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101.
Shin-ichi Takehiro Masaki Ishiwatari Kensuke Nakajima Yoshi-Yuki Hayashi 《地球物理与天体物理流体动力学》2013,107(6):439-459
Linear stability of rotating thermal convection in a horizontal layer of Boussinesq fluid under the fixed heat flux boundary condition is examined by the use of a vertically truncated system up to wavenumber one. When the rotation axis is in the vertical direction, the asymptotic behavior of the critical convection for large rotation rates is almost the same as that under the fixed temperature boundary condition. However, when the rotation axis is horizontal and the lateral boundaries are inclined, the mode with zero horizontal wavenumber remains as the critical mode regardless of the rotation rate. The neutral curve has another local minimum at a nonzero horizontal wavenumber, whose asymptotic behavior coincides with the critical mode under the fixed temperature condition. The difference of the critical horizontal wavenumber between those two geometries is qualitatively understood by the difference of wave characteristics; inertial waves and Rossby waves, respectively. 相似文献
102.
Water level monitoring provides essential information about the condition of aquifers and their responses to water extraction, land‐use change, and climatic variability. It is important to have a spatially distributed, long‐term monitoring well network for sustainable groundwater resource management. Community‐based monitoring involving citizen scientists provides an approach to complement existing government‐run monitoring programs. This article demonstrates the feasibility of establishing a large‐scale water level monitoring network of private water supply wells using an example from Rocky View County (3900 km2) in Alberta, Canada. In this network, community volunteers measure the water level in their wells, and enter these data through a web‐based data portal, which allows the public to view and download these data. The close collaboration among the university researchers, county staff members, and community volunteers enabled the successful implementation and operation of the network for a 5‐year pilot period, which generated valuable data sets. The monitoring program was accompanied by education and outreach programs, in which the educational materials on groundwater were developed in collaboration with science teachers from local schools. The methodology used in this study can be easily adopted by other municipalities and watershed stewardship groups interested in groundwater monitoring. As governments are starting to rely increasingly on local municipalities and conservation authorities for watershed management and planning, community‐based groundwater monitoring provides an effective and affordable tool for sustainable water resources management. 相似文献
103.
Masahiro Sakata Masaki Yamada Satoshi Mitsunobu Yasuhiro Senga 《Journal of Oceanography》2012,68(5):807-813
The contribution of abiogenic and biogenic particles to trace-metal (As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sb, Ti, V, and Zn) composition was investigated for phytoplankton (primarily diatoms) collected in Shimizu Port, a coastal seawater region. Except for Cd, the trace metals occurred predominantly in lithogenic or nonlithogenic abiogenic particles associated with plankton. In contrast, it is likely that Cd in seawater is taken up intracellularly, and not adsorbed extracellularly by phytoplankton. The lower P-normalized quotas of Cd in Shimizu Port than in offshore regions may be because plankton are dominated by diatoms. 相似文献
104.
Yoshimitsu Masaki Tsuneo Kuwagata Yasushi Ishigooka 《Theoretical and Applied Climatology》2010,100(3-4):283-297
We have developed a method for estimating hourly global solar radiation (GSR) from hourly sunshine duration data. This procedure requires only hourly sunshine duration as the input data and utilizes hourly precipitation and daily snow cover as auxiliary data to classify time intervals into six cases according to weather conditions. To obtain hourly GSR using a simple algebraic form, a quadratic function of the solar elevation angle and the sunshine duration ratio is used. Daily GSR is given by a sum of hourly GSRs. We evaluated the performance of the newly developed method using data obtained at 67 meteorological stations and found that the estimated GSR is highly consistent with that observed. Hourly and daily root-mean-square misfits are approximately 0.2 MJ/m2/h (~55 W/m2) and 1.4 to 1.5 MJ/m2/day (~16 to 17 W/m2), respectively. Our classification of weather conditions is effective for reducing estimation errors, especially under cloudy skies. Since the sunshine duration is observed at more meteorological stations than GSR, the proposed new method is a powerful tool for obtaining solar radiation with hourly resolution and a dense geographical distribution. One of the proposed methods, GSRgrn, can be applicable to hourly GSR estimations at different observation sites by setting local parameters (the precipitable water, surface albedo, and atmospheric turbidity) suitable to the sites. The hourly GSR can be applied for various micrometeorological studies, such as the heat budget of crop fields. 相似文献
105.
