Variable stars in the Magellanic Clouds – II. The data and infrared properties     

Yoshifusa Ita †  Toshihiko Tanabé  Noriyuki Matsunaga  Yasushi Nakajima  Chie Nagashima  Takahiro Nagayama  Daisuke Kato  Mikio Kurita  Tetsuya Nagata  Shuji Sato  Motohide Tamura  Hidehiko Nakaya  Yoshikazu Nakada 《Monthly notices of the Royal Astronomical Society》2004,353(3):705-712

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Assessing decarbonization pathways and their implications for energy security policies in Japan     

Ken Oshiro  Mikiko Kainuma  Toshihiko Masui 《Climate Policy》2016,16(4):S63-S77

For countries without sufficient fossil fuel resources such as Japan, climate policies in the mid- to long term need to satisfy requirements not only for decarbonisation but also for energy security in the context of limitations on renewable energies and nuclear power. This study assesses the feasibility of decarbonization pathways to 2050 and their effects on energy security, considering the latest energy and climate policies in Japan using the AIM/Enduse model. The analysis illustrates that deep decarbonization by 2050 is technically feasible even without nuclear power based on three elements: energy efficiency improvements, low-carbon electricity and electrification in end-use sectors. These decarbonization pathways, in the long term, could also contribute to enhanced energy security, reducing import dependency to less than a half of the total primary energy and reducing import bills for fossil fuels by around 70% compared with the current level. Notably, renewable energies could play a strategically significant role in satisfying both climate and energy security requirements. In the mid-term (to 2030), however, although GHG emissions are reduced by 14–20% from 1990 levels, import dependency is relatively stable at today's levels, particularly without the restart of nuclear power. Given the limited potential for renewable energies in the mid-term, it is suggested that the availability of nuclear power will have negative impacts on carbon intensity and energy security, and policies to enhance the security of fossil fuels, including diversification of fuel sources and supply routes, will be required for the foreseeable future.

Policy relevance

Considering the scarcity of indigenous fossil fuel resources and the uncertain availability of nuclear power in Japan, renewable energy could play a strategically significant role in replacing unabated fossil fuels, which would contribute to satisfying both climate and energy security requirements in the long term. However, the renewable energy potential is insufficient to eliminate the requirement for fossil fuels by 2030; therefore the unavailability of nuclear power would affect energy security considerably. Thus, policies in the mid-term would still require enhancement of the energy security of fossil fuels, including the diversification of fuel sources and supply routes, as well as alleviation of the impacts of price volatility.  相似文献   

Evidence of thermal pressurization in high‐velocity friction experiments on smectite‐rich gouges     

Fabio Ferri  Giulio Di Toro  Takehiro Hirose  Toshihiko Shimamoto 《地学学报》2010,22(5):347-353

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Impact-induced N₂ production from ammonium sulfate: Implications for the origin and evolution of N₂ in Titan’s atmosphere     

Sho Fukuzaki  Hidenori Genda  Toshihiko Kadono 《Icarus》2010,209(2):715-722

Chemical reactions and volatile supply through hypervelocity impacts may have played a key role for the origin and evolution of both planetary and satellite atmospheres. In this study, we evaluate the role of impact-induced N₂ production from reduced nitrogen-bearing solids proposed to be contained in Titan’s crust, ammonium sulfate ((NH₄)₂SO₄), for the replenishment of N₂ to the atmosphere in Titan’s history. To investigate the conversion of (NH₄)₂SO₄ into N₂ by hypervelocity impacts, we measured gases released from (NH₄)₂SO₄ that was exposed to hypervelocity impacts created by a laser gun. The sensitivity and accuracy of the measurements were enhanced by using an isotope labeling technique for the target. We obtained the efficiency of N₂ production from (NH₄)₂SO₄ as a function of peak shock pressure ranging from ∼8 to ∼45 GPa. Our results indicate that the initial and complete shock pressures for N₂ degassing from (NH₄)₂SO₄ are ∼10 and ∼25 GPa, respectively. These results suggest that cometary impacts on Titan (i.e., impact velocity v_i > ∼8 km/s) produce N₂ efficiently; whereas satellitesimal impacts during the accretion (i.e., v_i < 4 km/s) produce N₂ only inefficiently. Even when using the proposed small amount of (NH₄)₂SO₄ content in the crust (∼4 wt.%) (Fortes, A.D. et al., 2007. Icarus 188, 139-153), the total amount of N₂ provided through cometary impacts over 4.5 Ga reaches ∼2-6 times the present atmospheric N₂ (i.e., ∼7 × 10²⁰-2 × 10²¹ [mol]) based on the measured production efficiency and results of a hydrodynamic simulation of cometary impacts onto Titan. This implies that cometary impacts onto Titan’s crust have the potential to account for a large part of the present N₂ through the atmospheric replenishment after the accretion.  相似文献   

