International viewpoint and news     

Karsten Gohl  Alan Haywood 《Environmental Geology》2009,56(6):1249-1250

  相似文献   

Long term variations of extreme rainfall in Denmark and southern Sweden     

Ida Bülow Gregersen  Henrik Madsen  Dan Rosbjerg  Karsten Arnbjerg-Nielsen 《Climate Dynamics》2015,44(11-12):3155-3169

  相似文献   

Estimation of regional evapotranspiration over the North China Plain using geostationary satellite data     

Yunqiao Shu  Simon Stisen  Karsten H. Jensen  Inge Sandholt 《International Journal of Applied Earth Observation and Geoinformation》2011

Data from the first operational Chinese geostationary satellite Fengyun-2C (FY-2C) satellite are applied in combination with Moderate Resolution Imaging Spectroradiometer (MODIS) satellite products for the assessment of regional evapotranspiration over the North China Plain. The approach is based on the improved triangle method, where the temperature–vegetation index space includes thermal inertia. Two thermal infrared channels from FY-2C are used to estimate surface temperature (Ts) based on a split window algorithm originally proposed for the MSG-SEVIRI sensor. Subsequently the high temporal resolution of FY-2C data is exploited to give the morning rise in Ts. Combined with the 16 days composite MODIS vegetation indices product (MOD13) at a spatial resolution of 5 km, evaporative fraction (EF) is estimated by interpolation in the ΔTs–NDVI triangular-shaped scatter space. Finally, regional actual evapotranspiration (ET) is derived from the evaporative fraction and available energy estimated from MODIS surface albedo products MCD43. Spatial variations of estimated surface variables (Ts, EF and ET) corresponded well to land cover patterns and farmland management practices. Estimated ET and EF also compared well to lysimeter data collected for the period June 2005–September 2007. The improved triangle method was also applied to MODIS products for comparison. Estimates based on FY-2C products proved to provide slightly better results than those based on MODIS products. The consistency of the estimated spatial variation with other spatial data supports the use of FY-2C data for ET estimation using the improved triangle method. Of particular value is the high temporal frequency of image acquisitions from FY-2C which improves the likelihood of obtaining cloud free image acquisitions as compared to polar orbiting sensors like MODIS.  相似文献   

Invasion genetics of Pacific oyster Crassostrea gigas shaped by aquaculture stocking practices     

Jenny Moehler  K. Mathias Wegner  Karsten Reise  Sabine Jacobsen 《Journal of Sea Research》2011,66(3):256-262

As a result of aquaculture activities Pacific oysters Crassostrea gigas (Thunberg, 1793) have invaded the European Wadden Sea. Using a variable noncoding mitochondrial marker, we show that the invaded range is the result of two independent invasions. Haplotype frequencies point towards two separate groups, one in the southern and the other in the northern Wadden Sea. We found virtually no genetic differentiation throughout the southern range and the putative source from British Columbia, Canada, suggesting that the Southern region can be considered as a closed population. In the North, mismatch distributions, haplotype ordination and isolation-by-distance analysis suggest a stronger, persistent impact of aquaculture on invasive populations. Due to the ongoing supply of new genetic material from hatchery production the northern invasive populations can therefore be considered as an open population highlighting the importance of aquaculture practice on the genetics of this keystone invader in the Wadden Sea.  相似文献   

Measuring Thermo-Mechanical Properties of Cometary Surfaces: In Situ Methods     

Kömle  Norbert I.  Kargl  Günter  Seiferlin  Karsten  Marczewski  Wojiech 《Earth, Moon, and Planets》2002,90(1-4):269-282

Thermal and mechanical properties of cometary ices are closely associated with eachother. Both are largely determined by the texture (porosity, grain size distribution,grade of sintering) of the material. The surface probe of the Rosetta mission to comet46P/Wirtanen (Rosetta Lander) will for the first time measure these thermo-mechanical keyparameters in situ, using a hammering device, a drill, and anchors to be shot intothe ground by pyrotechnical means. Several of these components are associated to theexperiment MUPUS (MUlti-PUrpose-Sensors forsurface and sub-surface science). The development of this instrument has now reached amature state, as the flight model is already delivered and integrated with thespacecraft. We describe the main aspects of the experiment, outline the evaluationmethods, and show representative results from test measurements.  相似文献   

Nitrate reduction potential of a fractured Middle Triassic carbonate aquifer in Southwest Germany     

