Accelerometers in low Earth orbits Anja Schlicht Technische

Accelerometers in low Earth orbits Anja Schlicht Technische Universität München

Disturbances on Accelerometers CHAMP, GRACE: heater, torquer, twangs GOCE: correlated noise Courtesy Jakob Flury

Observation: no magnetic interaction Courtesy Jakob Flury

Propagation of Electromagnetic Signals in the Ionosphere Handbook of Atmospheric Electrodynamics Vol. 2

Whistler Stanford VLF Group

Comparison of Whistler and very long Twangs

Very long twang

Occurrence of twangs and their oscillation length

Helicon mode in metalls ḻB ǁB Chiu and Quinn IL NUEVO CIMENTO 10 1972

Natural VLF in Ionosphere and Magnetosphere

What about these signatures?

Thermospheric mass density and auroral hiss ρCHAMP – ρMSIS 90 CHAMP ISIS-2 Occurance frequency of auroral hiss with magnetic local time Liu et al. 2005 Ondoh 1991

CARISMA (canadian array for Realtime investigations on magnetic activity) Courtesy Sinem Ince

Current (Voltage) Switching Effects 1. Long duration until signal is coupling into the accelerometer 2. Signal inversion with switchoff Courtesy Jakob Flury

Correlated Noise in GOCE

Oscillations Courtesy Jakob Flury

Interaction with ion-thruster in GOCE

Thank you very much!

Common Mode Signatures in Vyy Common mode Cross-track Vyy Scaling factor: -2. 75 (green) -3. 37 (red) -4. 00 (cyan)