837 resultados para East Brookfield
Resumo:
A 120 m-long ice core was drilled in 2012 on the Derwael Ice Rise, coastal Dronning Maud Land, East Antarctica. Water stable isotopes (d18O and dD) stratigraphy is supplemented by discontinuous major ion profiles and continuous electrical conductivity measurements. The base of the ice core is dated to AD 1759 ± 16, providing a climate proxy for the past ~250 years. This data set presents the core's annual layer thickness history in meters water equivalent for the oldest age-depth estimate before correction for the influence of ice deformation.
Resumo:
The properties of snow on East Antarctic sea ice off Wilkes Land were examined during the Sea Ice Physics and Ecosystem Experiment (SIPEX) in late winter of 2007, focusing on the interaction with sea ice. This observation includes 11 transect lines for the measurement of ice thickness, freeboard, and snow depth, 50 snow pits on 13 ice floes, and diurnal variation of surface heat flux on three ice floes. The detailed profiling of topography along the transects and the d18O, salinity, and density datasets of snow made it possible to examine the snow-sea-ice interaction quantitatively for the first time in this area. In general, the snow displayed significant heterogeneity in types, thickness (mean: 0.14 +- 0.13 m), and density (325 +- 38 kg/m**3), as reported in other East Antarctic regions. High salinity was confined to the lowest 0.1 m. Salinity and d18O data within this layer revealed that saline water originated from the surface brine of sea ice in 20% of the total sites and from seawater in 80%. From the vertical profiles of snow density, bulk thermal conductivity of snow was estimated as 0.15 W/K/m on average, only half of the value used for numerical sea-ice models. Although the upward heat flux within snow estimated with this value was significantly lower than that within ice, it turned out that a higher value of thermal conductivity (0.3 to 0.4 W/K/m) is preferable for estimating ice growth amount in current numerical models. Diurnal measurements showed that upward conductive heat flux within the snow and net long-wave radiation at the surface seem to play important roles in the formation of snow ice from slush. The detailed surface topography allowed us to compare the air-ice drag coefficients of ice and snow surfaces under neutral conditions, and to examine the possibility of the retrieval of ice thickness distribution from satellite remote sensing. It was found that overall snow cover works to enhance the surface roughness of sea ice rather than moderate it, and increases the drag coefficient by about 10%. As for thickness retrieval, mean ice thickness had a higher correlation with ice surface roughness than mean freeboard or surface elevation, which indicates the potential usefulness of satellite L-band SAR in estimating the ice thickness distribution in the seasonal sea-ice zone.
Resumo:
Macrobenthos biomass and bottom biocoenoses were studied in the sublittoral zone of the southern East Siberian Sea. The macrobenthos is characterized by relatively high abundance (from 30 to 2680 #/m**2), biomass (from 0.25 to 578.8 g/m**2), and diversity (83 species in total). Lateral distribution of macrobenthos biomass correlates with a substrate type and salinity and is substantially higher in areas washed by the Arctic water mass than in estuaries with mixed fresh and Arctic waters and shows a tendency to decreasing in the convergence zone of different water masses. The highest macrobenthos biomass is observed in cores of water masses in the Long Strait area and in the eastern part of the sea.
Resumo:
Particulate matter concentration and water temperature at 5 m depth level are compared in the Canary upwelling region to the east of the Cape Blanc. It was found that accumulation of particulate matter was timed to hydrofrontal zones. Particle size distributions for particulate matter obtained using the Coulter counter agree with the hyperbolic law (of the Junge type) with double values for the size parameter, which changes for particle diameters of 5-6 microns. Average values for the size parameter in the region of the upwelling are significantly lower than in the open ocean. Specific surface of particulate matter associated with reactivity differs significantly on different sides of the upwelling front and increases beyond the upwelling.
Resumo:
Nine piston cores and six triggerweight cores retrieved from the eastern equatorial Pacific Ocean during the Venture 1 expedition were analyzed for dry-bulk density (DBD) and CaCO3 content. Sites are located along a north-south transect at 110°W from 11°N to 3°S and along an east-west transect from 110° to 90°W, at approximately 3°S. The data reveal two DBD-CaCO3 relationships and four patterns of CaCO3 abundance.
Resumo:
Acoustic estimates of herring and blue whiting abundance were obtained during the surveys using the Simrad ER60 scientific echosounder. The allocation of NASC-values to herring, blue whiting and other acoustic targets were based on the composition of the trawl catches and the appearance of echo recordings. To estimate the abundance, the allocated NASC -values were averaged for ICES-squares (0.5° latitude by 1° longitude). For each statistical square, the unit area density of fish (rA) in number per square nautical mile (N*nm-2) was calculated using standard equations (Foote et al., 1987; Toresen et al., 1998). To estimate the total abundance of fish, the unit area abundance for each statistical square was multiplied by the number of square nautical miles in each statistical square and then summed for all the statistical squares within defined subareas and over the total area. Biomass estimation was calculated by multiplying abundance in numbers by the average weight of the fish in each statistical square then summing all squares within defined subareas and over the total area. The Norwegian BEAM soft-ware (Totland and Godø 2001) was used to make estimates of total biomass.