Are Earth Sciences lagging behind in data integration methodologies?     

Hendrik Paasche  Detlef Eberle  Sonali Das  Antony Cooper  Pravesh Debba  Peter Dietrich  Nontembeko Dudeni-Thlone  Cornelia Gläßer  Andrzej Kijko  Andreas Knobloch  Angela Lausch  Uwe Meyer  Ansie Smit  Edgar Stettler  Ulrike Werban 《Environmental Earth Sciences》2014,71(4):1997-2003

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A hydrological tracer experiment with LiCl in a high mountain lake     

Hansjrg Thies  Ulrike Nickus  Christoph Arnold  Roland Psenner 《水文研究》2002,16(12):2329-2337

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Hygroscopic properties of aerosol particles in the north‐eastern Atlantic during ACE‐2     

Erik Swietlicki  Jingchuan Zhou  David S. Covert  Kaarle Hämeri  Bernhard Busch  Minna Väkeva  Ulrike Dusek  Olle H. Berg  Alfred Wiedensohler  Pasi Aalto  Jyrki Mäkelä  Bengt G. Martinsson  Giorgos Papaspiropoulos  Besim Mentes  Göran Frank  Frank Stratmann 《Tellus. Series B, Chemical and physical meteorology》2000,52(2):201-227

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First lacustrine varve chronologies from Mexico: impact of droughts,ENSO and human activity since AD 1840 as recorded in maar sediments from Valle de Santiago   总被引：1，自引：0，他引：1  

Ulrike Kienel  Sabine Wulf Bowen  Roger Byrne  Jungjae Park  Harald Böhnel  Peter Dulski  James F. Luhr  Lee Siebert  Gerald H. Haug  Jörg F. W. Negendank 《Journal of Paleolimnology》2009,42(4):587-609

We present varve chronologies for sediments from two maar lakes in the Valle de Santiago region (Central Mexico): Hoya La Alberca (AD 1852–1973) and Hoya Rincón de Parangueo (AD 1839–1943). These are the first varve chronologies for Mexican lakes. The varved sections were anchored with tephras from Colima (1913) and Paricutín (1943/1944) and ²¹⁰Pb ages. We compare the sequences using the thickness of seasonal laminae and element counts (Al, Si, S, Cl, K, Ti, Mn, Fe, and Sr) determined by micro X-ray fluorescence spectrometry. The formation of the varve sublaminae is attributed to the strongly seasonal climate regime. Limited rainfall and high evaporation rates in winter and spring induce precipitation of carbonates (high Ca, Sr) enriched in ¹³C and ¹⁸O, whereas rainfall in summer increases organic and clastic input (plagioclase, quartz) with high counts of lithogenic elements (K, Al, Ti, and Si). Eolian input of Ti occurs also in the dry season. Moving correlations (5-yr windows) of the Ca and Ti counts show similar development in both sequences until the 1930s. Positive correlations indicate mixing of allochthonous Ti and autochthonous Ca, while negative correlations indicate their separation in sublaminae. Negative excursions in the correlations correspond with historic and reconstructed droughts, El Niño events, and positive SST anomalies. Based on our data, droughts (3–7 year duration) were severe and centred around the following years: the early 1850s, 1865, 1880, 1895, 1905, 1915 and the late 1920s with continuation into the 1930s. The latter dry period brought both lake systems into a critical state making them susceptible to further drying. Groundwater overexploitation due to the expansion of irrigation agriculture in the region after 1940 induced the transition from calcite to aragonite precipitation in Alberca and halite infiltration in Rincón. The proxy data indicate a faster response to increased evaporation for Rincón, the lake with the larger maar dimensions, solar radiation receipt and higher conductivity, whereas the smaller, steeper Alberca maar responded rapidly to increased precipitation.  相似文献   

Halogens in water from the crystalline basement of the Gotthard rail base tunnel (central Alps)   总被引：3，自引：0，他引：3  

