Digital Terrain Elevation Data Research Articles

Mapping of landslide susceptibility using analytical hierarchy process on the example of the right bank of the Kaniv Reservoir

The study of landslide-prone areas requires the analysis of a large amount of objective data, products of remote sensing data processing (spatial images, digital terrain elevation data and analytical data on calculated indices), analytical maps based on field measurements. All these data make it possible to objectively and more accurately characterize the studied territory. It is important, based on the results of the assessment, to get a conclusion about favorable, unfavorable and dangerous areas. The result is a landslide susceptibility map. In this study, we carried out the procedure of creating a landslide susceptibility map at the regional level for the Rzhyshchiv united territorial community of the Kyiv region. Nine factors that influence the development of landslides or become indicators of landslide processes are selected. A description of the algorithm for creating a landslide susceptibility map using the method of hierarchical analysis is provided. The obtained result gives an idea of the different propensity of the areas of the studied territory to the development of landslide processes, it means the areas of the greatest threats, which contributes to the rational adoption of management decisions.

A turbulent orographic form drag scheme accounting for anisotropy and orientation for kilometer‐ to subkilometer‐scale models

AbstractThis paper presents a turbulent orographic form drag (TOFD) parameterization scheme that takes into account the directional effects stemming from the angle between the low‐level wind and the principal axis of small‐scale orography. Suitable for models with both kilometer and subkilometer horizontal resolutions, this scheme builds upon prior theoretical and numerical studies to formulate surface TOFD based on the slope and direction of the sinusoidal hills. In this study, we proposed a straightforward function to calculate the surface TOFD for various orographic aspect ratios and directional parameters. The vertical decay of the drag is modeled with a scale twice the standard deviation of the sub‐grid orography. A comparison with numerous large‐eddy simulations featuring a single ellipsoidal hill demonstrates that our scheme effectively captures the dependence of drag on factors such as maximum slope, aspect ratio, the angle between low‐level wind and the principle axis, and hill height. We recommend calculating the sub‐grid orographic parameters using a well‐established method and digital terrain elevation data with a horizontal resolution less than a 100 m. This will allow for representation on orographic scales of both kilometers and subkilometers. Real‐case numerical weather prediction tests are conducted and verified with dense surface wind observations. The proposed scheme improves surface wind simulation compared to a renowned TOFD scheme, and also effectively exhibits the wind response to orographic anisotropy.

On the accuracy of an emitter localization method based on multipath exploitation in realistic scenarios

This study aims to evaluate the accuracy of a method proposed for passive localization of radar emitters around irregular terrains with a single receiver in Electronic Support Measures systems. Previously, the authors targeted only the theoretical development of the localization method. In fact, this could be a serious concern in practice since there is no evidence regarding its accuracy under the real data gathered from realistic scenarios. Therefore, an accurate ray-tracing algorithm is adapted to enable the implementation of the method in practice. Then, realistic scenarios are determined based on the geographic information system map generated to collect high-resolution digital terrain elevation data, as well as realistic localization problems for radar emitters. Next, simulations are performed to test the localization method. Thus, the performance of the method is verified for practical implementation in the electronic warfare context for the first time. Lastly, the performance bounds of the method are discussed.

The Sierra Nevada de Santa Marta (Colombia) and Nevado de Famatina (Argentina): The effects of tectonic syntaxis on the topography of the Andes

