低轨道人造卫星(CHAMP、GRACE、GOCE)与高精度地球重力场——卫星重力大地测量的最新发展及其对地球科学的重大影响

评述了卫星重力大地测量的最新发展及其对地球科学的重大影响。为了更好地理解地球内部物理构造与海洋动力学，以及大陆，冰川和海洋的相互作用，改善现有地球重力场模型（包括精度和空间解析度）是非常重要的。IUGG等国际组织对此已经强调了很多年。最近，由德国的GFZ（GeoForschungsZentrum)，美国的NASA（National Aeronautics and Space Adminitration)以及欧洲宇航局ESA（European Space Agency)开发研制了最先进的地球监测技术－SST（Satellite-to-Sateilite Tracking)。其主要特点是利用现有的GPS连续追踪新发射低轨道卫星，并由低轨道卫星对地球重力场作精密观测。已经发射和即将发射的卫星有3颗：GHAMP（Challenging Mini-Satellite Payload for Geophysical Research an Application)已经于2000年发射；GRACE（Gravity Recovery and Climate Experimert)定于2002年发射；GOCE（Gravity Field and Steady-state Ocean Cirulation Explorer)计划2004年发射，它们可以统称为重力卫星。载有SST技术的人造卫星的主要目的是获得具有前所未有的高精度和高空间解析度的全球重力场和大地水准面模型，加强人们对地球内部构造的理解并为海洋和气象研究提供更好地参考。上述3个重力卫星工作在有明显区别的不同波谱内，它们有不同的科学应用，仅有一小部分重合。所以，就应用而言它们是完全互补的。它们在地球科学中的应用将是广泛的，特别对于固体地球物理学，海洋学以及大地测量学等领域，它们将会带来革命性的变化，其意义不亚于GPS。     

亚毫米波射电天文用超导SIS接收机的研制(英文)

为了研制亚毫米波射电天文用超导SIS(超导 -绝缘体 -超导 )接收机 ,我们重点开展了如下研究 ,1 )Nb超导SIS结在其能隙频率附近的量子混频特性 ,及其结合高能隙超导薄膜 (NbTiN)和高电导率金属薄膜 (Al)分布结阵在 780 - 950GHz频率区间的量子混频特性 ;2 )亚毫米波超导混频器嵌入阻抗的数值和实验表征 ;3)高电流密度小面积Nb超导SIS结的制备和特性表征 ;4)一个 60 0 - 72 0GHz超导SIS混频器的研制和特性表征。本文详细介绍了相关的数值分析和实验测量结果。     

PROPAGATION OF 30—60 DAY LOW FREQUENCY OSCILLATIONS AND THEIR INFLUENCE UPON THE SUBTROPICAL WESTERLIES JET STREAM DURING NORTHERN HEMISPHERE WINTER

Based on daily ECMWF gridpoint data of two winters during 1981—1983 including an ENSOyear,propagation of low frequency oscillations(LFO)during Northern Hemisphere winters andtheir influences upon 30—60 day oscillations of the subtropical jet stream are studied with the sta-tistical methods as complex empirical orthogonal function(CEOF)and so on.Results show that inthe winter of a normal year(1981—1982),30—60 day oscillations in the subtropical zone aremainly in the northern and southern flanks of exit region of jet stream.In the ENSO year(1982—1983),they are mainly in the vicinity of entrance and exit regions of jet stream.Intraseasonalchanges of subtropical jet stream manifested themselves as latitudinal fluctuation or longitudinalprogression or regression of about 40 day period.There are marked differences between propagat-ing passages of low frequency modes responsible for changes of subtropical jet stream in the normalyear(1981—1982)and in the ENSO year(1982—1983).Changes of oscillation amplitude showobvious phases.In general,the one in late winter is stronger than that in early winter,strongestone occurs in February.     

Evolution of 2:1 layered silicates in low-grade metamorphosed Liassic shales of Central Switzerland

White mica from the Liassic black shales and slates in Central Switzerland was analysed by transmission electron microscopy (TEM) and electron microprobe to determine its textural and compositional evolution during very low-grade prograde metamorphism. Samples were studied from the diagenetic zone, anchizone and epizone (T ≈100°–450 °C). Phyllosilicate minerals analysed include illite/smectite (I/S), phengite, muscovite, brammallite, paragonite, margarite and glauconite. Textural evolution primarily is towards larger, more defect-free grains with compositions that approach those of their respective end-members. The smectite-to-illite transformation reduced the amounts of the exchange components SiK_?1Al_?1, MgSiAl_?2, and Fe³⁺Al_?1. These trends continue to a lesser degree in the anchizone and epizone. Correlations between the proportion of smectite in I/S and the composition of I/S indicate that smectite layers may contain a high layer charge. Illite in I/S bears a compositional resemblance to macrocrystalline phengite in some samples, but is different in others. Paragonite first appears in the upper diagenetic zone or lower anchizone as an interlayer-deficient brammallite, and it may be mixed with muscovite on the nanometre scale. Owing to the small calculated structure factor for paragonite-muscovite superstructures, conventional X-ray powder diffraction cannot distinguish between mixed-layer structures and a homogeneous compositionally intermediate solid solutions. However, indirect TEM evidence shows that irregularly shaped domains of Na- and K-rich mica exist below 10 nm. Subsequent coarsening of domains at higher grades produced discrete paragonite grains at the margins of muscovite crystals or in laths parallel to the basal plane of the host muscovite. Margarite appears in the epizone and follows a textural evolution similar to paragonite in that mixtures of margarite, paragonite, and muscovite may initially occur on the nanometre scale. However, no evidence of interlayer-poor margarite has been found.     

