Science.gov

Sample records for agency complex terrain

  1. Turbulence measurements over complex terrain

    NASA Astrophysics Data System (ADS)

    Skupniewicz, Charles E.; Kamada, Ray F.; Schacher, Gordon E.

    1989-07-01

    Horizontal turbulence measurements obtained from 22 wind sensors located on 9 towers in a mountainous coastal area are described and categorized by stability and terrain. Vector wind time series are high-pass filtered, and lateral and longitudinal wind speed variance is calculated for averaging times ranging from 15 s to 2 h. Parameterizations of the functional dependence of variance on averaging time are discussed, and a modification of Panofsky's (1988) uniform terrain technique applicable to complex terrain is presented. The parameterization is applied to the data and shown to be more realistic than a less complicated power law technique. The parameter values are shown to be different than the flat terrain cases of Kaimal et al. (1972), and are primarily a function of sensor location within the complex terrain. The parameters are also examined in terms of their dependence upon season, stability, marine boundary-layer height, and measurement height.

  2. Stably stratified canopy flow in complex terrain

    NASA Astrophysics Data System (ADS)

    Xu, X.; Yi, C.; Kutter, E.

    2014-11-01

    The characteristics of stably stratified canopy flows in complex terrain are investigated by employing the Renormalized Group (RNG) k-ɛ turbulence model. In this two-dimensional simulation, we imposed persistent constant heat flux at ground surface and linearly increasing cooling rate in the upper canopy layer, vertically varying dissipative force from canopy drag elements, buoyancy forcing induced from thermal stratification and the hill terrain. These strong boundary effects keep nonlinearity in the two-dimensional Navier-Stokes equations high enough to generate turbulent behavior. The fundamental characteristics of nighttime canopy flow over complex terrain measured by a few multi-tower advection experiments can be produced by this numerical simulation, such as: (1) unstable layer in the canopy, (2) super-stable layer associated with flow decoupling in deep canopy and near the top of canopy, (3) upward momentum transfer in canopy, and (4) large buoyancy suppression and weak shear production in strong stability.

  3. Modelling Canopy Flows over Complex Terrain

    NASA Astrophysics Data System (ADS)

    Grant, Eleanor R.; Ross, Andrew N.; Gardiner, Barry A.

    2016-06-01

    Recent studies of flow over forested hills have been motivated by a number of important applications including understanding CO_2 and other gaseous fluxes over forests in complex terrain, predicting wind damage to trees, and modelling wind energy potential at forested sites. Current modelling studies have focussed almost exclusively on highly idealized, and usually fully forested, hills. Here, we present model results for a site on the Isle of Arran, Scotland with complex terrain and heterogeneous forest canopy. The model uses an explicit representation of the canopy and a 1.5-order turbulence closure for flow within and above the canopy. The validity of the closure scheme is assessed using turbulence data from a field experiment before comparing predictions of the full model with field observations. For near-neutral stability, the results compare well with the observations, showing that such a relatively simple canopy model can accurately reproduce the flow patterns observed over complex terrain and realistic, variable forest cover, while at the same time remaining computationally feasible for real case studies. The model allows closer examination of the flow separation observed over complex forested terrain. Comparisons with model simulations using a roughness length parametrization show significant differences, particularly with respect to flow separation, highlighting the need to explicitly model the forest canopy if detailed predictions of near-surface flow around forests are required.

  4. Carbon dioxide transport over complex terrain

    USGS Publications Warehouse

    Sun, Jielun; Burns, Sean P.; Delany, A.C.; Oncley, S.P.; Turnipseed, A.; Stephens, B.; Guenther, A.; Anderson, D.E.; Monson, R.

    2004-01-01

    The nocturnal transport of carbon dioxide over complex terrain was investigated. The high carbon dioxide under very stable conditions flows to local low-ground. The regional drainage flow dominates the carbon dioxide transport at the 6 m above the ground and carbon dioxide was transported to the regional low ground. The results show that the local drainage flow was sensitive to turbulent mixing associated with local wind shear.

  5. Stably stratified canopy flow in complex terrain

    NASA Astrophysics Data System (ADS)

    Xu, X.; Yi, C.; Kutter, E.

    2015-07-01

    Stably stratified canopy flow in complex terrain has been considered a difficult condition for measuring net ecosystem-atmosphere exchanges of carbon, water vapor, and energy. A long-standing advection error in eddy-flux measurements is caused by stably stratified canopy flow. Such a condition with strong thermal gradient and less turbulent air is also difficult for modeling. To understand the challenging atmospheric condition for eddy-flux measurements, we use the renormalized group (RNG) k-ϵ turbulence model to investigate the main characteristics of stably stratified canopy flows in complex terrain. In this two-dimensional simulation, we imposed persistent constant heat flux at ground surface and linearly increasing cooling rate in the upper-canopy layer, vertically varying dissipative force from canopy drag elements, buoyancy forcing induced from thermal stratification and the hill terrain. These strong boundary effects keep nonlinearity in the two-dimensional Navier-Stokes equations high enough to generate turbulent behavior. The fundamental characteristics of nighttime canopy flow over complex terrain measured by the small number of available multi-tower advection experiments can be reproduced by this numerical simulation, such as (1) unstable layer in the canopy and super-stable layers associated with flow decoupling in deep canopy and near the top of canopy; (2) sub-canopy drainage flow and drainage flow near the top of canopy in calm night; (3) upward momentum transfer in canopy, downward heat transfer in upper canopy and upward heat transfer in deep canopy; and (4) large buoyancy suppression and weak shear production in strong stability.

  6. Wind modelling over complex terrain using CFD

    NASA Astrophysics Data System (ADS)

    Avila, Matias; Owen, Herbert; Folch, Arnau; Prieto, Luis; Cosculluela, Luis

    2015-04-01

    The present work deals with the numerical CFD modelling of onshore wind farms in the context of High Performance Computing (HPC). The CFD model involves the numerical solution of the Reynolds-Averaged Navier-Stokes (RANS) equations together with a κ-ɛ turbulence model and the energy equation, specially designed for Atmospheric Boundary Layer (ABL) flows. The aim is to predict the wind velocity distribution over complex terrain, using a model that includes meteorological data assimilation, thermal coupling, forested canopy and Coriolis effects. The modelling strategy involves automatic mesh generation, terrain data assimilation and generation of boundary conditions for the inflow wind flow distribution up to the geostrophic height. The CFD model has been implemented in Alya, a HPC multi physics parallel solver able to run with thousands of processors with an optimal scalability, developed in Barcelona Supercomputing Center. The implemented thermal stability and canopy physical model was developed by Sogachev in 2012. The k-ɛ equations are of non-linear convection diffusion reaction type. The implemented numerical scheme consists on a stabilized finite element formulation based on the variational multiscale method, that is known to be stable for this kind of turbulence equations. We present a numerical formulation that stresses on the robustness of the solution method, tackling common problems that produce instability. The iterative strategy and linearization scheme is discussed. It intends to avoid the possibility of having negative values of diffusion during the iterative process, which may lead to divergence of the scheme. These problems are addressed by acting on the coefficients of the reaction and diffusion terms and on the turbulent variables themselves. The k-ɛ equations are highly nonlinear. Complex terrain induces transient flow instabilities that may preclude the convergence of computer flow simulations based on steady state formulation of the

  7. Spectra over complex terrain in the surface layer

    SciTech Connect

    Panofsky, H.A.; Dutton, J.A.; Larko, D.; Lipschutz, R.; Stone, G.

    1982-09-01

    For design and control of Wind Energy Conversion Systems (WECS), the spectral distribution of wind speeds over frequencies needs to be known as well as velocity variances. Velocity spectra and other velocity statistics are estimated over three types of complex terrain: on tops of hills or escarpments; on land a short distance downwind from a water body; and over rolling farm land. The most important characteristics of turbulence models over uniform terrain are summarized briefly. Theoretical aspects of spectral characteristics over complex terrain are discussed, followed by detailed observations over complex terrain and procedures for their estimation. A theory is presented for calculation of response of engineering systems to wind fluctuations. (LEW)

  8. Three dimensional fog forecasting in complex terrain

    NASA Astrophysics Data System (ADS)

    Mueller, M.; Masbou, M.; Bott, A.

    2010-07-01

    Fog in complex terrain shows large temporal and spatial variations that can only be simulated with a three-dimensional model, but more modifications than increasing the resolution are needed. For a better representation of fog we present a second moment cloud water scheme with a parametrization of the Köhler theory which is combined with the mixed phase Ferrier microphysics scheme. The more detailed microphysics produce many differences to the first moment Ferrier scheme and are responsible for reproducing the typically low liquid water content of fog. With explicitly predicted droplet number concentrations, sedimentation of cloud water can be modeled without a prescribed fall speed, which mainly affects the vertical distribution of cloud water and the end of the fogs life cycle. The complex topography of the Swiss Alps and its surroundings are used for model testing. As the focus is on the models ability to forecast the spatial distribution of fog, cloud patterns derived from high resolution MSG satellite data, rather than few point observations from ground stations are used. In a continous five day period of anticyclonic conditions, the satellite observed fog patterns showed large day to day variations with almost no fog to large areas of fog. This variability was very well simulated in the three-dimensional fog forecast. The simulations also demonstrate the need for high horizontal resolutions between 1 and 3 km. For model initialization the complex topography is actually a simplifying factor, as cold air flow and pooling are dominating the more uncertain processes of evapotranspiration or errors in the soil moisture field.

  9. Landscape structure controls on biogeochemical fluxes in complex terrain (Invited)

    NASA Astrophysics Data System (ADS)

    McGlynn, B. L.; Riveros-Iregui, D.; Emanuel, R. E.; Pacific, V. J.; Epstein, H. E.; Welsch, D. L.

    2010-12-01

    Complex topography, topology, and strong environmental gradients in mountainous terrain impart fundamental controls on the distribution and redistribution of water, energy, and nutrients across the landscape. Many of these variables exhibit spatial patterns influenced by landscape structure and hydrologically mediated redistribution processes. Landscape structure therefore can lead to organized heterogeneity of ecosystem dynamics because of the interplay between abiotic and biotic processes. Mountainous terrain can also experience large diel, seasonal and interannual fluctuations in hydrometeorology. These temporal fluctuations will manifest differently across the landscape due to strong biophysical gradients and redistribution processes less influential in more homogenous terrain. Investigation in complex terrain therefore can provide insight into processes and feedbacks among nutrients, water, and climate. Here we examine space-time variability in ecosystem processes at the catchment scale with focus on carbon cycle science. We highlight controls on soil respiration and stream DOC export from plots to watershed scales based on high spatial and temporal resolution observation, empirical and numerical modeling, and eddy covariance approaches. We suggest complex terrain imparts organization on observed heterogeneity that can be used to gain new understanding of fundamental controls on ecosystem processes.

  10. Modeling and Visualizing Flow of Chemical Agents Across Complex Terrain

    NASA Technical Reports Server (NTRS)

    Kao, David; Kramer, Marc; Chaderjian, Neal

    2005-01-01

    Release of chemical agents across complex terrain presents a real threat to homeland security. Modeling and visualization tools are being developed that capture flow fluid terrain interaction as well as point dispersal downstream flow paths. These analytic tools when coupled with UAV atmospheric observations provide predictive capabilities to allow for rapid emergency response as well as developing a comprehensive preemptive counter-threat evacuation plan. The visualization tools involve high-end computing and massive parallel processing combined with texture mapping. We demonstrate our approach across a mountainous portion of North California under two contrasting meteorological conditions. Animations depicting flow over this geographical location provide immediate assistance in decision support and crisis management.

  11. Biosphere-Atmosphere Fluxes in Complex Terrain: Challenges and Opportunities

    NASA Astrophysics Data System (ADS)

    Novick, K. A.; Oishi, A. C.; Brantley, S. T.; Miniat, C. F.; Walker, J. T.; Vose, J. M.

    2014-12-01

    The occurrence of advection fluxes in complex terrain complicates the interpretation of eddy covariance data. As a result, flux monitoring networks are biased towards flat, homogeneous ecosystems. Here, we discuss both the challenges and opportunities presented by efforts to quantify ecosystem mass and energy fluxes in topographically complex sites. An approach for characterizing advection fluxes that relies on data collected from a single tower is described and applied as a case study in a flux monitoring site located in complex and heterogeneous terrain at the Coweeta Hydrologic Laboratory (North Carolina, USA). This site experiences significant nocturnal advection of mass and energy driven by downslope drainage flows, and significant daytime horizontal advection driven by the effects of anabatic and katabatic flow regimes on the flux footprint. While the advection regime at Coweeta may be especially challenging, the approach presented here is also relevant for flatter and more homogeneous sites where advection fluxes may be small but nonetheless non-negligible. Having addressed the methodological challenges presented by advection flows, we discuss novel opportunities associated with efforts to monitor ecosystem fluxes in complex sites. In particular, data from Coweeta are leveraged to highlight how topography buffers the site from mesoscale hydro-climatic variability via its influence on precipitation inputs, air and soil temperature, and vapor pressure deficit. We conclude by stressing that advances in flux measurement methodology now permit flux observation campaigns in complex and heterogeneous sites; furthermore, such data may be quite useful for exploring links between terrain, micro-meteorology, and physiological functioning.

  12. (Relatively) Simple Models of Flow in Complex Terrain

    NASA Astrophysics Data System (ADS)

    Taylor, Peter; Weng, Wensong; Salmon, Jim

    2013-04-01

    The term, "complex terrain" includes both topography and variations in surface roughness and thermal properties. The scales that are affected can differ and there are some advantages to modeling them separately. In studies of flow in complex terrain we have developed 2 D and 3 D models of atmospheric PBL boundary layer flow over roughness changes, appropriate for longer fetches than most existing models. These "internal boundary layers" are especially important for understanding and predicting wind speed variations with distance from shorelines, an important factor for wind farms around, and potentially in, the Great Lakes. The models can also form a base for studying the wakes behind woodlots and wind turbines. Some sample calculations of wind speed evolution over water and the reduced wind speeds behind an isolated woodlot, represented simply in terms of an increase in surface roughness, will be presented. Note that these models can also include thermal effects and non-neutral stratification. We can use the model to deal with 3-D roughness variations and will describe applications to both on-shore and off-shore situations around the Great Lakes. In particular we will show typical results for hub height winds and indicate the length of over-water fetch needed to get the full benefit of siting turbines over water. The linear Mixed Spectral Finite-Difference (MSFD) and non-linear (NLMSFD) models for surface boundary-layer flow over complex terrain have been extended to planetary boundary-layer flow over topography This allows for their use for larger scale regions and increased heights. The models have been applied to successfully simulate the Askervein hill experimental case and we will show examples of applications to more complex terrain, typical of some Canadian wind farms. Output from the model can be used as an alternative to MS-Micro, WAsP or other CFD calculations of topographic impacts for input to wind farm design software.

  13. Field Observations of Canopy Flows over Complex Terrain

    NASA Astrophysics Data System (ADS)

    Grant, Eleanor R.; Ross, Andrew N.; Gardiner, Barry A.; Mobbs, Stephen D.

    2015-08-01

    The investigation of airflow over and within forests in complex terrain has been, until recently, limited to a handful of modelling and laboratory studies. Here, we present an observational dataset of airflow measurements inside and above a forest situated on a ridge on the Isle of Arran, Scotland. The spatial coverage of the observations all the way across the ridge makes this a unique dataset. Two case studies of across-ridge flow under near-neutral conditions are presented and compared with recent idealized two-dimensional modelling studies. Changes in the canopy profiles of both mean wind and turbulent quantities across the ridge are broadly consistent with these idealized studies. Flow separation over the lee slope is seen as a ubiquitous feature of the flow. The three-dimensional nature of the terrain and the heterogeneous forest canopy does however lead to significant variations in the flow separation across the ridge, particularly over the less steep western slope. Furthermore, strong directional shear with height in regions of flow separation has a significant impact on the Reynolds stress terms and other turbulent statistics. Also observed is a decrease in the variability of the wind speed over the summit and lee slope, which has not been seen in previous studies. This dataset should provide a valuable resource for validating models of canopy flow over real, complex terrain.

  14. Wind tunnel studies of gas dispersion over complex terrain

    NASA Astrophysics Data System (ADS)

    Michálek, Petr; Zacho, David

    2016-03-01

    Wind tunnel studies of gas dispersion over complex terrain model were performed in VZLU Prague. The terrain model with a ground-level emission source was mounted in a boundary layer wind tunnel. Flow and concentration field behind the source was measured. The model presented an area of the Liberec city, 9.0 × 2.4 km in full scale. The emission source was mounted at the position of a heating plant in the model centre and concentration field was measured using flame ionisation detectors. The experimental results will be used for validation and verification of a new computational dispersion model intended for use in case of accidents with dangerous gas leakages in selected areas in Czech Republic.

  15. Atmospheric transport in complex terrain at Los Alamos, Area G

    SciTech Connect

    Vold, E.L.

    1997-03-01

    This report documents the atmospheric dispersion used in the Area G Performance Assessment for off-site airborne dose calculations. Potential airborne contaminants from the mesa top disposal facility disperse in the complex terrain dominated by narrow mesas in parallel to narrow canyons. The dispersion is characterized by site-specific values of X/Q [(Ci/m{sup 3})/(Ci/s)] at each of two designated receptor locations, a {open_quote}maximum off-site dose{close_quote} location and a nearby population center (White Rock, NM). The values of X/Q in each of the sixteen wind sectors are first estimated with the CAP-88 computer code using 1992 annual meteorologic data from Area G and assuming an area source for release. This data captures the dominant wind direction on the mesa tops from the SSW. These dispersion parameters are assumed to apply to open, flat terrain and must be corrected for the complex mesa and canyon terrain terrain surrounding the Area G site. Additional meteorologic data has been collected over two years from six remote temporary meteorological stations operated on the mesas and in the canyons immediately around Area G. These data indicate that the wind flow in the canyons is exclusively bimodel, flowing up canyon during the day and down canyon at night. It is conservatively assumed that all ground level releases from Area G which blow out across an adjacent canyon become entrained in the canyon flow. This effectively combines the contaminant release for several sectors into a single canyon flow which is upstream during the day or downstream at night. This canyon channeling mechanism is implemented in the model by summing the wind sector dispersion factors over those sectors appropriate to the geometry for a release from Area G toward either adjacent canyon.

  16. Evaluation of terrain complexity by autocorrelation. [geomorphology and geobotany

    NASA Technical Reports Server (NTRS)

    Craig, R. G.

    1982-01-01

    The topographic complexity of various sections of the Ozark, Appalachian, and Interior Low Plateaus, as well as of the New England, Piedmont, Blue Ridge, Ouachita, and Valley and Ridge Provinces of the Eastern United States were characterized. The variability of autocorrelation within a small area (7 1/2-ft quadrangle) to the variability at widely separated and diverse areas within the same physiographic region was compared to measure the degree of uniformity of the processes which can be expected to be encountered within a given physiographic province. The variability of autocorrelation across the eight geomorphic regions was compared and contrasted. The total study area was partitioned into subareas homogeneous in terrain complexity. The relation between the complexity measured, the geomorphic process mix implied, and the way in which geobotanical information is modified into a more or less recognizable entity is demonstrated. Sampling strategy is described.

  17. Visual control of foot placement when walking over complex terrain.

    PubMed

    Matthis, Jonathan S; Fajen, Brett R

    2014-02-01

    The aim of this study was to investigate the role of visual information in the control of walking over complex terrain with irregularly spaced obstacles. We developed an experimental paradigm to measure how far along the future path people need to see in order to maintain forward progress and avoid stepping on obstacles. Participants walked over an array of randomly distributed virtual obstacles that were projected onto the floor by an LCD projector while their movements were tracked by a full-body motion capture system. Walking behavior in a full-vision control condition was compared with behavior in a number of other visibility conditions in which obstacles did not appear until they fell within a window of visibility centered on the moving observer. Collisions with obstacles were more frequent and, for some participants, walking speed was slower when the visibility window constrained vision to less than two step lengths ahead. When window sizes were greater than two step lengths, the frequency of collisions and walking speed were weakly affected or unaffected. We conclude that visual information from at least two step lengths ahead is needed to guide foot placement when walking over complex terrain. When placed in the context of recent research on the biomechanics of walking, the findings suggest that two step lengths of visual information may be needed because it allows walkers to exploit the passive mechanical forces inherent to bipedal locomotion, thereby avoiding obstacles while maximizing energetic efficiency.

  18. Intelligent mobility research for robotic locomotion in complex terrain

    NASA Astrophysics Data System (ADS)

    Trentini, Michael; Beckman, Blake; Digney, Bruce; Vincent, Isabelle; Ricard, Benoit

    2006-05-01

    The objective of the Autonomous Intelligent Systems Section of Defence R&D Canada - Suffield is best described by its mission statement, which is "to augment soldiers and combat systems by developing and demonstrating practical, cost effective, autonomous intelligent systems capable of completing military missions in complex operating environments." The mobility requirement for ground-based mobile systems operating in urban settings must increase significantly if robotic technology is to augment human efforts in these roles and environments. The intelligence required for autonomous systems to operate in complex environments demands advances in many fields of robotics. This has resulted in large bodies of research in areas of perception, world representation, and navigation, but the problem of locomotion in complex terrain has largely been ignored. In order to achieve its objective, the Autonomous Intelligent Systems Section is pursuing research that explores the use of intelligent mobility algorithms designed to improve robot mobility. Intelligent mobility uses sensing, control, and learning algorithms to extract measured variables from the world, control vehicle dynamics, and learn by experience. These algorithms seek to exploit available world representations of the environment and the inherent dexterity of the robot to allow the vehicle to interact with its surroundings and produce locomotion in complex terrain. The primary focus of the paper is to present the intelligent mobility research within the framework of the research methodology, plan and direction defined at Defence R&D Canada - Suffield. It discusses the progress and future direction of intelligent mobility research and presents the research tools, topics, and plans to address this critical research gap. This research will create effective intelligence to improve the mobility of ground-based mobile systems operating in urban settings to assist the Canadian Forces in their future urban operations.

  19. Wind Power Curve Modeling in Simple and Complex Terrain

    SciTech Connect

    Bulaevskaya, V.; Wharton, S.; Irons, Z.; Qualley, G.

    2015-02-09

    Our previous work on wind power curve modeling using statistical models focused on a location with a moderately complex terrain in the Altamont Pass region in northern California (CA). The work described here is the follow-up to that work, but at a location with a simple terrain in northern Oklahoma (OK). The goal of the present analysis was to determine the gain in predictive ability afforded by adding information beyond the hub-height wind speed, such as wind speeds at other heights, as well as other atmospheric variables, to the power prediction model at this new location and compare the results to those obtained at the CA site in the previous study. While we reach some of the same conclusions at both sites, many results reported for the CA site do not hold at the OK site. In particular, using the entire vertical profile of wind speeds improves the accuracy of wind power prediction relative to using the hub-height wind speed alone at both sites. However, in contrast to the CA site, the rotor equivalent wind speed (REWS) performs almost as well as the entire profile at the OK site. Another difference is that at the CA site, adding wind veer as a predictor significantly improved the power prediction accuracy. The same was true for that site when air density was added to the model separately instead of using the standard air density adjustment. At the OK site, these additional variables result in no significant benefit for the prediction accuracy.

  20. Complex geomorphologic assemblage of terrains in association with the banded terrain in Hellas basin, Mars

    NASA Astrophysics Data System (ADS)

    Diot, X.; El-Maarry, M. R.; Schlunegger, F.; Norton, K. P.; Thomas, N.; Grindrod, P. M.; Chojnacki, M.

    2016-02-01

    Hellas basin acts as a major sink for the southern highlands of Mars and is likely to have recorded several episodes of sedimentation and erosion. The north-western part of the basin displays a potentially unique Amazonian landscape domain in the deepest part of Hellas, called "banded terrain", which is a deposit characterized by an alternation of narrow band shapes and inter-bands displaying a sinuous and relatively smooth surface texture suggesting a viscous flow origin. Here we use high-resolution (HiRISE and CTX) images to assess the geomorphological interaction of the banded terrain with the surrounding geomorphologic domains in the NW interior of Hellas to gain a better understanding of the geological evolution of the region as a whole. Our analysis reveals that the banded terrain is associated with six geomorphologic domains: a central plateau named Alpheus Colles, plain deposits (P1 and P2), reticulate (RT1 and RT2) and honeycomb terrains. Based on the analysis of the geomorphology of these domains and their cross-cutting relationships, we show that no widespread deposition post-dates the formation of the banded terrain, which implies that this domain is the youngest and latest deposit of the interior of Hellas. Therefore, the level of geologic activity in the NW Hellas during the Amazonian appears to have been relatively low and restricted to modification of the landscape through mechanical weathering, aeolian and periglacial processes. Thermophysical data and cross-cutting relationships support hypotheses of modification of the honeycomb terrain via vertical rise of diapirs such as ice diapirism, and the formation of the plain deposits through deposition and remobilization of an ice-rich mantle deposit. Finally, the observed gradual transition between honeycomb and banded terrain suggests that the banded terrain may have covered a larger area of the NW interior of Hellas in the past than previously thought. This has implications on the understanding of

  1. Analyzing complex wake-terrain interactions and its implications on wind-farm performance.

    NASA Astrophysics Data System (ADS)

    Tabib, Mandar; Rasheed, Adil; Fuchs, Franz

    2016-09-01

    Rotating wind turbine blades generate complex wakes involving vortices (helical tip-vortex, root-vortex etc.).These wakes are regions of high velocity deficits and high turbulence intensities and they tend to degrade the performance of down-stream turbines. Hence, a conservative inter-turbine distance of up-to 10 times turbine diameter (10D) is sometimes used in wind-farm layout (particularly in cases of flat terrain). This ensures that wake-effects will not reduce the overall wind-farm performance, but this leads to larger land footprint for establishing a wind-farm. In-case of complex-terrain, within a short distance (say 10D) itself, the nearby terrain can rise in altitude and be high enough to influence the wake dynamics. This wake-terrain interaction can happen either (a) indirectly, through an interaction of wake (both near tip vortex and far wake large-scale vortex) with terrain induced turbulence (especially, smaller eddies generated by small ridges within the terrain) or (b) directly, by obstructing the wake-region partially or fully in its flow-path. Hence, enhanced understanding of wake- development due to wake-terrain interaction will help in wind farm design. To this end the current study involves: (1) understanding the numerics for successful simulation of vortices, (2) understanding fundamental vortex-terrain interaction mechanism through studies devoted to interaction of a single vortex with different terrains, (3) relating influence of vortex-terrain interactions to performance of a wind-farm by studying a multi-turbine wind-farm layout under different terrains. The results on interaction of terrain and vortex has shown a much faster decay of vortex for complex terrain compared to a flatter-terrain. The potential reasons identified explaining the observation are (a) formation of secondary vortices in flow and its interaction with the primary vortex and (b) enhanced vorticity diffusion due to increased terrain-induced turbulence. The implications of

  2. Numerical simulation of radiation fog in complex terrain

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Musson-Genon, L.; Carissimo, B.; Dupont, E.

    2009-09-01

    The interest for micro-scale modeling of the atmosphere is growing for environmental applications related, for example, to energy production, transport and urban development. The turbulence in the stable layers where pollutant dispersion is low and can lead to strong pollution events. This could be further complicated by the presence of clouds or fog and is specifically difficult in urban or industrial area due to the presence of buildings. In this context, radiation fog formation and dissipation over complex terrain were therefore investigated with a state-of-the-art model. This study is divided into two phases. The first phase is a pilot stage, which consist of employing a database from the ParisFog campaign which took place in the south of Paris during winter 2006-07 to assess the ability of the cloud model to reproduce the detailed structure of radiation fog. The second phase use the validated model for the study of influence of complex terrain on fog evolution. Special attention is given to the detailed and complete simulations and validation technique used is to compare the simulated results using the 3D cloud model of computational fluid dynamical software Code_Saturne with one of the best collected in situ data during the ParisFog campaign. Several dynamical, microphysical parameterizations and simulation conditions have been described. The resulting 3D cloud model runs at a horizontal resolution of 30 m and a vertical resolution comparable to the 1D model. First results look very promising and are able to reproduce the spatial distribution of fog. The analysis of the behavior of the different parameterized physical processes suggests that the subtle balance between the various processes is achieved.

  3. Objective high Resolution Analysis over Complex Terrain with VERA

    NASA Astrophysics Data System (ADS)

    Mayer, D.; Steinacker, R.; Steiner, A.

    2012-04-01

    VERA (Vienna Enhanced Resolution Analysis) is a model independent, high resolution objective analysis of meteorological fields over complex terrain. This system consists of a special developed quality control procedure and a combination of an interpolation and a downscaling technique. Whereas the so called VERA-QC is presented at this conference in the contribution titled "VERA-QC, an approved Data Quality Control based on Self-Consistency" by Andrea Steiner, this presentation will focus on the method and the characteristics of the VERA interpolation scheme which enables one to compute grid point values of a meteorological field based on irregularly distributed observations and topography related aprior knowledge. Over a complex topography meteorological fields are not smooth in general. The roughness which is induced by the topography can be explained physically. The knowledge about this behavior is used to define the so called Fingerprints (e.g. a thermal Fingerprint reproducing heating or cooling over mountainous terrain or a dynamical Fingerprint reproducing positive pressure perturbation on the windward side of a ridge) under idealized conditions. If the VERA algorithm recognizes patterns of one or more Fingerprints at a few observation points, the corresponding patterns are used to downscale the meteorological information in a greater surrounding. This technique allows to achieve an analysis with a resolution much higher than the one of the observational network. The interpolation of irregularly distributed stations to a regular grid (in space and time) is based on a variational principle applied to first and second order spatial and temporal derivatives. Mathematically, this can be formulated as a cost function that is equivalent to the penalty function of a thin plate smoothing spline. After the analysis field has been divided into the Fingerprint components and the unexplained part respectively, the requirement of a smooth distribution is applied to the

  4. Atmospheric studies in complex terrain: a planning guide for future studies

    SciTech Connect

    Orgill, M.M.

    1981-02-01

    The objective of this study is to assist the US Department of Energy in Conducting its atmospheric studies in complex terrain (ASCOT0 by defining various complex terrain research systems and relating these options to specific landforms sites. This includes: (1) reviewing past meteorological and diffusion research on complex terrain; (2) relating specific terrain-induced airflow phenomena to specific landforms and time and space scales; (3) evaluating the technical difficulty of modeling and measuring terrain-induced airflow phenomena; and (4) avolving severdal research options and proposing candidate sites for continuing and expanding field and modeling work. To evolve research options using variable candidate sites, four areas were considered: site selection, terrain uniqueness and quantification, definition of research problems and research plans. 36 references, 111 figures, 20 tables.

  5. A statistical analysis of icing prediction in complex terrains

    NASA Astrophysics Data System (ADS)

    Terborg, Amanda M.

    The issue of icing has been around for decades in aviation industry, and while notable improvements have been made in the study of the formation and process of icing, the prediction of icing events is a challenge that has yet to be completely overcome. Low level icing prediction, particularly in complex terrain, has been bumped to the back burner in an attempt to perfect the models created for in-flight icing. However, over the years there have been a number of different, non-model methods used to better refine the variable involved in low-level icing prediction. One of those methods comes through statistical analysis and modeling, particularly through the use of the Classification and Regression Tree (CART) techniques. These techniques examine the statistical significance of each predictor within a data set to determine various decision rules. Those rules in which the overall misclassification error is the smallest are then used to construct a decision tree and can be used to create a forecast for icing events. Using adiabatically adjusted Rapid Update Cycle (RUC) interpolated sounding data these CART techniques are used in this study to examine icing events in the White Mountains of New Hampshire, specifically on the summit of Mount Washington. The Mount Washington Observatory (MWO), which sits on the summit and is manned year around by weather observers, is no stranger to icing occurrences. In fact, the summit sees icing events from October all the way until April, and occasionally even into May. In this study, these events are examined in detail for the October 2010 to April 2011 season, and five CART models generated for icing in general, rime icing, and glaze icing in attempt to create a decision tree or trees with a high predictive accuracy. Also examined in this study for the October 2010 to April 2011 icing season is the Air Weather Service Pamphlet (AWSP) algorithm, a decision tree model currently in use by the Air Force to predict icing events. Producing

  6. Use of CALPUFF for exposure assessment in a near-field, complex terrain setting

    NASA Astrophysics Data System (ADS)

    MacIntosh, David L.; Stewart, James H.; Myatt, Theodore A.; Sabato, Joseph E.; Flowers, George C.; Brown, Kirk W.; Hlinka, Dennis J.; Sullivan, David A.

    2010-01-01

    CALPUFF is an atmospheric source-receptor model recommended by the U.S. Environmental Protection Agency for use on a case-by-case basis in complex terrain and wind conditions. The ability of the model to provide useful information for exposure assessments in areas with those topographical and meteorological conditions has received little attention. This is an important knowledge gap for use of CALPUFF outside of regulatory applications, such as exposure analyses conducted in support of risk assessments and health studies. We compared deposition of cadmium (Cd), lead (Pb), and zinc (Zn) calculated with CALPUFF as a result of emissions from a zinc smelter with corresponding concentrations of the metals measured in attic dust and soil samples obtained from the surrounding area. On a point-by-point analysis, predictions from CALPUFF explained 11% (lead) to 53% (zinc) of the variability in concentrations measured in attic dust. Levels of heavy metals in soil interpolated to 100 residential addresses from the distribution of concentrations measured in soil samples also agreed well with deposition predicted with CALPUFF: R2 of 0.46, 0.76, and 079 for Pb, Cd, and Zn, respectively. Community-average concentrations of Cd, Pb, and Zn measured in soil were significantly ( p < 0.0001) and strongly correlated ( R2 ranged from 0.77 to 0.98) with predicted deposition rates. These findings demonstrate that CALPUFF can provide reasonably accurate predictions of the patterns of long-term air pollutant deposition in the near-field associated with emissions from a discrete source in complex terrain. Because deposition estimates are calculated as a linear function of air concentrations, CALPUFF is expected to be reliable model for prediction of long-term average, near-field ambient air concentrations in complex terrain as well.

  7. Atmospheric dispersion modelling over complex terrain at small scale

    NASA Astrophysics Data System (ADS)

    Nosek, S.; Janour, Z.; Kukacka, L.; Jurcakova, K.; Kellnerova, R.; Gulikova, E.

    2014-03-01

    Previous study concerned of qualitative modelling neutrally stratified flow over open-cut coal mine and important surrounding topography at meso-scale (1:9000) revealed an important area for quantitative modelling of atmospheric dispersion at small-scale (1:3300). The selected area includes a necessary part of the coal mine topography with respect to its future expansion and surrounding populated areas. At this small-scale simultaneous measurement of velocity components and concentrations in specified points of vertical and horizontal planes were performed by two-dimensional Laser Doppler Anemometry (LDA) and Fast-Response Flame Ionization Detector (FFID), respectively. The impact of the complex terrain on passive pollutant dispersion with respect to the prevailing wind direction was observed and the prediction of the air quality at populated areas is discussed. The measured data will be used for comparison with another model taking into account the future coal mine transformation. Thus, the impact of coal mine transformation on pollutant dispersion can be observed.

  8. Power Curve Modeling in Complex Terrain Using Statistical Models

    NASA Astrophysics Data System (ADS)

    Bulaevskaya, V.; Wharton, S.; Clifton, A.; Qualley, G.; Miller, W.

    2014-12-01

    Traditional power output curves typically model power only as a function of the wind speed at the turbine hub height. While the latter is an essential predictor of power output, wind speed information in other parts of the vertical profile, as well as additional atmospheric variables, are also important determinants of power. The goal of this work was to determine the gain in predictive ability afforded by adding wind speed information at other heights, as well as other atmospheric variables, to the power prediction model. Using data from a wind farm with a moderately complex terrain in the Altamont Pass region in California, we trained three statistical models, a neural network, a random forest and a Gaussian process model, to predict power output from various sets of aforementioned predictors. The comparison of these predictions to the observed power data revealed that considerable improvements in prediction accuracy can be achieved both through the addition of predictors other than the hub-height wind speed and the use of statistical models. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344 and was funded by Wind Uncertainty Quantification Laboratory Directed Research and Development Project at LLNL under project tracking code 12-ERD-069.

  9. Wake Dynamics in the Atmospheric Boundary Layer Over Complex Terrain

    NASA Astrophysics Data System (ADS)

    Markfort, Corey D.

    The goal of this research is to advance our understanding of atmospheric boundary layer processes over heterogeneous landscapes and complex terrain. The atmospheric boundary layer (ABL) is a relatively thin (˜ 1 km) turbulent layer of air near the earth's surface, in which most human activities and engineered systems are concentrated. Its dynamics are crucially important for biosphere-atmosphere couplings and for global atmospheric dynamics, with significant implications on our ability to predict and mitigate adverse impacts of land use and climate change. In models of the ABL, land surface heterogeneity is typically represented, in the context of Monin-Obukhov similarity theory, as changes in aerodynamic roughness length and surface heat and moisture fluxes. However, many real landscapes are more complex, often leading to massive boundary layer separation and wake turbulence, for which standard models fail. Trees, building clusters, and steep topography produce extensive wake regions currently not accounted for in models of the ABL. Wind turbines and wind farms also generate wakes that combine in complex ways to modify the ABL. Wind farms are covering an increasingly significant area of the globe and the effects of large wind farms must be included in regional and global scale models. Research presented in this thesis demonstrates that wakes caused by landscape heterogeneity must be included in flux parameterizations for momentum, heat, and mass (water vapor and trace gases, e.g. CO2 and CH4) in ABL simulation and prediction models in order to accurately represent land-atmosphere interactions. Accurate representation of these processes is crucial for the predictions of weather, air quality, lake processes, and ecosystems response to climate change. Objectives of the research reported in this thesis are: 1) to investigate turbulent boundary layer adjustment, turbulent transport and scalar flux in wind farms of varying configurations and develop an improved

  10. Wind Tunnel Modeling Of Wind Flow Over Complex Terrain

    NASA Astrophysics Data System (ADS)

    Banks, D.; Cochran, B.

    2010-12-01

    This presentation will describe the finding of an atmospheric boundary layer (ABL) wind tunnel study conducted as part of the Bolund Experiment. This experiment was sponsored by Risø DTU (National Laboratory for Sustainable Energy, Technical University of Denmark) during the fall of 2009 to enable a blind comparison of various air flow models in an attempt to validate their performance in predicting airflow over complex terrain. Bohlund hill sits 12 m above the water level at the end of a narrow isthmus. The island features a steep escarpment on one side, over which the airflow can be expected to separate. The island was equipped with several anemometer towers, and the approach flow over the water was well characterized. This study was one of only two only physical model studies included in the blind model comparison, the other being a water plume study. The remainder were computational fluid dynamics (CFD) simulations, including both RANS and LES. Physical modeling of air flow over topographical features has been used since the middle of the 20th century, and the methods required are well understood and well documented. Several books have been written describing how to properly perform ABL wind tunnel studies, including ASCE manual of engineering practice 67. Boundary layer wind tunnel tests are the only modelling method deemed acceptable in ASCE 7-10, the most recent edition of the American Society of Civil Engineers standard that provides wind loads for buildings and other structures for buildings codes across the US. Since the 1970’s, most tall structures undergo testing in a boundary layer wind tunnel to accurately determine the wind induced loading. When compared to CFD, the US EPA considers a properly executed wind tunnel study to be equivalent to a CFD model with infinitesimal grid resolution and near infinite memory. One key reason for this widespread acceptance is that properly executed ABL wind tunnel studies will accurately simulate flow separation

  11. Complex terrain dispersion model plus algorithms for unstable situations (CTDMPLUS) (for microcomputers) (re-announcement). Model-Simulation

    SciTech Connect

    1990-12-31

    The Complex Terrain Dispersion Model Plus (CTDMPLUS) is a refined air quality model for use in all stability conditions for complex terrain applications. It contains the technology of the original Complex Terrain Dispersion Model (CTDM) for stable and neutral conditions, but also models daytime, unstable conditions. The model makes use of considerable detail in the terrain and meteorological data (as compared to current EPA regulatory models) and requires the parameterization of individual terrain features, thus considering the three-dimensional nature of the interaction of the plume and terrain.

  12. Stochastic Cascade Dynamical Downscaling of Precipitation over Complex Terrain

    NASA Astrophysics Data System (ADS)

    Posadas, A.; Duffaut, L. E.; Jones, C.; Carvalho, L. V.; Carbajal, M.; Heidinger, H.; Quiroz, R.

    2013-12-01

    spatial and temporal variability of rainfall between the rainfall fields obtained from the rain gauge network and those generated by the simulation model. The potential advantages of this methodology are discussed.Stochastic Cascade Dynamical Downscaling of Precipitation over Complex Terrain

  13. Consequence analysis for accidental releases of toxic substances in a complex terrain with shoreline in Korea

    SciTech Connect

    Ghim, Y.S.; Oh, H.S.; Moon, K.C.

    1999-07-01

    Offsite consequences resulting from various scenarios involving release of toxic substances in the Yochon Industrial Estate located in the Yosu Peninsula with complex terrain and intricate shorelines are estimated using ALOHA (Areal Locations of Hazardous Atmospheres) and RAMS (Regional Atmospheric Modeling System). ALOHA analyses by assuming the worst-case release scenarios for selected chemicals in the worst-case and alternative meteorological conditions indicate the impact on several thousand people in the nearby area. RAMS simulation is performed in order to consider the influence of terrain and shoreline. Receptors behind the terrain, 5 to 6 km distant from the source, also show high concentration when the wind blows to the terrain as well as receptors in front of the terrain in the nearby area. With considering the diurnal variations of meteorological variables, it is predicted that complicated wind patterns with low speeds could cause high concentration over the entire area adjacent to the Estate.

  14. Humans exploit the biomechanics of bipedal gait during visually guided walking over complex terrain.

    PubMed

    Matthis, Jonathan Samir; Fajen, Brett R

    2013-07-01

    How do humans achieve such remarkable energetic efficiency when walking over complex terrain such as a rocky trail? Recent research in biomechanics suggests that the efficiency of human walking over flat, obstacle-free terrain derives from the ability to exploit the physical dynamics of our bodies. In this study, we investigated whether this principle also applies to visually guided walking over complex terrain. We found that when humans can see the immediate foreground as little as two step lengths ahead, they are able to choose footholds that allow them to exploit their biomechanical structure as efficiently as they can with unlimited visual information. We conclude that when humans walk over complex terrain, they use visual information from two step lengths ahead to choose footholds that allow them to approximate the energetic efficiency of walking in flat, obstacle-free environments.

  15. Accurate Wind Characterization in Complex Terrain Using the Immersed Boundary Method

    SciTech Connect

    Lundquist, K A; Chow, F K; Lundquist, J K; Kosovic, B

    2009-09-30

    This paper describes an immersed boundary method (IBM) that facilitates the explicit resolution of complex terrain within the Weather Research and Forecasting (WRF) model. Two different interpolation methods, trilinear and inverse distance weighting, are used at the core of the IBM algorithm. Functional aspects of the algorithm's implementation and the accuracy of results are considered. Simulations of flow over a three-dimensional hill with shallow terrain slopes are preformed with both WRF's native terrain-following coordinate and with both IB methods. Comparisons of flow fields from the three simulations show excellent agreement, indicating that both IB methods produce accurate results. However, when ease of implementation is considered, inverse distance weighting is superior. Furthermore, inverse distance weighting is shown to be more adept at handling highly complex urban terrain, where the trilinear interpolation algorithm breaks down. This capability is demonstrated by using the inverse distance weighting core of the IBM to model atmospheric flow in downtown Oklahoma City.

  16. Comparison of four spatial interpolation methods for estimating soil moisture in a complex terrain catchment.

    PubMed

    Yao, Xueling; Fu, Bojie; Lü, Yihe; Sun, Feixiang; Wang, Shuai; Liu, Min

    2013-01-01

    Many spatial interpolation methods perform well for gentle terrains when producing spatially continuous surfaces based on ground point data. However, few interpolation methods perform satisfactorily for complex terrains. Our objective in the present study was to analyze the suitability of several popular interpolation methods for complex terrains and propose an optimal method. A data set of 153 soil water profiles (1 m) from the semiarid hilly gully Loess Plateau of China was used, generated under a wide range of land use types, vegetation types and topographic positions. Four spatial interpolation methods, including ordinary kriging, inverse distance weighting, linear regression and regression kriging were used for modeling, randomly partitioning the data set into 2/3 for model fit and 1/3 for independent testing. The performance of each method was assessed quantitatively in terms of mean-absolute-percentage-error, root-mean-square-error, and goodness-of-prediction statistic. The results showed that the prediction accuracy differed significantly between each method in complex terrain. The ordinary kriging and inverse distance weighted methods performed poorly due to the poor spatial autocorrelation of soil moisture at small catchment scale with complex terrain, where the environmental impact factors were discontinuous in space. The linear regression model was much more suitable to the complex terrain than the former two distance-based methods, but the predicted soil moisture changed too sharply near the boundary of the land use types and junction of the sunny (southern) and shady (northern) slopes, which was inconsistent with reality because soil moisture should change gradually in short distance due to its mobility in soil. The most optimal interpolation method in this study for the complex terrain was the hybrid regression kriging, which produced a detailed, reasonable prediction map with better accuracy and prediction effectiveness.

  17. Comparison of Four Spatial Interpolation Methods for Estimating Soil Moisture in a Complex Terrain Catchment

    PubMed Central

    Yao, Xueling; Fu, Bojie; Lü, Yihe; Sun, Feixiang; Wang, Shuai; Liu, Min

    2013-01-01

    Many spatial interpolation methods perform well for gentle terrains when producing spatially continuous surfaces based on ground point data. However, few interpolation methods perform satisfactorily for complex terrains. Our objective in the present study was to analyze the suitability of several popular interpolation methods for complex terrains and propose an optimal method. A data set of 153 soil water profiles (1 m) from the semiarid hilly gully Loess Plateau of China was used, generated under a wide range of land use types, vegetation types and topographic positions. Four spatial interpolation methods, including ordinary kriging, inverse distance weighting, linear regression and regression kriging were used for modeling, randomly partitioning the data set into 2/3 for model fit and 1/3 for independent testing. The performance of each method was assessed quantitatively in terms of mean-absolute-percentage-error, root-mean-square-error, and goodness-of-prediction statistic. The results showed that the prediction accuracy differed significantly between each method in complex terrain. The ordinary kriging and inverse distance weighted methods performed poorly due to the poor spatial autocorrelation of soil moisture at small catchment scale with complex terrain, where the environmental impact factors were discontinuous in space. The linear regression model was much more suitable to the complex terrain than the former two distance-based methods, but the predicted soil moisture changed too sharply near the boundary of the land use types and junction of the sunny (southern) and shady (northern) slopes, which was inconsistent with reality because soil moisture should change gradually in short distance due to its mobility in soil. The most optimal interpolation method in this study for the complex terrain was the hybrid regression kriging, which produced a detailed, reasonable prediction map with better accuracy and prediction effectiveness. PMID:23372749

  18. Mechanisms initiating deep convection over complex terrain during COPS.

    SciTech Connect

    Kottmeier, C.; Kalthoff, N.; Barthlott, C.; Corsmeier, U.; Van Baelen, J.; Coulter, R.; Environmental Science Division; Inst. for Meteorology and Climate Research; Lab. de Meteorologie Physique; Inst. of Physics and Meteorology

    2008-12-01

    Precipitating convection in a mountain region of moderate topography is investigated, with particular emphasis on its initiation in response to boundary-layer and mid- and upper-tropospheric forcing mechanisms. The data used in the study are from COPS (Convective and Orographically-induced Precipitation Study) that took place in southwestern Germany and eastern France in the summer of 2007. It is found that the initiation of precipitating convection can be roughly classified as being due to either: (i) surface heating and low-level flow convergence; (ii) surface heating and moisture supply overcoming convective inhibition during latent and/or potential instability; or (iii) mid-tropospheric dynamical processes due to mesoscale convergence lines and forced mean vertical motion. These phenomena have to be adequately represented in models in order to improve quantitative precipitation forecast. Selected COPS cases are analyzed and classified into these initiation categories. Although only a subset of COPS data (mainly radiosondes, surface weather stations, radar and satellite data) are used here, it is shown that convective systems are captured in considerable detail by sensor synergy. Convergence lines were observed by Doppler radar in the location where deep convection is triggered several hours later. The results suggest that in many situations, observations of the location and timing of convergence lines will facilitate the nowcasting of convection. Further on, forecasting of the initiation of convection is significantly complicated if advection of potentially convective air masses over changing terrain features plays a major role. The passage of a frontal structure over the Vosges - Rhine valley - Black Forest orography was accompanied by an intermediate suppression of convection over the wide Rhine valley. Further downstream, an intensification of convection was observed over the Black Forest due to differential surface heating, a convergence line, and the flow

  19. MELSAR: a mesoscale air quality model for complex terrain. Volume 2. Appendices

    SciTech Connect

    Allwine, K.J.; Whiteman, C.D.

    1985-04-01

    This final report is submitted as part of the Green River Ambient Model Assessment (GRAMA) project conducted at the US Department of Energy's Pacific Northwest Laboratory for the US Environmental Protection Agency. The GRAMA Program has, as its ultimate goal, the development of validated air quality models that can be applied to the complex terrain of the Green River Formation of western Colorado, eastern Utah and southern Wyoming. The Green River Formation is a geologic formation containing large reserves of oil shale, coal, and other natural resources. Development of these resources may lead to a degradation of the air quality of the region. Air quality models are needed immediately for planning and regulatory purposes to assess the magnitude of these regional impacts. This report documents one of the models being developed for this purpose within GRAMA - specifically a model to predict short averaging time (less than or equal to 24 h) pollutant concentrations resulting from the mesoscale transport of pollutant releases from multiple sources. MELSAR has not undergone any rigorous operational testing, sensitivity analyses, or validation studies. Testing and evaluation of the model are needed to gain a measure of confidence in the model's performance. This report consists of two volumes. This volume contains the Appendices, which include listings of the FORTRAN code and Volume 1 contains the model overview, technical description, and user's guide. 13 figs., 10 tabs.

  20. Downscaling surface wind predictions from numerical weather prediction models in complex terrain with WindNinja

    NASA Astrophysics Data System (ADS)

    Wagenbrenner, Natalie S.; Forthofer, Jason M.; Lamb, Brian K.; Shannon, Kyle S.; Butler, Bret W.

    2016-04-01

    Wind predictions in complex terrain are important for a number of applications. Dynamic downscaling of numerical weather prediction (NWP) model winds with a high-resolution wind model is one way to obtain a wind forecast that accounts for local terrain effects, such as wind speed-up over ridges, flow channeling in valleys, flow separation around terrain obstacles, and flows induced by local surface heating and cooling. In this paper we investigate the ability of a mass-consistent wind model for downscaling near-surface wind predictions from four NWP models in complex terrain. Model predictions are compared with surface observations from a tall, isolated mountain. Downscaling improved near-surface wind forecasts under high-wind (near-neutral atmospheric stability) conditions. Results were mixed during upslope and downslope (non-neutral atmospheric stability) flow periods, although wind direction predictions generally improved with downscaling. This work constitutes evaluation of a diagnostic wind model at unprecedented high spatial resolution in terrain with topographical ruggedness approaching that of typical landscapes in the western US susceptible to wildland fire.

  1. Complex Burial and Exhumation of South Polar Cap Pitted Terrain

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This image is illuminated by sunlight from the upper left. The two prominent bright stripes at the left/center of the image are covered with bright frost and thus create the illusion that they are sunlit from the lower left.

    The large pits, troughs, and 'swiss cheese' of the south polar residual cap appear to have been formed in the upper 4 or 5 layers of the polar material. Each layer is approximately 2 meters (6.6 feet) thick. Some Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) images of this terrain show examples in which older pitted and eroded layers have been previously buried and are now being exhumed. The example shown here includes two narrow, diagonal slopes that trend from upper left toward lower right at the left/center portion of the frame. Along the bottoms of these slopes are revealed a layer that underlies them in which there are many more pits and troughs than in the upper layer. It is likely in this case that the lower layer formed its pits and troughs before it was covered by the upper layer. This observation suggests that the troughs, pits, and 'swiss cheese' features of the south polar cap are very old and form over long time scales.

    The picture is located near 84.6oS, 45.1oW, and covers an area 3 km by 5 km (1.9 x 3.1 mi) at a resolution of about 3.8 meters (12 ft) per pixel. The image was taken during southern spring on August 29, 1999.

    Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

  2. Applications of digital image processing to ongoing research in complex terrain meteorology

    SciTech Connect

    Hubbe, J.M.; Whiteman, C.D.; Foote, H.P.; McWethy, L.G.

    1988-10-01

    Digital elevation models and Landsat 5 Thematic Mapper (TM) scenes constitute image resolution data over spatial domains of typical interest in complex terrain meteorology. Techniques in use and under development for applying these data to research problems are presented. Topics include decorrelation of topographic shading under direct beam illumination and investigation of nighttime surface temperature. 6 refs., 8 figs.

  3. Large Eddy Simulation of Stable Boundary Layer Turbulent Processes in Complex Terrain

    SciTech Connect

    Eric D. Skyllingstad

    2005-01-26

    Research was performed using a turbulence boundary layer model to study the behavior of cold, dense flows in regions of complex terrain. Results show that flows develop a balance between turbulent entrainment of warm ambient air and dense, cold air created by surface cooling. Flow depth and strength is a function of downslope distance, slope angle and angle changes, and the ambient air temperature.

  4. Numerical and Experimental Methods for Wake Flow Analysis in Complex Terrain

    NASA Astrophysics Data System (ADS)

    Castellani, Francesco; Astolfi, Davide; Piccioni, Emanuele; Terzi, Ludovico

    2015-06-01

    Assessment and interpretation of the quality of wind farms power output is a non-trivial task, which poses at least three main challenges: reliable comprehension of free wind flow, which is stretched to the limit on very complex terrains, realistic model of how wake interactions resemble on the wind flow, awareness of the consequences on turbine control systems, including alignment patterns to the wind and, consequently, power output. The present work deals with an onshore wind farm in southern Italy, which has been a test case of IEA- Task 31 Wakebench project: 17 turbines, with 2.3 MW of rated power each, are sited on a very complex terrain. A cluster of machines is investigated through numerical and experimental methods: CFD is employed for simulating wind fields and power extraction, as well as wakes, are estimated through the Actuator Disc model. SCADA data mining techniques are employed for comparison between models and actual performances. The simulations are performed both on the real terrain and on flat terrain, in order to disentangle the effects of complex flow and wake effects. Attention is devoted to comparison between actual alignment patterns of the cluster of turbines and predicted flow deviation.

  5. An Improved WRF for Urban-Scale and Complex-Terrain Applications

    SciTech Connect

    Lundquist, J K; Chow, F K; Mirocha, J D; Lundquist, K A

    2007-09-04

    Simulations of atmospheric flow through urban areas must account for a wide range of physical phenomena including both mesoscale and urban processes. Numerical weather prediction models, such as the Weather and Research Forecasting model (WRF), excel at predicting synoptic and mesoscale phenomena. With grid spacings of less than 1 km (as is required for complex heterogeneous urban areas), however, the limits of WRF's terrain capabilities and subfilter scale (SFS) turbulence parameterizations are exposed. Observations of turbulence in urban areas frequently illustrate a local imbalance of turbulent kinetic energy (TKE), which cannot be captured by current turbulence models. Furthermore, WRF's terrain-following coordinate system is inappropriate for high-resolution simulations that include buildings. To address these issues, we are implementing significant modifications to the ARW core of the Weather Research and Forecasting model. First, we are implementing an improved turbulence model, the Dynamic Reconstruction Model (DRM), following Chow et al. (2005). Second, we are modifying WRF's terrain-following coordinate system by implementing an immersed boundary method (IBM) approach to account for the effects of urban geometries and complex terrain. Companion papers detailing the improvements enabled by the DRM and the IBM approaches are also presented (by Mirocha et al., paper 13.1, and K.A. Lundquist et al., paper 11.1, respectively). This overview of the LLNL-UC Berkeley collaboration presents the motivation for this work and some highlights of our progress to date. After implementing both DRM and an IBM for buildings in WRF, we will be able to seamlessly integrate mesoscale synoptic boundary conditions with building-scale urban simulations using grid nesting and lateral boundary forcing. This multi-scale integration will enable high-resolution simulations of flow and dispersion in complex geometries such as urban areas, as well as new simulation capabilities in

  6. The role of the ASCOT program in dispersion studies in complex terrain

    SciTech Connect

    Doran, J.C.

    1994-12-31

    The US Department of Energy`s (DOE) Atmospheric Studies in Complex Terrain (ASCOT) program was established approximately 15 years ago to study the properties of the atmospheric boundary layer in areas of complex terrain, and to relate the knowledge gained through these studies to problems of transport and diffusion of atmospheric pollutants in such regions. While the program has evolved over the years to include phenomena over different scales, at various locations, and to address changing DOE mission needs, the concern with issues relevant to atmospheric dispersion has continued to be a major factor in the program`s research. This aspect of the program directly supports DOE`s interests in the areas of air quality and emergency preparedness. In this paper, some of ASCOT`s significant contributions to this field are reviewed.

  7. Photogrammetrically derived estimates of end-of-winter snow depth variability in complex terrain

    NASA Astrophysics Data System (ADS)

    Wolken, G. J.; Whorton, E.

    2015-12-01

    Seasonal snow is a key cryospheric variable because of its influence on energy and water budgets, public safety, and regional economies. Quantitative information on the spatial distribution of snow depth and snow water equivalence (SWE) is central to numerous applications in cryospheric research. However, in complex terrain, strong orographic gradients and wind redistribution produce complicated accumulation patterns that are difficult to capture using traditional in situ and satellite-based approaches, and are challenging to model with acceptable levels of uncertainty. Here we apply a repeat airborne photogrammetric approach and employ a Structure from Motion (SfM) processing method to generate digital surface models (DSMs) of snow-free and end-of-winter snow covered surfaces. Surface elevation differencing of these datasets produces a continuous and accurate snow depth map into which we assimilate in situ SWE measurements to produce detailed estimates of SWE over complex terrain in the maritime-continental transition zone of the eastern Chugach Mountains.

  8. The Collection of The Main Issues for Wind Farm Optimisation in Complex Terrain

    NASA Astrophysics Data System (ADS)

    Xu, Chang; Chen, Dandan; Han, Xingxing; Pan, Hangping; Shen, Wenzhong

    2016-09-01

    The paper aims at establishing the collection of the main issues for wind farm optimisation in complex terrain. To make wind farm cost effective, this paper briefly analyses the main factors influencing wind farm design in complex terrain and sets up a series of mathematical model that includes micro-siting, collector circuits, access roads design for optimization problems. The paper relies on the existing one year wind data in the wind farm area and uses genetic algorithm to optimize the micro-siting problem. After optimization of the turbine layout, single-source shortest path algorithm and minimum spanning tree algorithm are used to optimize collector circuits and access roads. The obtained results can provide important guidance for wind farms construction.

  9. Investigation of Microphysical Parameters within Winter and Summer Type Precipitation Events over Mountainous [Complex] Terrain

    SciTech Connect

    Stalker, James R.; Bossert, James E.

    1997-12-31

    In this study we investigate complex terrain effects on precipitation with RAMS for both in winter and summer cases from a microphysical perspective. We consider a two dimensional east-west topographic cross section in New Mexico representative of the Jemez mountains on the west and the Sangre de Cristo mountains on the east. Located between these two ranges is the Rio Grande Valley. In these two dimensional experiments, variations in DSDs are considered to simulate total precipitation that closely duplicate observed precipitation.

  10. Plume Dispersion Anomalies in a Nocturnal Urban Boundary Layer in Complex Terrain

    SciTech Connect

    Finn, Dennis D.; Clawson, Kirk L.; Carter, Roger G.; Rich, Jason D.; Allwine, K Jerry

    2008-11-01

    The URBAN 2000 experiments were conducted in the complex urban and topographical terrain in Salt Lake City in stable nighttime conditions. Unexpected plume dispersion often arose due to the interaction of complex terrain and mountain-valley flow dynamics, drainage flows, synoptic influences, and urban canopy affects, all within a nocturnal boundary layer. It was found that plume dispersion was strongly influenced by topography, that dispersion can be significantly different than what might be expected based upon the available wind data, and that it is problematic to rely on any one urban area wind measurement to predict or anticipate dispersion. Small-scale flows can be very important in dispersion and the potential effects of the larger scale, synoptically-driven flow field, and its interactions with the smaller scales, needs to be carefully considered. Some of the anomalies observed include extremely slow dispersion, complicated recirculation dispersion patterns in which plume transport was in directions opposed to the measured winds, and flow decoupling. Some of the plume dispersion anomalies could only be attributed to small-scale winds that were not resolved by the existing meteorological monitoring network. The results shown will make clear the difficulties in modeling or planning for emergency response to toxic releases in a nocturnal urban boundary layer within complex terrain.

  11. Improved quantitative precipitation estimation over complex terrain using cloud-to-ground lightning data

    NASA Astrophysics Data System (ADS)

    Minjarez-Sosa, Carlos Manuel

    Thunderstorms that occur in areas of complex terrain are a major severe weather hazard in the intermountain western U.S. Short-term quantitative estimation (QPE) of precipitation in complex terrain is a pressing need to better forecast flash flooding. Currently available techniques for QPE, that utilize a combination of rain gauge and weather radar information, may underestimate precipitation in areas where gauges do not exist or there is radar beam blockage. These are typically very mountainous and remote areas, that are quite vulnerable to flash flooding because of the steep topography. Lightning has been one of the novel ways suggested by the scientific community as an alternative to estimate precipitation over regions that experience convective precipitation, especially those continental areas with complex topography where the precipitation sensor measurements are scarce. This dissertation investigates the relationship between cloud-to-ground lightning and precipitation associated with convection with the purpose of estimating precipitation- mainly over areas of complex terrain which have precipitation sensor coverage problems (e.g. Southern Arizona). The results of this research are presented in two papers. The first, entitled Toward Development of Improved QPE in Complex Terrain Using Cloud-to-Ground Lighting Data: A case Study for the 2005 Monsoon in Southern Arizona, was published in the Journal of Hydrometeorology in December 2012. This initial study explores the relationship between cloud-to-ground lightning occurrences and multi-sensor gridded precipitation over southern Arizona. QPE is performed using a least squares approach for several time resolutions (seasonal---June, July and August---24 hourly and hourly) and for a 8 km grid size. The paper also presents problems that arise when the time resolution is increased, such as the spatial misplacing of discrete lightning events with gridded precipitation and the need to define a "diurnal day" that is

  12. The Nevada Rural Ozone Initiative (NVROI): Insights to understanding air pollution in complex terrain.

    PubMed

    Gustin, Mae Sexauer; Fine, Rebekka; Miller, Matthieu; Jaffe, Dan; Burley, Joel

    2015-10-15

    The Nevada Rural Ozone Initiative (NVROI) was established to better understand O3 concentrations in the Western United States (US). The major working hypothesis for development of the sampling network was that the sources of O3 to Nevada are regional and global. Within the framework of this overarching hypothesis, we specifically address two conceptual meteorological hypotheses: (1) The high elevation, complex terrain, and deep convective mixing that characterize Nevada, make this state ideally located to intercept polluted parcels of air transported into the US from the free troposphere; and (2) site specific terrain features will influence O3 concentrations observed at surface sites. Here, the impact of complex terrain and site location on observations are discussed. Data collected in Nevada at 6 sites (1385 to 2082 m above sea level (asl)) are compared with that collected at high elevation sites in Yosemite National Park and the White Mountains, California. Average daily maximum 1-hour concentrations of O3 during the first year of the NVROI ranged from 58 to 69 ppbv (spring), 53 to 62 ppbv (summer), 44 to 49 ppbv (fall), and 37 to 45 ppbv (winter). These were similar to those measured at 3 sites in Yosemite National Park (2022 to 3031 m asl), and at 4 sites in the White Mountains (1237 to 4342 m asl) (58 to 67 ppbv (summer) and 47 to 58 ppbv (fall)). Results show, that in complex terrain, collection of data should occur at high and low elevation sites to capture surface impacts, and site location with respect to topography should be considered. Additionally, concentrations measured are above the threshold reported for causing a reduction in growth and visible injury for plants (40 ppbv), and sustained exposure at high elevation locations in the Western USA may be detrimental for ecosystems.

  13. 9A.5 An Immersed Boundary Method for Flow Over Complex Terrain

    SciTech Connect

    Lundquist, K A; Chow, F K; Lundquist, J K

    2008-08-06

    Most mesoscale numerical models use terrain-following coordinates to accommodate complex terrain. Terrain-following or sigma coordinates conform to the bottom topography and the coordinate lines gradually become smoother and flatter with distance from the ground. With very steep terrain, the coordinate lines retain a signature of the underlying surface shape even very far away from the ground. Coordinate transformations are introduced into the discretized equations and produce numerical truncation errors in addition to those associated with the chosen discretization scheme. Several methods have been proposed to reduce the truncation error arising from terrain-following coordinates. Schar et al. [2002] proposed a modified sigma coordinate in which grid distortion due to small scale terrain features decays with height more rapidly than distortion caused by large scale features. The modified coordinate flattens quickly with height and improves the accuracy of the solution. Klemp et al. [2003] investigated the errors that arise when numerical treatment of the metric terms is inconsistent with the discretization of other terms in the governing equations. Distortion seen in topographically induced gravity waves was reduced with consistent numerical treatment. Adcroft et al. [1997] used a shaved cell approach to represent topography on a Cartesian grid. This method eliminates grid distortion, but introduces complications in the numerical solution at the ground because the computational cells must be modified (shaved) where they intersect the topography. Here we introduce an alternative griding technique for flow over complex terrain using an immersed boundary method (IBM) in the Weather Research and Forecasting (WRF) model. With this method, the terrain surface intersects the grid, and variables are adjusted near the immersed boundary so that the flow is diverted by the boundary. Grid distortion and the associated truncation errors are thus avoided. Additionally, the

  14. Comparison of Different Measurement Techniques and a CFD Simulation in Complex Terrain

    NASA Astrophysics Data System (ADS)

    Schulz, Christoph; Hofsäß, Martin; Anger, Jan; Rautenberg, Alexander; Lutz, Thorsten; Cheng, Po Wen; Bange, Jens

    2016-09-01

    This paper deals with a comparison of data collected by measurements and a simulation for a complex terrain test site in southern Germany. Lidar, met mast, unmanned aerial vehicle (UAV) measurements of wind speed and direction and Computational Fluid Dynamics (CFD) data are compared to each other. The site is characterised regarding its flow features and the suitability for a wind turbine test field. A Delayed-Detached-Eddy- Simulation (DES) was employed using measurement data to generate generic turbulent inflow. A good agreement of the wind profiles between the different approaches was reached. The terrain slope leads to a speed-up, a change of turbulence intensity as well as to flow angle variations.

  15. Enhancing radar estimates of precipitation over complex terrain using information derived from an orographic precipitation model

    NASA Astrophysics Data System (ADS)

    Crochet, Philippe

    2009-10-01

    SummaryThe objective of this paper is to present a radar-based quantitative precipitation estimation algorithm and assess its quality over the complex terrain of western Iceland. The proposed scheme deals with the treatment of beam blockage, anomalous propagation, vertical profile of reflectivity and includes a radar adjustment technique compensating for range, orographic effects and variations in the Z-R relationship. The quality of the estimated precipitation is remarkably enhanced after post-processing and in reasonably good agreement with what is known about the spatial distribution of precipitation in the studied area from both rain gauge observations and a gridded dataset derived from an orographic precipitation model. The results suggest that this methodology offers a credible solution to obtain an estimate of the distribution of precipitation in mountainous terrain and appears to be of practical value to meteorologists and hydrologists.

  16. Final Report of the Grant: ''Vertical Transport and Mixing in Complex Terrain Airsheds''

    SciTech Connect

    Fernando, Joseph Harindra; Anderson, James; Boyer, Don; Berman, Neil

    2004-12-29

    Stable stratification associated with nocturnal thermal circulation in areas of complex terrain leads to interesting and important phenomena that govern local meteorology and contaminant dispersion. Given that most urban areas are in complex topography, understanding and prediction of such phenomena are of immediate practical importance. This project dealt with theoretical, laboratory, numerical and field experimental studies aimed at understanding stratified flow and turbulence phenomena in urban areas, with particular emphasis on flow, turbulence and contaminant transport and diffusion in such flows. A myriad of new results were obtained and some of these results were used to improve the predictive capabilities of the models.

  17. Evaluation of Single-Doppler Radar Wind Retrievals in Flat and Complex Terrain

    SciTech Connect

    Newsom, Rob K.; Berg, Larry K.; Pekour, Mikhail S.; Fast, Jerome D.; Xu, Qin; Zhang, Pengfei; Yang, Qing; Shaw, William J.; Flaherty, Julia E.

    2014-08-01

    The accuracy of winds derived from NEXRAD level II data is assessed by comparison with independent observations from 915 MHz radar wind profilers. The evaluation is carried out at two locations with very different terrain characteristics. One site is located in an area of complex terrain within the State Line Wind Energy Center in northeast Oregon. The other site is located in an area of flat terrain on the east-central Florida coast. The National Severe Storm Laboratory’s 2DVar algorithm is used to retrieve wind fields from the KPDT (Pendleton OR) and KMLB (Melbourne FL) NEXRAD radars. Comparisons between the 2DVar retrievals and the radar profilers were conducted over a period of about 6 months and at multiple height levels at each of the profiler sites. Wind speed correlations at most observation height levels fell in the range from 0.7 to 0.8, indicating that the retrieved winds followed temporal fluctuations in the profiler-observed winds reasonably well. The retrieved winds, however, consistently exhibited slow biases in the range of1 to 2 ms-1. Wind speed difference distributions were broad with standard deviations in the range from 3 to 4 ms-1. Results from the Florida site showed little change in the wind speed correlations and difference standard deviations with altitude between about 300 and 1400 m AGL. Over this same height range, results from the Oregon site showed a monotonic increase in the wind speed correlation and a monotonic decrease in the wind speed difference standard deviation with increasing altitude. The poorest overall agreement occurred at the lowest observable level (~300 m AGL) at the Oregon site, where the effects of the complex terrain were greatest.

