Correction of the effect of relative wind direction on wind speed derived by advanced microwave scanning radiometer     

Masanori Konda  Akira Shibata  Naoto Ebuchi  Kohei Arai 《Journal of Oceanography》2006,62(3):395-404

The sea surface wind speed (SSWS) derived by a microwave radiometer can be contaminated by changes of the brightness temperature owing to the angle between the sensor azimuth and the wind direction (Relative Wind Direction effect: RWD effect). We attempt to apply the method proposed by Konda and Shibata (2004) to the SSWS derived by Advanced Microwave Scanning Radiometer (AMSR) on Advanced Earth Observing Satellite II (ADEOS-II), in order to correct for the RWD effect. The improvement of accuracy of the SSWS estimation amounts to roughly 60% of the error caused by the RWD effect. Comparison with in situ observation at the Tropical Atmosphere Ocean (TAO) array shows that the root mean square error of the corrected SSWS is 1.1 ms⁻¹. It is found that the impact of the RWD effect on the estimation of the latent heat flux can amount to about 30 Wm⁻² on average. We applied the method to the SSWS derived by AMSR for Earth Observing System (AMSR-E) and obtained a similar result.  相似文献   

Application of chemical tracers to an estimate of benthic denitrification in the Okhotsk Sea     

Masanori Ito  Yutaka W. Watanabe  Masahito Shigemitsu  Shinichi S. Tanaka  Jun Nishioka 《Journal of Oceanography》2014,70(5):415-424

To estimate benthic denitrification in a marginal sea, we assessed the usefulness of \({\text{N}}_{2}^{*}\) , a new tracer to measure the excess nitrogen gas (N₂) using dissolved N₂ and argon (Ar) with N* in the intermediate layer (26.6–27.4σ _θ ) of the Okhotsk Sea. The examined parameters capable of affecting \({\text{N}}_{2}^{*}\) are denitrification, air injection and rapid cooling. We investigated the relative proportions of these effects on \({\text{N}}_{2}^{*}\) using multiple linear regression analysis. The best model included two examined parameters of denitrification and air injection based on the Akaike information criterion as a measure of the model fit to data. More than 80 % of \({\text{N}}_{2}^{*}\) was derived from the denitrification, followed by air injection. Denitrification over the Okhotsk Sea shelf region was estimated to be 5.6 ± 2.4 μmol kg^?1. The distribution of \({\text{N}}_{2}^{*}\) was correlated with potential temperature (θ) between 26.6 and 27.4σ _θ (r = ?0.55). Therefore, we concluded that \({\text{N}}_{2}^{*}\) and N* can act complementarily as a quasi-conservative tracer of benthic denitrification in the Okhotsk Sea. Our findings suggest that \({\text{N}}_{2}^{*}\) in combination with N* is a useful chemical tracer to estimate benthic denitrification in a marginal sea.  相似文献   

Estimation of mean residence times of subsurface waters using seasonal variation in deuterium excess in a small headwater catchment in Japan     

Naoki Kabeya  Masanori Katsuyama  Masatoshi Kawasaki  Nobuhito Ohte  Atsuko Sugimoto 《水文研究》2007,21(3):308-322

We measured deuterium excess (d = δD ? 8δ¹⁸O) in throughfall, groundwater, soil water, spring water, and stream water for 3 years in a small headwater catchment (Matsuzawa, 0·68 ha) in the Kiryu Experimental Watershed in Japan. The d value represents a kinetic effect produced when water evaporates. The d value of the throughfall showed a sinusoidal change (amplitude: 6·9‰ relative to Vienna standard mean ocean water (V‐SMOW)) derived from seasonal changes in the source of water vapour. The amplitude of this sinusoidal change was attenuated to 1·3–6·9‰ V‐SMOW in soil water, groundwater, spring water, and stream water. It is thought that these attenuations derive from hydrodynamic transport processes in the subsurface and mixing processes at an outflow point (stream or spring) or a well. The mean residence time (MRT) of water was estimated from d value variations using an exponential‐piston flow model and a dispersion model. MRTs for soil water were 0–5 months and were not necessarily proportional to the depth. This may imply the existence of bypass flow in the soil. Groundwater in the hillslope zone had short residence times, similar to those of the soil water. For groundwater in the saturated zone near the spring outflow point, the MRTs differed between shallow and deeper groundwater; shallow groundwater had a shorter residence time (5–8 months) than deeper groundwater (more than 9 months). The MRT of stream water (8–9 months) was between that of shallow groundwater near the spring and deeper groundwater near the spring. The seasonal variation in the d value of precipitation arises from changes in isotopic water vapour composition associated with seasonal activity of the Asian monsoon mechanism. The d value is probably an effective tracer for estimating the MRT of subsurface water not only in Japan, but also in other East Asian countries influenced by the Asian monsoon. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Active optics experiments for thin meniscus mirror     

