Observational Study on the Downward Solar Radiation at the Sea Surface in the Western Pacific     

Naoto Iwasaka  Yuichi Isozaki  Susumu Kuwashima  Hirotaka Otobe  Kimio Hanawa 《Journal of Oceanography》2000,56(6):717-726

In situ observation of downward solar radiation in the Western Pacific were carried out with voluntary merchant ships for five years from autumn 1990 through autumn 1995. Daily means of the short wave radiation were computed from the observed solar radiation. Then, the effects of shadows of the ship's superstructures on the observed radiation were corrected if needed. A 5-year average of short wave radiation along the main sea-lanes in the Western Pacific was calculated based on the observed daily mean solar radiation. Maximum values of 270–280 Wm^–2 are found around 15°–20°N in May and June, while those of 290 Wm^–2 are observed south of 18°S in November and December along the lanes. Small annual variations are found in the equatorial region. Annual mean values at the equator are about 230 Wm^–2 between New Guinea and Indonesia, and 200 Wm^–2 east of New Guinea. The 5-year average of short wave radiation was compared with the climatologies given in previous studies. We have concluded that some of results of previous studies are significantly underestimated.  相似文献   

地下RC结构物地震响应特征土工离心试验的模拟     

汪明武  Susumu Iai 《地震工程与工程振动》2007,27(3):150-155

地下结构物抗震稳定性的研究具有重要实际意义。基于动态土工离心试验,应用有效应力法分析了不同水平地震作用下土层和地下RC结构物的最大水平位移、不同埋深的土层加速度和超孔隙水压力变化规律,以及结构物的破坏发展特征,并进一步与试验结果进行了相互验证和对比,取得了较好效果,为重要地下结构物的抗震设计提供了依据和参考。  相似文献   

Electron beam emission from the EXOS-B (JIKIKEN) satellite as a powerful diagnostic tool in the magnetosphere     

Nobuki Kawashima  Kazunori Akai  Yukio Murasato  Susumu Sasaki 《Astrophysics and Space Science》1984,106(1):117-123

In an electron beam emission experiment on board the EXOS-B (JIKIKEN) satellite (200 V, 1 mA-maximum), several types of waves are strongly excited by the beam such as plasma frequency, upper hybrid frequency, electron cyclotron frequency, their harmonics and nonlinear coupling of these waves. Measurements of these waves give information on local plasma density and magnetic field strength and it is revealed that the electron beam emission from the spacecraft is a powerful diagnostic tool in the magnetosphere. A long term observation in this electron beam experiment has provided us with the average plasma density profile in the magnetosphere. It is also useful for the detection of the plasmapause. Plasma density measurements down to the order of 10 cm^–3 are possible. The instrument itself is very simple and compact, so that it will be a powerful plasma diagnostic tool in future magnetospheric and planetary explorations.  相似文献   

Ionospheric delay gradient model for GBAS in the Asia-Pacific region     

Saito  Susumu  Sunda  Surendra  Lee  Jiyun  Pullen  Sam  Supriadi  Slamet  Yoshihara  Takayuki  Terkildsen  Michael  Lecat  Frédéric 《GPS Solutions》2017,21(4):1937-1947

GPS Solutions - We investigated characteristics of anomalous spatial gradients in ionospheric delay on GNSS signals in the Asia-Pacific (APAC) low-magnetic latitude region in the context of the...  相似文献   

