How representative are Van Allen Probes results from extreme events point of view?
How representative are Van Allen Probes results from extreme events point of view?
Friday, 9 March 2018: 16:05
Longshot and Bogey (Hotel Quinta da Marinha)
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Abstract:
Since their launch in August 2012, the Van Allen Probes have been observing the dynamics of the radiation belts during the maximum and declining phase of solar cycle 24. They provided us inestimable new data to improve our knowledge of the dynamics of the radiation belts. However, as the current solar cycle is part of the less active ones from the Space Era, the question of the representativeness of the “so-called” extreme events of solar cycle 24 rises: how far can we extrapolate the Van Allen Probes results to other solar cycles and how are they representative of worst cases scenario?
For this purpose we conducted a detailed statistical analysis of extreme events using different datasets. First we tried to obtain the most general picture of extreme events characteristics using almost 150 years of aa index data, as a reference. We developed a time integrated index named Ca based on aa index and the characteristic response time of the radiation belts to better identified strong events, and correlated it with in-situ measurements. From Extreme Value Analysis (EVA), we then defined the 1-in-10, 1-in-50 and 1-in-100 years event. Finally we focused on how can missions based datasets be representative, depending on their launch date and lifetime using such an EVA method. In particular we will show how far the Van Allen Probes life period can be considered as representative of the history of the radiation belts.
For this purpose we conducted a detailed statistical analysis of extreme events using different datasets. First we tried to obtain the most general picture of extreme events characteristics using almost 150 years of aa index data, as a reference. We developed a time integrated index named Ca based on aa index and the characteristic response time of the radiation belts to better identified strong events, and correlated it with in-situ measurements. From Extreme Value Analysis (EVA), we then defined the 1-in-10, 1-in-50 and 1-in-100 years event. Finally we focused on how can missions based datasets be representative, depending on their launch date and lifetime using such an EVA method. In particular we will show how far the Van Allen Probes life period can be considered as representative of the history of the radiation belts.