Defining the Most Hazardous Radiation Belt Enhancement Events Based on Probability Distributions
Abstract
In 2018 a broad range of US federal departments and agencies jointly published benchmarks for extreme space weather events and in 2019 a group of 32 leading space weather scientists published recommendations for next steps to further refine and improve those benchmarks. Among the recommendations was to specify hazardous events that might not be as extreme as the 1-in-100 year events.
We will present a statistical analysis based on ~30 years of relativistic electron fluxes (~2 MeV) at geosynchronous orbit that identifies events that occur on average 100 times per cycle, 10 times per cycle, and 1 time (where a `cycle' is an arbitrary 11-year time span). A significant advantage of using probability distributions is that heterogeneous data sets can be quantitatively compared. For example we can specify the flux thresholds in different data sets that give the same average event rate (N per cycle, N per decade, or N per year). The data sets can be in different units (e.g. flux and dose rate) or even different quantities (e.g. storms and radiation belt events). We will discuss how the event rate (for a given threshold) varies across the solar cycle and from one solar cycle to another. In addition we present a catalog of events that can be used for further statistical analysis including extreme value analysis using statistically independent "events" rather than statistically-dependent time series. Although we apply this methodology to the radiation belts, it is important to note that the same technique can be applied to a variety of space weather phenomena and is therefore quite general.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMSM050..07R
- Keywords:
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- 4313 Extreme events;
- NATURAL HAZARDS