Magnetopause Model

How to use this tool:
Button                    Function
Next                      next day 
Prev                      previous day
Review                    review one days solar wind data (date displayed in text fields)
ReviewAll                 review last 5 days data (all available)
Scenario                  enter solar wind parameters in text field
                          and compute magnetopause location based on
                          input. Also, if the longitude of geosynchronous satellite
                          is entered, this will be added to the display.

This tool displays the estimated location of the magnetopause (the balancing point between the Sun's solar wind pressure and the Earth's magnetic field pressure). This balancing point primarily depends on the speed and density of the solar wind. The solar wind data used for this model originates from the US ACE (Advance Composition Explorer) spacecraft orbiting the L1 point (a point between the Sun and Earth where gravitational forces balance).

The graphical presentation is in the equatorial plane as viewed from above the Earth's north pole. Geosynchronous orbit is shown at a distance of 6.6 Earth radii (Re) from the centre of the planet. The location of up to 6 geosynchronous satellites may be indicated by small circles of different colours. The colours index into the legend in the lower right side of the window, where the satellite's name and longitudinal position is given.

References:
     1  Shue JH et al, "A new functional form to study the solar
			wind control of the magnetopause size and shape", JGR, v102, pp9497-9511, May 1997.
     2  Shue JH et al, "Magnetopause location under extreme solar wind 
			condition", JGR, v103, pp17691-17700, August 1998.

The ACE solar wind detector may saturate during strong proton events. Under such conditions ACE solar wind speed data appears to abruptly decrease to unrealistic values (ie <300km/sec), and density data appears to increase to unrealistic values, giving an incorrect estimate of the magnetopause location, particularly if a strong coronal mass ejection (with a fast solar wind speed) interacts with the Earth's magnetic field whilst the proton event is in progress. To avoid this situation, software at IPS will now switch to the SOHO MTOF solar wind proton monitor when solar wind speed drops below 300km/sec, as the SOHO MTOF solar wind proton monitor appears to be a more robust solar wind instrument during strong proton events. The ACE data is used at IPS as its data set is larger (ie a greater number of solar wind parameters, particularly the interplanetary magnetic field) than the MTOF instrument. The software switch to the SOHO data stream has been simulated at IPS, but has not yet been proven during a strong solar proton event.