用TRMM卫星微波成像仪资料遥感地面洪涝的研究   总被引：4，自引：4，他引：4  

姚展予  李万彪  高慧琳  朱元竞  赵柏林  张强 《气象学报》2002,60(2):243-249

文中阐述了用热带降雨测量卫星 (TRMM )微波成像仪 (TMI)监测地面洪涝灾害的能力 ,并利用动态聚类、土壤湿度指数、极化亮温差指数、极化亮温比指数等 4种基于TMI亮温资料的方法遥感了 1998年夏季中国江淮流域的洪涝灾害。通过与机载雷达图像、星载雷达图像以及基于地面日降雨量资料的Z 指数方法确定的地面洪涝情况的对比 ,结果表明用TMI亮温资料监测地面洪涝灾害是可行的 ,遥感结果也是比较满意的  相似文献   

Seasonal changes of microbial populations in the sediments of the basins of Lugano and Agno     

Raffaele Peduzzi  Antonella Demarta  Mauro Tonolla 《Aquatic Sciences - Research Across Boundaries》1992,54(3-4):331-337

This research was carried out with the aim to explore the heterotrophic microbial population of two sediments in different oxic conditions of the Lake of Lugano (Lago di Lugano). The values of the viable bacterial counts found in our sediment samples were typical for an eutrophic lake.The increase in the proportion of anaerobic to aerobic bacteria at 30 °C observed in the sediment samples of Agno may reflect the depletion of oxygen concentrations in the water column.The generaAeromonas, Pseudomonas, Bacillus andClostridium, as well as strains belonging to the Coryneform-group, represented the major taxonomic groups of heterotrophic bacterial communities in the water-sediment interface.  相似文献   

Chemistry and trophic evolution of Lake Lugano in relation to nutrient budget   总被引：1，自引：0，他引：1  

Alberto Barbieri  Rosario Mosello 《Aquatic Sciences - Research Across Boundaries》1992,54(3-4):219-237

Chemical studies performed in the last 50 years on the northern and southern basins of Lago di Lugano are reviewed and discussed in relation to the phosphorus and nitrogen loads from the drainage area.Both basins became eutrophic in the fifties as a consequence of the dense population and industrial activity in the drainage area; the effect of these was aggravated by the meromictic condition of the layer below 100 m in the northern basin.The reduction of phosphorus loads in progress since 1976 has resulted in a significant improvement in the chemical and biological condition of the southern basin and the upper 100 m of water in the northern basin. On the other hand, the balance between dissolved oxygen and reducing substances in the northern basin is shifting toward a decrease of the net oxygen concentration, partly as a consequence of the unusually dry conditions of the last three years.A reduction in phosphorus load down to 18 and 22 t a^–1 in the northern and southern basins respectively is still necessary in order to reduce the lake phosphorus concentration to 30–35 µg O l^–1.  相似文献   

The Fate of Chernobyl137Cs in Lake Lugano     

J. Dominik  D. Span 《Aquatic Sciences - Research Across Boundaries》1992,54(3-4):238-254

A rapid removal of Chernobyl¹³⁷Cs from a number of large lakes has been previously reported. Our measurements of¹³⁷Cs in water, sediments and pore water in the mono- and meromictic basins of Lake Lugano (Lago di Lugano) reveal generally slower half-removal times of 1.2 and 6.7 yrs, respectively. In the seasonally anoxic southern basin, this is most probably related to an intensive recycling of¹³⁷Cs between water and sediments. In the permanently stratified northern basin the removal rate is much slower due to an important inventory build up in the deep anoxic part of the basin.  相似文献   

Role of pigments on algal communities and photosynthesis   总被引：2，自引：0，他引：2  

A. Lami  P. Guilizzoni  D. Ruggiu  B. Polli  M. Simona  A. Barbieri 《Aquatic Sciences - Research Across Boundaries》1992,54(3-4):321-330

A one-year study of phytoplankton, primary production and related physical and chemical factors was made in a Swiss basin of Lake Lugano (Lago di Lugano). The chlorophylls and 12 carotenoids were analyzed with a TLC technique. The carotenoid monitoring was considered to be particularly interesting, because the role of these pigments in freshwater algae is still very poorly documented by field studies. The dependence of photosynthesis on several factors was statistically evaluated. Evidence was found of light-adaptation phenomena. The variations of photosynthetic activity and efficiency largely depended on the light regime in the few days before the field observations and on the cellular content of chlorophylls and single carotenoids, whose concentrations in their turn were closely linked with light, temperature, average cell size, and with the actual species assemblage.  相似文献   

