International audienceThe eleventh generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2009 by the International Association of Geomagnetism and Aeronomy Working Group V-MOD. It updates the previous IGRF generation with a definitive main field model for epoch 2005.0, a main field model for epoch 2010.0, and a linear predictive secular variation model for 2010.0–2015.0. In this note the equations defining the IGRF model are provided along with the spherical harmonic coefficients for the eleventh generation. Maps of the magnetic declination, inclination and total intensity for epoch 2010.0 and their predicted rates of change for 2010.0–2015.0 are presented. The recent evolution of the South Atlantic Anomaly and magnetic pole positions are also examined

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Based on magnetic field data from the Swarm satellite constellation advanced estimates of field-aligned and radial currents at middle and low latitudes can be derived. Detailed results have been obtained for low-latitude (14°-35°magnetic latitude) interhemispheric field-aligned currents related to the solar quiet (Sq) current system. The continuous data set of five years allows resolving the dependences on local time, season, and longitude. We confirm the known current flow from the southern to the northern hemisphere around June solstice. Unexpected results are obtained for the months following December. Stratospheric sudden warming events are suggested as a reason for that. These phenomena are known to amplify lunar tides and atmospheric planetary waves. Furthermore, we investigated the mean characteristic of the meridional current systems connected to the wind-driven F region dynamo above the magnetic equator. Typical features of radially downward currents around noon and upward currents in the evening sector could be confirmed. From a detailed analysis of the connected field-aligned current distribution we deduced that the mean altitude of the dynamo region is higher in the evening than around noon. And it appears also at greater heights in the western hemisphere than in the eastern. Special current configurations are encountered in the longitude range containing the South Atlantic Anomaly. Here summer-like conditions are prevailing through all seasons. This infers that the ionospheric conductivity is significantly enhanced in this region of weak magnetic field strength.

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[1] The CHAMP satellite continues to provide highly accurate magnetic field measurements from decreasing orbital altitudes (<350 km) at solar minimum conditions. Using the latest 4 years (2004)(2005)(2006)(2007) of readings from the CHAMP fluxgate magnetometer, including an improved scalar data product, we have estimated the lithospheric magnetic field to spherical harmonic degree 120, corresponding to 333 km wavelength resolution. The data were found to be sensitive to crustal field variations up to degree 150 (down to 266 km wavelength), but a clean separation of the lithospheric signal from ionospheric and magnetospheric noise sources was achieved only to degree 120. This new MF6 model is the first satellitebased magnetic model to resolve the direction of oceanic magnetic lineations, revealing the age structure of oceanic crust.