排序方式： 共有53条查询结果，搜索用时 15 毫秒
41.
Bjrn E. Berglund Svante Bjrck Geoffrey Lemdahl Helene Bergsten Kjell Nordberg Else Kolstrup 《第四纪科学杂志》1994,9(2):127-132
A synthesis is presented of the envronmental and climatic variations that are inferred to have occurred in southern Sweden (up to latitude 59°N) and Denmark during the Weichselian Late-glacial (14-9 ka BP). The chronology and characteristics of the main phases of deglaciation, sea-level change, periglacial activity, soil development, vegetation cover and climate change are summarised. A curve representing the main changes in temperature, including quantitative estimates based upon beetle data and using the ‘mutual climatic range’ method, is presented. 相似文献
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James J. Bock Andrew E. Lange T. Matsumoto Peter B. Eisenhardt Perry B. Hacking Helene R. Schember 《Experimental Astronomy》1994,3(1-4):119-120
The high sensitivity of large format InSb arrays can be used to obtain deep images of the sky at 3–5 m. In this spectral range cool or highly redshifted objects (e.g. brown dwarfs and protogalaxies) which are not visible at shorter wavelengths may be observed. Sensitivity at these wavelengths in ground-based observations is severely limited by the thermal flux from the telescope and from the earth's atmosphere. The Near Infrared Faint-Object Telescope Experiment (NIFTE), a 50 cm cooled rocket-borne telescope combined with large format, high performance InSb arrays, can reach a limiting flux < 1 Jy (1) over a large field-of-view in a single flight. In comparison, ISO will require days of observation to reach a sensitivity more than one order of magnitude worse over a similar area of the sky. The deep 3–5 m images obtained by the rocket-borne telescope will assist in determining the nature of faint red objects detected by ground-based telescopes at 2 m, and by ISO at wavelengths longer than 5 m. 相似文献
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Abu El-Enen Mahrous M. Lorenz Joachim Ali Kamal A. von Seckendorff Volker Okrusch Martin Schüssler Ulrich Brätz Helene Schmitt Ralf-Thomas 《International Journal of Earth Sciences》2018,107(7):2393-2408
International Journal of Earth Sciences - Imperial Porphyry, a famous dimension stone of spectacular purple color, was quarried in the Mons Porphyrites area north of Jabal Dokhan in the Eastern... 相似文献
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This paper aims at characterizing how different key cloud properties (cloud fraction, cloud vertical distribution, cloud reflectance, a surrogate of the cloud optical depth) vary as a function of the others over the tropical oceans. The correlations between the different cloud properties are built from 2?years of collocated A-train observations (CALIPSO-GOCCP and MODIS) at a scale close to cloud processes; it results in a characterization of the physical processes in tropical clouds, that can be used to better understand cloud behaviors, and constitute a powerful tool to develop and evaluate cloud parameterizations in climate models. First, we examine a case study of shallow cumulus cloud observed simultaneously by the two sensors (CALIPSO, MODIS), and develop a methodology that allows to build global scale statistics by keeping the separation between clear and cloudy areas at the pixel level (250, 330?m). Then we build statistical instantaneous relationships between the cloud cover, the cloud vertical distribution and the cloud reflectance. The vertical cloud distribution indicates that the optically thin clouds (optical thickness <1.5) dominate the boundary layer over the trade wind regions. Optically thick clouds (optical thickness >3.4) are composed of high and mid-level clouds associated with deep convection along the ITCZ and SPCZ and over the warm pool, and by stratocumulus low level clouds located along the East coast of tropical oceans. The cloud properties are analyzed as a function of the large scale circulation regime. Optically thick high clouds are dominant in convective regions (CF?>?80?%), while low level clouds with low optical thickness (<3.5) are present in regimes of subsidence but in convective regimes as well, associated principally to low cloud fractions (CF?<?50?%). A focus on low-level clouds allows us to quantify how the cloud optical depth increases with cloud top altitude and with cloud fraction. 相似文献
45.
