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Sensitivity Of The Relationship Between Antarctic Ice Shelves And Iron Supply To Projected Changes In The Atmospheric Forcing, Michael S. Dinniman, Pierre St-Laurent, Kevin R. Arrigo, Eileen E. Hofmann, Gert L. Van Dijken
Sensitivity Of The Relationship Between Antarctic Ice Shelves And Iron Supply To Projected Changes In The Atmospheric Forcing, Michael S. Dinniman, Pierre St-Laurent, Kevin R. Arrigo, Eileen E. Hofmann, Gert L. Van Dijken
CCPO Publications
Upward advection or mixing of iron-rich deep waters due to circulation changes driven by the rate of basal ice shelf melt was shown to be a primary control on chlorophyll a production in coastal polynyas over the Antarctic continental shelf. Here, the effects of atmospheric changes projected in 2100 on this relationship were examined with a 5-km resolution ocean/sea ice/ice shelf model of the Southern Ocean with different simulated dissolved iron sources and idealized biological uptake. The atmospheric changes are added as idealized increments to the forcing. Inclusion of a poleward shift and strengthening of the winds, increased precipitation, and …
The Response Of Sea Ice And High-Salinity Shelf Water In The Ross Ice Shelf Polynya To Cyclonic Atmosphere Circulations, Xiaoqiao Wang, Zhaoru Zhang, Michael S. Dinniman, Petteri Uotila, Xichen Li, Meng Zhou
The Response Of Sea Ice And High-Salinity Shelf Water In The Ross Ice Shelf Polynya To Cyclonic Atmosphere Circulations, Xiaoqiao Wang, Zhaoru Zhang, Michael S. Dinniman, Petteri Uotila, Xichen Li, Meng Zhou
CCPO Publications
Coastal polynyas in the Ross Sea are important source regions of high-salinity shelf water (HSSW) – the precursor of Antarctic Bottom Water that supplies the lower limb of the thermohaline circulation. Here, the response of sea ice production and HSSW formation to synoptic-scale and mesoscale cyclones was investigated for the Ross Ice Shelf Polynya (RISP) using a coupled ocean–sea ice–ice shelf model targeted on the Ross Sea. When synoptic-scale cyclones prevailed over RISP, sea ice production (SIP) increased rapidly by 20 %–30 % over the entire RISP. During the passage of mesoscale cyclones, SIP increased by about 2 times over …
Seasonal Variations In Circumpolar Deep Water Intrusions Into The Ross Sea Continental Shelf, Yufei Wang, Meng Zhou, Zhaoru Zhang, Michael S. Dinniman
Seasonal Variations In Circumpolar Deep Water Intrusions Into The Ross Sea Continental Shelf, Yufei Wang, Meng Zhou, Zhaoru Zhang, Michael S. Dinniman
CCPO Publications
Intrusions of the warm and nutrient-rich Circumpolar Deep Water (CDW) across the Ross Sea shelf break play an important role in providing heat for ice shelf basal melting and setting the physical environment for biochemical processes. Several mechanisms driving CDW intrusions into the Ross Sea were proposed such as mesoscale eddies, tidal rectification, and interactions between Antarctic Slope Current (ASC) and topographic features. The seasonal variations in the poleward transport of CDW are investigated using ERA-Interim wind data and a Ross Sea circulation model based on the Regional Ocean Modeling System (ROMS) between September 1999 and September 2014. The analyses …
Dataset: A Numerical Simulation Of The Ocean, Sea Ice And Ice Shelves In The Amundsen Sea (Antarctica) Over The Period 2006-2022 And Its Associated Code And Input Files, Pierre St-Laurent
Dataset: A Numerical Simulation Of The Ocean, Sea Ice And Ice Shelves In The Amundsen Sea (Antarctica) Over The Period 2006-2022 And Its Associated Code And Input Files, Pierre St-Laurent
Data
A three-dimensional numerical model of the Amundsen Sea (Antarctica) was used to simulate the period Jan.2006-Mar.2022 under consistent atmospheric/oceanic forcings, bathymetry/ice shelf topography, and model equations/parameters. The model is an implementation of the Regional Ocean Modeling System (ROMS, https://www.myroms.org/) with extensions for sea ice (Budgell 2005) and ice shelves (Dinniman et al. 2011). It simulates the ocean hydrography and circulation, sea ice thermodynamics and dynamics, and the basal melt of the ice shelves, with a uniform horizontal mesh of 1.5km and 20 topography-following vertical levels. Forcings include the ERA5 reanalysis (3-hourly), 10 tidal constituents from CATS 2008, and ocean/sea ice …
On The Relative Importance Of Offshelf/Onshelf Drivers Of Variability In Mcdw Inventory On The Amundsen Shelf, Antarctica, Pierre St-Laurent, S. E. Stammerjohn, T. Maksym, R. M. Sherrell
