National height datum,the Gauss–Listing geoid level value w0 and its time variation 0 (Baltic Sea Level Project: epochs 1990.8, 1993.8, 1997.4)     

A. Ardalan  E. Grafarend  J. Kakkuri 《Journal of Geodesy》2002,76(1):1-28

 A methodology for precise determination of the fundamental geodetic parameter w ₀, the potential value of the Gauss–Listing geoid, as well as its time derivative ₀, is presented. The method is based on: (1) ellipsoidal harmonic expansion of the external gravitational field of the Earth to degree/order 360/360 (130 321 coefficients; http://www.uni-stuttgard.de/gi/research/ index.html projects) with respect to the International Reference Ellipsoid WGD2000, at the GPS positioned stations; and (2) ellipsoidal free-air gravity reduction of degree/order 360/360, based on orthometric heights of the GPS-positioned stations. The method has been numerically tested for the data of three GPS campaigns of the Baltic Sea Level project (epochs 1990.8,1993.4 and 1997.4). New w ₀ and ₀ values (w ₀=62 636 855.75 ± 0.21 m²/s², ₀=−0.0099±0.00079 m²/s² per year, w ₀/&γmacr;=6 379 781.502 m,₀/&γmacr;=1.0 mm/year, and &γmacr;= −9.81802523 m²/s²) for the test region (Baltic Sea) were obtained. As by-products of the main study, the following were also determined: (1) the high-resolution sea surface topography map for the Baltic Sea; (2) the most accurate regional geoid amongst four different regional Gauss–Listing geoids currently proposed for the Baltic Sea; and (3) the difference between the national height datums of countries around the Baltic Sea. Received: 14 August 2000 / Accepted: 19 June 2001  相似文献   

Relationship between land cover and monsoon interannual variations in east Asia   总被引：5，自引：0，他引：5  

Xiang Bao  Liu Ji-yuan 《地理学报(英文版)》2002,12(1):42-48

Asian monsoon have multiple forms of variations such as seasonal variation, intra-seasonal variation, interannual variation, etc. The interannual variations have not only yearly variations but also variations among several years. In general, the yearly variations are described with winter temperature and summer precipitation, and the variations among several years are reflected by circulation of ENSO events. In this study, at first, we analyze the relationship between land cover and interannual monsoon variations represented by precipitation changes using Singular Value Decomposition method based on the time series precipitation data and 8km NOAA AVHRR NDVI data covering 1982 to 1993 in east Asia. Furthermore, after confirmation and reclassification of ENSO events which are recognized as the strong signal of several year monsoon variation, using the same time series NDVI data during 1982 to 1993 in east Asia, we make a Principle Component Analysis and analyzed the correlation of the 7th component eigenvectors and Southern Oscillation Index (SOI) that indicates the characteristic of ENSO events, and summed up the temporal-spatial distribution features of east Asian land cover’s inter-annual variations that are being driven by changes of ENSO events.  相似文献   

东亚土地覆盖动态与季风气侯年际变化的关系     

香宝  刘纪远 《地理学报》2002,12(1):42-48

以东亚地区 １９８２～１９８９年时间序列降水资料及 ＡＶＨＲＲ ８ ｋｍ ＮＤＶＩ数据为基本数据源，应用地理信息系统技术，分别研究了东亚地区夏季（５－９月）降水及土地覆盖的年际变化，并揭示了研究时间段内各自的变化规律。进一步用奇异值分解（ＳＶＤ）模型方法分析了以降水变化为表征的东亚地区气候年际变化与土地覆盖年际变化之间的关系。  相似文献   

全球生产网络(GPN)的理论问题和中国实践启示     

陈蕊  刘逸 《地理研究》2021,40(12):3259-3271

全球生产网络理论（GPN）是关系经济地理学派的核心理论成果,但当前国内外研究对其发展脉络和理论内涵的认识存在模糊之处,在应用方面也存在一些误区。因此,本文从GPN与全球价值链（GVC）理论互动的视角出发,回顾GVC和GPN的重要发展阶段及对彼此的影响,针对常见的对GPN理解和应用的误区展开解释与辨析,主要得到3个结论。第一,GPN理论的研究目的已从解释“价值生产”凝练为解释“区域发展的不均衡”,更贴近经济地理学的基本研究范式。第二,GPN与GVC正在从分歧走向融合,共同致力于捕捉与解释全球化动态。第三,并非所有跨国公司研究或生产网络研究都属于GPN研究,GPN专指研究跨国公司与主要相关者基于生产所形成的网络动态,不适用于以国家为单位的研究,也不着力于揭示企业内部经营管理动态。本文继而指出中国经验既需要GPN理论加以探析、也有助于丰富GPN理论,精准理解GPN尤其对中国当前推行双循环战略有重要应用价值。本文强调,GPN作为中观理论框架,有效解释了全球经济中区域发展的多尺度动态,在全球化出现逆流的新形势下,对中国全球化实践,特别是国际国内双循环发展有着鲜明的研究意义。  相似文献   

依舒断裂带北段尾波Q值特征研究     

李继业  孙鹏宇  武晓军  张彦吉  任建辉  秦丽岩  孙强 《中国地震》2018,34(3):545-550

研究表明,地震波穿过构造活动相对稳定地区时,能量衰减不明显且具有高Q值;而穿过构造活动地区时,能量会发生强烈衰减且具有低Q值。本文利用Sato模型对依舒断裂带北段萝北-通河地区15个数字化地震台站记录到的266条M_L≥2.0地震尾波Q_c值进行了分析和研究,发现黑龙江萝北、通河附近地区Q_c值具有明显的复杂性和差异性,且萝北地区Q_c值远低于通河地区Q_c值,其原因一方面与区域构造活动有关,另一方面与区域地壳构造复杂、地下介质破碎、区域应力不断变化有关。本文还讨论了萝北、通河附近地区Q值随着频率变化的关系及Q_0值空间分布特征,有效地分析了该区域介质状态的变化过程,对萝北地区地震活动性的研究和预测有指导意义。  相似文献   

