scholarly journals Relation of zonal plasma drift and wind in the equatorial F region as derived from CHAMP observations

2013 ◽  
Vol 31 (6) ◽  
pp. 1035-1044 ◽  
Author(s):  
J. Park ◽  
H. Lühr
Keyword(s):  
Magnetic Field ◽  
Ionospheric Plasma ◽  
Wind Effect ◽  
Field Observations ◽  
Republic Of China ◽  
Ion Drift ◽  
Plasma Drift ◽  
F Region ◽  
The Republic ◽  
Westward Drift

Abstract. In this paper we estimate zonal plasma drift in the equatorial ionospheric F region without counting on ion drift meters. From June 2001 to June 2004 zonal plasma drift velocity is estimated from electron, neutral, and magnetic field observations of Challenging Mini-satellite Payload (CHAMP) in the 09:00–20:00 LT sector. The estimated velocities are validated against ion drift measurements by the Republic of China Satellite-1/Ionospheric Plasma and Electrodynamics Instrument (ROCSAT-1/IPEI) during the same period. The correlation between the CHAMP (altitude ~ 400 km) estimates and ROCSAT-1 (altitude ~ 600 km) observations is reasonably high (R ≈ 0.8). The slope of the linear regression is close to unity. However, the maximum westward drift and the westward-to-eastward reversal occur earlier for CHAMP estimates than for ROCSAT-1 measurements. In the equatorial F region both zonal wind and plasma drift have the same direction. Both generate vertical currents but with opposite signs. The wind effect (F region wind dynamo) is generally larger in magnitude than the plasma drift effect (Pedersen current generated by vertical E field), thus determining the direction of the F region vertical current.

scholarly journals On developing a new ionospheric plasma index for Brazilian equatorial F region irregularities

2019 ◽  
Vol 37 (5) ◽  
pp. 807-818 ◽  
Author(s):  
Laysa Cristina Araujo Resende ◽  
Clezio Marcos Denardini ◽  
Giorgio Arlan Silva Picanço ◽  
Juliano Moro ◽  
Diego Barros ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Space Weather ◽  
Ionospheric Plasma ◽  
Monitoring Program ◽  
Plasma Irregularities ◽  
Plasma Drift ◽  
F Region ◽  
Maximum Value ◽  
Spread F

Abstract. F region vertical drifts (Vz) are the result of the interaction between ionospheric plasma with the zonal electric field and the Earth's magnetic field. Abrupt variations in Vz are strongly associated with the occurrence of plasma irregularities (spread F) during the nighttime periods. These irregularities are manifestations of space weather in the ionosphere's environment without necessarily requiring a solar burst. In this context, the Brazilian Space Weather Study and Monitoring Program (Embrace) of the National Institute for Space Research (INPE) has been developing different indexes to analyze these ionospheric irregularities in the Brazilian sector. Therefore, the main purpose of this work is to produce a new ionospheric scale based on the analysis of the ionospheric plasma drift velocity, named AV. It is based on the maximum value of Vz (Vzp), which in turn is calculated through its relationship with the virtual height parameter, h′F, measured by the Digisonde Portable Sounder (DPS-4D) installed in São Luís (2∘ S, 44∘ W; dip: −2.3∘). This index quantifies the time relationship between the Vz peak and the irregularity observed in the ionograms. Thus, in this study, we analyzed 7 years of data, between 2009 and 2015, divided by season in order to construct a standardized scale. The results show there is a delay of at least 15 min between the Vzp observation and the irregularity occurrence. Finally, we believe that this proposed index allows for evaluating the impacts of ionospheric phenomena in the space weather environment.

scholarly journals On developing a new ionospheric plasma index for the Brazilian equatorial F region irregularities

2019 ◽  
Author(s):  
Laysa Cristina Araujo Resende ◽  
Clezio Marcos Denardini ◽  
Giorgio Arlan Silva Picanço ◽  
Juliano Moro ◽  
Diego Barros ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Space Weather ◽  
Ionospheric Plasma ◽  
Monitoring Program ◽  
Plasma Irregularities ◽  
Plasma Drift ◽  
F Region ◽  
Maximum Value ◽  
Spread F ◽  
Time Relation

