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261.
A.J. Jamieson T. Fujii M. Solan A.K. Matsumoto P.M. Bagley I.G. Priede 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(4):641-647
Since the first major hadal sampling efforts in the 1950s, crustaceans of the order Decapoda have been thought absent from the hadal zone (6000–11,000 m) with no representatives documented >5700 m. A baited video lander deployed at 6007, 6890 and 7966 m in the Kermadec Trench, 8798 and 9729 m in the Tonga Trench (SW Pacific), 6945 and 7703 m in the Japan Trench and 5469 m in the Marianas region (NW Pacific) has now revealed a conspicuous presence of the Benthesicymid prawn Benthesicymus crenatus Bate 1881. Decapods were observed at all sites except at 7966 m in the Kermadec Trench and the two Tonga Trench sites, making the deepest finding 7703 m in the Japan Trench, 2000 m deeper than previously thought. These natantian decapods were readily attracted to fish bait and, rather than feeding on the bait itself, were observed preying upon smaller scavenging amphipods. These are the first observations of predation in the hadal zone. In less than 10 h of bottom time, 12 observations of 10 individuals were documented at 6007 m and 5 observations of 3 individuals were documented at 6890 m in the Kermadec Trench. In the Japan Trench at 6945 m 29 observations of 20 individuals were documented whilst only one individual was seen at 7703 m. Two individuals were observed in the abyssal Marianas Region (5575 m). Also, in the Kermadec Trench, individual caridean prawns (Acanthephyra spp.) were observed at 6007 and 6890 m, proving categorically that the crustacean order of Decapoda is represented in the hadal zone. 相似文献
262.
Hajime Kawakami Makio C. Honda Kazuhiko Matsumoto Tetsuichi Fujiki Shuichi Watanabe 《Journal of Oceanography》2010,66(1):71-83
Observations of primary productivity, 234Th, and particulate organic carbon (POC) were made from west to east across the northern North Pacific Ocean (from station
K2 to Ocean Station Papa) during September–October 2005. Primary productivities in this region varied longitudinally from
approximately 236 to 444 mgC m−2d−1 and clearly indicate the West High East Low (WHEL) trend. We estimated east-west variations in the POC flux from the surface
layer (0–100 m) by using 234Th as a tracer. POC fluxes in the western region (44–53 mgC m−2d−1) were higher than those in the eastern region (21–34 mgC m−2d−1). However, the export ratios (e-ratios) ranged from approximately 8% to 16% and did not show the WHEL trend. Contrary to our expectation, no relation between
POC flux (or e-ratio) and diatom biomass (or dominance) was apparent in autumn in the northern North Pacific. 相似文献
263.
264.
Ocean Tide Models Developed by Assimilating TOPEX/POSEIDON Altimeter Data into Hydrodynamical Model: A Global Model and a Regional Model around Japan 总被引:36,自引:0,他引:36
A global ocean tide model (NAO.99b model) representing major 16 constituents with a spatial resolution of 0.5° has been estimated by assimilating about 5 years of TOPEX/POSEIDON altimeter data into barotropic hydrodynamical model. The new solution is characterized by reduced errors in shallow waters compared to the other two models recently developed; CSR4.0 model (improved version of Eanes and Bettadpur, 1994) and GOT99.2b model (Ray, 1999), which are demonstrated in comparison with tide gauge data and collinear residual reduction test. This property mainly benefits from fine-scale along-track tidal analysis of TOPEX/POSEIDON data. A high-resolution (1/12°) regional ocean tide model around Japan (NAO.99Jb model) by assimilating both TOPEX/POSEIDON data and 219 coastal tide gauge data is also developed. A comparison with 80 independent coastal tide gauge data shows the better performance of NAO.99Jb model in the coastal region compared with the other global models. Tidal dissipation around Japan has been investigated for M2 and K1 constituents by using NAO.99Jb model. The result suggests that the tidal energy is mainly dissipated by bottom friction in localized area in shallow seas; the M2 ocean tidal energy is mainly dissipated in the Yellow Sea and the East China Sea at the mean rate of 155 GW, while the K1 energy is mainly dissipated in the Sea of Okhotsk at the mean rate of 89 GW. TOPEX/POSEIDON data, however, detects broadly distributed surface manifestation of M2 internal tide, which observationally suggests that the tidal energy is also dissipated by the energy conversion into baroclinic tide. 相似文献
265.
266.
Abstract: Fluid inclusions in hydrothermal quartz and anhydrite samples from the Mori geothermal field, southwest Hokkaido, have been studied microthermometrically using heating/freezing stages. Based on homogenization temperatures of fluid inclusions, salinities after correction of effect of freezing-point depression of CO2 on ice melting temperatures of fluid inclusions, and previous geochemical data by Yoshida (1991), we discuss the geneses of various types of inclusion fluids in the Mori geothermal reservoir. 相似文献
267.
268.
Ryo Yamazaki Kazunori Kohri Aya Bamba Tatsuo Yoshida Toru Tsuribe Fumio Takahara 《Monthly notices of the Royal Astronomical Society》2006,371(4):1975-1982
We study the emission from an old supernova remnant (SNR) with an age of around 105 yr and that from a giant molecular cloud (GMC) encountered by the SNR. When the SNR age is around 105 yr, proton acceleration is efficient enough to emit TeV γ-rays both at the shock of the SNR and that in the GMC. The maximum energy of primarily accelerated electrons is so small that TeV γ-rays and X-rays are dominated by hadronic processes, π0 -decay and synchrotron radiation from secondary electrons, respectively. However, if the SNR is older than several 105 yr, there are few high-energy particles emitting TeV γ-rays because of the energy-loss effect and/or the wave-damping effect occurring at low-velocity isothermal shocks. For old SNRs or SNR–GMC interacting systems capable of generating TeV γ-ray emitting particles, we calculated the ratio of TeV γ-ray (1–10 TeV) to X-ray (2–10 keV) energy flux and found that it can be more than ∼102 . Such a source showing large flux ratio may be a possible origin of recently discovered unidentified TeV sources. 相似文献
269.
The dispersion of SeaMARC II phase-difference samples is discussed. They appear to be a function of signal direction, range, noise level, and backscatter strength of the bottom. Field data from a lava flow area and from sedimented areas at different depths are compared. The temporal distribution of the phase-difference samples was skewed and asymmetrical about the model. The angular distribution was symmetrical about the mode, with some phase wrap-around. The field data show the presence of a complicated noise interference field. The amount of phase-difference dispersion was larger than that calculated by using a simple Gaussian isotropic noise model, possibly suggesting an additional phase-dispersion process caused by bottom roughness. The method used to produce bathymetry data from the phase-difference samples was evaluated in light of the phase-difference sample distribution 相似文献
270.