Extending the sunspot area series from Kodaikanal Solar Observatory

Jha, Bibhuti Kumar; Hegde, Manjunath; Priyadarshi, Aditya; Mandal, Sudip; Ravindra, B.; Banerjee, D.

doi:10.3389/fspas.2022.1019751

Cited by 11 publications

(7 citation statements)

References 31 publications

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“…The state-of-the-art techniques has been developed to detect the sunspot (Ravindra et al 2013;Mandal et al 2017;Jha et al 2022), sunspot umbra (Jha et al 2019), plages (Chatterjee et al 2016), filaments (Chatterjee et al 2017) and Ca-K prominence (Chatterjee et al 2020) from these data sets. The latitude-time plot for all these data sets are shown in Figure 2a (sunspot), 2b (plages), 2c (filaments) and 2d (Ca-k prominences).…”

Section: A Few Results From Koso Digital Archivementioning

confidence: 99%

Long-term Evolution of Magnetic Field Proxies as Deduced from Archival Data

Banerjee,

Jha,

Mandal

et al. 2022

Proc. IAU

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Regular observations of the solar magnetic field are available only for about the last five cycles. Thus, to understand the origin of the variation of the solar magnetic field, it is essential to reconstruct the magnetic field for the past cycles, utilizing the proxies of the magnetic field from other data sets. Long-term uniform observations for the past 100 yrs, as recorded at the Kodaikanal Solar Observatory (KoSO), in multi-wavelengths provide such an opportunity. Various automatic techniques have been developed to extract these features from KoSO data. We analyzed the properties of these extracted features to understand global solar magnetism in the past.

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Section: A Few Results From Koso Digital Archivementioning

confidence: 99%

Long-term Evolution of Magnetic Field Proxies as Deduced from Archival Data

Banerjee,

Jha,

Mandal

et al. 2022

Proc. IAU

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“…For example, clear signatures of equatorward and poleward migration of filaments are seen during the beginning the cycles. Furthermore, the equatorward branches are observed to be spread over a larger band of latitude as compared to the sunspots (Mandal et al 2017;Jha et al 2022). These findings are consistent with ones found previously with digitized H α and Ca K photographic plates of KoSO (Chatterjee et al 2017(Chatterjee et al , 2020.…”

Section: Statistical Properties: Time-latitude Diagrammentioning

confidence: 97%

Detection of Solar Filaments Using Suncharts from Kodaikanal Solar Observatory Archive Employing a Clustering Approach

Priyadarshi

Hegde

Jha

et al. 2023

ApJ

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With over 100 yr of solar observations, the Kodaikanal Solar Observatory (KoSO) is a one-of-a-kind solar data repository in the world. Among its many data catalogs, the “suncharts” at KoSO are of particular interest. These suncharts (1904–2020) are colored drawings of different solar features, such as sunspots, plages, filaments, and prominences, made on papers with a Stonyhurst latitude–longitude grid etched on them. In this paper, we analyze this unique data by first digitizing each sunchart using an industry-standard scanner and saving those digital images in a high-resolution “.tif” format. We then examine cycle 19 and cycle 20 data (two of the strongest cycles of the last century) with the aim of detecting filaments. To this end, we employed the “K-means clustering” method, and obtained different filament parameters such as position, tilt angle, length, and area. Our results show that filament length (and area) increases with latitude and the poleward migration is clearly dominated by a particular tilt sign. Lastly, we cross verified our findings with results from KoSO digitized photographic plate database for the overlapping time period and obtained a good agreement between them. This work, acting as a proof-of-the-concept, will kickstart new efforts to effectively use the entire hand-drawn series of multifeature, full-disk solar data and enable researchers to extract new sciences, such as the generation of pseudomagnetograms for the last 100 yr.

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“…Please note that since the intermediate CMEs cannot strictly be considered as either fast or slow CMEs, and since, in this work, we are more interested in the slow and fast CMEs, we will not be including the intermediate CMEs in the analysis. In Table 1, we have grouped the yearly studied CMEs into different subclasses, according to the phase of the solar cycle that the considered years correspond to (see Hathaway 2015;Jha et al 2022). It should be noted here that we tried to be unbiased with the selection and hence the contribution of any particular category of CMEs under consideration, by studying CMEs that occurred during different phases of cycles 23 and 24.…”

Section: Yearly Occurrencementioning

confidence: 99%

A Coronal Mass Ejection Source Region Catalog and Their Associated Properties

Majumdar,

Patel,

Pant

et al. 2023

ApJS

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The primary objective of this study is to connect coronal mass ejections (CMEs) to their source regions, primarily to create a CME source region catalog, and secondarily to probe the influence that the source regions have on the different statistical properties of CMEs. We create a source region catalog for 3327 CMEs from 1998 to 2017, thus capturing the different phases of cycles 23 and 24. The identified source regions are segregated into three classes—active regions, prominence eruptions, and active prominences—while the CMEs are segregated into slow and fast groups, based on their average projected speeds. We find the contributions of these three source region types to the occurrences of slow and fast CMEs to be different in the above period. A study of the distribution of the average speeds reveals different power laws for CMEs originating from different sources, and the power laws are different during the different phases of cycles 23 and 24. A study of the statistical latitudinal deflections shows equatorward deflections, while the magnitudes of the deflections again bear imprints of the source regions. An east–west asymmetry is also noted, particularly in the rising phase of cycle 23, with the presence of active longitudes for the CMEs, with a preference toward the western part of the Sun. Our results show that different aspects of CME kinematics bear strong imprints of the source regions they originate from, thus indicating the existence of different ejection and/or propagation mechanisms of these CMEs.

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Extending the sunspot area series from Kodaikanal Solar Observatory

Cited by 11 publications

References 31 publications

Long-term Evolution of Magnetic Field Proxies as Deduced from Archival Data

Long-term Evolution of Magnetic Field Proxies as Deduced from Archival Data

Detection of Solar Filaments Using Suncharts from Kodaikanal Solar Observatory Archive Employing a Clustering Approach

A Coronal Mass Ejection Source Region Catalog and Their Associated Properties

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