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1.
Linking Inuit knowledge and meteorological station observations to understand changing wind patterns at Clyde River,Nunavut 总被引：1，自引：1，他引：0
Shari Gearheard Matthew Pocernich Ronald Stewart Joelie Sanguya Henry P. Huntington 《Climatic change》2010,100(2):267-294
Connecting indigenous and scientific observations and knowledge has received much attention in the Arctic, not least in the
area of climate change. On some levels, this connection can be established relatively easily, linking observations of similar
phenomena or of various effects stemming from the same cause. Closer examinations of specific environmental parameters, however,
can lead to far more complex and difficult attempts to make those connections. In this paper we examine observations of wind
at Clyde River, Nunavut, Canada. For Inuit, many activities are governed by environmental conditions. Wind, in particular,
is identified by Inuit as one of the most important environmental variables, playing a key role in driving sea ice, ocean,
and weather conditions that can either enable or constrain hunting, travel, or other important activities. Inuit observe wind
patterns closely, and through many means, as a result of their close connection to the land and sea. Inuit in many parts of
Nunavut are reporting changes in wind patterns in recent years. At Clyde River, a community on the eastern coast of Baffin
Island, Inuit have observed that at least three key aspects of wind have changed over the last few decades: wind variability,
wind speed, and wind direction. At the same time, wind observations are also available from an operational weather station
located at Clyde River. An analysis of this information shows little change in wind parameters since the mid-1970s. Though
the station data and Inuit observations correspond in some instances, overall, there is limited agreement. Although the differences
in the two perspectives may point to possible biases that may exist from both sources—the weather station data may not be
representative of the region, Inuit observations or explanations may be inaccurate, or the instrumental and Inuit observations
may not be of the same phenomena—they also raise interesting questions about methods for observing wind and the nature of
Arctic winds. 相似文献
2.
This paper explores the personal narratives of 12 women members of the Heiveld, a rooibos1 producer cooperative in the Northern Cape province of South Africa. It contributes to the emerging literature in geography and allied disciplines on so-called ‘alternative economies’, the aims of which often include the conceptual re-location of agency from the capitalist system to the realm of the human. This work suggests that human development – both individual and collective – is central to the success and indeed the alterity of alternative economies. The Heiveld members’ narratives support these ideas, in particular through their accounts of the importance of autonomous work and the significance of learning from and with others. We argue, however, that these narratives also foreground a theme that tends to be neglected in the alternative economies literature – that of consumption and the possession of material things. Our interviewees repeatedly emphasise buying and owning things as being among the most meaningful outcomes of alternative economic activity. They see great value both in having their own money, homes, and furnishings, and in being able to give to others. Through an analysis of the reciprocal, meaningful relationships between these women and everyday objects, we suggest that consumption is not opposed to human development but can be part of it. More attention should therefore be paid to the ways in which tangible, material things help constitute the more commonly researched, intangible benefits of alternative economic participation, such as empowerment, dignity, knowledge-sharing and care for others. 相似文献
3.
Data processing and interpretation of the nephelometer measurements made in the Venus atmosphere aboard the Venera 9, 10 and 11 landers in the sunlit hemisphere near the equator are discussed. These results were used to obtain the aerosol distribution and its microphysical properties from 62 km to the surface. The main aerosol content is found in the altitude range between 62 km (where measurements began) and 48 km, the location of the cloud region. Three prominent layers labeled as I (between 62 and 57 km), II (between 57 and 51 km) and III (between 51 and 48 km), each with different particle characteristics are discovered within the clouds. The measured light-scattering patterns can be intrepreted as having been produced by particles with effective radii from 1 to 2 μm depending on height and indices of refractivity from 1.45 in layer I to 1.42 in layer III. These values do not contradict the idea that the droplets are made of sulfuric acid. In layers II and III the particle size distribution is at least bimodal rather than uni-modal. The index of refraction is found to decrease to 1.33 in the lower part of layer II, suggesting a predominant abundance of larger particles of different chemical origin, and chlorine compounds are assumed to be relevant to this effect. In the entire heightrange of the Venera 9–11 craft descents, the clouds are rather rarefied and are characterized by a mean volume scattering coefficient σ ～ 2 × 10?5 cm?1 that corresponds to the mean meteorological range of visibility of about 2 km. The average mass content of condensate is estimated to be equal to 4 × 10?9 g/cm3, and the total optical depth of clouds to τ ～ 35. Near the bottom of layer III clouds are strongly variable. In the subcloud atmosphere a haze was observed between 48 and 32 km; that haze is mainly made of submicron particles, reff ～ 0.1μm. The atmosphere below that is totally transparent but separate (sometimes possibly disappearing) layers may be present up to a height of 8 km above the surface. A model of this region with a very low particle density (N ? 2–3 cm?3) strongly refractive large particles (reff ? 2.5 μm; 1.7 < n < 2.0) provided satisfactory agreement. The optical depth of aerosol in the atmosphere below the subcloud haze does not exceed 2.5. 相似文献
4.
