1. 4 th Swarm DQW – Magnetic Session 23 Dec 2014Potsdam (D) ELM – “EXTENDED” LESUR MODEL OF DISTURBANCE CHARACTERISATION AND VFM CALIBRATION Lars Tøffner-Clausen, Nils Olsen, Peter Brauer DTU Space special thanks to Vincent Lesur

2. 4 th Swarm DQW – Magnetic Session 23 Dec 2014Potsdam (D) Model Parameterisation Vector field disturbance at VFM sensor  “Vincent Lesur model”: Solar angle dependent, spherical harmonic model to d/o 30, including static part  No time varying bias VFM instrument sensitivity  Static part, one value for each axis  Time-dependent part, linear, one common value for all three axes  Sensor temperature dependent part, linear, one value for each axis (small correction to pre-flight values)  No non-orthogonality corrections

3. 4 th Swarm DQW – Magnetic Session 23 Dec 2014Potsdam (D) Swarm C Results

4. 4 th Swarm DQW – Magnetic Session 23 Dec 2014Potsdam (D) Swarm A Results

5. 4 th Swarm DQW – Magnetic Session 23 Dec 2014Potsdam (D) Swarm A Numbers Static bias: b = (0.7033 -1.9407 0.0323) Sensitivities:  Static: s 0 = 1 + (99.08 64.19 -27.89) × 10 -6  Temporal: s t = -79.4 × 10 -6 /year  Temperature: s Tsensor = (0.9864 0.6030 0.6980) × 10 -6 /°C

6. 4 th Swarm DQW – Magnetic Session 23 Dec 2014Potsdam (D) What next? Add fit of non-orthogonalities Further analysis of temporal evolution of VFM sensitivity Assessment of required input data span to obtain accurate vector disturbance model solution