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41.
Establishment of numerical beach-litter hindcast/forecast models: an application to Goto Islands, Japan 总被引:1,自引:0,他引:1
This study attempts to establish a system for hindcasting/forecasting the quantity of litter reaching a beach using an ocean circulation model, a two-way particle tracking model (PTM) to find litter sources, and an inverse method to compute litter outflows at each source. Twelve actual beach survey results, and satellite and forecasted wind data were also used. The quantity of beach litter was hindcasted/forecasted using a forward in-time PTM with the surface currents computed in the ocean circulation model driven by satellite-derived/forecasted wind data. Outflows obtained using the inverse method was given for each source in the model. The time series of the hindcasted/forecasted quantity of beach litter were found consistent with the quantity of beach litter determined from sequential webcam images of the actual beach. The accuracy of the model, however, is reduced drastically by intense winds such as typhoons which disturb drifting litter motion. 相似文献
42.
藏北高原地区干、雨季大气边界层结构的不同特征 总被引:6,自引:2,他引:4
利用2004年4月预试验期(PIOP)和8月加强期(IOP)的无线电探空仪观测资料,分析了藏北高原地区干、雨季大气边界层结构的不同特征.结果显示:藏北高原地区边界层虚位温、比湿等日变化大,对流混合层高度较高,高度干季在2 211~4 430 m之间,雨季在1 006~2 212 m之间,干季的对流混合层高度明显高于雨季... 相似文献
43.
Shigeru Mizugaki Yuichi Onda Taijiro Fukuyama Satoko Koga Hiroki Asai Shinya Hiramatsu 《水文研究》2008,22(23):4519-4531
To analyse suspended sediment sources in unmanaged Japanese cypress plantation watersheds, field measurements and fingerprinting of the suspended sediment was conducted in the Shimanto River basin in southern Japan. For sediment fingerprinting, 137Cs and 210Pbex were detected by means of gamma‐ray spectrometry in the surface soil of the forest floor, stream bank and truck trail and mobilized sediment by interrill erosion. The 137Cs and 210Pbex activities associated with the forest floor materials were considerably higher than those of the stream bank and truck trail. The 137Cs and 210Pbex activities associated with the suspended sediment were found to vary with the sampling period. Evidently, the suspended sediment can comprise materials generated from the forest floor by interrill erosion and those from the truck trail and/or stream bank. The multivariate sediment‐mixing model using 137Cs and 210Pbex showed that the contribution of the forest floor varied periodically, ranging from 23–56% in the Hinoki 156 subwatershed and from 18–85% in the Hinoki 155 subwatershed. The difference in the average contribution of the forest floor between Hinoki 156 (46%) and Hinoki 155 (69%) may relate to the presence of truck trail networks in the watershed. The truck trail network can play roles of sediment source and pathway for sediment from forest floor to stream channel due to the concentrated overland flow on the truck trail during heavy rainfall events. These results indicate that the forest floor should be recognized as a major source of suspended sediment in unmanaged Japanese cypress plantation watersheds. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
44.
For the Argo Project, monitoring the global upper ocean by a large number of profiling floats, maintaining the quality of
salinity data is critical; the goal for measurement accuracy is ±0.01. Experiments using the method of Wong et al. (2003), the standard delayed-mode quality control (dQC) for the Project, show that its performance depends critically on
the reference datasets used. This study concludes that the method is useful for Argo and has sufficient potential to achieve
the goal for salinity measurement in the North Pacific, when suitable reference datasets are prepared. Considering the Wong
et al. (2003) algorithms, we suggest that reference datasets with the following characteristics will be most suitable for Argo
dQC: They should be basically derived from the most extensive datasets, such as the latest World Ocean Database; in regions
with denser observations, datasets with carefully quality controls should be used; in the regions with subsurface temperature
inversions, such as the subarctic North Pacific, the profiles used for the reference must extend below the deepest temperature
maximum to prepare proper salinities for the deep layer reference. 相似文献
45.
Journal of Atmospheric Chemistry - Very short-lived substances (VSLs) are known to play an important role in ozone depletion in the troposphere and stratosphere. Environmental factors that... 相似文献
46.
