Coupling a thermodynamically active ice shelf to a regional simulation of the Weddell Sea

Abstract. A thermodynamically interactive ice shelf cavity parameterization is coupled to the Regional Ocean Model System (ROMS) and is applied to the Southern Ocean domain with enhanced resolution in the Weddell Sea. This implementation is tested in order to assess its degree of improvement to the hydrography (and circulation) of the Weddell Sea. Results show that the inclusion of ice shelf cavities in the model is feasible and somewhat realistic (considering the lack of under-ice observations for validation). Ice shelf–ocean interactions are an important process to be considered in order to obtain realistic hydrographic values under the ice shelf. The model framework presented in this work is a promising tool for analyzing the Southern Ocean's response to future climate change scenarios.

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A numerical study of the Southern Ocean including a thermodynamic active ice shelf – Part 1: Weddell Sea

Geoscientific Model Development Discussions ◽

10.5194/gmdd-5-4037-2012 ◽

2012 ◽

Vol 5 (4) ◽

pp. 4037-4069

Author(s):

V. Meccia ◽

I. Wainer ◽

M. Tonelli ◽

E. Curchitser

Keyword(s):

Southern Ocean ◽

Sea Ice ◽

Ocean Circulation ◽

Numerical Study ◽

Weddell Sea ◽

Future Climate Change ◽

Climate Change Scenarios ◽

Ice Shelf ◽

Model Framework ◽

Ice Shelves

Abstract. There is a great amount of uncertainty regarding the understanding of the atmosphere-ocean-cryosphere interactions in the Southern Ocean despite the role that the region plays in our changing climate. With the aim of studying the relative importance of sea-ice and ice shelf processes in the Southern Ocean, a coupled ocean circulation sea-ice/ice shelf cavity model based on the Regional Ocean Model System (ROMS) is used in a periodic circumpolar domain with enhanced resolution in the Weddell Sea. A hierarchy of numerical experiments is performed where first a sea-ice model is used and then an ice shelf thermodynamic parameterization is included in order to evaluate the improvements resulting from each component. Results show that it is necessary to consider the formation and melting of sea-ice in order to adequately reproduce the observed hydrography and circulation. Inclusion of ice shelves cavities in the model only improves results if the ice shelf-ocean thermodynamic fluxes are active. Ice shelves and ocean interactions are an important process to be considered in order to obtain realistic hydrographic values under the ice shelf. The model framework presented in this work is a promising tool for analyzing the Southern Ocean response to future climate change scenarios.

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Quantifying uncertainty in future projections of ice loss from the Filchner-Ronne Ice Shelf System

10.5194/egusphere-egu2020-16045 ◽

2020 ◽

Author(s):

Emily Hill ◽

Sebastian Rosier ◽

Hilmar Gudmundsson ◽

Matthew Collins

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Ice Sheet ◽

Weddell Sea ◽

Future Climate Change ◽

Model Parameters ◽

Climate Change Scenarios ◽

Ice Shelf ◽

Ice Dynamics ◽

Future Projections

Mass loss from the Antarctic Ice Sheet is the main source of uncertainty in projections of future sea-level rise, with important implications for coastal regions worldwide. Enhanced melt beneath ice shelves could destabilise large parts of the ice sheet, and further increase ice loss. Despite advances in our understanding of feedbacks in the ice sheet-ice shelf-ocean system, future projections of ice loss remain poorly constrained in many parts of Antarctica. In particular, there is ongoing debate surrounding the future of the Filchner-Ronne Ice Shelf (FRIS) region. The FRIS has remained relatively unchanged in recent decades, but an increase in air and ocean temperatures in the neighbouring Weddell Sea, could force rapid retreat in the near future. Indeed, previous modelling work has suggested the potential for widespread infiltration of warm water beneath the ice shelf in the second half of the twenty-first century, leading to a drastic increase in basal melting.Here, we use the ice flow model &#218;a alongside the ocean box model PICO (Potsdam Ice-shelf Cavity mOdel) to understand the key physical processes and model variability in future projections of sea level rise from the FRIS region. We investigate uncertain model parameters associated with ice dynamics, surface melting and precipitation, ocean temperature forcing, and parameters relating to the strength of basal melt generated by PICO. We optimise the prior distributions of parameters in PICO using observations and a Bayesian approach, leading to improved posterior distributions for use in the following stages of uncertainty quantification. We then run our forward model through the 21st century for various RCP scenarios and extensive random sampling of uncertain parameters to train an emulator. From this, we present probabilistic projections of potential sea level rise from the FRIS region for different future climate change scenarios, together with a sensitivity analysis to identify the most important parameters that contribute to uncertainty in these projections.

