scholarly journals Large-Scale Patterns of Prominences in the Global Solar Cycles During 1880–1995

1998 ◽  
Vol 167 ◽  
pp. 442-445
Author(s):  
Dirk K. Callebaut ◽  
Valentine I. Makarov ◽  
Ksenia S. Tavastsherna
Keyword(s):  
Large Scale ◽  
Wolf Number ◽  
Solar Cycles ◽  
Zonal Distribution ◽  
Periodic Oscillations ◽  
Period 1880 ◽  
Latitude Distribution ◽  
The Mean ◽  
Long Term Variations

AbstractThe zonal distribution of prominences, their poleward migration from the sunspot zone to the poles, the polar magnetic field reversals and a correlation of the mean latitude of filament bands at minimum activity with the maximum of Wolf number in the next cycle are briefly discussed for the period 1880–1995. The need for research on the longterm latitude distribution of the prominences is emphasized. New results concerning long-term variations of the torsional oscillations of the Sun and quasi-periodic oscillations of the latitude zonal boundaries from an analysis of Hα charts (1915–1990) are given.

scholarly journals The mean tilt of sunspot bipolar regions: theory, simulations and comparison with observations

2020 ◽  
Vol 495 (1) ◽  
pp. 238-248
Author(s):  
N Kleeorin ◽  
N Safiullin ◽  
K Kuzanyan ◽  
I Rogachevskii ◽  
A Tlatov ◽  
...  
Keyword(s):  
Coriolis Force ◽  
Large Scale ◽  
Mean Field ◽  
Wolf Number ◽  
Additional Contribution ◽  
Solar Cycles ◽  
Dynamo Theory ◽  
Large Scale Magnetic Field ◽  
Budget Equation ◽  
The Mean

ABSTRACT A theory of the mean tilt of sunspot bipolar regions (the angle between a line connecting the leading and following sunspots and the solar equator) is developed. A mechanism of formation of the mean tilt is related to the effect of the Coriolis force on meso-scale motions of super-granular convection and large-scale meridional circulation. The balance between the Coriolis force and the Lorentz force (the magnetic tension) determines an additional contribution caused by the large-scale magnetic field to the mean tilt of the sunspot bipolar regions at low latitudes. The latitudinal dependence of the solar differential rotation affects the mean tilt, which can explain deviations from Joy’s law for the sunspot bipolar regions at high latitudes. The theoretical results obtained and the results from numerical simulations based on the non-linear mean-field dynamo theory, which takes into account conservation of the total magnetic helicity and the budget equation for the evolution of the Wolf number density, are in agreement with observational data of the mean tilt of sunspot bipolar regions over individual solar cycles 15–24.

Evolution of Large-Scale Coronal Structures

1994 ◽  
Vol 144 ◽  
pp. 29-33
Author(s):  
P. Ambrož
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Large Scale ◽  
Coronal Magnetic Field ◽  
Source Surface ◽  
Solar Cycles ◽  
Characteristic Relationship ◽  
The Magnetic Field ◽  
Coronal Structures

AbstractThe large-scale coronal structures observed during the sporadically visible solar eclipses were compared with the numerically extrapolated field-line structures of coronal magnetic field. A characteristic relationship between the observed structures of coronal plasma and the magnetic field line configurations was determined. The long-term evolution of large scale coronal structures inferred from photospheric magnetic observations in the course of 11- and 22-year solar cycles is described.Some known parameters, such as the source surface radius, or coronal rotation rate are discussed and actually interpreted. A relation between the large-scale photospheric magnetic field evolution and the coronal structure rearrangement is demonstrated.

scholarly journals The Prognosis and Oncological Predictor of Urachal Carcinoma of the Bladder: A Large Scale Multicenter Cohort Study Analyzed 203 Patients With Long Term Follow-Up

2021 ◽  
Vol 11 ◽  
Author(s):  
Young Dong Yu ◽  
Young Hwii Ko ◽  
Jong Wook Kim ◽  
Seung Il Jung ◽  
Seok Ho Kang ◽  
...  
Keyword(s):  
Large Scale ◽  
Survival Rates ◽  
Stage Iii ◽  
Pathological Stage ◽  
Urachal Carcinoma ◽  
Multicenter Cohort ◽  
Long Term Follow Up ◽  
The Mean

