scholarly journals The presence of large sunspots near the central solar meridian at the times of modern Japanese auroral observations

2006 ◽  
Vol 24 (10) ◽  
pp. 2743-2758 ◽  
Author(s):  
D. M. Willis ◽  
R. Henwood ◽  
F. R. Stephenson
Keyword(s):  
Success Rate ◽  
Geomagnetic Storms ◽  
East Asian ◽  
Solar Observatory ◽  
The Sun ◽  
Royal Greenwich Observatory ◽  
Heliospheric Observatory ◽  
The Past ◽  
Experienced Observer ◽  
The Times

Abstract. The validity of a technique developed by the authors to identify historical occurrences of intense geomagnetic storms, which is based on finding approximately coincident observations of sunspots and aurorae recorded in East Asian histories, is corroborated using more modern sunspot and auroral observations. Scientific observations of aurorae in Japan during the interval 1957–2004 are used to identify geomagnetic storms that are sufficiently intense to produce auroral displays at low geomagnetic latitudes. By examining white-light images of the Sun obtained by the Royal Greenwich Observatory, the Big Bear Solar Observatory, the Debrecen Heliophysical Observatory and the Solar and Heliospheric Observatory spacecraft, it is found that a sunspot large enough to be seen with the unaided eye by an "experienced" observer was located reasonably close to the central solar meridian immediately before all but one of the 30 distinct Japanese auroral events, which represents a 97% success rate. Even an "average" observer would probably have been able to see a sunspot with the unaided eye before 24 of these 30 events, which represents an 80% success rate. This corroboration of the validity of the technique used to identify historical occurences of intense geomagnetic storms is important because early unaided-eye observations of sunspots and aurorae provide the only possible means of identifying individual historical geomagnetic storms during the greater part of the past two millennia.

scholarly journals The presence of large sunspots near the central solar meridian at the times of major geomagnetic storms

2009 ◽  
Vol 27 (1) ◽  
pp. 185-197 ◽  
Author(s):  
D. M. Willis ◽  
R. Henwood ◽  
F. R. Stephenson
Keyword(s):  
Success Rate ◽  
Geomagnetic Storms ◽  
Solar Observatory ◽  
Royal Greenwich Observatory ◽  
Heliospheric Observatory ◽  
Original Technique ◽  
The Past ◽  
Experienced Observer ◽  
The Times ◽  
Magnetic Index

Abstract. A further study is made of the validity of a technique developed by the authors to identify historical occurrences of intense geomagnetic storms, which is based on finding approximately coincident observations of sunspots and aurorae recorded in East Asian histories. Previously, the validity of this technique was corroborated using scientific observations of aurorae in Japan during the interval 1957–2004 and contemporaneous white-light images of the Sun obtained by the Royal Greenwich Observatory, the Big Bear Solar Observatory, the Debrecen Heliophysical Observatory, and the Solar and Heliospheric Observatory spacecraft. The present investigation utilises a list of major geomagnetic storms in the interval 1868–2008, which is based on the magnitude of the AA* magnetic index, and reconstructed solar images based on the sunspot observations acquired by the Royal Greenwich Observatory during the shorter interval 1874–1976. It is found that a sunspot large enough to be seen with the unaided eye by an "experienced" observer was located reasonably close to the central solar meridian for almost 90% of these major geomagnetic storms. Even an "average" observer would easily achieve a corresponding success rate of 70% and this success rate increases to about 80% if a minority of ambiguous situations are interpreted favourably. The use of information on major geomagnetic storms, rather than modern auroral observations from Japan, provides a less direct corroboration of the technique for identifying historical occurrences of intense geomagnetic storms, if only because major geomagnetic storms do not necessarily produce auroral displays over East Asia. Nevertheless, the present study provides further corroboration of the validity of the original technique for identifying intense geomagnetic storms. This additional corroboration of the original technique is important because early unaided-eye observations of sunspots and aurorae provide the only possible means of identifying individual geomagnetic storms during the greater part of the past two millennia.

