The Antarctic Slope Current (ASC), coupled with the Antarctic Slope Front (ASF), encircles Antarctica and is a roughly longshore flow. Yet, the instabilities of the ASC/ASF can induce cross-slope exchanges. The ASC/ASF instabilities excited by external forcing have been studied extensively in previous literature. However, the mechanisms responsible for the intrinsic instabilities are still not clear. Based on an idealized eddy-resolving model, this study focuses on the intrinsic instabilities of the ASC/ASF. The ASC/ASF is classified into three types: Fresh Shelf, Warm Shelf, and Dense Shelf. Accordingly, three high-resolution process-oriented numerical experiments are conducted to reveal the characteristics, the dynamic mechanisms, and the influences of the intrinsic instabilities. In the Fresh Shelf case, the intrinsic instabilities are characterized by a submesoscale vortex train over the middle-lower slope, associated with the Topographic Rossby waves. In the Warm Shelf case, large mesoscale eddies are generated over the slope upstream and dominate the deep ocean downstream. In the Dense Shelf case, a mesoscale vortex train is present over the lower slope, and abundant filaments and jets can flow across the shelf break. The baroclinic instability greatly contributes to the generation of intrinsic instabilities in the three cases. As a unique feature of the instabilities, coherent eddies have been identified and significantly favor the cross-slope exchanges by the advection of water boluses retaining source water. The eddy-induced transport cannot cross the shelf break in the Fresh Shelf case but effectively results in cross-slope exchanges in the Warm Shelf and Dense Shelf cases.

Antarctic Slope Current,Instabilities