A ground-based observation of the LCROSS impact events using the Subaru Telescope     

Peng K. Hong  Seiji Sugita  Yasuhito Sekine  Naruhisa Takatoh  Tetsuharu Fuse  Hideyo Kawakita  Eliot F. Young  Kosuke Kurosawa  Junichi Haruyama  Toshihiko Kadono  Shunichi Kamata  Tomohiko Sekiguchi  Hirotomo Noda 《Icarus》2011,214(1):21-29

The Lunar Crater Observation and Sensing Satellite (LCROSS) mission was an impact exploration searching for a volatile deposit in a permanently shadowed region (PSR) by excavating near-surface material. We conducted infrared spectral and imaging observations of the LCROSS impacts from 15 min before the first collision through 2 min after the second collision using the Subaru Telescope in order to measure ejecta dust and water. Such a ground-based observation is important because the viewing geometry and wavelength coverage are very different from the LCROSS spacecraft. We used the Echelle spectrograph with spectral resolution λ/Δλ ∼ 10,000 to observe the non-resonant H₂O rotational emission lines near 2.9 μm and the slit viewer with a K′ filter for imaging observation of ejecta plumes. Pre-impact calculations using a homogeneous projectile predicted that 2000 kg of ejecta and 10 kg of H₂O were excavated and thrown into the analyzed area immediately above the slit within the field of view (FOV) of the K′ imager and the FOV of spectrometer slit, respectively. However, no unambiguous emission line of H₂O or dust was detected. The estimated upper limits of the amount of dust and H₂O from the main Centaur impact were 800 kg and 40 kg for the 3σ of noise in the analyzed area within the imager FOV and in the slit FOV, respectively. If we take 1σ as detection limit, the upper limits are 300 kg and 14 kg, respectively. Although the upper limit for water mass is comparable to a prediction by a standard theoretical prediction, that for dust mass is significantly smaller than that predicted by a standard impact theory. This discrepancy in ejecta dust mass between a theoretical prediction and our observation result suggests that the cratering process induced by the LCROSS impacts may have been substantially different from the standard cratering theory, possibly because of its hollow projectile structure.  相似文献   

Emission scenario dependencies in climate change assessments of the hydrological cycle   总被引：1，自引：1，他引：0  

Hideo Shiogama  Naota Hanasaki  Yuji Masutomi  Tatsuya Nagashima  Tomoo Ogura  Kiyoshi Takahashi  Yasuaki Hijioka  Toshihiko Takemura  Toru Nozawa  Seita Emori 《Climatic change》2010,99(1-2):321-329

Anthropogenic global warming will lead to changes in the global hydrological cycle. The uncertainty in precipitation sensitivity per 1 K of global warming across coupled atmosphere-ocean general circulation models (AOGCMs) has been actively examined. On the other hand, the uncertainty in precipitation sensitivity in different emission scenarios of greenhouse gases (GHGs) and aerosols has received little attention. Here we show a robust emission-scenario dependency (ESD); smaller global precipitation sensitivities occur in higher GHG and aerosol emission scenarios. Although previous studies have applied this ESD to the multi-AOGCM mean, our surprising finding is that current AOGCMs all have the common ESD in the same direction. Different aerosol emissions lead to this ESD. The implications of the ESD of precipitation sensitivity extend far beyond climate analyses. As we show, the ESD potentially propagates into considerable biases in impact assessments of the hydrological cycle via a widely used technique, so-called pattern scaling. Since pattern scaling is essential to conducting parallel analyses across climate, impact, adaptation and mitigation scenarios in the next report from the Intergovernmental Panel on Climate Change, more attention should be paid to the ESD of precipitation sensitivity.  相似文献   

Mesoscale current fluctuations observed in the deep western North Pacific     

Shiro Imawaki  Keisuke Taira  Toshihiko Teramoto 《Journal of Oceanography》1984,40(1):39-45

A set of simultaneous long-term, deep current measurements was taken using a moored array in the mid-ocean of the western North Pacific near 30°N, 146°E. Five current meters at three stations provided good quality records over 84 days. Low-frequency current fluctuations with meridional dominance are clearly seen in the deep layer records. They are consistent with signals of a mesoscale current fluctuation which has a period of about 100 days, an east-west wave length of about 200 km, and a westward phase propagation with a speed of about 2 cm sec^–1. Bottom intensification of the east component of low-frequency current fluctuations is also observed.  相似文献   

Spatial structure within a dense bed of the brittle starOphiura sarsi (Ophiuroidea: Echinodermata) in the bathyal zone off otsuchi,Northeastern Japan     

