Science.gov

Sample records for 30-m resolution estimates

  1. Developing a 30-m grassland productivity estimation map for central Nebraska using 250-m MODIS and 30-m Landsat-8 observations

    USGS Publications Warehouse

    Gu, Yingxin; Wylie, Bruce K.

    2015-01-01

    Accurately estimating aboveground vegetation biomass productivity is essential for local ecosystem assessment and best land management practice. Satellite-derived growing season time-integrated Normalized Difference Vegetation Index (GSN) has been used as a proxy for vegetation biomass productivity. A 250-m grassland biomass productivity map for the Greater Platte River Basin had been developed based on the relationship between Moderate Resolution Imaging Spectroradiometer (MODIS) GSN and Soil Survey Geographic (SSURGO) annual grassland productivity. However, the 250-m MODIS grassland biomass productivity map does not capture detailed ecological features (or patterns) and may result in only generalized estimation of the regional total productivity. Developing a high or moderate spatial resolution (e.g., 30-m) productivity map to better understand the regional detailed vegetation condition and ecosystem services is preferred. The 30-m Landsat data provide spatial detail for characterizing human-scale processes and have been successfully used for land cover and land change studies. The main goal of this study is to develop a 30-m grassland biomass productivity estimation map for central Nebraska, leveraging 250-m MODIS GSN and 30-m Landsat data. A rule-based piecewise regression GSN model based on MODIS and Landsat (r = 0.91) was developed, and a 30-m MODIS equivalent GSN map was generated. Finally, a 30-m grassland biomass productivity estimation map, which provides spatially detailed ecological features and conditions for central Nebraska, was produced. The resulting 30-m grassland productivity map was generally supported by the SSURGO biomass production map and will be useful for regional ecosystem study and local land management practices.

  2. Methodology to obtain 30 m resolution of snow cover area from FSCA MODIS and NDSI Landsat

    NASA Astrophysics Data System (ADS)

    Cepeda, Javier; Vargas, Ximena

    2016-04-01

    In the last years numerous free images and product satellites have been released, with different spatial and temporal resolution. Out of them, the most commonly used to describe the snow area are MODIS and Landsat. Fractional snow cover area (FSCA) is a daily MODIS product with a 500 m spatial resolution; Landsat images have around 16 days and 30 m respectively. In this work we use both images to obtain a new daily 30 m resolution snow distribution product based in probabilistic and geospatial information. This can be useful because a higher resolution can be used to improve the estimation of the accuracy of a physically-based distributed model to represent the snow cover distribution. We choose three basins in central Chile, with an important snow and glacier presence, to analyze the spatial and temporal distribution of snow using (1) the mean value between MOD10A1 (terra) and MYD10A1 (aqua) and (2) the corrected images by topography and atmosphere from Landsat 5 and Landsat 8 computing the normalized difference snow index (NDSI). When both satellites data are available in the same day, each MODIS pixel is studied considering the Landsat pixels contained in it. A new matrix is created, covering all MODIS pixels, using a 30 m spatial resolution, where each pixel value represents the probability of snow presence in time from Landsat images, and then each pixel is corrected by its neighbour's pixels, elevation, slope and aspect. Then snow is distributed, for each MODIS pixel, considering the corrected probability matrix and sorted between pixels with high probability until the area from FSCA is completed.

  3. Global land cover mapping at 30 m resolution: A POK-based operational approach

    NASA Astrophysics Data System (ADS)

    Chen, Jun; Chen, Jin; Liao, Anping; Cao, Xin; Chen, Lijun; Chen, Xuehong; He, Chaoying; Han, Gang; Peng, Shu; Lu, Miao; Zhang, Weiwei; Tong, Xiaohua; Mills, Jon

    2015-05-01

    Global Land Cover (GLC) information is fundamental for environmental change studies, land resource management, sustainable development, and many other societal benefits. Although GLC data exists at spatial resolutions of 300 m and 1000 m, a 30 m resolution mapping approach is now a feasible option for the next generation of GLC products. Since most significant human impacts on the land system can be captured at this scale, a number of researchers are focusing on such products. This paper reports the operational approach used in such a project, which aims to deliver reliable data products. Over 10,000 Landsat-like satellite images are required to cover the entire Earth at 30 m resolution. To derive a GLC map from such a large volume of data necessitates the development of effective, efficient, economic and operational approaches. Automated approaches usually provide higher efficiency and thus more economic solutions, yet existing automated classification has been deemed ineffective because of the low classification accuracy achievable (typically below 65%) at global scale at 30 m resolution. As a result, an approach based on the integration of pixel- and object-based methods with knowledge (POK-based) has been developed. To handle the classification process of 10 land cover types, a split-and-merge strategy was employed, i.e. firstly each class identified in a prioritized sequence and then results are merged together. For the identification of each class, a robust integration of pixel-and object-based classification was developed. To improve the quality of the classification results, a knowledge-based interactive verification procedure was developed with the support of web service technology. The performance of the POK-based approach was tested using eight selected areas with differing landscapes from five different continents. An overall classification accuracy of over 80% was achieved. This indicates that the developed POK-based approach is effective and feasible

  4. Mapping Impervious Surfaces Globally at 30m Resolution Using Global Land Survey Data

    NASA Technical Reports Server (NTRS)

    DeColstoun, Eric Brown; Huang, Chengquan; Tan, Bin; Smith, Sarah Elizabeth; Phillips, Jacqueline; Wang, Panshi; Ling, Pui-Yu; Zhan, James; Li, Sike; Taylor, Michael P.; Wolfe, Robert E.; Tilton, James C.

    2013-01-01

    Impervious surfaces, mainly artificial structures and roads, cover less than 1% of the world's land surface (1.3% over USA). Regardless of the relatively small coverage, impervious surfaces have a significant impact on the environment. They are the main source of the urban heat island effect, and affect not only the energy balance, but also hydrology and carbon cycling, and both land and aquatic ecosystem services. In the last several decades, the pace of converting natural land surface to impervious surfaces has increased. Quantitatively monitoring the growth of impervious surface expansion and associated urbanization has become a priority topic across both the physical and social sciences. The recent availability of consistent, global scale data sets at 30m resolution such as the Global Land Survey from the Landsat satellites provides an unprecedented opportunity to map global impervious cover and urbanization at this resolution for the first time, with unprecedented detail and accuracy. Moreover, the spatial resolution of Landsat is absolutely essential to accurately resolve urban targets such a buildings, roads and parking lots. With long term GLS data now available for the 1975, 1990, 2000, 2005 and 2010 time periods, the land cover/use changes due to urbanization can now be quantified at this spatial scale as well. In the Global Land Survey - Imperviousness Mapping Project (GLS-IMP), we are producing the first global 30 m spatial resolution impervious cover data set. We have processed the GLS 2010 data set to surface reflectance (8500+ TM and ETM+ scenes) and are using a supervised classification method using a regression tree to produce continental scale impervious cover data sets. A very large set of accurate training samples is the key to the supervised classifications and is being derived through the interpretation of high spatial resolution (approx. 2 m or less) commercial satellite data (Quickbird and Worldview2) available to us through the unclassified

  5. Mapping Impervious Surfaces Globally at 30m Resolution Using Landsat Global Land Survey Data

    NASA Astrophysics Data System (ADS)

    Brown de Colstoun, E.; Huang, C.; Wolfe, R. E.; Tan, B.; Tilton, J.; Smith, S.; Phillips, J.; Wang, P.; Ling, P.; Zhan, J.; Xu, X.; Taylor, M. P.

    2013-12-01

    Impervious surfaces, mainly artificial structures and roads, cover less than 1% of the world's land surface (1.3% over USA). Regardless of the relatively small coverage, impervious surfaces have a significant impact on the environment. They are the main source of the urban heat island effect, and affect not only the energy balance, but also hydrology and carbon cycling, and both land and aquatic ecosystem services. In the last several decades, the pace of converting natural land surface to impervious surfaces has increased. Quantitatively monitoring the growth of impervious surface expansion and associated urbanization has become a priority topic across both the physical and social sciences. The recent availability of consistent, global scale data sets at 30m resolution such as the Global Land Survey from the Landsat satellites provides an unprecedented opportunity to map global impervious cover and urbanization at this resolution for the first time, with unprecedented detail and accuracy. Moreover, the spatial resolution of Landsat is absolutely essential to accurately resolve urban targets such a buildings, roads and parking lots. With long term GLS data now available for the 1975, 1990, 2000, 2005 and 2010 time periods, the land cover/use changes due to urbanization can now be quantified at this spatial scale as well. In the Global Land Survey - Imperviousness Mapping Project (GLS-IMP), we are producing the first global 30 m spatial resolution impervious cover data set. We have processed the GLS 2010 data set to surface reflectance (8500+ TM and ETM+ scenes) and are using a supervised classification method using a regression tree to produce continental scale impervious cover data sets. A very large set of accurate training samples is the key to the supervised classifications and is being derived through the interpretation of high spatial resolution (~2 m or less) commercial satellite data (Quickbird and Worldview2) available to us through the unclassified

  6. Spaceborne SAR data for global urban mapping at 30 m resolution using a robust urban extractor

    NASA Astrophysics Data System (ADS)

    Ban, Yifang; Jacob, Alexander; Gamba, Paolo

    2015-05-01

    With more than half of the world population now living in cities and 1.4 billion more people expected to move into cities by 2030, urban areas pose significant challenges on local, regional and global environment. Timely and accurate information on spatial distributions and temporal changes of urban areas are therefore needed to support sustainable development and environmental change research. The objective of this research is to evaluate spaceborne SAR data for improved global urban mapping using a robust processing chain, the KTH-Pavia Urban Extractor. The proposed processing chain includes urban extraction based on spatial indices and Grey Level Co-occurrence Matrix (GLCM) textures, an existing method and several improvements i.e., SAR data preprocessing, enhancement, and post-processing. ENVISAT Advanced Synthetic Aperture Radar (ASAR) C-VV data at 30 m resolution were selected over 10 global cities and a rural area from six continents to demonstrate the robustness of the improved method. The results show that the KTH-Pavia Urban Extractor is effective in extracting urban areas and small towns from ENVISAT ASAR data and built-up areas can be mapped at 30 m resolution with very good accuracy using only one or two SAR images. These findings indicate that operational global urban mapping is possible with spaceborne SAR data, especially with the launch of Sentinel-1 that provides SAR data with global coverage, operational reliability and quick data delivery.

  7. Estimating V̄s(30) (or NEHRP site classes) from shallow velocity models (depths < 30 m)

    USGS Publications Warehouse

    Boore, David M.

    2004-01-01

    The average velocity to 30 m [V??s(30)] is a widely used parameter for classifying sites to predict their potential to amplify seismic shaking. In many cases, however, models of shallow shear-wave velocities, from which V??s(30) can be computed, do not extend to 30 m. If the data for these cases are to be used, some method of extrapolating the velocities must be devised. Four methods for doing this are described here and are illustrated using data from 135 boreholes in California for which the velocity model extends to at least 30 m. Methods using correlations between shallow velocity and V??s(30) result in significantly less bias for shallow models than the simplest method of assuming that the lowermost velocity extends to 30 m. In addition, for all methods the percent of sites misclassified is generally less than 10% and falls to negligible values for velocity models extending to at least 25 m. Although the methods using correlations do a better job on average of estimating V??s(30), the simplest method will generally result in a lower value of V??s(30) and thus yield a more conservative estimate of ground motion [which generally increases as V??s(30) decreases].

  8. A global, 30-m resolution land-surface water body dataset for 2000

    NASA Astrophysics Data System (ADS)

    Feng, M.; Sexton, J. O.; Huang, C.; Song, D. X.; Song, X. P.; Channan, S.; Townshend, J. R.

    2014-12-01

    Inland surface water is essential to terrestrial ecosystems and human civilization. The distribution of surface water in space and its change over time are related to many agricultural, environmental and ecological issues, and are important factors that must be considered in human socioeconomic development. Accurate mapping of surface water is essential for both scientific research and policy-driven applications. Satellite-based remote sensing provides snapshots of Earth's surface and can be used as the main input for water mapping, especially in large areas. Global water areas have been mapped with coarse resolution remotely sensed data (e.g., the Moderate Resolution Imaging Spectroradiometer (MODIS)). However, most inland rivers and water bodies, as well as their changes, are too small to map at such coarse resolutions. Landsat TM (Thematic Mapper) and ETM+ (Enhanced Thematic Mapper Plus) imagery has a 30m spatial resolution and provides decades of records (~40 years). Since 2008, the opening of the Landsat archive, coupled with relatively lower costs associated with computing and data storage, has made comprehensive study of the dynamic changes of surface water over large even global areas more feasible. Although Landsat images have been used for regional and even global water mapping, the method can hardly be automated due to the difficulties on distinguishing inland surface water with variant degrees of impurities and mixing of soil background with only Landsat data. The spectral similarities to other land cover types, e.g., shadow and glacier remnants, also cause misidentification. We have developed a probabilistic based automatic approach for mapping inland surface water bodies. Landsat surface reflectance in multiple bands, derived water indices, and data from other sources are integrated to maximize the ability of identifying water without human interference. The approach has been implemented with open-source libraries to facilitate processing large

  9. Mapping irrigated areas of Ghana using fusion of 30 m and 250 m resolution remote-sensing data

    USGS Publications Warehouse

    Gumma, M.K.; Thenkabail, P.S.; Hideto, F.; Nelson, A.; Dheeravath, V.; Busia, D.; Rala, A.

    2011-01-01

    Maps of irrigated areas are essential for Ghana's agricultural development. The goal of this research was to map irrigated agricultural areas and explain methods and protocols using remote sensing. Landsat Enhanced Thematic Mapper (ETM+) data and time-series Moderate Resolution Imaging Spectroradiometer (MODIS) data were used to map irrigated agricultural areas as well as other land use/land cover (LULC) classes, for Ghana. Temporal variations in the normalized difference vegetation index (NDVI) pattern obtained in the LULC class were used to identify irrigated and non-irrigated areas. First, the temporal variations in NDVI pattern were found to be more consistent in long-duration irrigated crops than with short-duration rainfed crops due to more assured water supply for irrigated areas. Second, surface water availability for irrigated areas is dependent on shallow dug-wells (on river banks) and dug-outs (in river bottoms) that affect the timing of crop sowing and growth stages, which was in turn reflected in the seasonal NDVI pattern. A decision tree approach using Landsat 30 m one time data fusion with MODIS 250 m time-series data was adopted to classify, group, and label classes. Finally, classes were tested and verified using ground truth data and national statistics. Fuzzy classification accuracy assessment for the irrigated classes varied between 67 and 93%. An irrigated area derived from remote sensing (32,421 ha) was 20-57% higher than irrigated areas reported by Ghana's Irrigation Development Authority (GIDA). This was because of the uncertainties involved in factors such as: (a) absence of shallow irrigated area statistics in GIDA statistics, (b) non-clarity in the irrigated areas in its use, under-development, and potential for development in GIDA statistics, (c) errors of omissions and commissions in the remote sensing approach, and (d) comparison involving widely varying data types, methods, and approaches used in determining irrigated area statistics

  10. Global 30m Height Above the Nearest Drainage

    NASA Astrophysics Data System (ADS)

    Donchyts, Gennadii; Winsemius, Hessel; Schellekens, Jaap; Erickson, Tyler; Gao, Hongkai; Savenije, Hubert; van de Giesen, Nick

    2016-04-01

    Variability of the Earth surface is the primary characteristics affecting the flow of surface and subsurface water. Digital elevation models, usually represented as height maps above some well-defined vertical datum, are used a lot to compute hydrologic parameters such as local flow directions, drainage area, drainage network pattern, and many others. Usually, it requires a significant effort to derive these parameters at a global scale. One hydrological characteristic introduced in the last decade is Height Above the Nearest Drainage (HAND): a digital elevation model normalized using nearest drainage. This parameter has been shown to be useful for many hydrological and more general purpose applications, such as landscape hazard mapping, landform classification, remote sensing and rainfall-runoff modeling. One of the essential characteristics of HAND is its ability to capture heterogeneities in local environments, difficult to measure or model otherwise. While many applications of HAND were published in the academic literature, no studies analyze its variability on a global scale, especially, using higher resolution DEMs, such as the new, one arc-second (approximately 30m) resolution version of SRTM. In this work, we will present the first global version of HAND computed using a mosaic of two DEMS: 30m SRTM and Viewfinderpanorama DEM (90m). The lower resolution DEM was used to cover latitudes above 60 degrees north and below 56 degrees south where SRTM is not available. We compute HAND using the unmodified version of the input DEMs to ensure consistency with the original elevation model. We have parallelized processing by generating a homogenized, equal-area version of HydroBASINS catchments. The resulting catchment boundaries were used to perform processing using 30m resolution DEM. To compute HAND, a new version of D8 local drainage directions as well as flow accumulation were calculated. The latter was used to estimate river head by incorporating fixed and

  11. Reducing Uncertainties in Satellite-derived Forest Aboveground Biomass Estimates using a High Resolution Forest Cover Map

    NASA Astrophysics Data System (ADS)

    Zhang, G.; Ganguly, S.; Nemani, R. R.; Milesi, C.; Basu, S.; Kumar, U.

    2014-12-01

    Several studies to date have provided an extensive knowledge base for estimating forest aboveground biomass (AGB) and recent advances in space-based modeling of the 3-D canopy structure, combined with canopy reflectance measured by passive optical sensors and radar backscatter, are providing improved satellite-derived AGB density mapping for large scale carbon monitoring applications. A key limitation in forest AGB estimation from remote sensing, however, is the large uncertainty in forest cover estimates from the coarse-to-medium resolution satellite-derived land cover maps (present resolution is limited to 30-m of the USGS NLCD Program). The uncertainties in forest cover estimates at the Landsat scale result in high uncertainties for AGB estimation, predominantly in heterogeneous forest and urban landscapes. We have successfully developed an approach using a machine learning algorithm and High-Performance-Computing with NAIP air-borne imagery data for mapping tree cover at 1-m over California and Maryland. In a comparison with high resolution LiDAR data available over selected regions in the two states, we found our results to be promising both in terms of accuracy as well as our ability to scale nationally. The generated 1-m forest cover map will be aggregated to the Landsat spatial grid to demonstrate differences in AGB estimates (pixel-level AGB density, total AGB at aggregated scales like ecoregions and counties) when using a native 30-m forest cover map versus a 30-m map derived from a higher resolution dataset. The process will also be complemented with a LiDAR derived AGB estimate at the 30-m scale to aid in true validation.

  12. Influence of resolution in irrigated area mapping and area estimation

    USGS Publications Warehouse

    Velpuri, N.M.; Thenkabail, P.S.; Gumma, M.K.; Biradar, C.; Dheeravath, V.; Noojipady, P.; Yuanjie, L.

    2009-01-01

    The overarching goal of this paper was to determine how irrigated areas change with resolution (or scale) of imagery. Specific objectives investigated were to (a) map irrigated areas using four distinct spatial resolutions (or scales), (b) determine how irrigated areas change with resolutions, and (c) establish the causes of differences in resolution-based irrigated areas. The study was conducted in the very large Krishna River basin (India), which has a high degree of formal contiguous, and informal fragmented irrigated areas. The irrigated areas were mapped using satellite sensor data at four distinct resolutions: (a) NOAA AVHRR Pathfinder 10,000 m, (b) Terra MODIS 500 m, (c) Terra MODIS 250 m, and (d) Landsat ETM+ 30 m. The proportion of irrigated areas relative to Landsat 30 m derived irrigated areas (9.36 million hectares for the Krishna basin) were (a) 95 percent using MODIS 250 m, (b) 93 percent using MODIS 500 m, and (c) 86 percent using AVHRR 10,000 m. In this study, it was found that the precise location of the irrigated areas were better established using finer spatial resolution data. A strong relationship (R2 = 0.74 to 0.95) was observed between irrigated areas determined using various resolutions. This study proved the hypotheses that "the finer the spatial resolution of the sensor used, greater was the irrigated area derived," since at finer spatial resolutions, fragmented areas are detected better. Accuracies and errors were established consistently for three classes (surface water irrigated, ground water/conjunctive use irrigated, and nonirrigated) across the four resolutions mentioned above. The results showed that the Landsat data provided significantly higher overall accuracies (84 percent) when compared to MODIS 500 m (77 percent), MODIS 250 m (79 percent), and AVHRR 10,000 m (63 percent). ?? 2009 American Society for Photogrammetry and Remote Sensing.

  13. Analysis of DOA estimation spatial resolution using MUSIC algorithm

    NASA Astrophysics Data System (ADS)

    Guo, Yue; Wang, Hongyuan; Luo, Bin

    2005-11-01

    This paper presents a performance analysis of the spatial resolution of the direction of arrival (DOA) estimates attained by the multiple signal classification (MUSIC) algorithm for uncorrelated sources. The confidence interval of estimation angle which is much more intuitionistic will be considered as the new evaluation standard for the spatial resolution. Then, based on the statistic method, the qualitative analysis reveals the factors influencing the performance of the MUSIC algorithm. At last, quantitative simulations prove the theoretical analysis result exactly.

  14. Sediment delivery estimates in water quality models altered by resolution and source of topographic data.

    PubMed

    Beeson, Peter C; Sadeghi, Ali M; Lang, Megan W; Tomer, Mark D; Daughtry, Craig S T

    2014-01-01

    Moderate-resolution (30-m) digital elevation models (DEMs) are normally used to estimate slope for the parameterization of non-point source, process-based water quality models. These models, such as the Soil and Water Assessment Tool (SWAT), use the Universal Soil Loss Equation (USLE) and Modified USLE to estimate sediment loss. The slope length and steepness factor, a critical parameter in USLE, significantly affects sediment loss estimates. Depending on slope range, a twofold difference in slope estimation potentially results in as little as 50% change or as much as 250% change in the LS factor and subsequent sediment estimation. Recently, the availability of much finer-resolution (∼3 m) DEMs derived from Light Detection and Ranging (LiDAR) data has increased. However, the use of these data may not always be appropriate because slope values derived from fine spatial resolution DEMs are usually significantly higher than slopes derived from coarser DEMs. This increased slope results in considerable variability in modeled sediment output. This paper addresses the implications of parameterizing models using slope values calculated from DEMs with different spatial resolutions (90, 30, 10, and 3 m) and sources. Overall, we observed over a 2.5-fold increase in slope when using a 3-m instead of a 90-m DEM, which increased modeled soil loss using the USLE calculation by 130%. Care should be taken when using LiDAR-derived DEMs to parameterize water quality models because doing so can result in significantly higher slopes, which considerably alter modeled sediment loss.

  15. Estimating Carbon Storage and Sequestration by Urban Trees at Multiple Spatial Resolutions

    NASA Astrophysics Data System (ADS)

    Wu, J.; Tran, A.; Liao, A.

    2010-12-01

    Urban forests are an important component of urban-suburban environments. Urban trees provide not only a full range of social and psychological benefits to city dwellers, but also valuable ecosystem services to communities, such as removing atmospheric carbon dioxide, improving air quality, and reducing storm water runoff. There is an urgent need for developing strategic conservation plans for environmentally sustainable urban-suburban development based on the scientific understanding of the extent and function of urban forests. However, several challenges remain to accurately quantify various environmental benefits provided by urban trees, among which is to deal with the effect of changing spatial resolution and/or scale. In this study, we intended to examine the uncertainties of carbon storage and sequestration associated with the tree canopy coverage of different spatial resolutions. Multi-source satellite imagery data were acquired for the City of Fullerton, located in Orange County of California. The tree canopy coverage of the study area was classified at three spatial resolutions, ranging from 30 m (Landsat-5 Thematic Mapper), 15 m (Advanced Spaceborne Thermal Emission and Reflection Radiometer), to 2.5 m (QuickBird). We calculated the amount of carbon stored in the trees represented on the individual tree coverage maps and the annual carbon taken up by the trees with a model (i.e., CITYgreen) developed by the U.S. Forest Service. The results indicate that urban trees account for significant proportions of land cover in the study area even with the low spatial resolution data. The estimated carbon fixation benefits vary greatly depending on the details of land use and land cover classification. The extrapolation of estimation from the fine-resolution stand-level to the low-resolution landscape-scale will likely not preserve reasonable accuracy.

  16. Effect of spatial resolution on remote sensing estimation of total evaporation in the uMngeni catchment, South Africa

    NASA Astrophysics Data System (ADS)

    Shoko, Cletah; Clark, David; Mengistu, Michael; Dube, Timothy; Bulcock, Hartley

    2015-01-01

    This study evaluated the effect of two readily available multispectral sensors: the newly launched 30 m spatial resolution Landsat 8 and the long-serving 1000 m moderate resolution imaging spectroradiometer (MODIS) datasets in the spatial representation of total evaporation in the heterogeneous uMngeni catchment, South Africa, using the surface energy balance system model. The results showed that sensor spatial resolution plays a critical role in the accurate estimation of energy fluxes and total evaporation across a heterogeneous catchment. Landsat 8 estimates showed better spatial representation of the biophysical parameters and total evaporation for different land cover types, due to the relatively higher spatial resolution compared to the coarse spatial resolution MODIS sensor. Moreover, MODIS failed to capture the spatial variations of total evaporation estimates across the catchment. Analysis of variance (ANOVA) results showed that MODIS-based total evaporation estimates did not show any significant differences across different land cover types (one-way ANOVA; F1.924=1.412, p=0.186). However, Landsat 8 images yielded significantly different estimates between different land cover types (one-way ANOVA; F1.993=5.185, p<0.001). The validation results showed that Landsat 8 estimates were more comparable to eddy covariance (EC) measurements than the MODIS-based total evaporation estimates. EC measurement on May 23, 2013, was 3.8 mm/day, whereas the Landsat 8 estimate on the same day was 3.6 mm/day, with MODIS showing significantly lower estimates of 2.3 mm/day. The findings of this study underscore the importance of spatial resolution in estimating spatial variations of total evaporation at the catchment scale, thus, they provide critical information on the relevance of the readily available remote sensing products in water resources management in data-scarce environments.

  17. Spatial resolution estimation of LANDSAT-4 TM and MSS data

    NASA Technical Reports Server (NTRS)

    Mcgillem, C. D.; Anuta, P. E.; Yu, K. B.

    1983-01-01

    In order to verify that the LANDSAT-4 sensors are operating within specifications, it is useful to estimate the system parameters by analysis of the measured data. One parameter of particular interest is the sensor point-spread function (PSF) which determines the resolution of the system. A method of estimating the PSF is described that utilizes data obtained during scanning of ground elements having identifiable geometric and radiometric structure. These data are then processed in such a manner as to recover either the PSF itself or to estimate the parameters of an assumed functional representation of the PSF.

  18. Super-resolution without explicit subpixel motion estimation.

    PubMed

    Takeda, Hiroyuki; Milanfar, Peyman; Protter, Matan; Elad, Michael

    2009-09-01

    The need for precise (subpixel accuracy) motion estimates in conventional super-resolution has limited its applicability to only video sequences with relatively simple motions such as global translational or affine displacements. In this paper, we introduce a novel framework for adaptive enhancement and spatiotemporal upscaling of videos containing complex activities without explicit need for accurate motion estimation. Our approach is based on multidimensional kernel regression, where each pixel in the video sequence is approximated with a 3-D local (Taylor) series, capturing the essential local behavior of its spatiotemporal neighborhood. The coefficients of this series are estimated by solving a local weighted least-squares problem, where the weights are a function of the 3-D space-time orientation in the neighborhood. As this framework is fundamentally based upon the comparison of neighboring pixels in both space and time, it implicitly contains information about the local motion of the pixels across time, therefore rendering unnecessary an explicit computation of motions of modest size. The proposed approach not only significantly widens the applicability of super-resolution methods to a broad variety of video sequences containing complex motions, but also yields improved overall performance. Using several examples, we illustrate that the developed algorithm has super-resolution capabilities that provide improved optical resolution in the output, while being able to work on general input video with essentially arbitrary motion.

  19. Aggregation and Disaggregation Techniques Applied on Remotely Sensed Data to Obtain Optimum Resolution for Surface Energy Fluxes Estimation

    NASA Astrophysics Data System (ADS)

    Agam, N.; Kustas, W. P.; Li, F.; Anderson, M. C.

    2006-05-01

    Continuous monitoring of surface energy fluxes provides an important tool for precision agriculture management. It is, therefore, desirable to obtain these fluxes at agricultural field size (length scale ~ 10-100 m). To date, land surface temperature (LST), a fundamental input required for flux computations, is usually available at a nominal resolution of 1 km, which disables field-scale monitoring. Disaggregating LST data into field-scale sub-pixels was found to be possible, with deterioration in temperature accuracy as sub-pixel size is reduced. In contrast to LST, land use and fractional vegetation cover (LU and FC, additional key inputs) are available at high spatial resolution (e.g., 30 m). Aggregation of LU and FC to meet the lower resolution LST data introduces errors when aggregating to larger pixel sizes. The objective of this research is to find the optimum resolution that will minimize the errors due to aggregation of LU/FC and disaggregation of LST data, to provide continuous estimates of field scale surface energy fluxes. Data were used from the 2002 Soil Moisture-Atmosphere Coupling Experiment (SMACEX02) conducted over the upper Midwest corn and soybean production region of Iowa. Three dates during the period of rapid crops growth (June 23, July 1, and July 8) for which Landsat TM images are available were analyzed. The original pixels were aggregated to form 960 m pixels (to mimic thermal data currently available from MODIS) and were then disaggregated following the procedure suggested by Kustas et al. (2003)* to form 60, 120, and 240 m sub-pixels. LU and FC were obtained at 30 m resolution and then aggregated to 60, 120, 240, and 960 m. The Two-Source-Model was run at each of the resolutions using the pertinent inputs. The model output at 60 m resolution, using the original LST data was considered the base line, to which all other outputs were compared. For comparing the flux results at the lower resolutions, the 60 m flux output was aggregated. The

  20. Burn Severity Estimation Using MERIS Full Resolution Imagery

    NASA Astrophysics Data System (ADS)

    Oliva, Patricia; De Santis, Angela

    2010-12-01

    This paper presents the first results of Fire Effects Modelling and Mapping (FEMM) project carried out in the framemark of the Changing Earth Science Network. The objective of this study is to test the performance of the inversion of Radiative Transfer Models (RTMs) in ENVISA T-MERIS Full Resolution data to estimate burn severity levels in terms of Composite Burn Index (CBI) levels. Nevertheless, as the RTM model was calibrated in Landsat-TM images, evaluation of its performance in MERIS imagery was needed. We tested the performance of the RTM model in several study sites located in two large fires occurred in Spain during 2009 fire season. The results were validated by comparison with burn severity maps computed from Landsat-TM imagery. The results obtained showed values of the coefficient of determination of 0.92 and 0.95 thus, the estimation of burn severity was accurate and consistent, in spite of the different spatial and spectral resolutions.

  1. Estimating Agricultural Land Use Change in Karamoja, NE. Uganda Using Very High Resolution Satellite Data

    NASA Astrophysics Data System (ADS)

    Nakalembe, C. L.

    2013-12-01

    Land use information is useful for deriving biophysical variables for effective planning and management of natural resources. Land use information is also needed to understand negative environmental impacts of land use while maintaining economic and social benefits. Recent maps of land cover and land use have been generated for Africa at the continental scale from coarse resolution data (e.g. MODIS, Spot Vegetation, MERIS, and Landsat). In these map products, croplands and rangelands are generally poorly represented, particularly in semi-arid regions like Karamoja. Products derived from coarse resolution data also fail at mapping subsistence croplands and are limited in their use for extraction of land-cover specific temporal profiles for agricultural monitoring in the study area (Fritz, See, & Rembold, 2010). Given the subsistence nature of agriculture, most fields in Karamoja are very small that care not discernible from other land uses in coarse resolution data and data products such as FAO Africover2000. product derived from 30m Landsat data is one such product. There is a high level of disagreement and large errors of omission and omission due to the coarse resolution of the data used to derive the product. In addition population growth and policy changes in the region have resulted in a shift to agro-pastoralism and systematic expansion of cropland area since 2000. This research will produce an updated agricultural land use map for Karamoja. The land cover map will be used to estimate agricultural land use change in the region and as a filter to extract agricultural land use specific temporal profiles specific to agriculture to compare to crop statistics.

  2. High Spatio-Temporal Resolution Bathymetry Estimation and Morphology

    NASA Astrophysics Data System (ADS)

    Bergsma, E. W. J.; Conley, D. C.; Davidson, M. A.; O'Hare, T. J.

    2015-12-01

    In recent years, bathymetry estimates using video images have become increasingly accurate. With the cBathy code (Holman et al., 2013) fully operational, bathymetry results with 0.5 metres accuracy have been regularly obtained at Duck, USA. cBathy is based on observations of the dominant frequencies and wavelengths of surface wave motions and estimates the depth (and hence allows inference of bathymetry profiles) based on linear wave theory. Despite the good performance at Duck, large discrepancies were found related to tidal elevation and camera height (Bergsma et al., 2014) and on the camera boundaries. A tide dependent floating pixel and camera boundary solution have been proposed to overcome these issues (Bergsma et al., under review). The video-data collection is set estimate depths hourly on a grid with resolution in the order of 10x25 meters. Here, the application of the cBathy at Porthtowan in the South-West of England is presented. Hourly depth estimates are combined and analysed over a period of 1.5 years (2013-2014). In this work the focus is on the sub-tidal region, where the best cBathy results are achieved. The morphology of the sub-tidal bar is tracked with high spatio-temporal resolution on short and longer time scales. Furthermore, the impact of the storm and reset (sudden and large changes in bathymetry) of the sub-tidal area is clearly captured with the depth estimations. This application shows that the high spatio-temporal resolution of cBathy makes it a powerful tool for coastal research and coastal zone management.

  3. Breast density estimation from high spectral and spatial resolution MRI.

    PubMed

    Li, Hui; Weiss, William A; Medved, Milica; Abe, Hiroyuki; Newstead, Gillian M; Karczmar, Gregory S; Giger, Maryellen L

    2016-10-01

    A three-dimensional breast density estimation method is presented for high spectral and spatial resolution (HiSS) MR imaging. Twenty-two patients were recruited (under an Institutional Review Board--approved Health Insurance Portability and Accountability Act-compliant protocol) for high-risk breast cancer screening. Each patient received standard-of-care clinical digital x-ray mammograms and MR scans, as well as HiSS scans. The algorithm for breast density estimation includes breast mask generating, breast skin removal, and breast percentage density calculation. The inter- and intra-user variabilities of the HiSS-based density estimation were determined using correlation analysis and limits of agreement. Correlation analysis was also performed between the HiSS-based density estimation and radiologists' breast imaging-reporting and data system (BI-RADS) density ratings. A correlation coefficient of 0.91 ([Formula: see text]) was obtained between left and right breast density estimations. An interclass correlation coefficient of 0.99 ([Formula: see text]) indicated high reliability for the inter-user variability of the HiSS-based breast density estimations. A moderate correlation coefficient of 0.55 ([Formula: see text]) was observed between HiSS-based breast density estimations and radiologists' BI-RADS. In summary, an objective density estimation method using HiSS spectral data from breast MRI was developed. The high reproducibility with low inter- and low intra-user variabilities shown in this preliminary study suggest that such a HiSS-based density metric may be potentially beneficial in programs requiring breast density such as in breast cancer risk assessment and monitoring effects of therapy.

  4. Estimation of vegetation cover at subpixel resolution using LANDSAT data

    NASA Technical Reports Server (NTRS)

    Jasinski, Michael F.; Eagleson, Peter S.

    1986-01-01

    The present report summarizes the various approaches relevant to estimating canopy cover at subpixel resolution. The approaches are based on physical models of radiative transfer in non-homogeneous canopies and on empirical methods. The effects of vegetation shadows and topography are examined. Simple versions of the model are tested, using the Taos, New Mexico Study Area database. Emphasis has been placed on using relatively simple models requiring only one or two bands. Although most methods require some degree of ground truth, a two-band method is investigated whereby the percent cover can be estimated without ground truth by examining the limits of the data space. Future work is proposed which will incorporate additional surface parameters into the canopy cover algorithm, such as topography, leaf area, or shadows. The method involves deriving a probability density function for the percent canopy cover based on the joint probability density function of the observed radiances.

  5. Estimating stellar wind parameters from low-resolution magnetograms

    NASA Astrophysics Data System (ADS)

    Jardine, M.; Vidotto, A. A.; See, V.

    2017-02-01

    Stellar winds govern the angular momentum evolution of solar-like stars throughout their main-sequence lifetime. The efficiency of this process depends on the geometry of the star's magnetic field. There has been a rapid increase recently in the number of stars for which this geometry can be determined through spectropolarimetry. We present a computationally efficient method to determine the 3D geometry of the stellar wind and to estimate the mass-loss rate and angular momentum loss rate based on these observations. Using solar magnetograms as examples, we quantify the extent to which the values obtained are affected by the limited spatial resolution of stellar observations. We find that for a typical stellar surface resolution of 20o-30o, predicted wind speeds are within 5 per cent of the value at full resolution. Mass-loss rates and angular momentum loss rates are within 5-20 per cent. In contrast, the predicted X-ray emission measures can be underestimated by one-to-two orders of magnitude, and their rotational modulations by 10-20 per cent.

  6. An efficient selective perceptual-based super-resolution estimator.

    PubMed

    Karam, Lina J; Sadaka, Nabil G; Ferzli, Rony; Ivanovski, Zoran A

    2011-12-01

    In this paper, a selective perceptual-based (SELP) framework is presented to reduce the complexity of popular super-resolution (SR) algorithms while maintaining the desired quality of the enhanced images/video. A perceptual human visual system model is proposed to compute local contrast sensitivity thresholds. The obtained thresholds are used to select which pixels are super-resolved based on the perceived visibility of local edges. Processing only a set of perceptually significant pixels reduces significantly the computational complexity of SR algorithms without losing the achievable visual quality. The proposed SELP framework is integrated into a maximum-a posteriori-based SR algorithm as well as a fast two-stage fusion-restoration SR estimator. Simulation results show a significant reduction on average in computational complexity with comparable signal-to-noise ratio gains and visual quality.

  7. Improved PPP ambiguity resolution by COES FCB estimation

    NASA Astrophysics Data System (ADS)

    Li, Yihe; Gao, Yang; Shi, Junbo

    2016-05-01

    Precise point positioning (PPP) integer ambiguity resolution is able to significantly improve the positioning accuracy with the correction of fractional cycle biases (FCBs) by shortening the time to first fix (TTFF) of ambiguities. When satellite orbit products are adopted to estimate the satellite FCB corrections, the narrow-lane (NL) FCB corrections will be contaminated by the orbit's line-of-sight (LOS) errors which subsequently affect ambiguity resolution (AR) performance, as well as positioning accuracy. To effectively separate orbit errors from satellite FCBs, we propose a cascaded orbit error separation (COES) method for the PPP implementation. Instead of using only one direction-independent component in previous studies, the satellite NL improved FCB corrections are modeled by one direction-independent component and three directional-dependent components per satellite in this study. More specifically, the direction-independent component assimilates actual FCBs, whereas the directional-dependent components are used to assimilate the orbit errors. To evaluate the performance of the proposed method, GPS measurements from a regional and a global network are processed with the IGSReal-time service (RTS), IGS rapid (IGR) products and predicted orbits with >10 cm 3D root mean square (RMS) error. The improvements by the proposed FCB estimation method are validated in terms of ambiguity fractions after applying FCB corrections and positioning accuracy. The numerical results confirm that the obtained FCBs using the proposed method outperform those by conventional method. The RMS of ambiguity fractions after applying FCB corrections is reduced by 13.2 %. The position RMSs in north, east and up directions are reduced by 30.0, 32.0 and 22.0 % on average.

  8. Landsat-derived Patterns of Snow Covered Area (SCA) and the Potential for Enhancing the Spatial Resolution of MODIS-derived SCA Estimates

    NASA Astrophysics Data System (ADS)

    Selkowitz, D.

    2011-12-01

    Seasonal snow cover is dynamic and exhibits a high degree of spatial and temporal heterogeneity, making remote sensing a key component of any successful snow cover monitoring strategy. While the availability of daily snow covered area (SCA) extent at 500 m spatial resolution from MODIS represents a major leap forward for snow cover monitoring, many applications require or would benefit from snow cover data available at a finer spatial resolution. The Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM+) instruments are suitable for SCA mapping and can provide SCA maps at 30 m spatial resolution from 1984 to present. With the opening of the Landsat archive, all scenes acquired by the TM and ETM+ sensors are now available at no cost, with more than 800 scenes available for many locations in the conterminous United States. The nearly 30 years of TM and ETM+ imagery can be used to identify landscape snow cover patterns, the degree of interannual consistency of these patterns, and can ultimately help illuminate the complex processes responsible for these patterns. However, the 16-day return interval of Landsat is typically insufficient to capture the inter- and intra-annual evolution of SCA on the landscape. While the timing of the seasonal evolution of fine to medium resolution SCA patterns may vary substantially from year to year, for many regions, the spatial distribution of SCA patterns remains consistent across most years. As a result, it may be possible to exploit the information contained in multiple years of Landsat SCA patterns to enhance the spatial resolution of existing moderate resolution SCA products such as those available from MODIS. In this study, Landsat TM and ETM+ data from path 42, row 34 (covering a 185 km x 175 km area in the central Sierra Nevada mountains of California) are used to develop 30 m snow cover relative probability distributions for 500 m MODIS-like grid cells. We demonstrate that these relative probability distributions

  9. Apparent diffusion profile estimation from high angular resolution diffusion images

    NASA Astrophysics Data System (ADS)

    Descoteaux, Maxime; Angelino, Elaine; Fitzgibbons, Shaun; Deriche, Rachid

    2006-03-01

    High angular resolution diffusion imaging (HARDI) has recently been of great interest to characterize non-Gaussian diffusion process. In the white matter of the brain, this occurs when fiber bundles cross, kiss or diverge within the same voxel. One of the important goal is to better describe the apparent diffusion process in these multiple fiber regions, thus overcoming the limitations of classical diffusion tensor imaging (DTI). In this paper, we design the appropriate mathematical tools to describe noisy HARDI data. Using a meaningful modified spherical harmonics basis to capture the physical constraints of the problem, we propose a new regularization algorithm to estimate a smoother and closer diffusivity profile to the true diffusivities without noise. We exploit properties of the spherical harmonics to define a smoothing term based on the Laplace-Beltrami for functions defined on the unit sphere. An additional contribution of the paper is the derivation of the general transformation taking the spherical harmonics coefficients to the high order tensor independent elements. This allows the careful study of the state of the art high order anisotropy measures computed from either spherical harmonics or tensor coefficients. We analyze their ability to characterize the underlying diffusion process. We are able to recover voxels with isotropic, single fiber anisotropic and multiple fiber anisotropic diffusion. We test and validate the approach on diffusion profiles from synthetic data and from a biological rat phantom.

  10. Using multi-satellite data fusion to estimate daily high spatial resolution evapotranspiration over a forested site in North Carolina

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Atmosphere-Land Exchange Inverse model and associated disaggregation scheme (ALEXI/DisALEXI). Satellite-based ET retrievals from both the Moderate Resolution Imaging Spectoradiometer (MODIS; 1km, daily) and Landsat (30m, bi-weekly) are fused with The Spatial and Temporal Adaptive Reflective Fusion ...

  11. A self-trained classification technique for producing 30 m percent-water maps from Landsat data

    USGS Publications Warehouse

    Rover, Jennifer R.; Wylie, Bruce K.; Ji, Lei

    2010-01-01

    Small bodies of water can be mapped with moderate-resolution satellite data using methods where water is mapped as subpixel fractions using field measurements or high-resolution images as training datasets. A new method, developed from a regression-tree technique, uses a 30 m Landsat image for training the regression tree that, in turn, is applied to the same image to map subpixel water. The self-trained method was evaluated by comparing the percent-water map with three other maps generated from established percent-water mapping methods: (1) a regression-tree model trained with a 5 m SPOT 5 image, (2) a regression-tree model based on endmembers and (3) a linear unmixing classification technique. The results suggest that subpixel water fractions can be accurately estimated when high-resolution satellite data or intensively interpreted training datasets are not available, which increases our ability to map small water bodies or small changes in lake size at a regional scale.

  12. An Algorithm for the Retrieval of 30-m Snow-Free Albedo from Landsat Surface Reflectance and MODIS BRDF

    NASA Technical Reports Server (NTRS)

    Shuai, Yanmin; Masek, Jeffrey G.; Gao, Feng; Schaaf, Crystal B.

    2011-01-01

    We present a new methodology to generate 30-m resolution land surface albedo using Landsat surface reflectance and anisotropy information from concurrent MODIS 500-m observations. Albedo information at fine spatial resolution is particularly useful for quantifying climate impacts associated with land use change and ecosystem disturbance. The derived white-sky and black-sky spectral albedos maybe used to estimate actual spectral albedos by taking into account the proportion of direct and diffuse solar radiation arriving at the ground. A further spectral-to-broadband conversion based on extensive radiative transfer simulations is applied to produce the broadband albedos at visible, near infrared, and shortwave regimes. The accuracy of this approach has been evaluated using 270 Landsat scenes covering six field stations supported by the SURFace RADiation Budget Network (SURFRAD) and Atmospheric Radiation Measurement Southern Great Plains (ARM/SGP) network. Comparison with field measurements shows that Landsat 30-m snow-free shortwave albedos from all seasons generally achieve an absolute accuracy of +/-0.02 - 0.05 for these validation sites during available clear days in 2003-2005,with a root mean square error less than 0.03 and a bias less than 0.02. This level of accuracy has been regarded as sufficient for driving global and regional climate models. The Landsat-based retrievals have also been compared to the operational 16-day MODIS albedo produced every 8-days from MODIS on Terra and Aqua (MCD43A). The Landsat albedo provides more detailed landscape texture, and achieves better agreement (correlation and dynamic range) with in-situ data at the validation stations, particularly when the stations include a heterogeneous mix of surface covers.

  13. On high-resolution image estimation using low-resolution brain MRI.

    PubMed

    Rousseau, François; Gounot, Daniel; Studholme, Colin

    2013-01-01

    In the context of medical imaging, super-resolution (SR) is currently a promising post-processing technique to increase the image resolution. However, although many SR methods have been proposed in the literature, the gain of this type of approach in a real situation has not been precisely quantified. In this work, we evaluate image acquisition protocols and SR algorithms using in-vivo brain MR data as gold standard. The results show that using orthogonal image acquisition protocols lead to better reconstructed images than overlapping parallel low-resolution image stacks. Moreover, if the preprocessing steps (such as image denoising and intensity correction) are carefully performed, there is no significant differences between the evaluated SR algorithms.

  14. Selecting a spatial resolution for estimation of per-field green leaf area index

    NASA Technical Reports Server (NTRS)

    Curran, Paul J.; Williamson, H. Dawn

    1988-01-01

    For any application of multispectral scanner (MSS) data, a user is faced with a number of choices concerning the characteristics of the data; one of these is their spatial resolution. A pilot study was undertaken to determine the spatial resolution that would be optimal for the per-field estimation of green leaf area index (GLAI) in grassland. By reference to empirically-derived data from three areas of grassland, the suitable spatial resolution was hypothesized to lie in the lower portion of a 2-18 m range. To estimate per-field GLAI, airborne MSS data were collected at spatial resolutions of 2 m, 5 m and 10 m. The highest accuracies of per-field GLAI estimation were achieved using MSS data with spatial resolutions of 2 m and 5 m.

  15. High Resolution Temperature Estimation During Laser Cladding of Stainless Steel

    NASA Astrophysics Data System (ADS)

    Devesse, Wim; De Baere, Dieter; Hinderdael, Michaël; Guillaume, Patrick

    Laser cladding is a technique that is used for the coating, repair and production of metallic parts. Material is added to the surface of the part by injecting a flow of powder into a melt pool that is created with a high power laser beam. When the beam scans the surface of the substrate, strong local heating and cooling results. A good knowledge of the temperature distribution history during the laser cladding process is vital to predict and optimize the material properties of the final part. This paper presents a contactless temperature measurement system with high temporal and spatial resolution based on a hyperspectral line camera. High temperature measurements were made during laser cladding of AISI 316L stainless steel. A good correlation is shown between the temperature measurements and microscope images taken after creation of the clad.

  16. Interferometric 30 m bench for calibrations of 1D scales and optical distance measuring instruments

    NASA Astrophysics Data System (ADS)

    Unkuri, J.; Rantanen, A.; Manninen, J.; Esala, V.-P.; Lassila, A.

    2012-09-01

    During construction of a new metrology building for MIKES, a 30 m interferometric bench was designed. The objective was to implement a straight, stable, adjustable and multifunctional 30 m measuring bench for calibrations. Special attention was paid to eliminating the effects of thermal expansion and inevitable concrete shrinkage. The linear guide, situated on top of a monolithic concrete beam, comprises two parallel round shafts with adjustable fixtures every 1 m. A carriage is moved along the rail and its position is followed by a reference interferometer. Depending on the measurement task, one or two retro-reflectors are fixed on the carriage. A microscope with a CCD camera and a monitor can be used to detect line mark positions on different line standards. When calibrating optical distance measuring instruments, various targets can be fixed to the carriage. For the most accurate measurements an online Abbe-error correction based on simultaneous carriage pitch measurement by a separate laser interferometer is applied. The bench is used for calibrations of machinist scales, tapes, circometers, electronic distance meters, total stations and laser trackers. The estimated expanded uncertainty for 30 m displacement for highest accuracy calibrations is 2.6 µm.

  17. Spatiotemporal downscaling approaches for monitoring 8-day 30 m actual evapotranspiration

    NASA Astrophysics Data System (ADS)

    Ke, Yinghai; Im, Jungho; Park, Seonyoung; Gong, Huili

    2017-04-01

    Continuous monitoring of actual evapotranspiration (ET) is critical for water resources management at both regional and local scales. Although the MODIS ET product (MOD16A2) provides viable sources for ET monitoring at 8-day intervals, the spatial resolution (1 km) is too coarse for local scale applications. In this study, we propose a machine learning and spatial temporal fusion (STF)-integrated approach in order to generate 8-day 30 m ET based on both MOD16A2 and Landsat 8 data with three schemes. Random forest machine learning was used to downscale MODIS 1 km ET to 30 m resolution based on nine Landsat-derived indicators including vegetation indices (VIs) and land surface temperature (LST). STF-based models including Spatial and Temporal Adaptive Reflectance Fusion Model and Spatio-Temporal Image Fusion Model were used to derive synthetic Landsat surface reflectance (scheme 1)/VIs (scheme 2)/ET (scheme 3) on Landsat-unavailable dates. The approach was tested over two study sites in the United States. The results showed that fusion of Landsat VIs produced the best accuracy of predicted ET (R2 = 0.52-0.97, RMSE = 0.47-3.0 mm/8 days and rRMSE = 6.4-37%). High density of cloud-clear Landsat image acquisitions and low spatial heterogeneity of Landsat VIs benefit the ET prediction. The downscaled 30 m ET had good agreement with MODIS ET (RMSE = 0.42-3.4 mm/8 days, rRMSE = 3.2-26%). Comparison with the in situ ET measurements showed that the downscaled ET had higher accuracy than MODIS ET.