The Krakatau islands: The geotectonic setting     

Susumu Nishimura Dr.  H. Harjono Dr.  S. Suparka 《GeoJournal》1992,28(2):87-98

The Sunda Strait is located in a transitional zone between two different modes of subduction, the Java frontal and Sumatra oblique subductions. Western Java and Sumatra are, however, geologically continuous.The Krakatau complex lies at the intersection of two graben zones and a north-south active, shallow seismic belt, which coincides with a fracture zone along this seismic belt with fissure extrusion of alkali basaltic rocks commencing at Sukadana and continuing southward as far as the Panaitan island through Rajabasa, Sebuku and Krakatau.Paleomagnetic studies suggest that the island of Sumatra has been rotating clockwise relative to Java from at least 2.0 Ma to the present at a rate of 5–10h/Ma, and therefore the opening of the Sunda Strait might have started before 2 Ma (Nishimura et al. 1986).From geomorphological and seismological studies, it is estimated that the western part of Sumatra has been moving northward along the Semangko fault and the southern part of Sunda Strait has been pulled apart.Assuming that the perpendicular component (58 mm/yr; Fitch 1972) of the oblique subduction has not changed, we can estimate that the subduction started at 7–10 Ma. Huchon and LePichon (1984) also estimated that the subduction started at 13 Ma.Recent crustal earthquakes in the Sunda Strait area are clustered into three groups: (1) beneath the Krakatau complex where they are typically of tectonic origin, (2) inside a graben in the western part of the strait, and (3) in a more diffuse zone south of Sumatra. The individual and composite focal mechanisms of the events inside the strait show an extensional regime. A stress tensor, deduced from the individual focal mechanisms of the Krakatau group shows that the tensional axis has a N 130°E orientation (Harjono et al. 1988).These studies confirm that the Sunda Strait is under a tensional tectonic regime as a result of clockwise rotation along the continental margin and northward movement of the Sumatra sliver plate along the Semangko fault zone.  相似文献   

Seismic behaviour of pile groups by hybrid experiments     

Kenzo Toki  Tadanobu Sato  Junji Kiyono  Nozar Kishi Garmroudi  Susumu Emi  Masaaki Yoshikawa 《地震工程与结构动力学》1991,20(10):895-909

Non-linear seismic soil-pile interaction was studied with a hybrid procedure that used a pseudo-dynamic testing (PDT) method modified to account for frequency dependence and developed for foundation-soil systems. The numerical scheme used in the conventional PDT was improved by the introduction of a time-dependent pseudo-forcing function derived from the frequency-dependent dynamic characteristics of the system by Hilbert transformation in the frequency domain. Single, 2-, 3- and 9-pile group foundation models were used, their mechanical characteristics later being determined from static and forced vibration dynamic tests. Amplitude scaling was used for three recorded accelerograms. Data recorded during an earthquake at the site of the experiments revealed that the proposed methodology predicts well seismic nonlinear interaction and accounts for frequency dependence and non-linearity in the time domain.  相似文献   

Hybrid experiments on non-linear earthquake-induced soil-structure interaction     

Kenzo Toki  Tadanobu Sato  Junji Kiyono  Nozar Kishi Garmroudi  Susumu Emi  Masaaki Yoshikawa 《地震工程与结构动力学》1990,19(5):709-723

Non-linear seismic soil-structure interaction is studied through a hybrid procedure using the pseudo-dynamic testing (PDT) method which is modified to take into account frequency dependence and developed for foundation-soil systems. The numerical scheme used in conventional PDT is improved by introduction of a time-dependent pseudo-forcing function which is derived from frequency-dependent dynamic characteristics of the system by means of Hilbert transformation in the frequency domain. Surface, shallow and caisson foundation models that differed in size and depth of embedment were used. The mechanical characteristics of the systems were determined from static and forced vibration dynamic tests. An amplitude scaling technique was used for three recorded accelerograms.  相似文献   

Seasonal variability in carbon demand and flux by mesozooplankton communities at subarctic and subtropical sites in the western North Pacific Ocean     

T.?KobariEmail author  R.?Nakamura  K.?Unno  M.?Kitamura  K.?Tanabe  H.?Nagafuku  A.?Niibo  H.?Kawakami  K.?Matsumoto  M.?C.?Honda 《Journal of Oceanography》2016,72(3):403-418