长岛震群b值随深度变化特征     

申金超  李士成  张斌 《地震》2019,39(2):28-36

利用双差定位方法对2017年2月~2018年5月长岛震群进行重定位, 根据重定位结果计算长岛震群地震集中活动区域b值在深度上的变化分布。 结果显示: 长岛震群重定位的结果主要表现为北、 南两个地震活动区域。 北部地震活动区域的地震数量多, 时间跨度长; 南部地震活动区域的地震数量较少, 形成时间较晚, 震源深度主要集中在地壳深度4~25 km之间; 长岛震群北、 南两个地震活动区域的b值总体上均随深度增大而减小, 在8.5 km深度左右均存在转折上升的情况。 长岛震群b值的深度变化特征表明, 其应力主要受围岩静压力影响, 受断裂活动影响较小。  相似文献   

试论完善多种用海功能的海域使用权抵押制度的路径          下载免费PDF全文

董翰霖 《海洋开发与管理》2019,36(1):20-22,69

海域使用权抵押作为新兴的融资方式,得到普遍的认可,但是因相关法律未明确以怎样的方式对海域使用权价值的评估,故其在实践中遇到适用的阻碍,文章主要从农渔业用海和工矿交通用海权两个方面进行论述,阐释了对海域使用权价值的评估体系,也就是说对渔业适用三方联保贷款,而工矿交通则适用设立专门的担保机构以此来解决海洋功能分类定制,便于向金融机构以海域使用权获得相应的贷款,促进经济发展,为改革开放40年经济持续发展献出绵薄之力。  相似文献   

乌鲁木齐市酸雨特征及变化趋势   总被引：2，自引：0，他引：2  

刘新春  何清  艾力·买买提明  梁云  南庆红  LIU Xin-chun  HE Qing  Aili·MAMTIMIN  LIANG Yun  NAN Qing-hong 《沙漠与绿洲气象(新疆气象)》2007,1(5):10-14

通过对乌鲁木齐市1991—2007年降水pH值、K值(电导率)以及相关的天气气候资料的处理,分析了酸雨特征和变化趋势。结果表明:pH平均值有逐年降低的趋势;从2000年开始K平均值呈下降趋势;降水pH平均值和K平均值具有明显的季节变化;供暖对pH平均值和K平均值造成很大的影响,是形成酸雨的重要因素之一。  相似文献   

Temperature Extremes from Canadian Regional Climate Model (CRCM) Climate Change Projections     

Barbara Casati  Ramon de Elía 《大气与海洋》2014,52(3):191-210

Future climate projections of extreme events can help forewarn society of high-impact events and allow the development of better adaptation strategies. In this study a non-stationary model for Generalized Extreme Value (GEV) distributions is used to analyze the trend in extreme temperatures in the context of a changing climate and compare it with the trend in average temperatures.

The analysis is performed using the climate projections of the Canadian Regional Climate Model (CRCM), under an IPCC SRES A2 greenhouse gas emissions scenario, over North America. Annual extremes in daily minimum and maximum temperatures are analyzed. Significant positive trends for the location parameter of the GEV distribution are found, indicating an expected increase in extreme temperature values. The scale parameter of the GEV distribution, on the other hand, reveals a decrease in the variability of temperature extremes in some continental regions. Trends in the annual minimum and maximum temperatures are compared with trends in average winter and summer temperatures, respectively. In some regions, extreme temperatures exhibit a significantly larger increase than the seasonal average temperatures.

The CRCM projections are compared with those of its driving model and framed in the context of the Coupled Model Intercomparison Project, phase 3 (CMIP3) Global Climate Model projections. This enables us to establish the CRCM position within the CMIP3 climate projection uncertainty range. The CRCM is validated against the HadEX2 dataset in order to assess the CRCM representation of temperature extremes in the present climate. The validation is also framed in the context of CMIP3 validation results. The CRCM cold extremes validate better and are closer to the driving model and CMIP3 projections than the hot extremes.  相似文献   

What determines perceived value of seasonal climate forecasts? A theoretical analysis     

Antony Millner  Richard Washington   《Global Environmental Change》2011,21(1):209-218

Seasonal forecasts have potential value as tools for the management of risks due to inter-annual climate variability and iterative adaptation to climate change. Despite their potential, forecasts are not widely used, in part due to poor performance and lack of relevance to specific users’ decision problems, and in part due to a variety of economic and behavioural factors. In this paper a theoretical model of perceived forecast value is proposed and applied to a stylized portfolio-type decision problem with wide applicability to actual forecast users, with a view to obtaining a more complete picture of the determinants of perceived value. The effects of user wealth, risk aversion, and perceived forecast trustworthiness, and presentational parameters, such as the position of forecast parameter categories, and the size of probability categories, on perceived value is investigated. Analysis of the model provides several strong qualitative predictions of how perceived forecast value depends on these factors. These predictions may be used to generate empirical hypotheses which offer the chance of evaluating the model's assumptions, and suggest several means of improving understanding of perceived value based on qualitative features of the results.  相似文献