scholarly journals The potential of Ca II K observations for solar activity and variability studies

2018 ◽  
Vol 13 (S340) ◽  
pp. 115-120 ◽  
Author(s):  
Ilaria Ermolli ◽  
Theodosios Chatzistergos ◽  
Natalie A. Krivova ◽  
Sami K. Solanki
Keyword(s):  
Magnetic Field ◽  
Time Series ◽  
Solar Activity ◽  
Solar Atmosphere ◽  
Narrow Band ◽  
Long Term Variations

AbstractSeveral observatories around the globe started regular full-disc imaging of the solar atmosphere in the Ca II K line in the early decades of the 20th century. These observations are continued today at a few sites with either old spectroheliographs or modern telescopes equipped with narrow-band filters. The Ca II K time series are unique in representing long-term variations of the Sun’s chromospheric magnetic field. However, meaningful results from their analysis require accurate processing of the available data and robust merging of the information stored in different archives. This paper provides an overview of the historical and modern full-disc Ca II K observations, with focus on their quality and the main results obtained from their analysis over the last decade.

Application of singular spectrum analysis in reconstruction of the annual signal from GRACE

2020 ◽  
Vol 14 (3) ◽  
pp. 295-302
Author(s):  
Chuandong Zhu ◽  
Wei Zhan ◽  
Jinzhao Liu ◽  
Ming Chen
Keyword(s):  
Time Series ◽  
Spectrum Analysis ◽  
Singular Spectrum Analysis ◽  
Mixture Effect ◽  
Singular Spectrum ◽  
Grace Data ◽  
Terrestrial Water ◽  
Annual Signal ◽  
Long Term Variations

AbstractThe mixture effect of the long-term variations is a main challenge in single channel singular spectrum analysis (SSA) for the reconstruction of the annual signal from GRACE data. In this paper, a nonlinear long-term variations deduction method is used to improve the accuracy of annual signal reconstructed from GRACE data using SSA. Our method can identify and eliminate the nonlinear long-term variations of the equivalent water height time series recovered from GRACE. Therefore the mixture effect of the long-term variations can be avoided in the annual modes of SSA. For the global terrestrial water recovered from GRACE, the peak to peak value of the annual signal is between 1.4 cm and 126.9 cm, with an average of 11.7 cm. After the long-term and the annual term have been deducted, the standard deviation of residual time series is between 0.9 cm and 9.9 cm, with an average of 2.1 cm. Compared with the traditional least squares fitting method, our method can reflect the dynamic change of the annual signal in global terrestrial water, more accurately with an uncertainty of between 0.3 cm and 2.9 cm.

Search for long term variations of the interplanetary magnetic field

Solar Physics ◽  
1975 ◽  
Vol 45 (1) ◽  
pp. 241-254 ◽  
Author(s):  
F. Mariani ◽  
L. Diodato ◽  
G. Moreno
Keyword(s):  
Magnetic Field ◽  
Interplanetary Magnetic Field ◽  
Long Term Variations

scholarly journals Solar Modulation Effects in Terrestrial Production of Carbon-14

Radiocarbon ◽  
1980 ◽  
Vol 22 (2) ◽  
pp. 133-158 ◽  
Author(s):  
Giuliana Castagnoli ◽  
Devendra Lal
Keyword(s):  
Solar Activity ◽  
Cosmic Ray ◽  
Solar Modulation ◽  
Carbon 14 ◽  
Cosmic Ray Modulation ◽  
The Earth ◽  
Secular Variations ◽  
Galactic Cosmic Ray ◽  
Long Term Variations

This paper is concerned with the expected deviations in the production rate of natural 14C on the earth due to changes in solar activity. We review the published estimates of the global production rates of 14C due to galactic and solar cosmic ray particles, and present new estimates of the expected secular variations in 14C production, taking into account the latest information available on galactic cosmic ray modulation and long-term variations in solar activity.

scholarly journals Wavelet analysis of long-term variations in neutron monitor, sunspot number and interplanetary magnetic field data

2021 ◽  
pp. 39-42
Author(s):  
Fraser Baird ◽  
Alexander MacKinnon
Keyword(s):  
Magnetic Field ◽  
Field Data ◽  
Solar Magnetic Field ◽  
Cosmic Ray ◽  
Negative Polarity ◽  
Neutron Monitors ◽  
Magnetic Field Data ◽  
First Time ◽  
Long Term Variations

For the first time, based on the experimental data of AMS-02, a three-parameter spectrum of variations of ga - lactic cosmic rays was obtained in the range of rigidity 1- 20 GV, to which neutron monitors are most sensitive. It was found that during the period of negative polarity of the solar magnetic field, a power-law spectrum of va - riations is observed with a strong exponential decay in the region of high rigidity. When the polarity changes to positive at the beginning of the new 24th solar cycle, the spectrum of cosmic ray variations becomes purely po- wer-law. The transition to the experimentally obtained spectrum of variations will make it possible to remove a number of uncertainties and increase the accuracy of the analysis of data from the ground network of detectors. This will make it possible to retrospectively obtain fluxes of galactic protons with an average monthly resolution for the period of the space era based on ground-based monitoring.

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