On The Relative Importance Of Offshelf/Onshelf Drivers Of Variability In Mcdw Inventory On The Amundsen Shelf, Antarctica, Pierre St-Laurent, S. E. Stammerjohn, T. Maksym, R. M. Sherrell
Presentations
Ice shelves in the Amundsen Sea (west Antarctica) are melting rapidly and may raise global sea levels substantially over the coming century through reduced buttressing. The high basal melt rates are associated with the presence of warm modified Circumpolar Deep Water (mCDW) that intrudes across the continental shelf and melts the floating portion of the ice sheet from its base near the grounding zone. How much mCDW is present on the continental shelf (its volume inventory) is thus thought to be a key proxy for the year-to-year variability in ice shelf melt rates. Over the past decade, the literature has …
Seasonal Dynamics Of Dissolved Iron On The Antarctic Continental Shelf: Late-Fall Observations From The Terra Nova Bay And Ross Ice Shelf Polynyas, P. N. Sedwick, B. M. Sohst, C. O'Hara, S. E. Stammerjohn, B. Loose, M. S. Dinniman, N. J. Buck, J. A. Resing, S. F. Ackley
Seasonal Dynamics Of Dissolved Iron On The Antarctic Continental Shelf: Late-Fall Observations From The Terra Nova Bay And Ross Ice Shelf Polynyas, P. N. Sedwick, B. M. Sohst, C. O'Hara, S. E. Stammerjohn, B. Loose, M. S. Dinniman, N. J. Buck, J. A. Resing, S. F. Ackley
OES Faculty Publications
Over the Ross Sea shelf, annual primary production is limited by dissolved iron (DFe) supply. Here, a major source of DFe to surface waters is thought to be vertical resupply from the benthos, which is assumed most prevalent during winter months when katabatic winds drive sea ice formation and convective overturn in coastal polynyas, although the impact of these processes on water-column DFe distributions has not been previously documented. We collected hydrographic data and water-column samples for trace metals analysis in the Terra Nova Bay and Ross Ice Shelf polynyas during April-May 2017 (late austral fall). In the Terra Nova …
Constraining An Ocean Model Under Getz Ice Shelf, Antarctica, Using A Gravity‐Derived Bathymetry, Romain Millan, Pierre St-Laurent, Eric Rignot, Mathieu Morlighem, Jeremie Mouginot, Bernd Scheuchl
Constraining An Ocean Model Under Getz Ice Shelf, Antarctica, Using A Gravity‐Derived Bathymetry, Romain Millan, Pierre St-Laurent, Eric Rignot, Mathieu Morlighem, Jeremie Mouginot, Bernd Scheuchl
CCPO Publications
Getz Ice Shelf, the largest producer of ice shelf meltwater in Antarctica, buttresses glaciers that hold enough ice to raise sea level by 22 cm. We present a new bathymetry of its sub‐ice shelf cavity using a three‐dimensional inversion of airborne gravity data constrained by multibeam bathymetry at sea and a reconstruction of the bedrock from mass conservation on land. The new bathymetry is deeper than previously estimated with differences exceeding 500 m in a number of regions. When incorporated into an ocean model, it yields a better description of the spatial distribution of ice shelf melt, specifically along glacier …
Analysis Of Iron Sources In Antarctic Continental Shelf Waters, Michael S. Dinniman, Pierre St-Laurent, Kevin R. Arrigo, Eileen E. Hofmann, Gert L. Van Dijken
Analysis Of Iron Sources In Antarctic Continental Shelf Waters, Michael S. Dinniman, Pierre St-Laurent, Kevin R. Arrigo, Eileen E. Hofmann, Gert L. Van Dijken
CCPO Publications
Previous studies showed that satellite‐derived estimates of chlorophyll a in coastal polynyas over the Antarctic continental shelf are correlated with the basal melt rate of adjacent ice shelves. A 5‐km resolution ocean/sea ice/ice shelf model of the Southern Ocean is used to examine mechanisms that supply the limiting micronutrient iron to Antarctic continental shelf surface waters. Four sources of dissolved iron are simulated with independent tracers, assumptions about the source iron concentration for each tracer, and an idealized summer biological uptake. Iron from ice shelf melt provides about 6% of the total dissolved iron in surface waters. The contribution from …
Vertical Processes And Resolution Impact Ice Shelf Basal Melting: A Multi-Model Study, David E. Gwyther, Kazuya Kusahara, Xylar S. Asay-Davis, Michael S. Dinniman, Benjamin K. Galton-Fenzi
Vertical Processes And Resolution Impact Ice Shelf Basal Melting: A Multi-Model Study, David E. Gwyther, Kazuya Kusahara, Xylar S. Asay-Davis, Michael S. Dinniman, Benjamin K. Galton-Fenzi
