Sensitivity studies on vortex development over a polynya

Hebbinghaus, Heike; Schlünzen, Heinke; Dierer, Silke

doi:10.1007/s00704-006-0233-9

Cited by 7 publications

(5 citation statements)

References 31 publications

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“…For low wind conditions and strong cold temperatures (C2, C3), mesoscale cyclones or mesoscale troughs develop over the western Laptev Sea, which are strongest for runs including ice-free polynyas. This agrees well with simulations made by Hebbinghaus et al (2007). They found that a vortex over a polynya area being best developed for weak large-scale pressure gradients.…”

Section: Discussionsupporting

confidence: 91%

“…The energy input into the atmosphere changes the structure of the stable ABL dramatically. Developments of mesocyclones have been observed over polynyas (Heinemann 1996;Hebbinghaus et al 2007). A couple of numerical simulations have been done in the past using different micro-and mesoscale models to investigate the impact of polynyas and leads on the ABL at high latitudes (Gallé e 1997;Dare & Atkinson 2000;Heinemann 2003;Lü pkes, Vihma et al (a) (b) Fig.…”

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confidence: 99%

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Impact of Laptev Sea flaw polynyas on the atmospheric boundary layer and ice production using idealized mesoscale simulations

2011

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The interaction between polynyas and the atmospheric boundary layer is examined in the Laptev Sea using the regional, non-hydrostatic Consortium for Small-scale Modelling (COSMO) atmosphere model. A thermodynamic sea-ice model is used to consider the response of sea-ice surface temperature to idealized atmospheric forcing. The idealized regimes represent atmospheric conditions that are typical for the Laptev Sea region. Cold wintertime conditions are investigated with sea-ice–ocean temperature differences of up to 40 K. The Laptev Sea flaw polynyas strongly modify the atmospheric boundary layer. Convectively mixed layers reach heights of up to 1200 m above the polynyas with temperature anomalies of more than 5 K. Horizontal transport of heat expands to areas more than 500 km downstream of the polynyas. Strong wind regimes lead to a more shallow mixed layer with strong near-surface modifications, while weaker wind regimes show a deeper, well-mixed convective boundary layer. Shallow mesoscale circulations occur in the vicinity of ice-free and thin-ice covered polynyas. They are forced by large turbulent and radiative heat fluxes from the surface of up to 789 W m−2, strong low-level thermally induced convergence and cold air flow from the orographic structure of the Taimyr Peninsula in the western Laptev Sea region. Based on the surface energy balance we derive potential sea-ice production rates between 8 and 25 cm d−1. These production rates are mainly determined by whether the polynyas are ice-free or covered by thin ice and by the wind strength

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Section: Discussionsupporting

confidence: 91%

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confidence: 99%

Impact of Laptev Sea flaw polynyas on the atmospheric boundary layer and ice production using idealized mesoscale simulations

2011

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“…On the basis of airborne observations and high-resolution modelling, Lüpkes et al (2008bLüpkes et al ( , 2012b concluded that convection over 1-2 km wide leads reached altitudes of 50-300 m depending on the boundary layer structure on the upstream side of leads. On the basis of aircraft in situ, drop sonde, and lidar observations, Lampert et al (2012) observed that over areas with many leads, the potential temperature decreased with height in the lowermost 50 m and then was nearly constant due to convective mixing up to the height of 100-200 m. When the leads were frozen and their fraction was small, however, an SBL extended up to a height of 200-300 m. Ebner et al (2011) showed in a modelling study that convective plumes generated over the Laptev Sea polynya influence atmospheric turbulence even 500 km downstream of the polynya, and Hebbinghaus et al (2006) found that cyclonic vortices can be generated or intensified over polynyas due to convective processes. Such processes over large polynyas may be important with respect to the drastic changes in sea ice cover observed in recent years.…”

