* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Ørsted - The first Danish Satellite
Maxwell's equations wikipedia , lookup
Edward Sabine wikipedia , lookup
Superconducting magnet wikipedia , lookup
Electromagnetism wikipedia , lookup
Magnetic stripe card wikipedia , lookup
Lorentz force wikipedia , lookup
Neutron magnetic moment wikipedia , lookup
Giant magnetoresistance wikipedia , lookup
Mathematical descriptions of the electromagnetic field wikipedia , lookup
Magnetometer wikipedia , lookup
Magnetic monopole wikipedia , lookup
Magnetotactic bacteria wikipedia , lookup
Electromagnetic field wikipedia , lookup
Electromagnet wikipedia , lookup
Force between magnets wikipedia , lookup
Earth's magnetic field wikipedia , lookup
Multiferroics wikipedia , lookup
Magnetohydrodynamics wikipedia , lookup
Magnetochemistry wikipedia , lookup
Magnetoreception wikipedia , lookup
Ferromagnetism wikipedia , lookup
Geomagnetic reversal wikipedia , lookup
Magnetotellurics wikipedia , lookup
Magnetic fields induced in the solid Earth and oceans Alexei Kuvshinov & Nils Olsen Danish National Space Center, Copenhagen, Denmark • Predicting magnetic signals induced in 3-D conductivity Earth by various sources - Sq and EEJ - Geomagnetic storms - Ocean tides and global circulation • Possible utilization of 3-D predictions in geomagnetic field modeling • Conclusions Forward problem formulation and 3-D Earth’s model ext Calculate EM field induced by a given j (t , r , , ) in Earth’s model of a given (r , , ) Governing (Maxwell’s) equations: 1 o B (r , , )E jext (t , r , , ) B E . t Existing numerical solutions: Fainberg et al., 1990; Tarits, 1994; Everett & Schultz, 1996; Martinec, 1999; Uyeshima & Schultz, 2000; Tyler et al., 1999, 2002; Koyama et al., 2002; Kuvshinov et al., 2002; 2005 (VIE approach) Yoshimura & Oshiman, 2002; Hamano, 2002; Weidelt, 2004; Velimsky et al., 2005 Basic 3-D conductivity model: S ( , ) b (r ) Conductance Varies from 0.1 S up to 35000 S b (r ) (r,, ) 3D magnetic fields due to Sq current system Source: Sq of 21 March 2000 (from CM4; Sabaka et al.,2004) Sea level Altitude of 400 km 3D Br (inducing + induced parts) Ocean effect (up to 12 nT) Ocean effect (up to 6 nT) Magnetic fields due to equatorial electrojet (EEJ) Source: EEJ of 21 March 2000 (from CM4) Sea level Ocean effect (up to 4 nT) Altitude of 400 km Ocean effect (up to 1 nT) Magnetic fields due to geomagnetic storms Source: storm of 5-6 November, 2001 Sea level Ocean effect (up to 80 nT) Altitude of 400 km Ocean effect (up to 30 nT) Magnetic fields due to geomagnetic storms (contd.) Z at HER for selected storms Olsen & Kuvshinov, 2004 Z at coastal obsrvatories for storm 13 July 2000 Magnetic fields due to ocean tides Movement of sea water through the main field: Source: Jext S U B M2 tidal model by Egbert & Erofeeva (2000) Predictions from Kuvshinov & Olsen (2005) Magnetic fields due to ocean tides (contd) Magnetic effect of oceanic M2 tide as seen by CHAMP Observed Predicted Tyler, Maus & Luhr, 2003 Magnetic fields due to ocean tides (contd.) Tidal correction for MF4 model Tides Period, days M2 0.5176 S2 0.5 N2 0.5274 K2 0.4986 K1 0.9973 O1 1.0758 P1 1.0027 Q1 1.1195 The spectrum of the magnetic residuals over the Indian Ocean before (black) and after (red) subtracting our predictions from 8 major tidal constituents (Maus et al., 2005). Magnetic field due to ocean circulation Ocean circulation velocities (ECCO model) Source Jext S U B 0 • The magnetic signals are largely influenced by the Antarctic Circumpolar Current (ACC). Br at 430 km • The largest signature is in Br with peak-to-peak values of order 3 nT. Manoj et al., 2005 Possible utilization of 3-D predictions in geomagnetic field modeling • Signals due to ocean flows – subtracting the 3-D predictions from the data Bexp ,refined Bexp Bocean flows • Signals of magnetospheric origin – decomposition of Dst = Est + Ist (Maus & Weidelt, 2004) using 3-D conductivity model • Signals of ionospheric origin – replacement of 1-D responses by 3-D ones Conclusions • 3-D induction effects contribute much to near-Earth magnetic field • These effects can be predicted with required accuracy and detail by using modern numerical solutions • 3-D predictions can be readily incorporated into modern geomagnetic field modeling schemes