Modelling mixing and circulation in subglacial Lake Vostok, Antarctica

Thoma, Malte; Grosfeld, Klaus; Mayer, Christoph

doi:10.1007/s10236-007-0110-9

Cited by 27 publications

(48 citation statements)

References 33 publications

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“…s coordinate is convenient in representing an irregular bottom topography and making it smooth. The s coordinate is widely used in numerical models, especially for places with steep topographies such as lakes and coastal areas [19][20][21][22] .…”

Section: Methodsmentioning

confidence: 99%

Numerical study of hydrodynamic process in Chaohu Lake

Chen

Liu

2015

J Hydrodyn

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Abstract:In this paper, the hydrodynamic characteristics of water flow in Chaohu Lake are studied by using the finite volume coastal ocean model (FVCOM), which is verified by the observed data. The typical flow field and the 3-D flow structure are obtained for the lake. The flow fields under extreme conditions are analyzed to provide a prospective knowledge of the water exchange and the transport process.The influence of the wind on the flow is determined by the cross spectrum method. The results show that the wind-driven flow dominates most area of the lake. Under prevailing winds in summer and winter, the water flows towards the downwind side at the upper layer while towards the upwind side at the lower layer in most area except that around the Chaohu Sluice. The extreme wind speed is not favorable for the water exchange while the sluice's releasing water accelerates the process. The water velocity in the lake is closely related with the wind speed.

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Section: Methodsmentioning

confidence: 99%

Numerical study of hydrodynamic process in Chaohu Lake

Chen

Liu

2015

J Hydrodyn

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“…Details about the numerical ocean/lake flow model Rombax are described in Grosfeld et al (1997) and Thoma et al (2006Thoma et al ( , 2007aThoma et al ( , 2008b); here we concentrate on the differences between the set up used to model Lake Vostok and the set up applied in this study. Lake Concordia's area (volume) is only 3.6% (0.6%) of Lake Vostok's; hence we increased the horizontal resolution of our flow model Rombax by four (resulting in a grid size of about 0.8 km×1.4 km) to obtain a reasonable number of nodes.…”

Section: Geometry and Numerical Model Setupmentioning

confidence: 99%

“…These values represent the macroscopic diffusion of momentum, which cannot be resolved by this type of circulation models, and are closely related to the grid size. As in Thoma et al (2007a), several parametrizations of the horizontal (A h ) and vertical (A v ) eddy viscosities have been tested. Finally we applied viscosities which are four times lower than those used to model Lake Vostok (A h =5 m 2 /s, A v =0.025 cm 2 /s).…”

Section: Geometry and Numerical Model Setupmentioning

confidence: 99%

“…A Prandtl number of unity is choosen, which results in identical values for the diffusion of heat. According to Thoma et al (2007a), this is suitable for the modelling of subglacial lakes. In the vertical, sixteen terrain-following layers with a minimum thickness of 0.5 m are used.…”

Section: Geometry and Numerical Model Setupmentioning

confidence: 99%

“…However, comparisons with these early models showed, that only with sophisticated 3D-models and a realistic bathymetry sensible results can be expected (Thoma et al, 2007a). Successive studies, applying the most reasonable boundary conditions, have investigated the circulation, the mass balance at the ice-lake interface, the tracer dispersion within the lake, and the amount of accreted ice at the icelake interface for Lake Vostok (Thoma et al, 2007a(Thoma et al, ,b, 2008aFilina et al, 2008), but no adequate information (e.g., water depth, ice thickness, grounding line, heat fluxes) was available about any other subglacial lake until now. In this study we turn towards Lake Concordia which is located near Dome C at 74.0 • S and 125.2 • E (see inlet in Figure 1a) and many times smaller than Lake Vostok.…”

Section: Introductionmentioning

confidence: 99%

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Modelling flow and accreted ice in subglacial Lake Concordia, Antarctica

Thoma

Grosfeld

Filina

et al. 2009

Earth and Planetary Science Letters

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More than 150 subglacial lakes have been discovered in Antarctica so far. Due to obvious challenges with exploration, numerical modelling remains one of the major tools to acquire information about those hard-to-access objects. Until now only the huge Lake Vostok has been investigated in detail. This paper focuses on Lake Concordia -the second largest subglacial lake in Antarctica over which substantial geophysical data has been collected. This lake is covered by about 4000 m ice and is located near Dome C. In order to apply numerical models to the hard-to-access Antarctic subglacial lakes, decent geometries and boundary conditions are required. In this study we present the results of airborne gravity inversion, suggesting that this lake has an area of 617 km 2 , a volume of 31 km 3 , and a maximum water column thickness of 126 m. This bathymetry is used as geometry input for an established 3D-numerical lake-flow model to simulate the circulation and basal mass balance. Compared to our model studies of subglacial Lake Vostok, we obtain a general circulation pattern that is significantly weaker (due to the smaller size of the lake) and of reversed orientation (due to the reversed ice surface tilt). The modelled mean horizontal and vertical velocities are in the order of 0.2 mm/s and 0.5 µm/s, respectively. The larger molecular convective velocity estimations (1.35 ± 0.13 mm/s and 0.81 ± 0.08 mm/s) are similar to Lake Vostok's. The modelled average melting and freezing rates are 4.3±1.1 mm/a and 1.1±0.3 mm/a, respectively, and the corresponding fresh water gain is 58±27 dm 3 /s. Integration of the modelled freezing and melting along prescribed ice flow lines allows us to calculate the distribution and thickness of accreted ice at the ice sheet bottom. We estimate a volume of 2.6±2.0 km 3 (8.3 ± 8.2% of the total lake volume) occupying the north-eastern corner of the lake covering an area of 159±48 km 2 (26 ± 9% of the total lake area). With about 16 800±7 600 years, the residence time of the lake's water is significantly shorter than Lake Vostok's.

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Height changes over subglacial Lake Vostok, East Antarctica: Insights from GNSS observations

et al. 2014

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Height changes of the ice surface above subglacial Lake Vostok, East Antarctica, reflect the integral effect of different processes within the subglacial environment and the ice sheet. Repeated GNSS (Global Navigation Satellite Systems) observations on 56 surface markers in the Lake Vostok region spanning 11 years and continuous GNSS observations at Vostok station over 5 years are used to determine the vertical firn particle movement. Vertical marker velocities are derived with an accuracy of 1 cm/yr or better. Repeated measurements of surface height profiles around Vostok station using kinematic GNSS observations on a snowmobile allow the quantification of surface height changes at 308 crossover points. The height change rate was determined at 1 ± 5 mm/yr, thus indicating a stable ice surface height over the last decade. It is concluded that both the local mass balance of the ice and the lake level of the entire lake have been stable throughout the observation period. The continuous GNSS observations demonstrate that the particle heights vary linearly with time. Nonlinear height changes do not exceed ±1 cm at Vostok station and constrain the magnitude of spatiotemporal lake-level variations. ICESat laser altimetry data confirm that the amplitude of the surface deformations over the lake is restricted to a few centimeters. Assuming the ice sheet to be in steady state over the entire lake, estimates for the surface accumulation, on basal accretion/melt rates and on flux divergence, are derived.

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Modelling mixing and circulation in subglacial Lake Vostok, Antarctica

Cited by 27 publications

References 33 publications

Numerical study of hydrodynamic process in Chaohu Lake

Numerical study of hydrodynamic process in Chaohu Lake

Modelling flow and accreted ice in subglacial Lake Concordia, Antarctica

Height changes over subglacial Lake Vostok, East Antarctica: Insights from GNSS observations

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