التفاصيل البيبلوغرافية
| العنوان: |
South Atlantic Anomaly Evolution Seen by the Proton Flux. |
| المؤلفون: |
Ginisty, F., Wrobel, F., Ecoffet, R., Mandea, M., Michez, A., Balcon, N., Ruffenach, M., Mekki, J. |
| المصدر: |
Journal of Geophysical Research. Space Physics; Jun2024, Vol. 129 Issue 6, p1-16, 16p |
| مصطلحات موضوعية: |
LOW earth orbit satellites, COSMIC rays, SPACE environment, PROTONS, SOLAR activity, RADIATION belts, SOLAR cycle |
| مستخلص: |
The SEM‐2 (Space Environment Monitor‐2) instrument embedded on the NOAA‐15 Low Earth Orbit satellite provides measurements of trapped protons in the Van Allen inner belt from 1998 to nowadays. This continuous set of measurements enables us to study the dynamics of the South Atlantic Anomaly (SAA) over more than two solar cycles, particularly, its temporal evolution. We observe that the area of the SAA is anti‐correlated with the solar activity. Two physical processes explain this anticorrelation. First, the more the Sun is active the more it disables the cosmic rays to reach the Earth's magnetosphere and fill in the inner radiation belt with protons. Then, when the Sun is more active, the upper atmosphere is warmer and therefore absorbs more protons from the radiation belt. Then, we investigate the protons flux centroid of the SAA. The temporal evolution of its position, latitude and, longitude is studied over the same time interval (1998–2022). We notice that the latitude of the centroid is also anti‐correlated with the solar activity whereas the longitude seems absolutely independent. The temporal evolution of the position of the centroid shows a drift of the SAA. Indeed from 1998 to 2022 the SAA drifted of about 7° West. The SEM‐2 instrument measures flux for protons of different energies (16, 36, 70, and, 140 MeV). For each energy, the SAA dynamic has a similar trend but with different values. These differences are investigated and the results are discussed. Key Points: The SAA is studied from proton flux measurements values in the inner radiation belt collected during the 1998–2022 period by the SEM‐2 instrument embedded on the NOAA‐15 satelliteThe SAA drifts globally Northward with an anticorrelation of its latitude with the solar activity and 7° Westward over a 24‐years periodThe higher the energy of the protons, the farther north and west the SAA shifts [ABSTRACT FROM AUTHOR] |
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| قاعدة البيانات: |
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