  18. Simulation of tracer dispersion from elevated and surface releases in complex terrain

    NASA Astrophysics Data System (ADS)

    Hernández, J. F.; Cremades, L.; Baldasano, J. M.

    A new version of an advanced mesoscale dispersion modeling system for simulating passive air pollutant dispersion in the real atmospheric planetary boundary layer (PBL), is presented. The system comprises a diagnostic mass-consistent meteorological model and a Lagrangian particle dispersion model (LADISMO). The former version of LADISMO, developed according to Zannetti (Air pollution modelling, 1990), was based on the Monte Carlo technique and included calculation of higher-order moments of vertical random forcing for convective conditions. Its ability to simulate complex flow dispersion has been stated in a previous paper (Hernández et al. 1995, Atmospheric Environment, 29A, 1331-1341). The new version follows Thomson's scheme (1984, Q. Jl Roy. Met. Soc.110, 1107-1120). It is also based on Langevin equation and follows the ideas given by Brusasca et al. (1992, Atmospheric Environment26A, 707-723) and Anfossi et al. (1992, Nuovo Cemento 15c, 139-158). The model is used to simulate the dispersion and predict the ground level concentration (g.l.c.) of a tracer (SF 6) released from both an elevated source ( case a) and a ground level source ( case b) in a highly complex mountainous terrain during neutral and synoptically dominated conditions ( case a) and light and apparently stable conditions ( case b). The last case is considered as being a specially difficult task to simulate. In fact, few works have reported situations with valley drainage flows in complex terrains and real stable atmospheric conditions with weak winds. The model assumes that nearly calm situations associated to strong stability and air stagnation, make the lowest layers of PBL poorly diffusive (Brusasca et al., 1992, Atmospheric Environment26A, 707-723). Model results are verified against experimental data from Guardo-90 tracer experiments, an intensive field campaign conducted in the Carrion river valley (Northern Spain) to study atmospheric diffusion within a steep walled valley in mountainous

  19. Simulation of radioactive plume gamma dose over a complex terrain using Lagrangian particle dispersion model.

    PubMed

    Rakesh, P T; Venkatesan, R; Hedde, Thierry; Roubin, Pierre; Baskaran, R; Venkatraman, B

    2015-07-01

    FLEXPART-WRF is a versatile model for the simulation of plume dispersion over a complex terrain in a mesoscale region. This study deals with its application to the dispersion of a hypothetical air borne gaseous radioactivity over a topographically complex nuclear site in southeastern France. A computational method for calculating plume gamma dose to the ground level receptor is introduced in FLEXPART using the point kernel method. Comparison with another similar dose computing code SPEEDI is carried out. In SPEEDI the dose is calculated for specific grid sizes, the lowest available being 250 m, whereas in FLEXPART it is grid independent. Spatial distribution of dose by both the models is analyzed. Due to the ability of FLEXPART to utilize the spatio-temporal variability of meteorological variables as input, particularly the height of the PBL, the simulated dose values were higher than SPEEDI estimates. The FLEXPART-WRF in combination with point kernel dose module gives a more realistic picture of plume gamma dose distribution in a complex terrain, a situation likely under accidental release of radioactivity in a mesoscale range. PMID:25863323

  20. Complex landslide terrain in the Kamienne Mountains, Middle Sudetes, SW Poland

    NASA Astrophysics Data System (ADS)

    Migoń, Piotr; Pánek, Tomáš; Malik, Ireneusz; Hrádecký, Jan; Owczarek, Piotr; Šilhán, Karel

    2010-12-01

    Dense forest hides a complex landslide terrain in the Kamienne Mountains, a part of the Sudetes range in Central Europe. Combined geomorphological, geophysical and dendrochronological research was carried out in three representative localities in order to decipher patterns of landslide evolution, to determine the extent of slope deformations, and to assess the contemporary activity of landslide terrain. Field mapping revealed the very complex nature of slope failures, both in space and time. Deep-seated sliding was the principal type of movement, and was followed by rock wall retreat by fall in the depletion zone and earthflows in the toe area. Electric resistivity survey proved useful in constraining geometry of landslide units and suggests an occurrence of underground voids in the Lesista landslide area. Dendrochronological research focused on tree-ring reduction, reaction wood, wound and scar analysis that helped to unravel the pattern of debris supply and movement subsequent to the main events, which includes free fall, talus creep, and sliding over snow cover. Today, landslide complexes are at different stages of evolution. Whereas in some places the activity has been largely completed, in others we have found the evidence for failure surfaces ready to accommodate movement. Hence, although some landslides may be relict, it is unjustified to extend this notion to all signs of hillslope instability in the area.

  1. Simulation of radioactive plume gamma dose over a complex terrain using Lagrangian particle dispersion model.

    PubMed

    Rakesh, P T; Venkatesan, R; Hedde, Thierry; Roubin, Pierre; Baskaran, R; Venkatraman, B

    2015-07-01

    FLEXPART-WRF is a versatile model for the simulation of plume dispersion over a complex terrain in a mesoscale region. This study deals with its application to the dispersion of a hypothetical air borne gaseous radioactivity over a topographically complex nuclear site in southeastern France. A computational method for calculating plume gamma dose to the ground level receptor is introduced in FLEXPART using the point kernel method. Comparison with another similar dose computing code SPEEDI is carried out. In SPEEDI the dose is calculated for specific grid sizes, the lowest available being 250 m, whereas in FLEXPART it is grid independent. Spatial distribution of dose by both the models is analyzed. Due to the ability of FLEXPART to utilize the spatio-temporal variability of meteorological variables as input, particularly the height of the PBL, the simulated dose values were higher than SPEEDI estimates. The FLEXPART-WRF in combination with point kernel dose module gives a more realistic picture of plume gamma dose distribution in a complex terrain, a situation likely under accidental release of radioactivity in a mesoscale range.

  2. Lidar Descriptions of Mixing-Layer Thickness Characteristics in a Complex Terrain/Coastal Environment.

    NASA Astrophysics Data System (ADS)

    McElroy, James L.; Smith, Ted B.

    1991-05-01

    Airborne lidar and supplementary measurements made during a major study of air chemistry in southern California (SCCCAMP 1985) provided a rare opportunity to examine atmospheric boundary-layer structure in a coastal area with complex terrain. This structure results from a combination of daytime heating or convection in the boundary layer (CBL), the intrusion of a marine layer into the inland areas, the thermal internal boundary layer (TIBL) formed within the marine onshore flow, inland growth of the TIBL, interactions of the CBL and the TIBL, and airflow interactions with terrain features.Measurements showed offshore mixing-layer thicknesses during SCCCAMP to be quite uniform spatially and day to day at 100-200 m. Movement of this layer onshore occurred readily with terrain that sloped gradually upward (e.g., to 300 m MSL at 50 km inland), but was effectively blocked by a 400-500 m high coastal ridge. In the higher terrain beyond the coastal ridge, aerosol layers aloft were often created as a result of deep convection and of a combination of onshore flow and heated, upslope airflow activity. Such aerosol layers can extend far offshore when embedded in reverse circulations aloft.The forward boundary of the marine layer was quite sharp, resembling a miniature cold front. Within the marine layer the onshore flow initiates a TIBL at the coastline, which increases in depth with distance inland due to roughness and convective influences. A coherent marine layer with imbedded TIBL was maintained for inland distances of 20-50 km, depending on terrain. Intense heating occurred inland prior to the arrival and undercutting by the marine front. The resulting, effective mixing layer increased in thickness from a few hundred meters to nearly two kilometers in a very short distance.Comparisons of a representative, physically based TIBL and convective mixing-layer models with observed data indicate that they generally do a credible job of estimating the depth of the marine layer

  3. Control and learning for intelligent mobility of unmanned ground vehicles in complex terrains

    NASA Astrophysics Data System (ADS)

    Trentini, M.; Beckman, B.; Digney, B.

    2005-05-01

    The Autonomous Intelligent Systems program at Defence R&D Canada-Suffield envisions autonomous systems contributing to decisive operations in the urban battle space. Creating effective intelligence for these systems demands advances in perception, world representation, navigation, and learning. In the land environment, these scientific areas have garnered much attention, while largely ignoring the problem of locomotion in complex terrain. This is a gap in robotics research, where sophisticated algorithms are needed to coordinate and control robotic locomotion in unknown, highly complex environments. Unlike traditional control problems, intuitive and systematic control tools for robotic locomotion do not readily exist thus limiting their practical application. This paper addresses the mobility problem for unmanned ground vehicles, defined here as the autonomous maneuverability of unmanned ground vehicles in unknown, highly complex environments. It discusses the progress and future direction of intelligent mobility research at Defence R&D Canada-Suffield and presents the research tools, topics and plans to address this critical research gap.

  4. Predictions of plume dispersion in complex terrain: Eulerian versus Lagrangian models

    NASA Astrophysics Data System (ADS)

    Nguyen, K. C.; Noonan, J. A.; Galbally, I. E.; Physick, W. L.

    Simulations of dispersion from an elevated point source in complex terrain and non-stationary flow are presented using the Lagrangian atmospheric dispersion model (LADM, Physick et al., 1992, Air Pollution Modeling and its Applications, Vol. IX, pp. 725-729, Plenum Press, New York; 1994 CSIRO Division of Atmospheric Research Technical Paper No. 24) and the Eulerian grid-based model (CALGRID, Yamartino et al., 1989, CALGRID: a mesoscale photochemical grid model, Vol. I; model formation document, Report, Sacarmento, California). Both models use the same predicted windfields. We find that • the different algorithms used for release of pollutants into the model domains lead to initial concentrations at the release height in LADM one-third higher than in CALGRID. • The CALGRID plume spreads laterally over a larger region than does the LADM plume due to the finite-difference approach of CALGRID. The pollutant mass in the extra volume occupied by the CALGRID plume is less than 10% of that released. • The essentials of morning fumigation are simulated more realistically under the Lagrangian approach. In LADM the elevated plume is mixed down to the ground rapidly, causing a sharp increase in ground-level concentrations (glc), whereas, in CALGRID glc increase more gradually over a few hours. • The use of hourly averaged windfields in CALGRID compared to 10 min windfields in LADM leads to a relative separation of the two modelled plumes of 5 km at a distance of roughly 6 km downwind from the sources at 1500 LST. Consequently in complex terrain and non-stationary conditions, the plumes are subjected to different three-dimensional wind regimes. For the particular terrain studied, roughly 3% of the pollutant mass emitted into CALGRID during the day is transported above 3000 m after 1700 LST whereas only 0.8% is transported above this height in LADM. • During the daytime the CALGRID simulation produces maximum glc which are about 40% smaller than those predicted by LADM.

  5. Adding Complex Terrain and Stable Atmospheric Condition Capability to the Simulator for On/Offshore Wind Farm Applications (SOWFA) (Presentation)

    SciTech Connect

    Churchfield, M. J.

    2013-06-01

    This presentation describes changes made to NREL's OpenFOAM-based wind plant aerodynamics solver so that it can compute the stably stratified atmospheric boundary layer and flow over terrain. Background about the flow solver, the Simulator for Off/Onshore Wind Farm Applications (SOWFA) is given, followed by details of the stable stratification/complex terrain modifications to SOWFA, along with some preliminary results calculations of a stable atmospheric boundary layer and flow over a simple set of hills.

  6. Evaluation of REMTECH PA-2 phased array SODAR performance in Complex Terrain using in-situ turbulence instruments

    SciTech Connect

    Murray, D.R.; Catizone, P.A.; Hoffnagle, G.F.

    1994-12-31

    The introduction of the Complex Terrain Dispersion Model Plus Algorithms for Unstable Situations (CTDMPLUS model) by the Environmental Protection Agency (EPA) has created a need for detailed vertical profiles of wind speed, direction and turbulence for regulatory modeling. Most EPA models use only a single level of wind data, assume wind direction within the boundary layer is uniform and extrapolate wind speed based on logarithmic profiles. CTDMPLUS offers a more realistic paradigm for transport and dispersion in the boundary layer by utilizing measured wind profiles if available. Profile data used by CTDMPLUS must include the layer in which the plume is dispersing. For tall stack, heated effluent plume, the profile must extend to heights of several hundred meters above stack top. Doppler SOund Detection And Ranging (SODAR) systems provide a cost effective method for collecting the profile data. While EPA has approved the use of mean wind speed and direction data from SODARs for regulatory modeling purposes, the use of turbulence data has not been unconditionally accepted. In order to use turbulence data from a SODAR, the user must obtain concurrence from the agency that the turbulence data are acceptable and may be required to demonstrate that the data are reliable. This paper presents the results of a SODAR data evaluation project.

  7. Evaluating the accuracy and representativeness of Airborne Doppler Wind Lidar winds in complex terrain

    NASA Astrophysics Data System (ADS)

    Godwin, K.; Emmitt, G. D.; Greco, S.; De Wekker, S.

    2013-12-01

    An Airborne Doppler Wind Lidar (ADWL) was flown during the MATERHORN experiment in October 2012. The ADWL was used to obtain profiles of u,v,w,σlos and aerosol structure between the surface and flight level (~2500m AGL). The lidar returns were processed to obtain a vertical resolution of 50m and a complete profile every 1.5km. The aircraft (Navy Twin Otter) was flown in a 'lawnmower' pattern near and over Granite Mountain located at the Dugway Proving Grounds, Utah. Combining multiple Lines of Sight (LOS) measurements to construct a vertical profile in complex terrain presents several challenges that must be met before using these data in numerical models. In addition to the wind profiles obtained with a nadir conical scan, we pointed the beam straight down to obtain a direct measure of the vertical velocity of the air. With a precision of < 10 cm/s, mountain waves, katabatic flows and other complex terrain induced flow features are resolved and provide validation of model resolved flow features. Examples of ADWL profile grids will be presented along with a discussion of the methodology(s) used to evaluate the accuracy and representativeness of the ADWL winds. We will also illustrate how we are making comparisons with numerical model wind fields (WRF) by using a forward operator with lidar LOS observations. Particular attention will be paid to interpreting the non-conventional ADWL's estimate(s) of turbulent kinetic energy.

  8. Performance of Precipitation Algorithms During IPHEx and Observations of Microphysical Characteristics in Complex Terrain

    NASA Astrophysics Data System (ADS)

    Erlingis, J. M.; Gourley, J. J.; Kirstetter, P.; Anagnostou, E. N.; Kalogiros, J. A.; Anagnostou, M.

    2015-12-01

    An Intensive Observation Period (IOP) for the Integrated Precipitation and Hydrology Experiment (IPHEx), part of NASA's Ground Validation campaign for the Global Precipitation Measurement Mission satellite took place from May-June 2014 in the Smoky Mountains of western North Carolina. The National Severe Storms Laboratory's mobile dual-pol X-band radar, NOXP, was deployed in the Pigeon River Basin during this time and employed various scanning strategies, including more than 1000 Range Height Indicator (RHI) scans in coordination with another radar and research aircraft. Rain gauges and disdrometers were also positioned within the basin to verify precipitation estimates and estimation of microphysical parameters. The performance of the SCOP-ME post-processing algorithm on NOXP data is compared with real-time and near real-time precipitation estimates with varying spatial resolutions and quality control measures (Stage IV gauge-corrected radar estimates, Multi-Radar/Multi-Sensor System Quantitative Precipitation Estimates, and CMORPH satellite estimates) to assess the utility of a gap-filling radar in complex terrain. Additionally, the RHI scans collected in this IOP provide a valuable opportunity to examine the evolution of microphysical characteristics of convective and stratiform precipitation as they impinge on terrain. To further the understanding of orographically enhanced precipitation, multiple storms for which RHI data are available are considered.

  9. Intercomparison of terrain-following coordinate transformation and immersed boundary methods in large-eddy simulation of wind fields over complex terrain

    NASA Astrophysics Data System (ADS)

    Fang, Jiannong; Porté-Agel, Fernando

    2016-09-01

    Accurate modeling of complex terrain, especially steep terrain, in the simulation of wind fields remains a challenge. It is well known that the terrain-following coordinate transformation method (TFCT) generally used in atmospheric flow simulations is restricted to non-steep terrain with slope angles less than 45 degrees. Due to the advantage of keeping the basic computational grids and numerical schemes unchanged, the immersed boundary method (IBM) has been widely implemented in various numerical codes to handle arbitrary domain geometry including steep terrain. However, IBM could introduce considerable implementation errors in wall modeling through various interpolations because an immersed boundary is generally not co-located with a grid line. In this paper, we perform an intercomparison of TFCT and IBM in large-eddy simulation of a turbulent wind field over a three-dimensional (3D) hill for the purpose of evaluating the implementation errors in IBM. The slopes of the three-dimensional hill are not steep and, therefore, TFCT can be applied. Since TFCT is free from interpolation-induced implementation errors in wall modeling, its results can serve as a reference for the evaluation so that the influence of errors from wall models themselves can be excluded. For TFCT, a new algorithm for solving the pressure Poisson equation in the transformed coordinate system is proposed and first validated for a laminar flow over periodic two-dimensional hills by comparing with a benchmark solution. For the turbulent flow over the 3D hill, the wind-tunnel measurements used for validation contain both vertical and horizontal profiles of mean velocities and variances, thus allowing an in-depth comparison of the numerical models. In this case, TFCT is expected to be preferable to IBM. This is confirmed by the presented results of comparison. It is shown that the implementation errors in IBM lead to large discrepancies between the results obtained by TFCT and IBM near the surface

  10. Determining mixing depths in complex terrain near a power plant with radar profiler reflectivities

    SciTech Connect

    Gaynor, J.E.

    1994-12-31

    Numerous analyses of 915-MHz wind profiler data are now appearing in the literature in such applications as air quality. Another set of data from these radars is just beginning to be exploited. Pioneering work used radar reflectivity to estimate daytime mixing depths by relating this reflectivity in the form of signal-to-noise ratios to radar C{sub n}{sup 2}. This, in turn, can be related to mixed layer turbulence. These results add a new dimension to the 915-MHz wind profiler products. We used these estimated mixing depths to determine the extent of mixing at several distributed wind profiler sites in the very complex terrain of the Project MOHAVE which occurred during 1992.

  11. Wind Power Forecasting techniques in complex terrain: ANN vs. ANN-CFD hybrid approach

    NASA Astrophysics Data System (ADS)

    Castellani, Francesco; Astolfi, Davide; Mana, Matteo; Burlando, Massimiliano; Meißner, Cathérine; Piccioni, Emanuele

    2016-09-01

    Due to technology developments, renewable energies are becoming competitive against fossil sources and the number of wind farms is growing, which have to be integrated into power grids. Therefore, accurate power forecast is needed and often operators are charged with penalties in case of imbalance. Yet, wind is a stochastic and very local phenomenon, and therefore hard to predict. It has a high variability in space and time and wind power forecast is challenging. Statistical methods, as Artificial Neural Networks (ANN), are often employed for power forecasting, but they have some shortcomings: they require data sets over several years and are not able to capture tails of wind power distributions. In this work a pure ANN power forecast is compared against a hybrid method, based on the combination of ANN and a physical method using computational fluid dynamics (CFD). The validation case is a wind farm sited in southern Italy in a very complex terrain, with a wide spread turbine layout.

  12. Advanced airborne Doppler Wind Lidar signal processing for observations in complex terrain

    NASA Astrophysics Data System (ADS)

    Emmitt, G. D.; Godwin, K.

    2014-10-01

    An airborne Doppler Wind Lidar has been used in several atmospheric boundary layer field experiments over the past decade. These experiments have taken place in California (Salinas Valley and the Monterey Peninsula), Arizona (Yuma Proving Grounds), and Utah (Dugway Proving Grounds). A primary objective of these field experiments was to compare model predicted winds in mountainous areas with wind observations obtained from the lidar measurements. To accomplish this, there is a basic challenge to determine when a comparison is valid in space and time. Here we have introduced the case for combining 12 pint step stare scans (conical) with near nadir stares to better represent the vertical air motions in complex terrain. We have also described a new scanning pattern that allows for LOS intersections for desired altitudes such as a ridge line or a valley floor.

  13. When can a high-resolution simulation over complex terrain be called LES?

    NASA Astrophysics Data System (ADS)

    Cuxart, Joan

    2015-12-01

    The ceaseless rise of computational power leads to a continuous increase of the resolution of the numerical models of the atmosphere. It is found today that operational models are run at horizontal resolutions near 1 km whereas research exercises for flows over complex terrain use resolutions at the hectometer scale. Horizontal resolutions of 100 m or finer have been used to perform Large-Eddy Simulations (LES) for some specific regimes like, e.g., the atmospheric boundary-layer in idealized configurations. However, to use the name "Large-Eddy Simulation" implies to be able to resolve at least the largest turbulent energetic eddies, which is almost impossible to reach with resolutions of the order of 100m for a real case, where many different processes occur linked to different scales, many of them even smaller than 100 m. Therefore, LES is an inappropriate denomination for these numerical exercises, that may simply be called High-Resolution Mesoscale Simulations.

  14. GIS based climate regionalisation in complex terrain for low mountain ranges

    NASA Astrophysics Data System (ADS)

    Häntzschel, J.; Goldberg, V.; Bernhofer, Ch.

    2003-04-01

    In low mountain range areas with complex topography climate elements show a high variability caused by manifold interactions between relief and landuse. The lack of continuous measurements demands concepts for the transfer of regional climatic information into smaller scales. Here model approaches for net raditation, temperature and precipitation in small scaled heterogeneous areas are combined with a Geographic information system (GIS). To parameterise these approaches model output of the vegetation-boundary layer model HIRVAC (HIgh Resolution Vegetation Atmosphere Coupler) is used. These modified approaches were transferred in a GIS (ARC VIEW) environment to consider topographic influences like terrain geometry and sky view factor as well as the influence of different land use (e.g., pasture and forest) especially on net radiation. Depending on the horizontal resolution of the digital elevation data a model of area related meteorological surface data without any interpolation methods and associated loss of precision is feasible. To illustrate the results the area of the "Tharandter Wald" near Dresden was selected. The results show that the combined influences of topography and land use on radiation balance lead to complex patterns in a terrain with well distinguished land surface types and a small-scale topography. The solar radiation on a clear Spring day is, e.g., over areas with extreme northward elevation 10 times lower than over comparable southward orientated areas. The spruce areas in the forest have up to 2 times higher daily sums of net radiation than the adjacent clearcuts. The model results are in adequate agreement with continuous measurements of the "Anchor Station Tharandter Wald" for the investigated period. The results can be applied for water budget modelling, forest management and for downscaling of satellite information.

  15. Parameter Measurement and Estimation at Variable Scales: Example of Soil Temperature in Complex Terrain

    NASA Astrophysics Data System (ADS)

    Seyfried, M. S.

    2015-12-01

    The issue of matching measurement scale to application scale is long standing and frequently revisited with advances in instrumentation and computing power. In the past we have emphasized the importance of understanding the dominant processes and amount and nature of parameter variability when addressing these issues. Landscape-scale distribution of carbon and carbon fluxes is a primary focus of the Reynolds Creek Critical Zone Observatory (RC CZO). Soil temperature (Ts) is a critical parameter of generally unknown variability. Estimates of Ts are often based on air temperature (Ta), but it is understood that other factors control Ts, especially in complex terrain, where solar radiation may be a major driver. Data were collected at the Reynolds Creek Experimental Watershed (RCEW), which is 240 km2 in extent and covers a 1000 m elevation range. We used spatially extensive Ts data to evaluate correlations with Ta (915 m elevation gradient) on aspect neutral sites with similar vegetative cover. Effects of complex terrain were evaluated using a combination of fixed point measurements, fiber optic distributed temperature sensing and periodic, spatially distributed point measurements. We found that Ts over the elevation gradient followed Ta closely. However, within small subwatersheds with uniform Ta, Ts may be extremely variable, with a standard deviation of 8° C. This was strongly related to topographically associated land surface units (LSU's) and highly seasonal. Within LSU variability was generally low while there were seasonally significant differences between LSU's. The mean annual soil temperature difference between LSU's was greater than that associated with the 915 m elevation gradient. The seasonality of Ts variability was not directly related to solar radiation effects but rather to variations in cover. Scaling Ts requires high resolution accounting of topography in this environment. Spatial patterns of soil carbon at the RCEW are consistent with this.

  16. Experimental and Numerical Modelling of Flow over Complex Terrain: The Bolund Hill

    NASA Astrophysics Data System (ADS)

    Conan, Boris; Chaudhari, Ashvinkumar; Aubrun, Sandrine; van Beeck, Jeroen; Hämäläinen, Jari; Hellsten, Antti

    2016-02-01

    In the wind-energy sector, wind-power forecasting, turbine siting, and turbine-design selection are all highly dependent on a precise evaluation of atmospheric wind conditions. On-site measurements provide reliable data; however, in complex terrain and at the scale of a wind farm, local measurements may be insufficient for a detailed site description. On highly variable terrain, numerical models are commonly used but still constitute a challenge regarding simulation and interpretation. We propose a joint state-of-the-art study of two approaches to modelling atmospheric flow over the Bolund hill: a wind-tunnel test and a large-eddy simulation (LES). The approach has the particularity of describing both methods in parallel in order to highlight their similarities and differences. The work provides a first detailed comparison between field measurements, wind-tunnel experiments and numerical simulations. The systematic and quantitative approach used for the comparison contributes to a better understanding of the strengths and weaknesses of each model and, therefore, to their enhancement. Despite fundamental modelling differences, both techniques result in only a 5 % difference in the mean wind speed and 15 % in the turbulent kinetic energy (TKE). The joint comparison makes it possible to identify the most difficult features to model: the near-ground flow and the wake of the hill. When compared to field data, both models reach 11 % error for the mean wind speed, which is close to the best performance reported in the literature. For the TKE, a great improvement is found using the LES model compared to previous studies (20 % error). Wind-tunnel results are in the low range of error when compared to experiments reported previously (40 % error). This comparison highlights the potential of such approaches and gives directions for the improvement of complex flow modelling.

  17. Payette River Basin Project: Improving Operational Forecasting in Complex Terrain through Chemistry

    NASA Astrophysics Data System (ADS)

    Blestrud, D.; Kunkel, M. L.; Parkinson, S.; Holbrook, V. P.; Benner, S. G.; Fisher, J.

    2015-12-01

    Idaho Power Company (IPC) is an investor owned hydroelectric based utility, serving customers throughout southern Idaho and eastern Oregon. The University of Arizona (UA) runs an operational 1.8-km resolution Weather and Research Forecast (WRF) model for IPC, which is incorporated into IPC near and real-time forecasts for hydro, solar and wind generation, load servicing and a large-scale wintertime cloud seeding operation to increase winter snowpack. Winter snowpack is critical to IPC, as hydropower provides ~50% of the company's generation needs. In efforts to improve IPC's near-term forecasts and operational guidance to its cloud seeding program, IPC is working extensively with UA and the National Center for Atmospheric Research (NCAR) to improve WRF performance in the complex terrain of central Idaho. As part of this project, NCAR has developed a WRF based cloud seeding module (WRF CS) to deliver high-resolution, tailored forecasts to provide accurate guidance for IPC's operations. Working with Boise State University (BSU), IPC is conducting a multiyear campaign to validate the WRF CS's ability to account for and disperse the cloud seeding agent (AgI) within the boundary layer. This improved understanding of how WRF handles the AgI dispersion and fate will improve the understanding and ultimately the performance of WRF to forecast other parameters. As part of this campaign, IPC has developed an extensive ground based monitoring network including a Remote Area Snow Sampling Device (RASSD) that provides spatially and temporally discrete snow samples during active cloud seeding periods. To quantify AgI dispersion in the complex terrain, BSU conducts trace element analysis using LA-ICP-MS on the RASSD sampled snow to provide measurements (at the 10-12 level) of incorporated AgI, measurements are compare directly with WRF CS's estimates of distributed AgI. Modeling and analysis results from previous year's research and plans for coming seasons will be presented.

  18. MELSAR: a mesoscale air quality model for complex terrain. Volume 1. Overview, technical description and user's guide

    SciTech Connect

    Allwine, K.J.; Whiteman, C.D.

    1985-04-01

    This final report is submitted as part of the Green River Ambient Model Assessment (GRAMA) program conducted at the US Department of Energy's Pacific Northwest Laboratory for the US Environmental Protection Agency. The GRAMA program has, as its ultimate goal, the development of validated air quality models that can be applied to the complex terrain of the Green River Formation of western Colorado, eastern Utah, and southern Wyoming. The Green River Formation is a geologic formation containing large reserves of oil shale, coal, and other natural resources. Development of these resources may lead to a degradation of the air quality of the region. Air quality models are needed immediately for planning and regulatory purposes to assess the magnitude of these regional impacts. This report documents one of the models being developed for this purpose within GRAMA - specifically a model to predict short averaging time (less than or equal to 24 h) pollutant concentrations resulting from the mesoscale transport of pollutant releases from multiple sources. MELSAR has not undergone any rigorous operational testing, sensitivity analyses, or validation studies. Testing and evaluation of the model are needed to gain a measure of confidence in the model's performance. This report consists of two volumes. Volume 1 contains the model overview, technical description, and user's guide, and Volume 2 contains the Appendices which include listings of the FORTRAN code. 51 refs., 31 figs., 35 tabs.

  19. Measurements of thermal updraft intensity over complex terrain using American white pelicans and a simple boundary-layer forecast model

    USGS Publications Warehouse

    Shannon, H.D.; Young, G.S.; Yates, M.; Fuller, Mark R.; Seegar, W.

    2003-01-01

    An examination of boundary-layer meteorological and avian aerodynamic theories suggests that soaring birds can be used to measure the magnitude of vertical air motions within the boundary layer. These theories are applied to obtain mixed-layer normalized thermal updraft intensity over both flat and complex terrain from the climb rates of soaring American white pelicans and from diagnostic boundary-layer model-produced estimates of the boundary-layer depth zi and the convective velocity scale w*. Comparison of the flatland data with the profiles of normalized updraft velocity obtained from previous studies reveals that the pelican-derived measurements of thermal updraft intensity are in close agreement with those obtained using traditional research aircraft and large eddy simulation (LES) in the height range of 0.2 to 0.8 zi. Given the success of this method, the profiles of thermal vertical velocity over the flatland and the nearby mountains are compared. This comparison shows that these profiles are statistically indistinguishable over this height range, indicating that the profile for thermal updraft intensity varies little over this sample of complex terrain. These observations support the findings of a recent LES study that explored the turbulent structure of the boundary layer using a range of terrain specifications. For terrain similar in scale to that encountered in this study, results of the LES suggest that the terrain caused less than an 11% variation in the standard deviation of vertical velocity.

  20. Preliminary results from the Los Alamos TA54 complex terrain Atmospheric Transport Study (ATS)

    SciTech Connect

    Vold, E.; Chan, M.; Sanders, L.

    1995-09-01

    The Los Alamos National Laboratory (LANL) Low-Level Radioactive Waste (LLRW) disposal site at TA54, Area G la located on a mesa top amidst a complex terrain of finger like mesas typically 30 motors or more In height above canyons of widths varying from 100 to 300 motors. Atmospheric dispersion from this site is of concern for routine operations and for potential Incidents during waste retrieval operations. Indian lands are located In the dominant downwind direction within 500 m from the site and provide further incentive to understand the potential and actual impacts of waste disposal operations. The permanent network of meteorological towers at LANL have been located primarily at mesa-top locations to coincide with most laboratory facilities and as such do not resolve the effects of channeling in the canyons and the influence this has on potential surface releases. An Atmospheric Transport Study (ATS) was initiated to better understand the wind flow fields and dispersion from the LANL Waste Storage and Disposal facilities at TA-54, Area G. As part of this effort, a series of six portable meteorological towers were sited in the vicinity of Area G, two at mesa top locations, one just east of the site where the mesas have dissipated to mild ridges, and three in the canyons adjacent to the disposal site mesa as indicated on the topographic representation of the local terrain. Since 1994, the towers have collected horizontal wind velocities, pressure, temperature, relative humidity and a radiation gamma reading every fifteen minutes. The data bass is being analyzed for trends and to provide a basis for comparison to computational modeling efforts to predict the flow fields.

  1. Atmospheric turbulence in complex terrain: Verifying numerical model results with observations by remote-sensing instruments

    NASA Astrophysics Data System (ADS)

    Chan, P. W.

    2009-03-01

    The Hong Kong International Airport (HKIA) is situated in an area of complex terrain. Turbulent flow due to terrain disruption could occur in the vicinity of HKIA when winds from east to southwest climb over Lantau Island, a mountainous island to the south of the airport. Low-level turbulence is an aviation hazard to the aircraft flying into and out of HKIA. It is closely monitored using remote-sensing instruments including Doppler LIght Detection And Ranging (LIDAR) systems and wind profilers in the airport area. Forecasting of low-level turbulence by numerical weather prediction models would be useful in the provision of timely turbulence warnings to the pilots. The feasibility of forecasting eddy dissipation rate (EDR), a measure of turbulence intensity adopted in the international civil aviation community, is studied in this paper using the Regional Atmospheric Modelling System (RAMS). Super-high resolution simulation (within the regime of large eddy simulation) is performed with a horizontal grid size down to 50 m for some typical cases of turbulent airflow at HKIA, such as spring-time easterly winds in a stable boundary layer and gale-force southeasterly winds associated with a typhoon. Sensitivity of the simulation results with respect to the choice of turbulent kinetic energy (TKE) parameterization scheme in RAMS is also examined. RAMS simulation with Deardorff (1980) TKE scheme is found to give the best result in comparison with actual EDR observations. It has the potential for real-time forecasting of low-level turbulence in short-term aviation applications (viz. for the next several hours).

  2. Immersed Boundary Methods for High-Resolution Simulation of Atmospheric Boundary-Layer Flow Over Complex Terrain

    SciTech Connect

    Lundquist, K A

    2010-05-12

    Mesoscale models, such as the Weather Research and Forecasting (WRF) model, are increasingly used for high resolution simulations, particularly in complex terrain, but errors associated with terrain-following coordinates degrade the accuracy of the solution. Use of an alternative Cartesian gridding technique, known as an immersed boundary method (IBM), alleviates coordinate transformation errors and eliminates restrictions on terrain slope which currently limit mesoscale models to slowly varying terrain. In this dissertation, an immersed boundary method is developed for use in numerical weather prediction. Use of the method facilitates explicit resolution of complex terrain, even urban terrain, in the WRF mesoscale model. First, the errors that arise in the WRF model when complex terrain is present are presented. This is accomplished using a scalar advection test case, and comparing the numerical solution to the analytical solution. Results are presented for different orders of advection schemes, grid resolutions and aspect ratios, as well as various degrees of terrain slope. For comparison, results from the same simulation are presented using the IBM. Both two-dimensional and three-dimensional immersed boundary methods are then described, along with details that are specific to the implementation of IBM in the WRF code. Our IBM is capable of imposing both Dirichlet and Neumann boundary conditions. Additionally, a method for coupling atmospheric physics parameterizations at the immersed boundary is presented, making IB methods much more functional in the context of numerical weather prediction models. The two-dimensional IB method is verified through comparisons of solutions for gentle terrain slopes when using IBM and terrain-following grids. The canonical case of flow over a Witch of Agnesi hill provides validation of the basic no-slip and zero gradient boundary conditions. Specified diurnal heating in a valley, producing anabatic winds, is used to validate the

  3. How does complex terrain influence responses of carbon and water cycle processes to climate variability and climate change?

    EPA Science Inventory

    We are pursuing the ambitious goal of understanding how complex terrain influences the responses of carbon and water cycle processes to climate variability and climate change. Our studies take place in H.J. Andrews Experimental Forest, an LTER (Long Term Ecological Research) site...

  4. A Comparison of Multisensor Precipitation Estimation Methods in Complex Terrain for Flash Flood Warning and Mitigation

    NASA Astrophysics Data System (ADS)

    Cifelli, R.; Chen, H.; Chandrasekar, C. V.; Willie, D.; Reynolds, D.; Campbell, C.; Zhang, Y.; Sukovich, E.

    2012-12-01

    Investigating the uncertainties and improving the accuracy of quantitative precipitation estimation (QPE) is a critical mission of the National Oceanic and Atmospheric Administration (NOAA). QPE is extremely challenging in regions of complex terrain like the western U.S. because of the sparse coverage of ground-based radar, complex orographic precipitation processes, and the effects of beam blockages (e.g., Westrick et al. 1999). In addition, the rain gauge density in complex terrain is often inadequate to capture spatial variability in the precipitation patterns. The NOAA Hydrometeorology Testbed (HMT) conducts research on precipitation and weather conditions that can lead to flooding, and fosters transition of scientific advances and new tools into forecasting operations (see hmt.noaa.gov). The HMT program consists of a series of demonstration projects in different geographical regions to enhance understanding of region specific processes related to precipitation, including QPE. There are a number of QPE systems that are widely used across NOAA for precipitation estimation (e.g., Cifelli et al. 2011; Chandrasekar et al. 2012). Two of these systems have been installed at the NOAA Earth System Research Laboratory: Multisensor Precipitation Estimator (MPE) and National Mosaic and Multi-sensor QPE (NMQ) developed by NWS and NSSL, respectively. Both provide gridded QPE products that include radar-only, gauge-only and gauge-radar-merged, etc; however, these systems often provide large differences in QPE (in terms of amounts and spatial patterns) due to differences in Z-R selection, vertical profile of reflectivity correction, and gauge interpolation procedures. Determining the appropriate QPE product and quantification of QPE uncertainty is critical for operational applications, including water management decisions and flood warnings. For example, hourly QPE is used to correct radar based rain rates used by the Flash Flood Monitoring and Prediction (FFMP) package in

  5. Soil Temperature Variability in Complex Terrain measured using Distributed a Fiber-Optic Distributed Temperature Sensing

    NASA Astrophysics Data System (ADS)

    Seyfried, M. S.; Link, T. E.

    2013-12-01

    Soil temperature (Ts) exerts critical environmental controls on hydrologic and biogeochemical processes. Rates of carbon cycling, mineral weathering, infiltration and snow melt are all influenced by Ts. Although broadly reflective of the climate, Ts is sensitive to local variations in cover (vegetative, litter, snow), topography (slope, aspect, position), and soil properties (texture, water content), resulting in a spatially and temporally complex distribution of Ts across the landscape. Understanding and quantifying the processes controlled by Ts requires an understanding of that distribution. Relatively few spatially distributed field Ts data exist, partly because traditional Ts data are point measurements. A relatively new technology, fiber optic distributed temperature system (FO-DTS), has the potential to provide such data but has not been rigorously evaluated in the context of remote, long term field research. We installed FO-DTS in a small experimental watershed in the Reynolds Creek Experimental Watershed (RCEW) in the Owyhee Mountains of SW Idaho. The watershed is characterized by complex terrain and a seasonal snow cover. Our objectives are to: (i) evaluate the applicability of fiber optic DTS to remote field environments and (ii) to describe the spatial and temporal variability of soil temperature in complex terrain influenced by a variable snow cover. We installed fiber optic cable at a depth of 10 cm in contrasting snow accumulation and topographic environments and monitored temperature along 750 m with DTS. We found that the DTS can provide accurate Ts data (+/- .4°C) that resolves Ts changes of about 0.03°C at a spatial scale of 1 m with occasional calibration under conditions with an ambient temperature range of 50°C. We note that there are site-specific limitations related cable installation and destruction by local fauna. The FO-DTS provide unique insight into the spatial and temporal variability of Ts in a landscape. We found strong seasonal

  6. CAMx simulations with different resolutions in flatland and complex terrain for Austria

    NASA Astrophysics Data System (ADS)

    Hirtl, Marcus; Krüger, Bernd C.

    2010-05-01

    The regional weather forecast model ALADIN-Austria of the Central Institute for Meteorology and Geodynamics (ZAMG) is used in combination with the chemical transport model CAMx (www.camx.com) to conduct forecasts of gaseous and particulate air pollutants over Austria. The forecasts "which are done in cooperation with the University of Natural Resources and Applied Life Sciences in Vienna (BOKU)" are supported by the regional governments since 2005. In the operational model version, the Air Quality model for Austria (AQA), uses the operational meteorological forecasts conducted with ALADIN which has a horizontal resolution of 9.7 km. Since 2008 the higher resolved ALARO is also available at the ZAMG. It has a horizontal resolution of 4.9 km and models the PBL with more vertical layers than ALADIN. ALARO also uses more complex algorithms to calculate precipitation, radiation and TKE. Another advantage of ALARO concerning the chemical modeling with CAMx is that additionally to the higher resolved meteorological forecasts it is possible to use finer emission inventories which are available for Austria. From 2006 to 2007 a SODAR-RASS of the ZAMG was operated in the north-eastern Austrian flat lands (Kittsee) which provides a comprehensive data set to compare vertical profiles of wind and temperature with the model predictions. Both models are used as meteorological driver for the chemical dispersion model CAMx. The results of predicted PM10 concentrations are compared to air quality measurements in Kittsee and also to observations in complex terrain for a selected episode.

  7. Multiscale Precipitation Processes Over Mountain Terrain - Landform and Vegetation Controls of Microphysics and Convection in Complex Terrain

    NASA Astrophysics Data System (ADS)

    Barros, A. P.; Wilson, A. M.; Sun, X.; Duan, Y.

    2015-12-01

    Recent precipitation observations in mountainous regions do not exhibit the classical orographic enhancement with elevation, especially where fog and multi-layer clouds are persistent. The role of landform in modulating moisture convergence patterns and constraining the thermodynamic environment that supports the development of complex vertical structures of clouds and precipitation is discussed first using observations and model results from the IPHEx (Integrated Precipitation and Hydrology Experiment) field campaign in the Southern Appalachian Mountains (SAM). Analysis of the complex spatial heterogeneity of precipitation microphysics in the SAM suggests that seeder-feeder interactions (SFI) among stratiform precipitation, low level clouds (LLC), and fog play a governing role on the diurnal and seasonal cycles of observed precipitation regimes. Further, in the absence of synoptic-scale forcing, results suggest that evapotranspiration makes a significant contribution to the moisture budget in the lower atmosphere, creating super-saturation conditions favorable to CCN activation, LLC formation, and light rainfall. To investigate the role of evapotranspiration on the diurnal cycle of mountain precipitation further, range-scale modeling studies were conducted in the Central Andes. Specifically, high resolution WRF simulations for realistic and quasi-idealized ET withdrawal case-studies show that evapotranspiration fluxes modulated by landform govern convective activity in the lower troposphere, including cloud formation and precipitation processes that account for daily precipitation amounts as high as 50-70% depending on synoptic conditions and season. These studies suggest multiscale vegetation controls of orographic precipitation processes via atmospheric instability on the one hand, and low level super-saturation and local microphysics on the other. A conceptual model of multiscale interactions among vegetation, landform and moist processes over complex

  8. Seasonal differences in SO2 ground-level impacts from a power plant plume on complex terrain.

    PubMed

    Palau, J L; Meliá, J; Segarra, D; Pérez-Landa, G; Santa-Cruz, F; Millán, M M

    2009-02-01

    The objective of this study is to describe the seasonal differences in SO2 ground-level fumigations from a power plant situated on very complex terrain in the Iberian Peninsula within the Western Mediterranean Basin (WMB). The study area extends more than 80 km around the power plant on very complex semi-arid terrain. Considering different plume-rise schemes, by experimentation and modelling this study attempts to characterise the seasonal differences in both the plume footprint 80 km around the power plant and the turbulent regime (diurnal or nocturnal) driving the main contribution to the accumulated plume footprints at different distances from the power plant within a complex terrain region. Two markedly different SO2 ground-level distributions around the power plant are presented for the typical summer and winter dispersive scenarios in the area. Simulations show that the SO2 footprint of a plume being advected more than 450 m above ground level in complex terrain is highly dependent on the prevailing meteorological conditions and on the mesoscale perturbations of the synoptic flows within the lower layers of the troposphere. The results obtained show how on complex terrain, despite seasonal meteorological differences and under stable dispersive conditions, the simulated mechanical turbulence leeward of the mountain ranges reproduces highly concentrated SO2 fumigations on the ground more than 50 km away from the power plant. Besides, under summer convective activity, plume fumigations have been successfully simulated less than 15 km from the power plant. In conclusion, this study shows how measurements from air quality networks together with information obtained from atmospheric transport and diffusion models are able to characterise different transport scenarios. This is a clear advantage for the end-users and decision-makers who manage and optimise the regional air quality networks.

  9. Imposing land-surface fluxes at an immersed boundary for improved simulations of atmospheric flow over complex terrain

    SciTech Connect

    Lundquist, K A; Chow, F K; Lundquist, J K; Mirocha, J D

    2008-06-05

    Boundary layer flows are greatly complicated by the presence of complex terrain which redirects mean flow and alters the structure of turbulence. Surface fluxes of heat and moisture provide additional forcing which induce secondary flows, or can dominate flow dynamics in cases with weak mean flows. Mesoscale models are increasingly being used for numerical simulations of boundary layer flows over complex terrain. These models typically use a terrain-following coordinate transformation, but these introduce numerical errors over steep terrain. An alternative is to use an immersed boundary method which alleviates errors associated with the coordinate transformation by allowing the terrain to be represented as a surface which arbitrarily passes through a Cartesian grid. This paper describes coupling atmospheric physics models to an immersed boundary method implemented in the Weather Research and Forecasting (WRF) model in previous work [Lundquist et al., 2007]. When the immersed boundary method is used, boundary conditions must be imposed on the immersed surface for velocity and scalar surface fluxes. Previous algorithms, such as those used by Tseng and Ferziger [2003] and Balaras [2004], impose no-slip boundary conditions on the velocity field at the immersed surface by adding a body force to the Navier-Stokes equations. Flux boundary conditions for the advection-diffusion equation have not been adequately addressed. A new algorithm is developed here which allows scalar surface fluxes to be imposed on the flow solution at an immersed boundary. With this extension of the immersed boundary method, land-surface models can be coupled to the immersed boundary to provide realistic surface forcing. Validation is provided in the context of idealized valley simulations with both specified and parameterized surface fluxes using the WRF code. Applicability to real terrain is illustrated with a fully coupled two-dimensional simulation of the Owens Valley in California.

  10. Estimating Catchment-Scale Snowpack Variability in Complex Forested Terrain, Valles Caldera National Preserve, NM

    NASA Astrophysics Data System (ADS)

    Harpold, A. A.; Brooks, P. D.; Biederman, J. A.; Swetnam, T.

    2011-12-01

    Difficulty estimating snowpack variability across complex forested terrain currently hinders the prediction of water resources in the semi-arid Southwestern U.S. Catchment-scale estimates of snowpack variability are necessary for addressing ecological, hydrological, and water resources issues, but are often interpolated from a small number of point-scale observations. In this study, we used LiDAR-derived distributed datasets to investigate how elevation, aspect, topography, and vegetation interact to control catchment-scale snowpack variability. The study area is the Redondo massif in the Valles Caldera National Preserve, NM, a resurgent dome that varies from 2500 to 3430 m and drains from all aspects. Mean LiDAR-derived snow depths from four catchments (2.2 to 3.4 km^2) draining different aspects of the Redondo massif varied by 30%, despite similar mean elevations and mixed conifer forest cover. To better quantify this variability in snow depths we performed a multiple linear regression (MLR) at a 7.3 by 7.3 km study area (5 x 106 snow depth measurements) comprising the four catchments. The MLR showed that elevation explained 45% of the variability in snow depths across the study area, aspect explained 18% (dominated by N-S aspect), and vegetation 2% (canopy density and height). This linear relationship was not transferable to the catchment-scale however, where additional MLR analyses showed the influence of aspect and elevation differed between the catchments. The strong influence of North-South aspect in most catchments indicated that the solar radiation is an important control on snow depth variability. To explore the role of solar radiation, a model was used to generate winter solar forcing index (SFI) values based on the local and remote topography. The SFI was able to explain a large amount of snow depth variability in areas with similar elevation and aspect. Finally, the SFI was modified to include the effects of shading from vegetation (in and out of

  11. Evaluation of flash-flood discharge forecasts in complex terrain using precipitation

    USGS Publications Warehouse

    Yates, D.; Warner, T.T.; Brandes, E.A.; Leavesley, G.H.; Sun, Jielun; Mueller, C.K.

    2001-01-01

    Operational prediction of flash floods produced by thunderstorm (convective) precipitation in mountainous areas requires accurate estimates or predictions of the precipitation distribution in space and time. The details of the spatial distribution are especially critical in complex terrain because the watersheds are generally small in size, and small position errors in the forecast or observed placement of the precipitation can distribute the rain over the wrong watershed. In addition to the need for good precipitation estimates and predictions, accurate flood prediction requires a surface-hydrologic model that is capable of predicting stream or river discharge based on the precipitation-rate input data. Different techniques for the estimation and prediction of convective precipitation will be applied to the Buffalo Creek, Colorado flash flood of July 1996, where over 75 mm of rain from a thunderstorm fell on the watershed in less than 1 h. The hydrologic impact of the precipitation was exacerbated by the fact that a significant fraction of the watershed experienced a wildfire approximately two months prior to the rain event. Precipitation estimates from the National Weather Service's operational Weather Surveillance Radar-Doppler 1988 and the National Center for Atmospheric Research S-band, research, dual-polarization radar, colocated to the east of Denver, are compared. In addition, very short range forecasts from a convection-resolving dynamic model, which is initialized variationally using the radar reflectivity and Doppler winds, are compared with forecasts from an automated-algorithmic forecast system that also employs the radar data. The radar estimates of rain rate, and the two forecasting systems that employ the radar data, have degraded accuracy by virtue of the fact that they are applied in complex terrain. Nevertheless, the radar data and forecasts from the dynamic model and the automated algorithm could be operationally useful for input to surface

  12. Spatial assessment of atmosphere-ecosystem exchanges via micrometeorological measurements and footprint modelling over complex terrain

    NASA Astrophysics Data System (ADS)

    Zhao, Peng; Lüers, Johannes; Foken, Thomas

    2010-05-01

    Anthropogenic impacts on natural and managed ecosystems have increased seriously during recent years. Ecosystem functions are modified as a result, which have an apparent influence on ecosystem services. TERRECO, a joint activity of the University of Bayreuth, Kangwon National University in Korea, and Korean Forest Research Institute, focuses the goal on building a bridge between ecosystem performance in mountainous terrain and derived ecosystem services that are critical for human well being. As a sub-program of TERRECO, our study is concentrated in Haean-Myun Catchment, an intensively used landscape within the Soyang Lake watershed including Soyang Lake Reservoir, and a sub-catchment of the Han River system which drains 26% of the land surface of South Korea. The aim of our study is to better understand the energy and matter exchange above farmlands (rice fields and/or dry crops) during the whole growing period including monsoon seasons in such a complex terrain as Haean Basin in Korea. To determine reliable evaporation and net ecosystem exchange (NEE), and to determine reliable information about near surface atmospheric stratification conditions, including convective events in Haean Basin, an eddy covariance complex (USA-1, LI-7500) will be installed above a typical farmland in Haean Basin to collect the 3D wind vector, water vapor and carbon dioxide concentration. It will be running at a sampling frequency of 20 Hz continuously, from late April to October in 2010. A post-processing software packages called TK2 will be used to obtain reliable sensible and latent heat and carbon dioxide fluxes with a high standard in data quality. Ongoing Footprint analysis will give an opportunity to track the spatial contribution of the surrounding land uses to the observed heat and CO2 fluxes helping to interpret the data. Useful data will be picked out to determine the variability of the stratification of the near surface boundary atmospheric layer to better understand the

  13. Understanding Learner Agency as a Complex Dynamic System

    ERIC Educational Resources Information Center

    Mercer, Sarah

    2011-01-01

    This paper attempts to contribute to a fuller understanding of the nature of language learner agency by considering it as a complex dynamic system. The purpose of the study was to explore detailed situated data to examine to what extent it is feasible to view learner agency through the lens of complexity theory. Data were generated through a…

  14. A physically-based hybrid framework to estimate daily-mean surface fluxes over complex terrain

    NASA Astrophysics Data System (ADS)

    Huang, Hsin-Yuan; Hall, Alex

    2016-06-01

    In this study we developed and examined a hybrid modeling approach integrating physically-based equations and statistical downscaling to estimate fine-scale daily-mean surface turbulent fluxes (i.e., sensible and latent heat fluxes) for a region of southern California that is extensively covered by varied vegetation types over a complex terrain. The selection of model predictors is guided by physical parameterizations of surface flux used in land surface models and analysis showing net shortwave radiation that is a major source of variability in the surface energy budget. Through a structure of multivariable regression processes with an application of near-surface wind estimates from a previous study, we successfully reproduce dynamically-downscaled 3 km resolution surface flux data. The overall error in our estimates is less than 20 % for both sensible and latent heat fluxes, while slightly larger errors are seen in high-altitude regions. The major sources of error in estimates include the limited information provided in coarse reanalysis data, the accuracy of near-surface wind estimates, and an ignorance of the nonlinear diurnal cycle of surface fluxes when using daily-mean data. However, with reasonable and acceptable errors, this hybrid modeling approach provides promising, fine-scale products of surface fluxes that are much more accurate than reanalysis data, without performing intensive dynamical simulations.

  15. Design of a WSN for the Sampling of Environmental Variability in Complex Terrain

    PubMed Central

    Martín-Tardío, Miguel A.; Felicísimo, Ángel M.

    2014-01-01

    In-situ environmental parameter measurements using sensor systems connected to a wireless network have become widespread, but the problem of monitoring large and mountainous areas by means of a wireless sensor network (WSN) is not well resolved. The main reasons for this are: (1) the environmental variability distribution is unknown in the field; (2) without this knowledge, a huge number of sensors would be necessary to ensure the complete coverage of the environmental variability and (3) WSN design requirements, for example, effective connectivity (intervisibility), limiting distances and controlled redundancy, are usually solved by trial and error. Using temperature as the target environmental variable, we propose: (1) a method to determine the homogeneous environmental classes to be sampled using the digital elevation model (DEM) and geometric simulations and (2) a procedure to determine an effective WSN design in complex terrain in terms of the number of sensors, redundancy, cost and spatial distribution. The proposed methodology, based on geographic information systems and binary integer programming can be easily adapted to a wide range of applications that need exhaustive and continuous environmental monitoring with high spatial resolution. The results show that the WSN design is perfectly suited to the topography and the technical specifications of the sensors, and provides a complete coverage of the environmental variability in terms of Sun exposure. However these results still need be validated in the field and the proposed procedure must be refined. PMID:25412218

  16. Dispersion of TSP and PM(10) emissions from quarries in complex terrain.

    PubMed

    Tartakovsky, Dmitry; Stern, Eli; Broday, David M

    2016-01-15

    This study evaluates AERMOD and CALPUFF dispersion calculations of particulate matter emissions from stone quarries in two mountainous regions against TSP and PM10 measurements, using both observational and WRF-modeled meteorological data. Due to different model parameterization, AERMOD dispersion predictions were in better agreement with the measured concentrations than those obtained by CALPUFF. As expected, the smaller the distance between the meteorological station, the source (quarry) and the receptors, the better the predictions of both AERMOD and CALPUFF. In contrast, using in-situ wind field obtained by runs of the WRF meteorological model for the complex terrain study area provided, in general, less accurate dispersion estimates than when using (even remote) meteorological observations. In particular, using the three-dimensional WRF-modeled wind field within CALPUFF did not provide any advantage over using the two-dimensional wind field, which is the common procedure of AERMOD and CALPUFF. Dry deposition was more significant for ambient concentration estimation in AERMOD than in CALPUFF.

  17. Turbulent transport and production/destruction of ozone in a boundary layer over complex terrain

    NASA Technical Reports Server (NTRS)

    Greenhut, Gary K.; Jochum, Anne M.; Neininger, Bruno

    1994-01-01

    The first Intensive Observation Period (IOP) of the Swiss air pollution experiment POLLUMET took place in 1990 in the Aare River Valley between Bern and Zurich. During the IOP, fast response measurements of meteorological variables and ozone concentration were made within the boundary layer aboard a motorglider. In addition, mean values of meteorological variables and the concentrations of ozone and other trace species were measured using other aircraft, pilot balloons, tethersondes, and ground stations. Turbulent flux profiles of latent and sensible heat and ozone are calculated from the fast response data. Terms in the ozone mean concentration budget (time rate of change of mean concentration, horizontal advection, and flux divergence) are calculated for stationary time periods both before and after the passage of a cold front. The source/sink term is calculated as a residual in the budget, and its sign and magnitude are related to the measured concentrations of reactive trace species within the boundary layer. Relationships between concentration ratios of trace species and ozone concentration are determined in order to understand the influence of complex terrain on the processes that produce and destroy ozone.

  18. Hydrologic Simulations in Complex Terrain Conditioned on Different Precipitation Inputs During IPHEx

    NASA Astrophysics Data System (ADS)

    Anagnostou, E. N.; Erlingis, J. M.; Vergara, H. J.; Gourley, J. J.

    2014-12-01

    An Intensive Observation Period for the Integrated Precipitation and Hydrology Experiment (IPHEx), part of NASA's Ground Validation campaign for the newly launched Global Precipitation Measurement Mission took place from May-June 2014 in the Smoky Mountains of western North Carolina. As part of the experiment, the National Severe Storms Laboratory's (NSSL) mobile dual-pol X-band radar, NOXP, was deployed in the Pigeon River Basin (PRB). The purpose of this study is to evaluate the performance of different post-processing algorithms of NOXP data with the suite of observation platforms within the IPHEx domain. In addition, the impact of standard precipitation datasets (Stage IV gauge-corrected radar estimates, Multi-Radar/Multi-Sensor System Quantitative Precipitation Estimates, Tropical Rainfall Measuring Mission (TRMM) 3B42V7 rainfall, CMORPH, WRF, etc.) on the performance of the CREST hydrologic model at small basin scales in complex terrain will be examined. Hydrologic simulations using a version of CREST with a priori parameters were conducted in the three small catchments within the PRB previously studied by Tao and Barros (2013): the Cataloochee Creek Basin, the East Fork Pigeon River Basin, and the West Fork Pigeon River Basin.

  19. Wind Regimes in Complex Terrain of the Great Valley of Eastern Tennessee

    SciTech Connect

    Birdwell, Kevin R.

    2011-05-01

    This research was designed to provide an understanding of physical wind mechanisms within the complex terrain of the Great Valley of Eastern Tennessee to assess the impacts of regional air flow with regard to synoptic and mesoscale weather changes, wind direction shifts, and air quality. Meteorological data from 2008 2009 were analyzed from 13 meteorological sites along with associated upper level data. Up to 15 ancillary sites were used for reference. Two-step complete linkage and K-means cluster analyses, synoptic weather studies, and ambient meteorological comparisons were performed to generate hourly wind classifications. These wind regimes revealed seasonal variations of underlying physical wind mechanisms (forced channeled, vertically coupled, pressure-driven, and thermally-driven winds). Synoptic and ambient meteorological analysis (mixing depth, pressure gradient, pressure gradient ratio, atmospheric and surface stability) suggested up to 93% accuracy for the clustered results. Probabilistic prediction schemes of wind flow and wind class change were developed through characterization of flow change data and wind class succession. Data analysis revealed that wind flow in the Great Valley was dominated by forced channeled winds (45 67%) and vertically coupled flow (22 38%). Down-valley pressure-driven and thermally-driven winds also played significant roles (0 17% and 2 20%, respectively), usually accompanied by convergent wind patterns (15 20%) and large wind direction shifts, especially in the Central/Upper Great Valley. The behavior of most wind regimes was associated with detectable pressure differences between the Lower and Upper Great Valley. Mixing depth and synoptic pressure gradients were significant contributors to wind pattern behavior. Up to 15 wind classes and 10 sub-classes were identified in the Central Great Valley with 67 joined classes for the Great Valley at-large. Two-thirds of Great Valley at-large flow was defined by 12 classes. Winds

  20. Regional-Scale Flows in Complex Terrain: AN Observational and Numerical Investigation

    NASA Astrophysics Data System (ADS)

    Bossert, James E.

    1990-01-01

    An observational program has been conducted to investigate thermally-driven flows in complex terrain on meso-beta to meso-alpha scales (100-500 km). Data were collected from exposed mountaintop locations, throughout the state of Colorado, over the summers of 1984-1988. These field experiments have been called the Rocky Mountain Peaks Experiments (ROMPEX). The observations have shown the development of a recurrent "regional-scale" circulation system across the Colorado mountain barrier, operating on a diurnal time scale. The basic structure of this flow system consists of a daytime flow toward the mountains along the Continental Divide, and nocturnal winds away from this high terrain. Long -term averages show this circulation system to be the dominant wind pattern at several high altitude stations, revealing its climatological significance. Numerical simulations have been performed with the Colorado State University Regional Atmospheric Modelling System (CSU-RAMS) to provide further insight into the physical mechanisms forcing the observed regional-scale circulation system. An idealized three-dimensional experiment demonstrated that the late afternoon evolution of a deep mountain-plains solenoid above the Front Range crest into a shallow, westward propagating density current, generates strong nocturnal outflow winds along the western slope, similar to those found in the ROMPEX observations. Sensitivity experiments show that the thermal gradient produced by differential heating of the topography across Colorado is the primary driving force in the density current evolution. Additional sensitivity experiments show that the simulated diurnal evolution of the regional-scale circulation system is a robust feature which can occur over a range of ambient flow, stratification, and soil moisture conditions. A case study simulation revealed that synoptic-scale forcing can enhance the evolving regional-scale circulations in preferential areas along the eastern slope of the

  1. The effects of synoptical weather pattern and complex terrain on the formation of aerosol events in the Greater Taipei area.

    PubMed

    Chuang, Ming-Tung; Chiang, Pen-Chi; Chan, Chang-Chuan; Wang, Chu-Fang; Chang, E-E; Lee, Chung-Te

    2008-07-25

    The aerosol in the Taipei basin is difficult to transport outward under specific weather patterns owing to complex terrain blocking. In this study, seven weather patterns are identified from synoptic weather maps for aerosol events, which occurred from March 2002 to February 2005. Among the identified weather patterns, High Pressure Peripheral Circulation (HPPC), Warm area Ahead of a cold Front (WAF), TYPhoon (TYP), Pacific High Pressure system stretching westerly (PHP), Weak High Pressure system (WHP), and Weak Southern Wind (WSW) are related to terrain blocking. The remaining pattern is High Pressure system Pushing (HPP). The classification of the pollution origin of the air masses shows that 15% of event days were contributed by long-range transport (LRT), 20% by local pollution (LP), and 65% by LRT/LP mix. Terrain blocking causes aerosol accumulation from high atmospheric stability and weak winds occurring under HPPC, TYP, and PHP weather patterns when the Taipei basin is situated on the lee side of the Snow Mountains Chain (SMC). Terrain blocking also occurs when the Taipei basin is situated on the upwind of SMC and Mt. Da-Twen under WAF and WSW patterns. To study the variation of aerosol properties under the mixed influence of terrain and pollution origin, we conducted a field observation simultaneously at the urban, suburban, and background sites in the Greater Taipei area from April 14 to 23, 2004. Terrain blocking plays an important role in aerosol accumulation in the stagnant environment when the Taipei basin is on the lee side of SMC. On the other hand, the PM(2.5) sulfate level is stable with a fraction of 30% in PM(2.5) during the observation period at the urban (25%-33%) and background (25%-41%) sites. It indicates that background PM(2.5) sulfate is high on the West Pacific in winter.

  2. Advancing Satellite-Based Flood Prediction in Complex Terrain Using High-Resolution Numerical Weather Prediction

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Anagnostou, E. N.; Nikolopoulos, E. I.; Bartsotas, N. S.

    2015-12-01

    Floods constitute one of the most significant and frequent natural hazard in mountainous regions. Satellite-based precipitation products offer in many cases the only available source of QPE. However, satellite-based QPE over complex terrain suffer from significant bias that limits their applicability for hydrologic modeling. In this work we investigate the potential of a new correction procedure, which involves the use of high-resolution numerical weather prediction (NWP) model simulations to adjust satellite QPE. Adjustment is based on the pdf matching of satellite and NWP (used as reference) precipitation distribution. The impact of correction procedure on simulating the hydrologic response is examined for 15 storm events that generated floods over the mountainous Upper Adige region of Northern Italy. Atmospheric simulations were performed at 1-km resolution from a state-of-the-art atmospheric model (RAMS/ICLAMS). The proposed error correction procedure was then applied on the widely used TRMM 3B42 satellite precipitation product and the evaluation of the correction was based on independent in situ precipitation measurements from a dense rain gauge network (1 gauge / 70 km2) available in the study area. Satellite QPE, before and after correction, are used to simulate flood response using ARFFS (Adige River Flood Forecasting System), a semi-distributed hydrologic model, which is used for operational flood forecasting in the region. Results showed that bias in satellite QPE before correction was significant and had a tremendous impact on the simulation of flood peak, however the correction procedure was able to reduce bias in QPE and therefore improve considerably the simulated flood hydrograph.

  3. Testing the PRISM Temperature Model in Complex Terrain: Implications for Mountain Ecohydrology

    NASA Astrophysics Data System (ADS)

    Strachan, S.; Daly, C.; Millar, C.

    2015-12-01

    Studies in mountainous terrain related to ecology and hydrology often use interpolated climate products because of a lack of local observations. One dataset frequently used to develop plot-to-watershed scale climatologies is the PRISM (Parameter-elevation Regression on Independent Slopes Model) temperature model. Benefits of this approach include geographically-weighted station observations and topographic positioning modifiers, which become important factors for predicting temperature in complex topography. Because of the paucity of long-term climate records in mountain environments, validation of PRISM algorithms across diverse regions remains challenging, with end users instead relying on atmospheric relationships derived in sometimes distant geographic settings. Recent developments of the PRISM model have increased temporal resolution capability from monthly to daily, which in turn has allowed a reasonable test of PRISM performance during a single season at distributed points across a large watershed. Presented are results from testing instrumental observations of daily max/min temperature on 16 sites in the Walker Basin, CA-NV, located on open woodland slopes ranging from 1967 to 3111 m in elevation. Individual site MAE varies from 1.34 to 4.22 C with better performance observed during summertime as opposed to winter. We observe a consistent bias in minimum temperatures for all seasons across all sites, with bias in maximum temperatures varying with season. Model error for minimum is associated strongly with elevation, whereas model error for maximum is associated with topographic radiative indices (solar exposure and heat loading). These results indicate that actual temperature conditions across open mountain woodland slopes are more heterogeneous than interpolated models (such as PRISM) indicate, which in turn impacts prediction/modeling of landscape processes such as ecological niches, bioclimatic refugia, and snow hydrology.

  4. Dynamical downscaling of the ERA-40 reanalysis in complex terrain in Norway

    NASA Astrophysics Data System (ADS)

    Heikkilä, Ulla; Kvamstø, Nils Gunnar; Sandvik, Anne

    2010-05-01

    The increase in resolution of numerical mesoscale models in the last few years has enhanced the level of detail of atmospheric parameters, such as precipitation. It is however not straightforward to evaluate if the higher resolution actually improves the representaton of these parameters. This is an especially interesting issue in complex terrain, such as the west coast of Norway where there is a strong orographic enhancement of the precipitation. A high-resolution model allowing for a more accurate representation of the orography can be expected to improve the modelled precipitation in comparison with GCM or reanalysis data. In this work dynamical downscaling of the ERA-40 reanalysis data down to 10 km resolution over Norway was performed. We used the WRF regional climate model (www.wrf-model.org). Results from a 30-year period ranging from 1961 to 1990 are presented and evaluated against daily mean observations of precipitation, 2-meter temperature and 10-meter wind speed from a number of surface stations. The WRF model is reproducing the probability density functions of the modelled and observed daily mean parameters reasonably well. We also investigate the frequency of wet days as well as the occurrence of extreme events which is of high importance for future climate studies. The downscaled WRF results show clear improvement from the ERA-40 reanalysis in precipitation. Especially the number and intensity of high precipitation events is much improved due to the higher model resolution and therefore a better representation of the mountains on the Norwegian west coast. On the other hand, temperature and wind are reasonably well represented in the ERA-40 reanalysis and not significant improvement was found in the downscaled data set. We will also present a model intercomparison of these parameters with some of the models used in the PRUDENCE project.

  5. Geolocation of man-made reservoirs across terrains of varying complexity using GIS

    NASA Astrophysics Data System (ADS)

    Mixon, David M.; Kinner, David A.; Stallard, Robert F.; Syvitski, James P. M.

    2008-10-01

    The Reservoir Sedimentation Survey Information System (RESIS) is one of the world's most comprehensive databases of reservoir sedimentation rates, comprising nearly 6000 surveys for 1819 reservoirs across the continental United States. Sediment surveys in the database date from 1904 to 1999, though more than 95% of surveys were entered prior to 1980, making RESIS largely a historical database. The use of this database for large-scale studies has been limited by the lack of precise coordinates for the reservoirs. Many of the reservoirs are relatively small structures and do not appear on current USGS topographic maps. Others have been renamed or have only approximate (i.e. township and range) coordinates. This paper presents a method scripted in ESRI's ARC Macro Language (AML) to locate the reservoirs on digital elevation models using information available in RESIS. The script also delineates the contributing watersheds and compiles several hydrologically important parameters for each reservoir. Evaluation of the method indicates that, for watersheds larger than 5 km 2, the correct outlet is identified over 80% of the time. The importance of identifying the watershed outlet correctly depends on the application. Our intent is to collect spatial data for watersheds across the continental United States and describe the land use, soils, and topography for each reservoir's watershed. Because of local landscape similarity in these properties, we show that choosing the incorrect watershed does not necessarily mean that the watershed characteristics will be misrepresented. We present a measure termed terrain complexity and examine its relationship to geolocation success rate and its influence on the similarity of nearby watersheds.

  6. Geolocation of man-made reservoirs across terrains of varying complexity using GIS

    USGS Publications Warehouse

    Mixon, D.M.; Kinner, D.A.; Stallard, R.F.; Syvitski, J.P.M.

