World Digital Magnetic Anomaly Map
Schemes of Map Compilation
Definition
The WDMAM (2007 and 2008 versions) will represent the total field magnetic anomalies of the Earth's lithosphere at the grid interval of about 5 km (specifically, 3 minutes of latitude/longitude) and altitude of 5 km above the geoid and upto spherical harmonic degree 15 (about 2600 km wavelength). The contributors may freely choose the methods of merging short as well as long wavelength parts of the field, provided that they are transparent, scientific, and reproducible and are proven robust during the review process.
Issues to take care
- Transient variation
- Secular variation
- Baselines
- Epoch
- Elevation
- Normal field
- Frequency band
- Sampling
- Noise
- Computing techniques
