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301.
Shin’ichiro Kako Atsuhiko Isobe Satoquo Seino Azusa Kojima 《Journal of Oceanography》2010,66(2):291-297
The present study attempts to establish a scientifically reliable method capable of computing the drifting-object sources
and their outflows. First, the temporal variability of the drifting-object amount is investigated every two months on a beach
west of Japan, where various source regions are anticipated because of spatiotemporally variable northeastward ocean currents
over the East China Sea. Next, in order to specify drifting-object sources, two-way particle tracking model (PTM) experiments
are carried out using simulated ocean currents and leeway drift estimated from QuikSCAT/Seawinds wind data. Finally, an inverse
method with a Lagrange multiplier is applied to estimate drifting-object outflows at each source on the basis of the two-way
PTM results and beach surveys. Accuracy of object-source identification using the two-way PTM is validated by comparing disposable-lighter
sources suggested by phone numbers printed on the lighter surface with those computed by the model. In order to examine the
reliability of the inverse estimation, the number of plastic-bottle caps found in actual beach surveys is compared with that
computed using a forward in-time PTM during the same period of actual beach surveys, over which the outflows obtained using
the inverse method are given at each source in the model. 相似文献
302.
Shin Hyeon Ho Li Zhun Seo Min Ho Soh Ho Young Lim Weol Ae Park Jong Woo 《Ocean Science Journal》2019,54(4):685-691
Ocean Science Journal - There have been controversies regarding the taxonomy of Prorocentrum donghaiense, however Zhang et al. (2016) recently developed a probe with a quantitative real-time PCR... 相似文献
303.
Research and development of the New Generation Sea Surface Temperature for Open Ccean (NGSST-O) product and its demonstration operation 总被引:1,自引:0,他引:1
Futoki Sakaida Hiroshi Kawamura Shin Takahashi Teruhisa Shimada Yoshimi Kawai Kohtaro Hosoda Lei Guan 《Journal of Oceanography》2009,65(6):859-870
Real-time generation and distribution of the New Generation Sea Surface Temperature for Open Ocean (NGSST-O) product began
in September 2003 as a demonstration operation of the Global Ocean Data Assimilation Experiment (GODAE) High-Resolution Sea
Surface Temperature Pilot Project. Satellite sea surface temperature (SST) observations from infrared radiometers (AVHRR,
MODIS) and a microwave radiometer (AMSR-E) are objectively merged to generate the NGSST-O product, which is a quality-controlled,
cloud-free, high-spatial-resolution (0.05° gridded), wide-coverage (13–63° N, 116–166° E), daily SST digital map. The NGSST-O
demonstration operation system has been developed in cooperation with the Japanese Space Agency (JAXA) and has produced six
years of continuous data without gaps. Comparison to in situ SSTs measured by drifting buoys indicates that the root mean-square error of NGSST-O has been kept at approximately 0.9°C. 相似文献
304.
Shunsuke Tei Tomoki Morozumi Shin Nagai Shinya Takano Atsuko Sugimoto Ryo Shingubara Rong Fan Alexander Fedorov Tuyara Gavrilyeva Nikita Tananaev Trofim Maximov 《水文研究》2020,34(3):522-537
Flooding is one of the greatest disasters that produces strong effects on the ecosystem and livelihoods of the local population. Flood frequency is expected to increase globally making its risk assessment an urgent issue. In spring-summer 2017, an extreme flooding occurred in the Indigirka River lowland of Northeastern Siberia that inundated a large area. In this study, the extent and climatic drivers of the flooding were determined using the results of field observations, satellite images, and climate reanalysis dataset, and its possible effects on the ecosystem were discussed. In 2017, a significant lowland area of around 16,016 km2 was covered with water even in July, which was 5,217 km2 (around 4% of the total area) greater than the water-covered area in 2015 when usual hydrological condition in the area was observed. The hydrographic signature obtained for the Indigirka River water level in 2017 was unusual. Although the water level rose sharply at the end of May (which was typical for the Arctic region), it did not fall afterwards and even increased again to an annual daily maximum value in the middle of July. The climate reanalysis dataset obtained for the temporal–spatial variations of snow water equivalent, snowmelt, and runoff over the lowland revealed that a large amount of snowmelt runoff in June and July 2017 produced a large water-covered area and unusually high river water levels that lasted until summer. Snow depth from winter to spring was largest in 2017 over the period from 2009 to 2017, and the surface of the lower reach of the lowland was partially covered with snow even in the end of June due to the extreme snowfall that occurred in October 2016. Such unusual hydrological conditions waterlogged most trees over the lowland, which caused serious ecosystem devastation and changes in the material cycle. 相似文献
305.
