Indo-German Low-Latitude Project DEOS: Plasma Bubbles in the Post Sunset and Nighttime Sector
Advances in Space Research
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.
Thiemann, H., J. J. Sojka, J. V. Eccles, P. B. Rao, P. V. S. Rama Rao, R. Sirdharan, and G. S. Lakhina, Indo-German low-latitude project DEOS: Plasma bubbles in the post sunset and nighttime sector, Adv. Space Res., 27, 1065-1069, 2001.