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151.
Blanco AC Watanabe A Nadaoka K Motooka S Herrera EC Yamamoto T 《Marine pollution bulletin》2011,62(4):770-785
Radon (222Rn) measurements were conducted in Shiraho Reef (Okinawa, Japan) to investigate nearshore submarine groundwater discharge (SGDnearshore) dynamics. Estimated average groundwater flux was 2-3 cm/h (maximum 7-8 cm/h). End-member radon concentration and gas transfer coefficient were identified as major factors influencing flux estimation accuracy. For the 7-km long reef, SGDnearshore was 0.39-0.58 m3/s, less than 30% of Todoroki River’s baseflow discharge. SGDnearshore was spatially and temporally variable, reflecting the strong influence of subsurface geology, tidal pumping, groundwater recharge, and hydraulic gradient. SGDnearshore elevated nearshore nitrate concentrations (0.8-2.2 mg/l) to half of Todoroki River’s baseflow -N (2-4 mg/L). This increased nearshore Chl-a from 0.5-2 μg/l compared to the typically low Chl-a (<0.1-0.4 μg/l) in the moat. Diatoms and cyanobacteria concentrations exhibited an increasing trend. However, the percentage contributions of diatoms and cyanobacteria significantly decreased and increased, respectively. SGD may significantly induce the proliferation of cyanobacteria in nearshore reef areas. 相似文献
152.
153.
Sachiko Oguma Tsuneo Ono Yutaka W. Watanabe Hiromi Kasai Shuichi Watanabe Daiki Nomura Humio Mitsudera 《Estuarine, Coastal and Shelf Science》2011
In this study, we examined the relationship between the low salinity water in the shelf region of the southern Okhotsk Sea which was seasonally sampled (0–200 m), and fluxes of low salinity water from Aniva Bay. To express the source of freshwater mixing in the surface layer, we applied normalized total alkalinity (NTA) and stable isotopes of seawater as chemical tracers. NTA-S diagrams indicate that NTA of low salinity water in the upper 30 m layer just off the Soya Warm Current is clearly higher than in the far offshore region in summer and autumn. Using NTA-S regression lines, we could deduce that the low salinity and high NTA water in the upper layer originates from Aniva Bay. For convenience, we defined this water as the Aniva Surface Water (ASW) with values S < 32, NTA > 2450 μmol kg−1. Formation and transport processes of ASW are discussed using historical data. The interaction between the maximum core of high NTA water on the bottom slope of eastern Aniva Bay and an anticyclonic eddy at the mouth of Aniva Bay are concluded to control ASW formation. Upwelling of the Cold Water Belt water at the tip of Cape Krillion is considered to cause ASW outflow from Aniva Bay. 相似文献
154.
Yasuhiro Oba Takeshi Chigai Yoshihiro Osamura Naoki Watanabe Akira Kouchi 《Meteoritics & planetary science》2014,49(1):117-132
We experimentally studied hydrogen (H)–deuterium (D) substitution reactions of solid methylamine (CH3NH2) under astrophysically relevant conditions. We also calculated the potential energy surface for the H–D substitution reactions of methylamine isotopologues using quantum chemical methods. Despite the relatively large energy barrier of more than 18 kJ mol?1, CH3NH2 reacted with D atoms to yield deuterated methylamines at 10 K, suggesting that the H–D substitution reaction proceeds through quantum tunneling. Deuterated methylamines reacted with H atoms as well. On the basis of present results, we propose that methylamine has potential for D enrichment through atomic surface reactions on interstellar grains at very low temperatures in molecular clouds. D enrichment would occur in particular in the methyl group of methylamine. 相似文献
155.
