GREENMAG - Magnetic anomaly map of Greenland

Greenland Magnetic Compilation (GREENMAG) ==================================== The development of this new magnetic compilation from Greenland (GREENMAG) was initiated by the working group of Satellite- and Aerogeophysics at the Christian-Albrechts-University (CAU) in Kiel, Germany, and GEUS as part of the ESA project GOCE+Greenland in 2021. The here presented magnetic anomaly map covers whole Greenland including the Inland Ice and the adjacent shelf regions. It is built out of all accessible modern regional aeromagnetic surveys from Greenland but also uses older datasets without GPS positioning in areas where modern data are lacking. Magnetic data are currently taken from the surveys of the projects AEROMAG, AEM, GICAS, EASTMAR, ICEBRIDGE, GAP91/92, AWI93-96, LOMGRAV, NOO-73, several projects from the German Federal Institute for Geosciences and Natural Resource (BGR), Geological Survey of Canada (GSC) and Alfred Wegener Institute (AWI) and from offshore datasets acquired by the TGS-NOPEC TGS GEOPHYSICAL COMPANY. Since long wavelength components in aeromagnetic data are often considered as unreliable, they are replaced by the ones from the LCS-1 satellite model (Gaussian coefficients with degrees n = 13 – 133). The magnetic anomaly map is generated by a methodology that combines equivalent source modelling and a spherical harmonic expansion. The datapoints at their actual measuring locations are used as data input and magnetic dipoles are employed as equivalent sources that are arranged in three uniform grids with different source spacing and depths (coarsest spacing: 10 x 10 km; finest spacing: 0.7 x 0.7 km). The presented magnetic anomaly map is simulated from the dipole responses at a constant height of 2000 m asl and with a grid spacing of 400 x 400 m. Regularizations in the inversion for the different equivalent source grids are chosen such that the resulting resolution is flexible and adapted to the largely varying magnetic data coverage in Greenland. Data Download ============ Downloadable data include (1) the GREENMAG magnetic anomaly map as ArcView Binary Raster Grids (files *.flt, *.hdr) and in a column based ASCII-table (files *.XYZ) and (2) a table with the locations of used data points. The magnetic anomaly maps are provided as two versions. One is simulated from all three equivalent source grids, but the other is simulated only from the coarse and medium equivalent source grids.