图们江下游跨国界经济开发区的空间极化问题研究   总被引：1，自引：0，他引：1  

陈长春 《世界地理研究》1995,(1)

本文以东北亚区域经济合作为主要背景，以区域极化发展理论为指导，对图们江下游跨国界经济开发区这一发展极核的概念进行说明，提出了该新型经济开发区赖以产生和发展的背景条件与区位条件，并对其极核的功能效应作了初步预测与展望。以对国内外积极参与图们江下游地区的合作开发提供参考依据。  相似文献   

The Late Carboniferous to Early Triassic geodynamic evolution of Variscan Europe in the light of magnetic overprints in Early Permian rhyolites from the northern Vosges (France) and central Black Forest (Germany)     

J. B. Edel  J. L. Schneider 《Geophysical Journal International》1995,122(3):858-876

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电离层极风的EISCAT-VHF雷达观测   总被引：2，自引：0，他引：2       下载免费PDF全文

吴健 Blanc  M 《地球物理学报》1993,36(1):9-17

极风现象从理论上提出已20多年了,实验上一直没有充分地证实这种现象的存在,以及它的形成区域位于高纬顶部电离层中.我们利用欧洲非相干散射协会（EISCAT）的VHF雷达（在挪威Tromsφ）,对H⁺离子极风进行了首次实验研究,结果表明,实验期间观测到H⁺离子在顶部电离层中的运动速度始终向上,且随高度的增加而增大,从而证实在高纬顶部电离层中确实存在着一个永久向上的H⁺离子流,即H⁺离子极风,其速度在1000km 高度上达到1km/s,其通量在此高度上接近于饱和,达到10¹²m^s（-1）,而温度小于0.26eV.在我们的探测高度上仍未发展成超声速极风.  相似文献   

Dynamical Downscaling of the Arctic Climate with a Focus on Polar Cyclone Climatology     

Minghong Zhang  Zhenxia Long 《大气与海洋》2019,57(1):41-60

We present a dynamical downscaling of the Arctic climatology using a high-resolution implementation of the Polar Weather Research and Forecasting, version 3.6 (WRF3.6) model, with a focus on Arctic cyclone activity. The study period is 1979–2004 and the driving fields are data from the Hadley Centre Global Environmental Model, version 2, with an Earth System component (HadGEM2-ES) simulations. We show that the results from the Polar WRF model provide significantly improved simulations of the frequency, intensity, and size of cyclones compared with the HadGEM2-ES simulations. Polar WRF reproduces the intensity of winter cyclones found in ERA-Interim, the global atmospheric reanalysis produced by the European Centre for Medium-range Weather Forecasts (ECMWF), and suggests that the average minimum central pressure of the cyclones is about 10?hPa lower than that derived from HadGEM2-ES simulations. Although both models underestimate the frequency of summer Arctic cyclones, Polar WRF simulations suggest there are 10.5% more cyclones per month than do HadGEM2-ES results. Overall, the Polar WRF model captures more intense and smaller cyclones than are obtained in HadGEM2-ES results, in better agreement with the ERA-Interim reanalysis data. Our results also show that the improved simulations of Arctic synoptic weather systems contribute to better simulations of atmospheric surface fields. The Polar WRF model is better able to simulate both the spatial patterns and magnitudes of the ERA-Interim reanalysis data than HadGEM2-ES is; in particular, the latter overestimates the absorbed solar radiation in the Arctic basin by as much as 30?W?m^?2 and underestimates longwave radiation by about 10?W?m^?2 in summer. Our results suggest that the improved simulations of longwave and solar radiation are partly associated with a better simulation of cloud liquid water content in the Polar WRF model, which is linked to improvements in the simulation of cyclone frequency and intensity and the resulting transient eddy transports of heat and water vapour.  相似文献   

Role of Antarctic ice mass balance in present-day sea-level change     

C.K. Shum  Chung-yen Kuo  Jun-yi Guo 《Polar Science》2008,2(2):149-161

The Antarctic ice sheet is arguably the most critical in terms of future sea-level rise, primarily because it contains 70% of the world's fresh water. While there exists evidence of accelerated ice-sheet ablation during the past decade, the possibility that the ice sheets contributed little to 20th century sea-level rise could result in Antarctica becoming the largest contributor to sea-level rise during the 21st century. Here we review the findings of studies published following the 2007 Intergovernmental Panel for Climate Change (IPCC) study, focusing on the role of Antarctica in present-day (1992–2006) sea-level rise. We show that the choice of glacial isostatic adjustment (GIA) model significantly affects GRACE-estimated Antarctic mass loss, adding 0.25–0.45 mm/yr to the estimate of sea-level rise. The current estimate of Antarctica's contribution to sea-level rise has a wide range: from −0.12 to +0.52 mm/yr. The discrepancy between observed sea-level trend of 1.8 mm/yr and those estimated from various geophysical sources (2.10 ± 0.99 mm/yr) is 0.30 mm/yr. The role of Antarctica in sea-level rise might be better constrained by lengthening satellite observations, using long-term GPS data to discriminate subglacial vertical motion from ice mass balance, and detecting the sea-level signal due to elastic loading from the melting ice-sheets.  相似文献   

