Yearly variations in runoff as a function of precipitation variations for the East-European plain

Variations in climatic conditions for the East-European Plain (EEP) are analysed. The observations show that the time periods of high-water and low-water correspond to certain circulation conditions, which points to a conceptual possibility to construct a model correlating streamflow with atmospheric precipitation. Described is a linear model based on a regression equation for the principal components of runoff and precipitation. The model presents the best results for a territory where a strong reaction of the river water to a certain circulation type has been established beforehand.     

Climatic variations in China during the quaternary

Climatic variations in China during the Quaternary have long been a question of debate. Considerable data now available support Professor Li Siguang's (J. S. Lee) suggestion that there were four glacial periods. In this later years the views of Professor Li have received support from more recent information demonstrating that a further glacial period and periglacial phenomena preceded the Boyang Period.During the Quaternary 3,500,000 years ago there were a number of climatic fluctuations in China, having an amplitude of over 10°C and a cycle of 10⁴ to 10⁵ years. Each fluctuation lasted from the onset of one glacial period to that of the next, encompassing a glacial period and an interglacial. Tab 1 provides a comparison between the glacial periods in China during the Quaternary and those in other regions of the world.     

Temporal variations in the position of the heliospheric equator

It is shown that the centroid of the heliospheric equator undergoes quasi-periodic oscillations. During the minimum of the 11-year cycle, the centroid shifts southwards (the so-called bashful-ballerina effect). The direction of the shift reverses during the solar maximum. The solar quadrupole is responsible for this effect. The shift is compared with the tilt of the heliospheric current sheet.     

Long-term variations in the rotation of the solar corona

The characteristic time scales for variations in the differential rotation of the solar corona are determined using measurements of the intensity of the FeXIV 5303 Å coronal line made from 1939–2004. Drift waves of the variations in the rotational speed with an 11-year periodicity can be distinguished. Moving averages with time intervals from two to five years are used to identify torsional waves. In addition, longer-period variations in the rotational speed can be distinguished when longer averaging intervals are used. When the interval used for the moving average is increased to 8–12 years, a quasi-22-year rotational period appears. The low-latitude corona rotates more slowly in odd cycles than in even cycles. Increasing the duration of the averaging interval further shows that rapid rotation at low latitudes was observed in 1940–1950 and 1990–2000, while slow rotation was observed in 1960–1980, possibly suggesting the presence of a 55-year period in the rotational variations. Long-term variations are found in the rotation of polar regions. The rotational variations for high-latitude corona are in antiphase with those for the low-latitude corona. The origins of zones of anomalous coronal rotation and their dynamics in the global activity cycle are discussed.     

Holocene lake level variations on the Qinghai-Tibetan Plateau

Paleoshorelines indicative of multiple high lake stages can be found around many lakes on the Qinghai-Tibetan Plateau (QTP). Conspicuous paleoshorelines associated with the most recent highstands can be readily observed on satellite images and during field investigations. However, earlier paleoshorelines have been identified at only a few sites around these lakes due to a lack of clear shoreline features and limited spatial extension of those that can be identified. We investigated past lake highstands using published chronologies, Aster-DEM, Google Earth, and ArcGIS 9.2 software. These data suggest that (1) paleoshorelines of the most recent lake highstand were formed during the Holocene; (2) during this highstand, lake levels reached more than 90, 60–90, and 30–60 m higher than present in the central Gangdise and western Qiangtang areas, while in the eastern Qiangtang, Holxil-Yushu, and northeastern QTP areas highstands did not exceed 30 m above modern; (3) during the early Holocene, some lakes on the southwestern QTP combined to form large lakes, while lakes in the inland areas of the QTP were only a little larger during the Holocene high lake level stages.     

Regional and local variations in the composition of the wolframite series from SW Japan and possible factors controlling compositional variations

The regional and local variations in the composition of the wolframite series associated with the ilmeniteseries and magnetite-series granitoids in the Inner Zone of SW Japan were investigated using X-ray diffraction and microprobe analyses. It is concluded that the variation in Mn/Fe ratios in the source materials (granitic magmas in most cases) is the dominant factor controlling the regional variation in the wolframite compositions, while, as exemplified by the Kaneuchi mine, Kyoto Prefecture, the wallrock chemistry and pH of ore fluids are responsible for the local variation within a single vein system. Within a fresh euhedral crystal from the mine, only slight compositional variation of less than 3 mole% MnWO₄ is found in the form of oscillatory zoning. This study, combined with the fluid inclusion research, indicates that the wolframite compositions (Mn/Fe ratios) cannot be used as a geothermometer.     

