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| Titel |
On the importance of the Local Interstellar Spectrum for the Solar Modulation Parameter |
| VerfasserIn |
Klaudia Herbst, Andreas Kopp, Bernd Heber, Friedhelm Steinhilber, Horst Fichtner, Klaus Scherer, Daniel Matthiä |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250040171
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| Zusammenfassung |
| This study compares several local interstellar proton spectra often used in literature. We show
that the modulation parameter Ï, which parametrizes the modulation of the local interstellar
spectrum (LIS) in the heliosphere, strongly depends on the LIS itself. Further we will show
that all studied LIS require individual Ï values to fit the differential proton fluxes measured at
1 AU by using measurements of the PAMELA instrument during the solar minimum in July
2006. Taking the LIS-dependency of the modulation parameter into account, we also derive
linear equations to convert Ï between the different LIS. The conversions used here are
afterwards applied to a long-term reconstruction of Ï derived from a record of the
cosmogenic radionuclide 10Be. For some LIS models occasionally negative Ï values
are obtained, a fact which is impossible from the physical point of view. Despite
non-heliospheric effects such as uncertainties in the geomagnetic field and climate
influences on the 10Be production, one possible reason may also be the choice of the
LIS. By using the derived LIS conversions, we show that the negative Ï values in
the reconstruction vanish for certain LIS. Thus, the reconstruction of Ï provides
the potential to derive the lower intensity limit of the LIS, keeping in mind that
first the non-heliospheric effects have to be completely removed from the data. |
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