Heat and salt balances in the Seto Inland Sea   总被引：1，自引：0，他引：1  

Mayumi Murakami  Yukio Oonishi  Hideaki Kunishi 《Journal of Oceanography》1989,45(3):204-216

Seasonal variations of heat and salt balances are estimated in the Seto Inland Sea with the use of a numerical experiment.The surface effect is dominant with respect to the heat balance. In spring, however, the effect of the horizontal heat transport is the same as or greater than that of the surface heating (or cooling). Annual mean heat transport is 85 cal cm^–2 day^–1 (356 J cm^–2 day^–1) which is supplied from the open ocean and lost through the sea surface in the Inland Sea as a whole. Because of the shallow water depth, heat is supplied through the surface and carried out by the horizontal heat transport in Hiuchi- and Bingo-nada in the annual mean. The heat transport has the opposite sense to that in the whole Seto Inland Sea and annual mean transport is negative (–10 cal cm^–2 day^–1,i.e., –42 J cm^–2 day^–1).The salt balance is primarily controlled by the river discharge and the surface effect (precipitation) in June and July. In the other months, the effects of horizontal salt transport, of river inflow and of sea surface exchange (especially of the evaporation in autumn) are comparable to each other. In the Bungo Channel the river effect is relatively small. Osaka Bay and the Kii Channel are characterized by a smaller surface effect.Contribution No. 446 from Tohoku Regional Fisheries Research Laboratory.  相似文献   

Probability of earthquake occurrence as obtained from a Weibull distribution analysis of crustal strain   总被引：2，自引：0，他引：2  

Yukio Hagiwara 《Tectonophysics》1974,23(3):313-318

Probability of a large-scale earthquake occurrence is estimated from crustal strain geodetically detected over an earthquake area. The Weibull distribution function, which is widely applied to quality-control research, is made use of in this paper in the probabilistic treatments of crustal strain.Using the table of ultimate strain presented by Rikitake (1974), a Weibull model representing a statistical distribution of crustal-rupture occurrence time is determined on the assumption that the crust is strained with a constant speed. In the case of the South Kanto District, the associated probability-density function has a maximum at about 84 years after the time when the strain energy accumulation starts.  相似文献   

A widespread simultaneous increase of the microearthquake seismicity and minor crustal movements in and around the assumed rupture zone of the Tokai earthquake     

Yukio Fujinawa 《Natural Hazards》1988,1(3):255-276

Data from an extensive routine network and a high-density temporary seismic observation using the ocean bottom seismometer in and around Suruga Bay, Japan, showed that a simultaneous increase of microearthquake seismicity occurred from mid-July 1984 (Ukawa et al., 1988). The area extended over a region of about 60 km (NS) × 80 km (EW), and is nearly included in the assumed fault zone of the presumed Tokai earthquake. The analyses of the bore-hole ground tilt and volumetric strain data revealed that an anomalous small ground tilt and volumetric strain change occurred at the time of the seismic activity with a duration of about a month. Data of geodetic measurements, groundwater, and radon content were examined with the result that many observational items showed small anomalies during that period. The observed crustal movement was compared with that of slip models of the Philippine Sea plate around Suruga Bay, suggesting that some type of episodic aseismic subducting motion occurred and, thus, caused a crustal movement in the overlying continental plate in the very region of the future fault zone.  相似文献   

Full-scale structural monitoring using an integrated GPS and accelerometer system   总被引：2，自引：0，他引：2  

Xiaojing Li  Linlin Ge  Eliathamby Ambikairajah  Chris Rizos  Yukio Tamura  Akihito Yoshida 《GPS Solutions》2006,10(4):233-247

Accurate in situ measurement of the full-scale structural responses, especially tall buildings, under severe loading conditions is an important requirement for validating their design, evaluating their construction as well as facilitating their maintenance. Traditionally such response has been measured using accelerometers. However, it is impossible to measure the static and quasi-static components of motion with acceleration sensors. An integrated system comprising of RTK-GPS and accelerometers has been developed with the objective of assessing full-scale structural responses by exploiting the complementary characteristics of GPS and accelerometer sensors. The data used in this paper were obtained from GPS and accelerometer sensors installed on a 108-m-high steel tower in Tokyo, together with other sensors such as anemometer and strain gauge. The seismic and wind-induced responses of the tower were analyzed using the Fast Fourier Transformation (FFT) and compared to results from finite element modeling (FEM). In order to study the system reliability, the correlated signals were extracted by applying a digital filtering technique. Then the filtered data sets were converted to displacement (in the case of accelerometer data) and acceleration (in the case of GPS data) through double integration and double differentiation, respectively, for the purpose of direct comparison and to further fuse data from the two different sensors. The results agree with each other very well, although the static and quasi-static components are missing from the accelerometer-derived results. The redundancy of the monitoring system therefore has been achieved.  相似文献   

