, W., Jr.; Beckers, J. M.; Bruner, M.; Hyder, C. L.; Woodgate, B. E.

1983-01-01

The results of a Solar Maximum Mission (SMM) guest investigation to determine the vertical gradients of sunspot magnetic fields for the first time from coordinated observations of photospheric and transition-region fields are described. Descriptions are given of both the photospheric vector field of a sunspot, derived from observations using the NASA Marshall Space Flight Center vector magnetograph, and of the line-of-sight component in the transition region, obtained from the SMM Ultraviolet Spectrometer and Polarimeter instrument. On the basis of these data, vertical gradients of the line-of-sight magnetic field component are calculated using three methods. It is found that the vertical gradient of Bz is lower than values from previous studies and that the transition-region field occurs at a height of approximately 4000-6000 km above the photosphere.

Photoelectric observations of propagating sunspot oscillations

International Nuclear Information System (INIS)

Lites, B.W.; White, O.R.; Packman, D.

1982-01-01

The Sacramento Park Observatory Vacuum Tower Telescope and diode array were used to make repeated intensity and velocity images of a large, isolated sunspot in both a chromospheric (lambda8542 Ca II) and a photospheric (lambda5576 Fe I) line. The movie of the digital data for the chromospheric line shows clearly a relationship between the propagating umbral disturbances and the running penumbral waves. The velocities for transverse propagating of the umbral and penumbral disturbances are 60--70 km s -1 and 20--35 km s -1 , respectively. Power spectra of the oscillations show a sharp peak at a period of about 170 s in both the velocity and intensity signals. The rms velocity fluctuation of this power peak is 0.26 km s -1 . The oscillations at any given point in the sunspot are very regular, and the phase relationship between the velocity and intensity of the chromospheric oscillations is radically different than that for the quiet Sun. Our preliminary interpretation of the phase relationship involves acoustic waves with wave vector directed downwards along the magnetic field lines; however, this interpretation relies on assumptions involved in the data reduction scheme. The mechanical energy flux carried by the observed umbral disturbances does not appear to be a significant contributor to the overall energy budget of the sunspot or the surrounding active region

A Relationship Between the Solar Rotation and Activity Analysed by Tracing Sunspot Groups

Science.gov (United States)

Ruždjak, Domagoj; Brajša, Roman; Sudar, Davor; Skokić, Ivica; Poljančić Beljan, Ivana

2017-12-01

The sunspot position published in the data bases of the Greenwich Photoheliographic Results (GPR), the US Air Force Solar Optical Observing Network and National Oceanic and Atmospheric Administration (USAF/NOAA), and of the Debrecen Photoheliographic Data (DPD) in the period 1874 to 2016 were used to calculate yearly values of the solar differential-rotation parameters A and B. These differential-rotation parameters were compared with the solar-activity level. We found that the Sun rotates more differentially at the minimum than at the maximum of activity during the epoch 1977 - 2016. An inverse correlation between equatorial rotation and solar activity was found using the recently revised sunspot number. The secular decrease of the equatorial rotation rate that accompanies the increase in activity stopped in the last part of the twentieth century. It was noted that when a significant peak in equatorial rotation velocity is observed during activity minimum, the next maximum is weaker than the previous one.

Observations of the longitudinal magnetic field in the transition region and photosphere of a sunspot

Science.gov (United States)

Henze, W., Jr.; Tandberg-Hanssen, E.; Hagyard, M. J.; West, E. A.; Woodgate, B. E.; Shine, R. A.; Beckers, J. M.; Bruner, M.; Hyder, C. L.; West, E. A.

1982-01-01

The Ultraviolet Spectrometer and Polarimeter on the Solar Maximum Mission spacraft has observed for the first time the longitudinal component of the magnetic field by means of the Zeeman effect in the transition region above a sunspot. The data presented here were obtained on three days in one sunspot, have spatial resolutions of 10 arcsec and 3 arcsec, and yield maximum field strengths greater than 1000 G above the umbrae in the spot. The method of analysis, including a line-width calibration feature used during some of the observations, is described in some detail in an appendix; the line width is required for the determination of the longitudinal magnetic field from the observed circular polarization. The transition region data for one day are compared with photospheric magnetograms from the Marshall Space Flight Center. Vertical gradients of the magnetic field are compared from the two sets of data; the maximum gradients of 0.41 to 0.62 G/km occur above the umbra and agree with or are smaller than values observed previously in the photosphere and low chromosphere.

Extending Counter-streaming Motion from an Active Region Filament to a Sunspot Light Bridge

Science.gov (United States)

Wang, Haimin; Liu, Rui; Li, Qin; Liu, Chang; Deng, Na; Xu, Yan; Jing, Ju; Wang, Yuming; Cao, Wenda

2018-01-01

We analyze high-resolution observations from the 1.6 m telescope at Big Bear Solar Observatory that cover an active region filament. Counter-streaming motions are clearly observed in the filament. The northern end of the counter-streaming motions extends to a light bridge, forming a spectacular circulation pattern around a sunspot, with clockwise motion in the blue wing and counterclockwise motion in the red wing, as observed in the Hα off-bands. The apparent speed of the flow is around 10–60 km s‑1 in the filament, decreasing to 5–20 km s‑1 in the light bridge. The most intriguing results are the magnetic structure and the counter-streaming motions in the light bridge. Similar to those in the filament, the magnetic fields show a dominant transverse component in the light bridge. However, the filament is located between opposed magnetic polarities, while the light bridge is between strong fields of the same polarity. We analyze the power of oscillations with the image sequences of constructed Dopplergrams, and find that the filament’s counter-streaming motion is due to physical mass motion along fibrils, while the light bridge’s counter-streaming motion is due to oscillation in the direction along the line-of-sight. The oscillation power peaks around 4 minutes. However, the section of the light bridge next to the filament also contains a component of the extension of the filament in combination with the oscillation, indicating that some strands of the filament are extended to and rooted in that part of the light bridge.

The magnetic nature of umbra-penumbra boundary in sunspots

Science.gov (United States)

Jurčák, J.; Rezaei, R.; González, N. Bello; Schlichenmaier, R.; Vomlel, J.

2018-03-01

Context. Sunspots are the longest-known manifestation of solar activity, and their magnetic nature has been known for more than a century. Despite this, the boundary between umbrae and penumbrae, the two fundamental sunspot regions, has hitherto been solely defined by an intensity threshold. Aim. Here, we aim at studying the magnetic nature of umbra-penumbra boundaries in sunspots of different sizes, morphologies, evolutionary stages, and phases of the solar cycle. Methods: We used a sample of 88 scans of the Hinode/SOT spectropolarimeter to infer the magnetic field properties in at the umbral boundaries. We defined these umbra-penumbra boundaries by an intensity threshold and performed a statistical analysis of the magnetic field properties on these boundaries. Results: We statistically prove that the umbra-penumbra boundary in stable sunspots is characterised by an invariant value of the vertical magnetic field component: the vertical component of the magnetic field strength does not depend on the umbra size, its morphology, and phase of the solar cycle. With the statistical Bayesian inference, we find that the strength of the vertical magnetic field component is, with a likelihood of 99%, in the range of 1849-1885 G with the most probable value of 1867 G. In contrast, the magnetic field strength and inclination averaged along individual boundaries are found to be dependent on the umbral size: the larger the umbra, the stronger and more horizontal the magnetic field at its boundary. Conclusions: The umbra and penumbra of sunspots are separated by a boundary that has hitherto been defined by an intensity threshold. We now unveil the empirical law of the magnetic nature of the umbra-penumbra boundary in stable sunspots: it is an invariant vertical component of the magnetic field.

EVOLUTION OF SPINNING AND BRAIDING HELICITY FLUXES IN SOLAR ACTIVE REGION NOAA 10930

Energy Technology Data Exchange (ETDEWEB)

Ravindra, B. [Indian Institute of Astrophysics, Koramangala, Bangalore 560 034 (India); Yoshimura, Keiji [Department of Physics, Montana State University Bozeman, MT 59717 (United States); Dasso, Sergio, E-mail: ravindra@iiap.res.in, E-mail: yosimura@solar.physics.montana.edu, E-mail: dasso@df.uba.ar [Instituto de Astronomia y Fisica del Espacio (CONICET-UBA), 1428 Buenos Aires (Argentina)

2011-12-10

The line-of-sight magnetograms from Solar Optical Telescope Narrowband Filter Imager observations of NOAA Active Region 10930 have been used to study the evolution of spinning and braiding helicities over a period of five days starting from 2006 December 9. The north (N) polarity sunspot was the follower and the south (S) polarity sunspot was the leader. The N-polarity sunspot in the active region was rotating in the counterclockwise direction. The rate of rotation was small during the first two days of observations and it increased up to 8 Degree-Sign hr{sup -1} on the third day of the observations. On the fourth and fifth days it remained at 4 Degree-Sign hr{sup -1} with small undulations in its magnitude. The sunspot rotated about 260 Degree-Sign in the last three days. The S-polarity sunspot did not complete more than 20 Degree-Sign in five days. However, it changed its direction of rotation five times over a period of five days and injected both the positive and negative type of spin helicity fluxes into the corona. Through the five days, both the positive and negative sunspot regions injected equal amounts of spin helicity. The total injected helicity is predominantly negative in sign. However, the sign of the spin and braiding helicity fluxes computed over all the regions were reversed from negative to positive five times during the five-day period of observations. The reversal in spinning helicity flux was found before the onset of the X3.4-class flare, too. Though, the rotating sunspot has been observed in this active region, the braiding helicity has contributed more to the total accumulated helicity than the spinning helicity. The accumulated helicity is in excess of -7 Multiplication-Sign 10{sup 43} Mx{sup 2} over a period of five days. Before the X3.4-class flare that occurred on 2006 December 13, the rotation speed and spin helicity flux increased in the S-polarity sunspot. Before the flare, the total injected helicity was larger than -6

CHROMOSPHERIC MASS MOTIONS AND INTRINSIC SUNSPOT ROTATIONS FOR NOAA ACTIVE REGIONS 10484, 10486, AND 10488 USING ISOON DATA

International Nuclear Information System (INIS)

Hardersen, Paul S.; Balasubramaniam, K. S.; Shkolyar, Svetlana

2013-01-01

This work utilizes Improved Solar Observing Optical Network continuum (630.2 nm) and Hα (656.2 nm) data to: (1) detect and measure intrinsic sunspot rotations occurring in the photosphere and chromosphere, (2) identify and measure chromospheric filament mass motions, and (3) assess any large-scale photospheric and chromospheric mass couplings. Significant results from 2003 October 27-29, using the techniques of Brown et al., indicate significant counter-rotation between the two large sunspots in NOAA AR 10486 on October 29, as well as discrete filament mass motions in NOAA AR 10484 on October 27 that appear to be associated with at least one C-class solar flare

The sunspot databases of the Debrecen Observatory

Science.gov (United States)

Baranyi, Tünde; Gyori, Lajos; Ludmány, András

2015-08-01

We present the sunspot data bases and online tools available in the Debrecen Heliophysical Observatory: the DPD (Debrecen Photoheliographic Data, 1974 -), the SDD (SOHO/MDI-Debrecen Data, 1996-2010), the HMIDD (SDO/HMI-Debrecen Data, HMIDD, 2010-), the revised version of Greenwich Photoheliographic Data (GPR, 1874-1976) presented together with the Hungarian Historical Solar Drawings (HHSD, 1872-1919). These are the most detailed and reliable documentations of the sunspot activity in the relevant time intervals. They are very useful for studying sunspot group evolution on various time scales from hours to weeks. Time-dependent differences between the available long-term sunspot databases are investigated and cross-calibration factors are determined between them. This work has received funding from the European Community's Seventh Framework Programme (FP7/2012-2015) under grant agreement No. 284461 (eHEROES).

Association of Plages with Sunspots: A Multi-Wavelength Study Using Kodaikanal Ca ii K and Greenwich Sunspot Area Data

Energy Technology Data Exchange (ETDEWEB)

Mandal, Sudip; Chatterjee, Subhamoy; Banerjee, Dipankar, E-mail: sudip@iiap.res.in [Indian Institute of Astrophysics, Koramangala, Bangalore 560034 (India)

2017-02-01

Plages are the magnetically active chromospheric structures prominently visible in the Ca ii K line (3933.67 Å). A plage may or may not be associated with a sunspot, which is a magnetic structure visible in the solar photosphere. In this study we explore this aspect of association of plages with sunspots using the newly digitized Kodaikanal Ca ii K plage data and the Greenwich sunspot area data. Instead of using the plage index or fractional plage area and its comparison with the sunspot number, we use, to our knowledge for the first time, the individual plage areas and compare them with the sunspot area time series. Our analysis shows that these two structures, formed in two different layers, are highly correlated with each other on a timescale comparable to the solar cycle. The area and the latitudinal distributions of plages are also similar to those of sunspots. Different area thresholdings on the “butterfly diagram” reveal that plages of area ≥4 arcmin{sup 2} are mostly associated with a sunspot in the photosphere. Apart from this, we found that the cyclic properties change when plages of different sizes are considered separately. These results may help us to better understand the generation and evolution of the magnetic structures in different layers of the solar atmosphere.

On the insignificance of Herschel's sunspot correlation

Science.gov (United States)

Love, Jeffrey J.

2013-08-01

We examine William Herschel's hypothesis that solar-cycle variation of the Sun's irradiance has a modulating effect on the Earth's climate and that this is, specifically, manifested as an anticorrelation between sunspot number and the market price of wheat. Since Herschel first proposed his hypothesis in 1801, it has been regarded with both interest and skepticism. Recently, reports have been published that either support Herschel's hypothesis or rely on its validity. As a test of Herschel's hypothesis, we seek to reject a null hypothesis of a statistically random correlation between historical sunspot numbers, wheat prices in London and the United States, and wheat farm yields in the United States. We employ binary-correlation, Pearson-correlation, and frequency-domain methods. We test our methods using a historical geomagnetic activity index, well known to be causally correlated with sunspot number. As expected, the measured correlation between sunspot number and geomagnetic activity would be an unlikely realization of random data; the correlation is "statistically significant." On the other hand, measured correlations between sunspot number and wheat price and wheat yield data would be very likely realizations of random data; these correlations are "insignificant." Therefore, Herschel's hypothesis must be regarded with skepticism. We compare and contrast our results with those of other researchers. We discuss procedures for evaluating hypotheses that are formulated from historical data.

HIGH-RESOLUTION HELIOSEISMIC IMAGING OF SUBSURFACE STRUCTURES AND FLOWS OF A SOLAR ACTIVE REGION OBSERVED BY HINODE

International Nuclear Information System (INIS)

Zhao Junwei; Kosovichev, Alexander G.; Sekii, Takashi

2010-01-01

We analyze a solar active region observed by the Hinode Ca II H line using the time-distance helioseismology technique, and infer wave-speed perturbation structures and flow fields beneath the active region with a high spatial resolution. The general subsurface wave-speed structure is similar to the previous results obtained from Solar and Heliospheric Observatory/Michelson Doppler Imager observations. The general subsurface flow structure is also similar, and the downward flows beneath the sunspot and the mass circulations around the sunspot are clearly resolved. Below the sunspot, some organized divergent flow cells are observed, and these structures may indicate the existence of mesoscale convective motions. Near the light bridge inside the sunspot, hotter plasma is found beneath, and flows divergent from this area are observed. The Hinode data also allow us to investigate potential uncertainties caused by the use of phase-speed filter for short travel distances. Comparing the measurements with and without the phase-speed filtering, we find out that inside the sunspot, mean acoustic travel times are in basic agreement, but the values are underestimated by a factor of 20%-40% inside the sunspot umbra for measurements with the filtering. The initial acoustic tomography results from Hinode show a great potential of using high-resolution observations for probing the internal structure and dynamics of sunspots.

Sunspots During the Maunder Minimum from Machina Coelestis by Hevelius

Science.gov (United States)

Carrasco, V. M. S.; Álvarez, J. Villalba; Vaquero, J. M.

2015-10-01

We revisited the sunspot observations published by Johannes Hevelius in his book Machina Coelestis (1679) corresponding to the period of 1653 - 1675 (just in the middle of the Maunder Minimum). We show detailed translations of the original Latin texts describing the sunspot records and provide the general context of these sunspot observations. From this source, we present an estimate of the annual values of the group sunspot number based only on the records that explicitly inform us of the presence or absence of sunspots. Although we obtain very low values of the group sunspot number, in accordance with a grand minimum of solar activity, these values are significantly higher in general than the values provided by Hoyt and Schatten ( Solar Phys. 179, 189, 1998) for the same period.

Latitudinal migration of sunspots based on the ESAI database

Science.gov (United States)

Zhang, Juan; Li, Fu-Yu; Feng, Wen

2018-01-01

The latitudinal migration of sunspots toward the equator, which implies there is propagation of the toroidal magnetic flux wave at the base of the solar convection zone, is one of the crucial observational bases for the solar dynamo to generate a magnetic field by shearing of the pre-existing poloidal magnetic field through differential rotation. The Extended time series of Solar Activity Indices (ESAI) elongated the Greenwich observation record of sunspots by several decades in the past. In this study, ESAI’s yearly mean latitude of sunspots in the northern and southern hemispheres during the years 1854 to 1985 is utilized to statistically test whether hemispherical latitudinal migration of sunspots in a solar cycle is linear or nonlinear. It is found that a quadratic function is statistically significantly better at describing hemispherical latitudinal migration of sunspots in a solar cycle than a linear function. In addition, the latitude migration velocity of sunspots in a solar cycle decreases as the cycle progresses, providing a particular constraint for solar dynamo models. Indeed, the butterfly wing pattern with a faster latitudinal migration rate should present stronger solar activity with a shorter cycle period, and it is located at higher latitudinal position, giving evidence to support the Babcock-Leighton dynamo mechanism.

EVIDENCE FOR A TRANSITION REGION RESPONSE TO PENUMBRAL MICROJETS IN SUNSPOTS

International Nuclear Information System (INIS)

Vissers, G. J. M.; Rouppe van der Voort, L. H. M.; Carlsson, M.

2015-01-01

Penumbral microjets (PMJs) are short-lived, fine-structured, and bright jets that are generally observed in chromospheric imaging of the penumbra of sunspots. Here we investigate their potential transition region signature by combining observations with the Swedish 1-m Solar Telescope in the Ca ii H and Ca ii 8542 Å lines with ultraviolet imaging and spectroscopy obtained with the Interface Region Imaging Spectrograph (IRIS), which includes the C ii 1334/1335 Å, Si iv 1394/1403 Å, and Mg ii h and k 2803/2796 Å lines. We find a clear corresponding signal in the IRIS Mg ii k, C ii, and Si iv slit-jaw images, typically offset spatially from the Ca ii signature in the direction along the jets: from base to top, the PMJs are predominantly visible in Ca ii, Mg ii k, and C ii/Si iv, suggesting progressive heating to transition region temperatures along the jet extent. Hence, these results support the suggestion from earlier studies that PMJs may heat to transition region temperatures

The Sunspot Number and beyond : reconstructing detailed solar information over centuries

Science.gov (United States)

Lefevre, L.

2014-12-01

With four centuries of solar evolution, the International Sunspot Number (SSN) forms the longest solar time series currently available. It provides an essential reference for understanding and quantifying how the solar output has varied over decades and centuries and thus for assessing the variations of the main natural forcing on the Earth climate. Because of its importance, this unique time-series must be closely monitored for any possible biases and drifts. Here, we report about recent disagreements between solar indices, for example the sunspot sumber and the 10.7cm radio flux. Recent analyses indicate that while part of this divergence may be due to a calibration drift in the SSN, it also results from an intrinsic change in the global magnetic parameters of sunspots and solar active regions, suggesting a possible transition to a new activity regime. Going beyond the SSN series, in the framework of the TOSCA (www.cost-tosca.eu/) and SOLID (projects.pmodwrc.ch/solid/) projects, we produced a survey of all existing catalogs providing detailed sunspot information (Lefevre & Clette, 2014:10.1007/s11207-012-0184-5) and we also located different primary solar images and drawing collections that can be exploitable to complement the existing catalogs. These are first steps towards the construction of a multi-parametric time series of multiple sunspot and sunspot group properties over more than a century, allowing to reconstruct and extend the current 1-D SSN series. By bringing new spatial, morphological and evolutionary information, such a data set should bring major advances for the modeling of the solar dynamo and solar irradiance. We will present here the current status of this work. The preliminary version catalog now extends over the last 150 years. It makes use of data from DPD (http://fenyi.solarobs.unideb.hu/DPD/index.html), from the Uccle Solar Equatorial Table (USET:http://sidc.oma.be/uset/) operated by the Royal Obeservatory of Belgium, the Greenwich

Prediction on sunspot activity based on fuzzy information granulation and support vector machine

Science.gov (United States)

Peng, Lingling; Yan, Haisheng; Yang, Zhigang

2018-04-01

In order to analyze the range of sunspots, a combined prediction method of forecasting the fluctuation range of sunspots based on fuzzy information granulation (FIG) and support vector machine (SVM) was put forward. Firstly, employing the FIG to granulate sample data and extract va)alid information of each window, namely the minimum value, the general average value and the maximum value of each window. Secondly, forecasting model is built respectively with SVM and then cross method is used to optimize these parameters. Finally, the fluctuation range of sunspots is forecasted with the optimized SVM model. Case study demonstrates that the model have high accuracy and can effectively predict the fluctuation of sunspots.

Interactions between nested sunspots. 1: The formation and breakup of a delta-type sunspot

Science.gov (United States)

Gaizauskas, V.; Harvey, K. L.; Proulx, M.

1994-01-01

We investigate a nest of sunspots in which three ordinary bipolar pairs of sunspots are aligned collinearly. The usual spreading action of the growing regions brings two spots of leading polarity together (p-p collision) and forces the leading and trailing spots of the two interior regions to overlap inot a single penumbra (p-f collision), thus forming a delta-spot. We examine digitally processed images from the Ottawa River Solar Observatory of two related events inside the delta-spot 5 days after the p-f collision begins: the violent disruption of the f-umbra, and the formation in less than a day of an hydrogen-alpha filament. The evolutionary changes in shape, area, relative motions, and brightness that we measure for each spot in the elongated nest are more compatible with Parker's (1979a) hypothesis of a sunspot as a cluster of flux tubes held together by downdrafts than with the notion of a sunspot as a monolithic plug of magnetic flux. From chromospheric developments over the delta-spot, we show that a shearing motion along a polarity inversion is more effective than convergence for creating a chromospheric filament. We invoke the release of an instability, triggered by a sequence of processes lasting 1 day or more, to explain the disruption of the f-umbra in this delta-spot. We show that the sequence is initiated when the colliding p-f umbrae reach a critical separation around 3200 +/- 200 km. We present a descriptive model in which the reconnected magnetic fields block vertical transport of convective heat flux just beneath the photosphere. We observe the formation of an unusual type of penumbra adjacent to the f-polarity portion of this delta-spot just before its disruption. A tangential penumbral band grows out of disordered matter connected to the f-umbra. We present this as evidence for the extrusion of umbral magnetic flux by thermal plumes rising through a loosely bound umbra.

Coordination failure caused by sunspots

DEFF Research Database (Denmark)

Beugnot, Julie; Gürgüç, Zeynep; Øvlisen, Frederik Roose

2012-01-01

on the efficient equilibrium, we consider sunspots as a potential reason for coordination failure. We conduct an experiment with a three player 2x2x2 game in which coordination on the efficient equilibrium is easy and should normally occur. In the control session, we find almost perfect coordination on the payoff......-dominant equilibrium, but in the sunspot treatment, dis-coordination is frequent. Sunspots lead to significant inefficiency, and we conclude that sunspots can indeed cause coordination failure....

Evolution of the Sunspot Number and Solar Wind B Time Series

Science.gov (United States)

Cliver, Edward W.; Herbst, Konstantin

2018-03-01

The past two decades have witnessed significant changes in our knowledge of long-term solar and solar wind activity. The sunspot number time series (1700-present) developed by Rudolf Wolf during the second half of the 19th century was revised and extended by the group sunspot number series (1610-1995) of Hoyt and Schatten during the 1990s. The group sunspot number is significantly lower than the Wolf series before ˜1885. An effort from 2011-2015 to understand and remove differences between these two series via a series of workshops had the unintended consequence of prompting several alternative constructions of the sunspot number. Thus it has been necessary to expand and extend the sunspot number reconciliation process. On the solar wind side, after a decade of controversy, an ISSI International Team used geomagnetic and sunspot data to obtain a high-confidence time series of the solar wind magnetic field strength (B) from 1750-present that can be compared with two independent long-term (> ˜600 year) series of annual B-values based on cosmogenic nuclides. In this paper, we trace the twists and turns leading to our current understanding of long-term solar and solar wind activity.

On the relation between activity-related frequency shifts and the sunspot distribution over the solar cycle 23

Directory of Open Access Journals (Sweden)

Santos Ângela R. G.

2017-01-01

Full Text Available The activity-related variations in the solar acoustic frequencies have been known for 30 years. However, the importance of the different contributions is still not well established. With this in mind, we developed an empirical model to estimate the spot-induced frequency shifts, which takes into account the sunspot properties, such as area and latitude. The comparison between the model frequency shifts obtained from the daily sunspot records and those observed suggests that the contribution from a stochastic component to the total frequency shifts is about 30%. The remaining 70% is related to a global, long-term variation. We also propose a new observable to investigate the short-and mid-term variations of the frequency shifts, which is insensitive to the long-term variations contained in the data. On the shortest time scales the variations in the frequency shifts are strongly correlated with the variations in the total area covered by sunspots. However, a significant loss of correlation is still found, which cannot be fully explained by ignoring the invisible side of the Sun when accounting for the total sunspot area. We also verify that the times when the frequency shifts and the sunspot areas do not vary in a similar way tend to coincide with the times of the maximum amplitude of the quasi-biennial variations found in the seismic data.

CHROMOSPHERIC SUNSPOTS IN THE MILLIMETER RANGE AS OBSERVED BY THE NOBEYAMA RADIOHELIOGRAPH

Energy Technology Data Exchange (ETDEWEB)

Iwai, Kazumasa [National Institute of Information and Communications Technology, Koganei 184-8795, Tokyo (Japan); Koshiishi, Hideki [Aerospace Research and Development Directorate, Japan Aerospace Exploration Agency, Tsukuba 305-8505 (Japan); Shibasaki, Kiyoto [Nobeyama Solar Radio Observatory, National Astronomical Observatory of Japan, Minamimaki, Nagano 384-1305 (Japan); Nozawa, Satoshi; Miyawaki, Shun; Yoneya, Takuro, E-mail: kazumasa.iwai@nict.go.jp [Department of Science, Ibaraki University, Mito, Ibaraki 310-8512 (Japan)

2016-01-10

We investigate the upper chromosphere and the transition region of the sunspot umbra using the radio brightness temperature at 34 GHz (corresponding to 8.8 mm observations) as observed by the Nobeyama Radioheliograph (NoRH). Radio free–free emission in the longer millimeter range is generated around the transition region, and its brightness temperature yields the region's temperature and density distribution. We use the NoRH data at 34 GHz by applying the Steer-CLEAN image synthesis. These data and the analysis method enable us to investigate the chromospheric structures in the longer millimeter range with high spatial resolution and sufficient visibilities. We also perform simultaneous observations of one sunspot using the NoRH and the Nobeyama 45 m telescope operating at 115 GHz. We determine that 115 GHz emission mainly originates from the lower chromosphere while 34 GHz emission mainly originates from the upper chromosphere and transition region. These observational results are consistent with the radio emission characteristics estimated from current atmospheric models of the chromosphere. On the other hand, the observed brightness temperature of the umbral region is almost the same as that of the quiet region. This result is inconsistent with current sunspot models, which predict a considerably higher brightness temperature of the sunspot umbra at 34 GHz. This inconsistency suggests that the temperature of the region at which the 34 GHz radio emission becomes optically thick should be lower than that predicted by the models.

Nature's third cycle a story of sunspots

CERN Document Server

Choudhuri, Arnab Rai

2015-01-01

The cycle of day and night and the cycle of seasons are two familiar natural cycles around which many human activities are organized. But is there a third natural cycle of importance for us humans? On 13 March 1989, six million people in Canada went without electricity for many hours: a large explosion on the sun was discovered as the cause of this blackout. Such explosions occur above sunspots, dark features on the surface of the Sun that have been observed through telescopes since the time of Galileo. The number of sunspots has been found to wax and wane over a period of 11 years. Although this cycle was discovered less than two centuries ago, it is becoming increasingly important for us as human society becomes more dependent on technology. For nearly a century after its discovery, the cause of the sunspot cycle remained completely shrouded in mystery. The 1908 discovery of strong magnetic fields in sunspots made it clear that the 11-year cycle is the magnetic cycle of the sun. It is only during the last ...

Planetary tides during the Maunder sunspot minimum

International Nuclear Information System (INIS)

Smythe, C.M.; Eddy, J.A.

1977-01-01

Sun-centered planetary conjunctions and tidal potentials are here constructed for the AD1645 to 1715 period of sunspot absence, referred to as the 'Maunder Minimum'. These are found to be effectively indistinguishable from patterns of conjunctions and power spectra of tidal potential in the present era of a well established 11 year sunspot cycle. This places a new and difficult restraint on any tidal theory of sunspot formation. Problems arise in any direct gravitational theory due to the apparently insufficient forces and tidal heights involved. Proponents of the tidal hypothesis usually revert to trigger mechanisms, which are difficult to criticise or test by observation. Any tidal theory rests on the evidence of continued sunspot periodicity and the substantiation of a prolonged period of solar anomaly in the historical past. The 'Maunder Minimum' was the most drastic change in the behaviour of solar activity in the last 300 years; sunspots virtually disappeared for a 70 year period and the 11 year cycle was probably absent. During that time, however, the nine planets were all in their orbits, and planetary conjunctions and tidal potentials were indistinguishable from those of the present era, in which the 11 year cycle is well established. This provides good evidence against the tidal theory. The pattern of planetary tidal forces during the Maunder Minimum was reconstructed to investigate the possibility that the multiple planet forces somehow fortuitously cancelled at the time, that is that the positions of the slower moving planets in the 17th and early 18th centuries were such that conjunctions and tidal potentials were at the time reduced in number and force. There was no striking dissimilarity between the time of the Maunder Minimum and any period investigated. The failure of planetary conjunction patterns to reflect the drastic drop in sunspots during the Maunder Minimum casts doubt on the tidal theory of solar activity, but a more quantitative test

Sunspots Resource--From Ancient Cultures to Modern Research

Science.gov (United States)

Craig, N.

2000-10-01

Sunspots is a web-based lesson that was developed by the Science Education Gateway (SEGway) program with participants from the Exploratorium, a well known science Museum in San Francisco, UC Berkeley Space Sciences Laboratory, and teachers from several California schools. This space science resource allows 8-12 grade students to explore the nature of sunspots and the history of solar physics in its effort to understand their nature. Interviews with solar physicists and archeo-astronomers, historic images, cutting-edge NASA images, movies, and research results, as well as a student-centered sunspot research activity using NASA space science data defines this lesson. The sunspot resource is aligned with the NCTM and National Science Education Standards. It emphasizes inquiry-based methods and mathematical exercises through measurement, graphic data representation, analysis of NASA data, lastly, interpreting results and drawing conclusions. These resources have been successfully classroom tested in 4 middle schools in the San Francisco Unified School District as part of the 3-week Summer School Science curricula. Lessons learned from the Summer School 1999 will be explained. This resource includes teacher-friendly lesson plans, space science background material and student worksheets. There will be Sunspots lesson CD-ROM and printed version of the relevant classroom-ready materials and a teacher resource booklet available. Sunspot resource is brought to you by, The Science Education Gateway - SEGway - Project, and the HESSI satellite and NASA's Office of Space Science Sun-Earth Connection Education Forum.

Local Helioseismology of Emerging Active Regions: A Case Study

Science.gov (United States)

Kosovichev, Alexander G.; Zhao, Junwei; Ilonidis, Stathis

2018-04-01

Local helioseismology provides a unique opportunity to investigate the subsurface structure and dynamics of active regions and their effect on the large-scale flows and global circulation of the Sun. We use measurements of plasma flows in the upper convection zone, provided by the Time-Distance Helioseismology Pipeline developed for analysis of solar oscillation data obtained by Helioseismic and Magnetic Imager (HMI) on Solar Dynamics Observatory (SDO), to investigate the subsurface dynamics of emerging active region NOAA 11726. The active region emergence was detected in deep layers of the convection zone about 12 hours before the first bipolar magnetic structure appeared on the surface, and 2 days before the emergence of most of the magnetic flux. The speed of emergence determined by tracking the flow divergence with depth is about 1.4 km/s, very close to the emergence speed in the deep layers. As the emerging magnetic flux becomes concentrated in sunspots local converging flows are observed beneath the forming sunspots. These flows are most prominent in the depth range 1-3 Mm, and remain converging after the formation process is completed. On the larger scale converging flows around active region appear as a diversion of the zonal shearing flows towards the active region, accompanied by formation of a large-scale vortex structure. This process occurs when a substantial amount of the magnetic flux emerged on the surface, and the converging flow pattern remains stable during the following evolution of the active region. The Carrington synoptic flow maps show that the large-scale subsurface inflows are typical for active regions. In the deeper layers (10-13 Mm) the flows become diverging, and surprisingly strong beneath some active regions. In addition, the synoptic maps reveal a complex evolving pattern of large-scale flows on the scale much larger than supergranulation

A New Revision of the Solar Irradiance Climate Data Record Incorporates Recent Research into Proxies of Sunspot Darkening and the Sunspot Number Record

Science.gov (United States)

Coddington, O.; Lean, J.; Pilewskie, P.; Baranyi, T.; Snow, M. A.; Kopp, G.; Richard, E. C.; Lindholm, C.

2017-12-01

An operational climate data record (CDR) of total and spectral solar irradiance became available in November 2015 as part of the National Oceanographic and Atmospheric Administration's National Centers for Environmental Information Climate Data Record Program. The data record, which is updated quarterly, is available from 1610 to the present as yearly-average values and from 1882 to the present as monthly- and daily-averages, with associated time and wavelength-dependent uncertainties. It was developed jointly by the University of Colorado at Boulder's Laboratory for Atmospheric and Space Physics and the Naval Research Laboratory, and, together with the source code and supporting documentation, is available at https://www.ncdc.noaa.gov/cdr/. In the Solar Irradiance CDR, total solar irradiance (TSI) and solar spectral irradiance (SSI) are estimated from models that determine the changes from quiet Sun conditions arising from bright faculae and dark sunspots on the solar disk. The models are constructed using linear regression of proxies of solar sunspot and facular features with the approximately decade-long irradiance observations from the SOlar Radiation and Climate Experiment. A new revision of this data record was recently released in an ongoing effort to reduce solar irradiance uncertainties in two ways. First, the sunspot darkening proxy was revised using a new cross calibration of the current sunspot region observations made by the Solar Observing Optical Network with the historical records of the Royal Greenwich Observatory. This implementation affects modeled irradiances from 1882 - 1978. Second, the impact of a revised record of sunspot number by the Sunspot Index and Long-term Solar Observations center on modeled irradiances was assessed. This implementation provides two different reconstructions of historical, yearly-averaged irradiances from 1610-1881. Additionally, we show new, preliminary results that demonstrate improvements in modeled TSI by using

Temporal and Periodic Variations of Sunspot Counts in Flaring and Non-Flaring Active Regions

Science.gov (United States)

Kilcik, A.; Yurchyshyn, V.; Donmez, B.; Obridko, V. N.; Ozguc, A.; Rozelot, J. P.

2018-04-01

We analyzed temporal and periodic variations of sunspot counts (SSCs) in flaring (C-, M-, or X-class flares), and non-flaring active regions (ARs) for nearly three solar cycles (1986 through 2016). Our main findings are as follows: i) temporal variations of monthly means of the daily total SSCs in flaring and non-flaring ARs behave differently during a solar cycle and the behavior varies from one cycle to another; during Solar Cycle 23 temporal SSC profiles of non-flaring ARs are wider than those of flaring ARs, while they are almost the same during Solar Cycle 22 and the current Cycle 24. The SSC profiles show a multi-peak structure and the second peak of flaring ARs dominates the current Cycle 24, while the difference between peaks is less pronounced during Solar Cycles 22 and 23. The first and second SSC peaks of non-flaring ARs have comparable magnitude in the current solar cycle, while the first peak is nearly absent in the case of the flaring ARs of the same cycle. ii) Periodic variations observed in the SSCs profiles of flaring and non-flaring ARs derived from the multi-taper method (MTM) spectrum and wavelet scalograms are quite different as well, and they vary from one solar cycle to another. The largest detected period in flaring ARs is 113± 1.6 days while we detected much longer periodicities (327± 13, 312 ± 11, and 256± 8 days) in the non-flaring AR profiles. No meaningful periodicities were detected in the MTM spectrum of flaring ARs exceeding 55± 0.7 days during Solar Cycles 22 and 24, while a 113± 1.3 days period was detected in flaring ARs of Solar Cycle 23. For the non-flaring ARs the largest detected period was only 31± 0.2 days for Cycle 22 and 72± 1.3 days for the current Cycle 24, while the largest measured period was 327± 13 days during Solar Cycle 23.

Small Coronal Holes Near Active Regions as Sources of Slow Solar Wind

Energy Technology Data Exchange (ETDEWEB)

Wang, Y.-M., E-mail: yi.wang@nrl.navy.mil [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States)

2017-06-01

We discuss the nature of the small areas of rapidly diverging, open magnetic flux that form in the strong unipolar fields at the peripheries of active regions (ARs), according to coronal extrapolations of photospheric field measurements. Because such regions usually have dark counterparts in extreme-ultraviolet (EUV) images, we refer to them as coronal holes, even when they appear as narrow lanes or contain sunspots. Revisiting previously identified “AR sources” of slow solar wind from 1998 and 1999, we find that they are all associated with EUV coronal holes; the absence of well-defined He i 1083.0 nm counterparts to some of these holes is attributed to the large flux of photoionizing radiation from neighboring AR loops. Examining a number of AR-associated EUV holes during the 2014 activity maximum, we confirm that they are characterized by wind speeds of ∼300–450 km s{sup −1}, O{sup 7+}/O{sup 6+} ratios of ∼0.05–0.4, and footpoint field strengths typically of order 30 G. The close spacing between ARs at sunspot maximum limits the widths of unipolar regions and their embedded holes, while the continual emergence of new flux leads to rapid changes in the hole boundaries. Because of the highly nonradial nature of AR fields, the smaller EUV holes are often masked by the overlying canopy of loops, and may be more visible toward one solar limb than at central meridian. As sunspot activity declines, the AR remnants merge to form much larger, weaker, and longer-lived unipolar regions, which harbor the “classical” coronal holes that produce recurrent high-speed streams.

Critical frequencies of the ionospheric F1 and F2 layers during the last four solar cycles: Sunspot group type dependencies

Science.gov (United States)

Yiǧit, Erdal; Kilcik, Ali; Elias, Ana Georgina; Dönmez, Burçin; Ozguc, Atila; Yurchshyn, Vasyl; Rozelot, Jean-Pierre

2018-06-01

The long term solar activity dependencies of ionospheric F1 and F2 regions' critical frequencies (f0F1 and f0F2) are analyzed for the last four solar cycles (1976-2015). We show that the ionospheric F1 and F2 regions have different solar activity dependencies in terms of the sunspot group (SG) numbers: F1 region critical frequency (f0F1) peaks at the same time with the small SG numbers, while the f0F2 reaches its maximum at the same time with the large SG numbers, especially during the solar cycle 23. The observed differences in the sensitivity of ionospheric critical frequencies to sunspot group (SG) numbers provide a new insight into the solar activity effects on the ionosphere and space weather. While the F1 layer is influenced by the slow solar wind, which is largely associated with small SGs, the ionospheric F2 layer is more sensitive to Coronal Mass Ejections (CMEs) and fast solar winds, which are mainly produced by large SGs and coronal holes. The SG numbers maximize during of peak of the solar cycle and the number of coronal holes peaks during the sunspot declining phase. During solar minimum there are relatively less large SGs, hence reduced CME and flare activity. These results provide a new perspective for assessing how the different regions of the ionosphere respond to space weather effects.

Self-affinity and nonextensivity of sunspots

International Nuclear Information System (INIS)

Moret, M.A.

2014-01-01

In this paper we study the time series of sunspots by using two different approaches, analyzing its self-affine behavior and studying its distribution. The long-range correlation exponent α has been calculated via Detrended Fluctuation Analysis and the power law vanishes to values greater than 11 years. On the other hand, the distribution of the sunspots obeys a q-exponential decay that suggests a non-extensive behavior. This observed characteristic seems to take an alternative interpretation of the sunspots dynamics. The present findings suggest us to propose a dynamic model of sunspots formation based on a nonlinear Fokker–Planck equation. Therefore its dynamic process follows the generalized thermostatistical formalism.

Tracking the Magnetic Flux in and Around Sunspots

Energy Technology Data Exchange (ETDEWEB)

Sheeley, N. R. Jr.; Stauffer, J. R.; Thomassie, J. C.; Warren, H. P., E-mail: solsheeley@verizon.net, E-mail: harry.warren@nrl.navy.mil [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States)

2017-02-10

We have developed a procedure for tracking sunspots observed by the Helioseismic and Magnetic Imager on the Solar Dynamics Observatory and for making curvature-corrected space/time maps of the associated line-of-sight magnetic field and continuum intensity. We apply this procedure to 36 sunspots, each observed continuously for nine days around its central meridian passage time, and find that the proper motions separate into two distinct components depending on their speeds. Fast (∼3–5 km s{sup −1}) motions, comparable to Evershed flows, are produced by weak vertical fluctuations of the horizontal canopy field and recur on a timescale of 12–20 min. Slow (∼0.3–0.5 km s{sup −1}) motions diverge from a sunspot-centered ring whose location depends on the size of the sunspot, occurring in the mid-penumbra for large sunspots and at the outer edge of the penumbra for small sunspots. The slow ingoing features are contracting spokes of a quasi-vertical field of umbral polarity. These inflows disappear when the sunspot loses its penumbra, and may be related to inward-moving penumbral grain. The slow outgoing features may have either polarity depending on whether they originate from quasi-vertical fields of umbral polarity or from the outer edge of the canopy. When a sunspot decays, the penumbra and canopy disappear, and the moat becomes filled with slow outflows of umbral polarity. We apply our procedure to decaying sunspots, to long-lived sunspots, and to numerical simulations of a long-lived sunspot by Rempel.

The Maximum Free Magnetic Energy Allowed in a Solar Active Region

Science.gov (United States)

Moore, Ronald L.; Falconer, David A.

2009-01-01

Two whole-active-region magnetic quantities that can be measured from a line-of-sight magnetogram are (sup L) WL(sub SG), a gauge of the total free energy in an active region's magnetic field, and sup L(sub theta), a measure of the active region's total magnetic flux. From these two quantities measured from 1865 SOHO/MDI magnetograms that tracked 44 sunspot active regions across the 0.5 R(sub Sun) central disk, together with each active region's observed production of CMEs, X flares, and M flares, Falconer et al (2009, ApJ, submitted) found that (1) active regions have a maximum attainable free magnetic energy that increases with the magnetic size (sup L) (sub theta) of the active region, (2) in (Log (sup L)WL(sub SG), Log(sup L) theta) space, CME/flare-productive active regions are concentrated in a straight-line main sequence along which the free magnetic energy is near its upper limit, and (3) X and M flares are restricted to large active regions. Here, from (a) these results, (b) the observation that even the greatest X flares produce at most only subtle changes in active region magnetograms, and (c) measurements from MSFC vector magnetograms and from MDI line-of-sight magnetograms showing that practically all sunspot active regions have nearly the same area-averaged magnetic field strength: =- theta/A approximately equal to 300 G, where theta is the active region's total photospheric flux of field stronger than 100 G and A is the area of that flux, we infer that (1) the maximum allowed ratio of an active region's free magnetic energy to its potential-field energy is 1, and (2) any one CME/flare eruption releases no more than a small fraction (less than 10%) of the active region's free magnetic energy. This work was funded by NASA's Heliophysics Division and NSF's Division of Atmospheric Sciences.

DIVERGENT HORIZONTAL SUB-SURFACE FLOWS WITHIN ACTIVE REGION 11158

Energy Technology Data Exchange (ETDEWEB)

Jain, Kiran; Tripathy, S. C.; Hill, F., E-mail: kjain@nso.edu, E-mail: stripathy@nso.edu, E-mail: fhill@nso.edu [National Solar Observatory, 950 N Cherry Avenue, Tucson, AZ 85719 (United States)

2015-07-20

We measure the horizontal subsurface flow in a fast emerging active region (AR; NOAA 11158) using the ring-diagram technique and the Helioseismic and Magnetic Imager high spatial resolution Dopplergrams. This AR had a complex magnetic structure and displayed significant changes in morphology during its disk passage. Over a period of six days from 2011 February 11 to 16, the temporal variation in the magnitude of the total velocity is found to follow the trend of magnetic field strength. We further analyze regions of individual magnetic polarity within AR 11158 and find that the horizontal velocity components in these sub-regions have significant variation with time and depth. The leading and trailing polarity regions move faster than the mixed-polarity region. Furthermore, both zonal and meridional components have opposite signs for trailing and leading polarity regions at all depths showing divergent flows within the AR. We also find a sharp decrease in the magnitude of total horizontal velocity in deeper layers around major flares. It is suggested that the re-organization of magnetic fields during flares, combined with the sunspot rotation, decreases the magnitude of horizontal flows or that the flow kinetic energy has been converted into the energy released by flares. After the decline in flare activity and sunspot rotation, the flows tend to follow the pattern of magnetic activity. We also observe less variation in the velocity components near the surface but these tend to increase with depth, further demonstrating that the deeper layers are more affected by the topology of ARs.

Probing sunspots with two-skip time-distance helioseismology

Science.gov (United States)

Duvall, Thomas L., Jr.; Cally, Paul S.; Przybylski, Damien; Nagashima, Kaori; Gizon, Laurent

2018-06-01

Context. Previous helioseismology of sunspots has been sensitive to both the structural and magnetic aspects of sunspot structure. Aims: We aim to develop a technique that is insensitive to the magnetic component so the two aspects can be more readily separated. Methods: We study waves reflected almost vertically from the underside of a sunspot. Time-distance helioseismology was used to measure travel times for the waves. Ray theory and a detailed sunspot model were used to calculate travel times for comparison. Results: It is shown that these large distance waves are insensitive to the magnetic field in the sunspot. The largest travel time differences for any solar phenomena are observed. Conclusions: With sufficient modeling effort, these should lead to better understanding of sunspot structure.

A model of a sunspot chromosphere based on OSO 8 observations

Science.gov (United States)

Lites, B. W.; Skumanich, A.

1982-01-01

OSO 8 spectrometer observations of the H I, Mg II, and Ca II resonance lines of a large quiet sunspot during November 16-17, 1975, along with a C IV line of that event obtained by a ground-based spectrometer, are analyzed together with near-simultaneous ground-based Stokes measurements to yield an umbral chromosphere and transition region model. Features of this model include a chromosphere that is effectively thin in the resonance lines of H I and Mg II, while being saturated in Ca II, and an upper chromospheric structure similar to that of quiet-sun models. The similarity of the upper chromosphere of the sunspot umbra to the quiet-sun chromosphere suggests that the intense magnetic field plays only a passive role in the chromospheric heating mechanism, and the observations cited indicate that solar-type stars with large areas of ordered magnetic flux would not necessarily exhibit extremely active chromosphere.

Possibility to explain the temperature distribution in sunspots by an anisotropic heat transfer

Energy Technology Data Exchange (ETDEWEB)

Eschrich, K O; Krause, F [Akademie der Wissenschaften der DDR, Potsdam. Zentralinstitut fuer Astrophysik

1977-01-01

Numerical solutions of a heat conduction problem in an anisotropic medium are used for a discussion of the possibility to explain the temperature distribution in sunspots and their environment. The anisotropy is assumed being due to the strong magnetic field in sunspots and the region below. This magnetic field forces the convection to take an anisotropic structure (two-dimensional turbulence) and thus the region gets anisotropic conduction properties, on the average. The discussion shows that the observed temperature profiles can be explained in the case the depth of the region of anisotropy is about as large as the diameter of the spot or larger.

Sunspot Light Walls Suppressed by Nearby Brightenings

Energy Technology Data Exchange (ETDEWEB)

Yang, Shuhong; Zhang, Jun; Hou, Yijun; Li, Xiaohong [CAS Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Erdélyi, Robertus [Solar Physics and Space Plasma Research Centre, School of Mathematics and Statistics, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom); Yan, Limei, E-mail: shuhongyang@nao.cas.cn [Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029 (China)

2017-07-01

Light walls, as ensembles of oscillating bright structures rooted in sunspot light bridges, have not been well studied, although they are important for understanding sunspot properties. Using the Interface Region Imaging Spectrograph and Solar Dynamics Observatory observations, here we study the evolution of two oscillating light walls each within its own active region (AR). The emission of each light wall decays greatly after the appearance of adjacent brightenings. For the first light wall, rooted within AR 12565, the average height, amplitude, and oscillation period significantly decrease from 3.5 Mm, 1.7 Mm, and 8.5 minutes to 1.6 Mm, 0.4 Mm, and 3.0 minutes, respectively. For the second light wall, rooted within AR 12597, the mean height, amplitude, and oscillation period of the light wall decrease from 2.1 Mm, 0.5 Mm, and 3.0 minutes to 1.5 Mm, 0.2 Mm, and 2.1 minutes, respectively. Particularly, a part of the second light wall even becomes invisible after the influence of a nearby brightening. These results reveal that the light walls are suppressed by nearby brightenings. Considering the complex magnetic topology in light bridges, we conjecture that the fading of light walls may be caused by a drop in the magnetic pressure, where the flux is canceled by magnetic reconnection at the site of the nearby brightening. Another hypothesis is that the wall fading is due to the suppression of driver source ( p -mode oscillation), resulting from the nearby avalanche of downward particles along reconnected brightening loops.

Towards a first detailed reconstruction of sunspot information over the last 150 years

Science.gov (United States)

Lefevre, Laure; Clette, Frédéric

2013-04-01

With four centuries of solar evolution, the International Sunspot Number (SSN) forms the longest solar time series currently available. It provides an essential reference for understanding and quantifying how the solar output has varied over decades and centuries and thus for assessing the variations of the main natural forcing on the Earth climate. For such a quantitative use, this unique time-series must be closely monitored for any possible biases and drifts. This is the main objective of the Sunspot Workshops organized jointly by the National Solar Observatory (NSO) and the Royal Observatory of Belgium (ROB) since 2010. Here, we will report about some recent outcomes of past workshops, like diagnostics of scaling errors and their proposed corrections, or the recent disagreement between the sunspot sumber and other solar indices like the 10.7cm radio flux. Our most recent analyses indicate that while part of this divergence may be due to a calibration drift in the SSN, it also results from an intrinsic change in the global magnetic parameters of sunspots and solar active regions, suggesting a possible transition to a new activity regime. Going beyond the SSN series, in the framework of the SOTERIA, TOSCA and SOLID projects, we produced a survey of all existing catalogs providing detailed sunspot information and we also located different primary solar images and drawing collections that can be exploitable to complement the existing catalogs (COMESEP project). These are first steps towards the construction of a multi-parametric time series of multiple sunspot group properties over at least the last 150 years, allowing to reconstruct and extend the current 1-D SSN series. By bringing new spatial, morphological and evolutionary information, such a data set should bring major advances for the modeling of the solar dynamo and solar irradiance. We will present here the current status of this work. The catalog now extends over the last 3 cycles (Lefevre & Clette 2011

Sunspot drawings handwritten character recognition method based on deep learning

Science.gov (United States)

Zheng, Sheng; Zeng, Xiangyun; Lin, Ganghua; Zhao, Cui; Feng, Yongli; Tao, Jinping; Zhu, Daoyuan; Xiong, Li

2016-05-01

High accuracy scanned sunspot drawings handwritten characters recognition is an issue of critical importance to analyze sunspots movement and store them in the database. This paper presents a robust deep learning method for scanned sunspot drawings handwritten characters recognition. The convolution neural network (CNN) is one algorithm of deep learning which is truly successful in training of multi-layer network structure. CNN is used to train recognition model of handwritten character images which are extracted from the original sunspot drawings. We demonstrate the advantages of the proposed method on sunspot drawings provided by Chinese Academy Yunnan Observatory and obtain the daily full-disc sunspot numbers and sunspot areas from the sunspot drawings. The experimental results show that the proposed method achieves a high recognition accurate rate.