The Sierra Nevada de Santa Marta (Santa Marta) in Colombia and Nevado del Famatina (Famatina) in Argentina are two isolated peaks within the Andes of South America, having elevations of about 5,500 and 6,000 m, respectively. Both massifs are bounded by major wrench faults of opposite kinematics but comparable magnitude in their lateral displacement. Despite the volumes of research available, little has been said in the literature about the tectonics surrounding these particular systems. In this context, digital terrain elevation (DEM), regional geology, satellite imagery and geophysical data were analysed to illustrate how a network of transcurrent faults uplifted the peaks. We propose a model to account for topography by the opposed movement of faults operating in two compartments: internal (acute) and external (obtuse). Fault motion caused uplift of the internal compartments: a) the Santa Marta tectonic syntaxis is generated by the sinistral Santa Marta-Bucaramanga Fault on the west and the dextral Oca-Pilar Fault to the north whilst, b) the Famatina tectonic syntaxis is caused by the Valle Fértil sinistral fault on the western side and the dextral Tucumán lineament to the north. Elevation maps documenting the lateral displacement of modern alluvial fans provide evidence of the existence and kinematics of these faults. Active since the Neogene, the transcurrent faults resulted in displacements in the order of 25–60 km, with velocities of approximately 1–2 cm/year. Seismic records suggest that the syntaxis occurred after reactivation of oblique discontinuities in the basement due to the convergence of the Nazca, Caribbean, and South American plates. This tectonic framework led to the formation of a remarkable positive relief and the development of internal positive compartments subject to constrictive forces. Simultaneously, external distensive and negative compartments controlled the syntectonic deposition of thick sedimentary sequences. The significant topographic difference between the internal positive compartments and their external negative counterparts triggered high rates of erosion, transport, and ultimately sedimentation. Regional subsurface surveys indicate strong anomalies of the underlying bedrock influenced by tectonic syntaxis.

Ground Target Tracking Using an Airborne Angle-Only Sensor with Terrain Uncertainty and Sensor Biases.

Airborne angle-only sensors can be used to track stationary or mobile ground targets. In order to make the problem observable in 3-dimensions (3-D), the height of the target (i.e., the height of the terrain) from the sea-level is needed to be known. In most of the existing works, the terrain height is assumed to be known accurately. However, the terrain height is usually obtained from Digital Terrain Elevation Data (DTED), which has different resolution levels. Ignoring the terrain height uncertainty in a tracking algorithm will lead to a bias in the estimated states. In addition to the terrain uncertainty, another common source of uncertainty in angle-only sensors is the sensor biases. Both these uncertainties must be handled properly to obtain better tracking accuracy. In this paper, we propose algorithms to estimate the sensor biases with the target(s) of opportunity and algorithms to track targets with terrain and sensor bias uncertainties. Sensor bias uncertainties can be reduced by estimating the biases using the measurements from the target(s) of opportunity with known horizontal positions. This step can be an optional step in an angle-only tracking problem. In this work, we have proposed algorithms to pick optimal targets of opportunity to obtain better bias estimation and algorithms to estimate the biases with the selected target(s) of opportunity. Finally, we provide a filtering framework to track the targets with terrain and bias uncertainties. The Posterior Cramer–Rao Lower Bound (PCRLB), which provides the lower bound on achievable estimation error, is derived for the single target filtering with an angle-only sensor with terrain uncertainty and measurement biases. The effectiveness of the proposed algorithms is verified by Monte Carlo simulations. The simulation results show that sensor biases can be estimated accurately using the target(s) of opportunity and the tracking accuracies of the targets can be improved significantly using the proposed algorithms when the terrain and bias uncertainties are present.

Ground Moving Target Tracking Filter Considering Terrain and Kinematics.

This paper addresses ground target tracking (GTT) for airborne radar. Digital terrain elevation data (DTED) are widely used for GTT as prior information under the premise that ground targets are constrained on terrain. Existing works fuse DTED to a tracking filter in a way that adopts only the assumption that the position of the target is constrained on the terrain. However, by kinematics, it is natural that the velocity of the moving ground target is constrained as well. Furthermore, DTED provides neither continuous nor accurate measurement of terrain elevation. To overcome such limitations, we propose a novel soft terrain constraint and a constraint-aided particle filter. To resolve the difficulties in applying the DTED to the GTT, first, we reconstruct the ground-truth terrain elevation using a Gaussian process and treat DTED as a noisy observation of it. Then, terrain constraint is formulated as joint soft constraints of position and velocity. Finally, we derive a Soft Terrain Constrained Particle Filter (STC-PF) that propagates particles while approximately satisfying the terrain constraint in the prediction step. In the numerical simulations, STC-PF outperforms the Smoothly Constrained Kalman Filter (SCKF) in terms of tracking performance because SCKF can only incorporate hard constraints.