Hakone caldera, now 8 by 12 km in diameter, was formed by collapse of a center of a volcano probably 2700 m high. The collapse took place at two separate periods each of which was followed by periods of deep denudation. The central part of the caldera has been covered by a thick pile of lavas of post-caldera cones and domes. For the purpose of finding thermal spring, drilling to depths of a few hundred to one thousand meters was carried out at various points within the caldera except for its central region. The study of the drill cores revealed that the average amount of subsidence at points 2 and 3 km away from the base of the present caldera wall is 600 m and 1200 m respectively, and probably more than 1800 m in the middle of the caldera. Within the caldera, the pre-caldera lavas and pyroclastic rocks are either lacking or much thinner than would be expected. It is concluded therefore that the present topographic depression of the caldera owed its origin to both subsidence and denudation. It is inferred that the subsidence took place along a complicated system of concentric faults combined with tilting of individual fault blocks toward the middle of the caldera. The magma reservoir into which the fault blocks sank probably had a shape of a cupola with a diameter comparable to or a little smaller than the diameter of the caldera. 相似文献
47.
Nagayoshi Katsuta Masao Takano Naomi Sano Yukinori Tani Shinya Ochiai Sayuri Naito Takuma Murakami Masakazu Niwa Shin‐ichi Kawakami 《Sedimentology》2019,66(6):2490-2510
Micro‐X‐ray fluorescence scanning spectroscopy of marine and lake sedimentary sequences can provide detailed palaeoenvironmental records through element intensity proxy data. However, problems with the effects of interstitial pore water on the micro‐X‐ray fluorescence intensities have been pointed out. This is because the X‐ray fluorescence intensities are measured directly at the surfaces of split wet sediment core samples. This study developed a new method for correcting X‐ray fluorescence data to compensate for the effects of pore water using a scanning X‐ray analytical microscope. This involved simultaneous use of micro‐X‐ray fluorescence scanning spectroscopy and an X‐ray transmission detector. To evaluate the interstitial pore water content from the X‐ray transmission intensities, a fine‐grained sediment core retrieved from Lake Baikal (VER99‐G12) was used to prepare resin‐embedded samples with smooth surfaces and uniform thickness. Simple linear regression between the linear absorption coefficients of the samples and their porosity, based on the Lambert–Beer law, enabled calculation of the interstitial pore spaces and their resin content with high reproducibility. The X‐ray fluorescence intensities of resin‐embedded samples were reduced compared with those of dry sediment samples because of: (i) the X‐ray fluorescence absorption of resin within sediment; and (ii) the sediment dilution effects by resin. An improved micro‐X‐ray fluorescence correction equation based on X‐ray fluorescence emission theory considers the instrument's sensitivity to each element, which provides a reasonable explanation of these two effects. The resin‐corrected X‐ray fluorescence intensity was then successfully converted to elemental concentrations using simple linear regression between the data from micro‐X‐ray fluorescence scanning spectroscopy and from the conventional analyzer. In particular, the calculated concentration of SiO2 over the depth of the core, reflecting diatom/biogenic silica concentration, was significantly changed by the calibrations, from a progressively decreasing trend to an increasing trend towards the top of the core. 相似文献
48.
The role of meso-scale eddies in mixed layer deepening and mode water formation in the western North Pacific 总被引:3,自引:1,他引:2
Shinya Kouketsu Hiroyuki Tomita Eitarou Oka Shigeki Hosoda Taiyo Kobayashi Kanako Sato 《Journal of Oceanography》2012,68(1):63-77
Distributions of mixed layer depths around the centers of anti-cyclonic and cyclonic eddies in the North Pacific Ocean were
composited by using satellite-derived sea surface height anomaly data and Argo profiling float data. The composite distributions
showed that in late winter, deeper mixed layers were more (less) frequently observed inside the cores of the anti-cyclonic
(cyclonic) eddies than outside. This relationship was the clearest in the region of 140°E–160°W and 35°N–40°N, where the temperature
and salinity of the deep mixed layers were similar to those of the lighter variety of central mode water (L-CMW). A simple
one-dimensional bulk mixed layer model showed that both strong sea-surface heat and momentum fluxes and weak preexisting stratification
contributed to formation of the deep mixed layer. These conditions were associated with the anti-cyclonic eddies, suggesting
that these eddies are important in the formation of mode waters, particularly L-CMW. 相似文献
49.
50.
A practical method is described of initiating a water mass curtain (a jet flow of water partitioning another body of water) to be used to control fish movements, along with its theoretical analysis. In this paper, equations to evaluate the change of density and upward flow rates in a water curtain due to entrainment are presented, and the accuracy of the equations is verified experimentally. The discontinuity of the density on the boundary between jet and ambient fluid was assumed in the analysis, since our experiments showed that the instantaneous density distribution was discontinuous. The equations are much simpler than the conventional formulae deduced by assuming a Gaussian curve, and are amenable to practical usage. The control efficiency of the water curtain is very good for young red sea bream. 相似文献