  18. Three-dimensional super-resolution structured illumination microscopy with maximum a posteriori probability image estimation.

    PubMed

    Lukeš, Tomáš; Křížek, Pavel; Švindrych, Zdeněk; Benda, Jakub; Ovesný, Martin; Fliegel, Karel; Klíma, Miloš; Hagen, Guy M

    2014-12-01

    We introduce and demonstrate a new high performance image reconstruction method for super-resolution structured illumination microscopy based on maximum a posteriori probability estimation (MAP-SIM). Imaging performance is demonstrated on a variety of fluorescent samples of different thickness, labeling density and noise levels. The method provides good suppression of out of focus light, improves spatial resolution, and allows reconstruction of both 2D and 3D images of cells even in the case of weak signals. The method can be used to process both optical sectioning and super-resolution structured illumination microscopy data to create high quality super-resolution images.

  19. Experimental results of a 30 m, 3-core HTSC cable

    NASA Astrophysics Data System (ADS)

    Masuda, Takato; Kato, Takeshi; Yumura, Hiroyasu; Hirose, Masayuki; Isojima, Shigeki; Honjo, Shoichi; Matsuo, Kimiyoshi; Mimura, Tomoo; Takahashi, Yoshihisa

    2002-08-01

    A high temperature superconducting (HTSC) cable is expected to transport large electric power with a compact size because of its high critical current density. We have been developing a 3-core 66 kV class HTSC cable, which is applied to the ∅150 mm duct, and is composed of a conductor and a shield wound with Ag-Mn sheathed Bi-2223 tapes, electrical insulation with polypropylene laminated paper impregnated with liquid nitrogen and thermal insulation with co-axial corrugated pipes. A 30 m, 3-core cable system has been constructed to verify the 3-core performance after its production, laying and cooling. The cable had good performance to mechanical stress in the factory process. The critical current of the cable was more than 2.4 kA at 77 K. The AC loss of the conductor part was 0.5 W/m/phase at 1 kA rms, which agreed well with the calculated value of the spiral pitch adjustment technique. A 130 kV rms AC was successfully applied without any change in tan δ and capacitance. As a next step, a 100 m HTSC cable has been designed and developed based on these experimental results.

  20. Cherenkov telescopes as optical telescopes for bright sources: today's specialized 30-m telescopes?

    NASA Astrophysics Data System (ADS)

    Lacki, Brian C.

    2011-10-01

    Imaging Atmospheric Cherenkov Telescopes (IACTs) use large-aperture (3-30 m) optical telescopes with arcminute angular resolution to detect TeV gamma-rays in the atmosphere. I show that IACTs are well suited for optical observations of bright sources (V≲ 8-10), because these sources are brighter than the sky background. Their advantages are especially great on rapid time-scales. Thus, IACTs might study many phenomena optically, including transiting exoplanets and the brightest gamma-ray bursts. In principle, an IACT could achieve millimagnitude photometry of these objects with second-long exposures. I also consider the potential for optical spectroscopy with IACTs, finding that their poor angular resolution limits their usefulness for high spectral resolutions, unless complex instruments are developed. The high photon collection rate of IACTs is potentially useful for precise polarimetry. Finally, I briefly discuss the broader possibilities of extremely large, low-resolution telescopes, including a 10 arcsec resolution telescope and space-borne telescopes.

  1. The millimeter IRAM-30 m line survey toward IK Tauri

    NASA Astrophysics Data System (ADS)

    Velilla Prieto, L.; Sánchez Contreras, C.; Cernicharo, J.; Agúndez, M.; Quintana-Lacaci, G.; Bujarrabal, V.; Alcolea, J.; Balança, C.; Herpin, F.; Menten, K. M.; Wyrowski, F.

    2017-01-01

    Aims: We aim to investigate the physical and chemical properties of the molecular envelope of the oxygen-rich AGB star IK Tau. Methods: We carried out a millimeter wavelength line survey between 79 and 356 GHz with the IRAM-30 m telescope. We analysed the molecular lines detected in IK Tau using the population diagram technique to derive rotational temperatures and column densities. We conducted a radiative transfer analysis of the SO2 lines, which also helped us to verify the validity of the approximated method of the population diagram for the rest of the molecules. Results: For the first time in this source we detected rotational lines in the ground vibrational state of HCO+, NS, NO, and H2CO, as well as several isotopologues of molecules previously identified, namely, C18O, Si17O, Si18O, 29SiS, 30SiS, Si34S, H13CN, 13CS, C34S, H234S, 34SO, and 34SO2. We also detected several rotational lines in vibrationally excited states of SiS and SiO isotopologues, as well as rotational lines of H2O in the vibrationally excited state ν2 = 2. We have also increased the number of rotational lines detected of molecules that were previously identified toward IK Tau, including vibrationally excited states, enabling a detailed study of the molecular abundances and excitation temperatures. In particular, we highlight the detection of NS and H2CO with fractional abundances of f(NS) 10-8 and f(H2CO) [10-7-10-8]. Most of the molecules display rotational temperatures between 15 and 40 K. NaCl and SiS isotopologues display rotational temperatures higher than the average ( 65 K). In the case of SO2 a warm component with Trot 290 K is also detected. Conclusions: With a total of 350 lines detected of 34 different molecular species (including different isotopologues), IK Tau displays a rich chemistry for an oxygen-rich circumstellar envelope. The detection of carbon bearing molecules like H2CO, as well as the discrepancies found between our derived abundances and the predictions from

  2. Estimation of high-resolution dust column density maps. Empirical model fits

    NASA Astrophysics Data System (ADS)

    Juvela, M.; Montillaud, J.

    2013-09-01

    Context. Sub-millimetre dust emission is an important tracer of column density N of dense interstellar clouds. One has to combine surface brightness information at different spatial resolutions, and specific methods are needed to derive N at a resolution higher than the lowest resolution of the observations. Some methods have been discussed in the literature, including a method (in the following, method B) that constructs the N estimate in stages, where the smallest spatial scales being derived only use the shortest wavelength maps. Aims: We propose simple model fitting as a flexible way to estimate high-resolution column density maps. Our goal is to evaluate the accuracy of this procedure and to determine whether it is a viable alternative for making these maps. Methods: The new method consists of model maps of column density (or intensity at a reference wavelength) and colour temperature. The model is fitted using Markov chain Monte Carlo methods, comparing model predictions with observations at their native resolution. We analyse simulated surface brightness maps and compare its accuracy with method B and the results that would be obtained using high-resolution observations without noise. Results: The new method is able to produce reliable column density estimates at a resolution significantly higher than the lowest resolution of the input maps. Compared to method B, it is relatively resilient against the effects of noise. The method is computationally more demanding, but is feasible even in the analysis of large Herschel maps. Conclusions: The proposed empirical modelling method E is demonstrated to be a good alternative for calculating high-resolution column density maps, even with considerable super-resolution. Both methods E and B include the potential for further improvements, e.g., in the form of better a priori constraints.

  3. Crop area estimation using high and medium resolution satellite imagery in areas with complex topography

    NASA Astrophysics Data System (ADS)

    Husak, G. J.; Marshall, M. T.; Michaelsen, J.; Pedreros, D.; Funk, C.; Galu, G.

    2008-07-01

    Reliable estimates of cropped area (CA) in developing countries with chronic food shortages are essential for emergency relief and the design of appropriate market-based food security programs. Satellite interpretation of CA is an effective alternative to extensive and costly field surveys, which fail to represent the spatial heterogeneity at the country-level. Bias-corrected, texture based classifications show little deviation from actual crop inventories, when estimates derived from aerial photographs or field measurements are used to remove systematic errors in medium resolution estimates. In this paper, we demonstrate a hybrid high-medium resolution technique for Central Ethiopia that combines spatially limited unbiased estimates from IKONOS images, with spatially extensive Landsat ETM+ interpretations, land-cover, and SRTM-based topography. Logistic regression is used to derive the probability of a location being crop. These individual points are then aggregated to produce regional estimates of CA. District-level analysis of Landsat based estimates showed CA totals which supported the estimates of the Bureau of Agriculture and Rural Development. Continued work will evaluate the technique in other parts of Africa, while segmentation algorithms will be evaluated, in order to automate classification of medium resolution imagery for routine CA estimation in the future.

  4. Crop area estimation using high and medium resolution satellite imagery in areas with complex topography

    USGS Publications Warehouse

    Husak, G.J.; Marshall, M. T.; Michaelsen, J.; Pedreros, Diego; Funk, Christopher C.; Galu, G.

    2008-01-01

    Reliable estimates of cropped area (CA) in developing countries with chronic food shortages are essential for emergency relief and the design of appropriate market-based food security programs. Satellite interpretation of CA is an effective alternative to extensive and costly field surveys, which fail to represent the spatial heterogeneity at the country-level. Bias-corrected, texture based classifications show little deviation from actual crop inventories, when estimates derived from aerial photographs or field measurements are used to remove systematic errors in medium resolution estimates. In this paper, we demonstrate a hybrid high-medium resolution technique for Central Ethiopia that combines spatially limited unbiased estimates from IKONOS images, with spatially extensive Landsat ETM+ interpretations, land-cover, and SRTM-based topography. Logistic regression is used to derive the probability of a location being crop. These individual points are then aggregated to produce regional estimates of CA. District-level analysis of Landsat based estimates showed CA totals which supported the estimates of the Bureau of Agriculture and Rural Development. Continued work will evaluate the technique in other parts of Africa, while segmentation algorithms will be evaluated, in order to automate classification of medium resolution imagery for routine CA estimation in the future.

  5. Application of high-resolution, remotely sensed data for transient storage modeling parameter estimation

    NASA Astrophysics Data System (ADS)

    Bingham, Q. G.; Neilson, B. T.; Neale, C. M. U.; Cardenas, M. B.

    2012-08-01

    This paper presents a method that uses high-resolution multispectral and thermal infrared imagery from airborne remote sensing for estimating two model parameters within the two-zone in-stream temperature and solute (TZTS) model. Previous TZTS modeling efforts have provided accurate in-stream temperature predictions; however, model parameter ranges resulting from the multiobjective calibrations were quite large. In addition to the data types previously required to populate and calibrate the TZTS model, high-resolution, remotely sensed thermal infrared (TIR) and near-infrared, red, and green (multispectral) band imagery were collected to help estimate two previously calibrated parameters: (1) average total channel width (BTOT) and (2) the fraction of the channel comprising surface transient storage zones (β). Multispectral imagery in combination with the TIR imagery provided high-resolution estimates ofBTOT. In-stream temperature distributions provided by the TIR imagery enabled the calculation of temperature thresholds at which main channel temperatures could be delineated from surface transient storage, permitting the estimation ofβ. It was found that an increase in the resolution and frequency at which BTOT and β were physically estimated resulted in similar objective functions in the main channel and transient storage zones, but the uncertainty associated with the estimated parameters decreased.

  6. Resolution and Smoothing Effect of Tomogram and Their Impact on Computational Velocity Estimation

    NASA Astrophysics Data System (ADS)

    Song, D.; Keehm, Y.

    2008-12-01

    Pore microstructure and pore-scale simulations have been used to understand physical properties of rocks and their interrelations. Pore microstructures are typically obtained from the X-ray tomographic technique, and we can obtain up to one micron spatial resolution from high-resolution scanning facilities. Though the accuracy of pore-scale simulations depends on grain size distribution, transport properties (permeability and electrical conductivity) can be accurately estimated with current spatial resolution and are recently used widely in many applications. However, the elastic properties can be problematic, because they are sensitive to grain contact areas, which are very difficult to resolve accurately by tomography. In this paper, we are presenting results on the effect of resolution and smoothing of tomogram on pore-scale velocity calculation. We used three different rocks: 17%-porosity sandstone from offshore Korea; 23%-porosity Aztec sandstone; and 42%-porosity beach sand. Three dimensional microstructures were obtained from different high-resolution scan facilities with different resolutions. We found that the resolution of tomogram highly affect velocity estimation from FEM elastic simulation. Two-micron spatial resolution is sometimes not enough to resolve the contact areas between 200-micron grains. Especially for high porosity sandstone, the calculated velocity was overestimated by tens of percent. In addition, smoothing effect from image processing on tomogram acquisition can cause non-negligible velocity overestimation; however, this effect is smaller than that from resolution and can be corrected by anti-smoothing filtering techniques. In conclusion, care should be taken to estimate the velocity of unconsolidated or high-porosity sandstone from pore-scale simulation and smoothing effect is also investigated more carefully.

  7. BOREAS TE-18, 30-m, Radiometrically Rectified Landsat TM Imagery

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Knapp, David

    2000-01-01

    The BOREAS TE-18 team used a radiometric rectification process to produce standardized DN values for a series of Landsat TM images of the BOREAS SSA and NSA in order to compare images that were collected under different atmospheric conditions. The images for each study area were referenced to an image that had very clear atmospheric qualities. The reference image for the SSA was collected on 02-Sep-1994, while the reference image for the NSA was collected on 21-Jun-1995. the 23 rectified images cover the period of 07-Jul-1985 to 18 Sep-1994 in the SSA and from 22-Jun-1984 to 09-Jun-1994 in the NSA. Each of the reference scenes had coincident atmospheric optical thickness measurements made by RSS-11. The radiometric rectification process is described in more detail by Hall et al. (199 1). The original Landsat TM data were received from CCRS for use in the BOREAS project. The data are stored in binary image-format files. Due to the nature of the radiometric rectification process and copyright issues, these full-resolution images may not be publicly distributed. However, a spatially degraded 60-m resolution version of the images is available on the BOREAS CD-ROM series. See Sections 15 and 16 for information about how to possibly acquire the full resolution data. Information about the full-resolution images is provided in an inventory listing on the CD-ROMs. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Activity Archive Center (DAAC).

  8. Estimating the resolution limit of the map equation in community detection

    NASA Astrophysics Data System (ADS)

    Kawamoto, Tatsuro; Rosvall, Martin

    2015-01-01

    A community detection algorithm is considered to have a resolution limit if the scale of the smallest modules that can be resolved depends on the size of the analyzed subnetwork. The resolution limit is known to prevent some community detection algorithms from accurately identifying the modular structure of a network. In fact, any global objective function for measuring the quality of a two-level assignment of nodes into modules must have some sort of resolution limit or an external resolution parameter. However, it is yet unknown how the resolution limit affects the so-called map equation, which is known to be an efficient objective function for community detection. We derive an analytical estimate and conclude that the resolution limit of the map equation is set by the total number of links between modules instead of the total number of links in the full network as for modularity. This mechanism makes the resolution limit much less restrictive for the map equation than for modularity; in practice, it is orders of magnitudes smaller. Furthermore, we argue that the effect of the resolution limit often results from shoehorning multilevel modular structures into two-level descriptions. As we show, the hierarchical map equation effectively eliminates the resolution limit for networks with nested multilevel modular structures.

  9. Coeval observations of a complete sample of flat-spectrum blazars with Effelsberg, IRAM 30m, and Planck

    NASA Astrophysics Data System (ADS)

    Rachen, Jörg Paul; Fuhrmann, Lars

    2015-08-01

    We present time-resolved broad-band spectra of a complete sample of blazars, selected by showing flat radio spectra up to 143 GHz, taken from observations with Planck, the Effelsberg 100m telescope, and the IRAM 30m telescope. Dedicated Effelsberg observations have been focused on times within two months around Planck single survey scans of each source, with a cadence of 2-4 weeks during the 4th and 5th Planck survey. The data are complemented with flux measurements from the F-GAMMA program (Fuhrmann et. al, 2007, AIPC 921, 249; Fuhrmann et al., 2014, MNRAS 441, 1899), and from other Effelsberg and IRAM monitoring programs, as far as available. Planck data are extracted employing methods used in the blind search for variable sky signals, which allow to estimate snap-shot source fluxes down to pointing period (i.e. hour scale) time resolution (Rachen et al., this conference). The program thus covers 15 frequencies between 2.4 to 857 GHz and is sensitive to variability time scales from hours over weeks up to one year, which is unprecedented in the history of blazar monitoring.

  10. Estimation of Resolution of Shallow Layers by Frequency Domain Airborne Electromagnetic Measurements

    NASA Astrophysics Data System (ADS)

    Smith, B. D.; Minsley, B. J.; Kass, M. A.; Abraham, J. D.; Sams, J. I.; Veloski, G. A.; Esfahani, A.; Hodges, G.

    2012-12-01

    Helicopter frequency domain electromagnetic (HFDEM) that were conducted in two very different geoelectrical settings, permafrost and conductive alluvium, have been used to examine and quantify some aspects of the resolution of shallow layers (less than 5 meters). The surveys have used the Resolve system with six frequencies ranging from 400 Hz to 140 kHz. Though most discussion of the resolution of earth resistivity for airborne EM systems has concentrated on estimating the maximum depth of mapping or the resolution of deep layers, there are important applications for mapping shallow layers and it is useful to understand the capabilities and limitations of the HFDEM system in different environments. In permafrost terrains, mapping of the shallow active layer is important in understanding its distribution relative to surface processes such as thermal history, fires and carbon storage as well as in monitoring applications. Here the shallow active layer is a conductor relative to the very resistive permafrost. Mapping shallow layers in alluvial environments has been the focus of a study of subsurface drip irrigation in the Powder River of Wyoming. Here the focus of the HFDEM study has been in mapping the distribution of conductive clays and naturally occurring saline waters. Mapping of shallow layers in alluvial environments is important in agricultural applications to map recharge, soil salinity, and thickness of alluvium. Parameters for layered models (layer resistivity and thickness) have been estimated by inversion methods and the resolution of parameters has been evaluated using stochastic methods and an evaluation of linear estimates of resolution and uncertainty. Statistical estimates of resolution of parameters are compared with estimates from ground surveys.

  11. Maximum Likelihood Shift Estimation Using High Resolution Polarimetric SAR Clutter Model

    NASA Astrophysics Data System (ADS)

    Harant, Olivier; Bombrun, Lionel; Vasile, Gabriel; Ferro-Famil, Laurent; Gay, Michel

    2011-03-01

    This paper deals with a Maximum Likelihood (ML) shift estimation method in the context of High Resolution (HR) Polarimetric SAR (PolSAR) clutter. Texture modeling is exposed and the generalized ML texture tracking method is extended to the merging of various sensors. Some results on displacement estimation on the Argentiere glacier in the Mont Blanc massif using dual-pol TerraSAR-X (TSX) and quad-pol RADARSAT-2 (RS2) sensors are finally discussed.

  12. Improving high-resolution quantitative precipitation estimation via fusion of multiple radar-based precipitation products

    NASA Astrophysics Data System (ADS)

    Rafieeinasab, Arezoo; Norouzi, Amir; Seo, Dong-Jun; Nelson, Brian

    2015-12-01

    For monitoring and prediction of water-related hazards in urban areas such as flash flooding, high-resolution hydrologic and hydraulic modeling is necessary. Because of large sensitivity and scale dependence of rainfall-runoff models to errors in quantitative precipitation estimates (QPE), it is very important that the accuracy of QPE be improved in high-resolution hydrologic modeling to the greatest extent possible. With the availability of multiple radar-based precipitation products in many areas, one may now consider fusing them to produce more accurate high-resolution QPE for a wide spectrum of applications. In this work, we formulate and comparatively evaluate four relatively simple procedures for such fusion based on Fisher estimation and its conditional bias-penalized variant: Direct Estimation (DE), Bias Correction (BC), Reduced-Dimension Bias Correction (RBC) and Simple Estimation (SE). They are applied to fuse the Multisensor Precipitation Estimator (MPE) and radar-only Next Generation QPE (Q2) products at the 15-min 1-km resolution (Experiment 1), and the MPE and Collaborative Adaptive Sensing of the Atmosphere (CASA) QPE products at the 15-min 500-m resolution (Experiment 2). The resulting fused estimates are evaluated using the 15-min rain gauge observations from the City of Grand Prairie in the Dallas-Fort Worth Metroplex (DFW) in north Texas. The main criterion used for evaluation is that the fused QPE improves over the ingredient QPEs at their native spatial resolutions, and that, at the higher resolution, the fused QPE improves not only over the ingredient higher-resolution QPE but also over the ingredient lower-resolution QPE trivially disaggregated using the ingredient high-resolution QPE. All four procedures assume that the ingredient QPEs are unbiased, which is not likely to hold true in reality even if real-time bias correction is in operation. To test robustness under more realistic conditions, the fusion procedures were evaluated with and

  13. A Global Scale 30m Water Surface Detection Optimized and Validated for Landsat 8

    NASA Astrophysics Data System (ADS)

    Pekel, J. F.; Cottam, A.; Clerici, M.; Belward, A.; Dubois, G.; Bartholome, E.; Gorelick, N.

    2014-12-01

    Life on Earth as we know it is impossible without water. Its importance to biological diversity, human well-being and the very functioning of the Earth-system cannot be overstressed, but we have remarkably little detailed knowledge concerning the spatial and temporal distribution of this vital resource. Earth observing satellites operating with high temporal revisits yet moderate spatial resolution have provided global datasets documenting spatial and temporal changes to water bodies on the Earth's surface. Landsat 8 has a data acquisition strategy such that global coverage of all land surfaces now occurs more frequently than from any preceding Landsat mission and provides 30 m resolution data. Whilst not the last word in temporal sampling this presents a basis for mapping and monitoring changes to global surface water resources at unprecedented levels of spatial detail. In this paper we provide a first 30 m resolution global synthesis of surface water occurrence, we document permanent water surfaces, seasonal water surfaces and always-dry surfaces. These products have been derived by optimizing a methodology previously developed for use with moderate resolution MODIS imagery for use with Landsat 8. The approach is based on a transformation of RGB color space into HSV combined with a sequence of cloud, topographic and temperature masks. Analysis at the global scale used the Google Earth Engine platform applied to all Landsat 8 acquisitions between June 2013 and June 2014. Systematic validation is done and demonstrated our ability to map surface water. Our method can be applied to other Landsat missions offering the potential to document changes in surface water over three decades; our study shows examples illustrating the capacity to map new water surfaces and ephemeral water surfaces in addition to the three previous classes. Thanks to an optimized data acquisition strategy, a full-free and open data policy and the processing capacity of the GEE global land

  14. Global Food Security-support data at 30 m (GFSAD30)

    NASA Astrophysics Data System (ADS)

    Thenkabail, P. S.

    2013-12-01

    Monitoring global croplands (GCs) is imperative for ensuring sustainable water and food security to the people of the world in the Twenty-first Century. However, the currently available cropland products suffer from major limitations such as: (1) Absence of precise spatial location of the cropped areas; (b) Coarse resolution nature of the map products with significant uncertainties in areas, locations, and detail; (b) Uncertainties in differentiating irrigated areas from rainfed areas; (c) Absence of crop types and cropping intensities; and (e) Absence of a dedicated webdata portal for the dissemination of cropland products. Therefore, our project aims to close these gaps through a Global Food Security-support data at 30 m (GFSAD30) with 4 distinct products: 1. Cropland extentarea, 2. Crop types with focus on 8 crops that occupy 70% of the global cropland areas, 3. Irrigated versus rainfed, and 4. Cropping intensities: single, double, triple, and continuous cropping. The above 4 products will be generated for GFSAD for nominal year 2010 (GFSAD2010) based on Landsat 30m Global Land Survey 2010 (GLS2010) fused with Moderate Resolution Imaging Spectroradiometer (MODIS) 250m NDVI monthly maximum value composites (MVC) of 2009-2011 data, and suite of secondary data (e.g., long-term precipitation, temperature, GDEM elevation). GFSAD30 will be produced using three mature cropland mapping algorithms (CMAs): 1. Spectral matching techniques; 2. A cropland classification algorithm (ACCA) that is rule-based; and 3. Hierarchical segmentation (HSeg) algorithm. Funded by NASA MEaSUREs, GFSAD30 will make significant contributions to Earth System Data Records (ESDRs), Group on Earth Observations (GEO) Agriculture and Water Societal Beneficial Areas (GEO Ag. SBAs), GEO Global Agricultural Monitoring Initiative (GEO GLAM), and the recent 'Big Data' initiative by the White House. The project has the support of USGS Working Group on Global Croplands (https://powellcenter.usgs.gov/globalcroplandwater/).

  15. Incorporating PROPACK into PEST to Estimate the Model Resolution Matrix for Large Groundwater Flow Models

    NASA Astrophysics Data System (ADS)

    Muffels, C.; Zhang, H.; Doherty, J.; Tonkin, M.; Hunt, R.; Anderson, M.

    2006-12-01

    Regularized inversion of groundwater flow models can be used to delineate geological heterogeneities using subspace methods like the singular value decomposition (SVD). To characterize heterogeneity, thousands of system parameters and, with appropriate regularization, thousands of observations may be necessary. The SVD method is not practical because it requires significant memory space and is time consuming. In previous work, we demonstrated the LSQR can be used to estimate the many unknown parameters in large groundwater flow inverse problems. However, in doing so, a resolution analysis is needed to characterize the reliability of the resulting model parameters. We adopted an approach developed for large seismic tomography problems and incorporate the PROPACK package into PEST, a model independent parameter estimation program. PROPACK estimates singular values and vectors for large sparse matrices efficiently and accurately based on the Lanczos bidiagonalization, the core of LSQR, with partial reorthogonalization. Unlike other LSQR-based resolution approaches, this PROPACK-based approach calculates the full resolution matrix. We estimate the model resolution matrix for a synthetic approximation based on a regional MODFLOW model of the Trout Lake Basin, Wisconsin, and compare it with results from the more commonly used SVD approach.

  16. Use of UAS remote sensing data to estimate crop ET at high spatial resolution

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Estimation of the spatial distribution of evapotranspiration (ET) based on remotely sensed imagery has become useful for managing water in irrigated agricultural at various spatial scales. However, data acquired by conventional satellites (Landsat, ASTER, etc.) lack the spatial resolution to capture...

  17. High-resolution methane emission estimates using the InTEM inversion system

    NASA Astrophysics Data System (ADS)

    Connors, S.; Manning, A.; Robinson, A. D.; Riddick, S. N.; Forster, G.; Oram, D.; O'Doherty, S.; Harris, N. R. P.

    2014-12-01

    There is a growing need for comparisons between emission estimates produced using bottom-up and top-down techniques at high spatial resolution. In response to this, an inversion approach, InTEM, was adapted to estimate methane emissions for a region in the South East of the UK (~100 x 150 km). We present results covering a 2-year period (July 2012 - July 2014) in which atmospheric methane concentrations were recorded at 1 - 2 minute time-steps at four locations within the region of interest. Precise measurements were obtained using gas chromatography with flame ionisation detection (GC-FID) for all sites except one, which used a PICARRO Cavity Ring-Down Spectrometer (CRDS). These observations, along with the UK Met Office's Lagrangian particle dispersion model (NAME) were used within InTEM to produce the methane emission fields. Emission estimates were produced at varying spatial resolutions, for annual and seasonal time frames . We present results indicating the optimum number of observation sites required for this region, and how this can affect our uncertainty estimates. These results are compared with the UK National Atmospheric Emissions Inventory (NAEI) which is compiled using bottom-up methods and available at 1x1 km resolution. To our knowledge, no inversion technique has been implemented on such a fine spatial resolution. This is a pilot project which, given proof of concept, could be scaled up as an alternative method for producing national scale emission inventories.

  18. High resolution time of arrival estimation for a cooperative sensor system

    NASA Astrophysics Data System (ADS)

    Morhart, C.; Biebl, E. M.

    2010-09-01

    Distance resolution of cooperative sensors is limited by the signal bandwidth. For the transmission mainly lower frequency bands are used which are more narrowband than classical radar frequencies. To compensate this resolution problem the combination of a pseudo-noise coded pulse compression system with superresolution time of arrival estimation is proposed. Coded pulsecompression allows secure and fast distance measurement in multi-user scenarios which can easily be adapted for data transmission purposes (Morhart and Biebl, 2009). Due to the lack of available signal bandwidth the measurement accuracy degrades especially in multipath scenarios. Superresolution time of arrival algorithms can improve this behaviour by estimating the channel impulse response out of a band-limited channel view. For the given test system the implementation of a MUSIC algorithm permitted a two times better distance resolution as the standard pulse compression.

  19. Improved method for estimating tree crown diameter using high-resolution airborne data

    NASA Astrophysics Data System (ADS)

    Brovkina, Olga; Latypov, Iscander Sh.; Cienciala, Emil; Fabianek, Tomas

    2016-04-01

    Automatic mapping of tree crown size (radius, diameter, or width) from remote sensing can provide a major benefit for practical and scientific purposes, but requires the development of accurate methods. This study presents an improved method for average tree crown diameter estimation at a forest plot level from high-resolution airborne data. The improved method consists of the combination of a window binarization procedure and a granulometric algorithm, and avoids the complicated crown delineation procedure that is currently used to estimate crown size. The systematic error in average crown diameter estimates is corrected with the improved method. The improved method is tested with coniferous, beech, and mixed-species forest plots based on airborne images of various spatial resolutions. The absolute (quantitative) accuracy of the improved crown diameter estimates is comparable or higher for both monospecies plots and mixed-species plots than the current methods. The ability of the improved method to produce good estimates for average crown diameters for monoculture and mixed species, to use remote sensing data of various spatial resolution and to operate in automatic mode promisingly suggests its applicability to a wide range of forest systems.

  20. The Impact of Estimating High-Resolution Tropospheric Gradients on Multi-GNSS Precise Positioning.

    PubMed

    Zhou, Feng; Li, Xingxing; Li, Weiwei; Chen, Wen; Dong, Danan; Wickert, Jens; Schuh, Harald

    2017-04-03

    Benefits from the modernized US Global Positioning System (GPS), the revitalized Russian GLObal NAvigation Satellite System (GLONASS), and the newly-developed Chinese BeiDou Navigation Satellite System (BDS) and European Galileo, multi-constellation Global Navigation Satellite System (GNSS) has emerged as a powerful tool not only in positioning, navigation, and timing (PNT), but also in remote sensing of the atmosphere and ionosphere. Both precise positioning and the derivation of atmospheric parameters can benefit from multi-GNSS observations. In this contribution, extensive evaluations are conducted with multi-GNSS datasets collected from 134 globally-distributed ground stations of the International GNSS Service (IGS) Multi-GNSS Experiment (MGEX) network in July 2016. The datasets are processed in six different constellation combinations, i.e., GPS-, GLONASS-, BDS-only, GPS + GLONASS, GPS + BDS, and GPS + GLONASS + BDS + Galileo precise point positioning (PPP). Tropospheric gradients are estimated with eight different temporal resolutions, from 1 h to 24 h, to investigate the impact of estimating high-resolution gradients on position estimates. The standard deviation (STD) is used as an indicator of positioning repeatability. The results show that estimating tropospheric gradients with high temporal resolution can achieve better positioning performance than the traditional strategy in which tropospheric gradients are estimated on a daily basis. Moreover, the impact of estimating tropospheric gradients with different temporal resolutions at various elevation cutoff angles (from 3° to 20°) is investigated. It can be observed that with increasing elevation cutoff angles, the improvement in positioning repeatability is decreased.

  1. Alternative techniques for high-resolution spectral estimation of spectrally encoded endoscopy

    NASA Astrophysics Data System (ADS)

    Mousavi, Mahta; Duan, Lian; Javidi, Tara; Ellerbee, Audrey K.

    2015-09-01

    Spectrally encoded endoscopy (SEE) is a minimally invasive optical imaging modality capable of fast confocal imaging of internal tissue structures. Modern SEE systems use coherent sources to image deep within the tissue and data are processed similar to optical coherence tomography (OCT); however, standard processing of SEE data via the Fast Fourier Transform (FFT) leads to degradation of the axial resolution as the bandwidth of the source shrinks, resulting in a well-known trade-off between speed and axial resolution. Recognizing the limitation of FFT as a general spectral estimation algorithm to only take into account samples collected by the detector, in this work we investigate alternative high-resolution spectral estimation algorithms that exploit information such as sparsity and the general region position of the bulk sample to improve the axial resolution of processed SEE data. We validate the performance of these algorithms using bothMATLAB simulations and analysis of experimental results generated from a home-built OCT system to simulate an SEE system with variable scan rates. Our results open a new door towards using non-FFT algorithms to generate higher quality (i.e., higher resolution) SEE images at correspondingly fast scan rates, resulting in systems that are more accurate and more comfortable for patients due to the reduced image time.

  2. Estimation of size of cord blood inventory based on high-resolution typing of HLAs.

    PubMed

    Song, E Y; Huh, J Y; Kim, S Y; Kim, T G; Oh, S; Yoon, J H; Roh, E Y; Park, M H; Kang, M S; Shin, S

    2014-07-01

    Methods for estimating the cord blood (CB) inventory size required vary according to the ethnic diversity of the HLA, degree of HLA matching and HLA-typing resolution. We estimated the CB inventory size required using 7190 stored CB units (CBU) and 2450 patients who were awaiting or underwent allogeneic hematopoietic stem cell transplantation. With high-resolution typing of HLA-A, B and DRB1, 94.6% of Korean patients could find CBUs in 100 000 CBUs with a 5/6 match, and 95.7% could find CBUs in 5000 CBUs with a 4/6 match. With low-resolution typing of HLA-A and B and high-resolution typing of leukocyte antigen-DRB1, 95% of patients could find CBUs in 50 000 CBUs with a 5/6 match, and 96.7% could find CBUs in 3000 CBUs  with a 4/6 match. With additional high-resolution typing for HLA-A and B, which could improve transplantation outcome, the size of the CB inventory would need to increase twofold for Koreans.

  3. Computational estimation of resolution in reconstruction techniques utilizing sparsity, total variation, and nonnegativity

    NASA Astrophysics Data System (ADS)

    Dillon, Keith; Fainman, Yeshaiahu; Wang, Yu-Ping

    2016-09-01

    Techniques which exploit properties such as sparsity and total variation have provided the ability to reconstruct images that surpass the conventional limits of imaging. This leads to difficulties in assessing the result, as conventional metrics for resolution are no longer valid. We develop a numerical approach to evaluating the second-order statistics of the estimate by relating a confidence interval on the solution to a confidence interval on a pixel value, and from this we formulate an approach to estimating the spatial resolution. With this estimate, we can calculate the resolution at each point subject to chosen bounds on the desired precision and confidence. We demonstrate the method for limited-angle tomographic reconstructions utilizing nonnegativity, sparse regularization, total-variation minimization, and their combinations. This provides a means to visualize and understand the effect on the image inherent in these penalties and constraints. Examples are provided using simulated data for different methods, and the results are shown to agree with resolution calculated empirically via the local edge response.

  4. Estimation of High Resolution Estimates of Soil Moisture Change and Their Assimilation Into a Land Surface Model

    NASA Astrophysics Data System (ADS)

    Narayan, U.; Lakshmi, V.

    2005-12-01

    A methodology that combines active and passive microwave and optical remote sensing data to arrive at disaggregated estimates of soil moisture change is developed. The technique relies on sensitivity of passive microwave radiation in the L- band to soil moisture, sensitivity of active microwave data in the L- band to surface roughness and soil moisture, and the sensitivity of optical data to vegetation water content, in order to disaggregate soil moisture change estimated from passive microwave data to the higher spatial resolution of radar operation. The methodology involves correction of radar backscattering coefficients for surface roughness variability and vegetation water attenuation effects. From the corrected radar backscatter change estimates, soil moisture change estimates are derived using a semi empirical model for radar backscatter. Soil moisture change is closely related to soil hydraulic properties and assimilation of surface layer soil moisture change estimates into a hydrologic model will potentially improve its performance. Assimilation technique and initial results from an assimilation exercise are presented. The data used in the study were collected during the SMEX02 campaign conducted in the Walnut Creek region of Iowa in 2002. Techniques presented in this study have the potential to be applied to HYDROS data in the future.

  5. High-resolution optical spectrum characterization using optical channel estimation and spectrum stitching technique.

    PubMed

    Jin, Chao; Bao, Yuan; Li, Zhaohui; Gui, Tao; Shang, Haiyan; Feng, Xinhuan; Li, Jianping; Yi, Xingwen; Yu, Changyuan; Li, Guifang; Lu, Chao

    2013-07-01

    A technique is proposed to measure the high-resolution and wide-band characterization of amplitude, phase responses, and polarization property of optical components. This technique combines the optical spectrum stitching and optical channel estimation methods. Two kinds of fiber Bragg grating based Fabry-Perot cavities with ultrafine structures have been characterized based on this technique. By using 1024 point fast Fourier transform and a narrow linewidth, wavelength-tunable laser source, a frequency resolution of ~10 MHz is realized with an optical measurement range beyond 250 GHz.

  6. The use of high spectral resolution bands for estimating absorbed photosynthetically active radiation (A par)

    NASA Technical Reports Server (NTRS)

    Kim, Moon S.; Daughtry, C. S. T.; Chappelle, E. W.; Mcmurtrey, J. E.; Walthall, C. L.

    1994-01-01

    Most remote sensing estimations of vegetation variables such as Leaf Area Index (LAI), Absorbed Photosynthetically Active Radiation (APAR), and phytomass are made using broad band sensors with a bandwidth of approximately 100 nm. However, high resolution spectrometers are available and have not been fully exploited for the purpose of improving estimates of vegetation variables. A study directed to investigate the use of high spectral resolution spectroscopy for remote sensing estimates of APAR in vegetation canopies in the presence of nonphotosynthetic background materials such as soil and leaf litter is presented. A high spectral resolution method defined as the Chlorophyll Absorption Ratio Index (CARI) was developed for minimizing the effects of nonphotosynthetic materials in the remote estimates of APAR. CARI utilizes three bands at 550, 670, and 700 nm with bandwidth of 10 nm. Simulated canopy reflectance of a range of LAI were generated with the SAIL model using measurements of 42 different soil types as canopy background. CARI obtained from the simulated canopy reflectance was compared with the broad band vegetation indices (Normalized Difference Vegetation Index (NDVI), Soil Adjusted Vegetation Index (SAVI), and Simple Ratio (SR)). CARI reduced the effect of nonphotosynthetic background materials in the assessment of vegetation canopy APAR more effectively than broad band vegetation indices.

  7. Forest classification and impact of BIOMASS resolution on forest area and aboveground biomass estimation

    NASA Astrophysics Data System (ADS)

    Schlund, Michael; Scipal, Klaus; Davidson, Malcolm W. J.

    2017-04-01

    The European Space Agency (ESA) is currently implementing the BIOMASS mission as 7th Earth Explorer satellite. BIOMASS will provide for the first time global forest aboveground biomass estimates based on P-band synthetic aperture radar (SAR) imagery. This paper addresses an often overlooked element of the data processing chain required to ensure reliable and accurate forest biomass estimates: accurate identification of forest areas ahead of the inversion of radar data into forest biomass estimates. The use of the P-band data from BIOMASS itself for the classification into forest and non-forest land cover types is assessed in this paper. For airborne data in tropical, hemi-boreal and boreal forests we demonstrate that classification accuracies from 90 up to 97% can be achieved using radar backscatter and phase information. However, spaceborne data will have a lower resolution and higher noise level compared to airborne data and a higher probability of mixed pixels containing multiple land cover types. Therefore, airborne data was reduced to 50 m, 100 m and 200 m resolution. The analysis revealed that about 50-60% of the area within the resolution level must be covered by forest to classify a pixel with higher probability as forest compared to non-forest. This results in forest omission and commission leading to similar forest area estimation over all resolutions. However, the forest omission resulted in a biased underestimated biomass, which was not equaled by the forest commission. The results underline the necessity of a highly accurate pre-classification of SAR data for an accurate unbiased aboveground biomass estimation.

  8. A 30 mK, 13.5 T scanning tunneling microscope with two independent tips

    SciTech Connect

    Roychowdhury, Anita; Gubrud, M. A.; Dana, R.; Dreyer, M.; Anderson, J. R.; Lobb, C. J.; Wellstood, F. C.

    2014-04-15

    We describe the design, construction, and performance of an ultra-low temperature, high-field scanning tunneling microscope (STM) with two independent tips. The STM is mounted on a dilution refrigerator and operates at a base temperature of 30 mK with magnetic fields of up to 13.5 T. We focus on the design of the two-tip STM head, as well as the sample transfer mechanism, which allows in situ transfer from an ultra high vacuum preparation chamber while the STM is at 1.5 K. Other design details such as the vibration isolation and rf-filtered wiring are also described. Their effectiveness is demonstrated via spectral current noise characteristics and the root mean square roughness of atomic resolution images. The high-field capability is shown by the magnetic field dependence of the superconducting gap of Cu{sub x}Bi{sub 2}Se{sub 3}. Finally, we present images and spectroscopy taken with superconducting Nb tips with the refrigerator at 35 mK that indicate that the effective temperature of our tips/sample is approximately 184 mK, corresponding to an energy resolution of 16 μeV.

  9. A 30 mK, 13.5 T scanning tunneling microscope with two independent tips

    NASA Astrophysics Data System (ADS)

    Roychowdhury, Anita; Gubrud, M. A.; Dana, R.; Anderson, J. R.; Lobb, C. J.; Wellstood, F. C.; Dreyer, M.

    2014-04-01

    We describe the design, construction, and performance of an ultra-low temperature, high-field scanning tunneling microscope (STM) with two independent tips. The STM is mounted on a dilution refrigerator and operates at a base temperature of 30 mK with magnetic fields of up to 13.5 T. We focus on the design of the two-tip STM head, as well as the sample transfer mechanism, which allows in situ transfer from an ultra high vacuum preparation chamber while the STM is at 1.5 K. Other design details such as the vibration isolation and rf-filtered wiring are also described. Their effectiveness is demonstrated via spectral current noise characteristics and the root mean square roughness of atomic resolution images. The high-field capability is shown by the magnetic field dependence of the superconducting gap of CuxBi2Se3. Finally, we present images and spectroscopy taken with superconducting Nb tips with the refrigerator at 35 mK that indicate that the effective temperature of our tips/sample is approximately 184 mK, corresponding to an energy resolution of 16 μeV.

  10. A 30 mK, 13.5 T scanning tunneling microscope with two independent tips.

    PubMed

    Roychowdhury, Anita; Gubrud, M A; Dana, R; Anderson, J R; Lobb, C J; Wellstood, F C; Dreyer, M

    2014-04-01

    We describe the design, construction, and performance of an ultra-low temperature, high-field scanning tunneling microscope (STM) with two independent tips. The STM is mounted on a dilution refrigerator and operates at a base temperature of 30 mK with magnetic fields of up to 13.5 T. We focus on the design of the two-tip STM head, as well as the sample transfer mechanism, which allows in situ transfer from an ultra high vacuum preparation chamber while the STM is at 1.5 K. Other design details such as the vibration isolation and rf-filtered wiring are also described. Their effectiveness is demonstrated via spectral current noise characteristics and the root mean square roughness of atomic resolution images. The high-field capability is shown by the magnetic field dependence of the superconducting gap of CuxBi2Se3. Finally, we present images and spectroscopy taken with superconducting Nb tips with the refrigerator at 35 mK that indicate that the effective temperature of our tips/sample is approximately 184 mK, corresponding to an energy resolution of 16 μeV.

  11. High Resolution DOA Estimation Using Unwrapped Phase Information of MUSIC-Based Noise Subspace

    NASA Astrophysics Data System (ADS)

    Ichige, Koichi; Saito, Kazuhiko; Arai, Hiroyuki

    This paper presents a high resolution Direction-Of-Arrival (DOA) estimation method using unwrapped phase information of MUSIC-based noise subspace. Superresolution DOA estimation methods such as MUSIC, Root-MUSIC and ESPRIT methods are paid great attention because of their brilliant properties in estimating DOAs of incident signals. Those methods achieve high accuracy in estimating DOAs in a good propagation environment, but would fail to estimate DOAs in severe environments like low Signal-to-Noise Ratio (SNR), small number of snapshots, or when incident waves are coming from close angles. In MUSIC method, its spectrum is calculated based on the absolute value of the inner product between array response and noise eigenvectors, means that MUSIC employs only the amplitude characteristics and does not use any phase characteristics. Recalling that phase characteristics plays an important role in signal and image processing, we expect that DOA estimation accuracy could be further improved using phase information in addition to MUSIC spectrum. This paper develops a procedure to obtain an accurate spectrum for DOA estimation using unwrapped and differentiated phase information of MUSIC-based noise subspace. Performance of the proposed method is evaluated through computer simulation in comparison with some conventional estimation methods.

  12. Impulse Response Estimation for Spatial Resolution Enhancement in Ultrasonic NDE Imaging

    SciTech Connect

    Clark, G A

    2004-06-25

    This report describes a signal processing algorithm and MATLAB software for improving spatial resolution in ultrasonic nondestructive evaluation (NDE) imaging of materials. Given a measured reflection signal and an associated reference signal, the algorithm produces an optimal least-squares estimate of the impulse response of the material under test. This estimated impulse response, when used in place of the raw reflection signal, enhances the spatial resolution of the ultrasonic measurements by removing distortion caused by the limited-bandwidth transducers and the materials under test. The theory behind the processing algorithms is briefly presented, while the reader is referred to the bibliography for details. The main focus of the report is to describe how to use the MATLAB software. Two processing examples using actual ultrasonic measurements are provided for tutorial purposes.

  13. Estimation of time resolution for DOI-PET detector using diameter 0.2 mm WLS fibers

    SciTech Connect

    Kobayashi, A.; Ito, H.; Han, S.; Kaneko, N.; Kawai, H.; Kodama, S.; Han, S.; Kamada, K.; Shoji, Y.; Yoshikawa, A.

    2015-07-01

    We are developing the whole-body PET detector with high position resolution (1 mm) and low cost (1 M dollars). Scintillator plates, Wave Length Sifting Fibers and SiPMs are used. In this work, time resolution of our PET detector is estimated. Our detector may also have good time resolution such as a few ps. (authors)

  14. Cumulus cloud base height estimation from high spatial resolution Landsat data - A Hough transform approach

    NASA Technical Reports Server (NTRS)

    Berendes, Todd; Sengupta, Sailes K.; Welch, Ron M.; Wielicki, Bruce A.; Navar, Murgesh

    1992-01-01

    A semiautomated methodology is developed for estimating cumulus cloud base heights on the basis of high spatial resolution Landsat MSS data, using various image-processing techniques to match cloud edges with their corresponding shadow edges. The cloud base height is then estimated by computing the separation distance between the corresponding generalized Hough transform reference points. The differences between the cloud base heights computed by these means and a manual verification technique are of the order of 100 m or less; accuracies of 50-70 m may soon be possible via EOS instruments.

  15. Disaster debris estimation using high-resolution polarimetric stereo-SAR

    NASA Astrophysics Data System (ADS)

    Koyama, Christian N.; Gokon, Hideomi; Jimbo, Masaru; Koshimura, Shunichi; Sato, Motoyuki

    2016-10-01

    This paper addresses the problem of debris estimation which is one of the most important initial challenges in the wake of a disaster like the Great East Japan Earthquake and Tsunami. Reasonable estimates of the debris have to be made available to decision makers as quickly as possible. Current approaches to obtain this information are far from being optimal as they usually rely on manual interpretation of optical imagery. We have developed a novel approach for the estimation of tsunami debris pile heights and volumes for improved emergency response. The method is based on a stereo-synthetic aperture radar (stereo-SAR) approach for very high-resolution polarimetric SAR. An advanced gradient-based optical-flow estimation technique is applied for optimal image coregistration of the low-coherence non-interferometric data resulting from the illumination from opposite directions and in different polarizations. By applying model based decomposition of the coherency matrix, only the odd bounce scattering contributions are used to optimize echo time computation. The method exclusively considers the relative height differences from the top of the piles to their base to achieve a very fine resolution in height estimation. To define the base, a reference point on non-debris-covered ground surface is located adjacent to the debris pile targets by exploiting the polarimetric scattering information. The proposed technique is validated using in situ data of real tsunami debris taken on a temporary debris management site in the tsunami affected area near Sendai city, Japan. The estimated height error is smaller than 0.6 m RMSE. The good quality of derived pile heights allows for a voxel-based estimation of debris volumes with a RMSE of 1099 m3. Advantages of the proposed method are fast computation time, and robust height and volume estimation of debris piles without the need for pre-event data or auxiliary information like DEM, topographic maps or GCPs.

  16. Fragmented Land Cover Types and Estimation of Area with Course Spatial Resolution Imagery

    NASA Technical Reports Server (NTRS)

    Hlavka, Chris; Dungan, Jennifer; Gore, William (Technical Monitor)

    1998-01-01

    Imagery of coarse resolution, such weather satellite imagery with 1 sq km pixels, is increasingly used to monitor dynamic and fragmented types of land surface types, such as scars from recent fires and ponds in wetlands. Accurate estimates of these land cover types at regional to global scales are required to assess the roles of fires and wetlands in global warming, yet difficult to compute when much of the area is accounted for by fragments about the same size as the pixels. In previous research, we found that size distribution of the fragments in several example scenes fit simple two-parameter models and related effects of coarse resolution to errors in area estimates based on pixel counts. We report on progress to develop accurate area estimates based on modelling the size distribution of the fragments, including analysis of size distributions on an expanded set of maps developed from digital imagery and a test of a procedure to correct for effects of coarse spatial resolution.

  17. Using high time resolution aerosol and number size distribution measurements to estimate atmospheric extinction.

    PubMed

    Malm, William C; McMeeking, Gavin R; Kreidenweis, Sonia M; Levin, Ezra; Carrico, Christian M; Day, Derek E; Collett, Jeffrey L; Lee, Taehyoung; Sullivan, Amy P; Raja, Suresh

    2009-09-01

    Rocky Mountain National Park is experiencing reduced visibility and changes in ecosystem function due to increasing levels of oxidized and reduced nitrogen. The Rocky Mountain Atmospheric Nitrogen and Sulfur (RoMANS) study was initiated to better understand the origins of sulfur and nitrogen species as well as the complex chemistry occurring during transport from source to receptor. As part of the study, a monitoring program was initiated for two 1-month time periods--one during the spring and the other during late summer/fall. The monitoring program included intensive high time resolution concentration measurements of aerosol number size distribution, inorganic anions, and cations, and 24-hr time resolution of PM2.5 and PM10 mass, sulfate, nitrate, carbon, and soil-related elements concentrations. These data are combined to estimate high time resolution concentrations of PM2.5 and PM10 aerosol mass and fine mass species estimates of ammoniated sulfate, nitrate, and organic and elemental carbon. Hour-by-hour extinction budgets are calculated by using these species concentration estimates and measurements of size distribution and assuming internal and external particle mixtures. Summer extinction was on average about 3 times higher than spring extinction. During spring months, sulfates, nitrates, carbon mass, and PM10 - PM2.5 mass contributed approximately equal amounts of extinction, whereas during the summer months, carbonaceous material extinction was 2-3 times higher than other species.