AimThis study evaluated the prognosis and survival predictors for bladder urachal carcinoma (UC), based on large scale multicenter cohort with long term follow-up database.MethodsA total 203 patients with bladder UC treated at 19 hospitals were enrolled. Clinical parameters on carcinoma presentation, diagnosis, and therapeutic methods were reviewed for the primary cancer and for all subsequent recurrences. The stage of UC was stratified by Mayo and Sheldon pathological staging system. Oncological outcomes and the possible clinicopathological parameters associated with survival outcomes were investigated.ResultsThe mean age of the patients was 54.2 years. Among the total of 203 patients, stages I, II, III, and IV (Mayo stage) were 48 (23.8%), 108 (53.5%), 23 (11.4%), and 23 (11.4%), respectively. Gross hematuria and bladder irritation symptoms were the two most common initial symptoms. The mean follow-up period was 65 months, and 5-year overall survival rates (OS), cancer-specific survival rates (CSS), and recurrence-free survival rates (RFS) were 88.3, 83.1, and 63.9%, respectively. For the patients with Mayo stage ≥III, OS, CSS, and RFS were significantly decreased to 38.0, 35.2, and 28.4%, respectively. The higher pathological stage (Mayo stage ≥III, Sheldon stage ≥IIIc), positive surgical margin (PSM), and positive lymphovascular invasion (PLM) were independent predictors of shorter OS, CSS, and RFS.ConclusionThe pathological stage, PSM, and PLM were significantly associated with the survival of UC patients, emphasizing an importance of the complete surgical resection of tumor lesion.

VARIATIONS IN THE KARA SEA LEVEL, THEIR STERIC FACTORS, AND SOLAR RADIATION DURING 1993-2018

2021 ◽  
pp. 38-52
Author(s):  
A.V. KHOLOPTSEV ◽  
◽  
S.A. PODPORIN ◽  
V.A. SAFONOV ◽  
◽  
...  
Keyword(s):  
Solar Radiation ◽  
Sea Level ◽  
Water Layer ◽  
Kara Sea ◽  
Mean Values ◽  
Mean Intensity ◽  
Steric Factors ◽  
The Mean ◽  
Long Term Variations

The GLORYS12v.1 and ERA5 reanalyses for different months are used to study a relationship between long-term variations in the monthly mean values of sea level in different areas of the Kara Sea and their steric factors during 1993-2018. The areas of the sea were identified where the relationships between these changes and variations in the mean temperature and salinity of the upper quasihomogeneous water layer, as well as the variations in the monthly mean intensity of their insolation, are statistically significant.

scholarly journals Large scale magnetic helicity fluxes estimated from MDI magnetic synoptic charts

2012 ◽  
Vol 8 (S294) ◽  
pp. 157-158
Author(s):  
Shangbin Yang ◽  
Hongqi Zhang
Keyword(s):  
Solar Cycle ◽  
Magnetic Flux ◽  
Solar Disk ◽  
Large Scale ◽  
Magnetic Helicity ◽  
Local Correlation ◽  
Solar Cycles ◽  
23Rd Solar Cycle ◽  
Term Evolution

AbstractTo investigate the characteristics of large scale and long term evolution of magnetic helicity with solar cycles, we use the method of Local Correlation Tracking (LCT) to estimate the magnetic helicity evolution over the 23rd solar cycle from 1996 to 2009 by using 795 MDI magnetic synoptic charts. The main results are: the hemispheric helicity rule still holds in general, i.e. the large-scale negative (positive) magnetic helicity dominates the northern (southern) hemisphere. However, the large scale magnetic helicity fluxes show the same sign in both hemispheres around 2001 and 2005. The global, large scale magnetic helicity flux over the solar disk changes from negative value at the beginning of the 23rd solar cycle to positive value at the end of the cycle, which also shows the similar trend from the normalized magnetic flux by using the magnetic flux. The net accumulated magnetic helicity is negative in the period between 1996 and 2009.

scholarly journals Long-term studies of MLT summer length definitions based on mean zonal wind features observed for more than one solar cycle at mid- and high-latitudes in the northern hemisphere