Keigo Yamamoto Hirotaka Tsujimura Masaki Nakajima Paul J. Harrison 《Journal of Oceanography》2013,69(6):727-736
The first observation of a red tide of the toxic dinoflagellate Alexandrium tamarense in the Yodo River estuary, Osaka Bay, Japan was in the spring of 2007. To clarify which environmental factors controlled the abundance of A. tamarense, field surveys were conducted in 2008 and 2009. In 2008, the increase of A. tamarense occurred from early to mid-March and temperatures ranged from 9 to 13 °C. In contrast, in 2009, the increase was 1 month later, from early to mid-April and therefore temperatures were higher. In both years, A. tamarense was most abundant when salinities were relatively high (15–25), river discharge was low, and the water column was stable. There were no cells during periods of low salinity (<10), high discharge. In 2008, possibly silicate and phosphate were limiting during the simultaneous diatom and A. tamarense bloom in early March with silicate restricting the further growth of diatoms. In this estuarine basin, freshwater discharge from the weir increased the flow rate at stations downstream of the weir and deterred bloom formation by A. tamarense. Conversely, the lack of discharge increased the salinity and stability of the water column and decreased in the flow rate in the river/estuary. This process promoted the initiation of the bloom of A. tamarense and the subsequent accumulation of paralytic shellfish toxin in the brackish water clam Corbicula japonica. It is recommended that a constant discharge from the weir is maintained in order to prevent blooms of A. tamarense and subsequent paralytic shellfish poisoning (PSP) incidents in this area. 相似文献
106.
Calorimetric measurements of fusion enthalpies for Ni2SiO4 and Co2SiO4 olivines were carried out using a high-temperature calorimeter, and Ni and Co partitioning between olivine and silicate liquid was analyzed using the measured heats of fusion. The fusion enthalpy of Co2SiO4 olivine measured by transposed-temperature drop calorimetry was 103 ± 15 kJ/mol at melting point (1688 K). The fusion enthalpy of Ni2SiO4 olivine was calculated based on the enthalpies of liquids in the system An50Di50-Ni2SiO4 measured by transposed-temperature drop calorimetry at 1773 K, and was 221 ± 26 kJ/mol at its metastable melting point (1923 K). The fusion enthalpy of Ni2SiO4 is the largest among those of olivine group, this is caused by the large crystal field stabilization energy of six-coordinated Ni2+ in olivine. The larger fusion enthalpy of Ni2SiO4 can account for the large and variable partition coefficient of Ni between olivine and silicate liquid. Based on the comparison between partition coefficients calculated from thermodynamic data and those observed in partition experiments, it is considered that the magnitude of partition coefficients is primarily dependent on the heats of fusion of the components. Furthermore, the activity coefficients for Ni-, Co- and Mn-bearing components in magmatic liquid are nearly of the same magnitude. 相似文献
107.
Masaki Morimoto 《Astrophysics and Space Science》1986,118(1-2):63-65
The title telescope — in operation since 1982 — gives a surface accuracy of better than 0.2 mm (r.m.s.), with an aperture efficiency of about 25% at 115 GHz. A 5-element interferometer is at final adjustment stage. Observations of proto-stellar objects, extragalactic objects, and spectral lines are briefly described.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984. 相似文献
108.
109.
Ground water exchange affects the ecology of surface water by sustaining stream base flow and moderating water-level fluctuations of ground water-fed lakes. It also provides stable-temperature habitats and supplies nutrients and inorganic ions. Ground water input of nutrients can even determine the trophic status of lakes and the distribution of macrophytes. In streams the mixing of ground water and surface water in shallow channel and bankside sediments creates a unique environment called the hyporheic zone, an important component of the lotic ecosystem. Localized areas of high ground water discharge in streams provide thermal refugia for fish. Ground water also provides moisture to riparian vegetation, which in turn supplies organic matter to streams and enhances bank resistance to erosion. As hydrologists and ecologists interact to understand the impact of ground water on aquatic ecology, a new research field called "ecohydrology" is emerging. 相似文献
110.