西南地区可降水量分布及其与纵向岭谷区降水的关系

利用1948-2002年NCEP/NCAR资料对西南纵向岭谷及其周边区域可降水量做EOF分解,结果表明:无论在于季还是雨季,可降水量的前两个主分量在25°N以北的纵向岭谷地区呈纬向分布特征,其时间序列均有显著的年代际变化.而纵向岭谷地区的实际降水年代际的变化并不显著,其年际变化更为清晰.降水及可降水量多雨年和少雨年的合成分析结果表明:在于季,多雨年和少雨年的可降水量与降水量均存在显著差异,并且在可降水量差值变化梯度越大的区域,降水差异越明显.在雨季,多雨年和少雨年的可降水量差别不大,但降水存在显著的差异.可见,在于季可降水量与实际降水的关系更为直接,较雨季也更为密切.     

On a dynamo driven topographically by longitudinal libration

Variation in the angular velocity Ω of a planetary body is called libration or longitudinal libration when the Ω-axis is fixed in direction. This motion of the body's solid mantle drives motions in its fluid core, either by viscous coupling across the core-mantle interface S, or topographically when S is asymmetric with respect to the Ω-axis, the only case considered in this article. A significant topographically-driven flow is identified having uniform vorticity within S and no component parallel to the Ω-axis. Its dynamic stability depends on the amplitude, Ω ₁, of the sinusoidally varying part of Ω and on the ratio, b/a, of the lengths of the principal axes of S, assumed spheroidal. In (Ω ₁/Ω ₀, b/a) parameter space where Ω ₀ is the average Ω, islands are shown to exist where the constant vorticity states are dynamically unstable. These are surrounded by a sea in which they are stable. When the fluid is slightly viscous, a state in the stable sea retains its uniform vorticity structure except in a viscous boundary layer on S in which the flow acquires a component parallel to the Ω-axis. For (Ω ₁/Ω ₀, b/a) on an island where the uniform vorticity state is unstable, an “alternative flow” exists, which is three-dimensional and is examined here. Assuming that the core is electrically conducting, kinematic dynamos are sought. Uniform vorticity flow appears to be non-regenerative but, when it is stable and viscosity acts to create a sufficiently strong boundary layer flow, dynamo action may occur. It is shown that the alternative flow that exists on an instability island in (Ω ₁/Ω ₀,?b/a) space can be vigorously regenerative.     

纵向岭谷区地表大气水汽含量的气候学计算

基于1976-2005 年30 年的高空气象逐月资料,分析了地表大气水汽含量与实际水汽压之间的统计关系,构建出基于地表水汽压的大气水汽含量气候学计算模型;结合地面气象资料,计算得到纵向岭谷区各站点的地表实际水汽压;采用ANUSPLIN气象要素插值模型,对站点地表水汽压进行空间化处理,实现地表水汽压的栅格化;最后,将地表水汽压格网数据输入构建的气候学模型,基于GIS地理空间分析平台,得到纵向岭谷区地表大气水汽含量的空间格局,实现大气水汽含量的空间化模拟。讨论纵向岭谷区地表水汽压与大气水汽含量的空间分布特征及其主要成因,认为纵向山系对水汽输送的东西向阻隔作用导致了地表水汽压与大气水汽含量的东西差异,南北走向深切河谷是季风水汽输送的重要通道;地形的“通道-阻隔”作用形成了大气水汽含量的特殊空间分布格局。     

Spatial and temporal variation of runoff of Red River Basin in Yunnan

This paper studies the variation of runoff of Red River Basin and discusses the influence of “corridor-barrier” functions of valleys and mountains on variation of runoff by using GIS and statistic methods based on the monthly precipitation, temperature and evaporation data from 1960 to 2000 at 32 meteorological stations in Red River Basin, and the annual runoff data of Yuanjiang River, Lixian River and Panlong River from 1956 to 2000. The results show out: (1) Under the effect of “corridor-barrier” functions of valleys and mountains in Red River Basin, the patterns of annual precipitation and runoff depth distribution in spatial change a NW–SE direction, which is similar with the trend of the Red River valley and Ailao mountains. (2) In the long temporal scale averaged over years, the most obvious effects of the “corridor-barrier” functions is on runoff variation, and the second is on the precipitation, but not obvious on the temperature. (3) Under the superposed effect of climate changes and the “corridor-barrier” functions of valleys and mountains in Red River Basin, the difference of runoff variation is obvious in the east–west direction: the runoff variation of Yuanjiang River along the Red River Fault present an ascending trend, but the Lixian River on the west side of the Fault and the Panlong River on the east present a descending trend; the annual runoff in Yuanjiang River and Panlong River had a quasi-5a periods, and Panlong River had a quasi-8a periods; the runoff variation are quite inconsistent in different periods among the three river basins.     

纵向岭谷区生态系统变化及西南跨境生态安全研究

位于我国西南、以纵向山系和大河为主体特征的纵向岭谷区,其地表主要自然物质、能量输送和人类活动等,表现出明显的“通道—阻隔”作用,产生了复杂多样的关联效应：使其成为亚洲大陆主要的纵向生物走廊、避难所和我国与东南亚重要的生态廊道,拥有北半球除沙漠和海洋外的各类生态系统,是全球生物物种的高富集区和世界级基因库,但其生态脆弱、灾害频发;主导了区内多民族沿河谷分布、在山间盆地聚居的“大分散、小聚居”格局,其社会经济发展地域分异大。因此,该区一直是地学和生物学等研究地表复杂环境系统与生命系统演变规律的关键地区,在全球具有不可替代性;同时,该区资源富集,短期开发行为多、环境退化加剧、贫困普遍,保护与发展矛盾极为突出,在西部具有典型性和代表性。     

