Statistical Analysis of Tropical Disturbances over the South China Sea During 1997-2006     

WANG Lei  LAU Kai Hon 《中国海洋大学学报(英文版)》2011,10(2)

Tropical disturbances over the South China Sea (SCS) during the period of 1997-2006 are analyzed using the Tropical Storm and Hurricane WX products. A total of 158 tropical disturbances were formed over the SCS from 1997 to 2006, with 54 developing tropical disturbances which developed into tropical depressions and 104 non-developing tropical disturbances which never developed into tropical depressions. The development rate of tropical disturbances into tropical depressions was 34.18% in these ten years. During the period of this study, total annual numbers of tropical disturbances and developing tropical disturbances over the SCS had significant decreasing trends; however, the development rate of tropical disturbances had an insignificant increasing trend.  相似文献   

Statistical analysis of tropical disturbances over the South China Sea during 1997�C2006     

LAU Kai Hon 《中国海洋大学学报(英文版)》2011,10(2):99-105

Tropical disturbances over the South China Sea (SCS) during the period of 1997-2006 are analyzed using the Tropical Storm and Hurricane WX products. A total of 158 tropical disturbances were formed over the SCS from 1997 to 2006, with 54 de-veloping tropical disturbances which developed into tropical depressions and 104 non-developing tropical disturbances which never developed into tropical depressions. The development rate of tropical disturbances into tropical depressions was 34.18% in these ten years. During the period of this study, total annual numbers of tropical disturbances and developing tropical disturbances over the SCS had significant decreasing trends; however, the development rate of tropical disturbances had an insignificant increasing trend.  相似文献   

Overlapping spreading centres: 3-D inversion of the magnetic field at 9°03'N on the East Pacific Rise     

Jean-Christophe Sempere  Ken C. Macdonald  Stephen P. Miller 《Geophysical Journal International》1984,79(3):799-811

Summary. Overlapping spreading centres (OSCs) represent a new type of plate boundary interaction in which en échelon rise segments overlap significantly and are not joined by a transform fault.
A three-dimensional Fourier inversion of the magnetic field was performed on an overlapping spreading centre to remove the effects of topography and ridge orientation. A magnetic high exists at the tip of one of the two ridge segments. Forward modelling suggests that the anomalous magnetic field cannot be attributed to the effects of topography alone. The inversion reveals the existence of a magnetization high at the tip of the eastern spreading centre. Maximum magnetization values are consistent with ones obtained in other high amplitude zones in the Pacific as well as with the measured magnetization of samples dredged in the same areas. We suggest that the magnetization high over the eastern ridge tip of the 9°03'N OSC is associated with highly evolved basalts enriched in iron and titanium. Such enrichment may be caused by enhanced crystal fractionation within an axial magma chamber which is intermittent and occasionally freezes as the eastern spreading axis propagates into older lithosphere.  相似文献   

X-ray reflection in the nearby Seyfert 2 galaxy NGC 1068     

Ken Pounds  Simon Vaughan 《Monthly notices of the Royal Astronomical Society》2006,368(2):707-714

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Submarine prehistoric archaeology of the North Sea. Research priorities and collaboration with industry. CBA Research Report 141. N. C. Fleming (ed.). Council for British Archaeology,York, 2004 (150 pp.). ISBN: 1 902771 46 X     

Ken Thomson 《第四纪科学杂志》2006,21(4):418-418

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A web-based real-time and full-resolution data visualization for Himawari-8 satellite sensed images     

Ken T. Murata  Praphan Pavarangkoon  Atsushi Higuchi  Koichi Toyoshima  Kazunori Yamamoto  Kazuya Muranaga  Yoshiaki Nagaya  Yasushi Izumikawa  Eizen Kimura  Takamichi Mizuhara 《Earth Science Informatics》2018,11(2):217-237

It has been almost four decades since the first launch of geostationary meteorological satellite by Japan Meteorological Agency (JMA). The specifications of the geostationary meteorological satellites have shown tremendous progresses along with the generations, which are now entering their third generation. The third-generation geostationary meteorological satellites not only yield basic data for weather monitoring, but also globally observe the Earth’s environment. The development of multi-band imagers with improved spatial resolution onboard the third-generation geostationary meteorological satellites brings us meteorological data in larger size than those of the second-generation ones. Thus, new techniques for domestic and world-wide dissemination of the observational big data are needed. In this paper, we develop a web-based data visualization for Himawari-8 satellite sensed images in real time and with full resolution. This data visualization is supported by the ecosystems, which uses a tiled pyramid representation and parallel processing technique for terrain on an academic cloud system. We evaluate the performance of our techniques for domestic and international users on laboratory experiments. The results show that our data visualization is suitable for practical use on a temporal preview of observation image data for the domestic users.  相似文献   