scholarly journals Sporadic aurorae observed in East Asia

2007 ◽  
Vol 25 (2) ◽  
pp. 417-436 ◽  
Author(s):  
D. M. Willis ◽  
F. R. Stephenson ◽  
Keyword(s):  
United States ◽  
East Asia ◽  
Geomagnetic Storms ◽  
East Asian ◽  
Scientific Information ◽  
The United States ◽  
Royal Greenwich Observatory ◽  
Historical Sources ◽  
Approximate Location ◽  
Auroral Luminosity

Abstract. All the accessible auroral observations recorded in Chinese and Japanese histories during the interval AD 1840–1911 are investigated in detail. Most of these auroral records have never been translated into a Western language before. The East Asian auroral reports provide information on the date and approximate location of each auroral observation, together with limited scientific information on the characteristics of the auroral luminosity such as colour, duration, extent, position in the sky and approximate time of occurrence. The full translations of the original Chinese and Japanese auroral records are presented in an appendix, which contains bibliographic details of the various historical sources. (There are no known reliable Korean observations during this interval.) A second appendix discusses a few implausible "auroral" records, which have been rejected. The salient scientific properties of all exactly dated and reliable East Asian auroral observations in the interval AD 1840–1911 are summarised succinctly. By comparing the relevant scientific information on exactly dated auroral observations with the lists of great geomagnetic storms compiled by the Royal Greenwich Observatory, and also the tabulated values of the Ak (Helsinki) and aa (Greenwich and Melbourne) magnetic indices, it is found that 5 of the great geomagnetic storms (aa>150 or Ak>50) during either the second half of the nineteenth century or the first decade of the twentieth century are clearly identified by extensive auroral displays observed in China or Japan. Indeed, two of these great storms produced auroral displays observed in both countries on the same night. Conversely, at least 29 (69%) of the 42 Chinese and Japanese auroral observations occurred at times of weak-to-moderate geomagnetic activity (aa or Ak≤50). It is shown that these latter auroral displays are very similar to the more numerous (about 50) examples of sporadic aurorae observed in the United States during the interval AD 1880–1940. The localised nature and spatial structure of some sporadic aurorae observed in East Asia is indicated by the use of descriptive terms such as "lightning", "rainbow", "streak" and "grid".

scholarly journals Using CME Progenitors to Assess CME Geoeffectiveness

2021 ◽  
Vol 257 (2) ◽  
pp. 33
Author(s):  
Kashvi Mundra ◽  
V. Aparna ◽  
Petrus Martens
Keyword(s):  
Magnetic Field ◽  
Extreme Ultraviolet ◽  
Geomagnetic Storms ◽  
Solar Surface ◽  
Axial Direction ◽  
Solar Observatory ◽  
Field Orientation ◽  
Heliospheric Observatory ◽  
Doppler Imager ◽  
Time Period

Abstract There have been a few previous studies claiming that the effects of geomagnetic storms strongly depend on the orientation of the magnetic cloud portion of coronal mass ejections (CMEs). Aparna & Martens, using halo-CME data from 2007 to 2017, showed that the magnetic field orientation of filaments at the location where CMEs originate on the Sun can be used to credibly predict the geoeffectiveness of the CMEs being studied. The purpose of this study is to extend their survey by analyzing the halo-CME data for 1996–2006. The correlation of filament axial direction on the solar surface and the corresponding Bz signatures at L1 are used to form a more extensive analysis for the results previously presented by Aparna & Martens. This study utilizes Solar and Heliospheric Observatory Extreme-ultraviolet Imaging Telescope 195 Å, Michelson Doppler Imager magnetogram images, and Kanzelhöhe Solar Observatory and Big Bear Solar Observatory Hα images for each particular time period, along with ACE data for interplanetary magnetic field signatures. Utilizing all these, we have found that the trend in Aparna & Martens’ study of a high likelihood of correlation between the axial field direction on the solar surface and Bz orientation persists for the data between 1996 and 2006, for which we find a match percentage of 65%.

