Radiation belts in the region of the South-Atlantic magnetic anomaly

Vernov, S. N.; Gorchakov, E. V.; Shavrin, P. I.; Sharvina, K. N.

doi:10.1007/bf00182684

Cited by 34 publications

(9 citation statements)

References 36 publications

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“…As a result the maximum of the anomaly is displaced towards a higher L value. This variation of L-shell population, together with the variation of the position of the minimum of the magnetic field intensity in these L-shells (Vernov et al, 1967;Gledhill, 1976), leads to the oscillation represented by the second mode. A 10 month phase lag was obtained when the time series was compared with the thermospheric density variation.…”

Section: The Second Mode: Bipolar Oscillation In the Location Of The mentioning

confidence: 98%

“…It is enlightening to describe the anomaly in this way, the interaction of charged particles with the main field can be considered in a dipole field geometry (though tilted and displaced from the Earth's centre). In this study we took advantage of this feature to construct a reference frame that gets rid of effects due to changes of the tilt and/or the centre of the main field dipole and concentrates on effects that can be explained using the well-known dynamics of charged particles trapped in a dipolar magnetic field (Vernov et al, 1967;Gledhill, 1976).…”

Section: Reference Framesmentioning

confidence: 99%

“…Due to the dipole offset towards the western Pacific, the inner Van Allen radiation belt gets closer to the Earth over the SAA region. This means that the mirror points where trapped particles bounce in their spiralling around field lines lie at much lower altitudes there than elsewhere (Vernov et al, 1967;Gledhill, 1976). The eccentric dipole is currently offset from the Earth's centre by about 550 km in a direction approximately 22 • N, 140 • E. This distance is steadily increasing and the location of the eccentric dipole centre is drifting in the westward direction and slightly northward.…”

Section: Introduction: the Particle Flux In The South Atlantic Anomalymentioning

confidence: 96%

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The South Atlantic Anomaly throughout the solar cycle

Domingos

Jault

Pais

et al. 2017

Earth and Planetary Science Letters

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The Sun-Earth's interaction is characterized by a highly dynamic electromagnetic environment, in which the magnetic field produced in the Earth's core plays an important role. One of the striking characteristics of the present geomagnetic field is denoted the South Atlantic Anomaly (SAA) where the total field intensity is unusually low and the flux of charged particles, trapped in the inner Van Allen radiation belts, is maximum. Here, we use, on one hand, a recent geomagnetic field model, CHAOS-6, and on the other hand, data provided by different platforms (satellites orbiting the Earth -POES NOAA for 1998 and CALIPSO for 2006. Evolution of the SAA particle flux can be seen as the result of two main effects, the secular variation of the Earth's core magnetic field and the modulation of the density of the inner radiation belts during the solar cycle, as a function of the L value that characterises the drift shell, where charged particles are trapped. To study the evolution of the particle flux anomaly, we rely on a Principal Component Analysis (PCA) of either POES particle flux or CALIOP dark noise. Analysed data are distributed on a geographical grid at satellite altitude, based on a L-shell reference frame constructed from the moving eccentric dipole. Changes in the main magnetic field are responsible for the observed westward drift. Three PCA modes account for the time evolution related to solar effects. Both the first and second modes have a good correlation with the thermospheric density, which varies in response to the solar cycle. The first mode represents the total intensity variation of the particle flux in the SAA, and the second the movement of the anomaly between different L-shells. The proposed analysis allows us to well recover the westward drift rate, as well as the latitudinal and longitudinal solar cycle oscillations, although the analysed data do not cover a complete (Hale) magnetic solar cycle (around 22 yr). Moreover, the developments made here would enable us to forecast the impact of the South Atlantic Anomaly on space weather. A model of the evolution of the eccentric dipole field (magnitude, offset and tilt) would suffice, together with a model for the solar cycle evolution.

