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Dynamics and Photochemistry of N2+ Ion in the Polar Ionosphere

Dynamics and Photochemistry of N2+ Ion in the Polar Ionosphere. Manabu Yamada, S. Watanabe （ Hokkaido Univ. ） N. Yoshida, Y. Takahashi （ Tohoku Univ. ） Y. Ogawa and R. Fujii （ STEL, Nagoya Univ. ）. In situ observation DE1 satellite, Akebono satellite, etc. Optical observation

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Dynamics and Photochemistry of N2+ Ion in the Polar Ionosphere

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  1. Dynamics and Photochemistry of N2+ Ion in the Polar Ionosphere Manabu Yamada, S. Watanabe （Hokkaido Univ.） N. Yoshida, Y. Takahashi（Tohoku Univ.） Y. Ogawa and R. Fujii （STEL, Nagoya Univ.）

  2. In situ observation DE1 satellite, Akebono satellite, etc. Optical observation MSX satellite Molecular Ions observed by satellites Molecular ions were observed at high altitudes of several thousands km. DE1 satellite observed molecular ions at several RE. (Craven et al., 1985)

  3. Why molecular ions exist at several thousands km altitudes? • Where is the source? (Altitude, MLT) • How to move from low altitudes? • There are methods to observe ions near 1000 km altitudes where ions are heated/accelerated. • Rocket/Satellite． • Radar : It is difficult to identify ion species．

  4. Possibility of N２+ ground based observation. • Romick et al. [1999] • Using MSX satellite, they observed solar resonance fluorescence of N2+ ion above 450 km at the Northern polar cap. Romick et al. [1999]

  5. A new method of ion upflow observation • Optical ground based observation of N2+ 1st negative bands resonant scattering. • We may monitor cusp structure. • We may understand structure of ion heating/acceleration region and mechanisms of molecular ion upflow.

  6. Period: 25 Nov. 2000～9 Dec. 2000 Location: Longyearbyen Auroral station Geographic coordinate 78ﾟ,12′,086″N,15ﾟ,49′,893″E Invariant latitude 75ﾟ18′N Observation List of all observation MLT =UT+4.09 [hour] =LT+3.02 [hour]

  7. observation 2000/11/28- observation 2000/12/01-

  8. Simultaneous observation of 2 wave lengths(6 channels) 427.8nm (N2+1st negative) 557.7nm (OI) Exposure: 1min. MAIS （Multicolor All-sky Imaging System）

  9. Estimation of altitude profile • Assumption • 557.7nm and 427.8nm are emitted at same magnetic field line. • The peak of 557.7nm emission is 110km. ③ Calculation • Pick up geomagnetic meridian data. • Estimate the distance until the aurora using a peak of 557.7 emission. • Obtain altitude profile of N2+ emission. 110km Θpeak ② B ①

  10. T1 Estimation of N2+ produced by EUV To estimate intensity profile of N2+ emission. • From data obtained at day time, we can know relation between solar zenith angle and intensity at the zenith. • To differentiate the data, intensities of N2+ emission at each altitude are estimated. T２ Intensity of N2+ emission decreases 4 order with the increase of altitudes from 100km to 200km.

  11. Summary • N2+ 1st negative bands emission at several hundred km altitudes in aurora region could be observed from ground. • We may be able to monitor ion dynamics in the topside ionosphere using N2+ 1st negativebands emission. To observe N2+ emission in the cusp region • Improve method of analysis and instrument of observation.

  12. Acknowledgements • We are indebted to the director and staff of EISCAT for operating the facility and supplying the data. EISCAT is an International Association supported by Finland (SA), France (CNRS), the Federal Republic of Germany (MPG), Japan (NIPR), Norway (NFR), Sweden (NFR) and the United Kingdom (PPARC).

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