Numerical investigations with WRF about atmospheric features leading to heavy precipitation and flood events over the Central Andes' complex topography

NASA Astrophysics Data System (ADS)

Zamuriano, Marcelo; Brönnimann, Stefan

2017-04-01

It's known that some extremes such as heavy rainfalls, flood events, heatwaves and droughts depend largely on the atmospheric circulation and local features. Bolivia is no exception and while the large scale dynamics over the Amazon has been largely investigated, the local features driven by the Andes Cordillera and the Altiplano is still poorly documented. New insights on the regional atmospheric dynamics preceding heavy precipitation and flood events over the complex topography of the Andes-Amazon interface are added through numerical investigations of several case events: flash flood episodes over La Paz city and the extreme 2014 flood in south-western Amazon basin. Large scale atmospheric water transport is dynamically downscaled in order to take into account the complex topography forcing and local features as modulators of these events. For this purpose, a series of high resolution numerical experiments with the WRF-ARW model is conducted using various global datasets and parameterizations. While several mechanisms have been suggested to explain the dynamics of these episodes, they have not been tested yet through numerical modelling experiments. The simulations captures realistically the local water transport and the terrain influence over atmospheric circulation, even though the precipitation intensity is in general unrealistic. Nevertheless, the results show that Dynamical Downscaling over the tropical Andes' complex terrain provides useful meteorological data for a variety of studies and contributes to a better understanding of physical processes involved in the configuration of these events.

Terrain feature recognition for synthetic aperture radar (SAR) imagery employing spatial attributes of targets

NASA Astrophysics Data System (ADS)

Iisaka, Joji; Sakurai-Amano, Takako

1994-08-01

This paper describes an integrated approach to terrain feature detection and several methods to estimate spatial information from SAR (synthetic aperture radar) imagery. Spatial information of image features as well as spatial association are key elements in terrain feature detection. After applying a small feature preserving despeckling operation, spatial information such as edginess, texture (smoothness), region-likeliness and line-likeness of objects, target sizes, and target shapes were estimated. Then a trapezoid shape fuzzy membership function was assigned to each spatial feature attribute. Fuzzy classification logic was employed to detect terrain features. Terrain features such as urban areas, mountain ridges, lakes and other water bodies as well as vegetated areas were successfully identified from a sub-image of a JERS-1 SAR image. In the course of shape analysis, a quantitative method was developed to classify spatial patterns by expanding a spatial pattern through the use of a series of pattern primitives.

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 stratified flow. Attempting to analyze and understand the very small scale meteorological features in this case brings to light a variety of issues of increasing importance to modern meteorology and modeling of atmospheric flows near complex terrain. Fig. 1 Aerial photograph of stratocumulus cloud vortex just north of Santa Cruz Island on July 16, 2006 at 11:26 PDT (18:26 UTC), viewing toward the southwest. Photo by 'KB' courtesy of Capt. Peter Weiss of SkyWest Airlines.

Ecohydrologic Dynamics in Areas of Complex Topography in Semiarid Ecosystems

NASA Astrophysics Data System (ADS)

Ivanov, V. Y.; Bras, R. L.; Vivoni, E. R.

2008-12-01

Topography strongly affects the state and distribution of vegetation and this control is normally considered to operate through the regulation of the incoming solar radiation and lateral redistribution of water and elements. One of the areas of active research is how plants adjust to terrain effects relative to their location in a landscape and what the implications are for the spatial distribution of the water balance. This study emphasizes the coupled nature of interactions among vegetation-water-energy dynamics and their corresponding controls in complex topography of a semiarid ecosystem. These dynamics are investigated by constructing a coupled modeling system, tRIBS+VEGGIE, based on physical, biochemical, or mechanistic representation of individual processes. In a set of numerical experiments, linkages between terrain attributes, patterns of grass and shrub productivity, and water balance components are examined. For different imposed regimes of lateral water transfer, regions of relative vegetation "favorability" are identified. Their principal controlling mechanisms, as mediated by topographic features of the landscape, are investigated. It is argued that the long-term effects of site-specific and non-local terrain characteristics are superimposed and the key features of the superposition appear to be of the same form, irrespective of the soil hydraulic type or the actual water transport mechanism involved.

Northeast Artificial Intelligence Consortium Annual Report 1986. Volume 5. Building an Intelligent Assistant: The Acquisition, Integration, and Maintenance of Complex Distributed Tasks

DTIC Science & Technology

1988-06-01

extraction nets. TerrainMaps: Tools for physical and pseudo-physical molding and growing of features on terrain and thematic maps. 5-13 + ,m , mmmmmm mmmmm...ok 1) the student neem confused, and 2) the teot for wroag-answerstshold is met Recognizing a confused tudent is admittedly a mabjective and imprecise...you know that GRADE in iine 9 is a control variable? Student: Yes 2. Tutor: OIL What i the value of GRADE at anytime during loop execution? Studam

An X-Band Radar Terrain Feature Detection Method for Low-Altitude SVS Operations and Calibration Using LiDAR

NASA Technical Reports Server (NTRS)

Young, Steve; UijtdeHaag, Maarten; Campbell, Jacob

2004-01-01

To enable safe use of Synthetic Vision Systems at low altitudes, real-time range-to-terrain measurements may be required to ensure the integrity of terrain models stored in the system. This paper reviews and extends previous work describing the application of x-band radar to terrain model integrity monitoring. A method of terrain feature extraction and a transformation of the features to a common reference domain are proposed. Expected error distributions for the extracted features are required to establish appropriate thresholds whereby a consistency-checking function can trigger an alert. A calibration-based approach is presented that can be used to obtain these distributions. To verify the approach, NASA's DC-8 airborne science platform was used to collect data from two mapping sensors. An Airborne Laser Terrain Mapping (ALTM) sensor was installed in the cargo bay of the DC-8. After processing, the ALTM produced a reference terrain model with a vertical accuracy of less than one meter. Also installed was a commercial-off-the-shelf x-band radar in the nose radome of the DC-8. Although primarily designed to measure precipitation, the radar also provides estimates of terrain reflectivity at low altitudes. Using the ALTM data as the reference, errors in features extracted from the radar are estimated. A method to estimate errors in features extracted from the terrain model is also presented.

Simulating Operation of a Complex Sensor Network

NASA Technical Reports Server (NTRS)

Jennings, Esther; Clare, Loren; Woo, Simon

2008-01-01

Simulation Tool for ASCTA Microsensor Network Architecture (STAMiNA) ["ASCTA" denotes the Advanced Sensors Collaborative Technology Alliance.] is a computer program for evaluating conceptual sensor networks deployed over terrain to provide military situational awareness. This or a similar program is needed because of the complexity of interactions among such diverse phenomena as sensing and communication portions of a network, deployment of sensor nodes, effects of terrain, data-fusion algorithms, and threat characteristics. STAMiNA is built upon a commercial network-simulator engine, with extensions to include both sensing and communication models in a discrete-event simulation environment. Users can define (1) a mission environment, including terrain features; (2) objects to be sensed; (3) placements and modalities of sensors, abilities of sensors to sense objects of various types, and sensor false alarm rates; (4) trajectories of threatening objects; (5) means of dissemination and fusion of data; and (6) various network configurations. By use of STAMiNA, one can simulate detection of targets through sensing, dissemination of information by various wireless communication subsystems under various scenarios, and fusion of information, incorporating such metrics as target-detection probabilities, false-alarm rates, and communication loads, and capturing effects of terrain and threat.

Evaluation of High Density Surface Observations in Complex Terrain and Their Contribution to the MM5 Model

DTIC Science & Technology

2007-03-01

westerly surface winds, the existence of a dry-adiabatic lapse rate, and often the appearance of wave cloud features (Oard, 1993). For a long time...indicate that a large-scale mountain wave feature was present across almost the entire western United States. The GFS indicates this was a standing 31... wave and not a propagating feature since it persisted with very little movement from about 0600 UTC 6 Mar until about 0000 UTC 7 Mar. A cross

Mapping the Sedna-Lavinia Region of Venus

NASA Technical Reports Server (NTRS)

Campbell, Bruce A.; Anderson, Ross F.

2008-01-01

Geologic mapping of Venus at 1:5 M scale has shown in great detail the flow complexes of volcanoes, coronae, and shield fields, and the varying structural patterns that differentiate tesserae from corona rims and isolated patches of densely lineated terrain. In most cases, however, the lower-elevation plains between the higher-standing landforms are discriminated only on the basis of potentially secondary features such as late-stage lava flooding or tectonic overprinting. This result, in which volcanoes and tesserae appear as "islands in the sea," places weak constraints on the relative age of large upland regions and the nature of the basement terrain. In this work, we focus on the spatial distribution and topography of densely lineated and tessera units over a large region of Venus, and their relationship to apparently later corona and shield flow complexes. The goal is to identify likely connections between patches of deformed terrain that suggest earlier features of regional extent, and to compare the topography of linked patches with other such clusters as a guide to whether they form larger tracts beneath the plains. Mapping Approach. We are mapping the region from 57S to 57N, 300E-60E. Since the 1:5 M quadrangles emphasize detail of tessera structure and corona/edifice flows, we simply adopt the outlines of these features as they relate to the outcrops of either "densely lineated terrain" or tessera (Fig. 1). The densely lineated material is mapped in many quadrangles based on pervasive structural deformation, typically with a single major axis (in contrast to the overlapping orthogonal patterns on tesserae). This unit definition is often extended to include material of corona rims. We do not at present differentiate between plains units, since earlier efforts show that their most defining attributes may be secondary to the original emplacement (e.g., lobate or sheet-like flooding by thin flow units, tectonic patterns related to regional and localized stress regimes) [1].

Assessing Neurophysiologic Markers for Training and Simulation to Develop Expertise in Complex Cognitive Tasks

DTIC Science & Technology

2010-09-01

analysis process is to categorize the goal according to (Gagné, 2005) domains of learning . These domains are: verbal information, intellectual...to terrain features. The ability to provide a clear verbal description of a unique feature is a learned task that may be separate from the...and experts differently. The process of verbally encoding information on location and providing this description may detract from the primary task of

Impact of Terrain Features for Tactical Network Connectivity

DTIC Science & Technology

2013-09-01

Impact of Terrain Features for Tactical Network Connectivity David Tate Lance Joneckis John Fregeau Corinne Kramer David Sparrow I N S T I T U...2000. I N S T I T U T E F O R D E F E N S E A N A LY S E S IDA Document NS D-5026 Impact of Terrain Features for Tactical Network Connectivity...visibility is acceptable when networks operate over flat terrain. Under our simple LOS model of connectivity, mobility has little impact in such an

High-resolution modelling of atmospheric dispersion of dense gas using TWODEE-2.1: application to the 1986 Lake Nyos limnic eruption

NASA Astrophysics Data System (ADS)

Folch, Arnau; Barcons, Jordi; Kozono, Tomofumi; Costa, Antonio

2017-06-01

Atmospheric dispersal of a gas denser than air can threat the environment and surrounding communities if the terrain and meteorological conditions favour its accumulation in topographic depressions, thereby reaching toxic concentration levels. Numerical modelling of atmospheric gas dispersion constitutes a useful tool for gas hazard assessment studies, essential for planning risk mitigation actions. In complex terrains, microscale winds and local orographic features can have a strong influence on the gas cloud behaviour, potentially leading to inaccurate results if not captured by coarser-scale modelling. We introduce a methodology for microscale wind field characterisation based on transfer functions that couple a mesoscale numerical weather prediction model with a microscale computational fluid dynamics (CFD) model for the atmospheric boundary layer. The resulting time-dependent high-resolution microscale wind field is used as input for a shallow-layer gas dispersal model (TWODEE-2.1) to simulate the time evolution of CO2 gas concentration at different heights above the terrain. The strategy is applied to review simulations of the 1986 Lake Nyos event in Cameroon, where a huge CO2 cloud released by a limnic eruption spread downslopes from the lake, suffocating thousands of people and animals across the Nyos and adjacent secondary valleys. Besides several new features introduced in the new version of the gas dispersal code (TWODEE-2.1), we have also implemented a novel impact criterion based on the percentage of human fatalities depending on CO2 concentration and exposure time. New model results are quantitatively validated using the reported percentage of fatalities at several locations. The comparison with previous simulations that assumed coarser-scale steady winds and topography illustrates the importance of high-resolution modelling in complex terrains.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Orgill, M.M.

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 candidatemore » sites, four areas were considered: site selection, terrain uniqueness and quantification, definition of research problems and research plans. 36 references, 111 figures, 20 tables.« less

Interpretation of laser/multi-sensor data for short range terrain modeling and hazard detection

NASA Technical Reports Server (NTRS)

Messing, B. S.

1980-01-01

A terrain modeling algorithm that would reconstruct the sensed ground images formed by the triangulation scheme, and classify as unsafe any terrain feature that would pose a hazard to a roving vehicle is described. This modeler greatly reduces quantization errors inherent in a laser/sensing system through the use of a thinning algorithm. Dual filters are employed to separate terrain steps from the general landscape, simplifying the analysis of terrain features. A crosspath analysis is utilized to detect and avoid obstacles that would adversely affect the roll of the vehicle. Computer simulations of the rover on various terrains examine the performance of the modeler.

An adaptive surface filter for airborne laser scanning point clouds by means of regularization and bending energy

NASA Astrophysics Data System (ADS)

Hu, Han; Ding, Yulin; Zhu, Qing; Wu, Bo; Lin, Hui; Du, Zhiqiang; Zhang, Yeting; Zhang, Yunsheng

2014-06-01

The filtering of point clouds is a ubiquitous task in the processing of airborne laser scanning (ALS) data; however, such filtering processes are difficult because of the complex configuration of the terrain features. The classical filtering algorithms rely on the cautious tuning of parameters to handle various landforms. To address the challenge posed by the bundling of different terrain features into a single dataset and to surmount the sensitivity of the parameters, in this study, we propose an adaptive surface filter (ASF) for the classification of ALS point clouds. Based on the principle that the threshold should vary in accordance to the terrain smoothness, the ASF embeds bending energy, which quantitatively depicts the local terrain structure to self-adapt the filter threshold automatically. The ASF employs a step factor to control the data pyramid scheme in which the processing window sizes are reduced progressively, and the ASF gradually interpolates thin plate spline surfaces toward the ground with regularization to handle noise. Using the progressive densification strategy, regularization and self-adaption, both performance improvement and resilience to parameter tuning are achieved. When tested against the benchmark datasets provided by ISPRS, the ASF performs the best in comparison with all other filtering methods, yielding an average total error of 2.85% when optimized and 3.67% when using the same parameter set.

Geological mysteries on Ganymede

NASA Technical Reports Server (NTRS)

1997-01-01

This image shows some unusual features on the surface of Jupiter's moon, Ganymede. NASA's Galileo spacecraft imaged this region as it passed Ganymede during its second orbit through the Jovian system. The region is located at 31 degrees latitude, 186 degrees longitude in the north of Marius Regio, a region of ancient dark terrain, and is near the border of a large swathe of younger, heavily tectonised bright terrain known as Nippur Sulcus. Situated in the transitional region between these two terrain types, the area shown here contains many complex tectonic structures, and small fractures can be seen crisscrossing the image. North is to the top-left of the picture, and the sun illuminates the surface from the southeast. This image is centered on an unusual semicircular structure about 33 kilometers (20 miles) across. A 38 kilometer (24 miles) long, remarkably linear feature cuts across its northern extent, and a wide east-west fault system marks its southern boundary. The origin of these features is the subject of much debate among scientists analyzing the data. Was the arcuate structure part of a larger feature? Is the straight lineament the result of internal or external processes? Scientists continue to study this data in order to understand the surface processes occurring on this complex satellite.

The image covers an area approximately 80 kilometers (50 miles) by 52 kilometers (32 miles) across. The resolution is 189 meters (630 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.

Investigation of the relationship of crater depths and diameters in selected regions of Mars

NASA Astrophysics Data System (ADS)

Hsu, Hsin-Jen

2013-03-01

Impact craters are common geomorphological features on Mars. The density of craters is different among various regions. Higher crater density means older terrain. Craters can be divided into two types by the interior morphology: simple and complex. The cavity of Simple craters is bowl-shape, and complex craters display various interior features, such as central peaks. The depth/diameter ratio (d/D) of simple craters is larger than that of complex craters. The transition diameter from simple to complex morphologies ranges between 5 and 10 km, and is commonly cited to be about 7 km in the equatorial regions and 6 km near the poles, but the exact value also could vary with terrain type. In this research, seven regions, Amazonis Planitia, Arabia Terra, Chryse Planitia, Hesperia Planum, Isidis Planitia, Solis/Syria/Sinai Planum, and Terra Sirenum, were selected to investigate the onset diameter of complex craters and the relationship of crater diameter and depth in these regions on Mars in order to understand how the geology affects crater d/D. The analysis revealed that the slopes of the d/D relations are different, and these are linked to the surface material in different regions. The onset diameters in young volcanic regions with stronger material are slightly higher than older volcanic regions, and much higher than that of volatile regions. The research proves the different geological units can affect the morphology and morphometry of craters.

Estimating Slopes In Images Of Terrain By Use Of BRDF

NASA Technical Reports Server (NTRS)

Scholl, Marija S.

1995-01-01

Proposed method of estimating slopes of terrain features based on use of bidirectional reflectivity distribution function (BRDF) in analyzing aerial photographs, satellite video images, or other images produced by remote sensors. Estimated slopes integrated along horizontal coordinates to obtain estimated heights; generating three-dimensional terrain maps. Method does not require coregistration of terrain features in pairs of images acquired from slightly different perspectives nor requires Sun or other source of illumination to be low in sky over terrain of interest. On contrary, best when Sun is high. Works at almost all combinations of illumination and viewing angles.

Wind turbine wake measurement in complex terrain

NASA Astrophysics Data System (ADS)

Hansen, KS; Larsen, GC; Menke, R.; Vasiljevic, N.; Angelou, N.; Feng, J.; Zhu, WJ; Vignaroli, A.; W, W. Liu; Xu, C.; Shen, WZ

2016-09-01

SCADA data from a wind farm and high frequency time series measurements obtained with remote scanning systems have been analysed with focus on identification of wind turbine wake properties in complex terrain. The analysis indicates that within the flow regime characterized by medium to large downstream distances (more than 5 diameters) from the wake generating turbine, the wake changes according to local atmospheric conditions e.g. vertical wind speed. In very complex terrain the wake effects are often “overruled” by distortion effects due to the terrain complexity or topology.

Urban Modification of Convection and Rainfall in Complex Terrain

NASA Astrophysics Data System (ADS)

Freitag, B. M.; Nair, U. S.; Niyogi, D.

2018-03-01

Despite a globally growing proportion of cities located in regions of complex terrain, interactions between urbanization and complex terrain and their meteorological impacts are not well understood. We utilize numerical model simulations and satellite data products to investigate such impacts over San Miguel de Tucumán, Argentina. Numerical modeling experiments show urbanization results in 20-30% less precipitation downwind of the city and an eastward shift in precipitation upwind. Our experiments show that changes in surface energy, boundary layer dynamics, and thermodynamics induced by urbanization interact synergistically with the persistent forcing of atmospheric flow by complex terrain. With urbanization increasing in mountainous regions, land-atmosphere feedbacks can exaggerate meteorological forcings leading to weather impacts that require important considerations for sustainable development of urban regions within complex terrain.

The Geology of Pluto and Charon Through the Eyes of New Horizons

NASA Technical Reports Server (NTRS)

Moore, J. M.; McKinnon, W. B.; Spencer, J. R.; Howard, A. D.; Schenk, P. M.; Beyer, R. A.; Nimmo, F.; Singer, K. N.; Umurhan, O. M.; White, O. L.;

Bayes classification of terrain cover using normalized polarimetric data

NASA Technical Reports Server (NTRS)

Yueh, H. A.; Swartz, A. A.; Kong, J. A.; Shin, R. T.; Novak, L. M.

1988-01-01

The normalized polarimetric classifier (NPC) which uses only the relative magnitudes and phases of the polarimetric data is proposed for discrimination of terrain elements. The probability density functions (PDFs) of polarimetric data are assumed to have a complex Gaussian distribution, and the marginal PDF of the normalized polarimetric data is derived by adopting the Euclidean norm as the normalization function. The general form of the distance measure for the NPC is also obtained. It is demonstrated that for polarimetric data with an arbitrary PDF, the distance measure of NPC will be independent of the normalization function selected even when the classifier is mistrained. A complex Gaussian distribution is assumed for the polarimetric data consisting of grass and tree regions. The probability of error for the NPC is compared with those of several other single-feature classifiers. The classification error of NPCs is shown to be independent of the normalization function.

Facing Uncertainty: The Role of the M1 Abrams Tank in the U.S. Army of 2015-2025

DTIC Science & Technology

2015-06-12

surrounding the role of the main battle tank has in fact been a defining feature of the Anglo -American attitude since World War I.20 The modern main...training to high-intensity combined arms training. To replicate combat operations in complex terrain, IDF soldiers trained in a mock Arab city in

Improved disparity map analysis through the fusion of monocular image segmentations

NASA Technical Reports Server (NTRS)

Perlant, Frederic P.; Mckeown, David M.

1991-01-01

The focus is to examine how estimates of three dimensional scene structure, as encoded in a scene disparity map, can be improved by the analysis of the original monocular imagery. The utilization of surface illumination information is provided by the segmentation of the monocular image into fine surface patches of nearly homogeneous intensity to remove mismatches generated during stereo matching. These patches are used to guide a statistical analysis of the disparity map based on the assumption that such patches correspond closely with physical surfaces in the scene. Such a technique is quite independent of whether the initial disparity map was generated by automated area-based or feature-based stereo matching. Stereo analysis results are presented on a complex urban scene containing various man-made and natural features. This scene contains a variety of problems including low building height with respect to the stereo baseline, buildings and roads in complex terrain, and highly textured buildings and terrain. The improvements are demonstrated due to monocular fusion with a set of different region-based image segmentations. The generality of this approach to stereo analysis and its utility in the development of general three dimensional scene interpretation systems are also discussed.

Role of artesian groundwater in forming Martian permafrost features

NASA Technical Reports Server (NTRS)

Howard, Alan D.

1991-01-01

Various landforms possibly related to formation (growth), movement, or decay of ground ice have been identified on Mars, including fretted terrain (ft) and associated lobate debris aprons (lda), the chaotic terrain, concentric crater fills (ccf), polygonal ground, softened terrain, small domes that are possibly pingos, and curvilinear (fingerprint) features (cuf). Glaciers may also have been present. Some of these may involve ice derived from artesian groundwater. Topical areas of discussion are: Mars groundwater and the location of permafrost features; the ft, lda, ccf, and cuf; role of artesian groundwater in formation of fretted terrain, lobate debris blankets, and concentric crater fills; sources of glacial ice; and pingos and other pseudovolcanic structures.

OLYMPEX Data Workshop: GPM View

NASA Technical Reports Server (NTRS)

Petersen, W.

2017-01-01

OLYMPEX Primary Objectives: Datasets to enable: (1) Direct validation over complex terrain at multiple scales, liquid and frozen precip types, (a) Do we capture terrain and synoptic regime transitions, orographic enhancements/structure, full range of precipitation intensity (e.g., very light to heavy) and types, spatial variability? (b) How well can we estimate space/time-accumulated precipitation over terrain (liquid + frozen)? (2) Physical validation of algorithms in mid-latitude cold season frontal systems over ocean and complex terrain, (a) What are the column properties of frozen, melting, liquid hydrometeors-their relative contributions to estimated surface precipitation, transition under the influence of terrain gradients, and systematic variability as a function of synoptic regime? (3) Integrated hydrologic validation in complex terrain, (a) Can satellite estimates be combined with modeling over complex topography to drive improved products (assimilation, downscaling) [Level IV products] (b) What are capabilities and limitations for use of satellite-based precipitation estimates in stream/river flow forecasting?

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 terrain spatial and textural cues.

Geoelectrical characterisation of basement aquifers: the case of Iberekodo, southwestern Nigeria

NASA Astrophysics Data System (ADS)

Aizebeokhai, Ahzegbobor P.; Oyeyemi, Kehinde D.

2018-03-01

Basement aquifers, which occur within the weathered and fractured zones of crystalline bedrocks, are important groundwater resources in tropical and subtropical regions. The development of basement aquifers is complex owing to their high spatial variability. Geophysical techniques are used to obtain information about the hydrologic characteristics of the weathered and fractured zones of the crystalline basement rocks, which relates to the occurrence of groundwater in the zones. The spatial distributions of these hydrologic characteristics are then used to map the spatial variability of the basement aquifers. Thus, knowledge of the spatial variability of basement aquifers is useful in siting wells and boreholes for optimal and perennial yield. Geoelectrical resistivity is one of the most widely used geophysical methods for assessing the spatial variability of the weathered and fractured zones in groundwater exploration efforts in basement complex terrains. The presented study focuses on combining vertical electrical sounding with two-dimensional (2D) geoelectrical resistivity imaging to characterise the weathered and fractured zones in a crystalline basement complex terrain in southwestern Nigeria. The basement aquifer was delineated, and the nature, extent and spatial variability of the delineated basement aquifer were assessed based on the spatial variability of the weathered and fractured zones. The study shows that a multiple-gradient array for 2D resistivity imaging is sensitive to vertical and near-surface stratigraphic features, which have hydrological implications. The integration of resistivity sounding with 2D geoelectrical resistivity imaging is efficient and enhances near-surface characterisation in basement complex terrain.

Complex terrain influences ecosystem carbon responses to temperature and precipitation

NASA Astrophysics Data System (ADS)

Reyes, W. M.; Epstein, H. E.; Li, X.; McGlynn, B. L.; Riveros-Iregui, D. A.; Emanuel, R. E.

2017-08-01

Terrestrial ecosystem responses to temperature and precipitation have major implications for the global carbon cycle. Case studies demonstrate that complex terrain, which accounts for more than 50% of Earth's land surface, can affect ecological processes associated with land-atmosphere carbon fluxes. However, no studies have addressed the role of complex terrain in mediating ecophysiological responses of land-atmosphere carbon fluxes to climate variables. We synthesized data from AmeriFlux towers and found that for sites in complex terrain, responses of ecosystem CO2 fluxes to temperature and precipitation are organized according to terrain slope and drainage area, variables associated with water and energy availability. Specifically, we found that for tower sites in complex terrain, mean topographic slope and drainage area surrounding the tower explained between 51% and 78% of site-to-site variation in the response of CO2 fluxes to temperature and precipitation depending on the time scale. We found no such organization among sites in flat terrain, even though their flux responses exhibited similar ranges. These results challenge prevailing conceptual framework in terrestrial ecosystem modeling that assumes that CO2 fluxes derive from vertical soil-plant-climate interactions. We conclude that the terrain in which ecosystems are situated can also have important influences on CO2 responses to temperature and precipitation. This work has implications for about 14% of the total land area of the conterminous U.S. This area is considered topographically complex and contributes to approximately 15% of gross ecosystem carbon production in the conterminous U.S.

Coldspots and hotspots - Global tectonics and mantle dynamics of Venus

NASA Technical Reports Server (NTRS)

Bindschadler, Duane L.; Schubert, Gerald; Kaula, William M.

1992-01-01

Based on geologic observations provided by Magellan's first cycle of data collection and recent models of mantle convection in spherical shells and crustal deformation, the major topographic and geologic features of Venus are incorporated into a model of global mantle dynamics. Consideration is given to volcanic rises, such as Beta Regio and Atla Regio, plateau-shaped highlands dominated by complex ridged terrain (e.g., Ovda Regio and Alpha Regio), and circular lowland regions, such as Atalanta Planitia. Each of these features is related to either mantle plumes (hotspots) or mantle downwellings (coldspots).

NPSNET: Dynamic Terrain and Cultured Feature Depiction

DTIC Science & Technology

1992-09-01

defaults. bridge(terrain *ptr, vertex pos, bridge mattype bmat ); This constructor takes only the pointer to the underlying terrain, a placement, and a...material to use for construction. bridge(terrain *ptr, vertex pos, bridge-mattype bmat , float dir); This constructor takes a terrain pointer, a...placement position, a material to use, and a direction to run. bridge(terrain *ptr, vertex pos, bridge-mattype bmat , float dir, float width, float height

Automated thematic mapping and change detection of ERTS-A images. [digital interpretation of Arizona imagery

NASA Technical Reports Server (NTRS)

Gramenopoulos, N. (Principal Investigator)

1973-01-01

The author has identified the following significant results. For the recognition of terrain types, spatial signatures are developed from the diffraction patterns of small areas of ERTS-1 images. This knowledge is exploited for the measurements of a small number of meaningful spatial features from the digital Fourier transforms of ERTS-1 image cells containing 32 x 32 picture elements. Using these spatial features and a heuristic algorithm, the terrain types in the vicinity of Phoenix, Arizona were recognized by the computer with a high accuracy. Then, the spatial features were combined with spectral features and using the maximum likelihood criterion the recognition accuracy of terrain types increased substantially. It was determined that the recognition accuracy with the maximum likelihood criterion depends on the statistics of the feature vectors. Nonlinear transformations of the feature vectors are required so that the terrain class statistics become approximately Gaussian. It was also determined that for a given geographic area the statistics of the classes remain invariable for a period of a month but vary substantially between seasons.

Phase difference statistics related to sensor and forest parameters

NASA Technical Reports Server (NTRS)

Lopes, A.; Mougin, E.; Beaudoin, A.; Goze, S.; Nezry, E.; Touzi, R.; Karam, M. A.; Fung, A. K.

1992-01-01

The information content of ordinary synthetic aperture radar (SAR) data is principally contained in the radiometric polarization channels, i.e., the four Ihh, Ivv, Ihv and Ivh backscattered intensities. In the case of clutter, polarimetric information is given by the four complex degrees of coherence, from which the mean polarization phase differences (PPD), correlation coefficients or degrees of polarization can be deduced. For radiometric features, the polarimetric parameters are corrupted by multiplicative speckle noise and by some sensor effects. The PPD distribution is related to the sensor, speckle and terrain properties. Experimental results are given for the variation of the terrain hh/vv mean phase difference and magnitude of the degree of coherence observed on bare soil and on different pine forest stands.

Are the circular, dark features on Comet Borrelly's surface albedo variations or pits?

USGS Publications Warehouse

Nelson, R.M.; Soderblom, L.A.; Hapke, B.W.

2004-01-01

The highest resolution images of Comet 19P/Borrelly show many dark features which, upon casual inspection, appear to be low albedo markings, but which may also be shadows or other photometric variations caused by a depression in the local topography. In order to distinguish between these two possible interpretations we conducted a photometric analysis of three of the most prominent of these features using six of the highest quality images from the September 22, 2001 Deep Space 1 (DS1) flyby. We find that: 1. The radiance in the darkest parts of each feature increases as phase angle decreases, similarly to the radiance behavior of the higher albedo surrounding terrain. The dark features could be either fully illuminated low albedo spots or, alternatively, they could be depressions. No part of any of the three regions was in full shadow. 2. One of the regions has a radiance profile consistent with a rimmed depression, the second, with a simple depression with no rim, and the third with a low albedo spot. 3. The regolith particles are backscattering and carbon black is one of the few candidate regolith materials that might explain this low albedo. We conclude that Borrelly's surface is geologically complex to the limit of resolution of the images with a combination complex topography, pits, troughs, peaks and ridges, and some very dark albedo markings, perhaps a factor of two to three darker than the average 3-4% albedo of the surrounding terrains. Our technique utilizing measured radiance profiles through the dark regions is able to discriminate between rimmed depressions, rimless depressions and simple albedo changes not associated with topography. ?? 2003 Elsevier Inc. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

2016-10-01

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

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.

Hydrographic Basins Analysis Using Digital Terrain Modelling

NASA Astrophysics Data System (ADS)

Mihaela, Pişleagă; -Minda Codruţa, Bădăluţă; Gabriel, Eleş; Daniela, Popescu

2017-10-01

The paper, emphasis the link between digital terrain modelling and studies of hydrographic basins, concerning the hydrological processes analysis. Given the evolution of computing techniques but also of the software digital terrain modelling made its presence felt increasingly, and established itself as a basic concept in many areas, due to many advantages. At present, most digital terrain modelling is derived from three alternative sources such as ground surveys, photogrammetric data capture or from digitized cartographic sources. A wide range of features may be extracted from digital terrain models, such as surface, specific points and landmarks, linear features but also areal futures like drainage basins, hills or hydrological basins. The paper highlights how the use appropriate software for the preparation of a digital terrain model, a model which is subsequently used to study hydrographic basins according to various geomorphological parameters. As a final goal, it shows the link between digital terrain modelling and hydrographic basins study that can be used to optimize the correlation between digital model terrain and hydrological processes in order to obtain results as close to the real field processes.

Enhancing fuzzy robot navigation systems by mimicking human visual perception of natural terrain traversibility

NASA Technical Reports Server (NTRS)

Tunstel, E.; Howard, A.; Edwards, D.; Carlson, A.

2001-01-01

This paper presents a technique for learning to assess terrain traversability for outdoor mobile robot navigation using human-embedded logic and real-time perception of terrain features extracted from image data.

Using the SWAT model to improve process descriptions and define hydrologic partitioning in South Korea

NASA Astrophysics Data System (ADS)

Shope, C. L.; Maharjan, G. R.; Tenhunen, J.; Seo, B.; Kim, K.; Riley, J.; Arnhold, S.; Koellner, T.; Ok, Y. S.; Peiffer, S.; Kim, B.; Park, J.-H.; Huwe, B.

2014-02-01

Watershed-scale modeling can be a valuable tool to aid in quantification of water quality and yield; however, several challenges remain. In many watersheds, it is difficult to adequately quantify hydrologic partitioning. Data scarcity is prevalent, accuracy of spatially distributed meteorology is difficult to quantify, forest encroachment and land use issues are common, and surface water and groundwater abstractions substantially modify watershed-based processes. Our objective is to assess the capability of the Soil and Water Assessment Tool (SWAT) model to capture event-based and long-term monsoonal rainfall-runoff processes in complex mountainous terrain. To accomplish this, we developed a unique quality-control, gap-filling algorithm for interpolation of high-frequency meteorological data. We used a novel multi-location, multi-optimization calibration technique to improve estimations of catchment-wide hydrologic partitioning. The interdisciplinary model was calibrated to a unique combination of statistical, hydrologic, and plant growth metrics. Our results indicate scale-dependent sensitivity of hydrologic partitioning and substantial influence of engineered features. The addition of hydrologic and plant growth objective functions identified the importance of culverts in catchment-wide flow distribution. While this study shows the challenges of applying the SWAT model to complex terrain and extreme environments; by incorporating anthropogenic features into modeling scenarios, we can enhance our understanding of the hydroecological impact.

Using Visual Odometry to Estimate Position and Attitude

NASA Technical Reports Server (NTRS)

Maimone, Mark; Cheng, Yang; Matthies, Larry; Schoppers, Marcel; Olson, Clark

2007-01-01

A computer program in the guidance system of a mobile robot generates estimates of the position and attitude of the robot, using features of the terrain on which the robot is moving, by processing digitized images acquired by a stereoscopic pair of electronic cameras mounted rigidly on the robot. Developed for use in localizing the Mars Exploration Rover (MER) vehicles on Martian terrain, the program can also be used for similar purposes on terrestrial robots moving in sufficiently visually textured environments: examples include low-flying robotic aircraft and wheeled robots moving on rocky terrain or inside buildings. In simplified terms, the program automatically detects visual features and tracks them across stereoscopic pairs of images acquired by the cameras. The 3D locations of the tracked features are then robustly processed into an estimate of overall vehicle motion. Testing has shown that by use of this software, the error in the estimate of the position of the robot can be limited to no more than 2 percent of the distance traveled, provided that the terrain is sufficiently rich in features. This software has proven extremely useful on the MER vehicles during driving on sandy and highly sloped terrains on Mars.

Quantifying relationships between abundances of cold-water coral Lophelia pertusa and terrain features: A case study on the Norwegian margin

NASA Astrophysics Data System (ADS)

Tong, Ruiju; Purser, Autun; Guinan, Janine; Unnithan, Vikram; Yu, Jinsongdi; Zhang, Chengcheng

2016-03-01

An understanding of how terrain features influence abundance of a particular species greatly aids in the development of accurate predictive habitat suitability models. In this study, we investigated the observed seafloor coverage of cold-water coral Lophelia pertusa in relation to seabed topography at the Sotbakken and Røst Reefs on the Norwegian margin. The primary terrain features at the study sites are a SW-NE stretching mound at Sotbakken Reef and SW-NE running ridges at Røst Reef, located at depths of ~300-400 m and ~250-320 m respectively. Ship-borne multibeam bathymetry data, JAGO dive video data and JAGO positioning data were used in this study. Terrain variables were calculated at scales of 30 m, 90 m and 170 m based on the bathymetry data. Additionally, we investigated the relationships between the terrain variables at multiple scales using the Unweighted Pair Group Method. The observed L. pertusa coverage at both reefs was found to be significantly correlated with most investigated terrain variables, with correlations increasing in strength with increase in analysis scale, suggesting that large scale terrain features likely play an important role in influencing L. pertusa distribution. Small scale terrain variations appear less important in determining the suitability of a region of seafloor for L. pertusa colonization. We conclude that bathymetric position index and curvature, as well as seabed aspect, most strongly correlate with coral coverage, indicating that local topographic highs, with an orientation into inflowing bottom currents, are most suitable for L. pertusa habitation. These results indicate that developing habitat suitability models for L. pertusa will benefit from inclusion of particular key terrain variables (e.g. aspect, plan curvature, mean curvature and slope) and that these should ideally be computed at multiple spatial scales with a greater gap in scales than we used in this study, to maximize the inclusion of the key variables in the model whilst minimizing redundancy.

Large eddy simulation for atmospheric boundary layer flow over flat and complex terrains

NASA Astrophysics Data System (ADS)

Han, Yi; Stoellinger, Michael; Naughton, Jonathan

2016-09-01

In this work, we present Large Eddy Simulation (LES) results of atmospheric boundary layer (ABL) flow over complex terrain with neutral stratification using the OpenFOAM-based simulator for on/offshore wind farm applications (SOWFA). The complete work flow to investigate the LES for the ABL over real complex terrain is described including meteorological-tower data analysis, mesh generation and case set-up. New boundary conditions for the lateral and top boundaries are developed and validated to allow inflow and outflow as required in complex terrain simulations. The turbulent inflow data for the terrain simulation is generated using a precursor simulation of a flat and neutral ABL. Conditionally averaged met-tower data is used to specify the conditions for the flat precursor simulation and is also used for comparison with the simulation results of the terrain LES. A qualitative analysis of the simulation results reveals boundary layer separation and recirculation downstream of a prominent ridge that runs across the simulation domain. Comparisons of mean wind speed, standard deviation and direction between the computed results and the conditionally averaged tower data show a reasonable agreement.

Visual terrain mapping for traversable path planning of mobile robots

NASA Astrophysics Data System (ADS)

Shirkhodaie, Amir; Amrani, Rachida; Tunstel, Edward W.

2004-10-01

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.

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.

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 to areally smaller, but readily recognizable, 'land units.' Many land systems appeared as distinct spectral classes or as acceptably homogeneous combinations of several spectral classes. The digitally classified map corresponded to the general geographic patterns of many of the land systems. Statistical correlation of the digitally classified map and the published map was not possible because the published map showed only land systems whereas the digitally classified map showed some land units as well as systems. The general correspondence of spectral classes to the integrated terrain units means that the digital mapping of the units may precede fieldwork and act as a guide to field sampling and detailed terrain unit description as well as measuring of the location, area, and extent of each unit. Extension of the Landsat mapping and classification technique to other arid and semi-arid regions of the world may be feasible.

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.

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

PubMed

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.

ARC-1989-AC89-7054

NASA Image and Video Library

1989-08-28

Voyager violet, green and ultraviolet images of Triton were map projected into cylindrical coordinates and combines to produce this false-color terrain map. Several compositionally distinct terrain and geologic features are portrayed. At center is a gray-blue unit referred to as 'cantaloupe' terrain because of its unusual topographic texture. The unit appears to predate other units to the left. Immediately adjacent to the cantaloupe terrain, is a smoother unit, represented by a reddish color, that has been dissected by a prominent fault system. This unit apparently overlies a much-higher-albedo material, seen farther left. A prominent angular albedo boundary separates relatively undisturbed smooth terrain from irregular patches which seem to emanate from circular, often bright-centered features. The parallel streaks may represent vented particulate materials blown in the same direction by winds in Triton's thin atmosphere.

FuzzObserver

NASA Technical Reports Server (NTRS)

Howard, Ayanna; Bayard, David

2006-01-01

Fuzzy Feature Observation Planner for Small Body Proximity Observations (FuzzObserver) is a developmental computer program, to be used along with other software, for autonomous planning of maneuvers of a spacecraft near an asteroid, comet, or other small astronomical body. Selection of terrain features and estimation of the position of the spacecraft relative to these features is an essential part of such planning. FuzzObserver contributes to the selection and estimation by generating recommendations for spacecraft trajectory adjustments to maintain the spacecraft's ability to observe sufficient terrain features for estimating position. The input to FuzzObserver consists of data from terrain images, including sets of data on features acquired during descent toward, or traversal of, a body of interest. The name of this program reflects its use of fuzzy logic to reason about the terrain features represented by the data and extract corresponding trajectory-adjustment rules. Linguistic fuzzy sets and conditional statements enable fuzzy systems to make decisions based on heuristic rule-based knowledge derived by engineering experts. A major advantage of using fuzzy logic is that it involves simple arithmetic calculations that can be performed rapidly enough to be useful for planning within the short times typically available for spacecraft maneuvers.

Cross-cutting Relationships of Surface Features on Europa

NASA Technical Reports Server (NTRS)

1997-01-01

This image of Jupiter's moon Europa shows a very complex terrain of ridges and fractures. The absence of large craters and the low number of small craters indicates that this surface is geologically young. The relative ages of the ridges can be determined by using the principle of cross-cutting relationships; i.e. older features are cross-cut by younger features. Using this principle, planetary geologists are able to unravel the sequence of events in this seemingly chaotic terrain to unfold Europa's unique geologic history.

The spacecraft Galileo obtained this image on February 20, 1997. The area covered in this image is approximately 11 miles (18 kilometers) by 8.5 miles (14 kilometers) across, near 15 North, 273 West. North is toward the top of the image, with the sun illuminating from the right.

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

The Impact of Ensemble Kalman Filter Assimilation of Near-Surface Observations on the Predictability of Atmospheric Conditions over Complex Terrain: Results from Recent MATERHORN Field Program

NASA Astrophysics Data System (ADS)

Pu, Z.; Zhang, H.

2013-12-01

Near-surface atmospheric observations are the main conventional observations for weather forecasts. However, in modern numerical weather prediction, the use of surface observations, especially those data over complex terrain, remains a unique challenge. There are fundamental difficulties in assimilating surface observations with three-dimensional variational data assimilation (3DVAR). In our early study[1] (Pu et al. 2013), a series of observing system simulation experiments was performed with the ensemble Kalman filter (EnKF) and compared with 3DVAR for its ability to assimilate surface observations with 3DVAR. Using the advanced research version of the Weather Research and Forecasting (WRF) model, results demonstrate that the EnKF can overcome some fundamental limitations that 3DVAR has in assimilating surface observations over complex terrain. Specifically, through its flow-dependent background error term, the EnKF produces more realistic analysis increments over complex terrain in general. Over complex terrain, the EnKF clearly performs better than 3DVAR, because it is more capable of handling surface data in the presence of terrain misrepresentation. With this presentation, we further examine the impact of EnKF data assimilation on the predictability of atmospheric conditions over complex terrain with the WRF model and the observations obtained from the most recent field experiments of the Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) Program. The MATERHORN program provides comprehensive observations over mountainous regions, allowing the opportunity to study the predictability of atmospheric conditions over complex terrain in great details. Specifically, during fall 2012 and spring 2013, comprehensive observations were collected of soil states, surface energy budgets, near-surface atmospheric conditions, and profiling measurements from multiple platforms (e.g., balloon, lidar, radiosondes, etc.) over Dugway Proving Ground (DPG), Utah. With the near-surface observations and sounding data obtained during the MATERHORN fall 2012 field experiment, a month-long cycled EnKF analysis and forecast was produced with the WRF model and an advanced EnKF data assimilation system. Results are compared with the WRF near real-time forecasting during the same month and a set of analysis with 3DVAR data assimilation. Overall evaluation suggests some useful insights on the impacts of different data assimilation methods, surface and soil states, terrain representation on the predictability of atmospheric conditions over mountainous terrain. Details will be presented. References [1] Pu, Z., H. Zhang, and J. A. Anderson,. 'Ensemble Kalman filter assimilation of near-surface observations over complex terrain: Comparison with 3DVAR for short-range forecasts.' Tellus A, vol. 65,19620. 2013. http://dx.doi.org/10.3402/tellusa.v65i0. 19620.

Charon Complexity

NASA Image and Video Library

2015-09-10

This image of Pluto's largest moon Charon, taken by NASA's New Horizons spacecraft 10 hours before its closest approach to Pluto on July 14, 2015 from a distance of 290,000 miles (470,000 kilometers), is a recently downlinked, much higher quality version of a Charon image released on July 15. Charon, which is 750 miles (1,200 kilometers) in diameter, displays a surprisingly complex geological history, including tectonic fracturing; relatively smooth, fractured plains in the lower right; several enigmatic mountains surrounded by sunken terrain features on the right side; and heavily cratered regions in the center and upper left portion of the disk. There are also complex reflectivity patterns on Charon's surface, including bright and dark crater rays, and the conspicuous dark north polar region at the top of the image. The smallest visible features are 2.9 miles 4.6 kilometers) in size. http://photojournal.jpl.nasa.gov/catalog/PIA19932

Selection method of terrain matching area for TERCOM algorithm

NASA Astrophysics Data System (ADS)

Zhang, Qieqie; Zhao, Long

2017-10-01

The performance of terrain aided navigation is closely related to the selection of terrain matching area. The different matching algorithms have different adaptability to terrain. This paper mainly studies the adaptability to terrain of TERCOM algorithm, analyze the relation between terrain feature and terrain characteristic parameters by qualitative and quantitative methods, and then research the relation between matching probability and terrain characteristic parameters by the Monte Carlo method. After that, we propose a selection method of terrain matching area for TERCOM algorithm, and verify the method correctness with real terrain data by simulation experiment. Experimental results show that the matching area obtained by the method in this paper has the good navigation performance and the matching probability of TERCOM algorithm is great than 90%

Martian Buried Basins and Implications for Characteristics of the Burial Layer and Underlying Surface

NASA Technical Reports Server (NTRS)

Sarid, A. R.; Frey, H. V.; Roark, J. H.

2003-01-01

Deciphering the cratering record on Mars has been challenging because it may reflect the changes in both the population of impactors and in the resurfacing processes on Mars. However, it is possible to determine the breadth of impactors captured in the cratering record. Extensive areas of resurfacing are of particular interest because they likely contain material from various ages in Martian history. By deducing the impact populations in both surface and underlying layers of terrain, it is possible to determine the age of the layers and constrain theories on the development of the Martian surface. However, to do so requires a method of seeing impact features which are no longer visible. Topographic data of Mars, taken by the Mars Orbiter Laser Altimeter (MOLA), has revealed impact features buried by resurfacing processes. These features are often indistinguishable on Viking images of the Martian surface. In this study, gridded MOLA data was analyzed in order to locate buried impact features, also called buried basins, in Syria, Solis, and Sinai Planum just south of Valles Marineris. The population statistics of buried features can be compared to those of visible features in order to determine the age of the underlying material and characteristics of the surface cover. Specifically, if the buried population in the Hesperian terrain is similar to the population of visible features in the Noachian, it would suggest that the underlying terrain is Noachian in age. The buried craters can then be compared to visible Noachian craters to reveal the amount of deterioration of the buried features. These comparisons allow us to explore the morphology of the terrain in the Hesperian region to determine if topographic variations are due to differences in the thickness of the overlying material or are a characteristic of the underlying terrain.

Investigation of Error Patterns in Geographical Databases

NASA Technical Reports Server (NTRS)

Dryer, David; Jacobs, Derya A.; Karayaz, Gamze; Gronbech, Chris; Jones, Denise R. (Technical Monitor)

2002-01-01

The objective of the research conducted in this project is to develop a methodology to investigate the accuracy of Airport Safety Modeling Data (ASMD) using statistical, visualization, and Artificial Neural Network (ANN) techniques. Such a methodology can contribute to answering the following research questions: Over a representative sampling of ASMD databases, can statistical error analysis techniques be accurately learned and replicated by ANN modeling techniques? This representative ASMD sample should include numerous airports and a variety of terrain characterizations. Is it possible to identify and automate the recognition of patterns of error related to geographical features? Do such patterns of error relate to specific geographical features, such as elevation or terrain slope? Is it possible to combine the errors in small regions into an error prediction for a larger region? What are the data density reduction implications of this work? ASMD may be used as the source of terrain data for a synthetic visual system to be used in the cockpit of aircraft when visual reference to ground features is not possible during conditions of marginal weather or reduced visibility. In this research, United States Geologic Survey (USGS) digital elevation model (DEM) data has been selected as the benchmark. Artificial Neural Networks (ANNS) have been used and tested as alternate methods in place of the statistical methods in similar problems. They often perform better in pattern recognition, prediction and classification and categorization problems. Many studies show that when the data is complex and noisy, the accuracy of ANN models is generally higher than those of comparable traditional methods.

Automated thematic mapping and change detection of ERTS-A images

NASA Technical Reports Server (NTRS)

Gramenopoulos, N. (Principal Investigator)

1975-01-01

The author has identified the following significant results. In the first part of the investigation, spatial and spectral features were developed which were employed to automatically recognize terrain features through a clustering algorithm. In this part of the investigation, the size of the cell which is the number of digital picture elements used for computing the spatial and spectral features was varied. It was determined that the accuracy of terrain recognition decreases slowly as the cell size is reduced and coincides with increased cluster diffuseness. It was also proven that a cell size of 17 x 17 pixels when used with the clustering algorithm results in high recognition rates for major terrain classes. ERTS-1 data from five diverse geographic regions of the United States were processed through the clustering algorithm with 17 x 17 pixel cells. Simple land use maps were produced and the average terrain recognition accuracy was 82 percent.

Environmental modeling and recognition for an autonomous land vehicle

NASA Technical Reports Server (NTRS)

Lawton, D. T.; Levitt, T. S.; Mcconnell, C. C.; Nelson, P. C.

1987-01-01

An architecture for object modeling and recognition for an autonomous land vehicle is presented. Examples of objects of interest include terrain features, fields, roads, horizon features, trees, etc. The architecture is organized around a set of data bases for generic object models and perceptual structures, temporary memory for the instantiation of object and relational hypotheses, and a long term memory for storing stable hypotheses that are affixed to the terrain representation. Multiple inference processes operate over these databases. Researchers describe these particular components: the perceptual structure database, the grouping processes that operate over this, schemas, and the long term terrain database. A processing example that matches predictions from the long term terrain model to imagery, extracts significant perceptual structures for consideration as potential landmarks, and extracts a relational structure to update the long term terrain database is given.

Radar-derived quantitative precipitation estimation in complex terrain over the eastern Tibetan Plateau

NASA Astrophysics Data System (ADS)

Gou, Yabin; Ma, Yingzhao; Chen, Haonan; Wen, Yixin

2018-05-01

Quantitative precipitation estimation (QPE) is one of the important applications of weather radars. However, in complex terrain such as Tibetan Plateau, it is a challenging task to obtain an optimal Z-R relation due to the complex spatial and temporal variability in precipitation microphysics. This paper develops two radar QPE schemes respectively based on Reflectivity Threshold (RT) and Storm Cell Identification and Tracking (SCIT) algorithms using observations from 11 Doppler weather radars and 3264 rain gauges over the Eastern Tibetan Plateau (ETP). These two QPE methodologies are evaluated extensively using four precipitation events that are characterized by different meteorological features. Precipitation characteristics of independent storm cells associated with these four events, as well as the storm-scale differences, are investigated using short-term vertical profile of reflectivity (VPR) clusters. Evaluation results show that the SCIT-based rainfall approach performs better than the simple RT-based method for all precipitation events in terms of score comparison using validation gauge measurements as references. It is also found that the SCIT-based approach can effectively mitigate the local error of radar QPE and represent the precipitation spatiotemporal variability better than the RT-based scheme.

Beacon Hill end moraine, Boston: new explanation of an important urban feature

USGS Publications Warehouse

Kaye, Clifford A.; Coates, Donald R.

1976-01-01

The usefulness of geology to engineers is in direct proportion to how well it helps us predict the subsurface; these predictions, in turn, depend on our knowledge of the geomorphic processes that molded the terrain. The uncertainties of interpretation are particularly great in glaciated terrain because our understanding of both glacial processes and history is so incomplete, a fact well illustrated in Beacon Hill. Recent construction activities in the eastern part of the hill, until now classified as a drumlin, have shown that it is better interpreted as an end moraine formed by a Wisconsonian glacial readvance. Instead of the firm till that was anticipated as foundation material, excavations exposed a complex of sand, gravel, and clay, with only minor zones of till. The structure of these deposits strongly suggests that originally they were plates of the glacial bed that froze to the glacier and were transported englacially. Thrust faulting and other deformations are glacial structures formed within the ice in the glacier's terminal zone. In spite of the complex englacial history, these deposits lost little of their original appearance and intergranular relationships. Upon deglaciation, the frozen moraine thawed, and slumping formed complex secondary structures on the ridge's lower flanks.

Hydraulic Jumps, Waves and Other Flow Features Found by Modeling Stably-Stratified Flows in the Salt Lake Valley

NASA Astrophysics Data System (ADS)

Chen, Y.; Ludwig, F.; Street, R.

2003-12-01

The Advanced Regional Prediction System (ARPS) was used to simulate weak synoptic wind conditions with stable stratification and pronounced drainage flow at night in the vicinity of the Jordan Narrows at the south end of Salt Lake Valley. The simulations showed the flow to be quite complex with hydraulic jumps and internal waves that make it essential to use a complete treatment of the fluid dynamics. Six one-way nested grids were used to resolve the topography; they ranged from 20-km grid spacing, initialized by ETA 40-km operational analyses down to 250-m horizontal resolution and 200 vertically stretched levels to a height of 20 km, beginning with a 10-m cell at the surface. Most of the features of interest resulted from interactions with local terrain features, so that little was lost by using one-way nesting. Canyon, gap, and over-terrain flows have a large effect on mixing and vertical transport, especially in the regions where hydraulic jumps are likely. Our results also showed that the effect of spatial resolution on simulation performance is profound. The horizontal resolution must be such that the smallest features that are likely to have important impact on the flow are spanned by at least a few grid points. Thus, the 250 m minimum resolution of this study is appropriate for treating the effects of features of about 1 km or greater extent. To be consistent, the vertical cell dimension must resolve the same terrain features resolved by the horizontal grid. These simulations show that many of the interesting flow features produce observable wind and temperature gradients at or near the surface. Accordingly, some relatively simple field measurements might be made to confirm that the mixing phenomena that were simulated actually take place in the real atmosphere, which would be very valuable for planning large, expensive field campaigns. The work was supported by the Atmospheric Sciences Program, Office of Biological and Environmental Research, U.S. Department of Energy. The National Energy Research Scientific Computing Center (NERSC) provided computational time. We thank Professor Ming Xue and others at the University of Oklahoma for their help.

Sensor image prediction techniques

NASA Astrophysics Data System (ADS)

Stenger, A. J.; Stone, W. R.; Berry, L.; Murray, T. J.

1981-02-01

The preparation of prediction imagery is a complex, costly, and time consuming process. Image prediction systems which produce a detailed replica of the image area require the extensive Defense Mapping Agency data base. The purpose of this study was to analyze the use of image predictions in order to determine whether a reduced set of more compact image features contains enough information to produce acceptable navigator performance. A job analysis of the navigator's mission tasks was performed. It showed that the cognitive and perceptual tasks he performs during navigation are identical to those performed for the targeting mission function. In addition, the results of the analysis of his performance when using a particular sensor can be extended to the analysis of this mission tasks using any sensor. An experimental approach was used to determine the relationship between navigator performance and the type of amount of information in the prediction image. A number of subjects were given image predictions containing varying levels of scene detail and different image features, and then asked to identify the predicted targets in corresponding dynamic flight sequences over scenes of cultural, terrain, and mixed (both cultural and terrain) content.

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 the analysis from the Mars Science Laboratory's terminal descent sensing model. Alternate uses will also be shown for determining horizon maps and orbiter set times.

Volcanic Constructs on Ganymede and Enceladus: Topographic Evidence from Stereo Images and Photoclinometry

NASA Technical Reports Server (NTRS)

Schenk, Paul M.; Moore, Jeffrey M.

1995-01-01

The morphology of volcanic features on Ganymede differs significantly from that on the terrestrial planets. Few if any major volcanic landforms, such as thick flows or shield volcanoes, have been identified to date. Using new stereo Voyager images, we have searched Ganymede for relief-generating volcanic constructs. We observed seven major types of volcanic structures, including several not previously recognized. The oldest are broad flat-topped domes partially filling many older craters in dark terrain. Similar domes occur on Enceladus. Together with smooth dark deposits, these domes indicate that the volcanic history of the dark terrain is complex. Bright terrain covers vast areas, although the style of emplacement remains unclear. Smooth bright materials embay and flood older terrains, and may have been emplaced as low- viscosity fluids. Associated with smooth bright material are a number of scalloped-shaped, semi- enclosed scarps that cut into preexisting terrain. In planform these structures resemble terrestrial calderas. The youngest volcanic materials identified are a series of small flows that may have flooded the floor of the multiring impact structure Gilgamesh, forming a broad dome, The identification of volcanic constructs up to I km thick is the first evidence for extrusion of moderate-to-high viscosity material on Ganymede. Viscosity and yield strength estimates for these materials span several orders of magnitude, indicating that volcanic materials on Ganymede have a range of compositions and/or were extruded under a wide range of conditions and/or eruptive styles.

An Application of Multi-Criteria Shortest Path to a Customizable Hex-Map Environment

DTIC Science & Technology

2015-03-26

forces which could act as intermediate destinations or obstacles to movement through the network. This is similar to a traveling salesman problem ...118 Abstract The shortest path problem of finding the optimal path through a complex network is well-studied in the field of operations research. This...research presents an applica- tion of the shortest path problem to a customizable map with terrain features and enemy engagement risk. The PathFinder

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.

Inverted Martian Craters in Lineated Glacial Valleys, Ismenius Lacus Region, Mars

NASA Technical Reports Server (NTRS)

McConnell, B. S.; Wilt, G. L.; Gillespie, A.; Newsom, H. E.

2005-01-01

We studied small, uniquely-shaped craters found on the surface of lineated terrain in the Ismenius Lacus region of Mars. By utilizing MOC and THEMIS satellite images, we located terrain including lineations (viscous flow features), smoothing of topography, and morphologic features such as polygons and gullies, which appear to be strong evidence of preexisting ice deposits.

Terrain-Moisture Classification Using GPS Surface-Reflected Signals

NASA Technical Reports Server (NTRS)

Grant, Michael S.; Acton, Scott T.; Katzberg, Stephen J.

2006-01-01

In this study we present a novel method of land surface classification using surface-reflected GPS signals in combination with digital imagery. Two GPS-derived classification features are merged with visible image data to create terrain-moisture (TM) classes, defined here as visibly identifiable terrain or landcover classes containing a surface/soil moisture component. As compared to using surface imagery alone, classification accuracy is significantly improved for a number of visible classes when adding the GPS-based signal features. Since the strength of the reflected GPS signal is proportional to the amount of moisture in the surface, use of these GPS features provides information about the surface that is not obtainable using visible wavelengths alone. Application areas include hydrology, precision agriculture, and wetlands mapping.

Introduction Wind farms in complex terrains: an introduction.

PubMed

Alfredsson, P H; Segalini, A

2017-04-13

Wind energy is one of the fastest growing sources of sustainable energy production. As more wind turbines are coming into operation, the best locations are already becoming occupied by turbines, and wind-farm developers have to look for new and still available areas-locations that may not be ideal such as complex terrain landscapes. In these locations, turbulence and wind shear are higher, and in general wind conditions are harder to predict. Also, the modelling of the wakes behind the turbines is more complicated, which makes energy-yield estimates more uncertain than under ideal conditions. This theme issue includes 10 research papers devoted to various fluid-mechanics aspects of using wind energy in complex terrains and illustrates recent progress and future developments in this important field.This article is part of the themed issue 'Wind energy in complex terrains'. © 2017 The Author(s).

Large eddy simulation modeling of particle-laden flows in complex terrain

NASA Astrophysics Data System (ADS)

Salesky, S.; Giometto, M. G.; Chamecki, M.; Lehning, M.; Parlange, M. B.

2017-12-01

The transport, deposition, and erosion of heavy particles over complex terrain in the atmospheric boundary layer is an important process for hydrology, air quality forecasting, biology, and geomorphology. However, in situ observations can be challenging in complex terrain due to spatial heterogeneity. Furthermore, there is a need to develop numerical tools that can accurately represent the physics of these multiphase flows over complex surfaces. We present a new numerical approach to accurately model the transport and deposition of heavy particles in complex terrain using large eddy simulation (LES). Particle transport is represented through solution of the advection-diffusion equation including terms that represent gravitational settling and inertia. The particle conservation equation is discretized in a cut-cell finite volume framework in order to accurately enforce mass conservation. Simulation results will be validated with experimental data, and numerical considerations required to enforce boundary conditions at the surface will be discussed. Applications will be presented in the context of snow deposition and transport, as well as urban dispersion.

