scholarly journals The Dalton Minimum and John Dalton’s Auroral Observations

2020 ◽  
Author(s):  
S. M. Silverman ◽  
Hisashi Hayakawa
Keyword(s):  
Solar Activity ◽  
19Th Century ◽  
Modern Science ◽  
Temporal Variations ◽  
Auroral Zone ◽  
Solar Cycles ◽  
Early 19Th Century ◽  
Observational Site ◽  
Solar Eruptions ◽  
Dalton Minimum

In addition to the regular Schwabe cycles of approximately 11 y, “prolonged solar activity minima” have been identified through the direct observation of sunspots and aurorae, as well as proxy data of cosmogenic isotopes. Some of these minima have been regarded as grand solar minima, which are arguably associated with the special state of the solar dynamo and have attracted significant scientific interest. In this paper, we review how these prolonged solar activity minima have been identified. In particular, we focus on the Dalton Minimum, which is named after John Dalton. We review Dalton’s scientific achievements, particularly in geophysics. Special emphasis is placed on his lifelong observations of auroral displays over approximately five decades in Great Britain. Dalton’s observations for the auroral frequency allowed him to notice the scarcity of auroral displays in the early 19th century. We analyze temporal variations in the annual frequency of such displays from a modern perspective. The contemporary geomagnetic positions of Dalton’s observational site make his dataset extremely valuable because his site is located in the sub-auroral zone and is relatively sensitive to minor enhancements in solar eruptions and solar wind streams. His data indicate clear solar cycles in the early 19th century and their significant depression from 1798 to 1824. Additionally, his data reveal a significant spike in auroral frequency in 1797, which chronologically coincides with the “lost cycle” that is believed to have occurred at the end of Solar Cycle 4. Therefore, John Dalton’s achievements can still benefit modern science and help us improve our understanding of the Dalton Minimum.

scholarly journals Temporal variations of different solar activity indices through the solar cycles 21-23

2017 ◽  
pp. 59-70 ◽  
Author(s):  
Ü.D. Gäoker ◽  
J. Singh ◽  
F. Nutku ◽  
M. Priyal
Keyword(s):  
Solar Activity ◽  
Detailed Comparison ◽  
Temporal Variations ◽  
Total Solar Irradiance ◽  
Magnetic Activity ◽  
Unexpected Finding ◽  
Solar Cycles ◽  
Percentage Decrease ◽  
Solar Activity Indices ◽  
Activity Indices

Here, we compare the sunspot counts and the number of sunspot groups (SGs) with variations of total solar irradiance (TSI), magnetic activity, Ca II K-flux, faculae and plage areas. We applied a time series method for extracting the data over the descending phases of solar activity cycles (SACs) 21, 22 and 23, and the ascending phases 22 and 23. Our results suggest that there is a strong correlation between solar activity indices and the changes in small (A, B, C and H-modified Zurich Classification) and large (D, E and F) SGs. This somewhat unexpected finding suggests that plage regions substantially decreased in spite of the higher number of large SGs in SAC 23 while the Ca II K-flux did not decrease by a large amount nor was it comparable with SAC 22 and relates with C and DEF type SGs. In addition to this, the increase of facular areas which are influenced by large SGs, caused a small percentage decrease in TSI while the decrement of plage areas triggered a higher decrease in the magnetic field flux. Our results thus reveal the potential of such a detailed comparison of the SG analysis with solar activity indices for better understanding and predicting future trends in the SACs.

The Interplay between Volcanic and Solar Cooling in the Early 19th Century

2021 ◽  
Author(s):  
Shih-Wei Fang ◽  
Claudia Timmreck ◽  
Johann Jungclaus ◽  
Hauke Schmidt
Keyword(s):  
19Th Century ◽  
Solar Minimum ◽  
Large Scale ◽  
Climate Model ◽  
Volcanic Eruptions ◽  
Early 19Th Century ◽  
Solar Cooling ◽  
Volcanic Events ◽  
Dalton Minimum ◽  
State Of Art

<p>Volcanic eruptions and reduced solar radiance can individually cool our globe through both direct changes in incoming radiation and indirect influences from dynamical processes. However, whether the cooling from the combination of two forcing can be linearly additive, or if additional cooling exists when reduced solar radiance is imposed during volcanic eruptions remains unclear. In this project, by using the state-of-art climate model (MPI-ESM1-2-LR), we found that the total cooling of the two forcing can be additive, but also have additional cooling during the period when volcanic cooling bouncing back to climatology. Our experiments focus on the early 19th century (1791-1850) since the period existed multiple strong volcanic events (especially the 1809 unidentified eruption and 1815 Tambora eruption), a solar minimum (Dalton minimum from 1790-1830), and limited influence from anthropogenic greenhouse gases. In the presentation, we will discuss how volcanic eruptions and different amplitudes of solar reconstructions can individually and together cool the surface through both direct radiative changes and dynamical influences. Our main focus will be how the atmospheric circulation may influence the polar sea ice and large-scale climate patterns when imposing combinations of solar and volcanic forcing.</p>

Solar oblateness & asphericities temporal variations: Outstanding some unsolved issues

2019 ◽  
Vol 15 (S354) ◽  
pp. 232-237
Author(s):  
Jean P. Rozelot ◽  
Alexander G. Kosovichev ◽  
Ali Kilcik
Keyword(s):  
Solar Activity ◽  
Major Change ◽  
Temporal Variations ◽  
Activity Level ◽  
Problem Analysis ◽  
Solar Cycles ◽  
Solar Oblateness ◽  
Subsurface Layers ◽  
Activity Cycles ◽  
Cycle 24

AbstractSolar oblateness has been the subject of several studies dating back to the nineteenth century. Despite difficulties, both theoretical and observational, tangible results have been achieved. However, variability of the solar oblateness with time is still poorly known. How the solar shape evolves with the solar cycle has been a challenging problem. Analysis of the helioseismic data, which are the most accurate measure of the solar structure up to now, leads to the determination of asphericity coefficients which have been found to change with time. We show here that by inverting even coefficients of f-mode oscillation frequency splitting to obtain the oblateness magnitude and its temporal dependence can be inferred. It is found that the oblateness variations lag the solar activity cycles by about 3 years. A major change occurred between solar cycles 23 and 24 is that the oblateness was greater in cycle 24 despite the lower solar activity level. Such results may help to better understand the near-subsurface layers as they strongly impacts the internal dynamics of the Sun and may induce instabilities driving the transport of angular momentum.

The Kitajskaja grammatika (1835) and Bičurin’s ideas on the “mechanism” of Chinese between European and Chinese grammatical traditions

2019 ◽  
Vol 41 (1) ◽  
pp. 57-77
Author(s):  
Anna Di Toro
Keyword(s):  
19Th Century ◽  
Chinese Language ◽  
Early 19Th Century

The main contribution of Bičurin in the field of Chinese language, the Kitajskaja grammatika (1835), is still quite understudied, even though it represents the first grammar of Chinese written in Russian. Through a rapid overview of some of the early grammars of Chinese written by European authors and the analysis of some sections of the book, in which the Russian sinologist expounds the mechanism of Chinese, the paper dwells on the original ideas on this language developed by the Russian sinologist, inspired both by European and Chinese grammatical traditions. A particular attention is devoted to Bičurin’s concept of “mental modification”, related to the linguistic ideas discussed in Europe in the early 19th century.

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