A 290-a record of atmospheric circulation over the North Pacific from a Mt.Logan ice core, Yukon Territory

Calibrations between sodium （Na^＋） concentrations from a Mt. Logan ice core and sea level pressure （SLP） series show that Na^＋ concentrations are closely correlated with the autumn-time （September-October-November） Aleutian low （AleuLow）. A deepening of the AleuLow strengthens the transport of sea-salt aerosols from the North Pacific to the Mt. Logan region. The Mt. Logan Na^＋ record is used to develop a 292 a （1688-1979） reconstruction of the AleuLow revealing a dramatic intensification of atmospheric circulation over the North Pacific region since the 20th century. Mean SLP of the AleuLow was about 1 hPa lower during the 20th century than during prior periods. The strongest deepening of the AleuLow appeared in the 1950s. Significant correlations are also found between the Mt. Logan AleuLow proxy series and the Pacific decadal oscillation （PDO） and Pacific circulation （PC） index during the 20th century. Evolutionary spectral analysis of the proxy record shows significant periodicities from 15 to 30 a consistent with PDO fluctuations and the bidecadal oscillation of North Pacific atmosphere-ocean circulation. A period of 11 a in the AleuLow record may be associated with the Schwabe 11-a cycle of sunspot activity. Additional longer ice core records from this region will aid in the efforts to further understand the climatic change over the North Pacific region.     

华南地区地震活动特征与台湾强震影响

以M_S5.5以上地震是否发生为标记, 划分华南地区的活跃和平静时段, 结果显示与华南地区2级以上地震频次的应力调制时间过程变化趋势有很好的一致性。 另外, 在活跃和平静时段华南地区的震级频次特点显著不同。 华南地区在中强震发生前有4级左右地震频繁活动和小震群频发的特点。 华南地区的中强震与云南地区7级地震的发生相关。 统计20世纪以来台湾强震与华南中强震的对应关系, 台湾西带6级强震后1年内华南中强震的对应率近0.5, 地区影响似有由东至西逐渐减弱的趋势。 台湾7级地震后2年内华南中强震的对应率只有0.3, 对应地区除台湾海峡、 福建和广东东部地震外, 也有几次对应广西和北部湾地区的地震, 与6级相比, 台湾7级强震影响范围大。     

2003年南极威德尔海至普里兹湾之间海冰分布研究

Ship-based sea ice observation data (concentrations,ice thickness,topography and overlying snow cover) were collected from Middle Weddell Sea to Prydz Bay,Antarctic during the period of 4 to 17 Jan 2003.Antarctic ice chart of first week of Jan 2003 was derived from National Ice Center (NIC).The compared analysis of sea ice concentrations and thickness distributions were conducted though in situ data and NIC chart.Results from sea ice concentration-analysis indicated the presence of large-scale open water between 2000 and 4100 km along transit route resulted from sea ice drifting.We describe the existence of mostly smooth first-year sea ice in study region ranged between 30 and 120 era.We also display the derived overlying snow coverage.Our results reveal the strong correspondence between ship-based observations and remotely sensed ice charts whatever in ice concentrations and ice thickness distributions.     

西北地区东部强震前地震活动演化特征

通过对1900年以来西北地区东部10次强震前不同时间尺度的地震分布特征以及演化过程的研究表明,西北地区东部强震前大多存在以下规律: 即在震中附近存在5级以上地震空缺的长期异常特征及中小地震活动水平升高的中短期异常特征。     

Topmodel模型在黑河干流出山径流模拟中的应用

概念性模型应用广泛,它由集总模式逐步发展为分布参数模式。文中介绍了一个基于土壤含水量和地形指数的概念性分布参数模型——Topmodel。该模型以小时为步长,对DEM分辨率的要求为50 m×50 m。为将模型应用到我国内陆河山区中大型流域,将模型的DEM分辨率拓宽到1 500 m×1 500 m,模拟过程也分别以日和月为步长。日径流模拟结果表明,在DEM分辨率较粗的情况下,模型有一个较长时间的土壤含水量调整期,之后模拟效果较好,尤其是枯水径流。月模型模拟效果较好,但模拟效果总体还是受DEM分辨率较粗的影响。     

