scholarly journals Constraints on long-term changes in solar activity from the range of variability of cosmogenic radionuclide records

2011 ◽  
Vol 7 (3) ◽  
pp. 355-364 ◽  
Author(s):  
R. Muscheler ◽  
U. Heikkilä
Keyword(s):  
Solar Activity ◽  
Long Term Changes ◽  
Cosmogenic Radionuclide

scholarly journals Ca II K spectroheliograms for studies of long-term changes in solar irradiance

2018 ◽  
Vol 13 (S340) ◽  
pp. 125-128 ◽  
Author(s):  
Theodosios Chatzistergos ◽  
Ilaria Ermolli ◽  
Natalie A. Krivova ◽  
Sami K. Solanki
Keyword(s):  
Solar Activity ◽  
Solar Irradiance ◽  
Long Term Changes

AbstractWe address the importance of historical full-disc Ca II K spectroheliograms for solar activity and irradiance reconstruction studies. We review our work on processing such data to enable them to be used in irradiance reconstructions. We also present our preliminary estimates of the plage areas from five of the longest available historical Ca II K archives.

scholarly journals Long-term trends in the relation between daytime and nighttime values of <I>fo</I>F2

2008 ◽  
Vol 26 (5) ◽  
pp. 1199-1206 ◽  
Author(s):  
A. D. Danilov
Keyword(s):  
Solar Activity ◽  
Term Trend ◽  
The World ◽  
Long Term Changes ◽  
Long Term Trends ◽  
Thermospheric Winds ◽  
Long Term Trend ◽  
Ionospheric Sounding ◽  
Limiting Value

Abstract. The data from the vertical ionospheric sounding for 12 stations over the world were analyzed to find the relation between the values of foF2 for 02:00 LT and 14:00 LT of the same day. It is found that, in general, there exists a negative correlation between foF2(02) and foF2(14). The value of the correlation coefficient R(foF2) can be in some cases high enough and reach minus 0.7–0.8. The value of R(foF2) demonstrates a well pronounced seasonal variations, the highest negative values being observed at the equinox periods of the year. It is also found that R(foF2) depends on geomagnetic activity: the magnitude of R(foF2) is the highest for the choice of only magnetically quiet days (Ap<6), decreasing with the increase of the limiting value of Ap. For a fixed limitation on Ap, the value of R(foF2) depends also on solar activity. Apparently, the effects found are related to thermospheric winds. Analysis of long series of the vertical sounding data shows that there is a long-term trend in R(foF2) with a statistically significant increase in the R(foF2) magnitude after about 1980. Similar analysis is performed for the foF2(02)/foF2(14) ratio itself. The ratio also demonstrates a systematic trend after 1980. Both trends are interpreted in terms of long-term changes in thermospheric circulation.

scholarly journals Nitrate Fluctuations in Antarctic Snow and Firn: Potential Sources and Mechanisms of Formation

1982 ◽  
Vol 3 ◽  
pp. 243-248 ◽  
Author(s):  
Bruce C. Parker ◽  
Edward J. Zeller ◽  
Anthony J. Gow
Keyword(s):  
Solar Activity ◽  
Upper Atmosphere ◽  
South Pole ◽  
Ion Concentrations ◽  
Potential Sources ◽  
Long Term Changes ◽  
Antarctic Snow ◽  
Mechanisms Of Formation

We summarize here data on in situ nitrate ion concentrations in snow pits and firn cores over the last ∼3 250 a. Nitrate fluctuations show seasonal, 11 and 22 a periodicities, and long-term changes both at South Pole station and Vostok. High nitrate levels conform to winter darkness and solar activity peaks. Long-term lows and highs conform to solar activity minima and maxima. The data available support the hypothesis that nitrate is fixed in the upper atmosphere by some solar-mediated phenomenon causing a periodicity in East Antarctica snow. Background levels and non-periodic spikes in nitrate come from other sources.

scholarly journals New evidence of the Suess/de Vries cycle existing in historical naked-eye observations of sunspots