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Modeling the Influence of the Weddell Polynya on the Filchner–Ronne Ice Shelf Cavity

Journal of Climate ◽

10.1175/jcli-d-19-0203.1 ◽

2019 ◽

Vol 32 (16) ◽

pp. 5289-5303 ◽

Cited By ~ 2

Author(s):

Kaitlin A. Naughten ◽

Adrian Jenkins ◽

Paul R. Holland ◽

Ruth I. Mugford ◽

Keith W. Nicholls ◽

...

Keyword(s):

Continental Shelf ◽

Deep Convection ◽

Ocean Model ◽

Shelf Break ◽

Weddell Sea ◽

Ice Shelf ◽

Warm Deep Water ◽

Regional Ocean Model ◽

Ocean Models ◽

Basal Melting

ABSTRACT Open-ocean polynyas in the Weddell Sea of Antarctica are the product of deep convection, which transports Warm Deep Water (WDW) to the surface and melts sea ice or prevents its formation. These polynyas occur only rarely in the observational record but are a near-permanent feature of many climate and ocean simulations. A question not previously considered is the degree to which the Weddell polynya affects the nearby Filchner–Ronne Ice Shelf (FRIS) cavity. Here we assess these effects using regional ocean model simulations of the Weddell Sea and FRIS, where deep convection is imposed with varying area, location, and duration. In these simulations, the idealized Weddell polynyas consistently cause an increase in WDW transport onto the continental shelf as a result of density changes above the shelf break. This leads to saltier, denser source waters for the FRIS cavity, which then experiences stronger circulation and increased ice shelf basal melting. It takes approximately 14 years for melt rates to return to normal after the deep convection ceases. Weddell polynyas similar to those seen in observations have a modest impact on FRIS melt rates, which is within the range of simulated interannual variability. However, polynyas that are larger or closer to the shelf break, such as those seen in many ocean models, trigger a stronger response. These results suggest that ocean models with excessive Weddell Sea convection may not be suitable boundary conditions for regional models of the Antarctic continental shelf and ice shelf cavities.

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Implementation and Validating of the Regional Ocean Model System (ROMS) for the Sunda Strait connecting the Java Sea to the Indian Ocean

10.5194/egusphere-egu21-3457 ◽

2021 ◽

Author(s):

Subekti Mujiasih ◽

Jean-Marie Beckers ◽

Alexander Barth

Keyword(s):

Time Series ◽

Indian Ocean ◽

Vertical Profile ◽

Ocean Model ◽

Model System ◽

Satellite Sst ◽

Regional Ocean Model System ◽

Regional Ocean Model ◽

The Indian Ocean ◽

Java Sea

Regional Ocean Model System (ROMS) has been simulated for the Sunda Strait, the Java Sea, and the Indian Ocean. The simulation was undertaken for thirteen months of data period (August 2013 &#8211; August 2014). However, we only used four months period for validation, namely September &#8211; December 2013. The input data involved the HYbrid Coordinate Ocean Model (HYCOM) ocean model output by considering atmospheric forcing from the European Centre for Medium-Range Weather Forecasts (ECMWF), without and with tides forcing from TPXO and rivers. The output included vertical profile temperature and salinity, sea surface temperature (SST), seas surface height (SSH), zonal (u), and meridional (v) velocity. We compared the model SST to satellite SST in time series, SSH to tides gauges data in time series, the model u and v component velocity to High Frequency (HF) radial velocity. The vertical profile temperature and salinity were compared to Argo float data and XBT. Besides, we validated the amplitude and phase of the ROMS seas surface height to amplitude and phase of the tides-gauges, including four constituents (M2, S2, K1, O1).

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Application of HY-2 Satellite SST Data in 4D Variational Assimilation Ocean Forecast Model

International Journal of Distributed Systems and Technologies ◽

10.4018/ijdst.2017040102 ◽

2017 ◽

Vol 8 (2) ◽

pp. 15-26

Author(s):

Zhenchang Zhang ◽

Libin Gao ◽

Minquan Guo ◽

Riqing Chen

Keyword(s):

Time Window ◽

Forecast Model ◽

Ocean Model ◽

Satellite Sst ◽

Regional Ocean Model System ◽

Model Research ◽

Numerical Ocean Model ◽

Regional Ocean Model ◽

Taiwan Straits ◽

Marine Environmental

The 4D variational (4DVAR) assimilation numerical ocean model research is proposed. This model for Taiwan Straits (TWS) is based on Regional Ocean Model System (ROMS). The background of the 4DVAR method is introduced and the development process of assimilation system is presented. In the present research, the model assimilated with Sea Surface Temperature (SST) data of HY-2 satellite (Qi, 2012; Xu, 2013) which is the first marine environmental monitoring satellite of China. In this paper, the model processes from Feb. 1 to Feb. 7, 2014 with one-day assimilation time window and root mean square error (RMSE) reduces averagely by 14.7%.