A Deep Pocket for the Truth of the Times

2017 ◽  
Author(s):  
Michael Germana
Keyword(s):  
Music Criticism ◽  
Invisible Man ◽  
The Past ◽  
Historical View ◽  
Sense Of Time ◽  
Cultural Forms ◽  
The Times ◽  
Musical Forms

Chapter 5 treats Ellison’s music criticism as an expression of his commitment to durational time and a critique of cultural forms like bebop that, in Ellison’s estimation, lend form to a discontinuous present. Rather than suggest, as many critics have, that Ellison was simply nostalgic for danceable swing music or hostile toward emerging musical forms, this chapter shows that Ellison’s primary criticism of bebop is that it formalizes a discontinuous sense of time and thereby affirms an historical view of the past structured by an analogous, sequentially static sense of time. Ellison’s problem with bebop, in other words, is neither musicological nor sociological, but temporal. Folk jazz and the blues, by contrast, affirm a durational view of time in the form of a “pocket” or groove entirely unlike the spatialized groove of history described in Invisible Man. In short, Ellison finds in musical grooves antidotes to the groove of history.

Vietnamese Historical Writing

2018 ◽  
Author(s):  
Patricia Pelley
Keyword(s):  
Cold War ◽  
East Asian ◽  
History Writing ◽  
Southern State ◽  
The Past ◽  
South Vietnam ◽  
Political Function ◽  
Different Types ◽  
The Cold War ◽  
North Vietnam

This chapter demonstrates how the process of decolonization and the ensuing separation of Vietnam into a northern and southern state as part of the Cold War in Asia led to different types of history-writing. In both Vietnamese regimes, the writing of history had to serve the state, and in both countries historians emphasized its political function. Whereas North Vietnam located itself in an East Asian and Marxist context, historians of South Vietnam positioned it within a Southeast Asian setting and took a determinedly anti-communist position. After 1986—over a decade after reunification—with past tensions now relaxed, the past could be revaluated more openly under a reformist Vietnamese government that now also permitted much greater interaction with foreign historians.

scholarly journals The Solar and Heliospheric Observatory

1984 ◽  
Vol 86 ◽  
pp. 155-158 ◽  
Author(s):  
Giancarlo Noci
Keyword(s):  
Solar Physics ◽  
Grazing Incidence ◽  
Spectral Irradiance ◽  
The Sun ◽  
Solar Dynamics Observatory ◽  
Solar Constant ◽  
Heliospheric Observatory ◽  
Explorer Mission ◽  
Solar Dynamics ◽  
Euv Spectrum

In the past years several space missions have been proposed for the study of the Sun and of the Heliosphere. These missions were intended to clarify various different aspects of solar physics. For example, the GRIST (Grazing Incidence Solar Telescope) mission was intended as a means to improve our knowledge of the upper transition region and low corona through the detection of the solar EUV spectrum with a spatial resolution larger than in previous missions; the DISCO (Dual Spectral Irradiance and Solar Constant Orbiter) and SDO (Solar Dynamics Observatory) missions were proposed to gat observational data about the solar oscillations better than those obtained from ground based instruments; the SOHO (Solar and Heliospheric Observatory) mission was initially proposed to combine the properties of GRIST with the study of the extended corona (up to several radii of heliocentric distance) by observing the scattered Ly-alpha and OVI radiation, which was also the basis of the SCE (Solar Corona Explorer) mission proposal; the development of the interest about the variability of the Sun, both in itself and for its consequences in the history of the Earth, led to propose observations of the solar constant (included in DISCO).

