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71.
72.
Visibility Analysis with the Multiscale Implicit TIN 总被引:1,自引:0,他引:1
David B. Kidner rew J. Sparkes Mark I. Dorey J. Mark Ware & Christopher B. Jones 《Transactions in GIS》2001,5(1):19-37
Visibility analysis is now a key function of many geographical information systems. It is also one of the most contentious tools, as it is notoriously prone to error. The paper will demonstrate the versatility of the Multiscale Implicit Triangulated Irregular Network (TIN) for the application of intervisibility analysis at multiple resolutions. This approach allows for the integration of three-dimensional (3D) topographic features with the terrain surface. The multiscale TINs are derived from generalising digital contours at a variety of lateral tolerances. The models' performances are evaluated from an extensive field study undertaken in the South Wales valleys. Results suggest that the accuracy of intervisibility analysis is very dependent upon the availability of good quality 3D topographic data. In our study, such data were shown to improve visibility performance by more than 44% over its bare-earth TIN equivalent. Interestingly, generalisation of the TINs had very little effect on visibility performance. In addition, a Monte Carlo approach to sensitivity analysis was found to be detrimental to the accuracy of visibility prediction in the full terrain and topographic models. However, this probable approach can improve intervisibility performance by up to 18% on a bare-earth TIN. The range of these visibility modelling scenarios demonstrate the flexibility of the Multiscale Implicit TIN for digital surface modelling. 相似文献
73.
We implemented the windbreak model of Wang and Takle to investigate whythose authors could have obtained better agreement with the Bradley andMulhearn wind reduction measurements in the far lee of a fence, than wasobtained by Wilson using a very similar model. According to our experiencethe improvement of the Wang-Takle simulations (relative to Wilson's)largely arises from their having used a too-shallow computational domain(8H, versus Wilson's 47H; H being the windbreak height). 相似文献
74.
Jacqueline W. Curtis 《Geographical review》2016,106(3):338-359
Transcribing what is held in one's mind to a tangible map is experiencing a multidisciplinary renewal. Sketch mapping is being utilized to identify a range of community concerns, as well as for more generally revealing otherwise invisible landscapes. Whether the aim is to understand preference, perception, knowledge, or behavior, the result is some form of map. The genesis of this concept is usually attributed to seminal work in the 1960s and 1970s geography, planning, and environmental psychology. However, its resurgence in the past decade has been driven by a confluence of recent methodological and epistemological developments across numerous disciplines surrounding the role of local knowledge in ecological frameworks and how this can be mapped and analyzed with and without geospatial technologies. With growing adoption of sketch mapping well beyond its initial disciplinary niches, it is appropriate to review its evolution in order to inform ongoing and future research. 相似文献
75.
Pepin P.; Curtis K. A.; Snelgrove P. V. R.; de Young B.; Heilbig J. A. 《ICES Journal of Marine Science》2007,64(5):1075
When this article was originally published, a 相似文献
76.
Prasanna Venkatesh Sampath Hua‐Sheng Liao Zachary Kristopher Curtis Matthew E. Herbert Patrick J. Doran Christopher A. May Douglas A. Landis Shu‐Guang Li 《水文研究》2016,30(19):3390-3407
Fens, which are among the most biodiverse of wetland types in the USA, typically occur in glacial landscapes characterized by geo‐morphologic variability at multiple spatial scales. As a result, the hydrologic systems that sustain fens are complex and not well understood. Traditional approaches for characterizing such systems use simplifying assumptions that cannot adequately capture the impact of variability in geology and topography. In this study, a hierarchical, multi‐scale groundwater modelling approach coupled with a geologic model is used to understand the hydrology of a fen in Michigan. This approach uses high‐resolution data to simulate the multi‐scale topographic and hydrologic framework and lithologic data from more than 8500 boreholes in a statewide water well database to capture the complex geology. A hierarchy of dynamically linked models is developed that simulates groundwater flow at all scales of interest and to delineate the areas that contribute groundwater to the fen. The results show the fen receiving groundwater from multiple sources: an adjacent wetland, local recharge, a nearby lake and a regional groundwater mound. Water from the regional mound flows to an intermediate source before reaching the fen, forming a ‘cascading’ connection, while other sources provide water through ‘direct’ connections. The regional mound is also the source of water to other fens, streams and lakes in this area, thus creating a large, interconnected hydrologic system that sustains the entire ecosystem. In order to sustainably manage such systems, conservation efforts must include both site‐based protection and management, as well as regional protection and management of groundwater source areas. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
77.
