A programmable borehole measurement system was deployed in hot water drilled ice holes during the ‘Bed Access and Monitoring of Ice Sheet History’ (BEAMISH) project to drill to the bed of the Rutford Ice Stream in West Antarctica. This system operates autonomously (no live data) after deployment, and records borehole diameter (non-contact measurement), water column pressure, heading and inclination. Three cameras, two sideways looking and one vertical, are also included for visual inspection of hole integrity and sediments. The system is small, lightweight (~35.5 kg) and low power using only 6 ‘D’ cell sized lithium batteries, making it ideal for transport and use in remote field sites. The system is 2.81 m long and 165 mm in diameter, and can be deployed attached to the drill hose for measurements during drilling or on its own deployment line afterwards. The full system is discussed in detail, highlighting design strengths and weaknesses. Data from the BEAMISH project are also presented in the form of camera images showing hole integrity, and sensor data used to calculate borehole diameter through the full length of the hole. These data are used to show confidence in hole verticality and subsurface cavity development and connection.

Two methods for modeling the electromagnetic fields near a lightning channel are considered. These methods can be used in evaluating the effect of a lightning electromagnetic pulse (LEMP) on a distribution line. The first method for evaluating LEMP fields in the time domain uses a Heidler function approximation for the channel base current in the classic Finite Antenna method. This approximation has an analytical integral solution which simplifies the field calculations. The second method is a combination of standard FDTD theory and the mathematics of the Finite Antenna method. The proposed Single Cell or Hybrid FDTD method is derived for spherical co-ordinates and tested against the Finite Antenna method. The results show that under simple modeling criteria both methods are valid for LEMP calculations near a lightning channel. The Single Cell FDTD method only evaluates a single FDTD cell, rather than an entire plane of cells described by the standard FDTD method. This greatly reduces the computational intensity, and makes the Single Cell FDTD method a valuable tool.