A NUMERICAL STUDY ON THE FORMATION AND DEVELOPMENT OF ISLAND-INDUCED CYCLONE AND ITS IMPACT ON TYPHOON STRUCTURE CHANGE AND MOTION

In this paper,the impact of the Taiwan Island topography on the structure change and motion ofTyphoon Dot(9017)during its crossing the Taiwan Island is studied with a modified version of aJMA operational regional model(Japan spectral model,JSM).A series of sensitivity experiments areconducted to detect the forming and developing mechanism of an island-induced cyclone.Results showthat lee side low pressure center plays a very important role in the formation of the induced-cyclonewhile a typhoon is approaching a large island with high mountains.The position and intensity of theinduced cyclone is sensitive to the height and location of island mountain,intensity of TC and under-lying surface topography distribution as well.A preliminary formation criterion of the island-inducedcyclone is obtained.     

东海与黑潮海水中宇宙射线成因核素10Be的研究

讨论了中日东海MASFLEX合作计划中调查的东海及冲绳海槽海水中溶解态10Be浓度水平及垂直剖面的结果，在这个海区，影响10Be浓度的因素主要有生物生产力，悬浮颗粒物的再溶解，以及长江水与黑潮水的混合程度。在样品采集期间（夏季和秋季），东海水柱呈分层状态，通常10Be的垂直剖面可以分成三层，即表面混合层，10Be释放层和底层，表层水10Be的浓度众长江口到黑潮逐渐增大，在黑潮的边缘则剧烈增大，10Be的垂直分布表明，在夏季10Be富集在长江口附近和大陆架中部的底层水中，这两个富集海区是分开的，很可能是由大陆沿岸水所隔开，在秋季，10Be在底层水中的富集仅仅出现在东海大陆架的西部，这个现象是和受季风影响的东海海流的变化相一致的，黑潮分支在台湾东北外海向东海南部侵入对10Be的影响要比黑潮主干流本身更加重要显著，由箱式模型所得到的10Be质量平衡计算结果表明，来自黑潮的10Be输入要比长江及大气沉降的输入更为重要，输入东海的10Be大约81％进入到沉积物中，而19％的10Be则通过海流和水交换流出东海，在东海的10Be沉积通量是10Be全球平均大气生产率的5倍左右，因而东海是10Be的一个重要汇集地。     

Equatorial field-aligned irregularities deduced from the echo-train and hybrid whistlers

Summary Equatorial field-aligned irregularities have been studied by using low-latitude echotrain and hybrid whistlers observed at Sakushima Station (geomag. lat. 24°). The structure is discussed in relation to the propagation mode trapped by field-aligned irregularities. We then find that the field-aligned irregularities responsible for the trapping of low latitude whistlers are of such small dimension as the HF ducts.     

Analysis of tubular steel bridge piers

A one‐dimensional model is proposed for the static and dynamic analysis of tubular steel bridge piers subjected to strong ground motions. The present formulation does not require experimental results nor shell analysis to obtain the constitutive equation of the model, which shows strength deterioration. The material properties and dimensions of bridge piers are required for static and dynamic analysis of the present model. The present analysis consists of two steps. The first step is to obtain the stress and strain relationship of the base plastic‐hinge region, where local inelastic buckling is observed. The modified Shanley's model and fiber elements are used to establish the compressive skeleton curve. The strength deterioration is taken into account in the resulting constitutive model. The second step is to analyze static and dynamic responses of tubular steel bridge piers. For overall analysis, the base plastic‐hinge region is discretized in the circumferential direction by using fiber elements whose constitutive equation was obtained in the first step. The validity of the present model has been confirmed through comparisons with existing experimental results. Copyright © 2005 John Wiley & Sons, Ltd.     

Meteorological features in Adélie Land during the austral summer season

Intensive meteorological observations were carried out at three sites along the slope of Adélie Land, Antarctica, with the goal of documenting summertime meteorological features of the katabatic zone. Three observational sites were placed at 5 km (D10), 110 km (D47), and 210 km (D57) from the coast, and frequency distributions of meteorological parameters were obtained at each site. Some meteorological features at D47 and D57 (interior sites) were different than at D10 (the coastal site); namely, mean air temperatures averaged for the whole observational period showed more pronounced diurnal variations at the interior sites than at the coastal site. These variations could be represented by sinusoidal curves. Wind speeds also showed diurnal variations, whose extremes appeared several hours later than the temperature extremes. The prevailing wind direction for all sites was southerly, about 30° east of the fall line, with small variations in wind direction. The strength and the height of temperature inversions were examined in two different layers (0 to 50 m, 50 to 300 m) at D47. A strong, shallow inversion layer formed at night, however, completely vanished during the day. On the other hand, an upper level inversion whose strength was weak persisted. The katabatic characteristics of the surface wind found at D47 in summer could be due to this upper level temperature inversion.A contribution to I.A.G.O. (Interaction-Atmosphere-Glace-Ocean).     