  18. A MAP approach for joint motion estimation, segmentation, and super resolution.

    PubMed

    Shen, Huanfeng; Zhang, Liangpei; Huang, Bo; Li, Pingxiang

    2007-02-01

    Super resolution image reconstruction allows the recovery of a high-resolution (HR) image from several low-resolution images that are noisy, blurred, and down sampled. In this paper, we present a joint formulation for a complex super-resolution problem in which the scenes contain multiple independently moving objects. This formulation is built upon the maximum a posteriori (MAP) framework, which judiciously combines motion estimation, segmentation, and super resolution together. A cyclic coordinate descent optimization procedure is used to solve the MAP formulation, in which the motion fields, segmentation fields, and HR images are found in an alternate manner given the two others, respectively. Specifically, the gradient-based methods are employed to solve the HR image and motion fields, and an iterated conditional mode optimization method to obtain the segmentation fields. The proposed algorithm has been tested using a synthetic image sequence, the "Mobile and Calendar" sequence, and the original "Motorcycle and Car" sequence. The experiment results and error analyses verify the efficacy of this algorithm.

  19. RESEARCH PAPER: Automated estimation of stellar fundamental parameters from low resolution spectra: the PLS method

    NASA Astrophysics Data System (ADS)

    Zhang, Jian-Nan; Luo, A.-Li; Zhao, Yong-Heng

    2009-06-01

    PLS (Partial Least Squares regression) is introduced into an automatic estimation of fundamental stellar spectral parameters. It extracts the most correlative spectral component to the parameters (Teff, log g and [Fe/H]), and sets up a linear regression function from spectra to the corresponding parameters. Considering the properties of stellar spectra and the PLS algorithm, we present a piecewise PLS regression method for estimation of stellar parameters, which is composed of one PLS model for Teff, and seven PLS models for log g and [Fe/H] estimation. Its performance is investigated by large experiments on flux calibrated spectra and continuum normalized spectra at different signal-to-noise ratios (SNRs) and resolutions. The results show that the piecewise PLS method is robust for spectra at the medium resolution of 0.23 nm. For low resolution 0.5 nm and 1 nm spectra, it achieves competitive results at higher SNR. Experiments using ELODIE spectra of 0.23 nm resolution illustrate that our piecewise PLS models trained with MILES spectra are efficient for O ~ G stars: for flux calibrated spectra, the systematic offsets are 3.8%, 0.14 dex, and -0.09 dex for Teff, log g and [Fe/H], with error scatters of 5.2%, 0.44 dex and 0.38 dex, respectively; for continuum normalized spectra, the systematic offsets are 3.8%, 0.12dex, and -0.13dex for Teff, log g and [Fe/H], with error scatters of 5.2%, 0.49 dex and 0.41 dex, respectively. The PLS method is rapid, easy to use and does not rely as strongly on the tightness of a parameter grid of templates to reach high precision as Artificial Neural Networks or minimum distance methods do.

  20. Spectral estimation optical coherence tomography for axial super-resolution (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Liu, Xinyu; Yu, Xiaojun; Wang, Nanshuo; Bo, En; Luo, Yuemei; Chen, Si; Cui, Dongyao; Liu, Linbo

    2016-03-01

    The sample depth reflectivity profile of Fourier domain optical coherence tomography (FD-OCT) is estimated from the inverse Fourier transform of the spectral interference signals (interferograms). As a result, the axial resolution is fundamentally limited by the coherence length of the light source. We demonstrate an axial resolution improvement method by using the autoregressive spectral estimation technique to instead of the inverse Fourier transform to analyze the spectral interferograms, which is named as spectral estimation OCT (SE-OCT). SE-OCT improves the axial resolution by a factor of up to 4.7 compared with the corresponding FD-OCT. Furthermore, SE-OCT provides a complete sidelobe suppression in the point-spread function. Using phantoms such as an air wedge and micro particles, we prove the ability of resolution improvement. To test SE-OCT for real biological tissue, we image the rat cornea and demonstrate that SE-OCT enables clear identification of corneal endothelium anatomical details ex vivo. We also find that the performance of SE-OCT is depended on SNR of the feature object. To evaluate the potential usage and define the application scope of SE-OCT, we further investigate the property of SNR dependence and the artifacts that may be caused. We find SE-OCT may be uniquely suited for viewing high SNR layer structures, such as the epithelium and endothelium in cornea, retina and aorta. Given that SE-OCT can be implemented in the FD-OCT devices easily, the new capabilities provided by SE-OCT are likely to offer immediate improvements to the diagnosis and management of diseases based on OCT imaging.

  1. CMORPH Global High-Resolution Precipitation Estimates: Reprocessing, Bias Correction, and Error Quantification

    NASA Astrophysics Data System (ADS)

    Xie, P.; Joyce, R.; Wu, S.

    2015-12-01

    CMORPH global high-resolution satellite precipitation estimates have been reprocessed and bias-corrected for an 18-year period from January 1998 to the present to cover the entire TRMM/GPM era. As the first step of this project, the CMORPH estimates have been reprocessed with a frozen algorithm and with input PMW retrievals and IR observations of identical versions throughout the data period. Bias correction is then performed for the reprocessed CMORPH over the entire data period from 1998 to the present. Over land, the bias in the raw CMORPH is removed by matching the probability density function (PDF) of the CMORPH with that of the CPC unified daily gauge analysis. Over ocean, the raw CMORPH satellite estimates are calibrated against a long-term precipitation analysis (pentad GPCP) to ensure temporal homogeneity for climate applications. The reprocessed, bias-corrected CMORPH estimates present an 18-year homogeneous record of high-resolution precipitation on an 8kmx8km and 30-min resolution covering the globe from 60oS-60oN. Accuracy of the reprocessed, bias corrected CMORPH is examined through comparison against gauge based analysis over land and against buoy measurements over ocean. Overall, the bias corrected CMORPH exhibited improved performance upon the raw CMORPH, with bias removed almost completely over the tropics and extra-tropical regions during warm seasons. Caused by shortcomings in the input PMW retrievals, CMORPH tends to miss precipitation over cold surfaces. Quantitative accuracy of bias corrected CMORPH is a function of season, location, precipitation intensity, and the availability of satellite retrievals. Bias corrected CMORPH is applied to examine the large-scale precipitation variations over the globe. In particular, diurnal variations of precipitation is investigated and compared with those determined by the three new generation reanalyses (CFSR, MERRA, and ERA-Interim). A comprehensive description and diagnostic discussions will be given at

  2. High-resolution methane emission estimates using surface measurements and the InTEM inversion system.

    NASA Astrophysics Data System (ADS)

    Connors, Sarah; Manning, Alistair; Robinson, Andrew; Riddick, Stuart; Forster, Grant; Oram, Dave; O'Doherty, Simon; Harris, Neil

    2015-04-01

    High quality GHG emission estimates will be required to successfully tackle climate change. There is a growing need for comparisons between emission estimates produced using bottom-up and top-down techniques at high spatial resolution. Here, a top-down inversion approach combining multi-year atmospheric measurements and an inversion model, InTEM, was used to estimate methane emissions for a region in the South East of the UK (~100 x 150 km). We present results covering a 2-year period (July 2012 - July 2014) in which atmospheric methane concentrations were recorded at 1 - 2 minute time-steps at four locations within the region of interest. Precise measurements were obtained using gas chromatography with flame ionisation detection (GC-FID) for all sites except one, which used a PICARRO Cavity Ring-Down Spectrometer (CRDS). These observations, along with the UK Met Office's Lagrangian particle dispersion model, NAME, were used within InTEM to produce the methane emission fields. We present results from both Bayesian and non-prior based inversion analysis at varying spatial resolutions, for annual, seasonal and monthly time frames. These results are compared with the UK National Atmospheric Emissions Inventory (NAEI) which is compiled using bottom-up methods and available at 1x1 km resolution. A thorough assessment of uncertainty is incorporated into this technique which is represented in the results. This project is part of the UK GAUGE campaign which aims to produce robust estimates of the UK GHG budget using new and existing measurement networks (e.g. the UK DECC GHG network) and modelling activities at a range of scales.

  3. High Resolution Deformation Time Series Estimation for Distributed Scatterers Using Terrasar-X Data

    NASA Astrophysics Data System (ADS)

    Goel, K.; Adam, N.

    2012-07-01

    In recent years, several SAR satellites such as TerraSAR-X, COSMO-SkyMed and Radarsat-2 have been launched. These satellites provide high resolution data suitable for sophisticated interferometric applications. With shorter repeat cycles, smaller orbital tubes and higher bandwidth of the satellites; deformation time series analysis of distributed scatterers (DSs) is now supported by a practical data basis. Techniques for exploiting DSs in non-urban (rural) areas include the Small Baseline Subset Algorithm (SBAS). However, it involves spatial phase unwrapping, and phase unwrapping errors are typically encountered in rural areas and are difficult to detect. In addition, the SBAS technique involves a rectangular multilooking of the differential interferograms to reduce phase noise, resulting in a loss of resolution and superposition of different objects on ground. In this paper, we introduce a new approach for deformation monitoring with a focus on DSs, wherein, there is no need to unwrap the differential interferograms and the deformation is mapped at object resolution. It is based on a robust object adaptive parameter estimation using single look differential interferograms, where, the local tilts of deformation velocity and local slopes of residual DEM in range and azimuth directions are estimated. We present here the technical details and a processing example of this newly developed algorithm.

  4. Rainfall erosivity estimation based on rainfall data collected over a range of temporal resolutions

    NASA Astrophysics Data System (ADS)

    Yin, S.; Xie, Y.; Liu, B.; Nearing, M. A.

    2015-10-01

    Rainfall erosivity is the power of rainfall to cause soil erosion by water. The rainfall erosivity index for a rainfall event (energy-intensity values - EI30) is calculated from the total kinetic energy and maximum 30 min intensity of individual events. However, these data are often unavailable in many areas of the world. The purpose of this study was to develop models based on commonly available rainfall data resolutions, such as daily or monthly totals, to calculate rainfall erosivity. Eleven stations with 1 min temporal resolution rainfall data collected from 1961 through 2000 in the eastern half of China were used to develop and calibrate 21 models. Seven independent stations, also with 1 min data, were utilized to validate those models, together with 20 previously published equations. The models in this study performed better or similar to models from previous research to estimate rainfall erosivity for these data. Using symmetric mean absolute percentage errors and Nash-Sutcliffe model efficiency coefficients, we can recommend 17 of the new models that had model efficiencies ≥ 0.59. The best prediction capabilities resulted from using the finest resolution rainfall data as inputs at a given erosivity timescale and by summing results from equations for finer erosivity timescales where possible. Results from this study provide a number of options for developing erosivity maps using coarse resolution rainfall data.

  5. Evaluation of spatial resolution of satellite data on snow cover estimates

    NASA Astrophysics Data System (ADS)

    Porhemmat, J.; Saghafian, B.

    2003-04-01

    Snow cover area is one of the most important components in snowmelt runoff modelling. Snow cover extent and its variation can not be reasonably detected by ground survey. Therefore, remote sensing is an important alternative for snow cover extent estimates and its spatial and temporal variation. Despite having many satellites scanning earth surface, most do not meet the needs of producing time series of daily snow cover needed in hydrology and water resources planning. The satellites such as SPOT and Landsat with high spatial resolution (28.5 and 10-15 meters per pixel) pass over earth every 16 and 26 days, respectively. This means that if a pass was affected by cloudy condition, the time interval of receiving a suitable image could be more than one month. However, the pass made by NOAA is every 12 hours with a nominal resolution of 1100 meters per pixel. Thus the effect of spatial resolution of remotely sensed data on accuracy of snow cover area must be assessed. This research involves selection of a high-resolution and a low-resolution sensor, which are respectively Landsat TM (Thematic Mapper) and NOAA AVHRR (Advanced Very High Resolution Radiometers). Landsat can detect small parcels of snow, which may not be detected by NOAA AVHRR. Zagross high lands, upstream of Karun river basin in southwest of Iran, is a seasonally covered by snow and are selected for the study area. Two simultaneous passes of Landsat and NOAA are chosen for evaluation of snow cover. The dates of these passes are 13 April 1997 and 18 May 1998. The first one corresponds to the early stage of snowmelt period and the second one to the end stage of snowmelt period. The whole study area corresponds to a full scene of Landsat, which cover an area of about 34000 Km2. There were many scattered and separate snow parcels on both dates. Snow area was detected by two methods. First method was interpretation and digitizing snow line on monitor screen and the second one was supervised classification

  6. On-line 3D motion estimation using low resolution MRI

    NASA Astrophysics Data System (ADS)

    Glitzner, M.; de Senneville, B. Denis; Lagendijk, J. J. W.; Raaymakers, B. W.; Crijns, S. P. M.

    2015-08-01

    Image processing such as deformable image registration finds its way into radiotherapy as a means to track non-rigid anatomy. With the advent of magnetic resonance imaging (MRI) guided radiotherapy, intrafraction anatomy snapshots become technically feasible. MRI provides the needed tissue signal for high-fidelity image registration. However, acquisitions, especially in 3D, take a considerable amount of time. Pushing towards real-time adaptive radiotherapy, MRI needs to be accelerated without degrading the quality of information. In this paper, we investigate the impact of image resolution on the quality of motion estimations. Potentially, spatially undersampled images yield comparable motion estimations. At the same time, their acquisition times would reduce greatly due to the sparser sampling. In order to substantiate this hypothesis, exemplary 4D datasets of the abdomen were downsampled gradually. Subsequently, spatiotemporal deformations are extracted consistently using the same motion estimation for each downsampled dataset. Errors between the original and the respectively downsampled version of the dataset are then evaluated. Compared to ground-truth, results show high similarity of deformations estimated from downsampled image data. Using a dataset with {{≤ft(2.5 \\text{mm}\\right)}3} voxel size, deformation fields could be recovered well up to a downsampling factor of 2, i.e. {{≤ft(5 \\text{mm}\\right)}3} . In a therapy guidance scenario MRI, imaging speed could accordingly increase approximately fourfold, with acceptable loss of estimated motion quality.

  7. Fast integer least-squares estimation for GNSS high-dimensional ambiguity resolution using lattice theory

    NASA Astrophysics Data System (ADS)

    Jazaeri, S.; Amiri-Simkooei, A. R.; Sharifi, M. A.

    2012-02-01

    GNSS ambiguity resolution is the key issue in the high-precision relative geodetic positioning and navigation applications. It is a problem of integer programming plus integer quality evaluation. Different integer search estimation methods have been proposed for the integer solution of ambiguity resolution. Slow rate of convergence is the main obstacle to the existing methods where tens of ambiguities are involved. Herein, integer search estimation for the GNSS ambiguity resolution based on the lattice theory is proposed. It is mathematically shown that the closest lattice point problem is the same as the integer least-squares (ILS) estimation problem and that the lattice reduction speeds up searching process. We have implemented three integer search strategies: Agrell, Eriksson, Vardy, Zeger (AEVZ), modification of Schnorr-Euchner enumeration (M-SE) and modification of Viterbo-Boutros enumeration (M-VB). The methods have been numerically implemented in several simulated examples under different scenarios and over 100 independent runs. The decorrelation process (or unimodular transformations) has been first used to transform the original ILS problem to a new one in all simulations. We have then applied different search algorithms to the transformed ILS problem. The numerical simulations have shown that AEVZ, M-SE, and M-VB are about 320, 120 and 50 times faster than LAMBDA, respectively, for a search space of dimension 40. This number could change to about 350, 160 and 60 for dimension 45. The AEVZ is shown to be faster than MLAMBDA by a factor of 5. Similar conclusions could be made using the application of the proposed algorithms to the real GPS data.

  8. IRAM 30 m Large Scale Survey of 12CO(2-1) and 13CO(2-1) Emission in the Orion Molecular Cloud

    NASA Astrophysics Data System (ADS)

    Berné, O.; Marcelino, N.; Cernicharo, J.

    2014-11-01

    Using the IRAM 30 m telescope, we have surveyed a 1 × 0.°8 part of the Orion molecular cloud in the 12CO and 13CO (2-1) lines with a maximal spatial resolution of ~11'' and spectral resolution of ~0.4 km s-1. The cloud appears filamentary, clumpy, and with a complex kinematical structure. We derive an estimated mass of the cloud of 7700 M ⊙ (half of which is found in regions with visual extinctions AV below ~10) and a dynamical age for the nebula of the order of 0.2 Myr. The energy balance suggests that magnetic fields play an important role in supporting the cloud, at large and small scales. According to our analysis, the turbulent kinetic energy in the molecular gas due to outflows is comparable to turbulent kinetic energy resulting from the interaction of the cloud with the H II region. This latter feedback appears negative, i.e., the triggering of star formation by the H II region is inefficient in Orion. The reduced data as well as additional products such as the column density map are made available online (http://userpages.irap.omp.eu/~oberne/Olivier_Berne/Data).

  9. Improved global high resolution precipitation estimation using multi-satellite multi-spectral information

    NASA Astrophysics Data System (ADS)

    Behrangi, Ali

    In respond to the community demands, combining microwave (MW) and infrared (IR) estimates of precipitation has been an active area of research since past two decades. The anticipated launching of NASA's Global Precipitation Measurement (GPM) mission and the increasing number of spectral bands in recently launched geostationary platforms will provide greater opportunities for investigating new approaches to combine multi-source information towards improved global high resolution precipitation retrievals. After years of the communities' efforts the limitations of the existing techniques are: (1) Drawbacks of IR-only techniques to capture warm rainfall and screen out no-rain thin cirrus clouds; (2) Grid-box- only dependency of many algorithms with not much effort to capture the cloud textures whether in local or cloud patch scale; (3) Assumption of indirect relationship between rain rate and cloud-top temperature that force high intensity precipitation to any cold cloud; (4) Neglecting the dynamics and evolution of cloud in time; (5) Inconsistent combination of MW and IR-based precipitation estimations due to the combination strategies and as a result of above described shortcomings. This PhD dissertation attempts to improve the combination of data from Geostationary Earth Orbit (GEO) and Low-Earth Orbit (LEO) satellites in manners that will allow consistent high resolution integration of the more accurate precipitation estimates, directly observed through LEO's PMW sensors, into the short-term cloud evolution process, which can be inferred from GEO images. A set of novel approaches are introduced to cope with the listed limitations and is consist of the following four consecutive components: (1) starting with the GEO part and by using an artificial-neural network based method it is demonstrated that inclusion of multi-spectral data can ameliorate existing problems associated with IR-only precipitating retrievals; (2) through development of Precipitation Estimation

  10. Estimation of Stand Height and Forest Volume Using High Resolution Stereo Photography and Forest Type Map

    NASA Astrophysics Data System (ADS)

    Kim, K. M.

    2016-06-01

    Traditional field methods for measuring tree heights are often too costly and time consuming. An alternative remote sensing approach is to measure tree heights from digital stereo photographs which is more practical for forest managers and less expensive than LiDAR or synthetic aperture radar. This work proposes an estimation of stand height and forest volume(m3/ha) using normalized digital surface model (nDSM) from high resolution stereo photography (25cm resolution) and forest type map. The study area was located in Mt. Maehwa model forest in Hong Chun-Gun, South Korea. The forest type map has four attributes such as major species, age class, DBH class and crown density class by stand. Overlapping aerial photos were taken in September 2013 and digital surface model (DSM) was created by photogrammetric methods(aerial triangulation, digital image matching). Then, digital terrain model (DTM) was created by filtering DSM and subtracted DTM from DSM pixel by pixel, resulting in nDSM which represents object heights (buildings, trees, etc.). Two independent variables from nDSM were used to estimate forest stand volume: crown density (%) and stand height (m). First, crown density was calculated using canopy segmentation method considering live crown ratio. Next, stand height was produced by averaging individual tree heights in a stand using Esri's ArcGIS and the USDA Forest Service's FUSION software. Finally, stand volume was estimated and mapped using aerial photo stand volume equations by species which have two independent variables, crown density and stand height. South Korea has a historical imagery archive which can show forest change in 40 years of successful forest rehabilitation. For a future study, forest volume change map (1970s-present) will be produced using this stand volume estimation method and a historical imagery archive.

  11. Use of UAS Remote Sensing Data (AggieAir) to Estimate Crop ET at High Spatial Resolution

    NASA Astrophysics Data System (ADS)

    ELarab, M.; Torres, A.; Nieto Solana, H.; Kustas, W. P.; Song, L.; Alfieri, J. G.; Prueger, J. H.; McKee, L.; Anderson, M. C.; Jensen, A.; McKee, M.; Alsina, M. M.

    2015-12-01

    Estimation of the spatial distribution of evapotranspiration (ET) based on remotely sensed imagery has become useful for managing water in irrigated agricultural at various spatial scales. Currently, data acquired by conventional satellites (Landsat, ASTER, etc.) lack the needed spatial resolution to capture variability of interest to support evapotranspiration estimates. In this study, an unmanned aerial system (UAS), called AggieAirTM, was used to acquire high-resolution imagery in the visual, near infrared (0.15m resolution) and thermal infrared spectra (0.6m resolution). AggieAir flew over two study sites in Utah and Central Valley of California. The imagery was used as input to a surface energy balance model based on the Mapping Evapotranspiration with Internalized Calibration (METRIC) modeling approach. The discussion will highlight the ET estimation methodologies and the implications of having high resolution ET maps.

  12. A new impulsive seismic shear wave source for near-surface (0-30 m) seismic studies

    NASA Astrophysics Data System (ADS)

    Crane, J. M.; Lorenzo, J. M.

    2010-12-01

    Estimates of elastic moduli and fluid content in shallow (0-30 m) natural soils below artificial flood containment structures can be particularly useful in levee monitoring as well as seismic hazard studies. Shear wave moduli may be estimated from horizontally polarized, shear wave experiments. However, long profiles (>10 km) with dense receiver and shot spacings (<1m) cannot be collected efficiently using currently available shear wave sources. We develop a new, inexpensive, shear wave source for collecting fast, shot gathers over large acquisition sites. In particular, gas-charged, organic-rich sediments comprising most lower-delta sedimentary facies, greatly attenuate compressional body-waves. On the other hand, SH waves are relatively insensitive to pore-fluid moduli and can improve resolution. We develop a recoil device (Jolly, 1956) into a single-user, light-weight (<20 kg), impulsive, ground-surface-coupled SH wave generator, which is capable of working at rates of several hundred shotpoints per day. Older impulsive methods rely on hammer blows to ground-planted stationary targets. Our source is coupled to the ground with steel spikes and the powder charge can be detonated mechanically or electronically. Electrical fuses show repeatability in start times of < 50 microseconds. The barrel and shell-holder exceed required thicknesses to ensure complete safety during use. The breach confines a black-powder, 12-gauge shotgun shell, loaded with inert, environmentally safe ballast. In urban settings, produced heat and sound are confined by a detached, exterior cover. A moderate 2.5 g black-powder charge generates seismic amplitudes equivalent to three 4-kg sledge-hammer blows. We test this device to elucidate near subsurface sediment properties at former levee breach sites in New Orleans, Louisiana, USA. Our radio-telemetric seismic acquisition system uses an in-house landstreamer, consisting of 14-Hz horizontal component geophones, coupled to steel plates

  13. Dictionary-based probability density function estimation for high-resolution SAR data

    NASA Astrophysics Data System (ADS)

    Krylov, Vladimir; Moser, Gabriele; Serpico, Sebastiano B.; Zerubia, Josiane

    2009-02-01

    In the context of remotely sensed data analysis, a crucial problem is represented by the need to develop accurate models for the statistics of pixel intensities. In this work, we develop a parametric finite mixture model for the statistics of pixel intensities in high resolution synthetic aperture radar (SAR) images. This method is an extension of previously existing method for lower resolution images. The method integrates the stochastic expectation maximization (SEM) scheme and the method of log-cumulants (MoLC) with an automatic technique to select, for each mixture component, an optimal parametric model taken from a predefined dictionary of parametric probability density functions (pdf). The proposed dictionary consists of eight state-of-the-art SAR-specific pdfs: Nakagami, log-normal, generalized Gaussian Rayleigh, Heavy-tailed Rayleigh, Weibull, K-root, Fisher and generalized Gamma. The designed scheme is endowed with the novel initialization procedure and the algorithm to automatically estimate the optimal number of mixture components. The experimental results with a set of several high resolution COSMO-SkyMed images demonstrate the high accuracy of the designed algorithm, both from the viewpoint of a visual comparison of the histograms, and from the viewpoint of quantitive accuracy measures such as correlation coefficient (above 99,5%). The method proves to be effective on all the considered images, remaining accurate for multimodal and highly heterogeneous scenes.

  14. Assessment of radar resolution requirements for soil moisture estimation from simulated satellite imagery. [Kansas

    NASA Technical Reports Server (NTRS)

    Ulaby, F. T. (Principal Investigator); Dobson, M. C.; Moezzi, S.

    1982-01-01

    Radar simulations were performed at five-day intervals over a twenty-day period and used to estimate soil moisture from a generalized algorithm requiring only received power and the mean elevation of a test site near Lawrence, Kansas. The results demonstrate that the soil moisture of about 90% of the 20-m by 20-m pixel elements can be predicted with an accuracy of + or - 20% of field capacity within relatively flat agricultural portions of the test site. Radar resolutions of 93 m by 100 m with 23 looks or coarser gave the best results, largely because of the effects of signal fading. For the distribution of land cover categories, soils, and elevation in the test site, very coarse radar resolutions of 1 km by 1 km and 2.6 km by 3.1 km gave the best results for wet moisture conditions while a finer resolution of 93 m by 100 m was found to yield superior results for dry to moist soil conditions.

  15. Experimental Estimation of CLASP Spatial Resolution: Results of the Instrument's Optical Alignment

    NASA Technical Reports Server (NTRS)

    Giono, Gabrial; Katsukawa, Yukio; Ishikawa, Ryoko; Narukage, Noriyuki; Bando, Takamasa; Kano, Ryohei; Suematsu, Yoshinori; Kobayashi, Ken; Winebarger, Amy; Auchere, Frederic

    2015-01-01

    The Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP) is a sounding-rocket experiment currently being built at the National Astronomical Observatory of Japan. This instrument aims to probe for the first time the magnetic field strength and orientation in the solar upper-chromosphere and lower-transition region. CLASP will measure the polarization of the Lyman-Alpha line (121.6nm) with an unprecedented accuracy, and derive the magnetic field information through the Hanle effect. Although polarization accuracy and spectral resolution are crucial for the Hanle effect detection, spatial resolution is also important to get reliable context image via the slit-jaw camera. As spatial resolution is directly related with the alignment of optics, it is also a good way of ensuring the alignment of the instrument to meet the scientific requirement. This poster will detail the experiments carried out to align CLASP's optics (telescope and spectrograph), as both part of the instrument were aligned separately. The telescope was aligned in double-pass mode, and a laser interferometer (He-Ne) was used to measure the telescope's wavefront error (WFE). The secondary mirror tilt and position were adjusted to remove comas and defocus aberrations from the WFE. Effect of gravity on the WFE measurement was estimated and the final WFE derived in zero-g condition for CLASP telescope will be presented. In addition, an estimation of the spot shape and size derived from the final WFE will also be shown. The spectrograph was aligned with a custom procedure: because Ly-??light is absorbed by air, the spectrograph's off-axis parabolic mirrors were aligned in Visible Light (VL) using a custom-made VL grating instead of the flight Ly-? grating. Results of the alignment in Visible Light will be shown and the spot shape recorded with CCDs at various position along the slit will be displayed. Results from both alignment experiment will be compared to the design requirement, and will be combined in

  16. Surprises from stream greenhouse gas emissions estimated at high resolution in a catchment

    NASA Astrophysics Data System (ADS)

    Natchimuthu, Sivakiruthika; Wallin, Marcus; Klemedtsson, Leif; Bastviken, David

    2016-04-01

    Streams represent environments where terrestrial and aquatic habitats meet and has recently been recognized as disproportionally large emitters of CO2 in landscapes. However, previous estimates are often based on measurements with low resolution in time and space, and frequently CO2 concentrations are also estimated indirectly from alkalinity and pH measurements adding to the uncertainty. The capacity of streams to emit CH4 is presently also poorly understood. In this study, we performed regular and spatially distributed measurements of CO2 and CH4 water concentrations and gas exchange rates in a headwater stream network, aiming to resolve spatial and temporal variability in flux patterns. Multiple supplementary methods including tracer injections, CO2 sensor networks, drifting flux chambers, and stream section mass balances were performed. A locally validated spatiotemporal model with high accuracy and resolution was developed. The observed variability was high revealing high fluxes very locally or during short periods in time related to rapid hydrological events, highlighting the need to consider spatiotemporal variability in detail. Stream CH4 emissions were also surprisingly high compared to CO2 emissions.

  17. Impact of temporal resolution on estimating capillary RBC-flux with optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Li, Baoqiang; Wang, Hui; Fu, Buyin; Wang, Ruopeng; Sakadžić, Sava; Boas, David A.

    2017-01-01

    Optical coherence tomography (OCT) has been used to measure capillary red blood cell (RBC) flux. However, one important technical issue is that the accuracy of this method is subject to the temporal resolution (Δt) of the repeated RBC-passage B-scans. A ceiling effect arises due to an insufficient Δt limiting the maximum RBC-flux that can be measured. In this letter, we first present simulations demonstrating that Δt=1.5 ms permits measuring RBC-flux up to 150 RBCs/s with an underestimation of 9%. The simulations further show that measurements with Δt=3 and 4.5 ms provide relatively less accurate estimates for typical physiological fluxes. We provide experimental data confirming the simulation results showing that reduced temporal resolution (i.e., a longer Δt) results in an underestimation of mean flux and compresses the distribution of measured fluxes, which potentially confounds physiological interpretation of the results. The results also apply to RBC-passage measurements made with confocal and two-photon microscopy for estimating capillary RBC-flux.

  18. A multi-resolution multi-size-windows disparity estimation approach

    NASA Astrophysics Data System (ADS)

    Martinez Bauza, Judit; Shiralkar, Manish

    2011-03-01

    This paper describes an algorithm for estimating the disparity between 2 images of a stereo pair. The disparity is related to the depth of the objects in the scene. Being able to obtain the depth of the objects in the scene is useful in many applications such as virtual reality, 3D user interfaces, background-foreground segmentation, or depth-image-based synthesis. This last application has motivated the proposed algorithm as part of a system that estimates disparities from a stereo pair and synthesizes new views. Synthesizing virtual views enables the post-processing of 3D content to adapt to user preferences or viewing conditions, as well as enabling the interface with multi-view auto-stereoscopic displays. The proposed algorithm has been designed to fulfill the following constraints: (a) low memory requirements, (b) local and parallelizable processing, and (c) adaptability to a sudden reduction in processing resources. Our solution uses a multi-resolution multi-size-windows approach, implemented as a line-independent process, well-suited for GPU implementation. The multi-resolution approach provides adaptability to sudden reduction in processing capabilities, besides computational advantages; the windows-based image processing algorithm guarantees low-memory requirements and local processing.

  19. Efficient High-Rate Satellite Clock Estimation for PPP Ambiguity Resolution Using Carrier-Ranges

    PubMed Central

    Chen, Hua; Jiang, Weiping; Ge, Maorong; Wickert, Jens; Schuh, Harald

    2014-01-01

    In order to catch up the short-term clock variation of GNSS satellites, clock corrections must be estimated and updated at a high-rate for Precise Point Positioning (PPP). This estimation is already very time-consuming for the GPS constellation only as a great number of ambiguities need to be simultaneously estimated. However, on the one hand better estimates are expected by including more stations, and on the other hand satellites from different GNSS systems must be processed integratively for a reliable multi-GNSS positioning service. To alleviate the heavy computational burden, epoch-differenced observations are always employed where ambiguities are eliminated. As the epoch-differenced method can only derive temporal clock changes which have to be aligned to the absolute clocks but always in a rather complicated way, in this paper, an efficient method for high-rate clock estimation is proposed using the concept of “carrier-range” realized by means of PPP with integer ambiguity resolution. Processing procedures for both post- and real-time processing are developed, respectively. The experimental validation shows that the computation time could be reduced to about one sixth of that of the existing methods for post-processing and less than 1 s for processing a single epoch of a network with about 200 stations in real-time mode after all ambiguities are fixed. This confirms that the proposed processing strategy will enable the high-rate clock estimation for future multi-GNSS networks in post-processing and possibly also in real-time mode. PMID:25429413

  20. Efficient high-rate satellite clock estimation for PPP ambiguity resolution using carrier-ranges.

    PubMed

    Chen, Hua; Jiang, Weiping; Ge, Maorong; Wickert, Jens; Schuh, Harald

    2014-11-25

    In order to catch up the short-term clock variation of GNSS satellites, clock corrections must be estimated and updated at a high-rate for Precise Point Positioning (PPP). This estimation is already very time-consuming for the GPS constellation only as a great number of ambiguities need to be simultaneously estimated. However, on the one hand better estimates are expected by including more stations, and on the other hand satellites from different GNSS systems must be processed integratively for a reliable multi-GNSS positioning service. To alleviate the heavy computational burden, epoch-differenced observations are always employed where ambiguities are eliminated. As the epoch-differenced method can only derive temporal clock changes which have to be aligned to the absolute clocks but always in a rather complicated way, in this paper, an efficient method for high-rate clock estimation is proposed using the concept of "carrier-range" realized by means of PPP with integer ambiguity resolution. Processing procedures for both post- and real-time processing are developed, respectively. The experimental validation shows that the computation time could be reduced to about one sixth of that of the existing methods for post-processing and less than 1 s for processing a single epoch of a network with about 200 stations in real-time mode after all ambiguities are fixed. This confirms that the proposed processing strategy will enable the high-rate clock estimation for future multi-GNSS networks in post-processing and possibly also in real-time mode.

  1. Projections onto Convex Sets Super-Resolution Reconstruction Based on Point Spread Function Estimation of Low-Resolution Remote Sensing Images

    PubMed Central

    Fan, Chong; Wu, Chaoyun; Li, Grand; Ma, Jun

    2017-01-01

    To solve the problem on inaccuracy when estimating the point spread function (PSF) of the ideal original image in traditional projection onto convex set (POCS) super-resolution (SR) reconstruction, this paper presents an improved POCS SR algorithm based on PSF estimation of low-resolution (LR) remote sensing images. The proposed algorithm can improve the spatial resolution of the image and benefit agricultural crop visual interpolation. The PSF of the high-resolution (HR) image is unknown in reality. Therefore, analysis of the relationship between the PSF of the HR image and the PSF of the LR image is important to estimate the PSF of the HR image by using multiple LR images. In this study, the linear relationship between the PSFs of the HR and LR images can be proven. In addition, the novel slant knife-edge method is employed, which can improve the accuracy of the PSF estimation of LR images. Finally, the proposed method is applied to reconstruct airborne digital sensor 40 (ADS40) three-line array images and the overlapped areas of two adjacent GF-2 images by embedding the estimated PSF of the HR image to the original POCS SR algorithm. Experimental results show that the proposed method yields higher quality of reconstructed images than that produced by the blind SR method and the bicubic interpolation method. PMID:28208837

  2. A sparse reconstruction method for the estimation of multi-resolution emission fields via atmospheric inversion

    DOE PAGES

    Ray, J.; Lee, J.; Yadav, V.; ...

    2015-04-29

    Atmospheric inversions are frequently used to estimate fluxes of atmospheric greenhouse gases (e.g., biospheric CO2 flux fields) at Earth's surface. These inversions typically assume that flux departures from a prior model are spatially smoothly varying, which are then modeled using a multi-variate Gaussian. When the field being estimated is spatially rough, multi-variate Gaussian models are difficult to construct and a wavelet-based field model may be more suitable. Unfortunately, such models are very high dimensional and are most conveniently used when the estimation method can simultaneously perform data-driven model simplification (removal of model parameters that cannot be reliably estimated) and fitting.more » Such sparse reconstruction methods are typically not used in atmospheric inversions. In this work, we devise a sparse reconstruction method, and illustrate it in an idealized atmospheric inversion problem for the estimation of fossil fuel CO2 (ffCO2) emissions in the lower 48 states of the USA. Our new method is based on stagewise orthogonal matching pursuit (StOMP), a method used to reconstruct compressively sensed images. Our adaptations bestow three properties to the sparse reconstruction procedure which are useful in atmospheric inversions. We have modified StOMP to incorporate prior information on the emission field being estimated and to enforce non-negativity on the estimated field. Finally, though based on wavelets, our method allows for the estimation of fields in non-rectangular geometries, e.g., emission fields inside geographical and political boundaries. Our idealized inversions use a recently developed multi-resolution (i.e., wavelet-based) random field model developed for ffCO2 emissions and synthetic observations of ffCO2 concentrations from a limited set of measurement sites. We find that our method for limiting the estimated field within an irregularly shaped region is about a factor of 10 faster than conventional approaches. It also

  3. Experimental High Resolution (3 km) SMAP Soil Moisture Data Fields With Uncertainty Estimates

    NASA Astrophysics Data System (ADS)

    Das, N. N.

    2015-12-01

    NASA's Soil Moisture Active Passive (SMAP) mission was launched on January 31st, 2015. The objective of the mission is global mapping of surface soil moisture and landscape freeze/thaw state. SMAP utilizes an L-band radar and radiometer sharing a rotating 6-meter mesh reflector antenna. The SMAP spacecraft is in a 685-km Sun-synchronous near-polar orbit, and viewing the surface at a constant 40-degree incidence angle with a 1000-km swath width. Merging of the high-resolution active (radar) and coarse-resolution but high-sensitivity passive (radiometer) L-band observations enable an unprecedented combination of accuracy, resolution, coverage and revisit-time for soil moisture and freeze/thaw state retrievals. However, on July 7th, 2015, the SMAP radar encountered an anomaly and is currently inoperable. Efforts are being made to revive the SMAP radar. Due to the present status of the SMAP observatory, nearly ~2.5 months (from the end of In-Orbit-Check April 13th, 2015 to July 7th, 2015) of the SMAP Active Passive product will be available to public through the NASA DAAC at National Snow and Ice Data Center (NSIDC). The baseline L2_SM_AP product is retrieved soil moisture from the disaggregated/downscaled brightness temperature obtained by merging the coarse-resolution (~36 km) radiometer brightness temperature data and the high-resolution (~3 km) radar backscatter data. The baseline product is intermediate scale 9 km global soil moisture information. Experimentally, a much higher resolution global surface soil moisture data set is also produced at 3 km. This experimental product covering the 2.5 Spring/Summer months is the focus of this presentation. We specifically focus on the analysis of errors and reliability of this data set. The errors in disaggregated brightness temperatures and the retrived soil moisture estimates are discussed. In the presentation the accuracies of the SMAP L2-SM_AP soil moisture retrievals will be shown using summary comparisons with in

  4. Paleomagnetic and rock magnetic study of IODP Site U1408 in the Northwest Atlantic - toward the high-resolution relative paleointensity estimate during the middle Eocene

    NASA Astrophysics Data System (ADS)

    Yamamoto, Y.; Yamazaki, T.; Oda, H.

    2015-12-01

    We have conducted paleomagnetic and rock magnetic measurements on the sedimentary sections recovered from Integrated Ocean Drilling Program (IODP) Site U1408 in the Northwest Atlantic, off Newfoundland. The measurements were done on u-channel samples using a pass-through superconducting rock magnetometer in a manner that remanent magnetizations (natural, anhysteretic and isothermal remanent magnetizations: NRM, ARM and IRM) were subjected to stepwise alternating field (AF) demagnetizations up to 80 mT and are measured with 1 cm spacing at each step.The characteristic remanent magnetization (ChRM) was resolved after AF demagnetization of 20-30 mT for most of the studied interval. As a result, we could identify several polarity reversals which were able to be correlated with the geomagnetic polarity time scale by Gradstein et al. (2012) (Geologic Time Scale 2012), with referring the shipboard biostratigraphy (Norris et al., 2014). The interval at ~ 33-157 mcd (meter composite depth) was interpreted to cover the Chrons C18n.1n to C20n with missing Chron C19n because of the somewhat ambiguous magnetic signals at the interval at ~ 70-110 mcd. The correlation provided an age model inferring sedimentation rate of about 2-4 cm/kyr during these chrons.There is the interval that shows relatively constant ARM and IRM intensities as well as ratios of ARM to IRM (ARM/IRM): the interval at ~ 37-90 mcd resulted in ARM intensity of 0.2-0.4 A/m, IRM intensity of 1-2 A/m and ARM/IRM of 0.17-0.20. This interval corresponds to the Chron C18 and the estimated sedimentation rate of the interval is ~ 2 cm/kyr. It is expected that high-resolution relative paleointensity estimate during the middle Eocene is potentially possible. We will report a preliminary estimate.

  5. River discharge estimation at daily resolution from satellite altimetry over an entire river basin

    NASA Astrophysics Data System (ADS)

    Tourian, M. J.; Schwatke, C.; Sneeuw, N.

    2017-03-01

    One of the main challenges of hydrological modeling is the poor spatiotemporal coverage of in situ discharge databases which have steadily been declining over the past few decades. It has been demonstrated that water heights over rivers from satellite altimetry can sensibly be used to deal with the growing lack of in situ discharge data. However, the altimetric discharge is often estimated from a single virtual station suffering from coarse temporal resolution, sometimes with data outages, poor modeling and inconsistent sampling. In this study, we propose a method to estimate daily river discharge using altimetric time series of an entire river basin including its tributaries. Here, we implement a linear dynamic model to (1) provide a scheme for data assimilation of multiple altimetric discharge along a river; (2) estimate daily discharge; (3) deal with data outages, and (4) smooth the estimated discharge. The model consists of a stochastic process model that benefits from the cyclostationary behavior of discharge. Our process model comprises the covariance and cross-covariance information of river discharge at different gauges. Combined with altimetric discharge time series, we solve the linear dynamic system using the Kalman filter and smoother providing unbiased discharge with minimum variance. We evaluate our method over the Niger basin, where we generate altimetric discharge using water level time series derived from missions ENVISAT, SARAL/AltiKa, and Jason-2. Validation against in situ discharge shows that our method provides daily river discharge with an average correlation of 0.95, relative RMS error of 12%, relative bias of 10% and NSE coefficient of 0.7. Using a modified NSE-metric, that assesses the non-cyclostationary behavior, we show that our estimated discharge outperforms available legacy mean daily discharge.

  6. High-resolution property-based flood damage estimation: how should urban topography be represented?

    NASA Astrophysics Data System (ADS)

    O'Neill, J.; Yu, D.; Wilby, R. L.; Bosher, L.

    2012-12-01

    High-resolution property-based flood damage estimation: how should urban topography be represented? The cost of damage caused by flooding to property in the UK has increased by 200% decade on decade, from £1.5 billion (1990 - 2000) to £4.5 billion (2000 - 2010) (ABI 2010). This is widely predicted to increase further in the coming decades (Huntington 2006). Flood damage estimation to residential buildings is typically undertaken by coupling vulnerability curves with flow variables obtained from hydraulic modelling. Recent advances in urban flood inundation modelling provide good estimations of flood depth for damage estimation. However, the approaches to the representation of buildings in urban flood inundation modelling require further investigation as this affects the depth prediction which in turn will determine the accuracy of damage estimation. This study evaluates the effects of different approaches to the representation of buildings in urban topography on damage estimation. A case study was undertaken in Cockermouth of the English Lake District, with primary data collected during the November 2009 event to validate both the hydraulic modelling and damage estimation. A 2D inertia-based hydraulic model was used and the prediction was coupled with the standard vulnerability curves for the UK. Three approaches to the representation of buildings in urban topography were investigated: (i) a bare ground Digital Terrain Model with no explicit representation of buildings (DTM); (ii) explicit representation of buildings with impermeable blocks (BLOCKAGE); and (iii) representation of buildings with threshold levels (THRESHOLD). Results were compared with the observed inundation extent and discrete point depths. In terms of inundation extent, the DTM and THRESHOLD approach produced the best estimate. With the BLOCKAGE approach, the extent of water is less well predicted due to the blockage effect of the buildings which effectively act as flow barriers. Depth was best

  7. Improving estimation of microseismic focal mechanisms using a high-resolution velocity model

    NASA Astrophysics Data System (ADS)

    Chen, T.; Chen, Y.; Lin, Y.; Huang, L.

    2015-12-01

    Injection and migration of CO2 during the geological carbon sequestration change the pore pressure and stress distribution in the reservoir. The change in stress may induce brittle failure on fractures, causing microseismic events. Focal mechanisms of induced microseismic events are useful for understanding stress evolution in the reservoir. An accurate estimation of microseismic focal mechanism depends on the accuracy of velocity models. In this work, we study the improvement on estimation of microseismic focal mechanisms using a high-resolution velocity model. We obtain the velocity model using a velocity inversion algorithm with a modified total-variation scheme rather than the commonly used Tikhonov regularization technique. We demonstrate with synthetic microseismic data that the velocity inversion method with a modified total-variation regularization scheme improves velocity inversion, and the improved velocity models enhance the accuracy of estimated focal mechanisms of microseismic events. We apply the new methodology to microseismic data acquired at a CO2-EOR (enhanced oil recovery) site at Aneth, Utah.

  8. Super-resolution spectral estimation in short-time non-contact vital sign measurement

    NASA Astrophysics Data System (ADS)

    Sun, Li; Li, Yusheng; Hong, Hong; Xi, Feng; Cai, Weidong; Zhu, Xiaohua

    2015-04-01

    Non-contact techniques for measuring vital signs attract great interest due to the benefits shown in medical monitoring, military application, etc. However, the presence of respiration harmonics caused by nonlinear phase modulation will result in performance degradation. Suffering from smearing and leakage problems, conventional discrete Fourier transform (DFT) based methods cannot distinguish the heartbeat component from closely located respiration harmonics in frequency domain, especially in short-time processing. In this paper, the theory of sparse reconstruction is merged with an extended harmonic model of vital signals, aiming at achieving a super-resolution spectral estimation of vital signals by additionally exploiting the inherent sparse prior information. Both simulated and experimental results show that the proposed algorithm has superior performance to DFT-based methods and the recently applied multiple signal classification algorithm, and the required processing window length has been shortened to 5.12 s.

  9. Incorporating Hydrologic Insight into Geophysical Inversion: Resolution Limitations and Direct Estimation of Solute Plume Moments

    NASA Astrophysics Data System (ADS)

    Day-Lewis, F. D.; Singha, K.; Pidlisecky, A.

    2005-12-01

    Time-lapse geophysical tomography (e.g., electrical resistivity and radar) can provide valuable insights into hydrologic phenomena, including tracer transport, aquifer dynamics, and engineered remediation. Tomograms have been used to infer the spatial and temporal moments of solute plumes for model development and calibration. The reliability of inferred moment values is limited by tomographic resolution, which is a function of survey geometry, measurement physics, measurement error, and inverse problem parameterization and regularization. Here, we (1) assess the resolution-dependent reliability of moment inference based on results from conventional pixel-based inversion with Tikhanov-style regularization; and (2) investigate alternative parameterization/regularization techniques that capitalize on hydrologic insight to produce more reliable moment estimates. Conventional pixel-based parameterization and regularization criteria yield the simplest solution that satisfies the data, where solution simplicity is measured by deviations from a prior mean and/or the norm of the first or second spatial derivative (flatness and smoothness, respectively) between adjacent pixels. While effective for static imaging of large-scale geologic or aquifer structure, these measures of simplicity may be less appropriate for imaging transient hydrologic processes and non-stationary targets such as solute plumes. For underdetermined problems, tomograms may overpredict the extent and underpredict the magnitude of target plumes. We contend that, at best, conventional regularization criteria do not capitalize on valuable hydrologic information, such as the total mass of injected fluid or solute; at worst they are inconsistent with the physics underlying the transport process of interest and may lead to misleading estimates of plume moments. We explore strategies to incorporate hydrologic insight into tomographic inversion for time-lapse hydrologic monitoring: moment-based tomographic

  10. High-resolution Neogene and Quaternary estimates of Nubia-Eurasia-North America Plate motion

    NASA Astrophysics Data System (ADS)

    DeMets, C.; Iaffaldano, G.; Merkouriev, S.

    2015-10-01

    Reconstructions of the history of convergence between the Nubia and Eurasia plates constitute an important part of a broader framework for understanding deformation in the Mediterranean region and the closing of the Mediterranean Basin. Herein, we combine high-resolution reconstructions of Eurasia-North America and Nubia-North America Plate motions to determine rotations that describe Nubia-Eurasia Plate motion at ˜1 Myr intervals for the past 20 Myr. We apply trans-dimensional hierarchical Bayesian inference to the Eurasia-North America and Nubia-North America rotation sequences in order to reduce noise in the newly estimated Nubia-Eurasia rotations. The noise-reduced rotation sequences for the Eurasia-North America and Nubia-North America Plate pairs describe remarkably similar kinematic histories since 20 Ma, consisting of relatively steady seafloor spreading from 20 to 8 Ma, ˜20 per cent opening-rate slowdowns at 8-6.5 Ma, and steady plate motion from ˜7 Ma to the present. Our newly estimated Nubia-Eurasia rotations predict that convergence across the central Mediterranean Sea slowed by ˜50 per cent and rotated anticlockwise after ˜25 Ma until 13 Ma. Motion since 13 Ma has remained relatively steady. An absence of evidence for a significant change in motion immediately before or during the Messinian Salinity Crisis at 6.3-5.6 Ma argues against a change in plate motion as its causative factor. The detachment of the Arabian Peninsula from Africa at 30-24 Ma may have triggered the convergence rate slowdown before 13 Ma; however, published reconstructions of Nubia-Eurasia motion for times before 20 Ma are too widely spaced to determine with confidence whether the two are correlated. A significant discrepancy between our new estimates of Nubia-Eurasia motion during the past few Myr and geodetic estimates calls for further investigation.

  11. A tool for rapid post-hurricane urban tree debris estimates using high resolution aerial imagery

    NASA Astrophysics Data System (ADS)

    Szantoi, Zoltan; Malone, Sparkle; Escobedo, Francisco; Misas, Orlando; Smith, Scot; Dewitt, Bon

    2012-08-01

    Coastal communities in the southeast United States have regularly experienced severe hurricane impacts. To better facilitate recovery efforts in these communities following natural disasters, state and federal agencies must respond quickly with information regarding the extent and severity of hurricane damage and the amount of tree debris volume. A tool was developed to detect downed trees and debris volume to better aid disaster response efforts and tree debris removal. The tool estimates downed tree debris volume in hurricane affected urban areas using a Leica Airborne Digital Sensor (ADS40) and very high resolution digital images. The tool employs a Sobel edge detection algorithm combined with spectral information based on color filtering using 15 different statistical combinations of spectral bands. The algorithm identified downed tree edges based on contrasts between tree stems, grass, and asphalt and color filtering was then used to establish threshold values. Colors outside these threshold values were replaced and excluded from the detection processes. Results were overlaid and an "edge line" was placed where lines or edges from longer consecutive segments and color values within the threshold were met. Where two lines were paired within a very short distance in the scene a polygon was drawn automatically and, in doing so, downed tree stems were detected. Tree stem diameter-volume bulking factors were used to estimate post-hurricane tree debris volumes. Images following Hurricane Ivan in 2005 and Hurricane Ike in 2008 were used to assess the error of the tool by comparing downed tree counts and subsequent debris volume estimates with post-hurricane photo-interpreted downed tree counts and actual field measured estimates of downed tree debris volume. The errors associated with the use of the tool and potential applications are also presented.

