Camp Century: Firn compaction measurements (CEN-COM)

• Main Authors: Colgan, William, Vandecrux, Baptiste
• Format: Dataset
• Language: unknown
• Published: GEUS Dataverse 2021
• Subjects: Antarctic; Greenland; Pedersen; Whillans; Antarc*; Ice Sheet
• Online Access: https://dx.doi.org/10.22008/fk2/cqsklk; https://dataverse01.geus.dk/citation?persistentId=doi:10.22008/FK2/CQSKLK

Firn compaction measurements at Camp Century (CEN-COM) Contact: Baptiste Vandecrux ([e-mail]) Please cite the following study when using these data: Vandecrux, B., Colgan, W., Solgaard, A.M., Steffensen, J.P., and Karlsson, N.B.(2021). Firn evolution at Camp Century, Greenland: 1966-2100, Frontiers in Earth Science, https://doi.org/10.3389/feart.2021.578978, 2021 Location: 77.18N -61.11E 1886 m a.s.l Temporal coverage: 2017-08-01 to 2020-01-19 Temporal resolution: daily snapshots Instrument design: The instrument were designed by Mike MacFerrin ([e-mail]) after “coffee-can” method (Hulbe and Whillans, 1994; Hamilton et al., 1998) to continuously monitor firn compaction, similar to the method used by Arthern et al. (2010). Each instrument is composed of a line with a weight attached to one end and connected to a spring-loaded potentiometer on the other end. The weight is anchored at the bottom of a borehole, and the potentiometer is placed at the top of the borehole. As the borehole shortens due to firn compaction, the potentiometer reels in the string to maintain tension, and a data logger records the length of string that has been reeled in. The CEN-COM station was first introduced by Colgan et al. (2018) and then described and used in Vandecrux et al. (2021). Please consider citing these two studies if using this data. References: Arthern, R.J., Vaughan, D.G., Rankin, A.M., Mulvaney, R., and Thomas, E.R. (2010). In situ measurements of Antarctic snow compaction compared with predictions of models. J. Geophys. Res. 115, 12 PP. Colgan, W., Pedersen, A., Binder, D., Machguth, H., Abermann, J., and Jayred, M. (2018). Initial field activities of the camp century climate monitoring programme in Greenland. Geol. Surv. of Denmark Greenland Bull. 41, 75–78. doi:10.34194/geusb.v41.4347 Hamilton, G.S., and Whillans, I.M. (2002). Local rates of ice-sheet thickness change in Greenland. Ann. Glaciol. 35, 79–83. Hulbe, C., Whillans, I. (1994). A method for determining ice-thickness change at remote locations using GPS. Annals of Glaciology, 20, 263-268. doi:10.3189/1994AoG20-1-263-268 Vandecrux, B., Colgan, W., Solgaard, A.M., Steffensen, J.P., and Karlsson, N.B.(2021). Firn evolution at Camp Century, Greenland: 1966-2100, Frontiers in Earth Science, https://doi.org/10.3389/feart.2021.578978, 2021 Instrumental set up: On 1st of August 2017, three instruments were installed: Instrument #1: Top at 1.4 m depth, end of line at 62.3 m depth Instrument #2: Top at 0.0 m depth, end of line at 20.0 m depth Instrument #3: Top at 0.0m depth, end of line at 5.0 m depth On the 16th of May 2019, these three intruments were unplugged and two new instruments were inserted: Instrument #1: Top at 0.0 m depth, end of line at 4.9 m depth (+/- 0.2 m) Instrument #2: Top at 0.0 m depth, end of line at 7.7 m depth (+/- 0.2 m) Instrument #5 failed and did not record any data. Field operators: Liam Colgan, Robert S. Fausto, Allan Ø. Pedersen Data description: This folder contains transmissions from the station modem. The three useful columns are the last three: "INST_1_LENGTH_CORRECTED_M" (and INST_2, INST_3, respectively). This shows the length of the 2-m potentiometer cable over time. To derive borehole length from these measurements, do this: INIT_BOREHOLE_LEN = depth (m) of the borehole when it was first drilled at the instrument installed. INIT_CABLE_LEN = length of the cable (m) at the first full day after the instrument was installed (can check your field notes, or just plot look at the data to see when the trends begin), from the table CURRENT_CABLE_LEN = length of the cable (m) on any subsequent day CURRENT_BOREHOLE_LEN = length of the borehole (m) on any subsequent day Calculate as such: CURRENT_BOREHOLE_LEN = INIT_BOREHOLE_LEN - INIT_CABLE_LEN + CURRENT_CABLE_LEN The first weeks of measurements can be affected by the initial settling of the instrument into the snow.