AbstractThe Space Environment Monitor (SEM) onboard the NOAA POES satellites has been measuring the near-Earth charged particle environment since 1978, providing an extensive database that can be used for studying the long-term behavior of this population of trapped particles. POES stands for Polar Orbiting Environmental Satellite. These satellites orbit at ∼840km altitude and at an inclination of 98°. The SEM-1 instrument was flown on the POES satellites beginning in 1978 with TIROS-N and NOAA-6 in 1979 and continuing to NOAA-14 launched in 1995 with the exception of NOAA-9 and NOAA-11 (NOAA-13 failed shortly after launch). Its replacement, SEM-2, has flown on the POES NOAA-15, -16, and -17 satellites (from 1998). Here we present the results of a study on the statistical variations of the high-energy trapped proton environment. Among the detectors in SEM, the four SEM-2 omni-directional proton detectors for energies >16MeV, >36MeV, >70MeV, and >140MeV provide the data most relevant to this study.For this study, the SEM-2 omni-directional detector data from each satellite (NOAA-15, -16, and -17) were accumulated over 8-s intervals and arranged/collected on a 1° latitude by 2° longitude grid. The data set covers the period between June 1, 1998 and June 30, 2005. This amounts to about 15 satellite-years of data encompassing much of a solar cycle. The spatial grid covers sub-satellite locations at latitude center values from 65.5° north to 72.5° south and longitude center values from 1° east to 359° east. Typically there are 1700–2100 individual data entries per detector within each longitude–latitude bin. For each spatial bin, we also computed for detailed analysis various geomagnetic field parameters (e.g., McIlwain’s L value, local field strength, field strength at the equator along the field line, etc.) for the field line threading the center of the bin. For this purpose, we used the International Geomagnetic Reference Field (IGRF) Model, Epoch 2003.5. Each data sample within the spatial bin also contains the information on geomagnetic activity and an index indicating whether a Solar Energetic Particle (SEP) event was in progress at the time the data were taken and the magnitude of that event. The final data set thus obtained forms an extensive source of information useful for studying the long-term near-Earth trapped proton environment as a function of solar cycle, magnetic activity and the role of SEP events.


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    Titel :

    Long-term observations of the trapped high-energy proton population (L<4) by the NOAA Polar Orbiting Environmental Satellites (POES)


    Beteiligte:
    Evans, D. (Autor:in) / Garrett, H. (Autor:in) / Jun, I. (Autor:in) / Evans, R. (Autor:in) / Chow, J. (Autor:in)

    Erschienen in:

    Advances in Space Research ; 41 , 8 ; 1261-1268


    Erscheinungsdatum :

    2007-11-17


    Format / Umfang :

    8 pages




    Medientyp :

    Aufsatz (Zeitschrift)


    Format :

    Elektronische Ressource


    Sprache :

    Englisch