    2008-01-01

    The Reservoir Sedimentation Survey Information System (RESIS) is one of the world's most comprehensive databases of reservoir sedimentation rates, comprising nearly 6000 surveys for 1819 reservoirs across the continental United States. Sediment surveys in the database date from 1904 to 1999, though more than 95% of surveys were entered prior to 1980, making RESIS largely a historical database. The use of this database for large-scale studies has been limited by the lack of precise coordinates for the reservoirs. Many of the reservoirs are relatively small structures and do not appear on current USGS topographic maps. Others have been renamed or have only approximate (i.e. township and range) coordinates. This paper presents a method scripted in ESRI's ARC Macro Language (AML) to locate the reservoirs on digital elevation models using information available in RESIS. The script also delineates the contributing watersheds and compiles several hydrologically important parameters for each reservoir. Evaluation of the method indicates that, for watersheds larger than 5 km2, the correct outlet is identified over 80% of the time. The importance of identifying the watershed outlet correctly depends on the application. Our intent is to collect spatial data for watersheds across the continental United States and describe the land use, soils, and topography for each reservoir's watershed. Because of local landscape similarity in these properties, we show that choosing the incorrect watershed does not necessarily mean that the watershed characteristics will be misrepresented. We present a measure termed terrain complexity and examine its relationship to geolocation success rate and its influence on the similarity of nearby watersheds. ?? 2008 Elsevier Ltd. All rights reserved.

  7. Parameter Estimation In Ensemble Data Assimilation To Characterize Model Errors In Surface-Layer Schemes Over Complex Terrain

    NASA Astrophysics Data System (ADS)

    Hacker, Joshua; Lee, Jared; Lei, Lili

    2014-05-01

    Numerical weather prediction (NWP) models have deficiencies in surface and boundary layer parameterizations, which may be particularly acute over complex terrain. Structural and physical model deficiencies are often poorly understood, and can be difficult to identify. Uncertain model parameters can lead to one class of model deficiencies when they are mis-specified. Augmenting the model state variables with parameters, data assimilation can be used to estimate the parameter distributions as long as the forecasts for observed variables is linearly dependent on the parameters. Reduced forecast (background) error shows that the parameter is accounting for some component of model error. Ensemble data assimilation has the favorable characteristic of providing ensemble-mean parameter estimates, eliminating some noise in the estimates when additional constraints on the error dynamics are unknown. This study focuses on coupling the Weather Research and Forecasting (WRF) NWP model with the Data Assimilation Research Testbed (DART) to estimate the Zilitinkevich parameter (CZIL). CZIL controls the thermal 'roughness length' for a given momentum roughness, thereby controlling heat and moisture fluxes through the surface layer by specifying the (unobservable) aerodynamic surface temperature. Month-long data assimilation experiments with 96 ensemble members, and grid spacing down to 3.3 km, provide a data set for interpreting parametric model errors in complex terrain. Experiments are during fall 2012 over the western U.S., and radiosonde, aircraft, satellite wind, surface, and mesonet observations are assimilated every 3 hours. One ensemble has a globally constant value of CZIL=0.1 (the WRF default value), while a second ensemble allows CZIL to vary over the range [0.01, 0.99], with distributions updated via the assimilation. Results show that the CZIL estimates do vary in time and space. Most often, forecasts are more skillful with the updated parameter values, compared to the

  8. Scalar Transport and Dispersion in Complex Terrain within a High Resolution Mass-Consistent Wind Modeling Framework

    NASA Astrophysics Data System (ADS)

    Wagenbrenner, N. S.; Edburg, S. L.; Lamb, B.; Forthofer, J.

    2012-12-01

    In areas of complex terrain, fine-scale changes in topography or vegetation substantially alter the flow field, and in turn, the transport and dispersion of air pollutants, pheromones, or other scalars. Thus, accurate modeling of scalar transport in complex topography requires accurate prediction of the flow field at a high spatial resolution. Mesoscale weather models typically operate on horizontal grids of 4 km or larger and are not capable of handling the effects of sub-grid complex terrain, such as wind speed-up over ridges, flow channeling in valleys, flow separation around terrain obstacles, and enhanced surface roughness from vegetation. In this paper we describe a scalar transport algorithm (advection and turbulent diffusion) used with WindNinja, a high-resolution mass-consistent wind model. WindNinja operates on a terrain-following coordinate system with a hexahedral cell mesh that grows in vertical size with height above the ground. A variational calculus approach is used in WindNinja that results in fast run times on the order of one minute for a 50 km x 50 km domain and 100 m horizontal resolution. The advection-diffusion algorithm uses a first order closure scheme for turbulent diffusion, where diffusivities are parameterized based on mixing length theory and modified as a function of atmospheric stability. We initialize WindNinja simulations with output from mesoscale weather forecasts using the Weather Research and Forecasting (WRF) model to capture the large-scale atmospheric flows and stability conditions. Model performance is evaluated against field data collected under a range of conditions at different locations including a multi-day continuous tracer gas dispersion experiment in an orchard located on rolling terrain in eastern Washington and a post-wildfire PM10 monitoring campaign in SE Idaho. The combination of fast run times, low computational demands, and explicit treatment of terrain and vegetation at a high spatial resolution are expected

  9. The influence of surface characteristics on lapse rates and temperature profiles in areas of complex terrain

    NASA Astrophysics Data System (ADS)

    Pepin, N. C.; Pike, G.; Fower, D.; Schaefer, M.

    2012-12-01

    Temperatures near the ground are often decoupled from free-air equivalents, particularly in areas of complex relief and at high latitudes where cold air drainage occurs particularly when radiation balances become negative. This means that it is hard to predict spatial patterns of surface temperature in such regions. In this study several years of intensive field measurements in complex terrain in northern Finland (Kevo) and Sweden (Abisko) allow detailed examination of the interaction between land surface characteristics (including cryosphere), vegetation, and local/micro-climate in mountain basins. Temperature and vapour pressure were measured every 30 minutes for 5 years (2007-2012) at 60 sites at Kevo and for a winter season (September-June) at 52 sites in Abisko, ranging over 300/600 metres of elevation respectively. In Finland lapse rates vary considerably both seasonally and diurnally, the relative importance of seasonal and diurnal forcing changing throughout the year. The results show intense (up to +80 °C/km) and persistent inversion events during the winter months (NDJ) which are broken up by mechanical effects since there is no diurnal cycle. In the transition from winter into spring (FMA) these inversions still occur but increasing radiation imposes a diurnal pattern on their formation and destruction. As snow cover peaks in spring the interaction between surface albedo, land cover and radiation serves to amplify the diurnal cycle in lapse rates. Daytime lapse rates peak in spring because of an increase in albedo with elevation as dark trees give way to reflective snow. At night inversions rapidly reform. Summer lapse rates are modified (usually weakened) by the presence of open water at low elevations. In Abisko similar processes are shown to be at work, although since the valley system is more open and at a larger spatial scale, the range of lapse rate variability is slightly less and the influence of surface characteristics more subdued. Taken

  10. An evaluation of WRF's ability to reproduce the surface wind over complex terrain based on typical circulation patterns

    NASA Astrophysics Data System (ADS)

    Jiménez, P. A.; Dudhia, J.; González-Rouco, J. F.; Montávez, J. P.; García-Bustamante, E.; Navarro, J.; Vilã-Guerau de Arellano, J.; Muñoz-Roldán, A.

    2013-07-01

    The performance of the Weather Research and Forecasting (WRF) model to reproduce the surface wind circulations over complex terrain is examined. The atmospheric evolution is simulated using two versions of the WRF model during an over 13 year period (1992 to 2005) over a complex terrain region located in the northeast of the Iberian Peninsula. A high horizontal resolution of 2km is used to provide an accurate representation of the terrain features. The multiyear evaluation focuses on the analysis of the accuracy displayed by the WRF simulations to reproduce the wind field of the six typical wind patterns (WPs) identified over the area in a previous observational work. Each pattern contains a high number of days which allows one to reach solid conclusions regarding the model performance. The accuracy of the simulations to reproduce the wind field under representative synoptic situations, or pressure patterns (PPs), of the Iberian Peninsula is also inspected in order to diagnose errors as a function of the large-scale situation. The evaluation is accomplished using daily averages in order to inspect the ability of WRF to reproduce the surface flow as a result of the interaction between the synoptic scale and the regional topography. Results indicate that model errors can originate from problems in the initial and lateral boundary conditions, misrepresentations at the synoptic scale, or the realism of the topographic features.

  11. Challenges for high-resolution simulations of atmospheric flow over complex terrain

    NASA Astrophysics Data System (ADS)

    Chow, F. K.; Bao, J.; Simon, J. S.; Wiersema, D. J.; Zhou, B.; Daniels, M.; Lundquist, K. A.

    2015-12-01

    A number of challenges arise as numerical simulations of the atmospheric boundary layer flow move to higher and higher resolution. One is in the representation of the topography: at higher resolutions, more terrain details can be represented, and therefore the maximum resolved slope of the terrain increases to the point where it cannot be accommodated by traditional terrain-following coordinates. An immersed boundary method has been implemented in a mesoscale model for that purpose, so that terrain slopes of any magnitude can be included, such as urban geometries or steep mountains. Another challenge as models move to higher resolution is in the choice of the turbulence closure model. At coarse, mesoscale resolutions (~ 10 km horizontal spacing), a Reynolds-averaged approach is used. At fine resolutions (less than about 100 m), large-eddy simulation closures can be used. The intermediate scales are called the gray zone, and significant problems occur when either LES or RANS closures are used. These challenges are evaluated in the context of multi-scale simulations using grid nesting for atmospheric boundary layer flow studies.

  12. Section Height Determination Methods of the Isotopographic Surface in a Complex Terrain Relief

    ERIC Educational Resources Information Center

    Syzdykova, Guldana D.; Kurmankozhaev, Azimhan K.

    2016-01-01

    A new method for determining the vertical interval of isotopographic surfaces on rugged terrain was developed. The method is based on the concept of determining the differentiated size of the vertical interval using spatial-statistical properties inherent in the modal characteristic, the degree of variability of apical heights and the chosen map…

  13. Modeling wind speed and snow accumulation gradients across complex terrain from typically collected meteorological data

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mountain winds exhibit strong gradients over short distances due to the influence of terrain. In winter, the acceleration of wind over wind-exposed slopes and its consequent deceleration over lee slopes strongly influences snow distribution. The heterogeneous snow distribution effects soil moistur...

  14. Cold air drainage and modeled nocturnal leaf water potential in complex forested terrain.

    PubMed

    Hubbart, Jason A; Kavanagh, Kathleen L; Pangle, Robert; Link, Tim; Schotzko, Alisa

    2007-04-01

    Spatial variation in microclimate caused by air temperature inversions plays an important role in determining the timing and rate of many physical and biophysical processes. Such phenomena are of particular interest in mountainous regions where complex physiographic terrain can greatly complicate these processes. Recent work has demonstrated that, in some plants, stomata do not close completely at night, resulting in nocturnal transpiration. The following work was undertaken to develop a better understanding of nocturnal cold air drainage and its subsequent impact on the reliability of predawn leaf water potential (Psi(pd)) as a surrogate for soil water potential (Psi(s)). Eight temperature data loggers were installed on a transect spanning a vertical distance of 155 m along a north facing slope in the Mica Creek Experimental Watershed (MCEW) in northern Idaho during July and August 2004. Results indicated strong nocturnal temperature inversions occurring from the low- to upper-mid-slope, typically spanning the lower 88 m of the vertical distance. Based on mean temperatures for both months, inversions resulted in lapse rates of 29.0, 27.0 and 25.0 degrees C km(-1) at 0000, 0400 and 2000 h, respectively. At this scale (i.e., < 1 km), the observed lapse rates resulted in highly variable nighttime vapor pressure deficits (D) over the length of the slope, with variable impacts on modeled disequilibrium between soil and leaf water potential. As a result of cold air drainage, modeled Psi(pd) became consistently more negative (up to -0.3 MPa) at higher elevations during the night based on mean temperatures. Nocturnal inversions on the lower- and mid-slopes resulted in leaf water potentials that were at least 30 and 50% more negative over the lower 88 m of the inversion layer, based on mean and maximum temperatures, respectively. However, on a cloudy night, with low D, the maximum decrease in Psi(pd) was -0.04 MPa. Our results indicate that, given persistent cold air

  15. Implications of small-scale flow features to modeling dispersion over complex terrain

    SciTech Connect

    Banta, R.M.; Olivier, L.D.

    1996-03-01

    Small-scale, topographically forced wind systems often have a strong influence on flow over complex terrain. These systems are very difficult to measure, because of their limited spatial and temporal extent. They can be important, however, in the atmospheric transport of hazardous materials. For example, a nocturnal exit jet - a narrow stream of cold air-which flowed from Eldorado Canyon at the interface between the Rocky Mountains and the Colorado plains near the Rocky Flats Plant (RFP), swept over RFP for about 3 h in the middle of the night of 4-5 February 1991. It extended in depth from a few tens of meters to approximately 800 m above the ground. Because the jet was so narrow (2 km wide), it was poorly sampled by the meteorological surface mesonet, but it did prove to have an effect on the dispersion of tracer material released from RFP, producing a secondary peak in measured concentration to the southeast of RFP. The existence and behavior of the jet was documented by Environmental Technology Laboratory`s Doppler lidar system, a scanning, active remote-sensing system that provides fine-resolution wind measurements. The lidar was deployed as a part of a wintertime study of flow and dispersion in the RFP vicinity during February 1993. The MATHEW-ADPIC atmospheric dispersion model was run using the case study data from this night. It consists of three major modules: an interpolation scheme; MATHEW, a diagnostic wind-flow algorithm that calculates a mass-consistent interpolated flow; and ADPIC, a diffusion algorithm. The model did an adequate job of representing the main lobe of the tracer transport, but the secondary lobe resulting from the Eldorado Canyon exit jet was absent from the model result. Because the jet was not adequately represented in the input data, it did not appear in the modeled wind field. Thus, the effects of the jet on the transport of tracer material were not properly simulated by the diagnostic model. 26 refs., 10 figs., 2 tabs.

  16. Modeling of extreme dust pollution in the complex terrain of the Dead Sea Valley

    NASA Astrophysics Data System (ADS)

    Kishcha, Pavel; Rieger, Daniel; Metzger, Jutta; Starobinets, Boris; Bangert, Max; Vogel, Heike; Schaettler, Ulrich; Corsmeier, Ulrich; Alpert, Pinhas; Vogel, Bernhard

    2016-04-01

    surface dust concentration was reached in the western part of the valley. Therefore, our study indicates the difficulties in using satellite-based AOD for initializing dust concentration within numerical forecast systems over a region with complex terrain. Numerical model experiments with different domains and dust sources (both local and remote ones) permitted us to quantify the contribution of various source regions to the pronounced maximum of dust AOD in the Dead Sea valley. Specifically, the model showed that 30% of the maximum dust AOD stems from local emissions and about 70% from more remote ones from the upwind side of the Judean Mountains.

  17. Comparison of the complex terrain algorithms incorporated into two commonly used local-scale air pollution dispersion models (ADMS and AERMOD) using a hybrid model.

    PubMed

    Carruthers, David J; Seaton, Martin D; McHugh, Christine A; Sheng, Xiangyu; Solazzo, Efisio; Vanvyve, Emilie

    2011-11-01

    ADMS and AERMOD are the two most widely used dispersion models for regulatory purposes. It is, therefore, important to understand the differences in the predictions of the models and the causes of these differences. The treatment by the models of flat terrain has been discussed previously; in this paper the focus is on their treatment of complex terrain. The paper includes a discussion of the impacts of complex terrain on airflow and dispersion and how these are treated in ADMS and AERMOD, followed by calculations for two distinct cases: (i) sources above a deep valley within a relatively flat plateau area (Clifty Creek power station, USA); (ii) sources in a valley in hilly terrain where the terrain rises well above the stack tops (Ribblesdale cement works, England). In both cases the model predictions are markedly different. At Clifty Creek, ADMS suggests that the terrain markedly increases maximum surface concentrations, whereas the AERMOD complex terrain module has little impact. At Ribblesdale, AERMOD predicts very large increases (a factor of 18) in the maximum hourly average surface concentrations due to plume impaction onto the neighboring hill; although plume impaction is predicted by ADMS, the increases in concentration are much less marked as the airflow model in ADMS predicts some lateral deviation of the streamlines around the hill.

  18. Modelling of a Zonda wind event in a complex terrain region using WRF

    NASA Astrophysics Data System (ADS)

    Fernandez, R. P.; Cremades, P. G.; Lakkis, G.; Allende, D. G.; Santos, R.; Puliafito, S. E.

    2012-04-01

    The air quality modeling in a regional scale requires the coupling to Numerical Weather Prediction (NWP) models, mainly when a high spatial and temporal resolution is required, such as in those cases related to large pollutants emissions episodes or extreme weather events. The Weather Research and Forecasting (WRF) is a last generation NWP model which computes temperature, pressure, humidity and wind fields in high spatial and temporal resolution. In order to perform simulations in complex terrain regions, WRF must be locally configured to obtain a proper representation of the physical processes, and an independent validation must be performed, both under common and extreme conditions. Once the local configuration is obtained, a full atmospheric chemistry modeling can be performed by means of WRF-Chem. In this work a mesoescale event of Zonda wind (similar to Foehn and Chinook winds) affecting the topographically complex mountainous region of Mendoza (Argentina) on February 15th, 2007 is represented using WRF. The model results are compared to the Argentine National Weather Service (SMN) observations at "El Plumerillo" station (WMO #87418), showing a good performance. A description of the local model configuration and most important physical parameterizations selected for the simulations is given, including the improvement of the default resolution of land use and land cover (LULC) fields. The high resolution modeling domain considered is centered at the city of Mendoza (32° 53' South, 68° 50' West), it extends 200 km N/S × 160 km E/W and includes a 3-nested domain downscaling of 36, 12 and 4 km resolution, respectively. The results for the Zonda wind episode show a very good performance of the model both in spatial and temporal scales. The temporal dew point variation (the physical variable that best describes the Zonda wind) shows a good agreement with the measured values, with a sharp decrease of 20 °C (from 16 °C to -4 °C) in 3 hours. A full 3-D regional

  19. Development of an Immersed Boundary Method to Resolve Complex Terrain in the Weather Research and Forecasting Model

    SciTech Connect

    Lunquist, K A; Chow, F K; Lundquist, J K; Mirocha, J D

    2007-09-04

    simulations, on the other hand, are performed by numerical weather prediction (NWP) codes, which cannot handle the geometry of the urban landscape, but do provide a more complete representation of atmospheric physics. NWP codes typically use structured grids with terrain-following vertical coordinates, include a full suite of atmospheric physics parameterizations, and allow for dynamic synoptic scale lateral forcing through grid nesting. Terrain following grids are unsuitable for urban terrain, as steep terrain gradients cause extreme distortion of the computational cells. In this work, we introduce and develop an immersed boundary method (IBM) to allow the favorable properties of a numerical weather prediction code to be combined with the ability to handle complex terrain. IBM uses a non-conforming structured grid, and allows solid boundaries to pass through the computational cells. As the terrain passes through the mesh in an arbitrary manner, the main goal of the IBM is to apply the boundary condition on the interior of the domain as accurately as possible. With the implementation of the IBM, numerical weather prediction codes can be used to explicitly resolve urban terrain. Heterogeneous urban domains using the IBM can be nested into larger mesoscale domains using a terrain-following coordinate. The larger mesoscale domain provides lateral boundary conditions to the urban domain with the correct forcing, allowing seamless integration between mesoscale and urban scale models. Further discussion of the scope of this project is given by Lundquist et al. [2007]. The current paper describes the implementation of an IBM into the Weather Research and Forecasting (WRF) model, which is an open source numerical weather prediction code. The WRF model solves the non-hydrostatic compressible Navier-Stokes equations, and employs an isobaric terrain-following vertical coordinate. Many types of IB methods have been developed by researchers; a comprehensive review can be found in Mittal

  20. Analysis of the inversion monitoring capabilities of a monostatic acoustic radar in complex terrain. [Tennessee River Valley

    NASA Technical Reports Server (NTRS)

    Koepf, D.; Frost, W.

    1981-01-01

    A qualitative interpretation of the records from a monostatic acoustic radar is presented. This is achieved with the aid of airplane, helicopter, and rawinsonde temperature soundings. The diurnal structure of a mountain valley circulation pattern is studied with the use of two acoustic radars, one located in the valley and one on the downwind ridge. The monostatic acoustic radar was found to be sufficiently accurate in locating the heights of the inversions and the mixed layer depth to warrant use by industry even in complex terrain.

  1. N cycle and retention of croplands in complex terrain, South Korea

    NASA Astrophysics Data System (ADS)

    Kettering, J.; Arnhold, S.; Kuzyakov, Y.; Lee, B.; Lindner, S.; Ok, Y.; Ruidisch, M.; Tenhunen, J. D.

    2009-12-01

    The aims of our research are to gain a deeper understanding of processes and interactions in agricultural ecosystems as well as to make a contribution to sustainable agricultural production in changing environments. While crop production is highly desirable, negative effects include high input of nutrients, greater erosion rates, removal of nutrients and carbon in harvests, and decreases in the quality of soil organic matter. The field sites of this project are located in Haean basin in the central part of Korea, just south of the demilitarized zone. Intensive land use with high levels of fertilization together with distinctive erosion during the summer monsoon can be found on site. One part of this study focuses on general fertilizer budgets at catchment scale as well as on detailed information about the dynamics and pathways of nitrogen in soil-plant systems on upland slopes. These balances of elements and their fluxes are the main background information in soil-plant studies. The integrative approach of a general budget is based on a large spatial allocation of the field sites, different management types (conventional, organic), and on several typical crops of the Haean basin. In this project, various perspectives are combined (i.e. insects, weed, crops, nutrients). This allows representative conclusions for the entire catchment as well as for the modeling. The approach of a detailed N cycle uses an integrated experimental strategy within run-off plots. Charred biomass and synthetic polymers were additionally applied in these run-off plots to determine whether these additives can contribute significantly to sustainable farming methods in such complex terrain. Within this integrative approach, each treatment was tested for erosion prevention, soil hydrological parameters and flow systems, nutrient balances, as well as plant growth and yields. Finally, best agricultural management practices for sustainable land use of sloping uplands will be suggested. The methods

  2. The influence of topographic co-variables on the spatial variability of precipitation over small regions of complex terrain

    NASA Astrophysics Data System (ADS)

    Diodato, Nazzareno

    2005-03-01

    Precipitation variability results from atmospheric circulation and complex site-specific bio-geoclimatic characteristics; therefore, climatic variables are expected to be correlated in a scale-dependent way. This paper studies the influence of topographic co-variables on the spatial variability of precipitation over small regions of complex terrain. For this purpose, the mutual benefits of an integrated geographic information system (GIS) and a geostatistics approach was used for spatial precipitation interpolation from rainfall observations measured at 51 climatic stations in a mountainous region of southern Italy (Benevento province). As no single method is optimal for all regions, it is important to compare the results obtained using alternative methods applied to the same data set. Therefore, besides ordinary kriging examination, two auxiliary variables were added for ordinary co-kriging of annual and seasonal precipitation: terrain elevation data and a topographic index. Cross-validation indicated that the ordinary kriging yielded the largest prediction errors. The smallest prediction errors were produced by a multivariate geostatistical method. However, the results favour the ordinary co-kriging with inclusion of information on the topographic index. The application of co-kriging is particularly justified in areas where there are nearby stations and where landform is very complex. We conclude that ordinary co-kriging is a very flexible and robust interpolation method because it may take into account several properties (soft and hard data) of the landscape.

  3. Adding Complex Terrain and Stable Atmospheric Condition Capability to the OpenFOAM-based Flow Solver of the Simulator for On/Offshore Wind Farm Applications (SOWFA): Preprint

    SciTech Connect

    Churchfield, M. J.; Sang, L.; Moriarty, P. J.

    2013-09-01

    This paper describes changes made to NREL's OpenFOAM-based wind plant aerodynamics solver such that it can compute the stably stratified atmospheric boundary layer and flow over terrain. Background about the flow solver, the Simulator for Off/Onshore Wind Farm Applications (SOWFA) is given, followed by details of the stable stratification/complex terrain modifications to SOWFA, along with somepreliminary results calculations of a stable atmospheric boundary layer and flow over a simply set of hills.

  4. Complex terrain alters temperature and moisture limitations of forest soil respiration across a semiarid to subalpine gradient

    USGS Publications Warehouse

    Berryman, Erin Michele; Barnard, H.R.; Adams, H.R.; Burns, M.A.; Gallo, E.; Brooks, P.D.

    2015-01-01

    Forest soil respiration is a major carbon (C) flux that is characterized by significant variability in space and time. We quantified growing season soil respiration during both a drought year and a nondrought year across a complex landscape to identify how landscape and climate interact to control soil respiration. We asked the following questions: (1) How does soil respiration vary across the catchments due to terrain-induced variability in moisture availability and temperature? (2) Does the relative importance of moisture versus temperature limitation of respiration vary across space and time? And (3) what terrain elements are important for dictating the pattern of soil respiration and its controls? Moisture superseded temperature in explaining watershed respiration patterns, with wetter yet cooler areas higher up and on north facing slopes yielding greater soil respiration than lower and south facing areas. Wetter subalpine forests had reduced moisture limitation in favor of greater seasonal temperature limitation, and the reverse was true for low-elevation semiarid forests. Coincident climate poorly predicted soil respiration in the montane transition zone; however, antecedent precipitation from the prior 10 days provided additional explanatory power. A seasonal trend in respiration remained after accounting for microclimate effects, suggesting that local climate alone may not adequately predict seasonal variability in soil respiration in montane forests. Soil respiration climate controls were more strongly related to topography during the drought year highlighting the importance of landscape complexity in ecosystem response to drought.

  5. Estimation of spatially distributed latent energy flux over complex terrain using a scanning water-vapor Raman lidar

    SciTech Connect

    Cooper, D.I.; Eichinger, W.; Archuleta, J.; Cottingame, W.; Osborne, M.; Tellier, L.

    1995-09-01

    Evapotranspiration is one of the critical variables in both water and energy balance models of the hydrological system. The hydrologic system is driven by the soil-plant-atmosphere continuum, and as such is a spatially distributed process. Traditional techniques rely on point sensors to collect information that is then averaged over a region. The assumptions involved in spatially average point data is of limited value (1) because of limited sensors in the arrays, (2) the inability to extend and interpret the Measured scalars and estimated fluxes at a point over large areas in complex terrain, and (3) the limited understanding of the relationship between point measurements of spatial processes. Remote sensing technology offers the ability to collect detailed spatially distributed data. However, the Los Alamos National Laboratory`s volume-imaging, scanning water-vapor Raman lidar has been shown to be able to estimate the latent energy flux at a point. The extension of this capability to larger scales over complex terrain represents a step forward. This abstract Outlines the techniques used to estimate the spatially resolved latent energy flux. The following sections describe the site, model, data acquired, and lidar estimated latent energy ``map``.

  6. Structure, Agency, Complexity Theory and Interdisciplinary Research in Education Studies

    ERIC Educational Resources Information Center

    Smith, John A.

    2013-01-01

    This article argues that Education Studies needs to develop its existing interdisciplinarity understanding of structures and agencies by giving greater attention to the modern process theories of self-organisation in the physical, biological, psychological and social sciences, sometimes given the umbrella term "complexity theory". The…

  7. Airborne Lidar-Based Estimates of Tropical Forest Structure in Complex Terrain: Opportunities and Trade-Offs for REDD+

    NASA Technical Reports Server (NTRS)

    Leitold, Veronika; Keller, Michael; Morton, Douglas C.; Cook, Bruce D.; Shimabukuro, Yosio E.

    2015-01-01

    Background: Carbon stocks and fluxes in tropical forests remain large sources of uncertainty in the global carbon budget. Airborne lidar remote sensing is a powerful tool for estimating aboveground biomass, provided that lidar measurements penetrate dense forest vegetation to generate accurate estimates of surface topography and canopy heights. Tropical forest areas with complex topography present a challenge for lidar remote sensing. Results: We compared digital terrain models (DTM) derived from airborne lidar data from a mountainous region of the Atlantic Forest in Brazil to 35 ground control points measured with survey grade GNSS receivers. The terrain model generated from full-density (approx. 20 returns/sq m) data was highly accurate (mean signed error of 0.19 +/-0.97 m), while those derived from reduced-density datasets (8/sq m, 4/sq m, 2/sq m and 1/sq m) were increasingly less accurate. Canopy heights calculated from reduced-density lidar data declined as data density decreased due to the inability to accurately model the terrain surface. For lidar return densities below 4/sq m, the bias in height estimates translated into errors of 80-125 Mg/ha in predicted aboveground biomass. Conclusions: Given the growing emphasis on the use of airborne lidar for forest management, carbon monitoring, and conservation efforts, the results of this study highlight the importance of careful survey planning and consistent sampling for accurate quantification of aboveground biomass stocks and dynamics. Approaches that rely primarily on canopy height to estimate aboveground biomass are sensitive to DTM errors from variability in lidar sampling density.

  8. On the vertical exchange of heat, mass and momentum over complex, mountainous terrain

    NASA Astrophysics Data System (ADS)

    Rotach, Mathias; Gohm, Alexander; Lang, Moritz; Leukauf, Daniel; Stiperski, Ivana; Wagner, Johannes

    2015-12-01

    The role of the atmospheric boundary layer (ABL) in the atmosphere-climate system is the exchange of heat, mass and momentum between 'the earth's surface' and the atmosphere. Traditionally, it is understood that turbulent transport is responsible for this exchange and hence the understanding and physical description of the turbulence structure of the boundary layer is key to assess the effectiveness of earth-atmosphere exchange. This understanding is rooted in the (implicit) assumption of a scale separation or spectral gap between turbulence and mean atmospheric motions, which in turn leads to the assumption of a horizontally homogeneous and flat (HHF) surface as a reference, for which both physical understanding and model parameterizations have successfully been developed over the years. Over mountainous terrain, however, the ABL is generically inhomogeneous due to both thermal (radiative) and dynamic forcing. This inhomogeneity leads to meso-scale and even sub-meso-scale flows such as slope and valley winds or wake effects. It is argued here that these (sub)meso-scale motions can significantly contribute to the vertical structure of the boundary layer and hence vertical exchange of heat and mass between the surface and the atmosphere. If model grid resolution is not high enough the latter will have to be parameterized (in a similar fashion as gravity wave drag parameterizations take into account the momentum transport due to gravity waves in large-scale models). In this contribution we summarize the available evidence of the contribution of (sub)meso-scale motions to vertical exchange in mountainous terrain from observational and numerical modeling studies. In particular, a number of recent simulation studies using idealized topography will be summarized and put into perspective – so as to identify possible limitations and areas of necessary future research.

  9. The biomechanics of walking shape the use of visual information during locomotion over complex terrain.

    PubMed

    Matthis, Jonathan Samir; Barton, Sean L; Fajen, Brett R

    2015-03-18

    The aim of this study was to examine how visual information is used to control stepping during locomotion over terrain that demands precision in the placement of the feet. More specifically, we sought to determine the point in the gait cycle at which visual information about a target is no longer needed to guide accurate foot placement. Subjects walked along a path while stepping as accurately as possible on a series of small, irregularly spaced target footholds. In various conditions, each of the targets became invisible either during the step to the target or during the step to the previous target. We found that making targets invisible after toe off of the step to the target had little to no effect on stepping accuracy. However, when targets disappeared during the step to the previous target, foot placement became less accurate and more variable. The findings suggest that visual information about a target is used prior to initiation of the step to that target but is not needed to continuously guide the foot throughout the swing phase. We propose that this style of control is rooted in the biomechanics of walking, which facilitates an energetically efficient strategy in which visual information is primarily used to initialize the mechanical state of the body leading into a ballistic movement toward the target foothold. Taken together with previous studies, the findings suggest the availability of visual information about the terrain near a particular step is most essential during the latter half of the preceding step, which constitutes a critical control phase in the bipedal gait cycle.

  10. The biomechanics of walking shape the use of visual information during locomotion over complex terrain

    PubMed Central

    Matthis, Jonathan Samir; Barton, Sean L.; Fajen, Brett R.

    2015-01-01

    The aim of this study was to examine how visual information is used to control stepping during locomotion over terrain that demands precision in the placement of the feet. More specifically, we sought to determine the point in the gait cycle at which visual information about a target is no longer needed to guide accurate foot placement. Subjects walked along a path while stepping as accurately as possible on a series of small, irregularly spaced target footholds. In various conditions, each of the targets became invisible either during the step to the target or during the step to the previous target. We found that making targets invisible after toe off of the step to the target had little to no effect on stepping accuracy. However, when targets disappeared during the step to the previous target, foot placement became less accurate and more variable. The findings suggest that visual information about a target is used prior to initiation of the step to that target but is not needed to continuously guide the foot throughout the swing phase. We propose that this style of control is rooted in the biomechanics of walking, which facilitates an energetically efficient strategy in which visual information is primarily used to initialize the mechanical state of the body leading into a ballistic movement toward the target foothold. Taken together with previous studies, the findings suggest the availability of visual information about the terrain near a particular step is most essential during the latter half of the preceding step, which constitutes a critical control phase in the bipedal gait cycle. PMID:25788704

  11. Important features of pollutant transport and diffusion in complex terrain/coastal settings revealed by airborne lidar

    SciTech Connect

    McElroy, J.L.; Smith, T.B.

    1994-12-31

    Our knowledge of transport and dispersion of air pollutants in complicated terrain or complex coastal/lakeshore settings is considerably less than that over simple, level terrain. This is largely because of induced microscale and mesoscale flows and lack of representative sites for ground-based monitors and inaccessibility for airborne in situ platforms. This knowledge, for instance, is required to improve the formulations of and validate air quality models, which in turn are used to develop strategies for alleviation of air pollution problems. Remote sensing devices, particularly those from aircraft or satellite platforms, have the capability of providing measurements with the requisite space and time detail for the understanding of the physical governing processes in such locales and also for improving and using air quality models for strategy development. One such device, the airborne lidar, has been widely used during field investigations to study pollutant distributions and attendant boundary layer structure and physical processes in relevant locales as various parts of Southern California. Each of these field investigations focussed on specific aspects or features of pollutant transport and diffusion. This paper summarizes pertinent and presents explicit examples of these aspects or features.

  12. Using High Resolution Regional Climate Models to Quantify the Snow Albedo Feedback in a Region of Complex Terrain

    NASA Astrophysics Data System (ADS)

    Letcher, T.; Minder, J. R.

    2015-12-01

    High resolution regional climate models are used to characterize and quantify the snow albedo feedback (SAF) over the complex terrain of the Colorado Headwaters region. Three pairs of 7-year control and pseudo global warming simulations (with horizontal grid spacings of 4, 12, and 36 km) are used to study how the SAF modifies the regional climate response to a large-scale thermodynamic perturbation. The SAF substantially enhances warming within the Headwaters domain, locally as much as 5 °C in regions of snow loss. The SAF also increases the inter-annual variability of the springtime warming within Headwaters domain under the perturbed climate. Linear feedback analysis is used quantify the strength of the SAF. The SAF attains a maximum value of 4 W m-2 K-1 during April when snow loss coincides with strong incoming solar radiation. On sub-seasonal timescales, simulations at 4 km and 12 km horizontal grid-spacing show good agreement in the strength and timing of the SAF, whereas a 36km simulation shows greater discrepancies that are tired to differences in snow accumulation and ablation caused by smoother terrain. An analysis of the regional energy budget shows that transport by atmospheric motion acts as a negative feedback to regional warming, damping the effects of the SAF. On the mesoscale, this transport causes non-local warming in locations with no snow. The methods presented here can be used generally to quantify the role of the SAF in other regional climate modeling experiments.

  13. A coupled remote sensing and the Surface Energy Balance with Topography Algorithm (SEBTA) to estimate actual evapotranspiration under complex terrain

    NASA Astrophysics Data System (ADS)

    Gao, Z. Q.; Liu, C. S.; Gao, W.; Chang, N. B.

    2010-07-01

    Evapotranspiration (ET) may be used as an ecological indicator to address the ecosystem complexity. The accurate measurement of ET is of great significance for studying environmental sustainability, global climate changes, and biodiversity. Remote sensing technologies are capable of monitoring both energy and water fluxes on the surface of the Earth. With this advancement, existing models, such as SEBAL, S_SEBI and SEBS, enable us to estimate the regional ET with limited temporal and spatial scales. This paper extends the existing modeling efforts with the inclusion of new components for ET estimation at varying temporal and spatial scales under complex terrain. Following a coupled remote sensing and surface energy balance approach, this study emphasizes the structure and function of the Surface Energy Balance with Topography Algorithm (SEBTA). With the aid of the elevation and landscape information, such as slope and aspect parameters derived from the digital elevation model (DEM), and the vegetation cover derived from satellite images, the SEBTA can fully account for the dynamic impacts of complex terrain and changing land cover in concert with some varying kinetic parameters (i.e., roughness and zero-plane displacement) over time. Besides, the dry and wet pixels can be recognized automatically and dynamically in image processing thereby making the SEBTA more sensitive to derive the sensible heat flux for ET estimation. To prove the application potential, the SEBTA was carried out to present the robust estimates of 24 h solar radiation over time, which leads to the smooth simulation of the ET over seasons in northern China where the regional climate and vegetation cover in different seasons compound the ET calculations. The SEBTA was validated by the measured data at the ground level. During validation, it shows that the consistency index reached 0.92 and the correlation coefficient was 0.87.

  14. Coupled snow dynamics, soil moisture, and soil temperatures in complex terrain of a semi-arid mountainous watershed

    NASA Astrophysics Data System (ADS)

    Bryden, S.; Link, T. E.; Seyfried, M. S.; McNamara, J. P.

    2011-12-01

    Mid-elevation regions characterized by transient or relatively brief seasonal snow covers are likely to experience large hydrologic impacts from warming trends as these regions transition from snow to rain-dominated precipitation in winter. These regions in the western United States are often comprised of complex terrain, including a range of slopes, aspects, elevation, vegetation, geology, and soils over multiple scales. How snow dynamics (e.g. distribution and timing) are coupled with soil moisture and soil temperature in complex terrain is a topic that needs to be explored in order to better understand how climate variations and trends will alter the hydrologic states and fluxes in these mid-elevation transition zones. To address this question, automated hydrometeorological stations were installed in Johnston Draw, a subbasin of the Reynolds Creek Experimental Watershed in southwestern Idaho. In addition to long-term precipitation records for the area, individual meteorological stations were installed on opposing north and south-facing slopes in the drainage at 50 meter elevation intervals, from 1550 to 1750 m amsl. Each station provides air temperature and vapor pressure, wind speed and direction, snow depth, and a profile of soil moisture and temperature at 5cm, 20cm, 35cm, and 50 cm depths, with some profiles extending to approximately 2 m where soils are deepest. Prior to a major mid-winter melt event in January 2011 snow depths averaged 45 cm on north-facing slopes and only 3 cm on south-facing slopes. Soil moisture was depleted near the surface and soil temperatures were just above freezing at all elevations and aspects. In mid-January, air temperatures rapidly increased from below freezing to daily averages from 3-6 °C for six consecutive days, coupled with very high wind speeds, and followed by a pulse of increased streamflow. This event completely ablated the snowpack on south-facing slopes and reduced the snowpack depth on north-facing slopes by 24 cm

  15. A Boundary-Layer Scaling Analysis Comparing Complex And Flat Terrain

    NASA Astrophysics Data System (ADS)

    Fitton, George; Tchiguirinskaia, Ioulia; Scherzter, Daniel; Lovejoy, Shaun

    2013-04-01

    A comparison of two boundary-layer (at approximately 50m) wind datasets shows the existence of reproducible scaling behaviour in two very topographically different sites. The first test site was in Corsica, an island in the South of France, subject to both orographic and convective effects due to its mountainous terrain and close proximity to the sea respectively. The data recorded in Corsica consisted of 10Hz sonic anemometer velocities measured over a six-month period. The second site consists of measurements from the Growian experiment. The testing site for this experiment was also in close proximity to the sea, however, the surrounding terrain is very flat. The data in this experiment was recorded using propellor anemometers at 2.5Hz. Note the resolution of the sonics was better, however, we found in both cases, using spectral methods, that the quality of the data was unusable below frequencies of one second. The scales that we will discuss therefore are from one second to fourteen hours. In both cases three scaling subranges are observed. Starting from the lower frequencies, both datasets have a spectral exponent of approximately two from six hours to fourteen hours. Our first scaling analyses were only done on the Corsica dataset and thus we proposed that this change in scaling was due to the orography. The steep slope of the hill on which the mast was positioned was causing the wind's orientation to be directed vertically. This implied that the vertical shears of the horizontal wind may scale as Bogiano-Obhukov's 11/5 power law. Further analysis on the second (Growian) dataset resulted in the same behaviour over the same time-scales. Since the Growian experiment was performed over nearly homogenous terrain our first hypothesis is questionable. Alternatively we propose that for frequencies above six hours Taylor's hypothesis is no longer valid. This implies that in order to observe the scaling properties of structures with eddy turnover times larger than six

  16. Simple sensors for performing useful tasks autonomously in complex outdoor terrain

    NASA Astrophysics Data System (ADS)

    Gat, Erann; Behar, Albert; Desai, Rajiv; Ivlev, Robert V.; Loch, John L.; Miller, David P.

    1992-11-01

    This paper describes the control system for Rocky IV, a prototype microrover designed to demonstrate proof-of-concept for a low-cost scientific mission to Mars. Rocky IV uses a behavior-based control architecture which implements a large variety of functions displaying various degrees of autonomy, from completely autonomous long-duration conditional sequences of actions to very precisely described actions resembling classical AI operators. The control system integrates information from infrared proximity sensors, proprioceptive encoders which report on the state of the articulation of the rover's suspension system and other mechanics, a homing beacon, a magnetic compass, and contact sensors. In addition, significant functionality is implemented as 'virtual sensors', computed values which are presented to the system as if they were sensors values. The robot is able to perform a variety of useful tasks, including soil sample collection, removal of surface weathering layers from rocks, spectral imaging, instrument deployment, and sample return, under realistic mission- like conditions in Mars-like terrain.

  17. Surface temperature lapse rates over complex terrain: Lessons from the Cascade Mountains

    NASA Astrophysics Data System (ADS)

    Minder, Justin R.; Mote, Philip W.; Lundquist, Jessica D.

    2010-07-01

    The typically sparse distribution of weather stations in mountainous terrain inadequately resolves temperature variability. Accordingly, high-resolution gridding of climate data (for applications such as hydrological modeling) often relies on assumptions such as a constant surface temperature lapse rate (i.e., decrease of surface temperature with altitude) of 6.5°C km-1. Using an example of the Cascade Mountains, we describe the temporal and spatial variability of the surface temperature lapse rate, combining data from: (1) COOP stations, (2) nearby radiosonde launches, (3) a temporary dense network of sensors, (4) forecasts from the MM5 regional model, and (5) PRISM geo-statistical analyses. On the windward side of the range, the various data sources reveal annual mean lapse rates of 3.9-5.2°C km-1, substantially smaller than the often-assumed 6.5°C km-1. The data sets show similar seasonal and diurnal variability, with lapse rates smallest (2.5-3.5°C km-1) in late-summer minimum temperatures, and largest (6.5-7.5°C km-1) in spring maximum temperatures. Geographic (windward versus lee side) differences in lapse rates are found to be substantial. Using a simple runoff model, we show the appreciable implications of these results for hydrological modeling.

  18. Effects of complex terrain on atmospheric flow: dividing streamline observations and quantification

    NASA Astrophysics Data System (ADS)

    Thompson, Michael; Fernando, Harindra; di Sabatino, Silvana; Leo, Laura; University of Notre Dame Team

    2013-11-01

    As part of the MATERHORN field campaign on atmospheric flow in mountainous terrain, the dividing streamline concept for stratified flow over obstacles was investigated using smoke flow visualization and meteorological measurements. At small Froude numbers (Fr < 1), a stratified flow approaching a mountain either possesses enough kinetic energy to pass over the summit or else flow around the sides, with dividing streamlines separating the two scenarios. An isolated northwestern peak of the Granite Mountain, approximately 60 m in height, was used for the study. Incoming flow velocities and temperature profiles were measured upstream using sonic anemometers and thermocouples mounted on a 32 m tower, while onsite measurements were taken with portable weather stations. Sufficiently strong stratification was developed around 3:00AM GMT, with Froude numbers in the range for dividing streamlines to exist. In the first trial, suitably placed red smoke releases were used and in another trial white smoke was released from a 25 m crane. In both cases well-defined dividing streamlines were observed and its vertical location was at a height about half of the mountain height, which is consistent with theoretical results based on Shepard's formula. This research was supported by the Office of Naval Research (ONR) grant number N00014-11-1-0709.

  19. Stratified Turbulence Measurements in Complex Terrain Using Hot-film Probes and a Collocated Sonic Anemometer

    NASA Astrophysics Data System (ADS)

    Hocut, C.; Kit, E.; Liberzon, D.; Fernando, H. J. S.; Materhorn Team

    2014-11-01

    In the fall of 2012 and spring 2013, the Mountain Terrain Atmospheric Modeling and Observations Program (MATERHORN) conducted extensive field experiments at the Granite Mountain Atmospheric Science Testbed (GMAST), US Army Dugway Proving Grounds (DPG), Utah. This provided a unique opportunity to deploy tower mounted three-dimensional hot-film combo probes, consisting of sonic anemometers collocated with hot-film anemometers able to respond to the wind direction. The combo probes follow mean winds using a feedback control loop and use a Neural Network to calibrate the hot-films in-situ. Once calibrated, these probes can handle a vast range of background flow conditions and scales from mesoscale flow down to the Kolmogorov scale. Of particular interest are the observed variation in velocity spectra during the evenings. Sometimes the velocity spectra shows the turbulence is Kolmogorov and is isotropic at small scales while in other spectra there is evidence of turbulence production at finer scales. An explanation on different spectral shapes will be presented as well as the relevant length/time scales of the production events. Funded by ONR Grant N00014-11-1-0709.

  20. Improved mapping of National Atmospheric Deposition Program wet-deposition in complex terrain using PRISM-gridded data sets

    USGS Publications Warehouse

    Latysh, Natalie E.; Wetherbee, Gregory Alan

    2012-01-01

    High-elevation regions in the United States lack detailed atmospheric wet-deposition data. The National Atmospheric Deposition Program/National Trends Network (NADP/NTN) measures and reports precipitation amounts and chemical constituent concentration and deposition data for the United States on annual isopleth maps using inverse distance weighted (IDW) interpolation methods. This interpolation for unsampled areas does not account for topographic influences. Therefore, NADP/NTN isopleth maps lack detail and potentially underestimate wet deposition in high-elevation regions. The NADP/NTN wet-deposition maps may be improved using precipitation grids generated by other networks. The Parameter-elevation Regressions on Independent Slopes Model (PRISM) produces digital grids of precipitation estimates from many precipitation-monitoring networks and incorporates influences of topographical and geographical features. Because NADP/NTN ion concentrations do not vary with elevation as much as precipitation depths, PRISM is used with unadjusted NADP/NTN data in this paper to calculate ion wet deposition in complex terrain to yield more accurate and detailed isopleth deposition maps in complex terrain. PRISM precipitation estimates generally exceed NADP/NTN precipitation estimates for coastal and mountainous regions in the western United States. NADP/NTN precipitation estimates generally exceed PRISM precipitation estimates for leeward mountainous regions in Washington, Oregon, and Nevada, where abrupt changes in precipitation depths induced by topography are not depicted by IDW interpolation. PRISM-based deposition estimates for nitrate can exceed NADP/NTN estimates by more than 100% for mountainous regions in the western United States.

  1. Estimating leaf-level parameters for ecosystem process models: a study in mixed conifer canopies on complex terrain.

    PubMed

    Duursma, Remko A; Marshall, John D; Nippert, Jesse B; Chambers, Chris C; Robinson, Andrew P

    2005-11-01

    Ecosystem process models are often used to predict carbon flux on a landscape or on a global scale. Such models must be aggregate and canopies are often treated as a uniform unit of foliage. Parameters that are known to vary within the canopy, e.g., nitrogen content and leaf mass per area, are often estimated by a mean value for the canopy. Estimating appropriate means is complicated, especially in mixed-species stands and in complex terrain. We analyzed sources of variation in specific parameters with the goal of testing various simplifying assumptions. The measurements came from mixed-species forests in the northern Rocky Mountains. We found that, for three important parameters (nitrogen concentration and content, and leaf mass per area), a sample taken near the vertical center of the crown provided a good estimate of the mean values for the crown. Altitude (700-1700 m), solar insolation (4200-5400 MJ m(-2) year(-1)) and leaf area index (1-11) had negligible effects on the parameters; only species differences were consistently detected. The correlation between mass-based photosynthetic rates and mass-based nitrogen concentrations was much weaker than the correlation between area-based photosynthetic rates and area-based nitrogen concentration. Comparison of photosynthesis-nitrogen relationships for a wide variety of conifer species and sites revealed a broad general trend that can be used in models. These results suggest important potential simplifications in model parameterization, most notably that canopy means can be estimated with ease, that complex terrain is a minor source of variation in these parameters and that use of one photosynthesis-nitrogen relationship for conifer species does not result in large errors. Species-to-species variation, however, was large and needs to be accounted for when parameterizing process models. PMID:16105802

  2. Variability of precipitation in complex terrain and the investigation of representativeness of measurements for the Matre catchment area, Western Norway.

    NASA Astrophysics Data System (ADS)

    Skjerdal, M.; Reuder, J.; Villanger, F.

    2009-04-01

    Orography is strongly affecting precipitation. Especially over complex terrain, the precipitation fields can show high spatial variability even over very small scales. Along the Western coast of Norway with its large precipitation amounts of up to above 3000 mm per year, an improved understanding of the spatial precipitation patterns is of large socio-economic impact, as it can improve both the prediction of floods and landslides and the water management for hydro power plants. The producers of hydroelectric power continuously want the water resources to be utilized in the best suited way. Control and supervision of the water resources are therefore of the utmost economic importance. To get an overview over the water resource situation, it is essential to know about the spatial and temporal distribution of precipitation. In cooperation with the Norwegian power company BKK, 20 HOBO rain gauges and two Aanderaa weather stations have been deployed between 22 and 898 meters above sea level in the catchment area for the Matre water system in Western Norway in the period May - October 2009. The main purpose of the project is to investigate the horizontal variability and the altitude dependence of precipitation in complex terrain under different synoptic conditions in this catchment area. Moreover, the representativeness of a few single point measurements on the total precipitation amount of the whole catchment area has been addressed. The total amount of precipitation recorded by the 20 rain gauges during the deployment period ranges between 535 mm and 1190 mm, which indicate the large variability within the catchment area. Analysis of the data with respect to wind direction shows that 75 % of the total precipitation amount during the measurement period arrives when the wind direction is S - SW. During a high precipitation event, which will be investigated in more detail, amounts of precipitation between 58 mm - 121 mm within a 24-hour period have been observed during a

  3. Coupled lagged ensemble weather- and river runoff prediction in complex Alpine terrain

    NASA Astrophysics Data System (ADS)

    Smiatek, Gerhard; Kunstmann, Harald; Werhahn, Johannes

    2013-04-01

    It is still a challenge to predict fast reacting streamflow precipitation response in Alpine terrain. Civil protection measures require flood prediction in 24 - 48 lead time. This holds particularly true for the Ammer River region which was affected by century floods in 1999, 2003 and 2005. Since 2005 a coupled NWP/Hydrology model system is operated in simulating and predicting the Ammer River discharges. The Ammer River catchment is located in the Bavarian Ammergau Alps and alpine forelands, Germany. With elevations reaching 2185 m and annual mean precipitation between 1100 and 2000 mm it represents very demanding test ground for a river runoff prediction system. The one way coupled system utilizes a lagged ensemble prediction system (EPS) taking into account combination of recent and previous NWP forecasts. The major components of the system are the MM5 NWP model run at 3.5 km resolution and initialized twice a day, the hydrology model WaSiM-ETH run at 100 m resolution and Perl object environment (POE) implementing the networking and the system operation. Results obtained in the years 2005-2012 reveal that river runoff simulations depict already high correlation (NSC in range 0.53 and 0.95) with observed runoff in retrospective runs with monitored meteorology data, but suffer from errors in quantitative precipitation forecast (QPF) from the employed numerical weather prediction model. We evaluate the NWP model accuracy, especially the precipitation intensity, frequency and location and put a focus on the performance gain of bias adjustment procedures. We show how this enhanced QFP data help to reduce the uncertainty in the discharge prediction. In addition to the HND (Hochwassernachrichtendienst, Bayern) observations TERENO Longterm Observatory hydrometeorological observation data are available since 2011. They are used to evaluate the NWP performance and setup of a bias correction procedure based on ensemble postprocessing applying Bayesian (BMA) model averaging

  4. Cause Resolving of Typhoon Precipitation Using Principle Component Analysis under Complex Interactive Effect of Terrain, Monsoon and Typhoon Vortex

    NASA Astrophysics Data System (ADS)

    Huang, C. L.; Hsu, N. S.

    2015-12-01

    This study develops a novel methodology to resolve the cause of typhoon-induced precipitation using principle component analysis (PCA) and to develop a long lead-time precipitation prediction model. The discovered spatial and temporal features of rainfall are utilized to develop a state-of-the-art descriptive statistical model which can be used to predict long lead-time precipitation during typhoons. The time series of 12-hour precipitation from different types of invasive moving track of typhoons are respectively precede the signal analytical process to qualify the causes of rainfall and to quantify affected degree of each induced cause. The causes include: (1) interaction between typhoon rain band and terrain; (2) co-movement effect induced by typhoon wind field with monsoon; (3) pressure gradient; (4) wind velocity; (5) temperature environment; (6) characteristic distance between typhoon center and surface target station; (7) distance between grade 7 storm radius and surface target station; and (8) relative humidity. The results obtained from PCA can detect the hidden pattern of the eight causes in space and time and can understand the future trends and changes of precipitation. This study applies the developed methodology in Taiwan Island which is constituted by complex diverse terrain formation and height. Results show that: (1) for the typhoon moving toward the direction of 245° to 330°, Causes (1), (2) and (6) are the primary ones to generate rainfall; and (2) for the direction of 330° to 380°, Causes (1), (4) and (6) are the primary ones. Besides, the developed precipitation prediction model by using PCA with the distributed moving track approach (PCA-DMT) is 32% more accurate by that of PCA without distributed moving track approach, and the former model can effectively achieve long lead-time precipitation prediction with an average predicted error of 13% within average 48 hours of forecasted lead-time.

  5. Effect of Coordinate Rotation Systems on Calculated Fluxes over a Forest in Complex Terrain: A Comprehensive Comparison

    NASA Astrophysics Data System (ADS)

    Shimizu, Takanori

    2015-08-01

    Seven coordinate rotation systems were compared to determine a suitable system for a forest in complex terrain, using eddy-covariance data for a period of 40 days. The traditional double rotation was set as the standard of comparison with six other fixed coordinate systems, whose coefficients were carefully determined based on wind component data for a two-year period. Differences in total heat fluxes and daytime fluxes calculated from all systems were small, except those from the sector-wise planar fit, which linearly and systematically underestimated the fluxes by about 5 %. The nighttime flux was also underestimated by the sector-wise planar fit, but there was significant scatter in the plots, and the mean difference was 7 %. The standard deviations of the wind components and scalars normalized by the friction velocity and the dynamic parameters were calculated for each system, and the errors from the relationships obtained previously from flat and homogenous terrain were examined. The nighttime normalized standard deviation for scalars agreed better with the relationships after applying the sector-wise planar fit than those calculated by the other systems, although no remarkable difference was found in the daytime data. Therefore, the sector-wise planar fit was not the first choice for our site during daytime based on the energy imbalance, which was mainly caused by underestimating daytime heat fluxes. Double rotation or one of the four systems without the roll rotation process might be superior at our site. However, the offset error in the vertical wind component of the sonic anemometer induced errors of several percent in the fluxes in these systems, which was equivalent to the underestimation using the sector-wise planar fit. Meanwhile, the sector-wise planar fit system might still be the best system for calculating nighttime flux, considering the tendency of the nighttime normalized standard deviations.

  6. Does complex terrain matter for global terrestrial ecosystem models? Forest ecosystem dynamics in the White Mountains, NH. (Invited)

    NASA Astrophysics Data System (ADS)

    Dietze, M. C.; Richardson, A. D.; Moorcroft, P. R.

    2010-12-01

    in valley-bottoms. A failure to include the effects of complex terrain is shown to result in a non-trivial overestimation of the net carbon sink. The model is then applied at a regional scale to forecast forest change under climate change scenarios. The addition of complex terrain is shown to buffer the effects of climate change on regional carbon fluxes. This effect occurs because climate change effects differ not only in magnitude but also in direction at a landscape-scale.

  7. Tactical Maneuvering and Calculated Risks: Independent Child Migrants and the Complex Terrain of Flight

    ERIC Educational Resources Information Center

    Denov, Myriam; Bryan, Catherine

    2012-01-01

    Similar to refugees in general, independent child migrants are frequently constructed in academic and popular discourse as passive and powerless or as untrustworthy and potentially threatening. Such portrayals fail to capture how these youth actively navigate the complex experiences of forced migration. Drawing on interviews with independent child…

  8. Modeling and measuring the nocturnal drainage flow in a high-elevation, subalpine forest with complex terrain

    USGS Publications Warehouse

    Yi, C.; Monson, Russell K.; Zhai, Z.; Anderson, D.E.; Lamb, B.; Allwine, G.; Turnipseed, A.A.; Burns, Sean P.

    2005-01-01

    The nocturnal drainage flow of air causes significant uncertainty in ecosystem CO2, H2O, and energy budgets determined with the eddy covariance measurement approach. In this study, we examined the magnitude, nature, and dynamics of the nocturnal drainage flow in a subalpine forest ecosystem with complex terrain. We used an experimental approach involving four towers, each with vertical profiling of wind speed to measure the magnitude of drainage flows and dynamics in their occurrence. We developed an analytical drainage flow model, constrained with measurements of canopy structure and SF6 diffusion, to help us interpret the tower profile results. Model predictions were in good agreement with observed profiles of wind speed, leaf area density, and wind drag coefficient. Using theory, we showed that this one-dimensional model is reduced to the widely used exponential wind profile model under conditions where vertical leaf area density and drag coefficient are uniformly distributed. We used the model for stability analysis, which predicted the presence of a very stable layer near the height of maximum leaf area density. This stable layer acts as a flow impediment, minimizing vertical dispersion between the subcanopy air space and the atmosphere above the canopy. The prediction is consistent with the results of SF6 diffusion observations that showed minimal vertical dispersion of nighttime, subcanopy drainage flows. The stable within-canopy air layer coincided with the height of maximum wake-to-shear production ratio. We concluded that nighttime drainage flows are restricted to a relatively shallow layer of air beneath the canopy, with little vertical mixing across a relatively long horizontal fetch. Insight into the horizontal and vertical structure of the drainage flow is crucial for understanding the magnitude and dynamics of the mean advective CO2 flux that becomes significant during stable nighttime conditions and are typically missed during measurement of the

  9. SToRM: A Model for Unsteady Surface Hydraulics Over Complex Terrain

    USGS Publications Warehouse

    Simoes, Francisco J.

    2014-01-01

    A two-dimensional (depth-averaged) finite volume Godunov-type shallow water model developed for flow over complex topography is presented. The model is based on an unstructured cellcentered finite volume formulation and a nonlinear strong stability preserving Runge-Kutta time stepping scheme. The numerical discretization is founded on the classical and well established shallow water equations in hyperbolic conservative form, but the convective fluxes are calculated using auto-switching Riemann and diffusive numerical fluxes. The model’s implementation within a graphical user interface is discussed. Field application of the model is illustrated by utilizing it to estimate peak flow discharges in a flooding event of historic significance in Colorado, U.S.A., in 2013.

  10. Horizontal heat fluxes over complex terrain computed using a simple mixed-layer model and a numerical model

    SciTech Connect

    Kimura, Fujio; Kuwagata, Tuneo

    1995-02-01

    The thermally induced local circulation over a periodic valley is simulated by a two-dimensional numerical model that does-not include condensational processes. During the daytime of a clear, calm day, heat is transported from the mountainous region to the valley area by anabatic wind and its return flow. The specific humidity is, however, transported in an inverse manner. The horizontal exchange rate of sensible heat has a horizontal scale similarity, as long as the horizontal scale is less than a critical width of about 100 km. The sensible heat accumulated in an atmospheric column over an arbitrary point can be estimated by a simple model termed the uniform mixed-layer model (UML). The model assumes that the potential temperature is both vertically and horizontally uniform in the mixed layer, even over the complex terrain. The UML model is valid only when the horizontal scale of the topography is less than the critical width and the maximum difference in the elevation of the topography is less than about 1500 m. Latent heat is accumulated over the mountainous region while the atmosphere becomes dry over the valley area. When the horizontal scale is close to the critical width, the largest amount of humidity is accumulated during the late afternoon over the mountainous region. 18 refs., 15 figs., 1 tab.

  11. Developing a high-resolution wind map for a complex terrain with a coupled MM5/CALMET system

    NASA Astrophysics Data System (ADS)

    Yim, Steve H. L.; Fung, Jimmy C. H.; Lau, Alexis K. H.; Kot, S. C.

    2007-03-01

    This study investigates the wind energy potential in Hong Kong, a region with a complex terrain, by coupling the prognostic MM5 mesoscale model with the CALMET diagnostic model to produce high-resolution wind fields. Hourly wind fields were simulated for the entire year of 2004. The MM5 simulations were performed on a nested grid from 40.5 km down to 1.5 km horizontal resolution. The CALMET meteorological model was used in a domain that includes the entire Hong Kong region with a high horizontal resolution of 100 m. The MM5 model wind field (1.5 km horizontal resolution) output was input into the CALMET diagnostic meteorological model every hour along with an objective analysis procedure using all available observations. Verification was achieved through two steps. In the first step, the data from three meteorological surface stations that were not assimilated into the CALMET model were compared horizontally with the simulated wind fields. In the second step, the simulated wind fields were compared vertically with the vertical wind profile collected from two upper air sounding stations. The results of this study identified the locations of the highest wind energy potential in HK down to 100 m resolution.

  12. Analysis of the long-term surface wind variability over complex terrain using a high spatial resolution WRF simulation

    NASA Astrophysics Data System (ADS)

    Jiménez, Pedro A.; González-Rouco, J. Fidel; Montávez, Juan P.; García-Bustamante, E.; Navarro, J.; Dudhia, J.

    2013-04-01

    This work uses a WRF numerical simulation from 1960 to 2005 performed at a high horizontal resolution (2 km) to analyze the surface wind variability over a complex terrain region located in northern Iberia. A shorter slice of this simulation has been used in a previous study to demonstrate the ability of the WRF model in reproducing the observed wind variability during the period 1992-2005. Learning from that validation exercise, the extended simulation is herein used to inspect the wind behavior where and when observations are not available and to determine the main synoptic mechanisms responsible for the surface wind variability. A principal component analysis was applied to the daily mean wind. Two principal modes of variation accumulate a large percentage of the wind variability (83.7%). The first mode reflects the channeling of the flow between the large mountain systems in northern Iberia modulated by the smaller topographic features of the region. The second mode further contributes to stress the differentiated wind behavior over the mountains and valleys. Both modes show significant contributions at the higher frequencies during the whole analyzed period, with different contributions at lower frequencies during the different decades. A strong relationship was found between these two modes and the zonal and meridional large scale pressure gradients over the area. This relationship is described in the context of the influence of standard circulation modes relevant in the European region like the North Atlantic Oscillation, the East Atlantic pattern, East Atlantic/Western Russia pattern, and the Scandinavian pattern.

  13. Statistical and Spectral Analysis of Wind Characteristics Relevant to Wind Energy Assessment Using Tower Measurements in Complex Terrain

    DOE PAGES

    Belu, Radian; Koracin, Darko

    2013-01-01

    The main objective of the study was to investigate spatial and temporal characteristics of the wind speed and direction in complex terrain that are relevant to wind energy assessment and development, as well as to wind energy system operation, management, and grid integration. Wind data from five tall meteorological towers located in Western Nevada, USA, operated from August 2003 to March 2008, used in the analysis. The multiannual average wind speeds did not show significant increased trend with increasing elevation, while the turbulence intensity slowly decreased with an increase were the average wind speed. The wind speed and direction weremore » modeled using the Weibull and the von Mises distribution functions. The correlations show a strong coherence between the wind speed and direction with slowly decreasing amplitude of the multiday periodicity with increasing lag periods. The spectral analysis shows significant annual periodicity with similar characteristics at all locations. The relatively high correlations between the towers and small range of the computed turbulence intensity indicate that wind variability is dominated by the regional synoptic processes. Knowledge and information about daily, seasonal, and annual wind periodicities are very important for wind energy resource assessment, wind power plant operation, management, and grid integration.« less

  14. Landscape variability of the stable carbon isotope composition of soil CO2 concentrations and flux in complex terrain

    NASA Astrophysics Data System (ADS)

    Riveros-Iregui, Diego; Liang, Liyin; Risk, David

    2015-04-01

    Stable isotopes are commonly used to understand how physical and biological processes mediate the exchange of carbon between terrestrial ecosystems and the atmosphere. Numerous studies have described fundamental relationships between environmental variables, the carbon isotopic composition (δ13C) of recently assimilated sugars in plants, litter, soil carbon, or recently respired CO2. However, studies that examine the landscape scale variability of the 13C content of forest soils are lacking. We report on measurements of the carbon isotopic composition of soil CO2 concentrations (δ13CC) and flux (δ13CJ) across a subalpine forest of the northern Rocky Mountains of Montana, United States. Our analysis demonstrates that soil moisture and the lateral redistribution of soil water are strong predictors of the spatial variability of both δ13CC and δ13CJ at the watershed scale. Our analysis suggests that there are concomitant yet independent effects of soil water on physical (i.e., soil gas diffusivity) and biological (i.e., photosynthetic activity) processes that mediate the 13C composition of forest soils. We show systematic spatial variability in the δ13C of forest soils at the landscape scale that can be useful to accurately predict and model land-atmosphere CO2 exchange over complex terrain.

  15. Complex mountain terrain and disturbance history drive variation in forest aboveground live carbon density in the western Oregon Cascades, USA

    PubMed Central

    Zald, Harold S.J.; Spies, Thomas A.; Seidl, Rupert; Pabst, Robert J.; Olsen, Keith A.; Steel, E. Ashley

    2016-01-01

    Forest carbon (C) density varies tremendously across space due to the inherent heterogeneity of forest ecosystems. Variation of forest C density is especially pronounced in mountainous terrain, where environmental gradients are compressed and vary at multiple spatial scales. Additionally, the influence of environmental gradients may vary with forest age and developmental stage, an important consideration as forest landscapes often have a diversity of stand ages from past management and other disturbance agents. Quantifying forest C density and its underlying environmental determinants in mountain terrain has remained challenging because many available data sources lack the spatial grain and ecological resolution needed at both stand and landscape scales. The objective of this study was to determine if environmental factors influencing aboveground live carbon (ALC) density differed between young versus old forests. We integrated aerial light detection and ranging (lidar) data with 702 field plots to map forest ALC density at a grain of 25 m across the H.J. Andrews Experimental Forest, a 6369 ha watershed in the Cascade Mountains of Oregon, USA. We used linear regressions, random forest ensemble learning (RF) and sequential autoregressive modeling (SAR) to reveal how mapped forest ALC density was related to climate, topography, soils, and past disturbance history (timber harvesting and wildfires). ALC increased with stand age in young managed forests, with much greater variation of ALC in relation to years since wildfire in old unmanaged forests. Timber harvesting was the most important driver of ALC across the entire watershed, despite occurring on only 23% of the landscape. More variation in forest ALC density was explained in models of young managed forests than in models of old unmanaged forests. Besides stand age, ALC density in young managed forests was driven by factors influencing site productivity, whereas variation in ALC density in old unmanaged forests

  16. The representation of location by regional climate models in complex terrain

    NASA Astrophysics Data System (ADS)

    Maraun, Douglas; Widmann, Martin

    2015-04-01

    To assess potential impacts of climate change for a specific location, one typically employs climate model simulations at the grid box corresponding to the same geographical location. But based on regional climate model simulations, we show that simulated climate might be systematically displaced compared to bservations. In particular in the rain shadow of moutain ranges, a local grid box is therefore often not representative of observed climate: the simulated windward weather does not flow far enough across the mountains; local grid boxes experience the wrong airmasses and atmospheric circulation. In some cases, also the local climate change signal is deteriorated. Classical bias correction methods fail to correct these location errors. Often, however, a distant simulated time series is representative of the considered observed precipitation, such that a non-local bias correction is possible. We illustrate the problem based on regional climate model simulations for Europe. Especially over complex topography such as the rain shadow of the Alps, local grid-box values often do not represent observed climate. A non-local bias correction, for the Alps based on simulated data from the windward side of the main mountain ridge, considerably improves the representation. These findings also clarify limitations of bias correcting global model errors, and of bias correction against station data.

  17. Feasibility of Estimating Snow Depth in Complex Terrain Using Satellite Lidar Altimetry

    NASA Technical Reports Server (NTRS)

    Jasinski, Michael F.; Stoll, Jeremy

    2012-01-01

    Satellite retrievals of snow depth and water equivalent (SWE) are critical for monitoring watershed scale processes around the world. However, the problem is especially challenging in mountainous regions where complex heterogeneities limit the utility of low resolution satellite sensors. The Geoscience Laser Altimeter Sensor (GLAS) aboard the Ice, Cloud, and land Elevation Satellite (ICESat) collected surface elevation data along near-repeat reference transects over land areas from 2003-2009. Although intended for monitoring ice caps and sea ice, the seven year global GLAS data base has provided unprecedented opportunity to test the capability of satellite lidar technology for estimating snow depth over land. GLAS single track and low repeat frequency does not provide data sufficient for operational estimates. However, its comparatively small footprint size of -65 m and its database of seasonal repeat observations during both snow and no-snow conditions have been sufficient to evaluate the potential of spacebased lidar altimetry for estimating snow depth. Recent analysis of ICESat elevations in the Uinta Mountains in NE Utah provide encouraging results for watershed scale estimates of snow depth. Research reported here focuses on the sensitivity of several versions of an ICESat snow depth algorithm to a range of landscape types defined by vegetation cover, slope and roughness. Results are compared to available SNOTEL data.

  18. Hydrologically-Aided Interpolation (HAI) of Precipitation in Complex Alpine Terrain

    NASA Astrophysics Data System (ADS)

    Riboust, P.; Le Moine, N.; Gailhard, J.; Hendrickx, F.; Garcon, R.; Gottardi, F.

