基于HYSPLIT4的一次四川盆地夏季暴雨水汽路径和源地分析

利用四川省156站气象资料、全球同化系统(GDAS)资料,引入拉格朗日混合单粒子轨道模型(HYSPLIT4),定量分析了2013年7月7—11日四川盆地西部暴雨的水汽输送情况。结果表明：此次暴雨过程的水汽主要来自950和850 hPa,并且两者的水汽路径和来源有着显著差别。后向追踪1天,950和850 hPa的水汽来源大值区都出现在四川盆地区;追踪3天,950 hPa的水汽来源大值区仍然在四川盆地附近,但是850 hPa上则追踪到孟加拉湾东部;追踪到9天时,950 hPa的水汽主要来源出现在阿拉伯海到我国南海地区,850 hPa上则追踪到索马里半岛东部。总体上950 hPa的水汽输送路径有五条,其中两条是北方路径,另外三条为南方路径。850 hPa的水汽输送路径有两条,一条是北方路径,另一条是南方路径。定量分析指出,950 hPa的水汽源地主要有四个,其中阿拉伯海—孟加拉湾地区的水汽输送贡献率最大（44.1%）,中南半岛—南海地区的水汽贡献率次之（33.1%）,巴尔喀什湖地区（15.7%）和贝加尔湖地区（7.1%）的水汽贡献率相对较弱。850 hPa上的水汽源地也有四个,其中从阿拉伯海地区,沿南亚夏季风爆发路径而来的暖湿空气最重要（89.4%）,其次从西北部巴尔喀什湖—贝加尔湖地区而来的干冷空气相对较弱（6.3%）,而来自孟加拉湾（3%）和局地（1.3%）的水汽则非常少。     

基于DBBC＋Mark5B记录系统的脉冲星观测

2009年11月,云南天文台射电天文研究团组采用40m射电望远镜以及基于DBBC（Digital Base Band Conveter）和Mark5B的VLBI记录系统对PSRJ08354510和PSRJ0332＋5434进行了观测。观测选用S波段右旋圆极化信号,起始频率为2206．99MHz,总带宽为32MHz。对数据进行相干消色散和平均后,得到PSRJ0332＋5434的单脉冲图像和两颗脉冲星的平均脉冲轮廓。由平均轮廓的展宽随时间的变化关系,对脉冲星的视周期作了一定修正后,得到信噪比更高的平均轮廓图。最后对轮廓的信噪比随时间的变化作了初步分析,由此可了解整个系统在观测时的稳定性。     

Cassini SAR, radiometry, scatterometry and altimetry observations of Titan’s dune fields

Large expanses of linear dunes cover Titan’s equatorial regions. As the Cassini mission continues, more dune fields are becoming unveiled and examined by the microwave radar in all its modes of operation (SAR, radiometry, scatterometry, altimetry) and with an increasing variety of observational geometries. In this paper, we report on Cassini’s radar instrument observations of the dune fields mapped through May 2009 and present our key findings in terms of Titan’s geology and climate. We estimate that dune fields cover ∼12.5% of Titan’s surface, which corresponds to an area of ∼10 million km², roughly the area of the United States. If dune sand-sized particles are mainly composed of solid organics as suggested by VIMS observations (Cassini Visual and Infrared Mapping Spectrometer) and atmospheric modeling and supported by radiometry data, dune fields are the largest known organic reservoir on Titan. Dune regions are, with the exception of the polar lakes and seas, the least reflective and most emissive features on this moon. Interestingly, we also find a latitudinal dependence in the dune field microwave properties: up to a latitude of ∼11°, dune fields tend to become less emissive and brighter as one moves northward. Above ∼11° this trend is reversed. The microwave signatures of the dune regions are thought to be primarily controlled by the interdune proportion (relative to that of the dune), roughness and degree of sand cover. In agreement with radiometry and scatterometry observations, SAR images suggest that the fraction of interdunes increases northward up to a latitude of ∼14°. In general, scattering from the subsurface (volume scattering and surface scattering from buried interfaces) makes interdunal regions brighter than the dunes. The observed latitudinal trend may therefore also be partially caused by a gradual thinning of the interdunal sand cover or surrounding sand sheets to the north, thus allowing wave penetration in the underlying substrate. Altimetry measurements over dunes have highlighted a region located in the Fensal dune field (∼5° latitude) where the icy bedrock of Titan is likely exposed within smooth interdune areas. The hemispherical assymetry of dune field properties may point to a general reduction in the availability of sediments and/or an increase in the ground humidity toward the north, which could be related to Titan’s asymmetric seasonal polar insolation. Alternatively, it may indicate that either the wind pattern or the topography is less favorable for dune formation in Titan’s northern tropics.     

