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101.
Hiroshi Murakami Kosei Sasaoka Kohtaro Hosoda Hajime Fukushima Mitsuhiro Toratani Robert Frouin B. Greg Mitchell Mati Kahru Pierre-Yves Deschamps Dennis Clark Stephanie Flora Motoaki Kishino Sei-Ichi Saitoh Ichio Asanuma Akihiko Tanaka Hiroaki Sasaki Katsumi Yokouchi Yoko Kiyomoto Hiroaki Saito Cécile Dupouy Absornsuda Siripong Satsuki Matsumura Joji Ishizaka 《Journal of Oceanography》2006,62(3):373-393
The Global Imager (GLI) aboard the Advanced Earth Observing Satellite-II (ADEOS-II) made global observations from 2 April
2003 to 24 October 2003. In cooperation with several institutes and scientists, we obtained quality controlled match-ups between
GLI products and in-situ data, 116 for chlorophyll-a concentration (CHLA), 249 for normalized water-leaving radiance (nLw) at 443 nm, and 201 for
aerosol optical thickness at 865 nm (Tau_865) and Angstrom exponent between 520 and 865 nm (Angstrom). We evaluated the GLI
ocean color products and investigated the causes of errors using the match-ups. The median absolute percentage differences
(MedPD) between GLI and in-situ data were 14.1–35.7% for nLws at 380–565 nm, 52.5–74.8% nLws at 625–680 nm, 47.6% for Tau_865, 46.2% for Angstrom, and 46.6%
for CHLA, values that are comparable to the ocean-color products of other sensors. We found that some errors in GLI products
are correlated with observational conditions; nLw values were underestimated when nLw at 680 nm was high, CHLA was underestimated
in absorptive aerosol conditions, and Tau_865 was overestimated in sunglint regions. The error correlations indicate that
we need to improve the retrievals of the optical properties of absorptive aerosols and seawater and sea surface reflection
for further applications, including coastal monitoring and the combined use of products from multiple sensors. 相似文献
102.
Observations of sediment contamination along the coast of Japan were analyzed. When the pollutant concentration is divided by the fine particle fraction in the sediment, a regular pattern is observed in the quantitative relationship among the degree and the area of contamination and the discharge rate of pollutant released continuously into the water along the coast. This regularity was observed with respect to COD,n-hexane soluble substances and heavy metals, and could be expressed by a formula.Polluted particles were supposed to disperse through suspension in the bottom water layer, and thus their distribution in the surface sediment is expected to become similar to effluent dispersion in the surface water. 相似文献
103.
Nobuki Kawashema
Naoshi Fukushima
《Planetary and Space Science》1964,12(12):1187-1190A laboratory experiment is designed to study the interaction of the solar wind with the geomagnetic field. Time-exposure and time-resolved photographs are taken when plasma hits a model Earth, and direct measurements are made of the magnetic field change, plasma density and electric current distribution. The shape of the magnetic cavity formed on the upstream side of the model Earth is almost the same as that calculated for the geomagnetic cavity. The charged particles, which penetrate the magnetic cavity formed on the upstream side of the model Earth with east-west asymmetry from the neutral points on the cavity surface, appear to concentrate towards the equator on the rear side of the model, forming a westward electric current belt within the magnetosphere. When the dipole axis is not perpendicular to the plasma gun—magnetic dipole line, the invasion of plasma is more pronounced at the cusp of the cavity nearer to the gun. Charged particles appear to penetrate to a greater extent if a uniform external magnetic field is applied parallel to the magnetic dipole than if one is applied antiparallel. 相似文献
104.
Masahiro Takenobu Masafumi Miyata Yu Otake Takehiko Sato 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2019,13(3):195-204
ABSTRACTThe Partial Factor Method (PFM) based on the Level 1 reliability design method was introduced in 2007 to the Technical Standards for Port and Harbour Facilities (TSPHF-2007) in Japan. After nearly 10 years of practical use of TSPHF-2007, the design standard has been revised based on requests from the practitioners who recommend the transition from the PFM to the Load Resistance Factor Design (LRFD). In this paper, we discuss the setting method of the target failure probability to determine the partial factors based on code calibration. Furthermore, we examine the impacts of implementing the LRFD concept to the TSPHF by taking the sliding and overturning of a gravity type quay wall as an example to represent port and harbour facilities. We found no practical difference in caisson width derived using the LRFD and the PFM, whereas the degree of matching of the target failure probability was somewhat more precise for the PFM. This finding indicates that the LRFD is a more reasonable design method than the PFM in terms of the simplicity of the performance function itself and the ease of engineering interpretation during the design procedure. 相似文献
105.
Takehiko Hiwatari Kunio Shirasawa Yasushi Fukamachi Ryuichi Nagata Tomoyoshi Koizumi Hiroshi Koshikawa Kunio Kohata 《Polar Science》2008,2(1):41-54
Downward material fluxes under seasonal sea ice were measured using a time-series sediment trap installed at an offshore site in the Okhotsk Sea north of Hokkaido, Japan, from 13 January to 23 March 2005. The maximum fluxes of lithogenic material (753 mg m−2 day−1) and organic matter (mainly detritus; 333 mg m−2 day−1) were recorded during the period in which sea ice drifted ashore and increased in extent, from 13 January to 9 February. Organic matter as fecal pellets (81–93 mg m−2 day−1) and opal as biosilica (51–67 mg m−2 day−1), representing diatom fluxes, were abundant in sediment trap samples obtained during the period of full sea ice coverage from 10 February to 9 March. Microscopic observations revealed that fecal pellets were largely diatom frustules, suggesting that zooplankton actively grazed on ice algae during the period of full sea ice coverage. During the period of retreating sea ice, from 10 to 23 March, the phytoplankton flux showed a rapid increase (from 9.5 to 22.5 × 106 cells m−2 day−1), reflecting their release into the water column as the sea ice melted. Our results demonstrate that the quantity and quality of sinking biogenic and lithogenic materials vary with the seasonal extent of sea ice in mid-winter. 相似文献
106.
