共查询到20条相似文献，搜索用时 672 毫秒
1.
3.
Trevor Fuller PhD student 《The Professional geographer》2013,65(2):272-274
A relatively simple modeling approach for estimating spatially distributed surface energy fluxes was applied to two small watersheds, one in a semi-arid climate region and one in a sub-humid region. This approach utilized a combination of ground-based meteorological data and remotely sensed data to estimate ‘instantaneous’ surface energy fluxes at the time of the satellite or aircraft overpasses. The spatial resolution in the watershed grid cells, which was on the order of 100-400 km, was selected to be compatible with ground measurements used for validation. The model estimates of surface energy fluxes compared well with ground-based measurements of surface flux (typically within approximately 40 Wm?2). The model accuracy may be slightly less for bare soil surfaces due to an overestimation of the soil heat flux. In addition to demonstrating the feasibility of computing spatially distributed values of surface energy fluxes, these maps were used to qualitatively infer the dominant factors controlling the energy fluxes for the time period shortly following precipitation events in the basins. For the semi-arid watershed, values of sensible heat flux varied considerably over the watershed and displayed a pattern very similar to that of the spatially variable cumulative precipitation for at least one to eight days prior to the image acquisition. Due to the large fraction of exposed bare soil in a semi-arid ecosystem, even very small precipitation events had a strong influence on the pattern of sensible heat fluxes observed shortly after the event (less than 24 hours). For the sub-humid watershed, the fluxes tended to be more uniform across the watershed, and were influenced by a combination of precipitation total and land cover type. 相似文献
4.
Keith Chun Leem Lee Joshua Peter Newell Jennifer Wolch Nicole Schneider Pascale Joassart-Marcelli 《社会与自然资源》2014,27(9):948-963
Despite widespread media coverage of livestock-related issues and growing scientific evidence linking meat production and climate change, systematic content analysis of this relationship in media coverage has been surprisingly minimal. In this article, we combine actor-network theory with framing theory to develop the basis for “story-networks”—networks of actants and artifacts that shape how a media report or “story” is framed. We coded livestock-related articles from a major U.S. newspaper, the Los Angeles Times, over the 1999–2010 period to understand how various actants and artifacts shaped different story-networks. Just 5% of all livestock articles addressed connections with climate change; these articles focused on technology, lifestyle, or policy. Distinctive story-networks characterized each category, framing the livestock–climate change linkage as an issue to be addressed through either technological innovation, individual lifestyle choices, or policy action. In each story-network type, varying configurations of actants and artifacts were involved, including the cattle themselves. 相似文献
5.
6.
Construction land is the leading carrier of human activities such as production and living. Evaluating the construction land suitability(CLS) on the Qinghai-Tibet Plateau(QTP) holds significant implications for harmonizing the relationship between ecological protection and human activity and promoting population and industry layout optimization. However, no relevant studies provide a complete CLS assessment of the QTP. In this study, we developed a model-based CLS evaluation framework coupling o... 相似文献
7.
Georges G. Cravins 《The Professional geographer》2013,65(1):138-141
The spatial correlation, or colocation, of two or more variables is a fundamental issue in geographical analysis but has received much less attention than the spatial correlation of values within a single variable, or autocorrelation. A recent paper by Leslie and Kronenfeld (2011) contributes to spatial correlation analysis in its development of a colocation statistic for categorical data that is interpreted in the same way as a location quotient, a frequently used measure in human geography and other branches of regional analysis. Geographically weighted colocation measures for categorical data are further developed in this article by generalizing Leslie and Kronenfeld's global measure as well as specifying a local counterpart for each global statistic using two different types of spatial filters: fixed and adaptive. These geographically weighted colocation quotients are applied to the spatial distribution of housing types to demonstrate their utility and interpretation. 相似文献
8.
9.