Boehnhardt Hermann Barucci Antonella Delsanti Audrey De Bergh Catherine Doressoundiram Alain Romon Jennifer Dotto Elisabetta Tozzi Gianpaolo Lazzarin Monica Fornasier Sonia Peixinho Nuno Hainaut Olivier Davies John Rousselot Philippe Barrera Luis Birkle Kurt Meech Karen Ortiz JoseLuis Sekiguchi Tomohiko Watanabe Jun-ichi Thomas Nick West Richard 《Earth, Moon, and Planets》2003,92(1-4):145-156
BVRI photometry of 107 TNOs and Centaurs establishes the range of spectral gradients to be between –5 to 55%/100 nm (with one exception). A cluster of very red Cubewanos is firmly identified in orbits of low inclination and eccentricity beyond 40 AU from the Sun. Further correlations between surface colours and dynamical parameters (inclination and perihelion distance) are suggested for Cubewanos and scattered disk objects, but lack complete confidence for their reality. Plutinos and Centaurs do not show any clear correlation between surface colours and orbital parameters. We present in this paper 12 spectra obtained in the visible region and nine of them for which we obtained also near infrared spectra up to 2.4 microns. A few other objects have been observed, but the data are still under reduction and analysis. The principal reported results obtained are: (i) a wide range of visible slopes; (ii) evidence for surface variations on 2001 PT13; and (iii) possible detection of few percent of water ice (1999 TC36}, 2000 EB173, 1999 DE9, 2001 PT13, 2000 QC243, 1998 SG35). 相似文献
156.
The measurement of river discharge is necessary for understanding many water‐related issues. Traditionally, river discharge is estimated by measuring water stage and converting the measurement to discharge by using a stage–discharge rating curve. Our proposed method for the first time couples the measurement of water‐surface width with river width–stage and stage–discharge rating curves by using very high‐resolution satellite data. We used it to estimate the discharge in the Yangtze (Changjiang) River as a case study. The discharges estimated at four stations from five QuickBird‐2 images matched the ground observation data very well, demonstrating that the proposed approach can be regarded as ancillary to traditional field measurement methods or other remote methods to estimate river discharge. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
157.
The evolution of hot thermal plasma in solar flares is analyzed by a single-temperature model applied to continuum emission in the 5 keV < E ? 13 keV spectral range. The general trend that the thermal plasma observed in soft X-rays is heated by the non-thermal electrons that emit as the hard X-ray bursts is confirmed by the observation of an electron temperature increase at the time interval of hard X-ray spikes and a quantitative comparison between thermal energy content and hard X-ray energy input. Non-thermal electrons of 10 keV < E < 30 keV energy may play an important role in pre- and post-burst phases. 相似文献
158.
Jun-ichi Watanabe 《Earth, Moon, and Planets》2004,95(1-4):49-61
Recent progress on the interrelation between meteor streams and comets is reviewed both on dynamical and physical aspects.
The topics include the recent concept of the structure of meteor streams, resulted success of the prediction of the meteor
storms, and the recent observational situation on the cometary dust grains and meteoroids. Two possible explanations for the
origin of the meteoroids together with the implication for the relation between the birthplace of the parent comets and the
meteoroids are discussed. 相似文献
159.
Ken T. Murata Praphan Pavarangkoon Atsushi Higuchi Koichi Toyoshima Kazunori Yamamoto Kazuya Muranaga Yoshiaki Nagaya Yasushi Izumikawa Eizen Kimura Takamichi Mizuhara 《Earth Science Informatics》2018,11(2):217-237
It has been almost four decades since the first launch of geostationary meteorological satellite by Japan Meteorological Agency (JMA). The specifications of the geostationary meteorological satellites have shown tremendous progresses along with the generations, which are now entering their third generation. The third-generation geostationary meteorological satellites not only yield basic data for weather monitoring, but also globally observe the Earth’s environment. The development of multi-band imagers with improved spatial resolution onboard the third-generation geostationary meteorological satellites brings us meteorological data in larger size than those of the second-generation ones. Thus, new techniques for domestic and world-wide dissemination of the observational big data are needed. In this paper, we develop a web-based data visualization for Himawari-8 satellite sensed images in real time and with full resolution. This data visualization is supported by the ecosystems, which uses a tiled pyramid representation and parallel processing technique for terrain on an academic cloud system. We evaluate the performance of our techniques for domestic and international users on laboratory experiments. The results show that our data visualization is suitable for practical use on a temporal preview of observation image data for the domestic users. 相似文献
160.