HR: 09:50h
AN: SA41A-07 [Abstracts]
TI: Twilight Observations of Thermospheric Atomic Oxygen Density during Magnetic Storms
AU: Rogan, T
EM: john.meriwether@ces.clemson.edu
AF: Clemson University, Department of Physics and Astronomy
208 Kinard Laboratory, Clemson, SC 29634-0978
United States
AU: * Meriwether, J W
EM: john.meriwether@ces.clemson.edu
AF: Clemson University, Department of Physics and Astronomy
208 Kinard Laboratory, Clemson, SC 29634-0978
United States
AU: Brown, L B
EM: bailesb@yahoo.com
AF: Clemson University, Department of Physics and Astronomy
208 Kinard Laboratory, Clemson, SC 29634-0978
United States
AB:
Fabry-Perot interferometer (FPI) observations of the 732-nm doublet emission during evening and morning twilights have been
made regularly at Arequipa, Peru (16.5 S, 71.4 W) since April, 2005. Arequipa is a site located 4 degrees south of the
magnetic equator. Excitation of this emission is a result of the EUV photoionization of [O] to generate the 2P metastable
state of O+. Variation of this emission intensity during twilight occurs as the twilight terminator passes through the
thermosphere during evening or morning twilights. Consequently, the 732-nm emission intensity is proportional to the [O]
abundance illuminated by the Sun along the line-of-sight path from the Arequipa FPI through the thermosphere. Contamination
of the FPI spectra by OH mesospheric emissons does appear but can be treated by appropriate scaling and subtraction of the OH
emission spectrum. These twilight profiles can be compared with model predictions based upon the MSIS-00 empirical model,
and absolute thermospheric [O] densities can be retrieved by comparison with the model predictions. Examination of these
twilight profiles during periods of magnetic storm activity will show how the thermospheric [O] density responds to the
initiation and recovery of the magnetic storm, and several examples of such behavior will be presented.
DE: 0310 Airglow and aurora
DE: 0355 Thermosphere: composition and chemistry
DE: 0360 Radiation: transmission and scattering
SC: SPA-Aeronomy [SA]
MN: Fall Meeting 2005