IMAGE/BEAR

General overview of the BEAR project is given on the official BEAR home page.

FMI tasks

Specific tasks defined in the INTAS project:

1. Compilation of the time series database

This concerned mainly providing IMAGE magnetometer data, and recordings from a few MT stations.

2. Search for plane wave events at 1000-20000 s

This problem can be approached by searching for events which are not due to plane waves. The remaining time sequences may be plane wave events. Quick-look results are presented as plots of electrojet locations in June - July 1998.

The currents can be determined more quantitatively by using a 2-D magnetometer array, and BEAR provides an excellent data set for that purpose. The final aim is to provide a full description of the (equivalent) ionospheric current system.

3. Splitting of tipper arrows into simultaneous magnetic components

This is based an earlier magnetometer arrays operated in Finland.

4. Forward complex image methods and non-uniform source fields

Assuming a layered conductivity structure of the earth, the electric and magnetic field at the earth's surface can be computed by an efficient image approximation. The ionospheric current system is given as an input, and it can have any horizontal distribution (with associated vertical field-aligned currents) and time dependence.

Other possibilities

Task 2 provides useful input to ionospheric-magnetospheric studies too. For example, as a 2-D network, BEAR gives a good opportunity to study east-west moving ionospheric structures, better than with IMAGE only.

Results of task 4 are directly applicable when induced currents in power systems and pipelines are estimated.


BEAR international home page
IMAGE home page
Updated: 13.3.2009