Toshio Fukushima 《Celestial Mechanics and Dynamical Astronomy》1999,73(1-4):231-241
This paper reviews three recent works on the numerical methods to integrate ordinary differential equations (ODE), which are
specially designed for parallel, vector, and/or multi-processor-unit(PU) computers. The first is the Picard-Chebyshev method
(Fukushima, 1997a). It obtains a global solution of ODE in the form of Chebyshev polynomial of large (> 1000) degree by applying
the Picard iteration repeatedly. The iteration converges for smooth problems and/or perturbed dynamics. The method runs around
100-1000 times faster in the vector mode than in the scalar mode of a certain computer with vector processors (Fukushima,
1997b). The second is a parallelization of a symplectic integrator (Saha et al., 1997). It regards the implicit midpoint rules
covering thousands of timesteps as large-scale nonlinear equations and solves them by the fixed-point iteration. The method
is applicable to Hamiltonian systems and is expected to lead an acceleration factor of around 50 in parallel computers with
more than 1000 PUs. The last is a parallelization of the extrapolation method (Ito and Fukushima, 1997). It performs trial
integrations in parallel. Also the trial integrations are further accelerated by balancing computational load among PUs by
the technique of folding. The method is all-purpose and achieves an acceleration factor of around 3.5 by using several PUs.
Finally, we give a perspective on the parallelization of some implicit integrators which require multiple corrections in solving
implicit formulas like the implicit Hermitian integrators (Makino and Aarseth, 1992), (Hut et al., 1995) or the implicit symmetric
multistep methods (Fukushima, 1998), (Fukushima, 1999).
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
107.
Hsu YY Hsiung TL Paul Wang H Fukushima Y Wei YL Chang JE 《Marine pollution bulletin》2008,57(6-12):873-876
The nitrogen-doped TiO(2) nanotube (N-TNT) thin films were synthesized using ZnO nanorods as the template and doped with urea at 623K. Under ultraviolet (UV) and visible light irradiation, the efficiencies for photocatalytic degradation of methylene blue is as high as 30%. About 10% of toluene (representing aromatics in the spill oils) in sea water can be photocatalytically degraded under visible light radiation for 120 min. The aliphatic model compound (1-hexadecene) has, on the contrary, a less efficiency (8%) on the N-TNT photocatalyst. On the average, under visible light radiation, the effectnesses of the N-TNT for photocatalytic degradation of model compounds in the spill oils in sea water are 0.38 mg toluene/gN-TNTh and 0.25 mg 1-hexadecene/gN-TNTh. It is expected that spill oils in the harbors or seashores can be adsorbed and photocatalytically degraded on the N-TNT thin films that are coated onto levee at the sea water surface level. 相似文献
108.
Takehiko Nose Adrean Webb Takuji Waseda Jun Inoue Kazutoshi Sato 《Ocean Dynamics》2018,68(10):1383-1402
A predictability study on wave forecast of the Arctic Ocean is necessary to help identify hazardous areas and ensure sustainable shipping along the trans-Arctic routes. To assist with validation of the Arctic Ocean wave model, two drifting wave buoys were deployed off Point Barrow, Alaska for two months in September 2016. Both buoys measured significant wave heights exceeding 4 m during two different storm events on 19 September and 22 October. The NOAA-WAVEWATCH III? model with 16-km resolution was forced using wind and sea ice reanalysis data and obtained general agreement with the observation. The September storm was reproduced well; however, model accuracy deteriorated in October with a negative wave height bias of around 1 m during the October storm. Utilising reanalysis data, including the most up-to-date ERA5, this study investigated the cause: grid resolution, wind and ice forcing, and in situ sea level pressure observations assimilated for reanalysis. The analysis has found that there is a 20% reduction of in situ SLP observations in the area of interest, presumably due to fewer ships and deployment options during the sea ice advance period. The 63-member atmospheric ensemble reanalysis, ALERA2, has shown that this led to a larger ensemble spread in the October monthly mean wind field compared to September. Since atmospheric physics is complex during sea ice advance, it is speculated that the elevated uncertainty of synoptic-scale wind caused the negative wave model bias. This has implications for wave hindcasts and forecasts in the Arctic Ocean. 相似文献
109.
110.
Toshio Fukushima 《Journal of Geodesy》2012,86(9):745-754
The existing methods to compute the definite integral of associated Legendre function (ALF) with respect to the argument suffer from a loss of significant figures independently of the latitude. This is caused by the subtraction of similar quantities in the additional term of their recurrence formulas, especially the finite difference of their values between two endpoints of the integration interval. In order to resolve the problem, we develop a recursive algorithm to compute their finite difference. Also, we modify the algorithm to evaluate their definite integrals assuming that their values at one endpoint are known. We numerically confirm a significant increase in computing precision of the integral by the new method. When the interval is one arc minute, for example, the gain amounts to 2–4 digits for the degree of harmonics in the range 2 ≤ n ≤ 2,048. This improvement in precision is achieved at a negligible increase in CPU time, say less than 5%. 相似文献