Coupled climate-society modeling of a realistic scenario to achieve a sustainable Earth     

Motoyoshi Ikeda 《Journal of Oceanography》2011,67(1):113-126

A conceptual model was developed to project the global warming for this century. This model incorporated several important factors associated with the climate and society. Under the forcing of anthropogenic carbon dioxide, the climate system is represented by a global mean surface air temperature (SAT) and carbon storage, which is separated into the atmosphere, land and oceans. The SAT rises due to the atmospheric carbon, which is partially absorbed by the terrestrial ecosystem and the ocean. These absorption rates are reduced by the rising SAT. The anthropogenic carbon dioxide is emitted by society, which is described by global energy production (P) and energy efficiency/carbon intensity (E), yielding a rate of P/E. P consists of the energy production per capita (H) and the population (M) in developed countries and regions, P = H × M. These society components were set to grow, based on the historical record from the last 50 years, while societal incentives to reduce the growth rate H and to increase E in proportion to the increase in SAT were introduced. It is shown that, among the basic scenarios in the Special Report on Emissions Scenarios (SRES) for this century, medium-level carbon emission—where the growth rate of H is reduced by 30% and E is doubled, with 1°C of warming—could be achieved. Until the end of this century, both the terrestrial ecosystem and the oceans act as sinks. If societal incentives are eliminated, carbon emission approaches the upper limit considered in the SRES scenarios, and the terrestrial ecosystem changes into a source of carbon dioxide. Since H and E are closely related to lifestyle and technology, respectively, individuals in the developed countries are urged to change their lifestyles, and institutions need to develop low-carbon technologies and spread them to developing countries. When society achieves medium-level carbon emission for a couple of centuries, oceanic absorption was found to become more crucial than terrestrial absorption, so oceanic behavior has to be estimated more accurately.  相似文献   

Detection of the Labrador current using ice‐floe movement in synthetic aperture radar imagery and ice beacon trajectories     

M. Ikeda  C.L. Tang 《大气与海洋》2013,51(2):223-245

Abstract

Two sets of Synthetic Aperture Radar (SAR) images were collected, as part of the Labrador Ice Margin Experiment (LIMEX), over the Newfoundland Shelf on consecutive days in April 1990. Ice movement is detected from the displacement of ice floes between the two images sets and compared with ice drift data from six satellite‐tracked beacons and in situ CTD data. The ice velocity data derived from the SAR images and the beacons are used to generate a map of ice velocity vectors. A streamfunction map of ocean currents is produced by removing the direct wind‐driven component in the ice movement data, and by using an objective analysis method. The resulting flow pattern contains the offshore branch of the Labrador Current with a speed of 30 to 50 cm s^?1. The current closely follows the shelf break topography from north to south through the study area (47–50.5°N) as a continuous flow. In comparison, if the wind effect was not removed from the ice velocity data, the calculated Labrador Current north of 50°N would stray from the shelf break. The position of the current axis and the current speed derived from the ice movement data are in good agreement with the geostrophic current computed from the CTD data.  相似文献   

Imaging polarimetry of Comet 9P/Tempel before and after the Deep Impact     

Reiko Furusho  Yuji Ikeda  Wing-Huen Ip  Toshihiro Kasuga  Yusuke Sato  Ming-Shin Chang  Jun-ichi Watanabe 《Icarus》2007,190(2):454-458

The NASA's Deep Impact mission was the first impact experiment to a cometary nucleus. The target of the mission was Comet 9P/Tempel, one of the Jupiter family comets. The impact was performed on July 4th, 2005. Imaging polarimetric observations were carried out by Polarimetric Imager for COmets (PICO) mounted on the Lulin One-meter Telescope (LOT) at Lulin Observatory, Taiwan. Intensity and linear polarization degree maps were obtained on July 3-5, 2005. Impact ejecta plume was clearly recognized in the enhanced intensity map. Furthermore, arc-shaped region of high polarization was recognized in the polarization map. Dust grains in this region had larger expansion velocity than the grains which provided the brightest area in the intensity map. comparing our results with the MIR spectroscopy obtained by Subaru Telescope we conclude that very small carbonaceous grains might be responsible for the region of high polarization.  相似文献   

