Late Pliocene sand ridges at the western margin of the Barents Sea—do they monitor Late Pliocene glaciations?

Seismic data combined with core analysis of the northwesternmost exploration well on the Norwegian continental margin, well 7316/5-1, has been used to map and discuss the genesis of three well-defined sand ridges. The sand ridges have a NE-SW to N-S orientation and are of Late Pliocene age. The dimensions of the ridges are: height 40 m, length 2–4 km and width 0.5–1 km.In relation to the glaciation models of the Barents Sea, the position of well 7316/5-1, and especially information from a core that penetrated one of the sand ridges, provide important information. The ridges are not, in themselves, diagnostic for grounded glaciers at the margin of the Barents Sea shelf during the Late Pliocene, although the presence of pebbles in a cored section of the ridges may represent ice-dropped material. Whether the possible influx of glaciogenic material is related to local or regional glaciations on the Barents Shelf remains to be evaluated.     

The regional hydrologic impacts of global climate change: the role of climate models

The requirement to increase understanding of the complex interaction between society and the environment is well documented. Dramatic evidence of the vulnerability of anthropogenic systems to short-term weather fluctuations abounds. Taking an historical perspective provides an equally impressive picture of the potential upheaval caused by longer term climate changes. However, the past (and present) may not provide an adequate analoque for the future. The greenhouse theory of climate change suggests that the changes in climate regime to be expected from enhanced atmospheric CO₂ will be of similar magnitude to the glacial-interglacial mean temperature difference, but will occur in a fraction of the time. Consequently, considerable emphasis is being placed on the role of physical climate models in determining projections of future global and regional temperature and precipitation patterns. The latter climate changes will have important implications for the distribution (in time and space) of water, a principal natural resource and basic requirement for a variety of human activities. Consequently, climate models are being applied to the question of determining the regional hydrologic response to global climate change. The latter objective is a prerequisite to assessing the likely impacts on the water resources sector. This paper reviews current progress in achieving this aim and outlines some future research directions.     

Some results of investigations of aurorae and night airglow during the I.G.Y. and I.G.C.

A general review is given of the results of the airglow and auroral investigations during I.G.Y and I.G.C. in the Institute for Atmospheric Physics of the Academy of Sciences of the U.S.S.R. A strong helium emission at 10830 Å has been discovered in sunlit aurorae and in the ordinary twilight airglow. It is now observed regularly. A detailed theory of this fluorescent emission has been developed. Extensive observations on the hydroxyl bands between 5000 and 12,000 Å have been carried out at a number of stations. Marked seasonal and geographical variations have been found in them. During intense aurorae the line-width of the 6300 Å emission from great altitudes increases. The effect has been studied using Fabry-Perot interferometers. Contributions have been made to knowledge on auroral morphology. The interpretation of some of the results which are described in the review are discussed.     

A seasonal climate model of the atmospheres of the giant planets at the voyager encounter time: I. Saturn's stratosphere

A radiative seasonal model which incorporates a multilayer radiative transfer treatment at wave-lengths longward of 7 μm is presented and applied to Saturn's stratosphere. Opacities due to H₂-He, CH₄, C₂H₂, and C₂H₆ are included. Season-dependent insolation is shown to produce a strong hemispheric asymmetry decreasing with depth at the Voyager encounter times, and seasonal amplitudes of 30°K at the poles are predicted in the high stratosphere. The ring-modulated dependence of the insolation and the orbital eccentricity are shown to have a significant effect. Calculations agree closely with the Voyager 1 and 2 radio occultation ingress profiles recorded at 76°S and 36.5°S for CH₄/H₂ = 3.5 + 1.4/? 1.0 × 10^?3;the estimated errors include modeling systematic errors and uncertainties in the occultations profiles. The possible role of aerosols in the stratospheric heating is analyzed. The Voyager 2 egress profile recorded at 31°S cannot be reproduced by calculations. Some constraints on the C₂H₂ and C₂H₆ abundances are derived. The upper portion of the occultation profiles (p < 3mbar) can be matched for C₂H₂/H₂ = 1.0 + 1.3/?0.6 × 10^?7, C₂H₆/H₂ = 1.5 + 1.8/?0.9 × 10^?6 at 76°S and C₂H₂/H₂ = 4 + 6/?4 × 10^?8, C₂H₆/H₂ = 6 + 9/?6 × 10^?7 at 36.5°N. At the northern occultation latitude, the discrepancy with the concentrations derived from analysis of IRIS spectra by R. Courtin, D. Gautier, A. Marten, B. Bézard, and R. Hanel (1984, Astrophys. J.287) can be explained by a sharp variation of the mixing ratios of these gases with altitude in the upper stratosphere. Other interpretations are discussed.     

