Integrating Microwave Remote Sensing with Physical Models to Reveal Melt Dynamics and Structural Variability in Queen Maud Land

The Queen Maud Land (QML) sector of East Antarctica comprises a complex system of grounded ice sheet and fringing ice shelves that regulate ice discharge to the Southern Ocean. Ice-sheet evolution in this region is controlled by interactions between atmospheric forcing, katabatic winds, and bedrock topography, producing strong spatial variability in accumulation, flow, and thermal regimes. While the bordering ice shelves currently act as stabilising buttresses, they are sensitive to oceanic heat intrusions, changing sea-ice conditions, and episodic surface melt. Melt–refreeze processes enhance firn compaction, weaken surface integrity, and may precondition ice shelves for hydrofracture under future warming, despite QML presently exhibiting a positive mass balance trend.

We investigate the thermal and structural evolution of snow, firn, and ice in QML using an integrated framework that combines multi-frequency passive microwave observations with physically based modelling. Passive microwave measurements provide complementary sensitivity to near-surface melt processes and deeper firn and ice structure, enabling the detection of both contemporary melt signals and long-term subsurface changes. Lower-frequency observations penetrate deep into the firn and ice column, whereas higher-frequency observations respond to surface temperature, liquid water content, and accumulation variability.

Snow, firn, and ice evolution is simulated using the Glacier Energy and Mass Balance (GEMB) model, running on the Ice Sheet and Sea Level System Model (ISSM), providing vertical profiles of temperature, density, and liquid water content driven by meteorological forcing. These profiles are used to forward-model microwave brightness temperatures with the Microwave Emission Model of Layered Snowpacks (MEMLS) across frequencies from 1.4 to 36.5 GHz, accounting for densification and refrozen ice layers. Modelled brightness temperatures are evaluated against satellite observations, providing twice-daily coverage of QML since 2010.

We present spatial and temporal patterns of grounded ice-sheet structure, surface and subsurface temperature variability, fresh snow accumulation, and ice shelf melt signatures, together with residuals between observed and modelled brightness temperatures. Our results demonstrate the value of radiometric modelling for constraining firn structure, melt processes, and ice-shelf vulnerability in regions with sparse in situ data. By integrating passive microwave observations with physical firn models, this work supports improved calibration, initialisation, and confidence in projections of mass balance and structural evolution in the Queen Maud Land sector of East Antarctica.