An overview of decadal climate predictability in a multi-model ensemble by climate model MIROC   总被引：1，自引：1，他引：0  

Yoshimitsu Chikamoto  Masahide Kimoto  Masayoshi Ishii  Takashi Mochizuki  Takashi T. Sakamoto  Hiroaki Tatebe  Yoshiki Komuro  Masahiro Watanabe  Toru Nozawa  Hideo Shiogama  Masato Mori  Sayaka Yasunaka  Yukiko Imada 《Climate Dynamics》2013,40(5-6):1201-1222

Decadal climate predictability is examined in hindcast experiments by a multi-model ensemble using three versions of the coupled atmosphere-ocean model MIROC. In these hindcast experiments, initial conditions are obtained from an anomaly assimilation procedure using the observed oceanic temperature and salinity with prescribed natural and anthropogenic forcings on the basis of the historical data and future emission scenarios in the Intergovernmental Panel of Climate Change. Results of the multi-model ensemble in our hindcast experiments show that predictability of surface air temperature (SAT) anomalies on decadal timescales mostly originates from externally forced variability. Although the predictable component of internally generated variability has considerably smaller SAT variance than that of externally forced variability, ocean subsurface temperature variability has predictive skills over almost a decade, particularly in the North Pacific and the North Atlantic where dominant signals associated with Pacific decadal oscillation (PDO) and the Atlantic multidecadal oscillation (AMO) are observed. Initialization enhances the predictive skills of AMO and PDO indices and slightly improves those of global mean temperature anomalies. Improvement of these predictive skills in the multi-model ensemble is higher than that in a single-model ensemble.  相似文献   

Assessment of digital camera-derived vegetation indices in quantitative monitoring of seasonal rice growth   总被引：4，自引：0，他引：4  

Toshihiro Sakamoto  Michio Shibayama  Akihiko Kimura  Eiji Takada 《ISPRS Journal of Photogrammetry and Remote Sensing》2011,66(6):872-882

A commercially available digital camera can be used in a low-cost automatic observation system for monitoring crop growth change in open-air fields. We developed a prototype Crop Phenology Recording System (CPRS) for monitoring rice growth, but the ready-made waterproof cases that we used produced shadows on the images. After modifying the waterproof cases, we repeated the fixed-point camera observations to clarify questions regarding digital camera-derived vegetation indices (VIs), namely, the visible atmospherically resistant index (VARI) based on daytime normal color images (RGB image) and the nighttime relative brightness index (NRBI_NIR) based on nighttime near infrared (NIR) images. We also took frequent measurements of agronomic data such as plant length, leaf area index (LAI), and aboveground dry matter weight to gain a detailed understanding of the temporal relationship between the VIs and the biophysical parameters of rice. In addition, we conducted another nighttime outdoor experiment to establish the link between NRBI_NIR and camera-to-object distance. The study produced the following findings. (1) The customized waterproof cases succeeded in preventing large shadows from being cast, especially on nighttime images, and it was confirmed that the brightness of the nighttime NIR images had spatial heterogeneity when a point light source (flashlight) was used, in contrast to the daytime RGB images. (2) The additional experiment using a forklift showed that both the ISO sensitivity and the calibrated digital number of the NIR (cDN_NIR) had significant effects on the sensitivity of NRBI_NIR to the camera-to-object distance. (3) Detailed measurements of a reproductive stem were collected to investigate the connection between the morphological feature change caused by the panicle sagging process and the downtrend in NRBI_NIR during the reproductive stages. However, these agronomic data were not completely in accord with NRBI_NIR in terms of the temporal pattern. (4) The time-series data for the LAI, plant length, and aboveground dry matter weight could be well approximated by a sigmoid curve based on NRBI_NIR and VARI. The results confirmed that NRBI_NIR was more sensitive to all of the agronomic data for overall season, including the early reproductive stages. VARI had an especially high correlation with LAI, unless yellow panicles appeared in the field of view.  相似文献   

Crack growth in Westerly granite during a cyclic loading test     

Youqing Chen  Kota Watanabe  Hiromu Kusuda  Eishi Kusaka  Mamoru Mabuchi 《Engineering Geology》2011,117(3-4):189-197