The geology of Pluto and Charon through the eyes of New Horizons

NASA Astrophysics Data System (ADS)

Moore, Jeffrey M.; McKinnon, William B.; Spencer, John R.; Howard, Alan D.; Schenk, Paul M.; Beyer, Ross A.; Nimmo, Francis; Singer, Kelsi N.; Umurhan, Orkan M.; White, Oliver L.; Stern, S. Alan; Ennico, Kimberly; Olkin, Cathy B.; Weaver, Harold A.; Young, Leslie A.; Binzel, Richard P.; Buie, Marc W.; Buratti, Bonnie J.; Cheng, Andrew F.; Cruikshank, Dale P.; Grundy, Will M.; Linscott, Ivan R.; Reitsema, Harold J.; Reuter, Dennis C.; Showalter, Mark R.; Bray, Veronica J.; Chavez, Carrie L.; Howett, Carly J. A.; Lauer, Tod R.; Lisse, Carey M.; Parker, Alex Harrison; Porter, S. B.; Robbins, Stuart J.; Runyon, Kirby; Stryk, Ted; Throop, Henry B.; Tsang, Constantine C. C.; Verbiscer, Anne J.; Zangari, Amanda M.; Chaikin, Andrew L.; Wilhelms, Don E.; Bagenal, F.; Gladstone, G. R.; Andert, T.; Andrews, J.; Banks, M.; Bauer, B.; Bauman, J.; Barnouin, O. S.; Bedini, P.; Beisser, K.; Bhaskaran, S.; Birath, E.; Bird, M.; Bogan, D. J.; Bowman, A.; Brozovic, M.; Bryan, C.; Buckley, M. R.; Bushman, S. S.; Calloway, A.; Carcich, B.; Conard, S.; Conrad, C. A.; Cook, J. C.; Custodio, O. S.; Ore, C. M. Dalle; Deboy, C.; Dischner, Z. J. B.; Dumont, P.; Earle, A. M.; Elliott, H. A.; Ercol, J.; Ernst, C. M.; Finley, T.; Flanigan, S. H.; Fountain, G.; Freeze, M. J.; Greathouse, T.; Green, J. L.; Guo, Y.; Hahn, M.; Hamilton, D. P.; Hamilton, S. A.; Hanley, J.; Harch, A.; Hart, H. M.; Hersman, C. B.; Hill, A.; Hill, M. E.; Hinson, D. P.; Holdridge, M. E.; Horanyi, M.; Jackman, C.; Jacobson, R. A.; Jennings, D. E.; Kammer, J. A.; Kang, H. K.; Kaufmann, D. E.; Kollmann, P.; Krimigis, S. M.; Kusnierkiewicz, D.; Lee, J. E.; Lindstrom, K. L.; Lunsford, A. W.; Mallder, V. A.; Martin, N.; McComas, D. J.; McNutt, R. L.; Mehoke, D.; Mehoke, T.; Melin, E. D.; Mutchler, M.; Nelson, D.; Nunez, J. I.; Ocampo, A.; Owen, W. M.; Paetzold, M.; Page, B.; Parker, J. W.; Pelletier, F.; Peterson, J.; Pinkine, N.; Piquette, M.; Protopapa, S.; Redfern, J.; Roberts, J. H.; Rogers, G.; Rose, D.; Retherford, K. D.; Ryschkewitsch, M. G.; Schindhelm, E.; Sepan, B.; Soluri, M.; Stanbridge, D.; Steffl, A. J.; Strobel, D. F.; Summers, M. E.; Szalay, J. R.; Tapley, M.; Taylor, A.; Taylor, H.; Tyler, G. L.; Versteeg, M. H.; Vincent, M.; Webbert, R.; Weidner, S.; Weigle, G. E.; Whittenburg, K.; Williams, B. G.; Williams, K.; Williams, S.; Woods, W. W.; Zirnstein, E.

2016-03-01

NASA’s New Horizons spacecraft has revealed the complex geology of Pluto and Charon. Pluto’s encounter hemisphere shows ongoing surface geological activity centered on a vast basin containing a thick layer of volatile ices that appears to be involved in convection and advection, with a crater retention age no greater than ~10 million years. Surrounding terrains show active glacial flow, apparent transport and rotation of large buoyant water-ice crustal blocks, and pitting, the latter likely caused by sublimation erosion and/or collapse. More enigmatic features include tall mounds with central depressions that are conceivably cryovolcanic and ridges with complex bladed textures. Pluto also has ancient cratered terrains up to ~4 billion years old that are extensionally faulted and extensively mantled and perhaps eroded by glacial or other processes. Charon does not appear to be currently active, but experienced major extensional tectonism and resurfacing (probably cryovolcanic) nearly 4 billion years ago. Impact crater populations on Pluto and Charon are not consistent with the steepest impactor size-frequency distributions proposed for the Kuiper belt.

The geology of Pluto and Charon through the eyes of New Horizons.

PubMed

Moore, Jeffrey M; McKinnon, William B; Spencer, John R; Howard, Alan D; Schenk, Paul M; Beyer, Ross A; Nimmo, Francis; Singer, Kelsi N; Umurhan, Orkan M; White, Oliver L; Stern, S Alan; Ennico, Kimberly; Olkin, Cathy B; Weaver, Harold A; Young, Leslie A; Binzel, Richard P; Buie, Marc W; Buratti, Bonnie J; Cheng, Andrew F; Cruikshank, Dale P; Grundy, Will M; Linscott, Ivan R; Reitsema, Harold J; Reuter, Dennis C; Showalter, Mark R; Bray, Veronica J; Chavez, Carrie L; Howett, Carly J A; Lauer, Tod R; Lisse, Carey M; Parker, Alex Harrison; Porter, S B; Robbins, Stuart J; Runyon, Kirby; Stryk, Ted; Throop, Henry B; Tsang, Constantine C C; Verbiscer, Anne J; Zangari, Amanda M; Chaikin, Andrew L; Wilhelms, Don E

2016-03-18

NASA's New Horizons spacecraft has revealed the complex geology of Pluto and Charon. Pluto's encounter hemisphere shows ongoing surface geological activity centered on a vast basin containing a thick layer of volatile ices that appears to be involved in convection and advection, with a crater retention age no greater than ~10 million years. Surrounding terrains show active glacial flow, apparent transport and rotation of large buoyant water-ice crustal blocks, and pitting, the latter likely caused by sublimation erosion and/or collapse. More enigmatic features include tall mounds with central depressions that are conceivably cryovolcanic and ridges with complex bladed textures. Pluto also has ancient cratered terrains up to ~4 billion years old that are extensionally faulted and extensively mantled and perhaps eroded by glacial or other processes. Charon does not appear to be currently active, but experienced major extensional tectonism and resurfacing (probably cryovolcanic) nearly 4 billion years ago. Impact crater populations on Pluto and Charon are not consistent with the steepest impactor size-frequency distributions proposed for the Kuiper belt. Copyright © 2016, American Association for the Advancement of Science.

The Geology of Pluto and Charon Through the Eyes of New Horizons

NASA Technical Reports Server (NTRS)

Moore, Jeffrey M.; McKinnon, William B.; Spencer, John R.; Howard, Alan D.; Schenk, Paul M.; Beyer, Ross A.; Nimmo, Francis; Singer, Kelsi N.; Umurhan, Orkan M.; White, Oliver L.;

Triton - False Color of Cantaloupe Terrain

NASA Image and Video Library

1996-09-26

Voyager violet, green, and ultraviolet images of Triton were map projected into cylindrical coordinates and combined to produce this false color terrain map. Several compositionally distinct terrain and geologic features are portrayed. At center is a gray blue unit referred to as 'cantaloupe' terrain because of its unusual topographic texture. The unit appears to predate other units to the left. Immediately adjacent to the cantaloupe terrain, is a smoother unit, represented by a reddish color, that has been dissected by a prominent fault system. This unit apparently overlies a much higher albedo material, seen farther left. A prominent angular albedo boundary separates relatively undisturbed smooth terrain from irregular patches which have been derived from breakup of the same material. Also visible at the far left are diffuse, elongated streaks, which seem to emanate from circular, often bright centered features. The parallel streaks may represent vented particulate materials blown in the same direction by winds in Triton's thin atmosphere. The Voyager Mission was conducted by JPL for NASA's Office of Space Science and Applications. http://photojournal.jpl.nasa.gov/catalog/PIA00060

Inventory and monitoring of natural vegetation and related resources in an arid environment by the use of ERTS-A imagery

NASA Technical Reports Server (NTRS)

Schrumpf, B. J. (Principal Investigator)

1972-01-01

The author has identified the following significant results. The southern Arizona test site includes vegetation representing shrub types of the Sonoran and Chihuahuan Deserts and Arizona chaparral. Also represented are grassland types of the desert grassland, juniper, and oak woodland types, and coniferous forest types. Relationships between plant species and selected terrain features are given along with the terrain feature classes used for the analyses. The purpose for determining the degree to which such relationships exist is to develop a body of knowledge to constitute the associated evidence that a photointerpreter may consult when interpreting vegetation subjects on small scale imagery. Imagery of this scale class contains little image detail which can be interpreted directly in terms of vegetation. On the other hand, some terrain features are the most salient features of that same imagery. Exploitation of those features for vegetation identification, inventory, and analysis can be accomplished only after establishing the existence of ecological relationships.

Image-based terrain modeling with thematic mapper applied to resolving the limit of Holocene Lake expansion in the Great Salt Lake Desert, Utah, part 1

NASA Technical Reports Server (NTRS)

Merola, John A.

1989-01-01

The LANDSAT Thematic Mapper (TM) scanner records reflected solar energy from the earth's surface in six wavelength regions, or bands, and one band that records emitted energy in the thermal region, giving a total of seven bands. Useful research was extracted about terrain morphometry from remote sensing measurements and this information is used in an image-based terrain model for selected coastal geomorphic features in the Great Salt Lake Desert (GSLD). Technical developments include the incorporation of Aerial Profiling of Terrain System (APTS) data in satellite image analysis, and the production and use of 3-D surface plots of TM reflectance data. Also included in the technical developments is the analysis of the ground control point spatial distribution and its affects on geometric correction, and the terrain mapping procedure; using satellite data in a way that eliminates the need to degrade the data by resampling. The most common approach for terrain mapping with multispectral scanner data includes the techniques of pattern recognition and image classification, as opposed to direct measurement of radiance for identification of terrain features. The research approach in this investigation was based on an understanding of the characteristics of reflected light resulting from the variations in moisture and geometry related to terrain as described by the physical laws of radiative transfer. The image-based terrain model provides quantitative information about the terrain morphometry based on the physical relationship between TM data, the physical character of the GSLD, and the APTS measurements.

Volcanism in Northwest Ishtar Terra, Venus

NASA Astrophysics Data System (ADS)

Gaddis, Lisa R.; Greeley, Ronald

1990-10-01

Evidence is presented for a previously undocumented volcanic complex in the highlands of NW Ishtar Terra (74 deg N, 313 deg E). The proposed valcanic center is in mountainous banded terrain thought to have been formed by regional compression. Data used include Soviet Venera 15/16 radar images and topography (Fotokarta Veneri B-4, 1987). An attempt is made to assess the place of this feature in the framework of known volcanic landforms of the Lakshmi Planum and to examine the relationships between volcanism and tectonism in this region.

Mega-geomorphology: Mars vis a vis Earth

NASA Technical Reports Server (NTRS)

Sharp, R. P.

1985-01-01

The areas of chaotic terrain, the giant chasma of the Valles Marineris region, the complex linear and circular depressions of Labyrinthus Noctis on Mars all suggest the possibility of large scale collapse of parts of the martian crust within equatorial and sub equatorial latitudes. It seems generally accepted that the above features are fossil, being perhaps, more than a billion years old. It is possible that parts of Earth's crust experienced similar episodes of large scale collapse sometime early in the evolution of the planet.

Venus tectonics - An overview of Magellan observations

NASA Technical Reports Server (NTRS)

Solomon, Sean C.; Smrekar, Suzanne E.; Bindschadler, Duane L.; Grimm, Robert E.; Kaula, William M.; Mcgill, George E.; Phillips, Roger J.; Saunders, R. S.; Schubert, Gerald; Squyres, Steven W.

1992-01-01

Magellan observations of the tectonic characteristics of highland regions on Venus are discussed with reference to competing theories for highland formation and evolution. Complex rigid terrain, or tessera, and the extent to which these elevated blocks of intensely deformed crust may be genetically related to highlands are then considered. Further, the tectonics of plains and lowland regions are examined, including deformation belts and coronae, and possible relations between such features and mantle dynamics. Implications of these observations for the global tectonics of Venus are discussed.

Nonturbulent dispersion processes in complex terrain

Treesearch

Michael A. Fosberg; Douglas G. Fox; E.A. Howard; Jack D. Cohen

1976-01-01

Mass divergence influences on plume dispersion modify classic Gaussian calculations by as much as a factor of two in complex terrain. The Gaussian plume was derived in flux form to include this process.Authors' response to comments and criticism received following this publication:

Identification of terrain cover using the optimum polarimetric classifier

NASA Technical Reports Server (NTRS)

Kong, J. A.; Swartz, A. A.; Yueh, H. A.; Novak, L. M.; Shin, R. T.

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 various terrain cover are computed from theoretical models of random medium by evaluating the 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. Analytical and Monte Carlo simulated classification errors using the fully polarimetric feature vector are compared with classification based on single features which include 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.

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.

Virtual Field Reconnaissance to enable multi-site collaboration in geoscience fieldwork in Chile.

NASA Astrophysics Data System (ADS)

Hughes, Leanne; Bateson, Luke; Ford, Jonathan; Napier, Bruce; Creixell, Christian; Contreras, Juan-Pablo; Vallette, Jane

2017-04-01

The unique challenges of geological mapping in remote terrains can make cross-organisation collaboration challenging. Cooperation between the British and Chilean Geological Surveys and the Chilean national mining company used the BGS digital Mapping Workflow and virtual field reconnaissance software (GeoVisionary) to undertake geological mapping in a complex area of Andean Geology. The international team undertook a pre-field evaluation using GeoVisionary to integrate massive volumes of data and interpret high resolution satellite imagery, terrain models and existing geological information to capture, manipulate and understand geological features and re-interpret existing maps. This digital interpretation was then taken into the field and verified using the BGS digital data capture system (SIGMA.mobile). This allowed the production of final geological interpretation and creation of a geological map. This presentation describes the digital mapping workflow used in Chile and highlights the key advantages of increased efficiency and communication to colleagues, stakeholders and funding bodies.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lundquist, K A

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.more » 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 use of flux (non-zero) boundary conditions. This anabatic flow set-up is further coupled to atmospheric physics parameterizations, which calculate surface fluxes, demonstrating that the IBM can be coupled to various land-surface parameterizations in atmospheric models. Additionally, the IB method is extended to three dimensions, using both trilinear and inverse distance weighted interpolations. Results are presented for geostrophic flow over a three-dimensional hill. It is found that while the IB method using trilinear interpolation works well for simple three-dimensional geometries, a more flexible and robust method is needed for extremely complex geometries, as found in three-dimensional urban environments. A second, more flexible, immersed boundary method is devised using inverse distance weighting, and results are compared to the first IBM approach. Additionally, the functionality to nest a domain with resolved complex geometry inside of a parent domain without resolved complex geometry is described. The new IBM approach is used to model urban terrain from Oklahoma City in a one-way nested configuration, where lateral boundary conditions are provided by the parent domain. Finally, the IB method is extended to include wall model parameterizations for rough surfaces. Two possible implementations are presented, one which uses the log law to reconstruct velocities exterior to the solid domain, and one which reconstructs shear stress at the immersed boundary, rather than velocity. These methods are tested on the three-dimensional canonical case of neutral atmospheric boundary layer flow over flat terrain.« less

Radar-derived Quantitative Precipitation Estimation in Complex Terrain over the Eastern Tibetan Plateau

NASA Astrophysics Data System (ADS)

Gou, Y.

2017-12-01

Quantitative Precipitation Estimation (QPE) is one of the important applications of weather radars. However, in complex terrain such as Tibetan Plateau, it is a challenging task to obtain an optimal Z-R relation due to the complex space time variability in precipitation microphysics. This paper develops two radar QPE schemes respectively based on Reflectivity Threshold (RT) and Storm Cell Identification and Tracking (SCIT) algorithms using observations from 11 Doppler weather radars and 3294 rain gauges over the Eastern Tibetan Plateau (ETP). These two QPE methodologies are evaluated extensively using four precipitation events that are characterized by different meteorological features. Precipitation characteristics of independent storm cells associated with these four events, as well as the storm-scale differences, are investigated using short-term vertical profiles of reflectivity clusters. Evaluation results show that the SCIT-based rainfall approach performs better than the simple RT-based method in all precipitation events in terms of score comparison using validation gauge measurements as references, with higher correlation (than 75.74%), lower mean absolute error (than 82.38%) and root-mean-square error (than 89.04%) of all the comparative frames. It is also found that the SCIT-based approach can effectively mitigate the radar QPE local error and represent precipitation spatiotemporal variability better than RT-based scheme.

Challenges in Understanding and Forecasting Winds in Complex Terrain.

NASA Astrophysics Data System (ADS)

Mann, J.; Fernando, J.; Wilczak, J. M.

2017-12-01

An overview will be given of some of the challenges in understanding and forecasting winds in complex terrain. These challenges can occur for several different reasons including 1) gaps in our understanding of fundamental physical boundary layer processes occurring in complex terrain; 2) a lack of adequate parameterizations and/or numerical schemes in NWP models; and 3) inadequate observations for initialization of NWP model forecasts. Specific phenomena that will be covered include topographic wakes/vortices, cold pools, gap flows, and mountain-valley winds, with examples taken from several air quality and wind energy related field programs in California as well as from the recent Second Wind Forecast Improvement Program (WFIP2) field campaign in the Columbia River Gorge/Basin area of Washington and Oregon States. Recent parameterization improvements discussed will include those for boundary layer turbulence, including 3D turbulence schemes, and gravity wave drag. Observational requirements for improving wind forecasting in complex terrain will be discussed, especially in the context of forecasting pressure gradient driven gap flow events.

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.

Applicability Analysis of Cloth Simulation Filtering Algorithm for Mobile LIDAR Point Cloud

NASA Astrophysics Data System (ADS)

Cai, S.; Zhang, W.; Qi, J.; Wan, P.; Shao, J.; Shen, A.

2018-04-01

Classifying the original point clouds into ground and non-ground points is a key step in LiDAR (light detection and ranging) data post-processing. Cloth simulation filtering (CSF) algorithm, which based on a physical process, has been validated to be an accurate, automatic and easy-to-use algorithm for airborne LiDAR point cloud. As a new technique of three-dimensional data collection, the mobile laser scanning (MLS) has been gradually applied in various fields, such as reconstruction of digital terrain models (DTM), 3D building modeling and forest inventory and management. Compared with airborne LiDAR point cloud, there are some different features (such as point density feature, distribution feature and complexity feature) for mobile LiDAR point cloud. Some filtering algorithms for airborne LiDAR data were directly used in mobile LiDAR point cloud, but it did not give satisfactory results. In this paper, we explore the ability of the CSF algorithm for mobile LiDAR point cloud. Three samples with different shape of the terrain are selected to test the performance of this algorithm, which respectively yields total errors of 0.44 %, 0.77 % and1.20 %. Additionally, large area dataset is also tested to further validate the effectiveness of this algorithm, and results show that it can quickly and accurately separate point clouds into ground and non-ground points. In summary, this algorithm is efficient and reliable for mobile LiDAR point cloud.

Multi-stage classification method oriented to aerial image based on low-rank recovery and multi-feature fusion sparse representation.

PubMed

Ma, Xu; Cheng, Yongmei; Hao, Shuai

2016-12-10

Automatic classification of terrain surfaces from an aerial image is essential for an autonomous unmanned aerial vehicle (UAV) landing at an unprepared site by using vision. Diverse terrain surfaces may show similar spectral properties due to the illumination and noise that easily cause poor classification performance. To address this issue, a multi-stage classification algorithm based on low-rank recovery and multi-feature fusion sparse representation is proposed. First, color moments and Gabor texture feature are extracted from training data and stacked as column vectors of a dictionary. Then we perform low-rank matrix recovery for the dictionary by using augmented Lagrange multipliers and construct a multi-stage terrain classifier. Experimental results on an aerial map database that we prepared verify the classification accuracy and robustness of the proposed method.

MECH: Algorithms and Tools for Automated Assessment of Potential Attack Locations

DTIC Science & Technology

2015-10-06

conscious and subconscious processing of the geometric structure of the local terrain, sight lines to prominent or useful terrain features, proximity...This intuition or instinct is the outcome of an unconscious or subconscious integration of available facts and impressions. Thus, in the search...adjacency. Even so, we inevitably introduce a bias between events and non-event road locations when calculating the route visibility features. 63

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.

Pluto Bladed Terrain in 3-D

NASA Image and Video Library

2016-03-31

One of the strangest landforms spotted by NASA New Horizons spacecraft when it flew past Pluto last July was the bladed terrain just east of Tombaugh Regio, the informal name given to Pluto large heart-shaped surface feature.

Fuzzy logic modeling of the resistivity parameter and topography features for aquifer assessment in hydrogeological investigation of a crystalline basement complex

NASA Astrophysics Data System (ADS)

Adabanija, M. A.; Omidiora, E. O.; Olayinka, A. I.

2008-05-01

A linguistic fuzzy logic system (LFLS)-based expert system model has been developed for the assessment of aquifers for the location of productive water boreholes in a crystalline basement complex. The model design employed a multiple input/single output (MISO) approach with geoelectrical parameters and topographic features as input variables and control crisp value as the output. The application of the method to the data acquired in Khondalitic terrain, a basement complex in Vizianagaram District, south India, shows that potential groundwater resource zones that have control output values in the range 0.3295-0.3484 have a yield greater than 6,000 liters per hour (LPH). The range 0.3174-0.3226 gives a yield less than 4,000 LPH. The validation of the control crisp value using data acquired from Oban Massif, a basement complex in southeastern Nigeria, indicates a yield less than 3,000 LPH for control output values in the range 0.2938-0.3065. This validation corroborates the ability of control output values to predict a yield, thereby vindicating the applicability of linguistic fuzzy logic system in siting productive water boreholes in a basement complex.

Map Interpretation and Terrain Analysis Course (MITAC) for Infantrymen: Illustrated Lectures

DTIC Science & Technology

1982-01-01

Factors Influencing Map Design . . . . . ..... ............ 4 Interpretation of Terrain Relief and Other Topographic Features...Institute (ARI) sponsored a project to design and develop a map interpretation and terrain analysis course (MITAC) to improve the ability of Army...helicopter pilots to navigate accurately when flying at nap-of-the-earth (NOE) altitudes (McGrath, 1975; McGrath & Foster, 1975). MITAC was designed to

A generalized adaptive mathematical morphological filter for LIDAR data

NASA Astrophysics Data System (ADS)

Cui, Zheng

Airborne Light Detection and Ranging (LIDAR) technology has become the primary method to derive high-resolution Digital Terrain Models (DTMs), which are essential for studying Earth's surface processes, such as flooding and landslides. The critical step in generating a DTM is to separate ground and non-ground measurements in a voluminous point LIDAR dataset, using a filter, because the DTM is created by interpolating ground points. As one of widely used filtering methods, the progressive morphological (PM) filter has the advantages of classifying the LIDAR data at the point level, a linear computational complexity, and preserving the geometric shapes of terrain features. The filter works well in an urban setting with a gentle slope and a mixture of vegetation and buildings. However, the PM filter often removes ground measurements incorrectly at the topographic high area, along with large sizes of non-ground objects, because it uses a constant threshold slope, resulting in "cut-off" errors. A novel cluster analysis method was developed in this study and incorporated into the PM filter to prevent the removal of the ground measurements at topographic highs. Furthermore, to obtain the optimal filtering results for an area with undulating terrain, a trend analysis method was developed to adaptively estimate the slope-related thresholds of the PM filter based on changes of topographic slopes and the characteristics of non-terrain objects. The comparison of the PM and generalized adaptive PM (GAPM) filters for selected study areas indicates that the GAPM filter preserves the most "cut-off" points removed incorrectly by the PM filter. The application of the GAPM filter to seven ISPRS benchmark datasets shows that the GAPM filter reduces the filtering error by 20% on average, compared with the method used by the popular commercial software TerraScan. The combination of the cluster method, adaptive trend analysis, and the PM filter allows users without much experience in processing LIDAR data to effectively and efficiently identify ground measurements for the complex terrains in a large LIDAR data set. The GAPM filter is highly automatic and requires little human input. Therefore, it can significantly reduce the effort of manually processing voluminous LIDAR measurements.

Surface Modification and Surface - Subsurface Exchange Processes on Europa

NASA Astrophysics Data System (ADS)

Phillips, Cynthia B.; Molaro, Jamie; Hand, Kevin P.

2017-10-01

The surface of Jupiter’s moon Europa is modified by exogenic processes such as sputtering, gardening, radiolysis, sulfur ion implantation, and thermal processing, as well as endogenic processes including tidal shaking, mass wasting, and the effects of subsurface tectonic and perhaps cryovolcanic activity. New materials are created or deposited on the surface (radiolysis, micrometeorite impacts, sulfur ion implantation, cryovolcanic plume deposits), modified in place (thermal segregation, sintering), transported either vertically or horizontally (sputtering, gardening, mass wasting, tectonic and cryovolcanic activity), or lost from Europa completely (sputtering, plumes, larger impacts). Some of these processes vary spatially, as visible in Europa’s leading-trailing hemisphere brightness asymmetry.Endogenic geologic processes also vary spatially, depending on terrain type. The surface can be classified into general landform categories that include tectonic features (ridges, bands, cracks); disrupted “chaos-type” terrain (chaos blocks, matrix, domes, pits, spots); and impact craters (simple, complex, multi-ring). The spatial distribution of these terrain types is relatively random, with some differences in apex-antiapex cratering rates and latitudinal variation in chaos vs. tectonic features.In this work, we extrapolate surface processes and rates from the top meter of the surface in conjunction with global estimates of transport and resurfacing rates. We combine near-surface modification with an estimate of surface-subsurface (and vice versa) transport rates for various geologic terrains based on an average of proposed formation mechanisms, and a spatial distribution of each landform type over Europa’s surface area.Understanding the rates and mass balance for each of these processes, as well as their spatial and temporal variability, allows us to estimate surface - subsurface exchange rates over the average surface age (~50myr) of Europa. Quantifying the timescale and volume of transported material will yield insight on whether such a process may provide fuel to sustain a biosphere in Europa’s subsurface ocean, which is relevant to searches for life by a future mission such as a potential Europa Lander.

Surface Modification and Surface - Subsurface Exchange Processes on Europa

NASA Astrophysics Data System (ADS)

Phillips, C. B.; Molaro, J.; Hand, K. P.

2017-12-01

The surface of Jupiter's moon Europa is modified by exogenic processes such as sputtering, gardening, radiolysis, sulfur ion implantation, and thermal processing, as well as endogenic processes including tidal shaking, mass wasting, and the effects of subsurface tectonic and perhaps cryovolcanic activity. New materials are created or deposited on the surface (radiolysis, micrometeorite impacts, sulfur ion implantation, cryovolcanic plume deposits), modified in place (thermal segregation, sintering), transported either vertically or horizontally (sputtering, gardening, mass wasting, tectonic and cryovolcanic activity), or lost from Europa completely (sputtering, plumes, larger impacts). Some of these processes vary spatially, as visible in Europa's leading-trailing hemisphere brightness asymmetry. Endogenic geologic processes also vary spatially, depending on terrain type. The surface can be classified into general landform categories that include tectonic features (ridges, bands, cracks); disrupted "chaos-type" terrain (chaos blocks, matrix, domes, pits, spots); and impact craters (simple, complex, multi-ring). The spatial distribution of these terrain types is relatively random, with some differences in apex-antiapex cratering rates and latitudinal variation in chaos vs. tectonic features. In this work, we extrapolate surface processes and rates from the top meter of the surface in conjunction with global estimates of transport and resurfacing rates. We combine near-surface modification with an estimate of surface-subsurface (and vice versa) transport rates for various geologic terrains based on an average of proposed formation mechanisms, and a spatial distribution of each landform type over Europa's surface area. Understanding the rates and mass balance for each of these processes, as well as their spatial and temporal variability, allows us to estimate surface - subsurface exchange rates over the average surface age ( 50myr) of Europa. Quantifying the timescale and volume of transported material will yield insight on whether such a process may provide fuel to sustain a biosphere in Europa's subsurface ocean, which is relevant to searches for life by a future mission such as a potential Europa Lander.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Churchfield, M. J.

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.

Autonomous Exploration for Gathering Increased Science

NASA Technical Reports Server (NTRS)

Bornstein, Benjamin J.; Castano, Rebecca; Estlin, Tara A.; Gaines, Daniel M.; Anderson, Robert C.; Thompson, David R.; DeGranville, Charles K.; Chien, Steve A.; Tang, Benyang; Burl, Michael C.;

Munitions related feature extraction from LIDAR data.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roberts, Barry L.

2010-06-01

The characterization of former military munitions ranges is critical in the identification of areas likely to contain residual unexploded ordnance (UXO). Although these ranges are large, often covering tens-of-thousands of acres, the actual target areas represent only a small fraction of the sites. The challenge is that many of these sites do not have records indicating locations of former target areas. The identification of target areas is critical in the characterization and remediation of these sites. The Strategic Environmental Research and Development Program (SERDP) and Environmental Security Technology Certification Program (ESTCP) of the DoD have been developing and implementing techniquesmore » for the efficient characterization of large munitions ranges. As part of this process, high-resolution LIDAR terrain data sets have been collected over several former ranges. These data sets have been shown to contain information relating to former munitions usage at these ranges, specifically terrain cratering due to high-explosives detonations. The location and relative intensity of crater features can provide information critical in reconstructing the usage history of a range, and indicate areas most likely to contain UXO. We have developed an automated procedure using an adaptation of the Circular Hough Transform for the identification of crater features in LIDAR terrain data. The Circular Hough Transform is highly adept at finding circular features (craters) in noisy terrain data sets. This technique has the ability to find features of a specific radius providing a means of filtering features based on expected scale and providing additional spatial characterization of the identified feature. This method of automated crater identification has been applied to several former munitions ranges with positive results.« less

Volcanism in Northwest Ishtar Terra, Venus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaddis, L.R.; Greeley, R.

Evidence is presented for a previously undocumented volcanic complex in the highlands of NW Ishtar Terra (74 deg N, 313 deg E). The proposed valcanic center is in mountainous banded terrain thought to have been formed by regional compression. Data used include Soviet Venera 15/16 radar images and topography (Fotokarta Veneri B-4, 1987). An attempt is made to assess the place of this feature in the framework of known volcanic landforms of the Lakshmi Planum and to examine the relationships between volcanism and tectonism in this region. 38 refs.

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...

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

USGS Publications Warehouse

,

1943-01-01

The following folio of maps and explanatory tables outlines the principal terrain features of the Chita Oblast.  Each map and table is devoted to a specialized set of problems; together they cover such subjects as terrain appreciations, rivers, surface-water and ground-water supplies, construction materials, fuels, suitability for temporary roads and airfields, mineral resources, and geology.  These maps and data were complied by the United States Geological Survey.

False Color Terrain Model of Phoenix Workspace

NASA Image and Video Library

2008-05-28

This is a terrain model of Phoenix 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 Surface Stereo Imager SSI.

Analysis of hydraulic steering system of tracked all-terrain vehicles' articulated mechanism

NASA Astrophysics Data System (ADS)

Meng, Zhongliang; Zang, Hao

2018-04-01

As for the researches on the dynamic characteristics of tracked all-terrain vehicles' articulated mechanism, the hydraulic feature of their steering system needs researching more, apart from the study on mechanical models. According to the maximum pressure required by the steering system of tracked all-terrain vehicle and the principle of the steering system, this paper conducts an analysis of the hydraulic steering system of the articulated mechanism. Based on the structure principle of the steering gear, a simulation model of the tracked all-terrain vehicle turning left is built. When building the simulation model of the steering gear, it makes a simulation analysis, taking the tracked all-terrain vehicle turning left as an example.

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.

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.

Terrain Classification of Norwegian Slab Avalanche Accidents

ERIC Educational Resources Information Center

Hallandvik, Linda; Aadland, Eivind; Vikene, Odd Lennart

2016-01-01

It is difficult to rely on snow conditions, weather, and human factors when making judgments about avalanche risk because these variables are dynamic and complex; terrain, however, is more easily observed and interpreted. Therefore, this study aimed to investigate (1) the type of terrain in which historical fatal snow avalanche accidents in Norway…

Introduction Wind farms in complex terrains: an introduction

PubMed Central

Alfredsson, P. H.; Segalini, A.

2017-01-01

Wind energy is one of the fastest growing sources of sustainable energy production. As more wind turbines are coming into operation, the best locations are already becoming occupied by turbines, and wind-farm developers have to look for new and still available areas—locations that may not be ideal such as complex terrain landscapes. In these locations, turbulence and wind shear are higher, and in general wind conditions are harder to predict. Also, the modelling of the wakes behind the turbines is more complicated, which makes energy-yield estimates more uncertain than under ideal conditions. This theme issue includes 10 research papers devoted to various fluid-mechanics aspects of using wind energy in complex terrains and illustrates recent progress and future developments in this important field. This article is part of the themed issue ‘Wind energy in complex terrains’. PMID:28265020

Analysing wind farm efficiency on complex terrains

NASA Astrophysics Data System (ADS)

Castellani, Francesco; Astolfi, Davide; Terzi, Ludovico; Schaldemose Hansen, Kurt; Sanz Rodrigo, Javier

2014-06-01

Actual performances of onshore wind farms are deeply affected both by wake interactions and terrain complexity: therefore monitoring how the efficiency varies with the wind direction is a crucial task. Polar efficiency plot is therefore a useful tool for monitoring wind farm performances. The approach deserves careful discussion for onshore wind farms, where orography and layout commonly affect performance assessment. The present work deals with three modern wind farms, owned by Sorgenia Green, located on hilly terrains with slopes from gentle to rough. Further, onshore wind farm of Nprrekffir Enge has been analysed as a reference case: its layout is similar to offshore wind farms and the efficiency is mainly driven by wakes. It is shown and justified that terrain complexity imposes a novel and more consistent way for defining polar efficiency. Dependency of efficiency on wind direction, farm layout and orography is analysed and discussed. Effects of atmospheric stability have been also investigated through MERRA reanalysis data from NASA satellites. Monin-Obukhov Length has been used to discriminate climate regimes.

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

Treesearch

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

2007-01-01

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...

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

Treesearch

F.S. Peterson; K. Lajtha

2013-01-01

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...

An interdisciplinary swat ecohydrological model to define catchment-scale hydrologic partitioning

NASA Astrophysics Data System (ADS)

Shope, C. L.; Maharjan, G. R.; Tenhunen, J.; Seo, B.; Kim, K.; Riley, J.; Arnhold, S.; Koellner, T.; Ok, Y. S.; Peiffer, S.; Kim, B.; Park, J.-H.; Huwe, B.

2013-06-01

Land use and climate change have long been implicated in modifying ecosystem services, such as water quality and water yield, biodiversity, and agricultural production. To account for future effects on ecosystem services, the integration of physical, biological, economic, and social data over several scales must be implemented to assess the effects on natural resource availability and use. Our objective is to assess the capability of the SWAT model to capture short-duration monsoonal rainfall-runoff processes in complex mountainous terrain under rapid, event-driven processes in a monsoonal environment. To accomplish this, we developed a unique quality-control gap-filling algorithm for interpolation of high frequency meteorological data. We used a novel multi-location, multi-optimization calibration technique to improve estimations of catchment-wide hydrologic partitioning. We calibrated the interdisciplinary model to a combination of statistical, hydrologic, and plant growth metrics. In addition, we used multiple locations of different drainage area, aspect, elevation, and geologic substrata distributed throughout the catchment. Results indicate scale-dependent sensitivity of hydrologic partitioning and substantial influence of engineered features. While our model accurately reproduced observed discharge variability, the addition of hydrologic and plant growth objective functions identified the importance of culverts in catchment-wide flow distribution. The results of this study provide a valuable resource to describe landscape controls and their implication on discharge, sediment transport, and nutrient loading. This study also shows the challenges of applying the SWAT model to complex terrain and extreme environments. By incorporating anthropogenic features into modeling scenarios, we can greatly enhance our understanding of the hydroecological impacts on ecosystem services.

Spacecraft studies of Phobos and Mars

NASA Technical Reports Server (NTRS)

Murray, Bruce C.

1990-01-01

Utilizing the Termoskan data set of the Phobos '88 mission we have recognized a new feature on Mars: Ejecta blanket Distinct In the THermal infrared (EDITH). Virtually all of the more than one hundred of these features discovered in the Termoskan data are located on the plains near Valles Manneris. EDITH's have a startlingly clear dependence upon terrains of Hesperian age, implying a spatial or temporal dependence on Hesperian terrains. Almost no thermally distinct ejecta blankets are associated with any of the thousands of craters within the data set that occur on the older Noachian units. EDITH's also do not appear on the portions of the younger Tharsis Amazonian units seen in the data. The Hesperian terrain dependence cannot be explained by either atmospheric or impactor variations; Noachian and Hesperian terrains must have experienced identical atmospheric and impactor conditions during Hesperian times. Thermally distinct eject a blankets therefore reflect target material differences and/or secondary modification processes. A further discussion of EIDTH's is presented.

An efficient approach for site-specific scenery prediction in surveillance imaging near Earth's surface

NASA Astrophysics Data System (ADS)

Jylhä, Juha; Marjanen, Kalle; Rantala, Mikko; Metsäpuro, Petri; Visa, Ari

2006-09-01

Surveillance camera automation and camera network development are growing areas of interest. This paper proposes a competent approach to enhance the camera surveillance with Geographic Information Systems (GIS) when the camera is located at the height of 10-1000 m. A digital elevation model (DEM), a terrain class model, and a flight obstacle register comprise exploited auxiliary information. The approach takes into account spherical shape of the Earth and realistic terrain slopes. Accordingly, considering also forests, it determines visible and shadow regions. The efficiency arises out of reduced dimensionality in the visibility computation. Image processing is aided by predicting certain advance features of visible terrain. The features include distance from the camera and the terrain or object class such as coniferous forest, field, urban site, lake, or mast. The performance of the approach is studied by comparing a photograph of Finnish forested landscape with the prediction. The predicted background is well-fitting, and potential knowledge-aid for various purposes becomes apparent.

Spacecraft studies of PHOBOS and Mars

NASA Astrophysics Data System (ADS)

Murray, Bruce C.

Utilizing the Termoskan data set of the Phobos '88 mission we have recognized a new feature on Mars: Ejecta blanket Distinct In the THermal infrared (EDITH). Virtually all of the more than one hundred of these features discovered in the Termoskan data are located on the plains near Valles Manneris. EDITH's have a startlingly clear dependence upon terrains of Hesperian age, implying a spatial or temporal dependence on Hesperian terrains. Almost no thermally distinct ejecta blankets are associated with any of the thousands of craters within the data set that occur on the older Noachian units. EDITH's also do not appear on the portions of the younger Tharsis Amazonian units seen in the data. The Hesperian terrain dependence cannot be explained by either atmospheric or impactor variations; Noachian and Hesperian terrains must have experienced identical atmospheric and impactor conditions during Hesperian times. Thermally distinct eject a blankets therefore reflect target material differences and/or secondary modification processes. A further discussion of EIDTH's is presented.

Multi-Scale Voxel Segmentation for Terrestrial Lidar Data within Marshes

NASA Astrophysics Data System (ADS)

Nguyen, C. T.; Starek, M. J.; Tissot, P.; Gibeaut, J. C.

2016-12-01

The resilience of marshes to a rising sea is dependent on their elevation response. Terrestrial laser scanning (TLS) is a detailed topographic approach for accurate, dense surface measurement with high potential for monitoring of marsh surface elevation response. The dense point cloud provides a 3D representation of the surface, which includes both terrain and non-terrain objects. Extraction of topographic information requires filtering of the data into like-groups or classes, therefore, methods must be incorporated to identify structure in the data prior to creation of an end product. A voxel representation of three-dimensional space provides quantitative visualization and analysis for pattern recognition. The objectives of this study are threefold: 1) apply a multi-scale voxel approach to effectively extract geometric features from the TLS point cloud data, 2) investigate the utility of K-means and Self Organizing Map (SOM) clustering algorithms for segmentation, and 3) utilize a variety of validity indices to measure the quality of the result. TLS data were collected at a marsh site along the central Texas Gulf Coast using a Riegl VZ 400 TLS. The site consists of both exposed and vegetated surface regions. To characterize structure of the point cloud, octree segmentation is applied to create a tree data structure of voxels containing the points. The flexibility of voxels in size and point density makes this algorithm a promising candidate to locally extract statistical and geometric features of the terrain including surface normal and curvature. The characteristics of the voxel itself such as the volume and point density are also computed and assigned to each point as are laser pulse characteristics. The features extracted from the voxelization are then used as input for clustering of the points using the K-means and SOM clustering algorithms. Optimal number of clusters are then determined based on evaluation of cluster separability criterions. Results for different combinations of the feature space vector and differences between K-means and SOM clustering will be presented. The developed method provides a novel approach for compressing TLS scene complexity in marshes, such as for vegetation biomass studies or erosion monitoring.

A framework for WRF to WRF-IBM grid nesting to enable multiscale simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wiersema, David John; Lundquist, Katherine A.; Chow, Fotini Katapodes

With advances in computational power, mesoscale models, such as the Weather Research and Forecasting (WRF) model, are often pushed to higher resolutions. As the model’s horizontal resolution is refined, the maximum resolved terrain slope will increase. Because WRF uses a terrain-following coordinate, this increase in resolved terrain slopes introduces additional grid skewness. At high resolutions and over complex terrain, this grid skewness can introduce large numerical errors that require methods, such as the immersed boundary method, to keep the model accurate and stable. Our implementation of the immersed boundary method in the WRF model, WRF-IBM, has proven effective at microscalemore » simulations over complex terrain. WRF-IBM uses a non-conforming grid that extends beneath the model’s terrain. Boundary conditions at the immersed boundary, the terrain, are enforced by introducing a body force term to the governing equations at points directly beneath the immersed boundary. Nesting between a WRF parent grid and a WRF-IBM child grid requires a new framework for initialization and forcing of the child WRF-IBM grid. This framework will enable concurrent multi-scale simulations within the WRF model, improving the accuracy of high-resolution simulations and enabling simulations across a wide range of scales.« less

Towards Camera-LIDAR Fusion-Based Terrain Modelling for Planetary Surfaces: Review and Analysis

PubMed Central

Shaukat, Affan; Blacker, Peter C.; Spiteri, Conrad; Gao, Yang

2016-01-01

In recent decades, terrain modelling and reconstruction techniques have increased research interest in precise short and long distance autonomous navigation, localisation and mapping within field robotics. One of the most challenging applications is in relation to autonomous planetary exploration using mobile robots. Rovers deployed to explore extraterrestrial surfaces are required to perceive and model the environment with little or no intervention from the ground station. Up to date, stereopsis represents the state-of-the art method and can achieve short-distance planetary surface modelling. However, future space missions will require scene reconstruction at greater distance, fidelity and feature complexity, potentially using other sensors like Light Detection And Ranging (LIDAR). LIDAR has been extensively exploited for target detection, identification, and depth estimation in terrestrial robotics, but is still under development to become a viable technology for space robotics. This paper will first review current methods for scene reconstruction and terrain modelling using cameras in planetary robotics and LIDARs in terrestrial robotics; then we will propose camera-LIDAR fusion as a feasible technique to overcome the limitations of either of these individual sensors for planetary exploration. A comprehensive analysis will be presented to demonstrate the advantages of camera-LIDAR fusion in terms of range, fidelity, accuracy and computation. PMID:27879625

Metabolic Costs of Military Load Carriage over Complex Terrain.

PubMed

Looney, David P; Santee, William R; Karis, Anthony J; Blanchard, Laurie A; Rome, Maxwell N; Carter, Alyssa J; Potter, Adam W

2018-05-31

Dismounted military operations often involve prolonged load carriage over complex terrain, which can result in excessive metabolic costs that can directly impair soldiers' performance. Although estimating these demands is a critical interest for mission planning purposes, it is unclear whether existing estimation equations developed from controlled laboratory- and field-based studies accurately account for energy costs of traveling over complex terrain. This study investigated the accuracy of the following equations for military populations when applied to data collected over complex terrain with two different levels of load carriage: American College of Sports Medicine (2002), Givoni and Goldman (1971), Jobe and White (2009), Minetti et al (2002), Pandolf et al (1977), and Santee et al (2003). Nine active duty military personnel (age 21 ± 3 yr; height 1.72 ± 0.07 m; body mass 83.4 ± 12.9 kg; VO2 max 47.8 ± 3.9 mL/kg/min) were monitored during load carriage (with loads equal to 30% and 45% of body mass) over a 10-km mixed terrain course on two separate test days. The course was divided into four 2.5-km laps of 40 segments based on distance, grade, and/or surface factors. Timing gates and radio-frequency identification cards (SportIdent; Scarborough Orienteering, Huntington Beach, CA) were used to record completion times for each course segment. Breath-by-breath measures of energy expenditure were collected using portable oxygen exchange devices (COSMED Sri., Rome, Italy) and compared model estimates. The Santee et al equation performed best, demonstrating the smallest estimation bias (-13 ± 87 W) and lowest root mean square error (99 W). Current predictive equations underestimate the metabolic cost of load carriage by military personnel over complex terrain. Applying the Santee et al correction factor to the Pandolf et al equation may be the most suitable approach for estimating metabolic demands in these circumstances. However, this work also outlines the need for improvements to these methods, new method development and validation, or the use of a multi-model approach to account for mixed terrain.

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.

Measurements of car-body lateral vibration induced by high-speed trains negotiating complex terrain sections under strong wind conditions

NASA Astrophysics Data System (ADS)

Liu, Dongrun; Lu, Zhaijun; Zhong, Mu; Cao, Tianpei; Chen, Dong; Xiong, Yupu

2018-02-01

Assessment of the vibration of high-speed trains negotiating complex sections of terrain under strong wind conditions is very important for research into the operation safety and comfort of passengers on high-speed trains. To assess the vibration of high-speed trains negotiating complex sections of terrain under strong wind conditions, we performed a field measurement when the train passes through typical sections of complex terrain along the Lanzhou-Xinjiang high-speed railway in China. We selected the lateral vibration conditions, including the roll angle and lateral displacement of car-body gravity centre through two typical representative sections (embankment-tunnel-embankment and embankment-rectangular transition-cutting) for analysis. The results show that the severe car-swaying phenomenon occurs when the high-speed train moves through the test section, and the car-body lateral vibration characteristic is related significantly to the state of the terrain and topography along the railway. The main causes for this car-swaying phenomenon may be the transitions between different windproof structures, and the greater the scale of the transition region between different windproof structures or landform changes, the more obvious the car-swaying phenomenon becomes. The lateral vibration of the car-body is relatively steady when the train is running through terrain with minor changes in topography, such as the windbreak installed on the bridge and embankment, but the tail car sways more violently than the head car. When the vehicle runs from the windbreak installed on the embankment into the tunnel (or in the opposite direction), the tail car sways more intensely than the head car, and the head car runs relatively stable in the tunnel.

KRISSY: user's guide to modeling three-dimensional wind flow in complex terrain

Treesearch

Michael A. Fosberg; Michael L. Sestak

1986-01-01

KRISSY is a computer model for generating three-dimensional wind flows in complex terrain from data that were not or perhaps cannot be collected. The model is written in FORTRAN IV This guide describes data requirements, modeling, and output from an applications viewpoint rather than that of programming or theoretical modeling. KRISSY is designed to minimize...

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.

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.

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.

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.

Virtual terrain: a security-based representation of a computer network

NASA Astrophysics Data System (ADS)

Holsopple, Jared; Yang, Shanchieh; Argauer, Brian

2008-03-01

Much research has been put forth towards detection, correlating, and prediction of cyber attacks in recent years. As this set of research progresses, there is an increasing need for contextual information of a computer network to provide an accurate situational assessment. Typical approaches adopt contextual information as needed; yet such ad hoc effort may lead to unnecessary or even conflicting features. The concept of virtual terrain is, therefore, developed and investigated in this work. Virtual terrain is a common representation of crucial information about network vulnerabilities, accessibilities, and criticalities. A virtual terrain model encompasses operating systems, firewall rules, running services, missions, user accounts, and network connectivity. It is defined as connected graphs with arc attributes defining dynamic relationships among vertices modeling network entities, such as services, users, and machines. The virtual terrain representation is designed to allow feasible development and maintenance of the model, as well as efficacy in terms of the use of the model. This paper will describe the considerations in developing the virtual terrain schema, exemplary virtual terrain models, and algorithms utilizing the virtual terrain model for situation and threat assessment.

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.

Inferring the contribution of advection to total ecosystem scalar fluxes over a tall forest in complex terrain

Treesearch

K. Novick; S. Brantley; C. Ford Miniat; J. Walker; J.M. Vose

2014-01-01

Multiple data streams from a new flux tower located in complex and heterogeneous terrain at theCoweeta Hydrologic Laboratory (North Carolina, USA) were integrated to identify periods of advectiveflow regimes. Drainage flows were expected a priori, due to the location of the measurement site at thebase of a long, gently-sloping valley. Drainage flow was confirmed by...

The influence of terrain forcing on the initiation of deep convection over Mediterranean islands

NASA Astrophysics Data System (ADS)

Barthlott, Christian; Kirshbaum, Daniel

2013-04-01

The influence of mountainous islands on the initiation of deep convection is investigated using the Consortium for Small-scale Modeling (COSMO) model. The study day is 26 August 2009 on which moist convection occurred over both the Corsica and Sardinia island in the Mediterranean Sea. Sensitivity runs with systematically modified topography are explored to evaluate the relative importance of the land-sea contrast and the terrain height for convection initiation. Whereas no island precipitation is simulated when the islands are completely removed, all simulations that represent these land surfaces develop convective precipitation. Although convection initiates progressively earlier in the day over taller islands, the precipitation rates and accumulations do not show a fixed relationship with terrain height. This is due to the competing effects of different physical processes. First, whereas the forcing for low-level ascent increases over taller islands, the boundary-layer moisture supply decreases, which diminishes the conditional instability and precipitable water. Second, whereas taller islands enhance the inland propagation speeds of sea-breeze fronts, they also mechanically block these fronts and prevent them from reaching the island interior. As a result, the island precipitation is rather insensitive to island terrain height except for one particular case in which the island precipitation increases considerably due to an optimal superposition of the sea breeze and upslope flow. These results demonstrate the complexity of interactions between sea breezes and orography and reinforce that an adequate representation of detailed topographic features is necessary to account for thermally induced wind systems that initiate deep convection.

Information measures for terrain visualization

NASA Astrophysics Data System (ADS)

Bonaventura, Xavier; Sima, Aleksandra A.; Feixas, Miquel; Buckley, Simon J.; Sbert, Mateu; Howell, John A.

2017-02-01

Many quantitative and qualitative studies in geoscience research are based on digital elevation models (DEMs) and 3D surfaces to aid understanding of natural and anthropogenically-influenced topography. As well as their quantitative uses, the visual representation of DEMs can add valuable information for identifying and interpreting topographic features. However, choice of viewpoints and rendering styles may not always be intuitive, especially when terrain data are augmented with digital image texture. In this paper, an information-theoretic framework for object understanding is applied to terrain visualization and terrain view selection. From a visibility channel between a set of viewpoints and the component polygons of a 3D terrain model, we obtain three polygonal information measures. These measures are used to visualize the information associated with each polygon of the terrain model. In order to enhance the perception of the terrain's shape, we explore the effect of combining the calculated information measures with the supplementary digital image texture. From polygonal information, we also introduce a method to select a set of representative views of the terrain model. Finally, we evaluate the behaviour of the proposed techniques using example datasets. A publicly available framework for both the visualization and the view selection of a terrain has been created in order to provide the possibility to analyse any terrain model.

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.

Retrievals of Surface Air Temperature Using Multiple Satellite Data Combinations over Complex Terrain in the Korean Peninsula

NASA Astrophysics Data System (ADS)

Jang, K.; Won, M.; Yoon, S.; Lim, J.

2016-12-01

Surface air temperature (Tair) is a fundamental factor for terrestrial environments and plays a major role in the fields of applied meteorology, climatology, and ecology. The satellite remotely sensed data offers the opportunity to estimate Tair on the earth's surface with high spatial and temporal resolutions. The Moderate Resolution Imaging Spectroradiometer (MODIS) provides effective Tair retrievals although restricted to clear sky condition. MODIS Tair over complex terrain can result in significant retrieval errors due to the retrieval height mismatch to the elevation of local weather stations. In this study, we propose the methodology to estimate Tair over complex terrain for all sky conditions using multiple satellite data fusion based on the pixel-wise regression method. The combination of synergistic information from MODIS Tair and the brightness temperature (Tb) retrievals at 37 GHz frequency from the satellite microwave sensor were used for analysis. The air temperature lapse rate was applied to estimate the near-surface Tair considering the complex terrain such as mountainous regions. The retrieval results produced from this study showed a good agreement (RMSE < 2.5 K) with weather measurements from the Korea Forest Service (KFS) for mountain regions and the Korea Meteorology Administration (KMA). The gaps in the MODIS Tair data due to cloud contamination were successfully filled using the proposed method which yielded similar accuracy as retrievals of clear sky. The results of this study indicate that the satellite data fusion can continuously produce Tair retrievals with reasonable accuracy and that the application of the temperature lapse rate can lead to improvement of the reliability over complex terrains such as the Korean Peninsula.

Inventory and monitoring of natural vegetation and related resources in an arid environment

NASA Technical Reports Server (NTRS)

Schrumpf, B. J. (Principal Investigator); Johnson, J. R.; Mouat, D. A.

1973-01-01

The author has identified the following significant results. A vegetation classification has been established for the test site (approx. 8300 sq km); 31 types are recognized. Some relationships existing among vegetation types and associated terrain features have been characterized. Terrain features can be used to discriminate vegetation types. Macrorelief interpretations on ERTS-1 imagery can be performed with greater accuracy when using high sun angle stereoscopic viewing rather than low sun angle monoscopic viewing. Some plant phenological changes are being recorded by the MSS system.

Large-Eddy Simulations of Atmospheric Flows Over Complex Terrain Using the Immersed-Boundary Method in the Weather Research and Forecasting Model

NASA Astrophysics Data System (ADS)

Ma, Yulong; Liu, Heping

2017-12-01

Atmospheric flow over complex terrain, particularly recirculation flows, greatly influences wind-turbine siting, forest-fire behaviour, and trace-gas and pollutant dispersion. However, there is a large uncertainty in the simulation of flow over complex topography, which is attributable to the type of turbulence model, the subgrid-scale (SGS) turbulence parametrization, terrain-following coordinates, and numerical errors in finite-difference methods. Here, we upgrade the large-eddy simulation module within the Weather Research and Forecasting model by incorporating the immersed-boundary method into the module to improve simulations of the flow and recirculation over complex terrain. Simulations over the Bolund Hill indicate improved mean absolute speed-up errors with respect to previous studies, as well an improved simulation of the recirculation zone behind the escarpment of the hill. With regard to the SGS parametrization, the Lagrangian-averaged scale-dependent Smagorinsky model performs better than the classic Smagorinsky model in reproducing both velocity and turbulent kinetic energy. A finer grid resolution also improves the strength of the recirculation in flow simulations, with a higher horizontal grid resolution improving simulations just behind the escarpment, and a higher vertical grid resolution improving results on the lee side of the hill. Our modelling approach has broad applications for the simulation of atmospheric flows over complex topography.

Pose and motion recovery from feature correspondences and a digital terrain map.

PubMed

Lerner, Ronen; Rivlin, Ehud; Rotstein, Héctor P

2006-09-01

A novel algorithm for pose and motion estimation using corresponding features and a Digital Terrain Map is proposed. Using a Digital Terrain (or Digital Elevation) Map (DTM/DEM) as a global reference enables the elimination of the ambiguity present in vision-based algorithms for motion recovery. As a consequence, the absolute position and orientation of a camera can be recovered with respect to the external reference frame. In order to do this, the DTM is used to formulate a constraint between corresponding features in two consecutive frames. Explicit reconstruction of the 3D world is not required. When considering a number of feature points, the resulting constraints can be solved using nonlinear optimization in terms of position, orientation, and motion. Such a procedure requires an initial guess of these parameters, which can be obtained from dead-reckoning or any other source. The feasibility of the algorithm is established through extensive experimentation. Performance is compared with a state-of-the-art alternative algorithm, which intermediately reconstructs the 3D structure and then registers it to the DTM. A clear advantage for the novel algorithm is demonstrated in variety of scenarios.

Using Agisoft Photoscan to Compare Terrestrial and Planetary Volcanic Features

NASA Astrophysics Data System (ADS)

Wagner, R. V.; Henriksen, M. R.; Manheim, M. R.; Robinson, M. S.

2018-04-01

We used Agisoft Photoscan to create three high-resolution digital terrain models (DTMs) of terrestrial volcanic features. We explore the potential for using these DTMs to better understand analogous features on the Moon and on Mars.

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.

CFD three dimensional wake analysis in complex terrain

NASA Astrophysics Data System (ADS)

Castellani, F.; Astolfi, D.; Terzi, L.

2017-11-01

Even if wind energy technology is nowadays fully developed, the use of wind energy in very complex terrain is still challenging. In particular, it is challenging to characterize the combination effects of wind ow over complex terrain and wake interactions between nearby turbines and this has a practical relevance too, for the perspective of mitigating anomalous vibrations and loads as well improving the farm efficiency. In this work, a very complex terrain site has been analyzed through a Reynolds-averaged CFD (Computational Fluid Dynamics) numerical wind field model; in the simulation the inuence of wakes has been included through the Actuator Disk (AD) approach. In particular, the upstream turbine of a cluster of 4 wind turbines having 2.3 MW of rated power is studied. The objective of this study is investigating the full three-dimensional wind field and the impact of three-dimensionality on the evolution of the waked area between nearby turbines. A post-processing method of the output of the CFD simulation is developed and this allows to estimate the wake lateral deviation and the wake width. The reliability of the numerical approach is inspired by and crosschecked through the analysis of the operational SCADA (Supervisory Control and Data Acquisition) data of the cluster of interest.

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.

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.

Geomorphic Units on Titan

NASA Astrophysics Data System (ADS)

Lopes, R. M. C.; Malaska, M. J.; Schoenfeld, A.; Birch, S. P.; Hayes, A. G., Jr.

2014-12-01

The Cassini-Huygens mission has revealed the surface of Titan in unprecedented detail. The Synthetic Aperture Radar (SAR) mode on the Cassini Titan Radar Mapper is able to penetrate clouds and haze to provide high resolution (~350 m spatial resolution at best) views of the surface geology. The instrument's other modes (altimetry, scatterometry, radiometry) also provide valuable data for interpreting the geology, as do other instruments on Cassini, in particular, the Imaging Science Subsystem (ISS) and the Visual and Infrared Mapping Spectrometer (VIMS). Continuing the initial work described in Lopes et al. (2010, Icarus, 212, 744-750), we have established the major geomorphologic unit classes on Titan using data from flybys Ta through T92 (October 2004-July 2013). We will present the global distribution of the major classes of units and, where there are direct morphological contacts, describe how these classes of units relate to each other in terms of setting and emplacement history. The classes of units are mountainous/hummocky terrains, plains, dunes, labyrinthic terrains and lakes. The oldest classes of units are the mountainous/hummocky and the labyrinthic terrains. The mountainous/hummocky terrains consist of mountain chains and isolated radar-bright terrains. The labyrinthic terrains consist of highly incised dissected plateaux with medium radar backscatter. The plains are younger than both mountainous/hummocky and labyrinthic unit classes. Dunes and lakes are the youngest unit classes on Titan; no contact is observed between the dunes and lakes but it is likely that both processes are still active. We have identified individual features such as craters, channels, and candidate cryovolcanic features. Characterization and comparison of the properties of the unit classes and the individual features with data from radiometry, ISS, and VIMS provides information on their composition and possible provenance. We can use these correlations to also infer global distribution on regions not covered by SAR. This is particularly important as SAR data will not provide complete coverage of Titan by the end of the Cassini mission.

The Geology of Titan as Revealed by Cassini

NASA Astrophysics Data System (ADS)

Lopes, Rosaly M.; Malaska, Michael; Solomonidou, Anezina; Cassini RADAR Team

2015-08-01

The Cassini-Huygens mission has revealed the surface of Titan in unprecedented detail, enabling us to discern the different geomorphic units on the surface and constrain the relative times of emplacement. We used a combined dataset of Cassini’s multiple instruments and instrument modes: Synthetic Aperture Radar (SAR-RADAR), altimetry, scatterometry, imaging (ISS) and hyperspectral imaging (VIMS) to provide information on Titan’s surface geology. Continuing the initial work described in Lopes et al. [1], we established the major geomorphologic unit classes on Titan using data from flybys Ta through T92 (October 2004-July 2013). We will present the global distribution of the major classes of units and, where there are direct morphological contacts, describe how these classes of units relate to each other in terms of setting and emplacement history. The classes of units are mountainous/hummocky terrains, plains, dunes, labyrinthic terrains and lakes. The oldest classes of units are the mountainous/hummocky and the labyrinthic terrains. The mountainous/hummocky terrains consist of mountain chains and isolated radar-bright terrains. The labyrinthic terrains consist of highly incised dissected plateaus with medium radar backscatter. The plains are younger than both mountainous/hummocky and labyrinthic unit classes. Dunes and lakes are the youngest unit classes on Titan; no contact is observed between them but it is likely that both processes are still active. We have identified individual features such as craters, channels, and candidate cryovolcanic features. Characterization and comparison of the properties of the unit classes and the individual features with data from radiometry, ISS, and VIMS provides information on their composition and possible provenance. We can use these correlations to also infer global distribution on regions not covered by SAR. This is particularly important, as SAR data will not provide complete coverage of Titan by the end of the Cassini mission.References: [1] Lopes, R.M.C., et al. Icarus, 212, 744-750, 2010.

Geomorphic Units on Titan

NASA Astrophysics Data System (ADS)

Lopes, Rosaly; Malaska, Michael; Schoenfeld, Ashley; Birch, Samuel; Hayes, Alexander; Solomonidou, Anezina; Radebaugh, Jani

2015-04-01

The Cassini-Huygens mission has revealed the surface of Titan in unprecedented detail. The Synthetic Aperture Radar (SAR) mode on the Cassini Titan Radar Mapper is able to penetrate clouds and haze to provide high resolution (~350 m spatial resolution at best) views of the surface geology. The instrument's other modes (altimetry, scatterometry, radiometry) also provide valuable data for interpreting the geology, as do other instruments on Cassini, in particular, the Imaging Science Subsystem (ISS) and the Visual and Infrared Mapping Spectrometer (VIMS). Continuing the initial work described in Lopes et al. (2010, Icarus, 212, 744-750), we have established the major geomorphologic unit classes on Titan using data from flybys Ta through T92 (October 2004-July 2013). We will present the global distribution of the major classes of units and, where there are direct morphological contacts, describe how these classes of units relate to each other in terms of setting and emplacement history. The classes of units are mountainous/hummocky terrains, plains, dunes, labyrinthic terrains and lakes. The oldest classes of units are the mountainous/hummocky and the labyrinthic terrains. The mountainous/hummocky terrains consist of mountain chains and isolated radar-bright terrains. The labyrinthic terrains consist of highly incised dissected plateaux with medium radar backscatter. The plains are younger than both mountainous/hummocky and labyrinthic unit classes. Dunes and lakes are the youngest unit classes on Titan; no contact is observed between the dunes and lakes but it is likely that both processes are still active. We have identified individual features such as craters, channels, and candidate cryovolcanic features. Characterization and comparison of the properties of the unit classes and the individual features with data from radiometry, ISS, and VIMS provides information on their composition and possible provenance. We can use these correlations to also infer global distribution on regions not covered by SAR. This is particularly important as SAR data will not provide complete coverage of Titan by the end of the Cassini mission.