  12. Projections onto Convex Sets Super-Resolution Reconstruction Based on Point Spread Function Estimation of Low-Resolution Remote Sensing Images.

    PubMed

    Fan, Chong; Wu, Chaoyun; Li, Grand; Ma, Jun

    2017-02-13

    To solve the problem on inaccuracy when estimating the point spread function (PSF) of the ideal original image in traditional projection onto convex set (POCS) super-resolution (SR) reconstruction, this paper presents an improved POCS SR algorithm based on PSF estimation of low-resolution (LR) remote sensing images. The proposed algorithm can improve the spatial resolution of the image and benefit agricultural crop visual interpolation. The PSF of the highresolution (HR) image is unknown in reality. Therefore, analysis of the relationship between the PSF of the HR image and the PSF of the LR image is important to estimate the PSF of the HR image by using multiple LR images. In this study, the linear relationship between the PSFs of the HR and LR images can be proven. In addition, the novel slant knife-edge method is employed, which can improve the accuracy of the PSF estimation of LR images. Finally, the proposed method is applied to reconstruct airborne digital sensor 40 (ADS40) three-line array images and the overlapped areas of two adjacent GF-2 images by embedding the estimated PSF of the HR image to the original POCS SR algorithm. Experimental results show that the proposed method yields higher quality of reconstructed images than that produced by the blind SR method and the bicubic interpolation method.

  13. Large scale IRAM 30 m CO-observations in the giant molecular cloud complex W43

    NASA Astrophysics Data System (ADS)

    Carlhoff, P.; Nguyen Luong, Q.; Schilke, P.; Motte, F.; Schneider, N.; Beuther, H.; Bontemps, S.; Heitsch, F.; Hill, T.; Kramer, C.; Ossenkopf, V.; Schuller, F.; Simon, R.; Wyrowski, F.

    2013-12-01

    We aim to fully describe the distribution and location of dense molecular clouds in the giant molecular cloud complex W43. It was previously identified as one of the most massive star-forming regions in our Galaxy. To trace the moderately dense molecular clouds in the W43 region, we initiated W43-HERO, a large program using the IRAM 30 m telescope, which covers a wide dynamic range of scales from 0.3 to 140 pc. We obtained on-the-fly-maps in 13CO (2-1) and C18O (2-1) with a high spectral resolution of 0.1 km s-1 and a spatial resolution of 12''. These maps cover an area of ~1.5 square degrees and include the two main clouds of W43 and the lower density gas surrounding them. A comparison to Galactic models and previous distance calculations confirms the location of W43 near the tangential point of the Scutum arm at approximately 6 kpc from the Sun. The resulting intensity cubes of the observed region are separated into subcubes, which are centered on single clouds and then analyzed in detail. The optical depth, excitation temperature, and H2 column density maps are derived out of the 13CO and C18O data. These results are then compared to those derived from Herschel dust maps. The mass of a typical cloud is several 104 M⊙ while the total mass in the dense molecular gas (>102 cm-3) in W43 is found to be ~1.9 × 106 M⊙. Probability distribution functions obtained from column density maps derived from molecular line data and Herschel imaging show a log-normal distribution for low column densities and a power-law tail for high densities. A flatter slope for the molecular line data probability distribution function may imply that those selectively show the gravitationally collapsing gas. Appendices are available in electronic form at http://www.aanda.orgThe final datacubes (13CO and C18O) for the entire survey are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/560/A24

  14. ELM: AN ALGORITHM TO ESTIMATE THE ALPHA ABUNDANCE FROM LOW-RESOLUTION SPECTRA

    SciTech Connect

    Bu, Yude; Zhao, Gang; Kumar, Yerra Bharat; Pan, Jingchang E-mail: gzhao@nao.cas.cn

    2016-01-20

    We have investigated a novel methodology using the extreme learning machine (ELM) algorithm to determine the α abundance of stars. Applying two methods based on the ELM algorithm—ELM+spectra and ELM+Lick indices—to the stellar spectra from the ELODIE database, we measured the α abundance with a precision better than 0.065 dex. By applying these two methods to the spectra with different signal-to-noise ratios (S/Ns) and different resolutions, we found that ELM+spectra is more robust against degraded resolution and ELM+Lick indices is more robust against variation in S/N. To further validate the performance of ELM, we applied ELM+spectra and ELM+Lick indices to SDSS spectra and estimated α abundances with a precision around 0.10 dex, which is comparable to the results given by the SEGUE Stellar Parameter Pipeline. We further applied ELM to the spectra of stars in Galactic globular clusters (M15, M13, M71) and open clusters (NGC 2420, M67, NGC 6791), and results show good agreement with previous studies (within 1σ). A comparison of the ELM with other widely used methods including support vector machine, Gaussian process regression, artificial neural networks, and linear least-squares regression shows that ELM is efficient with computational resources and more accurate than other methods.

  15. Estimation of the Distribution of Tabebuia guayacan (Bignoniaceae) Using High-Resolution Remote Sensing Imagery

    PubMed Central

    Sánchez-Azofeifa, Arturo; Rivard, Benoit; Wright, Joseph; Feng, Ji-Lu; Li, Peijun; Chong, Mei Mei; Bohlman, Stephanie A.

    2011-01-01

    Species identification and characterization in tropical environments is an emerging field in tropical remote sensing. Significant efforts are currently aimed at the detection of tree species, of levels of forest successional stages, and the extent of liana occurrence at the top of canopies. In this paper we describe our use of high resolution imagery from the Quickbird Satellite to estimate the flowering population of Tabebuia guayacan trees at Barro Colorado Island (BCI), in Panama. The imagery was acquired on 29 April 2002 and 21 March 2004. Spectral Angle Mapping via a One-Class Support Vector machine was used to detect the presence of 422 and 557 flowering tress in the April 2002 and March 2004 imagery. Of these, 273 flowering trees are common to both dates. This study presents a new perspective on the effectiveness of high resolution remote sensing for monitoring a phenological response and its use as a tool for potential conservation and management of natural resources in tropical environments. PMID:22163825

  16. ELM: an Algorithm to Estimate the Alpha Abundance from Low-resolution Spectra

    NASA Astrophysics Data System (ADS)

    Bu, Yude; Zhao, Gang; Pan, Jingchang; Bharat Kumar, Yerra

    2016-01-01

    We have investigated a novel methodology using the extreme learning machine (ELM) algorithm to determine the α abundance of stars. Applying two methods based on the ELM algorithm—ELM+spectra and ELM+Lick indices—to the stellar spectra from the ELODIE database, we measured the α abundance with a precision better than 0.065 dex. By applying these two methods to the spectra with different signal-to-noise ratios (S/Ns) and different resolutions, we found that ELM+spectra is more robust against degraded resolution and ELM+Lick indices is more robust against variation in S/N. To further validate the performance of ELM, we applied ELM+spectra and ELM+Lick indices to SDSS spectra and estimated α abundances with a precision around 0.10 dex, which is comparable to the results given by the SEGUE Stellar Parameter Pipeline. We further applied ELM to the spectra of stars in Galactic globular clusters (M15, M13, M71) and open clusters (NGC 2420, M67, NGC 6791), and results show good agreement with previous studies (within 1σ). A comparison of the ELM with other widely used methods including support vector machine, Gaussian process regression, artificial neural networks, and linear least-squares regression shows that ELM is efficient with computational resources and more accurate than other methods.

  17. Estimating babassu palm density using automatic palm tree detection with very high spatial resolution satellite images.

    PubMed

    Dos Santos, Alessio Moreira; Mitja, Danielle; Delaître, Eric; Demagistri, Laurent; de Souza Miranda, Izildinha; Libourel, Thérèse; Petit, Michel

    2017-05-15

    High spatial resolution images as well as image processing and object detection algorithms are recent technologies that aid the study of biodiversity and commercial plantations of forest species. This paper seeks to contribute knowledge regarding the use of these technologies by studying randomly dispersed native palm tree. Here, we analyze the automatic detection of large circular crown (LCC) palm tree using a high spatial resolution panchromatic GeoEye image (0.50 m) taken on the area of a community of small agricultural farms in the Brazilian Amazon. We also propose auxiliary methods to estimate the density of the LCC palm tree Attalea speciosa (babassu) based on the detection results. We used the "Compt-palm" algorithm based on the detection of palm tree shadows in open areas via mathematical morphology techniques and the spatial information was validated using field methods (i.e. structural census and georeferencing). The algorithm recognized individuals in life stages 5 and 6, and the extraction percentage, branching factor and quality percentage factors were used to evaluate its performance. A principal components analysis showed that the structure of the studied species differs from other species. Approximately 96% of the babassu individuals in stage 6 were detected. These individuals had significantly smaller stipes than the undetected ones. In turn, 60% of the stage 5 babassu individuals were detected, showing significantly a different total height and a different number of leaves from the undetected ones. Our calculations regarding resource availability indicate that 6870 ha contained 25,015 adult babassu palm tree, with an annual potential productivity of 27.4 t of almond oil. The detection of LCC palm tree and the implementation of auxiliary field methods to estimate babassu density is an important first step to monitor this industry resource that is extremely important to the Brazilian economy and thousands of families over a large scale.

  18. Estimating global and North American methane emissions with high spatial resolution using GOSAT satellite data

    NASA Astrophysics Data System (ADS)

    Turner, A. J.; Jacob, D. J.; Wecht, K. J.; Maasakkers, J. D.; Lundgren, E.; Andrews, A. E.; Biraud, S. C.; Boesch, H.; Bowman, K. W.; Deutscher, N. M.; Dubey, M. K.; Griffith, D. W. T.; Hase, F.; Kuze, A.; Notholt, J.; Ohyama, H.; Parker, R.; Payne, V. H.; Sussmann, R.; Sweeney, C.; Velazco, V. A.; Warneke, T.; Wennberg, P. O.; Wunch, D.

    2015-06-01

    We use 2009-2011 space-borne methane observations from the Greenhouse Gases Observing SATellite (GOSAT) to estimate global and North American methane emissions with 4° × 5° and up to 50 km × 50 km spatial resolution, respectively. GEOS-Chem and GOSAT data are first evaluated with atmospheric methane observations from surface and tower networks (NOAA/ESRL, TCCON) and aircraft (NOAA/ESRL, HIPPO), using the GEOS-Chem chemical transport model as a platform to facilitate comparison of GOSAT with in situ data. This identifies a high-latitude bias between the GOSAT data and GEOS-Chem that we correct via quadratic regression. Our global adjoint-based inversion yields a total methane source of 539 Tg a-1 with some important regional corrections to the EDGARv4.2 inventory used as a prior. Results serve as dynamic boundary conditions for an analytical inversion of North American methane emissions using radial basis functions to achieve high resolution of large sources and provide error characterization. We infer a US anthropogenic methane source of 40.2-42.7 Tg a-1, as compared to 24.9-27.0 Tg a-1 in the EDGAR and EPA bottom-up inventories, and 30.0-44.5 Tg a-1 in recent inverse studies. Our estimate is supported by independent surface and aircraft data and by previous inverse studies for California. We find that the emissions are highest in the southern-central US, the Central Valley of California, and Florida wetlands; large isolated point sources such as the US Four Corners also contribute. Using prior information on source locations, we attribute 29-44 % of US anthropogenic methane emissions to livestock, 22-31 % to oil/gas, 20 % to landfills/wastewater, and 11-15 % to coal. Wetlands contribute an additional 9.0-10.1 Tg a-1.

  19. High-resolution forest canopy height estimation in an African blue carbon ecosystem.

    PubMed

    Lagomasino, David; Fatoyinbo, Temilola; Lee, Seung-Kuk; Simard, Marc

    2015-10-01

    Mangrove forests are one of the most productive and carbon dense ecosystems that are only found at tidally inundated coastal areas. Forest canopy height is an important measure for modeling carbon and biomass dynamics, as well as land cover change. By taking advantage of the flat terrain and dense canopy cover, the present study derived digital surface models (DSMs) using stereo-photogrammetric techniques on high-resolution spaceborne imagery (HRSI) for southern Mozambique. A mean-weighted ground surface elevation factor was subtracted from the HRSI DSM to accurately estimate the canopy height in mangrove forests in southern Mozambique. The mean and H100 tree height measured in both the field and with the digital canopy model provided the most accurate results with a vertical error of 1.18-1.84 m, respectively. Distinct patterns were identified in the HRSI canopy height map that could not be discerned from coarse shuttle radar topography mission canopy maps even though the mode and distribution of canopy heights were similar over the same area. Through further investigation, HRSI DSMs have the potential of providing a new type of three-dimensional dataset that could serve as calibration/validation data for other DSMs generated from spaceborne datasets with much larger global coverage. HSRI DSMs could be used in lieu of Lidar acquisitions for canopy height and forest biomass estimation, and be combined with passive optical data to improve land cover classifications.

  20. High-Resolution Forest Canopy Height Estimation in an African Blue Carbon Ecosystem

    NASA Technical Reports Server (NTRS)

    Lagomasino, David; Fatoyinbo, Temilola; Lee, Seung-Kuk; Simard, Marc

    2015-01-01

    Mangrove forests are one of the most productive and carbon dense ecosystems that are only found at tidally inundated coastal areas. Forest canopy height is an important measure for modeling carbon and biomass dynamics, as well as land cover change. By taking advantage of the flat terrain and dense canopy cover, the present study derived digital surface models (DSMs) using stereophotogrammetric techniques on high-resolution spaceborne imagery (HRSI) for southern Mozambique. A mean-weighted ground surface elevation factor was subtracted from the HRSI DSM to accurately estimate the canopy height in mangrove forests in southern Mozambique. The mean and H100 tree height measured in both the field and with the digital canopy model provided the most accurate results with a vertical error of 1.18-1.84 m, respectively. Distinct patterns were identified in the HRSI canopy height map that could not be discerned from coarse shuttle radar topography mission canopy maps even though the mode and distribution of canopy heights were similar over the same area. Through further investigation, HRSI DSMs have the potential of providing a new type of three-dimensional dataset that could serve as calibration/validation data for other DSMs generated from spaceborne datasets with much larger global coverage. HSRI DSMs could be used in lieu of Lidar acquisitions for canopy height and forest biomass estimation, and be combined with passive optical data to improve land cover classifications.

  1. Estimation of Venus wind velocities from high-resolution infrared spectra. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Smith, M. A. H.

    1978-01-01

    Zonal velocity profiles in the Venus atmosphere above the clouds were estimated from measured asymmetries of HCl and HF infrared absorption lines in high-resolution Fourier interferometer spectra of the planet. These asymmetries are caused by both pressure-induced shifts in the positions of the hydrogen-halide lines perturbed by CO2 and Doppler shifts due to atmospheric motions. Particularly in the case of the HCl 2-0 band, the effects of the two types of line shifts can be easily isolated, making it possible to estimate a profile of average Venus equatorial zonal velocity as a function of pressure in the region roughly 60 to 70 km above the surface of the planet. The mean profiles obtained show strong vertical shear in the Venus zonal winds near the cloud-top level, and both the magnitude and direction of winds at all levels in this region appear to vary greatly with longitude relative to the sub-solar point.

  2. Improving Accuracy and Temporal Resolution of Learning Curve Estimation for within- and across-Session Analysis

    PubMed Central

    Tabelow, Karsten; König, Reinhard; Polzehl, Jörg

    2016-01-01

    Estimation of learning curves is ubiquitously based on proportions of correct responses within moving trial windows. Thereby, it is tacitly assumed that learning performance is constant within the moving windows, which, however, is often not the case. In the present study we demonstrate that violations of this assumption lead to systematic errors in the analysis of learning curves, and we explored the dependency of these errors on window size, different statistical models, and learning phase. To reduce these errors in the analysis of single-subject data as well as on the population level, we propose adequate statistical methods for the estimation of learning curves and the construction of confidence intervals, trial by trial. Applied to data from an avoidance learning experiment with rodents, these methods revealed performance changes occurring at multiple time scales within and across training sessions which were otherwise obscured in the conventional analysis. Our work shows that the proper assessment of the behavioral dynamics of learning at high temporal resolution can shed new light on specific learning processes, and, thus, allows to refine existing learning concepts. It further disambiguates the interpretation of neurophysiological signal changes recorded during training in relation to learning. PMID:27303809

  3. Air-sea exchange over Black Sea estimated from high resolution regional climate simulations

    NASA Astrophysics Data System (ADS)

    Velea, Liliana; Bojariu, Roxana; Cica, Roxana

    2013-04-01

    Black Sea is an important influencing factor for the climate of bordering countries, showing cyclogenetic activity (Trigo et al, 1999) and influencing Mediterranean cyclones passing over. As for other seas, standard observations of the atmosphere are limited in time and space and available observation-based estimations of air-sea exchange terms present quite large ranges of uncertainty. The reanalysis datasets (e.g. ERA produced by ECMWF) provide promising validation estimates of climatic characteristics against the ones in available climatic data (Schrum et al, 2001), while cannot reproduce some local features due to relatively coarse horizontal resolution. Detailed and realistic information on smaller-scale processes are foreseen to be provided by regional climate models, due to continuous improvements of physical parameterizations and numerical solutions and thus affording simulations at high spatial resolution. The aim of the study is to assess the potential of three regional climate models in reproducing known climatological characteristics of air-sea exchange over Black Sea, as well as to explore the added value of the model compared to the input (reanalysis) data. We employ results of long-term (1961-2000) simulations performed within ENSEMBLE project (http://ensemblesrt3.dmi.dk/) using models ETHZ-CLM, CNRM-ALADIN, METO-HadCM, for which the integration domain covers the whole area of interest. The analysis is performed for the entire basin for several variables entering the heat and water budget terms and available as direct output from the models, at seasonal and annual scale. A comparison with independent data (ERA-INTERIM) and findings from other studies (e.g. Schrum et al, 2001) is also presented. References: Schrum, C., Staneva, J., Stanev, E. and Ozsoy, E., 2001: Air-sea exchange in the Black Sea estimated from atmospheric analysis for the period 1979-1993, J. Marine Systems, 31, 3-19 Trigo, I. F., T. D. Davies, and G. R. Bigg (1999): Objective

  4. Effects of measurement resolution on the analysis of temperature time series for stream-aquifer flux estimation

    NASA Astrophysics Data System (ADS)

    Soto-López, Carlos D.; Meixner, Thomas; Ferré, Ty P. A.

    2011-12-01

    From its inception in the mid-1960s, the use of temperature time series (thermographs) to estimate vertical fluxes has found increasing use in the hydrologic community. Beginning in 2000, researchers have examined the impacts of measurement and parameter uncertainty on the estimates of vertical fluxes. To date, the effects of temperature measurement discretization (resolution), a characteristic of all digital temperature loggers, on the determination of vertical fluxes has not been considered. In this technical note we expand the analysis of recently published work to include the effects of temperature measurement resolution on estimates of vertical fluxes using temperature amplitude and phase shift information. We show that errors in thermal front velocity estimation introduced by discretizing thermographs differ when amplitude or phase shift data are used to estimate vertical fluxes. We also show that under similar circumstances sensor resolution limits the range over which vertical velocities are accurately reproduced more than uncertainty in temperature measurements, uncertainty in sensor separation distance, and uncertainty in the thermal diffusivity combined. These effects represent the baseline error present and thus the best-case scenario when discrete temperature measurements are used to infer vertical fluxes. The errors associated with measurement resolution can be minimized by using the highest-resolution sensors available. But thoughtful experimental design could allow users to select the most cost-effective temperature sensors to fit their measurement needs.

  5. Estimation of crops biomass and evapotranspiration from high spatial and temporal resolutions remote sensing data

    NASA Astrophysics Data System (ADS)

    Claverie, Martin; Demarez, Valérie; Duchemin, Benoît.; Ceschia, Eric; Hagolle, Olivier; Ducrot, Danielle; Keravec, Pascal; Beziat, Pierre; Dedieu, Pierre

    2010-05-01

    Carbon and water cycles are closely related to agricultural activities. Agriculture has been indeed identified by IPCC 2007 report as one of the options to sequester carbon in soil. Concerning the water resources, their consumptions by irrigated crops are called into question in view of demographic pressure. In the prospect of an assessment of carbon production and water consumption, the use of crop models at a regional scale is a challenging issue. The recent availability of high spatial resolution (10 m) optical sensors associated to high temporal resolution (1 day) such as FORMOSAT-2 and, in the future, Venµs and SENTINEL-2 will offer new perspectives for agricultural monitoring. In this context, the objective of this work is to show how multi-temporal satellite observations acquired at high spatial resolution are useful for a regional monitoring of following crops biophysical variables: leaf area index (LAI), aboveground biomass (AGB) and evapotranspiration (ET). This study focuses on three summer crops dominant in South-West of France: maize, sunflower and soybean. A unique images data set (82 FORMOSAT-2 images over four consecutive years, 2006-2009) was acquired for this project. The experimental data set includes LAI and AGB measurements over eight agricultural fields. Two fields were intensively monitored where ET flux were measured with a 30 minutes time step using eddy correlation methods. The modelisation approach is based on FAO-56 method coupled with a vegetation functioning model based on Monteith theory: the SAFY model [5]. The model operates at a daily time step model to provide estimates of plant characteristics (LAI, AGB), soil conditions (soil water content) and water use (ET). As a key linking variable, LAI is deduced from FORMOSAT-2 reflectances images, and then introduced into the SAFY model to provide spatial and temporal estimates of these biophysical variables. Most of the SAFY parameters are crop related and have been fixed according to

  6. The Fundamental Structure of UV-Irradiated Cloud Edges: Combined ALMA and IRAM-30m Observations of the Orion Bar

    NASA Astrophysics Data System (ADS)

    Goicoechea, J.; Cuadrado, S.; Pety, J.; Ag'undez, M.; Cernicharo, J.; Chapillon, E.; Dumas, G.; Fuente, A.; Gerin, M.; Joblin, C.; Marcelino, N.; Müller, H. S. P.; Pilleri, P.

    2015-12-01

    The Orion Bar is the prototypical photodissociation region (PDR) exposed to a far-UV radiation field (FUV) of a few 104 times the mean interstellar field. Because of its proximity and nearly edge-on orientation, it provides a unique laboratory to study the physical and chemical gradients of a strongly FUV-illuminated molecular cloud. Using ALMA at ˜350 GHz, we have observed a field-of-view of ˜40”×40” toward the Orion Bar PDR consisting of a mosaic of 27 Nyquist-sampled pointings. These observations provide an unprecedented high angular resolution view (˜1” or ˜414 AU at the distance to Orion) of the most exposed molecular cloud edge. In addition, ACA and IRAM-30m maps were used to produce the short-spacing visibilities filtered out by the ALMA array. These interferometric observations complement a complete line survey we have carried out using the IRAM-30m telescope between ˜80 GHz and ˜360 GHz. Despite being a harsh environment, over 60 species with up to 6 atoms have been identified, including main isotopologues (D, 13C, 18O, 17O, 34S, 33S, and 15N). The first molecular line images of the Orion Bar obtained with ALMA at ˜1” resolution reveal the fundamental structure in density and temperature of the molecular gas as well as its complex kinematics at an unprecedented spatial resolution. This early data set also allowed us to compute corrected line frequencies for SH+, an interesting hydride tracing reactions of S+ with vibrationally excited H2 in the PDR edge.

  7. High-Resolution Spatial Distribution and Estimation of Access to Improved Sanitation in Kenya

    PubMed Central

    Jia, Peng; Anderson, John D.; Leitner, Michael; Rheingans, Richard

    2016-01-01

    Background Access to sanitation facilities is imperative in reducing the risk of multiple adverse health outcomes. A distinct disparity in sanitation exists among different wealth levels in many low-income countries, which may hinder the progress across each of the Millennium Development Goals. Methods The surveyed households in 397 clusters from 2008–2009 Kenya Demographic and Health Surveys were divided into five wealth quintiles based on their national asset scores. A series of spatial analysis methods including excess risk, local spatial autocorrelation, and spatial interpolation were applied to observe disparities in coverage of improved sanitation among different wealth categories. The total number of the population with improved sanitation was estimated by interpolating, time-adjusting, and multiplying the surveyed coverage rates by high-resolution population grids. A comparison was then made with the annual estimates from United Nations Population Division and World Health Organization /United Nations Children's Fund Joint Monitoring Program for Water Supply and Sanitation. Results The Empirical Bayesian Kriging interpolation produced minimal root mean squared error for all clusters and five quintiles while predicting the raw and spatial coverage rates of improved sanitation. The coverage in southern regions was generally higher than in the north and east, and the coverage in the south decreased from Nairobi in all directions, while Nyanza and North Eastern Province had relatively poor coverage. The general clustering trend of high and low sanitation improvement among surveyed clusters was confirmed after spatial smoothing. Conclusions There exists an apparent disparity in sanitation among different wealth categories across Kenya and spatially smoothed coverage rates resulted in a closer estimation of the available statistics than raw coverage rates. Future intervention activities need to be tailored for both different wealth categories and nationally

  8. Estimating forest canopy attributes via airborne, high-resolution, multispectral imagery in midwest forest types

    NASA Astrophysics Data System (ADS)

    Gatziolis, Demetrios

    An investigation of the utility of high spatial resolution (sub-meter), 16-bit, multispectral, airborne digital imagery for forest land cover mapping in the heterogeneous and structurally complex forested landscapes of northern Michigan is presented. Imagery frame registration and georeferencing issues are presented and a novel approach for bi-directional reflectance distribution function (BRDF) effects correction and between-frame brightness normalization is introduced. Maximum likelihood classification of five cover type classes is performed over various geographic aggregates of 34 plots established in the study area that were designed according to the Forest Inventory and Analysis protocol. Classification accuracy estimates show that although band registration and BRDF corrections and brightness normalization provide an approximately 5% improvement over the raw imagery data, overall classification accuracy remains relatively low, barely exceeding 50%. Computed kappa coefficients reveal no statistical differences among classification trials. Classification results appear to be independent of geographic aggregations of sampling plots. Estimation of forest stand canopy parameter parameters (stem density, canopy closure, and mean crown diameter) is based on quantifying the spatial autocorrelation among pixel digital numbers (DN) using variogram analysis and slope break analysis, an alternative non-parametric approach. Parameter estimation and cover type classification proceed from the identification of tree apexes. Parameter accuracy assessment is evaluated via value comparison with a spatially precise set of field observations. In general, slope-break-based parameter estimates are superior to those obtained using variograms. Estimated root mean square errors at the plot level for the former average 6.5% for stem density, 3.5% for canopy closure and 2.5% for mean crown diameter, which are less than or equal to error rates obtained via traditional forest stand

  9. a Class of Regression-Cum Estimators in Two-Phase Sampling for Utilizing Information from High Resolution Satellite Data

    NASA Astrophysics Data System (ADS)

    Handique, B. K.

    2012-07-01

    Two-phase sampling design offers a variety of possibilities for effective use of auxiliary information such as those from high resolution remote sensing data. Continuous satellite data with large area coverage provide scope for deriving population values of the auxiliary variables, which can effectively be used for estimating the population parameters of the variable of interest. This study has been made to examine the possibilities of different forms of auxiliary information derived from remote sensing data in two-phase sampling design and suggest an appropriate estimator that will be of broad interest and applications. A new class of regression-cum-ratio estimators has been proposed for two-phase sampling using information on two auxiliary variables derived from high resolution satellite data. The bias and the mean square error (MSE) of the proposed estimators have been obtained up to first order approximation. Efficiency comparison of the proposed estimators has been made with some traditional estimators. The proposed estimator is found to be more efficient than the usual regression and ratio estimators. Numerical illustration has been carried out to examine the efficiency of the estimator in case of forest timber volume estimation utilizing tree crown diameter and tree height as auxiliary variables. It is shown that these estimators can be employed in a variety of conditions where there is strong correlation of satellite derived information with sample based ground measurements and when the cost of ground measurements is relatively high.

  10. VizieR Online Data Catalog: IRAM 30m CO-observations in W43 (Carlhoff+, 2013)

    NASA Astrophysics Data System (ADS)

    Carlhoff, P.; Nguyen Luong, Q.; Schilke, P.; Motte, F.; Schneider, N.; Beuther, H.; Bontemps, S.; Heitsch, F.; Hill, T.; Kramer, C.; Ossenkopf, V.; Schuller, F.; Simon, R.; Wyrowski, F.

    2013-10-01

    We observed molecular clouds in the giant star forming region W43. For this project we used the IRAM 30m telescope to observe the molecular emission lines 13CO (2-1) and C18O (2-1), that trace the mid-density (n~103cm-3) molecular gas. The lines were observed with the HERA receiver and the VESPA backend. At the observed frequencies the IRAM 30m has a beam size of 11.7". We include two FITS files containing the data-cubes (pos-pos-vel) of the 13CO and C18O emission lines of the W43 complex. We used equatorial coordinates for the spatial dimensions and vlsr for the spectral dimension. The pixel size is 5.9" in spatial dimension and the spectral resolution is 0.16km/s. All values are in K. The data-cubes span an area of about 1x1.5° (RAxDec) around the center of the maps at 18:46:54.4 -02:14:11 (EQ=J2000) and the velocity range from 30 to 130km/s and include the complete W43 complex and several fore- and background clouds. (2 data files).

  11. Estimating global and North American methane emissions with high spatial resolution using GOSAT satellite data

    NASA Astrophysics Data System (ADS)

    Turner, A. J.; Jacob, D. J.; Wecht, K. J.; Maasakkers, J. D.; Biraud, S. C.; Boesch, H.; Bowman, K. W.; Deutscher, N. M.; Dubey, M. K.; Griffith, D. W. T.; Hase, F.; Kuze, A.; Notholt, J.; Ohyama, H.; Parker, R.; Payne, V. H.; Sussmann, R.; Velazco, V. A.; Warneke, T.; Wennberg, P. O.; Wunch, D.

    2015-02-01

    We use 2009-2011 space-borne methane observations from the Greenhouse Gases Observing SATellite (GOSAT) to constrain global and North American inversions of methane emissions with 4° × 5° and up to 50 km × 50 km spatial resolution, respectively. The GOSAT data are first evaluated with atmospheric methane observations from surface networks (NOAA, TCCON) and aircraft (NOAA/DOE, HIPPO), using the GEOS-Chem chemical transport model as a platform to facilitate comparison of GOSAT with in situ data. This identifies a high-latitude bias between the GOSAT data and GEOS-Chem that we correct via quadratic regression. The surface and aircraft data are subsequently used for independent evaluation of the methane source inversions. Our global adjoint-based inversion yields a total methane source of 539 Tg a-1 and points to a large East Asian overestimate in the EDGARv4.2 inventory used as a prior. Results serve as dynamic boundary conditions for an analytical inversion of North American methane emissions using radial basis functions to achieve high resolution of large sources and provide full error characterization. We infer a US anthropogenic methane source of 40.2-42.7 Tg a-1, as compared to 24.9-27.0 Tg a-1 in the EDGAR and EPA bottom-up inventories, and 30.0-44.5 Tg a-1 in recent inverse studies. Our estimate is supported by independent surface and aircraft data and by previous inverse studies for California. We find that the emissions are highest in the South-Central US, the Central Valley of California, and Florida wetlands, large isolated point sources such as the US Four Corners also contribute. We attribute 29-44% of US anthropogenic methane emissions to livestock, 22-31% to oil/gas, 20% to landfills/waste water, and 11-15% to coal with an additional 9.0-10.1 Tg a-1 source from wetlands.

  12. GLONASS fractional-cycle bias estimation across inhomogeneous receivers for PPP ambiguity resolution

    NASA Astrophysics Data System (ADS)

    Geng, Jianghui; Bock, Yehuda

    2016-04-01

    The key issue to enable precise point positioning with ambiguity resolution (PPP-AR) is to estimate fractional-cycle biases (FCBs), which mainly relate to receiver and satellite hardware biases, over a network of reference stations. While this has been well achieved for GPS, FCB estimation for GLONASS is difficult because (1) satellites do not share the same frequencies as a result of Frequency Division Multiple Access (FDMA) signals; (2) and even worse, pseudorange hardware biases of receivers vary in an irregular manner with manufacturers, antennas, domes, firmware, etc., which especially complicates GLONASS PPP-AR over inhomogeneous receivers. We propose a general approach where external ionosphere products are introduced into GLONASS PPP to estimate precise FCBs that are less impaired by pseudorange hardware biases of diverse receivers to enable PPP-AR. One month of GLONASS data at about 550 European stations were processed. From an exemplary network of 51 inhomogeneous receivers, including four receiver types with various antennas and spanning about 800 km in both longitudinal and latitudinal directions, we found that 92.4 % of all fractional parts of GLONASS wide-lane ambiguities agree well within ± 0.15 cycles with a standard deviation of 0.09 cycles if global ionosphere maps (GIMs) are introduced, compared to only 51.7 % within ± 0.15 cycles and a larger standard deviation of 0.22 cycles otherwise. Hourly static GLONASS PPP-AR at 40 test stations can reach position estimates of about 1 and 2 cm in RMS from ground truth for the horizontal and vertical components, respectively, which is comparable to hourly GPS PPP-AR. Integrated GLONASS and GPS PPP-AR can further achieve an RMS of about 0.5 cm in horizontal and 1-2 cm in vertical components. We stress that the performance of GLONASS PPP-AR across inhomogeneous receivers depends on the accuracy of ionosphere products. GIMs have a modest accuracy of only 2-8 TECU (Total Electron Content Unit) in vertical

  13. Estimating the model resolution matrix for large seismic tomography problems based on Lanczos bidiagonalization with partial reorthogonalization

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Thurber, C. H.

    2007-07-01

    The PROPACK package developed by Larsen is able to efficiently and accurately estimate singular values and vectors for large matrices based on the Lanczos bidiagonalization with partial reorthogonalization. We incorporate the Pavtial Reorthogonalization Package (PROPACK) package into the double-difference seismic tomography code tomoDD and estimate the model resolution matrix for large seismic tomography problems. Compared to previous Least Squares QR (LSQR)-based methods for estimating the model resolution matrix the PROPACK-based method calculates the full resolution matrix and thus gives a complete description of how well the model is resolved. Several observations are drawn from the application to data from the 2001 eruption of Mt Etna: for this example, it is reasonable to use ray-sampling density information to characterize the model resolution qualitatively; the model resolution resulting from just velocity inversion bears a close linear relationship to that from simultaneous inversion but always overestimates resolution; and the inversion system using differential times has a greater ability to resolve the source region structure than the system using absolute times.

  14. Estimation of Coastal Freshwater Discharge into Prince William Sound using a High-Resolution Hydrological Model

    NASA Astrophysics Data System (ADS)

    Beamer, J. P.; Hill, D. F.; Liston, G. E.; Arendt, A. A.; Hood, E. W.

    2013-12-01

    In Prince William Sound (PWS), Alaska, there is a pressing need for accurate estimates of the spatial and temporal variations in coastal freshwater discharge (FWD). FWD into PWS originates from streamflow due to rainfall, annual snowmelt, and changes in stored glacier mass and is important because it helps establish spatial and temporal patterns in ocean salinity and temperature, and is a time-varying boundary condition for oceanographic circulation models. Previous efforts to model FWD into PWS have been heavily empirical, with many physical processes absorbed into calibration coefficients that, in many cases, were calibrated to streams and rivers not hydrologically similar to those discharging into PWS. In this work we adapted and validated a suite of high-resolution (in space and time), physically-based, distributed weather, snowmelt, and runoff-routing models designed specifically for snow melt- and glacier melt-dominated watersheds like PWS in order to: 1) provide high-resolution, real-time simulations of snowpack and FWD, and 2) provide a record of historical variations of FWD. SnowModel, driven with gridded topography, land cover, and 32 years (1979-2011) of 3-hourly North American Regional Reanalysis (NARR) atmospheric forcing data, was used to simulate snowpack accumulation and melt across a PWS model domain. SnowModel outputs of daily snow water equivalent (SWE) depth and grid-cell runoff volumes were then coupled with HydroFlow, a runoff-routing model which routed snowmelt, glacier-melt, and rainfall to each watershed outlet (PWS coastline) in the simulation domain. The end product was a continuous 32-year simulation of daily FWD into PWS. In order to validate the models, SWE and snow depths from SnowModel were compared with observed SWE and snow depths from SnoTel and snow survey data, and discharge from HydroFlow was compared with observed streamflow measurements. As a second phase of this research effort, the coupled models will be set-up to run in

  15. High Resolution/High Fidelity Seismic Imaging and Parameter Estimation for Geological Structure and Material Characterization

    SciTech Connect

    Ru-Shan Wu; Xiao-Bi Xie

    2008-06-08

    Our proposed work on high resolution/high fidelity seismic imaging focused on three general areas: (1) development of new, more efficient, wave-equation-based propagators and imaging conditions, (2) developments towards amplitude-preserving imaging in the local angle domain, in particular, imaging methods that allow us to estimate the reflection as a function of angle at a layer boundary, and (3) studies of wave inversion for local parameter estimation. In this report we summarize the results and progress we made during the project period. The report is divided into three parts, totaling 10 chapters. The first part is on resolution analysis and its relation to directional illumination analysis. The second part, which is composed of 6 chapters, is on the main theme of our work, the true-reflection imaging. True-reflection imaging is an advanced imaging technology which aims at keeping the image amplitude proportional to the reflection strength of the local reflectors or to obtain the reflection coefficient as function of reflection-angle. There are many factors which may influence the image amplitude, such as geometrical spreading, transmission loss, path absorption, acquisition aperture effect, etc. However, we can group these into two categories: one is the propagator effect (geometric spreading, path losses); the other is the acquisition-aperture effect. We have made significant progress in both categories. We studied the effects of different terms in the true-amplitude one-way propagators, especially the terms including lateral velocity variation of the medium. We also demonstrate the improvements by optimizing the expansion coefficients in different terms. Our research also includes directional illumination analysis for both the one-way propagators and full-wave propagators. We developed the fast acquisition-aperture correction method in the local angle-domain, which is an important element in the true-reflection imaging. Other developments include the super

  16. Estimating global and North American methane emissions with high spatial resolution using GOSAT satellite data

    DOE PAGES

    Turner, A. J.; Jacob, D. J.; Wecht, K. J.; ...

    2015-06-30

    We use 2009–2011 space-borne methane observations from the Greenhouse Gases Observing SATellite (GOSAT) to estimate global and North American methane emissions with 4° × 5° and up to 50 km × 50 km spatial resolution, respectively. GEOS-Chem and GOSAT data are first evaluated with atmospheric methane observations from surface and tower networks (NOAA/ESRL, TCCON) and aircraft (NOAA/ESRL, HIPPO), using the GEOS-Chem chemical transport model as a platform to facilitate comparison of GOSAT with in situ data. This identifies a high-latitude bias between the GOSAT data and GEOS-Chem that we correct via quadratic regression. Our global adjoint-based inversion yields a totalmore » methane source of 539 Tg a−1 with some important regional corrections to the EDGARv4.2 inventory used as a prior. Results serve as dynamic boundary conditions for an analytical inversion of North American methane emissions using radial basis functions to achieve high resolution of large sources and provide error characterization. We infer a US anthropogenic methane source of 40.2–42.7 Tg a−1, as compared to 24.9–27.0 Tg a−1 in the EDGAR and EPA bottom-up inventories, and 30.0–44.5 Tg a−1 in recent inverse studies. Our estimate is supported by independent surface and aircraft data and by previous inverse studies for California. We find that the emissions are highest in the southern–central US, the Central Valley of California, and Florida wetlands; large isolated point sources such as the US Four Corners also contribute. Using prior information on source locations, we attribute 29–44 % of US anthropogenic methane emissions to livestock, 22–31 % to oil/gas, 20 % to landfills/wastewater, and 11–15 % to coal. Wetlands contribute an additional 9.0–10.1 Tg a−1.« less

  17. High-resolution estimates of Southwest Indian Ridge plate motions, 20 Ma to present

    NASA Astrophysics Data System (ADS)

    DeMets, C.; Merkouriev, S.; Sauter, D.

    2015-12-01

    We present the first estimates of Southwest Indian Ridge (SWIR) plate motions at high temporal resolution during the Quaternary and Neogene based on nearly 5000 crossings of 21 magnetic reversals out to C6no (19.72 Ma) and the digitized traces of 17 fracture zones and transform faults. Our reconstructions of this slow-spreading mid-ocean ridge reveal several unexpected results with notable implications for regional and global plate reconstructions since 20 Ma. Extrapolations of seafloor opening distances to zero-age seafloor based on reconstructions of reversals C1n (0.78 Ma) through C3n.4 (5.2 Ma) reveal evidence for surprisingly large outward displacement of 5 ± 1 km west of 32°E, where motion between the Nubia and Antarctic plates occurs, but 2 ± 1 km east of 32°E, more typical of most mid-ocean ridges. Newly estimated SWIR seafloor spreading rates are up to 15 per cent slower everywhere along the ridge than previous estimates. Reconstructions of the numerous observations for times back to 11 Ma confirm the existence of the hypothesized Lwandle plate at high confidence level and indicate that the Lwandle plate's western and eastern boundaries respectively intersect the ridge near the Andrew Bain transform fault complex at 32°E and between ˜45°E and 52°E, in accord with previous results. The Nubia-Antarctic, Lwandle-Antarctic and Somalia-Antarctic rotation sequences that best fit many magnetic reversal, fracture zone and transform fault crossings define previously unknown changes in the Neogene motions of all three plate pairs, consisting of ˜20 per cent slowdowns in their spreading rates at 7.2^{+0.9 }_{ -1.4} Ma if we enforce a simultaneous change in motion everywhere along the SWIR and gradual 3°-7° anticlockwise rotations of the relative slip directions. We apply trans-dimensional Bayesian analysis to our noisy, best-fitting rotation sequences in order to estimate less-noisy rotation sequences suitable for use in future global plate reconstructions

  18. Estimation of red-light running frequency using high-resolution traffic and signal data.

    PubMed

    Chen, Peng; Yu, Guizhen; Wu, Xinkai; Ren, Yilong; Li, Yueguang

    2017-03-23

    Red-light-running (RLR) emerges as a major cause that may lead to intersection-related crashes and endanger intersection safety. To reduce RLR violations, it's critical to identify the influential factors associated with RLR and estimate RLR frequency. Without resorting to video camera recordings, this study investigates this important issue by utilizing high-resolution traffic and signal event data collected from loop detectors at five intersections on Trunk Highway 55, Minneapolis, MN. First, a simple method is proposed to identify RLR by fully utilizing the information obtained from stop bar detectors, downstream entrance detectors and advance detectors. Using 12 months of event data, a total of 6550 RLR cases were identified. According to a definition of RLR frequency as the conditional probability of RLR on a certain traffic or signal condition (veh/1000veh), the relationships between RLR frequency and some influential factors including arriving time at advance detector, approaching speed, headway, gap to the preceding vehicle on adjacent lane, cycle length, geometric characteristics and even snowing weather were empirically investigated. Statistical analysis shows good agreement with the traffic engineering practice, e.g., RLR is most likely to occur on weekdays during peak periods under large traffic demands and longer signal cycles, and a total of 95.24% RLR events occurred within the first 1.5s after the onset of red phase. The findings confirmed that vehicles tend to run the red light when they are close to intersection during phase transition, and the vehicles following the leading vehicle with short headways also likely run the red light. Last, a simplified nonlinear regression model is proposed to estimate RLR frequency based on the data from advance detector. The study is expected to helpbetter understand RLR occurrence and further contribute to the future improvement of intersection safety.

  19. NIKA2, a dual-band millimetre camera on the IRAM 30 m telescope to map the cold universe

    NASA Astrophysics Data System (ADS)

    Désert, F.-X.; Adam, R.; Ade, P.; André, P.; Aussel, H.; Beelen, A.; Benoît, A.; Bideaud, A.; Billot, N.; Bourrion, O.; Calvo, M.; Catalano, A.; Coiffard, G.; Comis, B.; Doyle, S.; Goupy, J.; Kramer, C.; Lagache, G.; Leclercq, S.; Lestrade, J.-F.; Macías-Pérez, J. F.; Maury, A.; Mauskopf, P.; Mayet, F.; Monfardini, A.; Pajot, F.; Pascale, E.; Perotto, L.; Pisano, G.; Ponthieu, N.; Revéret, V.; Ritacco, A.; Rodriguez, L.; Romero, C.; Roussel, H.; Ruppin, F.; Soler, J.; Schuster, K.; Sievers, A.; Triqueneaux, S.; Tucker, C.; Zylka, R.

    2016-12-01

    A consortium led by Institut Néel (Grenoble) has just finished installing a new powerful millimetre camera NIKA2 on the IRAM 30 m telescope. It has an instantaneous field-of-view of 6.5 arcminutes at both 1.2 and 2.0 mm with polarimetric capabilities at 1.2 mm. NIKA2 provides a near diffraction-limited angular resolution (resp. 12 and 18 arcseconds). The 3 detector arrays are made of more than 1000 KIDs each. KIDs are new superconducting devices emerging as an alternative to bolometers. The commissionning is ongoing in 2016 with a likely opening to the IRAM community in early 2017. NIKA2 is a very promising multi-purpose instrument which will enable many scientific discoveries in the coming decade.

  20. Estimation of integral curves from high angular resolution diffusion imaging (HARDI) data

    PubMed Central

    Carmichael, Owen; Sakhanenko, Lyudmila

    2015-01-01

    We develop statistical methodology for a popular brain imaging technique HARDI based on the high order tensor model by Özarslan and Mareci [10]. We investigate how uncertainty in the imaging procedure propagates through all levels of the model: signals, tensor fields, vector fields, and fibers. We construct asymptotically normal estimators of the integral curves or fibers which allow us to trace the fibers together with confidence ellipsoids. The procedure is computationally intense as it blends linear algebra concepts from high order tensors with asymptotical statistical analysis. The theoretical results are illustrated on simulated and real datasets. This work generalizes the statistical methodology proposed for low angular resolution diffusion tensor imaging by Carmichael and Sakhanenko [3], to several fibers per voxel. It is also a pioneering statistical work on tractography from HARDI data. It avoids all the typical limitations of the deterministic tractography methods and it delivers the same information as probabilistic tractography methods. Our method is computationally cheap and it provides well-founded mathematical and statistical framework where diverse functionals on fibers, directions and tensors can be studied in a systematic and rigorous way. PMID:25937674

  1. Estimation of integral curves from high angular resolution diffusion imaging (HARDI) data.

    PubMed

    Carmichael, Owen; Sakhanenko, Lyudmila

    2015-05-15

    We develop statistical methodology for a popular brain imaging technique HARDI based on the high order tensor model by Özarslan and Mareci [10]. We investigate how uncertainty in the imaging procedure propagates through all levels of the model: signals, tensor fields, vector fields, and fibers. We construct asymptotically normal estimators of the integral curves or fibers which allow us to trace the fibers together with confidence ellipsoids. The procedure is computationally intense as it blends linear algebra concepts from high order tensors with asymptotical statistical analysis. The theoretical results are illustrated on simulated and real datasets. This work generalizes the statistical methodology proposed for low angular resolution diffusion tensor imaging by Carmichael and Sakhanenko [3], to several fibers per voxel. It is also a pioneering statistical work on tractography from HARDI data. It avoids all the typical limitations of the deterministic tractography methods and it delivers the same information as probabilistic tractography methods. Our method is computationally cheap and it provides well-founded mathematical and statistical framework where diverse functionals on fibers, directions and tensors can be studied in a systematic and rigorous way.

  2. Global sensitivity of high-resolution estimates of crop water footprint

    NASA Astrophysics Data System (ADS)

    Tuninetti, Marta; Tamea, Stefania; D'Odorico, Paolo; Laio, Francesco; Ridolfi, Luca

    2015-10-01

    Most of the human appropriation of freshwater resources is for agriculture. Water availability is a major constraint to mankind's ability to produce food. The notion of virtual water content (VWC), also known as crop water footprint, provides an effective tool to investigate the linkage between food and water resources as a function of climate, soil, and agricultural practices. The spatial variability in the virtual water content of crops is here explored, disentangling its dependency on climate and crop yields and assessing the sensitivity of VWC estimates to parameter variability and uncertainty. Here we calculate the virtual water content of four staple crops (i.e., wheat, rice, maize, and soybean) for the entire world developing a high-resolution (5 × 5 arc min) model, and we evaluate the VWC sensitivity to input parameters. We find that food production almost entirely depends on green water (>90%), but, when applied, irrigation makes crop production more water efficient, thus requiring less water. The spatial variability of the VWC is mostly controlled by the spatial patterns of crop yields with an average correlation coefficient of 0.83. The results of the sensitivity analysis show that wheat is most sensitive to the length of the growing period, rice to reference evapotranspiration, maize and soybean to the crop planting date. The VWC sensitivity varies not only among crops, but also across the harvested areas of the world, even at the subnational scale.

  3. GISMO, an ELT in space: a giant (30-m) far-infrared and submillimeter space observatory

    NASA Astrophysics Data System (ADS)

    Hawarden, Timothy G.; Johnstone, Callum; Johnstone, Graeme

    2004-07-01

    We describe GISMO, a concept for a 30-m class achromatic diffractive Fesnel space telescope operating in the far-IR and submillimeter from ~20 μm to ~700 μm. The concept is based on the precepts of Hyde (1999). It involves two units, the Lens and Instrument spacecraft, 3 km apart in a halo orbit around the Earth-Sun L2 point. The primary lens, L1, is a 30.1-m, 32-zone f/100 Fresnel lens, fabricated from ultra-high molecular-weight polyethylene (UHMW-PE). It is 1.0 to 3.4 mm thick (the features are 2.4 mm high for a "design wavelength" of 1.2 mm) and made in 5 strips linked by fabric hinges. It is stowed for launch by folding and rolling. It is deployed warm, unrolled by pneumatic or mechanical means, unfolded by carbon-fiber struts with Shape Memory Alloy hinges and stiffened until cold by a peripheral inflatable ring. Re-oriented edgeways-on to the Sun behind a 5-layer sunshade, L1 will then cool by radiation to space, approaching ~10K after 200 - 300 days. The low equilibrium temperature occurs because the lens is very thin and has a huge view factor to space but a small one to the sunshade. The Instrument spacecraft resembles a smaller, colder (~4K) version of the James Webb Space Telescope and shares features of a concept for the SAFIR mission. A near-field Ritchey-Chretien telescope with a 3-segment off-axis 6m x 3m primary acts as field lens, re-imaging L1 on a 30-cm f/1 Fresnel Corrector lens of equal and opposite dispersion, producing an achromatic beam which is directed to a focal plane equipped with imaging and spectroscopic instruments. The "design wavelength" of the telescope is 1.2 mm and it is employed at its second and higher harmonics. The shortest wavelength, ~20μm, is set by the transmission properties of the lens material (illustrated here) and determines the design tolerances of the optical system. The overall mass is estimated at ~5 tonnes and the stowed length around 14 m. Technical challenges and areas of uncertainty for the design concept

  4. Estimating global and North American methane emissions with high spatial resolution using GOSAT satellite data

    DOE PAGES

    Turner, A. J.; Jacob, D. J.; Wecht, K. J.; ...

