Projected 21st century climate change on snow conditions over Shasta Dam watershed by means of dynamical downscaling          下载免费PDF全文

Toan Trinh  M. Levent Kavvas  Kei Ishida  Kara Carr  Noriaki Ohara 《水文研究》2017,31(16):2887-2901

Snow is an important component of the Earth's climate system and is particularly vulnerable to global warming. It has been suggested that warmer temperatures may cause significant declines in snow water content and snow cover duration. In this study, snowfall and snowmelt were projected by means of a regional climate model that was coupled to a physically based snow model over Shasta Dam watershed to assess changes in snow water content and snow cover duration during the 21st century. This physically based snow model requires both physical data and future climate projections. These physical data include topography, soils, vegetation, and land use/land cover, which were collected from associated organizations. The future climate projections were dynamically downscaled by means of the regional climate model under 4 emission scenarios simulated by 2 general circulation models (fifth‐generation of the ECHAM general circulation model and the third‐generation atmospheric general circulation model). The downscaled future projections were bias corrected before projecting snowfall and snowmelt processes over Shasta Dam watershed during 2010–2099. This study's results agree with those of previous studies that projected snow water equivalent is decreasing by 50–80% whereas the fraction of precipitation falling as snowfall is decreasing by 15% to 20%. The obtained projection results show that future snow water content will change in both time and space. Furthermore, the results confirm that physical data such as topography, land cover, and atmospheric–hydrologic data are instrumental in the studies on the impact of climate change on the water resources of a region.  相似文献   

El Niño-related sea surface elevation and ocean bottom pressure enhancement associated with the retreat of the Oyashio southeast of Hokkaido,Japan     

Hasegawa  Takuya  Nagano  Akira  Matsumoto  Hiroyuki  Ariyoshi  Keisuke  Wakita  Masahide 《Marine Geophysical Researches》2019,40(4):505-512

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Observations of Fractures Induced by Hydraulic Fracturing in Anisotropic Granite     

Youqing Chen  Yuya Nagaya  Tsuyoshi Ishida 《Rock Mechanics and Rock Engineering》2015,48(4):1455-1461

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The detectability of shallow slow earthquakes by the Dense Oceanfloor Network system for Earthquakes and Tsunamis (DONET) in Tonankai district,Japan     

Keisuke Ariyoshi  Ryoko Nakata  Toru Matsuzawa  Ryota Hino  Takane Hori  Akira Hasegawa  Yoshiyuki Kaneda 《Marine Geophysical Researches》2014,35(3):295-310

In order to understand the characteristics of shallow very low-frequency (VLF) events as revealed by recent ocean-floor observation studies, we perform a trial simulation of earthquake cycles in the Tonankai district by taking the characteristics of the 1944 Tonankai earthquake and assuming that slow earthquakes occur on numerous small asperities. Our simulation results show that the increase of moment release rate of shallower VLF events in the pre-seismic stage of a megathrust earthquake is higher than that of deeper VLF events. This increase may make leveling change due to VLF swarms detectable at Dense Oceanfloor Network system for Earthquakes and Tsunamis (DONET). We also introduce the time series of hydraulic pressure data at DONET, comparing with the leveling change expected from our numerical simulation. Since leveling change due to shallower VLF swarms is so local as to be incoherent, removal of the moving-averaged data from the data stacked by four nearby observation points in the same node may be useful to detect the short-term local leveling change.  相似文献   

Cross-Validation of Open-Path and Closed-Path Eddy-Covariance Techniques for Observing Methane Fluxes     

Hiroki Iwata  Yoshiko Kosugi  Keisuke Ono  Masayoshi Mano  Ayaka Sakabe  Akira Miyata  Kenshi Takahashi 《Boundary-Layer Meteorology》2014,151(1):95-118

Methane ( ${\mathrm {CH}}_{4}$ ) fluxes observed with the eddy-covariance technique using an open-path ${\mathrm {CH}}_{4}$ analyzer and a closed-path ${\mathrm {CH}}_{4}$ analyzer in a rice paddy field were evaluated with an emphasis on the flux correction methodology. A comparison of the fluxes obtained by the analyzers revealed that both the open-path and closed-path techniques were reliable, provided that appropriate corrections were applied. For the open-path approach, the influence of fluctuations in air density and the line shape variation in laser absorption spectroscopy (hereafter, spectroscopic effect) was significant, and the relative importance of these corrections would increase when observing small ${\mathrm {CH}}_{4}$ fluxes. A new procedure proposed by Li-Cor Inc. enabled us to accurately adjust for these effects. The high-frequency loss of the open-path ${\mathrm {CH}}_{4}$ analyzer was relatively large (11 % of the uncorrected covariance) at an observation height of 2.5 m above the canopy owing to its longer physical path length, and this correction should be carefully applied before correcting for the influence of fluctuations in air density and the spectroscopic effect. Uncorrected ${\mathrm {CH}}_{4}$ fluxes observed with the closed-path analyzer were substantially underestimated (37 %) due to high-frequency loss because an undersized pump was used in the observation. Both the bandpass and transfer function approaches successfully corrected this flux loss. Careful determination of the bandpass frequency range or the transfer function and the cospectral model is required for the accurate calculation of ${\mathrm {CH}}_{4}$ fluxes with the closed-path technique.  相似文献   