Incorporation of Be isotopes and other trace metals into marine ferromanganese deposits

Two-to threefold inward increase of ¹⁰Be, ⁹Be, Cu and Ni have been found in surface layers of marine ferromanganese deposits. We interpret this phenomenon as reflecting the manner in which the Be isotopes and probably other trace metals (e.g. Cu and Ni) are incorporated. On reaching the sea floor exchangeable Be is released from its carrier phase to the pore water of the ferromanganese deposits, diffuses inward and gets fixed into the deposits. The fixation process may be related to the mineralogical reorganizations suggested by previous studies. We have modeled this concept and applied it to a Mn crust on which detailed analyses of Cu, Ni and natural decay-series nuclides, as well as Be isotopes are made. Post-depositional fixation of Th isotopes may also occur. The redistributions of Be and Th isotopes are confined to regions very close to the surface of the deposits. For all practical purposes, they will not affect growth rate determinations conventionally done using these isotopes. The “linearly” extrapolated ${}^{10}\text{Be}{}^9\text{Be}$ ratio to the surface from deep layers of a Mn deposit does not necessarily represent that ratio in sea water.     

Radiative characteristics in a Japanese forested drainage basin during snowmelt

Radiative characteristics in a forested drainage basin during the snowmelt season were examined in order to better understand and predict snowmelt runoff in the basin. A method for estimating net radiation in a forest (R_nf) was presented using the total sky view factor (P) and the sun path sky view factor (Q). Solar radiation, albedo, atmospheric radiation and air temperature observed at an open site were also required. The total and the sun path sky view factors were determined from all‐sky photographs. Q was expressed as a linear function of P for 0·15<P<0·86 regardless of forest type. For P<0·15, Q was set to zero, and for P>0·86, Q was equal to unity. The short‐wave radiation budget at the forest floor (S_nf) increased with P, whereas the long‐wave radiation budget (L_nf) decreased with P. R_nf increased with P for 0·15<P<0·86, and changed little with P for P<0·15 and P>0·86, as the increase in S_nf was offset by the decrease in L_nf . The forest effect on R_nf was diminished under cloudy or high albedo conditions, because S_nf was easily offset by L_nf . This estimation method was extended to the whole basin, and R_nf was obtained over a watershed covered by trees. At the beginning of the snowmelt season when the albedo remained high, the forest effect became null because the decrease in S_nf was balanced by the increase in L_nf . As the albedo gradually lowered with the advance of the snowmelt season, the decrease in S_nf owing to forest covers exceeded the increase in L_nf , and the forest effect to decrease R_nf became evident. Copyright © 1999 John Wiley & Sons, Ltd.     

岩石磁组构可以揭示应变吗？——以华南地块早三叠世灰岩为例

一般认为磁组构能有效地反映岩石所经历的应变特征.为了研究不同类型的磁组构和不同期次应变之间的关系,对来自华南地块两个地区的早三叠世灰岩样品进行了岩石磁学、磁组构以及应变特征的对比分析.来自湖北通山县的样品经历了三期构造变形,这为解析磁组构和多期次应变提供了理想的机会.岩石磁学结果显示携磁矿物主要为磁铁矿.磁化率各向异性（AMS）和非磁滞剩磁各向异性（AAR）结果显示其最小轴与层面垂直,最大轴和中间轴分布于层面内,反映了沉积和压实作用产生的应变,而后期构造应变在磁组构中没有体现.来自广东连县的样品发育有渗透性压溶缝面理和方解石脉,说明经历了构造应变.AMS结果没有显示占优势的组构方向.AAR结果显示三轴组构,其最大轴分布于最大应力方位,与构造应变特征吻合,最初的压实组构被构造应变组构所代替.上述结果表明：（1）AAR可以很好地反映渗透性应变的特征,而AMS有时会失效;（2）应变的尺度要小于样品的尺度,磁组构才能有效地反映应变.     

A nonlinear parametric model based on a power law relationship for predicting the coastal tsunami height

When a subduction-zone earthquake occurs, the tsunami height must be predicted to cope with the damage generated by the tsunami. Therefore, tsunami height prediction methods have been studied using simulation data acquired by large-scale calculations. In this research, we consider the existence of a nonlinear power law relationship between the water pressure gauge data observed by the Dense Oceanfloor Network System for Earthquakes and Tsunamis (DONET) and the coastal tsunami height. Using this relationship, we propose a nonlinear parametric model and conduct a prediction experiment to compare the accuracy of the proposed method with those of previous methods and implement particular improvements to the extrapolation accuracy.