MAG4 versus alternative techniques for forecasting active region flare productivity

Science.gov (United States)

Falconer, David A; Moore, Ronald L; Barghouty, Abdulnasser F; Khazanov, Igor

2014-01-01

MAG4 is a technique of forecasting an active region's rate of production of major flares in the coming few days from a free magnetic energy proxy. We present a statistical method of measuring the difference in performance between MAG4 and comparable alternative techniques that forecast an active region's major-flare productivity from alternative observed aspects of the active region. We demonstrate the method by measuring the difference in performance between the “Present MAG4” technique and each of three alternative techniques, called “McIntosh Active-Region Class,” “Total Magnetic Flux,” and “Next MAG4.” We do this by using (1) the MAG4 database of magnetograms and major flare histories of sunspot active regions, (2) the NOAA table of the major-flare productivity of each of 60 McIntosh active-region classes of sunspot active regions, and (3) five technique performance metrics (Heidke Skill Score, True Skill Score, Percent Correct, Probability of Detection, and False Alarm Rate) evaluated from 2000 random two-by-two contingency tables obtained from the databases. We find that (1) Present MAG4 far outperforms both McIntosh Active-Region Class and Total Magnetic Flux, (2) Next MAG4 significantly outperforms Present MAG4, (3) the performance of Next MAG4 is insensitive to the forward and backward temporal windows used, in the range of one to a few days, and (4) forecasting from the free-energy proxy in combination with either any broad category of McIntosh active-region classes or any Mount Wilson active-region class gives no significant performance improvement over forecasting from the free-energy proxy alone (Present MAG4). Key Points Quantitative comparison of performance of pairs of forecasting techniques Next MAG4 forecasts major flares more accurately than Present MAG4 Present MAG4 forecast outperforms McIntosh AR Class and total magnetic flux PMID:26213517

HELIOSEISMOLOGY OF A REALISTIC MAGNETOCONVECTIVE SUNSPOT SIMULATION

International Nuclear Information System (INIS)

Braun, D. C.; Birch, A. C.; Rempel, M.; Duvall, T. L. Jr.

2012-01-01

We compare helioseismic travel-time shifts measured from a realistic magnetoconvective sunspot simulation using both helioseismic holography and time-distance helioseismology, and measured from real sunspots observed with the Helioseismic and Magnetic Imager instrument on board the Solar Dynamics Observatory and the Michelson Doppler Imager instrument on board the Solar and Heliospheric Observatory. We find remarkable similarities in the travel-time shifts measured between the methodologies applied and between the simulated and real sunspots. Forward modeling of the travel-time shifts using either Born or ray approximation kernels and the sound-speed perturbations present in the simulation indicates major disagreements with the measured travel-time shifts. These findings do not substantially change with the application of a correction for the reduction of wave amplitudes in the simulated and real sunspots. Overall, our findings demonstrate the need for new methods for inferring the subsurface structure of sunspots through helioseismic inversions.

Solar irridiance variations and solar activity

International Nuclear Information System (INIS)

Willson, R.C.

1982-01-01

A mean value for the 1 AU total solar irradiance of 1368.2 W/m 2 and a downward trend of 0.05% per year were derived from measurements by the Active Cavity Radiometer Irradiance Monitor (ACRIM) experiment on the Solar Maximum Mission during 1980. Distinct temporary solar irradiance decreases associated with solar activity maxima were observed with a series of nine dips from April to October recurring at fairly regular intervals averaging 24 days. The decreases correlate inversely with sunspot area, 2800-MHz flux, and Zurich sunspot number. Dominant periods common to the irradiance and sunspot area power spectra link the irradiance decreases to sunspot flux deficit in solar active regions. Evidence of significant total irradiance modulation by facular flux excess is cited. A persistent radiative cycle of active regions consistent with the ACRIM irradiance results and the morphology of solar active regions was found. The pattern of regularly recurrent active region maxima between April and October suggests an asymmetry in solar activity generation during this period

Magnetic Properties of Solar Active Regions that Govern Large Solar Flares and Eruptions

Science.gov (United States)

Toriumi, Shin; Schrijver, Carolus J.; Harra, Louise; Hudson, Hugh S.; Nagashima, Kaori

2017-08-01

Strong flares and CMEs are often produced from active regions (ARs). In order to better understand the magnetic properties and evolutions of such ARs, we conducted statistical investigations on the SDO/HMI and AIA data of all flare events with GOES levels >M5.0 within 45 deg from the disk center for 6 years from May 2010 (from the beginning to the declining phase of solar cycle 24). Out of the total of 51 flares from 29 ARs, more than 80% have delta-sunspots and about 15% violate Hale’s polarity rule. We obtained several key findings including (1) the flare duration is linearly proportional to the separation of the flare ribbons (i.e., scale of reconnecting magnetic fields) and (2) CME-eruptive events have smaller sunspot areas. Depending on the magnetic properties, flaring ARs can be categorized into several groups, such as spot-spot, in which a highly-sheared polarity inversion line is formed between two large sunspots, and spot-satellite, where a newly-emerging flux next to a mature sunspot triggers a compact flare event. These results point to the possibility that magnetic structures of the ARs determine the characteristics of flares and CMEs. In the presentation, we will also show new results from the systematic flux emergence simulations of delta-sunspot formation and discuss the evolution processes of flaring ARs.

SPECTROPOLARIMETRICALLY ACCURATE MAGNETOHYDROSTATIC SUNSPOT MODEL FOR FORWARD MODELING IN HELIOSEISMOLOGY

Energy Technology Data Exchange (ETDEWEB)

Przybylski, D.; Shelyag, S.; Cally, P. S. [Monash Center for Astrophysics, School of Mathematical Sciences, Monash University, Clayton, Victoria 3800 (Australia)

2015-07-01

We present a technique to construct a spectropolarimetrically accurate magnetohydrostatic model of a large-scale solar magnetic field concentration, mimicking a sunspot. Using the constructed model we perform a simulation of acoustic wave propagation, conversion, and absorption in the solar interior and photosphere with the sunspot embedded into it. With the 6173 Å magnetically sensitive photospheric absorption line of neutral iron, we calculate observable quantities such as continuum intensities, Doppler velocities, as well as the full Stokes vector for the simulation at various positions at the solar disk, and analyze the influence of non-locality of radiative transport in the solar photosphere on helioseismic measurements. Bisector shapes were used to perform multi-height observations. The differences in acoustic power at different heights within the line formation region at different positions at the solar disk were simulated and characterized. An increase in acoustic power in the simulated observations of the sunspot umbra away from the solar disk center was confirmed as the slow magnetoacoustic wave.

SPECTROPOLARIMETRICALLY ACCURATE MAGNETOHYDROSTATIC SUNSPOT MODEL FOR FORWARD MODELING IN HELIOSEISMOLOGY

International Nuclear Information System (INIS)

Przybylski, D.; Shelyag, S.; Cally, P. S.

2015-01-01

We present a technique to construct a spectropolarimetrically accurate magnetohydrostatic model of a large-scale solar magnetic field concentration, mimicking a sunspot. Using the constructed model we perform a simulation of acoustic wave propagation, conversion, and absorption in the solar interior and photosphere with the sunspot embedded into it. With the 6173 Å magnetically sensitive photospheric absorption line of neutral iron, we calculate observable quantities such as continuum intensities, Doppler velocities, as well as the full Stokes vector for the simulation at various positions at the solar disk, and analyze the influence of non-locality of radiative transport in the solar photosphere on helioseismic measurements. Bisector shapes were used to perform multi-height observations. The differences in acoustic power at different heights within the line formation region at different positions at the solar disk were simulated and characterized. An increase in acoustic power in the simulated observations of the sunspot umbra away from the solar disk center was confirmed as the slow magnetoacoustic wave

Studies of kinematic elements in two multicenter sunspot groups

International Nuclear Information System (INIS)

Korobova, Z.B.

1983-01-01

Some features of kinematic elements (KE) in two multicenter sunspot groups were studied using Tashkent full-disc white light heliograms. KE and morphological elements do not reveal any relationship. A KE coincides with a unipolar or multipolar spot or with part of a spot. It may also contain an extended stream including several spots. Relation of KE to large-scale photospheric magnetic fields is less clear. The line of polarity reversal is, in most cases, the deviding line between two adjacent KE. At the same time, a KE can contain spots of both polarities. Sunspot trajectories in the leading polarity regions show the best similarity. Interactions of KE are greatly influenced by the meridional drift. (author)

The Recalibrated Sunspot Number: Impact on Solar Cycle Predictions

Science.gov (United States)

Clette, F.; Lefevre, L.

2017-12-01

Recently and for the first time since their creation, the sunspot number and group number series were entirely revisited and a first fully recalibrated version was officially released in July 2015 by the World Data Center SILSO (Brussels). Those reference long-term series are widely used as input data or as a calibration reference by various solar cycle prediction methods. Therefore, past predictions may now need to be redone using the new sunspot series, and methods already used for predicting cycle 24 will require adaptations before attempting predictions of the next cycles.In order to clarify the nature of the applied changes, we describe the different corrections applied to the sunspot and group number series, which affect extended time periods and can reach up to 40%. While some changes simply involve constant scale factors, other corrections vary with time or follow the solar cycle modulation. Depending on the prediction method and on the selected time interval, this can lead to different responses and biases. Moreover, together with the new series, standard error estimates are also progressively added to the new sunspot numbers, which may help deriving more accurate uncertainties for predicted activity indices. We conclude on the new round of recalibration that is now undertaken in the framework of a broad multi-team collaboration articulated around upcoming ISSI workshops. We outline the future corrections that can still be expected in the future, as part of a permanent upgrading process and quality control. From now on, future sunspot-based predictive models should thus be made more adaptable, and regular updates of predictions should become common practice in order to track periodic upgrades of the sunspot number series, just like it is done when using other modern solar observational series.

Towards the automatic detection and analysis of sunspot rotation

Science.gov (United States)

Brown, Daniel S.; Walker, Andrew P.

2016-10-01

Torsional rotation of sunspots have been noted by many authors over the past century. Sunspots have been observed to rotate up to the order of 200 degrees over 8-10 days, and these have often been linked with eruptive behaviour such as solar flares and coronal mass ejections. However, most studies in the literature are case studies or small-number studies which suffer from selection bias. In order to better understand sunspot rotation and its impact on the corona, unbiased large-sample statistical studies are required (including both rotating and non-rotating sunspots). While this can be done manually, a better approach is to automate the detection and analysis of rotating sunspots using robust methods with well characterised uncertainties. The SDO/HMI instrument provide long-duration, high-resolution and high-cadence continuum observations suitable for extracting a large number of examples of rotating sunspots. This presentation will outline the analysis of SDI/HMI data to determine the rotation (and non-rotation) profiles of sunspots for the complete duration of their transit across the solar disk, along with how this can be extended to automatically identify sunspots and initiate their analysis.

LOOKING FOR GRANULATION AND PERIODICITY IMPRINTS IN THE SUNSPOT TIME SERIES

Energy Technology Data Exchange (ETDEWEB)

Lopes, Ilídio [Centro Multidisciplinar de Astrofísica, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Silva, Hugo G., E-mail: ilidio.lopes@tecnico.ulisboa.pt, E-mail: hgsilva@uevora.pt [Departamento de Física, ECT, Instituto de Ciências da Terra, Universidade de Évora, Rua Romão Ramalho 59, 7002-554 Évora (Portugal)

2015-05-10

The sunspot activity is the end result of the cyclic destruction and regeneration of magnetic fields by the dynamo action. We propose a new method to analyze the daily sunspot areas data recorded since 1874. By computing the power spectral density of daily data series using the Mexican hat wavelet, we found a power spectrum with a well-defined shape, characterized by three features. The first term is the 22 yr solar magnetic cycle, estimated in our work to be 18.43 yr. The second term is related to the daily volatility of sunspots. This term is most likely produced by the turbulent motions linked to the solar granulation. The last term corresponds to a periodic source associated with the solar magnetic activity, for which the maximum power spectral density occurs at 22.67 days. This value is part of the 22–27 day periodicity region that shows an above-average intensity in the power spectra. The origin of this 22.67 day periodic process is not clearly identified, and there is a possibility that it can be produced by convective flows inside the star. The study clearly shows a north–south asymmetry. The 18.43 yr periodical source is correlated between the two hemispheres, but the 22.67 day one is not correlated. It is shown that toward the large timescales an excess occurs in the northern hemisphere, especially near the previous two periodic sources. To further investigate the 22.67 day periodicity, we made a Lomb–Scargle spectral analysis. The study suggests that this periodicity is distinct from others found nearby.

Oscillations and Waves in Sunspots

Directory of Open Access Journals (Sweden)

Elena Khomenko

2015-11-01

Full Text Available A magnetic field modifies the properties of waves in a complex way. Significant advances have been made recently in our understanding of the physics of sunspot waves with the help of high-resolution observations, analytical theories, as well as numerical simulations. We review the current ideas in the field, providing the most coherent picture of sunspot oscillations as by present understanding.

A new look at sunspot formation using theory and observations

Science.gov (United States)

Losada, I. R.; Warnecke, J.; Glogowski, K.; Roth, M.; Brandenburg, A.; Kleeorin, N.; Rogachevskii, I.

2017-10-01

Sunspots are of basic interest in the study of the Sun. Their relevance ranges from them being an activity indicator of magnetic fields to being the place where coronal mass ejections and flares erupt. They are therefore also an important ingredient of space weather. Their formation, however, is still an unresolved problem in solar physics. Observations utilize just 2D surface information near the spot, but it is debatable how to infer deep structures and properties from local helioseismology. For a long time, it was believed that flux tubes rising from the bottom of the convection zone are the origin of the bipolar sunspot structure seen on the solar surface. However, this theory has been challenged, in particular recently by new surface observation, helioseismic inversions, and numerical models of convective dynamos. In this article we discuss another theoretical approach to the formation of sunspots: the negative effective magnetic pressure instability. This is a large-scale instability, in which the total (kinetic plus magnetic) turbulent pressure can be suppressed in the presence of a weak large-scale magnetic field, leading to a converging downflow, which eventually concentrates the magnetic field within it. Numerical simulations of forced stratified turbulence have been able to produce strong super-equipartition flux concentrations, similar to sunspots at the solar surface. In this framework, sunspots would only form close to the surface due to the instability constraints on stratification and rotation. Additionally, we present some ideas from local helioseismology, where we plan to use the Hankel analysis to study the pre-emergence phase of a sunspot and to constrain its deep structure and formation mechanism.

Study of magnetic helicity injection in the active region NOAA 9236 producing multiple flare-associated coronal mass ejection events

International Nuclear Information System (INIS)

Park, Sung-Hong; Cho, Kyung-Suk; Bong, Su-Chan; Kumar, Pankaj; Kim, Yeon-Han; Park, Young-Deuk; Kusano, Kanya; Chae, Jongchul; Park, So-Young

2013-01-01

To better understand a preferred magnetic field configuration and its evolution during coronal mass ejection (CME) events, we investigated the spatial and temporal evolution of photospheric magnetic fields in the active region NOAA 9236 that produced eight flare-associated CMEs during the time period of 2000 November 23-26. The time variations of the total magnetic helicity injection rate and the total unsigned magnetic flux are determined and examined not only in the entire active region but also in some local regions such as the main sunspots and the CME-associated flaring regions using SOHO/MDI magnetogram data. As a result, we found that (1) in the sunspots, a large amount of positive (right-handed) magnetic helicity was injected during most of the examined time period, (2) in the flare region, there was a continuous injection of negative (left-handed) magnetic helicity during the entire period, accompanied by a large increase of the unsigned magnetic flux, and (3) the flaring regions were mainly composed of emerging bipoles of magnetic fragments in which magnetic field lines have substantially favorable conditions for making reconnection with large-scale, overlying, and oppositely directed magnetic field lines connecting the main sunspots. These observational findings can also be well explained by some MHD numerical simulations for CME initiation (e.g., reconnection-favored emerging flux models). We therefore conclude that reconnection-favored magnetic fields in the flaring emerging flux regions play a crucial role in producing the multiple flare-associated CMEs in NOAA 9236.

Corona magnetic field over sunspots estimated by m-wave observation

International Nuclear Information System (INIS)

Kurihara, Masahiro

1974-01-01

The shape of the magnetic field in corona was estimated from the observation of the type I storm occurred in the last decade of August, 1971. It was found from the observation with a 160 MHz interferometer at Mt. Nobeyama that at most three storm sources, which are called radio wave source, were produced. The radio wave sources were fixed above sunspots. The height of the radio wave sources was estimated to be 0.45 R from the photosphere. The sunspots under the radio wave sources can be classified to four sub-groups. Weakening of the magnetic field on the photosphere was found from the reduction of the area of some sub-group. The relation between the activity of type I storm and the intensity of the magnetic field of sunspots is qualitatively suggested. It is considered that the radio wave sources and the sunspots were connected by common magnetic force lines. The probable magnetic field in corona was presumed and is shown in a figure. An interesting point is that the direction of magnetic force lines inclined by about 30 0 outward to the vertical line to the photosphere surface. (Kato, T.)

Solar rotation and meridional motions derived from sunspot groups

International Nuclear Information System (INIS)

Tuominen, J.; Tuominen, I.; Kyroelaeinen, J.

1982-01-01

Latitudinal and longitudinal motions of sunspot groups have been studied using the positions of recurrent sunspot groups of 103 years published by Greenwich observatory. In order to avoid any limb effects, only positions close to the central meridian have been used. The data were divided into two parts: those belonging to the years around sunspot maxima and those belonging to the years around sunspot minima. Using several different criteria it was ascertained that sunspot groups show meridional motions and that their drift curves as a function of latitude are different around maxima and around minima. In addition, also the angular velocity, as a function of latitude, was found to be different around maxima and minima. (Auth.)

Sunspot Modeling: From Simplified Models to Radiative MHD Simulations

Directory of Open Access Journals (Sweden)

Rolf Schlichenmaier

2011-09-01

Full Text Available We review our current understanding of sunspots from the scales of their fine structure to their large scale (global structure including the processes of their formation and decay. Recently, sunspot models have undergone a dramatic change. In the past, several aspects of sunspot structure have been addressed by static MHD models with parametrized energy transport. Models of sunspot fine structure have been relying heavily on strong assumptions about flow and field geometry (e.g., flux-tubes, "gaps", convective rolls, which were motivated in part by the observed filamentary structure of penumbrae or the necessity of explaining the substantial energy transport required to maintain the penumbral brightness. However, none of these models could self-consistently explain all aspects of penumbral structure (energy transport, filamentation, Evershed flow. In recent years, 3D radiative MHD simulations have been advanced dramatically to the point at which models of complete sunspots with sufficient resolution to capture sunspot fine structure are feasible. Here overturning convection is the central element responsible for energy transport, filamentation leading to fine-structure and the driving of strong outflows. On the larger scale these models are also in the progress of addressing the subsurface structure of sunspots as well as sunspot formation. With this shift in modeling capabilities and the recent advances in high resolution observations, the future research will be guided by comparing observation and theory.

INTERFERENCE FRINGES OF SOLAR ACOUSTIC WAVES AROUND SUNSPOTS

Energy Technology Data Exchange (ETDEWEB)

Chou, Dean-Yi; Zhao Hui; Yang, Ming-Hsu; Liang, Zhi-Chao, E-mail: chou@phys.nthu.edu.tw [Physics Department, National Tsing Hua University, Hsinchu, Taiwan (China)

2012-10-20

Solar acoustic waves are scattered by a sunspot due to the interaction between the acoustic waves and the sunspot. The sunspot, excited by the incident wave, generates the scattered wave. The scattered wave is added to the incident wave to form the total wave around the sunspot. The interference fringes between the scattered wave and the incident wave are visible in the intensity of the total wave because the coherent time of the incident wave is of the order of a wave period. The strength of the interference fringes anti-correlates with the width of temporal spectra of the incident wave. The separation between neighboring fringes increases with the incident wavelength and the sunspot size. The strength of the fringes increases with the radial order n of the incident wave from n = 0 to n = 2, and then decreases from n = 2 to n = 5. The interference fringes play a role analogous to holograms in optics. This study suggests the feasibility of using the interference fringes to reconstruct the scattered wavefields of the sunspot, although the quality of the reconstructed wavefields is sensitive to the noise and errors in the interference fringes.

Iwahashi Zenbei's Sunspot Drawings in 1793 in Japan

Science.gov (United States)

Hayakawa, Hisashi; Iwahashi, Kiyomi; Tamazawa, Harufumi; Toriumi, Shin; Shibata, Kazunari

2018-01-01

Three Japanese sunspot drawings associated with Iwahashi Zenbei (1756 - 1811) are shown here from contemporary manuscripts and woodprint documents with the relevant texts. We reveal the observational date of one of the drawings to be 26 August 1793, and the overall observations lasted for over a year. Moreover, we identify the observational site for the dated drawing as Fushimi in Japan. We then compare Zenbei's observations with the group sunspot number and the raw group count from the Sunspot Index and Long-term Solar Observations (SILSO) to reveal the context of the data, and we conclude that these drawings fill gaps in our understanding that are due to the fragmental sunspot observations around 1793. These drawings are important as a clue to evaluate astronomical knowledge of contemporary Japan in the late eighteenth century and are valuable as a non-European observation, considering that most sunspot observations up to the middle of the nineteenth century are from Europe.

SUNSPOT CYCLES IMPACTS ON TOURISM AND QUALITY OF LIFE

Directory of Open Access Journals (Sweden)

Tadeja Jere Jakulin

2017-09-01

Full Text Available We live under the influence of natural cycles caused by the rotation of our planet and its revolution around the sun. The nature of our nearest star is also subject to cyclical change. This article presents a study of a correlation between sunspot cycles and foreign tourists arrivals in Slovenia, based on historical data between sunspot cycles and sea salt production in Slovenia's Municipality of Piran during the Maunder Minimum period (1645-1715. The production of salt by the solar evaporation of brine in salt pans and tourist industry are seasonal economic activities that are affected by changes to the weather. The paper looks at sea salt production in Piran during a particular period in the past. The repetition of the sea salt production in the past is not possible. For this reason, the study uses mathematical tools and an additional case study, which analyses arrivals of foreign tourists to Slovenia over the past 65 years (1948-2012. The study has two purposes: to identify a linear correlation coefficient, which provides evidence of a correlation between arrivals of foreign tourists to Slovenia and sunspot cycles and to develop a causal loop diagram (CLD or so called qualitative model of a complex tourism system, which shows the interdependency of sunspot cycles, tourism system, and quality of life.

Empirical mode decomposition and long-range correlation analysis of sunspot time series

International Nuclear Information System (INIS)

Zhou, Yu; Leung, Yee

2010-01-01

Sunspots, which are the best known and most variable features of the solar surface, affect our planet in many ways. The number of sunspots during a period of time is highly variable and arouses strong research interest. When multifractal detrended fluctuation analysis (MF-DFA) is employed to study the fractal properties and long-range correlation of the sunspot series, some spurious crossover points might appear because of the periodic and quasi-periodic trends in the series. However many cycles of solar activities can be reflected by the sunspot time series. The 11-year cycle is perhaps the most famous cycle of the sunspot activity. These cycles pose problems for the investigation of the scaling behavior of sunspot time series. Using different methods to handle the 11-year cycle generally creates totally different results. Using MF-DFA, Movahed and co-workers employed Fourier truncation to deal with the 11-year cycle and found that the series is long-range anti-correlated with a Hurst exponent, H, of about 0.12. However, Hu and co-workers proposed an adaptive detrending method for the MF-DFA and discovered long-range correlation characterized by H≈0.74. In an attempt to get to the bottom of the problem in the present paper, empirical mode decomposition (EMD), a data-driven adaptive method, is applied to first extract the components with different dominant frequencies. MF-DFA is then employed to study the long-range correlation of the sunspot time series under the influence of these components. On removing the effects of these periods, the natural long-range correlation of the sunspot time series can be revealed. With the removal of the 11-year cycle, a crossover point located at around 60 months is discovered to be a reasonable point separating two different time scale ranges, H≈0.72 and H≈1.49. And on removing all cycles longer than 11 years, we have H≈0.69 and H≈0.28. The three cycle-removing methods—Fourier truncation, adaptive detrending and the

LIGHT BRIDGE IN A DEVELOPING ACTIVE REGION. I. OBSERVATION OF LIGHT BRIDGE AND ITS DYNAMIC ACTIVITY PHENOMENA

International Nuclear Information System (INIS)

Toriumi, Shin; Katsukawa, Yukio; Cheung, Mark C. M.

2015-01-01

Light bridges, the bright structures that divide the umbra of sunspots and pores into smaller pieces, are known to produce a wide variety of activity events in solar active regions (ARs). It is also known that the light bridges appear in the assembling process of nascent sunspots. The ultimate goal of this series of papers is to reveal the nature of light bridges in developing ARs and the occurrence of activity events associated with the light bridge structures from both observational and numerical approaches. In this first paper, exploiting the observational data obtained by Hinode, the Interface Region Imaging Spectrograph, and the Solar Dynamics Observatory, we investigate the detailed structure of the light bridge in NOAA AR 11974 and its dynamic activity phenomena. As a result, we find that the light bridge has a weak, horizontal magnetic field, which is transported from the interior by a large-scale convective upflow and is surrounded by strong, vertical fields of adjacent pores. In the chromosphere above the bridge, a transient brightening occurs repeatedly and intermittently, followed by a recurrent dark surge ejection into higher altitudes. Our analysis indicates that the brightening is the plasma heating due to magnetic reconnection at lower altitudes, while the dark surge is the cool, dense plasma ejected from the reconnection region. From the observational results, we conclude that the dynamic activity observed in a light bridge structure such as chromospheric brightenings and dark surge ejections are driven by magnetoconvective evolution within the light bridge and its interaction with the surrounding magnetic fields

LIGHT BRIDGE IN A DEVELOPING ACTIVE REGION. I. OBSERVATION OF LIGHT BRIDGE AND ITS DYNAMIC ACTIVITY PHENOMENA

Energy Technology Data Exchange (ETDEWEB)

Toriumi, Shin; Katsukawa, Yukio [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Cheung, Mark C. M., E-mail: shin.toriumi@nao.ac.jp [Lockheed Martin Solar and Astrophysics Laboratory, 3251 Hanover Street, Building/252, Palo Alto, CA 94304 (United States)

2015-10-01

Light bridges, the bright structures that divide the umbra of sunspots and pores into smaller pieces, are known to produce a wide variety of activity events in solar active regions (ARs). It is also known that the light bridges appear in the assembling process of nascent sunspots. The ultimate goal of this series of papers is to reveal the nature of light bridges in developing ARs and the occurrence of activity events associated with the light bridge structures from both observational and numerical approaches. In this first paper, exploiting the observational data obtained by Hinode, the Interface Region Imaging Spectrograph, and the Solar Dynamics Observatory, we investigate the detailed structure of the light bridge in NOAA AR 11974 and its dynamic activity phenomena. As a result, we find that the light bridge has a weak, horizontal magnetic field, which is transported from the interior by a large-scale convective upflow and is surrounded by strong, vertical fields of adjacent pores. In the chromosphere above the bridge, a transient brightening occurs repeatedly and intermittently, followed by a recurrent dark surge ejection into higher altitudes. Our analysis indicates that the brightening is the plasma heating due to magnetic reconnection at lower altitudes, while the dark surge is the cool, dense plasma ejected from the reconnection region. From the observational results, we conclude that the dynamic activity observed in a light bridge structure such as chromospheric brightenings and dark surge ejections are driven by magnetoconvective evolution within the light bridge and its interaction with the surrounding magnetic fields.

Surge-like Oscillations above Sunspot Light Bridges Driven by Magnetoacoustic Shocks

Energy Technology Data Exchange (ETDEWEB)

Zhang, Jingwen; Tian, Hui; He, Jiansen; Wang, Linghua, E-mail: huitian@pku.edu.cn [School of Earth and Space Sciences, Peking University, 100871 Beijing (China)

2017-03-20

High-resolution observations of the solar chromosphere and transition region often reveal surge-like oscillatory activities above sunspot light bridges (LBs). These oscillations are often interpreted as intermittent plasma jets produced by quasi-periodic magnetic reconnection. We have analyzed the oscillations above an LB in a sunspot using data taken by the Interface Region Imaging Spectrograph . The chromospheric 2796 Å images show surge-like activities above the entire LB at any time, forming an oscillating wall. Within the wall we often see that the core of the Mg ii k 2796.35 Å line first experiences a large blueshift, and then gradually decreases to zero shift before increasing to a redshift of comparable magnitude. Such a behavior suggests that the oscillations are highly nonlinear and likely related to shocks. In the 1400 Å passband, which samples emission mainly from the Si iv ion, the most prominent feature is a bright oscillatory front ahead of the surges. We find a positive correlation between the acceleration and maximum velocity of the moving front, which is consistent with numerical simulations of upward propagating slow-mode shock waves. The Si iv 1402.77 Å line profile is generally enhanced and broadened in the bright front, which might be caused by turbulence generated through compression or by the shocks. These results, together with the fact that the oscillation period stays almost unchanged over a long duration, lead us to propose that the surge-like oscillations above LBs are caused by shocked p-mode waves leaked from the underlying photosphere.

Long-term periodicities in the sunspot record

International Nuclear Information System (INIS)

Wilson, R.M.

1984-07-01

Sunspot records are systematically maintained, with the knowledge that an 11 year average period exists since about 1850. Thus, the sunspot record of highest quality and considered to be the most reliable is that of cycle eight through the present. On the basis of cycles 8 through 20, various combinations of sine curves were used to approximate the observed R sub MAX values (where R sub MAX is the smoothed sunspot number at cycle maximum). It is found that a three component sinusoidal function, having an 11 cycle and a 2 cycle variation on a 90 cycle periodicity, yields computed R sub MAX values which fit, reasonably well, observed R sub MAX values for the modern sunspot cycles. Extrapolation of the empirical functions forward in time allows for the projection of values of R sub MAX for cycles 21 and 22. For cycle 21, the function projects a value of 157.3, very close to the actually observed value of 164.5. For cycle 22, the function projects a value of about 107. Linear regressions applied to cycle 22 indicate a long-period cycle (cycle duration 132 months). An extensive bibliography on techniques used to estimate the time dependent behavior of sunspot cycles is provided

Block-induced Complex Structures Building the Flare-productive Solar Active Region 12673

Energy Technology Data Exchange (ETDEWEB)

Yang, Shuhong; Zhang, Jun [CAS Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Zhu, Xiaoshuai [Max-Planck Institute for Solar System Research, D-37077 Göttingen (Germany); Song, Qiao, E-mail: shuhongyang@nao.cas.cn [Key Laboratory of Space Weather, National Center for Space Weather, China Meteorological Administration, Beijing 100081 (China)

2017-11-10

Solar active region (AR) 12673 produced 4 X-class, 27 M-class, and numerous lower-class flares during its passage across the visible solar disk in 2017 September. Our study is to answer the questions why this AR was so flare-productive and how the X9.3 flare, the largest one of the past decade, took place. We find that there was a sunspot in the initial several days, and then two bipolar regions emerged nearby it successively. Due to the standing of the pre-existing sunspot, the movement of the bipoles was blocked, while the pre-existing sunspot maintained its quasi-circular shaped umbra only with the disappearance of a part of penumbra. Thus, the bipolar patches were significantly distorted, and the opposite polarities formed two semi-circular shaped structures. After that, two sequences of new bipolar regions emerged within the narrow semi-circular zone, and the bipolar patches separated along the curved channel. The new bipoles sheared and interacted with the previous ones, forming a complex topological system, during which numerous flares occurred. At the highly sheared region, a great deal of free energy was accumulated. On September 6, one negative patch near the polarity inversion line began to rapidly rotate and shear with the surrounding positive fields, and consequently the X9.3 flare erupted. Our results reveal that the block-induced complex structures built the flare-productive AR and the X9.3 flare was triggered by an erupting filament due to the kink instability. To better illustrate this process, a block-induced eruption model is proposed for the first time.

Historical evidence concerning the Sun: interpretation of sunspot records during the telescopic and pretelescopic eras

International Nuclear Information System (INIS)

Stephenson, F.R.

1990-01-01

The value of sunspot observations in investigating solar activity trends - mainly on the centennial to millennial timescale - is considered in some detail. It is shown that although observations made since the mid-eighteenth century are in general very reliable indicators of solar activity, older data are of dubious quality and utility. The sunspot record in both the pretelescopic and early telescopic periods appears to be confused by serious data artefacts. (author)

MEASUREMENTS OF ABSORPTION, EMISSIVITY REDUCTION, AND LOCAL SUPPRESSION OF SOLAR ACOUSTIC WAVES IN SUNSPOTS

International Nuclear Information System (INIS)

Chou, D.-Y.; Liang, Z.-C.; Yang, M.-H.; Zhao Hui; Sun, M.-T.

2009-01-01

The power of solar acoustic waves in magnetic regions is lower relative to the quiet Sun. Absorption, emissivity reduction, and local suppression of acoustic waves contribute to the observed power reduction in magnetic regions. We propose a model for the energy budget of acoustic waves propagating through a sunspot in terms of the coefficients of absorption, emissivity reduction, and local suppression of the sunspot. Using the property that the waves emitted along the wave path between two points have no correlation with the signal at the starting point, we can separate the effects of these three mechanisms. Applying this method to helioseismic data filtered with direction and phase-velocity filters, we measure the fraction of the contribution of each mechanism to the power deficit in the umbra of the leading sunspot of NOAA 9057. The contribution from absorption is 23.3 ± 1.3%, emissivity reduction 8.2 ± 1.4%, and local suppression 68.5 ± 1.5%, for a wave packet corresponding to a phase velocity of 6.98 x 10 -5 rad s -1 .

Steady flows in the chromosphere and transition-zone above active regions as observed by OSO-8

Science.gov (United States)

Lites, B. W.

1980-01-01

Two years of data from the University of Colorado ultraviolet spectrometer aboard OSO-8 were searched for steady line-of-sight flows in the chromosphere and transition-zone above active regions. The most conspicuous pattern that emerges from this data set is that many sunspots show persistent blueshifts of transition-zone lines indicating velocities of about 20 km/s with respect to the surrounding plage areas. The data show much smaller shifts in ultraviolet emission lines arising from the chromosphere: the shifts are frequently to the blue, but sometimes redshifts do occur. Plage areas often show a redshift of the transition-zone lines relative to the surrounding quiet areas, and a strong gradient of the vertical component of the velocity is evident in many plages. One area of persistent blueshift was observed in the transition-zone above an active region filament. The energy requirement of these steady flows over sunspots is discussed.

A steady-state supersonic downflow in the transition region above a sunspot umbra

Science.gov (United States)

Straus, Thomas; Fleck, Bernhard; Andretta, Vincenzo

2015-10-01

We investigate a small-scale (~1.5 Mm along the slit), supersonic downflow of about 90 km s-1 in the transition region above the lightbridged sunspot umbra in AR 11836. The observations were obtained with the Interface Region Spectrograph (IRIS) on 2013 September 2 from 16:40 to 17:59 UT. The downflow shows up as redshifted "satellite" lines of the Si iv and O iv transition region lines and is remarkably steady over the observing period of nearly 80 min. The downflow is not visible in the chromospheric lines, which only show an intensity enhancement at the location of the downflow. The density inferred from the line ratio of the redshifted satellites of the O iv lines (Ne = 1010.6 ± 0.25 cm-3) is only a factor 2 smaller than the one inferred from the main components (Ne = 1010.95 ± 0.20 cm-3). Consequently, this implies a substantial mass flux (~5 × 10-7 g cm-2 s-1), which would evacuate the overlying corona on timescales close to 10 s. We interpret these findings as evidence of a stationary termination shock of a supersonic siphon flow in a cool loop that is rooted in the central umbra of the spot. The movie is available in electronic form at http://www.aanda.org

HELIOSEISMIC HOLOGRAPHY OF SIMULATED SUNSPOTS: MAGNETIC AND THERMAL CONTRIBUTIONS TO TRAVEL TIMES

Energy Technology Data Exchange (ETDEWEB)

Felipe, T. [Departamento de Astrofísica, Universidad de La Laguna, E-38205 La Laguna, Tenerife (Spain); Braun, D. C.; Crouch, A. D. [NorthWest Research Associates, Colorado Research Associates, Boulder, CO 80301 (United States); Birch, A. C., E-mail: tobias@iac.es [Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany)

2016-10-01

Wave propagation through sunspots involves conversion between waves of acoustic and magnetic character. In addition, the thermal structure of sunspots is very different than that of the quiet Sun. As a consequence, the interpretation of local helioseismic measurements of sunspots has long been a challenge. With the aim of understanding these measurements, we carry out numerical simulations of wave propagation through sunspots. Helioseismic holography measurements made from the resulting simulated wavefields show qualitative agreement with observations of real sunspots. We use additional numerical experiments to determine, separately, the influence of the thermal structure of the sunspot and the direct effect of the sunspot magnetic field. We use the ray approximation to show that the travel-time shifts in the thermal (non-magnetic) sunspot model are primarily produced by changes in the wave path due to the Wilson depression rather than variations in the wave speed. This shows that inversions for the subsurface structure of sunspots must account for local changes in the density. In some ranges of horizontal phase speed and frequency there is agreement (within the noise level in the simulations) between the travel times measured in the full magnetic sunspot model and the thermal model. If this conclusion proves to be robust for a wide range of models, it would suggest a path toward inversions for sunspot structure.

HELIOSEISMIC HOLOGRAPHY OF SIMULATED SUNSPOTS: MAGNETIC AND THERMAL CONTRIBUTIONS TO TRAVEL TIMES

International Nuclear Information System (INIS)

Felipe, T.; Braun, D. C.; Crouch, A. D.; Birch, A. C.

2016-01-01

Wave propagation through sunspots involves conversion between waves of acoustic and magnetic character. In addition, the thermal structure of sunspots is very different than that of the quiet Sun. As a consequence, the interpretation of local helioseismic measurements of sunspots has long been a challenge. With the aim of understanding these measurements, we carry out numerical simulations of wave propagation through sunspots. Helioseismic holography measurements made from the resulting simulated wavefields show qualitative agreement with observations of real sunspots. We use additional numerical experiments to determine, separately, the influence of the thermal structure of the sunspot and the direct effect of the sunspot magnetic field. We use the ray approximation to show that the travel-time shifts in the thermal (non-magnetic) sunspot model are primarily produced by changes in the wave path due to the Wilson depression rather than variations in the wave speed. This shows that inversions for the subsurface structure of sunspots must account for local changes in the density. In some ranges of horizontal phase speed and frequency there is agreement (within the noise level in the simulations) between the travel times measured in the full magnetic sunspot model and the thermal model. If this conclusion proves to be robust for a wide range of models, it would suggest a path toward inversions for sunspot structure.

An essay on sunspots and solar flares

International Nuclear Information System (INIS)

Akasofu, S.-I.

1984-01-01

The presently prevailing theories of sunspots and solar flares rely on the hypothetical presence of magnetic flux tubes beneath the photosphere and the two subsequent hypotheses, their emergence above the photosphere and explosive magnetic reconnection, converting magnetic energy carried by the flux tubes for solar flare energy. In this paper, attention is paid to the fact that there are large-scale magnetic fields which divide the photosphere into positive and negative (line-of-sight) polarity regions and that they are likely to be more fundamental than sunspot fields, as emphasized most recently by McIntosh. A new phenomenological model of the sunspot pair formation is then constructed by considering an amplification process of these large-scale fields near their boundaries by shear flows, including localized vortex motions. The amplification results from a dynamo process associated with such vortex flows and the associated convergence flow in the large-scale fields. This dynamo process generates also some of the familiar ''force-free'' fields or the ''sheared'' magnetic fields in which the magnetic field-aligned currents are essential. Upward field-aligned currents generated by the dynamo process are carried by downward streaming electrons which are expected to be accelerated by an electric potential structure; a similar structure is responsible for accelerating auroral electrons in the magnetosphere. Depending on the magnetic field configuration and the shear flows, the current-carrying electrons precipitate into different geometrical patterns, causing circular flares, umbral flares, two-ribbon flares, etc. Thus, it is suggested that ''low temperature flares'' are directly driven by the photospheric dynamo process. (author)

Improvement of the photometric sunspot index and changes of the disk-integrated sunspot contrast with time

Science.gov (United States)

Froehlich, Claus; Pap, Judit M.; Hudson, Hugh S.

1994-06-01

The photometric sunspot index (PSI) was developed to study the effects of sunspots on solar irradiance. It is calculated from the sunspot data published in the Solar-Geophysical Data catalog. It has been shown that the former PSI models overestimate the effect of dark sunspots on solar irradiance; furthermore results of direct sunspot photometry indicate that the contrast of spots depends on their area. An improved PSI calculation is presented; it takes into account the area dependence of the contrast and calculates `true' daily means for each observation using the differential rotation of the spots. Moreover, the observations are screened for outliers which improves the homogeneity of the data set substantially, at least for the period after December 1981 when NOAA started to report data from a few instead of one to two stations. A detailed description of the method is provided. The correlation between the newly calculated PSI and total solar irradiance is studied for different phases of the solar cycles 21 and 22 using bi-variate spectral analysis. The results can be used as a `calibration' of PSI in terms of gain, the factor by which PSI has to be multiplied to yield the observed irradiance change. The factor changes with time from about 0.6 in 1980 to 1.1 in 1990. This unexpected result cannot be interpreted by a change of the contrast relative to the quiet Sun (as it is normally defined and determined by direct photometry) but rather as a change of the contrast between the spots and their surrounding as seen in total irradiance (integrated over the solar disk). This may partly be explained by a change in the ratio between the areas of the spots and the surrounding faculae.

The sunspot cycle revisited

International Nuclear Information System (INIS)

Lomb, Nick

2013-01-01

The set of sunspot numbers observed since the invention of the telescope is one of the most studied time series in astronomy and yet it is also one of the most complex. Fourteen frequencies are found in the yearly mean sunspot numbers from 1700 to 2011using the Lomb-Scargle periodogram and prewhitening. All of the frequencies corresponding to shorter term periods can be matched with simple algebraic combinations of the frequency of the main 11-year period and the frequencies of the longer term periods in the periodogram. This is exactly what can be expected from amplitude and phase modulation of an 11.12-year periodicity by longer term variations. Similar, though not identical, results are obtained after correcting the sunspot number series as proposed by Svalgaard. On looking separately at the amplitude and phase modulation a clear relationship is found between the two modulations although this relationship has broken down for the last four solar cycles. The phase modulation implies that there is a definite underlying period for the solar cycle. Such a clock mechanism does seem to be a possibility in models of the solar dynamo incorporating a conveyor-belt-like meridional circulation between high polar latitudes and the equator.

High Velocity Horizontal Motions at the Edge of Sunspot Penumbrae

Science.gov (United States)

Hagenaar-Daggett, Hermance J.; Shine, R.

2010-05-01

The outer edges of sunspot penumbrae have long been noted as a region of interesting dynamics including formation of MMFs, extensions and retractions of the penumbral tips, fast moving (2-3 km/s) bright features dubbed"streakers", and localized regions of high speed downflows interpreted as Evershed "sinks". Using 30s cadence movies of high spatial resolution G band and Ca II H images taken by the Hinode SOT/FPP instrument from 5-7 Jan 2007, we have been investigating the penumbra around a sunspot in AR 10933. In addition to the expected phenomena, we also see occasional small dark crescent-shaped features with high horizontal velocities (6.5 km/s) in G band movies. These appear to be emitted from penumbral tips. They travel about 1.5 Mm developing a bright wake that evolves into a slower moving (1-2 km/s) bright feature. In some cases, there may be an earlier outward propagating disturbance within the penumbra. We have also analyzed available Fe 6302 Stokes V images to obtain information on the magnetic field. Although only lower resolution 6302 images made with a slower cadence are available for these particular data sets, we can establish that the features have the opposite magnetic polarity of the sunspot. This observation may be in agreement with simulations showing that a horizontal flux tube develops crests that move outward with a velocity as large as 10 km/s. This work was supported by NASA contract NNM07AA01C.

Complex active regions as the main source of extreme and large solar proton events

Science.gov (United States)

Ishkov, V. N.

2013-12-01

A study of solar proton sources indicated that solar flare events responsible for ≥2000 pfu proton fluxes mostly occur in complex active regions (CARs), i.e., in transition structures between active regions and activity complexes. Different classes of similar structures and their relation to solar proton events (SPEs) and evolution, depending on the origination conditions, are considered. Arguments in favor of the fact that sunspot groups with extreme dimensions are CARs are presented. An analysis of the flare activity in a CAR resulted in the detection of "physical" boundaries, which separate magnetic structures of the same polarity and are responsible for the independent development of each structure.

Predicting Maximum Sunspot Number in Solar Cycle 24 Nipa J Bhatt ...

Indian Academy of Sciences (India)

Key words. Sunspot number—precursor prediction technique—geo- magnetic activity index aa. 1. Introduction. Predictions of solar and geomagnetic activities are important for various purposes, including the operation of low-earth orbiting satellites, operation of power grids on. Earth, and satellite communication systems.

A Standard Law for the Equatorward Drift of the Sunspot Zones

Science.gov (United States)

Hathaway, David H.

2012-01-01

The latitudinal location of the sunspot zones in each hemisphere is determined by calculating the centroid position of sunspot areas for each solar rotation from May 1874 to June 2012. When these centroid positions are plotted and analyzed as functions of time from each sunspot cycle maximum there appears to be systematic differences in the positions and equatorward drift rates as a function of sunspot cycle amplitude. If, instead, these centroid positions are plotted and analyzed as functions of time from each sunspot cycle minimum then most of the differences in the positions and equatorward drift rates disappear. The differences that remain disappear entirely if curve fitting is used to determine the starting times (which vary by as much as 8 months from the times of minima). The sunspot zone latitudes and equatorward drift measured relative to this starting time follow a standard path for all cycles with no dependence upon cycle strength or hemispheric dominance. Although Cycle 23 was peculiar in its length and the strength of the polar fields it produced, it too shows no significant variation from this standard. This standard law, and the lack of variation with sunspot cycle characteristics, is consistent with Dynamo Wave mechanisms but not consistent with current Flux Transport Dynamo models for the equatorward drift of the sunspot zones.

Wings of the butterfly: Sunspot groups for 1826-2015

Science.gov (United States)

Leussu, R.; Usoskin, I. G.; Senthamizh Pavai, V.; Diercke, A.; Arlt, R.; Denker, C.; Mursula, K.

2017-03-01

The spatio-temporal evolution of sunspot activity, the so-called Maunder butterfly diagram, has been continously available since 1874 using data from the Royal Greenwich Observatory, extended by SOON network data after 1976. Here we present a new extended butterfly diagram of sunspot group occurrence since 1826, using the recently digitized data from Schwabe (1826-1867) and Spörer (1866-1880). The wings of the diagram are separated using a recently developed method based on an analysis of long gaps in sunspot group occurrence in different latitude bands. We define characteristic latitudes, corresponding to the start, end, and the largest extent of the wings (the F, L, and H latitudes). The H latitudes (30°-45°) are highly significantly correlated with the strength of the wings (quantified by the total sum of the monthly numbers of sunspot groups). The F latitudes (20°-30°) depict a weak tendency, especially in the southern hemisphere, to follow the wing strength. The L latitudes (2°-10°) show no clear relation to the wing strength. Overall, stronger cycle wings tend to start at higher latitudes and have a greater wing extent. A strong (5-6)-cycle periodic oscillation is found in the start and end times of the wings and in the overlap and gaps between successive wings of one hemisphere. While the average wing overlap is zero in the southern hemisphere, it is two to three months in the north. A marginally significant oscillation of about ten solar cycles is found in the asymmetry of the L latitudes. The new long database of butterfly wings provides new observational constraints to solar dynamo models that discuss the spatio-temporal distribution of sunspot occurrence over the solar cycle and longer. Digital data for Fig. 1 are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/599/A131

Long-term Modulation of Cosmic Ray Intensity in relation to Sunspot ...

Indian Academy of Sciences (India)

it should be more closely connected with cosmic ray modulation than with other solar characteristics (sunspot numbers or coronal emission intensity). The intensity of galactic cosmic rays varies inversely with sunspot numbers, having their maximum intensity at the minimum of the 11-year sunspot cycle (Forbush 1954, 1958) ...

Aurorae, sunspots and weather, mainly since A.D. 1200

International Nuclear Information System (INIS)

Schove, D.J.

1981-01-01

Auroral records recieved for the Spectrum of Time project were used in 1955 to estimate sunspot activity and the dates maxima and minima back to 649 B.C. An additional set of rules has been developed and has made possible further improvements utilizing the separate auroral maxima associated with flares and coronal holes on the sun. A further set can now be given. 1) The time between sunspot maxima depends especially on the ratio of the amplitudes: the time between minima is high if the next cycle is very weak and low when the two consecutive cycles are both strong. 2) The time of rise is usually dependent on the strength of the next maxima, and the time of fall is low when a moderate cycle is followed by a strong one. (orig./WL)

Solar magnetic field studies using the 12 micron emission lines. II - Stokes profiles and vector field samples in sunspots

Science.gov (United States)

Hewagama, Tilak; Deming, Drake; Jennings, Donald E.; Osherovich, Vladimir; Wiedemann, Gunter; Zipoy, David; Mickey, Donald L.; Garcia, Howard

1993-01-01

Polarimetric observations at 12 microns of two sunpots are reported. The horizontal distribution of parameters such as magnetic field strength, inclination, azimuth, and magnetic field filling factors are presented along with information about the height dependence of the magnetic field strength. Comparisons with contemporary magnetostatic sunspot models are made. The magnetic data are used to estimate the height of 12 micron line formation. From the data, it is concluded that within a stable sunspot there are no regions that are magnetically filamentary, in the sense of containing both strong-field and field-free regions.

SOHO sees right through the Sun, and finds sunspots on the far side

Science.gov (United States)

2000-03-01

front side about 6 seconds earlier than equivalent waves from sunspot-free regions, in a total travel time of about 3 hours. The change in speed becomes evident when sound waves shuttling back and forth get out of step with one another. MDI data for 28-29 March 1998 revealed, on the far side, a sunspot group that was not plainly visible on the near side until ten days later. Observations for 24 hours were more than sufficient to detect the sunspots, which means that routine monitoring is a realistic possibility. "The far-side sunspots are a good example of why this spacecraft is so exciting to work with," said Bernhard Fleck, ESA's project scientist for SOHO. "We can make a completely new discovery in fundamental solar physics, and immediately think of applying it to the practical task of monitoring the daily activity of the Sun and predicting its effects on the Earth." The SOHO project is an international cooperation between the European Space Agency (ESA) and NASA. The spacecraft was built in Europe for ESA and equipped with instruments by teams of scientists in Europe and the USA. NASA launched SOHO in December 1995, and in 1998 ESA and NASA decided to extend its highly successful operations until 2003.

SEISMIC DISCRIMINATION OF THERMAL AND MAGNETIC ANOMALIES IN SUNSPOT UMBRAE

International Nuclear Information System (INIS)

Lindsey, C.; Cally, P. S.; Rempel, M.

2010-01-01

Efforts to model sunspots based on helioseismic signatures need to discriminate between the effects of (1) a strong magnetic field that introduces time-irreversible, vantage-dependent phase shifts, apparently connected to fast- and slow-mode coupling and wave absorption and (2) a thermal anomaly that includes cool gas extending an indefinite depth beneath the photosphere. Helioseismic observations of sunspots show travel times considerably reduced with respect to equivalent quiet-Sun signatures. Simulations by Moradi and Cally of waves skipping across sunspots with photospheric magnetic fields of order 3 kG show travel times that respond strongly to the magnetic field and relatively weakly to the thermal anomaly by itself. We note that waves propagating vertically in a vertical magnetic field are relatively insensitive to the magnetic field, while remaining highly responsive to the attendant thermal anomaly. Travel-time measurements for waves with large skip distances into the centers of axially symmetric sunspots are therefore a crucial resource for discrimination of the thermal anomaly beneath sunspot umbrae from the magnetic anomaly. One-dimensional models of sunspot umbrae based on compressible-radiative-magnetic-convective simulations such as by Rempel et al. can be fashioned to fit observed helioseismic travel-time spectra in the centers of sunspot umbrae. These models are based on cooling of the upper 2-4 Mm of the umbral subphotosphere with no significant anomaly beneath 4.5 Mm. The travel-time reductions characteristic of these models are primarily a consequence of a Wilson depression resulting from a strong downward buoyancy of the cooled umbral medium.

SOLAR VARIABILITY FROM 240 TO 1750 nm IN TERMS OF FACULAE BRIGHTENING AND SUNSPOT DARKENING FROM SCIAMACHY

International Nuclear Information System (INIS)

Pagaran, J.; Weber, M.; Burrows, J.

2009-01-01

The change of spectral decomposition of the total radiative output on various timescales of solar magnetic activity is of large interest to terrestrial and solar-stellar atmosphere studies. Starting in 2002, SCIAMACHY was the first satellite instrument to observe daily solar spectral irradiance (SSI) continuously from 230 nm (UV) to 1750 nm (near-infrared; near-IR). In order to address the question of how much UV, visible (vis), and IR spectral regions change on 27 day and 11 year timescales, we parameterize short-term SSI variations in terms of faculae brightening (Mg II index) and sunspot darkening (photometric sunspot index) proxies. Although spectral variations above 300 nm are below 1% and, therefore, well below the accuracy of absolute radiometric calibration, relative accuracy for short-term changes is shown to be in the per mill range. This enables us to derive short-term spectral irradiance variations from the UV to the near-IR. During Halloween solar storm in 2003 with a record high sunspot area, we observe a reduction of 0.3% in the near-IR to 0.5% in the vis and near-UV. This is consistent with a 0.4% reduction in total solar irradiance (TSI). Over an entire 11 year solar cycle, SSI variability covering simultaneously the UV, vis, and IR spectral regions have not been directly observed so far. Using variations of solar proxies over solar cycle 23, solar cycle spectral variations have been estimated using scaling factors that best matched short-term variations of SCIAMACHY. In the 300-400 nm region, which strongly contributes to TSI solar cycle change, a contribution of 34% is derived from SCIAMACHY observations, which is lower than the reported values from SUSIM satellite data and the empirical SATIRE model. The total UV contribution (below 400 nm) to TSI solar cycle variations is estimated to be 55%.

