10:15 〜 10:30
[MIS10-06] ウェッデル海域の領域モデル開発
キーワード：南大洋、海洋モデル、棚氷
The Filchner Ronne Ice Shelf (FRIS), the largest volume in Antarctica, is considered to be protected from the inflow of warm Circumpolar Deep Water (CDW) surrounding the Antarctic continent by cold and saline water. If warm water flows into the FRIS cavity and accelerates the ice shelf melting, it will have a significant impact on the sea level and surrounding hydrography. A previous large-scale modeling study suggests that the inflow of warm water into the lower ice shelf during this century could increase the amount of basal melt by a factor of 20. However, due to a lack of observational data and the fact that most modeling studies of the Weddell Sea use global models, the detailed mechanism and under what conditions this would occur remains unclear.
Here, we develop a regional model of the Weddell Sea using the Massachusetts Institute of Technology general circulation model (MITgcm) for 1992-2020. Horizontal grid spacing is 3-4km and the vertical discretization comprises 50 levels with varying thicknesses. We are able to reproduce the thickness and properties of Ice Shelf Water (ISW), High Salinity Shelf Water (HSSW), and modified Warm Deep Water (mWDW) close to observations at the FRIS front, with significant improvement for ice shelf front hydrography and circulation compared to previous studies. For example, ISW and HSSW can be found at the ice shelf front and their properties are colder and fresher by -0.05℃ and 0.05 psu, respectively.
Ronne-HSSW produced by sea ice production in the offshore Ronne area flows into the Ronne ice shelf (RIS) cavity. When it reaches close to the grounding line, it melts the ice shelf and forms ISW (the mixture of HSSW and glacial meltwater). The RIS and the Filchner Ice Shelf (FIS) are connected at the deepest part, and the ISW flows out through the Filchner Ice Shelf towards the continental shelf. The residence time scale of the circulation at the ice shelf cavity was roughly 1~2 years, consistent with the observation estimates. The mWDW has two pathways into the ice shelf cavities. One flows along the eastern side of the Filchner Trough and the other flows along the eastern side of the Central Trough to the FRIS front.
Future projection experiments will also be carried out to investigate the possibility of regime shifts inherent in the Weddell Sea Filchner-Ronne ice shelf cavity and ocean circulation.
Here, we develop a regional model of the Weddell Sea using the Massachusetts Institute of Technology general circulation model (MITgcm) for 1992-2020. Horizontal grid spacing is 3-4km and the vertical discretization comprises 50 levels with varying thicknesses. We are able to reproduce the thickness and properties of Ice Shelf Water (ISW), High Salinity Shelf Water (HSSW), and modified Warm Deep Water (mWDW) close to observations at the FRIS front, with significant improvement for ice shelf front hydrography and circulation compared to previous studies. For example, ISW and HSSW can be found at the ice shelf front and their properties are colder and fresher by -0.05℃ and 0.05 psu, respectively.
Ronne-HSSW produced by sea ice production in the offshore Ronne area flows into the Ronne ice shelf (RIS) cavity. When it reaches close to the grounding line, it melts the ice shelf and forms ISW (the mixture of HSSW and glacial meltwater). The RIS and the Filchner Ice Shelf (FIS) are connected at the deepest part, and the ISW flows out through the Filchner Ice Shelf towards the continental shelf. The residence time scale of the circulation at the ice shelf cavity was roughly 1~2 years, consistent with the observation estimates. The mWDW has two pathways into the ice shelf cavities. One flows along the eastern side of the Filchner Trough and the other flows along the eastern side of the Central Trough to the FRIS front.
Future projection experiments will also be carried out to investigate the possibility of regime shifts inherent in the Weddell Sea Filchner-Ronne ice shelf cavity and ocean circulation.