藏北高原蒸发皿蒸发量及其影响因素的变化特征

采用气候倾向率方法,对藏北高原1971-2006年6个气象站年、季小型蒸发皿蒸发量及其影响气候因子的变化趋势进行了分析。结果表明:近36年藏北高原年蒸发皿蒸发量各站点均呈现显著的减少趋势,平均减少61.7mm/10a(通过99%显著性检验),以夏季减幅最明显。就地域分布而言,蒸发皿蒸发量的下降主要表现在藏北高原的中西部。蒸发量减少幅度随经度的增加减小,随海拔高度的升高而加大。影响蒸发皿蒸发量的主要气候因子日照时数、平均风速呈现显著下降趋势,平均相对湿度、降水量表现为显著增加,平均气温显著升高,平均最低气温的升温速率(0.54℃/10a)明显比平均最高气温的升温速率(0.17℃/10a)大,导致气温日较差的减小(-0.37℃/10a)。藏北高原平均气温日较差和日照时数的显著减小,以及平均相对湿度的明显增加可能是蒸发皿蒸发量显著下降的主要原因,降水量的增加和平均风速的明显减小在蒸发量减少趋势中的作用也不可忽视。     

Circulation of shelf waters in the KwaZulu-Natal Bight,South Africa

Ship-based acoustic Doppler current profiler (S-ADCP) technology, used in survey mode, has enabled near- synoptic views of the in situ 3-D current field in the KwaZulu-Natal (KZN) Bight to be elucidated for the first time. Data acquired by the research vessels RS Africana and RS Algoa in June 2005, September 2007, March 2009 and July 2010 are presented. Each S-ADCP dataset showed similar circulation characteristics whereby the continental slope and outer shelf of the KZN Bight were strongly influenced by the south-westward flowing Agulhas Current. This was particularly evident in the extreme north between Cape St Lucia and Richards Bay where the shelf is narrowest and velocities exceeded 200 cm s?1. The widening of the bight to the south moves the Agulhas Current further from the coast, resulting in a diminishing velocity gradient on the outer shelf which terminates around the midshelf axis. The southern region of the bight was mostly influenced by the Durban cyclonic eddy (Durban Eddy), and in June 2005 and September 2007, by a cyclonic ‘swirl’ that occupied the entire southern half of the KZN Bight, the latter identified by a combination of S-ADCP-, satellite-derived SST- and ocean colour data. Satellite data showed low-chlorophyll offshore water to move into this swirl and northwards along the inner- and midshelf, reaching the Thukela River. Inner-shelf circulation north of the Thukela River was weak (<20 cm s?1) and highly variable. Satellite-tracked surface drogues deployed in the Durban Eddy found their way into the northward coastal current in the KZN Bight, with velocities exceeding 90 cm s?1 at times. The drogues also highlighted the strong influence of wind, especially in the northern bight between Durnford Point and Cape St Lucia, with residence times on the shelf exceeding 14 days, suggesting this region to be of biological importance particularly for recruitment.     

Review of the El Soplao Amber Outcrop,Early Cretaceous of Cantabria,Spain

<正>El Soplao outcrop,an Early Cretaceous amber deposit recently discovered in northern Spain (Cantabria),has been shown to be the largest site of amber with arthropod inclusions that has been found in Spain so far.Relevant data provided herein for biogeochemistry of the amber,palynology,taphonomy and arthropod bioinclusions complement those previously published.This set of data suggests at least two botanical sources for the amber of El Soplao deposit.The first(type A amber)strongly supports a source related to Cheirolepidiaceae,and the second(type B amber)shows non-specific conifer biomarkers.Comparison of molecular composition of type A amber with Frenelopsis leaves(Cheirolepidiaceae)strongly suggests a biochemical affinity and a common botanical origin.A preliminary palynological study indicates a regional high taxonomical diversity,mainly of pteridophyte spores and gymnosperm pollen grains.According to the preliminary palynological data,the region was inhabited by conifer forests adapted to a dry season under a subtropical climate.The abundant charcoalified wood associated with the amber in the same beds is evidence of paleofires that most likely promoted both the resin production and an intensive erosion of the litter,and subsequent great accumulation of amber plus plant cuticles.In addition,for the first time in the fossil record, charcoalified plant fibers as bioinclusions in amber are reported.Other relevant taphonomic data are the exceptional presence of serpulids and bryozoans on the surfaces of some amber pieces indicating both a long exposure on marine or brackish-water and a mixed assemblage of amber.Lastly,new findings of insect bioinclusions,some of them uncommon in the fossil record or showing remarkable adaptations,are reported.In conclusion,a documented scenario for the origin of the El Soplao amber outcrop is provided.     

