DOI: 10.5061/dryad.k0p2ngfgt
title: Data from: Rapid retreat of Berry Glacier, West Antarctica linked to seawater intrusions revealed by radar interferometry

description: We employ a time series of ERS-1/2, ALOS-2 PALSAR, Sentinel-1, and
 COSMO-SkyMed differential synthetic-aperture radar interferometry data
 from 1996 to 2021 to document the short-term and long-term migrations of
 the grounding line (GL) of Berry Glacier, West Antarctica, a major
 tributary of Getz Ice Shelf that controls 10 % of its ice discharge. We
 detect a short-term migration of 18.0 ± 0.9 km with changes in oceanic
 tide, which translates into a major revision of the bed topography to
 reveal a subglacial valley 1,300 m deeper than previously known. The
 migration is not in phase with the tide and oscillates between three
 states controlled by spatial variations in bed topography. Seawater
 intrusions alternate with extrusions and trapping of seawater. During
 1996-2021, the GL retreated more than 18 km, or 0.7 km/yr, ice thickness
 decreased by 11 ± 1 m/yr, the glacier sped up by 64 ± 5%, and the mass
 loss totalled 131 ± 23 Gt. We attribute the retreat to enhanced heat flux
 from warm Circumpolar Deep Water (CDW) via favorable bathymetric channels
 and km-sized seawater intrusions beneath the glacier. Interaction with a
 complex bed topography, however, limited the efficiency of the ocean at
 carving a new cavity and forcing a more rapid retreat.
description: # Title of Dataset: Rapid retreat of Berry Glacier, West Antarctica linked
 to seawater intrusions revealed by radar interferometry --- This dataset
 contains drainage basin utilized to compute surface mass balance; flux
 gates for ice discharge calculation of three time periods; grounding line
 (GL) shapefiles mapped based on corresponding double-difference
 interferograms covering Berry Glacier over period 1996-2021; grounding
 zone (GZ) shapefile made up with the most retreated and the least
 retreated GLs; profile shapefile along GL migration direction used to
 calculate bed, surface, thickness, ice speed, surface height change, and
 furthermore GZ width from hydrostatic equilibrium; GL density map; pinning
 points derived from the interferograms; and analysis about GL migration
 vs. tidal height and changes in surface height/flow speed/mass balance. ##
 Description of the Data and File Structure All the shapefiles and maps can
 be opened in QGIS or other similar GIS softwares. Recommended coordinate
 reference system to open the data is EPSG:3031 - WGS 84 / Antarctic Polar
 Stereographic. **Table of Contents** * drainage basin * flux gates * GL
 shapefiles * GZ shapefiles * line density * pinning points * profile
 shapefile * GL analysis, tidal heights, speed & surface height.xlsx
 **File/Folder Details** *Details for: drainage basin* * Description: a
 folder containing a drainage basin shapefile of Berry Glacier showing the
 region where surface mass balance is computed. * Format(s): .shp *
 Size(s): 3.38 KB *Details for: flux gates* * Description: a folder
 containing three flux gate shapefiles of Berry Glacier showing the cross
 section positions where ice discharge is calculated. Flux gate A-B is for
 the year 1996, flux gate C-D is for the time period 2006-2011, and flux
 gate E-F is for the time period 2012-2022. * Format(s): .shp * Size(s):
 2.59 KB *Details for: GL shapefiles* * Description: a folder containing
 two subfolders: "GL individuals" and "GL collection".
 The first subfolder respectively includes 2 GLs of ERS-1/2, 5 GLs of ALOS
 PALSAR, 57 GLs of Sentinel-1, and 24 GLs of COSMO-SkyMed covering Berry
 Glacier for the years 1996, 2008-2009, and 2019-2021, which are mapped
 based on the correspond high-quality double-difference interferograms. The
 second subfolder contains GL collections for the each years. The
 double-difference interferograms are generated with 3 or 4 radar images
 from ERS-1/2, ALOS PALSAR, Sentinel-1, and COSMO-SkyMed satellites. As
 phase quality in the interferograms is not uniform across the scene, GL
 mapping is not always complete in the 88 interferograms. * Format(s): .shp
 * Size(s): 11.2 MB *Details for: GZ shapefiles* * Description: a folder
 containing the GZ shapefiles of Berry Glacier showing annual GL migration
 boundaries during 2019-2021 as well as three-year total boundary. *
 Format(s): .shp * Size(s): 38.0 KB *Details for: line density* *
 Description: a folder containing the line density map generated with the
 GLs. The line density interpolation calculates a density measure of linear
 features which is obtained in a circular neighborhood within each raster
 cell. It shows the frequency of GL positions between 2019 and 2021. *
 Format(s): .tif * Size(s): 4.36 MB *Details for: pinning points* *
 Description: a folder containing a pinning point shapefile in the GZ of
 Berry Glacier showing the locations where the glacier is partially
 grounding and the direction of water flushing in/out is changed. It's
 dervied based on 15 interferograms. * Format(s): .shp * Size(s): 12.0 KB
 *Details for: profile shapefiles* * Description: a folder containing a
 profile indicating the location where the bed, surface and thickness are
 calculated from BedMachine Antarctica v3.7, the ice bottoms are computed
 from WorldView and ICESat-2 DEMs, and GZ width of hydrostatic equilibrium
 is calculated. It's along the direction of the GL migration. *
 Format(s): .shp * Size(s): 1.60 KB *Details for: GL analysis, tidal
 heights, speed & surface height.xlsx* * Description: a file containing
 information about acquisition time and number of fringes of the
 double-difference interferograms of Sentinel-1 and COSMO-SkyMed; GL
 migration along Berry Glacier; tidal height at the acquisition time of the
 double-difference interferograms, which is calculated from CATS2008 tide
 model with inverse barometer effect (IBE) correction computed from ERA5;
 comparision between differential displacement in DInSAR and differential
 tide height with IBE, which indicates the DInSAR method and the tide model
 both are reliable; bed from BedMachine v3.7, ice bottoms computed from
 WorldView and ICESat-2 DEMs, and OIB ice bottoms along the profiles; speed
 and surface height along the profiles from 1996 to 2022; and discharge,
 surface mass balance, and total mass balance in time serier over
 1996-2022. Cells marked with "n/a" are because of lacking of
 information. Below is a detailed description of each sheet and its
 variables. * Format(s): .xlsx * Size(s): 370 KB * Sheet 1: GL analysis
 & tidal heights This sheet contains records of grounding line and
 associated tidal heights. Variables: Datetime1, Datetime2, Datetime3,
 Datetime4 – Time stamps (UTC) for consecutive satellite acquisitions.
