Characteristics of Heat Transfer over the Ice Covered Sea of Okhotsk during Cold-air Outbreaks

Inoue, Jun; Ono, Jun; Tachibana, Yukio; Honda, Meiji; Iwamoto, Katsushi; Fujiyoshi, Yasushi; Takeuchi, Kensuke

doi:10.2151/jmsj.81.1057

Cited by 13 publications

(12 citation statements)

References 19 publications

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“…The positive trend of surface air temperature and precipitation is seen to be significant over the Okhotsk Sea, as is consistent with the results of the HEAT-T and WFLX-P experiments. It is noted that the maximum of the positive trend in air temperature over the central part of the Okhotsk Sea is partly related to the reduction in sea ice; this is evident because the sea ice cover acts as an insulator obstructing the heat fluxes between the ocean and atmosphere (Inoue et al 2003). The wind stress curl in March is also significantly strengthened and weakened in the Okhotsk Sea and the subarctic North Pacific, respectively (Fig.…”

Section: Atmospheric Forcing Pattern Related To the Trendmentioning

confidence: 94%

Causes of the Multidecadal-Scale Warming of the Intermediate Water in the Okhotsk Sea and Western Subarctic North Pacific

et al. 2015

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Causes of the multidecadal-scale warming of the intermediate water in the Okhotsk Sea and the western subarctic North Pacific during 1980-2008 are investigated using an ice-ocean coupled model with interannually varying atmospheric forcing. A hindcast experiment qualitatively reproduces the warming and decadal fluctuations of the intermediate water that are similar to those of observations: the warming is significant along the western part of the Okhotsk Sea and subarctic frontal region. The effects of the thermohaline-and wind-driven ocean circulation on the warming are evaluated from perturbation experiments on thermohaline (turbulent heat and freshwater fluxes) and wind causes, respectively. The thermohaline causes are shown to contribute positively to warming in the Okhotsk Sea Intermediate Water (OSIW). The heat budget analysis for the OSIW indicates that the warming is related to a decrease in cold and dense shelf water (DSW) flux, which is caused by a decrease in sea ice and surface water freshening. In contrast, the wind cause has a cooling effect in the OSIW through an increase in DSW. In the subarctic frontal region, the warming is mainly caused by the wind stress change. The heat budget analysis indicates that the warming is related to an increase in the northward advection of the subtropical warm water. These results imply that both thermohaline-and winddriven ocean circulation changes are essential components of the warming in the intermediate water. The atmospheric conditions responsible for the warming are related to a weakened Aleutian low and Siberian high in early and late winter.

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Section: Atmospheric Forcing Pattern Related To the Trendmentioning

confidence: 94%

Causes of the Multidecadal-Scale Warming of the Intermediate Water in the Okhotsk Sea and Western Subarctic North Pacific

et al. 2015

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“…Following Parkinson and Washington [1979] the total surface atmospheric heat flux was obtained from an estimate of the ice surface temperature assuming a balance between the atmospheric flux and the conductive heat flux through the ice. In this balance, the outgoing longwave radiation and the turbulent heat fluxes were linearized around the ice surface temperature, the turbulent fluxes being estimated from bulk formulae in which the heat transfer coefficient was chosen to be 1.3 3 10 23 [Inoue et al, 2003]. Fast ice is discriminated from thin ice using a criteria based on the 20 day averaged vertically polarized brightness temperature, TV 89 (see, e.g., the discussion in Tamura et al [2007]).…”

Section: Sea Ice and Atmospheric Datamentioning

confidence: 99%

Dense shelf water production in the Adélie Depression, East Antarctica, 2004–2012: Impact of the Mertz Glacier calving

