Effects of clear-cutting,meteorological, and physiological factors on evapotranspiration in the Kamabuchi experimental watershed in northern Japan     

Tayoko Kubota  Akira Kagawa  Toshio Abe  Ikuhiro Hosoda 《水文研究》2021,35(4):e14111

This study investigated the effects of clear-cutting and the meteorological and physiological factors on forest evapotranspiration (ET), by using the water-budget method in the Kamabuchi experimental watershed (KMB; 38° 56′ 21″ N, 140° 15′ 58″ E) in northern Japan. Meteorological and discharge data collected during no-snow periods (from June to October) from 1939 were used to compare ET in three sub-watersheds: No. 1, where the forest had been left undisturbed, and No. 2 and No. 3, where Cryptomeria japonica was planted after clear-cutting. Paired watershed experiments revealed that clear-cutting caused ET to decrease by approximately 100 mm yr⁻¹, and this reduction continued for more than 20 years, even after C. japonica was planted. ET fluctuated similarly across all watersheds, regardless of clear-cutting or planting. This fluctuation is mainly caused by solar radiation and temperature. Intrinsic water-use efficiency (iWUE) calculated using δ¹³C of tree-ring cellulose in C. japonica increased due to elevated atmospheric CO₂ concentration. We estimated annual carbon fixation in a single tree as the annual net photosynthesis (A). Subsequently, transpiration (E) was calculated from the relationship between iWUE and A. The results showed that A and E per tree increased as the tree grew older; however, the trees' responses to increasing c_a suppress the increase in ET. Moreover, the fluctuation of ET from the watershed was small compared to the fluctuation of P during the observation periods because the increase and decrease in E and interception loss complemented each other.  相似文献   

Estimating the nitrate concentration from the dissolved oxygen concentration and seawater temperature in the Kuroshio extension,Oyashio, and mixed water regions     

Miho Ishizu  Chiho Sukigara  Toshio Suga  Kelvin J. Richards 《Journal of Oceanography》2015,71(1):19-26

  相似文献   

Fast computation of Jacobian elliptic functions and incomplete elliptic integrals for constant values of elliptic parameter and elliptic characteristic     

Toshio Fukushima 《Celestial Mechanics and Dynamical Astronomy》2009,105(1-3):245-260

In order to accelerate the numerical evaluation of torque-free rotation of triaxial rigid bodies, we present a fast method to compute various kinds of elliptic functions for a series of the elliptic argument when the elliptic parameter and the elliptic characteristic are fixed. The functions we evaluate are the Jacobian elliptic functions and the incomplete elliptic integral of the second and third kinds regarded as a function of that of the first kind. The key technique is the utilization of the Maclaurin series expansion and the addition theorems with respect to the elliptic argument. The new method is around 25 times faster than the method using the incomplete elliptic integral of general kind and around 70 times faster than the method using mathematical libraries given in the latest version of Numerical Recipes.  相似文献   

An introduction to the South China Sea throughflow: Its dynamics, variability, and application for climate   总被引：9，自引：0，他引：9  

Tangdong Qu  Y. Tony Song  Toshio Yamagata 《Dynamics of Atmospheres and Oceans》2009,47(1-3):3

The South China Sea throughflow (SCSTF) involves the inflow through the Luzon strait and the outflow through the Karimata, Mindoro, and Taiwan straits. Recent studies have suggested that the SCSTF act as a heat and freshwater conveyor, playing a potentially important role in regulating the sea surface temperature pattern in the South China Sea and its adjoining tropical Indian and Pacific Oceans. In this introductory paper, we attempt to convey the progress that has recently been made in understanding the SCSTF. We first provide an overview of existing observations, theories, and simulations of the SCSTF. Then, we discuss its interaction with the Pacific western boundary current and Indonesian throughflow. Finally, we summarize issues and questions that remain to be addressed, with special reference to the SCSTF's dynamics, variability, and implication for climate.  相似文献   

Mineralogical and textural variation of silica minerals in hydrothermal flow-through experiments: Implications for quartz vein formation     

Atsushi Okamoto  Hanae Saishu  Nobuo Hirano  Noriyoshi Tsuchiya 《Geochimica et cosmochimica acta》2010,74(13):3692-3706

We conducted hydrothermal flow-through experiments at 430 °C and 31 MPa to investigate the mechanism of silica precipitation on granite under crustal conditions. Two experiments were performed using different input solutions: a single-component Si solution, and a multi-component solution with minor Al, Na, and K. The degree of supersaturation with respect to quartz, Ω = C_Si/C_Si,Qtz,eq, where C_Si and C_Si,Qtz,eq indicate Si concentration in solutions and the solubility of quartz within water, respectively, decreased from 3-3.5 to <1.1 along the flow path. A variety of silica minerals formed during the experiments (opal-A, opal-C, chalcedony, and quartz), and their occurrences and modal abundances changed in response to Ω and the presence of additives in the solution.For near-equilibrium solutions (Ω < ∼1.2), silica precipitation occurred in a simple way in both experiments, being restricted to overgrowths on pre-existing quartz surfaces in the granite. At higher saturation levels (Ω > ∼1.2), silica minerals were deposited on other surfaces in addition to quartz. In the single-component experiment, the dominant silica minerals changed in the order of opal-A → opal-C → quartz with decreasing Si concentration along the flow path. In contrast, in the multi-component experiment, quartz and minor chalcedony formed throughout the entire reaction vessel. This finding indicates that impurities (Na, K, and Al) in the solutions inhibited the precipitation of opal and enhanced the direct nucleation of quartz. The systematic appearance of metastable silica minerals were examined by nucleation processes and macroscopic precipitation kinetics. Our experimental results indicate that different precipitation mechanisms yield contrasting textures, which in turn suggests that vein textures can be used as indicators of solution chemistry within the fracture.  相似文献   

