Predictive permeability variations in a Hermod sand reservoir,Stine Segments,Siri Field,Danish North Sea

The Hermod sand of the Stine Segments, Siri Field, Danish North Sea, displays large permeability variations (1–600 mD). These permeability variations represent horizontal layering in the reservoir, largely formed by diagenetic processes. They have a significant impact on reservoir performance, because horizontal producers in fairly thin reservoirs (∼30 m) are protected against bottom-water influx and can produce water-free for long periods of time.     

Glacial history of the Greenland Ice Sheet and a local ice cap in Qaanaaq,northwest Greenland

In this study, we present new information on the glacial history of the Greenland Ice Sheet (GrIS) and a local ice cap in Qaanaaq, northwest Greenland. We use geomorphological mapping, ¹⁰Be exposure dating of boulders, analysis of lake cores, and ¹⁴C dating of reworked marine molluscs and subfossil plants to constrain the glacial history. Our ¹⁴C ages of reworked marine molluscs reveal that the ice extent in the area was at or behind its present‐day position from 42.2 ± 0.4 to 30.6 ± 0.3k cal a BP after which the GrIS expanded to its maximum position during the Last Glacial Maximum. We find evidence of early ice retreat in the deep fjord (Inglefield Bredning) at 11.9 ± 0.6 ka whereas the Taserssuit Valley was deglaciated ~4 ka later at 7.8 ± 0.1k cal a BP. A proglacial lake record suggests that the local ice cap survived the Holocene Thermal Maximum but moss kill‐dates reveal that it was smaller than present for a period of time before 3.3 ± 0.1k until 0.9 ± 0.1k cal a BP, following which the ice in the area expanded towards its Little Ice Age extent. Copyright © 2019 John Wiley & Sons, Ltd.     

Integration of European habitat monitoring based on plant life form composition as an indicator of environmental change and change in biodiversity

Geografisk Tidsskrift, Danish Journal of Geography 106(2): 61–74, 2006

During the last 25 years a number of European countries have developed general landscape monitoring systems. In the agricultural landscapes of Denmark the Small Biotope Monitoring Program (SBMP). which focuses on the dynamics of small biotopes and their relation to changes in agricultural technology and structural characteristics, has been developed since 1981. Erom 2007, the SBMP will continue as part of the Danish nature monitoring program, NOVANA.

In Europe, during the last 10 years, several national landscape surveys have cooperated to develop a European platform for consistent landscape related habitat monitoring. This has been through the BioHab Concerted Action Framework Programme of the EU (2002–2005), and the resulting publication of a handbook for recording and monitoring habitats (Bunce et al., 2005). The focus on environmentally conditioned habitat changes at a landscape level has led to the re-introduction of Raunkiaer's plant life form concept. This approach enables the indication of changes in biodiversity based on alterations in general habitat composition and quality.

Although the objectives of the SBMP and the BioHab projects have been somewhat different, the methodologies have much in common. In this paper the background and perspectives of the two approaches are discussed, and a test of the BioHab field methodology in an area previously monitored by the SBMP is presented. It was found not to be difficult to integrate the BioHab field recording methodology with the existing SBMP methods, thus permitting the SBMP to deliver an additional European perspective, with relatively little additional effort.     

CDM, Feedback and the Hubble Sequence

We have performed TreeSPH simulations of galaxy formation in a standard ΛCDM cosmology, including effects of star formation, energetic stellar feedback processes and a meta-galactic UV field, and obtain a mix of disk, lenticular and elliptical galaxies. The disk galaxies are deficient in angular momentum by only about a factor of two compared to observed disk galaxies. The stellar disks have approximately exponential surface density profiles, and those of the bulges range from exponential to r ^1/4, as observed. The bulge-to-disk ratios of the disk galaxies are consistent with observations and likewise are their integrated B-V colours, which have been calculated using stellar population synthesis techniques. Furthermore, we can match the observed I-band Tully-Fisher (TF) relation, provided that the mass-to-light ratio of disk galaxies is (M/L _I) ≃ 0.6–0.7. The ellipticals and lenticulars have approximately r ^1/4 stellar surface density profiles, are dominated by non-disklike kinematics and flattened due to non-isotropic stellar velocity distributions, again consistent with observations. This revised version was published online in September 2006 with corrections to the Cover Date.     

The mass to light ratio and the initial mass function in galactic discs

A low mass-to-light ratio for the baryonic component of spiral galaxies is advocated by a number of dynamical studies and by cosmological simulations of galaxy formation. We discuss the possibility of obtaining low mass-to-light ratios for the stellar component in discs, by changing the Initial Mass Function and the Star Formation History. This revised version was published online in August 2006 with corrections to the Cover Date.     

