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Articles 241 - 270 of 384
Full-Text Articles in Geography
Spatially-Explicit Simulation Of Urban Growth Through Self-Adaptive Genetic Algorithm And Cellular Automata Modelling, Yan Liu, Yongjiu Feng, Robert Gilmore Pontius
Spatially-Explicit Simulation Of Urban Growth Through Self-Adaptive Genetic Algorithm And Cellular Automata Modelling, Yan Liu, Yongjiu Feng, Robert Gilmore Pontius
Geography
This paper presents a method to optimise the calibration of parameters and land use transition rules of a cellular automata (CA) urban growth model using a self-adaptive genetic algorithm (SAGA). Optimal calibration is achieved through an algorithm that minimises the difference between the simulated and observed urban growth. The model was applied to simulate land use change from non-urban to urban in South East Queensland's Logan City, Australia, from 1991 to 2001. The performance of the calibrated model was evaluated by comparing the empirical land use change maps from the Landsat imagery to the simulated land use change produced by …
Decolonizing Cascadia?, Wes Attewell, Dan Cohen, Juliane Collard, Rosemary Collard, Lisa Dumoulin, May Farrales, Alan Grove, Jessica Hallenbeck, Sarah Hunt, Samuel Johns, Kyle Loewen, Jonathan Luedee, Alan Mcconchie, Paige Patchin, Sage Ponder, Sarah Mathisen Przedpelska, Carolyn Prouse, Duncan Ranslem, Max Ritts, Emily Rosenman, Sam Walker, Sophie Webber
Decolonizing Cascadia?, Wes Attewell, Dan Cohen, Juliane Collard, Rosemary Collard, Lisa Dumoulin, May Farrales, Alan Grove, Jessica Hallenbeck, Sarah Hunt, Samuel Johns, Kyle Loewen, Jonathan Luedee, Alan Mcconchie, Paige Patchin, Sage Ponder, Sarah Mathisen Przedpelska, Carolyn Prouse, Duncan Ranslem, Max Ritts, Emily Rosenman, Sam Walker, Sophie Webber
Geography
This essay reflects on attempts to organize a conference that sought to trouble the colonial nature of conference structures, academic knowledges and hierarchies, and the ‘Cascadia’ bioregion of Northwestern North America.
Convergent Surface Water Distributions In U.S. Cities, M. K. Steele, J. B. Heffernan, N. Bettez, J. Cavender-Bares, P. M. Groffman, J. M. Grove, S. Hall, S. E. Hobbie, K. Larson, J. L. Morse, C. Neill, K. C. Nelson, J. O'Neil-Dunne, L. Ogden, D. E. Pataki, C. Polsky, Rinku Roy Chowdhury
Convergent Surface Water Distributions In U.S. Cities, M. K. Steele, J. B. Heffernan, N. Bettez, J. Cavender-Bares, P. M. Groffman, J. M. Grove, S. Hall, S. E. Hobbie, K. Larson, J. L. Morse, C. Neill, K. C. Nelson, J. O'Neil-Dunne, L. Ogden, D. E. Pataki, C. Polsky, Rinku Roy Chowdhury
Geography
Earth's surface is rapidly urbanizing, resulting in dramatic changes in the abundance, distribution and character of surface water features in urban landscapes. However, the scope and consequences of surface water redistribution at broad spatial scales are not well understood. We hypothesized that urbanization would lead to convergent surface water abundance and distribution: in other words, cities will gain or lose water such that they become more similar to each other than are their surrounding natural landscapes. Using a database of more than 1 million water bodies and 1 million km of streams, we compared the surface water of 100 US …
Extractive Industries, Livelihoods And Natural Resource Competition: Mapping Overlapping Claims In Peru And Ghana, Nicholas Cuba, Anthony J. Bebbington, John Rogan, Marco Millones
Extractive Industries, Livelihoods And Natural Resource Competition: Mapping Overlapping Claims In Peru And Ghana, Nicholas Cuba, Anthony J. Bebbington, John Rogan, Marco Millones
Geography
Taking the cases of Perú and Ghana, this paper examines overlaps between the extraction of minerals, oil and gas on the one hand, and river basins, agricultural land use, and protected areas on the other hand. In particular the paper considers how far such overlaps can be revealed and analyzed on the basis of (relatively) accessible and affordable data, without having to use more expensive data generated by remote sensing or fieldwork. We use concessions as our indicator of the presence of extractive industry activity, focusing on both mineral and hydrocarbon concessions, and areas of exploration and of active resource …
