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931.
石笋与环境— — 石笋纹层形成的环境机理初探 总被引:19,自引:6,他引:19
石笋沉积的生长条带从剖面图式可分为两大类: 一类没有明确的沉积旋回界面,难以按层计数,称为“生长纹理” ; 另一类具有确定的沉积旋回界面,可以按层计数,称为“生长层理”。石笋生长层理可以发展成为一类重要的断代工具。中国北方型微层的形成可能主要与干湿季变化明显的气候条件、以及富含有机质和碱性交换态离子的土壤类型密切相关。而南方型微层的形成可能主要与较长时间的降水和有机质淋滤以及盛夏高温-少降水的配置有关。如果沉积物中某种要素对物源或水流通过路径的环境变化能够灵敏反应,并按一定的时间单元将这些变化记录下来,就能成为高分辨的气候— 环境变化信息库。 相似文献
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浙江古田山自然保护区常绿阔叶林群落特征 总被引:1,自引:0,他引:1
在对古田山自然保护区森林植被广泛调查的基础上,详细分析了常绿阔叶林群落特征,从该区森林植被的外貌特征、群落结构和种类组成上看,均具有我国典型亚热带常绿阔叶林的基本性质。 相似文献
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Jinsong Pan Daigao Teng Fuqing Zhang Lingli Zhou Ling Luo Yonghui Weng Yunji Zhang 《中国科学:地球科学(英文版)》2018,61(5):572-594
The characteristics and dynamics associated with the distribution, intensity, and triggering factors of local severe precipitation in Zhejiang Province induced by Super Typhoon Soudelor (2015) were investigated using mesoscale surface observations, radar reflectivity, satellite nephograms, and the final (FNL) analyses of the Global Forecasting System (GFS) of the National Center for Environmental Prediction (NCEP). The rainfall processes during Soudelor’s landfall and translation over East China could be separated into four stages based on rainfall characteristics such as distribution, intensity, and corresponding dynamics. The relatively less precipitation in the first stage resulted from interaction between the easterly wind to the north flank of this tropical cyclone (TC) and the coastal topography along the southeast of Zhejiang Province, China. With landfall of the TC in East China during the second stage, precipitation maxima occurred because of interaction between the TC’s principal rainbands and the local topography from northeastern Fujian Province to southwestern Zhejiang Province. The distribution of precipitation presented significant asymmetric features in the third stage with maximal rainfall bands in the northeast quadrant of the TC when Soudelor’s track turned from westward to northward as the TC decayed rapidly. Finally, during the northward to northeastward translation of the TC in the fourth stage, the interaction between a mid-latitude weather system and the northern part of the TC resulted in transfer of the maximum rainfall from the north of Zhejiang Province to the north of Jiangsu Province, which represented the end of rainfall in Zhejiang Province. Further quantitative calculations of the rainfall rate induced by the interaction between local topography and TC circulation (defined as “orographic effects”) in the context of a one-dimensional simplified model showed that orographic effects were the primary factor determining the intensity of precipitation in this case, and accounted for over 50% of the total precipitation. The asymmetric distribution of the TC’s rainbands was closely related to the asymmetric distribution of moisture resulted from changes of the TC’s structure, and led to asymmetric distribution of local intense precipitation induced by Soudelor. Based on analysis of this TC, it could be concluded that local severe rainfall in the coastal regions of East China is closely related to changes of TC structure and intensity, as well as the outer rainbands. In addition, precipitation intensity and duration will increase correspondingly because of the complex interactions between the TC and local topography, and the particular TC track along large-scale steering flow. The results of this study may be useful for the understanding, prediction, and warning of disasters induced by local extreme rainfall caused by TCs, especially for facilitating forecasting and warning of flooding and mudslides associated with torrential rain caused by interactions between landfalling TCs and coastal topography. 相似文献
938.
碳公平的测度:基于人均历史累计排放的碳基尼系数 总被引:3,自引:0,他引:3
以人均历史累计排放为基础,借用了收入分配公平的研究思路,以洛仑兹曲线和基尼系数为指标,尝试以一个综合性的指标测度排放空间中的分配公平问题。对碳基尼系数的分析表明,目前70%的排放空间被用于不公平分配,其分配差异同目前收入差异最悬殊的国家在同一水平上,解决碳公平问题迫在眉睫。基于人均累计排放的碳基尼系数可以用以度量碳排放空间的不平等,并为国际社会对碳公平的讨论提供一个量化的指标。 相似文献
939.
In order to improve the spatial uniformity of rainfall generator to natural rainfall uniformity, according to the rotation of the test platform, a rotary test platform was designed and developed, and the slip-ring was used to solve the problem of signal transmission in the process of the rotation. Besides, the relationship between rotational speed and spatial uniformity of rainfall generator was established. The results of tipping-bucket rain gauge tested in rainfall field and flow type rainfall intensity standard device testing demonstrated that rainfall generator as the rainfall accumulation and rainfall intensity of the test environment was feasible. Results showed that with the increase of the rotate speed, spatial uniformity first increased, and then decreases, and with the decrease of the test area, different speed presented different trends. When the rotational speed was 1 RPM, test area was 1.6 m×1.6 m and 1.2 m×1.2 m, its uniformity of rainfall generator reached maximum which was bigger than 95%; with the increase of the rotate speed, tipping-bucket rain gauge of RA and RI were of good consistency under the RPM 1 and RPM 2 and the RA maximum deviation reached minimum, 0.2 mm; the average of RA under flow type rainfall intensity standard device test consisted well with rotating test platform at speed RPM 1 and 2, which illustrated the rotary testing platform was consistent with the flow type rainfall intensity standard device. It showed that the method to improve the space uniformity of rainfall generator is feasible and it could find the dynamic difference of RA. 相似文献
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