Results 1 - 10 of 1301
Results 1 - 10 of 1301. Search took: 0.021 seconds
|Sort by: date | relevance|
[en] The Norwegian University of Life Sciences (NMBU) started global radiation (G) measurements in 1949. PAR measurements started in 1978 as part of a Nordic project. The project terminated in 1981, but the measurements continued at NMBU. We have used the data from the Nordic project’s seven stations and the long time series from NMBU to investigate the limitations of using the relative flux density method for the estimation of PAR from G. The yearly mean value of the relative flux density PAR/G at NMBU is 0.48 with a standard deviation of 0.02. The monthly mean values of PAR/G show a seasonal variation, with its maximum (0.50) in late summer and minimum in the winter months (0.45). The seasonal variation corresponds to 15% difference in relative cloud cover. Data from the original Nordic project gave the opportunity to investigate the usability of the relative flux density method in the Nordic area. The flux ratio for July was generally larger than the ratio for September or October, even though the differences are small and not statistically significant. In trying to explain this, one obvious candidate is the cloud cover. In the lack of cloud data, time records of global radiation were used to select fair weather and overcast days. For all stations, fair days show higher flux ratios and overcast days show lower flux ratios. Neglect of cloud cover may lead to an error in the calculation of PAR from the simple formula PAR = constant G of the order of 10%.
[en] Brief history of the German quiver project and background for experiments In the German history of atoms for peace the back-end perspective changed substantially several times. Although it seemed far away when the plants started commercial operation in the seventies, a moving target on such a lang lead item can easily create problems. All German commercial plants (table 1) were equipped with an unlimited license and there was not a strict design lifetime.
[en] The personnel organization of radiation protection is one of the cornerstones for a functioning radiation protection in companies. For this reason, committee A7 of the Commission on Radiation Protection (SSK) has dealt with this topic in detail on behalf of the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety.
[de]Die personelle Organisation des Strahlenschutzes ist einer der Grundpfeiler für einen funktionierenden Strahlenschutz in den Betrieben. Aus diesem Grund hat sich der Ausschuss A7 der Strahlenschutzkommission (SSK) im Auftrag des Bundesministeriums für Umwelt, Naturschutz und nukleare Sicherheit eingehend mit diesem Thema befasst.
[en] This analysis of the frequency, intensity, and duration of thermal inversions is based on daily minimum (tn) and maximum (tx) temperatures recorded over 3 years at 16 pairs of data loggers located under forest cover in the Jura Mountains of France. Each pair consists of a logger located at the bottom of a depression and another located higher up either nearby (local site) or more than 40 km away (regional site). The daily frequency of inversions is maximum at local sites for tn (50%) and minimum for tx at regional sites (4%). The maximum intensity of the inversions reaches 15.1 °C for tn and 16.2 °C for tx. The average intensity is about 2 °C: 1.5 °C for tx at local sites and 2.4 °C at regional sites. The duration of inversions is generally short: 60% of them last less than a day. Of the inversions that last for more than 1 day, 15% exceed 3 days and the maximum duration observed is 22 days. The relationship between the diurnal amplitude of temperature and the frequency, intensity, and duration of inversions indicates that mesoscale atmospheric conditions directly influence inversions.
