Distribution and migration of saithe (Pollachius virens) around Iceland inferred from mark-recapture studies     

Armannsson  Hlynur; Jonsson  Sigurdur Th.; Neilson  John D.; Marteinsdottir  Gudrun 《ICES Journal of Marine Science》2007,64(5):1006-1016

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The anomalous extinction law     

H. Steenman  P. S. Thé 《Astrophysics and Space Science》1991,184(1):9-30

In this paper we present further results of the calculation of anomalous extinction laws following Steenman and Thé (1989). The extinction laws in this article are calculated by enlarging the lower size cutoff of the particle size distribution, as opposed to the laws in the previous paper, which were obtained by making the upper size cutoff larger. The extinction laws we have derived have three important properties: (1) the change in the infrared is similar as in the case of changing the upper size cutoff; the difference increases as the value ofR becomes larger, (2) in the ultraviolet the 2200 Å bump disappears gradually as the lower size cutoff is made larger, (3) in the far-UV the extinction curves become more and more flat. The ultraviolet extinction laws in the direction of the stars HD 200775 and HD 259431 are lower than the Savage and Mathis (1979) galactic interstellar extinction law.  相似文献   

Observations of Ellerman bombs in H α     

Th. G. Zachariadis  C. E. Alissandrakis  G. Banos 《Solar physics》1987,108(2):227-236

A developing active region near the center of the solar disk was observed for 80 min at the center and the wings of H. Ellerman bombs lying both below an Arch Filament System and near sunspots were studied at H - 1.0 Å and H - 0.75 Å. We determined their average contrast, lifetime, size and we studied their flux as a function of time. We found evidence that the size of Ellerman bombs increases with height. The time curves of flux provide evidence for both impulsive and gradual energy release. Under the AFS the Ellerman bombs form a cellular pattern with a characteristic size of 3.1 × 10³ km. Fifty percent of the bombs appear and disappear in pairs, possibly associated with bipolar emerging magnetic flux tubes.  相似文献   

The June 2013 Alberta Catastrophic Flooding Event: Part 1—Climatological aspects and hydrometeorological features          下载免费PDF全文

A. Q. Liu  C. Mooney  K. Szeto  J. M. Thériault  B. Kochtubajda  R. E. Stewart  S. Boodoo  R. Goodson  Y. Li  J. Pomeroy 《水文研究》2016,30(26):4899-4916

In June 2013, excessive rainfall associated with an intense weather system triggered severe flooding in southern Alberta, which became the costliest natural disaster in Canadian history. This article provides an overview of the climatological aspects and large‐scale hydrometeorological features associated with the flooding event based upon information from a variety of sources, including satellite data, upper air soundings, surface observations and operational model analyses. The results show that multiple factors combined to create this unusually severe event. The event was characterized by a slow‐moving upper level low pressure system west of Alberta, blocked by an upper level ridge, while an associated well‐organized surface low pressure system kept southern Alberta, especially the eastern slopes of the Rocky Mountains, in continuous precipitation for up to two days. Results from air parcel trajectory analysis show that a significant amount of the moisture originated from the central Great Plains, transported into Alberta by a southeasterly low level jet. The event was first dominated by significant thunderstorm activity, and then evolved into continuous precipitation supported by the synoptic‐scale low pressure system. Both the thunderstorm activity and upslope winds associated with the low pressure system produced large rainfall amounts. A comparison with previous similar events occurring in the same region suggests that the synoptic‐scale features associated with the 2013 rainfall event were not particularly intense; however, its storm environment was the most convectively unstable. The system also exhibited a relatively high freezing level, which resulted in rain, rather than snow, mainly falling over the still snow‐covered mountainous areas. Melting associated with this rain‐on‐snow scenario likely contributed to downstream flooding. Furthermore, above‐normal snowfall in the preceding spring helped to maintain snow in the high‐elevation areas, which facilitated the rain‐on‐snow event. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

How to evaluate the quality of coarse‐resolution DEM‐derived drainage networks          下载免费PDF全文

Thâmara Martins Ismael Sousa  Adriano Rolim Paz 《水文研究》2017,31(19):3379-3395

The quality of digital elevation model (DEM)‐derived river drainage networks (RDNs) is influenced by DEM quality, basin physical characteristics, scale, and algorithms used; these factors should not be neglected. However, few research studies analyse the different evaluation approaches used in the literature with respect to adequacy, meaning of the results, advantages, and limitations. Focusing on coarse‐resolution networks, this paper reviews the use of these techniques and offers new insights on these issues. Additionally, we propose adaptations for selected metrics and discuss distinct interpretations for the evaluation of RDNs derived at different spatial resolutions (1, 5, 10, 20, and 30 km) considering the Uruguay River basin (206,000 km²) as a case study. The results demonstrate that lumped basin/river characteristics and basin delineation analysis should not be used as evaluation criteria for RDN quality; however, some of these metrics offer useful complementary information. Percentage of the DEM‐derived RDN within a uniform buffer placed around a river network considered as reference and mean separation distance between these two networks are more suitable metrics, but the former is insensitive to serious errors. The change in reference from a fine‐scale network to a coarse‐resolution manual tracing network significantly augments the discrepancy of these largest errors when the mean distance metric was applied, and visual comparison analysis is necessary to interpret the results for other metrics. We recommend the use of the mean distance metric in combination with a detailed visual assessment, the importance of which increases as the resolution coarsens. In both cases, the impact of network quality can be further refined by quantifying the basin shape and river length errors.  相似文献   

