scholarly journals Solar activity reconstructed over the last 7000 years: The influence of geomagnetic field changes

2006 ◽  
Vol 33 (8) ◽  
Author(s):  
I. G. Usoskin ◽  
S. K. Solanki ◽  
M. Korte
Keyword(s):  
Solar Activity ◽  
Geomagnetic Field

scholarly journals Topside equatorial zonal ion velocities measured by C/NOFS during rising solar activity

2014 ◽  
Vol 32 (2) ◽  
pp. 69-75 ◽  
Author(s):  
W. R. Coley ◽  
R. A. Stoneback ◽  
R. A. Heelis ◽  
M. R. Hairston
Keyword(s):  
Solar Activity ◽  
Local Time ◽  
Geomagnetic Field ◽  
General Pattern ◽  
Magnetic Latitude ◽  
Ion Drifts ◽  
F Region ◽  
Westerly Flow ◽  
Solar Local Time ◽  
Ion Velocity

Abstract. The Ion Velocity Meter (IVM), a part of the Coupled Ion Neutral Dynamic Investigation (CINDI) instrument package on the Communication/Navigation Outage Forecast System (C/NOFS) spacecraft, has made over 5 yr of in situ measurements of plasma temperatures, composition, densities, and velocities in the 400–850 km altitude range of the equatorial ionosphere. These measured ion velocities are then transformed into a coordinate system with components parallel and perpendicular to the geomagnetic field allowing us to examine the zonal (horizontal and perpendicular to the geomagnetic field) component of plasma motion over the 2009–2012 interval. The general pattern of local time variation of the equatorial zonal ion velocity is well established as westward during the day and eastward during the night, with the larger nighttime velocities leading to a net ionospheric superrotation. Since the C/NOFS launch in April 2008, F10.7 cm radio fluxes have gradually increased from around 70 sfu to levels in the 130–150 sfu range. The comprehensive coverage of C/NOFS over the low-latitude ionosphere allows us to examine variations of the topside zonal ion velocity over a wide level of solar activity as well as the dependence of the zonal velocity on apex altitude (magnetic latitude), longitude, and solar local time. It was found that the zonal ion drifts show longitude dependence with the largest net eastward values in the American sector. The pre-midnight zonal drifts show definite solar activity (F10.7) dependence. The daytime drifts have a lower dependence on F10.7. The apex altitude (magnetic latitude) variations indicate a more westerly flow at higher altitudes. There is often a net topside subrotation at low F10.7 levels, perhaps indicative of a suppressed F region dynamo due to low field line-integrated conductivity and a low F region altitude at solar minimum.

scholarly journals An early mid-latitude aurora observed by Rozier (Béziers, 1780)

2020 ◽  
Vol 38 (6) ◽  
pp. 1139-1147
Author(s):  
Chiara Bertolin ◽  
Fernando Domínguez-Castro ◽  
Lavinia de Ferri
Keyword(s):  
Solar Activity ◽  
Geomagnetic Field ◽  
18Th Century ◽  
Geomagnetic Latitude ◽  
Careful Analysis ◽  
Universal Time ◽  
Low Latitudes ◽  
Solar Storms ◽  
Mass Ejection ◽  
Atmospheric Phenomena

Abstract. Aurora observations are an uncommon phenomenon at low and mid latitudes that, at the end of the 18th century, were not well known and understood. Low and mid geomagnetic latitude aurora observations provide information about episodes of intense solar storms associated with flares and outstanding coronal mass ejection (CME) and about the variation of the geomagnetic field. However, for many observers at mid and low latitudes, the features of a northern light were unknown, so they could easily report it as a phenomenon without explanation. In this work, we found that an earlier mid geomagnetic latitude aurora was observed in Beauséjour, close to Béziers (43∘19′ N, 3∘13′ E), France, by the abbot François Rozier. He was a meticulous botanist, doctor and agronomist with a special interest in atmospheric phenomena. On 15 August 1780, from 19:55 to 20:07 (Universal Time), François Rozier observed a “phosphoric cloud”. A careful analysis of the report indicates that he was reporting an auroral event. The recovery of auroral events at low and mid latitude during the 1780s is very useful for shedding light on solar activity during this period because there are few records of sunspot observations.

