Science.gov

Sample records for agency complex terrain

  1. EPA (ENVIRONMENTAL PROTECTION AGENCY) COMPLEX TERRAIN MODEL DEVELOPMENT: THIRD MILESTONE REPORT 1983

    EPA Science Inventory

    The U.S. Environmental Protection Agency is sponsoring the Complex Terrain Model Development program, a multi-year integrated program to develop and validate practical plume dispersion models of known reliability and accuracy for simulating one-hour-average ground-level concentra...

  2. EPA (ENVIRONMENTAL PROTECTION AGENCY) COMPLEX TERRAIN MODEL DEVELOPMENT. FOURTH MILESTONE REPORT - 1984

    EPA Science Inventory

    The U.S. Environmental Protection Agency is sponsoring the Complex Terrain Development program, a multi-year integrated program to develop, and validate practical plume dispersion models of known reliability and accuracy for simulating one-hour-average ground-level concentrations...

  3. EPA (ENVIRONMENTAL PROTECTION AGENCY) COMPLEX TERRAIN MODEL: THEORETICAL BASIS AND PRELIMINARY EVALUATION

    EPA Science Inventory

    The theoretical basis, physical structure, and preliminary evaluation of the U.S. Environmental Protection Agency's Complex Terrain Dispersion Model (CTDM) are described. CTDM is a point-source plume model designed primarily to estimate windward-side surface concentrations on dis...

  4. EPA (ENVIRONMENTAL PROTECTION AGENCY) COMPLEX TERRAIN MODEL DEVELOPMENT DESCRIPTION OF A COMPUTER DATA BASE FROM SMALL HILL IMPACTION STUDY NO. 1, CINDER CONE BUTTE, IDAHO

    EPA Science Inventory

    As part of the U.S. Environmental Protection Agency's effort to develop and demonstrate a reliable model of atmospheric dispersion for pollutant emissions in irregular mountainous terrain, the Complex Terrain Model Development Program was initiated. The first phase, a comprehensi...

  5. SUMMARY OF COMPLEX TERRAIN MODEL EVALUATION

    EPA Science Inventory

    The Environmental Protection Agency conducted a scientific review of a set of eight complex terrain dispersion models. TRC Environmental Consultants, Inc. calculated and tabulated a uniform set of performance statistics for the models using the Cinder Cone Butte and Westvaco Luke...

  6. Atmospheric processes over complex terrain

    NASA Astrophysics Data System (ADS)

    Banta, Robert M.; Berri, G.; Blumen, William; Carruthers, David J.; Dalu, G. A.; Durran, Dale R.; Egger, Joseph; Garratt, J. R.; Hanna, Steven R.; Hunt, J. C. R.

    1990-06-01

    A workshop on atmospheric processes over complex terrain, sponsored by the American Meteorological Society, was convened in Park City, Utah from 24 vto 28 October 1988. The overall objective of the workshop was one of interaction and synthesis--interaction among atmospheric scientists carrying out research on a variety of orographic flow problems, and a synthesis of their results and points of view into an assessment of the current status of topical research problems. The final day of the workshop was devoted to an open discussion on the research directions that could be anticipated in the next decade because of new and planned instrumentation and observational networks, the recent emphasis on development of mesoscale numerical models, and continual theoretical investigations of thermally forced flows, orographic waves, and stratified turbulence. This monograph represents an outgrowth of the Park City Workshop. The authors have contributed chapters based on their lecture material. Workshop discussions indicated interest in both the remote sensing and predictability of orographic flows. These chapters were solicited following the workshop in order to provide a more balanced view of current progress and future directions in research on atmospheric processes over complex terrain.

  7. EPA (ENVIRONMENTAL PROTECTION AGENCY) COMPLEX TERRAIN MODEL DEVELOPMENT: DESCRIPTION OF A COMPUTER DATA BASE FROM THE FULL SCALE PLUME STUDY, TRACY POWER PLANT, NEVADA

    EPA Science Inventory

    As part of the EPA's Complex Terrain Model Development Program, the Full Scale Study was conducted at the Tracy Power Plant near Reno, Nevada. SO6 tracer gas and oil-fog particles were injected into the base of a 91.4 smokestack, and CF3Br tracer was released from one of three le...

  8. EPA (ENVIRONMENTAL PROTECTION AGENCY) COMPLEX TERRAIN MODEL DEVELOPMENT: DESCRIPTION OF A COMPUTER DATA BASE FROM SMALL HILL IMPACTION STUDY NO. 2, HOGBACK RIDGE, NEW MEXICO

    EPA Science Inventory

    The second field study of EPA's Complex Terrain Model Development Program, Small Hill Impaction Study No. 2, was conducted along a 1.5-km section of the Hogback Ridge near Farmington, New Mexico in October 1982. Eleven quantative tracer experiments were performed, each lasting 8 ...

  9. EPA (ENVIRONMENTAL PROTECTION AGENCY) MODEL DEVELOPMENT FOR STABLE PLUME IMPINGEMENT ON ELEVATED TERRAIN OBSTACLES

    EPA Science Inventory

    The U.S. Environmental Protection Agency's Complex Terrain Model Development program is designed as a series of progressively advanced model development efforts accompanied by requisite field studies to provide data for model evaluation. Plume impingement studies have been perfor...

  10. 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.

  11. Neutral surface layer turbulence over complex terrain

    SciTech Connect

    Bowen, B.M.

    1995-09-01

    Accurate turbulence estimates are important input to atmospheric dispersion models since they characterize downwind dispersion and hence, potential pollutant concentrations. When only basic wind information is available, an atmospheric modeler must first estimate roughness length (z{sub 0},) at the location of interest, ({mu}*) from similarity theory using average wind speed ({mu}) and z{sub 0}, and finally apply experimentally derived relationships to determine the turbulence intensities. Even when turbulence coefficients are measured, the turbulence profile must be estimated in the surface layer, using, for example, the power law recommended in a US Environmental Protection Agency guidance document. In this study, turbulent intensities and wind profiles are analyzed in eight direction sectors during near neutral stability. ``Local`` and ``regional`` roughness lengths are calculated from wind speed profiles and from longitudinal turbulence intensities ({sigma}{sub {mu}}) at both sites. With ``regional`` roughness length, complex terrain features are in effect the roughness elements. Profiles of median, 15-minute averaged turbulence intensities {sigma}{sub {mu}}, {sigma}{sub {nu}} and {sigma}{sub w} are calculated at both sites. Profiles of median {sigma}{sub {theta}} and {sigma}{sub {phi}} are also calculated using four mean values of regional z{sub 0} at both sites. Finally, differences between widely-used turbulence relationships and the relationships determined in this study, and their possible effect on model results, are discussed.

  12. 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.

  13. 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.

  14. 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.

  15. Assessing the complexity of topographic mass in complex terrains

    NASA Astrophysics Data System (ADS)

    Kurmankozhayev, Azimkhan; Nemec, Vaclav; Sarybaev, Edil

    2014-05-01

    To assess the structure of terrain more objectively it is necessary to supplement and clarify the available characteristics with a number of numerical statistical indicators and formulas that reflect the actual links between separate features of terrain. Results from analysis of traditional variability assessment methods for characteristics of georesources allow concluding that a characteristic's variability usually has oscillatory and wavelike geometric image in the form of broken, polygonal, zigzagging, polyhedral and, less frequently, regular geometric shapes, defined by deviation amplitude and period of irregularities. It is established that variability cannot be evaluated with one universal indicator since variability consists of a random and a regular component, thus it is considered reasonable to assess the characteristic's variability depending on current mining and geometrical tasks and by stages of georesources development. The recommended topographic terrain mass complexity assessment method is based on the leading concept of using properties of specific anti-entropy that, unlike regular entropy, allows accounting for changes in total number of component elements in stable populations for the topographic terrain mass. Concept of utilizing value of specific anti-entropy, widely used in information theory, is taken as an assessment criterion for integral complexity of topographic terrain mass. Modification of specific anti-entropy formula, as applied to substance of formation of the georesource development target's topographic mass integral complexity, is based on qualimetric model of its assessment. Essence of the model comes down to determining the topographic mass complexity using the topographic mass structure uncertainty measure, assessed using the quantity of heterogeneous morphometric elements contained in the topographic surface of terrain. The main basic reference value in qualimetric model of the topographic terrain mass complexity is the

  16. Predicting Potential Evaporation in Topographically Complex Terrain

    NASA Astrophysics Data System (ADS)

    Koohafkan, M.; Thompson, S. E.; Hamilton, M. P.

    2012-12-01

    Predicting and understanding the water cycle in topographically complex terrain poses challenges for upscaling point-scale measurements of water and energy balance and for downscaling observations made from remote sensing or predictions made via global circulation models. This study evaluates hydrologic and climate data drawn from a spatially-distributed wireless sensor network at the Blue Oak Ranch Reserve near San Jose, California to investigate the influence of topographic variation, landscape position, and local ecology (vegetation) on one core component of the water balance: potential evaporation. High-resolution observations of solar radiation, ambient temperature, wind speed, and relative humidity are combined with canopy maps generated from LiDAR flyovers to develop spatially-distributed predictions of potential evaporation. These data are compared to estimates of EP based on inverse modeling of surface soil moisture data. Preliminary results suggest that the spatial structure of microclimate at Blue Oak Ranch Reserve is dominated by variations around the elevation gradient, with strong nocturnal inversions hypothesized to reflect the influence of the coastal marine layer. Estimates of EP based on the Penman-Monteith equation suggest that EP could vary by up to a factor of 5 across the site, with differences in vapor pressure deficit and canopy height largely responsible for this variability. The results suggest that a) large differences in the timing and magnitude of water stress could arise in topographically complex terrain due to localized differences in energy balance, and b) both localized and regional effects need to be accounted for when downscaling climate data over topographically complex sites. 2) Color map showing preliminary estimates of annual EP incorporating canopy information (spatially-distributed values of aerodynamic resistance and LAI) drawn from LiDAR imagery. The effect of the resistance on the dynamics is striking in its ability to

  17. 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

  18. Synoptic Flow Interactions in Complex Terrain

    NASA Astrophysics Data System (ADS)

    Hocut, C. M.; Silver, Z.; Wang, Y.; Creegan, E.; Felton, M.; Hoch, S.; Fernando, H. J.; Di Sabatino, S.; Leo, L.; Dimitrova, R.; Zsedrovits, T.; Pardyjak, E.; Huynh, G.

    2014-12-01

    In the spring of 2013, the Mountain Terrain Atmospheric Modeling and Observations Program (MATERHORN) conducted its second extensive field experiment at the Granite Mountain Atmospheric Science Testbed (GMAST), US Army Dugway Proving Grounds (DPG), Utah. Of particular interest to MATERHORN-X-2 were synoptic dominated conditions in which synoptic flows interacted with thermal circulations and the topography leading to modulations of the thermal circulations and external-flow generated lee and progressive waves and if the Froude number was low; eddies, large vortices, wakes and waves developed in the lee of Granite Mountain. To capture these phenomena, a suite of advanced instrumentation was used, which could characterize the upstream unmodified synoptic approach flow and identify the synoptic flow / mountain interactions. In addition to meteorological towers, Doppler LiDARs, placed at two locations to the east and in the lee of Granite Mountain were particularly useful, showing the horizontal spatial pattern and temporal evolution of the synoptic generated phenomena. WRF simulations were used to provide analysis guidance. This research was funded by Office of Naval Research Grant # N00014-11-1-0709 and the Air Force Weather Agency.

  19. Path planning for complex terrain navigation via dynamic programming

    SciTech Connect

    Kwok, K.S.; Driessen, B.J.

    1998-12-31

    This work considers the problem of planning optimal paths for a mobile robot traversing complex terrain. In addition to the existing obstacles, locations in the terrain where the slope is too steep for the mobile robot to navigate safely without tipping over become mathematically equivalent to extra obstacles. To solve the optimal path problem, the authors use a dynamic programming approach. The dynamic programming approach utilized herein does not suffer the difficulties associated with spurious local minima that the artificial potential field approaches do. In fact, a globally optimal solution is guaranteed to be found if a feasible solution exists. The method is demonstrated on several complex examples including very complex terrains.

  20. METEOROLOGICAL EVENTS THAT PRODUCED THE HIGHEST GROUND-LEVEL CONCENTRATIONS DURING COMPLEX TERRAIN FIELD EXPERIMENTS

    EPA Science Inventory

    The U.S. Environmental Protection Agency (EPA) is sponsoring the Complex Terrain Model Development project, a multi-year study to develop improved models for calculating ground-level air pollutant concentrations that result from large emission sources located in mountainous terra...

  1. 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.

  2. 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.

  3. (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.

  4. Boundary Layer Measurements in Complex Terrain: Innsbruck-Box

    NASA Astrophysics Data System (ADS)

    Stiperski, I.; Rotach, M. W.; Gohm, A.

    2012-04-01

    Planetary boundary layers in complex terrain remain one of the major challenges of today's boundary layer research. Our current knowledge of the characteristics of the turbulence structure and exchange processes in truly complex topography remains limited. Not only is there no suitable theory, it is not known if all the relevant processes such a theory should explain are accounted for. Meanwhile, the increasing resolution of both numerical weather prediction and regional climate models demands precisely such information for improving model performance. Except for a few recent field campaigns, limited both in time and focus, no measurement platform in highly complex terrain is available to date that would be able to provide a complete dataset of boundary layer information in sufficient complexity, resolution and covering all regimes of interest both for model validation and resolving the remaining scientific questions. The Dynamic Meteorology Group of the Institute of Meteorology and Geophysics, University of Innsbruck is presently setting up such a 'reference box', which aims to fill in this gap. It will consist of a combination of high-resolution long-term turbulence observations in an area in the vicinity of Innsbruck (hence the 'Innsbruck-Box') and high-resolution numerical modeling. Whereas the data provided by measurements will allow for improvements in process understanding and model validation, the numerical modeling will be used to fill the data gaps in areas where no measurements are possible or the current measurement techniques are inadequate. Also, numerical experiments using idealized terrain or settings can be performed in order to test hypotheses deduced from the observations. The Innsbruck-Box is designed to be a long-term reference platform for studying boundary layer processes in highly complex terrain with an integrated measurement approach. Sites are located in the Inn-Valley, an approximately East-West oriented valley in western Austria

  5. Innovative Solutions for Pulsed Wind Lidar Accuracy in Complex Terrain

    NASA Astrophysics Data System (ADS)

    Boquet, M.

    2010-12-01

    Accuracy of Lidar remote sensors for wind energy has been previously reported. Coherent Doppler lidars have shown very high correlation with calibrated cup anemometers in flat terrain, both onshore and offshore. However, in more complex terrain, not only more turbulent air flow but also loss of flow homogeneity occurs, and remote sensors measurement process needs to be closely examined. We compare and simulate cup’s point and lidar’s volume measurements to understand and explain for the two sensor’s response. We emphasize the main error term in the horizontal and vertical wind speed retrieval. Geometrical optimizations of pulsed Lidar measurement process are also investigated to get more reliable wind speed estimations, such as finding the right cone angle to reduce the error. We show our conclusions and results of the CFD simulation performed on a Spanish complex terrain case. We see that there is at least one possibility to strongly reduce the relative error between Lidar and anemometer measurements. Indeed, accessing to the vertical wind speed variations leads to a considerable improvement in the linear correlation and dispersion.

  6. 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.

  7. 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.

  8. 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.

  9. Structure of the nocturnal boundary layer over a complex terrain

    SciTech Connect

    Parker, M.J.; Raman, S.

    1992-08-01

    The complex nature of the nocturnal boundary layer (NBL) has been shown extensively in the literature Project STABLE was conducted in 1988 to study NBL turbulence and diffusion over the complex terrain of the Savannah River Site (SRS) near Augusta, Georgia. The third night of the study was particularly interesting because of the unusual phenomena observed in the structure of the NBL. Further analyses of microscale and mesoscale data from this night are presented using data from SRS network of eight 61 m towers over 900 km{sup 2}, from six launches of an instrumented tethersonde, from permanent SRL meteorological instrumentation at seven levels of the 304 m (1,000 ft) WJBF-TV tower near SRS, and additional data collected at 36 m (CC) by North Carolina State University (NCSU) including a one dimensional sonic anemometer, fine wire thermocouple, and a three dimensional propeller anemometer. Also, data from the nearby Plant Vogtle nuclear power plant observation tower and the National Weather Service at Augusta`s Bush Field (AGS) are presented. The passage of a mesoscale phenomenon, defined as a microfront (with an explanation of the nomenclature used), and a vertical composite schematic of the NBL which shows dual low level wind maxima, dual inversions, and a persistent, elevated turbulent layer over a complex terrain are described.

  10. Structure of the nocturnal boundary layer over a complex terrain

    SciTech Connect

    Parker, M.J. ); Raman, S. . Dept. of Marine, Earth and Atmospheric Sciences)

    1992-01-01

    The complex nature of the nocturnal boundary layer (NBL) has been shown extensively in the literature Project STABLE was conducted in 1988 to study NBL turbulence and diffusion over the complex terrain of the Savannah River Site (SRS) near Augusta, Georgia. The third night of the study was particularly interesting because of the unusual phenomena observed in the structure of the NBL. Further analyses of microscale and mesoscale data from this night are presented using data from SRS network of eight 61 m towers over 900 km{sup 2}, from six launches of an instrumented tethersonde, from permanent SRL meteorological instrumentation at seven levels of the 304 m (1,000 ft) WJBF-TV tower near SRS, and additional data collected at 36 m (CC) by North Carolina State University (NCSU) including a one dimensional sonic anemometer, fine wire thermocouple, and a three dimensional propeller anemometer. Also, data from the nearby Plant Vogtle nuclear power plant observation tower and the National Weather Service at Augusta's Bush Field (AGS) are presented. The passage of a mesoscale phenomenon, defined as a microfront (with an explanation of the nomenclature used), and a vertical composite schematic of the NBL which shows dual low level wind maxima, dual inversions, and a persistent, elevated turbulent layer over a complex terrain are described.

  11. 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.

  12. Analysis on Turbulent Flows using Large-eddy Simulation on the Seaside Complex Terrain

    NASA Astrophysics Data System (ADS)

    Kamio, T.; Iida, M.; Arakawa, C.

    2014-12-01

    The purpose of this study is the Large-eddy Simulation (LES) of the turbulent wind on the complex terrain, and the first results of the simulation are described. The authors tried to apply the LES code, which was developed as an atmospheric simulator in Japan Agency for the Marine-Earth Science and Technology (JAMSTEC), to the wind prediction for the wind energy. On the wind simulation, the highest problem would be the boundary conditions, and the case in this paper was simplified one. The case study in this paper is the west wind on a complex terrain site, which is the wind from sea for the site. The steady flow was employed for the inlet condition, because the wind on the sea is the low turbulent wind, and almost all the turbulence would be generated by the roughness of the ground surface. The wall function was employed as the surface condition on the ground surface. The computational domain size was about 8 × 3 × 2.5 km3, and the minimum cell size was about 10 × 10 × 3 m3. The computational results, the vertical profile of the averaged wind speed and the turbulence intensity, agreed with the measurement by the meteorological masts. Moreover, the authors tried the analysis of the turbulence characteristics. The power spectrum density model, and the cross spectrum analyses gave the knowledge of the turbulent characteristics on the complex terrain and the hints for the domain and grid of the numerical analysis.

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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

  18. 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.

  19. On the interpolation of precipitation data over complex terrain

    NASA Astrophysics Data System (ADS)

    Dorninger, M.; Schneider, S.; Steinacker, R.

    2008-10-01

    The aim of this paper is to test the ability of the Vienna Enhanced Resolution Analysis Scheme (VERA) to estimate areal precipitation over complex terrain in real-time. The investigation has been performed for two severe flooding episodes in the Alpine region within three domains. The areas of the domains differ by a factor of 10 approximately. An inverse distance weighting (IDW) approach has been used to compare the VERA-fields against the results of a common interpolation scheme. Beside the routinely and in real-time available SYNOP data, the precipitation data from the dense hydrological network have been utilized on a post event basis. Efficiency and root mean square error have been used as statistical measures to characterize the quality of the results. The mean areal precipitation can be well estimated for the two cases in view from the routine available SYNOP network in the largest domain (˜170,000 km2). Additional stations from the hydrological network increase the variance in the field but do not change the mean value substantially. This finding changes for smaller domains when the mean areal precipitation increases by a factor of two by using the dense hydrological network. The two interpolation methods used show quite similar results. It seems that the nature of precipitation (large-scale versus convective) has the strongest impact on the quality of the results. For example, the efficiency drops from 0.84 (for large scale event) to about 0.47 (for convective event).

  20. 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.

  1. Three-dimensional modeling of canopy flow in complex terrain

    NASA Astrophysics Data System (ADS)

    Xu, X.; Yi, C.; Montagnani, L.

    2013-12-01

    Flows within and just above forest canopy over mountainous terrain are most complicated, which substantially influence the biosphere-atmosphere interaction of mass and energy. Due to the significant spatial variation, canopy flow in complex terrain is poorly understood based on the point-based tower measurement. We employ numerical model integrated with biogenic CO2 process to examine the impacts of topography, canopy structure, and synoptic atmospheric motion on canopy flow and associated CO2 transport in an alpine forest, with special focus on stable nocturnal condition when biogenic CO2 emission is active. Our model prediction is in better agreement with tower measurements when background synoptic wind is present, which leads to better larger-scale mixing, while local slope flow is just thermal-driven in the modeled domain by ignorance of surround mountain-valley. Our results show that large-scale synoptic wind is modified by local slope-canopy flow within and just above canopy. As the synoptic wind is down-slope (Figure 1a), recirculation is formed on the downwind slope with cool air and high accumulation of CO2 in front of tall and dense vegetation. As the synoptic wind is up-slope(Figure 1b), canopy flow at the higher elevation of the slope is in the same direction of synoptic wind, while canopy flow at the lower part of the slope blows down-slope. The upslope wind causes better mixing in the canopy and leads to smaller CO2 accumulation just close to the slope surface. The local down-slope wind (Figure 1c) causes rich and deep CO2 build-up in the downwind direction on the lower slope. Our numerical performance has demonstrated that three-dimensional CFD approach is a useful tool to understanding relationships between tower-point measurements and surrounding's field distributions. Acknowledgement: This research was supported by NSF Grants ATM-0930015, CNS-0958379 & CNS-0855217, PSC-CUNY ENHC-42-64 & CUNY HPCC. Figure 1 CO2 distribution within and just above

  2. On the Measurement of Turbulence Over Complex Mountainous Terrain

    NASA Astrophysics Data System (ADS)

    Stiperski, Ivana; Rotach, Mathias W.

    2016-04-01

    The theoretical treatment of turbulence is largely based on the assumption of horizontally homogeneous and flat underlying surfaces. Correspondingly, approaches developed over the years to measure turbulence statistics in order to test this theoretical understanding or to provide model input, are also largely based on the same assumption of horizontally homogeneous and flat terrain. Here we discuss aspects of turbulence measurements that require special attention in mountainous terrain. We especially emphasize the importance of data quality (flux corrections, data quality assessment, uncertainty estimates) and address the issues of coordinate systems and different post-processing options in mountainous terrain. The appropriate choice of post-processing methods is then tested based on local scaling arguments. We demonstrate that conclusions drawn from turbulence measurements obtained in mountainous terrain are rather sensitive to these post-processing choices and give suggestions as to those that are most appropriate.

  3. A tracer experiment study to evaluate the CALPUFF real time application in a near-field complex terrain setting

    NASA Astrophysics Data System (ADS)

    cui, Huiling; Yao, Rentai; Xu, Xiangjun; Xin, Cuntian; Yang, jinming

    2011-12-01

    CALPUFF is an atmospheric source-receptor model recommended by the US Environmental Protection Agency (EPA) for use on a case-by-case basis in complex terrain and wind condition. As the bulk of validation of CALPUFF has focused on long-range or short-range but long-term dispersion, we can not gauge the reliability of the model for predicting the short-term emission in near-field especially complex terrain, and sometimes this situation is important for emergency emission. To validate the CALPUFF's application in such condition, we carried out a tracer experiment in a near-field complex terrain setting and used CALPUFF atmospheric dispersion model to simulate the tracer experiment in real condition. From the centroid trajectory comparison of predictions and measures, we can see that the model can correctly predict the centroid trajectory and shape of tracer cloud, and the results also indicate that sufficient observed weather data only can develop a good wind field for near-field. From the concentration comparison in each arc, we can see the model underestimate horizontal extent of tracer puff and can not reflect the irregular characters showed in measurements. The result of global analysis is FOEX of -25.91%, FA2 of 27.06%, FA5 of 61.41%. The simulations shows that the CALPUFF can simulate the position and direction of tracer cloud in near-field complex terrain but underestimate over measurements especially in peak concentrations.

  4. Ecohydrological Implications of Contrasting Slope and Aspect in Complex Terrain

    NASA Astrophysics Data System (ADS)

    Seyfried, M. S.; Link, T. E.; Klos, P. Z.; Patton, N. R.; Lohse, K. A.

    2014-12-01

    Understanding how complex terrain affects ecohydrological processes is increasingly important as we attempt to understand how water and carbon fluxes are integrated across relatively large domains. Spatial variations of incoming solar radiation are well understood and quantified, but the understanding their impacts on ecohydrologic processes is primarily qualitative. We provide detailed, extensive data quantifying the effects of contrasting slope/aspect on the soil physical environment and document the implications of those differences on ecohydrological processes. The study site, Johnston Draw, is located in the Reynolds Creek Experimental Watershed and CZO in southwest Idaho, USA (43° latitude). Johnston Draw flows over granitic bedrock nearly due east, resulting in steep (25 to 40°) side slopes oriented north-south. At the study elevation (1600 m) approximately 50% of the annual precipitation is snow. We measured meteorological variables, snow depth, soil water (SW) and temperature (ST) at three paired locations for two years. Each soil pair consisted of depth profiles from 5 cm to bedrock measured hourly which were supplemented with periodic extensive measurements. Hourly photographs were taken at two of the pairs for one year. Streamflow is monitored at the Johnston Draw outlet and precipitation was measured at stations at the topographic bottom and top of the watershed. Geophysical data were collected in a transect across both slopes. The ST was warmer all year on the south-facing slope, with a mean annual difference of 5°C. This ST difference is effectively equivalent to a 1000 m elevation difference in Reynolds Creek. Despite clear differences in evaporative demand and the timing of spring "green up", the timing of summer SW decline is similar on both slopes. Deeper soil on north-facing slopes resulted in more plant available water and a longer growing season, which is reflected in the vegetation. Geophysical data indicate much deeper weathering on the

  5. 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

  6. 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.

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

    PubMed Central

    Matthis, Jonathan Samir; Fajen, Brett R.

    2013-01-01

    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. PMID:23658204

  8. 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.

  9. 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. PMID:23372749

  10. 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

  11. STUDY OF TURBULENT ENERGY OVER COMPLEX TERRAIN: STATE, 1978

    EPA Science Inventory

    The complex structure of the earth's surface influenced atmospheric parameters pertinent to modeling the diffusion process during the 1978 'STATE' field study. The Information Theory approach of statistics proved useful for analyzing the complex structures observed in the radiome...

  12. An Improved Multi-Scale Modeling Framework for WRF over Complex Terrain

    NASA Astrophysics Data System (ADS)

    Wiersema, D. J.; Lundquist, K. A.; Chow, F. K.

    2014-12-01

    Atmospheric modelers continue to push towards higher resolution simulations of the planetary boundary layer. As resolution is refined, the resolved terrain slopes increase. Atmospheric models using terrain-following coordinates, such as the Weather Research and Forecasting (WRF) model, suffer from numerical errors since steep terrain slopes lead to grid skewness, resulting in model failure. One solution to this problem is the use of an immersed boundary method, which uses a non-conforming grid, for simulations over complex terrain. Our implementation of an immersed boundary method in WRF, known as WRF-IBM, was developed for use at the micro-scale and has been shown to accurately simulate flow around complex topography, such as urban environments or mountainous terrain. The research presented here describes our newly developed framework to enable concurrently run multi-scale simulations using the WRF model at the meso-scale and the WRF-IBM model at the micro-scale. WRF and WRF-IBM use different vertical coordinates therefore it is not possible to use the existing nesting framework to pass lateral boundary conditions from a WRF parent domain to a WRF-IBM nested domain. Nesting between WRF and WRF-IBM requires "vertical grid nesting", meaning the ability to pass information between domains with different vertical levels. Our newly implemented method for vertical grid nesting, available in the public release of WRFv3.6.1, allows nested domains to utilize different vertical levels. Using our vertical grid nesting code, we are currently developing the ability to nest a domain using IBM within a domain using terrain-following coordinates. Here we present results from idealized cases displaying the functionality of the multi-scale nesting framework and the advancement towards multi-scale meteorological simulations over complex terrain.

  13. Quasi-analytical treatment of spatially averaged radiation transfer in complex terrain

    NASA Astrophysics Data System (ADS)

    LöWe, H.; Helbig, N.

