Travelling and hunting in a changing Arctic: assessing Inuit vulnerability to sea ice change in Igloolik, Nunavut     

Gita J. Laidler  James D. Ford  William A. Gough  Theo Ikummaq  Alexandre S. Gagnon  Slawomir Kowal  Kevin Qrunnut  Celina Irngaut 《Climatic change》2009,94(3-4):363-397

The observations of community members and instrumental records indicate changes in sea ice around the Inuit community of Igloolik, in the Canadian territory of Nunavut. This paper characterizes local vulnerability to these changes, identifying who is vulnerable, to what stresses, and why, focusing on local and regional use of sea ice for the harvesting of renewable resources and travel. This analysis is coupled with instrumental and sea ice data to evaluate changing temperature/wind/sea ice trends over time, to complement local observations. We demonstrate the relationships between changing sea ice conditions/dynamics and harvesting activities (i.e. dangers and accessibility), with specific emphasis on ringed seal and walrus seasonal hunting, to illustrate current sea ice exposures that hunters are facing. Community members are adapting to such changes, as they have done for generations. However, current adaptive capacity is both enabled, and constrained, by social, cultural, and economic factors that manifest within the modern northern Hamlet. Enabling factors include the ability of hunters to manage or share the risks associated with sea ice travel, as well as through their flexibility in resource use, as facilitated by sophisticated local knowledge and land/navigational skills. Constraining factors include the erosion of land-based knowledge and skills, altered sharing networks, as well as financial and temporal limitations on travel/harvesting. The differential ability of community members to balance enabling and constraining factors, in relation to current exposures, comprises their level of vulnerability to sea ice change.  相似文献   

基于IBOB的射电望远镜宽带数字频谱仪系统的设计与测试     

刘东亮  John Ford  Glen Langston  南仁东 《天文研究与技术》2010,7(1)

简述了基于IBOB和Xilinx System Generator平台的射电望远镜宽带数字频谱仪系统的设计与应用;给出了双路400MHz、2048通道、16IP输出数字频谱仪系统的具体设计方案,并对该数字频谱仪器的性能指标进行了分析和测试,验证了方案的可行性;最后初步讨论了滤波器设备对后端系统的影响。  相似文献   

Mapping geochemical singularity using multifractal analysis: Application to anomaly definition on stream sediments data from Funin Sheet,Yunnan, China     

Jian Bai  Alok Porwal  Craig Hart  Arianne Ford  Le Yu 《Journal of Geochemical Exploration》2010,104(1-2):1-11

Most conventional statistical methods aiming at defining geochemical concentration thresholds for separating anomalies from background have limited effectiveness in areas with complex geological settings. This paper uses multifractal analysis to combine the characteristics of geochemical frequency distribution and spatial dispersion in order to map geochemical singularities instead of using conventional statistically derived concentration thresholds. The model, termed radius–areal Productivity (r–P) model, employs a stable measure and a scale-increasing method to estimate geochemical singularities spatially on geochemical landscape for delineating potential anomalies. The model is applied to geochemical data of regional stream sediments from the Funin Sheet, Yunnan, China.  相似文献   

High sulfate concentrations in limestone springs: An important factor in conduit initiation?     

S. R. H. Worthington  D. C. Ford 《Environmental Geology》1995,25(1):9-15

Major ion concentrations in 404 springs in carbonate strata were found to exhibit a wide range in sulfate values. Sulfate concentrations are often much larger than would be expected from the analysis of samples from surface outcrops. Springs in the Sierra Madre Oriental (Mexico), the Rocky Mountains Front Range (Canada), and the Peak District (England) show similarities in sulfate concentration and in spatial distribution. Springs with high sulfate concentrations are found close to base level and are thermal. Springs with low sulfate concentration are found at higher elevations above base level and are not thermal. There is a direct relationship between sulfate concentration and spring temperature, and an inverse relationship with discharge. The results from the three areas described support a model of local and regional flow patterns, with deep regional flow providing the warm sulfate-rich water. The initial fracture porosity development in these aquifers may owe as much to the removal of sulfur minerals as to the removal of carbonate minerals. High sulfate values are frequently found in carbonate aquifers, so this model may be of widespread applicability.  相似文献   

Regional Flow in the Baltic Shield During Holocene Coastal Regression   总被引：2，自引：0，他引：2  

Clifford I. Voss  Johan Andersson 《Ground water》1993,31(6):989-1006

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The analysis of turbulence time series: Statistical and correlation approaches using the minitab package     

