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Persistent URL http://purl.org/net/epubs/work/36655
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Record Id 36655
Title Report on the solar protons events model
Abstract This document presents the results of SEDAT work package 301, which is a demonstration of the application of SEDAT to analyse solar proton events. Section 3 (Solar proton datasets) describes the solar proton flux datasets used in this work and outlines the techniques used to convert these to fluences, e.g. interpolation over data gaps. Section 4 (Solar proton event detection) describes the work that was done to develop a tool to detect solar proton datasets. It first describes the two smoothing techniques that were adapted from image processing techniques and compares their ability to process solar proton data, which leads to the selection of median filtering as the preferred method because of its robust rejection of noise spikes. It then describes event detection by application of a threshold to the smoothed proton data. Section 5 (Manipulation of event files) describes the event files produced by the event detector. These have a well-defined record format and good metadata in order to support their subsequent manipulation and processing. The internal SEDAT data structure for these events records is also described. This section then discusses some of the tools developed to examine, edit and merge event files prior to processing by other tools. Finally we discuss the ingestion into SEDAT of historical proton event data (1956 to 1985) as supplied by ESTEC. Section 6 (Using and updating the JPL-91 model) first discusses a key aspect of the JPL-91 model - namely the fitting of event fluence distributions to a log-normal form and the derivation of the mean and standard deviation of that form. The special display format used to linearise the log-normal distribution is discussed in detail and an example(s) of its application within SEDAT is presented. This second then discusses the implementation of the JPL-91 model within SEDAT. This follows the approach given in R1 and R2 (it proved useful to read both papers). The detailed implementation is discussed in some detail including the use of built-in IDL functions to generate normally-distributed pseudo-random numbers and the parallel calculation of probabilities for different fluence thresholds (following a suggestion from ESTEC). The result of the SEDAT implementation are compared with those in the literature and shown to be in good agreement. Section 7 (Statistical sampling of the fluence distribution) discusses the direct generation of percentiles of the fluence distribution for comparison with the results of the JPL-91 model. In this section we discuss the pseudo-random sampling of a time series of accumulating fluence to derive a set of the different fluences that can accumulated over a given duration. This set can then be analysed to derive the percentiles of the fluence distribution. By plotting percentages against the equivalent percentiles we obtain a direct plot of probability versus fluence. Several examples of these plots are presented. Section 8 (Comparison of percentile plots with the JPL-91 model) shows how we can compare the direct plot of probability versus fluence obtained in section 7 with the equivalent results of the JPL-91 model. Section 9 presents overall conclusions to the report including some caveats and ideas for follow-up work.
Organisation CCLRC , SSTD
Keywords Physics , space weather , solar protons
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Language English (EN)
Type Details URI(s) Local file(s) Year
Report Report on the solar protons events model, RAL-SED-RP-0301. wp301_report_v8.pdf 2004
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