Possible Influence of the Solar Eclipse on the Global Geomagnetic Field

2017 ◽  
Vol 13 (S335) ◽  
pp. 167-170
Author(s):  
Jung-Hee Kim ◽  
Heon-Young Chang
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Solar Eclipse ◽  
Geomagnetic Field ◽  
Geomagnetic Observatory ◽  
Geomagnetic Disturbances ◽  
Solar Eclipses ◽  
A Site

AbstractWe investigate the geomagnetic field variations recorded by INTERMAGNET geomagnetic observatories. We confirm that the effect of solar eclipse can be seen over an interval of 180 minutes centered at the time of maximum eclipse on a site of a geomagnetic observatory. It is found that the effect of the solar eclipse on the geomagnetic field becomes conspicuous as the magnitude of a solar eclipse becomes larger. The effect of solar eclipses is more evident in the second half of the path of Moon’s shadow. We also find that the effect can be overwhelmed, more sensitively by geomagnetic disturbances than by solar activity of solar cycle.

scholarly journals Statistical issues about solar–climate relations

2010 ◽  
Vol 6 (5) ◽  
pp. 565-573 ◽  
Author(s):  
P. Yiou ◽  
E. Bard ◽  
P. Dandin ◽  
B. Legras ◽  
P. Naveau ◽  
...  
Keyword(s):  
Time Series ◽  
Solar Activity ◽  
Geomagnetic Field ◽  
Degrees Of Freedom ◽  
Statistical Significance ◽  
Data Sets ◽  
Statistical Issues ◽  
The Relationship ◽  
Temperature Time ◽  
Field Variability

Abstract. The relationship between solar activity and temperature variation is a frequently discussed issue in climatology. This relationships is usually hypothesized on the basis of statistical analyses of temperature time series and time series related to solar activity. Recent studies (Le Mouël et al., 2008, 2009; Courtillot et al., 2010) focus on the variabilities of temperature and solar activity records to identify their relationships. We discuss the meaning of such analyses and propose a general framework to test the statistical significance for these variability-based analyses. This approach is illustrated using European temperature data sets and geomagnetic field variations. We show that tests for significant correlation between observed temperature variability and geomagnetic field variability is hindered by a low number of degrees of freedom introduced by excessively smoothing the variability-based statistics.

scholarly journals MODEL EMPIRIS HARI TENANG VARIASI MEDAN GEOMAGNET DI STASIUN GEOMAGNET TONDANO MANADO

2016 ◽  
Vol 12 (2) ◽  
pp. 115
Author(s):  
Lukman Arifin ◽  
John Maspupu
Keyword(s):  
Solar Activity ◽  
Local Time ◽  
Empirical Model ◽  
Geomagnetic Field ◽  
Daily Variation ◽  
Geomagnetic Disturbance ◽  
Time Interval ◽  
Field Variation ◽  
Geomagnetic Field Variation ◽  
Expression Form