THE 'MAIN SEQUENCE' OF EXPLOSIVE SOLAR ACTIVE REGIONS: DISCOVERY AND INTERPRETATION

Energy Technology Data Exchange (ETDEWEB)

Falconer, David A; Moore, Ronald L; Adams, Mitzi [Space Science Office, VP62, Marshall Space Flight Center, Huntsville, AL 35812 (United States); Gary, G. Allen [Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, Huntsville, AL 35899 (United States)], E-mail: David.falconer@msfc.nasa.gov

2009-08-01

We examine the location and distribution of the production of coronal mass ejections (CMEs) and major flares by sunspot active regions in the phase space of two whole-active-region magnetic quantities measured from 1897 SOHO/MDI magnetograms. These magnetograms track the evolution of 44 active regions across the central disk of radius 0.5 R {sub Sun}. The two quantities are {sup L}WL{sub SG}, a gauge of the total free energy in an active region's magnetic field, and {sup L}{phi}, a measure of the active region's total magnetic flux. From these data and each active region's history of production of CMEs, X flares, and M flares, we find (1) that CME/flare-productive active regions are concentrated in a straight-line 'main sequence' in (log {sup L}WL{sub SG}, log {sup L}{phi}) space, (2) that main-sequence active regions have nearly their maximum attainable free magnetic energy, and (3) evidence that this arrangement plausibly results from equilibrium between input of free energy to an explosive active region's magnetic field in the chromosphere and corona by contortion of the field via convection in and below the photosphere and loss of free energy via CMEs, flares, and coronal heating, an equilibrium between energy gain and loss that is analogous to that of the main sequence of hydrogen-burning stars in (mass, luminosity) space.

THE 'MAIN SEQUENCE' OF EXPLOSIVE SOLAR ACTIVE REGIONS: DISCOVERY AND INTERPRETATION

International Nuclear Information System (INIS)

Falconer, David A.; Moore, Ronald L.; Adams, Mitzi; Gary, G. Allen

2009-01-01

We examine the location and distribution of the production of coronal mass ejections (CMEs) and major flares by sunspot active regions in the phase space of two whole-active-region magnetic quantities measured from 1897 SOHO/MDI magnetograms. These magnetograms track the evolution of 44 active regions across the central disk of radius 0.5 R Sun . The two quantities are L WL SG , a gauge of the total free energy in an active region's magnetic field, and L Φ, a measure of the active region's total magnetic flux. From these data and each active region's history of production of CMEs, X flares, and M flares, we find (1) that CME/flare-productive active regions are concentrated in a straight-line 'main sequence' in (log L WL SG , log L Φ) space, (2) that main-sequence active regions have nearly their maximum attainable free magnetic energy, and (3) evidence that this arrangement plausibly results from equilibrium between input of free energy to an explosive active region's magnetic field in the chromosphere and corona by contortion of the field via convection in and below the photosphere and loss of free energy via CMEs, flares, and coronal heating, an equilibrium between energy gain and loss that is analogous to that of the main sequence of hydrogen-burning stars in (mass, luminosity) space.

A Test of the Active-Day Fraction Method of Sunspot Group Number Calibration: Dependence on the Level of Solar Activity

Science.gov (United States)

Willamo, T.; Usoskin, I. G.; Kovaltsov, G. A.

2018-04-01

The method of active-day fraction (ADF) was proposed recently to calibrate different solar observers to standard observational conditions. The result of the calibration may depend on the overall level of solar activity during the observational period. This dependency is studied quantitatively using data of the Royal Greenwich Observatory by formally calibrating synthetic pseudo-observers to the full reference dataset. It is shown that the sunspot group number is precisely estimated by the ADF method for periods of moderate activity, may be slightly underestimated by 0.5 - 1.5 groups ({≤} 10%) for strong and very strong activity, and is strongly overestimated by up to 2.5 groups ({≤} 30%) for weak-to-moderate activity. The ADF method becomes inapplicable for the periods of grand minima of activity. In general, the ADF method tends to overestimate the overall level of activity and to reduce the long-term trends.

Molecular Diagnostics of the Internal Structure of Starspots and Sunspots

Science.gov (United States)

Afram, N.; Berdyugina, S. V.; Fluri, D. M.; Solanki, S. K.; Lagg, A.; Petit, P.; Arnaud, J.

2006-12-01

We have analyzed the usefulness of molecules as a diagnostic tool for studying solar and stellar magnetism with the molecular Zeeman and Paschen-Back effects. In the first part we concentrate on molecules that are observed in sunspots such as MgH and TiO. We present calculated molecular line profiles obtained by assuming magnetic fields of 2-3 kG and compare these synthetic Stokes profiles with spectro-polarimetric observations in sunspots. The good agreement between the theory and observations allows us to turn our attention in the second part to starspots to gain insight into their internal structure. We investigate the temperature range in which the selected molecules can serve as indicators for magnetic fields on highly active cool stars and compare synthetic Stokes profiles with our recent observations.

Flare activity, sunspot motions, and the evolution of vector magnetic fields in Hale region 17244

Science.gov (United States)

Neidig, Donald F.; Hagyard, Mona J.; Machado, Marcos E.; Smith, Jesse B., Jr.

1986-01-01

The magnetic and dynamical circumstances leading to the 1B/M4 flare of November 5, 1980 are studied, and a strong association is found between the buildup of magnetic shear and the onset of flare activity within the active region. The development of shear, as observed directly in vector magnetograms, is consistent in detail with the dynamical history of the active region and identifies the precise location of the optical and hard-X-ray kernels of the flare emission.

MULTI-WAVELENGTH STUDY OF A DELTA-SPOT. I. A REGION OF VERY STRONG, HORIZONTAL MAGNETIC FIELD

Energy Technology Data Exchange (ETDEWEB)

Jaeggli, S. A., E-mail: sarah.jaeggli@nasa.gov [NASA Goddard Space Flight Center, Solar Physics Laboratory, Code 671, Greenbelt, MD 20771 (United States)

2016-02-10

Active region NOAA 11035 appeared in 2009 December, early in the new solar activity cycle. This region achieved a delta sunspot (δ spot) configuration when parasitic flux emerged near the rotationally leading magnetic polarity and traveled through the penumbra of the largest sunspot in the group. Both visible and infrared imaging spectropolarimetry of the magnetically sensitive Fe i line pairs at 6302 and 15650 Å show large Zeeman splitting in the penumbra between the parasitic umbra and the main sunspot umbra. The polarized Stokes spectra in the strongest field region display anomalous profiles, and strong blueshifts are seen in an adjacent region. Analysis of the profiles is carried out using a Milne–Eddington inversion code capable of fitting either a single magnetic component with stray light or two independent magnetic components to verify the field strength. The inversion results show that the anomalous profiles cannot be produced by the combination of two profiles with moderate magnetic fields. The largest field strengths are 3500–3800 G in close proximity to blueshifts as strong as 3.8 km s{sup −1}. The strong, nearly horizontal magnetic field seen near the polarity inversion line in this region is difficult to understand in the context of a standard model of sunspot magnetohydrostatic equilibrium.

MULTI-WAVELENGTH STUDY OF A DELTA-SPOT. I. A REGION OF VERY STRONG, HORIZONTAL MAGNETIC FIELD

International Nuclear Information System (INIS)

Jaeggli, S. A.

2016-01-01

Active region NOAA 11035 appeared in 2009 December, early in the new solar activity cycle. This region achieved a delta sunspot (δ spot) configuration when parasitic flux emerged near the rotationally leading magnetic polarity and traveled through the penumbra of the largest sunspot in the group. Both visible and infrared imaging spectropolarimetry of the magnetically sensitive Fe i line pairs at 6302 and 15650 Å show large Zeeman splitting in the penumbra between the parasitic umbra and the main sunspot umbra. The polarized Stokes spectra in the strongest field region display anomalous profiles, and strong blueshifts are seen in an adjacent region. Analysis of the profiles is carried out using a Milne–Eddington inversion code capable of fitting either a single magnetic component with stray light or two independent magnetic components to verify the field strength. The inversion results show that the anomalous profiles cannot be produced by the combination of two profiles with moderate magnetic fields. The largest field strengths are 3500–3800 G in close proximity to blueshifts as strong as 3.8 km s −1 . The strong, nearly horizontal magnetic field seen near the polarity inversion line in this region is difficult to understand in the context of a standard model of sunspot magnetohydrostatic equilibrium

Dynamic Precursors of Flares in Active Region NOAA 10486

Science.gov (United States)

Korsós, M. B.; Gyenge, N.; Baranyi, T.; Ludmány, A.

2015-03-01

Four different methods are applied here to study the precursors of flare activity in the Active Region NOAA 10486. Two approaches track the temporal behaviour of suitably chosen features (one, the weighted hori- zontal gradient W G M , is the generalized form of the horizontal gradient of the magnetic field, G M ; the other is the sum of the horizontal gradient of the magnetic field, G S , for all sunspot pairs). W G M is a photospheric indicator, that is a proxy measure of magnetic non-potentiality of a specific area of the active region, i.e., it captures the temporal variation of the weighted horizontal gradient of magnetic flux summed up for the region where opposite magnetic polarities are highly mixed. The third one, referred to as the separateness parameter, S l- f , considers the overall morphology. Further, G S and S l- f are photospheric, newly defined quick-look indicators of the polarity mix of the entire active region. The fourth method is tracking the temporal variation of small X-ray flares, their times of succession and their energies observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager instrument. All approaches yield specific pre-cursory signatures for the imminence of flares.

Physics of the Solar Active Regions from Radio Observations

Science.gov (United States)

Gelfreikh, G. B.

1999-12-01

Localized increase of the magnetic field observed by routine methods on the photosphere result in the growth of a number of active processes in the solar atmosphere and the heliosphere. These localized regions of increased magnetic field are called active regions (AR). The main processes of transfer, accumulation and release of energy in an AR is, however, out of scope of photospheric observations being essentially a 3D-process and happening either under photosphere or up in the corona. So, to investigate these plasma structures and processes we are bound to use either extrapolation of optical observational methods or observations in EUV, X-rays and radio. In this review, we stress and illustrate the input to the problem gained from radio astronomical methods and discuss possible future development of their applicatications. Historically speaking each new step in developing radio technique of observations resulted in detecting some new physics of ARs. The most significant progress in the last few years in radio diagnostics of the plasma structures of magnetospheres of the solar ARs is connected with the developing of the 2D full disk analysis on regular basis made at Nobeyama and detailed multichannel spectral-polarization (but one-dimensional and one per day) solar observations at the RATAN-600. In this report the bulk of attention is paid to the new approach to the study of solar activity gained with the Nobeyama radioheliograph and analyzing the ways for future progress. The most important new features of the multicomponent radio sources of the ARs studied using Nobeyama radioheliograph are as follow: 1. The analysis of magnetic field structures in solar corona above sunspot with 2000 G. Their temporal evolution and fluctuations with the periods around 3 and 5 minutes, due to MHD-waves in sunspot magnetic tubes and surrounding plasma. These investigations are certainly based on an analysis of thermal cyclotron emission of lower corona and CCTR above sunspot

The EUV Spectrum of Sunspot Plumes Observed by SUMER on ...

Indian Academy of Sciences (India)

tribpo

Abstract. We present results from sunspot observations obtained by. SUMER on SOHO. In sunspot plumes the EUV spectrum differs from the quiet Sun; continua are observed with different slopes and intensities; emission lines from molecular hydrogen and many unidentified species indicate unique plasma conditions ...

MAGNETIC PROPERTIES OF SOLAR ACTIVE REGIONS THAT GOVERN LARGE SOLAR FLARES AND ERUPTIONS

Energy Technology Data Exchange (ETDEWEB)

Toriumi, Shin [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Schrijver, Carolus J. [Lockheed Martin Advanced Technology Center, 3251 Hanover Street, Palo Alto, CA 94304 (United States); Harra, Louise K. [UCL-Mullard Space Science Laboratory, Holmbury St Mary, Dorking, Surrey, RH5 6NT (United Kingdom); Hudson, Hugh [SUPA School of Physics and Astronomy, University of Glasgow (United Kingdom); Nagashima, Kaori, E-mail: shin.toriumi@nao.ac.jp [Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany)

2017-01-01

Solar flares and coronal mass ejections (CMEs), especially the larger ones, emanate from active regions (ARs). With the aim of understanding the magnetic properties that govern such flares and eruptions, we systematically survey all flare events with Geostationary Orbiting Environmental Satellite levels of ≥M5.0 within 45° from disk center between 2010 May and 2016 April. These criteria lead to a total of 51 flares from 29 ARs, for which we analyze the observational data obtained by the Solar Dynamics Observatory . More than 80% of the 29 ARs are found to exhibit δ -sunspots, and at least three ARs violate Hale’s polarity rule. The flare durations are approximately proportional to the distance between the two flare ribbons, to the total magnetic flux inside the ribbons, and to the ribbon area. From our study, one of the parameters that clearly determine whether a given flare event is CME-eruptive or not is the ribbon area normalized by the sunspot area, which may indicate that the structural relationship between the flaring region and the entire AR controls CME productivity. AR characterization shows that even X-class events do not require δ -sunspots or strong-field, high-gradient polarity inversion lines. An investigation of historical observational data suggests the possibility that the largest solar ARs, with magnetic flux of 2 × 10{sup 23} Mx, might be able to produce “superflares” with energies of the order of 10{sup 34} erg. The proportionality between the flare durations and magnetic energies is consistent with stellar flare observations, suggesting a common physical background for solar and stellar flares.

High-resolution digital movies of emerging flux and horizontal flows in active regions on the sun

International Nuclear Information System (INIS)

Topka, K.; Ferguson, S.; Frank, Z.; Tarbell, T.; Title, A.

1988-01-01

High-resolution observations of active regions in many wavelength bands obtained at the Vacuum Tower Telescope of NSO/Sunspot (Sacramento Peak) are presented. The SOUP tunable filter, HRSO 1024 x 1024 CCD camera, and a sunspot tracker for image stabilization were used. Subarrays of 512 x 512 pixels were processed digitally and recorded on videodisk in movie format. The movies with 0.5 to 1 arcsecond resolution of the following simultaneous observations were shown: green continuum, longitudinal magnetogram, Doppler velocity, Fe I 5576 A line center, H alpha wings, and H alpha line center. The best set of movies show a 90 x 90 arcsecond field-of-view of an active region at S29, W11. When viewed at speeds of a few thousand times real-time, the photospheric movies clearly show the active region fields being distorted by a remarkable combination of systematic flows and small eruptions of new flux. Flux emergence is most easily discovered in line center movies: an elongated dark feature appears first, followed soon after by bright points at one or both ends. A brief, strong upflow is seen when the dark feature first appears; downflow in the bright points persists much longer. The magnetic flux appears to increase gradually over this extended period. Some of the flux emergence events were studied in detail, with measurements of horizontal and vertical velocities and magnetic flux versus time within one footpoint of the loop

High-resolution digital movies of emerging flux and horizontal flows in active regions on the sun

Science.gov (United States)

Topka, K.; Ferguson, S.; Frank, Z.; Tarbell, T.; Title, A.

1988-01-01

High-resolution observations of active regions in many wavelength bands obtained at the Vacuum Tower Telescope of NSO/Sunspot (Sacramento Peak) are presented. The SOUP tunable filter, HRSO 1024 x 1024 CCD camera, and a sunspot tracker for image stabilization were used. Subarrays of 512 x 512 pixels were processed digitally and recorded on videodisk in movie format. The movies with 0.5 to 1 arcsecond resolution of the following simultaneous observations were shown: green continuum, longitudinal magnetogram, Doppler velocity, Fe I 5576 A line center, H alpha wings, and H alpha line center. The best set of movies show a 90 x 90 arcsecond field-of-view of an active region at S29, W11. When viewed at speeds of a few thousand times real-time, the photospheric movies clearly show the active region fields being distorted by a remarkable combination of systematic flows and small eruptions of new flux. Flux emergence is most easily discovered in line center movies: an elongated dark feature appears first, followed soon after by bright points at one or both ends. A brief, strong upflow is seen when the dark feature first appears; downflow in the bright points persists much longer. The magnetic flux appears to increase gradually over this extended period. Some of the flux emergence events were studied in detail, with measurements of horizontal and vertical velocities and magnetic flux versus time within one footpoint of the loop.

High-resolution digital movies of emerging flux and horizontal flows in active regions on the sun

Science.gov (United States)

Topka, K.; Ferguson, S.; Frank, Z.; Tarbell, T.; Title, A.

1988-11-01

High-resolution observations of active regions in many wavelength bands obtained at the Vacuum Tower Telescope of NSO/Sunspot (Sacramento Peak) are presented. The SOUP tunable filter, HRSO 1024 x 1024 CCD camera, and a sunspot tracker for image stabilization were used. Subarrays of 512 x 512 pixels were processed digitally and recorded on videodisk in movie format. The movies with 0.5 to 1 arcsecond resolution of the following simultaneous observations were shown: green continuum, longitudinal magnetogram, Doppler velocity, Fe I 5576 A line center, H alpha wings, and H alpha line center. The best set of movies show a 90 x 90 arcsecond field-of-view of an active region at S29, W11. When viewed at speeds of a few thousand times real-time, the photospheric movies clearly show the active region fields being distorted by a remarkable combination of systematic flows and small eruptions of new flux. Flux emergence is most easily discovered in line center movies: an elongated dark feature appears first, followed soon after by bright points at one or both ends. A brief, strong upflow is seen when the dark feature first appears; downflow in the bright points persists much longer. The magnetic flux appears to increase gradually over this extended period. Some of the flux emergence events were studied in detail, with measurements of horizontal and vertical velocities and magnetic flux versus time within one footpoint of the loop.

Visual Circular Analysis of 266 Years of Sunspot Counts.

Science.gov (United States)

Buelens, Bart

2016-06-01

Sunspots, colder areas that are visible as dark spots on the surface of the Sun, have been observed for centuries. Their number varies with a period of ∼11 years, a phenomenon closely related to the solar activity cycle. Recently, observation records dating back to 1749 have been reassessed, resulting in the release of a time series of sunspot numbers covering 266 years of observations. This series is analyzed using circular analysis to determine the periodicity of the occurrence of solar maxima. The circular analysis is combined with spiral graphs to provide a single visualization, simultaneously showing the periodicity of the series, the degree to which individual cycle lengths deviate from the average period, and differences in levels reached during the different maxima. This type of visualization of cyclic time series with varying cycle lengths in which significant events occur periodically is broadly applicable. It is aimed particularly at science communication, education, and public outreach.

Extreme Value Theory Applied to the Millennial Sunspot Number Series

Science.gov (United States)

Acero, F. J.; Gallego, M. C.; García, J. A.; Usoskin, I. G.; Vaquero, J. M.

2018-01-01

In this work, we use two decadal sunspot number series reconstructed from cosmogenic radionuclide data (14C in tree trunks, SN 14C, and 10Be in polar ice, SN 10Be) and the extreme value theory to study variability of solar activity during the last nine millennia. The peaks-over-threshold technique was used to compute, in particular, the shape parameter of the generalized Pareto distribution for different thresholds. Its negative value implies an upper bound of the extreme SN 10Be and SN 14C timeseries. The return level for 1000 and 10,000 years were estimated leading to values lower than the maximum observed values, expected for the 1000 year, but not for the 10,000 year return levels, for both series. A comparison of these results with those obtained using the observed sunspot numbers from telescopic observations during the last four centuries suggests that the main characteristics of solar activity have already been recorded in the telescopic period (from 1610 to nowadays) which covers the full range of solar variability from a Grand minimum to a Grand maximum.

Records of auroral candidates and sunspots in Rikkokushi, chronicles of ancient Japan from early 7th century to 887

Science.gov (United States)

Hayakawa, Hisashi; Iwahashi, Kiyomi; Tamazawa, Harufumi; Ebihara, Yusuke; Kawamura, Akito Davis; Isobe, Hiroaki; Namiki, Katsuko; Shibata, Kazunari

2017-12-01

We present the results of the surveys on sunspots and auroral candidates in Rikkokushi, Japanese official histories from the early 7th century to 887, to review the solar and auroral activities. In total, we found one sunspot record and 13 auroral candidates in Rikkokushi. We then examine the records of the sunspots and auroral candidates, compare the auroral candidates with the lunar phase to estimate their reliability, and compare the records of the sunspots and auroral candidates with the contemporary total solar irradiance reconstructed from radioisotope data. We also identify the locations of the observational sites to review possible equatorward expansion of the auroral oval. These discussions suggest a major gap in auroral candidates from the late 7th to early 9th centuries, which includes the candidate of the grand minimum reconstructed from the radioisotope data, a similar tendency as the distributions of sunspot records in contemporary China, and a relatively high magnetic latitude of observational sites with a higher potential for observing aurorae more frequently than at present.

INTERFERENCE OF THE RUNNING WAVES AT LIGHT BRIDGES OF A SUNSPOT

Energy Technology Data Exchange (ETDEWEB)

Su, J. T.; Priya, T. G.; Yu, S. J.; Zhang, M. [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Ji, K. F. [Kunming University of Science and Technology, Kunming 650093 (China); Banerjee, D. [Indian Institute of Astrophysics, Koramangala Bangalore 560034 (India); Cao, W. D. [Big Bear Solar Observatory, 40386 North Shore Lane, Big Bear City, CA 92314 (United States); Zhao, J. S.; Ji, H. S., E-mail: jt@bao.ac.cn [Purple Mountain Observatory, CAS, Nanjing 210008 (China)

2016-01-01

The observations of chromospheric oscillations of two umbral light bridges (LBs) within a sunspot from NOAA Active Region 12127 are presented. It was found that the running umbral waves with periods of 2.2–2.6 minutes underwent very fast damping before approaching umbral boundaries, while those with higher periods (>2.6 minutes) could propagate outside umbrae. On two sides of each LB adjacent to umbrae, the cross-wavelet spectra displayed that the oscillations on them had a common significant power region with dominant frequencies of 2–6 minutes and phase differences of ∼90°. A counterstream of two running umbral waves in the 2–6 minute frequency range propagated toward the LBs, where they encountered each other and gave rise to constructive or even destructive interference on the LBs. In addition, the velocity and density perturbations on the LBs were found in opposite phases suggesting that the perturbations were caused by the downward propagating waves.

Initial phase of the development of sunspot groups and their forecast

International Nuclear Information System (INIS)

Berlyand, B.O.; Burov, V.A.; Stepanyan, N.N.

1979-01-01

Some characteristics of the initial phase of sunspot groups and their forecast have been considered. Experimental data on 340 sunspot groups were obtained in 1967-1969. It was found that oscillations of the magnetic flux in the groups indicate the possibility of the existence of typical periods (2 and 4 days) of the magnetic field development. Most of the groups appears in young plages. The probability of the protons injection from the young groups is very small. The typical time of the development of the proton centre is 10-30 days. The characteristics of the group on the first day of its existence are vaguely connected with the lifetime of the group. On the second and third days the magnetic characteristics (the summary magnetic flux and the number of the unipolar regions) have the highest correlation coefficient (approximately 70%) with the lifetime of the group. The problem of the group lifetime forecast was being solved with the pattern recognition technique. On the base of the second day observation of the existence of the group verification of the received forecast 14% exceeds the verification of the climatological forecast. The forecast of the Zurich class with the same technique is effective beginning with the fifth day of the group existence and the forecast of the flare activity of the group since the day of its appearance. The exceeding of the verification as compared with the climatological forecasts in these problems is 10% and 8% accordingly

DETECTION OF SUPERSONIC DOWNFLOWS AND ASSOCIATED HEATING EVENTS IN THE TRANSITION REGION ABOVE SUNSPOTS

Energy Technology Data Exchange (ETDEWEB)

Kleint, L.; Martínez-Sykora, J. [Bay Area Environmental Research Institute, 625 2nd Street, Ste. 209, Petaluma, CA (United States); Antolin, P. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Tian, H.; Testa, P.; Reeves, K. K.; McKillop, S.; Saar, S.; Golub, L. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Judge, P. [High Altitude Observatory/NCAR, P.O. Box 3000, Boulder, CO 80307 (United States); De Pontieu, B.; Wuelser, J. P.; Boerner, P.; Hurlburt, N.; Lemen, J.; Tarbell, T. D.; Title, A. [Lockheed Martin Solar and Astrophysics Laboratory, 3251 Hanover St., Org. ADBS, Bldg. 252, Palo Alto, CA 94304 (United States); Carlsson, M.; Hansteen, V. [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, NO-0315 Oslo (Norway); Jaeggli, S., E-mail: lucia.kleint@fhnw.ch [Department of Physics, Montana State University, Bozeman, P.O. Box 173840, Bozeman, MT 59717 (United States); and others

2014-07-10

Interface Region Imaging Spectrograph data allow us to study the solar transition region (TR) with an unprecedented spatial resolution of 0.''33. On 2013 August 30, we observed bursts of high Doppler shifts suggesting strong supersonic downflows of up to 200 km s{sup –1} and weaker, slightly slower upflows in the spectral lines Mg II h and k, C II 1336, Si IV 1394 Å, and 1403 Å, that are correlated with brightenings in the slitjaw images (SJIs). The bursty behavior lasts throughout the 2 hr observation, with average burst durations of about 20 s. The locations of these short-lived events appear to be the umbral and penumbral footpoints of EUV loops. Fast apparent downflows are observed along these loops in the SJIs and in the Atmospheric Imaging Assembly, suggesting that the loops are thermally unstable. We interpret the observations as cool material falling from coronal heights, and especially coronal rain produced along the thermally unstable loops, which leads to an increase of intensity at the loop footpoints, probably indicating an increase of density and temperature in the TR. The rain speeds are on the higher end of previously reported speeds for this phenomenon, and possibly higher than the free-fall velocity along the loops. On other observing days, similar bright dots are sometimes aligned into ribbons, resembling small flare ribbons. These observations provide a first insight into small-scale heating events in sunspots in the TR.

Identification of possible intense historical geomagnetic storms using combined sunspot and auroral observations from East Asia

Directory of Open Access Journals (Sweden)

D. M. Willis

2005-03-01

Full Text Available Comprehensive catalogues of ancient sunspot and auroral observations from East Asia are used to identify possible intense historical geomagnetic storms in the interval 210 BC-AD 1918. There are about 270 entries in the sunspot catalogue and about 1150 entries in the auroral catalogue. Special databases have been constructed in which the scientific information in these two catalogues is placed in specified fields. For the purposes of this study, an historical geomagnetic storm is defined in terms of an auroral observation that is apparently associated with a particular sunspot observation, in the sense that the auroral observation occurred within several days of the sunspot observation. More precisely, a selection criterion is formulated for the automatic identification of such geomagnetic storms, using the oriental records stored in the sunspot and auroral databases. The selection criterion is based on specific assumptions about the duration of sunspot visibility with the unaided eye, the likely range of heliographic longitudes of an energetic solar feature, and the likely range of transit times for ejected solar plasma to travel from the Sun to the Earth. This selection criterion results in the identification of nineteen putative historical geomagnetic storms, although two of these storms are spurious in the sense that there are two examples of a single sunspot observation being associated with two different auroral observations separated by more than half a (synodic solar rotation period. The literary and scientific reliabilities of the East Asian sunspot and auroral records that define the nineteen historical geomagnetic storms are discussed in detail in a set of appendices. A possible time sequence of events is presented for each geomagnetic storm, including possible dates for both the central meridian passage of the sunspot and the occurrence of the energetic solar feature, as well as likely transit times for the ejected solar plasma

On the structure of a magnetic field and its evolution in the vicinity of sunspots

International Nuclear Information System (INIS)

Gopasyuk, S.I.; Kartashova, L.G.

1981-01-01

The structure of magnetic field and its evolution around single large sunspots has been studied. For this purpose observational data of the longitudinal magnetic field on the photospheric level and hsub(α) filtergrams for 18 active regions have been used. It is shown that there are characteristic directions corresponding to the transition of the spot field without sign change into an extended region of the same polarity and coinciding with extended (100000-300000 km) systems of filamentary feature chains of the fine chromospheric structure in active region. The horizontal magnetic f+eld component of the spot (systems of filamentary feature chains of the fine chromospheric structure) disappears on an extended region of chromospheric surface in the direction, where the satellite field (the field of opposite polarity) appears near its boundary. On the other hand, when satellite field disappears at some direction from the spot the transversal magnetic field appears on the extended surface region of the chromosphere keeping the same direction. One of the possible causes of disappearance of the transversal magnetic field on an extended region in the chromosphere might be the reconnection of magnetic lines of force [ru

Investigation of Quasi-periodic Solar Oscillations in Sunspots Based on SOHO/MDI Magnetograms

Science.gov (United States)

Kallunki, J.; Riehokainen, A.

2012-10-01

In this work we study quasi-periodic solar oscillations in sunspots, based on the variation of the amplitude of the magnetic field strength and the variation of the sunspot area. We investigate long-period oscillations between three minutes and ten hours. The magnetic field synoptic maps were obtained from the SOHO/MDI. Wavelet (Morlet), global wavelet spectrum (GWS) and fast Fourier transform (FFT) methods are used in the periodicity analysis at the 95 % significance level. Additionally, the quiet Sun area (QSA) signal and an instrumental effect are discussed. We find several oscillation periods in the sunspots above the 95 % significance level: 3 - 5, 10 - 23, 220 - 240, 340 and 470 minutes, and we also find common oscillation periods (10 - 23 minutes) between the sunspot area variation and that of the magnetic field strength. We discuss possible mechanisms for the obtained results, based on the existing models for sunspot oscillations.

Automated Segmentation of High-Resolution Photospheric Images of Active Regions

Science.gov (United States)

Yang, Meng; Tian, Yu; Rao, Changhui

2018-02-01

Due to the development of ground-based, large-aperture solar telescopes with adaptive optics (AO) resulting in increasing resolving ability, more accurate sunspot identifications and characterizations are required. In this article, we have developed a set of automated segmentation methods for high-resolution solar photospheric images. Firstly, a local-intensity-clustering level-set method is applied to roughly separate solar granulation and sunspots. Then reinitialization-free level-set evolution is adopted to adjust the boundaries of the photospheric patch; an adaptive intensity threshold is used to discriminate between umbra and penumbra; light bridges are selected according to their regional properties from candidates produced by morphological operations. The proposed method is applied to the solar high-resolution TiO 705.7-nm images taken by the 151-element AO system and Ground-Layer Adaptive Optics prototype system at the 1-m New Vacuum Solar Telescope of the Yunnan Observatory. Experimental results show that the method achieves satisfactory robustness and efficiency with low computational cost on high-resolution images. The method could also be applied to full-disk images, and the calculated sunspot areas correlate well with the data given by the National Oceanic and Atmospheric Administration (NOAA).

On the chromospheric network structure around deVeloped groups of sunspots

International Nuclear Information System (INIS)

Kartashova, L.G.

1980-01-01

The chromospheric network structure around several developed groups of sunspots were studied on the basis of the observations in the Hsub(α) line. The resolution on the filtergrams was of 2. The following was found: 1) in the neighbourhood of the groups of sunspots 70% (from 870) of network cells stretch along fibrils direction (with accuracy 30 deg), and 15% of cells stretch approximately across that (at angles 70-90 deg); 2) out of the boundary of the main radial fibrils structure the groups of sunspots is often rounded by the system of network cells stretched approximately perpendicular to radial direction

The visibility function and its effect on the observed characteristics of sunspot groups. 1

International Nuclear Information System (INIS)

Kopecky, M.; Kuklin, G.V.; Starkova, I.P.

1985-01-01

The paper is an introductory study to a series dealing with the visibility function, the function of foreshortening of sunspot group areas, and with the effect of these functions on the results of the statistical processing of observations, which has to be taken into account in interpreting the results. A ''diagram of observational conditions'' is described, which enables a number of statistical problems of sunspot groups on the rotating Sun to be solved by computer modelling or by graphical methods. Examples are given of the use of this diagram in studying the distribution of the observed lifetime of sunspot groups with a given actual lifetime, of the decrease in the number of sunspot groups towards the limb of the solar disc, of the east-west asymmetry of sunspot group appearance and disappearance. (author)

Sunspot Equilibria in a Production Economy: Do Rational Animal Spirits Cause Overproduction?

OpenAIRE

Kajii, Atsushi

2008-01-01

We study a standard two period economy with one nominal bond and one firm. The input of the firm is done in the first period and financed with the nominal bond, and its profits are distributed to the shareholders in the second period. We show that a sunspot equilibrium exists around each efficient equilibrium. The interest rate is lower than optimal and there is over production in sunspot equilibria, under some conditions. But a sunspot equilibrium does not exist if the profit share can be tr...

The use of solar faculae in studies of the sunspot cycle

International Nuclear Information System (INIS)

Brown, G.M.; Evans, R.

1980-01-01

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. (orig.)

Physical Properties of Umbral Dots Observed in Sunspots: A Hinode Observation

Science.gov (United States)

Yadav, Rahul; Mathew, Shibu K.

2018-04-01

Umbral dots (UDs) are small-scale bright features observed in the umbral part of sunspots and pores. It is well established that they are manifestations of magnetoconvection phenomena inside umbrae. We study the physical properties of UDs in different sunspots and their dependence on decay rate and filling factor. We have selected high-resolution, G-band continuum filtergrams of seven sunspots from Hinode to study their physical properties. We have also used Michelson Doppler Imager (MDI) continuum images to estimate the decay rate of selected sunspots. An identification and tracking algorithm was developed to identify the UDs in time sequences. The statistical analysis of UDs exhibits an averaged maximum intensity and effective diameter of 0.26 I_{QS} and 270 km. Furthermore, the lifetime, horizontal speed, trajectory length, and displacement length (birth-death distance) of UDs are 8.19 minutes, 0.5 km s-1, 284 km, and 155 km, respectively. We also find a positive correlation between intensity-diameter, intensity-lifetime, and diameter-lifetime of UDs. However, UD properties do not show any significant relation with the decay rate or filling factor.

On the structure of small sunspots

International Nuclear Information System (INIS)

Ringnes, T.S.

1984-01-01

The smallest and most short-lived sunspots are decribed differently at the observatories in Zuerich and Greenwich. These differences which seem to originate both from the observing procedure and from the definitions of penumbra and umbra adopted, are further discussed

Sunspot number recalibration: The ~1840–1920 anomaly in the observer normalization factors of the group sunspot number

Directory of Open Access Journals (Sweden)

Cliver Edward W.

2017-01-01

Full Text Available We analyze the normalization factors (k′-factors used to scale secondary observers to the Royal Greenwich Observatory (RGO reference series of the Hoyt & Schatten (1998a, 1998b group sunspot number (GSN. A time series of these k′-factors exhibits an anomaly from 1841 to 1920, viz., the average k′-factor for all observers who began reporting groups from 1841 to 1883 is 1.075 vs. 1.431 for those who began from 1884 to 1920, with a progressive rise, on average, during the latter period. The 1883–1884 break between the two subintervals occurs precisely at the point where Hoyt and Schatten began to use a complex daisy-chaining method to scale observers to RGO. The 1841–1920 anomaly implies, implausibly, that the average sunspot observer who began from 1841 to 1883 was nearly as proficient at counting groups as mid-20th century RGO (for which k′ = 1.0 by definition while observers beginning during the 1884–1920 period regressed in group counting capability relative to those from the earlier interval. Instead, as shown elsewhere and substantiated here, RGO group counts increased relative to those of other long-term observers from 1874 to ~1915. This apparent inhomogeneity in the RGO group count series is primarily responsible for the increase in k′-factors from 1884 to 1920 and the suppression, by 44% on average, of the Hoyt and Schatten GSN relative to the original Wolf sunspot number (WSN before ~1885. Correcting for the early “learning curve” in the RGO reference series and minimizing the use of daisy-chaining rectifies the anomalous behavior of the k′-factor series. The resultant GSN time series (designated GSN* is in reasonable agreement with the revised WSN (SN*; Clette & Lefèvre 2016 and the backbone-based group sunspot number (RGS; Svalgaard & Schatten 2016 but significantly higher than other recent reconstructions (Friedli, personal communication, 2016; Lockwood et al. 2014a, 2014b; Usoskin et al. 2016a. This result

Active region fine structure observed at 0.08 arcsec resolution

Czech Academy of Sciences Publication Activity Database

Schlichenmaier, R.; von der Lühe, O.; Hoch, S.; Soltau, D.; Berkefeld, T.; Schmidt, D.; Schmidt, W.; Denker, C.; Balthasar, H.; Hofmann, A.; Strassmeier, K.G.; Staude, J.; Feller, A.; Lagg, A.; Solanki, S.K.; Collados Vera, M.; Sigwarth, M.; Volkmer, R.; Waldmann, T.A.; Kneer, F.; Nicklas, H.; Sobotka, Michal

2016-01-01

Roč. 596, December (2016), A7/1-A7/8 ISSN 0004-6361 EU Projects: European Commission(XE) 312495 - SOLARNET Institutional support: RVO:67985815 Keywords : Sun * activity * sunspots Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.378, year: 2014

Sunspots sketches during the solar eclipses of 9th January and 29th December of 1777 in Mexico

Science.gov (United States)

Domínguez-Castro, Fernando; Gallego, María Cruz; Vaquero, José Manuel

2017-06-01

Two sunspot observations recorded by the Mexican Felipe de Zúñiga y Ontiveros have been revealed from a manuscript. One sunspot group was recorded on 9th January 1777 and four sunspot groups on 29th December 1777. Both records were taken during the observation of solar eclipses from Mexico City and their description also included sketches of the solar disk with sunspots. The sunspot group corresponding to 9th January was also observed by Erasmus Lievog. The observation on 29th December 1777 is the only record corresponding to this date.

The Earth's Interaction With the Sun Over the Millennia From Analyses of Historical Sunspot, Auroral and Climate Records

Science.gov (United States)

Yau, K.

2001-12-01

A prolonged decrease in the Sun's irradiance during the Maunder Minimum has been proposed as a cause of the Little Ice Age ({ca} 1600-1800). Eddy [{Science} {192}, 1976, 1189] made this suggestion after noting that very few sunspots were observed from 1645 to 1715, indicative of a weakened Sun. Pre-telescopic Oriental sunspot records go back over 2200 years. Periods when no sunspots were seen have been documented by, {eg}, Clark [{Astron} {7}, 2/1979, 50]. Abundances of C 14 in tree rings and Be10 in ice cores are also good indicators of past solar activity. These isotopes are produced by cosmic rays high in the atmosphere. When the Sun is less active more of them are made and deposited at ground level. There is thus a strong {negative} correlation between their abundances and sunspot counts. Minima of solar activity in tree rings and a south polar ice core have been collated by, {eg}, Bard [{Earth Planet Sci Lett} {150} 1997, 453]; and show striking correspondence with periods when no sunspots were seen, centered at {ca} 900, 1050, 1500, 1700. Pang and Yau [{Eos} {79}, #45, 1998, F149] investigated the Medieval Minimum at 700, using in addition the frequency of auroral sighting7s, a good indicator of solar activity too [Yau, PhD thesis, 1988]; and found that the progression of minima in solar activity goes back to 700. Auroral frequency, C 14 and Be 10 concentrations are also affected by variations in the geomagnetic field. Deposition changes can also influence C 14 and Be 10 abundances. Sunspot counts are thus the only true indicator of solar activity. The Sun's bolometric variations (-0.3% for the Maunder Minimum) can contribute to climatic changes (\\0.5° C for the Little Ice Age)[{eg}, Lean, {GRL} {22}, 1995, 3195]. For times with no thermometer data, temperature can be estimated from, {eg}, Oxygen 18 isotopic abundance in ice cores, which in turn depends on the temperature of the ocean water it evaporated from. We have linked the Medieval Minimum to the cold

Statistics of the largest sunspot and facular areas per solar cycle

International Nuclear Information System (INIS)

Willis, D.M.; Kabasakal Tulunay, Y.

1979-01-01

The statistics of extreme values is used to investigate the statistical properties of the largest areas sunspots and photospheric faculae per solar cycle. The largest values of the synodic-solar-rotation mean areas of umbrae, whole spots and faculae, which have been recorded for nine solar cycles, are each shown to comply with the general form of the extreme value probability function. Empirical expressions are derived for the three extreme value populations from which the characteristic statistical parameters, namely the mode, median, mean and standard deviation, can be calculated for each population. These three extreme value populations are also used to find the expected ranges of the extreme areas in a group of solar cycles as a function of the number of cycles in the group. The extreme areas of umbrae and whole spots have a dispersion comparable to that found by Siscoe for the extreme values of sunspot number, whereas the extreme areas of faculae have a smaller dispersion which is comparable to that found by Siscoe for the largest geomagnetic storm per solar cycle. The expected range of the largest sunspot area per solar cycle for a group of one hundred cycles appears to be inconsistent with the existence of the prolonged periods of sunspot minima that have been inferred from the historical information on solar variability. This inconsistency supports the contention that there are temporal changes of solar-cycle statistics during protracted periods of sunspot minima (or maxima). Indeed, without such temporal changes, photospheric faculae should have been continually observable throughout the lifetime of the Sun. (orig.)

On two populations of sunspot groups

International Nuclear Information System (INIS)

Kuklin, G.V.

1980-01-01

The principal component method was applied studying the sunspot groups distribution in respect to the maximum area for the individual 11-year cycles 12 to 19 (Lopez Arroyo and Lahulla, 1974) and for the years 1900 to 1964 (Mandrykina, 1974). The existence of two populations of sunspot groups is confirmed. The variations of the importance parameter q, which determines the population shares, in the 80-, 22- and 11-year cycles are considered. The obtained maximal area distributions for populations I and II are approximated by linear combination of logarithmic-normal distributions, the subpopulations Ia, Ib, Ic by the most probable maximum areas of 22, 298 and 90 mvh, respectively, and the subpopulations IIa, IIb, IIc by the most probable maximal areas of 6, 142 and 754 mvh, respectively. The characteristic distinction between populations I and II is apparently the magnetic structure of the groups belonging to them (bipolar and unipolar ones). (author)

Sunspot variation and selected associated phenomena: a look at solar cycle 21 and beyond

International Nuclear Information System (INIS)

Wilson, R.M.

1982-02-01

Solar sunspot cycles 8 through 21 are reviewed. Mean time intervals are calculated for maximum to maximum, minimum to minimum, minimum to maximum, and maximum to minimum phases for cycles 8 through 20 and 8 through 21. Simple cosine functions with a period of 132 years are compared to, and found to be representative of, the variation of smoothed sunspot numbers at solar maximum and minimum. A comparison of cycles 20 and 21 is given, leading to a projection for activity levels during the Spacelab 2 era (tentatively, November 1984). A prediction is made for cycle 22. Major flares are observed to peak several months subsequent to the solar maximum during cycle 21 and to be at minimum level several months after the solar minimum. Additional remarks are given for flares, gradual rise and fall radio events and 2800 MHz radio emission. Certain solar activity parameters, especially as they relate to the near term Spacelab 2 time frame are estimated

MEASUREMENTS OF THE ABSORPTION AND SCATTERING CROSS SECTIONS FOR THE INTERACTION OF SOLAR ACOUSTIC WAVES WITH SUNSPOTS

International Nuclear Information System (INIS)

Zhao, Hui; Chou, Dean-Yi

2016-01-01

The solar acoustic waves are modified by the interaction with sunspots. The interaction can be treated as a scattering problem: an incident wave propagating toward a sunspot is scattered by the sunspot into different modes. The absorption cross section and scattering cross section are two important parameters in the scattering problem. In this study, we use the wavefunction of the scattered wave, measured with a deconvolution method, to compute the absorption cross section σ ab and the scattering cross section σ sc for the radial order n = 0–5 for two sunspots, NOAA 11084 and NOAA 11092. In the computation of the cross sections, the random noise and dissipation in the measured acoustic power are corrected. For both σ ab and σ sc , the value of NOAA 11092 is greater than that of NOAA 11084, but their overall n dependence is similar: decreasing with n . The ratio of σ ab of NOAA 11092 to that of NOAA 11084 approximately equals the ratio of sunspot radii for all n , while the ratio of σ sc of the two sunspots is greater than the ratio of sunspot radii and increases with n . This suggests that σ ab is approximately proportional to the sunspot radius, while the dependence of σ sc on radius is faster than the linear increase.

MEASUREMENTS OF THE ABSORPTION AND SCATTERING CROSS SECTIONS FOR THE INTERACTION OF SOLAR ACOUSTIC WAVES WITH SUNSPOTS

Energy Technology Data Exchange (ETDEWEB)

Zhao, Hui [National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 200012 (China); Chou, Dean-Yi, E-mail: chou@phys.nthu.edu.tw [Physics Department, National Tsing Hua University, Hsinchu, Taiwan (China)

2016-05-01

The solar acoustic waves are modified by the interaction with sunspots. The interaction can be treated as a scattering problem: an incident wave propagating toward a sunspot is scattered by the sunspot into different modes. The absorption cross section and scattering cross section are two important parameters in the scattering problem. In this study, we use the wavefunction of the scattered wave, measured with a deconvolution method, to compute the absorption cross section σ {sub ab} and the scattering cross section σ {sub sc} for the radial order n = 0–5 for two sunspots, NOAA 11084 and NOAA 11092. In the computation of the cross sections, the random noise and dissipation in the measured acoustic power are corrected. For both σ {sub ab} and σ {sub sc}, the value of NOAA 11092 is greater than that of NOAA 11084, but their overall n dependence is similar: decreasing with n . The ratio of σ {sub ab} of NOAA 11092 to that of NOAA 11084 approximately equals the ratio of sunspot radii for all n , while the ratio of σ {sub sc} of the two sunspots is greater than the ratio of sunspot radii and increases with n . This suggests that σ {sub ab} is approximately proportional to the sunspot radius, while the dependence of σ {sub sc} on radius is faster than the linear increase.

Solar magnetic field studies using the 12 micron emission lines. I - Quiet sun time series and sunspot slices

Science.gov (United States)

Deming, Drake; Boyle, Robert J.; Jennings, Donald E.; Wiedemann, Gunter

1988-01-01

The use of the extremely Zeeman-sensitive IR emission line Mg I, at 12.32 microns, to study solar magnetic fields. Time series observations of the line in the quiet sun were obtained in order to determine the response time of the line to the five-minute oscillations. Based upon the velocity amplitude and average period measured in the line, it is concluded that it is formed in the temperature minimum region. The magnetic structure of sunspots is investigated by stepping a small field of view in linear 'slices' through the spots. The region of penumbral line formation does not show the Evershed outflow common in photospheric lines. The line intensity is a factor of two greater in sunspot penumbrae than in the photosphere, and at the limb the penumbral emission begins to depart from optical thinness, the line source function increasing with height. For a spot near disk center, the radial decrease in absolute magnetic field strength is steeper than the generally accepted dependence.

Simultaneous SMM flat crystal spectrometer and Very Large Array observations of solar active regions

Science.gov (United States)

Lang, Kenneth R.; Willson, Robert F.; Smith, Kermit L.; Strong, Keith T.

1987-01-01

High-resolution images of the quiescent emission from two solar active regions at 20 cm (VLA) and soft X-ray (SMM FCS) wavelengths are compared. There are regions where the X-ray coronal loops have been completely imaged at 20 cm wavelength. In other regions, the X-ray radiation was detected without detectable 20 cm radiation, and vice versa. The X-ray data were used to infer average electron temperatures of about 3-million K and average electron densities of about 2.5 x 10 to the 9th/cu cm for the X-ray emitting plasma in the two active regions. The thermal bremsstrahlung of the X-ray emitting plasma is optically thin at 20 cm wavelength. The 20 cm brightness temperatures were always less than T(e), which is consistent with optically thin bremsstrahlung. The low T(B) can be explained if a higher, cooler plasma covers the hotter X-ray emitting plasma. Thermal gyroresonance radiation must account for the intense 20 cm radiation near and above sunspots where no X-ray radiation is detected.

TRACING p -MODE WAVES FROM THE PHOTOSPHERE TO THE CORONA IN ACTIVE REGIONS

Energy Technology Data Exchange (ETDEWEB)

Zhao, Junwei; Chen, Ruizhu [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305-4085 (United States); Felipe, Tobías; Khomenko, Elena [Instituto de Astrofísica de Canarias, E-38025 La Laguna, Tenerife (Spain)

2016-10-10

Atmosphere above sunspots is abundant with different types of waves. Among these waves are running penumbral waves in the chromosphere, quasi-periodic oscillations in the lower coronal loops, and recently reported running waves in sunspots’ photosphere, all of which were interpreted as magnetoacoustic waves by some authors. Are these waves in different atmospheric layers related to each other, what is the nature of these waves, and where are the ultimate sources of these waves? Applying a time–distance helioseismic analysis over a suite of multi-wavelength observations above a sunspot, we demonstrate that the helioseismic p -mode waves are able to channel up from the photosphere through the chromosphere and transition region into the corona, and that the magnetoacoustic waves observed in different atmospheric layers are a same wave originating from the photosphere but exhibiting differently under different physical conditions. We also show waves of different frequencies travel along different paths, which can be used to derive the physical properties of the atmosphere above sunspots. Our numerical simulation of traveling of waves from a subphotospheric source qualitatively resembles the observed properties of the waves and offers an interpretation of the shapes of the wavefronts above the photosphere.

Study of the Effect of Active Regions on the Scattering Polarization in the Solar Corona

Science.gov (United States)

Derouich, M.; Badruddin

2018-03-01

The solar photospheric/chromospheric light exciting atoms/ions is not homogeneous because of the presence of active regions (ARs). The effect of ARs on the scattering polarization at the coronal level is an important ingredient for a realistic determination of the magnetic field. This effect is usually disregarded or mixed with other effects in the sense that the degree of its importance is not well known. The aim of this paper is to study the effect of atmospheric inhomogeneities on the coronal scattering polarization. We determined quantitatively the importance of the atmospheric inhomogeneities by using given geometries of solar ARs (plages and sunspots).

Photospheric Origin of Three-minute Oscillations in a Sunspot

Energy Technology Data Exchange (ETDEWEB)

Chae, Jongchul; Lee, Jeongwoo; Cho, Kyuhyoun; Song, Donguk [Astronomy Program, Department of Physics and Astronomy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826 (Korea, Republic of); Cho, Kyungsuk; Yurchyshyn, Vasyl [Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon 34055 (Korea, Republic of)

2017-02-10

The origin of the three-minute oscillations of intensity and velocity observed in the chromosphere of sunspot umbrae is still unclear. We investigated the spatio-spectral properties of the 3 minute oscillations of velocity in the photosphere of a sunspot umbra as well as those in the low chromosphere using the spectral data of the Ni i λ 5436, Fe i λ 5435, and Na i D{sub 2} λ 5890 lines taken by the Fast Imaging Solar Spectrograph of the 1.6 m New Solar Telescope at the Big Bear Solar Observatory. As a result, we found a local enhancement of the 3 minute oscillation power in the vicinities of a light bridge (LB) and numerous umbral dots (UDs) in the photosphere. These 3 minute oscillations occurred independently of the 5 minute oscillations. Through wavelet analysis, we determined the amplitudes and phases of the 3 minute oscillations at the formation heights of the spectral lines, and they were found to be consistent with the upwardly propagating slow magnetoacoustic waves in the photosphere with energy flux large enough to explain the chromospheric oscillations. Our results suggest that the 3 minute chromospheric oscillations in this sunspot may have been generated by magnetoconvection occurring in the LB and UDs.

Dynamics of Subarcsecond Bright Dots in the Transition Region above Sunspots and Their Relation to Penumbral Micro-jets

Energy Technology Data Exchange (ETDEWEB)

Samanta, Tanmoy; Banerjee, Dipankar [Indian Institute of Astrophysics, Koramangala, Bangalore 560034 (India); Tian, Hui [School of Earth and Space Sciences, Peking University (China); Schanche, Nicole, E-mail: tsamanta@iiap.res.in, E-mail: huitian@pku.edu.cn, E-mail: dipu@iiap.res.in, E-mail: ns81@st-andrews.ac.uk [University of St. Andrews, St. Andrews (United Kingdom)

2017-02-01

Recent high-resolution observations have revealed that subarcsecond bright dots (BDs) with sub-minute lifetimes appear ubiquitously in the transition region (TR) above sunspot penumbra. The presence of penumbral micro-jets (PMJs) in the chromosphere was previously reported. It was proposed that both the PMJs and BDs are formed due to a magnetic reconnection process and may play an important role in heating of the penumbra. Using simultaneous observations of the chromosphere from the Solar Optical Telescope (SOT) on board Hinode and observations of the TR from the Interface Region Imaging Spectrograph , we study the dynamics of BDs and their relation to PMJs. We find two types of BDs, one that is related to PMJs, and another that does not show any visible dynamics in the SOT Ca ii H images. From a statistical analysis we show that these two types have different properties. The BDs that are related to PMJs always appear at the top of the PMJs, the vast majority of which show inward motion and originate before the generation of the PMJs. These results may indicate that the reconnection occurs at the lower coronal/TR height and initiates PMJs at the chromosphere. This formation mechanism is in contrast with the formation of PMJs by reconnection in the (upper) photosphere between differently inclined fields.

Outflow of chromospheric emission features from the rim of a sunspot

Science.gov (United States)

Liu, S.-Y.

1973-01-01

In viewing a 16 mm movie made from a time sequence of spectroheliograms, some of these emission features are found to move outward from the rim of the sunspot until they are eventually lost in the small plage. There are two interpretations for the streaming of the magnetic features. It is possible that kinks in the line of force propagate along a horizontal extension of the penumbral magnetic field. Alternatively, fragments of the sunspot magnetic field are carried away by the photospheric velocity field.

