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www.ann-geophys.net/26/2887/2008/
© European Geosciences Union 2008
Derivation of inner magnetospheric electric field (UNH-IMEF) model using Cluster data set
1Space Science Center, University of New Hampshire, Durham, NH 03824, USA
2Los Alamos National Laboratory, Los Alamos, NM 87545, USA
3Swedish Institute of Space Physics, 751-21 Uppsala, Sweden
4Royal Institute of Technology, 100-44 Stockholm, Sweden
Abstract. We derive an inner magnetospheric electric field (UNH-IMEF) model at L=2–10 using primarily Cluster electric field data for more than 5 years between February 2001 and October 2006. This electric field data set is divided into several ranges of the interplanetary electric field (IEF) values measured by ACE. As ring current simulations which require electric field as an input parameter are often performed at L=2–6.6, we have included statistical results from ground radars and low altitude satellites inside the perigee of Cluster in our data set (L~4). Electric potential patterns are derived from the average electric fields by solving an inverse problem. The electric potential pattern for small IEF values is probably affected by the ionospheric dynamo. The magnitudes of the electric field increase around the evening local time as IEF increases, presumably due to the sub-auroral polarization stream (SAPS). Another region with enhanced electric fields during large IEF periods is located around 9 MLT at L>8, which is possibly related to solar wind-magnetosphere coupling. Our potential patterns are consistent with those derived from self-consistent simulations. As the potential patterns can be interpolated/extrapolated to any discrete IEF value within measured ranges, we thus derive an empirical electric potential model. The performance of the model is evaluated by comparing the electric field derived from the model with original one measured by Cluster and mapped to the equator. The model is open to the public through our website.
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Citation: Matsui, H., Puhl-Quinn, P. A., Jordanova, V. K., Khotyaintsev, Y., Lindqvist, P.-A., and Torbert, R. B.: Derivation of inner magnetospheric electric field (UNH-IMEF) model using Cluster data set, Ann. Geophys., 26, 2887-2898, 2008. Bibtex EndNote Reference Manager
