Variation of Antarctic marginal ice zone extent (1989–2019)

The Antarctic marginal ice zone (MIZ) is the transition region between open water and consolidated pack ice, which is defined as an area with 15%–80% sea ice concentration. The MIZ represents the outer circle of Antarctic sea ice and the biological activity circle of Antarctic organisms, which provides a direct indication of the extent of Antarctic sea ice. In this study, the joint total variation and nonnegative constrained least square algorithm are applied to retrieve the Antarctic MIZ extent based on passive microwave data sets from 1989 to 2019. The spatial and temporal variations of the Antarctic MIZ extent and five regions are analyzed. The results show that the Antarctic MIZ extent follows a strong monthly variation pattern, decreasing from November to February and increasing from March to October. The annual MIZ extent is largest in the Weddell Sea and smallest in the Western Pacific Ocean. The edge of the sea ice begins to form a closed ring in May, which eventually closes near the Antarctic Peninsula. The ring width variation is large in summer, but generally stabilizes between 350 and 370 km in winter. The average latitude of the Antarctic MIZ is relatively stable in summer, but changes substantially in winter with a difference of approximately 3°. In October, the lowest mean latitude of the MIZ can reach 64.35°S. The sea surface pressure, 2-m temperature, and 10-m wind speed are negatively correlated with the MIZ extent variation, among which the second-order partial correlation coefficient of the sea surface pressure and MIZ extent is −0.8773 in the Western Pacific Ocean