N. J. Clifford 《地球表面变化过程与地形》1993,18(9):845-854

The theoretical basis and use of statistical and correlation approaches for the analysis of turbulence time series are described. In particular, the analysis of data from high frequency current meter measurements using MINITAB is presented and the data files and analytical routines are included on the software disk.  相似文献   

Geometry and pressure-temperature significance of the kyanite-sillimanite isograd in the Mica Creek area,British Columbia     

Edward D. Ghent  Philip S. Simony  Clifford C. Knitter 《Contributions to Mineralogy and Petrology》1980,74(1):67-73

Late Precambrian and Lower Paleozoic metapelitic rocks near Mica Creek, British Columbia, range in metamorphic grade from biotite zone to sillimanite zone. The kyanite-sillimanite isograd was established after phase 2 folding but was deformed by phase 3 folding. Topographic relief of about 2 km, combined with phase 3 folding, permits reasonably precise determination of the geometry of the isogradic surfaces. The effects of phase 3 folding have been accounted for and the isobaric surfaces at the time of metamorphism are inferred to have been dipping gently. Using the kyanite-sillimanite experimental phase diagram, intersection of the isobars and the isograd permits estimates of differences in temperature and pressure along a cross section. These estimates are about 400 bars and 20° C. Mineral geothermometry (garnet-biotite) and geobarometry (garnetplagioclase-Al ₂SiO₅-quartz) does not provide a fine enough resolution to detect these predicted differences.  相似文献   

The petrogenesis of peridotitic komatiites: Evidence from high-pressure melting experiments     

M.J. Bickle  C.E. Ford  E.G. Nisbet 《Earth and Planetary Science Letters》1977,37(1):97-106

The compositions of liquidus olivines and orthopyroxenes of natural specimens of spinifex- and quench-textured peridotitic komatiites from the Belingwe Greenstone Belt, Rhodesia have been determined for pressures between 10 and 40 kbars. In conjunction with the chemical variation exhibited by these peridotitic komatiites it is concluded that the more magnesian lavas cannot be derived by concentration of olivine phenocrysts, fractional crystallisation or equilibrium partial melting. The peridotitic komatiites could evolve by polybaric assimilation and complete melting of garnet lherzolite into an initial liquid containing about 24% MgO.  相似文献   

Correlation coefficient patterns and their interpretation in three basaltic suites   总被引：1，自引：0，他引：1  

K. G. Cox  P. Clifford 《Contributions to Mineralogy and Petrology》1982,79(3):268-278

Single stage magmatic fractionation processes result in igneous rock suites in which correlation coefficients between pairs of elements are generally high. The Tertiary lavas of E. Iceland are used as an illustration of this type of behaviour. When a second process such as fractionation at a different pressure, wall-rock assimilation, or mixing with a different magma, occurs, correlation coefficients are altered in a predictable way if the process and the chemical characteristics of the participating rocks, minerals and liquids are known. A computer program has been devised to simulate complete correlation coefficient matrices for any desired two- or multi-stage process e.g. fractional crystallisation coupled with contamination. Basaltic suites from Mahabaleshwar, India and the Rooi Rand, southern Africa show correlation coefficient patterns characteristic of multi-stage evolution, and these are interpreted with the aid of computer simulation. The Mahabaleshwar suite shows clear evidence of contamination by a granitic component. The Rooi Rand rocks however remain problematic.  相似文献   

Late Pleistocene sea level history of Bermuda     

Russell S. Harmon  Henry P. Schwarcz  Derek C. Ford 《Quaternary Research》1978,9(2):205-218

The timing of eustatic sea level fluctuations over the vertical range + 15 to ?11 m has been deduced from ${}^{230}\text{Th}{}^{234}\text{U}$ dating of Bermudan corals and speleothems. On this tectonically stable carbonate island, interglacial periods are characterized by platform submergence, development of patch reefs, and the deposition of littoral and eolian carbonates, whereas glacial periods are times of platform emergence, carbonate diagenesis, soil development, and the deposition of speleothems in caves extending below present sea level. Interglacial periods are observed at about 200,000, 130,000 to 90,000, and 10,000 yr BP to present. The sea level history of the last interglacial period (130,000 to 90,000 yr BP) is complex, consisting of at least two short, distinct episodes of high sea stand (at 125,000 and 97,000 yr BP) superimposed on a longer period of general platform submergence. The sea level data derived from this study are compatible with those from other stable areas such as the Bahamas, but in addition suggest that eustatic sea level changes can be rapid, on the order of 5 to 10 m/1000 yr.  相似文献