Methodology:

The datasets are ice deformation time series recorded by accelerometers mounted on strings installed into three boreholes drilled into Khumbu Glacier, Nepal. For borehole information, see the related datasets.

Data collection:

Borehole tilt and ice deformation sensors installed in 2017 were three-axis analog micromechanical system accelerometers (model MMA7361), controlled by Campbell Scientific CR1000 data loggers from the glacier surface. The sensors were installed so that the z axis recorded approximately 1 g when hanging vertically in the borehole.

The digital sensors installed in 2018 are three-axis accelerometer/three-axes gyroscopes (model MPU6050), and also contain thermistors to measure temperature (model DS18B20), all controlled by a RS-485 data logger. Roll and pitch read values of 0 when the sensor is perfectly vertical hanging in the borehole.

Resolution: The accelerometers installed in 2017 have an accuracy of 800 mV g-1 stated by the manufacturer (where g is the normalised gravity vector). A further calibration was carried out (details in Doyle et al. (2018)), resulting in the absolute accuracy of the tilt sensors being determined to be less than +/- 1 degree.

The digital sensors installed in 2018 also measured temperature, however, these were not calibrated and are therefore only accurate to +/- 0.5 degrees Celsius.

Data quality:

Detailed methodology, including accuracy estimation, is presented in the referenced publication.

Resolution:

The accelerometers installed in 2017 have an accuracy of 800 mV g-1 stated by the manufacturer (where g is the normalised gravity vector). A further calibration was carried out (details in Doyle et al. (2018)), resulting in the absolute accuracy of the tilt sensors being determined to be less than ± 1 degree.

The digital sensors installed in 2018 also measured temperature, however, these were not calibrated and are therefore only accurate to ± 0.5 degrees Celsius.