HR: 0830h
AN: SA21B-0065    [PDF]
TI: Ion temperature climate in the polar ionosphere using incoherent-scatter radars
AU: * Oyama, S
EM: soyama@gi.alaska.edu
AF: Geophysical Institute University of Alaska Fairbanks, 903 Koyukuk Drive P.O. Box 757320, Fairbanks, AK 99775-7320 United States
AU: Lathuillere, C
EM: Chantal.Lathuillere@obs.ujf-grenoble.fr
AF: Laboratoire de Planetologie de Grenoble, Batiment D de Physique, BP 53, Grenoble, 38041 France
AU: Maeda, S
EM: smaeda@kyoto-wu.ac.jp
AF: Kyoto Women's University, 35 Kita-Hiyoshi Imakumano, Higashiyama, Kyoto, 605-8501 Japan
AU: Watkins, B J
EM: ffbjw@uaf.edu
AF: Geophysical Institute University of Alaska Fairbanks, 903 Koyukuk Drive P.O. Box 757320, Fairbanks, AK 99775-7320 United States
AB: We focus on seasonal and solar activity dependences of the ion temperature in the polar ionosphere using data from several incoherent scatter-radars (ISR): the Sondrestrom ISR ($67\deg$N, $309\deg$E, $74\deg$ magnetic latitude), the European Incoherent Scatter (EISCAT) UHF Troms{\o} radar ($69\deg$N, $19\deg$E, $66\deg$ magnetic latitude), and the EISCAT Svalbard radar (ESR: $78\deg$N, $16\deg$E, $75\deg$ magnetic latitude). Since these radars are located at different magnetic latitudes, we can estimate the meridional structure of ion temperature from the statistical results calculated using long-term data sets. Below about 300 km, the energy transfer from neutrals to ions plays a significant role than that from electrons because the ion-neutral collision frequency is much higher than the ion-electron collision frequency for this height region. While studies of neutral temperature using the ion temperature data from ISRs have been conducted for more than two decades, the relationship between the ion and neutral temperatures is not well known at high latitudes because of recurrent joule energy dissipation. On the other hand, above 300 km the energy transfer from electrons through collisions becomes important with increasing heights. The statistical results from the EISCAT Troms{\o} radar data for about one solar cycle show that for summer the ion temperature in the upper F-region has higher values at local night than at local noon, and for other seasons daytime values are higher than night values. Statistical results for the ESR data show not only summer, but also some other seasons, show higher temperatures at local night than at local noon in this height region. In the case of the Sondrestrom radar data, the ion temperatures at summer night are also higher than the daytime values. These characteristics are not in agreement with standard model profiles of the ion temperature. The different characteristics suggest that the ion temperature climate in the polar ionosphere should have the meridional structure, which might be associated with the auroral oval. We will show these differences as well as other climate of the ion temperature in more detail in the presentation.
DE: 2400 IONOSPHERE
DE: 2407 Auroral ionosphere (2704)
DE: 2431 Ionosphere/magnetosphere interactions (2736)
DE: 2455 Particle precipitation
DE: 2467 Plasma temperature and density
SC: SPA - Aeronomy [SA]
MN: 2003 Fall Meeting