Location
Yosemite National Park
Start Date
2-10-2014 9:30 AM
End Date
2-10-2014 10:00 AM
Description
Every day, the Earth looses a significant amount of mass through ions escaping from the polar ionosphere. Due to spacecraft charging effects and the very low escape energy of ions, in-situ measurements using traditional plasma instruments are typically not able to detect the cold component of the outflow. However, recent advances in instrumentation and methodology, combined with a comprehensive data set from the Cluster constellation of spacecraft have provided far better opportunities to assess the role of the low energy ions. In this study, we have utilized these advantages to determine the source region, transport mechanisms as well as the fate of low energy ions of ionospheric origin. The results suggest that the polar cap region is the primary source of cold outflow, but enhanced outflow from the cusp and auroral zone is observed during disturbed geomagnetic conditions. The transport of cold ions is mainly governed by the convection, and most of the outflowing ions are transported to the nightside plasma sheet. Direct loss along open field lines downtail into the solar wind only takes place during quiet magnetospheric conditions with low or stagnant convection.
Cold Ion Outflow from the Polar Cap Region: Cluster Results
Yosemite National Park
Every day, the Earth looses a significant amount of mass through ions escaping from the polar ionosphere. Due to spacecraft charging effects and the very low escape energy of ions, in-situ measurements using traditional plasma instruments are typically not able to detect the cold component of the outflow. However, recent advances in instrumentation and methodology, combined with a comprehensive data set from the Cluster constellation of spacecraft have provided far better opportunities to assess the role of the low energy ions. In this study, we have utilized these advantages to determine the source region, transport mechanisms as well as the fate of low energy ions of ionospheric origin. The results suggest that the polar cap region is the primary source of cold outflow, but enhanced outflow from the cusp and auroral zone is observed during disturbed geomagnetic conditions. The transport of cold ions is mainly governed by the convection, and most of the outflowing ions are transported to the nightside plasma sheet. Direct loss along open field lines downtail into the solar wind only takes place during quiet magnetospheric conditions with low or stagnant convection.