Automated algorithm for mapping regions of cold-air pooling in complex terrain

NASA Astrophysics Data System (ADS)

Lundquist, Jessica D.; Pepin, Nicholas; Rochford, Caitlin

2008-11-01

In complex terrain, air in contact with the ground becomes cooled from radiative energy loss on a calm clear night and, being denser than the free atmosphere at the same elevation, sinks to valley bottoms. Cold-air pooling (CAP) occurs where this cooled air collects on the landscape. This article focuses on identifying locations on a landscape subject to considerably lower minimum temperatures than the regional average during conditions of clear skies and weak synoptic-scale winds, providing a simple automated method to map locations where cold air is likely to pool. Digital elevation models of regions of complex terrain were used to derive surfaces of local slope, curvature, and percentile elevation relative to surrounding terrain. Each pixel was classified as prone to CAP, not prone to CAP, or exhibiting no signal, based on the criterion that CAP occurs in regions with flat slopes in local depressions or valleys (negative curvature and low percentile). Along-valley changes in the topographic amplification factor (TAF) were then calculated to determine whether the cold air in the valley was likely to drain or pool. Results were checked against distributed temperature measurements in Loch Vale, Rocky Mountain National Park, Colorado; in the Eastern Pyrenees, France; and in Yosemite National Park, Sierra Nevada, California. Using CAP classification to interpolate temperatures across complex terrain resulted in improvements in root-mean-square errors compared to more basic interpolation techniques at most sites within the three areas examined, with average error reductions of up to 3°C at individual sites and about 1°C averaged over all sites in the study areas.

Turbulence structure of the near-surface boundary layer in complex terrain

NASA Astrophysics Data System (ADS)

Sfyri, Eleni; Rotach, Mathias Walter; Stiperski, Ivana; Bosveld, Fred; Lehner, Manuela; Obleitner, Friedrich

2017-04-01

Monin-Obukhov Similarity Theory (MOST) is evaluated in two cases: truly complex terrain (CT) and horizontally inhomogeneous and flat (HIF) terrain. CT data are derived from 5 measurement sites, which differ in terms of slope, orientation and surface roughness at the Inn Valley of Austria (i-Box) and HIF data come from one measurement site at the Cabauw experimental site (Netherlands). The applicability of the surface-layer, 'ideal' similarity relations is examined for both data-sets and the non-dimensional variances of temperature and humidity as a function of stability (z/L, where L is the Obukhov length) are compared for each type of terrain. Large deviations from the reference curves in case of temperature are observed in both CT and HIF, leading to the conclusion that these deviations are not due to the complex terrain but due to inappropriate near-neutral description of the reference curves. It is found here that the non-dimensional temperature variance exhibits a -1 slope in the near-neutral region, for both CT and HIF datasets. In addition, the constant-fluxes hypothesis of the MOST is evaluated at one i-Box site. It is found that only about 1% of the data show constant momentum, sensible and latent heat fluxes with height. Therefore, local scaling instead of surface layer scaling is being used in this study.

Study on the performance of the articulated mechanism of tracked all-terrain vehicle

NASA Astrophysics Data System (ADS)

Meng, Zhongliang; Zang, Hao

2018-04-01

Tracked all-terrain vehicle consists of two vehicle bodies featured by superior performance, the running system which can meet the all-terrain requirement, the unique steering system, power system and the vehicle body protection system. This paper focuses on the study of the five freely articulated steering system of crawler-type all-terrain engineering vehicle. The study on the dynamic characteristics of the articulated steering system can't do without the dynamic analysis of the whole vehicle. Therefore, it first studies the overall model of the tracked all-terrain vehicle, and then based on the critical states where the overall model is situated under different road conditions, mathematical models of the articulated mechanism are built under different operating conditions and also the load bearing condition of the articulated mechanism is deduced.

Winds, Mountains, and Wildland Fire: Improved Understanding of Coupled Atmosphere-Topography-Fire Interactions Through Large-Eddy Simulation

NASA Astrophysics Data System (ADS)

Munoz-Esparza, D.; Sauer, J.; Linn, R.

2015-12-01

Anomalous and unexpected fire behavior in complex terrain continues to result in substantial loss of property and extremely dangerous conditions for firefighting field personnel. We briefly discuss proposed hypotheses of fire interactions with atmospheric flows over complex terrain that can lead to poorly-understood and potentially catastrophic scenarios. Then, our recent results of numerical investigations via large-eddy simulation of coupled atmosphere-topography-fire phenomenology with the Los Alamos National Laboratory, HiGrad-Firetec model are presented as an example of the potential for increased understanding of these complex processes. This investigation focuses on the influence of downslope surface wind enhancement through stably stratified flow over an isolated hill, and the resulting dramatic changes in fire behavior including spread rate, and intensity. Implications with respect to counter-intuitive fire behavior and extreme fire events are discussed. This work demonstrates a tremendous opportunity to immediately create safer and more effective policy for field personnel through improved predictability of atmospheric conditions over complex terrain

Flooding of Ganymede's bright terrains by low-viscosity water-ice lavas.

PubMed

Schenk, P M; McKinnon, W B; Gwynn, D; Moore, J M

2001-03-01

Large regions of the jovian moon Ganymede have been resurfaced, but the means has been unclear. Suggestions have ranged from volcanic eruptions of liquid water or solid ice to tectonic deformation, but definitive high-resolution morphological evidence has been lacking. Here we report digital elevation models of parts of the surface of Ganymede, derived from stereo pairs combining data from the Voyager and Galileo spacecraft, which reveal bright, smooth terrains that lie at roughly constant elevations 100 to 1,000 metres below the surrounding rougher terrains. These topographic data, together with new images that show fine-scale embayment and burial of older features, indicate that the smooth terrains were formed by flooding of shallow structural troughs by low-viscosity water-ice lavas. The oldest and most deformed areas (the 'reticulate' terrains) in general have the highest relative elevations, whereas units of the most common resurfaced type--the grooved terrain--lie at elevations between those of the smooth and reticulate terrains. Bright terrain, which accounts for some two-thirds of the surface, probably results from a continuum of processes, including crustal rifting, shallow flooding and groove formation. Volcanism plays an integral role in these processes, and is consistent with partial melting of Ganymede's interior.

An Investigation of the Hypotheses for Formation of the Platy-Ridged Terrain in Elysium Planitia, Mars

NASA Astrophysics Data System (ADS)

Yue, Z.; Gou, S.; Michael, G.; Di, K.; Xie, H.; Gong, H.; Shao, Y.

2017-07-01

The origin of the platy-ridged-polygonized (PRP) terrains on Martian surface has long been debated. The terrain has generally been classified as water, pack ice, or basalt lava related flow. The crater counting results of the PRP terrains suggest they are geologically very young; therefore, they are significant in understanding the recent evolution of Mars. This work evaluated the current hypotheses through detailed analysis of the distribution and microtopographies with the High Resolution Imaging Science Experiment (HiRISE) images for the PRP terrains in Elysium Planitia, Mars. Quantitative measurements and statistics of the typical features of the PRP terrains were also made. In addition, we also found an analog site in Tarim Basin in Xinjiang, China. Our results suggest that mud flow is responsible for the formation of the PRP terrains on the Mars surface, although the hypothesis of low-viscosity basalt lava floods cannot be completely excluded. This finding implies that a regional environment suitable for liquid water may have existed in recent geologic time, which has great importance for future Mars scientific exploration.

Mapping snow depth in complex alpine terrain with close range aerial imagery - estimating the spatial uncertainties of repeat autonomous aerial surveys over an active rock glacier

NASA Astrophysics Data System (ADS)

Goetz, Jason; Marcer, Marco; Bodin, Xavier; Brenning, Alexander

2017-04-01

Snow depth mapping in open areas using close range aerial imagery is just one of the many cases where developments in structure-from-motion and multi-view-stereo (SfM-MVS) 3D reconstruction techniques have been applied for geosciences - and with good reason. Our ability to increase the spatial resolution and frequency of observations may allow us to improve our understanding of how snow depth distribution varies through space and time. However, to ensure accurate snow depth observations from close range sensing we must adequately characterize the uncertainty related to our measurement techniques. In this study, we explore the spatial uncertainties of snow elevation models for estimation of snow depth in a complex alpine terrain from close range aerial imagery. We accomplish this by conducting repeat autonomous aerial surveys over a snow-covered active-rock glacier located in the French Alps. The imagery obtained from each flight of an unmanned aerial vehicle (UAV) is used to create an individual digital elevation model (DEM) of the snow surface. As result, we obtain multiple DEMs of the snow surface for the same site. These DEMs are obtained from processing the imagery with the photogrammetry software Agisoft Photoscan. The elevation models are also georeferenced within Photoscan using the geotagged imagery from an onboard GNSS in combination with ground targets placed around the rock glacier, which have been surveyed with highly accurate RTK-GNSS equipment. The random error associated with multi-temporal DEMs of the snow surface is estimated from the repeat aerial survey data. The multiple flights are designed to follow the same flight path and altitude above the ground to simulate the optimal conditions of repeat survey of the site, and thus try to estimate the maximum precision associated with our snow-elevation measurement technique. The bias of the DEMs is assessed with RTK-GNSS survey observations of the snow surface elevation of the area on and surrounding the rock glacier. Additionally, one of the challenges with processing snow cover imagery with SfM-MVS is dealing with the general homogeneity of the surface, which makes is difficult for automated-feature detection algorithms to identify key features for point matching. This challenge depends on the snow cover surface conditions, such as scale, lighting conditions (high vs. low contrast), and availability of snow-free features within a scene, among others. We attempt to explore this aspect by spatial modelling the factors influencing the precision and bias of the DEMs from image, flight, and terrain attributes.

Real-Time Integrity Monitoring of Stored Geo-Spatial Data Using Forward-Looking Remote Sensing Technology

NASA Technical Reports Server (NTRS)

Young, Steven D.; Harrah, Steven D.; deHaag, Maarten Uijt

2002-01-01

Terrain Awareness and Warning Systems (TAWS) and Synthetic Vision Systems (SVS) provide pilots with displays of stored geo-spatial data (e.g. terrain, obstacles, and/or features). As comprehensive validation is impractical, these databases typically have no quantifiable level of integrity. This lack of a quantifiable integrity level is one of the constraints that has limited certification and operational approval of TAWS/SVS to "advisory-only" systems for civil aviation. Previous work demonstrated the feasibility of using a real-time monitor to bound database integrity by using downward-looking remote sensing technology (i.e. radar altimeters). This paper describes an extension of the integrity monitor concept to include a forward-looking sensor to cover additional classes of terrain database faults and to reduce the exposure time associated with integrity threats. An operational concept is presented that combines established feature extraction techniques with a statistical assessment of similarity measures between the sensed and stored features using principles from classical detection theory. Finally, an implementation is presented that uses existing commercial-off-the-shelf weather radar sensor technology.

Cloud and convection frequencies over the southeast United States as related to small-scale geographic features

NASA Technical Reports Server (NTRS)

Gibson, Harold M.; Vonder Haar, Thomas H.

1990-01-01

Based on relatively high spatial and temporal resolution satelite data collected at 0700 CST and at each hour from 1000 CST to 1700 CST during the summer of 1986, cloud and convection variations over the area from Mississippi east to Georgia and from the Gulf of Mexico north to Tennessee are discussed. The data analyses show an average maximum cloud frequency over the land areas at 1400 local time and a maximum of deep convection one hour later. Both cloudiness and deep convection are found to be at a maximum during the nocturnal hours over the Gulf of Mexico. Cloud frequency shows a strong relationship to small terrain features. Small fresh water bodies have cloud minima relative to the surroundings in the afternoon hours. Higher, steep terrain shows cloud maxima and the adjacent lower terrain exhibits afternoon cloud minima due to a divergence of mountain breeze caused by the valley.

Body shape helps legged robots climb and turn in complex 3-D terrains

NASA Astrophysics Data System (ADS)

Han, Yuanfeng; Wang, Zheliang; Li, Chen

Analogous to streamlined shapes that reduce drag in fluids, insects' ellipsoid-like rounded body shapes were recently discovered to be ``terradynamically streamlined'' and enhance locomotion in cluttered terrain by facilitating body rolling. Here, we hypothesize that there exist more terradynamic shapes that facilitate other modes of locomotion like climbing and turning in complex 3-D terrains by facilitating body pitching and yawing. To test our hypothesis, we modified the body shape of a legged robot by adding an elliptical and a rectangular shell and tested how it negotiated with circular and square vertical pillars. With a rectangular shell the robot always pitched against square pillars in an attempt to climb, whereas with an elliptical shell it always yawed and turned away from circular pillars given a small initial lateral displacement. Square / circular pillars facilitated pitching / yawing, respectively. To begin to reveal the contact physics, we developed a locomotion energy landscape model. Our model revealed that potential energy barriers to transition from pitching to yawing are high for angular locomotor and obstacle shapes (rectangular / square) but vanish for rounded shapes (elliptical / circular). Our study supports the plausibility of locomotion energy landscapes for understanding the rich locomotor transitions in complex 3-D terrains.

PLUME DISPERSION IN STABLY STRATIFIED FLOWS OVER COMPLEX TERRAIN, PHASE 2

EPA Science Inventory

Laboratory experiments were conducted in a stratified towing tank to investigate plume dispersion in stably stratified flows. First, plume dispersion over an idealized terrain model with a simulated elevated inversion in the atmosphere was investigated. These results were compare...

Martian Glaciers and Brain Terrain

NASA Image and Video Library

2013-09-18

This image from NASA Mars Reconnaissance Orbiter shows one of these icy lobate features wrapping around a small hill. Many lobate features are now known to be almost pure ice, like glaciers on the Earth.

Mars Exploration Rovers Entry, Descent, and Landing Trajectory Analysis

NASA Technical Reports Server (NTRS)

Desai, Prasun N.; Knocke, Philip C.

2007-01-01

In this study we present a novel method of land surface classification using surface-reflected GPS signals in combination with digital imagery. Two GPS-derived classification features are merged with visible image data to create terrain-moisture (TM) classes, defined here as visibly identifiable terrain or landcover classes containing a surface/soil moisture component. As compared to using surface imagery alone, classification accuracy is significantly improved for a number of visible classes when adding the GPS-based signal features. Since the strength of the reflected GPS signal is proportional to the amount of moisture in the surface, use of these GPS features provides information about the surface that is not obtainable using visible wavelengths alone. Application areas include hydrology, precision agriculture, and wetlands mapping.

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.

Wind Doesn't Just Stop at the Earth's Surface

NASA Astrophysics Data System (ADS)

Clifton, A. J.

2017-12-01

Wind turbines are increasingly being installed in complex terrain such as the pre-Alpine regions of Germany, Austria, and other European Alpine regions, mountainous regions across USA and Canada, and many other parts of the world. In these areas, the system of the atmosphere, terrain, geology, people, and power system has is deeply interconnected but couplings are not completely known. This leads to challenging development conditions, increased cost of energy compared to flat terrain, and sometimes to tensions between different stakeholders. In this presentation, an overview of the wind energy system will be presented, and the challenges of developing wind energy in complex terrain will be highlighted. Results from several recent measurement campaigns and associated modelling carried out by members of WindForS will be used as examples. WindForS is a southern Germany-based research consortium of more than 20 groups at higher education and research institutes, with strong links to government and industry. Finally, the new WindForS wind energy research facility in complex terrain will be introduced. The new test site will be located in the hilly, forested terrain of the Swabian Alps between Stuttgart and Germany, and will consist of two wind turbines with four meteorological towers. The test site will be used for accompanying ecological research and will also have mobile eddy covariance measurement stations as well as bird and bat monitoring systems. Seismic and noise monitoring systems are also planned. The large number of auxiliary measurements at this facility are intended to allow the complete atmosphere-wind turbine-environment-people system to be characterized. A major focus of the presentation will be on opportunities for interdisciplinary collaboration between the atmospheric science and geosciences communities and other stakeholders.

Small-scale martian polygonal terrain: Implications for liquid surface water

USGS Publications Warehouse

Seibert, N.M.; Kargel, J.S.

2001-01-01

Images from the Mars Orbiter Camera (MOC) through August 1999 were analyzed for the global distribution of small-scale polygonal terrain not clearly resolved in Viking Orbiter imagery. With very few exceptions, small-scale polygonal terrain occurs at middle to high latitudes of the northern and southern hemisphere in Hesperian-age geologic units. The largest concentration of this terrain occurs in the Utopia basin in close association with scalloped depressions (interpreted as thermokarst) and appears to represent an Amazonia event. The morphology and occurence of small polygonal terrain suggest they are either mud desiccation cracks or ice-wedge polygons. Because the small-scale polygons in Utopia and Argyre Planitiae are associated with other cold-climate permafrost or glacial features, an ice-wedge model is preferred for these areas. Both cracking mechanisms work most effectively in water- or ice-rich finegrained material and may imply the seasonal or episodic existence of liquid water at the surface.

ARC-1979-AC79-7095

NASA Image and Video Library

1979-07-11

Range : 312, 000 kilometers (195,000 miles) This photo of Ganymede (Ice Giant) was taken from Voyager 2 and shows features down to about 5 to 6 kilometers across. Different types of terrain common on Ganymede's surface are visible. 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 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 flatteded by glacier-like flows.

Transferability of a Three-Dimensional Air Quality Model between Two Different Sites in Complex Terrain.

NASA Astrophysics Data System (ADS)

Lange, Rolf

1989-07-01

The three-dimensional, diagnostic, particle-in-cell transport and diffusion model MATHEW/ADPIC is used to test its transferability from one site in complex terrain to another with different characteristics, under stable nighttime drainage flow conditions. The two sites were subject to extensive drainage flow tracer experiments under the multilaboratory Atmospheric Studies in Complex Terrain (ASCOT) program: the first being a valley in the Geysers geothermal region of northern California, and the second a canyon in western Colorado. The domain in each case is approximately 10 × 10 km. The 1980 Geysers model evaluation is only quoted. The 1984 Brush Creek model evaluation is described in detail.Results from comparing computed with measured concentrations from a variety of tracer releases indicate that 52% of the 4531 samples from five experiments in Brush Creek and 50% of the 831 samples from four experiments in the Geysers agreed within a factor of 5. When an angular 10° uncertainty, consistent with anemometer reliability limits in complex terrain, was allowed to be applied to the model results, model performance improved such that 78% of samples compared within a factor of 5 for Brush Creek and 77% for the Geysers. Looking at the range of other factors of concentration ratios, results indicate that the model is satisfactorily transferable without tuning it to a specific site.

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.

Detecting seasonal landslide movement within the Cascade landslide complex (Washington) using time-series SAR imagery

USGS Publications Warehouse

Hu, Xie; Wang, Teng; Pierson, Thomas C.; Lu, Zhong; Kim, Jin-Woo; Cecere, Thomas H.

2016-01-01

Detection of slow or limited landslide movement within broad areas of forested terrain has long been problematic, particularly for the Cascade landslide complex (Washington) located along the Columbia River Gorge. Although parts of the landslide complex have been found reactivated in recent years, the timing and magnitude of motion have not been systematically monitored or interpreted. Here we apply novel time-series strategies to study the spatial distribution and temporal behavior of the landslide movement between 2007 and 2011 using InSAR images from two overlapping L-band ALOS PALSAR-1 satellite tracks. Our results show that the reactivated part has moved approximately 700 mm downslope during the 4-year observation period, while other parts of the landslide complex have generally remained stable. However, we also detect about 300 mm of seasonal downslope creep in a terrain block upslope of the Cascade landslide complex—terrain previously thought to be stable. The temporal oscillation of the seasonal movement can be correlated with precipitation, implying that seasonal movement here is hydrology-driven. The seasonal movement also has a frequency similar to GPS-derived regional ground oscillations due to mass loading by stored rainfall and subsequent rebound but with much smaller magnitude, suggesting different hydrological loading effects. From the time-series amplitude information on terrain upslope of the headscarp, we also re-evaluate the incipient motion related to the 2008 Greenleaf Basin rock avalanche, not previously recognized by traditional SAR/InSAR methods. The approach used in this study can be used to identify active landslides in forested terrain, to track the seasonal movement of landslides, and to identify previously unknown landslide hazards.

Miranda Geologic History Variety of Terrain

NASA Image and Video Library

1996-01-29

Miranda reveals a complex geologic history in this view, acquired by NASA's Voyager 2 on Jan. 24, 1986, around its close approach to the Uranian moon. At least three terrain types of different age and geologic style are evident. http://photojournal.jpl.nasa.gov/catalog/PIA00141

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.

Generating Enhanced Natural Environments and Terrain for Interactive Combat Simulations (GENETICS)

DTIC Science & Technology

2005-09-01

split to avoid T-junctions ........................................................................52 Figure 2-23 Longest edge bisection...database. This feature allows trainers the flexibility to use the same terrain repeatedly or use a new one each time, forcing trainees to avoid ...model are favored to create a good surface approximation. Cracks are avoided by projecting primitives and their respective textures onto multiple

The importance of topographic corrections on magnetotelluric response data from rugged regions of Anatolia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guerer, A.; Ilkisik, O.M.

1997-01-01

Topographic irregularities cause some distortions of magnetotelluric (MT) fields. In the vicinity of a topographic feature, the TM-mode distortion increases with the height and inclination of the slope. It is well-known that TM-mode topographic effects are much greater than TE-mode distortions. The authors have made a study of MT anomalies in TM-mode due to two-dimensional topography. In order to reduce these effects, the distortion tensor stripping technique was used. After corrections, the resulting data can be interpreted as if they were obtained over a flat surface and depend only on the subsurface structure. However, this technique sometimes causes some geometricalmore » distortions of the real subsurface structure. One of the aims is to overcome this failure. The authors have modified the correction coefficients by considering the actual one-dimensional geology. Model studies showed that this approach is especially useful in removing the terrain effects on complex 2D subsurface structures. The other purpose of this study is to emphasize the importance of a proper terrain correction for data from sites having mountainous topography over complex geology, e.g., strike-slip faults, suture zones and rift valleys. Some examples of MT data sets collected from the North Anatolian Fault Zone and from the thrust regions of the Western Taurides will be presented.« less

3-D inversion of complex magnetotelluric data from an Archean-Proterozoic terrain in northeastern São Francisco Craton, Brazil

NASA Astrophysics Data System (ADS)

Bologna, Mauricio S.; Egbert, Gary D.; Padilha, Antonio L.; Pádua, Marcelo B.; Vitorello, Ícaro

2017-09-01

We present a magnetotelluric (MT) study in the northeastern part of the São Francisco Craton that encompasses an Archean-Proterozoic terrain, the Serrinha Block, breached by a rift basin developed mostly in Early Cretaceous times during the opening of the South Atlantic Ocean. Even though the MT sites are regularly spaced, the profiles have different orientations from one another, making the data distribution over the area highly uneven and therefore non-ideal for 3-D modeling. However, the data set is very complex, with dimensionality analysis indicating prevalence of 3-D geoelectric structure. Results from 3-D inversion are evaluated for robustness and potentiality for yielding tectonic information. At upper crustal depths, the resulting 3-D model is coherent with surface geology, whereas at mid and lower crustal depths more cryptic structures are revealed, likely of Palaeoproterozoic age. The most striking features in the model are several strong (∼1 Ωṡm) crustal conductors beneath the central part of the Serrinha Block, which we attribute to a Palaeoproterozoic oceanic plate subduction and arc-continent collision event involving the Rio Itapicuru Greenstone Belt and the basement of the Serrinha Block. The west-dipping geometry of these conductors provides a constraint on subduction polarity and gives support to tectonic evolutionary models proposing that the Rio Itapicuru Belt was formed in an island arc environment.

Sakhalin Island terrain intelligence

USGS Publications Warehouse

,

1943-01-01

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

Three-dimensional visualization of geographical terrain data using temporal parallax difference induction

NASA Astrophysics Data System (ADS)

Mayhew, Christopher A.; Mayhew, Craig M.

2009-02-01

Vision III Imaging, Inc. (the Company) has developed Parallax Image Display (PIDTM) software tools to critically align and display aerial images with parallax differences. Terrain features are rendered obvious to the viewer when critically aligned images are presented alternately at 4.3 Hz. The recent inclusion of digital elevation models in geographic data browsers now allows true three-dimensional parallax to be acquired from virtual globe programs like Google Earth. The authors have successfully developed PID methods and code that allow three-dimensional geographical terrain data to be visualized using temporal parallax differences.

Recent developments and assessment of a three-dimensional PBL parameterization for improved wind forecasting over complex terrain

NASA Astrophysics Data System (ADS)

Kosovic, B.; Jimenez, P. A.; Haupt, S. E.; Martilli, A.; Olson, J.; Bao, J. W.

2017-12-01

At present, the planetary boundary layer (PBL) parameterizations available in most numerical weather prediction (NWP) models are one-dimensional. One-dimensional parameterizations are based on the assumption of horizontal homogeneity. This homogeneity assumption is appropriate for grid cell sizes greater than 10 km. However, for mesoscale simulations of flows in complex terrain with grid cell sizes below 1 km, the assumption of horizontal homogeneity is violated. Applying a one-dimensional PBL parameterization to high-resolution mesoscale simulations in complex terrain could result in significant error. For high-resolution mesoscale simulations of flows in complex terrain, we have therefore developed and implemented a three-dimensional (3D) PBL parameterization in the Weather Research and Forecasting (WRF) model. The implementation of the 3D PBL scheme is based on the developments outlined by Mellor and Yamada (1974, 1982). Our implementation in the Weather Research and Forecasting (WRF) model uses a pure algebraic model (level 2) to diagnose the turbulent fluxes. To evaluate the performance of the 3D PBL model, we use observations from the Wind Forecast Improvement Project 2 (WFIP2). The WFIP2 field study took place in the Columbia River Gorge area from 2015-2017. We focus on selected cases when physical phenomena of significance for wind energy applications such as mountain waves, topographic wakes, and gap flows were observed. Our assessment of the 3D PBL parameterization also considers a large-eddy simulation (LES). We carried out a nested LES with grid cell sizes of 30 m and 10 m covering a large fraction of the WFIP2 study area. Both LES domains were discretized using 6000 x 3000 x 200 grid cells in zonal, meridional, and vertical direction, respectively. The LES results are used to assess the relative magnitude of horizontal gradients of turbulent stresses and fluxes in comparison to vertical gradients. The presentation will highlight the advantages of the 3D PBL scheme in regions of complex terrain.

Titan's surface from the Cassini RADAR radiometry data during SAR mode

USGS Publications Warehouse

Paganelli, F.; Janssen, M.A.; Lopes, R.M.; Stofan, E.; Wall, S.D.; Lorenz, R.D.; Lunine, J.I.; Kirk, R.L.; Roth, L.; Elachi, C.

2008-01-01

We present initial results on the calibration and interpretation of the high-resolution radiometry data acquired during the Synthetic Aperture Radar (SAR) mode (SAR-radiometry) of the Cassini Radar Mapper during its first five flybys of Saturn's moon Titan. We construct maps of the brightness temperature at the 2-cm wavelength coincident with SAR swath imaging. A preliminary radiometry calibration shows that brightness temperature in these maps varies from 64 to 89 K. Surface features and physical properties derived from the SAR-radiometry maps and SAR imaging are strongly correlated; in general, we find that surface features with high radar reflectivity are associated with radiometrically cold regions, while surface features with low radar reflectivity correlate with radiometrically warm regions. We examined scatterplots of the normalized radar cross-section ??0 versus brightness temperature, outlining signatures that characterize various terrains and surface features. The results indicate that volume scattering is important in many areas of Titan's surface, particularly Xanadu, while other areas exhibit complex brightness temperature variations consistent with variable slopes or surface material and compositional properties. ?? 2007.

A New DEM Generalization Method Based on Watershed and Tree Structure

PubMed Central

Chen, Yonggang; Ma, Tianwu; Chen, Xiaoyin; Chen, Zhende; Yang, Chunju; Lin, Chenzhi; Shan, Ligang

2016-01-01

The DEM generalization is the basis of multi-dimensional observation, the basis of expressing and analyzing the terrain. DEM is also the core of building the Multi-Scale Geographic Database. Thus, many researchers have studied both the theory and the method of DEM generalization. This paper proposed a new method of generalizing terrain, which extracts feature points based on the tree model construction which considering the nested relationship of watershed characteristics. The paper used the 5 m resolution DEM of the Jiuyuan gully watersheds in the Loess Plateau as the original data and extracted the feature points in every single watershed to reconstruct the DEM. The paper has achieved generalization from 1:10000 DEM to 1:50000 DEM by computing the best threshold. The best threshold is 0.06. In the last part of the paper, the height accuracy of the generalized DEM is analyzed by comparing it with some other classic methods, such as aggregation, resample, and VIP based on the original 1:50000 DEM. The outcome shows that the method performed well. The method can choose the best threshold according to the target generalization scale to decide the density of the feature points in the watershed. Meanwhile, this method can reserve the skeleton of the terrain, which can meet the needs of different levels of generalization. Additionally, through overlapped contour contrast, elevation statistical parameters and slope and aspect analysis, we found out that the W8D algorithm performed well and effectively in terrain representation. PMID:27517296

Using Topographic Engineering to Achieve Dominance in Urban and Complex Terrain

DTIC Science & Technology

2005-03-01

Information dominance and dominant maneuver are harder to achieve in urban and complex terrain, but there are measures we can take to give our soldiers important advantages. Engineer solutions include physical measures to interdict threat forces, such as countermine operations and emplacement of barriers, as well as command and control (C2) measures that can enhance our information dominance . This article focuses on how the topographic engineering component of information dominance helps achieve dominant maneuver in urban and

Atmospheric Flux Computations in Complex Terrain

NASA Technical Reports Server (NTRS)

Smith, Paul L.; Kopp, Fred J.; Orville, Harold D.

2000-01-01

The greatest challenges in applying atmospheric water budget expressions are in determining the divergence and evapotranspiration terms. The evapotranspiration problem is ubiquitous, and critical issues of spatial and temporal resolution commonly arise in establishing the divergence term. In complex terrain, further difficulties crop up in using typical data on atmospheric profiles of water vapor and wind to estimate the divergence term. Those difficulties are the subject of this paper; considerations related to topographic variations both along and normal to the flow direction are treated.

Classification of Informal Settlements Through the Integration of 2d and 3d Features Extracted from Uav Data

NASA Astrophysics Data System (ADS)

Gevaert, C. M.; Persello, C.; Sliuzas, R.; Vosselman, G.

2016-06-01

Unmanned Aerial Vehicles (UAVs) are capable of providing very high resolution and up-to-date information to support informal settlement upgrading projects. In order to provide accurate basemaps, urban scene understanding through the identification and classification of buildings and terrain is imperative. However, common characteristics of informal settlements such as small, irregular buildings with heterogeneous roof material and large presence of clutter challenge state-of-the-art algorithms. Especially the dense buildings and steeply sloped terrain cause difficulties in identifying elevated objects. This work investigates how 2D radiometric and textural features, 2.5D topographic features, and 3D geometric features obtained from UAV imagery can be integrated to obtain a high classification accuracy in challenging classification problems for the analysis of informal settlements. It compares the utility of pixel-based and segment-based features obtained from an orthomosaic and DSM with point-based and segment-based features extracted from the point cloud to classify an unplanned settlement in Kigali, Rwanda. Findings show that the integration of 2D and 3D features leads to higher classification accuracies.

Investigation of the Representation of OLEs and Terrain Effects Within the Coastal Zone in the EDMF Parameterization Scheme: An Airborne Doppler Wind Lidar Perspective

DTIC Science & Technology

2013-10-07

OLEs and Terrain Effects Within the Coastal Zone in the EDMF Parameterization Scheme: An Airborne Doppler Wind Lidar Perspective Annual Report Under...UPP related investigations that will be carried out in Year 3. RELATED PROJECTS ONR contract to study the utilization of Doppler wind lidar (DWL...MATERHORN2012) Paper presented at the Coherent Laser Radar Conference, June 2013 Airborne DWL investigations of flow over complex terrain (MATERHORN

High Accuracy 3D Processing of Satellite Imagery

NASA Technical Reports Server (NTRS)

Gruen, A.; Zhang, L.; Kocaman, S.

2007-01-01

Automatic DSM/DTM generation reproduces not only general features, but also detailed features of the terrain relief. Height accuracy of around 1 pixel in cooperative terrain. RMSE values of 1.3-1.5 m (1.0-2.0 pixels) for IKONOS and RMSE values of 2.9-4.6 m (0.5-1.0 pixels) for SPOT5 HRS. For 3D city modeling, the manual and semi-automatic feature extraction capability of SAT-PP provides a good basis. The tools of SAT-PP allowed the stereo-measurements of points on the roofs in order to generate a 3D city model with CCM The results show that building models with main roof structures can be successfully extracted by HRSI. As expected, with Quickbird more details are visible.

The geomorphology of Rhea - Implications for geologic history and surface processes

NASA Technical Reports Server (NTRS)

Moore, J. M.; Horner, V. M.; Greeley, R.

1985-01-01

Morphological analyses of landforms on Rhea are used to define three physiographic provinces: cratered terrain 1 undifferentiated; cratered terrain 1 lineated; and cratered terrain 2. The important statigraphic relationships between the different provinces are examined with respect to major impact basins and tectonic features. It is shown that the formation of multiringed basins may have caused, or at least controlled the locations of major resurfacing and mantling events. The diameters of the central peaks relative to the impact crater diameters are found to be significantly larger than those within the craters of the moon or Mercury. Both cratered and noncrater lineaments have regional orientations which do not fit current global or regional stress models. On the basis of the morphological analysis, a chronological order is established for the origin of the three provinces: the cratered terrain 1 province was formed first; and cratered terrain 1 lineated and cratered terrain 2 were formed second, and last, respectively. It is shown that the chronological order is generally consistent with current theoretical models of the evolution of Rhea.

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 maintainance of mesoscale internal wave phenomena. Based upon these findings, FY93 plans are discussed. A review of linear theory and theoretical modeling of a geostrophic zonal wind anomaly is included.

Venus - Lakshmi Planum

NASA Technical Reports Server (NTRS)

1990-01-01

This image is a full-resolution mosaic of several Magellan images and is centered at 61 degrees north latitude and 341 degrees east longitude. The image is 250 kilometers wide (150 miles). The radar smooth region in the northern part of the image is Lakshmi Planum, a high plateau region roughly 3.5 kilometers (2.2 miles) above the mean planetary radius. Lakshmi Planum is ringed by intensely deformed terrain, some of which is shown in the southern portion of the image and is called Clotho Tessera. The 64-kilometer (40 mile) diameter circular feature in the image is a depression called Siddons and may be a volcanic caldera. This view is supported by the collapsed lava tubes surrounding the feature. By carefully studying this and other surrounding images scientists hope to discover what tectonic and volcanic processes formed this complex region. The solid black parts of the image represent data gaps that may be filled in by the Magellan extended mission.

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

PubMed

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

2014-05-01

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

Titan's surface from Cassini RADAR SAR and high resolution radiometry data of the first five flybys

USGS Publications Warehouse

Paganelli, F.; Janssen, M.A.; Stiles, B.; West, R.; Lorenz, R.D.; Lunine, J.I.; Wall, S.D.; Callahan, P.; Lopes, R.M.; Stofan, E.; Kirk, R.L.; Johnson, W.T.K.; Roth, L.; Elachi, C.; ,

2007-01-01

The first five Titan flybys with Cassini's Synthetic Aperture RADAR (SAR) and radiometer are examined with emphasis on the calibration and interpretation of the high-resolution radiometry data acquired during the SAR mode (SAR-radiometry). Maps of the 2-cm wavelength brightness temperature are obtained coincident with the SAR swath imaging, with spatial resolution approaching 6 km. A preliminary calibration shows that brightness temperature in these maps varies from 64 to 89 K. Surface features and physical properties derived from the SAR-radiometry maps and SAR imaging are strongly correlated; in general, we find that surface features with high radar reflectivity are associated with radiometrically cold regions, while surface features with low radar reflectivity correlate with radiometrically warm regions. We examined scatterplots of the normalized radar cross-section ??0 versus brightness temperature, finding differing signatures that characterize various terrains and surface features. Implications for the physical and compositional properties of these features are discussed. The results indicate that volume scattering is important in many areas of Titan's surface, particularly Xanadu, while other areas exhibit complex brightness temperature variations consistent with variable slopes or surface material and compositional properties. ?? 2007 Elsevier Inc.

Improving high impact weather and climate prediction for societal resilience in Subtropical South America: Proyecto RELAMPAGO-CACTI

NASA Astrophysics Data System (ADS)

Nesbitt, S. W.; Salio, P. V.; Varble, A.; Trapp, R. J.; Roberts, R. R.; Dominguez, F.; Machado, L.; Saulo, C.

2017-12-01

Subtropical South America is host to many types of weather and climate hazards. The convective systems that initiate near and apart from the complex terrain of the Andes and Sierras de Córdoba are by many measures the most intense in the world, producing hazards such as damaging winds, hail, tornadoes, extreme and unusual lightning behavior, and flash and riverine flooding. These systems are modulated by interannual, intraseasonal, and synoptic drivers, however multi-scale models suffer from extreme biases in low level temperature and humidity due to their poor representation of organized convection and representation of convection near complex terrain, which hampers predictive skill of relevant processes across all timescales. To address these cross-cutting issues, we have proposed a large, multi-agency international field campaign called RELAMPAGO-CACTI, which will address key gaps in physical process understanding in the production of convective storms in this region. RELAMPAGO (Remote sensing of Electrification, Lightning, And Mesoscale/microscale Processes with Adaptive Ground Observations), funded by NSF/NOAA/NASA/MinCyT/FAPESP, will be a 24-month hydrological-meteorological field campaign, with an intensive observing period 1 Nov - 15 Dec 2018 in the near the Sierras de Córdoba (SDC), the Andes foothills near Mendoza, and the region near São Borja, Brazil. A complementary funded 7-month DOE field campaign called Clouds, Aerosols, and Complex Terrain Interactions (CACTI), which will focus on detailed observations of cloud and aerosol lifecycle near the SDC while an intensive observing period featuring aircraft observations will match RELAMPAGO's. While collecting the observations will enhance knowledge of the processes acting to modulate extremes in the region, a coordinated modeling effort will aim to evaluate coupled weather, climate, and hydrologic models using RELAMPAGO-CACTI observations. In addition, partnerships with the Servicio Meteorológico Nacional (SMN) of Argentina and Brazil's Centro de Previsão de Tempo e Estudos Climáticos (CPTEC), as well as related international and local societal impacts projects such as the World Meteorological Organization's High-Impact Weather project will enable improved end-to-end impacts predictions in this vulnerable region.

An integrated surface-geophysical investigation of the University of Connecticut landfill, Storrs, Connecticut, 2000

USGS Publications Warehouse

Johnson, Carole D.; Dawson, C.B.; Belaval, Marcel; Lane, John W.

2002-01-01

A surface-geophysical investigation to characterize the hydrogeology and contaminant distribution of the former landfill area at the University of Connecticut in Storrs, Connecticut, was conducted in 2000 to supplement the preliminary hydrogeologic assessment of the contamination of soil, surface water, and ground water at the site. A geophysical-toolbox approach was used to characterize the hydrogeology and contaminant distribution of the former landfill. Two-dimensional direct-current resistivity, inductive terrain-conductivity, and seismic-refraction surface-geophysical data were collected and interpreted in an iterative manner with exploratory drilling, borehole geophysics, and hydraulic testing. In this investigation, a geophysical-toolbox approach was used to 1) further define previously identified conductive anomalies and leachate plumes; 2) identify additional leachate plumes, possible fracture zones, and (or) conductive lithologic layers in the bedrock; and 3) delineate bedrock-surface topography in the drainage valleys north and south of the landfill. Resistivity and terrain-conductivity surveys were used to further delineate previously identified geophysical anomalies to the north and southwest of the landfill. A conductive anomaly identified in the terrain-conductivity survey to the north of the landfill in 2000 had a similar location and magnitude as an anomaly identified in terrain-conductivity surveys conducted in 1998 and 1999. Collectively, these surveys indicated that the magnitude of the conductive anomaly decreased with depth and with distance from the landfill. These anomalies indicated landfill leachate in the overburden and shallow bedrock. Results of previous surface-geophysical investigations southwest of the landfill indicated a shallow conductive anomaly in the overburden that extended into the fractured-bedrock aquifer. This conductive anomaly had a sheet-like geometry that had a north-south strike, dipped to the west, and terminated abruptly about 450 feet southwest of the landfill. The sheet-like conductive anomaly was interpreted as a fractured, conductive lithologic feature filled with conductive fluids. To further delineate this anomaly, two two-dimensional resistivity profiles were collected west of the sheet-like conductive anomaly to assess the possibility that the sheet-like conductive anomaly continued to the west in its down-dip direction. Each of the north-south oriented resistivity profiles showed bullet-shaped rather than linear-shaped anomalies, with a relatively smaller magnitude of conductivity than the sheet-like conductive anomaly to the east. If these bullet-like features are spatially connected, they may represent a linear, or pipe-like, conductive anomaly in the bedrock with a trend of N290?E and a plunge of 12?. Additional surveys were conducted to assess the apparent southern termination of the sheet-like conductive feature. Terrain-conductivity surveys indicated the sheet-like feature was not continuous to the south. A two-dimensional resistivity line and a coincident terrain-conductivity profile indicated the presence of a steep, eastward dipping, low magnitude, electrically conductive anomaly on the eastern end of the profile. Although the sheet-like conductive anomaly apparently did not continue to the south, the survey conducted in 2000 identified an isolated, weak conductive anomaly south of the previously identified anomaly. Inductive terrain-conductivity surveys performed north of the sheet-like conductive anomaly and west of the landfill indicated the anomaly did not extend to the north into the area of the former chemical-waste disposal pits. No conductive plumes or conductive features were observed in the subsurface bedrock west of the landfill. A conductive anomaly was identified in the southern section of the new terrain-conductivity grid. The magnitude and distribution of the apparent conductivity of this anomaly was identified as a nearly vertica

Multispectral Terrain Background Simulation Techniques For Use In Airborne Sensor Evaluation

NASA Astrophysics Data System (ADS)

Weinberg, Michael; Wohlers, Ronald; Conant, John; Powers, Edward

1988-08-01

A background simulation code developed at Aerodyne Research, Inc., called AERIE is designed to reflect the major sources of clutter that are of concern to staring and scanning sensors of the type being considered for various airborne threat warning (both aircraft and missiles) sensors. The code is a first principles model that could be used to produce a consistent image of the terrain for various spectral bands, i.e., provide the proper scene correlation both spectrally and spatially. The code utilizes both topographic and cultural features to model terrain, typically from DMA data, with a statistical overlay of the critical underlying surface properties (reflectance, emittance, and thermal factors) to simulate the resulting texture in the scene. Strong solar scattering from water surfaces is included with allowance for wind driven surface roughness. Clouds can be superimposed on the scene using physical cloud models and an analytical representation of the reflectivity obtained from scattering off spherical particles. The scene generator is augmented by collateral codes that allow for the generation of images at finer resolution. These codes provide interpolation of the basic DMA databases using fractal procedures that preserve the high frequency power spectral density behavior of the original scene. Scenes are presented illustrating variations in altitude, radiance, resolution, material, thermal factors, and emissivities. The basic models utilized for simulation of the various scene components and various "engineering level" approximations are incorporated to reduce the computational complexity of the simulation.

Examination of climatological wind patterns and simulated pollen dispersion in a complex island environment

NASA Astrophysics Data System (ADS)

Viner, Brian J.; Arritt, Raymond W.; Westgate, Mark E.

2017-08-01

Complex terrain creates small-scale circulations which affect pollen dispersion but may be missed by meteorological observing networks and coarse-grid meteorological models. On volcanic islands, these circulations result from differing rates of surface heating between land and sea as well as rugged terrain. We simulated the transport of bentgrass, ryegrass, and maize pollen from 30 sources within the agricultural regions of the Hawaiian island Kaua'i during climatological conditions spanning season conditions and the La Niña, El Niño, and neutral phases of the El Niño-Southern Oscillation. Both pollen size and source location had major effects on predicted dispersion over and near the island. Three patterns of pollen dispersion were identified in response to prevailing wind conditions: southwest winds transported pollen inland, funneling pollen grains through valleys; east winds transported pollen over the ocean, with dispersive tails for the smallest pollen grains following the mean wind and extending as far as the island of Ni'ihau 35 km away; and northeast winds moved pollen inland counter to the prevailing flow due to a sea breeze circulation that formed over the source region. These results are the first to predict the interactions between complex island terrain and local climatology on grass pollen dispersion. They demonstrate how numerical modeling can provide guidance for field trials by illustrating the common flow regimes present in complex terrain, allowing field trials to focus on areas where successful sampling is more likely to occur.

Comparison of MODIS and SWAT evapotranspiration over a complex terrain at different spatial scales

NASA Astrophysics Data System (ADS)

Abiodun, Olanrewaju O.; Guan, Huade; Post, Vincent E. A.; Batelaan, Okke

2018-05-01

In most hydrological systems, evapotranspiration (ET) and precipitation are the largest components of the water balance, which are difficult to estimate, particularly over complex terrain. In recent decades, the advent of remotely sensed data based ET algorithms and distributed hydrological models has provided improved spatially upscaled ET estimates. However, information on the performance of these methods at various spatial scales is limited. This study compares the ET from the MODIS remotely sensed ET dataset (MOD16) with the ET estimates from a SWAT hydrological model on graduated spatial scales for the complex terrain of the Sixth Creek Catchment of the Western Mount Lofty Ranges, South Australia. ET from both models was further compared with the coarser-resolution AWRA-L model at catchment scale. The SWAT model analyses are performed on daily timescales with a 6-year calibration period (2000-2005) and 7-year validation period (2007-2013). Differences in ET estimation between the SWAT and MOD16 methods of up to 31, 19, 15, 11 and 9 % were observed at respectively 1, 4, 9, 16 and 25 km2 spatial resolutions. Based on the results of the study, a spatial scale of confidence of 4 km2 for catchment-scale evapotranspiration is suggested in complex terrain. Land cover differences, HRU parameterisation in AWRA-L and catchment-scale averaging of input climate data in the SWAT semi-distributed model were identified as the principal sources of weaker correlations at higher spatial resolution.

Scientific rationale for selecting northwest Isidis Planitia (14 deg - 17 deg N latitude, 278 deg - 281 deg longitude) as a potential Mars Pathfinder landing site

NASA Technical Reports Server (NTRS)

Parker, Tim J.; Rice, Jim W.

1994-01-01

The northwest Isidis Basin offers a unique opportunity to land near a fretted terrain lowland/upland boundary that meets both the latitudinal and elevation requirements imposed on the spacecraft. The landing site lies east of erosional scarps and among remnant massif inselbergs of the Syrtis Major volcanic plains. The plains surface throughout Isidis exhibits abundant, low-relief mounds that are the local expression of the 'thumbprint terrain' that is common within a few hundred kilometers of the lowland/upland boundary. The massif inselbergs are not as numerous nor as massive as those fretted terrains to the northwest, so local slopes are not expected to be steep. Neither feature should pose a serious threat to the lander. Landing on or adjacent to one of these features would enhance the science return and would help to pinpoint the landing site in Viking and subsequent orbiter images by offering views of landmarks beyond the local horizon.

Ganymede - close up photos

NASA Technical Reports Server (NTRS)

1979-01-01

Two close-up photos of Ganymede, largest of Jupiter's 13 moons, were obtained on July 8 by Voyager 2 from 86,000 miles (top) and 192,000 miles. They show different views of the largest block of dark, heavily cratered terrain seen on the giant moon. The bottom image shows objects three to four miles across; has a resolution of about 1.5 miles. The light, linear stripes recurring across the dark region resemble the outer rings of the large ring structure on Callisto. If these features are in fact related to an ancient ring structure formed by a large impact, their small curvature suggests that the original structure was even larger than one seen on Callisto. There is no apparent trace now of the center of this suggested structure, which must have been destroyed by the resurfacing evident over most of Ganymede in the grooved terrain. Another interpretation is that these features are not impact-related rings but are internally produced fractures crossing the dark terrain, similar to the grooved bands.

Photographer : JPL Range : top- 86,000 miles bottom- 192,000 mi. These two close-ups of Ganymede,

NASA Technical Reports Server (NTRS)

1979-01-01

Photographer : JPL Range : top- 86,000 miles bottom- 192,000 mi. These two close-ups of Ganymede, the largest of Jupiter's 13 moons, show different views of the largest block of dark, heavily cratered terrain. The bottom image shows objects 3 or 4 miles across, with resolution of about 1.5 miles. The light, linear stripes recurring across the dark region resemble the outer rings of the large ring structure around Callisto. If these features are related to an ancient ring structure formed by a large impact, their small curvature suggests that the original structure was even larger than one seen on Callisto. There is no apparent trace now of the center of this suggested structure, which must have been destroyed by the resurfacing evident over most of Ganymede in the grooved terrain. Another interpretation is that these features are not impact-related rings, but rather internally produced fractures crossing the dark terrain, similiar to the grooved bands.

Photographer : JPL Range : 312, 000 kilometers (195,000 miles) This photo of Ganymede (Ice Giant)

NASA Technical Reports Server (NTRS)

1979-01-01

Photographer : JPL Range : 312, 000 kilometers (195,000 miles) This photo of Ganymede (Ice Giant) was taken from Voyager 2 and shows features down to about 5 to 6 kilometers across. Different types of terrain common on Ganymede's surface are visible. 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 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 flatteded by glacier-like flows.

Cerberus

NASA Technical Reports Server (NTRS)

2002-01-01

(Released 24 April 2002) The Science The Cerberus feature is a relatively dark region at the southeastern edge of the huge Elysium Mons volcanic complex. It was visible to early astronomers of Mars because it was a distinctive dark spot on a large bright region of the planet. Today we recognize that the Cerberus region encompasses a range of geologic terrains from relatively young and smooth lava flows to the very rugged, ancient eroded landscape seen in this THEMIS image. The Cerberus feature has also proven to be ephemeral. Compared to just 20 years ago when the Viking orbiter instruments viewed the planet, the Cerberus feature has shrunk down from its original length of roughly 1000 kilometers to just a few isolated dark splotches of just a few 100 kilometers. This is testament to the active eolian environment on Mars where global dust storms can lift and then later deposit significant amounts of dust, brightening formerly dark surfaces. The THEMIS image occurs in a portion of Cerberus that remains relatively dark and dust-free although in the bottommost portion of the image are faint, criss-crossing lines that likely are dust devil tracks. The abundant dune-like features covering many of the low, smooth surfaces are similar to those found in many places across the planet. They are evidence of the interaction of wind and movable particles at the surface but not necessarily in today's environment. In many other places on Mars they are clearly inactive; relicts of a different climate. The Story Hellhound of Greek mythology, Cerberus was the three-headed, dragon-tailed dog that stood guard at the opening to the underworld. This rough-and-tumble Mars terrain looks just as fierce and foreboding. At the edge of the huge Elysium Mons volcano complex, the Cerberus area appeared as a dark spot to early Mars astronomers in an otherwise bright region of the planet. If this dark area seems somewhat hellish to your imagination too, you'll be glad to know that the Martian wind has been brightening up the area. Just twenty years ago, the Viking orbiters reached Mars for the first long-term studies of Mars up close. The Cerberus feature was then almost 600 miles long, but has now been vanquished down to few small splotches about 60 miles long. Call that a triumph of lightness upon the surface, but don't think that the force bringing back the light is gentle and kind. The Martian wind can kick up a fierce global dust storm that lifts up the bright Martian dust into the air and then blankets the surface with the brighter material as it settles down again. The ancient, eroded terrain in this image is still rather dark and dust free, so you might say it's one area where a mythical Cerberus still guards its shrinking territory. The wind teases it, however, by kicking up small, whirling dust devils that leave long, dark, scratchy tracks upon the land. Fields of dunes wrinkle the surface in places as well, but they may be permanently cemented upon the surface now, no longer able to blow and drift as they did in their younger days.

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 the NWS forecast offices for issuance of flash flood warnings. This study will evaluate the performance of MPE and NMQ QPE products using independent gauges, object identification techniques for spatial verification and impact on surface runoff using a distributed hydrologic model. The effort will consist of baseline evaluations of these QPE systems to determine which combination of algorithm features is appropriate as well as investigate new methods for combining the gage and radar data. The Russian River Basin in California is used to demonstrate the comparison methodology with data collected from several rainfall events in March 2012.

First results in terrain mapping for a roving planetary explorer

NASA Technical Reports Server (NTRS)

Krotkov, E.; Caillas, C.; Hebert, M.; Kweon, I. S.; Kanade, Takeo

1989-01-01

To perform planetary exploration without human supervision, a complete autonomous rover must be able to model its environment while exploring its surroundings. Researchers present a new algorithm to construct a geometric terrain representation from a single range image. The form of the representation is an elevation map that includes uncertainty, unknown areas, and local features. By virtue of working in spherical-polar space, the algorithm is independent of the desired map resolution and the orientation of the sensor, unlike other algorithms that work in Cartesian space. They also describe new methods to evaluate regions of the constructed elevation maps to support legged locomotion over rough terrain.

Fretted Terrain Valleys

NASA Technical Reports Server (NTRS)

2004-01-01

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

An improved Ångström-type model for estimating solar radiation over the Tibetan Plateau

USDA-ARS?s Scientific Manuscript database

Sunshine- and temperature-based empirical models are widely used for solar radiation estimation over the world, but the coefficients of the models are mostly site-dependent. The coefficients are expected to vary more under complex terrain conditions than under flat terrains. To test this hypothesis,...

Bayes classification of interferometric TOPSAR data

NASA Technical Reports Server (NTRS)

Michel, T. R.; Rodriguez, E.; Houshmand, B.; Carande, R.

1995-01-01

We report the Bayes classification of terrain types at different sites using airborne interferometric synthetic aperture radar (INSAR) data. A Gaussian maximum likelihood classifier was applied on multidimensional observations derived from the SAR intensity, the terrain elevation model, and the magnitude of the interferometric correlation. Training sets for forested, urban, agricultural, or bare areas were obtained either by selecting samples with known ground truth, or by k-means clustering of random sets of samples uniformly distributed across all sites, and subsequent assignments of these clusters using ground truth. The accuracy of the classifier was used to optimize the discriminating efficiency of the set of features that was chosen. The most important features include the SAR intensity, a canopy penetration depth model, and the terrain slope. We demonstrate the classifier's performance across sites using a unique set of training classes for the four main terrain categories. The scenes examined include San Francisco (CA) (predominantly urban and water), Mount Adams (WA) (forested with clear cuts), Pasadena (CA) (urban with mountains), and Antioch Hills (CA) (water, swamps, fields). Issues related to the effects of image calibration and the robustness of the classification to calibration errors are explored. The relative performance of single polarization Interferometric data classification is contrasted against classification schemes based on polarimetric SAR data.

Surface compositional variation on the comet 67P/Churyumov-Gerasimenko by OSIRIS data

NASA Astrophysics Data System (ADS)

Barucci, M. A.; Fornasier, S.; Feller, C.; Perna, D.; Hasselmann, H.; Deshapriya, J. D. P.; Fulchignoni, M.; Besse, S.; Sierks, H.; Forgia, F.; Lazzarin, M.; Pommerol, A.; Oklay, N.; Lara, L.; Scholten, F.; Preusker, F.; Leyrat, C.; Pajola, M.; Osiris-Rosetta Team

2015-10-01

Since the Rosetta mission arrived at the comet 67P/Churyumov-Gerasimenko (67/P C-G) on July 2014, the comet nucleus has been mapped by both OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System, [1]) NAC (Narrow Angle Camera) and WAC (Wide Angle Camera) acquiring a huge quantity of surface's images at different wavelength bands, under variable illumination conditions and spatial resolution, and producing the most detailed maps at the highest spatial resolution of a comet nucleus surface.67/P C-G's nucleus shows an irregular bi-lobed shape of complex morphology with terrains showing intricate features [2, 3] and a heterogeneity surface at different scales.

Identifying new surface constituents of icy moons using mid-infrared spectroscopy

NASA Astrophysics Data System (ADS)

Young, Cindy L.; Wray, James J.; Hand, Kevin P.; Poston, Michael J.; Carlson, Robert W.; Clark, Roger N.; Spencer, John R.; Jennings, Donald E.

2015-11-01

Spectroscopic compositional studies of the icy satellites can help us to better understand the formation and evolution of material in the outer solar system. The spectral complexity of the Saturnian satellite system as seen in reflected visible light suggests additional complexity may be present at mid-infrared wavelengths from which unique compositional information can be gleaned [1]. In addition, the mid-infrared is the region of the stronger fundamental diagnostic vibrational modes of many compounds. However, Cassini Composite Infrared Spectrometer (CIRS) surface compositional studies have received little attention to date.We are exploring the suitability of mid-infrared spectroscopy for discovering non-H2O compounds on icy moon surfaces. On the dark terrain of Iapetus, we find an emissivity feature at ~855 cm-1 and a potential doublet at 660 and 690 cm-1 that do not correspond to any known instrument artifacts [2]. We attribute the 855 cm-1 feature to fine-grained silicates, similar to those found in dust on Mars and in meteorites, which are nearly featureless at shorter wavelengths [3]. Although silicates on the dark terrains of Saturn’s icy moons have been suspected for decades, there have been no definitive prior detections. Serpentines measured at ambient conditions have features near 855 cm-1 and 660 cm-1 [4]. However, peaks can shift depending on temperature, pressure, and grain size, so measurements at Iapetus-like conditions are necessary for more positive identifications [e.g., 5].We measured the vacuum, low temperature (125 K) spectra of various fine-grained powdered silicates. We find that some of these materials do have emissivity features near 855 cm-1 and match the doublet. Identifying a specific silicate would provide clues into the sources and sinks of the dark material in the Saturnian system. We report on our ongoing exploration of the CIRS icy moon dataset and plans for future measurements in JPL’s Icy Worlds Simulation Lab.[1] Flasar, F.M., et al. (2004), Space Sci Rev, 115, 169.[2] Young, C.L., et al. (in review), ApJ Lett.[3] Christensen, P.R., et al. (2004), Sci, 306, 1733.[4] Bishop, J.L., et al. (2008), Clay Minerals, 43, 35.[5] Wray, J.J., et al. (2014), DPS 46th Meeting, Vol. 46.

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

NASA Astrophysics Data System (ADS)

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

2015-12-01

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

Soil organic carbon dynamics as affected by topography in southern California hillslopes systems

NASA Astrophysics Data System (ADS)

Fissore, C.; Dalzell, B. J.; Berhe, A. A.; Evans, M.; Voegtle, M.; Wu, A. M.

2015-12-01

Active topography is a predominant feature of Southern California's landscapes where intense erosion and depositional processes can influence SOC translocation and accumulation and where changes in chemical, physical, and topographic conditions may affect long-term stability of SOC. Considering the large variability in SOC content across areas with active topography, it is necessary to develop landscape-scale stratifications of sampling that capture SOC variability due to erosion and deposition processes at different topographic locations. To achieve this goal, landscape SOC needs to be assessed based on more than just slope position by taking into account specific topographic indices, such as slope class, curvature, and catchment area. In this work, we used a series of analytical approaches, including total and water extractable C fractions, ultraviolet absorbance, infrared spectroscopy and a radio-isotope tracer (137Cs) in combination with GIS and digital terrain attributes analyses to investigate the quality and distribution of SOC along the sloping landscape of Puente Hills Preserve, in Whittier, CA. The complex interaction of terrain attributes on erosion and depositional processes was evident from 137Cs analysis, which allowed us to identify depositional and eroding areas. Our findings indicate that greater SOC accumulation is associated with concave profile and plane curvature, when combined with low slope class. Slope appears to be the terrain attribute that most affects SOC content and slope effects persist at depth. Ultraviolet absorbance of water extractable OC and infrared spectroscopy of SOC allowed the identification of different levels of aromaticity and distribution of SOC moieties that have been correlated to rates of mineralization. Southern California, like other Mediterranean regions around the world, is expected to experience increasingly severe droughts, more intense erosion and more frequent fire perturbation - which can exacerbate erosion - in the context of a changing climate. For these reasons, our findings are relevant to make better predictions on future SOC dynamics in areas with evolving and complex three-dimensional landscapes.

Evaluation of a CFD-based Wind Model Optimized for ABL Flows: Comparisons with Observations from a Tall Isolated Mountain

NASA Astrophysics Data System (ADS)

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

2015-12-01

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 disciplines. Unfortunately, near-surface winds in complex terrain are not handled well by traditional modeling approaches. 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 wind model, WindNinja, developed for wildfire applications in complex terrain. The new version offers two options for flow simulations: 1) the native, fast-running mass-consistent method available in previous versions and 2) a CFD approach based on the OpenFOAM toolbox and optimized for ABL flows. The model is described and evaluations of predictions with surface wind data collected from a recent field campaign at a tall isolated mountain are presented. CFD models have typically been evaluated with data collected from relatively simple terrain (e.g., low-elevation hills such as Askervein and Bolund) compared to the highly rugged terrain found in many regions, such as the western U.S. Here we provide one of the first evaluations of a CFD model over real terrain with ruggedness approaching that of landscapes characteristic of the western U.S. and other regions prone to wildfire. A comparison of predictions from the native mass-consistent method and the new CFD method is provided.

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stalker, James R.; Bossert, James E.

1997-12-31

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

The western Wabigoon Subprovince, Superior Province, Canada: Archean greenstone succession in rifted basement complex

NASA Technical Reports Server (NTRS)

Edwards, G. R.; Davis, D. W.

1986-01-01

The Wabigoon Subprovince, interposed between the predominantly metasedimentary-plutonic and gneissic English River and Quetico Subprovinces to the north and south respectively, exposed Archean greenstone and granitoid rocks for a strike length of greater than 700 km. Based on predominating rock types, the western part of the subprovince is divided into two terrains: the northern Wabigoon volcano-sedimentary and pluonic terrain (NWW) and the Wabigoon Diapiric Axis terrain (WDA). Both the NWW and WDA are described according to volcanic sequence, geological faults, chemical composition and evolutionary history.

ARC-1979-A79-7097

NASA Image and Video Library

1979-07-08

Range : 85,000 kilometers (53,000 miles) This photo of Jupiter's satellite Ganymede shows ancient cratered terrain. A variety of impact craters of different ages are shown. The brightest craters are the youngest. The ejecta blankets fade with age. The center shows a bright patch that represents the rebounding of the floor of the crater. The dirty ice has lost all topography except for faint circular patterns. Also shown are the 'Callisto type' curved troughs and ridges that mark an ancient enormous impact basin. The basin itself has been destroyed by later geologic processes. Only the ring features are preserved on the ancient surface. Near the bottom of the picture, these curved features are trumcated by the younger grooved terrain.