Path Loss Analysis Considering Atmospheric Refractivity and Precipitation for Air-to-Ground Radar

This letter reports a correlation analysis of path loss considering atmospheric refractivity and precipitation in an air-to-ground radar application. For the path loss estimation, the refractivity and rainfall attenuation models are derived using actual atmospheric data. The path loss along the range and altitude is obtained using parabolic equation software tool (PETOOL). The digital terrain elevation data (DTED) of the Suwon-Osan area, the radar antenna beam pattern, and environmental models are employed in the PETOOL. Then, we expand the path loss calculation in an azimuthal scan to observe the illuminated field intensity on the ground for a synthetic aperture radar (SAR) application. The results confirm that the illuminated field intensity for SAR applications is closely related to refractivity and precipitation.

The NCAR Airborne 94-GHz Cloud Radar: Calibration and Data Processing

The 94-GHz airborne HIAPER Cloud Radar (HCR) has been deployed in three major field campaigns, sampling clouds over the Pacific between California and Hawaii (2015), over the cold waters of the Southern Ocean (2018), and characterizing tropical convection in the Western Caribbean and Pacific waters off Panama and Costa Rica (2019). An extensive set of quality assurance and quality control procedures were developed and applied to all collected data. Engineering measurements yielded calibration characteristics for the antenna, reflector, and radome, which were applied during flight, to produce the radar moments in real-time. Temperature changes in the instrument during flight affect the receiver gains, leading to some bias. Post project, we estimate the temperature-induced gain errors and apply gain corrections to improve the quality of the data. The reflectivity calibration is monitored by comparing sea surface cross-section measurements against theoretically calculated model values. These comparisons indicate that the HCR is calibrated to within 1–2 dB of the theory. A radar echo classification algorithm was developed to identify “cloud echo” and distinguish it from artifacts. Model reanalysis data and digital terrain elevation data were interpolated to the time-range grid of the radar data, to provide an environmental reference.

Monitoring terrain elevation of intertidal wetlands by utilising the spatial-temporal fusion of multi-source satellite data: A case study in the Yangtze (Changjiang) Estuary

Intertidal wetlands are dynamic geomorphological areas located at the land-sea interface and perform multiple ecosystem functions. Owing to increased human activities, intertidal wetlands have been subjected to dramatic changes in recent decades; therefore, high-resolution monitoring of wetland topography is critical to its management. However, satellite imagery with high spatial resolution usually demonstrates a low revisit frequency (e.g. several days to greater than ten days) and is frequently obstructed by clouds, limiting its capability to display the high-resolution time-series information of intertidal wetland terrain elevation variations. Conversely, satellite imagery with a high revisit frequency generally demonstrates a lower spatial resolution. In this study, a spatial-temporal data fusion method was utilised to generate hourly time-series images with a spatial resolution of 16 m by combining the satellite GF-1/WFV data (spatial resolution: 16 m; revisit frequency: 4 days) with geostationary satellite GOCI data (spatial resolution: 500 m; revisit frequency: 1 h). In combination with the tidal level information, digital terrain elevation (DTM) data of the intertidal wetland can be derived from fusion images. The DTM was synchronously validated by the terrain elevation data acquired on the same day utilising unmanned aerial vehicle (UAV)-borne LiDAR in the North Branch intertidal wetland of Chongming Island, Yangtze Estuary, with a root mean square error of 0.16 m. The application in Chongming-Dongtan indicates that this method is effective for monitoring high dynamic changes in intertidal wetland terrain elevations.

A Novel LOS Decision Technique Reflecting 3D DTED for Modeling an Electronic Warfare Environment

A new line-of-sight (LOS) decision algorithm applicable to simulation of electronic warfare (EW) is developed. For accurate simulation, the digital terrain elevation data (DTED) of the region to be analyzed must be reflected in the simulation, and millions of datasets are necessary in the EW environment. In order to obtain real-time results in such an environment, a technology that determines line-of-sight (LOS) quickly and accurately is very important. In this paper, a novel algorithm is introduced for determining LOS that can be applied in an EW environment with three-dimensional (3D) DTED. The proposed method shows superior performance as compared with the simplest point-to-point distance calculation method and it is also 50% faster than the conventional interpolation method. The DTED used in this paper is the data applied as level 0 for the Republic of Korea, and the decision of the LOS at approximately 1.8 million locations viewed by a reconnaissance plane flying 10 km above the ground is determined within 0.026 s.