East Asian winter monsoon variation during the last 3000 years as recorded in a subtropical mountain lake, northeastern Taiwan

The Holocene ◽  
2021 ◽  
pp. 095968362110190
Author(s):  
Tsai-Wen Lin ◽  
Stefanie Kaboth-Bahr ◽  
Kweku Afrifa Yamoah ◽  
André Bahr ◽  
George Burr ◽  
...  
Keyword(s):  
Grain Size ◽  
East Asian Winter Monsoon ◽  
East Asian ◽  
Winter Monsoon ◽  
Mountain Lake ◽  
Sediment Grain Size ◽  
Global Monsoon ◽  
Asian Winter Monsoon ◽  
The Past ◽  
Monsoon System

The East Asian Winter Monsoon (EAWM) is a fundamental part of the global monsoon system that affects nearly one-quarter of the world’s population. Robust paleoclimate reconstructions in East Asia are complicated by multiple sources of precipitation. These sources, such as the EAWM and typhoons, need to be disentangled in order to understand the dominant source of precipitation influencing the past and current climate. Taiwan, situated within the subtropical East Asian monsoon system, provides a unique opportunity to study monsoon and typhoon variability through time. Here we combine sediment trap data with down-core records from Cueifong Lake in northeastern Taiwan to reconstruct monsoonal rainfall fluctuations over the past 3000 years. The monthly collected grain-size data indicate that a decrease in sediment grain size reflects the strength of the EAWM. End member modelling analysis (EMMA) on sediment core and trap data reveals two dominant grain-size end-members (EMs), with the coarse EM 2 representing a robust indicator of EAWM strength. The downcore variations of EM 2 show a gradual decrease over the past 3000 years indicating a gradual strengthening of the EAWM, in agreement with other published EAWM records. This enhanced late-Holocene EAWM can be linked to the expansion of sea-ice cover in the western Arctic Ocean caused by decreased summer insolation.

scholarly journals INTRODUCTION: HISTORY FROM BETWEEN AND THE GLOBAL CIRCULATIONS OF THE PAST IN ASIA AND EUROPE, 1600–1950

2020 ◽  
pp. 1-16
Author(s):  
LEIGH K. JENCO ◽  
JONATHAN CHAPPELL
Keyword(s):  
East Asia ◽  
Intellectual History ◽  
East Asian ◽  
Historical Narratives ◽  
Subjective Feeling ◽  
Historical Knowledge ◽  
Introduction History ◽  
The Past ◽  
Local Contexts ◽  
Forms Of Knowledge

Abstract This article argues for a ‘history from between’ as the best lens through which to understand the construction of historical knowledge between East Asia and Europe. ‘Between’ refers to the space framed by East Asia and Europe, but also to the global circulations of ideas in that space, and to the subjective feeling of embeddedness in larger-than-local contexts that being in such a space makes possible. Our contention is that the outcomes of such entanglements are not merely reactive forms of knowledge, of the kind implied by older studies of translation and reception in global intellectual history. Instead they are themselves ‘co-productions’: they are the shared and mutually interactive inputs to enduring modes of uses of the past, across both East Asian and European traditions. Taking seriously the possibility that interpretations of the past were not transferred, but rather were co-produced between East Asia and Europe, we reconstruct the braided histories of historical narratives that continue to shape constructions of identity throughout Eurasia.

scholarly journals Theoretical Review of Secular Instabilities in the Sun

1980 ◽  
Vol 5 ◽  
pp. 441-444
Author(s):  
M. Gabriel
Keyword(s):  
Inner Core ◽  
Neutrino Flux ◽  
Radial Oscillation ◽  
Solar Model ◽  
The Sun ◽  
Standard Solar Model ◽  
The Past ◽  
Low Order

In this review we discuss the problems raised by the discovery that the sun was, in the past, unstable towards non-radial oscillations.In 1972, Fowler (1972), in an attempt to explain the low-neutrino flux measured in Davis’ experiment (now 1.6 snu, while the standard solar model predicts 4.4 snu) suggested that the sun could have undergone, some 10 years ago, a change in structure because of sudden mixing of the inner core. During the same year Dilke and Gough (1972) suggested the sun is unstable to low-order gravity modes (g+ modes) of non-radial oscillation and that the mixing is triggered when the amplitude of the oscillation becomes large enough.

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