CCPO Publications
Understanding ice shelf–ocean interaction is fundamental to projecting the Antarctic ice sheet response to a warming climate. Numerical ice shelf–ocean models are a powerful tool for simulating this interaction, yet are limited by inherent model weaknesses and scarce observations, leading to parameterisations that are unverified and unvalidated below ice shelves. We explore how different models simulate ice shelf–ocean interaction using the 2nd Ice Shelf–Ocean Model Intercomparison Project (ISOMIP+) framework. Vertical discretisation and resolution of the ocean model are shown to have a significant effect on ice shelf basal melt rate, through differences in the distribution of meltwater fluxes and the …
Associated Dataset: Modeling The Seasonal Cycle Of Iron And Carbon Fluxes In The Amundsen Sea Polynya, Antarctica, Pierre St-Laurent
Associated Dataset: Modeling The Seasonal Cycle Of Iron And Carbon Fluxes In The Amundsen Sea Polynya, Antarctica, Pierre St-Laurent
Data
This dataset features the results from the numerical simulation described in the associated publication (St-Laurent et al.). The simulation results are in the standard, self-documented NetCDF format (extension .nc); see https://www.unidata.ucar.edu/software/netcdf/ for more information. Files in this format can be manipulated and displayed by a wide range of freely available software. The results from the simulation are divided into monthly files (ocean_avg_0001.nc to ocean_avg_0098.nc). Each file holds 30 days worth of time-averaged daily model fields, from January 2006 to December 2013. The dataset also includes the forcings used in the model calculation (in the same format as above). Detailed information …
Modeling Ocean Eddies On Antarctica's Cold Water Continental Shelves And Their Effects On Ice Shelf Basal Melting, Stefanie L. Mack, Michael S. Dinniman, John M. Klinck, Dennis J. Mcgillicuddy, Laurence Padman
Modeling Ocean Eddies On Antarctica's Cold Water Continental Shelves And Their Effects On Ice Shelf Basal Melting, Stefanie L. Mack, Michael S. Dinniman, John M. Klinck, Dennis J. Mcgillicuddy, Laurence Padman
CCPO Publications
Changes in the rate of ocean‐driven basal melting of Antarctica's ice shelves can alter the rate at which the grounded ice sheet loses mass and contributes to sea level change. Melt rates depend on the inflow of ocean heat, which occurs through steady circulation and eddy fluxes. Previous studies have demonstrated the importance of eddy fluxes for ice shelves affected by relatively warm intrusions of Circumpolar Deep Water. However, ice shelves on cold water continental shelves primarily melt from dense shelf water near the grounding line and from light surface water at the ice shelf front. Eddy effects on basal …
Modeling The Seasonal Cycle Of Iron And Carbon Fluxes In The Amundsen Sea Polynya, Antarctica, P. St-Laurent, P. L. Yager, R. M. Sherrell, H. Oliver, M. S. Dinniman, S. E. Stammerjohn
Modeling The Seasonal Cycle Of Iron And Carbon Fluxes In The Amundsen Sea Polynya, Antarctica, P. St-Laurent, P. L. Yager, R. M. Sherrell, H. Oliver, M. S. Dinniman, S. E. Stammerjohn
CCPO Publications
The Amundsen Sea Polynya (ASP) is distinguished by having the highest net primary production per unit area in the coastal Antarctic. Recent studies have related this high productivity to the presence of fast-melting ice shelves, but the mechanisms involved are not well understood. In this study we describe the first numerical model of the ASP to represent explicitly the ocean-ice interactions, nitrogen and iron cycles, and the coastal circulation at high resolution. The study focuses on the seasonal cycle of iron and carbon, and the results are broadly consistent with field observations collected during the summer of 2010–2011. The simulated …
Modeling Ice Shelf/Ocean Interaction In Antarctica: A Review, Michael S. Dinniman, Xylar S. Asay-Davis, Benjamin K. Galton-Fenzi, Paul R. Holland, Adrian Jenkins, Ralph Timmerman
Modeling Ice Shelf/Ocean Interaction In Antarctica: A Review, Michael S. Dinniman, Xylar S. Asay-Davis, Benjamin K. Galton-Fenzi, Paul R. Holland, Adrian Jenkins, Ralph Timmerman
CCPO Publications