Assessment of tectonic control on the development of low mountains moderate relief in the Outer Carpathians (Southern Poland)

Inherited tectonic structures, ongoing tectonic deformation, and variations in relative rock uplift rates play an important role in conditioning the processes of relief development. Their influence among other factors, such as climate and lithology, can be quantified using landscape analysis, and geomorphometric indices, in particular. The usage of landscape analysis in recent years is increasing systematically due to the constant improvement of the digital elevation models and GIS software that significantly facilitate this approach. In this study, we aim to recognize the influence of tectonic structures and processes on relief development in the low mountains with moderate relief of the Soła River catchment in the Western Outer Carpathians. To this end, we calculated geomorphometric indices (river longitudinal profile, stream-length gradient index, minimum bulk erosion, relief ratio, circulatory ratio, elongation ratio, and hypsometric integral) for the Sola River and its 47 sub-catchments using a 25-m spatial resolution Digital Terrain Elevation Data Level 2. Additionally, we identified lineaments and knickpoints and correlated the computed results with local and regional fault networks, variations in lithology, and climate fluctuations. Obtained results indicate a significant impact of inherited tectonic structures on the relief development of the Soła River catchment, i.e., directions of principal ridges and valleys follow the orientation of main folds and faults recorded in this area. Anomalously high values of minimum bulk erosion, river gradient, and stream-length gradient index allowed us to define two areas with higher relative uplift rates: 1) the Sola Gorge and 2) the Beskid Żywiecki Mts. Polish Outer Carpathians are generally considered as an area of low strain rate and low seismic activity. However, the possibility of neotectonic processes should be considered in geohazard estimations. Observed bends in the direction of river valleys that do not correspond with changes in lithology could be related to active strike-slip faults. These are probably the reactivated basement structures, copied in the thin-skinned nappe cover, as a result of the accommodation of the Mur-Žilina Fault Zone resulting from the tectonic push of the Alcapa (Alpine-Carpathian-Pannonian) microplate against the European plate. Thus, the role of recent tectonic activity in relief development of the Sola River catchment even though appears to be subsidiary at the most, should not be excluded.

Analysis of the Target Detection Performance of Air-to-Air Airborne Radar Using Long-Range Propagation Simulation in Abnormal Atmospheric Conditions

In this paper, we propose the analysis of the target detection performance of air-to-air airborne radars using long-range propagation simulations with a novel quad-linear refractivity model under abnormal atmospheric conditions. The radar propagation characteristics and the target detection performance are simulated using the Advanced Refractive Effects Prediction System (AREPS) software, where the refractivity along the altitude, array antenna pattern, and digital terrain elevation data are considered as inputs to obtain the path loss of the wave propagation. The quad-linear model is used to approximate the actual refractivity data, which are compared to the data derived using the conventional trilinear refractivity model. On the basis of the propagation simulations, we propose a detection performance metric in terms of the atmosphere (DPMA) for intuitively examining the long-range propagation characteristics of airborne radars in air-to-air situations. To confirm the feasibility of using the DPMA map in various duct scenarios, we employ two actual refractive indices to observe the DPMA results in relation to the height of the airborne radar.

PETOOL v2.0: Parabolic Equation Toolbox with evaporation duct models and real environment data

