中国与蒙古之地质

按照构造单元和构造阶段讨论中国和蒙古的演化史。中国前寒武纪地壳演化可分3大阶段:陆核的聚结(2·8Ga);原地台在吕梁运动中固结和侧向增生(1·8Ga);地台在晋宁运动中固化拼合成华夏超大陆(830Ma)。晋宁运动后,中国和蒙古以离散大陆和洋盆并存为特征,至早古生代末聚合为中国和北蒙古两个古大陆。晚古生代时,斋桑—南蒙古—兴安和乌拉尔—天山两大海域陆续消减,形成了海西期的主缝合带。中国蒙古各地块大致于印支运动末期(210Ma)重新聚合,成为劳亚超大陆,即二叠纪—三叠纪泛大陆北支的一部分。印支期后大阶段的特征是泛大陆裂解和大西洋扩张导致了环太平洋域的出现,这一新的构造型式使中国由南北部之间的差异转变为东西部之间的差异。中国东部,也包含蒙古在内,在中—新生代基本上处于张性构造状态,发育张裂盆地和大陆内部火山活动;而在中国西部,中—新生代的构造发展过程则表现为亲冈瓦纳诸地块陆续向北增生拼贴到古亚洲大陆之上。这个过程最终导致了青藏高原在中新世至第四纪的迅速上隆。     

吸湿性播撒对暖性对流云减雨影响的数值模拟

利用以色列特拉维夫大学二维面对称分档云模式（two-dimensional slab-symmetric detailed spectral bin microphysical model of Tel Aviv University）,对2016年9月4日16:00（北京时）前后我国华东地区的一次暖性浅对流云降水过程进行模拟,模式模拟的强回波中心高度和最大回波强度范围与观测基本一致。并在此基础上进行了小于1 μm的吸湿性核的播撒减雨试验,分别考虑了不同播撒时间、不同播撒高度以及不同播撒剂量的敏感性测试。结果表明:在云的发展阶段早期播撒能起到更好的减雨效果,播撒时间越早对大粒子生长过程的抑制作用越强,随着播撒时间向后推移,受抑制作用最显著的粒径段向小粒径端偏移;在云中心过饱和度大的区域下方进行播撒,减雨效果更加明显,当播撒剂量为350 cm-3时,地面累积降水量减少率可达23.3%;另外,随着播撒剂量的增加,减雨效果更加显著,甚至能达到消雨的效果。因此,在暖性浅对流云中合理地播撒小于1 μm的吸湿性核能达到较好的减雨或消雨效果。     

新疆天山山区大气冰核浓度的测量及分析

利用2001年6、7月份在新疆天山山区两个取样点取得的冰核资料，计算了山区中的冰核浓度，研究了冰核平均浓度日变化、日际变化的规律，并分析了天山山区冰核浓度与一些气象因子的关系及可能原因。得出以下结论：天山山区的大气冰核主要来源于地面土壤，比较缺乏；冰核浓度易受气象因子、地表状况的影响，日变化和日际变化明显．     

华北云凝结核分布及与云滴相互作用的观测研究

利用美国DMT公司生产的连续气流单过饱和度云凝结核计数器（DMT—CCN仪）,于2009年4月-7月在华北上空进行云凝结核观测,对不同天气现象下云凝结核的数浓度进行统计分析,研究了云凝结核的垂直分布特征以及水平穿云时云凝结核和云滴的相互作用和演变。     

Dynamical friction on globular clusters in core-triaxial galaxies: is it a cause of massive black hole accretion?

The present work extends and deepens previous examinations of the evolution of globular cluster orbits in elliptical galaxies, by means of numerical integrations of a wide set of orbits in five self-consistent triaxial galactic models characterized by a central core and different axial ratios. These models are valid and complete in the representation of regular orbits in elliptical galaxies. Dynamical friction is definitely shown to be an efficient cause of evolution for the globular cluster systems in elliptical galaxies of any mass or axial ratio. Moreover, our statistically significant sample of computed orbits confirms that the globular cluster orbital decay times are, at least for clusters moving on box orbits, much shorter than the age of the galaxies. Consequently, the mass carried into the innermost galactic region in the form of decayed globular clusters may have contributed significantly to feeding and accreting a compact object therein.     

Atmospheric nuclei in the remote free-troposphere

During May-June of 1990 an extensive flight series to survey aerosol present in the upper-troposphere was undertaken aboard the NASA DC-8 as part of the CLObal Backscatter Experiment (GLOBE). About 50,000 km were characterized between 8–12 km altitude and between 70°N and 58°S. Aerosol with diameters greater than 3nm were counted and sized with a combination of condensation nuclei counters and optical particle counters. Aerosol number and mass concentrations were separately identified with regard to both refractory and volatile components. Regions of the free-troposphere with the lowest mass concentrations were generally found to have the highest number concentrations and appeared to be effective regions for new particle production. These new particle concentrations appear inversely related to available aerosol surface area and their volatility suggests a sulfuric acid composition. The long lifetime of these new particles aloft can result in their growth to sizes effective as CN and CCN that can be mixed throughout the troposphere.     

