Photogrammetric Digitising Systems     

F. Urban 《The Photogrammetric Record》1981,10(58):510-510

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Erwiderung zur Diskussion Pavillon     

H. Urban 《Mineralium Deposita》1969,4(4):412-414

Ohne Zusammenfassung  相似文献   

Note on dispersion in an ocean surface Ekman layer due to variable wind forcing     

Dr. Lars Rahm  Dr. Urban Svensson 《Ocean Dynamics》1993,45(1):43-54

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Palaeogeographic significance of mid-Silurian palaeomagnetic results from southern Britain—major revision of the apparent polar wander path for eastern Avalonia     

T. H. Torsvik  A. Trench  I. Svensson  H. J. Walderhaug 《Geophysical Journal International》1993,113(3):651-668

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The sensitivity of some high-latitude boreal forests to climatic parameters   总被引：1，自引：0，他引：1  

Gordon B. Bonan  Herman H. Shugart  Dean L. Urban 《Climatic change》1990,16(1):9-29

A gap model of environmental processes and vegetation patterns in boreal forests was used to examine the sensitivity of permafrost and permafrostfree forests in interior Alaska to air temperature and precipitation changes. These analyses indicated that in the uplands of interior Alaska, the effect of climatic warming on the ecology of boreal forests may not be so much a direct response to increased air temperature as it may be a response to the increased potential evapotranspiration demands that will accompany climatic warmings. On poorlydrained north slopes with permafrost, the drier forest floor reduced the flux of heat into the soil profile. This was offset by increased fire severity, which by removing greater amounts of the forest floor increased the depth of soil thawing and converted the cold black spruce forests to warmer mixed hardwood-spruce forests. On well-drained south slopes, the increased potential water loss reduced available soil moisture, converting these mesic sites to dry aspen forests, or if too dry to steppe-like vegetation. Increases in precipitation offset the effects of increased potential evapotranspiration demands and mitigated these forest changes.  相似文献   

Ore lead isotope variations in the Proterozoic massive pyrite deposit at Näsliden,Skellefte district,Sweden     

D. Rickard  Sven-Åke Svensson 《Mineralium Deposita》1984,19(2):145-151

The ore lead isotope ratios from the Näsliden deposit are mantle-like in terms of the idealized plumbotectonics model. They suggest that the Näsliden deposit was formed in the Proterozoic equivalent of a Phanerozoic primitive island arc. The mantle-like nature of the lead and its homogeneity indicate that crustal lead does not constitute the major component of the ore lead. Crustal lead contamination is suggested to be the cause of divergences in ore lead isotopic compositions associated with later veins in the deposit.  相似文献   

Chemical and geochemical studies of Lake Biel   总被引：1，自引：0，他引：1  

Urs P. Nyffeler  Paul W. Schindler  Urban E. Wirz  Dieter M. Imboden 《Aquatic Sciences - Research Across Boundaries》1983,45(1):45-61

The mixing and transport processes in Lake Biel have been studied using the heat and excess Rn-222 as natural tracers. The mixing parameters were established in terms of coefficients of eddy diffusion in a two-dimensional box model. To account for observed transient Rn-222 distribution, transport by advection had to be included in the model calculations. Part I: Peter W. Santschi and Paul W. Schindler: A mass balance for Lake Biel and its implications for the rates of erosion of the drainage area. Schweiz. Z. Hydrol.39, 182–200 (1977).  相似文献   

广州地理信息空间基础体系建设     

杨光  方锋  王红新 《国土资源信息化》2006,(5):9-12

高质量、强现势性的城市空间数据的获取、更新和使用问题已成为当前“数字广州”建设中的瓶颈。广州地理信息空间基础体系概念的提出具有较强的前瞻性和现实意叉,其目的是在广州市建立完善的空间信息采集与应用体系,并确保信息的完整性、可靠性和现势性,从而为广州城市建设、管理等各类信息平台提供服务。本文对其中的关键技术和具体实施进行了研究。  相似文献   

The effects of extremely wet planting conditions on maize and soybean yields     

Daniel W. Urban  Michael J. Roberts  Wolfram Schlenker  David B. Lobell 《Climatic change》2015,130(2):247-260

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Reconstruction of Holocene sea-surface salinity in the Skagerrak–Kattegat: a climatic and environmental record of Scandinavia     

Hui Jiang  Svante Bjrck  Nils-Olof Svensson 《第四纪科学杂志》1998,13(2):107-114

Holocene sea-surface salinity in the Skagerrak–Kattegat is reconstructed using weighted averaging regression and calibration (WA) of diatom data from core Skagen 3. Diatom data from surface sediments together with 10-yr mean values of salinity and water temperature were used as a modern training set. Canonical correspondence analysis (CCA) was used to identify statistically significant directions of variation within the training set. The results of forward selection of the environmental variables and associated Monte Carlo permutation tests of the statistical significance of each variable, the canonical coefficients, and the intraset correlations of the environmental variables with the CCA axes suggest that summer and winter sea-surface salinities (SSS, WSS) are potentially reconstructable from fossil diatom assemblages. The changes in sea-surface salinity during the Holocene can be correlated with changes in climate of the circum-Baltic area, the current patterns of the Skagerrak–Kattegat, and the development of the Baltic Sea. Generally low SSS and large differences between WSS and SSS (ΔSw-s) during 9000–6000 yr BP might have resulted from a climate with higher precipitation than today in the circum-Baltic area and its catchment, or a climate with maximum precipitation in late spring or early summer. The mechanism behind these patterns may be the combination of the northward shift of the jet stream and a stronger surface westerly penetration into the continent caused by a reduced latitudinal insolation gradient and enhanced land–sea contrast in the early to middle Holocene. It was, however, complicated by local events such as changes in the strength of various currents in the Skagerrak–Kattegat, successions of Baltic brackish and freshwater phases, and hydrodynamic conditions in the circum-Baltic area. © 1998 John Wiley & Sons, Ltd.  相似文献