1979—2011年热带对流层顶高度线性趋势变化的因子贡献及其年际变率成因探讨   总被引：2，自引：0，他引：2  

郑彬  施春华 《热带气象学报》2015,31(3):300-309

利用美国国家环境预报中心/大气研究中心(NCEP/NCAR)再分析资料分析了近30年(1979—2011年)热带(0~360 °E,20 °S~20 °N)对流层顶高度变化,结果显示其高度有明显的线性上升趋势,近30年气压下降了3.5 hPa。其中对流、臭氧和对流层温度的贡献分别为13.3%、27.26%和57.31%。在去除线性趋势后,热带对流层顶气压表现出了显著的年际变率,主要周期峰值为18.2、28.6和40个月。其中臭氧和热带对流层温度都对18.2个月的周期有贡献,而臭氧和热带对流层温度18.2个月的周期很可能是由北半球的季风环流引起的;28.6个月的周期主要源于臭氧总量的准两年周期变化,而后者是由热带平流层低层纬向风场的准两年振荡引起的;热带对流层顶气压40个月的周期似乎源于ENSO循环引起的对流层温度变化。   相似文献   

Steady,barotropic wind and boundary-driven circulation on a polar plane     

Andrew J. Willmott  Maria V. Luneva 《地球物理与天体物理流体动力学》2015,109(3):216-233

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不同能谱沉降电子对极区电离层的影响   总被引：2，自引：1，他引：1       下载免费PDF全文

刘俊明  张北辰  刘瑞源  吴振森 《地球物理学报》2009,52(6):1429-1437

利用极区电离层自洽模型,考虑沉降电子引起的电离,计算了极区电离层的高度积分电导率和F层电子浓度,模拟了不同能谱分布的沉降电子对极区电离层的影响.研究发现不同能谱分布沉降电子对电离层电导率的影响不大,在能通量一定的情况下,平均能量是影响电导率大小的决定因素.而能谱对F层电子密度影响较大,随着平均能量的增加,能谱对电子浓度的影响越显著.在平均能量大于1 keV（甚至更低）时,修正的麦克斯韦分布谱能明显地增强F层电子浓度.  相似文献   

Seasonal baseline levels of physiological and biochemical parameters in polar cod (Boreogadus saida): Implications for environmental monitoring     

Jasmine Nahrgang  Lionel Camus  Jørgen S. Christiansen 《Marine pollution bulletin》2010,60(8):1336-5276

Seasonality of biomarker baseline levels were studied in polar cod (Boreogadus saida), caught in Kongsfjorden, Svalbard, in April, July, September and December, 2006-2007. Physiological parameters (condition factor, gonado- and hepato-somatic indexes, energy reserves, potential metabolic activity and antifreeze activity) in polar cod were used to interpret the seasonality of potential biomarkers. The highest levels of ethoxyresorufin-O-deethylase (EROD) activity occurred concomitantly with the highest potential metabolic activity in July due to e.g. intense feeding. During pre-spawning, EROD showed significant inhibition and gender differences. Hence, its potential use in environmental monitoring should imply gender differentiation at least during this period. Glutathione S-transferase and catalase activities were stable from April to September, but changed in December suggesting a link to low biological activity. Knowledge of the biomarker baseline levels and their seasonal trends in polar cod is essential for a trustworthy interpretation of forthcoming toxicity data and environmental monitoring in the Arctic.  相似文献   

TC2002极坐标测量系统在大型天线检测中的应用   总被引：1，自引：0，他引：1  

李广云  李宗春 《测绘工程》1999,8(4):35-39

单台全站仪极坐标测量系统应用于高精度的测量和安装工作中,必须采用特殊的作业手段和数据处理方法才能达到亚毫米的精度。文中提出了一种坐标转换方法,将其应用于大型多波束天线的安装检测过程中,实测结果表明该方法达到较好的效果。  相似文献