The datasets are ice tilt time series from strings of accelerometers, each located at a discrete depth within one of three boreholes into Khumbu Glacier, Nepal. Ice deformation can be derived from this tilt data, but has not yet been calculated. Boreholes were drilled in May 2017 and 2018 to investigate the internal properties of Khumbu Glacier, specifically ice thickness, temperature, deformation and structure, as part of the NERC-funded 'EverDrill' research project. Supporting borehole information is provided as a related dataset.
Funding was provided by the NERC grant NE/P00265X/1 and NE/P002021/1.
***** PLEASE BE ADVISED TO USE VERSION 2.0 DATA *****
The VERSION 2.0 data set (see 'Related Data Set Metadata' link below) which contains an additional 11 months of measurements.
Ice boreholes, Ice deformation, Khumbu Glacier, Nepal
|Access Constraints:||No restrictions apply.|
|Use Constraints:||This data is governed by the NERC data policy http://www.nerc.ac.uk/research/sites/data/policy/ and supplied under Open Government Licence v3.0 http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/.|
|ISO Topic Categories:||
|Name||UK Polar Data Centre|
|Organisation||British Antarctic Survey|
|Role(s)||Investigator, Technical Contact|
|Organisation||University of Leeds|
|Organisation||University of Leeds|
|Reference:||Doyle, S.H., Hubbard, B., Christoffersen, P., Young, T.J., Hofsteded, C., Bougamont, M., Box, J.E., and Hubbard, A. (2018), Physical conditions of fast glacier flow: 1. Measurements from boreholes drilled to the bed of Store Glacier, West Greenland, Journal of Geophysical Research: Earth Surface, 123, doi.org/10.1002/2017JF004529|
|Quality:||Detailed methodology, including accuracy estimation, is presented in the referenced publication.
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.
|Lineage:||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 Set Creator||Hubbard, Bryn; Miles, Katie; Doyle, Samuel; Quincey, Duncan; Miles, Evan|
|Data Set Title||Ice tilt time-series from sensors installed in boreholes drilled into Khumbu Glacier, Nepal, in 2017 and 2018 as part of EverDrill research project|
|Data Set Release Date||2019|
|Data Set Publisher||Polar Data Centre,Natural Environment Research Council,UK Research & Innovation|
|Other Citation Details||shortdoi:10/c4bb|
|Detailed Location||Khumbu Glacier, Himalaya|
|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.
|Data Storage:||The data are structured in three comma-separated ASCII files (*.csv format), one for each borehole accelerometer string. Each file is ~3 MB in size. Each file holds the data for a single borehole.
For the accelerometers installed in 2017, each column presenting a different accelerometer (labelled by depth from the glacier surface, in metres; see Instrumented Borehole Info), and each row the date and time at which the tilt reading (degrees) was recorded.
For the digital sensors installed in 2018, each row also contains the date and time at which the readings were made. 'PTemp' contains the logger temperature in degrees Celsius. 'vcc#' refers to the supply voltage of each sensor (volts); 'T#' the uncalibrated temperature recorded by each sensor; 'r#' to the roll of each sensor (degrees); 'r_sigma#' to the standard deviation of roll of each sensor (degrees); 'p#' to the pitch of each sensor (degree); and 'p_sigma#' to the standard deviation of pitch of each sensor (degrees), with each # referring to the sensor number (see Instrumented Borehole Info, under related datasets). 'NaN' values refer to missing data.