Ulrike Seelig 《Geochimica et cosmochimica acta》2010,74(9):2581-2595

Drilling of the new Gotthard rail base tunnel (central Alps) opened a large number of water-conducting fractures in granite and gneiss of the crystalline basement. The overburden reaches locally more than 2000 m and water and rock temperature is up to 45 °C. The tunnel crosses a series of steeply dipping fractured rock units that also crop out at the surface above the tunnel. Recharge water enters the fractured rocks in the high mountainous area, migrates gravity driven to the sampling locality in the tunnel. Along its flow path it reacts with rocks exposed on the fractures where it dissolves the principal granite minerals, resulting in high-pH Na₂CO₃ waters.The tunnel waters contain unusually high concentrations of fluoride ranging from 5 to 29 mg/L. Alteration of F-bearing biotite to F-free chlorite is one of the sources of fluorine. The highest F-concentrations result from the equilibration of low-Ca waters with fluorite. Fluoride concentration is strongly lithology-dependent and sharp discontinuities in both, concentration and saturation state with respect to fluorite occur at the contacts of the different gneiss and granite slabs.Chloride concentrations vary between 1 and 1300 mg/L. In contrast, the Cl/Br mass ratio exhibits small variations and centers around 110 suggesting a common source for the Cl and Br, which is independent of the lithology. In the northern part of the tunnel, Cl and Br are chiefly derived from saline pore fluids of one lithology which is then mixed with low-salinity water along flow paths. Cl/Br ratios of the waters in the southern part of the tunnel section are similar to those measured in experimental leachates from different tunnel rocks, suggesting that leaching of metamorphic fluids in the pore space is the main source of both Cl and Br.  相似文献   

Cyclone life cycle characteristics over the Northern Hemisphere in coupled GCMs   总被引：4，自引：1，他引：3  

Ulrike Löptien  Olga Zolina  Sergey Gulev  Mojib Latif  Vladimir Soloviov 《Climate Dynamics》2008,31(5):507-532

Cyclone activity and life cycle are analysed in the coupled GCMs ECHAM5/OM and ECHAM4/OPYC3. First, the results for the present climate (1978–1999) are compared with ERA-40 and NCEP/NCAR reanalyses, showing a drastic improvement in the representation of cyclone activity in ECHAM5/OM compared to ECHAM4/OPYC3. The total number of cyclones, cyclone intensity, propagation velocity and deepening rates are found to be much more realistic in ECHAM5/OM relative to ECHAM4/OPYC3. Then, changes in extra tropical cyclone characteristics are compared between present day climate and future climate under the emission-scenario A1B using ECHAM5/OM. This comparison is performed using the 20-year time slices 1978–1999, 2070–2090 and 2170–2190, which were considered to be representative for the various climate conditions. The total number of cyclones does not undergo significant changes in a warmer climate. However, regional changes in cyclone numbers and frequencies are evident. One example is the Mediterranean region where the number of cyclones in summer increases almost by factor 2. Some noticeable changes are also found in cyclone life cycle characteristics (deepening rate and propagation velocity). Cyclones in the future climate scenario tend to move slower and their deepening rate becomes stronger, while cyclone intensity does not undergo significant change in a warmer climate. Generally, our results do not support the hypothesis of enhanced storminess under future climate conditions.  相似文献   

Digital mapping in structural geology — Examples from Namibia and Greece     

Cees W. Passchier  Ulrike Exner 《Journal of the Geological Society of India》2010,75(1):32-42

Many problems in geology, especially structural geology, can only be solved by detailed mapping. Presently, mapping is still mainly carried out on paper using techniques from the 19^th Century. However, tools are now available to carry out most mapping tasks on microcomputers in the field without any need of paper. This speeds up geological mapping and reduces the errors involved in the mapping process. Digital mapping also allows work in featureless areas and areas of great structural complexity that would not be possible using paper maps. We present two practical examples of the new technology of digital mapping using microcomputers, from Namibia and Greece.  相似文献   

Late Holocene diatom assemblages in a lake-sediment core from Central Kamchatka,Russia     