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Tidal influences on a future evolution of the Filchner–Ronne Ice Shelf cavity in the Weddell Sea, Antarctica

The Cryosphere ◽

10.5194/tc-12-453-2018 ◽

2018 ◽

Vol 12 (2) ◽

pp. 453-476 ◽

Cited By ~ 18

Author(s):

Rachael D. Mueller ◽

Tore Hattermann ◽

Susan L. Howard ◽

Laurie Padman

Keyword(s):

Ocean Circulation ◽

Three Dimensional ◽

Ocean Model ◽

Tidal Currents ◽

Weddell Sea ◽

Ice Shelf ◽

Ice Streams ◽

Future Evolution ◽

History Of ◽

Basal Melting

Abstract. Recent modeling studies of ocean circulation in the southern Weddell Sea, Antarctica, project an increase over this century of ocean heat into the cavity beneath Filchner–Ronne Ice Shelf (FRIS). This increase in ocean heat would lead to more basal melting and a modification of the FRIS ice draft. The corresponding change in cavity shape will affect advective pathways and the spatial distribution of tidal currents, which play important roles in basal melting under FRIS. These feedbacks between heat flux, basal melting, and tides will affect the evolution of FRIS under the influence of a changing climate. We explore these feedbacks with a three-dimensional ocean model of the southern Weddell Sea that is forced by thermodynamic exchange beneath the ice shelf and tides along the open boundaries. Our results show regionally dependent feedbacks that, in some areas, substantially modify the melt rates near the grounding lines of buttressed ice streams that flow into FRIS. These feedbacks are introduced by variations in meltwater production as well as the circulation of this meltwater within the FRIS cavity; they are influenced locally by sensitivity of tidal currents to water column thickness (wct) and non-locally by changes in circulation pathways that transport an integrated history of mixing and meltwater entrainment along flow paths. Our results highlight the importance of including explicit tidal forcing in models of future mass loss from FRIS and from the adjacent grounded ice sheet as individual ice-stream grounding zones experience different responses to warming of the ocean inflow.

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Assimilation of Middepth Velocities from Argo Floats in the Western South China Sea

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-18-0233.1 ◽

2020 ◽

Vol 37 (1) ◽

pp. 141-157

Author(s):

Pinqiang Wang ◽

Weimin Zhang ◽

Huizan Wang ◽

Haijin Dai ◽

Xiaohui Wang

Keyword(s):

Data Assimilation ◽

South China Sea ◽

South China ◽

Ocean Model ◽

Trajectory Data ◽

Argo Float ◽

Argo Floats ◽

China Sea ◽

Regional Ocean Model System ◽

Regional Ocean Model

AbstractPrevious studies are mainly limited to temperature and salinity (T/S) profiling data assimilation, while data assimilation based on Argo float trajectory information has received less research focus. In this study, a new method was proposed to assimilate Argo trajectory data: the middepth (indicates the parking depth of Argo floats in this study, ~1200 m) velocities are estimated from Argo trajectories and subsequently assimilated into the Regional Ocean Model System (ROMS) using four-dimensional variational data assimilation (4DVAR) method. This method can avoid a complicated float trajectory model in direct position assimilation. The 2-month assimilation experiments in South China Sea (SCS) showed that this proposed method can effectively assimilate Argo trajectory information into the model and improve middepth velocity field by adjusting the unbalanced component in the velocity increments. The assimilation of the Argo trajectory-derived middepth velocity with other observations (satellite observations and T/S profiling data) together yielded the best performance, and the velocity fields at the float parking depth are more consistent with the Argo float trajectories. In addition, this method will not decrease the assimilation performance of other observations [i.e., sea level anomaly (SLA), sea surface temperature (SST), and T/S profiles], which is indicative of compatibility with other observations in the 4DVAR assimilation system.

