Climatic change as a topic in the classical Greek and Roman literature     

J. Neumann 《Climatic change》1985,7(4):441-454

A search was made of the classical Greek and Roman literature for references to climatic change, irrespective whether facts of observation or views. It was found that several scholars/scientists of the classical antiquity made pronouncements on the subject and their statements are either summarized or quoted verbatim in this paper. From the Greek literature we quote Plato, Aristotle and Theophrastus; Herodotus is also quoted for an indirect reference to the topic. From the Roman literature we cite the agricultural writer Columella and the scientist Pliny the Elder; actually, Columella quotes the distinguished writers on husbandry, the Sasernas, father and son.Aristotle's statement is relevant to a degree to the Mycenaean drought (~ 1200 B.C.) problem. The Columella-Saserna pronouncement relates to the astronomical theory of climatic change, while Theophrastus discusses man-made climatic changes.Appendix I gives a statistics of storms, as gleaned from the classical literature, covering approximately the months April–October. Further, it lists some pointers to the relative coolness of the era 850/800–400/300 B.C. in some areas of the Mediterranean. Appendix II offers a few examples for the usefulness of the ancient literature from the point of view of environmental data or events.Now visiting with the Department of Meteorology, The University of Helsinki, Helsinki, Finland.  相似文献   

Subsurface countercurrent in the Bosporus already known to 6th century A. D. Byzantine fishermen     

Prof. Dr. Manfred Korfmann  Prof. Dr. Jehuda Neumann 《Ocean Dynamics》1985,38(4):189-190

  相似文献   

Meteorites from the asteroid 6 Hebe     

Paolo Farinella  Christiane Froeschlé  Robert Gonczi 《Celestial Mechanics and Dynamical Astronomy》1993,56(1-2):287-305

We have numerically integrated the orbits of 18 fictitious fragments ejected from the asteroid 6 Hebe, an S-type object about 200km across which is located very close to theg=g ₆ (orv ₆) secular resonance at a semimajor axis of 2.425AU and a (proper) inclination of 15° .0. A realistic ejection velocity distribution, with most fragments escaping at relative speeds of a few hundredsm/s, has been assumed. In four cases we have found that the resonance pumps up the orbital eccentricity of the fragments to values >0.6, which result into Earth-crossing, within a time span of 1Myr; subsequent close encounters with the Earth cause strongly chaotic orbital evolution. The closest Earth and Mars encounters recorded in our integration occur at miss distances of a few thousandths ofAU, implying collision lifetimes <10⁹ yr. Some other fragments affected by the secular resonance become Mars-crossers but not Earth-crossers over the integration time span. Two bodies are injected into the 3 : 1 mean motion resonance with Jupiter, and also display macroscopically chaotic behaviour leading to Earth-crossing. 6 Hebe is the first asteroid for which a realistic collisional/dynamical evolutionroute to generate meteorites has been fully demonstrated. It may be the parent body of one of the ordinary chondrite classes.  相似文献   

A comparison of bowen ratio and eddy correlation sensible and latent heat flux measurements above deciduous forest     

Alan G. Barr  K. M. King  T. J. Gillespie  G. Den Hartog  H. H. Neumann 《Boundary-Layer Meteorology》1994,71(1-2):21-41

Sensible and latent heat flux densities (H and E) were measured above a mature, 18 m deciduous forest during July and August, 1988, using the Bowen ratio-energy balance (BREB) and eddy correlation (EC) methods. EC estimates ofH and E underestimated day-time surface available energy by 11%. EC also partitioned available energy differently than BREB. for/L<0.0, EC favouredH and BREB favoured E. Practical and theoretical limitations of the BREB and EC methods above forests are discussed. The most plausible causes for the failure of EC to close the surface energy balance are a low frequency loss of flux and the failure of a single point measurement to account for the spatial dispersive flux. The most plausible causes of the EC-BREB energy partitioning anomaly are the invalidity of the BREB similarity assumption and the violation of flux-gradient diffusion assumptions in the near-field diffusion region.  相似文献   

Early diagenetic processes during Mn-carbonate formation: evidence from the isotopic composition of authigenic Ca-rhodochrosites of the Baltic Sea   总被引：1，自引：0，他引：1  

Thomas Neumann  Uwe HeiserMarkus A Leosson  Michael Kersten 《Geochimica et cosmochimica acta》2002,66(5):867-879