Heat And Drought Extremes Likely To Stress Ecosystem Productivity Equally Or More In A Warmer, Co2rich Future, Christopher A. Williams
Heat And Drought Extremes Likely To Stress Ecosystem Productivity Equally Or More In A Warmer, Co2rich Future, Christopher A. Williams
Geography
Reduced carbon uptake caused by recent heat and drought extremes raises concerns about biospheric feedbacks that amplify global warming. However, elevated carbon dioxide is expected to boost terrestrial ecosystem productivity over the 21st century, potentially alleviating some of the adverse carbon impacts of climate extremes. Using CMIP5 earth system model (ESM) results, Ian Williams and colleagues (2014 Environ. Res. Lett. 9 094011) find that the carbon impacts of heat and drought extremes in the future are likely to be similar to those seen in today's climate only shifted toward fluctuations around a higher average temperature. However, they also find that …
A Full Greenhouse Gases Budget Of Africa: Synthesis, Uncertainties, And Vulnerabilities, R. Valentini, A. Arneth, A. Bombelli, S. Castaldi, R. Cazzolla Gatti, F. Chevallier, P. Ciais, E. Grieco, J. Hartmann, M. Henry, R. A. Houghton, M. Jung, W. L. Kutsch, Y. Malhi, E. Mayorga, L. Merbold, G. Murray-Tortarolo, D. Papale, P. Peylin, B. Poulter, P. A. Raymond, M. Santini, S. Sitch, G. Vaglio Laurin, G. R. Van Der Werf, Christopher A. Williams, R. J. Scholes
A Full Greenhouse Gases Budget Of Africa: Synthesis, Uncertainties, And Vulnerabilities, R. Valentini, A. Arneth, A. Bombelli, S. Castaldi, R. Cazzolla Gatti, F. Chevallier, P. Ciais, E. Grieco, J. Hartmann, M. Henry, R. A. Houghton, M. Jung, W. L. Kutsch, Y. Malhi, E. Mayorga, L. Merbold, G. Murray-Tortarolo, D. Papale, P. Peylin, B. Poulter, P. A. Raymond, M. Santini, S. Sitch, G. Vaglio Laurin, G. R. Van Der Werf, Christopher A. Williams, R. J. Scholes
Geography
This paper, developed under the framework of the RECCAP initiative, aims at providing improved estimates of the carbon and GHG (CO2, CH4 and N2O) balance of continental Africa. The various components and processes of the African carbon and GHG budget are considered, existing data reviewed, and new data from different methodologies (inventories, ecosystem flux measurements, models, and atmospheric inversions) presented. Uncertainties are quantified and current gaps and weaknesses in knowledge and monitoring systems described in order to guide future requirements. The majority of results agree that Africa is a small sink of carbon on an annual scale, with an average …
Impacts Of Disturbance History On Forest Carbon Stocks And Fluxes: Merging Satellite Disturbance Mapping With Forest Inventory Data In A Carbon Cycle Model Framework, Christopher A. Williams, G. James Collatz, Jeffrey Masek, Chengquan Huang, Samuel N. Goward
Impacts Of Disturbance History On Forest Carbon Stocks And Fluxes: Merging Satellite Disturbance Mapping With Forest Inventory Data In A Carbon Cycle Model Framework, Christopher A. Williams, G. James Collatz, Jeffrey Masek, Chengquan Huang, Samuel N. Goward
Geography
Forest carbon stocks and fluxes are highly dynamic following stand-clearing disturbances from severe fire and harvest and this presents a significant challenge for continental carbon budget assessments. In this work we use forest inventory data to parameterize a carbon cycle model to represent post-disturbance carbon trajectories of carbon pools and fluxes for specific forest types growing in high and low site productivity class settings. We then apply these trajectories to landscapes and regions based on forest age distributions derived from either the FIA data or from Landsat time series stacks (1985-2006) for 54 representative scenes throughout most of the conterminous …
The Research Journey: Travels Across The Idiomatic And Axiomatic Toward A Better Understanding Of Complexity, Katharine A. Mcgowan, Frances Westley, Evan D.G. Fraser, Philip A. Loring, Kathleen C. Weathers, Flor Avelino, Jan Sendzimir, Rinku Roy Chowdhury, Michele Lee Moore
