200hPa非地转风和非均匀层结与梅雨暴雨的关系

本文通过1991年梅雨后期，7月1—13日200hPa非地转场分析得出，梅雨期200hPa非地转风主要由积云对流动量转换形成。其次是风速平流，并通过数值试验得以证明。非地转风形成的高层辐散，可进一步使暴雨增强与维持。另外梅雨期非均匀层结对非地转风及暴雨也有较大的影响。     

心象地图在制图传输中的作用

制图传输是制图学的重要研究领域。本文从认知制图的角度,探讨了心象地图在制图传输中的作用;着重分析了心象地图和地图之间的内在联系,指出了人的认知制图能力的客观存在是制图传输得以进行的真正原因;在此基础上,提出了制图传输的扩展模式,增加了从读图者到次读图者之间的传输过程,并从内容和形式等方面分析了它的特殊性,以期完善制图传输模式。     

A simulation model of blowout development

Blowouts are the main feature of wind erosion in the dunes along the Dutch coast. A number of characteristics, such as their growth against the prevailing wind and the spontaneous stabilization when certain dimensions are reached, are believed to be caused by a prominent quality of the southwest wind, viz. its gustiness. This hypothesis is tested in a two-dimensional computer model which simulates the effect of wind gusts on a sandy surface along the main axis of the blowout. A number of constraints based on field observations are built into the model. The results closely resemble the longitudinal section of the blowout.     

时空变化风场中声重波波包的演变

本文从可压缩情况下的流体力学方程出发,采用多重尺度方法和W.K.B.方法,研究时空变化风场中声重波波包的演变过程。文中导出了声重波波长、相速、传播方向以及振幅的演变方程。结果表明,沿群路径上波长、相速和传播方向的变化取决于风场的时空变化以及风场与波的相对方位。此外,波振幅的演变方程还表明:在时空慢变风场中,声重波的波作用量具有守恒性,声重波波包能量增加伴随波频率增高,声重波波包能量减小伴随频率降低。能量变化的实质是,风场的时变性引起了波流相互作用。     

航空甚低频电磁异常在胶东牟乳地区构造填图中的应用

通过对胶东牟平－乳山地区１：２．５万航空甚低频电磁异常的分析研究，并结合航磁，航放、遥感以及区域构造地质资料，进行了构造地质填图，首次进一步证实了被前人所忽视的近东西向断裂构造的存在，并给予了准确定位。在此基础上进行了金矿成矿远景预测，取得了比较满意的效果。     

A simultaneous interpretation,by wind speed and direction,of ambient air negative ion density in Athens,Greece

A recently developed data presentation technique, the rectangular wind frequency isopleth diagram, has been applied to examine the effect of wind speed and direction, acting simultaneously, on ambient air negative ion densities. The large negative ion concentration decreases in the majority of directions and wind speed intervals, while that of the small ions increases, as the wind speed increases. The local maxima and minima, occurring in some sectors, are properly discussed.     

Wind ripples in an active drift sand area in the Netherlands: A preliminary report

Two types of wind ripples are distinguished in an active drift sand area near Hulshorst in The Veluwe (Central Netherlands). The common type has amplitudes of about 0·5 cm and wavelengths of some 11 cm, the atypical ripple has amplitudes of about 1 cm and wavelengths of some 16 cm. In both cases, the sand grains in the crests are coarser than those in the troughs. However, the coarseness of the grains in the crests of the higher ripples is much more pronounced than that of the lower. It is tentatively suggested that wind ripples are initiated by a regular downwind alternation in the impact energy of the descending grains in saltation, possibly due to fixed gravity waves in the sheared flows of air with grains which have strong density gradients with height.     

The temporal and spatial development of landslides in the axmouth-lyme regis undercliffs national nature reserve,Devon

A chronology of landsliding is presented, including suggestions as to a date for initiation. Periods of activity known from historical sources are correlated with known periods of climatic deterioration. The current morphology of the landslide slopes is closely related to the geological succession and structure. These permit the landslides and their development to be differentiated on the basis of whole slope and toe morphology, and much of the whole-slope activity can be related to conditions at the toe. Examples of geomorphological maps, slope categories maps, and cross sections are presented along with an example of the ‘evolutionary’ maps which may be derived from Ordnance Survey plans and aerial photographs. These generally indicate that weakening of materials by weathering, seepage erosion at the toe, and marine erosion result in frequent mass movement events of a low magnitude. These events ultimately influence the stability of larger slipped blocks behind, which fail less frequently. It is suggested that whole-slope failures in this region have a maximum frequency of once in 120 to 150 years, and that problems of interpretation of historical accounts may mean that it is very much less frequent than this.     

Inverted-polarity electrical structures in thunderstorms in the Severe Thunderstorm Electrification and Precipitation Study (STEPS)

Balloon-borne electric field soundings and lightning mapping data have been analyzed for three of the storms that occurred in the Severe Thunderstorm Electrification and Precipitation Study field program in 2000 to determine if the storms had inverted-polarity electrical structures. The polarities of all or some of the vertically stacked charge regions in such storms are opposite to the polarities observed at comparable heights in normal storms. Analyses compared the charge structures inferred from electric field soundings in the storms with charges inferred from three-dimensional lightning mapping data. Charge structures were inferred from electric field profiles by combining the one-dimensional approximation of Gauss's law with additional information from three-dimensional patterns in the electric field vectors. The three different ways of inferring the charge structure in the storms were found to complement each other and to be consistent overall. Charge deposition by lightning possibly occurred and increased the charge complexity of one of the storms.Many of the cloud flashes in each case were inverted-polarity flashes. Two storms produced ground flash activity comprised predominantly of positive ground flashes. One storm, which was an isolated thunderstorm, produced inverted-polarity cloud flashes, but no flashes to ground. The positive and negative thunderstorm charge regions were found at altitudes where, respectively, negative and positive charge would be found in normal-polarity storms. Thus, we conclude that these storms had anomalous and inverted-polarity electrical structures. Collectively, these three cases (along with the limited cases in the refereed literature) provide additional evidence that thunderstorms can have inverted-polarity electrical structures.