Crime is both a factual and perceptual component of the urban landscape, seemingly both a societal pathology and the consequence of economic disparity between social groups. Crime has a spatial structure that can be revealed by mapping. Urban crime has a spatial multiplier effect that changes the values and perceptions of how people see urban space, and which jeopardizes the quality of life of a city's inhabitants. In this research we examine the question of whether the geography of actual criminal acts is echoed by peoples' perceptions of crime, what might be termed their “spaces of fear”. We ask how the fear of crime is associated with reported urban crime. Urban crime incidents have been increasing in Viçosa, Minas Gerais, Brazil. We assembled crime information about Viçosa from two sources: first, crime as reported to the police and second, crime as perceived by city residents and measured by surveys and interviews. Reported criminal acts reveal a clustered geography, focusing particularly on the Downtown area, where there is a concentration of urban wealth and potential victims are more numerous. Offenses against property were focused on Downtown, while offenses against the person were located mostly in peripheral areas. The widespread feeling of insecurity in the city's neighborhoods, reflecting the fear of becoming a victim of violence and crime, was common throughout the city. Results confirmed the conclusion of past studies showing that the fear of violence and crime are not directly related to increasing numbers of criminal reports. Sites with higher incidence of crimes are not places with higher levels of fear. Rather than being geographically explainable “spaces of fear”, the spatial distribution of the fear of violence and crime appears to be unrelated in Viçosa, and neither is clustered or dispersed in any measurable way. 相似文献
10.
Gary Hytrek 《Urban geography》2013,34(4):496-522
Drawing on the insights of the geography, structural, and social movement literature this study analyzes the interactive effects of structure, space, place, and agency on patterns of collective action in Long Beach, California. Long Beach and Los Angeles occupy the same regional landscape with similar economies, yet the logic of collective action varies considerably. It is argued that preceding 1960, pro-business elites in Long Beach allied with their Los Angeles counterparts to spatially restrict labor organizing and foster patterns of noncontiguous interdependencies within and among labor and community groups. Through violence, cultural references, local and extralocal political policies, and regional coalition building before 1960, the Long Beach ruling elites fragmented the labor and community sector and inhibited the emergence of an organizational infrastructure necessary to foster community-based change after 1960. The legacies of this period are reflected in a fragmented labor and community sector set against a powerful ideologically driven, business-led opposition. 相似文献
11.
《Norsk geografisk tidsskrift. Norwegian journal of geography》2012,66(4):183-209
The Pikhågan caves at Svartisen, North Norway, are described and then analysed using passage morphology and scallop morphometry. The caves consist of a multilevel network of essentially horizontal phreatic tubes with a total length of 2,000 + m. Vadose elements account for only about 4% of the total passage lengths, while paragenetic roof alterations arc more common (?10%). Palcocurrcnt direction and flow rates as deduced from scallops suggest a uniform network flow southwards through the system, which also fits well with hydraulic laws for tube networks. This model requires a hydraulic conductivity between entrances formed by glacial truncation. Evidence of a subsequent sediment fill and paragenetic incision of roof half-tubes is demonstrated. These phases were followed by a lowering of the local watertable from above 610 m to about 575 m, when a phase of high discharge occurred. If this shift of watertable was caused by bedrock erosion, it probably took place more than 220 ka ago. Subsequently the watertable was lowered further to its present level (<560 m). Two alternative origins are suggested: first, a possible pre-glacial genesis of the phreatic network in a paleic valley system, second, a possible sub-glacial genesis. The paragenetic phase is regarded as the most likely to have occurred subglacially, while the coarse sediment infilling and the high discharge regime arc associated with deglaciations. The previously proposed proglacial genesis of this phreatic cave system is rejected because of the present topography and because of the slow paleocurrent regime inferred from scallop measurements. 相似文献
12.
Summary Eight variables from the 1991 Census 2% Sample of Anonymised Records are used to classify Greater London's population into ten socio-demographic groups. This provides the basis for examining differences between 'types of people' in the extent to which they changed address in the year before the Census and whether they moved into, out of or within London. 相似文献
13.
Natural Resources Research - The uniaxial compressive strength and static Young’s modulus are among the key design parameters typically used in geotechnical engineering projects. In this... 相似文献
14.
Datta K 《International journal of population geography : IJPG》1995,1(2):183-195
"The issue of return migration has been widely debated in African migration literature in view of strong rural-urban ties and urban growth based largely on in-migration. On the basis of fieldwork in Botswana, it is argued that there are important gender differences in terms of the commitment to rural and urban areas. It has been postulated in past studies that the decision to remain in towns depends in part upon urban tenure and it is argued that home owners are more likely than tenants to be permanent urban dwellers. Again, there are important gender differences and women appear to be more committed to the urban dwelling than men." 相似文献
15.