The Research Journey: Travels Across The Idiomatic And Axiomatic Toward A Better Understanding Of Complexity, Katharine A. Mcgowan, Frances Westley, Evan D.G. Fraser, Philip A. Loring, Kathleen C. Weathers, Flor Avelino, Jan Sendzimir, Rinku Roy Chowdhury, Michele Lee Moore
Geography
In this paper, seven researchers reflect on the journeys their research projects have taken when they engage with and synthesize complex problems. These journeys embody an adaptive approach to tackling problems characterized by their interconnectedness and emergence, and that transcend traditional units of analysis such as ecosystems. In this paper we argue that making such a process deliberate and explicit will help researchers better combine different research paradigms such as expert-driven and participant-directed work, thus resulting in both broad explanations and specific phenomenon; research tensions traditionally defined as oppositional must be approached as complimentary. This paper includes researchers’ personal journeys …
Spatiotemporal Patterns And Socioeconomic Contexts Of Vegetative Cover In Altamira City, Brazil, Scott Hetrick, Rinku Roy Chowdhury, Eduardo Brondizio, Emilio Moran
Spatiotemporal Patterns And Socioeconomic Contexts Of Vegetative Cover In Altamira City, Brazil, Scott Hetrick, Rinku Roy Chowdhury, Eduardo Brondizio, Emilio Moran
Geography
Ecosystem services provided by urban vegetation can ameliorate problems common to urban environments while improving the quality of life of urban residents. Much research in urban ecology has analyzed urban environmental dynamics in the global north; rapidly urbanizing areas in the global south have not received commensurate attention. The land cover dynamics of mid-sized cities in the global south remain under-explored in particular. In this article, we investigate the spatial patterns and socioeconomic contexts of urban vegetation in Altamira, Brazil, a mid-sized but rapidly expanding city in the Amazon. Using time series remotely sensed imagery, we profile changes in urban …
Design And Interpretation Of Intensity Analysis Illustrated By Land Change In Central Kalimantan, Indonesia, Robert Gilmore Pontius, Yan Gao, Nicholas M. Giner, Takashi Kohyama, Mitsuru Osaki, Kazuyo Hirose
Design And Interpretation Of Intensity Analysis Illustrated By Land Change In Central Kalimantan, Indonesia, Robert Gilmore Pontius, Yan Gao, Nicholas M. Giner, Takashi Kohyama, Mitsuru Osaki, Kazuyo Hirose
Geography
Intensity Analysis has become popular as a top-down hierarchical accounting framework to analyze differences among categories, such as changes in land categories over time. Some aspects of interpretation are straightforward, while other aspects require deeper thought. This article explains how to interpret Intensity Analysis with respect to four concepts. First, we illustrate how to analyze whether error could account for non-uniform changes. Second, we explore two types of the large dormant category phenomenon. Third, we show how results can be sensitive to the selection of the domain. Fourth, we explain how Intensity Analysis' symmetric top-down hierarchy influences interpretation with respect …
A Suite Of Tools For Roc Analysis Of Spatial Models, Jean François Mas, Britaldo Soares Filho, Robert Gilmore Pontius, Michelle Farfán Gutiérrez, Hermann Rodrigues
A Suite Of Tools For Roc Analysis Of Spatial Models, Jean François Mas, Britaldo Soares Filho, Robert Gilmore Pontius, Michelle Farfán Gutiérrez, Hermann Rodrigues
Geography
The Receiver Operating Characteristic (ROC) is widely used for assessing the performance of classification algorithms. In GIScience, ROC has been applied to assess models aimed at predicting events, such as land use/cover change (LUCC), species distribution and disease risk. However, GIS software packages offer few statistical tests and guidance tools for ROC analysis and interpretation. This paper presents a suite of GIS tools designed to facilitate ROC curve analysis for GIS users by applying proper statistical tests and analysis procedures. The tools are freely available as models and submodels of Dinamica EGO freeware. The tools give the ROC curve, the …
