基于“DEM-NDVI-土地覆盖分类”的天山博格达自然遗产地山地垂直带提取与变化分析

本文基于Landsat影像数据获取天山博格达自然遗产地土地覆盖分类,结合归一化植被指数（NDVI）和数字高程模型（DEM）构建“DEM-NDVI-土地覆盖分类”散点图分析研究区植被受海拔和坡向的水热空间变化影响的分布特征,通过概率统计分析提取博格达遗产地山地垂直带,并结合研究区的气温、降水数据和NDVI变化特征分析垂直带变化的原因。研究结果表明：① 本文利用“DEM-NDVI-土地覆盖分类”散点图,揭示了研究区1989年和2016年的NDVI值和分类类别随着海拔上升的变化特征,其中NDVI值随着海拔上升呈现“倒U形”变化,而不同分类类别在一定的海拔区间内呈现出聚集效应,且不同分类类别有明显的高程界限。② 1989年和2016年博格达遗产地山地垂直带分带上限分别为：1278 m和1185 m（温带荒漠草原带）、1784 m和1759 m（山地草原带）、2706 m和2730 m（山地针叶林带）、3272 m和3293 m（高山草甸带）、3636 m和3690 m（高山垫状植被带）。③ 博格达遗产地1989年和2016年山地垂直带受区域气温升高和降雨增加的影响有较为明显的改变,其中温带荒漠草原带最为敏感,其上限变化最大,向下收缩93 m;山地针叶林带的分布范围则向两侧扩张49 m;山地草甸带带宽基本保持不变,但整体上移了约20 m;冰雪带则受到全球气候变暖的影响向上退缩54 m。     

"10.19"全州冰雹的中小尺度分析

用天气学方法对1997年10月19日全州县境内出现的一场历史上罕见的冰雹过程的中小尺度进行分析,揭示这次过程的一些机制,为掌握冰雹发生前中小尺度系统的活动和演变规律积累经验,对提高今后的预报服务能力将有所帮助.     

Early J2 basalts in SE China: Incipience of large-scale late Mesozoic magmatism

Magmatism in SE China was dormant during 204–180 Ma, but was reactivated in 180–170 Ma (early J₂), and then became more and more intensive towards the end of early Cretaceous. The small-scale early J₂ magmatism is the incipience to long-term and large-scale magmatism in this region. A near east-west (EW) trend volcanic belt was distributed across south Hunan, south Jiangxi and southwest Fujian was formed during early J₂ time. Along this belt from the inland toward the coast, the lithology of basalts changes from alkali into tholeiite, and the amount of erupted volcanic rocks and the proportions of rhyolites coexisting with the basalts increase. On the basis of geochemical characteristics of these basalts, we infer that the melting degree of source rocks and the extent of fractional crystallization and crustal contamination all increased whereas the depth of mantle source decreased from the inland to the coast, which led to the variations of geological characteristics of the volcanic belt. In early J₂, the western spreading Pacific plate began to subduct underneath SE China continental block, reactivating near EW trend deep fault that was originally formed during the Indosinian event. The stress of the western spreading Pacific plate and the extent of asthenosphere upwelling increased from the inland to the coast, which is consistent with the generation and evolution of early J₂ basalts.     

包头市昆都仑水库增雨燃烧炉首次作业的效果分析

通过2009年5月27日包头市昆都仑水库地面增雨燃烧炉作业实况和多普勒天气雷达速度、713天气雷达回波及区域地面自动雨量站资料的对比分析,发现在深厚的层状云系中,适时进行地面燃烧炉增雨作业,可增强区域降水量,提高增雨作业能力。分析结果为指导包头地区地面燃烧炉布点和增雨作业提供了科学依据。     

鄂温克旗干旱、洪涝灾害期评定及预测方法

根据鄂温克旗1959—2008年气象历史资料,统一归类,并采用统计预报方法,简要评定预测出鄂温克旗50年来主要气象灾害之一的干旱、洪涝灾害期,为鄂温克旗防范旱涝灾害做参考。     

被动陆缘盆地陆隆斜坡对盐构造形成的影响 ——来自物理模拟实验的启示

被动陆缘盆地盐构造形成的影响因素及时空演化分析受到了国内外学者的高度重视.丰富的油气资源促进了被动陆缘盆地地震资料品质的不断提升,高精度地震数据的解译结果表明,被动陆缘盆地盐层下的地形往往具有大型的起伏特征,而前人在基底构造形态对盐构造形成影响方面的研究并未取得共识,仍需要深入研究和探讨.为此,本文基于前人的研究认识,...     

海水中微量元素无机离子交换动力学研究——液膜递进模型理论 Ⅰ.天然海水条件下

最近十几年来,海水物理化学中关于海水的化学热力学研究已较广泛地开展,并已有一些重要的研究结果报导。但是,关于海水中化学动力学的研究,至今却基本上仍属空白。然而这正是海洋中许多化学过程(特别像海水化学资源开发、海洋污染和防治等实践性比较强的领域中)要解决的关键问题。本文是我们从事这一方面研究工作的第一篇报导,讨论的内容是海洋中最重要的过程之一——无机离子交换过程。     

Occurrence and characteristics of sporadic sodium layer observed by lidar at a mid-latitude location

Na lidar observations of SSL during the past 5 years at a mid-latitude location (Wuhan, China, 31°N, 114°E) are reported in this paper. From 26 SSL events detected in about 230 h of observation, an SSL occurrence rate of 1 event/9 h at our location was obtained. This result, combined with that reported by Nagasawa and Abo (Geophys. Res. Lett. 22 (1995) 263) at Tokyo, Japan, reveals that the SSL occurrence can be relatively frequent at some mid-latitude locations. The statistical analyses of main parameters for the 26 SSL events were made, and the results were compared with those previously reported. By examining the corresponding data from a nearby ionosonde, it was found that there was a fairly good correlation between SSL and Es. Of the 18 pairs of SSL and Es events checked, 15 of SSL were accompanied by Es, and 8 pairs of them were correlated within 1 h in time and within 5 km in altitude. From the analyses of observed perturbations during SSL development, the role of dynamic processes of atmosphere in the SSL formations were emphasized.     

一种新的极化SAR图像非监督分类算法研究

提出了一种建立在Mean-shift过分割结果区域图上的极化SAR图像非监督分类算法。首先通过Mean-shift算法得到极化SAR图像的过分割结果区域图,并将过分割小块视为“超级像素”,然后在Freeman-Durden分解的基础上引入散射功率熵和各向异性量参数来进一步分析“超级像素”的混合散射机制问题,最后结合Wishart迭代聚类实现极化SAR图像的非监督分类。实验表明,该算法具有较为满意的分类效果。     

陕西镇巴火焰溪法门阶牙形刺研究

陕西镇巴火焰溪剖面位于大巴山西段，临近川陕交界、交通便利。那里晚泥盆世地层出露完好，层序清楚，化石丰富。本文就该剖面法门阶牙形刺动物群、泥盆系石炭系的界线进行了研讨，建立了该区法门阶的两个浅水相牙形刺生物组合带。