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4th Swarm QWG Meeting 2 – 5 December 2014 GFZ Potsdam/D
• Data Selection• Model Parameterization• Results: Statistics, Lithospheric Field, Core Field• Perspective …
4th Swarm QWG Meeting 2 – 5 December 2014 GFZ Potsdam/D
• Vector and scalar data: selection criteria similar to CHAOS-4• nightside data (sun at least 10 below horizon)• |d RC/dt | < 2 nT/hr• vector data (in instrument frame) from non-polar regions (< 55 QD latitude)
if Kp < 2o
• scalar data from polar regions if Em < 0.8 mV/m
• “Gradient” (horizontal difference) data:• only scalar, no vector gradient• Inclusion of periods of higher geomagnetic activity (Kp < 3o, |d RC/dt | < 3
nT/hrand of dayside non-equatorial (> ±10 QD latitude) data
Data Selection
4th Swarm QWG Meeting 2 – 5 December 2014 GFZ Potsdam/D
Data Distribution
4th Swarm QWG Meeting 2 – 5 December 2014 GFZ Potsdam/D
Static (crustal) field up to degree n = 70 Linear time dependence (secular variation) for n = 1 – 13 Large-scale magnetospheric field (similar to CHAOS-4
parameterization) Co-estimation of instrument alignment parameters (Euler
angles) in bins of 10 days
Model Parameterization
4th Swarm QWG Meeting 2 – 5 December 2014 GFZ Potsdam/D
Model Residual Statistics
4th Swarm QWG Meeting 2 – 5 December 2014 GFZ Potsdam/D
Crustal Field
4th Swarm QWG Meeting 2 – 5 December 2014 GFZ Potsdam/D
Normalized coefficient difference
4th Swarm QWG Meeting 2 – 5 December 2014 GFZ Potsdam/D
Crustal Field Map
SIFM – MF7Backus-effect signaturein high degree (n > 60) terms
Br at surface, n = 16 - 65
4th Swarm QWG Meeting 2 – 5 December 2014 GFZ Potsdam/D
Secular Variation
4th Swarm QWG Meeting 2 – 5 December 2014 GFZ Potsdam/D
Secular Variation Map
Br at Core Mantle Boundary, n = 1 - 11
4th Swarm QWG Meeting 2 – 5 December 2014 GFZ Potsdam/D
Scalar residuals vs. latitude
4th Swarm QWG Meeting 2 – 5 December 2014 GFZ Potsdam/D
Conclusions
• Inclusion of gradient data improves crustal field and secular variation• Use of data during higher magnetic activity and from dayside (14% 46% of
all data)
• crustal field mainly improved by EW gradient data• secular variation mainly improved by NS gradient data
• Scalar difference SW-A – SW-C: • Mean: -120 pT• rms: 280 pT
4th Swarm QWG Meeting 2 – 5 December 2014 GFZ Potsdam/D
Inter-satellite calibration of SW-CHow to calibrate VFM(C) without ASM(C) ?Mapping of F : SW-A SW-C
• FASM(A)
• subtract Fmodel(A), add Fmodel(C) …
• … to obtain an estimate of F’ (C)• use this value to calibrate VFM(C)
all data: s = 0.55 nTnightside non polar: s = 0.28 nT
Comparison FASM (A C) – FASM (C)
daysidenightside
4th Swarm QWG Meeting 2 – 5 December 2014 GFZ Potsdam/D
SIFM without ASM(C)
Inter-satellite calibration of VFM(C) using ASM(A)
SIFM-type model from FVFM(C), without ASM(C)