《中国公路交通实用图集》的设计和编制     

张冬梅 《测绘通报》2009,(8)

介绍《中国公路交通实用图集》的设计、编制特色,概述生成该图集的技术路线,并着重对图集编制过程中运用到的地图数据库技术、GIS和DTP等技术进行阐述。  相似文献   

An orthogonal experimental study of phytolith size of Phragmites communis in northeast China          下载免费PDF全文

Lidan Liu  Dongmei Jie  Hongyan Liu  Zhuo Gao  Guizai Gao  Nannan Li  Jixun Guo  Zhihe Qiao 《Boreas: An International Journal of Quaternary Research》2016,45(1):122-132

Based on the widespread distribution and abundant phytoliths produced by Phragmites communis, phytoliths of P. communis in northeast China were investigated to identify the primary influencing factors on phytolith size using an orthogonal experimental method. Temperature and precipitation were found to be the prominent factors influencing the sizes of short‐cell phytoliths including the saddle and the rondel morphotypes, whereas there were no obvious variations in the width‐to‐length ratios of short‐cell phytoliths in response to environmental factors. These results indicate that short‐cell phytoliths are genetically stable, confirming that they can be used for the classification of grasses. Moreover, precipitation was the main factor influencing the sizes of the lanceolate phytoliths and silicified stomata, and their width‐to‐length ratios changed significantly in response to precipitation and habitat differences. These findings reveal that lanceolate and silicified stomata phytoliths are sensitive to environmental changes, indicating their usefulness for palaeoenvironment reconstruction. Moreover, variations in their width‐to‐length ratios and their sizes may provide some information for plant classification, even at species level. Finally, the results of a principal component analysis of the sizes of P. communis phytoliths further verify the reliability of the orthogonal experiment results, in that temperature and precipitation were the prominent factors influencing the size of all P. communis phytoliths except for the length of saddle and width of the saddle morphotypes. This research into the primary environmental significance of the sizes of P. communis phytoliths may contribute to improving the precision of plant classification and the model for quantitative reconstruction of the palaeoenvironment to aid in reconstructions of palaeovegetation and palaeoclimate.  相似文献   

Tracing contributions to hydro‐isotopic differences between two adjacent lakes in the southern Tibetan Plateau          下载免费PDF全文

Xiaonan Shi  Fan Zhang  Lide Tian  Daniel R. Joswiak  Chen Zeng  Dongmei Qu 《水文研究》2014,28(22):5503-5512

Hydrological processes of lakes in the Tibetan Plateau are an important indicator of climate change. Due to the high elevation, inaccessibility and limited availability of historical observations, water budget evaluation of typical lake basins has been inadequate. In this study, stable isotopes are used to trace the multiple water sources contributing to two adjacent lakes on the north slope of the Himalayas, Gongmo‐tso and Drem‐tso. The two lakes have nearly the same elevation, lake area and climatic condition. However, the isotopic composition of the two lakes presents significant differences. Qualitative observations attribute the differences to hydrological discrepancies: Gongmo‐tso is a through‐flow lake, whereas Drem‐tso is a terminal lake. Quantitative analyses, including water and isotope mass balance modelling, clarify the fluxes and isotopic compositions among the various hydrological elements. The isotopic composition of input water, calculated as the summation of rainfall and upstream runoff, is estimated using the local meteoric water line (LMWL) combined with the time series of lake water isotope values. The isotopic composition of evaporation is calculated with a linear resistance model using local meteorological data. The results show that Drem‐tso is a closed lake in a hydrological steady state with relatively more enriched lake water isotope values resulting mainly from evaporation. In contrast, through‐flow accounts for more than 88% of the water input into Gongmo‐tso. The large amount of upstream runoff with lower isotopic composition and enrichment due to evaporation are the major contributions to the observed lake water isotope values. Isotopic modelling of the two neighbouring lakes is effective for isotopic and hydrological research in this region with limited in situ observations. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

