Convective Redistribution of Ozone and Oxides of Nitrogen in the Troposphere over Europe in Summer and Fall     

Øystein Hov  Frode Flatøy 《Journal of Atmospheric Chemistry》1997,28(1-3):319-337

The fluxes of ozone and NO_x out of the atmospheric boundary layer (ABL) over Europe are calculated in a mesoscale chemical transport model (MCT) and compared with the net chemical production or destruction of ozone and the emissions of precursors within the ABL for two 10 days' periods which had quite different synoptic situations and levels of photochemical activity (1–10 July 1991 (JUL91) and 26 October–4 November 1994 (ON94)). Over the European continent, about 8% of the NO_x emissions were brought from the ABL to the free troposphere as NO_x, while about 15% of the NO_x emissions were brought to the free troposphere as NO_y–NO_x, i.e. as PAN or HNO₃. The convection dominates over the synoptic scale vertical advection as a transport mechanism both for NO_x and NO_y out of the boundary layer in the summertime high pressure situation (JUL91), while in the fall situation (ON94) the convective part was calculated to be the smallest. NO_x was almost completely transformed to NO_y–NO_x or removed within the ABL. Also for NO_y the major part of the atmospheric cycle is confined to the ABL both for JUL91 and ON94. The vertical transport time out of the ABL is of the order of 100h both for the total model domain and over the European continent. The net convective exchange of ozone from the ABL is not a dominant process for the amount of ozone in the ABL averaged over 10 days and the whole domain, but convection reduces the maximum ozone concentration in episodes significantly. The ozone producing efficiency of NO_x is calculated to increase with height to typically 15–20 in the upper half of the troposphere from around 5 in the ABL, but in the middle free troposphere the concentration of NO_x is often too low to cause net chemical formation of ozone there.  相似文献   

Survival of crucian carp,Carassius carassius,exposed to a high low-molecular weight inorganic aluminium challenge     

Antonio B. S. Poléo  Sigurd A. Øxnevad  Kjartan Østbye  Ronny A. Andersen  Deborah H. Oughton  Leif A. Vøllestad 《Aquatic Sciences - Research Across Boundaries》1995,57(4):350-359

Crucian carp were exposed to three combinations of pH and inorganic aluminium concentrations for 25 days. Mortality, plasma chloride and haematocrit, and gill aluminium content were investigated. No mortality was observed in any of the three exposures. Crucian carp survived acidic Al-rich water (pH 5.17) with a high concentration of low-molecular weight inorganic Al species (242 µgl^–1) for 25 days. These fish had lowered plasma chloride levels and high amounts of aluminium on their gills compared to fish exposed to acidic Al-poor water (pH 5.16 and 12 µgl^–1 Al_i) and control water (pH 6.29 and 4 µgl^–1 Al_i). Haematocrit was the same in all three exposures. Because aluminium was not acutely toxic to the anoxia tolerant crucian carp, the present results give support to the hypothesis that Al polymerization with subsequent hypoxia is of high importance for the mechanism of acute Al toxicity to fish.  相似文献   

Modelling of the long-range transport of peroxyacetylnitrate to Scandinavia     

Øystein Hov 《Journal of Atmospheric Chemistry》1984,1(2):187-202

Model calculations and field measurements have shown that when air masses accumulate emissions of hydrocarbons and nitrogen oxides from sources in continental Europe and then move towards Scandinavia without any synoptic scale break-up of the atmospheric boundary layer (e.g. frontal passages), elevated PAN concentrations in southern Norway or Sweden in the range 1–5 ppb may be caused by long-range transport. The model calculations showed that over sea, the persistence of PAN was comparable to that of ozone in an ageing air mass when the temperatures were fairly low (5–10°C). At higher temperatures the thermal decomposition of PAN made the compound less persistent than ozone. Over land, the situation may be different since the ground removal is typically three times more efficient for ozone than for PAN.According to the model, the concentration of PAN did not change very much when an ageing air mass was exposed to moderate emissions of hydrocarbons, nitrogen oxides, or both. The concentration of PAN decreased less than the concentration of ozone when an ageing air mass was exposed to high emissions of nitrogen oxides.  相似文献   

Groundwater study of a volcanic area near Bandung,Java, Indonesia     

Bogdan Pulawski  Hans Øbro 《Journal of Hydrology》1976,28(1):53-72

A hydrogeological investigation of the Bandung area, Java, Indonesia, is described. The investigation was carried out as part of a feasibility study directed towards improvement and development of the city's water supply.The area is situated in a tropic mountainous region, dominated by pyroclastic volcanic deposits and with abundant rainfall. The main activities of the investigation were compilation and evaluation of existing climatological and hydrogeological data, testing of four existing wells, a geo-electrical survey, drilling and testing of a new test well, study of water quality by analysis of samples from both springs and wells, and measurements of spring yields.The results of the investigation indicated presence of large groundwater resources within a distance of 15–20 km from the city. The feasibility study recommended that Bandung's water supply be based on these groundwater resources and this recommendation is being implemented.During the investigation some results concerning rainfall, infiltration, aquifers, geoelectrical surveying, and groundwater quality were obtained, which may be of general interest for hydrologists and geologists working in tropical volcanic and mountainous regions. These results are summarized in the conclusion of this paper.  相似文献   

Co-evolutionary dynamics and institutions: Innovation in a guild community in Norway     

Øystein Stavø Høvig 《Norsk geografisk tidsskrift. Norwegian journal of geography》2016,70(3):152-161

