Dynamics Explorer 2 satellite observations and satellite track model calculations in the cusp/cleft region
- Univ. of Michigan, Ann Arbor, MI (United States); and others
The authors present two detailed cases of the ionospheric and thermospheric response to soft particle precipitation in the cusp/cleft region using multi-instrument observations from the Dynamics Explorer 2 (DE 2) satellite during orbits 688 and 748, together with supporting model calculations. The experimental data set is among the most comprehensive reported to date and includes a specification of both soft particle input to the atmosphere and the detailed local atmospheric response to these inputs. Specifically, observations are presented of precipitating ion and electron fluxes, ion and neutral horizontal and vertical wind speeds, neutral temperatures and densities, and volume emission rates for the O I 630.0 nm red line, which is often used as a themospheric signature of soft electron precipitation. The two orbits were chosen to provide represenative cases for active (orbit 688; Kp=5; interplanetary magnetic field (IMF) B{sub z}=0.5nT) and quiet (orbit 748; Kp=1; IMF Bz=+7.8 nT) geomagnetic conditions. Some of the data were used to provide boundary conditions and inputs to a satellite track code that was used to calculate the ionospheric structure below and along the orbital track. The satellite track code enables the authors to calculate the Joule- and particle-heating altitude profiles and the ionization rate altitude profile. During each of the two orbits the region of soft electron precipitation associated with the cusp/cleft region was clearly identifiable. Several principal findings of this study are as follows: (1) The maxima in the cusp/cleft soft electron (<100 eV) precipitating flux were {approx} 3 x10{sup {minus}3} and {approx} 5 x 10{sup {minus}4}ergs/(cm{sup 2}s sr eV) for orbits 688 and 748 respectively. (2) The calculated ionization rate peaked at an altitude near 265 km, or 60 km lower than the altitude of the enhancement in the 630.0-nm volume emission rate. 41 refs., 8 figs., 1 tab.
- OSTI ID:
- 255053
- Journal Information:
- Journal of Geophysical Research, Vol. 101, Issue A3; Other Information: PBD: 1 Mar 1996
- Country of Publication:
- United States
- Language:
- English
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