et al. 2014

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Summer repeated hydrographic surveys and 4 years of mooring observations are used to characterize for the first time the interannual variability of the bottom water in the Mertz Glacier Polynya (MGP) on the East Antarctic shelf (142 E-146 E). Until 2010, large interannual variability was observed in the summer bottom salinity with year-to-year changes reaching 0.12 in Commonwealth Bay, the region with the highest sea ice production. The summer variability was shown to be linked to the efficiency of the convection during the preceding winter. The recent freshening of the bottom waters subsequent to the Mertz Glacier calving was well beyond the range of the precalving interannual variability. Within 2 years after the event, the bottom water of the shelf became too light to possibly contribute to renewal of the Antarctic Bottom Water. Rough estimates of the freshwater budget of the Ad elie Depression indicate that the freshening necessary to compensate for net sea ice production in the MGP did not change drastically after the Mertz calving. The year-to-year salinity changes appeared to respond to the MGP activity. Yet, prior to the calving, the convective system in the polynya was also partly controlled by the late winter bottom salinity through a mechanism leading to a sequence of alternatively fresher and more saline bottom waters over the period [2007][2008][2009][2010]. Exceptional events like the Mertz calving seem to be able to switch over the system into a less stratified state where convection responds more directly to changes in the surface forcing. IntroductionAntarctic Bottom Water (AABW), the densest water mass of the world ocean, occupies the abyssal layer of the Southern Ocean as a relatively well-oxygenated, cold and fresh product, which spreads north into the Atlantic, Indian, and Pacific oceans. Surface water transformation on the continental margins around Antarctica and subsequent sinking of the dense shelf waters along the slope supply the bottom limb of the ocean thermohaline circulation. It has been argued that changes in the properties or formation rate of the AABW could affect the strength of the thermohaline circulation, and therefore the global climate [Stouffer et al., 2007;Purkey and Johnson, 2012].The production of AABW is considered to originate on the Antarctic shelf in coastal polynyas where nearfreezing water (the so-called High-Salinity Shelf Water, HSSW) is formed through ocean surface cooling and brine drainage from growing sea ice. Upon mixing with ambient waters on the shelf and subsequent sinking and entrainment of Circumpolar Deep Water down the continental slope, these waters eventually acquire final AABW properties when reaching the abyssal layer of the Southern Ocean. While this process is suspected to occur at many locations around Antarctica, observations have unambiguously identified some primary formation sites: the Weddell Sea, the Ross Sea [Carmack, 1977], and the Ad elie-George V Land [Gordon and Tchernia, 1972;Rintoul, 1998]. Estimates of the relative im...

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“…Once sea ice is formed, its heat insulating effect greatly reduces the heat flux between the ocean and atmosphere. Iwamoto et al (2001) and Inoue et al (2003) estimated the surface heat flux in the southwestern part of the Okhotsk Sea from Rawinsonde observations under ice-covered conditions, and examined the heat insulating effect of sea ice. Inoue et al (2005) showed that heat fluxes over open water are two orders of magnitude greater than those over sea ice, based on direct measurement of turbulent heat flux over the sea ice region off Sakhalin Island by aircraft using eddy correlation methods.…”

Section: Introductionmentioning

confidence: 99%

“…Iwamoto et al (2001) and Inoue et al (2003) estimated the surface heat flux in the southwestern part of the Okhotsk Sea from Rawinsonde observations under ice-covered conditions, and examined the heat insulating effect of sea ice. Inoue et al (2005) showed that heat fluxes over open water are two orders of magnitude greater than those over sea ice, based on direct measurement of turbulent heat flux over the sea ice region off Sakhalin Island by aircraft using eddy correlation methods. Through the heat insulating effect of sea ice, the ice extent variability greatly changes the heat flux between the ocean and atmosphere, having the potential to influence the global scale atmospheric circulation.…”

Section: Introductionmentioning

confidence: 99%

Interannual Variability of Sea Ice Area in the Sea of Okhotsk: Importance of Surface Heat Flux in Fall

Ohshima

Nihashi

Hashiya

et al. 2006

Journal of the Meteorological Society of Japan

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We examine the interannual variability of the sea ice area in the Sea of Okhotsk in terms of surface heat flux, using highly resolved flux data with the ice concentration taken into account. On the northwest and east Sakhalin shelves, where the initial ice formation occurs, the onset of ice formation is simply determined by the local heat flux in fall (October-November); the degree to which the ocean is cooled by the atmosphere. Consequently, this heat flux mostly determines the interannual variability of sea ice area in the Okhotsk Sea in the initial stage. The air temperature anomaly is the main cause of the heat flux anomaly in fall. The fall heat flux has persistently affected the ice area anomaly, particularly until mid-January. In the later sea ice season, the relationship between the ice area and heat flux is obscured, particularly after mid-January, by the heat insulating effect of sea ice. The ice area variabilities in the southern and northeast regions are correlated with the local heat flux in the months preceding ice appearance, but not strongly. Our analysis suggests that the heat flux does not determine to what extent the ice advances finally in the Okhotsk Sea. Typical heat flux distributions in heavy and light ice years are also presented from our heat flux data: the heat loss center is located in the central Okhotsk Sea in light ice years, and moves to the eastern Okhotsk Sea near the Kuril Straits in heavy ice years.

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Characteristics of Heat Transfer over the Ice Covered Sea of Okhotsk during Cold-air Outbreaks

Cited by 13 publications

References 19 publications

Causes of the Multidecadal-Scale Warming of the Intermediate Water in the Okhotsk Sea and Western Subarctic North Pacific

Causes of the Multidecadal-Scale Warming of the Intermediate Water in the Okhotsk Sea and Western Subarctic North Pacific

Dense shelf water production in the Adélie Depression, East Antarctica, 2004–2012: Impact of the Mertz Glacier calving

Interannual Variability of Sea Ice Area in the Sea of Okhotsk: Importance of Surface Heat Flux in Fall

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