Geomagnetism

Real-time data from the ACE satellite:

• The interplanetary electric field (also known as the solar wind electric field) is calculated from the interplanetary magnetic field and solar wind velocity.  We use the data from the Advanced Composition Explorer (ACE) satellite. ACE orbits the L1 libration point which is Help 1.5 million kilometers from the Earth, facing the sun. Due to large distance of ACE   from the earth in the upstream direction,  the data provides around 1 hour of advance information about the solar wind condition. The real-time interplanetary data are obtained from the NOAA’ s Space Weather Prediction Center . The data are fetched every 15 minutes and processed for propagation delay and errors.


• The model requires the IEF data to be propagated from the satellite position to the bow shock nose of the Earth’s magnetosphere. For the real-time calculator,  we assume that the solar wind travels at a constant speed along the Sun-Earth line to the magnetosphere (t_delay = delta X / V), where delta X is the distance between ACE satellite and the magnetosphere’s bow shock nose along the Sun-Earth line, and V is the solar wind velocity.


• The real-time calculator can also be used to calculate the EEF for any dates from 1995 to present. For dates older than two months from the present, we use the interplanetary data from the OMNI web site. The data is derived from ACE, Wind, IMP 8 and Geotail satellites and is  time shifted to the Earth's bow shock nose using a combination of minimum variance and cross product phase front normal determination techniques.


• The solar flux data for the climatologcal model is  derived from the SWPC data service.  The model uses the the 81-day moving average of F10.7 cm solar flux.