Testing geomagnetic reference field models for 1990-2000 with data from the trelew geomagnetic observatory, Argentina

Abstract

Every five years a new International Geomagnetic Reference Field (IGRF) model is released and the secular variation for the previous period is updated, producing the definitive DGRF model. Once a DGRF is released, the previously calculated magnetic anomalies are updated. We show the importance of this correction for the 1995-2000 period, in which the DGRF-IGRF difference is anomalously large. We document the validity of the correction by using data from the permanent geomagnetic Observatory of Trelew, Argentina.