Measuring The Temporal Instability Of Land Change Using The Flow Matrix, D. S.M. Runfola, Robert Gilmore Pontius
Measuring The Temporal Instability Of Land Change Using The Flow Matrix, D. S.M. Runfola, Robert Gilmore Pontius
Geography
This article introduces the Flow matrix, which expresses the sizes of transitions among categories between two time points. We use the Flow matrix to create a metric R that measures the instability of annual change among time intervals that partition the time extent. Specifically, R is the proportion of change that would need to be reallocated to different time interval(s) to achieve uniform change during the time extent. This article computes R for 10 Long Term Ecological Research (LTER) sites and for seven case studies from published land change data. Of the 10 LTER sites analyzed, the Andrews site in …
Global Trends In Seasonality Of Normalized Difference Vegetation Index (Ndvi), 1982-2011, J. Ronald Eastman, Florencia Sangermano, Elia A. Machado, John Rogan, Assaf Anyamba
Global Trends In Seasonality Of Normalized Difference Vegetation Index (Ndvi), 1982-2011, J. Ronald Eastman, Florencia Sangermano, Elia A. Machado, John Rogan, Assaf Anyamba
Geography
A 30-year series of global monthly Normalized Difference Vegetation Index (NDVI) imagery derived from the Global Inventory Modeling and Mapping Studies (GIMMS) NDVI3g archive was analyzed for the presence of trends in changing seasonality. Using the Seasonal Trend Analysis (STA) procedure, over half (56.30%) of land surfaces were found to exhibit significant trends. Almost half (46.10%) of the significant trends belonged to three classes of seasonal trends (or changes). Class 1 consisted of areas that experienced a uniform increase in NDVI throughout the year, and was primarily associated with forested areas, particularly broadleaf forests. Class 2 consisted of areas experiencing …
Do Bark Beetle Outbreaks Increase Wildfire Risks In The Central U.S. Rocky Mountains? Implications From Recent Research, Scott H. Black, Dominik Kulakowski, Barry R. Noon, Dominick A. Dellasala
Do Bark Beetle Outbreaks Increase Wildfire Risks In The Central U.S. Rocky Mountains? Implications From Recent Research, Scott H. Black, Dominik Kulakowski, Barry R. Noon, Dominick A. Dellasala
Geography
Appropriate response to recent, widespread bark beetle (Dendroctonus spp.) outbreaks in the western United States has been the subject of much debate in scientific and policy circles. Among the proposed responses have been landscape-level mechanical treatments to prevent the further spread of outbreaks and to reduce the fire risk that is believed to be associated with insect-killed trees. We review the literature on the efficacy of silvicutural practices to control outbreaks and on fire risk following bark beetle outbreaks in several forest types. While research is ongoing and important questions remain unresolved, to date most available evidence indicates that bark …
We Have Never Been "Post-Political", James Mccarthy
We Have Never Been "Post-Political", James Mccarthy
Geography
The Progressive Era attempt to 'depoliticize' environmental governance was of course an utter failure for a host of reasons: powerful economic and political interests found or made entry points into supposedly sealed-off arenas, eventually culminating in the phenomenon of agency capture. Scientists and technocrats carried their own politics into their work, consciously or unconsciously; the people affected by new property relations and management regimes resisted and reconfigured the newly emergent socionatures in their areas in a variety of ways, producing a reality more complicated than, and often at odds with, the superficially clear official policy; and so on. It is …