 Format: YYYY-MM-DD hh:mm:ss. mid-time – Midpoint time between acquisition
 pairs (UTC). positive error (days) – Positive uncertainty of the temporal
 separation. negative error (days) – Negative uncertainty of the temporal
 separation. number of fringes – Count of interferometric fringes detected.
 differential displacement (cm) in DInSAR – Line-of-sight differential
 displacement between image pairs (centimeters). differential tide height
 (cm) – Modeled differential tide height from CATS2008 tide model bewteen
 image pairs (centimeters). GL migration_Berry (m) – Grounding line
 migration compared with 1996 grounding line position for Berry Glacier
 (meters). positive error (m) – Positive uncertainty of the grounding line
 migration. negative error (m) – Negative uncertainty of the grounding line
 migration. tide1–tide4 (cm) – Modeled tide height from CATS2008 tide model
 at four timestamps. pressure1–pressure4 (Pa) – Modeled atmospheric
 pressure values at four timestamps. IBE1–IBE4 (cm) at 50/100 km – Inverse
 barometer effect (IBE) correction values (centimeters) at 50/100 km from
 grounding line. tide1+IBE1 – tide4+IBE4 (cm) – Combined ocean tide height
 plus IBE correction (centimeters). maximum tide height (cm) with IBE at
 50/100 km – Maximum corrected tide height (centimeters). * Sheet 2: bed
 & surface elevations This sheet provides cross-section profiles of
 glacier geometry along grounding line migration transects. Variables:
 profile along the direction of GL migration – Profile identifier. distance
 (m) – Along-flow distance from a reference point (meters). bed (m) – Bed
 elevation relative to sea level (meters; negative values indicate below
 sea level). REMA surface (m) – Surface elevation from REMA DEM (meters).
 WorldView ice bottom (m) – Ice base elevation derived from WorldView
 stereo data (meters). ICESat-2 ice bottom (m) – Ice base elevation derived
 from ICESat-2 altimetry (meters). ATM surface (m) – Surface elevation from
 NASA Airborne Topographic Mapper (ATM) lidar (meters). DEM ice bottom (m)
 – Ice base elevation from DEM (meters). OIB ice bottom (m) – Ice bottom
 elevation from Operation IceBridge radar (meters). * Sheet 3: surface
 height This sheet contains time series of ice surface elevation profiles
 along a grounding line migration transect. Variables: distance along the
 direction of GL migration (m) – Along-flow distance (meters). Year
 YYYY_surface height (m) – Surface elevation (meters) at given year from
 remote sensing data. Each column corresponds to a specific year (e.g.,
 1996, 1997, …, 2022). * Sheet 4: speed This sheet contains glacier surface
 velocity profiles along a grounding line migration transect. Variables:
 distance along the direction of GL migration (m) – Along-flow distance
 (meters). Year YYYY_speed (m/yr) – Surface velocity (meters per year) for
 each year (1996, 2006, 2008, 2009, 2010, 2011, 2012, 2014, 2015, 2016,
 2017, 2018, 2019, 2020, 2021, 2022). * Sheet 5: mass balance This sheet
 provides annual glacier mass balance estimates, combining discharge and
 surface mass balance data. Variables: Year – Calendar year of the
 measurement. δDischarge (Gt) – Change in ice discharge relative to
 baseline (gigatonnes). SMB (Gt) – Surface mass balance in gigatonnes per
 year. δSMB (Gt) – Change in SMB relative to baseline (gigatonnes). δM (Gt)
 – Net mass balance anomaly (gigatonnes). cumulative δDischarge (Gt) –
 Cumulative discharge anomaly relative to baseline (gigatonnes). cumulative
 δSMB (Gt) – Cumulative SMB anomaly relative to baseline (gigatonnes).
 cumulative δM (Gt) – Cumulative net mass balance anomaly (gigatonnes). SMB
 1979–2004 (Gt) – Long-term mean surface mass balance over 1979–2004
 (gigatonnes).