Orbit determination of the SELENE satellites using multi-satellite data types and evaluation of SELENE gravity field models   总被引：1，自引：0，他引：1  

S. Goossens  K. Matsumoto  D. D. Rowlands  F. G. Lemoine  H. Noda  H. Araki 《Journal of Geodesy》2011,85(8):487-504

The SELENE mission, consisting of three separate satellites that use different terrestrial-based tracking systems, presents a unique opportunity to evaluate the contribution of these tracking systems to orbit determination precision. The tracking data consist of four-way Doppler between the main orbiter and one of the two sub-satellites while the former is over the far side, and of same-beam differential VLBI tracking between the two sub-satellites. Laser altimeter data are also used for orbit determination. The contribution to orbit precision of these different data types is investigated through orbit overlap analysis. It is shown that using four-way and VLBI data improves orbit consistency for all satellites involved by reducing peak values in orbit overlap differences that exist when only standard two-way Doppler and range data are used. Including laser altimeter data improves the orbit precision of the SELENE main satellite further, resulting in very smooth total orbit errors at an average level of 18 m. The multi-satellite data have also resulted in improved lunar gravity field models, which are assessed through orbit overlap analysis using Lunar Prospector tracking data. Improvements over a pre-SELENE model are shown to be mostly in the along-track and cross-track directions. Orbit overlap differences are at a level between 13 and 21 m with the SELENE models, depending on whether 1-day data overlaps or 1-day predictions are used.  相似文献   

An emission pathway for stabilization at 6?Wm?2 radiative forcing   总被引：1，自引：0，他引：1  

Toshihiko Masui  Kenichi Matsumoto  Yasuaki Hijioka  Tsuguki Kinoshita  Toru Nozawa  Sawako Ishiwatari  Etsushi Kato  P. R. Shukla  Yoshiki Yamagata  Mikiko Kainuma 《Climatic change》2011,109(1-2):59-76

Representative Concentration Pathway 6.0 (RCP6) is a pathway that describes trends in long-term, global emissions of greenhouse gases (GHGs), short-lived species, and land-use/land-cover change leading to a stabilisation of radiative forcing at 6.0 Watts per square meter (Wm^?2) in the year 2100 without exceeding that value in prior years. Simulated with the Asia-Pacific Integrated Model (AIM), GHG emissions of RCP6 peak around 2060 and then decline through the rest of the century. The energy intensity improvement rates changes from 0.9% per year to 1.5% per year around 2060. Emissions are assumed to be reduced cost-effectively in any period through a global market for emissions permits. The exchange of CO₂ between the atmosphere and terrestrial ecosystem through photosynthesis and respiration are estimated with the ecosystem model. The regional emissions, except CO₂ and N₂O, are downscaled to facilitate transfer to climate models.  相似文献   

The RCP greenhouse gas concentrations and their extensions from 1765 to 2300   总被引：16，自引：2，他引：14  

Malte Meinshausen  S. J. Smith  K. Calvin  J. S. Daniel  M. L. T. Kainuma  J-F. Lamarque  K. Matsumoto  S. A. Montzka  S. C. B. Raper  K. Riahi  A. Thomson  G. J. M. Velders  D.P. P. van Vuuren 《Climatic change》2011,109(1-2):213-241

