Magnetic Discrimination of Helicopter Data for Characterization of UXO Contaminated Sites

Low-level helicopter magnetometer data were collected over a site in Northern California that was contaminated with unexploded ordnance (UXO). Density estimates computed by selecting potential metallic anomalies from a derived total-gradient image identified a suspected bombing target but were distorted by large numbers of picks caused by geology. A dipole model was fit to each anomaly and used to estimate the apparent magnetic remanence. Restricting attention to items with low apparent remanence more clearly delineated the bombing target region and effectively eliminated the distortion of the density estimates caused by geology.