EMAG3: A 3‐arc‐minute resolution global magnetic anomaly grid compiled from satellite, airborne and marine magnetic data

Abstract

NOAA's National Geophysical Data Center (NGDC) has extensive holdings of airborne and marine magnetic data. Such data have been collected for more than half a century, providing global coverage of the Earth. Due to the changing main field from the Earth's core, and due to differences in quality and coverage, combining these data to a consistent global magnetic anomaly grid is challenging. A key ingredient is the long wavelength magnetic field observed by the low-orbiting CHAMP satellite. To produce a homogeneous grid, the marine and aeromagnetic trackline data are first line-leveled and then merged with the existing grids of continental-scale compilations by Least Squares Collocation. In the final processing step the short-to-intermediate wavelengths of the near-surface grid are merged with a CHAMP satellite magnetic anomaly model. In analogy to NGDC's 2-arcminute resolution ETOPO2 grid, we call our initial 3-arcminute magnetic anomaly grid EMAG3. The grid will be updated regularly. It is available in digital form and as plug-ins for NASA World Wind and Google Earth.

What Drives the Continental Crust To Be Extremely Hot So Quickly?

“…Advected heat from magmatic intrusion must therefore be invoked in this case, owing to the almostidentical age of gabbronorite emplacement and UHT metamorphism. Based on the geophysical dataset of EGM08 and EMAG3 (Maus et al, 2008;Pavlis et al, 2012), the study area is characterized by positive free air gravity and high magmatic anomalies, indicating more mafic lithology. In fact, most of the rapid UHT terranes summarized by Kelsey and Hand (2015), such as Ongole Domain from Eastern Ghats Belt, India and Gruf Complex, northern Italy, also have similar geophysical characteristics, even though without extensive mafic intrusion explosure (cf.…”