2020 ◽  
Vol 29 (1) ◽  
pp. 28-31
Author(s):  
Lihua Ma ◽  
José M. Vaquero
Keyword(s):  
Solar Activity ◽  
Earth Science ◽  
Historical Documents ◽  
Naked Eye ◽  
Long Term Changes ◽  
De Vries ◽  
Signal Changes ◽  
New Evidence ◽  
Sunspot Series

AbstractSolar activity affects geophysical and heliophysical processes. Long-term changes in solar activity are closely related to climate change. Solar physicists and earth science researchers need longer observations of solar activity. Current continuous observations of solar activity are only about 400 years. Some scholars have compiled naked-eye observations of sunspots from 200 BC to 1918 AD from historical documents. In this present work, the authors use the weighted wavelet transform to study the observations series. The results show the Suess - de Vries cycle with a period from 195- to 235-year existing in the discontinuous sunspot series. Meanwhile, the cycle signal changes with time. Especially, the Suess/de Vries cycle is relatively obvious from 200 BC to 400 AD, 800 AD to 1340 AD, 1610 AD to 1918 AD, with a period of about 211-year, about 195-year, and about 235-year, respectively.

New Data about Long-Term Changes of Solar Activity

2018 ◽  
Vol 58 (8) ◽  
pp. 1057-1060
Author(s):  
V. M. Efimenko ◽  
V. G. Lozitsky
Keyword(s):  
Solar Activity ◽  
Long Term Changes

Dependence of foF2 long-term changes on solar activity and longitude

2001 ◽  
Vol 28 (7) ◽  
pp. 1017-1022 ◽  
Author(s):  
A.V. Garbatsevich ◽  
M.G. Deminov ◽  
R.G. Deminov ◽  
Yu.S. Sitnov
Keyword(s):  
Solar Activity ◽  
Long Term Changes

scholarly journals Nitrate Fluctuations in Antarctic Snow and Firn: Potential Sources and Mechanisms of Formation

1982 ◽  
Vol 3 ◽  
pp. 243-248 ◽  
Author(s):  
Bruce C. Parker ◽  
Edward J. Zeller ◽  
Anthony J. Gow
Keyword(s):  
Solar Activity ◽  
Upper Atmosphere ◽  
South Pole ◽  
Ion Concentrations ◽  
Potential Sources ◽  
Long Term Changes ◽  
Antarctic Snow ◽  
Mechanisms Of Formation

We summarize here data on in situ nitrate ion concentrations in snow pits and firn cores over the last ∼3 250 a. Nitrate fluctuations show seasonal, 11 and 22 a periodicities, and long-term changes both at South Pole station and Vostok. High nitrate levels conform to winter darkness and solar activity peaks. Long-term lows and highs conform to solar activity minima and maxima. The data available support the hypothesis that nitrate is fixed in the upper atmosphere by some solar-mediated phenomenon causing a periodicity in East Antarctica snow. Background levels and non-periodic spikes in nitrate come from other sources.

scholarly journals VIRGO Radiometry and Total Solar Irradiance 1996–2000 Revised

2001 ◽  
Vol 203 ◽  
pp. 105-110 ◽  
Author(s):  
C. Fröhlich ◽  
W. Finsterle
Keyword(s):  
Solar Activity ◽  
Solar Irradiance ◽  
Solar Maximum ◽  
Total Solar Irradiance ◽  
Minimum Period ◽  
Long Term Changes ◽  
Early Increase ◽  
Solar Uv ◽  
Dependent Behaviour

The long-term changes of the VIRGO radiometers have been re-analyzed in detail in order to resolve the puzzle of the early increase of the total solar irradiance (TSI) as observed by VIRGO. The exposure dependent changes can be described by a model which is based on a combination of an early increase of the sensitivity and a degradation with time which is modulated by the dose of solar UV radiation each detector receives. After correcting for the exposure-dependent behaviour both operational radiometers show an increase of their sensitivity which depends only on the time they are switched-on. After removing this increase the VIRGO TSI remains more or less constant during the minimum period of solar activity and reaches the solar maximum at levels comparable to the ones of former maxima.

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