Investigation on the characteristics of the South Atlantic Anomaly

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.

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Characterization of the South Atlantic Anomaly

Nonlinear Processes in Geophysics ◽

10.5194/npg-26-25-2019 ◽

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.

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Characterization of the South Atlantic Anomaly

10.5194/npg-2018-51 ◽

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.

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The Earth's magnetic field of the last centuries from the perspective of the Jequitinhonha and Mucuri river valleys: A natural observatory of the South Atlantic Anomaly in Brazil

Journal of South American Earth Sciences ◽

10.1016/j.jsames.2020.102984 ◽

2020 ◽

pp. 102984

Author(s):

Wilbor Poletti

Keyword(s):

Magnetic Field ◽

South Atlantic ◽

The South ◽

Earth’S Magnetic Field ◽

South Atlantic Anomaly ◽

Earth's Magnetic Field ◽

River Valleys

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

Earth Planets and Space ◽

10.1186/s40623-020-01277-0 ◽

2021 ◽

Vol 73 (1) ◽

Cited By ~ 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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Can Geomagnetic Storms Affect Stratospheric O3 and NOx in the South Atlantic Anomaly Zone?

Pure and Applied Geophysics ◽

10.1007/s00024-020-02633-7 ◽

2021 ◽

Author(s):

Marta M. Zossi ◽

Elda M. Zotto ◽

Gustavo A. Mansilla

Keyword(s):

Geomagnetic Storms ◽

South Atlantic ◽

The South ◽

South Atlantic Anomaly

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A Statistical Analysis of Plasma Bubbles Observed by Swarm Constellation during Different Types of Geomagnetic Storms

Universe ◽

10.3390/universe7040090 ◽

2021 ◽

Vol 7 (4) ◽

pp. 90

Author(s):

Fayrouz Hussien ◽

Essam Ghamry ◽

Adel Fathy

Keyword(s):

Electron Density ◽

Geomagnetic Storms ◽

South Atlantic ◽

High Altitudes ◽

The South ◽

South Atlantic Anomaly ◽

Plasma Bubbles ◽

Duration Time ◽

Different Types ◽

Swarm Mission

Based on the observations of Ionospheric Bubble Index (IBI) data from the Swarm mission, the characteristics of plasma bubbles are investigated during different types of geomagnetic storms recorded from 2014 to 2020. The geometrical constellation of the Swarm mission enabled us to investigate the altitudinal profile of the IBIs during different activity levels in a statistical mean. Results show that the majority of IBIs associated with moderate storms are observed at low altitudes and the probability of observing IBIs at high altitudes (Swarm-B) increases with the increase in storm level. This is confirmed by observing the F2 layer peak height (hmF2) during super storm events at larger altitudes using COSMIC data. The maximum number of IBIs is recorded within the South Atlantic Anomaly (SAA) region with a long duration time and tends to increase only during dusk time. Both the large duration time and number of IBIs over the South Atlantic Anomaly (SAA) suggest that the gradient in the electron density and the depression in the magnetic field are the main factors controlling IBI events. Also, the IBIs at high altitudes are larger at sunset and at low altitudes pre-midnight. In addition, the occurrence of IBIs is always larger in the northern hemisphere than in the southern hemisphere irrespective of the type of storm, as well as during the summer months. Moreover, there is no correlation between the duration time of IBIs and both the altitudinal observation of the IBIs and the storm type. Seasonal occurrence of IBIs is larger during equinoxes and vice versa during solstices irrespective of both the type of storm and the altitude of the satellite. The large number of IBIs during equinoxes agrees with the previous studies, which expect that the large electron density is a developer of steeper . Large occurrences of super storm IBIs observed within the pre-midnight during summer and at sunset during equinoxes are a novel observation that needs further investigation. Also, the majority of IBIs are observed a few hours after geomagnetic substorms, which reflects the role of the Disturbance Dynamo Electric Field (DDEF) as a main driver of IBIs.

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