Impact of parameterisations of the future Antarctic Ice Shelf meltwater for Dense Shelf Water formation in ACCESS-OM2
Fabio Boeira Dias
The abyssal branch of the global meridional overturning circulation (MOC) accounts for over 30% of the ocean’s volume and plays a vital role in Earth’s climate regulation. This abyssal circulation originates at the Antarctic margins, wherecold, salty, and dense waters form due to intense sea-ice production in coastal polynyas. This Dense Shelf Water (DSW) then sinks to the ocean floor, spreading into the abyss. Recent studies have shown that this branch is sensitive to meltwater from Antarctic ice shelf melting—a process that hs accelerated over recent decades. However, many climate models prescribe this meltwater at the surface, limiting insight into its impact on DSW formation.
Using the global ocean–sea ice model ACCESS-OM2-01, we explore how different meltwater prescriptions affect abyssal circulation. We compare meltwater input at the surface versus at the depth of the ice shelf cavities; the inclusion of ocean heat loss from ice melting, and a brine rejection parameterisation that mitigates unrealistic convection triggered by supercooled ice shelf water. Ongoing experiments aim to provide insight into the sensitivity of abyssal circulation to these different meltwater representations, including DSW formation, shelf circulation and abyssal MOC, improving projections of future ocean circulation changes.
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