Researchers using satellite data have documented the drainage of the Kronshtadskiy (also spelled Kroushtadskiy) subglacial lake in East Antarctica near the Amery Ice Shelf, which caused a broad depression in the overlying ice surface that deepened by more than 6 meters (about 20- 21 feet) at its center.
The lake, previously hidden under the ice, lost an estimated 78 million cubic meters (roughly 20.6 billion gallons) of water between 2016 and 2021. This volume is equivalent to tens of thousands of Olympic- sized swimming pools. The affected surface area was roughly circular and covered about 61 square kilometers (24 square miles). Average surface lowering across the area was about 1.3 meters (4.3 feet).
Key details from the study (published in Scientific Reports by Jihyun Moon and Hoonyol Lee of Kangwon National University, South Korea):
- Most drainage happened early: the center sank about 3.8 meters (12.5 feet) in 2016- 2017, then slowed markedly (to under 0.3 meters per year by 2019–2021), with little evidence of major refilling. This pattern points to prolonged or repeated partial drainage through subglacial channels rather than one sudden catastrophic outburst.
- Analysis relied primarily on Sentinel-1 SAR (synthetic aperture radar) interferometry, which detects millimeter- scale surface changes from space, supported by CryoSat- 2 and ICESat- 2 altimetry data.
- Downstream surface features (one rising, another sinking) suggest the water may have moved into a connected network of other subglacial reservoirs rather than simply vanishing.
Subglacial lakes form from meltwater generated by geothermal heat and friction at the ice- bedrock interface.
Active ones fill and drain over months to years, influencing ice- sheet flow by lubricating the base and potentially affecting how ice reaches the ocean. This event adds to growing satellite- based inventories of such lakes (hundreds are now known across Antarctica) and helps map hidden hydrologic networks.
The findings highlight how remote sensing can reveal dynamic processes under kilometers of ice that would otherwise be inaccessible.
Double- Differential Interferometric Synthetic Aperture Radar (DDInSAR) is an advanced remote- sensing technique that measures subtle, time- varying vertical surface displacements, especially useful for detecting activity of subglacial lakes under Antarctic ice sheets.
How it builds on standard InSAR methods
| Technique | What it does | Main signal isolated |
|---|---|---|
| InSAR | Compares the radar phase of two SAR images of the same area acquired at different times (or slightly different positions) | Topography, surface motion, atmosphere and noise |
| DInSAR (Differential InSAR) | Removes the topographic contribution (using a DEM or a second interferometric pair) | Surface deformation (line- of- sight), which still mixes horizontal ice flow and vertical changes |
| DDInSAR (Double-Differential InSAR) | Differentiates two DInSAR interferograms from different time periods | Temporally varying vertical displacement (the steady horizontal ice- flow component largely cancels out) |
Why DDInSAR is needed on ice sheets
On fast- flowing Antarctic glaciers, the dominant signal in a normal DInSAR interferogram is the steady horizontal ice motion. Subglacial lake filling or drainage produces a much smaller vertical (up and down) signal that is mixed in with the flow.
If ice- flow velocity is approximately constant between the two periods, subtracting one DInSAR interferogram from another cancels the common flow contribution. What remains are closed contour “fringes” that map the change in vertical displacement rate, exactly the signature of a lake rising or falling.
Practical application (as used for Kronshtadskiy lake)
- Researchers form many short- baseline (e.g., 24-day) Sentinel- 1 DInSAR pairs.
- They then create DDInSAR interferograms by differencing pairs from different epochs.
- The resulting maps reveal a roughly circular zone of progressive surface sinking (up to ~6.4 m at the center over several years), from which water- volume loss can be estimated.
- Complementary ascending and descending orbits or altimetry (CryoSat- 2, ICESat- 2) can further separate residual horizontal- flow variations if needed.
Advantages and limitations
- Strengths: High spatial resolution, sensitivity to millimeter- to- centimeter vertical changes, works through cloud and polar night, and can detect relatively small or short- lived hydrological events that altimetry alone might miss.
- Assumptions: Ice- flow velocity must be reasonably steady; otherwise, residual flow- variation signals must be modeled and removed.
- Coherence: Requires sufficient radar coherence (surface stability) between acquisitions; long temporal baselines or heavily crevassed ice can degrade results.
In short, DDInSAR is a clever “double differencing” of radar phase measurements that isolates the vertical “breathing” of the ice surface caused by hidden subglacial water movement.
Drainage of Kronshtadskiy subglacial lake in Antarctica observed by double-differential SAR interferometry
Abstract summary
Hundreds of subglacial lakes in Antarctica have been identified via radio- echo sounding and satellite altimetry but detecting smaller or shorter- lived hydrological events has been difficult because of limited spatial and temporal resolution. This study applied Double- Differential Interferometric Synthetic Aperture Radar (DDInSAR) to measure surface- elevation changes linked to the Kronshtadskiy subglacial lake near the Amery Ice Shelf in East Antarctica.
Researchers generated 77 DDInSAR interferograms from Sentinel- 1 SAR images (24- day temporal baseline) spanning 2016- 2021. They documented a rapid drainage event at a roughly circular subglacial lake covering 61 km². Estimated water- volume loss was 78.0 million cubic meters (Mm³).
- Maximum subsidence at the lake center: 6.37 m.
- Most of the drop occurred in 2016– 2017 (rate ≈ 2.54 m/yr).
- Rates then declined sharply: 0.88 m/yr in 2018 and < 0.30 m/yr during 2019–2021.
Independent satellite altimetry from CryoSat-2 and ICESat-2 confirmed the overall subsidence trend. The work shows that DDInSAR is effective for monitoring subglacial hydrology even in fast- flowing polar ice environments.
Additional details from the page
- Funding: National Research Foundation of Korea and related Korean technology programs.
- Corresponding author: Hoonyol Lee (hoonyol@kangwon.ac.kr).
- Open-access under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 license.
- Received 7 April 2026; accepted 9 October 2026.
This is the primary peer- reviewed source behind the recent news reports about the “sinking Antarctic ice” and the lake’s water loss.
The DDInSAR method provided higher- resolution spatial mapping of the surface depression than altimetry alone, allowing the volume estimate and the temporal evolution of the drainage to be reconstructed in detail.
Journal: Scientific Reports, (2026), Open access
DOI: 10.1038/s41598-026-75829-x
Published: 12 October 2026 (early access, accepted version)
Authors: Jihyun Moon & Hoonyol Lee
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