We present the greenhouse gas concentrations for the Representative Concentration Pathways (RCPs) and their extensions beyond 2100, the Extended Concentration Pathways (ECPs). These projections include all major anthropogenic greenhouse gases and are a result of a multi-year effort to produce new scenarios for climate change research. We combine a suite of atmospheric concentration observations and emissions estimates for greenhouse gases (GHGs) through the historical period (1750?C2005) with harmonized emissions projected by four different Integrated Assessment Models for 2005?C2100. As concentrations are somewhat dependent on the future climate itself (due to climate feedbacks in the carbon and other gas cycles), we emulate median response characteristics of models assessed in the IPCC Fourth Assessment Report using the reduced-complexity carbon cycle climate model MAGICC6. Projected ??best-estimate?? global-mean surface temperature increases (using inter alia a climate sensitivity of 3°C) range from 1.5°C by 2100 for the lowest of the four RCPs, called both RCP3-PD and RCP2.6, to 4.5°C for the highest one, RCP8.5, relative to pre-industrial levels. Beyond 2100, we present the ECPs that are simple extensions of the RCPs, based on the assumption of either smoothly stabilizing concentrations or constant emissions: For example, the lower RCP2.6 pathway represents a strong mitigation scenario and is extended by assuming constant emissions after 2100 (including net negative CO₂ emissions), leading to CO₂ concentrations returning to 360 ppm by 2300. We also present the GHG concentrations for one supplementary extension, which illustrates the stringent emissions implications of attempting to go back to ECP4.5 concentration levels by 2250 after emissions during the 21^st century followed the higher RCP6 scenario. Corresponding radiative forcing values are presented for the RCP and ECPs.  相似文献   

Effect of hydrogen on the melting temperature of FeS at high pressure: Implications for the core of Ganymede     

Yuki Shibazaki  Eiji Ohtani  Hidenori Terasaki  Ryuji Tateyama  Tatsuya Sakamaki  Taku Tsuchiya  Ken-ichi Funakoshi 《Earth and Planetary Science Letters》2011,301(1-2):153-158

We have carried out in situ X-ray diffraction experiments on the FeS–H system up to 16.5 GPa and 1723 K using a Kawai-type multianvil high-pressure apparatus employing synchrotron X-ray radiation. Hydrogen was supplied to FeS from the thermal decomposition of LiAlH₄, and FeSH_x was formed at high pressures and temperatures. The melting temperature and phase relationships of FeSH_x were determined based on in situ powder X-ray diffraction data. The melting temperature of FeSH_x was reduced by 150–250 K comparing with that of pure FeS. The hydrogen concentration in FeSH_x was determined to be x = 0.2–0.4 just before melting occurred between 3.0 and 16.5 GPa. It is considered that sulfur is the major light element in the core of Ganymede, one of the Galilean satellites of Jupiter. Although the interior of Ganymede is differentiated today, the silicate rock and the iron alloy mixed with H₂O, and the iron alloy could react with H₂O (as ice or water) or the hydrous silicate before the differentiation occurred in an early period, resulting in a formation of iron hydride. Therefore, Ganymede's core may be composed of an Fe–S–H system. According to our results, hydrogen dissolved in Ganymede's core lowers the melting temperature of the core composition, and so today, the core could have solid FeSH_x inner core and liquid FeH_x–FeSH_x outer core and the present core temperature is considered to be relatively low.  相似文献   

Flood monitoring, mapping and assessing capabilities using RADARSAT remote sensing, GIS and ground data for Bangladesh   总被引：3，自引：1，他引：2  

Roxana Hoque  Daichi Nakayama  Hiroshi Matsuyama  Jun Matsumoto 《Natural Hazards》2011,57(2):525-548

Remote sensing is the most practical method available to managers of flood-prone areas for quantifying and mapping flood impacts. This study explored large inundation areas in the Maghna River Basin, around the northeastern Bangladesh, as determined from passive sensor LANDSAT data and the cloud-penetrating capabilities of the active sensors of the remote imaging microwave RADARSAT. This study also used passive sensor LANDSAT wet and dry images for the year 2000. Spatial resolution was 30 m by 30 m for comparisons of the inundation area with RADARSAT images. RADARSAT images with spatial resolution of 50 m by 50 m were used for frequency analysis of floods from 2000 to 2004. Time series images for 2004 were also used. RADARSAT remote sensing data, GIS data, and ground data were used for the purpose of flood monitoring, mapping and assessing. A supervised classification technique was used for this processing. They were processed for creating a maximum water extent map and for estimating inundation areas. The results of this study indicated that the maximum extent of the inundation area as estimated using RADARSAT satellite imaging was about 29, 900.72 km² in 2004, which corresponded well with the heavy rainfall around northeast region, as seen at the Bhairab Bazar station and with the highest water level of the Ganges–Brahmaputra–Meghna (GBM) Rivers. A composite of 5 years of RADARSAT inundation maps from 2000 to 2004, GIS data, and damage data, was used to create unique flood hazard maps. Using the damage data for 2004 and the GIS data, a set of damage maps was also created. These maps are expected to be useful for future planning and flood disaster management. Thus, it has been demonstrated that RADARSAT imaging data acquired over the Bangladesh have the ability to precisely assess and clarify inundation areas allowing for successful flood monitoring, mapping and disaster management.  相似文献   

