Intraseasonal Sea Ice Concentration Variability Over the Weddell Sea During Austral Autumn.

The sea ice concentration (SIC) over the Weddell Sea displays obvious intraseasonal variability during austral autumn with a dominant frequency of 5–20 days. The intraseasonal SIC variability is manifested as development of sea ice anomalies from the northeastern Antarctic Peninsula toward the central Weddell Sea. Rossby wave train associated with the internal atmospheric variability featuring circumglobal zonal wavenumber 4 pattern induces the development of anomalous surface winds and sea ice drifting, leading to the SIC anomalies directly. The thermodynamical processes associated with the intraseasonal SIC variability include the air temperature, the moisturizing of the lower troposphere, the latent and sensible heating, and the downwelling longwave radiation, which contribute to the variation of the local greenhouse effect over the Weddell Sea, and thus lead to the sea ice variation. The investigation of the intraseasonal SIC variability helps the understanding of sea‐ice‐atmosphere interaction over the Antarctic region. Plain Language Summary: The variation of the Antarctic sea ice can modulate the atmospheric circulation over the Southern Hemisphere and play an important role in the sea‐ice‐atmosphere interaction. The intraseasonal sea ice concentration (SIC) variability over the Antarctic is more evident and with larger extent over the Weddell Sea during austral autumn, featuring a dominant frequency of 5–20 days. The evolution of the intraseasonal SIC variability manifests as SIC anomalies appearing over the northeastern Antarctic Peninsula and then moving eastward to the central Weddell Sea. It is controlled by the propagation of wave train around the Antarctic, which induces surface wind anomalies and sea ice movement. Besides, the air temperature, moisture, the latent and sensible heating, and the doweling longwave radiation can also contribute to the increase or melting of the sea ice through the modulation of the local greenhouse effect. Key Points: The intraseasonal sea ice concentration (SIC) variability over the Weddell Sea manifests an evident frequency of 5–20 days in austral autumnRossby wave train induces anomalous surface winds and sea ice drifting, leading to the intraseasonal SIC anomalies over the Weddell SeaThermodynamical processes including moisture and longwave radiation can modulate local greenhouse effect and intraseasonal SIC anomalies [ABSTRACT FROM AUTHOR]