Lab 3: Tracing field lines and magnetic field models of Earth

Author: R.S. Weigel
Date: 06/02/2005
Note: Prepared for 2005 NCAR Summer school.

Modified-By: R.S. Weigel
Date: 11/02/2005
Note: Added questions, changed grid to rectangular, made grid unpickable.

Keywords and Acronyms:

Tsyganenko model: "The Tsyganenko model is a semi-empirical best-fit representation for the magnetic field, based on a large number of satellite observations (IMP, HEOS, ISEE, POLAR, Geotail, etc). The model includes the contributions from external magnetospheric sources: ring current, magnetotail current system, magnetopause currents and large-scale system of field-aligned currents" []

IGRF Field model (International Geomagnetic Reference Field): "... a standard mathematical description of the Earth's main magnetic field and used widely in studies of the Earth's deep interior, its crust and its ionosphere and magnetosphere. The coefficients for this degree and order 13 main field model were finalized by a task force of IAGA in December 2004. The IGRF is the product of a collaborative effort between magnetic field modelers and the institutes involved in collecting and disseminating magnetic field data from satellites and from observatories and surveys around the world." []

Online References:

Physics Background:
The following link was excerpted from the AFWA Space Weather Forecasting training material.

Earth's Magnetic Field: for an overview over its structure click here


Loading the network

To start Lab03 with CISM_DX extensions, click here ; this will cause a Visual Program Editor window to open.

Main Control Panel

Once the new network is loaded we need to open the Main Control Panel. In OpenDX, control panels are used to allow for user interaction with a network. You can design a network so that the user does not need to interact with the VPE. Instead, the user modifies parameters in a control panel and manipulates an image with the mouse.

In the top menu bar, select Windows, Open Control Panel by Name, and then Main Control Panel. The Main Control Panel contains a list of magnetic field models.

Empirical Models of Earth's Magnetic Field

Now execute Lab03 via CTRL+E. This network allows you to set the starting location for a set of magnetic field lines for various magnetic field models. When the image window is in focus (active), you can bring up the View Control Panel by typing CTRL-V. Alternatively, select Options, View Control from the image menu bar. Next, change the interaction mode by changing the Mode to Pick. Now mouse clicks will be interpreted as picks. If you accidently modified the image from what it was originally, use CTRL-Z to step back to a previous view.

Use the mouse to select three points on the green plane as origins for field lines and then execute the network. It's important to point out here that the Pick module is designed to set the points on the green plane that you can see in the image Window.

Test your knowledge:

You have completed Lab03; close this lab now by selecting File, Quit (CTRL+Q). Answer the prompt (Do you want to save the program?) with No, and then confirm to quit DX with Yes. Move on to the next lab.