    2015-12-01

    Hydrological modeling in mountainous regions requires unbiaised precipitation estimates at scales of a few hundreds to a few thousands square-kilometers (meso-scale). At these scales, precipitation patterns are complex and exhibit orographic enhancement, a phenomenon which is often poorly captured by scarce gage networks. Usually, the estimation of areal precipitation is performed independently of the hydrological modeling step (e.g. using precipitation reanalysis datasets or gage interpolation products). In this approach, it is not possible to easily correct precipitation biases in the case of discrepancies between observed and simulated discharges. In this study, we introduce the concept of Hydrologically-Aided Interpolation (HAI): a gage-based interpolation scheme, producing gridded daily precipitation estimates, is coupled to a semi-distributed hydrological model running at the daily time-step. The parameters of the interpolation scheme (precipitation gradients with elevation) are estimated jointly with the parameters of the hydrological model (snow scheme, soil moisture accounting scheme, and routing scheme). The whole hydrometeorological model is evaluated against cross-validation precipitation gages, point-scale snow water equivalent (SWE) measurements, and catchment-scale discharge estimates at several streamflow gaging sites in a 3,500 square-kilometer Alpine catchment in the French Southern Alps. Results show that adding hydrological constraints leads to much more robust estimates of precipitation gradients, which in turn produce improved precipitation estimates in temporal cross-validation both at point-scale and catchment-scale.

  19. Downscaling 20th century flooding events in complex terrain (Switzerland) using the WRF regional climate model

    NASA Astrophysics Data System (ADS)

    Heikkilä, Ulla; Gómez Navarro, Juan Jose; Franke, Jörg; Brönnimann, Stefan; Cattin, Réne

    2016-04-01

    Switzerland has experienced a number of severe precipitation events during the last few decades, such as during the 14-16 November of 2002 or during the 21-22 August of 2005. Both events, and subsequent extreme floods, caused fatalities and severe financial losses, and have been well studied both in terms of atmospheric conditions leading to extreme precipitation, and their consequences [e.g. Hohenegger et al., 2008, Stucki et al., 2012]. These examples highlight the need to better characterise the frequency and severity of flooding in the Alpine area. In a larger framework we will ultimately produce a high-resolution data set covering the entire 20th century to be used for detailed hydrological studies including all atmospheric parameters relevant for flooding events. In a first step, we downscale the aforementioned two events of 2002 and 2005 to assess the model performance regarding precipitation extremes. The complexity of the topography in the Alpine area demands high resolution datasets. To achieve a sufficient detail in resolution we employ the Weather Research and Forecasting regional climate model (WRF). A set of 4 nested domains is used with a 2-km resolution horizontal resolution over Switzerland. The NCAR 20th century reanalysis (20CR) with a horizontal resolution of 2.5° serves as boundary condition [Compo et al., 2011]. First results of the downscaling the 2002 and 2005 extreme precipitation events show that, compared to station observations provided by the Swiss Meteorological Office MeteoSwiss, the model strongly underestimates the strength of these events. This is mainly due to the coarse resolution of the 20CR data, which underestimates the moisture fluxes during these events. We tested driving WRF with the higher-resolved NCEP reanalysis and found a significant improvement in the amount of precipitation of the 2005 event. In a next step we will downscale the precipitation and wind fields during a 6-year period 2002-2007 to investigate and

  20. Periglacial complexes in Utopia Planitia: rimless, tiered depressions, (clastically) sorted and unsorted polygonised terrain and an ice-rich mantle

    NASA Astrophysics Data System (ADS)

    Soare, Richard; Conway, Susan; Gallagher, Colman; Dohm, James; Clifford, Stephen M.; Williams, Jean-pierre

    2016-10-01

    We report the spatial and possible genetic-relationship at the mid-latitudes of Utopia Planitia (45-500N 115-1200E), Mars, of: (a) metre to decametre deep, rimless, tiered depressions; terrain that exhibits (b) (clastically) sorted and (c) unsorted (small-sized) polygons; and, (d) a very youthful, ice-rich mantle. We show that these individual landscape features are separated stratigraphically, this being presented to the Mars community for the first time, and suggest that the stratigraphical separation of these features could be the result of boundary conditions and formation processes that have varied much more widely than has been thought hitherto. In cold-climate and non-glacial regions such as the Yamal Peninsula of eastern Russia and the Tuktoyaktuk Coastlands of northern Canada, landscape assemblages comprised of similar features are referenced as "ice complexes" and are indicative of periglacialism on two fronts: first, the presence of "ice-rich" permafrost or permafrost comprised of "excess ice", i.e. "permafrost" whose pore space is exceeded by the "water ice" within that body of sediment; and, second, antecedently or currently active freeze-thaw cycling, minimally, to the full depth of the "ice-complex" depressions. In the Dry Valleys of the Antarctic, where the atmospheric aridity and cold-temperatures approach those of Mars, ice-vapour diffusion and adsorption cycles are cited as the means by which the near-surface, permafrost, i.e. ≤1m deep, has become ice-cemented. However, the metre to decametre depths of the "ice-complex" depressions on Earth and the morphologically-similar ones on Mars lie beyond the vertical reach of the Antarctic diffusion and adsorption cycles, both empirically and theoretically. By deduction, this points to the freeze-thaw cycling of water to depth, fostered either by exogenic or endogenic means, perhaps playing a more important role in the formation of the possible Martian "ice complexes" than might be expected were

  1. Methodological approach in determination of small spatial units in a highly complex terrain in atmospheric pollution research: the case of Zasavje region in Slovenia.

    PubMed

    Kukec, Andreja; Boznar, Marija Z; Mlakar, Primoz; Grasic, Bostjan; Herakovic, Andrej; Zadnik, Vesna; Zaletel-Kragelj, Lijana; Farkas, Jerneja; Erzen, Ivan

    2014-05-01

    The study of atmospheric air pollution research in complex terrains is challenged by the lack of appropriate methodology supporting the analysis of the spatial relationship between phenomena affected by a multitude of factors. The key is optimal design of a meaningful approach based on small spatial units of observation. The Zasavje region, Slovenia, was chosen as study area with the main objective to investigate in practice the role of such units in a test environment. The process consisted of three steps: modelling of pollution in the atmosphere with dispersion models, transfer of the results to geographical information system software, and then moving on to final determination of the function of small spatial units. A methodology capable of designing useful units for atmospheric air pollution research in highly complex terrains was created, and the results were deemed useful in offering starting points for further research in the field of geospatial health.

  2. Evaluation of AERMOD and CALPUFF for predicting ambient concentrations of total suspended particulate matter (TSP) emissions from a quarry in complex terrain.

    PubMed

    Tartakovsky, Dmitry; Broday, David M; Stern, Eli

    2013-08-01

    Concentrations of particulate emissions from a quarry located in hilly terrain were calculated by two common atmospheric dispersion models, AERMOD and CALPUFF. Evaluation of these models for emissions from quarries/open pit mines that are located in complex topography is missing from the literature. Due to severe uncertainties in the input parameters, numerous scenarios were simulated and model sensitivity was studied. Model results were compared among themselves, and to measured total suspended particulate (TSP). For a wide range of meteorological and topographical conditions studied, AERMOD predictions were in a better agreement with the measurements than those obtained by CALPUFF. The use of AERMOD's "Open pit" tool seems unnecessary when accurate digital topographic data are available. Onsite meteorological data are shown to be crucial for reliable dispersion calculations in complex terrain.

  3. Atmospheric and dispersion modeling in areas of highly complex terrain employing a four-dimensional data assimilation technique

    SciTech Connect

    Fast, J.D.; O`Steen, B.L.

    1994-12-31

    The results of this study indicate that the current data assimilation technique can have a positive impact on the mesoscale flow fields; however, care must be taken in its application to grids of relatively fine horizontal resolution. Continuous FDDA is a useful tool in producing high-resolution mesoscale analysis fields that can be used to (1) create a better initial conditions for mesoscale atmospheric models and (2) drive transport models for dispersion studies. While RAMS is capable of predicting the qualitative flow during this evening, additional experiments need to be performed to improve the prognostic forecasts made by RAMS and refine the FDDA procedure so that the overall errors are reduced even further. Despite the fact that a great deal of computational time is necessary in executing RAMS and LPDM in the configuration employed in this study, recent advances in workstations is making applications such as this more practical. As the speed of these machines increase in the next few years, it will become feasible to employ prognostic, three-dimensional mesoscale/transport models to routinely predict atmospheric dispersion of pollutants, even to highly complex terrain. For example, the version of RAMS in this study could be run in a ``nowcasting`` model that would continually assimilate local and regional observations as soon as they become available. The atmospheric physics in the model would be used to determine the wind field where no observations are available. The three-dimensional flow fields could be used as dynamic initial conditions for a model forecast. The output from this type of modeling system will have to be compared to existing diagnostic, mass-consistent models to determine whether the wind field and dispersion forecasts are significantly improved.

  4. Saturation sampling for spatial variation in multiple air pollutants across an inversion-prone metropolitan area of complex terrain

    PubMed Central

    2014-01-01

    Background Characterizing intra-urban variation in air quality is important for epidemiological investigation of health outcomes and disparities. To date, however, few studies have been designed to capture spatial variation during select hours of the day, or to examine the roles of meteorology and complex terrain in shaping intra-urban exposure gradients. Methods We designed a spatial saturation monitoring study to target local air pollution sources, and to understand the role of topography and temperature inversions on fine-scale pollution variation by systematically allocating sampling locations across gradients in key local emissions sources (vehicle traffic, industrial facilities) and topography (elevation) in the Pittsburgh area. Street-level integrated samples of fine particulate matter (PM2.5), black carbon (BC), nitrogen dioxide (NO2), sulfur dioxide (SO2), and ozone (O3) were collected during morning rush and probable inversion hours (6-11 AM), during summer and winter. We hypothesized that pollution concentrations would be: 1) higher under inversion conditions, 2) exacerbated in lower-elevation areas, and 3) vary by season. Results During July - August 2011 and January - March 2012, we observed wide spatial and seasonal variability in pollution concentrations, exceeding the range measured at regulatory monitors. We identified elevated concentrations of multiple pollutants at lower-elevation sites, and a positive association between inversion frequency and NO2 concentration. We examined temporal adjustment methods for deriving seasonal concentration estimates, and found that the appropriate reference temporal trend differs between pollutants. Conclusions Our time-stratified spatial saturation approach found some evidence for modification of inversion-concentration relationships by topography, and provided useful insights for refining and interpreting GIS-based pollution source indicators for Land Use Regression modeling. PMID:24735818

  5. Comparison of Measured and WRF-LES Turbulence Statistics in a Real Convective Boundary Layer over Complex Terrain

    NASA Astrophysics Data System (ADS)

    Rai, R. K.; Berg, L. K.; Kosovic, B.; Mirocha, J. D.; Pekour, M. S.; Shaw, W. J.

    2015-12-01

    Resolving the finest turbulent scales present in the lower atmosphere using numerical simulations helps to study the processes that occur in the atmospheric boundary layer, such as the turbulent inflow condition to the wind plant and the generation of the wake behind wind turbines. This work employs several nested domains in the WRF-LES framework to simulate conditions in a convectively driven cloud free boundary layer at an instrumented field site in complex terrain. The innermost LES domain (30 m spatial resolution) receives the boundary forcing from two other coarser resolution LES outer domains, which in turn receive boundary conditions from two WRF-mesoscale domains. Wind and temperature records from sonic anemometers mounted at two vertical levels (30 m and 60 m) are compared with the LES results in term of first and second statistical moments as well as power spectra and distributions of wind velocity. For the two mostly used boundary layer parameterizations (MYNN and YSU) tested in the WRF mesoscale domains, the MYNN scheme shows slightly better agreement with the observations for some quantities, such as time averaged velocity and Turbulent Kinetic Energy (TKE). However, LES driven by WRF-mesoscale simulations using either parameterization have similar velocity spectra and distributions of velocity. For each component of the wind velocity, WRF-LES power spectra are found to be comparable to the spectra derived from the measured data (for the frequencies that are accurately represented by WRF-LES). Furthermore, the analysis of LES results shows a noticeable variability of the mean and variance even over small horizontal distances that would be considered sub-grid scale in mesoscale simulations. This observed statistical variability in space and time can be utilized to further analyze the turbulence quantities over a heterogeneous surface and to improve the turbulence parameterization in the mesoscale model.

  6. Accuracy of retrieving temperature and humidity profiles by ground-based microwave radiometry in truly complex terrain

    NASA Astrophysics Data System (ADS)

    Massaro, G.; Stiperski, I.; Pospichal, B.; Rotach, M. W.

    2015-08-01

    Within the Innsbruck Box project, a ground-based microwave radiometer (RPG-HATPRO) was operated in the Inn Valley (Austria), in very complex terrain, between September 2012 and May 2013 to obtain temperature and humidity vertical profiles of the full troposphere with a specific focus on the valley boundary layer. In order to assess its performance in a deep alpine valley, the profiles obtained by the radiometer with different retrieval algorithms based on different climatologies are compared to local radiosonde data. A retrieval that is improved with respect to the one provided by the manufacturer, based on better resolved data, shows a significantly smaller root mean square error (RMSE), both for the temperature and humidity profiles. The improvement is particularly substantial at the heights close to the mountaintop level and in the upper troposphere. Lower-level inversions, common in an alpine valley, are resolved to a satisfactory degree. On the other hand, upper-level inversions (above 1200 m) still pose a significant challenge for retrieval. For this purpose, specialized retrieval algorithms were developed by classifying the radiosonde climatologies into specialized categories according to different criteria (seasons, daytime, nighttime) and using additional regressors (e.g., measurements from mountain stations). The training and testing on the radiosonde data for these specialized categories suggests that a classification of profiles that reproduces meaningful physical characteristics can yield improved targeted specialized retrievals. A novel and very promising method of improving the profile retrieval in a mountainous region is adding further information in the retrieval, such as the surface temperature at fixed levels along a topographic slope or from nearby mountaintops.

  7. Amazon Rainforest Exchange of Carbon and Subcanopy Air Flow: Manaus LBA Site—A Complex Terrain Condition

    PubMed Central

    Tóta, Julio; Roy Fitzjarrald, David; da Silva Dias, Maria A. F.

    2012-01-01

    On the moderately complex terrain covered by dense tropical Amazon Rainforest (Reserva Biologica do Cuieiras—ZF2—02°36′17.1′′ S, 60°12′24.4′′ W), subcanopy horizontal and vertical gradients of the air temperature, CO2 concentration and wind field were measured for the dry and wet periods in 2006. We tested the hypothesis that horizontal drainage flow over this study area is significant and can affect the interpretation of the high carbon uptake rates reported by previous works at this site. A similar experimental design as the one by Tóta et al. (2008) was used with a network of wind, air temperature, and CO2 sensors above and below the forest canopy. A persistent and systematic subcanopy nighttime upslope (positive buoyancy) and daytime downslope (negative buoyancy) flow pattern on a moderately inclined slope (12%) was observed. The microcirculations observed above the canopy (38 m) over the sloping area during nighttime presents a downward motion indicating vertical convergence and correspondent horizontal divergence toward the valley area. During the daytime an inverse pattern was observed. The micro-circulations above the canopy were driven mainly by buoyancy balancing the pressure gradient forces. In the subcanopy space the microcirculations were also driven by the same physical mechanisms but probably with the stress forcing contribution. The results also indicated that the horizontal and vertical scalar gradients (e.g., CO2) were modulated by these micro-circulations above and below the canopy, suggesting that estimates of advection using previous experimental approaches are not appropriate due to the tridimensional nature of the vertical and horizontal transport locally. This work also indicates that carbon budget from tower-based measurement is not enough to close the system, and one needs to include horizontal and vertical advection transport of CO2 into those estimates. PMID:22619608

  8. An Overview of MADONA: A Multinational Field Study of High-Resolution Meteorology and Diffusion over Complex Terrain.

    NASA Astrophysics Data System (ADS)

    Cionco, R. M.; Byers, J. H.; Aufm Kampe, W.; van Raden, H.; Weber, H.; Biltoft, C.; Collins, C. G.; Higgs, T. J.; Jones, C. D.; Ride, D. J.; Robson, R.; Hin, A. R. T.; Johansson, P.-E.; Nyrén, K.; Jørgensen, H. E.; Mikkelsen, T.; Santabarbara, J. M.; Thykier-Nielsen, S.; Kimber, J. F.; Streicher, J.

    1999-01-01

    The multination, high-resolution field study of Meteorology And Diffusion Over Non-Uniform Areas (MADONA) was conducted by scientists from the United States, the United Kingdom, Germany, Denmark, Sweden, and the Netherlands at Porton Down, Salisbury, Wiltshire, United Kingdom, during September and October 1992. The host of the field study was the Chemical and Biological Defence Establishment (CBDE, now part of Defence Evaluation and Research Agency) at Porton Down. MADONA was designed and conducted for high-resolution meteorological data collection and diffusion experiments using smoke, sulphurhexaflouride (SF6), and propylene gas during unstable, neutral, and stable atmospheric conditions in an effort to obtain terrain-influenced meteorological fields, dispersion, and concentration fluctuation measurements using specialized sensors and tracer generators. Thirty-one days of meteorological data were collected during the period 7 September-7 October and 27 diffusion experiments were conducted from 14 to 23 September 1992. Puffs and plumes of smoke and SF6 were released simultaneously for most of the experiments to gauge the resultant diffusion and concentration behavior. Some 44 meteorological and aerosol sensors and four source generators were used during each day of the field study. This array of sensors included 14 towers of wind cups and vanes, 10 sonic anemometer/thermometers, one boundary layer sonde, two lidar, one ion sensor, the CBDE Weather Station, and several one-of-a-kind sensors. Simulations of airflow and diffusion over the MADONA topography (a 9 km by 7.5 km area) were made with a variety of models. Wind fields and wind-related parameters were simulated with several high-resolution (microalpha scale) wind flow models. A tally of the various data-gathering activities indicates that the execution of MADONA was highly successful. Preliminary use of the datasets shows the high quality and depth of the MADONA database. This well-documented database is

  9. Quantifying evaporation and transpiration fluxes of an Eucalyptus woodland in complex terrain with varying tree cover using the Maximum Entropy Production model of evapotranspiration

    NASA Astrophysics Data System (ADS)

    Gutierrez-Jurado, H. A.; Guan, H.; Wang, H.; Wang, J.; Bras, R. L.; Simmons, C. T.

    2013-12-01

    The measurement of evapotranspiration (ET) fluxes in areas with complex terrain and non-uniform vegetation cover pose a challenge to traditional techniques with fetch constraints, such as the Eddy Covariance method. In this study, we report the results of a field monitoring design based on the Maximum Entropy Production model of ET (MEP-ET), that quantifies evaporation and transpiration from soil and vegetation respectively, using a limited number of measurements of temperature, humidity and net radiation above soil and canopies. Following the MEP-ET model requirements we instrumented a catchment with complex terrain and native vegetation (Eucalyptus leucoxylon) in South Australia. We deployed vertical-through-canopy and near-soil temperature and humidity transects in two opposing slopes (north and south facing) with contrasting canopy cover and understory conditions to measure tree transpiration from 2 eucalyptus trees and soil evaporation of the area under their canopies. We compare the results with transpiration measurements from sapflow data on the same trees and soil evaporation estimates with the Bowen Ratio Energy Balance (BREB) method. Our results show good agreement between the MEP-ET derived transpiration and evaporation and the sapflow transpiration and BREB evaporation estimates, respectively. Using a LiDAR derived canopy cover we upscale the MEP-ET fluxes on each slope and explore the effect of terrain and vegetation cover on the partition of ET and the water budgets across the catchment.

  10. Chaotic Terrain

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Released 4 June 2003

    Chaotic terrain on Mars is thought to form when there is a sudden removal of subsurface water or ice, causing the surface material to slump and break into blocks. The chaotic terrain in this THEMIS visible image is confined to a crater just south of Elysium Planitia. It is common to see chaotic terrain in the vicinity of the catastrophic outflow channels on Mars, but the terrain in this image is on the opposite side of the planet from these channels, making it somewhat of an oddity.

    Image information: VIS instrument. Latitude -5.9, Longitude 108.1 East (251.9 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  11. Polar Terrains

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03577 Polar Terrains

    The region surrounding the South Polar Cap contains many different terrain types. This image shows both etched terrain and a region of 'mounds'.

    Image information: VIS instrument. Latitude 75S, Longitude 286.5E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  12. Short-term emergency response planning and risk assessment via an integrated modeling system for nuclear power plants in complex terrain

    NASA Astrophysics Data System (ADS)

    Chang, Ni-Bin; Weng, Yu-Chi

    2013-03-01

    Short-term predictions of potential impacts from accidental release of various radionuclides at nuclear power plants are acutely needed, especially after the Fukushima accident in Japan. An integrated modeling system that provides expert services to assess the consequences of accidental or intentional releases of radioactive materials to the atmosphere has received wide attention. These scenarios can be initiated either by accident due to human, software, or mechanical failures, or from intentional acts such as sabotage and radiological dispersal devices. Stringent action might be required just minutes after the occurrence of accidental or intentional release. To fulfill the basic functions of emergency preparedness and response systems, previous studies seldom consider the suitability of air pollutant dispersion models or the connectivity between source term, dispersion, and exposure assessment models in a holistic context for decision support. Therefore, the Gaussian plume and puff models, which are only suitable for illustrating neutral air pollutants in flat terrain conditional to limited meteorological situations, are frequently used to predict the impact from accidental release of industrial sources. In situations with complex terrain or special meteorological conditions, the proposing emergency response actions might be questionable and even intractable to decisionmakers responsible for maintaining public health and environmental quality. This study is a preliminary effort to integrate the source term, dispersion, and exposure assessment models into a Spatial Decision Support System (SDSS) to tackle the complex issues for short-term emergency response planning and risk assessment at nuclear power plants. Through a series model screening procedures, we found that the diagnostic (objective) wind field model with the aid of sufficient on-site meteorological monitoring data was the most applicable model to promptly address the trend of local wind field patterns

  13. Improving ozone modeling in complex terrain at a fine grid resolution: Part I - examination of analysis nudging and all PBL schemes associated with LSMs in meteorological model

    NASA Astrophysics Data System (ADS)

    Kim, Yunhee; Fu, Joshua S.; Miller, Terry L.

    2010-02-01

    Meteorological variables such as temperature, wind speed, wind directions, and Planetary Boundary Layer (PBL) heights have critical implications for air quality simulations. Sensitivity simulations with five different PBL schemes associated with three different Land Surface Models (LSMs) were conducted to examine the impact of meteorological variables on the predicted ozone concentrations using the Community Multiscale Air Quality (CMAQ) version 4.5 with local perspective. Additionally, the nudging analysis for winds was adopted with three different coefficients to improve the wind fields in the complex terrain at 4-km grid resolution. The simulations focus on complex terrain having valley and mountain areas at 4-km grid resolution. The ETA M-Y (Mellor-Yamada) and G-S (Gayno-Seaman) PBL schemes are identified as favorite options and promote O 3 formation causing the higher temperature, slower winds, and lower mixing height among sensitivity simulations in the area of study. It is found that PX (Pleim-Xiu) simulation does not always give optimal meteorological model performance. We also note that the PBL scheme plays a more important role in predicting daily maximum 8-h O 3 than land surface models. The results of nudging analysis for winds with three different increased coefficients' values (2.5, 4.5, and 6.0 × 10 -4 s -1) over seven sensitivity simulations show that the meteorological model performance was enhanced due to improved wind fields, indicating the FDDA nudging analysis can improve model performance considerably at 4-km grid resolution. Specifically, the sensitivity simulations with the coefficient value (6.0 × 10 -4) yielded more substantial improvements than with the other values (2.5 and 4.5 × 10 -4). Hence, choosing the nudging coefficient of 6.0 × 10 -4 s -1 for winds in MM5 may be the best choice to improve wind fields as an input, as well as, better model performance of CMAQ in the complex terrain area. As a result, a finer grid resolution is

  14. An examination of the relationships between selected ground properties and Landsat MSS data in an area of complex terrain in southern Italy

    NASA Technical Reports Server (NTRS)

    Justice, C. O.

    1978-01-01

    The paper deals with the method and results of a study which involved an examination of the statistical relationships between selected ground properties and Landsat MSS data, and whose aim was to assess the applicability of Landsat data to surface cover mapping in areas characterized by high-frequency spatial variations of surface cover type over small areas. The results indicate that by systematic ground data collection it is possible to understand the basic relationships between ground properties and Landsat sensor data in areas of complex surface cover and terrain, and to classify the cover types.

  15. Impact of resolution on regional climate modeling in the source region of Yellow River with complex terrain using RegCM3

    NASA Astrophysics Data System (ADS)

    Hui, Pinhong; Tang, Jianping; Wang, Shuyu; Wu, Jian; Niu, Xiaorui; Kang, Yue

    2016-07-01

    This paper presents results from a 20-year (1990-2009) simulation by RegCM3 with both 45- and 15-km horizontal resolutions. The research focuses on the source region of Yellow River and its surrounding area, which is located on the northeast edge of the Tibetan Plateau with its very complex topography. Driven by the ECMWF ERA-interim reanalysis data, RegCM3 displays reasonable ability to reproduce the spatial patterns, annual cycles, and the interannual variabilities of regional surface climate, though the model shows wet and cold bias. The model's performance is more close to observation for the source region of Yellow River than the other part of the analysis region, and the application of high resolution of 15 km demonstrates better skill with less bias for mean climate and larger correlation coefficients for interannual variability at most stations. However, the high-resolution simulation shows little advantage for reproducing the variations of precipitation and surface air temperature with altitude. The RegCM3 model also generally reproduces the probability distribution functions (PDFs) of surface climate and, consequently, the occurrence of climatic extremes and extreme indices. The simulation with high resolution again proves to be more reliable to generate climatic extremes over complex terrain of the source region of the Yellow River, related to its better representation of complex terrain and local processes.

  16. An Analysis of Unique Aerial Photographs of Atmospheric Eddies in Marine Stratocumulus Clouds Downwind of Complex Terrain Along the California Coast

    NASA Astrophysics Data System (ADS)

    Muller, B. M.; Herbster, C. G.; Mosher, F. R.

    2013-12-01

    Unique aerial photographs of atmospheric eddies in marine stratocumulus clouds downwind of complex terrain along the California coast are presented and analyzed. While satellite imagery of similar eddies have appeared in the scientific literature since the 1960's, it is believed that these are the first close-up photographs of such eddies, taken from an airplane, to appear in publication. Two photographs by a commercial pilot, flying California coastal routes, are presented: one from July 16, 2006 downwind of Santa Cruz Island, a 740 m peak bordering the Santa Barbara Channel off the California coast; and one from September 12, 2006 near Grover Beach, California, downwind of a headland containing the San Luis Range, a region of complex terrain near San Luis Obispo, California, with ridges ranging approximately from 240 to 550 m elevation. Both eddies occurred in the lee of inversion-penetrating terrain, and were marked by a cyclonic vortex in the clouds with a striking cloud-free 'eye' feature roughly 3 km in diameter. The Santa Cruz Island eddy was 25 km in length and 9-10 km in width, while the Grover Beach eddy was 17 km in length and had a width of 9 km, placing it in the meso-gamma scale of atmospheric features. GOES (Geostationary Operational Environmental Satellite) imagery for both cases was obtained and help to define the lifecycle and motions of the eddies captured in the snapshots. Relevant meteorological observations for the Santa Cruz Island eddy were not located, but in-situ observations from the Diablo Canyon Nuclear Power Plant, California Polytechnic State University (Cal Poly) pier, and the San Luis Obispo County Air Pollution Control District, made possible a more detailed examination of the Grover Beach eddy and its structure. Additionally, we offer speculation on an eddy formation mechanism consistent with the satellite and in-situ observations described in this presentation, and hypotheses from the literature on low Froude number, continuously

  17. Miranda's Geologic History (variety of terrain)

    NASA Technical Reports Server (NTRS)

    1986-01-01

    Miranda reveals a complex geologic history in this view, acquired by Voyager 2 on Jan. 24, 1986, around its close approach to the Uranian moon. At least three terrain types of different age and geologic style are evident at this resolution of about 700 meters (2,300 feet). Visible in this clear-filter, narrow-angle image are, from left: (1) an apparently ancient, cratered terrain consisting of rolling, subdued hills and degraded medium-sized craters (2) a grooved terrain with linear valleys and ridges developed at the expense of, or replacing, the first terrain type: and (3) a complex terrain seen along the terminator, in which intersecting curvilinear ridges and troughs are abruptly truncated by the linear, grooved terrain. Voyager scientists believe this third terrain type is intermediate in age between the first two. The Voyager project is managed for NASA by the Jet Propulsion Laboratory.

  18. Integrating Map Algebra and Statistical Modeling for Spatio-Temporal Analysis of Monthly Mean Daily Incident Photosynthetically Active Radiation (PAR) over a Complex Terrain

    PubMed Central

    Evrendilek, Fatih

    2007-01-01

    This study aims at quantifying spatio-temporal dynamics of monthly mean daily incident photosynthetically active radiation (PAR) over a vast and complex terrain such as Turkey. The spatial interpolation method of universal kriging, and the combination of multiple linear regression (MLR) models and map algebra techniques were implemented to generate surface maps of PAR with a grid resolution of 500 × 500 m as a function of five geographical and 14 climatic variables. Performance of the geostatistical and MLR models was compared using mean prediction error (MPE), root-mean-square prediction error (RMSPE), average standard prediction error (ASE), mean standardized prediction error (MSPE), root-mean-square standardized prediction error (RMSSPE), and adjusted coefficient of determination (R2adj.). The best-fit MLR- and universal kriging-generated models of monthly mean daily PAR were validated against an independent 37-year observed dataset of 35 climate stations derived from 160 stations across Turkey by the Jackknifing method. The spatial variability patterns of monthly mean daily incident PAR were more accurately reflected in the surface maps created by the MLR-based models than in those created by the universal kriging method, in particular, for spring (May) and autumn (November). The MLR-based spatial interpolation algorithms of PAR described in this study indicated the significance of the multifactor approach to understanding and mapping spatio-temporal dynamics of PAR for a complex terrain over meso-scales.

  19. Resolving extreme rainfall from space: a new class of algorithms for precipitation retrieval over radiometrically complex terrain and coastal areas

    NASA Astrophysics Data System (ADS)

    Foufoula-Georgiou, Efi; Ebtehaj, Mohammad

    2016-04-01

    The increasing availability of precipitation observations from the Global Precipitation Measuring (GPM) Mission, has fueled renewed interest in developing frameworks for accurate estimation of precipitation extremes especially over ungauged mountainous terrains and coastal regions to improve hydro-geological hazard prediction and control. Our recent research has shown that treating precipitation retrieval and data fusion/assimilation as inverse problems and using a regularized variational approach with the regularization term(s) selected to impose desired constraints on the solution, leads to improved representation of extremes. Here we present some new theoretical and computational developments which extend the ideas to a framework of retrieval via a regularized search within properly constructed data bases. We test the framework in several tropical storms over the Ganges-Brahmaputra delta region and over the Himalayas and compare the results with the standard retrieval algorithms currently used for operational purposes.

  20. Numerical Prediction of Cold Season Fog Events over Complex Terrain: the Performance of the WRF Model During MATERHORN-Fog and Early Evaluation

    NASA Astrophysics Data System (ADS)

    Pu, Zhaoxia; Chachere, Catherine N.; Hoch, Sebastian W.; Pardyjak, Eric; Gultepe, Ismail

    2016-08-01

    A field campaign to study cold season fog in complex terrain was conducted as a component of the Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) Program from 07 January to 01 February 2015 in Salt Lake City and Heber City, Utah, United States. To support the field campaign, an advanced research version of the Weather Research and Forecasting (WRF) model was used to produce real-time forecasts and model evaluation. This paper summarizes the model performance and preliminary evaluation of the model against the observations. Results indicate that accurately forecasting fog is challenging for the WRF model, which produces large errors in the near-surface variables, such as relative humidity, temperature, and wind fields in the model forecasts. Specifically, compared with observations, the WRF model overpredicted fog events with extended duration in Salt Lake City because it produced higher moisture, lower wind speeds, and colder temperatures near the surface. In contrast, the WRF model missed all fog events in Heber City, as it reproduced lower moisture, higher wind speeds, and warmer temperatures against observations at the near-surface level. The inability of the model to produce proper levels of near-surface atmospheric conditions under fog conditions reflects uncertainties in model physical parameterizations, such as the surface layer, boundary layer, and microphysical schemes.

  1. A Mesoscale Model-Based Climatography of Nocturnal Boundary-Layer Characteristics over the Complex Terrain of North-Western Utah

    NASA Astrophysics Data System (ADS)

    Serafin, Stefano; De Wekker, Stephan F. J.; Knievel, Jason C.

    2016-06-01

    Nocturnal boundary-layer phenomena in regions of complex topography are extremely diverse and respond to a multiplicity of forcing factors, acting primarily at the mesoscale and microscale. The interaction between different physical processes, e.g., drainage promoted by near-surface cooling and ambient flow over topography in a statically stable environment, may give rise to special flow patterns, uncommon over flat terrain. Here we present a climatography of boundary-layer flows, based on a 2-year archive of simulations from a high-resolution operational mesoscale weather modelling system, 4DWX. The geographical context is Dugway Proving Ground, in north-western Utah, USA, target area of the field campaigns of the MATERHORN (Mountain Terrain Atmospheric Modeling and Observations Program) project. The comparison between model fields and available observations in 2012-2014 shows that the 4DWX model system provides a realistic representation of wind speed and direction in the area, at least in an average sense. Regions displaying strong spatial gradients in the field variables, thought to be responsible for enhanced nocturnal mixing, are typically located in transition areas from mountain sidewalls to adjacent plains. A key dynamical process in this respect is the separation of dynamically accelerated downslope flows from the surface.

  2. Numerical Prediction of Cold Season Fog Events over Complex Terrain: the Performance of the WRF Model During MATERHORN-Fog and Early Evaluation

    NASA Astrophysics Data System (ADS)

    Pu, Zhaoxia; Chachere, Catherine N.; Hoch, Sebastian W.; Pardyjak, Eric; Gultepe, Ismail

    2016-09-01

    A field campaign to study cold season fog in complex terrain was conducted as a component of the Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) Program from 07 January to 01 February 2015 in Salt Lake City and Heber City, Utah, United States. To support the field campaign, an advanced research version of the Weather Research and Forecasting (WRF) model was used to produce real-time forecasts and model evaluation. This paper summarizes the model performance and preliminary evaluation of the model against the observations. Results indicate that accurately forecasting fog is challenging for the WRF model, which produces large errors in the near-surface variables, such as relative humidity, temperature, and wind fields in the model forecasts. Specifically, compared with observations, the WRF model overpredicted fog events with extended duration in Salt Lake City because it produced higher moisture, lower wind speeds, and colder temperatures near the surface. In contrast, the WRF model missed all fog events in Heber City, as it reproduced lower moisture, higher wind speeds, and warmer temperatures against observations at the near-surface level. The inability of the model to produce proper levels of near-surface atmospheric conditions under fog conditions reflects uncertainties in model physical parameterizations, such as the surface layer, boundary layer, and microphysical schemes.

  3. Evaluation of the TMPA-3B42 precipitation product using a high-density rain gauge network over complex terrain in northeastern Iberia

    NASA Astrophysics Data System (ADS)

    El Kenawy, Ahmed M.; Lopez-Moreno, Juan I.; McCabe, Matthew F.; Vicente-Serrano, Sergio M.

    2015-10-01

    The performance of the Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA)-3B42 version 7 product is assessed over north-eastern Iberia, a region with considerable topographical gradients and complexity. Precipitation characteristics from a dense network of 656 rain gauges, spanning the period from 1998 to 2009, are used to evaluate TMPA-3B42 estimates on a daily scale. A set of accuracy estimators, including the relative bias, mean absolute error (MAE), root mean square error (RMSE) and Spearman coefficient was used to evaluate the results. The assessment indicates that TMPA-3B42 product is capable of describing the seasonal characteristics of the observed precipitation over most of the study domain. In particular, TMPA-3B42 precipitation agrees well with in situ measurements, with MAE less than 2.5 mm.day- 1, RMSE of 6.4 mm.day- 1 and Spearman correlation coefficients generally above 0.6. TMPA-3B42 provides improved accuracies in winter and summer, whereas it performs much worse in spring and autumn. Spatially, the retrieval errors show a consistent trend, with a general overestimation in regions of low altitude and underestimation in regions of heterogeneous terrain. TMPA-3B42 generally performs well over inland areas, while showing less skill in the coastal regions. A set of skill metrics, including a false alarm ratio [FAR], frequency bias index [FBI], the probability of detection [POD] and threat score [TS], is also used to evaluate TMPA performance under different precipitation thresholds (1, 5, 10, 25 and 50 mm.day- 1). The results suggest that TMPA-3B42 retrievals perform well in specifying moderate rain events (5-25 mm.day- 1), but show noticeably less skill in producing both light (< 1 mm.day- 1) and heavy rainfall thresholds (more than 50 mm.day- 1). Given the complexity of the terrain and the associated high spatial variability of precipitation in north-eastern Iberia, the results reveal that TMPA-3B42 data provide

  4. Landfills in karst terrains

    SciTech Connect

    Hughes, T.H. ); Memon, B.A.; LaMoreaux, P.E. )

    1994-06-01

    State and Federal regulations have established restrictions for location of hazardous waste and municipal, solid waste landfills. Regulations require owners/operators to demonstrate that the hydrogeology has been completely characterized at proposed landfills, and that locations for monitoring wells have been properly selected. Owners/operators are also required to demonstrate that engineering measures have been incorporated in the design of the municipal solid waste landfills, so that the site is not subject to destabilizing events, as a result of location in unstable areas, such as karst terrains. Karst terrains are typically underlain by limestone or dolomite, and may contain a broad continuum of karst features and karst activity. Preliminary investigation of candidate sites will allow ranking of the sites, rejection of some unsuitable sites, and selection of a few sites for additional studies. The complexity of hydrogeologic systems, in karst terrains, mandates thorough hydrogeologic studies to determine whether a specific site is, or can be rendered, suitable for a land disposal facility. Important components of hydrogeologic studies are: field mapping of structural and stratigraphic units; interpretation of sequential aerial photographs; test drilling and geophysical analyses; fracture analyses; seasonal variation in water-levels; spatial variation of hydraulic characteristics of the aquifer and aquiclude; velocity and direction of movement of ground water within aquifers; determination of control for recharge, discharge, and local base level; and evaluation of the effects of man's activities, such as pumping, dewatering and construction.

  5. Large-eddy Simulation of Atmospheric Boundary-layer Flow through a Wind Farm Sited on Complex Terrain

    NASA Astrophysics Data System (ADS)

    Shamsoddin, Sina; Porté-Agel, Fernando

    2015-04-01

    In this work, the performance of a wind farm situated on a hilly terrain is studied using large-eddy simulation and especial attention is paid to the effect of the topography on the wake flow characteristics. To this end, first, boundary-layer flow is simulated over a two-dimensional hill and the corresponding mean and instantaneous flow-field is captured. Subsequently, flow simulation through a wind farm, consisting of five horizontal-axis wind turbines, sited over the same hill in an aligned layout is performed and the resulting flow characteristics are compared with the former case, i.e., the case without wind turbines. To assess the validity of the simulations, the calculated results are compared with the measurements carried out by Tian et al. (2013) in the aerodynamic/atmospheric boundary layer wind tunnel of Iowa State University. The agreement between the simulation and experimental results is good in terms of mean velocity and turbulence intensity profiles at different streamwise positions.

  6. Assessment of the ARW-WRF model over complex terrain: the case of the Stellenbosch Wine of Origin district of South Africa

    NASA Astrophysics Data System (ADS)

    Soltanzadeh, Iman; Bonnardot, Valérie; Sturman, Andrew; Quénol, Hervé; Zawar-Reza, Peyman

    2016-07-01

    Global warming has implications for thermal stress for grapevines during ripening, so that wine producers need to adapt their viticultural practices to ensure optimum physiological response to environmental conditions in order to maintain wine quality. The aim of this paper is to assess the ability of the Weather Research and Forecasting (WRF) model to accurately represent atmospheric processes at high resolution (500 m) during two events during the grapevine ripening period in the Stellenbosch Wine of Origin district of South Africa. Two case studies were selected to identify areas of potentially high daytime heat stress when grapevine photosynthesis and grape composition were expected to be affected. The results of high-resolution atmospheric model simulations were compared to observations obtained from an automatic weather station (AWS) network in the vineyard region. Statistical analysis was performed to assess the ability of the WRF model to reproduce spatial and temporal variations of meteorological parameters at 500-m resolution. The model represented the spatial and temporal variation of meteorological variables very well, with an average model air temperature bias of 0.1 °C, while that for relative humidity was -5.0 % and that for wind speed 0.6 m s-1. Variation in model performance varied between AWS and with time of day, as WRF was not always able to accurately represent effects of nocturnal cooling within the complex terrain. Variations in performance between the two case studies resulted from effects of atmospheric boundary layer processes in complex terrain under the influence of the different synoptic conditions prevailing during the two periods.

  7. Coupling fast all-season soil strength land surface model with weather research and forecasting model to assess low-level icing in complex terrain

    NASA Astrophysics Data System (ADS)

    Sines, Taleena R.

    Icing poses as a severe hazard to aircraft safety with financial resources and even human lives hanging in the balance when the decision to ground a flight must be made. When analyzing the effects of ice on aviation, a chief cause for danger is the disruption of smooth airflow, which increases the drag force on the aircraft therefore decreasing its ability to create lift. The Weather Research and Forecast (WRF) model Advanced Research WRF (WRF-ARW) is a collaboratively created, flexible model designed to run on distributed computing systems for a variety of applications including forecasting research, parameterization research, and real-time numerical weather prediction. Land-surface models, one of the physics options available in the WRF-ARW, output surface heat and moisture flux given radiation, precipitation, and surface properties such as soil type. The Fast All-Season Soil STrength (FASST) land-surface model was developed by the U.S. Army ERDC-CRREL in Hanover, New Hampshire. Designed to use both meteorological and terrain data, the model calculates heat and moisture within the surface layer as well as the exchange of these parameters between the soil, surface elements (such as snow and vegetation), and atmosphere. Focusing on the Presidential Mountain Range of New Hampshire under the NASA Experimental Program to Stimulate Competitive Research (EPSCoR) Icing Assessments in Cold and Alpine Environments project, one of the main goals is to create a customized, high resolution model to predict and assess ice accretion in complex terrain. The purpose of this research is to couple the FASST land-surface model with the WRF to improve icing forecasts in complex terrain. Coupling FASST with the WRF-ARW may improve icing forecasts because of its sophisticated approach to handling processes such as meltwater, freezing, thawing, and others that would affect the water and energy budget and in turn affect icing forecasts. Several transformations had to take place in order

  8. Validation of high-resolution WRF-ARW model runs against airborne measurements over complex terrain in central Italy

    NASA Astrophysics Data System (ADS)

    Carotenuto, Federico; Gioli, Beniamino; Toscano, Piero; Gualtieri, Giovanni; Miglietta, Franco; Wohlfahrt, Georg

    2015-04-01

    An intensive aerial campaign was flown in the context of the CARBIUS project (Maselli et al., 2010) between July 2004 and December 2005. The flights covered, over more than 240 Km, a target area in central Italy (between the regions of Lazio and Tuscany) characterized by various land uses and topography, ranging from coastal zones to mountainous landscapes (Colline Metallifere, Tuscany). The aerial vector (Sky Arrow 650 ERA) was equipped for high frequency (50 Hz) measurements of the three components of mean wind and turbulence, as well as air temperature, CO2 and H2O concentrations. While the aim of the CARBIUS campaign was focused on GHG fluxes, the dataset is used in the present work as a benchmark to assess the capability of mesoscale models to correctly simulate transport fields. A first assessment has been done by comparing the dataset to a coupled WRF-NMM-CALMET system (Gioli et al., 2014), but the aim of the present work is to expand on those foundations by comparing the data to higher resolution WRF-ARW simulations. WRF-ARW outputs are, in fact, frequently used as inputs to multiple dispersion models and any misrepresentation of the "real" situation is therefore propagated through the modelling chain. Our aim is to assess these potential errors keeping into account different topographic situations and seasons thanks to the existent aerial dataset. Moreover the sensitivity of the WRF-ARW model to different initial and boundary conditions (ECMWF vs. CFSR) is explored, since also the initial forcing may influence the representation of the transport field. Results show that the model is generally capable of reproducing the main features of the mean wind field independently from the choice of the initial forcing. Terrain features still show an impact on the model outputs (especially on wind directions), moreover the performance of the model is also influenced by seasonal effects. Gioli B., Gualtieri G., Busillo C., Calastrini F., Gozzini B., Miglietta F. (2014

  9. Evaluating Wind Fields from a Diagnostic Model Over Complex Terrain in the Phoenix Region and Implications to Dispersion Calculations for Regional Emergency Response

    SciTech Connect

    Wang, Weiguo; Shaw, William J.

    2009-12-01

    This paper compares the wind field from a diagnostic model (CALMET) over complex terrain in the Phoenix region in the USA with observations that are gridded by a state-of-the-art Four-Dimensional Data Assimilation (FDDA) system. The wind difference between the CALMET and FDDA wind fields is larger at night than in the day. The magnitude of the wind difference can be smaller than 5% of the mean wind speed at low levels in areas with dense observational stations, while it can be larger than 80% in areas without observational stations or at high altitudes. The vector-mean wind direction difference over the domain is 15 deg on the surface level and 25 deg between 10 and 1500 m. To evaluate the effects of the wind difference on dispersion calculations, dispersion of a hypothetical passive tracer released from surface point sources is simulated by the second-order closure integrated puff (SCIPUFF) model driven by the CALMET and FDDA wind fields, respectively. Differences in the two simulated tracer concentration fields increase with time due to accumulation of effects of the wind differences both near the surface and at higher altitudes. Even for the release in the area with the densest distribution of surface stations, the relative difference in the peak surface concentration from CALMET-SCIPUFF and from FDDA-SCIPUFF is less than 10% only within 0.5 hr after the release in the afternoon, and increases to 70% at 1.5 hr; this is because of large differences in wind above the surface. For the release in the area with few stations, the difference can be larger than 100% or even larger after 1.5 hr from the release. To improve dispersion simulations driven by the CALMET wind in the region, observations at upper-air stations are needed and the current surface observation network needs to be reorganized or more stations are needed to account for the influence of terrain.

  10. A multiscale modelling methodology applicable for regulatory purposes taking into account effects of complex terrain and buildings on pollutant dispersion: a case study for an inner Alpine basin.

    PubMed

    Oettl, D

    2015-11-01

    Dispersion modelling in complex terrain always has been challenging for modellers. Although a large number of publications are dedicated to that field, candidate methods and models for usage in regulatory applications are scarce. This is all the more true when the combined effect of topography and obstacles on pollutant dispersion has to be taken into account. In Austria, largely situated in Alpine regions, such complex situations are quite frequent. This work deals with an approach, which is in principle capable of considering both buildings and topography in simulations by combining state-of-the-art wind field models at the micro- (<1 km) and mesoscale γ (2-20 km) with a Lagrangian particle model. In order to make such complex numerical models applicable for regulatory purposes, meteorological input data for the models need to be readily derived from routine observations. Here, use was made of the traditional way to bin meteorological data based on wind direction, speed, and stability class, formerly mainly used in conjunction with Gaussian-type models. It is demonstrated that this approach leads to reasonable agreements (fractional bias < 0.1) between observed and modelled annual average concentrations in an Alpine basin with frequent low-wind-speed conditions, temperature inversions, and quite complex flow patterns, while keeping the simulation times within the frame of possibility with regard to applications in licencing procedures. However, due to the simplifications in the derivation of meteorological input data as well as several ad hoc assumptions regarding the boundary conditions of the mesoscale wind field model, the methodology is not suited for computing detailed time and space variations of pollutant concentrations. PMID:26162440

  11. A multiscale modelling methodology applicable for regulatory purposes taking into account effects of complex terrain and buildings on pollutant dispersion: a case study for an inner Alpine basin.

    PubMed

    Oettl, D

    2015-11-01

    Dispersion modelling in complex terrain always has been challenging for modellers. Although a large number of publications are dedicated to that field, candidate methods and models for usage in regulatory applications are scarce. This is all the more true when the combined effect of topography and obstacles on pollutant dispersion has to be taken into account. In Austria, largely situated in Alpine regions, such complex situations are quite frequent. This work deals with an approach, which is in principle capable of considering both buildings and topography in simulations by combining state-of-the-art wind field models at the micro- (<1 km) and mesoscale γ (2-20 km) with a Lagrangian particle model. In order to make such complex numerical models applicable for regulatory purposes, meteorological input data for the models need to be readily derived from routine observations. Here, use was made of the traditional way to bin meteorological data based on wind direction, speed, and stability class, formerly mainly used in conjunction with Gaussian-type models. It is demonstrated that this approach leads to reasonable agreements (fractional bias < 0.1) between observed and modelled annual average concentrations in an Alpine basin with frequent low-wind-speed conditions, temperature inversions, and quite complex flow patterns, while keeping the simulation times within the frame of possibility with regard to applications in licencing procedures. However, due to the simplifications in the derivation of meteorological input data as well as several ad hoc assumptions regarding the boundary conditions of the mesoscale wind field model, the methodology is not suited for computing detailed time and space variations of pollutant concentrations.

  12. Digital terrain tapes: user guide

    USGS Publications Warehouse

    ,

    1980-01-01

    DMATC's digital terrain tapes are a by-product of the agency's efforts to streamline the production of raised-relief maps. In the early 1960's DMATC developed the Digital Graphics Recorder (DGR) system that introduced new digitizing techniques and processing methods into the field of three-dimensional mapping. The DGR system consisted of an automatic digitizing table and a computer system that recorded a grid of terrain elevations from traces of the contour lines on standard topographic maps. A sequence of computer accuracy checks was performed and then the elevations of grid points not intersected by contour lines were interpolated. The DGR system produced computer magnetic tapes which controlled the carving of plaster forms used to mold raised-relief maps. It was realized almost immediately that this relatively simple tool for carving plaster molds had enormous potential for storing, manipulating, and selectively displaying (either graphically or numerically) a vast number of terrain elevations. As the demand for the digital terrain tapes increased, DMATC began developing increasingly advanced digitizing systems and now operates the Digital Topographic Data Collection System (DTDCS). With DTDCS, two types of data elevations as contour lines and points, and stream and ridge lines are sorted, matched, and resorted to obtain a grid of elevation values for every 0.01 inch on each map (approximately 200 feet on the ground). Undefined points on the grid are found by either linear or or planar interpolation.

  13. Merging GOES-R ABI and TRMM/GPM Observations with MRMS Ground-Based Radar for Real-Time QPE in Complex Terrain

    NASA Astrophysics Data System (ADS)

    Grams, H.; Gourley, J. J.; Rabin, R.; Kirstetter, P.

    2014-12-01

    Real-time detection and estimation of rainfall at the flash flood scale remains a significant challenge in the Western United States where complex terrain limits NEXRAD coverage and rain gauge networks are sparse. Quantitative precipitation estimates (QPE) from geostationary satellites offer the advantage of full coverage and spatiotemporal resolution comparable to ground-based radars, particularly with the upcoming launch of GOES-R. A multisensor (NEXRAD+GPM+GOES-R) QPE product is under development that will capitalize on the complementary scales of NEXRAD and GOES-R measurements to provide high-resolution rainfall estimates in areas within and just outside the United States where ground radar coverage is not sufficient for flash flood detection and monitoring. As a first step, a multi-year database was developed over the continental United States of Multi-Radar/Multi-Sensor (MRMS) NEXRAD mosaics of surface precipitation types, rainfall rates, vertical profiles of reflectivity (VPRs), and the radar quality index (RQI), TRMM PR VPRs from 2A25 Version 7, and derived cloud properties from the GOES-R ABI proxy dataset. A Bayesian approach was then employed to match the cloud top observations to probability distributions of MRMS Q3 surface rain rates, using VPRs and precipitation types derived from MRMS as constraints. A description of the prototype QPE product and initial results will be presented.

  14. Evaluation of WRF-Predicted Near-Hub-Height Winds and Ramp Events over a Pacific Northwest Site with Complex Terrain

    SciTech Connect

    Yang, Qing; Berg, Larry K.; Pekour, Mikhail; Fast, Jerome D.; Newsom, Rob K.; Stoelinga, Mark; Finley, Catherine

    2013-08-01

    The WRF model version 3.3 is used to simulate near hub-height winds and power ramps utilizing three commonly used planetary boundary-layer (PBL) schemes: Mellor-Yamada-Janjic (MYJ), University of Washington (UW), and Yonsei University (YSU). The predicted winds have small mean biases compared with observations. Power ramps and step changes (changes within an hour) consistently show that the UW scheme performed better in predicting up ramps under stable conditions with higher prediction accuracy and capture rates. Both YSU and UW scheme show good performance predicting up- and down- ramps under unstable conditions with YSU being slightly better for ramp durations longer than an hour. MYJ is the most successful simulating down-ramps under stable conditions. The high wind speed and large shear associated with low-level jets are frequently associated with power ramps, and the biases in predicted low-level jet explain some of the shown differences in ramp predictions among different PBL schemes. Low-level jets were observed as low as ~200 m in altitude over the Columbia Basin Wind Energy Study (CBWES) site, located in an area of complex terrain. The shear, low-level peak wind speeds, as well as the height of maximum wind speed are not well predicted. Model simulations with 3 PBL schemes show the largest variability among them under stable conditions.

  15. Semi-automatic methods for landslide features and channel network extraction in a complex mountainous terrain: new opportunities but also challenges from high resolution topography

    NASA Astrophysics Data System (ADS)

    Tarolli, Paolo; Sofia, Giulia; Pirotti, Francesco; Dalla Fontana, Giancarlo

    2010-05-01

    In recent years, remotely sensed technologies such as airborne and terrestrial laser scanner have improved the detail of analysis providing high-resolution and high-quality topographic data over large areas better than other technologies. A new generation of high resolution (~ 1m) Digital Terrain Models (DTMs) are now available for different landscapes. These data call for the development of the new generation of methodologies for objective extraction of geomorphic features, such as channel heads, channel networks, bank geometry, landslide scars, service roads, etc. The most important benefit of a high resolution DTM is the detailed recognition of surface features. It is possible to recognize in detail divergent-convex landforms, associated with the dominance of hillslope processes, and convergent-concave landforms, associated with fluvial-dominated erosion. In this work, we test the performance of new methodologies for objective extraction of geomorphic features related to landsliding and channelized processes in order to provide a semi-automatic method for channel network and landslide features recognition in a complex mountainous terrain. The methodologies are based on the detection of thresholds derived by statistical analysis of variability of surface curvature. We considered a study area located in the eastern Italian Alps where a high-quality set of LiDAR data is available and where channel heads, related channel network, and landslides have been mapped in the field by DGPS. In the analysis we derived 1 m DTMs from bare ground LiDAR points, and we used different smoothing factors for the curvature calculation in order to set the more suitable curvature maps for the recognition of selected features. Our analyses suggest that: i) the scale for curvature calculations has to be a function of the scale of the features to be detected, (ii) rougher curvature maps are not optimal as they do not explore a sufficient range at which features occur, while smoother

  16. A GIS-based numerical model for simulating the kinematics of mud and debris flows over complex terrain

    NASA Astrophysics Data System (ADS)

    Beguería, S.; van Asch, Th. W. J.; Malet, J.-P.; Gröndahl, S.

    2009-11-01

    This article presents MassMov2D, a two-dimensional model of mud and debris flow dynamics over complex topography, based on a numerical integration of the depth-averaged motion equations using a shallow water approximation. The core part of the model was implemented using the GIS scripting language PCRaster. This environment provides visualization of the results through map animations and time series, and a user-friendly interface. The constitutive equations and the numerical solution adopted in MassMov2D are presented in this article. The model was applied to two field case studies of mud flows on torrential alluvial fans, one in the Austrian Tyrol (Wartschenbach torrent) and the other in the French Alps (Faucon torrent). Existing data on the debris flow volume, input discharge and deposits were used to back-analyze those events and estimate the values of the leading parameters. The results were compared with modeling codes used by other authors for the same case studies. The results obtained with MassMov2D matched well with the observed debris flow deposits, and are in agreement with those obtained using alternative codes.

  17. Smoke Dispersion Modeling Over Complex Terrain Using High-Resolution Meteorological Data and Satellite Observations: The FireHub Platform

    NASA Technical Reports Server (NTRS)

    Solomos, S.; Amiridis, V.; Zanis, P.; Gerasopoulos, E.; Sofiou, F. I.; Herekakis, T.; Brioude, J.; Stohl, A.; Kahn, R. A.; Kontoes, C.

    2015-01-01

    A total number of 20,212 fire hot spots were recorded by the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite instrument over Greece during the period 2002e2013. The Fire Radiative Power (FRP) of these events ranged from 10 up to 6000 MW at 1 km resolution, and many of these fire episodes resulted in long-range transport of smoke over distances up to several hundred kilometers. Three different smoke episodes over Greece are analyzed here using real time hot-spot observations from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) satellite instrument as well as from MODIS hot-spots. Simulations of smoke dispersion are performed with the FLEXPART-WRF model and particulate matter emissions are calculated directly from the observed FRP. The modeled smoke plumes are compared with smoke stereo-heights from the Multiangle Imaging Spectroradiometer (MISR) instrument and the sensitivities to atmospheric and modeling parameters are examined. Driving the simulations with high resolution meteorology (4 4 km) and using geostationary satellite data to identify the hot spots allows the description of local scale features that govern smoke dispersion. The long-range transport of smoke is found to be favored over the complex coastline environment of Greece due to the abrupt changes between land and marine planetary boundary layers (PBL) and the decoupling of smoke layers from the surface.

  18. The strength of contributions from topography mismatch and measurement filtering to simulated net ecosystem exchange in complex terrain

    NASA Astrophysics Data System (ADS)

    Brooks, B.; Desai, A. R.; Stephens, B. B.; Jacobson, A. R.

    2011-12-01

    Global scale carbon cycle inverse models provide invaluable information for the construction of empirically based carbon budgets based on in situ measurements. In landscapes of predominantly smooth topography inverse carbon cycle models are useful for diagnosing the magnitude and climate sensitivity of different regional carbon sinks. However, in landscapes of predominately complex topography inversion model results come with strong caveats for two reasons: 1) Coarse gridding of model topography can lead the model to sample observations at elevations far above the model surface, and 2) Transport wind fields over smoothed model representations of mountain regions are not always sufficiently resolved to inform the model about the source region for assimilated measurements. The uncertainty contributed by incorrect winds and topography mismatches (e.g., differences between the actual measurement elevation and model surface on the order of 1,000 m) is thought to be smaller for higher resolution regional inversion models (e.g., Gockede et al., 2010; Schuh et al. 2010), but these uncertainties are not well constrained for larger scale inversion systems (e.g., Peters et al., 2010), which are one of few ways for determining the relative priority of regional sinks. In this work we examine the effects on net ecosystem exchange (NEE) for a global scale inversion system when 1) topography mismatches are ameliorated, and 2) subset observations consistent with model resolution are used rather than observation-based subsets. Our focus is to use an example inversion model system, CarbonTracker (Peters et al., 2007; 2010), driven by CO2 mixing ratio measurements, including the RACCOON Network in the United States Mountain West (raccoon.ucar.edu), to quantify and compare the contribution to NEE from tower elevation mismatches and filtering strategies across biomes and and in terms of forecast skill (model data mismatch). We further compare our results to the differences in NEE over

  19. Automatic remote sensing detection of the convective boundary layer structure over flat and complex terrain using the novel PathfinderTURB algorithm

    NASA Astrophysics Data System (ADS)

    Poltera, Yann; Martucci, Giovanni; Hervo, Maxime; Haefele, Alexander; Emmenegger, Lukas; Brunner, Dominik; Henne, stephan

    2016-04-01

    We have developed, applied and validated a novel algorithm called PathfinderTURB for the automatic and real-time detection of the vertical structure of the planetary boundary layer. The algorithm has been applied to a year of data measured by the automatic LIDAR CHM15K at two sites in Switzerland: the rural site of Payerne (MeteoSwiss station, 491 m, asl), and the alpine site of Kleine Scheidegg (KSE, 2061 m, asl). PathfinderTURB is a gradient-based layer detection algorithm, which in addition makes use of the atmospheric variability to detect the turbulent transition zone that separates two low-turbulence regions, one characterized by homogeneous mixing (convective layer) and one above characterized by free tropospheric conditions. The PathfinderTURB retrieval of the vertical structure of the Local (5-10 km, horizontal scale) Convective Boundary Layer (LCBL) has been validated at Payerne using two established reference methods. The first reference consists of four independent human-expert manual detections of the LCBL height over the year 2014. The second reference consists of the values of LCBL height calculated using the bulk Richardson number method based on co-located radio sounding data for the same year 2014. Based on the excellent agreement with the two reference methods at Payerne, we decided to apply PathfinderTURB to the complex-terrain conditions at KSE during 2014. The LCBL height retrievals are obtained by tilting the CHM15K at an angle of 19 degrees with respect to the horizontal and aiming directly at the Sphinx Observatory (3580 m, asl) on the Jungfraujoch. This setup of the CHM15K and the processing of the data done by the PathfinderTURB allows to disentangle the long-transport from the local origin of gases and particles measured by the in-situ instrumentation at the Sphinx Observatory. The KSE measurements showed that the relation amongst the LCBL height, the aerosol layers above the LCBL top and the gas + particle concentration is all but

  20. MODIS Land Surface Temperature time series reconstruction with Open Source GIS: A new quality of temperature based ecological indicators in complex terrain (Invited)

    NASA Astrophysics Data System (ADS)

    Neteler, M.

    2009-12-01

    In complex terrain like the Central European Alps, meteorological stations and ground surveys are usually sparsely and/or irregularly distributed and often favor agricultural areas. The application of traditional geospatial interpolation methods in complex terrain remains challenging and difficult to optimize. An alternative data source is remote sensing: high temporal resolution satellite data are continuously gaining interest since these data are intrinsically spatialized: continuous field of observations is obtained with this tool instead of point data. The increasing data availability suggests using these time series as surrogate to certain measures from meteorological stations, especially for temperature and related derivatives. The Terra and Aqua satellites with the Moderate Resolution Imaging Spectroradiometer (MODIS) provide four Earth coverages per day at various resolutions. We analyzed 8 years (2000 to 2008) of daily land surface temperature (LST) data from MODIS in an area located in the Southern European Alps. A method was developed to reconstruct incomplete maps (cloud coverage, invalid pixels) based on image statistics and on a model that includes additional GIS layers. The original LST map resolution of 1000m could be improved to 200m in this process which renders the resulting LST maps applicable at regional scales. We propose the use of these reconstructed daily LST time series as surrogate to meteorological observations especially in the area of epidemiological modeling where data are typically aggregated to decadal indicators. From these daily LST map series, derivable indicators include: 1) temperatures minima, means and maxima for annual/monthly/decadal periods; 2) unusual hot summers;3) the calculation of growing degree days, and 4) spring temperature increase or autumnal temperature decrease. Since more than 8 years of MODIS LST data are available today, even preliminary gradients can be extracted to assess multi-annual temperature trends

  1. Statutory complexity disguises agency capture in Citizens Coal Council v. EPA

    SciTech Connect

    Mullen, R.

    2007-07-01

    In Citizens Coal Council v. EPA, an en banc panel for the Sixth Circuit Court of Appeals considered a challenge to EPA regulations promulgated pursuant to the Clean Water Act (CWA). The EPA promulgated the regulations in an attempt to incentivize coal companies to remine once abandoned mine sites. Petitioners, two nonprofit environmental organizations, claimed that the regulations violated the Clean Water Act and Administrative Procedure Act by allowing coal companies to remine without adhering to any enforceable pollution limitations. The EPA countered that more remining would improve water quality at abandoned sites. The Sixth Circuit rejected Petitioners' claims, finding that the EPA's regulations were reasonably consistent with the CWA's goal of restoring the integrity of the nation's waters. In so holding, the court struggled to understand the meaning of the CWA's complex procedural and technical language, and allowed the EPA to justify the rule based on the CWA's broad statement of purpose. Such superficial judicial review sets a dangerous precedent in environmental law, because it exacerbates the risk of agency capture. A captured agency promulgates regulations that benefit-industry, not the environment. Without the judiciary acting as a meaningful check against agency capture, the public loses a valuable tool in the fight against major-industrial polluters like the domestic coal industry. Citizens Coal Council therefore stands as a cautionary tale, a warning sign that the judiciary may be unable to identify agency capture where the regulations at issue are promulgated pursuant to a complex statute like the Clean Water Act.

  2. Categorization of nocturnal drainage flows within the Brush Creek valley in western Colorado and the variability of sigma theta in complex terrain

    SciTech Connect

    Gudiksen, P.H.

    1985-03-01

    The monthly frequencies of nocturnal drainage flows in the Brush Creek valley were estimated over the period August 1982 to January 1985 for the purpose of evaluating the representativeness of the drainage flows observed during a few intensive study periods. These estimates were made on the basis of data from three short meteorological towers situated in the valley. The highest frequencies were observed during the June to October timeframes: 30 to 40% during 1983 and 10 to 30% during 1984. Of the ten experimental nights when intensive investigations were conducted within the Brush Creek valley, seven were during strong drainage flow periods and three were during weaker drainage flow periods. The variability of sigma theta in complex terrain areas was investigated since this parameter is often used to estimate diffusion of pollutants. Measurements made during strong drainage flow periods within two valleys in The Geysers geothermal area in northern California and within the Brush Creek valley yielded hourly-averaged values that varied from a few degrees to a little over one hundred degrees at each measurement site. The median values typically ranged from 15{sup 0} to 40{sup 0}. Generally, the highest values were acquired at measurement sites situated on the valley floor; the lowest values on the ridges; and intermediate values along the slopes. This ordering may be due to the winds generally being stronger over the ridges than within the valley, since there is weak evidence for an inverse relationship between the median wind speeds and sigma theta values, even though this relationship was not in evidence between the individual measurements. 3 refs., 9 figs., 2 tabs.

  3. Simulation of atmospheric dispersion of NOX over complex terrain region of Ranchi with FLEXPART-WRF by incorporation of improved turbulence intensity relationships

    NASA Astrophysics Data System (ADS)

    Madala, Srikanth; Satyanarayana, A. N. V.; Srinivas, C. V.

    2015-12-01

    Accurate representation of air pollutant dispersion is essential for environmental management and planning purposes. In this study, semi-empirical relationships of turbulence intensity (σu/u*, σv/u* and σw/u*) as a function of surface layer scaling and local stability are developed following boundary layer similarity concepts at Ranchi, a complex terrain in Jharkhand, Eastern India for various seasons. The impact of the new turbulence parameterization for air pollution dispersion simulation is studied by incorporating the same in the Hanna scheme of FLEXPART-WRF Lagrangian Particle dispersion model over study region. The model is used to estimate the ground level concentrations of nitrogen oxides (NOx) due to industrial and vehicular sources in study region. The meteorological parameters needed in air-quality simulation are simulated using the Advanced Research WRF (ARW) mesoscale model at high resolution (3 km). Three turbulence schemes (YSU, MYNN2 and ACM2) in ARW are alternatively tested in dispersion simulation and comparisons are made with available air quality data for eight days in different seasons (winter, pre-monsoon, monsoon and post-monsoon). Simulations with FLEXPART revealed distinct seasonal variation of dispersion patterns. It has been found that the new turbulence intensity relationships in FLEXPART improved the NOx concentration estimates by reducing the negative bias seen with default Hanna scheme. Further, the ARW simulated meteorological parameters using ACM2 and MYNN2 significantly reduced the bias in modeled pollutant concentrations. The study demonstrates the utility of high quality seasonal turbulence measurements in pollution dispersion model for better diffusion parameterization needed in air quality modeling.

  4. Conceptualizing the regional hydrology of a complex low relief terrain: Climate - geology interactions on sink-source dynamics of Western Boreal forests

    NASA Astrophysics Data System (ADS)

    Devito, K. J.; Mendoza, C. A.; Petrone, R. M.; Landhäusser, S.; Silins, U.; Qualizza, C.; Gignac, D.

    2011-12-01

    The Western Boreal Plain (WBP) eco-region of western Canada is experiencing unprecedented industrial development for forest, oil and gas resources, stressing the need to assess and understand the sink and source areas of regional water flow. This requires the development of models that can be use to predict and mitigate the impacts of land use changes on water quantity and quality. The WBP is characterized by low relief, hummocky terrain with complexes of forestland and wetlands, especially peatlands. A paired aspen forest harvest experiment (HEAD2) was conducted on adjacent pond-peatland-aspen forestland complexes of a moraine landform, ubiquitous throughout the WBP, to determine the influence of aspen vegetated forestlands and harvesting relative to wetlands on local and regional water cycling. Reductions in transpiration and interception following aspen harvest resulted in some increase in soil moisture. However, excess water was largely absorbed into deep moraine substrates and resulted in groundwater recharge with little or no lateral flow to adjacent wetlands and aquatic systems. As a result of high soil and groundwater storage there was no observable difference in runoff from the harvested catchment compared to the adjacent reference (uncut) catchment confirming that in most years runoff originates from the wetland (peatland) rather than forestland hydrologic units. Furthermore, soil moisture increases were short lived due to rapid redevelopment of leaf area as result of high-density regeneration of aspen through root suckering. Recovery of transpiration and interception to near pre-harvest conditions occurred within 3 years. Climate cycles, primarily inter-annual variation in snow pack, can overwhelm the influence of aspen harvest in the WBP, as during the harvest experiment large water table rises were observed in both the uncut and the harvested forestlands. This study illustrates that forestlands on deep moraine hummocky substrates of the WBP act

  5. 77 FR 51731 - All-Terrain Vehicle Safety Summit

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-27

    ... COMMISSION 16 CFR Chapter II All-Terrain Vehicle Safety Summit AGENCY: Consumer Product Safety Commission... announcing its intent to hold a Summit on all-terrain vehicle (ATV) safety. The Summit will be held at the... information at the Summit should register by September 14, 2012; all other individuals who wish to attend...

