Widespread seawater intrusions beneath the grounded ice of Thwaites Glacier, West Antarctica

Warm water from the Southern Ocean has a dominant impact on the evolution of Antarctic glaciers and in turn on their contribution to sea level rise. Using a continuous time series of daily-repeat satellite synthetic-aperture radar interferometry data from the ICEYE constellation collected in March-June 2023, we document an ice grounding zone, or region of tidally-controlled migration of the transition boundary between grounded ice and ice afloat in the ocean, at the main trunk of Thwaites Glacier, West Antarctica, a strong contributor to sea level rise with an ice volume equivalent to a 0.6-m global sea level rise. The ice grounding zone is 6 km wide in the central part of Thwaites with shallow bed slopes, and 2 km wide along its flanks with steep basal slopes. We additionally detect irregular seawater intrusions, 5-10 cm in thickness, extending another 6 km upstream, at high tide, in a bed depression located beyond a bedrock ridge that impedes the glacier retreat. Seawater intrusions a..., Differential interferometry measures a differential change in ice displacement between 3 (or 4) epochs after eliminating the horizontal motion of ice through differencing of two pairs: we subtract two consecutive one-day pairs to eliminate the (steady) horizontal motion of the ice and leave the short term (vertical) motion of the ice, i.e. the vertical motion caused by changes in oceanic tide and atmospheric pressure, plus noise. If there is a data gap in data acquisition, we combine 2 x 1-day pairs acquired more than one day apart, hence 4 scenes. 
Predictions of SSH. We calculate changes in SHH using the CATS2008 tidal model corrected for IBE using ERA-5 atmospheric pressure fields.  
Subglacial hydrology is reproduced using the 2D finite-element Glacier Drainage System (GlaDS) model, which predicts the presence of long, high-pressured subglacial channels and an adjacent distributed drainage system. GlaDS calculates water discharge, flux, and pressure beneath Thwaites Glacier. The mod..., , # Widespread seawater intrusions beneath the grounded ice of Thwaites Glacier, West Antarctica

## Description of the data and file structure

All the data are geocoded in Polar Stereographic format, with a coordinate reference system (CRS) EPSG:3031, at 25 m posting.

1. Three differential_interferograms folders: 1) AscRight, 2) AscLeft, and 3) DscRight.
* The differential interferograms are 27 in descending right-looking, 26 in ascending right-looking, and 20 in ascending left-looking tracks. The naming convention is \"gl_ICEYE-X6_9999_9999_ASC_YYYYMMDD_HHMMSS-YYYYMMDD_HHMMSS_YYYYMMDD_HHMMSS-YYYYMMDD_HHMMS_XXXXX_XXXX_XXXXX_XXXXX_2s.tiff\". The first \"YYYYMMDD_HHMMSS_HHMMSS\" stands for the date and time of the primary interferogram. The second \"YYYYMMDD_HHMMSS_HHMMSS\" after hyphen \"-\" stands for the date and time of the secondary interferogram. XXXX is several seconds in the day for the 4 dates. tiff means geotiff format. The projection is ESPG 3031 WGS 84 Antarctic Polar Stereogr...