National Geophysical Data Center candidate for the World Digital Magnetic Anomaly Map

Marine and airborne magnetic anomaly data have been collected for more than half a century, providing global coverage of the Earth. Furthermore, the German CHAMP satellite is providing increasingly accurate information on large‐scale magnetic anomalies. The World Digital Magnetic Anomaly Map project is an international effort to integrate all available near‐surface and satellite magnetic anomaly data into a global map database. Teams of researchers were invited to produce candidate maps using a common pool of data sets. Here we present the National Geophysical Data Center (NGDC) candidate. To produce a homogeneous map, the near‐surface data were first line‐leveled and then merged by Least Squares Collocation. Long wavelengths were found to agree surprisingly well with independent satellite information. This validates our final processing step of merging the short‐wavelength part of the near‐surface data with long‐wavelength satellite magnetic anomalies.