To examine the fatigue process of granite, cylindrical Westerly granite specimens, 10 mm in diameter and 20 mm in length, were subjected to a cyclic loading test under uniaxial compression with a maximum of 140 MPa at room temperature, and crack growth patterns within them were analyzed by microscopic observation and image analysis techniques. The fatigue process is divided into three characteristic stages; a primary stage in which the upper peak strain increases at a decelerating rate (stage I), a second stage with linearly slight increasing rate of strain following stage I (stage II), and the third and final stage in which the upper peak strain increases at an accelerating rate and culminates in specimen failure (stage III). A series of prefailure specimens, of which the stage in the fatigue process was decided by monitoring the strain behavior during the test, were retrieved. In addition, these specimens were compared with specimens stressed to close to the breaking strength by monotonic compression to examine the characteristic features of fatigue. The fluorescent method was applied to identify microcracks within the specimens. The advantage of this method is to provide quick and accurate identification of microcracks with an optical microscope. Microcracks are detected based on a marked difference in brightness under ultraviolet light irradiation because they are fully filled with acrylic resin mixed with a fluorescent substance in advance. Thin sections, including the axis of the specimen, 10 × 20 mm, were prepared for detailed observation after the pretreatment of the method.The results were as follows. At the initial degradation stage, distinguishing crack growth was identified in quartz grains. It is estimated that the slowdown of the strain growth rate at this stage was caused by the decrease in crack growth, that is, the portions with cracking potentiality were damaged at the first or early loading, and no further damage occurred immediately following the first damage. At the second stage, no significant crack growth in quartz grains was identified. On the other hand, in feldspar grains, development of cracks in a preferential direction, parallel to the loading direction, was observed. However, they did not grow into intergranular cracks by cutting across the grain boundaries during this stage. Consequently, it was found that a gradual progress of microcracks within feldspar grains was dominant during the second stage, and this is because the strain growth rate was in a steady and long state. At the final accelerated stage, many intergranular cracks running parallel to the loading direction were identified. It is obvious that these long cracks were formed mainly by the linking and growth of the intragranular cracks in feldspars, which were generated during the former stages. Their formation takes the fatigue process from the second stage to the final stage with a sharp increase in strain, and their further development seemed to lead the whole specimen to ultimate fatigue failure.  相似文献   

Mechanisms of enhanced ocean surface warming in the Kuroshio region for 1951–2010     

Toda  Masaki  Watanabe  Masahiro 《Climate Dynamics》2020,54(9):4129-4145

Climate Dynamics - Since the early twentieth century, observations have shown that the ocean surface has warmed almost globally, but the rate of sea surface temperature (SST) rise in the Kuroshio...  相似文献   

Wakefieldite‐(Nd), a New Neodymium Vanadate Mineral in the Arase Stratiform Ferromanganese Deposit,Kochi Prefecture,Japan     

Takeru Moriyama  Ritsuro Miyawaki  Kazumi Yokoyama  Satoshi Matsubara  Hideo Hirano  Hiroyasu Murakami  Yasushi Watanabe 《Resource Geology》2011,61(1):101-110

