Autonomous phase sensitive radar (ApRES) on Amery Ice Shelf 2015-2018

Full description

Raw data from two autonomous phase sensitive radar (ApRES) installations on Amery Ice Shelf, East Antarctica.

Site, Lat, Lon, Installation, Retrieval
AM06_borehole, -70.228432, 71.391693, 17-Jan-2015, 03-Feb-2018
AM06_downstream, -70.225635, 71.395988, 09-Mar-2015, 03-Feb-2018

ApRES phase-sensitive radar is a low-power, light-weight instrument developed in a collaboration between BAS and University College London. It is a 200-400 MHz FMCW radar, with a 1-second chirp, run by controller. Each radar was set to produce a burst of 50 chirps every 4 hrs, and a config file with radar settings is provided with each dataset.

Files:
*.dat - binary files containing raw data
config.ini - config file containing all radar settings used for each site

Software for processing the raw data can be obtained from Dr. Keith Nicholls, British Antarctic Survey. Limited Matlab scripts are provided here to open the raw data.

Command: f=fmcw_load('filename.DAT')

Data structure:
Variable name Unit Description
Nattenuators - Number of attenuation settings used (1 or 2)
Attenuator_1 dB RF Attenuator value 1
Attenuator_2 dB RF Attenuator value 2
ChirpsInBurst - Number of chirps in burst
TimeStamp day Time of first chirp (Matlab date format)
Temperature_1 C Instrument temperature 1
Temperature_2 C Instrument temperature 2
BatteryVoltage V Battery voltage
Burst - Number of burst in file
FileFormat - Identifies file format from different equipment versions
vif V Voltage
chirpTime day Time of chirp (Matlab date format)
filename - Filename
SamplesPerChirp - Number of samples per chirp
fs Hz Sampling frequency
f0 Hz Start frequency
K rad/s/s Chirp gradient (200MHz/s)
f1 Hz Stop frequency
B Hz Bandwidth
fc Hz Centre frequency
er - Material permittivity
ci m/s Velocity in material
lambdac m Centre wavelength
t s Sampling time (relative to first sample)
f Hz Frequency stamp for sample

Lineage

Progress Code: completed

Statement: Due to inappropriate attenuation settings there is some clipping of the radar signal. Processing should be applied only to a restricted frequency range of 320 – 400 MHz. The temperatures recorded are from two temperature sensors on the radar board, one near the clock, and one near the active filter. They can be used as an indicator of when temperature-sensitive components may encounter faults, but should not be considered representative of local air temperatures.

Notes

Purpose
These data can be used to measure total thickness change, internal strain rates, and melt at the base of the ice sheet. See: Brennan, P. V., Lok, L. B., Nicholls, K., and Corr, H. (2014). Phase-sensitive FMCW radar system for high-precision Antarctic ice shelf profile monitoring. IET Radar, Sonar and Navigation, 8(7), 776-786. Nicholls, K. W., Corr, H. F., Stewart, C. L., Lok, L. B., Brennan, P. V., and Vaughan, D. G. (2015). A ground-based radar for measuring vertical strain rates and time-varying basal melt rates in ice sheets and shelves. Journal of Glaciology, 61(230), 1079-1087.