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451.
Shigehisa Nakamura 《Marine Geodesy》2013,36(1):55-61
Specific properties of the interannual sea level variations and annual tides in the Northwestern Pacific were studied. Several tide stations were monitored. The monthly mean sea level for the year of 1995 was analyzed at each tide station. A seismic event in 1995, some tectonic activity around the subject area, and the Kuroshio (the oceanic western boundary current) may possibly contaminate results which would have occurred from the astronomical annual tide alone. 相似文献
452.
S. Nakamura 《Marine Geodesy》2013,36(2):195-209
The exceedance probability of tsunami occurrence in the eastern Pacific was estimated as an extended Poisson process. Estimation was also undertaken for several blocks in the eastern Pacific. Some tsunamis that originated off South America hit the Japanese islands after crossing the Pacific. 相似文献
453.
Federica Schiavi Katsura Kobayashi Takuya Moriguti Eizo Nakamura Massimo Pompilio Massimo Tiepolo Riccardo Vannucci 《Contributions to Mineralogy and Petrology》2010,159(4):541-561
During its 1800-year-long persistent activity the Stromboli volcano has erupted a highly porphyritic (HP) volatile-poor scoriaceous
magma and a low porphyritic (LP) volatile-rich pumiceous magma. The HP magma is erupted during normal Strombolian explosions
and lava effusions, while the LP one is related to more energetic paroxysms. During the March–April 2003 explosive activity,
Stromboli ejected two typologies of juvenile glassy ashes, namely highly vesicular LP shards and volatile-poor HP shards.
Their textural and in situ chemical characteristics are used to unravel mutual relationships between HP and LP magmas, as
well as magma dynamics within the shallow plumbing system. The mantle-normalized trace element patterns of both ash types
show the typical arc-lava pattern; however, HP glasses possess incompatible element concentrations higher than LP glasses,
along with Sr and Eu negative anomalies. HP shards are generally characterized by higher Li contents (to ~20 ppm) and lower
δ7Li values (+1.2 to −3.8‰) with respect to LP shards (Li contents of 7–14 ppm and δ7Li ranging between +4.6 and +0.9‰). Fractional crystallization models based on major and trace element compositions, combined
with a degassing model based on open-system Rayleigh distillation and on the assumption that melt/fluidDLi > 1, show that abundant (~30%) plagioclase precipitation and variable degrees of degassing can lead the more primitive LP
magma to evolve toward a differentiated (isotopically lighter) HP magma ponding in the upper conduit and undergoing slow continuous
degassing-induced crystallization. This study also evidences that in March 2003 Stromboli volcano poured out a small early
volume of LP magma that traveled slower within the conduit with respect to later and larger volumes of fast ascending LP magma
erupted during the April 5 paroxysm. The different ascent rates and cooling rates of the two LP magma batches (i.e., pre-
and post-paroxysm) resulted in small, but detectable, differences in their chemical signatures. Finally, this study highlights
the high potential of in situ investigations of juvenile glassy ashes in petrologic and geochemical monitoring the volcanic
activity and of Li isotopes as tracers of degassing processes within the shallow plumbing system. 相似文献
454.
