Potential effects of navigation-induced wave wash on the early life history stages of riverine fish     

Verena Kucera-Hirzinger  Elisabeth Schludermann  Horst Zornig  Anton Weissenbacher  Michael Schabuss  Friedrich Schiemer 《Aquatic Sciences - Research Across Boundaries》2009,71(1):94-102

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Effect of enhanced water exchange on ecosystem functions in backwaters of an urban floodplain     

Elisabeth Bondar-Kunze  Stefan Preiner  Friedrich Schiemer  Gabriele Weigelhofer  Thomas Hein 《Aquatic Sciences - Research Across Boundaries》2009,71(4):437-447

This study evaluated the effects of a controlled surface water connectivity scheme on several backwaters in an urban floodplain within the city limits of Vienna, the Upper Lobau. A phosphorus budget and ecosystem metabolism measurements were used to assess the reaction of two trophically distinct floodplain backwater sections on changed connectivity conditions. The surface water connection led to a reduction of the retention times in the backwater system. The water column nutrient concentrations in the individual backwater sections approached those of the source water body. The significance of these effects, however, depends on the historical and current trophic situation of the respective water bodies. Generally, the surface water connectivity introduced particulate phosphorus export up to 30% increase over the influent loading and dissolved phosphorus up to 14% increase over the influent loading. However, in sections with submersed macrophyte development, which provided enhanced filtering capacities for particulate matter, sediment and phosphorus accumulation rates were increased. At the same time, water transparency increased resulting in a positive feedback supporting further macrophyte development. Based on these findings, the evaluation of restoration measures in urban floodplains needs to consider the spatial and temporal dynamics of nutrients and ecosystem processes such as gross primary production and community respiration to predict long-term development.  相似文献   

Numerical investigations of the turbulent kinetic energy dissipation rate in the Rhine region of freshwater influence     

Elisabeth Fischer  Hans Burchard  Robert D. Hetland 《Ocean Dynamics》2009,59(5):629-641

The turbulent kinetic energy dissipation rate, ε, in tidal seas is maximum at the bottom during full flood and during full ebb, i.e. when tidal currents are strongest. In coastal regions with tides similar to a Kelvin wave, this coincides with high water and low water. If there is a freshwater source at the coast, stratification in such a region will be most stable at high water and least at low water. Measurements of ε in the Rhine region of freshwater influence performed by previous studies have revealed bottom maxima at both high and low water. In addition, a maximum in the upper half of the water column was found around high water, which cannot be explained by tidal shear at the bottom, convective instabilities or wind mixing. This study investigates the dissipation rate and relevant physical properties in the Rhine region of freshwater influence by means of three-dimensional numerical simulations using the General Estuarine Transport Model and idealised conditions. The measurements are well reproduced; two distinct peaks of ε are evident in the upper layer shortly before and after high water. These maxima turn out to be due to strong peaks in the alongshore shear occurring when the fore- and the back-front of the plume transit the water column.  相似文献   

On the (im-)possibilities of defining human climate thresholds     

Elisabeth Meze-Hausken 《Climatic change》2008,89(3-4):299-324

The aim of this study is to explore the way climate creates thresholds within society. Both human physiology and the human mind determine when and where climate can trigger and influence human activities. By presenting a stimulus-response model, deliberate weather- and climate- related decisions (e.g. migration, clothing) and physiological responses in daily life (e.g. sweating) are placed in a broader theoretical context. While physiological thresholds can be described quantitatively to a certain extent, subjective thresholds may be illustrated in a predominantly qualitative manner through surrogates (surveys on wants or needs). Examples from the literature on climate thresholds for humans highlight the complexity of the issue: People have different thresholds, as they do not necessarily respond to the same stimuli in the same way. At the same time, given the same stimulus, an individual may perceive it, and thus react, differently at different times in their life. In many cases, the threshold rather specifies a bandwidth or transition zone than a particular point. The level of acceptance and the cultural, technological and genetic aspects of adaptation will decide how climate may influence human well-being and contribute in setting limits to society, for example where to live, what impacts to expect, and when and what decisions to take. Knowledge of the complexity of human thresholds can be an important supplement to the analysis of peoples’ vulnerability to climate change. When populations are vulnerable and thresholds are exceeded, only then will there be a measurable response.  相似文献   

Use of total precipitable water classification of a priori error and quality control in atmospheric temperature and water vapor sounding retrieval     

Eun-Han KWON  Jinlong LI  B. J. SOHN  Elisabeth WEISZ 《大气科学进展》2012,29(2):263-273

This study investigates the use of dynamic a priori error information according to atmospheric moistness and the use of quality controls in temperature and water vapor profile retrievals from hyperspectral infrared (IR) sounders. Temperature and water vapor profiles are retrieved from Atmospheric InfraRed Sounder (AIRS) radiance measurements by applying a physical iterative method using regression retrieval as the first guess. Based on the dependency of first-guess errors on the degree of atmospheric moistness, the a priori first-guess errors classified by total precipitable water (TPW) are applied in the AIRS physical retrieval procedure. Compared to the retrieval results from a fixed a priori error, boundary layer moisture retrievals appear to be improved via TPW classification of a priori first-guess errors. Six quality control (QC) tests, which check non-converged or bad retrievals, large residuals, high terrain and desert areas, and large temperature and moisture deviations from the first guess regression retrieval, are also applied in the AIRS physical retrievals. Significantly large errors are found for the retrievals rejected by these six QCs, and the retrieval errors are substantially reduced via QC over land, which suggest the usefulness and high impact of the QCs, especially over land. In conclusion, the use of dynamic a priori error information according to atmospheric moistness, and the use of appropriate QCs dealing with the geographical information and the deviation from the first-guess as well as the conventional inverse performance are suggested to improve temperature and moisture retrievals and their applications.  相似文献   