A finite difference method for earthquake sequences in poroelastic solids     

Kim Torberntsson  Vidar Stiernström  Ken Mattsson  Eric M. Dunham 《Computational Geosciences》2018,22(5):1351-1370

Induced seismicity (earthquakes caused by injection or extraction of fluids in Earth’s subsurface) is a major, new hazard in the USA, the Netherlands, and other countries, with vast economic consequences if not properly managed. Addressing this problem requires development of predictive simulations of how fluid-saturated solids containing frictional faults respond to fluid injection/extraction. Here, we present a finite difference method for 2D linear poroelasticity with rate-and-state friction faults, accounting for spatially variable properties. Semi-discrete stability and accuracy are proven using the summation-by-parts, simultaneous-approximation-term (SBP-SAT) framework for discretization and boundary condition enforcement. Convergence rates are verified using the method of manufactured solutions and comparison to the analytical solution to Mandel’s problem. The method is then applied to study fault slip triggered by fluid injection and diffusion through high-permeability fault damage zones. We demonstrate that in response to the same, gradual forcing, fault slip can occur in either an unstable manner, as short-duration earthquakes that radiate seismic waves, or as stable, aseismic, slow slip that accumulates over much longer time scales. Finally, we use these simulation results to discuss the role of frictional and elastic properties in determining the stability and nature of slip.  相似文献   

The age of Earth’s largest volcano: Tamu Massif on Shatsky Rise (northwest Pacific Ocean)   总被引：1，自引：0，他引：1  

Jörg Geldmacher  Paul van den Bogaard  Ken Heydolph  Kaj Hoernle 《International Journal of Earth Sciences》2014,103(8):2351-2357

This study presents laser step-heating ⁴⁰Ar/³⁹Ar age determinations of basaltic lava samples from Tamu Massif, the oldest and largest edifice of the submarine Shatsky Rise in the northwest Pacific and Earth’s proposed largest volcano. The rocks were recovered during Integrated Ocean Drilling Program Expedition 324, which cored 160 m into the igneous basement near the summit of Tamu Massif. The analyzed lavas cover all three major stratigraphic groups penetrated at this site and confirm a Late Jurassic/Early Cretaceous age for the onset of Shatsky Rise volcanism. Lavas analyzed from the lower and middle section of the hole yield plateau ages between 144.4 ± 1.0 and 143.1 ± 3.3 Ma with overlapping analytical errors (2σ), whereas a sample from the uppermost lava group produced a significantly younger age of 133.9 ± 2.3 Ma suggesting a late or rejuvenated phase of volcanism. The new geochronological data infer minimum (average) melt production rates of 0.63–0.84 km³/a over a time interval of 3–4 million years consistent with the presence of a mantle plume.  相似文献   

Distribution of nitrous oxide dissolved in water masses in the eastern subtropical North Pacific and its origin inferred from isotopomer analysis     

Ayako Fujii  Sakae Toyoda  Osamu Yoshida  Shuichi Watanabe  Ken’ichi Sasaki  Naohiro Yoshida 《Journal of Oceanography》2013,69(2):147-157

N₂O concentration and its isotopomer ratios were measured over a wide area from San Diego to Honolulu in the eastern subtropical North Pacific (ESNP). Waters in the study area had an N₂O maximum (38.2–50.5 nmol kg^?1) at 600–1000 m depth, which is similar to the profiles obtained previously in other areas in the North Pacific. We separated the seawater into five water masses (two for the surface layer, two for the middle layer, and one for the deep layer) and deduced N₂O production–consumption mechanisms in each water body by use of N₂O isotopomer ratios. The results showed that the mechanisms differ slightly among water masses. In the “coastal” surface layer, N₂O is produced by nitrification (NH₂OH oxidation). In the “open ocean” surface layer, it is produced mainly by nitrifier denitrification and to a lesser extent by nitrification under substrate-limited conditions. In both “upwelling” and “open ocean” middle layers it is produced mainly by denitrification and to a lesser extent by nitrifier denitrification. It is also partly reduced. In the deep layer, it is produced predominantly by denitrification with partial reduction. In this way, isotopomers aid elucidation of production–consumption mechanisms of N₂O in the sea even though the mechanisms cannot always be ascertained.  相似文献   

Rapid shipboard identification and enumeration of pelagic marine fish eggs by a simple photographic technique (note)     

Robin C. Murdoch  Richard J. Singleton  Ken R. Grange 《新西兰海洋与淡水研究杂志》2013,47(1):137-140

A technique is described for obtaining rapid high‐quality silhouette photographs of plankton samples at sea. This technique was designed to facilitate identification and enumeration of pelagic marine fish eggs in near real‐time. It uses readily available photographic materials and unlike previously described techniques, the silhouettes are recorded directly on to photographic paper rather than film. The resolution is adequate for microscopic measurements. Examples are presented from a cruise off Westland, New Zealand, which investigated the distribution of hoki eggs.  相似文献