Abstract. F region vertical drifts (Vz) are the result of the interaction between the ionospheric plasma with the zonal electric field and the Earth's magnetic field. Abrupt variations in Vz are strongly associated with the occurrence of plasma irregularities (spread-F) during the nighttime periods. These irregularities are manifestations of the space weather in the ionosphere environment without necessarily require a solar burst. In this context, the Brazilian Space Weather Study and Monitoring Program (Embrace) of the National Institute for Space Research (INPE) has been developing different indexes to analyze these ionospheric irregularities in the Brazilian sector. Therefore, the main purpose of this work was to produce a new ionospheric scale based on the analysis of the ionospheric plasma drift velocity, named AV. It is based in the maximum value of Vz (Vzp), which in turn is calculated through its relationship with the virtual height parameter, h’F, measured by the Digisonde Portable Sounder (DPS-4D) installed in São Luís (2° S, 44° O, dip: −2,3°). This index quantifies the time relation between the Vz peak and the irregularity observed in the ionogramas. Thus, in this study, we analyzed 8 years of data, between 2009 and 2015, divided by season in order to construct a standardized scale. The results show there is a delay of at least 15 minutes between Vzp observation and the irregularity occurrence. Finally, we believe that this proposed index allow evaluating the impacts of ionospheric phenomena in the Space Weather environment recently.

scholarly journals Numerical Simulation of the Time Evolution of Small-Scale Irregularities in the F-Layer Ionospheric Plasma

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
O. V. Mingalev ◽  
G. I. Mingaleva ◽  
M. N. Melnik ◽  
V. S. Mingalev
Keyword(s):  
Magnetic Field ◽  
Time Evolution ◽  
Ionospheric Plasma ◽  
Debye Length ◽  
Small Scale ◽  
System Of Equations ◽  
Applied Model ◽  
Positive Ions ◽  
F Region ◽  
Small Scale Irregularity

Dynamics of magnetic field-aligned small-scale irregularities in the electron concentration, existing in the F-layer ionospheric plasma, is investigated with the help of a mathematical model. The plasma is assumed to be a rarefied compound consisting of electrons and positive ions and being in a strong, external magnetic field. In the applied model, kinetic processes in the plasma are simulated by using the Vlasov-Poisson system of equations. The system of equations is numerically solved applying a macroparticle method. The time evolution of a plasma irregularity, having initial cross-section dimension commensurable with a Debye length, is simulated during the period sufficient for the irregularity to decay completely. The results of simulation indicate that the small-scale irregularity, created initially in the F-region ionosphere, decays accomplishing periodic damped vibrations, with the process being collisionless.

scholarly journals Disturbed vertical E×B plasma drifts in the equatorial F2 region at solar minimum deduced from observed NmF2 and hmF2 variations

1996 ◽  
Vol 14 (7) ◽  
pp. 733-743 ◽  
Author(s):  
A. V. Mikhailov ◽  
M. Förster ◽  
T. Y. Leschinskaya
Keyword(s):  
Magnetic Field ◽  
Theoretical Model ◽  
Electric Field ◽  
Solar Minimum ◽  
Strong Dependence ◽  
Field Observations ◽  
Model Calculations ◽  
Equatorial Station ◽  
Plasma Drift ◽  
Model Predictions

Abstract. Ground-based ionosonde and magnetic-field observations on the equatorial station Huancayo, ESRO4 neutral-composition measurements, and theoretical model calculations were used to analyze disturbed E×B vertical plasma drift during the phase of solar minimum in 1973. Vertical drifts calculated for disturbed days do not show the systematic decrease often mentioned in publications, and demonstrate strong dependence on IMF-Bz changes. It is confirmed with the help of our drift calculations that Bz turnings to a northward direction result in a decrease (up to reversal) of normal Sq (eastward during daytime and westward at nighttime) in the zonal component of electric field. Southward Bz excursions enhance normal Ey both in daytime and nighttime hours. Model predictions of Ey\\'s reaction to IMF-Bz changes are discussed.

scholarly journals Duskside F-region dynamo currents: its relationship with prereversal enhancement of vertical plasma drift

2010 ◽  
Vol 28 (11) ◽  
pp. 2097-2101 ◽  
Author(s):  
J. Park ◽  
H. Lühr ◽  
B. G. Fejer ◽  
K. W. Min
Keyword(s):  
Current Density ◽  
Solar Maximum ◽  
Field Observations ◽  
Longitudinal Variation ◽  
Plasma Drift ◽  
F Region ◽  
Close Relationship ◽  
E Region ◽  
Current Densities ◽  
First Time