2021 ◽  
Author(s):  
Juliana Jaen ◽  
Toralf Renkwitz ◽  
Jorge L. Chau ◽  
Maosheng He ◽  
Peter Hoffmann ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Zonal Wind ◽  
Large Scale ◽  
Southern Oscillation ◽  
Lower Thermosphere ◽  
Polar Vortex ◽  
Mean Value ◽  
High Latitudes ◽  
The Mean

Abstract. Specular meteor radars (SMRs) and partial reflection radars (PRRs) have been observing mesospheric winds for more than a solar cycle over Germany (~54 °N) and northern Norway (~69 °N). This work investigates the mesospheric mean zonal wind and the zonal mean geostrophic zonal wind from the Microwave Limb Sounder (MLS) over these two regions between 2004 and 2020. Our study focuses on the summer when strong planetary waves are absent and the stratospheric and tropospheric conditions are relatively stable. We establish two definitions of the summer length according to the zonal wind reversals: (1) the mesosphere and lower thermosphere summer length (MLT-SL) using SMR and PRR winds, and (2) the mesosphere summer length (M-SL) using PRR and MLS. Under both definitions, the summer begins around April and ends around mid-September. The largest year to year variability is found in the summer beginning in both definitions, particularly at high-latitudes, possibly due to the influence of the polar vortex. At high-latitudes, the year 2004 has a longer summer length compared to the mean value for MLT-SL, as well as 2012 for both definitions. The M-SL exhibits an increasing trend over the years, while MLT-SL does not have a well-defined trend. We explore a possible influence of solar activity, as well as large-scale atmospheric influences (e.g. quasi-biennial oscillations (QBO), El Niño-southern oscillation (ENSO), major sudden stratospheric warming events). We complement our work with an extended time series of 31 years at mid-latitudes using only PRR winds. In this case, the summer length shows a breakpoint, suggesting a non-uniform trend, and periods similar to those known for ENSO and QBO.

scholarly journals The Hα Emitting Regions of the Accretion Disks in Algols

1989 ◽  
Vol 107 ◽  
pp. 9-22
Author(s):  
G. J. Peters
Keyword(s):  
Accretion Disk ◽  
Accretion Disks ◽  
High Dispersion ◽  
Day Range ◽  
Dispersion Data ◽  
Mass Outflow ◽  
The Mean ◽  
Size Asymmetry ◽  
Long Term Variations

AbstractThe circumstellar plasma that produces Hα emission in Algol binaries has been investigated using phase-resolved, high dispersion data acquired from CCD and image tube detectors. Results are summarized in this paper, including discussions of the disk geometry and size, asymmetry in the distribution of material, long-term or non-phase dependent variability, mass outflow, the mean electron density, and how the latter properties vary with the system’s period or location in the r - q diagram. Five systems which display permanent emission with periods ranging from 4.5 to 261 days (SW Cyg, UX Mon, TT Hya, AD Her, and RZ Oph) are intercompared. If P < 4.5 days, no permanent disks are observed, while if P > 6 days, stable disks with only slight long-term variations in their Hα brightness are seen. The most variable systems appear to be those in the 5 - 6 day range, but the star’s position in the r - q diagram has the largest influence on its behavior. The trailing side of the accretion disk, where the gas stream impacts the inner disk, is usually brighter, and the leading side is often times more extended. The disk extends out to at least 95%of the Roche surface of the primary and is highly flattened (≤Rp). Mass outflow near phase 0.5 is commonplace.

scholarly journals Metals Leak from Tilled Soil in a Century – A Review

2015 ◽  
Vol 7 (12) ◽  
pp. 15
Author(s):  
Gunnar Bengtsson
Keyword(s):  
Large Scale ◽  
Penetration Rate ◽  
Modern Society ◽  
Field Studies ◽  
Basic Set ◽  
Metal Contents ◽  
Significant Difference ◽  
Supplementary Material ◽  
The Mean