[en] According to its “Clean Energy for all Europeans” plan, the EU will need a significant share of its electricity mix coming from nuclear in 2050 to achieve its climate goals. Today, the French nuclear fleet represents about half of the EU capacity. As it was built very fast in the 80s, and a very large share of French reactors will reach 60 years of age between 2040 and 2050. As part of its Programmation Pluriannuelle de l’Energie (PPE)-10 year energy plan, the French government has announced in January 2019 that it lead with the industrial players by 2021 a work program to evaluate, among other things, the option of building new nuclear reactors, as part of a national industrial program. This paper features the highlights from four technical reports published by SFEN in 2018 and 2019: • The cost of new nuclear- SFEN-Mar 2018; • French nuclear in the EU energy system (PRIME simulations)- SFEN-May 2018; • Climate emergency: can we do without nuclear?- SFEN-Oct 2018; • When to decide on the renewal of the French nuclear fleet?- SFEN-Apr 2019. These reports were prepared by the Economics technical section from SFEN, as input into the national debate for the Programmation Pluri-annuelle de l’énergie (PPE) – France 10-year Energy Strategy Plan. (author)
[en] Recent and future changes in precipitation extremes over Portugal were studied. Trends in selected precipitation indices were calculated on a seasonal scale for the period of 1950–2003. Considering the same indices, this study also assessed possible changes under future climatic conditions (2046–2065). Furthermore, trends and projections for the future were evaluated using a single/unified index of extreme precipitation susceptibility (EPSI). The results revealed statistically significant drying trends in spring, mainly in northern and central Portugal, while weak wetting trends were detected in autumn. The EPSI trends also depicted a decrease of extreme precipitation in spring over central Portugal and a slight increase in autumn over northern Portugal and nearby Lisbon. On the other hand, climate change projections revealed a decrease in precipitation, mainly over northwestern Portugal, whereas the contribution of extreme precipitation to total precipitation is expected to increase, mostly in southern Portugal. The maximum number of consecutive dry days (CDD) is also projected to increase throughout Portugal. EPSI showed enhanced susceptibility for most Portuguese municipalities, which may be associated with increased vulnerability to flash floods. Climate change projections by municipality for both EPSI and CDD are an important decision support tool for civil protection and for risk management in Portugal.
[en] This study analyses spatial and temporal trends of precipitation and temperatures over Abruzzo Region (central Italy), using historical climatic data from a dense observation network. The results show a general, although not significant, negative trend in the regionally averaged annual precipitation (− 1.8% of the yearly mean rainfall per decade). This reduction is particularly evident in winter, especially at mountain stations (average − 3% change/decade). Despite this general decreasing trend, a partial rainfall recovery is observed after the 1980s. Furthermore, the majority of meteorological stations register a significant warming over the last 60 years, (mean annual temperature increase of + 0.15 °C/decade), which reflects a rise in both minimum and maximum temperatures, with the latter generally increasing at a faster rate. Spring and summer are the seasons which contribute most to the general temperature increase, in particular at high elevation sites, which exhibit a more pronounced warming (+ 0.24 °C/decade). However, this tendency has not been uniform over 1951–2012, but it has been characterised by a cooling phenomenon in the first 30 years (1951–1981), followed by an even stronger warming during the last three decades (1982–2012). Finally, correlations between the climatic variables and the dominant teleconnection patterns in the Mediterranean basin are analysed to identify the potential influence of large-scale atmospheric dynamics on observed trends in Abruzzo. The results highlight the dominant role of the East-Atlantic pattern on seasonal temperatures, while more spatially heterogeneous associations, depending on the complex topography of the region, are identified between winter precipitation and the North Atlantic Oscillation, East-Atlantic and East-Atlantic/Western Russian patterns.
[en] Determination of the site component of κ (κ0 is important in the implementation of host-to-target adjustments for estimation of seismic hazard at hard-rock sites. Its evaluation through the classical approach of Anderson and Hough (1984), κ0AS, faces specific difficulties in low-to-moderate seismicity areas because the quantity and bandwidth of the usable data are generally limited. In such a context, measurements might have higher sensitivity to site amplification, frequency-dependent attenuation, the earthquake source, and the instrumental equipment. Here, the κDS (displacement spectrum) approach of Biasi and Smith (2001) is compared with the κAS (acceleration spectrum) approach for three sites in an industrial area in Provence (south eastern France). A semiautomatic procedure is developed to measure individual values of κr that reduce interoperator variability and provide the associated uncertainty. We show that this uncertainty is mainly dependent on the bandwidth used to determine κr. A good agreement is found between κ0AS and κ0DS for the two hard-rock sites, which yield ∼30 ms. This highlights the κDS approach that is well adapted to low-magnitude events recorded at rock sites, and the use of velocimeters in low-to-moderate seismicity areas. The comparisons between these approaches are also used to infer the reliability of κ measurements by addressing their sensitivity to site amplification, frequency-dependent attenuation, and the earthquake source. First, the impact of site amplification on κ0 estimates is shown to be very important and strongly frequency-dependent for stiff-soil sites, and non-negligible for hard-rock sites. Second, frequency-dependent attenuation cannot be ruled out for κ, as indicated by comparison with the literature quality factor (Q) for the Alps. Finally, a source component for κAS is questionable from the comparison of κr AS evaluated for a cluster of events that shared the same path and site components. (authors)