Cluster Observations Around Magnetic Null
This plot shows the high-resolution (0.04 seconds) magnetic field data of four Cluster spacecraft and the calculated Poincaré index during 05:03:30-05:03:50 UT on 15 September 2001.
|The z component of magnetic field data of C1-C4|
|The Poincaré index is calculated from intercalibrated high resolution data|
A magnetic null is characterised by a Poincaré index equal to 1, such as around 05:03:36 UT. Outside this time period, the Poincaré index is found to be less than 10-6.