Origin of ureilites inferred from a SIMS oxygen isotopic and trace element study of clasts in the Dar al Gani 319 polymict ureilite     

Noriko T. Kita  Yukio Ikeda  Yongzhong Liu  Yuichi Morishita 《Geochimica et cosmochimica acta》2004,68(20):4213-4235

Secondary ion mass spectrometer (SIMS) oxygen isotope analyses were performed on 24 clasts, representing 9 clast types, in the Dar al Gani (DaG) 319 polymict ureilite with precisions better than 1‰. Olivine-rich clasts with typical ureilitic textures and mineral compositions have oxygen isotopic compositions that are identical to those of the monomict ureilites and plot along the CCAM (Carbonaceous Chondrite Anhydrous Mineral) line. Other igneous clasts, including plagioclase-bearing clasts, also plot along the CCAM line, indicating that they were derived from the ureilite parent body (UPB). Thus, we suggest that some of the plagioclase-bearing clasts in the polymict ureilites represent the “missing basaltic component” produced by partial melting on the UPB.Trace element concentrations (Mg, K, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Rb, Sr and Ba) in ureilitic plagioclase and glass from 13 clasts were obtained by using the SIMS high mass resolution method. The trace element contents of the plagioclase generally show monotonic variations with anorthite content (mol%) that are consistent with partial melting and fractional crystallization. Incompatible trace element concentrations (K, Ti, and Ba) are low and variable for plagioclase with An > 40, indicating that the parental magmas for some clasts were derived from a depleted source. We performed partial melt modeling for CI and CM precursor compositions and compared the results to the observed trace element (K, Ba, and Sr) abundances in the plagioclase. Our results indicate that (1) the UPB evolved from a alkali-rich carbonaceous chondritic precursor, (2) parent melts of porphyritic clasts could have formed by 5-20% equilibrium partial melting and subsequent fractional crystallization, and (3) parent melts of the incompatible trace element-depleted clasts could be derived from fractional melting, where low degree (<10%) partial melts were repeatedly extracted from their solid sources.Thus, both the oxygen isotopic and trace element compositions of the plagioclase bearing clasts in DaG-319 suggest that the UPB underwent localized low degree-partial melting events. The partial melts could have been repeatedly extracted from the precursor, resulting in the formation of the olivine-pigeonite monomict ureilites as the final residue.  相似文献   

Interannual variations of the Hawaiian Lee Countercurrent induced by potential vorticity variability in the subsurface     

Hideharu Sasaki  Shang-Ping Xie  Bunmei Taguchi  Masami Nonaka  Shigeki Hosoda  Yukio Masumoto 《Journal of Oceanography》2012,68(1):93-111

Interannual variations of the Hawaiian Lee Countercurrent (HLCC) in the 2000s were investigated using satellite and Argo profiling float observations. The satellite-observed sea surface height shows that the geostrophic eastward current was anomalously strong to the west away from Hawaii in 2003 and 2005. However, the trade winds and the orographic wind curl dipole in the lee of Hawaii that drives the climatological mean HLCC were not particularly strong in these years, suggesting that the accelerations of the HLCC were not caused by the wind stress curl forcing around Hawaii and subsequent Rossby wave propagation. Using Argo observations, we found negative potential vorticity (PV) anomalies in the subsurface north of the HLCC in these 2 years. The pycnocline is lifted northward as low PV waters of different densities stack up in the vertical, and the HLCC is then accelerated via the thermal wind. The intensification and/or southward intrusion of the eastern subtropical mode water and subtropical mode water seem to have induced negative PV anomalies in 2003 and 2005, respectively. Using high-resolution ocean simulations, we confirmed the migrations of PV anomalies and their contributions to the HLCC accelerations. Although the HLCC is located away from the cores of major mode waters, our results suggest that interannual variations of the HLCC are affected by those of mode waters.  相似文献   

日本地震预警系统在2011年3月11日地震中的效能、不足与改进     

Yukio Fujinawa  Yoichi Noda 《国际地震动态》2015,(7)

