Determining wind field and electric field by a barium release experiment in the ionosphere

Barium release experiment is an effective way to study the near-earth environment, in which artificial plasma cloud is created via ionization of neutral gases released from a rocket or a satellite. The first barium release experiment in China was success- fully carried out by a sounding rocket at a height of about 190 km on April 5, 2013. The observed barium cloud images show that the neutral cloud follows a damping motion, whose velocity decreases exponentially and finally tends towards the wind velocity of the background. But for the ion cloud, the motion is controlled mainly by the Lorentz force and a ExB drift happens This work is devoted to calculating the wind and electric field of the background by analyzing the observed images from dif- ferent stations. It turns out that the wind has a magnitude of 51.28 m/s, which is mainly in the northeast direction but also has an appreciable vertical component; the ion cloud has a drift velocity of 71.38 m/s, with a large vertical velocity component be- sides the horizontal components, then the electric field is obtained from the drift velocity as 2.49 mV/m. It is interesting that the wind field shows a better agreement with GITM model than the other empirical or theoretical models, and the GITM model can also give a good prediction for the ion velocity observed by us, which is consistent with the ISR observation at Jicamarca as well.

Cold plasma redistribution throughout geospace

The redistribution of the electrically charged cold plasma of ionospheric origin involves the equatorial,low,mid,auroral,and polar-latitude regions in a multi-step,system-wide process linking the regions of geospace.Observations with ground and space-based instruments characterize the geospace plume-regularly occurring channels of enhanced plasma density flowing at both ionospheric and magnetospheric altitudes.Convection in the SAPS channel transports the eroded material to the noontime cusp in the ionosphere and to the dayside magnetopause at high altitudes.As the fluxes of cold plume plasma traverse the cusp and enter the polar cap,they form the polar tongue of ionization.At the cusp the plume plasma provides a rich source of heavy ions for the magnetospheric injection and acceleration via the mechanisms operative on those field lines.

Meridional movement of northern and southern equatorial ionization anomaly crests in the East-Asian sector during 2002-2003SSW

The present paper investigates the asymmetrical variability of the location of the north and the south equatorial ionization anomaly(EIA) crests in the East-Asian sector,along with their association with simultaneous observations of equatorial electrojet(EEJ) strength,geomagnetic activity index,and solar flux index during the 2002-2003 sudden stratospheric wanning(SSW) event.Analysis of these observations indicates the existence of a large-scale quasi 16-day periodic meridional movement in both EIA crests,and also reveals a strong correlation between the quasi 16-day oscillation in geomagnetic latitudes of the EIA crest and EEJ strength.The latitude of the northern/southern EIA crest and the EEJ strength indicate that obvious synchronous periodic oscillations were in-phase in the northern and southern hemisphere when the SSW occurred.In addition,it is also found that both the EIA crest location and amplitude of the periodic movement of the EIA locations exhibit hemispheric asymmetry.The amplitude of the periodic movement of the EIA location in the southern hemisphere is larger than that of the northern hemisphere,and the southern EIA crest is further off from the equator than the north one.Understanding these asymmetries requires a combination of mechanisms that involve at least trans-equator meridional winds and the position of a sub-solar point;however,potential disturbances in neutral winds associated with the SSW may additionally complicate the equatorial ionospheric dynamics.