scholarly journals Water masses labeled with global fallout137Cs formed by subduction in the North Pacific

2008 ◽  
Vol 35 (1) ◽  
Author(s):  
Michio Aoyama ◽  
Katsumi Hirose ◽  
Kazuhiro Nemoto ◽  
Yasushi Takatsuki ◽  
Daisuke Tsumune
Keyword(s):  
North Pacific ◽  
Water Masses ◽  
The North ◽  
The North Pacific

scholarly journals Distributions of mixed layer properties in North Pacific water mass formation areas: comparison of Argo floats and World Ocean Atlas 2001

Ocean Science ◽  
2006 ◽  
Vol 2 (1) ◽  
pp. 61-70 ◽  
Author(s):  
F. M. Bingham ◽  
T. Suga
Keyword(s):  
Mixed Layer ◽  
North Pacific ◽  
World Ocean ◽  
Water Masses ◽  
Mode Water ◽  
The North ◽  
Central Mode Water ◽  
Central Mode ◽  
World Ocean Atlas ◽  
The North Pacific

Abstract. Winter mixed layer characteristics in the North Pacific Ocean are examined and compared between Argo floats in 2006 and the World Ocean Atlas 2001 (WOA01) climatology for a series of named water masses, North Pacific Tropical Water (NPTW), Eastern Subtropical Mode Water (ESTMW), North Pacific Subtropical Mode Water (NPSTMW), Light Central Mode Water (LCMW) and Dense Central Mode Water (DCMW). The WOA01 is found to be in good agreement with the Argo data in terms of water mass volumes, average temperature-salinity (T-S) properties, and outcrop areas. The exception to this conclusion is for the central mode waters, DCMW and LCMW, whose outcropping is shown to be much more intermittent than is apparent in the WOA01 and whose T-S properties vary from what is shown in the WOA01. Distributions of mixed layer T-S properties measured by floats are examined within the outcropping areas defined by the WOA01 and show some shifting of T-S characteristics within the confines of the named water masses. In 2006, all the water masses were warmer than climatology on average, with a magnitude of about 0.5°C. The NPTW, NPSTMW and LCMW were saltier than climatology and the ESTMW and DCMW fresher, with magnitudes of about 0.05. In order to put these results into context, differences between Argo and WOA01 were examined over the North Pacific between 20 and 45° N. A large-scsale warming and freshening is seen throughout this area, except for the western North Pacific, where results were more mixed.

scholarly journals Sensitivity of the Simulated Distributions of Water Masses, CFCs, and Bomb 14C to Parameterizations of Mesoscale Tracer Transports in a Model of the North Pacific

2006 ◽  
Vol 36 (3) ◽  
pp. 273-285 ◽  
Author(s):  
Yongfu Xu ◽  
Shigeaki Aoki ◽  
Koh Harada
Keyword(s):  
North Pacific ◽  
General Circulation ◽  
Western North Pacific ◽  
North Pacific Ocean ◽  
Circulation Model ◽  
Water Masses ◽  
Intermediate Water ◽  
North Pacific Intermediate Water ◽  
The North ◽  
The North Pacific

Abstract A basinwide ocean general circulation model of the North Pacific Ocean is used to study the sensitivity of the simulated distributions of water masses, chlorofluorocarbons (CFCs), and bomb carbon-14 isotope (14C) to parameterizations of mesoscale tracer transports. Five simulations are conducted, including a run with the traditional horizontal mixing scheme and four runs with the isopycnal transport parameterization of Gent and McWilliams (GM). The four GM runs use different values of isopycnal and skew diffusivities. Simulated results show that the GM mixing scheme can help to form North Pacific Intermediate Water (NPIW). Greater isopycnal diffusivity enhances formation of NPIW. Although greater skew diffusivity can also generate NPIW, it makes the subsurface too fresh. Results from simulations of CFC uptake show that greater isopycnal diffusivity generates the best results relative to observations in the western North Pacific. The model generally underestimates the inventories of CFCs in the western North Pacific. The results from simulations of bomb 14C reproduce some observed features. Greater isopycnal diffusivity generates a longitudinal gradient of the inventory of bomb 14C from west to east, whereas greater skew diffusivity makes it reversed. It is considered that the ratio of isopycnal diffusivity to skew diffusivity is important. An increase in isopycnal diffusivity increases storage of passive tracers in the subtropical gyre.