Global Land Governance: From Territory To Flow?, Thomas Sikor, Graeme Auld, Anthony J. Bebbington, Tor A. Benjaminsen, Bradford S. Gentry, Carol Hunsberger, Anne Marie Izac, Matias E. Margulis, Tobias Plieninger, Heike Schroeder, Caroline Upton
Global Land Governance: From Territory To Flow?, Thomas Sikor, Graeme Auld, Anthony J. Bebbington, Tor A. Benjaminsen, Bradford S. Gentry, Carol Hunsberger, Anne Marie Izac, Matias E. Margulis, Tobias Plieninger, Heike Schroeder, Caroline Upton
Geography
This article reviews recent research on contemporary transformations of global land governance. It shows how changes in global governance have facilitated and responded to radical revalorizations of land, together driving the intensified competition and struggles over land observed in many other contributions to this special issue. The rules in place to govern land use are shifting from 'territorial' toward 'flow-centered' arrangements, the latter referring to governance that targets particular flows of resources or goods, such as certification of agricultural or wood products. The intensifying competition over land coupled with shifts toward flow-centered governance has generated land uses involving new forms …
Improving Operational Land Surface Model Canopy Evapotranspiration In Africa Using A Direct Remote Sensing Approach, M. Marshall, K. Tu, C. Funk, J. Michaelsen, P. Williams, Christopher A. Williams, J. Ardö, M. Boucher, B. Cappelaere, A. De Grandcourt, A. Nickless, Y. Nouvellon, R. Scholes, W. Kutsch
Improving Operational Land Surface Model Canopy Evapotranspiration In Africa Using A Direct Remote Sensing Approach, M. Marshall, K. Tu, C. Funk, J. Michaelsen, P. Williams, Christopher A. Williams, J. Ardö, M. Boucher, B. Cappelaere, A. De Grandcourt, A. Nickless, Y. Nouvellon, R. Scholes, W. Kutsch
Geography
Climate change is expected to have the greatest impact on the world's economically poor. In the Sahel, a climatically sensitive region where rain-fed agriculture is the primary livelihood, expected decreases in water supply will increase food insecurity. Studies on climate change and the intensification of the water cycle in sub-Saharan Africa are few. This is due in part to poor calibration of modeled evapotranspiration (ET), a key input in continental-scale hydrologic models. In this study, a remote sensing model of transpiration (the primary component of ET), driven by a time series of vegetation indices, was used to substitute transpiration from …
Satellite-Based Estimates Of Antarctic Surface Meltwater Fluxes, Luke D. Trusel, Karen E. Frey, Sarah B. Das, Peter Kuipers Munneke, Michiel R. Van Den Broeke
Satellite-Based Estimates Of Antarctic Surface Meltwater Fluxes, Luke D. Trusel, Karen E. Frey, Sarah B. Das, Peter Kuipers Munneke, Michiel R. Van Den Broeke
Geography
This study generates novel satellite-derived estimates of Antarctic-wide annual (1999-2009) surface meltwater production using an empirical relationship between radar backscatter from the QuikSCAT (QSCAT) satellite and melt calculated from in situ energy balance observations. The resulting QSCAT-derived melt fluxes significantly agree with output from the regional climate model RACMO2.1 and with independent ground-based observations. The high-resolution (4.45 km) QSCAT-based melt fluxes uniquely detect interannually persistent and intense melt (>400 mm water equivalent (w.e.) year-1) on interior Larsen C Ice Shelf that is not simulated by RACMO2.1. This supports a growing understanding of the importance of a föhn effect in …
Ice Sheet Record Of Recent Sea-Ice Behavior And Polynya Variability In The Amundsen Sea, West Antarctica, Alison S. Criscitiello, Sarah B. Das, Matthew J. Evans, Karen E. Frey, Howard Conway, Ian Joughin, Brooke Medley, Eric J. Steig
Ice Sheet Record Of Recent Sea-Ice Behavior And Polynya Variability In The Amundsen Sea, West Antarctica, Alison S. Criscitiello, Sarah B. Das, Matthew J. Evans, Karen E. Frey, Howard Conway, Ian Joughin, Brooke Medley, Eric J. Steig
Geography