Section: Atmosmentioning

confidence: 99%

Advances in understanding and parameterization of small-scale physical processes in the marine Arctic climate system: a review

et al. 2014

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Abstract. The Arctic climate system includes numerous highly interactive small-scale physical processes in the atmosphere, sea ice, and ocean. During and since the International Polar Year 2007-2009, significant advances have been made in understanding these processes. Here, these recent advances are reviewed, synthesized, and discussed. In atmospheric physics, the primary advances have been in cloud physics, radiative transfer, mesoscale cyclones, coastal, and fjordic processes as well as in boundary layer processes and surface fluxes. In sea ice and its snow cover, advances have been made in understanding of the surface albedo and its relationships with snow properties, the internal structure of sea ice, the heat and salt transfer in ice, the formation of superimposed ice and snow ice, and the small-scale dynamics of sea ice. For the ocean, significant advances have been related to exchange processes at the ice-ocean interface, diapycnal mixing, double-diffusive convection, tidal currents and diurnal resonance. Despite this recent progress, some of these small-scale physical processes are still not sufficiently understood: these include wave-turbulence interactions in the atmosphere and ocean, the exchange of heat and salt at the ice-ocean interface, and the mechanical weakening of sea ice. Many other processes are reasonably well understood as stand-alone processes but the challenge is to understand their interactions with and impacts and feedbacks on other processes. Uncertainty in the parameterization of small-scale processes continues to be among the greatest challenges facing climate modelling, particularly in high latitudes. Further improvements in parameterization require new year-round field campaigns on the Arctic sea ice, closely combined with satellite remote sensing studies and numerical model experiments.

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“…We use the nonhydrostatic and anelastic atmospheric model METRAS [ Schlünzen , 1988, 1990] in a 2D version as applied earlier to cold air outbreaks by Lüpkes and Schlünzen [1996] and by Birnbaum and Lüpkes [2002] and to on‐ice flow regimes by Vihma et al [2003]. Its 3D version was applied to arctic regions by Dierer and Schlünzen [2005a, 2005b] and by Hebbinghaus et al [2006]. The model is originally a mesoscale model with horizontal grid spacing Δ x of at least 1 km in convective conditions.…”

Section: Model Descriptionmentioning

confidence: 99%

Modeling convection over arctic leads with LES and a non‐eddy‐resolving microscale model

et al. 2008

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[1] Turbulent heat transport over inhomogeneous surfaces with sharp temperature discontinuities is investigated with a focus on the flow over leads in sea ice. The main goal consists in the development of a turbulence closure for a microscale atmospheric model resolving the integrated effect of plumes emanated from leads, but not the individual convective eddies. To this end, 10 runs are carried out with a large eddy simulation (LES) model simulating the flow over leads for springtime atmospheric conditions with near-neutral inflow and a strong capping inversion. It is found that leads contribute to the stabilizing of the polar atmospheric boundary layer (ABL) and that strong countergradient fluxes of heat exist outside a core region of the plumes. These findings form the basis for the development of the new closure. It uses a new scaling with the internal ABL height and the characteristic vertical velocity for the plume region as the main governing parameters. Results of a microscale model obtained with the new closure agree well with the LES for variable meteorological forcing in case of lead orthogonal flow and for a fixed ABL height and lead width. The good agreement concerns especially the plume inclination, temperature, and heat fluxes as well as the relative contributions of gradient and countergradient transport of heat. A future more general closure should account, for example, for variable lead widths and wind directions. Results of the microscale model could be used to derive a future parameterization of the lead effect in large-scale models.Citation: Lüpkes, C., V. M. Gryanik, B. Witha, M. Gryschka, S. Raasch, and T. Gollnik (2008), Modeling convection over arctic leads with LES and a non-eddy-resolving microscale model,

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Sensitivity studies on vortex development over a polynya

Cited by 7 publications

References 31 publications

Impact of Laptev Sea flaw polynyas on the atmospheric boundary layer and ice production using idealized mesoscale simulations

Impact of Laptev Sea flaw polynyas on the atmospheric boundary layer and ice production using idealized mesoscale simulations

Advances in understanding and parameterization of small-scale physical processes in the marine Arctic climate system: a review

Modeling convection over arctic leads with LES and a non‐eddy‐resolving microscale model

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