HR: 1400h
AN: SA33A-10    [Abstracts]
TI: Thermospheric Nitric Oxide at Higher Latitudes - Model Calculations With Auroral Energy Input
AU: Sætre, C
EM: camilla.saetre@ift.uib.no
AF: Department of Physics and Technology, University of Bergen, Postboks 7803, Bergen, 7803, Norway
AU: Barth, C A
AF: Laboratory for Atmospheric and Space Physics, University of Colorado, 1234 Innovation Drive, Boulder, CO 80303-7814, United States
AU: * Stadsnes, J
EM: johan.stadsnes@ift.uib.no
AF: Department of Physics and Technology, University of Bergen, Postboks 7803, Bergen, 7803, Norway
AU: Østgaard, N
AF: Department of Physics and Technology, University of Bergen, Postboks 7803, Bergen, 7803, Norway
AU: Bailey, S M
AF: Geophysical Institute, University of Alaska, 903 Koyukuk Dr., Fairbanks, AK 99775-7320, United States
AU: Baker, D N
AF: Laboratory for Atmospheric and Space Physics, University of Colorado, 1234 Innovation Drive, Boulder, CO 80303-7814, United States
AU: Germany, G A
AF: Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, 5131 Technology Hall, Huntsville, AL 35899, United States
AU: Gjerloev, J W
AF: Applied Physics Laboratory, Johns Hopkins University, 11100 Johns Hopkins Road, Laurel, MD 20723-6099, United States
AB: The nitric oxide (NO) density in the lower thermosphere has been calculated by a photochemical model for NOx and compared with measured NO densities. At higher latitudes the most important contributor for NO density increases is energetic electron precipitation. The electron energy input is divided into geographic areas of 5° latitude and 24° longitude for a continuous time interval of four days. The energy is estimated in two ways; from auroral ultraviolet (UV) and X-ray measurements, and from ground magnetometer measurements. These are used as input for the photochemical NOx model. The UV and X-ray measurements are from the Ultraviolet Imager (UVI) and the Polar Ionospheric X-ray Imaging Experiment (PIXIE), both on the Polar spacecraft. For the time intervals without UVI and PIXIE measurements, a parametrization of the electron energy flux from ground magnetic measurements was used. This parametrization was based on data from the SuperMAG database compared to UVI/PIXIE derived electron energy fluxes. The negative perturbation in the northward ground magnetic component is found to be linearly related to the precipitating electron energy flux derived from UVI and PIXIE measurements. The four day period studied is from 30 April until 4 May 1998, where the onset of a geomagnetic storm occurred 2 May (day 122). The modelled NO density is compared with NO measurements from the Student Nitric Oxide Explorer (SNOE). The results show an overall larger modelled nitric oxide density at auroral latitudes than what was measured by SNOE. The largest discrepancies were for the day of the storm onset, when the background atmosphere was most distorted by Joule heating. The next day, when the atmosphere had settled down, the agreement between the model and the observations was far better.
DE: 0355 Thermosphere: composition and chemistry
DE: 2451 Particle acceleration
DE: 3369 Thermospheric dynamics (0358)
SC: SPA-Aeronomy [SA]
MN: 2007 Joint Assembly