ROCSAT 1 ionospheric plasma and electrodynamics instrument observations of equatorial spread F: An early transitional scale result

Abstract

Abstract. Ion density and vertical ion drift velocity sampled at 1024 Hz from the ROCSAT 1 satellite are used to examine the behavior of horizontal structures in equatorial spread F near 600 km altitude. An initial investigation shows that at scale sizes less than 100 m the relationships between the vertical drift and density structure are distinguished by the bulk plasma flow in the structure and by the background gradient in the density. Two adjacent equatorial bubble structures are examined: one in which the bulk plasma flow is upward and characteristic of an active evolving bubble and the other in which the bulk plasma flow is small and characteristic of a stagnated structure. We find that at scale sizes less than 100 m the velocity structure has a spectral slope that is consistently shallower than that of the density structure in the stagnated bubble but matches closely the spectrum of the density structure in the active bubble. Each of the bubble regions examined are characterized by one edge that has a much larger background gradient than the other. We find that in these bubbles, observed near 600-km altitude, the lower background gradient is characterized by enhanced structure at 1-km scale sizes.

Relation of zonal plasma drift and wind in the equatorial F region as derived from CHAMP observations

“…Its orbital altitude is 600 km, and the inclination angle is about 35 • (e.g. Su et al, 2001). Note that the orbit altitude is higher than that of CHAMP.…”

Equatorial Atmosphere Radar (EAR): System description and first results

“…High-resolution observations with the EAR, never before realized, must play an important role in various studies of the equatorial atmosphere and ionosphere. It is expected that the EAR will be operated in collaboration with other existing networks of radars, such as those mentioned in the Introduction, satellites such as TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics) of the USA and ROCSAT-1 of the Republic of China (Taiwan) [Su et al, 2001], and other ground-based radio and optical sensors. The EAR is expected to proceed to study the hierarchical structure of atmospheric variations in the equatorial region using the data from these instruments in the future.…”

The effects of the pre-reversal ExB drift, the EIA asymmetry, and magnetic activity on the equatorial spread F during solar maximum

“…The ESF studies using ionosonde data (Sales et al, 1996;Stephan et al, 2002;Whalen, 2002), the Global Positioning System (GPS) (Aarons et al, 1996;Mendillo et al, 2000Mendillo et al, , 2001, radars (Woodman and LaHoz, 1976;Hysell and Burcham, 1998), satellite (Huang et al, 2001;Su et al, 2001), and numerical modeling (Maruyama, 1988;Sultan, 1996) have demonstrated the general morphology of the ESF phenomenon. Now, it is known that there are some candidate mechanisms helping the ESF development.…”