Long-term variations in meridional motion of sunspot groups: comparison of DPD and SOON data

2018 ◽  
Vol 13 (S340) ◽  
pp. 51-52
Author(s):  
J. Javaraiah
Keyword(s):  
Solar Cycle ◽  
Sunspot Group ◽  
Group Data ◽  
Solar Cycle 23 ◽  
Meridional Motion ◽  
The Mean ◽  
Long Term Variations ◽  
Sunspot Groups

AbstractWe have analyzed the Debrecen Photoheliographic Data (DPD) and the Solar Optical Observing Network (SOON) sunspot group data during the period 1977 – 2015 and find that during the maximum of solar cycle 23 there is a large difference in the mean meridional motion of sunspot groups determined from DPD and SOON data.

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 Persistent Active Longitudes in Sunspot Activity: Sun-as-a-Star Approach

2004 ◽  
Vol 219 ◽  
pp. 128-132
Author(s):  
S. V. Berdyugina ◽  
I. G. Usoskin
Keyword(s):  
Sunspot Group ◽  
Active Regions ◽  
Magnetic Activity ◽  
Sunspot Activity ◽  
Flip Flop ◽  
The Past ◽  
Highly Active ◽  
Group Data ◽  
Cool Stars ◽  
The Mean

Using a new Sun-as-a-star approach we analyze sunspot group data for the past 120 years and reveal that sunspots are formed preferably in two persistent migrating active longitudes 180° apart. Their migration is determined by changes of the mean latitude of sunspots and the surface differential rotation. The two active regions periodically alternate being the dominant region with a period of about 3.7 years similar to the “flip-flop” phenomenon known in starspot activity. The fact that the Sun shows the same pattern of magnetic activity as highly active stars strengthens the solar paradigm for magnetic activity on cool stars.

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 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.

Number of Sunspot Groups and Individual Sunspots Recorded by Tevel for the Period 1816–1836 in the Dalton Minimum

2021 ◽  
Vol 922 (1) ◽  
pp. 58
Author(s):  
V. M. S. Carrasco
Keyword(s):  
Solar Cycle ◽  
Sunspot Number ◽  
Sunspot Group ◽  
Maunder Minimum ◽  
The Other ◽  
Solar Cycles ◽  
Group Number ◽  
The One ◽  
Dalton Minimum ◽  
Sunspot Groups

Abstract Cornelis Tevel made sunspot observations during the period 1816–1836, including the Dalton Minimum. In this work, the first revision of these observations since Wolf incorporated them into his database is presented. On the one hand, the number of individual sunspots from Tevel’s drawings was counted. This is of special interest for the sunspot number reconstruction because this kind of information is not as common in historical sunspot records as the number of groups. Thus, Tevel could be considered for the future reconstruction of the sunspot number index. On the other hand, the number of groups counted according to modern sunspot group classifications finding significant misinterpretations with the number of groups assigned to Tevel in the existing databases. Tevel was a relevant sunspot observer in the Dalton Minimum. In fact, he was the observer with the highest number of groups observed in Solar Cycles 6 and 7 according to the existing sunspot group number databases. According to the raw group number recount in this work, the maximum amplitudes for Solar Cycles 6 and 7 are, respectively, 27% and 7% lower than those previously determined. Moreover, Solar Cycle 6 is the weakest solar cycle since the Maunder Minimum after applying these new counts. Group counts from Tevel’s observations were compared with those from relevant contemporary astronomers, demonstrating that Schwabe and Tevel systematically recorded a higher number of groups than Flaugergues and Derfflinger. In addition, sunspot areas and positions recorded by Tevel should be used with caution for scientific purposes.

Variation of the meteor count rate and echo height during solar cycle 23 and 24

2018 ◽  
Vol 13 (S340) ◽  
pp. 73-74
Author(s):  
B. Premkumar ◽  
K. Chenna Reddy ◽  
G. Yellaiah
Keyword(s):  
Solar Cycle ◽  
Count Rate ◽  
Lower Thermosphere ◽  
Radar Data ◽  
Neutral Atmosphere ◽  
Meteor Radar ◽  
Solar Cycle 23 ◽  
Cycle 24 ◽  
Good Agreement

AbstractThe meteoroid ablation is an important source of upper atmosphere metal atoms. Many meteoroids ablate between 70 - 110 km and form an ionized plasma trail which is detected by radar technique. It is also known that the ablation heights of the meteors depend on various factors such as velocity, mass, and its composition, etc. The meteor ablation height provides new opportunities to gather information on the neutral atmosphere in the Mesosphere and Lower Thermosphere (MLT) region. In this study, we analysed the 11 years of meteor radar data (2005 - 2015), i.e., descending phase of solar cycle 23, and ascending phase of solar cycle 24, detected by all sky meteor radar at Thumba. We found that the solar activity influences the meteor ablation height, here, during the solar maxima meteor peak detection height rise to few hundred meters higher altitudes. We also examined the long term pattern of the meteor count rate which shows a decreasing trend and has good agreement with the sunspot number (SSN).

Solar cycle and global long term variations of stratospheric ozone

1999 ◽  
Vol 24 (5) ◽  
pp. 665-669 ◽  
Author(s):  
I.M. Martin ◽  
T. Toroshelidze ◽  
W.E. Alves ◽  
M.G.S. Mello ◽  
A.A. Gusev ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Stratospheric Ozone ◽  
Long Term Variations
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