Geological mapping of lunar highland crater Lalande: Topographic configuration, morphology and cratering process

NASA Astrophysics Data System (ADS)

Li, Bo; Ling, Zongcheng; Zhang, Jiang; Chen, Jian; Liu, ChangQing; Bi, Xiangyu

2018-02-01

Highland crater Lalande (4.45°S, 8.63°W; D = 23.4 km) is located on the PKT area of the lunar near side, southeast of the Mare Insularum. It is a complex crater in Copernican era and has three distinguishing features: high silicic anomaly, the highest Th abundance and special landforms on its floor. There are some low-relief bulges on the left of Lalande's floor with regular circle or ellipse shapes. They are ∼250-680 m wide and ∼30-91 m high with maximum flank slopes >20°. There are two possible scenarios for the formation of these low-relief bulges which are impact melt products or young silicic volcanic eruptions. We estimated the absolute model ages of the ejecta deposits, several melt ponds and the hummocky floor and determined the ratio of diameter and depth of the crater Lalande. In addition, we found some similar bugle features within other Copernican-aged craters and there were no volcanic source vents on Lalande's floor. Thus, we hypothesized that these low-relief bulges were most consistent with an origin of impact melts during the crater formation instead of small and young volcanic activities occurring on the floor. Based on Kaguya Terrain Camera (TC) ortho-mosaic and Digital Terrain Model (DTM) data produced by TC imagery in stereo, geological units and some linear features on the floor and wall of Lalande have been mapped. Eight geological units are organized by crater floor units: hummocky floor, central peak and low-relief bulges; and crater wall units: terraced walls, channeled and veneered walls, interior walls, mass wasting areas, blocky areas, and melt ponds. These geological units and linear features provided us a chance to understand some details of the cratering process and elevation differences on the floor. We proposed that subsidence due to melt cooling, late-stage wall collapse and rocks uplifted from beneath the surface could be the possible causes of the observed elevation differences on Lalande's floor.

A large-eddy simulation based power estimation capability for wind farms over complex terrain

NASA Astrophysics Data System (ADS)

Senocak, I.; Sandusky, M.; Deleon, R.

2017-12-01

There has been an increasing interest in predicting wind fields over complex terrain at the micro-scale for resource assessment, turbine siting, and power forecasting. These capabilities are made possible by advancements in computational speed from a new generation of computing hardware, numerical methods and physics modelling. The micro-scale wind prediction model presented in this work is based on the large-eddy simulation paradigm with surface-stress parameterization. The complex terrain is represented using an immersed-boundary method that takes into account the parameterization of the surface stresses. Governing equations of incompressible fluid flow are solved using a projection method with second-order accurate schemes in space and time. We use actuator disk models with rotation to simulate the influence of turbines on the wind field. Data regarding power production from individual turbines are mostly restricted because of proprietary nature of the wind energy business. Most studies report percentage drop of power relative to power from the first row. There have been different approaches to predict power production. Some studies simply report available wind power in the upstream, some studies estimate power production using power curves available from turbine manufacturers, and some studies estimate power as torque multiplied by rotational speed. In the present work, we propose a black-box approach that considers a control volume around a turbine and estimate the power extracted from the turbine based on the conservation of energy principle. We applied our wind power prediction capability to wind farms over flat terrain such as the wind farm over Mower County, Minnesota and the Horns Rev offshore wind farm in Denmark. The results from these simulations are in good agreement with published data. We also estimate power production from a hypothetical wind farm in complex terrain region and identify potential zones suitable for wind power production.

Reference evapotranspiration from coarse-scale and dynamically downscaled data in complex terrain: Sensitivity to interpolation and resolution

NASA Astrophysics Data System (ADS)

Strong, Courtenay; Khatri, Krishna B.; Kochanski, Adam K.; Lewis, Clayton S.; Allen, L. Niel

2017-05-01

The main objective of this study was to investigate whether dynamically downscaled high resolution (4-km) climate data from the Weather Research and Forecasting (WRF) model provide physically meaningful additional information for reference evapotranspiration (E) calculation compared to the recently published GridET framework that uses interpolation from coarser-scale simulations run at 32-km resolution. The analysis focuses on complex terrain of Utah in the western United States for years 1985-2010, and comparisons were made statewide with supplemental analyses specifically for regions with irrigated agriculture. E was calculated using the standardized equation and procedures proposed by the American Society of Civil Engineers from hourly data, and climate inputs from WRF and GridET were debiased relative to the same set of observations. For annual mean values, E from WRF (EW) and E from GridET (EG) both agreed well with E derived from observations (r2 = 0.95, bias < 2 mm). Domain-wide, EW and EG were well correlated spatially (r2 = 0.89), however local differences ΔE =EW -EG were as large as +439 mm year-1 (+26%) in some locations, and ΔE averaged +36 mm year-1. After linearly removing the effects of contrasts in solar radiation and wind speed, which are characteristically less reliable under downscaling in complex terrain, approximately half the residual variance was accounted for by contrasts in temperature and humidity between GridET and WRF. These contrasts stemmed from GridET interpolating using an assumed lapse rate of Γ = 6.5 K km-1, whereas WRF produced a thermodynamically-driven lapse rate closer to 5 K km-1 as observed in mountainous terrain. The primary conclusions are that observed lapse rates in complex terrain differ markedly from the commonly assumed Γ = 6.5 K km-1, these lapse rates can be realistically resolved via dynamical downscaling, and use of constant Γ produces differences in E of order as large as 102 mm year-1.

3D Visualization for Phoenix Mars Lander Science Operations

NASA Technical Reports Server (NTRS)

Edwards, Laurence; Keely, Leslie; Lees, David; Stoker, Carol

2012-01-01

Planetary surface exploration missions present considerable operational challenges in the form of substantial communication delays, limited communication windows, and limited communication bandwidth. A 3D visualization software was developed and delivered to the 2008 Phoenix Mars Lander (PML) mission. The components of the system include an interactive 3D visualization environment called Mercator, terrain reconstruction software called the Ames Stereo Pipeline, and a server providing distributed access to terrain models. The software was successfully utilized during the mission for science analysis, site understanding, and science operations activity planning. A terrain server was implemented that provided distribution of terrain models from a central repository to clients running the Mercator software. The Ames Stereo Pipeline generates accurate, high-resolution, texture-mapped, 3D terrain models from stereo image pairs. These terrain models can then be visualized within the Mercator environment. The central cross-cutting goal for these tools is to provide an easy-to-use, high-quality, full-featured visualization environment that enhances the mission science team s ability to develop low-risk productive science activity plans. In addition, for the Mercator and Viz visualization environments, extensibility and adaptability to different missions and application areas are key design goals.

Empirical downscaling of daily minimum air temperature at very fine resolutions in complex terrain

Treesearch

Zachary A. Holden; John T. Abatzoglou; Charles H. Luce; L. Scott Baggett

2011-01-01

Available air temperature models do not adequately account for the influence of terrain on nocturnal air temperatures. An empirical model for night time air temperatures was developed using a network of one hundred and forty inexpensive temperature sensors deployed across the Bitterroot National Forest, Montana. A principle component analysis (PCA) on minimum...

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

ERIC Educational Resources Information Center

Syzdykova, Guldana D.; Kurmankozhaev, Azimhan K.

2016-01-01

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

Modeling smoke plume patterns in drainage flows

Treesearch

M.A. Fosberg

1985-01-01

A three-dimensional diagnostic wind model for use in complex terrain has been combined with a three-dimensional trajectory and puff air quality model. The wind model utilizes a terrain following coordinate system and conserves both mass and momentum. The wind model provides the winds required by the predictive trajectory and puff dispersion model. Both the wind model...

Measuring and modeling CO2 and H2O fluxes in complex terrain

Treesearch

Diego A. Riveros-Iregui; Brian L. McGlynn

2008-01-01

The feedbacks between the water and the carbon cycles are of critical importance to global carbon balances. Forests and forest soils in northern latitudes are important carbon pools because of their potential as sinks for atmospheric carbon. However there are significant unknowns related to the effects of hydrologic variability, mountainous terrain, and landscape...

Environmental impacts of forest road construction on mountainous terrain.

PubMed

Caliskan, Erhan

2013-03-15

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

Monitoring Citrus Soil Moisture and Nutrients Using an IoT Based System.

PubMed

Zhang, Xueyan; Zhang, Jianwu; Li, Lin; Zhang, Yuzhu; Yang, Guocai

2017-02-23

Chongqing mountain citrus orchard is one of the main origins of Chinese citrus. Its planting terrain is complex and soil parent material is diverse. Currently, the citrus fertilization, irrigation and other management processes still have great blindness. They usually use the same pattern and the same formula rather than considering the orchard terrain features, soil differences, species characteristics and the state of tree growth. With the help of the ZigBee technology, artificial intelligence and decision support technology, this paper has developed the research on the application technology of agricultural Internet of Things for real-time monitoring of citrus soil moisture and nutrients as well as the research on the integration of fertilization and irrigation decision support system. Some achievements were obtained including single-point multi-layer citrus soil temperature and humidity detection wireless sensor nodes and citrus precision fertilization and irrigation management decision support system. They were applied in citrus base in the Three Gorges Reservoir Area. The results showed that the system could help the grower to scientifically fertilize or irrigate, improve the precision operation level of citrus production, reduce the labor cost and reduce the pollution caused by chemical fertilizer.

Estimation of Snow Particle Model Suitable for a Complex and Forested Terrain: Lessons from SnowEx

NASA Astrophysics Data System (ADS)

Gatebe, C. K.; Li, W.; Stamnes, K. H.; Poudyal, R.; Fan, Y.; Chen, N.

2017-12-01

SnowEx 2017 obtained consistent and coordinated ground and airborne remote sensing measurements over Grand Mesa in Colorado, which feature sufficient forested stands to have a range of density and height (and other forest conditions); a range of snow depth/snow water equivalent (SWE) conditions; sufficiently flat snow-covered terrain of a size comparable to airborne instrument swath widths. The Cloud Absorption Radiometer (CAR) data from SnowEx are unique and can be used to assess the accuracy of Bidirectional Reflectance-Distribution Functions (BRDFs) calculated by different snow models. These measurements provide multiple angle and multiple wavelength data needed for accurate surface BRDF characterization. Such data cannot easily be obtained by current satellite remote sensors. Compared to ground-based snow field measurements, CAR measurements minimize the effect of self-shading, and are adaptable to a wide variety of field conditions. We plan to use the CAR measurements as the validation data source for our snow modeling effort. By comparing calculated BRDF results from different snow models to CAR measurements, we can determine which model best explains the snow BRDFs, and is therefore most suitable for application to satellite remote sensing of snow parameters and surface energy budget calculations.

Role of surface and subsurface lateral water flows on summer precipitation in a complex terrain region: A WRF-Hydro case-study for Southern Germany

NASA Astrophysics Data System (ADS)

Rummler, Thomas; Arnault, Joel; Gochis, David; Kunstmann, Harald

2017-04-01

Recent developments in hydrometeorological modeling aim towards more sophisticated treatment of terrestrial hydrologic processes. The standard version of the Weather Research and Forecasting (WRF) model describes terrestrial water transport as a purely vertical process. The hydrologically enhanced version of WRF, namely WRF-Hydro, does account for lateral terrestrial water flows, which allows for a more comprehensive process description of the interdependencies between water- and energy fluxes at the land-atmosphere interface. In this study, WRF and WRF-Hydro are applied to the Bavarian Alpine region in southern Germany, a complex terrain landscape in a relatively humid, mid-latitude climate. Simulation results are validated with gridded and station observation of precipitation, temperature and river discharge. Differences between WRF and WRF-Hydro results are investigated with a joint atmospheric-terrestrial water budget analysis. Changes in the partitioning in (near-) surface runoff and percolation are prominent. However, values for evapotranspiration ET feature only marginal variations, suggesting that soil moisture content is not a limiting factor of ET in this specific region. Simulated precipitation fields during isolated summertime events still show appreciable differences, while differences in large-scale, multi-day rainy periods are less substantial. These differences are mainly related to differences in the moisture in- and outflow terms of the atmospheric water budget induced by the surface and sub-surface lateral redistribution of soil moisture in WRF-Hydro.

Remote sensing evidence of lava-ground ice interactions associated with the Lost Jim Lava Flow, Seward Peninsula, Alaska

NASA Astrophysics Data System (ADS)

Marcucci, Emma C.; Hamilton, Christopher W.; Herrick, Robert R.

2017-12-01

Thermokarst terrains develop when ice-bearing permafrost melts and causes the overlying surface to subside or collapse. This process occurs widely throughout Arctic regions due to environmental and climatological factors, but can also be induced by localized melting of ground ice by active lava flows. The Lost Jim Lava Flow (LJLF) on the Seward Peninsula of Alaska provides evidence of former lava-ground ice interactions. Associated geomorphic features, on the scale of meters to tens of meters, were identified using satellite orthoimages and stereo-derived digital terrain models. The flow exhibits positive- and mixed-relief features, including tumuli ( N = 26) and shatter rings ( N = 4), as well as negative-relief features, such as lava tube skylights ( N = 100) and irregularly shaped topographic depressions ( N = 1188) that are interpreted to include lava-rise pits and lava-induced thermokarst terrain. Along the margins of the flow, there are also clusters of small peripheral pits that may be the products of meltwater or steam escape. On Mars, we observed morphologically similar pits near lava flow margins in northeastern Elysium Planitia, which suggests a common formation mechanism. Investigating the LJLF may therefore help to elucidate processes of lava-ground ice interaction on both Earth and Mars.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Newsom, Rob K.; Berg, Larry K.; Pekour, Mikhail S.

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 2DVarmore » 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.« less

Examination of climatological wind patterns and simulated pollen dispersion in a complex island environment

DOE PAGES

Viner, Brian J.; Arritt, Raymond W.; Westgate, Mark E.

2017-03-29

Complex terrain creates small-scale circulations which affect pollen dispersion but may be missed by meteorological observing networks and coarse-grid meteorological models. On volcanic islands, these circulations result from differing rates of surface heating between land and sea as well as rugged terrain. We simulated the transport of bentgrass, ryegrass, and maize pollen from 30 sources within the agricultural regions of the Hawaiian island Kaua’i during climatological conditions spanning season conditions and the La Niña, El Niño, and neutral phases of the El Niño-Southern Oscillation. Both pollen size and source location had major effects on predicted dispersion over and near themore » island. Three patterns of pollen dispersion were identified in response to prevailing wind conditions: southwest winds transported pollen inland, funneling pollen grains through valleys; east winds transported pollen over the ocean, with dispersive tails for the smallest pollen grains following the mean wind and extending as far as the island of Ni’ihau 35 km away; and northeast winds moved pollen inland counter to the prevailing flow due to a sea breeze circulation that formed over the source region. These results are the first to predict the interactions between complex island terrain and local climatology on grass pollen dispersion. As a result, they demonstrate how numerical modeling can provide guidance for field trials by illustrating the common flow regimes present in complex terrain, allowing field trials to focus on areas where successful sampling is more likely to occur.« less

Examination of climatological wind patterns and simulated pollen dispersion in a complex island environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Viner, Brian J.; Arritt, Raymond W.; Westgate, Mark E.

Complex terrain creates small-scale circulations which affect pollen dispersion but may be missed by meteorological observing networks and coarse-grid meteorological models. On volcanic islands, these circulations result from differing rates of surface heating between land and sea as well as rugged terrain. We simulated the transport of bentgrass, ryegrass, and maize pollen from 30 sources within the agricultural regions of the Hawaiian island Kaua’i during climatological conditions spanning season conditions and the La Niña, El Niño, and neutral phases of the El Niño-Southern Oscillation. Both pollen size and source location had major effects on predicted dispersion over and near themore » island. Three patterns of pollen dispersion were identified in response to prevailing wind conditions: southwest winds transported pollen inland, funneling pollen grains through valleys; east winds transported pollen over the ocean, with dispersive tails for the smallest pollen grains following the mean wind and extending as far as the island of Ni’ihau 35 km away; and northeast winds moved pollen inland counter to the prevailing flow due to a sea breeze circulation that formed over the source region. These results are the first to predict the interactions between complex island terrain and local climatology on grass pollen dispersion. As a result, they demonstrate how numerical modeling can provide guidance for field trials by illustrating the common flow regimes present in complex terrain, allowing field trials to focus on areas where successful sampling is more likely to occur.« less

Pitted terrains on (1) Ceres and implications for shallow subsurface volatile distribution

PubMed Central

Platz, T.; Schorghofer, N.; Prettyman, T. H.; De Sanctis, M. C.; Crown, D. A.; Schmedemann, N.; Neesemann, A.; Kneissl, T.; Marchi, S.; Schenk, P. M.; Bland, M. T.; Schmidt, B. E.; Hughson, K. H. G.; Tosi, F.; Zambon, F.; Mest, S. C.; Yingst, R. A.; Williams, D. A.; Russell, C. T.; Raymond, C. A.

2017-01-01

Abstract Prior to the arrival of the Dawn spacecraft at Ceres, the dwarf planet was anticipated to be ice‐rich. Searches for morphological features related to ice have been ongoing during Dawn's mission at Ceres. Here we report the identification of pitted terrains associated with fresh Cerean impact craters. The Cerean pitted terrains exhibit strong morphological similarities to pitted materials previously identified on Mars (where ice is implicated in pit development) and Vesta (where the presence of ice is debated). We employ numerical models to investigate the formation of pitted materials on Ceres and discuss the relative importance of water ice and other volatiles in pit development there. We conclude that water ice likely plays an important role in pit development on Ceres. Similar pitted terrains may be common in the asteroid belt and may be of interest to future missions motivated by both astrobiology and in situ resource utilization. PMID:28989206

Pitted terrains on (1) Ceres and implications for shallow subsurface volatile distribution.

PubMed

Sizemore, H G; Platz, T; Schorghofer, N; Prettyman, T H; De Sanctis, M C; Crown, D A; Schmedemann, N; Neesemann, A; Kneissl, T; Marchi, S; Schenk, P M; Bland, M T; Schmidt, B E; Hughson, K H G; Tosi, F; Zambon, F; Mest, S C; Yingst, R A; Williams, D A; Russell, C T; Raymond, C A

2017-07-16

Prior to the arrival of the Dawn spacecraft at Ceres, the dwarf planet was anticipated to be ice-rich. Searches for morphological features related to ice have been ongoing during Dawn's mission at Ceres. Here we report the identification of pitted terrains associated with fresh Cerean impact craters. The Cerean pitted terrains exhibit strong morphological similarities to pitted materials previously identified on Mars (where ice is implicated in pit development) and Vesta (where the presence of ice is debated). We employ numerical models to investigate the formation of pitted materials on Ceres and discuss the relative importance of water ice and other volatiles in pit development there. We conclude that water ice likely plays an important role in pit development on Ceres. Similar pitted terrains may be common in the asteroid belt and may be of interest to future missions motivated by both astrobiology and in situ resource utilization.

Mass data graphics requirements for symbol generators: example 2D airport navagation and 3D terrain function

NASA Astrophysics Data System (ADS)

Schiefele, Jens; Bader, Joachim; Kastner, S.; Wiesemann, Thorsten; von Viebahn, Harro

2002-07-01

Next generation of cockpit display systems will display mass data. Mass data includes terrain, obstacle, and airport databases. Display formats will be two and eventually 3D. A prerequisite for the introduction of these new functions is the availability of certified graphics hardware. The paper describes functionality and required features of an aviation certified 2D/3D graphics board. This graphics board should be based on low-level and hi-level API calls. These graphic calls should be very similar to OpenGL. All software and the API must be aviation certified. As an example application, a 2D airport navigation function and a 3D terrain visualization is presented. The airport navigation format is based on highly precise airport database following EUROCAE ED-99/RTCA DO-272 specifications. Terrain resolution is based on EUROCAE ED-98/RTCA DO-276 requirements.

Pitted terrains on (1) Ceres and implications for shallow subsurface volatile distribution

USGS Publications Warehouse

Sizemore, H.G.; Platz, Thomas; Schorghofer, Norbert; Prettyman, Thomas; De Sanctis, Maria Christina; Crown, David A.; Schmedemann, Nico; Nessemann, Andeas; Kneissl, Thomas; Simone Marchi,; Schenk, Paul M.; Bland, Michael T.; Schmidt, B.E.; Hughson, Kynan H.G.; Tosi, F.; Zambon, F; Mest, S.C.; Yingst, R.A.; Williams, D.A.; Russell, C.T.; Raymond, C.A.

2017-01-01

Prior to the arrival of the Dawn spacecraft at Ceres, the dwarf planet was anticipated to be ice-rich. Searches for morphological features related to ice have been ongoing during Dawn's mission at Ceres. Here we report the identification of pitted terrains associated with fresh Cerean impact craters. The Cerean pitted terrains exhibit strong morphological similarities to pitted materials previously identified on Mars (where ice is implicated in pit development) and Vesta (where the presence of ice is debated). We employ numerical models to investigate the formation of pitted materials on Ceres and discuss the relative importance of water ice and other volatiles in pit development there. We conclude that water ice likely plays an important role in pit development on Ceres. Similar pitted terrains may be common in the asteroid belt and may be of interest to future missions motivated by both astrobiology and in situ resource utilization.

ARC-1986-A86-7031

NASA Image and Video Library

1986-01-26

P-29515 BW Range: 42,000 kilometers (26,000 miles) This image of Miranda, obtained by Voyager 2 on approach, shows an unusual 'chevron' figure and regions of distinctly differing terrain on the Uranian moon. Grooved areas baring light and dark bands, distinct from other areas of mottled terrain, are visible at this resolution of about 600 meters (2,000 feet). The bright V-shaped feature in the grooved areas is the 'cheron' observed in earlier, lower-resolution images. Cutting across the bands are sinuous scarps, probably faults. Superimposed on both types of terrain are many bowl-shaped impact craters less than 5 km (3 mi) wide. The entire picture spans an area about 220 km (140 mi) across.

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.

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.

Geologic Mapping of Vesta

NASA Technical Reports Server (NTRS)

Yingst, R. A.; Mest, S. C.; Berman, D. C.; Garry, W. B.; Williams, D. A.; Buczkowski, D.; Jaumann, R.; Pieters, C. M.; De Sanctis, M. C.; Frigeri, A.;

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...

Extenstional terrain formation in icy satellites: Implications for ocean-surface interaction

NASA Astrophysics Data System (ADS)

Howell, Samuel M.; Pappalardo, Robert T.

2017-10-01

Europa and Ganymede, Galilean satellites of Jupiter, exhibit geologic activity in their outer H2O ice shells that might convey material from water oceans within the satellites to their surfaces. Imagery from the Voyager and Galileo spacecraft reveal surfaces rich with tectonic deformation, including dilational bands on Europa and groove lanes on Ganymede. These features are generally attributed to the extension of a brittle ice lithosphere overlaying a possibly convecting ice asthenosphere. To explore band formation and interaction with interior oceans, we employ fully visco-elasto-plastic 2-D models of faulting and convection with complex, realistic pure ice rheologies. In these models, material entering from below is tracked and considered to be “fossilized ocean,” ocean material that has frozen into the ice shell and evolves through geologic time. We track the volume fraction of fossil ocean material in the ice shell as a function of depth, and the exposure of both fresh ice and fossil ocean material at the ice shell surface. To explore the range in extensional terrains, we vary ice shell thickness, fault localization, melting-temperature ice viscosity, and the presence of pre-existing weaknesses. Mechanisms which act to weaken the ice shell and thin the lithosphere (e.g. vigorous convection, thinner shells, pre-existing weaknesses) tend to plastically yield to form smooth bands at high strains, and are more likely to incorporate fossil ocean material in the ice shell and expose it at the surface. In contrast, lithosphere strengthened by rapid fault annealing or increased viscosity, for example, exhibits large-scale tectonic rifting at low strains superimposed over pre-existing terrains, and inhibits the incorporation and delivery of fossil ocean material to the surface. Thus, our results identify a spectrum of extensional terrain formation mechanisms as linked to lithospheric strength, rather than specific mechanisms that are unique to each type of band, and discuss where in this spectrum ocean material incorporated at the bottom of the ice shell may be exposed on the satellite surface.

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

Treesearch

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

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...

For wind turbines in complex terrain, the devil is in the detail

NASA Astrophysics Data System (ADS)

Lange, Julia; Mann, Jakob; Berg, Jacob; Parvu, Dan; Kilpatrick, Ryan; Costache, Adrian; Chowdhury, Jubayer; Siddiqui, Kamran; Hangan, Horia

2017-09-01

The cost of energy produced by onshore wind turbines is among the lowest available; however, onshore wind turbines are often positioned in a complex terrain, where the wind resources and wind conditions are quite uncertain due to the surrounding topography and/or vegetation. In this study, we use a scale model in a three-dimensional wind-testing chamber to show how minor changes in the terrain can result in significant differences in the flow at turbine height. These differences affect not only the power performance but also the life-time and maintenance costs of wind turbines, and hence, the economy and feasibility of wind turbine projects. We find that the mean wind, wind shear and turbulence level are extremely sensitive to the exact details of the terrain: a small modification of the edge of our scale model, results in a reduction of the estimated annual energy production by at least 50% and an increase in the turbulence level by a factor of five in the worst-case scenario with the most unfavorable wind direction. Wind farm developers should be aware that near escarpments destructive flows can occur and their extent is uncertain thus warranting on-site field measurements.

Curvilinear ridges and related features in southwest Cydonia Mensae, Mars

NASA Technical Reports Server (NTRS)

Parker, Timothy J.; Schneeberger, Dale M.; Pieri, David C.; Saunders, R. Stephen

1987-01-01

Examined is a region on Mars in southwest Cydonia Mensae (32 deg lat., 17 deg long.) just northwest of the lowland/upland boundary escarpment. The dominant morphological features in this region are the clusters of large massifs and plateau outliers (PI), knobby material (K), and smooth lowland plains (Ps). Surrounding the clusters and linking many isolated knobs is a system of curvilinear ridges and arcuate terrain boundaries which tend to separate the massifs and knobs from the smooth plains. Curvilinear ridges are arcuate to nearly linear and smoother in plan than wrinkle ridges and show no apparent correlation with regional structural grain. They are typically 5 to 10 km long but can range from as little as 2 or 3 km to greater than 50 km long. The widths vary from about 100 m to as much as 2 km. Curvilinear ridges are most numerous within 100 km of the lowland/upland boundary escarpment and are associated with massifs and knobby terrain. Arcuate terrain boundaries appear between units of different apparent albedo or arcuate breaks in slope.

Venus: Preliminary geologic mapping of northern Atla Regio

NASA Technical Reports Server (NTRS)

Nikishin, A. M.; Burba, G. A.

1992-01-01

A preliminary geologic map of C1 sheet 15N197 was compiled according to Magellan data. Northern Atla Regio is dominantly a volcanic plain with numerous volcanic features: radar-bright and -dark flows and spots, shield volcanos, volcanic domes and hills with varied morphology, and coronalike constructions. Tesserae are the oldest terrains semiflooded by plain materials. There are many lineated terrains on this territory. They are interpreted as old, partly buried ridge belts. Lineated terrains have intermediate age between young plains and old tesserae. Ozza Mons and Sapas Mons are the high shield volcanos. The prominent structure of northern Atla Regio is Ganis Chasma rift. The rift dissected the volcanic plain and evolved nearly contemporaneously with Ozza Mons shield volcano. Ganis Chasma rift valley is highly fractured and bounded by fault scarps. There are a few relatively young volcanic features in the rift valley. The rift originated due to 5-10 percent crustal extension and crustal subsidence according to analysis of fracturing and rift valley geometry. Ganis Chasma is characterized by rift shoulder uplifts. Geological structures of Alta Regio and Beta Regio are very similar as assumed earlier.

Planet Four: Terrains - Discovery of araneiforms outside of the South Polar layered deposits

NASA Astrophysics Data System (ADS)

Schwamb, Megan E.; Aye, Klaus-Michael; Portyankina, Ganna; Hansen, Candice J.; Allen, Campbell; Allen, Sarah; Calef, Fred J.; Duca, Simone; McMaster, Adam; Miller, Grant R. M.

2018-07-01

We present the results of a systematic mapping of seasonally sculpted terrains on the South Polar region of Mars with the Planet Four: Terrains (P4T) online citizen science project. P4T enlists members of the general public to visually identify features in the publicly released Mars Reconnaissance Orbiter Context Camera (CTX) images. In particular, P4T volunteers are asked to identify: (1) araneiforms (including features with a central pit and radiating channels known as 'spiders'); (2) erosional depressions, troughs, mesas, ridges, and quasi-circular pits characteristic of the South Polar Residual Cap (SPRC) which we collectively refer to as 'Swiss cheese terrain', and (3) craters. In this work we present the distributions of our high confidence classic spider araneiforms and Swiss cheese terrain identifications in 90 CTX images covering 11% of the South polar regions at latitudes ≤ -75° N. We find no locations within our high confidence spider sample that also have confident Swiss cheese terrain identifications. Previously spiders were reported as being confined to the South Polar Layered Deposits (SPLD). Our work has provided the first identification of spiders at locations outside of the SPLD, confirmed with high resolution HiRISE (High Resolution Imaging Science Experiment) imaging. We find araneiforms on the Amazonian and Hesperian polar units and the Early Noachian highland units, with 75% of the identified araneiform locations in our high confidence sample residing on the SPLD. With our current coverage, we cannot confirm whether these are the only geologic units conducive to araneiform formation on the Martian South Polar region. Our results are consistent with the current CO2 jet formation scenario with the process exploiting weaknesses in the surface below the seasonal CO2 ice sheet to carve araneiform channels into the regolith over many seasons. These new regions serve as additional probes of the conditions required for channel creation in the CO2 jet process.

Evaluating terrain based criteria for snow avalanche exposure ratings using GIS

NASA Astrophysics Data System (ADS)

Delparte, Donna; Jamieson, Bruce; Waters, Nigel

2010-05-01

Snow avalanche terrain in backcountry regions of Canada is increasingly being assessed based upon the Avalanche Terrain Exposure Scale (ATES). ATES is a terrain based classification introduced in 2004 by Parks Canada to identify "simple", "challenging" and "complex" backcountry areas. The ATES rating system has been applied to well over 200 backcountry routes, has been used in guidebooks, trailhead signs and maps and is part of the trip planning component of the AVALUATOR™, a simple decision-support tool for backcountry users. Geographic Information Systems (GIS) offers a means to model and visualize terrain based criteria through the use of digital elevation model (DEM) and land cover data. Primary topographic variables such as slope, aspect and curvature are easily derived from a DEM and are compatible with the equivalent evaluation criteria in ATES. Other components of the ATES classification are difficult to extract from a DEM as they are not strictly terrain based. An overview is provided of the terrain variables that can be generated from DEM and land cover data; criteria from ATES which are not clearly terrain based are identified for further study or revision. The second component of this investigation was the development of an algorithm for inputting suitable ATES criteria into a GIS, thereby mimicking the process avalanche experts use when applying the ATES classification to snow avalanche terrain. GIS based classifications were compared to existing expert assessments for validity. The advantage of automating the ATES classification process through GIS is to assist avalanche experts with categorizing and mapping remote backcountry terrain.

Satellite remote sensing of landscape freeze/thaw state dynamics for complex Topography and Fire Disturbance Areas Using multi-sensor radar and SRTM digital elevation models

NASA Technical Reports Server (NTRS)

Podest, Erika; McDonald, Kyle; Kimball, John; Randerson, James

2003-01-01

We characterize differences in radar-derived freeze/thaw state, examining transitions over complex terrain and landscape disturbance regimes. In areas of complex terrain, we explore freezekhaw dynamics related to elevation, slope aspect and varying landcover. In the burned regions, we explore the timing of seasonal freeze/thaw transition as related to the recovering landscape, relative to that of a nearby control site. We apply in situ biophysical measurements, including flux tower measurements to validate and interpret the remotely sensed parameters. A multi-scale analysis is performed relating high-resolution SAR backscatter and moderate resolution scatterometer measurements to assess trade-offs in spatial and temporal resolution in the remotely sensed fields.

The Importance of Lake Overflow Floods for Early Martian Landscape Evolution: Insights From Licus Vallis

NASA Technical Reports Server (NTRS)

Goudge, T. A.; Fassett, C. I.

2017-01-01

Open-basin lake outlet valleys are incised when water breaches the basin-confining topography and overflows. Outlet valleys record this flooding event and provide insight into how the lake and surrounding terrain evolved over time. Here we present a study of the paleolake outlet Licus Vallis, a >350 km long, >2 km wide, >100 m deep valley that heads at the outlet breach of an approx.30 km diameter impact crater. Multiple geomorphic features of this valley system suggest it records a more complex evolution than formation from a single lake overflow flood. This provides unique insight into the paleohydrology of lakes on early Mars, as we can make inferences beyond the most recent phase of activity..

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

Structure of the nocturnal boundary layer over a complex terrain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parker, M.J.; Raman, S.

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 instrumentationmore » 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.« less

Structure of the nocturnal boundary layer over a complex terrain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parker, M.J.; Raman, S.

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 instrumentationmore » 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.« less

Structure of the nocturnal boundary layer over a complex terrain

NASA Astrophysics Data System (ADS)

Parker, M. J.; Raman, S.

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 sq km, 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.

Assessment of antipodal-impact terrains on Mars

NASA Astrophysics Data System (ADS)

Williams, David A.; Greeley, Ronald

1994-08-01

The regions anitpodal to Mars' three largest impact basins, Hellas, Isidis, and Argyre, were assessed for evidence of impact-induced disrupted terrains. Photogeology and computer modeling using the Simplified Arbitrary Lagrangian Eulerian (SALE) finite element code suggest that such terrains could have been found by the Hellas impact. Maximum antipodal pressures are 1100 MPa for Hellas, 520 MPa for Isidis, and 150 MPa for Argyre. The results suggest that if antipodal fracturing were associated with later volcanism, then Alba Patera may be related to the Hellas event, as proposed by Peterson (1978). Alba Patera is a unique volcano in the solar system, being a shield volcano which emitted large volume lava flows. This volcanism could be the result of the focusing of seismic energy which created a fractured region that served as a volcanic conduit for the future release of large volumes of magma. No disrupted terrain features are observed antipodal to the Isidis or Argyre basins, although some of the old fractures in Noctis Labyrinthus could have originated in response to the Isidis impact, and later have been reactivated by the Tharsis tectonics assumed to have produced Noctis. If the lower calculated antipodal pressures for Argyre were capable of producing disrupted terrains, then the terrains have been covered subsequently by volcanic or aeolian material, or modified beyond recognition.

Assessment of antipodal-impact terrains on Mars

NASA Technical Reports Server (NTRS)

Williams, David A.; Greeley, Ronald

1994-01-01

The regions anitpodal to Mars' three largest impact basins, Hellas, Isidis, and Argyre, were assessed for evidence of impact-induced disrupted terrains. Photogeology and computer modeling using the Simplified Arbitrary Lagrangian Eulerian (SALE) finite element code suggest that such terrains could have been found by the Hellas impact. Maximum antipodal pressures are 1100 MPa for Hellas, 520 MPa for Isidis, and 150 MPa for Argyre. The results suggest that if antipodal fracturing were associated with later volcanism, then Alba Patera may be related to the Hellas event, as proposed by Peterson (1978). Alba Patera is a unique volcano in the solar system, being a shield volcano which emitted large volume lava flows. This volcanism could be the result of the focusing of seismic energy which created a fractured region that served as a volcanic conduit for the future release of large volumes of magma. No disrupted terrain features are observed antipodal to the Isidis or Argyre basins, although some of the old fractures in Noctis Labyrinthus could have originated in response to the Isidis impact, and later have been reactivated by the Tharsis tectonics assumed to have produced Noctis. If the lower calculated antipodal pressures for Argyre were capable of producing disrupted terrains, then the terrains have been covered subsequently by volcanic or aeolian material, or modified beyond recognition.

Received signal strength and local terrain profile data for radio network planning and optimization at GSM frequency bands.

PubMed

Popoola, Segun I; Atayero, Aderemi A; Faruk, Nasir

2018-02-01

The behaviour of radio wave signals in a wireless channel depends on the local terrain profile of the propagation environments. In view of this, Received Signal Strength (RSS) of transmitted signals are measured at different points in space for radio network planning and optimization. However, these important data are often not publicly available for wireless channel characterization and propagation model development. In this data article, RSS data of a commercial base station operating at 900 and 1800 MHz were measured along three different routes of Lagos-Badagry Highway, Nigeria. In addition, local terrain profile data of the study area (terrain elevation, clutter height, altitude, and the distance of the mobile station from the base station) are extracted from Digital Terrain Map (DTM) to account for the unique environmental features. Statistical analyses and probability distributions of the RSS data are presented in tables and graphs. Furthermore, the degree of correlations (and the corresponding significance) between the RSS and the local terrain parameters were computed and analyzed for proper interpretations. The data provided in this article will help radio network engineers to: predict signal path loss; estimate radio coverage; efficiently reuse limited frequencies; avoid interferences; optimize handover; and adjust transmitted power level.

Vertical structure and microphysical characteristics of precipitation on the high terrain and lee side of the Olympic Mountains

NASA Astrophysics Data System (ADS)

Zagrodnik, J. P.; McMurdie, L. A.; Houze, R.

2017-12-01

As mid-latitude cyclones pass over coastal mountain ranges, the processes producing their clouds and precipitation are modified when they encounter complex terrain, leading to a maximum in precipitation fallout on the windward slopes and a minimum on the lee side. The precipitation that does reach the high terrain and lee side of a mountain range can be theoretically determined by a complex interaction between the dynamics of air lifting over the terrain, the thermodynamics of moist air, and the microphysical time required to grow particles large enough to fall out. To date, there have been few observational studies that have focused on the nonlinear microphysical processes contributing to the variability of precipitation that is received on the lee side slopes of a mountain range such as the Olympic Mountains. The 2015-16 Olympic Mountains Experiment (OLYMPEX) collected unprecedented observations on the high terrain and lee side of the Olympic Mountains including frequent soundings on Vancouver Island, dual-polarization Doppler radar, multi-frequency airborne radar, and ground-based particle size and crystal habit observations at the higher elevation Hurricane Ridge site. We utilize these observations to examine the evolution of the vertical structure and microphysical precipitation characteristics over the high terrain and leeside within the context of large-scale dynamic and thermodynamic conditions that evolve during the passage of cold season mid-latitude cyclones. The primary goal is to determine the degree to which the observed variability in lee side precipitation amount and microphysical properties are controlled by variations in temperature, flow speed and direction, shear, and stability associated with characteristic synoptic storm sectors and frontal passages.

Derivation of surface properties from Magellan altimetry data

NASA Astrophysics Data System (ADS)

Lovell, Amy J.; Schloerb, F. Peter; McGill, George E.

1992-12-01

The fit of the Hagfors model to the Magellan altimetry data provides a means to characterize the surface properties of Venus. However, the derived surface properties are only meaningful if the model provides a good representation of the data. The Hagfors model provides a good representation of the data. The Hagfors model is generally a realistic fit to surface scattering properties of a nadir-directed antenna such as the Magellan altimeter; however, some regions of the surface of Venus are poorly described by the existing model, according to the goodness of fit parameter provided on the ARCDR CD-ROMs. Poorly characterized regions need to be identified and fit to new models in order to derive more accurate surface properties for use in inferring the geological processes that affect the surface in those regions. We have compared the goodness of fit of the Hagfors model to the distribution of features across the planet, and preliminary results show a correlation between steep topographic slopes and poor fits to the standard model, as has been noticed by others. In this paper, we investigate possible relations between many classes of features and the ability of the Hagfors model to fit the observed echo profiles. In the regions that are not well characterized by existing models, we calculate new models that compensate for topographic relief in order to derive improved estimates of surface properties. Areas investigated to date span from longitude 315 through 45, at all latitudes covered by Magellan. A survey of those areas yields preliminary results that suggest that topographically high regions are well suited to the current implementation of the Hagfors model. Striking examples of such large-scale good fits are Alpha Regio, the northern edges of Lada Terra, and the southern edge of Ishtar Terra. Other features that are typically well fit are the rims of coronae such as Heng-O and the peaks of volcanos such as Gula Mons. Surprisingly, topographically low regions, such as the ubiquitous plains areas, are modeled poorly in comparison. However, this generalization has has exceptions: Lakshmi Planum is an elevated region that is not well fit compared to the rest of neighboring Ishtar, while the southern parts of topographically low Guinevere Planitia are characterized quite well by the Hagfors model. Features that are candidates for improved models are impact craters, coronae, ridges of significant scale, complex ridged terrains, moderate-sized mountains, and sharp terrain boundaries. These features are chosen because the goodness of fit is likely to be most affected either by departures from normal incidence angles or by sharp changes in terrain type within a single footprint. Most large features that are elevated with respect to their surroundings will suffer from steep slope effects, and smaller coronae and impact craters will probably suffer due to rapid changes in their appearance within a single footprint (10-20 km).

Derivation of surface properties from Magellan altimetry data

NASA Technical Reports Server (NTRS)

Lovell, Amy J.; Schloerb, F. Peter; Mcgill, George E.

1992-01-01

The fit of the Hagfors model to the Magellan altimetry data provides a means to characterize the surface properties of Venus. However, the derived surface properties are only meaningful if the model provides a good representation of the data. The Hagfors model provides a good representation of the data. The Hagfors model is generally a realistic fit to surface scattering properties of a nadir-directed antenna such as the Magellan altimeter; however, some regions of the surface of Venus are poorly described by the existing model, according to the goodness of fit parameter provided on the ARCDR CD-ROMs. Poorly characterized regions need to be identified and fit to new models in order to derive more accurate surface properties for use in inferring the geological processes that affect the surface in those regions. We have compared the goodness of fit of the Hagfors model to the distribution of features across the planet, and preliminary results show a correlation between steep topographic slopes and poor fits to the standard model, as has been noticed by others. In this paper, we investigate possible relations between many classes of features and the ability of the Hagfors model to fit the observed echo profiles. In the regions that are not well characterized by existing models, we calculate new models that compensate for topographic relief in order to derive improved estimates of surface properties. Areas investigated to date span from longitude 315 through 45, at all latitudes covered by Magellan. A survey of those areas yields preliminary results that suggest that topographically high regions are well suited to the current implementation of the Hagfors model. Striking examples of such large-scale good fits are Alpha Regio, the northern edges of Lada Terra, and the southern edge of Ishtar Terra. Other features that are typically well fit are the rims of coronae such as Heng-O and the peaks of volcanos such as Gula Mons. Surprisingly, topographically low regions, such as the ubiquitous plains areas, are modeled poorly in comparison. However, this generalization has has exceptions: Lakshmi Planum is an elevated region that is not well fit compared to the rest of neighboring Ishtar, while the southern parts of topographically low Guinevere Planitia are characterized quite well by the Hagfors model. Features that are candidates for improved models are impact craters, coronae, ridges of significant scale, complex ridged terrains, moderate-sized mountains, and sharp terrain boundaries. These features are chosen because the goodness of fit is likely to be most affected either by departures from normal incidence angles or by sharp changes in terrain type within a single footprint. Most large features that are elevated with respect to their surroundings will suffer from steep slope effects, and smaller coronae and impact craters will probably suffer due to rapid changes in their appearance within a single footprint (10-20 km).

Topographic controls on overland flow generation in a forest - An ensemble tree approach

NASA Astrophysics Data System (ADS)

Loos, Martin; Elsenbeer, Helmut

2011-10-01

SummaryOverland flow is an important hydrological pathway in many forests of the humid tropics. Its generation is subject to topographic controls at differing spatial scales. Our objective was to identify such controls on the occurrence of overland flow in a lowland tropical rainforest. To this end, we installed 95 overland flow detectors (OFDs) in four nested subcatchments of the Lutzito catchment on Barro Colorado Island, Panama, and monitored the frequency of overland flow occurrence during 18 rainfall events at each OFD location temporal frequency. For each such location, we derived three non-digital terrain attributes and 17 digital ones, of which 15 were based on Digital Elevation Models (DEMs) of three different resolutions. These attributes then served as input into a Random Forest ensemble tree model to elucidate the importance and partial and joint dependencies of topographic controls for overland flow occurrence. Lutzito features a high median temporal frequency in overland flow occurrence of 0.421 among OFD locations. However, spatial temporal frequencies of overland flow occurrence vary strongly among these locations and the subcatchments of Lutzito catchment. This variability is best explained by (1) microtopography, (2) coarse terrain sloping and (3) various measures of distance-to-channel, with the contribution of all other terrain attributes being small. Microtopographic features such as concentrated flowlines and wash areas produce highest temporal frequencies, whereas the occurrence of overland flow drops sharply for flow distances and terrain sloping beyond certain threshold values. Our study contributes to understanding both the spatial controls on overland flow generation and the limitations of terrain attributes for the spatially explicit prediction of overland flow frequencies.

Using a Budyko Derived Index to Evaluate the Internal Hydrological Variability of Catchments in Complex Terrain

NASA Astrophysics Data System (ADS)

Dominguez, M.

2017-12-01

Headwater catchments in complex terrain typically exhibit significant variations in microclimatic conditions across slopes. This microclimatic variability in turn, modifies land surface properties presumably altering the hydrologic dynamics of these catchments. The extent to which differences in microclimate and land cover dictate the partition of water and energy fluxes within a catchment is still poorly understood. In this study, we attempt to do an assessment of the effects of aspect, elevation and latitude (which are the principal factors that define microclimate conditions) on the hydrologic behavior of the hillslopes within catchments with complex terrain. Using a distributed hydrologic model on a number of catchments at different latitudes, where data is available for calibration and validation, we estimate the different components of the water balance to obtain the aridity index (AI = PET/P) and the evaporative index (EI = AET/P) of each slope for a number of years. We use Budyko's curve as a framework to characterize the inter-annual variability in the hydrologic response of the hillslopes in the studied catchments, developing a hydrologic sensitivity index (HSi) based on the relative change in Budyko's curve components (HSi=ΔAI/ΔEI). With this method, when the HSi values of a given hillslope are larger than 1 the hydrologic behavior of that part of the catchment is considered sensitive to changes in climatic conditions, while values approaching 0 would indicate the opposite. We use this approach as a diagnostic tool to discern the effect of aspect, elevation, and latitude on the hydrologic regime of the slopes in complex terrain catchments and to try to explain observed patterns of land cover conditions on these types of catchments.

A geomorphological seabed classification for the Weddell Sea, Antarctica

NASA Astrophysics Data System (ADS)

Jerosch, Kerstin; Kuhn, Gerhard; Krajnik, Ingo; Scharf, Frauke Katharina; Dorschel, Boris

2016-06-01

Sea floor morphology plays an important role in many scientific disciplines such as ecology, hydrology and sedimentology since geomorphic features can act as physical controls for e.g. species distribution, oceanographically flow-path estimations or sedimentation processes. In this study, we provide a terrain analysis of the Weddell Sea based on the 500 m × 500 m resolution bathymetry data provided by the mapping project IBCSO. Seventeen seabed classes are recognized at the sea floor based on a fine and broad scale Benthic Positioning Index calculation highlighting the diversity of the glacially carved shelf. Beside the morphology, slope, aspect, terrain rugosity and hillshade were calculated and supplied to the data archive PANGAEA. Applying zonal statistics to the geomorphic features identified unambiguously the shelf edge of the Weddell Sea with a width of 45-70 km and a mean depth of about 1200 m ranging from 270 m to 4300 m. A complex morphology of troughs, flat ridges, pinnacles, steep slopes, seamounts, outcrops, and narrow ridges, structures with approx. 5-7 km width, build an approx. 40-70 km long swath along the shelf edge. The study shows where scarps and depressions control the connection between shelf and abyssal and where high and low declination within the scarps e.g. occur. For evaluation purpose, 428 grain size samples were added to the seabed class map. The mean values of mud, sand and gravel of those samples falling into a single seabed class was calculated, respectively, and assigned to a sediment texture class according to a common sediment classification scheme.

A topographic feature taxonomy for a U.S. national topographic mapping ontology

USGS Publications Warehouse

Varanka, Dalia E.

2013-01-01

Using legacy feature lists from the U.S. National Topographic Mapping Program of the twentieth century, a taxonomy of features is presented for purposes of developing a national topographic feature ontology for geographic mapping and analysis. After reviewing published taxonomic classifications, six basic classes are suggested; terrain, surface water, ecological regimes, built-up areas, divisions, and events. Aspects of ontology development are suggested as the taxonomy is described.

Classification of earth terrain using polarimetric synthetic aperture radar images

NASA Technical Reports Server (NTRS)

Lim, H. H.; Swartz, A. A.; Yueh, H. A.; Kong, J. A.; Shin, R. T.; Van Zyl, J. J.

1989-01-01

Supervised and unsupervised classification techniques are developed and used to classify the earth terrain components from SAR polarimetric images of San Francisco Bay and Traverse City, Michigan. The supervised techniques include the Bayes classifiers, normalized polarimetric classification, and simple feature classification using discriminates such as the absolute and normalized magnitude response of individual receiver channel returns and the phase difference between receiver channels. An algorithm is developed as an unsupervised technique which classifies terrain elements based on the relationship between the orientation angle and the handedness of the transmitting and receiving polariation states. It is found that supervised classification produces the best results when accurate classifier training data are used, while unsupervised classification may be applied when training data are not available.

Lunae Planum

NASA Technical Reports Server (NTRS)

2002-01-01

(Released 24 June 2002) The Science This image is within a region called Lunae Planum, near 27.3N, 75.3W. This is a region west of the Viking 1 landing site that marks the transition between the Tharsis rise, a giant volcanic complex, and the northern lowland plains. The topographically high regions display numerous graben, signs of significant amounts of crustal deformation. The low areas display signs of resurfacing, including an unusual unit that appears to 'lap' onto the base of the uplands. This scarp follows the transition between the high and low areas throughout much of the image. It is not clear what caused these deposits, but a likely candidate is ice, which is suspected to have played a major role in the surface morphology of the fretted terrains and many features within the northern lowlands. The Story Lunae Planum was named after the Roman moon goddess Luna, who in ancient stories ruled over the night just as her counterpart, the sun god Sol, ruled over the day (a 'sol' is, in fact, the word used for a Martian day). Wearing the symbol of the crescent moon upon her head, Luna was known to ride on chariot pulled by two powerful horses. If the fictional Luna ever rode over the Martian plain named for her, she would find the terrain fairly rough going. You might say that she'd face a large number of 'ruts' on a geologic scale. That's because Lunae Planum marks the transition between the high Tharsis rise , a giant volcanic bulge on Mars, and the northern lowland plains. In this region, there are many signs of significant crustal deformation. Look for the dropped blocks of terrain called 'graben' on the higher surfaces in this image. Graben are created when tectonic forces tear apart the terrain, leaving long, large 'ruts' on the surface. We find graben on Earth too (think of Death Valley, the lowest dry land in the United States, or of the Jordan Dead Sea depression). Much more exciting than these depressions is the thin ridge that seems to lap up against the base of the uplands at the bottom of this image. While it's not clear what caused these deposits, ice is a likely candidate. Scientists have hypothesized that the mysterious systems of valleys and ridges (called 'fretted terrain') in this area were created through fractures and the collapse of large surface areas. Fretted terrain may have developed as icy debris flowed off of faulted valley walls and down onto the northern plains a long time ago in Martian history. This dramatic period would have coincided with the great Martian flood epoch, when melted ice from the subsurface was rapidly released in catastrophic amounts, carving out channels seen in other nearby regions. Lunae Planum lies west of Chryse Planitia (the Plains of Gold), where the Viking 1 spacecraft made history on July 20, 1976 as the first spacecraft to land safely on the surface of another planet. Viking Lander 1 made its final transmission to Earth on November 11, 1982. Perhaps one day a future spacecraft will settle down on this bright plain, using information collected by Odyssey today as the basis of its ground studies of this complex terrain. And who knows? Maybe even the design of a future rover could recall the image of a swiftly moving chariot, carrying the symbol of a crescent moon.

Ranging error analysis of single photon satellite laser altimetry under different terrain conditions

NASA Astrophysics Data System (ADS)

Huang, Jiapeng; Li, Guoyuan; Gao, Xiaoming; Wang, Jianmin; Fan, Wenfeng; Zhou, Shihong

2018-02-01

Single photon satellite laser altimeter is based on Geiger model, which has the characteristics of small spot, high repetition rate etc. In this paper, for the slope terrain, the distance of error's formula and numerical calculation are carried out. Monte Carlo method is used to simulate the experiment of different terrain measurements. The experimental results show that ranging accuracy is not affected by the spot size under the condition of the flat terrain, But the inclined terrain can influence the ranging error dramatically, when the satellite pointing angle is 0.001° and the terrain slope is about 12°, the ranging error can reach to 0.5m. While the accuracy can't meet the requirement when the slope is more than 70°. Monte Carlo simulation results show that single photon laser altimeter satellite with high repetition rate can improve the ranging accuracy under the condition of complex terrain. In order to ensure repeated observation of the same point for 25 times, according to the parameters of ICESat-2, we deduce the quantitative relation between the footprint size, footprint, and the frequency repetition. The related conclusions can provide reference for the design and demonstration of the domestic single photon laser altimetry satellite.

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.

Body-terrain interaction affects large bump traversal of insects and legged robots.

PubMed

Gart, Sean W; Li, Chen

2018-02-02

Small animals and robots must often rapidly traverse large bump-like obstacles when moving through complex 3D terrains, during which, in addition to leg-ground contact, their body inevitably comes into physical contact with the obstacles. However, we know little about the performance limits of large bump traversal and how body-terrain interaction affects traversal. To address these, we challenged the discoid cockroach and an open-loop six-legged robot to dynamically run into a large bump of varying height to discover the maximal traversal performance, and studied how locomotor modes and traversal performance are affected by body-terrain interaction. Remarkably, during rapid running, both the animal and the robot were capable of dynamically traversing a bump much higher than its hip height (up to 4 times the hip height for the animal and 3 times for the robot, respectively) at traversal speeds typical of running, with decreasing traversal probability with increasing bump height. A stability analysis using a novel locomotion energy landscape model explained why traversal was more likely when the animal or robot approached the bump with a low initial body yaw and a high initial body pitch, and why deflection was more likely otherwise. Inspired by these principles, we demonstrated a novel control strategy of active body pitching that increased the robot's maximal traversable bump height by 75%. Our study is a major step in establishing the framework of locomotion energy landscapes to understand locomotion in complex 3D terrains.

ARC-1979-AC79-7090

NASA Image and Video Library

1979-07-10

P-21762 C This color picture of Ganymede in the region 30° S 180° W shows features as small as 6 kilometers (3.7 miles) across. Shown is a bright halo impact crater that shows the fresh material thrown out of the crater. In the background is bright grooved terrain that may be the result of shearing of the surface materials along fault planes. The dark background material is the ancient heavily cratered terrain--the oldest material preserved on the Ganymede surface.

Lessons Learned from OSIRIS-Rex Autonomous Navigation Using Natural Feature Tracking

NASA Technical Reports Server (NTRS)

Lorenz, David A.; Olds, Ryan; May, Alexander; Mario, Courtney; Perry, Mark E.; Palmer, Eric E.; Daly, Michael

2017-01-01

The Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (Osiris-REx) spacecraft is scheduled to launch in September, 2016 to embark on an asteroid sample return mission. It is expected to rendezvous with the asteroid, Bennu, navigate to the surface, collect a sample (July 20), and return the sample to Earth (September 23). The original mission design called for using one of two Flash Lidar units to provide autonomous navigation to the surface. Following Preliminary design and initial development of the Lidars, reliability issues with the hardware and test program prompted the project to begin development of an alternative navigation technique to be used as a backup to the Lidar. At the critical design review, Natural Feature Tracking (NFT) was added to the mission. NFT is an onboard optical navigation system that compares observed images to a set of asteroid terrain models which are rendered in real-time from a catalog stored in memory on the flight computer. Onboard knowledge of the spacecraft state is then updated by a Kalman filter using the measured residuals between the rendered reference images and the actual observed images. The asteroid terrain models used by NFT are built from a shape model generated from observations collected during earlier phases of the mission and include both terrain shape and albedo information about the asteroid surface. As a result, the success of NFT is highly dependent on selecting a set of topographic features that can be both identified during descent as well as reliably rendered using the shape model data available. During development, the OSIRIS-REx team faced significant challenges in developing a process conducive to robust operation. This was especially true for terrain models to be used as the spacecraft gets close to the asteroid and higher fidelity models are required for reliable image correlation. This paper will present some of the challenges and lessons learned from the development of the NFT system which includes not just the flight hardware and software but the development of the terrain models used to generate the onboard rendered images.

Evaluation of the Operational Multi-scale Environment model with Grid Adaptivity (OMEGA) for use in Wind Energy Applications in the Great Basin of Nevada

NASA Astrophysics Data System (ADS)

King, Kristien C.

In order to further assess the wind energy potential for Nevada, the accuracy of a computational meteorological model, the Operational Multi-scale Environment model with Grid Adaptivity (OMEGA), was evaluated by comparing simulation results with data collected from a wind monitoring tower near Tonopah, NV. The state of Nevada is characterized by high mountains and low-lying valleys, therefore, in order to determine the wind potential for the state, meteorological models that predict the wind must be able to accurately represent and account for terrain features and simulate topographic forcing with accuracy. Topographic forcing has a dominant role in the development and modification of mesoscale flows in regions of complex terrain, like Tonopah, especially at the level of wind turbine blade heights (~80 m). Additionally, model factors such as horizontal resolution, terrain database resolution, model physics, time of model initialization, stability regime, and source of initial conditions may each affect the ability of a mesoscale model to forecast winds correctly. The observational tower used for comparison was located at Stone Cabin, Nevada. The tower had both sonic anemometers and cup anemometers installed at heights of 40 m, 60 m, and 80 m above the surface. During a previous experiment, tower data were collected for the period February 9 through March 10, 2007 and compared to model simulations using the MM5 and WRF models at a number of varying horizontal resolutions. In this previous research, neither the MM5 nor the WRF showed a significant improvement in ability to forecast wind speed with increasing horizontal grid resolution. The present research evaluated the ability of OMEGA to reproduce point winds as compared to the observational data from the Stone Cabin Tower at heights of 40 m, 60 m, and 80 m. Unlike other mesoscale atmospheric models, OMEGA incorporates an unstructured triangular adaptive grid which allows for increased flexibility and accuracy in characterizing areas of complex terrain. Model sensitivity to horizontal grid resolution, initial conditions, and time of initialization were tested. OMEGA was run over three different horizontal grid resolutions with minimum horizontal edge lengths of: 18 km, 6 km, and 2 km. For each resolution, the model was initialized using both the Global Forecasting System (GFS) and North American Regional Reanalysis (NARR) to determine model sensitivity to initial conditions. For both the NARR and GFS initializations, the model was started at both 0000 UTC and 1200 UTC to determine the effect of start time and stability regime on the performance of the model. An additional intensive study into the model's performance was also conducted by a detailed evaluation of model results during two separate 24-hour periods, the first a period where the model performed well and the second a period where the model performed poorly, to determine which atmospheric factors most affect the predictive ability of the OMEGA model. The statistical results were then compared with the results from the MM5 and WRF simulations to determine the most appropriate model for wind energy potential studies in complex terrain.

Terrain Extraction by Integrating Terrestrial Laser Scanner Data and Spectral Information

NASA Astrophysics Data System (ADS)

Lau, C. L.; Halim, S.; Zulkepli, M.; Azwan, A. M.; Tang, W. L.; Chong, A. K.

2015-10-01

The extraction of true terrain points from unstructured laser point cloud data is an important process in order to produce an accurate digital terrain model (DTM). However, most of these spatial filtering methods just utilizing the geometrical data to discriminate the terrain points from nonterrain points. The point cloud filtering method also can be improved by using the spectral information available with some scanners. Therefore, the objective of this study is to investigate the effectiveness of using the three-channel (red, green and blue) of the colour image captured from built-in digital camera which is available in some Terrestrial Laser Scanner (TLS) for terrain extraction. In this study, the data acquisition was conducted at a mini replica landscape in Universiti Teknologi Malaysia (UTM), Skudai campus using Leica ScanStation C10. The spectral information of the coloured point clouds from selected sample classes are extracted for spectral analysis. The coloured point clouds which within the corresponding preset spectral threshold are identified as that specific feature point from the dataset. This process of terrain extraction is done through using developed Matlab coding. Result demonstrates that a higher spectral resolution passive image is required in order to improve the output. This is because low quality of the colour images captured by the sensor contributes to the low separability in spectral reflectance. In conclusion, this study shows that, spectral information is capable to be used as a parameter for terrain extraction.

Atmospheric stability and complex terrain: comparing measurements and CFD

NASA Astrophysics Data System (ADS)

Koblitz, T.; Bechmann, A.; Berg, J.; Sogachev, A.; Sørensen, N.; Réthoré, P.-E.

2014-12-01

For wind resource assessment, the wind industry is increasingly relying on Computational Fluid Dynamics models that focus on modeling the airflow in a neutrally stratified surface layer. So far, physical processes that are specific to the atmospheric boundary layer, for example the Coriolis force, buoyancy forces and heat transport, are mostly ignored in state-of-the-art flow solvers. In order to decrease the uncertainty of wind resource assessment, the effect of thermal stratification on the atmospheric boundary layer should be included in such models. The present work focuses on non-neutral atmospheric flow over complex terrain including physical processes like stability and Coriolis force. We examine the influence of these effects on the whole atmospheric boundary layer using the DTU Wind Energy flow solver EllipSys3D. To validate the flow solver, measurements from Benakanahalli hill, a field experiment that took place in India in early 2010, are used. The experiment was specifically designed to address the combined effects of stability and Coriolis force over complex terrain, and provides a dataset to validate flow solvers. Including those effects into EllipSys3D significantly improves the predicted flow field when compared against the measurements.

Charon tectonics

PubMed Central

Beyer, Ross A.; Nimmo, Francis; McKinnon, William B.; Moore, Jeffrey M.; Binzel, Richard P.; Conrad, Jack W.; Cheng, Andy; Ennico, K.; Lauer, Tod R.; Olkin, C.B.; Robbins, Stuart; Schenk, Paul; Singer, Kelsi; Spencer, John R.; Stern, S. Alan; Weaver, H.A.; Young, L.A.; Zangari, Amanda M.

2017-01-01

New Horizons images of Pluto’s companion Charon show a variety of terrains that display extensional tectonic features, with relief surprising for this relatively small world. These features suggest a global extensional areal strain of order 1% early in Charon’s history. Such extension is consistent with the presence of an ancient global ocean, now frozen. PMID:28919640

Volunteers Help Decide Where to Point Mars Camera

NASA Image and Video Library

2015-07-22

This series of images from NASA's Mars Reconnaissance Orbiter successively zooms into "spider" features -- or channels carved in the surface in radial patterns -- in the south polar region of Mars. In a new citizen-science project, volunteers will identify features like these using wide-scale images from the orbiter. Their input will then help mission planners decide where to point the orbiter's high-resolution camera for more detailed views of interesting terrain. Volunteers will start with images from the orbiter's Context Camera (CTX), which provides wide views of the Red Planet. The first two images in this series are from CTX; the top right image zooms into a portion of the image at left. The top right image highlights the geological spider features, which are carved into the terrain in the Martian spring when dry ice turns to gas. By identifying unusual features like these, volunteers will help the mission team choose targets for the orbiter's High Resolution Imaging Science Experiment (HiRISE) camera, which can reveal more detail than any other camera ever put into orbit around Mars. The final image is this series (bottom right) shows a HiRISE close-up of one of the spider features. http://photojournal.jpl.nasa.gov/catalog/PIA19823

Preliminary geological mapping of Io

NASA Technical Reports Server (NTRS)

Masursky, H.; Schaber, G. G.; Soderblom, L. A.; Strom, R. G.

