Figure 1
From: Ionospheric current contribution to the main impulse of a negative sudden impulse
![Figure 1](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2F1880-5981-66-92/MediaObjects/40623_2013_Article_131_Fig1_HTML.jpg)
Solar wind and IMF parameters on 14 May 2009 between 10:00 and 17:00 UT. Bx, By, and Bz are interplanetary magnetic field components; PSWmag and PSWdyn are magnetic and dynamic pressures of the solar wind, respectively; VSW and NSW are the velocity and density of the solar wind recorded by ACE satellite (all parameters are displayed without correction for travel time delay). Bottom plot shows SYM-H index where the MI of the negative impulse is shown between two vertical lines.