Dynamic interpretation of grain size relations in silt

In the salt marsh deposits of the Danish Wadden Sea, a separation has successfully been made of two log-normally distributed grain size populations, which make up the major part of these fine-grained sediments. The coarse population consists almost exclusively of silt and is interpreted as material either deposited as resistant flocs or as single particles. The fine population consists of approximately 50% silt and 50% clay and is interpreted as particles settled as easily destroyable flocs. These interpretations are confirned by the fact that the relative abundance of the two populations is demonstrated to be related to the degree of exposure of salt marsh areas.     

Comparing spatial grain-size trends inferred from textural parameters using percentile statistical parameters and those based on the log-hyperbolic method

The Folk&Ward (F&W) and the log-hyperbolic methods are applied to a small - and easy to overlook - number of typical sand sized grain-size distributions from the Danish Wadden Sea. The sand originates from the same source, and the pattern of change in the grain-size distributions is, therefore, exclusively linked to dynamic sorting. In general, the F&W parameters reflect the observed grain-size trends far better than the corresponding log-hyperbolic parameters. The log-hyperbolic “typical log grain size”, ν, is sensitive to changes in skewness and cannot replace mean grain size, Mz, in grain-size trend analysis. The four log-hyperbolic parameters describing dispersion δ, τ^− 1, κ^− 1 and ζ are not able to give an unambiguous picture of spreading trends. The F&W sorting parameter, Sd, can therefore not be replaced by any of the log-hyperbolic parameters in grain-size trend analysis. In skewed grain-size distributions, there seems to be a general defect in the log-hyperbolic approximation of the best represented tail. This makes χ less sensitive to indicate the correct sign of slightly skewed grain-size distributions than Sk. However, when examining trends, the relative change between χ and Sk by and large seems to be the same. The log-hyperbolic peakedness parameter, ξ, is preferable to the F&W peakedness (kurtosis) parameter, Kg, because the latter is hypersensitive to small, insignificant variations in a grain-size distribution. By contrast, the concept of peakedness as defined by ξ, seems to relate more directly to sedimentary environmental conditions. In conclusion, the log-hyperbolic method has both advantages and disadvantages when compared with the F&W method. It is thus suggested that a sensible combination of the two methods could be advantageous to sediment trend analysis.     

Comparison of Five Eulerian Air Pollution Forecasting Systems for the Summer of 1999 Using the German Ozone Monitoring Data

Eulerian state-of-the-art air pollution forecasting systems on the European scale are operated routinely by several countries in Europe. DWD and FUB, both Germany, NERI, Denmark, NILU, Norway, and SMHI, Sweden, operate some of these systems. To apply such modeling systems, e.g. for regulatory purposes according to new EU directives, an evaluation and comparison of the model systems is fundamental in order to assess their reliability. One step in this direction is presented in this study: The model forecasts from all five systems have been compared to measurements of ground level ozone in Germany. The outstanding point in this investigation is the availability of a huge amount of data – from forecasts by the different model systems and from observations. This allows for a thorough interpretation of the findings and assures the significance of the observed features. Data from more than 300 measurement stations for a 5-month period (May–September 1999) of the German monitoring networks have been used in this comparison. Different spatial and temporal statistical parameters were applied in the evaluation. Generally, it was found that the most comprehensive models gave the best results. However, the less comprehensive and computational cheaper models also produced good results. The extensive comparison made it possible to point out weak points in the different models and to describe the individual model behavior for a full summer period in a climatological sense. The comparison also gave valuable information for an assessment of individual measurement stations and complete monitoring networks in terms of the representativeness of the observation data.     

Impacts of Climate Change on Growth Period and Planting Boundaries of Spring Wheat in China under RCP4.5 Scenario

This article contributes to research on how climate change will impact crops in China by moving from ex-post empirical analysis to forecasting. We construct a multiple regression model, using agricultural observations and meteorological simulations by GCMs, to simulate the possible planting boundaries and suitable planting regions of spring wheat under RCP4.5 scenario for the base period 2040s and 2070s. We find that the south boundary of possible planting region for spring wheat spreads along the belt: south Shandong-north Jiangsu-north Anhui-central Henan-north Hubei-southeast Sichuan-north Yunnan provinces, and will likely move northward under RCP4.5 scenario in 2040s and 2070s, resulting in the decrease of possible planting area in China. Moreover, the sowing and harvest date of spring wheat in the base period shows a gradually delayed phenomenon from the belt: south Xinjiang - Gansu, to the Tibet Plateau. As a result, the growth period of spring wheat in China will shorten because of the impacts of climate change. These results imply that a variety of adaptations measures should be set up in response to changing climatic conditions, including developing the planting base for spring wheat, restricting the planting area of spring wheat in sub-suitable areas at risk while expanding the planting area of optimal crops.