The Dawson Cut Forest Bed lies in the lower part of thick, late Cenozoic loess deposits in the Fairbanks area. It is associated with several distal tephra beds that provide age control and offer the opportunity of its recognition elsewhere in central Alaska. EC tephra (named herein) occurs in the uppermost part of the Dawson Cut Forest Bed and its petrographic and chemical properties point to a co-magmatic relationship with PA tephra, which has not been found in direct association with the forest bed. Both tephra beds are pink and have unusually high Cl in their glass shards, which readily separates them from all other tephra beds in the Fairbanks area. They were produced by discrete eruptions, closely spaced in time. PA tephra has a glass-fission-track age of 2.02 ± 0.14 myr, indicating that the Dawson Cut Forest Bed must be about 2 million years old. The Palisades tephra (named herein) has very similar properties to these two tephra beds, suggesting that the buried forest bed just above it at the Palisades site on the Yukon River, about 250 km west of Fairbanks, correlates with the Dawson Cut Forest Bed. 相似文献
5.
Dawson tephra, recently recognized in the Klondike area of Yukon Territory, records one of the largest Quaternary volcanic eruptions in Beringia. Its composition is similar to that of Old Crow tephra, indicating a source in the Aleutian arc-Alaska Peninsula region of southwestern Alaska. Its primary thickness in central Yukon is nearly twice that of Old Crow tephra, which has an estimated eruption volume of >50 km3. The distribution of Dawson tephra is still poorly known, but based on its source area and occurrence in central Yukon, it should be widespread across southern Alaska, Yukon and the Gulf of Alaska. New radiocarbon ages indicate the eruption occurred at about 24,000 14C yr BP (ca 27,000 cal yr BP). The Dawson tephra is a valuable marker bed for correlating late Pleistocene records across large areas of eastern Beringia and adjacent marine records. 相似文献
6.
John A. Westgate G. William Pearce Shari J. Preece Charles E. Schweger Richard E. Morlan Nicholas J.G. Pearce T. William Perkins 《Quaternary Research》2013,79(1):75-85
Alluvial and lacustrine sediments exposed beneath late Pleistocene glaciolacustrine silt and clay at two sites along the Old Crow River, northern Yukon Territory, are rich in fossils and contain tephra beds. Surprise Creek tephra (SZt) occurs in the lower part of the alluvial sequence at CRH47 and Little Timber tephra (LTt) is present near the base of the exposure at CRH94. Surprise Creek tephra has a glass fission-track age of 0.17 ± 0.07 Ma and Little Timber tephra is 1.37 ± 0.12 Ma. All sediments at CRH47 have a normal remanent magnetic polarity and those near LTt at CRH94 have a reversed polarity — in agreement with the geomagnetic time scale. Small mammal remains from sediments near LTt support an Early Pleistocene age but the chronology is not so clear at CRH47 because of the large error associated with the SZt age determination. Tephrochronological and paleomagnetic considerations point to an MIS 7 age for the interglacial beds just below SZt at CRH47 and at Chester Bluffs in east-central Alaska, but mammalian fossils recovered from sediments close to SZt suggest a late Irvingtonian age, therefore older than MIS 7. Further studies are needed to resolve this problem. 相似文献
7.
John A. Westgate Shari J. Preece Duane G. Froese Robert C. Walter Amanjit S. Sandhu Charles E. Schweger 《Quaternary Research》2001,56(3)
The late Cenozoic deposits of central Yukon contain numerous distal tephra beds, derived from vents in the Wrangell Mountains and Aleutian arc–Alaska Peninsula region. We use a few of these tephra beds to gain a better understanding on the timing of extensive Pleistocene glaciations that affected this area. Exposures at Fort Selkirk show that the Cordilleran Ice Sheet advanced close to the outer limit of glaciation about 1.5 myr ago. At the Midnight Dome Terrace, near Dawson City, exposed outwash gravel, aeolian sand, and loess, related to valley glaciers in the adjacent Ogilvie Mountains, are of the same age. Reid glacial deposits at Ash Bend on the Stewart River are older than oxygen isotope stage (OIS) 6 and likely of OIS 8 age, that is, about 250,000 yr B.P. Supporting evidence for this chronology comes from major peaks in the rates of terrigeneous sediment input into the Gulf of Alaska at 1.5 and 0.25 myr B.P. 相似文献
8.