Water Masses in the Pacific in CCSM3

2008 ◽  
Vol 21 (17) ◽  
pp. 4514-4528 ◽  
Author(s):  
Lu Anne Thompson ◽  
Wei Cheng
Keyword(s):  
North Pacific ◽  
Coupled Model ◽  
Ocean Model ◽  
Water Masses ◽  
Convergence Zone ◽  
Intermediate Water ◽  
Atmospheric Component ◽  
The North ◽  
Ocean Models ◽  
The North Pacific

Abstract An examination of model water masses in the North Pacific Ocean is performed in the Community Climate System version 3 (CCSM3) and its ocean-only counterpart. While the surface properties of the ocean are well represented in both simulations, biases in thermocline and intermediate-water masses exist that point to errors in both ocean model physics and the atmospheric component of the coupled model. The lack of North Pacific Intermediate Water (NPIW) in both simulations as well as the overexpression of a too-fresh Antarctic Intermediate Water (AAIW) is indicative of ocean model deficiencies. These properties reflect the difficulty of low-resolution ocean models to represent processes that control deep-water formation both in the Southern Ocean and in the Okhotsk Sea. In addition, as is typical of low-resolution ocean models, errors in the position of the Kuroshio, the North Pacific subtropical gyre western boundary current (WBC), impact the formation of the water masses that form the bulk of the thermocline as well as the properties of the NPIW. Biases that arise only in the coupled simulation include too-salty surface water in the subtropical North Pacific and too deep a thermocline, the source of which is the too-strong westerlies at midlatitudes. Biases in the location of the intertropical convergence zone (ITCZ) and the southern Pacific convergence zone (SPCZ) lead to the opposite hemispheric asymmetry in water mass structure when compared to observations. The atmospheric component of the coupled model acts to compound most ocean model biases.

Regeneration of a warm anticyclonic ring by cold water masses within the western subarctic gyre of the North Pacific

2014 ◽  
Vol 70 (3) ◽  
pp. 211-223 ◽  
Author(s):  
Sachihiko Itoh ◽  
Ichiro Yasuda ◽  
Hiromichi Ueno ◽  
Toshio Suga ◽  
Shigeho Kakehi
Keyword(s):  
North Pacific ◽  
Cold Water ◽  
Water Masses ◽  
The North ◽  
Western Subarctic Gyre ◽  
The North Pacific

Pleistocene shifts of the Subarctic Front in the North Pacific: Evidence from planktonic foraminiferal proxy data

2020 ◽  
Author(s):  
Lara Jacobi ◽  
Dirk Nürnberg ◽  
Weng-si Chao ◽  
Ralf Tiedemann ◽  
Lester Lembke- Jene ◽  
...  
Keyword(s):  
Surface Water ◽  
North Pacific ◽  
Kuroshio Current ◽  
Water Masses ◽  
Subsurface Water ◽  
The North ◽  
Tropical Water ◽  
Subarctic Front ◽  
Pleistocene Climate ◽  
The North Pacific

<p>The North Pacific plays a key role in shaping the Earth’s climate, yet there still is a lack in understanding the complex interplay of atmosphere and ocean, and their respective circulation patterns reacting to a varying Pleistocene climate. Proxy records established on marine sediment core SO264-28-2, recovered from the Emperor Seamount Chain (Suiko Seamount; ~45°N, close to the Subarctic Front) during R/V SONNE Cruise SO264 in 2018, allow to reconstruct changes of surface and subsurface water masses in order to provide unique insight in spatial and temporal shifts of North Pacific Subarctic<em> vs.</em> Subtropical gyres. According to the preliminary age model based on radiocarbon dating, benthic oxygen isotopes, combined magneto-, tephra- and biostratigraphical approaches, the only 7 m long core covers the last ~1.35 Myr. This core was chosen due to its highly characteristic pattern in magnetic susceptibility and a prominent lithological change from carbonate oozes to more siliciclastic sediment sequences at ~1.2 Ma. Thus, numerous other cores from the study area can be correlated with it suggesting this core as a reference record for the North Pacific.</p><p>A continuous and synchronous cooling of both surface and subsurface ocean temperatures since ~1.35 Ma changed rapidly at 1.2 Ma to a continuous warming surface from <4 °C to ~ 8 °C while subsurface temperature remained constant below 4 °C. The long-term diverging temperatures and increasing salinities at both surface and subsurface point to the continuous northward displacement of the Subarctic Front and an increased influence of the North Pacific Tropical Water at Suiko Seamount, with most prominent, millennial-scale, changes of the gyre system and the related Kuroshio Current during interglacials. Around ~430 ka, the influence of warm and saline subtropical surface water masses declines, reflected by a rapid decrease of sea surface temperatures of 4-5 °C and a salinity inversion, whereby the subsurface water mass becomes more saline than the surface water. After ~430 ka, interglacials are very pronounced and with the prominent presence of low saline and cooler surface waters, conditions are similar to present.</p>

scholarly journals The Transition Region Mode Water of the North Pacific and Its Rapid Modification