Accumulation of particulate organic carbon at the Eurasian continental margin during late Quaternary times: controlling mechanisms and paleoenvironmental significance

Data on the amount and composition of organic carbon were determined in sediment cores from the Kara and Laptev Sea continental margin, representing oxygen isotope stages 1–6. The characterization of organic matter is based on hydrogen index (HI) values, n-alkanes and maceral composition, indicating the predominance of terrigenous organic matter through space and time. The variations in the amount and composition of organic carbon are mainly influenced by changes in fluvial sediment supply, Atlantic water inflow, and continental ice sheets. During oxygen isotope stage (OIS) 6, high organic carbon contents in sediments from the Laptev Sea and western East Siberian Sea continental margin were probably caused by the increased glacial erosion and further transport in the eastward-flowing boundary current along the continental margin. During OIS 5 and early OIS 3, some increased amounts of marine organic matter were preserved in sediments east of the Lomonosov Ridge, suggesting an influence of nutrient-rich Pacific waters. During OIS 2, terrigenous organic carbon supply was increased along the Barents and western Kara Sea continental margin caused by extended continental ice sheets in the Barents Sea (Svalbard to Franz Josef Land) area and increased glacial erosion. Along the Laptev Sea continental margin, on the other hand, the supply of terrigenous (organic) matter was significantly reduced due to the lack of major ice sheets and reduced river discharge. Towards the Holocene, the amount of total organic carbon (TOC) increased along the Kara and Laptev Sea continental margin, reaching average values of up to 0.5 g C cm⁻² ky⁻¹. Between about 8 and 10 ka (9 and 11 Cal ka), i.e., during times when the inner shallow Kara and Laptev seas became largely flooded for the first time after the Last Glacial Maximum, maximum supply of terrigenous organic carbon occurred, which is related to an increase in coastal erosion and Siberian river discharge. During the last 8000 years, the increased amount of marine organic carbon preserved in the sediments from the Kara and Laptev Sea continental margin is interpreted as a result of the intensification of Atlantic water inflow along the Eurasian continental margin.     

A method for using a fully coupled climate system model to generate detailed surface boundary conditions for paleoclimate modeling investigations: an early Paleogene example

Although fully coupled models of the earth system are now common, simpler model architectures maintain significant utility, and scientific investigations aimed at understanding paleoclimates are frequently conducted with fixed sea surface temperature (SST) or slab ocean modeling experiments. One of the challenges facing the paleoclimate community is that the proxy data used to generate SST boundary conditions exist at a finer resolution and with very limited spatial coverage when compared to a climate model. In addition, SST proxy estimates often represent a single season or annual average conditions. This mismatch in coverage and resolution frequently results in paleoclimate modelers using SST distributions that have very limited spatial and temporal variability. In many regions, a spatially and temporally detailed SST distribution may be necessary for the accurate reproduction of paleoclimatic conditions. Here we borrow from the concept of flux correction and, using available proxy estimates of SST as our guide, force a fully coupled earth system model to produce a spatially and temporally detailed SST distribution for the paleoclimate of the early Paleogene (45–65 Ma). The SST values we produce represent a conservative estimate of early Paleogene high latitude SSTs and match tropical temperatures for this time period well. In addition to matching proxy estimates, our model-derived SST distribution has spatial and temporal variability that meshes well with global climate model resolution. This detailed SST distribution is now available to us as we investigate the causes and sensitivities of early Paleogene climate in fixed SST and slab ocean modeling experiments. The method we used to generate this spatially and temporally detailed SST distribution may prove useful for those investigating other time periods in the past, or the future, for which detailed model boundary conditions are unavailable.     

The relation between productivity and temperature in the Pliocene North Atlantic at the onset of northern hemisphere glaciation: a palynological study

High resolution palynological analysis of DSDP Cores 607/607A shows for the interval between 2.8 and 2.2 Ma B.P. (which includes the onset of major northern hemisphere glaciations) a 41 ka cyclicity characterised by much higher palynomorph concentrations for the cooler intervals than for the warmer ones. Variation in dilution and concentration of palynomorphs can neither be explained by differential input of terrigenous clastics or carbonate, nor by differences in sedimentation rate, sediment density or selective preservation of palynomorphs. Subdivision of the palynomorph record in terms of autochthonous and allochthonous components, provides a way to detect changes in open ocean productivity and transport through time. It seems that a negative correlation between productivity and temperature in the latest Pleistocene open Atlantic had already been established before the major onset of northern hemisphere glaciations. A conceptual model is proposed to explain the observed lead of the palynological record relative to the isotope and carbonate records is proposed. This early response can result from changes in North Atlantic surface ocean circulation induced by changing atmospheric circulation.     

