Winnie(9711)台风变性加强过程中的降水变化研究

热带气旋变性过程是其结构、强度及其风雨分布发生显著变化的过程,常导致预报失败。基于T106格点分析资料、日本气象厅TBB资料以及MM5V3数值模式结果,对9711号台风Winnie变性加强过程中的降水变化特征及其机理进行研究。结果表明,Winnie台风变性加强过程中降水分布非对称性明显,强降水带首先出现在台风环流北部,之后向南弯曲,其强降水中心绕台风中心从北部顺时针转向东北和东南部。这种降水变化一方面与Winnie与西风带高空槽相互作用过程中环境风垂直切变明显增大,且其指向顺时针旋转有关。此间台风垂直结构发生明显倾斜,变性前期涡旋环流随高度增加先向北倾斜,发展到最强时又趋于垂直,之后又向东南倾斜。强降水区出现在垂直切变的下风方、台风气柱倾斜方向一侧。另一方面还与台风环流内冷、暖平流活动紧密相关,强降水落区与低层暖平流输送位置关系密切。对流涡度矢量垂直分量反映了Winnie台风环流内中尺度锋区与风垂直切变的相互作用,800 hPa上的大值区对其强降水落区有较好的指示意义。     

塔里木盆地西北缘埃迪卡拉纪—寒武纪转折期黑色岩系中硅质岩成因及其环境指示意义

埃迪卡拉纪—寒武纪转折期是地质历史上的关键期,全球范围内普遍发育一套黑色岩系,包括硅质岩、泥岩和白云岩。在这套黑色岩系中下部,发育了不同厚度的硅质岩,尤其是在塔里木盆地西北缘,黑白燧石条带韵律性互层且硅质岩分布变化大,其成因对寒武系玉尔吐斯组优质烃源岩形成环境具有重要指示意义。本文以塔西北地区新柯地1井这套黑色岩系中硅质岩为研究对象,运用岩芯观察、镜下薄片鉴定、主微量元素和稀土元素分析,研究硅质岩与有机质的成因及其二者之间的共生机理,硅质岩较高的Ti、V、Y、Ba等元素含量、较低的δ30Si值(1. 2‰~0. 7‰)、明显的Ce负异常说明其硅质流体为热液来源,但是硅质岩不是热液脉体侵入形成,而是富含硅质的流体与冰冷的海水混合沉积而成,硅质岩沉积受温度、pH值、有机质等因素共同控制,有机质的存在可以促进硅质沉淀。同时系统地研究了黑白燧石条带韵律性互层的成因,白色层由纯的微晶石英组成,而黑色层由碎屑碳质颗粒、石英颗粒和碳质纹层组成,认为是微生物席活动的结果,硅质岩中黑白燧石层受冰期和间冰期控制。硅质岩中较高的Al2O3/(Al2O3+Fe2O3)比值和较低的Lan/Cen比值代表受陆源影响的大陆边缘沉积环境,结合古气候、海平面变化等信息,认为塔西北地区寒武系玉尔吐斯组硅质岩以及硅质页岩沉积于局限海湾或潟湖环境,为正确认识硅质页岩的形成环境和烃源岩的评价预测提供理论指导。     

基于雷达特征参数的贵州中西部雹云单体跃增特征分析

利用2016-2019年贵州省人工影响天气作业站点上报信息、市（州）的灾情快报,以及毕节、贵阳、兴义3部新一代多普勒天气雷达资料等,分析贵州中西部7个具有多阶跃增特征的雹云单体的雷达参数演变特征,研究发现：（1）二阶跃增冰雹云演变呈发展-跃增-降雹-减弱-再发展-跃增-降雹的趋势;（2）降雹时刻,雹云的最大反射率因子（MaxREF）、45dBz回波高度（H45dBz）、回波顶高（H0dBz）、垂直累积液态水含量（VIL）平均值分别为63.4 dBz、7.55km、12.01km、39.08 kg/m2;大冰雹对应的MaxREF和VIL较小冰雹更大,大冰雹、小冰雹的H45dBz差别不大,大冰雹对应的H0dBz反而小于小冰雹;（3）冰雹发生前,MaxREF、H45dBz、H0dBz和VIL两个体扫间平均最大跃变分别为：5.89 dBz、2.19km、2.82km、17.5 kg/m2,跃变现象的出现比冰雹发生时刻平均提前21.4、22.2、28、28.8min,可以作为冰雹发生前的重要判断依据。     

