Sea-ice thermodynamics and brine drainage

Worster, M. Grae; Jones, David Rees

doi:10.1098/rsta.2014.0166

Cited by 48 publications

(66 citation statements)

References 17 publications

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“…The characteristic time scale for an

O (1)

change in ice thickness due to mechanical aggregation is

τ_{m} \approx | \nabla \cdot u |^{- 1} \approx 20

days, assuming a typical length scale of

\sim 200

km and an ice velocity of

\sim 0.1 m \cdot s^{- 1}

[ Samelson et al ., ]. On the other hand, the a similar change in ice thickness due to freezing seawater takes a typical time

τ_{f} = ρ_{i} L h^{2} / (κ (T_{a} - T_{f}))

, where L is the latent heat of fusion per volume, κ is the thermal conductivity of sea ice, T a is the atmospheric temperature and T f is the freezing temperature of seawater [ Leppäranta , ; Worster and Rees Jones , ]. For a typical value of

ρ_{i} L / κ \approx 0.2 ° C \cdot d a y \cdot {cm}^{- 2}

[ Leppäranta , ], a temperature difference

(T_{a} - T_{f}) \sim 20 °

C characteristic of Nares Strait [ Ryan and Münchow , ], and meter‐thick ice, we find

τ_{f} \approx 90

days.…”

Section: Sea Ice Dynamics and Rheologymentioning

confidence: 99%

Formation of sea ice bridges in narrow straits in response to wind and water stresses

2017

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Ice bridges are rigid structures composed of sea ice that form seasonally in the many straits and channels of the Canadian Arctic Archipelago. Driven primarily by atmospheric stresses, these ice bridges are formed when sufficiently thick ice “jams” during the course of its flow between land masses, resulting in a region of stationary compacted ice that is separated from a region of flowing open water (a polynya) by a static arch. Using a continuum description of sea ice that is widely used in climate modeling, we present an asymptotic theory of the process of formation of such bridges in slender channels when the motion of the ice is driven by external wind and water stresses. We show that for an arbitrary channel shape, ice bridges can only form within a range of ice properties that is determined by the channel geometry and the external stress. We then compare the results of our theory with direct numerical simulations and observational evidence. Finally, we provide simple analytical expressions for the mean velocity of the ice flow as a function of the channel shape, the properties of the ice, and the wind and water stresses along the channel.

show abstract

“…The characteristic time scale for an

O (1)

change in ice thickness due to mechanical aggregation is

τ_{m} \approx | \nabla \cdot u |^{- 1} \approx 20

days, assuming a typical length scale of

\sim 200

km and an ice velocity of

\sim 0.1 m \cdot s^{- 1}

[ Samelson et al ., ]. On the other hand, the a similar change in ice thickness due to freezing seawater takes a typical time

τ_{f} = ρ_{i} L h^{2} / (κ (T_{a} - T_{f}))

ρ_{i} L / κ \approx 0.2 ° C \cdot d a y \cdot {cm}^{- 2}

[ Leppäranta , ], a temperature difference

(T_{a} - T_{f}) \sim 20 °

C characteristic of Nares Strait [ Ryan and Münchow , ], and meter‐thick ice, we find

τ_{f} \approx 90

days.…”

Section: Sea Ice Dynamics and Rheologymentioning

confidence: 99%

Formation of sea ice bridges in narrow straits in response to wind and water stresses

2017

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“…Griewank and Notz (), Turner et al (), and Rees Jones and Worster () parameterize gravity drainage as a convective process and formulate the velocity of moving brine using the Rayleigh number. Worster and Rees Jones () show that these parameterizations are broadly similar. Vancoppenolle et al () parameterize gravity drainage as a diffusive process, using a Rayleigh number to set the strength of the diffusion.…”

Section: Introductionmentioning

confidence: 90%

“…The downwelling brine channel mass flux provides a direct connection between the sea ice interior and the ocean and is linearly dependent on the local Rayleigh number. Following Worster and Rees Jones (), we show in Appendix that the original Griewank and Notz () formulation can be recast into a vertical salt advection equation formally identical to equation , provided that the upwelling velocity in the

k

th layer is defined as

w_{k} = - \frac{α_{GN}}{ρ} true \sum_{i = 1}^{k} false(R a_{i} - R a_{normalc} false) normalΔ z_{i} .

…”

Section: Modeling Gravity Drainage As a 1‐d Vertical Processmentioning

confidence: 99%

“…The dominant process redistributing brine within growing sea ice and exchanging brine with the ocean is gravity drainage (Notz & Worster, ). As such, gravity drainage exerts a control on the habitable volume (Vancoppenolle et al, ), nutrient budget (Fripiat et al, ; Fritsen et al, ), and inorganic carbon budget (König et al, ; Moreau et al, ) in growing sea ice, as well as determining the buoyancy forcing provided by growing sea ice to the ocean (Pellichero et al, ; Worster & Rees Jones, ).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Tracer Measurements in Growing Sea Ice Support Convective Gravity Drainage Parameterizations

et al. 2020

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Gravity drainage is the dominant process redistributing solutes in growing sea ice. Modeling gravity drainage is therefore necessary to predict physical and biogeochemical variables in sea ice. We evaluate seven gravity drainage parameterizations, spanning the range of approaches in the literature, using tracer measurements in a sea ice growth experiment. Artificial sea ice is grown to around 17 cm thickness in a new experimental facility, the Roland von Glasow air‐sea‐ice chamber. We use NaCl (present in the water initially) and rhodamine (injected into the water after 10 cm of sea ice growth) as independent tracers of brine dynamics. We measure vertical profiles of bulk salinity in situ, as well as bulk salinity and rhodamine in discrete samples taken at the end of the experiment. Convective parameterizations that diagnose gravity drainage using Rayleigh numbers outperform a simpler convective parameterization and diffusive parameterizations when compared to observations. This study is the first to numerically model solutes decoupled from salinity using convective gravity drainage parameterizations. Our results show that (1) convective, Rayleigh number‐based parameterizations are our most accurate and precise tool for predicting sea ice bulk salinity; and (2) these parameterizations can be generalized to brine dynamics parameterizations, and hence can predict the dynamics of any solute in growing sea ice.

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“…Worster & Rees Jones [6] note the new dominance of younger firstyear sea ice in the Arctic Ocean and discuss how salt loss from such ice is improperly accounted for in the existing generation of climate models. A new model of salt release is described, promising to enhance simulations of buoyancy forcing of the Arctic Ocean.…”

mentioning

confidence: 99%

Arctic sea ice reduction: the evidence, models and impacts

Feltham

2015

Phil. Trans. R. Soc. A.

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Sea-ice thermodynamics and brine drainage

Cited by 48 publications

References 17 publications

Formation of sea ice bridges in narrow straits in response to wind and water stresses

Formation of sea ice bridges in narrow straits in response to wind and water stresses

Tracer Measurements in Growing Sea Ice Support Convective Gravity Drainage Parameterizations

Arctic sea ice reduction: the evidence, models and impacts

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