<p>Toxic metals are mobilized on a large scale in modern society. Many of those metals end up in sewage sludge. The objective of this review was to elucidate the threat to groundwater due to a few metals lost from tilled sludge amended soils. It is sometimes suggested that these metals are immobilized in the topsoil and do not move downward. In contrast, dozens of long term field studies around the world indicate that penetration depths for metals increase with time since deposition.</p><p>Such studies were examined in depth in the current analysis. An equation was developed for calculation of long term mean metal penetration rates into the topsoil for copper and silver. The equation is valid for about a century but not much longer. The mean depths of a basic set of 11 cases from studies over 4 years to 100 years were predicted with a standard deviation of 11%. A typical penetration rate was 3 mm per year. There was no significant difference in penetration rate between several cations. Extremely large amendments were associated with larger penetration rates.</p><p>When metals have traversed the topsoil, the groundwater will be contaminated. The European Groundwater Pollution Directive stipulates that pesticide levels should be kept below 0.1 µg/l. When sludge is applied to agricultural soil, this level may by far be exceeded for many metals, even if strict limitations are applied to the metal contents of the sludge. This calls for careful assessment of the groundwater consequences of sludge amendment.</p><p>Extensive supplementary material provides many detailed tables, texts and references.</p>

scholarly journals Measuring stellar magnetic helicity density

2020 ◽  
Vol 493 (1) ◽  
pp. 1003-1012
Author(s):  
K Lund ◽  
M Jardine ◽  
L T Lehmann ◽  
D H Mackay ◽  
V See ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Magnetic Energy ◽  
Fundamental Property ◽  
Mass Range ◽  
Doppler Imaging ◽  
Magnetic Flux Density ◽  
Rossby Number ◽  
Solar Cycles ◽  
The Mean

ABSTRACT Helicity is a fundamental property of a magnetic field but to date it has only been possible to observe its evolution in one star – the Sun. In this paper, we provide a simple technique for mapping the large-scale helicity density across the surface of any star using only observable quantities: the poloidal and toroidal magnetic field components (which can be determined from Zeeman–Doppler imaging) and the stellar radius. We use a sample of 51 stars across a mass range of 0.1–1.34 M⊙ to show how the helicity density relates to stellar mass, Rossby number, magnetic energy, and age. We find that the large-scale helicity density increases with decreasing Rossby number Ro, peaking at Ro ≃ 0.1, with a saturation or decrease below that. For both fully and partially convective stars, we find that the mean absolute helicity density scales with the mean squared toroidal magnetic flux density according to the power law: $|\langle {h\, }\rangle |$ ∝ $\langle {\rm {{\it B}_{tor}}^2_{}\, \rangle }^{0.86\, \pm \, 0.04}$. The scatter in this relation is consistent with the variation across a solar cycle, which we compute using simulations and observations across solar cycles 23 and 24, respectively. We find a significant decrease in helicity density with age.

The cause of the appearance or disappearance of the Rieger-type periodicity in the northern and southern hemispheres of the sun

2021 ◽  
Vol 38 ◽  
Author(s):  
N. B. Xiang ◽  
X. H. Zhao ◽  
F. Y. Li
Keyword(s):  
Solar Cycle ◽  
Sunspot Area ◽  
Solar Cycles ◽  
Sunspot Maximum ◽  
Royal Observatory ◽  
Rotation Parameters ◽  
The Mean ◽  
Two Parameters ◽  
Northern And Southern Hemispheres

Abstract We use a continuous wavelet transform to analyse the daily hemispheric sunspot area data from the Greenwich Royal Observatory during cycles 12–24 and then study the cause of the appearance or disappearance of the Rieger-type periodicity in the northern and southern hemispheres during a certain cycle. The Rieger-type periodicity in the northern and southern hemispheres should be developed independently in the two hemispheres. This periodicity in the northern hemisphere is generally anti-correlated with the long-term variations in the mean solar cycle strength of hemispheric activity, but the correlation of the two parameters in the southern hemisphere shows a weak correlation. The appearance or disappearance of Rieger-type periodicity in the northern and southern hemispheres during a certain solar cycle is not directly correlated with their corresponding hemispheric mean activity strength but should be related to the strength of the hemispheric activity during sunspot maximum times, which hints the Rieger-type periodicity is more related to temporal evolution of toroidal magnetic field. The Rieger-type periodicity in the two hemispheres disappears in those solar cycles with relatively weak hemispheric activity during sunspot maximum times. The reason for the disappearance of this periodicity may be due to the combined influence of relatively weak toroidal magnetic fields and torsional oscillations, the differential rotation parameters vary through the solar cycle and may not remain more or less unchanged during some time, which does not permit the strong growth of magnetic Rossby waves.

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