Various theoretical and numerical models have been applied in the past 2 decades to describe the maintenance and feeding of the Arctic cold halocline and deeper layers by dense, saline water masses produced on the circum-Arctic shelves subsequent to ice formation [e.g., Bjørk, 1989; Jones and Anderson, 1986; Chapman, 1999; Signorini and Cavalieri, 2002; Winsor and Chapman, 2002]. Becker and Bjørk  described the transformation of shelf surface mixed-layer water to different types of higher saline waters and their interleaving in the model water column at their respective level of neutral density. The authors estimated a total rate of 0.8 Sv of cold, high-salinity water produced on the Arctic shelves.
 Gawarkiewicz and Chapman , Chapman and Gawarkiewicz , Chapman , and Gawarkiewicz  developed theoretical, several-step models describing the production and offshore flux of freeze-related dense brines in idealized high-latitude coastal polynya areas. The model results suggest an initial stage of geostrophic adjustment associated with dense water accumulation within the polynya water body subsequent to continuous constant negative buoyancy forcing, followed by frontal meandering instabilities equalizing coastal constraints, which then finally lead to the development of cross-shelf eddy fluxes transporting polynya-produced dense water offshore. In contrast to the above theoretical Gwarkiewicz and Chapman model predictions that dense polynya water is transported offshore by eddies, Danielson et al.  found in the shallow, gently sloping St. Lawrence polynya area that this mechanism of cross-shelf brine flux was negligible and that dense water was rather advected offshore before significant eddy fluxes could establish.
 Salt release and subsequent dense brine rejection during continuous ice formation in Siberian and western Arctic flaw leads (Figure 1; elongated open water between fast ice and drift ice) may locally and temporarily contribute strongly to the maintenance of the cold halocline and to the renewal of Intermediate and deep water [e.g., Aagaard et al., 1981; Martin and Cavalieri, 1989; Cavalieri and Martin, 1994; Winsor and Björk, 2000]. Aagaard et al.  estimated ice growth rates in divergent ice zones on the circum-Arctic shelves required to raise the local water salinity high enough to feed the cold halocline layer (assumed salinity of 33.5). The authors proposed that the most effective areas to produce cold halocline water are located between Spitsbergen and Franz Josef Land, west of Novaya Zemlya (Barents Sea), and west of Severnaya Zemlya (Kara Sea).
 Midttun  reported 34.95 salinity bottom water west of Novaya Zemlya and attributed this phenomenon to winter freezing. This was corroborated by model results from Harms  showing the connection between local polynyas and dense water formation off the west coast of Novaya Zemlya. Martin and Cavalieri  and Cavalieri and Martin  estimated the salt rejection and dense water production in Russian, Siberian, and western Arctic shelf polynyas (flaw leads) in more detail. According to their calculations, both Siberian and Alaskan Arctic polynyas together generate about 0.7–1.2 Sv of dense water annually. Melling  found that flaw leads on the Mackenzie shelf contribute substantially to the annual shelf flux of roughly 0.04 Sv of dense water to the Arctic cold halocline. The flux is proportional to the fraction of the Arctic shelf area that the considered region represented. Winsor and Björk  modeled circum-Arctic polynya ice formation events and related salt flux for a period of 4 decades. They found that the mean multidecadal polynya salt flux can sustain a flow of 0.2 Sv dense water, representing ∼30% of the flux estimated to maintain the Arctic halocline layer.
1.2. Laptev Sea
 The Laptev Sea is one of the broadest and shallowest circum-Arctic Ocean shelf seas and is also among the most controversially discussed Arctic seas in terms of dense water formation related to flaw lead and polynya ice production. Early on, Zubov  proposed that the dense water produced in the Laptev Sea flaw lead may flow from the shelf down to greater water depths. Zakharov  reported that the Laptev Sea flaw lead salinity regionally increases by 2–6 units compared to the surrounding shelf water through intense winter ice extraction. Aagaard et al.  concluded that the inner Laptev Sea summer salinities “are generally too low to allow a winter production of water sufficiently saline to feed the halocline.” However, they also suggested that the outer shelf area might be a dense water source. Martin and Cavalieri  and Cavalieri and Martin  studied dense lead water production in the western and northeastern Laptev Sea but neglected extended lead sections on the central-southern and eastern Laptev shelf, as they were unknown to the authors at that time. Cavalieri and Martin  came up with a total brine flux of 0.7–1.2 Sv from all circum-Arctic shelf polynyas investigated in that study, with ∼0.12 Sv (10%–17%) forming by brine rejection from the flaw leads in the western Laptev Sea along the eastern Severnaya Zemlya and Taymyr Peninsula coasts (Figure 1).
