Abstract: Monthly measurements of ice shelf area and exploration of the spatiotemporal characteristics and factors influencing ice shelf extent improve our understanding of the mechanisms of ice shelf collapse. This study uses visual interpretation, coastline transition algorithms, and optical and synthetic aperture radar remote sensing images to extract data on ice shelf extent over the 284 months from January 2000 to August 2023. The periodic and seasonal characteristics of ice shelf area were examined. The influence of the Oceanic Niño index (ONI), the Southern Annular Mode (SAM), sea ice concentration (SIC), and sea surface temperature (SST) on ice shelf extent was analyzed. The results show that: (1) during the 24 years of the study period, the Dalk Ice Shelf experienced six “forward rapid retreat” cycles, each accompanied by strong El Niño or La Niña events. At the end of each cycle, the front edge of the ice shelf retreated to the area dominated by ice ridges with prominent topographical variations. (2) The retreat of the Dalk Ice Shelf exhibited clear seasonality. Retreat area was the largest in summer with maxima in March. In 2016, a strong El Niño year, the ice shelf experienced an abnormally rapid collapse event in winter. (3) Ice shelf area is significantly negatively correlated with SST (r=−0.35, p<0.01) and the magnitude of the correlation coefficient is modest. Ice shelf area is positively correlated with the SAM (r=0.26, p<0.01) with a small correlation coefficient. It is positively correlated with SIC (r=0.57, p<0.01) with a large coefficient. It is also positively correlated with the ONI (r=0.68, p<0.01).

Key words: Dalk Ice Shelf, changes in ice shelf range, influencing factors, response mechanism