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排序方式: 共有84条查询结果,搜索用时 15 毫秒
1.
Tomoki Oda Tomohiro Egusa Nobuhito Ohte Norifumi Hotta Nobuaki Tanaka Mark B. Green Masakazu Suzuki 《水文研究》2021,35(5):e14177
Understanding changes in evapotranspiration during forest regrowth is essential to predict changes of stream runoff and recovery after forest cutting. Canopy interception (Ic) is an important component of evapotranspiration, however Ic changes and the impact on stream runoff during regrowth after cutting remains unclear due to limited observations. The objective of this study was to examine the effects of Ic changes on long-term stream runoff in a regrowth Japanese cedar and Japanese cypress forest following clear-cutting. This study was conducted in two 1-ha paired headwater catchments at Fukuroyamasawa Experimental Watershed in Japan. The catchments were 100% covered by Japanese coniferous plantation forest, one of which was 100% clear-cut in 1999 when the forest was 70 years old. In the treated catchment, annual runoff increased by 301 mm/year (14% of precipitation) the year following clear-cutting, and remained 185 mm/year (7.9% of precipitation) higher in the young regrowth forest for 12–14 years compared to the estimated runoff assuming no clear-cutting. The Ic change was −358 mm/year (17% of precipitation) after cutting and was −168 mm/year (6.7% of precipitation) in the 12–14 years old regrowth forest compared to the observed Ic during the pre-cutting period. Stream runoff increased in all seasons, and the Ic change was the main fraction of evapotranspiration change in all seasons throughout the observation period. These results suggest that the change in Ic accounted for most of the runoff response following forest cutting and the subsequent runoff recovery in this coniferous forest. 相似文献
2.
Yoshio Kubo 《Celestial Mechanics and Dynamical Astronomy》1990,50(2):165-187
Hamiltonian mechanics is applied to the problem of the rotation of the elastic Earth. We first show the process for the formulation of the Hamiltonian for rotation of a deformable body and the derivation of the equations of motion from it. Then, based on a simple model of deformation, the solution is given for the period of Euler motion, UT1 and the nutation of the elastic Earth. In particular it is shown that the elasticity of the Earth acts on the nutation so as to decrease the Oppolzer terms of the nutation of the rigid Earth by about 30 per cent. The solution is in good agreement with results which have been obtained by other, different approaches. 相似文献
3.
Diel patterns in the chlorophyll a specific absorption coefficient of surface picoplankton, a*pico (γ) (m2·[mg chlorophyll a]−1), were studied at 7 stations under daily cycle of in situ light condition in the western subarctic Pacific and Japan Sea. All the data were normalized by dividing the anomaly with daily averaged a*pico (γ). Opposite diel patterns were observed for the normalized a*pico (443) and a*pico (675) with maximum toward dawn or dusk and minimum toward midday at 4 stations under low-irradiance (LI) conditions and vice versa at 3 stations under high-irradiance (HI) conditions. The absorption efficiency factors at red absorption peak, Q
a (675), were determined by reconstruction with intracellular chlorophyll a concentration and cell diameter. The normalized Q
a (675) also showed diel pattern with maximum toward midday and minimum toward dawn or dusk under LI. The diel pattern in a*pico (675) and Q
a (675) were primarily caused by changes in intracellular chlorophyll a concentration due to photoadaptation under LI. The diel pattern in a*pico (443) was influenced by pigmentation, as recognized by blue to red ratio [a*pico (443)/a*pico (675)] under HI. This study proposed that the opposite diel pattern in a*pico (γ) might occur for a wide range of algal species. The results presented here have important consequences for the interpretation of diel variations in optical properties observed in the open ocean. 相似文献
4.