The formation of authigenic Ca-rich rhodochrosite (ACR) in sapropelic sediments of the Gotland Basin, Baltic Sea, is governed by deepwater renewal processes whereby saline water from the North Atlantic flushes the brackish anoxic Baltic Deeps. The carbon and oxygen isotopic compositions of these Mn-carbonates suggest that ACR formation takes place just below the sediment surface and that dissolved compounds from the deepwater column, such as water and bicarbonate molecules, were incorporated in ACR during authigenesis. Porewaters near the sediment surface display δ¹⁸O values of −5.4‰ (VSMOW) and are generally depleted in ¹⁸O, compared to the oxygen isotopic composition of water in equilibrium with Mn-carbonate solid solutions (ACR δ¹⁸O values are −4.6‰). This suggests that early burial diagenetic processes significantly modify the initial isotopic composition of water during Mn-carbonate formation. The reduction of sulfate having δ¹⁸O values of +8.4‰ accounts for a permanent enrichment of porewater ¹⁸O and observed δ¹⁸O values at depth equal to −4.6‰. However, this process does not explain the observed disequilibrium in the oxygen isotopic composition between water and ACR close to the sediment surface where Mn-carbonate formation takes place. Based on isotopic mass balance calculations, we suggest that MnO₂ with δ¹⁸O values of +8.9‰ released oxygen enriched in ¹⁸O into the anoxic porewaters close below the sediment surface. This process should occur after oxygenation events during deepwater renewal when MnO₂ accumulates at the surface of anoxic sediments. Manganese carbonates formed in these waters display δ¹⁸O values of ∼1.0‰ heavier than values expected solely from the initial deepwater composition. This quantitatively explains the discrepancy between paleosalinities calculated from ACR δ¹⁸O based on Mn-carbonate/water isotopic equilibrium fractionation and direct observations for the same period. Our results emphasize the important role of microbial MnO₂ reduction during rhodochrosite authigenesis and suggest that Mn(II) activity, rather than alkalinity, is the limiting component for sedimentary Mn-carbonate formation.  相似文献   

Comparative assessment of CORINE2000 and GLC2000: Spatial analysis of land cover data for Europe   总被引：3，自引：0，他引：3  

K. Neumann  M. Herold  A. Hartley  C. Schmullius   《International Journal of Applied Earth Observation and Geoinformation》2007,9(4):425-437

Given the current lack of interoperability between global and regional land cover products, efforts are underway to link the new European global land cover map (GLOBCOVER) with the existing global land cover 2000 map (GLC2000) and European CORINE mapping initiative. Since both datasets apply different mapping standards, key for a successful implementation is a thorough understanding of the heterogeneities among both datasets. Thus, this paper provides an assessment of compatibilities and differences between the CORINE2000 and GLC2000 datasets. The comparative assessment considers inconsistencies between the thematic legends (using the UN land cover classification system-LCCS), class specific accuracies, and the spatial resolution and heterogeneity of the datasets. The results are summarized with implications for the development of the new GLOBCOVER datasets.  相似文献   

Application of Gibbs Energy Minimization to ModelEarly-Diagenetic Solid-Solution Aqueous-Solution EquilibriaInvolving Authigenic Rhodochrosites in Anoxic BalticSea Sediments     

Dmitrii A. Kulik  Michael Kersten  Uwe Heiser  Thomas Neumann 《Aquatic Geochemistry》2000,6(2):147-199

The natural early-diagenetic environment ``anoxicporewater – authigenic mineral phases' has beencharacterized in sediment of the Gotland Deep,Baltic Sea, by a closed-system model. Occurrence ofcarbonate precipitates as thin almost pure whitelaminae was considered as a natural experiment forlong-term equilibration between these phases andporewater. Plots of distribution coefficientsindicate that metastable equilibrium exists betweenporewater and the authigenic Ca-rich rhodochrositephases below 7 cm depth. A thermodynamic model ofporewater geochemistry at in situ P = 25 barand T = 5 °C was developed using the Gibbsenergy minimization (GEM) approach. The values of isobaric-isothermal potentials of Mn, Ca, Fe, Mg,Sr, Ba, C, and O, calculated from the porewatercomposition, were used in a new ``dual thermodynamic'calculation approach to estimate solid activitycoefficients of the end-members in the non-idealsolid solution (Mn, Ca, Mg, Sr, Ba, Fe)CO₃,i.e., at full major and minor multi-componentcomplexity. The regular Margules interactionparameters for the composing binaries estimated bythis model were _Mn-Ca = 1.9 ± 0.5,_Mn-Mg = 0.6,_Ca-Mg = 3.7,_Mn-Fe = 0.2,_Ca-Fe = 2.8,_Mn-Sr = 9.7,_Ca-Sr = 2.15,_Mn-Ba = 4.0,_Ca-Ba = 1.4,validating the theoretical predictions given byLippmann in his pioneering 1980's paper. Thestrictly thermodynamic equilibrium model is not onlyable to match both the measured porewater andcarbonate solid-solution composition, but also topredict that the porewater pH, pe, alkalinity, anddissolved Mn, Fe, and S concentrations arecontrolled by the authigenic mineral bufferingassemblage mackinawite-greigite-rhodochrosite. Ourmodel is only compatible with the idea of ACRformation with typical composition (X_Mnbetween 70–75%) in the topmost sediment layerwhich, however, needs a major source ofMn_aq ^II. This is provided by reduction ofparticulate Mn oxides precipitated in significantamounts in the water column upon major inflow eventsin the Baltic Sea. The model enables also to set upscenarios of changing environmental conditions, e.g.,to predict the non-linear response of the carbonatesolid-solution composition to changes in Mn loading,alkalinity and salinity of the sediment-watersystem. The results suggest that the major andespecially minor element contents (Sr, Mg, Ba) inauthigenic carbonates can be applied as anenvironmental paleoproxy.  相似文献   