Masanori Iye 《Astrophysics and Space Science》1989,160(1-2):149-157

The concept of the active support system for JNLT is summarized. Performance of the force sensor, the optical wavefront analyzer, and the actuator under development for JNLT is reported. The results of a series of active optics experiments carried out by assembling these elements to support, measure, and actively correct a 62 cm thin mirror are described.Paper presented at the symposium on the JNLT and Related Engineering Development, Tokyo, November 29–December 2, 1988.  相似文献   

Current status and ecological roles of Zostera marina after recovery from large-scale reclamation in the Nakdong River estuary,Korea     

Sang Rul Park  Jong-Hyeob Kim  Chang-Keun Kang  Soonmo An  Ik Kyo Chung  Jeong Ha Kim  Kun-Seop Lee 《Estuarine, Coastal and Shelf Science》2009

Large Zostera marina meadows (covering 13.6 km²) existed in the Nakdong River estuary on the south coast of Korea until the mid-1980s, but these Z. marina beds nearly disappeared due to reclamation of adjacent mud flats for the construction of a port and industrial complex during the late 1980s. Partial recovery of Z. marina meadows occurred recently, and Z. marina coverage of about 0.3 km² was observed in this estuary. In this study, shoot morphology, density, biomass, productivity, and tissue nutrient content were measured to evaluate the current status of the Z. marina meadows by comparing these data to those for persistent seagrass meadows in similar geographical areas. Additionally, we examined the ecological roles of Z. marina in this estuary after recovery from the large-scale disturbance. Shoot density (151 shoots m⁻²) and total biomass (141 g DW m⁻²) in the estuary were similar to those reported from other Z. marina meadows in Korea. Annual leaf production (1726 g DW m⁻² y⁻¹) was higher than generally observed for Z. marina in other geographical areas. These results imply that the existing Z. marina meadows in this estuary have adjusted to local environmental conditions that changed after large-scale reclamation. Estimated annual whole plant carbon (C) and nitrogen (N) incorporations based on shoot production and tissue C and N content were 810.0 g C m⁻² y⁻¹ and 59.7 g N m⁻² y⁻¹, respectively. These values were equivalent to 2.4 × 10⁵ kg C y⁻¹ and 1.8 × 10⁴ kg N y⁻¹ for all Z. marina beds in the Nakdong River estuary. This high C and N incorporation into Z. marina tissues suggests that existing Z. marina meadows play important roles in C and N cycles in this estuary. Although the currently existing Z. marina beds in this estuary are persisting and play an important ecological role, anthropogenic factors that cause seagrass declines still affect the estuary. Thus, effective management and monitoring of Z. marina beds and environmental factors are critical to protecting and conserving this invaluable component of the Nakdong River estuary.  相似文献   

Genesis and Mixing/Mingling of Mafic and Felsic Magmas of Back-Arc Granite: Miocene Tsushima Pluton, Southwest Japan     

Ki-Cheol Shin    Masanori Kurosawa    Ryo Anma    Takanori Nakano 《Resource Geology》2009,59(1):25-50

The Middle Miocene Tsushima granite pluton is composed of leucocratic granites, gray granites and numerous mafic microgranular enclaves (MME). The granites have a metaluminous to slightly peraluminous composition and belong to the calc‐alkaline series, as do many other coeval granites of southwestern Japan, all of which formed in relation to the opening of the Sea of Japan. The Tsushima granites are unique in that they occur in the back‐arc area of the innermost Inner Zone of Southwest Japan, contain numerous miarolitic cavities, and show shallow crystallization (2–6 km deep), based on hornblende geobarometry. The leucocratic granite has higher initial ⁸⁷Sr/⁸⁶Sr ratios (0.7065–0.7085) and lower ε_Nd(t) (?7.70 to ?4.35) than the MME of basaltic–dacitic composition (0.7044–0.7061 and ?0.53 to ?5.24), whereas most gray granites have intermediate chemical and Sr–Nd isotopic compositions (0.7061–0.7072 and ?3.75 to ?6.17). Field, petrological, and geochemical data demonstrate that the Tsushima granites formed by the mingling and mixing of mafic and felsic magmas. The Sr–Nd–Pb isotope data strongly suggest that the mafic magma was derived from two mantle components with depleted mantle material and enriched mantle I (EMI) compositions, whereas the felsic magma formed by mixing of upper mantle magma of EMI composition with metabasic rocks in the overlying lower crust. Element data points deviating from the simple mixing line of the two magmas may indicate fractional crystallization of the felsic magma or chemical modification by hydrothermal fluid. The miarolitic cavities and enrichment of alkali elements in the MME suggest rapid cooling of the mingled magma accompanied by elemental transport by hydrothermal fluid. The inferred genesis of this magma–fluid system is as follows: (i) the mafic and felsic magmas were generated in the mantle and lower crust, respectively, by a large heat supply and pressure decrease under back‐arc conditions induced by mantle upwelling and crustal thinning; (ii) they mingled and crystallized rapidly at shallow depths in the upper crust without interaction during the ascent of the magmas from the middle to the upper crust, which (iii) led to fluid generation in the shallow crust. The upper mantle in southwest Japan thus has an EMI‐like composition, which plays an important role in the genesis of igneous rocks there.  相似文献   