SOLAR CYCLE 24: CURIOUS CHANGES IN THE RELATIVE NUMBERS OF SUNSPOT GROUP TYPES

International Nuclear Information System (INIS)

Kilcik, A.; Yurchyshyn, V. B.; Ozguc, A.; Rozelot, J. P.

2014-01-01

Here, we analyze different sunspot group (SG) behaviors from the points of view of both the sunspot counts (SSCs) and the number of SGs, in four categories, for the time period of 1982 January-2014 May. These categories include data from simple (A and B), medium (C), large (D, E, and F), and decaying (H) SGs. We investigate temporal variations of all data sets used in this study and find the following results. (1) There is a very significant decrease in the large groups' SSCs and the number of SGs in solar cycle 24 (cycle 24) compared to cycles 21-23. (2) There is no strong variation in the decaying groups' data sets for the entire investigated time interval. (3) Medium group data show a gradual decrease for the last three cycles. (4) A significant decrease occurred in the small groups during solar cycle 23, while no strong changes show in the current cycle (cycle 24) compared to the previous ones. We confirm that the temporal behavior of all categories is quite different from cycle to cycle and it is especially flagrant in solar cycle 24. Thus, we argue that the reduced absolute number of the large SGs is largely, if not solely, responsible for the weak cycle 24. These results might be important for long-term space weather predictions to understand the rate of formation of different groups of sunspots during a solar cycle and the possible consequences for the long-term geomagnetic activity

HIGH RESOLUTION He i 10830 Å NARROW-BAND IMAGING OF AN M-CLASS FLARE. I. ANALYSIS OF SUNSPOT DYNAMICS DURING FLARING

Energy Technology Data Exchange (ETDEWEB)

Wang, Ya; Su, Yingna; Hong, Zhenxiang; Ji, Haisheng [Key Laboratory of DMSA, Purple Mountain Observatory, CAS, Nanjing, 210008 (China); Zeng, Zhicheng; Goode, Philip R.; Cao, Wenda [Big Bear Solar Observatory, 40386 North Shore Lane, Big Bear City, CA 92314 (United States); Ji, Kaifan [Yunnan Astronomical Observatories, Kunming 650011 (China)

2016-12-20

In this paper, we report our first-step results of high resolution He i 10830 Å narrow-band imaging (bandpass: 0.5 Å) of an M1.8 class two-ribbon flare on 2012 July 5. The flare was observed with the 1.6 m aperture New Solar Telescope at Big Bear Solar Observatory. For this unique data set, sunspot dynamics during flaring were analyzed for the first time. By directly imaging the upper chromosphere, running penumbral waves are clearly seen as an outward extension of umbral flashes; both take the form of absorption in the 10830 Å narrow-band images. From a space–time image made of a slit cutting across a flare ribbon and the sunspot, we find that the dark lanes for umbral flashes and penumbral waves are obviously broadened after the flare. The most prominent feature is the sudden appearance of an oscillating absorption strip inside the ribbon when it sweeps into the sunspot’s penumbral and umbral regions. During each oscillation, outwardly propagating umbral flashes and subsequent penumbral waves rush out into the inwardly sweeping ribbon, followed by a return of the absorption strip with similar speed. We tentatively explain the phenomena as the result of a sudden increase in the density of ortho-helium atoms in the area of the sunspot being excited by the flare’s extreme ultraviolet illumination. This explanation is based on the observation that 10830 Å absorption around the sunspot area gets enhanced during the flare. Nevertheless, questions are still open and we need further well-devised observations to investigate the behavior of sunspot dynamics during flares.

Using dynamo theory to predict the sunspot number during solar cycle 21

Science.gov (United States)

Schatten, K. H.; Scherrer, P. H.; Svalgaard, L.; Wilcox, J. M.

1978-01-01

On physical grounds it is suggested that the polar field strength of the sun near a solar minimum is closely related to the solar activity of the following cycle. Four methods of estimating the polar magnetic field strength of the sun near solar minimum are employed to provide an estimate of the yearly mean sunspot number of cycle 21 at solar maximum of 140 + or - 20. This estimate may be considered a first-order attempt to predict the cycle activity using one parameter of physical importance based upon dynamo theory.

Solar activity and rainfall pattern in Tamil Nadu during the Northeast monsoon

International Nuclear Information System (INIS)

Reddy, R.S.; Mukherjee, B.K.; Ramana Murty, Bh.V.

1976-01-01

An attempt is made to examine the association, of any, between the rainfall, in Tamil Nadu and sunspot activity and if so, whether similar periodicities are also present in the sunspot activity. The daily relative sunspot numbers for the period Oct.-Dec. during 1961-70 and the daily sunspot means for the period Oct.-Dec. 1889-1938, as well as the rainfall series for the period Oct.-Nov., during 1961-70 have been analysed by power spectrum. An anti-phase relation was noticed between the rainfall and the sunspot activity. The 15-day periodicity in the rainfall was significant. The sunspot activity also showed similar periodicities as rainfall. The 30-day periodicity in the sunspot activity was significant. (author)

Solar activity and rainfall pattern in Tamil Nadu during the Northeast monsoon

Energy Technology Data Exchange (ETDEWEB)

Reddy, R S; Mukherjee, B K; Ramana Murty, Bh V [Indian Inst. of Tropical Meteorology, Pune

1976-12-01

An attempt is made to examine the association, of any, between the rainfall, in Tamil Nadu and sunspot activity and if so, whether similar periodicities are also present in the sunspot activity. The daily relative sunspot numbers for the period Oct.-Dec. during 1961-70 and the daily sunspot means for the period Oct.-Dec. 1889-1938, as well as the rainfall series for the period Oct.-Nov., during 1961-70 have been analysed by power spectrum. An anti-phase relation was noticed between the rainfall and the sunspot activity. The 15-day periodicity in the rainfall was significant. The sunspot activity also showed similar periodicities as rainfall. The 30-day periodicity in the sunspot activity was significant.

Umbral oscillations as a probe of sunspot

International Nuclear Information System (INIS)

Abdelatif, T.E.H.

1985-01-01

The interaction of the solar five-minute oscillations with a sunspot is thoroughly explored, both on observational and theoretical grounds. Simple theoretical models are developed in order to understand the observations of umbral oscillations. Observations made at the National Solar Observatory detected both the three-minute and five-minute umbral oscillations at photospheric heights. The three-minute oscillations were found to have a kinetic energy density six times higher in the photosphere than in the chromosphere and to be concentrated in the central part of the umbra, supporting the photospheric resonance theory for the three-minute umbral oscillations. The five-minute oscillations are attenuated in the umbra, which appears to act as a filter in selecting some of the peaks in the power spectrum of five-minute oscillations in the surrounding photosphere. The k-omega power spectrum of the umbral oscillations shows a shift of power to longer wavelengths. Theoretical models of the transmission of acoustic waves into a magnetic region explain both observed effects

Active Longitude and Coronal Mass Ejection Occurrences

International Nuclear Information System (INIS)

Gyenge, N.; Kiss, T. S.; Erdélyi, R.; Singh, T.; Srivastava, A. K.

2017-01-01

The spatial inhomogeneity of the distribution of coronal mass ejection (CME) occurrences in the solar atmosphere could provide a tool to estimate the longitudinal position of the most probable CME-capable active regions in the Sun. The anomaly in the longitudinal distribution of active regions themselves is often referred to as active longitude (AL). In order to reveal the connection between the AL and CME spatial occurrences, here we investigate the morphological properties of active regions. The first morphological property studied is the separateness parameter, which is able to characterize the probability of the occurrence of an energetic event, such as a solar flare or CME. The second morphological property is the sunspot tilt angle. The tilt angle of sunspot groups allows us to estimate the helicity of active regions. The increased helicity leads to a more complex buildup of the magnetic structure and also can cause CME eruption. We found that the most complex active regions appear near the AL and that the AL itself is associated with the most tilted active regions. Therefore, the number of CME occurrences is higher within the AL. The origin of the fast CMEs is also found to be associated with this region. We concluded that the source of the most probably CME-capable active regions is at the AL. By applying this method, we can potentially forecast a flare and/or CME source several Carrington rotations in advance. This finding also provides new information for solar dynamo modeling.

Active Longitude and Coronal Mass Ejection Occurrences

Energy Technology Data Exchange (ETDEWEB)

Gyenge, N.; Kiss, T. S.; Erdélyi, R. [Solar Physics and Space Plasmas Research Centre (SP2RC), School of Mathematics and Statistics, University of Sheffield Hounsfield Road, Hicks Building, Sheffield S3 7RH (United Kingdom); Singh, T.; Srivastava, A. K., E-mail: n.g.gyenge@sheffield.ac.uk [Department of Physics, Indian Institute of Technology (Banaras Hindu University), Varanasi (India)

2017-03-20

The spatial inhomogeneity of the distribution of coronal mass ejection (CME) occurrences in the solar atmosphere could provide a tool to estimate the longitudinal position of the most probable CME-capable active regions in the Sun. The anomaly in the longitudinal distribution of active regions themselves is often referred to as active longitude (AL). In order to reveal the connection between the AL and CME spatial occurrences, here we investigate the morphological properties of active regions. The first morphological property studied is the separateness parameter, which is able to characterize the probability of the occurrence of an energetic event, such as a solar flare or CME. The second morphological property is the sunspot tilt angle. The tilt angle of sunspot groups allows us to estimate the helicity of active regions. The increased helicity leads to a more complex buildup of the magnetic structure and also can cause CME eruption. We found that the most complex active regions appear near the AL and that the AL itself is associated with the most tilted active regions. Therefore, the number of CME occurrences is higher within the AL. The origin of the fast CMEs is also found to be associated with this region. We concluded that the source of the most probably CME-capable active regions is at the AL. By applying this method, we can potentially forecast a flare and/or CME source several Carrington rotations in advance. This finding also provides new information for solar dynamo modeling.

Active Longitude and Coronal Mass Ejection Occurrences

Science.gov (United States)

Gyenge, N.; Singh, T.; Kiss, T. S.; Srivastava, A. K.; Erdélyi, R.

2017-03-01

The spatial inhomogeneity of the distribution of coronal mass ejection (CME) occurrences in the solar atmosphere could provide a tool to estimate the longitudinal position of the most probable CME-capable active regions in the Sun. The anomaly in the longitudinal distribution of active regions themselves is often referred to as active longitude (AL). In order to reveal the connection between the AL and CME spatial occurrences, here we investigate the morphological properties of active regions. The first morphological property studied is the separateness parameter, which is able to characterize the probability of the occurrence of an energetic event, such as a solar flare or CME. The second morphological property is the sunspot tilt angle. The tilt angle of sunspot groups allows us to estimate the helicity of active regions. The increased helicity leads to a more complex buildup of the magnetic structure and also can cause CME eruption. We found that the most complex active regions appear near the AL and that the AL itself is associated with the most tilted active regions. Therefore, the number of CME occurrences is higher within the AL. The origin of the fast CMEs is also found to be associated with this region. We concluded that the source of the most probably CME-capable active regions is at the AL. By applying this method, we can potentially forecast a flare and/or CME source several Carrington rotations in advance. This finding also provides new information for solar dynamo modeling.

Absorption of acoustic waves by sunspots. II - Resonance absorption in axisymmetric fibril models

Science.gov (United States)

Rosenthal, C. S.

1992-01-01

Analytical calculations of acoustic waves scattered by sunspots which concentrate on the absorption at the magnetohydrodynamic Alfven resonance are extended to the case of a flux-tube embedded in a uniform atmosphere. The model is based on a flux-tubes of varying radius that are highly structured, translationally invariant, and axisymmetric. The absorbed fractional energy is determined for different flux-densities and subphotospheric locations with attention given to the effects of twist. When the flux is highly concentrated into annuli efficient absorption is possible even when the mean magnetic flux density is low. The model demonstrates low absorption at low azimuthal orders even in the presence of twist which generally increases the range of wave numbers over which efficient absorption can occur. Resonance absorption is concluded to be an efficient mechanism in monolithic sunspots, fibril sunspots, and plage fields.

On the determination of heliographic positions and rotation velocities of sunspots. Pt. 2

International Nuclear Information System (INIS)

Balthasar, H.

1983-01-01

Using sunspot positions of small sunspots observed at Debrecen and Locarno as well as positions of recurrent sunspots taken from the Greenwich Photoheliographic Results (1940-1976) the influence of the Wilson depression on the rotation velocities was investigated. It was found that the Wilson depression can be determined by minimizing errors of the rotation velocities or minimizing the differences of rotation velocities determined from disk passages and central meridian passages. The Wilson depressions found were between 765 km and 2500 km for the first sample while they were between 0 km and several 1000 km for the second sample. The averaged Wilson depression for the second sample is between 500 km and 965 km depending on the reduction method. A dependence of the Wilson depression on the age of the spots investigated seems not to exist. (orig.)

Latitude dependence of long-term geomagnetic activity and its solar wind drivers

Energy Technology Data Exchange (ETDEWEB)

Myllys, M. [Helsinki Univ. (Finland). Dept. of Physics; Partamies, N. [Finnish Meteorological Institute, Helsinki (Finland); University Centre in Svalbard, Longyearbyen (Norway). Dept. of Arctic Geophysics; Juusola, L. [Finnish Meteorological Institute, Helsinki (Finland)

2015-09-01

To validate the usage of global indices in studies of geomagnetic activity, we have examined the latitude dependence of geomagnetic variations in Fennoscandia and Svalbard from 1994 to 2010. Daily standard deviation (SD) values of the horizontal magnetic field have been used as a measure of the ground magnetic disturbance level.We found that the timing of the geomagnetic minimum depends on the latitude region: corresponding to the minimum of sunspot cycle 22 (in 1996), the geomagnetic minimum occurred between the geomagnetic latitudes 57-61 in 1996 and at the latitudes 64-67 in 1997, which are the average auroral oval latitudes. During sunspot cycle 23, all latitude regions experienced the minimum in 2009, a year after the sunspot minimum. These timing differences are due to the latitude dependence of the 10 s daily SD on the different solar wind drivers. In the latitude region of 64-67 , the impact of the high-speed solar wind streams (HSSs) on the geomagnetic activity is the most pronounced compared to the other latitude groups, while in the latitude region of 57-61 , the importance of the coronal mass ejections (CMEs) dominates. The geomagnetic activity maxima during ascending solar cycle phases are typically caused by CME activity and occur especially in the oval and sub-auroral regions. The strongest geomagnetic activity occurs during the descending solar cycle phases due to a mixture of CME and HSS activity. Closer to the solar minimum, less severe geomagnetic activity is driven by HSSs and mainly visible in the poleward part of the auroral region. According to our study, however, the timing of the geomagnetic activity minima (and maxima) in different latitude bands is different, due to the relative importance of different solar wind drivers at different latitudes.

Latitude dependence of long-term geomagnetic activity and its solar wind drivers

International Nuclear Information System (INIS)

Myllys, M.

2015-01-01

To validate the usage of global indices in studies of geomagnetic activity, we have examined the latitude dependence of geomagnetic variations in Fennoscandia and Svalbard from 1994 to 2010. Daily standard deviation (SD) values of the horizontal magnetic field have been used as a measure of the ground magnetic disturbance level.We found that the timing of the geomagnetic minimum depends on the latitude region: corresponding to the minimum of sunspot cycle 22 (in 1996), the geomagnetic minimum occurred between the geomagnetic latitudes 57-61 in 1996 and at the latitudes 64-67 in 1997, which are the average auroral oval latitudes. During sunspot cycle 23, all latitude regions experienced the minimum in 2009, a year after the sunspot minimum. These timing differences are due to the latitude dependence of the 10 s daily SD on the different solar wind drivers. In the latitude region of 64-67 , the impact of the high-speed solar wind streams (HSSs) on the geomagnetic activity is the most pronounced compared to the other latitude groups, while in the latitude region of 57-61 , the importance of the coronal mass ejections (CMEs) dominates. The geomagnetic activity maxima during ascending solar cycle phases are typically caused by CME activity and occur especially in the oval and sub-auroral regions. The strongest geomagnetic activity occurs during the descending solar cycle phases due to a mixture of CME and HSS activity. Closer to the solar minimum, less severe geomagnetic activity is driven by HSSs and mainly visible in the poleward part of the auroral region. According to our study, however, the timing of the geomagnetic activity minima (and maxima) in different latitude bands is different, due to the relative importance of different solar wind drivers at different latitudes.

LONG-TERM MEASUREMENTS OF SUNSPOT MAGNETIC TILT ANGLES

Energy Technology Data Exchange (ETDEWEB)

Li Jing [Department of Earth and Space Sciences, University of California at Los Angeles, Los Angeles, CA 90095-1567 (United States); Ulrich, Roger K., E-mail: jli@igpp.ucla.edu [Department of Physics and Astronomy, University of California at Los Angeles, Los Angeles, CA 90095-1567 (United States)

2012-10-20

Tilt angles of close to 30,600 sunspots are determined using Mount Wilson daily averaged magnetograms taken from 1974 to 2012, and SOHO/MDI magnetograms taken from 1996 to 2010. Within a cycle, more than 90% of sunspots have a normal polarity alignment along the east-west direction following Hale's law. The median tilts increase with increasing latitude (Joy's law) at a rate of {approx}0.{sup 0}5 per degree of latitude. Tilt angles of spots appear largely invariant with respect to time at a given latitude, but they decrease by {approx}0.{sup 0}9 per year on average, a trend that largely reflects Joy's law following the butterfly diagram. We find an asymmetry between the hemispheres in the mean tilt angles. On average, the tilts are greater in the Southern than in the Northern Hemisphere for all latitude zones, and the differences increase with increasing latitude.

Response of Solar Irradiance to Sunspot-area Variations

Science.gov (United States)

Dudok de Wit, T.; Kopp, G.; Shapiro, A.; Witzke, V.; Kretzschmar, M.

2018-02-01

One of the important open questions in solar irradiance studies is whether long-term variability (i.e., on timescales of years and beyond) can be reconstructed by means of models that describe short-term variability (i.e., days) using solar proxies as inputs. Preminger & Walton showed that the relationship between spectral solar irradiance and proxies of magnetic-flux emergence, such as the daily sunspot area, can be described in the framework of linear system theory by means of the impulse response. We significantly refine that empirical model by removing spurious solar-rotational effects and by including an additional term that captures long-term variations. Our results show that long-term variability cannot be reconstructed from the short-term response of the spectral irradiance, which questions the extension of solar proxy models to these timescales. In addition, we find that the solar response is nonlinear in a way that cannot be corrected simply by applying a rescaling to a sunspot area.

A SOLAR FLARE DISTURBING A LIGHT WALL ABOVE A SUNSPOT LIGHT BRIDGE

International Nuclear Information System (INIS)

Hou, Yijun; Zhang, Jun; Li, Ting; Yang, Shuhong; Li, Leping; Li, Xiaohong

2016-01-01

With the high-resolution data from the Interface Region Imaging Spectrograph , we detect a light wall above a sunspot light bridge in the NOAA active region (AR) 12403. In the 1330 Å slit-jaw images, the light wall is brighter than the ambient areas while the wall top and base are much brighter than the wall body, and it keeps oscillating above the light bridge. A C8.0 flare caused by a filament activation occurred in this AR with the peak at 02:52 UT on 2015 August 28, and the flare’s one ribbon overlapped the light bridge, which was the observational base of the light wall. Consequently, the oscillation of the light wall was evidently disturbed. The mean projective oscillation amplitude of the light wall increased from 0.5 to 1.6 Mm before the flare and decreased to 0.6 Mm after the flare. We suggest that the light wall shares a group of magnetic field lines with the flare loops, which undergo a magnetic reconnection process, and they constitute a coupled system. When the magnetic field lines are pushed upward at the pre-flare stage, the light wall turns to the vertical direction, resulting in the increase of the light wall’s projective oscillation amplitude. After the magnetic reconnection takes place, a group of new field lines with smaller scales are formed underneath the reconnection site, and the light wall inclines. Thus, the projective amplitude notably decrease at the post-flare stage.

A SOLAR FLARE DISTURBING A LIGHT WALL ABOVE A SUNSPOT LIGHT BRIDGE

Energy Technology Data Exchange (ETDEWEB)

Hou, Yijun; Zhang, Jun; Li, Ting; Yang, Shuhong; Li, Leping; Li, Xiaohong, E-mail: yijunhou@nao.cas.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

2016-10-01

With the high-resolution data from the Interface Region Imaging Spectrograph , we detect a light wall above a sunspot light bridge in the NOAA active region (AR) 12403. In the 1330 Å slit-jaw images, the light wall is brighter than the ambient areas while the wall top and base are much brighter than the wall body, and it keeps oscillating above the light bridge. A C8.0 flare caused by a filament activation occurred in this AR with the peak at 02:52 UT on 2015 August 28, and the flare’s one ribbon overlapped the light bridge, which was the observational base of the light wall. Consequently, the oscillation of the light wall was evidently disturbed. The mean projective oscillation amplitude of the light wall increased from 0.5 to 1.6 Mm before the flare and decreased to 0.6 Mm after the flare. We suggest that the light wall shares a group of magnetic field lines with the flare loops, which undergo a magnetic reconnection process, and they constitute a coupled system. When the magnetic field lines are pushed upward at the pre-flare stage, the light wall turns to the vertical direction, resulting in the increase of the light wall’s projective oscillation amplitude. After the magnetic reconnection takes place, a group of new field lines with smaller scales are formed underneath the reconnection site, and the light wall inclines. Thus, the projective amplitude notably decrease at the post-flare stage.

The Frequency-dependent Damping of Slow Magnetoacoustic Waves in a Sunspot Umbral Atmosphere

Energy Technology Data Exchange (ETDEWEB)

Prasad, S. Krishna; Jess, D. B. [Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, Belfast, BT7 1NN (United Kingdom); Doorsselaere, T. Van [Centre for mathematical Plasma Astrophysics, Mathematics Department, KU Leuven, Celestijnenlaan 200B bus 2400, B-3001 Leuven (Belgium); Verth, G. [School of Mathematics and Statistics, The University of Sheffield, Hicks Building, Hounsfield Road, Sheffield, S3 7RH (United Kingdom); Morton, R. J. [Department of Mathematics, Physics and Electrical Engineering, Northumbria University, Ellison Building, Newcastle upon Tyne, NE1 8ST (United Kingdom); Fedun, V. [Department of Automatic Control and Systems Engineering, University of Sheffield, Sheffield, S1 3JD (United Kingdom); Erdélyi, R. [Solar Physics and Space Plasma Research Centre (SP2RC), School of Mathematics and Statistics, University of Sheffield, Sheffield S3 7RH (United Kingdom); Christian, D. J., E-mail: krishna.prasad@qub.ac.uk [Department of Physics and Astronomy, California State University Northridge, Northridge, CA 91330 (United States)

2017-09-20

High spatial and temporal resolution images of a sunspot, obtained simultaneously in multiple optical and UV wavelengths, are employed to study the propagation and damping characteristics of slow magnetoacoustic waves up to transition region heights. Power spectra are generated from intensity oscillations in sunspot umbra, across multiple atmospheric heights, for frequencies up to a few hundred mHz. It is observed that the power spectra display a power-law dependence over the entire frequency range, with a significant enhancement around 5.5 mHz found for the chromospheric channels. The phase difference spectra reveal a cutoff frequency near 3 mHz, up to which the oscillations are evanescent, while those with higher frequencies propagate upward. The power-law index appears to increase with atmospheric height. Also, shorter damping lengths are observed for oscillations with higher frequencies suggesting frequency-dependent damping. Using the relative amplitudes of the 5.5 mHz (3 minute) oscillations, we estimate the energy flux at different heights, which seems to decay gradually from the photosphere, in agreement with recent numerical simulations. Furthermore, a comparison of power spectra across the umbral radius highlights an enhancement of high-frequency waves near the umbral center, which does not seem to be related to magnetic field inclination angle effects.

Strong Transverse Photosphere Magnetic Fields and Twist in Light Bridge Dividing Delta Sunspot of Active Region 12673

OpenAIRE

Wang, Haimin; Yurchyshyn, Vasyl; Liu, Chang; Ahn, Kwangsu; Toriumi, Shin; Cao, Wenda

2018-01-01

Solar Active Region (AR) 12673 is the most flare productive AR in the solar cycle 24. It produced four X-class flares including the X9.3 flare on 06 September 2017 and the X8.2 limb event on 10 September. Sun and Norton (2017) reported that this region had an unusual high rate of flux emergence, while Huang et al. (2018) reported that the X9.3 flare had extremely strong white-light flare emissions. Yang at al. (2017) described the detailed morphological evolution of this AR. In this report, w...

STUDY OF THE POYNTING FLUX IN ACTIVE REGION 10930 USING DATA-DRIVEN MAGNETOHYDRODYNAMIC SIMULATION

International Nuclear Information System (INIS)

Fan, Y. L.; Wang, H. N.; He, H.; Zhu, X. S.

2011-01-01

Powerful solar flares are closely related to the evolution of magnetic field configuration on the photosphere. We choose the Poynting flux as a parameter in the study of magnetic field changes. We use time-dependent multidimensional MHD simulations around a flare occurrence to generate the results, with the temporal variation of the bottom boundary conditions being deduced from the projected normal characteristic method. By this method, the photospheric magnetogram could be incorporated self-consistently as the bottom condition of data-driven simulations. The model is first applied to a simulation datum produced by an emerging magnetic flux rope as a test case. Then, the model is used to study NOAA AR 10930, which has an X3.4 flare, the data of which has been obtained by the Hinode/Solar Optical Telescope on 2006 December 13. We compute the magnitude of Poynting flux (S total ), radial Poynting flux (S z ), a proxy for ideal radial Poynting flux (S proxy ), Poynting flux due to plasma surface motion (S sur ), and Poynting flux due to plasma emergence (S emg ) and analyze their extensive properties in four selected areas: the whole sunspot, the positive sunspot, the negative sunspot, and the strong-field polarity inversion line (SPIL) area. It is found that (1) the S total , S z , and S proxy parameters show similar behaviors in the whole sunspot area and in the negative sunspot area. The evolutions of these three parameters in the positive area and the SPIL area are more volatile because of the effect of sunspot rotation and flux emergence. (2) The evolution of S sur is largely influenced by the process of sunspot rotation, especially in the positive sunspot. The evolution of S emg is greatly affected by flux emergence, especially in the SPIL area.

New reconstruction of the sunspot group numbers since 1739 using direct calibration and "backbone" methods

Science.gov (United States)

Chatzistergos, Theodosios; Usoskin, Ilya G.; Kovaltsov, Gennady A.; Krivova, Natalie A.; Solanki, Sami K.

2017-06-01

Context. The group sunspot number (GSN) series constitute the longest instrumental astronomical database providing information on solar activity. This database is a compilation of observations by many individual observers, and their inter-calibration has usually been performed using linear rescaling. There are multiple published series that show different long-term trends for solar activity. Aims: We aim at producing a GSN series, with a non-linear non-parametric calibration. The only underlying assumptions are that the differences between the various series are due to different acuity thresholds of the observers, and that the threshold of each observer remains constant throughout the observing period. Methods: We used a daisy chain process with backbone (BB) observers and calibrated all overlapping observers to them. We performed the calibration of each individual observer with a probability distribution function (PDF) matrix constructed considering all daily values for the overlapping period with the BB. The calibration of the BBs was carried out in a similar manner. The final series was constructed by merging different BB series. We modelled the propagation of errors straightforwardly with Monte Carlo simulations. A potential bias due to the selection of BBs was investigated and the effect was shown to lie within the 1σ interval of the produced series. The exact selection of the reference period was shown to have a rather small effect on our calibration as well. Results: The final series extends back to 1739 and includes data from 314 observers. This series suggests moderate activity during the 18th and 19th century, which is significantly lower than the high level of solar activity predicted by other recent reconstructions applying linear regressions. Conclusions: The new series provides a robust reconstruction, based on modern and non-parametric methods, of sunspot group numbers since 1739, and it confirms the existence of the modern grand maximum of solar

FORMATION OF CORONAL HOLES ON THE ASHES OF ACTIVE REGIONS

International Nuclear Information System (INIS)

Karachik, Nina V.; Pevtsov, Alexei A.; Abramenko, Valentyna I.

2010-01-01

We investigate the formation of isolated non-polar coronal holes (CHs) on the remnants of decaying active regions (ARs) at the minimum/early ascending phase of sunspot activity. We follow the evolution of four bipolar ARs and measure several parameters of their magnetic fields including total flux, imbalance, and compactness. As regions decay, their leading and following polarities exhibit different dissipation rates: loose polarity tends to dissipate faster than compact polarity. As a consequence, we see a gradual increase in flux imbalance inside a dissipating bipolar region, and later a formation of a CH in place of more compact magnetic flux. Out of four cases studied in detail, two CHs had formed at the following polarity of the decaying bipolar AR, and two CHs had developed in place of the leading polarity field. All four CHs contain a significant fraction of magnetic field of their corresponding AR. Using potential field extrapolation, we show that the magnetic field lines of these CHs were closed on the polar CH at the North, which at the time of the events was in imbalance with the polar CH at the South. This topology suggests that the observed phenomenon may play an important role in transformation of toroidal magnetic field to poloidal field, which is a key step in transitioning from an old solar cycle to a new one. The timing of this observed transition may indicate the end of solar cycle 23 and the beginning of cycle 24.

Occurrences of flares with type II and IV radio events in interacting sunspot groups in the course of revolutions

International Nuclear Information System (INIS)

Klimes, J.; Krivsky, L.

1984-01-01

Using data from 11-year solar cycle No. 20, it was found that flares with type II radio bursts are more than twice as frequent and flares with type IV bursts nearly twice as frequent in sunspot groups which developed close to each other or which merged in the course of revolutions than in isolated sunspot groups. With both types the occurrence of these flares is concentrated in the revolution of the so-called sunspot group interaction (their approximation, merging). (author)

On the correlation of longitudinal and latitudinal motions of sunspots

International Nuclear Information System (INIS)

Gilman, P.A.

1984-01-01

Using new measurements of positions of individual sunspots and sunspot groups obtained from 62 years of the Mt. Wilson white-light plate collection, we have recomputed the correlation between longitude and latitude motion. Our results for groups are similar to those of Ward (1965a) computed from the Greenwich record, but for individual spots the covariance is reduced by a factor of about 3 from the Ward values, though still of the same sign and still statistically significant. We conclude that there is a real correlation between longitude and latitude movement of individual spots, implying angular momentum transport toward the equator as inferred by Ward. The two thirds reduction in the covariance for individual spots as opposed to groups is probably due to certain properties of spot groups, as first pointed out in an unpublished manuscript by Leighton. (orig.)

The chromosphere above a δ-sunspot in the presence of fan-shaped jets

Science.gov (United States)

Robustini, Carolina; Leenaarts, Jorrit; de la Cruz Rodríguez, Jaime

2018-01-01

Context. Delta-sunspots are known to be favourable locations for fast and energetic events like flares and coronal mass ejections. The photosphere of this sunspot type has been thoroughly investigated in the past three decades. The atmospheric conditions in the chromosphere are not as well known, however. Aims: This study is focused on the chromosphere of a δ-sunspot that harbours a series of fan-shaped jets in its penumbra. The aim of this study is to establish the magnetic field topology and the temperature distribution in the presence of jets in the photosphere and the chromosphere. Methods: We use data from the Swedish 1m Solar Telescope (SST) and the Solar Dynamics Observatory. We invert the spectropolarimetric Fe I 6302 Å and Ca II 8542 Å data from the SST using the non-LTE inversion code NICOLE to estimate the magnetic field configuration, temperature, and velocity structure in the chromosphere. Results: A loop-like magnetic structure is observed to emerge in the penumbra of the sunspot. The jets are launched from this structure. Magnetic reconnection between this emerging field and the pre-existing vertical field is suggested by hot plasma patches on the interface between the two fields. The height at which the reconnection takes place is located between log τ500 = -2 and log τ500 = -3. The magnetic field vector and the atmospheric temperature maps show a stationary configuration during the whole observation. Movies associated to Figs. 3-5 are available at http://www.aanda.org

Simultaneous Observations of p-mode Light Walls and Magnetic Reconnection Ejections above Sunspot Light Bridges

Energy Technology Data Exchange (ETDEWEB)

Hou, Yijun; Zhang, Jun; Li, Ting; Yang, Shuhong; Li, Xiaohong, E-mail: yijunhou@nao.cas.cn, E-mail: zjun@nao.cas.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

2017-10-10

Recent high-resolution observations from the Interface Region Imaging Spectrograph reveal bright wall-shaped structures in active regions (ARs), especially above sunspot light bridges. Their most prominent feature is the bright oscillating front in the 1400/1330 Å channel. These structures are named light walls and are often interpreted to be driven by p-mode waves. Above the light bridge of AR 12222 on 2014 December 06, we observed intermittent ejections superimposed on an oscillating light wall in the 1400 Å passband. At the base location of each ejection, the emission enhancement was detected in the Solar Dynamics Observatory 1600 Å channel. Thus, we suggest that in wall bases (light bridges), in addition to the leaked p-mode waves consistently driving the oscillating light wall, magnetic reconnection could happen intermittently at some locations and eject the heated plasma upward. Similarly, in the second event occurring in AR 12371 on 2015 June 16, a jet was simultaneously detected in addition to the light wall with a wave-shaped bright front above the light bridge. At the footpoint of this jet, lasting brightening was observed, implying magnetic reconnection at the base. We propose that in these events, two mechanisms, p-mode waves and magnetic reconnection, simultaneously play roles in the light bridge, and lead to the distinct kinetic features of the light walls and the ejection-like activities, respectively. To illustrate the two mechanisms and their resulting activities above light bridges, in this study we present a cartoon model.

Effect of solar flare ans sunspot numbers on the intensity of 5577A line in the night airglow

International Nuclear Information System (INIS)

Kundu, N.; Ghosh, S.N.

1981-01-01

The effects of solar flare and sunspot number on the intensity of 5577 A line emission are presented. The time lag between the occurrence of a flare and the enhancement of 5577 A line intensity is determined by observing the intensity of the line on three successive nights- the night preceding the flare and the two nights following it. The velocity of the solar corpuscles is then calculated. The value obtained at Allahabad (2400 Km/sec) is in agreement with the De Jager's prediction for explosive flare. Day-to-day analyses of the observations taken at Allahabad exhibit high correlation of the intensity of 5577 A line emission with sunspot number. Also, correlation is found for the intensity of 5577 A with the change in sunspot number (DELTA R) from the day preceding the night of observation to the day following it. The intensity appears to vary with the magnetic field produced by the sunspot and not with the spot area. (author)

REGULARITY OF THE NORTH–SOUTH ASYMMETRY OF SOLAR ACTIVITY: REVISITED

International Nuclear Information System (INIS)

Zhang, J.; Feng, W.

2015-01-01

Extended time series of Solar Activity Indices (ESAI) extended the Greenwich series of sunspot area from the year 1874 back to 1821. The ESAI's yearly sunspot area in the northern and southern hemispheres from 1821 to 2013 is utilized to investigate characteristics of the north–south hemispherical asymmetry of sunspot activity. Periodical behavior of about 12 solar cycles is also confirmed from the ESAI data set to exist in dominant hemispheres, linear regression lines of yearly asymmetry values, and cumulative counts of yearly sunspot areas in the hemispheres for solar cycles. The period is also inferred to appear in both the cumulative difference in the yearly sunspot areas in the hemispheres over the entire time interval and in its statistical Student's t-test. The hemispherical bias of sunspot activity should be regarded as an impossible stochastic phenomenon over a long time period

TIME DISTRIBUTIONS OF LARGE AND SMALL SUNSPOT GROUPS OVER FOUR SOLAR CYCLES

International Nuclear Information System (INIS)

Kilcik, A.; Yurchyshyn, V. B.; Abramenko, V.; Goode, P. R.; Cao, W.; Ozguc, A.; Rozelot, J. P.

2011-01-01

Here we analyze solar activity by focusing on time variations of the number of sunspot groups (SGs) as a function of their modified Zurich class. We analyzed data for solar cycles 20-23 by using Rome (cycles 20 and 21) and Learmonth Solar Observatory (cycles 22 and 23) SG numbers. All SGs recorded during these time intervals were separated into two groups. The first group includes small SGs (A, B, C, H, and J classes by Zurich classification), and the second group consists of large SGs (D, E, F, and G classes). We then calculated small and large SG numbers from their daily mean numbers as observed on the solar disk during a given month. We report that the time variations of small and large SG numbers are asymmetric except for solar cycle 22. In general, large SG numbers appear to reach their maximum in the middle of the solar cycle (phases 0.45-0.5), while the international sunspot numbers and the small SG numbers generally peak much earlier (solar cycle phases 0.29-0.35). Moreover, the 10.7 cm solar radio flux, the facular area, and the maximum coronal mass ejection speed show better agreement with the large SG numbers than they do with the small SG numbers. Our results suggest that the large SG numbers are more likely to shed light on solar activity and its geophysical implications. Our findings may also influence our understanding of long-term variations of the total solar irradiance, which is thought to be an important factor in the Sun-Earth climate relationship.

Cyclotron Line in Solar Microwave Radiation by Radio Telescope RATAN-600 Observations of the Solar Active Region NOAA 12182

Science.gov (United States)

Peterova, N. G.; Topchilo, N. A.

2017-12-01

This paper presents the results of observation of a rare phenomenon—a narrowband increase in the brightness of cyclotron radiation of one of the structural details of a radio source located in the solar corona above the solar active region NOAA 12182 in October 2014 at a frequency of 4.2 ± 0.1 GHz. The brightness of radiation in the maximum of the phenomenon has reached 10 MK; its duration was equal to 3 s. The exact location of the source of the narrowband cyclotron radiation is indicated: it is a corona above a fragmented (4-nuclear) sunspot, on which a small UV flare loop was closed.

Distribution of electric currents in sunspots from photosphere to corona

Energy Technology Data Exchange (ETDEWEB)

Gosain, Sanjay [National Solar Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Démoulin, Pascal [Observatoire de Paris, LESIA, UMR 8109 (CNRS), F-92195 Meudon Principal Cedex (France); López Fuentes, Marcelo [Instituto de Astronomía y Física del Espacio (IAFE), UBA-CONICET, CC. 67, Suc. 28 Buenos Aires 1428 (Argentina)

2014-09-20

We present a study of two regular sunspots that exhibit nearly uniform twist from the photosphere to the corona. We derive the twist parameter in the corona and in the chromosphere by minimizing the difference between the extrapolated linear force-free field model field lines and the observed intensity structures in the extreme-ultraviolet images of the Sun. The chromospheric structures appear more twisted than the coronal structures by a factor of two. Further, we derive the vertical component of electric current density, j{sub z} , using vector magnetograms from the Hinode Solar Optical Telescope (SOT). The spatial distribution of j{sub z} has a zebra pattern of strong positive and negative values owing to the penumbral fibril structure resolved by Hinode/SOT. This zebra pattern is due to the derivative of the horizontal magnetic field across the thin fibrils; therefore, it is strong and masks weaker currents that might be present, for example, as a result of the twist of the sunspot. We decompose j{sub z} into the contribution due to the derivatives along and across the direction of the horizontal field, which follows the fibril orientation closely. The map of the tangential component has more distributed currents that are coherent with the chromospheric and coronal twisted structures. Moreover, it allows us to map and identify the direct and return currents in the sunspots. Finally, this decomposition of j{sub z} is general and can be applied to any vector magnetogram in order to better identify the weaker large-scale currents that are associated with coronal twisted/sheared structures.

SUNSPOT AND STARSPOT LIFETIMES IN A TURBULENT EROSION MODEL

Energy Technology Data Exchange (ETDEWEB)

Litvinenko, Yuri E. [Department of Mathematics, University of Waikato, P. B. 3105, Hamilton (New Zealand); Wheatland, M. S. [Sydney Institute for Astronomy, School of Physics, The University of Sydney, NSW 2006 (Australia)

2017-01-10

Quantitative models of sunspot and starspot decay predict the timescale of magnetic diffusion and may yield important constraints in stellar dynamo models. Motivated by recent measurements of starspot lifetimes, we investigate the disintegration of a magnetic flux tube by nonlinear diffusion. Previous theoretical studies are extended by considering two physically motivated functional forms for the nonlinear diffusion coefficient D : an inverse power-law dependence D ∝ B {sup −ν} and a step-function dependence of D on the magnetic field magnitude B . Analytical self-similar solutions are presented for the power-law case, including solutions exhibiting “super fast” diffusion. For the step-function case, the heat-balance integral method yields approximate solutions, valid for moderately suppressed diffusion in the spot. The accuracy of the resulting solutions is confirmed numerically, using a method which provides an accurate description of long-time evolution by imposing boundary conditions at infinite distance from the spot. The new models may allow insight into the differences and similarities between sunspots and starspots.

STOCHASTIC DESCRIPTION OF THE HIGH-FREQUENCY CONTENT OF DAILY SUNSPOTS AND EVIDENCE FOR REGIME CHANGES

International Nuclear Information System (INIS)

Shapoval, A.; Le Mouël, J.-L.; Courtillot, V.; Shnirman, M.

2015-01-01

The irregularity index λ is applied to the high-frequency content of daily sunspot numbers ISSN. This λ is a modification of the standard maximal Lyapunov exponent. It is computed here as a function of embedding dimension m, within four-year time windows centered at the maxima of Schwabe cycles. The λ(m) curves form separate clusters (pre-1923 and post-1933). This supports a regime transition and narrows its occurrence to cycle 16, preceding the growth of activity leading to the Modern Maximum. The two regimes are reproduced by a simple autoregressive process AR(1), with the mean of Poisson noise undergoing 11 yr modulation. The autocorrelation a of the process (linked to sunspot lifetime) is a ≈ 0.8 for 1850-1923 and ≈0.95 for 1933-2013. The AR(1) model suggests that groups of spots appear with a Poisson rate and disappear at a constant rate. We further applied the irregularity index to the daily sunspot group number series for the northern and southern hemispheres, provided by the Greenwich Royal Observatory (RGO), in order to study a possible desynchronization. Correlations between the north and south λ(m) curves vary quite strongly with time and indeed show desynchronization. This may reflect a slow change in the dimension of an underlying dynamical system. The ISSN and RGO series of group numbers do not imply an identical mechanism, but both uncover a regime change at a similar time. Computation of the irregularity index near the maximum of cycle 24 will help in checking whether yet another regime change is under way

Automated Sunspot Detection and Classification Using SOHO/MDI Imagery

Science.gov (United States)

2015-03-01

to the geocentric North). 3. Focus and size of the solar disk is adjusted to fit an 18 cm diameter circle on the worksheet. 4. Analyst hand draws the...General Nature of the Sunspot,” The Astrophysical Journal 230, 905–913 (1979). 14. Wheatland, M. S., “A Bayesian Approach to Solar Flare Prediction,” The

Preliminary results from the orbiting solar observatory 8: Persistent velocity fields in the chromosphere and transition region

International Nuclear Information System (INIS)

Lites, B.W.; Bruner, E.C. Jr.; Chipman, E.G.; Shine, R.A.; Rottman, G.J.; White, O.R.; Athay, R.G.

1976-01-01

Velocity images, or tachograms, of the solar chromosphere and chromosphere-corona transition region were made by measuring the Si II 1816.93 A chromospheric line and the Si IV 1393.8 A transition region line with the University of Colorado spectrometer aboard OSO-8. Persistent flows are indicated in both active and quiet regions of the solar atmosphere. In quiet regions, areas of enhanced emission (the chromospheric network) are apparently systematically redshifted with respect to the areas of lower intensity. This correlation does not hold in active regions, where long-lived downflows into sunspots have been observed

3-color photometry of a sunspot using speckle masking techniques

NARCIS (Netherlands)

Wiehr, E.; Sütterlin, P.

1998-01-01

A three-colour photometry is used to deduce the temperature of sunspot fine-structures. Using the Speckle-Masking method for image restoration, the resulting images (one per colour and burst) have a spatial resolution only limited by the telescope's aperture, i.e. 95km (blue), 145 km (red) and

The Extreme Solar Activity during October–November 2003 K. M. ...

Indian Academy of Sciences (India)

between occurrence of the abnormal activities of big sunspot groups that ... better statistics, we add the data of the sunspot positional measurements obtained from the ... Ai are the area values of the sunspot group for i number of observations.

On proton events of different solar activity cycles

International Nuclear Information System (INIS)

Sattarov, I.; Sherdanov, Ch.; Sattarov, B.

1997-01-01

In solar activity cycle N21 and N22 the latitude distribution of the proton large flares and sunspot groups is being studied. It was found that higher proton activity of cycle N22 is connected with its higher latitude sunspot activity (author)

Questioning the Influence of Sunspots on Amazon Hydrology: Even a Broken Clock Tells the Right Time Twice a Day

Science.gov (United States)

Baker, J. C. A.; Gloor, M.; Boom, A.; Neill, D. A.; Cintra, B. B. L.; Clerici, S. J.; Brienen, R. J. W.

2018-02-01

It was suggested in a recent article that sunspots drive decadal variation in Amazon River flow. This conclusion was based on a novel time series decomposition method used to extract a decadal signal from the Amazon River record. We have extended this analysis back in time, using a new hydrological proxy record of tree ring oxygen isotopes (δ18OTR). Consistent with the findings of Antico and Torres, we find a positive correlation between sunspots and the decadal δ18OTR cycle from 1903 to 2012 (r = 0.60, p r = -0.30, p = 0.11, 1799-1902). This result casts considerable doubt over the mechanism by which sunspots are purported to influence Amazon hydrology.

Solar spectral irradiance variability of some chromospheric emission lines through the solar activity cycles 21-23

Directory of Open Access Journals (Sweden)

Göker Ü.D.

2017-01-01

Full Text Available A study of variations of solar spectral irradiance (SSI in the wave-length ranges 121.5 nm-300.5 nm for the period 1981-2009 is presented. We used various data for ultraviolet (UV spectral lines and international sunspot number (ISSN from interactive data centers such as SME (NSSDC, UARS (GDAAC, SORCE (LISIRD and SIDC, respectively. We reduced these data by using the MATLsoftware package. In this respect, we revealed negative correlations of intensities of UV (289.5 nm-300.5 nm spectral lines originating in the solar chromosphere with the ISSN index during the unusually prolonged minimum between the solar activity cycles (SACs 23 and 24. We also compared our results with the variations of solar activity indices obtained by the ground-based telescopes. Therefore, we found that plage regions decrease while facular areas are increasing in SAC 23. However, the decrease in plage regions is seen in small sunspot groups (SGs, contrary to this, these regions in large SGs are comparable to previous SACs or even larger as is also seen in facular areas. Nevertheless, negative correlations between ISSN and SSI data indicate that these variations are in close connection with the classes of sunspots/SGs, faculae and plage regions. Finally, we applied the time series analysis of spectral lines corresponding to the wavelengths 121.5 nm-300.5 nm and made comparisons with the ISSN data. We found an unexpected increase in the 298.5 nm line for the Fe II ion. The variability of Fe II ion 298.5 nm line is in close connection with the facular areas and plage regions, and the sizes of these solar surface indices play an important role for the SSI variability, as well. So, we compared the connection between the sizes of faculae and plage regions, sunspots/SGs, chemical elements and SSI variability. Our future work will be the theoretical study of this connection and developing of a corresponding model.

Oscillations in sunspot umbras due to trapped Alfven waves excited by overstability

International Nuclear Information System (INIS)

Uchida, Yutaka; Sakurai, Takashi.

1975-01-01

Oscillations observed in sunspot umbras are interpreted as a vertical motion in the atmosphere induced by a standing Alfven wave trapped in the region between the overstable layer under the photosphere and the chromosphere-corona transition layer. The Alfven wave motion is considered to be excited by the overstable convection occurring at the bottom of the abovementioned oscillating layer, and waves with special frequencies are selected as eigen-mode waves standing in the ''cavity,'' while other waves which are out of phase with themselves after reflections will disappear. It is shown by solving the eigen-value problem that the fundamental eigen frequency falls in a range around 0.04 rad s -1 (corresponding to 140-180 s) for the condition in the umbra of a typical spot, and also that the eigen frequencies do not depend greatly on the circumstantial physical or geometric parameters of the model atmosphere, such as the temperature in the layer, or the height of the transition layer, etc. The eigen frequencies, however, depend on the Alfven velocity at the base of the oscillating layer (or at the top of the overstable layer), but the latter quantity, which represents the stiffness of the magnetic tube of force against the overturning motion, takes roughly a common value for different sunspots according to SAVAGE's (1969) stability analysis of the umbral atmosphere against thermal convection, and thus gives a comparatively narrow range of resonant frequencies. In addition to the selection mechanism for oscillations of 140-180-s period, some other aspects of the oscillation, such as the relation to the running penumbral waves, are discussed. (auth.)

Worldwide variation in atmospheric noise intensities with sunspot number: an in-depth look at the 20 to 24 hour seasonal time block

International Nuclear Information System (INIS)

Joglekar, P.J.; Sathiamurthy, T.S.

1975-01-01

Comparisons of the variation of atmospheric radio noise intensities for 20 to 24 hr to sunspot numbers have been completed. Statistical dependence between the noise intensities and sunspot numbers was found for different seasons at a number of frequencies for many locations in the global network of ARN-2 noise recorders. The noise intensities generally tended to decrease with sunspot number in the range from 50 kHz to 5 MHz, which is presumed to be due to increases in residual ionospheric absorption during nighttime. At frequencies greater than 5 MHz, noise intensities increased with sunspot number in many cases, which would be expected from our present knowledge of ionospheric behavior in the HF range. By convention, CCIR treats year-to-year variation in the noise intensities as random and includes them in the prediction uncertainty sigma /sub Fam/ (for which one value is given at a frequency for a seasonal time block for all locations) in system performance evaluation. An error analysis on a global basis shows that a large portion of the year-to-year variability is due to sunspot variation. This suggests the possibility of improved noise estimates. (auth)

Observations of Running Penumbral Waves Emerging in a Sunspot

Science.gov (United States)

Priya, T. G.; Wenda, Cao; Jiangtao, Su; Jie, Chen; Xinjie, Mao; Yuanyong, Deng; Robert, Erdélyi

2018-01-01

We present results from the investigation of 5 minute umbral oscillations in a single-polarity sunspot of active region NOAA 12132. The spectra of TiO, Hα, and 304 Å are used for corresponding atmospheric heights from the photosphere to lower corona. Power spectrum analysis at the formation height of Hα – 0.6 Å to the Hα center resulted in the detection of 5 minute oscillation signals in intensity interpreted as running waves outside the umbral center, mostly with vertical magnetic field inclination >15°. A phase-speed filter is used to extract the running wave signals with speed v ph > 4 km s‑1, from the time series of Hα – 0.4 Å images, and found twenty-four 3 minute umbral oscillatory events in a duration of one hour. Interestingly, the initial emergence of the 3 minute umbral oscillatory events are noticed closer to or at umbral boundaries. These 3 minute umbral oscillatory events are observed for the first time as propagating from a fraction of preceding running penumbral waves (RPWs). These fractional wavefronts rapidly separate from RPWs and move toward the umbral center, wherein they expand radially outwards suggesting the beginning of a new umbral oscillatory event. We found that most of these umbral oscillatory events develop further into RPWs. We speculate that the waveguides of running waves are twisted in spiral structures and hence the wavefronts are first seen at high latitudes of umbral boundaries and later at lower latitudes of the umbral center.

The tenth European regional astronomy meeting of the IAU

International Nuclear Information System (INIS)

1987-01-01

The conference met in 13 sessions. Session 1: ''Development of active solar regions'' included papers on sunspots, the photometry thereof, the diagnostics of radio waves of active solar regions, etc. Session 2: ''The complex of interplanetary bodies'' included papers on interplanetary dust, meteors, asteroids and comets. Session 3 dealt with resonance in the solar system. Papers presented in the session ''Structure of galaxies and star formation'' dealt with the problems of the development of stars and galaxies and their properties immediately after formation. The session: ''Rapid variability of single, binary and multiple stars'' contained papers on star observation and star activity. In other sessions participants heard papers on ultraviolet star spectra, cosmology and the formation of galaxies, high-energy astrophysics, active extragalactic objects and binary stars. (E.S.)

Fine structure in sunspots. IV. Penumbral grains in speckle reconstucted images

Czech Academy of Sciences Publication Activity Database

Sobotka, Michal; Suetterlin, P.

2001-01-01

Roč. 380, č. 2 (2001), s. 714-718 ISSN 0004-6361 R&D Projects: GA AV ČR KSK2043105; GA AV ČR IAA3003903 Institutional research plan: CEZ:AV0Z1003909 Keywords : sun * sunspots Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 2.790, year: 2000

Are climatological correlations with the Hale double sunspot cycle meaningful

International Nuclear Information System (INIS)

Goldberg, R.A.; Herman, J.R.

1975-09-01

A sunspot cycle which may have been subject to a predicted phase reversal between 1800 and 1880 A.D. is discussed. Several climatological parameters normally correlated with this cycle are examined and do not exhibit a corresponding phase reversal during this period. It is proposed that this apparent discrepency can be resolved by suitable observations during the upcoming half decade

EUV observations of the active Sun from the Havard experiment on ATM

International Nuclear Information System (INIS)

Noyes, R.W.; Foukal, P.V.; Huber, M.C.E.; Reeves, E.M.; Schmahl, E.J.; Timothy, J.G.; Vernazza, J.E.; Withbroe, G.L.