The Chemical Evolution of the Universe on its Smallest Scales: Dust in Stars,Disks and Planets     

Christiane Helling  Jane Greaves  Anja C. Andersen 《Astronomische Nachrichten》2007,328(7):645-660

D15 Dust and gas in the inner accretion disk around the Herbig star MWC 147 resolved with infrared spectro‐interferometry D21 The effective temperature of OGLE‐TR‐10 – The Balmer α line D29 Metal Injection into the Intracluster Medium D30 Eigenmodes of circumstellar dust shells D40 Numerical Modelling Approach of Circumstellar Dust Shells Around Pulsating AGB Stars Aiming at Multi Time Scale Processes D45 UV radiation induced CO molecule formation patterns in low density PDRs D46 IR properties of calcite and dolomite at low temperatures D47 Observations and Models of Dusty Giants – Past and Present D51 A multi‐method approach to the outer layers of AGB stars D53 On the convective energy transport in M‐type brown dwarf atmospheres D70 Structure and Dust Composition of the TW Hya Disc D75 Chemical Abundances in the Carina Dwarf Spheroidal Galaxy D76 Kinematic and chemical constraints on the formation of M31's inner halo structures D77 IR band profiles of silicate and oxide dust obtained by laboratory measurements of free‐flying particles D98 Dust particle growth in protoplanetary disks D134 Comparative study of dust cloud modelling for substellar atmospheres D137 Photometric study of neglected binary DV Psc D154 Quantitative Spectroscopy of Deneb D160 Hot subluminous Ostars from the SDSS D166 Simultaneous Observations of Solar Ca II H and Ca II 8662 lines and Numerical Simulation of these lines D182 Present‐day carbon abundances in the solar vicinity D189 Detection of a giant planet around a pulsating extreme horizontal branch star: the oldest known planet? D200 Confirmation of a very young binary brown dwarf candidate with disk in Chamaeleon D208 Galaxy ages and metallicities in the cluster A1314 D217 Charge‐dipole induced dust gelation – fastening the process of dust growth in protoplanetary disks D246 Protoplanetary Disk Structure and Evolution  相似文献   

Formation of Brown Dwarfs and Planets: Observations,Experiments and Theory     

Günther Wuchterl  Eike Günther  Christiane Helling 《Astronomische Nachrichten》2005,326(7):625-633

I01 NIR Imaging Spectroscopy of Extrasolar Planets I02 Eccentricity growth in protoplanetary disks with embedded planets I03 Brown dwarf atmospheres: the dust in the L – T transition region I04 Model Atmospheres of Substellar Atmospheres at a Young Age:Influence of Gravity and Dust I05 Detection of Planetary Transits using Wavelet Analysis and Genetic Algorithms I06 Automated Difference Imaging for Extrasolar Planet Searches I07 The formation of planets around stars with various masses I08 The Multiplicity of exoplanet host stars I09 Direct imaging of planets around young stars, the case of GQ Lup b I10 On the Nucleation of NH₃ under the Atmospheric Conditions of Jovian‐like Planets I11 Unveiling a new low‐mass star formation site in NGC 1333 with SCUBA I12 Linear analysis of the stability of protoplanets: Possible planetary evolutions and comparisons to the Jeans‐analysis I13 Triggered planet formation in young stellar clusters I14 Convective Radiation Fluid‐Dynamics: Formation and Early Evolution at the Substellar Limit and Beyond  相似文献   

Microplastics in oceans     

Zarfl C  Fleet D  Fries E  Galgani F  Gerdts G  Hanke G  Matthies M 《Marine pollution bulletin》2011,62(8):1589-1591

  相似文献