The most rapid loss of ice from the Antarctic Ice Sheet is observed where ice streams flow into the ocean and begin to float, forming the great Antarctic ice shelves that surround much of the continent. Because these ice shelves are floating, their thinning does not greatly influence sea level. However, they also buttress the ice streams draining the ice sheet, and so ice shelf changes do significantly influence sea level by altering the discharge of grounded ice. Currently, the most significant loss of mass from the ice shelves is from melting at the base (although iceberg calving is a …
Modelling The Response Of Ice Shelf Basal Melting To Different Ocean Cavity Environmental Regimes, David E. Gwyther, Eva A. Cougnon, Benjamin K. Galton-Fenzi, Jason L. Roberts, John R. Hunter, Michael S. Dinniman
Modelling The Response Of Ice Shelf Basal Melting To Different Ocean Cavity Environmental Regimes, David E. Gwyther, Eva A. Cougnon, Benjamin K. Galton-Fenzi, Jason L. Roberts, John R. Hunter, Michael S. Dinniman
CCPO Publications
We present simulation results from a version of the Regional Ocean Modeling System modified for ice shelf/ocean interaction, including the parameterisation of basal melting by molecular diffusion alone. Simulations investigate the differences in melting for an idealised ice shelf experiencing a range of cold to hot ocean cavity conditions. Both the pattern of melt and the location of maximum melt shift due to changes in the buoyancy-driven circulation, in a different way to previous studies. Tidal forcing increases both the circulation strength and melting, with the strongest impact on the cold cavity case. Our results highlight the importance of including …
Impact Of Local Winter Cooling On The Melt Of Pine Island Glacier, Antarctica, P. St-Laurent, J. M. Klinck, M. S. Dinniman
Impact Of Local Winter Cooling On The Melt Of Pine Island Glacier, Antarctica, P. St-Laurent, J. M. Klinck, M. S. Dinniman
CCPO Publications
The rapid thinning of the ice shelves in the Amundsen Sea is generally attributed to basal melt driven by warm water originating from the continental slope. We examine the hypothesis that processes taking place on the continental shelf contribute significantly to the interannual variability of the ocean heat content and ice shelf melt rates. A numerical model is used to simulate the circulation of ocean heat and the melt of the ice shelves over the period 2006–2013. The fine model grid (grid spacing 1.5 km) explicitly resolves the coastal polynyas and mesoscale processes. The ocean heat content of the eastern …
The Effect Of Atmospheric Forcing Resolution On Delivery Of Ocean Heat To The Antarctic Floating Ice Shelves, Michael S. Dinniman, John M. Klinck, Le-Sheng Bai, David H. Bromwich, Keith M. Hines, David M. Holland
The Effect Of Atmospheric Forcing Resolution On Delivery Of Ocean Heat To The Antarctic Floating Ice Shelves, Michael S. Dinniman, John M. Klinck, Le-Sheng Bai, David H. Bromwich, Keith M. Hines, David M. Holland
CCPO Publications
Oceanic melting at the base of the floating Antarctic ice shelves is now thought to be a more significant cause of mass loss for the Antarctic ice sheet than iceberg calving. In this study, a 10-km horizontal-resolution circum-Antarctic ocean–sea ice–ice shelf model [based on the Regional Ocean Modeling System (ROMS)] is used to study the delivery of ocean heat to the base of the ice shelves. The atmospheric forcing comes from the ERA-Interim reanalysis (;80-km resolution) and from simulations using the polar-optimized Weather Re- search and Forecasting Model (30-km resolution), where the upper atmosphere was relaxed to the ERA- Interim …
Satellite-Based Estimates Of Antarctic Surface Meltwater Fluxes, Luke D. Trusel, Karen E. Frey, Sarah B. Das, Peter Kuipers Munneke, Michiel R. Van Den Broeke
Satellite-Based Estimates Of Antarctic Surface Meltwater Fluxes, Luke D. Trusel, Karen E. Frey, Sarah B. Das, Peter Kuipers Munneke, Michiel R. Van Den Broeke
Geography
This study generates novel satellite-derived estimates of Antarctic-wide annual (1999-2009) surface meltwater production using an empirical relationship between radar backscatter from the QuikSCAT (QSCAT) satellite and melt calculated from in situ energy balance observations. The resulting QSCAT-derived melt fluxes significantly agree with output from the regional climate model RACMO2.1 and with independent ground-based observations. The high-resolution (4.45 km) QSCAT-based melt fluxes uniquely detect interannually persistent and intense melt (>400 mm water equivalent (w.e.) year-1) on interior Larsen C Ice Shelf that is not simulated by RACMO2.1. This supports a growing understanding of the importance of a föhn effect in …