An earthquake swarm in the northern part of the Aso caldera and migration of their foci     

Akira Kubotera  Toshio Mitsunami   《Tectonophysics》1980,70(3-4):223-236

A seismicity gap was observed in the early stage of the activity of the earthquake swarm which has been taken place in the northern part of the Aso caldera during January 1975. In the following stage, small earthquakes began to occur, until at last the largest earthquake occured within the seismicity gap. The b-value appreciably increased after the largest earthquake. The above-mentioned characteristics of this earthquake swarm may be a typical example of the fracturing phenomena in relatively heterogeneous rocks. From the estimation of the ultimate strain energy that can be stored up in the seismicity gap, it may be concluded that the above-mentioned largest earthquake took place by the release of ultimate strain energy stored within the seismicity gap.  相似文献   

Transformation from Cartesian to Geodetic Coordinates Accelerated by Halley’s Method     

Toshio Fukushima 《Journal of Geodesy》2006,79(12):689-693

By using Halley’s third-order formula to find the root of a non-linear equation, we develop a new iterative procedure to solve an irrational form of the “latitude equation”, the equation to determine the geodetic latitude for given Cartesian coordinates. With a limit to one iteration, starting from zero height, and minimizing the number of divisions by means of the rational form representation of Halley’s formula, we obtain a new non-iterative method to transform Cartesian coordinates to geodetic ones. The new method is sufficiently precise in the sense that the maximum error of the latitude and the relative height is less than 6 micro-arcseconds for the range of height, −10 km ≤ h ≤ 30,000 km. The new method is around 50% faster than our previous method, roughly twice as fast as the well-known Bowring’s method, and much faster than the recently developed methods of Borkowski, Laskowski, Lin and Wang, Jones, Pollard, and Vermeille.  相似文献   

Molecular dynamics study of the crystal structure and phase relation of the GeO2 polymorphs     

Taku Tsuchiya  Takamitsu Yamanaka  Masanori Matsui 《Physics and Chemistry of Minerals》1998,25(2):94-100

A two-body interatomic potential model for GeO₂ polymorphs has been determined to simulate the structure change of them by semi-empirical procedure, total lattice energy minimization of GeO₂ polymorphs. Based on this potential, two polymorphs of GeO₂; α-quartz-type and rutile-type, have been reproduced using the molecular dynamics (MD) simulation techniques. Crystal structures, bulk moduli, volume thermal expansion coefficients and enthalpies of these polymorphs of GeO₂ were simulated. In spite of the simple form of the potential, these simulated structural values, bulk moduli and thermal expansivities are in excellent agreement with the reliable experimental data in respect to both polymorphs. Using this potential, MD simulation was further used to study the structural changes of GeO₂ under high pressure. We have investigated the pressure-induced amorphization. As reported in previous experimental studies, quartz-type GeO₂ undergoes pressure-induced crystalline-to-amorphous transformation at room temperature, the same as other quartz compounds; SiO₂, AlPO₄. Under hydrostatic compression, in this study, α-quartz-type GeO₂ transformed to a denser amorphous state at 7.4 GPa with change of the packing of oxygen ions and increase of germanium coordination. At higher pressure still, rutile-type GeO₂ transformed to a new phase of CaCl₂-type structure as a post-rutile candidate. Received: 29 July 1996 / Revised, accepted: 30 April 1997  相似文献   

TRMM/PR资料在中尺度模式MM5中的应用     

徐枝芳  葛文忠  党人庆  Toshio IGUCHI  Takao TAKADA 《大气科学进展》2003,20(2):185-193

将中尺度非静力模式MM5中的积云参数化Grell方案作了改进，使它含有降水云的云水，即雨水含量，并用该模式对1998年6月29日08时-30日08时(北京时)和1998年7月1日08时-2日08时(北京时)发生在淮河流域的两次特大暴雨进行数值模拟研究，同时通过采用R-qr关系将TRMM／PR(Tropical Rainfall Measuring Mission/Precipitation Radar)得到的降水强度资料月计算出比含水量qr，然后用qv′＝qv qr取代原模式中的比湿qv。结果表明将TRMM／PR资料加入模式后，由于PR雷达具有较高的空间分辨率，能够很好地反映中小尺度系统的空间结构，能够使湿度值接近实际，缩短了中尺度系统的发展时间，使得模拟出来的降雨强度、雨量中心位置以及雨带形状更接近实况。  相似文献   

青藏高原局地因素对近地表层地温的影响   总被引：23，自引：6，他引：23  

王绍令  丁永建  赵林  小池俊雄 《高原气象》2002,21(1):85-89

青藏高原近地表层地温既受区域性因素（高度、经度、纬度）控制，同时又受局地因素的影响。观测结果表明，高原稀疏植被地段比裸地地温高，短时期薄层雪盖起降低地温的作用，南坡比北坡地温高2－7℃，黑色沥青路面年平均温度比碎石土天然的年平均地表温度高4．5℃，亦高于其它材料的路面地温。  相似文献