Wakefieldite‐(Nd), NdVO₄, is a new mineral found from the Arase stratiform ferromanganese deposit in Kochi Prefecture, Shikoku Island, Japan. It is the Nd‐dominant analogue of wakefieldite‐(Y) and wakefieldite‐(Ce). The ferromanganese ore specimen mainly consists of hematite and caryopilite, and wakefieldite‐(Nd) is typically enclosed in caryopilite. Wakefieldite‐(Nd) is tetragonal, I4₁/amd, a = 7.338(16) Å, c = 6.509(19) Å, V = 350.5(18) ų, Z = 4. The four strongest lines in the X‐ray diffraction pattern [d(Å), I/I₀, hkl] using a Gandolfi camera are (3.67, 100, 200); (2.74, 51, 112); (4.84, 27, 101) and (1.89, 25, 312). Chemical composition of wakefieldite‐(Nd) are V₂O₃ 35.25, As₂O₃ 0.93, SiO₂ 0.14, MnO 1.45, Fe₂O₃ 0.41, Y₂O₃ 2.87, La₂O₃ 7.61, Ce₂O₃ 7.37, Pr₂O₃ 6.04, Nd₂O₃ 26.79, Sm₂O₃ 4.41, Eu₂O₃ 1.36, Gd₂O₃ 3.41, Tb₂O₃ 0.22, Dy₂O₃ 1.41, Er₂O₃ 0.10, total 99.77 wt.%. The empirical formula is (Nd_0.403La_0.118Ce_0.114Pr_0.093Y_0.064Sm_0.064Mn_0.052Gd_0.048Eu_0.020Dy_0.019Fe_0.013Tb_0.003Er_0.001)_1.012(V_0.981As_0.020Si_0.006)_1.007O₄ on the basis of O = 4. The calculated density is 4.782 g/cm³. Microtexture and co‐existing relationship between wakefieldite‐(Nd) and caryopilite suggest that recrystallization and dehydration of Fe‐ and Mn‐oxyhydroxide led to the generation of hematite, caryopilite, rhodochrosite and wakefieldite‐(Nd) by the metamorphism during the accretion of the host unit of the Arase deposit. Chondrite‐normalized REE pattern of the host ferromanganese ore, which is regarded as oceanic metalliferous sediment in origin, shows negative Ce anomaly. Chemical composition of wakefieldite‐(Nd) reflects Ce‐depleted bulk composition of REE‐enriched ferromanganese ore.  相似文献   

A powerful new infrared array camera for the NASA Infrared Telescope Facility     

Mark Shure  D. W. Toomey  John Rayner  P. Onaka  A. Denault  W. Stahlberger  D. Watanabe  K. Criez  L. Robertson  D. Cook  M. Kidger 《Experimental Astronomy》1994,3(1-4):239-242

We have just finished building a 1.0–5.5 m infrared array camera for the NASA Infrared Telescope Facility based upon the SBRC 256×256 InSb array. After a brief overview of the capabilities of the camera (named NSFCAM), we present some of the first images obtained with this new camera, including results obtained with our realtime shift & add speckle imaging mode.  相似文献   

Relation between the concentrations of DMS in surface seawater and air in the temperate North Pacific region     

Shuichi Watanabe  Hiroshi Yamamoto  Shizuo Tsunogai 《Journal of Atmospheric Chemistry》1995,22(3):271-283

The concentrations of DMS were simultaneously measured in both water and air at the sea surface on board a vessel during a trans-Pacific cruise around 40° N in August 1988. Those in the surface seawater varied widely with a mean of 162 ng S/1 and a standard deviation of 134 ng S/1 (n=37), but the variation was not a mere fluctuation and the high concentration (376 ng S/1) was found in the area between 145° W and 170° W. The atmospheric DMS concentration varied more widely with a mean value of 177 ng S/m³ and a standard deviation of 203 ng S/m³ (n=23). The diurnal variation of DMS was not significant in the air near the sea surface. However, the concentrations in the surface water was fairly well correlated with those in the surface air. The correlation coefficient (r ²=0.86) was larger than that between the atmospheric concentration and outflux of DMS (r ²=0.64). These findings mean that the turnover time of DMS in the atmosphere is not extremely short. Based on the linear relation between the atmospheric and seawater DMS, the turnover time of the atmospheric DMS has been calculated to be 0.9 days with an uncertainty of around 50%. The oxidation rate agrees fairly well with that expected from the OH radical concentration in the marine atmosphere.  相似文献   

Stock Structure Analysis of the Japanese Spanish Mackerel Scomberomorus niphonius (Cuvier, 1832) Along the China Coast Based on Truss Network     

Yiqian Jiang  Chi Zhang  Zhenjiang Ye  Binduo Xu  Yongjun Tian  Yoshiro Watanabe 《中国海洋大学学报(英文版)》2020,19(2):446-452

