High-resolution magnetic field modeling: application to MAGSAT and طrsted data

Launched on 23rd February 1999, the Ørsted satellite opened the decade of geopotential field research. This is the first satellite to measure the three components of the Earth’s magnetic field since MAGSAT (1979–1980). Ørsted orbital parameters are very similar to those of MAGSAT, allowing a first-order comparison of the 1979 and 2000 magnetic fields. Using the available vector and scalar data over the first 14 months of the Ørsted mission and applying classical selection criteria (local time, external magnetic activity), we compute a 29-degree/order main-field model and a 13-degree/order secular-variation model for the period 1999–2000. The applied method and the accuracy of the derived model are discussed. We compare the resulting main-field model to a similar one derived from MAGSAT data. Results of this comparison are presented, such as (i) morphology and energy spectrum of the secular variation and (ii) morphology of the crustal magnetic field at MAGSAT and Ørsted epochs.