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801.
Lynne D. Talley Pavel Tishchenko Vladimir Luchin Alexander Nedashkovskiy Sergey Sagalaev Dong-Jin Kang Mark Warner Dong-Ha Min 《Progress in Oceanography》2004,61(2-4):277
Hydrographic properties from CTD and discrete bottle sample profiles covering the Japan (East) Sea in summer, 1999, are presented in vertical sections, maps at standard depths, maps on isopycnal surfaces, and as property–property distributions. This data set covers most of the Sea with the exception of the western boundary region and northern Tatar Strait, and includes nutrients, pH, alkalinity, and chlorofluorocarbons, as well as the usual temperature, salinity, and oxygen observations. 相似文献
802.
Hotspots in ambient noise caused by ice-edge eddies in the Greenland and Barents Seas 总被引:1,自引:0,他引:1
Johannessen O.M. Sagen H. Sandven S. Stark K.V. 《Oceanic Engineering, IEEE Journal of》2003,28(2):212-228
Mesoscale eddies are frequently observed in the Greenland and Barents Seas' marginal ice zone (MIZ). The objective of this study was to investigate the hypothesis that acoustic hotspots along the ice-edge region are due to mesoscale eddy currents interacting with the broken-up ice floes in the MIZ. To test this hypothesis, ambient-noise case studies were carried out during the MIZEX 85-87 and SIZEX 89 field experiments. In each experiment, ice-edge eddies were localized visually from aircraft and by use of satellite remote-sensing data obtained in near real time. Sonobuoys were, thereafter, deployed by fix-wing aircraft and helicopters in selected eddy areas. Ambient-noise data, recorded over several hours by aircraft, were analyzed estimating averaged ambient-noise levels at four selected frequencies: 40, 100, 315, and 1000 Hz. The analysis showed high mean levels and large gradients in ambient noise near ice-edge eddies and during strong wind and wave forcing against the ice edge. The conclusion of this study is that mapping of the ice edge and localization of mesoscale ocean processes using remote sensing from space will provide important input to ambient-noise prediction in the MIZ. 相似文献
803.
This study presents the results of the decoupling of a free-roll decay test by wavelet transforms. A free-roll decay test was performed to determine the coefficients of damping terms in equations of motion. No motion of the model was restricted during the experiment. A slight yaw motion was found while the model was in the free-roll decay motion. It was necessary to extract a pure roll motion from the experimental data. Wavelet transforms were applied to the signals to extract the pure roll motion. The results were compared to those found through the Fourier transform. Discrete wavelet transforms were able to efficiently decouple the test signals, while the continuous wavelet transform and the Fourier transform could not. 相似文献
804.
The upper layer (above 140 m depth) temperature in the western Philippine Sea near Taiwan was sampled using a coastal monitoring
buoy (CMB) with 15 attached thermistors during July 28–August 7, 2005. The data were collected every 10 min at 1, 3, 5, 10,
15, and 20 m using the CMB sensors, and every 15 sec at 15 different depths between 25 m and 140 m. Internal waves and solitons
were identified from the time-depth plot of the temperature field. Without the internal waves and solitons, the power spectra,
structure functions, and singular measures (representing the intermittency) of temperature field satisfy the power law with
multi-scale characteristics at all depths. The internal waves do not change the basic characteristics of the multifractal
structure. However, the internal solitons change the power exponent of the power spectra drastically, especially in the low
wave number domain; they also break down the power law of the structure function and increase the intermittency parameter.
The physical mechanisms causing these different effects need to be explored further. 相似文献
805.
Effect of native and invasive cordgrass on Macoma petalum density, growth, and isotopic signatures 总被引:1,自引:0,他引:1
Ecosystem engineers can influence community and ecosystem dynamics by controlling resources, modifying the flow of energy or biomass, or changing physical characteristics of the habitat. Invasive hybrid cordgrass (Spartina alterniflora × Spartina foliosa) is an ecosystem engineer in salt marshes in San Francisco Bay, California, U.S.A. that raises intertidal elevations and may be either increasing C4 plant carbon input into food webs or tying up carbon in a form that is not usable by consumers. A manipulative experiment compared abundance, growth, and stable isotope (δ13C and δ15N) composition of the clam Macoma petalum (=M. balthica) among native marsh, hybrid Spartina, and mudflats in central San Francisco Bay. We found higher densities (individuals m−2) of M. petalum on mudflats compared to either native or hybrid Spartina (p < 0.001). Macoma petalum shell growth was significantly greater in mudflats than in either vegetation type in 2002 (p = 0.005) but not 2003. Differences in shell growth between native and hybrid Spartina were not significant. Stable isotope results showed differences between habitats in δ13C but not δ15N. Carbon signatures of M. petalum placed in Spartina were much more depleted than the isotopic signature of Spartina. Neither native nor hybrid Spartina appears to be a significant carbon source for M. petalum in San Francisco Bay, and we found no evidence that hybrid Spartina contributes carbon to M. petalum beyond what is provided by S. foliosa, despite the hybrid's much greater biomass. Our results show that loss of mudflat habitat, rather than increased input of C4 carbon, is the greatest effect of the invasion of hybrid Spartina on M. petalum. 相似文献
806.
807.
808.
We study the problem of determination of the sound field of a point harmonic source in the coastal zone and the influence of a cylindrical body floating above the source on the sound field formed in the marine medium. A numerical-analytic method is proposed for the determination of the velocity potential. According to this method, the unknown coefficients in the general solution of the problem are determined from the corresponding infinite system of linear algebraic equations by the method of reduction. We present results of numerical calculations for a special case of a waveguide whose parameters are typical of the coastal part of the sea and perform the comparative analysis of the data obtained as a result of variation of the indicated parameters. 相似文献
809.
R.N. Hey F. Martinez S. Diniega D.F. Naar J. Francheteau R. Armijo M. Constantin J.P. Cogné J. Girardeau R. Hekinian R. Searle 《Marine Geophysical Researches》2002,23(1):1-12
Several mechanisms have been proposed to account for the rotation of the nearly north-south abyssal hill fabric formed on the East Pacific Rise north of the Easter Microplate to the nearly east-west trends in the northern microplate interior. Proposed mechanisms include rigid microplate rotation, transform fault – parallel shear, and bookshelf faulting during the transfer of lithosphere from the Nazca Plate to the microplate. We used a submersible magnetometer on a NAUTILE dive program to measure the magnetic vector rotation of a pillow basalt and dike spur near Pito Deep, the present location of the tip of the propagating rift system that created the microplate. Our results, although too limited to draw strong conclusions from, suggest clockwise rotations of the seafloor magnetic vectors inconsistent with the transform-parallel shear model, and larger than can be explained solely by rigid microplate rotation. 相似文献
810.
Mesoscale features in the eastward extension of the Kuroshio were investigated using assimilation of TOPEX/POSEIDON (T/P)
data into a three-layer quasi-geostrophic model. The T/P data exhibited an elongated state of the southern recirculation gyre
in 1993–95 and 1997, between whose two periods the gyre had a contracted state in 1995–96. A few stationary eddies were located
in the southern gyre during the contracted state. The baroclinic instability, which was indicated by the phase shift from
the uppermost-to the lowest-layer anomalies toward the downstream side, was evident near the Kuroshio Extension (KE) path.
Since the instability never appeared in the artificial model without bottom topography, the topographic barrier for the eastward
flow in the lowest layer was a necessary condition for the instability. The instability synchronized with the transition in
the western region of the KE axis from the elongated to the contracted states. This evolution was interpreted as if the baroclinic
instability played some part in the KE states and was a trigger for the transition from the elongated to the contracted states. 相似文献