Optimal dynamos in the cores of terrestrial exoplanets: Magnetic field generation and detectability

A potentially promising way to gain knowledge about the internal dynamics of extrasolar planets is by remote measurement of an intrinsic magnetic field. Strong planetary magnetic fields, maintained by internal dynamo action in an electrically conducting fluid layer, are helpful for shielding the upper atmosphere from stellar wind induced mass loss and retaining water over long (Gyr) time scales. Here we present a whole planet dynamo model that consists of three main components: an internal structure model with composition and layers similar to the Earth, an optimal mantle convection model that is designed to maximize the heat flow available to drive convective dynamo action in the core, and a scaling law to estimate the magnetic field intensity at the surface of a terrestrial exoplanet. We find that the magnetic field intensity at the core surface can be up to twice the present-day geomagnetic field intensity, while the magnetic moment varies by a factor of 20 over the models considered. Assuming electron cyclotron emission is produced from the interaction between the stellar wind and the exoplanet magnetic field we estimate the cyclotron frequencies around the ionospheric cutoff at 10 MHz with emission fluxes in the range 10⁻⁴-10⁻⁷ Jy, below the current detection threshold of radio telescopes. However, we propose that anomalous boosts and modulations to the magnetic field intensity and cyclotron emission may allow for their detection in the future.     

鄂尔多斯盆地深部富铀烃源岩提供铀源可能性的实验研究

鄂尔多斯盆地上三叠统延长组长7段石油优质烃源岩以富铀为特色,而盆地侏罗?白垩纪地层以赋存大量砂岩型铀矿而著称.为探索深部长7富铀烃源岩为浅部砂岩型铀矿形成提供铀源的可能性,选择盆地南部的富铀烃源岩、油样以及具有代表性的碳酸铀酰作为反应物,在中?高温高压还原条件下分别进行烃源岩生排烃?排铀模拟实验和油?铀关系模拟实验.结...     

末次盛冰期末期以来南海北部陆坡的陆源物质输入及其控制因素

通过对南海北部陆坡KNG5孔沉积物粒度、粘土矿物和14C年龄的综合分析, 探讨了南海北部陆坡的沉积物来源及其控制因素。物源分析表明, KNG5孔17.5-12.5ka BP的沉积物主要来源于珠江, 12.5ka BP 时粘土矿物组合突然发生改变, 并且自12.5ka BP以后, 高岭石含量总体稳定, 说明12.5ka BP时海平面已上升到相当的高度, 并且可能当时南海的现代环流系统已开始形成, 西行的广东沿岸流导致向外扩散的珠江物质减少, 由于受北太平洋深层水(NPDW)和黑潮(KC)南海分支的作用, 台湾成为此时沉积物的主要贡献者。KNG5孔17.5-11ka BP时期的粘土矿物和粒度变化主要受控于海平面和洋流系统的变化。全新世早期(11.0-8ka BP)平均粒径达到最细和1-2.2m 粒级含量达到最高值可能是强盛的夏季风作用的结果。全新世中晚期(8—0ka BP) 1-2.2?m组分含量的减少是8ka BP以来东亚夏季风减弱的具体体现, 1-2.2m 粒级含量指示的东亚夏季风变化能和北半球其它季风指标能很好地对应起来, 说明这次季风减弱是北半球各个季风系统的共同现象。     

Sedimentary Environments of Cambrian–Ordovician Source Rocks and Ultra-deep Petroleum Accumulation in the Tarim Basin

