Applying the adjoint-free 4dVar assimilation to modeling the Kuroshio south of Japan     

Miyazawa  Yasumasa  Yaremchuk  Max  Varlamov  Sergey M.  Miyama  Toru  Aoki  Kunihiro 《Ocean Dynamics》2020,70(8):1129-1149

Ocean Dynamics - Operational ocean nowcast/forecast systems require real-time sampling of oceanic data for representing realistic oceanic conditions. Satellite altimetry plays a key role in...  相似文献   

Spatial distribution and temporal trends of rainfall and erosivity in the Eastern Africa region   总被引：1，自引：0，他引：1       下载免费PDF全文

Ayele Almaw Fenta  Hiroshi Yasuda  Katsuyuki Shimizu  Nigussie Haregeweyn  Takayuki Kawai  Dagnenet Sultan  Kindiye Ebabu  Ashebir Sewale Belay 《水文研究》2017,31(25):4555-4567

Soil erosion by water is one of the main environmental concerns in the drought‐prone Eastern Africa region. Understanding factors such as rainfall and erosivity is therefore of utmost importance for soil erosion risk assessment and soil and water conservation planning. In this study, we evaluated the spatial distribution and temporal trends of rainfall and erosivity for the Eastern Africa region during the period 1981–2016. The precipitation concentration index, seasonality index, and modified Fournier index have been analysed using 5 × 5‐km resolution multisource rainfall product (Climate Hazards Group InfraRed Precipitation with Stations). The mean annual rainfall of the region was 810 mm ranging from less than 300 mm in the lowland areas to over 1,200 mm in the highlands being influenced by orography of the Eastern Africa region. The precipitation concentration index and seasonality index revealed a spatial pattern of rainfall seasonality dependent on latitude, with a more pronounced seasonality as we go far from the equator. The modified Fournier index showed high spatial variability with about 55% of the region subject to high to very high rainfall erosivity. The mean annual R‐factor in the study region was calculated at 3,246 ± 1,895 MJ mm ha^?1 h^?1 yr^?1, implying a potentially high water erosion risk in the region. Moreover, both increasing and decreasing trends of annual rainfall and erosivity were observed but spatial variability of these trends was high. This study offers useful information for better soil erosion prediction as well as can support policy development to achieve sustainable regional environmental planning and management of soil and water resources.  相似文献   

Public acceptance of the oceanic carbon sequestration     

Norihiro Kamishiro  Toru Sato 《Marine Policy》2009

CO₂ ocean sequestration may be an effective option for mitigating global warming. There are risks associated with this process, particularly the local impact on deep-sea environments. Public acceptance is required for the implementation of this technology, even though the impacts have been proven to be trivial. In this study, a questionnaire survey was conducted to find the correlation between public acceptance of CO₂ sequestration and influential factors by covariance structure analysis. In addition, risk communication via the Internet was carried out. These analyses revealed that careful investigation of the target oceanic site and field experiments are important in gaining public acceptance of CO₂ sequestration.  相似文献   

Erratum to “Environmental control of short-term variation in the plankton community of inner Tokyo Bay, Japan” [Estuar., Coast. Shelf Sci. 78 (2008) 796–810]     

Toru Nakane  Kisaburo Nakata  Heather Bouman  Trevor Platt 《Estuarine, Coastal and Shelf Science》2008,80(4):598

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Evaluation of the non-hydrostatic stress produced in a multi-anvil high pressure apparatus     

Jun-ichi Ando  Tetsuo Irifune  Toru Takeshita  Kiyoshi Fujino 《Physics and Chemistry of Minerals》1997,24(2):139-148

Olivine single crystals have been deformed under high confining pressure (P=5?GPa) and temperature (T=1400?°C) conditions in a multi-anvil high pressure apparatus. NaCl, diamond and NaCl+diamond (2:1 by volume) powders were encapsulated along with the olivine single crystals in order to produce a range of stress states. The change of the non-hydrostatic stress transmitted to the olivine samples, enclosed within these three different media, during heating has been evaluated by observation of dislocation microstructure and density. A higher differential stress can be generated with diamond powder (0.1?GPa) than with NaCl powder (0.02?GPa). Although an intermediate differential stress between 0.1?GPa and 0.02?GPa had been expected to be generated using NaCl+diamond powder, the generation of non-hydrostatic stress in the olivine sample was unsuccessful. This may be caused by the fact that compaction (or sintering) proceeded in the capsule throughout the experiments. The most important finding of these experiments is that a constant non-hydrostatic stress can be applied to a sample under very high pressure and temperature conditions within the multi-anvil high pressure apparatus for the duration of the experiment. This approach is therefore suitable for investigating the steady-state rheological properties of mantle minerals at near-mantle conditions.  相似文献   

The build-up of the colour–magnitude relation as a function of environment     

Masayuki Tanaka  Tadayuki Kodama  Nobuo Arimoto  Sadanori Okamura  Keiichi Umetsu  Kazuhiro Shimasaku  Ichi Tanaka  Toru Yamada 《Monthly notices of the Royal Astronomical Society》2005,362(1):268-288