Genetic diversity and population structure of the golden cuttlefish,Sepia esculenta (Cephalopoda: Sepiidae) indicated by microsatellite DNA variations   总被引：1，自引：0，他引：1  

Xiaodong Zheng  Minoru Ikeda  Lingfeng Kong  Xiangzhi Lin  Qi Li  Nobuhiko Taniguchi 《Marine Ecology》2009,30(4):448-454

The golden cuttlefish, Sepia esculenta Hoyle, 1885 (Cephalopoda: Sepiidae) is a valuable and important fishery resource for China, Japan and Korea. This fishery has experienced severe population decline largely due to overexploitation in past decades. To provide guidelines for fisheries management, we estimated genetic diversity and population structure across four locations along the coast of Japan and one location in China (a total 281 individuals) using nine microsatellite DNA loci. Sepia esculenta showed high genetic variability with mean allele richness ranging from 15.8 to 21.4, and mean heterozygosity from 0.80 to 0.90. Weak but significant genetic differentiation was present and the F_ST value was 0.020 across all five populations. The useful information obtained in this study will offer insights into how to fine‐tune conservation and fishery management measures for this species and resource in the future.  相似文献   

Mesoscale variabilities and gulf stream bifurcation in the Newfoundland basin observed by the Geosat altimeter data     

M. Ikeda 《大气与海洋》2013,51(4):567-589

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Oceanic tides over the Newfoundland and Scotian Shelves from TOPEX/POSEIDON altimetry     

Guoqi Han  Moto Ikeda  Peter C. Smith 《大气与海洋》2013,51(4):589-604

Abstract

A modified response analysis in the form of an orthotide parametrization is used to derive major semi‐diurnal and diurnal tidal constituents over the Newfoundland and Scotian Shelves from TOPEX/POSEIDON altimeter data. The orthotide formulation simultaneously solves for eight major semi‐diurnal and diurnal constituents, and has an accuracy of better than ～1.5 cm for each constituent. Tidal elevations are derived from the altimeter data on the ascending and descending satellite ground tracks, and interpolated using the method of statistical interpolation. The semi‐diurnal constituents (M₂, S₂ and N₂) compare favourably with available in‐situ observations and a numerical model. The diurnals (K₁ and O₁) are not as accurate as the semi‐diurnals, especially in the nearshore environment. The paper demonstrates the ability of TOPEX/POSEIDON altimetry to provide accurate tidal data over a continental shelf.  相似文献   

Modeling seasonal variations of ocean and sea ice circulation in the Beaufort and Chukchi Seas： A model-data fusion study     

Kohei Mizobata  Walter Johnson  Koji Shimada  Moto Ikeda 《极地研究(英文版)》2008,19(2):168-184

A 3.8-kin Coupled Ice-Ocean Model （C1OM） was implemented to successfully reproduce many observed phenomena in the Beaufort and Chukchi seas, including the Bering-inflow-originated coastal current that splits into three branches： Alaska Coastal Water （ACW） , Central Channel, and Herald Valley branches. Other modeled phenomena include the Beaufort Slope Current （BSC） , the Beaufort Gyre, the East Siberian Current （ ESC）, mesoscale eddies, seasonal landfast ice, sea ice ridging, shear, and deformation. Many of these downscaling processes can only be captured by using a high-resolution CIOM, nested in a global climate model. The seasonal cycles for sea ice concentration, thickness, velocity, and other variables are well reproduced with Solid validation by satellite measurements. The seasonal cycles for upper ocean dynamics and thermodynamics are also well reproduced, which include the formation of the cold saline layer due to the injection of salt during sea ice formation, the BSC, and the subsurface upwelling in winter that brings up warm, even more saline Atlantic Water along the shelfbreak and shelf along the Beaufort coast.  相似文献   

Mass distribution of Antarctic ordinary chondrites and the estimation of the fall-to-specimen ratios     