[1] Our understanding of past sea-ice variability is limited by the short length of satellite and instrumental records. Proxy records can extend these observations but require further development and validation. We compare methanesulfonic acid (MSA) and chloride (Cl-) concentrations from a new firn core from coastal West Antarctica with satellite-derived observations of regional sea-ice concentration (SIC) in the Amundsen Sea (AS) to evaluate spatial and temporal correlations from 2002-2010. The high accumulation rate (∼39 g·cm-2·yr-1) provides monthly resolved records of MSA and Cl-, allowing detailed investigation of how regional SIC is recorded in the ice-sheet stratigraphy. Over the period 2002-2010 …
Predicting How Adaptation To Climate Change Could Affect Ecological Conservation: Secondary Impacts Of Shifting Agricultural Suitability, Bethany A. Bradley, Lyndon D. Estes, David G. Hole, Stephen Holness, Michael Oppenheimer, Will R. Turner, Hein Beukes, Roland E. Schulze, Mark A. Tadross, David S. Wilcove
Predicting How Adaptation To Climate Change Could Affect Ecological Conservation: Secondary Impacts Of Shifting Agricultural Suitability, Bethany A. Bradley, Lyndon D. Estes, David G. Hole, Stephen Holness, Michael Oppenheimer, Will R. Turner, Hein Beukes, Roland E. Schulze, Mark A. Tadross, David S. Wilcove
Geography
Aim: Ecosystems face numerous well-documented threats from climate change. The well-being of people also is threatened by climate change, most prominently by reduced food security. Human adaptation to food scarcity, including shifting agricultural zones, will create new threats for natural ecosystems. We investigated how shifts in crop suitability because of climate change may overlap currently protected areas (PAs) and priority sites for PA expansion in South Africa. Predicting the locations of suitable climate conditions for crop growth will assist conservationists and decision-makers in planning for climate change. Location: South Africa. Methods: We modelled climatic suitability in 2055 for maize and …
Heterogeneity In Residential Yard Care: Evidence From Boston, Miami, And Phoenix, Edmund M. Harris, Colin Polsky, Kelli L. Larson, Rebecca Garvoille, Deborah Martin, Jaleila Brumand, Laura Ogden
Heterogeneity In Residential Yard Care: Evidence From Boston, Miami, And Phoenix, Edmund M. Harris, Colin Polsky, Kelli L. Larson, Rebecca Garvoille, Deborah Martin, Jaleila Brumand, Laura Ogden
Geography
The management of residential landscapes occurs within a complex socio-ecological system linking household decision-making with ecological properties, multi-scalar human drivers, and the legacy effects of past management. Conventional wisdom suggests that resource-intensive turf grass yards are the most common landscaping outcome, resulting in a presumed homogeneous set of residential landscaping practices throughout North America. We examine this homogenization thesis through an interview-based, cross-site study of residential landscape management in Boston, Phoenix, and Miami. Counter to the homogeneity thesis, we find that yard management practices often exhibit heterogeneity, for example, in groundcover choice or use of chemical inputs. The degree of …
Global Production Networks, Relational Proximity, And The Sociospatial Dynamics Of Market Internationalization In Bolivia's Wood Products Sector, James T. Murphy
Global Production Networks, Relational Proximity, And The Sociospatial Dynamics Of Market Internationalization In Bolivia's Wood Products Sector, James T. Murphy
Geography
This article advances conceptualizations of global production networks (GPNs) through an analysis of the relational processes that firms in Bolivia's growing wood products industry use to build ties to international markets. Both large- and small-scale manufacturers are increasingly internationalizing their operations in response to the global demand for tropical hardwoods and decentralization of control over the country's forest resources. These firms use four different types of production networks and networking practices to develop international market ties. Each of these networks is distinguishable by its entry barriers, value-creation possibilities, upgrading strategies, and the cognitive, social, and cultural factors that influence who …
