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1) I. A. H. S. / A. I. H. S.

Abstract

A simple method is used to study the response of runoff in the Sahel to climate change. The statistical characteristics of rainfall are calculated over the western part of the Sahel for the period 1961–1990, using the BADOPLU network. Daily rainfall is simulated using a Markov process with Weibull distribution for rainfall depths. Runoff is modelled using a conceptual SCS model and the curve numbers are calculated for West Africa. Climate change is provided by simulations using the Arpège GCM (Scenario A1B), and a perturbation method is used on the parameters which describe the rainfall. Changes in rainfall are assumed to occur through increases in frequency, not intensity. Using Arpège, runoff is mainly found to increase, in depth and in number of events, by the end of the 21st century. Changes in evaporation and land use are not included in the analysis. The impact of this 21st century potential climate change (rainfall) on the runoff is found to be of the same magnitude as the impact of changes in land use.     

DOT2008A海面地形模型在我国邻近海域的精度评估

文中首先介绍了DOT2008A模型建立的原理和方法,利用我国48个长期验潮站19 a连续观测数据验证DOT2008A模型的精度,其均方差为0.118 m,残差的标准偏差为0.086 m;联合多源测高卫星建立的海面地形模型数据验证DOT2008A的精度,均方差为0.106 m,残差的标准偏差为0.099 5 m,且其残差分布图基本符合正态分布。从实验结果来看,DOT2008A模型在我国周边海域精度较高,其建立方法较为合理,转化应用价值较高;同时与多源测高卫星建立的海面地形比较结果来看,验证了自主建立的海面地形模型的正确性,对建立我国高精度海面地形模型具有重要的借鉴意义。     

潮汐强度与咸潮上溯距离试验

采用物理模型实验方法对不同潮差驱动下咸水入侵距离进行实验研究,结果表明存在潮差临界值使得咸水入侵距离最短,当潮差小于该临界值,咸水入侵距离随潮差增大呈快速减小趋势,而大于该临界值则呈缓慢增大趋势。基于实验数据对盐淡水混合进行理论分析,揭示了实验现象的产生机制:①潮差增大过程中盐淡水混合由高度分层变为均匀混合,导致驱动咸潮入侵的动力发生了改变;②当盐淡水为弱混合类型,盐淡水高度分层,重力环流输运是盐进入河口的主要方式,潮汐强度增大减小了盐淡水分层,减弱了重力环流的输运作用,因此入侵距离变小;③当盐淡水为强混合类型,盐淡水混合均匀,重力环流输运作用大大减弱,潮汐扩散成为主要的输运方式,潮汐增强使得扩散能力增大,因此潮汐强度越大,咸潮入侵距离越大。     

Darkness on the Edge of Town: Mapping Urban and Peri-Urban Australia Using Nighttime Satellite Imagery

This article explores the use of nighttime satellite imagery for mapping urban and peri-urban areas of Australia. A population-weighted measure of urban sprawl is used to characterize relative levels of sprawl for Australia's urban areas. In addition, the expansive areas of low light surrounding most major metropolitan areas are used to map the urban–bush interface of exurban land use. Our findings suggest that 82 percent of the Australian population lives in urban areas, 15 percent live in peri-urban or exurban areas, and 3 percent live in rural areas. This represents a significantly more concentrated human settlement pattern than presently exists in the United States.     

The Orbital Evolution of Two Sounding Satellites and Analysis of the Accuracy of Orbit Determination

The satellites TC-1 and TC-2 are the two Chinese satellites with great elliptical orbits which are still in orbit around the earth at present. Since the launch the orbits of the two satellites have continuously evolved, which has a certain effect on the orbit determination and prediction precision. The regularities of the orbital evolution of the two sounding satellites are qualitatively and quantitatively analyzed. Under the current tracking mode the corresponding prediction precision of orbit determination is analyzed based on the different stages of the orbital evolution, thereby providing the basis for the adjustment of planning mode by the satellite application departments and the guarantee of normal satellite payload. Finally, the orbital lifetimes of the two satellites are predicted through the trend of the orbital evolution.     

川北砂岩-泥岩系混合作用地球化学特征

根据沉积岩混合作用判别原理,应用元素铬－钍判别法,判明川北砂岩－泥岩系为二元混合成因。再根据二元混合元素丰度关系定律,由混合变换式求出丰度关系常数,认为川北砂岩－泥岩系既具有互稀释混合作用,又具有稀释混合作用,进而可以对沉积岩端员物质组成进行估算。     

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拉果错盐湖卤水蒸发过程中Li+富集行为的分子动力学模拟(英文)

采用分子动力学模拟,研究了西藏拉果错盐湖卤水中阴、阳离子以及水分子间的相互作用行为。以盐湖卤水等温蒸发过程中粒子浓度变化的四个阶段为研究对象,分别计算了不同体系的扩散系数、配位数、均方位移和径向分布函数。计算结果表明,液相浓度越低时,H₂O分子对各离子之间的相互作用有抑制作用,液相中离子浓度越高时,SO₄^2-易与CO₃^2-竞争Li⁺形成离子对,从而影响盐湖卤水中Li⁺的富集。本文研究结果对盐湖卤水中Li⁺的迁移行为作出了机理解释,为盐湖卤水提锂的发展奠定了理论基础。     

驱动重联过程中等离子体团的聚合

本文对驱动重联过程作了二维可压缩磁流体动力学模拟．对于长的计算域（１：４）,在持续入流的作用下形成了双重磁岛结构,这些磁岛在向外运动的过程中不断靠近,逐渐聚合成为一个大的等离子体团,并继续向外运动．这说明在地球磁层顶和磁尾所观测到的大尺度磁结构,很可能是在驱动重联过程中,由较小的等离子体团聚合后形成的．并初步揭示了在空间等离子体中,磁岛的聚合过程难以直接观测的动力学原因．