Temperature scaling pattern dependence on representative concentration pathway emission scenarios
A letter     

Yasuhiro Ishizaki  Hideo Shiogama  Seita Emori  Tokuta Yokohata  Toru Nozawa  Tomoo Ogura  Manabu Abe  Masakazu Yoshimori  Kiyoshi Takahashi 《Climatic change》2012,112(2):535-546

To preserve consistency among developed emission scenarios, the scenarios used in climate modeling, and the climate scenarios available for impact research, the pattern scaling technique is useful technique. The basic assumption of pattern scaling is that the spatial response pattern per 1 K increase in the global mean surface air temperature (SAT) (scaling pattern) is the same among emission scenarios, but this assumption requires further validation. We therefore investigated the dependence of the scaling pattern of the annual mean SAT on GHGs emission scenarios of representative concentration pathways (RCP) and the causes of that dependence using the Model for Interdisciplinary research on Climate 5 developed by Japanese research community. In particular, we focused on the relationships of the dependency with effects of aerosols and Atlantic meridional overturning circulation. We found significant dependencies of the scaling pattern on emission scenarios at middle and high latitudes of the Northern Hemisphere, with differences of >15 % over parts of East Asia, North America, and Europe. Impact researchers should take into account those dependencies that seriously affect their research. The mid-latitude dependence is caused by differences in sulfate aerosol emissions per 1 K increase in the global mean SAT, and the high-latitude dependence is mainly caused by nonlinear responses of sea ice and ocean heat transport to global warming. Long-term trends in land-use and land-cover changes did not significantly affect the scaling pattern of annual mean SAT, but they might have an effect at different timescales.  相似文献   

Elemental and isotope behavior of macromolecular organic matter from CM chondrites during hydrous pyrolysis     

Yasuhiro OBA  Hiroshi NARAOKA 《Meteoritics & planetary science》2009,44(7):943-953

Abstract— A new insight into carbon and hydrogen isotope variations of insoluble organic matter (IOM) is provided from seven CM chondrites, including Murchison and six Antarctic meteorites (Y‐791198, Y‐793321, A‐881280, A‐881334, A‐881458 and B‐7904) as well as Murchison IOM residues after hydrous pyrolysis at 270–330 °C for 72 h. Isotopic compositions of bulk carbon (δ¹³C_bulk) and hydrogen (δD) of the seven IOMs vary widely, ranging from ?15.1 to ?7.6%₀ and +133 to +986%₀, respectively. Intramolecular carboxyl carbon (δ13C_COOH) is more enriched in ¹³C by 7.5. 11%₀ than bulk carbon. After hydrous pyrolysis of Murchison IOM at 330 °C, H/C ratio, δ13C_bulk, δ13C_COOH, and δD values decrease by up to 0.31, 3.5%₀, 5.5%₀, and 961%₀, respectively. The O/C ratio increases from 0.22 to 0.46 at 270 °C and to 0.25 at 300 °C, and decreases to 0.10 at 330 °C. δ13C_bulk‐δD cross plot of Murchison IOM and its pyrolysis residues shows an isotopic sequence. Of the six Antarctic IOMs, A‐881280, A‐881458, Y‐791198 and B‐7904 lie on or near the isotopic sequence depending on the degree of hydrous and/or thermal alteration, while A‐881334 and Y‐793321 consist of another distinct isotope group. A δ13C_bulk‐δ13C_COOH cross‐plot of IOMs, including Murchison pyrolysis residues, has a positive correlation between them, implying that the oxidation process to produce carboxyls is similar among all IOMs. These isotope distributions reflect various degree of alteration on the meteorite parent bodies and/or difference in original isotopic compositions before the parent body processes.  相似文献   

Simultaneous MITSuME g'R_CI_C monitoring of S5 0716+714     

C. S. Stalin  Koji. S. Kawabata  Makoto Uemura  Michitoshi Yoshida  Nobuyuki Kawai  Kenshi Yanagisawa  Yasuhiro Shimizu  Daisuke Kuroda  Shogo Nagayama  Hiroyuki Toda 《Monthly notices of the Royal Astronomical Society》2009,399(3):1357-1366

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An Early Albian Arctic-type ammonite Arcthoplites from Hokkaido,northern Japan,and its paleobiogeographic and paleoclimatological implications     