1979-01-01

A preliminary summary of information gained by Voyager 1 on the colored, terrain and landform surface units of Io and their global distribution is presented. Colored units are classified as white to bluish-white regions which may be sulfur or sulfur dioxide deposits, red, orange, or yellow regions thought to contain various sublimates or alterations of sulfur, brownish regions limited to the polar areas and dark brown areas surrounding some vents. Terrain features observed include plains broken by scarps, isolated mountainous regions and volcanic vents resembling terrestrial caldera or pit craters. Maps of the distribution of these features, compiled by photogeological mapping techniques developed for terrestrial volcanic mapping, are presented, and the implications of the surface unit distributions for the volcanology, crustal composition, internal convection patterns and surface age of Io are discussed.

CFD Prediction on the Pressure Distribution and Streamlines around an Isolated Single-Storey House Considering the Effect of Topographic Characteristics

NASA Astrophysics Data System (ADS)

Abdullah, J.; Zaini, S. S.; Aziz, M. S. A.; Majid, T. A.; Deraman, S. N. C.; Yahya, W. N. W.

2018-04-01

Single-storey houses are classified as low rise building and vulnerable to damages under windstorm event. This study was carried out with the aim to investigate the pressure distribution and streamlines around an isolated house by considering the effect of terrain characteristics. The topographic features such as flat, depression, ridge, and valley, are considered in this study. This simulation were analysed with Ansys FLUENT 14.0 software package. The result showed the topography characteristics influence the value of pressure coefficient and streamlines especially when the house was located at ridge terrain. The findings strongly suggested that wind analysis should include all topographic features in the analysis in order to establish the true wind force exerted on any structure.

Causes of accidents in terrain parks: an exploratory factor analysis of recreational freestylers' views.

PubMed

Carús, Luis

2014-03-01

This study examines ski and snowboard terrain park users' views on aspects associated with accidents by identifying and assessing variables that may influence the occurrence of accidents and the resulting injuries. The research was conducted in a major resort in the Spanish Pyrenees, using information gathered from freestyle skiers and snowboarders aged 6 or older. To identify interrelationships among variables and to group the variables belonging to unified concepts, an exploratory factor analysis was performed using varimax rotation. The results revealed 5 factors that grouped the measured variables that may influence the occurrence of accidents while freestyling in terrain parks. The park features, conditions of the activity, and the user's personal conditions were found to have the most substantial influence on the freestylers' perceptions. Variables identified as components of the main factors of accident risk in terrain parks should be incorporated into resort management communication and policies. © 2013 Wilderness Medical Society Published by Wilderness Medical Society All rights reserved.

A Height Estimation Approach for Terrain Following Flights from Monocular Vision.

PubMed

Campos, Igor S G; Nascimento, Erickson R; Freitas, Gustavo M; Chaimowicz, Luiz

2016-12-06

In this paper, we present a monocular vision-based height estimation algorithm for terrain following flights. The impressive growth of Unmanned Aerial Vehicle (UAV) usage, notably in mapping applications, will soon require the creation of new technologies to enable these systems to better perceive their surroundings. Specifically, we chose to tackle the terrain following problem, as it is still unresolved for consumer available systems. Virtually every mapping aircraft carries a camera; therefore, we chose to exploit this in order to use presently available hardware to extract the height information toward performing terrain following flights. The proposed methodology consists of using optical flow to track features from videos obtained by the UAV, as well as its motion information to estimate the flying height. To determine if the height estimation is reliable, we trained a decision tree that takes the optical flow information as input and classifies whether the output is trustworthy or not. The classifier achieved accuracies of 80 % for positives and 90 % for negatives, while the height estimation algorithm presented good accuracy.

Terra Meridiani

NASA Image and Video Library

2003-04-09

This image by NASA Mars Odyssey illustrates the complex terrains within Terra Meridiani. This general region is one of the more complex on Mars, with a rich array of sedimentary, volcanic, and impact surfaces that span a wide range of Martian history.

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.

Simulations of Turbulent Flow Over Complex Terrain Using an Immersed-Boundary Method

NASA Astrophysics Data System (ADS)

DeLeon, Rey; Sandusky, Micah; Senocak, Inanc

2018-02-01

We present an immersed-boundary method to simulate high-Reynolds-number turbulent flow over the complex terrain of Askervein and Bolund Hills under neutrally-stratified conditions. We reconstruct both the velocity and the eddy-viscosity fields in the terrain-normal direction to produce turbulent stresses as would be expected from the application of a surface-parametrization scheme based on Monin-Obukhov similarity theory. We find that it is essential to be consistent in the underlying assumptions for the velocity reconstruction and the eddy-viscosity relation to produce good results. To this end, we reconstruct the tangential component of the velocity field using a logarithmic velocity profile and adopt the mixing-length model in the near-surface turbulence model. We use a linear interpolation to reconstruct the normal component of the velocity to enforce the impermeability condition. Our approach works well for both the Askervein and Bolund Hills when the flow is attached to the surface, but shows slight disagreement in regions of flow recirculation, despite capturing the flow reversal.

Simulations of Turbulent Flow Over Complex Terrain Using an Immersed-Boundary Method

NASA Astrophysics Data System (ADS)

DeLeon, Rey; Sandusky, Micah; Senocak, Inanc

2018-06-01

We present an immersed-boundary method to simulate high-Reynolds-number turbulent flow over the complex terrain of Askervein and Bolund Hills under neutrally-stratified conditions. We reconstruct both the velocity and the eddy-viscosity fields in the terrain-normal direction to produce turbulent stresses as would be expected from the application of a surface-parametrization scheme based on Monin-Obukhov similarity theory. We find that it is essential to be consistent in the underlying assumptions for the velocity reconstruction and the eddy-viscosity relation to produce good results. To this end, we reconstruct the tangential component of the velocity field using a logarithmic velocity profile and adopt the mixing-length model in the near-surface turbulence model. We use a linear interpolation to reconstruct the normal component of the velocity to enforce the impermeability condition. Our approach works well for both the Askervein and Bolund Hills when the flow is attached to the surface, but shows slight disagreement in regions of flow recirculation, despite capturing the flow reversal.

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.

Optimal bipedal interactions with dynamic terrain: synthesis and analysis via nonlinear programming

NASA Astrophysics Data System (ADS)

Hubicki, Christian; Goldman, Daniel; Ames, Aaron

In terrestrial locomotion, gait dynamics and motor control behaviors are tuned to interact efficiently and stably with the dynamics of the terrain (i.e. terradynamics). This controlled interaction must be particularly thoughtful in bipeds, as their reduced contact points render them highly susceptible to falls. While bipedalism under rigid terrain assumptions is well-studied, insights for two-legged locomotion on soft terrain, such as sand and dirt, are comparatively sparse. We seek an understanding of how biological bipeds stably and economically negotiate granular media, with an eye toward imbuing those abilities in bipedal robots. We present a trajectory optimization method for controlled systems subject to granular intrusion. By formulating a large-scale nonlinear program (NLP) with reduced-order resistive force theory (RFT) models and jamming cone dynamics, the optimized motions are informed and shaped by the dynamics of the terrain. Using a variant of direct collocation methods, we can express all optimization objectives and constraints in closed-form, resulting in rapid solving by standard NLP solvers, such as IPOPT. We employ this tool to analyze emergent features of bipedal locomotion in granular media, with an eye toward robotic implementation.

Modeling and Simulation Architecture for Studying Doppler-Based Radar with Complex Environments

DTIC Science & Technology

2009-03-26

structures can interfere with a radar’s ability to detect moving aircraft because radar returns from turbines are comparable to those from slow flying...Netherlands Organisation for Applied Scientific Research . 13 EM Electromagnetic . . . . . . . . . . . . . . . . . . . . . . . 14 MTI Moving Target Indicator...ensure the turbine won’t interact with the radar. However, (2.3) doesn’t account for terrain masking or shadowing. If there is a tall object or terrain

Uncertainty modelling and analysis of volume calculations based on a regular grid digital elevation model (DEM)

NASA Astrophysics Data System (ADS)

Li, Chang; Wang, Qing; Shi, Wenzhong; Zhao, Sisi

2018-05-01

The accuracy of earthwork calculations that compute terrain volume is critical to digital terrain analysis (DTA). The uncertainties in volume calculations (VCs) based on a DEM are primarily related to three factors: 1) model error (ME), which is caused by an adopted algorithm for a VC model, 2) discrete error (DE), which is usually caused by DEM resolution and terrain complexity, and 3) propagation error (PE), which is caused by the variables' error. Based on these factors, the uncertainty modelling and analysis of VCs based on a regular grid DEM are investigated in this paper. Especially, how to quantify the uncertainty of VCs is proposed by a confidence interval based on truncation error (TE). In the experiments, the trapezoidal double rule (TDR) and Simpson's double rule (SDR) were used to calculate volume, where the TE is the major ME, and six simulated regular grid DEMs with different terrain complexity and resolution (i.e. DE) were generated by a Gauss synthetic surface to easily obtain the theoretical true value and eliminate the interference of data errors. For PE, Monte-Carlo simulation techniques and spatial autocorrelation were used to represent DEM uncertainty. This study can enrich uncertainty modelling and analysis-related theories of geographic information science.

Blades Across Pluto

NASA Image and Video Library

2016-03-31

The red outline in this global view of Pluto from NASA New Horizons marks the large area of mysterious, bladed terrain extending from the eastern section of the large feature informally named Tombaugh Regio.

Radar returns from ground clutter in vicinity of airports

NASA Technical Reports Server (NTRS)

Raemer, H. R.; Rahgavan, R.; Bhattacharya, A.

1988-01-01

The objective of this project is to develop a dynamic simulation of the received signals from natural and man-made ground features in the vicinity of airports. The simulation is run during landing and takeoff stages of a flight. Vugraphs of noteworthy features of the simulation, ground clutter data bases, the development of algorithms for terrain features, typical wave theory results, and a gravity wave height profile are given.

Preprocessing of SAR interferometric data using anisotropic diffusion filter

NASA Astrophysics Data System (ADS)

Sartor, Kenneth; Allen, Josef De Vaughn; Ganthier, Emile; Tenali, Gnana Bhaskar

2007-04-01

The most commonly used smoothing algorithms for complex data processing are blurring functions (i.e., Hanning, Taylor weighting, Gaussian, etc.). Unfortunately, the filters so designed blur the edges in a Synthetic Aperture Radar (SAR) scene, reduce the accuracy of features, and blur the fringe lines in an interferogram. For the Digital Surface Map (DSM) extraction, the blurring of these fringe lines causes inaccuracies in the height of the unwrapped terrain surface. Our goal here is to perform spatially non-uniform smoothing to overcome the above mentioned disadvantages. This is achieved by using a Complex Anisotropic Non-Linear Diffuser (CANDI) filter that is a spatially varying. In particular, an appropriate choice of the convection function in the CANDI filter is able to accomplish the non-uniform smoothing. This boundary sharpening intra-region smoothing filter acts on interferometric SAR (IFSAR) data with noise to produce an interferogram with significantly reduced noise contents and desirable local smoothing. Results of CANDI filtering will be discussed and compared with those obtained by using the standard filters on simulated data.

Concurrent planning and execution for a walking robot

NASA Astrophysics Data System (ADS)

Simmons, Reid

1990-07-01

The Planetary Rover project is developing the Ambler, a novel legged robot, and an autonomous software system for walking the Ambler over rough terrain. As part of the project, we have developed a system that integrates perception, planning, and real-time control to navigate a single leg of the robot through complex obstacle courses. The system is integrated using the Task Control Architecture (TCA), a general-purpose set of utilities for building and controlling distributed mobile robot systems. The walking system, as originally implemented, utilized a sequential sense-plan-act control cycle. This report describes efforts to improve the performance of the system by concurrently planning and executing steps. Concurrency was achieved by modifying the existing sequential system to utilize TCA features such as resource management, monitors, temporal constraints, and hierarchical task trees. Performance was increased in excess of 30 percent with only a relatively modest effort to convert and test the system. The results lend support to the utility of using TCA to develop complex mobile robot systems.

3D printing of soft robotic systems

NASA Astrophysics Data System (ADS)

Wallin, T. J.; Pikul, J.; Shepherd, R. F.

2018-06-01

Soft robots are capable of mimicking the complex motion of animals. Soft robotic systems are defined by their compliance, which allows for continuous and often responsive localized deformation. These features make soft robots especially interesting for integration with human tissues, for example, the implementation of biomedical devices, and for robotic performance in harsh or uncertain environments, for example, exploration in confined spaces or locomotion on uneven terrain. Advances in soft materials and additive manufacturing technologies have enabled the design of soft robots with sophisticated capabilities, such as jumping, complex 3D movements, gripping and releasing. In this Review, we examine the essential soft material properties for different elements of soft robots, highlighting the most relevant polymer systems. Advantages and limitations of different additive manufacturing processes, including 3D printing, fused deposition modelling, direct ink writing, selective laser sintering, inkjet printing and stereolithography, are discussed, and the different techniques are investigated for their application in soft robotic fabrication. Finally, we explore integrated robotic systems and give an outlook for the future of the field and remaining challenges.

High resolution imaging science experiment (HiRISE) images of volcanic terrains from the first 6 months of the Mars reconnaissance orbiter primary science phase

USGS Publications Warehouse

Keszthelyi, L.; Jaeger, W.; McEwen, A.; Tornabene, L.; Beyer, R.A.; Dundas, C.; Milazzo, M.

2008-01-01

In the first 6 months of the Mars Reconnaissance Orbiter's Primary Science Phase, the High Resolution Imaging Science Experiment (HiRISE) camera has returned images sampling the diversity of volcanic terrains on Mars. While many of these features were noted in earlier imaging, they are now seen with unprecedented clarity. We find that some volcanic vents produced predominantly effusive products while others generated mostly pyroclastics. Flood lavas were emplaced in both turbulent and gentle eruptions, producing roofed channels and inflation features. However, many areas on Mars are too heavily mantled to allow meter-scale volcanic features to be discerned. In particular, the major volcanic edifices are extensively mantled, though it is possible that some of the mantle is pyroclastic material rather than atmospheric dust. Support imaging by the Context Imager (CTX) and topographic information derived from stereo imaging are both invaluable in interpreting the HiRISE data. Copyright 2008 by the American Geophysical Union.

Optimization of radar imaging system parameters for geological analysis

NASA Technical Reports Server (NTRS)

Waite, W. P.; Macdonald, H. C.; Kaupp, V. H.

1981-01-01

The use of radar image simulation to model terrain variation and determine optimum sensor parameters for geological analysis is described. Optimum incidence angle is determined by the simulation, which evaluates separately the discrimination of surface features possible due to terrain geometry and that due to terrain scattering. Depending on the relative relief, slope, and scattering cross section, optimum incidence angle may vary from 20 to 80 degrees. Large incident angle imagery (more than 60 deg) is best for the widest range of geological applications, but in many cases these large angles cannot be achieved by satellite systems. Low relief regions require low incidence angles (less than 30 deg), so a satellite system serving a broad range of applications should have at least two selectable angles of incidence.

Miranda - 'Chevron' Grooves

NASA Technical Reports Server (NTRS)

1986-01-01

This image of Miranda, obtained by Voyager 2 on approach, shows an unusual 'chevron' figure and regions of distinctly differing terrain on the Uranian moon. Voyager was 42,000 kilometers (26,000 miles) away when its narrow-angle camera acquired this clear-filter view. Grooved areas baring light and dark bands, distinct from other areas of mottled terrain, are visible at this resolution of about 600 meters (2,000 feet). The bright V-shaped feature in the grooved areas is the 'chevron' observed in earlier, lower-resolution images. Cutting across the bands are sinuous scarps, probably faults. Superimposed on both types of terrain are many bowl-shaped impact craters less than 5 km (3 mi) wide. The entire picture spans an area about 220 km (140 mi) across. The Voyager project is managed for NASA by the Jet Propulsion Laboratory.

New Details on Pluto

NASA Image and Video Library

2015-07-10

This image of Pluto was taken by New Horizons' Long Range Reconnaissance Imager (LORRI) at 4:18 UT on July 9, 2015, from a range of 3.9 million miles (6.3 million kilometers). It reveals new details on the surface of Pluto, including complex patterns in the transition between the very dark equatorial band (nicknamed "the whale"), which occupies the lower part of the image, and the brighter northern terrain. The bright arc at the bottom of the disk shows that there is more bright terrain beyond the southern margin of the "whale." The side of Pluto that will be studied in great detail during the close encounter on July 14 is now rotating off the visible disk on the right hand side, and will not be seen again until shortly before closest approach. Three consecutive images were combined and sharpened, using a process called deconvolution, to create this view. Deconvolution enhances real detail but can also generate spurious features, including the bright edge seen on the upper and left margins of the disk (though the bright margin on the bottom of the disk is real). The wireframe globe shows the orientation of Pluto in the image: thicker lines indicate the equator and the prime meridian (the direction facing Charon). Central longitude on Pluto is 86°. http://photojournal.jpl.nasa.gov/catalog/PIA19705

A Novel Identification Methodology for the Coordinate Relationship between a 3D Vision System and a Legged Robot.

PubMed

Chai, Xun; Gao, Feng; Pan, Yang; Qi, Chenkun; Xu, Yilin

2015-04-22

Coordinate identification between vision systems and robots is quite a challenging issue in the field of intelligent robotic applications, involving steps such as perceiving the immediate environment, building the terrain map and planning the locomotion automatically. It is now well established that current identification methods have non-negligible limitations such as a difficult feature matching, the requirement of external tools and the intervention of multiple people. In this paper, we propose a novel methodology to identify the geometric parameters of 3D vision systems mounted on robots without involving other people or additional equipment. In particular, our method focuses on legged robots which have complex body structures and excellent locomotion ability compared to their wheeled/tracked counterparts. The parameters can be identified only by moving robots on a relatively flat ground. Concretely, an estimation approach is provided to calculate the ground plane. In addition, the relationship between the robot and the ground is modeled. The parameters are obtained by formulating the identification problem as an optimization problem. The methodology is integrated on a legged robot called "Octopus", which can traverse through rough terrains with high stability after obtaining the identification parameters of its mounted vision system using the proposed method. Diverse experiments in different environments demonstrate our novel method is accurate and robust.

Search for Impact Craters in the Volcanic and Volcano-Sedimentary Terrains of Mexico

NASA Astrophysics Data System (ADS)

Bartali, R.; Fucugauchi, J. U.

2011-12-01

It has long been recognized that the numbers of impact craters documented in the terrestrial record are small compared to those of the Moon and other planets and satellites. Processes acting on the Earth surface including tectonics, volcanism and erosion contribute to erase, modify and cover evidence of crater-forming impacts that have occurred through Earth's history. Even evidence on large impact structures is limited to few examples, with only three complex multi-ring structures so far recognized. Chicxulub is a ~200 km diameter multi-ring crater formed by an impact in the southern Gulf of Mexico about 65.5 Ma ago at the Cretaceous/Paleogene boundary. Chicxulub is the only impact structure documented in Mexico, Central and northern South America (http:www.unb.ca/passc/ImpactDatabase). Chicxulub, located in the Yucatan platform buried under a kilometer of carbonate rocks, was initially identified from its concentric semi-circular gravity and magnetic anomaly patterns. Yucatan peninsula has a low-relief topography and high contrasts in physical properties between carbonate rocks, impact lithologies and deformed target rocks. In contrast, most of the country has an abrupt topography with limited outcrops of Paleozoic and Precambrian terrains. The extensive igneous cover of the Sierra Madre Occidental, Trans-Mexican volcanic belt and Sierra Madre del Sur makes search for impact craters a difficult task. Early attempts were limited by the numerous volcanic craters and lack of high-resolution geophysical data. As part of a new country-wide search program, we have been conducting studies in northern Mexico using remote sensing and geophysical data to document circular and semi-circular crater-like features. The search has identified several structures, some well exposed and characterized by simple crater morphologies and topographic rims. These landforms have been mapped, estimating their dimensions, distribution and characterizing the surrounding terrains. Aeromagnetic anomaly data from low-altitude surveys have been used to characterize the structures, together with geological and topographic maps. For the promising sites, low altitude aerial images and on-site reconnaissance surveys and sampling are completed. Sites studied include isolated structures built on low relief terrains as well as multiple crater-like structures on volcanic terrains. Here we present initial results of the project in the Chihuahua region and discuss the methods, findings and difficulties in identification of impact structures.

Crustal Evolution of the Protonilus Mensae Area, Mars

NASA Technical Reports Server (NTRS)

McGill, G. E.; Smrekar, S. E.; Dimitriou, A. M.; Raymond, C. A.

2004-01-01

Despite research by numerous geologists and geo- physicists, the age and origin of the martian crustal dichotomy remain uncertain. Models for the origin of this dichotomy involve single or multiple impact, mantle megaplumes, primordial crustal asymmetry, and plate tectonics. Most of these models imply a Noachian age for the dichotomy. A major problem common to all genetic models is the difficulty separating the features resulting from the primary cause for the dichotomy from features due to younger fault- ing, impact cratering, volcanism, deposition, and erosion. highlands (the dichotomy boundary) approximates a small circle that ranges in latitude from about -10 deg. in Elysium Planitia to about +45 deg. north of Arabia Terra. For much of its length the boundary is characterized by relatively steep scarps separating highland plateau to the south from lowland plains to the north, generally with a complex transition zone on the lowland side of these scarps. These scarps are almost certainly due to normal faulting. The type fretted terrain, which defines the boundary in north-central Arabia Terra, also is characterized by scarps but has under- gone a more complex history of faulting and dissection [13]. In some places, notably in the Acidalia Planitia region, the dichotomy boundary is gradational. In the Tharsis region the boundary is obscured by younger volcanics.

Lidar ceilometer observations and modeling of a fireworks plume in Vancouver, British Columbia

NASA Astrophysics Data System (ADS)

van der Kamp, Derek; McKendry, Ian; Wong, May; Stull, Roland

Observations of a plume emanating from a 30-min duration pyrotechnic display with a lidar ceilometer are described for an urban setting in complex, coastal terrain. Advection of the plume across the ceilometer occurred at a mean height of 250 m AGL. The plume traveled downwind at ˜3 m s -1, and at a distance of 8 km downwind, was ˜100 m in vertical thickness with particulate matter (PM) concentrations of order 30-40 μg m -3. Surface PM observations from surrounding urban monitoring stations suggest that the plume was not mixed to ground over the urban area. Plume trajectories at ˜250 m simulated by three numerical models all traveled to the northeast of the ceilometer location. Horizontal plume dispersion estimates suggest that the model trajectories were too far north to accommodate the likely lateral plume spread necessary to explain the ceilometer observations. This poor agreement between near surface observations and model output is consistent with previous mesoscale model validations in this region of complex urbanized terrain, and suggests that despite improvements in mesoscale model resolution, there remains an urgent need to improve upstream initial conditions over the Pacific Ocean, data assimilation over complex terrain, the representation of urban areas in mesoscale models, and to further validate such models for nocturnal applications in complex settings.

GIS Toolsets for Planetary Geomorphology and Landing-Site Analysis

NASA Astrophysics Data System (ADS)

Nass, Andrea; van Gasselt, Stephan

2015-04-01

Modern Geographic Information Systems (GIS) allow expert and lay users alike to load and position geographic data and perform simple to highly complex surface analyses. For many applications dedicated and ready-to-use GIS tools are available in standard software systems while other applications require the modular combination of available basic tools to answer more specific questions. This also applies to analyses in modern planetary geomorphology where many of such (basic) tools can be used to build complex analysis tools, e.g. in image- and terrain model analysis. Apart from the simple application of sets of different tools, many complex tasks require a more sophisticated design for storing and accessing data using databases (e.g. ArcHydro for hydrological data analysis). In planetary sciences, complex database-driven models are often required to efficiently analyse potential landings sites or store rover data, but also geologic mapping data can be efficiently stored and accessed using database models rather than stand-alone shapefiles. For landings-site analyses, relief and surface roughness estimates are two common concepts that are of particular interest and for both, a number of different definitions co-exist. We here present an advanced toolset for the analysis of image and terrain-model data with an emphasis on extraction of landing site characteristics using established criteria. We provide working examples and particularly focus on the concepts of terrain roughness as it is interpreted in geomorphology and engineering studies.

Intercomparison of cosmic-ray neutron sensors and water balance monitoring in an urban environment

NASA Astrophysics Data System (ADS)

Schrön, Martin; Zacharias, Steffen; Womack, Gary; Köhli, Markus; Desilets, Darin; Oswald, Sascha E.; Bumberger, Jan; Mollenhauer, Hannes; Kögler, Simon; Remmler, Paul; Kasner, Mandy; Denk, Astrid; Dietrich, Peter

2018-03-01

Sensor-to-sensor variability is a source of error common to all geoscientific instruments that needs to be assessed before comparative and applied research can be performed with multiple sensors. Consistency among sensor systems is especially critical when subtle features of the surrounding terrain are to be identified. Cosmic-ray neutron sensors (CRNSs) are a recent technology used to monitor hectometre-scale environmental water storages, for which a rigorous comparison study of numerous co-located sensors has not yet been performed. In this work, nine stationary CRNS probes of type CRS1000 were installed in relative proximity on a grass patch surrounded by trees, buildings, and sealed areas. While the dynamics of the neutron count rates were found to be similar, offsets of a few percent from the absolute average neutron count rates were found. Technical adjustments of the individual detection parameters brought all instruments into good agreement. Furthermore, we found a critical integration time of 6 h above which all sensors showed consistent dynamics in the data and their RMSE fell below 1 % of gravimetric water content. The residual differences between the nine signals indicated local effects of the complex urban terrain on the scale of several metres. Mobile CRNS measurements and spatial simulations with the URANOS neutron transport code in the surrounding area (25 ha) have revealed substantial sub-footprint heterogeneity to which CRNS detectors are sensitive despite their large averaging volume. The sealed and constantly dry structures in the footprint furthermore damped the dynamics of the CRNS-derived soil moisture. We developed strategies to correct for the sealed-area effect based on theoretical insights about the spatial sensitivity of the sensor. This procedure not only led to reliable soil moisture estimation during dry-out periods, it further revealed a strong signal of intercepted water that emerged over the sealed surfaces during rain events. The presented arrangement offered a unique opportunity to demonstrate the CRNS performance in complex terrain, and the results indicated great potential for further applications in urban climate research.

Impact of land surface conditions on the predictability of hydrologic processes and mountain-valley circulations in the North American Monsoon region

NASA Astrophysics Data System (ADS)

Xiang, T.; Vivoni, E. R.; Gochis, D. J.; Mascaro, G.

2015-12-01

Heterogeneous land surface conditions are essential components of land-atmosphere interactions in regions of complex terrain and have the potential to affect convective precipitation formation. Yet, due to their high complexity, hydrologic processes over mountainous regions are not well understood, and are usually parameterized in simple ways within coupled land-atmosphere modeling frameworks. With the improving model physics and spatial resolution of numerical weather prediction models, there is an urgent need to understand how land surface processes affect local and regional meteorological processes. In the North American Monsoon (NAM) region, the summer rainy season is accompanied by a dramatic greening of mountain ecosystems that adds spatiotemporal variability in vegetation which is anticipated to impact the conditions leading to convection, mountain-valley circulations and mesoscale organization. In this study, we present results from a detailed analysis of a high-resolution (1 km) land surface model, Noah-MP, in a large, mountainous watershed of the NAM region - the Rio Sonora (21,264 km2) in Mexico. In addition to capturing the spatial variations in terrain and soil distributions, recently-developed features in Noah-MP allow the model to read time-varying vegetation parameters derived from remotely-sensed vegetation indices; however, this new implementation has not been fully evaluated. Therefore, we assess the simulated spatiotemporal fields of soil moisture, surface temperature and surface energy fluxes through comparisons to remote sensing products and results from coarser land surface models obtained from the North American Land Data Assimilation System. We focus attention on the impact of vegetation changes along different elevation bands on the diurnal cycle of surface energy fluxes to provide a baseline for future analyses of mountain-valley circulations using a coupled land-atmosphere modeling system. Our study also compares limited streamflow observations in the large watershed to simulations using the terrain and channel routing when Noah-MP is run within the WRF-Hydro modeling framework, with the goals of validating the rainfall-runoff partitioning and translating the spatiotemporal mountain processes into improvements in streamflow predictions.

A Description of Sub-Equatorial Volcanic Structures Consistent with Sub-Ice Magmatism East of Nepenthes Mensae, Mars.

NASA Astrophysics Data System (ADS)

Caprarelli, G.; de Pablo Hernandez, M. A.

2014-12-01

The Martian region located immediately north of the dichotomy scarp, between latitudes 120°E and 135°E, is covered by fretted terrains, characterised by the presence of knobs and mesas formed by eroded and reworked material of highlands provenance, and the smoother terrains between them [1]. Topographic depressions of oblong shape, generally parallel to the scarp, of rough and chaotic appearance, are also observed. The high resolution (~ 6 m/pixel, [2]) Context Camera (CTX) on board Mars Reconnaissance Orbiter (MRO) makes it possible to examine the morphologies of these topographic depressions in great detail, unveiling their complex geological histories. Here we expand on our earlier work in the adjacent Nepenthes Mensae region [3] and present the results of our observations of morphologies of likely igneous origin. We identified a variety of shapes consistent with magmatic structures and constructs: dikes, collapsed lava tubes, and lava flows are observable in the smoother terrains. Most of the elevated structures in the areas are strongly eroded knobs and mesas covered by dust and debris. In some cases however, the morphological characteristics of 2-10 km-size structures are clear and sharp, which allowed us to identify features consistent with sub-ice volcanic constructs, such as tuyas and tindars [4]. Geological reconstructions involving magma-ice interaction are supported by the presence of lobate aprons around knobs and mesas, and of scalloped ejecta surrounding complex impact craters, suggesting the existence of ice both underground and on the surface of these low elevation areas at the time of formation of these constructs. [1] Tanaka et al. (2005) Geologic Map of the Northern Plains of Mars. USGS SIM 2888. [2] Malin et al. (2007) Context Camera investigation on board the Mars Reconnaissance Orbiter. JGR 112, E05S04, 10.1029/2006JE002808. [3] dePablo and Caprarelli (2010) Possible subglacial volcanoes in Nepenthes Mensae, eastern hemisphere, Mars. LPSC 41, 1584. [4] Jakobsson and Gudmundsson (2008) Subglacial and intraglacial volcanic formations in Iceland. Jökull 58, 179-196.

Simulating Complex, Cold-region Process Interactions Using a Multi-scale, Variable-complexity Hydrological Model

NASA Astrophysics Data System (ADS)

Marsh, C.; Pomeroy, J. W.; Wheater, H. S.

2017-12-01

Accurate management of water resources is necessary for social, economic, and environmental sustainability worldwide. In locations with seasonal snowcovers, the accurate prediction of these water resources is further complicated due to frozen soils, solid-phase precipitation, blowing snow transport, and snowcover-vegetation-atmosphere interactions. Complex process interactions and feedbacks are a key feature of hydrological systems and may result in emergent phenomena, i.e., the arising of novel and unexpected properties within a complex system. One example is the feedback associated with blowing snow redistribution, which can lead to drifts that cause locally-increased soil moisture, thus increasing plant growth that in turn subsequently impacts snow redistribution, creating larger drifts. Attempting to simulate these emergent behaviours is a significant challenge, however, and there is concern that process conceptualizations within current models are too incomplete to represent the needed interactions. An improved understanding of the role of emergence in hydrological systems often requires high resolution distributed numerical hydrological models that incorporate the relevant process dynamics. The Canadian Hydrological Model (CHM) provides a novel tool for examining cold region hydrological systems. Key features include efficient terrain representation, allowing simulations at various spatial scales, reduced computational overhead, and a modular process representation allowing for an alternative-hypothesis framework. Using both physics-based and conceptual process representations sourced from long term process studies and the current cold regions literature allows for comparison of process representations and importantly, their ability to produce emergent behaviours. Examining the system in a holistic, process-based manner can hopefully derive important insights and aid in development of improved process representations.

Sculpting Mountains: Interactive Terrain Modeling Based on Subsurface Geology.

PubMed

Cordonnier, Guillaume; Cani, Marie-Paule; Benes, Bedrich; Braun, Jean; Galin, Eric

2018-05-01

Most mountain ranges are formed by the compression and folding of colliding tectonic plates. Subduction of one plate causes large-scale asymmetry while their layered composition (or stratigraphy) explains the multi-scale folded strata observed on real terrains. We introduce a novel interactive modeling technique to generate visually plausible, large scale terrains that capture these phenomena. Our method draws on both geological knowledge for consistency and on sculpting systems for user interaction. The user is provided hands-on control on the shape and motion of tectonic plates, represented using a new geologically-inspired model for the Earth crust. The model captures their volume preserving and complex folding behaviors under collision, causing mountains to grow. It generates a volumetric uplift map representing the growth rate of subsurface layers. Erosion and uplift movement are jointly simulated to generate the terrain. The stratigraphy allows us to render folded strata on eroded cliffs. We validated the usability of our sculpting interface through a user study, and compare the visual consistency of the earth crust model with geological simulation results and real terrains.

Toward autonomous driving: The CMU Navlab. I - Perception

NASA Technical Reports Server (NTRS)

Thorpe, Charles; Hebert, Martial; Kanade, Takeo; Shafer, Steven

1991-01-01

The Navlab project, which seeks to build an autonomous robot that can operate in a realistic environment with bad weather, bad lighting, and bad or changing roads, is discussed. The perception techniques developed for the Navlab include road-following techniques using color classification and neural nets. These are discussed with reference to three road-following systems, SCARF, YARF, and ALVINN. Three-dimensional perception using three types of terrain representation (obstacle maps, terrain feature maps, and high-resolution maps) is examined. It is noted that perception continues to be an obstacle in developing autonomous vehicles.

An Assessment of Wind Plant Complex Flows Using Advanced Doppler Radar Measurements

NASA Astrophysics Data System (ADS)

Gunter, W. S.; Schroeder, J.; Hirth, B.; Duncan, J.; Guynes, J.

2015-12-01

As installed wind energy capacity continues to steadily increase, the need for comprehensive measurements of wind plant complex flows to further reduce the cost of wind energy has been well advertised by the industry as a whole. Such measurements serve diverse perspectives including resource assessment, turbine inflow and power curve validation, wake and wind plant layout model verification, operations and maintenance, and the development of future advanced wind plant control schemes. While various measurement devices have been matured for wind energy applications (e.g. meteorological towers, LIDAR, SODAR), this presentation will focus on the use of advanced Doppler radar systems to observe the complex wind flows within and surrounding wind plants. Advanced Doppler radars can provide the combined advantage of a large analysis footprint (tens of square kilometers) with rapid data analysis updates (a few seconds to one minute) using both single- and dual-Doppler data collection methods. This presentation demonstrates the utility of measurements collected by the Texas Tech University Ka-band (TTUKa) radars to identify complex wind flows occurring within and nearby operational wind plants, and provide reliable forecasts of wind speeds and directions at given locations (i.e. turbine or instrumented tower sites) 45+ seconds in advance. Radar-derived wind maps reveal commonly observed features such as turbine wakes and turbine-to-turbine interaction, high momentum wind speed channels between turbine wakes, turbine array edge effects, transient boundary layer flow structures (such as wind streaks, frontal boundaries, etc.), and the impact of local terrain. Operational turbine or instrumented tower data are merged with the radar analysis to link the observed complex flow features to turbine and wind plant performance.

Complex Environmental Data Modelling Using Adaptive General Regression Neural Networks

NASA Astrophysics Data System (ADS)

Kanevski, Mikhail

2015-04-01

The research deals with an adaptation and application of Adaptive General Regression Neural Networks (GRNN) to high dimensional environmental data. GRNN [1,2,3] are efficient modelling tools both for spatial and temporal data and are based on nonparametric kernel methods closely related to classical Nadaraya-Watson estimator. Adaptive GRNN, using anisotropic kernels, can be also applied for features selection tasks when working with high dimensional data [1,3]. In the present research Adaptive GRNN are used to study geospatial data predictability and relevant feature selection using both simulated and real data case studies. The original raw data were either three dimensional monthly precipitation data or monthly wind speeds embedded into 13 dimensional space constructed by geographical coordinates and geo-features calculated from digital elevation model. GRNN were applied in two different ways: 1) adaptive GRNN with the resulting list of features ordered according to their relevancy; and 2) adaptive GRNN applied to evaluate all possible models N [in case of wind fields N=(2^13 -1)=8191] and rank them according to the cross-validation error. In both cases training were carried out applying leave-one-out procedure. An important result of the study is that the set of the most relevant features depends on the month (strong seasonal effect) and year. The predictabilities of precipitation and wind field patterns, estimated using the cross-validation and testing errors of raw and shuffled data, were studied in detail. The results of both approaches were qualitatively and quantitatively compared. In conclusion, Adaptive GRNN with their ability to select features and efficient modelling of complex high dimensional data can be widely used in automatic/on-line mapping and as an integrated part of environmental decision support systems. 1. Kanevski M., Pozdnoukhov A., Timonin V. Machine Learning for Spatial Environmental Data. Theory, applications and software. EPFL Press. With a CD: data, software, guides. (2009). 2. Kanevski M. Spatial Predictions of Soil Contamination Using General Regression Neural Networks. Systems Research and Information Systems, Volume 8, number 4, 1999. 3. Robert S., Foresti L., Kanevski M. Spatial prediction of monthly wind speeds in complex terrain with adaptive general regression neural networks. International Journal of Climatology, 33 pp. 1793-1804, 2013.

Geologic mapping of Northern Atla Regio on Venus: Preliminary data

NASA Technical Reports Server (NTRS)

Nikishin, A. M.; Burba, G. A.

1993-01-01

The Northern part of Atla Regio within the frame of C1-formate Magellan photo map 15N197 was mapped geologically at scale 1:8,000,000. This is a part of Russia's contribution into C1 geologic mapping efforts. The map is reproduced here being reduced about twice. The map shows that the Northern Atla area is predominantly a volcanic plain with numerous volcanic features: shield volcanoes, domes and hills with various morphology, corona-like constructions, radar bright and dark spots often with flow-like outlines. Relatively small areas of tessera occurred in the area are mainly semi-flooded with the plain material. Tesserae are considered to be the oldest terrains within the map sheet. There are many lineated terrains in the region. They are interpreted as the old, almost-buried tesserae (those with crossed lineaments) or partly buried ridge belts (those with parallel lineaments). These lineated terrains have an intermediate age between the young volcanic plains and the old tessera areas. Two prominent high volcanic shields are located within the region - Ozza Mons and Sapas Mona. The most prominent structure in Northern Atla is Ganis Chasma rift. The rift cuts volcanic plain and is considered to be under formation during approximately the same time with Ozza Mons shield. Ganis Chasma rift valley is highly fractured and bounded with fault scarps. Rift shoulder uplifts are typical for Ganis Chasma. There are few relatively young volcanic features inside the rift valley. The analysis of fracturing and rift valley geometry shows the rift originated due to 5-10 percent crustal extention followed by the crustal subsidence. The age sequence summary for the main terrain types in the region is (from older to younger ones): tesserae; lineated terrains with crossed lineaments; lineated terrains with parallel lineaments; volcanic plains; and prominent volcanic shields and Ganis Chasma rift valley. The geologic structure of Atla Regio as it appeared now with the Magellan high resolution images is very close to that of Beta Regio. Such conclusion coincide with the earlier ones based on the coarser data.

Textures in Arcadia Planitia

NASA Image and Video Library

2003-03-07

An unusual mix of textures is featured in this image from NASA Mars Odyssey spacecraft of a surface east of the Phlegra Montes. Scabby mounds, commonly occurring around degraded craters, mix with a more muted, knobby terrain.

Western USA

Atmospheric Science Data Center

2014-05-15

... Terrain Elevation Model from the United States Geological Survey. Among the prominent features are the snow-capped Rocky Mountains ... is part of NASA's Earth Science Enterprise, a long-term research and technology program designed to examine Earth's land, oceans, ...

Europa Ice

NASA Image and Video Library

1998-05-08

This image of Jupiter icy satellite Europa shows surface features such as domes and ridges, as well as a region of disrupted terrain including crustal plates which are thought to have broken apart and rafted into new positions.

Numerical simulation of terrain-induced mesoscale circulation in the Chiang Mai area, Thailand

NASA Astrophysics Data System (ADS)

Sathitkunarat, Surachai; Wongwises, Prungchan; Pan-Aram, Rudklao; Zhang, Meigen

2008-11-01

The regional atmospheric modeling system (RAMS) was applied to Chiang Mai province, a mountainous area in Thailand, to study terrain-induced mesoscale circulations. Eight cases in wet and dry seasons under different weather conditions were analyzed to show thermal and dynamic impacts on local circulations. This is the first study of RAMS in Thailand especially investigating the effect of mountainous area on the simulated meteorological data. Analysis of model results indicates that the model can reproduce major features of local circulation and diurnal variations in temperatures. For evaluating the model performance, model results were compared with observed wind speed, wind direction, and temperature monitored at a meteorological tower. Comparison shows that the modeled values are generally in good agreement with observations and that the model captured many of the observed features.

Pluto's Surface in Detail

NASA Image and Video Library

2017-07-14

On July 14, 2015, NASA's New Horizons spacecraft made its historic flight through the Pluto system. This detailed, high-quality global mosaic of Pluto was assembled from nearly all of the highest-resolution images obtained by the Long-Range Reconnaissance Imager (LORRI) and the Multispectral Visible Imaging Camera (MVIC) on New Horizons. The mosaic is the most detailed and comprehensive global view yet of Pluto's surface using New Horizons data. It includes topography data of the hemisphere visible to New Horizons during the spacecraft's closest approach. The topography is derived from digital stereo-image mapping tools that measure the parallax -- or the difference in the apparent relative positions -- of features on the surface obtained at different viewing angles during the encounter. Scientists use these parallax displacements of high and low terrain to estimate landform heights. The global mosaic has been overlain with transparent, colorized topography data wherever on the surface stereo data is available. Terrain south of about 30°S was in darkness leading up to and during the flyby, so is shown in black. Examples of large-scale topographic features on Pluto include the vast expanse of very flat, low-elevation nitrogen ice plains of Sputnik Planitia ("P") -- note that all feature names in the Pluto system are informal -- and, on the eastern edge of the encounter hemisphere, the aligned, high-elevation ridges of Tartarus Dorsa ("T") that host the enigmatic bladed terrain, mountains, possible cryovolcanos, canyons, craters and more. https://photojournal.jpl.nasa.gov/catalog/PIA21861

Dissolution-Enlarged Fractures Imaging Using Electrical Resistivity Tomography (ERT)

NASA Astrophysics Data System (ADS)

Siami-Irdemoosa, Elnaz

In recent years the electrical imaging techniques have been largely applied to geotechnical and environmental investigations. These techniques have proven to be the best geophysical methods for site investigations in karst terrain, particularly when the overburden soil is clay-dominated. Karst is terrain with a special landscape and distinctive hydrological system developed by dissolution of rocks, particularly carbonate rocks such as limestone and dolomite, made by enlarging fractures into underground conduits that can enlarge into caverns, and in some cases collapse to form sinkholes. Bedding planes, joints, and faults are the principal structural guides for underground flow and dissolution in almost all karstified rocks. Despite the important role of fractures in karst development, the geometry of dissolution-enlarged fractures remain poorly unknown. These features are characterized by an strong contrast with the surrounding formations in terms of physical properties, such as electrical resistivity. Electrical resistivity tomography (ERT) was used as the primary geophysical tool to image the subsurface in a karst terrain in Greene County, Missouri. Pattern, orientation and density of the joint sets were interpreted from ERT data in the investigation site. The Multi-channel Analysis of Surface Wave (MASW) method and coring were employed to validate the interpretation results. Two sets of orthogonal visually prominent joints have been identified in the investigation site: north-south trending joint sets and west-east trending joint sets. However, most of the visually prominent joint sets are associated with either cultural features that concentrate runoff, natural surface drainage features or natural surface drainage.

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

NASA Astrophysics Data System (ADS)

Fang, Jiannong; Porté-Agel, Fernando

2016-09-01

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

Digital soil mapping using remote sensing indices, terrain attributes, and vegetation features in the rangelands of northeastern Iran.

PubMed

Mahmoudabadi, Ebrahim; Karimi, Alireza; Haghnia, Gholam Hosain; Sepehr, Adel

2017-09-11

Digital soil mapping has been introduced as a viable alternative to the traditional mapping methods due to being fast and cost-effective. The objective of the present study was to investigate the capability of the vegetation features and spectral indices as auxiliary variables in digital soil mapping models to predict soil properties. A region with an area of 1225 ha located in Bajgiran rangelands, Khorasan Razavi province, northeastern Iran, was chosen. A total of 137 sampling sites, each containing 3-5 plots with 10-m interval distance along a transect established based on randomized-systematic method, were investigated. In each plot, plant species names and numbers as well as vegetation cover percentage (VCP) were recorded, and finally one composite soil sample was taken from each transect at each site (137 soil samples in total). Terrain attributes were derived from a digital elevation model, different bands and spectral indices were obtained from the Landsat7 ETM+ images, and vegetation features were calculated in the plots, all of which were used as auxiliary variables to predict soil properties using artificial neural network, gene expression programming, and multivariate linear regression models. According to R 2 RMSE and MBE values, artificial neutral network was obtained as the most accurate soil properties prediction function used in scorpan model. Vegetation features and indices were more effective than remotely sensed data and terrain attributes in predicting soil properties including calcium carbonate equivalent, clay, bulk density, total nitrogen, carbon, sand, silt, and saturated moisture capacity. It was also shown that vegetation indices including NDVI, SAVI, MSAVI, SARVI, RDVI, and DVI were more effective in estimating the majority of soil properties compared to separate bands and even some soil spectral indices.

Acidalia Planitia

NASA Technical Reports Server (NTRS)

2002-01-01

[figure removed for brevity, see original site] (Released 25 July 2002) The lineations seen in this THEMIS visible image occur in Acidalia Planitia, and create what is referred to as 'patterned ground' or 'polygonal terrain.' The lineations are fissures, or cracks in the ground and are possibly evidence that there was once subsurface ice or water in the region. On Earth, similar features occur when ice or water is removed from the subsurface. The removal of material causes the ground to slump, and the surface expression of this slumping is the presence of these fissures, which tend to align themselves along common orientations, and in some cases, into polygonal shapes. There are other hypotheses, not all of which involve liquid or frozen water, regarding the formation of patterned ground. Desiccation of wet soils on Earth forms mud cracks, which are similar in appearance to the martian features, but occur on a much smaller scale. Alternatively, oriented cracks form when lava flows cool. The cracks formed by this process would be on about the same scale as those seen in this image. The best example of polygonal terrain occurs about halfway down the image. The largest fractures, as in other places in the image, run from the lower left to the upper right of the image. In some cases, though, smaller fractures occur in other orientations, creating the polygonal terrain. Scientists have been aware of these features on the surface of Mars since the Viking era, but the THEMIS visible camera will allow scientists to map these features at higher resolution with more coverage over the high latitude regions where they are most common, perhaps giving further insight into the mechanism(s) of their formation.

A Unified Analysis of Structured Sonar-terrain Data using Bayesian Functional Mixed Models.

PubMed

Zhu, Hongxiao; Caspers, Philip; Morris, Jeffrey S; Wu, Xiaowei; Müller, Rolf

2018-01-01

Sonar emits pulses of sound and uses the reflected echoes to gain information about target objects. It offers a low cost, complementary sensing modality for small robotic platforms. While existing analytical approaches often assume independence across echoes, real sonar data can have more complicated structures due to device setup or experimental design. In this paper, we consider sonar echo data collected from multiple terrain substrates with a dual-channel sonar head. Our goals are to identify the differential sonar responses to terrains and study the effectiveness of this dual-channel design in discriminating targets. We describe a unified analytical framework that achieves these goals rigorously, simultaneously, and automatically. The analysis was done by treating the echo envelope signals as functional responses and the terrain/channel information as covariates in a functional regression setting. We adopt functional mixed models that facilitate the estimation of terrain and channel effects while capturing the complex hierarchical structure in data. This unified analytical framework incorporates both Gaussian models and robust models. We fit the models using a full Bayesian approach, which enables us to perform multiple inferential tasks under the same modeling framework, including selecting models, estimating the effects of interest, identifying significant local regions, discriminating terrain types, and describing the discriminatory power of local regions. Our analysis of the sonar-terrain data identifies time regions that reflect differential sonar responses to terrains. The discriminant analysis suggests that a multi- or dual-channel design achieves target identification performance comparable with or better than a single-channel design.

A Unified Analysis of Structured Sonar-terrain Data using Bayesian Functional Mixed Models

PubMed Central

Zhu, Hongxiao; Caspers, Philip; Morris, Jeffrey S.; Wu, Xiaowei; Müller, Rolf

2017-01-01

Sonar emits pulses of sound and uses the reflected echoes to gain information about target objects. It offers a low cost, complementary sensing modality for small robotic platforms. While existing analytical approaches often assume independence across echoes, real sonar data can have more complicated structures due to device setup or experimental design. In this paper, we consider sonar echo data collected from multiple terrain substrates with a dual-channel sonar head. Our goals are to identify the differential sonar responses to terrains and study the effectiveness of this dual-channel design in discriminating targets. We describe a unified analytical framework that achieves these goals rigorously, simultaneously, and automatically. The analysis was done by treating the echo envelope signals as functional responses and the terrain/channel information as covariates in a functional regression setting. We adopt functional mixed models that facilitate the estimation of terrain and channel effects while capturing the complex hierarchical structure in data. This unified analytical framework incorporates both Gaussian models and robust models. We fit the models using a full Bayesian approach, which enables us to perform multiple inferential tasks under the same modeling framework, including selecting models, estimating the effects of interest, identifying significant local regions, discriminating terrain types, and describing the discriminatory power of local regions. Our analysis of the sonar-terrain data identifies time regions that reflect differential sonar responses to terrains. The discriminant analysis suggests that a multi- or dual-channel design achieves target identification performance comparable with or better than a single-channel design. PMID:29749977

Hydrogeological characterisation and prospect of basement Aquifers of Ibarapa region, southwestern Nigeria

NASA Astrophysics Data System (ADS)

Akanbi, Olanrewaju Akinfemiwa

2018-06-01

The present study involved the use of 82 geo-electric soundings, and the measurement of well inventory and conduct of yield tests in 19 wells across the various bedrock terrains of Ibarapa region of southwestern Nigeria. The aim is to proffer solution to the unsustainable yield of the available boreholes in order to effectively exploit the existing groundwater resource in the area. From the geological reports, the area is underlain by four principal crystalline rocks that include porphyritic granite, gneisses, amphibolite and migmatite. The geo-electric studies revealed that the degree and extent of development of the weathered-fractured component varied, leading to diversity in groundwater yield and in aquifer vulnerability to contamination. The thickness of the weathered layer is greater than 18 m in areas underlain by amphibolite and gneisses and less than 13 m within migmatite and porphyritic granite terrains. High groundwater yield greater than 70 m3/day was recorded in wells within the zones of rock contacts and in areas with large concentration of bedrock fractures and elevated locations across the various bedrock terrains. Aquifer vulnerability is low in amphibolite, high in granitic terrains, low to moderate in gneisses and high to moderate in migmatite. Also, wells' depths and terrain elevation have a moderate to strong indirect relationship with groundwater yield in most bedrock terrains, except in high topographic areas underlain by porphyritic granite. Therefore, there is need for modification of well depth in accordance with the terrain elevation and hydrogeological complexity of the weathered-fractured components of the variuos bedrock terrains, so as to ensure a sustainable groundwater yield.

Immune systems are not just for making you feel better: they are for controlling autonomous robots

NASA Astrophysics Data System (ADS)

Rosenblum, Mark

2005-05-01

The typical algorithm for robot autonomous navigation in off-road complex environments involves building a 3D map of the robot's surrounding environment using a 3D sensing modality such as stereo vision or active laser scanning, and generating an instantaneous plan to navigate around hazards. Although there has been steady progress using these methods, these systems suffer from several limitations that cannot be overcome with 3D sensing and planning alone. Geometric sensing alone has no ability to distinguish between compressible and non-compressible materials. As a result, these systems have difficulty in heavily vegetated environments and require sensitivity adjustments across different terrain types. On the planning side, these systems have no ability to learn from their mistakes and avoid problematic environmental situations on subsequent encounters. We have implemented an adaptive terrain classification system based on the Artificial Immune System (AIS) computational model, which is loosely based on the biological immune system, that combines various forms of imaging sensor inputs to produce a "feature labeled" image of the scene categorizing areas as benign or detrimental for autonomous robot navigation. Because of the qualities of the AIS computation model, the resulting system will be able to learn and adapt on its own through interaction with the environment by modifying its interpretation of the sensor data. The feature labeled results from the AIS analysis are inserted into a map and can then be used by a planner to generate a safe route to a goal point. The coupling of diverse visual cues with the malleable AIS computational model will lead to autonomous robotic ground vehicles that require less human intervention for deployment in novel environments and more robust operation as a result of the system's ability to improve its performance through interaction with the environment.

Airborne measurements of turbulent trace gas fluxes and analysis of eddy structure in the convective boundary layer over complex terrain

NASA Astrophysics Data System (ADS)

Hasel, M.; Kottmeier, Ch.; Corsmeier, U.; Wieser, A.

2005-03-01

Using the new high-frequency measurement equipment of the research aircraft DO 128, which is described in detail, turbulent vertical fluxes of ozone and nitric oxide have been calculated from data sampled during the ESCOMPTE program in the south of France. Based on airborne turbulence measurements, radiosonde data and surface energy balance measurements, the convective boundary layer (CBL) is examined under two different aspects. The analysis covers boundary-layer convection with respect to (i) the control of CBL depth by surface heating and synoptic scale influences, and (ii) the structure of convective plumes and their vertical transport of ozone and nitric oxides. The orographic structure of the terrain causes significant differences between planetary boundary layer (PBL) heights, which are found to exceed those of terrain height variations on average. A comparison of boundary-layer flux profiles as well as mean quantities over flat and complex terrain and also under different pollution situations and weather conditions shows relationships between vertical gradients and corresponding turbulent fluxes. Generally, NO x transports are directed upward independent of the terrain, since primary emission sources are located near the ground. For ozone, negative fluxes are common in the lower CBL in accordance with the deposition of O 3 at the surface. The detailed structure of thermals, which largely carry out vertical transports in the boundary layer, are examined with a conditional sampling technique. Updrafts mostly contain warm, moist and NO x loaded air, while the ozone transport by thermals alternates with the background ozone gradient. Evidence for handover processes of trace gases to the free atmosphere can be found in the case of existing gradients across the boundary-layer top. An analysis of the size of eddies suggests the possibility of some influence of the heterogeneous terrain in mountainous area on the length scales of eddies.

Topoclimate effects on growing season length and montane conifer growth in complex terrain

NASA Astrophysics Data System (ADS)

Barnard, D. M.; Barnard, H. R.; Molotch, N. P.

2017-05-01

Spatial variability in the topoclimate-driven linkage between forest phenology and tree growth in complex terrain is poorly understood, limiting our understanding of how ecosystems function as a whole. To characterize the influence of topoclimate on phenology and growth, we determined the start, end, and length of the growing season (GSstart, GSend, and GSL, respectively) using the correlation between transpiration and evaporative demand, measured with sapflow. We then compared these metrics with stem relative basal area increment (relative BAI) at seven sites among elevation and aspects in a Colorado montane forest. As elevation increased, we found shorter GSL (-50 d km-1) due to later GSstart (40 d km-1) and earlier GSend (-10 d km-1). North-facing sites had a 21 d shorter GSL than south-facing sites at similar elevations (i.e. equal to 200 m elevation difference on a given aspect). Growing season length was positively correlated with relative BAI, explaining 83% of the variance. This study shows that topography exerts strong environmental controls on GSL and thus forest growth. Given the climate-related dependencies of these controls, the results presented here have important implications for ecosystem responses to changes in climate and highlight the need for improved phenology representation in complex terrain.

A simple and complete model for wind turbine wakes over complex terrain

NASA Astrophysics Data System (ADS)

Rommelfanger, Nick; Rajborirug, Mai; Luzzatto-Fegiz, Paolo

2017-11-01

Simple models for turbine wakes have been used extensively in the wind energy community, both as independent tools, as well as to complement more refined and computationally-intensive techniques. These models typically prescribe empirical relations for how the wake radius grows with downstream distance x and obtain the wake velocity at each x through the application of either mass conservation, or of both mass and momentum conservation (e.g. Katić et al. 1986; Frandsen et al. 2006; Bastankhah & Porté-Agel 2014). Since these models assume a global behavior of the wake (for example, linear spreading with x) they cannot respond to local changes in background flow, as may occur over complex terrain. Instead of assuming a global wake shape, we develop a model by relying on a local assumption for the growth of the turbulent interface. To this end, we introduce to wind turbine wakes the use of the entrainment hypothesis, which has been used extensively in other areas of geophysical fluid dynamics. We obtain two coupled ordinary differential equations for mass and momentum conservation, which can be readily solved with a prescribed background pressure gradient. Our model is in good agreement with published data for the development of wakes over complex terrain.

The New WindForS Wind Energy Test Site in Southern Germany

NASA Astrophysics Data System (ADS)

Clifton, A. J.

2017-12-01

Wind turbines are increasingly being installed in complex terrain where patchy landcover, forestry, steep slopes, and complex regional and local atmospheric conditions lead to major challenges for traditional numerical weather prediction methods. In this presentation, the new WindForS complex terrain test site will be introduced. WindForS is a southern Germany-based research consortium of more than 20 groups at higher education and research institutes, with strong links to regional government and industry. The new test site will be located in the hilly, forested terrain of the Swabian Alps between Stuttgart and Germany, and will consist of two wind turbines with four meteorological towers. The test site will be used for accompanying ecological research and will also have mobile eddy covariance measurement stations as well as bird and bat monitoring systems. Seismic and noise monitoring systems are also planned. The large number of auxiliary measurements at this facility are intended to allow the complete atmosphere-wind turbine-environment-people system to be characterized. This presentation will show some of the numerical weather prediction work and measurements done at the site so far, and inform the audience about WindForS' plans for the future. A major focus of the presentation will be on opportunities for collaboration through field campaigns or model validation.

Discovery of a Plains Caldera Complex and Extinct Lava Lake in Arabia Terra, Mars: Implications for the Discovery of Additional Highland Volcanic Source Regions

NASA Technical Reports Server (NTRS)

Bleacher, Jacob; Michalski, Joseph

2012-01-01

Several irregularly shaped topographic depressions occur near the dichotomy boundary in northern Arabia Terra, Mars. The geomorphology of these features suggests that they formed by collapse, opposed to meteor impact. At least one depression (approx.55 by 85 km) displays geologic features indicating a complex, multi-stage collapse history. Features within and around the collapse structure indicate volcanic processes. The complex occurs within Hesperian ridged plains of likely volcanic origin and displays no crater rim or evidence for ejecta. Instead the depression consists of a series of circumferential graben and down-dropped blocks which also display upper surfaces similar to ridged plain lavas. Large blocks within the depression are tilted towards the crater center, and display graben that appear to have originally been linked with circumferential graben outside of the complex related to earlier collapse events. A nearly 700 m high mound exists along a graben within the complex that might be a vent. The deepest depression displays two sets of nearly continuous terraces, which we interpret as high-stands of a drained lava lake. These features appear similar to the black ledge described during the Kilauea Iki eruption in 1959. A lacustrine origin for the terraces seems unlikely because of the paucity of channels found in or around the depression that could be linked to aqueous surface processes. In addition, there is no obvious evidence for lacustrine sediments within the basin. Together with the presence of significant faulting that is indicative of collapse we conclude that this crater complex represents a large caldera formed in the Late Noachian to Early Hesperian. Other linear and irregular depressions in the region also might be linked to ancient volcanism. If that hypothesis is correct, it suggests that northern Arabia Terra could contain a large, previously unrecognized highland igneous province. Evacuation of magma via explosive and effusive activity produced localized collapse, might have contributed to nearby ridged plains, and pyroclastic materials erupted from these vents might have supplied sediments in fretted terrain and other deposits. The recognition of volcanoes within Arabia Terra expands the known extent of Noachian-Hesperian volcanism to cover much of the preserved martian highland crust.

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 the evolution of the deepest part of Hellas.

Near-infrared detection of potential evidence for microscopic organisms on Europa

NASA Technical Reports Server (NTRS)

Dalton, J. Brad; Mogul, Rakesh; Kagawa, Hiromi K.; Chan, Suzanne L.; Jamieson, Corey S.

2003-01-01

The possibility of an ocean within the icy shell of Jupiter's moon Europa has established that world as a primary candidate in the search for extraterrestrial life within our Solar System. This paper evaluates the potential to detect evidence for microbial life by comparing laboratory studies of terrestrial microorganisms with measurements from the Galileo Near Infrared Imaging Spectrometer (NIMS). If the interior of Europa at one time harbored life, some evidence may remain in the surface materials. Examination of laboratory spectra of terrestrial extremophiles measured at cryogenic temperatures reveals distorted, asymmetric nearinfrared absorption features due to water of hydration. The band centers, widths, and shapes of these features closely match those observed in the Europa spectra. These features are strongest in reddish-brown, disrupted terrains such as linea and chaos regions. Narrow spectral features due to amide bonds in the microbe proteins provide a means of constraining the abundances of such materials using the NIMS data. The NIMS data of disrupted terrains exhibit distorted, asymmetric near-infrared absorption features consistent with the presence of water ice, sulfuric acid octahydrate, hydrated salts, and possibly as much as 0.2 mg cm(-3) of carbonaceous material that could be of biological origin. However, inherent noise in the observations and limitations of spectral sampling must be taken into account when discussing these findings.

A rapid approach for automated comparison of independently derived stream networks

USGS Publications Warehouse

Stanislawski, Larry V.; Buttenfield, Barbara P.; Doumbouya, Ariel T.

2015-01-01

This paper presents an improved coefficient of line correspondence (CLC) metric for automatically assessing the similarity of two different sets of linear features. Elevation-derived channels at 1:24,000 scale (24K) are generated from a weighted flow-accumulation model and compared to 24K National Hydrography Dataset (NHD) flowlines. The CLC process conflates two vector datasets through a raster line-density differencing approach that is faster and more reliable than earlier methods. Methods are tested on 30 subbasins distributed across different terrain and climate conditions of the conterminous United States. CLC values for the 30 subbasins indicate 44–83% of the features match between the two datasets, with the majority of the mismatching features comprised of first-order features. Relatively lower CLC values result from subbasins with less than about 1.5 degrees of slope. The primary difference between the two datasets may be explained by different data capture criteria. First-order, headwater tributaries derived from the flow-accumulation model are captured more comprehensively through drainage area and terrain conditions, whereas capture of headwater features in the NHD is cartographically constrained by tributary length. The addition of missing headwaters to the NHD, as guided by the elevation-derived channels, can substantially improve the scientific value of the NHD.