Ulrike Hoff  Oleg Dirksen  Veronika Dirksen  Ulrike Herzschuh  Hans-Wolfgang Hubberten  Hanno Meyer  Christel van den Bogaard  Bernhard Diekmann 《Journal of Paleolimnology》2012,47(4):549-560

Fossil diatom assemblages in a sediment core from a small lake in Central Kamchatka (Russia) were used to reconstruct palaeoenvironmental conditions of the late Holocene. The waterbody may be a kettle lake that formed on a moraine of the Two-Yurts Lake Valley, located on the eastern slope of the Central Kamchatka Mountain Chain. At present, it is a seepage lake with no surficial outflow. Fossil diatom assemblages show an almost constant ratio between planktonic and periphytic forms throughout the record. Downcore variations in the relative abundances of diatom species enabled division of the core into four diatom assemblage zones, mainly related to changes in abundances of Aulacoseira subarctica, Stephanodiscus minutulus, and Discostella pseudostelligera and several benthic species. Associated variations in the composition and content of organic matter are consistent with the diatom stratigraphy. The oldest recovered sediments date to about 3220 BC. They lie below a sedimentation hiatus and likely include reworked deposits from nearby Two-Yurts Lake. The initial lake stage between 870 and 400 BC was characterized by acidic shallow-water conditions. Between 400 BC and AD 1400, lacustrine conditions were established, with highest contributions from planktonic diatoms. The interval between AD 1400 and 1900 might reflect summer cooling during the Little Ice Age, indicated by diatoms that prefer strong turbulence, nutrient recycling and cooler summer conditions. The timing of palaeolimnological changes generally fits the pattern of neoglacial cooling during the late Holocene on Kamchatka and in the neighbouring Sea of Okhotsk, mainly driven by the prevailing modes of regional atmospheric circulation.  相似文献   

Single-domain chemical, thermochemical and thermal remanences in a basaltic rock     

Ulrike Draeger  Michel Prévot  Thierry Poidras  Janna Riisager † 《Geophysical Journal International》2006,166(1):12-32

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Physico-chemical and biological sediment properties determining erosion resistance of contaminated riverine sediments – Temporal and vertical pattern at the Lauffen reservoir/River Neckar, Germany     

Sabine Ulrike Gerbersdorf  Thomas Jancke  Bernhard Westrich 《Limnologica》2005,35(3):132-144

In order to contribute to a reliable, easy-to-handle and economically viable erosion risk assessment of contaminated riverine sites, the present study aims to implement master-variables best characterising the sediment stability. Thus, a wide range of sediment properties was related to the critical shear stress for mass erosion, determined in the SETEG (Stroemungskanal zur Ermittlung der tiefenabhaengigen Erosionsstabilitaet von Gewaessersedimenten) pressurised channel, with special emphasis on vertical and temporal gradients in the Lauffen reservoir on the River Neckar. Over the course of 1 year, positive impacts of some macrofauna species and benthic diatoms on the sediment stability were detected for the sediment surface (0.5 cm). However, a high seasonal variability of biological parameters caused varying relations with erosion resistance in the upper sediment layers as shown for the colloidal carbohydrates. Considering only deeper sediment layers (5–35 cm), a more general pattern could be revealed with correlations between the critical shear stress and single sediment properties such as depth, grain size, total organic carbon (TOC), cation exchange coefficient (CEC), carbohydrates and proteins. Firstly, the influence of physico-chemical and biological properties on erosion resistance became evident, even over depths at 0–35 cm. Secondly, inter-particle forces are most important for erosion resistance. These are enhanced in fine-grained sediment layers, offering high binding capacities but also strengthened by polymeric substances permeating the void space and coating particles. These covariance patterns of sedimentological and biological parameters are addressed by multivariate statistical tests (principal component analysis), resulting in a higher magnitude of the correlation coefficient between critical shear stress and the master-variables in main component II (polymeric substances, grain size, TOC, CEC; R=0.77) compared to single correlations.  相似文献