Shari L. Gallop Ana Vila-Concejo Thomas E. Fellowes Mitchell D. Harley Maryam Rahbani John L. Largier 《地球表面变化过程与地形》2020,45(15):3854-3868
Many estuaries contain sandy beaches that provide habitats and offer protective buffers for wetlands and infrastructure, alongside cultural and recreational resources. Research underpinning coastal management tends to focus on tide- and swell-dominated sandy beaches, but little attention is given to beaches in estuaries and bays (BEBs) that exist along a continuum of wind/swell wave, tide and riverine influence. BEBs are subject to less wave energy than open coast locations because of the generally narrow window of directions for which ocean waves can propagate through the entrance. However, when storm wave direction coincides with the orientation of the estuary or bay entrance, waves can penetrate several kilometres inside. Here we focus on eight BEBs in two major bays/estuaries in Sydney, Australia and present observations from before and after a major extratropical storm with waves from an atypical direction in June 2016. We quantify magnitudes of beach erosion and recovery rates for 3 years post-storm. We show that when high-energy storm waves penetrate bays and estuaries, BEBs can undergo up to 100% of subaerial beach erosion. Three years after the storm, only 5 of the 29 (17%) eroded subaerial beach profiles had recovered to their pre-storm volume. This is likely due to the lack of low-frequency, beach-building waves at BEBs under modal weather conditions in between storms, in contrast to open coast beaches. We also show that the recovery of BEBs may be limited by the absence of adjacent sediment reservoirs due to the dominance of tidal processes mid-channel. Our study highlights the unique behaviour of BEBs relative to beaches on the open coast, and that shifting wave direction needs to be considered in long-term beach resilience under climate change. © 2020 John Wiley & Sons, Ltd. 相似文献
9.
Interpreting data dispersion and “inverted” dates in apatite (U-Th)/He and fission-track datasets: An example from the US midcontinent 总被引：1，自引：0，他引：1
New apatite (U-Th)/He (AHe) and apatite fission-track (AFT) data were acquired for cratonic basement samples from an 80 m span of drillcore in northeastern Kansas. The short depth interval over which the samples were collected indicates that they should have undergone thermal histories that would be indistinguishable using low temperature thermochronometry techniques. Individual AHe dates from four samples range from 99 to 464 Ma. Three samples yield dates <300 Ma that display a correlation with apatite eU (9-34 ppm) and a weaker correlation with grain size. eU concentration maps of apatites from these samples reveal low to moderate zonation in eU. Results for a fourth sample are characterized by dates >300 Ma, higher eU (39-113 ppm), and substantial data dispersion uncorrelated with eU and grain size. These apatites have strong and variable eU zonation. AFT dates for five samples range from 242 to 291 Ma. The sample with the highest eU apatites and oldest AHe dates yields the youngest AFT results. These results are “inverted”, with AHe dates distinctly older than the corresponding AFT date.We explore both the causes of data dispersion and the overall compatibility of this cratonic dataset. We find that geologically reasonable thermal histories can (1) explain the distribution of the moderate eU AHe data when accounting for the influence of radiation damage, grain size, and eU zonation on apatite He diffusivity, (2) reproduce the observed dispersion in the high eU AHe data when using a viable range of eU zonation and grain size, and (3) explain the AFT data for the same samples. The AHe and AFT data are mutually consistent, and viable thermal histories successfully predict the observed pattern of older AHe than AFT dates for the high eU apatites. Together these results suggest that appropriately accounting for the known controls on apatite He diffusivity can explain the observed dispersion and “inverted” AHe and AFT results in some thermochronometry datasets. A range of AHe dates should be especially common in cratonic data, because small differences in apatite He diffusivity are amplified by the thermal histories that typify cratonic settings. We use these results to develop some guidelines for interpreting dispersed AHe datasets. First, date-eU and date-grain size correlations should be evaluated, and if these patterns occur they can be used to better resolve the thermal history. Second, for samples that yield inexplicably large dispersion of AHe dates uncorrelated with eU and crystal size, the appropriate strategy is either to reject these samples from the suite used for thermal history interpretation or to acquire additional data to help decipher the significance of the age distribution. 相似文献
10.
Modeling the effects of completion techniques and formation heterogeneity on CO2 sequestration in shallow and deep saline aquifers 总被引：1，自引：1，他引：0
This work studied the effect of completion techniques and reservoir heterogeneity on CO2 storage and injectivity in saline aquifers using a compositional reservoir simulator, CMG-GEM. Two reservoir models were
built based on the published data to represent a deep saline aquifer and a shallow aquifer. The effect of various completion
conditions on CO2 storage was then discussed, including partial perforation of the reservoir net pay (partial completion), well geometry, orientation,
location, and length. The heterogeneity effect was addressed by considering three parameters: mean permeability, the vertical
to horizontal permeability ratio, and permeability variation. Sensitivity analysis was carried out using iSIGHT software (design
of experiments) to determine the dominant factors affecting CO2 storage capacity and injectivity. Simulation results show that the most favorable option is the perforation of all layers
with horizontal wells 250–300 m long set in the upper layers. Mean permeability has the most effect on CO2 storage capacity and injectivity; k
v/k
h affects CO2 injectivity storage capacity more than permeability variation, V
k. More CO2 can be stored in the heterogeneous reservoirs with low mean permeability; however, high injectivity can be achieved in the
uniform reservoirs with high mean permeability. 相似文献