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1.
C. Giraudi 《第四纪科学杂志》2004,19(6):537-545
The island of Lampedusa lies on the northern edge of the African continental shelf, but during some Quaternary marine lowstands it was joined to the African continent. The study and dating of the aeolian, alluvial, detrital sediments, calcareous crusts and speleothems have established that the climatic–environmental variations recorded on the island can be related chronologically to those known for northern Libya, Tunisia and the Italian peninsula. During the Last Glacial Maximum, phases of Saharan dust accumulation on Lampedusa occurred, and were coeval with dust accumulation in crater lakes and on high mountains in central‐southern Italy, and with phases of glacial advance in the Apennines and in the Alps. During the late Holocene, accumulation of Saharan dust on Lampedusa occurred but there was little accumulation of dust on the northern side of the Mediterranean Sea. With the new data from Lampedusa, it is possible to envisage two different scenarios of atmospheric circulation relating to the Last Glacial Maximum and to the late Holocene. During the Last Glacial Maximum, southerly atmospheric circulation brought rainfall to the southern slopes of the Alps and to the Apennines. During the late Holocene, a prevalent westerly atmospheric circulation became established in the northern Mediterranean. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
2.
小波气候突变的检测--应用范围及应注意的问题 总被引:12,自引:0,他引:12
气候突变及其检测是气候变化研究的一个重要方面。气候突变的表现多种多样,目前也有许多检测气候突变的方法,但这些方法能否准确地检测出气候突变现象,他们的适用范围如何,是一个值得注意的问题。研究表明,尽管小波分析方法在检测序列突变方面具有严格的数学意义,但因为其检测到的是序列的均值突变,因此,在应用于气候突变的检测方面应该特别注意,数学上的严格并不等同于气候意义上的严格。因为某些情况下有些突变点并没有一定的气候意义。 相似文献
3.
本文41a(1949-1989年)的资料,对东南亚10°-25°N,105°-130°E范围7-9月出现的热带风暴异常路长进行了普查统计和气候分析。结果表明:产生异常路径热风暴的机率约占区域内热带风暴总数的20%;异常路径的产生与热带风暴所处的地理位置,季节,环下等因素有关。正确地考虑气候规律和具体的天气条件相结合是预报带式风暴异常路径成败的关键。 相似文献
4.
Chemical fluxes of Asian rivers into oceans bear different regional variations. Three zones are characteristic of distinct dissolved sediment loads and yields and ionic concentration.Rivers into oceans in China play an important role in Asia because of their different chemical fluxes, among which those draining the Loess Plateau have high ionic concentration, low water discharges and dissolved sediment loads and yields.Climate, vegetation, soil and strata lithology, chemical weathering intensity and tectonic activity dominate chemical fluxes of Asian rivers into oceans, and different factors have different effects on the chemical fluxes of separate regional rivers. Rising of the Tibet Plateau also exerts an important influence on chemical compositions of rivers originating from it. 相似文献
5.
由于海岸带的地理条件和海洋动力特性的复杂性以及人类开发活动对海岸带的影响,近岸海域的生态环境系统在空间分布上有很大的变异性.基于现场实测资料,建立系统的空间变异分析模型,对海岸带生态环境空间变化规律进行分析,可以充分了解不同区域的污染特征和变化趋势.应用所构建的空间变异分析模型对渤海湾天津近岸海域的水环境特性进行分析,结合对应年份的入海流量及其变化,分析了天津渤海湾海岸带污染的主因子和区域水环境的分布特征,结果可以对海洋功能区的划分和水环境综合评价结果进行验证和补充. 相似文献
6.
In recent years, bulk carriers have been identified with high risks of catastrophic structural failure and foundering, and with heavy loss of human life. This study, based upon Lloyd's of London casualty records, identified four risk factors that had significant, independent effect upon the likelihood of a bulk carrier foundering. The risk of foundering increased with the age of the ship, and was related to the ship's flag of registration. Most importantly, however, increased risks were found for heavy cargoes of iron ore and scrap steel or iron, and for trading routes to the Far East and from Europe to North America. Additional safety measures, in particular regarding ship design and high-risk trades, may well be necessary to reduce the high casualty rates. 相似文献
7.
青藏高原腹地湖泊沉积对第四纪晚期古季风变化的响应 总被引:2,自引:0,他引:2
通过对青藏高原腹地的综合科学考察和对中心钻孔岩芯剖面的最新研究,用层序地层学与年代地层学和气候地层学相结合的方法,分辨出可可西里地区湖泊沉积记录(孔深7.25 m)的第四纪晚期距今3万余年以来的古气候变化,沉积物磁化率等因子综合表征的高原古季风变化是波动发展的,发生在仙女木期地质环境事件中的季风活动具有强烈暴发的特点,是高原季风发展中的突变事件,而且地表热点效应对其起到了激发作用。综合分析的研究成果表明,它的变化频谱与激变因子及其运行机制是伴随着青藏高原地质效应的演变而发展的,为研究第四纪冰消期以来的气候变化提供了新的信息。 相似文献
8.
A. B. Yavuz 《Environmental Geology》2006,51(2):211-227
?zmir is the third largest city in Turkey and has being the centre of art, culture, tourism and trade activities throughout the 5,000 years of its history. Natural stones brought from different parts of the world have been widely used for construction of the prestigious buildings, monuments and roads etc., in the past in the city. Renovation of the street pavements and public gathering areas in the city centre has been undertaken by the Metropolitan Municipality in 2000 and continued through the year of 2001. These renovation activities have mainly been carried out in the streets running parallel to the sea shore. Volcanic rocks brought from the Central Anatolia Ankara-Gölba?? (andesites) and Kayseri-?ncesu (tuffs) have been used in the renovation works. These rocks have shown extensive deteriorations within 4 years of their usage between 2001 and 2005 under the influence of different environmental factors. In this study, the deteriorations developed in the recently placed volcanic rocks used as kerb and pavement stones in the city centre of ?zmir in the light of their mineralogical, chemical, physical and mechanical properties, used locations and the environmental factors are presented. 相似文献
9.
矢量数字地图数据质量的综合评估 总被引:1,自引:0,他引:1
研究和确定了矢量数字地图数据的质量评估因子和评估标准,介绍了利用模糊综合评估方法进行质量评估的过程和做法,并给出了实例. 相似文献
10.