Automated thematic mapping and change detection of ERTS-A images. [farmlands, cities, and mountain identification in Utah, Washington, Arizona, and California

NASA Technical Reports Server (NTRS)

Gramenopoulos, N. (Principal Investigator)

1974-01-01

The author has identified the following significant results. A diffraction pattern analysis of MSS images led to the development of spatial signatures for farm land, urban areas and mountains. Four spatial features are employed to describe the spatial characteristics of image cells in the digital data. Three spectral features are combined with the spatial features to form a seven dimensional vector describing each cell. Then, the classification of the feature vectors is accomplished by using the maximum likelihood criterion. It was determined that the recognition accuracy with the maximum likelihood criterion depends on the statistics of the feature vectors. It was also determined that for a given geographic area the statistics of the classes remain invariable for a period of a month, but vary substantially between seasons. Three ERTS-1 images from the Phoenix, Arizona area were processed, and recognition rates between 85% and 100% were obtained for the terrain classes of desert, farms, mountains, and urban areas. To eliminate the need for training data, a new clustering algorithm has been developed. Seven ERTS-1 images from four test sites have been processed through the clustering algorithm, and high recognition rates have been achieved for all terrain classes.

Near-infrared detection of potential evidence for microscopic organisms on Europa.

PubMed

Dalton, J Brad; Mogul, Rakesh; Kagawa, Hiromi K; Chan, Suzanne L; Jamieson, Corey S

2003-01-01

The possibility of an ocean within the icy shell of Jupiter's moon Europa has established that world as a primary candidate in the search for extraterrestrial life within our Solar System. This paper evaluates the potential to detect evidence for microbial life by comparing laboratory studies of terrestrial microorganisms with measurements from the Galileo Near Infrared Imaging Spectrometer (NIMS). If the interior of Europa at one time harbored life, some evidence may remain in the surface materials. Examination of laboratory spectra of terrestrial extremophiles measured at cryogenic temperatures reveals distorted, asymmetric nearinfrared absorption features due to water of hydration. The band centers, widths, and shapes of these features closely match those observed in the Europa spectra. These features are strongest in reddish-brown, disrupted terrains such as linea and chaos regions. Narrow spectral features due to amide bonds in the microbe proteins provide a means of constraining the abundances of such materials using the NIMS data. The NIMS data of disrupted terrains exhibit distorted, asymmetric near-infrared absorption features consistent with the presence of water ice, sulfuric acid octahydrate, hydrated salts, and possibly as much as 0.2 mg cm(-3) of carbonaceous material that could be of biological origin. However, inherent noise in the observations and limitations of spectral sampling must be taken into account when discussing these findings.

Dawn HAMO Image 70

NASA Image and Video Library

2015-12-04

This view from NASA's Dawn spacecraft shows different types of terrain located side by side on Ceres: a smooth terrain at right with numerous small impact craters, and a less-cratered, hummocky terrain at left. A huge crater chain crosses the scene diagonally from upper left to lower right. The smooth terrain, which is in the western part of Yalode impact basin, is interrupted by a set of roughly parallel furrows and ridges at upper right. These linear features are perpendicular to another set of smaller, fainter linear markings, which appear just below them. An impact into the hummocky terrain formed a crater, seen at left, 14 miles (22 kilometers) in diameter with a central peak. A great deal of material has slumped down the walls of the crater -- a phenomenon called mass wasting. The crater's impact ejecta forms a smooth blanket around its rim, which takes on a streaky texture leading away from the crater toward lower right. The image was taken during in Dawn's High Altitude Mapping Orbit (HAMO) phase from an altitude of 911 miles (1,466 kilometers) on Oct. 6, 2015. Image resolution is 394 feet (120 meters) per pixel. The image is centered at 37 degrees south latitude, 279 degrees east longitude. http://photojournal.jpl.nasa.gov/catalog/PIA20133

Active formation of `chaos terrain' over shallow subsurface water on Europa

NASA Astrophysics Data System (ADS)

Schmidt, B. E.; Blankenship, D. D.; Patterson, G. W.; Schenk, P. M.

2011-11-01

Europa, the innermost icy satellite of Jupiter, has a tortured young surface and sustains a liquid water ocean below an ice shell of highly debated thickness. Quasi-circular areas of ice disruption called chaos terrains are unique to Europa, and both their formation and the ice-shell thickness depend on Europa's thermal state. No model so far has been able to explain why features such as Conamara Chaos stand above surrounding terrain and contain matrix domes. Melt-through of a thin (few-kilometre) shell is thermodynamically improbable and cannot raise the ice. The buoyancy of material rising as either plumes of warm, pure ice called diapirs or convective cells in a thick (>10 kilometres) shell is insufficient to produce the observed chaos heights, and no single plume can create matrix domes. Here we report an analysis of archival data from Europa, guided by processes observed within Earth's subglacial volcanoes and ice shelves. The data suggest that chaos terrains form above liquid water lenses perched within the ice shell as shallow as 3kilometres. Our results suggest that ice-water interactions and freeze-out give rise to the diverse morphologies and topography of chaos terrains. The sunken topography of Thera Macula indicates that Europa is actively resurfacing over a lens comparable in volume to the Great Lakes in North America.

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

NASA Astrophysics Data System (ADS)

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

A new version of an advanced mesoscale dispersion modeling system for simulating passive air pollutant dispersion in the real atmospheric planetary boundary layer (PBL), is presented. The system comprises a diagnostic mass-consistent meteorological model and a Lagrangian particle dispersion model (LADISMO). The former version of LADISMO, developed according to Zannetti (Air pollution modelling, 1990), was based on the Monte Carlo technique and included calculation of higher-order moments of vertical random forcing for convective conditions. Its ability to simulate complex flow dispersion has been stated in a previous paper (Hernández et al. 1995, Atmospheric Environment, 29A, 1331-1341). The new version follows Thomson's scheme (1984, Q. Jl Roy. Met. Soc.110, 1107-1120). It is also based on Langevin equation and follows the ideas given by Brusasca et al. (1992, Atmospheric Environment26A, 707-723) and Anfossi et al. (1992, Nuovo Cemento 15c, 139-158). The model is used to simulate the dispersion and predict the ground level concentration (g.l.c.) of a tracer (SF 6) released from both an elevated source ( case a) and a ground level source ( case b) in a highly complex mountainous terrain during neutral and synoptically dominated conditions ( case a) and light and apparently stable conditions ( case b). The last case is considered as being a specially difficult task to simulate. In fact, few works have reported situations with valley drainage flows in complex terrains and real stable atmospheric conditions with weak winds. The model assumes that nearly calm situations associated to strong stability and air stagnation, make the lowest layers of PBL poorly diffusive (Brusasca et al., 1992, Atmospheric Environment26A, 707-723). Model results are verified against experimental data from Guardo-90 tracer experiments, an intensive field campaign conducted in the Carrion river valley (Northern Spain) to study atmospheric diffusion within a steep walled valley in mountainous terrain (Ibarra, 1992, Energia, No. 1, 74-85).

Persistent Monitoring of Urban Infrasound Phenomenology-Report 2: Investigation of Structural Infrasound Signals in an Urban Environment

DTIC Science & Technology

2016-11-01

space houses, etc.), and the unique weather environments that occur in the Urban Heat Island. A detailed urban terrain model was developed in a...affected by urban infrastructure (large buildings, roadways, densely space houses, etc.). A detailed urban terrain model was developed ERDC TR-15-5...different points in the model provided insight to complex propagation paths characteristic of urban environments. ERDC TR-15-5; Report 2 20 4

Atmospheric stability effects on wind fields and scalar mixing within and just above a subalpine forest in sloping terrain

USGS Publications Warehouse

Burns, Sean P.; Sun, Jielun; Lenschow, D.H.; Oncley, S.P.; Stephens, B.B.; Yi, C.; Anderson, D.E.; Hu, Jiawen; Monson, Russell K.

2011-01-01

Air temperature Ta, specific humidity q, CO2 mole fraction ??c, and three-dimensional winds were measured in mountainous terrain from five tall towers within a 1 km region encompassing a wide range of canopy densities. The measurements were sorted by a bulk Richardson number Rib. For stable conditions, we found vertical scalar differences developed over a "transition" region between 0.05 < Rib < 0.5. For strongly stable conditions (Rib > 1), the vertical scalar differences reached a maximum and remained fairly constant with increasing stability. The relationships q and ??c have with Rib are explained by considering their sources and sinks. For winds, the strong momentum absorption in the upper canopy allows the canopy sublayer to be influenced by pressure gradient forces and terrain effects that lead to complex subcanopy flow patterns. At the dense-canopy sites, soil respiration coupled with wind-sheltering resulted in CO2 near the ground being 5-7 ??mol mol-1 larger than aloft, even with strong above-canopy winds (near-neutral conditions). We found Rib-binning to be a useful tool for evaluating vertical scalar mixing; however, additional information (e.g., pressure gradients, detailed vegetation/topography, etc.) is needed to fully explain the subcanopy wind patterns. Implications of our results for CO2 advection over heterogenous, complex terrain are discussed. ?? 2010 Springer Science+Business Media B.V.

Young Lunar Volcanic Features: Thermophysical Properties and Formation

NASA Astrophysics Data System (ADS)

Elder, C. M.; Hayne, P. O.; Donaldson Hanna, K. L.; Bandfield, J.; Ghent, R. R.; Williams, J. P.; Paige, D. A.

2016-12-01

Irregular Mare Patches (IMPs) are small features (100 - 5000 m) on the lunar nearside characterized by uneven terrain interspersed with topographically higher smooth terrain. Crater counting suggests that they are less than 100 Myr old [1, 2]. Several formation hypotheses have been proposed for IMPs, including: caldera collapse [3], explosive outgassing [2], lava flow inflation [4], pyroclastic eruption [5], and regolith drainage [6]. In this study, we use thermal infrared data from the Lunar Reconnaissance Orbiter (LRO) Diviner radiometer to investigate the thermophysical properties of the IMPs. We find that their average rock abundance is approximately a factor of two higher than the surrounding terrain. Comparison of Diviner data with thermal models rules out extensive competent rocks within 5-10 cm of the surface at the IMPs. We also derive the regolith thermal inertia [7] of the four largest IMPs. Sosigenes, Maskelyne, and Cauchy-5 have thermal inertias slightly higher than their surrounding terrain, likely due to the presence of small rocks surrounding nearby craters. Ina has an average thermal inertia lower than the surrounding terrain, and the only resolved smooth mound in Ina has an even lower thermal inertia which implies material that is less consolidated than typical regolith and/or contains fewer small rocks. Formation by lava flows or regolith drainage is not expected to result in material with a lower thermal inertia than pre-existing regolith, so in the case of at least Ina, some other process such as explosive outgassing or pyroclastic eruptions must have occurred. [1] Braden, S. et al. (2014) Nature Geo 7, 787-791. [2] Schultz, P. H. et al. (2006) Nature 444, 184-186. [3] El-Baz, F. (1973) Apollo 17: Preliminary Science Report 330, 30-13. [4] Garry, W. B. et al. (2012) JGR 117, E00H31. [5] Carter, L. B. et al. (2013) LPSC 44, 2146. [6] Qiao, L. et al. (2002) LPSC 47, 2002. [7] Vasavada, A. R. et al. (2012) JGR 117, E00H18.

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 these spatially distributed measurements are time consuming. Looking forward, we have begun using unmanned aerial vehicles outfitted with thermal and multi-spectral cameras to quantify patterns of water flux, NDVI, needle browning due to moisture stress, and overall phenology in the CZ.

Crustal Fractures of Ophir Planum

NASA Technical Reports Server (NTRS)

2002-01-01

(Released 29 April 2002) The Science This THEMIS image covers a tract of plateau territory called Ophir Planum. The most obvious features in this scene are the fractures (ranging from 1 to 5 km wide) running from the upper left to lower right. Localized rifting and deep-seated tension fracturing of the crust probably formed these cracks. The wall rock displayed in the upper part of the cliffs appears to be layered. The southwest-facing wall of the largest and uppermost fracture has classic spur and gully topography. This type of topography is created by differing amounts of erosion. Also seen in this image are some scattered impact craters and some dark wind streaks in the lower right. The Ophir Planum plateau separates two separate smaller canyon systems, not visible in this image, (Candor Chasma to the north and Melas Chasma to the south) in the Valles Marineris canyon complex. The whole Valles Marineris canyon system extends some 4,000 km across the equatorial realms of Mars. For comparison, this would stretch from New York City to San Francisco. The Story Plateaus and spurs might make you think of cowboys on the open plain. 'Spurs' in this context, however, are simply ridges that can be seen on the side of the southwest-facing wall of the large fracture that splits the terrain. Gullies stretch down this slope as well. Both of these features are caused by erosion, which is a mild force of change compared to whatever tension cracked the crust and ripped apart the land. The wall rock displayed in the upper part of the cliffs appears to be layered, suggesting that different kinds of rocks and minerals can be found in each banded zone. The Ophir Planum plateau separates two separate canyon systems in the Valles Marineris complex, the largest canyon in the solar system. If Valles Marineris were on Earth, it would stretch from New York City all the way to San Francisco. That will give you some idea of the geological forces that have acted upon the planet over time. Look for scattered impact craters and some dark wind streaks in the deep dark terrain (lower right) as well.

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. However, most of the hazardous materials being released into the environment from nuclear power plants are not neutral pollutants, so the particle and multi-segment puff models can be regarded as the most suitable models to incorporate into the output of the diagnostic wind field model in a modern emergency preparedness and response system. The proposed SDSS illustrates the state-of-the-art system design based on the situation of complex terrain in South Taiwan. This system design of SDSS with 3-dimensional animation capability using a tailored source term model in connection with ArcView® Geographical Information System map layers and remote sensing images is useful for meeting the design goal of nuclear power plants located in complex terrain.

The nature of terrains of different types on the surface of Venus and selection of potential landing sites for a descent probe of the Venera-D Mission

NASA Astrophysics Data System (ADS)

Ivanov, M. A.; Zasova, L. V.; Gerasimov, M. V.; Korablev, O. I.; Marov, M. Ya.; Zelenyi, L. M.; Ignat'ev, N. I.; Tuchin, A. G.

2017-01-01

We discuss a change in the resurfacing regimes of Venus and probable ways of forming the terrain types that make up the surface of the planet. The interpretation of the nature of the terrain types and their morphologic features allows us to characterize their scientific priority and the risk of landing on their surface to be estimated. From the scientific point of view, two terrain types are of special interest and represent easily achievable targets: the lower unit of regional plains and the smooth plains associated with impact craters. Regional plains are probably a melting from the upper fertile mantle. The material of smooth plains of impact origin is a well-mixed and representative sample of the Venusian crust. The lower unit of regional plains is the most widespread one on the surface of Venus, and it occurs within the boundaries of all of the precalculated approach trajectories of the lander. Smooth plains of impact origin are crossed by the approach trajectories precalculated for 2018 and 2026.

A Height Estimation Approach for Terrain Following Flights from Monocular Vision

PubMed Central

Campos, Igor S. G.; Nascimento, Erickson R.; Freitas, Gustavo M.; Chaimowicz, Luiz

2016-01-01

In this paper, we present a monocular vision-based height estimation algorithm for terrain following flights. The impressive growth of Unmanned Aerial Vehicle (UAV) usage, notably in mapping applications, will soon require the creation of new technologies to enable these systems to better perceive their surroundings. Specifically, we chose to tackle the terrain following problem, as it is still unresolved for consumer available systems. Virtually every mapping aircraft carries a camera; therefore, we chose to exploit this in order to use presently available hardware to extract the height information toward performing terrain following flights. The proposed methodology consists of using optical flow to track features from videos obtained by the UAV, as well as its motion information to estimate the flying height. To determine if the height estimation is reliable, we trained a decision tree that takes the optical flow information as input and classifies whether the output is trustworthy or not. The classifier achieved accuracies of 80% for positives and 90% for negatives, while the height estimation algorithm presented good accuracy. PMID:27929424

Cooperative Exploration of Rough Martian Terrains with the "Scorpion" Legged Robot as an Adjunct to a Rover.

NASA Technical Reports Server (NTRS)

Colombano, Silvano P.; Kirchner, Frank; Spenneberg, Dirk; Starman, Jared; Hanratty, James; Kovsmeyer, David (Technical Monitor)

2003-01-01

NASA needs autonomous robotic exploration of difficult (rough and/or steep) scientifically interesting Martian terrains. Concepts involving distributed autonomy for cooperative robotic exploration are key to enabling new scientific objectives in robotic missions. We propose to utilize a legged robot as an adjunct scout to a rover for access to difficult - scientifically interesting - terrains (rocky areas, slopes, cliffs). Our final mission scenario involves the Ames rover platform "K9" and Scorpion acting together to explore a steep cliff, with the Scorpion robot rappelling down using the K9 as an anchor as well as mission planner and executive. Cooperation concepts, including wheeled rappelling robots have been proposed before. Now we propose to test the combined advantages of a wheeled vehicle with a legged scout as well as the advantages of merging of high level planning and execution with biologically inspired, behavior based robotics. We propose to use the 8-legged, multifunctional autonomous robot platform Scorpion that is currently capable of: Walking on different terrains (rocks, sand, grass, ...). Perceiving its environment and modifying its behavioral pattern accordingly. These capabilities would be extended to enable the Scorpion to: communicate and cooperate with a partner robot; climb over rocks, rubble piles, and objects with structural features. This will be done in the context of exploration of rough terrains in the neighborhood of the rover, but inaccessible to it, culminating in the added capability of rappelling down a steep cliff for both vertical and horizontal terrain observation.

Integrating remote sensing and terrain data in forest fire modeling

NASA Astrophysics Data System (ADS)

Medler, Michael Johns

Forest fire policies are changing. Managers now face conflicting imperatives to re-establish pre-suppression fire regimes, while simultaneously preventing resource destruction. They must, therefore, understand the spatial patterns of fires. Geographers can facilitate this understanding by developing new techniques for mapping fire behavior. This dissertation develops such techniques for mapping recent fires and using these maps to calibrate models of potential fire hazards. In so doing, it features techniques that strive to address the inherent complexity of modeling the combinations of variables found in most ecological systems. Image processing techniques were used to stratify the elements of terrain, slope, elevation, and aspect. These stratification images were used to assure sample placement considered the role of terrain in fire behavior. Examination of multiple stratification images indicated samples were placed representatively across a controlled range of scales. The incorporation of terrain data also improved preliminary fire hazard classification accuracy by 40%, compared with remotely sensed data alone. A Kauth-Thomas transformation (KT) of pre-fire and post-fire Thematic Mapper (TM) remotely sensed data produced brightness, greenness, and wetness images. Image subtraction indicated fire induced change in brightness, greenness, and wetness. Field data guided a fuzzy classification of these change images. Because fuzzy classification can characterize a continuum of a phenomena where discrete classification may produce artificial borders, fuzzy classification was found to offer a range of fire severity information unavailable with discrete classification. These mapped fire patterns were used to calibrate a model of fire hazards for the entire mountain range. Pre-fire TM, and a digital elevation model produced a set of co-registered images. Training statistics were developed from 30 polygons associated with the previously mapped fire severity. Fuzzy classifications of potential burn patterns were produced from these images. Observed field data values were displayed over the hazard imagery to indicate the effectiveness of the model. Areas that burned without suppression during maximum fire severity are predicted best. Areas with widely spaced trees and grassy understory appear to be misrepresented, perhaps as a consequence of inaccuracies in the initial fire mapping.

Assessment of Wind Resource in the Palk Strait using Different Methods

NASA Astrophysics Data System (ADS)

Gupta, T.; Khan, F.; Baidya Roy, S.; Miller, L.

2017-12-01

The Government of India has proposed a target of 60 GW in grid power from the wind by the year 2022. The Palk Strait is one of the potential offshore wind power generation sites in India. It is a 65-135 km wide and 135 km long channel lying between the south eastern tip of India and northern Sri Lanka. The complex terrain bounding the two sides of the strait leads to enhanced wind speed and reduced variability in the wind direction. Here, we compare 3 distinct methodologies for estimating the generation rates for a hypothetical offshore wind farm array located in the strait. The methodologies include: 1) traditional wind power density model that ignores the effect of turbine interactions on generation rates; 2) the PARK wake model; and 3) a high resolution weather model (WRF) with a wind turbine parameterization. Using the WRF model as our baseline, we find that the simple model overestimates generation by an order-of-magnitude, while the wake model underestimates generation rates by about 5%. The reason for these differences relates to the influence of wind turbines on the atmospheric flow, wherein, the WRF model is able to capture the effect of both the complex terrain and wind turbine atmospheric boundary layer interactions. Lastly, a model evaluation is conducted which shows that 10m wind speeds and directions from WRF are comparable with the satellite data. Hence, we conclude from the study that each of these methodologies may have merit, but should a wind farm is deployed in such a complex terrain, we expect the WRF method to give better estimates of wind resource assessment capturing the physical processes emerging due to the interactions between offshore wind farm and the surrounding terrain.

Linearized simulation of flow over wind farms and complex terrains.

PubMed

Segalini, Antonio

2017-04-13

The flow over complex terrains and wind farms is estimated here by numerically solving the linearized Navier-Stokes equations. The equations are linearized around the unperturbed incoming wind profile, here assumed logarithmic. The Boussinesq approximation is used to model the Reynolds stress with a prescribed turbulent eddy viscosity profile. Without requiring the boundary-layer approximation, two new linear equations are obtained for the vertical velocity and the wall-normal vorticity, with a reduction in the computational cost by a factor of 8 when compared with a primitive-variables formulation. The presence of terrain elevation is introduced as a vertical coordinate shift, while forestry or wind turbines are included as body forces, without any assumption about the wake structure for the turbines. The model is first validated against some available experiments and simulations, and then a simulation of a wind farm over a Gaussian hill is performed. The speed-up effect of the hill is clearly beneficial in terms of the available momentum upstream of the crest, while downstream of it the opposite can be said as the turbines face a decreased wind speed. Also, the presence of the hill introduces an additional spanwise velocity component that may also affect the turbines' operations. The linear superposition of the flow over the hill and the flow over the farm alone provided a first estimation of the wind speed along the farm, with discrepancies of the same order of magnitude for the spanwise velocity. Finally, the possibility of using a parabolic set of equations to obtain the turbulent kinetic energy after the linearized model is investigated with promising results.This article is part of the themed issue 'Wind energy in complex terrains'. © 2017 The Author(s).

Linearized simulation of flow over wind farms and complex terrains

NASA Astrophysics Data System (ADS)

Segalini, Antonio

2017-03-01

The flow over complex terrains and wind farms is estimated here by numerically solving the linearized Navier-Stokes equations. The equations are linearized around the unperturbed incoming wind profile, here assumed logarithmic. The Boussinesq approximation is used to model the Reynolds stress with a prescribed turbulent eddy viscosity profile. Without requiring the boundary-layer approximation, two new linear equations are obtained for the vertical velocity and the wall-normal vorticity, with a reduction in the computational cost by a factor of 8 when compared with a primitive-variables formulation. The presence of terrain elevation is introduced as a vertical coordinate shift, while forestry or wind turbines are included as body forces, without any assumption about the wake structure for the turbines. The model is first validated against some available experiments and simulations, and then a simulation of a wind farm over a Gaussian hill is performed. The speed-up effect of the hill is clearly beneficial in terms of the available momentum upstream of the crest, while downstream of it the opposite can be said as the turbines face a decreased wind speed. Also, the presence of the hill introduces an additional spanwise velocity component that may also affect the turbines' operations. The linear superposition of the flow over the hill and the flow over the farm alone provided a first estimation of the wind speed along the farm, with discrepancies of the same order of magnitude for the spanwise velocity. Finally, the possibility of using a parabolic set of equations to obtain the turbulent kinetic energy after the linearized model is investigated with promising results. This article is part of the themed issue 'Wind energy in complex terrains'.

GeoSciML and EarthResourceML Update, 2012

NASA Astrophysics Data System (ADS)

Richard, S. M.; Commissionthe Management; Application Inte, I.

2012-12-01

CGI Interoperability Working Group activities during 2012 include deployment of services using the GeoSciML-Portrayal schema, addition of new vocabularies to support properties added in version 3.0, improvements to server software for deploying services, introduction of EarthResourceML v.2 for mineral resources, and collaboration with the IUSS on a markup language for soils information. GeoSciML and EarthResourceML have been used as the basis for the INSPIRE Geology and Mineral Resources specifications respectively. GeoSciML-Portrayal is an OGC GML simple-feature application schema for presentation of geologic map unit, contact, and shear displacement structure (fault and ductile shear zone) descriptions in web map services. Use of standard vocabularies for geologic age and lithology enables map services using shared legends to achieve visual harmonization of maps provided by different services. New vocabularies have been added to the collection of CGI vocabularies provided to support interoperable GeoSciML services, and can be accessed through http://resource.geosciml.org. Concept URIs can be dereferenced to obtain SKOS rdf or html representations using the SISSVoc vocabulary service. New releases of the FOSS GeoServer application greatly improve support for complex XML feature schemas like GeoSciML, and the ArcGIS for INSPIRE extension implements similar complex feature support for ArcGIS Server. These improved server implementations greatly facilitate deploying GeoSciML services. EarthResourceML v2 adds features for information related to mining activities. SoilML provides an interchange format for soil material, soil profile, and terrain information. Work is underway to add GeoSciML to the portfolio of Open Geospatial Consortium (OGC) specifications.

(FRANCE) USING THE QUIC MODEL (QUICK URBAN AND INDUSTRIAL COMPLEX) TO STUDY AIR FLOW AND DISPERSION PATTERNS IN DESERTS

EPA Science Inventory

As part of its continuing development and evaluation, the QUIC model (Quick Urban & Industrial Complex) was used to study flow and dispersion in complex terrain for two cases. First, for a small area of lower Manhattan near the World Trade Center site, comparisons were made bet...

USING THE QUIC MODEL (QUICK URBAN AND INDUSTRIAL COMPLEX) TO STUDY AIR FLOW AND DISPERSION PATTERNS IN DESERTS

EPA Science Inventory

As part of its continuing development and evaluation, the QUIC model (Quick Urban & Industrial Complex) was used to study flow and dispersion in complex terrain for two cases. First, for a small area of lower Manhattan near the World Trade Center site, comparisons were made bet...

High-resolution dust modelling over complex terrains in West Asia

NASA Astrophysics Data System (ADS)

Basart, S.; Vendrell, L.; Baldasano, J. M.

2016-12-01

The present work demonstrates the impact of model resolution in dust propagation in a complex terrain region such as West Asia. For this purpose, two simulations using the NMMB/BSC-Dust model are performed and analysed, one with a high horizontal resolution (at 0.03° × 0.03°) and one with a lower horizontal resolution (at 0.33° × 0.33°). Both model experiments cover two intense dust storms that occurred on 17-20 March 2012 as a consequence of strong northwesterly Shamal winds that spanned over thousands of kilometres in West Asia. The comparison with ground-based (surface weather stations and sunphotometers) and satellite aerosol observations (Aqua/MODIS and MSG/SEVIRI) shows that despite differences in the magnitude of the simulated dust concentrations, the model is able to reproduce these two dust outbreaks. Differences between both simulations on the dust spread rise on regional dust transport areas in south-western Saudi Arabia, Yemen and Oman. The complex orography in south-western Saudi Arabia, Yemen and Oman (with peaks higher than 3000 m) has an impact on the transported dust concentration fields over mountain regions. Differences between both model configurations are mainly associated to the channelization of the dust flow through valleys and the differences in the modelled altitude of the mountains that alters the meteorology and blocks the dust fronts limiting the dust transport. These results demonstrate how the dust prediction in the vicinity of complex terrains improves using high-horizontal resolution simulations.

Multifractal Detrended Fluctuation Analysis of Regional Precipitation Sequences Based on the CEEMDAN-WPT

NASA Astrophysics Data System (ADS)

Liu, Dong; Cheng, Chen; Fu, Qiang; Liu, Chunlei; Li, Mo; Faiz, Muhammad Abrar; Li, Tianxiao; Khan, Muhammad Imran; Cui, Song

2018-03-01

In this paper, the complete ensemble empirical mode decomposition with the adaptive noise (CEEMDAN) algorithm is introduced into the complexity research of precipitation systems to improve the traditional complexity measure method specific to the mode mixing of the Empirical Mode Decomposition (EMD) and incomplete decomposition of the ensemble empirical mode decomposition (EEMD). We combined the CEEMDAN with the wavelet packet transform (WPT) and multifractal detrended fluctuation analysis (MF-DFA) to create the CEEMDAN-WPT-MFDFA, and used it to measure the complexity of the monthly precipitation sequence of 12 sub-regions in Harbin, Heilongjiang Province, China. The results show that there are significant differences in the monthly precipitation complexity of each sub-region in Harbin. The complexity of the northwest area of Harbin is the lowest and its predictability is the best. The complexity and predictability of the middle and Midwest areas of Harbin are about average. The complexity of the southeast area of Harbin is higher than that of the northwest, middle, and Midwest areas of Harbin and its predictability is worse. The complexity of Shuangcheng is the highest and its predictability is the worst of all the studied sub-regions. We used terrain and human activity as factors to analyze the causes of the complexity of the local precipitation. The results showed that the correlations between the precipitation complexity and terrain are obvious, and the correlations between the precipitation complexity and human influence factors vary. The distribution of the precipitation complexity in this area may be generated by the superposition effect of human activities and natural factors such as terrain, general atmospheric circulation, land and sea location, and ocean currents. To evaluate the stability of the algorithm, the CEEMDAN-WPT-MFDFA was compared with the equal probability coarse graining LZC algorithm, fuzzy entropy, and wavelet entropy. The results show that the CEEMDAN-WPT-MFDFA was more stable than 3 contrast methods under the influence of white noise and colored noise, which proves that the CEEMDAN-WPT-MFDFA has a strong robustness under the influence of noise.

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.

On the influence of meteorological input on photochemical modelling of a severe episode over a coastal area

NASA Astrophysics Data System (ADS)

Pirovano, G.; Coll, I.; Bedogni, M.; Alessandrini, S.; Costa, M. P.; Gabusi, V.; Lasry, F.; Menut, L.; Vautard, R.

The modelling reconstruction of the processes determining the transport and mixing of ozone and its precursors in complex terrain areas is a challenging task, particularly when local-scale circulations, such as sea breeze, take place. Within this frame, the ESCOMPTE European campaign took place in the vicinity of Marseille (south-east of France) in summer 2001. The main objectives of the field campaign were to document several photochemical episodes, as well as to constitute a detailed database for chemistry transport models intercomparison. CAMx model has been applied on the largest intense observation periods (IOP) (June 21-26, 2001) in order to evaluate the impacts of two state-of-the-art meteorological models, RAMS and MM5, on chemical model outputs. The meteorological models have been used as best as possible in analysis mode, thus allowing to identify the spread arising in pollutant concentrations as an indication of the intrinsic uncertainty associated to the meteorological input. Simulations have been deeply investigated and compared with a considerable subset of observations both at ground level and along vertical profiles. The analysis has shown that both models were able to reproduce the main circulation features of the IOP. The strongest discrepancies are confined to the Planetary Boundary Layer, consisting of a clear tendency to underestimate or overestimate wind speed over the whole domain. The photochemical simulations showed that variability in circulation intensity was crucial mainly for the representation of the ozone peaks and of the shape of ozone plumes at the ground that have been affected in the same way over the whole domain and all along the simulated period. As a consequence, such differences can be thought of as a possible indicator for the uncertainty related to the definition of meteorological fields in a complex terrain area.

Near-surface wind variability over the broader Adriatic region: insights from an ensemble of regional climate models

NASA Astrophysics Data System (ADS)

Belušić, Andreina; Prtenjak, Maja Telišman; Güttler, Ivan; Ban, Nikolina; Leutwyler, David; Schär, Christoph

2018-06-01

Over the past few decades the horizontal resolution of regional climate models (RCMs) has steadily increased, leading to a better representation of small-scale topographic features and more details in simulating dynamical aspects, especially in coastal regions and over complex terrain. Due to its complex terrain, the broader Adriatic region represents a major challenge to state-of-the-art RCMs in simulating local wind systems realistically. The objective of this study is to identify the added value in near-surface wind due to the refined grid spacing of RCMs. For this purpose, we use a multi-model ensemble composed of CORDEX regional climate simulations at 0.11° and 0.44° grid spacing, forced by the ERA-Interim reanalysis, a COSMO convection-parameterizing simulation at 0.11° and a COSMO convection-resolving simulation at 0.02° grid spacing. Surface station observations from this region and satellite QuikSCAT data over the Adriatic Sea have been compared against daily output obtained from the available simulations. Both day-to-day wind and its frequency distribution are examined. The results indicate that the 0.44° RCMs rarely outperform ERA-Interim reanalysis, while the performance of the high-resolution simulations surpasses that of ERA-Interim. We also disclose that refining the grid spacing to a few km is needed to properly capture the small-scale wind systems. Finally, we show that the simulations frequently yield the accurate angle of local wind regimes, such as for the Bora flow, but overestimate the associated wind magnitude. Finally, spectral analysis shows good agreement between measurements and simulations, indicating the correct temporal variability of the wind speed.

Integrating Geomorphic and Social Dynamics in the Analysis of Anthropogenic Landforms: Examining Landscape Evolution of Terrain Modified by Agricultural Terracing

NASA Astrophysics Data System (ADS)

Glaubius, J.; Maerker, M.

2016-12-01

Anthropogenic landforms, such as mines and agricultural terraces, are impacted by both geomorphic and social processes at varying intensities through time. In the case of agricultural terraces, decisions regarding terrace maintenance are intertwined with land use, such as when terraced fields are abandoned. Furthermore, terrace maintenance and land use decisions, either jointly or separately, may be in response to geomorphic processes, as well as geomorphic feedbacks. Previous studies of these complex geomorphic systems considered agricultural terraces as static features or analyzed only the geomorphic response to landowner decisions. Such research is appropriate for short-term or binary landscape scenarios (e.g. the impact of maintained vs. abandoned terraces), but the complexities inherent in these socio-natural systems requires an approach that includes both social and geomorphic processes. This project analyzes feedbacks and emergent properties in terraced systems by implementing a coupled landscape evolution model (LEM) and agent-based model (ABM) using the Landlab and Mesa modeling libraries. In the ABM portion of the model, agricultural terraces are conceptualized using a life-cycle stages schema and implemented using Markov Decision Processes to simulate the changing geomorphic impact of terracing based on human decisions. This paper examines the applicability of this approach by comparing results from a LEM-only model against the coupled LEM-ABM model for a terraced region. Model results are compared by quantify and spatial patterning of sediment transport. This approach fully captures long-term landscape evolution of terraced terrain that is otherwise lost when the life-cycle of terraces is not considered. The coupled LEM-ABM approach balances both environmental and social processes so that the socio-natural feedbacks in such anthropogenic systems can be disentangled.

Numerical Simulation of Nocturnal Drainage Flows in Idealized Valley-Tributary Systems.

NASA Astrophysics Data System (ADS)

O'Steen, Lance B.

2000-11-01

Numerical simulations of nocturnal drainage flow and transport in idealized valley-tributary systems are compared with the Atmospheric Science in Complex Terrain (ASCOT) meteorological field data and tracer studies from the Brush Creek valley of western Colorado. Much of the general valley-tributary flow behavior deduced from observations is qualitatively reproduced in the numerical results. The spatially complex, unsteady nature of the tributary flow found in the field data is also seen in the simulations. Oscillations in the simulated tributary flow are similar to some field observations. However, observed oscillations in the valley flow at the mouth of the tributary could not be reproduced in the numerical results. Thus, hypotheses of strongly coupled valley-tributary flow oscillations, based on field data, cannot be supported by these simulations. Along-valley mass flux calculations based on model results for the valley-tributary system indicate an increase of 5%-10% over a valley without a tributary. Enhanced valley mass fluxes were found from 8 km above the tributary to almost the valley mouth. However, the valley mass fluxes for topography with and without a tributary were nearly equal at the valley outflow. ASCOT field data suggested a tributary mass flow contribution of 5%-15% for a Brush Creek tributary of similar drainage area to the model tributary employed here. Numerical simulations of transport in the nocturnal valley-tributary flow strongly support ASCOT tracer studies in the Pack Canyon tributary of Brush Creek. These results suggest that the valley-tributary interaction can significantly increase plume dispersion under stable conditions. Overall, the simulation results presented here indicate that simple terrain geometries are able to capture many of the salient features of drainage flow in real valley-tributary systems.

Field Studies Delve Into the Intricacies of Mountain Weather

NASA Astrophysics Data System (ADS)

Fernando, Harindra J. S.; Pardyjak, Eric R.

2013-09-01

Mountain meteorology, in particular weather prediction in complex (rugged) terrain, is emerging as an important topic for science and society. Large urban settlements such as Los Angeles, Hong Kong, and Rio de Janeiro have grown within or in the shadow of complex terrain, and managing the air quality of such cities requires a good understanding of the air flow patterns that spill off of mountains. On a daily time scale, the interconnected engineered and natural systems that sustain urban metabolism and quality of life are affected by weather [Fernando, 2010]. Further, recent military engagements in remote mountainous areas have heightened the need for better weather predictions—alpine warfare is considered to be one of the most dangerous types of combat.

Mesoscale simulations of atmospheric flow and tracer transport in Phoenix, Arizona

NASA Astrophysics Data System (ADS)

Wang, Ge; Ostoja-Starzewski, Martin

2006-09-01

Large urban centres located within confining rugged or complex terrain can frequently experience episodes of high concentrations of lower atmospheric pollution. Metropolitan Phoenix, Arizona (United States), is a good example, as the general population is occasionally subjected to high levels of lower atmospheric ozone, carbon monoxide and suspended particulate matter. As a result of dramatic but continuous increase in population, the accompanying environmental stresses and the local atmospheric circulation that dominates the background flow, an accurate simulation of the mesoscale pollutant transport across Phoenix and similar urban areas is becoming increasingly important. This is particularly the case in an airshed, such as that of Phoenix, where the local atmospheric circulation is complicated by the complex terrain of the area.

Reminder of Ages Past

NASA Image and Video Library

2006-05-26

Rhea displays a prominent scar in this view from Cassini. A large and ancient impact basin can be seen at upper right. The giant feature occurs within a terrain that appears rugged and which likely is saturated with other smaller craters

Thermally anomalous features in the subsurface of Enceladus's south polar terrain

NASA Astrophysics Data System (ADS)

Le Gall, A.; Leyrat, C.; Janssen, M. A.; Choblet, G.; Tobie, G.; Bourgeois, O.; Lucas, A.; Sotin, C.; Howett, C.; Kirk, R.; Lorenz, R. D.; West, R. D.; Stolzenbach, A.; Massé, M.; Hayes, A. H.; Bonnefoy, L.; Veyssière, G.; Paganelli, F.

2017-03-01

Saturn's moon Enceladus is an active world. In 2005, the Cassini spacecraft witnessed for the first time water-rich jets venting from four anomalously warm fractures (called sulci) near its south pole1,2. Since then, several observations have provided evidence that the source of the material ejected from Enceladus is a large underground ocean, the depth of which is still debated3-6. Here, we report on the first and only opportunity that Cassini's RADAR instrument7,8 had to observe Enceladus's south polar terrain closely, targeting an area a few tens of kilometres north of the active sulci. Detailed analysis of the microwave radiometry observations highlights the ongoing activity of the moon. The instrument recorded the microwave thermal emission, revealing a warm subsurface region with prominent thermal anomalies that had not been identified before. These anomalies coincide with large fractures, similar or structurally related to the sulci. The observations imply the presence of a broadly distributed heat production and transport system below the south polar terrain with 'plate-like' features and suggest that a liquid reservoir could exist at a depth of only a few kilometres under the ice shell at the south pole. The detection of a possible dormant sulcus further suggests episodic geological activity.

Landslide Detection in the Carlyon Beach, WA Peninsula: Analysis Of High Resolution DEMs

NASA Astrophysics Data System (ADS)

Fayne, J.; Tran, C.; Mora, O. E.

2017-12-01

Landslides are geological events caused by slope instability and degradation, leading to the sliding of large masses of rock and soil down a mountain or hillside. These events are influenced by topography, geology, weather and human activity, and can cause extensive damage to the environment and infrastructure, such as the destruction of transportation networks, homes, and businesses. It is therefore imperative to detect early-warning signs of landslide hazards as a means of mitigation and disaster prevention. Traditional landslide surveillance consists of field mapping, but the process is expensive and time consuming. This study uses Light Detection and Ranging (LiDAR) derived Digital Elevation Models (DEMs) and k-means clustering and Gaussian Mixture Model (GMM) to analyze surface roughness and extract spatial features and patterns of landslides and landslide-prone areas. The methodology based on several feature extractors employs an unsupervised classifier on the Carlyon Beach Peninsula in the state of Washington to attempt to identify slide potential terrain. When compared with the independently compiled landslide inventory map, the proposed algorithm correctly classifies up to 87% of the terrain. These results suggest that the proposed methods and LiDAR-derived DEMs can provide important surface information and be used as efficient tools for digital terrain analysis to create accurate landslide maps.

Concretions in Exhumed Channels Near Hanksville Utah: Implications for Mars

NASA Technical Reports Server (NTRS)

Clarke, Jonathan; Stoker, Carol R.

2011-01-01

The landscape near Hanksville, Utah, contains a diversity of Mars analogue features. These included segmented and inverted anatasomosing palaeochannels exhumed from the Late Jurassic Brushy Basin Member of the Morrison Formation that hosts abundant small carbonate concretions. The exhumed and inverted channels closely resemble many seen on the surface of Mars in satellite imagery and which may be visited by surface missions in the near future. The channels contain a wealth of palaeo-environmental information, but intrinsically difficult terrain would make their study challenging on Mars. We show that an unexhumed channel feature can be detected geophysically, this may allow their study in more easily accessed terrain. The concretions morphologically and in their surface expression parallel the haematite blue berries that are strewn across the surface of Meridiani Planum on Mars. They are best developed in poorly cemented medium to coarse channel sandstones and appear to have formed early in the diagenetic history.

Aerial Explorers

NASA Technical Reports Server (NTRS)

Young, Larry A.; Pisanich, Greg; Ippolito, Corey

2005-01-01

This paper presents recent results from a mission architecture study of planetary aerial explorers. In this study, several mission scenarios were developed in simulation and evaluated on success in meeting mission goals. This aerial explorer mission architecture study is unique in comparison with previous Mars airplane research activities. The study examines how aerial vehicles can find and gain access to otherwise inaccessible terrain features of interest. The aerial explorer also engages in a high-level of (indirect) surface interaction, despite not typically being able to takeoff and land or to engage in multiple flights/sorties. To achieve this goal, a new mission paradigm is proposed: aerial explorers should be considered as an additional element in the overall Entry, Descent, Landing System (EDLS) process. Further, aerial vehicles should be considered primarily as carrier/utility platforms whose purpose is to deliver air-deployed sensors and robotic devices, or symbiotes, to those high-value terrain features of interest.

Robotics and local fusion

NASA Astrophysics Data System (ADS)

Emmerman, Philip J.

2005-05-01

Teams of robots or mixed teams of warfighters and robots on reconnaissance and other missions can benefit greatly from a local fusion station. A local fusion station is defined here as a small mobile processor with interfaces to enable the ingestion of multiple heterogeneous sensor data and information streams, including blue force tracking data. These data streams are fused and integrated with contextual information (terrain features, weather, maps, dynamic background features, etc.), and displayed or processed to provide real time situational awareness to the robot controller or to the robots themselves. These blue and red force fusion applications remove redundancies, lessen ambiguities, correlate, aggregate, and integrate sensor information with context such as high resolution terrain. Applications such as safety, team behavior, asset control, training, pattern analysis, etc. can be generated or enhanced by these fusion stations. This local fusion station should also enable the interaction between these local units and a global information world.

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.

2D/3D Synthetic Vision Navigation Display

NASA Technical Reports Server (NTRS)

Prinzel, Lawrence J., III; Kramer, Lynda J.; Arthur, J. J., III; Bailey, Randall E.; Sweeters, jason L.

2008-01-01

Flight-deck display software was designed and developed at NASA Langley Research Center to provide two-dimensional (2D) and three-dimensional (3D) terrain, obstacle, and flight-path perspectives on a single navigation display. The objective was to optimize the presentation of synthetic vision (SV) system technology that permits pilots to view multiple perspectives of flight-deck display symbology and 3D terrain information. Research was conducted to evaluate the efficacy of the concept. The concept has numerous unique implementation features that would permit enhanced operational concepts and efficiencies in both current and future aircraft.

Mobility-Dependent Motion Planning for High Speed Robotic Vehicles

DTIC Science & Technology

2008-07-25

of the vehicle’s mobility in such type of terrain. Moreover, autonomous driv- ing of wheeled vehicles at high speeds adds a new level of complexity due...dynamic effects such as wheel slip, skidding, ballistic behavior, rollover, and vehicle-terrain interaction phenomena. Navigation algorithms must also...description of mobility was defined as the probability that for a given 6 ini ial v 10 ity at an initial po ition h robo will hav a non-n gative ve- loci y

Effects of a Velocity-Vector Based Command Augmentation System and Synthetic Vision System Terrain Portrayal and Guidance Symbology Concepts on Single-Pilot Performance

NASA Technical Reports Server (NTRS)

Liu, Dahai; Goodrich, Kenneth H.; Peak, Bob

2010-01-01

This study investigated the effects of synthetic vision system (SVS) concepts and advanced flight controls on the performance of pilots flying a light, single-engine general aviation airplane. We evaluated the effects and interactions of two levels of terrain portrayal, guidance symbology, and flight control response type on pilot performance during the conduct of a relatively complex instrument approach procedure. The terrain and guidance presentations were evaluated as elements of an integrated primary flight display system. The approach procedure used in the study included a steeply descending, curved segment as might be encountered in emerging, required navigation performance (RNP) based procedures. Pilot performance measures consisted of flight technical performance, perceived workload, perceived situational awareness and subjective preference. The results revealed that an elevation based generic terrain portrayal significantly improved perceived situation awareness without adversely affecting flight technical performance or workload. Other factors (pilot instrument rating, control response type, and guidance symbology) were not found to significantly affect the performance measures.

Quadtree of TIN: a new algorithm of dynamic LOD

NASA Astrophysics Data System (ADS)

Zhang, Junfeng; Fei, Lifan; Chen, Zhen

2009-10-01

Currently, Real-time visualization of large-scale digital elevation model mainly employs the regular structure of GRID based on quadtree and triangle simplification methods based on irregular triangulated network (TIN). TIN is a refined means to express the terrain surface in the computer science, compared with GRID. However, the data structure of TIN model is complex, and is difficult to realize view-dependence representation of level of detail (LOD) quickly. GRID is a simple method to realize the LOD of terrain, but contains more triangle count. A new algorithm, which takes full advantage of the two methods' merit, is presented in this paper. This algorithm combines TIN with quadtree structure to realize the view-dependence LOD controlling over the irregular sampling point sets, and holds the details through the distance of viewpoint and the geometric error of terrain. Experiments indicate that this approach can generate an efficient quadtree triangulation hierarchy over any irregular sampling point sets and achieve dynamic and visual multi-resolution performance of large-scale terrain at real-time.

Point- and line-based transformation models for high resolution satellite image rectification

NASA Astrophysics Data System (ADS)

Abd Elrahman, Ahmed Mohamed Shaker

Rigorous mathematical models with the aid of satellite ephemeris data can present the relationship between the satellite image space and the object space. With government funded satellites, access to calibration and ephemeris data has allowed the development and use of these models. However, for commercial high-resolution satellites, which have been recently launched, these data are withheld from users, and therefore alternative empirical models should be used. In general, the existing empirical models are based on the use of control points and involve linking points in the image space and the corresponding points in the object space. But the lack of control points in some remote areas and the questionable accuracy of the identified discrete conjugate points provide a catalyst for the development of algorithms based on features other than control points. This research, concerned with image rectification and 3D geo-positioning determination using High-Resolution Satellite Imagery (HRSI), has two major objectives. First, the effects of satellite sensor characteristics, number of ground control points (GCPs), and terrain elevation variations on the performance of several point based empirical models are studied. Second, a new mathematical model, using only linear features as control features, or linear features with a minimum number of GCPs, is developed. To meet the first objective, several experiments for different satellites such as Ikonos, QuickBird, and IRS-1D have been conducted using different point based empirical models. Various data sets covering different terrain types are presented and results from representative sets of the experiments are shown and analyzed. The results demonstrate the effectiveness and the superiority of these models under certain conditions. From the results obtained, several alternatives to circumvent the effects of the satellite sensor characteristics, the number of GCPs, and the terrain elevation variations are introduced. To meet the second objective, a new model named the Line Based Transformation Model (LBTM) is developed for HRSI rectification. The model has the flexibility to either solely use linear features or use linear features and a number of control points to define the image transformation parameters. Unlike point features, which must be explicitly defined, linear features have the advantage that they can be implicitly defined by any segment along the line. (Abstract shortened by UMI.)

Mapping landslide susceptibility using data-driven methods.

PubMed

Zêzere, J L; Pereira, S; Melo, R; Oliveira, S C; Garcia, R A C

2017-07-01

Most epistemic uncertainty within data-driven landslide susceptibility assessment results from errors in landslide inventories, difficulty in identifying and mapping landslide causes and decisions related with the modelling procedure. In this work we evaluate and discuss differences observed on landslide susceptibility maps resulting from: (i) the selection of the statistical method; (ii) the selection of the terrain mapping unit; and (iii) the selection of the feature type to represent landslides in the model (polygon versus point). The work is performed in a single study area (Silveira Basin - 18.2km 2 - Lisbon Region, Portugal) using a unique database of geo-environmental landslide predisposing factors and an inventory of 82 shallow translational slides. The logistic regression, the discriminant analysis and two versions of the information value were used and we conclude that multivariate statistical methods perform better when computed over heterogeneous terrain units and should be selected to assess landslide susceptibility based on slope terrain units, geo-hydrological terrain units or census terrain units. However, evidence was found that the chosen terrain mapping unit can produce greater differences on final susceptibility results than those resulting from the chosen statistical method for modelling. The landslide susceptibility should be assessed over grid cell terrain units whenever the spatial accuracy of landslide inventory is good. In addition, a single point per landslide proved to be efficient to generate accurate landslide susceptibility maps, providing the landslides are of small size, thus minimizing the possible existence of heterogeneities of predisposing factors within the landslide boundary. Although during last years the ROC curves have been preferred to evaluate the susceptibility model's performance, evidence was found that the model with the highest AUC ROC is not necessarily the best landslide susceptibility model, namely when terrain mapping units are heterogeneous in size and reduced in number. Copyright © 2017 Elsevier B.V. All rights reserved.

Ames Stereo Pipeline for Operation IceBridge

NASA Astrophysics Data System (ADS)

Beyer, R. A.; Alexandrov, O.; McMichael, S.; Fong, T.

2017-12-01

We are using the NASA Ames Stereo Pipeline to process Operation IceBridge Digital Mapping System (DMS) images into terrain models and to align them with the simultaneously acquired LIDAR data (ATM and LVIS). The expected outcome is to create a contiguous, high resolution terrain model for each flight that Operation IceBridge has flown during its eight year history of Arctic and Antarctic flights. There are some existing terrain models in the NSIDC repository that cover 2011 and 2012 (out of the total period of 2009 to 2017), which were made with the Agisoft Photoscan commercial software. Our open-source stereo suite has been verified to create terrains of similar quality. The total number of images we expect to process is around 5 million. There are numerous challenges with these data: accurate determination and refinement of camera pose when the images were acquired based on data logged during the flights and/or using information from existing orthoimages, aligning terrains with little or no features, images containing clouds, JPEG artifacts in input imagery, inconsistencies in how data was acquired/archived over the entire period, not fully reliable camera calibration files, and the sheer amount of data. We will create the majority of terrain models at 40 cm/pixel with a vertical precision of 10 to 20 cm. In some circumstances when the aircraft was flying higher than usual, those values will get coarser. We will create orthoimages at 10 cm/pixel (with the same caveat that some flights are at higher altitudes). These will differ from existing orthoimages by using the underlying terrain we generate rather than some pre-existing very low-resolution terrain model that may differ significantly from what is on the ground at the time of IceBridge acquisition.The results of this massive processing will be submitted to the NSIDC so that cryosphere researchers will be able to use these data for their investigations.

Geodetic imaging: A new tool for Mesoamerican archaeology

NASA Astrophysics Data System (ADS)

Carter, William E.; Shrestha, Ramesh L.; Fisher, Christopher; Leisz, Stephen

2012-10-01

On 15 May 2012, Honduran President Porfirio Lobo convened a press conference to announce that researchers mapping areas of the Mosquitia region of Honduras, using airborne light detection and ranging (lidar), had discovered what appeared to be an extensive complex of archaeological ruins hidden beneath the dense canopy of rain forest that shrouds the terrain [UTL Scientific, LLC, 2012]. President Lobo released preliminary images of the ruins derived from the airborne lidar observations (Figure 1a) but withheld information about their precise location so that measures could be taken to protect and preserve this newly discovered cultural heritage. The coordinates of the ruins, determined from the lidar observations with an accuracy of a few decimeters, will enable archaeological teams to use the Global Positioning System to navigate through the dense forest directly to features of interest.

The complex terrain of peer support in mental health: What does it all mean?

PubMed

Murphy, Rebecca; Higgins, Agnes

2018-05-24

Emerging from cumulative socio-political movements forged by persons with self-experience of mental health difficulties, since the 1970s the practice of peer support has rapidly developed within mental health care. Now revered as a critical component to recovery oriented mental health service, peer support features prominently in international mental health policy and practice (Penney, 2018; Watts & Higgins, 2017; Cyr et al., 2016; Stamou, 2014; Bassett et al., 2010). As a consequence of this extensive growth, the field of peer support is flooded with various models including, but not limited to, individual and collective models that can be face-to-face or online, and positioned within mainstream mental health services, and/or peer-run organisations. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Ice and debris in the fretted terrain, Mars

NASA Astrophysics Data System (ADS)

Lucchitta, B. K.

1984-02-01

Viking moderate and high resolution images along the northern highland margin have been monoscopically and stereoscopically examined in order to study the development of fretted terrain. Young debris aprons around mesas and debris in tributary channels create typical fretted morphologies identical to ancient fretted morphologies. This suggests that the debris-apron process operating relatively recently also shaped the fretted terrain of the past. The debris aprons were lubricated by interstitial ice derived from ground ice. Abundant collapse features suggest that ground ice existed and may have flowed in places. The fretting process has been active for a long period and may be active today. The location of debris aprons in two latitudinal belts may be controlled by atmospheric conditions that permit ice in the region to remain in the ground below depths of about one meter and temperatures warm enough for ice to flow.

Vision guided landing of an an autonomous helicopter in hazardous terrain

NASA Technical Reports Server (NTRS)

Johnson, Andrew E.; Montgomery, Jim

2005-01-01

Future robotic space missions will employ a precision soft-landing capability that will enable exploration of previously inaccessible sites that have strong scientific significance. To enable this capability, a fully autonomous onboard system that identifies and avoids hazardous features such as steep slopes and large rocks is required. Such a system will also provide greater functionality in unstructured terrain to unmanned aerial vehicles. This paper describes an algorithm for landing hazard avoidance based on images from a single moving camera. The core of the algorithm is an efficient application of structure from motion to generate a dense elevation map of the landing area. Hazards are then detected in this map and a safe landing site is selected. The algorithm has been implemented on an autonomous helicopter testbed and demonstrated four times resulting in the first autonomous landing of an unmanned helicopter in unknown and hazardous terrain.

Erosional landforms on the layered terrains in Valles Marineris

NASA Technical Reports Server (NTRS)

Komatsu, G.; Strom, R. G.; Gulick, V. C.; Parker, T. J.

1992-01-01

Many investigators have proposed potential lakes in Valles Marineris based on the relationship with outflow channels, and a proposed lacustrine origin of layered deposits. We have investigated the erosional style of the layered terrains and evaluated their potential origins as sedimentation in and erosional modification by these lakes. The erosional features that will be discussed are distributed in the central canyon area and classified into terraces and layered depressions. Many terraces can be explained by coastal erosion in lakes as well as by eolian erosion. The lack of terraces on the canyon walls is probably due to more recent sapping and mass wasting of materials with different mechanical response to erosion than the layered terrains. Catastrophic water discharges in Valles Marineris as hypothesized by an ocean model may have been the source of the lakes and the eventual catastrophic release of water from the canyons.

Automatic Match between Delimitation Line and Real Terrain Based on Least-Cost Path Analysis

NASA Astrophysics Data System (ADS)

Feng, C. Q.; Jiang, N.; Zhang, X. N.; Ma, J.

2013-11-01

Nowadays, during the international negotiation on separating dispute areas, manual adjusting is lonely applied to the match between delimitation line and real terrain, which not only consumes much time and great labor force, but also cannot ensure high precision. Concerning that, the paper mainly explores automatic match between them and study its general solution based on Least -Cost Path Analysis. First, under the guidelines of delimitation laws, the cost layer is acquired through special disposals of delimitation line and terrain features line. Second, a new delimitation line gets constructed with the help of Least-Cost Path Analysis. Third, the whole automatic match model is built via Module Builder in order to share and reuse it. Finally, the result of automatic match is analyzed from many different aspects, including delimitation laws, two-sided benefits and so on. Consequently, a conclusion is made that the method of automatic match is feasible and effective.

Topographic Features of Malyy Naryn River Watershed Based on Different Data

NASA Astrophysics Data System (ADS)

Li, M.; Chen, L.; Cui, Y.; Zhang, M.

2018-04-01

This paper researched the influence on the topographical characteristics of watersheds by setting different catchment area thresholds based on different data sets, namely ZY3 DSM, SRTM DEM and ASTER GDEM. Slope, hypsometric integral, river network density and river network discrepancy are analyzed and compared. The results are as follows: a) Three data sets all can express the same rough terrain characteristics and the same degree of watershed topography development; b) ZY3 DSM can reflect terrain information over the Malyy Naryn River watershed in most detail and it has the best expression effect on the terrain among the three data sets of ZY3 DSM, SRTM DEM and ASTER GDEM, followed by SRTM DEM, and the effect of ASTER GDEM is the worst; c) The similarity of river networks extracted by ZY3 DSM and SRTM DEM is the highest, and the similarity between ZY3 DSM and ASTER GDEM is the lowest one.

GPS test range mission planning

NASA Astrophysics Data System (ADS)

Roberts, Iris P.; Hancock, Thomas P.

The principal features of the Test Range User Mission Planner (TRUMP), a PC-resident tool designed to aid in deploying and utilizing GPS-based test range assets, are reviewed. TRUMP features time history plots of time-space-position information (TSPI); performance based on a dynamic GPS/inertial system simulation; time history plots of TSPI data link connectivity; digital terrain elevation data maps with user-defined cultural features; and two-dimensional coverage plots of ground-based test range assets. Some functions to be added during the next development phase are discussed.

Shaded Relief of Rio Sao Francisco, Brazil

NASA Image and Video Library

2000-02-14

This topographic image acquired by SRTM shows an area south of the Sao Francisco River in Brazil. The scrub forest terrain shows relief of about 400 meters (1300 feet). Areas such as these are difficult to map by traditional methods because of frequent cloud cover and local inaccessibility. This region has little topographic relief, but even subtle changes in topography have far-reaching effects on regional ecosystems. The image covers an area of 57 km x 79 km and represents one quarter of the 225 km SRTM swath. Colors range from dark blue at water level to white and brown at hill tops. The terrain features that are clearly visible in this image include tributaries of the Sao Francisco, the dark-blue branch-like features visible from top right to bottom left, and on the left edge of the image, and hills rising up from the valley floor. The San Francisco River is a major source of water for irrigation and hydroelectric power. Mapping such regions will allow scientists to better understand the relationships between flooding cycles, forestation and human influences on ecosystems. This shaded relief image was generated using topographic data from the Shuttle Radar Topography Mission. A computer-generated artificial light source illuminates the elevation data to produce a pattern of light and shadows. Slopes facing the light appear bright, while those facing away are shaded. On flatter surfaces, the pattern of light and shadows can reveal subtle features in the terrain. Shaded relief maps are commonly used in applications such as geologic mapping and land use planning. http://photojournal.jpl.nasa.gov/catalog/PIA02700

AERMOD: MODEL FORMULATION AND EVALUATION RESULTS

EPA Science Inventory

AERMOD is an advanced plume model that incorporates updated treatments of the boundary layer theory, understanding of turbulence and dispersion, and includes handling of terrain interactions. This paper presents an overview of AERMOD's features relative to ISCST3.

AERM...

A Novel Identification Methodology for the Coordinate Relationship between a 3D Vision System and a Legged Robot

PubMed Central

Chai, Xun; Gao, Feng; Pan, Yang; Qi, Chenkun; Xu, Yilin

2015-01-01

Coordinate identification between vision systems and robots is quite a challenging issue in the field of intelligent robotic applications, involving steps such as perceiving the immediate environment, building the terrain map and planning the locomotion automatically. It is now well established that current identification methods have non-negligible limitations such as a difficult feature matching, the requirement of external tools and the intervention of multiple people. In this paper, we propose a novel methodology to identify the geometric parameters of 3D vision systems mounted on robots without involving other people or additional equipment. In particular, our method focuses on legged robots which have complex body structures and excellent locomotion ability compared to their wheeled/tracked counterparts. The parameters can be identified only by moving robots on a relatively flat ground. Concretely, an estimation approach is provided to calculate the ground plane. In addition, the relationship between the robot and the ground is modeled. The parameters are obtained by formulating the identification problem as an optimization problem. The methodology is integrated on a legged robot called “Octopus”, which can traverse through rough terrains with high stability after obtaining the identification parameters of its mounted vision system using the proposed method. Diverse experiments in different environments demonstrate our novel method is accurate and robust. PMID:25912350

Catastrophic ice lake collapse in Aram Chaos, Mars

NASA Astrophysics Data System (ADS)

Roda, Manuel; Kleinhans, Maarten G.; Zegers, Tanja E.; Oosthoek, Jelmer H. P.

2014-07-01

Hesperian chaotic terrains have been recognized as the source of outflow channels formed by catastrophic outflows. Four main scenarios have been proposed for the formation of chaotic terrains that involve different amounts of water and single or multiple outflow events. Here, we test these scenarios with morphological and structural analyses of imagery and elevation data for Aram Chaos in conjunction with numerical modeling of the morphological evolution of the catastrophic carving of the outflow valley. The morphological and geological analyses of Aram Chaos suggest large-scale collapse and subsidence (1500 m) of the entire area, which is consistent with a massive expulsion of liquid water from the subsurface in one single event. The combined observations suggest a complex process starting with the outflow of water from two small channels, followed by continuous groundwater sapping and headward erosion and ending with a catastrophic lake rim collapse and carving of the Aram Valley, which is synchronous with the 2.5 Ga stage of the Ares Vallis formation. The water volume and formative time scale required to carve the Aram channels indicate that a single, rapid (maximum tens of days) and catastrophic (flood volume of 9.3 × 104 km3) event carved the outflow channel. We conclude that a sub-ice lake collapse model can best explain the features of the Aram Chaos Valley system as well as the time scale required for its formation.

A model of the extent and distribution of woody linear features in rural Great Britain.