Bohdan Kochtubajda Ronald E. Stewart Mike D. Flannigan Barrie R. Bonsal Charles Cuell Curtis J. Mooney 《大气与海洋》2019,57(1):73-90
Weather and climate are major factors influencing worldwide wildfire activity. This study assesses surface and atmospheric conditions associated with the 2014 extreme wildfires in the Northwest Territories (NWT) of Canada. Hot and dry conditions led to the NWT experiencing the most severe wildfire season in its recorded history. The season included a record number of cloud-to-ground lightning flashes and set a record for area burned. Lightning was the dominant ignition source and accounted for about 95% of the wildfires. Prolonged periods of smoke led to dramatic reductions in visibility, frequent road closures, and reduced air quality resulting in numerous health alerts. Temporal and spatial patterns of lightning characteristics in 2014, derived from Canadian Lightning Detection Network data, were different from those in other years with, for example, far more positive flashes from 0600 to 1200?utc (midnight to 6:00 am local time). The highest fraction of positive cloud-to-ground flashes (43.1%) occurred in the smoke-dominated North Slave region, which was more than in the Dehcho, South Slave, or Sahtu regions. Mid-tropospheric atmospheric circulation over a large region that included the NWT was classified into the six most common summer patterns. Results showed that ridging and ridge displacements occurred more frequently during 2014 although lightning was associated with all circulation patterns. This study has advanced the understanding of the roles of weather, lightning, and mid-tropospheric circulation patterns associated with extreme wildfires in northwestern Canada. 相似文献
78.
Y. Futaana S. Barabash M. Holmström E. Kallio H. Gunell R. Lundin M. Yamauchi J.D. Winningham J.R. Sharber A.J. Coates D.O. Kataria P. Riihelä H. Koskinen J. Luhmann D. Williams C.C. Curtis B.R. Sandel M. Carter A. Fedorov S. Orsini M. Maggi P. Bochsler N. Krupp M. Fränz C. Dierker 《Icarus》2006,182(2):424-430
The neutral particle detector (NPD) on board Mars Express has observed energetic neutral atoms (ENAs) from a broad region on the dayside of the martian upper atmosphere. We show one such example for which the observation was conducted at an altitude of 570 km, just above the induced magnetosphere boundary (IMB). The time of flight spectra of these ENAs show that they had energies of 0.2-2 keV/amu, with an average energy of ∼1.1 keV/amu. Both the spatial distribution and the energy of these ENAs are consistent with the backscattered ENAs, produced by an ENA albedo process. This is the first observation of backscattered ENAs from the martian upper atmosphere. The origin of these ENAs is considered to be the solar wind ENAs that are scattered back by collision processes in the martian upper atmosphere. The particle flux and energy flux of the backscattered ENAs are and , respectively. 相似文献
79.
Alternative Places of Detention (APODs) are a new way of detaining asylum seekers in Australia. The establishment of APODs creates a new formal structure of belonging in Australia which challenges everyday practices of belonging and senses of belonging at the local and national scale. This paper examines practices of belonging which emerged following the establishment of the Inverbrackie APOD in Woodside, South Australia. Using a critical discourse analysis approach, informed by the insights of theories of performativity, this research explores the competing stories of two broadly defined groups (opponents and supporters of Inverbrackie) engaged in a dialogue about asylum seekers, refugees, immigration detention and belonging. While opposition to the APOD was vocal and frequent in the lead-up to the establishment of the detention centre, once the Inverbrackie APOD became operational opponents’ voices began to fade. On the other hand, supporters continued to say things—and more importantly continued to do things—to nurture belonging for asylum seekers in Inverbrackie, Woodside, and Australia. 相似文献
80.