Kodaikanal digitized white-light data archive (1921–2011): Analysis of various solar cycle features
Sudip Mandal,Manjunath Hegde,Tanmoy Samanta,Gopal Hazra,Gopal Hazra,Dipankar Banerjee,Dipankar Banerjee,B. Ravindra +7 more
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TLDR
In this article, a uniform sunspot area time series along with their positions for a 90-yr period between 1921 and 2011, as obtained from the newly digitized and calibrated white-light images from the Kodaikanal observatory.Abstract:
Context. Long-term sunspot observations are key to understanding and predicting the solar activities and its effects on space weather. Consistent observations, which are crucial for long-term variations studies, are generally not available due to upgradation/modification of observatories over the course of time. We present data for a period of 90 yr acquired from persistent observation at the Kodaikanal observatory in India. Aims. We aim to build a uniform sunspot area time series along with their positions for a 90-yr period between 1921 and 2011, as obtained from the newly digitized and calibrated white-light images from the Kodaikanal observatory. Our aim is to compare this new time series with known sources and confirm some of the earlier reported results with additional new aspects. Methods. We use an advanced semi-automated algorithm to detect the sunspots form each calibrated white-light image. Area, longitude and latitude of each of the detected sunspots are derived. Implementation of a semi-automated method is extremely necessary in such studies as it minimizes the human bias in the detection procedure. Results. Daily, monthly, and yearly sunspot area variations, obtained from the Kodaikanal, compared well with the Greenwich sunspot area data. We find an exponentially decaying distribution for the individual sunspot area for each of the solar cycles. Analyzing the histograms of the latitudinal distribution of the detected sunspots, we find Gaussian distributions, in both the hemispheres, with centers at ~15° latitude. The height of the Gaussian distributions are different for the two hemispheres for a particular cycle. Using our data, we show clear presence of Waldmeier effect, which correlates the rise time with the cycle amplitude. Using the wavelet analysis, we explored different periodicities on different time scales present in the sunspot area times series.read more
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The Transit Light Source Effect: False Spectral Features and Incorrect Densities for M-dwarf Transiting Planets
TL;DR: In this paper, the Max Planck Institute for Astronomy, Heidelberg, Germany and NASA's Science Mission Directorate provided a grant for a study of the effect of solar radiation on the Earth's magnetic field.
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The Transit Light Source Effect. II. The Impact of Stellar Heterogeneity on Transmission Spectra of Planets Orbiting Broadly Sun-like Stars
TL;DR: The National Science Foundation Graduate Research Fellowship Program (DGE-1143953) and NASA's Science Mission Directorate (MSM Directorate) as mentioned in this paper were used for the work of as mentioned in this paper.
Journal ArticleDOI
Analysis of the Hemispheric Sunspot Number Time Series for the Solar Cycles 18 to 24
TL;DR: In this paper, the authors investigate temporal and periodic variations of the hemispheric sunspot number using sunspot data from Kanzelhohe Solar Observatory (KSO) for the time period of 1944 to 2017, which covers Solar Cycles 18 to 23 and almost the entire Solar Cycle 24.
Journal ArticleDOI
The Transit Light Source Effect: False Spectral Features and Incorrect Densities for M-dwarf Transiting Planets
TL;DR: In this paper, spot and faculae covering fractions consistent with observed photometric variabilities for M dwarfs and the associated 0.3-5.5 $\mu$m stellar contamination spectra were modeled.
Journal ArticleDOI
Sunspot area catalogue revisited: Daily cross-calibrated areas since 1874
TL;DR: In this paper, a cross-calibrated and homogeneous record of total daily sunspot areas, both projected and corrected, covering the period between 1874 and 2019 was produced.
References
More filters
Journal ArticleDOI
The empirical mode decomposition and the Hilbert spectrum for nonlinear and non-stationary time series analysis
Norden E. Huang,Zheng Shen,Steven R. Long,Man-Li C. Wu,Hsing H. Shih,Quanan Zheng,Nai-Chyuan Yen,C. C. Tung,Henry H. Liu +8 more
TL;DR: In this paper, a new method for analysing nonlinear and nonstationary data has been developed, which is the key part of the method is the empirical mode decomposition method with which any complicated data set can be decoded.
Journal ArticleDOI
A Practical Guide to Wavelet Analysis.
TL;DR: In this article, a step-by-step guide to wavelet analysis is given, with examples taken from time series of the El Nino-Southern Oscillation (ENSO).
Journal ArticleDOI
The Solar Cycle
TL;DR: An examination of prediction techniques for the solar cycle is examined and a closer look at cycles 23 and 24 is taken.
Journal ArticleDOI
On the 11-Years Cycle of Solar Activity
TL;DR: The shape of the 11-year cycle of solar activity curves depends on the way these processes overlap as mentioned in this paper, which can be found in Figure 1 : The shape of 11-years curves.
Journal ArticleDOI
The 1.3-year and 156-day periodicities in sunspot data: Wavelet analysis suggests a common origin
TL;DR: In this article, a 1.3-year periodicity in the solar rotation rate near the bottom of the solar convec- tion zone was found and significant power at this period (1.28 years) was observed to vary strongly with time.