ABSTRACT

The video game industry is often portrayed as a ‘footloose industry’ in which electronic goods can be produced and distributed from any location without positive or negative effects from factors such as resources or proximity to market. Hence, a conventional assumption is that the role of place is greatly diminished in the case of such industries. The author tests this assumption by analysing firms’ practice in a game developer community in Bergen, Norway, and the spatiality of linkages between the community and the environment. He proposes an alternative analytical framework for understanding practice in the industry, one that recognizes that a firm's practice is either embedded within or related to networks and institutional structures. The question of how contextual conditions, embeddedness and networks are treated in the literature on innovation is discussed, and the concept of community as an analytical concept is introduced and applied. After showing how practice in the case community has evolved within the cultural, social and territorial context, the author concludes that a portrayal of the game industry as a ‘footloose industry’ disembedded from its surroundings should be avoided, and instead the dynamic relationship between actors, context and practice should be heeded.  相似文献   

Prediction of Brittle Failure for TBM Tunnels in Anisotropic Rock: A Case Study from Northern Norway     

Øyvind Dammyr 《Rock Mechanics and Rock Engineering》2016,49(6):2131-2153

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Using species distribution modelling to predict future distributions of phytoplankton: Case study using species important for the biological pump          下载免费PDF全文

Lasse Ørsted Jensen  Erik Askov Mousing  Katherine Richardson 《Marine Ecology》2017,38(3)

Some phytoplankton species have been predicted to contribute more to the biological pump than others. In this study, we examine the potential of species distribution modelling (SDM) for describing current and predicting future global distributions of two phytoplankton species: the diatom Chaetoceros diadema and the coccolithophore Emiliania huxleyi. Species distribution models (SDMs) were constructed using species data from the Ocean Biogeographic Information System and environmental layers from the Coupled Model Intercomparison Project Phase 5. The resulting distributions were evaluated by comparing predicted distributions with those found via a literature survey. The developed SDMs were then applied to predict future changes in the distributions of these species using environmental conditions based on the Intergovernmental Panel on Climate Change's Representative Concentration Pathways scenario 8.5 climate scenario, predicted for the year 2100. The model predicts that the total ocean area covered by C. diadema and E. huxleyi will decline under the examined climate scenario by 8% and 16%, respectively. Furthermore, the future ranges above depths >1,000 m are predicted to decline by 28% for C. diadema. As the biological pump is most active in deep ocean waters, this projected decrease in range in the deeper regions of the ocean may have implications for carbon sequestration, particularly for the diatom species. We conclude that SDM appears to be a robust tool for examining phytoplankton distributions. If the predicted changes in ranges of these two species under future ocean conditions are realised, this may result in a reduced contribution of these two phytoplankton species to carbon sequestration via the biological pump.  相似文献   

The 1st International Workshop on Waves,Storm Surges and Coastal Hazards incorporating the 15th International Workshop on Wave Hindcasting and Forecasting     

Swail  Val  Alves  Jose-Henrique  Breivik  Øyvind  Brown  Jennifer  Greenslade  Diana 《Ocean Dynamics》2019,69(4):513-517

Following the 1st International Workshop on Waves, Storm Surges and Coastal Hazards, which incorporated the 15th session of the long-standing the International Workshop on Wave Hindcasting and Forecasting, in September 2017 in Liverpool, United Kingdom, a topical collection has appeared in recent issues of Ocean Dynamics. Here, we give a brief overview of the 15 papers published in this topical collection as well as an overview of the widening scope of the conference in recent years. The continuing trend towards closer integration between the wave and ocean modeling communities is reflected in this workshop, culminating in the renaming of the workshop, while maintaining the connection with the three-decade long history of the wave workshop. This is also seen in this topical collection, with several papers exploring wave-generated storm surge, wave-tide contributions to coastal flooding, forcing a global ocean model with fluxes from a wave model and interaction between surface waves and sea ice.

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Sea-state contributions to sea-level variability in the European Seas     

Bonaduce  Antonio  Staneva  Joanna  Grayek  Sebastian  Bidlot  Jean-Raymond  Breivik  Øyvind 《Ocean Dynamics》2020,70(12):1547-1569

Ocean Dynamics - The contribution of sea-state-induced processes to sea-level variability is investigated through ocean-wave coupled simulations. These experiments are performed with a...  相似文献   

Multicolour photometry of EO Ceti (PB 8783)     

M. Vučković  R. H. Østensen  C. Aerts  V. S. Dhillon  T. R. Marsh 《Astrophysics and Space Science》2010,329(1-2):183-187

We present the first-look analysis of the high-speed multicolour photometry of the bright V361 Hya-type star EO?Ceti (m _V=12.3). The observations were gathered with the three-channel ULTRACAM instrument attached to the 4.2-m William Herschel Telescope. The data set has a total time span of 6.2?d and consists of 31 h simultaneous three colour photometry. The main power regions in all three colours are the same as previously reported in the white light photometric campaigns on EO?Ceti. We calculate the frequencies, amplitudes and phases of the significant modes in three colours of the SDSS system, r′, g′ and u′. The amplitudes of the detected modes are the highest in the u′ lightcurve, and the phases are the same in all three colours within the measurement accuracy. The amplitudes of the highest signal-to-noise modes show time variability in all three colours. We analyse the amplitude and phase variations of the five highest signal-to-noise modes in different colours. Even though the amplitudes show variations from night to night, the amplitude ratios are found to be constant to within 2σ level. This result is promising as it allows us to compare the observed amplitude ratios with theoretically calculated amplitude ratios. This may further constrain the mode identification of the highest amplitude modes in EO?Ceti and let us test the proposed seismic and binary evolution models.  相似文献