The Ross Gyre is one of three gyres that exists within the Southern Ocean around Antarctica, the others being the Weddell Gyre and Balleny Gyre. The Ross Gyre is located north of the Ross Sea, and rotates clockwise. The gyre is formed by interactions between the Antarctic Circumpolar Current and the Antarctic Continental Shelf. The Ross Gyre is bounded by the Polar Front of the Antarctic Circumpolar Current to the north, the Antarctic Slope Current to the south, the Balleny Gyre to the west, and a variable boundary to the east from semiannual changes in sea surface height (SSH) in the Amundsen Sea. Circulation in the Ross Gyre has been estimated to be 20 ± 5 Sverdrup (Sv) and plays a large role in heat exchange in this region.

The salinity, nutrient, and carbon patterns in the gyre are related to seasonal ice cover and freshwater input.

Antarctic toothfish, orcas, Adélie penguins, Antarctic krill, Salpidae, Slender-billed prion and many other seabirds spend part of their lives in the Ross Gyre.

Climate change predictions anticipate a strengthening of the gyre's circulation which would increase shelf ice melt and slowdown deep water formation.

The Ross Gyre is a clockwise-rotating water mass that lies north of the Ross Sea. This gyre is bounded to the north by the Polar Front of the Antarctic Circumpolar Current (ACC) and Pacific-Antarctic Ridge bathymetry, and to the south by the Antarctic Slope Current (ASC) and the Antarctic continental shelf. The gyre is located between 160°E and 140°W with a variable eastern boundary associated with the eastern extension of the Pacific-Antarctic Ridge. The Ross Gyre is bounded to the west by the presence of another gyre, the Balleny Gyre, associated with the Balleny fracture zone. The northeast boundary of the Ross Gyre expands and contracts semiannually due to reduced sea surface height (SSH) north of the gyre following deepening of the Amundsen Sea Low (ASL) to the east. The gyre is largest in area in May and November, and lowest following winter and in summer. The center of the gyre is located between 164°W, 68°S, and 150°W, 63°S, depending on 100/500m or 1500/3000m steric anomaly height maps, respectively.

Physical formation processes for the Ross Gyre remain unclear and difficult to study, but current theories attribute wind forcing and zonal momentum conservation balanced by vorticity gradients and bottom frictional forces to its formation. Prevailing polar westerlies create an eastern flowing ACC that is balanced by the topography of the seafloor that drives this formation. The eastern boundary is closely linked to where the ACC crosses the Pacific-Antarctic Ridge, at the Udintsev fracture zone, with a southward deflection to conserve vorticity. Near the shelf, the gyre circulates westward following the westward flow of the Antarctic Slope Current. Other theories attributing blocked geostrophic flows on a western landmass to Southern Ocean gyre formation have been challenged, as the Ross Gyre forms without any geostrophic contours being blocked. However, modeling simulations underline the importance of the northern ridge system in strengthening subpolar gyre circulation and shaping the stratification of the region.

The Ross Gyre plays an important role in exchanging polar water masses and heat in Antarctica, connecting the ACC to the Antarctic shelf. The undefined eastern boundary of the gyre entrains relatively warm Circumpolar Deep Water (CDW) that is transferred to the continental shelf and the Bellingshausen and Amundsen Seas, which can effect sea ice melting rates and shelf ice extent. Eddy formation through gaps in the Pacific-Antarctic Ridge are hypothesized to facilitate this transport between the Antarctic Circumpolar Current and the Ross Gyre. The western limb of the gyre mediates the transfer of cold meltwater and newly formed Antarctic Bottom Water (AABW) originating in the Ross Sea northward. The presence of cold surface waters and warmer intermediate waters forms a double diffusive staircase within the Ross Gyre; this feature limits vertical heat exchange, and allows the development of ice in the gyre's center. It is estimated that the circulation of the Ross Gyre exports 20 ± 5 Sverdrup.

At 500 meters deep, the surface water density in the Ross Gyre is higher than the surface water density measured at the Amundsen Seas, which is located to the east of the Ross gyre, during summer and winter because the Ross Gyre has a higher salinity at the surface than the Amundsen Seas. An explanation for these salinities is the addition of more meltwater in the Amundsen sea coming from the coastal shelf than in the Ross Gyre. Salinity has been recorded to be decreasing in the 40 years in the gyre as a result of the melting of ice shelves and the addition of fresh water. The change in salinity is the same as adding 18 mm of freshwater to the surface of the gyre. The southern area of the Ross Gyre has the strongest changes in salinity recorded. As the Ross Gyre is fairly remote, the biogeochemistry of this region is relatively under sampled. Recently, Argo floats, autonomous drifting and profiling platforms with various biogeochemical sensors including temperature, salinity, and nutrients, have been used to increase sampling effort. Argo floats deployed in the Ross Gyre have also measured temperatures between -1.0 – 2.5 °C ± 1 °C, salinity between 33.8 – 34.6 ± 0.2 PSU, and nitrate concentrations between 26 – 32 ± 1 μmol kg⁻¹.