    2012-10-01

    We provide a new quasi-analytical method to compute the subgrid topographic influences on the shortwave radiation fluxes and the effective albedo in complex terrain as required for large-scale meteorological, land surface, or climate models. We investigate radiative transfer in complex terrain via the radiosity equation on isotropic Gaussian random fields. Under controlled approximations we derive expressions for domain-averaged fluxes of direct, diffuse, and terrain radiation and the sky view factor. Domain-averaged quantities can be related to a type of level-crossing probability of the random field, which is approximated by long-standing results developed for acoustic scattering at ocean boundaries. This allows us to express all nonlocal horizon effects in terms of a local terrain parameter, namely, the mean-square slope. Emerging integrals are computed numerically, and fit formulas are given for practical purposes. As an implication of our approach, we provide an expression for the effective albedo of complex terrain in terms of the Sun elevation angle, mean-square slope, the area-averaged surface albedo, and the ratio of atmospheric direct beam to diffuse radiation. For demonstration we compute the decrease of the effective albedo relative to the area-averaged albedo in Switzerland for idealized snow-covered and clear-sky conditions at noon in winter. We find an average decrease of 5.8% and spatial patterns which originate from characteristics of the underlying relief. Limitations and possible generalizations of the method are discussed.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. An Experimental Investigation on the Wake Interference of Multiple Wind Turbines over Complex Terrains

    NASA Astrophysics Data System (ADS)

    Hu, Hui; Yang, Zifeng; Ozbay, Ahmet; Sarkar, Partha

    2011-11-01

    We report an experimental study to investigate the wake interferences of multiple wind turbines sited over complex terrains in order to elucidate underlying physics to explore/optimize design paradigms of wind turbines sited over complex terrains for higher power yield and better durability. The experiments were conducted in a wind tunnel with an array of wind turbine models sited over a flat (baseline case) and complex terrains with non-homogenous surface winds. In addition to measuring dynamic wind loads (both forces and moments) and the power outputs of the wind turbine models, advanced flow diagnostic techniques such as digital Particle Image Velocimetry (PIV) will be used to conduct detailed flow field measurements to quantify the flow characteristics of the surface winds and wake interferences among multiple wind turbines over flat (baseline case) and complex terrains. The detailed flow field measurements were correlated with the wind load measurements to elucidate the underlying physics associated with turbine power generation and fatigue loads acting on wind turbines.

  20. POWER PLANT STACK PLUMES IN COMPLEX TERRAIN: AN APPRAISAL OF CURRENT RESEARCH

    EPA Science Inventory

    This report reviews the literature of scientific studies of the behavior of stack plumes from fossil-fueled electric power plants in complex (hilly or mountainous) terrain. Non-conservative chemical transformation and depletion, and conservative transport and diffusion of polluta...

  1. POWER PLANT STACK PLUMES IN COMPLEX TERRAIN. DATA ANALYSIS AND CHARACTERIZATION OF PLUME BEHAVIOR

    EPA Science Inventory

    Aerometric data were collected during 16 months in the vicinity of the coal-fired Clinch River Power Plant, located in the complex terrain of southwestern Virginia. Statistical analyses of SO2, NO, and NO sub x concentrations at eight fixed monitoring sites revealed significant d...

  2. FLUID MODELING DEMONSTRATION OF GOOD-ENGINEERING-PRACTICE STACK HEIGHT IN COMPLEX TERRAIN

    EPA Science Inventory

    A demonstration study using fluid modeling to determine the good-engineering-practice (GEP) stack height for a power plant installation in complex terrain is discussed. The site chosen for this demonstration study was the Clinch River Power Plant in southwestern Virginia, and a 1...

  3. COMPARISON OF UNITED STATES AND RUSSIAN COMPLEX TERRAIN DIFFUSION MODELS DEVELOPED FOR REGULATORY APPLICATIONS

    EPA Science Inventory

    The theoretical bases and computational techniques are presented for U.S. and Russian complex terrain diffusion models developed for engineering applications. hile the U.S. model is based on the modified Gaussian diffusion model, the Russian model is based on the analytical appro...

  4. Some simple improvements to an emergency response model for use in complex coastal terrain

    SciTech Connect

    Miller, N.L.

    1992-06-01

    The MACHWIND model (Meyers 1989) is one of a group of models used to compute regional wind fields from tower wind data and/or vertical wind profiles. The wind fields are in turn used to calculate atmospheric diffusion, to guide emergency responses. MACHWIND has performed acceptably in uniform terrain under steady, well mixed conditions. However, extension of the model to more complex situations is problematic. In coastal, hilly terrain like that near Vandenberg Air Force Base (VAFB) in southern California, calculations of the wind field can be enhanced significantly by several modifications to the original code. This report highlights the structure of MACHWIND and details the enhancements that were implemented.

  5. AIR POLLUTION AND TERRAIN AERODYNAMICS: A REVIEW OF FLUID MODELING STUDIES AT THE EPA (ENVIRONMENTAL PROTECTION AGENCY) FLUID MODELING FACILITY

    EPA Science Inventory

    A review is given of recent fluid modeling studies conducted at the EPA Fluid Modeling Facility of flow and diffusion in complex terrain. Estimates are given for the ratio of the maximum concentration on a hill surface to the maximum concentration in the absence of the hill. The ...

  6. 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.

  7. Quasi-analytical treatment of spatially averaged radiation transfer in complex terrain

    NASA Astrophysics Data System (ADS)

    Löwe, H.; Helbig, N.

    2012-04-01

    We provide a new quasi-analytical method to compute the topographic influence on the effective albedo of complex topography as required for meteorological, land-surface or climate models. We investigate radiative transfer in complex terrain via the radiosity equation on isotropic Gaussian random fields. Under controlled approximations we derive expressions for domain averages of direct, diffuse and terrain radiation and the sky view factor. Domain averaged quantities are related to a type of level-crossing probability of the random field which is approximated by longstanding results developed for acoustic scattering at ocean boundaries. This allows us to express all non-local horizon effects in terms of a local terrain parameter, namely the mean squared slope. Emerging integrals are computed numerically and fit formulas are given for practical purposes. As an implication of our approach we provide an expression for the effective albedo of complex terrain in terms of the sun elevation angle, mean squared slope, the area averaged surface albedo, and the direct-to-diffuse ratio of solar radiation. As an application, we compute the effective albedo for the Swiss Alps and discuss possible generalizations of the method.

  8. 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

  9. Atmospheric studies in complex terrain: executive summary. Technical progress report, FY-1979 through FY-1983

    SciTech Connect

    Gudiksen, P.H.; Dickerson, M.H.

    1983-08-01

    In 1978, the Office of Health and Environmental Research of the Assistant Secretary for Environment in the Department of Energy developed a program aimed specifically at atmospheric studies in complex terrain - ASCOT. The ASCOT program was designed to develop the technology needed to assess atmospheric properties and the impact of energy sources on air quality in areas of complex terrain. The ASCOT team is composed of scientists from DOE national laboratories, other federal laboratories, and university programs. To initiate the program, each participating laboratory and university was asked to redirect funds into an area focusing on research that involved atmospheric boundary layer flow subject to interactions with complicated underlying terrain. The two broad objectives under which the program was organized are: to improve fundamental knowledge of transport and dispersion processes in complex terrain; and to utilize this improved insight into the physics of terrain dominated flows to provide a methodology for performing air quality assessments. The initial focus of the ASCOT program has been on the transport and dispersion of pollutants entrained in or near nocturnal drainage flows. This phenomenon was selected on the basis of its importance for transporting pollutants from energy related facilities to population or agricultural centers that are generally situated within valleys. The Geysers geothermal area in northern California, a large geothermal power producing region situated within the coastal-mountain range was chosen as the primary field experimental area. Three series of major field experiments were conducted in this area; while smaller scale studies were carried out at Rattlesnake Mountain near Richland, Washington, Corral Gulch in western Colorado, and on Parajarito Mountain near Los Alamos, New Mexico to evaluate cold air drainage on relatively simple slopes. 1 figure, 4 tables.

  10. Explicit validation of a surface shortwave radiation balance model over snow-covered complex terrain

    NASA Astrophysics Data System (ADS)

    Helbig, N.; Löwe, H.; Mayer, B.; Lehning, M.

    2010-09-01

    A model that computes the surface radiation balance for all sky conditions in complex terrain is presented. The spatial distribution of direct and diffuse sky radiation is determined from observations of incident global radiation, air temperature, and relative humidity at a single measurement location. Incident radiation under cloudless sky is spatially derived from a parameterization of the atmospheric transmittance. Direct and diffuse sky radiation for all sky conditions are obtained by decomposing the measured global radiation value. Spatial incident radiation values under all atmospheric conditions are computed by adjusting the spatial radiation values obtained from the parametric model with the radiation components obtained from the decomposition model at the measurement site. Topographic influences such as shading are accounted for. The radiosity approach is used to compute anisotropic terrain reflected radiation. Validations of the shortwave radiation balance model are presented in detail for a day with cloudless sky. For a day with overcast sky a first validation is presented. Validation of a section of the horizon line as well as of individual radiation components is performed with high-quality measurements. A new measurement setup was designed to determine terrain reflected radiation. There is good agreement between the measurements and the modeled terrain reflected radiation values as well as with incident radiation values. A comparison of the model with a fully three-dimensional radiative transfer Monte Carlo model is presented. That validation reveals a good agreement between modeled radiation values.

  11. Design of a complex terrain meteorological monitoring program for real-time air quality modeling analysis

    SciTech Connect

    Militana, L.M.; Karpovich, R.; Cimorelli, A.; Scire, J.S.

    1998-12-31

    A multi-station meteorological monitoring program has been designed and developed for a complex terrain air quality modeling study. The purpose of the program is to collect representative on site data as input to complex terrain air quality models and to predict in real-time the potential air quality impact of a rotary kiln incinerator The program is a state-of the science design using the best science air quality dispersion models (CALMET/CALPUFF) and meteorological monitoring equipment (RASS/SODAR Systems monostatic and phased array and multiple towers). The real-time meteorological monitoring program consisted of two monitoring stations using meteorological towers and Doppler SODAR and phased array RASS systems to determine the temperature and wind profile of the atmospheric boundary layer. The primary station were located adjacent to the site and consisted of a 150 ft meteorological tower and RASS/SODAR system. The secondary station was located approximately 1,600 meters northeast of the site and consisted of a 10 meter tower and a SODAR system. These monitoring stations provided 15-minute values of wind speed, wind direction, ambient temperature, and thermal and mechanical turbulence measurements for use in a complex terrain air quality modeling study and a real-time modeling system.

  12. 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.

  13. Seasonal evolution of ecohydrological controls on land surface temperature over complex terrain

    NASA Astrophysics Data System (ADS)

    Xiang, Tiantian; Vivoni, Enrique R.; Gochis, David J.

    2014-05-01

    The spatiotemporal distribution of Land Surface Temperature (LST) is linked to the partitioning of the coupled surface water and energy budgets. In watersheds with a strong seasonality in precipitation and vegetation cover, the temporal evolution of LST patterns are a signature of the interactions between the land surface and atmosphere. Nevertheless, few studies have sought to understand the topographical and ecohydrological controls on LST in regions of complex terrain. Numerical watershed models, tested against spatially distributed field and remote sensing data, can aid in linking the seasonal evolution of LST to meteorology, terrain, soil, and vegetation. In this study, we use a distributed hydrologic model to explore LST patterns in a semiarid mountain basin during the transition from a dry spring to the wetter North American monsoon (NAM). By accounting for vegetation greening through remotely sensed parameters, the model reproduces LST and surface soil moisture observations derived from ground, aircraft, and satellite platforms with good accuracy at individual sites and as spatial basin patterns. Distributed simulations reveal how LST varies with elevation, slope, and aspect and the role played by the seasonal vegetation canopy in cooling the land surface and increasing the spatial variability in LST. As a result, LST is shown to track well with ecosystem-specific changes in vegetation cover, evapotranspiration, and soil moisture during the NAM. Furthermore, vegetation greening is shown to modulate the spatial heterogeneity of LST during the NAM that should be considered in subsequent atmospheric studies in regions of complex terrain.

  14. 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.

  15. 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

  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. Measurement of advection of CO2 over grasslands in complex terrain in the Alps

    NASA Astrophysics Data System (ADS)

    Zhao, Peng; Hammerle, Albin; Wohlfahrt, Georg

    2015-04-01

    The role of advection is often ignored in the estimation of net ecosystem exchange (NEE) of CO2 in ecosystems. However, some studies reported that more realistic estimates of night-time NEE could be gathered if horizontal and vertical advections are included. While most of previous advection experiments have been conducted in forest ecosystems, grassland ecosystems have a great advantage as measurements of advection can be realised with smaller infrastructure and thus less experimental effort. In a preliminary simplified study, advection showed an important contribution to NEE during night time at a sub-alpine grassland site. This three-year program is focused on the role of advection for NEE of grassland ecosystems in complex terrain in the Alps. We are going to carry out field campaigns at four sites which cover a range of terrain types typical for mountains with varying degrees of complexity, including a valley-bottom site, a steep-slope site, a mixed-terrain site, and an undulating-terrain site. Observations will take place in a notional control volume with a length varying from 50 m to 5 m at each site in order to quantify the effects of horizontal spatial scale on advection estimates. The observations at each site include vertical flux of CO2 measured by eddy-covariance technique, horizontal and vertical advections of CO2 calculated from the measurement of wind components and CO2 gradients, and NEE measured by chambers. Among all, the measurement of the horizontal advection of CO2 needs many efforts because of small-scale variability in sources/sinks of CO2. We are going to use tubes with multiple inlets, which allows sampling at multiple positions across the faces at three heights of the control volume. Thus, we would be able to quantify the contribution of advection to NEE at different grassland sites situated in complex terrain in the Alps, and to quantify the effect of spatial scale of advection measurements with a given experimental setup and accuracy on

  19. Extreme Daily Rainfalls U An Example of Their Gis Analysis In A Complex Terrain

    NASA Astrophysics Data System (ADS)

    Tolasz, R.; Brazdil, R.; Striz, M.

    Very complex relief of the Czech Republic (with altitudes between 199 m a.s.l. and 1602 m a.s.l.) influences significantly spatial distribution of precipitation totals, in- cluding extreme daily rainfalls. There is a problem how to take in consideration this fact in its mapping. The GIS method with using Spatial Analyst part of ArcView al- low to solve this question. It is documented on the analysis of spatial distribution of 18 cases of daily extreme rainfalls (at least one station with daily total over 150 mm) over the territory of the Czech Republic in the period 1961-2000. The main idea of the proposed method is construction of virtual terrain for spatial rainfall analysis. That vir- tual terrain is used for regression calculation of daily rainfall from station location to horizontal 500 x 500 meters grid. The correction to real terrain is last part of method. GIS shapefiles as output can be used for further analysis of each day (for example, calculation of area precipitation totals for hydrologic or synoptic purposes).

  20. Numerical investigation into effects of complex terrain on spatial and temporal variability of precipitation

    SciTech Connect

    Stalker, J.R.; Bossert, J.E.; Reisner, J.M.

    1998-12-31

    This study is part of an ongoing research effort at Los Alamos to understand the hydrologic cycle at regional scales by coupling atmospheric, land surface, river channel, and groundwater models. In this study the authors examine how local variation of heights of the two mountain ranges representative of those that surround the Rio Grande Valley affects precipitation. The lack of observational data to adequately assess precipitation variability in complex terrain, and the lack of previous work has prompted this modeling study. Thus, it becomes imperative to understand how the local terrain affects snow accumulations and rainfall during winter and summer seasons respectively so as to manage this valuable resource in this semi-arid region. While terrain is three dimensional, simplifying the problem to two dimensions can provide some valuable insight into topographic effects that may exist at various transects across the Rio Grande Valley. The authors induce these topographic effects by introducing variations in heights of the mountains and the width of the valley using an analytical function for the topography. The Regional Atmospheric Modeling System (RAMS) is used to examine these effects.

  1. Evaluation and development of a high resolution wind model for wildfire applications in complex terrain

    NASA Astrophysics Data System (ADS)

    Wagenbrenner, Natalie Suzanne

    Accurate modeling of near-surface winds is important for wildfire applications, including wildfire behavior and spread as well as post-fire processes, including wind-driven dust and ash emissions from burned soils. The work presented in this dissertation investigates a high resolution wind model for use in wildfire applications in complex terrain and includes (1) an observational field study to collect high resolution surface wind data from two types of complex terrain features; (2) use of these observed data to evaluate a suite of Numerical Weather Prediction (NWP) model near surface wind predictions and dynamical downscaling of those predictions with a high resolution wind model; and (3) field quantification of wind erosion from soils burned by wildfire. Unique flow features, including upslope, downslope, and synoptically-driven flow events were presented for an isolated mountain and a steep river canyon. Evaluations with these observed datasets indicated that NWP surface winds can be improved in complex terrain via dynamic downscaling with a high resolution wind model, WindNinja, so long as the average approach flow to the area of interest can be reasonably defined (i.e., the initial wind field must be appropriately defined). The biggest improvements occurred during periods of synoptically-driven events when observed winds speeds exceeded 10 m s-1. Results from the post-fire field campaign demonstrated that post-fire landscapes can be significant sources of particulates and that dust emissions can persist for up to a year post-fire. Data collected during this study represents the first real-time measurements of PM10 fluxes from a burned landscape. These data will be useful in evaluating windblown dust emissions algorithms applied to burned landscapes.

  2. An evaluation of the AMS/EPA Regulatory Model (AERMOD) complex terrain algorithms

    SciTech Connect

    Garrison, M.; Sherwell, J.

    1997-12-31

    A draft version of the AMS/EPA Regulatory Model (AERMOD) was made available to the public at the Sixth Conference on Air Quality Modeling, in August 1995. The model was also made available to beta testers as part of AMS and EPA`s on-going efforts to thoroughly evaluate the model prior to delivering a completed model to EPA for regulatory use. Since that time, AERMOD has undergone extensive diagnostic evaluation and some changes, with the goal of finalizing the model and subjecting it to performance evaluations with independent data bases prior to releasing the model for general use. The present study documented in this paper was initiated in the beta-testing program and has been continued under the sponsorship of the Maryland Department of Natural Resources Power Plant Research Program (PPRP). The study consists of an in-depth comparison of the complex terrain component of AERMOD, with a focus on neutral and stable-case impacts. Hourly concentration comparisons are made for a wide spectrum of synthesized meteorological conditions and for a broad range of stack characteristics representative of Maryland power plant stacks, between AERMOD predictions and predictions made by other available complex terrain models. The other models included the screening models RTDM and COMPLEX-I, and EPA`s refined CTDM. Predictions are also made and comparisons compiled based on alternative model options within AERMOD. The paper addresses model component-specific impacts in the case of CTDM and AERMOD, i.e. the LIFT and WRAP components representing flow above and around terrain, respectively, and uses graphical representation of model predictions extensively to illustrate model predictions. The paper describes the study approach, provides tabular and graphical summaries of the model and component-specific results, and offers some interpretations of model performance based on these intercomparisons.

  3. Finite element simulation of a local scale air quality model over complex terrain

    NASA Astrophysics Data System (ADS)

    Oliver, A.; Montero, G.; Montenegro, R.; Rodríguez, E.; Escobar, J. M.; Perez-Foguet, A.

    2012-05-01

    In this paper we propose a finite element method approach for modelling the air quality in a local scale over complex terrain. The area of interest is up to tens of kilometres and it includes pollutant sources. The proposed methodology involves the generation of an adaptive tetrahedral mesh, the computation of an ambient wind field, the inclusion of the plume rise effect in the wind field, and the simulation of transport and reaction of pollutants. We apply our methodology to simulate a fictitious pollution episode in La Palma island (Canary Island, Spain).

  4. PIV measurements and data accuracy analysis of flow in complex terrain

    NASA Astrophysics Data System (ADS)

    Yao, Rentai; Hao, Hongwei; Qiao, Qingdang

    2000-10-01

    In this paper velocity fields and flow visualization in complex terrain in an environmental wind tunnel have been measured using PIV. In addition, it would be useful to appraise the PIV data by comparing the PIV results with those obtained from the well- established point measurement methods, such as constant temperature anemometry (CTA) and Dantec FlowMaster, in order to verify the accuracy of PIV measurements. The results indicate that PIV is a powerful tool for velocity measurements in the environmental wind tunnel.

  5. 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

  6. 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

  7. 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.

  8. Dispersion of particles in complex terrain: comparisons between WRF LES and simulations using different PBL schemes

    NASA Astrophysics Data System (ADS)

    Xue, L.; Kosovic, B.; Tessendorf, S. A.; Rasmussen, R.

    2015-12-01

    A key process in wintertime orographic cloud seeding using ground-based generators is the dispersion of silver iodide particles released from the generators in the mountainous area. The dispersion features determine the targeting efficiency and ultimately the seeding effect on the ground under favorable seeding conditions. Previous field experiments showed that the silver iodide plumes were narrow (spread angle was around 20 degrees) and were confined within the mountainous boundary layer (usually lower than 1 km AGL). The numerical simulation of the particle dispersion in complex terrain using weather models is challenging due to the stable atmosphere in winter, the unresolved terrain-flow interaction, and the inherent numerical diffusion close to the source point in the Eulerian framework. A recent study by Xue et al. (2014) showed that Large Eddy Simulation (LES) of the particle dispersion in complex terrain with grid spacing of 100 m could reproduce most observed features while simulations using PBL schemes with 500 m grid spacing had difficulty reproducing the vertical dispersion. This study will simulate the same case using the Weather Research and Forecasting (WRF) model in LES mode and with several PBL schemes. The differences between the LES-simulated dispersion results and the PBL results will be analyzed and presented. Especially, the difference attributed to the unrepresented sub-grid scale (SGS) topography information in the PBL will be studied in detail. The ultimate goal of this study is to incorporate the dispersion due to turbulent kinetic energy induced by SGS topography into the existing PBL schemes to better simulate the process in mountainous regions.

  9. 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.

  10. Impact of spatial heterogeneity of meteorological forcing on soil moisture redistribution over complex terrain

    NASA Astrophysics Data System (ADS)

    Fernandez, S.; Simoni, S.; Parlange, M.

    2010-09-01

    An experiment was designed in order to capture the spatial heterogeneity of meteorological variables over a complex terrain. The study area is located in the suisse Alps, close to the Gd-St-Bernard pass, in the upper part of the Val de Ferret. The catchment has a total area of 20 km2 and the altitude ranges from 1777 m to 3206 m. Steep complex terrain, covered with snow from November to May and deep gullies are the main features of the study area. 15 meteorological stations equipped with soil sensors (moisture, suction and temperature) were deployed into a network spread over the study area to capture the heterogeneity of the meteorological forcing relevant to evapotranspiration processes and its impact on soil moisture distribution. A soil characterization was also carried out to complement the understanding of soil moisture redistribution processes. Results assess that soil water content heterogeneity is highly affected not only by spatial variability of soil characteristics and morphology but also of precipitation.

  11. The Granite Mountain Atmospheric Sciences Testbed (GMAST): A Facility for Long Term Complex Terrain Airflow Studies

    NASA Astrophysics Data System (ADS)

    Zajic, D.; Pace, J. C.; Whiteman, C. D.; Hoch, S.

    2011-12-01

    This presentation describes a new facility at Dugway Proving Ground (DPG), Utah that can be used to study airflow over complex terrain, and to evaluate how airflow over a mountain barrier affects wind patterns over adjacent flatter terrain. DPG's primary mission is to conduct testing, training, and operational assessments of chemical and biological weapon systems. These operations require very precise weather forecasts. Most test operations at DPG are conducted on fairly flat test ranges having uniform surface cover, where airflow patterns are generally well-understood. However, the DPG test ranges are located alongside large, isolated mountains, most notably Granite Mountain, Camelback Mountain, and the Cedar Mountains. Airflows generated over, or influenced by, these mountains can affect wind patterns on the test ranges. The new facility, the Granite Mountain Atmospheric Sciences Testbed, or GMAST, is designed to facilitate studies of airflow interactions with topography. This facility will benefit DPG by improving understanding of how mountain airflows interact with the test range conditions. A core infrastructure of weather sensors around and on Granite Mountain has been developed including instrumented towers and remote sensors, along with automated data collection and archival systems. GMAST is expected to be in operation for a number of years and will provide a reference domain for mountain meteorology studies, with data useful for analysts, modelers and theoreticians. Visiting scientists are encouraged to collaborate with DPG personnel to utilize this valuable scientific resource and to add further equipment and scientific designs for both short-term and long-term atmospheric studies. Several of the upcoming MATERHORN (MountAin TERrain atmospHeric mOdeling and obseRvatioNs) project field tests will be conducted at DPG, giving an example of GMAST utilization and collaboration between DPG and visiting scientists.

  12. A complex terrain dispersion model for regulatory applications at the Westvaco luke mill

    NASA Astrophysics Data System (ADS)

    Hanna, Steven R.; Egan, Bruce A.; Vaudo, Cosmo J.; Curreri, Anthony J.

    A data set for studying transport and dispersion in complex terrain was collected at the Westvaco Corporation's Luke Mill, located in the Potomac River valley in western Maryland. Meteorological analyses indicate very strong channeling of winds and the presence of strong inversions and wind shears in a shallow layer at the height of the surrounding mountaintops (300 m above the valley floor). Wind velocities observed near the valley floor are unrepresentative of wind velocities at plume height. Observed turbulence intensities at plume height are about twice as large as those observed over flat terrain. Standard stability classification schemes generally underestimate plume dispersion at this site. When high 3-h and 24-h average SO 2 concentrations are observed, winds are usually light and an inversion is present. These instances of relatively high concentrations are often associated with periods when the wind shifts direction 180° from up-valley to down-valley or vice versa, and the nearly stagnant polluted air mass blows against the mountainsides. A dispersion model was developed that is Gaussian in form but uses observed meteorological data to the maximum extent possible. For example, observed turbulence intensities at plume height are used to estimate dispersion. Plume impaction on terrain is calculated if the plume height is below a critical height dependent on the Hill Froude number. Evaluation of the model with the full 2-y data set shows that it can estimate the second highest 3-h and 24-h average concentrations (of regulatory significance) with a mean bias of less than 7%.

  13. TopoSCALE v.1.0: downscaling gridded climate data in complex terrain

    NASA Astrophysics Data System (ADS)

    Fiddes, J.; Gruber, S.

    2014-02-01

    Simulation of land surface processes is problematic in heterogeneous terrain due to the the high resolution required of model grids to capture strong lateral variability caused by, for example, topography, and the lack of accurate meteorological forcing data at the site or scale it is required. Gridded data products produced by atmospheric models can fill this gap, however, often not at an appropriate spatial resolution to drive land-surface simulations. In this study we describe a method that uses the well-resolved description of the atmospheric column provided by climate models, together with high-resolution digital elevation models (DEMs), to downscale coarse-grid climate variables to a fine-scale subgrid. The main aim of this approach is to provide high-resolution driving data for a land-surface model (LSM). The method makes use of an interpolation of pressure-level data according to topographic height of the subgrid. An elevation and topography correction is used to downscale short-wave radiation. Long-wave radiation is downscaled by deriving a cloud-component of all-sky emissivity at grid level and using downscaled temperature and relative humidity fields to describe variability with elevation. Precipitation is downscaled with a simple non-linear lapse and optionally disaggregated using a climatology approach. We test the method in comparison with unscaled grid-level data and a set of reference methods, against a large evaluation dataset (up to 210 stations per variable) in the Swiss Alps. We demonstrate that the method can be used to derive meteorological inputs in complex terrain, with most significant improvements (with respect to reference methods) seen in variables derived from pressure levels: air temperature, relative humidity, wind speed and incoming long-wave radiation. This method may be of use in improving inputs to numerical simulations in heterogeneous and/or remote terrain, especially when statistical methods are not possible, due to lack of

  14. Long-range (CAPTEX (Cross-APpalachian Tracer EXperiment)) and complex terrain (ASCOT (Atmospheric Studies of COmplex Terrain)) perfluorocarbon tracer studies

    SciTech Connect

    Jeffter, J.L.; Yamada, T.; Dietz, R.N.

    1986-01-01

    Perfluorocarbon tracer (PFT) technology, consisting of tracers, samplers, and analytical equipment, has been deployed in numerous meteorological experiments for the verification of long-range and complex terrain transport and dispersion models. The CAPTEX (Cross-APpalachain Tracer EXperiment) ''83 was conducted from mid-September through October 1983, in which seven 3-h tracer releases (5 from Dayton, Ohio, and 2 from Sudbury, Ontario) were made of a single PFT. Ground sampling occurred at 80 sites in the northeastern US and southeastern Canada at distances of 300 to 1100 km from the release sites, with a total of 3000 samples collected. Seven aircraft gathered 1600 crosswind and vertical spiral samples at distance of 200 to 900 km from the release sites. Peak ground concentrations of over 30 times background and peak aircraft values of over 150 times background were measured at the most distant sites; some typical results are shown. The branching atmospheric trajectory (BAT) long-range transport was described. The model-calculated maximum ground level PFT concentrations were compared with the measured concentration isopleths as well as through the use of scatter diagrams of concentrations, spatial errors, and frequency of space- and time-averaged concentrations. The average spatial error found for each of the 7 releases ranged from 1.3/sup 0/ to 1.7/sup 0/ lat. The crosswind standard deviations of aircraft traverses at 600 to 800 km downwind varied from 12 to 20 km which corresponded to 1.0/sup 0/ to 1.6/sup 0/ lat., indicating that the model was accurate to within one standard deviation of the real-time tracer profiles. On average, for the 7 runs, 50% of the model-calculated concentrations were within a factor of 20 of the observations, indicating that, in general, 1/sup 0/ lat. shifts can easily cause order-of-magnitude changes in observed concentrations.