中国西南纵向岭谷区孢粉空间组合对阻隔作用的指示意义

35 surface soil samples and 28 profile soil samples were collected in Longitudinal Range-Gorge Region, Southwest China. The distribution of pollen and spores and their relationship with the environment are analyzed. The results show that there are significant differences in pollen and spores taxa, amounts, dominant taxa and florae between the eastern and western flanks of the Ailao Mountain. There are more pollen and spores taxa, a greater amount and complexity on the western flank of the mountain than those on the eastern flank, while the dominant taxa are more centralized and prominent on the eastern flank of the Ailao Mountain. As for the plant florae distribution, there are significant differences in the number of taxa and composition between the eastern and the western flanks. The analysis of profile pollen and spores assemblage shows that its trends of variation are basically in accordance with the surface pollen and spores, which are also indicators of the environmental differences between the two flanks of the mountain. These significant spatial differences of pollen and spores are very close to the regional topography and climate difference. The mountain running perpendicular to the moisture-laden air flow serves as a barrier and the monsoon circulations the east and the west of the mountain result in different energy-moisture characteristics. We conclude that the main patterns of the pollen and spores can be attributed to the environmental differences.     

基于RV指数的道路网络干扰效应空间分异研究——以云南省纵向岭谷区为例

不同尺度下道路网络干扰效应空间分布差异研究及其驱动因子识别,对进一步研究道路网络引起的生态系统演变具有重要意义.利用表示道路网络干扰效应的RV(Roadless Volume)指数.以云南省纵向岭谷区为案例区.在不同尺度上分析了道路网络干扰效应的空间分布差异.结果表明,云南省纵向岭谷区道路网络干扰效应总体呈现中部高、两边低的趋势:地州及县域尺度上,干扰效应主要集中在昆瑞公路沿线的地州及县市;流域内部分区尺度上,各个流域的中下游地区干扰效应较强;流域尺度上,红河流域相比其他流域干扰效应强.进一步的相关性分析表明,道路网络干扰效应受生态承载力、道路密度和海拔高度等因素的驱动.     

Time constraints for the evolution of a large slope collapse in karstified mountainous terrain of the southwestern Crimean Mountains, Ukraine

Prominent longitudinal features are often reported on the surfaces of mass movement deposits. However, the genesis and implications of these have not hitherto been considered, and herein we present preliminary observations of their occurrence both in the field and in the laboratory. Elongated ridges are often oriented (sub-) parallel to the flow direction and aligned radially from the source due to debris spreading. They are particularly prominent in large (> 10⁶m³) rock avalanches emplaced onto deformable substrates and are also found in the proximal reaches of volcanic debris avalanches. Flowbands, which are longer and thinner expressions of longitudinal ridges, are continuous along the entire flow length and are observed in rock avalanches emplaced onto glaciers, in snow and some ice avalanches, in pyroclastic flows and some block-and-ash flows, in ejecta sheets, in extraterrestrial landslides, and in some volcanic debris avalanches. Other volcanic debris avalanches and the distal areas of rock avalanches often display hummocks that are aligned radially from the source; we propose that these aligned hummocks are remnants of longitudinal ridges. The formation of elongate ridges (and their expressions as flowbands, aligned hummocks, or distal lobes and digits) in qualitatively-similar fashion in both laboratory and field environments suggests they represent an intrinsic tendency of granular flows in a wide range of situations.     

基于形变观测分析中国台湾东部花东纵谷断层运动特征

花东纵谷断层是中国台湾动力作用和地壳运动变形最强烈的断层之一,其断层运动特征和强震危险程度一直备受学者的关注。文中分别以同震地表位移、1992-1999年震间形变数据为约束,反演2003年成功MW 6.8地震同震位错分布和花东纵谷断层震间运动特征。结果表明：花东纵谷断层北段处于强闭锁状态（闭锁率高达0.9）,闭锁深度深（约27 km）;南段闭锁程度较弱（闭锁率约0.5）,闭锁深度较浅（约12 km）;中段闭锁程度与闭锁深度介于南北段之间。另一方面,2003年成功MW 6.8地震微观震中位于震间无震滑移区与闭锁区的过渡带附近。依据同震位错、震间断层运动反演结果,以及历史强震破裂分布特征,分析认为,花东纵谷断层南北段运动方式存在差异性,北段主要以强震形式运动,南段以蠕滑和地震两种形式运动。自1951年花莲-台东ML 7.3地震序列后,花东纵谷断层南段、中段和北段至2016年所累积的矩能量分别等价MW 6.4、MW 7.0、MW 7.4地震;若发生级联破裂,整个断层至2016年所累积的矩能量等价MW 7.5地震。     

顶部电离层离子密度经度结构的特征及其随季节、太阳活动和倾角的变化

本文利用DMSP卫星测量数据和傅里叶分解和重构方法,研究了地磁平静期顶部电离层总离子密度(Ni)经度结构的多重波数特征及波数4的年变化、逐年变化、地方时差异和随倾角的变化.傅里叶分解和重构的结果表明,顶部电离层平均Ni的经度结构中同时含有以波数1至波数4为主的多重分量,不同波数分量的幅度和相位各不相同.对波数4分量的分析表明,波数4的幅度在春秋季最强,北半球夏季高于冬季;随太阳活动水平增强,波数4分量的幅度增高,至太阳活动高年幅度达到最高,此后随太阳活动水平降低而减小,与F10.7呈正相关;春秋季和北半球夏季波数4分量在傍晚最强,晚上和上午次之,黎明最弱,从09LT到21LT,波数4的相位依次滞后,暗示向东移动.分析还发现,日落期间波数4幅度依赖倾角,春秋季随倾角的变化呈双峰结构,两个极大出现在倾角±18°附近,暗示赤道等离子体喷泉效应对顶部电离层经度结构的控制作用.