5:15 PM - 6:45 PM
[MIS10-P14] Integrating an ice-shelf component into a global ocean-sea ice model: Assessing the impact of the recent Antarctic cryosphere changes on the Southern and global oceans
In recent decades, the Antarctic cryosphere has undergone significant changes, prompting a need to understand their implications on the global ocean system. In this study, we integrated an ice-shelf component into a global ocean-sea ice model, COCO, with a horizontal resolution of 0.25°. This resolution enables realistic representations of coastlines and ice shelves around Antarctica, aiming to provide comprehensive insights into how the recent changes in the Antarctic cryosphere influence both the Southern Ocean and the global oceans.
Satellite observations indicate that while Antarctic sea-ice extent had been gradually increasing from the late 1970s until 2015, after the summer of 2016/2017, it has since undergone a rapid decline, with particularly low ice extents sustained throughout the year 2023. Focusing on the Antarctic coastal regions, variability in the sea-ice extent and formation/melting processes are linked to the formation of coastal water masses along Antarctic coastal margins, which in turn have a tight link to variability in basal melting of the Antarctic ice shelves. Here, we utilize the global ocean-sea ice model with an ice-shelf component to thoroughly analyze these interactions, shedding light on the complex dynamics between sea-ice variability, coastal water mass formation, and ice-shelf basal melting, along with their subsequent impact on the global ocean.
After several decades of model spin-up, we conducted historical simulations for the period 1979-2022, employing boundary conditions derived from the ERA5 atmospheric reanalysis dataset. The model reproduces the observed Antarctic sea-ice extent anomalies, bolstering confidence in the model’s representation of the Southern Ocean. Interestingly, the model indicates a significant increase in Antarctic ice-shelf basal melting since 2016, coinciding with the sharp decline in sea-ice extent. This strong anti-correlation between sea-ice extent and basal melting of ice shelves can be attributed to changes in coastal water masses associated with sea-ice variability along the Antarctic coastal margins. Furthermore, the modeled sea-ice production, particularly in coastal polynya regions, also shows a significant decrease since 2016, with a reduction of about 8% by 2022, with respect to the 1981-2010 average. Given that the coastal sea-ice production directly contributes to the dense shelf water formation, a precursor to Antarctic Bottom Water, this substantial decrease potentially indicates a weakening in the global deep overturning circulation. By the time of presentation, we plan to extend our numerical experiments up to 2023 and discuss the recent variability in the Southern Ocean’s cryosphere, ocean changes, and their global impacts.
Satellite observations indicate that while Antarctic sea-ice extent had been gradually increasing from the late 1970s until 2015, after the summer of 2016/2017, it has since undergone a rapid decline, with particularly low ice extents sustained throughout the year 2023. Focusing on the Antarctic coastal regions, variability in the sea-ice extent and formation/melting processes are linked to the formation of coastal water masses along Antarctic coastal margins, which in turn have a tight link to variability in basal melting of the Antarctic ice shelves. Here, we utilize the global ocean-sea ice model with an ice-shelf component to thoroughly analyze these interactions, shedding light on the complex dynamics between sea-ice variability, coastal water mass formation, and ice-shelf basal melting, along with their subsequent impact on the global ocean.
After several decades of model spin-up, we conducted historical simulations for the period 1979-2022, employing boundary conditions derived from the ERA5 atmospheric reanalysis dataset. The model reproduces the observed Antarctic sea-ice extent anomalies, bolstering confidence in the model’s representation of the Southern Ocean. Interestingly, the model indicates a significant increase in Antarctic ice-shelf basal melting since 2016, coinciding with the sharp decline in sea-ice extent. This strong anti-correlation between sea-ice extent and basal melting of ice shelves can be attributed to changes in coastal water masses associated with sea-ice variability along the Antarctic coastal margins. Furthermore, the modeled sea-ice production, particularly in coastal polynya regions, also shows a significant decrease since 2016, with a reduction of about 8% by 2022, with respect to the 1981-2010 average. Given that the coastal sea-ice production directly contributes to the dense shelf water formation, a precursor to Antarctic Bottom Water, this substantial decrease potentially indicates a weakening in the global deep overturning circulation. By the time of presentation, we plan to extend our numerical experiments up to 2023 and discuss the recent variability in the Southern Ocean’s cryosphere, ocean changes, and their global impacts.