  15. Transitional dispersive scenarios driven by mesoscale flows on complex terrain under strong dry convective conditions

    NASA Astrophysics Data System (ADS)

    Palau, J. L.; Pérez-Landa, G.; Millán, M. M.

    2009-01-01

    By experimentation and modelling, this paper analyses the atmospheric dispersion of the SO2 emissions from a power plant on complex terrain under strong convective conditions, describing the main dispersion features as an ensemble of "stationary dispersive scenarios" and reformulating some "classical" dispersive concepts to deal with the systematically monitored summer dispersive scenarios in inland Spain. The results and discussions presented arise from a statistically representative study of the physical processes associated with the multimodal distribution of pollutants aloft and around a 343-m-tall chimney under strong dry convective conditions in the Iberian Peninsula. This paper analyses the importance of the identification and physical implications of transitional periods for air quality applications. The indetermination of a transversal plume to the preferred transport direction during these transitional periods implies a small (or null) physical significance of the classical definition of horizontal standard deviation of the concentration distribution.

  16. Concatenated non-stationary dispersive scenarios on complex terrain under summer conditions

    NASA Astrophysics Data System (ADS)

    Palau, J. L.; Pérez-Landa, G.; Millán, M. M.

    2008-06-01

    The results and discussions presented in this paper arise from a statistically representative study of the physical processes associated with the multimodal distribution of pollutants aloft and around a 343-m-tall chimney under summer conditions in the Iberian Peninsula. The indetermination of a transversal plume to the preferred transport direction during transitional periods implies a small (or null) physical significance of the classical definition of horizontal standard deviation of the concentration distribution. By experimentation and modelling, this paper analyses the atmospheric dispersion of the SO2 emissions from a power plant on complex terrain, describing the main dispersion features as an ensemble of "stationary dispersive scenarios" and reformulating some "classical" dispersive concepts to deal with the systematically monitored summer dispersive scenarios in inland Spain.

  17. Soil CO2 Efflux Variability in Complex Terrain: Towards Estimation of Watershed-Level Rates

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

    Soil CO2 efflux is a primary component of ecosystem respiration and a key determinant of net ecosystem production (NEP). One obstacle to understanding/predicting the heterogeneity of soil CO2 efflux is the variability in patterns of soil physical and biogeochemical processes imposed by topography, particularly in complex terrain. Extrapolating from single- or multiple-point measurements to watershed-scale efflux estimates requires an understanding of the spatial variability of environmental variables (e.g. soil temperature, vegetation, substrate, soil physical properties). Additionally, soil CO2 efflux can vary at hourly, daily, and seasonal time scales as a result of the interaction among these variables, including the lateral redistribution of soil water. We examined the relationships between topographically-derived indices (e.g., upslope accumulated area, topographic indices, radiation indices) and the space/time variability of soil CO2 efflux to explore the concept of biogeochemically similar areas (BSAs) for estimating watershed-scale soil CO2 efflux. We suggest that characteristic dynamics of BSAs can be used to extrapolate from benchmark data collection locations to larger areas of the landscape and indicate watershed-level response to changes in soil temperature, soil water content, and precipitation. We use both discrete and continuous field-based observations of soil CO2 efflux from a 380-ha watershed in the Tenderfoot Creek Experimental Forest (TCEF), a montane conifer forest characteristic of sub-alpine ecosystems of the northern Rocky Mountains. These observations, in association with terrain analysis and process-based understanding, are used to characterize and quantify the spatial and temporal variability of soil CO2 efflux. Based on efflux measurements collected during two growing seasons (2005, 2006), there was moderate correlation between upslope accumulated area and rates of soil CO2 efflux across 18 diverse upland areas of the watershed (r2

  18. Bayesian Inference aided analog downscaling for near-surface winds in complex terrain

    NASA Astrophysics Data System (ADS)

    Manor, Alon; Berkovic, Sigalit

    2015-10-01

    Assessing atmospheric boundary layer flows in complex terrain for short-range real-time applications demands fast and reliable downscaling from coarser-resolution meteorological data to the relevant scale. An ideal statistical downscaling numerical experiment was performed for surface winds above complex terrain in Israel's northern Negev desert region. Dynamical downscaling have been performed by the WRF model to create a historical database by the following two sets. The first set used 5 nested domains from 40.5 km to 0.5 km. The second set used 3 nested domains ranging from 40.5 km to 4.5 km. The 4.5 km data (stage 2) was defined as predictors while data on 0.5 km (stage 1) served as predictands for statistical downscaling. Two statistical downscaling algorithms: minimal distance analog and a Bayesian inference aided analog (hereafter Bayesian algorithm) were tested by the above data. Unlike most analog algorithms, the Bayesian algorithm refers to the probability to get the best analog instead of the minimal differences between predictands. The comparison of the two algorithms shows that the Bayesian approach yields improved results. The Bayesian algorithm reproduces the 0.5 km resolution dynamically downscaled surface winds with an average absolute direction difference of 43 and 20 for calm winds and moderate/strong winds respectively. Its average wind speed error is ~ 1.1 ms- 1. ~ 40 days are sufficient to create a representative database. Given the database, the procedure is extremely fast (a few seconds) and easy to operate, which makes it suitable for real-time non-expert fast-response applications.

  19. 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.

  20. Coevolution of Down-Valley Flow and the Nocturnal Boundary Layer in Complex Terrain

    NASA Astrophysics Data System (ADS)

    Pinto, J. O.; Parsons, D. B.; Brown, W. O. J.; Cohn, S.; Chamberlain, N.; Morley, B.

    2006-10-01

    An enhanced National Center for Atmospheric Research (NCAR) integrated sounding system (ISS) was deployed as part of the Vertical Transport and Mixing (VTMX) field experiment, which took place in October of 2000. The enhanced ISS was set up at the southern terminus of the Great Salt Lake Valley just north of a gap in the Traverse Range (TR), which separates the Great Salt Lake and Utah Lake basins. This location was chosen to sample the dynamic and thermodynamic properties of the flow as it passes over the TR separating the two basins. The enhanced ISS allowed for near-continuous sampling of the nocturnal boundary layer (NBL) and low-level winds associated with drainage flow through the gap in the TR. Diurnally varying winds were observed at the NCAR site on days characterized by weak synoptic forcing and limited cloud cover. A down-valley jet (DVJ) was observed on about 50% of the nights during VTMX, with the maximum winds usually occurring within 150 m of the surface. The DVJ was associated with abrupt warming at low levels as a result of downward mixing and vertical transport of warm air from the inversion layer above. Several processes were observed to contribute to vertical transport and mixing at the NCAR site. Pulses in the strength of the DVJ contributed to vertical transport by creating localized areas of low-level convergence. Gravity waves and Kelvin Helmholtz waves, which facilitated vertical mixing near the surface and atop the DVJ, were observed with a sodar and an aerosol backscatter lidar that were deployed as part of the enhanced ISS. The nonlocal nature of the processes responsible for generating turbulence in strongly stratified surface layers in complex terrain confounds surface flux parameterizations typically used in mesoscale models that rely on Monin Obukhov similarity theory. This finding has major implications for modeling NBL structure and drainage flows in regions of complex terrain.

  1. The Potential Utility of High Resolution Ensemble Sensitivities During Weak Flow in Complex Terrain

    NASA Astrophysics Data System (ADS)

    Hacker, J.; Wile, S.

    2013-12-01

    Recent expansion in availability of re-locatable near-surface atmospheric observing sensors introduces the question of where placement maximizes gain in forecast accuracy. Here the potential for ensemble sensitivity analysis (ESA) is examined for high-resolution (Δx=4 km) predictions in complex terrain. The primary objective is to determine whether a mesoscale ESA applied at these scales is useful for identifying potential observing locations in weak flow. ESA can be inaccurate when the underlying assumptions of linear dynamics (and Gaussian statistics) are violated, or when the sensitivity cannot be robustly sampled. A case study of a fog event at the Salt Lake City airport (KSLC) provides a useful period for examining these issues, with the additional influence of complex terrain. A realistic upper-air observing network is used in perfect-model ensemble data assimilation experiments, providing the statistics for ESA. Results show that water vapor mixing ratios over KSLC are sensitive to temperature on the first model layer tens of km away, 6 h prior to verification and prior to the onset of fog. Sensitivity 12 h prior is weaker but leads to qualitatively similar results. Temperatures are shown to be a predictor of inversion strength in the Salt Lake basin; the ESA predicts southerly flow and strengthened inversions with warmer temperatures in a few locations. Simple linearity tests show that small perturbations do not lead to the expected forecast change, but larger perturbations do, suggesting that noise can dominate a small perturbation. Assimilating a perfect observation at the maximum sensitivity location produces forecasts more closely agreeing with the ESA. Sampling error evaluation show that similar conclusions can be reached with ensembles as small as 48 members, but smaller ensembles do not produce accurate sensitivity estimates.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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).

  8. 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

  9. Immersed boundary methods for high-resolution simulation of atmospheric boundary-layer flow over complex terrain

    NASA Astrophysics Data System (ADS)

    Lundquist, Katherine Ann

    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

  10. DIURNAL AND SEASONAL PATTERNS OF TEMPERATURE AND WIND FLOW IN THE PLANETARY BOUNDARY LAYER FOR TEN LOCATIONS IN COMPLEX TERRAIN

    EPA Science Inventory

    In support of the Complex Terrain Model Development program, climatological summaries in the form of vertical profiles of wind and temperature were produced from a special computer file of radiosonde data created from twice daily observations recorded at ten National Weather Serv...

  11. 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...

  12. EVALUATION OF THE COMPLEX TERRAIN DISPERSION MODEL AGAINST LABORATORY OBSERVATIONS: NEUTRAL FLOW OVER 2-D AND 3-D HILLS

    EPA Science Inventory

    A comparison is made of the predictions of the Complex Terrain Dispersion Model (CTDM) with wind-tunnel observations of flow and diffusion in a simulated neutral atmospheric boundary layer over two- and three-dimensional hills. The measure used to evaluate the ability of the mode...

  13. 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

  14. 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

  15. Convergent evolution and locomotion through complex terrain by insects, vertebrates and robots.

    PubMed

    Ritzmann, Roy E; Quinn, Roger D; Fischer, Martin S

    2004-07-01

    Arthropods are the most successful members of the animal kingdom largely because of their ability to move efficiently through a range of environments. Their agility has not been lost on engineers seeking to design agile legged robots. However, one cannot simply copy mechanical and neural control systems from insects into robotic designs. Rather one has to select the properties that are critical for specific behaviors that the engineer wants to capture in a particular robot. Convergent evolution provides an important clue to the properties of legged locomotion that are critical for success. Arthropods and vertebrates evolved legged locomotion independently. Nevertheless, many neural control properties and mechanical schemes are remarkably similar. Here we describe three aspects of legged locomotion that are found in both insects and vertebrates and that provide enhancements to legged robots. They are leg specialization, body flexion and the development of a complex head structure. Although these properties are commonly seen in legged animals, most robotic vehicles have similar legs throughout, rigid bodies and rudimentary sensors on what would be considered the head region. We describe these convergent properties in the context of robots that we developed to capture the agility of insects in moving through complex terrain. PMID:18089044

  16. Wind Resource Assessment in Complex Terrain with a High-Resolution Numerical Weather Prediction Model

    NASA Astrophysics Data System (ADS)

    Gruber, Karin; Serafin, Stefano; Grubišić, Vanda; Dorninger, Manfred; Zauner, Rudolf; Fink, Martin

    2014-05-01

    A crucial step in planning new wind farms is the estimation of the amount of wind energy that can be harvested in possible target sites. Wind resource assessment traditionally entails deployment of masts equipped for wind speed measurements at several heights for a reasonably long period of time. Simplified linear models of atmospheric flow are then used for a spatial extrapolation of point measurements to a wide area. While linear models have been successfully applied in the wind resource assessment in plains and offshore, their reliability in complex terrain is generally poor. This represents a major limitation to wind resource assessment in Austria, where high-altitude locations are being considered for new plant sites, given the higher frequency of sustained winds at such sites. The limitations of linear models stem from two key assumptions in their formulation, the neutral stratification and attached boundary-layer flow, both of which often break down in complex terrain. Consequently, an accurate modeling of near-surface flow over mountains requires the adoption of a NWP model with high horizontal and vertical resolution. This study explores the wind potential of a site in Styria in the North-Eastern Alps. The WRF model is used for simulations with a maximum horizontal resolution of 800 m. Three nested computational domains are defined, with the innermost one encompassing a stretch of the relatively broad Enns Valley, flanked by the main crest of the Alps in the south and the Nördliche Kalkalpen of similar height in the north. In addition to the simulation results, we use data from fourteen 10-m wind measurement sites (of which 7 are located within valleys and 5 near mountain tops) and from 2 masts with anemometers at several heights (at hillside locations) in an area of 1600 km2 around the target site. The potential for wind energy production is assessed using the mean wind speed and turbulence intensity at hub height. The capacity factor is also evaluated

  17. 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

  18. 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.

  19. 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

  20. Mesoscale ensemble sensitivity analysis for predictability studies and observing network design in complex terrain

    NASA Astrophysics Data System (ADS)

    Hacker, Joshua

    2013-04-01

    Ensemble sensitivity analysis (ESA) is emerging as a viable alternative to adjoint sensitivity. Several open issues face ESA for forecasts dominated by mesoscale phenomena, including (1) sampling error arising from finite-sized ensembles causing over-estimated sensitivities, and (2) violation of linearity assumptions for strongly nonlinear flows. In an effort to use ESA for predictability studies and observing network design in complex terrain, we present results from experiments designed to address these open issues. Sampling error in ESA arises in two places. First, when hypothetical observations are introduced to test the sensitivity estimates for linearity. Here the same localization that was used in the filter itself can be simply applied. Second and more critical, localization should be considered within the sensitivity calculations. Sensitivity to hypothetical observations, estimated without re-running the ensemble, includes regression of a sample of a final-time (forecast) metric onto a sample of initial states. Derivation to include localization results in two localization coefficients (or factors) applied in separate regression steps. Because the forecast metric is usually a sum, and can also include a sum over a spatial region and multiple physical variables, a spatial localization function is difficult to specify. We present results from experiments to empirically estimate localization factors for ESA to test hypothetical observations for mesoscale data assimilation in complex terrain. Localization factors are first derived for an ensemble filter following the empirical localization methodology. Sensitivities for a fog event over Salt Lake City, and a Colorado downslope wind event, are tested for linearity by approximating assimilation of perfect observations at points of maximum sensitivity, both with and without localization. Observation sensitivity is then estimated, with and without localization, and tested for linearity. The validity of the

  1. 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

  2. Near-Surface Wind Predictions in Complex Terrain with a CFD Approach Optimized for Atmospheric Boundary Layer Flows

    NASA Astrophysics Data System (ADS)

    Wagenbrenner, N. S.; Forthofer, J.; Butler, B.; Shannon, K.

    2014-12-01

    Near-surface wind predictions are important for a number of applications, including transport and dispersion, wind energy forecasting, and wildfire behavior. Researchers and forecasters would benefit from a wind model that could be readily applied to complex terrain for use in these various disciplines. Unfortunately, near-surface winds in complex terrain are not handled well by traditional modeling approaches. Numerical weather prediction models employ coarse horizontal resolutions which do not adequately resolve sub-grid terrain features important to the surface flow. Computational fluid dynamics (CFD) models are increasingly being applied to simulate atmospheric boundary layer (ABL) flows, especially in wind energy applications; however, the standard functionality provided in commercial CFD models is not suitable for ABL flows. Appropriate CFD modeling in the ABL requires modification of empirically-derived wall function parameters and boundary conditions to avoid erroneous streamwise gradients due to inconsistences between inlet profiles and specified boundary conditions. This work presents a new version of a near-surface wind model for complex terrain called WindNinja. The new version of WindNinja offers two options for flow simulations: 1) the native, fast-running mass-consistent method available in previous model versions and 2) a CFD approach based on the OpenFOAM modeling framework and optimized for ABL flows. The model is described and evaluations of predictions with surface wind data collected from two recent field campaigns in complex terrain are presented. A comparison of predictions from the native mass-consistent method and the new CFD method is also provided.

  3. 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…

  4. 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.

  5. Use of multitemporal information to improve classification performance of TM scenes in complex terrain

    NASA Astrophysics Data System (ADS)

    Conese, Claudio; Maselli, Fabio

    The discrimination of land cover types by means of satellite remotely sensed data is a very challenging task in extremely complex and heterogeneous environments where the surfaces are hardly spectrally identifiable. In these cases the use of multitemporal acquisitions could be expected to enhance substantially classification performance with respect to single scenees, when inserted in procedures which exploit all the information available. The present work discusses this hypothesis and employs three TM scenes of gently undulated terrain in Tuscany (central Italy) from different seasons of one year (February, May and August). The three phenological stages of the vegetated surfaces provided additional statistical information with respect to single scenes. Classification was tested with gaussian maximum likelihood classifiers, both separately on each of the three TM passages and, suitably adapted, on the whole multitemporal set. An iterative process using probabilities estimated from the error matrices of previous single image classifications was also tested. Results of tests show that multitemporal information greatly improves classification performance, particularly when using the statistical procedure described.

  6. Linking aboveground net primary productivity to soil carbon and dissolved organic carbon in complex terrain

    NASA Astrophysics Data System (ADS)

    Peterson, Fox S.; Lajtha, Kate J.

    2013-07-01

    Factors influencing soil organic matter (SOM) stabilization and dissolved organic carbon (DOC) content in complex terrain, where vegetation, climate, and topography vary over the scale of a few meters, are not well understood. We examined the spatial correlations of lidar and geographic information system-derived landscape topography, empirically measured soil characteristics, and current and historical vegetation composition and structure versus SOM fractions and DOC pools and leaching on a small catchment (WS1) in the H.J. Andrews Experimental Forest, located in the western Cascades Range of Oregon, USA. We predicted that aboveground net primary productivity (ANPP), litter fall, and nitrogen mineralization would be positively correlated with SOM, DOC, and carbon (C) content of the soil based on the principle that increased C inputs cause C stores in and losses from in the soil. We expected that in tandem, certain microtopographical and microclimatic characteristics might be associated with elevated C inputs and correspondingly, soil C stores and losses. We confirmed that on this site, positive relationships exist between ANPP, C inputs (litter fall), and losses (exportable DOC), but we did not find that these relationships between ANPP, inputs, and exports were translated to SOM stores (mg C/g soil), C content of the soil (% C/g soil), or DOC pools (determined with salt and water extractions). We suggest that the biogeochemical processes controlling C storage and lability in soil may relate to longer-term variability in aboveground inputs that result from a heterogeneous and evolving forest stand.

  7. 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

  8. Design of a WSN for the sampling of environmental variability in complex terrain.

    PubMed

    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

  9. 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.

  10. 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. PMID:26562341

  11. Using nocturnal cold air drainage flow to monitor ecosystem processes in complex terrain.

    PubMed

    Pypker, Thomas G; Unsworth, Michael H; Mix, Alan C; Rugh, William; Ocheltree, Troy; Alstad, Karrin; Bond, Barbara J

    2007-04-01

    This paper presents initial investigations of a new approach to monitor ecosystem processes in complex terrain on large scales. Metabolic processes in mountainous ecosystems are poorly represented in current ecosystem monitoring campaigns because the methods used for monitoring metabolism at the ecosystem scale (e.g., eddy covariance) require flat study sites. Our goal was to investigate the potential for using nocturnal down-valley winds (cold air drainage) for monitoring ecosystem processes in mountainous terrain from two perspectives: measurements of the isotopic composition of ecosystem-respired CO2 (delta13C(ER)) and estimates of fluxes of CO2 transported in the drainage flow. To test if this approach is plausible, we monitored the wind patterns, CO2 concentrations, and the carbon isotopic composition of the air as it exited the base of a young (approximately 40 yr-old) and an old (>450 yr-old) steeply sided Douglas-fir watershed. Nocturnal cold air drainage within these watersheds was strong, deep, and occurred on more than 80% of summer nights. The depth of cold air drainage rapidly increased to tower height or greater when the net radiation at the top of the tower approached zero. The carbon isotope composition of CO2 in the drainage system holds promise as an indicator of variation in basin-scale physiological processes. Although there was little vertical variation in CO2 concentration at any point in time, we found that the range of CO2 concentration over a single evening was sufficient to estimate delta 13C(ER) from Keeling plot analyses. The seasonal variation in delta 13C(ER) followed expected trends: during the summer dry season delta 13C(ER) became less negative (more enriched in 13C), but once rain returned in the fall, delta 13C(ER) decreased. However, we found no correlation between recent weather (e.g., vapor pressure deficit) and delta 13C(ER) either concurrently or with up to a one-week lag. Preliminary estimates suggest that the nocturnal CO2

  12. Modeling snowpack evolution in complex terrain and forested Central Rockies: A model inter-comparison study

    NASA Astrophysics Data System (ADS)

    Chen, F.; Barlage, M. J.; Tewari, M.; Rasmussen, R.; Bao, Y.; Jin, J.; Lettenmaier, D. P.; Livneh, B.; Lin, C.; Miguez-Macho, G.; Niu, G.; Wen, L.; Yang, Z.

    2011-12-01

    The timing and amount of spring snowmelt runoff in mountainous regions are critical for water resources and managements. Correctly capturing the snow-atmospheric interactions (through albedo and surface energy partitioning) is also important for weather and climate models. This study developed a unique, integrated data set including one-year (2007-2008) snow water equivalent (SWE) observations from 112 SNOTEL sites in the Colorado Headwaters region, 2004-2008 observations (surface heat fluxes, radiation budgets, soil temperature and moisture) from two AmeriFlux sites (Niwot Ridge and GLEES), MODIS snow cover, and river discharge. These observations were used to evaluate the ability of six widely-used land-surface/snow models (Noah, Noah-MP, VIC, CLM, SAST, and LEAF-2) in simulating the seasonal evolution of snowpacks in central Rockies. The overarching goals of this community undertaking are to: 1) understand key processes controlling the evolution of snowpack in this complex terrain and forested region through analyzing field data and various components of snow physics in these models, and 2) improve snowpack modeling in weather and climate models. This comprehensive data set allowed us to address issues that had not been possible in previous snow-model inter-comparison investigations (e.g., SnowMIPs). For instance, models displayed a large disparity in treating radiation and turbulence processes within vegetation canopies. Some models with an overly simplified tree-canopy treatment need to raise snow albedo helped to retain snow on the ground during melting phase. However, comparing modeled radiation and heat fluxes to long-term observations revealed that too-high albedo reduced 75% of solar energy absorbed by the forested surface and resulted in too-low surface sensible heat and longwave radiation returned to the atmosphere, which could be a crucial deficiency for coupled weather and climate models. Large differences were found in simulated SWE by the six LSMs

  13. 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

  14. Weather, Topoclimate, and Phenology: Population Dynamics of Checkerspot Butterflies in Complex Terrain

    NASA Astrophysics Data System (ADS)

    Weiss, S. B.

    2008-12-01

    The pathways leading from climate and weather to the distribution and abundance of organisms need to be clarified as rapid climate change affects ecosystems. This presentation describes population dynamics of the threatened Bay checkerspot butterfly, Euphydryas editha bayensis, in topographically complex habitat and demonstrates how weather and topoclimate drives those dynamics through phenology of butterflies and larval hostplants. We sampled densities of postdiapause larvae at sites in a 100 ha reserve, stratified by Mar 21 potential insolation, to estimate numbers and microdistribution of larvae. Larval numbers ranged from 27,000 to 900,000 over the 24-year study (1985-2008). Four consecutive drought years from 1987 to 1990 led to a 96% decrease in numbers, and sharp declines were observed following warmer than average growing seasons. Changes in larval numbers were negatively correlated to mean growing season temperatures (r2 = 0.36, p < 0.02), and the best stepwise regression model included April temperature, and November and April rainfall (r2 = 0.57, p < 0.001). Changes in the microdistribution of larvae cross the topoclimatic gradient was correlated with change in numbers (r2 = 0.41, p < 0.01) -- when larval numbers increased, the distribution of larvae shifted towards warmer slopes, and when numbers decreased, the distribution shifted toward cooler slopes. Larval densities were least variable on cooler slopes, indicating that cooler slopes provided core habitat and refugia from warm temperatures. The length of the phenological window between peak flight and hostplant senescence predicted population response (r2 = 0.44, p < 0.005). Hostplant senescence patterns across slopes - plants remain green for 4 or more weeks later on cool N-facing slopes than on warm S-facing slopes - explains microdistributional shifts. Many species depend on phenological coincidence with host resources, and occupy complex terrain as well, and these patterns and mechanisms may be

  15. Spatial estimation of daily precipitation in regions with complex relief and scarce data using terrain orientation

    NASA Astrophysics Data System (ADS)

    Castro, Lina Mabel; Gironás, Jorge; Fernández, Bonifacio

    2014-09-01

    Precipitation is the most relevant variable in the hydrological cycle which drives continental hydrologic processes. Its spatial occurrence and behavior are complex and its daily estimation is hard in poorly gauged regions where the topography is highly irregular. Several interpolation methods are available for this purpose, but their performance is quite uncertain. This study develops a spatial interpolation method for daily precipitation that considers both spatial discontinuities and the influence of topography. The method first identifies the precipitation occurrence in each grid-cell as a function of measurements in surrounding rain gauges, and then uses daily elevation vs. precipitation linear regressions throughout the grid-cells where precipitation occurrence is identified. These regressions are classified according to the terrain orientation with respect to the prevailing wind direction. The method was evaluated using categorical statistics that quantify the skill to identify the precipitation occurrence/non-occurrence, and goodness-of-fit statistics to evaluate the error and efficiency. The methodology was compared against inverse distance weighted and simple regression methods, which were implemented considering both continuous and discontinuous precipitation fields. The new method better simulates the occurrence of precipitation, whereas traditional methods applied without considering the spatial discontinuity of precipitation tend to overestimate the frequency of the rainfall events, and thus the magnitude of precipitation at the basin scale. When spatial discontinuity is considered, traditional methods improve their performance and are comparable to the proposed method. Overall, the new method increases the number of days in which elevation vs. precipitation linear regression can be used, thus improving the spatial representation of precipitation in areas with complex relief.

  16. Interactions between grass distribution and land surface form in a semiarid region with complex terrain

    NASA Astrophysics Data System (ADS)

    Bras, R. L.; Flores Cervantes, J. H.

    2008-12-01

    We analyze the spatial distribution of grass biomass and topographic features in two semiarid region in the Southwestern USA. We find that: 1) north-facing terrain has more grass biomass and higher slopes than south-facing terrain; 2) in north-facing hillslopes, grass biomass abundance increases with slope, and in south-facing hillslopes, grass biomass is least abundant at intermediate slopes; 3) grass biomass inversely correlates to solar irradiation that varies as a function of terrain orientation and slope; and 4) biomass distribution is also controlled by the spatial distribution of the channel network. These findings indicate that water availability, as a function of terrain form, controls vegetation growth in the water-limited region, leading to topographically-controlled spatial vegetation patterns that affect terrain form at a local scale. The effects of topography on grass biomass distribution and vice versa are largely dependent on the water fluxes on the surface of the terrain. A model that represents the erosion processes, grass biomass dynamics, and water fluxes in small watersheds is used to elucidate the observations discussed in the previous paragraph.

  17. Enabling high-resolution simulations of atmospheric flow over complex terrain in the WRF model

    NASA Astrophysics Data System (ADS)

    Lundquist, Katherine; Mirocha, Jeff; Wiersema, David; Bao, Jingyi; Daniels, Megan; Chow, Fotini

    2014-11-01

    As model grid resolution increases, atmospheric models are able to represent fine scale terrain, which can result in steep terrain slopes. The standard terrain-following coordinates used by models such as WRF (Weather and Research Forecasting) are unable to handle very steep terrain because of the grid distortion and related numerical errors. This has prompted the development of an alternative gridding technique in the WRF model, known as the immersed boundary method (IBM), which eliminates terrain-following grids and the associated errors (Lundquist et al. 2010,2012). This implementation, WRF-IBM, has been validated for idealized cases and real urban cases with excellent results; however, to date WRF-IBM has been applied with idealized lateral boundary conditions, and uses a no-slip boundary condition. In this work, we detail a multi-year effort to develop WRF-IBM for real, multi-scale simulations, including full atmospheric physics. Results from three aspects of this project are presented: initializing IBM domains using real meteorological and surface data, developing a nest interface between domains using terrain-following and IBM coordinates, and modifying the IBM boundary condition to include a wall model.

  18. 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.

  19. Toward using delta13C of ecosystem respiration to monitor canopy physiology in complex terrain.

    PubMed

    Pypker, T G; Hauck, M; Sulzman, E W; Unsworth, M H; Mix, A C; Kayler, Z; Conklin, D; Kennedy, A M; Barnard, H R; Phillips, C; Bond, B J

    2008-12-01

    In 2005 and 2006, air samples were collected at the base of a Douglas-fir watershed to monitor seasonal changes in the delta13CO2 of ecosystem respiration (delta13C(ER)). The goals of this study were to determine whether variations in delta13C(ER) correlated with environmental variables and could be used to predict expected variations in canopy-average stomatal conductance (Gs). Changes in delta13C(ER) correlated weakly with changes in vapor pressure deficit (VPD) measured 0 and 3-7 days earlier and significantly with soil matric potential (psi(m)) (P value <0.02) measured on the same day. Midday G (s) was estimated using sapflow measurements (heat-dissipation method) at four plots located at different elevations within the watershed. Values of midday Gs from 0 and 3-7 days earlier were correlated with delta13C(ER), with the 5-day lag being significant (P value <0.05). To examine direct relationships between delta13C(ER) and recent Gs, we used models relating isotope discrimination to stomatal conductance and photosynthetic capacity at the leaf level to estimate values of stomatal conductance ("Gs-I") that would be expected if respired CO2 were derived entirely from recent photosynthate. We compared these values with estimates of Gs using direct measurement of transpiration at multiple locations in the watershed. Considering that the approach based on isotopes considers only the effect of photosynthetic discrimination on delta13C(ER), the magnitude and range in the two values were surprisingly similar. We conclude that: (1) delta13C(ER) is sensitive to variations in weather, and (2) delta13C(ER) potentially could be used to directly monitor average, basin-wide variations in Gs in complex terrain if further research improves understanding of how delta13C(ER) is influenced by post-assimilation fractionation processes. PMID:18839214

  20. 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.

