Airborne geophysical survey: Pine, Minnesota and Wisconsin

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）由机载仪器沿飞行航线采集，同步记录磁场强度与位置信息。在早期航空磁测作业中，仅能通过绘制带等值线的模拟地图来呈现此类数据。本数据集为数字化等值线的呈现形式，可通过沿等值线追踪采样，或选取等值线与飞行航线的交点来获取对应磁场强度数值。所呈现的数据集字段包含纬度、经度与航磁图磁场强度值。