The formation mechanism of the nocturnal urban boundary layer (UBL), especially in the winter nighttime, was investigated based on the extensive field observations conducted during November 1984 in Sapporo, Japan. A strong, elevated inversion formed over the Sapporo urban area and the inversion base height was approximately twice the average building height. Velocity fluctuations
u, w and Reynolds stress % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa0aaaeaaca% WG1bWaaWbaaSqabeaacaaIXaaaaGGaaOGae8hiaaIaam4DamaaCaaa% leqabaGaaGymaaaaaaaaaa!3A9C!\[\overline {u^1 w^1 } \] had nearly uniform profiles within the nocturnal UBL and decreased with height above the UBL. On the other hand, temperature fluctuations
t
, and heat fluxes % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa0aaaeaaca% WG1bWaaWbaaSqabeaacaaIXaaaaGGaaOGae8hiaaIaeqiUde3aaWba% aSqabeaacaaIXaaaaaaaaaa!3B56!\[\overline {u^1 \theta ^1 } \] and % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa0aaaeaaca% WG3bWaaWbaaSqabeaacaaIXaaaaGGaaOGae8hiaaIaeqiUde3aaWba% aSqabeaacaaIXaaaaaaaaaa!3B58!\[\overline {w^1 \theta ^1 } \] had peaks at the inversion base and small values within the nocturnal UBL. The turbulent kinetic energy budget showed that the turbulent transport term and shear generation from urban canopy elements are important in the nocturnal UBL development; the role of the buoyancy term is small. The turbulence data analysis and application of a simple advective model showed that the mechanism of UBL formation may be controlled by the downward transport of sensible heat from the elevated inversion caused by mechanically-generated turbulence.Nomenclature
g
accelaration due to gravity, m s-2
-
k
turbulent kinetic energy, m2 s-1
-
K
m
eddy viscosity, m2 s-1
-
L
Monin-Obukhov lenght, m
-
p
pressure, Kg m-2
-
U, V, W
mean wind speed in the downwind, crosswind, and vertical directions, respectively, m s-1
-
u
1, w
1
wind speed fluctuation in the downwind and vertical direction, respectively, m s-1
-
u
1
friction velocity, m s-1
- % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa0aaaeaaca% WG1bWaaWbaaSqabeaacaaIXaaaaGGaaOGae8hiaaIaam4DamaaCaaa% leqabaGaaGymaaaaaaaaaa!3A9C!\[\overline {u^1 w^1 } \]
momentum flux, m2s-2
- % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa0aaaeaaca% WG1bWaaWbaaSqabeaacaaIXaaaaGGaaOGae8hiaaIaam4DamaaCaaa% leqabaGaaGymaaaaaaaaaa!3A9C!\[\overline {u^1 \theta^1 } \]
sensible heat flux, m2s-1°C
-
WD
wind direction, deg
-
WS
wind speed, m s-1
-
z
altitude, m
-
Z
h
inversion base height, m
-
Z
j
wind maximum height, m
-
Z
t
inversion top height, m
-
T
u-r
heat island intensity, °C
-
temperature lapse rate at rural site, °C m-1
-
energy dissipation rate, m2s-3
-
1
Potential temperature fluctuation, °C
-
*
scaling temperature, (=-% MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa0aaaeaaca% WG1bWaaWbaaSqabeaacaaIXaaaaGGaaOGae8hiaaIaeqiUde3aaWba% aSqabeaacaaIXaaaaaaaaaa!3B56!\[\overline {u^1 \theta ^1 } \]/u*) °C
-
mean potential temperature fluctuation, K
-
density of air, Kgm-3
-
K
von Kármán constant (=0.4)
- u, v, w
standard deviation of wind speed in the downwind, crosswind, and vertical directions, respectively, m s-1
-
standard diviation of temperature, °C 相似文献
455.
Nobutaka Shimada Tomoki Nakamura Yasuo Morinaga Yoshihito Shikama 《Resource Geology》2005,55(2):91-100
Abstract. The presence of invisible gold was confirmed in arsenian pyrite from the Hishikari epithermal gold deposit, Kagoshima, Japan, by means of EPMA and SIMS analyses. The relative concentration of invisible gold may be positively correlated with As contents (0.01 to 10.37 wt%) of fine-grained arsenian pyrite which commonly occurs in the auriferous quartz veins. Although arsenian pyrite occurs widely in any mineralization stage with electrum and other sulfide, sulfosalts, selenide or telluride minerals, arsenian pyrites having higher As contents accompanied by invisible gold occur dominantly in the middle stage of fine-adularia-quartz and in the late stage of coarse-quartz rather than in the early stage of columnar-adularia. 相似文献
456.
