scholarly journals Characterization of the South Atlantic Anomaly

2019 ◽  
Vol 26 (1) ◽  
pp. 25-35
Author(s):  
Khairul Afifi Nasuddin ◽  
Mardina Abdullah ◽  
Nurul Shazana Abdul Hamid
Keyword(s):  
Magnetic Field ◽  
Geomagnetic Storm ◽  
South Atlantic ◽  
Active Period ◽  
The South ◽  
Earth’S Magnetic Field ◽  
South Atlantic Anomaly ◽  
Normal Period ◽  
Earth's Magnetic Field ◽  
Latitude Region

Abstract. This research intends to characterize the South Atlantic Anomaly (SAA) by applying the power spectrum analysis approach. The motivation to study the SAA region is due to its nature. A comparison was made between the stations in the SAA region and outside the SAA region during the geomagnetic storm occurrence (active period) and the normal period where no geomagnetic storm occurred. The horizontal component of the data of the Earth's magnetic field for the occurrence of the active period was taken on 11 March 2011 while for the normal period it was taken on 3 February 2011. The data sample rate used is 1 min. The outcome of the research revealed that the SAA region had a tendency to be persistent during both periods. It can be said that the region experiences these characteristics because of the Earth's magnetic field strength. Through the research, it is found that as the Earth's magnetic field increases, it is likely to show an antipersistent value. This is found in the high-latitude region. The lower the Earth's magnetic field, the more it shows the persistent value as in the middle latitude region. In the region where the Earth's magnetic field is very low like the SAA region it shows a tendency to be persistent.

scholarly journals Characterization of the South Atlantic Anomaly

2018 ◽  
Author(s):  
Khairul Afifi Nasuddin ◽  
Mardina Abdullah ◽  
Nurul Shazana Abdul Hamid
Keyword(s):  
Magnetic Field ◽  
Geomagnetic Storm ◽  
South Atlantic ◽  
Active Period ◽  
The South ◽  
South Atlantic Anomaly ◽  
The Earth ◽  
Normal Period ◽  
Earth Magnetic Field ◽  
Latitude Region

Abstract. This research intends to characterize the South Atlantic Anomaly (SAA) by applying power spectrum analysis approach. From the approach, the Hurst exponent can be determined. The motivation to study the SAA region is due to its nature. A comparison was made between the stations in the SAA region and outside the SAA region during the geomagnetic storm occurrence (active period) and normal period where no geomagnetic storm occurred. The data for the occurrence of the active period was taken on 11 March 2011 while for normal period on 3 February 2011. The outcomes of the research revealed that the SAA region had a tendency to be persistent during active period and normal periods. It can be said, it experiences this characteristic because of the Earth’s magnetic field strength. Through the research, it is found that as the Earth magnetic field increases, it is likely to show an antipersistent value. This is found in the high latitude region. The lower the Earth magnetic field, the more it shows the persistent value as in the middle latitude region. In the region where the Earth magnetic field is very low like the SAA region it shows a tendency to be persistent.

scholarly journals Investigation on the characteristics of the South Atlantic Anomaly

2021 ◽  
Author(s):  
Khairul Afifi Nasuddin ◽  
Mardina Abdullah ◽  
Nurul Shazana Abdul Hamid
Keyword(s):  
Magnetic Field ◽  
High Latitude ◽  
Geomagnetic Storms ◽  
Middle Latitude ◽  
South Atlantic ◽  
The South ◽  
Earth’S Magnetic Field ◽  
South Atlantic Anomaly ◽  
High Latitude Region ◽  
Latitude Region

Abstract. The South Atlantic Anomaly (SAA) is known for its weak Earth’s magnetic field strength. In this research, power spectrum analysis method was applied on the Horizontal intensity of the Earth’s magnetic field with data sample rate used at 1 min. Four active periods on 18 March 2012, 10 March 2012, 25 April 2012, and 30 June 2013 which represent the occurrence of geomagnetic storms and 4 normal periods on 25 March 2012, 21 March 2012, 4 April 2012, and 15 June 2013 which indicate no geomagnetic storm event were examined. Research was conducted by analyzing the SAA region where comparisons were made between the middle latitude region and the high latitude region. The results indicate that the SAA region tends to be persistent, and this may be due to the ring current. The middle latitude region experienced a mixture of persistent and antipersistent characteristics and this may be due to the transportation of plasma and seasonal weather variations. The high latitude region tends to be antipersistent. This may indicate that the high latitude region is influenced by geomagnetic storms and the aurora.

scholarly journals Geomagnetic storm-time variations in the South Atlantic Anomaly Region

2005 ◽  
Author(s):  
Nalin B. Trivedi ◽  
Rajaram P. Kane ◽  
Severino L. G. Dutra ◽  
Nelson J. Schuch
Keyword(s):  
Geomagnetic Storm ◽  
South Atlantic ◽  
The South ◽  
South Atlantic Anomaly ◽  
Time Variations ◽  
Anomaly Region

Space Weather Effects on Proton Flux Variations in the South Atlantic Anomaly: A Numerical Study performed by Test Particle Simulations

2020 ◽  
Author(s):  
Kirolosse Girgis ◽  
Tohru Hada ◽  
Shuichi Matsukiyo
Keyword(s):  
Geomagnetic Storm ◽  
Space Weather ◽  
Test Particle ◽  
Three Dimensional ◽  
South Atlantic ◽  
Proton Flux ◽  
Storm Event ◽  
Time Varying ◽  
The South ◽  
South Atlantic Anomaly

