The penetrative mixing in the Laptev Sea coastal polynya pycnocline layer

Abstract

a b s t r a c tThe large recurrent areas of open water and/or thin ice (polynyas) producing cold brine-enriched waters off the fast-ice edge are evident in the Laptev Sea in winter time. A number of abrupt positively correlated transitions in temperature and salinity were recorded in the bottom and intermediate layers at a mooring station in the West New Siberian (WNS) polynya in February-March 2008. Being in the range of ∼0.5 1C and ∼1.6 psu these changes are induced by horizontal motions across the polynya and correspond to temperature and salinity horizontal gradients in the range of 0.3-1.0 1C/10 km and 1.4-3.5 psu/10 km, respectively. The events of distinct freshening and temperature decrease coincide with a northward current off the fast-ice edge, while southward currents brought saltier and warmer waters at intermediate depths. We suggest that the observed transitions are connected to altering pycnocline depths across the polynya. The source of relatively fresher waters at the intermediate depths in polynya is supposed to originate from penetrative mixing of surface low salinity waters to intermediate water depth. Several forcing processes that could be responsible for a penetrative mixing through the density interface in polynya are discussed. These are penetrative convection and shear-driven mixing that originates from two-layer water dynamics and/or baroclinic tidal motions. The heavily ridged seaward fast-ice edge could produce an additional source of turbulent mixing even through a shear-free density interface due to the increased roughness at the ice-water interface.

The effect of ocean heat flux on seasonal ice growth in Young Sound (Northeast Greenland)

“…With a declining arctic ice pack solar heat input has been increasing within the Arctic, causing increased melting and prolonging the open water season [Stroeve et al, 2014]. However, over the significantly freshened Siberian shelves, the solar heat might be partly captured beneath the density interface and affects the seasonal sea ice on a long-term basis [Dmitrenko et al, 1999;Kirillov et al, 2013]. The ocean heat fluxes in the peripheral Arctic areas are traditionally associated with the advection of modified Atlantic waters to the ice-covered regions [McPhee et al, 2003;Polyakov et al, 2010;Ivanov et al, 2012;Linders and Bjork, 2013;Dmitrenko et al, 2014].…”

Resonant Penetrative Convection with an Internal Heat Source/Sink

“…In particular, the presence of a heat source or sink may give rise to the idea of penetrative convection where part of the layer has a tendency to move whereas the remainder of the layer will remain motionless until a certain point when movement in the rest of the layer "penetrates" into the stable layer and a resultant motion then ensues, cf. Altawallbeh et al [1], van den Berg et al [3], Berlengiero et al [4], Capone et al [5,6,7], Capone 1 & de Luca [8], Capone et al [9], Capone & Rionero [10], Carr [11], Chasnov & Tse [13], Hetsroni et al [19], Hill [20,21], Imamura et al [23], Kirillov et al [26], Krishnamurti [27], Kuznetsova & Sibgatullin [28], Larson [29,30], Machado et al [32], Mharzi et al [33], Papanicolaou et al [36], Prudhomme & Jasmin [37], Saravan & Nayaki [47], Shalbaf et al [49], Siddheshwar & Titus [51], Storesletten & Titus [52], Straughan [53,55,54,60,62], and Straughan & Walker [64]. Straughan [54], section 17.2, pp.…”

“…The subject of penetrative convection is one with immense application. For example, Straughan [54], chapter 17, discusses applications in geophysics, Krishnamurti [27], Larson [29,30] and Berlengiero et al [4] analyse applications in atmospheric physics, Mharzi et al [33] consider applications in building design, Tikhomolov [65] shows penetrative convection occurs in the Sun, Kaminski et al [25] show that penetrative convection may be responsible for assisting the rise of volcanic plumes into the Earth's atmosphere, Kirillov et al [26] discuss penetrative convection in the Laptev Sea coastal pycnocline layer, van den Berg et al [3] investigate the deep mantle of exosolar planets while Imamura et al [23] analyse penetration in clouds surrounding Venus, Machado et al [32] analyse penetrative convective clouds in connection with cloud to ground electrical discharges, and Prudhomme & Jasmin [37] study internal heat source convection when the heat source occurs in a porous biological material due to organic decay involving microbial activity.…”

Convection with Local Thermal Non-Equilibrium and Microfluidic Effects

“…In particular, the presence of a heat source or sink may give rise to the idea of penetrative convection where part of the layer has a tendency to move whereas the remainder of the layer will remain motionless until a certain point when movement in the rest of the layer "penetrates" into the stable layer and a resultant motion then ensues, cf. [48,180,181,191,216], and the references therein. [414], section 17.2, pp.…”

“…For example, [414], chapter 17, discusses applications in geophysics, [180,181] develop an application in solar pond design, [217,231,232] and [48] analyse applications in atmospheric physics, [289] consider applications in building design, [451] shows penetrative convection occurs in the Sun, [204] show that penetrative convection may be responsible for assisting the rise of volcanic plumes into the Earth's atmosphere, [216] discuss penetrative convection in the Laptev Sea coastal pycnocline layer, [465] investigate the deep mantle of exosolar planets while [191] analyse penetration in clouds surrounding Venus, [254] analyse penetrative convective clouds in connection with cloud to ground electrical discharges, and [353] study internal heat source convection when the heat source occurs in a porous biological material due to organic decay involving microbial activity.…”