Byrd Glacier processed geodetic grounding line data
This dataset is from field work conducted at Byrd Glacier, East Antarctica. Global positioning system (GPS) receivers were deployed over the trunk of the glacier as well as two additional units over subglacial lakes in the catchment basin. The dataset here covers two regions. The first is the grounding line where nine receivers were positioned about the grounding line to identify where tidal flexure was occurring during the 2011/12 Austral summer. The second region is Byrd Glacier's catchment basin where two subglacial lakes are hypothesized to be situated. A GPS receiver was deployed on each and the data available here covers the timeline of February 2011 to the end of January 2013. The map included with the downloadable files highlights the locations of the sites. The deployment sites were equipped with Trimble NetR9, 5700, or R7 receivers with Trimble Zephyr antennae. The collected geodetic data is of dual-frequency carrier-beat phase observations which reveals large (~1 m at the grounding line) vertical motion at the ice surface due to the vertical displacement of water at the bed both from tidal fluctuations and the draining and filling of water in the subglacial lakes. The data contain the time of data collection and the positions (XYZ) of the receivers in meter units. The provided GPS grounding line data is sampled at every 5 minutes and the lake GPS data at every 24-hours. The estimated uncertainties of the vertical positions is 2--5 cm which was determined from geodetic data collected at static rock sites surrounding the trunk of the glacier. It is important to stress that this dataset is processed geodetic data and not raw receiver independent exchange format (RINEX) files for the specified timeline. This work was funded by NSF grants ANT0944087 and ANT1255488. *The included map has a hillshade background created from REMA data (https://www.pgc.umn.edu/data/rema/) downloaded from the Polar Geospatial Center.
Steps to reproduce
The geodetic data was collected from the surface of Byrd Glacier, East Antarctica, at the grounding zone and from the catchment basin. The raw data RINEX files were prepared using the GIPSY software (Lichten and Boarder, 1987) and high-precision kinematic data processing techniques (e.g., Elosegui et al., 1996, 2006) to estimate the positions of the GPS sites relative to static data points every five minutes for the grounding zone receivers. Satellite orbits from the International GNSS Service were also employed, but provided no additional improvement to positional determinations. The data was adjusted using stochastic-filter-smoothed time-dependent 3D a priori values via surrounding static rock site positions. The a priori information was also used to determine the weighted root-mean-square scatter of the collected data's measured vertical component. A conservative estimate of the vertical error of this dataset is ~5 cm. Citations: --Elósegui, P., Davis, J. L., Johansson, J. M., & Shapiro, I. I. (1996). Detection of transient motions with the Global Positioning System. Journal of Geophysical Research: Solid Earth,101(B5), 11249–11261. --Elósegui, P., Davis, J. L., Oberlander, D., Baena, R., & Ekström, G. (2006). Accuracy of high-rate GPS for seismology. Geophysical Research Letters, 33(11). --Lichten, S. M., & Border, J. S. (1987). Strategies for high-precision Global Positioning System orbit determination. Journal of Geophysical Research: Solid Earth, 92(B12), 12751–12762.