<p>In this study, we assess the hourly variations of the three-dimensional proton flux distribution inside the South Atlantic Anomaly (SAA) during a geomagnetic storm. We have developed a relativistic three-dimensional guiding center test particle simulation code in order to compute the proton trajectories in a time-varying magnetic field background provided by Tsyganenko model TS05 and the corresponding time-varying inductive electric field. The Dst index is the main input parameter to the simulation model, while the maximum proton flux, the area of the SAA calculated below a selected threshold, and the penetration depth of the protons are the main output variables investigated in this study were. Since the LEO spacecraft and human-related activities are already affected by space weather conditions, the South Atlantic Anomaly (SAA) is also believed to create an additional source of risk. As the radiation environment depends essentially on the particle flux, the objective of this study is to estimate quantitatively the proton flux variations inside the South Atlantic Anomaly (SAA) in quiet and in storm conditions. So far, it was found that after several drift periods, the protons in the South Atlantic Anomaly (SAA) could penetrate to lower altitudes during geomagnetic storm event, and that, the SAA maximum flux value and the corresponding area, varied differently with respect to altitudes. Numerical results were compared with observations by NOAA 17 and RD3R2 instrument mounted on International Space Station (ISS).</p>

Broad-scale magnetic anomalies over central and eastern Canada: a discussion

1981 ◽  
Vol 18 (3) ◽  
pp. 657-661 ◽  
Author(s):  
R. L. Coles ◽  
G. V. Haines ◽  
W. Hannaford
Keyword(s):  
Magnetic Field ◽  
Sea Level ◽  
Vertical Component ◽  
Magnetic Anomalies ◽  
Superior Province ◽  
The South ◽  
Earth’S Magnetic Field ◽  
Eastern Canada ◽  
Earth's Magnetic Field ◽  
Broad Scale

Profiles of anomalies in the vertical component of the Earth's magnetic field over central and eastern Canada, observed at an average altitude of 4 km above sea level, show broad regions with distinctive anomaly character. These subdivisions indicate major differences in the evolutions of regions within individual structural provinces. Particularly notable is a region of intense anomalies in the northern part of the Superior Province in Quebec, contrasting with much weaker anomaly relief to the south and east.

scholarly journals Inner Radiation Belt Simulations of the Proton Flux Response in the South Atlantic Anomaly during the Geomagnetic Storm of 15 May 2005

2021 ◽  
Author(s):  
Kirolosse Mina Georges Zaki Girgis ◽  
Tohru Hada ◽  
Shuichi Matsukiyo ◽  
Akimasa Yoshikawa
Keyword(s):  
Geomagnetic Storm ◽  
Weather Conditions ◽  
South Atlantic ◽  
Low Earth Orbit ◽  
Proton Flux ◽  
Particle Simulation ◽  
The South ◽  
Simulation Code ◽  
South Atlantic Anomaly ◽  
Flux Response

A test particle simulation code was developed to simulate the inner proton belt response during the intense geomagnetic storm of May 15, 2005. The guiding center model was implemented in order to compute the proton trajectories with energy range 70-180 MeV. The time-varying magnetic field model implemented in the simulations was computed by the Tsyganenko model TS05 with the associated inductive electric field. One of the most important features of the Low-Earth Orbit (LEO) environment is the presence of the South Atlantic Anomaly, which imposes a dangerous radiation load on most of the LEO missions. The objective of this research is to investigate the proton flux variations in the anomaly region with respect to space weather conditions. The results showed that during the main phase of the geomagnetic storm, the proton flux in the SAA was decreased, whereas throughout the initial and recovery phases, the proton flux was increased at most of the altitudes. Numerical results were confirmed by satellite measurements.

scholarly journals The Mag.num core field model as a parent for IGRF-13, and the recent evolution of the South Atlantic Anomaly

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
M. Rother ◽  
M. Korte ◽  
A. Morschhauser ◽  
F. Vervelidou ◽  
J. Matzka ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Secular Variation ◽  
Field Model ◽  
South Atlantic ◽  
Model Parameters ◽  
The South ◽  
South Atlantic Anomaly ◽  
Core Field ◽  
The Core ◽  
Observatory Data

AbstractWe present the GFZ candidate field models for the $$13{\mathrm{th}}$$ 13 th  Generation International Geomagnetic Reference Field (IGRF-13). These candidates were derived from the geomagnetic core field model, which is constrained by Swarm satellite and ground observatory data from November 2013 to August 2019. Data were selected from magnetically quiet periods, and the model parameters have been obtained using an iteratively reweighted inversion scheme approximating a robust modified Huber norm as a measure of misfit. The root mean square misfit of the model to Swarm and observatory data is in the order of 3–5 nT for mid and low latitudes, with a maximum of 44 nT for the satellite east component data at high latitudes. The time-varying core field is described by order 6 splines and spherical harmonic coefficients up to degree and order 20. We note that the temporal variation of the core field component of the model is strongly damped and shows a smooth secular variation that suits well for the IGRF, where secular variation is represented as constant over 5-year intervals. Further, the external field is parameterised by a slowly varying part and a more rapidly varying part controlled by magnetic activity and interplanetary magnetic field proxies. Additionally, the Euler angles of the magnetic field sensor orientation are co-estimated. A widely discussed feature of the geomagnetic field is the South Atlantic Anomaly, a zone of weak and decreasing field strength stretching from southern Africa over to South America. The IGRF and indicate that the anomaly has developed a second, less pronounced eastern minimum at Earth’s surface since 2007. We observe that while the strong western minimum continues to drift westwards, the less pronounced eastern minimum currently drifts eastward at Earth’s surface. This does not seem to be linked to any eastward motion at the core–mantle boundary, but rather to intensity changes of westward drifting flux patches contributing to the observed surface field. Also, we report a sudden change in the secular variation measured at two South Atlantic observatories around 2015.0, which occurred shortly after the well-known jerk of 2014.0.

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