McKnight, J.D. 1996 An updated regional geomagnetic field model for New Zealand . Lower Hutt: Institute of Geological & Nuclear Sciences Institute of Geological & Nuclear Sciences science report 96/04 16 p.
Abstract: An updated model of the regional geomagnetic field for New Zealand is presented. It takes advantage of a data set that has expanded considerably since the last published update. This expansion permits adjustments to the procedure by which coefficients for the model are determined and results in an improved fit by the model in the central part of the region at the expense of that at remote sites. A comparison between the New Zealand regional field model and IGRF 1995 indicates that the IGRF has the better spatial fit overall for the New Zealand region. With regard to secular variation the regional field model has a better fit to longer-term trends (i.e. those with a decade timescale) in the horizontal components than does the IGRF, while the latter is superior for the vertical component. The result for the vertical component may be due to the test being inappropriate. A feature of the New Zealand regional field model is its accommodation of longer-term trends in the geomagnetic field and its consequent stability under extrapolation. The spatial fit of the regional model would be improved by using the full Project MAGNET data set when it becomes available and upgrading the model's functional form. (auth)