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Ann. Geophys., 18, 1164-1171, 2000
www.ann-geophys.net/18/1164/2000/
© European Geosciences Union 2000
A self-consistent estimate of O+ + N2 − rate coefficient and total EUV solar flux with λ < 1050 Å using EISCAT observations
A. V. Mikhailov1 and K. Schlegel2
1Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Troitsk, Moscow Region 142092, Russia
2Max-Planck-Institute für Aeronomie, Max-Planck-Str. 2, D-37191 Katlenburg-Lindau, Germany
Abstract. There are differences between existing models
of solar EUV with λ < 1050 Å and between laboratory measurements
of the O+ + N2 – reaction rate coefficient, both
parameters being crucial for the F2-region modeling. Therefore, indirect
aeronomic estimates of these parameters may be useful for qualifying the
existing EUV models and the laboratory measured O+ + N2 –
rate coefficient. A modified self-consistent method for daytime F2-region
modeling developed by Mikhailov and Schlegel was applied to EISCAT observations
(32 quiet summer and equinoctial days) to estimate the set of main aeronomic
parameters. Three laboratory measured temperature dependencies for the O+
+ N2 – rate coefficient were used in our calculations to find
self-consistent factors both for this rate coefficient and for the solar EUV
flux model from Nusinov. Independent of the rate coefficient used, the
calculated values group around the temperature dependence recently measured by
Hierl et al. in the 850–1400 K temperature range. Therefore, this rate
coefficient may be considered as the most preferable and is recommended for
aeronomic calculations. The calculated EUV flux shows a somewhat steeper
dependence on solar activity than both, the Nusinov and the EUVAC models
predict. In practice both EUV models may be recommended for the F2-region
electron density calculations with the total EUV flux shifted by ±25% for the
EUVAC and Nusinov models, correspondingly.
Key words: Ionosphere (ion chemistry and composition;
ionosphere atmosphere interactions; modeling and forecasting)
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