ENSO循环与黄河上游径流的丰枯

1IntroductionScholarsoftheinternationalmeteorologicalandoceanographicalcirclesgenerallythinkElNinoeventhasoccurredwhenthepositivedeparturesofmeansea-surfacetemperature(SST)atEquatorialEastPacificOceanArea(lyingbetween0o-10oS,180o-90oW)occurcontinuallywith0.5oCexteedingthelong-rangemeanandcontinualperiodlastinghalfayear.TheyalsothinkLaNinaeventhasoccurredwhenthestrongernegativedeparturesoccur.SouthernOscillationoccurringsynchronouslywithElNinoindicatesitisaneventwithalternativeoccurrence…     

极地海冰的研究及其在气候变化中的作用

极地海冰作为全球气候系统的一个重要组成部分,通过影响大洋表面的辐射平衡、物质平衡、能量平衡以及大洋温、盐流的形成和循环而影响全球气候变化.从最初研究极地海冰的强度和承载力到目前海/冰/气相互作用全球气候耦合模型的建立,使海冰变化和全球气候变化紧密结合起来.这些研究领域主要有:海冰及其表层雪的物理特性和过程、海冰区域生态特征、海冰区与气候相关的反照率和物质平衡研究以及海冰气候耦合模型等大的领域.模拟显示,21世纪因为全球变暖,南北极海冰都将减少.海冰和全球气候系统其它要素之间的相互作用问题、极地海冰的厚度季节性区域性分布问题、极地海冰边界及范围变化趋势问题、生消关键过程及其影响因素问题、冰间湖的作用以及海气相互作用等将是未来重要的研究方向.     

基于PSO-SVM的边坡稳定性组合预测方法研究

为利用不同边坡稳定预测方法的特征信息,改进预测质量,提出了一种基于微粒群优化--支持向量机(PSO-SVM)的边坡稳定性非线性组合预测模型。该模型能够利用边坡的特征参数快速预测出边坡的稳定性,且在建模过程中可对不同建模方法的特征信息进行整合,避免了单一方法的偶然性。为提高SVM的学习、泛化能力,采用混合核函数,并用具有并行性和分布式特点的PSO算法优化选择SVM模型参数。利用该非线性组合预测模型对73个边坡实例进行学习,对另外10个边坡实例进行推广预测,研究结果表明,该模型较好地整合了不同建模方法的特征信息,较单一模型、加权组合模型和BP网络组合模型具有更高的预测精度和更小的峰值误差,为边坡稳定性评价提供了一种新的途径。     

Seasonal Characteristics of Surface Radiation Fluxes on the East Rongbuk Glacier in the Mt.Everest Region

Ground-based measurements are essential for understanding alpine glacier dynamics,especially in remote regions where in-situ measurements are extremely limited.Prom 1 May to 22 July 2005(the spring-summer period),and from 2 October 2007 to 20 January 2008(the autumn-winter period),surface radiation as well as meteorological variables were measured over the accumulation zone on the East Rongbuk Glacier of Mt. Qomolangma/Everest at an elevation of 6560 m a.s.l.by using an automatic weather station(AWS).The...     

潜江凹陷北部潜江组油气分布不均一性及控制因素

通过对潜江凹陷北部潜江组已探明石油储量构成和分布特征的系统分析,总结出油气分布的不均一性及其控制因素。潜江凹陷北部潜江组不同层位、不同区带油气分布差异性明显,具有纵向分隔、横向分散等显著特征。油气的不均一性分布主要受控于3种地质因素:①膏盐韵律发育导致油气纵向分隔,膏盐岩极高的排驱压力有效地限制了流体的垂向运移,油气以侧向运移为主;②成熟烃源岩控制油气富集程度,油气纵向富集程度主要受成熟烃源岩层位的控制,蚌湖向斜带主力生烃灶控制了油气在平面上的富集;③输导条件控制油气的运移方式和纵横向分布范围,高渗砂体的侧向输导能力控制了断层不发育地区油气聚集的规模与平面分布范围,断层的垂向输导作用导致了主干断层发育地区油气在纵向上呈多层系分布。