This paper presents improvements to the global D8 (GD8) method for calculating single flow directions in a grid digital elevation model. Flow directions computed from grid digital elevation models serve as the foundation for much of the analysis and modeling of hydrological processes that are driven by topographic gradients. The literature includes both single flow direction methods, where flow goes to only one downslope cell, and multiple flow direction methods that apportion flow among multiple downslope cells. Among single flow direction methods, the standard D8 method, in which the flow direction is set based on the steepest local slope, results in bias on surfaces that do not align with the grid directions. Efforts to address this problem have led to the development of extended methods that account for elevation values further upslope in determining flow directions. We have identified discrepancies in one such method, GD8, and have examined ways to resolve these discrepancies. An improvement to GD8, named iGD8, is presented that allows replacing a reference cell from which path deviations are accumulated and that considers horizontal path deviation rather than global slope as a flow direction criterion. The improved method is found to be effective in resolving the problems encountered with GD8 and to be more efficient than a previously proposed alternative method (least transversal deviation (LTD) based D8, namely D8‐LTD) that uses recursive searching for the largest upstream area when multiple flow paths converge. The proposed improved GD8 method offers the opportunity for improved analysis and modeling of topographically driven hydrological processes by providing better foundational flow directions for these analyses. 相似文献
306.
We present a record of Holocene environmental change on the east coast of Korea, inferred using pollen, carbon-isotopic composition (??13C), total organic carbon, total sulfur, carbon/nitrogen ratios, particle size analysis and major element geochemistry in a sediment core from Soonpogae Lagoon. A multi-proxy paleoenvironmental approach had not previously been applied in Korea and allowed us to reconstruct climate and vegetation change, sea-level rise, lagoon development, and human impact on the east coast of Korea over the last 8,000?years. Evidence from Soonpogae Lagoon supports the following three conclusions: (1) As a drying trend prevailed on the east coast of Korea after ~5,900?cal?yr BP, chemical weathering weakened and herbaceous plants became more important than during the previous humid phase (Holocene Climate Optimum), (2) Sea-level rise on the east coast slowed dramatically about 6,800?cal?yr BP, resulting in low rates of sedimentation in Soonpogae Lagoon, and (3) Soonpogae Lagoon was almost completely isolated from the sea by sand barriers when human impact intensified ~2,100 BP. 相似文献
307.
Optical Characteristics of the Soft X-Ray Telescope Aboard <Emphasis Type="Italic">Yohkoh</Emphasis>
We have studied the point spread function (PSF) of the Yohkoh Soft X-ray Telescope (SXT) using the pre-launch calibration data. It is revealed from our study that both a careful consideration
on the undersampling effect and a proper choice of statistics are indispensable for determining the best fit analytical function
for the SXT PSF. We present the results of numerical simulations supporting our approach toward proper handling of the undersampled
PSF. Examples of the derived SXT PSF using a limited number of pre-launch calibration data are shown as a case study. 相似文献
308.
