introducing pomme potsdam magnetic model of the earth star camera calibration ring current field...
TRANSCRIPT
Introducing POMME Potsdam Magnetic Model of the Earth
• Star camera calibration• Ring current field• Static and annually varying external fields• Internal field
Stefan [email protected]
Stefan Maus, George Balasis,
Hermann Lühr and Martin Rother, GFZ
Mioara Mandea, IPGP
POMME main field model
Internal field:
• Gauss coefficients gnm
to degree 15 tgn
m to degree 15
ttgnm to degree 10
External field:• Dst dependent external
dipole aligned with internal field dipole
• Gauss coefficients knm to
degree 2 in Geocentric Solar Magnetic (GSM) coordinatesStar camera angle:
• corrections for 6 time intervals
Oersted data before/after median filter
Residuals against initial field model
Calibration for the angle between the star sensor and the vector magnetometer
Fluxgate vector magnetometer
Starsensor
Z residuals against Pomme 1.4
Dst dependence of earlier field models
Dst dependence of Pomme
Dst versus induced RC field of Pomme
Magneto-sphere
A constant external field in GSM: Annual variation seen by an Earth fixed observer at
0 degree longitude, 30 degree latitude
A constant external field in GSM: Comparison with CO2’s external field
(observer at 0 degree longitude, 30 degree latitude)
Main field model power spectrum
Model with 3rd time derivative
Conclusions
Stefan [email protected]
Data errors: Important to take instrument errors, star camera mis-alignment and F-Region currents into account
New features in POMME: • Includes co-estimated star camera angles for CHAMP• Imposed realistic Dst dependence of RC field• Describes magnetospheric fields in GSM coordinates• Includes secular acceleration
See: www.gfz-potsdam.de/pb2/pb23/SatMag/model.html
Examples of Instrument Problems
Examples of genuine magnetic disturbances
Diamagnetic effect at 20:00 local time
Night sideF region currents
E - Region
B
Regions of enhanced plasma density
E - Region
B
Regions of enhanced plasma density
E - Region
B
Regions of enhanced plasma density
CHAMP electron density, 23-23 Oct 2001, 20 LT
Diamagnetic effect at 20:00 local time
Satellites POGO (1967-1971)
MAGSAT (1979-1980)– 350 – 650 km altitude– mission duration: 6 months
Oersted (since 1999)SAC-C (since 2001)
– 600 – 800 km altitude
CHAMP (since 2000) – 450 km altitude, decending– 5 year mission