Modeling the effects of frazil ice crystals on the dynamics and thermodynamics of Ice Shelf Water plumes

1995 ◽  
Vol 100 (C4) ◽  
pp. 6967 ◽  
Author(s):  
Adrian Jenkins ◽  
Andreas Bombosch
Keyword(s):  
Ice Crystals ◽  
Shelf Water ◽  
Ice Shelf ◽  
Frazil Ice ◽  
Ice Shelf Water

scholarly journals Vertical Modification on Depth-Integrated Ice Shelf Water Plume Modeling Based on an Equilibrium Vertical Profile of Suspended Frazil Ice Concentration

2017 ◽  
Vol 47 (11) ◽  
pp. 2773-2792 ◽  
Author(s):  
Chen Cheng ◽  
Zhaomin Wang ◽  
Chengyan Liu ◽  
Ruibin Xia
Keyword(s):  
Freezing Point ◽  
Nonlinear Effects ◽  
Freezing Temperature ◽  
Shelf Water ◽  
Ice Shelf ◽  
Frazil Ice ◽  
Ice Concentration ◽  
Plume Modeling ◽  
Ice Shelf Water ◽  
Western Side

AbstractThe ice shelf water (ISW) plume is a prevalent phenomenon at the base of an ice shelf or sea ice adjacent to the ice shelf front. Such plumes may become supercooled and deposit marine ice when they rise. In the existing frazil ice–laden ISW plume models, it is generally assumed that supercooling and frazil ice growth can be adequately treated by using depth-averaged freezing temperature and vertically uniform frazil ice concentration within a plume. In reality, however, the temperature deficit and frazil ice concentration both increase toward the top of the plume. Hence, frazil crystals typically experience a greater deficit than that suggested by the plume’s temperature subtracted from its depth-averaged freezing point. In this study, the authors considered the combined nonlinear effects of vertical structures of frazil ice concentration and thermal forcing within an ISW plume by introducing equilibrium vertical profiles of frazil ice concentration into a horizontal two-dimensional depth-integrated ISW plume model. A series of idealized numerical experiments and an observation-based simulation beneath the western side of Ronne Ice Shelf have been conducted by using the vertically modified and original depth-integrated ISW plume models. It was found that the supercooled area, supercooling level, and suspended frazil ice and marine ice productivities are all substantially underestimated by the original models. Moreover, the differences are sensitive to the selected frazil ice size configuration. These results suggest that the vertical modification introduced in this study can significantly improve simulated marine ice distribution and its corresponding production, in comparison with those estimated by previous depth-integrated models.

scholarly journals Response of sub-ice platelet layer thickening rate to variations in Ice Shelf Water supercooling in McMurdo Sound, Antarctica

2018 ◽  
Author(s):  
Chen Cheng ◽  
Adrian Jenkins ◽  
Paul R. Holland ◽  
Zhaomin Wang ◽  
Chengyan Liu ◽  
...  
Keyword(s):  
Nonlinear Effects ◽  
Crystallographic Structure ◽  
Shelf Water ◽  
Ice Shelf ◽  
Mcmurdo Sound ◽  
Frazil Ice ◽  
Ice Concentration ◽  
Vertical Distributions ◽  
Ice Shelf Water ◽  
The Vertical Distribution

Abstract. Persistent outflow of supercooled Ice Shelf Water (ISW) from beneath McMurdo Ice Shelf creates a sub-ice platelet layer (SIPL) having a unique crystallographic structure under the sea ice in McMurdo Sound (MMS), Antarctica. A new frazil-ice-laden ISW plume model that encapsulates the combined nonlinear effects of the vertical distributions of supercooling and frazil ice concentration (FIC) on frazil ice growth is applied to MMS, and is shown to reproduce the observed ISW supercooling and SIPL distributions. Using this model, the dependence of SIPL thickening rate on ISW supercooling in MMS is investigated. Results are found to be sensitive to the choice of frazil ice suspension index, which determines the vertical distribution of FIC. For each suspension index, SIPL thickening rate can be expressed as an exponential function of ISW supercooling. The complex dependence on FIC highlights the need to improve frazil ice observations within the ice-ocean boundary layer.

scholarly journals The Effects of Rotation and Ice Shelf Topography on Frazil-Laden Ice Shelf Water Plumes

2006 ◽  
Vol 36 (12) ◽  
pp. 2312-2327 ◽  
Author(s):  
Paul R. Holland ◽  
Daniel L. Feltham
Keyword(s):  
Freezing Temperature ◽  
Shelf Water ◽  
Ice Shelf ◽  
Ice Dynamics ◽  
Frazil Ice ◽  
Ice Shelf Water ◽  
Effects Of Rotation ◽  
Realistic Topography ◽  
First Time