PubMed

Scholefield, Paul; Morton, Dan; Rowland, Clare; Henrys, Peter; Howard, David; Norton, Lisa

2016-12-01

Hedges and lines of trees (woody linear features) are important boundaries that connect and enclose habitats, buffer the effects of land management, and enhance biodiversity in increasingly impoverished landscapes. Despite their acknowledged importance in the wider countryside, they are usually not considered in models of landscape function due to their linear nature and the difficulties of acquiring relevant data about their character, extent, and location. We present a model which uses national datasets to describe the distribution of woody linear features along boundaries in Great Britain. The method can be applied for other boundary types and in other locations around the world across a range of spatial scales where different types of linear feature can be separated using characteristics such as height or width. Satellite-derived Land Cover Map 2007 (LCM2007) provided the spatial framework for locating linear features and was used to screen out areas unsuitable for their occurrence, that is, offshore, urban, and forest areas. Similarly, Ordnance Survey Land-Form PANORAMA®, a digital terrain model, was used to screen out where they do not occur. The presence of woody linear features on boundaries was modelled using attributes from a canopy height dataset obtained by subtracting a digital terrain map (DTM) from a digital surface model (DSM). The performance of the model was evaluated against existing woody linear feature data in Countryside Survey across a range of scales. The results indicate that, despite some underestimation, this simple approach may provide valuable information on the extents and locations of woody linear features in the countryside at both local and national scales.

Intercomparison of 7 Planetary Boundary-Layer/Surface-Layer Physics Schemes over Complex Terrain for Battlefield Situational Awareness

DTIC Science & Technology

This study considers the performance of 7 of the Weather Research and Forecast model boundary-layer (BL) parameterization schemes in a complex...schemes performed best. The surface parameters, planetary BL structure, and vertical profiles are important for US Army Research Laboratory

Managing Construction Operations Visually: 3-D Techniques for Complex Topography and Restricted Visibility

ERIC Educational Resources Information Center

Rodriguez, Walter; Opdenbosh, Augusto; Santamaria, Juan Carlos

2006-01-01

Visual information is vital in planning and managing construction operations, particularly, where there is complex terrain topography and salvage operations with limited accessibility and visibility. From visually-assessing site operations and preventing equipment collisions to simulating material handling activities to supervising remotes sites…

Laboratory simulations of the atmospheric mixed-layer in flow over complex topography

EPA Science Inventory

A laboratory study of the influence of complex terrain on the interface between a well-mixed boundary layer and an elevated stratified layer was conducted in the towing-tank facility of the U.S. Environmental Protection Agency. The height of the mixed layer in the daytime boundar...

Adams-Based Rover Terramechanics and Mobility Simulator - ARTEMIS

NASA Technical Reports Server (NTRS)

Trease, Brian P.; Lindeman, Randel A.; Arvidson, Raymond E.; Bennett, Keith; VanDyke, Lauren P.; Zhou, Feng; Iagnemma, Karl; Senatore, Carmine

2013-01-01

The Mars Exploration Rovers (MERs), Spirit and Opportunity, far exceeded their original drive distance expectations and have traveled, at the time of this reporting, a combined 29 kilometers across the surface of Mars. The Rover Sequencing and Visualization Program (RSVP), the current program used to plan drives for MERs, is only a kinematic simulator of rover movement. Therefore, rover response to various terrains and soil types cannot be modeled. Although sandbox experiments attempt to model rover-terrain interaction, these experiments are time-intensive and costly, and they cannot be used within the tactical timeline of rover driving. Imaging techniques and hazard avoidance features on MER help to prevent the rover from traveling over dangerous terrains, but mobility issues have shown that these methods are not always sufficient. ARTEMIS, a dynamic modeling tool for MER, allows planned drives to be simulated before commands are sent to the rover. The deformable soils component of this model allows rover-terrain interactions to be simulated to determine if a particular drive path would take the rover over terrain that would induce hazardous levels of slip or sink. When used in the rover drive planning process, dynamic modeling reduces the likelihood of future mobility issues because high-risk areas could be identified before drive commands are sent to the rover, and drives planned over these areas could be rerouted. The ARTEMIS software consists of several components. These include a preprocessor, Digital Elevation Models (DEMs), Adams rover model, wheel and soil parameter files, MSC Adams GUI (commercial), MSC Adams dynamics solver (commercial), terramechanics subroutines (FORTRAN), a contact detection engine, a soil modification engine, and output DEMs of deformed soil. The preprocessor is used to define the terrain (from a DEM) and define the soil parameters for the terrain file. The Adams rover model is placed in this terrain. Wheel and soil parameter files can be altered in the respective text files. The rover model and terrain are viewed in Adams View, the GUI for ARTEMIS. The Adams dynamics solver calls terramechanics subroutines in FORTRAN containing the Bekker-Wong equations.

Are Titan's radial Labyrinth terrains surface expressions of large laccoliths?

NASA Astrophysics Data System (ADS)

Schurmeier, L.; Dombard, A. J.; Malaska, M.; Radebaugh, J.

2017-12-01

The Labyrinth terrain unit may be the one of the best examples of the surface expression of Titan's complicated history. They are characterized as highly eroded, dissected, and elevated plateaus and remnant ridges, with an assumed composition that is likely organic-rich based on radar emissivity. How these features accumulated organic-rich sediments and formed topographic highs by either locally uplifting or surviving pervasive regional deflation or erosion is an important question for understanding the history of Titan. There are several subsets of Labyrinth terrains, presumably with differing evolutionary histories and formation processes. We aim to explain the formation of a subset of Labyrinth terrain units informally referred to as "radial Labyrinth terrains." They are elevated and appear dome-like, circular in planform, have a strong radial dissection pattern, are bordered by Undifferentiated Plains units, and are found in the mid-latitudes. Based on their shape, clustering, and dimensions, we suggest that they may be the surface expression of large subsurface laccoliths. A recent study by Manga and Michaut (Icarus, 2017) explained Europa's lenticulae (pits, domes, spots) with the formation of saucer-shaped sills that form laccoliths around the brittle-ductile transition depth within the ice shell (1-5 km). Here, we apply the same scaling relationships and find that the larger size of radial labyrinth terrains with Titan's higher gravity implies deeper intrusion depths of around 20-40 km. This intrusion depth matches the expected brittle-ductile transition on Titan based on our finite element simulations and yield strength envelope analyses. We hypothesize that Titan's radial labyrinth terrains formed as cryovolcanic (water) intrusions that rose to the brittle-ductile transition within the ice shell where they spread horizontally, and uplifted the overlying ice. The organic-rich sedimentary cover also uplifted, becoming more susceptible to pluvial and fluvial erosion, and hence resulting in uplifted, highly eroded terrains within the Undifferentiated Plains unit. Since widespread evidence for cryovolcanism has been marginal on Titan, perhaps a large proportion of it is intrusive, expressed as radial Labyrinth terrains on Titan.

Vesta Mineralogy after Dawn Global Observations

NASA Technical Reports Server (NTRS)

ChristinaDeSanctis, Maria; Ammannito, E.; Capaccioni, F.; Cparia, M. T.; Carraro, F.; Fonte, S.; Frigeri, A.; Longobardo, A.; Marchi, S.; Palomba, E.;

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.

Characterisation of recirculation zones in complex terrain using multi-lidar measurements

NASA Astrophysics Data System (ADS)

Menke, R.; Mann, J.; Vasiljevic, N.

2017-12-01

Wind fields in complex terrain show a higher complexity compared to sites with simpler geometries. It is imperative to understand well the characteristics of complex flows to account for them during the site validation to ensure the wind turbines can withstand the local flow conditions. This study focuses on the description of recirculation zones occurring on lee sides of hills. The flow recirculation can have a significant impact on the success of wind energy projects since it represents one of the main contributors to the turbulence generation. An extensive dataset of observation of flow over complex terrain is available from the Perdigão 2017 field campaign (https://www.nature.com/news/world-s-largest-wind-mapping-project-spins-up-in-portugal-1.21481). A setup of 8 long-range WindScanners (Vasiljević et al., 2016), scanning lidars deployed by DTU performed RHI scans at several positions along two parallel ridges probing the flow field in two vertical planes, in addition data from several meteorological masts is available. With the above-mentioned lidar setup we achieved simultaneous dual-Doppler scans of the recirculation zone at three positions and simultaneous observations of recirculation behind two parallel ridges. Methods are developed to identify and define the extent of recirculation bubbles. Different parameters are defined to characterise the dimensions of the recirculation zone. The change of these parameters along the ridges is studied. In particular, the impact of atmospheric stability and the changes of the wind field at the position of the downwind ridge are investigated. Furthermore, the geometry of the recirculation zone for different wind directions and in connection to the upstream wind conditions is investigated.

WRF Improves Downscaled Precipitation During El Niño Events over Complex Terrain in Northern South America: Implications for Deforestation Studies

NASA Astrophysics Data System (ADS)

Rendón, A.; Posada, J. A.; Salazar, J. F.; Mejia, J.; Villegas, J.

2016-12-01

Precipitation in the complex terrain of the tropical Andes of South America can be strongly reduced during El Niño events, with impacts on numerous societally-relevant services, including hydropower generation, the main electricity source in Colombia. Simulating rainfall patterns and behavior in such areas of complex terrain has remained a challenge for regional climate models. Current data products such as ERA-Interim and other reanalysis and modelling products generally fail to correctly represent processes at scales that are relevant for these processes. Here we assess the added value to ERA-Interim by dynamical downscaling using the WRF regional climate model, including a comparison of different cumulus parameterization schemes. We found that WRF improves the representation of precipitation during the dry season of El Niño (DJF) events using a 1996-2014 observation period. Further, we use these improved capability to simulate an extreme deforestation scenario under El Niño conditions for an area in the central Andes of Colombia, where a big proportion of the country's hydropower is generated. Our results suggest that forests dampen the effects of El Niño on precipitation. In synthesis, our results illustrate the utility of regional modelling to improve data sources, as well as their potential for predicting the local-to-regional effects of global-change-type processes in regions with limited data availability.

Topoclimate effects on growing season length and montane conifer growth in complex terrain

DOE PAGES

Barnard, David M.; Barnard, H. R.; Molotch, N. P.

2017-05-23

Spatial variability in the topoclimate-driven linkage between forest phenology and tree growth in complex terrain is poorly understood, limiting our understanding of how ecosystems function as a whole. To characterize the influence of topoclimate on phenology and growth, we determined the start, end, and length of the growing season (GS start, GS end, and GSL, respectively) using the correlation between transpiration and evaporative demand, measured with sapflow. We then compared these metrics with stem relative basal area increment (relative BAI) at seven sites among elevation and aspects in a Colorado montane forest. As elevation increased, we found shorter GSL (–50more » d km –1) due to later GSstart (40 d km –1) and earlier GSend (–10 d km –1). North-facing sites had a 21 d shorter GSL than south-facing sites at similar elevations (i.e. equal to 200 m elevation difference on a given aspect). Growing season length was positively correlated with relative BAI, explaining 83% of the variance. This study shows that topography exerts strong environmental controls on GSL and thus forest growth. Here, given the climate-related dependencies of these controls, the results presented here have important implications for ecosystem responses to changes in climate and highlight the need for improved phenology representation in complex terrain.« less

Understanding thermal circulations and near-surface turbulence processes in a small mountain valley

NASA Astrophysics Data System (ADS)

Pardyjak, E.; Dupuy, F.; Durand, P.; Gunawardena, N.; Thierry, H.; Roubin, P.

2017-12-01

The interaction of turbulence and thermal circulations in complex terrain can be significantly different from idealized flat terrain. In particular, near-surface horizontal spatial and temporal variability of winds and thermodynamic variables can be significant event over very small spatial scales. The KASCADE (KAtabatic winds and Stability over CAdarache for Dispersion of Effluents) 2017 conducted from January through March 2017 was designed to address these issues and to ultimately improve prediction of dispersion in complex terrain, particularly during stable atmospheric conditions. We have used a relatively large number of sensors to improve our understanding of the spatial and temporal development, evolution and breakdown of topographically driven flows. KASCADE 2017 consisted of continuous observations and fourteen Intensive Observation Periods (IOPs) conducted in the Cadarache Valley located in southeastern France. The Cadarache Valley is a relatively small valley (5 km x 1 km) with modest slopes and relatively small elevation differences between the valley floor and nearby hilltops ( 100 m). During winter, winds in the valley are light and stably stratified at night leading to thermal circulations as well as complex near-surface atmospheric layering. In this presentation we present results quantifying spatial variability of thermodynamic and turbulence variables as a function of different large -scale forcing conditions (e.g., quiescent conditions, strong westerly flow, and Mistral flow). In addition, we attempt to characterize highly-regular nocturnal horizontal wind meandering and associated turbulence statistics.

Complex terrain experiments in the New European Wind Atlas.

PubMed

Mann, J; Angelou, N; Arnqvist, J; Callies, D; Cantero, E; Arroyo, R Chávez; Courtney, M; Cuxart, J; Dellwik, E; Gottschall, J; Ivanell, S; Kühn, P; Lea, G; Matos, J C; Palma, J M L M; Pauscher, L; Peña, A; Rodrigo, J Sanz; Söderberg, S; Vasiljevic, N; Rodrigues, C Veiga

2017-04-13

The New European Wind Atlas project will create a freely accessible wind atlas covering Europe and Turkey, develop the model chain to create the atlas and perform a series of experiments on flow in many different kinds of complex terrain to validate the models. This paper describes the experiments of which some are nearly completed while others are in the planning stage. All experiments focus on the flow properties that are relevant for wind turbines, so the main focus is the mean flow and the turbulence at heights between 40 and 300 m. Also extreme winds, wind shear and veer, and diurnal and seasonal variations of the wind are of interest. Common to all the experiments is the use of Doppler lidar systems to supplement and in some cases replace completely meteorological towers. Many of the lidars will be equipped with scan heads that will allow for arbitrary scan patterns by several synchronized systems. Two pilot experiments, one in Portugal and one in Germany, show the value of using multiple synchronized, scanning lidar, both in terms of the accuracy of the measurements and the atmospheric physical processes that can be studied. The experimental data will be used for validation of atmospheric flow models and will by the end of the project be freely available.This article is part of the themed issue 'Wind energy in complex terrains'. © 2017 The Authors.

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

PubMed

Evrendilek, Fatih

2007-12-12

This study aims at quantifying spatio-temporal dynamics of monthly mean dailyincident photosynthetically active radiation (PAR) over a vast and complex terrain such asTurkey. The spatial interpolation method of universal kriging, and the combination ofmultiple linear regression (MLR) models and map algebra techniques were implemented togenerate surface maps of PAR with a grid resolution of 500 x 500 m as a function of fivegeographical and 14 climatic variables. Performance of the geostatistical and MLR modelswas compared using mean prediction error (MPE), root-mean-square prediction error(RMSPE), average standard prediction error (ASE), mean standardized prediction error(MSPE), root-mean-square standardized prediction error (RMSSPE), and adjustedcoefficient of determination (R² adj. ). The best-fit MLR- and universal kriging-generatedmodels of monthly mean daily PAR were validated against an independent 37-year observeddataset of 35 climate stations derived from 160 stations across Turkey by the Jackknifingmethod. The spatial variability patterns of monthly mean daily incident PAR were moreaccurately reflected in the surface maps created by the MLR-based models than in thosecreated by the universal kriging method, in particular, for spring (May) and autumn(November). The MLR-based spatial interpolation algorithms of PAR described in thisstudy indicated the significance of the multifactor approach to understanding and mappingspatio-temporal dynamics of PAR for a complex terrain over meso-scales.

Are weather models better than gridded observations for precipitation in the mountains? (Invited)

NASA Astrophysics Data System (ADS)

Gutmann, E. D.; Rasmussen, R.; Liu, C.; Ikeda, K.; Clark, M. P.; Brekke, L. D.; Arnold, J.; Raff, D. A.

2013-12-01

Mountain snowpack is a critical storage component in the water cycle, and it provides drinking water for tens of millions of people in the Western US alone. This water store is susceptible to climate change both because warming temperatures are likely to lead to earlier melt and a temporal shift of the hydrograph, and because changing atmospheric conditions are likely to change the precipitation patterns that produce the snowpack. Current measurements of snowfall in complex terrain are limited in number due in part to the logistics of installing equipment in complex terrain. We show that this limitation leads to statistical artifacts in gridded observations of current climate including errors in precipitation season totals of a factor of two or more, increases in wet day fraction, and decreases in storm intensity. In contrast, a high-resolution numerical weather model (WRF) is able to reproduce observed precipitation patterns, leading to confidence in its predictions for areas without measurements and new observations support this. Running WRF for a future climate scenario shows substantial changes in the spatial patterns of precipitation in the mountains related to the physics of hydrometeor production and detrainment that are not captured by statistical downscaling products. The stationarity in statistical downscaling products is likely to lead to important errors in our estimation of future precipitation in complex terrain.

Topoclimate effects on growing season length and montane conifer growth in complex terrain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barnard, David M.; Barnard, H. R.; Molotch, N. P.

Spatial variability in the topoclimate-driven linkage between forest phenology and tree growth in complex terrain is poorly understood, limiting our understanding of how ecosystems function as a whole. To characterize the influence of topoclimate on phenology and growth, we determined the start, end, and length of the growing season (GS start, GS end, and GSL, respectively) using the correlation between transpiration and evaporative demand, measured with sapflow. We then compared these metrics with stem relative basal area increment (relative BAI) at seven sites among elevation and aspects in a Colorado montane forest. As elevation increased, we found shorter GSL (–50more » d km –1) due to later GSstart (40 d km –1) and earlier GSend (–10 d km –1). North-facing sites had a 21 d shorter GSL than south-facing sites at similar elevations (i.e. equal to 200 m elevation difference on a given aspect). Growing season length was positively correlated with relative BAI, explaining 83% of the variance. This study shows that topography exerts strong environmental controls on GSL and thus forest growth. Here, given the climate-related dependencies of these controls, the results presented here have important implications for ecosystem responses to changes in climate and highlight the need for improved phenology representation in complex terrain.« less

Geomorphological Map of the South Belet Region of Titan: An Exploration of Mid-Latitude-to-Pole Transition Zones

NASA Astrophysics Data System (ADS)

Schoenfeld, A.; Lopes, R.; Malaska, M.; Solomonidou, A.

2017-12-01

We carried out detailed geomorphological mapping of Titan's mid-latitude region south of the Belet Sand Sea. We used radar data collected by Cassini's Synthetic Aperture Radar (SAR) as our basemap, supplemented by images from VIMS, ISS, SARtopo, and microwave emissivity datasets. We mapped at a scale of 1:800,000 in all areas of the South Belet region covered by SAR swaths, taking into consideration the 300 m/pixel resolution of the swaths. For the mid-latitudes, we have defined five broad classes of terrains following Malaska et al. (2015). These terrain classes are craters, hummocky/mountainous, labyrinth, plains, and dunes. We have found that the hummocky/mountainous terrains are the oldest, with a radiometric signature consistent with icy materials. Dunes are the youngest units and return a radiometric signature consistent with organic sediments. We find that the South Belet region is covered primarily by the dune and plain units typical of Titan's mid-latitudes (Malaska et al. 2015). Previous mapping efforts of the mid-latitude regions of Titan (Lopes et al. 2016; Malaska et al. 2015) have indicated that these regions are predominately modified and influenced by aeolian activities. A plains unit designated "scalloped plains" is prominently featured between the 50°S and 60°S latitudes of this region. In this area we also find a terrain unit designated "dark irregular plains" that has been interpreted as damp materials saturated with liquid hydrocarbons (Malaska et al 2015; Hayes et al. 2008). We also note a higher occurrence of fluvial channels starting at this latitude zone and extending poleward. We suggest that these features demark the transition zone between mid-latitude/equatorial aeolian-dominated processes and fluvial-dominated processes prevailing at the poles.

Lidar Systems for Precision Navigation and Safe Landing on Planetary Bodies

NASA Technical Reports Server (NTRS)

Amzajerdian, Farzin; Pierrottet, Diego F.; Petway, Larry B.; Hines, Glenn D.; Roback, Vincent E.

2011-01-01

The ability of lidar technology to provide three-dimensional elevation maps of the terrain, high precision distance to the ground, and approach velocity can enable safe landing of robotic and manned vehicles with a high degree of precision. Currently, NASA is developing novel lidar sensors aimed at needs of future planetary landing missions. These lidar sensors are a 3-Dimensional Imaging Flash Lidar, a Doppler Lidar, and a Laser Altimeter. The Flash Lidar is capable of generating elevation maps of the terrain that indicate hazardous features such as rocks, craters, and steep slopes. The elevation maps collected during the approach phase of a landing vehicle, at about 1 km above the ground, can be used to determine the most suitable safe landing site. The Doppler Lidar provides highly accurate ground relative velocity and distance data allowing for precision navigation to the landing site. Our Doppler lidar utilizes three laser beams pointed to different directions to measure line of sight velocities and ranges to the ground from altitudes of over 2 km. Throughout the landing trajectory starting at altitudes of about 20 km, the Laser Altimeter can provide very accurate ground relative altitude measurements that are used to improve the vehicle position knowledge obtained from the vehicle navigation system. At altitudes from approximately 15 km to 10 km, either the Laser Altimeter or the Flash Lidar can be used to generate contour maps of the terrain, identifying known surface features such as craters, to perform Terrain relative Navigation thus further reducing the vehicle s relative position error. This paper describes the operational capabilities of each lidar sensor and provides a status of their development. Keywords: Laser Remote Sensing, Laser Radar, Doppler Lidar, Flash Lidar, 3-D Imaging, Laser Altimeter, Precession Landing, Hazard Detection

Development of LIDAR sensor systems for autonomous safe landing on planetary bodies

NASA Astrophysics Data System (ADS)

Amzajerdian, F.; Pierrottet, D.; Petway, L.; Vanek, M.

2017-11-01

Future NASA exploratory missions to the Moon and Mars will require safe soft-landings at the designated sites with a high degree of precision. These sites may include areas of high scientific value with relatively rough terrain with little or no solar illumination and possibly areas near pre-deployed assets. The ability of lidar technology to provide three-dimensional elevation maps of the terrain, high precision distance to the ground, and approach velocity can enable safe landing of large robotic and manned vehicles with a high degree of precision. Currently, NASA-LaRC is developing novel lidar sensors aimed at meeting NASA's objectives for future planetary landing missions under the Autonomous Landing and Hazard Avoidance (ALHAT) project. These lidar sensors are 3-Dimensional Imaging Flash Lidar, Doppler Lidar, and Laser Altimeter. The Flash Lidar is capable of generating elevation maps of the terrain identifying hazardous features such as rocks, craters, and steep slopes. The elevation maps collected during the approach phase between 1000 m to 500 m above the ground can be used to determine the most suitable safe landing site. The Doppler Lidar provides highly accurate ground velocity and distance data allowing for precision navigation to the selected landing site. Prior to the approach phase at altitudes of over 15 km, the Laser Altimeter can provide sufficient data for updating the vehicle position and attitude data from the Inertial Measurement Unit. At these higher altitudes, either the Laser Altimeter or the Flash Lidar can be used for generating a contour map of the terrain below for identifying known surface features such as craters for further reducing the vehicle relative position error.

Development of lidar sensor systems for autonomous safe landing on planetary bodies

NASA Astrophysics Data System (ADS)

Amzajerdian, F.; Pierrottet, D.; Petway, L.; Vanek, M.

2017-11-01

Future NASA exploratory missions to the Moon and Mars will require safe soft-landings at the designated sites with a high degree of precision. These sites may include areas of high scientific value with relatively rough terrain with little or no solar illumination and possibly areas near pre-deployed assets. The ability of lidar technology to provide three-dimensional elevation maps of the terrain, high precision distance to the ground, and approach velocity can enable safe landing of large robotic and manned vehicles with a high degree of precision. Currently, NASA-LaRC is developing novel lidar sensors aimed at meeting NASA's objectives for future planetary landing missions under the Autonomous Landing and Hazard Avoidance (ALHAT) project [1]. These lidar sensors are 3-Dimensional Imaging Flash Lidar, Doppler Lidar, and Laser Altimeter. The Flash Lidar is capable of generating elevation maps of the terrain identifying hazardous features such as rocks, craters, and steep slopes. The elevation maps collected during the approach phase between 1000 m to 500 m above the ground can be used to determine the most suitable safe landing site. The Doppler Lidar provides highly accurate ground velocity and distance data allowing for precision navigation to the selected landing site. Prior to the approach phase at altitudes of over 15 km, the Laser Altimeter can provide sufficient data for updating the vehicle position and attitude data from the Inertial Measurement Unit. At these higher altitudes, either the Laser Altimeter or the Flash Lidar can be used for generating a contour map of the terrain below for identifying known surface features such as craters for further reducing the vehicle relative position error.

Modeling of the "PLAN DA MATTUN" Archaeological Site Using a Combination of Different Sensors

NASA Astrophysics Data System (ADS)

Novák, D.; Tokarczyk, P.; Theiler, P. W.

2012-07-01

Plan da Mattun is located at ~2200 metre above sea level in the Tasna valley in alpine south-eastern Switzerland. In this remote location, finds dating back to the time of Ötzi (3000 B.C.) were discovered by archaeologists from the University of Zurich. For detailed investigations of the site as well as for documentation and visualization purposes the archaeologists were interested in digital models of the terrain and of certain boulders. In the presented project a digital terrain model of the rock stream located at the beginning of the valley was created, as well as detailed models of four larger boulders. These boulders average to 15 metre in height and width. The roughness of terrain makes it difficult to access certain areas and requires using multiple surveying techniques in order to cover all objects of interest. Therefore the digital terrain model was acquired using a combination of terrestrial laser scanning (TLS) and photogrammetric recording from an unmanned aerial vehicle (UAV). The larger boulders were reconstructed with a combination of TLS, terrestrial and UAV-based photogrammetry. With this approach it was possible to acquire a highaccuracy dataset over an area of 0.12 km2 under difficult conditions. The dataset includes a digital terrain model with a ground sampling distance of 10 cm and a relative accuracy of 2 cm in moderately sloped terrain. The larger boulders feature a resolution of 1 cm and a relative accuracy of 0.5 cm. The 3D data is to be used both for archaeological visualization purposes and for geological analysis of the rock stream.

Zircon U-Pb ages and Hf isotope data from the Kukuluma Terrain of the Geita Greenstone Belt, Tanzania Craton: Implications for stratigraphy, crustal growth and timing of gold mineralization

NASA Astrophysics Data System (ADS)

Kwelwa, S. D.; Sanislav, I. V.; Dirks, P. H. G. M.; Blenkinsop, T.; Kolling, S. L.

2018-03-01

The Geita Greenstone Belt is a late Archean greenstone belt located in the Tanzania Craton, trending approximately E-W and can be subdivided into three NW-SE trending terrains: the Kukuluma Terrain to the east, the Central Terrain in the middle and the Nyamullilima Terrain in the west. The Kukuluma Terrain, forms a NW-SE trending zone of complexly deformed sediments, intruded by the Kukuluma Intrusive Complex which, contains an early-syntectonic diorite-monzonite suite and a late-syntectonic granodiorite suite. Three gold deposits (Matandani, Kukuluma and Area 3W) are found along the contact between the Kukuluma Intrusive Complex and the sediments. A crystal tuff layer from the Kukuluma deposits returned an age of 2717 ± 12 Ma which can be used to constrain maximum sedimentation age in the area. Two granodiorite dykes from the same deposit and a small granodiorite intrusion found along a road cut yielded zircon ages of 2667 ± 17 Ma, 2661 ± 16 Ma and 2663 ± 11 Ma respectively. One mineralized granodiorite dyke from the Matandani deposit has an age of 2651 ± 14 Ma which can be used to constrain the maximum age of the gold mineralization in the area. The 2717 Ma crystal tuff has zircon grains with suprachondritic 176Hf/177Hf ratios (0.28108-0.28111 at 2717 Ma) and positive (+1.6 to +2.6) εHf values indicating derivation from juvenile mafic crust. Two of the granodiorite samples have suprachondritic 176Hf/177Hf ratios (avg. 0.28106 and 0.28107 at 2663 and 2651 Ma respectively) and nearly chondritic εHf values (avg. -0.5 and -0.3 respectively). The other two granodiorite samples have chondritic 176Hf/177Hf ratios (avg. 0.28104 and 0.28103 at 2667 and 2661 Ma respectively) and slightly negative εHf values (avg. -1.1 and -1.5 respectively). The new zircon age and isotope data suggest that the igneous activity in the Kukuluma Terrain involves a significant juvenile component and occurred within the 2720 to 2620 Ma period which, is the main period of crustal growth in the northern half of the Tanzania Craton.

Active formation of 'chaos terrain' over shallow subsurface water on Europa.

PubMed

Schmidt, B E; Blankenship, D D; Patterson, G W; Schenk, P M

2011-11-16

Europa, the innermost icy satellite of Jupiter, has a tortured young surface and sustains a liquid water ocean below an ice shell of highly debated thickness. Quasi-circular areas of ice disruption called chaos terrains are unique to Europa, and both their formation and the ice-shell thickness depend on Europa's thermal state. No model so far has been able to explain why features such as Conamara Chaos stand above surrounding terrain and contain matrix domes. Melt-through of a thin (few-kilometre) shell is thermodynamically improbable and cannot raise the ice. The buoyancy of material rising as either plumes of warm, pure ice called diapirs or convective cells in a thick (>10 kilometres) shell is insufficient to produce the observed chaos heights, and no single plume can create matrix domes. Here we report an analysis of archival data from Europa, guided by processes observed within Earth's subglacial volcanoes and ice shelves. The data suggest that chaos terrains form above liquid water lenses perched within the ice shell as shallow as 3 kilometres. Our results suggest that ice-water interactions and freeze-out give rise to the diverse morphologies and topography of chaos terrains. The sunken topography of Thera Macula indicates that Europa is actively resurfacing over a lens comparable in volume to the Great Lakes in North America. ©2011 Macmillan Publishers Limited. All rights reserved

Evidence for Possible Exposed Water Ice Deposits in Martian Low Latitude Chasms and Chaos

NASA Technical Reports Server (NTRS)

Leovy, C.; Wood, S. E.; Catling, D.; Montgomery, D. R.; Moore, J.; Barnhart, C.; Ginder, E.; Louie, M.

2004-01-01

A light-toned interior layer deposit (ILD) on the floor of the deep martian depression Juventae Chasma is found to have a relatively high thermal inertia approx. 500 J m(exp -2) s(exp -1/2) K(exp -1). This could imply rock, but is also similar to the average value of thermal inertia found for north polar layered deposits. Furthermore, ILD-B is found to exhibit a bluff and terrace structure . A terrace structure arises naturally in model simulations of the sublimation of large ice deposits. Such a staircase terrain, of course, is a further characteristic of north polar layered terrain. Morphological similarity, thermal inertia in the range of thermal inertias of the north polar cap layered terrain, and relatively high albedo lead us to propose that the ILD-B may consist of residual water ice partially covered by, and perhaps mixed with, varying amounts of dust or sand. Other ILDs (A-C) are also found in Juventae Chasma. While these ILDs lack the close morphological resemblance to the north polar cap, they share many other common features and appear to be part of the same formation. Similar ILDs are found in chaotic terrain elsewhere in the martian tropics. This leads us to propose that water ice may exist in the martian tropics today and may be implicit in the formation of chaotic terrain.

Ray craters on Ganymede: Implications for cratering apex-antapex asymmetry and surface modification processes

NASA Astrophysics Data System (ADS)

Xu, Luyuan; Hirata, Naoyuki; Miyamoto, Hideaki

2017-10-01

As the youngest features on Ganymede, ray craters are useful in revealing the sources of recent impactors and surface modification processes on the satellite. We examine craters with D > 10 km on Ganymede from images obtained by the Voyager and Galileo spacecraft to identify ray craters and study their spatial distributions. Furthermore, we carefully select images of appropriate solar and emission angles to obtain unbiased ray crater densities. As a result, we find that the density of large ray craters (D > 25 km) on the bright terrain exhibits an apex-antapex asymmetry, and its degree of asymmetry is much lower than the theoretical estimation for ecliptic comets. For large craters (D > 25 km), ecliptic comets ought to be less important than previously assumed, and a possible explanation is that nearly isotropic comets may play a more important role on Ganymede than previously thought. We also find that small ray craters (10 km < D < 25 km) on the bright terrain and ray craters (D > 10 km) on the dark terrain show no apex-antapex asymmetry. We interpret that the distribution difference between the terrain types comes from preferential thermal sublimation on the dark terrain, while the distribution difference between large and small ray craters suggests that rays of small craters are more readily erased by some surface modification processes, such as micrometeorite gardening.

LRC-1969-B701_P-07140

NASA Image and Video Library

1969-09-24

Donald Hewes at Lunar Landing Research Facility (LLRF). Donald Hewes, head of the Spacecraft Research Branch, managed the facility. Piles of cinders simulated the lunar craters and terrain features. Published in the book " A Century at Langley" by Joseph Chambers. pg. 97

Simulations of surface winds at the Viking Lander sites using a one-level model

NASA Technical Reports Server (NTRS)

Bridger, Alison F. C.; Haberle, Robert M.

1992-01-01

The one-level model developed by Mass and Dempsey for use in predicting surface flows in regions of complex terrain was adapted to simulate surface flows at the Viking lander sites on Mars. In the one-level model, prediction equations for surface winds and temperatures are formulated and solved. Surface temperatures change with time in response to diabatic heating, horizontal advection, adiabatic heating and cooling effects, and horizontal diffusion. Surface winds can change in response to horizontal advection, pressure gradient forces, Coriolis forces, surface drag, and horizontal diffusion. Surface pressures are determined by integration of the hydrostatic equation from the surface to some reference level. The model has successfully simulated surface flows under a variety of conditions in complex-terrain regions on Earth.

Large-scale deep-water seafloor mapping from the Rockall to the Hatton basins, NE Atlantic

NASA Astrophysics Data System (ADS)

Monteys, X.; Thébaudeau, B.; Murcia, C.; Duncan, N.

2016-02-01

Multibeam data acquired in 2000 and 2001 during the Irish National Seabed Survey (INSS) are used for the first detailed investigation of the seabed geomorphology and sediment type in the Hatton-Rockall basin area of the North East Atlantic Ocean, covering an area of approximately 80,000 km². The original multibeam survey produced bathymetric and backscatter datasets that allowed the creation of a Digital Terrain Models of approximately 50 m in resolution in water depths between 500 and 3500 m. Near-surface sediments for the entire region haven been classified using features derived from multibeam angular backscatter data (12kHz) and robust unsupervised clustering techniques. Additionally, sub bottom data imaging the shallow stratigraphy and geomagnetic measurements collected at the time of the MBES survey are combined to further characterise some of the features identified. The features presented in detail include parts of the Hatton and Gardar contourite drifts, volcanic mounds identified by their morphology and magnetic signature, deep-water coral mounds, iceberg scours as well as canyons, gullies and escarpments along and down the slopes of the banks and mounds. This study highlights for the first time the variety and complexity of the seafloor present at the seabed in the Irish Hatton-Rockall basin area

WRF simulation over complex terrain during a southern California wildfire event

NASA Astrophysics Data System (ADS)

Lu, W.; Zhong, S.; Charney, J. J.; Bian, X.; Liu, S.

2012-03-01

In October 2007, the largest wildfire-related evacuation in California's history occurred as severe wildfires broke out across southern California. Smoke from these wildfires contributed to elevated pollutant concentrations in the atmosphere, affecting air quality in a vast region of the western United States. High-resolution numerical simulations were performed using the Weather Research and Forecast (WRF) model to understand the atmospheric conditions during the wildfire episode and how the complex circulation patterns might affect smoke transport and dispersion. The simulated meteorological fields were validated using surface and upper air observations in California and Nevada. To distinguish the performance of the WRF in different geographic regions, the surface stations were grouped into coastal sites, valley and basin sites, and mountain sites, and the results for the three categories were analyzed and intercompared. For temperature and moisture, the mountain category has the best agreement with the observations, while the coastal category was the worst. For wind, the model performance for the three categories was very similar. The flow patterns over complex terrain were also analyzed under different synoptic conditions and the possible impact of the terrain on smoke and pollutant pathways is analyzed by employing a Lagrangian Particle Dispersion Model. When high mountains prevent the smoke from moving inland, the mountain passes act as active pathways for smoke transport; meanwhile, chimney effect helps inject the pollutants to higher levels, where they are transported regionally. The results highlight the role of complex topography in the assessment of the possible smoke transport patterns in the region.

Deep resistivity sounding studies in detecting shear zones: A case study from the southern granulite terrain of India

NASA Astrophysics Data System (ADS)

Singh, S. B.; Stephen, Jimmy

2006-10-01

The resistivity signatures of the major crustal scale shear zones that dissect the southern granulite terrain (SGT) of South India into discrete geological fragments have been investigated. Resistivity structures deduced from deep resistivity sounding measurements acquired with a 10 km long Schlumberger spreads yield significant insights into the resistivity distribution within the E-W trending shear system comprising the Moyar-Bhavani-Salem-Attur shear zone (MBSASZ) and Palghat-Cauvery shear zone (PCSZ). Vertical and lateral extensions of low resistivity features indicate the possible existence of weak zones at different depths throughout the shear zones. The MBSASZ characterized by very low resistivity in its deeper parts (>2500 m), extends towards the south with slightly higher resistivities to encompass the PCSZ. A major resistivity transition between the northern and southern parts is evident in the two-dimensional resistivity images. The northern Archaean granulite terrain exhibits a higher resistivity than the southern Neoproterozoic granulite terrain. Though this resistivity transition is not clear at greater depths, the extension of low resistivity zones has been well manifested. It is speculated here that a network of crustal scale shear zones in the SGT may have influenced the strength of the lithosphere.

The First Six Months of Iapetus Observations by the Cassini ISS Camera

NASA Technical Reports Server (NTRS)

Denk, T.; Neukum, G.; Helfenstein, P.; Thomas, P. C.; Turtle, E. P.; McEwen, A. S.; Roatsch, T.; Veverka, J.

2005-01-01

Since Saturn arrival in June 2004, Iapetus has been studied intensively by the Cassini ISS camera [1] at various ranges. The first of two relatively close flybys in the primary mission occurred on Dec 31, 2004 at an altitude of approx.123,400 km over the northern leading hemisphere, resulting in images with a minimum pixel scale of 740 m. Detailed results of this flyby are given in [2], while this abstract covers the observations obtained earlier. Among the most important discoveries are: (a) Four giant impact basins with diameters between 390 and 550 km were detected, three of them are located in the dark terrain [3]. (b) Data revealed a >1300 km long ridge that marks exactly Iapetus' equator within the dark terrain. Individual mountains within the western part of the ridge reach heights of approx.20 km over surrounding terrain [3]. (c) Impact craters were confirmed to be the main geological feature within the dark terrain and at high southern latitudes. (d) There are numerous craters with dark walls roughly facing towards the central parts of the dark hemisphere [3]. (e) Almost all parts of Iapetus have been imaged at least at low resolution (< 60 km/pxl).

The topography of Ceres and implications for the formation of linear surface structures

NASA Astrophysics Data System (ADS)

Buczkowski, D.; Otto, K.; Ruesch, O.; Scully, J. E. C.; Williams, D. A.; Mest, S. C.; Schenk, P.; Jaumann, R.; Nathues, A.; Preusker, F.; Park, R. S.; Raymond, C. A.; Russell, C. T.

2015-12-01

NASA's Dawn spacecraft began orbiting the dwarf planet Ceres in April 2015. Framing Camera data from the Approach (1.3 km/px) and Survey (415 m/px) orbits include digital terrain models derived from processing stereo images. These models have supported various scientific studies of the surface. The eastern hemisphere of Ceres is topographically higher than the western hemisphere. Some of linear structures on Ceres (which include grooves, pit crater chains, fractures and troughs) appear to be radial to the large basins Urvara and Yalode, and most likely formed due to impact processes. However, set of regional linear structures (RLS) that do not have any obvious relationship to impact craters are found on the eastern hemisphere topographic high region. Many of the longer RLS are comprised of smaller structures that have linked together, suggestive of en echelon fractures. Polygonal craters, theorized to form when pervasive subsurface fracturing affects crater formation [1], are widespread on Ceres [2], and those proximal to the RLS have straight crater rims aligned with the grooves and troughs, suggesting that the RLS are fracture systems. A cross-section of one RLS is displayed in FC images of the Occator crater wall. Comparing these images to the digital terrain models show 1) that the structure dips ~60º and 2) there is downward motion on the hanging wall, implying normal faulting. The digital terrain models also reveal the presence of numerous positive relief features with sub-circular shapes. These dome-like features have been tentatively interpreted as volcanic/magmatic features [3]; other possibilities include salt domes. Analog models of domal uplift in areas of regional extension [4] predict patterns of linear structures similar to those observed in the RLS near Occator. Utilizing topography data provided by the Ceres digital terrain models, we assess the relationship between the RLS and nearby domes and topographic high regions to determine the mechanism by which the RLS may have formed. [1] Thomas, P.C. et al. (1999) Icarus, doi: 10.1006/icar.1999.6121 [2] Otto et al. (2015) EPSC2015-284 [3] Ruesch et al. [this meeting] [4] Sims et al. (2013) AAPG Bulletin, doi: 10.1306/02101209136

Transient post-glacial processes on Mars: Geomorphologic evidence for a paraglacial period

NASA Astrophysics Data System (ADS)

Jawin, Erica R.; Head, James W.; Marchant, David R.

2018-07-01

On Earth a transitional phase between glacial and interglacial periods is referred to as the paraglacial period. This period immediately postdates glacial retreat and is characterized by ice removal, glacial unloading, and the exposure of steep slopes and large sediment stores. These responses led to the development of a suite of morphologic units (e.g., talus cones, gullies, sackungen, and polygons) which, when observed together, are indicative of the paraglacial period. A similar period of transitional climate and deglaciation is identified on Mars in the Late Amazonian, characterized by the association of features in a glaciated 10.6 km diameter mid-latitude crater. This crater contains concentric crater fill (CCF) formed by debris-covered glaciers, as well as a suite of stratigraphically younger geomorphic units (e.g., spatulate depressions, washboard terrain, gullies, and polygonal terrain) that are all indicative of the local environmental response to deglaciation. These features are interpreted to represent a geologically recent martian paraglacial period within this crater. The morphology and relative stratigraphic relationships among these paraglacial features are described in order to assess the processes operating during deglaciation and to document the recent history of glaciation on Mars: spatulate depressions formed by the differential sublimation of pure glacial ice near the base of the crater wall; subsequently, due to the loss of basal support and steepened slopes, remnant ice on the crater wall began to flow downhill, and formed transverse crevasses that created washboard terrain. Continuous thermal cycling of sediment-mantled ice on crater walls created fractures that formed polygonal terrain. During this time and after, gullies formed by the transport of sediment downslope from crater rim alcoves. Analyses of modeled obliquity variations suggest that the paraglacial period could have operated within the last ∼5 Myr and may still be ongoing, suggesting that the current martian paraglacial period is much longer in duration than typical paraglacial periods on Earth. Understanding the nature and sequence of paraglacial activity can help to identify variations in climate in recent Mars history.

Mapping the Oman Ophiolite using TM data

NASA Technical Reports Server (NTRS)

Abrams, Michael

1987-01-01

Ophiolite terrains, considered to be the onland occurrences of oceanic crust, host a number of types of mineral deposits: volcanogenic massive sulfides, podiform chromite, and asbestos. Thematic Mapper data for the Semail Ophiolite in Oman were used to separate and map ultramafic lithologies hosting these deposits, including identification of the components of the extrusive volcanic sequence, mapping of serpentinization due to various tectonic processes, and direct identification of gossans. Thematic Mapper data were found to be extremely effective for mapping in this terrain due to the excellent spatial resolution and the presence of spectral bands which allow separation of the pertinent mineralogically caused spectral features associated with the rock types of interest.

A Comparison of Two Path Planners for Planetary Rovers

NASA Technical Reports Server (NTRS)

Tarokh, M.; Shiller, Z.; Hayati, S.

1999-01-01

The paper presents two path planners suitable for planetary rovers. The first is based on fuzzy description of the terrain, and genetic algorithm to find a traversable path in a rugged terrain. The second planner uses a global optimization method with a cost function that is the path distance divided by the velocity limit obtained from the consideration of the rover static and dynamic stability. A description of both methods is provided, and the results of paths produced are given which show the effectiveness of the path planners in finding near optimal paths. The features of the methods and their suitability and application for rover path planning are compared

Satellite radars for geologic mapping in tropical regions

NASA Technical Reports Server (NTRS)

Ford, J. P.; Sabins, F. F.

1987-01-01

This paper presents interpretations of the satellite radar images of cloud-covered portions of Indonesia and Amazonia obtained from NASA's Shuttle imaging radar experiments in 1981 (SIR-A) and 1984 (SIR-B). It was found that different terrain categories observed from distinctive image textures correlate well with major lithologic associations. The images show geologic structures at regional and local scales. The SIR-B images of East Kalimantan, Indonesia, reveal structural features and terrain distributions that had been overlooked or not perceived in previous surface mapping. Variability in radar response from the vegetation cover is interpretable only in coastal areas or alluvial areas that are relatively level.

Pacific Northwest (PNW) Hydrologic Landscape (HL) polygons and HL code

EPA Pesticide Factsheets

A five-letter hydrologic landscape code representing five indices of hydrologic form that are related to hydrologic function: climate, seasonality, aquifer permeability, terrain, and soil permeability. Each hydrologic assessment unit is classified by one of the 81 different five-letter codes representing these indices. Polygon features in this dataset were created by aggregating (dissolving boundaries between) adjacent, similarly-coded hydrologic assessment units. Climate Classes: V-Very wet, W-Wet, M-Moist, D-Dry, S-Semiarid, A-Arid. Seasonality Sub-Classes: w-Fall or winter, s-Spring. Aquifer Permeability Classes: H-High, L-Low. Terrain Classes: M-Mountain, T-Transitional, F-Flat. Soil Permeability Classes: H-High, L-Low.

An in-depth study of Marcia Crater, Vesta

NASA Astrophysics Data System (ADS)

Hiesinger, Harald; Ruesch, Ottaviano; Williams, David A.; Nathues, Andreas; Prettyman, Thomas H.; Tosi, Frederico; De Sanctis, M. Christina; Scully, Jennifer E. C.; Schenk, Paul M.; Aileen Yingst, R.; Denevi, Bret W.; Jaumann, Ralf; Raymond, Carol A.; Russell, Chris T.

2014-05-01

After visiting the second most massive asteroid Vesta from July 2011 to September 2012, the Dawn spacecraft is now on its way to asteroid Ceres. Dawn observed Vesta with three instruments: the German Framing Camera (FC), the Italian Visible and InfraRed mapping spectrometer (VIR), and the American Gamma Ray and Neutron Detector (GRaND) [1]. Marcia crater (190°E, 10°N; 68 x 58 km) is the largest of three adjacent impact structures: Marcia (youngest), Calpurnia, and Minucia (oldest). It is the largest well-preserved post-Rheasilvia impact crater, shows a complex geology [2], is young [2], exhibits evidence for gully-like mass wasting [3], contains the largest location of pitted terrain [4], has smooth impact melt ponds [5], shows enhanced spectral pyroxene signatures on its inner walls [2], and has low abundances of OH and H in comparison to the surrounding low-albedo terrain [6, 7]. Geophysically, the broad region of Marcia and Calpurnia craters is characterized by a higher Bouguer gravity, indicating denser material [9]. Williams et al. [2] have produced a detailed geologic map of Marcia crater and the surrounding terrain. They identified several units within Marcia crater, including bright crater material, pitted terrain, and smooth material. Units outside Marcia, include undivided crater ejecta material, bright lobate material, dark lobate material, and dark crater ray material [2]. Because of its extensive ejecta and fresh appearance, the Marcia impact defines a major stratigraphic event, postdating the Rheasilvia impact [2]. However, the exact age of Marcia crater is still under debate. Compositionally, Marcia crater is characterized by higher iron abundances, which were interpreted as more basaltic-eucrite-rich materials suggesting that this region has not been blanketed by diogenitic materials from large impact events [10, 11]. Using FC data, [13] identified "gray material" associated with the ejecta blanket of Marcia crater. This material is characterized by a 0.75-mm reflectance of ~15%, a shallow visible slope, and a weak R(0.75 µm)/R(0.92 µm) ratio [12], which is still high compared to immediately adjacent terrains. The most prominent thermal feature in Marcia is the pitted terrain on its floor [8]. Temperatures of the pitted floor of Marcia are significantly lower than in the surrounding terrains, when observed under similar solar illumination. Denevi et al. [4] argued that the morphology and geologic setting are consistent with rapid degassing of volatile-bearing materials following an impact, which would lead to an increased local density and/or a higher thermal conductivity [8]. References: [1] Russell et al. (2007), Earth Moon Planets 101; [2] Williams et al. (2014), submitted to Icarus; [3] Scully et al. (2013), LPSC 45; [4] Denevi et al. (2012), Science 338; [5] Williams, D.A., et al. (2013) PSS, in press, j.pss.2013.06.017 [6] De Sanctis et al. (2012b) Astrophys. J. Lett. 758; [7] Prettyman et al. (2012), Science 338; [8] Tosi et al. (2014), submitted to Icarus; [9] Konopliv et al. (2013) Icarus, in press; [10] Yamashita et al. (2013), Met. Planet. Sci. 48; [11] Prettyman et al. (2013), Met. Planet. Sci. 48; [12] Reddy et al. (2012), Science 336

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…

Post-Observation Conferences with Bilingual Pre-Service Teachers: Revoicing and Rehearsing

ERIC Educational Resources Information Center

Wall, Dorothy J.; Hurie, Andrew H.

2017-01-01

Pre-service teachers need support in developing their teacher identities as they navigate the uncertain and complex terrain of student teaching and face the pressures of high-stakes accountability. This support is particularly important for bilingual pre-service teachers as they negotiate the many complexities of the bilingual classroom, and as…

Viscous relaxation as a prerequisite for tectonic resurfacing on Ganymede: Insights from numerical models of lithospheric extension

USGS Publications Warehouse

Bland, Michael T.; McKinnon, William B.

2018-01-01

Ganymede’s bright terrain formed during a near-global resurfacing event (or events) that produced both heavily tectonized and relatively smooth terrains. The mechanism(s) by which resurfacing occurred on Ganymede (e.g., cryovolcanic or tectonic), and the relationship between the older, dark and the younger, bright terrain are fundamental to understanding the geological evolution of the satellite. Using a two-dimensional numerical model of lithospheric extension that has previously been used to successfully simulate surface deformation consistent with grooved terrain morphologies, we investigate whether large-amplitude preexisting topography can be resurfaced (erased) by extension (i.e., tectonic resurfacing). Using synthetically produced initial topography, we show that when the total relief of the initial topography is larger than 25–50 m, periodic groove-like structures fail to form. Instead, extension is localized in a few individual, isolated troughs. These results pose a challenge to the tectonic resurfacing hypothesis. We further investigate the effects of preexisting topography by performing suites of simulations initialized with topography derived from digital terrain models of Ganymede’s surface. These include dark terrain, fresh (relatively deep) impact craters, smooth bright terrain, and a viscously relaxed impact crater. The simulations using dark terrain and fresh impact craters are consistent with our simulations using synthetic topography: periodic groove-like deformation fails to form. In contrast, when simulations were initialized with bright smooth terrain topography, groove-like deformation results from a wide variety of heat flow and surface temperature conditions. Similarly, when a viscously relaxed impact crater was used, groove-like structures were able to form during extension. These results suggest that tectonic resurfacing may require that the amplitude of the initial topography be reduced before extension begins. We emphasize that viscous relaxation may be the key to enabling tectonic resurfacing, as the heat fluxes associated with groove terrain formation are also capable of reducing crater topography through viscous relaxation. For long-wavelength topography (large craters) viscous relaxation is unavoidable. We propose that the resurfacing of Ganymede occurred through a combination of viscous relaxation, tectonic resurfacing, cryovolcanism and, at least in a few cases, band formation. Variations in heat flow and strain magnitudes across Ganymede likely produced the complex variety of terrain types currently observed.

Viscous relaxation as a prerequisite for tectonic resurfacing on Ganymede: Insights from numerical models of lithospheric extension

NASA Astrophysics Data System (ADS)

Bland, Michael T.; McKinnon, William B.

2018-05-01

Ganymede's bright terrain formed during a near-global resurfacing event (or events) that produced both heavily tectonized and relatively smooth terrains. The mechanism(s) by which resurfacing occurred on Ganymede (e.g., cryovolcanic or tectonic), and the relationship between the older, dark and the younger, bright terrain are fundamental to understanding the geological evolution of the satellite. Using a two-dimensional numerical model of lithospheric extension that has previously been used to successfully simulate surface deformation consistent with grooved terrain morphologies, we investigate whether large-amplitude preexisting topography can be resurfaced (erased) by extension (i.e., tectonic resurfacing). Using synthetically produced initial topography, we show that when the total relief of the initial topography is larger than 25-50 m, periodic groove-like structures fail to form. Instead, extension is localized in a few individual, isolated troughs. These results pose a challenge to the tectonic resurfacing hypothesis. We further investigate the effects of preexisting topography by performing suites of simulations initialized with topography derived from digital terrain models of Ganymede's surface. These include dark terrain, fresh (relatively deep) impact craters, smooth bright terrain, and a viscously relaxed impact crater. The simulations using dark terrain and fresh impact craters are consistent with our simulations using synthetic topography: periodic groove-like deformation fails to form. In contrast, when simulations were initialized with bright smooth terrain topography, groove-like deformation results from a wide variety of heat flow and surface temperature conditions. Similarly, when a viscously relaxed impact crater was used, groove-like structures were able to form during extension. These results suggest that tectonic resurfacing may require that the amplitude of the initial topography be reduced before extension begins. We emphasize that viscous relaxation may be the key to enabling tectonic resurfacing, as the heat fluxes associated with groove terrain formation are also capable of reducing crater topography through viscous relaxation. For long-wavelength topography (large craters) viscous relaxation is unavoidable. We propose that the resurfacing of Ganymede occurred through a combination of viscous relaxation, tectonic resurfacing, cryovolcanism and, at least in a few cases, band formation. Variations in heat flow and strain magnitudes across Ganymede likely produced the complex variety of terrain types currently observed.

Learning from Demonstration for Autonomous Navigation in Complex Unstructured Terrain

DTIC Science & Technology

2010-06-24

unstructured terrain Seraji and Howard, 2002, Huertas et al., 2005, Biesiadecki and Maimone, 2006] The common thread amongst these approaches is that they con...can be gathered either of- fline [ Seraji and Howard, 2002, Howard et al., 2007] or online [Thrun et al., 2006, Sun et al., 2007] by ob- serving where... Fe = F∗ = ~0; foreach P ie do P i∗ = planLossAugPath(start(P i e), goal(P ie), M); foreach x ∈ P ie do Fe + = Fe + Fx; foreach x ∈ P i∗ do F∗ = F∗ + Fx

Semi-automatic mapping of cultural heritage from airborne laser scanning using deep learning

NASA Astrophysics Data System (ADS)

Due Trier, Øivind; Salberg, Arnt-Børre; Holger Pilø, Lars; Tonning, Christer; Marius Johansen, Hans; Aarsten, Dagrun

2016-04-01

This paper proposes to use deep learning to improve semi-automatic mapping of cultural heritage from airborne laser scanning (ALS) data. Automatic detection methods, based on traditional pattern recognition, have been applied in a number of cultural heritage mapping projects in Norway for the past five years. Automatic detection of pits and heaps have been combined with visual interpretation of the ALS data for the mapping of deer hunting systems, iron production sites, grave mounds and charcoal kilns. However, the performance of the automatic detection methods varies substantially between ALS datasets. For the mapping of deer hunting systems on flat gravel and sand sediment deposits, the automatic detection results were almost perfect. However, some false detections appeared in the terrain outside of the sediment deposits. These could be explained by other pit-like landscape features, like parts of river courses, spaces between boulders, and modern terrain modifications. However, these were easy to spot during visual interpretation, and the number of missed individual pitfall traps was still low. For the mapping of grave mounds, the automatic method produced a large number of false detections, reducing the usefulness of the semi-automatic approach. The mound structure is a very common natural terrain feature, and the grave mounds are less distinct in shape than the pitfall traps. Still, applying automatic mound detection on an entire municipality did lead to a new discovery of an Iron Age grave field with more than 15 individual mounds. Automatic mound detection also proved to be useful for a detailed re-mapping of Norway's largest Iron Age grave yard, which contains almost 1000 individual graves. Combined pit and mound detection has been applied to the mapping of more than 1000 charcoal kilns that were used by an iron work 350-200 years ago. The majority of charcoal kilns were indirectly detected as either pits on the circumference, a central mound, or both. However, kilns with a flat interior and a shallow ditch along the circumference were often missed by the automatic detection method. The successfulness of automatic detection seems to depend on two factors: (1) the density of ALS ground hits on the cultural heritage structures being sought, and (2) to what extent these structures stand out from natural terrain structures. The first factor may, to some extent, be improved by using a higher number of ALS pulses per square meter. The second factor is difficult to change, and also highlights another challenge: how to make a general automatic method that is applicable in all types of terrain within a country. The mixed experience with traditional pattern recognition for semi-automatic mapping of cultural heritage led us to consider deep learning as an alternative approach. The main principle is that a general feature detector has been trained on a large image database. The feature detector is then tailored to a specific task by using a modest number of images of true and false examples of the features being sought. Results of using deep learning are compared with previous results using traditional pattern recognition.

Human Factors Research in Aircrew Performance and Training: 1986-1991

DTIC Science & Technology

1992-07-01

significant loss of realism . Seventeen functions could not be performed at all, primarily because of three missing system features: an automated target...traditionally trained aviators. In 1979, Anacapa developed 13 cinematic exercises to provide supplemental training in map interpretation and terrain

Martian channels and valleys: Their characteristics, distribution, and age

USGS Publications Warehouse

Carr, M.H.; Clow, G.D.

1981-01-01

All Martian channels and valleys visible at a resolution of 125 to 300 meters between 65??N and 65??S were mapped at a scale of 1:5,000,000 and the maps then digitized. Correlations of valley presence with other surface features show that almost all valleys are in the old cratered terrain. preferentially in areas of low albedo, low violet/red ratios, and high elevation. The networks are open, the individual drainage basins are small relative to Earth, and large distances separate the basins, features which all suggest an immature drainage system. The simplest explanation of the correlations and the restriction of valley networks to old terrain is that the channels themselves are old, and that the climatic conditions necessary for their formation did not prevail for long after the decline in the cratering rate around 3.9 billion years ago. Two types of outflow channel are distinguished: unconfined, in which broad swaths of terrain are scoured, and confined, in which flow is restricted to discrete channels. The outflow channels have a wide range of ages and may form under present climatic conditions. Fretted channels are largely restrited to two latitude belts centered on 40??N and 45??S, where relatively rapid erosion along escarpments results from mass wasting. They probably form by enlargement of preexisting channels by escarpment retreat. ?? 1981.

Spatial Coverage Planning for Exploration Robots

NASA Technical Reports Server (NTRS)

Gaines, Daniel; Estlin, Tara; Chouinard, Caroline

2007-01-01

A report discusses an algorithm for an onboard planning and execution technology to support the exploration and characterization of geological features by autonomous rovers. A rover that is capable of deciding which observations are more important relieves the engineering team from much of the burden of attempting to make accurate predictions of what the available rover resources will be in the future. Instead, the science and engineering teams can uplink a set of observation requests that may potentially oversubscribe resources and let the rover use observation priorities and its current assessment of available resources to make decisions about which observations to perform and when to perform them. The algorithm gives the rover the ability to model spatial coverage quality based on data from different scientific instruments, to assess the impact of terrain on coverage quality, to incorporate user-defined priorities among subregions of the terrain to be covered, and to update coverage quality rankings of observations when terrain knowledge changes. When the rover is exploring large geographical features such as craters, channels, or boundaries between two different regions, an important factor in assessing the quality of a mission plan is how the set of chosen observations spatially cover the area of interest. The algorithm allows the rover to evaluate which observation to perform and to what extent the candidate observation will increase the spatial coverage of the plan.

Evaluation of Lightning Jumps as a Predictor of Severe Weather in the Northeastern United States

NASA Astrophysics Data System (ADS)

Eck, Pamela

Severe weather events in the northeastern United States can be challenging to forecast, given how the evolution of deep convection can be influenced by complex terrain and the lack of quality observations in complex terrain. To supplement existing observations, this study explores using lightning to forecast severe convection in areas of complex terrain in the northeastern United States. A sudden increase in lightning flash rate by two standard deviations (2sigma), also known as a lightning jump, may be indicative of a strengthening updraft and an increased probability of severe weather. This study assesses the value of using lightning jumps to forecast severe weather during July 2015 in the northeastern United States. Total lightning data from the National Lightning Detection Network (NLDN) is used to calculate lightning jumps using a 2sigma lightning jump algorithm with a minimum threshold of 5 flashes min-1. Lightning jumps are used to predict the occurrence of severe weather, as given by whether a Storm Prediction Center (SPC) severe weather report occurred 45 min after a lightning jump in the same cell. Results indicate a high probability of detection (POD; 85%) and a high false alarm rate (FAR; 89%), suggesting that lightning jumps occur in sub-severe storms. The interaction between convection and complex terrain results in a locally enhanced updraft and an increased probability of severe weather. Thus, it is hypothesized that conditioning on an upslope variable may reduce the FAR. A random forest is introduced to objectively combine upslope flow, calculated using data from the High Resolution Rapid Refresh (HRRR), flash rate (FR), and flash rate changes with time (DFRDT). The random forest, a machine-learning algorithm, uses pattern recognition to predict a severe or non-severe classification based on the predictors. In addition to upslope flow, FR, and DFRDT, Next-Generation Radar (NEXRAD) Level III radar data was also included as a predictor to compare its value to that of lightning data. Results indicate a high POD (82%), a low FAR (28%), and that lightning data and upslope flow data account for 39% and 32% of variable importance, respectively.