Abstract. From magnetic field observations by CHAMP we estimate F-region dynamo current densities near the sunset terminator during solar maximum years from 2001 to 2002. The dynamo currents are compared with the pre-reversal enhancement (PRE) of vertical plasma drift as observed by ROCSAT-1. The seasonal-longitudinal variation of PRE can be largely related to the F-region dynamo current density, with the correlation coefficient reaching 0.74. The correlation can be further improved if we consider a zonal gradient of the E-region Pedersen conductivity, which also depends on season and longitude. It is widely accepted that the F-region dynamo drives PRE near sunset. For the first time, our observations provide confirmation for the close relationship between the F-region dynamo current density and PRE.

scholarly journals Application of Artificial Intelligence in COVID-19 Pandemic: Bibliometric Analysis

Healthcare ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 441
Author(s):  
Md. Mohaimenul Islam ◽  
Tahmina Nasrin Poly ◽  
Belal Alsinglawi ◽  
Li-Fong Lin ◽  
Shuo-Chen Chien ◽  
...  
Keyword(s):  
Artificial Intelligence ◽  
Bibliometric Analysis ◽  
English Language ◽  
R Package ◽  
Research Area ◽  
Republic Of China ◽  
Comprehensive Picture ◽  
The Usa ◽  
The Republic ◽  
Academy Of Sciences

The application of artificial intelligence (AI) to health has increased, including to COVID-19. This study aimed to provide a clear overview of COVID-19-related AI publication trends using longitudinal bibliometric analysis. A systematic literature search was conducted on the Web of Science for English language peer-reviewed articles related to AI application to COVID-19. A search strategy was developed to collect relevant articles and extracted bibliographic information (e.g., country, research area, sources, and author). VOSviewer (Leiden University) and Bibliometrix (R package) were used to visualize the co-occurrence networks of authors, sources, countries, institutions, global collaborations, citations, co-citations, and keywords. We included 729 research articles on the application of AI to COVID-19 published between 2020 and 2021. PLOS One (33/729, 4.52%), Chaos Solution Fractals (29/729, 3.97%), and Journal of Medical Internet Research (29/729, 3.97%) were the most common journals publishing these articles. The Republic of China (190/729, 26.06%), the USA (173/729, 23.73%), and India (92/729, 12.62%) were the most prolific countries of origin. The Huazhong University of Science and Technology, Wuhan University, and the Chinese Academy of Sciences were the most productive institutions. This is the first study to show a comprehensive picture of the global efforts to address COVID-19 using AI. The findings of this study also provide insights and research directions for academic researchers, policymakers, and healthcare practitioners who wish to collaborate in these domains in the future.

The Normalization of Sino-French Diplomatic Relations in 1964 and the Formation of the “One-China” Principle: Negotiations over Breaking French Diplomatic Relations with the Republic of China Government and the Recognition of the People’s Republic of China as the Sole Legitimate Government

2012 ◽  
Vol 8 (1) ◽  
pp. 252-271
Author(s):  
Madoka Fukuda
Keyword(s):  
The United States ◽  
People’S Republic Of China ◽  
Diplomatic Relations ◽  
People's Republic Of China ◽  
African Countries ◽  
Republic Of China ◽  
The Republic Of China ◽  
The Republic ◽  
The Government ◽  
The One

AbstractThis article examines the substance and modification of the “One-China” principle, which the government of the People’s Republic of China (PRC) pursued in the mid 1960s. Under this principle, a country wishing to establish diplomatic relations with the PRC was required first to break off such relations with the Republic of China (ROC). In 1964 the PRC established diplomatic relations with France. This was its first ambassadorial exchange with a Western government. The PRC, in the negotiations over the establishment of diplomatic relations, attempted to achieve some consensus with France on the matter of “One-China”. The PRC, nevertheless, had to abandon these attempts, even though it demanded fewer conditions of France than of the United States (USA), Japan and other Western countries in the 1970s. The PRC had demanded adherence to the “One-China” principle since 1949. France, however, refused to accept this condition. Nevertheless, the PRC established diplomatic relations with France before the latter broke off relations with the ROC. Subsequently, the PRC abandoned the same condition in negotiations with the African governments of the Republic of Congo, Central Africa, Dahomey and Mauritania. After the negotiations with France, the PRC began to insist that the joint communiqué on the establishment of diplomatic relations should clearly state that “the Government of the People’s Republic of China is the sole legal government of China”. However, France refused to insert these words into the communiqué. Afterwards, the PRC nevertheless insisted on putting such a statement into the joint communiqués or exchanges of notes on the establishment of diplomatic relations with the African countries mentioned above. This was done in order to set precedents for making countries accede to the “One-China” principle. The “One-China” principle was, thus, gradually formed in the process of the negotiation and bargaining between the PRC and other governments.

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