横断山脉地区大气环流演变特征分析

应用Lamb-Jenkinson大气环流分型方法对横断山脉地区的8个经度×10个纬度范围内1948-2012年逐日平均的海平面气压场进行环流分型,由日平均海平面气压场算出6个环流指数（u、v、V、ξu、ξv、ξ）,并由此划分出27种不同的环流型。分型结果表明：横断山脉地区主要环流分型为E型、NE型、SE型、N型和C型,其频率分别为：21.4%、14.6%、13.7%、9.8%和9.5%;E和NE型环流频率逐渐增加,C型环流型频率逐渐减少。春季横断山脉地区主导环流比较繁琐;NE、N型为夏季的主要环流型,但E型环流在夏季的频率也相当大;秋季和冬季横断山脉地区的主导环流型都为E型和SE型。夏季主导环流型持续时间较长,冬季也是主导环流持续的时间较长,个别年份主导环流型持续时间超过了一个月,这主要与横断山脉地区复杂的地形有联系。     

The Impact of Mid- and High-Latitude Rossby Wave Activities on the Medium-Range Evolution of the EAP Pattern During the Pre-Rainy Period of South China

Based on the NCEP DOE AMIP II daily reanalysis data (1979{2005), the evolution of the East Asia/Pacific(EAP) teleconnection pattern during the pre-rainy period of South China is studied on the medium-range time scale. It is found that positive and negative EAP patterns share a similar generation process. In the middle and upper troposphere, Rossby wave packets emanating from the northeast Atlantic or Europe propagate toward East Asia along the Eurasian continent waveguide and finally give rise to the three anomaly centers of the EAP pattern over East Asia. Among the three anomaly centers, the western Pacific subtropical center appears the latest. Rossby wave packets propagate from the high latitude anomaly center toward the mid-latitude and the subtropical ones. The enhancement and maintenance of the subtropical anomaly center is closely associated with the subtropical jet waveguide and the incoming Rossby wave packets from the upstream. In the lower troposphere, Rossby wave packets emanate from the subtropical Asia toward East Asia. Positive and negative EAP patterns could not be regarded as "mirrors" to each other with simply re- versed phase. For the positive pattern, the positive height anomaly center around the Scandinavia Peninsula keeps its strength and position during the mature period, and the Rossby wave packets thus propagate persistently toward East Asia, facilitating a longer mature time of the positive pattern. As for the formation of the negative EAP pattern, however, the incoming Rossby wave energy from the upstream contributes to both the enhancement and southeastward movement of the negative anomaly belt from the Yenisei River to the Bering Strait and the positive anomaly center around Mongolia. At the peak time, the two anomlous circulations are evolved into the Northeast Asia and the mid-latitude anomaly centers of the negative pattern, respectively. The energy dispersion of Rossby wave packets is relatively fast due to the predominant zonal circulation in the extratropics, causing a shorter mature period of the negative pattern. During the pre-rainy period of South China, the prevalence of the EAP pattern signiˉcantly affects the rainfall over the region south of the Yangtze River. The positive (negative) EAP pattern tends to causepositive (negative) precipitation anomalies in that region. This is di?erent from the earlier research findingsbased on monthly mean data.     

上市公司与客户联系视角下的中国城际网络结构时空演化研究

企业间的联系是城市联系的重要组成部分,加强对基于企业间联系的城市功能网络分析对丰富城市网络理论研究具有重要意义。采用2010—2020年上市公司与其前五大客户间的贸易关系数据构建了中国城市网络,基于企业间的贸易联系视角分析城市网络时空演变特征。研究表明：(1) 2010—2020年间城市网络规模呈现先升后降的特征,整体网络密度较低,位于0.014～0.018之间;网络重心呈现“S”形空间轨迹变化和整体向南移动的趋势,网络总体空间结构由沿海向“T”形结构转变;(2)网络流量集中于少数节点城市,资金进出量前20城市总额占资金总流量的71.9%,北京、上海是网络的绝对核心,杭州、武汉、深圳、广州等省会或副省级城市承担着区域中心的功能,佛山、齐齐哈尔、南通等制造业发达城市是重要节点;(3)五大城市群中珠江三角洲网络密度最高,位于0.324～0.334之间,长江三角洲贸易总流量最高,为783.5亿元,长江中游城市群和成渝城市群网络发育相对滞后;(4)新冠疫情对整体网络的贸易流量和网络结构产生了明显影响,网络社团进一步分化重组,广州—深圳社团明显增强,上海社团明显减弱。研究结果对推动国内大循环和统...     

Downward migration of seismic activity prior to some great shallow earthquakes in Japanese subduction zones—a possible intermediateterm precursor

Before the 1944 Tonankai earthquake along the Nankai Trough, seismic activity increased in the shallow depths, and then the activity gradually migrated downwards. When it reached its limit (a depth of approximatelty 70 km), the main shock occurred. Several deep earthquakes, including one ofM5.3, occurred several months prior to the Tonankai earthquake. A similar downward migration pattern also can be recognized regarding the 1952 Tokachi-oki earthquake. In this case the deepest earthquakes reached about 400 km. This may be one of the intermediate-term precursory phenomena of great thrusttype earthquakes in subduction zones. Recent observations in the Tokai district along the Suruga Trough, where a large earthquake is expected to occur in the future, suggest a similar downward migration pattern in the land area.     