Yasuhiro Iba 《Journal of Asian Earth Sciences》2009,34(1):46-50

An Early Albian Arctic-type ammonite Arcthoplites was discovered from the Kamiji Formation of the Yezo Group in the Nakagawa area, northern Hokkaido, northern Japan. This is the first reliable record of a hoplitid ammonite from Japan and clearly indicates the distribution of an Arctic fauna in the middle latitudes of the North Pacific at that time. Synchronously with the appearance of this Arctic-type ammonite, the tropical Tethyan biota (Mesogean taxa) disappeared from Hokkaido and elsewhere in the Northwest Pacific. These biogeographic changes suggest the existence of a “cooling” episode in the Early Albian North Pacific.  相似文献   

Oxygen isotope fractionation of dissolved oxygen during reduction by ferrous iron     

Yasuhiro Oba  Simon R. Poulson 《Geochimica et cosmochimica acta》2009,73(1):13-468

The oxygen isotope fractionation factor of dissolved oxygen gas has been measured during inorganic reduction by aqueous FeSO₄ at 10−54 °C under neutral (pH 7) and acidic (pH 2) conditions, with Fe(II) concentrations ranging up to 0.67 mol L⁻¹, in order to better understand the geochemical behavior of oxygen in ferrous iron-rich groundwater and acidic mine pit lakes. The rate of oxygen reduction increased with increasing temperature and increasing Fe(II) concentration, with the pseudo-first-order rate constant k ranging from 2.3 to 82.9 × 10⁻⁶ s⁻¹ under neutral conditions and 2.1 to 37.4 × 10⁻⁷ s⁻¹ under acidic conditions. The activation energy of oxygen reduction was 30.9 ± 6.6 kJ mol⁻¹ and 49.7 ± 13.0 kJ mol⁻¹ under neutral and acidic conditions, respectively. Oxygen isotope enrichment factors (ε) become smaller with increasing temperature, increasing ferrous iron concentration, and increasing reaction rate under acidic conditions, with ε values ranging from −4.5‰ to −11.6‰. Under neutral conditions, ε does not show any systematic trends vs. temperature or ferrous iron concentration, with ε values ranging from −7.3 to −10.3‰. Characterization of the oxygen isotope fractionation factor associated with O₂ reduction by Fe(II) will have application to elucidating the process or processes responsible for oxygen consumption in environments such as groundwater and acidic mine pit lakes, where a number of possible processes (e.g. biological respiration, reduction by reduced species) may have taken place.  相似文献   

Phase relations of iron–silicon alloys at high pressure and high temperature     

Yasuhiro Kuwayama  Toshimitsu Sawai  Kei Hirose  Nagayoshi Sata  Yasuo Ohishi 《Physics and Chemistry of Minerals》2009,36(9):511-518

The phase relations of Fe-6.4 wt% Si and Fe-9.9 wt% Si have been investigated up to 130 GPa and 2,600 K based on in situ synchrotron X-ray diffraction measurements in a laser-heated diamond-anvil cell along with chemical analysis of the quenched samples using a field-emission electron probe microanalyzer. We found that the maximum solubility of silicon in solid hcp-iron increases with increasing pressure. Linear extrapolation of the phase boundary between hcp + B2 and hcp phases for Fe-9.9 wt% Si suggests that the solid hcp-iron can include more than 9.9 wt% Si at the Earth’s inner-core conditions. If silicon is a major light element in the outer core, a substantial amount of silicon may be incorporated into the inner core during inner-core solidification.  相似文献   

A survey of organic solvent extractable metal concentrations in the bottom sediments in Osaka Bay, Japan     

Yamada M  Yamamoto K  Ushihara Y  Kawai H 《Marine pollution bulletin》2006,52(2):231-238

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An efficient time-domain soil-structure interaction analysis based on the dynamic stiffness of an unbounded soil     

Yasuhiro Hayashi  Ikuo Takahashi 《地震工程与结构动力学》1992,21(9):787-798

An approximate method and a rigorous method are presented for the time-domain soil-structure interaction analysis, both of which use the stiffness of soil obtained numerically or experimentally in the limited frequency range. In the aseismic design of a large-scale structure, the approximate and rigorous methods are intended to be used in a preliminary analysis and a detailed study, respectively. Both methods are based on the approximation that the first few terms of the Fourier or Taylor expansions of a frequency-dependent function are used. The difference lies in the number of coefficients of each series, and also in the manner in which the coefficients can be determined. In order to demonstrate the validity of the proposed methods, a soil-structure system, whose soil has a complex profile under the foundation, is analysed. The dynamic stiffness of the soil is calculated by a 3-D hybrid approach that combines the finite element method and the boundary element method. As a result, the present methods are capable of evaluating the complexity of the soil more precisely and efficiently than conventional methods.  相似文献   