CFD Study of the Performance of an Operational Wind Farm and its Impact on the Local Climate: CFD sensitivity to forestry modelling

NASA Astrophysics Data System (ADS)

Wylie, Scott; Watson, Simon

2013-04-01

Any past, current or projected future wind farm developments are highly dependent on localised climatic conditions. For example the mean wind speed, one of the main factors in assessing the economic feasibility of a wind farm, can vary significantly over length scales no greater than the size of a typical wind farm. Any additional heterogeneity at a potential site, such as forestry, can affect the wind resource further not accounting for the additional difficulty of installation. If a wind farm is sited in an environmentally sensitive area then the ability to predict the wind farm performance and possible impacts on the important localised climatic conditions are of increased importance. Siting of wind farms in environmentally sensitive areas is not uncommon, such as areas of peat-land as in this example. Areas of peat-land are important sinks for carbon in the atmosphere but their ability to sequester carbon is highly dependent on the local climatic conditions. An operational wind farm's impact on such an area was investigated using CFD. Validation of the model outputs were carried out using field measurements from three automatic weather stations (AWS) located throughout the site. The study focuses on validation of both wind speed and turbulence measurement, whilst also assessing the models ability to predict wind farm performance. The use of CFD to model the variation in wind speed over heterogeneous terrain, including wind turbines effects, is increasing in popularity. Encouraging results have increased confidence in the ability of CFD performance in complex terrain with features such as steep slopes and forests, which are not well modelled by the widely used linear models such as WAsP and MS-Micro. Using concurrent measurements from three stationary AWS across the wind farm will allow detailed validation of the model predicted flow characteristics, whilst aggregated power output information will allow an assessment of how accurate the model setup can predict wind farm performance. Given the dependence of the local climatic conditions influence on the peat-land's ability to sequester carbon, accurate predictions of the local wind and turbulence features will allow us to quantify any possible wind farm influences. This work was carried out using the commercially available Reynolds Averaged Navier-Stokes (RANS) CFD package ANSYS CFX. Utilising the Windmodeller add-on in CFX, a series of simulations were carried out to assess wind flow interactions through and around the wind farm, incorporating features such as terrain, forestry and rotor wake interactions. Particular attention was paid to forestry effects, as the AWS are located close to the vicinity of forestry. Different Leaf Area Densities (LAD) were tested to assess how sensitive the models output was to this change.

Fortuna Tessera, Venus - Evidence of horizontal convergence and crustal thickening

NASA Technical Reports Server (NTRS)

Vorder Bruegge, R. W.; Head, J. W.

1989-01-01

Structural and tectonic patterns mapped in Fortuna Tessera are interpreted to reflect a change in the style and intensity of deformation from east to west, beginning with simple tessera terrain at relatively low topographic elevations in the east and progressing through increasingly complex deformation patterns and higher topography to Maxwell Montes in the West. These morphologic and topographic patterns are consistent with east-to-west convergence and compression and the increasing elevations are interpreted to be due to crustal thickening processes associated with the convergent deformational environment. Using an Airy isostatic model, crustal thicknesses of approximately 35 km for the initial tessera terrain, and crustal thicknesses of over 100 km for the Maxwell Montes region are predicted. Detailed mapping with Magellan data will permit the deconvolution of individual components and structures in this terrain.

WRF Model Simulations of Terrain-Driven Atmospheric Eddies in Marine Stratocumulus Clouds

NASA Astrophysics Data System (ADS)

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

2014-12-01

It is not unusual to observe atmospheric eddies in satellite imagery of the marine stratus and stratocumulus clouds that characterize the summertime weather of the California coastal region and near-shore oceanic environment. The winds of the marine atmospheric boundary layer (MABL) over the ocean interact with the high terrain of prominent headlands and islands to create order-10 km scale areas of swirling air that can contain a cloud-free eye, 180-degree wind reversals at the surface over a period of minutes, and may be associated with mixing and turbulence between the high-humidity air of the MABL and the much warmer and drier inversion layer air above. However, synoptic and even subsynoptic surface weather measurements, and the synoptic upper-air observing network are inadequate, or in some cases, completely unable, to detect and characterize the formation, movement, and even the existence of the eddies. They can literally slip between land-based surface observation locations, or stay over the near-shore ocean environment where there may be no surface meteorological measurements. This study presents Weather Research and Forecasting (WRF) Model simulations of these small-scale, terrain-driven, atmospheric features in the MABL from cases detected in GOES satellite imagery. The purpose is to use model output to diagnose the formation mechanisms, sources of vorticity, and the air flow in and around the eddies. Satellite imagery is compared to simulated atmospheric variables to validate features generated within the model atmosphere, and model output is employed as a surrogate atmosphere to better understand the atmospheric characteristics of the eddies. Model air parcel trajectories are estimated to trace the movement and sources of the air contained in and around these often-observed, but seldom-measured features.

Comparison of new generation low-complexity flood inundation mapping tools with a hydrodynamic model

NASA Astrophysics Data System (ADS)

Afshari, Shahab; Tavakoly, Ahmad A.; Rajib, Mohammad Adnan; Zheng, Xing; Follum, Michael L.; Omranian, Ehsan; Fekete, Balázs M.

2018-01-01

The objective of this study is to compare two new generation low-complexity tools, AutoRoute and Height Above the Nearest Drainage (HAND), with a two-dimensional hydrodynamic model (Hydrologic Engineering Center-River Analysis System, HEC-RAS 2D). The assessment was conducted on two hydrologically different and geographically distant test-cases in the United States, including the 16,900 km2 Cedar River (CR) watershed in Iowa and a 62 km2 domain along the Black Warrior River (BWR) in Alabama. For BWR, twelve different configurations were set up for each of the models, including four different terrain setups (e.g. with and without channel bathymetry and a levee), and three flooding conditions representing moderate to extreme hazards at 10-, 100-, and 500-year return periods. For the CR watershed, models were compared with a simplistic terrain setup (without bathymetry and any form of hydraulic controls) and one flooding condition (100-year return period). Input streamflow forcing data representing these hypothetical events were constructed by applying a new fusion approach on National Water Model outputs. Simulated inundation extent and depth from AutoRoute, HAND, and HEC-RAS 2D were compared with one another and with the corresponding FEMA reference estimates. Irrespective of the configurations, the low-complexity models were able to produce inundation extents similar to HEC-RAS 2D, with AutoRoute showing slightly higher accuracy than the HAND model. Among four terrain setups, the one including both levee and channel bathymetry showed lowest fitness score on the spatial agreement of inundation extent, due to the weak physical representation of low-complexity models compared to a hydrodynamic model. For inundation depth, the low-complexity models showed an overestimating tendency, especially in the deeper segments of the channel. Based on such reasonably good prediction skills, low-complexity flood models can be considered as a suitable alternative for fast predictions in large-scale hyper-resolution operational frameworks, without completely overriding hydrodynamic models' efficacy.

Solution of the problem of superposing image and digital map for detection of new objects

NASA Astrophysics Data System (ADS)

Rizaev, I. S.; Miftakhutdinov, D. I.; Takhavova, E. G.

2018-01-01

The problem of superposing the map of the terrain with the image of the terrain is considered. The image of the terrain may be represented in different frequency bands. Further analysis of the results of collation the digital map with the image of the appropriate terrain is described. Also the approach to detection of differences between information represented on the digital map and information of the image of the appropriate area is offered. The algorithm for calculating the values of brightness of the converted image area on the original picture is offered. The calculation is based on using information about the navigation parameters and information according to arranged bench marks. For solving the posed problem the experiments were performed. The results of the experiments are shown in this paper. The presented algorithms are applicable to the ground complex of remote sensing data to assess differences between resulting images and accurate geopositional data. They are also suitable for detecting new objects in the image, based on the analysis of the matching the digital map and the image of corresponding locality.

Scrambled Ice

NASA Technical Reports Server (NTRS)

1998-01-01

This complex area on the side of Europa which faces away from Jupiter shows several types of features which are formed by disruptions of Europa's icy crust. North is to the top of the image, taken by NASA's Galileo spacecraft, and the Sun illuminates the surface from the left. The prominent wide, dark bands are up to 20 kilometers (12 miles) wide and over 50 kilometers (30 miles) long. They are believed to have formed when Europa's icy crust fractured, separated and filled in with darker, 'dirtier' ice or slush from below. A relatively rare type of feature on Europa is the 15-kilometer-diameter (9.3-mile) impact crater in the lower left corner. The small number of impact craters on Europa's surface is an indication of its relatively young age. A region of chaotic terrain south of this impact crater contains crustal plates which have broken apart and rafted into new positions. Some of these 'ice rafts' are nearly 1 kilometer (about half a mile) across. Other regions of chaotic terrain are visible and indicate heating and disruption of Europa's icy crust from below. The youngest features in this scene are the long, narrow cracks in the ice which cut across all other features. One of these cracks is about 30 kilometers (18 miles) to the right of the impact crater and extends for hundreds of miles from the top to the bottom of the image.

The image, centered near 23 degrees south latitude and 179 degrees longitude, covers an area about 240 by 215 kilometers (150 by 130 miles) across. The finest details that can be discerned in this picture are about 460 meters (500 yards) across. The image was taken as Galileo flew by Europa on March 29, 1998. The image was taken by the onboard solid state imaging system camera from an altitude of 23,000 kilometers (14,000 miles).

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

ARC-1989-A89-7025

NASA Image and Video Library

1989-08-24

P-34687 Range : 530,000 km. ( 330,000 miles ) Smallest Resolvable Feature : 10 km or 6 miles This Voyager 2 image of Neptune's satellite Triton shows the first photo of Triton to reveal surface topography. The south pole, continuously illuminated by sunlight at this season, ia at bottom left. the boundary between bright southern hemisphere and the darker and the darker, northern hemisphere is clearly visible. Both the darker regions to the north and the very bright sub-equatorial band show a complex pattern of irregular topography that somewhat resembles 'fretted terrain' on parts of Venus and Mars. The pattern of dark and light regions over most of the southern hemisphere will require higher resolution images for interpretation. Also evident are long, straight lines that appear to be surface expressions of internal, tectonic processes. No large impact ctaters are visible, suggesting that the crust of Triton has been renewed relatively recently, that is, within the last bllion years or less.

Inventory and monitoring of natural vegetation and related resources in an arid environment: A comprehensive evaluation of ERTS-1 imagery. [Arizona

NASA Technical Reports Server (NTRS)

Schrumpf, B. J. (Principal Investigator); Johnson, J. R.; Mouat, D. A.; Pyott, W. T.

1974-01-01

The author has identified the following significant results. A vegetation classification, with 31 types and compatible with remote sensing applications, was developed for the test site. Terrain features can be used to discriminate vegetation types. Elevation and macrorelief interpretations were successful on ERTS photos, although for macrorelief, high sun angle stereoscopic interpretations were better than low sun angle monoscopic interpretations. Using spectral reflectivity, several vegetation types were characterized in terms of patterns of signature change. ERTS MSS digital data were used to discriminate vegetation classes at the association level and at the alliance level when image contrasts were high or low, respectively. An imagery comparison technique was developed to test image complexity and image groupability. In two stage sampling of vegetation types, ERTS plus high altitude photos were highly satisfactory for estimating kind and extent of types present, and for providing a mapping base.

Europa: Initial Galileo Geological Observations

USGS Publications Warehouse

Greeley, R.; Sullivan, R.; Klemaszewski, J.; Homan, K.; Head, J. W.; Pappalardo, R.T.; Veverka, J.; Clark, B.E.; Johnson, T.V.; Klaasen, K.P.; Belton, M.; Moore, J.; Asphaug, E.; Carr, M.H.; Neukum, G.; Denk, T.; Chapman, C.R.; Pilcher, C.B.; Geissler, P.E.; Greenberg, R.; Tufts, R.

1998-01-01

Images of Europa from the Galileo spacecraft show a surface with a complex history involving tectonic deformation, impact cratering, and possible emplacement of ice-rich materials and perhaps liquids on the surface. Differences in impact crater distributions suggest that some areas have been resurfaced more recently than others; Europa could experience current cryovolcanic and tectonic activity. Global-scale patterns of tectonic features suggest deformation resulting from non-synchronous rotation of Europa around Jupiter. Some regions of the lithosphere have been fractured, with icy plates separated and rotated into new positions. The dimensions of these plates suggest that the depth to liquid or mobile ice was only a few kilometers at the time of disruption. Some surfaces have also been upwarped, possibly by diapirs, cryomagmatic intrusions, or convective upwelling. In some places, this deformation has led to the development of chaotic terrain in which surface material has collapsed and/or been eroded. ?? 1998 Academic Press.

The galilean satellites and Jupiter: Voyager 2 imaging science results

USGS Publications Warehouse

Smith, B.A.; Soderblom, L.A.; Beebe, R.; Boyce, J.; Briggs, G.; Carr, M.; Collins, S.A.; Cook, A.F.; Danielson, G.E.; Davies, M.E.; Hunt, G.E.; Ingersoll, A.; Johnson, T.V.; Masursky, H.; McCauley, J.; Morrison, D.; Owen, Timothy W.; Sagan, C.; Shoemaker, E.M.; Strom, R.; Suomi, V.E.; Veverka, J.

1979-01-01

Voyager 2, during its encounter with the Jupiter system, provided images that both complement and supplement in important ways the Voyager 1 images. While many changes have been observed in Jupiter's visual appearance, few, yet significant, changes have been detected in the principal atmospheric currents. Jupiter's ring system is strongly forward scattering at visual wavelengths and consists of a narrow annulus of highest particle density, within which is a broader region in which the density is lower. On Io, changes are observed in eruptive activity, plume structure, and surface albedo patterns. Europa's surface retains little or no record of intense meteorite bombardment, but does reveal a complex and, as yet, little-understood system of overlapping bright and dark linear features. Ganymede is found to have at least one unit of heavily cratered terrain on a surface that otherwise suggests widespread tectonism. Except for two large ringed basins, Callisto's entire surface is heavily cratered. Copyright ?? 1979 AAAS.

Pattern, age, and origin of structural features within the Ozark plateau and the relationship to ore deposits

NASA Technical Reports Server (NTRS)

Arvidson, R. E.

1981-01-01

Topography and gravity anomaly images for the continental United States were constructed. Evidence was found based on gravity, remote sensing data, the presence, trend, and character of fractures, and on rock type data, for a Precambrian rift through Missouri. The feature is probably the failed arm of a triple junction that existed prior to formation of the granite-rhyolite terrain of southern Missouri.

Irregular-Mesh Terrain Analysis and Incident Solar Radiation for Continuous Hydrologic Modeling in Mountain Watersheds

NASA Astrophysics Data System (ADS)

Moreno, H. A.; Ogden, F. L.; Alvarez, L. V.

2016-12-01

This research work presents a methodology for estimating terrain slope degree, aspect (slope orientation) and total incoming solar radiation from Triangular Irregular Network (TIN) terrain models. The algorithm accounts for self shading and cast shadows, sky view fractions for diffuse radiation, remote albedo and atmospheric backscattering, by using a vectorial approach within a topocentric coordinate system and establishing geometric relations between groups of TIN elements and the sun position. A normal vector to the surface of each TIN element describes slope and aspect while spherical trigonometry allows computingunit vector defining the position of the sun at each hour and day of the year. Thus, a dot product determines the radiation flux at each TIN element. Cast shadows are computed by scanning the projection of groups of TIN elements in the direction of the closest perpendicular plane to the sun vector only in the visible horizon range. Sky view fractions are computed by a simplified scanning algorithm from the highest to the lowest triangles along prescribed directions and visible distances, useful to determine diffuse radiation. Finally, remotealbedo is computed from the sky view fraction complementary functions for prescribed albedo values of the surrounding terrain only for significant angles above the horizon. The sensitivity of the different radiative components is tested a in a moutainuous watershed in Wyoming, to seasonal changes in weather and surrounding albedo (snow). This methodology represents an improvement on the current algorithms to compute terrain and radiation values on triangular-based models in an accurate and efficient manner. All terrain-related features (e.g. slope, aspect, sky view fraction) can be pre-computed and stored for easy access for a subsequent, progressive-in-time, numerical simulation.

Understanding the Geographic Controls of Hazardous Convective Weather Environments in the United States

NASA Astrophysics Data System (ADS)

Reed, K. A.; Chavas, D. R.

2017-12-01

Hazardous Convective Weather (HCW), such as severe thunderstorms and tornadoes, poses significant risk to life and property in the United States every year. While these HCW events are small scale, they develop principally within favorable larger-scale environments (i.e., HCW environments). Why these large-scale environments are confined to specific regions, particularly the Eastern United States, is not well understood. This can, in part, be related to a limited fundamental knowledge of how the climate system creates HCW environment, which provides uncertainty in how HCW environments may be altered in a changing climate. Previous research has identified the Gulf of Mexico to the south and elevated terrain upstream as key geographic contributors to the generation of HCW environments over the Eastern United States. This work investigates the relative role of these geographic features through "component denial" experiments in the Community Atmosphere Model version 5 (CAM5). In particular, CAM5 simulations where topography is removed (globally and regionally) and/or the Gulf of Mexico is converted to land is compared to a CAM5 control simulation of current climate following the Atmospheric Model Intercomparison Project (AMIP) protocols. In addition to exploring differences in general characteristics of the large-scale environments amongst the experiments, HCW changes will be explored through a combination of high shear and high Convective Available Potential Energy (CAPE) environments. Preliminary work suggests that the removal of elevated terrain reduces the inland extent of HCW environments in the United States, but not the existence of these events altogether. This indicates that topography is crucial for inland HCW environments but perhaps not for their existence in general (e.g., near the Gulf of Mexico). This initial work is a crucial first step to building a reduced-complexity framework within CAM5 to quantify how land-ocean contrast and elevated terrain control HCW environments.

Self Consistent Bathymetric Mapping Using Sub-maps: Survey Results From the TAG Hydrothermal Structure

NASA Astrophysics Data System (ADS)

Roman, C. N.; Reves-Sohn, R.; Singh, H.; Humphris, S.

2005-12-01

The spatial resolution of microbathymetry maps created using robotic vehicles such as ROVs, AUVs and manned submersibles in the deep ocean is currently limited by the accuracy of the vehicle navigation data. Errors in the vehicle position estimate commonly exceed the ranging errors of the acoustic mapping sensor itself, which creates inconsistency in the map making process and produces artifacts that lower resolution and distort map integrity. We present a methodology for producing self-consistent maps and improving vehicle position estimation by exploiting accurate local navigation and utilizing terrain relative measurements. The complete map is broken down into individual "sub-maps'', which are generated using short term Doppler based navigation. The sub-maps are pairwise registered to constrain the vehicle position estimates by matching terrain that has been imaged multiple times. This procedure is implemented using a delayed state Kalman filter to incorporate the sub-map registrations as relative position measurements between previously visited vehicle locations. Archiving of previous positions in a filter state vector allows for continual adjustment of the sub-map locations. The terrain registration is accomplished using a two dimensional correlation and a six degree of freedom point cloud alignment method tailored to bathymetric data. This registration procedure is applicable to fully 3 dimensional complex underwater environments. The complete bathymetric map is then created from the union of all sub-maps that have been aligned in a consistent manner. The method is applied to an SM2000 multibeam survey of the TAG hydrothermal structure on the Mid-Atlantic Ridge at 26(°)N using the Jason II ROV. The survey included numerous crossing tracklines designed to test this algorithm, and the final gridded bathymetry data is sub-meter accurate. The high-resolution map has allowed for the identification of previously unrecognized fracture patterns associated with flow focusing at TAG, as well as imaging of fine-scale features such as individual sulfide talus blocks and ODP re-entry cones.

How to Make a Virtual Landscape with Outcrops for Use in Geoscience Teaching

NASA Astrophysics Data System (ADS)

Houghton, J.; Gordon, C.; Craven, B.; Robinson, A.; Lloyd, G. E. E.; Morgan, D. J.

2016-12-01

We are using screen-based virtual reality landscapes to augment the teaching of basic geological field skills and to enhance 3D visualisation skills. Here we focus on the processes of creating these landscapes, both imagined and real, in the Unity 3D game engine. The virtual landscapes are terrains with embedded data for mapping exercises, or draped geological maps for understanding the 3D interaction of the geology with the topography. The nature of the landscapes built depends on the learning outcomes of the intended teaching exercise. For example, a simple model of two hills and a valley over which to drape a series of different geological maps can be used to enhance the understanding of the 3D interaction of the geology with the topography. A more complex topography reflecting the underlying geology can be used for geological mapping exercises. The process starts with a contour image or DEM, which needs to be converted into RAW files to be imported into Unity. Within Unity itself, there are a series of steps needed to create a world around the terrain (the setting of cameras, lighting, skyboxes etc) before the terrain can be painted with vegetation and populated with assets or before a splatmap of the geology can be added. We discuss how additional features such as a GPS unit or compass can be included. We are also working to create landscapes based on real localities, both in response to the demand for greater realism and to support students unable to access the field due to health or mobility issues. This includes adding 3D photogrammetric images of outcrops into the worlds. This process uses the open source/freeware tools VisualSFM and MeshLab to create files suitable to be imported into Unity. This project is a collaboration between the University of Leeds and Leeds College of Art, UK, and all our virtual landscapes are freely available online at www.see.leeds.ac.uk/virtual-landscapes/.

Groundwater potential index in a crystalline terrain using remote sensing data

NASA Astrophysics Data System (ADS)

Subba Rao, N.

2006-08-01

Demand for groundwater for drinking, agricultural and industrial purposes has increased due to uncertainty in the surface water supply. Agriculture is the main occupation of the rural people in Guntur district, Andhra Pradesh, India. Development of groundwater in the district is very less, indicating a lot of scope for further development of groundwater resources. However, assessment of groundwater conditions, particularly in a crystalline terrain, is a complex task because of variations in weathering and fracturing zones from place to place. Systematic studies for evaluation of groundwater potential zones have been carried out in a crystalline terrain of the district. Information on soils, geological formations and groundwater conditions is collected during the hydrogeological survey. Topographical and drainage conditions are derived from the Survey of India topographical maps. Geomorphological units and associated landform features inferred and delineated from the Indian remote sensing satellite imagery (IRS ID LISS III FCC) are moderately buried pediplain (BPM), shallow buried pediplain (BPS), valley fills (VF), structural hill (SH), residual hills (RH), lineaments and land use/land cover. A groundwater potential index (GPI) is computed for relative evaluation of groundwater potential zones in the study area by integrating all the related factors of occurrence and movement of groundwater resources. Accordingly, the landforms, BPM, BPS, VF, SH and RH, of the area are categorized as very good groundwater potential zone, good to moderate groundwater potential zone, moderate to poor groundwater potential zone, poor to very poor groundwater potential zone and very poor groundwater potential zone, respectively, for development and utilization of both groundwater and surface water resources for eliminating water scarcity. This study could help to improve the agrarian economy for better living conditions of the rural people. Taking the total weight-score of the GPI into account, a generalized classification of groundwater potential zones is evaluated for a quick assessment of the occurrence of groundwater resources on regional scale.

Extensional terrain formation on Europa and Ganymede: Implications for ocean-surface interaction

NASA Astrophysics Data System (ADS)

Howell, S. M.; Pappalardo, R. T.

2017-12-01

Europa and Ganymede, Galilean satellites of Jupiter, exhibit geologic activity in their outer H2O ice shells that might convey material from water oceans within the satellites to their surfaces. Imagery from the Voyager and Galileo spacecraft reveal surfaces rich with tectonic deformation, including dilational bands on Europa and groove lanes on Ganymede. These features are generally attributed to the extension of a brittle ice lithosphere overlaying a possibly convecting ice asthenosphere. To explore band formation and interaction with interior oceans, we employ fully visco-elasto-plastic 2-D models of faulting and convection with complex, realistic pure ice rheologies. In these models, material entering from below is tracked and considered to be "fossilized ocean," ocean material that has frozen into the ice shell and evolves through geologic time. We track the volume fraction of fossil ocean material in the ice shell as a function of depth, and the exposure of both fresh ice and fossil ocean material at the ice shell surface. We vary ice shell thickness, fault localization, melting-temperature ice viscosity, and the presence of pre-existing weaknesses. Mechanisms which act to weaken the ice shell and thin the lithosphere (e.g. vigorous convection, thinner shells, pre-existing weaknesses) tend to plastically yield to form smooth bands at high strains, and are more likely to incorporate fossil ocean material in the ice shell and expose it at the surface. In contrast, lithosphere strengthened by rapid fault annealing or increased viscosity, for example, exhibits large-scale tectonic rifting at low strains superimposed over pre-existing terrains, and inhibits the incorporation and delivery of fossil ocean material to the surface. Thus, our results identify a spectrum of extensional terrain formation mechanisms as linked to lithospheric strength, rather than any specific mechanism being unique to each type of band, and where in this spectrum ocean material incorporated at the bottom of the ice shell may be exposed on the satellite surface.

A framework for global terrain classification using 250-m DEMs to predict geohazards

NASA Astrophysics Data System (ADS)

Iwahashi, J.; Matsuoka, M.; Yong, A.

2016-12-01

Geomorphology is key for identifying factors that control geohazards induced by landslides, liquefaction, and ground shaking. To systematically identify landforms that affect these hazards, Iwahashi and Pike (2007; IP07) introduced an automated terrain classification scheme using 1-km-scale Shuttle Radar Topography Mission (SRTM) digital elevation models (DEMs). The IP07 classes describe 16 categories of terrain types and were used as a proxy for predicting ground motion amplification (Yong et al., 2012; Seyhan et al., 2014; Stewart et al., 2014; Yong, 2016). These classes, however, were not sufficiently resolved because coarse-scaled SRTM DEMs were the basis for the categories (Yong, 2016). Thus, we develop a new framework consisting of more detailed polygonal global terrain classes to improve estimations of soil-type and material stiffness. We first prepare high resolution 250-m DEMs derived from the 2010 Global Multi-resolution Terrain Elevation Data (GMTED2010). As in IP07, we calculate three geometric signatures (slope, local convexity and surface texture) from the DEMs. We create additional polygons by using the same signatures and multi-resolution segmentation techniques on the GMTED2010. We consider two types of surface texture thresholds in different window sizes (3x3 and 13x13 pixels), in addition to slope and local convexity, to classify pixels within the DEM. Finally, we apply the k-means clustering and thresholding methods to the 250-m DEM and produce more detailed polygonal terrain classes. We compare the new terrain classification maps of Japan and California with geologic, aerial photography, and landslide distribution maps, and visually find good correspondence of key features. To predict ground motion amplification, we apply the Yong (2016) method for estimating VS30. The systematic classification of geomorphology has the potential to provide a better understanding of the susceptibility to geohazards, which is especially vital in populated areas.

Evaluation of low wind modeling approaches for two tall-stack databases.

PubMed

Paine, Robert; Samani, Olga; Kaplan, Mary; Knipping, Eladio; Kumar, Naresh

2015-11-01

The performance of the AERMOD air dispersion model under low wind speed conditions, especially for applications with only one level of meteorological data and no direct turbulence measurements or vertical temperature gradient observations, is the focus of this study. The analysis documented in this paper addresses evaluations for low wind conditions involving tall stack releases for which multiple years of concurrent emissions, meteorological data, and monitoring data are available. AERMOD was tested on two field-study databases involving several SO2 monitors and hourly emissions data that had sub-hourly meteorological data (e.g., 10-min averages) available using several technical options: default mode, with various low wind speed beta options, and using the available sub-hourly meteorological data. These field study databases included (1) Mercer County, a North Dakota database featuring five SO2 monitors within 10 km of the Dakota Gasification Company's plant and the Antelope Valley Station power plant in an area of both flat and elevated terrain, and (2) a flat-terrain setting database with four SO2 monitors within 6 km of the Gibson Generating Station in southwest Indiana. Both sites featured regionally representative 10-m meteorological databases, with no significant terrain obstacles between the meteorological site and the emission sources. The low wind beta options show improvement in model performance helping to reduce some of the over-prediction biases currently present in AERMOD when run with regulatory default options. The overall findings with the low wind speed testing on these tall stack field-study databases indicate that AERMOD low wind speed options have a minor effect for flat terrain locations, but can have a significant effect for elevated terrain locations. The performance of AERMOD using low wind speed options leads to improved consistency of meteorological conditions associated with the highest observed and predicted concentration events. The available sub-hourly modeling results using the Sub-Hourly AERMOD Run Procedure (SHARP) are relatively unbiased and show that this alternative approach should be seriously considered to address situations dominated by low-wind meander conditions. AERMOD was evaluated with two tall stack databases (in North Dakota and Indiana) in areas of both flat and elevated terrain. AERMOD cases included the regulatory default mode, low wind speed beta options, and use of the Sub-Hourly AERMOD Run Procedure (SHARP). The low wind beta options show improvement in model performance (especially in higher terrain areas), helping to reduce some of the over-prediction biases currently present in regulatory default AERMOD. The SHARP results are relatively unbiased and show that this approach should be seriously considered to address situations dominated by low-wind meander conditions.

OIL SPILL RESPONSE SCENARIOS FOR REMOTE ARCTIC ENVIRONMENTS

EPA Science Inventory

Special problems occur during oil spill cleanup in remote inland areas in cold climates. In Alaska these problems result from the harsh climate, the unusual terrain features, and the special problems of spills along swift rivers. The analysis begins with a description of the envi...

Comet Borrelly's Varied Landscape

NASA Technical Reports Server (NTRS)

2001-01-01

In this Deep Space 1 image of comet Borrelly, sunlight illuminates the bowling-pin shaped nucleus from directly below. At this distance, many features are become vivid on the surface of the nucleus, including a jagged line between day and night on the comet, rugged terrain on both ends with dark patches, and smooth, brighter terrain near the center. The smallest discernable features are about 110 meters (120 yards) across.

Deep Space 1 completed its primary mission testing ion propulsion and 11 other advanced, high-risk technologies in September 1999. NASA extended the mission, taking advantage of the ion propulsion and other systems to undertake this chancy but exciting, and ultimately successful, encounter with the comet. More information can be found on the Deep Space 1 home page at http://nmp.jpl.nasa.gov/ds1/ .

Deep Space 1 was launched in October 1998 as part of NASA's New Millennium Program, which is managed by JPL for NASA's Office of Space Science, Washington, D.C. The California Institute of Technology manages JPL for NASA.

Hyperspectral landcover classification for the Yakima Training Center, Yakima, Washington

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steinmaus, K.L.; Perry, E.M.; Petrie, G.M.

1998-04-01

The US Department of Energy`s (DOE`s) Pacific Northwest National Laboratory (PNNL) was tasked in FY97-98 to conduct a multisensor feature extraction project for the Terrain Modeling Project Office (TMPO) of the National Imagery and Mapping Agency (NIMA). The goal of this research is the development of near-autonomous methods to remotely classify and characterize regions of military interest, in support of the TMPO of NIMA. These methods exploit remotely sensed datasets including hyperspectral (HYDICE) imagery, near-infrared and thermal infrared (Daedalus 3600), radar, and terrain datasets. The study site for this project is the US Army`s Yakima Training Center (YTC), a 326,741-acremore » training area located near Yakima, Washington. Two study areas at the YTC were selected to conduct and demonstrate multisensor feature extraction, the 2-km x 2-km Cantonment Area and the 3-km x 3-km Choke Point area. Classification of the Cantonment area afforded a comparison of classification results at different scales.« less

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.

Airborne lidar-based estimates of tropical forest structure in complex terrain: opportunities and trade-offs for REDD+

PubMed

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

2015-12-01

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. 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 (~20 returns m -2 ) data was highly accurate (mean signed error of 0.19 ± 0.97 m), while those derived from reduced-density datasets (8 m -2 , 4 m -2 , 2 m -2 and 1 m -2 ) 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 m -2 , the bias in height estimates translated into errors of 80-125 Mg ha -1 in predicted aboveground biomass. 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.

Mini-Uav LIDAR for Power Line Inspection

NASA Astrophysics Data System (ADS)

Teng, G. E.; Zhou, M.; Li, C. R.; Wu, H. H.; Li, W.; Meng, F. R.; Zhou, C. C.; Ma, L.

2017-09-01

Light detection and ranging (LIDAR) system based on unmanned aerial vehicles (UAVs) recently are in rapid advancement, meanwhile portable and flexible mini-UAV-borne laser scanners have been a hot research field, especially for the complex terrain survey in the mountains and other areas. This study proposes a power line inspection system solution based on mini-UAV-borne LIDAR system-AOEagle, developed by Academy of Opto-Electronics, Chinese Academy of Sciences, which mounted on a Multi-rotor unmanned aerial vehicle for complex terrain survey according to real test. Furthermore, the point cloud data was explored to validate its applicability for power line inspection, in terms of corridor and line laser point clouds; deformation detection of power towers, etc. The feasibility and advantages of AOEagle have been demonstrated by the promising results based on the real-measured data in the field of power line inspection.

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

DOE PAGES

Berryman, E. M.; Barnard, H. R.; Adams, H. R.; ...

2015-02-10

Forest soil respiration is a major carbon (C) flux that is characterized by significant variability in space and time. In this paper, 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 formore » 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. Finally, 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.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berryman, E. M.; Barnard, H. R.; Adams, H. R.

Forest soil respiration is a major carbon (C) flux that is characterized by significant variability in space and time. In this paper, 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 formore » 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. Finally, 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.« less

Visual control of foot placement when walking over complex terrain.

PubMed

Matthis, Jonathan S; Fajen, Brett R

2014-02-01

The aim of this study was to investigate the role of visual information in the control of walking over complex terrain with irregularly spaced obstacles. We developed an experimental paradigm to measure how far along the future path people need to see in order to maintain forward progress and avoid stepping on obstacles. Participants walked over an array of randomly distributed virtual obstacles that were projected onto the floor by an LCD projector while their movements were tracked by a full-body motion capture system. Walking behavior in a full-vision control condition was compared with behavior in a number of other visibility conditions in which obstacles did not appear until they fell within a window of visibility centered on the moving observer. Collisions with obstacles were more frequent and, for some participants, walking speed was slower when the visibility window constrained vision to less than two step lengths ahead. When window sizes were greater than two step lengths, the frequency of collisions and walking speed were weakly affected or unaffected. We conclude that visual information from at least two step lengths ahead is needed to guide foot placement when walking over complex terrain. When placed in the context of recent research on the biomechanics of walking, the findings suggest that two step lengths of visual information may be needed because it allows walkers to exploit the passive mechanical forces inherent to bipedal locomotion, thereby avoiding obstacles while maximizing energetic efficiency. PsycINFO Database Record (c) 2014 APA, all rights reserved.

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.

Numerical simulations of the transport and diffusion during the 1991 Winter Validation Study along the front range in Colorado

NASA Astrophysics Data System (ADS)

Fast, J. D.; Osteen, B. L.

An important aspect of the U.S. Department of Energy's Atmospheric Studies in Complex Terrain (ASCOT) program is the development and evaluation of numerical models that predict transport and diffusion of pollutants in complex terrain. Operational mesoscale modeling of the transport of pollutants in complex terrain will become increasingly practical as computational costs decrease and additional data from high-resolution remote sensing instrumentation networks become available during the 1990s. Four-dimensional data assimilation (4DDA) techniques are receiving a great deal of attention recently not only to improve the initial conditions of mesoscale forecast models, but to create high-quality four-dimensional mesoscale analysis fields that can be used as input to air-quality models. In this study, a four-dimensional data assimilation technique based on Newtonian relaxation is incorporated into the Colorado State University (CSU) Regional Atmospheric Modeling System (RAMS) and evaluated using data taken from one experiment of the 1991 ASCOT field study along the front range of the Rockies in Colorado. The main objective of this study is to compare the observed surface concentrations with those predicted by a Lagrangian particle dispersion model and to demonstrate the effect of data assimilation on the simulated plume. In contrast to previous studies in which the smallest horizontal grid spacing was 10 km (Stauffer and Seaman, 1991) and 8 km (Yamada and Hermi, 1991), data assimilation is applied in this study to domains with a horizontal grid spacing as small as 1 km.

A morphologically preserved multi-resolution TIN surface modeling and visualization method for virtual globes

NASA Astrophysics Data System (ADS)

Zheng, Xianwei; Xiong, Hanjiang; Gong, Jianya; Yue, Linwei

2017-07-01

Virtual globes play an important role in representing three-dimensional models of the Earth. To extend the functioning of a virtual globe beyond that of a "geobrowser", the accuracy of the geospatial data in the processing and representation should be of special concern for the scientific analysis and evaluation. In this study, we propose a method for the processing of large-scale terrain data for virtual globe visualization and analysis. The proposed method aims to construct a morphologically preserved multi-resolution triangulated irregular network (TIN) pyramid for virtual globes to accurately represent the landscape surface and simultaneously satisfy the demands of applications at different scales. By introducing cartographic principles, the TIN model in each layer is controlled with a data quality standard to formulize its level of detail generation. A point-additive algorithm is used to iteratively construct the multi-resolution TIN pyramid. The extracted landscape features are also incorporated to constrain the TIN structure, thus preserving the basic morphological shapes of the terrain surface at different levels. During the iterative construction process, the TIN in each layer is seamlessly partitioned based on a virtual node structure, and tiled with a global quadtree structure. Finally, an adaptive tessellation approach is adopted to eliminate terrain cracks in the real-time out-of-core spherical terrain rendering. The experiments undertaken in this study confirmed that the proposed method performs well in multi-resolution terrain representation, and produces high-quality underlying data that satisfy the demands of scientific analysis and evaluation.

Thermokarst and thaw-related landscape dynamics -- an annotated bibliography with an emphasis on potential effects on habitat and wildlife

USGS Publications Warehouse

Jones, Benjamin M.; Amundson, Courtney L.; Koch, Joshua C.; Grosse, Guido

2013-01-01

Permafrost has warmed throughout much of the Northern Hemisphere since the 1980s, with colder permafrost sites warming more rapidly (Romanovsky and others, 2010; Smith and others, 2010). Warming of the near-surface permafrost may lead to widespread terrain instability in ice-rich permafrost in the Arctic and the Subarctic, and may result in thermokarst development and other thaw-related landscape features (Jorgenson and others, 2006; Gooseff and others, 2009). Thermokarst and other thaw-related landscape features result from varying modes and scales of permafrost thaw, subsidence, and removal of material. An increase in active-layer depth, water accumulation on the soil surface, permafrost degradation and associated retreat of the permafrost table, and changes to lake shores and coastal bluffs act and interact to create thermokarst and other thaw-related landscape features (Shur and Osterkamp, 2007). There is increasing interest in the spatial and temporal dynamics of thermokarst and other thaw-related features from diverse disciplines including landscape ecology, hydrology, engineering, and biogeochemistry. Therefore, there is a need to synthesize and disseminate knowledge on the current state of near-surface permafrost terrain. The term "thermokarst" originated in the Russian literature, and its scientific use has varied substantially over time (Shur and Osterkamp, 2007). The modern definition of thermokarst refers to the process by which characteristic landforms result from the thawing of ice-rich permafrost or the melting of massive ice (van Everdingen, 1998), or, more specifically, the thawing of ice-rich permafrost and (or) melting of massive ice that result in consolidation and deformation of the soil surface and formation of specific forms of relief (Shur, 1988). Jorgenson (2013) identifies 23 distinct thermokarst and other thaw-related features in the Arctic, Subarctic, and Antarctic based primarily on differences in terrain condition, ground-ice volume, and heat and mass transfer processes. Typical Arctic thermokarst landforms include thermokarst lakes, collapsed pingos, sinkholes, and pits. Thermokarst is differentiated from thermal erosion, which refers to the erosion of the land surface by thermal and mechanical processes (Mackay, 1970; van Everdingen, 1998). Typical thermal erosional features include thermo-erosional gullies. Thermal abrasion is further differentiated from thermokarst and thermal erosion by association with the reworking of ocean, river, and lake bluffs (Are, 1988). Typical thermo-abrasion features include erosional niches at the base of bluffs. Thermal denudation is another distinct term that refers to the effect of incoming solar energy on the thaw of frozen slopes and permafrost bodies that subsequently become transported downhill by gravity (Shur and Osterkamp, 2007). Active layer detachment slides and thaw slumps are typical thermal denudation features. Shur and Osterkamp (2007) noted that these various transport processes may occur together with thermokarst or in instances that would not be considered thermokarst. This compilation of references regarding thermokarst and other thaw-related features is focused on the Arctic and the Subarctic. References were drawn from North America as well as Siberia. English-language literature mostly was targeted, with 167 references annotated in version 1.0; however, an additional 28 Russian-language references were taken from Shur and Osterkamp (2007) and are provided at the end of this document. This compilation may be missing key references and inevitably will become outdated soon after publication. We hope that this document, version 1.0, will serve as the foundation for a comprehensive compilation of thermokarst and permafrost-terrain stability references, and that it will be updated continually over the coming years.

Utilization of 3-D Imaging Flash Lidar Technology for Autonomous Safe Landing on Planetary Bodies

NASA Technical Reports Server (NTRS)

Amzajerdian, Farzin; Vanek, Michael; Petway, Larry; Pierrotter, Diego; Busch, George; Bulyshev, Alexander

2010-01-01

NASA considers Flash Lidar a critical technology for enabling autonomous safe landing of future large robotic and crewed vehicles on the surface of the Moon and Mars. Flash Lidar can generate 3-Dimensional images of the terrain to identify hazardous features such as craters, rocks, and steep slopes during the final stages of descent and landing. The onboard flight computer can use the 3-D map of terrain to guide the vehicle to a safe site. The capabilities of Flash Lidar technology were evaluated through a series of static tests using a calibrated target and through dynamic tests aboard a helicopter and a fixed wing aircraft. The aircraft flight tests were performed over Moon-like terrain in the California and Nevada deserts. This paper briefly describes the Flash Lidar static and aircraft flight test results. These test results are analyzed against the landing application requirements to identify the areas of technology improvement. The ongoing technology advancement activities are then explained and their goals are described.

A variable circular-plot method for estimating bird numbers

Treesearch

R. T. Reynolds; J. M. Scott; R. A. Nussbaum

1980-01-01

A bird census method is presented that is designed for tall, structurally complex vegetation types, and rugged terrain. With this method the observer counts all birds seen or heard around a station, and estimates the horizontal distance from the station to each bird. Count periods at stations vary according to the avian community and structural complexity of the...

Geologic Mapping of the V-36 Thetis Regio Quadrangle: 2008 Progress Report

NASA Technical Reports Server (NTRS)

Basilevsky, A. T.; Head, James W.

2008-01-01

As a result of mapping, eleven material stratigraphic units and three structural units have been identified and mapped. The material units include (from older to younger): tessera terrain material (tt), material of densely fractured plains (pdf), material of fractured and ridged plains (pfr), material of shield plains (psh), material of plains with wrinkle ridges (pwr), material of smooth plains of intermediate brightness (psi), material of radardark smooth plains (psd), material of lineated plains (pli) material of lobate plains (plo), material of craters having no radar-dark haloes (c1), and material of craters having clear dark haloes (c2). The morphologies and probably the nature of the material units in the study area are generally similar to those observed in other regions of Venus [2]. The youngest units are lobate plains (plo) which here typically look less lobate than in other areas of the planet. Close to them in age are smooth plains which are indeed smooth and represented by two varieties mentioned above. Lineated plains (pli) are densely fractured in a geometrically regular way. Plains with wrinkle ridges, being morphologically similar to those observed in other regions, here occupy unusually small areas. Shield (psh) plains here are also not abundant. Locally they show wrinkle ridging. Fractured and ridged plains (pfr), which form in other regions, the so called ridge belts, are observed as isolated areas of clusters of ridged plains surrounded by other units. Densely fractured plains (pdf) are present in relatively small areas in association with coronae and corona-like features. Tessera terrain (tt) is dissected by structures oriented in two or more directions. Structures are so densely packed that the morphology (and thus nature) of the precursor terrain is not known. Structural units include tessera transitional terrain (ttt), fracture belts (fb) and rifted terrain (rt). Tessera transitional terrain was first identified and mapped by [4] as areas of fractured and ridged plains (pfr) and densely fractured plains (pdf) deformed by transverse faults that made it formally resemble tessera terrain (tt). The obvious difference between units tt and ttt is the recognizable morphology of precursor terrain of unit ttt. Fracture belts are probably ancient rift zones [3]. Rifted terrain (rt), as in other regions of Venus, is so saturated with faults that according to the recommendation of [1, 5] it should be mapped as a structural unit.

Assessment of the Suitability of High Resolution Numerical Weather Model Outputs for Hydrological Modelling in Mountainous Cold Regions

NASA Astrophysics Data System (ADS)

Rasouli, K.; Pomeroy, J. W.; Hayashi, M.; Fang, X.; Gutmann, E. D.; Li, Y.

2017-12-01

The hydrology of mountainous cold regions has a large spatial variability that is driven both by climate variability and near-surface process variability associated with complex terrain and patterns of vegetation, soils, and hydrogeology. There is a need to downscale large-scale atmospheric circulations towards the fine scales that cold regions hydrological processes operate at to assess their spatial variability in complex terrain and quantify uncertainties by comparison to field observations. In this research, three high resolution numerical weather prediction models, namely, the Intermediate Complexity Atmosphere Research (ICAR), Weather Research and Forecasting (WRF), and Global Environmental Multiscale (GEM) models are used to represent spatial and temporal patterns of atmospheric conditions appropriate for hydrological modelling. An area covering high mountains and foothills of the Canadian Rockies was selected to assess and compare high resolution ICAR (1 km × 1 km), WRF (4 km × 4 km), and GEM (2.5 km × 2.5 km) model outputs with station-based meteorological measurements. ICAR with very low computational cost was run with different initial and boundary conditions and with finer spatial resolution, which allowed an assessment of modelling uncertainty and scaling that was difficult with WRF. Results show that ICAR, when compared with WRF and GEM, performs very well in precipitation and air temperature modelling in the Canadian Rockies, while all three models show a fair performance in simulating wind and humidity fields. Representation of local-scale atmospheric dynamics leading to realistic fields of temperature and precipitation by ICAR, WRF, and GEM makes these models suitable for high resolution cold regions hydrological predictions in complex terrain, which is a key factor in estimating water security in western Canada.

Characterising the Geomorphology of Forested Floodplains Using High Resolution Terrestrial Laser Scanning

NASA Astrophysics Data System (ADS)

Sear, D. A.; Brasington, J.; Darby, S. E.

2007-12-01

Forested floodplain environments represent the undisturbed land cover of most temperate and tropical river systems, but they are under threat from human resource management (Hughes et al., 2005, FLOBAR II Project report). A scientific understanding of forest floodplain processes therefore has relevance to ecosystem conservation and restoration, and the interpretation of pre-historic river and floodplain evolution. Empirical research has highlighted how overbank flows are relatively shallow and strongly modified by floodplain topography and the presence of vegetation and organic debris on the woodland floor [Jeffries et al., 2003, Geomorphology, 51, 61-80; Millington and Sear, 2007, Earth. Surf. Proc. Landforms, 32, doi: 10.1002/esp.1552]. In such instances flow blockage and diversions are common, and there is the possibility of frequent switches from sub-critical to locally super-critical flow. Such conditions also favour turbulence generation, both by wakes and by shear. Consequently, the floodplain terrain (where we take 'terrain' to include the underlying topography, root structures, and organic debris) plays a key role in modulating the processes of erosion and sedimentation that underpin the physical habitat diversity and hydraulic characteristics of complex wooded floodplain surfaces. However, despite the importance of these issues, as yet there are no formal, quantitative, descriptions of the highly complex and spatially diverse micro- and meso-topography that appears to be characteristic of forested floodplain surfaces. To address this gap, we have undertaken detailed surveys on a small floodplain reach within the Highland Water Research Catchment (HWRC: see http://www.geog.soton.ac.uk/research/nfrc/default.asp), which is a UK national reference site for lowland floodplain forest streams. This involved the deployment of a Leica ScanStation terrestrial laser-scanner from 14 setups and ranges of less than 30 m to acquire an extremely high resolution, accurate (185 million xyz observations, with absolute mean registration errors of 2 mm) 3-d point cloud model of the floodplain. These raw data were processed using a combination of Leica CYCLONE and bespoke filtering algorithms to construct a multi-resolution DTM of the forested floodplain at hitherto unprecedented detail (median point density ~4500 pts m-2). A key point is that the extreme precision and point density permit relevant features of the terrain (micro-topography, protruding roots, branches and stems, and surficial debris) that contribute to the floodplain roughness, to be readily and directly be incorporated in the DTM as topographic features. To characterise the morphology of the floodplain surface we have used the DTM to analyse a range of floodplain morphometric indices, in particular focusing on derivative surface roughness metrics (including roughness height) which are relevant in the parameterization of flow resistance. These are analysed at the floodplain scale to show the spatial distribution of roughness, and at a patch scale selected from a simple classification of floodplain surface. The analysis demonstrates spatial variability in roughness metrics at both scales, which have implications for parameterising flow resistance in models of wooded floodplains.

Follow the line: Mysterious bright streaks on Dione and Rhea

NASA Astrophysics Data System (ADS)

Martin, E. S.; Patthoff, D. A.

2017-12-01

Our recent mapping of the wispy terrains of Saturn's moons Dione and Rhea has revealed unique linear features that are generally long (10s-100s km), narrow (1-10 km), brighter than the surrounding terrains, and their detection may be sensitive to lighting geometries. We refer to these features as `linear virgae.' Wherever linear virgae are observed, they appear to crosscut all other structures, suggesting that they are the youngest features on these satellites. Despite their young age and wide distribution, linear virgae on Rhea and Dione have largely been overlooked in the literature. Linear virgae on Dione have previously been identified in Voyager and Cassini Data, but their formation remains an open question. If linear virgae are found to be endogenic, it would suggest that the surfaces of Dione and Rhea have been active recently. Alternatively, if linear virgae are exogenic it would suggest that the surfaces have been modified by a possibly common mechanism. Further work would be necessary to determine both a source of material and the dynamical environment that could produce these features. Here we present detailed morphometric measurements to further constrain whether linear virgae on Rhea and Dione share common origins. We complete an in-depth assessment of the lighting geometries where these features are visible. If linear virgae in the Saturnian system show common morphologies and distributions, a new, recently active, possibly system-wide mechanism may be revealed, thereby improving our understanding of the recent dynamical environment around Saturn.

47 CFR 76.59 - Modification of television markets.

Code of Federal Regulations, 2010 CFR

2010-10-01

... headend locations, terrain features that would affect station reception, mileage between the community and... establishing historic carriage, such as television guide listings. (6) Published audience data for the relevant station showing its average all day audience (i.e., the reported audience averaged over Sunday-Saturday, 7...

Integrating depth functions and hyper-scale terrain analysis for 3D soil organic carbon modeling in agricultural fields at regional scale

NASA Astrophysics Data System (ADS)

Ramirez-Lopez, L.; van Wesemael, B.; Stevens, A.; Doetterl, S.; Van Oost, K.; Behrens, T.; Schmidt, K.

2012-04-01

Soil Organic Carbon (SOC) represents a key component in the global C cycle and has an important influence on the global CO2 fluxes between terrestrial biosphere and atmosphere. In the context of agricultural landscapes, SOC inventories are important since soil management practices have a strong influence on CO2 fluxes and SOC stocks. However, there is lack of accurate and cost-effective methods for producing high spatial resolution of SOC information. In this respect, our work is focused on the development of a three dimensional modeling approach for SOC monitoring in agricultural fields. The study area comprises ~420 km2 and includes 4 of the 5 agro-geological regions of the Grand-Duchy of Luxembourg. The soil dataset consist of 172 profiles (1033 samples) which were not sampled specifically for this study. This dataset is a combination of profile samples collected in previous soil surveys and soil profiles sampled for other research purposes. The proposed strategy comprises two main steps. In the first step the SOC distribution within each profile (vertical distribution) is modeled. Depth functions for are fitted in order to summarize the information content in the profile. By using these functions the SOC can be interpolated at any depth within the profiles. The second step involves the use of contextual terrain (ConMap) features (Behrens et al., 2010). These features are based on the differences in elevation between a given point location in the landscape and its circular neighbourhoods at a given set of different radius. One of the main advantages of this approach is that it allows the integration of several spatial scales (eg. local and regional) for soil spatial analysis. In this work the ConMap features are derived from a digital elevation model of the area and are used as predictors for spatial modeling of the parameters of the depth functions fitted in the previous step. In this poster we present some preliminary results in which we analyze: i. The use of different depth functions, ii. The use of different machine learning approaches for modeling the parameters of the fitted depth functions using the ConMap features and iii. The influence of different spatial scales on the SOC profile distribution variability. Keywords: 3D modeling, Digital soil mapping, Depth functions, Terrain analysis. Reference Behrens, T., K. Schmidt, K., Zhu, A.X. Scholten, T. 2010. The ConMap approach for terrain-based digital soil mapping. European Journal of Soil Science, v. 61, p.133-143.

Line pilot perspectives on complexity of terminal instrument flight procedures

DOT National Transportation Integrated Search

2017-07-25

Instrument flight procedures (IFPs) based on RNAV and RNP offer safety enhancements along with new levels of flexibility to negotiate terrain, airspace, and environmental considerations. However, operational implementation of performance-based IFPs d...

Quantifying the added value of convection-permitting climate simulations in complex terrain: a systematic evaluation of WRF over the Himalayas

NASA Astrophysics Data System (ADS)

Karki, Ramchandra; Hasson, Shabeh ul; Gerlitz, Lars; Schickhoff, Udo; Scholten, Thomas; Böhner, Jürgen

2017-07-01

Mesoscale dynamical refinements of global climate models or atmospheric reanalysis have shown their potential to resolve intricate atmospheric processes, their land surface interactions, and subsequently, realistic distribution of climatic fields in complex terrains. Given that such potential is yet to be explored within the central Himalayan region of Nepal, we investigate the skill of the Weather Research and Forecasting (WRF) model with different spatial resolutions in reproducing the spatial, seasonal, and diurnal characteristics of the near-surface air temperature and precipitation as well as the spatial shifts in the diurnal monsoonal precipitation peak over the Khumbu (Everest), Rolwaling, and adjacent southern areas. Therefore, the ERA-Interim (0.75°) reanalysis has been dynamically refined to 25, 5, and 1 km (D1, D2, and D3) for one complete hydrological year (October 2014-September 2015), using the one-way nested WRF model run with mild nudging and parameterized convection for the outer but explicitly resolved convection for the inner domains. Our results suggest that D3 realistically reproduces the monsoonal precipitation, as compared to its underestimation by D1 but overestimation by D2. All three resolutions, however, overestimate precipitation from the westerly disturbances, owing to simulating anomalously higher intensity of few intermittent events. Temperatures are generally reproduced well by all resolutions; however, winter and pre-monsoon seasons feature a high cold bias for high elevations while lower elevations show a simultaneous warm bias. Unlike higher resolutions, D1 fails to realistically reproduce the regional-scale nocturnal monsoonal peak precipitation observed in the Himalayan foothills and its diurnal shift towards high elevations, whereas D2 resolves these characteristics but exhibits a limited skill in reproducing such a peak on the river valley scale due to the limited representation of the narrow valleys at 5 km resolution. Nonetheless, featuring a substantial skill over D1 and D2, D3 simulates almost realistic shapes of the seasonal and diurnal precipitation and the peak timings even on valley scales. These findings clearly suggest an added value of the convective-scale resolutions in realistically resolving the topoclimates over the central Himalayas, which in turn allows simulating their interactions with the synoptic-scale weather systems prevailing over high Asia.

The use of IFSAR data in GIS-based landslide susceptibility evaluation

NASA Astrophysics Data System (ADS)

Floris, M.; Squarzoni, C.; Hundseder, C.; Mason, M.; Genevois, R.

2010-05-01

GIS-based landslide susceptibility evaluation is based on the spatial relationships between landslides and their related factors. The analyses are highly conditioned by precision and accuracy of input factors, in particular landslides identification and characterization. Factors influencing landslide spatial hazard consist of geological, geomorphological, hydrogeological and tectonic features, geomechanical and geotechnical properties, land use and management, and DEM-derived factors (elevation, slope, aspect, curvature, superficial flow). The choice of influencing factors depends on: method of analysis, scale of inputs, aim of the outputs, availability and quality of the input data. Then, the choice can be made a priori, on the bases of an in-deep territorial knowledge and experts' judgements, or by performing statistical analyses, finalized to identify the significance of each of the influencing factor. Due to the large availability of terrain data, spatial models often include DEM-derived factors, but the resolution and accuracy of DEMs influence the final outputs. In this work the relationships between landslides occurred in the volcanic area of the Euganean Hills Regional Park (SE of Padua, Veneto region, Italy) and morphometric factors (slope, aspect and curvature) will be examined through a simple probability method. The use of complex and time consuming mathematical or statistical models is not always recommended, because often simple models can lead to more accurate results. Morphometric input factors are derived from DEMs created from vector elevation data of the regional cartography at 1:5.000 scale and with NEXTMap® data (http://www.intermap.com). NEXTMap® Digital Surface Model (DSM) and Digital Terrain Model (DTM) are generated using Intermap's IFSAR (Interferometric Synthetic Aperture Radar) technology mounted on an aircraft at a flight height of 8500 m above Mean Sea Level and under a side viewing angle of about 45°. The DSM represents the first reflective surface as illuminated by the radar. IFSAR sensors retrieve the mean height of the main scattering elements in a grid cell, known as the scattering phase centre height. The radar return from vegetation usually penetrates to some extend lower than the ‘first' tree canopy height. The DTM is derived from DSM applying a semi-automated process that classifies areas as obstructed (buildings and vegetation) and unobstructed , where the obstructed areas are processed to approximate bald earth. DSM and DTM data present a post spacing of 5 m and a vertical accuracy of 1 m (RMSE) or better in areas of unobstructed flat terrain. IFSAR elevation models are compared with photogrammetrically derived models (topographic map of Veneto Region) for the following aspects: Every elevation point of IFSAR models is derived through a direct measure of the terrain surface, while photogrammetric elevation models are usually compiled through digitalization and interpolation of contour lines. Frequent seam lines are evident in vector maps derived DEMs, compiled during many years, with different specifications and tools. IFSAR 5 m posted DEM's generate a much more detailed description of terrain features. Seamless and homogeneous IFSAR elevation models pave the way to accurate applications like landslides study and risk assessment. The results obtained using the two DEM sources will be compared. The contribution of IFSAR data to the GIS-based spatial analysis of the study area will be tested and discussed.

The Global Positioning System

USGS Publications Warehouse

,

1999-01-01

The Global Positioning System (GPS) is a constellation of navigation satellites called Navigation Satellite Timing And Ranging (NAVSTAR), maintained by the U.S. Department of Defense. Many outdoor enthusiasts recognize that a handheld GPS receiver can be an accurate tool for determining their location on the terrain. The GPS receiver helps determine locations on the Earth's surface by collecting signals from three or more satellites through a process called triangulation. Identifying a location on the Earth is more useful if you also know about the surrounding topographic conditions. Using a topographic map with the GPS receiver provides important information about features of the surrounding terrain and can help you plot an effective route from one location to another.

Abyssal hills: Influence of topography on benthic foraminiferal assemblages

NASA Astrophysics Data System (ADS)

Stefanoudis, Paris V.; Bett, Brian J.; Gooday, Andrew J.

2016-11-01

Abyssal plains, often thought of as vast flat areas, encompass a variety of terrains including abyssal hills, features that constitute the single largest landscape type on Earth. The potential influence on deep-sea benthic faunas of mesoscale habitat complexity arising from the presence of abyssal hills is still poorly understood. To address this issue we focus on benthic foraminifera (testate protists) in the >150-μm fraction of Megacorer samples (0-1 cm layer) collected at five different sites in the area of the Porcupine Abyssal Plain Sustained Observatory (NE Atlantic, 4850 m water depth). Three sites are located on the tops of small abyssal hills (200-500 m elevation) and two on the adjacent abyssal plain. We examined benthic foraminiferal assemblage characteristics (standing stock, diversity, composition) in relation to seafloor topography (hills vs. plain). Density and rarefied diversity were not significantly different between the hills and the plain. Nevertheless, hills do support a higher species density (i.e. species per unit area), a distinct fauna, and act to increase the regional species pool. Topographically enhanced bottom-water flows that influence food availability and sediment type are suggested as the most likely mechanisms responsible for these differences. Our findings highlight the potential importance of mesoscale heterogeneity introduced by relatively modest topography in regulating abyssal foraminiferal diversity. Given the predominance of abyssal hill terrain in the global ocean, we suggest the need to include faunal data from abyssal hills in assessments of abyssal ecology.

A transport model for computer simulation of wildfires

DOE Office of Scientific and Technical Information (OSTI.GOV)

Linn, R.

1997-12-31

Realistic self-determining simulation of wildfires is a difficult task because of a large variety of important length scales (including scales on the size of twigs or grass and the size of large trees), imperfect data, complex fluid mechanics and heat transfer, and very complicated chemical reactions. The author uses a transport approach to produce a model that exhibits a self-determining propagation rate. The transport approach allows him to represent a large number of environments such as those with nonhomogeneous vegetation and terrain. He accounts for the microscopic details of a fire with macroscopic resolution by dividing quantities into mean andmore » fluctuating parts similar to what is done in traditional turbulence modeling. These divided quantities include fuel, wind, gas concentrations, and temperature. Reaction rates are limited by the mixing process and not the chemical kinetics. The author has developed a model that includes the transport of multiple gas species, such as oxygen and volatile hydrocarbons, and tracks the depletion of various fuels and other stationary solids and liquids. From this model he develops a simplified local burning model with which he performs a number of simulations that demonstrate that he is able to capture the important physics with the transport approach. With this simplified model he is able to pick up the essence of wildfire propagation, including such features as acceleration when transitioning to upsloping terrain, deceleration of fire fronts when they reach downslopes, and crowning in the presence of high winds.« less

A survey of modelling methods for high-fidelity wind farm simulations using large eddy simulation.

PubMed

Breton, S-P; Sumner, J; Sørensen, J N; Hansen, K S; Sarmast, S; Ivanell, S

2017-04-13

Large eddy simulations (LES) of wind farms have the capability to provide valuable and detailed information about the dynamics of wind turbine wakes. For this reason, their use within the wind energy research community is on the rise, spurring the development of new models and methods. This review surveys the most common schemes available to model the rotor, atmospheric conditions and terrain effects within current state-of-the-art LES codes, of which an overview is provided. A summary of the experimental research data available for validation of LES codes within the context of single and multiple wake situations is also supplied. Some typical results for wind turbine and wind farm flows are presented to illustrate best practices for carrying out high-fidelity LES of wind farms under various atmospheric and terrain conditions.This article is part of the themed issue 'Wind energy in complex terrains'. © 2017 The Author(s).

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.

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.

Analyzing wind turbine flow interaction through vibration data

NASA Astrophysics Data System (ADS)

Castellani, Francesco; D'Elia, Gianluca; Astolfi, Davide; Mucchi, Emiliano; Giorgio, Dalpiaz; Terzi, Ludovico

2016-09-01

Wind turbines commonly undergo non-stationary flow and, not rarely, even rather extreme phenomena. In particular, rough terrains represent a challenging testing ground, because of the combination of terrain-driven flow and wakes. It is therefore crucial to assess the impact of dynamic loads on the turbines. In this work, tower and drive-train vibrations are analyzed, from a subcluster of four turbines of a wind farm sited in a very complex terrain. The main outcome of the study is that it is possible to start from the analysis of wind conditions and interpret how wakes manifest in the vibrations of the turbines, both at structural level (tower vibrations) and at the drive-train level. This wind to gear approach therefore allows to build a connection between a flow phenomenon and a mechanical phenomenon (vibrations) and can be precious to assess loads in different working conditions.

Planetary Analogs in Antarctica: Icy Satellites

NASA Technical Reports Server (NTRS)

Malin, M. C.

1985-01-01

As part of a study to provide semi-quantitative techniques to date past Antarctic glaciations, sponsored by the Antarctic Research Program, field observations pertinent to other planets were also acquired. The extremely diverse surface conditions, marked by extreme cold and large amounts of ice, provide potential terrain and process analogs to the icy satellites of Jupiter and Saturn. Thin ice tectonic features and explosion craters (on sea ice) and deformation features on thicker ice (glaciers) are specifically addressed.