一种基于特征信息的车牌识别方法

根据中国车辆牌照本身的现有特征信息,提出一种车牌识别方法.采用全局动态阈值法进行二值化处理图像,牌照定位算法简单迅速,字符分割参考垂直投影间隔和字符的纵横比.实验结果表明,这种方法具有良好的环境适应性和鲁棒性.     

环莫干山民宿的时空分布特征与成因

民宿是中国乡村振兴和旅游转型升级过程中涌现出的新兴业态和空间利用方式,但学术关注滞后。环莫干山地区是目前中国最典型的民宿发展集聚区之一。本研究通过官方统计资料和实地调研获取环莫干山民宿空间发展数据,构建了ArcGIS和地理探测器结合的民宿空间过程分析方法,基于目的地的微观尺度系统地探讨环莫干山民宿时空分布特征和成因。研究发现：① 2011—2017年环莫干山民宿呈现出逐年增长的态势,空间分布范围不断扩大,空间发展方向出现较大变化,逐渐趋向镇域均衡性发展。目前已经在莫干山风景区毗邻村域形成以“后坞-仙潭-燎原-劳岭-兰树坑”为中心的环莫干山面状核心集聚区和边缘村域多点集聚的民宿空间发展结构。不同档次民宿的时空发展趋势具有一定差异。② 环莫干山民宿的空间过程由集聚到强烈集聚,不同档次民宿的集聚程度均呈现出快速提升的趋势。空间发展过程中早期民宿集聚点扩散效应显著。空间集聚过程与地形地势、核心风景区、交通干线和居民点密切相关。③ 风景景观、发展基础、社会因素和区位因素是环莫干山民宿景观格局异质性的重要决定因素维度,但不同等级民宿的空间决定因素维度和指标差异性显著,两因素维度交互作用对于民宿的空间影响力更为显著。研究对于丰富接待业空间选址的类型研究,总结中国典型民宿集聚区空间发展模式具有重要理论意义,同时对于民宿产业选址和民宿集聚区规划实践具有一定现实意义。     

江苏盛夏两次局地特大暴雨过程对比分析

本文利用Micaps资料、江苏自动气象站数据、常州多普勒雷达观测和NCEP全球分析场,从降水实况、环流背景、雷达回波特征、动力和热力条件等方面,对2009年8月2日和2011年7月13日两次江苏盛夏局地特大暴雨过程进行了分析和比较。结果表明:大尺度鞍型场背景下副热带高压和大陆高压的同时增强使得降水系统更集中、对流发展更旺盛,降水中心在低空切变的南侧、地面辐合的北侧、水汽在大陆东部输送的顶点。而副热带高压相对较弱的情形下,有利于热带低值系统外围偏东风场的持续水汽输送,对流发展较弱,但持续时间更长;配合低层深厚的中尺度触发系统,使得局地降水强度更有爆发力,降水中心靠近水汽在大陆东部的输送起点。     

利用方式对东北黑土粘土矿物组成的影响

土地利用方式是影响土壤可持续利用的重要因素。粘土矿物是土壤重要的活泼物质,会受利用方式的影响而发生改变。为了揭示利用方式对土壤粘土矿物的影响,对不同利用方式下的东北黑土进行土壤理化特性及粘粒XRD分析。结果表明:荒地、旱田(大豆)、旱田(玉米)、水田利用的土壤矿物颗粒的风化依次增强,伊利石的含量和结晶度也依次降低。经水田利用后的黑土,粘土矿物的演变过程为:云母→伊利石→蛭石和绿泥石。定量结果表明黑土水田利用会出现蛭石绿泥石化现象。综合说明旱田利用会使土壤结构破坏以及水土流失加剧,而水田利用则能较好的协调土壤理化性质,可较大程度的改良土壤。     

Evolution of 3D tectonic stress field and fault movement in North China

IntroductionThe research on stress field interior the Earth is an either relative old or young branch of geoscience. Early in the 20th century, in order to learn the state of inner stress field, a few scholars had used simple ideal model to analyze big scale tectonic conformations and activities according to tide, gravity, rotation and inner thermal materials. So far, lots of problems on the state of the Earth stress field have not been solved completely yet. The origin of stress field, the d…     

关于后数字城市建设时代的项目建设建议

从数字城市建设的特点、特征入手,阐述了几种建设模式、主要建设内容、组织实施,按照公共产品与区域经济有关理论,实证了城乡统筹建设模式对于区域信息化建设的传导与辐射作用,并从区域经济发展、政府职能转变、消费市场培育等角度给出了进一步的对策与建议。