Ocean Heat Flux in the Central Weddell Sea during Winter

McPhee, Miles G.; Kottmeier, C.; Morison, James H.

doi:10.1175/1520-0485(1999)029<1166:ohfitc>2.0.co;2

Cited by 118 publications

(164 citation statements)

References 21 publications

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“…Moving away towards the west, the heat content declines again. The equivalent average heat fluxes calculated are similar to the average values of 20-30 Wm −2 reported from the ANZFLUX Experiment (McPhee et al 1999;Muench et al 2001). The calculations in Table 2 show that a modest deepening of the surface layer by 10-15 m is sufficient to satisfy this requirement.…”

Section: Hydrographysupporting

confidence: 81%

“…Many studies of the Maud Rise region, particularly those associated with the Antarctic Zone Flux Experiment (McPhee et al 1996(McPhee et al , 1999McPhee 2000;Muench et al 2001) have been concerned with the detail of exchange processes. In this paper, we do not set out to detract from that work but instead adopt a new approach by posing a different question: If, as is often the case in modelling large-scale ocean flows, we need to represent the observed decrease in potential temperature variance on isopycnic surfaces as time progresses by a diffusive process, how big should the isopycnic and diapycnic eddy diffusivities be?…”

Section: Introductionmentioning

confidence: 99%

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Modification by lateral mixing of the Warm Deep Water entering the Weddell Sea in the Maud Rise region

2010

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Deep water originating in the North Atlantic is transported across the Antarctic Circumpolar Current by eddies and, after circumnavigating of the Antarctic, enters the Weddell Gyre south of Africa. As it does so, it rises up from mid-depth towards the surface. The separate temperature and salinity maxima, the Upper and Lower Circumpolar Deep Waters, converge to form the Warm Deep Water. Cores of this water mass on the southern flank of the eastern Weddell Gyre show a change in characteristic as they flow westward in the Lazarev Sea. Observations have been made along four meridional sections at 3°E, 0°, 3°W and 6°W between 60 and 70°S during the Polarstern Cruise ANTXXIII/2 in 2005/2006. These show that a heterogeneous series of warm and salty cores entering the region from the east both north and south of Maud Rise (65°S, 3°W) gradually merge and become more homogeneous towards the west. The gradual reduction in the variance of potential temperature on isopycnals is indicative of isopycnic mixing processes. A multiple regression technique allows diagnosis of the eddy diffusivities and, thus, the relative importance of isopycnic and diapycnic mixing. The method shows that the isopycnic diffusivity lies in the range 70-140 m 2 s −1 and the diapycnic diffusivity reaches about 3×10 −6 m 2 s −1 . Scale analysis suggests that isopycnic diffusion dominates over diapycnic diffusion in the erosion of the Warm Deep Water cores.

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Section: Hydrographysupporting

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Modification by lateral mixing of the Warm Deep Water entering the Weddell Sea in the Maud Rise region

2010

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“…Compared with submarine observations of arctic ice draft (Rothrock et al 1999), Antarctic sea ice is significantly thinner than its arctic counterpart. The thinner Antarctic ice cover may be due to a less stratified Southern Ocean; considerably more ocean heat flux is generated than in the Arctic Ocean (McPhee et al 1999;Maykut and McPhee 1995). The simulated ice thickness (H ) increases from 1979 to 2004 in most of the ice-covered areas in the Southern Ocean (defined hereafter as the 1979-2004 mean satellite-observed sea ice extent shown in Fig.…”

Section: A Increasing Sea Ice Volumementioning

confidence: 99%

Increasing Antarctic Sea Ice under Warming Atmospheric and Oceanic Conditions

2007

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Estimates of sea ice extent based on satellite observations show an increasing Antarctic sea ice cover from 1979 to 2004 even though in situ observations show a prevailing warming trend in both the atmosphere and the ocean. This riddle is explored here using a global multicategory thickness and enthalpy distribution sea ice model coupled to an ocean model. ) in sea ice extent during the same period. The model shows that an increase in surface air temperature and downward longwave radiation results in an increase in the upper-ocean temperature and a decrease in sea ice growth, leading to a decrease in salt rejection from ice, in the upper-ocean salinity, and in the upper-ocean density. The reduced salt rejection and upper-ocean density and the enhanced thermohaline stratification tend to suppress convective overturning, leading to a decrease in the upward ocean heat transport and the ocean heat flux available to melt sea ice. The ice melting from ocean heat flux decreases faster than the ice growth does in the weakly stratified Southern Ocean, leading to an increase in the net ice production and hence an increase in ice mass. This mechanism is the main reason why the Antarctic sea ice has increased in spite of warming conditions both above and below during the period 1979-2004 and the extended period 1948-2004.

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“…This works well within HadCM3, but clearly owes more to simplicity than physical reality. A more physical version, referred to here as the "P-scheme" (P for proportional), increases the diffusivity, K, from 2.5×10 −5 m 2 s −1 to 2.5×10 −4 m 2 s −1 (in better agreement with observations; McPhee et al, 1999) and makes the heat fluxes proportional to the ice fraction.…”

Section: The Ice-ocean Heat Fluxmentioning

confidence: 72%

Results from the implementation of the Elastic Viscous Plastic sea ice rheology in HadCM3

2006

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Abstract. We present results of an implementation of the Elastic Viscous Plastic (EVP) sea ice dynamics scheme into the Hadley Centre coupled ocean-atmosphere climate model HadCM3. Although the large-scale simulation of sea ice in HadCM3 is quite good with this model, the lack of a full dynamical model leads to errors in the detailed representation of sea ice and limits our confidence in its future predictions. We find that introducing the EVP scheme results in a worse initial simulation of the sea ice. This paper documents various enhancements made to improve the simulation, resulting in a sea ice simulation that is better than the original HadCM3 scheme overall. Importantly, it is more physically based and provides a more solid foundation for future development. We then consider the interannual variability of the sea ice in the new model and demonstrate improvements over the HadCM3 simulation.

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Ocean Heat Flux in the Central Weddell Sea during Winter

Cited by 118 publications

References 21 publications

Modification by lateral mixing of the Warm Deep Water entering the Weddell Sea in the Maud Rise region

Modification by lateral mixing of the Warm Deep Water entering the Weddell Sea in the Maud Rise region

Increasing Antarctic Sea Ice under Warming Atmospheric and Oceanic Conditions

Results from the implementation of the Elastic Viscous Plastic sea ice rheology in HadCM3

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