大气Rossby波动力学的研究进展

Rossby波是旋转大气和海洋中的一类重要波动,在天气和气候演变中起有重要的作用。该文介绍了北半球中纬度地区的两类重要Rossby波——斜压不稳定波和准定常行星波,在最近20余年来取得的一些重要研究进展。文中涉及的主要研究领域有:斜压不稳定波包动力学、湿斜压过程对斜压不稳定波的作用、北半球风暴轴动力学、斜压波包与高影响天气的预报、准定常行星波的形成机理、准定常行星波的水平传播与能量频散、准定常行星波的垂直传播与能量频散、三维准定常行星波的传播与能量频散。     

ANALYSIS OF RAINSTORMS ASSOCIATED WITH SIMILAR TRACK TROPICAL CYCLONES HAITANG (0505) AND BILLS (0604)

It is generally thought that the influence of comparable track typhoons is approximately similar,but in fact their wind and especially their rainstorm distribution are often very different. Therefore,a contrastive analysis of rainstorms by tropical cyclones (TCs) Haitang (0505) and Bilis (0604),which are of a similar track,is designed to help understand the mechanism of the TC rainstorm and to improve forecasting skills. The daily rainthll of TC itaitang (0505) and Bills (0604) is diagnosed and compared.The result indicates that these two TCs have similar precipitation distribution before landtall but different precipitation characteristics after landthll. Using NCEP/GFS analysis data,the synoptic situation is analyzed; water vapor transportation is discussed regarding the calculated water vapor flux and divergence.The results show that the heavy rainfall in the Zhejiang and Fujian Provinces associated with Haitang (0505) and Bitis (0604) before landlhll results ti'om a peripheral easterly wind,a combination of the tropical cyclone and the terrain. After landthll and moving far inland of the storm,the precipitation of Haitang is caused by water vapor convergence carried by its own circulation; it is much weaker than that in the coastal area. One of the important contributing thctors to heavy rainstorms in southeast Zhejiang is a southeast jet stream,which is maintained over the southeast coast. In contrast,the South China Sea monsoon circulation transports large amounts of water vapor into Bills - when a water-vapor transport belt south of the tropical cyclone significantly strengthens - which strengthens the transport. Then,it causes water vapor flux to converge on the south side of Bilis and diverge on the north side. Precipitation is much stronger on the south side than that on the north side. After Bilis travels far inland,the cold air guided by a north trough travels into the TC and remarkably enhances precipitation. In summary,combining vertical wind shear with water vapor transportation is a good way to predict rainstorms associated with landing tropical cyclones.     

Three‐dimensional steady‐state response of a railway system on layered half‐space soil medium subjected to a moving train

The paper presents a three‐dimensional study on the steady‐state response of a track system and layered half‐space soil medium subjected to the load induced by the passages of a moving train with the substructure method. Practically, due to the ground water table being several meters beneath the ground surface, the soil profile can be divided into two layers: the upper layer modeled by an elastic medium and the lower layer by a fully saturated poroelastic medium governed by Biot's theory. In the meanwhile, the rails are regarded as an infinitely long Euler beam, and the sleepers are represented by a continuous mass. The effect of the ballast is accounted for by introducing the Cosserat model for granular medium, and the train is described by a series of moving axle point loads, depending on the geometry of the train. The influences of the thickness, the mass and the rigidity of the elastic layer and the mass of the ballast on rail's displacement responses are carefully investigated. Numerical results show that the influences of these parameters are significant for high train velocity, while vanishes for low velocity. Copyright © 2008 John Wiley & Sons, Ltd.     

A new Cenomanian vertebrate tracksite at Tamajón (Guadalajara,Spain): Palaeoichnology and palaeoenvironmental implications

A new Upper Cretaceous vertebrate tracksite has been discovered at Tamajón (Iberian Ranges, Guadalajara, Spain). The track level is a relatively smooth and slightly undulating sandy ferruginous crust, corresponding to an erosive surface at the base of a small meandering channel. It is incised into the underlying planar cross-bedded sandstones of coastal bars located at the middle-upper part of the Utrillas Formation (middle-upper Cenomanian). The site shows an extraordinary concentration of vertebrate tracks, among which numerous sets of two to five isolated digit impressions (“swim tracks”) and, at least, two trackways referred to crocodyliforms, and a single tridactyl footprint probably produced by a theropod dinosaur can be recognized. There are also several long traces (epichnial grooves) revealing sharp direction changes (up to 90°) which seem to be fish fin traces (Undichna unisulca), although crocodyliforms (tail marks) and/or fish invertebrates cannot be rejected as possible tracemakers. Some crocodyliform tracks reveal a thin raised rim, due to the displacement of the sediment by the pressure produced by the feet. Several impressions are moderately deformed by small sediment slides, only preserving their deepest part (claw marks). This is clearly indicative of a soft substrate with a high degree of plasticity and water content at the time of the track registration. Nevertheless, the sediment was hard enough to preserve manus and pes print morphologies and also possible crocodyliform tail and/or fish fin traces. Small rhizoliths can also be recognized and may belong to herbaceous wetland vegetation. The morphology of the palaeochannel, the sedimentary context and the track preservation seem to indicate that the tracks were impressed in a shallow channel located near the coast, under wet conditions and in different moments of time. This discovery represents the first occurrence of vertebrate ichnites in the Utrillas Formation, a stratigraphic unit where osteological and ichnological remains are relatively scarce, and it confirms that some crocodyliforms lived in near coast channels during the deposition of this unit.     

南海台风路径预报试验

利用预测误差平方和最小准则的逐步算法对台风路径进行拟合和预测试验，试验结果表明ＰＲＥＳＳ方法得到的模型具有较强的预测能力，因而，ＰＲＥＳＳ方法同逐步回归一样，也是一种预报台风路径客观有效的方法。     

Counting fission tracks in mica external detectors

The different ways in which minerals and external detectors respond to chemical etching are outlined. While it is prossible that the distribution of angles of inclination of fission tracks in some materials can be determined from the measurement of the aspect ratios of the etch pits this cannot be done using mica detectors. A method of measuring the distribution of angles of inclination in mica detectors based on the frequency distribution of areas of fission track entry holes is proposed. The results of two experiments are presented, and a means of correcting the number of tracks lost during etching is described.     

石英环带结构填图有效性研究—以胶东乳山金矿为例

本文在胶东乳山金矿热液石英环带结构研究基础上，提出了一种新的矿物学填图参数，即石英环带韵律数。试验表明，石英环带韵律数等值线图可以反映热液活动的轨迹，并能指示矿质富集的地段。     

稳定切变形势下的降水量级预报

６月份，浙西地区有１／５的大到暴雨过程出现在７００ｈＰａ上武汉和长沙一带为偏北风的形势下。该文提出了其中主要的稳定切变形势的定量描述因子及其降水量级的预报方法。     

异常气候对高寒区杏树生产的影响及对策

杏树是雁北高寒区主栽果树品种之一，也是当地农民脱贫致富的重要收入来源。异常气候是影响当地杏树栽培优质丰产的主要障碍因素。通过近年来山西省阳高县异常天气对杏树生产的影响的分析调查，提出了相应的生产管理措施，对高寒区杏树优质丰产具有一定的指导意义。     

阜新经济转型期水资源开发潜力研究

阜新市是一个矿产资源枯竭、水资源极度缺乏的国务院确定的经济转型试点城市,即由煤炭资源开发为主转向以现代农业为主.面对地区水资源短缺的现实,如何开发、利用和配置水资源是决定转型是否成功的关键.本文对地区水资源状况进行了分析,并提出了水资源开发利用潜力.