The linear stability of dilute particulate rings

Irregular structure in planetary rings is often attributed to the intrinsic instabilities of a homogeneous state undergoing Keplerian shear. Previously these have been analysed with simple hydrodynamic models. We instead employ a kinetic theory, in which we solve the linearised moment equations derived in Shu and Stewart 1985 for a dilute ring. This facilitates an examination of velocity anisotropy and non-Newtonian stress, and their effects on the viscous and viscous/gravitational instabilities thought to occur in Saturn's rings. Because we adopt a dilute gas model, the applicability of our results to the actual dense rings of Saturn are significantly curtailled. Nevertheless this study is a necessary preliminary before an attack on the difficult problem of dense ring dynamics. We find the Shu and Stewart formalism admits analytic stability criteria for the viscous overstability, viscous instability, and thermal instability. These criteria are compared with those of a hydrodynamic model incorporating the effective viscosity and cooling function computed from the kinetic steady state. We find the two agree in the ‘hydrodynamic limit’ (i.e., many collisions per orbit) but disagree when collisions are less frequent, when we expect the viscous stress to be increasingly non-Newtonian and the velocity distribution increasingly anisotropic. In particular, hydrodynamics predicts viscous overstability for a larger portion of parameter space. We also numerically solve the linearised equations of the more accurate Goldreich and Tremaine 1978 kinetic model and discover its linear stability to be qualitatively the same as that of Shu and Stewart's. Thus the simple collision operator adopted in the latter would appear to be an adequate approximation for dilute rings, at least in the linear regime.     

Réponse hydrologique d’un bassin semi-aride aux événements pluviométriques et aménagements de versant (bassin du Merguellil,Tunisie centrale)

RÉSUMÉ

L’influence cumulée des aménagements de versants sur les écoulements en zones semi-arides demeure peu étudiée et comprise à l’échelle de grands bassins versants. En Tunisie centrale, nous étudions les variations de la réponse hydrologique du bassin du Merguellil à l’échelle annuelle et pour 114 événements entre 1989 et 2010. Sur cette période, les aménagements de conservation des eaux et des sols ont progressivement drainé de 5% à 30% des surfaces du bassin. L’analyse statistique révèle la forte variabilité des pluies et des débits annuels, mais ne distingue aucune tendance déficitaire. L’approche événementielle démontre que les variations des écoulements annuels sont liées aux apports générés par un nombre très limité (cinq à six par an en moyenne) d’épisodes pluvieux supérieurs à 15 mm. Le nombre très variable de ces évènements ainsi que les écarts importants observés sur leur coefficient de ruissellement (K_R) respectif sont déterminants sur les apports annuels. Pour les événements de plus de 60 mm, les différences d’intensités pluviométriques, de couvert végétal et d’humidité du sol réduisent le ruissellement jusqu’à 80%. Toutefois, les K_R d’averses de moins de 40 mm, sur des sols au couvert végétal et d’humidité semblables, ont également diminué de 45% après l’extension des aménagements de CES à la fin des années 1990.     

