Airborne geophysical survey: Arnold Pond Area, Maine

Aeromagnetic data were collected along flight lines by instruments in an
aircraft that recorded magnetic-field values and locations. In the earlier
days of surveying, the only way to represent this data was to generate an
analog map with contour lines. This dataset is a representation of the
digitized contour lines either by following the lines or by choosing the
intersection of the contour and flight-line to create a value of the magnetic
field. The values presented are latitude, longitude, and map magnetic-field
values.

航空磁力数据（aeromagnetic data）由搭载于航空器的测量仪器沿飞行航线采集，同步记录磁场强度与位置信息。在航空磁测的早期阶段，此类数据唯一的可视化方式为生成带有等值线的模拟地图。本数据集通过两种方式对数字化等值线进行还原：一是沿等值线轨迹进行采样，二是选取等值线与飞行航线的交点以获取对应磁场强度数值。本次公开的数据包含纬度、经度与航磁场强数值三类内容。