Indo-German low-latitude project deos: plasma bubbles in the post sunset and nighttime sector |
| |
Institution: | 1. Graduate School of Environmental Studies, Tohoku University, 980-8579 Sendai, Japan;2. Research Institute for Marine Geodynamics, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka 237-0061, Japan |
| |
Abstract: | Two spread-F flights were performed under equinox conditions in April and September 1998 from the Indian low-latitude station SHAR. Both flights detected plasma bubbles confined to a narrow longitudinal extent. Plasma parameters are measured under two different conditions in the post-sunset ionosphere; when the F-layer is moving upward (19:21 IST launch) and when the F-layer is stationary (20:41 IST launch). Low altitude bubbles during upwelling of the F-region in the prereversal current enhancement phase are characterized by turbulent, non Maxwellian regions. Transitional scale waves with k=−3.6 are observed in the bubbles. This flight also detects strong sharp E-layers during downleg and an intermediate layer at 170km. Nighttime bubbles during almost stationary F-layer conditions show turbulent, Maxwellian features with moderate cooling compared to the undisturbed environment. Transitional scale waves in the bubble region show a spectral index k=−3.1. The spectral power is reduced by around 20dB compared to the sunset flight. |
| |
Keywords: | |
本文献已被 ScienceDirect 等数据库收录! |
|