  6. In search of the mechanisms behind soil carbon metabolism of a Douglas fir forest in complex terrain using naturally abundant 13C

    NASA Astrophysics Data System (ADS)

    Kayler, Z. E.; Sulzman, E. W.; Barnard, H. R.; Kennedy, A.; Phillips, C.; Mix, A.; Bond, B. J.

    2008-12-01

    Soil is well known for being highly variable, spatially and temporally, in moisture, texture, nutrients, carbon content and organisms. The magnitude of variation in soil characteristics represented in a study is, in part, determined by the choice in site location. Choosing sites that are topographically flat reduces variability due to environmental gradients, variability that is amplified in sites of complex terrain. We measured soil respiration, an integrative measure of ecosystem biological and physical processes, and its isotopic signature (δ13CR-s) to accomplish two goals: 1. Explore how gradients in temperature and moisture within a steeply sloped watershed affect the flux and isotopic signature of soil CO2 2. Deconvolve the isotopic signature of soil respiration into autotrophic and heterotrophic sources using a multi-source mixing model constrained by samples of soil organic matter and water soluble extracts of leaf foliage. Our site is located in a steep catchment within the central Cascades of Oregon (HJ Andrews LTER) where we made respiration measurements in plots established along side a sensor transect that continuously measures soil moisture and temperature; air relative humidity and temperature; and tree transpiration. There was a distinct difference in soil metabolism between the south and north aspects in the watershed. Temperature-corrected basal respiration of the south facing slope was 1 μmol m-2s-1 greater than the north facing slope. There was also a difference in isotopic signature between the two slopes that could be as great as 2 per mil depending on the period within the growing season. The strength of the correlation between environmental variables and soil carbon flux was non-uniform across the catchment. There was, however, a strong positive correlation between soil flux with recent transpiration rates (0 to 3 days prior) as well as with transpiration rates that occurred up to 9 days previously. This pattern was especially prevalent

  7. Complex terrain in the Critical Zone: How topography drives ecohydrological patterns of soil and plant carbon exchange in a semiarid mountainous system

    NASA Astrophysics Data System (ADS)

    Barron-Gafford, G.; Minor, R. L.; Heard, M. M.; Sutter, L. F.; Yang, J.; Potts, D. L.

    2015-12-01

    The southwestern U.S. is predicted to experience increasing temperatures and longer periods of inter-storm drought. High temperature and water deficit restrict plant productivity and ecosystem functioning, but the influence of future climate is predicted to be highly heterogeneous because of the complex terrain characteristic of much of the Critical Zone (CZ). Within our Critical Zone Observatory (CZO) in the Southwestern US, we monitor ecosystem-scale carbon and water fluxes using eddy covariance. This whole-ecosystem metric is a powerful integrating measure of ecosystem function over time, but details on spatial heterogeneity resulting from topographic features of the landscape are not captured, nor are interactions among below- and aboveground processes. We supplement eddy covariance monitoring with distributed measures of carbon flux from soil and vegetation across different aspects to quantify the causes and consequences of spatial heterogeneity through time. Given that (i) aspect influences how incoming energy drives evaporative water loss and (ii) seasonality drives temporal patterns of soil moisture recharge, we were able to examine the influence of these processes on CO2 efflux by investigating variation across aspect. We found that aspect was a significant source of spatial heterogeneity in soil CO2 efflux, but the influence varied across seasonal periods. Snow on South-facing aspects melted earlier and yielded higher efflux rates in the spring. However, during summer, North- and South-facing aspects had similar amounts of soil moisture, but soil temperatures were warmer on the North-facing aspect, yielding greater rates of CO2 efflux. Interestingly, aspect did not influence photosynthetic rates. Taken together, we found that physical features of the landscape yielded predictable patterns of levels and phenologies of soil moisture and temperature, but these drivers differentially influenced below- and aboveground sources of carbon exchange. Conducting

  8. Terrain-Responsive Atmospheric Code

    1991-11-20

    The Terrain-Responsive Atmospheric Code (TRAC) is a real-time emergency response modeling capability designed to advise Emergency Managers of the path, timing, and projected impacts from an atmospheric release. TRAC evaluates the effects of both radiological and non-radiological hazardous substances, gases and particulates. Using available surface and upper air meteorological information, TRAC realistically treats complex sources and atmospheric conditions, such as those found in mountainous terrain. TRAC calculates atmospheric concentration, deposition, and dose for more thanmore » 25,000 receptor locations within 80 km of the release point. Human-engineered output products support critical decisions on the type, location, and timing of protective actions for workers and the public during an emergency.« less

  9. 75 FR 5767 - All Terrain Vehicle Chinese Language Webinar; Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-04

    ... From the Federal Register Online via the Government Publishing Office CONSUMER PRODUCT SAFETY COMMISSION All Terrain Vehicle Chinese Language Webinar; Meeting AGENCY: Consumer Product Safety Commission. ACTION: Notice. The Consumer Product Safety Commission (CPSC) is announcing the following meeting:...

  10. LOLA: Defining Lunar Terrain

    NASA Video Gallery

    The Lunar Orbiter Laser Altimeter (LOLA) instrument on board NASA's LRO spacecraft builds the highest detail topography currently available of the lunar terrain. In this video David Smith, LOLA's P...

  11. ARAC terrain data base

    SciTech Connect

    Walker, H.

    1982-11-01

    A terrain data base covering the continental United States at 500-meter resolution has been generated. Its function is to provide terrain data for input to mesoscale atmospheric models that are used as part of the Atmospheric Release Advisory Capability at Lawrence Livermore Laboratory (LLNL). The structure of the data base as it exists on the LLNL computer system is described. The data base has been written to tapes for transfer to other systems and the format of these tapes is also described.

  12. Evaluation of a spatial rainfall generator and an interpolation methods for the creation of future gridded data sets over complex terrains

    NASA Astrophysics Data System (ADS)

    Camera, Corrado; Bruggeman, Adriana; Hadjinicolaou, Panos; Michaelides, Silas; Lange, Manfred A.

    2015-04-01

    Space-time variability of precipitation plays a key role as a driver of many processes in different environmental fields like hydrology, ecology, biology, agriculture, and natural hazards. The objective of this study was to compare two approaches for statistical downscaling of precipitation from climate models. The study was applied to the island of Cyprus, an orographically complex terrain. The first approach makes use of a spatial temporal Neyman-Scott Rectangular Pulses (NSRP) model and a previously tested interpolation scheme (Camera et al., 2014). The second approach is based on the use of the single site NSRP model and a simplified gridded scheme based on scaling coefficients obtained from past observations. The rainfall generators were evaluated on the period 1980-2010. Both approaches were subsequently used to downscale three RCMs from the EU ENSEMBLE project to calculate climate projections (2020-2050). The main advantage of the spatial-temporal approach is that it allows creating spatially consistent daily maps of precipitation. On the other hand, due to the assumptions made using a stochastic generator based on homogeneous Poisson processes, it shows a smoothing out of all the rainfall statistics (except mean and variance) all over the study area. This leads to high errors when analyzing indices related to extremes. Examples are the number of days with rainfall over 50 mm (R50 - mean error 65%), the 95th percentile value of rainy days (RT95 - mean error 19%), and the mean annual rainfall recorded on days with rainfall above the 95th percentile (RA95 - mean error 22%). The single site approach excludes the possibility of using the created gridded data sets for case studies involving spatial connection between grid cells (e.g. hydrologic modelling), but it leads to a better reproduction of rainfall statistics and properties. The errors for the extreme indices are in fact much lower: 17% for R50, 4% for RT95, and 2% for RA95. Future projections show a

  13. DspaceOgreTerrain 3D Terrain Visualization Tool

    NASA Technical Reports Server (NTRS)

    Myint, Steven; Jain, Abhinandan; Pomerantz, Marc I.

    2012-01-01

    DspaceOgreTerrain is an extension to the DspaceOgre 3D visualization tool that supports real-time visualization of various terrain types, including digital elevation maps, planets, and meshes. DspaceOgreTerrain supports creating 3D representations of terrains and placing them in a scene graph. The 3D representations allow for a continuous level of detail, GPU-based rendering, and overlaying graphics like wheel tracks and shadows. It supports reading data from the SimScape terrain- modeling library. DspaceOgreTerrain solves the problem of displaying the results of simulations that involve very large terrains. In the past, it has been used to visualize simulations of vehicle traverses on Lunar and Martian terrains. These terrains were made up of billions of vertices and would not have been renderable in real-time without using a continuous level of detail rendering technique.

  14. Sakhalin Island terrain intelligence

    USGS Publications Warehouse

    ,

    1943-01-01

    This folio of maps and explanatory tables outlines the principal terrain features of Sakhalin Island. Each map and table is devoted to a specialized set of problems; together they cover the subjects of terrain appreciation, climate, rivers, water supply, construction materials, suitability for roads, suitability for airfields, fuels and other mineral resources, and geology. In most cases, the map of the island is divided into two parts: N. of latitude 50° N., Russian Sakhalin, and south of latitude 50° N., Japanese Sakhalin or Karafuto. These maps and data were compiled by the United States Geological Survey during the period from March to September, 1943.

  15. Hybrid Terrain Database

    NASA Technical Reports Server (NTRS)

    Arthur, Trey

    2006-01-01

    A prototype hybrid terrain database is being developed in conjunction with other databases and with hardware and software that constitute subsystems of aerospace cockpit display systems (known in the art as synthetic vision systems) that generate images to increase pilots' situation awareness and eliminate poor visibility as a cause of aviation accidents. The basic idea is to provide a clear view of the world around an aircraft by displaying computer-generated imagery derived from an onboard database of terrain, obstacle, and airport information.

  16. Very low frequency electromagnetic (VLF-EM) and electrical resistivity (ER) investigation for groundwater potential evaluation in a complex geological terrain around the Ijebu-Ode transition zone, southwestern Nigeria

    NASA Astrophysics Data System (ADS)

    Osinowo, Olawale O.; Idowu Olayinka, A.

    2012-08-01

    Groundwater exploration in either a basement or sedimentary environment is often fairly well defined and focuses on delineating weathered/fractured rocks or saturated formations, respectively. Conversely, unique geological structures, the complex coexistence of different rock types and poorly defined basal/lateral contacts between basement and sedimentary rocks make groundwater development in a geological transition environment very challenging. Ijebu-Ode and its environs lie within such a problematic transition zone, between the Precambrian basement rocks and Cretaceous sediments of the Dahomey Basin, in southwestern Nigeria, where associated acute groundwater development challenges require adequate subsurface information to maximize its groundwater resource potential. This study integrated very low frequency electromagnetic (VLF-EM) and electrical resistivity (ER) geophysical prospecting techniques for a detailed terrain study of Ijebu-Ode in order to establish the reasons for the low groundwater resource potential in the area. Thirty five VLF-EM profiles, 140 vertical electrical soundings (VES) and relevant hydrogeological data were acquired along grids and profiles. Data were filtered, inverted and enhanced using appropriate software packages. The current density and geoelectric parameters of the VLF-EM and VES data were employed to generate terrain maps, the conductivity distribution and a subsurface basement model of the study area. Current density plots and geoelectric parameters identified up to three layers in the basement complex terrain which comprised lateritic topsoil, weathered basement and fresh basement rocks. The five layers encountered in the sedimentary terrain were topsoil, a lateritic unit, a dry sandy unit, a saturated sandy unit and fresh basement rocks. The hydraulic conductivity of the thick (3-18 m) lateritic unit was determined to be 1.32 × 10-5 mm s-1, while that of the underlying sandy units ranged from 2.65 × 10-4 to 1.36 × 10-3 mm

  17. Resolving Extreme Rainfall from Space: A New Class of Algorithms for Precipitation Retrieval and Data Fusion/Assimilation with Emphasis on Extremes over Complex Terrain and Coastal Areas

    NASA Astrophysics Data System (ADS)

    Foufoula-Georgiou, E.; Ebtehaj, A.

    2015-12-01

    The increasing availability of precipitation observations from the Global Precipitation Measuring (GPM) Mission, has fueled renewed interest in developing frameworks for accurate estimation of precipitation extremes especially over ungauged mountainous terrains and coastal regions to improve hydro-geological hazard prediction and control. Our recent research has shown that treating precipitation retrieval and data fusion/assimilation as inverse problems and using a regularized variational approach with the regularization term(s) selected to impose desired smoothness in the solution, leads to improved representation of extremes. Here we present some new theoretical and computational developments which extend the ideas to a model-agnostic framework of retrieval via a regularized search within properly constructed data bases. We test the framework in several tropical storms over the Ganges-Brahmaputra delta region and over the Himalayas and compare the results with the standard retrieval algorithms currently used for operational purposes.

  18. Vegetation and terrain mapping in Alaska using Landsat MSS and digital terrain data

    USGS Publications Warehouse

    Shasby, Mark; Carneggie, David M.

    1986-01-01

    During the past 5 years, the U.S. Geological Survey's (USGS) Earth Resources Observation Systems (EROS) Data Center Field Office in Anchorage, Alaska has worked cooperatively with Federal and State resource management agencies to produce land-cover and terrain maps for 245 million acres of Alaska. The need for current land-cover information in Alaska comes principally from the mandates of the Alaska National Interest Lands Conservation Act (ANILCA), December 1980, which requires major land management agencies to prepare comprehensive management plans. The land-cover mapping projects integrate digital Landsat data, terrain data, aerial photographs, and field data. The resultant land-cover and terrain maps and associated data bases are used for resource assessment, management, and planning by many Alaskan agencies including the U.S. Fish and Wildlife Service, U.S. Forest Service, Bureau of Land Management, and Alaska Department of Natural Resources. Applications addressed through use of the digital land-cover and terrain data bases range from comprehensive refuge planning to multiphased sampling procedures designed to inventory vegetation statewide. The land-cover mapping programs in Alaska demonstrate the operational utility of digital Landsat data and have resulted in a new land-cover mapping program by the USGS National Mapping Division to compile 1:250,000-scale land-cover maps in Alaska using a common statewide land-cover map legend.

  19. Terrain perception for robot navigation

    NASA Astrophysics Data System (ADS)

    Karlsen, Robert E.; Witus, Gary

    2007-04-01

    This paper presents a method to forecast terrain trafficability from visual appearance. During training, the system identifies a set of image chips (or exemplars) that span the range of terrain appearance. Each chip is assigned a vector tag of vehicle-terrain interaction characteristics that are obtained from simple performance models and on-board sensors, as the vehicle traverses the terrain. The system uses the exemplars to segment images into regions, based on visual similarity to the terrain patches observed during training, and assigns the appropriate vehicle-terrain interaction tag to them. This methodology will therefore allow the online forecasting of vehicle performance on upcoming terrain. Currently, the system uses a fuzzy c-means clustering algorithm for training. In this paper, we explore a number of different features for characterizing the visual appearance of the terrain and measure their effect on the prediction of vehicle performance.

  20. Fretted Terrain Valleys

    NASA Technical Reports Server (NTRS)

    2004-01-01

    30 October 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows shallow tributary valleys in the Ismenius Lacus fretted terrain region of northern Arabia Terra. These valleys exhibit a variety of typical fretted terrain valley wall and floor textures, including a lineated, pitted material somewhat reminiscent of the surface of a brain. Origins for these features are still being debated within the Mars science community; there are no clear analogs to these landforms on Earth. This image is located near 39.9oN, 332.1oW. The picture covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.

  1. 76 FR 54527 - Ninth Meeting-RTCA Special Committee 217: Joint With EUROCAE WG-44 Terrain and Airport Mapping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-01

    ... Terrain and Airport Mapping Databases AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of RTCA Special Committee 217: Joint with EUROCAE WG-44 Terrain and Airport Mapping Databases...: Joint with EUROCAE WG-44 Terrain and Airport Mapping Databases. DATES: The meeting will be...

  2. 75 FR 59327 - Seventh Meeting-RTCA Special Committee 217: Joint With EUROCAE WG-44 Terrain and Airport Mapping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-27

    ... Terrain and Airport Mapping Databases AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of RTCA Special Committee 217: Joint with EUROCAE WG-44 Terrain and Airport Mapping Databases...: Joint with EUROCAE WG-44 Terrain and Airport Mapping Databases. DATES: The meeting will be held...

  3. 76 FR 27744 - Eighth Meeting-RTCA Special Committee 217: Joint With EUROCAE WG-44 Terrain and Airport Mapping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-12

    ... Terrain and Airport Mapping Databases AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of RTCA Special Committee 217: Joint with EUROCAE WG-44 Terrain and Airport Mapping Databases...: Joint with EUROCAE WG-44 Terrain and Airport Mapping Databases. DATES: The meeting will be held June...

  4. 77 FR 29749 - Twelfth Meeting: RTCA Special Committee 217, Joint with EUROCAE WG-44, Terrain and Airport...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-18

    ..., Terrain and Airport Mapping Databases AGENCY: Federal Aviation Administration (FAA), U.S. Department of Transportation (DOT). ACTION: Meeting Notice of RTCA Special Committee 217, Joint with EUROCAE WG-44, Terrain and... meeting, RTCA Special Committee 217, Joint with EUROCAE WG-44, Terrain and Airport Mapping...

  5. 76 FR 6179 - Eighth Meeting-RTCA Special Committee 217: Joint With EUROCAE WG-44 Terrain and Airport Mapping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-03

    ...-44 Terrain and Airport Mapping Databases AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of RTCA Special Committee 217: Joint with EUROCAE WG-44 Terrain and Airport Mapping Databases...: Joint with EUROCAE WG-44 Terrain and Airport Mapping Databases. DATES: The meeting will be held...

  6. 75 FR 10552 - Sixth Meeting-RTCA Special Committee 217: Joint With EUROCAE WG-44 Terrain and Airport Mapping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-08

    ... Terrain and Airport Mapping Databases AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of RTCA Special Committee 217: Joint with EUROCAE WG-44 Terrain and Airport Mapping Databases...: Joint with EUROCAE WG-44 Terrain and Airport Mapping Databases. DATES: The meeting will be held on...

  7. Spatial patterning in PM2.5 constituents under an inversion-focused sampling design across an urban area of complex terrain.

    PubMed

    Tunno, Brett J; Dalton, Rebecca; Michanowicz, Drew R; Shmool, Jessie L C; Kinnee, Ellen; Tripathy, Sheila; Cambal, Leah; Clougherty, Jane E

    2016-06-01

    Health effects of fine particulate matter (PM2.5) vary by chemical composition, and composition can help to identify key PM2.5 sources across urban areas. Further, this intra-urban spatial variation in concentrations and composition may vary with meteorological conditions (e.g., mixing height). Accordingly, we hypothesized that spatial sampling during atmospheric inversions would help to better identify localized source effects, and reveal more distinct spatial patterns in key constituents. We designed a 2-year monitoring campaign to capture fine-scale intra-urban variability in PM2.5 composition across Pittsburgh, PA, and compared both spatial patterns and source effects during "frequent inversion" hours vs 24-h weeklong averages. Using spatially distributed programmable monitors, and a geographic information systems (GIS)-based design, we collected PM2.5 samples across 37 sampling locations per year to capture variation in local pollution sources (e.g., proximity to industry, traffic density) and terrain (e.g., elevation). We used inductively coupled plasma mass spectrometry (ICP-MS) to determine elemental composition, and unconstrained factor analysis to identify source suites by sampling scheme and season. We examined spatial patterning in source factors using land use regression (LUR), wherein GIS-based source indicators served to corroborate factor interpretations. Under both summer sampling regimes, and for winter inversion-focused sampling, we identified six source factors, characterized by tracers associated with brake and tire wear, steel-making, soil and road dust, coal, diesel exhaust, and vehicular emissions. For winter 24-h samples, four factors suggested traffic/fuel oil, traffic emissions, coal/industry, and steel-making sources. In LURs, as hypothesized, GIS-based source terms better explained spatial variability in inversion-focused samples, including a greater contribution from roadway, steel, and coal-related sources. Factor analysis produced

  8. Spatial patterning in PM2.5 constituents under an inversion-focused sampling design across an urban area of complex terrain.

    PubMed

    Tunno, Brett J; Dalton, Rebecca; Michanowicz, Drew R; Shmool, Jessie L C; Kinnee, Ellen; Tripathy, Sheila; Cambal, Leah; Clougherty, Jane E

    2016-06-01

    Health effects of fine particulate matter (PM2.5) vary by chemical composition, and composition can help to identify key PM2.5 sources across urban areas. Further, this intra-urban spatial variation in concentrations and composition may vary with meteorological conditions (e.g., mixing height). Accordingly, we hypothesized that spatial sampling during atmospheric inversions would help to better identify localized source effects, and reveal more distinct spatial patterns in key constituents. We designed a 2-year monitoring campaign to capture fine-scale intra-urban variability in PM2.5 composition across Pittsburgh, PA, and compared both spatial patterns and source effects during "frequent inversion" hours vs 24-h weeklong averages. Using spatially distributed programmable monitors, and a geographic information systems (GIS)-based design, we collected PM2.5 samples across 37 sampling locations per year to capture variation in local pollution sources (e.g., proximity to industry, traffic density) and terrain (e.g., elevation). We used inductively coupled plasma mass spectrometry (ICP-MS) to determine elemental composition, and unconstrained factor analysis to identify source suites by sampling scheme and season. We examined spatial patterning in source factors using land use regression (LUR), wherein GIS-based source indicators served to corroborate factor interpretations. Under both summer sampling regimes, and for winter inversion-focused sampling, we identified six source factors, characterized by tracers associated with brake and tire wear, steel-making, soil and road dust, coal, diesel exhaust, and vehicular emissions. For winter 24-h samples, four factors suggested traffic/fuel oil, traffic emissions, coal/industry, and steel-making sources. In LURs, as hypothesized, GIS-based source terms better explained spatial variability in inversion-focused samples, including a greater contribution from roadway, steel, and coal-related sources. Factor analysis produced

  9. Spatial patterning in PM2.5 constituents under an inversion-focused sampling design across an urban area of complex terrain

    PubMed Central

    Tunno, Brett J; Dalton, Rebecca; Michanowicz, Drew R; Shmool, Jessie L C; Kinnee, Ellen; Tripathy, Sheila; Cambal, Leah; Clougherty, Jane E

    2016-01-01

    Health effects of fine particulate matter (PM2.5) vary by chemical composition, and composition can help to identify key PM2.5 sources across urban areas. Further, this intra-urban spatial variation in concentrations and composition may vary with meteorological conditions (e.g., mixing height). Accordingly, we hypothesized that spatial sampling during atmospheric inversions would help to better identify localized source effects, and reveal more distinct spatial patterns in key constituents. We designed a 2-year monitoring campaign to capture fine-scale intra-urban variability in PM2.5 composition across Pittsburgh, PA, and compared both spatial patterns and source effects during “frequent inversion” hours vs 24-h weeklong averages. Using spatially distributed programmable monitors, and a geographic information systems (GIS)-based design, we collected PM2.5 samples across 37 sampling locations per year to capture variation in local pollution sources (e.g., proximity to industry, traffic density) and terrain (e.g., elevation). We used inductively coupled plasma mass spectrometry (ICP-MS) to determine elemental composition, and unconstrained factor analysis to identify source suites by sampling scheme and season. We examined spatial patterning in source factors using land use regression (LUR), wherein GIS-based source indicators served to corroborate factor interpretations. Under both summer sampling regimes, and for winter inversion-focused sampling, we identified six source factors, characterized by tracers associated with brake and tire wear, steel-making, soil and road dust, coal, diesel exhaust, and vehicular emissions. For winter 24-h samples, four factors suggested traffic/fuel oil, traffic emissions, coal/industry, and steel-making sources. In LURs, as hypothesized, GIS-based source terms better explained spatial variability in inversion-focused samples, including a greater contribution from roadway, steel, and coal-related sources. Factor analysis

  10. Managing Cooperation and Complexity in Education: The Case of Educational Service Agencies. Final Report.

    ERIC Educational Resources Information Center

    Weiss, Janet A.; And Others

    Educational Service Agencies (ESA's) are public education agencies that provide specialized programs and services to a group of school districts in a specified geographical region and to the state department of education. Most states have encouraged the development of ESA's that have either evolved out of county districts or have been created to…

  11. Statistical Modeling of Robotic Random Walks on Different Terrain

    NASA Astrophysics Data System (ADS)

    Naylor, Austin; Kinnaman, Laura

    Issues of public safety, especially with crowd dynamics and pedestrian movement, have been modeled by physicists using methods from statistical mechanics over the last few years. Complex decision making of humans moving on different terrains can be modeled using random walks (RW) and correlated random walks (CRW). The effect of different terrains, such as a constant increasing slope, on RW and CRW was explored. LEGO robots were programmed to make RW and CRW with uniform step sizes. Level ground tests demonstrated that the robots had the expected step size distribution and correlation angles (for CRW). The mean square displacement was calculated for each RW and CRW on different terrains and matched expected trends. The step size distribution was determined to change based on the terrain; theoretical predictions for the step size distribution were made for various simple terrains. It's Dr. Laura Kinnaman, not sure where to put the Prefix.

  12. Scannerless terrain mapper

    SciTech Connect

    Sackos, J.; Bradley, B.; Diegert, C.; Ma, P.; Gary, C.

    1996-09-01

    NASA-Ames Research Center, in collaboration with Sandia National Laboratories, is developing a Scannerless Terrain Mapper (STM) for autonomous vehicle guidance through the use of virtual reality. The STM sensor is based on an innovative imaging optical radar technology that is being developed by Sandia National Laboratories. The sensor uses active flood-light scene illumination and an image intensified CCD camera receiver to rapidly produce and record very high quality range imagery of observed scenes. The STM is an all solid-state device (containing no moving parts) and offers significant size, performance, reliability, simplicity, and affordability advantages over other types of 3-D sensor technologies, such as scanned laser radar, stereo vision, and structured lighting. The sensor is based on low cost, commercially available hardware, and is very well suited for affordable application to a wide variety of military and commercial uses, including: munition guidance, target recognition, robotic vision, automated inspection, driver enhanced vision, collision avoidance, site security and monitoring, and facility surveying. This paper reviews the sensor technology, discusses NASA`s terrain mapping applications, and presents results from the initial testing of the sensor at NASA`s planetary landscape simulator.

  13. Fretted Terrain Valley Floor

    NASA Technical Reports Server (NTRS)

    2004-01-01

    30 December 2003 This December 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows lineated textures on the floor of a valley in the Deuteronilus region of Mars. Deuteronilus, and neighboring Protonilus and Nilosyrtis, have been known since the Mariner 9 mission as regions of 'fretted terrain.' In this context, 'fretted' does not mean 'worried,' it means 'eroded.' The fretted terrains of Mars are regions along the boundary between cratered highlands and northern lowland plains that have been broken-down into mesas, buttes, and valleys. On the floors of some of these valleys occurs a distinctive lineated and pitted texture--like the example shown here. The cause of the textures is not known, although for decades some scientists have speculated that ice is involved. While this is possible, it is far from a demonstrated fact. This picture is located near 40.1oN, 335.1oW, and covers an area approximately 3 km (1.9 mi) wide; sunlight illuminates the scene from the lower left.

  14. Eastern Siberia terrain intelligence

    USGS Publications Warehouse

    ,

    1942-01-01

    The following folio of terrain intelligence maps, charts and explanatory tables represent an attempt to bring together available data on natural physical conditions such as will affect military operations in Eastern Siberia. The area covered is the easternmost section of the U.S.S.R.; that is the area east of the Yenisei River. Each map and accompanying table is devoted· to a specialized set of problems; together they cover such subjects as geology, construction materials, mineral fuels, terrain, water supply, rivers and climate. The data is somewhat generalized due to the scale of treatment as well as to the scarcity of basic data. Each of the maps are rated as to reliability according to the reliability scale on the following page. Considerable of the data shown is of an interpretative nature, although precise data from literature was used wherever possible. The maps and tables were compiled  by a special group from the United States Geological Survey in cooperation with the Intelligence Branch of the Office, Chief of Engineers, War Department.

  15. Extracting mineral system event histories from geophysical and geochemical data in geologically complex terrain - an example from the southeastern Fennoscandian Shield.

    NASA Astrophysics Data System (ADS)

    Sorjonen-Ward, Peter; Kontinen, Asko; Lerssi, Jouni; Mertanen, Satu; Molnar, Ferenc; O'Brien, Hugh; Pohjolainen, Esa; Halla, Jaana; Korhonen, Fawna; Mattila, Jussi

    2015-04-01

    The mineral systems concept is intended to extend and inform exploration capability, through understanding processes of metal extraction, transport and precipitation within a well-defined architectural framework, as opposed to simple - or even sophisticated - targeting of geophysical or geochemical anomalies. Given that geophysical and geochemical data represent a summation of all events and processes that have affected a body of rock, the use of advanced inversion techniques could be impeded unless we can extract an accurate event history and derive a comprehensive understanding of the history of hydrothermal events and their structural framework, even in a qualitative sense. In ideal cases, we may be able to place age constraints using isotopes or paleomagnetism, if hydrothermal mineral reactions enhance (or disperse) geochemical and geophysical signals. Given a the tendency for deformation in the brittle regime to occur preferentially by reactivation of existing zones of weakness, we might also expect a progressive linear enhancement or dilution of anomalies, where fluid-flow is focused within permeable fault zones. We illustrate these issues through an analysis of event histories and their relationship to diverse mineralization styles and episodes in the southeastern part of the Fennoscandian Shield, where the oldest mineral systems are represented by orogenic gold deposits in Neoarchean greenstone belts and the youngest events are recorded locally by Paleozoic crystallization of uraninite in repeatedly reactivated fault zones. The Neoarchean Karelian craton was subjected to thermal reworking as the foreland terrain to the 1.9-1.8 Ga Svecofennian Orogeny, as demonstrated by resetting of K-Ar, Ar-Ar, Rb-Sr and locally Pb-Pb isotopic systems in feldspars and pyrite, both within gold deposits, and regionally. However, retention of Archean strain patterns and observations of the strain state of Proterozoifc dyke swarms indicate an essentially brittle response, with

  16. Flat Top & rocky terrain

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Flat Top, the rectangular rock at lower right, is part of a stretch of rocky terrain in this image, taken by the deployed Imager for Mars Pathfinder (IMP) on Sol 3. Dust has accumulated on the top of Flat Top, but is not present on the sides due to the steep angles of the rock. This dust may have been placed by dust storms moving across the Martian surface. Flat Top has been studied using several different color filters on the IMP camera.

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C.

  17. Mars Terrain Generation

    NASA Technical Reports Server (NTRS)

    Deen, Robert G.

    2010-01-01

    A suite of programs for the generation of disparity maps from stereo image pairs via correlation, and conversion of those disparity maps to XYZ maps, has been updated. This suite implements an automated method of deriving terrain from stereo images for use in the ground data system for in-situ (lander and rover) cameras. This differs from onboard correlation by concentrating more on accuracy than speed, since near-real-time is not a requirement on the ground. The final result is an XYZ value for every point in the image that passes several quality checks. A priori geometric camera calibration information is required for this suite to operate. The suite is very flexible, enabling its use in many special situations, such as non-linearized images required for applications like the Phoenix arm camera, or long-baseline stereo, where the rover moves between left and right images.

  18. Prediction of a Flash Flood in Complex Terrain. Part I: A Comparison of Rainfall Estimates from Radar, and Very Short Range Rainfall Simulations from a Dynamic Model and an Automated Algorithmic System.

    NASA Astrophysics Data System (ADS)

    Warner, Thomas T.; Brandes, Edward A.; Sun, Juanzhen; Yates, David N.; Mueller, Cynthia K.

    2000-06-01

    Operational prediction of flash floods caused by convective rainfall in mountainous areas requires accurate estimates or predictions of the rainfall distribution in space and time. The details of the spatial distribution are especially critical in complex terrain because the watersheds generally are small in size, and position errors in the placement of the rainfall can distribute the rain over the wrong watershed. In addition to the need for good rainfall estimates, accurate flood prediction requires a surface-hydrologic model that is capable of predicting stream or river discharge based on the rainfall-rate input data. In part 1 of this study, different techniques for the estimation and prediction of convective rainfall are applied to the Buffalo Creek, Colorado, flash flood of July 1996, during which over 75 mm of rain from a thunderstorm fell on the watershed in less than 1 h. The hydrologic impact of the rainfall was exacerbated by the fact that a considerable fraction of the watershed experienced a wildfire approximately two months prior to the rain event.Precipitation estimates from the National Weather Service Weather Surveillance Radar-1988 Doppler and the National Center for Atmospheric Research S-band, dual-polarization radar, collocated east of Denver, Colorado, were compared. Very short range simulations from a convection-resolving dynamic model that was initialized variationally using the radar reflectivity and Doppler winds were compared with simulations from an automated algorithmic forecast system that also employs the radar data. The radar estimates of rain rate and the two forecasting systems that employ the radar data have degraded accuracy by virtue of the fact that they are applied in complex terrain. Nevertheless, the dynamic model and automated algorithms both produce simulations that could be useful operationally for input to surface-hydrologic models employed for flood warning. Part 2 of this study, reported in a companion paper, describes

  19. On the Complexity of Digital Video Cameras in/as Research: Perspectives and Agencements

    ERIC Educational Resources Information Center

    Bangou, Francis

    2014-01-01

    The goal of this article is to consider the potential for digital video cameras to produce as part of a research agencement. Our reflection will be guided by the current literature on the use of video recordings in research, as well as by the rhizoanalysis of two vignettes. The first of these vignettes is associated with a short video clip shot by…

  20. Radiometric terrain correction of SPOT5 image

    NASA Astrophysics Data System (ADS)

    Feng, Xiuli; Zhang, Feng; Wang, Ke

    2007-06-01

    terrain correction model based on the rationale of moment matching is an effective model to reduce the shade effect than the traditional C correction approach, especially in the complex undulation of mountain area with lots of shade effect. In other words, the traditional C correction approach will show the better result at the plain area with less shade effect. Besides, the accuracy of the DEM data and the registration accuracy between the image and the DEM data will also influence the final correction accuracy. In order to achieve the higher radiometric terrain correction, high spatial resolution DEM data is preferred.

  1. Environmental impacts of forest road construction on mountainous terrain

    PubMed Central

    2013-01-01

    Forest roads are the base infrastructure foundation of forestry operations. These roads entail a complex engineering effort because they can cause substantial environmental damage to forests and include a high-cost construction. This study was carried out in four sample sites of Giresun, Trabzon(2) and Artvin Forest Directorate, which is in the Black Sea region of Turkey. The areas have both steep terrain (30-50% gradient) and very steep terrain (51-80% gradient). Bulldozers and hydraulic excavators were determined to be the main machines for forest road construction, causing environmental damage and cross sections in mountainous areas. As a result of this study, the percent damage to forests was determined as follows: on steep terrain, 21% of trees were damaged by excavators and 33% of trees were damaged by bulldozers during forest road construction, and on very steep terrain, 27% of trees were damaged by excavators and 44% of trees were damaged by bulldozers during forest road construction. It was also determined that on steep terrain, when excavators were used, 12.23% less forest area was destroyed compared with when bulldozers were used and 16.13% less area was destroyed by excavators on very steep terrain. In order to reduce the environmental damage on the forest ecosystem, especially in steep terrains, hydraulic excavators should replace bulldozers in forest road construction activities. PMID:23497078

  2. Environmental impacts of forest road construction on mountainous terrain.

    PubMed

    Caliskan, Erhan

    2013-01-01

    Forest roads are the base infrastructure foundation of forestry operations. These roads entail a complex engineering effort because they can cause substantial environmental damage to forests and include a high-cost construction. This study was carried out in four sample sites of Giresun, Trabzon(2) and Artvin Forest Directorate, which is in the Black Sea region of Turkey. The areas have both steep terrain (30-50% gradient) and very steep terrain (51-80% gradient). Bulldozers and hydraulic excavators were determined to be the main machines for forest road construction, causing environmental damage and cross sections in mountainous areas.As a result of this study, the percent damage to forests was determined as follows: on steep terrain, 21% of trees were damaged by excavators and 33% of trees were damaged by bulldozers during forest road construction, and on very steep terrain, 27% of trees were damaged by excavators and 44% of trees were damaged by bulldozers during forest road construction. It was also determined that on steep terrain, when excavators were used, 12.23% less forest area was destroyed compared with when bulldozers were used and 16.13% less area was destroyed by excavators on very steep terrain. In order to reduce the environmental damage on the forest ecosystem, especially in steep terrains, hydraulic excavators should replace bulldozers in forest road construction activities. PMID:23497078

  3. Environmental impacts of forest road construction on mountainous terrain.

    PubMed

    Caliskan, Erhan

    2013-03-15

    Forest roads are the base infrastructure foundation of forestry operations. These roads entail a complex engineering effort because they can cause substantial environmental damage to forests and include a high-cost construction. This study was carried out in four sample sites of Giresun, Trabzon(2) and Artvin Forest Directorate, which is in the Black Sea region of Turkey. The areas have both steep terrain (30-50% gradient) and very steep terrain (51-80% gradient). Bulldozers and hydraulic excavators were determined to be the main machines for forest road construction, causing environmental damage and cross sections in mountainous areas.As a result of this study, the percent damage to forests was determined as follows: on steep terrain, 21% of trees were damaged by excavators and 33% of trees were damaged by bulldozers during forest road construction, and on very steep terrain, 27% of trees were damaged by excavators and 44% of trees were damaged by bulldozers during forest road construction. It was also determined that on steep terrain, when excavators were used, 12.23% less forest area was destroyed compared with when bulldozers were used and 16.13% less area was destroyed by excavators on very steep terrain. In order to reduce the environmental damage on the forest ecosystem, especially in steep terrains, hydraulic excavators should replace bulldozers in forest road construction activities.

  4. The Relevance of Surface Roughness Data Qualities in Diagnostic Modeling of Wind Velocity in Complex Terrain: A Case Study from the Śnieżnik Massif (SW Poland)

    NASA Astrophysics Data System (ADS)

    Jancewicz, Kacper; Szymanowski, Mariusz

    2016-04-01

    Numerical modeling of wind velocity above complex terrain has become a subject of numerous contemporary studies. Regardless of the methodical approach (dynamic or diagnostic), it can be observed that information about surface roughness is indispensable to achieve realistic results. In this context, the current state of GIS and remote sensing development allows access to a number of datasets providing information about various properties of land coverage in a broad spectrum of spatial resolution. Hence, the quality of roughness information may vary depending on the properties of primary land coverage data. As a consequence, the results of the wind velocity modeling are affected by the accuracy and spatial resolution of roughness data. This paper describes further attempts to model wind velocity using the following sources of roughness information: LiDAR data (Digital Surface Model and Digital Terrain Model), database of topographical objects (BDOT10k) and both raster and vector versions of Corine Land Cover 2006 (CLC). The modeling was conducted in WindStation 4.0.2 software which is based on the computational fluid dynamics (CFD) diagnostic solver Canyon. Presented experiment concerns three episodes of relatively strong and constant synoptic forcing: 26 November 2011, 25 May 2012 and 26 May 2012. The modeling was performed in the spatial resolution of 50 and 100 m. Input anemological data were collected during field measurements while the atmosphere boundary layer parameters were derived from the meteorological stations closest to the study area. The model's performance was verified using leave-one-out cross-validation and calculation of error indices such as bias error, root mean square error and index of wind speed. Thus, it was possible to compare results of using roughness datasets of different type and resolution. The study demonstrates that the use of LiDAR-based roughness data may result in an improvement of the model's performance in 100 and 50 m resolution

  5. A field study for the validation and implementation of the urban airshed model (UAM) in the complex terrain surrounding Salt Lake City, Utah

    SciTech Connect

    Swart, H.R.; Barickman, P.R.; Wilkerson, G.W.; Hauze, W.

    1998-12-31

    Historically the Wasatch Front has exceeded the existing one-hour ozone standard, and is expected to have difficulty meeting the new 8-hour standard. To better understand and forecast these exceedance episodes the Utah Division of Air Quality (UDAQ) has elected to apply the Urban Airshed Model (UAM). The application of UAM in this area is difficult because of the Wasatch mountain range to the east of the urbanized area and the Great Salt Lake to the west. The UDAQ sponsored a field data measurement project during the summer of 1996 to support the UAM effort. Special intensive measurements of meteorology, precursor emissions, and chemistry, at ground level and aloft, were conducted on five days to develop a more complete understanding of ozone and its evolutionary process. Aircraft and ground-based mobile measurements of air quality and meteorology supplemented the existing networks to define the boundary conditions as well as document the chemical changes and transport within the airshed. On the study days ozone concentrations did not exceed the 1-hour standard but did exceed the 8-hour standard. The field effort has provided valuable data for characterizing the complex meteorology and boundary conditions in the airshed. This paper discusses the data analysis as it applies to the development of wind fields with the Diagnostic Wind Model (DWM)1 for use in the UAM.

  6. Performance of complex snow cover descriptions in a distributed hydrological model system: A case study for the high Alpine terrain of the Berchtesgaden Alps

    PubMed Central

    Warscher, M; Strasser, U; Kraller, G; Marke, T; Franz, H; Kunstmann, H

    2013-01-01

    [1] Runoff generation in Alpine regions is typically affected by snow processes. Snow accumulation, storage, redistribution, and ablation control the availability of water. In this study, several robust parameterizations describing snow processes in Alpine environments were implemented in a fully distributed, physically based hydrological model. Snow cover development is simulated using different methods from a simple temperature index approach, followed by an energy balance scheme, to additionally accounting for gravitational and wind-driven lateral snow redistribution. Test site for the study is the Berchtesgaden National Park (Bavarian Alps, Germany) which is characterized by extreme topography and climate conditions. The performance of the model system in reproducing snow cover dynamics and resulting discharge generation is analyzed and validated via measurements of snow water equivalent and snow depth, satellite-based remote sensing data, and runoff gauge data. Model efficiency (the Nash-Sutcliffe coefficient) for simulated runoff increases from 0.57 to 0.68 in a high Alpine headwater catchment and from 0.62 to 0.64 in total with increasing snow model complexity. In particular, the results show that the introduction of the energy balance scheme reproduces daily fluctuations in the snowmelt rates that trace down to the channel stream. These daily cycles measured in snowmelt and resulting runoff rates could not be reproduced by using the temperature index approach. In addition, accounting for lateral snow transport changes the seasonal distribution of modeled snowmelt amounts, which leads to a higher accuracy in modeling runoff characteristics. PMID:24223443

  7. Mars digital terrain model

    NASA Technical Reports Server (NTRS)

    Wu, Sherman S. C.; Howington, Annie-Elpis

    1987-01-01

    The Mars Digital Terrain Model (DTM) is the result of a new project to: (1) digitize the series of 1:2,000,000-scale topographic maps of Mars, which are being derived photogrammetically under a separate project, and (2) reformat the digital contour information into rasters of elevation that can be readily registered with the Digital Image Model (DIM) of Mars. Derivation of DTM's involves interpolation of elevation values into 1/64-degree resolution and transformation of them to a sinusoidal equal-area projection. Digital data are produced in blocks corresponding with the coordinates of the original 1:2,000,000-scale maps, i.e., the dimensions of each block in the equatorial belt are 22.5 deg of longitude and 15 deg of latitude. This DTM is not only compatible with the DIM, but it can also be registered with other data such as geologic units or gravity. It will be the most comprehensive record of topographic information yet compiled for the Martian surface. Once the DTM's are established, any enhancement of Mars topographic information made with updated data, such as data from the planned Mars Observer Mission, will be by mathematical transformation of the DTM's, eliminating the need for recompilation.

  8. Martian terrain - 3D

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This area of terrain near the Sagan Memorial Station was taken on Sol 3 by the Imager for Mars Pathfinder (IMP). 3D glasses are necessary to identify surface detail.

    The IMP is a stereo imaging system with color capability provided by 24 selectable filters -- twelve filters per 'eye.' It stands 1.8 meters above the Martian surface, and has a resolution of two millimeters at a range of two meters.

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is an operating division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.

    Click below to see the left and right views individually. [figure removed for brevity, see original site] Left [figure removed for brevity, see original site] Right

  9. Parkview opens a new hospital. Fort Wayne, Ind., hospital works with agency in complex compaign.

    PubMed

    Botvin, Judith D

    2003-01-01

    Parkview Health, Forth Wayne, Ind., recently opened its new primary care hospital, Parkview North, an expansion of the services of its flagship Parkview Hospital. But the grand opening event was only one focus of the integrated advertising campaign, which also included a component to recruit staff. In view of the nationwide shortage of nurses, marketers faced the need for 200 nurses to staff the new facility. With its agency, Ten Adams, of Evansville, Ind., Parkview succeeded in opening its new hospital with a full complement of nurses.

  10. Parkview opens a new hospital. Fort Wayne, Ind., hospital works with agency in complex compaign.

    PubMed

    Botvin, Judith D

    2003-01-01

    Parkview Health, Forth Wayne, Ind., recently opened its new primary care hospital, Parkview North, an expansion of the services of its flagship Parkview Hospital. But the grand opening event was only one focus of the integrated advertising campaign, which also included a component to recruit staff. In view of the nationwide shortage of nurses, marketers faced the need for 200 nurses to staff the new facility. With its agency, Ten Adams, of Evansville, Ind., Parkview succeeded in opening its new hospital with a full complement of nurses. PMID:12645313

  11. Terrain-Adaptive Navigation Architecture

    NASA Technical Reports Server (NTRS)

    Helmick, Daniel M.; Angelova, Anelia; Matthies, Larry H.; Helmick, Daniel M.

    2008-01-01

    A navigation system designed for a Mars rover has been designed to deal with rough terrain and/or potential slip when evaluating and executing paths. The system also can be used for any off-road, autonomous vehicles. The system enables vehicles to autonomously navigate different terrain challenges including dry river channel systems, putative shorelines, and gullies emanating from canyon walls. Several of the technologies within this innovation increase the navigation system s capabilities compared to earlier rover navigation algorithms.

  12. Dry Ice Etches Terrain

    NASA Technical Reports Server (NTRS)

    2007-01-01

    [figure removed for brevity, see original site] Figure 1

    Every year seasonal carbon dioxide ice, known to us as 'dry ice,' covers the poles of Mars. In the south polar region this ice is translucent, allowing sunlight to pass through and warm the surface below. The ice then sublimes (evaporates) from the bottom of the ice layer, and carves channels in the surface.

    The channels take on many forms. In the subimage shown here (figure 1) the gas from the dry ice has etched wide shallow channels. This region is relatively flat, which may be the reason these channels have a different morphology than the 'spiders' seen in more hummocky terrain.

    Observation Geometry Image PSP_003364_0945 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 15-Apr-2007. The complete image is centered at -85.4 degrees latitude, 104.0 degrees East longitude. The range to the target site was 251.5 km (157.2 miles). At this distance the image scale is 25.2 cm/pixel (with 1 x 1 binning) so objects 75 cm across are resolved. The image shown here has been map-projected to 25 cm/pixel . The image was taken at a local Mars time of 06:57 PM and the scene is illuminated from the west with a solar incidence angle of 75 degrees, thus the sun was about 15 degrees above the horizon. At a solar longitude of 219.6 degrees, the season on Mars is Northern Autumn.

  13. Cryptic Terrain on Mars

    NASA Technical Reports Server (NTRS)

    2007-01-01

    [figure removed for brevity, see original site] Figure 1

    There is an enigmatic region near the south pole of Mars known as the 'cryptic' terrain. It stays cold in the spring, even as its albedo darkens and the sun rises in the sky.

    This region is covered by a layer of translucent seasonal carbon dioxide ice that warms and evaporates from below. As carbon dioxide gas escapes from below the slab of seasonal ice it scours dust from the surface. The gas vents to the surface, where the dust is carried downwind by the prevailing wind.

    The channels carved by the escaping gas are often radially organized and are known informally as 'spiders' (figure 1).

    Observation Geometry Image PSP_003179_0945 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 01-Apr-2007. The complete image is centered at -85.4 degrees latitude, 104.0 degrees East longitude. The range to the target site was 245.9 km (153.7 miles). At this distance the image scale is 49.2 cm/pixel (with 2 x 2 binning) so objects 148 cm across are resolved. The image shown here has been map-projected to 50 cm/pixel . The image was taken at a local Mars time of 06:19 PM and the scene is illuminated from the west with a solar incidence angle of 78 degrees, thus the sun was about 12 degrees above the horizon. At a solar longitude of 210.8 degrees, the season on Mars is Northern Autumn.

  14. Photometric Properties of Enceladus' South Polar Terrain

    NASA Astrophysics Data System (ADS)

    Annex, Andrew; Verbiscer, A. J.; Helfenstein, P.

    2012-10-01

    Cassini images reveal in exquisite detail the complex and varied terrains within the geologically active south pole of Enceladus. The region is dominated by four parallel rifts or sulci, informally known as tiger stripes, from which plumes comprised primarily of water vapor erupt [1,2]. The rich data set of Cassini images acquired at high spatial resolution (< 0.5 km/pixel) and a variety of viewing and illumination geometries enables the quantitative analysis of surface scattering properties through disk-resolved photometry. Here we investigate the photometric properties of individual terrain units [3] through fits of the Hapke photometric model [4] to data acquired in the clear (CL1 CL2), UV3, GRN, and IR3 filters, centered at 0.61, 0.34, 0.57, and 0.93 μm, respectively. Terrain units include the tiger stripe smooth and platy plank formations, tiger stripe medial dorsum structures, relict tiger stripe structures, south pole funiscular (ropy) plains, south pole lateral fold-and-wedge formations, and the south pole reticulated plains. Despite the constant, ubiquitous infall of plume particles onto the surface, differences in scattering properties, texture, and albedo among terrain units can be discerned. Work supported by NASA's Cassini Data Analysis Program. [1] Porco et al. 2006 Science 311, 1393-1401. [2] Hansen et al. 2008 Nature 456, 477-479. [3] Spencer et al. 2009 in Saturn from Cassini-Huygens (M. K. Dougherty et al. Eds.) 683-724. [4] Hapke 2002 Icarus 157, 523-534.

  15. Prediction of a Flash Flood in Complex Terrain. Part II: A Comparison of Flood Discharge Simulations Using Rainfall Input from Radar, a Dynamic Model, and an Automated Algorithmic System.

    NASA Astrophysics Data System (ADS)

    Yates, David N.; Warner, Thomas T.; Leavesley, George H.

    2000-06-01

    Three techniques were employed for the estimation and prediction of precipitation from a thunderstorm that produced a flash flood in the Buffalo Creek watershed located in the mountainous Front Range near Denver, Colorado, on 12 July 1996. The techniques included 1) quantitative precipitation estimation using the National Weather Service's Weather Surveillance Radar-1988 Doppler and the National Center for Atmospheric Research's S-band, dual-polarization radars, 2) quantitative precipitation forecasting utilizing a dynamic model, and 3) quantitative precipitation forecasting using an automated algorithmic system for tracking thunderstorms. Rainfall data provided by these various techniques at short timescales (6 min) and at fine spatial resolutions (150 m to 2 km) served as input to a distributed-parameter hydrologic model for analysis of the flash flood. The quantitative precipitation estimates from the weather radar demonstrated their ability to aid in simulating a watershed's response to precipitation forcing from small-scale, convective weather in complex terrain. That is, with the radar-based quantitative precipitation estimates employed as input, the simulated peak discharge was similar to that estimated. The dynamic model showed the most promise in providing a significant forecast lead time for this flash-flood event. The algorithmic system did not show as much skill in comparison with the dynamic model in providing precipitation forcing to the hydrologic model. The discharge forecasts based on the dynamic-model and algorithmic-system inputs point to the need to improve the ability to forecast convective storms, especially if models such as these eventually are to be used in operational flood forecasting.

  16. Surface energy fluxes in complex terrain

    NASA Technical Reports Server (NTRS)

    Reiter, E. R.; Sheaffer, J. D.; Bossert, J. E.

    1986-01-01

    The emphasis of the 1985 NASA project activity was on field measurements of wind data and heat balance data. Initiatives included a 19 station mountaintop monitoring program, testing and refining the surface flux monitoring systems and packing and shipping equipment to the People's Republic of China in preparation for the 1986 Tibet Experiment. Other work included more extensive analyses of the 1984 Gobi Desert and Rocky Mountain observations plus some preliminary analyses of the 1985 mountaintop network data. Details of our field efforts are summarized and results of our data analyses are presented.

  17. CO2 transport over complex terrain

    USGS Publications Warehouse

    Sun, Jielun; Burns, Sean P.; Delany, A.C.; Oncley, S.P.; Turnipseed, A.A.; Stephens, B.B.; Lenschow, D.H.; LeMone, M.A.; Monson, Russell K.; Anderson, D.E.

    2007-01-01

    CO2 transport processes relevant for estimating net ecosystem exchange (NEE) at the Niwot Ridge AmeriFlux site in the front range of the Rocky Mountains, Colorado, USA, were investigated during a pilot experiment. We found that cold, moist, and CO2-rich air was transported downslope at night and upslope in the early morning at this forest site situated on a ???5% east-facing slope. We found that CO2 advection dominated the total CO2 transport in the NEE estimate at night although there are large uncertainties because of partial cancellation of horizontal and vertical advection. The horizontal CO2 advection captured not only the CO2 loss at night, but also the CO2 uptake during daytime. We found that horizontal CO2 advection was significant even during daytime especially when turbulent mixing was not significant, such as in early morning and evening transition periods and within the canopy. Similar processes can occur anywhere regardless of whether flow is generated by orography, synoptic pressure gradients, or surface heterogeneity as long as CO2 concentration is not well mixed by turbulence. The long-term net effect of all the CO2 budget terms on estimates of NEE needs to be investigated. ?? 2007 Elsevier B.V. All rights reserved.

  18. Terrain mechanical parameters online estimation for lunar rovers

    NASA Astrophysics Data System (ADS)

    Liu, Bing; Cui, Pingyuan; Ju, Hehua

    2007-11-01

    This paper presents a new method for terrain mechanical parameters estimation for a wheeled lunar rover. First, after deducing the detailed distribution expressions of normal stress and sheer stress at the wheel-terrain interface, the force/torque balance equations of the drive wheel for computing terrain mechanical parameters is derived through analyzing the rigid drive wheel of a lunar rover which moves with uniform speed in deformable terrain. Then a two-points Guass-Lengendre numerical integral method is used to simplify the balance equations, after simplifying and rearranging the resolve model are derived which are composed of three non-linear equations. Finally the iterative method of Newton and the steepest descent method are combined to solve the non-linear equations, and the outputs of on-board virtual sensors are used for computing terrain key mechanical parameters i.e. internal friction angle and press-sinkage parameters. Simulation results show correctness under high noises disturbance and effectiveness with low computational complexity, which allows a lunar rover for online terrain mechanical parameters estimation.

  19. Complete scene recovery and terrain classification in textured terrain meshes.

    PubMed

    Song, Wei; Cho, Kyungeun; Um, Kyhyun; Won, Chee Sun; Sim, Sungdae

    2012-01-01

    Terrain classification allows a mobile robot to create an annotated map of its local environment from the three-dimensional (3D) and two-dimensional (2D) datasets collected by its array of sensors, including a GPS receiver, gyroscope, video camera, and range sensor. However, parts of objects that are outside the measurement range of the range sensor will not be detected. To overcome this problem, this paper describes an edge estimation method for complete scene recovery and complete terrain reconstruction. Here, the Gibbs-Markov random field is used to segment the ground from 2D videos and 3D point clouds. Further, a masking method is proposed to classify buildings and trees in a terrain mesh.

  20. Complete Scene Recovery and Terrain Classification in Textured Terrain Meshes

    PubMed Central

    Song, Wei; Cho, Kyungeun; Um, Kyhyun; Won, Chee Sun; Sim, Sungdae

    2012-01-01

    Terrain classification allows a mobile robot to create an annotated map of its local environment from the three-dimensional (3D) and two-dimensional (2D) datasets collected by its array of sensors, including a GPS receiver, gyroscope, video camera, and range sensor. However, parts of objects that are outside the measurement range of the range sensor will not be detected. To overcome this problem, this paper describes an edge estimation method for complete scene recovery and complete terrain reconstruction. Here, the Gibbs-Markov random field is used to segment the ground from 2D videos and 3D point clouds. Further, a masking method is proposed to classify buildings and trees in a terrain mesh. PMID:23112653

  1. Complete scene recovery and terrain classification in textured terrain meshes.

    PubMed

    Song, Wei; Cho, Kyungeun; Um, Kyhyun; Won, Chee Sun; Sim, Sungdae

    2012-01-01

    Terrain classification allows a mobile robot to create an annotated map of its local environment from the three-dimensional (3D) and two-dimensional (2D) datasets collected by its array of sensors, including a GPS receiver, gyroscope, video camera, and range sensor. However, parts of objects that are outside the measurement range of the range sensor will not be detected. To overcome this problem, this paper describes an edge estimation method for complete scene recovery and complete terrain reconstruction. Here, the Gibbs-Markov random field is used to segment the ground from 2D videos and 3D point clouds. Further, a masking method is proposed to classify buildings and trees in a terrain mesh. PMID:23112653

  2. Terrain Corrections for Gravity Gradiometry

    NASA Astrophysics Data System (ADS)

    Huang, Ou

    This study developed a geostatistical method to determine the required extent of terrain corrections for gravity gradients under the criterion of different applications. We present the different methods to compute the terrain corrections for gravity gradients for the case of ground and airborne gravity gradiometry. In order to verify our geostatistical method and study the required extent for different types of terrain, we also developed a method to simulate topography based on the covariance model. The required extents were determined from the variance of truncation error for one point, or furthermore from the variance of truncation error difference for a pair of points, and these variances were verified with that from the deterministic method. The extent of terrain correction was determined for ground gradiometry based on simulated, ultra-high resolution topography for very local application, and also was determined based on mountainous topography of large areas. For airborne gradiometry, we compute the terrain corrections and the required extent based on Air-FTG observations at Vinton Dome, LA and Parkfield, CA area; also they were verified with the results of Bell Geospace. Finally, from the mostly flat, medium rough and mountainous areas, an empirical relationship was developed which has the properties that the required extent has 4 times relationship corresponding to the amplitude of PSD has 100 times relationship between mountainous and mostly flat areas, and it can be interpolated for other types of topography from their geostatistics.

  3. Terrain profiling from Seasat altimetry

    NASA Technical Reports Server (NTRS)

    Brooks, R. L.

    1981-01-01

    To determine their applicability for terrain profiling, Seasat altimeter measurements were analyzed for the following geographic areas: (1) Andean salars of southern Bolivia; (2) Alaska; (3) south-central Arizona; (4) imperial Valley of California; (5) Yuma Valley of Arizona; and (6) Great Salt Lake Desert. Analysis of the data over all of these geographic areas shows that the satellite altimeter servo did not respond quickly enough to changing terrain features. However, it is demonstrated that retracking of the archived surface return waveforms yields surface elevations over smooth terrain accurate to + or - 1 m when correlated with large scale maps. The retracking algorithm used and its verification over the salars of southern Bolivia are described. Results are presented for each of the six geographic areas.

  4. Affects, agency, and self-regulation: complexity theory in the treatment of children with anxiety and disruptive behavior disorders.

    PubMed

    Tyson, Phyllis

    2005-01-01

    In an increasingly unsettled and violent world, with swelling numbers of children who are abused, abandoned, or neglected, emotionally if not physically, and an increasing population of aggressive preschool children with anxiety and disruptive behavior disorders who cannot be contained in ordinary settings, psychoanalysts can make a contribution. Early intervention is essential. In very early childhood, new procedural memories for interacting with others and for regulating affects can be formed more easily than they can ever be again. Intervention should aim toward helping the child develop a sense of agency, establish moral standards, assume self-responsibility, and attain the capacity for emotional regulation. The principles of complex dynamic systems can inform psychoanalytic treatment strategies, as demonstrated with five children whose cases are presented.

  5. Autonomous terrain parameter estimation for wheeled vehicles

    NASA Astrophysics Data System (ADS)

    Ray, Laura E.

    2008-04-01

    This paper reports a methodology for inferring terrain parameters from estimated terrain forces in order to allow wheeled autonomous vehicles to assess mobility in real-time. Terrain force estimation can be used to infer the ability to accelerate, climb, or tow a load independent of the underlying terrain model. When a terrain model is available, physical soil properties and stress distribution parameters that relate to mobility are inferred from vehicle-terrain forces using multiple-model estimation. The approach uses Bayesian statistics to select the most likely terrain parameters from a set of hypotheses, given estimated terrain forces. The hypotheses are based on the extensive literature of soil properties for soils with cohesions from 1 - 70 kPa. Terrain parameter estimation is subject to mathematical uniqueness of the net forces resulting from vehicle-terrain interaction for a given set of terrain parameters; uniqueness properties are characterized in the paper motivating the approach. Terrain force and parameter estimation requires proprioceptive sensors - accelerometers, rate gyros, wheel speeds, motor currents, and ground speed. Simulation results demonstrate efficacy of the method on three terrains - low cohesion sand, sandy loam, and high cohesion clay, with parameter convergence times as low as .02 sec. The method exhibits an ability to interpolate between hypotheses when no single hypothesis adequately characterizes the terrain.

  6. Iapetus Bright and Dark Terrains

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Saturn's outermost large moon, Iapetus, has a bright, heavily cratered icy terrain and a dark terrain, as shown in this Voyager 2 image taken on August 22, 1981. Amazingly, the dark material covers precisely the side of Iapetus that leads in the direction of orbital motion around Saturn (except for the poles), whereas the bright material occurs on the trailing hemisphere and at the poles. The bright terrain is made of dirty ice, and the dark terrain is surfaced by carbonaceous molecules, according to measurements made with Earth-based telescopes. Iapetus' dark hemisphere has been likened to tar or asphalt and is so dark that no details within this terrain were visible to Voyager 2. The bright icy hemisphere, likened to dirty snow, shows many large impact craters. The closest approach by Voyager 2 to Iapetus was a relatively distant 600,000 miles, so that our best images, such as this, have a resolution of about 12 miles. The dark material is made of organic substances, probably including poisonous cyano compounds such as frozen hydrogen cyanide polymers. Though we know a little about the dark terrain's chemical nature, we do not understand its origin. Two theories have been developed, but neither is fully satisfactory--(1) the dark material may be organic dust knocked off the small neighboring satellite Phoebe and 'painted' onto the leading side of Iapetus as the dust spirals toward Saturn and Iapetus hurtles through the tenuous dust cloud, or (2) the dark material may be made of icy-cold carbonaceous 'cryovolcanic' lavas that were erupted from Iapetus' interior and then blackened by solar radiation, charged particles, and cosmic rays. A determination of the actual cause, as well as discovery of any other geologic features smaller than 12 miles across, awaits the Cassini Saturn orbiter to arrive in 2004.

  7. Appraisal of digital terrain elevation data for low-altitude flight

    NASA Technical Reports Server (NTRS)

    Zelenka, Richard E.; Swenson, Harry N.

    1992-01-01

    The use of terrain elevation databases in advanced guidance and navigation systems has greatly expanded. However, the limitations and accuracies of these databases must be considered and established prior to safe system flight evaluation. A simple approach to quantify reasonable flight limits is presented and evaluated for a helicopter guidance system dependent on a terrain database. The flight test evaluated involved a helicopter equipped with a Global Positioning System (GPS) receiver and radar altimeter, and a ground station GPS receiver which provided improved helicopter positioning. The precision navigation and radar altimeter data was acquired while flying low-altitude missions in south-central Pennsylvania. The aircraft-determined terrain elevations were compared with the terrain predicted by the Defense Mapping Agency (DMA) Level 1 terrain elevation data for the same area. The results suggest a safe set clearance altitude of 220 ft for flight testing of a DMA-based guidance avionic in the same area.

  8. 77 FR 14584 - Eleventh Meeting: RTCA Special Committee 217, Joint With EUROCAE Working Group-44, Terrain and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-12

    ...@aviation-civile.grouv.fr , or telephone: 33-5-57- 92-57-81 or mobile, 33-5-57-92-55-55 1150. FOR FURTHER... Group--44, Terrain and Airport Mapping Databases AGENCY: Federal Aviation Administration (FAA), U.S... Working Group--44, Terrain and Airport Mapping Databases. SUMMARY: The FAA is issuing this notice...

  9. Remote sensing of earth terrain

    NASA Technical Reports Server (NTRS)

    Kong, Jin AU; Yueh, Herng-Aung; Shin, Robert T.

    1991-01-01

    Abstracts from 46 refereed journal and conference papers are presented for research on remote sensing of earth terrain. The topics covered related to remote sensing include the following: mathematical models, vegetation cover, sea ice, finite difference theory, electromagnetic waves, polarimetry, neural networks, random media, synthetic aperture radar, electromagnetic bias, and others.

  10. Terrain Perception for DEMO III

    NASA Technical Reports Server (NTRS)

    Manduchi, R.; Bellutta, P.; Matthies, L.; Owens, K.; Rankin, A.

    2000-01-01

    The Demo III program has as its primary focus the development of autonomous mobility for a small rugged cross country vehicle. In this paper we report recent progress on both stereo-based obstacle detection and terrain cover color-based classification.

  11. An automated system for terrain database construction

    NASA Technical Reports Server (NTRS)

    Johnson, L. F.; Fretz, R. K.; Logan, T. L.; Bryant, N. A.

    1987-01-01

    An automated Terrain Database Preparation System (TDPS) for the construction and editing of terrain databases used in computerized wargaming simulation exercises has been developed. The TDPS system operates under the TAE executive, and it integrates VICAR/IBIS image processing and Geographic Information System software with CAD/CAM data capture and editing capabilities. The terrain database includes such features as roads, rivers, vegetation, and terrain roughness.

  12. Guidelines for siting WECS relative to small-scale terrain features. Final report

    SciTech Connect

    Frost, W.; Shieh, C.F.

    1981-12-01

    Because real terrain is too complex and random to allow development of quantitative site selection data for specific applications, guidelines for siting wind energy conversion systems (WECS) relative to small-scale terrain features have been extracted from literature relative to analytical and experimental studies of fluid flow over geometries which represent idealized terrain features. These guidelines are presented in a format suitable for assessing the influence of small or microscale terrain features on a proposed wind turbine site. In organizing the available information, three categories of terrain were considered: (1) protrusions, topographical features that protrude well above the general level of their neighboring terrain; (2) depressions, areas such as valleys, canyons, or passes; and (3) complex terrain, so rugged or irregular that no well-defined protrusion or depression can be easily distinguished. The optimum site on a protrusion is always at the highest point. The smoother the peak of the protrusion and the more gentle the slopes on all sides the more optimum the site, providing the geometry and orientation of the depression are such that full advantage can be taken of existing strong valley winds or outflow. Where the terrain is very complex and tortuous, the highest point of the topography will be the optimum site.

  13. Geological terrains and crater frequencies on Ariel

    USGS Publications Warehouse

    Plescia, J.B.

    1987-01-01

    The southern hemisphere of Ariel, a satellite of Uranus, can be divided into several terrain types. Data on the size-frequency distribution of craters for those different terrain types indicate that these terrains formed over a relatively short period of time. Much information on Ariel's geological history can be gained from these data. ?? 1987 Nature Publishing Group.

  14. Revolutionary High Mobility Rovers for Rugged Terrain

    NASA Astrophysics Data System (ADS)

    Clark, P. E.; Curtis, S. A.; Rilee, M. L.; Cheung, C. Y.; Wesenberg, R. P.; Dorband, J. E.; Lunsford, A. W.

    2006-05-01

    Reconfigurable architecture is essential in exploration because reaching features of the great potential interest, whether searching for life in volcanic terrain or water in at the bottom of craters, will require crossing a wide range of terrains. Such areas of interest are largely inaccessible to permanently appendaged vehicles. For example, morphology and geochemistry of interior basins, walls, and ejecta blankets of volcanic or impact structures must all be studied to understand the nature of a geological event. One surface might be relatively flat and navigable, while another could be rough, variably sloping, broken, or dominated by unconsolidated debris. To be totally functional, structures must form pseudo-appendages varying in size, rate, and manner of deployment (gait). We have already prototyped a simple robotic walker from a single reconfigurable tetrahedron (with struts as sides and nodes as apices) capable of tumbling and are simulating and building a prototype of the more evolved 12Tetrahedral Walker (Autonomous Moon or Mars Investigator) which has interior nodes for payload, more continuous motion, and is commandable through a user friendly interface. We are currently developing a more differentiated architecture to form detachable, reconfigurable, reshapable linearly extendable bodies to act as manual assistant subsystems on rovers, with extensions terminating in a wider range of sensors. We are now simulating gaits for and will be building a prototype rover arm. Ultimately, complex continuous n-tetrahedral structures will have deployable outer skin, and even higher degrees of freedom. Tetrahedral rover advantages over traditional wheeled or tread robots are being demonstrated and include abilities to: 1) traverse terrain more rugged in terms of slope, roughness, and obstacle size; 2) precisely place and lower instruments into hard-to-reach crevices; 3) sample more locations per unit time; 4) conform to virtually any terrain; 5) avoid falling down or

  15. Remote sensing of earth terrain

    NASA Technical Reports Server (NTRS)

    Kong, J. A.

    1988-01-01

    A systematic approach for the identification of terrain media such as vegetation canopy, forest, and snow covered fields is developed using the optimum polarimetric classifier. The covariance matrices for the various terrain covers are computed from the theoretical models of random medium by evaluating the full polarimetric scattering matrix elements. The optimal classification scheme makes use of a quadratic distance measure and is applied to classify a vegetation canopy consisting of both trees and grass. Experimentally measured data are used to validate the classification scheme. Theoretical probability of classification error using the full polarimetric matrix are compared with classification based on single features including the phase difference between the VV and HH polarization returns. It is shown that the full polarimetric results are optimal and provide better classification performance than single feature measurements. A systematic approach is presented for obtaining the optimal polarimetric matched filter which produces maximum contrast between two scattering classes, each represented by its respective covariance matrix.

  16. Remote Sensing of Earth Terrain

    NASA Technical Reports Server (NTRS)

    Kong, J. A. (Principal Investigator)

    1985-01-01

    The objective of this research is to develop theoretical models that are useful and practical in the remote sensing of the Earth environment including the Earth terrain, the lower and the upper atmospheres. Various models applicable to the microwave remote sensing of vegetation, snow-ice, and atmospheric precipitation have been developed. Such studies shall be extended to the higher frequency range to unify the optical band and the microwave theoretical foundations. The study, which had an emphasis on vegetation canopy to include all terrain media, and the whole Earth environment will be extended. A data base will be developed to generate scene radiation characteristics which will benefit the studies of global inhabitability, meteorological applications, and crop yield.

