Derivation of Solar Insolation Estimates from LiDAR

This Honors Thesis describes the methodology that was used from May 2010 to December 2010 for deriving solar insolation estimates for the University of Colorado at Boulder campus from Light Detection And Ranging (LiDAR) data. Background is given on the LiDAR data set used, including acquisition considerations and the properties of the data set itself. The primary method used to derive solar insolation estimates of campus was the generation of first-return canopy Digital Elevation Models (DEMs) using ENVI, followed by slope and aspect calculations using the open-source Geographic Information System (GIS) GRASS. The slope and aspect raster tiles were used to derive solar insolation estimates using the r.sun GRASS module, and an extraction of campus building rooftops was accomplished using existing vector campus GIS data sets. The reasons and constraints that led to the development of this methodology are discussed and possible sources of error are considered. Finally, the findings and implications of this study are presented and additional steps to reduce error in future work are explored

Improved surface temperature estimates with MASTER / AVIRIS sensor fusion

Land surface temperature (LST) is an important parameter in many ecological studies, where processes such as evapotranspiration have impacts at temperature gradients less than 1 K. The current Root Mean Square Errors (RMSE) in standard MODIS and ASTER LST products are greater than 1 K, and for ASTER can be as large as 4 K for graybody pixels such as vegetation. Errors of 3 to 8 K have been observed for ASTER in humid conditions, making knowledge of atmospheric water vapor content critical in retrieving accurate LST. For this reason improved accuracy in LST measurements through the synthesis of visible-to-shortwave-infrared (VSWIR) derived water vapor maps and Thermal-Infrared (TIR) data is one goal of the Hyperspectral Infrared Imager, or HyspIRI, mission. The 2011 ER-2 Delano/Lost Hills flights acquired data with both the MODIS/ASTER Simulator (MASTER) and Airborne Visible InfraRed Imaging Spectrometer (AVIRIS) instruments flown concurrently. This study compares LST retrieval accuracies from the standard JPL MASTER temperature products produced using the Temperature Emissivity Separation (TES) algorithm, and the Water Vapor Scaling (WVS) atmospheric correction method proposed for HyspIRI. The two retrieval methods are run both with and without high spatial resolution AVIRIS-derived water vapor maps to assess the improvement from VSWIR synthesis. We find improvement using VSWIR derived water vapor maps in both cases, with the WVS method being most accurate overall. For closed canopy agricultural vegetation we observed canopy temperature retrieval RMSEs of 0.49 K and 0.70 K using the WVS method on MASTER data with and without AVIRIS derived water vapor,respectively

Track: Teaching Political Theory and Theories

The 2011 Teaching Political Theory and Theories track drew scholars from Europe and the United States and featured work from political scientists representing the four major subfields. While analyzing the nine papers presented, participants articulated a range of perspectives on questions of pedagogy and the relationship between political theory and political science; indeed, the variety of perspectives confirmed the ongoing contestability of many central concepts in both the scholarship of teaching and learning (SOTAL) and the discipline of political science.Whether discussing ways to develop assignments for undergraduate research projects on the Tea Party or how to employ insights from deliberative democratic theory to assess the role of education in addressing racial violence in the United States, participants confronted important questions regarding the role of theory in the discipline, the broadening of undergraduate and graduate teaching strategies, and assessment of the effectiveness of alternative teaching strategies

Cascading lake drainage on the Greenland Ice Sheet triggered by tensile shock and fracture

Supraglacial lakes on the Greenland Ice Sheet are expanding inland, but the impact on ice flow is equivocal because interior surface conditions may preclude the transfer of surface water to the bed. Here we use a well-constrained 3D model to demonstrate that supraglacial lakes in Greenland drain when tensile-stress perturbations propagate fractures in areas where fractures are normally absent or closed. These melt-induced perturbations escalate when lakes as far as 80?km apart form expansive networks and drain in rapid succession. The result is a tensile shock that establishes new surface-to-bed hydraulic pathways in areas where crevasses transiently open. We show evidence for open crevasses 135?km inland from the ice margin, which is much farther inland than previously considered possible. We hypothesise that inland expansion of lakes will deliver water and heat to isolated regions of the ice sheet?s interior where the impact on ice flow is potentially largepublishersversionPeer reviewe