The Japanese Spanish mackerel Scomberomorus niphonius(Cuvier,1832)is widely distributed in the subtropical and temperate waters of the northwestern Pacific Ocean,supporting one of the most important commercial fisheries in China.However,ignoring the potential population structure changes induced by fishing pressure and climate change may undermine the population stability under the current management strategy.In this study,the population structure of the Japanese Spanish mackerel was investigated based on a morphometric truss network system.A total of 534 individuals were randomly collected from commercial gill nets spanning eight major spawning grounds in the Bohai,Yellow,and East China Seas during the peak spawning seasons respectively.A total of 17 measurements(including eye diameter)were conducted in each specimen and subjected to principal component analysis(PCA)and discriminant function analysis(DFA).The results of PCA indicated that the first two factors cumulatively caused 78.38%of the total morphometric variation and observable differences,primarily fin the caudal and trunk areas.The results of DFA revealed that the eight spawning groups can be divided into three stocks,i.e.,southern,middle,and northern stocks,with 68.7%of total accuracy.In contrast to previous studies,the spawning groups of the Japanese Spanish mackerel demonstrated a tendency to disperse to northern regions.In conclusion,this study found that to maintain the stability of the population structure and the total production of Japanese Spanish mackerel S.niphonius(Cuvier,1832),a newly revised management method should be developed and implemented.  相似文献   

Modelling of fractured carbonate reservoirs: outline of a novel technique via a case study from the Molasse Basin, southern Bavaria, Germany     

Mauro Cacace  Guido Blöcher  Norihiro Watanabe  Inga Moeck  Nele Börsing  Magdalena Scheck-Wenderoth  Olaf Kolditz  Ernst Huenges 《Environmental Earth Sciences》2013,70(8):3585-3602

Fluid flow in low-permeable carbonate rocks depends on the density of fractures, their interconnectivity and on the formation of fault damage zones. The present-day stress field influences the aperture hence the transmissivity of fractures whereas paleostress fields are responsible for the formation of faults and fractures. In low-permeable reservoir rocks, fault zones belong to the major targets. Before drilling, an estimate for reservoir productivity of wells drilled into the damage zone of faults is therefore required. Due to limitations in available data, a characterization of such reservoirs usually relies on the use of numerical techniques. The requirements of these mathematical models encompass a full integration of the actual fault geometry, comprising the dimension of the fault damage zone and of the fault core, and the individual population with properties of fault zones in the hanging and foot wall and the host rock. The paper presents both the technical approach to develop such a model and the property definition of heterogeneous fault zones and host rock with respect to the current stress field. The case study describes a deep geothermal reservoir in the western central Molasse Basin in southern Bavaria, Germany. Results from numerical simulations indicate that the well productivity can be enhanced along compressional fault zones if the interconnectivity of fractures is lateral caused by crossing synthetic and antithetic fractures. The model allows a deeper understanding of production tests and reservoir properties of faulted rocks.  相似文献   

Bulk parameterization for a vegetated surface and its application to a simulation of nocturnal drainage flow     

Tsutomu Watanabe 《Boundary-Layer Meteorology》1994,70(1-2):13-35

Two simple models are presented for describing the surface energy budget above vegetated surfaces. One is the traditional single-source model that includes only one energy budget equation for the entire canopy-soil system, and the other is the double-source model that includes separate energy budget equations for the vegetation canopy and the underlying soil surface. In both models, the bulk transfer coefficients needed to solve the energy budget equations are parameterized as functions of leaf area index, leaf transfer coefficients, and soil surface roughnesses to obtain the best fit to values calculated by a standard multilayer-canopy model. The validity of these models was tested by comparing their performance with that of the multilayer-canopy model for simulation of the surface energy balance and nocturnal drainage flow above vegetation. Results show that the double-source model gives reliable estimations for all cases ranging from sparse to dense vegetation covers; the single-source model is only applicable to dense, fully-covered vegetation. It is also shown that sparse vegetation weakens nocturnal drainage flow, since it isolates the cool underlying soil surface from the atmosphere above the canopy. This phenomenon cannot be described by a traditional single-source model incorporated commonly in many atmospheric models; however, the double-source model adequately describes this process.  相似文献