基于卫星遥感的新疆地表太阳总辐射估算     

彭冬梅  陈鹏翔  张旭 《干旱气象》2019,37(2):322-330

为了实现地表太阳总辐射合理的精细化模拟,本文尝试将天文辐射分布式理论模型和总辐射气候学经验模型相结合,引入重采样后的FY-2G卫星遥感总云量资料,建立了基于卫星遥感数据的地表太阳总辐射估算模型,并以气象站点稀疏的新疆为例,完成年、季地表太阳总辐射的精细化空间模拟,同时对模拟结果进行分析和检验。结果表明:(1)新疆区域年天文辐射量由南向北递减,大致以天山为界,天山以南区域的年天文辐射量高于10 000 MJ·m^-2,天山以北低于9750 MJ·m^-2,三大山脉对天文辐射的影响非常明显;(2)基于条带状重采样后的FY-2G总云量建立的日照百分率模型,其模拟的新疆区域平均绝对误差14.4%,且空间分布更加客观;(3)新疆"单站单月式"地表太阳总辐射气候学估算模型中,相关系数在夏半年较高,冬半年略有下降,且a、b系数的互补关系较为稳定;(4)从地表太阳总辐射检验结果来看,全区地表太阳总辐射的均方根误差年平均3.08 MJ·m^-2,模拟结果夏半年好于冬半年,南疆好于北疆,其中乌鲁木齐误差最大;(5)新疆年地表太阳总辐射整体表现为由西北向东南逐渐增加的空间分布,南疆盆地的总辐射量高于北疆盆地,天山山区西部为低值中心,而春、夏季总辐射由西向东呈经向分布,秋、冬季则呈纬向分布。  相似文献   

Formation Age and Evolution Time Span of the Koktokay No. 3 Pegmatite,Altai, NW China: Evidence from U–Pb Zircon and 40Ar–39Ar Muscovite Ages          下载免费PDF全文

Qifeng Zhou  Kezhang Qin  Dongmei Tang  Ye Tian  Mingjian Cao  Chunlong Wang 《Resource Geology》2015,65(3):210-231

The Koktokay No. 3 pegmatite is the largest Li–Be–Nb–Ta–Cs pegmatitic rare‐metal deposit of the Chinese Altai orogenic belt, and is famous for its concentric ring zonation pattern (nine internal zones). However, the formation age and evolution time span have been controversial. Here, we present the results of LA‐ICP–MS zircon U–Pb dating and muscovite ⁴⁰Ar–³⁹Ar dating. Four groups of zircon U–Pb ages (～210 Ma, ～193–198 Ma, ～186–187 Ma and ～172 Ma) for Zones II, V, VI, VII, and VIII, and a weighed mean ²⁰⁶Pb/²³⁸U age of 965 ± 11 Ma for Zone IV are identified. Also, Zones II, IV, and VI have muscovite ⁴⁰Ar–³⁹Ar plateau ages of 179.7 ± 1.1 Ma, 182.1 ± 1.0 Ma, and 181.8 ± 1.1 Ma, respectively. Considering previous U–Pb age studies (Zones I, V, and VII), the ages of emplacement, Li mineralization peak, hydrothermal stage of the No. 3 pegmatite are in ranges of 193–198 Ma, 184–187 Ma and 172–175 Ma, with weighted mean ²⁰⁶Pb–²³⁸U ages of 194.8 ± 2.3 Ma, 186.6 ± 1.3 Ma and 173.1 ± 3.9 Ma, respectively. The No. 3 pegmatite formed in the early Jurassic. The results of xenocrysts suggest that there is another pegmatite forming event of around 210 Ma in the mining district and the old zircon U–Pb ages imply that Neoproterozoic crustal rocks pertain to sources of the No. 3 pegmatite. Including the previous muscovite ⁴⁰Ar–³⁹Ar age studies (Zones I and V), a cooling age range of 177–182 Ma is considered as the time of hydrothermal stage and end of formation. The evolution process of the No. 3 pegmatite lasted 16 Ma. Therein, the magmatic stage continued for 9–11 Myr and the magmatic–hydrothermal transition and hydrothermal stages were sustained at 5–7 Ma. These time spans are long because of huge scale, cupola shape, large formation depth, and complex internal zoning patterns and formation processes. Considering some pegmatite dikes in the Chinese Altai, there is an early Jurassic pegmatite forming event.  相似文献   

