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Registros recuperados: 5
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Helium isotopes at the Rainbow hydrothermal site (Mid-Atlantic Ridge, 36 degrees 14 ' N) 5
Jean Baptiste, Philippe; Fourre, Elise; Charlou, Jean-luc; German, Christopher; Radford Knoery, Joel.
The He-3/He-4 ratio and helium concentration have been measured in the vent fluids and the dispersing plume of the Rainbow hydrothermal site, on the Mid-Atlantic Ridge (MAR). The He-3/He-4 ratio (7.51 R-a) and He-3 end-member concentration (25 pmol/kg) are in the range of observed values elsewhere on mid-ocean ridges, pointing to the relative homogeneity of the upper mantle with respect to helium isotope geochemistry. He-3 is linearly correlated with methane and manganese throughout the plume, with CH4/He-3 and Mn/He-3 ratios identical to those measured in the hot fluids. The bulk residence time of the plume in the rift valley estimated from the plume He-3 budget is similar to20 days. The He-3 flux transported by the plume, calculated from current-meter...
Tipo: Text Palavras-chave: Mid Atlantic Ridge; Heat flux; Isotopes; Hydrothermal vents; Helium.
Ano: 2004 URL: https://archimer.ifremer.fr/doc/2004/publication-772.pdf
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Convection regime between canopy and air in a greenhouse 63
Atarassi,Roberto Terumi; Folegatti,Marcos Vinicius; Brasil,René Porfírio Camponez do.
The use of covering materials in protected environments modifies the air movement close to the crop canopy compared to external environment, which changes the heat and mass transfer between canopy and air. Several researches have been made in greenhouses to estimate mass and heat flux using dimensionless numbers to characterize the type of convection (forced, free or mixed). The knowledge of which one is dominant allows simplifications and specific approaches. The dominant convection regime between canopy and air was determined in a naturally ventilated greenhouse cropped with sweet pepper. Forced convection was predominant, representing more than 70% of the time. During daytime, an increase of mixed convection was observed. It is thus appropriated the use...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Heat flux; Leaf; Aerodynamic resistance.
Ano: 2006 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162006000100012
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Hydrography and flow in the Lucky Strike segment of the Mid-Atlantic Ridge 5
Thurnherr, A. M.; Reverdin, G; Bouruet Aubertot, P; Laurent, L; Vangriesheim, Annick; Ballu, V.
The Lucky Strike segment between 37 and 38N on the Mid-Atlantic Ridge is the focus of the international MoMAR program to monitor seafloor-spreading processes. During the GRAVILUCK cruise in August 2006, hydrographic, velocity and light-scattering data were collected in the rift valley at Lucky Strike in order to investigate the regional dynamics and to provide background information for the monitoring effort. The survey observations reveal a remarkably simple dynamical setting dominated by persistent northward flow transporting approximate to 0.2 Sv of water along the rift valley. Approximately half of this transport must upwell within a deep basin that occupies the northern half of the segment. In the comparatively shallow segment center, the along-valley...
Tipo: Text Palavras-chave: Azores triple junction; Central north Atlantic; Hydrothermal vents; Particle flux; Rift valley; Heat flux; Water; Circulation; Currents; Fields.
Ano: 2008 URL: http://archimer.ifremer.fr/doc/2008/publication-4785.pdf
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Hydrothermal activity along the slow-spreading Lucky Strike ridge segment (Mid-Atlantic Ridge): Distribution, heatflux, and geological controls 5
Escartin, J.; Barreyre, T.; Cannat, M.; Garcia, R.; Gracias, N.; Deschamps, A.; Salocchi, A.; Sarradin, Pierre-marie; Ballu, V..
We have reviewed available visual information from the seafloor, and recently acquired microbathymetry for several traverses across the Lucky Strike segment, to evaluate the distribution of hydrothermal activity. We have identified a new on-axis site with diffuse flow, Ewan, and an active vent structure ∼1.2 km from the axis, Capelinhos. These sites are minor relative to the Main field, and our total heatflux estimate for all active sites (200–1200 MW) is only slightly higher than previously published estimates. We also identify fossil sites W of the main Lucky Strike field. A circular feature ∼200 m in diameter located on the flanks of a rifted off-axis central volcano is likely a large and inactive hydrothermal edifice, named Grunnus. We find no...
Tipo: Text Palavras-chave: Hydrothermalism; Mid-ocean ridge; Heat flux; Faulting; Oceanic crust; Mid-Atlantic Ridge.
Ano: 2015 URL: http://archimer.ifremer.fr/doc/00281/39241/37812.pdf
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Erosion of the nocturnal boundary layer in the central Amazon during the dry season 36
CARNEIRO,Rayonil Gomes; FISCH,Gilberto; BORGES,Camilla Kassar; HENKES,Alice.
ABSTRACT In this study, the erosion of the nocturnal boundary layer (NBL) was analyzed in the central Amazon during the dry season of 2014, using data from the GoAmazon 2014/5 Project and high-resolution model outputs (PArallelized Les Model - PALM). The dataset consisted of in situ (radiosonde) and remote sensing instruments measurements (Ceilometer, Lidar, Wind Profiler, microwave radiometer, and SODAR). The results showed that the NBL erosion occurred, on average, two hours after sunrise (06:00 local time), and the sensible heat flux provided more than 50% of the sensible heating necessary for the erosion process to occur. After the erosion, the convective phase developed quickly (175.2 m h-1). The measurements of the remote sensors showed that the...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Planetary boundary layer; Turbulent kinetic energy; Heat flux; NBL erosion.
Ano: 2020 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0044-59672020000100080
Registros recuperados: 5
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