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

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

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

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

4 th Swarm DQW – Magnetic Session 23 Dec 2014Potsdam (D) Swarm A Numbers Static bias: b = ( ) Sensitivities:  Static: s 0 = 1 + ( ) ×  Temporal: s t = × /year  Temperature: s Tsensor = ( ) × /°C

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