1975-01-01

The authors review some preliminary results from the Harvard College Observatory Extreme Ultraviolet Spectroheliometer on ATM that pertain to solar activity. The results reviewed are described in more detail in other papers referred to in the text. They first describe the instrument and its capabilities, and then turm to results on active regions, sunspots, flares, EUV bright points, coronal holes, and prominences. (Auth.)

Temperature mapping of sunspots and pores from speckle reconstructed three colour photometry

NARCIS (Netherlands)

Sütterlin, P.; Wiehr, E.

1998-01-01

The two-dimensional temperature distribution in a highly structured sunspot and in two small umbrae is determined from a three-colour photometry in narrow spectral continua. Disturbing influences from the earth’s atmosphere are removed by speckle masking techniques, yielding a spatial resolution

On Solar Granulations, Limb Darkening, and Sunspots: Brief Insights in Remembrance of Father Angelo Secchi

Directory of Open Access Journals (Sweden)

Robitaille P.-M.

2011-07-01

Full Text Available Father Angelo Secchi used the existence of solar granulation as a central line of rea- soning when he advanced that the Sun was a gaseous body with a photosphere contain- ing incandescent particulate matter (Secchi A. Sulla Struttura della Fotosfera Solare. Bullettino Meteorologico dell’Osservatorio del Collegio Romano , 30 November 1864, v.3(11, 1–3. Secchi saw the granules as condensed matter emitting the photospheric spectrum, while the darkened intergranular lanes conveyed the presence of a gaseous solar interior. Secchi also considered the nature of sunspots and limb darkening. In the context of modern solar models, opacity arguments currently account for the emis- sive properties of the photosphere. Optical depth is thought to explain limb darkening. Both temperature variations and magnetic fields are invoked to justify the weakened emissivities of sunspots, even though the presence of static magnetic fields in materi- als is not usually associated with modified emissivity. Conversely, within the context of a liquid metallic hydrogen solar model, the appearance of granules, limb darkening, and sunspots can be elegantly understood through the varying directional emissivity of condensed matter. A single explanation is applicable to all three phenomena. Granular contrast can be directly associated with the generation of limb darkening. Depending on size, granules can be analyzed by considering Kolmogoroff’s formulations and B ́ enard convection, respectively, both of which were observed using incompressible liquids, not gases. Granules follow the 2-dimensional space filling laws of Aboav-Weiner and Lewis. Their adherence to these structural laws provides supportive evidence that the granular surface of the Sun represents elements which can only be constructed from condensed matter. A gaseous Sun cannot be confined to a 2-dimensional framework. Mesogranules, supergranules, and giant cells constitute additional entities which further

The Temperature - Magnetic Field Relation in Observed and Simulated Sunspots

Czech Academy of Sciences Publication Activity Database

Sobotka, Michal; Rezaei, R.

2017-01-01

Roč. 292, č. 12 (2017), 188/1-188/12 ISSN 0038-0938 R&D Projects: GA ČR(CZ) GA14-04338S; GA MŠk(CZ) 7E13003 EU Projects: European Commission(XE) 312495 - SOLARNET Institutional support: RVO:67985815 Keywords : sunspots * magnetic fields * comparison Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics OBOR OECD: Astronomy (including astrophysics,space science) Impact factor: 2.682, year: 2016

Ten cycles of solar and geomagnetic activity

International Nuclear Information System (INIS)

Legrand, J.P.

1981-01-01

Series of 110 years of sunspot numbers and indices of geomagnetic activity are used with 17 years of solar wind data in order to study through solar cycles both stream and shock event solar activity. According to their patterns on Bartels diagrams of geomagnetic indices, stable wind streams and transient solar activities are separated from each other. Two classes of stable streams are identified: equatorial streams occurring sporadically, for several months, during the main phase of sunspot cycles and both polar streams established, for several years, at each cycle, before sunspot minimum. Polar streams are the first activity of solar cycles. For study of the relationship between transient geomagnetic phenomena and sunspot activity, we raise the importance of the contribution, at high spot number, of severe storms and, at low spot number, of short lived and unstable streams. Solar wind data are used to check and complete the above results. As a conclusion, we suggest a unified scheme of solar activity evolution with a starting point every eleventh year, a total duration of 17 years and an overlapping of 6 years between the first and the last phase of both successive series of phenomena: first, from polar field reversal to sunspot minimum, a phase of polar wind activity of the beginning cycle is superimposed on the weak contribution of shock events of the ending cycle; secondly, an equatorial phase mostly of shock events is superimposed on a variable contribution of short lived and sporadic stable equatorial stream activities; and thirdly a phase of low latitude shock events is superimposed on the polar stream interval of the following cycle. (orig.)

Vector magnetic fields in sunspots. I - Stokes profile analysis using the Marshall Space Flight Center magnetograph

Science.gov (United States)

Balasubramaniam, K. S.; West, E. A.

1991-01-01

The Marshall Space Flight Center (MSFC) vector magnetograph is a tunable filter magnetograph with a bandpass of 125 mA. Results are presented of the inversion of Stokes polarization profiles observed with the MSFC vector magnetograph centered on a sunspot to recover the vector magnetic field parameters and thermodynamic parameters of the spectral line forming region using the Fe I 5250.2 A spectral line using a nonlinear least-squares fitting technique. As a preliminary investigation, it is also shown that the recovered thermodynamic parameters could be better understood if the fitted parameters like Doppler width, opacity ratio, and damping constant were broken down into more basic quantities like temperature, microturbulent velocity, or density parameter.

Observational Evidence of Shallow Origins for the Magnetic Fields of Solar Cycles

Directory of Open Access Journals (Sweden)

Sara F. Martin

2018-05-01

Full Text Available Observational evidence for the origin of active region magnetic fields has been sought from published information on extended solar cycles, statistical distributions of active regions and ephemeral regions, helioseismology results, positional relationships to supergranules, and fine-scale magnetic structure of active regions and their sunspots during their growth. Statistical distributions of areas of ephemeral and active regions blend together to reveal a single power law. The shape of the size distribution in latitude of all active regions is independent of time during the solar cycle, yielding further evidence that active regions of all sizes belong to the same population. Elementary bipoles, identified also by other names, appear to be the building blocks of active regions; sunspots form from elementary bipoles and are therefore deduced to develop from the photosphere downward, consistent with helioseismic detection of downflows to 3–4 Mm below sunspots as well as long-observed downflows from chromospheric/coronal arch filaments into sunspots from their earliest appearance. Time-distance helioseismology has been effective in revealing flows related to sunspots to depths of 20 Mm. Ring diagram analysis shows a statistically significant preference for upflows to precede major active region emergence and downflows after flux emergence but both are often observed together or not detected. From deep-focus helioseismic techniques for seeking magnetic flux below the photosphere prior major active regions, there is evidence of acoustic travel-time perturbation signatures rising in the limited range of depths of 42–75 Mm but these have not been verified or found at more shallow depths by helioseismic holographic techniques. The development of active regions from clusters of elementary bipoles appears to be the same irrespective of how much flux an active region eventually develops. This property would be consistent with the magnetic fields of

Latitude and Power Characteristics of Solar Activity at the End of the Maunder Minimum

Science.gov (United States)

Ivanov, V. G.; Miletsky, E. V.

2017-12-01

Two important sources of information about sunspots in the Maunder minimum are the Spörer catalog (Spörer, 1889) and observations of the Paris observatory (Ribes and Nesme-Ribes, 1993), which cover in total the last quarter of the 17th and the first two decades of the 18th century. These data, in particular, contain information about sunspot latitudes. As we showed in (Ivanov et al., 2011; Ivanov and Miletsky, 2016), dispersions of sunspot latitude distributions are tightly related to sunspot indices, and we can estimate the level of solar activity in the past using a method which is not based on direct calculation of sunspots and weakly affected by loss of observational data. The latitude distributions of sunspots in the time of transition from the Maunder minimum to the regular regime of solar activity proved to be wide enough. It gives evidences in favor of, first, not very low cycle no.-3 (1712-1723) with the Wolf number in maximum W = 100 ± 50, and, second, nonzero activity in the maximum of cycle no.-4 (1700-1711) W = 60 ± 45. Therefore, the latitude distributions in the end of the Maunder minimum are in better agreement with the traditional Wolf numbers and new revisited indices of activity SN and GN (Clette et al., 2014; Svalgaard and Schatten, 2016) than with the GSN (Hoyt and Schatten, 1998); the latter provide much lower level of activity in this epoch.

Preliminary results from the orbiting solar observatory 8: Transition-zone dynamics over a sunspot

International Nuclear Information System (INIS)

Bruner, E.C. Jr.; Chipman, E.G.; Lites, B.W.; Rottman, G.J.; Shine, R.A.; Athay, R.G.; White, O.R.

1976-01-01

The University of Colorado experiment aboard OSO-8 observed the C IV 1548 A line in the bright plume over a sunspot. Transient redshifts at 5 minute intervals were studied, but the expected phenomena associated with simple Alfven wave effects were not observed

LIGHT BRIDGE IN A DEVELOPING ACTIVE REGION. II. NUMERICAL SIMULATION OF FLUX EMERGENCE AND LIGHT BRIDGE FORMATION

International Nuclear Information System (INIS)

Toriumi, Shin; Katsukawa, Yukio; Cheung, Mark C. M.

2015-01-01

Light bridges, the bright structure dividing umbrae in sunspot regions, show various activity events. In Paper I, we reported on an analysis of multi-wavelength observations of a light bridge in a developing active region (AR) and concluded that the activity events are caused by magnetic reconnection driven by magnetconvective evolution. The aim of this second paper is to investigate the detailed magnetic and velocity structures and the formation mechanism of light bridges. For this purpose, we analyze numerical simulation data from a radiative magnetohydrodynamics model of an emerging AR. We find that a weakly magnetized plasma upflow in the near-surface layers of the convection zone is entrained between the emerging magnetic bundles that appear as pores at the solar surface. This convective upflow continuously transports horizontal fields to the surface layer and creates a light bridge structure. Due to the magnetic shear between the horizontal fields of the bridge and the vertical fields of the ambient pores, an elongated cusp-shaped current layer is formed above the bridge, which may be favorable for magnetic reconnection. The striking correspondence between the observational results of Paper I and the numerical results of this paper provides a consistent physical picture of light bridges. The dynamic activity phenomena occur as a natural result of the bridge formation and its convective nature, which has much in common with those of umbral dots and penumbral filaments

Applying the Weighted Horizontal Magnetic Gradient Method to a Simulated Flaring Active Region

Science.gov (United States)

Korsós, M. B.; Chatterjee, P.; Erdélyi, R.

2018-04-01

Here, we test the weighted horizontal magnetic gradient (WG M ) as a flare precursor, introduced by Korsós et al., by applying it to a magnetohydrodynamic (MHD) simulation of solar-like flares. The preflare evolution of the WG M and the behavior of the distance parameter between the area-weighted barycenters of opposite-polarity sunspots at various heights is investigated in the simulated δ-type sunspot. Four flares emanated from this sunspot. We found the optimum heights above the photosphere where the flare precursors of the WG M method are identifiable prior to each flare. These optimum heights agree reasonably well with the heights of the occurrence of flares identified from the analysis of their thermal and ohmic heating signatures in the simulation. We also estimated the expected time of the flare onsets from the duration of the approaching–receding motion of the barycenters of opposite polarities before each single flare. The estimated onset time and the actual time of occurrence of each flare are in good agreement at the corresponding optimum heights. This numerical experiment further supports the use of flare precursors based on the WG M method.

June-July 1974 proton-flare region. III

International Nuclear Information System (INIS)

Bumba, V.

1982-01-01

In this third part of a series of papers describing the regularities in the magnetic field as well as solar activity development in a large portion of the solar atmosphere in which the processes related to the June-July 1974 proton-flare region formation take place, we study some characteristics of the solar wind which emanates from this portion of the solar atmosphere. It is shown that during the time when fast disintegration and disappearance of the large-scale characteristic magnetic field patterns occur and a sudden cease of sunspot, flare and coronal activity is observed, daily geomagnetic character figures C9 reach their maximum. This solar wind enhancement is taken as one of the last observable manifestations of the whole complex process. (author)

WAVES AS THE SOURCE OF APPARENT TWISTING MOTIONS IN SUNSPOT PENUMBRAE

International Nuclear Information System (INIS)

Bharti, L.; Cameron, R. H.; Hirzberger, J.; Solanki, S. K.; Rempel, M.

2012-01-01

The motion of dark striations across bright filaments in a sunspot penumbra has become an important new diagnostic of convective gas flows in penumbral filaments. The nature of these striations has, however, remained unclear. Here, we present an analysis of small-scale motions in penumbral filaments in both simulations and observations. The simulations, when viewed from above, show fine structure with dark lanes running outward from the dark core of the penumbral filaments. The dark lanes either occur preferentially on one side or alternate between both sides of the filament. We identify this fine structure with transverse (kink) oscillations of the filament, corresponding to a sideways swaying of the filament. These oscillations have periods in the range of 5-7 minutes and propagate outward and downward along the filament. Similar features are found in observed G-band intensity time series of penumbral filaments in a sunspot located near disk center obtained by the Broadband Filter Imager on board the Hinode. We also find that some filaments show dark striations moving to both sides of the filaments. Based on the agreement between simulations and observations we conclude that the motions of these striations are caused by transverse oscillations of the underlying bright filaments.

Influence of the sunspot cycle on the Northern Hemisphere wintertime circulation from long upper-air data sets

Directory of Open Access Journals (Sweden)

Y. Brugnara

2013-07-01

Full Text Available Here we present a study of the 11 yr sunspot cycle's imprint on the Northern Hemisphere atmospheric circulation, using three recently developed gridded upper-air data sets that extend back to the early twentieth century. We find a robust response of the tropospheric late-wintertime circulation to the sunspot cycle, independent from the data set. This response is particularly significant over Europe, although results show that it is not directly related to a North Atlantic Oscillation (NAO modulation; instead, it reveals a significant connection to the more meridional Eurasian pattern (EU. The magnitude of mean seasonal temperature changes over the European land areas locally exceeds 1 K in the lower troposphere over a sunspot cycle. We also analyse surface data to address the question whether the solar signal over Europe is temporally stable for a longer 250 yr period. The results increase our confidence in the existence of an influence of the 11 yr cycle on the European climate, but the signal is much weaker in the first half of the period compared to the second half. The last solar minimum (2005 to 2010, which was not included in our analysis, shows anomalies that are consistent with our statistical results for earlier solar minima.

On the statistical aspects of sunspot number time series and its association with the summer-monsoon rainfall over India

Science.gov (United States)

Chattopadhyay, Surajit; Chattopadhyay, Goutami

The present paper reports studies on the association between the mean annual sunspot numbers and the summer monsoon rainfall over India. The cross correlations have been studied. After Box-Cox transformation, the time spectral analysis has been executed and it has been found that both of the time series have an important spectrum at the fifth harmonic. An artificial neural network (ANN) model has been developed on the data series averaged continuously by five years and the neural network could establish a predictor-predict and relationship between the sunspot numbers and the mean yearly summer monsoon rainfall over India.

Possibilities for Estimating Horizontal Electrical Currents in Active Regions on the Sun

Science.gov (United States)

Fursyak, Yu. A.; Abramenko, V. I.

2017-12-01

Part of the "free" magnetic energy associated with electrical current systems in the active region (AR) is released during solar flares. This proposition is widely accepted and it has stimulated interest in detecting electrical currents in active regions. The vertical component of an electric current in the photosphere can be found by observing the transverse magnetic field. At present, however, there are no direct methods for calculating transverse electric currents based on these observations. These calculations require information on the field vector measured simultaneously at several levels in the photosphere, which has not yet been done with solar instrumentation. In this paper we examine an approach to calculating the structure of the square of the density of a transverse electrical current based on a magnetogram of the vertical component of the magnetic field in the AR. Data obtained with the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamic Observatory (SDO) for the AR of NOAA AR 11283 are used. It is shown that (1) the observed variations in the magnetic field of a sunspot and the proposed estimate of the density of an annular horizontal current around the spot are consistent with Faraday's law and (2) the resulting estimates of the magnitude of the square of the density of the horizontal current {j}_{\\perp}^2 = (0.002- 0.004) A2/m4 are consistent with previously obtained values of the density of a vertical current in the photosphere. Thus, the proposed estimate is physically significant and this method can be used to estimate the density and structure of transverse electrical currents in the photosphere.

Transition-Region/Coronal Signatures of Penumbral Microjets: Hi-C, SDO/AIA and Hinode (SOT/FG) Observations

Science.gov (United States)

Tiwari, Sanjiv K.; Alpert, Shane E.; Moore, Ronald L.; Winebarger, Amy R.

2014-01-01

Penumbral microjets are bright, transient features seen in the chromosphere of sunspot penumbrae. Katsuaka et al. (2007) noted their ubiquity and characterized them using the Ca II H-line filter on Hinode's Solar Optical Telescope (SOT). The jets are 1000{4000 km in length, 300{400 km in width, and last less than one minute. It was proposed that these penumbral microjets could contribute to the transition-region and coronal heating above sunspots. We examine whether these microjets appear in the transition-region (TR) and/or corona or are related{ temporally and spatially{ to similar brightenings in the TR and/or corona. First, we identify penumbral microjets with the SOT's Ca II H-line filter. The chosen sunspot is observed on July 11, 2012 from 18:50:00 UT to 20:00:00 UT at approx. 14 inches, -30 inches. We then examine the sunspot in the same field of view and at the same time in other wavelengths. We use the High Resolution Coronal Imager Telescope (Hi-C) at 193A and the 1600A, 304A, 171A, 193A, and 94A passbands of the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamic Observatory. We include examples of these jets and where they should appear in the other passbands, but find no signifcant association, except for a few jets with longer lifetimes and bigger sizes seen at locations in the penumbra with repeated stronger brightenings. We conclude that the normal microjets are not heated to transition-region/coronal temperatures, but the larger jets are.

SPATIAL DISTRIBUTIONS OF ABSORPTION, LOCAL SUPPRESSION, AND EMISSIVITY REDUCTION OF SOLAR ACOUSTIC WAVES IN MAGNETIC REGIONS

International Nuclear Information System (INIS)

Chou, D.-Y.; Yang, M.-H.; Zhao Hui; Liang Zhichao; Sun, M.-T.

2009-01-01

Observed acoustic power in magnetic regions is lower than the quiet Sun because of absorption, emissivity reduction, and local suppression of solar acoustic waves in magnetic regions. In the previous studies, we have developed a method to measure the coefficients of absorption, emissivity reduction, and local suppression of sunspots. In this study, we go one step further to measure the spatial distributions of three coefficients in two active regions, NOAA 9055 and 9057. The maps of absorption, emissivity reduction, and local suppression coefficients correlate with the magnetic map, including plage regions, except the emissivity reduction coefficient of NOAA 9055 where the emissivity reduction coefficient is too weak and lost among the noise.

Fully Automated Sunspot Detection and Classification Using SDO HMI Imagery in MATLAB

Science.gov (United States)

2014-03-27

initiating the java program scripted to communicate with the SOON telescope used for continual observation of the sun. The SOON telescope is used at...proximity of spots refers to the angular separation between different spots that could make up a group. The area of each sunspot means the total area...degrees and the different magnetic polarities of each spot being considered. For a spot pair that has the same polarity and small angular separation

Preliminary observations and results obtained with the ultraviolet spectrometer and polarimeter. [for Solar Maximum Mission

Science.gov (United States)

Tandberg-Hassen, E.; Cheng, C. C.; Athay, R. G.; Beckers, J. M.; Brandt, J. C.; Chapman, R. D.; Bruner, E. C.; Henze, W.; Hyder, C. L.; Gurman, J. B.

1981-01-01

New observation with the Ultraviolet Spectrometer and Polarimeter (UVSP) of a number of manifestations of solar activity obtained during the first three months of Solar Maximum Mission operations are presented. Attention is given to polarimetry in sunspots, oscillations above sunspots, density diagnostics of transition-zone plasmas in active regions, and the eruptive prominence - coronal transient link.

Observations of the birth and fine structure of sunspot penumbrae

International Nuclear Information System (INIS)

Collados, M.; Garcia de la Rosa, J.I.; Moreno-Insertis, F.; Vazquez, M.

1985-01-01

High resolution white-light pictures of sunspot penumbrae are presented. These include pictures showing details of their filamentary structure and some instances of birth of a penumbra. The observations are discussed in the framework of current penumbra theories. A series of pictures have been presented, which give additional evidence of the existence of dark penumbral filaments as individual structures. With respect to the birth of the penumbra some new observational aspects can be seen. The existence of the filamentary penumbra even in the first moments, its non uniformity and its short length are the major aspects derived from the pictures

CORONAL DYNAMIC ACTIVITIES IN THE DECLINING PHASE OF A SOLAR CYCLE

Energy Technology Data Exchange (ETDEWEB)

Jang, Minhwan; Choe, G. S. [Department of Astronomy and Space Science, Kyung Hee University, Yongin 17104 (Korea, Republic of); Woods, T. N. [Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303 (United States); Hong, Sunhak, E-mail: gchoe@khu.ac.kr [School of Space Research, Kyung Hee University, Yongin 17104 (Korea, Republic of)

2016-12-10

It has been known that some solar activity indicators show a double-peak feature in their evolution through a solar cycle, which is not conspicuous in sunspot number. In this Letter, we investigate the high solar dynamic activity in the declining phase of the sunspot cycle by examining the evolution of polar and low-latitude coronal hole (CH) areas, splitting and merging events of CHs, and coronal mass ejections (CMEs) detected by SOHO /LASCO C3 in solar cycle 23. Although the total CH area is at its maximum near the sunspot minimum, in which polar CHs prevail, it shows a comparable second maximum in the declining phase of the cycle, in which low-latitude CHs are dominant. The events of CH splitting or merging, which are attributed to surface motions of magnetic fluxes, are also mostly populated in the declining phase of the cycle. The far-reaching C3 CMEs are also overpopulated in the declining phase of the cycle. From these results we suggest that solar dynamic activities due to the horizontal surface motions of magnetic fluxes extend far in the declining phase of the sunspot cycle.

CORONAL DYNAMIC ACTIVITIES IN THE DECLINING PHASE OF A SOLAR CYCLE

International Nuclear Information System (INIS)

Jang, Minhwan; Choe, G. S.; Woods, T. N.; Hong, Sunhak

2016-01-01

It has been known that some solar activity indicators show a double-peak feature in their evolution through a solar cycle, which is not conspicuous in sunspot number. In this Letter, we investigate the high solar dynamic activity in the declining phase of the sunspot cycle by examining the evolution of polar and low-latitude coronal hole (CH) areas, splitting and merging events of CHs, and coronal mass ejections (CMEs) detected by SOHO /LASCO C3 in solar cycle 23. Although the total CH area is at its maximum near the sunspot minimum, in which polar CHs prevail, it shows a comparable second maximum in the declining phase of the cycle, in which low-latitude CHs are dominant. The events of CH splitting or merging, which are attributed to surface motions of magnetic fluxes, are also mostly populated in the declining phase of the cycle. The far-reaching C3 CMEs are also overpopulated in the declining phase of the cycle. From these results we suggest that solar dynamic activities due to the horizontal surface motions of magnetic fluxes extend far in the declining phase of the sunspot cycle.

Resonance of about-weekly human heart rate rhythm with solar activity change.

Science.gov (United States)

Cornelissen, G; Halberg, F; Wendt, H W; Bingham, C; Sothern, R B; Haus, E; Kleitman, E; Kleitman, N; Revilla, M A; Revilla, M; Breus, T K; Pimenov, K; Grigoriev, A E; Mitish, M D; Yatsyk, G V; Syutkina, E V

1996-12-01

In several human adults, certain solar activity rhythms may influence an about 7-day rhythm in heart rate. When no about-weekly feature was found in the rate of change in sunspot area, a measure of solar activity, the double amplitude of a circadian heart rate rhythm, approximated by the fit of a 7-day cosine curve, was lower, as was heart rate corresponds to about-weekly features in solar activity and/or relates to a sunspot cycle.

Sunspots and the physics of magnetic flux tubes in the sun

International Nuclear Information System (INIS)

Ballegooijen, A.A. van.

1982-01-01

This thesis refers to the sub-surface structure of the solar magnetic field. Following an introductory chapter, chapter II presents an analysis of spectroscopic observations of a sunspot at infrared wavelengths and models of the temperature stratification in the sunspot atmosphere are derived. The main subject of this thesis concerns the structure of the magnetic field deep down below the stellar surface, near the base of the convective envelope. In Chapter III the stability of toroidal flux tubes to wave-like perturbations is discussed, assuming that the tubes are neutrally buoyant. A model is proposed in which the toroidal flux tubes are neutrally buoyant and located in a stably stratified layer just below the base of the convective zone. On the basis of some simple assumptions for the temperature stratification in this storage layer the author considers in Chapter IV the properties of the vertical flux tubes in the convective zone. The adiabatic flux model cannot satisfactorily be applied to the simplified model of the storage layer, so that the problem of magnetic flux storage is reconsidered in Chapter V. A new model of the temperature stratification at the interface of convective zone and radiative interior of the sun is described. Finally, in Chapter VI, the stability of toroidal flux tubes in a differentially rotating star are discussed. It is demonstrated that for realistic values of the magnetic field strength, rotation has a strong effect on the stability of the toroidal flux tubes. (C.F.)

Sunspots and the physics of magnetic flux tubes. II. Aerodynamic drag

International Nuclear Information System (INIS)

Parker, E.N.

1979-01-01

The aerodynamic drag on a slender flux tube stretched vertically across a convective cell may push the flux tube into the updrafts or into the downdrafts, depending on the density stratification of the convecting fluid and the asymmetry of the fluid motions. The drag is approximately proportional to the local kinetic energy density, so the density stratification weights the drag in favor of the upper layers where the density is low, tending to push the vertical tube into the downdrafts. If, however, the horizontal motions in the convective cell are concentrated toward the bottom of the cell, they may dominate over the upper layers, pushing the tube into the updrafts. In the simple, idealized circumstance of a vertical tube extending across a fluid of uniform density in a convective cell that is symmetric about its midplane, the net aerodynamic drag vanishes in lowest order. The higher order contributions, including the deflection of the tube, then provide a nonvanishing force pushing the tube into a stable equilibrium midway between the updraft and the downdraft.It is pointed out that in the strongly stratified convective zone of the Sun, a downdraft herds flux tubes together into a cluster, while an updraft disperses them. To account for the observed strong cohesion of the cluster of flux tubes that make up a sunspot, we propose a downdraft of the order 2 km s - 1 through the cluster of seprate tubes beneath the sunspot

ENHANCEMENT OF A SUNSPOT LIGHT WALL WITH EXTERNAL DISTURBANCES

Energy Technology Data Exchange (ETDEWEB)

Yang, Shuhong; Zhang, Jun [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Erdélyi, Robert, E-mail: shuhongyang@nao.cas.cn [Solar Physics and Space Plasma Research Centre, School of Mathematics and Statistics, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom)

2016-12-20

Based on the Interface Region Imaging Spectrograph observations, we study the response of a solar sunspot light wall to external disturbances. A flare occurrence near the light wall caused material to erupt from the lower solar atmosphere into the corona. Some material falls back to the solar surface and hits the light bridge (i.e., the base of the light wall), then sudden brightenings appear at the wall base followed by the rise of wall top, leading to an increase of the wall height. Once the brightness of the wall base fades, the height of the light wall begins to decrease. Five hours later, another nearby flare takes place, and a bright channel is formed that extends from the flare toward the light bridge. Although no obvious material flow along the bright channel is found, some ejected material is conjectured to reach the light bridge. Subsequently, the wall base brightens and the wall height begins to increase again. Once more, when the brightness of the wall base decays, the wall top fluctuates to lower heights. We suggest, based on the observed cases, that the interaction of falling material and ejected flare material with the light wall results in the brightenings of wall base and causes the height of the light wall to increase. Our results reveal that the light wall can be not only powered by the linkage of p -mode from below the photosphere, but may also be enhanced by external disturbances, such as falling material.

Formation of a double-decker magnetic flux rope in the sigmoidal solar active region 11520

Energy Technology Data Exchange (ETDEWEB)

Cheng, X.; Ding, M. D.; Zhang, J.; Guo, Y. [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Sun, X. D. [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305 (United States); Wang, Y. M. [School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026 (China); Kliem, B. [Institute of Physics and Astronomy, University of Potsdam, D-14476 Potsdam (Germany); Deng, Y. Y., E-mail: xincheng@nju.edu.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

2014-07-10

In this paper, we address the formation of a magnetic flux rope (MFR) that erupted on 2012 July 12 and caused a strong geomagnetic storm event on July 15. Through analyzing the long-term evolution of the associated active region observed by the Atmospheric Imaging Assembly and the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory, it is found that the twisted field of an MFR, indicated by a continuous S-shaped sigmoid, is built up from two groups of sheared arcades near the main polarity inversion line a half day before the eruption. The temperature within the twisted field and sheared arcades is higher than that of the ambient volume, suggesting that magnetic reconnection most likely works there. The driver behind the reconnection is attributed to shearing and converging motions at magnetic footpoints with velocities in the range of 0.1-0.6 km s{sup –1}. The rotation of the preceding sunspot also contributes to the MFR buildup. Extrapolated three-dimensional non-linear force-free field structures further reveal the locations of the reconnection to be in a bald-patch region and in a hyperbolic flux tube. About 2 hr before the eruption, indications of a second MFR in the form of an S-shaped hot channel are seen. It lies above the original MFR that continuously exists and includes a filament. The whole structure thus makes up a stable double-decker MFR system for hours prior to the eruption. Eventually, after entering the domain of instability, the high-lying MFR impulsively erupts to generate a fast coronal mass ejection and X-class flare; while the low-lying MFR remains behind and continuously maintains the sigmoidicity of the active region.

Formation of a double-decker magnetic flux rope in the sigmoidal solar active region 11520

International Nuclear Information System (INIS)

Cheng, X.; Ding, M. D.; Zhang, J.; Guo, Y.; Sun, X. D.; Wang, Y. M.; Kliem, B.; Deng, Y. Y.

2014-01-01

In this paper, we address the formation of a magnetic flux rope (MFR) that erupted on 2012 July 12 and caused a strong geomagnetic storm event on July 15. Through analyzing the long-term evolution of the associated active region observed by the Atmospheric Imaging Assembly and the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory, it is found that the twisted field of an MFR, indicated by a continuous S-shaped sigmoid, is built up from two groups of sheared arcades near the main polarity inversion line a half day before the eruption. The temperature within the twisted field and sheared arcades is higher than that of the ambient volume, suggesting that magnetic reconnection most likely works there. The driver behind the reconnection is attributed to shearing and converging motions at magnetic footpoints with velocities in the range of 0.1-0.6 km s –1 . The rotation of the preceding sunspot also contributes to the MFR buildup. Extrapolated three-dimensional non-linear force-free field structures further reveal the locations of the reconnection to be in a bald-patch region and in a hyperbolic flux tube. About 2 hr before the eruption, indications of a second MFR in the form of an S-shaped hot channel are seen. It lies above the original MFR that continuously exists and includes a filament. The whole structure thus makes up a stable double-decker MFR system for hours prior to the eruption. Eventually, after entering the domain of instability, the high-lying MFR impulsively erupts to generate a fast coronal mass ejection and X-class flare; while the low-lying MFR remains behind and continuously maintains the sigmoidicity of the active region.

The topside ionosphere above Arecibo at equinox during sunspot maximum

International Nuclear Information System (INIS)

Bailey, G.J.

1980-01-01

The coupled time-dependent 0 + and H + continuity and momentum equations and 0 + , H + and electron heat balance equations are solved simultaneously within the L = 1.4 (Arecibo) magnetic flux tube between an altitude of 120 km and the equatorial plane. The results of the calculations are used in a study of the topside ionosphere above Arecibo at equinox during sunspot maximum. Magnetically quiet conditions are assumed. The results of the calculations show that the L = 1.4 magnetic flux tube becomes saturated from an arbitrary state within 2-3 days. During the day the ion content of the magnetic flux tube consists mainly of 0 + whereas 0 + and H + are both important during the night. There is an altitude region in the topside ionosphere during the day where ion-counterstreaming occurs with H + flowing downward and 0 + flowing upward. The conditions causing this ion-counterstreaming are discussed. There is a net chemical gain of H + at the higher altitudes. This H + diffuses both upwards and downwards whilst 0 + diffuses upwards from its solar e.u.v. production source which is most important at the lower altitudes. During the night the calculated 0 + and H + temperatures are very nearly equal whereas during the day there are occasions when the H + temperature exceeds the 0 - temperature by about 300 K. (author)

NUMERICAL SIMULATIONS OF CONVERSION TO ALFVÉN WAVES IN SUNSPOTS

International Nuclear Information System (INIS)

Khomenko, E.; Cally, P. S.

2012-01-01

We study the conversion of fast magnetoacoustic waves to Alfvén waves by means of 2.5D numerical simulations in a sunspot-like magnetic configuration. A fast, essentially acoustic, wave of a given frequency and wave number is generated below the surface and propagates upward through the Alfvén/acoustic equipartition layer where it splits into upgoing slow (acoustic) and fast (magnetic) waves. The fast wave quickly reflects off the steep Alfvén speed gradient, but around and above this reflection height it partially converts to Alfvén waves, depending on the local relative inclinations of the background magnetic field and the wavevector. To measure the efficiency of this conversion to Alfvén waves we calculate acoustic and magnetic energy fluxes. The particular amplitude and phase relations between the magnetic field and velocity oscillations help us to demonstrate that the waves produced are indeed Alfvén waves. We find that the conversion to Alfvén waves is particularly important for strongly inclined fields like those existing in sunspot penumbrae. Equally important is the magnetic field orientation with respect to the vertical plane of wave propagation, which we refer to as 'field azimuth'. For a field azimuth less than 90° the generated Alfvén waves continue upward, but above 90° downgoing Alfvén waves are preferentially produced. This yields negative Alfvén energy flux for azimuths between 90° and 180°. Alfvén energy fluxes may be comparable to or exceed acoustic fluxes, depending upon geometry, though computational exigencies limit their magnitude in our simulations.

A dynamo theory prediction for solar cycle 22: Sunspot number, radio flux, exospheric temperature, and total density at 400 km

Science.gov (United States)

Schatten, K. H.; Hedin, A. E.

1986-01-01

Using the dynamo theory method to predict solar activity, a value for the smoothed sunspot number of 109 + or - 20 is obtained for solar cycle 22. The predicted cycle is expected to peak near December, 1990 + or - 1 year. Concommitantly, F(10.7) radio flux is expected to reach a smoothed value of 158 + or - 18 flux units. Global mean exospheric temperature is expected to reach 1060 + or - 50 K and global total average total thermospheric density at 400 km is expected to reach 4.3 x 10 to the -15th gm/cu cm + or - 25 percent.

A dynamo theory prediction for solar cycle 22 - Sunspot number, radio flux, exospheric temperature, and total density at 400 km

Science.gov (United States)

Schatten, K. H.; Hedin, A. E.

1984-01-01

Using the 'dynamo theory' method to predict solar activity, a value for the smoothed sunspot number of 109 + or - 20 is obtained for solar cycle 22. The predicted cycle is expected to peak near December, 1990 + or - 1 year. Concommitantly, F(10.7) radio flux is expected to reach a smoothed value of 158 + or - 18 flux units. Global mean exospheric temperature is expected to reach 1060 + or - 50 K and global total average total thermospheric density at 400 km is expected to reach 4.3 x 10 to the -15th gm/cu cm + or - 25 percent.

Study of spatial and temporal characteristics of L-band scintillations over the Indian low-latitude region and their possible effects on GPS navigation

Directory of Open Access Journals (Sweden)

P. V. S. Rama Rao

2006-07-01

Full Text Available The scintillation data (S4-index at the L-band frequency of 1.575GHz, recorded from a total of 18 GPS receivers installed at different locations in India under the GAGAN project, have provided us with a unique opportunity, for the first time in the Indian region, to make a simultaneous study of spatio-temporal and intensity characteristics of the trans-ionospheric scintillations during the 18-month, low sunspot activity (LSSA period from January 2004 to July 2005. During this period, the occurrence of scintillations is found to be maximum around the pre-midnight hours of equinox months, with very little activity during the post-midnight hours. No significant scintillation activity is observed during the summer and winter months of the period of observation. The intensity (S4 index of the scintillation activity is stronger around the equatorial ionization anomaly (EIA region in the geographic latitude range of 15° to 25° N in the Indian region. These scintillations are often accompanied by the TEC depletions with durations ranging from 5 to 25 min and magnitudes from 5 to 15 TEC units which affect the positional accuracy of the GPS by 1 to 3 m. Further, during the intense scintillation events (S4>0.45≈10 dB, the GPS receiver is found to lose its lock for a short duration of 1 to 4 min, increasing the error bounds effecting the integrity of the SBAS operation. During the present period of study, a total of 395 loss of lock events are observed in the Indian EIA region; this number is likely to increase during the high sunspot activity (HSSA period, creating more adverse conditions for the trans-ionospheric communications and the GPS-based navigation systems.

The solar activity cycle physical causes and consequences

CERN Document Server

Hudson, Hugh; Petrovay, Kristóf; Steiger, Rudolf

2015-01-01

A collection of papers edited by four experts in the field, this book sets out to describe the way solar activity is manifested in observations of the solar interior, the photosphere, the chromosphere, the corona and the heliosphere. The 11-year solar activity cycle, more generally known as the sunspot cycle, is a fundamental property of the Sun.  This phenomenon is the generation and evolution of magnetic fields in the Sun’s convection zone, the photosphere.  It is only by the careful enumeration and description of the phenomena and their variations that one can clarify their interdependences.   The sunspot cycle has been tracked back about four centuries, and it has been recognized that to make this data set a really useful tool in understanding how the activity cycle works and how it can be predicted, a very careful and detailed effort is needed to generate sunspot numbers.  This book deals with this topic, together with several others that present related phenomena that all indicate the physical pr...

Values of Kp Indices, Ap Indices, Cp Indices, C9 Indices, Sunspot Number, and 10.7 cm Flux

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This data file consists of Kp indices, Ap indices, Cp indices, C9 indices, sunspot number, and 10.7 cm flux. The most often requested parameter of this file are the...

Fan-shaped jets above the light bridge of a sunspot driven by reconnection

Science.gov (United States)

Robustini, Carolina; Leenaarts, Jorrit; de la Cruz Rodriguez, Jaime; Rouppe van der Voort, Luc

2016-05-01

We report on a fan-shaped set of high-speed jets above a strongly magnetized light bridge (LB) of a sunspot observed in the Hα line. We study the origin, dynamics, and thermal properties of the jets using high-resolution imaging spectroscopy in Hα from the Swedish 1m Solar Telescope and data from the Solar Dynamics Observatory and Hinode. The Hα jets have lengths of 7-38 Mm, are impulsively accelerated to a speed of ~100 km s-1 close to photospheric footpoints in the LB, and exhibit a constant deceleration consistent with solar effective gravity. They are predominantly launched from one edge of the light bridge, and their footpoints appear bright in the Hα wings. Atmospheric Imaging Assembly data indicates elongated brightenings that are nearly co-spatial with the Hα jets. We interpret them as jets of transition region temperatures. The magnetic field in the light bridge has a strength of 0.8-2 kG and it is nearly horizontal. All jet properties are consistent with magnetic reconnection as the driver. Movies associated to Figs. 1 and 2 are available in electronic form at http://www.aanda.org

Determination of the Alfvén Speed and Plasma-beta Using the Seismology of Sunspot Umbra

Energy Technology Data Exchange (ETDEWEB)

Cho, I.-H.; Moon, Y.-J.; Nakariakov, V. M.; Park, J.; Choi, S. [Department of Astronomy and Space Science, Kyung Hee University, Yongin 446-701 (Korea, Republic of); Cho, K.-S.; Bong, S.-C.; Baek, J.-H.; Kim, Y.-H.; Lee, J., E-mail: ihjo@khu.ac.kr [Space Science Division, Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of)

2017-03-01

For 478 centrally located sunspots observed in the optical continuum with Solar Dynamics Observatory /Helioseismic Magnetic Imager, we perform seismological diagnostics of the physical parameters of umbral photospheres. The new technique is based on the theory of slow magnetoacoustic waves in a non-isothermally stratified photosphere with a uniform vertical magnetic field. We construct a map of the weighted frequency of three-minute oscillations inside the umbra and use it for the estimation of the Alfvén speed, plasma-beta, and mass density within the umbra. We find the umbral mean Alfvén speed ranges between 10.5 and 7.5 km s{sup −1} and is negatively correlated with magnetic field strength. The umbral mean plasma-beta is found to range approximately between 0.65 and 1.15 and does not vary significantly from pores to mature sunspots. The mean density ranges between (1–6) × 10{sup −4} kg m{sup −3} and shows a strong positive correlation with magnetic field strength.

Active region structures in the transition region and corona

International Nuclear Information System (INIS)

Webb, D.F.

1981-01-01

Observational aspects of the transition region and coronal structures of the solar active region are reviewed with an emphasis on imaging of the plasma loops which act as tracers of the magnetic flux loops. The study of the basic structure of an active region is discussed in terms of the morphological and thermal classifications of active region loops, including umbral structures, and observational knowledge of the thermal structure of loops is considered in relation to scaling laws, emission measures and the structures of individual loops. The temporal evolution of active region loop structures is reviewed with emphasis on ephemeral regions and the emergence of active regions. Planned future spaceborne observations of active region loop structures in the EUV and soft X-ray regions are also indicated

Chromospheric Inversions of a Micro-flaring Region

Energy Technology Data Exchange (ETDEWEB)

Reid, A.; Henriques, V.; Mathioudakis, M. [Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, BT7 1NN, Northern Ireland (United Kingdom); Doyle, J. G. [Armagh Observatory and Planetarium, College Hill, Armagh, BT61 9DG (United Kingdom); Ray, T., E-mail: aaron.reid@qub.ac.uk [Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2 (Ireland)

2017-08-20

We use spectropolarimetric observations of the Ca ii 8542 Å line, taken from the Swedish 1 m Solar Telescope, in an attempt to recover dynamic activity in a micro-flaring region near a sunspot via inversions. These inversions show localized mean temperature enhancements of ∼1000 K in the chromosphere and upper photosphere, along with co-spatial bi-directional Doppler shifting of 5–10 km s{sup −1}. This heating also extends along a nearby chromospheric fibril, which is co-spatial to 10–15 km s{sup −1} downflows. Strong magnetic flux cancellation is also apparent in one of the footpoints, and is concentrated in the chromosphere. This event more closely resembles that of an Ellerman Bomb, though placed slightly higher in the atmosphere than what is typically observed.

Effects of Solar Activity and Space Environment in 2003 Oct.

Directory of Open Access Journals (Sweden)

Kyung-Seok Cho

2004-12-01

Full Text Available In this paper, we present a good example of extreme solar and geomagnetic activities from October to November, 2003. These activities are characterized by very large sunspot groups, X-class solar flares, strong particle events, and huge geomagnetic storms. We discuss ground-based and space-based data in terms of space weather scales. Especially, we present several solar and geomagnetic disturbance data produced in Korea : sunspots, geo-magnetograms, aurora, Ionogram, and Total Electron Content (TEC map by GPS data. Finally, we introduce some examples of the satellite orbit and communication effects caused by these activities; e.g., the disturbances of the KOMPSAT-1 operational orbit and HF communication.

THE MYSTERIOUS CASE OF THE SOLAR ARGON ABUNDANCE NEAR SUNSPOTS IN FLARES

International Nuclear Information System (INIS)

Doschek, G. A.; Warren, H. P.

2016-01-01

Recently we discussed an enhancement of the abundance of Ar xiv relative to Ca xiv near a sunspot during a flare, observed in spectra recorded by the Extreme-ultraviolet Imaging Spectrometer (EIS) on the Hinode spacecraft. The observed Ar xiv/Ca xiv ratio yields an argon/calcium abundance ratio seven times greater than expected from the photospheric abundance. Such a large abundance anomaly is unprecedented in the solar atmosphere. We interpreted this result as being due to an inverse first ionization potential (FIP) effect. In the published work, two lines of Ar xiv were observed, and one line was tentatively identified as an Ar xi line. In this paper, we report observing a similar enhancement in a full-CCD EIS flare spectrum in 13 argon lines that lie within the EIS wavelength ranges. The observed lines include two Ar xi lines, four Ar xiii lines, six Ar xiv lines, and one Ar xv line. The enhancement is far less than reported in Doschek et al. but exhibits similar morphology. The argon abundance is close to a photospheric abundance in the enhanced area, and the abundance could be photospheric. This enhancement occurs in association with a sunspot in a small area only a few arcseconds (1″ = about 700 km) in size. There is no enhancement effect observed in the normally high-FIP sulfur and oxygen line ratios relative to lines of low-FIP elements available to EIS. Calculations of path lengths in the strongest enhanced area in Doschek et al. indicate a depletion of low-FIP elements.

Remote sensing of auroral E region plasma structures by radio, radar, and UV techniques at solar minimum

International Nuclear Information System (INIS)

Basu, S.; Valladares, C.E.; Basu, S.; Eastes, R.; Huffman, R.E.; Daniell, R.E.; Chaturvedi, P.K.; Livingston, R.C.

1993-01-01

The unique capability of the Polar BEAR satellite to simultaneously image auroral luminosities at multiple ultraviolet (UV) wavelengths and to remote sense large-scale (hundreds to tens of kilometers) and small-scale (kilometers to hundreds of meters) plasma density structures with its multifrequency beacon package is utilized to probe the auroral E region in the vicinity of the incoherent scatter radar (ISR) facility near Sondrestrom. In particular, we present coordinated observations on two nights obtained during the sunspot minimum (sunspot number < 10) January-February 1987 period when good spatial and temporal conjunction was obtained between Polar BEAR overflights and Sondrestrom ISR measurements. With careful coordinated observations we were able to confirm that the energetic particle precipitation responsible for the UV emissions causes the electron density increases in the E region. The integrations up to the topside of these ISR electron density profiles were consistent with the total electron content (TEC) measured by the Polar BEAR satellite. An electron transport model was utilized to determine quantitatively the electron density profiles which could be produced by the particle precipitation, which also produced multiple UV emissions measured by the imager; these profiles were found to be in good agreement with the observed ISR profiles in the E region. This outer scale size is also consistent with the measured phase to amplitude scintillation ratio. An estimate of the linear growth rate of the gradient-drift instability in the E region shows that these plasma density irregularities could have been generated by this process. The mutual consistency of these different sets of measurements provides confidence in the ability of the different techniques to remote sense large- and small-scale plasma density structures in the E region at least during sunspot minimum when the convection-dominated high-latitude F region is fairly weak. 56 refs., 16 figs

MAXIMUM CORONAL MASS EJECTION SPEED AS AN INDICATOR OF SOLAR AND GEOMAGNETIC ACTIVITIES

International Nuclear Information System (INIS)

Kilcik, A.; Yurchyshyn, V. B.; Abramenko, V.; Goode, P. R.; Gopalswamy, N.; Ozguc, A.; Rozelot, J. P.

2011-01-01

We investigate the relationship between the monthly averaged maximal speeds of coronal mass ejections (CMEs), international sunspot number (ISSN), and the geomagnetic Dst and Ap indices covering the 1996-2008 time interval (solar cycle 23). Our new findings are as follows. (1) There is a noteworthy relationship between monthly averaged maximum CME speeds and sunspot numbers, Ap and Dst indices. Various peculiarities in the monthly Dst index are correlated better with the fine structures in the CME speed profile than that in the ISSN data. (2) Unlike the sunspot numbers, the CME speed index does not exhibit a double peak maximum. Instead, the CME speed profile peaks during the declining phase of solar cycle 23. Similar to the Ap index, both CME speed and the Dst indices lag behind the sunspot numbers by several months. (3) The CME number shows a double peak similar to that seen in the sunspot numbers. The CME occurrence rate remained very high even near the minimum of the solar cycle 23, when both the sunspot number and the CME average maximum speed were reaching their minimum values. (4) A well-defined peak of the Ap index between 2002 May and 2004 August was co-temporal with the excess of the mid-latitude coronal holes during solar cycle 23. The above findings suggest that the CME speed index may be a useful indicator of both solar and geomagnetic activities. It may have advantages over the sunspot numbers, because it better reflects the intensity of Earth-directed solar eruptions.

Sun in the Epoch ``LOWERED'' Solar Activity: the Comparative Analysis of the Current 24 Solar Cycle and Past Authentic Low Cycles

Science.gov (United States)

Vitaly, Ishkov

A reliable series of the relative numbers of sunspots (14 solar cycles ‒ 165 years) it leads to the only scenario of solar activity cycles - to the alternation of epochs of “increased” (18 ‒ 22 cycles of solar activity) and “lowered” (12 ‒ 16 and 24 ‒ ...) solar activity with the periods of solar magnetic field reconstruction in solar zone of the sunspots formation (11, 12, 23) from one epoch to another. The regime of the produce of magnetic field significantly changes in these periods, providing to the subsequent 5 cycles the stable conditions of solar activity. Space solar research made it possible to sufficiently fully investigate characteristics and parameters of the solar cycles for the epoch of “increased” (20 ‒ 22 cycles) solar activity and period of the reconstruction (22 ‒ 23 cycles) to the epoch of “lowered” solar activity (24 ‒ ... cycles). In this scenario 24 solar cycle is the first solar cycle of the second epoch of “lowered” solar activity. Therefore his development and characteristics roughly must be described in the context of the low solar cycles development (12, 14, and 16). In the current solar cycle the sunspot-forming activity is lowered, the average areas of the sunspot groups correspond to values for epoch of “lowered “solar activity, average magnetic field in the umbra of sunspots was reduced approximately to 700 gauss, and for this time was observed only 4 very large sunspot groups (≥1500 mvh). Flare activity substantially was lowered: for the time of the current solar cycle development it was occurrence of M-class flares M - 368, class X - 32, from which only 2 solar flares of class X> 5. Solar proton events are observed predominantly small intensity; but only 5 from them were the intensity of ≥100 pfu (S2) and 4 - ≥1000 pfu (S3). The first five years of the 24 cycle evolution confirm this assumption and the possibility to give the qualitative forecast of his evolution and development of the

Variations of Solar Non-axisymmetric Activity

Science.gov (United States)

Gyenge, N.; Baranyi, T.; Ludmány, A.

The temporal behaviour of solar active longitudes has been examined by using two sunspot catalogues, the Greenwich Photoheliographic Results (GPR) and the Debrecen Photoheliographic Data (DPD). The time-longitude diagrams of the activity distribution reveal the preferred longitudinal zones and their migration with respect to the Carrington frame. The migration paths outline a set of patterns in which the activity zone has alternating prograde/retrograde angular velocities with respect to the Carrington rotation rate. The time profiles of these variations can be described by a set of successive parabolae. Two similar migration paths have been selected from these datasets, one northern path during cycles 21 - 22 and one southern path during cycles 13 - 14, for closer examination and comparison of their dynamical behaviours. The rates of sunspot emergence exhibited in both migration paths similar periodicities, close to 1.3 years. This behaviour may imply that the active longitude is connected to the bottom of convection zone.

Does solar activity affect human happiness?

Science.gov (United States)

Kristoufek, Ladislav

2018-03-01

We investigate the direct influence of solar activity (represented by sunspot numbers) on human happiness (represented by the Twitter-based Happiness Index). We construct four models controlling for various statistical and dynamic effects of the analyzed series. The final model gives promising results. First, there is a statistically significant negative influence of solar activity on happiness which holds even after controlling for the other factors. Second, the final model, which is still rather simple, explains around 75% of variance of the Happiness Index. Third, our control variables contribute significantly as well: happiness is higher in no sunspots days, happiness is strongly persistent, there are strong intra-week cycles and happiness peaks during holidays. Our results strongly contribute to the topical literature and they provide evidence of unique utility of the online data.

Solar wind and coronal structure near sunspot minimum: Pioneer and SMM observations from 1985-1987

International Nuclear Information System (INIS)

Mihalov, J.D.; Barnes, A.; Hundhausen, A.J.; Smith, E.J.

1990-01-01

The solar wind speeds observed in the outer heliosphere (20 to 40 AU heliocentric distance, approximately) by Pioneers 10 an 11, and at a heliocentric distance of 0.7 AU by the Pioneer Venus spacecraft, reveal a complex set of changes in the years near the recent sunspot minimum, 1985-1987. The pattern of recurrent solar wind streams, the long-term average speed, and the sector polarity of the interplanetary magnetic field all changed in a manner suggesting both a temporal variation, and a changing dependence on heliographic latitude. Coronal observations made from the Solar Maximum Mission spacecraft during the same epoch show a systematic variation in coronal structure and (by implication) the magnetic structure imposed on the expanding solar wind. These observations suggest interpretation of the solar wind speed variations in terms of the familiar model where the speed increases with distance from a nearly flat interplanetary current sheet (or with heliomagnetic latitude), and where this current sheet becomes aligned with the solar equatorial plane as sunspot minimum approaches, but deviates rapidly from that orientation after minimum. The authors confirm here that this basic organization of the solar wind speed persists in the outer heliosphere with an orientation of the neutral sheet consistent with that inferred at a heliocentric distance of a few solar radii, from the coronal observations

THE MINIMUM OF SOLAR CYCLE 23: AS DEEP AS IT COULD BE?