16.
Roland Pape 《Norsk geografisk tidsskrift. Norwegian journal of geography》2016,70(4):230-246
Due to increasing anthropogenic habitat alteration, fragmentation, and loss, the analysis of how, when, and why animals select particular habitats has become a central issue in ecology and biogeography. Animals adapt to spatiotemporal variability in resources either by tracking these resources or by plasticity in behavior to cover their needs, leading to three important implications: movement, temporal variation, and individual trade-offs leading to intra-species variability, all of which are directly linked to the use of space by animals. Based on GPS-tracking of domesticated reindeer in southern Norway, the authors addressed these issues by analyzing movement patterns and space use simultaneously across different temporal and organizational scales. Emerging information about the space use by reindeer was found explicitly linked to scaling relations, reflecting the matter of scale as having important functional implications rather than solely being a technical question of extent and resolution. Adding movement into the analysis of space use further advances the necessary functional perspective on space use. The authors conclude that scaling not only space but also time and the organizational level, in combination with accounting for different behavioral states, brings biogeography closer to a process-based view, rather than solely pattern-based view. 相似文献
17.
Andrew R. Goetz 《The Professional geographer》2013,65(2):298-300
This article analyzes the interrelationship among resource consumption, sociospatial justice, and what is popularly known as global warming by interrogating the ecological footprint of professional geographers, especially in terms of their conference-going involving air travel. In this spirit, the article introduces and employs the concepts of ecological privilege (as well as its inextricably related antithesis, ecological disadvantage) and dys-ecologism as a way to understand the roots and implications of professional geographers’ fossil fuel use and those of globally advantaged classes more broadly. To illustrate this, the article measures the flight-related ecological footprint of the 2011 annual meeting of the Association of American Geographers (AAG) in Seattle, Washington. In doing so, the article examines how professional geographers, in the form of the AAG, have responded to their travel-related ecological footprint. It thus highlights the importance of scrutinizing the complex and dynamic interrelationships among consumption; associated socioecological benefits and detriments and their systemic manifestations; and hierarchy-related and power-infused categories of race, class, and nation—and their spatialities. 相似文献
18.
Michael H. Finewood 《The Professional geographer》2013,65(3):468-470
California sage scrub (CSS) is a highly threatened vegetation community in coastal Southern California, 90 percent of which has been lost. Understanding CSS recovery is critical to its survival. This study compares long-term effects of grazing, cultivation, and mechanical disturbance in Southern California by tracking the extent of exotic grassland in two valleys in the Santa Monica Mountains over sixty years using aerial image analysis. Native shrubs returned to the grazed valley over one and one-half times faster than they did in the cultivated valley. Cultivation might result in a type conversion of CSS to exotic annual grassland that resembles a new steady state. 相似文献
19.
Max Lu 《The Professional geographer》2013,65(3):466-468
Landing a rescue helicopter in a wilderness environment, such as Yosemite National Park, requires suitable areas that are flat, devoid of tree canopy, and not within close proximity to other hazards. The objective of this study was to identify helicopter landing areas that are most likely to exist based on available geographic data using two GIScience methods. The first approach produced an expert model that was derived from predefined feature constraints based on existing knowledge of helicopter landing area requirements (weighted overlay algorithm). The second model is derived using a machine learning technique (maximum entropy algorithm, Maxent) that derives feature constraints from existing presence-only points; that is, geographic one-class data. Both models yielded similar output and successfully classified test coordinates, but Maxent was more efficient and required no user-defined weighting that is typically subject to human bias or disagreement. The pros and cons of each approach are discussed and the comparison reveals important considerations for a variety of future land suitability studies, including ecological niche modeling. The conclusion is that the two approaches complement each other. Overall, we produced an effective geographic information system product to support the identification of suitable landing areas in emergent rescue situations. To our knowledge, this is the first GIScience study focused on estimating the location of landing zones for a search-and-rescue application. 相似文献
20.
《地理学报(英文版)》1936,(4)
1. Gntroduction2. Trall from Nw India to Ngari Korsun3. Trail from Nepal to Tsang4. Trail from Chemonshiun (Sikkim) to Tsang andwǖ 相似文献