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Ice thickness and bed elevation of the Northern and Southern Patagonian Icefields

Millan, Romain1; Rignot, Eric1; Mouginot, Jeremie1; Rivera, Andres2

Published Feb 20, 2019; Updated May 02, 2025 on Dryad. https://doi.org/10.7280/D11Q17

Data files

Feb 20, 2019 version files 6.35 MB
Feb 20, 2019 version files 6.35 MB
May 02, 2025 version files 18.07 MB

Abstract

The Northern and Southern Patagonian Icefields are the largest ice masses in the Southern Hemisphere outside Antarctica, but their ice volume and bed topography are poorly known. We combine airborne gravity data collected in 2012 and 2016, with radar data from the Warm Ice Experiment Sounder and Centro de Estudios Científicos's from year 2014 and 1015 to map bed elevation and ice thickness in great detail. We perform a 3-D inversion of the gravity data constrained by radar-derived thickness and fjord bathymetry to infer bed elevation at 500-m spacing, with a precision of about 60 m. We detect deep glacial valleys with ice thickness exceeding 1,400 m and sectors below sea level on the western branch of Glaciar Pio XI, Occidental, between San Rafael and Colonia, and near Fitz Roy. We calculate an ice volume of 4,756 ± 923 cubic kilometers for Northern Patagonia Icefield and Southern Patagonia Icefield, or 40 times the volume of glaciers in the European Alps.

We perform a three dimensional inversion of the gravity field constrained by radar-derived thickness, ice boundary, and fjord bathymetry to infer bed elevation at 500-m spacing, with a precision of about 50 m.

The enclosed netCDF contains the following fields: X: x UTM coordinate (meters), Y: y UTM coordinate (meters), bed: bedrock elevation (meters), misfit: Misfit after inversion (calculated minus observed gravity), misfitm: Converted misfit using a conversion factor of 5.8 mGal per 100m, Source: Data source, 0=bathymetry , 1=gravity, 2=radar depth sounder, and Fulthick: Comprehensive Ice thickness calculated using gravity inversion inside the survey domain and Carrivick 2016 modified outside.

The projection is given as: "PROJCS[\"WGS 84 / UTM zone 18S\",GEOGCS[\"WGS 84\",DATUM[\"WGS_1984\",SPHEROID[\"WGS84\",6378137,298.257223563,AUTHORITY[\"EPSG\",\"7030\"]],AUTHORITY[\"EPSG\",\"6326\"]], PRIMEM[\"Greenwich\",0,AUTHORITY[\"EPSG\",\"8901\"]],UNIT[\"degree\",0.0174532925199433,AUTHORITY[\"EPSG\",\"9122\"]],AUTHORITY[\"EPSG\",\"4326\"]], PROJECTION[\"Transverse_Mercator\"],PARAMETER[\"latitude_of_origin\",0],PARAMETER[\"central_meridian\",-75],PARAMETER[\"scale_factor\",0.9996],PARAMETER[\"false_easting\",500000],PARAMETER[\"false_northing\",10000000],UNIT[\"metre\",1,AUTHORITY[\"EPSG\",\"9001\"]],AXIS[\"Easting\",EAST],AXIS[\"Northing\",NORTH],AUTHORITY[\"EPSG\",\"32718\"]]";

More details in:  Millan, R., Rignot, E., Rivera, A., Martineau, V., Mouginot, J., Zamora, R., et al. (2019). Ice thickness and bed elevation of the Northern and Southern Patagonian Icefields. Geophysical Research Letters, 46, 6626–6635. https://doi.org/10.1029/ 2019GL082485

We also provide shape files of the radar thickness data collected by the NASA/JPL/UCI Warm Ice Sounding Experiment (WISE) in 2014 onboard a fixed-wing airfract and data collected by the CECS radar sounder, Dr. Andres Rivera, PI, on an helicopter. 

For the WISE radar, bed returns were digitized manually and classified with a quality flag that reflected the uncertainty of identification of the bed: Quality 0 = 100 m, 1 = 50 m, and 2 = 25 m. Bed_WISE_20170726_utm18S: Complete data set of bed elevation above mean sea level. Bed_WISE_20170726_Quality0_utm18s: Quality 0. Bed_WISE_20170726_Quality1_utm18s: Quality 1. Bed_WISE_20170726_Quality2_utm18s: Quality 2. For the Rivera data, we do not provide quality labels. Bed_AndresRivera: All bed elevation above mean sea level.

The projection is given as : PROJCS["WGS 84 / UTM zone 18S",GEOGCS["WGS 84",DATUM["WGS_1984",SPHEROID["WGS 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4326"]],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_origin",0],PARAMETER["central_meridian",-75],PARAMETER["scale_factor",0.9996],PARAMETER["false_easting",500000],PARAMETER["false_northing",10000000],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["Easting",EAST],AXIS["Northing",NORTH],AUTHORITY["EPSG","32718"]].