A new version of PETOOL (Parabolic Equation Toolbox) is introduced with various additional capabilities. PETOOL is an open-source and MATLAB-based software tool with a user-friendly graphical user interface (GUI) for the analysis and visualization of electromagnetic wave propagation over variable terrain and through arbitrary atmosphere. Four novel features of the second version are as follows: (i) Several evaporation duct models have been developed. (ii) Real atmosphere data have been included in the form of “Binary Universal Form for Representation (BUFR)” data developed by “World Meteorological Organization (WMO)”. (iii) Real terrain data have been incorporated into the toolbox in the form of “Digital Terrain Elevation Data (DTED)” developed by “National Imagery and Mapping Agency (NIMA)”. (iv) A special add-on has been developed to generate a 3D coverage map of propagation factor/loss on real terrain data. The toolbox can be used for research and/or educational purposes to analyze more realistic propagation scenarios in an easier and flexible manner. Program summaryProgram title: PETOOL v2.0 (Parabolic Equation Toolbox v2.0)CPC Library link to program files:http://dx.doi.org/10.17632/v8f42rn2zs.1Licensing provisions: GNU General Public License 3Programming language: MATLAB (MathWorks Inc.) R2019a. Partial Differential Toolbox, Curve Fitting Toolbox and Mapping Toolbox required.Journal Reference of previous version: O. Ozgun, G. Apaydin, M. Kuzuoglu, and L. Sevgi, PETOOL: MATLAB-based one-way and two-way split-step parabolic equation tool for radiowave propagation over variable terrain, Computer Physics Communications 182 (2011) 2638–2654.Does the new version supersede the previous version?: YesReasons for the new version: The new version of the toolbox has been enriched with several add-ons which allow the toolbox to make more realistic analyses with real terrain and atmospheric data. The toolbox has the ability to read real atmospheric data in the form of BUFR data and real terrain data in the form of DTED data. A wide range of evaporation duct models has been incorporated into the toolbox. A special add-on has been developed to generate a 3D coverage map of propagation factor/loss on real terrain data. Hence, the toolbox can be used to analyze more realistic propagation scenarios in an easier and flexible manner.Summary of revisions: (i) Several evaporation duct models have been included with real atmospheric data in BUFR format. (ii) Real terrain data in DTED format have been incorporated into the toolbox. (iii) A special add-on has been developed to generate a 3D coverage map of propagation factor/loss on real terrain data.Nature of problem: This program is designed with a user-friendly GUI for the analysis and visualization of radio-wave propagation over variable terrain on the Earth’s surface, and through homogeneous and inhomogeneous atmosphere by using real atmosphere and terrain data. It can easily model both horizontally- and vertically-varying atmospheric refraction (especially ducting) and multipath effects.Solution method: The program employs one-way and two-way Split-Step Parabolic Equation (SSPE) algorithms with a wide-angle propagator. The SSPE is an initial-value problem starting from a reference range (typically from an antenna), and marching out in range by obtaining the field along the vertical direction at each range step, through the use of step-by-step Fourier transformations. The two-way algorithm incorporates the backward-propagating waves into the standard one-way SSPE by utilizing an iterative forward–backward scheme for modeling multipath effects over a staircase-approximated terrain.

Development and Evaluation of Hourly and Kilometer Resolution Retrospective and Real-Time Surface Meteorological Blended Forcing Dataset (SMBFD) in China

A real-time, long-term surface meteorological blended forcing dataset (SMBFD) has been developed based on station observations, satellite retrievals, and reanalysis products in China. The observations are collected at national and regional automatic weather stations, satellite data are obtained from the Fengyun (FY) series satellites retrievals, and the reanalysis products are obtained from the ECMWF. The 90-m resolution digital terrain elevation data in China are obtained from the Shuttle Radar Topographic Mission (SRTM) for temperature and humidity elevation adjustment. The dataset includes 2-m air temperature and humidity, 10-m zonal and meridional winds, downward shortwave radiation, surface pressure, and precipitation. The spatial resolution is 1 km, and the temporal resolution is 1 h. During the data processing procedure, various data fusion techniques including the space–time multiscale variational analy-sis, the discrete ordinates radiative transfer (DISORT) model, the hybrid radiation estimation model, and a terrain correction algorithm are employed. Dependent and independent evaluations of the dataset are performed against observations. The SMBFD dataset is also compared with similar datasets produced in other major meteorological operational centers in the world. The results are as follows. (1) All variables show reasonable geographic distribution features and realistic spatial and temporal variations. (2) Dependent and independent evaluations both indicate that the gridded SMBFD dataset is close to the observations, while the dependent evaluation yields better results than the independent evaluation. (3) Compared with similar datasets produced in other meteorological operational centers, the real-time and retrospective surface meteorological fusion data obviously have higher quality. The dataset introduced in the present study is in general stable and accurate, and can be applied in various practice such as meteorology, agriculture, ecology, environmental protection, etc. Meanwhile, this dataset has been used as the atmospheric forcing data to drive the operational High-resolution Land Data Assimilation System of China Meteorological Administration. The dataset with the network Common Data Form (NETCDF) can be decoded by various programming languages, and it is freely available to non-commercial users.