Energy Technology Data Exchange (ETDEWEB)

Muñoz-Jaramillo, Andrés; Longcope, Dana W. [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Senkpeil, Ryan R. [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States); Tlatov, Andrey G. [Kislovodsk Mountain Astronomical Station of the Pulkovo Observatory, Kislovodsk 357700 (Russian Federation); Pevtsov, Alexei A. [National Solar Observatory, Sunspot, NM 88349 (United States); Balmaceda, Laura A. [Institute for Astronomical, Terrestrial and Space Sciences (ICATE-CONICET), San Juan (Argentina); DeLuca, Edward E. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Martens, Petrus C. H., E-mail: munoz@solar.physics.montana.edu [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303 (United States)

2015-05-01

In this work we introduce a new way of binning sunspot group data with the purpose of better understanding the impact of the solar cycle on sunspot properties and how this defined the characteristics of the extended minimum of cycle 23. Our approach assumes that the statistical properties of sunspots are completely determined by the strength of the underlying large-scale field and have no additional time dependencies. We use the amplitude of the cycle at any given moment (something we refer to as activity level) as a proxy for the strength of this deep-seated magnetic field. We find that the sunspot size distribution is composed of two populations: one population of groups and active regions and a second population of pores and ephemeral regions. When fits are performed at periods of different activity level, only the statistical properties of the former population, the active regions, are found to vary. Finally, we study the relative contribution of each component (small-scale versus large-scale) to solar magnetism. We find that when hemispheres are treated separately, almost every one of the past 12 solar minima reaches a point where the main contribution to magnetism comes from the small-scale component. However, due to asymmetries in cycle phase, this state is very rarely reached by both hemispheres at the same time. From this we infer that even though each hemisphere did reach the magnetic baseline, from a heliospheric point of view the minimum of cycle 23 was not as deep as it could have been.

Active regions, ch. 7

International Nuclear Information System (INIS)

Martres, M.J.; Bruzek, A.

1977-01-01

The solar Active Region is an extremely complex phenomenon comprising a large variety of features (active,region phenomena) in the photosphere, chromosphere and corona. The occurrence of the various active phenomena depends on the phase and state of evolution of the AR; their appearance depends on the radiation used for the observation. The various phenomena are described and illustrated with photographs. Several paragraphs are dedicated to magnetic classification of AR, Mt. Wilson Spot Classification, solar activity indices, and solar activity data publications

Polarization reversal during the solar noise storm activity of August 1971

International Nuclear Information System (INIS)

Kurihara, Masahiro

1975-01-01

Reversals of the sense of circular polarization of solar radio emission were observed for active type I storms in August 1971. Observations with a 160-MHz interferometer revealed that the reversals were caused by sudden growth and decay of a secondary storm source whose sense of polarization was opposite to that of the long-lasting main source. The time variations of both the associated S-component sources and sunspots are compared with that of the storm sources. The role of the magnetic field, which presumably connects the storm sources, the S-component sources, and the sunspots, is discussed in relation to the origin of the storm activity. (author)

Normal and counter Evershed flows in the photospheric penumbra of a sunspot SPINOR 2D inversions of Hinode-SOT/SP observations

Czech Academy of Sciences Publication Activity Database

Siu-Tapia, A.; Lagg, A.; Solanki, S.K.; van Noort, M.; Jurčák, Jan

2017-01-01

Roč. 607, November (2017), A36/1-A36/17 E-ISSN 1432-0746 Institutional support: RVO:67985815 Keywords : sunspots * photosphere * magnetic fields Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics OBOR OECD: Astronomy (including astrophysics,space science) Impact factor: 5.014, year: 2016

On the Theory of Sunspots Proposed by Signor Kirchoff

Directory of Open Access Journals (Sweden)

Secchi A.

2011-07-01

Full Text Available Eileen Reeves (Department of Comparative Literature, Princeton University, Princeton, New Jersey, 08544 and Mary Posani (Department of French and Italian, The Ohio State University, Columbus, Ohio, 43221 provide a translation of Father Pietro Angelo Secchi’s classic work “ Secchi A. Sulla Teoria Delle Macchie Solari: Proposta dal sig. Kirchoff” as it appeared in Bullettino Meteorologico dell’ Osservatorio del Collegio Romano , 31 January 1864, v.3(4, 1–4. This was the first treatise to propose a partic- ulate photosphere floating on the gaseous body of the Sun. The idea would dominate astrophysical thought for the next 50 years. Secchi appears to have drafted the article, as a response to Gustav Kirchhoff’s proposal, echoing early Galilean ideas, that sunspots represented clouds which floated above the photosphere. Other than presenting a new solar model, noteworthy aspects of this work include Secchi’s appropriate insistence that materials do not emit the same light at the same temperature and his gentle rebuke of Kirchhoff relative to commenting on questions of astronomy.

Open magnetic fields in active regions

Science.gov (United States)

Svestka, Z.; Solodyna, C. V.; Howard, R.; Levine, R. H.

1977-01-01

Soft X-ray images and magnetograms of several active regions and coronal holes are examined which support the interpretation that some of the dark X-ray gaps seen between interconnecting loops and inner cores of active regions are foot points of open field lines inside the active regions. Characteristics of the investigated dark gaps are summarized. All the active regions with dark X-ray gaps at the proper place and with the correct polarity predicted by global potential extrapolation of photospheric magnetic fields are shown to be old active regions, indicating that field opening is accomplished only in a late phase of active-region development. It is noted that some of the observed dark gaps probably have nothing in common with open fields, but are either due to the decreased temperature in low-lying portions of interconnecting loops or are the roots of higher and less dense or cooler loops.

Period of sunspot numbers is 11. 02653720 years (11 years 9 days 16 hours 18 minutes 0 seconds)

Energy Technology Data Exchange (ETDEWEB)

Norita, S [Miyazaki Univ. (Japan). Faculty of Engineering

1976-09-01

In the statistical analysis of time series there have been applied usually the stationary stochastic process or the Markov stochastic process and recently there are applied remarkably an autoregressive process, a stochastic difference equation, an autoregressive-moving average process, a moving average process, the Whittaker periodogram, the correlogram, Schuster periodogram, chi-squared periodogram, level crossings, harmonic process, difference method, spectral density and first order vector equation, but in special case it is desirable to apply the nonstationary stocastic process. In this paper we introduce a stationarity into the autoregressive process and then it is the first purpose to compute precisely the period of sunspot numbers. The result up to the eighth places at the decimal point was obtained that its period is 11.02653720 years, that is, 11 years 9 days 16 hours 18 minutes 0 seconds. This is considered to be more relevant than numerical values by which Schuster (1906) and Yule (1927) had calculated the respective 11.125 years and 10.60 years in the past. We revised the theoretical expression in the thesis of Anderson, Shaman, Lindgren, Brillinger, Newbold, Parzen, Kingman, Van Ness and Kenneth, etc. and executed the numerical analysis of period of sunspot numbers investigated now.

Period of sunspot numbers is 11.02653720 years (11 years 9 days 16 hours 18 minutes 0 seconds)

International Nuclear Information System (INIS)

Norita, Sadataka

1976-01-01

In the statistical analysis of time series there have been applied usually the stationary stochastic process or the Markov stochastic process and recently there are applied remarkably an autoregressive process, a stochastic difference equation, an autoregressive-moving average process, a moving average process, the Whittaker periodogram, the correlogram, Schuster periodogram, chi-squared periodogram, level crossings, harmonic process, difference method, spectral density and first order vector equation, but in special case it is desirable to apply the nonstationary stocastic process. In this paper we introduce an stationarity into the autoregressive process and then it is the first purpose to compute precisely period of sunspot numbers. The result up to the eighth places at the decimal point was obtained that its period is 11.02653720 years, that is, 11 years 9 days 16 hours 18 minutes 0 seconds. This is considered to be more relevant than numerical values by which Schuster (1906) and Yule (1927) had calculated the respective 11.125 years and 10.60 years in the past. We revised the theoretical expression in the thesis of Anderson, Shaman, Lindgren, Brillinger, Newbold, Parzen, Kingman, Van Ness and Kenneth, etc. and executed the numerical analysis of period of sunspot numbers investigated now. (auth.)

Morphology of F-region vertical E×B drifts in the African sector using ionosonde measurements

Directory of Open Access Journals (Sweden)

C. C. Oluwafemi

2007-06-01

Full Text Available F-region vertical velocities are derived from the ground-based ionosonde data for Ibadan (7.4°N, 3.9°E; dip 6°S: an equatorial station in the African zone, to study the general characteristics of electrodynamics of equatorial ionosphere, such as their variation with season, solar cycle, and magnetic activity at different local time sectors. The results show profound seasonal and geomagnetic effects. Except for equinoctial period, there is an excellent consistency in the magnitudes (nearly 20 m/s and patterns of upward daytime F-region drifts at low and high solar activity periods. Evening F-region exhibits strong motion with absolute mean value for quiet-time (15 m/s greater than on disturbed-time (10 m/s. The average downward quiet midnight-early morning hours sector value is well below than 10 m/s. The evening reversal time is earliest and latest during solstitial periods. Prereversal peak is season dependent and varies strongly with magnetic activity. We show that prereversal peak, daytime, and nighttime maximum drifts saturate at particular values of F10.7 cm solar radio flux index, effects not noticed with corresponding sunspot number. Our observations confirm several previous results from other equatorial sites utilizing different experimental techniques.

Recurrent Forbush decreases and relationship between active regions and M-regions

International Nuclear Information System (INIS)

Shah, G.N.; Kaul, C.L.; Razdan, H.; Bemalkhedkar, M.M.

1977-01-01

Recurrent Forbush decreases and recurrent geomagnetic disturbances have been attributed to the solar M-regions, which are sources of high velocity solar plasma streams. A study of recurrent Forbush decreases for the period 1966-75 has been made to examine any possible relationship of M-regions with solar active regions. It is shown that at the onset of the recurrent Forbush decrease at earth, there is a high probability of encountering a class of active regions at central meridian of the sun which give rise to flares of importance >= 28/3N. These active regions are found to be long-lasting and to have large areas as well as high Hsub(α)-intensities. Other active regions, producing flares of only lower importance, are distributed randomly on the sun with respect to the onset of a recurrent Forbush decrease. Using the quasiradial hypervelocity approximation, the base of the leading edge of the high velocity stream, at the onset of a recurrent Forbush decrease at earth, is traced to the solar longitude about 40 deg West of the central meridian. From these results, it is deduced that M-regions are located preferentially to the West of long-lasting, magnetically complex active regions. Earlier studies of the identification of the M-regions on the sun have been re-examined and shown to conform to this positional relationship. A possible mechanism of the development of an M-region to the West of the long-lasting magnetically complex active region is also discussed. (author)

Recent perspectives in solar physics - Elemental composition, coronal structure and magnetic fields, solar activity

Science.gov (United States)

Newkirk, G., Jr.

1975-01-01

Elemental abundances in the solar corona are studied. Abundances in the corona, solar wind and solar cosmic rays are compared to those in the photosphere. The variation in silicon and iron abundance in the solar wind as compared to helium is studied. The coronal small and large scale structure is investigated, emphasizing magnetic field activity and examining cosmic ray generation mechanisms. The corona is observed in the X-ray and EUV regions. The nature of coronal transients is discussed with emphasis on solar-wind modulation of galactic cosmic rays. A schematic plan view of the interplanetary magnetic field during sunspot minimum is given showing the presence of magnetic bubbles and their concentration in the region around 4-5 AU by a fast solar wind stream.

Are cold winters in Europe associated with low solar activity?

International Nuclear Information System (INIS)

Lockwood, M; Harrison, R G; Woollings, T; Solanki, S K

2010-01-01

Solar activity during the current sunspot minimum has fallen to levels unknown since the start of the 20th century. The Maunder minimum (about 1650-1700) was a prolonged episode of low solar activity which coincided with more severe winters in the United Kingdom and continental Europe. Motivated by recent relatively cold winters in the UK, we investigate the possible connection with solar activity. We identify regionally anomalous cold winters by detrending the Central England temperature (CET) record using reconstructions of the northern hemisphere mean temperature. We show that cold winter excursions from the hemispheric trend occur more commonly in the UK during low solar activity, consistent with the solar influence on the occurrence of persistent blocking events in the eastern Atlantic. We stress that this is a regional and seasonal effect relating to European winters and not a global effect. Average solar activity has declined rapidly since 1985 and cosmogenic isotopes suggest an 8% chance of a return to Maunder minimum conditions within the next 50 years (Lockwood 2010 Proc. R. Soc. A 466 303-29): the results presented here indicate that, despite hemispheric warming, the UK and Europe could experience more cold winters than during recent decades.

ALMA Discovery of Solar Umbral Brightness Enhancement at λ = 3 mm

Energy Technology Data Exchange (ETDEWEB)

Iwai, Kazumasa [Institute for Space-Earth Environmental Research, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601 (Japan); Loukitcheva, Maria [Center for Solar-Terrestrial Research, New Jersey Institute of Technology, 323 Martin Luther King Boulevard, Newark, NJ 07102 (United States); Shimojo, Masumi [Chile Observatory, National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Solanki, Sami K. [Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, D-37073 Göttingen (Germany); White, Stephen M., E-mail: k.iwai@isee.nagoya-u.ac.jp [Space Vehicles Directorate, Air Force Research Laboratory, Albuquerque, NM (United States)

2017-06-01

We report the discovery of a brightness enhancement in the center of a large sunspot umbra at a wavelength of 3 mm using the Atacama Large Millimeter/sub-millimeter Array (ALMA). Sunspots are among the most prominent features on the solar surface, but many of their aspects are surprisingly poorly understood. We analyzed a λ = 3 mm (100 GHz) mosaic image obtained by ALMA that includes a large sunspot within the active region AR12470, on 2015 December 16. The 3 mm map has a 300″ × 300″ field of view and 4.″9 × 2.″2 spatial resolution, which is the highest spatial resolution map of an entire sunspot in this frequency range. We find a gradient of 3 mm brightness from a high value in the outer penumbra to a low value in the inner penumbra/outer umbra. Within the inner umbra, there is a marked increase in 3 mm brightness temperature, which we call an umbral brightness enhancement. This enhanced emission corresponds to a temperature excess of 800 K relative to the surrounding inner penumbral region and coincides with excess brightness in the 1330 and 1400 Å slit-jaw images of the Interface Region Imaging Spectrograph ( IRIS ), adjacent to a partial lightbridge. This λ = 3 mm brightness enhancement may be an intrinsic feature of the sunspot umbra at chromospheric heights, such as a manifestation of umbral flashes, or it could be related to a coronal plume, since the brightness enhancement was coincident with the footpoint of a coronal loop observed at 171 Å.

Stokes profile analysis and vector magnetic fields. III. Extended temperature minima of sunspot umbrae as inferred from Stokes profiles of Mg I 4571 A

International Nuclear Information System (INIS)

Lites, B.W.; Skumanich, A.; Rees, D.E.; Murphy, G.A.; Carlsson, M.; Sydney Univ., Australia; Oslo Universitetet, Norway)

1987-01-01

Observed Stokes profiles of Mg I 4571 A are analyzed as a diagnostic of the magnetic field and thermal structure at the temperature minimum of sunspot umbrae. Multilevel non-LTE transfer calculations of the Mg I-II-III excitation and ionization balance in model umbral atmospheres show: (1) Mg I to be far less ionized in sunspot umbrae than in the quiet sun, leading to greatly enhanced opacity in 4571 A, and (2) LTE excitation of 4571 A. Existing umbral models predict emission cores of the Stokes I profile due to the chromospheric temperature rise. This feature is not present in observed umbral profiles. Moreover, such an emission reversal causes similar anomalous features in the Stokes Q, U, V profiles, which are also not observed. Umbral atmospheres with extended temperature minima are suggested. Implications for chromospheric heating mechanisms and the utility of this line for solar vector magnetic field measurements are discussed. 35 references

Recurrent forbush decreases and the relationship between active regions and M regions

International Nuclear Information System (INIS)

Shah, G.N.; Kaul, C.L.; Razdan, H.; Bemalkhedkar, M.M.

1978-01-01

Recurrent Forbush decreases and recurrent geomagnetic disturbances have been attributed to the solar M regions, which are sources of high-velocity solar plasma streams. A study of recurrent Forbush decreases for the period 1966--1975 has been made to examine any possible relationship of M regions with solar active regions. It is shown that at the onset of the recurrent Forbush decrease at the earth there is a high probability of encountering a class of active regions at the central meridian of the sun which give rise to flares of importance > or =2B/3N. These active regions are found to be long lasting and to have large areas as well as high Hα intensities. Other active regions, producing flares of lower importance, are distributed randomly on the sun with respect to the onset of a recurrent Forbush decrease. By using the quasi-radial hypervelocity approximation the base of the leading edge of the high-velocity stream at the onset of a recurrent Forbush decrease at the earth is traced to the solar longitude about 40 0 west of the central meridan. From these results it is deduced that M regions are located preferentially to the west of long-lasting magnetically complex active regions. Earlier studies of the identification of the M regions on the sun have been reexamined and shown to conform to this positional relationship. A possible mechanism of the development of an M region to the west of the long-lasting magnetically complex active region is also discussed

An econometric investigation of the sunspot number record since the year 1700 and its prediction into the 22nd century

Science.gov (United States)

Travaglini, Guido

2015-09-01

Solar activity, as measured by the yearly revisited time series of sunspot numbers (SSN) for the period 1700-2014 (Clette et al., 2014), undergoes in this paper a triple statistical and econometric checkup. The conclusions are that the SSN sequence: (1) is best modeled as a signal that features nonlinearity in mean and variance, long memory, mean reversion, 'threshold' symmetry, and stationarity; (2) is best described as a discrete damped harmonic oscillator which linearly approximates the flux-transport dynamo model; (3) its prediction well into the 22nd century testifies of a substantial fall of the SSN centered around the year 2030. In addition, the first and last Gleissberg cycles show almost the same peak number and height during the period considered, yet the former slightly prevails when measured by means of the estimated smoother. All of these conclusions are achieved by making use of modern tools developed in the field of Financial Econometrics and of two new proposed procedures for signal smoothing and prediction.

Periodic Variation of the North-South Asymmetry of Solar Activity ...

Indian Academy of Sciences (India)

Abstract. We report here a study of various solar activity phenomena occurring in both north and south hemispheres of the Sun during solar cycles 8-23. In the study we have used sunspot data for the period 1832—. 1976, flare index data for the period 1936-1993, Hα flare data 1993-1998 and solar active prominences data ...

Polar coronal holes and solar cycles

International Nuclear Information System (INIS)

Simon, P.A.

1979-01-01

The relationship between the geomagnetic activity of the three years preceding a sunspot minimum and the peak of the next sunspot maximum confirms the polar origin of the solar wind during one part of the solar cycle. Pointing out that the polar holes have a very small size or disappear at the time of the polar field reversal, a low latitude origin of the solar-wind at sunspot maximum is suggested and the cycle variation of solar wind and geomagnetic activity is described. In addition a close relationship is noted between the maximum level of the geomagnetic activity reached a few years before a solar minimum and its level at the next sunspot maximum. Studying separately the effects of both the low latitude holes and the solar activity, the possibility of predicting both the level of geomagnetic activity and the sunspot number at the next sunspot maximum is pointed out. As a conclusion the different categories of phenomena contributing to a solar cycle are specified. (Auth.)

Detailed analysis of dynamic evolution of three Active Regions at the photospheric level before flare and CME occurrence

Science.gov (United States)

Ye, Yudong; Korsós, M. B.; Erdélyi, R.

2018-01-01

We present a combined analysis of the applications of the weighted horizontal magnetic gradient (denoted as WGM in Korsós et al. (2015)) method and the magnetic helicity tool (Berger and Field, 1984) employed for three active regions (ARs), namely NOAA AR 11261, AR 11283 and AR 11429. We analysed the time series of photospheric data from the Solar Dynamics Observatory taken between August 2011 and March 2012. During this period the three ARs produced a series of flares (eight M- and six X-class) and coronal mass ejections (CMEs). AR 11261 had four M-class flares and one of them was accompanied by a fast CME. AR 11283 had similar activities with two M- and two X-class flares, but only with a slow CME. Finally, AR 11429 was the most powerful of the three ARs as it hosted five compact and large solar flare and CME eruptions. For applying the WGM method we employed the Debrecen sunspot data catalogue, and, for estimating the magnetic helicity at photospheric level we used the Space-weather HMI Active Region Patches (SHARP's) vector magnetograms from SDO/HMI (Solar Dynamics Observatory/Helioseismic and Magnetic Imager). We followed the evolution of the components of the WGM and the magnetic helicity before the flare and CME occurrences. We found a unique and mutually shared behaviour, called the U-shaped pattern, of the weighted distance component of WGM and of the shearing component of the helicity flux before the flare and CME eruptions. This common pattern is associated with the decreasing-receding phases yet reported only known to be a necessary feature prior to solar flare eruption(s) but found now at the same time in the evolution of the shearing helicity flux. This result leads to the conclusions that (i) the shearing motion of photospheric magnetic field may be a key driver for solar eruption in addition to the flux emerging process, and that (ii) the found decreasing-approaching pattern in the evolution of shearing helicity flux may be another precursor

High-resolution imaging and near-infrared spectroscopy of penumbral decay

Science.gov (United States)

Verma, M.; Denker, C.; Balthasar, H.; Kuckein, C.; Rezaei, R.; Sobotka, M.; Deng, N.; Wang, H.; Tritschler, A.; Collados, M.; Diercke, A.; Manrique, S. J. González

2018-06-01

Aims: Combining high-resolution spectropolarimetric and imaging data is key to understanding the decay process of sunspots as it allows us to scrutinize the velocity and magnetic fields of sunspots and their surroundings. Methods: Active region NOAA 12597 was observed on 2016 September 24 with the 1.5-meter GREGOR solar telescope using high-spatial-resolution imaging as well as imaging spectroscopy and near-infrared (NIR) spectropolarimetry. Horizontal proper motions were estimated with local correlation tracking, whereas line-of-sight (LOS) velocities were computed with spectral line fitting methods. The magnetic field properties were inferred with the "Stokes Inversions based on Response functions" (SIR) code for the Si I and Ca I NIR lines. Results: At the time of the GREGOR observations, the leading sunspot had two light bridges indicating the onset of its decay. One of the light bridges disappeared, and an elongated, dark umbral core at its edge appeared in a decaying penumbral sector facing the newly emerging flux. The flow and magnetic field properties of this penumbral sector exhibited weak Evershed flow, moat flow, and horizontal magnetic field. The penumbral gap adjacent to the elongated umbral core and the penumbra in that penumbral sector displayed LOS velocities similar to granulation. The separating polarities of a new flux system interacted with the leading and central part of the already established active region. As a consequence, the leading spot rotated 55° clockwise over 12 h. Conclusions: In the high-resolution observations of a decaying sunspot, the penumbral filaments facing the flux emergence site contained a darkened area resembling an umbral core filled with umbral dots. This umbral core had velocity and magnetic field properties similar to the sunspot umbra. This implies that the horizontal magnetic fields in the decaying penumbra became vertical as observed in flare-induced rapid penumbral decay, but on a very different time-scale.

STUDY OF RAPID FORMATION OF A δ SUNSPOT ASSOCIATED WITH THE 2012 JULY 2 C7.4 FLARE USING HIGH-RESOLUTION OBSERVATIONS OF THE NEW SOLAR TELESCOPE

International Nuclear Information System (INIS)

Wang Haimin; Liu Chang; Wang Shuo; Deng Na; Xu Yan; Jing Ju; Cao Wenda

2013-01-01

Rapid, irreversible changes of magnetic topology and sunspot structure associated with flares have been systematically observed in recent years. The most striking features include the increase of the horizontal field at the polarity inversion line (PIL) and the co-spatial penumbral darkening. A likely explanation of the above phenomenon is the back reaction to the coronal restructuring after eruptions: a coronal mass ejection carries the upward momentum while the downward momentum compresses the field lines near the PIL. Previous studies could only use low-resolution (above 1'') magnetograms and white-light images. Therefore, the changes are mostly observed for X-class flares. Taking advantage of the 0.''1 spatial resolution and 15 s temporal cadence of the New Solar Telescope at the Big Bear Solar Observatory, we report in detail the rapid formation of sunspot penumbra at the PIL associated with the C7.4 flare on 2012 July 2. It is unambiguously shown that the solar granulation pattern evolves to an alternating dark and bright fibril structure, the typical pattern of penumbra. Interestingly, the appearance of such a penumbra creates a new δ sunspot. The penumbral formation is also accompanied by the enhancement of the horizontal field observed using vector magnetograms from the Helioseismic and Magnetic Imager. We explain our observations as being due to the eruption of a flux rope following magnetic cancellation at the PIL. Subsequently, the re-closed arcade fields are pushed down toward the surface to form the new penumbra. NLFFF extrapolation clearly shows both the flux rope close to the surface and the overlying fields

Solar Open Flux Migration from Pole to Pole: Magnetic Field Reversal.

Science.gov (United States)

Huang, G-H; Lin, C-H; Lee, L C

2017-08-25

Coronal holes are solar regions with low soft X-ray or low extreme ultraviolet intensities. The magnetic fields from coronal holes extend far away from the Sun, and thus they are identified as regions with open magnetic field lines. Coronal holes are concentrated in the polar regions during the sunspot minimum phase, and spread to lower latitude during the rising phase of solar activity. In this work, we identify coronal holes with outward and inward open magnetic fluxes being in the opposite poles during solar quiet period. We find that during the sunspot rising phase, the outward and inward open fluxes perform pole-to-pole trans-equatorial migrations in opposite directions. The migration of the open fluxes consists of three parts: open flux areas migrating across the equator, new open flux areas generated in the low latitude and migrating poleward, and new open flux areas locally generated in the polar region. All three components contribute to the reversal of magnetic polarity. The percentage of contribution from each component is different for different solar cycle. Our results also show that the sunspot number is positively correlated with the lower-latitude open magnetic flux area, but negatively correlated with the total open flux area.

Open magnetic fields in active regions

International Nuclear Information System (INIS)

Svestka, Z.; Solodyna, C.V.; Levine, R.H.

1977-01-01

Soft X-ray observations confirm that some of the dark gaps seen between interconnecting loops and inner cores of active regions may be loci of open fields, as it has been predicted by global potential extrapolation of photospheric magnetic fields. It seems that the field lines may open only in a later state of the active region development. (Auth.)

The Limit of Free Magnetic Energy in Active Regions

Science.gov (United States)

Moore, Ron; Falconer, David; Sterling, Alphonse

2012-01-01

By measuring from active-region magnetograms a proxy of the free energy in the active region fs magnetic field, it has been found previously that (1) there is an abrupt upper limit to the free energy the field can hold that increases with the amount of magnetic field in the active region, the active region fs magnetic flux content, and (2) the free energy is usually near its limit when the field explodes in a CME/flare eruption. That is, explosive active regions are concentrated in a main-sequence path bordering the free-energy ]limit line in (flux content, free-energy proxy) phase space. Here, from measurement of Marshall Space Flight Center vector magnetograms, we find the magnetic condition that underlies the free ]energy limit and the accompanying main sequence of explosive active regions. Using a suitable free ]energy proxy measured from vector magnetograms of 44 active regions, we find that (1) in active regions at and near their free ]energy limit, the ratio of magnetic-shear free energy to the non ]free magnetic energy the potential field would have is approximately 1 in the core field, the field rooted along the neutral line, and (2) this ratio is progressively less in active regions progressively farther below their free ]energy limit. This shows that most active regions in which this core-field energy ratio is much less than 1 cannot be triggered to explode; as this ratio approaches 1, most active regions become capable of exploding; and when this ratio is 1 or greater, most active regions are compelled to explode. From these results we surmise the magnetic condition that determines the free ]energy limit is the ratio of the free magnetic energy to the non-free energy the active region fs field would have were it completely relaxed to its potential ]field configuration, and that this ratio is approximately 1 at the free-energy limit and in the main sequence of explosive active regions.

Phosalone-Induced Changes in Regional Cholinesterase Activities ...

African Journals Online (AJOL)

... in Regional Cholinesterase Activities in Rat Brain during Behavioral Tolerance. ... lead to the gradual disappearance of the initial signs of toxicity over time, termed ... regions, striatum recorded a greater decrease in cholinesterase activity.

NONLINEAR PREDICTION OF SOLAR CYCLE 24

International Nuclear Information System (INIS)

Kilcik, A.; Anderson, C. N. K.; Ye, H.; Sugihara, G.; Rozelot, J. P.; Ozguc, A.

2009-01-01

Sunspot activity is highly variable and challenging to forecast. Yet forecasts are important, since peak activity has profound effects on major geophysical phenomena including space weather (satellite drag, telecommunications outages) and has even been correlated speculatively with changes in global weather patterns. This paper investigates trends in sunspot activity, using new techniques for decadal-scale prediction of the present solar cycle (cycle 24). First, Hurst exponent H analysis is used to investigate the autocorrelation structure of the putative dynamics; then the Sugihara-May algorithm is used to predict the ascension time and the maximum intensity of the current sunspot cycle. Here we report H = 0.86 for the complete sunspot number data set (1700-2007) and H = 0.88 for the reliable sunspot data set (1848-2007). Using the Sugihara-May algorithm analysis, we forecast that cycle 24 will reach its maximum in 2012 December at approximately 87 sunspot units.

A theory of the Earth's magnetic field and of sunspots, based on a self-excited dynamo incorporating the Hall effect

Directory of Open Access Journals (Sweden)

A. de Paor

2001-01-01

Full Text Available A new viewpoint on the generation and maintenance of the Earth's magnetic field is put forward, which integrates self-exciting dynamo theory with the possibility of energy coupling along orthogonal axes provided by the Hall effect. A nonlinear third-order system is derived, with a fourth equation serving as an observer of unspecified geophysical processes which could result in field reversal. Lyapunov analysis proves that chaos is not intrinsic to this system. Relative constancy of one of the variables produces pseudo equilibrium in a second order subsystem and allows for self-excitation of the geomagnetic field. Electromagnetic analysis yields expressions for key parameters. Models for secular variations recorded at London, Palermo and at the Cape of Good Hope over the past four hundred years are offered. Offset of the Earth's magnetic axis from the geographic axis is central to time-varying declination, but its causes have not yet been established. Applicability of the model to the explanation of sunspot activity is outlined. A corroborating experiment published by Peter Barlow in 1831 is appended.

The dynamic relation between activities in the Northern and Southern solar hemispheres

Science.gov (United States)

Volobuev, D. M.; Makarenko, N. G.

2016-12-01

The north-south (N/S) asymmetry of solar activity is the most pronounced phenomenon during 11-year cycle minimums. The goal of this work is to try to interpret the asymmetry as a result of the generalized synchronization of two dynamic systems. It is assumed that these systems are localized in two solar hemispheres. The evolution of these systems is considered in the topological embeddings of a sunspot area time series obtained with the use of the Takens algorithm. We determine the coupling measure and estimate it on the time series of daily sunspot areas. The measurement made it possible to interpret the asymmetry as an exchangeable dynamic equation, in which the roles of the driver-slave components change in time for two hemispheres.

STATISTICAL ANALYSIS OF ACOUSTIC WAVE PARAMETERS NEAR SOLAR ACTIVE REGIONS

International Nuclear Information System (INIS)

Rabello-Soares, M. Cristina; Bogart, Richard S.; Scherrer, Philip H.

2016-01-01

In order to quantify the influence of magnetic fields on acoustic mode parameters and flows in and around active regions, we analyze the differences in the parameters in magnetically quiet regions nearby an active region (which we call “nearby regions”), compared with those of quiet regions at the same disk locations for which there are no neighboring active regions. We also compare the mode parameters in active regions with those in comparably located quiet regions. Our analysis is based on ring-diagram analysis of all active regions observed by the Helioseismic and Magnetic Imager (HMI) during almost five years. We find that the frequency at which the mode amplitude changes from attenuation to amplification in the quiet nearby regions is around 4.2 mHz, in contrast to the active regions, for which it is about 5.1 mHz. This amplitude enhacement (the “acoustic halo effect”) is as large as that observed in the active regions, and has a very weak dependence on the wave propagation direction. The mode energy difference in nearby regions also changes from a deficit to an excess at around 4.2 mHz, but averages to zero over all modes. The frequency difference in nearby regions increases with increasing frequency until a point at which the frequency shifts turn over sharply, as in active regions. However, this turnover occurs around 4.9 mHz, which is significantly below the acoustic cutoff frequency. Inverting the horizontal flow parameters in the direction of the neigboring active regions, we find flows that are consistent with a model of the thermal energy flow being blocked directly below the active region.

MODELING THE INITIATION OF THE 2006 DECEMBER 13 CORONAL MASS EJECTION IN AR 10930: THE STRUCTURE AND DYNAMICS OF THE ERUPTING FLUX ROPE

Energy Technology Data Exchange (ETDEWEB)

Fan, Yuhong, E-mail: yfan@ucar.edu [High Altitude Observatory, National Center for Atmospheric Research, 3080 Center Green Drive, Boulder, CO 80301 (United States)

2016-06-20

We carry out a 3D magnetohydrodynamic simulation to model the initiation of the coronal mass ejection (CME) on 2006 December 13 in the emerging δ -sunspot active region NOAA 10930. The setup of the simulation is similar to a previous simulation by Fan, but with a significantly widened simulation domain to accommodate the wide CME. The simulation shows that the CME can result from the emergence of a east–west oriented twisted flux rope whose positive, following emerging pole corresponds to the observed positive rotating sunspot emerging against the southern edge of the dominant pre-existing negative sunspot. The erupting flux rope in the simulation accelerates to a terminal speed that exceeds 1500 km s{sup −1} and undergoes a counter-clockwise rotation of nearly 180° such that its front and flanks all exhibit southward directed magnetic fields, explaining the observed southward magnetic field in the magnetic cloud impacting the Earth. With continued driving of flux emergence, the source region coronal magnetic field also shows the reformation of a coronal flux rope underlying the flare current sheet of the erupting flux rope, ready for a second eruption. This may explain the build up for another X-class eruptive flare that occurred the following day from the same region.

Indexes and parameters of activity in solar-terrestrial physics

International Nuclear Information System (INIS)

Minasyants, G.S.; Minasyants, T.M.

2005-01-01

The daily variation of different indexes and parameters of the solar-terrestrial physics at the 23 cycle were considered to find the most important from them for the forecast of geomagnetic activity. The validity of application of the Wolf numbers in quality of the characteristic of solar activity at sunspots is confirmed. The best geo-effective parameter in the arrival of the interplanetary shock from coronal mass ejection to an orbit of the Earth. (author)

Observations of f- and p-mode oscillations of high degree (500 < l < 2500) in quiet and active sun

International Nuclear Information System (INIS)

Tarbell, T.; Peri, M.; Frank, Z.; Shine, R.; Title, A.

1988-01-01

This poster presents spectra (l - υ diagrams) from high resolution observations taken at the Vacuum Tower Telescope (NSO/Sunspot). The raw data are CCD images taken through the SOUP narrowband filter in Fe I 5576 A. Four filtergrams spaced through the spectral line are combined to form velocity movies. Spectra for 80 minutes of data with 0.5 - 1.5 arcsecond resolution are presented for the entire field-of-view and for quiet and magnetic subregions. Ridges f and p 1 - p 5 are evident in velocity spectra, extending to l = 2500 (f), l = 1800 (p 1 ), and l = 1200 (p 2 ). Much less power is seen in the magnetic region than in the quiet sun. Three-dimensional Fourier filtering shows that oscillation velocity amplitude drops sharply at the boundary of the active region for each family of modes considered

Mutual attraction of magnetic knots

International Nuclear Information System (INIS)

Parker, E.N.

1978-01-01

It is observed that the magnetic knots associated with active regions on the Sun have an attraction for each other during the formative period of the active regions, when new magnetic flux is coming to the surface. The attraction disappears when new flux ceases to rise through the surface. Then the magnetic spots and knots tend to come apart, leading to disintegration of the sunspots previously formed. The dissolution of the fields is to be expected, as a consequence of the magnetic repulsion of knots of like polarity and as a consequence of the hydromagnetic exchange instability.The purpose of this paper is to show that the mutual attraction of knots during the formative stages of a sunspot region may be understood as the mutual hydrodynamic attraction of the rising flux tubes. Two rising tubes attract each other, as a consequence of the wake of the leading tube when one is moving behind the other, and as a consequence of the Bernoulli effect when rising side by side

Journal of Astrophysics and Astronomy | Indian Academy of Sciences

Indian Academy of Sciences (India)

2016-01-27

Jan 27, 2016 ... Helicity of Solar Active Regions from a Dynamo Model .... of the magnetic field, the amount of possible free energy storage, ... Flare Ribbon Expansion and Energy Release .... The Flares Associated with the Dynamics of the Sunspots .... Spatial Damping of Linear Compressional Magnetoacoustic Waves in ...

Complex network approach to characterize the statistical features of the sunspot series

International Nuclear Information System (INIS)

Zou, Yong; Liu, Zonghua; Small, Michael; Kurths, Jürgen

2014-01-01

Complex network approaches have been recently developed as an alternative framework to study the statistical features of time-series data. We perform a visibility-graph analysis on both the daily and monthly sunspot series. Based on the data, we propose two ways to construct the network: one is from the original observable measurements and the other is from a negative-inverse-transformed series. The degree distribution of the derived networks for the strong maxima has clear non-Gaussian properties, while the degree distribution for minima is bimodal. The long-term variation of the cycles is reflected by hubs in the network that span relatively large time intervals. Based on standard network structural measures, we propose to characterize the long-term correlations by waiting times between two subsequent events. The persistence range of the solar cycles has been identified over 15–1000 days by a power-law regime with scaling exponent γ = 2.04 of the occurrence time of two subsequent strong minima. In contrast, a persistent trend is not present in the maximal numbers, although maxima do have significant deviations from an exponential form. Our results suggest some new insights for evaluating existing models. (paper)

On the possible relations between solar activities and global seismicity in the solar cycle 20 to 23

Energy Technology Data Exchange (ETDEWEB)

Herdiwijaya, Dhani, E-mail: dhani@as.itb.ac.id [Astronomy Research Division and Bosscha Observatory, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, Ganesha 10, Bandung, Indonesia 40132 (Indonesia); Arif, Johan [Geology Research Division, Faculty of Earth Sciences and Technology, Bandung Institute of Technology, Ganesha 10, Bandung, Indonesia 40132 (Indonesia); Nurzaman, Muhamad Zamzam; Astuti, Isna Kusuma Dewi [Astronomy Study Program, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, Ganesha 10, Bandung, Indonesia 40132 (Indonesia)

2015-09-30

Solar activities consist of high energetic particle streams, electromagnetic radiation, magnetic and orbital gravitational forces. The well-know solar activity main indicator is the existence of sunspot which has mean variation in 11 years, named by solar cycle, allow for the above fluctuations. Solar activities are also related to the space weather affecting all planetary atmospheric variability, moreover to the Earth’s climate variability. Large extreme space and geophysical events (high magnitude earthquakes, explosive volcanic eruptions, magnetic storms, etc.) are hazards for humankind, infrastructure, economies, technology and the activities of civilization. With a growing world population, and with modern reliance on delicate technological systems, human society is becoming increasingly vulnerable to natural hazardous events. The big question arises to the relation between solar forcing energy to the Earth’s global seismic activities. Estimates are needed for the long term occurrence-rate probabilities of these extreme natural hazardous events. We studied connectivity from yearly seismic activities that refer to and sunspot number within the solar cycle 20 to 23 of year 1960 to 2013 (53 years). We found clear evidences that in general high magnitude earthquake events and their depth were related to the low solar activity.

On the possible relations between solar activities and global seismicity in the solar cycle 20 to 23

Science.gov (United States)

Herdiwijaya, Dhani; Arif, Johan; Nurzaman, Muhamad Zamzam; Astuti, Isna Kusuma Dewi

2015-09-01

Solar activities consist of high energetic particle streams, electromagnetic radiation, magnetic and orbital gravitational forces. The well-know solar activity main indicator is the existence of sunspot which has mean variation in 11 years, named by solar cycle, allow for the above fluctuations. Solar activities are also related to the space weather affecting all planetary atmospheric variability, moreover to the Earth's climate variability. Large extreme space and geophysical events (high magnitude earthquakes, explosive volcanic eruptions, magnetic storms, etc.) are hazards for humankind, infrastructure, economies, technology and the activities of civilization. With a growing world population, and with modern reliance on delicate technological systems, human society is becoming increasingly vulnerable to natural hazardous events. The big question arises to the relation between solar forcing energy to the Earth's global seismic activities. Estimates are needed for the long term occurrence-rate probabilities of these extreme natural hazardous events. We studied connectivity from yearly seismic activities that refer to and sunspot number within the solar cycle 20 to 23 of year 1960 to 2013 (53 years). We found clear evidences that in general high magnitude earthquake events and their depth were related to the low solar activity.

Active Longitude and Solar Flare Occurrences

Science.gov (United States)

Gyenge, N.; Ludmány, A.; Baranyi, T.

2016-02-01

The aim of the present work is to specify the spatio-temporal characteristics of flare activity observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and the Geostationary Operational Environmental Satellite (GOES) in connection with the behavior of the longitudinal domain of enhanced sunspot activity known as active longitude (AL). By using our method developed for this purpose, we identified the AL in every Carrington Rotation provided by the Debrecen Photoheliographic Data. The spatial probability of flare occurrence has been estimated depending on the longitudinal distance from AL in the northern and southern hemispheres separately. We have found that more than 60% of the RHESSI and GOES flares is located within +/- 36^\\circ from the AL. Hence, the most flare-productive active regions tend to be located in or close to the active longitudinal belt. This observed feature may allow for the prediction of the geo-effective position of the domain of enhanced flaring probability. Furthermore, we studied the temporal properties of flare occurrence near the AL and several significant fluctuations were found. More precisely, the results of the method are the following fluctuations: 0.8, 1.3, and 1.8 years. These temporal and spatial properties of the solar flare occurrence within the active longitudinal belts could provide us with an enhanced solar flare forecasting opportunity.

Solar wind and coronal structure near sunspot minimum - Pioneer and SMM observations from 1985-1987

Science.gov (United States)

Mihalov, J. D.; Barnes, A.; Hundhausen, A. J.; Smith, E. J.

1990-01-01

Changes in solar wind speed and magnetic polarity observed at the Pioneer spacecraft are discussed here in terms of the changing magnetic geometry implied by SMM coronagraph observations over the period 1985-1987. The pattern of recurrent solar wind streams, the long-term average speed, and the sector polarity of the interplanetary magnetic field all changed in a manner suggesting both a temporal variation, and a changing dependence on heliographic latitude. Coronal observations during this epoch show a systematic variation in coronal structure and the magnetic structure imposed on the expanding solar wind. These observations suggest interpretation of the solar wind speed variations in terms of the familiar model where the speed increases with distance from a nearly flat interplanetary current sheet, and where this current sheet becomes aligned with the solar equatorial plane as sunspot minimum approaches, but deviates rapidly from that orientation after minimum.

The Magnetic Free Energy in Active Regions

Science.gov (United States)

Metcalf, Thomas R.; Mickey, Donald L.; LaBonte, Barry J.

2001-01-01

The magnetic field permeating the solar atmosphere governs much of the structure, morphology, brightness, and dynamics observed on the Sun. The magnetic field, especially in active regions, is thought to provide the power for energetic events in the solar corona, such as solar flares and Coronal Mass Ejections (CME) and is believed to energize the hot coronal plasma seen in extreme ultraviolet or X-rays. The question remains what specific aspect of the magnetic flux governs the observed variability. To directly understand the role of the magnetic field in energizing the solar corona, it is necessary to measure the free magnetic energy available in active regions. The grant now expiring has demonstrated a new and valuable technique for observing the magnetic free energy in active regions as a function of time.

INITIATION AND ERUPTION PROCESS OF MAGNETIC FLUX ROPE FROM SOLAR ACTIVE REGION NOAA 11719 TO EARTH-DIRECTED CME

Energy Technology Data Exchange (ETDEWEB)

Vemareddy, P. [Udaipur Solar Observatory, Physical Research Laboratory, Badi Road, Dewali, Udaipur 313 001 (India); Zhang, J., E-mail: vema@prl.res.in [School of Physics, Astronomy and Computational Sciences, George Mason University, Fairfax, VA 22030 (United States)

2014-12-20

An eruption event launched from the solar active region (AR) NOAA 11719 is investigated based on coronal EUV observations and photospheric magnetic field measurements obtained from the Solar Dynamic Observatory. The AR consists of a filament channel originating from a major sunspot and its south section is associated with an inverse-S sigmoidal system as observed in Atmospheric Imaging Assembly passbands. We regard the sigmoid as the main body of the flux rope (FR). There also exists a twisted flux bundle crossing over this FR. This overlying flux bundle transforms in shape similar to kink-rise evolution, which corresponds with the rise motion of the FR. The emission measure and temperature along the FR exhibits an increasing trend with its rising motion, indicating reconnection in the thinning current sheet underneath the FR. Net magnetic flux of the AR, evaluated at north and south polarities, showed decreasing behavior whereas the net current in these fluxes exhibits an increasing trend. Because the negative (positive) flux has a dominant positive (negative) current, the chirality of AR flux system is likely negative (left handed) in order to be consistent with the chirality of inverse S-sigmoidal FR. This analysis of magnetic fields of the source AR suggests that the cancelling fluxes are prime factors of the monotonous twisting of the FR system, reaching to a critical state to trigger kink instability and rise motion. This rise motion may have led to the onset of the torus instability, resulting in an Earth-directed coronal mass ejection, and the progressive reconnection in the thinning current sheet beneath the rising FR led to the M6.5 flare.

INITIATION AND ERUPTION PROCESS OF MAGNETIC FLUX ROPE FROM SOLAR ACTIVE REGION NOAA 11719 TO EARTH-DIRECTED CME

International Nuclear Information System (INIS)

Vemareddy, P.; Zhang, J.

2014-01-01

An eruption event launched from the solar active region (AR) NOAA 11719 is investigated based on coronal EUV observations and photospheric magnetic field measurements obtained from the Solar Dynamic Observatory. The AR consists of a filament channel originating from a major sunspot and its south section is associated with an inverse-S sigmoidal system as observed in Atmospheric Imaging Assembly passbands. We regard the sigmoid as the main body of the flux rope (FR). There also exists a twisted flux bundle crossing over this FR. This overlying flux bundle transforms in shape similar to kink-rise evolution, which corresponds with the rise motion of the FR. The emission measure and temperature along the FR exhibits an increasing trend with its rising motion, indicating reconnection in the thinning current sheet underneath the FR. Net magnetic flux of the AR, evaluated at north and south polarities, showed decreasing behavior whereas the net current in these fluxes exhibits an increasing trend. Because the negative (positive) flux has a dominant positive (negative) current, the chirality of AR flux system is likely negative (left handed) in order to be consistent with the chirality of inverse S-sigmoidal FR. This analysis of magnetic fields of the source AR suggests that the cancelling fluxes are prime factors of the monotonous twisting of the FR system, reaching to a critical state to trigger kink instability and rise motion. This rise motion may have led to the onset of the torus instability, resulting in an Earth-directed coronal mass ejection, and the progressive reconnection in the thinning current sheet beneath the rising FR led to the M6.5 flare

Chromospheric Plasma Ejections in a Light Bridge of a Sunspot

Energy Technology Data Exchange (ETDEWEB)

Song, Donguk; Chae, Jongchul; Yang, Heesu; Cho, Kyuhyoun; Kwak, Hannah [Astronomy Program, Department of Physics and Astronomy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826 (Korea, Republic of); Yurchyshyn, Vasyl [Big Bear Solar Observatory, New Jersey Institute of Technology, 40386 North Shore Lane, Big Bear City, CA 92314-9672 (United States); Lim, Eun-Kyung; Cho, Kyung-Suk, E-mail: dusong@astro.snu.ac.kr [Korea Astronomy and Space Science Institute 776, Daedeokdae-ro, Yuseong-gu, Daejeon 34055 (Korea, Republic of)

2017-02-01

It is well-known that light bridges (LBs) inside a sunspot produce small-scale plasma ejections and transient brightenings in the chromosphere, but the nature and origin of such phenomena are still unclear. Utilizing the high-spatial and high-temporal resolution spectral data taken with the Fast Imaging Solar Spectrograph and the TiO 7057 Å broadband filter images installed at the 1.6 m New Solar Telescope of Big Bear Solar Observatory, we report arcsecond-scale chromospheric plasma ejections (1.″7) inside a LB. Interestingly, the ejections are found to be a manifestation of upwardly propagating shock waves as evidenced by the sawtooth patterns seen in the temporal-spectral plots of the Ca ii 8542 Å and H α intensities. We also found a fine-scale photospheric pattern (1″) diverging with a speed of about 2 km s{sup −1} two minutes before the plasma ejections, which seems to be a manifestation of magnetic flux emergence. As a response to the plasma ejections, the corona displayed small-scale transient brightenings. Based on our findings, we suggest that the shock waves can be excited by the local disturbance caused by magnetic reconnection between the emerging flux inside the LB and the adjacent umbral magnetic field. The disturbance generates slow-mode waves, which soon develop into shock waves, and manifest themselves as the arcsecond-scale plasma ejections. It also appears that the dissipation of mechanical energy in the shock waves can heat the local corona.

Chromospheric Plasma Ejections in a Light Bridge of a Sunspot

Science.gov (United States)

Song, Donguk; Chae, Jongchul; Yurchyshyn, Vasyl; Lim, Eun-Kyung; Cho, Kyung-Suk; Yang, Heesu; Cho, Kyuhyoun; Kwak, Hannah

2017-02-01

It is well-known that light bridges (LBs) inside a sunspot produce small-scale plasma ejections and transient brightenings in the chromosphere, but the nature and origin of such phenomena are still unclear. Utilizing the high-spatial and high-temporal resolution spectral data taken with the Fast Imaging Solar Spectrograph and the TiO 7057 Å broadband filter images installed at the 1.6 m New Solar Telescope of Big Bear Solar Observatory, we report arcsecond-scale chromospheric plasma ejections (1.″7) inside a LB. Interestingly, the ejections are found to be a manifestation of upwardly propagating shock waves as evidenced by the sawtooth patterns seen in the temporal-spectral plots of the Ca II 8542 Å and Hα intensities. We also found a fine-scale photospheric pattern (1″) diverging with a speed of about 2 km s-1 two minutes before the plasma ejections, which seems to be a manifestation of magnetic flux emergence. As a response to the plasma ejections, the corona displayed small-scale transient brightenings. Based on our findings, we suggest that the shock waves can be excited by the local disturbance caused by magnetic reconnection between the emerging flux inside the LB and the adjacent umbral magnetic field. The disturbance generates slow-mode waves, which soon develop into shock waves, and manifest themselves as the arcsecond-scale plasma ejections. It also appears that the dissipation of mechanical energy in the shock waves can heat the local corona.

Witnessing Solar Rejuvenation

Science.gov (United States)

Kohler, Susanna

2015-09-01

At the end of last year, the Suns large-scale magnetic field suddenly strengthened, reaching its highest value in over two decades. Here, Neil Sheeley and Yi-Ming Wang (both of the Naval Research Laboratory) propose an explanation for why this happened and what it predicts for the next solar cycle.Magnetic StrengtheningUntil midway through 2014, solar cycle 24 the current solar cycle was remarkably quiet. Even at its peak, it averaged only 79 sunspots per year, compared to maximums of up to 190 in recent cycles. Thus it was rather surprising when, toward the end of 2014, the Suns large-scale magnetic field underwent a sudden rejuvenation, with its mean field leaping up to its highest values since 1991 and causing unprecedentedly large numbers of coronal loops to collapse inward.Yet in spite of the increase we observed in the Suns open flux (the magnetic flux leaving the Suns atmosphere, measured from Earth), there was not a significant increase in solar activity, as indicated by sunspot number and the rate of coronal mass ejections. This means that the number of sources of magnetic flux didnt increase so Sheeley and Wang conclude that flux must instead have been emerging from those sources in a more efficient way! But how?Aligned ActivityWSO open flux and the radial component of the interplanetary magnetic field (measures of the magnetic flux leaving the Suns photosphere and heliosphere, respectively), compared to sunspot number (in units of 100 sunspots). A sudden increase in flux is visible after the peak of each of the last four sunspot cycles. Click for a larger view! [Sheeley Wang 2015]The authors show that the active regions on the solar surface in late 2014 lined up in such a way that the emerging flux was enhanced, forming a strong equatorial dipole field that accounts for the sudden rejuvenation observed.Interestingly, this rejuvenation of the Suns open flux wasnt just a one-time thing; similar bursts have occurred shortly after the peak of every sunspot

VizieR Online Data Catalog: Solar activity reconstructed for 3 millennia (Usoskin+, 2014)

Science.gov (United States)

Usoskin, I. G.; Hulot, G.; Gallet, Y.; Roth, R.; Licht, A.; Joos, F.; Kovaltsov, G. A.; Thebault, E.; Khokhlov, A.

2014-02-01

Indices of solar activity reconstructed from 14C using the m used in the paper. Two indices are provided - the sunspot number and the cosmic ray modulation potential, both with the 95% confidence intervals. The data sets are provided with decadal resolution, thus the individual solar cycles are not resolved. (2 data files).