Vertical Patterns of Suspended Matter Characteristics Along a Coastal-basin Transect in the Western Baltic Sea     

Th. Leipe  A. Loeffler  K. -C. Emeis  S. Jaehmlich  R. Bahlo  K. Ziervogel 《Estuarine, Coastal and Shelf Science》2000,51(6):789

Suspended particulate matter samples were collected from the water column, the bottom nepheloid layer and the ‘ fluffy layer ’ from four stations along a coastal-basin transect in the Pomeranian Bight, western Baltic Sea. Sampling was performed nine times between October 1996 and December 1998 for various analyses, including electron probe x-ray micro analysis for detailed mineralogical investigations.Specific vertical patterns of clay mineral distributions were found. Suspended particulate matter (SPM) in the bottom nepheloid layer and the ‘ fluffy layer ’ overlying sediments was enriched in organic carbon and hydrated three layer clay minerals, whereas the non-aggregated SPM was dominated by quartz and biogenic opal. It appears that separation effects operate during aggregation of mineral particles and organic matter in repeated cycles of resuspension and settling. No clear seasonal variations in the composition of the SPM were found, in spite of high spatial and temporal variability of biological and physical variables. The results suggest that preferential incorporation, possibly aided by microbiological colonization, of hydrated three layer silicates into the organic flocs is a process that occurs under a wide range of conditions. Because aggregates sink faster than individual particles, aggregate formation led to a relative enrichment of illite and smectite in the near-bottom layers. Considering the affinity of organic contaminants and heavy metals to organic matter, the selective removal of aggregated organic matter and hydrated three-layer clay minerals from the water column and enhanced transport in the near-bottom fluffy layer may be a natural cleansing mechanism operating in the shallow waters of the bight.  相似文献   

Spitzer spectroscopy of carbon stars in the Small Magellanic Cloud     

Eric Lagadec  Albert A. Zijlstra  G. C. Sloan  Mikako Matsuura  Peter R. Wood  Jacco Th. van Loon  G. J. Harris  J. A. D. L. Blommaert  S. Hony  M. A. T. Groenewegen  M. W. Feast  P. A. Whitelock  J. W. Menzies  M.-R. Cioni 《Monthly notices of the Royal Astronomical Society》2007,376(3):1270-1284

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Geomorfología | Geomorfología,Mateo Gutiérrez Elorza,Pearson Educación. S.A., Prentice Hall,Madrid (2008), 920 pp. (RRP €94.99). ISBN: 978-84-8322-398-5/551.4     

Herman Th. Verstappen 《Quaternary Science Reviews》2009,28(27-28):3459-3460

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Biofuel scenarios in a water perspective: The global blue and green water footprint of road transport in 2030     

P.W. Gerbens-Leenes  A.R. van Lienden  A.Y. Hoekstra  Th.H. van der Meer 《Global Environmental Change》2012,22(3):764-775

Concerns over energy security and climate change stimulate developments towards renewable energy. Transport is expected to switch from fossil fuel use to the use of fuel mixtures with a larger fraction of biofuels, e.g. bio-ethanol and biodiesel. Growing biomass for biofuels requires water, a scarce resource. Existing scenarios on freshwater use usually consider changes in food and livestock production, and industrial and domestic activities. This research assesses global water use changes related to increasing biofuel use for road transport in 2030 and evaluates the potential contribution to water scarcity. To investigate water demand changes related to a transition to biofuels in road transport, the study combines data from water footprint (WF) analyses with information from the IEA APS energy scenario for 2030. It includes first-generation biofuels, bio-ethanol from sugar cane, sugar beet, sweet sorghum, wheat and maize, and biodiesel from soybean, rapeseed, jatropha and oil palm. Under the IEA APS scenario, the global biofuel WF will increase more than tenfold in the period 2005–2030. The USA, China and Brazil together will contribute half of the global biofuel WF. In many countries, blue biofuel WFs significantly contribute to blue water scarcity. The research provides a first exploration of the potential contribution of transport biofuel use to blue water scarcity. In 2030, the global blue biofuel WF might have grown to 5.5% of the totally available blue water for humans, causing extra pressure on fresh water resources. When biofuel use continues to expand after 2030, countries should therefore consider the water factor when investigating the extent to which biofuels can satisfy future transport energy demand.  相似文献   

Development of a methodology for assessing the environmental impact of radioactivity in Northern Marine environments     

Brown JE  Hosseini A  Børretzen P  Thørring H 《Marine pollution bulletin》2006,52(10):1127-1137

The requirement to assess the impacts of radioactivity in the environment explicitly and transparently is now generally accepted by the scientific community. A recently developed methodology for achieving this end for marine ecosystems is presented within this paper. With its clear relationship to an overarching system, the marine impact assessment is built around components of environmental transfer, ecodosimetry and radiobiological effects appraisal relying on the use of "reference organisms". Concentration factors (CFs), dynamic models and, in cases where parameters are missing, allometry have been employed in the consideration of radionuclide transfer. Dose conversion coefficients (DCCs) have been derived for selected flora and fauna using, inter alia, dose attenuation and chord distribution functions. The calculated dose-rates can be contextualised through comparison with dose-rates arising from natural background and chronic dose-rates at which biological effects have been observed in selected "umbrella" endpoints.  相似文献