A comparative analysis and evaluation of the DGRF-85 and IGRF-90 candidate models

Abstract

Candidate models for the Definitive Geomagnetic Reference Field (DGRF) main field model at the 1985.0 epoch, as well as candidate models for the International Geomagnetic Reference Field (IGRF) main field model at the 1990.0 epoch along with the corresponding secular variation models at the 1992.5 epoch were evaluated against each other, and against data observations from both Project Magnet aeromagnetic data and recently obtained Polar Orbiting Geomagnetic Survey (POGS) satellite data. Models for the 1985.0 epoch show some regional differences in model by model comparisons but, in general, are quite similar. All models agree well with the observed Project MAGNET data. Models for the 1990.0 epoch showed greater differences that were still regional rather than global in nature. The same was true for the corresponding 1992.5 secular variation models. -from Authors