Dai Panxi Gao Yongqi Counillon Fran&#;ois Wang Yiguo Kimmritz Madlen Langehaug Helene R. 《Climate Dynamics》2020,54(9):3863-3878
Climate Dynamics - The version of the Norwegian Climate Prediction Model (NorCPM) that only assimilates sea surface temperature (SST) with the Ensemble Kalman Filter has been used to investigate... 相似文献
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Hans‐Eike Gäbler Frank Melcher Torsten Graupner Andreas Bahr Maria A. Sitnikova Friedhelm Henjes‐Kunst Thomas Oberthür Helene Brätz Axel Gerdes 《Geostandards and Geoanalytical Research》2011,35(4):431-448
Coltan (the African trade name for columbite‐tantalite, a tantalum ore) is one of several raw materials that finance the civil wars in the eastern provinces of the Democratic Republic of the Congo. To improve the transparency along the tantalum trade chain, a ‘certificate of origin’ for so‐called ‘conflict minerals’ has been recommended by the United Nations. Accordingly, the German Federal Institute for Geosciences and Natural Resources (BGR) has developed an analytical fingerprint procedure for coltan. Mineral formation age, modal mineralogy and chemical composition are important fingerprint parameters. The original workflow to obtain these parameters was streamlined and is now based on mineral liberation analysis and LA‐ICP‐MS. The use of an ICP‐MS instrument with a detector system covering an extended linear dynamic range and the application of an internal standard‐independent calibration strategy allowed data for major and trace element determination and mineral formation age estimates to be obtained simultaneously. The analytical results of this new approach were compared with analytical techniques of the original workflow and showed excellent agreement in terms of mineralogical and chemical characterisation and mineral formation age of coltan samples. Within a test, samples of different origin were allocated correctly and simple, binary mixtures were also identified successfully. 相似文献
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Particulate organic and black carbon concentrations in rain were determined in various source or remote regions, in order to gain information on the incorporation of atmospheric carbonaceous particles in hydrometeors. The analyses of rainwaters indicate that all the samples contained particles derived from combustion. Data obtained on a sample basis, show an important areal and temporal variability of the composition of rain carbonaceous particles, a variability which is reported to that of the black carbon to total carbon ratio, Cb/Ct, ranging from 10 to 72%. In addition to the fluctuations of the aerosol atmospheric burden, these variations may be related to alterations of the organic fraction of the particles or their involvement in in-cloud nucleation processes during atmospheric transport. Also, a comparison of the mean relative abundance of black carbon in aerosols and in rainwaters, gives evidence of a partial disappearance of the organic particles, a phenomenon which could be due to their dissolution when incorporated in the hydrometeors. Precipitation scavenging ratio values of black carbon particles, which range from 100 to 370, are similar to those found for sulphate anthropogenic aerosols. Due to their hygroscopic properties and mean size, black carbon aerosols could possibly trace the physico-chemical processes involved in the incorporation of fine combustion particles into hydrometeors. It is also suggested that smoke particles may act as cloud condensation nuclei (CCN). Consequently, emissions of particulates derived from combustion in some tropical or industrial regions could result locally in alteration of cloud albedo and precipitation regimes. 相似文献
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Kristen Weiss Mark Hamann Michael Kinney Helene Marsh 《Global Environmental Change》2012,22(1):178-188
Few case studies have considered the impact of network structure on the resilience of complex resource management systems that operate over large spatial scales. To help fill this knowledge gap our study examined two types of relational ties—knowledge exchange and policy influence—within a marine wildlife co-management network in Northern Australia. We conducted interviews and follow-up surveys with key-informant stakeholders in dugong and marine turtle management and used these data to perform social network analysis for the dugong and turtle co-management network. The network structure of this marine governance system supports extensive cross-scale information flow, but with a disproportionate amount of top-down policy influence compared with knowledge accumulation, an arrangement that may hinder evidence-based decision making. We developed a typological ‘map’ of stakeholder roles in the network to characterize each stakeholder's contribution of knowledge and ability to influence policy, helping to identify gaps or overlaps in network linkages. Improving communication links between knowledge producers and policy makers is important for evidence based decision making throughout the management network, while addressing overlapping management roles and functions should help decrease conflict in the system. These improvements would increase social-ecological resilience in the management network by providing better protection for marine species while meeting the needs of diverse stakeholders. 相似文献