On the Subtropical Frontal Zone North of Hawaii During Winter

Roden, Gunnar I.

doi:10.1175/1520-0485(1980)010<0342:otsfzn>2.0.co;2

Cited by 68 publications

(61 citation statements)

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“…On smaller time and space scales density compensation is a well-known feature of the oceanic mixed layer, where vertical temperature and salinity gradients are negligible but horizontal gradients can be substantial, resulting from spatial differences in rainfall and solar heating. It is a common observation that patches of low salinity show a drop in temperature just large enough to cancel the density effect of the salinity (Roden 1980a). Temperature-salinity (TS) diagrams produced from thermosalinograph records often show the data aligned on constant density surfaces (Tomczak 1977).…”

Section: Discussionmentioning

confidence: 99%

Meridional Turner angles and density compensation in the upper ocean

Tippins

Tomczak

2003

Ocean Dynamics

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The World Ocean Atlas 1998 is used to determine the global field of the meridional density ratio R hy q ¼ aDT =bDS, where temperature and salinity changes DT and DS are evaluated along meridians, in and below the mixed layer. The focus of the analysis is the identification of regions where the R hy q field matches the values R q ¼ 2 sometimes suggested as the commonly perceived state of the ocean and R q ¼ 1, the condition of density compensation. Results are presented through fields of the meridional Turner angle Tu hy ¼ arctan(R hy q ) and through histograms of Tu hy for the Pacific, Atlantic and Indian Oceans at the ocean surface and at 300 m depth. At the 300-m depth level, which in the subtropics is representative of conditions in the permanent thermocline, the most frequently encountered values of the meridional density ratio are R hy q ¼ 3:2 in the North and South Pacific, R hy q ¼ 2:0 in the South Atlantic and Indian and R hy q ¼ 1:6 in the North Atlantic Ocean. Conditions in the mixed layer are more variable and show seasonal differences, but R hy q ¼ 2:0 occurs prominently in all ocean regions during winter and in all regions but the Atlantic during summer.

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Section: Discussionmentioning

confidence: 99%

Meridional Turner angles and density compensation in the upper ocean

Tippins

Tomczak

2003

Ocean Dynamics

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“…Evaporation exceeds precipitation by over one m yr −1 at ALOHA (da Silva et al, 1994). In order to maintain the salinity balance in the mixed layer at an approximate steady state, net transport of fresher waters from the south must occur by Ekman transport driven by the trade winds (Roden, 1980). The salinity maximum at ∼100 m represents the core of North Pacific Central Water Profiles with obvious diurnal mixed layers or density inversions at the surface were excluded from the average.…”

Section: Datamentioning

confidence: 99%

Constraining bubble dynamics and mixing with dissolved gases: Implications for productivity measurements by oxygen mass balance

Hamme¹,

Emerson²

2006

J Mar Res

124

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We used a dynamic mixed layer model to determine carbon export by the oxygen mass balance method from a time series of O 2 /Ar, N 2 /Ar and Ne measurements collected at station ALOHA near Hawaii from July 2000 to June 2001. The inert gas measurements constrain the flux of oxygen into the mixed layer from small, collapsing bubbles (injection) to be greater than or equal to the flux from larger bubbles (exchange), with mean estimates of the ratio in the range of 1-2. We also show that monthly observations of temperature and inert gases cannot constrain the rate of diapycnal mixing at this location, because of uncertainties in air-sea heat flux estimates and bubble dynamics. Organic carbon export from the mixed layer calculated from our dataset was 1.1 ± 0.5 mol C m −2 yr −1 , with most of the error deriving from uncertainties in the parameterization of diffusive gas exchange with wind speed. Our estimates of carbon export from the zone beneath the mixed layer but still in the euphotic zone ranged from 0 to 0.6 mol C m −2 yr −1 as the rate of background diapycnal mixing was increased from 0.1 to 1.0 cm 2 s −1 . We conclude that the oxygen mass balance method has errors of about a factor of two in areas similar to the subtropical North Pacific, with the main uncertainties deriving from mixing rates and the parameterization of diffusive gas exchange.

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“…In the western North Pacific, the STF is accompanied by a shallow eastward current, referred to as the Subtropical Countercurrent (STCC) [Yoshida and Kidokoro, 1967], suggesting a thermal wind relation between the STF and the STCC [Takeuchi, 1984]. The STF is also found in the eastern North Pacific, east of Hawaii, where it is identified as a temperature/salinity front during winter and a salinity front during summer [Roden, 1974[Roden, , 1975[Roden, , 1980Van Woert, 1982;Niiler and Reynolds, 1984;Lynn, 1986;Kazmin and Rienecker, 1996;Dinniman and Rienecker, 1999]. However the dynamics of the eastern STF could be very different from the STF in the western North Pacific, given that the STF forms the northern boundary of the eastern Pacific gyre [Sverdrup et al, 1942;Munk, 1950;Kenyon, 1975].…”

Section: Introductionmentioning

confidence: 99%

Decadal variability of the Subtropical Front of the western North Pacific in an eddy‐resolving ocean general circulation model

Yamanaka¹,

Ishizaki²,

Hirabara³

et al. 2008

J. Geophys. Res.

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[1] We examined decadal variability of the Subtropical Front (STF) of the western North Pacific by using a North Pacific ocean general circulation model (OGCM), comparing the results of three simulations with different horizontal resolutions. In the long-term mean fields, the eddy-resolving model (10 km) was able to simulate the distributions of the STF and the associated Subtropical Countercurrent (STCC) between 20°N and 30°N better than either the non-eddy-resolving model (100 km) or the eddy-permitting model (20 km) because it simulated the Kuroshio recirculation gyre more realistically. The simulated STF intensity exhibited significant decadal-scale variations: it was stronger in the late 1970s and weaker in the early 1990s. During these two periods, the simulated mode waters showed corresponding differences in their potential vorticity minima density and paths. We also investigated the relationship between the decadal-scale STF variability and atmospheric forcing. The results suggest that the decadal-scale STF variability can be largely explained by changes in the mode waters formed in the western North Pacific and advected to north of the STF by the subtropical gyre in response to a change in surface westerly winds that occurred in the mid-1970s.

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On the Subtropical Frontal Zone North of Hawaii During Winter

Cited by 68 publications

References 0 publications

Meridional Turner angles and density compensation in the upper ocean

Meridional Turner angles and density compensation in the upper ocean

Constraining bubble dynamics and mixing with dissolved gases: Implications for productivity measurements by oxygen mass balance

Decadal variability of the Subtropical Front of the western North Pacific in an eddy‐resolving ocean general circulation model

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