中国与全球能源网络的互动逻辑与格局转变

当前中国正处于从油气时代向可再生能源时代转变的关键时期,中国能源需求结构和能源利用形式的变化决定了中国与全球能源的互动逻辑发生了深刻转变。为更好理解中国与全球的能源互动过程,本文探讨了全球能源互动的基本理论认知,并借助复杂网络、投入产出分析等技术方法分析了中国与全球能源互动格局及其变化。研究发现中国与全球能源互动的范围不断扩大,程度不断加深,从油气贸易到可再生能源贸易,从油气为主的投资到多元化能源品种的投资,从传统能源贸易到隐含能源贸易等方面,中国逐渐塑造了多元化的全球能源格局。主要结论为：① “多煤少油缺气”的能源生产结构和巨大的油气需求,决定了保障海外油气供应是中国与全球能源互动最直接的逻辑,互动区域主要集中在油气富集的国家和地区。② 随着可再生能源的发展,中国与全球能源互动逻辑从单纯的油气贸易转变为涉及可再生能源相关产品的贸易,凭借制造业优势,互动范围从油气富集的国家和地区拓展到全球拥有可再生能源发展和装机需求的国家,形成了覆盖全球主要国家和地区的可再生能源贸易新格局。③ 中国的海外能源投资目标从有限数量的东道国扩展到欧洲、东南亚等国家和地区,投资业务不仅局限在油气领域,也扩大到太阳能、风能和水能等可再生能源发电项目及电网等基础设施建设投资。④ 中国作为全球制造业大国和贸易大国,在全球化程度加深的背景下,部分能源隐含于全球生产网络和贸易网络中进行二次分配,中国与全球能源互动范围进一步拓展到与中国具有一般商品贸易关系的国家和地区,形成了全球“能源中枢”的功能。本文可为深刻认识中国与全球的能源互动关系,维护国家能源安全和参与全球能源经济治理提供理论视角与决策依据。     

接触型与非接触型犯罪时空稳定性对比及其联合防控——以盗窃和电信网络诈骗为例

近年来,以盗窃为代表的接触型犯罪和以电信网络诈骗为代表的非接触型犯罪均呈多发态势,严重影响社会治安稳定。已有研究对不同类型犯罪分布模式的时空稳定性关注仍不够,且未能提出不同类型犯罪的空间联合防控策略。本文以ZG市HT区为例,以社区为分析单元,运用核密度估计、时空跃迁测度法等方法,对比分析2017年盗窃犯罪和电信网络诈骗犯罪的时空分布特征及其空间分布模式的月度稳定性,并从犯罪防控角度改进时空跃迁测度法,结合二阶聚类法识别两类犯罪联合防控空间类型。研究发现：① 两类犯罪时空稳定性差异大,盗窃犯罪的空间分布模式稳定,月度变化小;而电信网络诈骗犯罪空间稳定性整体波动起伏大,月度变化较大;② 识别出两类犯罪的四种联合防控空间类型,分别是“两类犯罪无需防控社区”“两类犯罪邻域防控社区”“盗窃犯罪热点防控、电信网络诈骗犯罪无需防控社区”“盗窃犯罪连片防控、电信网络诈骗综合防控社区”。该研究有助于了解接触型犯罪和非接触型犯罪时空特征的共性和差异性,给警务联合防控提供决策支持。     

Dynamic changes and transitions of agricultural landscape patterns in mountainous areas: A case study from the hinterland of the Three Gorges Reservoir Area

Analyzing the agricultural landscape patterns in mountainous areas is critical to clarify the dynamic changes and development direction of agricultural landscapes. This also plays a significant role in the rational planning and management of agricultural land. A theoretical framework for agricultural landscape pattern transitions in mountainous areas is proposed to fill the gap of current research with an empirical study in the Caotangxi Watershed, Three Gorges Reservoir Area (TGRA), China. The transition characteristics of agricultural landscape patterns from 2000 to 2018 as represented by sloping farmland, abandoned land, and orchards are analyzed from a holistic-local perspective. The results indicate that the orchards expanded along river valleys, and abandoned land expanded at high elevations, which led to reduced sloping farmland. This phenomenon gives regional landscape differences at the holistic and local levels. Namely, it enhances the region’s holistic landscape diversity but causes fragmentation and aggregation of landscape patches in local areas. The agricultural landscape pattern transitions within the farming range in the study area are manifested primarily in four modes: sloping farmland-orchard conversion type (FOCT), comprehensive conversion type (CCT), partially abandoned type (PAT), and wholly abandoned type (WAT). Each transition mode reveals different development stages of the mountainous agricultural landscape patterns. In general, the agricultural landscape pattern transition is driven by socioeconomic factors in mountainous areas of the TGRA and is bidirectional. This attribute is expressed as the transition from the traditional grain-planting landscape with an even distribution to the eco-economic win-win orchard in valleys and transitions from sloping farmland to abandoned land in high-elevation areas. Overall, the results of this study reveal the uniqueness of agricultural landscape pattern evolutions in China’s mountainous areas in recent decades, which has enlightened the in-depth understandings of rural land use and agricultural ecosystems in mountainous areas of the TGRA, as well as improvements in rural developments and ecological environments.     