Middle Eocene low-paleolatitude radiolarian evidence for the Cabog Formation,Central East Luzon,Philippine Mobile Belt     

Keisuke Ishida  Shigeyuki Suzuki  Graciano P. Yumul  Carla B. Dimalanta 《Gondwana Research》2011,19(1):61-70

The Cabog Formation, newly established herein and exposed in central East Luzon, Philippine Mobile Belt, is defined in age by the occurrence of radiolarians. The radiolarian assemblage is correlative with the middle Eocene and suggests a low paleolatitude affinity. The correlation, sedimentary environment, and the tectonic significance are discussed. The Cabog Formation is correlative with the distal part of the middle–late Eocene Caraballo Formation, which is exposed in the northeastern side of the Philippine Fault Zone. The sandstone composition and radiolarian age suggest that the Cabog Formation represents the first depositional stage in the early arc setting. The northward migration of the formation is also estimated in relation with the Philippine Sea Plate motion along the Older Philippine Fault from the equatorial area.  相似文献   

Hayabusa‐returned sample curation in the Planetary Material Sample Curation Facility of JAXA     

Toru YADA  Akio FUJIMURA  Masanao ABE  Tomoki NAKAMURA  Takaaki NOGUCHI  Ryuji OKAZAKI  Keisuke NAGAO  Yukihiro ISHIBASHI  Kei SHIRAI  Michael E. ZOLENSKY  Scott SANDFORD  Tatsuaki OKADA  Masayuki UESUGI  Yuzuru KAROUJI  Maho OGAWA  Shogo YAKAME  Munetaka UENO  Toshifumi MUKAI  Makoto YOSHIKAWA  Junichiro KAWAGUCHI 《Meteoritics & planetary science》2014,49(2):135-153

Abstract– The Planetary Material Sample Curation Facility of JAXA (PMSCF/JAXA) was established in Sagamihara, Kanagawa, Japan, to curate planetary material samples returned from space in conditions of minimum terrestrial contaminants. The performances for the curation of Hayabusa‐returned samples had been checked with a series of comprehensive tests and rehearsals. After the Hayabusa spacecraft had accomplished a round‐trip flight to asteroid 25143 Itokawa and returned its reentry capsule to the Earth in June 2010, the reentry capsule was brought back to the PMSCF/JAXA and was put to a series of processes to extract recovered samples from Itokawa. The particles recovered from the sample catcher were analyzed by electron microscope, given their ID, grouped into four categories, and preserved in dimples on quartz slide glasses. Some fraction of them has been distributed for initial analyses at NASA, and will be distributed for international announcement of opportunity (AO), but a certain fraction of them will be preserved in vacuum for future analyses.  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   

Crystallization temperature determination of Itokawa particles by plagioclase thermometry with X‐ray diffraction data obtained by a high‐resolution synchrotron Gandolfi camera     

Masahiko Tanaka  Tomoki Nakamura  Takaaki Noguchi  Aiko Nakato  Hatsumi Ishida  Toru Yada  Kei Shirai  Akio Fujimura  Yukihiro Ishibashi  Masanao Abe  Tatsuaki Okada  Munetaka Ueno  Toshifumi Mukai 《Meteoritics & planetary science》2014,49(2):237-244

The crystallization temperatures of Itokawa surface particles recovered by the space probe Hayabusa were estimated by a plagioclase geothermometer using sodic plagioclase triclinicity. The Δ131‐index required for the thermometer, which is the difference in X‐ray diffraction peak positions between the 131 and 11 reflections of plagioclase, was obtained by a high‐resolution synchrotron Gandolfi camera developed for the third generation synchrotron radiation beamline, BL15XU at SPring‐8. Crystallization temperatures were successfully determined from the Δ131‐indices for four particles. The observed plagioclase crystallization temperatures were in a range from 655 to 660 °C. The temperatures indicate crystallization temperatures of plagioclases in the process of prograde metamorphism before the peak metamorphic stage.  相似文献   

Wind and buoyancy driven intermediate-layer overturning in the Sea of Okhotsk     

Junji Matsuda  Humio Mitsudera  Tomohiro Nakamura  Keisuke Uchimoto  Takuya Nakanowatari  Naoto Ebuchi 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(9):1401-1418

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