Evaluation of TanDEM-X 90 m Digital Elevation Model

ABSTRACTGerman Aerospace Center (DLR), EADS Astrium GmbH and Infoterra GmbH alliance came up with the idea of taking DTED-2 (Digital terrain elevation data, level-2) specifications to even higher standard of HRTE-3 (High resolution terrain elevation, level-3) in 2006, as a result TDX (TerraSAR-X, TanDEM-X) constellation was born. The mission was geared to create a rather sensitive, high precision 3 dimensional map of the entire Earth in seamless and very high quality. After Shuttle Radar Topography Mission (SRTM) in 2000 and its derivatives, along with numerous prior and subsequent other similar data, have practically set the standard for defining the topographical surfaces in global scale, the twin satellites acquired all of Earth’s land surfaces numerous times to produce varying resolution digital elevation models (DEM) between 2011 and late 2015. DEMs are widely used in many planning, decision making and engineering related projects. They provide sound backing for mankind’s endeavors. Ground resolution is the most sought after feature of any DEM. Finer resolution is usually associated with a better surface definition. Recently, an entirely new global DEM has been released DLR. The 90 m DEM is the latest variant derived from such an undertaking. This study aimed to examine the overall effectiveness of this alleged new data in four previously surveyed locations and against the performances of finer SRTM 1- and comparable SRTM 3 arc second data. The results showed that TanDEM-X 90 m data overestimated. They seemed to be rather accurate in flat to slightly undulating terrain, but overestimated in broken to treacherous terrain than both SRTMs. Root Mean Square Error was greater in site one and site four, and lower in site two and site three compared to both SRTM 1 and SRTM 3 arc second data.

Acquisition method for terrain referenced navigation using terrain contour intersections

This study presents a contour intersection-based acquisition method for fast and robust terrain referenced navigation (TRN). Due to advances in highly accurate sensors, such as in radar and lasers, the shortcomings of past TRN could be overcome. High-performance sensors have made it possible to estimate the true terrain height limited to narrow error intervals. Digital terrain elevation data is employed for the purpose of inversely obtaining the measurement area – the area created by contours – corresponding to the height interval. Since the measurement area is a bundle of contour lines, the intersection area, which is the intersection of measurement areas, consists of a set of intersections of contour lines. Intersection areas are sequentially obtained to estimate the actual aircraft position. While batch processing is computationally expensive and it is hard to produce solutions until the position is fixed, the proposed method is fast enough to provide a rapid solution without an initial break. Sequential processing is sensitive to initial position errors, whereas the proposed method proves to be robust. The simulation results show that the contour intersection-based acquisition method provides improved navigation performance for various terrain samples.

Uncertainties in the Shuttle Radar Topography Mission (SRTM) Heights: Insights from the Indian Himalaya and Peninsula

The Shuttle Radar Topography Mission (SRTM) Digital Terrain Elevation Data (DTED) are used with the consensus view that it has a minimum vertical accuracy of 16 m absolute error at 90% confidence (Root Mean Square Error (RMSE) of 9.73 m) world-wide. However, vertical accuracy of the data decreases with increase in slope and elevation due to presence of large outliers and voids. Therefore, studies using SRTM data “as is”, especially in regions like the Himalaya, are not statistically meaningful. New data from ~200 high-precision static Global Position System (GPS) Independent Check Points (ICPs) in the Himalaya and Peninsular India indicate that only 1-arc X-Band data are usable “as is” in the Himalaya as it has height accuracy of 9.18 m (RMSE). In contrast, recently released (2014–2015) “as-is” 1-arc and widely used 3-arc C-Band data have a height accuracy of RMSE 23.53 m and 47.24 m and need to be corrected before use. Outlier and void filtering improves the height accuracy to RMSE 8 m, 10.14 m, 14.38 m for 1-arc X and C-Band and 3-arc C-Band data respectively. Our study indicates that the C-Band 90 m and 30 m DEMs are well-aligned and without any significant horizontal offset implying that area and length computations using both the datasets have identical values.