The thermophob experiment: Direct investigations of the thermophysical properties of the regolith of phobos

The methodology and the main features of the Thermophob experiment developed for the direct analysis of the thermophysical properties of the surface of the Martian satellite Phobos from the Phobos-Grunt lander are considered. The methodical and engineering aspects of the measurements are discussed, and the design of the instrument and the potential of the interpretation of the measurement results with accounting for the theoretical estimates and the data of the laboratory tests are discussed.     

The dependence of the climate sensitivity on convective parametrization: statistical evaluation

Two sensitivity experiments, in which CO₂ is instantaneously doubled, have been performed with a general circulation model to determine the influence of the convective parametrization on simulated climate change. We have examined the spatial structure of changes in the annual mean and annual cycle for surface temperature and precipitation for both experiments; similarly we have examined changes in the variance for these two fields. We have also computed a range of test statistics in order to obtain reliable measures of the signal-to-noise ratio in the climate change signal from each experiment. We have computed test statistics for the entire globe and for five different region and we contrast the global response with the response in the Australian region taken as a representative sample.We find that the highest signal-to-noise ratios in the change from 1 * CO₂ to 2 * CO₂ are for the change in surface temperature for both experiments with little difference in the global averages between the experiments. Globally averaged precipitation shows a greater noise level but perhaps the greatest contrast between experiments. There are generally significant increases in the temporal and spatial variability of precipitation in the change from the 1 * CO₂ to 2 * CO₂ and with some differences apparent between the two experiments. The temporal variability of surface temperature does not change significantly in any of the 2 * CO₂ cases, and there is little difference between the experiments. There is a significant decrease in the spatial variability of surface temperature in all 2 * CO₂ experiments in all cases and with significant differences in the seasonal variations between different experiments. The spatial variability of precipitation increases in all 2 * CO₂ cases and also with substantial differences in the seasonal variations between the experiments. There are accompanying significantly different spatial pattern correlations for both surface temperature and precipitation. In general we find that the global changes are fairly robust with the differences associated with convective parametrization schemes being very small. However, at the regional level, there are marked differences between experiments with changes both in the means and in the spatial and temporal variances but often with low levels of significance.     

Economics, ethics, and climate policy: framing the debate

This paper examines the economic and ethical dimensions of climate policy in light of existing knowledge of the impacts of global warming and the costs of greenhouse gas emissions abatement. We find that the criterion of economic efficiency, operationalized through cost-benefit analysis, is ill-equipped to cope with the pervasive uncertainties and issues of intergenerational fairness that characterize climate change. In contrast, the concept of sustainable development—that today's policies should ensure that future generations enjoy life opportunities undiminished relative to the present—is a normative criterion that explicitly addresses the uncertainties and distributional aspects of global environmental change. If one interprets the sustainability criterion to imply that it is morally wrong to impose catastrophic risks on unborn generations when reducing those risks would not noticeably diminish the quality of life of existing persons, a case can be made for significant steps to reduce greenhouse gas emissions.     

Statistical investigations of the physical properties of radio sources

Six complete samples of radio sources have been analysed by the Spearman rank and the Spearman partial-rank correlation coefficients. The relations between the radio luminosities and linear sizes as well as between linear sizes and redshift indicate that the observed angular diameter-redshift diagram may be explained by the changes of linear sizes with radio luminosity of radio sources.     

Spectroscopic investigations of the magnetic Ap star HD 9996

Spectroscopic measurements of the Ap star HD 9996 yielded the radial velocity and the strength of the effective magnetic field. From the reversal of the magnetic field periods smaller than 4.92 years can be excluded. We cannot state an exact period, but a value of 20.60 years seems to be the most probable one. Further we find hints at a short period of about 1.8 days for the variations in the radial velocities as well as in the magnetic field strengths. The elements of the binary motion were derived.     

Preservation by basalt of a staircase of latest Pliocene terraces of the River Murat in eastern Turkey: Evidence for rapid uplift of the eastern Anatolian Plateau

Unspiked K–Ar dating makes the age of the Çakmaközü basalt in eastern Turkey 1818 ± 39 ka (± 2σ). This basalt overlies a staircase of four terraces of the River Murat, a Euphrates tributary, each separated vertically by  20 m. We deduce from the relationship with the basalt that these fluvial deposits aggraded during successive  40 ka climate cycles around the Pliocene–Pleistocene boundary (probably MIS 72-66). The incision and rock uplift at  0.5 mm a^− 1, thus indicated, are roughly consistent with the  500 m of entrenchment of this  1.8 Ma Murat palaeo-valley into a former lake basin since the Mid-Pliocene climatic optimum. We infer that the  130 m of incision in this locality since  1.8 Ma dramatically underestimates the associated rock uplift, estimated as  600 m. The  1100 m of rock uplift and  800 m of surface uplift thus estimated since the Mid-Pliocene indicate (assuming Airy isostatic equilibrium)  5 km of thickening of the continental crust, from  37 km to the present 42 km. Eastern Anatolia was thus at a much lower altitude in the Mid-Pliocene than at present, consistent with the low-relief lacustrine palaeo-environment. We infer that the subsequent development of topography and excess crustal thickness are being caused by coupling between surface processes and induced flow in the lower crust: climate change following the Mid-Pliocene climatic optimum resulted in faster erosion that has drawn mobile lower crust beneath the study region.     