http://www.sciencedirect.com/science/article/pii/S167498711000037X     

Shuangmeng Zhai  Eiji Ito 《地学前缘(英文版)》2011,2(1):101-106

The tried and tested multianvil apparatus has been widely used for high-pressure and high-temperature experimental studies in Earth science. As a result, many important results have been obtained for a better understanding of the components, structure and evolution of the Earth. Due to the strength limitation of materials, the attainable multianvil pressure is generally limited to about 30 GPa (corresponding to about 900 km of the depth in the Earth) when tungsten carbide cubes are adopted as second-stage anvils. Compared with tungsten carbide, the sintered diamond is a much harder material. The sintered diamond cubes were introduced as second-stage anvils in a 6–8 type multianvil apparatus in the 1980s, which largely enhanced the capacity of pressure generation in a large volume press. With the development of material synthesis and processing techniques, a large sintered diamond cube (14 mm) is now available. Recently, maximum attainable pressures reaching higher than 90 GPa (corresponding to about 2700 km of the depth in the Earth) have been generated at room temperature by adopting 14-mm sintered diamond anvils. Using this technique, a few researches have been carried out by the quenched method or combined with synchrotron radiation in situ observation. In this paper we review the properties of sintered diamond and the evolution of pressure generation using sintered diamond anvils. As-yet unsolved problems and perspectives for uses in Earth Science are also discussed.  相似文献   

Investigation of cutting methods for small samples of Hayabusa and future sample return missions     

Masayuki Uesugi  Ryo Noguchi  Tooru Matsumoto  Junya Matsuno  Takashi Nagano  Akira Tsuchiyama  Shigenori Harada  Kaori Yokoyama  Yoshiaki Yodo  Noboru Takeda  Toru Yada  Shogo Yakame  Yuzuru Karouji  Yukihiro Ishibashi  Masanao Abe  Tatsuaki Okada  Akio Fujimura  Mitsuru Ebihara  Fumio Kitajima  Keisuke Nagao  Tomoki Nakamura  Hiroshi Naraoka  Takaaki Noguchi  Ryuji Okazaki  Hisayoshi Yurimoto 《Meteoritics & planetary science》2014,49(7):1186-1201

We report the investigation of cutting methods for Hayabusa samples. The purpose of our study is to explore the possibility of applying multiple analyses to a single particle effectively. We investigated the cutting performance of a blade dicing saw, laser, focused ion beam (FIB), and physical breaking by microindenter. Cutting performance was examined by estimating the aspect ratio of the cut slit, i.e., depth over width of the slit. We also investigated the possible contamination and sample damage by cutting. The result of the investigation shows that we can cut the samples from <50 μm to 500 μm using those methods with aspect ratios from 10 to 20, although they would introduce some contamination or damage to the samples. Our investigations also provide an important basis for the analysis of samples obtained by future sample return missions.  相似文献   

Three‐dimensional microstructure of samples recovered from asteroid 25143 Itokawa: Comparison with LL5 and LL6 chondrite particles     

Akira Tsuchiyama  Masayuki Uesugi  Kentaro Uesugi  Tsukasa Nakano  Ryo Noguchi  Toru Matsumoto  Junya Matsuno  Takashi Nagano  Yuta Imai  Akira Shimada  Akihisa Takeuchi  Yoshio Suzuki  Tomoki Nakamura  Takaaki Noguchi  Masanao Abe  Toru Yada  Akio Fujimura 《Meteoritics & planetary science》2014,49(2):172-187

