Photoelectron impact excitation of OI 8446 Å emission observed from Arecibo Observatory

Details Photoelectron impact excitation of OI 8446 Å emission observed from Arecibo Observatory Photoelectron impact excitation of OI 8446 Å emission observed from Arecibo Observatory

Jan 2008

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008jgra..11301303w&link_type=abstract

Journal of Geophysical Research, Volume 113, Issue A1, CiteID A01303

Physics

3

Atmospheric Composition And Structure: Airglow And Aurora, Atmospheric Composition And Structure: Thermosphere: Composition And Chemistry, Ionosphere: Ionosphere/Atmosphere Interactions (0335), Atmospheric Composition And Structure: General Or Miscellaneous

Scientific paper

Photoelectron (PE) impact on thermospheric oxygen atoms is a major source of OI 8446 Å emission excitation at midlatitudes. However, historical discrepancies between observed twilight emission brightnesses and PE model predictions have not only prompted speculation regarding secondary sources of excitation but also precluded the use of observed brightness as a much-needed diagnostic of thermospheric O density. In an effort to improve understanding of the physical mechanisms responsible for its excitation, this paper presents new photometric measurements of twilight OI 8446 Å emission brightness, together with calculations using the Field Line Interhemispheric Plasma (FLIP) PE model, acquired from Arecibo Observatory under geomagnetically quiet conditions during three winter campaigns from 1999-2002. Winter is a particularly favorable season for twilight 8446 Å observation in the northern hemisphere since significant PE production, and thus 8446 Å excitation, persists for several hours in the fully illuminated, geomagnetic conjugate hemisphere in the absence of any local thermospheric illumination. The winter 8446 Å brightness data are fully consistent with a dominant PE impact excitation source. However, the new data also confirm the Lancaster et al. (2000) report of excess early morning brightness at Arecibo with respect to PE models which use a tilted-dipole approximation to the geomagnetic field. By using the International Geomagnetic Reference Field (IGRF) geomagnetic field model to refine Arecibo's conjugate point location specified in the FLIP PE model, we demonstrate significantly improved agreement between the modeled and observed brightness decay profiles during both morning and evening twilight intervals.

Affiliated with

Also associated with

No associations

Rating

Photoelectron impact excitation of OI 8446 Å emission observed from Arecibo Observatory does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Photoelectron impact excitation of OI 8446 Å emission observed from Arecibo Observatory, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Photoelectron impact excitation of OI 8446 Å emission observed from Arecibo Observatory will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-897979