    2015-02-18

    We use 2009–2011 space-borne methane observations from the Greenhouse Gases Observing SATellite (GOSAT) to constrain global and North American inversions of methane emissions with 4° × 5° and up to 50 km × 50 km spatial resolution, respectively. The GOSAT data are first evaluated with atmospheric methane observations from surface networks (NOAA, TCCON) and aircraft (NOAA/DOE, HIPPO), using the GEOS-Chem chemical transport model as a platform to facilitate comparison of GOSAT with in situ data. This identifies a high-latitude bias between the GOSAT data and GEOS-Chem that we correct via quadratic regression. The surface and aircraft data are subsequently usedmore » for independent evaluation of the methane source inversions. Our global adjoint-based inversion yields a total methane source of 539 Tg a−1 and points to a large East Asian overestimate in the EDGARv4.2 inventory used as a prior. Results serve as dynamic boundary conditions for an analytical inversion of North American methane emissions using radial basis functions to achieve high resolution of large sources and provide full error characterization. We infer a US anthropogenic methane source of 40.2–42.7 Tg a−1, as compared to 24.9–27.0 Tg a−1 in the EDGAR and EPA bottom-up inventories, and 30.0–44.5 Tg a−1 in recent inverse studies. Our estimate is supported by independent surface and aircraft data and by previous inverse studies for California. We find that the emissions are highest in the South-Central US, the Central Valley of California, and Florida wetlands, large isolated point sources such as the US Four Corners also contribute. We attribute 29–44% of US anthropogenic methane emissions to livestock, 22–31% to oil/gas, 20% to landfills/waste water, and 11–15% to coal with an additional 9.0–10.1 Tg a−1 source from wetlands.« less

  5. A simulation study exploring the effects of sensor spatial resolution on estimates of cloud cover from satellites.

    NASA Technical Reports Server (NTRS)

    Shenk, W. E.; Salomonson, V. V.

    1972-01-01

    Investigation of the effects of sensor spatial resolution on estimating the amount of clouds covering the earth by simulating various cloud distributions and sizes, and measuring the known cloud amount with resolution of different sizes using a cloud-no cloud threshold technique often applied in automatic data processing. Cloud amount statistics have been tabulated for a three-orders-of-magnitude range in the ratio (R) of areal cloud size to areal resolution size for seven cloud amounts between 6 and 90%. Three different cloud patterns were used. These were 1) a regularly spaced pattern of homogeneous dots arranged in rows and columns (to simulate cloud streets), 2) a randomly spaced pattern of the same dots (to simulate randomly oriented cumulus clouds), and 3) a heterogeneous cloud size distribution irregularly spaced (to simulate a view of different cloud types and sizes). Two cloud amount estimation techniques were tested. Cloud amounts of 100% (method 1) and 50% (method 2) were assigned to partially filled resolution elements. Using criteria applicable to some studies carried out in the past, it is shown that cloud amount estimations can be in error by as much as 86 and 38%, respectively, for the two methods. Nomograms have been developed which subtantially improve the estimate of the true cloud cover for R less than 100, provided that R can be determined.

  6. On the calibration of Mars Orbiter Laser Altimeter surface roughness estimates using high-resolution DTMs

    NASA Astrophysics Data System (ADS)

    Poole, W.; Muller, J.-P.; Gupta, S.

    2012-04-01

    Planetary surface roughness is critical in the selection of suitable landing sites for robotic lander or roving missions. It has also been used in the identification of terrain, for better calibration of radar returns and improved understanding of aerodynamic roughness [1]. One of the secondary science goals of the Mars Orbiter Laser Altimeter (MOLA) was the study of surface roughness at 100 m, using the backscatter pulse width of the laser pulse, which has a footprint of 168 m in diameter [2]. The pulse width values in the final release (version L) of the MOLA Precision Experiment Data Record (PEDR) have been corrected for across track slopes and the removal of 'bad points', and footprint diameter was revised to 75 m, with a 35 m response length in [3]. We look here at comparing surface roughness values derived from the MOLA pulse-width data with surface roughness estimates derived at various scales from high-resolution digital terrain models (DTMs) to determine if these theoretically derived surface roughness lengths are physically meaningful. The final four potential landing sites for Mars Science Laboratory were used in this study, as they have extensive HiRISE (1m) and HRSC (50m) DTM coverage [4]. Pulse width data from both the MOLA PEDR (version L) and the data used in [3] was collected and compared for each of the sites against surface roughness estimates at various scales from HiRISE, and HRSC, DTMs using the RMS height. This assumed a circular footprint for each MOLA footprint and that the horizontal geolocation of the PEDR MOLA footprints was sufficiently accurate to only extract those DTM points which lay inside the footprints. Results from the MOLA PEDR data were extremely poor, and show no correlation with surface roughness measurements from DTMs. Results using the corrected data in [3] were mixed. Eberswalde and Holden Craters both show significantly improved correlations for a variety of surface roughness scales. The best correlations were found to

  7. The effect of flow data resolution on sediment yield estimation and channel design

    NASA Astrophysics Data System (ADS)

    Rosburg, Tyler T.; Nelson, Peter A.; Sholtes, Joel S.; Bledsoe, Brian P.

    2016-07-01

    The decision to use either daily-averaged or sub-daily streamflow records has the potential to impact the calculation of sediment transport metrics and stream channel design. Using bedload and suspended load sediment transport measurements collected at 138 sites across the United States, we calculated the effective discharge, sediment yield, and half-load discharge using sediment rating curves over long time periods (median record length = 24 years) with both daily-averaged and sub-daily streamflow records. A comparison of sediment transport metrics calculated with both daily-average and sub-daily stream flow data at each site showed that daily-averaged flow data do not adequately represent the magnitude of high stream flows at hydrologically flashy sites. Daily-average stream flow data cause an underestimation of sediment transport and sediment yield (including the half-load discharge) at flashy sites. The degree of underestimation was correlated with the level of flashiness and the exponent of the sediment rating curve. No consistent relationship between the use of either daily-average or sub-daily streamflow data and the resultant effective discharge was found. When used in channel design, computed sediment transport metrics may have errors due to flow data resolution, which can propagate into design slope calculations which, if implemented, could lead to unwanted aggradation or degradation in the design channel. This analysis illustrates the importance of using sub-daily flow data in the calculation of sediment yield in urbanizing or otherwise flashy watersheds. Furthermore, this analysis provides practical charts for estimating and correcting these types of underestimation errors commonly incurred in sediment yield calculations.

  8. Estimation of terrestrial carbon fluxes with 1km by 1km spatial-resolution using satellite- driven model

    NASA Astrophysics Data System (ADS)

    Sasai, T.; Nasahara, K.; Ito, A.; Saigusa, N.; Hirata, R.; Takagi, K.; Oikawa, T.

    2008-12-01

    Terrestrial carbon cycle is strongly affected by some local natural phenomena and human-induced activities, which bring change to the carbon exchanges via vegetation and soil microbe activities. In order to accurately understand a realistic spatial pattern in carbon exchanges including such an effect of local-scale events, we need to calculate carbon fluxes and storages with as detailed spatial resolution as possible. In response to this, we attempt to estimate terrestrial carbon fluxes with 1km by 1km spatial resolution using satellite-driven model. Study area of the model estimation is the Further East Asia region, which lies at 30-50 north latitude and 125-150 east longitude. The model is the Biosphere model integrating Eco-physiological And Mechanistic approaches using Satellite data (BEAMS) [Sasai et al., 2005, 2007]. Being aim at simulating terrestrial carbon exchanges under more realistic land surface condition, we applied as many as possible of satellite-observation products such as the standard MODIS, TRMM, and SRTM high-level land products as model inputs. In the model validation, we compared between model estimations and eddy covariance measurements at four flux sites. As a result, a correlation coefficient of the terrestrial carbon fluxes between estimations and measurements were high values, leading up that the model estimations are virtually reasonable. In model analysis, BEAMS was operated with 1km by 1km spatial resolution from 2001 to 2006. Spatial distributions in the annual mean NPP and NEP showed that high values were distributed over the hilly and plateau regions, and they were gradually decreasing towards the urban and high mountain areas, meaning that we could reflect an impact of the local-scale events in the carbon flux estimations. In future, we would extend study area to the East Asia region, and the carbon exchange map with 1km by 1km spatial- resolution is distributed on the website.

  9. High resolution land surface geophysical parameters estimation from ALOS PALSAR data

    Technology Transfer Automated Retrieval System (TEKTRAN)

    High resolution land surface geophysical products, such as soil moisture, surface roughness and vegetation water content, are essential for a variety of applications ranging from water management to regional climate predictions. In India high resolution geophysical products, in particular soil moist...

  10. Error Estimation in an Optimal Interpolation Scheme for High Spatial and Temporal Resolution SST Analyses

    NASA Technical Reports Server (NTRS)

    Rigney, Matt; Jedlovec, Gary; LaFontaine, Frank; Shafer, Jaclyn

    2010-01-01

    Heat and moisture exchange between ocean surface and atmosphere plays an integral role in short-term, regional NWP. Current SST products lack both spatial and temporal resolution to accurately capture small-scale features that affect heat and moisture flux. NASA satellite is used to produce high spatial and temporal resolution SST analysis using an OI technique.

  11. Three-dimensional estimates of tree canopies: Scaling from high-resolution UAV data to satellite observations

    NASA Astrophysics Data System (ADS)

    Sankey, T.; Donald, J.; McVay, J.

    2015-12-01

    High resolution remote sensing images and datasets are typically acquired at a large cost, which poses big a challenge for many scientists. Northern Arizona University recently acquired a custom-engineered, cutting-edge UAV and we can now generate our own images with the instrument. The UAV has a unique capability to carry a large payload including a hyperspectral sensor, which images the Earth surface in over 350 spectral bands at 5 cm resolution, and a lidar scanner, which images the land surface and vegetation in 3-dimensions. Both sensors represent the newest available technology with very high resolution, precision, and accuracy. Using the UAV sensors, we are monitoring the effects of regional forest restoration treatment efforts. Individual tree canopy width and height are measured in the field and via the UAV sensors. The high-resolution UAV images are then used to segment individual tree canopies and to derive 3-dimensional estimates. The UAV image-derived variables are then correlated to the field-based measurements and scaled to satellite-derived tree canopy measurements. The relationships between the field-based and UAV-derived estimates are then extrapolated to a larger area to scale the tree canopy dimensions and to estimate tree density within restored and control forest sites.

  12. Liver transplantation and anemia in familial amyloidosis ATTR V30M.

    PubMed

    Beirão, Idalina; Lobato, Luísa; Costa, Paulo M P; Fonseca, Isabel; Silva, Manuela; Bravo, Fernanda; Cabrita, António; Porto, Graça

    2007-03-01

    Familial amyloid polyneuropathy type I (FAP-I) is caused by a mutant transthyretin (TTR V30M) produced by liver, and orthotopic liver transplantation (OLT) is a widely accepted treatment for stopping the major production of TTR V30M. Anemia affects 24.8% of symptomatic FAP-I patients with low erythropoietin (Epo) levels, suggesting a blockage of Epo-producing cells by local or circulating factors. To evaluate the putative toxicity effect of the mutant protein on Epo-producing cells and consequent Epo production, clinical and laboratory parameters of 20 FAP patients were collected before and after liver transplantation, analyzed and compared. Following OLT, the prevalence of anemia increased, with a significant decrease in transferrin saturation, but without significant change in ferritin. Serum Epo levels remained low after OLT and the observed to expected (O/E) Epo level ratio decreased even further after OLT (O/E < 0.8 rose to 70%). Despite the decrease in creatinine clearance (95.1 to 66.9 ml/min, p < 0.001), a similar median O/E Epo level was observed, independently of the presence of renal failure, excluding an important impact of renal failure on Epo production. The increase of anemia after OLT and the maintenance of a defective endogenous Epo production after liver transplantation excluded an inhibitory effect of the circulating TTR V30M on the Epo-producing cells.

  13. Kurtosis-based estimation of cross-range scaling factor for high-resolution inverse synthetic aperture radar imaging

    NASA Astrophysics Data System (ADS)

    Phan, An; Ng, Brian; Tran, Hai-Tan

    2016-07-01

    In automatic target recognition systems based on the use of inverse synthetic aperture radar (ISAR) images, it is essential to obtain unbiased and accurate scaled two-dimensional target images in the range-cross range domain. To accomplish this, the modulus of the target effective rotation vector, which is generally unknown for noncooperative targets, must be estimated. This letter proposes an efficient method for estimating the cross-range scaling factor and significantly improving cross-range resolution based on the second-order local polynomial Fourier transform. The estimation requires solving a series of one-dimensional optimizations of a kurtosis objective. Simulations show the proposed approach to be effective and able to accurately estimate the scaling factor in the presence of noise.

  14. Fluorescence encoded super resolution imaging based on a location estimation algorithm for high-density fluorescence probes

    NASA Astrophysics Data System (ADS)

    Nishimura, Takahiro; Kimura, Hitoshi; Ogura, Yusuke; Tanida, Jun

    2016-11-01

    In this paper, we propose a fluorescence encoded super resolution technique based on an estimation algorithm to determine locations of high-density fluorescence emitters. In our method, several types of fluorescence coded probes are employed to reduce densities of target molecules labeled with individual codes. By applying an estimation algorithm to each coded image, the locations of the high density probes can be determined. Due to multiplexed fluorescence imaging, this approach will provide fast super resolution microscopy. In experiments, we evaluated the performance of the method using probes with different fluorescence wavelengths. Numerical simulation results show that the locations of probes with the density of 200 μ m^{-2} , which is a typical membrane-receptor expression level, are determined with acquisition of 16 different coded images.

  15. Estimates of greenhouse gas and black carbon emissions from a major Australian wildfire with high spatiotemporal resolution

    NASA Astrophysics Data System (ADS)

    Surawski, N. C.; Sullivan, A. L.; Roxburgh, S. H.; Polglase, P. J.

    2016-08-01

    Estimates of greenhouse gases and particulate emissions are made with a high spatiotemporal resolution from the Kilmore East fire in Victoria, Australia, which burnt approximately 100,000 ha over a 12 h period. Altogether, 10,175 Gigagrams (Gg) of CO2 equivalent (CO2-e) emissions occurred, with CO2 (˜68%) being the dominant chemical species emitted followed by CH4 (˜17%) and black carbon (BC) (˜15%). About 63% of total CO2-e emissions were estimated to be from coarse woody debris, 22% were from surface fuels, 7% from bark, 6% from elevated fuels, and less than 2% from tree crown consumption. To assess the quality of our emissions estimates, we compared our results with previous estimates which used the Global Fire Emissions Database version 3.1 (GFEDv3.1) and the Fire INventory from the National Center for Atmospheric Research version 1.0 (FINNv1), as well as Australia's National Inventory System (and its revision). The uncertainty in emission estimates was addressed using truncated Monte Carlo analysis, which derived a probability density function for total emissions from the uncertainties in each input. The distribution of emission estimates from Monte Carlo analysis was lognormal with a mean of 10,355 Gigagrams (Gg) and a ±1 standard deviation (σ) uncertainty range of 7260-13,450 Gg. Results were in good agreement with the global data sets (when using the same burnt area), although they predicted lower total emissions by 15-37% due to underestimating fuel consumed. Emissions estimates can be improved by obtaining better estimates of fuel consumed and BC emission factors. Overall, this study presents a methodological template for high-resolution emissions accounting and its uncertainty, enabling a step toward process-based emissions accounting to be achieved.

  16. (U) Estimating the Photonics Budget, Resolution, and Signal Requirements for a Multi-Monochromatic X-ray Imager

    SciTech Connect

    Tregillis, Ian Lee

    2016-09-22

    This document examines the performance of a generic flat-mirror multimonochromatic imager (MMI), with special emphasis on existing instruments at NIF and Omega. We begin by deriving the standard equation for the mean number of photons detected per resolution element. The pinhole energy bandwidth is a contributing factor; this is dominated by the finite size of the source and may be considerable. The most common method for estimating the spatial resolution of such a system (quadrature addition) is, technically, mathematically invalid for this case. However, under the proper circumstances it may produce good estimates compared to a rigorous calculation based on the convolution of point-spread functions. Diffraction is an important contribution to the spatial resolution. Common approximations based on Fraunhofer (farfield) diffraction may be inappropriate and misleading, as the instrument may reside in multiple regimes depending upon its configuration or the energy of interest. It is crucial to identify the correct diffraction regime; Fraunhofer and Fresnel (near-field) diffraction profiles are substantially different, the latter being considerably wider. Finally, we combine the photonics and resolution analyses to derive an expression for the minimum signal level such that the resulting images are not dominated by photon statistics. This analysis is consistent with observed performance of the NIF MMI.

  17. Estimating Temperature Retrieval Accuracy Associated With Thermal Band Spatial Resolution Requirements for Center Pivot Irrigation Monitoring and Management

    NASA Technical Reports Server (NTRS)

    Ryan, Robert E.; Irons, James; Spruce, Joseph P.; Underwood, Lauren W.; Pagnutti, Mary

    2006-01-01

    This study explores the use of synthetic thermal center pivot irrigation scenes to estimate temperature retrieval accuracy for thermal remote sensed data, such as data acquired from current and proposed Landsat-like thermal systems. Center pivot irrigation is a common practice in the western United States and in other parts of the world where water resources are scarce. Wide-area ET (evapotranspiration) estimates and reliable water management decisions depend on accurate temperature information retrieval from remotely sensed data. Spatial resolution, sensor noise, and the temperature step between a field and its surrounding area impose limits on the ability to retrieve temperature information. Spatial resolution is an interrelationship between GSD (ground sample distance) and a measure of image sharpness, such as edge response or edge slope. Edge response and edge slope are intuitive, and direct measures of spatial resolution are easier to visualize and estimate than the more common Modulation Transfer Function or Point Spread Function. For these reasons, recent data specifications, such as those for the LDCM (Landsat Data Continuity Mission), have used GSD and edge response to specify spatial resolution. For this study, we have defined a 400-800 m diameter center pivot irrigation area with a large 25 K temperature step associated with a 300 K well-watered field surrounded by an infinite 325 K dry area. In this context, we defined the benchmark problem as an easily modeled, highly common stressing case. By parametrically varying GSD (30-240 m) and edge slope, we determined the number of pixels and field area fraction that meet a given temperature accuracy estimate for 400-m, 600-m, and 800-m diameter field sizes. Results of this project will help assess the utility of proposed specifications for the LDCM and other future thermal remote sensing missions and for water resource management.

  18. Merging Radar Quantitative Precipitation Estimates (QPEs) from the High-resolution NEXRAD Reanalysis over CONUS with Rain-gauge Observations

    NASA Astrophysics Data System (ADS)

    Prat, O. P.; Nelson, B. R.; Stevens, S. E.; Nickl, E.; Seo, D. J.; Kim, B.; Zhang, J.; Qi, Y.

    2015-12-01

    The processing of radar-only precipitation via the reanalysis from the National Mosaic and Multi-Sensor Quantitative (NMQ/Q2) based on the WSR-88D Next-generation Radar (Nexrad) network over the Continental United States (CONUS) is completed for the period covering from 2002 to 2011. While this constitutes a unique opportunity to study precipitation processes at higher resolution than conventionally possible (1-km, 5-min), the long-term radar-only product needs to be merged with in-situ information in order to be suitable for hydrological, meteorological and climatological applications. The radar-gauge merging is performed by using rain gauge information at daily (Global Historical Climatology Network-Daily: GHCN-D), hourly (Hydrometeorological Automated Data System: HADS), and 5-min (Automated Surface Observing Systems: ASOS; Climate Reference Network: CRN) resolution. The challenges related to incorporating differing resolution and quality networks to generate long-term large-scale gridded estimates of precipitation are enormous. In that perspective, we are implementing techniques for merging the rain gauge datasets and the radar-only estimates such as Inverse Distance Weighting (IDW), Simple Kriging (SK), Ordinary Kriging (OK), and Conditional Bias-Penalized Kriging (CBPK). An evaluation of the different radar-gauge merging techniques is presented and we provide an estimate of uncertainty for the gridded estimates. In addition, comparisons with a suite of lower resolution QPEs derived from ground based radar measurements (Stage IV) are provided in order to give a detailed picture of the improvements and remaining challenges.

  19. Estimation of Orbital Neutron Detector Spatial Resolution by Systematic Shifting of Differential Topographic Masks

    NASA Technical Reports Server (NTRS)

    McClanahan, T. P.; Mitrofanov, I. G.; Boynton, W. V.; Chin, G.; Livengood, T.; Starr, R. D.; Evans, L. G.; Mazarico, E.; Smith, D. E.

    2012-01-01

    We present a method and preliminary results related to determining the spatial resolution of orbital neutron detectors using epithermal maps and differential topographic masks. Our technique is similar to coded aperture imaging methods for optimizing photonic signals in telescopes [I]. In that approach photon masks with known spatial patterns in a telescope aperature are used to systematically restrict incoming photons which minimizes interference and enhances photon signal to noise. Three orbital neutron detector systems with different stated spatial resolutions are evaluated. The differing spatial resolutions arise due different orbital altitudes and the use of neutron collimation techniques. 1) The uncollimated Lunar Prospector Neutron Spectrometer (LPNS) system has spatial resolution of 45km FWHM from approx. 30km altitude mission phase [2]. The Lunar Rennaissance Orbiter (LRO) Lunar Exploration Neutron Detector (LEND) with two detectors at 50km altitude evaluated here: 2) the collimated 10km FWHM spatial resolution detector CSETN and 3) LEND's collimated Sensor for Epithermal Neutrons (SETN). Thus providing two orbital altitudes to study factors of: uncollimated vs collimated and two average altitudes for their effect on fields-of-view.

  20. The effect of grid resolution on estimates of the burden of ozone and fine particulate matter on premature mortality in the United States

    PubMed Central

    Punger, Elizabeth M.; West, J. Jason

    2013-01-01

    Assessments of human health impacts associated with outdoor air pollution often use air quality models to represent exposure, but involve uncertainties due to coarse model resolution. Here we quantify how estimates of mortality in the United States attributable to ozone (O3) and fine particulate matter (PM2.5) at coarse resolution differ from those at finer resolution. Using the finest modeled concentrations (12 km), we estimate that 66,000 (95% CI, 39,300 – 84,500) all-cause and 21,400 (5,600 – 34,200) respiratory deaths per year are attributable to PM2.5 and O3 concentrations above low-concentration thresholds, respectively. Using model results at 36 km resolution gives mortality burdens that are 11% higher for PM2.5 and 12% higher for O3 than the 12 km estimates, suggesting a modest positive bias. We also scale modeled concentrations at 12 km to coarser resolutions by simple averaging, and repeat the mortality assessment at multiple resolutions from 24 to 408 km, including the resolutions of global models; in doing so, we account for the effect of resolution on population exposure. Coarse grid resolutions produce mortality estimates that are substantially biased low for PM2.5 (30–40% lower than the 12 km estimate at >250 km resolution), but less than 6% higher for O3 at any resolution. Mortality estimates for primary PM2.5 species show greater bias at coarse resolution than secondary species. These results suggest that coarse resolution global models (>100 km) are likely biased low for PM2.5 health effects. For ozone, biases due to coarse resolution may be much smaller, and the effect on modeled chemistry likely dominates. PMID:24348882

  1. Use of High-Resolution Multispectral Imagery to Estimate Chlorophyll and Plant Nitrogen in Oats (Avena sativa)

    NASA Astrophysics Data System (ADS)

    ELarab, M.; Ticlavilca, A. M.; Torres-Rua, A. F.; Maslova, I.; McKee, M.

    2013-12-01

    Precision agriculture requires high spatial resolution in the application of the inputs to agricultural production. This requires that actionable information about crop and field status be acquired at the same high spatial resolution and at a temporal frequency appropriate for timely responses. In this study, high-resolution imagery was obtained through the use of a small, unmanned aerial vehicle, called AggieAirTM, that provides spatial resolution as fine as 6 cm. Simultaneously with AggieAir flights, intensive ground sampling was conducted at precisely determined locations for plant chlorophyll, plant nitrogen, and other parameters. This study investigated the spectral signature of a crop of oats (Avena sativa) and formulated machine learning regression models of reflectance response between the multi-spectral bands available from AggieAir (red, green, blue, near infrared, and thermal), plant chlorophyll and plant nitrogen. We tested two, separate relevance vector machines (RVM) and a single multivariate relevance vector machine (MVRVM) to develop the linkages between the remotely sensed data and plant chlorophyll and nitrogen at approximately 15-cm resolution. The results of this study are presented, including a statistical evaluation of the performance of the different models and a comparison of the RVM modeling methods against more traditional approaches that have been used for estimation of plant chlorophyll and nitrogen.

  2. A high-resolution algorithm for wave number estimation using holographic array processing

    NASA Astrophysics Data System (ADS)

    Roux, Philippe; Cassereau, Didier; Roux, André

    2004-03-01

    This paper presents an original way to perform wave number inversion from simulated data obtained in a noisy shallow-water environment. In the studied configuration an acoustic source is horizontally towed with respect to a vertical hydrophone array. The inversion is achieved from the combination of three ingredients. First, a modified version of the Prony algorithm is presented and numerical comparison is made to another high-resolution wave number inversion algorithm based on the matrix-pencil technique. Second, knowing that these high-resolution algorithms are classically sensitive to noise, the use of a holographic array processing enables improvement of the signal-to-noise ratio before the inversion is performed. Last, particular care is taken in the representations of the solutions in the wave number space to improve resolution without suffering from aliasing. The dependence of this wave number inversion algorithm on the relevant parameters of the problem is discussed.

  3. The influence of spatial resolution on human health risk co-benefit estimates for global climate policy assessments.

    PubMed

    Shih, Hsiu-Ching; Crawford-Brown, Douglas; Ma, Hwong-wen

    2015-03-15

    Assessment of the ability of climate policies to produce desired improvements in public health through co-benefits of air pollution reduction can consume resources in both time and research funds. These resources increase significantly as the spatial resolution of models increases. In addition, the level of spatial detail available in macroeconomic models at the heart of climate policy assessments is much lower than that available in traditional human health risk modeling. It is therefore important to determine whether increasing spatial resolution considerably affects risk-based decisions; which kinds of decisions might be affected; and under what conditions they will be affected. Human health risk co-benefits from carbon emissions reductions that bring about concurrent reductions in Particulate Matter (PM10) emissions is therefore examined here at four levels of spatial resolution (Uniform Nation, Uniform Region, Uniform County/city, Health Risk Assessment) in a case study of Taiwan as one of the geographic regions of a global macroeceonomic model, with results that are representative of small, industrialized nations within that global model. A metric of human health risk mortality (YOLL, years of life lost in life expectancy) is compared under assessments ranging from a "uniform simulation" in which there is no spatial resolution of changes in ambient air concentration under a policy to a "highly spatially resolved simulation" (called here Health Risk Assessment). PM10 is chosen in this study as the indicator of air pollution for which risks are assessed due to its significance as a co-benefit of carbon emissions reductions within climate mitigation policy. For the policy examined, the four estimates of mortality in the entirety of Taiwan are 747 YOLL, 834 YOLL, 984 YOLL and 916 YOLL, under Uniform Taiwan, Uniform Region, Uniform County and Health Risk Assessment respectively; or differences of 18%, 9%, 7% if the HRA methodology is taken as the baseline. While

  4. Effects of 30-m nitrox saturation dive on the immune system in man.

    PubMed

    Shimamiya, T; Terada, N; Wakabayashi, S; Mohri, M

    2006-01-01

    Hyperbaria reportedly affects the immune system, but the role of psychological factors arising from confinement has not been taken into consideration. We investigated the immune changes in 4 subjects exposed to a 9-day simulated 30-m (400-kPa) nitrogen-oxygen (nitrox) saturation dive, and compared the results with those of our previous study that showed immune and mood changes in normobaric confinement. Blood samples were taken before, during, and after the dive or confinement, and activated with an anti-CD2 agonistic antibody. The percentages of granulocytes, natural killer (NK) cells, and cells positive for CD69, an early activation marker, were analyzed by flow cytometry. Reduction of CD69 expression percentage was observed under both hyperbaric and normobaric conditions. Percentages of innate immune cells, such as granulocytes and NK cells decreased or remained mostly unchanged, contrasting with our previous study, which demonstrated increases in both percentages coordinate with mood improvement. We conclude that these changes may have been triggered by suppression of sympathetic nerve activity that occurs in 30-m nitrox saturation hyperbaria.

  5. A sublittoral hard substrate epibenthic community below 30 m in head harbour passage, New Brunswick, Canada

    NASA Astrophysics Data System (ADS)

    Logan, Alan

    1988-10-01

    A sublittoral hard substrate epibenthic community has been photographically sampled mainly between depths of 30 and 140 m along two transects in Head Harbour Passage, Bay of Fundy, New Brunswick. A diverse biota of sponges, hydroids, anemones, polychaetes, brachiopods, molluscs, arthropods, echinoderms and tunicates is present throughout the depth range, but is dominated, in terms of abundance, by tubularian and campanularian hydroids, the anemone Tealia felina and the bivalve Modiolus modiolus. Cluster analysis revealed 5-6 clusters from each transect, separable on the basis of minor biological, as well as abundance, differences in the main taxa, within the depth range sampled. Abundance-depth data from each transect indicate an absence of encrusting coralline algae below 30 m and a gradual reduction in abundance of the sea urchin Strongylocentrotus droebachiensis and the brachiopod Terebratulina septentrionalis with increasing depth. In contrast, there is a gradual, but significant, increase in the abundance of tubularian hydroids, Tealia felina and Modiolus modiolus, with increasing depth. This community below about 30 m in Head Harbour Passage is here designated the Tubularia-Tealia felina-Modiolus modiolus community and forms part of the circalittoral subzone, sharing a gradational boundary with the overlying Terebratulina septentrionalis community.

  6. Total Summer Precipitation Estimated for the Early Eocene Arctic from High-Resolution Intra-ring Analyses of Fossil Wood

    NASA Astrophysics Data System (ADS)

    Schubert, B.; Jahren, A.

    2010-12-01

    During the Early Eocene (~53 - 54.5 Ma) Ellesmere Island was home to a forested ecosystem north of the Arctic Circle (ca. 76o N paleolatitude). Although several estimates exist for Eocene pCO2 levels, temperature, and relative humidity in Arctic environments, quantitative estimates of precipitation have been elusive. We present here a new method for estimating mean-annual precipitation levels from the amplitude of the annual shift in δ13C values seen across the rings of evergreen trees. Both temperature and precipitation affect the δ13C value of plant tissue, and a combination of these factors is recorded in bulk wood. Inspection of high-resolution δ13C profiles across tree-rings from nine evergreen species growing in ten different locations around the world revealed a strong relationship (R2 = 0.98) between the mean δ13C peak-height and the ratio of total summer precipitation (cm) to mean summer temperature (oC). Application of this relationship to nearly 700 measurements of δ13C in bulk wood from high-resolution (i.e., ~40 µm) sampling of evergreen fossil wood, in combination with temperature estimates from geochemical proxies, yielded estimates for total summer precipitation in excess of 90 cm. These conditions are considerably wetter than evergreen forests found at today's mid-latitudes (e.g., the pine forests of Siberia have ~30 cm of total summer precipitation; the spruce forests of Germany and Northern Italy have ~40 - 60 cm of total summer precipitation). We compare our results to Eocene paleoprecipitation estimates based on leaf area analysis of fossil leaves collected from similar sites and discuss the implications for global water transport.

  7. Vineyard Yield Estimation Based on the Analysis of High Resolution Images Obtained with Artificial Illumination at Night

    PubMed Central

    Font, Davinia; Tresanchez, Marcel; Martínez, Dani; Moreno, Javier; Clotet, Eduard; Palacín, Jordi

    2015-01-01

    This paper presents a method for vineyard yield estimation based on the analysis of high-resolution images obtained with artificial illumination at night. First, this paper assesses different pixel-based segmentation methods in order to detect reddish grapes: threshold based, Mahalanobis distance, Bayesian classifier, linear color model segmentation and histogram segmentation, in order to obtain the best estimation of the area of the clusters of grapes in this illumination conditions. The color spaces tested were the original RGB and the Hue-Saturation-Value (HSV). The best segmentation method in the case of a non-occluded reddish table-grape variety was the threshold segmentation applied to the H layer, with an estimation error in the area of 13.55%, improved up to 10.01% by morphological filtering. Secondly, after segmentation, two procedures for yield estimation based on a previous calibration procedure have been proposed: (1) the number of pixels corresponding to a cluster of grapes is computed and converted directly into a yield estimate; and (2) the area of a cluster of grapes is converted into a volume by means of a solid of revolution, and this volume is converted into a yield estimate; the yield errors obtained were 16% and −17%, respectively. PMID:25860071

  8. Vineyard yield estimation based on the analysis of high resolution images obtained with artificial illumination at night.

    PubMed

    Font, Davinia; Tresanchez, Marcel; Martínez, Dani; Moreno, Javier; Clotet, Eduard; Palacín, Jordi

    2015-04-09

    This paper presents a method for vineyard yield estimation based on the analysis of high-resolution images obtained with artificial illumination at night. First, this paper assesses different pixel-based segmentation methods in order to detect reddish grapes: threshold based, Mahalanobis distance, Bayesian classifier, linear color model segmentation and histogram segmentation, in order to obtain the best estimation of the area of the clusters of grapes in this illumination conditions. The color spaces tested were the original RGB and the Hue-Saturation-Value (HSV). The best segmentation method in the case of a non-occluded reddish table-grape variety was the threshold segmentation applied to the H layer, with an estimation error in the area of 13.55%, improved up to 10.01% by morphological filtering. Secondly, after segmentation, two procedures for yield estimation based on a previous calibration procedure have been proposed: (1) the number of pixels corresponding to a cluster of grapes is computed and converted directly into a yield estimate; and (2) the area of a cluster of grapes is converted into a volume by means of a solid of revolution, and this volume is converted into a yield estimate; the yield errors obtained were 16% and -17%, respectively.

  9. Estimation of position resolution for DOI-PET detector using diameter 0.2 mm WLS fibers

    SciTech Connect

    Kaneko, Naomi; Ito, Hiroshi; Kawai, Hideyuki; Kamada, Kei

    2015-07-01

    We have been developing sub mm resolution and $ 1 million DOI-PET detector using wavelength shifting fibers (WLSF), scintillation crystals of plate shape and SiPM (MPPC: HAMAMATSU K. K.). Conventional design of DOI-PET detector is obtained about mm{sup 3} of resolution by using some blocks detecting gamma-ray in mm 3 voxel. It requires the production cost of $ a few ten million or more for high technique of processing crystal and a lot of number of photo-devices, and this technology is reaching the limit of the resolution. Both higher resolution and lower cost of DOI-PET detector production is challenging for PET diagnosis population. We propose two type of detector. One is a whole body PET system, and the other for brain or small animal. Both PET system consist 6 blocks. the former consist of 6 layers 300 mm x 300 mm x 4 mm crystal plate. The latter consist 16 crystal layers, 4 x 4 crystal array. The size of crystal plate is 40 mm x 40 mm x 1 mm.The WLSF sheets connect to upper and lower plane. The whole PET systems connect 8 SiPMs are bonded on each side. For the brain PET, 9 WLSF fibers are bond on the each side. The expected position resolution maybe less than 1 mm at the former. We have estimation experimental performance the system using {sup 22}Na radioactive source. The collection efficiency of WLSF (R-3) sheet was achieved 10% with GAGG at 511 keV. The relation between reconstruction position and incident position is obtained linearity and achieved the resolution of 0.7 mm FWHM for x-axis of DOI by readout WLSF. (authors)

  10. Experimental Estimation of CLASP Spatial and Spectral Resolutions: Results of the Instrument's Optical Alignment

    NASA Technical Reports Server (NTRS)

    Giono, G.; Katsukawa, Y.; Ishikawa, R.; Narukage, N.; Bando, T.; Kano, R.; Suematsu, Y.; Winebarger, A.; Kobayashi, K.; Auchere, F.

    2015-01-01

    The Chromospheric Lyman-Alpha SpectroPolarimeter is a sounding rocket experiment design to measure for the first time the polarization signal of the Lyman-Alpha line (121.6nm), emitted in the solar upper-chromosphere and transition region. This instrument aims to detect the Hanle effect's signature hidden in the Ly-alpha polarization, as a tool to probe the chromospheric magnetic field. Hence, an unprecedented polarization accuracy is needed ((is) less than 10 (exp -3). Nevertheless, spatial and spectral resolutions are also crucial to observe chhromospheric feature such as spicules, and to have precise measurement of the Ly-alpha line core and wings. Hence, this poster will present how the telescope and the spectrograph were separately aligned, and their combined spatial and spectral resolutions.

  11. Kalman-filtered compressive sensing for high resolution estimation of anthropogenic greenhouse gas emissions from sparse measurements.

    SciTech Connect

    Ray, Jaideep; Lee, Jina; Lefantzi, Sophia; Yadav, Vineet; Michalak, Anna M.; van Bloemen Waanders, Bart Gustaaf; McKenna, Sean Andrew

    2013-09-01

    The estimation of fossil-fuel CO2 emissions (ffCO2) from limited ground-based and satellite measurements of CO2 concentrations will form a key component of the monitoring of treaties aimed at the abatement of greenhouse gas emissions. The limited nature of the measured data leads to a severely-underdetermined estimation problem. If the estimation is performed at fine spatial resolutions, it can also be computationally expensive. In order to enable such estimations, advances are needed in the spatial representation of ffCO2 emissions, scalable inversion algorithms and the identification of observables to measure. To that end, we investigate parsimonious spatial parameterizations of ffCO2 emissions which can be used in atmospheric inversions. We devise and test three random field models, based on wavelets, Gaussian kernels and covariance structures derived from easily-observed proxies of human activity. In doing so, we constructed a novel inversion algorithm, based on compressive sensing and sparse reconstruction, to perform the estimation. We also address scalable ensemble Kalman filters as an inversion mechanism and quantify the impact of Gaussian assumptions inherent in them. We find that the assumption does not impact the estimates of mean ffCO2 source strengths appreciably, but a comparison with Markov chain Monte Carlo estimates show significant differences in the variance of the source strengths. Finally, we study if the very different spatial natures of biogenic and ffCO2 emissions can be used to estimate them, in a disaggregated fashion, solely from CO2 concentration measurements, without extra information from products of incomplete combustion e.g., CO. We find that this is possible during the winter months, though the errors can be as large as 50%.

  12. Improved EEG source analysis using low-resolution conductivity estimation in a four-compartment finite element head model.

    PubMed

    Lew, Seok; Wolters, Carsten H; Anwander, Alfred; Makeig, Scott; MacLeod, Rob S

    2009-09-01

    Bioelectric source analysis in the human brain from scalp electroencephalography (EEG) signals is sensitive to geometry and conductivity properties of the different head tissues. We propose a low-resolution conductivity estimation (LRCE) method using simulated annealing optimization on high-resolution finite element models that individually optimizes a realistically shaped four-layer volume conductor with regard to the brain and skull compartment conductivities. As input data, the method needs T1- and PD-weighted magnetic resonance images for an improved modeling of the skull and the cerebrospinal fluid compartment and evoked potential data with high signal-to-noise ratio (SNR). Our simulation studies showed that for EEG data with realistic SNR, the LRCE method was able to simultaneously reconstruct both the brain and the skull conductivity together with the underlying dipole source and provided an improved source analysis result. We have also demonstrated the feasibility and applicability of the new method to simultaneously estimate brain and skull conductivity and a somatosensory source from measured tactile somatosensory-evoked potentials of a human subject. Our results show the viability of an approach that computes its own conductivity values and thus reduces the dependence on assigning values from the literature and likely produces a more robust estimate of current sources. Using the LRCE method, the individually optimized four-compartment volume conductor model can, in a second step, be used for the analysis of clinical or cognitive data acquired from the same subject.

  13. Detecting tents to estimate the displaced populations for post-disaster relief using high resolution satellite imagery

    NASA Astrophysics Data System (ADS)

    Wang, Shifeng; So, Emily; Smith, Pete

    2015-04-01

    Estimating the number of refugees and internally displaced persons is important for planning and managing an efficient relief operation following disasters and conflicts. Accurate estimates of refugee numbers can be inferred from the number of tents. Extracting tents from high-resolution satellite imagery has recently been suggested. However, it is still a significant challenge to extract tents automatically and reliably from remote sensing imagery. This paper describes a novel automated method, which is based on mathematical morphology, to generate a camp map to estimate the refugee numbers by counting tents on the camp map. The method is especially useful in detecting objects with a clear shape, size, and significant spectral contrast with their surroundings. Results for two study sites with different satellite sensors and different spatial resolutions demonstrate that the method achieves good performance in detecting tents. The overall accuracy can be up to 81% in this study. Further improvements should be possible if over-identified isolated single pixel objects can be filtered. The performance of the method is impacted by spectral characteristics of satellite sensors and image scenes, such as the extent of area of interest and the spatial arrangement of tents. It is expected that the image scene would have a much higher influence on the performance of the method than the sensor characteristics.

  14. Satellite-driven estimation of terrestrial carbon flux over Far East Asia with 30-second grid resolution

    NASA Astrophysics Data System (ADS)

    Sasai, T.; Saigusa, N.; Nasahara, K. N.; Ito, A.; Hashimoto, H.; Nemani, R. R.; Hirata, R.; Ichii, K.; Takagi, K.; Saitoh, T. M.; Ohta, T.; Murakami, K.; Oikawa, T.; Yamaguchi, Y.

    2010-12-01

    The terrestrial carbon cycle is strongly affected by local natural phenomena and local human-induced activities that alter carbon exchange via vegetation and soil activities. In order to accurately understand terrestrial carbon cycle mechanisms, it is necessary to estimate spatial and temporal variations in carbon flux and storage using process-based models with the highest possible resolution. We estimated terrestrial carbon fluxes using the biosphere model integrating eco-physiological and mechanistic approaches using Satellite data (BEAMS) and satellite observations with 30-second grid resolution. The study area is the central Far East Asia region, which lies between 30 degree and 50 degree north latitude and 125 degree and 150 degree east longitude. Aiming to simulate terrestrial carbon exchanges under realistic land surface conditions, we applied as many satellite-observation means as possible, such as the standard MODIS, TRMM, and SRTM high-level land products. Validated using gross primary productivity (GPP), net ecosystem production (NEP), net radiation and latent heat with ground measurements at six flux sites, the model estimations showed reasonable seasonal and annual patterns. In extensive analysis, total amounts of GPP and NPP were determined to be 2.1 PgC/year and 0.9 PgC/year. The total NEP estimate was +5.6 TgC/year, meaning that the land area played a role as a carbon sink for these six years. In analyses of areas with complicated topography, the 30-second grid estimation could prove to be an effective product to evaluate the effect of landscape on the terrestrial carbon cycle. The method presented here is an appropriate approach to gain a better understanding of terrestrial carbon exchange, both spatially and temporally.

  15. GPS-based estimation of sub-daily and rapid polar motion at 15-minute temporal resolution

    NASA Astrophysics Data System (ADS)

    Sibois, Aurore; Bertiger, Willy; Desai, Shailen; Haines, Bruce

    2015-04-01

    We present results from the homogeneous re-analysis of ten years of data from a global Global Positioning System (GPS) network specifically targeting the recovery of the Earth's pole coordinates at 15-minute temporal resolution. We deliberately treat prograde semidiurnal nutation as retrograde diurnal polar motion in our parameter estimation strategy in order to gain insight into potential deficiencies in the sets of precession and nutation models applied. Doing so, we are able to retrieve meaningful polar motion signal in the retrograde diurnal frequency band. This leads us to evaluate the coupling between models of precession-nutation and diurnal variations on polar motion from the ocean tides on total observed polar motion. To assess the quality of our polar motion solution outside of the retrograde diurnal frequency band, we focus on its capability to recover tidally driven and non-tidal variations manifesting at the ultra-rapid (intra-daily) and rapid (characterized by periods ranging from 2 to 20 days) periods. We first evaluate the fit of our polar motion estimates to the IERS 2010 recommended model. This tidal analysis reveals discrepancies manifesting at specific tidal periods and stresses difficulties in separating technique-specific errors and estimation strategy artifacts from model errors. We discuss some of these error sources. After accounting for the effects of diurnal and semi-diurnal ocean tides in our estimation procedure, we convert our series of pole coordinates into the excitation formalism and contrast the resulting series with independently obtained geodynamic excitation functions. We demonstrate that increasing the temporal resolution does not compromise the fidelity of our estimates to predicted rapid variations in polar motion caused by the oceanic and atmospheric circulations. Our results infer a noise level of about 4 μas from our decade-long time series.

  16. Use of ultra-high spatial resolution aerial imagery in the estimation of chaparral wildfire fuel loads.

    PubMed

    Schmidt, Ian T; O'Leary, John F; Stow, Douglas A; Uyeda, Kellie A; Riggan, Phillip J

    2016-12-01

    Development of methods that more accurately estimate spatial distributions of fuel loads in shrublands allows for improved understanding of ecological processes such as wildfire behavior and postburn recovery. The goal of this study is to develop and test remote sensing methods to upscale field estimates of shrubland fuel to broader-scale biomass estimates using ultra-high spatial resolution imagery captured by a light-sport aircraft. The study is conducted on chaparral shrublands located in eastern San Diego County, CA, USA. We measured the fuel load in the field using a regression relationship between basal area and aboveground biomass of shrubs and estimated ground areal coverage of individual shrub species by using ultra-high spatial resolution imagery and image processing routines. Study results show a strong relationship between image-derived shrub coverage and field-measured fuel loads in three even-age stands that have regrown approximately 7, 28, and 68 years since last wildfire. We conducted ordinary least square analysis using ground coverage as the independent variable regressed against biomass. The analysis yielded R (2) values ranging from 0.80 to 0.96 in the older stands for the live shrub species, while R (2) values for species in the younger stands ranged from 0.32 to 0.89. Pooling species-based data into larger sample sizes consisting of a functional group and all-shrub classes while obtaining suitable linear regression models supports the potential for these methods to be used for upscaling fuel estimates to broader areal extents, without having to classify and map shrubland vegetation at the species level.

  17. Towards High Spa-Temporal Resolution Estimates of Surface Radiative Fluxes from Geostationary Satellite Observations for the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Niu, X.; Yang, K.; Tang, W.; Qin, J.

    2014-12-01

    Surface Solar Radiation (SSR) plays an important role of the hydrological and land process modeling, which particularly contributes more than 90% to the total melt energy for the Tibetan Plateau (TP) ice melting. Neither surface measurement nor existing remote sensing products can meet that requirement in TP. The well-known satellite products (i.e. ISCCP-FD and GEWEX-SRB) are in relatively low spatial resolution (0.5º-2.5º) and temporal resolution (3-hourly, daily, or monthly). The objective of this study is to develop capabilities to improved estimates of SSR in TP based on geostationary satellite observations from the Multi-functional Transport Satellite (MTSAT) with high spatial (0.05º) and temporal (hourly) resolution. An existing physical model, the UMD-SRB (University of Maryland Surface Radiation Budget) which is the basis of the GEWEX-SRB model, is re-visited to improve SSR estimates in TP. The UMD-SRB algorithm transforms TOA radiances into broadband albedos in order to infer atmospheric transmissivity which finally determines the SSR. Specifically, main updates introduced in this study are: implementation at 0.05º spatial resolution at hourly intervals integrated to daily and monthly time scales; and improvement of surface albedo model by introducing the most recently developed Global Land Surface Broadband Albedo Product (GLASS) based on MODIS data. This updated inference scheme will be evaluated against ground observations from China Meteorological Administration (CMA) radiation stations and three TP radiation stations contributed from the Institute of Tibetan Plateau Research.

  18. Estimating daily air temperature across the Southeastern United States using high-resolution satellite data: a statistical modeling study

    PubMed Central

    Shi, Liuhua; Liu, Pengfei; Kloog, Itai; Lee, Mihye; Kosheleva, Anna; Schwartz, Joel

    2015-01-01

    Accurate estimates of spatio-temporal resolved near-surface air temperature (Ta) are crucial for environmental epidemiological studies. However, values of Ta are conventionally obtained from weather stations, which have limited spatial coverage. Satellite surface temperature (Ts) measurements offer the possibility of local exposure estimates across large domains. The Southeastern United States has different climatic conditions, more small water bodies and wetlands, and greater humidity in contrast to other regions, which add to the challenge of modeling air temperature. In this study, we incorporated satellite Ts to estimate high resolution (1 km × 1 km) daily Ta across the southeastern USA for 2000-2014. We calibrated Ts to Ta measurements using mixed linear models, land use, and separate slopes for each day. A high out-of-sample cross-validated R2 of 0.952 indicated excellent model performance. When satellite Ts were unavailable, linear regression on nearby monitors and spatio-temporal smoothing was used to estimate Ta. The daily Ta estimations were compared to the NASA's Modern-Era Retrospective Analysis for Research and Applications (MERRA) model. A good agreement with an R2 of 0.969 and a mean squared prediction error (RMSPE) of 1.376 °C was achieved. Our results demonstrate that Ta can be reliably predicted using this Ts-based prediction model, even in a large geographical area with topography and weather patterns varying considerably. PMID:26717080

  19. Estimating daily air temperature across the Southeastern United States using high-resolution satellite data: A statistical modeling study.

    PubMed

    Shi, Liuhua; Liu, Pengfei; Kloog, Itai; Lee, Mihye; Kosheleva, Anna; Schwartz, Joel

    2016-04-01

    Accurate estimates of spatio-temporal resolved near-surface air temperature (Ta) are crucial for environmental epidemiological studies. However, values of Ta are conventionally obtained from weather stations, which have limited spatial coverage. Satellite surface temperature (Ts) measurements offer the possibility of local exposure estimates across large domains. The Southeastern United States has different climatic conditions, more small water bodies and wetlands, and greater humidity in contrast to other regions, which add to the challenge of modeling air temperature. In this study, we incorporated satellite Ts to estimate high resolution (1km×1km) daily Ta across the southeastern USA for 2000-2014. We calibrated Ts-Ta measurements using mixed linear models, land use, and separate slopes for each day. A high out-of-sample cross-validated R(2) of 0.952 indicated excellent model performance. When satellite Ts were unavailable, linear regression on nearby monitors and spatio-temporal smoothing was used to estimate Ta. The daily Ta estimations were compared to the NASA's Modern-Era Retrospective Analysis for Research and Applications (MERRA) model. A good agreement with an R(2) of 0.969 and a mean squared prediction error (RMSPE) of 1.376°C was achieved. Our results demonstrate that Ta can be reliably predicted using this Ts-based prediction model, even in a large geographical area with topography and weather patterns varying considerably.