准两年振荡与青藏高原东北侧旱涝   总被引：1，自引：0，他引：1  

田荣湘 《高原气象》1992,11(3):321-327

  相似文献   

Synmetamorphic veining: origin of andalusite-bearing veins in the Vedrette di Ries contact aureole, Eastern Alps, Italy   总被引：1，自引：0，他引：1  

B. CESARE 《Journal of Metamorphic Geology》1994,12(5):643-653

Discordant andalusite-biotite-quartz-bearing veins occur in the contact aureole of the Vedrette di Ries pluton (Italian Eastern Alps), never outside the area of contact metamorphic andalusite development. Andalusite veins are found only within andalusite-bearing hornfelses, and vein biotite occurs wherever host-rock garnet is partially replaced by biotite. Veins formed during contact metamorphism, synchronously with the crystallization of andalusite and biotite within host rocks. Their pegmatitic structure and their orientation suggest that vein parageneses crystallized within fluid-filled cavities that opened by hydraulic fracturing. A mechanism of synmetamorphic veining is proposed to explain rock failure and subsequent mineral deposition within veins. During hydrofracturing induced by dehydration reactions in response to heating in the aureole, fissures were immediately filled with locally derived fluids. The lack of large-scale flux, together with high fluid pressures required by hydrofracturing, suggest fluid in the cavities was a virtually stagnant, passive medium, and that mass-transport toward fractures was driven by intergranular diffusion. Because temperature and P_f values within veins are similar to those in the host rock, vein assemblages are interpreted as the stable, high-T side of reactions taking place within pelitic schists, at the time when fractures opened. Once nucleation of product phases occurred, chemical components released by dissolution of reactant minerals were driven to precipitation sites by chemical potential gradients. Since nucleation was favoured at the strained grains of vein walls, andalusite and biotite simultaneously grew in vein and host rock. The proposed genetic model contrasts with generally adopted metasomatic mechanisms for the genesis of Al₂SiO₅-bearing veins, in not requiring large fluid/rock ratios or a highly ‘aggressive’ fluid composition. The mechanism of synmetamorphic veining may be particularly useful in the interpretation of vein occurrences in medium- and deep-crustal rocks which have undergone extensive devolatilization.  相似文献   

洪涝灾害的本底数据库构建方法   总被引：3，自引：0，他引：3  

毕建涛池天河  何建邦 《地球信息科学学报》2003,5(4):22-24

采用一种新的方法和作业流程 ,通过利用 Par GIP并行遥感图像处理软件 ,以及 Arc GIS等软件对洪涝灾害地区建立遥感动态监测的本底数据库 ,包括遥感影像数据及矢量数据 ,为快速进行灾害的监测与评价提供基础与条件 ;通过在鄱阳湖地区的试验 ,使洪灾的监测评价速度和效率成倍提高。  相似文献   

季风区边缘近500年的降水变化特征     

刘敬华  张平中  孟彩红  张德忠  杨勋林 《地理科学》2011,31(4):401-407

基于武都万象洞高分辨率石笋δ¹⁸O和高精度²³⁰Th定年数据,结合利用周边地区史料恢复的旱涝指数序列,重建季风区边缘近500 a以来降水变化。结果显示:在年际至百年时间尺度上,万象洞石笋δ¹⁸O变化指示亚洲季风带来的降水量信息。季风区边缘降水变化可分减弱期(1470~1700 A.D.)、平稳期(1701~1875 A.D.)和增强期(1876~2003 A.D.)三个气候段,其间季风降水的强弱变化响应史料记载的极端旱涝事件。在小冰期向20世纪暖期转换过程中,本区呈现阶梯式过渡降水模式,这是一种较大空间尺度上气候特征,在年代际至百年时间尺度上与北半球温度、中国温度变化具有同步性。  相似文献   

Understanding the collapse–eruption link at Stromboli,Italy: A microanalytical study on the products of the recent Secche di Lazzaro phreatomagmatic activity     

Chiara M. Petrone  Eleonora Braschi  Lorella Francalanci 《Journal of Volcanology and Geothermal Research》2009

The Secche di Lazzaro (SDL) phreatomagmatic activity, with the associated Neostromboli sector collapse, represents the most powerful activity of the last 6 ky at Stromboli. As revealed by its present-day activity, Stromboli is one of the most eruptive volcanoes in Italy, and flank instability, along its NW flank, is a common process. Volcano instability is often dramatised by explosive eruptions, thus it is of crucial importance to understand the linking between volcano collapse and the plumbing system itself. The possible role of pre-eruptive magmatic processes as triggers of explosive eruptions can be mainly preserved by minerals and revealed by petrochemical studies. We studied the juvenile components (scoria and pumice) of the pyroclastic deposits from the SDL phreatomagmatic activity with the aim to understand the eruption–collapse link.  相似文献