冬季地面温度和500hPa高度场的适应关系及其客观诊断

实况资料表明,冬季地面的距平高温(或低温)往往对应于高空的距平高压(或低压)。为此,本文建立了一个地面温度距平和500 hPa高度距平之间只带一个比例系数的适应模式。如果这个比例系数看作坐标的函数,它比用常数作比例系数的适应模式更能反映客观实际。     

哀牢山-红河剪切带的热年代学研究——多重扩散域模式的应用实例

洛弗拉等人(1989)把Dodson(1973)建立的单一扩散域模式扩展成矿物扩散域不连续分布的模式,即多重扩散域模式,与之对应具有某一封闭温度范围,因此利用单个K-长石矿物样品可以揭示更长时间段上的冷却过程。对云南哀牢山-红河剪切带的K-长石样品(FA-2-1)进行40Ar/39Ar同位素分析,利用多重扩散域模式,揭示在距今约20～19Ma问该带存在一快速冷却过程,这与西藏南部曲水地区快速抬升的时间是一致的     

Numerical case study of the Altai-Sayan lee cyclogenesis over East Asia

Summary Climatological studies show that the Altai-Sayan lee side is one of the major cyclogenesis areas in the Northern Hemisphere. In case of the Altai-Sayan lee cyclogenesis, the surface cyclone is generated when a primary cyclone is swept north of the mountains. In the mid-troposphere, a trough develops and finally turns into a cutoff low within 48 h. The main synoptic features are similar to those of Alpine cyclogenesis. Numerical simulations are performed to assess the effect of different representation of orography on the Altai-Sayan cyclogenesis. Two experiments are performed, a step-mountain (ETA) and an envelope orography (SGM) experiment. The ETA experiment produced the cyclogenesis in a way similar to that in the analysis both at the surface and at mid-troposphere. The SGM experiment failed in the simulation of the upper cutoff low. The difference in predicted pressure between the ETA and the SGM experiment shows a dipolar structure suggesting that the blocking effect of the mountains is essential in the development of the Altai-Sayan lee cyclogenesis.With 7 Figures     

Dynamical interpretation of observed plasmasphere deformations

Based on all of the OGO-5 light ion density measurements (covering the period from March, 1968 to May, 1969), a definition of “isolated plasma regions” was employed to locate the most prominent patches of enhanced light ion densities in the midst of the depleted region, outside of the main plasmasphere. On the dayside, the distribution of these isolated plasma in L.T. vs. L coordinates was quite similar to that of the “detached plasma regions” by Chappell (1974a). On the nightside, however, the new distribution revealed more frequent occurrence of these regions. Elongated thick plasmatails produced during periods of sudden enhancement of convection electric fields and subsequentially thinning and corotating of the plasmatails during quieting periods, in general, could account for the statistical distribution as well as the individual events, such as those between March 27 and April 2, 1968 and Oct. 21 and Oct. 24, 1968. As demonstrated by Kivelson (1976), wave-particle interactions could produce tremendously complicated structures observed in the near vicinity of the plasmapause and far away from the plasmasphere. Examination of H⁺ and He⁺ density measurements for period of Aug. 12–Aug. 20, 1968 indicated that the density reduction of the plasmasphere during a magnetic storm was on the same order of magnitude as that obtained from whistler techniques during a magnetospheric substorm.     

荒漠植被红砂（Reaumurta soongorica）水热响应的年轮学研究

 红砂是黄土高原荒漠植被带主要建群植物种之一，在植被恢复重建和生态建设中具有重要意义。本文以皋兰县40 a天然植被封育区为例，运用树木年轮学方法，对不同坡向红砂与当地水热条件变化的时空响应及分布格局进行了研究。研究结果表明，红砂具有明显的年轮特征，可以进行树木年轮方面的研究。虽然不同坡向水分条件和植被状况有很大差异，但红砂径向生长对区域水热变化具有非常一致的响应模式：同生长季降水呈正相关关系，尤以7月降水量最为显著；同生长季气温呈负相关关系，以6月最为显著。根据不同坡向红砂年龄分布格局分析结果，并考虑到水土流失的防治效果，黄土高原西部荒漠植被带的封育期限不宜少于10 a。     

Impact of Flood Disasters on Taiwan in the Last Quarter Century

The increasing natural disasters, especially floods during the last quarter century, are raising the economic losses in Taiwan. The most severe hazard in Taiwan is flooding induced by typhoons and storms in summer and autumn. By comparing the rivers around the world, the ones in Taiwan have the steepest slopes, the largest discharge per unit drainage area, and the shortest time of concentrations. Rapid urbanization without proper land uses managements usually worsen the flood problems. Consequently, flood hazards mitigation has become the most essential task for Taiwan to deal with. Although the government keeps improving flood defense structures, the flood damage grows continuously. In this article, possible flood mitigation strategies are identified for coping with complex environmental and social decisions with flood risk involved.     

加固含水平软弱层高陡边坡预应力锚索倾角的取值范围

用直线和曲线滑面两种模型，模拟预应力锚索加固含有水平软弱层的高陡边坡的潜在滑动面，通过对锚索加固的力学机理分析来阐述预应力在滑动面主滑方向上产生分力的原因。从锚索受力角度上对锚索倾角的取值范围进行探讨，结合实际造孔过程有不同程度的孔斜或弯曲以及获取较好的锚固灌浆效果，就仰角锚固和俯角锚固两种锚固条件分别得出锚索倾角的取值范围，并以此来判定锚索的预应力是否会在滑动面走向方向上产生不利于坡体稳定的下滑力。     

南极菌Pseudoalteromonas sp．S-15-13产胞外多糖的研究及其分子鉴定

本文对影响南极细菌S-15-13生长和胞外多糖产量的主要环境因子进行了研究,同时采用16S rDNA序列分析及系统发育分析方法对其进行了分子鉴定。结果表明：菌株S-15-13最佳产糖条件为：培养时间,56h；培养温度,8℃；碳源,1．0%葡萄糖；NaCl浓度,3．0%；pH,6．0-7．0。16S rDNA序列分析和系统发育分析表明,菌株S-15-13属于假交替单胞菌属(Pseudoaltero- monas)。     

Climatic characteristics of summer high temperature and assessment methods in the large cities of North China

Based on the high temperature data of June to August in 1961-2000 in North China, the high temperature weather processes are investigated, and a more complete data set for severe high temperature processes is created. The climatic characteristics of adverse high temperature weather in Beijing, Tianjin, Shijiazhuang, Jinan and Taiyuan are analyzed respectively. The major features of the East-Asia Subtropical High and Transformed Continental High are discussed. The outcomes indicate that the influence of both East Asia Subtropical High and Transformed Continental High on these weather events varies, by a larger margin, from one city to another over North China and they are also closely related to the relative humidity. It is found that the behaviours of East-Asia Subtropical High and Transformed Continental High are the major important systems that give rise to the summer high temperature weather over the region. Based on these findings, the 5-day, 10-day and monthly assessment models for such high impact events have been developed. The assessment outcomes prove to be useful in assessing severe high-temperature events in major cities of North China.