Yukio Agatsuma Nobuyasu Nakabayashi Nobuaki Miura & Kazuya Taniguchi 《Marine Ecology》2005,26(2):100-109
To clarify the differences in the growth and gonad size of the sea urchin Hemicentrotus pulcherrimus among algal sere, the study was conducted in June and July, and September 1998 at three fucoid beds in Oga and at three algal turfs in Hachimori, Akita Prefecture in northern Japan. The most rapid growth was observed in a large perennial fucoid bed at the climax stage. Growth in a small perennial Chondrus ocellatus‐dominated bed in algal turfs in the seral stage was then high. The slowest growth was observed in the small perennial Dictyopteris divaricata‐ and Laurencia spp.‐dominated beds which are known to possess chemicals which act as feeding deterrents against the sea urchins. The gonad index (gonad wet weight × 100/body wet weight) at a fucoid bed was high where standing crops exceeded 3 kg·m?2. The gonad index in the Laurencia bed was lower than those at fucoid beds. These results suggest that growth and gonad production are affected by algal sere and differ among species of small perennial algae in the seral stage with or without chemical defense. 相似文献
5.
C. E. Runge A. Kubo B. Kiefer Y. Meng V. B. Prakapenka G. Shen R. J. Cava T. S. Duffy 《Physics and Chemistry of Minerals》2006,33(10):699-709
The equation of state of MgGeO3 perovskite was determined between 25 and 66 GPa using synchrotron X-ray diffraction with the laser-heated diamond anvil cell. The data were fit to a third-order Birch–Murnaghan equation of state and yielded a zero-pressure volume (V 0) of 182.2 ± 0.3 Å3 and bulk modulus (K 0) of 229 ± 3 GPa, with the pressure derivative (K′0 = (?K 0/?P) T ) fixed at 3.7. Differential stresses were evaluated using lattice strain theory and found to be typically less than about 1.5 GPa. Theoretical calculations were also carried out using density functional theory from 0 to 205 GPa. The equation of state parameters from theory (V 0 = 180.2 Å3, K 0 = 221.3 GPa, and K′0 = 3.90) are in agreement with experiment, although theoretically calculated volumes are systematically lower than experiment. The properties of the perovskite phase were compared to MgGeO3 post-perovskite phase near the observed phase transition pressure (~65 GPa). Across the transition, the density increased by 2.0(0.7)%. This is in excellent agreement with the theoretically determined density change of 1.9%; however both values are larger than those for the (Mg,Fe)SiO3 phase transition. The bulk sound velocity change across the transition is small and is likely to be negative [?0.5(1.6)% from experiment and ?1.2% from theory]. These results are similar to previous findings for the (Mg,Fe)SiO3 system. A linearized Birch–Murnaghan equation of state fit to each axis yielded zero-pressure compressibilities of 0.0022, 0.0009, and 0.0016 GPa?1 for the a, b, and c axis, respectively. Magnesium germanate appears to be a good analog system for studying the properties of the perovskite and post-perovskite phases in silicates. 相似文献
6.
Abstract Magnetic measurements were carried out to investigate rock magnetic properties and paleomagnetic directions of late and middle Miocene sediments recovered from the land side of the Japan Trench during the Ocean Drilling Program Leg 186. Because the low coercive component in natural remanent magnetization (NRM) normalized by anhysteretic remanent magnetization shows that the drilling‐induced magnetization is severe in the sections obtained by the advanced hydraulic piston coring method, careful analyses of demagnetization of NRM using the ‘demagnetization plane’ were carried out to decompose the direction and intensity. Magnetostratigraphic correlation down to the upper Miocene, supplemented by biostratigraphic data, revealed that the sedimentation rates are characterized by drastic changes, with the early Pliocene having the highest rate. This high sedimentation rate is related to the subsidence of the southern deep‐sea terrace of the Japan Trench. 相似文献
7.
Yoshio Kubo 《Celestial Mechanics and Dynamical Astronomy》2011,110(2):143-168
Under perturbations from outer bodies, the Earth experiences changes of its angular momentum axis, figure axis and rotational
axis. In the theory of the rigid Earth, in addition to the precession and nutation of the angular momentum axis given by the
Poisson terms, both the figure axis and the rotational axis suffer forced deviation from the angular momentum axis. This deviation
is expressed by the so-called Oppolzer terms describing separation of the averaged figure axis, called CIP (Celestial Intermediate
Pole) or CEP (Celestial Ephemeris Pole), and the mathematically defined rotational axis, from the angular momentum axis. The
CIP is the rotational axis in a frame subject to both precession and nutation, while the mathematical rotational axis is that
in the inertial (non-rotating) frame. We investigate, kinematically, the origin of the separation between these two axes—both
for the rigid Earth and an elastic Earth. In the case of an elastic Earth perturbed by the same outer bodies, there appear
further deviations of the figure and rotational axes from the angular momentum axis. These deviations, though similar to the
Oppolzer terms in the rigid Earth, are produced by quite a different physical mechanism. Analysing this mechanism, we derive
an expression for the Oppolzer-like terms in an elastic Earth. From this expression we demonstrate that, under a certain approximation
(in neglect of the motion of the perturbing outer bodies), the sum of the direct and convective perturbations of the spin
axis coincides with the direct perturbation of the figure axis. This equality, which is approximate, gets violated when the
motion of the outer bodies is taken into account. 相似文献
8.