The structural, spectroscopic and phenanthrene binding characteristics were compared for humic acids (HA) extracted from two different sources: eight soils and six lake sediments. The elemental analysis revealed that HA from sediments had higher H/C, N/C, and (N + O)/C ratios compared to HA from soils, reflecting a lower degree of humification and more autochthonous organic input upon the formation of the HA for lake sediments versus soil environments. HA from soils exhibited a higher content of aromatic carbon structures than the sediment HA based on 13C NMR results. The source of HA was easily distinguished by comparing the synchronous fluorescence spectra of each HA group. The presence of a protein like fluorescence was prominent for the HA from sediment while it was minor for the HA from soil. Irrespective of the HA source, however, humification index (HIX) exhibited a common positive correlation with the aromatic content, and a negative correlation with O-alkyl carbon structures of the HA. The correlations were consistent with the general structural trends of humification processes, suggesting that HIX may serve as a source independent predictor to describe the structural information and humification degree of terrigenous HA. Aromatic carbon structures did contribute to enhancing the phenanthrene binding for both sources of HA. However, the primary structures associated with non-ideal phenanthrene binding (i.e., non-linear sorption isotherm) appear to differ by the HA source because the opposed correlations were obtained between aromaticity and the isotherm linearity for the two HA groups. Our results suggest that the HA structural function associated with specific non-linear sorption for hydrophobic organic contaminants (HOCs) may be more strongly governed by the HA source than by the apparent physico-chemical properties. 相似文献
309.
The study of the creation and evolution of the excavation disturbed zone (EDZ) in argillaceous rocks is a major issue for
the safety of nuclear wastes underground repositories. In this context, the argillaceous Tournemire site has provided a unique
opportunity to study the evolution of the EDZ with time thanks to the existence of three openings of different ages. A thorough
characterization of the EDZ has been conducted by different means such as visual observation, analysis of samples extracted
from drilled boreholes, EDZ permeability measurements, etc. On the basis of these measurements, a conceptual model of the
EDZ initiation and propagation at the Tournemire site has been proposed. In order to validate this model, numerical simulations
of increasing complexity have been carried out. In a first attempt, the response of the rock mass to the excavation phase,
followed by seasonal cyclic variations of temperature and relative humidity inside the opening, has been simulated by means
of a purely mechanical analysis, using a simple elastic material model. The EDZ has been estimated by post-processing the
calculated stress states, using a Mohr–Coulomb failure criterion. The results obtained show that no EDZ could be predicted
unless adopting a low cohesion value for the rock mass. Moreover, the deferred nature of the EDZ formation in Tournemire could
not be reproduced. These limitations have then been suppressed by using a coupled viscoplastic-damaging mechanical model,
the parameters of which have been identified from different laboratory experiments. With this model, a time evolution of the
EDZ could be predicted, but the EDZ pattern could not match the one observed in situ. Finally, in view of the importance of
the hydraulic couplings, unsaturated hydro-mechanical calculations have been carried out to investigate the effect of the
numerous seasonal variations cycles and the resulting shrinkage. 相似文献
310.
Young-Kwon Lim Steven Cocke D. W. Shin Justin T. Schoof Timothy E. LaRow James J. O’Brien 《Climate Dynamics》2010,35(2-3):449-471
Seasonally predicted precipitation at a resolution of 2.5° was statistically downscaled to a fine spatial scale of ~20 km over the southeastern United States. The downscaling was conducted for spring and summer, when the fine-scale prediction of precipitation is typically very challenging in this region. We obtained the global model precipitation for downscaling from the National Center for Environmental Prediction/Climate Forecast System (NCEP/CFS) retrospective forecasts. Ten member integration data with time-lagged initial conditions centered on mid- or late February each year were used for downscaling, covering the period from 1987 to 2005. The primary techniques involved in downscaling are Cyclostationary Empirical Orthogonal Function (CSEOF) analysis, multiple regression, and stochastic time series generation. Trained with observations and CFS data, CSEOF and multiple regression facilitated the identification of the statistical relationship between coarse-scale and fine-scale climate variability, leading to improved prediction of climate at a fine resolution. Downscaled precipitation produced seasonal and annual patterns that closely resemble the fine resolution observations. Prediction of long-term variation within two decades was improved by the downscaling in terms of variance, root mean square error, and correlation. Relative to the coarsely resolved unskillful CFS forecasts, the proposed downscaling drove a significant reduction in wet biases, and correlation increased by 0.1–0.5. Categorical predictability of seasonal precipitation and extremes (frequency of heavy rainfall days), measured with the Heidke skill score (HSS), was also improved by the downscaling. For instance, domain averaged HSS for two category predictability by the downscaling are at least 0.20, while the scores by the CFS are near zero and never exceed 0.1. On the other hand, prediction of the frequency of subseasonal dry spells showed limited improvement over half of the Georgia and Alabama region. 相似文献