  1. 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.

  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. Diurnal patterns in PM 2.5 mass and composition at a background, complex terrain site

    NASA Astrophysics Data System (ADS)

    Tanner, Roger L.; Bairai, Solomon T.; Olszyna, Kenneth J.; Valente, Myra L.; Valente, Ralph J.

    Current fine particle NAAQS specify 24 h integrated mass measurements as the compliance metric. However, the value of continuous short-time resolution sampling (1 h or less) is recognized and being included in US EPA-monitoring strategies. An extensive body of fine mass concentration data has been acquired using continuous PM 2.5 monitoring by TEOM at Look Rock, TN, augmented by trace gas measurements and, during enhanced monitoring periods, continuous sampling for aerosol sulfate (2 methods) and elemental (black) carbon. Continuous data are compared to the 24 h-averaged values of mass and composition from integrated samplers at the site, and for fine mass and sulfate are found to be excellent ( r2=0.97-0.99). We then report the diurnal variations in concentrations from extensive continuous monitoring during 3 summer periods (2000-2002) and for more limited periods throughout calendar year 2001. Levels of the several continuously measured gases and particulate constituents vary in magnitude diurnally according to expected patterns based on their emissions, their formation and loss processes, their lifetimes toward wet and dry deposition, the dynamics of up-slope—down-slope circulation, and solar-driven boundary layer growth and decay. Thus, concentrations of short-lifetime gases have minima at sunrise and maxima in the evening. Long-lived primary species (CO and black carbon) increase in mid-morning as the boundary layer height reaches the site and decay thereafter. Long-lived secondary species (sulfate and fine mass) show little diurnal variability. Factors controlling the observed diurnal variability thus significantly influence the extent and timing of human exposure to pollutant species, as well as affecting visibility impairment in complex terrain environments near the Great Smoky Mountains National Park.

  4. 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

  5. Improving Radar QPE's in Complex Terrain for Improved Flash Flood Monitoring and Prediction

    NASA Astrophysics Data System (ADS)

    Cifelli, R.; Streubel, D. P.; Reynolds, D.

    2010-12-01

    Quantitative Precipitation Estimation (QPE) is extremely challenging in regions of complex terrain due to a combination of issues related to sampling. In particular, radar beams are often blocked or scan above the liquid precipitation zone while rain gauge density is often too low to properly characterize the spatial distribution of precipitation. Due to poor radar coverage, rain gauge networks are used by the National Weather Service (NWS) River Forecast Centers as the principal source for QPE across the western U.S. The California Nevada River Forecast Center (CNRFC) uses point rainfall measurements and historical rainfall runoff relationships to derive river stage forecasts. The point measurements are interpolated to a 4 km grid using Parameter-elevation Regressions on Independent Slopes Model (PRISM) data to develop a gridded 6-hour QPE product (hereafter referred to as RFC QPE). Local forecast offices can utilize the Multi-sensor Precipitation Estimator (MPE) software to improve local QPE’s and thus local flash flood monitoring and prediction. MPE uses radar and rain gauge data to develop a combined QPE product at 1-hour intervals. The rain gauge information is used to bias correct the radar precipitation estimates so that, in situations where the rain gauge density and radar coverage are adequate, MPE can take advantage of the spatial coverage of the radar and the “ground truth” of the rain gauges to provide an accurate QPE. The MPE 1-hour QPE analysis should provide better spatial and temporal resolution for short duration hydrologic events as compared to 6-hour analyses. These hourly QPEs are then used to correct radar derived rain rates used by the Flash Flood Monitoring and Prediction (FFMP) software in forecast offices for issuance of flash flood warnings. Although widely used by forecasters across the eastern U.S., MPE is not used extensively by the NWS in the west. Part of the reason for the lack of use of MPE across the west is that there has

  6. 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

  7. A Model-Data Integration Framework for Interpreting Eddy Covariance Flux Measurements on Complex Terrain Covered by a Tall Canopy

    NASA Astrophysics Data System (ADS)

    Banerjee, T.; Novick, K. A.; Katul, G. G.; Land Atmosphere Interaction Group-(Katul Group)

    2011-12-01

    The Eddy Covariance (EC) technique has been extensively used to determine turbulent fluxes above plant canopies, yet linking EC fluxes to ecosystem scalar sources and sinks remains an active research topic. Over complex terrain, advective fluxes become large thereby disturbing the constant turbulent flux assumption. Because the genesis of these advective terms is the interaction between the pressure field and topography, a framework that links the modes of topographic variability to scalar flux gradients above the canopy is required to further progress on this topic. Here, a new EC flux tower in the mountainous terrain of the Coweeta Hydrologic Laboratory is used to test a novel approach for quantifying the magnitude of horizontal and vertical advective fluxes within the tower footprint. The approach is based on a two dimensional numerical model for wind flow over complex terrain covered by a tall canopy. Model runs are compared to vertical flux gradients and mean concentration profiles of CO2, H2O, air temperature, and mean velocity measured at the tower. These model runs are then used to explore what modes of variability in topography impact the generation of flux gradients above the canopy and how these modes may shift due to thermal stratification.

  8. Impact of Different Topographic Corrections on Prediction Accuracy of Foliage Projective Cover (fpc) in a Topographically Complex Terrain

    NASA Astrophysics Data System (ADS)

    Ediriweera, S.; Pathirana, S.; Danaher, T.; Nichols, D.; Moffiet, T.

    2012-07-01

    Quantitative retrieval of land surface biological parameters (e.g. foliage projective cover [FPC] and Leaf Area Index) is crucial for forest management, ecosystem modelling, and global change monitoring applications. Currently, remote sensing is a widely adopted method for rapid estimation of surface biological parameters in a landscape scale. Topographic correction is a necessary pre-processing step in the remote sensing application for topographically complex terrain. Selection of a suitable topographic correction method on remotely sensed spectral information is still an unresolved problem. The purpose of this study is to assess the impact of topographic corrections on the prediction of FPC in hilly terrain using an established regression model. Five established topographic corrections [C, Minnaert, SCS, SCS+C and processing scheme for standardised surface reflectance (PSSSR)] were evaluated on Landsat TM5 acquired under low and high sun angles in closed canopied subtropical rainforest and eucalyptus dominated open canopied forest, north-eastern Australia. The effectiveness of methods at normalizing topographic influence, preserving biophysical spectral information, and internal data variability were assessed by statistical analysis and by comparing field collected FPC data. The results of statistical analyses show that SCS+C and PSSSR perform significantly better than other corrections, which were on less overcorrected areas of faintly illuminated slopes. However, the best relationship between FPC and Landsat spectral responses was obtained with the PSSSR by producing the least residual error. The SCS correction method was poor for correction of topographic effect in predicting FPC in topographically complex terrain.

  9. 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...

  10. 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.

  11. 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

  12. 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.

  13. Variability of Sub-Canopy Flow, Temperature, and Horizontal Advection in Moderately Complex Terrain

    NASA Astrophysics Data System (ADS)

    Thomas, Christoph K.

    2011-04-01

    We examine the space-time structure of the wind and temperature fields, as well as that of the resulting spatial temperature gradients and horizontal advection of sensible heat, in the sub-canopy of a forest with a dense overstorey in moderately complex terrain. Data were collected from a sensor network consisting of ten stations and subject to orthogonal decomposition using the multiresolution basis set and stochastic analyses including two-point correlations, dimensional structure functions, and various other bulk measures for space and time variability. Despite some similarities, fundamental differences were found in the space-time structure of the motions dominating the variability of the sub-canopy wind and temperature fields. The dominating motions occupy similar spatial, but different temporal, scales. A conceptual space-time diagram was constructed based on the stochastic analysis that includes the important end members of the spatial and temporal scales of the observed motions of both variables. Short-lived and small-scale motions govern the variability of the wind, while the diurnal temperature oscillation driven by the surface radiative transfer is the main determinant of the variability in the temperature signal, which occupies much larger time scales. This scale mismatch renders Taylor's hypothesis for sub-canopy flow invalid and aggravates the computation of meaningful estimates of horizontal advective fluxes without dense spatial information. It may further explain the ambiguous and inconclusive results reported in numerous energy and mass balance and advection studies evaluating the hypothesis that accounting for budget components other than the change in storage term and the vertical turbulent flux improves the budget closure when turbulent diffusion is suppressed in plant canopies. Estimates of spatial temperature gradients and advective fluxes were sensitive to the network geometry and the spatial interpolation method. The assumption of linear

  14. 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. PMID:22168106

  15. Flux-Variance Similarity in Complex Terrain and Its Sensitivity to Different Methods of Treating Non-stationarity

    NASA Astrophysics Data System (ADS)

    Babić, Nevio; Večenaj, Željko; De Wekker, Stephan F. J.

    2016-04-01

    Various criteria have been developed to remove non-stationarity in turbulence time series, though it remains unclear how the choice of the stationarity criterion affects similarity functions in the framework of the Monin-Obukhov similarity theory. To investigate this, we use stationary datasets that result from applying five common criteria to remove non-stationarity in turbulence time series from the Terrain-Induced Rotor EXperiment conducted in Owens Valley, California. We determine the form of the flux-variance similarity functions and the scatter around these similarity functions for all five stationary datasets. Data were collected at two valley locations and one slope location using 34-m flux towers with six levels of turbulence measurements. Our results show (i) systematic differences from previously found near-neutral values of the parameters in the flux-variance similarity functions over flat terrain, indicating a larger anisotropy of the flow over complex than over flat terrain, (ii) a reduction of this anisotropy when stationary data are used, with the amount of reduction depending on the stationarity criterion, (iii) a general reduction in scatter around the similarity functions when using stationary data but more so for stable than for unstable stratification, and for valley locations than for the slope location, and (iv) a weak variation with height of near-neutral values of parameters in the flux-variance similarity functions.

  16. 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

  17. 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

  18. 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.

  19. 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

  20. Satellite-based solar radiation mapping over complex terrain: Validation in the Alps and possible improvements

    NASA Astrophysics Data System (ADS)

    Castelli, Mariapina; Stoeckli, Reto; Tetzlaff, Anke; Ernst Wagner, Jochen; Zardi, Dino; Petitta, Marcello

    2013-04-01

    . Consequently it is recommended to include in the clear-sky model more accurate input than the currently used monthly climatologies of aerosol and the operational 1 day forecast of column water vapor amount from the ECMWF model ouptut. References [1] K. V. Khlopenkov And A. P. Trishchenko, "SPARC: New Cloud, Snow, and Cloud Shadow Detection Scheme for Historical 1-km AVHHR Data over Canada", Journal of Atmospheric and Oceanic Technology, 24, pp. 322-343, 2007. [2] R.W. Müller, C. Matsoukas, A. Gratzki, H.D. Behr, R. Hollmann. "The CM-SAF operational scheme for the satellite based retrieval of solar surface irradiance - A LUT based eigenvector hybrid approach", Remote Sensing of Environment, 113, pp.1012-1024, 2009. [3] R. Stöckli (in prep.). "Supplementing Heliosat for physically-based surface radiation retrieval in complex terrain."

  1. High-resolution simulations of atmospheric CO2 over complex terrain - representing the Ochsenkopf mountain tall tower

    NASA Astrophysics Data System (ADS)

    Pillai, D.; Gerbig, C.; Ahmadov, R.; Rödenbeck, C.; Kretschmer, R.; Koch, T.; Thompson, R.; Neininger, B.; Lavrié, J. V.

    2011-08-01

    Accurate simulation of the spatial and temporal variability of tracer mixing ratios over complex terrain is challenging, but essential in order to utilize measurements made in complex orography (e.g. mountain and coastal sites) in an atmospheric inverse framework to better estimate regional fluxes of these trace gases. This study investigates the ability of high-resolution modeling tools to simulate meteorological and CO2 fields around Ochsenkopf tall tower, situated in Fichtelgebirge mountain range- Germany (1022 m a.s.l.; 50°1'48" N, 11°48'30" E). We used tower measurements made at different heights for different seasons together with the measurements from an aircraft campaign. Two tracer transport models - WRF (Eulerian based) and STILT (Lagrangian based), both with a 2 km horizontal resolution - are used together with the satellite-based biospheric model VPRM to simulate the distribution of atmospheric CO2 concentration over Ochsenkopf. The results suggest that the high-resolution models can capture diurnal, seasonal and synoptic variability of observed mixing ratios much better than coarse global models. The effects of mesoscale transports such as mountain-valley circulations and mountain-wave activities on atmospheric CO2 distributions are reproduced remarkably well in the high-resolution models. With this study, we emphasize the potential of using high-resolution models in the context of inverse modeling frameworks to utilize measurements provided from mountain or complex terrain sites.

  2. High-resolution simulations of atmospheric CO2 over complex terrain - representing the Ochsenkopf mountain tall tower

    NASA Astrophysics Data System (ADS)

    Pillai, D.; Gerbig, C.; Ahmadov, R.; Rödenbeck, C.; Kretschmer, R.; Koch, T.; Thompson, R.; Neininger, B.; Lavrič, J. V.

    2011-03-01

    Accurate simulation of the spatial and temporal variability of tracer mixing ratios over complex terrain is challenging, but essential in order to utilize measurements made in complex orography (e.g. mountain and coastal sites) in an atmospheric inverse framework to better estimate regional fluxes of these trace gases. This study investigates the ability of high-resolution modeling tools to simulate meteorological and CO2 fields around Ochsenkopf tall tower, situated in Fichtelgebirge mountain range - Germany (1022 m a.s.l.; 50°1'48'' N, 11°48'30'' E). We used tower measurements made at different heights for different seasons together with the measurements from an aircraft campaign. Two tracer transport models - WRF (Eulerian based) and STILT (Lagrangian based), both with a 2 km horizontal resolution - are used together with the satellite-based biospheric model VPRM to simulate the distribution of atmospheric CO2 concentration over Ochsenkopf. The results suggest that the high-resolution models can capture diurnal, seasonal and synoptic variability of observed mixing ratios much better than coarse global models. The effects of mesoscale transports such as mountain-valley circulations and mountain-wave activities on atmospheric CO2 distributions are reproduced remarkably well in the high-resolution models. With this study, we emphasize the potential of using high-resolution models in the context of inverse modeling frameworks to utilize measurements provided from mountain or complex terrain sites.

  3. 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.

  4. Very High Resolution Numerical Weather Prediction of Wind Shear Event in the Complex Terrain Around Juneau Alaska

    NASA Astrophysics Data System (ADS)

    Morton, D.; Arnold, D.; Schicker, I.; Dierking, C.; Harrison, K.

    2011-12-01

    Juneau International Airport is surrounded by complex terrain, often presenting challenging conditions to departing aircraft. General aviation departure procedures for Runway 08 include a 180-degree right turn "as soon as practical" in order to avoid steeply rising terrain. Under strong wind conditions characterized by post-frontal topographically enhanced wind shear, aircraft following these procedures may encounter turbulence or wind shear classified as severe. In January 1993, a Boeing 727 aircraft at a 30-degree bank encountered extreme crosswinds resulting in departure from controlled flight, with successful recovery occurring within only 50 meters of the ground. In this work, we focus on a similar event at Juneau from December 2009. This case has been modeled with WRF at very high resolutions down to 111 m horizontal, with mixed results. The focus of this work is to investigate in more detail the problems, costs and benefits of using very high resolution topography and model runs in a high-wind event in complex terrain. Several model runs will be performed, and results will be compared with each other and station observations available through the Juneau Airport Wind System (JAWS). Two high resolution topographies - the USGS National Elevation Dataset (NED) and the Shuttle Radar Topography Mission (SRTM) - will be compared with the USGS 30s topography in their ability to match the real topography and their influence on forecast winds. Additionally, an attempt will be made to push the model into the realm of Large Eddy Simulation (LES) with a 50 m horizontal resolution in a limited region.

  5. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    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.

  7. 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``.

  8. 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.

  9. 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…

  10. 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.

  11. Lagrangian stochastic modeling of pollutant dispersion in the turbulent atmospheric boundary layer - application to an urban area over complex terrain

    NASA Astrophysics Data System (ADS)

    Fattal, Eyal; Gavze, Ehud

    2014-05-01

    The modeling of pollutant dispersion in the atmospheric boundary layer depends on an adequate description of the turbulent processes. Since turbulence is a multi-scale phenomenon characterized by a high degree of disorder, a statistical approach is needed. Among the statistical approaches, Lagrangian stochastic particle models provide a well established theoretical framework for the description of pollutant dispersion in different atmospheric boundary layer scenarios. Usually turbulent structure in the surface layer is described in terms of Monin-Obukhov similarity theory (MOST) using universal relationships between scaling parameters. These relationships have been shown to be valid in the case of horizontal homogeneity for stationary turbulence. The description of the turbulent processes above rough surfaces, such as over canopies, is a more complex case. For the urban canopy it was found that under developed stationary turbulence conditions MOST relations are approximately valid (in some cases, with extensions). An even more complex case is that of rough surfaces over topography, as no similarity theory has been established to properly describe the turbulence exchange over heterogeneous surfaces in complex terrain. We show Lagrangian stochastic model simulations based on MOST against measurements in urban canopy over complex terrain. Comparison gives good agreement with direct tracer measurements, in cases of neutral and convective stratifications. It is shown that in conditions of developed stationary turbulence, at most areas, there is in an agreement with MOST predictions. However, in very low wind conditions the turbulent nocturnal boundary layer is not necessarily stationary and is spatially non-homogeneous. This results in larger horizontal velocity standard deviation than expected in regular stable regime, as manifested in the pollutant pattern.

  12. 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

    2015-01-01

    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

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. Average diurnal behavior of surface winds during summer at sites in complex terrain

    SciTech Connect

    Garrett, A.J.; Smith, F.G. III

    1985-02-01

    Mean diurnal wind distributions from five surface stations in the rugged Geysers area of northern California were examined to determine how they were affected by the terrain. The one-dimensional slop-flow model of Garrett was abel to simulate the average diurnal wind distribution at the station with the simplest slope geometry and using only routine weather observations as input. Wind direction frequency distributions at the other four stations clearly could not be explained by a simple daytime upslope and nighttime downslope wind distribution. Winds blew perpendicular to canyon axes (simple katabatic and daytime upslope flow) or parallel to canyon axes (organized drainage and upvalley winds), depending on station location. Winds always blew upslope during the day, but at two stations the wind blen some night and downslope on the others. The upslope flow at night may have been caused by prevailing winds in one case, and by drainage winds flowing off an opposing slope and across the intervening riverbed in the other.

  18. Application of a mesoscale model with 4DDA to the complex terrain near Tooele, Utah

    SciTech Connect

    Cosdtigan, K.R.; Flicker, D.G.; Lee, J.T.

    1995-05-01

    The Tooele Army Depot South Area is located in the high, broad Rush Valley of North-Central Utah. The valley is approximately 1560 m above sea level and roughly 20 Ion across from East to West and 45 km long from North to South. It is surrounded on three sides by mountain ranges with the Oquirrh Mountains to the East, the Stansbury and Onaqui Mountains to the West, and the Sheep Rock and East Tintic Mountains to the South. These mountain ranges include peaks from about 2400 m to 3350 m MSL. A somewhat shorter barrier (2000 m South Mountain) exists on the North end of the valley and the lowest passes are on the north and east sides. Further to the North lies Tooele Valley and the Great Salt Lake. Another significant lake is in the adjacent valley to the east of Rush Valley and the small Rush Lake is at the North end of Rush Valley. The combination of the topography and the lakes leads to interesting local meteorology affected by slope and valley flows and lake breezes for Atmospheric Circulations) for operational use in this area. The nudging scheme takes advantage of an extensive network of local observations in the valley. At the depot there are seven surface observing stations and a 30 m tower, which collect wind, temperature, and humidity data, and Tooele County has recently installed a network of about 25 additional surface stations throughout Rush and Tooele Valleys and on some of the surrounding higher terrain.

  19. Spatial distribution of hydrogen sulfide from two geothermal power plants in complex terrain

    NASA Astrophysics Data System (ADS)

    Olafsdottir, S.; Gardarsson, S. M.; Andradottir, H. O.

    2014-01-01

    Concerns have arisen about the health impact and odor annoyance of hydrogen sulfide (H2S) emissions associated with geothermal power production. Measurements have been made at stationary measuring stations in inhabited areas but little is known about the spatial behavior of the H2S plumes. This study presents field measurements of the spatial distribution of the ground concentration of H2S within a 30 km radius of two geothermal power plants during 20 distinct events spanning one year. The results showed that high H2S concentration was correlated with high air stability, low wind speed and absence of precipitation. The odor threshold (11 μg m-3) was exceeded in all events. The instantaneous measurements exceeded the 24-h average national health limit (50 μg m-3) up to 26 km from the power plants. The shape of the measured plumes at the same location was similar between events, indicating repeated patterns in plume distribution. Convergence of plumes was observed due to spatial variability in wind direction. Plumes were found to follow mountain passes and accumulate alongside a mountain range. AERMOD modeling demonstrated that narrower plumes with higher concentration can be expected for smoother terrain, such as lakes, consistent with measurements.

  20. 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.

  1. 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.

  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. In situ monitoring and machine modeling of snowpack evolution in complex terrains

    NASA Astrophysics Data System (ADS)

    Frolik, J.; Skalka, C.

    2014-12-01

    It is well known that snowpack evolution depends on variety of landscape conditions including tree cover, slope, wind exposure, etc. In this presentation we report on methods that combine modern in-situ sensor technologies with machine learning-based algorithms to obtain improved models of snowpack evolution. Snowcloud is an embedded data collection system for snow hydrology field research campaigns that leverages distributed wireless sensor network technology to provide data at low cost and high spatial-temporal resolution. The system is compact thus allowing it to be deployed readily within dense canopies and/or steep slopes. The system has demonstrated robustness for multiple-seasons of operation thus showing it is applicable to not only short-term strategic monitoring but extended studies as well. We have used data collected by Snowcloud deployments to develop improved models of snowpack evolution using genetic programming (GP). Such models can be used to augment existing sensor infrastructure to obtain better areal snow depth and snow-water equivalence estimations. The presented work will discuss three multi-season deployments and present data (collected at 1-3 hour intervals and a multiple locations) on snowdepth variation throughout the season. The three deployment sites (Eastern Sierra Mountains, CA; Hubbard Brook Experimental Forest, NH; and Sulitjelma, Norway) are varied not only geographically but also terrain-wise within each small study area (~2.5 hectacre). We will also discuss models generated by inductive (GP) learning, including non-linear regression techniques and evaluation, and how short-term Snowcloud field campaigns can augment existing infrastructure.

  4. 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

  5. Vertical distribution of atmospheric constituents above complex terrain - Influence of a mesoscale system

    NASA Astrophysics Data System (ADS)

    Berkes, Florian; Hoor, Peter; Bozem, Heiko; Meixner, Franz; Weigel, Ralf; Sprenger, Michael; Lelieveld, Jos

    2014-05-01

    Measurements in and above the planetary boundary layer (PBL) are essential to fully understand the exchange and transport processes between the PBL and the free troposphere (FT). Here we discuss the impact of a mesoscale system on the local trace gas and particle distribution above the PBL over hilly terrain. During the field campaign PARADE (PArticles and RAdicals: Diel observations of the impact of urban and biogenic Emissions) in August and September 2011 measurements were conducted at the Taunus Observatory on Mount "Kleiner Feldberg (KF)" (825 m asl.), about 20 km northwest of Frankfurt am Main in Germany. For the vertical composition of the lowest 3000 m, high-resolution measurements were performed using 174 radio soundings. The measurements are complemented by continuous boundary layer observations of a ceilometer and a variety of reactive tracers (CO, NOx, O3, VOCs) on the mountain top. In addition, aircraft measurements of CO2, CO, O3, temperature, humidity and aerosol number concentration and size distribution were performed during the first week of September. The PBL height varied during the measurement campaign between 1 and 2.5 km. The variations are due to very changeable weather, synoptic fronts as well as local phenomena such as low clouds and fog. The analysis of the data from different instruments shows good agreement in determining the boundary layer height under windless high pressure conditions, as well as with certain restrictions on cloudy and windy days. Based on the PBL investigation, the aircraft-based trace gas measurements were used to identify transport and exchange processes between the free atmosphere and the boundary layer, additionally supported with high-resolution backward-trajectories initialized every 10 seconds along the flight track, based on the wind fields from the COSMO-EU model. On 2 September 2011 we observed an enhanced particle number concentration and low ozone in the free troposphere at two flights around KF. Local

  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. The Temperature Gradient and Transition Timescales as a Function of Topography in Complex Terrain

    NASA Astrophysics Data System (ADS)

    Higgins, C. W.; Hoch, S. W.; Pardyjak, E.

    2013-12-01

    Large portions of the Earth's surface are covered by mountainous areas, and understanding atmospheric flow over these regions is critical for weather prediction, (micro)climatological research, and dispersion modeling. Complex interactions between the topographic features, the synoptic forcing and the buoyant forcing drive flow patterns and flow regime transitions. As a part of the MATTERHORN field experiment, Distributed Temperature Sensing (DTS) technology was used to measure the vertical temperature gradient on an east facing slope across a 2km transect of granite ridge in the Utah west desert, from the base of the mountain to the middle slope. Thus, the temperature gradient is sampled above a wide range of topographic features, from valley formations to ridges, and over a wide range of slope and aspect angles. The relationship between these landforms and the timescales of morning and evening transitions is explored and presented.

  10. The importance of model resolution for predicting precipitation and runoff in complex terrain

    SciTech Connect

    Costigan, K.R.; Bossert, J.E.; Breshears, D.D.; Campbell, K.; Martens, S.N.

    1998-12-01

    As the demand for limited stores of fresh water grows, optimum use of water resources becomes paramount, especially in arid and semi-arid regions of the world. In order to make the best use of these limited resources, it is important to understand the entire hydrologic cycle in these regions and to be able to explore the potential effects of increased use and of changes in the regional climate. As part of Los Alamos' coupled environmental modeling initiative, the authors are linking a suite of environmental models to simulate the hydrologic cycle within river basins. Their goal is to produce a fully interactive coupling of atmospheric, surface hydrology, river, and groundwater models to allow feedbacks throughout the system. This paper focuses on the interaction between the atmospheric and surface hydrology models. The role of the complex topography in determining the spatial distribution of winter precipitation is investigated through sensitivity tests carried out using different horizontal resolutions in the modeling system.

  11. 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.

  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 PAGESBeta

    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. Adaptive Airborne Doppler Wind Lidar Beam Scanning Patterns for Complex Terrain and Small Scale Organized Atmospheric Structure Observations

    NASA Astrophysics Data System (ADS)

    Emmitt, G.; O'Handley, C.; de Wekker, S. F.

    2008-12-01

    The conical scan is the traditional pattern used to obtain vertical profiles of the wind field with an airborne Doppler wind lidar. Nadir or zenith pointing scanning wedges are ideal for this type of scan. A bi-axis scanner has been operated on a Navy Twin Otter for more than 6 years and has been recently installed on a Navy P3 for use in a field experiment to study typhoons. The bi-axis scanner enables a broad range of scanning patterns. A subset of the possible patterns is critical to obtaining useful wind profiles in the presence of complex terrain or small (~ 100's of meters) organized atmospheric structures (rolls, updrafts, waves, etc). Several scanning strategies have been tested in flights over the Monterey Peninsula and within tropical cyclones. Combined with Google Earth (on-board) and satellite imagery overlays, new realtime adaptive scanning algorithms are being developed and tested. The results of these tests (both real and simulated) will be presented in the form of case studies.

  15. Assessing regression kriging for its ability to represent precipitation fields over complex terrain using different gauging network densities.

    NASA Astrophysics Data System (ADS)

    Tsanis, Ioannis; Grillakis, Manolis; Varouchakis, Emmanouil; Koutroulis, Aristeidis; Seiradakis, Kostantinos

    2015-04-01

    Distributed hydrological modeling require spatially continuous precipitation data of high quality. However, precipitation is usually measured locally at a limited number of stations. Especially in areas of complex terrain, where the topography plays key role in the precipitation process, the gauging network is usually sparse or malfunction. The need of reliable precipitation data has led to the development of various spatial interpolation techniques specially designed for precipitation. Methodologies that can combine precipitation data to secondary information have been developed improving the skill of the interpolation. Regression kriging is an interpolation methodology which uses variable point values by combining a regression approach with a geostatistical approach (i.e. measuring spatial autocorrelation by kriging). The methodology is simple to use and has been already implemented in R and ArcGIS environments, thus it has a wider board of potential users. The methodology is assessed for its ability to represent precipitation fields in various precipitation station densities. Moreover, the results of Regression Kriging interpolation are compared to other interpolation techniques such as IDW, Kriging, Natural neighbor and spline, implemented in ArcGIS toolbox.