自2007年10月以来,成熟的公共紧急地震速报(earthquake early warning,EEW)系统(国内称为地震预警系统)在日本得到应用。2011年日本东北近海(Tohokuoki)地震和海啸(也被称为3·11)发生时,震中附近的几百万人在最严重的振动发生前约15~20s,收到了地震预警(EEW)信息,同时更多周边地区的人在不太严重的振动开始前,有更多的预警时间。这些人中大约90%能够预先采取行动拯救自己及其家庭成员的生命,或根据事先计划采取其他措施,有些行为措施是基于对警报的直观反应。如此高的效率,取决于学校及社会中关于EEW系统知识的教育。尽管EEW系统存在着一些不足,但其有效性促使日本加密现有的地震与海啸监测台网。该台网在日本东部近海岛弧有约150个台站,并提供一个特殊的终端,使EEW系统更进一步应用在超过53 000名学生的学校中。当前对其分析和发布方案的改进也正在进行中。  相似文献   

Interactions between mesoscale eddy variability and Indian Ocean dipole events in the Southeastern tropical Indian Ocean—case studies for 1994 and 1997/1998     

Tomomichi Ogata  Yukio Masumoto 《Ocean Dynamics》2010,60(3):717-730

Interannual modulation of mesoscale eddy activity at the intraseasonal timescale in the southeastern tropical Indian Ocean and its relation to the Indian Ocean dipole mode (IOD) events are investigated using results from a high-resolution ocean general circulation model. The model reproduces observed characteristics of the intraseasonal variability and its interannual modulation fairly well, with large variances of the intraseasonal variability during the 1994 and 1997/1998 IOD events. Large negative temperature anomaly off the coasts of Java and the Lesser Sunda Islands in boreal summer, due to seasonal variation and interannual anomaly, extended further to the east in 1994, and the associated strong Indonesian throughflow enhanced the baroclinic instability in the upper layer, generating anomalously large mesoscale eddy activity. The eddy heat transport, in turn, significantly affected decaying phase of the 1994 IOD event. On the other hand, the development of the cold region off the Java Island associated with the 1997/1998 IOD event occurred in boreal winter, causing weaker baroclinic instability and hence weaker eddy activity off Java. This led to little influence on the heat budget in the southeastern tropical Indian Ocean for the 1997/1998 IOD event.  相似文献   

Noble gas record and cosmic‐ray exposure history of the new CO3 chondrite Moss––Comparison with Lancé and other CO chondrite falls     

Rainer BARTOSCHEWITZ  Ulrich OTT  Luitgard FRANKE  Siegfried HERRMANN  Yukio YAMAMOTO  Keisuke NAGAO  Morten BILET  Thomas GRAU 《Meteoritics & planetary science》2010,45(8):1380-1391

Abstract– The Moss meteorite is the first CO chondrite fall after a time period of 70 yr and the least terrestrially contaminated member of its group. Its cosmic‐ray exposure (CRE) age (T₃ ～ 13.5 Ma; T₂₁ ～ 14.6 Ma) is distinct among CO chondrites and, within witnessed falls is the shortest after Lancé, which we have reanalyzed. Gas retention ages are approximately 3.95 × 10⁹ yr (U/Th‐He) and approximately 4.43 × 10⁹ yr (K/Ar), respectively. Trapped Ar, Kr, and Xe are present in Moss in abundances typical for CO chondrites, with “planetary” elemental and isotopic compositions. Presence of HL‐xenon from presolar diamonds is observed in the stepwise release analysis of Lancé. It may also be present in Moss, but it is difficult to ascertain in single‐step bulk analyses. It follows from our new data combined with a survey of the literature that the abundance of trapped gases in CO chondrites is not a good indicator of their petrological subtype.  相似文献   

Particle-Image Velocimetry Measurements of Separation and Re-attachment of Airflow over Two-Dimensional Hills with Various Slope Angles and Approach-Flow Characteristics     

Isao Kanda  Yukio Yamao  Kiyoshi Uehara  Shinji Wakamatsu 《Boundary-Layer Meteorology》2013,148(1):157-175

Airflow over two-dimensional hills was investigated in a wind tunnel using particle image velocimetry. We focus on the flow separation behaviour. A trapezoidal hill shape was used in most of the experimental runs, but the critical slope angle for flow separation was approximately the same as that established for smooth hill shapes. The re-attachment point of the separated flow became farther from the hill as the slope angle $\theta $ increased, reaching a saturation of about seven times the hill height for $\theta \gtrsim 60^\circ $ . Increasing the upwind surface roughness length was found to suppress flow separation. This tendency is analogous to the previous experimental results for turbulent boundary layers on flat plates. The boundary-layer thickness varied by the presence or absence of Counihan-type spires and a castellated fence at the test-section entrance had negligible effect on the flow separation.  相似文献