Vision-based navigation for unmanned aircraft using ground feature points and terrain elevation data

A vision-based navigation approach using digital terrain elevation data and a monocular camera is addressed for autonomous navigation of unmanned aircraft. Previous vision-based terrain-referenced navigation algorithms use visual measurements to update vehicle position. This study expands the use of the visual measurements and the terrain data by designing the navigation filter to update 3-axis attitude and velocity as well as position. An observation model for updating position and attitude compares height estimates of ground features, computed from the visual measurements, with terrain elevation data. Additionally, the eight-point algorithm is adopted to extract direction of camera movement to update velocity in the navigation filter. A simulation study is conducted to verify the feasibility of the proposed method and the effect of visual measurement errors.

DS02R1: Improvements to Atomic Bomb Survivors' Input Data and Implementation of Dosimetry System 2002 (DS02) and Resulting Changes in Estimated Doses.

Individual dose estimates calculated by Dosimetry System 2002 (DS02) for the Life Span Study (LSS) of atomic bomb survivors are based on input data that specify location and shielding at the time of the bombing (ATB). A multi-year effort to improve information on survivors' locations ATB has recently been completed, along with comprehensive improvements in their terrain shielding input data and several improvements to computational algorithms used in combination with DS02 at RERF. Improvements began with a thorough review and prioritization of original questionnaire data on location and shielding that were taken from survivors or their proxies in the period 1949-1963. Related source documents varied in level of detail, from relatively simple lists to carefully-constructed technical drawings of structural and other shielding and surrounding neighborhoods. Systematic errors were reduced in this work by restoring the original precision of map coordinates that had been truncated due to limitations in early data processing equipment and by correcting distortions in the old (WWII-era) maps originally used to specify survivors' positions, among other improvements. Distortion errors were corrected by aligning the old maps and neighborhood drawings to orthophotographic mosaics of the cities that were newly constructed from pre-bombing aerial photographs. Random errors that were reduced included simple transcription errors and mistakes in identifying survivors' locations on the old maps. Terrain shielding input data that had been originally estimated for limited groups of survivors using older methods and data sources were completely re-estimated for all survivors using new digital terrain elevation data. Improvements to algorithms included a fix to an error in the DS02 code for coupling house and terrain shielding, a correction for elevation at the survivor's location in calculating angles to the horizon used for terrain shielding input, an improved method for truncating high dose estimates to 4 Gy to reduce the effect of dose error, and improved methods for calculating averaged shielding transmission factors that are used to calculate doses for survivors without detailed shielding input data. Input data changes are summarized and described here in some detail, along with the resulting changes in dose estimates and a simple description of changes in risk estimates for solid cancer mortality. This and future RERF publications will refer to the new dose estimates described herein as "DS02R1 doses."

Estudio Geomorfológico para la Ordenación del Espacio Litoral: Caso del Estuario del Río Purio, República de Panamá

Se analizan las unidades geomorfológicas y las geoformas de la zona marino-costera de la cuenca hidrográfica del río Purio (República de Panamá), con el objetivo de analizar las evidencias que permitan discriminar las características geomorfológicas de la franja litoral y de la costa. Para ello se ha dispuesto de los procedimientos de realce de bandas y eliminación de ruidos aplicados sobre la imagen Rapid Eyes (2012), en ambiente SPRING, y del uso de los productos derivados del geoprocesamiento de la imagen SRTM – DTED (2011) (Digital Terrain Elevation Data), en ambiente ArcMap (curvas de nivel, datos hipsométricos y pendientes), además de la verificación de campo. Los resultados de las interpolaciones en SIG y el trabajo de campo indican que los cordones litorales constituidos por flechas, paleo-flechas, dunas frontales y bancos de arenas, y la planicie fluvio-marina, colonizada por Rhizophora mangle, forman parte de las unidades geomorfológicas litorales que se internan decenas de metros sobre la costa. No obstante, se sustenta la necesidad de reconocer las especies bio-indicadoras para fundamentar la dinámica de la geobiocenosis en cada una de las unidades geomorfológicas y geoformas que integran la zona marino-costera.