Yukio Ikeda  Makoto Kimura 《Meteoritics & planetary science》1992,27(4):435-441

Abstract— The cumulative mass distributions (mass range > 100 g) of each type of Japanese and U.S. Antarctic ordinary chondrites are compared with those of non-Antarctic falls and those obtained from the present-day flux of meteorites. The steeper slope of the mass distribution of Antarctic chondrites is indicative of the presence of several chondrite showers. The fall-to-specimen ratio of Antarctic ordinary chondrites larger than 100 g is about 1:2, indicating that half of them are shower components. The fall-to-specimen ratios of each group range from 1:1 to 1:6; those of the Japanese and U.S. Antarctic meteorite collections are 1:1 to 1:2 and 1:4 for H chondrites, 1:1 to 1:2 and 1:2 for L chondrites, and 1:2 and 1:6 for LL chondrites, indicating that the Japanese collection includes less abundant shower components than the U.S. collection. The fall-to-specimen ratios of each H4-6 and L4-6 type range from 1:1 to 1:4, and U.S. H6 and Japanese H4 have the low ratios of 1:4.  相似文献   

Petrology and mineralogy of the Yamato-86751 CV3 chondrite     

Toshio Murakami  Yukio Ikeda 《Meteoritics & planetary science》1994,29(3):397-409

Abstract— The Y-86751 chondrite (CV3) consists of fine-grained Ca- and Al-rich inclusions (CAIs), amoeboid olivine inclusions (AOIs), spinel-rich inclusions, chondrules with and without dark rims, dark inclusions, isolated minerals, metal-sulfide aggregates, and matrix. Olivines in chondrules without dark rims and AOIs coexist with magnetite and show strong zoning from a magnesian core to a ferroan rim. Spinels in spinel-rich inclusions show similar zoning. This zoning seems to be caused by exchange reaction of olivine and spinel with an oxidized nebular gas prior to the accretion onto the parent body, and the Mg/Fe diffusion in olivines and spinels took place at a temperature of about 830–860 K. At the same time, enstatite in chondrules without dark rims was replaced by ferroan olivine at the grain boundaries. This feature suggests that chondrules without dark rims, fine-grained CAIs, spinel-rich inclusions, and AOIs have experienced oxidation in an oxidizing nebular gas. The oxygen fugacity of the oxidized nebular gas was >10^?27.3 bars at about 830 K, being more than 10⁴x larger than that of the canonical nebular gas. Magnetite occurs in the Y-86751 matrix in close association with Ni-rich taenite and Co-rich metal, and it was produced under a condition with the oxygen fugacity of ～10^?38 bars at a temperature of about 620–650 K. On the other hand, olivines in chondrules with dark rims and dark inclusions are magnesian and rich in MnO. They do not show such strong zoning. Probably they were in equilibrium with a nebular gas under a redox condition different from the oxidized nebular gas that produced the zoned olivines in chondrules without dark rims.  相似文献   

Diffuse X-ray spectrum from 10 to 40 keV measured with rocket-borne scintillation counters     

Masahiko Ikeda 《Astrophysics and Space Science》1975,35(2):255-268

The energy spectrum of the diffuse component of cosmic X-rays was measured with rocket-borne scintillation counters. Subtracting the environmental background unambiguously by means of the shutter method, the absolute values of the cosmic X-ray flux are obtained in a few keV band from 10 to 40 keV. The result indicates that the energy spectrum sharply changes its slope around 20–30 keV. Some trial functions for the spectrum are compared with our result; among them a thermal bremsstrahlung spectrum and a two-slope power law spectrum seem to fit very well. The former needs, however, another origin of X-rays in the lower and higher energy regions. ‘Sharpness’ of the break in the case of the latter is discussed, including a data point in high energy side from a balloon experiment. The acceptable range of the spectral index in the high energy side is 2.3–2.6, that of the break energy is 20–30 keV and the corresponding transition width is smaller than 50 keV, if the confidence level is to be better than 5%. Non-thermal X-ray generation due to the inverse Compton effect does not reproduce the X-ray spectrum, even if the electron spectrum shows a sharp break. Bremsstrahlung with the non-thermal electrons or protons with a sharp cut in the low energy side of the spectrum can reproduce our result, though such a cut seems unrealistic. Our result may suggest that current theories on the origin of the diffuse X-rays have to be revised.  相似文献