 Schauer et al.  concluded that the Barents and Kara seas are the only source areas for shelf waters ventilating the Nansen Basin below the cold halocline and that winter shelf water from the Laptev Sea cannot contribute to layers deeper than the upper halocline. Controversially, Ivanov et al.  and Ivanov and Golovin  identified extended parts of the northwestern Laptev Sea shelf east off Severnay Zemlya as region where freeze-related dense brines (∼0.02 Sv) are cascading down the shelf slope and ventilating salt into deeper layers of the Nansen Basin.
 Winsor and Björk  estimated a four decadal average annual salt flux of ∼32.5 × 1011 kg from 28 extended circum-Arctic shelf polynya areas, to which western, central southern, and northeastern Laptev Sea flaw leads contribute ∼28% (∼9 × 1011 kg). However, there is an exceptionally weak salt contribution from central southern Laptev flaw leads situated near the Olenek and Lena river mouths (Figure 1). Conversely, in a model study, Johnson and Polyakov  identified the southern central shelf area as a source for the salinization of the Laptev Sea and for the alteration of the Eurasian Basin cold halocline water formation during the 1990s. The authors related this to enhanced dense brine rejection subsequent to strong ice growth in flaw leads. Dethleff  reached a different conclusion following a detailed investigation of 46 circum-Arctic flaw leads. The author showed that the central southern and southeastern Laptev Sea flaw leads produce relatively little salt due to low initial salinities combined with reduced seasonal ice production rates as winter offshore fast ice development regularly closes the southeastern Laptev leads by November to late December [Dethleff et al., 1998].
1.3. Purpose of the Study
 The purpose of this study was to provide a detailed estimate of freeze-related salt production from the surface mixed water (SMW) in 14 individual Laptev Sea flaw lead sections based on historic ice formation rates (volumes) and salinity data. Furthermore, the theoretic contribution of the individual lead sections to the maintenance of the local cold halocline water (CHW; salinity, 34.20) and to the renewal of intermediate water (IMW; salinity, 34.75) and deep water masses (DW; salinity, 34.93) are investigated using two different idealized equation-based models (Figure 2).
 Although Gawarkiewicz and Chapman , Chapman and Gawarkiewicz , and Chapman  and Gawarkiewicz  developed a series of universal, complex, and dynamic numerical models of dense water formation and eddie-driven offshore transport in idealized polynyas on shallow, sloping continental shelves, the target of this study is to present rather simplified, more static model approaches easily allowing the comparison of the outcome with results of various other studies dealing particularly with the Laptev Sea region during the past 2 decades [Becker and Bjørk, 1996; Martin and Cavalieri, 1989; Cavalieri and Martin, 1994; Winsor and Björk, 2000; Johnson and Polyakov, 2001; Dethleff, 2010]. The above Gawarkiewicz and Chapman studies will be discussed in relation to the model results presented and to potential transport processes of dense water away from the Laptev Sea flaw lead system down the continental slope.
 Model A considers the rejection of salt (dense brines) through lead-ice extraction, and the remixing of the salt with shallow lead water until the salinity and density increases to the level where the water sinks to the deeper layers (CHW, IMW, DW). In contrast, model B assumes direct downward rejection of dense lead brines as “pockets” or “parcels.” These dense brine parcels sink through the shallow lead water without mixing until reaching the cold halocline boundary. Mixing occurs at this boundary quasi en route, producing dense water that contributes to the deeper water masses. The models are described in detail in section 2. The model results are presented in section 3 and discussed in section 4. The latter section further discusses the possible upwelling of higher saline Atlantic water during storm events particularly into western Laptev lead sections and its significance for the process of dense water production.