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Monsoon-Induced Surge during High Tides at the Southeast Coast of Vietnam: A Numerical Modeling Study

Geosciences ◽

10.3390/geosciences9020072 ◽

2019 ◽

Vol 9 (2) ◽

pp. 72 ◽

Cited By ~ 1

Author(s):

Nguyen Thuy ◽

Tran Tien ◽

Cecilie Wettre ◽

Lars Hole

Keyword(s):

Spring Tide ◽

Ocean Model ◽

Clear Trend ◽

Astronomical Tide ◽

Southeast Coast ◽

Regional Ocean Model System ◽

Operational Forecasts ◽

Regional Ocean Model ◽

Coast Of Vietnam ◽

Total Water Level

In this study, monsoon-induced surge during high tides at the Southeast coast of Vietnam was analyzed based on the observed tide data at the Vung Tau station in the period between 1997—2016. Specifically, the surge was determined by removing the astronomical tide from the observed total water level. The two-dimensional Regional Ocean Model System (ROMS 2D) was applied to simulate the surge induced by monsoons during spring tide. The surge observations showed that the change of peak surge did not follow a clear trend, of either an increase or decrease, over time. A peak surge of over 40 cm appeared mainly in October and November, although the peak of the astronomical tide was higher in December. ROMS 2D was validated with the observational data, and the model could sufficiently reproduce the wind-induced surge during high tides. This study therefor ere commends for ROMS 2D to be used in operational forecasts in this area.

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Circulation beneath the Filchner Ice Shelf, Antarctica, and its sensitivity to changes in the oceanic environment: a case-study

Annals of Glaciology ◽

10.3189/1998aog27-1-99-104 ◽

1998 ◽

Vol 27 ◽

pp. 99-104 ◽

Cited By ~ 18

Author(s):

K. Grosfeld ◽

R. Gerdes

Keyword(s):

Sea Ice ◽

Mass Loss ◽

Ocean Circulation ◽

Large Scale ◽

Ocean Model ◽

Current Situation ◽

Weddell Sea ◽

Ice Formation ◽

Shelf Area ◽

Ice Shelf

We investigate the sensitivity of the ocean circulation in the Filchner Trough to changes in the large-scale oceanic environment and its impact on the mass balance of the Filchner Ice Shelf, Antarctica. Three experiments with a three-dimensional ocean model describe (i) the current situation, (ii) a scenario with increased ocean temperatures, and (iii) a scenario with reduced sea-ice formation rates on the adjacent continental shelf. in the final discussion brief results of a combined scenario with increased ocean temperatures and reduced sea-ice formation are presented. The changes from the current situation affect the circulation in the Filchner Trough, and melting and freezing processes beneath the ice shelf. The latter affect the amount and properties of Ice Shelf Water (ISW), a component of Antarctic Bottom Water. Net basal melt rates provide an overall measure for the changes: while the control run yields 0.35 m a−1 net melting averaged over the Filchner Ice Shelf area, the warming scenario results in a more than twofold increase in ice-shelf mass loss. Reduced production of High Salinity ShelfWater due to smaller sea-ice formation rates in the second scenario leads, on the other hand, to a decrease in basal mass loss, because the deep cavity is less well ventilated than in the control run. ISW is cooled and the ice shelf is stabilized under this scenario, which is arguably the more likely development in the southern Weddell Sea.

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Tidal effects on ichthyoplankton aggregation and dispersion in the Southern Gulf of Mexico

Brazilian Journal of Oceanography ◽

10.1590/s1679-87592013000400004 ◽

2013 ◽

Vol 61 (4) ◽

pp. 231-241 ◽

Cited By ~ 1

Author(s):

María Adela Monreal Gómez ◽

David Alberto Salas de León ◽

Cesar Flores Coto ◽

Fernando Flores Hernández ◽

David Salas Monreal ◽

...

Keyword(s):

Gulf Of Mexico ◽

Single Point ◽

Internal Tide ◽

Ocean Model ◽

Hydraulic Control ◽

Barotropic Tide ◽

Regional Ocean Model System ◽

Southern Gulf Of Mexico ◽

Regional Ocean Model

The role of vertical barotropic and baroclinic tidal forcing in the aggregation and dispersion of ichthyoplankton in the Southern Gulf of Mexico was analyzed in this study. Samplings of ichthyoplankton and the determination of hydrographic parameters were performed during September 1992 at a single point of 180 m depth, near the shelf break (19º32'N - 92º38.5'W). A 24 h CTD yo-yoing casting and biological samples were taken every 2 h and these measurements were combined with water velocity and density simulations from the Regional Ocean Model System (ROMS). One thermocline and two haloclines were depicted. The Froude number increased with a 2 h lag with respect to the maximal barotropic tide, suggesting the existence of a baroclinic tide. Aggregation and dispersion of the ichthyoplankton showed vertical oscillations in the abundance and the numbers of taxa and larvae with a 5 h lag with respect to the maximal barotropic tide and were in phase with the thermocline oscillation. The vertical oscillation was attributed to a hydraulic control forced by the internal tide.

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