科研之友
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摘要
The Communications/Navigation Outage Forecasting System (C/NOFS) satellite observed large-scale density depletions at postmidnight and early morning local times in the Northern Hemisphere summer during solar minimum conditions. Using electric field data obtained from the vector electric field instrument (VEFI) as input, the assimilative physics-based model (PBMOD) qualitatively reproduced more than 70% of the large-scale density depletions observed by the Planar Langmuir Probe (PLP) onboard C/NOFS. In contrast, the use of a climatological specification of plasma drifts in the model produces no plasma depletions at night. Results from a one-month statistical study, we found that the large-scale depletion structures most often occur near longitudes of 60 degrees, 140 degrees, and 330 degrees, suggesting that these depletions may be associated with nonmigrating atmospheric tides, although the generation mechanisms of eastward electric fields at postmidnight local times are still uncertain. In this paper, densities obtained from both assimilation and climatology for the entire month of June 2008 are compared with PLP data from C/NOFS and the Challenging Minisatellite Payload (CHAMP), as well as special sensor ionospheric plasma drift/scintillation meter (SSIES) measurements from the Defense Meteorological Satellite Program (DMSP) satellites. Our statistical study has shown that, on average, the densities obtained by the PBMOD when it assimilates VEFI electric fields agree better with observed background densities than when PBMOD uses climatological electric fields.
- 出版日期2011-9-22