基于雷达回波的自动站小时异常强降水量质控算法研究          下载免费PDF全文

徐全倩  李志鹏  周晓香  刘冬梅  赖亮 《气象与减灾研究》2021,44(2):121-126

目前江西省自动气象站数据质控软件仅依靠降水数据本身的时间、空间相关性进行质控,存在部分异常强降水量漏识别问题.文中利用江西省气象信息中心提供的雷达回波资料和国家站降水观测资料,设计了雷达综合反射率质控参数,并对逐6 min累计降水量和雷达综合反射率值进行统计分析,建立了江西本地化的不同等级6 min累计降水量对应的雷达综合反射率最低阈值质控方案.该方案能较好地检测出江西省自动站降水资料中与雷达回波强度不匹配的小时异常强降水数据.目前该方案已应用于江西省自动站逐小时降水量数据实时自动质控业务中,有效提高了自动站异常强降水的质控效果.  相似文献   

江西地区冬半年极端低温事件主模态及环流特征          下载免费PDF全文

马锋敏  刘冬梅 《气象与减灾研究》2023,46(1):1-8

基于1961—2022年江西日最低气温观测资料和NCEP/NCAR再分析资料,首先极端低温阈值,分析极端低温事件发生频次的分布特征;再利用经验正交函数(EOF)获得极端低温事件发生频次的主模态,分析相应的关键环流系统特征。结果表明：江西省大部分地区冬半年极端低温阈值在0℃以下,南北分布差异较明显。极端低温事件发生频次在空间上具有很好的一致性,在1985年前后由偏多转为偏少的年代际振荡。极端低温发生频次主模态的变化受冬季风系统关键成员的影响显著,东亚冬季风偏强、西伯利亚高压偏强、东亚大槽加深、副热带西风急流偏强都利于江西地区出现极端低温事件。  相似文献   

应用GPS水准与重力数据联合解算大地水准面   总被引：1，自引：0，他引：1  

郭东美  许厚泽 《武汉大学学报(信息科学版)》2011,(5):621-624

GPS水准大地水准面与重力大地水准面之差不仅由基准不同引起,而且也包含重力与GPS水准观测值的误差。建立了这两个水准面之差与基准转换参数、重力和GPS水准观测值的残差之间的关系,并基于最小二乘准则解算了基准转换参数和重力与GPS水准观测值的残差,即计算转换参数及重力与GPS观测值的改正。尤其当GPS水准精度远高于重力水准面时,联合解算模型可固定GPS水准大地水准面,只对重力观测值进行改正。  相似文献   

地磁整10′位近零观测方法的适用性研究     

邓娜  杨冬梅  何宇飞  杨艳芳 《地震地磁观测与研究》2011,32(2):31-33

针对"十五"地磁台网引进的秒级MINGEO DIM磁通门经纬仪的性能特点,结合台站地磁场背景值及仪器格值精度,对地磁整10′位近零观测方法的注意事项和约束条件进行系统分析,指出将MINGEO DIM磁通门经纬仪格值标定精度控制在不大于2‰的必要性及重要意义.  相似文献   

天津市中尺度数值预报业务系统的设计与实现     

袁卫华  赵玉娟  孟冬梅  武国良 《气象科技》2011,39(6):828-833

为适应省级中尺度数值预报业务的需要,设计实现了天津市中尺度数值预报业务系统。该系统由高性能计算机系统、中尺度数值预报模式以及业务运行流程组成的,其设计与实现涉及到高性能计算机系统的建设、中尺度数值预报模式的业务数据流转以及系统运行监控流程的设计等多个方面。高性能计算机系统的建设包括系统选型、功能设计和安装调试等部分,中尺度数值预报模式的业务数据流转以及系统运行监控流程的设计是整个系统业务化的关键。天津市中尺度数值预报业务系统通过工程建设和技术开发完成了奥运期间的气象预报服务任务,已投入业务化运行。  相似文献