Accelerating Anthropogenic Land Surface Change And The Status Of Pleistocene Drumlins In New England, Deborah W. Woodcock, John S. Rogan, Samuel D. Blanchard
Accelerating Anthropogenic Land Surface Change And The Status Of Pleistocene Drumlins In New England, Deborah W. Woodcock, John S. Rogan, Samuel D. Blanchard
Geography
Drumlins are glacially derived landforms that are prominent in the landscape over much of southern New England. We carried out a comprehensive ground-based survey in a three-town study area in eastern Massachusetts with the goals of establishing the extent to drumlins have been altered and assessing the associated environmental consequences and probable driving factors. Results show that many drumlins have been significantly altered through levelling and truncation (creation of steep cut and fill slopes), with projects involving movement of 1-1.5×106 m3 of earth materials not now uncommon. Stormwater and wetlands infractions were documented at all the larger excavation sites and …
Error Propagation In Raster Data Integration: Impacts On Landscape Composition And Configuration, Zachary J. Christman, John Rogan
Error Propagation In Raster Data Integration: Impacts On Landscape Composition And Configuration, Zachary J. Christman, John Rogan
Geography
Integrating raster-based categorical maps from multiple sources necessitates the transformation of geometric characteristics to compare maps, as in land change analyses. By projecting maps to a new geographic reference framework and scaling pixel values to a new size, distortions of map information are introduced that can affect the proportion and arrangement of thematic classes across the landscape. Using a sample land cover dataset depicting a heterogeneous landscape, this paper examines these impacts using three common raster-based transformation methods and introduces a new vector-based method that minimizes error propagation. While relative class area was best preserved by a nearest-neighbor resampling method, …
Antarctic Surface Melting Dynamics: Enhanced Perspectives From Radar Scatterometer Data, L. D. Trusel, K. E. Frey, S. B. Das
Antarctic Surface Melting Dynamics: Enhanced Perspectives From Radar Scatterometer Data, L. D. Trusel, K. E. Frey, S. B. Das
Geography
Antarctic ice sheet surface melting can regionally influence ice shelf stability, mass balance, and glacier dynamics, in addition to modulating near-surface physical and chemical properties over wide areas. Here, we investigate variability in surface melting from 1999 to 2009 using radar backscatter time series from the SeaWinds scatterometer aboard the QuikSCAT satellite. These daily, continent-wide observations are explored in concert with in situ meteorological records to validate a threshold-based melt detection method. Radar backscatter decreases during melting are significantly correlated with in situ positive degree-days as well as meltwater production determined from energy balance modeling at Neumayer Station, East Antarctica. …
Enso And Iod Teleconnections For African Ecosystems: Evidence Of Destructive Interference Between Climate Oscillations, Christopher A. Williams, N. P. Hanan
Enso And Iod Teleconnections For African Ecosystems: Evidence Of Destructive Interference Between Climate Oscillations, Christopher A. Williams, N. P. Hanan
Geography
Rainfall and vegetation across Africa are known to resonate with the coupled ocean-atmosphere phenomena of El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD). However, the regional-scale implications of sea surface temperature variability for Africa's photosyntheis have received little focused attention, particularly in the case of IOD. Furthermore, studies exploring the interactive effects of ENSO and IOD when coincident are lacking. This analysis uses remotely sensed vegetation change plus a land surface model driven with observed meteorology to investigate how rainfall, vegetation, and photosynthesis across Africa respond to these climate oscillations. In addition to the relatively well-known ENSO …