Penentuan model empiris hari tenang variasi medan geomagnet dikonstruksi berdasarkan data geomagnet dari stasiun geomagnet (SG) Badan Meteorologi Klimatologi dan Geofisika (BMKG) Tondano, Manado. Hari tenang variasi medan geomagnet dinyatakan sebagai fungsi dari keempat komponen atau variabel yang mempengaruhinya yaitu: aktivitas matahari SA (solar activity), hari dalam setahun DOY (date of year), usia bulan LA (lunar age) dan waktu lokal LT (local time). Dalam bentuk matematis ditulis sebagai, EMQD ( SA, DOY, LA, LT ) = f(SA). g(DOY). h(LA). m(LT). Model empiris yang didasarkan pada fungsi kecocokan ini terdiri dari 270 bentuk ekspresi matematik. Sedangkan bentuk-bentuk ekspresi matematik ini juga mencakup proses-proses non-linier yang tak dapat diabaikan dalam model empiris hari tenang variasi medan geomagnet tersebut. Model empiris ini dapat ditiru atau dikonstruksi kembali pada suatu selang waktu yang relatif panjang (misalnya satu siklus matahari), asalkan kondisi geomagnet selalu berada dalam keadaan tenang. Kontribusi dari model empiris hari tenang ini akan memberikan informasi tentang gangguan geomagnet yang ada di stasiun geomagnet Tondano (Nilai Gangguan geomagnet = Nilai variasi medan geomagnet yang terukur – Nilai model empiris hari tenang). Dengan demikian model ini akan memberikan informasi gangguan geomagnet untuk operasi survey geomagnet disekitar stasiun geomagnet Tondano, Manado. Kata kunci : Model empiris, Hari tenang, Variasi medan geomagnet. The determination an empirical model of the quiet daily geomagnetic field variation that is constructed based on geomagnetic data from Tondano, Manado station geomagnetic This quiet daily of geomagnetic field variation was described as a function of four variables that its influence, these are solar activity (SA), day of year (DOY), lunar age (LA) and local time (LT). In the mathematically writes: EMQD ( SA, DOY, LA, LT ) = f(SA). g(DOY). h(LA). m(LT). The empirical model based on this fitting function consist of 270 coefficients which included in expression form of mathematic. While, expression form of this mathematic also comprise nonlinear processes which can not minimized in the empirical model of the quiet daily geomagnetic field variation. This empirical model can be reconstructed on the time interval that is long relative (for example one solar cycle). Provided that, under geomagnetic quiet conditions. Contribution of this empirical model of the quiet daily variation is can give information about the existence of geomagnetic disturbance at Tondano (value of geomagnetic disturbance equal value of measurable geomagnetic field variation minus value of empirical model of the quiet daily variation). Thus, information about the existence of this geomagnetic disturbance very useful for necessity geomagnetic survey at Tondano, Manado geomagnetic station. Keywords: Empirical model, the quiet daily variation, geomagnetic field variation.

scholarly journals Solar activity and geomagnetic field secular variations

2010 ◽  
Vol 16 (2) ◽  
pp. 5-11
Author(s):  
P.V. Sumaruk ◽  
◽  
T.P. Sumaruk ◽  
Keyword(s):  
Solar Activity ◽  
Geomagnetic Field ◽  
Secular Variations

scholarly journals Historical Aurora Borealis Observations in Anatolia during medieval period: Implications for the past solar activity

2019 ◽  
Author(s):  
Nafiz Maden
Keyword(s):  
Solar Activity ◽  
Middle East ◽  
Climatic Change ◽  
Geomagnetic Field ◽  
Physical Mechanism ◽  
Climatic Changes ◽  
Medieval Period ◽  
Historical Texts ◽  
Aurora Borealis ◽  
The Past

Abstract. In this paper, it is reviewed the relationships between the aurora observations, past solar activity and climatic change in Anatolia during medieval period. For this purpose, it is presented two historical aurora catalogs for Anatolia and Middle East regions at various dates in order to understand the past solar activity and possible physical mechanism using historical texts, chronicles and other auroral records. The available catalogs in literature are covered records observed in the Europe, Japan, China, Russia and Middle East. There is no study dealing only with the historical aurora observations recorded in Anatolia. The data of the catalog strongly support that there is a considerable relationship between the aurora activity and past strong solar activity. An unusually high auroral activity during the years around 1100 in Anatolia and Middle East is quite consistent with the past solar variability, geomagnetic field intensity and planetary climatic changes drastically impacting on the economy and human events.

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