ASSESSMENT OF HUMAN RESOURCES FOR REGIONAL INNOVATION ACTIVITY

Directory of Open Access Journals (Sweden)

R. R. Lukyanova

2010-03-01

Full Text Available The paper deals with the issues of human resource development regarding an innovation activity. Concepts of labor and human resources have been surveyed. An integral index for assessment of human resources for regional innovation activity has been developed and assessment of the Russian regions has been made on the basis of it. Development tendencies of modern human resources for innovation activity in Russia have been revealed.

MULTI-WAVELENGTH STUDY OF TRANSITION REGION PENUMBRAL SUBARCSECOND BRIGHT DOTS USING IRIS AND NST

Energy Technology Data Exchange (ETDEWEB)

Deng, Na; Liu, Chang; Xu, Yan; Wang, Haimin [Space Weather Research Laboratory, New Jersey Institute of Technology, University Heights, Newark, NJ 07102-1982 (United States); Yurchyshyn, Vasyl [Big Bear Solar Observatory, New Jersey Institute of Technology, 40386 North Shore Lane, Big Bear City, CA 92314-9672 (United States); Tian, Hui [School of Earth and Space Sciences, Peking University, Beijing, 100871 (China); Kleint, Lucia, E-mail: na.deng@njit.edu [University of Applied Sciences and Arts Northwestern Switzerland, Bahnhofstr. 6, 5210 Windisch (Switzerland)

2016-10-01

Using high-resolution transition region (TR) observations taken by the Interface Region Imaging Spectrograph ( IRIS ) mission, Tian et al. revealed numerous short-lived subarcsecond bright dots (BDs) above sunspots (mostly located in the penumbrae), which indicate yet unexplained small-scale energy releases. Moreover, whether or not these subarcsecond TR brightenings have any signature in the lower atmosphere and how they are formed are still not fully resolved. This paper presents a multi-wavelength study of the TR penumbral BDs using a coordinated observation of a near disk center sunspot with IRIS and the 1.6 m New Solar Telescope (NST) at the Big Bear Solar Observatory. NST provides high-resolution chromospheric and photospheric observations with narrowband H α imaging spectroscopy and broadband TiO images, respectively, complementary to IRIS TR observations. A total of 2692 TR penumbral BDs are identified from a 37 minute time series of IRIS 1400 Å slit-jaw images. Their locations tend to be associated more with downflowing and darker fibrils in the chromosphere, and weakly associated with bright penumbral features in the photosphere. However, temporal evolution analyses of the BDs show that there is no consistent and convincing brightening response in the chromosphere. These results are compatible with a formation mechanism of the TR penumbral BDs by falling plasma from coronal heights along more vertical and dense magnetic loops. The BDs may also be produced by small-scale impulsive magnetic reconnection taking place sufficiently high in the atmosphere that has no energy release in the chromosphere.

Solar active region display system

Science.gov (United States)

Golightly, M.; Raben, V.; Weyland, M.

2003-04-01

The Solar Active Region Display System (SARDS) is a client-server application that automatically collects a wide range of solar data and displays it in a format easy for users to assimilate and interpret. Users can rapidly identify active regions of interest or concern from color-coded indicators that visually summarize each region's size, magnetic configuration, recent growth history, and recent flare and CME production. The active region information can be overlaid onto solar maps, multiple solar images, and solar difference images in orthographic, Mercator or cylindrical equidistant projections. Near real-time graphs display the GOES soft and hard x-ray flux, flare events, and daily F10.7 value as a function of time; color-coded indicators show current trends in soft x-ray flux, flare temperature, daily F10.7 flux, and x-ray flare occurrence. Through a separate window up to 4 real-time or static graphs can simultaneously display values of KP, AP, daily F10.7 flux, GOES soft and hard x-ray flux, GOES >10 and >100 MeV proton flux, and Thule neutron monitor count rate. Climatologic displays use color-valued cells to show F10.7 and AP values as a function of Carrington/Bartel's rotation sequences - this format allows users to detect recurrent patterns in solar and geomagnetic activity as well as variations in activity levels over multiple solar cycles. Users can customize many of the display and graph features; all displays can be printed or copied to the system's clipboard for "pasting" into other applications. The system obtains and stores space weather data and images from sources such as the NOAA Space Environment Center, NOAA National Geophysical Data Center, the joint ESA/NASA SOHO spacecraft, and the Kitt Peak National Solar Observatory, and can be extended to include other data series and image sources. Data and images retrieved from the system's database are converted to XML and transported from a central server using HTTP and SOAP protocols, allowing

419-420

Indian Academy of Sciences (India)

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locations of sunspots with strong magnetic fields and at the locations of plages having larger areas. Presented here are the results of an analysis of intensity of green line emission and the active region magnetic signatures as seen in Stanford magnetograms. The data base used in this study consisted of homogeneous data ...

Twist of Magnetic Fields in Solar Active Regions Hongqi Zhang ...

Indian Academy of Sciences (India)

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in active regions also shows the butterfly pattern through the solar cycle. And, less than 30% of the active regions do not follow the general trend (Zhang & Bao 1998). The longitudinal distribution of current helicity parameter h|| of active regions in both the hemispheres in the last decade was presented by Zhang & Bao ...

Propagating Disturbances in Coronal Loops: A Detailed Analysis of Propagation Speeds

Science.gov (United States)

Kiddie, G.; De Moortel, I.; Del Zanna, G.; McIntosh, S. W.; Whittaker, I.

2012-08-01

Quasi-periodic disturbances have been observed in the outer solar atmosphere for many years. Although first interpreted as upflows (Schrijver et al., Solar Phys. 187, 261, 1999), they have been widely regarded as slow magneto-acoustic waves, due to their observed velocities and periods. However, recent observations have questioned this interpretation, as periodic disturbances in Doppler velocity, line width, and profile asymmetry were found to be in phase with the intensity oscillations (De Pontieu and McIntosh, Astrophys. J. 722, 1013, 2010; Tian, McIntosh, and De Pontieu, Astrophys. J. Lett. 727, L37, 2011), suggesting that the disturbances could be quasi-periodic upflows. Here we conduct a detailed analysis of the velocities of these disturbances across several wavelengths using the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO). We analysed 41 examples, including both sunspot and non-sunspot regions of the Sun. We found that the velocities of propagating disturbances (PDs) located at sunspots are more likely to be temperature dependent, whereas the velocities of PDs at non-sunspot locations do not show a clear temperature dependence. This suggests an interpretation in terms of slow magneto-acoustic waves in sunspots but the nature of PDs in non-sunspot (plage) regions remains unclear. We also considered on what scale the underlying driver is affecting the properties of the PDs. Finally, we found that removing the contribution due to the cooler ions in the 193 Å wavelength suggests that a substantial part of the 193 Å emission of sunspot PDs can be attributed to the cool component of 193 Å.

Some results of model calculations of the solar S-component radio emission

International Nuclear Information System (INIS)

Krueger, A.; Hildebrandt, J.

1985-01-01

Numerical calculations of special characteristics of the solar S-component microwave radiation are presented on the basis of recent sunspot and plage models. Quantitative results are discussed and can be used for the plasma diagnostics of solar active regions by comparisons with observations with high spatial and spectral resolution. The possibility of generalized applications to magnetic stars and stellar activity is briefly noted. (author)

REGIONALIZATION OF MANAGEMENT PROCESS BY INNOVATIVE ACTIVITY

Directory of Open Access Journals (Sweden)

E. V. Sibirskaia

2014-01-01

Full Text Available Summary. In current market conditions, the economy and Russia's accession to international trade scholars and experts from various fields of knowledge paying special attention to a huge set of regional problems. The growing role of regional research determines the level of establishing effective mechanisms for the implementation of the economic interests of actors as well as economic development and improving the quality of human life is the priority objectives of federal, regional and local authorities. Today, the Russian economic science faces a global goal - to develop ways and means of transformation of the Russian economy and bring it to a path of sustainable, innovative development, providing new quality of life. Achieving this goal must surely be a central task of the Russian economics and politics, as in the near future and the long term In article authors opened the maintenance of determinants of innovative development of the territory, mediated by strengthening of regionalization of management by innovative activity: condition of resource and innovative potential; the developed forms and nature of interaction between public authorities of regional level, local community and business; applied forms of integration of subjects of managing for realization of their innovative potential due to expansion of opportunities of participation in the perspective directions of scientific and technical, economic and social development; system of the incentives developing favorable conditions for introduction and development of innovative technologies, and also increases in the enterprise activity, formed by the external institutional environment; regional economic policy as instrument of increase of efficiency of innovative activity.

Relative phase asynchrony and long-range correlation of long-term solar magnetic activity

Science.gov (United States)

Deng, Linhua

2017-07-01

Statistical signal processing is one of the most important tasks in a large amount of areas of scientific studies, such as astrophysics, geophysics, and space physics. Phase recurrence analysis and long-range persistence are the two dynamical structures of the underlying processes for the given natural phenomenon. Linear and nonlinear time series analysis approaches (cross-correlation analysis, cross-recurrence plot, wavelet coherent transform, and Hurst analysis) are combined to investigate the relative phase interconnection and long-range correlation between solar activity and geomagnetic activity for the time interval from 1932 January to 2017 January. The following prominent results are found: (1) geomagnetic activity lags behind sunspot numbers with a phase shift of 21 months, and they have a high level of asynchronous behavior; (2) their relative phase interconnections are in phase for the periodic scales during 8-16 years, but have a mixing behavior for the periodic belts below 8 years; (3) both sunspot numbers and geomagnetic activity can not be regarded as a stochastic phenomenon because their dynamical behaviors display a long-term correlation and a fractal nature. We believe that the presented conclusions could provide further information on understanding the dynamical coupling of solar dynamo process with geomagnetic activity variation, and the crucial role of solar and geomagnetic activity in the long-term climate change.

ON THE NON-KOLMOGOROV NATURE OF FLARE-PRODUCTIVE SOLAR ACTIVE REGIONS

Energy Technology Data Exchange (ETDEWEB)

Mandage, Revati S. [Physics and Astronomy Department, Rice University, 6100 Main MS-61, Houston, TX 77005-1827 (United States); McAteer, R. T. James, E-mail: mcateer@nmsu.edu [Department of Astronomy, New Mexico State University, MSC 4500, Las Cruces, NM 88001 (United States)

2016-12-20

A magnetic power spectral analysis is performed on 53 solar active regions, observed from 2011 August to 2012 July. Magnetic field data obtained from the Helioseismic and Magnetic Imager, inverted as Active Region Patches, are used to study the evolution of the magnetic power index as each region rotates across the solar disk. Active regions are classified based on the numbers and sizes of solar flares they produce in order to study the relationship between flare productivity and the magnetic power index. The choice of window size and inertial range plays a key role in determining the correct magnetic power index. The overall distribution of magnetic power indices has a range of 1.0–2.5. Flare-quiet regions peak at a value of 1.6. However, flare-productive regions peak at a value of 2.2. Overall, the histogram of the distribution of power indices of flare-productive active regions is well separated from flare-quiet active regions. Only 12% of flare-quiet regions exhibit an index greater than 2, whereas 90% of flare-productive regions exhibit an index greater than 2. Flare-quiet regions exhibit a high temporal variance (i.e., the index fluctuates between high and low values), whereas flare-productive regions maintain an index greater than 2 for several days. This shows the importance of including the temporal evolution of active regions in flare prediction studies, and highlights the potential of a 2–3 day prediction window for space weather applications.

Active Pesticide Production Points, Region 9, 2013, US EPA Region 9

Data.gov (United States)

U.S. Environmental Protection Agency — This data layer represents Active Pesticide Producing Establishments in USEPA Region 9 (AZ, CA, HI and NV) that reported production for the year 2013. Pesticide...

RCA activities in the Asian and Pacific Region

International Nuclear Information System (INIS)

Kobayashi, M.

1984-01-01

So-called ''RCA'' activities - practical work undertaken within the framework of a Regional Co-operative Agreement for Research, Development and Training related to Nuclear Science and Technology for the Asian and Pacific region - are widely regarded as an example of successful co-operative effort in the application of nuclear techniques at a regional level. Activities undertaken to promote the transfer of nuclear technology within the framework of the RCA cover a large spectrum of nuclear applications in agriculture and food production, medicine, study of the environment, industry, and physics. Fourteen projects are operational this year (1984)

Activation of different cerebral functional regions following ...

African Journals Online (AJOL)

Background: To explore the brain function regions characteristics of the acupoint combination, this study observed activity changes in the brain regions of healthy volunteers after acupuncture at both Taixi (KI3) and Taichong (LR3) (KI3 + LR3) and KI3 alone using resting-state functional magnetic resonance imaging(fMRI).

Active Ageing Level of Older Persons: Regional Comparison in Thailand

Directory of Open Access Journals (Sweden)

Md. Nuruzzaman Haque

2016-01-01

Full Text Available Active ageing level and its discrepancy in different regions (Bangkok, Central, North, Northeast, and South of Thailand have been examined for prioritizing the policy agenda to be implemented. Attempt has been made to test preliminary active ageing models for Thai older persons and hence active ageing index (AAI, ranges from 0 to 1 has been estimated. Using nationally representative data and confirmatory factor analysis approach, this study justified active ageing models for female and male older persons in Thailand. Results revealed that active ageing level of Thai older persons is not high (mean AAIs for female and male older persons are 0.64 and 0.61, resp., and those are significantly different (p<0.001. Mean AAI in Central region is lower than North, Northeast, and South regions but there is no significant difference in the latter three regions of Thailand. Special emphasis should be given to Central region and policy should be undertaken for increasing active ageing level. Implementation of an Integrated Active Ageing Package (IAAP, containing policies for older persons to improve their health and economic security, to promote participation in social groups and longer working lives, and to arrange learning programs, would be helpful for increasing older persons’ active ageing level in Thailand.

The Photospheric Flow near the Flare Locations of Active Regions

Indian Academy of Sciences (India)

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in the active regions along with few locations of upflows. The localised upflows are observed in the light bridges and emerging flux regions with different speeds (Beckers & Schroter 1969). The flow patterns of flare locations in the active regions are observed by using the tower vector magnetograph (TVM) of Marshall.

Changes in measured vector magnetic fields when transformed into heliographic coordinates

Science.gov (United States)

Hagyard, M. J.

1987-01-01

The changes that occur in measured magnetic fields when they are transformed into a heliographic coordinate system are investigated. To carry out this investigation, measurements of the vector magnetic field of an active region that was observed at 1/3 the solar radius from disk center are taken, and the observed field is transformed into heliographic coordinates. Differences in the calculated potential field that occur when the heliographic normal component of the field is used as the boundary condition rather than the observed line-of-sight component are also examined. The results of this analysis show: (1) that the observed fields of sunspots more closely resemble the generally accepted picture of the distribution of umbral fields if they are displayed in heliographic coordinates; (2) that the differences in the potential calculations are less than 200 G in field strength and 20 deg in field azimuth outside sunspots; and (3) that differences in the two potential calculations in the sunspot areas are no more than 400 G in field strength but range from 60 to 80 deg in field azimuth in localized umbral areas.

Resonant behaviour of MHD waves on magnetic flux tubes. I - Connection formulae at the resonant surfaces. II - Absorption of sound waves by sunspots

Science.gov (United States)

Sakurai, Takashi; Goossens, Marcel; Hollweg, Joseph V.

1991-01-01

The present method of addressing the resonance problems that emerge in such MHD phenomena as the resonant absorption of waves at the Alfven resonance point avoids solving the fourth-order differential equation of dissipative MHD by recourse to connection formulae across the dissipation layer. In the second part of this investigation, the absorption of solar 5-min oscillations by sunspots is interpreted as the resonant absorption of sounds by a magnetic cylinder. The absorption coefficient is interpreted (1) analytically, under certain simplifying assumptions, and numerically, under more general conditions. The observed absorption coefficient magnitude is explained over suitable parameter ranges.

Diagnostics of Coronal Heating in Solar Active Regions

Science.gov (United States)

Fludra, Andrzej; Hornsey, Christopher; Nakariakov, Valery

2015-04-01

We aim to develop a diagnostic method for the coronal heating mechanism in active region loops. Observational constraints on coronal heating models have been sought using measurements in the X-ray and EUV wavelengths. Statistical analysis, using EUV emission from many active regions, was done by Fludra and Ireland (2008) who studied power-law relationships between active region integrated magnetic flux and emission line intensities. A subsequent study by Fludra and Warren (2010) for the first time compared fully resolved images in an EUV spectral line of OV 63.0 nm with the photospheric magnetic field, leading to the identification of a dominant, ubiquitous variable component of the transition region EUV emission and a discovery of a steady basal heating, and deriving the dependence of the basal heating rate on the photospheric magnetic flux density. In this study, we compare models of single coronal loops with EUV observations. We assess to what degree observations of individual coronal loops made in the EUV range are capable of providing constraints on the heating mechanism. We model the coronal magnetic field in an active region using an NLFF extrapolation code applied to a photospheric vector magnetogram from SDO/HMI and select several loops that match an SDO/AIA 171 image of the same active region. We then model the plasma in these loops using a 1D hydrostatic code capable of applying an arbitrary heating rate as a function of magnetic field strength along the loop. From the plasma parameters derived from this model, we calculate the EUV emission along the loop in AIA 171 and 335 bands, and in pure spectral lines of Fe IX 17.1 nm and Fe XVI 33.5 nm. We use different spatial distributions of the heating function: concentrated near the loop top, uniform and concentrated near the footpoints, and investigate their effect on the modelled EUV intensities. We find a diagnostics based on the dependence of the total loop intensity on the shape of the heating function

SOLAR CYCLE PROPAGATION, MEMORY, AND PREDICTION: INSIGHTS FROM A CENTURY OF MAGNETIC PROXIES

International Nuclear Information System (INIS)

Muñoz-Jaramillo, Andrés; DeLuca, Edward E.; Dasi-Espuig, María; Balmaceda, Laura A.

2013-01-01

The solar cycle and its associated magnetic activity are the main drivers behind changes in the interplanetary environment and Earth's upper atmosphere (commonly referred to as space weather). These changes have a direct impact on the lifetime of space-based assets and can create hazards to astronauts in space. In recent years there has been an effort to develop accurate solar cycle predictions (with aims at predicting the long-term evolution of space weather), leading to nearly a hundred widely spread predictions for the amplitude of solar cycle 24. A major contributor to the disagreement is the lack of direct long-term databases covering different components of the solar magnetic field (toroidal versus poloidal). Here, we use sunspot area and polar faculae measurements spanning a full century (as our toroidal and poloidal field proxies) to study solar cycle propagation, memory, and prediction. Our results substantiate predictions based on the polar magnetic fields, whereas we find sunspot area to be uncorrelated with cycle amplitude unless multiplied by area-weighted average tilt. This suggests that the joint assimilation of tilt and sunspot area is a better choice (with aims to cycle prediction) than sunspot area alone, and adds to the evidence in favor of active region emergence and decay as the main mechanism of poloidal field generation (i.e., the Babcock-Leighton mechanism). Finally, by looking at the correlation between our poloidal and toroidal proxies across multiple cycles, we find solar cycle memory to be limited to only one cycle.

SOLAR CYCLE PROPAGATION, MEMORY, AND PREDICTION: INSIGHTS FROM A CENTURY OF MAGNETIC PROXIES

Energy Technology Data Exchange (ETDEWEB)

Munoz-Jaramillo, Andres; DeLuca, Edward E. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Dasi-Espuig, Maria [Max-Planck-Institut fuer Sonnensystemforschung, D-37191 Katlenburg-Lindau (Germany); Balmaceda, Laura A., E-mail: amunoz@cfa.harvard.edu, E-mail: edeluca@cfa.harvard.edu, E-mail: dasi@mps.mpg.de, E-mail: lbalmaceda@icate-conicet.gob.ar [Institute for Astronomical, Terrestrial and Space Sciences (ICATE-CONICET), San Juan (Argentina)

2013-04-20

The solar cycle and its associated magnetic activity are the main drivers behind changes in the interplanetary environment and Earth's upper atmosphere (commonly referred to as space weather). These changes have a direct impact on the lifetime of space-based assets and can create hazards to astronauts in space. In recent years there has been an effort to develop accurate solar cycle predictions (with aims at predicting the long-term evolution of space weather), leading to nearly a hundred widely spread predictions for the amplitude of solar cycle 24. A major contributor to the disagreement is the lack of direct long-term databases covering different components of the solar magnetic field (toroidal versus poloidal). Here, we use sunspot area and polar faculae measurements spanning a full century (as our toroidal and poloidal field proxies) to study solar cycle propagation, memory, and prediction. Our results substantiate predictions based on the polar magnetic fields, whereas we find sunspot area to be uncorrelated with cycle amplitude unless multiplied by area-weighted average tilt. This suggests that the joint assimilation of tilt and sunspot area is a better choice (with aims to cycle prediction) than sunspot area alone, and adds to the evidence in favor of active region emergence and decay as the main mechanism of poloidal field generation (i.e., the Babcock-Leighton mechanism). Finally, by looking at the correlation between our poloidal and toroidal proxies across multiple cycles, we find solar cycle memory to be limited to only one cycle.

Sports participation, physical activity, and health in the European regions.

Science.gov (United States)

Lera-López, Fernando; Marco, Rocio

2018-08-01

In a context of stagnation of the level of health-enhancing physical activity in Europe, this study examines the geographical stratification of sports participation and physical activity (PA) at the regional level in 28 European countries. While previous research has focused on the national approach, this study considers the regional level across 208 European regions. Individual survey data from the Eurobarometer 80.2 is combined with a regional-level approach to the 208 regions to quantify sports participation and PA at the regional level. The results show important differences and a geographical stratification of sports participation and PA among the European regions, albeit following different patterns. In particular, a north-south gap is identified in terms of PA rates and an east-west gap is detected in terms of sports participation levels. Applying the cluster technique, a taxonomy of four different European regions is developed considering both types of indicators. Finally, the existence of sports spatial spillovers among regions is verified, obtaining a positive autocorrelation among neighbouring regions for being involved in PA and sporting activities. The results may have significant implications in terms of policy measures to improve health through PA and sports participation at the regional level in Europe.

Towards understanding the nature of any relationship between Solar Activity and Cosmic Rays with thunderstorm activity and lightning discharge

Science.gov (United States)

O'Regan, J.; Muller, J.-P.; Matthews, S.

2012-04-01

The runaway breakdown hypothesis of lightning discharge has predicted relationships between cosmic rays' interactions with the atmosphere and thunderstorm production and lightning activity. Precipitating energetic particles lead to the injection of MeV-energy electrons into electrified thunderclouds [1,2], resulting in runaway breakdown occurring, and assisting in the process of charge separation [2]. Previous lightning studies show that correlations to solar activity are weak but significant, with better correlations to solar activity and cosmic rays when carried out over smaller geographical areas [3,4,5,6] and over longer timescales [6]. In this work, correlations are explored between variations of SEPs and lightning activity levels at various spatio-temporal scales. Temporal scales span from short-term (days) scales surrounding large Earth-directed coronal mass ejection (CME) events to long-term (years) scales. Similarly, spatial scales span from 1-degree x 1-degree latitudinal-longitudinal grid scales to an entirely global study, for varying timescales. Additionally, investigation of correlation sign and statistical significance by 1-degree latitudinal bands is also employed, allowing a comparative study of lightning activity relative to regions of greatest - and contrasting regions of relative absence of - energetic particle precipitation. These regions are determined from electron and proton flux maps, derived from measurements from the Medium Energy Proton and Electron Detector (MEPED) onboard the Polar Orbiting Environmental Satellite (POES) system. Lightning data is obtained from the World Wide Lightning Location Network (WWLLN) for the period 2005 to 2011. The correlations of lightning strike rates are carried out with respect to Relative Sunspot Number (R), 10.7cm Solar radio flux (F10.7), Galactic Cosmic Ray (GCR) neutron monitor flux, the Ap geomagnetic activity index, and Disturbance Storm Time (DST) index. Correlations show dramatic variations in

Results from Kodaikanal Synoptic Observations

Indian Academy of Sciences (India)

tribpo

the global solar activity, the first component being the well known sunspot activity and the butterfly diagram. These two components occur at different latitude belts each lasting for about 11 years but with a phase difference of 5-6 years, the polar faculae leading the sunspot activity (see Fig. 2). This gives rise to the concept of ...

Multi-wavelength Observations of Solar Acoustic Waves Near Active Regions

Science.gov (United States)

Monsue, Teresa; Pesnell, Dean; Hill, Frank

2018-01-01

Active region areas on the Sun are abundant with a variety of waves that are both acoustically helioseismic and magnetohydrodynamic in nature. The occurrence of a solar flare can disrupt these waves, through MHD mode-mixing or scattering by the excitation of these waves. We take a multi-wavelength observational approach to understand the source of theses waves by studying active regions where flaring activity occurs. Our approach is to search for signals within a time series of images using a Fast Fourier Transform (FFT) algorithm, by producing multi-frequency power map movies. We study active regions both spatially and temporally and correlate this method over multiple wavelengths using data from NASA’s Solar Dynamics Observatory. By surveying the active regions on multiple wavelengths we are able to observe the behavior of these waves within the Solar atmosphere, from the photosphere up through the corona. We are able to detect enhancements of power around active regions, which could be acoustic power halos and of an MHD-wave propagating outward by the flaring event. We are in the initial stages of this study understanding the behaviors of these waves and could one day contribute to understanding the mechanism responsible for their formation; that has not yet been explained.

The origin of two X-class flares in active region NOAA 12673. Shear flows and head-on collision of new and preexisting flux

Science.gov (United States)

Verma, Meetu

2018-05-01

Flare-prolific active region NOAA 12673 produced consecutive X2.2 and X9.3 flares on the 6 September 2017. To scrutinize the morphological, magnetic, and horizontal flow properties associated with these flares, a seven-hour time series was used consisting of continuum images, line-of-sight and vector magnetograms, and 1600 Å UV images. These data were acquired with the Helioseismic and Magnetic Imager (HMI) and the Atmospheric Imaging Assembly (AIA). The white-light flare emission differed for both flares, while the X2.2 flare displayed localized, confined flare kernels, the X9.3 flare exhibited a two-ribbon structure. In contrast, the excess UV emission exhibited a similar structure for both flares, but with larger areal extent for the X9.3 flare. These two flares represented a scenario in which the first confined flare acted as precursor, setting up the stage for the more extended flare. Difference maps for continuum and magnetograms revealed locations of significant changes, that is, penumbral decay and umbral strengthening. The curved magnetic polarity inversion line in the δ-spot was the fulcrum of most changes. Horizontal proper motions were computed using the differential affine velocity estimator for vector magnetograms (DAVE4VM). Persistent flow features included (1) strong shear flows along the polarity inversion line, where the negative, parasitic polarity tried to bypass the majority, positive-polarity part of the δ-spot in the north, (2) a group of positive-polarity spots, which moved around the δ-spot in the south, moving away from the δ-spot with significant horizontal flow speeds, and (3) intense moat flows partially surrounding the penumbra of several sunspots, which became weaker in regions with penumbral decay. The enhanced flare activity has its origin in the head-on collision of newly emerging flux with an already existing regular, α-spot. Umbral cores of emerging bipoles were incorporated in its penumbra, creating a δ-configuration with

The THMIS-MTR observation of a active region filament

Science.gov (United States)

Zong, W. G.; Tang, Y. H.; Fang, C.

We present some THMIS-MTR observations of a active region filament on September 4, 2002. The full stokes parameters of the filament were obtained in Hα, CaII 8542 and FeI 6302. By use of the data with high spatial resolution(0.44" per pixel), we probed the fine structure of the filament and gave out the parameters at the barbs' endpoints, including intensity, velocity and longitudinal magnetic field. Comparing the quiescent filament which we have discussed before, we find that: 1)The velocities of the barbs' endpoints are much bigger in the active region filament, the values are more than one thousand meters per second. 2)The barbs' endpoints terminate at the low logitudinal magnetic field in the active region filament, too.

Thoughts on the development of active regional public health systems.

Science.gov (United States)

Reis, Ademar Arthur Chioro Dos; Sóter, Ana Paula Menezes; Furtado, Lumena Almeida Castro; Pereira, Silvana Souza da Silva

2017-04-01

Decentralization and regionalization are strategic themes for reforms in the health system. This paper analyzes the complex process of health regionalization being developed in Brazil. This paper identifies that the normative framework from the Brazilian National Health System, SUS has made advances with respect to its institutionalization and overcoming the initial centrality involved in municipalization. This has strengthened the development of regionalization and the intergovernmental agreement on health but the evidence points to the need to promote a revision. Based on document analysis, literature review and the views given by the authors involved in management in SUS as well as generating radically different views, the challenges for the construction of a regionalization that is active, is debated. We also discuss: its relations with planning and the dimensioning of service networks, the production of active care networks and shared management spaces, the inter-federative agreements and regional regulations, the capacity to coordinate regional systems and financing and the impact of the political dimension and electoral cycles. Regionalization (and SUS itself) is an open book, therefore ways and possibilities on how to maintain an active form of regionalization can be recommended.

Unwinding motion of a twisted active region filament

Energy Technology Data Exchange (ETDEWEB)

Yan, X. L.; Xue, Z. K.; Kong, D. F. [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China); Liu, J. H. [Department of Physics, Shijiazhuang University, Shijiazhuang 050035 (China); Xu, C. L. [Yunnan Normal University, Kunming 650092 (China)

2014-12-10

To better understand the structures of active region filaments and the eruption process, we study an active region filament eruption in active region NOAA 11082 in detail on 2010 June 22. Before the filament eruption, the opposite unidirectional material flows appeared in succession along the spine of the filament. The rising of the filament triggered two B-class flares at the upper part of the filament. As the bright material was injected into the filament from the sites of the flares, the filament exhibited a rapid uplift accompanying the counterclockwise rotation of the filament body. From the expansion of the filament, we can see that the filament consisted of twisted magnetic field lines. The total twist of the filament is at least 5π obtained by using a time slice method. According to the morphology change during the filament eruption, it is found that the active region filament was a twisted flux rope and its unwinding motion was like a solar tornado. We also find that there was a continuous magnetic helicity injection before and during the filament eruption. It is confirmed that magnetic helicity can be transferred from the photosphere to the filament. Using the extrapolated potential fields, the average decay index of the background magnetic fields over the filament is 0.91. Consequently, these findings imply that the mechanism of solar filament eruption could be due to the kink instability and magnetic helicity accumulation.

Determinants of Foreign Technological Activity in German Regions

DEFF Research Database (Denmark)

Dettmann, Eva; Lacasa, Iciar Dominguez; Günther, Jutta

This paper analyses the determinants of spatial distribution of foreign technological activity across 96 German regions (1996-2009). We identify foreign inventive activity by applying the ‘cross-border-ownership concept’ to transnational patent applications. The descriptive analysis shows...

Regional and national radiation protection activities in Egypt

International Nuclear Information System (INIS)

Gomaa, M.A.M.

2008-01-01

Radiation protection activities in Egypt go back to 1957 where the Egyptian Atomic Energy Commission (EAEC) Law was issued. Radiation protection and civil defense department was one of EAEC eighth departments. Ionizing radiation law was issued in 1960 and its executive regulation in 1962. The main aim of the present work is to through some light on the current radiation protection activities in Egypt. This includes not only the role of governmental organizations but also to the non governmental organizations. Currently a new Nuclear Safety law is understudy. Regional activities such as holding the second all African IRPA regional radiation protection congress which was held in April 2007 and national training and workshops are held regularly through EAEA, AAEA and MERRCAC. (author)

EUV and Magnetic Activities Associated with Type-I Solar Radio Bursts

Science.gov (United States)

Li, C. Y.; Chen, Y.; Wang, B.; Ruan, G. P.; Feng, S. W.; Du, G. H.; Kong, X. L.

2017-06-01

Type-I bursts ( i.e. noise storms) are the earliest-known type of solar radio emission at the meter wavelength. They are believed to be excited by non-thermal energetic electrons accelerated in the corona. The underlying dynamic process and exact emission mechanism still remain unresolved. Here, with a combined analysis of extreme ultraviolet (EUV), radio and photospheric magnetic field data of unprecedented quality recorded during a type-I storm on 30 July 2011, we identify a good correlation between the radio bursts and the co-spatial EUV and magnetic activities. The EUV activities manifest themselves as three major brightening stripes above a region adjacent to a compact sunspot, while the magnetic field there presents multiple moving magnetic features (MMFs) with persistent coalescence or cancelation and a morphologically similar three-part distribution. We find that the type-I intensities are correlated with those of the EUV emissions at various wavelengths with a correlation coefficient of 0.7 - 0.8. In addition, in the region between the brightening EUV stripes and the radio sources there appear consistent dynamic motions with a series of bi-directional flows, suggesting ongoing small-scale reconnection there. Mainly based on the induced connection between the magnetic motion at the photosphere and the EUV and radio activities in the corona, we suggest that the observed type-I noise storms and the EUV brightening activities are the consequence of small-scale magnetic reconnection driven by MMFs. This is in support of the original proposal made by Bentley et al. ( Solar Phys. 193, 227, 2000).

Principal components and iterative regression analysis of geophysical series: Application to Sunspot number (1750 2004)

Science.gov (United States)

Nordemann, D. J. R.; Rigozo, N. R.; de Souza Echer, M. P.; Echer, E.

2008-11-01

We present here an implementation of a least squares iterative regression method applied to the sine functions embedded in the principal components extracted from geophysical time series. This method seems to represent a useful improvement for the non-stationary time series periodicity quantitative analysis. The principal components determination followed by the least squares iterative regression method was implemented in an algorithm written in the Scilab (2006) language. The main result of the method is to obtain the set of sine functions embedded in the series analyzed in decreasing order of significance, from the most important ones, likely to represent the physical processes involved in the generation of the series, to the less important ones that represent noise components. Taking into account the need of a deeper knowledge of the Sun's past history and its implication to global climate change, the method was applied to the Sunspot Number series (1750-2004). With the threshold and parameter values used here, the application of the method leads to a total of 441 explicit sine functions, among which 65 were considered as being significant and were used for a reconstruction that gave a normalized mean squared error of 0.146.

Asia Section. Regional Activities Division. Paper.

Science.gov (United States)

International Federation of Library Associations, The Hague (Netherlands).

Two papers on library and information activities in developing nations, particularly in India and other Asian countries, were presented at the 1983 International Federation of Library Associations (IFLA) conference. In "IFLA in Asia: A Review of the Work of the Regional Section for Asia," Edward Lim Huck Tee (Malaysia) describes the low…

Recurrent activity in higher order, modality non-specific brain regions

DEFF Research Database (Denmark)

Lou, Hans Olav Christensen; Joensson, Morten; Biermann-Ruben, Katja

2011-01-01

It has been proposed that the workings of the brain are mainly intrinsically generated recurrent neuronal activity, with sensory inputs as modifiers of such activity in both sensory and higher order modality non-specific regions. This is supported by the demonstration of recurrent neuronal activity...... in the visual system as a response to visual stimulation. In contrast recurrent activity has never been demonstrated before in higher order modality non-specific regions. Using magneto-encephalography and Granger causality analysis, we tested in a paralimbic network the hypothesis that stimulation may enhance...... causal recurrent interaction between higher-order, modality non-specific regions. The network includes anterior cingulate/medial prefrontal and posterior cingulate/medial parietal cortices together with pulvinar thalami, a network known to be effective in autobiographic memory retrieval and self...

A Hot Downflowing Model Atmosphere for Umbral Flashes and the Physical Properties of Their Dark Fibrils

Energy Technology Data Exchange (ETDEWEB)

Henriques, V. M. J.; Mathioudakis, M. [Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, BT7 1NN, Northern Ireland (United Kingdom); Socas-Navarro, H. [Instituto de Astrofísica de Canarias, Avda vía Láctea S/N, E-38205 La Laguna, Tenerife (Spain); Rodríguez, J. de la Cruz, E-mail: v.henriques@qub.ac.uk [Institute for Solar Physics, Department of Astronomy, Stockholm University, AlbaNova University Centre, SE-106 91 Stockholm (Sweden)

2017-08-20

We perform non-LTE inversions in a large set of umbral flashes, including the dark fibrils visible within them, and in the quiescent umbra by using the inversion code NICOLE on a set of full Stokes high-resolution Ca ii λ 8542 observations of a sunspot at disk center. We find that the dark structures have Stokes profiles that are distinct from those of the quiescent and flashed regions. They are best reproduced by atmospheres that are more similar to the flashed atmosphere in terms of velocities, even if with reduced amplitudes. We also find two sets of solutions that finely fit the flashed profiles: a set that is upflowing, featuring a transition region that is deeper than in the quiescent case and preceded by a slight dip in temperature, and a second solution with a hotter atmosphere in the chromosphere but featuring downflows close to the speed of sound at such heights. Such downflows may be related, or even dependent, on the presence of coronal loops, rooted in the umbra of sunspots, as is the case in the region analyzed. Similar loops have been recently observed to have supersonic downflows in the transition region and are consistent with the earlier “sunspot plumes,” which were invariably found to display strong downflows in sunspots. Finally, we find, on average, a magnetic field reduction in the flashed areas, suggesting that the shock pressure is moving field lines in the upper layers.

Exoplanet Transits of Stellar Active Regions

Science.gov (United States)

Giampapa, Mark S.; Andretta, Vincenzo; Covino, Elvira; Reiners, Ansgar; Esposito, Massimiliano

2018-01-01

We report preliminary results of a program to obtain high spectral- and temporal-resolution observations of the neutral helium triplet line at 1083.0 nm in transiting exoplanet systems. The principal objective of our program is to gain insight on the properties of active regions, analogous to solar plages, on late-type dwarfs by essentially using exoplanet transits as high spatial resolution probes of the stellar surface within the transit chord. The 1083 nm helium line is a particularly appropriate diagnostic of magnetized areas since it is weak in the quiet photosphere of solar-type stars but appears strongly in absorption in active regions. Therefore, during an exoplanet transit over the stellar surface, variations in its absorption equivalent width can arise that are functions of the intrinsic strength of the feature in the active region and the known relative size of the exoplanet. We utilized the Galileo Telescope and the GIANO-B near-IR echelle spectrograph to obtain 1083 nm spectra during transits in bright, well-known systems that include HD 189733, HD 209458, and HD 147506 (HAT-P-2). We also obtained simultaneous auxiliary data on the same telescope with the HARPS-N UV-Visible echelle spectrograph. We will present preliminary results from our analysis of the observed variability of the strength of the He I 1083 nm line during transits.Acknowledgements: Based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Fundación Galileo Galilei of the INAF (Istituto Nazionale di Astrofisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. The NSO is operated by AURA under a cooperative agreement with the NSF.

Extreme Trust Region Policy Optimization for Active Object Recognition.

Science.gov (United States)

Liu, Huaping; Wu, Yupei; Sun, Fuchun; Huaping Liu; Yupei Wu; Fuchun Sun; Sun, Fuchun; Liu, Huaping; Wu, Yupei

2018-06-01

In this brief, we develop a deep reinforcement learning method to actively recognize objects by choosing a sequence of actions for an active camera that helps to discriminate between the objects. The method is realized using trust region policy optimization, in which the policy is realized by an extreme learning machine and, therefore, leads to efficient optimization algorithm. The experimental results on the publicly available data set show the advantages of the developed extreme trust region optimization method.

Birth and development of active region and chromospheric network

Energy Technology Data Exchange (ETDEWEB)

Kartashova, L G

1975-01-01

Formation and development of 15 active regions of a simple bipolar configuration with small-sized spots and without noticeable penumbras have been studied by the data of observations with a coronograph CA n the centre and wings of the Hsub(a) line. Resolution on the photographs is 2''. The following conclusions have been drawn: first bright details of the active region formed are generated through brightening of bright points of the chromosphere grid; intensification and stretching of dark points of the chromosphere grid results in the formation of fibrous structure in the vicinity of active region; spots appear either between the flocculi points, or near them closer to the centre of the corresponding cell of the chromosphere grid, among dark points of the chromosphere grid no spots are usually formed; in the process of growing of a simple bipolar group the leader and tail spots draw apart together with the chromosphere grid cells, in which they are formed; at the stage of fast growth in the neighbourhood of most large of the groups under studies a formation of arcs or of almost closed contours of the chromosphere grid is observed in the wings of the line. This rearrangement of the chromosphere grid is apparently closely connected with the formation of a fibrous structure around the active region.

Distribution of activity at the solar active longitudes between 1979 - 2011 in the northern hemisphere

Science.gov (United States)

Gyenge, N.; Baranyi, T.; Ludmány, A.

The solar active longitudes were studied in the northern hemisphere in cycles 22 and 23 by using data of DPD sunspot catalogue. The active longitudes are not fixed in the Carrington system, they have a well recognizable migration path between the descending phase of cycle 21 (from about 1984) and ascending phase of cycle 23 (until about 1996), out of this interval the migration path is ambiguous. The longitudinal distribution on both sides of the path has been computed and averaged for the length of the path. The so-called flip-flop phenomenon, when the activity temporarily gets to the opposite longitude, can also be recognized. The widths of the active domains are fairly narrow in the increasing and decaying phases of cycle 22, their half widths are about 20°-30° for both the main and secondary active belts but it is more flat and stretched around the maximum with a half width of about 60°.

Cooling Active Region Loops Observed With SXT and TRACE

OpenAIRE

Winebarger, Amy R.; Warren, Harry P.

2005-01-01

An Impulsive Heating Multiple Strand (IHMS) Model is able to reproduce the observational characteristics of EUV (~ 1 MK) active region loops. This model implies that some of the loops must reach temperatures where X-ray filters are sensitive (> 2.5 MK) before they cool to EUV temperatures. Hence, some bright EUV loops must be preceded by bright X-ray loops. Previous analysis of X-ray and EUV active region observations, however, have concluded that EUV loops are not preceded by X-ray loops. In...

Predictions of Solar Cycle 24: How are We Doing?

Science.gov (United States)

Pesnell, William D.

2016-01-01

Predictions of solar activity are an essential part of our Space Weather forecast capability. Users are requiring usable predictions of an upcoming solar cycle to be delivered several years before solar minimum. A set of predictions of the amplitude of Solar Cycle 24 accumulated in 2008 ranged from zero to unprecedented levels of solar activity. The predictions formed an almost normal distribution, centered on the average amplitude of all preceding solar cycles. The average of the current compilation of 105 predictions of the annual-average sunspot number is 106 +/- 31, slightly lower than earlier compilations but still with a wide distribution. Solar Cycle 24 is on track to have a below-average amplitude, peaking at an annual sunspot number of about 80. Our need for solar activity predictions and our desire for those predictions to be made ever earlier in the preceding solar cycle will be discussed. Solar Cycle 24 has been a below-average sunspot cycle. There were peaks in the daily and monthly averaged sunspot number in the Northern Hemisphere in 2011 and in the Southern Hemisphere in 2014. With the rapid increase in solar data and capability of numerical models of the solar convection zone we are developing the ability to forecast the level of the next sunspot cycle. But predictions based only on the statistics of the sunspot number are not adequate for predicting the next solar maximum. I will describe how we did in predicting the amplitude of Solar Cycle 24 and describe how solar polar field predictions could be made more accurate in the future.

Activization of the state policy on euro-regional cooperation in the sphere of the interstate regional governance

Directory of Open Access Journals (Sweden)

V. I. Pak

2016-09-01

Research objective is the justification of the need of activization of the state policy on Euro-regional cooperation in the sphere of the interstate regional governance. During the research it is recognized that the realization of the state policy on the basis of the considered principles, tools, functions, factors and methods has to execute a main objective of the interstate regional control which is exercised in the sphere of Euro-regional cooperation and to promote adjustment of close mutually beneficial relations of Ukraine and neighboring states, to increase competitiveness of the Ukrainian territories and the most effective use of capacity of the Ukrainian regions in the course of activity of Euro-regions. Finally, such state policy has to be focused on the maintenance of the sufficient standard of living of the population, on ensuring integrity and unity of the social and economic space of the country, on formation of the conditions of sustainable and industrial and innovative development of regions, which will provide its harmonious integration into the European environment.

Geometry of Hα active region loops observed on the solar disk

International Nuclear Information System (INIS)

Chuan-le, C.; Loughhead, R.E.

1983-01-01

Plasma loops are the dominant structures in the higher levels of the Sun's atmosphere above active regions. A geometrical technique has been used to reconstruct the true shapes of two large dark loops of the type ordinarily found in active regions in the absence of flares

Waste production and regional growth of marine activities an econometric model.

Science.gov (United States)

Bramati, Maria Caterina

2016-11-15

Coastal regions are characterized by intense human activity and climatic pressures, often intensified by competing interests in the use of marine waters. To assess the effect of public spending on the regional economy, an econometric model is here proposed. Not only are the regional investment and the climatic risks included in the model, but also variables related to the anthropogenic pressure, such as population, economic activities and waste production. Feedback effects of economic and demographic expansion on the pollution of coastal areas are also considered. It is found that dangerous waste increases with growing shipping and transportation activities and with growing population density in non-touristic coastal areas. On the other hand, the amount of non-dangerous wastes increases with marine mining, defense and offshore energy production activities. However, lower waste production occurs in areas where aquaculture and touristic industry are more exploited, and accompanied by increasing regional investment in waste disposal. Copyright © 2016 Elsevier Ltd. All rights reserved.

Variations and Regularities in the Hemispheric Distributions in Sunspot Groups of Various Classes

Science.gov (United States)

Gao, Peng-Xin

2018-05-01

The present study investigates the variations and regularities in the distributions in sunspot groups (SGs) of various classes in the northern and southern hemispheres from Solar Cycles (SCs) 12 to 23. Here, we use the separation scheme that was introduced by Gao, Li, and Li ( Solar Phys. 292, 124, 2017), which is based on A/U ( A is the corrected area of the SG, and U is the corrected umbral area of the SG), in order to separate SGs into simple SGs (A/U ≤ 4.5) and complex SGs (A/U > 6.2). The time series of Greenwich photoheliographic results from 1875 to 1976 (corresponding to complete SCs 12 - 20) and Debrecen photoheliographic data during the period 1974 - 2015 (corresponding to complete SCs 21 - 23) are used to show the distributions of simple and complex SGs in the northern and southern hemispheres. The main results we obtain are reported as follows: i) the larger of the maximum annual simple SG numbers in the two hemispheres and the larger of the maximum annual complex SG numbers in the two hemispheres occur in different hemispheres during SCs 12, 14, 18, and 19; ii) the relative changing trends of two curves - cumulative SG numbers in the northern and southern hemispheres - for simple SGs are different from those for complex SGs during SCs 12, 14, 18, and 21; and iii) there are discrepancies between the dominant hemispheres of simple and complex SGs for SCs 12, 14, 18, and 21.

Probability Estimates of Solar Proton Doses During Periods of Low Sunspot Number for Short Duration Missions

Science.gov (United States)

Atwell, William; Tylka, Allan J.; Dietrich, William F.; Rojdev, Kristina; Matzkind, Courtney

2016-01-01

In an earlier paper presented at ICES in 2015, we investigated solar particle event (SPE) radiation exposures (absorbed dose) to small, thinly-shielded spacecraft during a period when the monthly smoothed sunspot number (SSN) was less than 30. Although such months are generally considered "solar-quiet", SPEs observed during these months even include Ground Level Events, the most energetic type of SPE. In this paper, we add to previous study those SPEs that occurred in 1973-2015 when the SSN was greater than 30 but less than 50. Based on the observable energy range of the solar protons, we classify the event as GLEs, sub-GLEs, and sub-sub-GLEs, all of which are potential contributors to the radiation hazard. We use the spectra of these events to construct a probabilistic model of the absorbed dose due to solar protons when SSN < 50 at various confidence levels for various depths of shielding and for various mission durations. We provide plots and tables of solar proton-induced absorbed dose as functions of confidence level, shielding thickness, and mission-duration that will be useful to system designers.

Radar meteor rates and solar activity

International Nuclear Information System (INIS)

Prikryl, P.

1983-01-01

The short-term variation of diurnal radar meteor rates with solar activity represented by solar microwave flux Fsub(10.7), and sunspots relative number Rsub(z), is investigated. Applying the superposed-epoch analysis to the observational material of radar meteor rates from Christchurch (1960-61 and 1963-65), a decrease in the recorded radar rates is found during days of enhanced solar activity. No effect of geomagnetic activity similar to the one reported for the Swedish and Canadian radar meteor data was found by the author in the Christchurch data. A possible explanation of the absence of the geomagnetic effect on radar meteor rates from New Zealand due to a lower echo ceiling height of the Christchurch radar is suggested. The variation of the atmospheric parameters as a possible cause of the observed variation in radar meteor rates is also discussed. (author)

Evidence for cosmic ray modulation in temperature records from the South Atlantic Magnetic Anomaly region

Energy Technology Data Exchange (ETDEWEB)

Frigo, E. [Sao Paulo Univ. (Brazil). Dept. de Geofisica; Federal do Pampa Univ., Cacapava do Sul (Brazil); Pacca, I.G. [Sao Paulo Univ. (Brazil). Dept. de Geofisica; Pereira-Filho, A.J. [Sao Paulo Univ. (Brazil). Dept. de Ciencias Atmosfericas; Rampelloto, P.H. [Federal do Pampa Univ., Sao Gabriel (Brazil); Rigozo, N.R. [Instituto Nacional de Pesquisas Espaciais, Sao Jose dos Campos (Brazil). Div. de Geofisica Espacial

2013-11-01

Possible direct or indirect climatic effects related to solar variability and El Nino-Southern Oscillation (ENSO) were investigated in the southern Brazil region by means of the annual mean temperatures from four weather stations 2 degrees of latitude apart over the South Atlantic Magnetic Anomaly (SAMA) region. Four maximum temperature peaks are evident at all stations in 1940, 1958, 1977 and 2002. A spectral analysis indicates the occurrence of periodicities between 2 and 7 yr, most likely associated with ENSO, and periodicities of approximately 11 and 22 yr, normally associated with solar variability. Cross-wavelet analysis indicated that the signal associated with the 22 yr solar magnetic cycle was more persistent in the last decades, while the 11 yr sunspot cycle and ENSO periodicities were intermittent. Phase-angle analysis revealed that temperature variations and the 22 yr solar cycle were in anti-phase near the SAMA center. Results show an indirect indication of possible relationships between the variability of galactic cosmic rays and climate change on a regional scale.

Solar activity effects in the ionospheric D region

Directory of Open Access Journals (Sweden)

A. D. Danilov

1998-12-01

Full Text Available Variations in the D-region electron concentration within the solar activity cycle are considered. It is demonstrated that conclusions of various authors, who have analyzed various sets of experimental data on [e], differ significantly. The most reliable seem to be the conclusions based on analysis of the [e] measurements carried out by the Faraday rotation method and on the theoretical concepts on the D-region photochemistry. Possible QBO effects in the relation of [e] to solar activity are considered and an assumption is made that such effects may be the reason for the aforementioned disagreement in conclusions on the [e] relation to solar indices.Key words. Atmospheric composition and structure · Ion chemistry of the atmosphere · Middle atmosphere

Journal of Astrophysics and Astronomy | Indian Academy of Sciences

Indian Academy of Sciences (India)

2016-01-27

Jan 27, 2016 ... The positional measurements of sunspots from the Kodaikanal Observatory and Solar Geophysical data are used to study the association between occurrence of the abnormal activities of big sunspot groups that were observed during the period of October–November 2003 and occurrence of the flares.

The effects of activation procedures on regional cerebral blood flow in humans

International Nuclear Information System (INIS)

Rozenfeld, D.; Wolfson, L.I.

1981-01-01

Regional cerebral blood flow (r-CBF) can be measured using 133XE and collimated detectors. The radionuclide can be administered either by inhalation or intracarotid injection. Comparison of blood flow determinations at rest and during performance of an activity identifies those brain regions that become active during the performance of the activity. Relatively specific patterns of r-CBF are observed during hand movements, sensory stimulation, eye movements, speech, listening, and reading. Regional CBF changes during reasoning and memorization are less specific and less well characterized. It is clear that brain lesions affect r-CBF responses to various activities, but this effect has not been well correlated with functional deficits or recovery of function. Regional CBF measurement gives information about brain activity and the functional response to experimental manipulation. This approach may well add to our understanding of normal, as well as pathologic, brain functioning

Waste production and regional growth of marine activities an econometric model

International Nuclear Information System (INIS)

Bramati, Maria Caterina

2016-01-01

Coastal regions are characterized by intense human activity and climatic pressures, often intensified by competing interests in the use of marine waters. To assess the effect of public spending on the regional economy, an econometric model is here proposed. Not only are the regional investment and the climatic risks included in the model, but also variables related to the anthropogenic pressure, such as population, economic activities and waste production. Feedback effects of economic and demographic expansion on the pollution of coastal areas are also considered. It is found that dangerous waste increases with growing shipping and transportation activities and with growing population density in non-touristic coastal areas. On the other hand, the amount of non-dangerous wastes increases with marine mining, defense and offshore energy production activities. However, lower waste production occurs in areas where aquaculture and touristic industry are more exploited, and accompanied by increasing regional investment in waste disposal. - Highlights: • We use an econometric model as a tool for assessing the effects of regional policies on the development of economic activities related to the use of the sea and on the impact on the marine environment. • Through scenario simulation we provide strategic guidelines for policy makers and economic planners • The model features feedback effects of economic and demographic expansion on the pollution of coastal areas.