Osenbr&#;ck  Karsten  Blendinger  Eva  Leven  Carsten  R&#;gner  Hermann  Finkel  Michael  Jakus  Natalia  Schulz  Hartmut  Grathwohl  Peter 《Hydrogeology Journal》2022,30(1):163-180

Hydrogeology Journal - Nitrate reduction constitutes an important natural mechanism to mitigate the widespread and persistent nitrate contamination of groundwater resources. In fractured aquifers,...  相似文献   

Textural evolution of perovskite in the Afrikanda alkaline–ultramafic complex,Kola Peninsula,Russia     

Naomi?J.?PotterEmail author  Matthew?R.?M.?Ferguson  Vadim?S.?Kamenetsky  Anton?R.?Chakhmouradian  Victor?V.?Sharygin  Jay?M.?Thompson  Karsten?Goemann 《Contributions to Mineralogy and Petrology》2018,173(12):100

Perovskite is a common accessory mineral in a variety of mafic and ultramafic rocks, but perovskite deposits are rare and studies of perovskite ore deposits are correspondingly scarce. Perovskite is a key rock-forming mineral and reaches exceptionally high concentrations in olivinites, diverse clinopyroxenites and silicocarbonatites in the Afrikanda alkaline–ultramafic complex (Kola Peninsula, NW Russia). Across these lithologies, we classify perovskite into three types (T1–T3) based on crystal morphology, inclusion abundance, composition, and zonation. Perovskite in olivinites and some clinopyroxenites is represented by fine-grained, equigranular, monomineralic clusters and networks (T1). In contrast, perovskite in other clinopyroxenites and some silicocarbonatites has fine- to coarse-grained interlocked (T2) and massive (T3) textures. Electron backscatter diffraction reveals that some T1 and T2 perovskite grains in the olivinites and clinopyroxenites are composed of multiple subgrains and may represent stages of crystal rotation, coalescence and amalgamation. We propose that in the olivinites and clinopyroxenites, these processes result in the transformation of clusters and networks of fine-grained perovskite crystals (T1) to mosaics of more coarse-grained (T2) and massive perovskite (T3). This interpretation suggests that sub-solidus processes can lead to the development of coarse-grained and massive perovskite. A combination of characteristic features identified in the Afrikanda perovskite (equigranular crystal mosaics, interlocked irregular-shaped grains, and massive zones) is observed in other oxide ore deposits, particularly in layered intrusions of chromitites and intrusion-hosted magnetite deposits and suggests that the same amalgamation processes may be responsible for some of the coarse-grained and massive textures observed in oxide deposits worldwide.  相似文献   

Early Eocene volcanic ashes on Greifswalder Oie and their depositional environment,with an overview of coeval ash-bearing deposits in northern Germany and Denmark     

Karsten Obst  Jörg Ansorge  Sabine Matting  Heiko Hüneke 《International Journal of Earth Sciences》2015,104(8):2179-2212

  相似文献   

Rift processes and crustal structure of the Amundsen Sea Embayment,West Antarctica,from 3D potential field modelling     

Thomas Kalberg  Karsten Gohl  Graeme Eagles  Cornelia Spiegel 《Marine Geophysical Researches》2015,36(4):263-279

  相似文献   

A three-dimensional model study on processes of stratification and de-stratification in the Limfjord     

Richard Hofmeister  Hans Burchard  Karsten Bolding 《Continental Shelf Research》2009,29(11-12):1515-1524

Investigations on stratifying and de-stratifying processes in the Limfjord in Denmark, stretching from the North Sea at the western end to the Kattegat at the eastern end, were carried out. The forcing of the Limfjord is dominated by mean sea surface elevation and salinity gradients, diffuse freshwater supply, as well as episodic saline inflow events from the North Sea boundary. The physical regime of the Limfjord switches periodically from stratified to mixed conditions. In order to investigate the complexity of the system, a realistic three-dimensional high-resolution numerical model study was conducted for the year 2003. The results are based on, and compared to, available field data. A central subject of this study is the anomaly of potential energy as a measure for stratification. The stratifying and de-stratifying processes are identified as contributing terms in a dynamic equation for the potential energy anomaly. The comparison of model results and observations shows that the model has the capability of reproducing the observed physical regimes. Changes in the simulated stratification turn out to be a complex interaction of differential advection, heating and turbulent mixing in the central Limfjord.  相似文献