ON ICE FORMING NUCLEI

Cloud condensation nuclei(CCN)constitute a reservoir of latent ice-forming nuclei(IFN)active by condensation-followed-by-freezing and by sorption.Two classes of aerosol particles active as IFN by sorption werefound.The first produces IFN concentrations which are dependent on temperature only.The IFN concen-tration consecutively increases with lowering of temperature and does not respond to the increasing partialwater vapor pressure.The second produces IFN concentrations which are dependent on partial water vaporpressure only,The IFN concentration consecutively decreases with decreasing of the partial water vapor pres-sure that takes place with the lowering temperature.Sulfates(mostly ammonium sulfate)constitute an integral part of IFN active by condensation-followed-by-freezing and by sorption.Backward isentropic air parcel trajectories linked polluted air rich in sulfates andclean air with high and low concentrations of IFN active by condensation-followed-by-freezing at-19.7℃ andS_w=0.1%.The experiments were performed in a dynamic filter processing chamber with aerosol particles collectedon membrane filters.     

Comparison of Aerosol Effects on Simulated Spring and Summer Hailstorm Clouds

Numerical simulations are carried out to investigate the effect of cloud condensation nuclei(CCN) concentrations on microphysical processes and precipitation characteristics of hailstorms. Two hailstorm cases are simulated, a spring case and a summer case, in a semiarid region of northern China, with the Regional Atmospheric Modeling System. The results are used to investigate the differences and similarities of the CCN effects between spring and summer hailstorms. The similarities are:(1) The total hydrometeor mixing ratio decreases, while the total ice-phase mixing ratio enhances, with increasing CCN concentration;(2) Enhancement of the CCN concentration results in the production of a greater amount of small-sized hydrometeor particles, but a lessening of large-sized hydrometeor particles;(3) As the CCN concentration increases, the supercooled cloud water and rainwater make a lesser contribution to hail, while the ice-phase hydrometeors take on active roles in the growth of hail;(4) When the CCN concentration increases, the amount of total precipitation lessens,while the role played by liquid-phase rainfall in the amount of total precipitation reduces, relatively, compared to that of icephase precipitation. The differences between the two storms include:(1) An increase in the CCN concentration tends to reduce pristine ice mixing ratios in the spring case but enhance them in the summer case;(2) Ice-phase hydrometeor particles contribute more to hail growth in the spring case, while liquid water contributes more in the summer case;(3) An increase in the CCN concentration has different effects on surface hail precipitation in different seasons.     

The Increase of Biogenic Sulfate Aerosol and Particle Number in Marine Atmosphere over the Northwestern North Pacific

During a cruise aboard the R/V Hakuho-maru in the northwestern North Pacific in the summer of 1998 the particle number concentrations and the major ionic components of size fractionated aerosols were measured to investigate the aerosol produced by marine biological activity. Continuous low concentrations of nitrate (<1.8 nmol m⁻³), similar to the marine air background level, were found over the northwestern North Pacific (40–45°N) and the Sea of Okhotsk (44–45°N). Over the Sea of Okhotsk, a high concentration of chlorophyll-a (5.4 mg m⁻³) in seawater was observed, and atmospheric concentrations of non sea-salt (nss-) sulfate (44 nmol m⁻³), methane sulfonic acid (MSA) (1.8 nmol m⁻³) and particle number in the size range of 0.1 < D < 0.5 μm (199 cm⁻³) were found to be 9, 7, and 2 times, respectively, higher than those in the background marine air. The increase in particle number concentrations mainly in the size range of 0.2 < D < 0.3 μm was likely caused by the increase of biogenic sulfate over the high productive region of the Sea of Okhotsk. In humid air conditions (R.H. > 96%), the increased biogenic sulfate that condensed the large amount of water vapor would not have sufficient solute mass to activate as cloud condensation nuclei (CNN) and would remain as aerosol particles in the marine air with frequent sea-fogs over the high productive region. Biogenic sulfate originating from dimethyl sulfide (DMS) would gradually grow into the CCN size and continuously supply a great number of CCN to the marine air in the northwestern North Pacific. This revised version was published online in July 2006 with corrections to the Cover Date.     

An Infrared Photometric Study of Galaxies with Extragalactic H2O Maser Sources

All galaxies with extragalactic H_2O maser sources observed so far are collected. With the 2MASS and the IRAS photometric data an infrared study is performed on those galaxies.By a comparison between the H_2O maser detected sources and non-detected sources in the infrared it is indicated that infrared properties in the IRAS 12-25μm and 60-100μm are important for producing H_2O masers in galaxies.It is also found that the H_2O maser galaxies with different nuclear activity types have rather different infrared properties mainly in the IRAS 12-60μm region.