  20. Analysis of solar radiation on the surface estimated from GWNU solar radiation model with temporal resolution of satellite cloud fraction

    NASA Astrophysics Data System (ADS)

    Zo, Il-Sung; Jee, Joon-Bum; Lee, Kyu-Tae; Kim, Bu-Yo

    2016-08-01

    Preliminary analysis with a solar radiation model is generally performed for photovoltaic power generation projects. Therefore, model accuracy is extremely important. The temporal and spatial resolutions used in previous studies of the Korean Peninsula were 1 km × 1 km and 1-h, respectively. However, calculating surface solar radiation at 1-h intervals does not ensure the accuracy of the geographical effects, and this parameter changes owing to atmospheric elements (clouds, aerosol, ozone, etc.). Thus, a change in temporal resolution is required. In this study, one-year (2013) analysis was conducted using Chollian geostationary meteorological satellite data from observations recorded at 15-min intervals. Observation data from the intensive solar site at Gangneung-Wonju National University (GWNU) showed that the coefficient of determination (R²), which was estimated for each month and season, increased, whereas the standard error (SE) decreased when estimated in 15-min intervals over those obtained in 1-h intervals in 2013. When compared with observational data from 22 solar sites of the Korean Meteorological Administration (KMA), R2 was 0.9 or higher on average, and over- or under-simulated sites did not exceed 3 sites. The model and 22 solar sites showed similar values of annual accumulated solar irradiation, and their annual mean was similar at 4,998 MJ m-2 (3.87 kWh m-2). These results show a difference of approximately ± 70 MJ m-2 (± 0.05 kWh m-2) from the distribution of the Korean Peninsula estimated in 1-h intervals and a higher correlation at higher temporal resolution.

  1. A real-time smart sensor for high-resolution frequency estimation in power systems.

    PubMed

    Granados-Lieberman, David; Romero-Troncoso, Rene J; Cabal-Yepez, Eduardo; Osornio-Rios, Roque A; Franco-Gasca, Luis A

    2009-01-01

    Power quality monitoring is a theme in vogue and accurate frequency measurement of the power line is a major issue. This problem is particularly relevant for power generating systems since the generated signal must comply with restrictive standards. The novelty of this work is the development of a smart sensor for real-time high-resolution frequency measurement in accordance with international standards for power quality monitoring. The proposed smart sensor utilizes commercially available current clamp, hall-effect sensor or resistor as primary sensor. The signal processing is carried out through the chirp z-transform. Simulations and experimental results show the efficiency of the proposed smart sensor.

  2. Comparing LAI estimates of corn and soybean from vegetation indices of multi-resolution satellite images

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leaf area index (LAI) is important in explaining the ability of the crop to intercept solar energy for biomass production and in understanding the impact of crop management practices. This paper describes a procedure for estimating LAI as a function of image-derived vegetation indices from temporal ...

  3. Improved accuracy of quantitative parameter estimates in dynamic contrast-enhanced CT study with low temporal resolution

    SciTech Connect

    Kim, Sun Mo; Jaffray, David A.

    2016-01-15

    Purpose: A previously proposed method to reduce radiation dose to patient in dynamic contrast-enhanced (DCE) CT is enhanced by principal component analysis (PCA) filtering which improves the signal-to-noise ratio (SNR) of time-concentration curves in the DCE-CT study. The efficacy of the combined method to maintain the accuracy of kinetic parameter estimates at low temporal resolution is investigated with pixel-by-pixel kinetic analysis of DCE-CT data. Methods: The method is based on DCE-CT scanning performed with low temporal resolution to reduce the radiation dose to the patient. The arterial input function (AIF) with high temporal resolution can be generated with a coarsely sampled AIF through a previously published method of AIF estimation. To increase the SNR of time-concentration curves (tissue curves), first, a region-of-interest is segmented into squares composed of 3 × 3 pixels in size. Subsequently, the PCA filtering combined with a fraction of residual information criterion is applied to all the segmented squares for further improvement of their SNRs. The proposed method was applied to each DCE-CT data set of a cohort of 14 patients at varying levels of down-sampling. The kinetic analyses using the modified Tofts’ model and singular value decomposition method, then, were carried out for each of the down-sampling schemes between the intervals from 2 to 15 s. The results were compared with analyses done with the measured data in high temporal resolution (i.e., original scanning frequency) as the reference. Results: The patients’ AIFs were estimated to high accuracy based on the 11 orthonormal bases of arterial impulse responses established in the previous paper. In addition, noise in the images was effectively reduced by using five principal components of the tissue curves for filtering. Kinetic analyses using the proposed method showed superior results compared to those with down-sampling alone; they were able to maintain the accuracy in the

  4. Multi-scale geospatial agroecosystem modeling: a case study on the influence of soil data resolution on carbon budget estimates

    SciTech Connect

    Zhang, Xuesong; Sahajpal, Ritvik; Manowitz, D.; Zhao, Kaiguang; LeDuc, Stephen D.; Xu, Min; Xiong, Wei; Zhang, Aiping; Izaurralde, Roberto C.; Thomson, Allison M.; West, Tristram O.; Post, W. M.

    2014-05-01

    The development of effective measures to stabilize atmospheric CO2 concentration and mitigate negative impacts of climate change requires accurate quantification of the spatial variation and magnitude of the terrestrial carbon (C) flux. However, the spatial pattern and strength of terrestrial C sinks and sources remain uncertain. In this study, we designed a spatially-explicit agroecosystem modeling system by integrating the Environmental Policy Integrated Climate (EPIC) model with multiple sources of geospatial and surveyed datasets (including crop type map, elevation, climate forcing, fertilizer application, tillage type and distribution, and crop planting and harvesting date), and applied it to examine the sensitivity of cropland C flux simulations to two widely used soil databases (i.e. State Soil Geographic-STATSGO of a scale of 1:250,000 and Soil Survey Geographic-SSURGO of a scale of 1:24,000) in Iowa, USA. To efficiently execute numerous EPIC runs resulting from the use of high resolution spatial data (56m), we developed a parallelized version of EPIC. Both STATSGO and SSURGO led to similar simulations of crop yields and Net Ecosystem Production (NEP) estimates at the State level. However, substantial differences were observed at the county and sub-county (grid) levels. In general, the fine resolution SSURGO data outperformed the coarse resolution STATSGO data for county-scale crop-yield simulation, and within STATSGO, the area-weighted approach provided more accurate results. Further analysis showed that spatial distribution and magnitude of simulated NEP were more sensitive to the resolution difference between SSURGO and STATSGO at the county or grid scale. For over 60% of the cropland areas in Iowa, the deviations between STATSGO- and SSURGO-derived NEP were larger than 1MgCha(-1)yr(-1), or about half of the average cropland NEP, highlighting the significant uncertainty in spatial distribution and magnitude of simulated C fluxes resulting from

  5. Resolution of deep angiosperm phylogeny using conserved nuclear genes and estimates of early divergence times

    PubMed Central

    Zeng, Liping; Zhang, Qiang; Sun, Renran; Kong, Hongzhi; Zhang, Ning; Ma, Hong

    2014-01-01

    Angiosperms are the most successful plants and support human livelihood and ecosystems. Angiosperm phylogeny is the foundation of studies of gene function and phenotypic evolution, divergence time estimation and biogeography. The relationship of the five divergent groups of the Mesangiospermae (~99.95% of extant angiosperms) remains uncertain, with multiple hypotheses reported in the literature. Here transcriptome data sets are obtained from 26 species lacking sequenced genomes, representing each of the five groups: eudicots, monocots, magnoliids, Chloranthaceae and Ceratophyllaceae. Phylogenetic analyses using 59 carefully selected low-copy nuclear genes resulted in highly supported relationships: sisterhood of eudicots and a clade containing Chloranthaceae and Ceratophyllaceae, with magnoliids being the next sister group, followed by monocots. Our topology allows a re-examination of the evolutionary patterns of 110 morphological characters. The molecular clock estimates of Mesangiospermae diversification during the late to middle Jurassic correspond well to the origins of some insects, which may have been a factor facilitating early angiosperm radiation. PMID:25249442

  6. Resolution of deep angiosperm phylogeny using conserved nuclear genes and estimates of early divergence times.

    PubMed

    Zeng, Liping; Zhang, Qiang; Sun, Renran; Kong, Hongzhi; Zhang, Ning; Ma, Hong

    2014-09-24

    Angiosperms are the most successful plants and support human livelihood and ecosystems. Angiosperm phylogeny is the foundation of studies of gene function and phenotypic evolution, divergence time estimation and biogeography. The relationship of the five divergent groups of the Mesangiospermae (~99.95% of extant angiosperms) remains uncertain, with multiple hypotheses reported in the literature. Here transcriptome data sets are obtained from 26 species lacking sequenced genomes, representing each of the five groups: eudicots, monocots, magnoliids, Chloranthaceae and Ceratophyllaceae. Phylogenetic analyses using 59 carefully selected low-copy nuclear genes resulted in highly supported relationships: sisterhood of eudicots and a clade containing Chloranthaceae and Ceratophyllaceae, with magnoliids being the next sister group, followed by monocots. Our topology allows a re-examination of the evolutionary patterns of 110 morphological characters. The molecular clock estimates of Mesangiospermae diversification during the late to middle Jurassic correspond well to the origins of some insects, which may have been a factor facilitating early angiosperm radiation.

  7. Super-resolution techniques for velocity estimation using UWB random noise radar signals

    NASA Astrophysics Data System (ADS)

    Dawood, Muhammad; Quraishi, Nafish; Alejos, Ana V.

    2011-06-01

    The Doppler spread pertaining to the ultrawideband (UWB) radar signals from moving target is directly proportional to the bandwidth of the transmitted signal and the target velocity. Using typical FFT-based methods, the estimation of true velocities pertaining to two targets moving with relatively close velocities within a radar range bin is problematic. In this paper, we extend the Multiple Signal Classification (MUSIC) algorithm to resolve targets moving velocities closer to each other within a given range bin for UWB random noise radar waveforms. Simulated and experimental results are compared for various target velocities using both narrowband (200MHz) and wideband (1GHz) noise radar signals, clearly establishing the unbiased and unambiguous velocity estimations using the MUSIC algorithm.

  8. Estimation of heat and freshwater transports in the North Pacific using high-resolution expendable bathythermograph data

    NASA Astrophysics Data System (ADS)

    Uehara, Hiroki; Kizu, Shoichi; Hanawa, Kimio; Yoshikawa, Yasushi; Roemmich, Dean

    2008-02-01

    The mean heat and freshwater transports in the North Pacific subtropical gyre during 1998-2002 are estimated. High-resolution expendable bathythermograph/expendable conductivity-temperature-depth (XBT/XCTD) transects (PX-40, Honolulu to Japan; PX-37, San Francisco to Honolulu; PX-10, Honolulu to Guam; PX-44, Guam to Taiwan/Hong Kong) are used to calculate geostrophic transport across each of the ship tracks. Ekman transport is estimated from satellite-scatterometer wind stress. The mean heat and freshwater transport convergences into the northern box bounded by the PX-40/37 transects and the Tsushima and Bering Straits are 0.26 ± 0.16 pW (pW = 1015 W) and -0.26 ± 0.11 Sv (Sv = 106 m3/s), respectively. Heat and freshwater transport convergences into the western box bounded by the PX-40/10/44 transects and the Tsushima Strait are estimated to be 0.32 ± 0.17 pW and 0.08 ± 0.07 Sv, respectively. In both boxes, warmer waters transported inward by the Ekman flow and by the Kuroshio are compensated by the export of waters at cooler temperatures, whose peaks are found in the temperatures of the mode waters formed in the North Pacific. The salt budget is also described to consider the mechanisms of freshwater transport. Since the western box includes the region with the strongest heat loss to the atmosphere and is possibly a key region for climatic decadal variation, it is necessary to continue the high-resolution XBT/XCTD measurement and to make an effort at improving the estimation of heat and freshwater transports in order to contribute to advancing climate studies.

  9. Assessing the horizontal refraction of ocean acoustic tomography signals using high-resolution ocean state estimates.

    PubMed

    Dushaw, Brian D

    2014-07-01

    The analysis of signals for acoustic tomography sent between a source and a receiver most often uses the unrefracted geodesic path, an approximation that is justified from theoretical considerations, relying on estimates of horizontal gradients of sound speed, or on simple theoretical models. To quantify the effects of horizontal refraction caused by a realistic ocean environment, horizontal refractions of long-range signals were computed using global ocean state estimates for 2004 from the Estimating the Circulation and Climate of the Ocean (ECCO2) project. Basin-scale paths in the eastern North Pacific Ocean and regional-scale paths in the Philippine Sea were used as examples. At O(5 Mm) basin scales, refracted geodesic and geodesic paths differed by only about 5 km. Gyre-scale features had the greatest refractive influence, but the precise refractive effects depended on the path geometry with respect to oceanographic features. Refraction decreased travel times by 5-10 ms and changed azimuthal angles by about 0.2°. At O(500 km) regional scales, paths deviated from the geodesic by only 250 m, and travel times deviated by less than 0.5 ms. Such effects are of little consequence in the analysis of tomographic data. Refraction details depend only slightly on mode number and frequency.

  10. Temporal resolution limit estimation of x-ray streak cameras using a CsI photocathode

    SciTech Connect

    Li, Xiang; Gu, Li; Zong, Fangke; Zhang, Jingjin; Yang, Qinlao

    2015-08-28

    A Monte Carlo model is developed and implemented to calculate the characteristics of x-ray induced secondary electron (SE) emission from a CsI photocathode used in an x-ray streak camera. Time distributions of emitted SEs are investigated with an incident x-ray energy range from 1 to 30 keV and a CsI thickness range from 100 to 1000 nm. Simulation results indicate that SE time distribution curves have little dependence on the incident x-ray energy and CsI thickness. The calculated time dispersion within the CsI photocathode is about 70 fs, which should be the temporal resolution limit of x-ray streak cameras that use CsI as the photocathode material.

  11. Application of high-resolution passive seismic tomographic inversion and estimating reservoir properties

    NASA Astrophysics Data System (ADS)

    Ayatollahy Tafti, T.; Aminzadeh, F.

    2011-12-01

    We use the travel time information from micro-seismic events of the micro earthquake data to perform tomographic inversion to accurately estimate P wave and S wave velocities. These velocities lead us to structural and lithological information about the subsurface. We test the method using the MEQ data from the NW Geysers geothermal field for both velocity inversion and estimating the reservoir properties. Complementary geophysical data are helpful for imaging the sub-surface structure. We integrate the available geologic information with the MEQ data. Porosity, fracture density and permeability are some of the properties that we extract from our integrated method. In addition, we quantify the changes of the velocities with time in parts of the field; we then ascribe such changes to various phenomena of transient geological processes such as, dyke intrusions or fluid pressure increase in the fracture network or even fracture network propagation into the medium. We demonstrate that integrating the passive seismic tomography with geologic information allows us to detect the space-time dependency of elastic properties in response to local variations of fluid pressure. We use the seismicity data set as a geothermal reservoir monitoring tool for mapping the fluid movements and other changes in reservoir properties. Our results are consistent with both injection and production well data. We focus on two sub-regions for our investigation. One region corresponds to a traditional hydrothermal reservoir. The second region relates to a high temperature zone, a candidate for creation of Enhanced Geothermal System (EGS) project. These results show the importance of integration of passive seismic tomography with geologic information for estimating the geothermal reservoir properties where sufficient microseismicity is present.

  12. Estimation of porphyrin concentration in the kerogen fraction of shales using high-resolution reflectance spectroscopy

    NASA Technical Reports Server (NTRS)

    Holden, Peter N.; Gaffey, Michael J.; Sundararaman, P.

    1991-01-01

    An interpretive model for estimating porphyrin concentration in bitumen and kerogen from spectral reaflectance data in the visible and near-ultraviolet region of the spectrum is derived and calibrated. Preliminary results obtained using the model are consistent with concentrations determined from the bitumen extract and suggest that 40 to 60 percent of the total porphyrin concentration remains in the kerogen after extraction of bitumen from thermally immature samples. The reflectance technique will contribute to porphyrin and kerogen studies and can be applied at its present level of development to several areas of geologic and paleo-oceanographic research.

  13. Estimation of Trees Outside Forests using IRS High Resolution data by Object Based Image Analysis

    NASA Astrophysics Data System (ADS)

    Pujar, G. S.; Reddy, P. M.; Reddy, C. S.; Jha, C. S.; Dadhwal, V. K.

    2014-11-01

    Assessment of Trees outside forests (TOF) is widely being recognized as a pivotal theme, in sustainable natural resource management, due to their role in offering variety of goods, such as timber, fruits and fodder as well as services like water, carbon, biodiversity. Forest Conservation efforts involving reduction of deforestation and degradation may have to increasingly rely on alternatives provided by TOF in catering to economic demands in forest edges. Spatial information systems involving imaging, analysis and monitoring to achieve objectives under protocols like REDD+, require incorporation of information content from areas under forest as well as trees outside forests, to aid holistic decisions. In this perspective, automation in retrieving information on area under trees, growing outside forests, using high resolution imaging is essential so that measuring and verification of extant carbon pools, are strengthened. Retrieval of this tree cover is demonstrated herewith, using object based image analysis in a forest edge of dry deciduous forests of Eastern Ghats, in Khammam district of Telangana state of India. IRS high resolution panchromatic 2.5 m data (Cartosat-1 Orthorectified) used in tandem with 5.8 m multispectral LISS IV data, discerns tree crowns and clusters at a detailed scale and hence semi-automated approach is attempted to classify TOF from a pair of image from relatively crop and cloud free season. Object based image analysis(OBIA) approach as implemented in commercial suite of e-Cognition (Ver 8.9) consists of segmentation at user defined scale followed by application of wide range of spectral, textural and object geometry based parameters for classification. Software offers innovative blend of raster and vector features that can be juxtaposed flexibly, across scales horizontally or vertically. Segmentation was carried out at multiple scales to discern first the major land covers, such as forest, water, agriculture followed by that at a finer

  14. Spatial representativeness of ground-based solar radiation measurements estimated from high-resolution Meteosat data

    NASA Astrophysics Data System (ADS)

    Zyta Hakuba, Maria; Folini, Doris; Sanchez-Lorenzo, Arturo; Wild, Martin

    2014-05-01

    The validation of gridded surface solar radiation (SSR) data often relies on the comparison with ground-based in-situ measurements. This poses the question on how representative a point measurement is for a larger-scale surrounding. We use the high-resolution (0.03° ) SIS MVIRI data from the Satellite Application Facility on Climate Monitoring (CM SAF) to study the spatial sub-grid variability in all-sky surface solar radiation (SSR) over Europe, Africa, and parts of South America as covered by the Meteosat disk. This is done for the CERES EBAF 1° standard grid and two equal-angle grids of 0.25° and 3° resolution. Furthermore, we quantify the spatial representativeness of numerous surface sites from the BSRN and the GEBA for their site-centered larger surroundings varying in size from 0.25° to 3°, as well as with respect to the given standard grids. These analyses are done on a climatological annual and monthly mean basis over the period 2001-2005. The annual mean sub-grid variability (mean absolute deviation) in the 1° standard grid over European land is on average 1.6% (2.4 Wm¯²), with a maximum of up to 10% in Northern Spain (Hakuba et al. 2013). As expected, highest sub-grid variability is found in mountainous and coastal regions. The annual mean representation error of point values at 143 surface sites in Europe with respect to their 1° surrounding and the 1° standard grid is on average 2% (3 Wm¯² ). For larger surroundings of 3°, the representation error increases to 3% (4.8 Wm¯²), which is of similar order as the measurement accuracy of in-situ observations. Most of the sites can thus be considered as representative for their larger surroundings of up to 3°, which holds also true for the majority of BSRN sites located in Africa and South America. This representation error can be reduced if site-specific correction factors are applied or when multiple sites are available in the same grid cell, i.e., three more sites reduce the error by 50

  15. Quantifying the influences of spectral resolution on uncertainty in leaf trait estimates through a Bayesian approach to RTM inversion

    DOE PAGES

    Shiklomanov, Alexey N.; Dietze, Michael C.; Viskari, Toni; ...

    2016-06-09

    examine the influence of spectral resolution on parameter uncertainty, we simulated leaf reflectance as observed by ten common remote sensing platforms with varying spectral configurations and performed a Bayesian inversion on the resulting spectra. We found that full-range hyperspectral platforms were able to retrieve all parameters accurately and precisely, while the parameter estimates of multispectral platforms were much less precise and prone to bias at high and low values. We also observed that variations in the width and location of spectral bands influenced the shape of the covariance structure of parameter estimates. Lastly, our Bayesian spectral inversion provides a powerful and versatile framework for future RTM development and single- and multi-instrumental remote sensing of vegetation.« less

  16. Quantifying the influences of spectral resolution on uncertainty in leaf trait estimates through a Bayesian approach to RTM inversion

    SciTech Connect

    Shiklomanov, Alexey N.; Dietze, Michael C.; Viskari, Toni; Townsend, Philip A.; Serbin, Shawn P.

    2016-06-09

    were less accurate (CVEWT = 53.2%, CVLMA = 63.3%). To examine the influence of spectral resolution on parameter uncertainty, we simulated leaf reflectance as observed by ten common remote sensing platforms with varying spectral configurations and performed a Bayesian inversion on the resulting spectra. We found that full-range hyperspectral platforms were able to retrieve all parameters accurately and precisely, while the parameter estimates of multispectral platforms were much less precise and prone to bias at high and low values. We also observed that variations in the width and location of spectral bands influenced the shape of the covariance structure of parameter estimates. Lastly, our Bayesian spectral inversion provides a powerful and versatile framework for future RTM development and single- and multi-instrumental remote sensing of vegetation.

  17. High resolution simulations and glider observations in the eastern Alboran Sea (Mediterranean Sea): implications for vertical velocity estimates

    NASA Astrophysics Data System (ADS)

    Mason, Evan; Pascual, Ananda; McWilliams, James C.

    2013-04-01

    The transition region between the Alboran Sea and the Algerian sub-basin to the east is characterised by strong fronts and mesoscale anticyclonic eddies, and has correspondingly raised levels of eddy kinetic energy. The transient Almería-Orán front separates Atlantic Water (AW) flowing into the Mediterranean Sea, and recirculating Mediterranean Water (MW) that intrudes southwestward along the Spanish coast. Quasi-geostrophic vertical motions estimated from a combination of altimetry and glider observations by Ruiz et al. (2009) are of the order of ±1 m day-1, although higher velocities (up to 20-25 m day-1) can be assumed for smaller scale structures embedded within the front, as revealed by chlorophyll data and pointed out by Tintoré et al. (1991). In order to further investigate the vertical velocity spectrum we present results from a high resolution nested modelling study that focuses on the Almería-Orán front. The model is the primitive equation Regional Ocean Modeling System (ROMS). We identify the conditions under which the front forms using a 5 km resolution Mediterranean climatological solution that is run for 15 years. A series of one-way nested simulations then lead to a sub-km solution that permits a high resolution characterisation of the 3D structure of the front. These are then compared with glider observations collected during July 2009. Further, this work will support a high-resolution multi-platform experiment to sample the Almería-Orán front that is to take place in Spring 2014 as part of the European project FP7 PERSEUS.

  18. Estimation of Surface Air Temperature from MODIS 1km Resolution Land Surface Temperature Over Northern China

    NASA Technical Reports Server (NTRS)

    Shen, Suhung; Leptoukh, Gregory G.; Gerasimov, Irina

    2010-01-01

    Surface air temperature is a critical variable to describe the energy and water cycle of the Earth-atmosphere system and is a key input element for hydrology and land surface models. It is a very important variable in agricultural applications and climate change studies. This is a preliminary study to examine statistical relationships between ground meteorological station measured surface daily maximum/minimum air temperature and satellite remotely sensed land surface temperature from MODIS over the dry and semiarid regions of northern China. Studies were conducted for both MODIS-Terra and MODIS-Aqua by using year 2009 data. Results indicate that the relationships between surface air temperature and remotely sensed land surface temperature are statistically significant. The relationships between the maximum air temperature and daytime land surface temperature depends significantly on land surface types and vegetation index, but the minimum air temperature and nighttime land surface temperature has little dependence on the surface conditions. Based on linear regression relationship between surface air temperature and MODIS land surface temperature, surface maximum and minimum air temperatures are estimated from 1km MODIS land surface temperature under clear sky conditions. The statistical errors (sigma) of the estimated daily maximum (minimum) air temperature is about 3.8 C(3.7 C).

  19. Size estimates for intervening CIV absorbers from high-resolution spectroscopy of APM 0827+5255

    NASA Astrophysics Data System (ADS)

    Tzanavaris, Panayiotis; Carswell, Robert F.

    2003-04-01

    A new analysis of Keck/HIRES observations of the broad absorption line quasi-stellar object (QSO) APM 0827+5255 indicates that a number of intervening CIV absorbers give rise to absorption lines for which the observed optical depths for the 1548, 1550 Å doublet components are not in the expected 2:1 ratio. To compensate for the effect, a local adjustment of the zero-level is required. We model this effect as coverage of one line of sight to this gravitationally lensed QSO and perform a set of simulations to select a sample of lines for which our model provides an explanation for the effect. We use lines in this sample to obtain estimates for minimum CIV absorber sizes from total coverage and the separations of the lines of sight for a range of lens redshifts, zl, and two cosmologies. We also obtain best estimates for overall sizes from a statistical `hit and miss' approach. For zl= 0.7 our results set a lower limit to sizes of CIV absorbers of ~0.3 h-172 kpc (~0.5 h-172 kpc) for ΩM= 1, ΩΛ= 0 (ΩM= 0.3, ΩΛ= 0.7), in agreement with other results from similar work but are limited by sample size and the uncertainty in zl. Our method can be used to detect lensed QSOs and to probe absorber sizes when separate spectra cannot be obtained for each line of sight.

  20. The effects of 30 mT electromagnetic fields on hippocampus cells of rats

    PubMed Central

    Teimori, Farzaneh; Khaki, Amir A.; Rajabzadeh, Asghar; Roshangar, Leila

    2016-01-01

    Background: Despite the use of electromagnetic waves in the treatment of some acute and chronic diseases, application of these waves in everyday life has created several problems for humans, especially the nerve system. In this study, the effects of 30mT electromagnetic fields (EMFs) on the hippocampus is investigated. Methods: Twenty-four 5-month Wistar rats weighing 150–200 g were divided into two groups. The experimental group rats were under the influence of an EMF at an intensity of 3 mT for approximately 4 hours a day (from 8 AM to 12 PM) during 10 weeks. After the hippocampus was removed, thin slides were prepared for transmission electron microscope (TEM) to study the ultrastructural tissue. Cell death detection POD kits were used to determine the apoptosis rate. Results: The results of the TEM showed that, in the hippocampus of the experimental group, in comparison to the control group, there was a substantial shift; even intracellular organelles such as the mitochondria were morphologically abnormal and uncertain. The number of apoptotic cells in the exposed group compared to the control group showed significant changes. Conclusions: Similar to numerous studies that have reported the effects of EMFs on nerves system, it was also confirmed in this lecture. Hence, the hippocampus which is important in regulating emotions, behavior, motivation, and memory functions, may be impaired by the negative impacts of EMFs. PMID:27453795

  1. Revised spectroscopic parameters of SH(+) from ALMA and IRAM 30m observations.

    PubMed

    Müller, Holger S P; Goicoechea, Javier R; Cernicharo, José; Agúndez, Marcelino; Pety, Jérôme; Cuadrado, Sara; Gerin, Maryvonne; Dumas, Gaëlle; Chapillon, Edwige

    2014-09-19

    Hydrides represent the first steps of interstellar chemistry. Sulfanylium (SH(+)), in particular, is a key tracer of energetic processes. We used ALMA and the IRAM 30 m telescope to search for the lowest frequency rotational lines of SH(+) toward the Orion Bar, the prototypical photo-dissociation region illuminated by a strong UV radiation field. On the basis of previous Herschel/HIFI observations of SH(+), we expected to detect emission of the two SH(+) hyperfine structure (HFS) components of the NJ = 10-01 fine structure (FS) component near 346 GHz. While we did not observe any lines at the frequencies predicted from laboratory data, we detected two emission lines, each ~15 MHz above the SH(+) predictions and with relative intensities and HFS splitting expected for SH(+). The rest frequencies of the two newly detected lines are more compatible with the remainder of the SH(+) laboratory data than the single line measured in the laboratory near 346 GHz and previously attributed to SH(+). Therefore, we assign these new features to the two SH(+) HFS components of the NJ = 10-01 FS component and re-determine its spectroscopic parameters, which will be useful for future observations of SH(+), in particular if its lowest frequency FS components are studied. Our observations demonstrate the suitability of these lines for SH(+) searches at frequencies easily accessible from the ground.

  2. A new remote sensing procedure for the estimation of crop water requirements

    NASA Astrophysics Data System (ADS)

    Spiliotopoulos, M.; Loukas, A.; Mylopoulos, N.

    2015-06-01

    The objective of this work is the development of a new approach for the estimation of water requirements for the most important crops located at Karla Watershed, central Greece. Satellite-based energy balance for mapping evapotranspiration with internalized calibration (METRIC) was used as a basis for the derivation of actual evapotranspiration (ET) and crop coefficient (ETrF) values from Landsat ETM+ imagery. MODIS imagery has been also used, and a spatial downscaling procedure is followed between the two sensors for the derivation of a new NDVI product with a spatial resolution of 30 m x 30 m. GER 1500 spectro-radiometric measurements are additionally conducted during 2012 growing season. Cotton, alfalfa, corn and sugar beets fields are utilized, based on land use maps derived from previous Landsat 7 ETM+ images. A filtering process is then applied to derive NDVI values after acquiring Landsat ETM+ based reflectance values from the GER 1500 device. ETrF vs NDVI relationships are produced and then applied to the previous satellite based downscaled product in order to finally derive a 30 m x 30 m daily ETrF map for the study area. CropWat model (FAO) is then applied, taking as an input the new crop coefficient values with a spatial resolution of 30 m x 30 m available for every crop. CropWat finally returns daily crop water requirements (mm) for every crop and the results are analyzed and discussed.

  3. High Resolution, Consistent Online Estimation of Potential Flood Damage in The Netherlands

    NASA Astrophysics Data System (ADS)

    Hoes, O.; Hut, R.; van Leeuwen, E.

    2014-12-01

    In the current age where water authorities no longer blindly design and maintain all infrastructure just to meet a certain standardized return period, accurate estimation of potential flood damage is important in decision making with regards to flood prevention measures. We identify three issues with current methods of estimating flood damages. Firstly, common practice is to assume that for a given land use type, damage is mainly dependent on inundation depth, and sometimes flow velocity. We recognize that depending on the type of land use inundation depth, velocity, flood duration, season, detour time and recovery time influences the amount of damage significantly. Secondly, setting stage-damage curves is usually left to an end user and can thus vary between different water authorities within a single country. What was needed at a national level is a common way of calculating flood damages, so different prevention measures can be fairly compared. Finally, most flood models use relatively large grid cells, usually in the order of 25 m2 or coarser. Especially in urban areas this leads to obvious errors: different land uses (shops, housing, park, are all classified as "urban" and treated equally. To tackle these issues we developed a web-based model which can be accessed via www.waterschadeschatter.nl (water schade schatter is Dutch for water damage estimator). It includes all necessary data sources to calculate the damage of any potential flood in the Netherlands. It uses different damage functions for different land use types, which the user can, but need not change. It runs on 0.25m2 grid cells. Both the datasets required and the amount of calculation needed is more than a desktop computer can handle. In order to start a calculation a user needs to upload the relevant flood information to the website. The calculation is divided over several multicore servers, after which the user will receive an email with a link to the results of his calculations. Our

  4. Bias Adjustment of high spatial/temporal resolution Satellite Precipitation Estimation relying on Gauge-Based precipitation over China

    NASA Astrophysics Data System (ADS)

    Yu, J.; Pan, Y.; Shen, Y.

    2010-12-01

    Satellite precipitation data has been widely used in the forecasting and research of weather and climate because of its high spatial/temporal resolution, especially in the area of limited access to ground-based measurements. The distribution of gauge stations in China is very uniform with most gauge stations located in Eastern China and few gauge stations located in Western China. So the using of satellite precipitation data in China is very important. Although the satellite precipitation data has a good spatial construction, its estimation value is less accurate and has distinct systematic bias comparing to gauge-based one. The bias of satellite precipitation data should be adjusted before using it. In this paper, the CMORPH (Climate Prediction Center Morphing Technique) 30-min precipitation products is chosen to represent the large-scale precipitation of China and be adjusted based on hourly rain gauge analysis over China by interpolating from more than 10000 stations collected and quality controlled by the National Meteorological Information Center of the China Meteorological by using a probability density function (PDF) matching method (Wang and Xie, 2005). After bias-adjustment by PDF matching, we get a less systematic bias and high-resolution satellite precipitation product, which is hourly precipitation on a 0.1°latitude/longitude grid over China. Adjusted values are more close to the gauge observations, and the probability density function of corrected precipitation products is the same as that of the gauge-based precipitation. In Western China, the quantity value of corrected precipitation estimates is obviously increased comparing to the original estimate value. On the other hand, the spatial construction is still maintenance of satellite products.

  5. High resolution X-Band radar rainfall estimates for a Mediterranean to hyper-arid transition area

    NASA Astrophysics Data System (ADS)

    Marra, Francesco; Lokshin, Anton; Notarpietro, Riccardo; Gabella, Marco; Branca, Marco; Bonfil, David; Morin, Efrat

    2015-04-01

    Weather radars provide rainfall estimates with high spatial and temporal resolutions over wide areas. X-Band weather radars are of relatively low-cost and easy to be handled and maintained, moreover they offer extremely high spatial and temporal resolutions and are therefore object of particular interest. Main drawback of these instruments lies on the quantitative accuracy, that can be significantly affected by atmospheric attenuation. Distributed rainfall information is a key issue when hydrological applications are needed for small space-time scale phenomena such as flash floods and debris flows. Moreover, such detailed measurements represent a great benefit for agricultural management of areas characterized by substantial rainfall variability. Two single polarization, single elevation, non-Doppler X-Band weather radars are operational since Oct-2012 in the northern Negev (Israel). Mean annual precipitation over the area drops dramatically from 500 mm/yr at the Mediterranean coast to less than 50 mm/yr at the hyper-arid region near the Dead Sea in less than a 100 km distance. The dryer region close to the Dead Sea is prone to flash floods that often cause casualties and severe damage while the western Mediterranean region is extensively used for agricultural purposes. Measures from a C-Band weather radar located 40-120 km away and from a sparse raingauge network (density ~1gauge/450km2) are also available. C-Band rainfall estimates are corrected using combined physically-based and empirical adjustment of data. The aim of this study is to assess the quantitative accuracy of X-Band rainfall estimates with respect to the combined use of in situ measurements and C-Band observations. Results from a set of storms occurred during the first years of measurements are discussed paying particular attention to: (i) wet radome attenuation, (ii) range dependent degradation including attenuation along the path and (iii) systematic effects related to the Mediterranean to hyper

  6. Estimating gross primary productivity (GPP) of forests across southern England at high spatial and temporal resolution using the FLIGHT model

    NASA Astrophysics Data System (ADS)

    Pankaew, Prasan; Milton, Edward; Dawson, Terry; Dash, Jadu

    2013-04-01

    Forests and woodlands play an important role in CO2 flux and in the storage of carbon, therefore it is important to be able to estimate gross primary productivity (GPP) and its change over time. The MODIS GPP product (MOD17) provides near-global GPP, but at relatively coarse spatial resolution (1km pixel size) and only every eight days. In order to study the dynamics of GPP over shorter time periods and over smaller areas it is necessary to make ground measurements or use a plant canopy model. The most reliable ground-based GPP data are those from the FLUXNET network, which comprises over 500 sites worldwide, each of which measures GPP using the eddy covariance method. Each FLUXNET measurement corresponds to GPP from an area around the sampling tower, the size and shape of which varies with weather conditions, notably wind speed and direction. The FLIGHT forest light simulation model (North, 1996) is a Monte Carlo based model to estimate the GPP from forest canopies, which does not take into account the spatial complexity of the site or the wind conditions at the time. Forests in southern England are small and embedded in a matrix of other land cover types (agriculture, urban etc.), so GPP estimated from FLIGHT needs to be adjusted to match that measured from a FLUXNET tower. The aim of this paper is to develop and test a method to adjust FLIGHT GPP so that it matches FLUXNET GPP. The advantage of this is that GPP can then be estimated over many other forests which do not possess FLUXNET sites. The study was based on data from two mixed broadleaf forests in southern England (Wytham Woods and Alice Holt forest), both of which have FLUXNET sites located within them. The FLUXNET meteorological data were prepared for use in the FLIGHT model by converting broadband irradiance to photosynthetically active radiance (PAR) and estimating diffuse PAR, using methods developed in previous work by the authors. The standard FLIGHT model tended to overestimate GPP in the winter

  7. Cerebral Blood Flow Estimation Using Classification Techniques On A Sequence Of Low Resolution Tomographic Evolutive Images

    NASA Astrophysics Data System (ADS)

    Chan, Marie; Aguilar-Martin, Joseph; Boulanouar, Kader; Celsis, Pierre; Marc-Vergnes, Jean P.

    1989-05-01

    In order to improve the performance of the instrumental variable method (IVM) in calculating regional cerebral blood flow (rCBF) using Single Photon Emission Computed Tomography (SPELT), and inert diffusible tracer such as 133Xe, we use Learning Algorithms for Multivariate Data Analysis (LAMDA) to classify the voxels of the images of local concentrations in the brain. The LAMDA method correctly distinguished between extra and intra-cerebral voxels. However the topography of the intra-cerebral classes did not match the Regions Of Interest (ROI) defined on an anatomical basis. Provided that all the intra-cerebral classes contaminated by bone and air passage artefact were rejected, the results given by the NM are in good agreement with those derived by the bolus distribution principle. We thus conclude that LAMDA methods can improve the reliability of images of CBF estimates.

  8. Preparation for GPM: Development of a New Near Real-time High Resolution Multi-sensor Precipitation Estimation Product Based on Analyzing the Existing Precipitation Estimation Techniques

    NASA Astrophysics Data System (ADS)

    Behrangi, A.; Sorooshian, S.; Hsu, K.; Bellerby, T. J.; Huffman, G. J.; Lambrigtsen, B.

    2010-12-01

    By analyzing the existing precipitation estimation techniques, a new near real-time multi-platform multi-sensor satellite precipitation estimation algorithm is developed which incorporates cloud classification techniques to effectively adjust microwave (MW) precipitation intensities as advected forward/backward in time. The technique which will significantly benefit from the future Global Precipitation Measurement (GPM) mission consists of three main steps: The first step uses successive IR images to calculate cloud motion streamlines from a 2D cloud tracking algorithm, explicitly incorporating the effect of cloud motion, growth, deformation and dispersal. The second step classifies cloudy pixels into a number of predefined clusters using several infrared-extracted cloud features representing radiative, textural and dynamic properties of clouds. The algorithm is also capable to readily incorporate multi-spectral information to improve the cloud classification system. By calculating the precipitation features in each class, MW precipitation intensity is adjusted as advected between two consecutive microwave overpasses, both forward-only and forward- backward. The technique was developed and tested at 0.08-degree latitude/longitude resolution every 30 minutes and evaluated over the conterminous United States. The performance of the algorithm compared favorably with several existing products which will be discussed.

  9. Using high-resolution satellite aerosol optical depth to estimate daily PM2.5 geographical distribution in Mexico City

    PubMed Central

    Just, Allan C.; Wright, Robert O.; Schwartz, Joel; Coull, Brent A.; Baccarelli, Andrea A.; Tellez-Rojo, Martha María; Moody, Emily; Wang, Yujie; Lyapustin, Alexei; Kloog, Itai

    2015-01-01

    Recent advances in estimating fine particle (PM2.5) ambient concentrations use daily satellite measurements of aerosol optical depth (AOD) for spatially and temporally resolved exposure estimates. Mexico City is a dense megacity that differs from other previously modeled regions in several ways: it has bright land surfaces, a distinctive climatological cycle, and an elevated semi-enclosed air basin with a unique planetary boundary layer dynamic. We extend our previous satellite methodology to the Mexico City area, a region with higher PM2.5 than most US and European urban areas. Using a novel 1 km resolution AOD product from the MODIS instrument, we constructed daily predictions across the greater Mexico City area for 2004–2014. We calibrated the association of AOD to PM2.5 daily using municipal ground monitors, land use, and meteorological features. Predictions used spatial and temporal smoothing to estimate AOD when satellite data were missing. Our model performed well, resulting in an out-of-sample cross validation R2 of 0.724. Cross-validated root mean squared prediction error (RMSPE) of the model was 5.55 μg/m3. This novel model reconstructs long- and short-term spatially resolved exposure to PM2.5 for epidemiological studies in Mexico City. PMID:26061488

  10. Using High-Resolution Satellite Aerosol Optical Depth To Estimate Daily PM2.5 Geographical Distribution in Mexico City.

    PubMed

    Just, Allan C; Wright, Robert O; Schwartz, Joel; Coull, Brent A; Baccarelli, Andrea A; Tellez-Rojo, Martha María; Moody, Emily; Wang, Yujie; Lyapustin, Alexei; Kloog, Itai

    2015-07-21

    Recent advances in estimating fine particle (PM2.5) ambient concentrations use daily satellite measurements of aerosol optical depth (AOD) for spatially and temporally resolved exposure estimates. Mexico City is a dense megacity that differs from other previously modeled regions in several ways: it has bright land surfaces, a distinctive climatological cycle, and an elevated semi-enclosed air basin with a unique planetary boundary layer dynamic. We extend our previous satellite methodology to the Mexico City area, a region with higher PM2.5 than most U.S. and European urban areas. Using a novel 1 km resolution AOD product from the MODIS instrument, we constructed daily predictions across the greater Mexico City area for 2004-2014. We calibrated the association of AOD to PM2.5 daily using municipal ground monitors, land use, and meteorological features. Predictions used spatial and temporal smoothing to estimate AOD when satellite data were missing. Our model performed well, resulting in an out-of-sample cross-validation R(2) of 0.724. Cross-validated root-mean-squared prediction error (RMSPE) of the model was 5.55 μg/m(3). This novel model reconstructs long- and short-term spatially resolved exposure to PM2.5 for epidemiological studies in Mexico City.

  11. The Role of Orograph and Parallax Corrections on High Resolution Geostationary Satellite Rainfall Estimates for Flash Flood Applications

    NASA Technical Reports Server (NTRS)

    Vicente, Gilberto A.; Davenport, Clay; Scofield, Rod

    1999-01-01

    The current generation of geosynchronous satellites exhibits considerably improved capabilities in the area of resolution, gridding accuracy, and sampling frequency as compared to their predecessors. These improvements have made it possible to accurately observe the life cycle of small scale, short-live phenomenon like rapidly developing thunderstorms, at a very high spatial and temporal resolutions. While the gain in the improved resolution is not significant for synoptic scale cloud systems, it plays a major role on the computation of precipitation values for mesoscale and stonn scale systems. Two of the important factor on the accurate precision of precipitation from satellite imagery are the position of the cloud tops as viewed by the satellite and the influence of orographic effects on the distribution of precipitation. The first problem has to do with the fact that the accurate estimation of precipitation from data collected by a satellite in geosynchronous orbit requires the knowledge of the exact position of the cloud tops with respect to the ground below. This is not a problem when a cloud is located directly below the satellite; at large viewing angles the geographic coordinates on satellite images are dependent on cloud heights and distance from the sub-satellite point. The latitude and longitude coordinates for high convective cloud tops are displaced away from the sub-satellite point and may be shifted by as much as 20 Km from the sea level coordinates. The second problem has to do with the variations in rainfall distribution with elevation. Ground observations have shown that precipitation amounts tend to increase with height and that the slope of the hill or mountain that is facing the prevailing wind normally receives greater rainfall then do the lee slopes. The purpose of the study is to show the recent developments at the Office of Research and Applications (ORA) at the National Oceanic and Atmospheric Administration (NOAA/NESDIS) in Camp Springs

  12. Estimating photosynthesis with high resolution field spectroscopy in a Mediterranean grassland under different nutrient availability

    NASA Astrophysics Data System (ADS)

    Perez-Priego, O.; Guan, J.; Fava, F.; Rossini, M.; Wutzler, T.; Moreno, G.; Carrara, A.; Kolle, O.; Schrumpf, M.; Reichstein, M.; Migliavacca, M.

    2014-12-01

    Recent studies have shown how human induced N:P imbalances are affecting essential processes (e.g. photosynthesis, plant growth rate) that lead to important changes in ecosystem structure and function. In this regard, the accuracy of the approaches based on remotely-sensed data for monitoring and modeling gross primary production (GPP) relies on the ability of vegetation indices (VIs) to track the dynamics of vegetation physiological and biophysical properties/variables. Promising results have been recently obtained when Chlorophyll-sensitive VIs and Chlorophyll fluorescence are combined with structural indices in the framework of the Monteith's light use efficiency (LUE) model. However, further ground-based experiments are required to validate LUE model performances, and their capability to be generalized under different nutrient availability conditions. In this study, the overall objective was to investigate the sensitivity of VIs to track short- and long-term GPP variations in a Mediterranean grassland under different N and P fertilization treatments. Spectral VIs were acquired manually using high resolution spectrometers (HR4000, OceanOptics, USA) along a phenological cycle. The VIs examined included photochemical reflectance index (PRI), MERIS terrestrial-chlorophyll index (MTCI) and normalized difference vegetation index (NDVI). Solar-induced chlorophyll fluorescence calculated at the oxygen absorption band O2-A (F760) using spectral fitting methods was also used. Simultaneously, measurements of GPP and environmental variables were conducted using a transient-state canopy chamber. Overall, GPP, F760 and VIs showed a clear seasonal time-trend in all treatments, which was driven by the phenological development of the grassland. Results showed significant differences (p<0.05) in midday GPP values between N and without N addition plots, in particular at the peak of the growing season during the flowering stage and at the end of the season during senescence. While

  13. Ecosystem services - from assessements of estimations to quantitative, validated, high-resolution, continental-scale mapping via airborne LIDAR

    NASA Astrophysics Data System (ADS)

    Zlinszky, András; Pfeifer, Norbert

    2016-04-01

    service potential" which is the ability of the local ecosystem to deliver various functions (water retention, carbon storage etc.), but can't quantify how much of these are actually used by humans or what the estimated monetary value is. Due to its ability to measure both terrain relief and vegetation structure in high resolution, airborne LIDAR supports direct quantification of the properties of an ecosystem that lead to it delivering a given service (such as biomass, water retention, micro-climate regulation or habitat diversity). In addition, its high resolution allows direct calibration with field measurements: routine harvesting-based ecological measurements, local biodiversity indicator surveys or microclimate recordings all take place at the human scale and can be directly linked to the local value of LIDAR-based indicators at meter resolution. Therefore, if some field measurements with standard ecological methods are performed on site, the accuracy of LIDAR-based ecosystem service indicators can be rigorously validated. With this conceptual and technical approach high resolution ecosystem service assessments can be made with well established credibility. These would consolidate the concept of ecosystem services and support both scientific research and evidence-based environmental policy at local and - as data coverage is continually increasing - continental scale.

  14. A DUAL-BAND MILLIMETER-WAVE KINETIC INDUCTANCE CAMERA FOR THE IRAM 30 m TELESCOPE

    SciTech Connect

    Monfardini, A.; Benoit, A.; Bideaud, A.; Swenson, L.; Cruciani, A.; Camus, P.; Hoffmann, C.; Desert, F. X.; Doyle, S.; Ade, P.; Mauskopf, P.; Tucker, C.; Roesch, M.; Leclercq, S.; Schuster, K. F.; Endo, A.; Baryshev, A.; Baselmans, J. J. A.; Ferrari, L.; Yates, S. J. C

    2011-06-01

    The Neel IRAM KIDs Array (NIKA) is a fully integrated measurement system based on kinetic inductance detectors (KIDs) currently being developed for millimeter wave astronomy. The instrument includes dual-band optics allowing simultaneous imaging at 150 GHz and 220 GHz. The imaging sensors consist of two spatially separated arrays of KIDs. The first array, mounted on the 150 GHz branch, is composed of 144 lumped-element KIDs. The second array (220 GHz) consists of 256 antenna-coupled KIDs. Each of the arrays is sensitive to a single polarization; the band splitting is achieved by using a grid polarizer. The optics and sensors are mounted in a custom dilution cryostat, with an operating temperature of {approx}70 mK. Electronic readout is realized using frequency multiplexing and a transmission line geometry consisting of a coaxial cable connected in series with the sensor array and a low-noise 4 K amplifier. The dual-band NIKA was successfully tested in 2010 October at the Institute for Millimetric Radio Astronomy (IRAM) 30 m telescope at Pico Veleta, Spain, performing in-line with laboratory predictions. An optical NEP was then calculated to be around 2 x 10{sup -16} W Hz{sup -1/2} (at 1 Hz) while under a background loading of approximately 4 pW pixel{sup -1}. This improvement in comparison with a preliminary run (2009) verifies that NIKA is approaching the target sensitivity for photon-noise limited ground-based detectors. Taking advantage of the larger arrays and increased sensitivity, a number of scientifically relevant faint and extended objects were then imaged including the Galactic Center SgrB2 (FIR1), the radio galaxy Cygnus A, and the NGC1068 Seyfert galaxy. These targets were all observed simultaneously in the 150 GHz and 220 GHz atmospheric windows.

  15. A Dual-band Millimeter-wave Kinetic Inductance Camera for the IRAM 30 m Telescope

    NASA Astrophysics Data System (ADS)

    Monfardini, A.; Benoit, A.; Bideaud, A.; Swenson, L.; Cruciani, A.; Camus, P.; Hoffmann, C.; Désert, F. X.; Doyle, S.; Ade, P.; Mauskopf, P.; Tucker, C.; Roesch, M.; Leclercq, S.; Schuster, K. F.; Endo, A.; Baryshev, A.; Baselmans, J. J. A.; Ferrari, L.; Yates, S. J. C.; Bourrion, O.; Macias-Perez, J.; Vescovi, C.; Calvo, M.; Giordano, C.

