Chinese Sunspot Drawings and Their Digitization—(VII) Sunspot Penumbra to Umbra Area Ratio Using the Hand-Drawing Records from Yunnan Observatories

Hou, Jiawei; Zeng, Shu-Guang; Zheng, Shibao; Luo, Xiaoyu; Deng, Linhua; Li, Yangyang; Chen, Yanqing; Ge, Lin; Feng, Yongli; Tao, Jing

doi:10.1088/1674-4527/ac7f87

Cited by 6 publications

(3 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…And indeed, we find that although the absolute value of q is slightly less than that of KoSO, the trend remains similar in both the data sets. Furthermore, Carrasco et al (2018), and recently Hou et al (2022) (including all spots altogether) did not find any such trend in q as was seen in RGO data.…”

Section: Penumbra To Umbra Area Ratiomentioning

confidence: 75%

Extending the sunspot area series from Kodaikanal Solar Observatory

Jha

Hegde

Priyadarshi

et al. 2022

Front. Astron. Space Sci.

View full text Add to dashboard Cite

Kodaikanal Solar Observatory (KoSO) possesses one of world’s longest and homogeneous records of sunspot observations that span more than a century (1904–2017). Interestingly, these observations (originally recorded in photographic plates/films) were taken with the same setup over this entire time period which makes this data unique and best suitable for long-term solar variability studies. A large part of this data, between 1921–2011, were digitized earlier and a catalog containing the detected sunspot parameters (e.g., area and location) was published in Mandal et al. (2017). In this article, we extend the earlier catalog by including new sets of data between 1904–1921 and 2011–2017. To this end, we digitize and calibrate these new datasets which include resolving the issue of random image orientation. We fix this by comparing the KoSO images with co-temporal data from Royal Greenwich Observatory. Following that, a semi-automated sunspot detection and automated umbra detection algorithm are implemented onto these calibrated images to detect sunspots and umbra. Additionally, during this catalog updation, we also filled data gaps in the existing KoSO sunspot catalog (1921–2011) by virtue of re-calibrating the “rouge” plates. This updated sunspot area series covering nearly 115 years (1904–2017) are being made available to the community and will be a unique source to study the long term variability of the Sun.

show abstract

Section: Penumbra To Umbra Area Ratiomentioning

confidence: 75%

Extending the sunspot area series from Kodaikanal Solar Observatory

Jha

Hegde

Priyadarshi

et al. 2022

Front. Astron. Space Sci.

View full text Add to dashboard Cite

show abstract

“…On the other hand, Takalo (2023) investigated Debrecen sunspot groups and indicated that average (q)-value was ∼5.74. Hou et al (2022) used Yunnan…”

Section: Discussionmentioning

confidence: 99%

“…From the above-mentioned graphs, it is clear that q avg does not exhibit any particular trend in any of the hemispheres as well as the full solar disk and hence we therefore may conclude that this ratio is independent of the latitude distribution of a spot (Antalová, 1971;Hathaway, 2013;Jha, Mandal, and Banerjee, 2019;Hou et al, 2022;Takalo, 2023).…”

Section: Variations Of the Penumbra-umbra Area Ratio With Latitudementioning

confidence: 94%

Temporal and Periodic Analysis of Penumbra-Umbra Ratio for the Last Four Solar Cycles

Chowdhury

Kılçık

Saha

et al. 2023

Preprint

View full text Add to dashboard Cite

We investigate the long-term dynamic behavior of the sunspot penum8bra to umbra area ratio by analyzing the Debrecen Photoheliographic Data9 (DPD) of sunspot groups during the period 1976–2017 (Solar Cycles 21-24). We consider all types of spots and notice that the average penumbra-umbra ratio does not exhibit any significant variation with spot latitudes, solar cycle phases as well as sunspot cycle strengths. However, the behavior of this ratio is different when we consider the latitudinal distribution of the northern and southern hemisphere separately. Our analysis indicates that the average spot ratio varies from 5.5 to 6.5 and for very large sunspots (> 5000 μhem; one μhem is 10-6 the area of millionth of visual solar hemisphere) its value rises to about 8.3. Further, we found that this ratio exhibit some kind of solar cycle trend for both smaller (area <100 μhem) and large (area > 100 μhem) sunspots. Finally, we have studied the periodic and quasi-periodic variations present in this ratio time series by the multitaper method (MTM) and wavelet technique. We found that along with the ∼11-years (solar cycle period), the penumbra to umbra area ratio data also show several mid-term variations, specifically, Rieger type and quasi-biennial periodicities.We also found that the Rieger-type of periods occurs in all cycles, but the temporal evolution and the modulation of these types of periodicities are different in different solar cycles.

show abstract

Temporal and Latitudinal Variation in Penumbra-Umbra Ratios of the Sunspots: Analyses of RGO, Kodaikanal and Debrecen Databases

Takalo

2023

Sol Phys

View full text Add to dashboard Cite

We study the latitudinal distribution and temporal evolution of the sunspot penumbra-umbra ratio ($q$ q ) for the even and odd Solar Cycles 12 – 24 of RGO sunspot groups, SC21 – SC24 of Debrecen sunspot groups and Kodaikanal sunspot dataset for SC16 – SC24. We find that RGO even (odd) Cycles have $q$ q -values 5.20 (4.75), Kodaikanal even (odd) cycles have $q$ q -values 5.27 (5.43), and Debrecen cycles have $q$ q -value 5.74 on the average.We also show that $q$ q is at its lowest around the Equator of the Sun and increases towards higher latitudes having maximum values at about 10 – 25 degrees. This is understandable because smaller sunspots and groups locate nearer to the Equator and have smaller $q$ q -values than larger sunspots and groups, which maximize at about 10 – 20 degrees at both hemispheres. The error limits are very wide, and, thus, the confidence in this result is somewhat vague.For the Debrecen dataset, we find a deep valley in the temporal $q$ q -values before the middle of the cycle. We show that this exists simultaneously with the Gnevyshev gap (GG) in the graph of the total and umbral areas of the large sunspot groups. Other databases do not show GG in their $q$ q -graphs, although GG exists in their temporal total area and umbral area.

show abstract

Chinese Sunspot Drawings and Their Digitization—(VII) Sunspot Penumbra to Umbra Area Ratio Using the Hand-Drawing Records from Yunnan Observatories

Cited by 6 publications

References 22 publications

Extending the sunspot area series from Kodaikanal Solar Observatory

Extending the sunspot area series from Kodaikanal Solar Observatory

Temporal and Periodic Analysis of Penumbra-Umbra Ratio for the Last Four Solar Cycles

Temporal and Latitudinal Variation in Penumbra-Umbra Ratios of the Sunspots: Analyses of RGO, Kodaikanal and Debrecen Databases

Contact Info

Product

Resources

About