  16. 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

  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. 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.

  20. Comparing model-based predictions of a wind turbine wake to LiDAR measurements in complex terrain

    NASA Astrophysics Data System (ADS)

    Kay, Andrew; Jones, Paddy; Boyce, Dean; Bowman, Neil

    2013-04-01

    The application of remote sensing techniques to the measurement of wind characteristics offers great potential to accurately predict the atmospheric boundary layer flow (ABL) and its interactions with wind turbines. An understanding of these interactions is important for optimizing turbine siting in wind farms and improving the power performance and lifetime of individual machines. In particular, Doppler wind Light Detection and Ranging (LiDAR) can be used to remotely measure the wind characteristics (speed, direction and turbulence intensity) approaching a rotor. This information can be utilised to improve turbine lifetime (advanced detection of incoming wind shear, wind veer and extreme wind conditions, such as gusts) and optimise power production (improved yaw, pitch and speed control). LiDAR can also make detailed measurements of the disturbed wind profile in the wake, which can damage surrounding turbines and reduce efficiency. These observational techniques can help engineers better understand and model wakes to optimize turbine spacing in large wind farms, improving efficiency and reducing the cost of energy. NEL is currently undertaking research to measure the disturbed wind profile in the wake of a 950 kW wind turbine using a ZephIR Dual Mode LiDAR at its Myres Hill wind turbine test site located near Glasgow, Scotland. Myres Hill is moderately complex terrain comprising deep peat, low lying grass and heathers, localised slopes and nearby forest, approximately 2 km away. Measurements have been obtained by vertically scanning at 10 recorded heights across and above the rotor plane to determine the wind speed, wind direction and turbulence intensity profiles. Measurement stations located at various rotor diameters downstream of the turbine were selected in an attempt to capture the development of the wake and its recovery towards free stream conditions. Results of the measurement campaign will also highlight how the wake behaves as a result of sudden gusts

  1. Dynamically downscaling wind storms over complex terrain with WRF: establishing the model performance and associated uncertainties

    NASA Astrophysics Data System (ADS)

    José Gómez-Navarro, Juan; Raible, Christoph C.

    2015-04-01

    This study aims at identifying a setup of the Weather Research and Forecasting (WRF) model that minimises systematic errors in hindcast simulations focused on the simulation of surface wind over complex topography. The existence of many options to configure this kind of simulation, e.g. the choice of PBL scheme, the nesting techniques or the number of vertical levels, leads to an important level of uncertainty that needs to be addressed prior the use of the downscaled product. The sensitivity of the model performance to these factors is assessed in this study. To accomplish this evaluation, a number of sensitivity simulations reaching a spatial resolution of 2 km are carried out and compared to an observational dataset. Given the importance of wind storms, the analysis is based on case studies selected from 24 historical wind storms that caused great economic damage in Switzerland. These situations are downscaled using a total of 9 different model setups, but sharing the same driving data set: Era Interim. The PBL schemes evaluated are selected with the aim of spanning a great part of the uncertainty space. The results show that the unresolved topography leads to a general overestimation of wind speed in WRF. However, this error can be substantially ameliorated by a suitable choice of the PBL scheme, which also yields an improvement of the spatial structure of wind speed. Wind direction, although generally well reproduced by the simulation, is not very sensitive to this choice and presents systematic errors that can not be reduced with a suitable model configuration. Further sensitivity tests are carried out aiming at identifying the role of three types of nesting: not nudging at all, re-forecast runs, analysis nudging and spectral nudging. Results indicate that restricting the freedom of the model to develop large-scale disturbances generally increases the temporal agreement with respect to the observations, although none of such techniques outperforms the others

  2. 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

  3. 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. PMID:23673194

  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. Modeling SF{sub 6} plume dispersion in complex terrain and meteorology with a limited data set

    SciTech Connect

    Schalk, W.W. III

    1996-10-01

    Early actions of emergency responders during hazardous material releases are intended to assess contamination and potential public exposure. As measurements are collected, an integration of model calculations and measurements can assist to better understand the situation. This study applied a high resolution version of the operational 3-D numerical models used by Lawrence Livermore National Laboratory to a limited meteorological and tracer data set to assist in the interpretation of the dispersion pattern on a 140 km scale. The data set was collected from a tracer release during the morning surface inversion and transition period in the complex terrain of the Snake River Plain near Idaho Falls, Idaho in November 1993 by the United States Air Force. Sensitivity studies were conducted to determine model input parameters that best represented the study environment. These studies showed that mixing and boundary layer heights, atmospheric stability, and rawinsonde data are the most important model input parameters affecting wind field generation and tracer dispersion. Numerical models and limited measurement data were used to interpret dispersion patterns through the use of data analysis, model input determination, and sensitivity studies. Comparison of the best-estimate calculation to measurement data showed that model results compared well with the aircraft data, but had moderate success with the few surface measurements taken. The moderate success of the surface measurement comparison, may be due to limited downward mixing of the tracer as a result of the model resolution determined by the domain size selected to study the overall plume dispersion. 8 refs., 40 figs., 7 tabs.

  6. Recycling of suspended particulates by the interaction of sea-land breeze circulation and complex coastal terrain

    NASA Astrophysics Data System (ADS)

    Choi, H.; Zhang, Y. H.; Takahashi, S.

    2004-09-01

    The dispersion of recycled particulates in the complex coastal terrain surrounding Kangnung city, Korea was investigated using a three-dimensional non-hydrostatic numerical model and lagrangian particle model (or random walk model). The results show that particulates at the surface of the city that float to the top of thermal internal boundary layer (TIBL) are then transported along the eastern slope of the mountains with the sea breeze passage and nearly reach the top of the mountains. Those particulates then disperse eastward at this upper level over the coastal sea and finally spread out over the open sea. Total suspended particulate (TSP) concentration near the surface of Kangnung city is very low. At night, synoptic scale westerly winds intensify due to the combined effect of the synoptic scale wind and land breeze descending the eastern slope of the mountains toward the coast and further seaward. This increase in speed causes development of internal gravity waves and a hydraulic jump up to a height of about 1 km above the surface over the city. Particulate matter near the top of the mountains also descends the eastern slope of the mountains during the day, reaching the central city area and merges near the surface inside the nocturnal surface inversion layer (NSIL) with a maximum ground level concentration of TSP occurring at 0300 LST. Some particulates are dispersed following the propagation area of internal gravity waves and others in the NSIL are transported eastward to the coastal sea surface, aided by the land breeze. The following morning, particulates dispersed over the coastal sea from the previous night, tend to return to the coastal city of Kangnung with the sea breeze, developing a recycling process and combine with emitted surface particulates during the morning. These processes result in much higher TSP concentration. In the late morning, those particulates float to the top of the TIBL by the intrusion of the sea breeze and the ground level TSP

  7. 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.

  8. 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.

    2015-03-01

    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. 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 really new and very promising method of improving the profile retrieval in a mountain region is adding further information in the retrieval, such as the surface temperature at fixed levels along a topographic slope or from nearby mountain tops.

  9. 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

  10. 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.

  11. Terrain Simulation

    NASA Technical Reports Server (NTRS)

    1992-01-01

    A highlight of the IMAX film, Blue Planet, is a 100-second computer- generated animation of a flight and earthquake simulation along California's San Andreas Fault. Created by the VESA group at the Jet Propulsion Laboratory, the sequence required the development of a technique to make possible terrain rendering of very large digital images. An image mosaic of California constructed from Landsat data made this possible. An advanced pyramidal terrain rendering technique was developed, significantly reducing the necessary time involved in transferring the Landsat data to film. The new technique has also enabled NASA to develop new perspective rendering technologies in order to cope with anticipated increased remote sensor data.

  12. Sensitivity of the WRF model to PBL parametrisations and nesting techniques: evaluation of wind storms over complex terrain

    NASA Astrophysics Data System (ADS)

    Gómez-Navarro, J. J.; Raible, C. C.; Dierer, S.

    2015-10-01

    Simulating surface wind over complex terrain is a challenge in regional climate modelling. Therefore, this study aims at identifying a set-up of the Weather Research and Forecasting Model (WRF) model that minimises systematic errors of surface winds in hindcast simulations. Major factors of the model configuration are tested to find a suitable set-up: the horizontal resolution, the planetary boundary layer (PBL) parameterisation scheme and the way the WRF is nested to the driving data set. Hence, a number of sensitivity simulations at a spatial resolution of 2 km are carried out and compared to observations. Given the importance of wind storms, the analysis is based on case studies of 24 historical wind storms that caused great economic damage in Switzerland. Each of these events is downscaled using eight different model set-ups, but sharing the same driving data set. The results show that the lack of representation of the unresolved topography leads to a general overestimation of wind speed in WRF. However, this bias can be substantially reduced by using a PBL scheme that explicitly considers the effects of non-resolved topography, which also improves the spatial structure of wind speed over Switzerland. The wind direction, although generally well reproduced, is not very sensitive to the PBL scheme. Further sensitivity tests include four types of nesting methods: nesting only at the boundaries of the outermost domain, analysis nudging, spectral nudging, and the so-called re-forecast method, where the simulation is frequently restarted. These simulations show that restricting the freedom of the model to develop large-scale disturbances slightly increases the temporal agreement with the observations, at the same time that it further reduces the overestimation of wind speed, especially for maximum wind peaks. The model performance is also evaluated in the outermost domains, where the resolution is coarser. The results demonstrate the important role of horizontal

  13. 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.

  14. Simulation of Atmospheric Pollution Dispersion over Complex Terrain Region of Jharkhand with FLEXPART-WRF with incorporation of improved Turbulence Intensity relationships

    NASA Astrophysics Data System (ADS)

    Madala, Srikanth; Satyanarayana A. N., V.; Srinivas C., V.; Boadh, Rahul; Pinaka Pani V. V. S., N.; Kumar, Manoj

    2015-04-01

    The complex terrain region of Patratu, Jharkhand in southern Chota Nagpur of eastern India has high air pollution problems besides complex mesoscale flow and meteorology. The FLEXPART-WRF mesoscale Lagrangian Particle dispersion model is used to simulate the dispersion of elevated effluent releases of nitrogen dioxide (NO2) and suspended particulate matter (SPM) from Patratu thermal power plant over Patratu at a high resolution of 1 km. The WRF is integrated with nested domains (27, 9, 3 km resolutions, 51 vertical levels). The relationships for turbulent intensities in the default diffusion parameterization of the Hanna scheme of FLEXPART is modified with new empirical relationships derived as a function of atmospheric stability from one year fast response turbulence measurements from a nearby observational site at Ranchi. The pollutant dispersion simulated by FLEXPART is evaluated with modified version of the model and using the WRF simulated atmospheric flow field and thermodynamical structure with three alternative PBL schemes [Yonsei University (YSU), Asymmetric Convective Model version 2 (ACM2) and Mellor- Yamada Nakanishi and Niino Level 2.5 PBL (MYNN2]. Results indicate that the new turbulence intensity relationships in FLEXPART provide better comparisons for concentrations of NO2 and SPM with available observations relative to the default relationships. Further, the meteorological parameters simulated using YSU significantly reduces the bias in modeled pollutant concentrations in terms of lesser mean absolute error (MAE), root mean square error (RMSE), normalized mean square error (NMSE), fractional bias (FB) and FAC2 (Factor of 2). These parametric tests enabled to fine tune and validate the FLEXPART-WRF dispersion model with YSU PBL physics and improved Hanna relationships to realistically simulate pollution dispersion over complex terrain of the study region. The study demonstrates the utility of high quality turbulence measurements in pollution

  15. Vegetation-hydrology dynamics in complex terrain of semiarid areas: 2. Energy-water controls of vegetation spatiotemporal dynamics and topographic niches of favorability

    NASA Astrophysics Data System (ADS)

    Ivanov, Valeriy Y.; Bras, Rafael L.; Vivoni, Enrique R.

    2008-03-01

    Ecosystems of dry climates are a particularly interesting subject for ecohydrological studies, as water is generally considered to be the key limiting resource. This work focuses on vegetation-water-energy dynamics occurring on the complex terrain of a semiarid area characteristic of central New Mexico. The study employs a mechanistic model of coupled interactions to construct a set of numerical experiments carried out for two small-scale synthetic domains that exhibit particular hillslope curvatures. The linkages between terrain attributes and patterns of C4 grass productivity and water balance components are examined for three generic soil types. It is argued that in conditions of negligible moisture exchange, aspect and slope are the key determinants of both the hydrologic behavior and the degree of site "favorability" to vegetation. Certain topographic locations are more favorable to vegetation, as compared to a flat horizontal surface not influenced by lateral effects. These locations are associated with sites of northerly aspect with surface slopes within a narrow range of magnitudes. Contributions from both rainfall and radiation forcings are discussed to explain the existence of these topographic niches. The sensitivity of results is investigated by modifying the dominant mechanism of lateral water transfer. Two additional controlling topographic features are explored, corresponding to the contiguous and global terrain convergence levels. It is argued that their effects on vegetation-hydrology dynamics at a given location are characteristically superimposed with the impact of site-specific terrain attributes. Furthermore, the results lead to a conceptual relationship linking vegetation-hydrology quantities at different landscape locations.

  16. Effect of thermal stability/complex terrain on wind turbine model(s): a wind tunnel study to address complex atmospheric conditions

    NASA Astrophysics Data System (ADS)

    Guala, M.; Hu, S. J.; Chamorro, L. P.

    2011-12-01

    Turbulent boundary layer measurements in both wind tunnel and in the near-neutral atmospheric surface layer revealed in the last decade the significant contribution of the large scales of motions to both turbulent kinetic energy and Reynolds stresses, for a wide range of Reynolds number. These scales are known to grow throughout the logarithmic layer and to extend several boundary layer heights in the streamwise direction. Potentially, they are a source of strong unsteadiness in the power output of wind turbines and in the aerodynamic loads of wind turbine blades. However, the large scales in realistic atmospheric conditions deserves further study, with well controlled boundary conditions. In the atmospheric wind tunnel of the St. Anthony Falls Laboratory, with a 16 m long test section and independently controlled incoming flow and floor temperatures, turbulent boundary layers in a range of stability conditions, from the stratified to the convective case, can be reproduced and monitored. Measurements of fluctuating temperature, streamwise and wall normal velocity components are simultaneously obtained by an ad hoc calibrated and customized triple-wire sensor. A wind turbine model with constant loading DC motor, constant tip speed ratio, and a rotor diameter of 0.128m is used to mimic a large full scale turbine in the atmospheric boundary layer. Measurements of the fluctuating voltage generated by the DC motor are compared with measurements of the blade's angular velocity by laser scanning, and eventually related to velocity measurements from the triple-wire sensor. This study preliminary explores the effect of weak stability and complex terrain (through a set of spanwise aligned topographic perturbations) on the large scales of the flow and on the fluctuations in the wind turbine(s) power output.

  17. 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

  18. 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.

  19. 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

  20. 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

    2015-05-01

    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.

  1. 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.

  2. 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

  3. Influence of the diagnostic wind field model on the results of calculation of the microscale atmospheric dispersion in moderately complex terrain

    NASA Astrophysics Data System (ADS)

    Kovalets, Ivan V.; Korolevych, Vladimir Y.; Khalchenkov, Alexander V.; Ievdin, Ievgen A.; Zheleznyak, Mark J.; Andronopoulos, Spyros

    2013-11-01

    The impact of diagnostic wind field model on the results of calculation of microscale atmospheric dispersion in moderately complex terrain conditions was investigated. The extensive radiological and meteorological data set collected at the site of the research reactor of the Chalk River Laboratories (CRL) in Canada had been compared with the results of calculations of the Local Scale Model Chain of the EU nuclear emergency response system JRODOS. The diagnostic wind field model based on divergence minimizing procedure and the atmospheric dispersion model RIMPUFF were used in calculations. Taking into account complex topography features with the use of diagnostic wind field model improved the results of calculations. For certain months, the level of improvement of the normalized mean squared error reached the factor of 2. For the whole simulation period (January-July, 2007) the level of improvement by taking into account terrain features with the diagnostic wind field model was about 9%. The use of diagnostic wind field model also significantly improved the fractional bias of the calculated results. Physical analysis of the selected cases of atmospheric dispersion at the CRL site had been performed.

  4. Factors associated with collaboration among agencies serving children with complex chronic conditions.

    PubMed

    Nageswaran, Savithri; Golden, Shannon L; Easterling, Douglas; O'Shea, T Michael; Hansen, William B; Ip, Edward H

    2013-11-01

    Our objective was to identify agency-level factors that increase collaborative relationships between agencies that serve children with complex chronic conditions (CCC). We hypothesized that an agency will collaborate with more partners in the network if the agency had a coordinator and participated in a community coalition. We surveyed representatives of 63 agencies that serve children with CCC in Forsyth County, North Carolina about their agencies' collaborations with other agencies. We used social network analytical methods and exponential random graph analysis to identify factors associated with collaboration among agencies. The unit of analysis was the collaborative tie (n = 3,658) between agencies in the network. Agencies participating in a community coalition were 1.5 times more likely to report collaboration than agencies that did not participate in a coalition. Presence of a coordinator in an agency was not associated with the number of collaborative relationships. Agencies in existence for a longer duration (≥11 vs. ≤10 years; adjusted odds ratio (aOR): 2.1) and those with a higher proportion of CCC clientele (aOR: 2.1 and 1.6 for 11-30 % and ≥31 % compared to ≤10 %) had greater collaboration. Care coordination agencies and pediatric practices reported more collaborative relationships than subspecialty clinics, home-health agencies, durable medical equipment companies, educational programs and family-support services. Collaborative relationships between agencies that serve children with CCC are increased by coalition participation, longer existence and higher CCC clientele. Future studies should evaluate whether interventions to improve collaborations among agencies will improve clinical outcomes of children with CCC. PMID:22555946

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. Improving mesoscale QPF in regions of complex terrain using a fine-scaled nested model and satellite-retrieved data

    NASA Astrophysics Data System (ADS)

    Kuligowski, Robert Joseph

    2000-10-01

    Quantitative precipitation forecasting (QPF) has importance for a broad variety of applications, from agricultural and construction interests to flood forecasting. Both the accuracy and timeliness of QPF are crucial components in its usefulness, especially for hydrologic forecasting, but in general the present state of QPF is lacking in both areas. This thesis approaches QPF from a numerical weather prediction (NWP) model on two fronts. The first is to present a NWP model for predicting short-term precipitation at very fine scales (1-km) over regions with highly variable terrain, and an example from the Pocono Mountains in Pennsylvania is presented. The second is to improve the performance of the NWP model by using satellite data to estimate the initial fields of temperature and moisture used in the model. This use of satellite data has two steps. The first is to produce retrievals of temperature and moisture at individual points using an artificial neural network (ANN) trained on collocated satellite and radiosonde data. The second step is to us a fractal disaggregation scheme to re-scale the satellite images that are at three different horizontal resolutions to the fine spatial resolution of the NWP model. The results show that the fine-scale NWP model using the satellite- retrieved initial conditions has slightly better skill at predicting precipitation than a comparable model, but that the model variables not replaced with satellite- retrieved values still exert a significant influence on the model solution.

  10. 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.

  11. 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

  12. Downscaling and predictability of historical monthly mean surface winds over a region of complex terrain and marine influence: Western Canada

    NASA Astrophysics Data System (ADS)

    Curry, C.; van der Kamp, D.; Monahan, A. H.

    2010-12-01

    valleys and ocean channels. Predictability at stations in regions of relatively flat terrain was less dependent on wind direction. The latter stations also displayed region-wide seasonal shifts in the direction of the most skillfully predicted wind component. In summary, at most stations in Western Canada, monthly mean vector wind components were more reliably predicted than wind speeds. This result complicates the assessment of local changes in mean wind speed, extremes, and wind energy under climate change that is often a desired outcome of the downscaling exercise using modelled fields as predictors. However, useful projections might still be obtained at stations where a single wind direction is dominant.

  13. Observation of the Spatio-Temporal Variability of Snowmelt and Runoff Generation During Rain-on-Snow in a Catchment With Complex Terrain

    NASA Astrophysics Data System (ADS)

    Garvelmann, J.; Pohl, S.; Weiler, M.

    2015-12-01

    Rain-on-snow (ROS) is a typical flood type in montane catchments with temperate climates in many parts of the world and their frequency will most likely increase under changing climate conditions. These flood events have been notoriously hard to predict due to their complex nature and the lack of high resolution spatial and temporal data that could be used for model evaluation and detailed investigations of how a ROS event actually develops in a catchment. The presented study will focus on the spatio-temporal variability of the snow cover distribution, snowmelt energy dynamics, and runoff generation during two ROS events in December 2012 by using hourly measurements of 30 standalone snow monitoring stations set-up in a mesoscale montane catchment in the Black Forest region of southwestern Germany. A multiple linear regression analysis using elevation, aspect, and land cover as predictors for the snow water equivalent distribution within the catchment was applied on an hourly basis. The generated snowmelt water, liquid precipitation, as well as the total retention storage of the snow cover were considered in order to estimate the amount of water potentially available for runoff. The study shows in a very high spatial and temporal resolution how the observed ROS floods developed in the catchment. It became evident that the distributed retention capacity of the snow cover is a crucial mechanism during ROS. Due to higher amounts of snow and increased rainfall in the higher parts of the catchment, elevation was the most important terrain feature for runoff generation. South-facing terrain contributed more water to runoff than north-facing slopes, and only slightly more runoff was generated at open compared to forested areas. The results highlight the importance of the combination of snowmelt together with liquid precipitation for the generation of flood runoff during ROS events and the large temporal and spatial variability of the relevant processes.

  14. 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

  15. Remote sensing of earth terrain

    NASA Technical Reports Server (NTRS)

    Kong, J. A.

    1989-01-01

    A mathematically rigorous and fully polarimetric radar clutter model used to evaluate the radar backscatter from various types of terrain clutter such as forested areas, vegetation canopies, snow covered terrains, or ice fields is presented. With this model, the radar backscattering coefficients for the multichannel polarimetric radar returns can be calculated, in addition to the complex cross correlation coefficients between elements of the polarimetric measurement vector. The complete polarization covariance matrix can be computed and the scattering properties of the clutter environment characterized over a broad range of incident angle and frequencies.

  16. Boundary layer dynamics and its parameterization over the central Himalayas: A step towards improved weather and air quality forecasting over complex terrain

    NASA Astrophysics Data System (ADS)

    Solanki, R.

    2015-12-01

    This study aims towards understanding the boundary layer (BL) dynamics and its parameterization, with observations carried out at ARIES, Manora Peak (29.4⁰ N, 79.5⁰ E, 1960 amsl) in the central Himalayas. The site is located over a complex mountainous terrain and the measurements made with Radar Wind Profiler (RWP), ultrasonic anemometer at two levels and a micro pulse LiDAR are being incorporated in this study. Measurement of local BL has been conducted using 1290 MHz radar wind profiler (RWP) as a part of major field campaign, GVAX. The RWP provides 24 hour diurnal cycle of the BL dynamical state over the site. The general criterion of peak in SNR profile being considered as mixed layer (ML) height was found to be inadequate. Therefore, a new approach is implemented according to which the region of SNR above 6 dB was taken as ML. The maxima in monthly-mean ML height is observed to vary from 557 ± 200 m in November (late autumn) to 912 ± 318 m during March (early spring). As a continuation of this study we have attempted to understand the micrometeorology of the site with fast-response measurements (25 Hz) of temperature and wind at two levels above ground using ultrasonic anemometer. These observations are used to derive diurnal variations of surface layer micro-meteorological parameters during fair-weather conditions. Turbulence and gust characteristics of wind over the site have also been parameterized to provide input for dispersion modeling and understand aerosol distribution over the Himalayas. These observations are consolidated with observations of aerosol vertical distribution made with LIDAR for 2 years, identifying the influences on aerosol loadings from IGP via BL evolution and convective mixing. A strong seasonality in aerosol vertical profile within lower 4 km is observed. Finally, these measurements are used to evaluate high resolution (5 km x 5 km) simulations from the Weather Research and Forecasting (WRF) model. Model simulated and measured

  17. 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.

  18. Using ground truth-validated, large-scale airborne Lidar to assess the accuracy of the SNODAS hydrological model in complex terrain

    NASA Astrophysics Data System (ADS)

    Hedrick, A. R.; Marshall, H.; Elder, K.; Yueh, S. H.

    2013-12-01

    Airborne Light Detection and Ranging (Lidar) is quickly becoming one of the most sought-after methods for obtaining high-resolution seasonal snow depth measurements over enormous areas. Large-scale information of this nature is of significant importance to water managers, hydrologists and the remote sensing community in general. However, Lidar can have a relatively high degree of measurement uncertainty stemming from GPS drift and other factors, which are highly magnified in complex mountain terrain. Simultaneous in situ measurements in concurrence with a Lidar survey are shown to be paramount for constraining absolute and relative uncertainty. During the second Cold Lands Processes eXperiment (CLPX-II) two repeated extensive Lidar surveys (~750 km^2) were flown over northern Colorado. Within the survey area, twelve 500x500 meter intensive observation sites were chosen to represent distinct terrain and vegetation characteristics and at each of these locations approximately 50 depth measurements were made in a predetermined hourglass shape. These in situ measurements were statistically compared to the remotely sensed depths to quantify the error of the Lidar-derived snow depths. The results of the comparison reveal that airborne Lidar-derived snow depth measurements can be poorly suited for characterization of shallow snow packs, but fare better in deeper conditions. Finally, information on the overall Lidar error was then applied to the remainder of the CLPX-II Lidar data set, and subsequently used to evaluate the accuracy of the SNODAS hydrologic model. Utilizing hundreds of 1-km^2 SNODAS pixels situated in high accumulation areas where Lidar measurements of snow depth are relatively more accurate, the root-mean-square difference between the SNODAS-modeled and median Lidar-observed snow depths were found to be on the order of 10-30 centimeters. Conveniently, Lidar surveys also provide information on some of the factors that attribute to relative uncertainty (e

  19. 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.

  20. Vegetation-hydrology dynamics in complex terrain of semiarid areas: 1. A mechanistic approach to modeling dynamic feedbacks

    NASA Astrophysics Data System (ADS)

    Ivanov, Valeriy Y.; Bras, Rafael L.; Vivoni, Enrique R.

    2008-03-01

    Vegetation, particularly its dynamics, is the often-ignored linchpin of the land-surface hydrology. This work emphasizes the coupled nature of vegetation-water-energy dynamics by considering linkages at timescales that vary from hourly to interannual. A series of two papers is presented. A dynamic ecohydrological model [tRIBS + VEGGIE] is described in this paper. It reproduces essential water and energy processes over the complex topography of a river basin and links them to the basic plant life regulatory processes. The framework focuses on ecohydrology of semiarid environments exhibiting abundant input of solar energy but limiting soil water that correspondingly affects vegetation structure and organization. The mechanisms through which water limitation influences plant dynamics are related to carbon assimilation via the control of photosynthesis and stomatal behavior, carbon allocation, stress-induced foliage loss, as well as recruitment and phenology patterns. This first introductory paper demonstrates model performance using observations for a site located in a semiarid environment of central New Mexico.

  1. 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.

  2. Smoke dispersion modeling over complex terrain using high resolution meteorological data and satellite observations - The FireHub platform

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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 2002-2013. 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.

  3. High-resolution spatial databases of monthly climate variables (1961-2010) over a complex terrain region in southwestern China

    NASA Astrophysics Data System (ADS)

    Wu, Wei; Xu, An-Ding; Liu, Hong-Bin

    2015-01-01

    Climate data in gridded format are critical for understanding climate change and its impact on eco-environment. The aim of the current study is to develop spatial databases for three climate variables (maximum, minimum temperatures, and relative humidity) over a large region with complex topography in southwestern China. Five widely used approaches including inverse distance weighting, ordinary kriging, universal kriging, co-kriging, and thin-plate smoothing spline were tested. Root mean square error (RMSE), mean absolute error (MAE), and mean absolute percentage error (MAPE) showed that thin-plate smoothing spline with latitude, longitude, and elevation outperformed other models. Average RMSE, MAE, and MAPE of the best models were 1.16 °C, 0.74 °C, and 7.38 % for maximum temperature; 0.826 °C, 0.58 °C, and 6.41 % for minimum temperature; and 3.44, 2.28, and 3.21 % for relative humidity, respectively. Spatial datasets of annual and monthly climate variables with 1-km resolution covering the period 1961-2010 were then obtained using the best performance methods. Comparative study showed that the current outcomes were in well agreement with public datasets. Based on the gridded datasets, changes in temperature variables were investigated across the study area. Future study might be needed to capture the uncertainty induced by environmental conditions through remote sensing and knowledge-based methods.

  4. Modeling Feasibility of a Proposed Renewable Energy System with Wind and Solar Resources and Hydro Storage in Complex Terrain

    NASA Astrophysics Data System (ADS)

    Jiang, J.; Koracin, D.; Hamilton, R.; Hagen, D.; King, K. C.