Carbon isotopic composition of acetic acid generated by hydrous pyrolysis of macromolecular organic matter from the Murchison meteorite     

Yasuhiro Oba  Hiroshi Naraoka 《Meteoritics & planetary science》2006,41(8):1175-1181

Abstract— Low molecular weight monocarboxylic acids, including acetic acid, are some of the most abundant organic compounds in carbonaceous chondrites. So far, the ¹³C‐ and D‐enriched signature of water‐extractable carboxylic acids has implied an interstellar contribution to their origin. However, it also has been proposed that monocarboxylic acids could be formed by aqueous reaction on the meteorite parent body. In this study, we conducted hydrous pyrolysis of macromolecular organic matter purified from the Murchison meteorite (CM2) to examine the generation of monocarboxylic acids with their stable carbon isotope measurement. During hydrous pyrolysis of macromolecular organic matter at 270–330 °C, monocarboxylic acids with carbon numbers ranging from 2 (C₂) to 5 (C₅) were detected, acetic acid (CH₃COOH; C₂) being the most abundant. The concentration of the generated acetic acid increased with increasing reaction temperature; up to 0.48 mmol acetic acid/g macromolecular organic matter at 330 °C. This result indicates that the Murchison macromolecule has a potential to generate at least ?0.4 mg acetic acid/g meteorite, which is about four times higher than the amount of water‐extractable acetic acid reported from Murchison. The carbon isotopic composition of acetic acid generated by hydrous pyrolysis of macromolecular organic matter is ?‐27‰ (versus PDB), which is much more depleted in ¹³C than the water‐extractable acetic acid reported from Murchison. Intramolecular carbon isotope distribution shows that methyl (CH₃‐)‐C is more enriched in ¹³C relative to carboxyl (‐COOH)‐C, indicating a kinetic process for this formation. Although the experimental condition of this study (i.e., 270–330 °C for 72 h) may not simulate a reaction condition on parent bodies of carbonaceous chondrite, it may be possible to generate monocarboxylic acids at lower temperatures for a longer period of time.  相似文献   

An experimental study on Fischer‐Tropsch catalysis: Implications for impact phenomena and nebular chemistry     

Yasuhito SEKINE  Seiji SUGITA  Takafumi SHIDO  Takashi YAMAMOTO  Yasuhiro IWASAWA  Toshihiko KADONO  Takafumi MATSUI 《Meteoritics & planetary science》2006,41(5):715-729

Abstract— Fischer‐Tropsch catalysis, by which CO and H₂ are converted to CH₄ on the surface of transition metals, has been considered to be one of the most important chemical reactions in many planetary processes, such as the formation of the solar and circumplanetary nebulae, the expansion of vapor clouds induced by cometary impacts, and the atmospheric re‐entry of vapor condensate due to asteroidal impacts. However, few quantitative experimental studies have been conducted for the catalytic reaction under conditions relevant to these planetary processes. In this study, we conduct Fischer‐Tropsch catalytic experiments at low pressures (1.3 times 10^?4 bar ≤ P ≤ 5.3 times 10^?1 bar) over a wide range of H₂/CO ratios (0.25–1000) using pure iron, pure nickel, and iron‐nickel alloys. We analyze what gas species are produced and measure the CH₄ formation rate. Our results indicate that the CH₄ formation rate for iron catalysts strongly depends on both pressure and the H₂/CO ratio, and that nickel is a more efficient catalyst at lower pressures and lower H₂/CO ratios. This difference in catalytic properties between iron and nickel may come from the reaction steps concerning disproportionation of CO, hydrogenation of surface carbon, and the poisoning of the catalyst. These results suggest that nickel is important in the atmospheric re‐entry of impact condensate, while iron is efficient in circumplanetary subnebulae. Our results also indicate that previous numerical models of iron catalysis based on experimental data at 1 bar considerably overestimate CH₄ formation efficiency at lower pressures, such as the solar nebula and the atmospheric re‐entry of impact condensate.  相似文献