Magma genesis beneath Northeast Japan arc: A new perspective on subduction zone magmatism 总被引:1,自引:2,他引:1
It is being accepted that earthquakes in subducting slab are caused by dehydration reactions of hydrous minerals. In the context of this “dehydration embrittlement” hypothesis, we propose a new model to explain key features of subduction zone magmatism on the basis of hydrous phase relations in peridotite and basaltic systems determined by thermodynamic calculations and seismic structures of Northeast Japan arc revealed by latest seismic studies. The model predicts that partial melting of basaltic crust in the subducting slab is an inevitable consequence of subduction of hydrated oceanic lithosphere. Aqueous fluids released from the subducting slab also cause partial melting widely in mantle wedge from just above the subducting slab to just below overlying crust at volcanic front. Hydrous minerals in the mantle wedge are stable only in shallow (< 120 km) areas, and are absent in the layer that is dragged into deep mantle by the subducting slab. The position of volcanic front is not restricted by dehydration reactions in the subducting slab but is controlled by dynamics of mantle wedge flow, which governs the thermal structure and partial melting regime in the mantle wedge. 相似文献
457.
P. L. Tikhomirov V. Yu. Prokof’ev I. A. Kal’ko A. V. Apletalin Yu. N. Nikolaev K. Kobayashi E. Nakamura 《Geotectonics》2017,51(2):131-151
The paper presents new data on the isotopic age and chemical composition of volcanic rocks from the Tytyl’veem and Mangazeika basins of western Chukotka superposed on Mesozoides of the Verkhoyansk–Chukotka Tectonic Region. The results of SIMS U–Pb zircon dating (121.4 ± 2.8 and 118.0 ± 2.0 Ma) corroborate the Aptian age of the Tytyl’veem Formation. This age, in turn, indicates its formation after closure of the South Anyui ocean (Neocomian), but before origination of the Okhotsk–Chukotka Belt (Albian–Campanian). Post-collisional Aptian igneous rocks are widespread in the northern Verkhoyansk–Chukotka Tectonic Region; the legth of the corresponding igneous province is no less than 1400 km. In geochemical characteristics, the post-collisional volcanic rocks occurring in Western Chukotka are similar with the rocks from Andean-type igneous belts. 相似文献
458.
Spatial variability and correlation of environmental proxies during the past 18,000 years among multiple cores from Lake Pumoyum Co,Tibet, China 总被引:3,自引:0,他引:3
Junbo Wang Liping Zhu Mitsugu Nishimura Toshio Nakamura Jianting Ju Manping Xie Watanabe Takahiro Matsunaka Testsuya 《Journal of Paleolimnology》2009,42(3):303-315
Multiple cores from Lake Pumoyum Co, southern Tibet, provide an improved understanding of the spatial distribution of lake
sediments, and how well they represent the paleo-climate. Comparative study of these cores using AMS 14C dating and environmental proxies clarified their relationships with environmental changes. Our work focused on understanding
the spatial similarities among cores covering different time scales, and evaluating variations in sedimentary processes across
sites. The four studied cores demonstrate different sedimentation rates, but environmental proxies help synchronize the timing
of environmental variations. Sediment variables such as total organic carbon (TOC), inorganic carbon (IC), and grain size
in different cores correlate well and corroborate changing trends over the past 10,000 cal years. Differences in sedimentation
rates and facies among core sites probably result largely from differences in water depth. The core from the deepest site
displays the highest average sedimentation rates and the highest accumulation rates of TOC, but lowest content of IC. Two
cores from somewhat shallower sites have plant residues in their lower sections and record similar variations in both the
number of layers and their depositional ages. Our results do not indicate any significant variation in sedimentation pattern
or its related factors among the three sites. A single core from the deepest site could adequately represent the total lake
environment over the time span covered. But cores from somewhat shallower sites might reveal important shifts in the environment
over a longer time period. 相似文献