Massive disks in low surface brightness galaxies

An update of the set of low surface brightness galaxies is presented which can be used to set constraints on the otherwise ambiguous decompositions of their rotation curves into contributions due to the various components of the galaxies. The selected galaxies show all clear spiral structure and arguments of density wave theory of galactic spiral arms are used to estimate the masses of the galactic disks. Again these estimates seem to indicate that the disks of low surface brightness galaxies might be much more massive than currently thought. This puzzling result contradicts stellar population synthesis models. This would mean also that low surface brightness galaxies are not dominated by dark matter in their inner parts. This revised version was published online in August 2006 with corrections to the Cover Date.     

Circulation in the Gulf of Aqaba (Red Sea) during winter—spring

This study is devoted to oceanographic features of the semi-enclosed Gulf of Aqaba, Red Sea. The data were recorded in winter—spring 1999 on the R/V Meteor cruise leg 44/2. Temperature and salinity profiles were measured at six positions (I—VI). The shipboard NarrowBand Acoustic Doppler Current Profiler (NB ADCP) 150 kHz continuously recorded current profiles down to 350 m en route. The research revealed that the current near the Strait of Tiran front (position VI) represents a semidiurnal signal of an internal tide wave (∼12 h period; 0.2 ms⁻¹ amplitude) that might be generated by the barotropic tide at the sill of the Strait. A sequence of cyclonic and anticyclonic eddy pairs is found along the axis of the Gulf of Aqaba during winter-spring seasons. These sub-mesoscale signals are dominant above the main thermocline and might be caused by wind forcing and the narrowness of the Gulf; it might remain in other seasons with different dimensions in relation to the depth of thermocline. The total diameter of each pair was twice the baroclinic Rossby radius (R ≈ 10 km). A single anti-cyclonic eddy was observed in the upper 300 m in the northern tip of the Gulf with a diameter of about 5–8 km.     

CO<Subscript>2</Subscript> Flux Measurements over the Sea Surface by Eddy Correlation and Aerodynamic Techniques

The measurements of the vertical transport of CO₂ were carried out over the Sea of Japan using the specially designed pier of Kyoto University on September 20 to 22, 2000. CO₂ fluxes were measured by the eddy correlation and aerodynamic techniques. Both techniques showed comparable CO₂ fluxes during sea breeze conditions: −0.001 to −0.08 mg m⁻²s⁻¹ with the mean of −0.05 mg m⁻²s⁻¹. This means that the measuring site satisfies the fetch requirement for meteorological observations under sea breeze conditions. Moreover, the eddy diffusivity coefficient used in the aerodynamic technique is found to be consistent with the coefficient used in the eddy correlation technique. The present result leads us to conclude that the aerodynamic technique may be applicable to underway CO₂ flux measurements over the ocean and may be used in place of the bulk technique. The important point is the need to maintain a measuring accuracy of CO₂ concentration difference of the order of 0.1 ppmv on the research vessels or the buoys.     

海水中234Th的超低水平液闪谱仪测定

本文提出了利用超低水平液闪谱仪测定海水中234Th的方法.海水经氢氧化铁吸附共沉淀富集后,接着用阴离子交换和TBP/煤油萃取进行Th同位素的分离与纯化.对一系列测定条件进行了详细的研究,提出了测定海水中234Th的适宜程序,即在含有234Th和产额示踪剂230Th的纯化后的5mol/dm3HNO3溶液中加入TBP/煤油进行萃取,然后用0.1mol/dm3HNO3反萃取,后者是先用契伦柯夫计数法测量234Th(通过234mPa),后加入闪烁液Hisafe 3用α/β模式测量α放射体230Th.对于α和β放射体液闪谱仪的计数效率分别为100%和55.7%±2.7%.234Th的化学回收率和总探测效率分别为70%～80%和30%～45%.该法测定海水中的234Th快速、简便和高效.     

夏季南海上层环流动力机制的数值研究

通过利用一个分区性的正压-斜压衔接模式来探讨夏季南海的上层环流特征及其动力机制,结果表明:夏季期间,由于风生环流的不稳定性促使在东沙群岛附近的气旋涡的强度及位置发生变化,并间接导致黑潮侵入南海北部的程度变化以及气旋涡南侧的反气旋式环流、西沙群岛西南侧的气旋涡的强度和范围出现波动现象;在南海南部的北向西边界流由于离岸的西南季风所驱动在中南半岛中部沿岸脱离岸线往东北方向的流动,导致沿岸的水体大量流失而在沿岸形成一支南向补偿流并在西沙群岛西南侧诱生一气旋涡,而上述的离岸西边界流则作顺时针方向流动,从而在南海南部形成反气旋式大环流;在南沙海槽附近出现的局地气旋涡和万安滩附近的气旋涡分别受β效应、底形效应的作用而形成.     

三维斜压模式对冬季南海环流的数值计算

用一个三维、自由表面、原始方程模式对南海环流进行了计算.计算结果表明:黑潮在巴士海峡以西呈一反气旋弯曲流动路径,有一相对高温高盐的水舌从巴士海峡伸入南海,表明有部分黑潮水侵入南海.冬季南海的一些观测事实在模式结果里得到了很好的反映,像冬季逆风向东北方向流动的“南海暖流”和一些中尺度涡旋.同时还分析了巴士海峡沿120.75°E断面的流速和盐度的垂直结构,并同观测结果进行了比较.根据模式结果,我们还进一步讨论了“南海暖流”的形成和驱动机制.