食双星V375 Cas的光电测光研究

本文给出了首次食双星V375 Cas的BV两色光电测光资料和新的历元,并用Wilson-Devinney综合光变曲线方法取得测光解。结果表明:V375 Cas是一个类似RZ Dra的早型半相接双星系统,小质量子星充满了临界等位面,而大质量子星几乎充满了临界等位面,此星对于了解早型密近双星的演化是很有意义的。     

Spectrophotometric investigations of the blue compact dwarf galaxy Mrk 35

Preliminary results from a detailed spectrophotometric analysis of the blue compact dwarf galaxy (BCD) Mrk 35 are presented. We have performed deep UBVRI broad-band and H_α narrow-band optical observations, near-infrared (JHK _s) imaging and long-slit spectroscopy of the galaxy. Mrk 35 is composed of a very young starburst population distributed in a bar-like structure, placed on top of an underlying, older stellar host galaxy. Using predictions of evolutionary synthesis models, we estimate the ages of both the starburst regions and the underlying stellar component. This revised version was published online in August 2006 with corrections to the Cover Date.     

Sedimentary deposits in Xanthe Terra: Implications for the ancient climate on Mars

A variety of sedimentary deposits is observed in Xanthe Terra, Mars, including Gilbert-type deltas, fan deltas dominated by resedimentation processes, and alluvial fans. Sediments were provided through deeply incised valleys, which were probably incised by both runoff and groundwater sapping. Mass balances based on High-Resolution Stereo Camera (HRSC) digital terrain models show that up to ～30% of the material that was eroded in the valleys is present as deltas or alluvial fan deposits. Stratigraphic relationships and crater counts indicate an age of ～4.0 to ～3.8 Ga for the fluvial activity. Hydrologic modeling indicates that the deposits were probably formed in geologically very short time scales. Our results point to episodes of a warmer and wetter climate on early Mars, followed by a long period of significantly reduced erosion rates.     

Extending the EBM: the effect of deep ocean temperature on climate with applications to the cretaceous

Three types of models are frequently applied to problems of present or past climates: (1) the energy balance model (EBM), which can be solved for the mean thermal state of the climate system based only on thermodynamical considerations, (2) the statistical dynamical model (SDM), which includes momentum considerations from which one can solve for climate statistics on a monthly or seasonal time scale including mean poloidal motions and the hydrologic cycle, and (3) the general circulation model (GCM), which can be solved for the evolving daily weather patterns that are then post-processed to yield all the climate statistics in much the same manner as synoptic data are processed. One major drawback of nearly all these models is that they typically do not consider the subsurface vertical heat fluxes (e.g., the effect of deep ocean temperatures and circulation). We present results froman SDM developed in the late 1960's that includes the parameterized effects of subsurface heat fluxes, and then use these results to demonstrate the importance that deep ocean temperatures can have in determining the climatic state. In this SDM, the ratio of the surface short wave absorption to the surface conductive capacity emerges as a quantity that competes with the subsurface (e.g., deep ocean) temperature in determining surface temperatures. For land, the conductive capacity is small and short wave absorption plays an important role; however, for the ocean the conductive capacity is large and the subsurface (deep ocean) temperature is the dominant influence on the surface temperature for the time scale over which the model is valid. This SDM also includes several of the most important features absent in an EBM, namely, an explicit dependence on the intrinsic physical nature of the earth's surface, the mean poloidal motions in the atmosphere that lead to the climate zonation, and a representation of the hydrologic cycle.When deep ocean temperatures in the model are increased to levels suggested by geologic data for the Cretaceous, surface temperatures at mid to high latitudes become much warmer and the circulation of the atmosphere becomes much subdued, especially as indicated by eddy statistics. These results hold for both present-day and Cretaceous land-ocean distributions, indicating that deep ocean temperature, not geography, is the key model boundary condition. The results also agree with interpretations of geologic data, but disagree in part with earlier interpretations of GCM studies of the Cretaceous. Removal of sea ice (with resultant change from a land-like to an ocean surface) accounts for much of the high latitude warming.