    2012-04-01

    High temporal and spatial variability in wind and solar power brings difficulties in integrating these resources into an electricity grid. These difficulties are even more emphasized in areas with complex topography due to complicated flow patterns and cloudiness evolution. This study investigates the feasibility and efficiency of a proposed renewable energy system with wind and solar resources and hydro storages in western Nevada, U.S.A. The state-of-the-art Weather Research and Forecasting (WRF) model was used for the prediction of wind fields and incoming solar radiation at the ground surface. Forecast winds and solar radiation were evaluated with observational data from four wind masts and four meteorological towers in two months, July 2007 and January 2010. Based on a hypothetical wind farm and an assumed neighboring solar power plant both located near the hydro storage facility, as well as considering local power demand, the efficiency of the renewable energy system is projected. One of the main questions was how to optimize a schedule of activating pump storages according to the characteristics of several available hydro pumps, and wind and/or solar power predictions. The results show that segmentation of the pump-storage channel provides improved efficiency of the entire system. This modeled renewable energy system shows promise for possible applications and grid integration.

  5. 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

  6. 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

  7. Terrain types and local-scale stratigraphy of grooved terrain on ganymede

    NASA Technical Reports Server (NTRS)

    Murchie, Scott L.; Head, James W.; Helfenstein, Paul; Plescia, Jeffrey B.

    1986-01-01

    Grooved terrain is subdivided on the basis of pervasive morphology into: (1) groove lanes - elongate parallel groove bands, (2) grooved polygons - polygonal domains of parallel grooves, (3) reticulate terrain - polygonal domains of orthogonal grooves, and (4) complex grooved terrain - polygons with several complexly cross-cutting groove sets. Detailed geologic mapping of select areas, employing previously established conventions for determining relative age relations, reveals a general three-stage sequence of grooved terrain emplacement: first, dissection of the lithosphere by throughgoing grooves, and pervasive deformation of intervening blocks; second, extensive flooding and continued deformation of the intervening blocks; third, repeated superposition of groove lanes concentrated at sites of initial throughgoing grooves. This sequence is corroborated by crater-density measurements. Dominant orientations of groove sets are parallel to relict zones of weakness that probably were reactivated during grooved terrain formation. Groove lane morphology and development consistent with that predicted for passive rifts suggests a major role of global expansion in grooved terrain formation.

  8. 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

  9. 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.

  10. 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.

  11. Turbulence regimes and the validity of similarity theory in the stable boundary layer over complex terrain of the Loess Plateau, China

    NASA Astrophysics Data System (ADS)

    Liang, Jiening; Zhang, Lei; Wang, Ying; Cao, Xianjie; Zhang, Qiang; Wang, Hongbin; Zhang, Beidou

    2014-05-01

    To gain an insight into the characteristics of turbulence in a stable boundary layer over the complex terrain of the Loess Plateau, data from the Semi-Arid Climate and Environment Observatory of Lanzhou University are analyzed. We propose a method to identify and efficiently isolate nonstationary motions from turbulence series, and then we examine the characteristics of nonstationary motions (nonstationary motions refer to gusty events on a greater scale than local shear-generated turbulence). The occurrence frequency of nonstationary motions is found to depend on the mean flow, being more frequent in weak wind conditions and vanishing when the wind speed, U, is greater than 3.0 m s-1. When U exceeds the threshold value of 1.0 m s-1 for the gradient Richardson number Ri ≤ 0.3 and 1.5 m s-1 for Ri > 0.3, local shear-generated turbulence on timescales of less than 4 min depends systematically on U with an average rate of 0.05 U. However, for the weak wind condition, neither the mean wind speed nor the stability is an important factor for local turbulence. Then turbulence is categorized into three regimes based on the behaviors of nonstationary motions and local turbulence. Regime 1 considers stationary turbulence with a wind speed greater than 3.0 m s-1, and the Monin-Obukhov similarity theory (MOST) can be used to calculate the turbulence momentum flux. Regime 2 examines intermittent turbulence where the MOST is competent to evaluate the local turbulence momentum flux but not nonstationary motions. Regime 3 involves wind speed that is less than the threshold value, where nonstationary motions are dominant, local turbulence is independent of the mean flow, and where the MOST may well be invalid.

  12. Volcanology of the 2350 B.P. Eruption of Mount Meager Volcanic Complex, British Columbia, Canada: implications for Hazards from Eruptions in Topographically Complex Terrain

    NASA Astrophysics Data System (ADS)

    Hickson, C. J.; Russell, J. K.; Stasiuk, M. V.

    The Pebble Creek Formation (previously known as the Bridge River Assemblage) comprises the eruptive products of a 2350 calendar year B.P. eruption of the Mount Meager volcanic complex and two rock avalanche deposits. Volcanic rocks of the Pebble Creek Formation are the youngest known volcanic rocks of this complex. They are dacitic in composition and contain phenocrysts of plagioclase, orthopyroxene, amphibole, biotite and minor oxides in a glassy groundmass. The eruption was episodic, and the formation comprises fallout pumice (Bridge River tephra), pyroclastic flows, lahars and a lava flow. It also includes a unique form of welded block and ash breccia derived from collapsing fronts of the lava flow. This Merapi-type breccia dammed the Lillooet River. Collapse of the dam triggered a flood that flowed down the Lillooet Valley. The flood had an estimated total volume of 109 m3 and inundated the Lillooet Valley to a depth of at least 30m above the paleo-valley floor 5.5km downstream of the blockage. Rock avalanches comprising mainly blocks of Plinth Assemblage volcanic rocks (an older formation making up part of the Mount Meager volcanic complex) underlie and overlie the primary volcanic units of the Formation. Both rock avalanches are unrelated to the 2350 B.P. eruption, although the post-eruption avalanche may have its origins in the over-steepened slopes created by the explosive phase of the eruption. Much of the stratigraphic complexity evident in the Pebble Creek Formation results from deposition in a narrow, steep-sided mountain valley containing a major river.

  13. 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...

  14. Local-scale stratigraphy of grooved terrain on Ganymede

    NASA Technical Reports Server (NTRS)

    Murchie, Scott L.; Head, James W.; Helfenstein, Paul; Plescia, Jeffrey B.

    1987-01-01

    The surface of the Jovian satellite, Ganymede, is divided into two main units, dark terrain cut by arcuate and subradial furrows, and light terrain consisting largely of areas with pervasive U-shaped grooves. The grooved terrain may be subdivided on the basis of pervasive morphology of groove domains into four terrain types: (1) elongate bands of parallel grooves (groove lanes); (2) polygonal domains of parallel grooves (grooved polygons); (3) polygonal domains of two orthogonal groove sets (reticulate terrain); and (4) polygons having two to several complexly cross-cutting groove sets (complex grooved terrain). Reticulate terrain is frequently dark and not extensively resurfaced, and grades to a more hummocky terrain type. The other three grooved terrain types have almost universally been resurfaced by light material during their emplacement. The sequence of events during grooved terrain emplacement has been investigated. An attempt is made to integrate observed geologic and tectonic patterns to better constrain the relative ages and styles of emplacement of grooved terrain types. A revised model of grooved terrain emplacement is proposed and is tested using detailed geologic mapping and measurement of crater density.

  15. Structure of precipitating systems over Taiwan’s complex terrain during Typhoon Morakot (2009) as revealed by weather radar and rain gauge observations

    NASA Astrophysics Data System (ADS)

    Liou, Yu-Chieng; Wang, Tai-Chi Chen; Tsai, Yi-Chun; Tang, Yu-Shuang; Lin, Pay-Liam; Lee, Yung-An

    2013-12-01

    This study documents from an observational perspective the structure of precipitation systems over the complex topography of Taiwan as Typhoon Morakot (2009) impinged on the island on 8 August 2009. An advanced multiple-Doppler radar synthesis technique particularly designed for dealing with non-flat surfaces is applied to analyze the three-dimensional wind fields over the ocean and terrain. In the northern and southern portion of the analysis domain where the mountain slope is relatively gentle and steep, respectively, the radar reflectivity measurements indicate that the precipitation systems exhibit very distinct features, namely, horizontal translation in the north and abrupt intensification in the south. While still far from the southern mountainous region, a north-south oscillation of an east-west-oriented band of strong radar reflectivity (>40 dBZ) with a horizontal span of 20 km is observed. Along the mountain slopes, the band of strong radar reflectivity has a much wider north-south extent. Both the radar and rain gauge observations show that the major precipitation is primarily confined to the windward side of the mountains. An analysis of the saturated Brunt-Väisälä frequency reveals that the upstream atmosphere is statically unstable, which implies that the lifting of the incoming convective cells by the topography will easily trigger precipitation. Thus, most of the moisture will be consumed before the air reaches the leeward side of the mountains. The long duration and the wide range of heavy precipitation in the mountainous regions resulted in a record-breaking average (over the gauges) rainfall amount of 2000 mm over 4 days. The prevailing winds approaching the mountains are from the west. The cross-barrier wind speed has a maximum (∼40 m s-1) above the mountain crest that can be reasonably explained by a simplified shallow water model. The capability of applying the weather radar to provide a reliable quantitative estimate of the rainfall over

  16. Interaction of valleys and circulation patterns (CPs) on small-scale spatial precipitation distribution in the complex terrain of southern Germany

    NASA Astrophysics Data System (ADS)

    Liu, M.; Bárdossy, A.; Zehe, E.

    2012-12-01

    Topography exerts influence on the spatial precipitation distribution over different scales, known typically at the large scale as the orographic effect, and at the small scale as the wind-drift rainfall (WDR) effect. At the intermediate scale (~ 1-10 km), which is characterized by secondary mountain valleys, topography also demonstrates some effect on the precipitation pattern. This paper investigates such intermediate-scale topographic effect on precipitation patterns, focusing on narrow-steep valleys in the complex terrain in southern Germany, based on the daily observations over a 48-yr period (~ 1960-2007) from a high-density rain-gauge network covering two sub-areas, Baden-Wuerttemberg (BW) and Bayern (BY). Precipitation data at the valley and non-valley stations are compared under consideration of the daily general circulation patterns (CPs) classified by a fuzzy-rule based algorithm. Scatter plots of precipitation against elevation demonstrate a different behavior of valley stations comparing to non-valley stations. A detailed study of the precipitation time series for selected station triplets, each consisting of a valley station, a mountain station and an open station have been investigated by statistical analysis with the Kolmogrov-Smirnov (KS) test supplemented by the one-way analysis of variance (one-way ANOVA) and a graphical comparison of the means. The results show an interaction of valley orientation and the moisture flow direction of the CPs at the intermediate-scale, i.e. when the valley is shielded from the moisture flow, the precipitation amount within the valley is comparable to that on the mountain crest; when the valley is open to the moisture flow, the precipitation within the valley is much less than that on the mountain. Such a phenomenon, whereby the precipitation is "blind" to the valleys at the intermediate scale conditioned on CPs, is defined as the "narrow-valley effect" in this work, and it cannot be captured by the widely used

  17. 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

  18. 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

  19. 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

  20. 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:...

  1. 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...

  2. Perception for rugged terrain

    NASA Technical Reports Server (NTRS)

    Kweon, In SO; Hebert, Martial; Kanade, Takeo

    1989-01-01

    A three-dimensional perception system for building a geometrical description of rugged terrain environments from range image data is presented with reference to the exploration of the rugged terrain of Mars. An intermediate representation consisting of an elevation map that includes an explicit representation of uncertainty and labeling of the occluded regions is proposed. The locus method used to convert range image to an elevation map is introduced, along with an uncertainty model based on this algorithm. Both the elevation map and the locus method are the basis of a terrain matching algorithm which does not assume any correspondences between range images. The two-stage algorithm consists of a feature-based matching algorithm to compute an initial transform and an iconic terrain matching algorithm to merge multiple range images into a uniform representation. Terrain modeling results on real range images of rugged terrain are presented. The algorithms considered are a fundamental part of the perception system for the Ambler, a legged locomotor.

  3. 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

  4. 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.

  5. POTENTIAL FLOW MODEL FOR GAUSSIAN PLUME INTERACTION WITH SIMPLE TERRAIN FEATURES

    EPA Science Inventory

    The theory of turbulent plumes embedded within potential flow fields is discussed for flows modified by special complex terrain situations. Both two-dimensional and three-dimensional isolated terrain obstacles are considered. Concentration estimates are evaluated using a Gaussian...

  6. Leachates: Terrain analysis

    NASA Astrophysics Data System (ADS)

    Lee, G. F.

    The 13 papers in this report deal with the following areas: Part 1: leachates from excavations and fills; evaluation of potential water quality problems associated with highway excavation and fill; quality of seepage and leachate from mine and mill wastes and control of its effects; induced polarization survey of sulfide bearing rocks in eastern Tennessee and western North Carolina; survey of techniques used for predicting leachate quality; identification of source materials for acid leachates in Maryland coastal plain; leachates from excavations and fills; summation. Part 2: terrain analysis for transportation systems; terrain evaluation for highway planning and design.

  7. Sakhalin Island terrain intelligence

    USGS Publications Warehouse

    U.S. Geological Survey Military Geology Branch

    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.

  8. 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.

  9. Skyline based terrain matching

    NASA Technical Reports Server (NTRS)

    Page, Lance A.

    1990-01-01

    Skyline-based terrain matching, a new method for locating the vantage point of stereo camera or laser range-finding measurements on a global map previously prepared by satellite or aerial mapping is described. The orientation of the vantage is assumed known, but its translational parameters are determined by the algorithm. Skylines, or occluding contours, can be extracted from the sensory measurements taken by an autonomous vehicle. They can also be modeled from the global map, given a vantage estimate from which to start. The two sets of skylines, represented in cylindrical coordinates about either the true or the estimated vantage, are employed as 'features' or reference objects common to both sources of information. The terrain matching problem is formulated in terms of finding a translation between the respective representations of the skylines, by approximating the two sets of skylines as identical features (curves) on the actual terrain. The search for this translation is based on selecting the longest of the minimum-distance vectors between corresponding curves from the two sets of skylines. In successive iterations of the algorithm, the approximation that the two sets of curves are identical becomes more accurate, and the vantage estimate continues to improve. The algorithm was implemented and evaluated on a simulated terrain. Illustrations and examples are included.

  10. 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.

  11. 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.

  12. 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...

  13. 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...

  14. 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...

  15. 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...

  16. 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...

  17. 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…

  18. 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

  19. 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

  20. 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.

  1. Representations to support terrain reasoning

    SciTech Connect

    Powell, D.R.; Wright, J.C.; Slentz, G.E.; Knudsen, P.D.

    1988-01-01

    Los Alamos National Laboratory has been cooperating with the Training and Doctrine Command of the US Army to develop a Corps level combat simulation for quick turn around studies. The simulation of ground combat requires representation of combat units, unit activities, command and control, and terrain. This simulation model emphasizes command and control with particular attention to the potential for automating operational planning. As terrain analysis is an essential part of Army operational planning, this has direct influence on the representation of terrain. The availability of digitized terrain makes it feasible to apply computer based techniques to emulate the terrain analysis process for use in the planning cycle. This paper describes processes used to calculate relevant terrain features for use in a simulation model. 13 refs., 6 figs., 6 tabs.

  2. PROGRAM-ORIENTED INFORMATION--A MANAGEMENT SYSTEMS COMPLEX FOR STATE EDUCATION AGENCIES. PART II, MANUAL OF ACCOUNTING AND RELATED FINANCIAL PROCEDURES.

    ERIC Educational Resources Information Center

    FRIEDMAN, BURTON DEAN; AND OTHERS

    THIS DOCUMENT IS THE SECOND PART OF A REPORT, PROGRAM-ORIENTED INFORMATION--A MANAGEMENT SYSTEMS COMPLEX FOR STATE EDUCATION AGENCIES. PART 1, EA 001 170, SUBTITLED "ANALYSIS AND PROPOSALS," CONTAINS AN OUTLINE OF THE NEED FOR A MANAGEMENT SYSTEMS COMPLEX WITHIN EACH STATE EDUCATION AGENCY. THIS DOCUMENT IS A MANUAL PRESENTING THE PROPOSED…

  3. Eastern Siberia terrain intelligence

    USGS Publications Warehouse

    U.S. Geological Survey Military Geology Branch

    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.

  4. 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.

  5. 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

  6. Heterogeneous strain and composite P-T paths: the key for unravelling complex tectonic histories in polymetamorphic high-grade terrains

    NASA Astrophysics Data System (ADS)

    van Reenen, Dirk D.; Smit, C. Andre

    2010-05-01

    Leonid Perchuk calculated the first P-T paths for eclogites almost 40 years ago [1] and since then he has shown that P-T paths if correctly constructed, represent an accurate record of the thermal and dynamic evolution of high-grade metamorphic complexes [2]. This implies that P-T paths might serve as the basis for geodynamic models for the formation and exhumation of such complexes from the lower crustal levels [2]. His continued research in the Limpopo Complex of southern Africa also played an important role in the next direction in the study of complex high-grade polymetamorphic complexes. This new direction involves the link between composite (kinked) P-T paths [5; 6; 8] and the critical role of heterogeneous strain in the development and preservation of distinct granulite facies events at the regional, outcrop, hand specimen, and thin section scales [7; 9; 10]. Heterogeneous deformation that operated on the thin section scale allowed the construction of kinked P-T paths from single thin sections [5; 6; 9] and the integration of the P-T data with structural and isotopic geochronology [7; 9; 10]. D-P-T-t paths thus constructed not only allow the nature of polymetamorphism in the Limpopo Complex of southern Africa to be established, but also assisted in the construction of tectonic models for the evolution of this complex high-grade polymetamorphic complex. This complex evolution is demonstrated by the configuration of a kinked P-T path (5; 9) that reflects the following distinct stages of the multi-cycle D-P-T-t evolution of the Central Zone: (i) the earliest DC1 path reflects the emplacement before ~2.63Ga of the Limpopo Complex at the crustal level of ~20km. The DC1 stage of the D1/M1 exhumation event was accompanied by the formation of early D2A isoclinal folds; (ii) The DC2 stage of the D1/M1 exhumation event reflects the emplacement before ~2.61Ga of the rocks at the crustal level of ~15km. The DC2 stage was accompanied by the formation of major D2B sheath

  7. Alaskan thermokarst terrain and possible Martian analog

    NASA Technical Reports Server (NTRS)

    Gatto, L. W.; Anderson, D. M.

    1975-01-01

    A first-order analog to Martian fretted terrain has been recognized on enhanced, ERTS-1 (Earth Resources Technology Satellite) imagery of Alaskan Arctic thermokarst terrain. The Alaskan analog displays flat-floored valleys and intervalley uplands characteristic of fretted terrain. The thermokarst terrain has formed in a manner similar to one of the processes postulated for the development of the Martian fretted terrain.

  8. 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

  9. 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…

  10. Ganymede varied terrain

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Voyager 2 took this picture of Ganymede on 5 March 1979. It was taken with the narrow-angle camera from a range of 270,000 kilometers. Clear examples of several of the different types of terrain common on Ganymede's surface are visible. The broad light regions running through the older dark areas are the typical grooved structures seen within most of the light regions on Ganymede. Many examples of craters of all ages can be seen in this image, including fresh, bright ray craters, large, subdued circular markings thought to be the 'scars' of large ancient impacts and craters with thin, bright rims a small central crater. The Voyager Project is managed by the Jet Propulsion Laboratory for NASA's Office of Space Science.

  11. 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.

  12. 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.

  13. Ganymede's Varied Terrain

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Voyager 2 took this picture of Ganymede as the spacecraft was nearing its encounter with the ice giant. It was taken from a range of 312,000 kilometers (195,000 miles), and it shows features down to about 5 to 6 kilometers across. Clear examples of several of the different types of terras in common on Ganymede s surface are visible (right).. The boundary of the largest region of dark ancient terrain on Ganymede can be seen to the east (right), revealing some of the light linear features which may be all that remains of a large ancient impact structure similar to the large ring structure on Callisto. The broad light regions running through the image are the typical grooved structures seen within most of the light regions on Ganymede. To the lower left is another example of what might be evidence of large scale lateral motion in Ganymede's crust. The band of grooved terrain (about 100 kilometers wide) in this region appears to be offset by 50 kilometers or more on the left hand edge by a linear feature perpendicular to it. A feature similar to this one was previously discovered by Voyager 1. These are the first clear examples of strike-slip style faulting on any planet other than Earth. Many examples of craters of all ages can be seen in this image, ranging from fresh, bright ray craters to large, subdued circular markings thought to be the 'scars' of large ancient impacts that have been flattened by glacier-like flows.

  14. A geophysical study of oceanic core complexes and surrounding terrain, Mid-Atlantic Ridge 13°N-14°N

    NASA Astrophysics Data System (ADS)

    Mallows, C.; Searle, R. C.

    2012-06-01

    We describe a geophysical study of oceanic core complexes (OCC) and surrounding seafloor on the Mid-Atlantic Ridge at 13°N-14°N and off-axis to ˜1.9 Myr. Data include a detailed, deep-towed side scan sonar, magnetic field and bathymetry survey, supplemented by concurrent sea-surface bathymetry, magnetic field and gravity measurements. Using side scan and bathymetry, we infer areas and relative ages of seafloor volcanism, revealing a complex pattern of melt accretion across the median valley including close to its walls. We estimate tectonic and magmatic extension throughout the area, and find that average tectonic extension since chron 2 on plates containing OCCs is up to three times that on their conjugates. Deep-towed magnetic data reveal asymmetric spreading (faster on OCC-containing plates) and crustal magnetization that is highly heterogeneous on a scale of ˜5 km, suggesting that exhumed domes of OCCs have highly variable lithologies, perhaps comprising both serpentinized peridotite and gabbro. Improved fits to magnetic data are provided by models incorporating ˜45°of OCC footwall rotation. An axial zone of normal magnetization, of presumed Brunhes epoch, has highly variable width and amplitude, with parts of the ridge axis displaying very low or apparently reversed magnetization. Gravity requires that OCCs have dense cores capped by lower density zones several kilometers thick. Gravity data indicate longer term patterns of crustal thickness and melt distribution that are broadly consistent with numerical models of OCC formation and show that waxing magmatism may terminate OCCs.

  15. 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

  16. 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

  17. 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

  18. 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

  19. 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

  20. Robot Would Climb Steep Terrain

    NASA Technical Reports Server (NTRS)

    Kennedy, Brett; Ganino, Anthony; Aghazarian, Hrand; Hogg, Robert; McHerny, Michael; Garrett, Michael

    2007-01-01

    This brief describes the steep terrain access robot (STAR) -- a walking robot that has been proposed for exploring steep terrain on remote planets. The STAR would be able to climb up or down on slopes as steep as vertical, and even beyond vertical to overhangs. Its system of walking mechanisms and controls would be to react forces and maintain stability. To enable the STAR to anchor itself in the terrain on steep slopes to maintain stability and react forces, it would be necessary to equip the tips of the walking legs with new ultrasonic/ sonic drill corers (USDCs) and to develop sensors and control algorithms to enable robust utilization of the USDCs.

  1. U-Pb SHRIMP and Sm-Nd geochronology of granite-gneiss complexes and implications for the evolution of the Central Brazil Archean Terrain

    NASA Astrophysics Data System (ADS)

    Queiroz, Cláudia Lima; Jost, Hardy; da Silva, Luiz Carlos; McNaughton, Neal J.

    2008-07-01

    The paper is a first attempt to unravel the Archean multi-stage metaplutonic assemblage of the Meso/Neoarchean terrane of the State of Goiás, Central Brazil, by means of the U-Pb SHRIMP zircon and Sm-Nd techniques. Two stages of granitic plutonism, spanning ca. 140 m.y., were precisely established for the accretion of the gneiss protoliths. The earliest stage embraces tonalitic to granodioritic and minor granitic orthogneisses with Nd juvenile signature, emplaced from ca. 2845 to ca. 2785 Ma, interpreted as the roots of an early arc. Inherited zircon xenocrysts and Nd isotopic data indicate that the juvenile magmas underwent contamination from a sialic crust as old as 3.3 Ga, from which there are, so far, no recognizable exposures. The second stage comprises granodioritic to granitic gneisses and lasted from ca. 2711 to 2707 Ma. Based on their Nd isotopic signatures and on inherited zircon crystals, their protoliths are interpreted as dominantly crustal-derived. The SHRIMP data from zircon crystals did not depict a Paleoproterozoic overprinting on the Archean gneisses, which is due to geological processes with prevailing temperatures below the isotopic stability of the U/Pb/Th system in the mineral. These processes comprise crustal extension and intrusion of a mafic dike swarm at ca. 2.3 Ga, followed by low grade events mostly related to shear zones between ca. 2.15 and 2.0 Ga. The study also revealed the extent of the Pan- African tectono-thermal overprinting on the Archean orthogneisses. Most of the zircon populations show morphological evidence of metamorphic peripheral recrystallization dated between ca. 750 and 550 Ma. One of the banded gneisses with a crystallization age of ca. 2700 Ma (2 σ) has a more complex zircon population including magmatic new grains, which yielded a precise 206Pb/238U crystallization age of 590 ± 10 Ma (2 σ). These new grains are interpreted to have grown in anatectic veins injected within strongly sheared gneiss.The data

  2. Forecasting urban PM10 and PM2.5 pollution episodes in very stable nocturnal conditions and complex terrain using WRF-Chem CO tracer model

    NASA Astrophysics Data System (ADS)

    Saide, Pablo E.; Carmichael, Gregory R.; Spak, Scott N.; Gallardo, Laura; Osses, Axel E.; Mena-Carrasco, Marcelo A.; Pagowski, Mariusz

    2011-05-01

    This study presents a system to predict high pollution events that develop in connection with enhanced subsidence due to coastal lows, particularly in winter over Santiago de Chile. An accurate forecast of these episodes is of interest since the local government is entitled by law to take actions in advance to prevent public exposure to PM10 concentrations in excess of 150 μg m -3 (24 h running averages). The forecasting system is based on accurately simulating carbon monoxide (CO) as a PM10/PM2.5 surrogate, since during episodes and within the city there is a high correlation (over 0.95) among these pollutants. Thus, by accurately forecasting CO, which behaves closely to a tracer on this scale, a PM estimate can be made without involving aerosol-chemistry modeling. Nevertheless, the very stable nocturnal conditions over steep topography associated with maxima in concentrations are hard to represent in models. Here we propose a forecast system based on the WRF-Chem model with optimum settings, determined through extensive testing, that best describe both meteorological and air quality available measurements. Some of the important configurations choices involve the boundary layer (PBL) scheme, model grid resolution (both vertical and horizontal), meteorological initial and boundary conditions and spatial and temporal distribution of the emissions. A forecast for the 2008 winter is performed showing that this forecasting system is able to perform similarly to the authority decision for PM10 and better than persistence when forecasting PM10 and PM2.5 high pollution episodes. Problems regarding false alarm predictions could be related to different uncertainties in the model such as day to day emission variability, inability of the model to completely resolve the complex topography and inaccuracy in meteorological initial and boundary conditions. Finally, according to our simulations, emissions from previous days dominate episode concentrations, which highlights the

  3. All-terrain vehicle

    SciTech Connect

    Somerton-Rayner, M.

    1986-12-16

    This patent describes an all-terrain vehicle comprising: a chassis; four road wheel axles equally spaced along the chassis; suspension means mounting the axles on the chassis; wheels mounted adjacent both ends of each of the axles, the wheels on the foremost and the rearmost axles being steerably mounted; propulsion and driving means including a single internal combustion engine and gearbox, and first and second transfer boxes both coupled to be driven by the engine through the gearbox; the first transfer box driving the first and third axles and the second transfer box driving the second and fourth axles; means for driving in the alternative all four wheels and only the center two wheels; power-assisted steering gear means operatively connected to the steerably-mounted wheels of the foremost axle; and steering coupling means extending between the steerably-mounted wheels on the foremost and rearmost axles so dimensioned that upon steering of the front wheels, the rear wheels perform castoring constrained to a smaller turning angle and a lower rate of angular movement than the front wheels.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Remote sensing of Earth terrain

    NASA Technical Reports Server (NTRS)

    Kong, Jin AU; Shin, Robert T.; Nghiem, Son V.; Yueh, Herng-Aung; Han, Hsiu C.; Lim, Harold H.; Arnold, David V.

    1990-01-01

    Remote sensing of earth terrain is examined. The layered random medium model is used to investigate the fully polarimetric scattering of electromagnetic waves from vegetation. The model is used to interpret the measured data for vegetation fields such as rice, wheat, or soybean over water or soil. Accurate calibration of polarimetric radar systems is essential for the polarimetric remote sensing of earth terrain. A polarimetric calibration algorithm using three arbitrary in-scene reflectors is developed. In the interpretation of active and passive microwave remote sensing data from the earth terrain, the random medium model was shown to be quite successful. A multivariate K-distribution is proposed to model the statistics of fully polarimetric radar returns from earth terrain. In the terrain cover classification using the synthetic aperture radar (SAR) images, the applications of the K-distribution model will provide better performance than the conventional Gaussian classifiers. The layered random medium model is used to study the polarimetric response of sea ice. Supervised and unsupervised classification procedures are also developed and applied to synthetic aperture radar polarimetric images in order to identify their various earth terrain components for more than two classes. These classification procedures were applied to San Francisco Bay and Traverse City SAR images.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 76 FR 70531 - Tenth Meeting: RTCA Special Committee 217/EUROCAE WG-44: Terrain and Airport Mapping Databases

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-14

    ... Airport Mapping Databases AGENCY: Federal Aviation Administration (FAA), U.S. Department of Transportation... RTCA Special Committee 217/EUROCAE WG-44: Terrain and Airport Mapping Databases: For the tenth meeting... meeting of RTCA Special Committee 217/EUROCAE WG-44: Terrain and Airport Mapping Databases. The...