Evaluation of stable iodine status of the areas affected by the Chernobyl accident in an epidemiological study in Belarus and the Russian Federation     

Elena Korobova  Yadviga Anoshko  Ausrele Kesminiene  Aleksander Kouvyline  Sergei Romanov  Vanessa Tenet  Eero Suonio  Elisabeth Cardis 《Journal of Geochemical Exploration》2010

Variation of the stable iodine supply was evaluated in the soils of around more than 700 settlements in the regions (oblasts) of Belarus and the Russian Federation contaminated after the Chernobyl accident. It involved the use of regional information on iodine content in different types of soil cover, biogeochemical criteria of iodine deficiency in food chains, and the available soil maps.  相似文献   

Lithostratigraphic and structural controls of ‘tsavorite’ deposits at Lemshuku,Merelani area,Tanzania     

Julien Feneyrol  Gaston Giuliani  Daniel Ohnenstetter  Elisabeth Le Goff  Elias P.J. Malisa  Mark Saul  Eric Saul  John Saul  Vincent Pardieu 《Comptes Rendus Geoscience》2010,342(10):778-785

The first study of the Lemshuku ‘tsavorite’ mining district is presented. From bottom to top, the lithostratigraphic column corresponds to a metasedimentary sequence composed of quartzite, fine-grained graphitic gneiss, kyanite-graphite gneiss, biotite-almandine gneiss, metasomatized graphitic gneiss and dolomitic marble. ‘Tsavorite’ occurs in quartz veins and rarely as nodular concretions. Two factors control mineralization: (1) lithostratigraphy, with ‘tsavorite’ in association with pyrite and graphite confined to quartz veins within the metasomatized graphitic gneiss; and (2) structure, with the mineralized veins characteristically controlled by tight isoclinal folds associated with shearing.  相似文献   

Consistent past half-century trends in the atmosphere, the sea ice and the ocean at high southern latitudes     

Hugues Goosse  Wouter Lefebvre  Anne de Montety  Elisabeth Crespin  Alejandro H. Orsi 《Climate Dynamics》2009,33(7-8):999-1016

Simulations performed with the climate model LOVECLIM, aided with a simple data assimilation technique that forces a close matching of simulated and observed surface temperature variations, are able to reasonably reproduce the observed changes in the lower atmosphere, sea ice and ocean during the second half of the twentieth century. Although the simulated ice area slightly increases over the period 1980–2000, in agreement with observations, it decreases by 0.5 × 10⁶ km² between early 1960s and early 1980s. No direct and reliable sea ice observations are available to firmly confirm this simulated decrease, but it is consistent with the data used to constrain model evolution as well as with additional independent data in both the atmosphere and the ocean. The simulated reduction of the ice area between the early 1960s and early 1980s is similar to the one simulated over that period as a response to the increase in greenhouse gas concentrations in the atmosphere while the increase in ice area over the last decades of the twentieth century is likely due to changes in atmospheric circulation. However, the exact contribution of external forcing and internal variability in the recent changes cannot be precisely estimated from our results. Our simulations also reproduce the observed oceanic subsurface warming north of the continental shelf of the Ross Sea and the salinity decrease on the Ross Sea continental shelf. Parts of those changes are likely related to the response of the system to the external forcing. Modifications in the wind pattern, influencing the ice production/melting rates, also play a role in the simulated surface salinity decrease.  相似文献   

Mapping the vulnerability of crop production to drought in Ghana using rainfall, yield and socioeconomic data     

Philip Antwi-Agyei  Evan D.G. Fraser  Andrew J. DougillLindsay C. Stringer  Elisabeth Simelton 《Applied geography (Sevenoaks, England)》2012,32(2):324-334

This study evaluates new multi-scale, multi-indicator methods for assessing the vulnerability of crop production to drought at a national and regional scale. It does this by identifying differences across and within ten regions of Ghana, a country that faces many climate and crop production challenges typical of sub-Saharan Africa. In particular, we illustrate how a quantitative national and regional study is a critical first step in assessing differences in the drought sensitivity of food production systems and show how such an assessment enables the formulation of more targeted district and community level research that can explore the drivers of vulnerability and change on a local-scale. Finally, we propose methodological steps that can improve drought sensitivity and vulnerability assessments in dynamic dryland farming systems where there are multiple drivers of change and thresholds of risk that vary in both space and time. Results show that the vulnerability of crop production to drought in Ghana has discernible geographical and socioeconomic patterns, with the Northern, Upper West and Upper East regions being most vulnerable. Partly, this is because these regions have the lowest adaptive capacity due to low socioeconomic development and have economies based on rain-fed agriculture. Within these regions we find considerable differences between districts that can be explained only partly by socioeconomic variables with further community and household-scale research required to explain the causes of differences in vulnerability status. Our results highlight that national and regional scale multi-indicator vulnerability assessments are a vital (and often ignored) first step in assessing vulnerability across a large area. These inputs can guide both local-level research and also demonstrate the need for region-specific policies to reduce vulnerability and to enhance drought preparedness within dryland farming communities.  相似文献   

A preliminary secular variation reference curve for archaeomagnetic dating in Austria     

Elisabeth Schnepp  Philippe Lanos 《Geophysical Journal International》2006,166(1):91-96

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