Greenland Surface Roughness Retrieval and Status

Crevasses are important hydrologic conduits that evacuate surface melt water from the ice sheet, impacting glacier dynamics and contributing to global sea level rise. This thesis describes a novel processing pipeline for retrieving likely crevasse locations from ICESat waveform returns, and demonstrates the methodology over a large land terminating drainage basin of the southwest Greenland ice sheet. This method is then extended and applied to the ice sheet periphery, and validated against optical imagery derived crevasse observations. The dataset described herein provides the earliest (years 2004 - 2006) baseline assessment of crevasse occurrence throughout the Greenland ice sheet periphery, and is a crucial comparison point for the ICESat-2 mission in assessing decadal length changes over the region. I find robust evidence of crevassing 135km inland at heights above 1800 meters, with weaker indications of surface anomalies occurring even higher on the ice sheet (up to 2300 meters). In addition, I provide both climatological (melt, runoff, surface mass balance), and mechanistic (strain, temperature, slope, thickness) parameter space distributions of crevassed areas. The distribution of crevasses suggests that in a warming climate, the ice sheet will have the potential to route water to englacial hydrologic systems at much higher elevations than previously thought, and could indicate significant ice sheet vulnerability in increasingly intense melt years. The spatial distribution of crevasses are highly coincident with ice lenses, and possibly exclusive of firn aquifers– a finding that could inform the distribution of crevasses through a range of climatological warming scenarios

A context sensitive, advisory decision support approach for mobile, knowledge based, time critical environments

This research aimed to explore decision support in mobile, knowledge based, time critical environments involving ill-defined decision situations. The research was concerned with how decision makers in such environments made their decisions and whether/how the decision making process could be supported by knowledge based decision support technology. The aim presented within the thesis is to ascertain the necessary components of a decision support system capable of incorporating contextual knowledge, real time context modelling and providing useful decision support for ill-defined decision situations. A design science research methodology was adopted for the research. This methodology incorporated researching the domain, knowledge acquisition, artefact development in the form of a prototype, and a qualitative evaluation of the system's feasibility and potential usefulness in a particular context. The research utilised decision support, mobile technology and knowledge acquisition concepts, and of particular importance, the areas of context sensitive decision support and advisory systems to develop the prototype. This research developed a new approach towards decision support within the target problem domain. This approach involved utilising context sensitive decision support techniques to represent expert knowledge in a generalised form. This knowledge was then incorporated within a mobile advisory system prototype to address the time critical nature of the target domain. Hospital triage was selected as an example of the time critical problem domain. Expert knowledge was obtained from triage nurses, which was not otherwise detailed in official triage documentation. The prototype system was developed to explore the implementation of the approach and acquired knowledge. Triage nurses were also involved in a qualitative evaluation of the prototype mobile decision support system. The evaluation was aimed at establishing the importance of the contextual components of the system and its suitability within the triage environment. Feedback from the evaluation suggested domain experts' approval of this form of decision support. Comments issued indicate decision support in this form could be of benefit for triage nurses to support their decisions with specific experiential knowledge. The domain experts also indicated that this form of support would be most beneficial for trainee triage nurses whose lack of experience necessitates additional guidance. Another potential application was suggested for the purpose of education of staff in specific knowledge of medical triage. This research contributes to the theory and practice of development of knowledge based mobile decision support systems within such domains where domain knowledge is critical but not well documented. The implementation of generalised guiding contextual rules was found to be useful within a mobile and time critical environment involving ill-defined decision situations. The generalised contextual rules provided safe decision support and in a form that would have minimal impact on the time taken to make decisions. The key concepts within the system which addressed the research questions are generalised contextual rules, context management objects, and an interface that presents guiding information to address time constraints in mobile decision support environment

Cascading lake drainage on the Greenland Ice Sheet triggered by tensile shock and fracture

Supraglacial lakes on the Greenland Ice Sheet are expanding inland, but the impact on ice flow is equivocal because interior surface conditions may preclude the transfer of surface water to the bed. Here we use a well-constrained 3D model to demonstrate that supraglacial lakes in Greenland drain when tensile-stress perturbations propagate fractures in areas where fractures are normally absent or closed. These melt-induced perturbations escalate when lakes as far as 80 km apart form expansive networks and drain in rapid succession. The result is a tensile shock that establishes new surface-to-bed hydraulic pathways in areas where crevasses transiently open. We show evidence for open crevasses 135 km inland from the ice margin, which much farther inland is than previously considered possible. We hypothesise that inland expansion of lakes will deliver water and heat to isolated regions of the ice sheet’s interior where the impact on ice flow is potentially larg