  19. 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... Airport Mapping Databases. SUMMARY: The FAA is issuing this notice to advise the public of the twelfth meeting, RTCA Special Committee 217, Joint with EUROCAE WG-44, Terrain and Airport Mapping...

  20. Spatial interrelationships between wheat phenology, thermal time, and terrain attributes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Variation of winter wheat (Triticum aestivum L.) phenology across complex terrain has received little attention. Spatial and temporal variability of a stand is important for assessing overall crop status and making key management decisions. The objectives of this study were to quantify the phenologi...

  1. 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.

  2. 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.

  3. Examining Gas Flux Interactions in Wetland-Dominated Permafrost Terrain

    NASA Astrophysics Data System (ADS)

    Kenward, A.; Quinton, W.; Petrone, R.

    2009-05-01

    Northern boreal wetland complexes have been identified as substantial reservoirs for greenhouse gases and play a crucial role in both regional and global carbon budgets. These reservoirs are not only responding to shifts in atmospheric temperatures, but are also under additional pressure from increasing permafrost degradation. This study examines the carbon (CO2) respiration and net ecosystem exchange (NEE) of a high boreal wetland during the 2008 spring melt season, located near Fort Simpson (61o18'N, 121o 18'W), Northwest Territories. Gas flux was monitored daily with a dynamic closed-system chamber at nine sites in order to characterize and compare the gas flux gradients for three terrain types typical of the lower Liard River valley: channel fens, ombrotrophic flat bogs and peat plateaus. Each terrain site shows a clear pattern of increasing respiration rate during the transition period from snowmelt to senescence; however significant variation in this rate of change between terrain types is apparent. In order to determine how the fluxes change for each terrain during a period of active layer growth in relation to each other, controlling environmental variables (soil moisture, air temperature, relative humidity, and photosynthetic active radiation) were measured to derive any significant relationships. Additionally, the spatial variability of parameters such as soil moisture, snow and frost table depth, water table depth, and plant communities were investigated. This provides information on the gas flux characteristics for specific terrain features with implications for predicting the future regional flux for this area as a sink or source for carbon.

  4. 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.

  5. 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

  6. 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.

  7. Remote sensing of earth terrain

    NASA Technical Reports Server (NTRS)

    Kong, J. A.

    1987-01-01

    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 cover are computed from 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.

  8. 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.

  9. 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.

  10. Terrain commander UGS operational trials

    NASA Astrophysics Data System (ADS)

    Steadman, Robert L.

    2004-09-01

    Operational trials of Textron Systems" Terrain Commander unattended ground sensor (UGS) system are described. Terrain Commander is a powerful new concept in surveillance and remote situational awareness. It leverages a diverse suite of sophisticated unattended ground sensors, day/night electro-optics, satellite data communications, and an advanced Windows based graphic user interface. Terrain Commander OASIS (Optical Acoustic SATCOM Integrated Sensor) provides next generation target detection, classification, and tracking through smart sensor fusion of beam-forming acoustic, seismic, passive infrared, and magnetic sensors. With its fully integrated SATCOM system using internet protocols, virtually any site in the world can be monitored from almost any other location. Multiple remote sites such as airfields, landing zones, base perimeters, road junctions, flanks, and border crossings are monitored with ease from a central location. Intruding personnel or vehicles are automatically detected, classified, and imaged. Results from early operational trials in the outback of Australia and in various locations in the US are described. Probability of detection and recognition against a wide variety of targets including personnel, military and civilian vehicles, in-shore watercraft, and low altitude aircraft are discussed. Environments include snow cover, tropical savannah, rainforest, and woodlands. Experience with alternative SATCOM systems during the trials is also touched upon.

  11. 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.

  12. 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.

  13. Cratered terrain in Terra Meridiani

    NASA Technical Reports Server (NTRS)

    2002-01-01

    detached material as well. Instability in the craters doesn't stop there. Other ridges and troughs in the large craters were probably formed by smaller avalanches of loose rock, but . . . what about those gullies? Were they caused by small, dry avalanches too, or could they possibly have been formed by some kind of liquid running down the walls? In the grand search for possible signs of water on the red planet, gullies found in craters around Mars have been a source of speculation and great interest. The walls of several craters in this image show vague hints of possible gully formation, and features like 'alcoves' above the individual gullies suggest a possible 'formation by fluid.' And yet, gullies are usually found in the south of Mars, not along the equatorial region where these craters are located. So, . . . who knows? This area will take a lot of further study. A long, snaky channel also winds its way up from the bottom of this image, only to be obliterated in its path by the large crater pits that came later. Eroded and old, the channel is far less dramatic than the large impact craters, but leaves a record of more ancient processes on Mars. Dappled in light and dark terrain, the texture of this cratered region of Mars is actually quite complex, especially when you look at the close-up image. Beyond the predominant craters, a smattering of smaller, shallower craters dot the surface, and signs of bright dunes can be found as well.

  14. 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.

  15. Banded Terrain in East Hellas

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-460, 22 August 2003

    This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) narrow angle camera image shows banded terrain in easternmost Hellas Planitia, between the distal ends of Dao and Harmakhis valleys. These bands probably indicate the location of eroded, layered bedrock that has been covered by a mantling deposit that, itself, became eroded to form the very small pits and bumps that pervade the region. This picture is located near 41.1oS, 275.0oW. Sunlight illuminates the scene from the left/upper left.

  16. 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.

  17. Terrain classification for a UGV

    NASA Astrophysics Data System (ADS)

    Sarwal, Alok; Baker, Chris; Rosenblum, Mark

    2005-05-01

    This work addresses the issue of Terrain Classification that can be applied for path planning for an Unmanned Ground Vehicle (UGV) platform. We are interested in classification of features such as rocks, bushes, trees and dirt roads. Currently, the data is acquired from a color camera mounted on the UGV as we can add range data from a second sensor in the future. The classification is accomplished by first, coarse segmenting a frame and then refining the initial segmentations through a convenient user interface. After the first frame, temporal information is exploited to improve the quality of the image segmentation and help classification adapt to changes due to ambient lighting, shadows, and scene changes as the platform moves. The Mean Shift Classifier algorithm provides segmentation of the current frame data. We have tested the above algorithms with four sequence of frames acquired in an environment with terrain representative of the type we expect to see in the field. A comparison of the results from this algorithm was done with accurate manually-segmented (ground-truth) data, for each frame in the sequence.

  18. Remote sensing of earth terrain

    NASA Technical Reports Server (NTRS)

    Kong, J. A.

    1988-01-01

    Two monographs and 85 journal and conference papers on remote sensing of earth terrain have been published, sponsored by NASA Contract NAG5-270. A multivariate K-distribution is proposed to model the statistics of fully polarimetric data from earth terrain with polarizations HH, HV, VH, and VV. In this approach, correlated polarizations of radar signals, as characterized by a covariance matrix, are treated as the sum of N n-dimensional random vectors; N obeys the negative binomial distribution with a parameter alpha and mean bar N. Subsequently, and n-dimensional K-distribution, with either zero or non-zero mean, is developed in the limit of infinite bar N or illuminated area. The probability density function (PDF) of the K-distributed vector normalized by its Euclidean norm is independent of the parameter alpha and is the same as that derived from a zero-mean Gaussian-distributed random vector. The above model is well supported by experimental data provided by MIT Lincoln Laboratory and the Jet Propulsion Laboratory in the form of polarimetric measurements.

  19. Incorporating scale into digital terrain analysis

    NASA Astrophysics Data System (ADS)

    Dragut, L. D.; Eisank, C.; Strasser, T.

    2009-04-01

    Digital Elevation Models (DEMs) and their derived terrain attributes are commonly used in soil-landscape modeling. Process-based terrain attributes meaningful to the soil properties of interest are sought to be produced through digital terrain analysis. Typically, the standard 3 X 3 window-based algorithms are used for this purpose, thus tying the scale of resulting layers to the spatial resolution of the available DEM. But this is likely to induce mismatches between scale domains of terrain information and soil properties of interest, which further propagate biases in soil-landscape modeling. We have started developing a procedure to incorporate scale into digital terrain analysis for terrain-based environmental modeling (Drăguţ et al., in press). The workflow was exemplified on crop yield data. Terrain information was generalized into successive scale levels with focal statistics on increasing neighborhood size. The degree of association between each terrain derivative and crop yield values was established iteratively for all scale levels through correlation analysis. The first peak of correlation indicated the scale level to be further retained. While in a standard 3 X 3 window-based analysis mean curvature was one of the poorest correlated terrain attribute, after generalization it turned into the best correlated variable. To illustrate the importance of scale, we compared the regression results of unfiltered and filtered mean curvature vs. crop yield. The comparison shows an improvement of R squared from a value of 0.01 when the curvature was not filtered, to 0.16 when the curvature was filtered within 55 X 55 m neighborhood size. This indicates the optimum size of curvature information (scale) that influences soil fertility. We further used these results in an object-based image analysis environment to create terrain objects containing aggregated values of both terrain derivatives and crop yield. Hence, we introduce terrain segmentation as an alternative

  20. 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.

  1. 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.

  2. The need for recognition and implementation of a sinkhole-floodplain hazard designation in urban karst terrains

    NASA Astrophysics Data System (ADS)

    Kemmerly, Phillip

    1981-09-01

    Soluble rock terrains pose increased flood hazards because of a demographic shift from the upper Middle West and metropolitan Northeast to the “Sun Belt.” Approximately one-half of the soluble rock terrains in the continental United States occur in the Sun Belt. Urbanization of karst terrains generally increases the frequency and magnitude of sinkhole flooding and the probability of collapse. Soil erosion attendant with urbanization results in silt deposition in depressions, reducing sinkhole runoff storage capacity and regolith hydraulic conductivity. A new flood-hazard designation termed the sinkhole flood-plain is advocated for use by federal mortgage agencies in karst terrains so that sinkhole-related flooding can be minimized. A four-phase methodology for assessing sinkhole flood hazards in a rapidly urbanizing karst terrain is developed, using examples from central Tennessee and southern Kentucky.

  3. 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.

  4. 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.

  5. 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

  6. 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

  7. 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.

  8. Terrain Classification Using Texture For The ALV

    NASA Astrophysics Data System (ADS)

    Marra, Marty; Dunlay, R. Terry; Mathis, Don

    1989-03-01

    Off-road navigation is a very demanding visual task in which texture can play an important role. Travel on a smooth road or path can be done with greater speed and safety in general than on rough natural terrain. In addition, recognition of off-road terrain types can aid in finding the fastest and safest route through a given area. Implementations of two texture methods for identifying certain terrain features in video imagery are briefly discussed. The first method uses edge and morphological filters to identify roadways from off-road. The second method uses a neural net to identify several terrain types based on color, directional texture, global variance and location in the image. Plans to integrate the terrain labeled image produced by the latter method into the ALV's perception system are also discussed.

  9. A comparison of the updated very high resolution model RegCM3_10km with the previous version RegCM3_25km over the complex terrain of Greece: present and future projections

    NASA Astrophysics Data System (ADS)

    Tolika, Konstantia; Anagnostopoulou, Christina; Velikou, Kondylia; Vagenas, Christos

    2015-08-01

    The ability of a fine resolution regional climate model (10 × 10 km) in simulating efficiently the climate characteristics (temperature, precipitation, and wind) over Greece, in comparison to the previous version of the model with a 25 × 25 km resolution, is examined and analyzed in the present study. Overall, the results showed that the finer resolution model presented a better skill in generating low winter temperatures at high altitudinal areas, the temperature difference between the islands and the surrounding sea, high rainfall totals over the mountainous areas, the thermal storms during summer, and the wind maxima over the Aegean Sea. Regarding the future projections, even though the two models agree on the climatic signal, differences are found mainly to the magnitude of change of the selected parameters. Finally, it was found that at higher pressure levels, the present day projections of the two models do not show significant differences since the topography and terrain does not play such an important role as the general atmospheric circulation.

  10. 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. PMID:24434658

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Remote Sensing of Earth Terrain

    NASA Technical Reports Server (NTRS)

    Kong, J. A.

    1984-01-01

    Theoretical models that are useful and practical in relating remote sensing data to the important physical parameters characterizing Earth terrain are developed. The development of models that are useful in data analysis and interpretation, scene simulation, and developing new remote sensing approaches and techniques is discussed. Numerous theoretical models that are applicable to the active and passive remote sensing of plowed fields, atmospheric precipitation, vegetation, and snow fields were developed. The radiative transfer theory is used to interpret the active and passive data as a function of rain rate. Both the random medium model and the discrete scatterer model is used to study the remote sensing of vegetation fields. Due to the non-spherical geometry of the scatterers there is strong azimuthal dependence in the observed data. Thus, the anisotropic random medium model and the discrete scatterer model with nonspherical particles was developed. In order to relate the remote sensing data to the actual physical parameters, the scattering of electromagnetic waves from randomly distributed dielectric scatterers was studied. Both the rigorous random discrete scatterer theory and the strong fluctuation theory are used to derive the backscattering cross section in terms of the actual physical parameters and the results agree well with the data obtained from the snow fields.

  18. Modified finite-element model for application to terrain-induced mesoscale flows

    SciTech Connect

    Lee, R.L.; Leone, J.M. Jr.; Gresho, P.M.

    1982-11-01

    Terrain-induced mesoscale flows are localized atmospheric motions generated primarily by surface inhomogeneities such as differential heating and irregular terrain. Well-known examples of such flows are sea-and-land breeze circulations, mountain-valley flows, urban heat island circulations and mountain lee waves. A numerical model capable of capturing the details of these frequently complicated flow patterns must often contain a realistic and rather accurate representation of the relevant terrain. Over the last decade, mesoscale models have been developed in which various approaches were used to incorporate variable terrain. In this study, a somewhat unique approach, based on a modified finite element procedure, was used to solve the nonhydrostatic planetary boundary layer equations. The nonhydrostatic and finite element features of the model are particularly advantageous for modeling flows over complex topography. The numerical aspects of the model, the parameterizations currently used, and a few preliminary results are presented.

  19. 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.

  20. Geological terrains and crater frequencies on Ariel

    NASA Astrophysics Data System (ADS)

    Plescia, J. B.

    1987-05-01

    The geological terrain recognized on Ariel using Voyager data is briefly discussed. Crater-size frequency data and surface morphology indicate that Ariel has been completely resurfaced since its accretion. The cratered terrain, the oldest surface on Ariel, may have been the one formed during this initial global resurfacing. Subsequently, Ariel has been partly resurfaced, as reflected by the ridged terrains and the plains. Similar crater frequencies for terrains other than the plain indicate that they are of similar age and formed over a relatively brief period of time. The plains are the youngest unit observed on Ariel. Graben development began before plains formation, as indicated by the presence of plains material partially filling some grabens.

  1. Biologic Analog Science Associated with Lava Terrains

    NASA Astrophysics Data System (ADS)

    Thomas, N. K.; Hamilton, J. C.; Veillet, A.; Muir, C.

    2016-05-01

    The goal of BASALT is to use Hawaiian volcanic terrain to constrain the upper limits of biomass that could have been supported on Mars and how those upper bounds inform future detection requirements for manned missions.

  2. Automatic terrain elevation mapping and registration

    NASA Technical Reports Server (NTRS)

    Ramapriyan, H. K.; Murray, C. W.; Strong, J. P.; Blodget, H. W.

    1984-01-01

    Optimum radar illumination geometries for stereoscopic analysis of surface topography are determined. Correlation and image processing experiments on synthetic aperture radar (SAR) data for improved information extraction are conducted. Model of the geometry of the multiple SIR-B views of the Earth are developed the sensitivity of the derived terrain altitude data to the various system parameters is established. The limits of accuracy of terrain data achievable with shuttle imaging radar (SIR-B) are derived. Algorithms for matching multiple SIR-B images to generate digital terrain maps are developed. Finally, the use of such terrain maps in geometric correction and registration of SIR-B and LANDSAT Thematic Mapper data is demonstrated.

  3. Grooved Terrain in Nippur Sulcus on Ganymede

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Complex sets of ridges and grooves are visible in this image of the Nippur Sulcus region on Jupiter's largest moon Ganymede. NASA's Galileo spacecraft imaged this region as it passed Ganymede during its second orbit through the Jovian system. The Nippur Sulcus region is an example of Bright Terrain on Ganymede which is typified by multiple sets of ridges and grooves. The intersections of these sets reveal complex age relationships. North is to the top of the picture and the sun illuminates the surface from the southeast (lower right). In this image a younger sinuous northwest-southeast trending groove set cuts through and apparently destroys the older east-west trending features on the right of the image, allowing scientists to determine the sequence of events that led to the region's formation. The area contains many impact craters. The large crater in the bottom of the image is about 12 kilometers (8 miles) in diameter.

    The image, centered at 51 degrees latitude and 204 degrees longitude, covers an area approximately 79 kilometers (50 miles) by 57 kilometers (36 miles) across. The resolution is 93 meters (330 feet) per picture element. The images were taken on September 6, 1996 at a range of 9,971 kilometers (6,232 miles) by the solid state imaging (CCD) system on 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Gravity measurements and terrain corrections using a digital terrain model in the NW Himalaya

    NASA Astrophysics Data System (ADS)

    Banerjee, Paramesh

    1998-12-01

    Areas recently gravity surveyed in the NW Himalaya are characterized by high-elevation and high-amplitude topographic undulations. A new method of applying combined Bouguer and terrain corrections using a digital terrain model is highly accurate and offers advantages over conventional techniques by saving efforts and being more flexible. Partitioning parameters for station-dependent inner-zone compartments and station-independent outer zones can be optimally selected for the desired accuracy requirements. A digital terrain database is used to obtain the outer-zone corrections. In the situation of the NW Himalaya surveys, a 1.2 km inner zone is divided into 112 compartments for each station and a digital terrain database containing nearly 16 000 data points for 30″×30″ compartments was applied using the computer program EFFECT.FOR, to compute combined Bouguer and terrain corrections for a 20 km range. The terrain corrections between 20 and 170 km were computed using National Geophysical Data Centre (NGDC) 5'×5' gridded global elevation database. The magnitude of the terrain correction varies between 3 and 50 mGal. The effects of the 20 km range terrain correction are more pronounced on short-medium wavelength anomalies. The Swarghat gravity high is further enhanced while several high-frequency pseudo-anomalies disappear after applying the terrain corrections. The refined Bouguer anomaly varies from -160 mGal at the southern end of the section, to -310 mGal at the northern end, suggesting a Moho depth variation from 45 to nearly 60 km. The steepness of the northward negative gravity gradient, typical for the Himalaya, is considerably reduced after applying a terrain correction for the 170 km range.

  9. A generalized polar coordinate method for sound propagation over large-scale irregular terrain.

    PubMed

    Parakkal, Santosh; Gilbert, Kenneth E; Di, Xiao; Bass, Henry E

    2010-11-01

    The polar coordinate method in You [Ph.D. thesis, The University of Mississippi (1993)] is rederived in differential form and is generalized by defining a local, continuously varying, radius of curvature. The generalization makes it possible to compute sound propagation over arbitrary large-scale terrain where the local radii of curvature are much larger than an acoustic wavelength. For a simple hill, both the original and generalized method are in good agreement with measured low-frequency propagation loss data. The generalized method is applied to more complex terrain in a numerical example. The example demonstrates the utility of the method and also shows that complex terrain can have a significant effect on low-frequency sound propagation, even when the slope angles are small. PMID:21110555

  10. 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.

  11. Rough and Steep Terrain Lunar Surface Mobility

    NASA Technical Reports Server (NTRS)

    Wilcox, Brian

    2005-01-01

    In the summer of 2004, the NASA Exploration Systems Mission Directorate conducted an open call for projects relevant to human and robotic exploration of the Earth-Moon and Mars systems. A project entitled 'Rough and Steep Terrain Lunar Surface Mobility' was submitted by JPL and accepted by NASA. The principal investigator of this project describes the robotic vehicle being developed for this effort, which includes six 'wheels-on-legs' so that it can roll efficiently on relatively smooth terrain but walk (using locked wheels as footpads) when "the going gets rough".

  12. 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.

  13. 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.

  14. AirMSPI Terrain File Explanation

    Atmospheric Science Data Center

    2014-05-02

    AirMSPI Terrain-projected File Name Explanation The file name structure is as follows: ... observation tttt:                 Target name aaa:               Mean viewing angle (reported to the nearest ...

  15. 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 ...

  16. Processes Modifying Cratered Terrains on Pluto

    NASA Astrophysics Data System (ADS)

    Moore, J. M.; Howard, A. D.; 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 July encounter with Pluto by the New Horizons spacecraft permitted imaging of its cratered terrains with scales as high as ~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.

  17. Processes Modifying Cratered Terrains on Pluto

    NASA Astrophysics Data System (ADS)

    Moore, Jeffrey M.; Howard, Alan D.; White, Oliver L.; Umurhan, Orkan M.; Schenk, Paul M.; Beyer, Ross A.; McKinnon, William B.; Singer, Kelsi N.; Spencer, John; Stern, S. A.; Weaver, H. A.; Young, Leslie A.; Ennico, Kimberly; Olkin, Cathy B.

    2015-11-01

    The July encounter with Pluto by the New Horizons spacecraft permitted imaging of its cratered terrains with scales as high as ~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.

  18. 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.

  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. 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

  1. 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.

  2. 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.

  3. Hydrologic Terrain Processing Using Parallel Computing

    NASA Astrophysics Data System (ADS)

    Tarboton, D. G.; Watson, D. W.; Wallace, R. M.; Schreuders, K.; Tesfa, T. K.

    2009-12-01

    Topography in the form of Digital Elevation Models (DEMs), is widely used to derive information for the modeling of hydrologic processes. Hydrologic terrain analysis augments the information content of digital elevation data by removing spurious pits, deriving a structured flow field, and calculating surfaces of hydrologic information derived from the flow field. The increasing availability of high-resolution terrain datasets for large areas poses a challenge for existing algorithms that process terrain data to extract this hydrologic information. This paper will describe parallel algorithms that have been developed to enhance hydrologic terrain pre-processing so that larger datasets can be more efficiently computed. Message Passing Interface (MPI) parallel implementations have been developed for pit removal, flow direction, and generalized flow accumulation methods within the Terrain Analysis Using Digital Elevation Models (TauDEM) package. The parallel algorithm works by decomposing the domain into striped or tiled data partitions where each tile is processed by a separate processor. This method also reduces the memory requirements of each processor so that larger size grids can be processed. The parallel pit removal algorithm is adapted from the method of Planchon and Darboux that starts from a high elevation then progressively scans the grid, lowering each grid cell to the maximum of the original elevation or the lowest neighbor. The MPI implementation reconciles elevations along process domain edges after each scan. Generalized flow accumulation extends flow accumulation approaches commonly available in GIS through the integration of multiple inputs and a broad class of algebraic rules into the calculation of flow related quantities. It is based on establishing a flow field through DEM grid cells, that is then used to evaluate any mathematical function that incorporates dependence on values of the quantity being evaluated at upslope (or downslope) grid cells

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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

  9. Preliminary geologic terrain map of Mercury

    NASA Technical Reports Server (NTRS)

    Trask, N. J.; Guest, J. E.

    1975-01-01

    A geologic terrain map of Mercury has been constructed by use of the photogeologic methods employed for the moon and Mars. The oldest and most widespread unit, intercrater plains, forms nearly level to rolling surfaces on which are superposed numerous secondary impact craters. This unit may represent a very old surface that predates the last heavy bombardment of the inner planets. The effects of this bombardment are recorded in a second widespread unit, heavily cratered terrain, consisting of closely spaced craters and basins from 30 km to several hundred kilometers in diameter. Units formed by excavation of the 1300-km-diameter Caloris basin are widespread on one hemisphere of the planet. The development of the Caloris basin was followed relatively quickly by emplacement of widespread plains materials, most of which are probably volcanic.

  10. Location of Sites Within 'Cryptic Terrain'

    NASA Technical Reports Server (NTRS)

    2007-01-01

    A regional landscape near Mars' south pole is called 'cryptic terrain' because it once defied explanation, but new observations bolster and refine interpretations of how springtime outbursts of carbon-dioxide gas there sculpt intricate patterns and paint seasonal splotches. This map indicates locations of three sites that have been examined within the area of cryptic terrain, informally designated 'Manhattan,' 'Giza' and 'Ithaca.'

    The underlying map offers context of brightness measurements from the Thermal Emission Spectrometer instrument draped over a shaded relief map based on data from the Mars Orbiter Laser Altimeter instrument. Cool colors are areas with a low albedo (dark) and warm colors are areas which have high albedo (bright). Both of those instruments flew on NASA's Mars Global Surveyor orbiter.

  11. 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.

  12. Chronology of heavily cratered terrains on Mercury

    NASA Astrophysics Data System (ADS)

    Marchi, S.; Chapman, C. R.

    2012-12-01

    Imaging of Mercury by Mariner 10 revealed a planet with more extensive plains units than on the Moon. Even in heavily cratered terrain, there is a lack of craters <40 km in diameter, relative to the size-frequency distribution on the Moon, a result attributed to resurfacing by the formation of widespread "intercrater plains". MESSENGER imaging has revealed that the more recent smooth plains are generally the result of widespread volcanism (rather than fluidized impact basin ejecta) and that at least localized volcanism may have persisted until comparatively recent times, despite the crustal contraction evidenced by the numerous lobate scarps. The older intercrater plains may also be volcanic. Here we address the ages of the oldest, most heavily cratered regions on Mercury that may predate most of the visible intercrater plains. We scale to Mercury the lunar crater chronology recently developed by Morbidelli et al., [1] in order to interpret new crater counts on these terrains. We find that these craters are probably not saturated but may have been in equilibrium with a rapid resurfacing process, presumably volcanism that formed the earliest recognized intercrater plains. The crater retention age for this terrain, which contains the oldest large craters on Mercury, is surprisingly young, perhaps hundreds of millions of years younger than the heavily cratered pre-Nectarian terrains on the Moon [2]. These results are important for understanding the early geological and geophysical evolution of Mercury. References: [1] Morbidelli A., Marchi S., Bottke W.F., and Kring D.A. 2012. A sawtooth timeline for the first billion years of the lunar bombardment. Earth and Planetary Science Letters, in press. [2] Marchi S., Bottke W.F., Kring D.A., and Morbidelli A. 2012. The onset of the lunar cataclysm as recorded in its ancient crater populations. Earth and Planetary Science Letters 325, 27-38.

  13. 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

  14. 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.

  15. 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.

  16. Modelling complex terrain effects for wind farm layout optimization

    NASA Astrophysics Data System (ADS)

    Schmidt, Jonas; Stoevesandt, Bernhard

    2014-06-01

    The flow over four analytical hill geometries was calculated by CFD RANS simulations. For each hill, the results were converted into numerical models that transform arbitrary undisturbed inflow profiles by rescaling the effect of the obstacle. The predictions of such models are compared to full CFD results, first for atmospheric boundary layer flow, and then for a single turbine wake in the presence of an isolated hill. The implementation of the models into the wind farm modelling software flapFOAM is reported, advancing their inclusion into a fully modular wind farm layout optimization routine.

  17. Long-range transport and diffusion over complex terrain

    SciTech Connect

    Yamada, T.

    1998-12-31

    Project MOHAVE, Measurement of Haze and Visual Effects (Pitchford and Green) provided a unique set of meteorological and tracer data over the southwestern United States. As part of the project, perfluorocarbon tracer gas (ocPDCH) was released from the Mohave Power Plant (MOPP), a large coal-fired facility in southern Nevada. Previously, Lu and Yamada used three-dimensional atmospheric models HOTMAC and RAPTAD (Yamada and Bunker) to simulate the wind, turbulence, and tracer gas distributions. The modeled tracer gas concentrations were compared with observations. The model`s performance was evaluated statistically. HOTMAC and RAPTAD were again used to examine how variables such as winds, turbulence, plume buoyancy, plume exit velocity, and horizontal grid spacing affect the modeled concentrations at receptor sites which are located as far as 250 km from the source. In this study, sensitivity of the model results to horizontal grid spacing was examined.

  18. 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.

  19. Pitted terrains on Vesta: Thermophysical analysis

    NASA Astrophysics Data System (ADS)

    Capria, M.; Tosi, F.; De Sanctis, M.; Turrini, D.; Ammannito, E.; Capaccioni, F.; Fonte, S.; Frigeri, A.; Longobardo, A.; Palomba, E.; Zambon, F.; Schroeder, S.; Denevi, B.; Williams, D.; Scully, J.; Russell, C.; Raymond, C.

    2014-07-01

    Launched in 2007, the Dawn spacecraft, after one year spent orbiting Vesta, is now on its way to Ceres. In the science payload, the Visible and Infrared mapping spectrometer (VIR) is devoted to the study of the mineralogical composition and thermophysical properties of Vesta's surface [1]. Disk-resolved surface temperatures of Vesta have been determined from the infrared spectra measured by VIR [2]. The observed temperatures, together with a thermophysical model, have been used to constrain the thermal properties of a large part of the surface of the asteroid [3]. The average thermal inertia of the surface is quite low, consistent with a widespread presence of a dust layer. While the global thermal inertia is low, the characterization of its surface in terms of regions showing peculiar thermophysical properties gives us the possibility to identify specific areas with different thermal and structural characteristics. These variations can be linked to strong albedo variations that have been observed, or to other physical and structural characteristics of the first few centimeters of the soil. The highest values of thermal inertia have been determined on areas coinciding with locations where pitted terrains have been found [4]. Pitted terrains, first identified on Mars, have been found in association with 4 craters on Vesta: Marcia, Cornelia, Licinia, and Numisia. The Marcia area is characterized by high hydrogen and OH content [5]. By analogy with Mars, the formation of these terrains is thought to be due to the rapid release of volatiles, triggered by heating from an impact event. A question arises on the origin of volatiles: hydrated minerals, or ground, buried ice? In order to discuss the second hypothesis, we have to assume that a comet impact delivers ice that gets buried under a layer of regolith. Successively, another impact on the same area would give origin to the pitted terrain. The buried ice has obviously to survive for the time between the two impacts

  20. 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.