Quasi-biennial variations in the total NO2 content

Doklady Earth Sciences -     

Lateral variations of the mid-mantle conductance beneath Europe

Europe is a region with the largest density of geomagnetic observatories and several authors have used these data to estimate local geomagnetic response functions for various period ranges, typically of the width of 1.5 to 2.5 decades. By collecting the local response functions from 35 European observatories, and by their precise selection and subsequent combination, the independent regional geomagnetic induction data set could be extended to a period range of 4.5 decades. The initial local responses that were estimated by two magnetovariation methods, with two different external source fields employed, have been further supplemented by continental and global 11-year data, providing thus a data set extending over a period range from the harmonics of the daily variations up to 11 years. The combined responses have been inverted individually for each observatory by two techniques, by an Occam procedure and a stochastic 1D inversion for spherically symmetric Earth. The integrated mantle conductance has revealed rather regular lateral changes that have been used to design a mantle conductance image down to a depth of about 770 km. The presented conductance image can be correlated with major European tectonic units like the Baltic Shield and the Trans-European Suture Zone.To examine possible distortions to the inferred mantle conductance models due to large-scale near-surface heterogeneities, specifically those caused by the oceans, seas and large sedimentary basins, a spherical forward modeling was carried out for a radially symmetric conductor coated by an inhomogeneous thin shell with the variable surface conductance. The model responses for the 35 observatory positions were inverted in the same way as previously the experimental data. The results for 28 observatories have shown that the depth down to a pre-defined conductance level could be retrieved with a high accuracy of a few percents, but for seven southernmost observatories the recovery error increased up to 9%. With these seven observatories removed from the analysis, the effect of the seas and oceans on the upper and mid-mantle conductance estimates beneath Europe can be considered negligible.     

Orbital-period variations in the eclipsing binary Y Cam

We have studied the time behavior of the orbital period and the primary’s pulsation period for the eclipsing binary system Y Cam, whose secondary fills its Roche lobe and whose primary is a δ Scuti star. The times of minima available for this eclipsing binary cover 120 years. δ Scuti pulsations of the primary have been observed over the last 50 years, with the period of these pulsational brightness variations remaining virtually unchanged during the entire observed time interval. The large-amplitude cyclic variations of the orbital period of Y Cam cannot be explained solely by the presence of a third body in the system. It is possible to explain the period variations of Y Cam with magnetic oscillations or a superposition of a stationary matter flow from the lower-mass to the higher-mass component together with magnetic oscillations, similar to the case of AB Cas. A good agreement with observations is provided by a model assuming a stationary matter flow from the secondary filling its Roche lobe to the primary, at the rate of 2.85 × 10^?7 M _⊙/year, superposed with irregular period jumps that can be explained by instabilities in the matter flow. We have detected cyclic variations of the orbital period of Y Cam with an amplitude of 0.011^d, which can be understood if the binary moves in a long-period orbit (with a period of 38.6 years) around a third body with mass M ₃ s> 0.30M _⊙. These cyclic period variations of the eclipsing binary agree with the observed small period variations of the δ Scuti pulsations.     

Isotopic variations of the nitrogen in Lake Superior

The isotopic compositions of nitrogen in lake water, plankton samples and the organic-N fractions extracted from sediments at selected stations in Lake Superior are presented. The δ¹⁵N values of the Kjeldahl total-N and acid hydrolyzable-N in the lake sediments are similar (range, +4.7–+6.7; mean, +5.5 %.). The δ¹⁵N data for the various extracts are independent of the age and concentration of nitrogen in the sediments. On the other hand, the δ¹⁵N values of lake water (+ 0.6‰), phytoplankton (+ 1.6 %.) and Zooplankton (+ 5.0‰) in the water column suggest significant discrimination against the heavier nitrogen isotope in the food chain of the lacustrine environment. The data emphasize the need for a better understanding of the autogenous isotopic fractionation before the isotopic method can be used to fingerprint the sources of nitrogen in a limnetic ecosystem.     

Structural variations in anorthites

Variations of structure and optical properties in anorthites (An 93–97%) of different origin are analyzed with the petrographic microscope, U-stage methods, X-ray single crystal analysis and high voltage electron microscopy. No significant variation has been found in the orientation of the indicatrix and of the lattice constants. But c-type reflections (h + k even, odd) are strong and sharp in anorthites from slowly cooled rocks and diffuse in anorthites of identical chemical composition from quenched igneous rocks. Large type c-antiphase domains (5000–10000 Å) are found in the slowly cooled rocks, c-domains in volcanic rocks are small (100 Å) or could not be imaged. The presence of only b-domains in lunar basalt 14310 indicates quenching of this rock. Large c-domains in the Apollo 15 genesis rock (15415, Lally et al., 1972) indicate slow cooling similar to terrestrial metamorphic rocks.     