  17. High-gain antenna & terrain

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Areas of rocky Martian terrain are seen in this image, taken by the Imager for Mars Pathfinder (IMP) on Sol 2. Portions of a lander petal and deflated airbag are at lower left. The dark disk at center is the high-gain antenna, and the silver cylindrical objects at upper right are part of the antenna's mechanism. An area of relatively smooth terrain is seen at upper right, which may offer clues to how this area was formed, and may be a future target for Sojourner's studies. The black area at lower right and small strip at top center is missing data.

    Mars Pathfinder was developed and managed by the Jet Propulsion Laboratory (JPL) for the National Aeronautics and Space Administration. The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.

  18. Segmentation of stereo terrain images

    NASA Astrophysics Data System (ADS)

    George, Debra A.; Privitera, Claudio M.; Blackmon, Theodore T.; Zbinden, Eric; Stark, Lawrence W.

    2000-06-01

    We have studied four approaches to segmentation of images: three automatic ones using image processing algorithms and a fourth approach, human manual segmentation. We were motivated toward helping with an important NASA Mars rover mission task -- replacing laborious manual path planning with automatic navigation of the rover on the Mars terrain. The goal of the automatic segmentations was to identify an obstacle map on the Mars terrain to enable automatic path planning for the rover. The automatic segmentation was first explored with two different segmentation methods: one based on pixel luminance, and the other based on pixel altitude generated through stereo image processing. The third automatic segmentation was achieved by combining these two types of image segmentation. Human manual segmentation of Martian terrain images was used for evaluating the effectiveness of the combined automatic segmentation as well as for determining how different humans segment the same images. Comparisons between two different segmentations, manual or automatic, were measured using a similarity metric, SAB. Based on this metric, the combined automatic segmentation did fairly well in agreeing with the manual segmentation. This was a demonstration of a positive step towards automatically creating the accurate obstacle maps necessary for automatic path planning and rover navigation.

  19. Automatic Computer Mapping of Terrain

    NASA Technical Reports Server (NTRS)

    Smedes, H. W.

    1971-01-01

    Computer processing of 17 wavelength bands of visible, reflective infrared, and thermal infrared scanner spectrometer data, and of three wavelength bands derived from color aerial film has resulted in successful automatic computer mapping of eight or more terrain classes in a Yellowstone National Park test site. The tests involved: (1) supervised and non-supervised computer programs; (2) special preprocessing of the scanner data to reduce computer processing time and cost, and improve the accuracy; and (3) studies of the effectiveness of the proposed Earth Resources Technology Satellite (ERTS) data channels in the automatic mapping of the same terrain, based on simulations, using the same set of scanner data. The following terrain classes have been mapped with greater than 80 percent accuracy in a 12-square-mile area with 1,800 feet of relief; (1) bedrock exposures, (2) vegetated rock rubble, (3) talus, (4) glacial kame meadow, (5) glacial till meadow, (6) forest, (7) bog, and (8) water. In addition, shadows of clouds and cliffs are depicted, but were greatly reduced by using preprocessing techniques.

  20. Hydrogeology of the Valles Marineris-Chaotic Terrain Transition Zone, Mars

    NASA Astrophysics Data System (ADS)

    Komatsu, G.; Rossi, A. P.; di Lorenzo, S.

    2004-03-01

    The Valles Marineris-chaotic terrain transition zone on Mars is rich in landforms indicative of past water and volcanic activities. Complex interactions of such activities are represented by features at Gangis Chasma and its surroundings.

  1. Simulated liquid water and visibility in stratiform boundary-layer clouds over sloping terrain

    SciTech Connect

    Tjernstroem, M. )

    1993-04-01

    The amount of liquid water in stratus clouds or fog is discussed from the point of view of estimating visibility variations in areas with complex terrain. The average vertical profile of liquid water from numerical simulations with a higher-order closure mesoscale model is examined, and runs with the model for moderately complex terrain are utilized to estimate the of low-level liquid water content variability and thus, indirectly, the variations in horizontal visibility along a slope. 37 refs., 11 figs.

  2. Groundwater flood hazards in lowland karst terrains

    NASA Astrophysics Data System (ADS)

    Naughton, Owen; McCormack, Ted

    2016-04-01

    The spatial and temporal complexity of flooding in karst terrains pose unique flood risk management challenges. Lowland karst landscapes can be particularly susceptible to groundwater flooding due to a combination of limited drainage capacity, shallow depth to groundwater and a high level of groundwater-surface water interactions. Historically the worst groundwater flooding to have occurred in the Rep. of Ireland has been centred on the Gort Lowlands, a karst catchment on the western coast of Ireland. Numerous notable flood events have been recorded throughout the 20th century, but flooding during the winters of 2009 and 2015 were the most severe on record, inundating an area in excess of 20km2 and causing widespread and prolonged disruption and damage to property and infrastructure. Effective flood risk management requires an understanding of the recharge, storage and transport mechanisms during flood conditions, but is often hampered by a lack of adequate data. Using information gathered from the 2009 and 2015 events, the main hydrological and geomorphological factors which influence flooding in this complex lowland karst groundwater system under are elucidated. Observed flood mechanisms included backwater flooding of sinks, overland flow caused by the overtopping of sink depressions, high water levels in turlough basins, and surface ponding in local epikarst watersheds. While targeted small-scale flood measures can locally reduce the flood risk associated with some mechanisms, they also have the potential to exacerbate flooding down-catchment and must be assessed in the context of overall catchment hydrology. This study addresses the need to improve our understanding of groundwater flooding in karst terrains, in order to ensure efficient flood prevention and mitigation in future and thus help achieve the aims of the EU Floods Directive.

  3. Overview of Venus geology: Preliminary description of terrain units for Venus global geological mapping

    NASA Technical Reports Server (NTRS)

    Saunders, R. Stephen; Stofan, Ellen R.; Plaut, Jeffrey J.; Michaels, Gregory A.

    1992-01-01

    Venus terrain units can be categorized on the basis of morphology, reflectivity, backscatter, roughness, and emissivity. Morphology can be inferred from Magellan left-looking nominal incidence angle image mosaics, right-looking coverage, and more limited left-looking stereo. The typical resolution is about 300 m down to about 120 m near periapsis in the cycle one nominal coverage. The scale of geologic mapping governs definition of mappable terrain units. Initial global mapping is being compiled at a scale of 1:50 million. At this scale, the smallest individual features that can be mapped are about 125 km. The categories of terrain types are plains, complex ridge terrain, features with morphology suggesting volcanic or volcano-tectonic origin, features interpreted to be tectonic in origin, crater units, and surficial units such as splotches and streaks. Brief descriptions of terrain units are provided.

  4. Terrain Portrayal for Synthetic Vision Systems Head-Down Displays Evaluation Results

    NASA Technical Reports Server (NTRS)

    Hughes, Monica F.; Glaab, Louis J.

    2007-01-01

    A critical component of SVS displays is the appropriate presentation of terrain to the pilot. At the time of this study, the relationship between the complexity of the terrain presentation and resulting enhancements of pilot SA and pilot performance had been largely undefined. The terrain portrayal for SVS head-down displays (TP-HDD) simulation examined the effects of two primary elements of terrain portrayal on the primary flight display (PFD): variations of digital elevation model (DEM) resolution and terrain texturing. Variations in DEM resolution ranged from sparsely spaced (30 arc-sec) to very closely spaced data (1 arc-sec). Variations in texture involved three primary methods: constant color, elevation-based generic, and photo-realistic, along with a secondary depth cue enhancer in the form of a fishnet grid overlay.

  5. Remote sensing of Earth terrain

    NASA Technical Reports Server (NTRS)

    Kong, Jin AU

    1987-01-01

    Earth terrain covers were modeled as random media characterized by different dielectric constants and correlation functions. In order to model sea ice with brine inclusions and vegetation with row structures, the random medium is assumed to be anisotropic. A three layer model is used to simulate a vegetation field or a snow covered ice field with the top layer being snow or leaves, the middle layer being ice or trunks, and the bottom layer being sea water or ground. The strong fluctuation theory with the distorted Born approximation is applied to the solution of the radar backscattering coefficients.

  6. Terrain synthesis from digital elevation models.

    PubMed

    Zhou, Howard; Sun, Jie; Turk, Greg; Rehg, James M

    2007-01-01

    In this paper, we present an example-based system for terrain synthesis. In our approach, patches from a sample terrain (represented by a height field) are used to generate a new terrain. The synthesis is guided by a user-sketched feature map that specifies where terrain features occur in the resulting synthetic terrain. Our system emphasizes large-scale curvilinear features (ridges and valleys) because such features are the dominant visual elements in most terrains. Both the example height field and user's sketch map are analyzed using a technique from the field of geomorphology. The system finds patches from the example data that match the features found in the user's sketch. Patches are joined together using graph cuts and Poisson editing. The order in which patches are placed in the synthesized terrain is determined by breadth-first traversal of a feature tree and this generates improved results over standard raster-scan placement orders. Our technique supports user-controlled terrain synthesis in a wide variety of styles, based upon the visual richness of real-world terrain data.

  7. Trial SNAPSHOT: measurements for terrain background characterization

    NASA Astrophysics Data System (ADS)

    Gilmore, Marilyn A.; Mitchell, Alistair A.; Bell, Christopher R.; Thomas, David J.; Evans, Roger

    2000-07-01

    The spatial and spectral characteristics of targets and backgrounds must be known and understood for a wide variety of reasons such as: synthetic scene simulation and validation; target description for modelling; in- service target material characterisation and background variability assessment. Without this information it will be impossible to design effective camouflage systems and to maximise the capabilities of new sensors. Laboratory measurements of background materials are insufficient to provide the data required. A series of trials are being undertaken in the UK to quantify both diurnal and seasonal changes of a terrain background, as well as the statistical variability within a scene. These trials are part of a collaborative effort between the Defence Evaluation and Research Agency (UK), Defence Clothing and Textile Agency (UK) and the T.A.C.O.M., USA). Data are being gathered at a single site consisting primarily of south facing mixed coniferous and deciduous woodland, but also containing uncultivated grassland and tracks. Ideally each point in the scene needs to be characterized at all relevant wavelengths but his is unrealistic. In addition there are a number of important environmental variables that are required. The goal of the measurement programme is to acquire data across the spectrum from 0.4 - 14 microns. Sensors used to include visible band imaging spectroradiometers, telespectroradiometers (visual, NIR, SWIR and LWIR), calibrate colour cameras, broad band SWIR and LWIR imagers and contact reflectance measurement equipment. Targets consist of painted panels with known material properties and a wheeled vehicle, which is in some cases covered with camouflage netting. Measurements have bene made of the background with and without the man- made objects present. This paper will review the results to date and present an analysis of the spectral characteristics fo different surfaces. In addition some consideration will be given to the implications of

  8. Topological Landscapes: A Terrain Metaphor for ScientificData

    SciTech Connect

    Weber, Gunther H.; Bremer, Peer-Timo; Pascucci, Valerio

    2007-08-01

    Scientific visualization and illustration tools are designed to help people understand the structure and complexity of scientific data with images that are as informative and intuitive as possible. In this context, the use of metaphors plays an important role, since they make complex information easily accessible by using commonly known concepts. In this paper we propose a new metaphor, called 'Topological Landscapes', which facilitates understanding the topological structure of scalar functions. The basic idea is to construct a terrain with the same topology as a given dataset and to display the terrain as an easily understood representation of the actual input data. In this projection from an n-dimensional scalar function to a two-dimensional (2D) model we preserve function values of critical points, the persistence (function span) of topological features, and one possible additional metric property (in our examples volume). By displaying this topologically equivalent landscape together with the original data we harness the natural human proficiency in understanding terrain topography and make complex topological information easily accessible.

  9. Evaluating planetary digital terrain models-The HRSC DTM test

    USGS Publications Warehouse

    Heipke, C.; Oberst, J.; Albertz, J.; Attwenger, M.; Dorninger, P.; Dorrer, E.; Ewe, M.; Gehrke, S.; Gwinner, K.; Hirschmuller, H.; Kim, J.R.; Kirk, R.L.; Mayer, H.; Muller, Jan-Peter; Rengarajan, R.; Rentsch, M.; Schmidt, R.; Scholten, F.; Shan, J.; Spiegel, M.; Wahlisch, M.; Neukum, G.

    2007-01-01

    The High Resolution Stereo Camera (HRSC) has been orbiting the planet Mars since January 2004 onboard the European Space Agency (ESA) Mars Express mission and delivers imagery which is being used for topographic mapping of the planet. The HRSC team has conducted a systematic inter-comparison of different alternatives for the production of high resolution digital terrain models (DTMs) from the multi look HRSC push broom imagery. Based on carefully chosen test sites the test participants have produced DTMs which have been subsequently analysed in a quantitative and a qualitative manner. This paper reports on the results obtained in this test. ?? 2007 Elsevier Ltd. All rights reserved.

  10. Remote sensing of Earth terrain

    NASA Technical Reports Server (NTRS)

    Kong, J. A.

    1992-01-01

    Research findings are summarized for projects dealing with the following: application of theoretical models to active and passive remote sensing of saline ice; radiative transfer theory for polarimetric remote sensing of pine forest; scattering of electromagnetic waves from a dense medium consisting of correlated Mie scatterers with size distribution and applications to dry snow; variance of phase fluctuations of waves propagating through a random medium; theoretical modeling for passive microwave remote sensing of earth terrain; polarimetric signatures of a canopy of dielectric cylinders based on first and second order vector radiative transfer theory; branching model for vegetation; polarimetric passive remote sensing of periodic surfaces; composite volume and surface scattering model; and radar image classification.

  11. Remote sensing of Earth terrain

    NASA Technical Reports Server (NTRS)

    Kong, J. A.

    1993-01-01

    Progress report on remote sensing of Earth terrain covering the period from Jan. to June 1993 is presented. Areas of research include: radiative transfer model for active and passive remote sensing of vegetation canopy; polarimetric thermal emission from rough ocean surfaces; polarimetric passive remote sensing of ocean wind vectors; polarimetric thermal emission from periodic water surfaces; layer model with tandom spheriodal scatterers for remote sensing of vegetation canopy; application of theoretical models to active and passive remote sensing of saline ice; radiative transfer theory for polarimetric remote sensing of pine forest; scattering of electromagnetic waves from a dense medium consisting of correlated mie scatterers with size distributions and applications to dry snow; variance of phase fluctuations of waves propagating through a random medium; polarimetric signatures of a canopy of dielectric cylinders based on first and second order vector radiative transfer theory; branching model for vegetation; polarimetric passive remote sensing of periodic surfaces; composite volume and surface scattering model; and radar image classification.

  12. Photometric Characteristics of Lunar Terrains

    NASA Astrophysics Data System (ADS)

    Sato, Hiroyuki; Hapke, Bruce W.; Denevi, Brett W.; Robinson, Mark

    2016-10-01

    The photometric properties of the lunar depend on albedo, surface roughness, porosity, and the internal/external structure of particles. Hapke parameter maps derived using a bidirectional reflectance model [Hapke, 2012] from Lunar Reconnaissance Orbiter Camera (LROC) Wide Angle Camera (WAC) images demonstrated the spatial and spectral variation of the photometric properties of the Moon [Sato et al., 2014]. Using the same methodology, here we present the photometric characteristics of typical lunar terrains, which were not systematically analyzed in the previous study.We selected five representative terrain types: mare, highland, swirls, and two Copernican (fresh) crater ejecta (one mare and one highlands example). As for the datasets, we used ~39 months of WAC repeated observations, and for each image pixel, we computed latitude, longitude, incidence, emission, and phase angles using the WAC GLD100 stereo DTM [Scholten et al., 2012]. To obtain similar phase and incidence angle ranges, all sampling sites are near the equator and in the vicinity of Reiner Gamma. Three free Hapke parameters (single scattering albedo: w, HG2 phase function parameter: c, and angular width of SHOE: hs) were then calculated for the seven bands (321-689 nm). The remaining parameters were fixed by simplifying the model [Sato et al., 2014].The highlands, highland ejecta, and swirl (Reiner Gamma) showed clearly higher w than the mare and mare ejecta. The derived c values were lower (less backscattering) for the swirl and higher (more backscattering) for the highlands (and ejecta) relative to the other sites. Forward scattering materials such as unconsolidated transparent crystalline materials might be relatively enriched in the swirl. In the highlands, anorthositic agglutinates with dense internal scattering could be responsible for the strong backscattering. The mare and mare ejecta showed continuously decreasing c from UV to visible wavelengths. This might be caused by the FeO-rich pyroxene

  13. A multidisciplinary approach to providing care to adolescents with spinal cord trauma resulting from all-terrain vehicle accidents.

    PubMed

    Rhodes, Leslie N; Weatherford, Blakely; Locke, Lindsey N; Chung, Hoi Sing; Tidwell, Chrisla; Paton, Elizabeth; Lee, Shirleatha

    2015-01-01

    All-terrain vehicle accidents that affect the spine can lead to complex injuries in adolescents. This requires that many subspecialties work together on a multidisciplinary team to improve patient outcomes. Our case presentation will examine the multidisciplinary approach to care required for an 11-year-old adolescent involved in an all-terrain vehicle accident that resulted in traumatic spinal cord injury.

  14. Preliminary design of a terrain recognition system.

    PubMed

    Zhang, Fan; Fang, Zheng; Liu, Ming; Huang, He

    2011-01-01

    This paper aims to design a wearable terrain recognition system, which might assist the control of powered artificial prosthetic legs. A laser distance sensor and inertial measurement unit (TMU) sensors were mounted on human body. These sensors were used to identify the movement state of the user, reconstruct the geometry of the terrain in front of the user while walking, and recognize the type of terrain before the user stepped on it. Different sensor configurations were investigated and compared. The designed system was evaluated on one healthy human subject when walking on an obstacle course in the laboratory environment. The results showed that the reconstructed terrain height demonstrated clearer pattern difference among studied terrains when the laser was placed on the waist than that when the laser was mounted on the shank. The designed system with the laser on the waist accurately recognized 157 out of 160 tested terrain transitions, 300 ms-2870 ms before the user switched the negotiated terrains. These promising results demonstrated the potential application of the designed terrain recognition system to further improve the control of powered artificial legs.

  15. Geomorphological Mapping of Sputnik Planum and Surrounding Terrain on Pluto

    NASA Astrophysics Data System (ADS)

    White, O. L.; Stern, S. A.; Weaver, H. A., Jr.; Olkin, C.; Ennico Smith, K.; Young, L. A.; Moore, J. M.; Cheng, A. F.

    2015-12-01

    The New Horizons flyby of Pluto in July 2015 has provided the first few close-up images of the Kuiper belt object, which reveal it to have a highly diverse range of terrains, implying a complex geological history. The highest resolution images that have yet been returned are seven lossy 400 m/pixel frames that cover the majority of the prominent Plutonian feature informally named Sputnik Planum (all feature names are currently informal), and its surroundings. This resolution is sufficient to allow detailed geomorphological mapping of this area to commence. Lossless versions of all 15 frames that make up the mosaic will be returned in September 2015, and the map presented at AGU will incorporate the total area covered by these frames. Sputnik Planum, with an area of ~650,000 km2, is notable for its smooth appearance and apparent total lack of impact craters at 400 m/pixel resolution. The Planum actually displays a wide variety of textures across its expanse, which includes smooth and pitted plains to the south, polygonal terrain at its center (the polygons can reach tens of kilometers in size and are bounded by troughs that sometimes feature central ridges), and, to the north, darker polygonal terrain displaying patterns indicative of glacial flow. Within these plains there exist several well-defined outcrops of a mottled, light/dark unit that reach from several to tens of kilometers across. Separating Sputnik Planum from the dark, cratered equatorial terrain of Cthulhu Regio on its south-western margin is a unit of chaotically arranged mountains; similar mountainous units exist on the south and western margins. The northern margin is bounded by rugged, hilly, cratered terrain into which ice of Sputnik Planum appears to be intruding in places. Terrain of similar relief exists to the east, but is much brighter than that to the north. The southernmost extent of the mosaic features a unit of rough, undulating terrain that displays very few impact craters at 400 m

  16. Geomorphological Mapping of Sputnik Planum and Surrounding Terrain on Pluto

    NASA Astrophysics Data System (ADS)

    White, Oliver; Stern, Alan; Weaver, Hal; Olkin, Cathy; Ennico, Kimberly; Young, Leslie; Moore, Jeff

    2015-11-01

    The New Horizons flyby of Pluto in July 2015 has provided the first few close-up images of the Kuiper belt object, which reveal it to have a highly diverse range of terrains, implying a complex geological history. The highest resolution images that have yet been returned are seven lossy 400 m/pixel frames that cover the majority of the prominent Plutonian feature informally named Sputnik Planum (all feature names are currently informal), and its surroundings. This resolution is sufficient to allow detailed geomorphological mapping of this area to commence. Lossless versions of all 15 frames that make up the mosaic will be returned in September 2015, and the map presented at DPS will incorporate the total area covered by these frames.Sputnik Planum, with an area of ~650,000 km2, is notable for its smooth appearance and apparent total lack of impact craters at 400 m/pixel resolution. The Planum actually displays a wide variety of textures across its expanse, which includes smooth and pitted plains to the south, polygonal terrain at its center (the polygons can reach tens of kilometers in size and are bounded by troughs that sometimes feature central ridges), and, to the north, darker polygonal terrain displaying patterns indicative of glacial flow. Within these plains there exist several well-defined outcrops of a mottled, light/dark unit that reach from several to tens of kilometers across. Separating Sputnik Planum from the dark, cratered equatorial terrain of Cthulhu Regio on its south-western margin is a unit of chaotically arranged mountains (Hillary Montes); similar mountainous units exist on the south and western margins. The northern margin is bounded by rugged, hilly, cratered terrain (Cousteau Rupes) into which ice of Sputnik Planum appears to be intruding in places. Terrain of similar relief exists to the east, but is much brighter than that to the north. The southernmost extent of the mosaic features a unit of rough, undulating terrain (Pandemonium Dorsa

  17. Convective boundary layer heights over mountainous terrain – A review of concepts –

    NASA Astrophysics Data System (ADS)

    De Wekker, Stephan; Kossmann, Meinolf

    2015-12-01

    Mountainous terrain exerts an important influence on the Earth's atmosphere and affects atmospheric transport and mixing at a wide range of temporal and spatial scales. The vertical scale of this transport and mixing is determined by the height of the atmospheric boundary layer, which is therefore an important parameter in air pollution studies, weather forecasting, climate modeling, and many other applications. It is recognized that the spatio-temporal structure of the daytime convective boundary layer (CBL) height is strongly modified and more complex in hilly and mountainous terrain compared to flat terrain. While the CBL over flat terrain is mostly dominated by turbulent convection, advection from multi-scale thermally driven flows plays an important role for the CBL evolution over mountainous terrain. However, detailed observations of the CBL structure and understanding of the underlying processes are still limited. Characteristics of CBL heights in mountainous terrain are reviewed for dry, convective conditions. CBLs in valleys and basins, where hazardous accumulation of pollutants is of particular concern, are relatively well-understood compared to CBLs over slopes, ridges, or mountain peaks. Interests in the initiation of shallow and deep convection, and of budgets and long-range transport of air pollutants and trace gases, have triggered some recent studies on terrain induced exchange processes between the CBL and the overlying atmosphere. These studies have helped to gain more insight into CBL structure over complex mountainous terrain, but also show that the universal definition of CBL height over mountains remains an unresolved issue. The review summarizes the progress that has been made in documenting and understanding spatio-temporal behavior of CBL heights in mountainous terrain and concludes with a discussion of open research questions and opportunities for future research.

  18. Convective boundary layer heights over mountainous terrain - A review of concepts -

    NASA Astrophysics Data System (ADS)

    De Wekker, Stephan; Kossmann, Meinolf

    2015-12-01

    Mountainous terrain exerts an important influence on the Earth's atmosphere and affects atmospheric transport and mixing at a wide range of temporal and spatial scales. The vertical scale of this transport and mixing is determined by the height of the atmospheric boundary layer, which is therefore an important parameter in air pollution studies, weather forecasting, climate modeling, and many other applications. It is recognized that the spatio-temporal structure of the daytime convective boundary layer (CBL) height is strongly modified and more complex in hilly and mountainous terrain compared to flat terrain. While the CBL over flat terrain is mostly dominated by turbulent convection, advection from multi-scale thermally driven flows plays an important role for the CBL evolution over mountainous terrain. However, detailed observations of the CBL structure and understanding of the underlying processes are still limited. Characteristics of CBL heights in mountainous terrain are reviewed for dry, convective conditions. CBLs in valleys and basins, where hazardous accumulation of pollutants is of particular concern, are relatively well-understood compared to CBLs over slopes, ridges, or mountain peaks. Interests in the initiation of shallow and deep convection, and of budgets and long-range transport of air pollutants and trace gases, have triggered some recent studies on terrain induced exchange processes between the CBL and the overlying atmosphere. These studies have helped to gain more insight into CBL structure over complex mountainous terrain, but also show that the universal definition of CBL height over mountains remains an unresolved issue. The review summarizes the progress that has been made in documenting and understanding spatio-temporal behavior of CBL heights in mountainous terrain and concludes with a discussion of open research questions and opportunities for future research.

  19. Towards terrain interaction prediction for bioinspired planetary exploration rovers.

    PubMed

    Yeomans, Brian; Saaj, Chakravathini M

    2014-03-01

    Deployment of a small legged vehicle to extend the reach of future planetary exploration missions is an attractive possibility but little is known about the behaviour of a walking rover on deformable planetary terrain. This paper applies ideas from the developing study of granular materials together with a detailed characterization of the sinkage process to propose and validate a combined model of terrain interaction based on an understanding of the physics and micro mechanics at the granular level. Whilst the model reflects the complexity of interactions expected from a walking rover, common themes emerge which enable the model to be streamlined to the extent that a simple mathematical representation is possible without resorting to numerical methods. Bespoke testing and analysis tools are described which reveal some unexpected conclusions and point the way towards intelligent control and foot geometry techniques to improve thrust generation.

  20. Axel Robotic Platform for Crater and Extreme Terrain Exploration

    NASA Technical Reports Server (NTRS)

    Nesnas, Issa A.; Matthews, Jaret B.; Edlund, Jeffrey A.; Burdick, Joel W.; Abad-Manterola, Pablo

    2012-01-01

    To be able to conduct science investigations on highly sloped and challenging terrains, it is necessary to deploy science payloads to such locations and collect and process in situ samples. A tethered robotic platform has been developed that is capable of exploring very challenging terrain. The Axel rover is a symmetrical rover that is minimally actuated, can traverse arbitrary paths, and operate upside-down or right-side up. It can be deployed from a larger platform (rover, lander, or aerobot) or from a dual Axel configuration. Axel carries and manages its own tether, reducing damage to the tether during operations. Fundamentally, Axel is a two-wheeled rover with a symmetric body and a trailing link. Because the primary goal is minimal complexity, this version of the Axel rover uses only four primary actuators to control its wheels, tether, and a trailing link. A fifth actuator is used for level winding of tether onto Axel s spool.

  1. Terrain identification for RHex-type robots

    NASA Astrophysics Data System (ADS)

    Ordonez, Camilo; Shill, Jacob; Johnson, Aaron; Clark, Jonathan; Collins, Emmanuel

    2013-05-01

    Terrain identification is a key enabling ability for generating terrain adaptive behaviors that assist both robot planning and motor control. This paper considers running legged robots from the RHex family) which the military plans to use in the field to assist troops in reconnaissance tasks. Important terrain adaptive behaviors include the selection of gaits) modulation of leg stiffness) and alteration of steering control laws that minimize slippage) maximize speed and/or reduce energy consumption. These terrain adaptive behaviors can be enabled by a terrain identification methodology that combines proprioceptive sensors already available in RHex-type robots. The proposed classification approach is based on the characteristic frequency signatures of data from leg observers) which combine current sensing with a dynamic model of the leg motion. The paper analyzes the classification accuracy obtained using both a single leg and groups of legs (through a voting scheme) on different terrains such as vinyl) asphalt) grass) and pebbles. Additionally) it presents a terrain classifier that works across various gait speeds and in fact almost as good as an overly specialized classifier.

  2. Terrain classification maps of Yellowstone National Park

    NASA Technical Reports Server (NTRS)

    Thomson, F. J.; Roller, N. E. G.

    1973-01-01

    A cooperative ERTS-1 investigation involving U. S. Geological Survey, National Park Service, and Environmental Research Institure of Michigan (ERIM) personnel has as its goal the preparation of terrain classification maps for the entire Yellowstone National Park. Excellent coverage of the park was obtained on 6 August 1972 (frame 1015-17404). Preliminary terrain classification maps have been prepared at ERIM by applying multispectral pattern recognition techniques to ERTS-MSS digital taped data. The color coded terrain maps are presented and discussed. The discussion includes qualitative and quantitative accuracy estimates and discussion of processing techniques.

  3. Automated basin delineation from digital terrain data

    NASA Technical Reports Server (NTRS)

    Marks, D.; Dozier, J.; Frew, J.

    1983-01-01

    While digital terrain grids are now in wide use, accurate delineation of drainage basins from these data is difficult to efficiently automate. A recursive order N solution to this problem is presented. The algorithm is fast because no point in the basin is checked more than once, and no points outside the basin are considered. Two applications for terrain analysis and one for remote sensing are given to illustrate the method, on a basin with high relief in the Sierra Nevada. This technique for automated basin delineation will enhance the utility of digital terrain analysis for hydrologic modeling and remote sensing.

  4. Karst on Mars? The thumbprint terrain

    NASA Technical Reports Server (NTRS)

    Schaefer, Martha W.

    1990-01-01

    The nature of the 'thumbprint' terrain noted by Guest et al. (1977) in high-resolution Viking Orbiter photographs of the northern plains of Mars is considered in light of plausible terrestrial analogs. At least some portion of such terrain may be due to differential solution of large carbonate deposits located in low-lying areas; comparative morphology may therefore indicate it to be an analog of the arid karst of Australia's Nullabor Plain, provided that groundwater flow was available during the terrain's formative period on Mars.

  5. Remote sensing of earth terrain

    NASA Technical Reports Server (NTRS)

    Kong, J. A.

    1985-01-01

    Progress on the investigation of the anisotropy of the terrain media, such as vegetation canopy and sea ice, and the study of the fluctuation-dissipation theorem in conjunction with the application of strong fluctuation theory for passive remote sensing of snowpacks is reported. The Feynman diagrammatic technique is used to derive the Dyson equation for the mean field and the Bethe-Salpeter equation for the correlation or the covariance of the field for electromagnetic wave propagation and scattering in an anisotropic random medium. With the random permittivity expressed in a general form, the bilocal and the nonlinear approximations are employed to solve the Dyson equation and the ladder approximation to the Bethe-Salpeter equation. The mean dyadic Green's function for a two layer anisotropic random medium with arbitrary three dimensional correlation function was investigated with the zeroth-order solutions to the Dyson equation under the four characteristic waves associated with the coherent vector fields propagating in an anisotropic random medium layer, which are the ordinary and extraordinary waves with upward and downward propagating vectors.

  6. Enigmatic Terrain of Elysium Planitia

    NASA Technical Reports Server (NTRS)

    2002-01-01

    [figure removed for brevity, see original site] (Released 1 August 2002) The lowland plains of Elysium Planitia contains a terrain that puzzles Mars scientists. The most intriguing and debatable landforms in the region are the plates and ridges seen through out most of this image. The plates can be up to 7 km diameter and appear to have been rafted apart. The plates can be 'jigsaw fitted' back in place. Various investigators have attributed the morphology of the plains material located on the floor of the Elysium basin to a wide range of geologic processes/landforms. Some researchers think that the plains are composed of low-viscosity flood lavas, while others argue for a fluvial origin (dried remnants of hyperconcentrated floods or mudflows). The plains surface exhibits a 'crusty' appearance that some researchers have attributed to crusted over flood lavas and pressure ridges. However, dried mudflows can exhibit the same type of texture. The debate continues. Numerous small dark haloed craters and a buried 1 km diameter crater can also be seen in the upper third of the image. Near the bottom of the image older cratered highlands and plains are visible as are the margins of the younger platy material.

  7. Cooperative operations in urban terrain (COUNTER)

    NASA Astrophysics Data System (ADS)

    Gross, David; Rasmussen, Steve; Chandler, Phil; Feitshans, Greg

    2006-05-01

    The Air Force Research Laboratory (AFRL) has an ongoing investigation to evaluate the behavior of Small Unmanned Aerial Vehicles (SAVs) and Micro Aerial Vehicles (MAVs) flying through an urban setting. This research is being conducted through the Cooperative Operations in UrbaN TERrain (COUNTER) 6.2 research and flight demonstration program. COUNTER is a theoretical and experimental program to develop the technology needed to integrate a single SAV, four MAVs, and a human operator for persistent intelligence, reconnaissance and surveillance for obscured targets in an urban environment. The research involves development of six-degree-of-freedom models for integration into simulations, modeling and integration of wind data for complex urban flows, cooperative control task assignment and path planning algorithms, video tracking and obstacle avoidance algorithms, and an Operator Vehicle Interface (OVI) system. The COUNTER concept and the contributing technologies will be proven via a series of flight tests and system demonstrations. The first of six planned COUNTER flight demonstrations occurred in July of 2005. This demonstration focused on the simultaneous flight operations of both the SAV and the MAV while displaying their respective telemetry data on a common ground station (OVI). Current efforts are focused on developing the architecture for the Cooperative Control Algorithm. In FY 2006, the COUNTER program will demonstrate the ability to pass vehicle waypoints from the OVI station to the SAV and MAV vehicles. In FY 2007, COUNTER will focus on solutions to the optical target tracking (SAV) and obstacle avoidance (MAV) issues.

  8. An ice-rich flow origin for the banded terrain in the Hellas basin, Mars

    NASA Astrophysics Data System (ADS)

    Diot, X.; El-Maarry, M. R.; Guallini, L.; Schlunegger, F.; Norton, K. P.; Thomas, N.; Sutton, S.; Grindrod, P. M.

    2015-12-01

    The interior of Hellas Basin displays a complex landscape and a variety of geomorphological domains. One of these domains, the enigmatic banded terrain covers much of the northwestern part of the basin. We use high-resolution (Context Camera and High-Resolution Imaging Science Experiment) Digital Terrain Models to show that most of the complex viscous flowing behavior exhibited by the banded terrain is controlled by topography and flow-like interactions between neighboring banded terrain. Furthermore, the interior of the basin hosts several landforms suggestive of the presence of near-surface ice, which include polygonal patterns with elongated pits, scalloped depressions, isolated mounds, and collapse structures. We suggest that thermal contraction cracking and sublimation of near-surface ice are responsible for the formation and the development of most of the ice-related landforms documented in Hellas. The relatively pristine form, lack of superposed craters, and strong association with the banded terrain, suggest an Amazonian (<3 Ga) age of formation for these landforms. Finally, relatively high surface pressures (above the triple point of water) expected in Hellas and summertime temperatures often exceeding the melting point of water ice suggest that the basin may have recorded relatively "temperate" climatic conditions compared to other places on Mars. Therefore, the potentially ice-rich banded terrain may have deformed with lower viscosity and stresses compared to other locations on Mars, which may account for its unique morphology.

  9. Photometric Properties of Thermally Anomalous Terrain on Icy Saturnian Satellites

    NASA Astrophysics Data System (ADS)

    Annex, Andrew; Verbiscer, A. J.; Helfenstein, P.; Howett, C.; Schenk, P.

    2013-10-01

    Spectral maps of thermal emission from Mimas obtained by Cassini’s Composite InfraRed Spectrometer (CIRS) show that a V-shaped boundary, centered at 0° N and 180° W, divides relatively warm daytime temperatures from an anomalously cooler region at low to mid-latitudes on the leading hemisphere (Howett et al. 2011 Icarus 216, 211). This cooler region is also warmer at night, indicating that it has high thermal inertia, and also coincides in shape and location with that of high-energy electron deposition from Saturn’s magnetosphere (Roussos et al. 2007 JGR 112, A06214; Schenk et al. 2011 Icarus 211, 740). Global IR/UV color ratio maps assembled from Cassini Imaging Science Subsystem (ISS) images revealed a lens-shaped region of relatively blue terrain centered on the leading hemisphere (Schenk et al. 2011, Icarus). The area with low IR/UV ratio also coincides in shape and location with the region of high thermal inertia. A preliminary photometric analysis of Cassini ISS CL1 CL2 filter (centered at 611 nm) images using the Hapke (2008) model suggests that the high thermal inertia region on Mimas is rougher and more strongly backscattering than terrain with lower thermal inertia. Particles on the surface of the thermally anomalous terrain may have a more complex microtexture due to the high-energy electron bombardment. This work is supported by the NASA Cassini Data Analysis Program.

  10. Terrain discovery and navigation of a multi-articulated linear robot using map-seeking circuits

    NASA Astrophysics Data System (ADS)

    Snider, Ross K.; Arathorn, David W.

    2006-05-01

    A significant challenge in robotics is providing a robot with the ability to sense its environment and then autonomously move while accommodating obstacles. The DARPA Grand Challenge, one of the most visible examples, set the goal of driving a vehicle autonomously for over a hundred miles avoiding obstacles along a predetermined path. Map-Seeking Circuits have shown their biomimetic capability in both vision and inverse kinematics and here we demonstrate their potential usefulness for intelligent exploration of unknown terrain using a multi-articulated linear robot. A robot that could handle any degree of terrain complexity would be useful for exploring inaccessible crowded spaces such as rubble piles in emergency situations, patrolling/intelligence gathering in tough terrain, tunnel exploration, and possibly even planetary exploration. Here we simulate autonomous exploratory navigation by an interaction of terrain discovery using the multi-articulated linear robot to build a local terrain map and exploitation of that growing terrain map to solve the propulsion problem of the robot.

  11. Terrain coverage of an unknown room by an autonomous mobile robot

    SciTech Connect

    VanderHeide, J.R.

    1995-12-05

    Terrain coverage problems are nearly as old as mankind: they were necessary early in our history for basic activities such as finding food and other necessities. As our societies and their associated machineries have grown more complex, we have not outgrown the need for this primitive skill. It is still used on a small scale for cleaning tasks and on a large scale for {open_quotes}search and report{close_quotes} missions of various kinds. The motivation for automating this process may not lie in the novelty of anything we might gain as an end product, but in freedom from something which we as humans find tedious, time-consuming and sometimes dangerous. Here we consider autonomous coverage of a terrain, typically indoor rooms, by a mobile robot that has no a priori model of the terrain. In evaluating its surroundings, the robot employs only inexpensive and commercially available ultrasonic and infrared sensors. The proposed solution is a basic step - a proof of principle - that can contribute to robots capable of autonomously performing tasks such as vacuum cleaning, mopping, radiation scanning, etc. The area of automatic terrain coverage and the closely related problem of terrain model acquisition have been studied both analytically and experimentally. Compared to the existing works, the following are three major distinguishing aspects of our study: (1) the theory is actually applied to an existing robot, (2) the robot has no a priori knowledge of the terrain, and (3) the robot can be realized relatively inexpensively.

  12. Artificial intelligence technologies applied to terrain analysis

    SciTech Connect

    Wright, J.C. ); Powell, D.R. )

    1990-01-01

    The US Army Training and Doctrine Command is currently developing, in cooperation with Los Alamos National Laboratory, a Corps level combat simulation to support military analytical studies. This model emphasizes high resolution modeling of the command and control processes, with particular attention to architectural considerations that enable extension of the model. A planned future extension is the inclusion of an computer based planning capability for command echelons that can be dynamical invoked during the execution of then model. Command and control is the process through which the activities of military forces are directed, coordinated, and controlled to achieve the stated mission. To perform command and control the commander must understand the mission, perform terrain analysis, understand his own situation and capabilities as well as the enemy situation and his probable actions. To support computer based planning, data structures must be available to support the computer's ability to understand'' the mission, terrain, own capabilities, and enemy situation. The availability of digitized terrain makes it feasible to apply artificial intelligence technologies to emulate the terrain analysis process, producing data structures for uses in planning. The work derived thus for to support the understanding of terrain is the topic of this paper. 13 refs., 5 figs., 6 tabs.

  13. Radar scattering statistics for digital terrain models

    NASA Astrophysics Data System (ADS)

    Wilson, Kelce; Patrick, Dale; Blair, James

    2005-05-01

    The statistic results for a digital terrain model are presented that closely match measurements for 77% of the 189 possible combinations of 7 radar bands, 3 polarizations, and 9 terrain types. The model produces realistic backscatter coefficient values for the scenarios over all incidence angles from normal to grazing. The generator was created using measured data sets reported in the Handbook of Radar Scattering Statistics for Terrain covering L, C, S, X, Ka, Ku, and W frequency bands; HH, HV, and VV polarizations; and soil and rock, shrub, tree, short vegetation, grass, dry snow, wet snow, road surface, and urban area terrain types. The first two statistical moments match published values precisely, and a Chi-Square histogram test failed to reject the generator at a 95% confidence level for the 146 terrain models implemented. A Sea State model provides the grazing angle extension for predictions beyond the available measurements. This work will contain a comprehensive set of plots of mean and standard deviation versus incidence angle.

  14. High performance robotic traverse of desert terrain.

    SciTech Connect

    Whittaker, William

    2004-09-01

    This report presents tentative innovations to enable unmanned vehicle guidance for a class of off-road traverse at sustained speeds greater than 30 miles per hour. Analyses and field trials suggest that even greater navigation speeds might be achieved. The performance calls for innovation in mapping, perception, planning and inertial-referenced stabilization of components, hosted aboard capable locomotion. The innovations are motivated by the challenge of autonomous ground vehicle traverse of 250 miles of desert terrain in less than 10 hours, averaging 30 miles per hour. GPS coverage is assumed to be available with localized blackouts. Terrain and vegetation are assumed to be akin to that of the Mojave Desert. This terrain is interlaced with networks of unimproved roads and trails, which are a key to achieving the high performance mapping, planning and navigation that is presented here.

  15. Large Terrain Modeling and Visualization for Planets

    NASA Technical Reports Server (NTRS)

    Myint, Steven; Jain, Abhinandan; Cameron, Jonathan; Lim, Christopher

    2011-01-01

    Physics-based simulations are actively used in the design, testing, and operations phases of surface and near-surface planetary space missions. One of the challenges in realtime simulations is the ability to handle large multi-resolution terrain data sets within models as well as for visualization. In this paper, we describe special techniques that we have developed for visualization, paging, and data storage for dealing with these large data sets. The visualization technique uses a real-time GPU-based continuous level-of-detail technique that delivers multiple frames a second performance even for planetary scale terrain model sizes.

  16. Tessera terrain: Characteristics and models of origin

    NASA Technical Reports Server (NTRS)

    Bindschadler, D. L.; Head, James W.

    1989-01-01

    Tessera terrain consists of complexly deformed regions characterized by sets of ridges and valleys that intersect at angles ranging from orthogonal to oblique, and were first viewed in Venera 15/16 SAR data. Tesserae cover more area (approx. 15 percent of the area north of 30 deg N) than any of the other tectonic units mapped from the Venera data and are strongly concentrated in the region between longitudes 0 deg E and 150 deg E. Tessera terrain is concentrated between a proposed center of crustal extension and divergence in Aphrodite and a region of intense deformation, crustal convergence, and orogenesis in western Ishtar Terra. Thus, the tectonic processes responsible for tesserae are an important part of Venus tectonics. As part of an effort to understand the formation and evolution of this unusual terrain type, the basic characteristics of the tesserae were compared to the predictions made by a number of tectonic models. The basic characteristics of tessera terrain are described and the models and some of their basic predictions are briefly discussed.

  17. Terrain Models in Field Geology Courses.

    ERIC Educational Resources Information Center

    Whittecar, G. Richard

    1984-01-01

    Describes a terrain model for geologic mapping which, when combined with exercises in rock description, Brunton compass manipulation, orienteering, and geologic report writing, allows students to refine skills needed for summer field camp. Advantages and limitations of the model and its use in a field course are also discussed. (BC)

  18. Terrain trafficability characterization with a mobile robot

    NASA Astrophysics Data System (ADS)

    Ojeda, Lauro; Borenstein, Johann; Witus, Gary

    2005-05-01

    Most research on off-road mobile robot sensing focuses on obstacle negotiation, path planning, and position estimation. These issues have conventionally been the foremost factors limiting the performance and speeds of mobile robots. Very little attention has been paid to date to the issue of terrain trafficability, that is, the terrain's ability to support vehicular traffic. Yet, trafficability is of great importance if mobile robots are to reach speeds that human-driven vehicles can reach on rugged terrain. For example, it is obvious that the maximal allowable speed for a turn is lower when driving over sand or wet grass than when driving on packed dirt or asphalt. This paper presents our work on automated real-time characterization of terrain with regard to trafficability for small mobile robots. The two proposed methods can be implemented on skid-steer mobile robots and possibly also on tracked mobile robots. The paper also presents experimental results for each of the two implemented methods.

  19. Processes Modifying Cratered Terrains on Pluto

    NASA Technical Reports Server (NTRS)

    Moore, J. M.

    2015-01-01

    The July encounter with Pluto by the New Horizons spacecraft permitted imaging of its cratered terrains with scales as high as approximately 100 m/pixel, and in stereo. In the initial download of images, acquired at 2.2 km/pixel, widely distributed impact craters up to 260 km diameter are seen in the near-encounter hemisphere. Many of the craters appear to be significantly degraded or infilled. Some craters appear partially destroyed, perhaps by erosion such as associated with the retreat of scarps. Bright ice-rich deposits highlight some crater rims and/or floors. While the cratered terrains identified in the initial downloaded images are generally seen on high-to-intermediate albedo surfaces, the dark equatorial terrain informally known as Cthulhu Regio is also densely cratered. We will explore the range of possible processes that might have operated (or still be operating) to modify the landscape from that of an ancient pristinely cratered state to the present terrains revealed in New Horizons images. The sequence, intensity, and type of processes that have modified ancient landscapes are, among other things, the record of climate and volatile evolution throughout much of the Pluto's existence. The deciphering of this record will be discussed. This work was supported by NASA's New Horizons project.

  20. AirMSPI PODEX Nicasio Terrain Images

    Atmospheric Science Data Center

    2013-12-12

    ... Images from the PODEX 2013 Campaign   Nicasio target (Nicasio, California) 02/03/2013 Terrain-projected   ... central observation tttt:                 Target name aaa:               Mean viewing angle (reported to the ...

  1. AirMSPI PODEX Yorkville Terrain Images

    Atmospheric Science Data Center

    2013-12-12

    ... Images from the PODEX 2013 Campaign   Yorkville target (Yorkville, California) 02/03/2013 Terrain-projected   ... central observation tttt:                 Target name aaa:               Mean viewing angle (reported to the ...

  2. AirMSPI PODEX Sonoma Terrain Images

    Atmospheric Science Data Center

    2013-12-12

    ... Images from the PODEX 2013 Campaign   Sonoma target (Sonoma, California) 02/03/2013 Terrain-projected   ... central observation tttt:                 Target name aaa:               Mean viewing angle (reported to the ...

  3. Scaling Terrain Attributes By Fractal Methods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Terrain attributes derived from grid digital elevation models (DEMs) are commonly used in distributed hydrologic models. However, many attribute estimations are biased by DEM grid cell size. For example, land surface slopes estimated from 30-m DEMs are, on average, less than slopes estimated from ...

  4. Visualization of Large Terrains Made Easy

    SciTech Connect

    Lindstrom, P; Pascucci, V

    2001-08-07

    We present an elegant and simple to implement framework for performing out-of-core visualization and view-dependent refinement of large terrain surfaces. Contrary to the recent trend of increasingly elaborate algorithms for large-scale terrain visualization, our algorithms and data structures have been designed with the primary goal of simplicity and efficiency of implementation. Our approach to managing large terrain data also departs from more conventional strategies based on data tiling. Rather than emphasizing how to segment and efficiently bring data in and out of memory, we focus on the manner in which the data is laid out to achieve good memory coherency for data accesses made in a top-down (coarse-to-fine) refinement of the terrain. We present and compare the results of using several different data indexing schemes, and propose a simple to compute index that yields substantial improvements in locality and speed over more commonly used data layouts. Our second contribution is a new and simple, yet easy to generalize method for view-dependent refinement. Similar to several published methods in this area, we use longest edge bisection in a top-down traversal of the mesh hierarchy to produce a continuous surface with subdivision connectivity. In tandem with the refinement, we perform view frustum culling and triangle stripping. These three components are done together in a single pass over the mesh. We show how this framework supports virtually any error metric, while still being highly memory and compute efficient.

  5. Photometric diversity of terrains on Triton

    NASA Technical Reports Server (NTRS)

    Hillier, J.; Veverka, J.; Helfenstein, P.; Lee, P.

    1994-01-01

    Voyager disk-resolved images of Triton in the violet (0.41 micrometers) and green (0.56 micrometer wavelengths have been analyzed to derive the photometric characteristics of terrains on Triton. Similar conclusions are found using two distinct but related definitions of photometric units, one based on color ratio and albedo properties (A. S. McEwen, 1990), the other on albedo and brightness ratios at different phase angles (P. Lee et al., 1992). A significant diversity of photometric behavior, much broader than that discovered so far on any other icy satellite, occurs among Triton's terrains. Remarkably, differences in photometric behavior do not correlate well with geologic terrain boundaries defined on the basis of surface morphology. This suggests that in most cases photometric properties on Triton are controlled by thin deposits superposed on underlying geologic units. Single scattering albedos are 0.98 or higher and asymmetry factors range from -0.35 to -0.45 for most units. The most distinct scattering behavior is exhibited by the reddish northern units already identified as the Anomalously Scattering Region (ASR), which scatters light almost isotropically with g = -0.04. In part due to the effects of Triton's clouds and haze, it is difficult to constrain the value of bar-theta, Hapke's macroscopic roughness parameter, precisely for Triton or to map differences in bar-theta among the different photometric terrains. However, our study shows that Triton must be relatively smooth, with bar-theta less than 15-20 degs and suggests that a value of 14 degs is appropriate. The differences in photometric characteristics lead to significantly different phase angle behavior for the various terrains. For example, a terrain (e.g., the ASR) that appears dark relative to another at low phase angles will reverse its contrast (become relatively brighter) at larger phase angles. The photometric parameters have been used to calculate hemispherical albedos for the units and to

  6. An experimental study of two-phase slug flow in hilly terrain pipelines

    SciTech Connect

    Zheng, G.H.; Brill, J.P.; Shoham, O.

    1995-11-01

    Experiments were conducted in a 76.2-mm diameter, 420-m long two-phase flow loop to study slug flow behavior in hilly terrain pipelines. Complex physical phenomena were observed, including generation of pseudoslugs at the horizontal/uphill elbow, variation of slug length along the pipeline, and persistent existence of slug flow in the downhill section.

  7. PROGRAM-ORIENTED INFORMATION--A MANAGEMENT SYSTEMS COMPLEX FOR STATE EDUCATION AGENCIES. PART I, ANALYSIS AND PROPOSALS. INTERIM REPORT ON A COLLABORATIVE PROJECT "TENTATIVE GUIDES FOR A STATE EDUCATION AGENCY FISCAL, PERSONNEL, AND PROGRAM INFORMATION SYSTEM."

    ERIC Educational Resources Information Center

    FRIEDMAN, BURTON DEAN; AND OTHERS

    THIS DOCUMENT IS THE RESULT OF A PROJECT TO CONCEIVE AND ESTABLISH AN INFORMATION SYSTEM FOR FINANCIAL, PERSONNEL, AND PROGRAM ACCOUNTING OF STATE EDUCATION AGENCIES' TOTAL INTERNAL OPERATION. SUCH SYSTEMS ARE DEEMED NECESSARY NOW THAT THE AGENCIES' OPERATIONS ARE STRONGLY AFFECTED BY FEDERAL PROGRAMS AND FUNDS AND ARE THUS A MATTER OF NATIONWIDE…

  8. Tessera terrain on Venus: Global characterization from Magellan data

    NASA Technical Reports Server (NTRS)

    Ivanov, Mikhail; Head, James W.

    1993-01-01

    Tessera terrain is characterized by relatively high elevations and complex tectonic patterns; analysis of Venera 15/16 data showed that large (up to thousands of km across) and small (up to hundreds of km across) occurrences of tesserae are widespread and non-randomly distributed and make up about 10-15 percent of the surface of Venus north of approximately 30 deg N. In a previous analysis, we used the Magellan Cycle 1 and 2 data to map the global distribution of tesserae on the basis of the following: (1) complex deformational patterns (two or more trends); (2) relatively high radar backscatter; and (3) relatively high elevation. Here we report on the quantitative aspects of tesserae areal, size, and shape distribution and on the characteristics and distribution of tesserae boundaries. Experiments on volcanic flooding of tessera and implications for tessera presence beneath the plains and analysis of the distribution of impact craters on tesserae and the plains are reported elsewhere.

  9. Subjective results of a simulator evaluation using synthetic terrain imagery presented on a helmet-mounted display

    NASA Astrophysics Data System (ADS)

    Rate, Christopher R.; Probert, Andrew; Wright, David; Corwin, William H.; Royer, Rick

    1994-06-01

    Combat mission scenarios require pilots to maneuver their aircraft over and around various terrain features at high speeds and low altitudes day, night, or in adverse meteorological conditions. While current systems (e.g., Night Vision Goggles and FLIR) provide some support for the pilot, they are not adequate in many weather conditions. However, the effects of adverse weather can be overcome using the U. S. Defense Mapping Agency's digital terrain elevation database to create a synthetic terrain image (STI). The concept of synthetically derived terrain imagery, projected as background on a Helmet-Mounted Display, was investigated in regards to its utility for enhancing pilot terrain awareness. An initial study using four Lockheed pilots and six USAF pilots was conducted to determine subjective preference of STI formats. A follow-on study, using two preferred formats, evaluated STI in a full-mission simulation environment. Six F-16 pilots completed a half day of training and a one day evaluation. Data was collected on missions involving low level navigation, followed by a laser guided bomb loft or offset roll- in dive bomb attack. Thirteen missions per pilot were completed including bomb runs using LANTIRN without STI. All the runs were at night with either 'poor' or 'good' FLIR conditions over rough or moderately rolling terrain. The evaluation indicated that pilots found STI to be useful and offered real-time support for low level navigation. Some problems still exist (e.g., field of view of HMD), which will be investigated in future studies.

  10. 47 CFR 1.959 - Computation of average terrain elevation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 1 2014-10-01 2014-10-01 false Computation of average terrain elevation. 1.959... Procedures § 1.959 Computation of average terrain elevation. Except as otherwise specified in § 90.309(a)(4) of this chapter, average terrain elevation must be calculated by computer using elevations from a...

  11. 47 CFR 1.959 - Computation of average terrain elevation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 1 2013-10-01 2013-10-01 false Computation of average terrain elevation. 1.959... Procedures § 1.959 Computation of average terrain elevation. Except as otherwise specified in § 90.309(a)(4) of this chapter, average terrain elevation must be calculated by computer using elevations from a...

  12. 47 CFR 1.959 - Computation of average terrain elevation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 1 2011-10-01 2011-10-01 false Computation of average terrain elevation. 1.959... of average terrain elevation. Except as otherwise specified in § 90.309(a)(4) of this chapter, average terrain elevation must be calculated by computer using elevations from a 30 second point or...

  13. 14 CFR 91.223 - Terrain awareness and warning system.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 2 2012-01-01 2012-01-01 false Terrain awareness and warning system. 91..., and Certificate Requirements § 91.223 Terrain awareness and warning system. (a) Airplanes manufactured... seat, unless that airplane is equipped with an approved terrain awareness and warning system that as...

  14. 41 CFR 101-45.004 - All terrain vehicles.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 41 Public Contracts and Property Management 2 2011-07-01 2007-07-01 true All terrain vehicles. 101-45.004 Section 101-45.004 Public Contracts and Property Management Federal Property Management... DESTRUCTION OF PERSONAL PROPERTY § 101-45.004 All terrain vehicles. (a) Three-wheeled all terrain...

  15. 47 CFR 80.759 - Average terrain elevation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Average terrain elevation. 80.759 Section 80... Average terrain elevation. (a)(1) Draw radials from the antenna site for each 45 degrees of azimuth...) Calculate the height above average terrain by averaging the values calculated for each radial....

  16. 47 CFR 80.759 - Average terrain elevation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Average terrain elevation. 80.759 Section 80... Average terrain elevation. (a)(1) Draw radials from the antenna site for each 45 degrees of azimuth...) Calculate the height above average terrain by averaging the values calculated for each radial....

  17. 41 CFR 101-45.004 - All terrain vehicles.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 41 Public Contracts and Property Management 2 2013-07-01 2012-07-01 true All terrain vehicles. 101-45.004 Section 101-45.004 Public Contracts and Property Management Federal Property Management... DESTRUCTION OF PERSONAL PROPERTY § 101-45.004 All terrain vehicles. (a) Three-wheeled all terrain...

  18. 14 CFR 93.311 - Minimum terrain clearance.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Minimum terrain clearance. 93.311 Section... of Grand Canyon National Park, AZ § 93.311 Minimum terrain clearance. Except in an emergency, when... a purpose listed in § 93.309(c), no person may operate an aircraft within 500 feet of any terrain...

  19. 14 CFR 93.311 - Minimum terrain clearance.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 2 2014-01-01 2014-01-01 false Minimum terrain clearance. 93.311 Section... of Grand Canyon National Park, AZ § 93.311 Minimum terrain clearance. Except in an emergency, when... a purpose listed in § 93.309(c), no person may operate an aircraft within 500 feet of any terrain...

  20. 47 CFR 1.959 - Computation of average terrain elevation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 1 2012-10-01 2012-10-01 false Computation of average terrain elevation. 1.959... Procedures § 1.959 Computation of average terrain elevation. Except as otherwise specified in § 90.309(a)(4) of this chapter, average terrain elevation must be calculated by computer using elevations from a...

  1. 47 CFR 80.759 - Average terrain elevation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Average terrain elevation. 80.759 Section 80... Average terrain elevation. (a)(1) Draw radials from the antenna site for each 45 degrees of azimuth...) Calculate the height above average terrain by averaging the values calculated for each radial....

  2. 47 CFR 80.759 - Average terrain elevation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Average terrain elevation. 80.759 Section 80... Average terrain elevation. (a)(1) Draw radials from the antenna site for each 45 degrees of azimuth...) Calculate the height above average terrain by averaging the values calculated for each radial....

  3. 14 CFR 93.311 - Minimum terrain clearance.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 2 2011-01-01 2011-01-01 false Minimum terrain clearance. 93.311 Section... of Grand Canyon National Park, AZ § 93.311 Minimum terrain clearance. Except in an emergency, when... a purpose listed in § 93.309(c), no person may operate an aircraft within 500 feet of any terrain...

  4. 14 CFR 91.223 - Terrain awareness and warning system.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 2 2013-01-01 2013-01-01 false Terrain awareness and warning system. 91..., and Certificate Requirements § 91.223 Terrain awareness and warning system. (a) Airplanes manufactured... seat, unless that airplane is equipped with an approved terrain awareness and warning system that as...

  5. 41 CFR 101-45.004 - All terrain vehicles.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 41 Public Contracts and Property Management 2 2014-07-01 2012-07-01 true All terrain vehicles. 101-45.004 Section 101-45.004 Public Contracts and Property Management Federal Property Management... DESTRUCTION OF PERSONAL PROPERTY § 101-45.004 All terrain vehicles. (a) Three-wheeled all terrain...

  6. 14 CFR 93.311 - Minimum terrain clearance.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 2 2012-01-01 2012-01-01 false Minimum terrain clearance. 93.311 Section... of Grand Canyon National Park, AZ § 93.311 Minimum terrain clearance. Except in an emergency, when... a purpose listed in § 93.309(c), no person may operate an aircraft within 500 feet of any terrain...

  7. 41 CFR 101-45.004 - All terrain vehicles.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 41 Public Contracts and Property Management 2 2010-07-01 2010-07-01 true All terrain vehicles. 101-45.004 Section 101-45.004 Public Contracts and Property Management Federal Property Management... DESTRUCTION OF PERSONAL PROPERTY § 101-45.004 All terrain vehicles. (a) Three-wheeled all terrain...

  8. 47 CFR 1.959 - Computation of average terrain elevation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Computation of average terrain elevation. 1.959... of average terrain elevation. Except as otherwise specified in § 90.309(a)(4) of this chapter, average terrain elevation must be calculated by computer using elevations from a 30 second point or...

  9. 14 CFR 93.311 - Minimum terrain clearance.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 2 2013-01-01 2013-01-01 false Minimum terrain clearance. 93.311 Section... of Grand Canyon National Park, AZ § 93.311 Minimum terrain clearance. Except in an emergency, when... a purpose listed in § 93.309(c), no person may operate an aircraft within 500 feet of any terrain...

  10. 41 CFR 101-45.004 - All terrain vehicles.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 41 Public Contracts and Property Management 2 2012-07-01 2012-07-01 false All terrain vehicles. 101-45.004 Section 101-45.004 Public Contracts and Property Management Federal Property Management... DESTRUCTION OF PERSONAL PROPERTY § 101-45.004 All terrain vehicles. (a) Three-wheeled all terrain...

  11. 14 CFR 91.223 - Terrain awareness and warning system.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 2 2011-01-01 2011-01-01 false Terrain awareness and warning system. 91..., and Certificate Requirements § 91.223 Terrain awareness and warning system. (a) Airplanes manufactured... seat, unless that airplane is equipped with an approved terrain awareness and warning system that as...

  12. 14 CFR 91.223 - Terrain awareness and warning system.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 2 2014-01-01 2014-01-01 false Terrain awareness and warning system. 91..., and Certificate Requirements § 91.223 Terrain awareness and warning system. (a) Airplanes manufactured... seat, unless that airplane is equipped with an approved terrain awareness and warning system that as...

  13. 14 CFR 91.223 - Terrain awareness and warning system.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Terrain awareness and warning system. 91..., and Certificate Requirements § 91.223 Terrain awareness and warning system. (a) Airplanes manufactured... seat, unless that airplane is equipped with an approved terrain awareness and warning system that as...

  14. 47 CFR 80.759 - Average terrain elevation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Average terrain elevation. 80.759 Section 80... Average terrain elevation. (a)(1) Draw radials from the antenna site for each 45 degrees of azimuth...) Calculate the height above average terrain by averaging the values calculated for each radial....

  15. Rolling ball algorithm as a multitask filter for terrain conductivity measurements

    NASA Astrophysics Data System (ADS)

    Rashed, Mohamed

    2016-09-01

    Portable frequency domain electromagnetic devices, commonly known as terrain conductivity meters, have become increasingly popular in recent years, especially in locating underground utilities. Data collected using these devices, however, usually suffer from major problems such as complexity and interference of apparent conductivity anomalies, near edge local spikes, and fading of conductivity contrast between a utility and the surrounding soil. This study presents the experience of adopting the rolling ball algorithm, originally designed to remove background from medical images, to treat these major problems in terrain conductivity measurements. Applying the proposed procedure to data collected using different terrain conductivity meters at different locations and conditions proves the capability of the rolling ball algorithm to treat these data both efficiently and quickly.

  16. Comparison of dry deposition estimates of AERMOD and CALPUFF from area sources in flat terrain

    NASA Astrophysics Data System (ADS)

    Tartakovsky, Dmitry; Stern, Eli; Broday, David M.

    2016-10-01

    The dry deposition algorithms of AERMOD and CALPUFF were compared, studying emissions from hypothetical area and point sources in flat terrain. The deposited fractions calculated by AERMOD and CALPUFF are different for the C, D and F stability classes. In all the studied scenarios the differences between the deposited fractions calculated by AERMOD and CALPUFF are much smaller than those calculated previously in complex terrain. Yet, the detected differences in the deposited fractions may affect the ambient concentrations calculated by AERMOD and CALPUFF in the receptor points as a part of an environmental impact assessment and lead to different conclusions on the residents' exposure. The distinct account of AERMOD and CALPUFF to certain wind speeds and stability classes, and their different algorithms for calculating the dispersion coefficients, is the only explanation for the different estimates of deposited fractions between AERMOD and CALPUFF over absolutely flat terrain.

  17. A model for the origin of Martian polygonal terrain

    NASA Technical Reports Server (NTRS)

    Mcgill, G. E.

    1993-01-01

    Extensive areas of the Martian northern plains in Utopia and Acidalia Planitiae are characterized by 'polygonal terrain.' Polygonal terrain consists of material cut by complex troughs defining a pattern resembling mudcracks, columnar joints, or frost-wedge polygons on the Earth. However, the Martian polygons are orders of magnitude larger than these potential Earth analogs, leading to severe mechanical difficulties for genetic models based on simple analogy arguments. Stratigraphic studies show that the polygonally fractured material in Utopia Planitia was deposited on a land surface with significant topography, including scattered knobs and mesas, fragments of ancient crater rims, and fresh younger craters. Sediments or volcanics deposited over topographically irregular surfaces can experience differential compaction producing drape folds. Bending stresses due to these drape folds would be superposed on the pervasive tensile stresses due to desiccation or cooling, such that the probability of fracturing is enhanced above buried topographic highs and suppressed above buried topographic lows. Thus it was proposed that the scale of the Martian polygons is controlled by the spacing of topographic highs on the buried surface rather than by the physics of the shrinkage process.

  18. Remote sensing of earth terrain

    NASA Technical Reports Server (NTRS)

    Yueh, Herng-Aung; Kong, Jin AU

    1991-01-01

    In remote sensing, the encountered geophysical media such as agricultural canopy, forest, snow, or ice are inhomogeneous and contain scatters in a random manner. Furthermore, weather conditions such as fog, mist, or snow cover can intervene the electromagnetic observation of the remotely sensed media. In the modelling of such media accounting for the weather effects, a multi-layer random medium model has been developed. The scattering effects of the random media are described by three-dimensional correlation functions with variances and correlation lengths corresponding to the fluctuation strengths and the physical geometry of the inhomogeneities, respectively. With proper consideration of the dyadic Green's function and its singularities, the strong fluctuation theory is used to calculate the effective permittivities which account for the modification of the wave speed and attenuation in the presence of the scatters. The distorted Born approximation is then applied to obtain the correlations of the scattered fields. From the correlation of the scattered field, calculated is the complete set of scattering coefficients for polarimetric radar observation or brightness temperature in passive radiometer applications. In the remote sensing of terrestrial ecosystems, the development of microwave remote sensing technology and the potential of SAR to measure vegetation structure and biomass have increased effort to conduct experimental and theoretical researches on the interactions between microwave and vegetation canopies. The overall objective is to develop inversion algorithms to retrieve biophysical parameters from radar data. In this perspective, theoretical models and experimental data are methodically interconnected in the following manner: Due to the complexity of the interactions involved, all theoretical models have limited domains of validity; the proposed solution is to use theoretical models, which is validated by experiments, to establish the region in which

  19. Microwave emission and scattering from vegetated terrain

    NASA Technical Reports Server (NTRS)

    Sibley, T. G.

    1973-01-01

    Models are developed for the apparent temperature and backscattering coefficient of vegetated terrain to illustrate the effects of vegetation on the sensitivity of these parameters to variations of soil moisture. Three types of terrain are simulated for both the passive and the active case: a uniform canopy over a smooth surface, plant rows on a smooth surface, and plant rows on a rough surface. In each case the canopy is defined by its overall dimensions and by its electric permittivity, which is determined from Weiner model for dielectric mixture. Emission and scattering from both the soil and the canopy are considered, but atmospheric effects are neglected. Calculated data indicate that the sensitivity of the apparent temperature and backscattering coefficient to variations of soil moisture, decreases as the amount of vegetation increases. It is shown that the same effect results from increasing signal frequency or angle of incidence.

  20. Global multi-resolution terrain elevation data 2010 (GMTED2010)

    USGS Publications Warehouse

    Danielson, Jeffrey J.; Gesch, Dean B.

    2011-01-01

    In 1996, the U.S. Geological Survey (USGS) developed a global topographic elevation model designated as GTOPO30 at a horizontal resolution of 30 arc-seconds for the entire Earth. Because no single source of topographic information covered the entire land surface, GTOPO30 was derived from eight raster and vector sources that included a substantial amount of U.S. Defense Mapping Agency data. The quality of the elevation data in GTOPO30 varies widely; there are no spatially-referenced metadata, and the major topographic features such as ridgelines and valleys are not well represented. Despite its coarse resolution and limited attributes, GTOPO30 has been widely used for a variety of hydrological, climatological, and geomorphological applications as well as military applications, where a regional, continental, or global scale topographic model is required. These applications have ranged from delineating drainage networks and watersheds to using digital elevation data for the extraction of topographic structure and three-dimensional (3D) visualization exercises (Jenson and Domingue, 1988; Verdin and Greenlee, 1996; Lehner and others, 2008). Many of the fundamental geophysical processes active at the Earth's surface are controlled or strongly influenced by topography, thus the critical need for high-quality terrain data (Gesch, 1994). U.S. Department of Defense requirements for mission planning, geographic registration of remotely sensed imagery, terrain visualization, and map production are similarly dependent on global topographic data. Since the time GTOPO30 was completed, the availability of higher-quality elevation data over large geographic areas has improved markedly. New data sources include global Digital Terrain Elevation Data (DTEDRegistered) from the Shuttle Radar Topography Mission (SRTM), Canadian elevation data, and data from the Ice, Cloud, and land Elevation Satellite (ICESat). Given the widespread use of GTOPO30 and the equivalent 30-arc

  1. Mars Global Surveyor observations of Martian fretted terrain

    USGS Publications Warehouse

    Carr, M.H.