Toshihiko Fujita  Suguru Ohta 《Journal of Oceanography》1989,45(5):289-300

Photographic observations of the brittle starOphiura sarsi were conducted at a depth of approximately 280 m in the Pacific Ocean off tsuchi, northeastern Japan. Bottom photographs showed that this ophiuroid occurred in high densities, uniformly covering the sea floor and that other megafauna was rare. The mean density and biomass of ophiuroids in the dense bed were estimated to be 373 m^–2 and 124 g m^–2, respectively. Ophiuroids comprised 99% of all megabenthic organisms in terms of number of individuals, and megafaunal assemblage of the dense bed showed very low species diversity.O. sarsi exhibited a regular spatial pattern avoiding contact with conspecific neighbors. This regular spatial pattern was disrupted by certain other organisms, around which halo-like, bare areas were observed. The size and shape of these halo-like areas varied and were apparently related to the body size and/or motility of the organisms. In the present observation areaO. sarsi covered 96% of the sea bottom, and the remaining 4% was occupied by other organisms and their halo-like bare areas.  相似文献   

Path and volume transport of the Kuroshio current in Sagami Bay and their relationship to cold water masses near Izu Peninsula     

Keisuke Taira  Toshihiko Teramoto 《Journal of Oceanography》1986,42(3):212-223

The path of the Kuroshio in Sagami Bay was surveyed through drifter tracking from Oshima-West Channel to Oshima-East Channel. A subsurface drifter with a drogue at 300 m depth flowed around Oshima from Oshima-West Channel to Oshima-East Channel. A difference in flow directions between the upper and lower layers was apparent in the northwest of Oshima. Flow directions there were shown to change from north in the surface layer to east in the bottom layer, and this was confirmed with moored currentmeters.A profile of northward current velocity was estimated from measurements in six layers with currentmeters deployed in the Oshima-West Channel. The profile shows a core of northward flow along the eastern bottom slope and a weak southward flow along the western bottom slope. Volume transport of the Kuroshio into Sagami Bay was estimated to be 1.8×10⁶m³sec^–1 from the profile.Long-term current measurement showed that southward flows were observed in Oshima-West Channel in July 1977, May 1978 and April 1979. Cold or warm water masses appearing south of the Izu Peninsula are suggested to have caused the changes.Displacement of the cold water mass in July 1977 is discussed on the basis of current measurements and offshore oceanographic conditions.  相似文献   

Concentrations of 222 Rn, Its Short-Lived Daughters And 212 Pb And Their Ratios Under Complex Atmospheric Conditions And Topography     

Toshio Kataoka  Eiji Yunoki  Mitsuo Shimizu  Tadashige Mori  Osamu Tsukamoto  Satoshi Takahashi  Hironori Fudeyasu  Yukitaka Ohashi  Ken Sahashi  Toshihiko Maitani  Koh'ichi Miyashita  Toru Iwata  Takayuki Sasaki  Yoko Fujikawa  Akira Kudo  Roger H. Shaw 《Boundary-Layer Meteorology》2003,107(1):219-249

Atmospheric activity concentrations of ²¹²Pb and short-lived ²²²Rndaughters, together with meteorological elements, have been observed continuously atthree sites at Kamisaibara Village in Japan. In addition, atmospheric activity concentrationof ²²²Rn, equilibrium-equivalent concentration of ²²²Rn and conditionsof the lower atmosphere were observed for three intensive observation periods at Akawase,one of the three sites in Kamisaibara Village. The equilibrium-equivalent concentration of²²²Rn is almost the same as the atmospheric activity concentration of short-lived²²²Rn daughters.The activity concentrations of ²¹²Pb and the short-lived ²²²Rn daughtersand their ratio were low in the daytime owing to convective mixing, and high at nightowing to the surface-based inversion during periods of no precipitation. Their variationshave several patterns corresponding to the scale of the drainage wind or weak mixing.Mechanical mixing due to strong winds through both day and night during the first andsecond observation periods made the atmospheric activity concentrations of ²¹²Pb and the short-lived ²²²Rn daughters continuously low. However, their ratios werecontinuously high during the first period yet continuously low during the second period.This difference can be explained by the effect ofextraction of ²²⁰Rn and ²²²Rndue to strong winds and snow cover. There were also cases in which the ratio of theatmospheric activity concentration of ²¹²Pb to that of the short-lived ²²²Rndaughters at night was equal to or less than the ratio in the daytime. Thisinverse trend, asin the periods of no precipitation mentioned above, is considered to be due to near-neutralconditions on these nights.We find a difference in the ratio of the equilibrium-equivalent concentration of²²²Rn (the activity concentration of short-lived ²²²Rn daughters) tothe activity concentration of ²²²Rn during the first observation period and thatduring the second. The difference can be explained by snow cover on the ground. Wealso find differences among the ratios of the activity concentration of the short-lived²²²Rn daughters to that of ²²²Rn during the three observation periods.These differences can be explained by the submergence of paddy fields.  相似文献