Distinct Seasonal Flow Pattern of Byrd Glacier, East Antarctica

Abstract Understanding ice dynamics across varying temporal scales is essential for accurately assessing the contribution of the Antarctic Ice Sheet to global sea level rise. Investigations of seasonal timescale ice dynamics illuminate how glaciers respond to environmental forcings and improve the accuracy of discharge‐based mass balance estimates. Here, we generated a high‐precision, monthly ice velocity field for Byrd Glacier by combining ITS_LIVE image‐pair products with ALOS‐2 offset tracking measurements. We then applied seasonal signal detection methods to systematically analyze the ice velocity variations. Our results reveal a distinctive dipole‐like seasonal flow pattern of Byrd Glacier: from austral spring through summer, ice velocities decrease by an average of ∼40 m/yr in the grounding zone, while flow speeds on the downstream ice shelf increase by ∼20 m/yr. Empirical orthogonal function (EOF) analysis indicates that these seasonal variations are primarily governed by physical processes operating at the grounding zone. We propose that the dipole signal is best explained by interactions between seasonal incursions of high‐salinity shelf water (HSSW) and the subglacial hydrological system. Although sea surface height anomalies have been suggested as a potential driver, their modeled amplitudes and in‐phase patterns indicate that they are unlikely to be the dominant contributors. In contrast, the HSSW–subglacial hydrology framework provides a consistent explanation for both the velocity magnitude and the out‐of‐phase behavior. Although further observations and modeling are needed, findings highlight the complexity of Antarctic glacier seasonality and the need for improved observations and coupled modeling to clarify mechanisms and implications for ice sheet mass balance.