  1. Rotary-wing aircraft terrain-following/terrain-avoidance system development

    NASA Technical Reports Server (NTRS)

    Dorr, Dan W.

    1986-01-01

    Work being accomplished to develop a real-time, piloted simulation of a helicopter using the vertical motion simulator at NASA Ames is discussed. The trajectory generation algorithm and the flight path controller are described, and the software integration of the entire terrain following/terrain avoidance (TF/TA) system is discussed. Real-time simulation requirements and the unique features of applying TF/TA system to helicopter flight are summarized. Initial results indicate that the system is satisfactory for automatic, low level TF/TA helicopter flight.

  2. GeoSAR program: IFSAR validation and terrain classification from polarimetry

    NASA Astrophysics Data System (ADS)

    Carlisle, Robert G.; Davis, Mark E.

    1996-06-01

    The GeoSAR (geographic synthetic aperture radar) program is a Defense Advanced Research Projects Agency (DARPA) sponsored program organized in cooperation with the Jet Propulsion Laboratory (JPL) and the California Department of Conservation. Some aspects of the program have been existent for almost two years. The technical goal of the program has been the development of rapid-mapping radar technologies, and has now, as its principal challenge, the development of a capability for terrain mapping under foliage. In this paper, we discuss validation of current technology and examine the utility of data products currently produced by the Environmental Research Institute of MIchigan's (ERIM) IFSARE, JPL's TOPSAR, and JPL's AIRSAR. We find that ERIM's X-band IFSARE system produces elevation maps to better than 2-m accuracy. Based on this we determine that TOPSAR elevation maps are accurate to at least 5 m. We also demonstrate the utility of JPL's AIRSAR's L-band radar polarimetry for terrain classification.

  3. 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

  4. 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).

  5. Ladar-based terrain cover classification

    NASA Astrophysics Data System (ADS)

    Macedo, Jose; Manduchi, Roberto; Matthies, Larry H.

    2001-09-01

    An autonomous vehicle driving in a densely vegetated environment needs to be able to discriminate between obstacles (such as rocks) and penetrable vegetation (such as tall grass). We propose a technique for terrain cover classification based on the statistical analysis of the range data produced by a single-axis laser rangefinder (ladar). We first present theoretical models for the range distribution in the presence of homogeneously distributed grass and of obstacles partially occluded by grass. We then validate our results with real-world cases, and propose a simple algorithm to robustly discriminate between vegetation and obstacles based on the local statistical analysis of the range data.

  6. 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.

  7. 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.

  8. A worldwide SRTM terrain database suitable for aviation use

    NASA Astrophysics Data System (ADS)

    Schiefele, J.; Launer, M.; Pschierer, C.; Howland, D.; Dorrell, B.; Fox, M.

    2006-05-01

    In the past Jeppesen has built and distributed worldwide terrain models for several Terrain Awareness and Warning Systems (TAWS) avionics clients. The basis for this model is a 30 arc-second NOAA Globe dataset with higher resolution data used where available (primarily in the US). On a large scale however these terrain models have a 900m (3000ft) resolution with errors that can often add up to 650m (1800ft) vertically. This limits the use of these databases to current TAWS systems and is deemed unusable for other aviation applications like SVS displays that require a more resolute and accurate terrain model. To overcome this deficiency, the target of this project was to develop a new worldwide terrain database providing a consistent terrain model that can be used by current (TAWS) and future applications (e.g. 2D moving maps, vertical situation displays, SVS). The basis for this project is the recently released SRTM data from NGA that provides a more resolute, accurate and consistent worldwide terrain model. The dataset however has holes in the peak and valley regions, desert, and very flat areas due to irrecoverable data capture issues. These voids have been filled using new topography algorithms developed in this project. The error distribution of this dataset has been analyzed in relation to topography, acquisition method and other factors. Based on this analysis, it is now possible to raise the terrain a certain amount, such that it can be guaranteed that only a certain number of real terrain points are higher than the data stored in the terrain database. Using this method, databases for designated confidence levels of 10-3, 10-5 and 10-8 - called TerrainScape level 1 - 3 - have been generated. The final result of the project is a worldwide terrain database with quality factors sufficient for use in a broader range of civil aviation applications.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. T-transformation: traversability analysis for navigation on rugged terrain

    NASA Astrophysics Data System (ADS)

    Ye, Cang; Borenstein, Johann

    2004-09-01

    In order to maneuver autonomously on rough terrain, a mobile robot must constantly decide whether to traverse or circumnavigate terrain features ahead. This ability is called Obstacle Negotiation (ON). A critical aspect of ON is the so-called traversability analysis, which evaluates the level of difficulty associated with the traversal of the terrain. This paper presents a new method for traversability analysis, called T-transformation. It is implemented in a local terrain map as follows: (1) For each cell in the local terrain map, a square terrain patch is defined that symmetrically overlays the cell; (2) a plane is fitted to the data points in the terrain patch using a least-square approach and the slope of the least-squares plane and the residual of the fit are computed and used to calculate the Traversability Index (TI) for that cell; (3) after each cell is assigned a TI value, the local terrain map is transformed into a traversability map. The traversability map is further transformed into a traversability field histogram where each element represents the overall level of difficulty to move along the corresponding direction. Based on the traversability field histogram our reactive ON system then computes the steering and velocity commands to move the robot toward the intended goal while avoiding areas of poor traversability. The traversability analysis algorithm and the overall ON system were verified by extensive simulation. We verified our method partially through experiments on a Segway Robotics Mobility Platform (RMP), albeit only on flat terrain.

  15. Derivation of terrain slope from SAR interferometric phase gradient

    NASA Technical Reports Server (NTRS)

    Wegmueller, Urs; Werner, Charles L.; Rosen, Paul A.

    1994-01-01

    The relationship between the gradient of the interferometric phase and the terrain slope, which, it is thought, would allow a derivation of the terrain slopes without phase unwrapping, is presented. A linear relationship between the interferometric phase gradient and the terrain slopes was found. A quantitative error analysis showed that only very small errors are introduced by these approximations for orbital Synthetic Aperture Radar (SAR) geometries. An example of a slope map for repeat pass interferometry from ERS-1 SAR data is given. A number of direct and indirect applications of the terrain slope are indicated: erosion and avalanche hazard studies, radiometric calibration of SAR data, and normalization of the interferometric correlation coefficient.

  16. Addressing terrain masking in orbital reconnaissance

    NASA Astrophysics Data System (ADS)

    Mehta, Sharad; Cico, Luke

    2012-06-01

    During aerial orbital reconnaissance, a sensor system is mounted on an airborne platform for imaging a region on the ground. The latency between the image acquisition and delivery of information to the end-user is critical and must be minimized. Due to fine ground pixel resolution and a large field-of-view for wide-area surveillance applications, a massive volume of data is gathered and imagery products are formed using a real-time multi-processor system. The images are taken at oblique angles, stabilized and ortho-rectified. The line-of-sight of the sensor to the ground is often interrupted by terrain features such as mountains or tall structures as depicted in Figure1. The ortho-rectification process renders the areas hidden from the line-of sight of the sensor with spurious information. This paper discusses an approach for addressing terrain masking in size, weight, and power (SWaP) and memory-restricted onboard processing systems.

  17. Creating improved ASTER DEMs over glacierized terrain

    NASA Astrophysics Data System (ADS)

    Raup, B. H.; Khalsa, S. S.; Armstrong, R.

    2006-12-01

    Digital elevation models (DEMs) produced from ASTER stereo imagery over glacierized terrain frequently contain data voids, which some software packages fill by interpolation. Even when interpolation is applied, the results are often not accurate enough for studies of glacier thickness changes. DEMs are created by automatic cross-correlation between the image pairs, and rely on spatial variability in the digital number (DN) values for this process. Voids occur in radiometrically homogeneous regions, such as glacier accumulation areas covered with uniform snow, due to lack of correlation. The same property that leads to lack of correlation makes possible the derivation of elevation information from photoclinometry, also known as shape-from-shading. We demonstrate a technique to produce improved DEMs from ASTER data by combining the results from conventional cross-correlation DEM-generation software with elevation information produced from shape-from-shading in the accumulation areas of glacierized terrain. The resulting DEMs incorporate more information from the imagery, and the filled voids more accurately represent the glacier surface. This will allow for more accurate determination of glacier hypsometry and thickness changes, leading to better predictions of response to climate change.

  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. 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.

  2. 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.

  3. 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.

  4. 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

  5. Structures in tessera terrain, Venus: Issues and answers

    NASA Astrophysics Data System (ADS)

    Hansen, Vicki L.; Phillips, Roger J.; Willis, James J.; Ghent, Rebecca R.

    2000-02-01

    Many workers assume that tessera terrain, marked by multiple tectonic lineaments and exposed in crustal plateaus, comprises a global onionskin on Venus. Because tesserae are exposed mostly within crustal plateaus, which exhibit thickened crust, issues of tessera distribution and the mechanism of crustal plateau formation (e.g., mantle downwelling or upwelling) are intimately related. A review of Magellan data indicates that tessera terrain does not form a global onionskin on Venus, although ribbon-bearing tesserae reflect an ancient time of a globally thin lithosphere. Individual tracts of ribbon-bearing tessera terrain formed diachronously, punctuating time and space as individual deep mantle plumes imparted a distinctive rheological and structural signature on ancient thin crust across spatially discrete 1600-2500 km diameter regions above hot mantle plumes. Plume-related magmatic accretion led to crustal thickening at these locations, resulting in crustal plateaus. Crustal plateau surfaces record widespread early extension (ribbon structures) and local, minor perpendicular contraction of a thin, competent layer above a ductile substrate. Within individual evolving crustal plateaus the thickness of the competent layer increased with time, and broad, gentle folds formed along plateau margins and short, variably oriented folds formed in the interior; late complex graben cut folds. Local lava flows accompanied all stages of surface deformation. In contrast to these conclusions, Gilmore et al. [1998] summarized post-Magellan arguments in favor of downwelling models for crustal plateau formation. In light of this discrepancy, we reexamine the regions investigated by these workers and evaluate their arguments against upwelling models. We show that Gilmore et al. [1998] did not differentiate ribbons from graben and therefore their proposed temporal relations are invalid; they disregarded shear fracture ribbons, thus invalidating their criticism of ribbon models; they

  6. 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.

  7. 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.

  8. Computer based terrain analysis for operational planning

    SciTech Connect

    Powell, D.R.

    1987-01-01

    Analysis of operational capability is an ongoing task for military commanders. In peacetime, most analysis is conducted via computer based combat simulations, where selected force structures engage in simulated combat to gain insight into specific scenarios. The command and control (C/sup 2/) mechanisms that direct combat forces are often neglected relative to the fidelity of representation of mechanical and physical entities. C/sup 2/ capabilities should include the ability to plan a mission, monitor execution activities, and redirect combat power when appropriate. This paper discusses the development of a computer based approach to mission planning for land warfare. The aspect emphasized is the computation and representation of relevant terrain features in the context of operational planning.

  9. Mottled terrain - A continuing Martian enigma

    NASA Technical Reports Server (NTRS)

    Scott, D. H.; Underwood, J. R., Jr.

    1991-01-01

    The mottled plains material found in the northern Martian lowlands is discussed in terms of Mariner and Viking images as well as geologic mapping based on Viking images. The mottling in Mariner 9 images of this area was associated with albedo contrasts between bright crater-ejecta blankets and dark intercrater material, and dark-crested knobs. The interpretation of the plains material based on the Mariner images is compared to an interpretation of the higher-quality Viking images. Based on the newer images, the mottled terrain is theorized to be comprised of the four constituent members of the Vastitas Borealis formation of Late Hesperian age. Fluvial, aeolian, and glaciotectonic processes are responsible for the extensive modifications of the apparently volcanic formations. The northern plains are not completely understood in spite of the Viking images, and the varied geology in those plains requires more sampling to confirm the theories.

  10. ATRAN Terrain Sensing Guidance-The Grand-Daddy System

    NASA Astrophysics Data System (ADS)

    Koch, Richard F.; Evans, Donald C.

    1980-12-01

    ATRAN was the pioneer terrain sensing guidance system developed in the 1950 era and deployed in Europe on the Air Force's mobile, ground launched TM-76A MACE cruise missile in the late 1950's and early 1960's. The background, principles and technology are described for this system which was the forerunner of todays modern autonomous standoff terrain sensing guided weapons.

  11. 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)…

  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. 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 80.759 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE MARITIME SERVICES Standards for Computing Public Coast Station VHF Coverage § 80.759 Average terrain elevation. (a)(1) Draw...

  14. 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 80.759 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE MARITIME SERVICES Standards for Computing Public Coast Station VHF Coverage § 80.759 Average terrain elevation. (a)(1) Draw...

  15. An Evaluation of the Appalachian Maryland Regional Educational Service Agency.

    ERIC Educational Resources Information Center

    Puzzuoli, David A.; Stead, Floyd L.

    Educators in Allegany, Garrett, and Washington counties in Western Maryland voluntarily formed the Regional Education Service Agency (RESA) of Appalachian Maryland on the basis of their shared problems (relative isolation from the rest of the state and mountainous, remote terrain with very severe winters). RESA is comprised of public educational…

  16. 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.

  17. "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…

  18. 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…

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. Terrain Commander: a next-generation remote surveillance system

    NASA Astrophysics Data System (ADS)

    Finneral, Henry J.

    2003-09-01

    Terrain Commander is a fully automated forward observation post that provides the most advanced capability in surveillance and remote situational awareness. The Terrain Commander system was selected by the Australian Government for its NINOX Phase IIB Unattended Ground Sensor Program with the first systems delivered in August of 2002. Terrain Commander offers next generation target detection using multi-spectral peripheral sensors coupled with autonomous day/night image capture and processing. Subsequent intelligence is sent back through satellite communications with unlimited range to a highly sophisticated central monitoring station. The system can "stakeout" remote locations clandestinely for 24 hours a day for months at a time. With its fully integrated SATCOM system, almost any site in the world can be monitored from virtually any other location in the world. Terrain Commander automatically detects and discriminates intruders by precisely cueing its advanced EO subsystem. The system provides target detection capabilities with minimal nuisance alarms combined with the positive visual identification that authorities demand before committing a response. Terrain Commander uses an advanced beamforming acoustic sensor and a distributed array of seismic, magnetic and passive infrared sensors to detect, capture images and accurately track vehicles and personnel. Terrain Commander has a number of emerging military and non-military applications including border control, physical security, homeland defense, force protection and intelligence gathering. This paper reviews the development, capabilities and mission applications of the Terrain Commander system.

  5. 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.

  6. 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

  7. 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

  8. 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.

  9. 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

  10. 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.

  11. Ganymede - Dark Terrain in Galileo Regio

    NASA Technical Reports Server (NTRS)

    1996-01-01

    This view of a part of the Galileo Regio region on Jupiter's moon Ganymede shows fine details of the dark terrain that makes up about half of the surface of the planet-sized moon. One of many ancient impact craters in the region is visible at the middle left. The crater is cut by numerous fractures, showing that the ancient crust was highly deformed early in Ganymede's history. Dark areas may have originated from dark material thrown off by dark meteorites hitting the surface in thousands of impact events. In this view, north is to the top and the sun illuminates the surface from the lower left about 58 degrees above the horizon. The area shown, at latitude 19 degrees north, longitude 149 degrees west, is about 19 by 26 kilometers (12 by 16 miles); resolution is about 80 meters (262 feet) per pixel. The image was taken June 27 at a range of 7.652 kilometers (4,755 miles). The Jet Propulsion Laboratory manages the Galileo mission for NASA's Office of Space Science.

  12. All-terrain self-leveling wheelchair.

    PubMed

    Schofield, Andrew; Barrett, Steven

    2014-01-01

    Limited mobility is something that affects approximately 6.8 million Americans. Approximately 1.7 million are using wheelchairs or scooters of some kind to enhance mobility. Everyday obstacles present a challenge to those in a wheelchair. Also, outdoor environments such as campsites, lakes, or even grass fields provide additional challenges for those with limited mobility. This project provides a solution to some of the limitations faced by those in wheelchairs. The wheels and tires of the wheelchair allow navigation through most terrains such as grass, gravel, and sand. Furthermore, as a wheelchair climbs or descends a hill it becomes unstable and the user risks tipping the wheelchair causing injury or even death. The self-leveling wheelchair uses an accelerometer to determine its angle of inclination and depending on user interface choices will display the angle or raise the seat with linear actuators to keep the seat level. This will keep the center of gravity towards the front of the chair when going up a hill and towards the back of the chair when going down a hill. This enhanced stability will give the user the confidence and ability to go places where most traditional wheelchairs can not. The chair has the ability to self-level at up to 45 degree and can provide a manual lift of 6 inches. The design presented in this report is patent pending. PMID:25405455

  13. Young Tectonic Events in Martian Chaotic Terrain

    NASA Astrophysics Data System (ADS)

    Martel, L. M. V.

    2012-03-01

    Examples of recent tectonic activity and subsidence on Mars are expressed in Aureum Chaos, the area of chaotic terrain east of Valles Marineris. So say researchers who have studied the layered deposits of Aureum Chaos and the cross-cutting relationships between scarps, dunes, and a landslide. Mauro Spagnuolo (Universidad de Buenos Aires), Angelo Rossi (International Space Science Institute and Jacobs University Bremen), Ernst Hauber (German Aerospace Center), and Stephan van Gasselt (Freie Universität Berlin) identified fault-related geomorphic features in remote sensing data, specifically a disrupted landslide that they determine to be less than 1.9 million years old. If indeed very recent activity has occurred along faults in Aureum Chaos, then these may be very important sites for studies related to the circulation of fluid or gas through, or out of, these fractures or fissures. Both geologists and astrobiologists would be interested in the implications for the distribution of water in the crust, the aqueous alteration of minerals, and the potential for microenvironments to harbor or sustain life.

  14. 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. PMID:24179426

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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

  2. 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)   ...

  3. 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.

  4. Visual augmentation for night flight over featureless terrain

    NASA Technical Reports Server (NTRS)

    Kaiser, Mary K.; Johnson, Walter W.; Mowafy, Lyn; Hennessy, Robert T.; Matsumoto, Joy A.

    1992-01-01

    Visual augmentation technique based on infrared cueing lights which project from the aircraft to the terrain is proposed to mitigate the problems associated with night flight over regions with featureless terrains. A series of simulation studies evaluated the effectiveness of several cueing light configurations. Results indicate that certain relatively low-cost cueing light configurations can be effectively used as pseudo-flight directors without impairing the pilot's use of available natural cues in the scene. Pilots prefer configurations which provide multiple samples of the forward terrain. Providing several 'look-aheads' helps to resolve potential vehicle/terrain state ambiguities. It is concluded that cueing lights are capable of creating visual patterns which are readily interpreted and translated to control commands, thus providing pilots with intuitive, low-workload decision aids.

  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. 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

  7. 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.

  8. 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.

  9. 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.

  10. Projected technological requirements for remote sensing of terrain variables

    NASA Technical Reports Server (NTRS)

    Hutchinson, C. F.

    1982-01-01

    Contributions of remote sensing to hydrogeomorphology and terrain analysis are reviewed in order to identify characteristics that should receive support in system and sensor configuration planning. Fluvial morphological studies, peak discharge modeling, and hydrogeomorphic floodplain mapping using large scale (1:12,000) to small scale (1:750,000) orbital photography are discussed as well as quantitative assessment of terrain variables for specific applications.

  11. Terrain intelligence Chita Oblast (U.S.S.R.)

    USGS Publications Warehouse

    U.S. Geological Survey

    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.

  12. Analysis of Martian terrains using optical power spectra

    NASA Astrophysics Data System (ADS)

    Wolfe, R. W.; Kaplan, S.

    1980-01-01

    Planetary geological studies are almost entirely based on the analysis of orbital imagery. In the case of Mars, optical power spectra are providing the photogeologist with an additional aid in his task of classification and characterization of diverse terrains. Statistical pattern recognition techniques using optical power spectral data may be especially valuable in subdividing terrain units with characteristics that are only subtly different and in correlation of isolated patches of similar materials that are widely separated on the planet's surface.

  13. A novel technique for mapping the disparity of off-terrain objects

    NASA Astrophysics Data System (ADS)

    Suliman, A.; Zhang, Y.; Al-Tahir, R.

    2016-04-01

    Third-dimension information is of a great importance for several remote sensing applications, such as building detection. The main data-source for these applications is very high resolution (VHR) satellite images which allow detailed mapping of complex environments. Stereo VHR satellite images allow the extraction of two correlated types of third-dimension information: disparity and elevation information. While the disparity is measured directly, the elevation information is derived computationally. To measure the disparity information, two overlapped images are matched. However, for the backward and forward off-nadir VHR stereo images, building facades occlude areas and hence create many data gaps. When the disparity is required to represent only the off-terrain objects, interpolation and normalization techniques are typically used. However, in dense urban environments, these techniques destroy the quality of the generated data. Therefore, this paper proposes a registration-based technique to measure the disparity of the above-ground objects. The technique includes constructing epipolar images and registering them using common terrain- level features to allow direct disparity mapping for the off-terrain objects. After the implementation, the negative effects of occlusion in the off-nadir VHR stereo images are mitigated through direct disparity mapping of the above-ground objects and bypassing the interpolation and normalization steps.

  14. A model for bistatic scattering of electromagnetic waves from foliage covered rough terrain

    NASA Astrophysics Data System (ADS)

    Papa, Robert J.; Tamasanis, Douglas T.

    1991-09-01

    The problem of determining the electromagnetic (EM) power received by an antenna located over foliage covered rough terrain in a bistatic scattering geometry is important and quite complex. A model was developed which can quantitatively determine the effect of a foliage layer on EM waves scattered from rough terrain. The theoretical approximations obtained from this model are compared with data at two levels; the loss in penetrating the foliage and the total normalized scattering cross section sigma degrees. The results of this theoretical modeling are compared with experimental data at two levels. First, the effective dielectric constants for a foliage environment were used to calculate the attenuation constants of coherent waves propagating through a dense forest. The attenuation constants given by the model were compared with data taken at 200MHz, 500MHz and 800MHz, resulting in good agreement. Then, the entire bistatic scattering model was used to calculate an effective normalized scattering cross section (sigma degrees) for a sod field, grass, and forest covered terrain. This was compared with L-band data resulting in excellent agreement between theory and experimental data.

  15. 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

  16. 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.

  17. 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

  18. 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.

  19. Stratigraphy of the layered terrain in Valles Marineris, Mars

    NASA Technical Reports Server (NTRS)

    Komatsu, G.; Strom, Roger G.

    1991-01-01

    The layered terrain in Valles Marineris provides information about its origin and the geologic history of this canyon system. Whether the terrain is sedimentary material deposited in a dry or lacustrine environment, or volcanic material related to the tectonics of the canyon is still controversial. However, recent studies of Gangis Layered Terrain suggests a cyclic sequence of deposition and erosion under episodic lacustrine conditions. The stratigraphic studies are extended to four other occurrences of layered terrains in Valles Marineris in an attempt to correlate and distinguish between depositional environments. The Juvantae Chasma, Hebes Chasma, Ophir and Candor Chasmata, Melas Chasma, and Gangis Layered Terrain were examined. Although there are broad similarities among the layered terrains, no two deposits are exactly alike. This suggests that there was no synchronized regional depositional processes to form all the layered deposits. However, the similar erosional style of the lower massive weakly bedded unit in Hebes, Gangis, and Ophir-Candor suggests it may have been deposited under similar circumstances.

  20. 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.

  1. Structural Analysis and Geodynamic Implications of Tessera Terrain, Venus

    NASA Astrophysics Data System (ADS)

    Hansen, V. L.; Willis, J. J.

    1996-03-01

    Understanding processes of tessera formation is fundamental to Venus tectonic and geodynamic models. We examined tessera terrain in Ishtar Terra, crustal plateaus, and as inliers within the plains using high-resolution Magellan SAR imagery. We describe several major types of tesseraeeach found in specific geologic or geomorphic regions. Fold and S-C tessera terrain are found only in Ishtar Terra; lava flow and basin-and-dome terrains reside within the interior of crustal plateaus, whereas folded ribbon terrain and extended folded terrain comprise margins of crustal plateaus; and star terrain lies within central Phoebe. Inliers are divisible into fracture-dominated and graben-dominated tesserae, which may represent ancient flooded coronae-chasmata and crustal plateaus, respectively. Thus tesserae might form in several tectonic environments, including as a result of (1) subsurface flow in Ishtar Terra, (2) as sequences of surface-layer extension and contraction in crustal plateaus, (3) as highly-extended, previously-deformed crustal plateaus which have deflated or sunken, and become flooded and thus preserved as large plains inliers, and (4) as densely-fractured surface layersfractured as a result of corona and chasma formationwhich have since sunken and become flooded, and thus preserved as isolated, scattered, highly-fractured inliers. If these models of formation are correct, tesserae would not form a global onion skin; they would not represent a globally synchronous unit; they would not record a single period of deformation; and it would not infer a single mechanism for tesserae formation.

  2. Kinematics of running on 'off-road' terrain.

    PubMed

    Creagh, U; Reilly, T; Lees, A

    1998-07-01

    It has been established that running on natural 'off-road' terrain elicits a higher energy demand than running on road. Running on such terrain may also result in changes to the characteristics of the normal running stride. The aim of this study was to investigate biomechanical alterations to stride characteristics during off-road running. Nine female participants were recorded on video while running over three terrain types: surfaced footpath, short grass and long grass. The videos were digitized in order to quantify temporal, displacement and velocity variables. Cycle time was not significantly different between conditions (p = 0.315). Step length decreased (p < 0.01) and both vertical displacement of the hip and knee lift increased significantly (p < 0.01) with increasing difficulty of terrain. Despite assisted pacing, there was a significant decrease in velocity (p < 0.01) with each progressively rougher terrain condition. The peak extension angular velocity of the knee was not affected significantly (p < 0.098) by the terrain despite the fact that there was a significant difference in the peak flexion angular velocity (p < 0.01). It was concluded that participants altered their stride displacement and velocity patterns significantly in response to changes in running surface. PMID:9674375

  3. 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.

  4. 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

  5. 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)

  6. Simulating Sand Behavior through Terrain Subdivision and Particle Refinement

    NASA Astrophysics Data System (ADS)

    Clothier, M.

    2013-12-01

    Advances in computer graphics, GPUs, and parallel processing hardware have provided researchers with new methods to visualize scientific data. In fact, these advances have spurred new research opportunities between computer graphics and other disciplines, such as Earth sciences. Through collaboration, Earth and planetary scientists have benefited by using these advances in hardware technology to process large amounts of data for visualization and analysis. At Oregon State University, we are collaborating with the Oregon Space Grant and IGERT Ecosystem Informatics programs to investigate techniques for simulating the behavior of sand. In addition, we have also been collaborating with the Jet Propulsion Laboratory's DARTS Lab to exchange ideas on our research. The DARTS Lab specializes in the simulation of planetary vehicles, such as the Mars rovers. One aspect of their work is testing these vehicles in a virtual "sand box" to test their performance in different environments. Our research builds upon this idea to create a sand simulation framework to allow for more complex and diverse environments. As a basis for our framework, we have focused on planetary environments, such as the harsh, sandy regions on Mars. To evaluate our framework, we have used simulated planetary vehicles, such as a rover, to gain insight into the performance and interaction between the surface sand and the vehicle. Unfortunately, simulating the vast number of individual sand particles and their interaction with each other has been a computationally complex problem in the past. However, through the use of high-performance computing, we have developed a technique to subdivide physically active terrain regions across a large landscape. To achieve this, we only subdivide terrain regions where sand particles are actively participating with another object or force, such as a rover wheel. This is similar to a Level of Detail (LOD) technique, except that the density of subdivisions are determined by

  7. 41 CFR 101-5.106 - Agency committees.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 41 Public Contracts and Property Management 2 2010-07-01 2010-07-01 true Agency committees. 101-5... COMPLEXES 5.1-General § 101-5.106 Agency committees. (a) Establishment. An occupying agency committee will be established by GSA if one does not exist, to assist the occupying agency, or such other agency...

  8. 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

  9. 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

  10. 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

  11. Investigating the Flux Patterns within the Forest Subcanopy over a Hilly Terrain

    NASA Astrophysics Data System (ADS)

    Juang, J.; Hung, M.; Ding, S.; Chu, H.; Hsia, Y.

    2010-12-01

    The tower-based eddy- covariance (EC) flux measurement could provide a reliable way to quantify the exchange of scalars, energy and momentum across the interface between the atmosphere and the terrestrial ecosystem. However, the ideal assumptions for EC measurement hardly meet the real situation, and it has been well documented that the complex terrain and tall forest canopy could significantly cause complicate situations to underestimate flux measurement. In addition, slope-induced drainage flow and horizontal/vertical mean transport have been suggested to misestimate nocturnal fluxes of the carbon dioxide and energy fluxes through deep forest canopy in hilly