The Tarim Basin is the only petroliferous basin enriched with marine oil and gas in China. It is presently also the deepest basin for petroleum exploration and development in the world. There are two main sets of marine Source Rocks (SRs) in the Tarim Basin, namely the high over-mature Cambrian–Lower Ordovician (∈–O1) and the moderately mature Middle–Upper Ordovician (O2–3). The characteristic biomarkers of SRs and oils indicate that the main origin of the marine petroleum is a mixed source of ∈–O1 and O2–3 SRs. With increasing burial, the hydrocarbon contribution of the ∈–O1 SRs gradually increases. Accompanied by the superposition of multi-stage hydrocarbon-generation of the SRs and various secondary alteration processes, the emergence and abnormal enrichment of terpenoids, thiophene and trimethylaryl isoprenoid in deep reservoirs indicate a complex genesis of various deep oils and gases. Through the analysis of the biofacies and sedimentary environments of the ∈–O1 and O2–3 SRs, it is shown that the lower Paleozoic high-quality SRs in the Tarim Basin were mainly deposited in a passive continental margin and the gentle slope of the platform, deep-water shelf and slope facies, which has exhibited a good response to the local tectonic-sedimentary environment. The slope of the paleo-uplift is the mutual area for the development of carbonate reservoirs and the deposition of marine SRs, which would be favorable for the accumulation of petroleum. Due to the characteristics of low ground temperature, the latest rapid and deep burial does not cause massive oil-cracking in the paleo-uplift and slope area. Therefore, it is speculated that the marine reservoirs in the slope of the Tabei Uplift are likely to be a favorable area for deep petroleum exploration, while the oil-cracking gas would be a potential reserve around the west margin of the Manjiaer Depression. Hydrocarbons were generated from various unit SRs, mainly migrating along the lateral unconformities or reservoirs and the vertical faults. They eventually brought up three major types of exploration fields: middle and lower Cambrian salt-related assemblages, dolomite inner reservoirs and Middle and Lower Ordovician oil-bearing karst, which would become the most favorable target of marine ultra-deep exploration in the Tarim Basin.     

塔里木盆地英买力地区原油地球化学特征与族群划分

塔里木盆地英买力地区油气成因复杂,采用多馏分、多组分化学成分分析及单体烃碳同位素分析途径,对该区海相、陆相油进行精细分析。结果表明,英买力油田主要有两大类油组,分别是南部YM2井区的海相油(I类)和北部YM7井区的陆相油(Ⅱ类),各自具有典型的海相油与陆相油的特征。进一步分析表明,两大油组内部仍有分异。将第二油组进一步分为两亚类,以中、古生界产层为主的正常黑油和重质油为一类(Ⅱa),以古近系为主的凝析油为另一类(Ⅱb)。两亚类原油正构烷烃单体烃同位素稍有差异,芳烃组成与分布具有显著差异。较之于Ⅱa原油,Ⅱb原油富含联苯系列与氧芴系列、不同类型芳烃系列中以低分子量同系物占绝对优势,其正构烷烃单体烃碳同位素更重,与相邻的羊塔克地区原油表现出一定的相似性,表明两者之间有一定的成因联系,前者可能为混源油,由位于库车坳陷中拜城凹陷提供两种陆相烃源岩。英买力地区陆相油并非以往确认的一种成因类型,可能至少由两套性质迥异的中生界烃源岩供烃。英买力地区第一类海相油(I类)尽管生物标志物特征相近,但分析原油的单体烃碳同位素具有显著差异,同样存在油气混源的可能。英买力地区海、陆相原油特征与成因的深入剖析,对于该区精细油源确认、油气成藏机制乃至油气资源评价具有重要意义。     

Source apportionment and distribution of atmospheric mercury in urban Beijing,China

The concentration of gaseous elemental mercury (GEM) in the atmosphere of urban Beijing was measured from October 2003 to September 2004 to investigate the origins and spatial-temporal variations of atmospheric Hg. The mean value of Hg concentration is 17.1 ng·m-3 (n=653). The atmospheric Hg data showed spatial-temporal variations throughout the duration of our observation. The maximum GEM concentration (53.7 ng·m-3) was observed at Gucheng in the western area of urban Beijing. The GEM concentrations increased from the north to the south of the studied area, and were higher in winter than in summer. The highest and lowest monthly averages of GEM concentrations were measured to be 23.3 and 4.1 ng·m-3 in January and July, respectively. In addition, GEM concentrations are higher in the daytime than at night in Autumn and from 14 March to 15 April, but daily GEM variation showed an inverse pattern from 22 April to 22 May. In winter, two peak values of GEM concentrations occurred at 13:30 and 21:30. Daily variation of GEM concentrations in summer was the lowest in the four seasons. Mercury from coal combustion was estimated to be the main source of anthropogenic emissions in Beijing from October 2003 to September 2004. Additionally, Hg emission from natural gas burning was estimated to be another dominant source of atmospheric Hg in Beijing.     

福建沿海地区表层土壤铅来源及分布特征

在福建省沿海经济带生态地球化学调查的基础上,应用富集因子法对福建省沿海地区表层土壤中铅的来源进行了分析,并对其自然来源和人为来源的分布特征及影响因素做了初步探讨。结果表明,福建沿海地区约98.2%的土地面积表层土壤中铅属于自然来源,其余地区含有人为来源铅,且集中分布于个别市县城区;铅自然来源区呈现广域性分布特征,人为来源区则呈现零星的斑点状分布特点;铅自然来源区和人为来源区的空间分布特征在很大程度上受到土壤类型、森林植被分布以及人为活动等因素的影响。