The IMF is a vector (B) that can be characterized by three independent components (BX, BY, BZ). In the Geocentric Solar Magnetospheric (GSM) Coordinate System, the X-axis points from Earth to the Sun. The Y-axis is defined to be perpendicular to the Earth's magnetic dipole so that the X-Z plane contains the Earth's dipole axis.
Once the data is plotted, calculations are performed to identify instances where the interplanetary magnetic field time series exhibits an opposite direction to Earth's magnetic field, which naturally points toward the geographic north pole.
These calculations provide statistical information to determine when an event might be considered a magnetic reconnection scenario. Additionally, specific thresholds are applied to further refine the data.
Based on the data we select those events in which the direction of the z-component of the interplanetary magnetic field is opposite to the direction of the earth's magnetic field and we use an additional threshold to restrict those events whose velocity, density and temperature exceed a minimum level (the average in the selected period).