    2001-01-01

    The Martian fretted terrain between latitudes 30?? and 50?? N and between 315?? and 360?? W has been reexamined in light of new Mars Orbiter Camera (MOC) and Mars Orbiter Laser Altimeter (MOLA) data from Mars Global Surveyor. Much of the terrain in the 30??-50?? latitude belt in both hemispheres has a characteristic stippled or pitted texture at MOC (1.5 m) scale. The texture appears to result from partial removal of a formerly smooth, thin deposit as a result of sublimation and deflation. A complex history of deposition and exhumation is indicated by remnants of a former, thicker cover of layered deposits. In some hollows and on some slopes, particularly those facing the pole, are smooth textured deposits outlined by an outward facing escarpment. Throughout the study area are numerous escarpments with debris flows at their base. The escarpments typically have slopes in the 20??-30?? range. At the base of the escarpment is commonly a deposit with striae oriented at right angles to the escarpment. Outside this deposit is the main debris apron with a surface that typically slopes 2??-3?? and complex surface textures suggestive of compression, sublimation, and deflation. The presence of undeformed impact craters indicates that the debris flows are no longer forming. Fretted valleys contain lineated fill and are poorly graded. They likely form from fluvial valleys that were initially like those elsewhere on the planet but were subsequently widened and filled by the same mass-wasting processes that formed the debris aprons. Slope reversals indicate that downvalley flow of the lineated fill is minor. The ubiquitous presence of breaks in slope formed by mass wasting and the complex surface textures that result from mass wasting, deflation, and sublimation decreases the recognizability of the shorelines formerly proposed for this area.

  2. Large Terrain Continuous Level of Detail 3D Visualization Tool

    NASA Technical Reports Server (NTRS)

    Myint, Steven; Jain, Abhinandan

    2012-01-01

    This software solved the problem of displaying terrains that are usually too large to be displayed on standard workstations in real time. The software can visualize terrain data sets composed of billions of vertices, and can display these data sets at greater than 30 frames per second. The Large Terrain Continuous Level of Detail 3D Visualization Tool allows large terrains, which can be composed of billions of vertices, to be visualized in real time. It utilizes a continuous level of detail technique called clipmapping to support this. It offloads much of the work involved in breaking up the terrain into levels of details onto the GPU (graphics processing unit) for faster processing.

  3. Terrain segmentation using laser radar range data.

    PubMed

    Letalick, D; Millnert, M; Renhorn, I

    1992-05-20

    A novel approach to segmentation of laser radar range images is presented. The approach is based on modeling horizontal and vertical scans of the terrain as piecewise-constant or piecewise-linear functions. The approach uses adaptive estimation based on Kalman filtering techniques. The performance of the segmentation algorithm is evaluated by application to laser range measurements. We also discuss how the output from the segmentation algorithm can be used for, e.g., object detection.

  4. Fractures in Transitional Terrain on Ganymede

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This area of dark terrain on Jupiter's moon Ganymede lies near a transitional area between dark and bright terrain. The dark surface is cut by a pervasive network of fractures, which range in width from the limit of resolution up to 2.2 kilometers (1.4 miles). Bright material is exposed in the walls of the chasms, and dark material fills the troughs. The impurities which darken the ice on the surface of dark terrain may be only a thin veneer over a brighter ice crust. Over time, these materials may be shed down steep slopes, where they collect in low areas. The image is 68 by 54 kilometers (42 by 33 miles), and has a resolution of 190 meters (623 feet) per picture element (pixel). North is to the top. This image was obtained on September 6, 1996 by the Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft.

    The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

  5. Mobility versus terrain: a game theoretic approach

    NASA Astrophysics Data System (ADS)

    Bednarz, David; Muench, Paul

    2016-05-01

    Mobility and terrain are two sides of the same coin. You cannot describe mobility unless you describe the terrain. For example, if my world is trench warfare, the tank may be the ideal vehicle. If my world is urban warfare, clearing buildings and such, the tank may not be an ideal vehicle, perhaps an anthropomorphic robot would be better. We seek a general framework for mobility that captures the relative value of different mobility strategies. Game theory is positively the right way to analyze the interactions of rational players who behave strategically. In this paper, we will describe the interactions between a mobility player, who is trying to make it from point A to point B with one chance to refuel, and a terrain player who is trying to minimize that probability by placing an obstacle somewhere along the path from A to B. In previous work [1], we used Monte Carlo methods to analyze this mobility game, and found optimal strategies for a discretized version of the game. Here we show the relationship of this game to a classic game of timing [2], and use solution methods from that literature to solve for optimal strategies in a continuous version of this mobility game.

  6. Fusing terrain and goals: agent control in urban environments

    NASA Astrophysics Data System (ADS)

    Kaptan, Varol; Gelenbe, Erol

    2006-04-01

    The changing face of contemporary military conflicts has forced a major shift of focus in tactical planning and evaluation from the classical Cold War battlefield to an asymmetric guerrilla-type warfare in densely populated urban areas. The new arena of conflict presents unique operational difficulties due to factors like complex mobility restrictions and the necessity to preserve civilian lives and infrastructure. In this paper we present a novel method for autonomous agent control in an urban environment. Our approach is based on fusing terrain information and agent goals for the purpose of transforming the problem of navigation in a complex environment with many obstacles into the easier problem of navigation in a virtual obstacle-free space. The main advantage of our approach is its ability to act as an adapter layer for a number of efficient agent control techniques which normally show poor performance when applied to an environment with many complex obstacles. Because of the very low computational and space complexity at runtime, our method is also particularly well suited for simulation or control of a huge number of agents (military as well as civilian) in a complex urban environment where traditional path-planning may be too expensive or where a just-in-time decision with hard real-time constraints is required.

  7. Technical development to improve satellite sounding over radiatively complex terrain

    NASA Technical Reports Server (NTRS)

    Schreiner, A. J.

    1985-01-01

    High resolution topography was acquired and applied on the McIDAS system. A technique for finding the surface skin temperature in the presence of cloud and reflected sunlight was implemented in the ALPEX retrieval software and the variability of surface emissivity at microwave wavelength was examined. Data containing raw radiances for all HIRS and MSU channels for NOAA-6 and 7 were used. METEOSAT data were used to derive cloud drift and water vapor winds over the Alpine region.

  8. Wind field near complex terrain using numerical weather prediction model

    NASA Astrophysics Data System (ADS)

    Chim, Kin-Sang

    The PennState/NCAR MM5 model was modified to simulate an idealized flow pass through a 3D obstacle in the Micro- Alpha Scale domain. The obstacle used were the idealized Gaussian obstacle and the real topography of Lantau Island of Hong Kong. The Froude number under study is ranged from 0.22 to 1.5. Regime diagrams for both the idealized Gaussian obstacle and Lantau island were constructed. This work is divided into five parts. The first part is the problem definition and the literature review of the related publications. The second part briefly discuss as the PennState/NCAR MM5 model and a case study of long- range transport is included. The third part is devoted to the modification and the verification of the PennState/NCAR MM5 model on the Micro-Alpha Scale domain. The implementation of the Orlanski (1976) open boundary condition is included with the method of single sounding initialization of the model. Moreover, an upper dissipative layer, Klemp and Lilly (1978), is implemented on the model. The simulated result is verified by the Automatic Weather Station (AWS) data and the Wind Profiler data. Four different types of Planetary Boundary Layer (PBL) parameterization schemes have been investigated in order to find out the most suitable one for Micro-Alpha Scale domain in terms of both accuracy and efficiency. Bulk Aerodynamic type of PBL parameterization scheme is found to be the most suitable PBL parameterization scheme. Investigation of the free- slip lower boundary condition is performed and the simulated result is compared with that with friction. The fourth part is the use of the modified PennState/NCAR MM5 model for an idealized flow simulation. The idealized uniform flow used is nonhydrostatic and has constant Froude number. Sensitivity test is performed by varying the Froude number and the regime diagram is constructed. Moreover, nondimensional drag is found to be useful for regime identification. The model result is also compared with the analytic results by Miles (1969) and Smith (1980, 1985), and the numerical results of Stein (1992), Miranda and James (1992) and Olaffson and Bougeault (1997). It is found that the simulated result in the present study is comparable with others. The fifth part is the construction of the regime diagram for the Lantau island of Hong Kong. All eight major wind directions are discussed.

  9. Cooperative terrain model acquisition by two point-robots in planar polygonal terrains

    SciTech Connect

    Rao, N.S.V.; Protopopescu, V.

    1994-11-29

    We address the model acquisition problem for an unknown terrain by a team of two robots. The terrain may be cluttered by a finite number of polygonal obstacles with unknown shapes and positions. The robots are point-sized and equipped with visual sensors which acquire all visible parts of the terrain by scanning from their locations. The robots communicate with each other via wireless connection. The performance is measured by the number of the sensor (scan) operations which are assumed to be the most time-consuming/expensive of all the robot operations. We employ the restricted visibility graph methods in a hierarchiacal setup. For terrains with convex obstacles, the sensing time can be halved compared to a single robot implementation. For terrains with concave corners, the performance of the algorithm depends on the number of concave regions and their depths. A hierarchical decomposition of the restricted visibility graph into 2-connected components and trees is considered. Performance for the 2-robot team is expressed in terms of sizes of 2-connected components, and the sizes and diameters of the trees. The proposed algorithm and analysis can be applied to the methods based on Voronoi diagram and trapezoidal decomposition.

  10. Spatial random downscaling of rainfall signals in Andean heterogeneous terrain

    NASA Astrophysics Data System (ADS)

    Posadas, A.; Duffaut Espinosa, L. A.; Yarlequé, C.; Carbajal, M.; Heidinger, H.; Carvalho, L.; Jones, C.; Quiroz, R.

    2015-07-01

    Remotely sensed data are often used as proxies for indirect precipitation measures over data-scarce and complex-terrain areas such as the Peruvian Andes. Although this information might be appropriate for some research requirements, the extent at which local sites could be related to such information is very limited because of the resolution of the available satellite data. Downscaling techniques are used to bridge the gap between what climate modelers (global and regional) are able to provide and what decision-makers require (local). Precipitation downscaling improves the poor local representation of satellite data and helps end-users acquire more accurate estimates of water availability. Thus, a multifractal downscaling technique complemented by a heterogeneity filter was applied to TRMM (Tropical Rainfall Measuring Mission) 3B42 gridded data (spatial resolution ~ 28 km) from the Peruvian Andean high plateau or Altiplano to generate downscaled rainfall fields that are relevant at an agricultural scale (spatial resolution ~ 1 km).

  11. Tessera terrain, Venus: Characterization and models for origin and evolution

    SciTech Connect

    Bindschadler, D.L.; Head, J.W. )

    1991-04-10

    Tessera terrain is the dominant tectonic landform in the northern high latitudes of Venus mapped by the Venera 15 and 16 orbiters and is concentrated in the region between the mountain ranges of western Ishtar Terra and Aphrodite Terra. Tesserae are characterized by regionally high topography, a high degree of small scale surface roughness, and sets of intersecting tectonic features. Available Pioneer Venus line of sight gravity data suggest that tessera terrain is compensated at shallow depths relative to many topographic highs on Venus and may be supported by crustal thickness variations. Three types of tessera terrain can be defined on the basis of structural patterns: subparallel ridged terrains (T{sub sr}), trough and ridge terrain (T{sub tr}), and disrupted terrain (T{sub ds}). Observed characteristics of tessera terrain are compared to predictions of models in order to begin to address the question of its origin and evolution. Formational models, in which high topography is created along with surface deformation, include (1) horizontal convergence, (2) mantle upwelling, (3) crustal underplating, and (4) a seafloor spreading analogy. Modification models, in which deformation occurs as a response to the presence of elevated regions, consist of (1) gravity sliding and (2) gravitational relaxation. The authors find that horizontal convergence and late stage gravitational relaxation are the most consistent with basic observations for subparallel ridged terrain and disrupted terrain. Understanding of the basic structural characteristics of trough and ridge terrain is more tentative, and models involving a spreading process or convergence and relaxation merit further study.

  12. Improved All-Terrain Suspension System

    NASA Technical Reports Server (NTRS)

    Bickler, Donald B.

    1994-01-01

    Redesigned suspension system for all-terrain vehicle exhibits enhanced ability to negotiate sand and rocks. Improved six-wheel suspension system includes only two links on each side. Bogie tends to pull rear wheels with it as it climbs. Designed for rover vehicle for exploration of Mars, also has potential application in off-road vehicles, military scout vehicles, robotic emergency vehicles, and toys. Predecessors of suspension system described in "Articulated Suspension Without Springs" (NPO-17354), "Four-Wheel Vehicle Suspension System" (NPO-17407), and "High-Clearance Six-Wheel Suspension" (NPO-17821).

  13. False Color Terrain Model of Phoenix Workspace

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This is a terrain model of Phoenix's Robotic Arm workspace. It has been color coded by depth with a lander model for context. The model has been derived using images from the depth perception feature from Phoenix's Surface Stereo Imager (SSI). Red indicates low-lying areas that appear to be troughs. Blue indicates higher areas that appear to be polygons.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  14. Geomorphology and sedimentology of hummocky terrain, south-central Alberta, Canada

    NASA Astrophysics Data System (ADS)

    Munro-Stasiuk, Mandy J.

    The landscape in south-central Alberta, Canada, is dominated by a suite of landforms that formed beneath the Laurentide Ice Sheet. This thesis explores the origins of those landforms, specifically hummocky terrain. Sediments in the hummocks, hummock form, and associations with other landforms are examined to determine hummock genesis. Sediment was examined from over one hundred exposures through the "Buffalo Lake Moraine" at Travers Reservoir, McGregor Reservoir, and the Little Bow River. This belt of hummocky terrain (like most hummocky terrain regions) is traditionally interpreted as forming at, or near, the stagnating margins of the Laurentide Ice Sheet by supraglacial letdown. However, hummocks in south-central Alberta contain a complex variety of sediments and materials atypical of supraglacial letdown: in situ bedrock, thrust bedrock, lodgement till, melt-out till, sorted sand and gravel, rippled sand, rhythmically-bedded sand, silt, and clay, and pervasively sheared beds. All sediment types and deformation structures were deposited, or formed, subglacially. Also, the deposits make up in situ stratigraphies that record the history of initial Laurentide Ice Sheet advance into the area (lodgment till and thrust bedrock), the extensive accumulation of water at the bed (glaciolacustrine beds), and ice stagnation (melt-out till). Regardless of the genesis of sediments in hummocks, sedimentary units and structures are abruptly truncated by the surface that represents the hummock and trough morphology, demonstrating that the hummocks are erosional forms and that they represent a landscape unconformity. Subglacial sediments predating the erosion and subglacial eskers overlying the erosion surface strongly suggest that hummock erosion was subglacial. Also, hummock morphology, lithostratigraphy correlated from hummock to hummock, abrupt truncation at the land surface, and widespread boulder lags support meltwater erosion for hummocky terrain in the region. Well

  15. Integrating Terrain Maps Into a Reactive Navigation Strategy

    NASA Technical Reports Server (NTRS)

    Howard, Ayanna; Werger, Barry; Seraji, Homayoun

    2006-01-01

    An improved method of processing information for autonomous navigation of a robotic vehicle across rough terrain involves the integration of terrain maps into a reactive navigation strategy. Somewhat more precisely, the method involves the incorporation, into navigation logic, of data equivalent to regional traversability maps. The terrain characteristic is mapped using a fuzzy-logic representation of the difficulty of traversing the terrain. The method is robust in that it integrates a global path-planning strategy with sensor-based regional and local navigation strategies to ensure a high probability of success in reaching a destination and avoiding obstacles along the way. The sensor-based strategies use cameras aboard the vehicle to observe the regional terrain, defined as the area of the terrain that covers the immediate vicinity near the vehicle to a specified distance a few meters away.

  16. Mathematical Modeling Of The Terrain Around A Robot

    NASA Technical Reports Server (NTRS)

    Slack, Marc G.

    1992-01-01

    In conceptual system for modeling of terrain around autonomous mobile robot, representation of terrain used for control separated from representation provided by sensors. Concept takes motion-planning system out from under constraints imposed by discrete spatial intervals of square terrain grid(s). Separation allows sensing and motion-controlling systems to operate asynchronously; facilitating integration of new map and sensor data into planning of motions.

  17. Biomechanics and energetics of running on uneven terrain.

    PubMed

    Voloshina, Alexandra S; Ferris, Daniel P

    2015-03-01

    In the natural world, legged animals regularly run across uneven terrain with remarkable ease. To gain understanding of how running on uneven terrain affects the biomechanics and energetics of locomotion, we studied human subjects (N=12) running at 2.3 m s(-1) on an uneven terrain treadmill, with up to a 2.5 cm height variation. We hypothesized that running on uneven terrain would show increased energy expenditure, step parameter variability and leg stiffness compared with running on smooth terrain. Subject energy expenditure increased by 5% (0.68 W kg(-1); P<0.05) when running on uneven terrain compared with smooth terrain. Step width and length variability also increased by 27% and 26%, respectively (P<0.05). Positive and negative ankle work decreased on uneven terrain by 22% (0.413 J kg(-1)) and 18% (0.147 J kg(-1)), respectively (P=0.0001 and P=0.0008). Mean muscle activity increased on uneven terrain for three muscles in the thigh (P<0.05). Leg stiffness also increased by 20% (P<0.05) during running on uneven terrain compared with smooth terrain. Calculations of gravitational potential energy fluctuations suggest that about half of the energetic increases can be explained by additional positive and negative mechanical work for up and down steps on the uneven surface. This is consistent between walking and running, as the absolute increases in energetic cost for walking and running on uneven terrain were similar: 0.68 and 0.48 W kg(-1), respectively. These results provide insight into how surface smoothness can affect locomotion biomechanics and energetics in the real world.

  18. Snowcover influence on backscattering from terrain

    NASA Technical Reports Server (NTRS)

    Ulaby, F. T.; Abdelrazik, M.; Stiles, W. H.

    1984-01-01

    The effects of snowcover on the microwave backscattering from terrain in the 8-35 GHz region are examined through the analysis of experimental data and by application of a semiempirical model. The model accounts for surface backscattering contributions by the snow-air and snow-soil interfaces, and for volume backscattering contributions by the snow layer. Through comparisons of backscattering data for different terrain surfaces measured both with and without snowcover, the masking effects of snow are evaluated as a function of snow water equivalent and liquid water content. The results indicate that with dry snowcover it is not possible to discriminate between different types of ground surface (concrete, asphalt, grass, and bare ground) if the snow water equivalent is greater than about 20 cm (or a depth greater than 60 cm for a snow density of 0.3 g/cu cm). For the same density, however, if the snow is wet, a depth of 10 cm is sufficient to mask the underlying surface.

  19. Terrain-based routing of distribution cables

    SciTech Connect

    West, N.A.; Dwolatzky, B.; Meyer, A.S.

    1997-01-01

    Specifying the actual layout of all overhead lines and underground cables is one of the key tasks to be carried out in the design of electrical distribution networks. Voltage drop and other network calculations can be performed only after the length of each cable segment is determined. Although automatic cable routers are currently available, they are mainly for formally planned urban areas. These routers are not always appropriate for use in designing rural distribution networks, because they fail to account for some of the special circumstances found in rural areas. A more practical approach bases automatic cable routing on the terrain of a given area rather than on the layout of roads. The automatic Distribution Network Router (DNR) finds the least-cost path (not merely the shortest one) connecting two nodes. This article briefly discusses methods currently used to determine cable routes for distribution networks, the unsuitability of these methods for routing cables in rural and informal urban areas, the proposed approach that relies on dividing the terrain into cost regions, and the benefits gained in its application. Emphasis is on the practical application of the new approach.

  20. Tool for Viewing Faults Under Terrain

    NASA Technical Reports Server (NTRS)

    Siegel, Herbert, L.; Li, P. Peggy

    2005-01-01

    Multi Surface Light Table (MSLT) is an interactive software tool that was developed in support of the QuakeSim project, which has created an earthquake- fault database and a set of earthquake- simulation software tools. MSLT visualizes the three-dimensional geometries of faults embedded below the terrain and animates time-varying simulations of stress and slip. The fault segments, represented as rectangular surfaces at dip angles, are organized into collections, that is, faults. An interface built into MSLT queries and retrieves fault definitions from the QuakeSim fault database. MSLT also reads time-varying output from one of the QuakeSim simulation tools, called "Virtual California." Stress intensity is represented by variations in color. Slips are represented by directional indicators on the fault segments. The magnitudes of the slips are represented by the duration of the directional indicators in time. The interactive controls in MSLT provide a virtual track-ball, pan and zoom, translucency adjustment, simulation playback, and simulation movie capture. In addition, geographical information on the fault segments and faults is displayed on text windows. Because of the extensive viewing controls, faults can be seen in relation to one another, and to the terrain. These relations can be realized in simulations. Correlated slips in parallel faults are visible in the playback of Virtual California simulations.

  1. Implications of terrain movements in Egypt

    NASA Astrophysics Data System (ADS)

    Nassar, Mohamed M.

    1988-10-01

    The purpose of this paper is to study the causes of localized terrain movements in Egypt. The motivation behind this research has been the vast progress in constructing huge engineering structures (dams, bridge,, tall buildings, etc.) as well as extending the urban activities in many new cities. These must be properly studied to ensure their safety versus their cost and other economic factors. In addition, the recent tendency is towards building nuclear power stations whose locations must be carefully investigated against the hazard and danger of inevitable atomic leakage, especially in the case of seismically active regions. Also the discovery of new oil wells and mines and the effects of future depletion require considerable attention from qualified investigators. The relative tectonic movements of North Africa and Southern Europe, the seismic activities around the Alexandria region, the presence of faults related to the region of the High Dam and its reservoir in Aswan, the erosion of the banks of the River Nile and its islands as well as coastal lines along the Mediterranean and the Red Sea, and the deformation and damage to large buildings in the Cairo area are examined here as a few examples of the implications of the earth's deformations within Egyptian territory. Strong recommendations are made concerning the necessity of studying and monitoring the terrain movements in the areas where new cities, large engineering constructions and power plants are planned to be erected.

  2. On-the-sphere block-based 3D terrain rendering using a wavelet-encoded terrain database for SVS

    NASA Astrophysics Data System (ADS)

    Baxes, Gregory A.; Linger, Tim

    2006-05-01

    Successful integration and the ultimate adoption of 3D Synthetic Vision (SV) systems into the flight environment as a cockpit aid to pilot situational awareness (SA) depends highly on overcoming two primary engineering obstacles: 1) storing on-board terrain databases with sufficient accuracy, resolution and coverage areas; and 2) achieving real-time, deterministic, accurate and artifact-free 3D terrain rendering. These combined elements create a significant, inversely-compatible challenge to deployable SV systems that has not been adequately addressed in the realm of proliferous VisSim terrain-rendering approaches. Safety-critical SV systems for flight-deployed use, ground-control of flight systems such as UAVs and accurate mission rehearsal systems require a solution to these challenges. This paper describes the TerraMetrics TerraBlocks method of storing wavelet-encoded terrain datasets and a tightly-coupled 3D terrain-block rendering approach. Large-area terrain datasets are encoded using a wavelet transform, producing a hierarchical quadtree, powers-of-2 structure of the original terrain data at numerous levels of detail (LODs). The entire original raster terrain mesh (e.g., DTED) is transformed using either lossless or lossy wavelet transformation and is maintained in an equirectangular projection. The lossless form retains all original terrain mesh data integrity in the flight dataset. A side-effect benefit of terrain data compression is also achieved. The TerraBlocks run-time 3D terrain-block renderer accesses arbitrary, uniform-sized blocks of terrain data at varying LODs, depending on scene composition, from the wavelet-transformed terrain dataset. Terrain data blocks retain a spatially-filtered depiction of the original mesh data at the retrieved LOD. Terrain data blocks are processed as discrete objects and placed into spherical world space, relative to the viewpoint. Rendering determinacy is achieved through terrain-block LOD management and spherical

  3. Terrain Traversing Device Having a Wheel with Microhooks

    NASA Technical Reports Server (NTRS)

    Parness, Aaron (Inventor); Carpenter, Kalind C. (Inventor); Wiltsie, Nicholas (Inventor)

    2015-01-01

    A terrain traversing device is described. The device includes an annular rotor element with a plurality of co-planar microspine hooks arranged on the periphery of the annular rotor element. Each microspine hook has an independently flexible suspension configuration that permits the microspine hook to initially engage an irregularity in a terrain surface at a preset initial engagement angle and subsequently engage the irregularity with a continuously varying engagement angle when the annular rotor element is rotated for urging the terrain traversing device to traverse a terrain surface. Improvements related to the design, fabrication and use of the microspine hooks in the device are also described.

  4. Grooved Terrain on Ganymede: A Galileo-based Synthesis

    NASA Technical Reports Server (NTRS)

    Pappalardo, Robert T.; Collins, Geoffrey C.; Head, James W.; Moore, Jeffrey M.; Schenk, Paul M.

    2003-01-01

    Swaths of bright "grooved terrain" (sulci) on Ganymede are 10s to 100s of kilometers wide and cross-cut the older dark terrain, forming an intricate patchwork across 2/3 of Ganymede's surface. The view of grooved terrain developed from Voyager images is that bright cells are broad graben infilled by extrusion of relatively clean (silicate-poor) liquid water, warm ice, or icy slush, and then extended and faulted. Galileo imaging has greatly improved understanding of the emplacement history and geological implications of grooved terrain, supporting a rift-like model for its formation.

  5. Terrain Traversing Device Having a Wheel with Microhooks

    NASA Technical Reports Server (NTRS)

    Parness, Aaron (Inventor); McKenzie, Clifford F. (Inventor)

    2014-01-01

    A terrain traversing device includes an annular rotor element with a plurality of co-planar microspine hooks arranged on the periphery of the annular rotor element. Each microspine hook has an independently flexible suspension configuration that permits the microspine hook to initially engage an irregularity in a terrain surface at a preset initial engagement angle and subsequently engage the irregularity with a continuously varying engagement angle when the annular rotor element is rotated for urging the terrain traversing device to traverse a terrain surface.

  6. Turbulence sources in mountain terrain: results from MATERHORN program

    NASA Astrophysics Data System (ADS)

    Di Sabatino, Silvana; Leo, Laura S.; Fernando, Harindra J. S.; Pardyjak, Eric R.; Hocut, Chris M.

    2016-04-01

    Improving high-resolution numerical weather prediction in complex terrain is essential for the many applications involving mountain weather. It is commonly recognized that high intensity weather phenomena near mountains are a safety hazard to aircrafts and unmanned aerial vehicles, but the prediction of highly variable weather is often unsatisfactory due to inadequacy of resolution or lack of the correct dynamics in the model. Improving mountain weather forecasts has been the goal of the interdisciplinary Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) program (2011-2016). In this paper, we will report some of the findings focusing on several mechanisms of generating turbulence in near surface flows in the vicinity of an isolated mountain. Specifically, we will discuss nocturnal flows under low synoptic forcing. It has been demonstrated that such calm conditions are hard to predict in typical weather predictions models where forcing is dominated by local features that are poorly included in numerical models. It is found that downslope flows in calm and clear nights develop rapidly after sunset and usually persists for few hours. Owing to multiscale flow interactions, slope flows appear to be intermittent and disturbed, with a tendency to decay through the night yet periodically and unexpectedly generated. One of the interesting feature herein is the presence of oscillations that can be associated to different types of waves (e.g. internal and trapping waves) which may break to produce extra mixing. Pulsations of katabatic flow at critical internal-wave frequency, flow intrusions arriving from different topographies and shear layers of flow fanning out from the gaps all contribute to the weakly or intermittently turbulent state. Understanding of low frequency contributions to the total kinetic energy represent a step forward into modelling sub-grid effects in numerical models used for aviation applications.

  7. Terrain modelling and motion planning for an autonomous exploration rover

    NASA Technical Reports Server (NTRS)

    Richard, F.; Benoliel, S.; Faugeras, O.; Grandjean, P.; Hayard, M.; Simeon, T.

    1994-01-01

    To assess the feasibility of planetary exploration missions using rovers, the French national agency CNES, with a consortium of European laboratories and industrial concerns, has initiated the Eureka project, 'Illustration of an Autonomous Robot for the Exploration of Space' (IARES). IARES is a demonstrator composed of a rover and a ground station, linked by telemetry and telecommand. It is aimed at verifying, on earth, robotic concepts developed by the RISP group of French laboratories (LAAS, INRIA, CERT, LETI) to perform scientific missions such as autonomous terrain sample collecting over large areas. To cope with the actual needs of planet exploration, IARES suitability is assessed through constraints on limited bandwidth, time delay and on-board resources. This autonomy relies heavily on robust onboard trajectory generation capabilities. This paper presents the main functions of the IARES navigation sub-system and shows how they are combined to allow movement in Mars-like environments. Section 2 gives an overall description of the IARES system. Section 3 details the functions of the Navigation sub-system, and finally, section 4 illustrates with a simple example the use of these functions.

  8. Photo-realistic Terrain Modeling and Visualization for Mars Exploration Rover Science Operations

    NASA Technical Reports Server (NTRS)

    Edwards, Laurence; Sims, Michael; Kunz, Clayton; Lees, David; Bowman, Judd

    2005-01-01

    Modern NASA planetary exploration missions employ complex systems of hardware and software managed by large teams of. engineers and scientists in order to study remote environments. The most complex and successful of these recent projects is the Mars Exploration Rover mission. The Computational Sciences Division at NASA Ames Research Center delivered a 30 visualization program, Viz, to the MER mission that provides an immersive, interactive environment for science analysis of the remote planetary surface. In addition, Ames provided the Athena Science Team with high-quality terrain reconstructions generated with the Ames Stereo-pipeline. The on-site support team for these software systems responded to unanticipated opportunities to generate 30 terrain models during the primary MER mission. This paper describes Viz, the Stereo-pipeline, and the experiences of the on-site team supporting the scientists at JPL during the primary MER mission.

  9. Single-Frame Terrain Mapping Software for Robotic Vehicles

    NASA Technical Reports Server (NTRS)

    Rankin, Arturo L.

    2011-01-01

    This software is a component in an unmanned ground vehicle (UGV) perception system that builds compact, single-frame terrain maps for distribution to other systems, such as a world model or an operator control unit, over a local area network (LAN). Each cell in the map encodes an elevation value, terrain classification, object classification, terrain traversability, terrain roughness, and a confidence value into four bytes of memory. The input to this software component is a range image (from a lidar or stereo vision system), and optionally a terrain classification image and an object classification image, both registered to the range image. The single-frame terrain map generates estimates of the support surface elevation, ground cover elevation, and minimum canopy elevation; generates terrain traversability cost; detects low overhangs and high-density obstacles; and can perform geometry-based terrain classification (ground, ground cover, unknown). A new origin is automatically selected for each single-frame terrain map in global coordinates such that it coincides with the corner of a world map cell. That way, single-frame terrain maps correctly line up with the world map, facilitating the merging of map data into the world map. Instead of using 32 bits to store the floating-point elevation for a map cell, the vehicle elevation is assigned to the map origin elevation and reports the change in elevation (from the origin elevation) in terms of the number of discrete steps. The single-frame terrain map elevation resolution is 2 cm. At that resolution, terrain elevation from 20.5 to 20.5 m (with respect to the vehicle's elevation) is encoded into 11 bits. For each four-byte map cell, bits are assigned to encode elevation, terrain roughness, terrain classification, object classification, terrain traversability cost, and a confidence value. The vehicle s current position and orientation, the map origin, and the map cell resolution are all included in a header for each

  10. The GeoSAR program: Development of a commercially viable 3-D radar terrain mapping system

    SciTech Connect

    Carlisle, R.G.; Davis, M.

    1996-11-01

    GeoSAR is joint development between the Defense Advanced Research Project Agency (DARPA) and the California Department of Conservation (CA DOC) to determine the technical and economic viability of an airborne interferometric and foliage penetration synthetic aperture radar for mapping terrain and man made objects in geographical areas obscured by foliage, urban buildings, and other concealments. The two core technology elements of this program are Interferometric Synthetic Aperture Radar (IFSAR) and Foliage Penetration Radar (FOPEN). These technologies have been developed by NASA and ARPA, principally for defense applications.

  11. IFSAR for the Rapid Terrain Visualization Demonstration

    SciTech Connect

    BURNS,BRYAN L.; EICHEL,PAUL H.; HENSLEY JR.,WILLIAM H.; KIM,THEODORE J.

    2000-10-31

    The Rapid Terrain Visualization Advanced Concept Technology Demonstration (RTV-ACTD) is designed to demonstrate the technologies and infrastructure to meet the Army requirement for rapid generation of digital topographic data to support emerging crisis or contingencies. The primary sensor for this mission is an interferometric synthetic aperture radar (IFSAR) designed at Sandia National Laboratories. This paper will outline the design of the system and its performance, and show some recent flight test results. The RTV IFSAR will meet DTED level III and IV specifications by using a multiple-baseline design and high-accuracy differential and carrier-phase GPS navigation. It includes innovative near-real-time DEM production on-board the aircraft. The system is being flown on a deHavilland DHC-7 Army aircraft.

  12. Potassium fertility and terrain attributes in a Fragiudalf drainage Catena

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Site-specific management of soil fertility has been based on soil sampling in grid patterns or within soil mapping units without taking full advantage of terrain/soil relationships, often thought to pertain to pedology as a separate discipline. The topographic wetness index (TWI), a terrain attribut...

  13. Intra-Annual Variations of the Martian Swiss Cheese Terrain

    NASA Astrophysics Data System (ADS)

    Titus, T. N.; Cushing, G.; Pathare, A.; Christensen, P. R.; Byrne, S.; Ivanov, A. B.; Ingersoll, A.; Richardson, M.; Kirk, R. L.; Soderblom, L. A.; Themis Team

    2004-03-01

    Much of the surface of the carbon dioxide South Polar Residual Cap of Mars consists of quasi-circular pits with steep walls that have been dubbed "Swiss Cheese" terrain. Here, we examine the intra-annual variations of the Martian Swiss Cheese terrain using both MOC and THEMIS VIS/IR imaging.

  14. Adaptive surface meshing and multiresolution terrain depiction for SVS

    NASA Astrophysics Data System (ADS)

    Wiesemann, Thorsten; Schiefele, Jens; Kubbat, Wolfgang

    2001-08-01

    Many of today's and tomorrow's aviation applications demand accurate and reliable digital terrain elevation databases. Particularly future Vertical Cut Displays or 3D Synthetic Vision Systems (SVS) require accurate and hi-resolution data to offer a reliable terrain depiction. On the other hand, optimized or reduced terrain models are necessary to ensure real-time rendering and computing performance. In this paper a new method for adaptive terrain meshing and depiction for SVS is presented. The initial data set is decomposed by using a wavelet transform. By examining the wavelet coefficients, an adaptive surface approximation for various Level-of-Detail is determined. Additionally, the dyadic scaling of the wavelet transform is used to build a hierarchical quad-tree representation for the terrain data. This representation enhances fast interactive computations and real-time rendering methods. The proposed terrain representation is integrated into a standard navigation display. Due to the multi-resolution data organization, terrain depiction e.g. resolution is adaptive to a selected zooming level or flight phase. Moreover, the wavelet decomposition helps to define local regions of interest. A depicted terrain resolution has a finer grain nearby the current airplane position and gets coarser with increasing aircraft distance. In addition, flight critical regions can be depicted in a higher resolution.

  15. 14 CFR 135.154 - Terrain awareness and warning system.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Terrain awareness and warning system. 135... Aircraft and Equipment § 135.154 Terrain awareness and warning system. (a) Airplanes manufactured after... passenger seats, excluding any pilot seat, unless that airplane is equipped with an approved...

  16. 14 CFR 121.354 - Terrain awareness and warning system.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Terrain awareness and warning system. 121... § 121.354 Terrain awareness and warning system. (a) Airplanes manufactured after March 29, 2002. No person may operate a turbine-powered airplane unless that airplane is equipped with an approved...

  17. 14 CFR 121.354 - Terrain awareness and warning system.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Terrain awareness and warning system. 121... § 121.354 Terrain awareness and warning system. (a) Airplanes manufactured after March 29, 2002. No person may operate a turbine-powered airplane unless that airplane is equipped with an approved...

  18. 14 CFR 121.354 - Terrain awareness and warning system.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Terrain awareness and warning system. 121... § 121.354 Terrain awareness and warning system. (a) Airplanes manufactured after March 29, 2002. No person may operate a turbine-powered airplane unless that airplane is equipped with an approved...

  19. 14 CFR 135.154 - Terrain awareness and warning system.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Terrain awareness and warning system. 135... Aircraft and Equipment § 135.154 Terrain awareness and warning system. (a) Airplanes manufactured after... passenger seats, excluding any pilot seat, unless that airplane is equipped with an approved...

  20. 14 CFR 135.154 - Terrain awareness and warning system.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Terrain awareness and warning system. 135... Aircraft and Equipment § 135.154 Terrain awareness and warning system. (a) Airplanes manufactured after... passenger seats, excluding any pilot seat, unless that airplane is equipped with an approved...

  1. What Influences Youth to Operate All-Terrain Vehicles Safely?

    ERIC Educational Resources Information Center

    Grummon, A. H.; Heaney, C. A.; Dellinger, W. A.; Wilkins, J. R., III

    2014-01-01

    The operation of all-terrain vehicles (ATVs) by youth has contributed to the incidence of serious and fatal injuries among children. This study explored factors related to the frequency with which youth wore a helmet and refrained from engaging in three risky driving behaviors (driving at risky speeds, on paved roads and on unfamiliar terrain)…

  2. 14 CFR 121.354 - Terrain awareness and warning system.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Terrain awareness and warning system. 121... § 121.354 Terrain awareness and warning system. (a) Airplanes manufactured after March 29, 2002. No person may operate a turbine-powered airplane unless that airplane is equipped with an approved...

  3. 14 CFR 135.154 - Terrain awareness and warning system.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Terrain awareness and warning system. 135... Aircraft and Equipment § 135.154 Terrain awareness and warning system. (a) Airplanes manufactured after... passenger seats, excluding any pilot seat, unless that airplane is equipped with an approved...

  4. 14 CFR 135.154 - Terrain awareness and warning system.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Terrain awareness and warning system. 135... Aircraft and Equipment § 135.154 Terrain awareness and warning system. (a) Airplanes manufactured after... passenger seats, excluding any pilot seat, unless that airplane is equipped with an approved...

  5. 14 CFR 121.354 - Terrain awareness and warning system.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Terrain awareness and warning system. 121... § 121.354 Terrain awareness and warning system. (a) Airplanes manufactured after March 29, 2002. No person may operate a turbine-powered airplane unless that airplane is equipped with an approved...

  6. Tessera terrain, Venus - Characterization and models for origin and evolution

    NASA Astrophysics Data System (ADS)

    Bindschadler, D. L.; Head, J. W.

    1991-04-01

    Tessera terrain is the dominant tectonic landform in the northern high latitudes of Venus mapped by the Venera 15 and 16 orbiters and is concentrated in the region between the mountain ranges of western Ishtar Terra and Aphrodite Terra. Tesserae are characterized by regionally high topography, a high-degree of small scale surface roughness, and sets of intersecting tectonic features. Available Pioneer Venus line of sight gravity data suggest that tessera terain is compensated at shallow depths relative to many topographic highs on Venus and may be supported by crustal thickness variations. Three types of tessera terrain can be defined on the basis of structural patterns: subparallel ridged terrain (Tsr), trough and ridge terrain (Ttr), and disrupted terrain (Tds). Observed characteristics of tessera terrain are compared to predictions of formational and modificational models in order to begin to address the question of its origin and evolution. It is found that horizontal convergence and late stage gravitational relaxation are basic observations for subparallel ridged terrain and disrupted terrain.

  7. The transition from an Archean granite-greenstone terrain into a charnockite terrain in southern India

    NASA Technical Reports Server (NTRS)

    Condie, K. C.; Allen, P.

    1983-01-01

    In southern India, it is possible to study the transition from an Archean granite-greenstone terrain (the Karnataka province) into high grade charnockites. The transition occurs over an outcrop width of 20-35 km and appears to represent burial depths ranging from 15 to 20 km. Field and geochemical studies indicate that the charnockites developed at the expense of tonalites, granites, and greenstones. South of the transition zone, geobarometer studies indicate burial depths of 7-9 kb.

  8. Development of a terrain severity measurement system utilizing optical lasers

    NASA Astrophysics Data System (ADS)

    Dembski, Nicholas; Rizzoni, Giorgio; Soliman, Ahmed

    2006-05-01

    A terrain severity measurement system utilizing non-contact optical scanning laser technologies employed in on-road profiling has been developed to make detailed measurements of the relative smoothness of all types of terrain from paved roads to extreme off-road conditions. The objectives included operation in all climatic conditions, simplified operation, and rapid availability of data. Accelerometers and inclinometers are used to measure laser sensor movement in order to eliminate measurement errors due to vehicle pitch and roll. A GPS receiver is used to correlate terrain profile information to position and elevation data. The end result is an accurate description of the longitudinal and lateral terrain profile that can be used to characterize the terrain and within vehicle modeling and simulation programs.

  9. Terrain topography measurement using multipass polarimetric synthetic aperture radar data

    NASA Astrophysics Data System (ADS)

    Schuler, Dale L.; Lee, Jong-Sen; Ainsworth, Thomas L.; Grunes, Mitchell R.

    2000-05-01

    A method has been investigated for the measurement of topography using airborne fully polarimetric synthetic aperture radar (SAR) data. Terrain slopes in both the range and azimuthal directions have been estimated using multipass flight geometries. Using these slope values, the Poisson equation was then solved to create a Digital Elevation Model (DEM) of the terrain topography. The method measures polarimetric orientation angles which are then converted into terrain slopes in the azimuthal direction. The conversion of these orientation angles into terrain slopes requires additional knowledge of the radar look angle and the range direction terrain slopes. The solution for slopes is, therefore, a problem coupled between the range and azimuthal directions. For specialized multipass flight geometries these orthogonal terrain slopes are solved for, and maps of terrain slopes are produced. In particular, the processing of two-pass orthogonal and two-pass antiparallel (headings Θ and Θ+ 180°) NASA - Jet Propulsion Laboratory airborne SAR data sets has been carried out for an area in central California. When orthogonal slopes are derived using either of these data sets, a digital elevation model may be generated. The L band, polarimetric SAR (POLSAR) DEM created by this solution is compared to a coregistered C band, interferometric SAR (IFSAR) DEM. Similar comparisons are made for terrain slopes in the azimuthal - range directions which are generated by the POLSAR and IFSAR elevation data. The polarimetric SAR, operating from an aircraft, or satellite, in a strip-mapping mode, is capable of measuring terrain topography for large areas provided that phase-preserving fully polarimetric data are taken. Polarimetric SAR data are also widely used for studies of crop classification, surface roughness, biomass density, and soil moisture content. All of these studies are adversely affected by scattering changes attributable to topography. The technique investigated here

  10. Soft computing-based terrain visual sensing and data fusion for unmanned ground robotic systems

    NASA Astrophysics Data System (ADS)

    Shirkhodaie, Amir

    2006-05-01

    In this paper, we have primarily discussed technical challenges and navigational skill requirements of mobile robots for traversability path planning in natural terrain environments similar to Mars surface terrains. We have described different methods for detection of salient terrain features based on imaging texture analysis techniques. We have also presented three competing techniques for terrain traversability assessment of mobile robots navigating in unstructured natural terrain environments. These three techniques include: a rule-based terrain classifier, a neural network-based terrain classifier, and a fuzzy-logic terrain classifier. Each proposed terrain classifier divides a region of natural terrain into finite sub-terrain regions and classifies terrain condition exclusively within each sub-terrain region based on terrain visual clues. The Kalman Filtering technique is applied for aggregative fusion of sub-terrain assessment results. The last two terrain classifiers are shown to have remarkable capability for terrain traversability assessment of natural terrains. We have conducted a comparative performance evaluation of all three terrain classifiers and presented the results in this paper.

  11. Government-Based Training Agencies and the Professional Development of Indonesian Teachers of English for Young Learners: Perspectives from Complexity Theory

    ERIC Educational Resources Information Center

    Zein, Mochamad Subhan

    2016-01-01

    This study was conducted to identify suggestions to improve PD programmes held by government-based training agencies to help enhance Indonesian EYL teachers' instructional practice. For the purpose of the study, semi-structured interviews were conducted with 51 participants. The findings suggest the theorisation of a PD model that involves complex…

  12. "I Could Have Done Everything and Why Not?": Young Women's Complex Constructions of Sexual Agency in the Context of Sexualities Education in Life Orientation in South African Schools

    ERIC Educational Resources Information Center

    Kruger, Lou-Marie; Shefer, Tamara; Oakes, Antoinette

    2015-01-01

    Progressive policies protecting women's rights to make reproductive decisions and the recent increase in literature exploring female sexual agency do not appear to have impacted on more equitable sexual relations in all contexts. In South Africa, gender power inequalities, intersecting with other forms of inequality in society, pose a challenge…

  13. Meso-beta scale numerical simulation studies of terrain-induced jet streak mass/momentum perturbations

    NASA Technical Reports Server (NTRS)

    Lin, Yuh-Lang; Kaplan, Michael L.

    1992-01-01

    Work performed during the report period is summarized. The first numerical experiment which was performed on the North Carolina Supercomputer Center's CRAY-YMP machine during the second half of FY92 involved a 36 hour simulation of the CCOPE case study. This first coarse-mesh simulation employed the GMASS model with a 178 x 108 x 32 matrix of grid points spaced approximately 24 km apart. The initial data was comprised of the global 2.5 x 2.5 degree analyses as well as all available North American rawinsonde data valid at 0000 UTC 11 July 1981. Highly-smoothed LFM-derived terrain data were utilized so as to determine the mesoscale response of the three-dimensional atmosphere to weak terrain forcing prior to including the observed highly complex terrain of the northern Rocky Mountain region. It was felt that the model should be run with a spectrum of terrain geometries, ranging from observed complex terrain to no terrain at all, to determine how crucial the terrain was in forcing the mesoscale phenomena. Both convection and stratiform (stable) precipitation were not allowed in this simulation so that their relative importance could be determined by inclusion in forth-coming simulations. A full suite of planetary boundary layer forcing was allowed in the simulation, including surface sensible and latent heat fluxes employing the Blakadar PBL formulation. The details of this simulation, which in many ways could be considered the control simulation, including the important synoptic-scale, meso-alpha scale, and meso-beta scale circulations is described. These results are compared to the observations diagnosed by Koch and his colleagues as well as hypotheses set forth in the project proposal for terrain-influences upon the jet stream and their role in the generation of mesoscale wave phenomenon. The fundamental goal of the analyses being the discrimination among background geostrophic adjustment, terrain influences, and shearing instability in the initiation and

  14. Investigation of the three-dimensional actinic flux field in mountainous terrain

    NASA Astrophysics Data System (ADS)

    Wagner, J. E.; Angelini, F.; Blumthaler, M.; Fitzka, M.; Gobbi, J. P.; Kift, R.; Kreuter, A.; Rieder, H. E.; Webb, A.; Weihs, P.

    2010-09-01

    Spectrally resolved high quality actinic flux measurements between 290 nm and 500 nm have been performed in complex Alpine terrain under clear sky conditions. A three-dimensional Monte Carlo radiative transfer model was adapted for actinic flux calculations in mountainous terrain. This model is used to study the impact of topography and surface albedo on surface spectral actinic flux and no2- and o3-photolysis rates. This approach leads to surface maps of actinic flux and photolysis rates. The typical high spatial variability due to altitude, snow cover and shading affects is very well reproduced in the model. By running the model in three modes (realistic, without topography, with albedo zero) one gets a good estimation of the impact of topography and surface albedo.

  15. Automated wide-angle SAR stereo height extraction in rugged terrain using shift-scaling correlation.

    SciTech Connect

    Yocky, David Alan; Jakowatz, Charles V., Jr.

    2003-07-01

    Coherent stereo pairs from cross-track synthetic aperture radar (SAR) collects allow fully automated correlation matching using magnitude and phase data. Yet, automated feature matching (correspondence) becomes more difficult when imaging rugged terrain utilizing large stereo crossing angle geometries because high-relief features can undergo significant spatial distortions. These distortions sometimes cause traditional, shift-only correlation matching to fail. This paper presents a possible solution addressing this difficulty. Changing the complex correlation maximization search from shift-only to shift-and-scaling using the downhill simplex method results in higher correlation. This is shown on eight coherent spotlight-mode cross-track stereo pairs with stereo crossing angles averaging 93.7{sup o} collected over terrain with slopes greater than 20{sup o}. The resulting digital elevation maps (DEMs) are compared to ground truth. Using the shift-scaling correlation approach to calculate disparity, height errors decrease and the number of reliable DEM posts increase.

  16. Venusian impact basins and cratered terrains

    NASA Technical Reports Server (NTRS)

    Hamilton, Warren B.

    1992-01-01

    The consensus regarding interpretation of Magellan radar imagery assigns Venus a young volcanic surface subjected in many areas to moderate crustal shortening. I infer that, on the contrary, ancient densely cratered terrain and large impact basins may be preserved over more than half the planet and that crustal shortening has been much overestimated. I see wind erosion and deposition as far more effective in modifying old structures. Integration with lunar chronology suggests that most of the surface of Venus may be older than 3.0 Ga and much may be older than 3.8 Ga. Broad volcanos, hug volcanic domes, plains preserving lobate flow patterns, and numerous lesser volcanic features, pocked sparsely by impact craters, are indeed obvious on Magellan imagery. Some of these postvolcanic impact craters have been slightly extended, but only a small portion has been flooded by still younger lavas. Relative ages of the young craters are indicated by the varying eolian removal of their forms and ejecta blankets and flow lobes, and the oldest are much subdued. If these young impact craters, maximum diameter 275 km, include all preserved impact structures, then their quantity and distribution indicate that Venus was largely resurfaced by volcanism approx. 0.5 Ga, subsequent eruptions having been at a much reduced rate. Away from the approx. 0.5 Ga volcanic features, much of Venus is, however, dominated by circular and subcircular features, 50-2000 km in diameter, many of them multiring, that may be mostly older impact and impact-melt structures substantially modified by wind action. Eolian erosion scoured to bedrock old ridges and uplands, including those that may be cratered terrains and the rims and outer-ring depressions of large impact basins, and removed all surficial deposits to the limits of resolution of the imagery. The complementary eolian deposits form not only dunes, wind streaks, and small plains, but also broad radar-dark plains, commonly assumed to be volcanic

  17. Comparison between Dione’ and Enceladus’ terrain units

    NASA Astrophysics Data System (ADS)

    Scipioni, Francesca; Tosi, F.; Stephan, K.; Filacchione, G.; Capaccioni, F.; Cerroni, P.

    2013-10-01

    Dione has a diameter of 1122 km and a density of ρ = 1.475 g/cm3. Most of Dione’ surface is covered by the heavily cratered terrains, located mainly in the trailing hemisphere and crossed by high-albedo wispy streaks that are likely tectonic features. Enceladus has a mean diameter of 504 km and its surface appears to be completely made up of pure water ice. Form data acquired by Cassini spacecraft it was observed a present-day geologic activity coming from the South polar region. Plumes of micron-sized particles of water ice erupting from this region represent the major source of the E-ring. The VIMS spectrometer is able to acquire hyperspectral cubes in the overall spectral range from 0.3 to 5.1 µm. We select VIMS cubes of Dione and Enceladus in the IR range between 0.8 and 5.1 µm and we normalize all spectra at λ=2.232 µm in different illumination conditions effects. We apply a clustering technique to the spectra of each cube based on the supervised method Spectral Angle Mapper (SAM) to emphasize the presence of spectral units. The endmembers used by the SAM for the classification of each terrain type, were selected applying the unsupervised clustering technique k-means to the cubes with the highest spatial resolution. In particular, k-means technique identified nine endmembers for Dione. To summarize the result of the SAM classification, we projected classified cube’s pixels on a Dione’s cylindrical map. For both satellites, the infrared spectrum is dominated by the prominent signatures of H2O ice /OH bands at 1.5, 2.0 and 3.0 µm. We conclude that a classification method applied to VIMS hyperspectral data is crucial to understand geochemical processes taking place on the surface of the icy satellites. From our analysis we find that several spectral units on the two satellites are characterized by different values of the spectral indices, such as the water ice bands’ depths, which are indicators of the water ice grain size and abundance. Particles

  18. Comparison between Dione' and Enceladus' terrain units

    NASA Astrophysics Data System (ADS)

    Scipioni, F.; Tosi, F.; Stephan, K.; Filacchione, G.; Ciarniello, M.; Cerroni, P.

    2013-12-01

    Dione has a diameter of 1122 km and a density of ρ = 1.475 g/cm3. Most of Dione' surface is covered by the heavily cratered terrains, located mainly in the trailing hemisphere and crossed by high-albedo wispy streaks that are likely tectonic features. Enceladus has a mean diameter of 504 km and its surface appears to be completely made up of pure water ice. Form data acquired by Cassini spacecraft it was observed a present-day geologic activity coming from the South polar region. Plumes of micron-sized particles of water ice erupting from this region represent the major source of the E-ring. The VIMS spectrometer is able to acquire hyperspectral cubes in the overall spectral range from 0.3 to 5.1 μm. We select VIMS cubes of Dione and Enceladus in the IR range between 0.8 and 5.1 μm and we normalize all spectra at λ=2.232 µm in different illumination conditions effects. We apply a clustering technique to the spectra of each cube based on the supervised method Spectral Angle Mapper (SAM) to emphasize the presence of spectral units. The endmembers used by the SAM for the classification of each terrain type, were selected applying the unsupervised clustering technique k-means to the cubes with the highest spatial resolution. In particular, k-means technique identified nine endmembers for Dione. To summarize the result of the SAM classification, we projected classified cube's pixels on a Dione's cylindrical map. For both satellites, the infrared spectrum is dominated by the prominent signatures of H2O ice /OH bands at 1.5, 2.0 and 3.0 μm. We conclude that a classification method applied to VIMS hyperspectral data is crucial to understand geochemical processes taking place on the surface of the icy satellites. From our analysis we find that several spectral units on the two satellites are characterized by different values of the spectral indices, such as the water ice bands' depths, which are indicators of the water ice grain size and abundance. Particles of

  19. New Vocabulary: Araneiform and Lace Terrains

    NASA Technical Reports Server (NTRS)

    2007-01-01

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] Figure 1Figure 2

    The south polar terrain on Mars contains landforms unlike any that we see on Earth, so much that a new vocabulary is required to describe them. The word 'araneiform' means 'spider-like.' There are radially organized channels on Mars that look spider-like, but we don't want to confuse anyone by talking about 'spiders' when we really mean 'channels,' not 'bugs.'

    The first subimage (figure 1) shows an example of 'connected araneiform topography,' terrain that is filled with spider-like channels whose arms branch and connect to each other. Gas flows through these channels until it encounters a vent, where is escapes out to the atmosphere, carrying dust along with it. The dark dust is blown around by the prevailing wind.

    The second subimage (figure 2) shows a different region of the same image where the channels are not radially organized. In this region they form a dense tangled network of tortuous strands. We refer to this as 'lace.'

    Observation Geometry Image PSP_002651_0930 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 18-Feb-2007. The complete image is centered at -86.9 degrees latitude, 97.2 degrees East longitude. The range to the target site was 268.7 km (167.9 miles). At this distance the image scale is 53.8 cm/pixel (with 2 x 2 binning) so objects 161 cm across are resolved. The image shown here has been map-projected to 50 cm/pixel . The image was taken at a local Mars time of 04:56 PM and the scene is illuminated from the west with a solar incidence angle of 86 degrees, thus the sun was about 4 degrees above the horizon. At a solar longitude of 186.4 degrees, the season on Mars is Northern Autumn.

  20. MRO CTX-based Digital Terrain Models

    NASA Astrophysics Data System (ADS)

    Dumke, Alexander

    2016-04-01

    In planetary surface sciences, digital terrain models (DTM) are paramount when it comes to understanding and quantifying processes. In this contribution an approach for the derivation of digital terrain models from stereo images of the NASA Mars Reconnaissance Orbiter (MRO) Context Camera (CTX) are described. CTX consists of a 350 mm focal length telescope and 5000 CCD sensor elements and is operated as pushbroom camera. It acquires images with ~6 m/px over a swath width of ~30 km of the Mars surface [1]. Today, several approaches for the derivation of CTX DTMs exist [e. g. 2, 3, 4]. The discussed approach here is based on established software and combines them with proprietary software as described below. The main processing task for the derivation of CTX stereo DTMs is based on six steps: (1) First, CTX images are radiometrically corrected using the ISIS software package [5]. (2) For selected CTX stereo images, exterior orientation data from reconstructed NAIF SPICE data are extracted [6]. (3) In the next step High Resolution Stereo Camera (HRSC) DTMs [7, 8, 9] are used for the rectification of CTX stereo images to reduce the search area during the image matching. Here, HRSC DTMs are used due to their higher spatial resolution when compared to MOLA DTMs. (4) The determination of coordinates of homologous points between stereo images, i.e. the stereo image matching process, consists of two steps: first, a cross-correlation to obtain approximate values and secondly, their use in a least-square matching (LSM) process in order to obtain subpixel positions. (5) The stereo matching results are then used to generate object points from forward ray intersections. (6) As a last step, the DTM-raster generation is performed using software developed at the German Aerospace Center, Berlin. Whereby only object points are used that have a smaller error than a threshold value. References: [1] Malin, M. C. et al., 2007, JGR 112, doi:10.1029/2006JE002808 [2] Broxton, M. J. et al

  1. Terrain aided navigation for autonomous underwater vehicles with coarse maps

    NASA Astrophysics Data System (ADS)

    Zhou, Ling; Cheng, Xianghong; Zhu, Yixian

    2016-09-01

    Terrain aided navigation (TAN) is a form of geophysical localization technique for autonomous underwater vehicles (AUVs) operating in GPS-denied environments. TAN performance on sensor-rich AUVs has been evaluated in sea trials. However, many challenges remain before TAN can be successfully implemented on sensor-limited AUVs, especially with coarse maps. To improve TAN performance over coarse maps, a Gaussian process (GP) is proposed for the modeling of bathymetric terrain and integrated into the particle filter (GP-PF). GP is applied to provide not only the bathymetric value prediction through learning a set of bathymetric data from coarse maps but also the variance of the prediction. As a measurement update, calculated on bathymetric deviation is performed through the PF to obtain absolute and bounded positioning accuracy. Through the analysis of TAN performance on experimental data for two different terrains with map resolutions of 10-50 m, both the ability of the proposed model to represent the actual bathymetric terrain with accuracy and the effect of the GP-PF for TAN on sensor-limited systems in suited terrain are demonstrated. The experiment results further verify that there is an inverse relationship between the coarseness of the map and the overall TAN accuracy in rough terrains, but there is hardly any relationship between them in relatively flat terrains.

  2. Terrain aided navigation for autonomous underwater vehicles with coarse maps

    NASA Astrophysics Data System (ADS)

    Zhou, Ling; Cheng, Xianghong; Zhu, Yixian

    2016-09-01

    Terrain aided navigation (TAN) is a form of geophysical localization technique for autonomous underwater vehicles (AUVs) operating in GPS-denied environments. TAN performance on sensor-rich AUVs has been evaluated in sea trials. However, many challenges remain before TAN can be successfully implemented on sensor-limited AUVs, especially with coarse maps. To improve TAN performance over coarse maps, a Gaussian process (GP) is proposed for the modeling of bathymetric terrain and integrated into the particle filter (GP-PF). GP is applied to provide not only the bathymetric value prediction through learning a set of bathymetric data from coarse maps but also the variance of the prediction. As a measurement update, calculated on bathymetric deviation is performed through the PF to obtain absolute and bounded positioning accuracy. Through the analysis of TAN performance on experimental data for two different terrains with map resolutions of 10–50 m, both the ability of the proposed model to represent the actual bathymetric terrain with accuracy and the effect of the GP-PF for TAN on sensor-limited systems in suited terrain are demonstrated. The experiment results further verify that there is an inverse relationship between the coarseness of the map and the overall TAN accuracy in rough terrains, but there is hardly any relationship between them in relatively flat terrains.

  3. Format for Interchange and Display of 3D Terrain Data

    NASA Technical Reports Server (NTRS)

    Backes, Paul; Powell, Mark; Vona, Marsette; Norris, Jeffrey; Morrison, Jack

    2004-01-01

    Visible Scalable Terrain (ViSTa) is a software format for production, interchange, and display of three-dimensional (3D) terrain data acquired by stereoscopic cameras of robotic vision systems. ViSTa is designed to support scalability of data, accuracy of displayed terrain images, and optimal utilization of computational resources. In a ViSTa file, an area of terrain is represented, at one or more levels of detail, by coordinates of isolated points and/or vertices of triangles derived from a texture map that, in turn, is derived from original terrain images. Unlike prior terrain-image software formats, ViSTa includes provisions to ensure accuracy of texture coordinates. Whereas many such formats are based on 2.5-dimensional terrain models and impose additional regularity constraints on data, ViSTa is based on a 3D model without regularity constraints. Whereas many prior formats require external data for specifying image-data coordinate systems, ViSTa provides for the inclusion of coordinate-system data within data files. ViSTa admits highspeed loading and display within a Java program. ViSTa is designed to minimize file sizes and maximize compressibility and to support straightforward reduction of resolution to reduce file size for Internet-based distribution.

  4. Synthetic vision helicopter flights using high resolution LIDAR terrain data

    NASA Astrophysics Data System (ADS)

    Sindlinger, A.; Meuter, M.; Barraci, N.; Güttler, M.; Klingauf, U.; Schiefele, J.; Howland, D.

    2006-05-01

    Helicopters are widely used for operations close to terrain such as rescue missions; therefore all-weather capabilities are highly desired. To minimize or even avoid the risk of collision with terrain and obstacles, Synthetic Vision Systems (SVS) could be used to increase situational awareness. In order to demonstrate this, helicopter flights have been performed in the area of Zurich, Switzerland A major component of an SVS is the three-dimensional (3D) depiction of terrain data, usually presented on the primary flight display (PFD). The degree of usability in low level flight applications is a function of the terrain data quality. Today's most precise, large scale terrain data are derived from airborne laser scanning technologies such as LIDAR (light detection and ranging). A LIDAR dataset provided by Swissphoto AG, Zurich with a resolution of 1m was used. The depiction of high resolution terrain data consisting of 1 million elevation posts per square kilometer on a laptop in an appropriate area around the helicopter is challenging. To facilitate the depiction of the high resolution terrain data, it was triangulated applying a 1.5m error margin making it possible to depict an area of 5x5 square kilometer around the helicopter. To position the camera correctly in the virtual scene the SVS had to be supplied with accurate navigation data. Highly flexible and portable measurement equipment which easily could be used in most aircrafts was designed. Demonstration flights were successfully executed in September, October 2005 in the Swiss Alps departing from Zurich.

  5. Self-Supervised Learning of Terrain Traversability from Proprioceptive Sensors

    NASA Technical Reports Server (NTRS)

    Bajracharya, Max; Howard, Andrew B.; Matthies, Larry H.

    2009-01-01

    Robust and reliable autonomous navigation in unstructured, off-road terrain is a critical element in making unmanned ground vehicles a reality. Existing approaches tend to rely on evaluating the traversability of terrain based on fixed parameters obtained via testing in specific environments. This results in a system that handles the terrain well that it trained in, but is unable to process terrain outside its test parameters. An adaptive system does not take the place of training, but supplements it. Whereas training imprints certain environments, an adaptive system would imprint terrain elements and the interactions amongst them, and allow the vehicle to build a map of local elements using proprioceptive sensors. Such sensors can include velocity, wheel slippage, bumper hits, and accelerometers. Data obtained by the sensors can be compared to observations from ranging sensors such as cameras and LADAR (laser detection and ranging) in order to adapt to any kind of terrain. In this way, it could sample its surroundings not only to create a map of clear space, but also of what kind of space it is and its composition. By having a set of building blocks consisting of terrain features, a vehicle can adapt to terrain that it has never seen before, and thus be robust to a changing environment. New observations could be added to its library, enabling it to infer terrain types that it wasn't trained on. This would be very useful in alien environments, where many of the physical features are known, but some are not. For example, a seemingly flat, hard plain could actually be soft sand, and the vehicle would sense the sand and avoid it automatically.

  6. Mobile robots traversability awareness based on terrain visual sensory data fusion

    NASA Astrophysics Data System (ADS)

    Shirkhodaie, Amir

    2007-04-01

    In this paper, we have presented methods that significantly improve the robot awareness of its terrain traversability conditions. The terrain traversability awareness is achieved by association of terrain image appearances from different poses and fusion of extracted information from multimodality imaging and range sensor data for localization and clustering environment landmarks. Initially, we describe methods for extraction of salient features of the terrain for the purpose of landmarks registration from two or more images taken from different via points along the trajectory path of the robot. The method of image registration is applied as a means of overlaying (two or more) of the same terrain scene at different viewpoints. The registration geometrically aligns salient landmarks of two images (the reference and sensed images). A Similarity matching techniques is proposed for matching the terrain salient landmarks. Secondly, we present three terrain classifier models based on rule-based, supervised neural network, and fuzzy logic for classification of terrain condition under uncertainty and mapping the robot's terrain perception to apt traversability measures. This paper addresses the technical challenges and navigational skill requirements of mobile robots for traversability path planning in natural terrain environments similar to Mars surface terrains. We have described different methods for detection of salient terrain features based on imaging texture analysis techniques. We have also presented three competing techniques for terrain traversability assessment of mobile robots navigating in unstructured natural terrain environments. These three techniques include: a rule-based terrain classifier, a neural network-based terrain classifier, and a fuzzy-logic terrain classifier. Each proposed terrain classifier divides a region of natural terrain into finite sub-terrain regions and classifies terrain condition exclusively within each sub-terrain region based on

  7. Perception, planning, and control for walking on rugged terrain

    NASA Technical Reports Server (NTRS)

    Simmons, Reid; Krotkov, Eric

    1991-01-01

    The CMU Planetary Rover project is developing a six-legged walking robot capable of autonomously navigating, exploring, and acquiring samples in rugged, unknown environments. To gain experience with the problems involved in walking on rugged terrain, a full-scale prototype leg was built and mounted on a carriage that rolls along overhead rails. Issues addressed in developing the software system to autonomously walk the leg through rugged terrain are described. In particular, the insights gained into perceiving and modeling rugged terrain, controlling the legged mechanism, interacting with the ground, choosing safe yet effective footfalls, and planning efficient leg moves through space are described.

  8. Sinkhole structure imaging in covered Karst terrain

    NASA Astrophysics Data System (ADS)

    Kruse, S.; Grasmueck, M.; Weiss, M.; Viggiano, D.

    2006-08-01

    Ground penetrating radar (GPR) and resistivity techniques have been widely used to map the locations of sinkholes in covered karst terrain. To determine whether a sinkhole is a likely preferential conduit for groundwater flow, however, requires higher-resolution imaging than that used in conventional sinkhole mapping surveys. Field observations combined with simulated surveys for a 15-m diameter 3-m deep sinkhole in west-central Florida are used to assess the resolution of GPR and resistivity surveys targeting the semiconfining unit that floors the sinkhole depression. 2D resistivity surveys clearly show the central depression as well as resistivity contrasts between the cover sediments within and outside of the sinkhole, but are inadequate for resolving breaches in the semiconfining unit or underlying conduits. A 3D GPR survey resolves vertical structure on the order of tens of centimeters within the semiconfining unit, as well as indicators of conduits that extend several meters beneath the central depression. 3D GPR thus holds promise for imaging hydrologically significant features of sinkholes.

  9. Cratering and Grooved Terrain on Ganymede

    NASA Technical Reports Server (NTRS)

    1979-01-01

    This color picture as acquired by Voyager 1 during its approach to Ganymede on Monday afternoon (the 5th of March). At ranges between about 230 to 250 thousand km. The image shows detail on the surface with a resolution of four and a half km. This picture is just south of PIA001515 (P21161) and shows more craters. It also shows the two distinctive types of terrain found by Voyager, the darker ungrooved regions and the lighter areas which show the grooves or fractures in abundance. The most striking features are the bright ray craters which havE a distinctly 'bluer' color appearing white against the redder background. Ganymede's surface is known to contain large amounts of surface ice and it appears that these relatively young craters have spread bright fresh ice materials over the surface. Likewise, the lighter color and reflectivity of the grooved areas suggests that here too, there is cleaner ice. We see ray craters with all sizes of ray patterns, ranging from extensive systems of the crater in the northern part of this picture, which has rays at least 300-500 kilometers long, down to craters which have only faint remnants of bright ejecta patterns. This variation suggests that, as on the Moon, there are processes which act to darken ray material, probably 'gardening' by micrometeoroid impact. JPL manages and controls the Voyager project for NASA's Office of Space Science.

  10. Ultramaneuverable steering control algorithms for terrain transitions

    NASA Astrophysics Data System (ADS)

    Torrie, Mel W.; Koch, Ralf; Bahl, Vikas; Cripps, Don

    1999-07-01

    The Center for Self-Organizing and Intelligent Systems has built several vehicles with ultra-maneuverable steering capability. Each drive wheel on the vehicle can be independently set at any angle with respect to the vehicle body and the vehicles can rotate or translate in any direction. The vehicles are expected to operate on a wide range of terrain surfaces and problems arise in effectively controlling changes in wheel steering angles as the vehicle transitions from one extreme running surface to another. Controllers developed for smooth surfaces may not perform well on rough or 'sticky' surfaces and vice versa. The approach presented involves the development of a model of the steering motor with the static and viscous friction of the steering motor load included. The model parameters are then identified through a series of environmental tests using a vehicle wheel assembly and the model thus obtained is used for control law development. Four different robust controllers were developed and evaluated through simulation and vehicle testing. The findings of this development will be presented.

  11. Targeting a Hematite-rich Terrain

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image shows the abundance and location of the mineral grey hematite at the Mars Exploration Rover Opportunity's landing site, Meridiani Planum, Mars. Opportunity is targeted to land somewhere inside the oval, approximately 71 kilometers (45 miles) long, on January 24, 2004 Pacific Standard Time. The background surface image of Meridiani Planum is a mosaic of daytime infrared images acquired by the thermal emission imaging system instrument on NASA's Mars Odyssey Orbiter. Superimposed on this image mosaic is a rainbow-colored map showing the abundance and location of grey hematite, as mapped by the thermal emission spectrometer on NASA's Mars Global Surveyor orbiter. Red and yellow indicates higher concentrations, whereas green and blue areas denote lower levels. On Earth, grey hematite is an iron oxide mineral that typically forms in the presence of liquid water. The rover Opportunity will study the martian terrain to determine whether liquid water was present in the past when rocks were being formed, and ultimately will address whether that past environment was favorable for life.

  12. Inversion of topography in Martian highland terrains

    SciTech Connect

    De Hon, R.A.