We investigated seasonal changes in carbon demand and flux by mesozooplankton communities at subtropical (S1) and subarctic sites (K2) in the western North Pacific Ocean to compare the impact of mesozooplankton communities on the carbon budget in surface and mesopelagic layers. Fecal pellet fluxes were one order higher at K2 than at S1, and seemed to be enhanced by copepod and euphausiid egestion under high chlorophyll a concentrations. The decrease in pellet volume and the lack of any substantial change in shape composition during sink suggest a decline in fecal pellet flux due to coprorhexy and coprophagy. While respiratory and excretory carbon by diel migrants at depth (i.e., active carbon flux) was similar between the two sites, the actively transported carbon exceeded sinking fecal pellets at S1. Mesozooplankton carbon demand in surface and mesopelagic layers was higher at K2 than S1, and an excess of demand to primary production and sinking POC flux was found during some seasons at K2. We propose that this demand was met by supplementary carbon sources such as feeding on protozoans and fecal pellets at the surface and carnivory of migrants at mesopelagic depths.  相似文献   

Seasonal changes in the mesozooplankton biomass and community structure in subarctic and subtropical time-series stations in the western North Pacific     

Minoru Kitamura  Toru Kobari  Makio C. Honda  Kazuhiko Matsumoto  Kosei Sasaoka  Rie Nakamura  Kazuyuki Tanabe 《Journal of Oceanography》2016,72(3):387-402

Seasonal changes in mesozooplankton biomass and their community structures were observed at time-series stations K2 (subarctic) and S1 (subtropical) in the western North Pacific Ocean. At K2, the maximum biomass was observed during the spring when primary productivity was still low. The annual mean biomasses in the euphotic and 200- to 1000-m layers were 1.39 (day) and 2.49 (night) g C m^?2 and 4.00 (day) and 3.63 (night) g C m^?2, respectively. Mesozooplankton vertical distribution was bimodal and mesopelagic peak was observed in a 200- to 300-m layer; it mainly comprised dormant copepods. Copepods predominated in most sampling layers, but euphausiids were dominant at the surface during the night. At S1, the maximum biomass was observed during the spring and the peak timing of biomass followed those of chlorophyll a and primary productivity. The annual mean biomasses in the euphotic and 200- to 1000-m layers were 0.10 (day) and 0.21 (night) g C m^?2 and 0.47 (day) and 0.26 (night) g C m^?2, respectively. Copepods were dominant in most sampling layers, but their mean proportion was lower than that in K2. Mesozooplankton community characteristics at both sites were compared with those at other time-series stations in the North Pacific and with each other. The annual mean primary productivities and sinking POC fluxes were equivalent at both sites; however, mesozooplankton biomasses were higher at K2 than at S1. The difference of biomasses was probably caused by differences of individual carbon losses, population turnover rates, and trophic structures of communities between the two sites.  相似文献   

Identification of aryl hydrocarbon receptor 2 in aquatic birds; cDNA cloning of AHR1 and AHR2 and characteristics of their amino acid sequences     

Yasui T  Kim EY  Iwata H  Tanabe S 《Marine environmental research》2004,58(2-5):113-118

The toxic effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and its related planar halogenated aromatic hydrocarbons (PHAHs) are mediated by the aryl hydrocarbon receptor (AHR). To investigate the potential sensitivity to PHAHs and the evolutional diversity of AHR in aquatic birds, AHR cDNAs were initially cloned and sequenced from the livers of a black-footed albatross (Diomedea nigripes) and a common cormorant (Phalacrocorax carbo). In this study, we report the identification of two distinct AHR paralog genes in these species. The two full-length AHR cDNAs from albatross were highly divergent (33% overall amino acid identity, and 60% identity in the N-terminal half). Phylogenetic analysis showed that one of them belongs to the AHR1 clade and the other one to the AHR2 clade, which has been identified only from fishes, but not yet from mammals and birds. Albatross AHR1 encoded a 861-residue protein with a predicted molecular mass of 96.7 kDa, and in the case of albatross AHR2, 925 amino acids and 100.7 kDa. From cormorant liver, the full-length AHR1 cDNA and the partial AHR2 cDNA were cloned. This result strongly suggests that bird species also possess two distinct AHR genes (AHR1 and AHR2). To our knowledge, this is the first report on the presence of an AHR2-like isoform in bird species as well as in fish.  相似文献