In this study, the three‐dimensional (3‐D) microstructure of 48 Itokawa regolith particles was examined by synchrotron microtomography at SPring‐8 during the preliminary examination of Hayabusa samples. Moreover, the 3‐D microstructure of particles collected from two LL6 chondrites (Ensisheim and Kilabo meteorites) and an LL5 chondrite (Tuxtuac meteorite) was investigated by the same method for comparison. The modal abundances of minerals, especially olivine, bulk density, porosity, and grain size are similar in all samples, including voids and cracks. These results show that the Itokawa particles, which are surface materials from the S‐type asteroid Itokawa, are consistent with the LL chondrite materials in terms of not only elemental and isotopic composition of the minerals but also 3‐D microstructure. However, we could not determine whether the Itokawa particles are purely LL5, LL6, or a mixture of the two. No difference between the particles collected from Rooms A and B of the sample chamber, corresponding to the sampling sequence of the spacecraft's second and first touchdowns, respectively, was detected because of the statistically small amount of particles from Room B.  相似文献   

Degradation of algal lipids by deep-sea benthic foraminifera: An in situ tracer experiment     

Hidetaka Nomaki  Naohiko Ohkouchi  Petra Heinz  Hisami Suga  Yoshito Chikaraishi  Nanako O. Ogawa  Kouhei Matsumoto  Hiroshi Kitazato 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(9):1488-1503

We conducted an in situ feeding experiment using ¹³C-labeled unicellular algae in Sagami Bay, Japan (water depth, 1450 m), in order to understand the fate of lipid compounds in phytodetritus at the deep-sea floor. We examined the incorporation of excess ¹³C into lipid compounds extracted from bulk sediments and benthic foraminiferal cells. ¹³C-enriched fatty acids derived from ¹³C-labeled algae were exponentially degraded during 6 days of incubation in the sediment. Subsequent enrichments in ¹³C in sedimentary n-C_15, anteiso-C₁₇, and C₁₇ fatty acids indicated the microbial degradation of algal material and production of bacterial biomass in the sediment. We observed the incorporation of ¹³C-labeled algal phytol and fatty acids into foraminiferal cells. The compositions of ¹³C-labeled algal lipids in foraminiferal cells were different from those in the bulk sediments, indicating that foraminiferal feeding and digestion influenced the lipid distribution in the sediments. Furthermore, some sterols in Globobulimina affinis (e.g., 24-ethylcholesta-5,22-dien-3β-ol, 24-ethylcholest-5-en-3β-ol, and 23,24-dimethylcholesta-5,22E-dien-3β-ol) were newly produced via the modification of dietary algal sterols within 4–6 days. In addition to the effects of bacteria, feeding by benthic foraminifera can result in a significant reorganization of the composition of organic matter and influence benthic food webs and carbon cycling at the deep-sea floor.  相似文献   

A simplified analysis method for piled raft foundations in non‐homogeneous soils     

Pastsakorn Kitiyodom  Tatsunori Matsumoto 《国际地质力学数值与分析法杂志》2003,27(2):85-109

A simplified method of numerical analysis based on elasticity theory has been developed for the analysis of axially and laterally loaded piled raft foundations embedded in non‐homogeneous soils and incorporated into a computer program “PRAB”. In this method, a hybrid model is employed in which the flexible raft is modelled as thin plates and the piles as elastic beams and the soil is treated as springs. The interactions between structural members, pile–soil–pile, pile–soil–raft and raft–soil–raft interactions, are approximated based on Mindlin's solutions for both vertical and lateral forces with consideration of non‐homogeneous soils. The validity of the proposed method is verified through comparisons with some published solutions for single piles, pile groups and capped pile groups in non‐homogeneous soils. Thereafter, the solutions from this approach for the analysis of axially and laterally loaded 4‐pile pile groups and 4‐pile piled rafts embedded in finite homogeneous and non‐homogeneous soil layers are compared with those from three‐dimensional finite element analysis. Good agreement between the present approach and the more rigorous finite element approach is demonstrated. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献