Swarm IPF Level 1B Data dated 16. and 17. July 2005 as agreed at L2PS CDR

Analysis of Magnetic Data by DTU

Comparison of the 2 x 24 hours data dated 16. and 17. July 2005 with 2 hour data scenario starting 15. July 2005 at 23:45 and supposedly using the same scenario configuration shows a number of similarities and differences.

Plots of the field vectors in the VFM frame vs geomagnetic co-latitude seem quite consistent - and (somewhat) reasonable:

• VFM_y (green) - horizontal sideways - is small 
• VFM_x (blue) moving between plus and minus 40-50 uT, positive at the North pole, negative at the South. This is consistent with a downward component (although we would have expected this to be VFM_z).
• VFM_z (red) forming a flat ellipsoid with +/- ca. 30 uT at the equator consistent with a forward (wrt. flight) component (again we would have expected this to be the VFM_x axis)

Plots of the field vectors in the NEC frame vs geomagnetic co-latitude is shown next. The 2 hour simulation looks ok, but the 24 hour data looks quite chaotic - though with clear features similar to the 2 hour scenario.

Finally plots of the rotations as 1-2-3 Euler angles from the Common Reference Frame (CRF - which should be defined to be equal to the S/C frame, but maybe not in the 24 hour data?) to the NEC frame is shown.
The top plot shows the 2 hour "reference" scenario, which shows an expected semi-steady behaviour: no rotation going North, and a 180 degree rotation about z when going South.
The middle plot below shows the first 2 hours from the 24 hour data - here all three rotation angles are constantly varying.
The bottm plot shows all 24 hours, which seem quite chaotic.

A plot of the scalar field together with the CHAOS-3 model prediction is given below and shows significant differences.