Abstract A model of the dynamics and thermodynamics of a plume of meltwater at the base of an ice shelf is presented. Such ice shelf water plumes may become supercooled and deposit marine ice if they rise (because of the pressure decrease in the in situ freezing temperature), so the model incorporates both melting and freezing at the ice shelf base and a multiple-size-class model of frazil ice dynamics and deposition. The plume is considered in two horizontal dimensions, so the influence of Coriolis forces is incorporated for the first time. It is found that rotation is extremely influential, with simulated plumes flowing in near-geostrophy because of the low friction at a smooth ice shelf base. As a result, an ice shelf water plume will only rise and become supercooled (and thus deposit marine ice) if it is constrained to flow upslope by topography. This result agrees with the observed distribution of marine ice under Filchner–Ronne Ice Shelf, Antarctica. In addition, it is found that the model only produces reasonable marine ice formation rates when an accurate ice shelf draft is used, implying that the characteristics of real ice shelf water plumes can only be captured using models with both rotation and a realistic topography.

scholarly journals Observations of the Size Distribution of Frazil Ice in an Ice Shelf Water Plume

2020 ◽  
Vol 47 (21) ◽  
Author(s):  
Eamon K. Frazer ◽  
Pat J. Langhorne ◽  
Greg H. Leonard ◽  
Natalie J. Robinson ◽  
Dániel Schumayer
Keyword(s):  
Size Distribution ◽  
Shelf Water ◽  
Ice Shelf ◽  
Frazil Ice ◽  
Ice Shelf Water

scholarly journals Responses of sub-ice platelet layer thickening rate and frazil-ice concentration to variations in ice-shelf water supercooling in McMurdo Sound, Antarctica

2019 ◽  
Vol 13 (1) ◽  
pp. 265-280 ◽  
Author(s):  
Chen Cheng ◽  
Adrian Jenkins ◽  
Paul R. Holland ◽  
Zhaomin Wang ◽  
Chengyan Liu ◽  
...  
Keyword(s):  
Sea Ice ◽  
Crystallographic Structure ◽  
Shelf Water ◽  
Ice Shelf ◽  
Mcmurdo Sound ◽  
Frazil Ice ◽  
Ice Concentration ◽  
Vertical Distributions ◽  
Linear Effects ◽  
Ice Shelf Water

Abstract. Persistent outflow of supercooled ice-shelf water (ISW) from beneath McMurdo Ice Shelf creates a rapidly growing sub-ice platelet layer (SIPL) with a unique crystallographic structure under the sea ice in McMurdo Sound, Antarctica. A vertically modified frazil-ice-laden ISW plume model that encapsulates the combined non-linear effects of the vertical distributions of supercooling and frazil concentration on frazil-ice growth is applied to McMurdo Sound and is shown to reproduce the observed ISW supercooling and SIPL distributions. Using this model, the dependence of the SIPL thickening rate and depth-averaged frazil-ice concentration on ISW supercooling in McMurdo Sound is investigated and found to be predominantly controlled by the vertical distribution of frazil concentration. The complex dependence on frazil concentration highlights the need to improve frazil-ice observations within the sea-ice–ocean boundary layer in McMurdo Sound.

scholarly journals Dynamics of Large Pelagic Ice Crystals in an Antarctic Ice Shelf Water Plume Flowing Beneath Land-Fast Sea Ice

2020 ◽  
Author(s):  
Craig Stevens ◽  
Natalie Robinson ◽  
Gabby O'Connor ◽  
Brett Grant
Keyword(s):  
Boundary Layer ◽  
Sea Ice ◽  
Tidal Flow ◽  
Ice Crystals ◽  
Large Individual ◽  
Turbulence Structure ◽  
Shelf Water ◽  
Ice Shelf ◽  
Turbulent Dissipation ◽  
Ice Shelf Water

Abstract. Observations of boundary-layer processes and ice crystal behaviour in an outflow region from the Ross/McMurdo Ice Shelves are presented. From a fast ice field camp, we captured the kinematics of free-floating relatively large (many 10s of mm in scale) ice crystals that were advecting as well as aggregating in a depositional layer on the sea ice underside (SIPL, sub-ice platelet layer). Simultaneously, we measured the background oceanic temperature, salinity, currents and turbulence structure. At the camp location the total water depth was 536 m, with the uppermost 50 m being in-situ super-cooled. Tidal flow speeds had an amplitude of around 0.1 m s−1 and the resulting under-ice boundary layer sustained turbulent dissipation rates as large as ϵ = 10−6 W kg−1. Acoustic sampling (200 kHz) identified three classes of backscatter (1) large individual highly mobile targets, (2) echoes from large, individually identifiable suspended crystals and (3) a varying background, presumably of very small (frazil) crystals. This second class of backscatter was associated with crystal sizes far larger than typical, certainly larger than anything normally described as frazil, and some individuals at least were depositing close to fully grown. Measurement indicated crystal scales of the range 30–80 mm. The existence and settlement of this scale of crystal has implications for understanding SIPL evolution and the processes controlling the fate of Ice Shelf Water.

scholarly journals Observations of the size distribution of frazil ice in an Ice Shelf Water plume

2020 ◽  
Author(s):  
Eamon K Frazer ◽  
Patricia Jean Langhorne ◽  
Greg H Leonard ◽  
Natalie Joy Robinson ◽  
Daniel Schumayer
Keyword(s):  
Size Distribution ◽  
Shelf Water ◽  
Ice Shelf ◽  
Frazil Ice ◽  
Ice Shelf Water
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