    2011-06-01

    The Néel IRAM KIDs Array (NIKA) is a fully integrated measurement system based on kinetic inductance detectors (KIDs) currently being developed for millimeter wave astronomy. The instrument includes dual-band optics allowing simultaneous imaging at 150 GHz and 220 GHz. The imaging sensors consist of two spatially separated arrays of KIDs. The first array, mounted on the 150 GHz branch, is composed of 144 lumped-element KIDs. The second array (220 GHz) consists of 256 antenna-coupled KIDs. Each of the arrays is sensitive to a single polarization; the band splitting is achieved by using a grid polarizer. The optics and sensors are mounted in a custom dilution cryostat, with an operating temperature of ~70 mK. Electronic readout is realized using frequency multiplexing and a transmission line geometry consisting of a coaxial cable connected in series with the sensor array and a low-noise 4 K amplifier. The dual-band NIKA was successfully tested in 2010 October at the Institute for Millimetric Radio Astronomy (IRAM) 30 m telescope at Pico Veleta, Spain, performing in-line with laboratory predictions. An optical NEP was then calculated to be around 2 × 10-16 W Hz-1/2 (at 1 Hz) while under a background loading of approximately 4 pW pixel-1. This improvement in comparison with a preliminary run (2009) verifies that NIKA is approaching the target sensitivity for photon-noise limited ground-based detectors. Taking advantage of the larger arrays and increased sensitivity, a number of scientifically relevant faint and extended objects were then imaged including the Galactic Center SgrB2 (FIR1), the radio galaxy Cygnus A, and the NGC1068 Seyfert galaxy. These targets were all observed simultaneously in the 150 GHz and 220 GHz atmospheric windows.

  16. SACRA - a method for the estimation of global high-resolution crop calendars from a satellite-sensed NDVI

    NASA Astrophysics Data System (ADS)

    Kotsuki, S.; Tanaka, K.

    2015-11-01

    To date, many studies have performed numerical estimations of biomass production and agricultural water demand to understand the present and future supply-demand relationship. A crop calendar (CC), which defines the date or month when farmers sow and harvest crops, is an essential input for the numerical estimations. This study aims to present a new global data set, the SAtellite-derived CRop calendar for Agricultural simulations (SACRA), and to discuss advantages and disadvantages compared to existing census-based and model-derived products. We estimate global CC at a spatial resolution of 5 arcmin using satellite-sensed normalized difference vegetation index (NDVI) data, which corresponds to vegetation vitality and senescence on the land surface. Using the time series of the NDVI averaged from three consecutive years (2004-2006), sowing/harvesting dates are estimated for six crops (temperate-wheat, snow-wheat, maize, rice, soybean and cotton). We assume time series of the NDVI represent the phenology of one dominant crop and estimate CCs of the dominant crop in each grid. The dominant crops are determined using harvested areas based on census-based data. The cultivation period of SACRA is identified from the time series of the NDVI; therefore, SACRA considers current effects of human decisions and natural disasters. The difference between the estimated sowing dates and other existing products is less than 2 months (< 62 days) in most of the areas. A major disadvantage of our method is that the mixture of several crops in a grid is not considered in SACRA. The assumption of one dominant crop in each grid is a major source of discrepancy in crop calendars between SACRA and other products. The disadvantages of our approach may be reduced with future improvements based on finer satellite sensors and crop-type classification studies to consider several dominant crops in each grid. The comparison of the CC also demonstrates that identification of wheat type (sowing in

  17. Estimating the spatial resolution of fNIRS sensors for BCI purposes

    NASA Astrophysics Data System (ADS)

    Almajidy, Rand Kasim; Kirch, Robert D.; Christ, Olaf; Hofmann, Ulrich G.

    2014-03-01

    Differential near infrared sensors recently sparked a growing interest as a promising measuring modality for brain computer interfacing. In our study we present the design and characterization of novel, differential functional NIRS sensors, intended to record hemodynamic changes of the human motor cortex in the hand-area during motor imagery tasks. We report on the spatial characterization of a portable, multi-channel NIRS system with one module consisting of two central light emitting diodes (LED) (770 nm and 850 nm) and four symmetric pairs of radially aligned photodiodes (PD) resembling a plus symbol. The other sensor module features four similar, differential light paths crossing in the center of a star. Characterization was performed on a concentric, double beaker phantom, featuring a PBS/intralipid/blood mixture (97/1/2%). In extension of previous work, the inner, oxygenated beaker was covered by neoprene sleeves with holes of various sizes, thus giving an estimate on the spatial limits of the NIRS sensor's measurement volume. The star shaped sensor module formed a diffuse focus of approximately 3 cm in diameter at 1.4 cm depth, whereas the plus shaped arrangement suggested a concentric ring of four separate regions of interest, overall larger than 6 cm. The systems measurement sensitivity could be improved by removing ambient light from the sensing photodiodes by optical filtering. Altogether, we conclude that both our novel fNIRS design as well as its electronics perform well in the double-layered oxygenation phantom and are thus suitable for in-vivo testing.

  18. Continuous Space Estimation: Increasing WiFi-Based Indoor Localization Resolution without Increasing the Site-Survey Effort †

    PubMed Central

    Hernández, Noelia; Ocaña, Manuel; Alonso, Jose M.; Kim, Euntai

    2017-01-01

    Although much research has taken place in WiFi indoor localization systems, their accuracy can still be improved. When designing this kind of system, fingerprint-based methods are a common choice. The problem with fingerprint-based methods comes with the need of site surveying the environment, which is effort consuming. In this work, we propose an approach, based on support vector regression, to estimate the received signal strength at non-site-surveyed positions of the environment. Experiments, performed in a real environment, show that the proposed method could be used to improve the resolution of fingerprint-based indoor WiFi localization systems without increasing the site survey effort. PMID:28098773

  19. Continuous Space Estimation: Increasing WiFi-Based Indoor Localization Resolution without Increasing the Site-Survey Effort.

    PubMed

    Hernández, Noelia; Ocaña, Manuel; Alonso, Jose M; Kim, Euntai

    2017-01-13

    Although much research has taken place in WiFi indoor localization systems, their accuracy can still be improved. When designing this kind of system, fingerprint-based methods are a common choice. The problem with fingerprint-based methods comes with the need of site surveying the environment, which is effort consuming. In this work, we propose an approach, based on support vector regression, to estimate the received signal strength at non-site-surveyed positions of the environment. Experiments, performed in a real environment, show that the proposed method could be used to improve the resolution of fingerprint-based indoor WiFi localization systems without increasing the site survey effort.

  20. Using a hybrid Monte Carlo/Genetic Algorithm Slip Estimator to produce high resolution models of paleoearthquakes from geodetic data

    NASA Astrophysics Data System (ADS)

    Lindsay, A.; McCloskey, J.; Nalbant, S. S.; Simao, N.; Murphy, S.; NicBhloscaidh, M.; Steacy, S.

    2013-12-01

    Identifying fault sections where slip deficits have accumulated may provide a means for understanding sequences of large megathrust earthquakes. Stress accumulated during the interseismic period on locked sections of an active fault is stored as potential slip. Where this potential slip remains unreleased during earthquakes, a slip deficit can be said to have accrued. Analysis of the spatial distribution of slip during antecedent events along the fault will show where the locked plate has spent its stored slip and indicate where the potential for large events remains. The location of recent earthquakes and their distribution of slip can be estimated instrumentally. To develop the idea of long-term slip-deficit modelling it is necessary to constrain the size and distribution of slip for pre-instrumental events dating back hundreds of years covering more than one ';seismic cycle'. This requires the exploitation of proxy sources of data. Coral microatolls, growing in the intertidal zone of the outer island arc of the Sunda trench, present the possibility of producing high resolution reconstructions of slip for a number of pre-instrumental earthquakes. Their growth is influenced by tectonic flexing of the continental plate beneath them allows them to act as long term geodetic recorders. However, the sparse distribution of data available using coral geodesy results in a under determined problem with non-unique solutions. Instead of producing one definite model satisfying the observed corals displacements, a Monte Carlo Slip Estimator based on a Genetic Algorithm (MCSE-GA) accelerating the rate of convergence is used to identify a suite of models consistent with the data. Successive iterations of the MCSE-GA sample different displacements at each coral location, from within the spread of associated uncertainties, producing a catalog of models from the full range of possibilities. The suite of best slip distributions are weighted according to their fitness and stacked to

  1. Developing an Ice Volume Estimate of Jarvis Glacier, Alaska, using Ground-Penetrating Radar and High Resolution Satellite Imagery

    NASA Astrophysics Data System (ADS)

    Wu, N. L.; Campbell, S. W.; Douglas, T. A.; Osterberg, E. C.

    2013-12-01

    Jarvis Glacier is an important water source for Fort Greely and Delta Junction, Alaska. Yet with warming summer temperatures caused by climate change, the glacier is melting rapidly. Growing concern of a dwindling water supply has caused significant research efforts towards determining future water resources from spring melt and glacier runoff which feeds the community on a yearly basis. The main objective of this project was to determine the total volume of the Jarvis Glacier. In April 2012, a centerline profile of the Jarvis Glacier and 15 km of 100 MHz ground-penetrating radar (GPR) profiles were collected in cross sections to provide ice depth measurements. These depth measurements were combined with an interpreted glacier boundary (depth = 0 m) from recently collected high resolution WorldView satellite imagery to estimate total ice volume. Ice volume was calculated at 0.62 km3 over a surface area of 8.82 km2. However, it is likely that more glacier-ice exists within Jarvis Glacier watershed considering the value calculated with GPR profiles accounts for only the glacier ice within the valley and not for the valley side wall ice. The GLIMS glacier area database suggests that the valley accounts for approximately 50% of the total ice covered watershed. Hence, we are currently working to improve total ice volume estimates which incorporate the surrounding valley walls. Results from this project will be used in conjunction with climate change estimates and hydrological properties downstream of the glacier to estimate future water resources available to Fort Greely and Delta Junction.

  2. Analysis of decade-long time series of GPS-based polar motion estimates at 15-min temporal resolution

    NASA Astrophysics Data System (ADS)

    Sibois, Aurore E.; Desai, Shailen D.; Bertiger, Willy; Haines, Bruce J.

    2017-02-01

    We present results from the generation of 10-year-long continuous time series of the Earth's polar motion at 15-min temporal resolution using Global Positioning System ground data. From our results, we infer an overall noise level in our high-rate polar motion time series of 60 μas (RMS). However, a spectral decomposition of our estimates indicates a noise floor of 4 μas at periods shorter than 2 days, which enables recovery of diurnal and semidiurnal tidally induced polar motion. We deliberately place no constraints on retrograde diurnal polar motion despite its inherent ambiguity with long-period nutation. With this approach, we are able to resolve damped manifestations of the effects of the diurnal ocean tides on retrograde polar motion. As such, our approach is at least capable of discriminating between a historical background nutation model that excludes the effects of the diurnal ocean tides and modern models that include those effects. To assess the quality of our polar motion solution outside of the retrograde diurnal frequency band, we focus on its capability to recover tidally driven and non-tidal variations manifesting at the ultra-rapid (intra-daily) and rapid (characterized by periods ranging from 2 to 20 days) periods. We find that our best estimates of diurnal and semidiurnal tidally induced polar motion result from an approach that adopts, at the observation level, a reasonable background model of these effects. We also demonstrate that our high-rate polar motion estimates yield similar results to daily-resolved polar motion estimates, and therefore do not compromise the ability to resolve polar motion at periods of 2-20 days.

  3. High Resolution/High Fidelity Seismic Imaging and Parameter Estimation for Geological Structure and Material Characterization

    SciTech Connect

    Ru-Shan Wu, Xiao-Bi Xie, Thorne Lay

    2005-06-06

    In this project, we develop new theories and methods for multi-domain one-way wave-equation based propagators, and apply these techniques to seismic modeling, seismic imaging, seismic illumination and model parameter estimation in 3D complex environments. The major progress of this project includes: (1) The development of the dual-domain wave propagators. We continue to improve the one-way wave-equation based propagators. Our target is making propagators capable of handling more realistic velocity models. A wide-angle propagator for transversely isotropic media with vertically symmetric axis (VTI) has been developed for P-wave modeling and imaging. The resulting propagator is accurate for large velocity perturbations and wide propagation angles. The thin-slab propagator for one-way elastic-wave propagation is further improved. With the introduction of complex velocities, the quality factors Qp and Qs have been incorporated into the thin-slab propagator. The resulting viscoelastic thin-slab propagator can handle elastic-wave propagation in models with intrinsic attenuations. We apply this method to complex models for AVO modeling, random media characterization and frequency-dependent reflectivity simulation. (2) Exploring the Information in the Local Angle Domain. Traditionally, the local angle information can only be extracted using the ray-based method. We develop a wave-equation based technique to process the local angle domain information. The approach can avoid the singularity problem usually linked to the high-frequency asymptotic method. We successfully apply this technique to seismic illumination and the resulting method provides a practical tool for three-dimensional full-volume illumination analysis in complex structures. The directional illumination also provides information for angle-domain imaging corrections. (3) Elastic-Wave Imaging. We develop a multicomponent elastic migration method. The application of the multicomponent one-way elastic propagator

  4. Commutability of blur and affine warping in super-resolution with application to joint estimation of triple-coupled variables.

    PubMed

    Zhang, Xuesong; Jiang, Jing; Peng, Silong

    2012-04-01

    This paper proposes a new approach to the image blind super-resolution (BSR) problem in the case of affine interframe motion. Although the tasks of image registration, blur identification, and high-resolution (HR) image reconstruction are coupled in the imaging process, when dealing with nonisometric interframe motion or without the exact knowledge of the blurring process, classic SR techniques generally have to tackle them (maybe in some combinations) separately. The main difficulty is that state-of-the-art deconvolution methods cannot be straightforwardly generalized to cope with the space-variant motion. We prove that the operators of affine warping and blur commute with some additional transforms and derive an equivalent form of the BSR observation model. Using this equivalent form, we develop an iterative algorithm to jointly estimate the triple-coupled variables, i.e., the motion parameters, blur kernels, and HR image. Experiments on synthetic and real-life images illustrate the performance of the proposed technique in modeling the space-variant degradation process and restoring local textures.

  5. Absorbed dose estimates to structures of the brain and head using a high-resolution voxel-based head phantom.

    PubMed

    Evans, J F; Blue, T E; Gupta, N

    2001-05-01

    The purpose of this article is to demonstrate the viability of using a high-resolution 3-D head phantom in Monte Carlo N-Particle (MCNP) for boron neutron capture therapy (BNCT) structure dosimetry. This work describes a high-resolution voxel-based model of a human head and its use for calculating absorbed doses to the structures of the brain. The Zubal head phantom is a 3-D model of a human head that can be displayed and manipulated on a computer. Several changes were made to the original head phantom which now contains over 29 critical structures of the brain and head. The modified phantom is a 85 x 109 x 120 lattice of voxels, where each voxel is 2.2 x 2.2 x 1.4 mm3. This model was translated into MCNP lattice format. As a proof of principle study, two MCNP absorbed dose calculations were made (left and right lateral irradiations) using a uniformly distributed neutron disk source with an 1/E energy spectrum. Additionally, the results of these two calculations were combined to estimate the absorbed doses from a bilateral irradiation. Radiobiologically equivalent (RBE) doses were calculated for all structures and were normalized to 12.8 Gy-Eq. For a left lateral irradiation, the left motor cortex receives the limiting RBE dose. For a bilateral irradiation, the insula cortices receive the limiting dose. Among the nonencephalic structures, the parotid glands receive RBE doses that were within 15% of the limiting dose.

  6. High resolution reconstructions of Southwest Indian Ridge plate motions during the Neogene: Comparison to GPS estimates and implications for global plate motion estimates

    NASA Astrophysics Data System (ADS)

    DeMets, C.; Merkouriev, S.; Sauter, D.; Calais, E.

    2013-12-01

    Plate kinematic data from the slow-spreading Southwest Indian Ridge (SWIR) are the primary source of information about relative movements between Antarctica and Africa over geologic time and are critical for linking the movements of plates in the Atlantic and Indian Ocean basins. We describe the first high-resolution model of SWIR plate kinematics from the present to 20 Ma, consisting of rotations based on 21 magnetic reversals with ~1 million-year spacing. The new rotations, which are derived from 4822 identifications of magnetic reversals C1n to C6no and 6000 crossings of 21 fracture zones and transform faults, describe in detail the ultra-slow motions of the Nubia, Lwandle, and Somalia plates north of the SWIR relative to the Antarctic plate. A search for the Nubia-Lwandle-Antarctic triple junction with all data since C5n.2 (11.0 Ma) gives a best location at the Andrew Bain transform fault (~32E), in accord with previous work. Plate kinematic data from the SWIR east of the Andrew Bain fracture zone support the existence of the previously proposed Lwandle plate at high confidence level. The likely diffuse Lwandle-Somalia plate boundary north of the SWIR is however only loosely constrained to 45E-52E. After calibrating the new rotations for the biasing effects of finite-width magnetic polarity transition zones (i.e. outward displacement), the new rotations reveal that SWIR plate motion has remained steady from the present back to 7.5 Ma, but was modestly faster (~25%) from 19.6 Ma to 7.5 Ma. GPS estimates of present SWIR plate motions based on more than 100 continuous GPS sites on the Antarctic, Nubia, and Somalia plates are remarkably consistent with SWIR velocities determined with the new geological reconstructions. The superb agreement between the two independent plate motion estimates validates both sets of estimates and our calibration for outward displacement. Implications of the new estimates, including evidence for anomalously wide outward displacement

  7. Seasonal monitoring and estimation of regional aerosol distribution over Po valley, northern Italy, using a high-resolution MAIAC product

    NASA Astrophysics Data System (ADS)

    Arvani, Barbara; Pierce, R. Bradley; Lyapustin, Alexei I.; Wang, Yujie; Ghermandi, Grazia; Teggi, Sergio

    2016-09-01

    In this work, the new 1 km-resolved Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm is employed to characterize seasonal PM10 - AOD correlations over northern Italy. The accuracy of the new dataset is assessed compared to the widely used Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 5.1 Aerosol Optical Depth (AOD) data, retrieved at 0.55 μm with spatial resolution of 10 km (MYD04_L2). We focused on evaluating the ability of these two products to characterize both temporal and spatial distributions of aerosols within urban and suburban areas. Ground PM10 measurements were obtained from 73 of the Italian Regional Agency for Environmental Protection (ARPA) monitoring stations, spread across northern Italy, during a three-year period from 2010 to 2012. The Po Valley area (northern Italy) was chosen as the study domain because of its severe urban air pollution, resulting from it having the highest population and industrial manufacturing density in the country, being located in a valley where two surrounding mountain chains favor the stagnation of pollutants. We found that the global correlations between the bin-averaged PM10 and AOD are R2 = 0.83 and R2 = 0.44 for MYD04_L2 and for MAIAC, respectively, suggesting a greater sensitivity of the high-resolution product to small-scale deviations. However, the introduction of Relative Humidity (RH) and Planetary Boundary Layer (PBL) depth corrections allowed for a significant improvement to the bin-averaged PM - AOD correlation, which led to a similar performance: R2 = 0.96 for MODIS and R2 = 0.95 for MAIAC. Furthermore, the introduction of the PBL information in the corrected AOD values was found to be crucial in order to capture the clear seasonal cycle shown by measured PM10 values. The study allowed us to define four seasonal linear correlations that estimate PM10 concentrations satisfactorily from the remotely sensed MAIAC AOD retrieval. Overall, the results show that the high

  8. Estimation of the atmosphere-ocean fluxes of greenhouse gases and aerosols at the finer resolution of the coastal ocean.

    NASA Astrophysics Data System (ADS)

    Vieira, Vasco; Sahlée, Erik; Jurus, Pavel; Clementi, Emanuela; Pettersson, Heidi; Mateus, Marcos

    2016-04-01

    The balances and fluxes of greenhouse gases and aerosols between atmosphere and ocean are fundamental for Earth's heat budget. Hence, the scientific community needs to know and simulate them with accuracy in order to monitor climate change from Earth-Observation satellites and to produce reliable estimates of climate change using Earth-System Models (ESM). So far, ESM have represented earth's surface with coarser resolutions so that each cell of the marine domain is dominated by the open ocean. In such case it is enough to use simple algorithms considering the wind speed 10m above sea-surface (u10) as sole driver of the gas transfer velocity. The formulation by Wanninkhof (1992) is broadly accepted as the best. However, the ESM community is becoming increasingly aware of the need to model with finer resolutions. Then, it is no longer enough to only consider u10 when modelling gas transfer velocities across the coastal oceans' surfaces. More comprehensive formulations are required that adjust better to local conditions by also accounting for the effects of sea-surface agitation, wave breaking, atmospheric stability of the Surface Boundary Layer, current drag with the bottom, surfactants and rain. Accurate algorithms are also fundamental to monitor atmosphere and ocean greenhouse gas concentrations using satellite data and reverse modelling. Past satellite missions ERS, Envisat, Jason-2, Aqua, Terra and Metop, have already been remotely sensing the ocean's surface at much finer resolutions than ESM using instruments like MERIS, MODIS, AMR, AATSR, MIPAS, Poseidon-3, SCIAMACHY, SeaWiFS, and IASI. The planned new satellite missions Sentinel-3, OCO-2 and GOSAT will further increase the resolutions. We developed a framework to congregate competing formulations for the estimation of the solubility and transfer velocity of virtually any gas on the biosphere taking into consideration the atmosphere and ocean fundamental variables and their derived geophysical processes

  9. Comparing high-resolution daily gridded Precipitation data with satellite rainfall estimates of TRMM_3B42 over Iran

    NASA Astrophysics Data System (ADS)

    Javanmard, S.; Yatagai, A.; Kawamoto, H.; Nodzu, M. I.; Jamali, J. B.

    2009-04-01

    Information on spatial and temporal distribution of precipitation is important for drought monitoring, water resource management in agriculture, power generation and etc. In this respect, high-resolution gridded rainfall datasets are useful for regional studies on the hydrological cycle, climate variability, evaluation of regional models as well as satellite rainfall data. Iran receives rainfall from three major air masses throughout the year and the precipitation regime is complicated due to existence of two main mountain chains of the Zagros and the Alborz. High-resolution gridded precipitation can reproduce the precipitation distribution along the complicated topography and they could improve our understanding of precipitation regime as well a weather systems. Here, firstly we will present precipitation analysis over Iran (20°-45° N, 40°-65° E) based on high-resolution gridded rainfall datasets (0.25° × 0.25° lat./long.) from 1998 to 2006 utilizing synoptic observation data network of Islamic Republic of Iran Meteorological Organization (IRIMO). The number of synoptic stations used in this study are 256 and these data have passed quality control operations such as checking location (latitude, longitude and elevation), consistency to other meteorological parameters, test for homogeneity of data, filling data gaps and etc. by IRIMO. The algorithm of interpolation method of gridded precipitation data is based on the Shepard (1968). Secondly, the comparison of the above mentioned interpolated gridded precipitation data and daily rainfall estimates of TRMM(3B42_V6) which is TRMM Merged High Quality (HQ)/Infrared Precipitation without using raingauge data with spatial resolution 0.25 ° × 0.25° will be presented. From the above analysis results we have shown that spatial distribution of average of precipitation over Iran has two main precipitation pattern with maxima about 4 mm/day along Caspian sea and Zagros mountain chains. Moreover, comparison of spatial

  10. Estimating Percent Crystallinity of Polyethylene as a Function of Temperature by Raman Spectroscopy Multivariate Curve Resolution by Alternating Least Squares.

    PubMed

    Samuel, Ashok Zachariah; Lai, Bo-Han; Lan, Shih-Ting; Ando, Masahiro; Wang, Chien-Lung; Hamaguchi, Hiro-O

    2017-02-17

    We have recently demonstrated a methodology to estimate the percent crystallinity (PC) of polymers directly with Raman spectroscopy and multivariate curve resolution (MCR) by alternating least-squares (ALS). In the MCR-ALS methodology, the Raman spectrum of a semicrystalline polymer is separated into two constituent components (crystalline and molten/amorphous) and their corresponding concentrations. The methodology necessitates that the Raman spectrum at any temperature be a linear combination of two MCR spectral components (one molten and one crystalline). This is true in the case of simple systems such as crystalline pendant alkyl domains in polymers (Samuel et al. Anal. Chem. 2016, 88, 4644). However, in the case of main chain polymer crystals (e.g., polyethylene), the situation can be complicated owing to several molecular changes in the lattice in addition to conformational reorganizations during melting. Under this circumstance, a simple two-state model may not be adequate and we describe the modifications required to treat such systems, keeping the basic principles of the proposed methodology unchanged. A comparative study with wide-angle X-ray scattering (WAXS) and Raman spectroscopy is also performed to substantiate our findings. In addition to estimating percent crystallinity (PC), our methodology is capable of revealing additional information, such as interchain interactions in crystal lattice, that in principle will help distinguishing polymorphic transformations, subtle changes in lamellar lattice dimensions, and other phase changes in polymers.

  11. Use of Cokriging to Improve Spatial Resolution of Ambient Airborne Contaminant Concentration Estimates in Detroit and Windsor

    NASA Astrophysics Data System (ADS)

    Lemke, L. D.; Bobryk, S. M.; Xu, X.

    2010-12-01

    ; however, predictive performance for PM1-2.5 cokriged with NO2 was slightly degraded. Nevertheless, mapped results demonstrate that PAH and PM1-2.5 concentration surfaces generated with OCK maps have improved spatial resolution over OK maps and artifacts observed in the OK PAH map were appreciably reduced. As expected, the largest differences between estimation approaches occurred in areas with widely spaced samplers (i.e. where active samplers were excluded). Results suggest that cokriging with inexpensive passive air sampling data as secondary information can improve estimates of other analytes when economic and logistical considerations limit the number of active sampler locations.

  12. Using remote sensing products to classify landscape. A multi-spatial resolution approach

    NASA Astrophysics Data System (ADS)

    García-Llamas, Paula; Calvo, Leonor; Álvarez-Martínez, José Manuel; Suárez-Seoane, Susana

    2016-08-01

    The European Landscape Convention encourages the inventory and characterization of landscapes for environmental management and planning actions. Among the range of data sources available for landscape classification, remote sensing has substantial applicability, although difficulties might arise when available data are not at the spatial resolution of operational interest. We evaluated the applicability of two remote sensing products informing on land cover (the categorical CORINE map at 30 m resolution and the continuous NDVI spectral index at 1 km resolution) in landscape classification across a range of spatial resolutions (30 m, 90 m, 180 m, 1 km), using the Cantabrian Mountains (NW Spain) as study case. Separate landscape classifications (using topography, urban influence and land cover as inputs) were accomplished, one per each land cover dataset and spatial resolution. Classification accuracy was estimated through confusion matrixes and uncertainty in terms of both membership probability and confusion indices. Regarding landscape classifications based on CORINE, both typology and number of landscape classes varied across spatial resolutions. Classification accuracy increased from 30 m (the original resolution of CORINE) to 90m, decreasing towards coarser resolutions. Uncertainty followed the opposite pattern. In the case of landscape classifications based on NDVI, the identified landscape patterns were geographically structured and showed little sensitivity to changes across spatial resolutions. Only the change from 1 km (the original resolution of NDVI) to 180 m improved classification accuracy. The value of confusion indices increased with resolution. We highlight the need for greater effort in selecting data sources at the suitable spatial resolution, matching regional peculiarities and minimizing error and uncertainty.

  13. Estimating Size-Resolved Surface Particulate Matter Concentrations Using MISR High-Resolution Size-Fractionated Aerosol Optical Depth

    NASA Astrophysics Data System (ADS)

    Franklin, M.; Kalashnikova, O. V.; Garay, M. J.

    2015-12-01

    There is significant public health interest in gaining a better understanding of the health effects associated with particulate matter (PM) of different composition and size, yet ground-based monitoring data for such PM species is extremely limited. Due to their spatial and temporal coverage, satellite observations of total column aerosol optical depth (AOD) have increasingly been used to estimate surface concentrations of PM. While techniques for using satellite observations of AOD to predict surface concentrations of PM2.5 have been established, predicting surface concentrations of different particle sizes and species is more challenging. The Multi-angle Imaging SpectroRadiometer (MISR) instrument has the unique capability of estimating both total column AOD as well as total column size fractionated (small, medium and large) AOD. Using MISR AOD and AOD size fractionated products derived from high-resolution (275 m) observations reported at a spatial scale of 4.4 km in combination with national Air Quality System (AQS) monitoring data over the 2008-2009 period, we examine the association between size-fractionated MISR AOD and surface measurements of PM at different sizes (PM2.5 and PM10) and PM2.5 species (EC, OC, SO42-, NH4+) over the greater Los Angeles area. While there was a limited sample size of speciated PM data, the strongest univariate association found was between AOD and PM2.5 SO42- (R2=0.76). Incorporating meteorological data from weather stations in the area resulted in improvements to the models associating AOD with PM2.5 and PM10 mass. We found that PM2.5 was best predicted by a spatio-temporal model of AOD that also included dew point temperature and wind speed (R2=0.61), and that PM10 was best predicted by a spatio-temporal model of large fraction AOD that also included atmospheric pressure and wind speed (R2=0.65). These flexibly specified spatio-temporal models enabled reliable predictions of surface PM2.5 and PM10 concentrations at a 4.4km

  14. An Approach for the Long-Term 30-m Land Surface Snow-Free Albedo Retrieval from Historic Landsat Surface Reflectance and MODIS-based A Priori Anisotropy Knowledge

    NASA Technical Reports Server (NTRS)

    Shuai, Yanmin; Masek, Jeffrey G.; Gao, Feng; Schaaf, Crystal B.; He, Tao

    2014-01-01

    Land surface albedo has been recognized by the Global Terrestrial Observing System (GTOS) as an essential climate variable crucial for accurate modeling and monitoring of the Earth's radiative budget. While global climate studies can leverage albedo datasets from MODIS, VIIRS, and other coarse-resolution sensors, many applications in heterogeneous environments can benefit from higher-resolution albedo products derived from Landsat. We previously developed a "MODIS-concurrent" approach for the 30-meter albedo estimation which relied on combining post-2000 Landsat data with MODIS Bidirectional Reflectance Distribution Function (BRDF) information. Here we present a "pre-MODIS era" approach to extend 30-m surface albedo generation in time back to the 1980s, through an a priori anisotropy Look-Up Table (LUT) built up from the high quality MCD43A BRDF estimates over representative homogenous regions. Each entry in the LUT reflects a unique combination of land cover, seasonality, terrain information, disturbance age and type, and Landsat optical spectral bands. An initial conceptual LUT was created for the Pacific Northwest (PNW) of the United States and provides BRDF shapes estimated from MODIS observations for undisturbed and disturbed surface types (including recovery trajectories of burned areas and non-fire disturbances). By accepting the assumption of a generally invariant BRDF shape for similar land surface structures as a priori information, spectral white-sky and black-sky albedos are derived through albedo-to-nadir reflectance ratios as a bridge between the Landsat and MODIS scale. A further narrow-to-broadband conversion based on radiative transfer simulations is adopted to produce broadband albedos at visible, near infrared, and shortwave regimes.We evaluate the accuracy of resultant Landsat albedo using available field measurements at forested AmeriFlux stations in the PNW region, and examine the consistency of the surface albedo generated by this approach

  15. Estimating the gas transfer velocity: a prerequisite for more accurate and higher resolution GHG fluxes (lower Aare River, Switzerland)

    NASA Astrophysics Data System (ADS)

    Sollberger, S.; Perez, K.; Schubert, C. J.; Eugster, W.; Wehrli, B.; Del Sontro, T.

    2013-12-01

    Currently, carbon dioxide (CO2) and methane (CH4) emissions from lakes, reservoirs and rivers are readily investigated due to the global warming potential of those gases and the role these inland waters play in the carbon cycle. However, there is a lack of high spatiotemporally-resolved emission estimates, and how to accurately assess the gas transfer velocity (K) remains controversial. In anthropogenically-impacted systems where run-of-river reservoirs disrupt the flow of sediments by increasing the erosion and load accumulation patterns, the resulting production of carbonic greenhouse gases (GH-C) is likely to be enhanced. The GH-C flux is thus counteracting the terrestrial carbon sink in these environments that act as net carbon emitters. The aim of this project was to determine the GH-C emissions from a medium-sized river heavily impacted by several impoundments and channelization through a densely-populated region of Switzerland. Estimating gas emission from rivers is not trivial and recently several models have been put forth to do so; therefore a second goal of this project was to compare the river emission models available with direct measurements. Finally, we further validated the modeled fluxes by using a combined approach with water sampling, chamber measurements, and highly temporal GH-C monitoring using an equilibrator. We conducted monthly surveys along the 120 km of the lower Aare River where we sampled for dissolved CH4 (';manual' sampling) at a 5-km sampling resolution, and measured gas emissions directly with chambers over a 35 km section. We calculated fluxes (F) via the boundary layer equation (F=K×(Cw-Ceq)) that uses the water-air GH-C concentration (C) gradient (Cw-Ceq) and K, which is the most sensitive parameter. K was estimated using 11 different models found in the literature with varying dependencies on: river hydrology (n=7), wind (2), heat exchange (1), and river width (1). We found that chamber fluxes were always higher than boundary

  16. Generation of the 30 M-Mesh Global Digital Surface Model by Alos Prism

    NASA Astrophysics Data System (ADS)

    Tadono, T.; Nagai, H.; Ishida, H.; Oda, F.; Naito, S.; Minakawa, K.; Iwamoto, H.

    2016-06-01

    Topographical information is fundamental to many geo-spatial related information and applications on Earth. Remote sensing satellites have the advantage in such fields because they are capable of global observation and repeatedly. Several satellite-based digital elevation datasets were provided to examine global terrains with medium resolutions e.g. the Shuttle Radar Topography Mission (SRTM), the global digital elevation model by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER GDEM). A new global digital surface model (DSM) dataset using the archived data of the Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM) onboard the Advanced Land Observing Satellite (ALOS, nicknamed "Daichi") has been completed on March 2016 by Japan Aerospace Exploration Agency (JAXA) collaborating with NTT DATA Corp. and Remote Sensing Technology Center, Japan. This project is called "ALOS World 3D" (AW3D), and its dataset consists of the global DSM dataset with 0.15 arcsec. pixel spacing (approx. 5 m mesh) and ortho-rectified PRISM image with 2.5 m resolution. JAXA is also processing the global DSM with 1 arcsec. spacing (approx. 30 m mesh) based on the AW3D DSM dataset, and partially releasing it free of charge, which calls "ALOS World 3D 30 m mesh" (AW3D30). The global AW3D30 dataset will be released on May 2016. This paper describes the processing status, a preliminary validation result of the AW3D30 DSM dataset, and its public release status. As a summary of the preliminary validation of AW3D30 DSM, 4.40 m (RMSE) of the height accuracy of the dataset was confirmed using 5,121 independent check points distributed in the world.

  17. Estimating hydrodynamic roughness in a wave-dominated environment with a high-resolution acoustic Doppler profiler

    USGS Publications Warehouse

    Lacy, J.R.; Sherwood, C.R.; Wilson, D.J.; Chisholm, T.A.; Gelfenbaum, G.R.

    2005-01-01

    Hydrodynamic roughness is a critical parameter for characterizing bottom drag in boundary layers, and it varies both spatially and temporally due to variation in grain size, bedforms, and saltating sediment. In this paper we investigate temporal variability in hydrodynamic roughness using velocity profiles in the bottom boundary layer measured with a high-resolution acoustic Doppler profiler (PCADP). The data were collected on the ebb-tidal delta off Grays Harbor, Washington, in a mean water depth of 9 m. Significant wave height ranged from 0.5 to 3 m. Bottom roughness has rarely been determined from hydrodynamic measurements under conditions such as these, where energetic waves and medium-to-fine sand produce small bedforms. Friction velocity due to current u*c and apparent bottom roughness z0a were determined from the PCADP burst mean velocity profiles using the law of the wall. Bottom roughness kB was estimated by applying the Grant-Madsen model for wave-current interaction iteratively until the model u*c converged with values determined from the data. The resulting kB values ranged over 3 orders of magnitude (10-1 to 10-4 m) and varied inversely with wave orbital diameter. This range of kB influences predicted bottom shear stress considerably, suggesting that the use of time-varying bottom roughness could significantly improve the accuracy of sediment transport models. Bedform height was estimated from kB and is consistent with both ripple heights predicted by empirical models and bedforms in sonar images collected during the experiment. Copyright 2005 by the American Geophysical Union.

  18. A comprehensive filtering scheme for high-resolution estimation of the water balance components from high-precision lysimeters

    NASA Astrophysics Data System (ADS)

    Hannes, M.; Wollschlager, U.; Schrader, F.; Durner, W.; Gebler, S.; Putz, T.; Fank, J.; von Unold, G.; Vogel, H.-J.

    2015-08-01

    Large weighing lysimeters are currently the most precise method to directly measure all components of the terrestrial water balance in parallel via the built-in weighing system. As lysimeters are exposed to several external forces such as management practices or wind influencing the weighing data, the calculated fluxes of precipitation and evapotranspiration can be altered considerably without having applied appropriate corrections to the raw data. Therefore, adequate filtering schemes for obtaining most accurate estimates of the water balance components are required. In this study, we use data from the TERENO (TERrestrial ENvironmental Observatories) SoilCan research site in Bad Lauchstadt to develop a comprehensive filtering procedure for high-precision lysimeter data, which is designed to deal with various kinds of possible errors starting from the elimination of large disturbances in the raw data resulting e.g., from management practices all the way to the reduction of noise caused e.g., by moderate wind. Furthermore, we analyze the influence of averaging times and thresholds required by some of the filtering steps on the calculated water balance and investigate the ability of two adaptive filtering methods (the adaptive window and adaptive threshold filter (AWAT filter; Peters et al., 2014), and a new synchro filter applicable to the data from a set of several lysimeters) to further reduce the filtering error. Finally, we take advantage of the data sets of all 18 lysimeters running in parallel at the Bad Lauchstadt site to evaluate the performance and accuracy of the proposed filtering scheme. For the tested time interval of 2 months, we show that the estimation of the water balance with high temporal resolution and good accuracy is possible. The filtering code can be downloaded from the journal website as Supplement to this publication.

  19. Identification of recharge zones in the Lower Mississippi River alluvial aquifer using high-resolution precipitation estimates

    NASA Astrophysics Data System (ADS)

    Dyer, Jamie; Mercer, Andrew; Rigby, James R.; Grimes, Alexandria

    2015-12-01

    Water resources in the lower Mississippi River alluvial valley play a critical role in agricultural productivity due to the widespread use of irrigation during the growing season. However, the unknown specifics of surface-atmosphere feedbacks in the region, along with diminishing groundwater availability and the non-sustainable trend in irrigation draws from the alluvial aquifer, makes it difficult for water resource managers to make sound decisions for future water sustainability. As a result, it is crucial to identify spatial and temporal associations between local rainfall patterns and groundwater levels to determine the influence of precipitation on regional aquifer recharge. Specifically, it is critical to define the recharge zones of the aquifer so that rainfall distribution can be used to assess potential groundwater recovery. This project addresses the issue of defining areas of recharge in the lower Mississippi River alluvial aquifer (LMRAA) through an assessment of historical precipitation variability using high-resolution radar-derived precipitation estimates. A rotated principal component analysis (RPCA) of both groundwater and precipitation data from October through April is used to define locations where aquifer levels show the greatest variability, with a stepwise regression approach used to define areas where rainfall and groundwater levels show the strongest association. Results show that the greatest recharge through direct rainfall is along the Tallahatchie River basin in the northeastern Mississippi Delta, with recharge along the periphery of the LMRAA likely a result of direct water flux from surface hydrologic features.

  20. Estimation of high resolution shallow water bathymetry via two-media-photogrammetry - a case study at the Pielach River

    NASA Astrophysics Data System (ADS)

    Wimmer, Michael; Mandlburger, Gottfried; Ressl, Camillo; Pfeifer, Norbert

    2016-04-01

    In our contribution, a photogrammetric approach for water depth estimation of a shallow water body is developed and applied to a gravel-bed river in order to evaluate the possibilities of passive optical remote sensing for high resolution bathymetry. While 2-media (air and water) photogrammetry has been described before, it was concentrated on reconstruction of individual points. Here, we take a different approach and aim at a dense surface description of the river bed as seen from the aerial image through the water column. In a first step, the influence of light refraction at the boundary between two media for photogrammetric point retrieval is assessed. The effect is theoretically investigated under varying conditions, i.e. the 3D point displacement caused by refraction is related to parameters such as water depth, image geometry et cetera. Especially the assumption of a plain, horizontal water surface does not hold in practice. Therefore, also the limitations of the theoretical model are determined by investigating, how water surface waves and the corresponding deviation of the surface normal vectors from vertical direction distort the results. In the second, practical part of the work, a refraction correction procedure is derived from the prior investigations and is embedded into the photogrammetric workflow. A full photogrammetric processing chain is applied to a set of aerial images of the pre-Alpine Pielach River in Lower Austria. The RGB images were taken simultaneously to an Airborne Laser Bathymetry (ALB) campaign providing high resolution reference data. Based on these images, a Digital Terrain Model is derived for the open as well as the submerged areas. Running through the procedure gives important insights about the possibilities of influencing the processing pipeline of commercial photogrammetric software packages in order to apply the developed refraction correction. Especially, the deviation from the epipolar constraint caused by refraction and the

  1. The Influence of Data Resolution on Predicted Distribution and Estimates of Extent of Current Protection of Three ‘Listed’ Deep-Sea Habitats

    PubMed Central

    Ross, Lauren K.; Ross, Rebecca E.; Stewart, Heather A.; Howell, Kerry L.

    2015-01-01

    Modelling approaches have the potential to significantly contribute to the spatial management of the deep-sea ecosystem in a cost effective manner. However, we currently have little understanding of the accuracy of such models, developed using limited data, of varying resolution. The aim of this study was to investigate the performance of predictive models constructed using non-simulated (real world) data of different resolution. Predicted distribution maps for three deep-sea habitats were constructed using MaxEnt modelling methods using high resolution multibeam bathymetric data and associated terrain derived variables as predictors. Model performance was evaluated using repeated 75/25 training/test data partitions using AUC and threshold-dependent assessment methods. The overall extent and distribution of each habitat, and the percentage contained within an existing MPA network were quantified and compared to results from low resolution GEBCO models. Predicted spatial extent for scleractinian coral reef and Syringammina fragilissima aggregations decreased with an increase in model resolution, whereas Pheronema carpenteri total suitable area increased. Distinct differences in predicted habitat distribution were observed for all three habitats. Estimates of habitat extent contained within the MPA network all increased when modelled at fine scale. High resolution models performed better than low resolution models according to threshold-dependent evaluation. We recommend the use of high resolution multibeam bathymetry data over low resolution bathymetry data for use in modelling approaches. We do not recommend the use of predictive models to produce absolute values of habitat extent, but likely areas of suitable habitat. Assessments of MPA network effectiveness based on calculations of percentage area protection (policy driven conservation targets) from low resolution models are likely to be fit for purpose. PMID:26496639

  2. The Influence of Data Resolution on Predicted Distribution and Estimates of Extent of Current Protection of Three 'Listed' Deep-Sea Habitats.

    PubMed

    Ross, Lauren K; Ross, Rebecca E; Stewart, Heather A; Howell, Kerry L

    2015-01-01

    Modelling approaches have the potential to significantly contribute to the spatial management of the deep-sea ecosystem in a cost effective manner. However, we currently have little understanding of the accuracy of such models, developed using limited data, of varying resolution. The aim of this study was to investigate the performance of predictive models constructed using non-simulated (real world) data of different resolution. Predicted distribution maps for three deep-sea habitats were constructed using MaxEnt modelling methods using high resolution multibeam bathymetric data and associated terrain derived variables as predictors. Model performance was evaluated using repeated 75/25 training/test data partitions using AUC and threshold-dependent assessment methods. The overall extent and distribution of each habitat, and the percentage contained within an existing MPA network were quantified and compared to results from low resolution GEBCO models. Predicted spatial extent for scleractinian coral reef and Syringammina fragilissima aggregations decreased with an increase in model resolution, whereas Pheronema carpenteri total suitable area increased. Distinct differences in predicted habitat distribution were observed for all three habitats. Estimates of habitat extent contained within the MPA network all increased when modelled at fine scale. High resolution models performed better than low resolution models according to threshold-dependent evaluation. We recommend the use of high resolution multibeam bathymetry data over low resolution bathymetry data for use in modelling approaches. We do not recommend the use of predictive models to produce absolute values of habitat extent, but likely areas of suitable habitat. Assessments of MPA network effectiveness based on calculations of percentage area protection (policy driven conservation targets) from low resolution models are likely to be fit for purpose.

  3. Estimation of the effective and functional human cortical connectivity with structural equation modeling and directed transfer function applied to high-resolution EEG.

    PubMed

    Astolfi, Laura; Cincotti, Febo; Mattia, Donatella; Salinari, Serenella; Babiloni, Claudio; Basilisco, Alessandra; Rossini, Paolo Maria; Ding, Lei; Ni, Ying; He, Bin; Marciani, Maria Grazia; Babiloni, Fabio

    2004-12-01

    Different brain imaging devices are presently available to provide images of the human functional cortical activity, based on hemodynamic, metabolic or electromagnetic measurements. However, static images of brain regions activated during particular tasks do not convey the information of how these regions are interconnected. The concept of brain connectivity plays a central role in the neuroscience, and different definitions of connectivity, functional and effective, have been adopted in literature. While the functional connectivity is defined as the temporal coherence among the activities of different brain areas, the effective connectivity is defined as the simplest brain circuit that would produce the same temporal relationship as observed experimentally among cortical sites. The structural equation modeling (SEM) is the most used method to estimate effective connectivity in neuroscience, and its typical application is on data related to brain hemodynamic behavior tested by functional magnetic resonance imaging (fMRI), whereas the directed transfer function (DTF) method is a frequency-domain approach based on both a multivariate autoregressive (MVAR) modeling of time series and on the concept of Granger causality. This study presents advanced methods for the estimation of cortical connectivity by applying SEM and DTF on the cortical signals estimated from high-resolution electroencephalography (EEG) recordings, since these signals exhibit a higher spatial resolution than conventional cerebral electromagnetic measures. To estimate correctly the cortical signals, we used a subject's multicompartment head model (scalp, skull, dura mater, cortex) constructed from individual MRI, a distributed source model and a regularized linear inverse source estimates of cortical current density. Before the application of SEM and DTF methodology to the cortical waveforms estimated from high-resolution EEG data, we performed a simulation study, in which different main factors

  4. A High-Resolution Two-Stage Satellite Model to Estimate PM2.5 Concentrations in China

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Ma, Z.; Hu, X.; Yang, K.

    2014-12-01

    With the rapid economic development and urbanization, severe and widespread PM2.5 pollution in China has attracted nationwide attention. Study of the health impact of PM2.5 exposure has been hindered, however, by the limited coverage of ground measurements from recently established regulatory monitoring networks. Estimating ground-level PM2.5 from satellite remote sensing is a promising new method to evaluate the spatial and temporal patterns of PM2.5 exposure. We developed a two-stage spatial statistical model to estimate daily mean PM2.5 concentrations at 10 km resolution in 2013 in China using MODIS Collection 6 AOD, assimilated meteorology, population density, and land use parameters. A custom inverse variance weighting approach was developed to combine MODIS Dark Target (DT) and Deep Blue (DB) AOD to optimize coverage. Compared with the AERONET AOD measurements, our combined AOD (R2=0.80, mean bias = 0.07) performs similarly to MODIS' combined AOD (R2=0.81, mean bias =0.07), but has 90% greater coverage. We used the first-stage linear mixed effect model to represent the temporal variability of PM2.5 and the second-stage generalized additive model to represent its spatial contrast. The overall model cross-validation R2 and relative prediction error are 0.80 and 30%, respectively. PM2.5 levels exhibit strong seasonal patterns, with the highest national mean concentrations in winter (75 µg/m3) and the lowest in summer (30 µg/m3). Elevated annual mean PM2.5 levels are predicted in North China Plain and Sichuan Basin, with the maximum annual PM2.5 concentrations higher than 130 µg/m3 and 110 µg/m3, respectively. Our results also indicates that over 94% of the Chinese population lives in areas that exceed the WHO Air Quality Interim Target-1 standard (35 μg/m3). The exceptions include Taiwan, Hainan, Yunnan, Tibet, and North Inner Mongolia.

  5. An Evaluation of New High-Resolution Image Collection and Processing Techniques for Estimating Shrub Cover and Detecting Landscape Changes

    SciTech Connect

    Hansen, D.J.; Ostler, W.K.

    2001-05-01

    Research funded by the U.S. Department of Defense (DoD), U.S. Department of Energy (DOE), and the U.S. Environmental Protection Agency as part of the Strategic Environmental Research and Development Program (SERDP) evaluated novel techniques for collecting and processing high-resolution images in the Mojave Desert. Several camera types, lens, films, and digital processing techniques were evaluated on the basis of their ability to correctly estimate canopy cover of shrubs. A high degree of accuracy was obtained with photo scales of 1:1000 to 1:4000 and flatbed scanning rates from films or prints of 300 lines per inch or larger. Smaller scale images were of value in detecting retrospective changes in cover of large shrubs, but failed to detect smaller shrubs. New image-processing software, typically used in light microscopy, forensics, and industrial engineering, make it possible to accurately measure areas for total cover of up to four dominant shrub species in minutes compared to hours or days of field work. Canopy cover and individual shrub parameters such as width, length, circumference, and shape factors can be readily measured yielding size distribution histograms and other statistical data on plant community structure. These novel techniques are being evaluated in a four-year study of military training impacts at Fort Irwin, California. Results will be compared among the new and conventional imagery and processing, including 1-meter (m) pixel IKONOS images. The new processes create georectified color-coded contour maps of shrub cover for use with Geographic Information System (GIS) software. The technique is a valuable new emerging tool to accurately assess vegetation structure and landscape changes due to military or other land-use disturbances.

  6. Design and Expected Performance of GISMO-2, a Two Color Millimeter Camera for the IRAM 30 m Telescope

    NASA Technical Reports Server (NTRS)

    Staguhn, Johannes G.; Benford, Dominic J.; Dwek, Eli; Hilton, Gene; Fixsen, Dale J.; Irwin, Kent; Jhabvala, Christine; Kovacs, Attila; Leclercq, Samuel; Maher, Stephen F.; Miller, Tim; Moseley, S. Harvey; Sharp, Elmer H.; Wollack, Edward

    2014-01-01

    We present the main design features for the GISMO-2 bolometer camera, which we build for background-limited operation at the IRAM 30 m telescope on Pico Veleta, Spain. GISMO-2 will operate simultaneously in the 1 and 2 mm atmospherical windows. The 1 mm channel uses a 32 × 40 TES-based backshort under grid (BUG) bolometer array, the 2 mm channel operates with a 16 × 16 BUG array. The camera utilizes almost the entire full field of view provided by the telescope. The optical design of GISMO-2 was strongly influenced by our experience with the GISMO 2mm bolometer camera, which is successfully operating at the 30 m telescope. GISMO is accessible to the astronomical community through the regularIRAMcall for proposals.

  7. A New Folding Kinetic Mechanism for Human Transthyretin and the Influence of the Amyloidogenic V30M Mutation

    PubMed Central

    Jesus, Catarina S. H.; Almeida, Zaida L.; Vaz, Daniela C.; Faria, Tiago Q.; Brito, Rui M. M.

