EarthRef.org Reference Database (ERR)
Development and Maintenance by the EarthRef.org Database Team

Detailed Reference Information
Liemohn et al. 2002
Liemohn, M.W., Kozyra, J.U., Clauer, C.R., Khazanov, G.V. and Thomsen, M.F. (2002). Adiabatic energization in the ring current and its relation to other source and loss terms. Journal of Geophysical Research 107: doi: 10.1029/2001JA000243. issn: 0148-0227.

The influence of adiabatic energization and deenergization effects, caused by particle drift in radial distance, on ring current growth rates and loss lifetimes is investigated. Growth and loss rates from simulation results of four storms (5 June 1991, 15 May 1997, 19 October 1998, and 25 September 1998) are examined and compared against the y component of the solar wind electric field (Ey,sw). Energy change rates with and without the inclusion of adiabatic energy changes are considered to isolate the influence of this mechanism in governing changes of ring current strength. It is found that the influence of adiabatic drift effects on the energy change rates is very large when energization and deenergization are considered separately as gain and loss mechanisms, often about an order of magnitude larger than all other source or loss terms combined. This is true not only during storm times, when the open drift path configuration of the hot ions dominates the physics of the ring current, but also during quiet times, when the small oscillation in L of the closed trajectories creates a large source and loss of energy each drift orbit. However, the net energy change from adiabatic drift is often smaller than other source and loss processes, especially during quiet times. Energization from adiabatic drift dominates ring current growth only during portions of the main phase of storms. Furthermore, the net-adiabatic energization is often positive, because some particles are lost in the inner magnetosphere before they can adiabatically deenergize. It is shown that the inclusion of only this net-adiabatic drift effect in the total source rate or loss lifetime (depending on the sign of the net-adiabatic energization) best matches the observed source and loss values from empirical Dst predictor methods (that is, for consistency, these values should be compared between the calculation methods). While adiabatic deenergization dominates the loss timescales for all Ey,sw values, there is a characteristic decrease in the loss lifetime for higher Ey,sw, seen computationally and observationally. It is shown that these shorter loss lifetimes at higher Ey,sw are caused primarily by enhanced dayside flow out. The simulation results show that, on average, flow out is a larger energy loss term than charge exchange (the next biggest loss term for the ring current) for all Ey,sw values.

BACKGROUND DATA FILES

Abstract

Keywords
Magnetospheric Physics, Ring current, Magnetospheric Physics, Storms and substorms, Magnetospheric Physics, Numerical modeling, Magnetospheric Physics, Magnetosphere--inner
Journal
Journal of Geophysical Research
http://www.agu.org/journals/jb/
Publisher
American Geophysical Union
2000 Florida Avenue N.W.
Washington, D.C. 20009-1277
USA
1-202-462-6900
1-202-328-0566
service@agu.org
Click to clear formClick to return to previous pageClick to submit