2011 ◽  
Vol 41 (9) ◽  
pp. 1639-1658 ◽  
Author(s):  
Hiroko Saito ◽  
Toshio Suga ◽  
Kimio Hanawa ◽  
Nobuyuki Shikama
Keyword(s):  
Transition Region ◽  
Mixed Layer ◽  
North Pacific ◽  
Water Masses ◽  
Mode Water ◽  
Formation Region ◽  
Argo Float ◽  
The North ◽  
Modification Process ◽  
The North Pacific

Abstract Using Argo float data, this study examined the formation region, spatial distribution, and modification of transition region mode water (TRMW), which is a recently identified pycnostad in the subtropical–subarctic transition region of the North Pacific, the basin-scale boundary region between subtropical and subarctic water masses. Analyses of the formation fields of water masses within and around the transition region reveal that TRMW forms in a wide area from the western to central transition region and is separated from the denser variety of central mode water (D-CMW) to the south by a temperature and salinity front. TRMW has temperatures of 4°–9°C and salinities of 33.3–34.0, making it colder and fresher than D-CMW. TRMW has a density range of 26.3–26.6 σθ, and thick TRMW is widely distributed in the transition region. However, the range of the T–S properties at TRMW cores is substantially reduced downstream within 10°–20° longitude from the formation region by gradually losing its fresh and cold side. It is also demonstrated that a major part of TRMW of 26.4–26.6 σθ is entrained into the mixed layer in the following winter. Quasi-Lagrangian observation by an isopycnal-following Argo float demonstrates that the double-diffusive salt-finger convection plausibly causes not only rapid erosion of the TRMW pycnostads but also an increase of salinity and temperature at the TRMW cores, at least to some degree. It is demonstrated that strong salt fingering within TRMW is probably caused by geostrophic currents with vertical shear crossing the density-compensating T–S front that brings warm and saline water to the upper TRMW and creates instability in the salinity stratification. This modification process could explain why water that is subducted from the transition region and constitutes the pycnocline of the subtropical gyre in the North Pacific has different T–S properties from the winter mixed layer of the transition region. This knowledge about the modification process of subducted water in the transition region would help to model the permanent pycnocline structure more realistically and to clarify how large signals of decadal and multidecadal variability of sea surface temperature in this region are propagated into the ocean interior.

Re-evaluation of turbulent mixing vertical structure in the Bussol’ Strait and its impact on water masses in the Okhotsk Sea and the North Pacific

2014 ◽  
Vol 126 ◽  
pp. 121-134 ◽  
Author(s):  
Masahiro Yagi ◽  
Ichiro Yasuda ◽  
Takahiro Tanaka ◽  
Yuki Tanaka ◽  
Kazuya Ono ◽  
...  
Keyword(s):  
Turbulent Mixing ◽  
North Pacific ◽  
Vertical Structure ◽  
Water Masses ◽  
Okhotsk Sea ◽  
The North ◽  
The North Pacific

scholarly journals Water Masses Characteristics at the Western Pasific Equator on August 2018

2020 ◽  
Vol 4 (1) ◽  
pp. 43
Author(s):  
Duaitd Kolibongso
Keyword(s):  
Papua New Guinea ◽  
North Pacific ◽  
South Pacific ◽  
New Guinea ◽  
Water Masses ◽  
Coastal Current ◽  
Intermediate Water ◽  
Northern Coast ◽  
The North ◽  
The North Pacific

The Western Pacific Equator waters are a meeting place for water masses coming from the Northern and Southern Hemispheres. This study aims to identify the characteristics of water masses formed in the waters of Northern Papua. The study of water mass characteristics in the northern waters of Papua was carried out based on reanalysis data from the World Ocean Atlas (WOA) in August 2018. There were 12 stations divided into 3 transects to be analyzed in this study, namely transect 1 and transect 2 which stretched north-south and transect 3 which stretches east-west. The analysis were performed by method of the core layer and was processed with Sofware Ocean Data View (ODV). The results showed in the waters of North Papua there was a meeting of 2 water masses from the North Pacific and South Pacific. The water masses characteristics in latitudes <5 oLU are affected by surface and intermediates of the South Pacific carried by the Papua New Guinea Coastal Current that flows along the northern coast of Papua New Guinea and into Papua waters and beyond into the waters of the Halmahera Sea. Whereas the mass of water in latitudes > 5 oLU is dominated by surface and intermediate water masses from the North Pacific carried by North Equatorial Counter Current.

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