The behaviour of dissolved silica during the mixing of river and sea waters in Tokyo Bay     

Akiyoshi Kamatani  Masanori Takano 《Estuarine, Coastal and Shelf Science》1984,19(5):505-512

The behaviour of dissolved silica was studied in Tokyo Bay during six surveys in 1979 and 1980. The data from late spring and mid-summer samples showed concave mixing curves of silica versus salinity, whereas for the winter samples a simple conservative dillution curve was obtained. Plots of particulate silicon to particulate aluminium showed that even for winter samples as well as summer ones there were some processes removing silica from solution. The processes could not be adequately explained by adsorption onto suspended solids. The data are indicative of uptake by diatoms as the principal removal mechanism. Most of the diatom skeletons settled to the bottom where dissolution was rapid. The silica-salinity curves in this study thus demonstrate an apparent removal process for dissolved silica. This is because during summer the displacement rate of biogenic silica from a unit water column to the bottom as fecal pellets or by sinking is greater than the supply rate of dissolved silica by the action of diffusion and mixing of bottom water enriched with dissolved silica whereas in winter these rates are reasonably balanced.  相似文献   

Partial derivative of love numbers     

Shuhei Okubo  Masanori Saito 《Journal of Geodesy》1983,57(1-4):167-179

We present a simple formula for the partial derivatives of Love numbers with respect to density, bulk modulus and rigidity without urging the Adams-Williamson condition in the liquid core. Partials of the second degree Love numbers are computed for model 1066 A. Love numbers prove to be either completely or virtually independent of the elastic profile within the whole core. Delta-function-like changes occur in Love numbers when we perturb the density of the top and bottom layers of the outer core.  相似文献   

Quantitative trace element analysis of single fluid inclusions by proton-induced X-ray emission (PIXE): application to fluid inclusions in hydrothermal quartz   总被引：1，自引：0，他引：1  

Masanori Kurosawa  Sadayoshi Shimano  Kunihiro Shima 《Geochimica et cosmochimica acta》2003,67(22):4337-4352

Single fluid inclusion analogues with known elemental composition and regular shape were analyzed for trace element contents by particle-induced X-ray emission (PIXE)—a nondestructive method for the analysis of single fluid inclusions—to evaluate the accuracy and detection limits of this type of analysis. Elements with concentrations of 10 to 1000 ppm were measured with average estimated relative error of ±7%. For natural fluid inclusions with 30 μm radius and 20 μm depth in quartz, the total analytical errors were estimated to be ±40% relative for Ca, ±16% for Fe, ±13% for Zn, ±12% for Sr, and ±11% for Br and Rb, by considering uncertainties in microscopic measurements of inclusion depths. Detection limits of 4 to 46 ppm for elements of mass numbers 25-50 were achieved for analyses of a spherical fluid inclusion with 30 μm radius and 20 μm depth in quartz, at an integrated charge of 1.0 μC. The trace element compositions of single fluid inclusions in a hydrothermal quartz crystal were also determined. The elemental concentrations in the inclusions varied widely: 0.2-9 wt.% for Ca and Fe, 300-8000 ppm for Mn and Zn, 40-3000 ppm for Cu, 100-4000 ppm for Br, Rb, Sr, and Pb, and less than 100 ppm for Ge. Elemental concentrations of secondary fluid inclusions on the same trail varied over an order of magnitude, even though all these inclusions were formed from the same fluid. Elemental concentrations in inclusions on the same trail are positively correlated with each other, except for Cu and Rb. Ratios of almost all elements in the inclusions on the trail were essentially unchanged; thus, the elemental ratios can provide original information on trace element compositions of a hydrothermal fluid.  相似文献   

III-3 A study on floating body of wave energy absorber     

Naomasa Iwasaki  Norimasa Takagi  Masanori Abe  Masaki Sakuta 《Ocean Engineering》1985,12(6):569

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