The EM-Sled consists of the sensor housing, a red tube that contains the EM and GPS sensors, being mounted on a purpose-built, non-conductive sled. The unit is pulled by a person carrying a small battery pack and user interface that displays the real-time data that are also stored on the computer located inside the red tube. The operator can stop and start the system and break up line sections as required by project objectives. The sled and system tube weigh approximately 20 lbs. The GPS sensor has a 12-channel receiver and samples the sled location every second.
The electromagnetic sensor consists of a vertically oriented transmitter operating at 9kHz with dual receiver coils in the vertical (HCOP) and perpendicular (PRP) orientations. The transmitter-receiver coil separation is 1 m. The 3 most accurate electromagnetic data components, the HCOP in-phase and quadrature and the PRP quadrature, are used to estimate the ice thickness and its average conductivity through real-time 1D nonlinear inversion.
Ice thickness profile line extending from the thick calibration line (0 to 50 m) to the thin calibration area (430-475 m). A rafted and ridged ice area separated the two regions (samples 200 to 350). (from Prinsenberg and Holladay, 2009, Figure 7)
- Prinsenberg, S. J. and S. Holladay. 2009. "Ice Thickness Measurements with a Miniature Electromagnetic Sensor Sled"
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