Holocene development of maritime ombrotrophic peatlands of the St. Lawrence North Shore in eastern Canada

Macrofossil analyses were used to reconstruct long-term vegetation successions within ombrotrophic peatlands (bogs) from the northern shorelines of the St. Lawrence Estuary (Baie-Comeau) and the Gulf of St. Lawrence (Havre-St-Pierre). Over the Holocene, the timing and the ecological context of peatland inception were similar in both regions and were mainly influenced by fluctuations in relative sea level. Peat accumulation started over deltaic sands after the withdrawal of the Goldthwait Sea from 7500 cal yr BP and above silt–clay deposits left by the Laurentian marine transgression after 4200 cal yr BP. In each region, the early vegetation communities were similar within these two edaphic contexts where poor fens with Cyperaceae and eastern larch (Larix laricina) established after land emergence. The rapid transitions to ombrotrophy in the peatlands of Baie-Comeau are associated with particularly high rates of peat accumulation during the early developmental stage. The results suggest that climate was more propitious to Sphagnum growth after land emergence in the Baie-Comeau area. Macrofossil data show that treeless Sphagnum-dominated bogs have persisted over millennia and that fires had few impacts on the vegetation dynamics. This study provides insight into peatland vegetation responses to climate in a poorly documented region of northeastern America.     

Holocene history and environmental reconstruction of a Hercynian mire and surrounding mountain landscape based on multiple proxies

We discovered the first peat section covering the entire Holocene in the Hrubý Jeseník Mountains, representing an island of unique alpine vegetation whose history may display transitional features between the Hercynian and Carpathian regions. We analysed pollen, plant macrofossils (more abundant in bottom layers), testate amoebae (more abundant in upper layers), peat stratigraphy and chemistry. We found that the landscape development indeed differed from other Hercynian mountains located westward. This is represented by Pinus cembra and Larix during the Pleistocene/Holocene transition, the early expansion of spruce around 10,450 cal yr BP, and survival of Larix during the climatic optimum. The early Holocene climatic fluctuations are traced in our profile by species compositions of both the mire and surrounding forests. The mire started to develop as a calcium-rich percolation fen with some species recently considered to be postglacial relicts (Meesia triquetra, Betula nana), shifted into ombrotrophy around 7450 cal yr BP by autogenic succession and changed into a pauperised, nutrient-enriched spruce woodland due to modern forestry activities. We therefore concluded that its recent vegetation is not a product of natural processes. From a methodological viewpoint we demonstrated how using multiple biotic proxies and extensive training sets in transfer functions may overcome taphonomic problems.     

Timing of the Northern Prince Gustav Ice Stream retreat and the deglaciation of northern James Ross Island,Antarctic Peninsula during the last glacial–interglacial transition

The Northern Prince Gustav Ice Stream located in Prince Gustav Channel, drained the northeastern portion of the Antarctic Peninsula Ice Sheet during the last glacial maximum. Here we present a chronology of its retreat based on in situ produced cosmogenic ¹⁰Be from erratic boulders at Cape Lachman, northern James Ross Island. Schmidt hammer testing was adopted to assess the weathering state of erratic boulders in order to better interpret excess cosmogenic ¹⁰Be from cumulative periods of pre-exposure or earlier release from the glacier. The weighted mean exposure age of five boulders based on Schmidt hammer data is 12.9 ± 1.2 ka representing the beginning of the deglaciation of lower-lying areas (< 60 m a.s.l.) of the northern James Ross Island, when Northern Prince Gustav Ice Stream split from the remaining James Ross Island ice cover. This age represents the minimum age of the transition from grounded ice stream to floating ice shelf in the middle continental shelf areas of the northern Prince Gustav Channel. The remaining ice cover located at higher elevations of northern James Ross Island retreated during the early Holocene due to gradual decay of terrestrial ice and increase of equilibrium line altitude. Schmidt hammer R-values are inversely correlated with ¹⁰Be exposure ages and could be used as a proxy for exposure history of individual granite boulders in this region and favour the hypothesis of earlier release of boulders with excessive ¹⁰Be concentrations from glacier directly at this site. These data provide evidences for an earlier deglaciation of northern James Ross Island when compared with other recently presented cosmogenic nuclide based deglaciation chronologies, but this timing coincides with rapid increase of atmospheric temperature in this marginal part of Antarctica.     

能源转型背景下不可忽视的新能源:天然氢

世界能源结构正面临着从化石能源向非化石能源过渡的第3次转变,氢气作为易燃且燃烧时不产生污染的清洁能源,将在其中起到重要作用.目前,氢的工业生产主要通过煤、天然气等化石燃料以及电解水制取,对天然氢的勘探开发刚刚起步,仅在非洲马里开采出天然氢.但是,天然氢已在世界各地被陆续发现,据相关文献报道:天然氢可能来源于深源、水岩反...