Candela
Julio
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Julio
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ArticleDominant circulation patterns of the deep Gulf of Mexico(American Meteorological Society, 2018-03-01) Perez-Brunius, Paula ; Furey, Heather H. ; Bower, Amy S. ; Hamilton, Peter ; Candela, Julio ; García-Carrillo, Paula ; Leben, RobertThe large-scale circulation of the bottom layer of the Gulf of Mexico is analyzed, with special attention to the historically least studied western basin. The analysis is based on 4 years of data collected by 158 subsurface floats parked at 1500 and 2500 m and is complemented with data collected by current meter moorings in the western basin during the same period. Three main circulation patterns stand out: a cyclonic boundary current, a cyclonic gyre in the abyssal plain, and the very high eddy kinetic energy observed in the eastern Gulf. The boundary current and the cyclonic gyre appear as distinct features, which interact in the western tip of the Yucatan shelf. The persistence and continuity of the boundary current is addressed. Although high variability is observed, the boundary flow serves as a pathway for water to travel around the western basin in approximately 2 years. An interesting discovery is the separation of the boundary current over the northwestern slope of the Yucatan shelf. The separation and retroflection of the along-slope current appears to be a persistent feature and is associated with anticyclonic eddies whose genesis mechanism remains to be understood. As the boundary flow separates, it feeds into the westward flow of the deep cyclonic gyre. The location of this gyre—named the Sigsbee Abyssal Gyre—coincides with closed geostrophic contours, so eddy–topography interaction via bottom form stresses may drive this mean flow. The contribution to the cyclonic vorticity of the gyre by modons traveling under Loop Current eddies is discussed.
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ArticleAssessment of numerical simulations of deep circulation and variability in the Gulf of Mexico using recent observations(American Meteorological Society, 2020-04-08) Morey, Steven L. ; Gopalakrishnan, Ganesh ; Pallás-Sanz, Enric ; Azevedo Correia De Souza, Joao Marcos ; Donohue, Kathleen A. ; Pérez-Brunius, Paula ; Dukhovskoy, Dmitry S. ; Chassignet, Eric P. ; Cornuelle, Bruce D. ; Bower, Amy S. ; Furey, Heather H. ; Hamilton, Peter ; Candela, JulioThree simulations of the circulation in the Gulf of Mexico (the “Gulf”) using different numerical general circulation models are compared with results of recent large-scale observational campaigns conducted throughout the deep (>1500 m) Gulf. Analyses of these observations have provided new understanding of large-scale mean circulation features and variability throughout the deep Gulf. Important features include cyclonic flow along the continental slope, deep cyclonic circulation in the western Gulf, a counterrotating pair of cells under the Loop Current region, and a cyclonic cell to the south of this pair. These dominant circulation features are represented in each of the ocean model simulations, although with some obvious differences. A striking difference between all the models and the observations is that the simulated deep eddy kinetic energy under the Loop Current region is generally less than one-half of that computed from observations. A multidecadal integration of one of these numerical simulations is used to evaluate the uncertainty of estimates of velocity statistics in the deep Gulf computed from limited-length (4 years) observational or model records. This analysis shows that the main deep circulation features identified from the observational studies appear to be robust and are not substantially impacted by variability on time scales longer than the observational records. Differences in strengths and structures of the circulation features are identified, however, and quantified through standard error analysis of the statistical estimates using the model solutions.
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Technical ReportCTD observations on the North Brazil shelf during A Multidisciplinary Amazon Shelf SEDiment Study (AMASSEDS) : November 1991(Woods Hole Oceanographic Institution, 1992-06) Limeburner, Richard ; Soares, Ivan Dias ; Candela, Julio ; Beardsley, Robert C.Hydrograhic (CTD) and acoustic Doppler current profiler (ADCP) observations were made on the North Brazil shelf adjacent to the mouth of the Amazon River during R/V Iselin cruise I9113 November 5-25, 1991 as part of A Multidisciplinary Amazon Shelf SEDiment Study (AMASSEDS). These observations were obtained during a large-scale survey on Leg 3 in support of geological and geochemical sampling, and during a frontal zone survey on Leg 4 consisting of 14 and 26 hourly CTD casts at anchored stations. The maximum sampling depth at each station was within two meters of the bottom. The primary objectives of the AMASSEDS hydrographic meaurement program were (a) to observe and characterize the temperature, salinity, density, oxygen, fluorescence and light transmission fields and their spatial variabilty on the north Brazilian shelf directly influenced by the Amazon River discharge, (b) to resolve the seaward extent and vertical structure of the surface plume of low salinity Amazon River water during different stages of river discharge, (c) to describe the spatial structure of the turbidity and associated suspended sediment distributions across the shelf, (d) to chacterize the properties of the Amazon shelf water beneath the surface plume and their seasonal variabilty, and (e) to describe the landward penetration of the North Brazil Current with respect to water properties and shelf currents. This report represents a summary in graphic and tabular form of the hydrograhic observations made during the fourth AMASSEDS cruise (I9113) on the R/V Iselin.