Theorizing Practice In Economic Geography: Foundations, Challenges, And Possibilities, Andrew Jones, James T. Murphy
Theorizing Practice In Economic Geography: Foundations, Challenges, And Possibilities, Andrew Jones, James T. Murphy
Geography
Over the last decade or so there has been an identifiable shift in the interests of many economic geographers towards a concern with practices: stabilized, routinized, or improvised social actions that constitute and reproduce economic space, and through and within which socioeconomic actors and communities embed knowledge, organize production activities, and interpret and derive meaning from the world. Although this shift has gained significant momentum its general theoretical significance remains somewhat unclear and the concept is vulnerable to criticisms that it is incoherent, too 'micro-scale' in emphasis, unable to provide valid links between everyday practices and higher-order phenomena (eg, institutions, …
Detection Of The Timing And Duration Of Snowmelt In The Hindu Kush-Himalaya Using Quikscat, 2000-2008, Prajjwal K. Panday, Karen E. Frey, Bardan Ghimire
Detection Of The Timing And Duration Of Snowmelt In The Hindu Kush-Himalaya Using Quikscat, 2000-2008, Prajjwal K. Panday, Karen E. Frey, Bardan Ghimire
Geography
The Hindu Kush-Himalayan (HKH) region holds the largest mass of ice in Central Asia and is highly vulnerable to global climate change, experiencing significant warming (0.21 ± 0.08 °C/decade) over the past few decades. Accurate monitoring of the timing and duration of snowmelt across the HKH region is important, as this region is expected to experience further warming in response to increased greenhouse gas forcing. Despite the many advantages and applications of satellite-derived radar scatterometer data shown for capturing ice and snow melt dynamics at high latitudes, similar comprehensive freeze/thaw detection studies at lower latitudes (including the HKH region) are …
Evaluation Of Species Distribution Model Algorithms For Fine-Scale Container-Breeding Mosquito Risk Prediction, C. Khatchikian, Florencia Sangermano, D. Kendell, T. Livdahl
Evaluation Of Species Distribution Model Algorithms For Fine-Scale Container-Breeding Mosquito Risk Prediction, C. Khatchikian, Florencia Sangermano, D. Kendell, T. Livdahl
Geography
The present work evaluates the use of species distribution model (SDM) algorithms to classify high densities of small container-breeding Aedes mosquitoes (Diptera: Culicidae) on a fine scale in the Bermuda Islands. Weekly ovitrap data collected by the Department of Health, Bermuda for the years 2006 and 2007 were used for the models. The models evaluated included the algorithms Bioclim, Domain, GARP (genetic algorithm for rule-set prediction), logistic regression and MaxEnt (maximum entropy). Models were evaluated according to performance and robustness. The area under the receiver operating characteristic curve was used to evaluate each model's performance, and robustness was assessed according …
Utilizing Temporally Invariant Calibration Sites To Classify Multiple Dates And Types Of Satellite Imagery, Joe Fortier, John Rogan, Curtis E. Woodcock, Daniel Miller Runfola
Utilizing Temporally Invariant Calibration Sites To Classify Multiple Dates And Types Of Satellite Imagery, Joe Fortier, John Rogan, Curtis E. Woodcock, Daniel Miller Runfola
Geography
Mapping past time periods (retrospective mapping) using remotely sensed data is hindered by a lack of coincident calibration and validation information. The identification of features of same ground cover invariant across time and their use as calibration and validation data addresses this challenge by: (a) streamlining the process of image calibration for multiple dates, and (b) allowing each image to generate its own spectral signature. This study investigates the use of temporally invariant calibration and validation data to map land-cover in Massachusetts, employing five satellite images collected from five separate dates and different sensors. The results indicate that this technique …