Cyclic variations in the differential rotation of the solar corona

The rotation of the solar corona is analyzed using the original database on the brightness of the FeXIV 530.3 nm coronal green line covering six recent activity cycles. The rate of the differential rotation of the corona depends on the cycle phase. In decay phases, there are only small differences in the rotation, which are similar to that of a rigid body. The differences are more significant (though less pronounced than in the photosphere) during rise phases, just before maxima, and sometimes at maxima. The total rate of the coronal rotation is represented as a superposition of two, i.e., fast and slow modes. The synodic period of the fast mode is approximately 27 days at the equator and varies slightly with time. This mode displays weak differences in rotation and is most pronounced in the middle of decay phases. The slow mode is manifested only at high latitudes during the rise phases of activity, and displays a mean period of 31 days. The relative contribution of each mode to the total rotational rate is determined as a function of time and heliographic latitude. These results indicate that the structure of the velocity field in the convective zone must also vary with time. This conclusion can be verified by helioseismology measurements in the near future.     

Systematic compositional variations in the Cape York iron meteorite

Concentrations of Re, Ir and Au are nearly constant within individual masses of the Cape York IIIAB iron meteorite, but differences between masses can be as large as a factor of 2, the extremes being Savik (5.1 μg/g Ir) and Agpalilik (2.7 μg/g Ir). The S concentration shows a still larger range from 13 mg/g in Agpalilik to 1.4 mg/g in Savik. A relatively large compositional hiatus between Dog and Agpalilik probably reflects inadequate sampling of the original material.Concentrations of Ir vary by ~10% and Au by ~3% between the ends of an 85-cm section from the Agpalilik mass of Cape York, but other sections through Agpalilik show smaller variations. These concentration ranges are much larger than expected from radial crystallization of a moderately large (radius 10 s of km) core. These variations in the Agpalilik mass may reflect dendritic crystallization, or they may have resulted from the process that produced the large concentration range among the Cape York masses.Large gradients in Re and Ir and small gradients in Ni and Au were also observed in samples within 2 cm of a large (100 cm³) troilite nodule. These gradients may reflect rapidly changing solid/liquid distribution coefficients during the final crystallization of S-rich liquid.The compositional trends among the various masses can either be explained by mixing of disparate end members followed by diffusive homogenization on a scale of m, or by dendritic crystallization on the ceiling of the IIIAB magma chamber. The mixing of a solid similar in composition to Savik with a liquid in equilibrium with this solid yields a good match to the observed trends, in which case Agpalilik consists of a mixture of 64% liquid and 36% solids. The bulk S content of the IIIAB core is calculated to be 14 mg/g on the basis of this model.     

Oxygen isotope and geochemical variations in the Missouri River

Oxygen isotope ratios in streamflow of the Missouri River basin vary geographically due to differences in source precipitation and the integration of waters from upstream regions. Average '¹⁸O values in the Missouri River main stem systematically increase from less than -17‰ in the headwaters to about -9‰ in the lower basin. Seasonal variations at a given location result from fluctuations in meteoric precipitation, residence time in reservoirs and groundwater systems, evaporation, and snowmelt. Average water chemistry values are successfully predicted for the upstream stations of two reaches on the lower Missouri River based on changes in discharge along each reach and water quality measurements collected at the downstream stations. Source regions for some dissolved ions found in the lower Missouri River are also identified. Sodium and sulfate originate predominantly from the basin above Sioux City, Iowa, while nitrate is largely derived from agricultural regions below Sioux City.     

Compositional variations and reflectance of the common platinum-group minerals

Summary A detailed study of the compositional variations of 22 different platinum-group minerals, of Os-Ir-Ru- and Pt-Fe alloys, Pt-Pd- and Ru-Os-Ir sulfides, RhIr-Pt sulfarsenides and Pd-Pt tellurides from various deposits resulted in verification of extensive solid solution series and element substitution within different mineral groups. On the basis of representative new microprobe analyses and related spectral reflectance curves of the platinum-group minerals investigated significant correlations between chemical composition and reflectance are discussed.

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Chemische Variation und Reflexion der wichtigsten Minerale der Platingruppe

Zusammenfassung Die Untersuchung der chemischen Variation bei 22 Platinmineralen aus der Gruppe der Os-Ir-Ru- und Pt-Fe-Legierungen, Pt-Pd- und Ru-Os-Ir-Sulfide, Rh-Ir-Pt-Sulfarsenide und Pd-Pt-Telluride ergibt signifikante Mischkristallbildung und Element-Substitutionen innerhalb der unterschiedlichen Mineralgruppen. Anhand neuer Mikrosondenanalysen und der zugehörigen spektralen Reflexionskurven der betreffenden Platinminerale werden die Korrelationen zwischen Chemismus und Reflexion diskutiert.

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With 17 Figures

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Contribution to the Ore Mineralogy Symposium (IMA/COM) at the 14th General Meeting of the International Mineralogical Association, at Stanford, California, in July, 1986.