Observations of the exchange of ocean waters between the Pacific Ocean and the Gulf of California
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Kinematics of seasonal exchanges of mass and heat between the Pacific Ocean and the Gulf of California are described. Results are based on 18 occupations between 1992 and 2013 of a hydrographic section across Pescadero Basin at the mouth of the Gulf and two and a half years (November 2003 to May 2006) of moored velocity and CTD measurements in 130 m of water on either side of the Pescadero Basin. Cyclonic conditions dominated in mid-winter and summer with inflow along Sinaloa and outflow along Baja California Sur (BCS). Advection of warm Gulf waters into the Pacific along BCS in late fall extended the warming along BCS by almost two months compared to Sinaloa; as a consequence, steric heights at BCS were higher, and resulted in near surface transport out of the Gulf of ~ 0.01 m s-1. During warming periods from May through November, coastal trapped waves transported heat into the Gulf along Sinaloa; the trapped wave motions along BCS were about a tenth of the amplitude of those at Sinaloa and contributed little to transport into the Pacific. Poleward monsoon winds were in phase with near-surface geostrophic flows into the Gulf which were about the same magnitude as out flow associated with much stronger equatorward wind. Next to BCS, higher salinity Gulf waters extended to 180 m depth (~26.2 kg m-3) and flow into the Pacific; these waters can be traced to subduction in the mid-Gulf region and, when they reach the Pacific, flow poleward in the undercurrent. If global warming intensifies the overturning Gulf circulation, lower oxygen and higher salinity waters may be advected northward along the continental shelf of North America.Keywords:
Outflow
Boundary current
Geostrophic current
Circulation (fluid dynamics)
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On the basis of CTD data obtained on 4 repeat-observed stations located at 121°E,19.5°N ~21°N in the Luzon Strait of the cruise in the summer of 2008,the role of disturbances caused by internal tides in temperature and salinity profiles in calculating of the geostrophic currents is discussed.The result shows that the role of disturbances caused by internal tides in temperature and salinity profiles in calculating of the geostrophic currents is significant.When we use hydrographic data to calculate the geostrophic currents we have to take measures to remove the disturbances caused by internal tides in temperature and salinity profiles,unless there would be great errors.By using the time-averaged CTD data,the geostrophic currents in the Luzon Strait is calculated.The result reveals that the significant part of the geostrophic currents appear above 350 m.Kuroshio intrusion mainly happens between 19.5°N and 21°N,especially at the upper layer.Between 19.5°N and 21°N,the water volume transport shows a in at upper and flowing out at deeper layer vertical structure,above 350 m the transport is westward(2.6 Sv) and below 350 m it is eastward(3.1 Sv).The distribution of the geostrophic currents we get is confirmed by the salinity distribution along 121°E Section.
Geostrophic current
Temperature salinity diagrams
Dynamic height
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Current measurements from three moored arrays on the Brazilian continental slope between 20°S and 28°S are investigated for the existence and strength of western boundary currents from near the surface down to the North Atlantic Deep Water. The Brazil Current is found to deepen southward from 100 m to more than 670 m and to strengthen its volume transport to 16.2 × 10 6 m 3 /s. Antarctic Intermediate Water is transported in a well‐developed boundary current southward at 28°S and northward north of Cabo Frio (24°S). This result supports earlier suggestions derived from the analysis of hydrographic data that Antarctic Intermediate Water enters the Brazil Basin from the east and bifurcates as it meets the continental break off Brazil. North Atlantic Deep Water is transported southward in a weakly developed boundary current that leads to lower estimates of volume transport than expected from earlier hydrographic data analysis.
Boundary current
Hydrographic survey
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The longest time series of CTD transects available in the Mallorca and Ibiza Channels (1996-2019) are presented. These hydrographic sections have a three-monthly periodicity and allow to resolve the seasonal cycle of water mass properties. Hydrographic sectionsThey are organized in two closed boxes also allowing the use of inverse models for the calculation of absolute geostrophic transports through the Channels. These use of long time series allows to establish the climatological distributions of potential temperature and salinity for each season of the year as well asand other relevant statistical properties such as the variance and covariance functions. TheOur results indicate that these distributions depart from normality makingand the median asis a better statistic than the mean value for the description of climatological fields. The salinity field shows a seasonal cycle in the upper layer indicating a higher influence of the Atlantic Water during summer, decreasing through the rest of the year. The Western Intermediate Water, which is mainlygenerally formed in the North-Western Mediterranean and the Balearic Sea, is observed preferentially in the Ibiza Channel during winter and spring. This water mass is better detected using a geometry-based method instead of the traditional criterion based on predefined temperature and salinity ranges. TheseBoth water masses flow preferentially southwards through the Ibiza Channel, and northwards through the Mallorca Channel, although intrusions in the opposite directions are observed. Below, tThe Levantine Intermediate Water shows a similar behaviour, but the mass transport analyses suggest that most of this water mass recirculates with the Balearic Current along the northern slope of the Islands with the Balearic Current. Although the depth of both Channels prevents the circulation of deep waters, a small fraction of the Western Mediterranean Deep Water could overflow the sills.
Balearic islands
Geostrophic current
Annual cycle
Temperature salinity diagrams
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Antarctic Intermediate Water
Circumpolar deep water
Temperature salinity diagrams
Deep ocean water
Anomaly (physics)
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Current meter
Gulf Stream
Geostrophic current
Hydrographic survey
Longitude
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This study describes the hydrography and water masses of the Santos Basin Continental Shelf (SBCS) during two hydrographic campaigns (SANAGU, SANSED) in 2019. Coastal Water (CW) is the dominant water mass in the southern portion of the SBCS, with relatively low salinity values (S<35.5 g kg–1), and satellite data show that local precipitation and river discharge could not account for the low salinity observed during the cruises in the southern region of the domain. The low salinity observed is explained by the transport from the south influenced by Subtropical Shelf Water (STSW), which was influenced by the La Plata River discharge. In the northern region of the SBCS, the South Atlantic Central Water (SACW) dominates the bottom layers of the water column, with the wind playing a major role in the uplift of this water mass, as evidenced by a wind impulse analysis. In this part of the shelf, Tropical Water (TW) was the second water mass in volume and occupied the surface layers and offshore the shelf. CW is restricted to a thin surface layer, which reaches distances of a few kilometers from the coast. Our analysis show the differences in the hydrographic structure of the SBCS and suggests that the SBCS can be divided in two regions with distinct characteristics: 1) the area southwest of São Sebastião, where the hydrographic parameters were modulated by the presence of the Subtropical Shelf Water (STSW); 2) the area northeast of São Sebastião, where the uplifting of SACW was the dominant process.
Temperature salinity diagrams
Hydrographic survey
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A review of available hydrographic data from the Faroe–Bank Channel indicates that North Icelandic/Arctic Intermediate water masses are present in the passage to a larger extent than was previously believed. The presently compiled statistics, including results on the seasonality, are discussed in relation to previous investigations. Finally, a high quality subset of the hydrographic data is used for an analysis of the alongchannel mixing of the intermediate water masses.
Icelandic
Hydrographic survey
Seasonality
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