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Section: The Second Mode: Bipolar Oscillation In the Location Of The mentioning

confidence: 98%

Section: Reference Framesmentioning

confidence: 99%

Section: Introduction: the Particle Flux In The South Atlantic Anomalymentioning

confidence: 96%

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The South Atlantic Anomaly throughout the solar cycle

Domingos

Jault

Pais

et al. 2017

Earth and Planetary Science Letters

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“…The DNB records extremely high radiance values when high energy particles present in the ionosphere impact on individual detectors. These are most prevalent in the South Atlantic Anomaly, a well-known disturbance in the Earth's ionosphere [16]. The noise hits also occur when the spacecraft flies through auroral zones.…”

Section: Spike Height Index (Shi)mentioning

confidence: 99%

Automatic Boat Identification System for VIIRS Low Light Imaging Data

Elvidge¹,

et al. 2015

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Abstract:The ability for satellite sensors to detect lit fishing boats has been known since the 1970s. However, the use of the observations has been limited by the lack of an automatic algorithm for reporting the location and brightness of offshore lighting features arising from boats. An examination of lit fishing boat features in Visible Infrared Imaging Radiometer Suite (VIIRS) day/night band (DNB) data indicates that the features are essentially spikes. We have developed a set of algorithms for automatic detection of spikes and characterization of the sharpness of spike features. A spike detection algorithm generates a list of candidate boat detections. A second algorithm measures the height of the spikes for the discard of ionospheric energetic particle detections and to rate boat detections as either strong or weak. A sharpness index is used to label boat detections that appear blurry due to the scattering of light by clouds. The candidate spikes are then filtered to remove features on land and gas flares. A validation study conducted using analyst selected boat detections found the automatic algorithm detected 99.3% of the reference pixel set. VIIRS boat detection data can provide fishery agencies with up-to-date information of fishing boat activity and changes in this activity in response to new regulations and enforcement regimes. The data can provide indications of illegal fishing activity in restricted areas and incursions across Exclusive Economic Zone (EEZ) boundaries. VIIRS boat detections occur widely offshore from East and Southeast Asia, South America and several other regions.

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“…In this study, a total magnetic field strength of 22700 nT is used as the threshold to define the SAA region. The presence of energetic particles over the region in the 320 ± 45 km altitude range was initially detected by one of the COSMOS satellites (Vernov et al 1967). On the other hand the magnetic field geometry renders the polar ionosphere accessible to energetic particles and is a major source of ionization in the high latitudes (Sergeev et al 1983;Lyons 1997).…”

Section: Introductionmentioning

confidence: 99%

Abnormal Signatures Recorded by FORMOSAT-2 and FORMOSAT-3 over South Atlantic Anomaly and Polar Region

Lee¹,

Rajesh²,

Chen³

et al. 2014

Terr. Atmos. Ocean. Sci.

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Computer systems onboard FORMOSAT-2 (F2) and FORMOSAT-3/COSMIC (F3/C) satellites often register abnormal signatures which are recorded as automatic reconfiguration orders (ARO) in F2, and reboot/reset (RBS) in F3/C. The ARO and RBS spatial distribution counts recorded since the launch of satellites is investigated to identify regions of anomalous events. Data from the star tracker onboard F2 and Tiny Ionosphere Photometer (TIP) onboard F3/C are also analyzed. The results show that the F2 ARO and F3/C RBS cluster over the SAA (South Atlantic Anomaly) region and also over the poles, which suggest that high energy particles bombarding the satellite electronics play an important role.

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Radiation belts in the region of the South-Atlantic magnetic anomaly

Cited by 34 publications

References 36 publications

The South Atlantic Anomaly throughout the solar cycle

The South Atlantic Anomaly throughout the solar cycle

Automatic Boat Identification System for VIIRS Low Light Imaging Data

Abnormal Signatures Recorded by FORMOSAT-2 and FORMOSAT-3 over South Atlantic Anomaly and Polar Region

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