On an excitation mechanism for trapped inertial waves in discs around black holes

According to one model, high-frequency quasi-periodic oscillations (QPOs) can be identified with inertial waves, trapped in the inner regions of accretion discs around black holes due to relativistic effects. In order to be detected, their amplitudes need to reach large enough values via some excitation mechanism. We work out in detail a non-linear coupling mechanism suggested by Kato, in which a global warping or eccentricity of the disc has a fundamental role. These large-scale deformations combine with trapped modes to generate 'intermediate' waves of negative energy that are damped as they approach either their corotation resonance or the inner edge of the disc, resulting in amplification of the trapped waves. We determine the growth rates of the inertial modes, as well as their dependence on the spin of the black hole and the properties of the disc. Our results indicate that this coupling mechanism can provide an efficient excitation of trapped inertial waves, provided the global deformations reach the inner part of the disc with non-negligible amplitude.     

Dosage par Spectrométrie de Fluorescence X Du Nickel, du Zinc, du Rubidium, du Strontium, Du Zirconium Et du Niobium dans Trente Standards Geochimiques

Les roahes carbonatées et siliaatées appar-tiement à un domaine de compositions dans lequel la mesure d'un fond libre d'interférence ou d'une rate diffusée du tube peut permettre à la fois de aorriger les effets de pures absorptions et d'étalonner les fonds sous les raies analytiques. Cette propriété est illustrée sur I'exemple du dosage de 6 éléments en traces dans 30 standards géoahimiques.
La méthode proposée permet d'obtenir dans un domaine de concentration de 1 à 2000 ppm des ré-sultats dont la qualité est à rapprocher de la trés grarde rapidité de rmise en oeuvre.     

The Appinite-Migmatite Complex of Sanabria, NW Iberian Massif, Spain

The Sanabria appinitic rocks and host migmatites form an unusual,non-peri-batholithic complex in which all the typical membersof the appinite suite are present. It differs from most appiniticcomplexes in the deeper level of emplacement and the close temporaland spatial association with migmatites. Consequently, manyin situ relationships that resulted from the invasion of maficmagma into a crustal anatectic zone are extremely well preserved.The complex shows unequivocal relations between members of theappinitic suite and between these and migmatites derived byanatexis of a gneissic formation (Ollo de Sapo gneiss). Theserelations point to derivation of monzodiorites and biotite dioritesby hydrous basalt fractionation combined with fluid-assistedmelting of the crustal rocks surrounding the appinitic intrusions.This hydrous basic magma may be derived from an enriched regionof the mantle associated with subduction. Petrogenetic modelshave been tested using a combination of field relations andgeochemical data. Despite the complexity of the processes involved,it is concluded that water played an important role in the petrogenesisof the intermediate and mafic magmas. Reaction between monzodioritemelts and the host migmatites was responsible for the generationof a range of intermediate rocks within the complex. The needfor water to facilitate magma generation in both the mantleand the crust suggests that melting is linked with subduction.This interpretation has important implications because appiniticmagmatism may be considered as indicative of subduction processesinvolved not only in the generation of the mafic end-membersof the suite, but also in the generation of batholiths withwhich the appinitic rocks are spatially and temporally associated. KEY WORDS: appinite; monzodiorite; migmatite; Variscan orogen; Iberian massif     

Spectrum Characteristics and Transfer Function of the Hydrograph of the Deep Aqueous System

The fluctuation of most of the hydrograph in the deep aqueous system records the fluid pulsation in lithosphere and variation of the earth's crust. Many observations have verified that groundwater is an ideal information carrier of the crust. In this paper, the series of input (precipitation, air pressure, Earth tide etc.) and output (water level, artesian flow) of the deep aqueous system are studied by using the spectrum analysis and system theory. The application concepts of transfer function and the spectral structure of the hydrograph enrich the knowledge of the deep aqueous system. Two typical spectral structures of the hydrograph of the deep aqueous system are obtained by comparing with many water-bearing systems of the Jizhong depression. One is from well Ma-17 and the other is from the well Xinze-5. Finally, the physical models of forming the spectrum of the hydrograph are constructed on the basis of the spectrum research on the deep aqueous system.