    1985-01-01

    Ring furrows are flat-floored trenches, circulate in plan view, forming rings 7 to 50 km in diameter. Typically, ring furrows, which are 0.5 km deep and 2 to 10 km wide, surround a central, flat-topped, circular mesa or plateau. The central plateau is about the same elevation or lower than the plain outside the ring. Ring furrows are unique features of the dissected martian uplands. Related landforms range from ring furrows with fractured central plateaus to circular mesas without encircling moats. Ring furrows are superposed on many types of materials, but they are most common cratered plateau-type materials that are interpreted as volcanic flow material overlying ancient cratered terrain. The ring shape and size suggest that they are related to craters partially buried by lava flows. Ring furrows were formed by preferential removal of exposed rims of partially buried craters. Evidence of overland flow of water is lacking except within the channels. Ground ice decay and sapping followed by fluvial erosion are responsible for removal of the less resistant rim materials. Thus, differential erosion has caused a reversal of topography in which the originally elevated rim is reduced to negative relief.

  13. Preventing injuries from all-terrain vehicles.

    PubMed

    Yanchar, Natalie L

    2012-11-01

    All-terrain vehicles (ATVs) are widely used in Canada for recreation, transportation and occupations such as farming. As motorized vehicles, they can be especially dangerous when used by children and young adolescents who lack the knowledge, physical size, strength, and cognitive and motor skills to operate them safely. The magnitude of injury risk to young riders is reflected in explicit vehicle manual warnings and the warning labels on current models, and evidenced by the significant number of paediatric hospitalizations and deaths due to ATV-related trauma. However, helmet use is far from universal among youth operators, and unsafe riding behaviours, such as driving unsupervised and/or driving with passengers, remain common. Despite industry warnings and public education that emphasize the importance of safety behaviours and the risks of significant injury to children and youth, ATV-related injuries and fatalities continue to occur. Until measures are taken that clearly effect substantial reductions in these injuries, restricting ridership by young operators, especially those younger than 16 years of age, is critical to reducing the burden of ATV-related trauma in children and youth. This document replaces a previous Canadian Paediatric Society position statement published in 2004.

  14. Comparison of ArcToolbox and Terrain Tiles processing procedures for inundation mapping in mountainous terrain.

    PubMed

    Darnell, Andrew; Wise, Richard; Quaranta, John

    2013-01-01

    Floodplain management consists of efforts to reduce flood damage to critical infrastructure and to protect the life and health of individuals from flooding. A major component of this effort is the monitoring of flood control structures such as dams because the potential failure of these structures may have catastrophic consequences. To prepare for these threats, engineers use inundation maps that illustrate the flood resulting from high river stages. To create the maps, the structure and river systems are modeled using engineering software programs, and hydrologic events are used to simulate the conditions leading to the failure of the structure. The output data are then exported to other software programs for the creation of inundation maps. Although the computer programs for this process have been established, the processing procedures vary and yield inconsistent results. Thus, these processing methods need to be examined to determine the functionality of each in floodplain management practices. The main goal of this article is to present the development of a more integrated, accurate, and precise graphical interface tool for interpretation by emergency managers and floodplain engineers. To accomplish this purpose, a potential dam failure was simulated and analyzed for a candidate river system using two processing methods: ArcToolbox and Terrain Tiles. The research involved performing a comparison of the outputs, which revealed that both procedures yielded similar inundations for single river reaches. However, the results indicated key differences when examining outputs for large river systems. On the basis of criteria involving the hydrologic accuracy and effects on infrastructure, the Terrain Tiles inundation surpassed the ArcToolbox inundation in terms of following topography and depicting flow rates and flood extents at confluences, bends, and tributary streams. Thus, the Terrain Tiles procedure is a more accurate representation of flood extents for use by

  15. Error detection and rectification in digital terrain models

    NASA Technical Reports Server (NTRS)

    Hannah, M. J.

    1979-01-01

    Digital terrain models produced by computer correlation of stereo images are likely to contain occasional gross errors in terrain elevation. These errors typically result from having mismatched sub-areas of the two images, a problem which can occur for a variety of image- and terrain-related reasons. Such elevation errors produce undesirable effects when the models are further processed, and should be detected and corrected as early in the processing as possible. Algorithms have been developed to detect and correct errors in digital terrain models. These algorithms focus on the use of constraints on both the allowable slope and the allowable change in slope in local areas around each point. Relaxation-like techniques are employed in the iteration of the detection and correction phases to obtain best results.

  16. AirMSPI PODEX BigSur Terrain Images

    Atmospheric Science Data Center

    2013-12-13

    ... from the PODEX 2013 Campaign   Big Sur target (Big Sur, California) 02/03/2013 Terrain-projected   Select ...   Version number   For more information, see the Data Product Specifications (DPS)   ...

  17. Lunar terrain mapping and relative-roughness analysis

    NASA Technical Reports Server (NTRS)

    Rowan, L. C.; Mccauley, J. F.; Holm, E. A.

    1971-01-01

    Terrain maps of the equatorial zone were prepared at scales of 1:2,000,000 and 1:1,000,000 to classify lunar terrain with respect to roughness and to provide a basis for selecting sites for Surveyor and Apollo landings, as well as for Ranger and Lunar Orbiter photographs. Lunar terrain was described by qualitative and quantitative methods and divided into four fundamental classes: maria, terrae, craters, and linear features. Some 35 subdivisions were defined and mapped throughout the equatorial zone, and, in addition, most of the map units were illustrated by photographs. The terrain types were analyzed quantitatively to characterize and order their relative roughness characteristics. For some morphologically homogeneous mare areas, relative roughness can be extrapolated to the large scales from measurements at small scales.

  18. Comparison of Digital Terrain Models Derived Using Different Techniques

    NASA Astrophysics Data System (ADS)

    Della-Giustina, D. N.; Kinney Spano, E. K.; Chojnacki, M.; Sutton, S.

    2015-06-01

    In preparation for the OSIRIS-REx Sample Return Mission we examine newly available computer vision and traditional photogrammetry tools capable of producing digital terrain models (DTMs) from stereo imagery.

  19. Cross-coupled control for all-terrain rovers.

    PubMed

    Reina, Giulio

    2013-01-01

    Mobile robots are increasingly being used in challenging outdoor environments for applications that include construction, mining, agriculture, military and planetary exploration. In order to accomplish the planned task, it is critical that the motion control system ensure accuracy and robustness. The achievement of high performance on rough terrain is tightly connected with the minimization of vehicle-terrain dynamics effects such as slipping and skidding. This paper presents a cross-coupled controller for a 4-wheel-drive/4-wheel-steer robot, which optimizes the wheel motors' control algorithm to reduce synchronization errors that would otherwise result in wheel slip with conventional controllers. Experimental results, obtained with an all-terrain rover operating on agricultural terrain, are presented to validate the system. It is shown that the proposed approach is effective in reducing slippage and vehicle posture errors. PMID:23299625

  20. Rovers for intelligent, agile traverse of challenging terrain

    NASA Technical Reports Server (NTRS)

    Schenker, P.; Huntsberger, T.; Pirjanian, P.; Dubowsky, S.; Iagnemma, K.; Sujan, V.

    2003-01-01

    Planetary surface mobility has to date been limited to benign locations. If rover systems could be developed for more challenging terrain, e.g., sloped and irregularly feathered areas, then planetary science opportunities would be greatly expanded.

  1. 12. VIEW OF ROAD ACROSS RELATIVELY FLAT TERRAIN (SECTION E), ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. VIEW OF ROAD ACROSS RELATIVELY FLAT TERRAIN (SECTION E), RECENTLY CLEARED OF SMALL TREES AND BRUSH BY THE KOOTENAI NATIONAL FOREST - Troy-Libby Highway, Between Troy & Libby, Troy, Lincoln County, MT

  2. Cross-coupled control for all-terrain rovers.

    PubMed

    Reina, Giulio

    2013-01-08

    Mobile robots are increasingly being used in challenging outdoor environments for applications that include construction, mining, agriculture, military and planetary exploration. In order to accomplish the planned task, it is critical that the motion control system ensure accuracy and robustness. The achievement of high performance on rough terrain is tightly connected with the minimization of vehicle-terrain dynamics effects such as slipping and skidding. This paper presents a cross-coupled controller for a 4-wheel-drive/4-wheel-steer robot, which optimizes the wheel motors' control algorithm to reduce synchronization errors that would otherwise result in wheel slip with conventional controllers. Experimental results, obtained with an all-terrain rover operating on agricultural terrain, are presented to validate the system. It is shown that the proposed approach is effective in reducing slippage and vehicle posture errors.

  3. Spatial and temporal variability of hyperspectral signatures of terrain

    NASA Astrophysics Data System (ADS)

    Jones, K. F.; Perovich, D. K.; Koenig, G. G.

    2008-04-01

    Electromagnetic signatures of terrain exhibit significant spatial heterogeneity on a range of scales as well as considerable temporal variability. A statistical characterization of the spatial heterogeneity and spatial scaling algorithms of terrain electromagnetic signatures are required to extrapolate measurements to larger scales. Basic terrain elements including bare soil, grass, deciduous, and coniferous trees were studied in a quasi-laboratory setting using instrumented test sites in Hanover, NH and Yuma, AZ. Observations were made using a visible and near infrared spectroradiometer (350 - 2500 nm) and hyperspectral camera (400 - 1100 nm). Results are reported illustrating: i) several difference scenes; ii) a terrain scene time series sampled over an annual cycle; and iii) the detection of artifacts in scenes. A principal component analysis indicated that the first three principal components typically explained between 90 and 99% of the variance of the 30 to 40-channel hyperspectral images. Higher order principal components of hyperspectral images are useful for detecting artifacts in scenes.

  4. Cross-Coupled Control for All-Terrain Rovers

    PubMed Central

    Reina, Giulio

    2013-01-01

    Mobile robots are increasingly being used in challenging outdoor environments for applications that include construction, mining, agriculture, military and planetary exploration. In order to accomplish the planned task, it is critical that the motion control system ensure accuracy and robustness. The achievement of high performance on rough terrain is tightly connected with the minimization of vehicle-terrain dynamics effects such as slipping and skidding. This paper presents a cross-coupled controller for a 4-wheel-drive/4-wheel-steer robot, which optimizes the wheel motors' control algorithm to reduce synchronization errors that would otherwise result in wheel slip with conventional controllers. Experimental results, obtained with an all-terrain rover operating on agricultural terrain, are presented to validate the system. It is shown that the proposed approach is effective in reducing slippage and vehicle posture errors. PMID:23299625

  5. VTAC: virtual terrain assisted impact assessment for cyber attacks

    NASA Astrophysics Data System (ADS)

    Argauer, Brian J.; Yang, Shanchieh J.

    2008-03-01

    Overwhelming intrusion alerts have made timely response to network security breaches a difficult task. Correlating alerts to produce a higher level view of intrusion state of a network, thus, becomes an essential element in network defense. This work proposes to analyze correlated or grouped alerts and determine their 'impact' to services and users of the network. A network is modeled as 'virtual terrain' where cyber attacks maneuver. Overlaying correlated attack tracks on virtual terrain exhibits the vulnerabilities exploited by each track and the relationships between them and different network entities. The proposed impact assessment algorithm utilizes the graph-based virtual terrain model and combines assessments of damages caused by the attacks. The combined impact scores allow to identify severely damaged network services and affected users. Several scenarios are examined to demonstrate the uses of the proposed Virtual Terrain Assisted Impact Assessment for Cyber Attacks (VTAC).

  6. Knobby terrain in Northern Arabia Terra

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 25 April 2002) The Science This THEMIS visible image shows a region in northern Arabia Terra near 44o N, 322o W (38o E). Knobby or 'scabby' plains units that mantle and modify a pre-existing cratered surface dominate the unusual landscape in this region. Several large (5-8 km diameter) impact craters seen in the upper left of the image have been extensively modified since their initial formation. The rims of these craters can still be seen, but the ejecta deposits and the surrounding plains have been buried by a layer of material. This mantling layer has itself been modified to produce a pitted, knobby surface. Circular depressions of all sizes, presumably the remnants of impact craters, are filled with smooth deposits. In some places large regions have been covered by this smooth material; an example can be seen in the lower right portion of this image. In many cases the impact craters have been extensively modified prior to their being filled. This modification indicates an erosion process that has removed material from the walls to produce shapes that vary from circular with crisp rims, to circular with no rims, to oblong and elliptical forms, and finally to irregular shapes whose initial circular outline can barely be detected. The slope of the channel at the top of the image has an unusual deposit of material that occurs preferentially on the cold, north-facing slope. Similar deposits are seen frequently at mid-northern and southern latitudes on Mars, and have a characteristic, rounded boundary that typically occurs at approximately the same distance below the ridge crest. It has been suggested that these deposits once draped the entire surface and have since been removed from all but the cold north-facing slopes. The presence and removal of ground ice may play an important role in the formation of this layer, as well as the knobby terrain and unusual features seen in this image. The StoryThere's no way these impact craters are in their original

  7. Improving terrain height estimates from RADARSAT interferometric measurements

    SciTech Connect

    Thompson, P.A.; Eichel, P.H.; Calloway, T.M.

    1998-03-01

    The authors describe two methods of combining two-pass RADAR-SAT interferometric phase maps with existing DTED (digital terrain elevation data) to produce improved terrain height estimates. The first is a least-squares estimation procedure that fits the unwrapped phase data to a phase map computed from the DTED. The second is a filtering technique that combines the interferometric height map with the DTED map based on spatial frequency content. Both methods preserve the high fidelity of the interferometric data.

  8. Terrain intelligence Chita Oblast (U.S.S.R.)

    USGS Publications Warehouse

    ,

    1943-01-01

    The following folio of maps and explanatory tables outlines the principal terrain features of the Chita Oblast.  Each map and table is devoted to a specialized set of problems; together they cover such subjects as terrain appreciations, rivers, surface-water and ground-water supplies, construction materials, fuels, suitability for temporary roads and airfields, mineral resources, and geology.  These maps and data were complied by the United States Geological Survey.

  9. Mars South Polar Cap 'Fingerprint' Terrain

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This picture is illuminated by sunlight from the upper left.

    Some portions of the martian south polar residual cap have long, somewhat curved troughs instead of circular pits. These appear to form in a layer of material that may be different than that in which 'swiss cheese' circles and pits form, and none of these features has any analog in the north polar cap or elsewhere on Mars. This picture shows the 'fingerprint' terrain as a series of long, narrow depressions considered to have formed by collapse and widening by sublimation of ice. Unlike the north polar cap, the south polar region stays cold enough in summer to retain frozen carbon dioxide. Viking Orbiter observations during the late 1970s showed that very little water vapor comes off the south polar cap during summer, indicating that any frozen water that might be there remains solid throughout the year.

    This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image was obtained in early southern spring on August 4, 1999. It shows an area 3 x 5 kilometers (1.9 x 3.1 miles) at a resolution of about 7.3 meters (24 ft) per pixel. Located near 86.0oS, 53.9oW.

    Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

  10. Terrain on Europa under Changing Lighting Conditions

    NASA Technical Reports Server (NTRS)

    1997-01-01

    These images obtained by the Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft show the same region of Europa under different lighting conditions. The upper image was obtained on June 28th, 1996 during Galileo's first orbit around Jupiter under 'high-sun' conditions -- the equivalent of taking a picture from a high altitude at noon (with the sun directly overhead). Note that albedo (light/dark) features are emphasized. Compare this to the lower image containing a higher-resolution inset. This (inset) image was taken on November 6th, 1996 during the spacecraft's third orbit under 'low-sun' illumination -- the equivalent of taking a picture from a high altitude at sunrise or sunset. Note that in this image the albedo features are not readily apparent. Instead, the topography of the terrain is emphasized. Planetary geologists use information from images acquired under a variety of lighting conditions to identify different types of structures and interpret how they formed. Note that the bright linear features in the upper image are seen to be ridges in the lower image. The circular feature on the right side of both images, Cilix, is approximately 25 kilometers (15 miles) across.

    The area seen in the upper image is 312 kilometers (187 miles) by 570 kilometers (342 miles) across; the area covered by the inset is 36 kilometers (22 miles) by 315 kilometers (190 miles) across. Both of these images are centered near 2 South latitude, 185 West longitude. North is to the top of the frames.

    The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

  11. High fidelity terrain models and geospatial datasets for use in distributed test environments

    NASA Astrophysics Data System (ADS)

    Snyder, Gerard; Gorkavyi, Nick; Lashlee, David; Lorenzo, Max

    2005-05-01

    Distributed testing of a system of systems such is critical to successful development and fielding. Developmental and operational test planning, mission rehearsal, and modeling and simulation of distributed test events requires rapid generation of high-fidelity synthetic environments and geospatial databases that allow efficient transmission and portrayal over network-centric architectures and low-bandwidth communications networks. This paper describes an initiative lead by the U.S. Army Developmental Test Center to rapidly construct digital terrain and surface models using remote sensing data. The authors present methods and techniques used to generate Digital Terrain Elevation Data (DTED) Level 5 or better digital terrain models, surface object databases using Three-Dimensional (3-D) data from airborne Light Detection and Ranging (LIDAR) sensors, and mathematical operations to describe complex geospatial data objects and 3-D topology in highly-compact manners. Currently, units-of-action undergo testing within a defined Common Operating Area (COA) at a training range or proving ground. In coming years, distributed testing, with simulated scenes added to the participating systems, will occur at multiple COAs located at different test facilities. Consistent construction is required for these synthetic environments or scenes for the different facilities. The authors will present trade study results with recommendations for a uniform set of data collection requirements.

  12. Learned navigation in unknown terrains: A retraction method

    NASA Technical Reports Server (NTRS)

    Rao, Nageswara S. V.; Stoltzfus, N.; Iyengar, S. Sitharama

    1989-01-01

    The problem of learned navigation of a circular robot R, of radius delta (is greater than or equal to 0), through a terrain whose model is not a-priori known is considered. Two-dimensional finite-sized terrains populated by an unknown (but, finite) number of simple polygonal obstacles are also considered. The number and locations of the vertices of each obstacle are unknown to R. R is equipped with a sensor system that detects all vertices and edges that are visible from its present location. In this context two problems are covered. In the visit problem, the robot is required to visit a sequence of destination points, and in the terrain model acquisition problem, the robot is required to acquire the complete model of the terrain. An algorithmic framework is presented for solving these two problems using a retraction of the freespace onto the Voronoi diagram of the terrain. Algorithms are then presented to solve the visit problem and the terrain model acquisition problem.

  13. Vegetation-terrain feature relationships in southeast Arizona

    NASA Technical Reports Server (NTRS)

    Schrumpf, B. J. (Principal Investigator); Mouat, D. A.

    1972-01-01

    There are no author-identified significant results in this report. Studies of relationships of vegetation distribution to geomorphic characteristics of the landscape and of plant phenological patterns to vegetation identification of satellite imagery indicate that there exists positive relationships between certain plant species and certain terrain features. Not all species were found to exhibit positive relationships with all terrain feature variables, but enough positive relationships seem to exist to indicate that terrain feature variable-vegetation relationship studies have a definite place in plant ecological investigations. Even more importantly, the vegetation groups examined appeared to be successfully discriminated by the terrain feature variables. This would seem to indicate that spatial interpretations of vegetation groups may be possible. While vegetational distributions aren't determined by terrain feature differences, terrain features do mirror factors which directly influence vegetational response and hence distribution. As a result, those environmental features which can be readily and rapidly ascertained on relatively small-scale imagery may prove to be valuable indicators of vegetation distribution.

  14. Strike-Slip Faulting Processes on Ganymede: Global Morphological Mapping and Structural Interpretation of Grooved and Transitional Terrains

    NASA Astrophysics Data System (ADS)

    Burkhard, L. M.; Cameron, M. E.; Smith-Konter, B. R.; Seifert, F.; Pappalardo, R. T.; Collins, G. C.

    2015-12-01

    Ganymede's fractured surface reveals many large-scale, morphologically distinct regions of inferred distributed shear and strike-slip faulting that may be important to the structural development of its surface and in the transition from dark to light (grooved) materials. To better understand the role of strike-slip tectonism in shaping Ganymede's complex icy surface, we perform a detailed mapping of key examples of strike-slip morphologies (i.e., en echelon structures, strike-slip duplexes, laterally offset pre-existing features, and possible strained craters) from Galileo and Voyager images. We focus on complex structures associated with grooved terrain (e.g. Nun Sulcus, Dardanus Sulcus, Tiamat Sulcus, and Arbela Sulcus) and terrains transitional from dark to light terrain (e.g. the boundary between Nippur Sulcus and Marius Regio, including Byblus Sulcus and Philus Sulcus). Detailed structural interpretations suggest strong evidence of strike-slip faulting in some regions (i.e., Nun and Dardanus Sulcus); however, further investigation of additional strike-slip structures is required of less convincing regions (i.e., Byblus Sulcus). Where applicable, these results are synthesized into a global database representing an inferred sense of shear for many of Ganymede's fractures. Moreover, when combined with existing observations of extensional features, these results help to narrow down the range of possible principal stress directions that could have acted at the regional or global scale to produce grooved terrain on Ganymede.

  15. A Method for Estimating the Hydrologic Input from Fog in Mountainous Terrain.

    NASA Astrophysics Data System (ADS)

    Walmsley, John L.; Schemenauer, Robert S.; Bridgman, Howard A.

    1996-12-01

    A methodology for obtaining estimates of the spatial distribution of fog water volume collected by a tree canopy in complex terrain is described. The method includes assumptions about the shape and spacing of the trees, their fog water collection efficiency, the fog frequency, and the vertical rate of change of the liquid water content (LWC) within ground-based clouds.The method was applied to a 655-km2 area surrounding Roundtop Mountain, Quebec, Canada, during a carefully selected sample period from the summer of 1993. Field measurements of fog water volume were used to estimate the cloud-base height and the rate of change of the LWC with height. Topographic data were used both as a forcing function in the wind flow model and as a means of defining the three-dimensional geometry for deposition calculations. The goal is the development of a simple model that can be used over large geographic areas.Results of the application are presented over various domains ranging from 2 to 164 Km2 in size. Spatial variations in the wind velocity field just above the canopy were found to be related to the main terrain features (summits, ridges, and valleys). The fog water deposition rate was specified as a linear function both of terrain height above cloud base and of wind speed. Near the summit of Roundtop Mountain, variations in terrain height were more pronounced than those of treetop wind speeds. Spatial patterns of fog water deposition, therefore, strongly reflected the pattern of topographic contours, with some modifications being apparent due to spatial variations in wind speed. Calculated deposition values ranged up to 0.69 mm h1 and were found to be typical of measured values in the literature.

  16. Terrain correction program for gravity data: user's guide and documentation for Rev. 0)

    SciTech Connect

    Serpa, L.F.; Cook, K.L.

    1981-01-01

    Terrain accesses terrain data stored on a magnetic tape to create terrain maps digitized at 30 sec., 1 min., and 3 min. of arc intervals of the area to be used for the terrain corrections. This report presents a program description and a sample execution of the program. (ACR)

  17. 47 CFR 24.53 - Calculation of height above average terrain (HAAT).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Calculation of height above average terrain... average terrain (HAAT). (a) HAAT is determined by subtracting average terrain elevation from antenna height above mean sea level. (b) Average terrain elevation shall be calculated using elevation data...

  18. 47 CFR 24.53 - Calculation of height above average terrain (HAAT).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Calculation of height above average terrain... average terrain (HAAT). (a) HAAT is determined by subtracting average terrain elevation from antenna height above mean sea level. (b) Average terrain elevation shall be calculated using elevation data...

  19. 47 CFR 24.53 - Calculation of height above average terrain (HAAT).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Calculation of height above average terrain... average terrain (HAAT). (a) HAAT is determined by subtracting average terrain elevation from antenna height above mean sea level. (b) Average terrain elevation shall be calculated using elevation data...

  20. 47 CFR 24.53 - Calculation of height above average terrain (HAAT).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Calculation of height above average terrain... average terrain (HAAT). (a) HAAT is determined by subtracting average terrain elevation from antenna height above mean sea level. (b) Average terrain elevation shall be calculated using elevation data...

  1. 47 CFR 24.53 - Calculation of height above average terrain (HAAT).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Calculation of height above average terrain... average terrain (HAAT). (a) HAAT is determined by subtracting average terrain elevation from antenna height above mean sea level. (b) Average terrain elevation shall be calculated using elevation data...

  2. Application of the Deformation Information System for automated analysis and mapping of mining terrain deformations - case study from SW Poland

    NASA Astrophysics Data System (ADS)

    Blachowski, Jan; Grzempowski, Piotr; Milczarek, Wojciech; Nowacka, Anna

    2015-04-01

    Monitoring, mapping and modelling of mining induced terrain deformations are important tasks for quantifying and minimising threats that arise from underground extraction of useful minerals and affect surface infrastructure, human safety, the environment and security of the mining operation itself. The number of methods and techniques used for monitoring and analysis of mining terrain deformations is wide and expanding with the progress in geographical information technologies. These include for example: terrestrial geodetic measurements, Global Navigation Satellite Systems, remote sensing, GIS based modelling and spatial statistics, finite element method modelling, geological modelling, empirical modelling using e.g. the Knothe theory, artificial neural networks, fuzzy logic calculations and other. The presentation shows the results of numerical modelling and mapping of mining terrain deformations for two cases of underground mining sites in SW Poland, hard coal one (abandoned) and copper ore (active) using the functionalities of the Deformation Information System (DIS) (Blachowski et al, 2014 @ http://meetingorganizer.copernicus.org/EGU2014/EGU2014-7949.pdf). The functionalities of the spatial data modelling module of DIS have been presented and its applications in modelling, mapping and visualising mining terrain deformations based on processing of measurement data (geodetic and GNSS) for these two cases have been characterised and compared. These include, self-developed and implemented in DIS, automation procedures for calculating mining terrain subsidence with different interpolation techniques, calculation of other mining deformation parameters (i.e. tilt, horizontal displacement, horizontal strain and curvature), as well as mapping mining terrain categories based on classification of the values of these parameters as used in Poland. Acknowledgments. This work has been financed from the National Science Centre Project "Development of a numerical method of

  3. Integrated terrain mapping with digital Landsat images in Queensland, Australia

    USGS Publications Warehouse

    Robinove, Charles Joseph

    1979-01-01

    Mapping with Landsat images usually is done by selecting single types of features, such as soils, vegetation, or rocks, and creating visually interpreted or digitally classified maps of each feature. Individual maps can then be overlaid on or combined with other maps to characterize the terrain. Integrated terrain mapping combines several terrain features into each map unit which, in many cases, is more directly related to uses of the land and to methods of land management than the single features alone. Terrain brightness, as measured by the multispectral scanners in Landsat 1 and 2, represents an integration of reflectance from the terrain features within the scanner's instantaneous field of view and is therefore more correlatable with integrated terrain units than with differentiated ones, such as rocks, soils, and vegetation. A test of the feasibilty of the technique of mapping integrated terrain units was conducted in a part of southwestern Queensland, Australia, in cooperation with scientists of the Queensland Department of Primary Industries. The primary purpose was to test the use of digital classification techniques to create a 'land systems map' usable for grazing land management. A recently published map of 'land systems' in the area (made by aerial photograph interpretation and ground surveys), which are integrated terrain units composed of vegetation, soil, topography, and geomorphic features, was used as a basis for comparison with digitally classified Landsat multispectral images. The land systems, in turn, each have a specific grazing capacity for cattle (expressed in beasts per km 2 ) which is estimated following analysis of both research results and property carrying capacities. Landsat images, in computer-compatible tape form, were first contrast-stretched to increase their visual interpretability, and digitally classified by the parallelepiped method into distinct spectral classes to determine their correspondence to the land systems classes and

  4. Terrain Portrayal for Head-Down Displays Experiment

    NASA Technical Reports Server (NTRS)

    Hughes, Monica F.; Takallu, M. A.

    2002-01-01

    The General Aviation Element of the Aviation Safety Program's Synthetic Vision Systems (SVS) Project is developing technology to eliminate low visibility induced General Aviation (GA) accidents. SVS displays present computer generated 3-dimensional imagery of the surrounding terrain on the Primary Flight Display (PFD) to greatly enhance pilot's situation awareness (SA), reducing or eliminating Controlled Flight into Terrain, as well as Low-Visibility Loss of Control accidents. SVS-conducted research is facilitating development of display concepts that provide the pilot with an unobstructed view of the outside terrain, regardless of weather conditions and time of day. A critical component of SVS displays is the appropriate presentation of terrain to the pilot. An experimental study has been conducted at NASA Langley Research Center (LaRC) to explore and quantify the relationship between the realism of the terrain presentation and resulting enhancements of pilot SA and pilot performance. Composed of complementary simulation and flight test efforts, Terrain Portrayal for Head-Down Displays (TP-HDD) experiments will help researchers evaluate critical terrain portrayal concepts. The experimental effort is to provide data to enable design trades that optimize SVS applications, as well as develop requirements and recommendations to facilitate the certification process. This paper focuses on the experimental set-up and preliminary qualitative results of the TP-HDD simulation experiment. In this experiment a fixed based flight simulator was equipped with various types of Head Down flight displays, ranging from conventional round dials (typical of most GA aircraft) to glass cockpit style PFD's. The variations of the PFD included an assortment of texturing and Digital Elevation Model (DEM) resolution combinations. A test matrix of 10 terrain display configurations (in addition to the baseline displays) were evaluated by 27 pilots of various backgrounds and experience levels

  5. An Efficient Ray-Tracing Method for Determining Terrain Intercepts in EDL Simulations

    NASA Technical Reports Server (NTRS)

    Shidner, Jeremy D.

    2016-01-01

    The calculation of a ray's intercept from an arbitrary point in space to a prescribed surface is a common task in computer simulations. The arbitrary point often represents an object that is moving according to the simulation, while the prescribed surface is fixed in a defined frame. For detailed simulations, this surface becomes complex, taking the form of real-world objects such as mountains, craters or valleys which require more advanced methods to accurately calculate a ray's intercept location. Incorporation of these complex surfaces has commonly been implemented in graphics systems that utilize highly optimized graphics processing units to analyze such features. This paper proposes a simplified method that does not require computationally intensive graphics solutions, but rather an optimized ray-tracing method for an assumed terrain dataset. This approach was developed for the Mars Science Laboratory mission which landed on the complex terrain of Gale Crater. First, this paper begins with a discussion of the simulation used to implement the model and the applicability of finding surface intercepts with respect to atmosphere modeling, altitude determination, radar modeling, and contact forces influencing vehicle dynamics. Next, the derivation and assumptions of the intercept finding method are presented. Key assumptions are noted making the routines specific to only certain types of surface data sets that are equidistantly spaced in longitude and latitude. The derivation of the method relies on ray-tracing, requiring discussion on the formulation of the ray with respect to the terrain datasets. Further discussion includes techniques for ray initialization in order to optimize the intercept search. Then, the model implementation for various new applications in the simulation are demonstrated. Finally, a validation of the accuracy is presented along with the corresponding data sets used in the validation. A performance summary of the method will be shown using

  6. Biomechanics and energetics of walking on uneven terrain.

    PubMed

    Voloshina, Alexandra S; Kuo, Arthur D; Daley, Monica A; Ferris, Daniel P

    2013-11-01

    Walking on uneven terrain is more energetically costly than walking on smooth ground, but the biomechanical factors that contribute to this increase are unknown. To identify possible factors, we constructed an uneven terrain treadmill that allowed us to record biomechanical, electromyographic and metabolic energetics data from human subjects. We hypothesized that walking on uneven terrain would increase step width and length variability, joint mechanical work and muscle co-activation compared with walking on smooth terrain. We tested healthy subjects (N=11) walking at 1.0 m s(-1), and found that, when walking on uneven terrain with up to 2.5 cm variation, subjects decreased their step length by 4% and did not significantly change their step width, while both step length and width variability increased significantly (22 and 36%, respectively; P<0.05). Uneven terrain walking caused a 28 and 62% increase in positive knee and hip work, respectively, and a 26% greater magnitude of negative knee work (0.0106, 0.1078 and 0.0425 J kg(-1), respectively; P<0.05). Mean muscle activity increased in seven muscles in the lower leg and thigh (P<0.05). These changes caused overall net metabolic energy expenditure to increase by 0.73 W kg(-1) (28%; P<0.0001). Much of that increase could be explained by the increased mechanical work observed at the knee and hip. Greater muscle co-activation could also contribute to increased energetic cost but to unknown degree. The findings provide insight into how lower limb muscles are used differently for natural terrain compared with laboratory conditions.

  7. Use of the ER-2 and IFSAR for digital terrain matrix, difference digital terrain matrix, and vector difference digital terrain matrix collection

    SciTech Connect

    Malliot, H.A.

    1996-10-01

    A national digital terrain matrix (DTM) archive with sub-meter elevation precision and three meter or less post spacing will have numerous commercial government and research uses. The Lockheed Martin Missiles and Space Digital Terrain Elevation Mapping System (DTEMS) will be used to collect a DTM archive with average relative one {sigma} elevation precision of 0.3 meter, average absolute one U elevation precision less than 0.6 meter, and one to three meter post spacing (posting). DTEMS data will satisfy National Map Accuracy Standards (NMAS) contour intervals of one to two meters. DTEMS will also archive orth-rectified digital polarimetric synthetic aperture radar (SAR) imagery with one to three meter resolution. A difference digital terrain matrix (DDTM) is defined as a digital data file containing elevation changes in a DTM. A DDTM archive will be useful for detection and measurement of natural or man made changes in terrain elevation. Using DTEMS to make periodic repeat DTM collections and coherent elevation change detection (CECD) to sense small elevation changes, DTEMS will be capable of resolving elevation changes of a few centimeters. A vector difference digital terrain matrix (VDDTM) is defined as a digital data file containing the X, Y and Z displacements of the ground. Using CECD with a sub-pixel digital image correlation (SPDIC) technique on pairs of DTM`s and radar images collected by DTEMS, it will be possible to measure X and Y ground displacements with resolutions of ten centimeters at posts with spacing of ten meters and measure the elevation (Z) displacement with a resolution of a few centimeters. 8 refs., 6 figs.

  8. Aspects of conducting site investigations in glacial terrain

    SciTech Connect

    Schilling, K.E. )

    1993-03-01

    Much of northern US is mantled by Pleistocene glacial drift consisting of heterogeneous deposits of fine to coarse-textured sediments. Hazardous waste site investigations in glacial settings can often present unique design and implementation considerations. Complex glacial stratigraphy encountered during drilling activities demands flexibility built into work plans to allow for field decisions based on field conditions. Continuous cores should be collected from boreholes on a routine basis for stratigraphic purposes with particular importance assigned to field identification of relative permeabilities of stratigraphic units. Selection of appropriate field screening methodology should be based on site conditions. Utilization of open borehole groundwater sampling is recommended for fine-textured glacial settings where soil gas and well point sampling are ineffective. Installation of boreholes allows for collection of stratigraphic information and enables more surface area exposed beneath the water table for groundwater recharge and sampling. Water level determinations can be made on open boreholes for an initial assessment of the horizontal direction of groundwater flow. Placement of screens for monitoring wells should be based on field determination of likely groundwater flow paths. Nested wells are necessary to define the vertical groundwater flow system at most sites. Evaluation of the vertical flow system can often dominate site investigations in fine-textured glacial terrain. Two case studies from Iowa illustrate the usefulness of incorporating the above considerations in planning and implementing in fine-textured glacial sediments. Field investigations utilizing open borehole groundwater sampling successfully delineated site glacial geology and hydrogeology for determination of the nature and extent of groundwater contamination and better located the horizontal and vertical placement of monitoring wells.

  9. Terrain Portrayal for Head-Down Displays Flight Test

    NASA Technical Reports Server (NTRS)

    Hughes, Monica F.; Glaab, Louis J.

    2003-01-01

    The Synthetic Vision Systems General Aviation (SVS-GA) element of NASA's Aviation Safety Program is developing technology to eliminate low visibility induced General Aviation (GA) accidents through the application of synthetic vision techniques. SVS displays present computer generated 3-dimensional imagery of the surrounding terrain to greatly enhance pilot's situation awareness (SA), reducing or eliminating Controlled Flight into Terrain (CFIT), as well as Low-Visibility Loss of Control (LVLOC) accidents. In addition to substantial safety benefits, SVS displays have many potential operational benefits that can lead to flight in instrument meteorological conditions (IMC) resembling those conducted in visual meteorological conditions (VMC). Potential benefits could include lower landing minimums, more approach options, reduced training time, etc. SVS conducted research will develop display concepts providing the pilot with an unobstructed view of the outside terrain, regardless of weather conditions and time of day. A critical component of SVS displays is the appropriate presentation of terrain to the pilot. The relationship between the realism of the terrain presentation and resulting enhancements of pilot SA and pilot performance has been largely undefined. Comprised of coordinated simulation and flight test efforts, the terrain portrayal for head-down displays (TP-HDD) test series examined the effects of two primary elements of terrain portrayal: variations of digital elevation model (DEM) resolution and terrain texturing. Variations in DEM resolution ranged from sparsely spaced (30 arc-sec/2,953ft) to very closely spaced data (1 arc-sec/98 ft). Variations in texture involved three primary methods: constant color, elevation-based generic, and photo-realistic, along with a secondary depth cue enhancer in the form of a fishnet grid overlay. The TP-HDD test series was designed to provide comprehensive data to enable design trades to optimize all SVS applications, as

  10. Flexible formation configuration for terrain following flight: Formation keeping constraints

    NASA Astrophysics Data System (ADS)

    Latyshev, Simon

    This work suggests a control method for the terrain-following formation motion of a group of communicating autonomous agents. The presented approach centers on defining a suitable set of constraints for formation keeping task that shall be fulfilled while agents are negotiating an unknown terrain toward the predefined goal location. It allows agents to maintain a general geometric formation shape, while allowing each individual formation member freedom of maneuver, required for terrain collision free motion. Formation structure is defined with the use of virtual leader. Formation keeping constraints are defined with plane surfaces, specified relative to position and navigation vector of the virtual leader. Formation navigation and guidance constraints are defined using navigation vectors of formation members and the virtual leader. Alternative designs for the constraints derived with parabolic, cone, and cylindrical surfaces are considered. Formation control is derived using the Udwadia-Kalaba equation, following corresponding approach to the development of control methods for constraint based dynamical systems, including leader-follower systems defined using geometric constraints. Approach to terrain following motion requiring agents to stay within bounds of cylindrical corridor volumes built around their respective navigation vectors is assumed. Individual formation primitives and multi-level, hierarchical, formation structures are considered. Simulations, based on three degrees of freedom nonlinear model of an agent, performed using Mathematica and specifically developed combined Maya-Mathematica modeling and simulation system, demonstrate that a flexible terrain following formation motion is achieved with the presented sets of constraints.

  11. Geomorphic Evolution of Sputnik Planum and Surrounding Terrain

    NASA Astrophysics Data System (ADS)

    Howard, A. D.; Moore, J. M.; White, O. L.; Umurhan, O. M.; Schenk, P.; Beyer, R. A.; McKinnon, W. B.; Singer, K. N.; Spencer, J. R.; Stern, A.; Weaver, H. A., Jr.; Young, L. A.; Ennico Smith, K.; Olkin, C.

    2015-12-01

    The informally-named Sputnik Planum is a vast expanse (about 835 km east-west and 1500 km north-south) of N2, CH4, and CO ices which appears craterless at current resolutions, but which gives evidence of both glacial and convective flow in the ices (Stern and the New Horizons Team, Science, 2015). This ice field is surrounded by uplands of varying morphology from hilly terrain to the northeast, plains of apparent ices interspersed with rough terrain to the east, and textured ice surrounding the mountainous terrain to the southwest. The morphology and composition of this bordering terrain will provide clues to the long-term evolution of Sputnik Planum as higher resolution visual and spectral imaging of this region are returned from the New Horizons spacecraft over the next few months. Interactions between Sputnik Planum and surrounding terrain may have involved glacial erosion and deposition. The geomorphic evolution of this region will be discussed in the context of newly-returned encounter data.

  12. On autonomous terrain model acquistion by a mobile robot

    NASA Technical Reports Server (NTRS)

    Rao, N. S. V.; Iyengar, S. S.; Weisbin, C. R.

    1987-01-01

    The following problem is considered: A point robot is placed in a terrain populated by an unknown number of polyhedral obstacles of varied sizes and locations in two/three dimensions. The robot is equipped with a sensor capable of detecting all the obstacle vertices and edges that are visible from the present location of the robot. The robot is required to autonomously navigate and build the complete terrain model using the sensor information. It is established that the necessary number of scanning operations needed for complete terrain model acquisition by any algorithm that is based on scan from vertices strategy is given by the summation of i = 1 (sup n) N(O sub i)-n and summation of i = 1 (sup n) N(O sub i)-2n in two- and three-dimensional terrains respectively, where O = (O sub 1, O sub 2,....O sub n) set of the obstacles in the terrain, and N(O sub i) is the number of vertices of the obstacle O sub i.

  13. Assessment of antipodal-impact terrains on Mars

    NASA Technical Reports Server (NTRS)

    Williams, David A.; Greeley, Ronald

    1994-01-01

    The regions anitpodal to Mars' three largest impact basins, Hellas, Isidis, and Argyre, were assessed for evidence of impact-induced disrupted terrains. Photogeology and computer modeling using the Simplified Arbitrary Lagrangian Eulerian (SALE) finite element code suggest that such terrains could have been found by the Hellas impact. Maximum antipodal pressures are 1100 MPa for Hellas, 520 MPa for Isidis, and 150 MPa for Argyre. The results suggest that if antipodal fracturing were associated with later volcanism, then Alba Patera may be related to the Hellas event, as proposed by Peterson (1978). Alba Patera is a unique volcano in the solar system, being a shield volcano which emitted large volume lava flows. This volcanism could be the result of the focusing of seismic energy which created a fractured region that served as a volcanic conduit for the future release of large volumes of magma. No disrupted terrain features are observed antipodal to the Isidis or Argyre basins, although some of the old fractures in Noctis Labyrinthus could have originated in response to the Isidis impact, and later have been reactivated by the Tharsis tectonics assumed to have produced Noctis. If the lower calculated antipodal pressures for Argyre were capable of producing disrupted terrains, then the terrains have been covered subsequently by volcanic or aeolian material, or modified beyond recognition.

  14. Materials and Fuels Complex Hazardous Waste Management Act/Resource Conservation and Recovery Act Storage and Treatment Permit Reapplication, Environmental Protection Agency Number ID4890008952

    SciTech Connect

    Holzemer, Michael J.; Hart, Edward

    2015-04-01

    Hazardous Waste Management Act/Resource Conservation and Recovery Act Storage and Treatment Permit Reapplication for the Idaho National Laboratory Materials and Fuels Complex Hazardous Waste Management Act/Resource Conservation and Recovery Act Partial Permit, PER-116. This Permit Reapplication is required by the PER-116 Permit Conditions I.G. and I.H., and must be submitted to the Idaho Department of Environmental Quality in accordance with IDAPA 58.01.05.012 [40 CFR §§ 270.10 and 270.13 through 270.29].

  15. Geomorphological characteristics of Yedoma terrains in the northern part of Seward Peninsula, Alaska

    NASA Astrophysics Data System (ADS)

    Stephani, E.; Dillon, M.; Fortier, D.; Jorgenson, T.; Kanevskiy, M. Z.; Shur, Y.

    2009-12-01

    Yedoma (Ice Complex) is a Late Pleistocene periglacial formation of syngenetic permafrost with large ice wedges. These extremely ice-rich stratigraphic sequences have been widely observed and studied in northern Siberia. However, very few studies have focused on Yedoma terrain in Northern America. Occurrence of Yedoma landscape has a great significance for paleoenvironmental reconstructions because the regions where Yedoma can be observed remained unglaciated during the late Pleistocene. Understanding the dynamics of Yedoma landscape and the geotechnical properties of this permafrost unit is necessary for modeling the evolution of the periglacial landscape in the context of climate change. Degradation of Yedoma terrain triggers several geomorphological processes such as thaw settlement due to deepening of the active layer, development of thermokarst lakes, thermo-erosion gullies, and active layer detachment slides. Degradation of yedoma terrain also releases greenhouse gases (e.g. methane, CO2), water from melting ice, and various types of mineral and organic sediments which need to be accounted for in climate warming scenarios. Yedoma terrains in their contemporary state can be identified by the presence of typical geomorphological features such as erosional remnants with specific shape, baidjarakhs (ground mounds formed as a result of wedge-ice thawing), abundance of thermokarst lakes, drained lakes basins, low-gradient streams and erosion-thermokarst valleys (alas valleys) with occasional pingos. We have studied and characterized in the field the metrics of two Yedoma sites at the northern part of Seward Peninsula. Geomorphic sub-units such as drained lake basins and Yedoma remnants have been characterized in detail via optical leveling surveys. Bathymetry of thermokarst lakes was measured by lake-based sonar and GPS surveys. Drilling was conducted in several locations along the survey transects. The cores retrieved were described in the field in terms of

  16. Terrain-Corrected Gamma: Improved Thematic Land-Cover Retrieval for SAR with Robust Radiometric Terrain Correction

    NASA Astrophysics Data System (ADS)

    Small, David; Miranda, Nuno; Zuberbuhler, Lukas; Schubert, Adrian; Meier, Erich

    2010-12-01

    In regions with significant terrain variations, the modulation of SAR backscatter by mountain slopes can dominate interpretation of the radar imagery unless effective countermeasures are first applied. We first demonstrate deficiencies in conventional radiometric treatments. Geocoded-terrain-corrected (GTC) products assume an ellipsoid-model for the radiometry, even if they improve upon geocoded-ellipsoid-corrected (GEC) imagery by properly compensating for the effects of terrain variations on image geometry. Both the sigma nought and gamma nought radiometric normalisation conventions as applied to distributed targets have an ellipsoidal Earth assumption at their core. Simply using a local-incidence-angle-mask (LIM) to normalise image radiometry fails to adequately model the image formation process. We prefer to use instead a product that we refer to as terrain-corrected gamma for backscatter analysis. The product makes use of SAR image simulation, incorporating shadow checks and proper accounting of local illuminated area in foreshortened and even layover areas: the result is a substantially improved sensor model in comparison to LIM-based backscatter retrieval. Use of terrain- corrected gamma in a radiometrically terrain-corrected (RTC) product enables multi-track and even multi- sensor image overlays, as terrain-induced backscatter variations are normalised using the available DEM. By properly normalising the hills and mountains, the growing availability of SAR images from diverse sensors can be compared on a Ò level playing fieldÓ . Time series analysis of hundreds of multi-track ASAR wide swath images covering Switzerland is shown to benefit when comparisons are made using terrain-corrected gamma rather than GTC or LIM- normalised SAR backscatter retrievals. We show how the spring snow melt period can be followed well using multi-track ASAR WS data only if terrain-corrected gamma backscatter values are used as the basis for comparison. Finally, we recommend

  17. Terrain Classification From Body-Mounted Cameras During Human Locomotion.

    PubMed

    Anantrasirichai, Nantheera; Burn, Jeremy; Bull, David

    2015-10-01

    This paper presents a novel algorithm for terrain type classification based on monocular video captured from the viewpoint of human locomotion. A texture-based algorithm is developed to classify the path ahead into multiple groups that can be used to support terrain classification. Gait is taken into account in two ways. Firstly, for key frame selection, when regions with homogeneous texture characteristics are updated, the frequency variations of the textured surface are analyzed and used to adaptively define filter coefficients. Secondly, it is incorporated in the parameter estimation process where probabilities of path consistency are employed to improve terrain-type estimation. When tested with multiple classes that directly affect mobility-a hard surface, a soft surface, and an unwalkable area-our proposed method outperforms existing methods by up to 16%, and also provides improved robustness.

  18. Dry air-surface exchange in hilly terrain

    SciTech Connect

    Gao, W.; Wesely, M.L.; Cook, D.R.; Hart, R.L.

    1991-01-01

    Surface fluxes of sensible heat, water vapor, carbon dioxide, ozone, and momentum were measured by using the eddy correlation method near the top of a small hill within the Konza Prairie in Kansas during the four 1987 Intensive Field Campaigns of the First ISLSCP Field Experiment (FIFE). Parameterizations of dry air-surface exchange in nonuniform terrain were examined. Larger drag coefficients, larger surface roughness lengths, and smaller aerodynamic resistances appeared to be associated with the deeper, rolling terrain upwind. Surface resistances were less affected by terrain inhomogeneities but were closely related to levels of photosynthetically active radiation. Normalized standard deviations of temperature, humidity, and vertical velocity are slightly different from values predicted by similarity relationships for uniform surfaces. The influences of these differences on fluxes estimated by use of a variance technique are relatively small as compared to the data scatter; computed variance fluxes are statistically in good agreement with eddy correlation fluxes. 11 refs., 7 figs.

  19. A reactive system for open terrain navigation: Performance and limitations

    NASA Technical Reports Server (NTRS)

    Langer, D.; Rosenblatt, J.; Hebert, M.

    1994-01-01

    We describe a core system for autonomous navigation in outdoor natural terrain. The system consists of three parts: a perception module which processes range images to identify untraversable regions of the terrain, a local map management module which maintains a representation of the environment in the vicinity of the vehicle, and a planning module which issues commands to the vehicle controller. Our approach is to use the concept of 'early traversability evaluation', and on the use of reactive planning for generating commands to drive the vehicle. We argue that our approach leads to a robust and efficient navigation system. We illustrate our approach by an experiment in which a vehicle travelled autonomously for one kilometer through unmapped cross-country terrain.

  20. Use of X-band weather radar to support the terrain database integrity monitoring and terrain referenced navigation function

    NASA Astrophysics Data System (ADS)

    Singh, Abhijeet; Uijt de Haag, Maarten

    2007-04-01

    To enable safe use of Synthetic Vision Systems (SVS) at lower altitudes, real-time sensor measurements are required to ensure the integrity of terrain and obstacle models stored in the onboard SVS and to detect hazards that may have been omitted from the stored models. This paper discusses various aspects of using X-band weather radar for terrain database integrity monitoring and terrain referenced navigation. Feature extraction methods will be addressed to support the correlation process between the weather radar measurements and the stored terrain databases. Furthermore, improved weather radar antenna models will be discussed to more reliably perform the shadow detection and extraction (SHADE) functionality. In support of the navigation function, methods will be introduced to estimate aircraft state information, such as velocity, from the geometrical changes in the observed terrain imagery. The outputs of these methods will be compared to the state estimates derived from Global Positioning System (GPS) and Inertial Navigation System (INS) measurements. All methods discussed in this paper will be evaluated using flight test data collected with a Gulfstream V in Reno, NV.

  1. Irregular Morphing for Real-Time Rendering of Large Terrain

    NASA Astrophysics Data System (ADS)

    Kalem, Sid'Ali; Kourgli, Assia

    2016-06-01

    The following paper proposes an alternative approach to the real-time adaptive triangulation problem. A new region-based multi-resolution approach for terrain rendering is described which improves on-the-fly the distribution of the density of triangles inside the tile after selecting appropriate Level-Of-Detail by an adaptive sampling. This proposed approach organizes the heightmap into a QuadTree of tiles that are processed independently. This technique combines the benefits of both Triangular Irregular Network approach and region-based multi-resolution approach by improving the distribution of the density of triangles inside the tile. Our technique morphs the initial regular grid of the tile to deformed grid in order to minimize approximation error. The proposed technique strives to combine large tile size and real-time processing while guaranteeing an upper bound on the screen space error. Thus, this approach adapts terrain rendering process to local surface characteristics and enables on-the-fly handling of large amount of terrain data. Morphing is based-on the multi-resolution wavelet analysis. The use of the D2WT multi-resolution analysis of the terrain height-map speeds up processing and permits to satisfy an interactive terrain rendering. Tests and experiments demonstrate that Haar B-Spline wavelet, well known for its properties of localization and its compact support, is suitable for fast and accurate redistribution. Such technique could be exploited in client-server architecture for supporting interactive high-quality remote visualization of very large terrain.

  2. Digital terrain modelling and industrial surface metrology - Converging crafts

    USGS Publications Warehouse

    Pike, R.J.

    2001-01-01

    Quantitative characterisation of surface form, increasingly from digital 3-D height data, is cross-disciplinary and can be applied at any scale. Thus, separation of industrial-surface metrology from its Earth-science counterpart, (digital) terrain modelling, is artificial. Their growing convergence presents an opportunity to develop in surface morphometry a unified approach to surface representation. This paper introduces terrain modelling and compares it with metrology, noting their differences and similarities. Examples of potential redundancy among parameters illustrate one of the many issues common to both disciplines. ?? 2001 Elsevier Science Ltd. All rights reserved.

  3. Applications of Microwaves to Remote Sensing of Terrain

    NASA Technical Reports Server (NTRS)

    Porter, R. A.

    1975-01-01

    A survey and study was conducted to define the role that microwaves may play in the measurement of a variety of terrain-related parameters. The survey consisted of discussions with many users and researchers in the field of remote sensing. In addition, a survey questionnaire was prepared and replies were solicited from these and other users and researchers. The results of the survey, and associated bibliography, were studied and conclusions were drawn as to the usefulness of radiometric systems for remote sensing of terrain.

  4. Terrain Modelling for Immersive Visualization for the Mars Exploration Rovers

    NASA Technical Reports Server (NTRS)

    Wright, J.; Hartman, F.; Cooper, B.; Maxwell, S.; Yen, J.; Morrison, J.

    2004-01-01

    Immersive environments are being used to support mission operations at the Jet Propulsion Laboratory. This technology contributed to the Mars Pathfinder Mission in planning sorties for the Sojourner rover and is being used for the Mars Exploration Rover (MER) missions. The stereo imagery captured by the rovers is used to create 3D terrain models, which can be viewed from any angle, to provide a powerful and information rich immersive visualization experience. These technologies contributed heavily to both the mission success and the phenomenal level of public outreach achieved by Mars Pathfinder and MER. This paper will review the utilization of terrain modelling for immersive environments in support of MER.

  5. A Novel Kinematic Model for Rough Terrain Robots

    NASA Astrophysics Data System (ADS)

    Auchter, Joseph; Moore, Carl A.; Ghosal, Ashitava

    We describe in detail a novel kinematic simulation of a three—wheeled mo bile robot moving on extremely uneven terrain. The purpose of this simulation is to test a new concept, called Passive Variable Camber (PVC), for reducing undesir able wheel slip. PVC adds an extra degree of freedom at each wheel/platform joint, thereby allowing the wheel to tilt laterally. This extra motion allows the vehicle to better adapt to uneven terrain and reduces wheel slip, which is harmful to vehicle efficiency and performance.

  6. Robotic concepts for operation in barren terrain. Final report

    SciTech Connect

    Dowling, K.

    1993-01-01

    We have performed a series of studies and configurations for robots that are capable of operating in rough barren terrains. The environments we are targeting are like those of the moon or other planets in the roughness and starkness of the terrains, the loose and hard materials that range from sandy slopes to boulder fields, and the extremes of temperature that are encountered in such places. We present a mission scenario, requirements and then present and evaluate a mechanism design. Additional subsystem issues of power, communication, sensing, and computing are all addressed with respect to these requirements.

  7. An advanced terrain modeler for an autonomous planetary rover

    NASA Technical Reports Server (NTRS)

    Hunter, E. L.

    1980-01-01

    A roving vehicle capable of autonomously exploring the surface of an alien world is under development and an advanced terrain modeler to characterize the possible paths of the rover as hazardous or safe is presented. This advanced terrain modeler has several improvements over the Troiani modeler that include: a crosspath analysis, better determination of hazards on slopes, and methods for dealing with missing returns at the extremities of the sensor field. The results from a package of programs to simulate the roving vehicle are then examined and compared to results from the Troiani modeler.

  8. Landsat analysis of tropical forest succession employing a terrain model

    NASA Technical Reports Server (NTRS)

    Barringer, T. H.; Robinson, V. B.; Coiner, J. C.; Bruce, R. C.

    1980-01-01

    Landsat multispectral scanner (MSS) data have yielded a dual classification of rain forest and shadow in an analysis of a semi-deciduous forest on Mindonoro Island, Philippines. Both a spatial terrain model, using a fifth side polynomial trend surface analysis for quantitatively estimating the general spatial variation in the data set, and a spectral terrain model, based on the MSS data, have been set up. A discriminant analysis, using both sets of data, has suggested that shadowing effects may be due primarily to local variations in the spectral regions and can therefore be compensated for through the decomposition of the spatial variation in both elevation and MSS data.

  9. A vehicle-terrain system modeling and simulation approach to mobility analysis of vehicles on soft terrain

    NASA Astrophysics Data System (ADS)

    Pan, Weidong; Papelis, Yiannis E.; He, Yefei

    2004-09-01

    This paper presents an approach to modeling and simulation of vehicles interacting with the environment (terrain) in a realistic, three-dimensional setting and to assess vehicle mobility based on simulation results. To reliably predict vehicle performance under realistic off-road conditions, lumped-parameter models commonly used in vehicle dynamics are not adequate. In this work, high fidelity, multibody dynamics approach is employed to capture vehicle nonlinear dynamic characteristics. Because all vehicle control forces/moments are generated at the patch where tire and terrain interacts, tire modeling, soil modeling, and tire-soil interaction modeling are critical. In this work, tire is modeled as multiple-input-multiple-output system with parameters determined via high-fidelity physical-based finite element model and/or test data; soil is modeled using the Bekker-Wong approach with parameters determined using high-fidelity physical-based finite element soil model and/or test data. Although the Bekker-Wong approach is relatively old, effective implementation to achieve its fully potential is possible only recently, with the advent of the so-called dynamic terrain database. A computational algorithm for such an implementation is presented. Dynamic terrain allows natural treatment of the multiple-pass problem in spatial and dynamic fashion, as opposed to the approaches found in the literature that can only deal with planar, steady-state rolling in an ad hoc fashion. Tire-terrain interaction is modeled using a hybrid approach of empirical and semi-empirical models. A complete simulation environment can be constructed by integrating all the models and mobility analysis of vehicles be perform on soft terrain. An example is presented to demonstrate the approach. Conclusions and future research directions are presented at the end of the paper.

  10. Adapting Tilt Corrections and the Governing Flow Equations for Steep, Fully Three-Dimensional, Mountainous Terrain

    NASA Astrophysics Data System (ADS)

    Oldroyd, Holly J.; Pardyjak, Eric R.; Huwald, Hendrik; Parlange, Marc B.

    2016-06-01

    In recent studies of atmospheric turbulent surface exchange in complex terrain, questions arise concerning velocity-sensor tilt corrections and the governing flow equations for coordinate systems aligned with steep slopes. The standard planar-fit method, a popular tilt-correction technique, must be modified when applied to complex mountainous terrain. The ramifications of these adaptations have not previously been fully explored. Here, we carefully evaluate the impacts of the selection of sector size (the range of flow angles admitted for analysis) and planar-fit averaging time. We offer a methodology for determining an optimized sector-wise planar fit (SPF), and evaluate the sensitivity of momentum fluxes to varying these SPF input parameters. Additionally, we clarify discrepancies in the governing flow equations for slope-aligned coordinate systems that arise in the buoyancy terms due to the gravitational vector no longer acting along a coordinate axis. New adaptions to the momentum equations and turbulence kinetic energy budget equation allow for the proper treatment of the buoyancy terms for purely upslope or downslope flows, and for slope flows having a cross-slope component. Field data show that new terms in the slope-aligned forms of the governing flow equations can be significant and should not be omitted. Since the optimized SPF and the proper alignment of buoyancy terms in the governing flow equations both affect turbulent fluxes, these results hold implications for similarity theory or budget analyses for which accurate flux estimates are important.

  11. Sink detection on tilted terrain for automated identification of glacial cirques

    NASA Astrophysics Data System (ADS)

    Prasicek, Günther; Robl, Jörg; Lang, Andreas

    2016-04-01

    Glacial cirques are morphologically distinct but complex landforms and represent a vital part of high mountain topography. Their distribution, elevation and relief are expected to hold information on (1) the extent of glacial occupation, (2) the mechanism of glacial cirque erosion, and (3) how glacial in concert with periglacial processes can limit peak altitude and mountain range height. While easily detectably for the expert's eye both in nature and on various representations of topography, their complicated nature makes them a nemesis for computer algorithms. Consequently, manual mapping of glacial cirques is commonplace in many mountain landscapes worldwide, but consistent datasets of cirque distribution and objectively mapped cirques and their morphometrical attributes are lacking. Among the biggest problems for algorithm development are the complexity in shape and the great variability of cirque size. For example, glacial cirques can be rather circular or longitudinal in extent, exist as individual and composite landforms, show prominent topographic depressions or can entirely be filled with water or sediment. For these reasons, attributes like circularity, size, drainage area and topology of landform elements (e.g. a flat floor surrounded by steep walls) have only a limited potential for automated cirque detection. Here we present a novel, geomorphometric method for automated identification of glacial cirques on digital elevation models that exploits their genetic bowl-like shape. First, we differentiate between glacial and fluvial terrain employing an algorithm based on a moving window approach and multi-scale curvature, which is also capable of fitting the analysis window to valley width. We then fit a plane to the valley stretch clipped by the analysis window and rotate the terrain around the center cell until the plane is level. Doing so, we produce sinks of considerable size if the clipped terrain represents a cirque, while no or only very small sinks

  12. New formulation for interferometric synthetic aperture radar for terrain mapping

    SciTech Connect

    Jakowatz, C.V. Jr.; Wahl, D.E.; Eichel, P.H.; Thompson, P.A.

    1994-04-01

    The subject of interferometric synthetic aperture radar (IFSAR) for high-accuracy terrain elevation mapping continues to gain importance in the arena of radar signal processing. Applications to problems in precision terrain-aided guidance and automatic target recognition, as well as a variety of civil applications, are being studied by a number of researchers. Not unlike many other areas of SAR processing, the subject of IFSAR can at first glance appear to be somewhat mysterious. In this paper we show how the mathematics of IFSAR for terrain elevation mapping using a pair of spotlight mode SAR collections can be derived in a very straightforward manner. Here, we employ an approach that relies entirely on three-dimensional Fourier transforms, and utilizes no reference to range equations or Doppler concepts. The result is a simplified explanation of the fundamentals of interferometry, including an easily-seen link between image domain phase difference and terrain elevation height. The derivation builds upon previous work by the authors in which a framework for spotlight mode SAR image formation based on an analogy to three-dimensional computerized axial tomography (CAT) was developed. After outlining the major steps in the mathematics, we show how a computer simulator which utilizes three-dimensional Fourier transforms can be constructed that demonstrates all of the major aspects of IFSAR from spotlight mode collections.

  13. Shape-assisted body reorientation enhances trafficability through cluttered terrain

    NASA Astrophysics Data System (ADS)

    Li, Chen; Pullin, Andrew; Haldane, Duncan; Fearing, Ronald; Full, Robert

    2014-11-01

    Many birds and fishes have slender, streamlined bodies that reduce fluid dynamic drag and allow fast and efficient locomotion. Similarly, numerous terrestrial animals run through cluttered terrain where 3-D, multi-component obstacles like grass, bushes, trees, walls, doors, and pillars also resist motion, but it is unknown whether their body shape plays a major role. Here, we challenged discoid cockroaches that possess a rounded, thin, nearly ellipsoidal body to run through tall, narrowly spaced, grass-like beams. The animals primarily rolled their body to the side to maneuver through the obstacle gaps. Reduction of body roundness by artificial shells inhibited this side roll maneuver, resulting in a lower traversal probability and a longer traversal time (P < 0.001, ANOVA). Inspired by this discovery, we added a cockroach-like, rounded exoskeleton shell to a legged robot of a nearly cuboidal body. The rounded shell enabled the robot to use passive side rolling to maneuver through beams. To explain the mechanism, we developed a simple physics model to construct an energy landscape of the body-terrain interaction, which allowed estimation of body forces and torques exerted by the beams. Our model revealed that, by passive interaction with the terrain, a rounded body (ellipsoid) rolled more easily than an angular body (cuboid) to access energy valleys between energy barriers caused by obstacles. Our study is the first to demonstrate that a terradynamically ``streamlined'' shape can reduce terrain resistance and enhance trafficability by assisting body reorientation.

  14. Distant Secondary Craters and Age Constraints on Young Martian Terrains

    NASA Technical Reports Server (NTRS)

    McEwen, A.; Preblich, B.; Turtle, E.; Studer, D.; Artemieva, N.; Golombek, M.; Hurst, M.; Kirk, R.; Burr, D.

    2005-01-01

    Are small (less than approx. 1 km diameter) craters on Mars and the Moon dominated by primary impacts, by secondary impacts of much larger primary craters, or are both primaries and secondaries significant? This question is critical to age constraints for young terrains and for older terrains covering small areas, where only small craters are superimposed on the unit. If the martian rayed crater Zunil is representative of large impact events on Mars, then the density of secondaries should exceed the density of primaries at diameters a factor of 1000 smaller than that of the largest contributing primary crater. On the basis of morphology and depth/diameter measurements, most small craters on Mars could be secondaries. Two additional observations (discussed below) suggest that the production functions of Hartmann and Neukum predict too many primary craters smaller than a few hundred meters in diameter. Fewer small, high-velocity impacts may explain why there appears to be little impact regolith over Amazonian terrains. Martian terrains dated by small craters could be older than reported in recent publications.

  15. The thumbprint terrain: What will Mars Observer tell us?

    NASA Technical Reports Server (NTRS)

    Schaefer, M. W.

    1993-01-01

    Some of the more puzzling features seen on Mars are those known as curvilinear features or 'thumb print' terrain, types of patterned ground found in the northern plains. The thumbprint terrain, named for its resemblance to the lines of a human thumbprint is found on what appears to be level, relatively low-lying ground near the crustal dichotomy boundary. It is often found near the termini of large channels. There are three types of thumbprint terrain in the classification of Rossbacher and Judson. The first consists of ridges and depressions about a kilometer wide, separated by a few kilometers, and with an apparent relief of 40-100 m. The second consists of steep-sided, flat-floored depressions about a kilometer wide, separated by a few kilometers, and with an apparent relief of 10-290 m. The third consists only of albedo markings, with a typical scale of about a kilometer. Many models were proposed to explain the origin of this terrain. It was suggested that it was caused by lava flows, removal of debris mantles, glaciers, or karst. However, the most popular models at present involve the action of subsurface ice to form such thermokarst features as striped ground, solifluction lobes, and/or linear, ice-cored ridges. There are several instruments on the Mars Observer spacecraft that will be able to provide us with information useful in distinguishing between these models.

  16. Group Dynamics and Decision Making: Backcountry Recreationists in Avalanche Terrain

    ERIC Educational Resources Information Center

    Bright, Leslie Shay

    2010-01-01

    The purpose of this study was to describe and determine the prevalence of decision-making characteristics of recreational backcountry groups when making a decision of where to travel and ride in avalanche terrain from the perspective of individuals. Decision-making characteristics encompassed communication, decision-making processes, leadership,…

  17. Comparing seismic susceptibility models of the Himalayan terrain

    NASA Astrophysics Data System (ADS)

    Som, S. K.; Dasarwar, P.; Mohan, Murali; Hindayar, J. N.; Kumar, N. Thrideep; Chowdhuri, S. N.; Darmwal, G. S.; Singh, Harbans

    2016-07-01

    The ongoing intra-continental collision between the Indian and Eurasian plates along the Himalayas has resulted in many damaging earthquakes with severe damages to man-made structures and natural landscapes due to ground shaking and ground failure, which in turn depends on geomorphological, geological and geophysical variables. Seismic susceptibility models are developed for Gangtok City by combining all the three variables using both knowledge-driven and data-driven methods on facet and grid cell terrain units. Finally, the results are critically evaluated by validation with the earthquake intensity data recorded during earthquake events. First-stage modelling attempt using different knowledge-driven methods on different terrain units shows bi-modal data distribution with low predictability due to extremely rugged topography with wide altitudinal variations within short distances. Second-stage modelling of separated population by using the same methodologies increases model predictability in which one model method describes the higher topographic levels better and the other model method is found to be better for lower topographic levels. Seismic susceptibility of the area is best described by composite models, combining different best methods of fine classification for lower and higher topographic levels having the same mapping/terrain units. Comparison of the composite models shows that the terrain unit does not play a significant role but the type of models selected determines the best possible seismic susceptibility map of the area.

  18. VIEW OF REAR YARDS AND TERRAIN, SHOWING FACILITIES 571 AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF REAR YARDS AND TERRAIN, SHOWING FACILITIES 571 AND 507. CONDOMINIUM TOWERS CAN BE SEEN IN THE DISTANCE. VIEW FACING WEST - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, Intersection of Acacia Road and Brich Circle, Pearl City, Honolulu County, HI

  19. A structural origin for the cantaloupe terrain of Triton

    NASA Technical Reports Server (NTRS)

    Boyce, Joseph M.

    1993-01-01

    Cantaloupe terrain is unique to Triton. It is Triton's oldest terrain and includes about 250,000 km sq. region displaying sparsely cratered, closely spaced, nearly circular dimples about 30-40 km across. This terrain is found on no other planet because, only on Triton the final major global thermal pulse (1) caused completed (or nearly) interior melting resulting in a cooling history where large thermal stresses shattered and contorted a thin, weak lithosphere, and (2) occurred after heavy bombardment so that the surface features were preserved. The cantaloupe terrain is composed of intersecting sets of structures (folds and/or faults) that have developed as a result of global compression generated by volumetric changes associated with cooling of Triton's interior. Further, it is proposed that these structures developed after the period of heavy bombardment, and resulted from the last major global thermal epoch in Triton's unique history (either caused by tidal or radio metric heating). Initially, as the body cooled and the structures formed, their surface topography was most likely modified by thermal relaxation of the warm surface ices. In other bodies like Mercury, thermal stresses generated from global cooling and contraction have resulted in widely spaced thrust faults, whereas on Triton, thermal stresses produced more closely-spaced folds and faults sets. This difference in structural style is probably due to differences in lithospheric properties (thickness, strength, etc.), the magnitude of stress (directly dependent on the thermal history), and when the structures formed, relative to the period of heavy bombardment.

  20. AirMSPI PODEX LaJolla Terrain Images

    Atmospheric Science Data Center

    2013-12-13

    ... Images from the PODEX 2013 Campaign   La Jolla target (La Jolla, California) 01/14/2013 Terrain-projected   ... central observation tttt:                 Target name aaa:               Mean viewing angle (reported to the ...