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Field Survey of Tsunami Effects in Sri Lanka due to the Sumatra-Andaman Earthquake of December 26, 2004     

Shusaku Inoue  Anil C. Wijeyewickrema  Hiroyuki Matsumoto  Hiroyuki Miura  Priyantha Gunaratna  Manoj Madurapperuma  Toru Sekiguchi 《Pure and Applied Geophysics》2007,164(2-3):395-411

The December 26, 2004 Sumatra-Andaman earthquake that registered a moment magnitude (M_w) of 9.1 was one of the largest earthquakes in the world since 1900. The devastating tsunami that resulted from this earthquake caused more casualties than any previously reported tsunami. The number of fatalities and missing persons in the most seriously affected countries were Indonesia - 167,736, Sri Lanka - 35,322, India - 18,045 and Thailand - 8,212. This paper describes two field visits to assess tsunami effects in Sri Lanka by a combined team of Japanese and Sri Lankan researchers. The first field visit from December 30, 2004 – January 04, 2005 covered the western and southern coasts of Sri Lanka including the cities of Moratuwa, Beruwala, Bentota, Pereliya, Hikkaduwa, Galle, Talpe, Matara, Tangalla and Hambantota. The objectives of the first field visit were to investigate the damage caused by the tsunami and to obtain eyewitness information about wave arrival times. The second field visit from March 10–18, 2005 covered the eastern and southern coasts of Sri Lanka and included Trincomalee, Batticaloa, Arugam Bay, Yala National Park and Kirinda. The objectives of the second visit were mainly to obtain eyewitness information about wave arrival times and inundation data, and to take relevant measurements using GPS instruments.  相似文献   

A Simple Theoretical Radiation Scheme for Regular Building Arrays     

Manabu?KandaEmail author  Toru?Kawai  Kiyotaka?Nakagawa 《Boundary-Layer Meteorology》2005,114(1):71-90

We propose a simple theoretical radiation scheme for regular building arrays. The essential difference of the present radiation scheme from the previous ones is the explicit consideration of the three-dimensional features of the surface geometry. The model is assumed to be an infinitely extended regular array of uniform buildings, each building composed of six faces (roof, floor, and four vertical walls). Without using time-consuming iterations or statistical approaches, we calculated the view factors of the faces, the complicated sunlit--shadow distributions, and the resulting canopy albedo for any time and location. The model was evaluated by comparing to outdoor experiments in a wide range of seasons and surface geometries. The simulated canopy albedos agreed well with measured values, and the accuracy is a significant improvement over two-dimensional-based model outputs.  相似文献   

The role of pore water in the mechanical behavior of unsaturated soils     

Daizo Karube  Katsuyuki Kawai 《Geotechnical and Geological Engineering》2001,19(3-4):211-241

Deformation and failure of soils are governed by the stresses acting on the soil skeleton. The isotropic stress acting on the soil skeleton can be divided into two components. One is the stress component which is transmitted through the soil skeleton. This skeleton stress is influenced by the pore water (bulk water) in the soil. The other is the internal stress component which does not contribute to equilibrium with a given external force. The internal stress is induced by the capillary tension of meniscus water clinging to the contact point of soil particles and acts so as to connect the soil particles tightly. Therefore, in modeling the stress and strain relations for unsaturated soils, it is of much importance to quantitatively evaluate how the pore water exists in the soil. This paper discusses the role of pore water on the mechanical behaviour of the soil. In particular, the significance of the water retention curve is emphasized from a mechanical viewpoint. Essential features required in modeling of the constitutive relations for unsaturated soils are discussed and presented.  相似文献   

Bio-Optical Relationship of Case I Waters: The Difference between the Low- and Mid-Latitude Waters and the Southern Ocean     

Toru Hirawake  Hiroo Satoh  Takashi Ishimaru  Yukuya Yamaguchi  Motoaki Kishino 《Journal of Oceanography》2000,56(3):245-260

Both historic and currently operational chlorophyll algorithms of the satellite-borne ocean color sensors, such as SeaWiFS, were evaluated for in situ spectral radiation and chlorophyll data in some Case I waters, including the waters in the Indian Ocean sector of the Southern Ocean. Chlorophyll a concentration of the data set (n = 73) ranged from 0.04 to 1.01 mg m^–3. The algorithms had higher accuracy for the low- and mid-latitude waters (RMSE: 0.163–0.253), specifically the most recently developed algorithms of OCTS and Sea WiFS showed 0.163 and 0.170 of Root Mean Square Errors, respectively. However, these algorithms had large errors (0.422–0.621) for the Southern Ocean data set and underestimated the surface chlorophyll by more than a factor of 2.6. The absorption coefficients in the blue spectral region retrieved from remote sensing reflectance varied in a nonlinear manner with chlorophyll a concentration, and the value in the Southern Ocean was significantly lower than that in the low- and mid-latitude waters for each chlorophyll a concentration. The underestimation of chlorophyll a concentration in the Southern Ocean with these algorithms was caused by the lower specific absorption coefficient in the region compared with the low- and mid-latitude waters under the same chlorophyll a concentration.  相似文献