J. M. Borrero S. Tomczyk M. Kubo H. Socas-Navarro J. Schou S. Couvidat R. Bogart 《Solar physics》2011,273(1):267-293
In this paper we describe in detail the implementation and main properties of a new inversion code for the polarized radiative
transfer equation (VFISV: Very Fast Inversion of the Stokes Vector). VFISV will routinely analyze pipeline data from the Helioseismic
and Magnetic Imager (HMI) on-board of the Solar Dynamics Observatory (SDO). It will provide full-disk maps (4096×4096 pixels)
of the magnetic field vector on the Solar Photosphere every ten minutes. For this reason VFISV is optimized to achieve an
inversion speed that will allow it to invert sixteen million pixels every ten minutes with a modest number (approx. 50) of
CPUs. Here we focus on describing a number of important details, simplifications and tweaks that have allowed us to significantly
speed up the inversion process. We also give details on tests performed with data from the spectropolarimeter on-board of
the Hinode spacecraft. 相似文献
9.
Marilyn B. Vogel David J. Des Marais Mary N. Parenteau Linda L. Jahnke Kendra A. Turk Michael D.Y. Kubo 《Sedimentary Geology》2010,223(3-4):265-280
Gypsum (CaSO4·2H2O) deposits from a range of sedimentary environments at Guerrero Negro, Baja California Sur, Mexico were investigated for microscale texture and composition in order to differentiate features formed under substantial microbial influence from those for which microbial effects were relatively minor or absent. Gypsum deposits were classified according to their sedimentary environment, textures, crystal habit, brine composition and other geochemical factors. The environments studied included subaqueous sediments in anchialine pools and in solar salterns, as well as subsurface sediments of mudflats and saltpans. Gypsum that developed in the apparent absence of biofilms included crystals precipitated in the water column and subsedimentary discs that precipitated from phreatic brines. Subsedimentary gypsum developed in sabkha environments exhibited a sinuous microtexture and poikilitically enclosed detrital particles. Water column precipitates had euhedral prismatic habits and extensive penetrative twinning. Gypsum deposits influenced by biofilms included bottom nucleated crusts and gypsolites developing in anchialine pools and saltern ponds. Gypsum precipitating within benthic biofilms, and in biofilms within subaerial sediment surfaces provided compelling evidence of biological influences on crystal textures and habits. This evidence included irregular, high relief surface textures, accessory minerals (S°, Ca-carbonate, Sr/Ca-sulfate and Mg-hydroxide) and distinctive crystal habits such as equant forms and crystals having distorted prism faces. 相似文献
10.
Yoshio Kubo 《Celestial Mechanics and Dynamical Astronomy》1979,19(3):215-241
Effects of an interaction between the mantle and the core of the Earth on its rotational motion are investigated. Assuming that the Earth consists of a rigid mantle and a rigid core with a frictional coupling and a kind of inertial coupling between them, the equations of motion are derived, and they are solved in a close approximation. The solution gives the expressions for the precession, the nutation, the secular changes in the obliquity and the rotational speed, the polar motion and so on as functions of the magnitudes of these forces. A numerical estimation shows that the effect of the friction on the amplitude and phase of the nutation is small for a reasonable intensity of the friction while inertial coupling force has a decisive influence on the amplitude, and an appropriately chosen value of the latter force gives a nutation which closely agrees with observations. It is also indicated that this torque remarkably lessens the rates of the secular changes in the obliquity and the rotational speed. The possibility of a periodical change in the amplitude of the polar motion is suggested as a result of the interaction between the two consituents. 相似文献