Sea Ice Concentration Changes Research Articles

The influences of atmospheric half‐yearly cycle on the sea ice extent in the Antarctic

The relationship between sea ice and weather, one of the least known components of the climatic system, could be an important factor for the climate of high latitudes. The annual cycle of the sea ice extent is characterized by a asymmetric development, with the sea ice area slowly advancing toward the equator in the winter and rapidly retreating in summer. In this study the seasonal asymmetric behavior of ice extent and the changes in sea ice concentration are shown to be linked to the atmospheric convergence line (ACL) around Antarctica. It is found that the relative positions of the ACL characterized by the half‐year cycle exert a strong influence upon the mean movement of the sea ice. It is also observed from the investigations of the areal concentration of the sea ice that a decrease in ice concentration prior to the sea ice retreat is needed for a rapid retreat.

Sea Ice–Atmosphere Signal of the Southern Oscillation in the Weddell Sea, Antarctica

Abstract Composite analysis of weekly ship and shore observations of the Weddell Sea pack ice for extreme events of the Southern Oscillation (SO) occurring in the 1929–62 period reveals strong variations in ice-water concentrations in the early and late summer melt season. Substantially reduced ice concentrations (more open water) occur in December and early January of “warm” (El Nino) events (yr0) compared with the summer before (yr−1), and appear connected with the change to a stronger cyclonic atmospheric circulation over higher latitudes of the South Atlantic. Similarly consistent meteorology-sea ice associations appear to characterize the mid- to late summer of warm SO events (yr0) compared with yr0 of “cold” events. There is some evidence that the regionally dependent pressure and wind reversals (and possibly the associated sea ice concentration changes) in the Weddell sector have become more marked during SO events occurring since about the early 1950s. Some corroboration of changes in the sea ice-...