The Location of ICT activities in EU regions. Implications for regional policies

Directory of Open Access Journals (Sweden)

Salvador Barrios

2008-11-01

Full Text Available The location of ICT producing industries does matter for global competitivenessand long-run growth potential. For instance, the differing contribution ofICT to economic growth between the US and the EU is often mentioned as one of themain cause explaining the diverging growth performance of these two areas since themid-1990s. In turn, since the mid-1990s, countries with especially dynamic economicgrowth have tended to be highly specialized in ICT-producing and ICT-using industries,see van Ark and Inkaar (2005. More generally, ICT producing sectors, tendto promote technological change and innovative capability which are seen to be at thecore of economic growth and competitiveness. When considering the EU economy,ICT industries appear to be concentrated in a limited number of regions, see Koski etal. (2002 for empirical evidence. Afirst objective of the present paper is to documentthe location of ICT producing industries in European regions in order to map existingEU clusters as well as to analyze recent changes in these industries using recent dataon employment and firm location, especially in relation to the EU enlargement thathas taken place in May 2004. The location of the ICT-producing sectors is not the endof the story however. A crucial aspect concerns the nature of activities that are beingundertaken in different regions. Importantly, ICT industries do have different characteristicsin terms of human capital, skill requirement, and knowledge content. In particular,because of the positive association between human capital, knowledge andlong-run growth, it is important to analyze to what extent EU regional ICT clustersdiffer in according to these characteristics. The second question addressed in the paperconcerns the nature of ICT activities undertaken in EU regions. Finally, the paperprovides econometric estimates of the location of firms in ICT industries across EUregions. The paper considers more specifically the case of multinationals�

Organizational-economic maintenance of innovation activity in the region: comparative assessment

Directory of Open Access Journals (Sweden)

Nadezhda Igorevna Antipina

2014-05-01

Full Text Available The article proposes the approach to evaluate the organizational-economic maintenance of innovation activity in the regions in quantitative and qualitative indicators, as well as the method to calculate the assessment of regulatory support of this activity. It justifies the author’s approach of comparative efficiency evaluation of innovation legislation and regions’ innovation development level. The article gives the qualitative estimation of regulatory support of innovation development in the regions that are innovation leaders. It singles out key directions to develop regulatory support of innovation activity, which encourage RF subjects’ innovation activity

Approach to analysis of inter-regional similarity of investment activity support measures in legislation of regions (on the example of Krasnoyarsk region

Directory of Open Access Journals (Sweden)

Valentina F. Lapo

2017-01-01

Full Text Available The most part of stimulation methods in Russia are concentrated in legal documents of the regions of the Russian Federation. They directed on intensification of investment activity in regions. How similar are these investment stimulation conceptions? There is no mention in the literature of the methodical questions of quantitative analysis and inter-regional comparisons. In addition, there are no results of statistical research of inter-regional correlations of stimulation methods and analysis of dynamics of this process. There are no special measuring instruments. The presented work is aimed at completion of these blanks. The approach for the spatial correlation analysis of legislative norms is offered in research. Classification of investments’ stimulation methods is developed. The way of preparing and coding data for research is offered. The approach and system of coefficients for the analysis of inter-regional interrelations of legislative systems of investments’ stimulation is offered. A proximity coefficient of regional legislation, a factor of structure similarity and a dynamic coincidence index are proposed. The space-time base of investment stimulation methods on Russian Federation regions for 12 years is collected and statistically processed for research. There are only 758 documents. A source of texts is a site of the Ministry of Justice of the Russian Federation.Research of documents has allowed revealing a number of laws in formation of regional investment stimulation systems. The regions that are the most similar in terms of structure of stimulation methods are identified. We have found the group of regions for which it is observed the increase in similarity of the legislation and the group with the reduction of similarity. Therefore, it is obvious that the general trend to reduction of similarity in the legislation takes place between Krasnoyarsk territory and the other regions of the Russian Federation. Calculations have

Comprehensive Assessment of Integration Activity of Business Structures in Russian Regions

Directory of Open Access Journals (Sweden)

Mariya Gennad’evna Karelina

2016-11-01

Full Text Available In the context of economic sanctions and growing international isolation, the research into regional differences in integration development acquires special relevance for Russia; this fact determines the need for a comprehensive assessment of integration activity of business structures in Russian regions. The diversity of approaches to the study of problems and prospects of economic integration and the current debate about the role of integration processes in the development of regional economies determined a comprehensive approach to the concepts of “integration” and “integration activity” in order to create objective prerequisites for analyzing integration activity of business structures in the regions of Russia. The information base of the research is the data of Russian information and analytical agencies. The tools used in the research include methods for analyzing structural changes, methods for analyzing economic differentiation and concentration, nonparametric statistics methods, and econometric analysis methods. The first part of the paper shows that socio-economic development in constituent entities of Russia is closely connected with the operation of integrated business structures located on their territory. Having studied the structure and dynamics of integration activity, we reveal the growing heterogeneity of integration activity of business structures in Russian regions. The hypothesis about significant divergence of mergers and acquisitions for corporate structures in Russian regions was confirmed by high values of the Gini coefficient, the Herfindahl index and the decile differentiation coefficient. The second part of the paper contains a comparative analysis and proposes an econometric approach to the measurement of integration activity of business structures in subjects of the Russian Federation on the basis of integral synthetic categories. The approach we propose focuses on the development of a system of indicators

Drivers of Concentration of Economic Activity in Russia’s Regions

Directory of Open Access Journals (Sweden)

Svetlana Nikolaevna Rastvortseva

2016-05-01

Full Text Available The uneven distribution of economic activity in Russia promotes the differentiation of its constituent entities by level of development. Regions are independent participants of economic relations, and they often act as competitors rather than partners. Agglomeration effects arise in more successful regions and contribute to the concentration of resources, manufacturing enterprises, service providers, skilled workers, and scientific and technological knowledge. The aim of the study, the results of which are reflected in the paper, is to identify the factors and assess their impact on the concentration (dispersion of economic activity on the basis of Russia’s regions. The paper describes the benefits of agglomeration processes from the standpoint of economic geography, allocation theory and international trade theory. The concentration of economic activity in Russia’s regions is estimated by the Herfindahl–Hirschman index of industrial production taking into consideration the volume of investments in fixed capital and the number of people employed in the economy in Russia’s regions in 1990–2013. It is determined that fixed capital investments have the propensity to concentrate, but react strongly to economic crises. Labor resources, by contrast, are distributed relatively evenly, and their concentration in certain regions is increasing steadily. The article considers key factors such as wage growth, distance to large cities, direct foreign investment, road network density, the degree of development of the services sector in the region. The factor model is constructed using the least squares method. The authors conclude that the growth of wages in the region (relative to national average has a negative effect on the concentration of economic activity. There is a positive correlation between the growth of direct foreign investment and the density of hard surface roads. The development of services has the greatest positive impact on

Carnosine: effect on aging-induced increase in brain regional monoamine oxidase-A activity.

Science.gov (United States)

Banerjee, Soumyabrata; Poddar, Mrinal K

2015-03-01

Aging is a natural biological process associated with several neurological disorders along with the biochemical changes in brain. Aim of the present investigation is to study the effect of carnosine (0.5-2.5μg/kg/day, i.t. for 21 consecutive days) on aging-induced changes in brain regional (cerebral cortex, hippocampus, hypothalamus and pons-medulla) mitochondrial monoamine oxidase-A (MAO-A) activity with its kinetic parameters. The results of the present study are: (1) The brain regional mitochondrial MAO-A activity and their kinetic parameters (except in Km of pons-medulla) were significantly increased with the increase of age (4-24 months), (2) Aging-induced increase of brain regional MAO-A activity including its Vmax were attenuated with higher dosages of carnosine (1.0-2.5μg/kg/day) and restored toward the activity that observed in young, though its lower dosage (0.5μg/kg/day) were ineffective in these brain regional MAO-A activity, (3) Carnosine at higher dosage in young rats, unlike aged rats significantly inhibited all the brain regional MAO-A activity by reducing their only Vmax excepting cerebral cortex, where Km was also significantly enhanced. These results suggest that carnosine attenuated the aging-induced increase of brain regional MAO-A activity by attenuating its kinetic parameters and restored toward the results of MAO-A activity that observed in corresponding brain regions of young rats. Copyright © 2014 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

LONG-TERM VARIATION IN THE SUN’S ACTIVITY CAUSED BY MAGNETIC ROSSBY WAVES IN THE TACHOCLINE

Energy Technology Data Exchange (ETDEWEB)

Zaqarashvili, Teimuraz V. [Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, 8042 Graz (Austria); Oliver, Ramon; Ballester, Jose Luis [Departament de Física, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Hanslmeier, Arnold [Institute für Physik, Geophysik Astrophysik und Meteorologie, University of Graz, Univ.-Platz 5, 8010 Graz (Austria); Carbonell, Marc [Departament de Matemàtiques i Informàtica, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Gachechiladze, Tamar [Abastumani Astrophysical Observatory at Ilia State University, Tbilisi, Georgia (United States); Usoskin, Ilya G., E-mail: teimuraz.zaqarashvili@oeaw.ac.at [Sodankylä Geophysical Observatory and ReSoLVE Centre of Excellence, University of Oulu, FI-90014 Oulo (Finland)

2015-06-01

Long-term records of sunspot number and concentrations of cosmogenic radionuclides (10Be and 14C) on the Earth reveal the variation of the Sun's magnetic activity over hundreds and thousands of years. We identify several clear periods in sunspot, 10Be, and 14C data as 1000, 500, 350, 200, and 100 years. We found that the periods of the first five spherical harmonics of the slow magnetic Rossby mode in the presence of a steady toroidal magnetic field of 1200–1300 G in the lower tachocline are in perfect agreement with the timescales of observed variations. The steady toroidal magnetic field can be generated in the lower tachocline either due to the steady dynamo magnetic field for low magnetic diffusivity or due to the action of the latitudinal differential rotation on the weak poloidal primordial magnetic field, which penetrates from the radiative interior. The slow magnetic Rossby waves lead to variations of the steady toroidal magnetic field in the lower tachocline, which modulate the dynamo magnetic field and consequently the solar cycle strength. This result constitutes a key point for long-term prediction of the cycle strength. According to our model, the next deep minimum in solar activity is expected during the first half of this century.

LONG-TERM VARIATION IN THE SUN’S ACTIVITY CAUSED BY MAGNETIC ROSSBY WAVES IN THE TACHOCLINE

International Nuclear Information System (INIS)

Zaqarashvili, Teimuraz V.; Oliver, Ramon; Ballester, Jose Luis; Hanslmeier, Arnold; Carbonell, Marc; Gachechiladze, Tamar; Usoskin, Ilya G.

2015-01-01

Long-term records of sunspot number and concentrations of cosmogenic radionuclides (10Be and 14C) on the Earth reveal the variation of the Sun's magnetic activity over hundreds and thousands of years. We identify several clear periods in sunspot, 10Be, and 14C data as 1000, 500, 350, 200, and 100 years. We found that the periods of the first five spherical harmonics of the slow magnetic Rossby mode in the presence of a steady toroidal magnetic field of 1200–1300 G in the lower tachocline are in perfect agreement with the timescales of observed variations. The steady toroidal magnetic field can be generated in the lower tachocline either due to the steady dynamo magnetic field for low magnetic diffusivity or due to the action of the latitudinal differential rotation on the weak poloidal primordial magnetic field, which penetrates from the radiative interior. The slow magnetic Rossby waves lead to variations of the steady toroidal magnetic field in the lower tachocline, which modulate the dynamo magnetic field and consequently the solar cycle strength. This result constitutes a key point for long-term prediction of the cycle strength. According to our model, the next deep minimum in solar activity is expected during the first half of this century

The effect of line damping, magneto-optics and parasitic light on the derivation of sunspot vector magnetic fields

Science.gov (United States)

Skumanich, A.; Lites, B. W.

1985-01-01

The least square fitting of Stokes observations of sunspots using a Milne-Eddington-Unno model appears to lead, in many circumstances, to various inconsistencies such as anomalously large doppler widths and, hence, small magnetic fields which are significantly below those inferred solely from the Zeeman splitting in the intensity profile. It is found that the introduction of additional physics into the model such as the inclusion of damping wings and magneto-optic birefrigence significantly improves the fit to Stokes parameters. Model fits excluding the intensity profile, i.e., of both magnitude as well as spectral shape of the polarization parameters alone, suggest that parasitic light in the intensity profile may also be a source of inconsistencies. The consequences of the physical changes on the vector properties of the field derived from the Fe I lambda 6173 line for the 17 November 1975 spot as well as on the thermodynamic state are discussed. A Doppler width delta lambda (D) - 25mA is bound to be consistent with a low spot temperature and microturbulence, and a damping constant of a = 0.2.

Comparison of GPS-TEC measurements with NeQuick2 and IRI model predictions in the low latitude East African region during varying solar activity period (1998 and 2008-2015)

Science.gov (United States)

Mengistu, E.; Damtie, B.; Moldwin, M. B.; Nigussie, M.

2018-03-01

This paper examines the performances of NeQuick2, the latest available IRI-2016, IRI-2012 and IRI-2007 models in describing the monthly and seasonal mean total electron content (TEC) over the East African region. This is to gain insight into the success of the various model types and versions at characterizing the ionosphere within the equatorial ionization anomaly. TEC derived from five Global Positioning System (GPS) receivers installed at Addis Ababa (ADD, 5.33°N, 111.99°E Geog.), Asab (ASAB, 8.67°N, 116.44°E Geog.), Ambo (ABOO, 5.43°N, 111.05°E Geog.), Nairobi (RCMN, -4.48°N, 108.46°E Geog.) and Nazret (NAZR, 4.78°N, 112.43°E Geog.), are compared with the corresponding values computed using those models during varying solar activity period (1998 and 2008-2015). We found that different models describe the equatorial and anomaly region ionosphere best depending on solar cycle, season and geomagnetic activity levels. Our results show that IRI-2016 is the best model (compared to others in terms of discrepancy range) in estimating the monthly mean GPS-TEC at NAZR, ADD and RCMN stations except at ADD during 2008 and 2012. It is also found that IRI-2012 is the best model in estimating the monthly mean TEC at ABOO station in 2014. IRI show better agreement with observations during June solstice for all the years studied at ADD except in 2012 where NeQuick2 better performs. At NAZR, NeQuick2 better performs in estimating seasonal mean GPS-TEC during 2011, while IRI models are best during 2008-2009. Both NeQuick2 and IRI models underestimate measured TEC for all the seasons at ADD in 2010 but overestimate at NAZR in 2009 and RCMN in 2008. The periodic variations of experimental and modeled TEC have been compared with solar and geomagnetic indices at ABOO and ASAB in 2014 and results indicate that the F10.7 and sunspot number as indices of solar activity seriously affects the TEC variations with periods of 16-32 days followed by the geomagnetic activity on

Photospheric Velocity Structures during the Emergence of Small Active Regions on the Sun

International Nuclear Information System (INIS)

Khlystova, Anna; Toriumi, Shin

2017-01-01

We study the plasma flows in the solar photosphere during the emergence of two small active regions, NOAA 9021 and 10768. Using Solar and Heliospheric Observatory /Michelson Doppler Imager data, we find that the strong plasma upflows appear at the initial stage of active region formation, with maximum upflow velocities of −1650 and −1320 m s −1 . The structures with enhanced upflows have size ∼8 Mm in diameter, and they exist for 1–2 hr. The parameters of the enhanced upflows are consistent with those of the large active region NOAA 10488, which may suggest the possibility that the elementary emerging magnetic loops that appear at the earliest phase of active region formation have similar properties, irrespective of scales of active regions. Comparison between the observations and a numerical simulation of magnetic flux emergence shows a striking consistency. We find that the driving force of the plasma upflow is at first the gas pressure gradient and later the magnetic pressure gradient.

Photospheric Velocity Structures during the Emergence of Small Active Regions on the Sun

Energy Technology Data Exchange (ETDEWEB)

Khlystova, Anna [Institute of Solar-Terrestrial Physics SB RAS, Lermontov St., 126a, 664033 Irkutsk (Russian Federation); Toriumi, Shin, E-mail: hlystova@iszf.irk.ru, E-mail: shin.toriumi@nao.ac.jp [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

2017-04-10

We study the plasma flows in the solar photosphere during the emergence of two small active regions, NOAA 9021 and 10768. Using Solar and Heliospheric Observatory /Michelson Doppler Imager data, we find that the strong plasma upflows appear at the initial stage of active region formation, with maximum upflow velocities of −1650 and −1320 m s{sup −1}. The structures with enhanced upflows have size ∼8 Mm in diameter, and they exist for 1–2 hr. The parameters of the enhanced upflows are consistent with those of the large active region NOAA 10488, which may suggest the possibility that the elementary emerging magnetic loops that appear at the earliest phase of active region formation have similar properties, irrespective of scales of active regions. Comparison between the observations and a numerical simulation of magnetic flux emergence shows a striking consistency. We find that the driving force of the plasma upflow is at first the gas pressure gradient and later the magnetic pressure gradient.

LOCAL DEVELOPMENT IN NORTHEST REGION THROUGH ACTIVITIES IN ITC DOMAIN

Directory of Open Access Journals (Sweden)

Daniela\tENACHESCU

2015-06-01

Full Text Available Economic areas with high technology are key drivers in sustainable regional development, including unemployment and consequently decreasing population migration in the region. Northeast Region is the largest development region of Romania in terms of number of inhabitants and the owned area. On 01/01/2014, according to balance employment, labor resources of the region were numbered 2,428,700, which represent 49.6% of employed population. The registered unemployment rate at 31 August 2014 was 6.5%, with 82 thousand unemployed registered. In terms of participation in the main economic activities, civilian employment in agriculture, forestry and fishing is predominant (40.1% while in service, civilian employment is 37.1%, while industry and construction is 22.8%. The paper aims to analyze the situation that the potential employment and development opportunities for the Northeast region through activities in the field of ITC domain. Unfortunately, this area was the worst in most indicators, the use of computers and the internet to the turnover of companies and investments in the IT & C and unfortunately in terms of employment population that is under 50%

Derivation of a regional active-optical reflectance sensor corn algorithm

Science.gov (United States)

Active-optical reflectance sensor (AORS) algorithms developed for in-season corn (Zea mays L.) N management have traditionally been derived using sub-regional scale information. However, studies have shown these previously developed AORS algorithms are not consistently accurate when used on a region...

Solar UV radiation variations and their stratospheric and climatic effects

Science.gov (United States)

Donnelly, R. F.; Heath, D. F.

1985-01-01

Nimbus-7 SBUV measurements of the short-term solar UV variations caused by solar rotation and active-region evolution have determined the amplitude and wavelength dependence for the active-region component of solar UV variations. Intermediate-term variations lasting several months are associated with rounds of major new active regions. The UV flux stays near the peak value during the current solar cycle variation for more than two years and peaks about two years later than the sunspot number. Nimbus-7 measurements have observed the concurrent stratospheric ozone variations caused by solar UV variations. There is now no doubt that solar UV variations are an important cause of short- and long-term stratospheric variations, but the strength of the coupling to the troposphere and to climate has not yet been proven.

FINE MAGNETIC FEATURES AND CHIRALITY IN SOLAR ACTIVE REGION NOAA 10930

International Nuclear Information System (INIS)

Zhang Hongqi

2010-01-01

In this paper, we present fine magnetic features near the magnetic inversion line in the solar active region NOAA 10930. The high-resolution vector magnetograms obtained by Hinode allow detailed analyses around magnetic fibrils in the active region. The analyses are based on the fact that the electric current density can be divided into two components: the shear component caused by the magnetic inhomogeneity and the twist component caused by the magnetic field twist. The relationships between magnetic field, electric current density, and its two components are examined. It is found that the individual magnetic fibrils are dominated by the current density component caused by the magnetic inhomogeneity, while the large-scale magnetic region is generally dominated by the electric current component associated with the magnetic twist. The microstructure of the magnetic field in the solar atmosphere is far from the force-free field. The current mainly flows around the magnetic flux fibrils in the active regions.

A 3-Step Algorithm Using Region-Based Active Contours for Video Objects Detection

Directory of Open Access Journals (Sweden)

Stéphanie Jehan-Besson

2002-06-01

Full Text Available We propose a 3-step algorithm for the automatic detection of moving objects in video sequences using region-based active contours. First, we introduce a very full general framework for region-based active contours with a new Eulerian method to compute the evolution equation of the active contour from a criterion including both region-based and boundary-based terms. This framework can be easily adapted to various applications, thanks to the introduction of functions named descriptors of the different regions. With this new Eulerian method based on shape optimization principles, we can easily take into account the case of descriptors depending upon features globally attached to the regions. Second, we propose a 3-step algorithm for detection of moving objects, with a static or a mobile camera, using region-based active contours. The basic idea is to hierarchically associate temporal and spatial information. The active contour evolves with successively three sets of descriptors: a temporal one, and then two spatial ones. The third spatial descriptor takes advantage of the segmentation of the image in intensity homogeneous regions. User interaction is reduced to the choice of a few parameters at the beginning of the process. Some experimental results are supplied.

The Harm that Underestimation of Uncertainty Does to Our Community: A Case Study Using Sunspot Area Measurements

Science.gov (United States)

Munoz-Jaramillo, Andres

2017-08-01

Data products in heliospheric physics are very often provided without clear estimates of uncertainty. From helioseismology in the solar interior, all the way to in situ solar wind measurements beyond 1AU, uncertainty estimates are typically hard for users to find (buried inside long documents that are separate from the data products), or simply non-existent.There are two main reasons why uncertainty measurements are hard to find:1. Understanding instrumental systematic errors is given a much higher priority inside instrumental teams.2. The desire to perfectly understand all sources of uncertainty postpones indefinitely the actual quantification of uncertainty in our measurements.Using the cross calibration of 200 years of sunspot area measurements as a case study, in this presentation we will discuss the negative impact that inadequate measurements of uncertainty have on users, through the appearance of toxic and unnecessary controversies, and data providers, through the creation of unrealistic expectations regarding the information that can be extracted from their data. We will discuss how empirical estimates of uncertainty represent a very good alternative to not providing any estimates at all, and finalize by discussing the bare essentials that should become our standard practice for future instruments and surveys.

The Effect of "Rogue" Active Regions on the Solar Cycle

Science.gov (United States)

Nagy, Melinda; Lemerle, Alexandre; Labonville, François; Petrovay, Kristóf; Charbonneau, Paul

2017-11-01

The origin of cycle-to-cycle variations in solar activity is currently the focus of much interest. It has recently been pointed out that large individual active regions with atypical properties can have a significant impact on the long-term behavior of solar activity. We investigate this possibility in more detail using a recently developed 2×2D dynamo model of the solar magnetic cycle. We find that even a single "rogue" bipolar magnetic region (BMR) in the simulations can have a major effect on the further development of solar activity cycles, boosting or suppressing the amplitude of subsequent cycles. In extreme cases, an individual BMR can completely halt the dynamo, triggering a grand minimum. Rogue BMRs also have the potential to induce significant hemispheric asymmetries in the solar cycle. To study the effect of rogue BMRs in a more systematic manner, a series of dynamo simulations were conducted, in which a large test BMR was manually introduced in the model at various phases of cycles of different amplitudes. BMRs emerging in the rising phase of a cycle can modify the amplitude of the ongoing cycle, while BMRs emerging in later phases will only affect subsequent cycles. In this model, the strongest effect on the subsequent cycle occurs when the rogue BMR emerges around cycle maximum at low latitudes, but the BMR does not need to be strictly cross-equatorial. Active regions emerging as far as 20° from the equator can still have a significant effect. We demonstrate that the combined effect of the magnetic flux, tilt angle, and polarity separation of the BMR on the dynamo is via their contribution to the dipole moment, δ D_{BMR}. Our results indicate that prediction of the amplitude, starting epoch, and duration of a cycle requires an accurate accounting of a broad range of active regions emerging in the previous cycle.

What can the annual 10Be solar activity reconstructions tell us about historic space weather?

Science.gov (United States)

Barnard, Luke; McCracken, Ken G.; Owens, Mat J.; Lockwood, Mike

2018-04-01

Context: Cosmogenic isotopes provide useful estimates of past solar magnetic activity, constraining past space climate with reasonable uncertainty. Much less is known about past space weather conditions. Recent advances in the analysis of 10Be by McCracken & Beer (2015, Sol Phys 290: 305-3069) (MB15) suggest that annually resolved 10Be can be significantly affected by solar energetic particle (SEP) fluxes. This poses a problem, and presents an opportunity, as the accurate quantification of past solar magnetic activity requires the SEP effects to be determined and isolated, whilst doing so might provide a valuable record of past SEP fluxes. Aims: We compare the MB15 reconstruction of the heliospheric magnetic field (HMF), with two independent estimates of the HMF derived from sunspot records and geomagnetic variability. We aim to quantify the differences between the HMF reconstructions, and speculate on the origin of these differences. We test whether the differences between the reconstructions appear to depend on known significant space weather events. Methods: We analyse the distributions of the differences between the HMF reconstructions. We consider how the differences vary as a function of solar cycle phase, and, using a Kolmogorov-Smirnov test, we compare the distributions under the two conditions of whether or not large space weather events were known to have occurred. Results: We find that the MB15 reconstructions are generally marginally smaller in magnitude than the sunspot and geomagnetic HMF reconstructions. This bias varies as a function of solar cycle phase, and is largest in the declining phase of the solar cycle. We find that MB15's excision of the years with very large ground level enhancement (GLE) improves the agreement of the 10Be HMF estimate with the sunspot and geomagnetic reconstructions. We find no statistical evidence that GLEs, in general, affect the MB15 reconstruction, but this analysis is limited by having too few samples. We do find

Solar Flares and Their Prediction

Science.gov (United States)

Adams, Mitzi L.

1999-01-01

Solar flares and coronal mass ejection's (CMES) can strongly affect the local environment at the Earth. A major challenge for solar physics is to understand the physical mechanisms responsible for the onset of solar flares. Flares, characterized by a sudden release of energy (approx. 10(exp 32) ergs for the largest events) within the solar atmosphere, result in the acceleration of electrons, protons, and heavier ions as well as the production of electromagnetic radiation from hard X-rays to km radio waves (wavelengths approx. = 10(exp -9) cm to 10(exp 6) cm). Observations suggest that solar flares and sunspots are strongly linked. For example, a study of data from 1956-1969, reveals that approx. 93 percent of major flares originate in active regions with spots. Furthermore, the global structure of the sunspot magnetic field can be correlated with flare activity. This talk will review what we know about flare causes and effects and will discuss techniques for quantifying parameters, which may lead to a prediction of solar flares.

Universities and Economic Development Activities: A UK Regional Comparison

Science.gov (United States)

Decter, Moira; Cave, Frank; Rose, Mary; Peers, Gill; Fogg, Helen; Smith, Susan M.

2011-01-01

A number of UK universities prioritize economic development or regeneration activities and for some of these universities such activities are the main focus of their knowledge transfer work. This study compares two regions of the UK--the North West and the South East of England--which have very different levels of economic performance.…

A GEOMETRICAL HEIGHT SCALE FOR SUNSPOT PENUMBRAE

International Nuclear Information System (INIS)

Puschmann, K. G.; Ruiz Cobo, B.; MartInez Pillet, V.

2010-01-01

Inversions of spectropolarimetric observations of penumbral filaments deliver the stratification of different physical quantities in an optical depth scale. However, without establishing a geometrical height scale, their three-dimensional geometrical structure cannot be derived. This is crucial in understanding the correct spatial variation of physical properties in the penumbral atmosphere and to provide insights into the mechanism capable of explaining the observed penumbral brightness. The aim of this work is to determine a global geometrical height scale in the penumbra by minimizing the divergence of the magnetic field vector and the deviations from static equilibrium as imposed by a force balance equation that includes pressure gradients, gravity, and the Lorentz force. Optical depth models are derived from the inversion of spectropolarimetric data of an active region observed with the Solar Optical Telescope on board the Hinode satellite. We use a genetic algorithm to determine the boundary condition for the inference of geometrical heights. The retrieved geometrical height scale permits the evaluation of the Wilson depression at each pixel and the correlation of physical quantities at each height. Our results fit into the uncombed penumbral scenario, i.e., a penumbra composed of flux tubes with channeled mass flow and with a weaker and more horizontal magnetic field as compared with the background field. The ascending material is hotter and denser than their surroundings. We do not find evidence of overturning convection or field-free regions in the inner penumbral area analyzed. The penumbral brightness can be explained by the energy transfer of the ascending mass carried by the Evershed flow, if the physical quantities below z = -75 km are extrapolated from the results of the inversion.

A study of the asymmetrical distribution of solar activity features on solar and plasma parameters (1967-2016)

Science.gov (United States)

El-Borie, M. A.; El-Taher, A. M.; Aly, N. E.; Bishara, A. A.

2018-04-01

The impact of asymmetrical distribution of hemispheric sunspot areas (SSAs) on the interplanetary magnetic field, plasma, and solar parameters from 1967 to 2016 has been studied. The N-S asymmetry of solar-plasma activities based on SSAs has a northern dominance during solar cycles 20 and 24. However, it has a tendency to shift to the southern hemisphere in cycles 21, 22, and 23. The solar cycle 23 showed that the sorted southern SSAs days predominated over the northern days by ˜17%. Through the solar cycles 21-24, the SSAs of the southern hemisphere were more active. In contrast, the northern SSAs predominate over the southern one by 9% throughout solar cycle 20. On the other hand, the average differences of field magnitude for the sorted northern and southern groups during solar cycles 20-24 are statistically insignificant. Clearly, twenty years showed that the solar plasma ion density from the sorted northern group was denser than that of southern group and a highest northern dominant peak occurred in 1971. In contrast, seventeen out of fifty years showed the reverse. In addition, there are fifteen clear asymmetries of solar wind speed (SWS), with SWS (N) > SWS (S), and during the years 1972, 2002, and 2008, the SWS from the sorted northern group was faster than that of southern activity group by 6.16 ± 0.65 km/s, 5.70 ± 0.86 km/s, and 5.76 ± 1.35 km/s, respectively. For the solar cycles 20-24, the grand-averages of P from the sorted solar northern and southern have nearly the same parameter values. The solar plasma was hotter for the sorted northern activity group than the southern ones for 17 years out of 50. Most significant northern prevalent asymmetries were found in 1972 (5.76 ± 0.66 × 103 K) and 1996 (4.7 ± 0.8 × 103 K), while two significant equivalent dominant southern asymmetries (˜3.8 ± 0.3 × 103 K) occurred in 1978 and 1993. The grand averages of sunspot numbers have symmetric activity for the two sorted northern and southern hemispheres

Positron-emission tomography of brain regions activated by recognition of familiar music.

Science.gov (United States)

Satoh, M; Takeda, K; Nagata, K; Shimosegawa, E; Kuzuhara, S

2006-05-01

We can easily recognize familiar music by listening to only one or 2 of its opening bars, but the brain regions that participate in this cognitive processing remain undetermined. We used positron-emission tomography (PET) to study changes in regional cerebral blood flow (rCBF) that occur during listening to familiar music. We used a PET subtraction technique to elucidate the brain regions associated with the recognition of familiar melodies such as well-known nursery tunes. Nonmusicians performed 2 kinds of musical tasks: judging the familiarity of musical pieces (familiarity task) and detecting deliberately altered notes in the pieces (alteration-detecting task). During the familiarity task, bilateral anterior portions of bilateral temporal lobes, superior temporal regions, and parahippocampal gyri were activated. The alteration-detecting task bilaterally activated regions in the precunei, superior/inferior parietal lobules, and lateral surface of frontal lobes, which seemed to show a correlation with the analysis of music. We hypothesize that during the familiarity task, activated brain regions participate in retrieval from long-term memory and verbal and emotional processing of familiar melodies. Our results reinforced the hypothesis reported in the literature as a result of group and case studies, that temporal lobe regions participate in the recognition of familiar melodies.

Crossmodal Activation of Visual Object Regions for Auditorily Presented Concrete Words

Directory of Open Access Journals (Sweden)

Jasper J F van den Bosch

2011-10-01

Full Text Available Dual-coding theory (Paivio, 1986 postulates that the human mind represents objects not just with an analogous, or semantic code, but with a perceptual representation as well. Previous studies (eg, Fiebach & Friederici, 2004 indicated that the modality of this representation is not necessarily the one that triggers the representation. The human visual cortex contains several regions, such as the Lateral Occipital Complex (LOC, that respond specifically to object stimuli. To investigate whether these principally visual representations regions are also recruited for auditory stimuli, we presented subjects with spoken words with specific, concrete meanings (‘car’ as well as words with abstract meanings (‘hope’. Their brain activity was measured with functional magnetic resonance imaging. Whole-brain contrasts showed overlap between regions differentially activated by words for concrete objects compared to words for abstract concepts with visual regions activated by a contrast of object versus non-object visual stimuli. We functionally localized LOC for individual subjects and a preliminary analysis showed a trend for a concreteness effect in this region-of-interest on the group level. Appropriate further analysis might include connectivity and classification measures. These results can shed light on the role of crossmodal representations in cognition.

Armenia as a Regional Centre for Astronomy for Development activities

Science.gov (United States)

Mickaelian, A.

2015-03-01

The Byurakan Astrophysical Observatory (BAO, Armenia, http://www.bao.am) are among the candidate IAU Regional Nodes for Astronomy for Development activities. It is one of the main astronomical centers of the former Soviet Union and the Middle East region. At present there are 48 qualified researchers at BAO, including six Doctors of Science and 30 PhDs. Five important observational instruments are installed at BAO, the larger ones being 2.6m Cassegrain (ZTA-2.6) and 1m Schmidt (the one that provided the famous Markarian survey). BAO is regarded as a national scientific-educational center, where a number of activities are being organized, such as: international conferences (4 IAU symposia and 1 IAU colloquium, JENAM-2007, etc.), small workshops and discussions, international summer schools (1987, 2006, 2008 and 2010), and Olympiads. BAO collaborates with scientists from many countries. The Armenian Astronomical Society (ArAS, http://www.aras.am/) is an NGO founded in 2001; it has 93 members and it is rather active in the organization of educational, amateur, popular, promotional and other matters. The Armenian Virtual Observatory (ArVO, http://www.aras.am/Arvo/arvo.htm) is one of the 17 national VO projects forming the International Virtual Observatories Alliance (IVOA) and is the only VO project in the region serving also for educational purposes. A number of activities are planned, such as management, coordination and evaluation of the IAU programs in the area of development and education, establishment of the new IAU endowed lectureship program and organization of seminars and public lectures, coordination and initiation of fundraising activities for astronomy development, organization of regional scientific symposia, conferences and workshops, support to Galileo Teacher Training Program (GTTP), production/publication of educational and promotional materials, etc.

Regional differences in commuting activities of inhabitants in the Tokyo metropolitan suburb

Directory of Open Access Journals (Sweden)

Masaki Kawase

2004-12-01

Full Text Available The purpose of this study is to elucidate gender differences and regional differences of co-mmuting activities by inhabitants in Japanese metropolitan suburbs. I found the different parts by districts in the metropolitan suburb. Regional factors cause gender differences in commuting activities and result in regional differences: In residential areas, inhabitants who work in metropolitan centers occupy much of the population. In older built-up areas, there are many “local” persons. In rural areas, motorization is progressing because access to rail-roads has been inconvenient. These regional factors influence the behavioral characteristics of commuting by married men, married women, never married men and never married women.

Perceived built environment and physical activity in U.S. women by sprawl and region.

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Troped, Philip J; Tamura, Kosuke; Whitcomb, Heather A; Laden, Francine

2011-11-01

A number of studies have demonstrated relationships between the perceived built environment and physical activity among adults. However, little is known about whether these associations differ by U.S. region and level of urban sprawl. To examine associations between the perceived built environment and physical activity in U.S. women by region and urban sprawl. Nurses' Health Study II participants (N=68,968) completed four perceived neighborhood environment survey items in 2005. Logistic regression was used to estimate associations with meeting physical activity recommendations, adjusting for demographic and weight-status variables, and stratifying by region and sprawl. Data analyses were completed in 2011. Perceived proximity to shops/stores was positively associated with physical activity across regions and levels of sprawl (ORs=1.21-1.46). Perceived access to recreation facilities was also a positive physical activity correlate in most region-sprawl strata, with strongest relationships found in the West (ORs=1.31-1.70). Perceived crime and presence of sidewalks did not show statistically significant associations with physical activity in most region-sprawl strata, although ORs for perceived crime showed a consistent pattern of negative associations (ORs=0.60-0.95). A higher number of positive environmental attributes was associated with a greater odds of meeting physical activity recommendations. Findings indicate that perceived proximity to shops/stores and access to recreation facilities are important correlates of physical activity for women, irrespective of region or sprawl. Copyright © 2011 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.

Prediction of solar activity from solar background magnetic field variations in cycles 21-23

International Nuclear Information System (INIS)

Shepherd, Simon J.; Zharkov, Sergei I.; Zharkova, Valentina V.

2014-01-01

A comprehensive spectral analysis of both the solar background magnetic field (SBMF) in cycles 21-23 and the sunspot magnetic field in cycle 23 reported in our recent paper showed the presence of two principal components (PCs) of SBMF having opposite polarity, e.g., originating in the northern and southern hemispheres, respectively. Over a duration of one solar cycle, both waves are found to travel with an increasing phase shift toward the northern hemisphere in odd cycles 21 and 23 and to the southern hemisphere in even cycle 22. These waves were linked to solar dynamo waves assumed to form in different layers of the solar interior. In this paper, for the first time, the PCs of SBMF in cycles 21-23 are analyzed with the symbolic regression technique using Hamiltonian principles, allowing us to uncover the underlying mathematical laws governing these complex waves in the SBMF presented by PCs and to extrapolate these PCs to cycles 24-26. The PCs predicted for cycle 24 very closely fit (with an accuracy better than 98%) the PCs derived from the SBMF observations in this cycle. This approach also predicts a strong reduction of the SBMF in cycles 25 and 26 and, thus, a reduction of the resulting solar activity. This decrease is accompanied by an increasing phase shift between the two predicted PCs (magnetic waves) in cycle 25 leading to their full separation into the opposite hemispheres in cycle 26. The variations of the modulus summary of the two PCs in SBMF reveals a remarkable resemblance to the average number of sunspots in cycles 21-24 and to predictions of reduced sunspot numbers compared to cycle 24: 80% in cycle 25 and 40% in cycle 26.

LOW-FREQUENCY OBSERVATIONS OF TRANSIENT QUASI-PERIODIC RADIO EMISSION FROM THE SOLAR ATMOSPHERE

Energy Technology Data Exchange (ETDEWEB)

Sasikumar Raja, K.; Ramesh, R., E-mail: sasikumar@iiap.res.in [Indian Institute of Astrophysics, II Block, Koramangala, Bangalore 560 034 (India)

2013-09-20

We report low-frequency observations of quasi-periodic, circularly polarized, harmonic type III radio bursts whose associated sunspot active regions were located close to the solar limb. The measured periodicity of the bursts at 80 MHz was ≈5.2 s, and their average degree of circular polarization (dcp) was ≈0.12. We calculated the associated magnetic field B (1) using the empirical relationship between the dcp and B for the harmonic type III emission, and (2) from the observed quasi-periodicity of the bursts. Both the methods result in B ≈ 4.2 G at the location of the 80 MHz plasma level (radial distance r ≈ 1.3 R{sub ☉}) in the active region corona.

Abundance variations in solar active regions

Science.gov (United States)

Strong, K. T.; Lemen, J. R.; Linford, G. A.

1991-01-01

The diversity in the published values of coronal abundances is unsettling, especially as the range of results seems to be beyond the quoted uncertainties. Measurements of the relative abundance of iron and neon derived from soft X-ray spectra of active regions are presented. From a data base of over 200 spectra taken by the Solar Maximum Mission Flat Crystal Spectrometer, it is found that the relative abundance can vary by as much as a factor of about 7 and can change on timescales of less than 1 h.

Geometrical relationship of flare-generated solar wind structures to the magnetic axes of bipolar sunspot groups adjacent to their originating solar flares

International Nuclear Information System (INIS)

Ivanov, K.G.; Evdokimova, L.V.; Mikerina, N.V.

1982-01-01

Occurrences of interplanetary shock waves near the Earth after the powerful isolated flares of 1957-1978 are investigated. The close connection between the occurrences of shock waves and the positions of magnetic axes of bipolar groups of sunspots is suggested on the basis of a statistical study. The shock waves are principally observed when the Earth finds itself near the planes that are projected through the flares in parallel to the appropriate magnetic axes of the nearest bipolar groups. This regularity is interpreted as an indirect argument for a three-dimensional geometry for the interplanetary shock waves which, when projected on these flattened to corresponding planes, are traces of large circular arcs. The typical angular scales of isolated interplanetary shock waves are estimated as approx. equal to 150 0 and approx. equal to 30 0 parallel and perpendicular, respectively, to the magnetic axes correspondingly. (orig.)

Mass motions in impulsive flarelike brightenings as observed by OSO 8

International Nuclear Information System (INIS)

Bruner, E.C. Jr.; Lites, B.W.

1979-01-01

CIV lambda1548 line profiles obtained with the University of Colorado spectrometer aboard OSO 8 reveal transient, redshifted brightenings in the chromosphere-corona transition region above active regions and sunspots. In these events the intensity rises by factors of up to 5 in less than the profile sampling interval of 27 s. These events indicate that the emitting material is moving downward at velocities of up to 30 km s -1 . The increase in line intensity and the amount of motion are consistent with the interpretation of these events as pressure waves propagating down magnetic flux loops

Mass motions in impulsive flarelike brightenings as observed by OSO 8. [mechanism response for solar flares

Science.gov (United States)

Bruner, E. C., Jr.; Lites, B. W.

1979-01-01

C IV 1548-A line profiles obtained with the University of Colorado spectrometer aboard OSO 8 reveal transient, redshifted brightenings in the chromosphere-corona transition region above active regions and sunspots. In these events the intensity rises by factors of up to 5 in less than the profile sampling interval of 27 sec. These events indicate that the emitting material is moving downward at velocities of up to 30 km/sec. The increase in line intensity and the amount of motion are consistent with the interpretation of these events as pressure waves propagating down magnetic flux loops.

Actively Learning about the Active Sun: Using JHelioviewer in Undergraduate Astronomy

Science.gov (United States)

Stage, Michael D.

2018-06-01

Solar phenomena of the chromosphere, corona and photosphere are only truly revealed through multi-wavelength and time-dependent study. While one can show slides of models of the solar convection zone, videos of granulation, and magnetogram and UV images, it is now possible to engage students much more fully in learning about dynamic solar phenomena such as the evolution of sunspots and the magentic field. JHelioviewer is professional solar visualization tool developed by an international team as part of the ESA/NASA Helioviewer project (Muller et al., 2017, A&A 606, A10), which allows users to select and overlay movies of solar data from multiple instruments of multiple satellite and ground-based observatories, with complete control over time-sequencing, image overlays, solar coordinate grids, rotational tracking, and export functions. I developed materials using the viewer for my sophomore-level undergraduate solar astronomy course to introduce students to the dynamics of the solar surface and atmosphere. The lab-like projects, suitable for in-class, labs, or home-work assignments, allow students to watch the formation, strengthening, movement, and dissipation of sunspots; to classify spots; to study the magnetic flux tubes connecting spots; to see reconnection; to learn about the solar coordinate systems (Stonyhurst, Carrington, etc.); to see how line emission (H-alpha, C, Fe and He UV lines from SDO, etc.) traces the structure of the atmosphere at different heights and temperatures; to observe the Wilson effect; and to measure motions such as moat flow and photospheric flow by tracking individual elements in magnetograms. In this presentation I share my activities and approach, which can be tailored to suit gen-ed, intermediate, or advanced astrophysics majors. (The author has no connection with the JHelioviewer project or team.)

Radiative and magnetic properties of solar active regions. II. Spatially resolved analysis of O V 62.97 nm transition region emission

Science.gov (United States)

Fludra, A.; Warren, H.

2010-11-01

Context. Global relationships between the photospheric magnetic flux and the extreme ultraviolet emission integrated over active region area have been studied in a previous paper by Fludra & Ireland (2008, A&A, 483, 609). Spatially integrated EUV line intensities are tightly correlated with the total unsigned magnetic flux, and yet these global power laws have been shown to be insufficient for accurately determining the coronal heating mechanism owing to the mathematical ill-conditioning of the inverse problem. Aims: Our aim is to establish a relationship between the EUV line intensities and the photospheric magnetic flux density on small spatial scales in active regions and investigate whether it provides a way of identifying the process that heats the coronal loops. Methods: We compare spatially resolved EUV transition region emission and the photospheric magnetic flux density. This analysis is based on the O V 62.97 nm line recorded by the SOHO Coronal Diagnostic Spectrometer (CDS) and SOHO MDI magnetograms for six solar active regions. The magnetic flux density ϕ is converted to a simulated O V intensity using a model relationship I(ϕ, L) = Cϕδ Lλ, where the loop length L is obtained from potential magnetic field extrapolations. This simulated spatial distribution of O V intensities is convolved with the CDS instrument's point spread function and compared pixel by pixel with the observed O V line intensity. Parameters δ and λ are derived to give the best fit for the observed and simulated intensities. Results: Spatially-resolved analysis of the transition region emission reveals the complex nature of the heating processes in active regions. In some active regions, particularly large, local intensity enhancements up to a factor of five are present. When areas with O V intensities above 3000 erg cm-2 s-1 sr-1 are ignored, a power law has been fitted to the relationship between the local O V line intensity and the photospheric magnetic flux density in each

Babcock Redux: An Amendment of Babcock's Schematic of the Sun's Magnetic Cycle

Science.gov (United States)

Moore, Ronald L.; Cirtain, Jonathan W.; Sterling, Alphonse C.

2017-08-01

We amend Babcock's original scenario for the global dynamo process that sustains the Sun's 22-year magnetic cycle. The amended scenario fits post-Babcock observed features of the magnetic activity cycle and convection zone, and is based on ideas of Spruit & Roberts (1983, Nature, 304, 401) about magnetic flux tubes in the convection zone. A sequence of four schematic cartoons lays out the proposed evolution of the global configuration of the magnetic field above, in, and at the bottom of the convection zone through sunspot Cycle 23 and into Cycle 24. Three key elements of the amended scenario are: (1) as the net following-polarity magnetic field from the sunspot-region Ω-loop fields of an ongoing sunspot cycle is swept poleward to cancel and replace the opposite-polarity polar-cap field from the previous sunspot cycle, it remains connected to the ongoing sunspot cycle's toroidal source-field band at the bottom of the convection zone; (2) topological pumping by the convection zone's free convection keeps the horizontal extent of the poleward-migrating following-polarity field pushed to the bottom, forcing it to gradually cancel and replace old horizontal field below it that connects the ongoing-cycle source-field band to the previous-cycle polar-cap field; (3) in each polar hemisphere, by continually shearing the poloidal component of the settling new horizontal field, the latitudinal differential rotation low in the convection zone generates the next-cycle source-field band poleward of the ongoing-cycle band. The amended scenario is a more-plausible version of Babcock's scenario, and its viability can be explored by appropriate kinematic flux-transport solar-dynamo simulations. A paper giving a full description of our dynamo scenario is posted on arXiv (http://arxiv.org/abs/1606.05371).This work was funded by the Heliophysics Division of NASA's Science Mission Directorate through the Living With a Star Targeted Research and Technology Program and the Hinode

On the relation of Hsub(α) plage brightness variations in solar active regions

International Nuclear Information System (INIS)

Ogir', M.B.

1980-01-01

The variations of hydrogen plage brightnesses in seven spot groups belonging to five active regions are discussed. The observations were made on the Crimean observatory coronograph in 1974 and 1977. The correlation in brightness variations of plages situated in the regions of growing magnetic field was obtained. This was observed in the plages on one spot group as well as in the different groups removing on about 27x10 4 km. In developed groups correlations are mainly seen within a spot group and they are expressed better during flares. The correlations of brightnesses are changing during the active region evolution. Three days observations showed good brightness correlations of all plages in the growing magnetic field region and their decrease that can be explained by the field weakening during natural active region evolution or by the strong flare influence. The existence of the simultaneous variations of brightness in the regions with the growing magnetic field speaks in favour of the simultaneous carring-out of magnetic field or its disturbances into the chromosphere [ru

Prior Flaring as a Complement to Free Magnetic Energy for Forecasting Solar Eruptions

Science.gov (United States)

Falconer, David A.; Moore, Ronald L.; Barghouty, Abdulnasser F.; Khazanov, Igor

2012-01-01

From a large database of (1) 40,000 SOHO/MDI line-of-sight magnetograms covering the passage of 1,300 sunspot active regions across the 30 deg radius central disk of the Sun, (2) a proxy of each active region's free magnetic energy measured from each of the active region's central-disk-passage magnetograms, and (3) each active region's full-disk-passage history of production of major flares and fast coronal mass ejections (CMEs), we find new statistical evidence that (1) there are aspects of an active region's magnetic field other than the free energy that are strong determinants of the active region's productivity of major flares and fast CMEs in the coming few days, (2) an active region's recent productivity of major flares, in addition to reflecting the amount of free energy in the active region, also reflects these other determinants of coming productivity of major eruptions, and (3) consequently, the knowledge of whether an active region has recently had a major flare, used in combination with the active region's free-energy proxy measured from a magnetogram, can greatly alter the forecast chance that the active region will have a major eruption in the next few days after the time of the magnetogram. The active-region magnetic conditions that, in addition to the free energy, are reflected by recent major flaring are presumably the complexity and evolution of the field.

PRIOR FLARING AS A COMPLEMENT TO FREE MAGNETIC ENERGY FOR FORECASTING SOLAR ERUPTIONS

International Nuclear Information System (INIS)

Falconer, David A.; Moore, Ronald L.; Barghouty, Abdulnasser F.; Khazanov, Igor

2012-01-01

From a large database of (1) 40,000 SOHO/MDI line-of-sight magnetograms covering the passage of 1300 sunspot active regions across the 30° radius central disk of the Sun, (2) a proxy of each active region's free magnetic energy measured from each of the active region's central-disk-passage magnetograms, and (3) each active region's full-disk-passage history of production of major flares and fast coronal mass ejections (CMEs), we find new statistical evidence that (1) there are aspects of an active region's magnetic field other than the free energy that are strong determinants of the active region's productivity of major flares and fast CMEs in the coming few days; (2) an active region's recent productivity of major flares, in addition to reflecting the amount of free energy in the active region, also reflects these other determinants of coming productivity of major eruptions; and (3) consequently, the knowledge of whether an active region has recently had a major flare, used in combination with the active region's free-energy proxy measured from a magnetogram, can greatly alter the forecast chance that the active region will have a major eruption in the next few days after the time of the magnetogram. The active-region magnetic conditions that, in addition to the free energy, are reflected by recent major flaring are presumably the complexity and evolution of the field.

Seismo-active faults in the Banat region, Romania

International Nuclear Information System (INIS)

Oros, E.

2002-01-01

The knowledge of the seismo-active faults represents a very important element in every seismic hazard analysis. The main purpose of our paper is to best define the seismo-active faults of the Banat Region. The region is characterized by high seismicity, with important focus of strong earthquakes (I>VII MSK degrees). The quality of the historical data is many times too weak for being used in seismotectonic studies. Thus a correlation between historical and recent seismicity must be done. In our study, several seismic sequences that occurred in the Banat Region, are analysed in detail. The distribution of the epicenters and the correlation tectonics-fault plane solutions reveal important seismotectonic features. The obtained results complete the image of the historical seismicity and offer important information for the future studies of seismic hazard. These results are also very important for the development and configuration of the Banat Seismic Network. The recent seismic activity was analysed for 1995-2002 period, when over 2500 local earthquakes were recorded (M min = 0.5 and M max = 4.8). 26 fault plane solutions were determined (first wave polarities method with additional amplitude constraints). For the earthquakes that occurred at the national border with Yugoslavia and Hungary we used the data from international bulletins. The main seismic sequences were concentrated in seven important zones: Moldova Noua, Herculane Spa - Orsova, Petrosani - Western Jiu Valey, Banloc, Voiteg, Timisoara East and Timisoara North. We also located a small seismic sequence in the Baia de Arama - Tirgu Jiu area. The results were correlated with the faults and major structures, with macroseismic field of the strongest local earthquakes, too. The seismic hazard sources and faults from outside the country (Hungary an Yugoslavia) are pointed out. (authors)

Indian summer monsoon variability during the Holocene as recorded in sediments of the Arabian Sea: Timing and implications

Digital Repository Service at National Institute of Oceanography (India)

Thamban, M.; Kawahata, H.; Rao, V.P.

., 2005). Recently a 11,000 yr reconstruction of sunspots using tree ring ∆ 14 C data revealed exceptional changes in sunspot activity within the Holocene (Solanki et al., 2004). Since sun is the principal source of energy, changes in solar energy output... seem to be stimulated by the sun, suggest- ing the importance of small changes in solar activity lead- ing to perceptible changes in monsoon conditions. Acknowledgements We thank the Directors of National Centre for Ant- arctic and Ocean Research (NCAOR...

Physical activities of students in special primary schools in the central Bohemian region

OpenAIRE

Beznosova, Irina

2011-01-01

1 Abstract Title of the thesis: Physical activities of students in special primary schools in the central Bohemian region Aim of the study: The aim of the thesis is a comprehensive survey of physical activities provided by special primary schools in the Central Bohemian region. Method: We used a method of an empirical research. We studied a representative sample of special primary schools located in the Central Bohemia region in order to ascertain characteristics of the objects of observation...