Abstract.Magnetic measurements taken by the Orsted satellite during geomagnetic quiet conditions around January 1, 2000 have been used to derive a spherical harmonic model of the Earth's magnetic field for epoch 2000.0. The maximum degree and order of the model is 19 for internal, and 2 for external, source fields; however, coefficients above degree 14 may not be robust. Such a detailed model exists for only one previous epoch, 1980. Achieved rms misfit is < 2 nT for the scalar intensity and < 3 nT for one of the vector components perpendicular to the magnetic field. For scientific purposes related to the Orsted mission, this model supercedes IGRF 2000.

Power grids and pipeline networks at all latitudes are known to be at risk from the natural hazard of geomagnetically induced currents. At a recent workshop in South Africa, UK and South African scientists and engineers discussed the current understanding of this hazard, as it affects major power systems in Europe and Africa. They also summarised, to better inform the public and industry, what can be said with some certainty about the hazard and what research is yet required to develop useful tools for geomagnetic hazard mitigation.

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Within the Inkaba yeAfrica project, the number of geomagnetic repeat stations surveyed in southern Africa has been increased recently from eight to almost 40, through cooperation between Hermanus Magnetic Observatory (HMO), South Africa and GeoForschungsZentrum Potsdam (GFZ), Germany. Taking advantage of the extensive network of well-marked repeat stations formerly established by HMO in South Africa, Namibia and Botswana, and experience gained in using on-site variometers in former repeat station surveys carried out by GFZ, we could significantly improve the spatial data coverage of the area and also the quality of the results. Here we report on the survey and data processing methods, and discuss the accuracy of results, particularly with respect to the ability of the data to reflect the undisturbed internal magnetic field. Moreover, we briefly discuss how differences in the variometer recordings can reflect possible lateral changes in lithospheric conductivity.

First ICRF experiments on ASDEX have been performed at 67 M z , corresponding to ZECH-heating of a hydrogen plasma at Bo = ?.2T. Despite divertor operation ICRH is accompanied by a significant increase of impurity production which can drastically be reduced by means of wall carbonisation. RF power up t o 2.3 MW is routinely coupled to the plasma for pulse lengths of up to 1 sec. The rf heating is found to depend strongly on plasma preheating. In conjination with neutral beam injection the ICRF heating efficiency is even higher than the one of SI. Confinement degrades with ICRH to values in between XI-L-type and OH confinement.

Rapid secular variation pulses in the Earth's geomagnetic field have been identified during the last decade. In particular, the 2014 jerk is the latest in a series of localised rapid secular variation events observed at the Earth's surface which are thought to be the result of rapid oscillations at the core surface approximately at a depth of 3000 km. In Southern Africa, the 2014 jerk has been analysed using data from four observatories located at Hermanus, Hartebeesthoek, Keetmanshoop and Tsumeb and found that this event occurred with varying strengths in the different components at a particular observatory, while different observatories in the region showed strong individual characteristics. The changes in the secular variation patterns at individual magnetic observatories in this study took place in an area characterised by rapid changes in the geomagnetic field with time. Of particular interest is that global field models like CHAOS-6 and POMME 10 derived from various combinations of ground and satellite data do not always indicate similar short-period patterns in X, Y and Z as revealed by observatory measurements. This has been confirmed by comparing the secular variation pattern at the Kourou magnetic observatory located in French Guiana, a station close to the current centre of the South Atlantic Anomaly.

The geomagnetic field at any given epoch is a function of space coordinates, varying differently at each location with time. It has been known that secular change is a comparatively local phenomenon and that it does not proceed in a regular way all over the Earth, giving rise to regions where the field changes more rapidly than elsewhere, like for instance southern Africa. The Hermanus Magnetic Observatory routinely executes geomagnetic repeat surveys, which includes South Africa, Namibia, Zimbabwe and Botswana. Spherical cap modelling of field survey and observatory secular variation data at 5 year intervals between 1975 and 2000 shows that a geomagnetic jerk occurred between 1980 and 1985 over southern Africa. The secular variation models are based on 70 repeat station data central differences as well as the 3 magnetic observatories at Hermanus, Hartebeesthoek and Tsumeb (Namibia) and include terms up to spatial degree 3 and temporal degree 2. Although each model allows for 48 coefficients, only 42 were found to be statistically significant.

Geomagnetic field data from four observatories and annual field surveys between 2005 and 2015 provide a detailed description of Earth's magnetic field changes over South Africa, Namibia and Botswana on time scales of less than 1 year. The southern African area is characterized by rapid changes in the secular variation pattern and lies in close proximity to the South Atlantic Anomaly (SAA) where the geomagnetic field intensity is almost 30 % weaker than in other regions at similar latitudes around the globe. Several geomagnetic secular acceleration (SA) pulses (geomagnetic jerks) around 2007, 2010 and 2012 could be identified over the last decade in southern Africa. We present a new regional field model for declination and horizontal and vertical intensity over southern Africa (Southern African REGional (SAREG)) which is based on field survey and observatory data and covering the time interval from 2005 to 2014, i.e. including the period between 2010 and 2013 when no low Earth-orbiting vector field satellite data are available. A comparative evaluation between SAREG and global field models like CHAOS-5, the CHAMP, Orsted and SAC-C model of the Earth's magnetic field and International Geomagnetic Reference Field (IGRF-12) reveals that a simple regional field model based on a relatively dense ground network is able to provide a realistic representation of the geomagnetic field in this area. We particularly note that a global field model like CHAOS-5 does not always indicate similar short-period patterns in the field components as revealed by observatory data, while representing the general secular variation reasonably well during the time interval without near-Earth satellite vector field data. This investigation further shows the inhomogeneous occurrence and distribution of secular variation impulses in the different geomagnetic field components and at different locations in southern African.