    2016-01-01

    Protein aggregation into insoluble amyloid fibrils is the hallmark of several neurodegenerative diseases, chief among them Alzheimer’s and Parkinson’s. Although caused by different proteins, these pathologies share some basic molecular mechanisms with familial amyloidotic polyneuropathy (FAP), a rare hereditary neuropathy caused by amyloid formation and deposition by transthyretin (TTR) in the peripheral and autonomic nervous systems. Among the amyloidogenic TTR mutations known, V30M-TTR is the most common in FAP. TTR amyloidogenesis (ATTR) is triggered by tetramer dissociation, followed by partial unfolding and aggregation of the low conformational stability monomers formed. Thus, tetramer dissociation kinetics, monomer conformational stability and competition between refolding and aggregation pathways do play a critical role in ATTR. Here, we propose a new model to analyze the refolding kinetics of WT-TTR and V30M-TTR, showing that at pH and protein concentrations close to physiological, a two-step mechanism with a unimolecular first step followed by a second-order second step adjusts well to the experimental data. Interestingly, although sharing the same kinetic mechanism, V30M-TTR refolds at a much slower rate than WT-TTR, a feature that may favor the formation of transient species leading to kinetic partition into amyloidogenic pathways and, thus, significantly increasing the probability of amyloid formation in vivo. PMID:27589730

  8. Electronic Structure of I-M8Ga16Sn30 (M = Ba, Sr, Yb) by First-Principles Calculation

    NASA Astrophysics Data System (ADS)

    Wang, Jin-song; Liu, Hong-xia; Deng, Shuping; Li, De-cong; Shen, Lan-xian; Cheng, Feng; Deng, Shu-kang

    2016-10-01

    Sn-based clathrates possess excellent thermoelectric properties ascribed to their higher Seebeck coefficient and lower thermal conductivity. Guest atoms significantly modulate the thermoelectric properties of Sn-based calculates because of their diverse atomic radius and interactions with framework atoms. Thus, we explored the electronic structure of I-M8Ga16Sn30 (M = Ba, Sr, Yb) by first-principles calculation. Results revealed significant differences between Yb8Ga16Sn30 and M8Ga16Sn30 (M = Ba, Sr,). In particular, the Yb-filled compound substitution possesses lowest formation energy and the off-center distance of the Yb atom is the largest compared with the other structures. I-M8Ga16Sn30 (M = Ba, Sr, Yb) is an indirect band gap semiconductor, and the enhanced hybridization effect between the guest and framework atoms' orbits exists because the Yb f orbit results in a decrease in band gap. Ba- and Sr-filled clathrates have similar valence bands but slightly different conduction bands; however, Yb8Ga16Sn30 possess the spiculate density of states near the Fermi level that reveals excellent thermoelectric properties.

  9. Efficiency of silencing RNA for removal of transthyretin V30M in a TTR leptomeningeal animal model.

    PubMed

    Gonçalves, Paula; Martins, Helena; Costelha, Susete; Maia, Luis F; Saraiva, Maria Joao

    2016-12-01

    Some TTR mutants target the central nervous system (CNS). Familial amyloid polyneuropathy (FAP) with leptomeningeal involvement has been described in 9% of transthyretin (TTR) mutations and in valine for methionine at position 30 (V30M) patients. These individuals present dementia, ataxia, brain hemorrhages and focal neurological episodes (FNEs). FNEs occurred also in V30M FAP patients with longer disease duration, who have undergone liver transplant to remove the source of plasma mutant TTR as a form of treatment. It is thus to expect that as better treatments for FAP emerge and prolong survival, meningeal-vascular CNS deposition will increase and need special therapies. Recently, we detected TTR meningeal-vascular deposition in a V30M TTR transgenic mouse model, opening new avenues of research to investigate selective treatments of this condition. Since pre-clinical studies with TTR siRNA therapeutics were shown to promote clearance of TTR non-fibrillar deposits in several organs and tissues, we investigated its effect on TTR meningeal-vascular deposition. We show that systemically administered TTR siRNA promoted TTR clearance in the extracellular matrix of meninges and brain blood vessels. Surprisingly, despite the striking decline of blood TTR, cerebrospinal fluid TTR levels were unaffected. Though this is reassuring because siRNA will not interfere with the neuroprotective role of TTR in the CNS, it raises new questions on therapeutical approaches for CNS ATTR.

  10. Long-term treatment of anemia with recombinant human erythropoietin in familial amyloidosis TTR V30M.

    PubMed

    Beirão, Idalina; Lobato, Luísa; Moreira, Luciana; Mp Costa, Paulo; Fonseca, Isabel; Cabrita, António; Porto, Graça

    2008-09-01

    Familial amyloidosis or familial amyloid polyneuropathy (FAP) TTR V30M is a hereditary disease presented, in most cases, as a sensorimotor and autonomic neuropathy. Normocytic and normochromic anaemia was found in 24.8% of symptomatic FAP patients associated to lower serum erythropoietin (Epo) levels. Erythropoietin has been reported as efficient in anaemia correction in this disease. To evaluate the tolerance and efficacy of this treatment, a retrospective longitudinal study with 24 patients was undertaken. Patients were followed for at least 6 months. Haemoglobin, hematocrit, iron status, serum creatinine and urea and r-HuEPO doses were monitored, at 0, 3 months, 6 months and at the end of the follow-up. Long-term use of r-HuEPO proved to be efficient in the treatment of anaemia in familial amyloidosis TTR V30M and, despite the disease progression, no resistance cases to this treatment were observed. Positive side effects, like improvement on orthostatic hypotension symptoms and well-being sensation, contributing to confirm erythropoietin as a drug of choice to treat anaemia in amyloidosis TTR V30M.

  11. Towards a Methodology for Estimating Surface Pollutant Mixing Ratios from High Spatial and Temporal Resolution Retrievals, and its Applicability to High-Resolution Space Based Observations

    NASA Astrophysics Data System (ADS)

    Knepp, T.; Pippin, M.; Crawford, J.; Szykman, J.; Long, R.; Neil, D.; Fishman, J.

    2012-11-01

    A ground-based sun-tracking spectrometer system (Pandora) is used to retrieve high time and spatial resolution total-column nitrogen dioxide. These column observations are compared with data from a surface NOx instrument that employs a photolytic converter. The column data are inverted (via the EDAS-40 model) to yield surface mole fractions (i.e.ppb) that have typically high coefficients of correlation (e.g. R = 0.80) with surface data. Translating these column observations into boundary-layer mole fractions provides a direct NO2 data set that can significantly improve the understanding of emission, chemical transportation, effectiveness of control strategies, and predictive capabilities. Preliminary results regarding the relation of surface and column NO2 were presented. Total-column NO2 was recorded using a Pandora sun-tracking spectrometer system [1]. The Pandora instrument provides high-temporal resolution data, with a retrieval done every ~90s under clear-sky conditions. Surface NO2 was recorded using a Teledyne API 200EU with a photolytic converter.

  12. The link between a negative high resolution resist contrast/developer performance and the Flory-Huggins parameter estimated from the Hansen solubility sphere

    SciTech Connect

    StCaire, Lorri; Olynick, Deirdre L.; Chao, Weilun L.; Lewis, Mark D.; Lu, Haoren; Dhuey, Scott D.; Liddle, J. Alexander

    2008-07-01

    We have implemented a technique to identify candidate polymer solvents for spinning, developing, and rinsing for a high resolution, negative electron beam resist hexa-methyl acetoxy calix(6)arene to elicit the optimum pattern development performance. Using the three dimensional Hansen solubility parameters for over 40 solvents, we have constructed a Hansen solubility sphere. From this sphere, we have estimated the Flory Huggins interaction parameter for solvents with hexa-methyl acetoxy calix(6)arene and found a correlation between resist development contrast and the Flory-Huggins parameter. This provides new insights into the development behavior of resist materials which are necessary for obtaining the ultimate lithographic resolution.

  13. Estimating KIR Haplotype Frequencies on a Cohort of 10,000 Individuals: A Comprehensive Study on Population Variations, Typing Resolutions, and Reference Haplotypes

    PubMed Central

    Jayaraman, Jyothi; Trowsdale, John; Traherne, James; Kuang, Rui; Spellman, Stephen; Maiers, Martin

    2016-01-01

    The killer cell immunoglobulin-like receptors (KIR) mediate human natural killer (NK) cell cytotoxicity via activating or inhibiting signals. Although informative and functional haplotype patterns have been reported, most genotyping has been performed at resolutions that are structurally ambiguous. In order to leverage structural information given low-resolution genotypes, we performed experiments to quantify the effects of population variations, reference haplotypes, and genotyping resolutions on population-level haplotype frequency estimations as well as predictions of individual haplotypes. We genotyped 10,157 unrelated individuals in 5 populations (518 African American[AFA], 258 Asian or Pacific Islander[API], 8,245 European[EUR], 1,073 Hispanic[HIS], and 63 Native American[NAM]) for KIR gene presence/absence (PA), and additionally half of the AFA samples for KIR gene copy number variation (CNV). A custom EM algorithm was used to estimate haplotype frequencies for each population by interpretation in the context of three sets of reference haplotypes. The algorithm also assigns each individual the haplotype pairs of maximum likelihood. Generally, our haplotype frequency estimates agree with similar previous publications to within <5% difference for all haplotypes. The exception is that estimates for NAM from the U.S. showed higher frequency association of cB02 with tA01 (+14%) instead of tB01 (-8.5%) compared to a previous study of NAM from south of the U.S. The higher-resolution CNV genotyping on the AFA samples allowed unambiguous haplotype-pair assignments for the majority of individuals, resulting in a 22% higher median typing resolution score (TRS), which measures likelihood of self-match in the context of population-specific haplo- and geno-types. The use of TRS to quantify reduced ambiguity with CNV data clearly revealed the few individuals with ambiguous genotypes as outliers. It is observed that typing resolution and reference haplotype set influence

  14. AN EVALUATION OF TWO GROUND-BASED CROWN CLOSURE ESTIMATION TECHNIQUES COMPARED TO CROWN CLOSURE ESTIMATES DERIVED FROM HIGH RESOLUTION IMAGERY

    EPA Science Inventory

    Two ground-based canopy closure estimation techniques, the Spherical Densitometer (SD) and the Vertical Tube (VT), were compared for the effect of deciduous understory on dominant/co-dominant crown closure estimates in even-aged loblolly (Pinus taeda) pine stands located in the N...

  15. Errors in the estimation of approximate entropy and other recurrence-plot-derived indices due to the finite resolution of RR time series.

    PubMed

    García-González, Miguel A; Fernández-Chimeno, Mireya; Ramos-Castro, Juan

    2009-02-01

    An analysis of the errors due to the finite resolution of RR time series in the estimation of the approximate entropy (ApEn) is described. The quantification errors in the discrete RR time series produce considerable errors in the ApEn estimation (bias and variance) when the signal variability or the sampling frequency is low. Similar errors can be found in indices related to the quantification of recurrence plots. An easy way to calculate a figure of merit [the signal to resolution of the neighborhood ratio (SRN)] is proposed in order to predict when the bias in the indices could be high. When SRN is close to an integer value n, the bias is higher than when near n - 1/2 or n + 1/2. Moreover, if SRN is close to an integer value, the lower this value, the greater the bias is.

  16. Estimation of the electron beam-induced specimen heating and the emitted X-rays spatial resolution by Kossel microdiffraction in a scanning electron microscope.

    PubMed

    Bouscaud, Denis; Pesci, Raphaël; Berveiller, Sophie; Patoor, Etienne

    2012-04-01

    A Kossel microdiffraction experimental setup has been developed inside a Scanning Electron Microscope for crystallographic orientation, strain and stress determination at a micrometer scale. This paper reports an estimation of copper and germanium specimens heating due to the electron beam bombardment. The temperature rise is calculated from precise lattice parameters measurement considering different currents induced in the specimens. The spatial resolution of the technique is then deduced.

  17. Use of High-Resolution Multispectral Imagery to Estimate Soil and Plant Nitrogen in Oats (Avena sativa)

    NASA Astrophysics Data System (ADS)

    ELarab, M.; Ticlavilca, A. M.; Torres-Rua, A. F.; McKee, M.

    2014-12-01

    Precision agriculture requires high spatial resolution in the application of the inputs to agricultural production. This requires that actionable information about crop and field status be acquired at the same high spatial resolution and at a temporal frequency appropriate for timely responses. In this study, high-resolution imagery was obtained through the use of a small, unmanned aerial vehicle, called AggieAirTM, which provides spatial resolution as fine as 15 cm. Simultaneously with AggieAir flights, intensive ground sampling was conducted at precisely determined locations for plant and soil nitrogen among other parameters. This study investigated the spectral signature of oats and formulated a machine learning regression model of reflectance response between the multi-spectral bands available from AggieAir (red, green, blue, near infrared, and thermal), plant nitrogen and soil nitrogen. A multivariate relevance vector machine (MVRVM) was used to develop the linkages between the remotely sensed data and plant and soil nitrogen at approximately 15-cm resolution. The results of this study are presented, including a statistical evaluation of the performance of the model.

  18. Using Very High Resolution Remotely Sensed Imagery to Estimate Agricultural Production: A comparison of food insecure and secure growing areas in Kenya

    NASA Astrophysics Data System (ADS)

    Grace, K.; Husak, G. J.; Bogle, S.

    2013-12-01

    Determining the amount of food produced in a food insecure, isolated, subsistence farming community can be used to help identify households or communities who may be in need of additional food resources. Measuring annual food production in developing countries, much less at a sub-national level, is complicated by lack of data. It can be difficult and costly to access all of the farming households engaged in subsistence farming. However, recent research has focused on the use of remotely sensed data to aid in the estimation of area under cultivation and because food production is the measure of yield (production per hectare) multiplied by area (number of hectares), we can use the area measure to reduce uncertainty in food production estimates. One strategy for estimating cultivated area relies on a fairly time intensive manual interpretation of very high resolution data. Due to the availability of very high resolution data it is possible to construct estimates of cultivated area, even in communities where fields are small. While this strategy has been used to effectively estimate cultivated area in a timely manner, questions remain about the spatial and temporal generalizability of this approach. The purpose of this paper is to produce and compare estimates of cultivated area in two very different agricultural areas of Kenya, a highly food insecure country in East Africa, during two different agricultural seasons. The areas selected represent two different livelihood zones: a marginal growing area where poor farmers rely on inconsistent rainfall and a lush growing area near the mountainous region of the middle-West area of the country where rainfall is consistent and therefore more suited to cultivation. The overarching goal is to determine the effectiveness of very high resolution remotely sensed imagery in calculating estimates of cultivated area in areas where food production strategies are different. Additionally the results of this research will explore the

  19. Estimation of the cortical functional connectivity with the multimodal integration of high-resolution EEG and fMRI data by directed transfer function.

    PubMed

    Babiloni, F; Cincotti, F; Babiloni, C; Carducci, F; Mattia, D; Astolfi, L; Basilisco, A; Rossini, P M; Ding, L; Ni, Y; Cheng, J; Christine, K; Sweeney, J; He, B

    2005-01-01

    Nowadays, several types of brain imaging device are available to provide images of the functional activity of the cerebral cortex based on hemodynamic, metabolic, or electromagnetic measurements. However, static images of brain regions activated during particular tasks do not convey the information of how these regions communicate with each other. In this study, advanced methods for the estimation of cortical connectivity from combined high-resolution electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) data are presented. These methods include a subject's multicompartment head model (scalp, skull, dura mater, cortex) constructed from individual magnetic resonance images, multidipole source model, and regularized linear inverse source estimates of cortical current density. Determination of the priors in the resolution of the linear inverse problem was performed with the use of information from the hemodynamic responses of the cortical areas as revealed by block-designed (strength of activated voxels) fMRI. We estimate functional cortical connectivity by computing the directed transfer function (DTF) on the estimated cortical current density waveforms in regions of interest (ROIs) on the modeled cortical mantle. The proposed method was able to unveil the direction of the information flow between the cortical regions of interest, as it is directional in nature. Furthermore, this method allows to detect changes in the time course of information flow between cortical regions in different frequency bands. The reliability of these techniques was further demonstrated by elaboration of high-resolution EEG and fMRI signals collected during visually triggered finger movements in four healthy subjects. Connectivity patterns estimated for this task reveal an involvement of right parietal and bilateral premotor and prefrontal cortical areas. This cortical region involvement resembles that revealed in previous studies where visually triggered finger

  20. Cotton yield estimation using very high-resolution digital images acquired on a low-cost small unmanned aerial vehicle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Yield estimation is a critical task in crop management. A number of traditional methods are available for crop yield estimation but they are costly, time-consuming and difficult to expand to a relatively large field. Remote sensing provides techniques to develop quick coverage over a field at any sc...

  1. RESOLUTION AND ERROR IN MEASURING LAND-COVER CHANGE: EFFECTS ON ESTIMATING NET CARBON RELEASE FROM MEXICAN TERRESTRIAL ECOSYSTEMS

    EPA Science Inventory

    Reliable estimates of carbon exchange between terrestrial ecosystems and the atmosphere due to land-use change have become increasingly important. One source of land-use changes estimates comes from comparing multi-date remote sensing imagery, though the effect of land-cover clas...

  2. Persistent patterns of interconnection in time-varying cortical networks estimated from high-resolution EEG recordings in humans during a simple motor act

    NASA Astrophysics Data System (ADS)

    DeVico Fallani, F.; Latora, V.; Astolfi, L.; Cincotti, F.; Mattia, D.; Marciani, M. G.; Salinari, S.; Colosimo, A.; Babiloni, F.

    2008-06-01

    In this work, a novel approach based on the estimate of time-varying graph indices is proposed in order to capture the basic schemes of communication within the functional brain networks during a simple motor act. To achieve this, we used a cascade of computational tools able to estimate first the electrical activity of the cortical surface by using high-resolution EEG techniques. From the cortical signals of different regions of interests we estimated the time-varying functional connectivity patterns by means of the adaptive partial directed coherence. The time-varying connectivity estimation returns a series of networks evolving during the examined task which can be summarized and interpreted with the aid of mathematical indices based on graph theory. The combination of all these methods is demonstrated on a set of high-resolution EEG data recorded from a group of healthy subjects performing a simple foot movement. It can be anticipated that the combination of the time-varying connectivity with the theoretical graph analysis is able to reveal precious information about the interconnections of the cerebral network as the significant persistence of mutual links and three-node motifs.

  3. Image interpreter tool: An ArcGIS tool for estimating vegetation cover from high-resolution imagery

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Land managers need increased temporal and spatial resolution of rangeland assessment and monitoring data. However, with flat or declining land management and monitoring agency budgets, such increases in sampling intensity are unlikely unless new methods can be developed that capture data of key rang...

  4. Estimation of surface energy balance from radiant surface temperature and NOAA AVHRR sensor reflectances over agricultural and native vegetation. [AVHRR (advanced very high resolution radiometer)

    SciTech Connect

    Huang Xinmei; Lyons, T.J. ); Smith, R.C.G. ); Hacker, J.M.; Schwerdtfeger, P. )

    1993-08-01

    A model is developed to evaluate surface heat flux densities using the radiant surface temperature and red and near-infrared reflectances from the NOAA Advanced Very High Resolution Radiometer sensor. Net radiation is calculated from an empirical formulation and albedo estimated from satellite observations. Infrared surface temperature is corrected to aerodynamic surface temperature in estimating the sensible heat flux and the latent flux is evaluated as the residual of the surface energy balance. When applied to relatively homogeneous agricultural and native vegetation, the model yields realistic estimates of sensible and latent heat flux density in the surface layer for cases where either the sensible or latent flux dominates. 29 refs., 10 figs., 3 tabs.

  5. Estimation of position resolution for DOI-PET detector using diameter 0.2 mm WLS fibers [ANIMMA--2015-IO-x5

    SciTech Connect

    Kaneko, Naomi; Ito, H.; Han, S.; Kawai, H.; Kodama, S.; Kobayashi, A.; Tabata, M.; Kamada, K.; Shoji, Y.; Yoshikawa, A.

    2015-07-01

    We have been developing a submillimeter resolution and low-cost DOI-PET detector using wavelength shifting fibers (WLSF), scintillating crystal plates and MPPCs (Hamamatsu Photonics). Conventional design of DOI-PET detectors had approximately mm{sup 3} of resolution by using some scintillating blocks with a volume of 1 mm{sup 3}, which detects gamma-ray. They are expensive due to difficulties in processing scintillating crystals and a large number of photo-detectors, and these technologies are likely to reach the limit of the resolution. Development of a lower cost DOI-PET detector with higher resolution is challenging to popularize the PET diagnosis. We propose two type of PET detector. One is a whole body PET system, and the other is a PET system for brain or small animals. Each PET system consists 6 blocks. The former consists of 6 layers of crystal plates with 300 mm x 300 mm x 4 mm. The latter consists of 16 crystal layers, forming 4 x 4 crystal arrays. The size of the crystal plate is 40 mm x 40 mm x 1 mm. Wavelength shifting fiber (WLSF) sheets are attached to above and up and down side of crystal planes. The whole PET system has 8 MPPCs attached on each side. For the brain PET detector, 9 WLSF fibers are attached on the each side. The expected position resolution would be less than 1 mm at the former system. We have performed an experimental performance estimation for the system component using {sup 22}Na radioactive source. We achieved a collection efficiency of 10% using the WLSF sheet and Ce:Gd{sub 3}(Al,Ga){sub 5}O{sub 12} (GAGG) crystals at 511 keV. The linear relationship between reconstruction position and incident position was obtained, and a resolution of 0.7 mm (FWHM) for x-axis of DOI by the WLSF readout was achieved. (authors)

  6. CEH-GEAR: 1 km resolution daily and monthly areal rainfall estimates for the UK for hydrological use

    NASA Astrophysics Data System (ADS)

    Keller, V. D. J.; Tanguy, M.; Prosdocimi, I.; Terry, J. A.; Hitt, O.; Cole, S. J.; Fry, M.; Morris, D. G.; Dixon, H.

    2015-01-01

    The Centre for Ecology & Hydrology - Gridded Estimates of Areal Rainfall (CEH-GEAR) dataset was developed to provide reliable 1 km gridded estimates of daily and monthly rainfall for Great Britain (GB) and Northern Ireland (NI) (together with approximately 3500 km2 of catchment in the Republic of Ireland) from 1890 onwards. The dataset was primarily required to support hydrological modelling. The rainfall estimates are derived from the Met Office collated historical weather observations for the UK which include a national database of raingauge observations. The natural neighbour interpolation methodology, including a normalisation step based on average annual rainfall, was used to generate the daily and monthly rainfall grids. To derive the monthly estimates, rainfall totals from monthly and daily (when complete month available) read raingauges were used in order to obtain maximum information from the raingauge network. The daily grids were adjusted so that the monthly grids are fully consistent with the daily grids. The CEH-GEAR dataset was developed according to the guidance provided by the British Standards Institution. The CEH-GEAR dataset contains 1 km grids of daily and monthly rainfall estimates for GB and NI for the period 1890-2012. For each day and month, CEH-GEAR includes a secondary grid of distance to the nearest operational raingauge. This may be used as an indicator of the quality of the estimates. When this distance is greater than 100 km, the estimates are not calculated due to high uncertainty. CEH-GEAR is available free of charge for commercial and non-commercial use subject to licensing terms and conditions. doi:10.5285/5dc179dc-f692-49ba-9326-a6893a503f6e

  7. CEH-GEAR: 1 km resolution daily and monthly areal rainfall estimates for the UK for hydrological and other applications

    NASA Astrophysics Data System (ADS)

    Keller, V. D. J.; Tanguy, M.; Prosdocimi, I.; Terry, J. A.; Hitt, O.; Cole, S. J.; Fry, M.; Morris, D. G.; Dixon, H.

    2015-06-01

    The Centre for Ecology & Hydrology - Gridded Estimates of Areal Rainfall (CEH-GEAR) data set was developed to provide reliable 1 km gridded estimates of daily and monthly rainfall for Great Britain (GB) and Northern Ireland (NI) (together with approximately 3500 km2 of catchment in the Republic of Ireland) from 1890 onwards. The data set was primarily required to support hydrological modelling. The rainfall estimates are derived from the Met Office collated historical weather observations for the UK which include a national database of rain gauge observations. The natural neighbour interpolation methodology, including a normalisation step based on average annual rainfall (AAR), was used to generate the daily and monthly rainfall grids. To derive the monthly estimates, rainfall totals from monthly and daily (when complete month available) rain gauges were used in order to obtain maximum information from the rain gauge network. The daily grids were adjusted so that the monthly grids are fully consistent with the daily grids. The CEH-GEAR data set was developed according to the guidance provided by the British Standards Institution. The CEH-GEAR data set contains 1 km grids of daily and monthly rainfall estimates for GB and NI for the period 1890-2012. For each day and month, CEH-GEAR includes a secondary grid of distance to the nearest operational rain gauge. This may be used as an indicator of the quality of the estimates. When this distance is greater than 100 km, the estimates are not calculated due to high uncertainty. CEH-GEAR is available from doi:10.5285/5dc179dc-f692-49ba-9326-a6893a503f6e and is free of charge for commercial and non-commercial use subject to licensing terms and conditions.

  8. High-Resolution Satellite-Derived PM2.5 from Optimal Estimation and Geographically Weighted Regression over North America.

    PubMed

    van Donkelaar, Aaron; Martin, Randall V; Spurr, Robert J D; Burnett, Richard T

    2015-09-01

    We used a geographically weighted regression (GWR) statistical model to represent bias of fine particulate matter concentrations (PM2.5) derived from a 1 km optimal estimate (OE) aerosol optical depth (AOD) satellite retrieval that used AOD-to-PM2.5 relationships from a chemical transport model (CTM) for 2004-2008 over North America. This hybrid approach combined the geophysical understanding and global applicability intrinsic to the CTM relationships with the knowledge provided by observational constraints. Adjusting the OE PM2.5 estimates according to the GWR-predicted bias yielded significant improvement compared with unadjusted long-term mean values (R(2) = 0.82 versus R(2) = 0.62), even when a large fraction (70%) of sites were withheld for cross-validation (R(2) = 0.78) and developed seasonal skill (R(2) = 0.62-0.89). The effect of individual GWR predictors on OE PM2.5 estimates additionally provided insight into the sources of uncertainty for global satellite-derived PM2.5 estimates. These predictor-driven effects imply that local variability in surface elevation and urban emissions are important sources of uncertainty in geophysical calculations of the AOD-to-PM2.5 relationship used in satellite-derived PM2.5 estimates over North America, and potentially worldwide.

  9. Estimation of surface soil moisture in alpine areas based on medium spatial resolution SAR time-series and upscaled in-situ measurements

    NASA Astrophysics Data System (ADS)

    Greifeneder, F.; Notarnicola, C.; Cuozzo, G.; Bertoldi, G.; Della Chiesa, S.; Niedrist, G.; Stamenkovic, J.; Wagner, W.

    2014-10-01

    The goal of this study was to assess the applicability of medium resolution SAR time-series, in combination with in-situ point measurements and machine learning, for the estimation of soil moisture content (SMC). One of the main challenges was the combination of SMC point measurements and satellite data. Due to the high spatial variability of soil moisture a direct linkage can be inappropriate. Data used in this study were a combination of in-situ data, satellite data and modelled SMC from the hydrological model GEOtop. To relate the point measurements with the satellite pixel footprint resolution, a spatial upscaling method was developed. It was found that both temporal and spatial SMC patterns obtained from various data sources (ASAR WS, GEOtop and meteorological stations) show similar behaviors. Furthermore, it was possible to increase the absolute accuracy of the estimated SMC through spatial upscaling of the obtained in-situ data. Introducing information on the temporal behavior of the SAR signal proves to be a promising method to increase the confidence and accuracy of SMC estimations. Following steps were identified as critical for the retrieval process: the topographic correction and geocoding of SAR data, the calibration of the meteorological stations and the spatial upscaling.

  10. Estimation of mineral dust direct radiative forcing at the European Aerosol Research Lidar NETwork site of Lecce, Italy, during the ChArMEx/ADRIMED summer 2013 campaign: Impact of radiative transfer model spectral resolutions

    NASA Astrophysics Data System (ADS)

    Barragan, Ruben; Romano, Salvatore; Sicard, Michaël.; Burlizzi, Pasquale; Perrone, Maria Rita; Comeron, Adolfo

    2016-09-01

    A field campaign took place in the western and central Mediterranean basin on June-July 2013 in the framework of the ChArMEx (Chemistry-Aerosol Mediterranean Experiment, http://charmex.lsce.ipsl.fr/)/ADRIMED (Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region, http://adrimed.sedoo.fr/) project to characterize the aerosol direct radiative forcing (DRF) over the Mediterranean. This work focuses on the aerosol DRF estimations at Lecce (40.33°N; 18.11°E; 30 m above sea level) during the Saharan dust outbreak that affected southern Italy from 20 to 24 June 2013. The Global Atmospheric Model (GAME) and the Two-Stream (TS) model were used to calculate the instantaneous aerosol DRF in the short-wave (SW) and long-wave (LW) spectral ranges, at the surface and at the top of the atmosphere (TOA). The main differences between the two models were due to the different numerical methods to solve the radiative transfer (RT) equations and to the more detailed spectral resolution of GAME compared to that of TS. 167 and 115 subbands were used by GAME in the 0.3-4 and 4-37 µm spectral ranges, respectively. Conversely, the TS model used 8 and 11 subbands in the same spectral ranges, respectively. We found on 22 June that the SW-DRFs from the two models were in good agreement, both at the TOA and at the surface. The instantaneous SW-DRFs at the surface and at the TOA varied from -50 to -34 W m-2 and from -6 to +8 W m-2, respectively, while the surface and TOA LW-DRFs ranged between +3.5 and +8.0 W m-2 and between +1.7 and +6.9 W m-2, respectively. In particular, both models provided positive TOA SW-DRFs at solar zenith angles smaller than 25° because of the mixing of the desert dust with anthropogenic pollution during its transport to the study site. In contrast, the TS model overestimated the GAME LW-DRF up to about 5 and 7.5 times at the surface and at the TOA, respectively, when the dust particle contribution was largest. The low spectral

  11. Application of advanced very high resolution radiometer (AVHRR)-based vegetation health indices for estimation of malaria cases.

    PubMed

    Rahman, Atiqur; Krakauer, Nir; Roytman, Leonid; Goldberg, Mitch; Kogan, Felix

    2010-06-01

    Satellite data may be used to map climatic conditions conducive to malaria outbreaks, assisting in the targeting of public health interventions to mitigate the worldwide increase in incidence of the mosquito-transmitted disease. This work analyzes correlation between malaria cases and vegetation health (VH) indices derived from satellite remote sensing for each week over a period of 14 years for Bandarban, Bangladesh. Correlation analysis showed that years with a high summer temperature condition index (TCI) tended to be those with high malaria incidence. Principal components regression was performed on patterns of weekly TCI during each of the two annual malaria seasons to construct a model as a function of the TCI. These models reduced the malaria estimation error variance by 57% if first-peak (June-July) TCI was used as the estimator and 74% if second-peak (August-September) was used, compared with an estimation of average number of malaria cases for each year.

  12. MeSiC: A Model-Based Method for Estimating 5 mC Levels at Single-CpG Resolution from MeDIP-seq.

    PubMed

    Xiao, Yun; Yu, Fulong; Pang, Lin; Zhao, Hongying; Liu, Ling; Zhang, Guanxiong; Liu, Tingting; Zhang, Hongyi; Fan, Huihui; Zhang, Yan; Pang, Bo; Li, Xia

    2015-10-01

    As the fifth base in mammalian genome, 5-methylcytosine (5 mC) is essential for many biological processes including normal development and disease. Methylated DNA immunoprecipitation sequencing (MeDIP-seq), which uses anti-5 mC antibodies to enrich for methylated fraction of the genome, is widely used to investigate methylome at a resolution of 100-500 bp. Considering the CpG density-dependent bias and limited resolution of MeDIP-seq, we developed a Random Forest Regression (RFR) model method, MeSiC, to estimate DNA methylation levels at single-base resolution. MeSiC integrated MeDIP-seq signals of CpG sites and their surrounding neighbors as well as genomic features to construct genomic element-dependent RFR models. In the H1 cell line, a high correlation was observed between MeSiC predictions and actual 5 mC levels. Meanwhile, MeSiC enabled to calibrate CpG density-dependent bias of MeDIP-seq signals. Importantly, we found that MeSiC models constructed in the H1 cell line could be used to accurately predict DNA methylation levels for other cell types. Comparisons with methylCRF and MEDIPS showed that MeSiC achieved comparable and even better performance. These demonstrate that MeSiC can provide accurate estimations of 5 mC levels at single-CpG resolution using MeDIP-seq data alone.

  13. Targeting Nitrous Oxide Reduction Efforts Using Crop-Specific, High-Resolution Emission Estimates from Synthetic Fertilizer

    NASA Astrophysics Data System (ADS)

    Gerber, J. S.; West, P. C.; Carlson, K. M.; Garcia de Cortazar-Atauri, I.; Launay, M.; Makowski, D.; Mueller, N. D.; O'Connell, C.

    2014-12-01

    Changes in global weather patterns are projected to have important impacts on regional food security. These impacts can be substantial, but how do they compare to other drivers of food supply vulnerability, including decreasing stocks, changing trade patterns, concentration of production, and changing demand patterns? We use multi-year global datasets of yield and area for staple crops to assess relationships between metrics of drought derived from high-resolution gridded weather data and crop yields. We then evaluate how these metrics are changing over time, and compare the resulting change in the likelihood of regional yield reduction events to other systemic factors.

  14. High-resolution estimates of Nubia-Somalia plate motion since 20 Ma from reconstructions of the Southwest Indian Ridge, Red Sea, and Gulf of Aden

    NASA Astrophysics Data System (ADS)

    DeMets, C.; Merkuryev, S. A.

    2015-12-01

    We estimate Nubia-Somalia rotations at ~1-Myr intervals for the past 20 Myr from newly available, high-resolution reconstructions of the Southwest Indian Ridge and reconstructions of the Red Sea and Gulf of Aden. The former rotations are based on many more data, extend farther back in time, and have more temporal resolution than has previously been the case. Nubia-Somalia plate motion has remained remarkably steady since 5.2 Ma. For example, at the northern end of the East Africa rift, our Nubia-Somalia plate motion estimates at six different times between 0.78 Ma and 5.2 Ma agree to within 3% with the rift-normal component of motion that is extrapolated from the recently estimated Saria et al. (2014) GPS angular velocity. Over the past 10.6 Myr, the Nubia-Somalia rotations predict 42±4 km of rift-normal extension across the northern segment of the Main Ethiopian Rift. This agrees with approximate minimum and maximum estimates of 40 km and 53 km for post-10.6-Myr extension from seismological surveys of this narrow part of the plate boundary and is also close to 55-km and 48±3 km estimates from published and our own reconstructions of the Nubia-Arabia and Somalia-Arabia seafloorspreading histories for the Red Sea and Gulf of Aden. Our new rotations exclude at high confidence level two previously published estimates of Nubia-Somalia motion based on inversions of Chron 5n.2 along the Southwest Indian Ridge, which predict rift-normal extensions of 13±14 km and 129±16 km across the Main Ethiopian Rift since 11 Ma. Constraints on Nubia-Somalia motion before ~15 Ma are weaker due to sparse coverage of pre-15-Myr magnetic reversals along the Nubia-Antarctic plate boundary, but appear to require motion before 15 Ma. Nubia-Somalia rotations that we estimate from a probabilistic analysis of geometric and age constraints from the Red Sea and Gulf of Aden are consistent with those determined from Southwest Indian Ridge data, particularly for the past 11 Myr. Nubia

  15. A comparison of methods for estimating climate change impact on design rainfall using a high-resolution RCM

    NASA Astrophysics Data System (ADS)

    Li, Jingwan; Evans, Jason; Johnson, Fiona; Sharma, Ashish

    2017-04-01

    Design rainfall is used to analyse and size water infrastructure and is generally derived from historical rainfall records. Given the expected changes in extreme rainfall due to anthropogenic climate change, future hydrologic design based on historical data may not be appropriate. While a number of studies have assessed the impact of climate change on design rainfall using different methods, to date there has been no comprehensive comparison or examination of the implications of alternative methods on future design rainfall estimates. This study compares the nine methods for estimating the design rainfall for the current climate and the potential changes in the future for the Greater Sydney region. A Monte Carlo cross-validation procedure was employed to evaluate the skill of each method in estimating the design rainfall for the current climate. It was found that bias correcting the annual maximum rainfall based on the empirical distribution combined with regional frequency analysis produces the design rainfall closest to the observations. While regional frequency analysis was found to have limited impact on the design rainfall estimation for the current climate, it provides much more spatially coherent patterns of future change and it is recommended that regionalisation be used in all design rainfall impact assessments. Despite the variations between different methods, a 20-35% increase in design rainfall over the coastal region is consistently projected. This will pose significant challenges for existing infrastructure in that area.

  16. Millimetre observations of comets P/Brorsen-Metcalf (1989o) and Austin (1989c1) with the IRAM 30-m radio telescope

    NASA Technical Reports Server (NTRS)

    Colom, P.; Despois, D.; Bockelee-Morvan, D.; Crovisier, J.; Paubert, G.

    1990-01-01

    Millimeter observations with the IRAM 30 m telescope were conducted in comet P/Brorsen-Metcalf (1989o) on September 1989 and Austin (1989c1) on April and May 1990. The HCN J(1-0) and J(3-2) lines were detected in both comets. The HCN production rate relative to water in P/Brorsen-Metcalf is comparable to that previously measured in comet P/Halley, while that inferred in comet Austin might be smaller by a factor of two. The H2CO(3 sub 12 - 2 sub 11) transition, marginally observed in comet P/Brorsen-Metcalf, was firmly detected in May 1990 in comet Austin. Observations performed at offset positions suggest that the source of H2CO might be distributed. The H2CO abundance is on the order of 0.5 percent that of water for both comets, assuming a scalelength of 10(exp 4) km at 1 AU from the Sun for the distributed source. During the May observing period of comet Austin, two new species were detected for the first time in a comet: hydrogen sulfide (H2S) through its 1(sub 10) - 1(sub 01) ortho line at 169 GHz, and methanol (CH3OH) through J(3-2) delta K = 0 transitions at 145 GHz. Preliminary estimates of their abundances are 1.5 x 10(exp -3) for H2S and 8 x 10(exp -3) for CH3OH.

  17. Estimating biomass, yield, evaprotranspiration and carbon fluxes for winter wheat by using high resolution remote sensing data combined with a crop model

    NASA Astrophysics Data System (ADS)

    Veloso, A.; Ceschia, E.; Demarez, V.

    2013-12-01

    The use of crop models allows simulating plant development, growth, yield, CO2 and water fluxes under different environmental and management conditions. When combined with high spatial and temporal resolution remote sensing data, these models provide new perspectives for crop monitoring at regional scale. Besides, monitoring spatial and temporal variation in water budget and amount of carbon fixed by these crops is an ultimate goal of earth climate change studies. We propose here an approach to estimate time courses of dry aboveground biomass (DAM), yield and evapotranspiration (ETR) for winter wheat by assimilating Green Area Index (GAI) data, obtained from satellite observations, into a simple crop model. This model is then coupled with a ';carbon flux module' for estimating the components of the carbon budget (gross primary production (GPP), ecosystem respiration (Reco), ...). Among the several land surface biophysical variables accessible from satellite observations, the GAI is the one that has a key role in soil-plant-atmosphere interactions and in biomass accumulation process. Many methods have been developed to relate GAI to optical remote sensing signal. Here, seasonal dynamics of remotely sensed GAI were estimated by applying a method based on the inversion of a radiative transfer model using artificial neural networks. For this work, we employed a unique set of Formosat-2 and SPOT images acquired from 2006 to 2011 in southwest France. The modelling approach is based on the Simple Algorithm for Yield and Evapotranspiration estimate (SAFYE) model, which couples the FAO-56 model with an agro-meteorological model, based on Monteith's light-use efficiency theory. The SAFYE model is a daily time step crop model that simulates time series of GAI, biomass (NPP), grain yield and ETR. The carbon flux module simulates GPP, the autotrophic respiration (Ra) that is defined as the sum of plant growth and maintenance respiration and the heterotrophic respiration (Rh

  18. High Resolution Rutherford Back Scattering Estimation of the Surface Implanted Nitrogen Ion by Using Plasma-based Ion Implantation

    NASA Astrophysics Data System (ADS)

    Tanaka, Takeshi; Takagi, Toshinori

    Plasma-based ion implantation (PBII) with negative voltage pulses to the test specimen has been applied to the sterilization process as a technique suitable for three-dimensional work pieces. Pulsed high negative voltage (5 μs pulse width, 300 pulses/s, -800 V to -15 kV) was applied to the electrode in this process at a gas pressure of 2.4 Pa of N2. We found that the PBII process, in which (N2 gas self-ignitted plasma generated by only pulsed voltages is used) reduces the numbers of active Bacillus pumilus cell. The number of bacteria survivors was reduced by 10-5 x with 5 min exposure. As the ion energy is one of the important processing parameters on sterilization of the surface, the ion energy is discussed from the high resolution RBS depth profile.

  19. The IRAM-30 m line survey of the Horsehead PDR. IV. Comparative chemistry of H2CO and CH3OH

    NASA Astrophysics Data System (ADS)

    Guzmán, V. V.; Goicoechea, J. R.; Pety, J.; Gratier, P.; Gerin, M.; Roueff, E.; Le Petit, F.; Le Bourlot, J.; Faure, A.

    2013-12-01

    Context. Theoretical models and laboratory experiments show that CH3OH is efficiently formed on cold grain surfaces through the successive hydrogenation of CO, forming HCO and H2CO as intermediate species. In cold cores and low UV-field illumination photo-dissociation regions (PDRs) the ices can be released into the gas-phase through nonthermal processes such as photodesorption, which considerably increases their gas-phase abundances. Aims: We investigate the dominant formation mechanism of H2CO and CH3OH in the Horsehead PDR and its associated dense core. Methods: We performed deep integrations of several H2CO and CH3OH lines at two positions in the Horsehead, namely the PDR and dense core, with the IRAM-30 m telescope. In addition, we observed one H2CO higher-frequency line with the CSO telescope at both positions. We determined the H2CO and CH3OH column densities and abundances from the single-dish observations complemented with IRAM-PdBI high-angular resolution maps (6'') of both species. We compared the observed abundances with PDR models including either pure gas-phase chemistry or both gas-phase and grain surface chemistry. Results: We derived CH3OH abundances relative to total number of hydrogen atoms of ~1.2 × 10-10 and ~2.3 × 10-10 in the PDR and dense-core positions, respectively. These abundances are similar to the inferred H2CO abundance in both positions (~2 × 10-10). We find an abundance ratio H2CO/CH3OH of ~2 in the PDR and ~1 in the dense core. Pure gas-phase models cannot reproduce the observed abundances of either H2CO or CH3OH at the PDR position. The two species are therefore formed on the surface of dust grains and are subsequently photodesorbed into the gas-phase at this position. At the dense core, on the other hand, photodesorption of ices is needed to explain the observed abundance of CH3OH, while a pure gas-phase model can reproduce the observed H2CO abundance. The high-resolution observations show that CH3OH is depleted onto grains at

  20. The Impact of the Processing Batch Length in GNSS Data Analysis on the Estimates of Earth Rotation Parameters with Daily and Subdaily Time Resolution

    NASA Astrophysics Data System (ADS)

    Meindl, M.; Dach, R.; Thaller, D.; Schaer, S.; Beutler, G.; Jaeggi, A.

    2012-04-01

    Microwave observations from GNSS are traditionally analyzed in the post-processing mode using (solar) daily data batches. The 24-hour session length differs by only about four minutes from two revolution periods of a GPS satellite (corresponding to one sidereal day). The deep 2:1 resonance of the GPS revolution period with the length of the sidereal day may cause systematic effects in parameter estimates and spurious periodic signals in the resulting parameter time series. The selection of other (than daily) session lengths may help to identify systematic effects and to study their impact on GNSS-derived products. Such investigations are of great interest in a combined multi-GNSS analysis because of substantial differences in the satellites' revolution periods. Three years (2008-2010) of data from a global network of about 90 combined GPS/GLONASS receivers have been analyzed. Four different session lengths were used, namely the traditional 24 hours (UTC), two revolutions of a GLONASS satellite (16/17 sidereal days), two revolutions of a GPS satellite (one sidereal day), and a session length of 18/17 sidereal days, which does not correspond to either two GPS or two GLONASS revolution periods. GPS-only, GLONASS-only, and GPS/GLONASS-combined solution are established for each of the session lengths. Special care was taken to keep the GPS and GLONASS solutions fully consistent and comparable in particular where the station selection is concerned. We generate ERPs with a subdaily time resolution of about 1.4 hours (1/17 sidereal day). Using the session-specific normal equation systems (NEQs) containing the Earth rotation parameters with the 1.4 hours time resolution we derive in addition ERPs with a (sidereal) daily resolution. Note that this step requires the combination of the daily NEQs and a subsequent re-binning of 17 consecutive ERPs with 1/17 day time resolution into one (sidereal) daily parameter. These tests will reveal the impact of the session length on ERP

  1. A New Hybrid Spatio-temporal Model for Estimating Daily Multi-year PM2.5 Concentrations Across Northeastern USA Using High Resolution Aerosol Optical Depth Data

    NASA Technical Reports Server (NTRS)

    Kloog, Itai; Chudnovsky, Alexandra A.; Just, Allan C.; Nordio, Francesco; Koutrakis, Petros; Coull, Brent A.; Lyapustin, Alexei; Wang, Yujie; Schwartz, Joel

    2014-01-01

    The use of satellite-based aerosol optical depth (AOD) to estimate fine particulate matter PM(sub 2.5) for epidemiology studies has increased substantially over the past few years. These recent studies often report moderate predictive power, which can generate downward bias in effect estimates. In addition, AOD measurements have only moderate spatial resolution, and have substantial missing data. We make use of recent advances in MODIS satellite data processing algorithms (Multi-Angle Implementation of Atmospheric Correction (MAIAC), which allow us to use 1 km (versus currently available 10 km) resolution AOD data.We developed and cross validated models to predict daily PM(sub 2.5) at a 1X 1 km resolution across the northeastern USA (New England, New York and New Jersey) for the years 2003-2011, allowing us to better differentiate daily and long term exposure between urban, suburban, and rural areas. Additionally, we developed an approach that allows us to generate daily high-resolution 200 m localized predictions representing deviations from the area 1 X 1 km grid predictions. We used mixed models regressing PM(sub 2.5) measurements against day-specific random intercepts, and fixed and random AOD and temperature slopes. We then use generalized additive mixed models with spatial smoothing to generate grid cell predictions when AOD was missing. Finally, to get 200 m localized predictions, we regressed the residuals from the final model for each monitor against the local spatial and temporal variables at each monitoring site. Our model performance was excellent (mean out-of-sample R(sup 2) = 0.88). The spatial and temporal components of the out-of-sample results also presented very good fits to the withheld data (R(sup 2) = 0.87, R(sup)2 = 0.87). In addition, our results revealed very little bias in the predicted concentrations (Slope of predictions versus withheld observations = 0.99). Our daily model results show high predictive accuracy at high spatial resolutions

  2. Assessment of Intensity-Duration-Frequency curves for the Eastern Mediterranean region derived from high-resolution satellite and radar rainfall estimates

    NASA Astrophysics Data System (ADS)

    Marra, Francesco; Morin, Efrat; Peleg, Nadav; Mei, Yiwen; Anagnostou, Emmanouil N.

    2016-04-01

    Intensity-duration-frequency (IDF) curves are used in flood risk management and hydrological design studies to relate the characteristics of a rainfall event to the probability of its occurrence. The usual approach relies on long records of raingauge data providing accurate estimates of the IDF curves for a specific location, but whose representativeness decreases with distance. Radar rainfall estimates have recently been tested over the Eastern Mediterranean area, characterized by steep climatological gradients, showing that radar IDF curves generally lay within the raingauge confidence interval and that radar is able to identify the climatology of extremes. Recent availability of relatively long records (>15 years) of high resolution satellite rainfall information allows to explore the spatial distribution of extreme rainfall with increased detail over wide areas, thus providing new perspectives for the study of precipitation regimes and promising both practical and theoretical implications. This study aims to (i) identify IDF curves obtained from radar rainfall estimates and (ii) identify and assess IDF curves obtained from two high resolution satellite retrieval algorithms (CMORPH and PERSIANN) over the Eastern Mediterranean region. To do so, we derive IDF curves fitting a GEV distribution to the annual maxima series from 23 years (1990-2013) of carefully corrected data from a C-Band radar located in Israel (covering Mediterranean to arid climates) as well as from 15 years (1998-2014) of gauge-adjusted high-resolution CMORPH and 10 years (2003-2013) of gauge-adjusted high-resolution PERSIANN data. We present the obtained IDF curves and we compare the curves obtained from the satellite algorithms to the ones obtained from the radar during overlapping periods; this analysis will draw conclusions on the reliability of the two satellite datasets for deriving rainfall frequency analysis over the region and provide IDF corrections. We compare then the curves obtained

  3. 10 Yr Spatial and Temporal Trends of PM2.5 Concentrations in the Southeastern US Estimated Using High-resolution Satellite Data

    NASA Technical Reports Server (NTRS)

    Hu, X.; Waller, L. A.; Lyapustin, A.; Wang, Y.; Liu, Y.

    2013-01-01

    Long-term PM2.5 exposure has been reported to be associated with various adverse health outcomes. However, most ground monitors are located in urban areas, leading to a potentially biased representation of the true regional PM2.5 levels. To facilitate epidemiological studies, accurate estimates of spatiotemporally continuous distribution of PM2.5 concentrations are essential. Satellite-retrieved aerosol optical depth (AOD) has been widely used for PM2.5 concentration estimation due to its comprehensive spatial coverage. Nevertheless, an inherent disadvantage of current AOD products is their coarse spatial resolutions. For instance, the spatial resolutions of the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Multiangle Imaging SpectroRadiometer (MISR) are 10 km and 17.6 km, respectively. In this paper, a new AOD product with 1 km spatial resolution retrieved by the multi-angle implementation of atmospheric correction (MAIAC) algorithm was used. A two-stage model was developed to account for both spatial and temporal variability in the PM2.5-AOD relationship by incorporating the MAIAC AOD, meteorological fields, and land use variables as predictors. Our study area is in the southeastern US, centered at the Atlanta Metro area, and data from 2001 to 2010 were collected from various sources. The model was fitted for each year individually, and we obtained model fitting R2 ranging from 0.71 to 0.85, MPE from 1.73 to 2.50 g m3, and RMSPE from 2.75 to 4.10 g m3. In addition, we found cross validation R2 ranging from 0.62 to 0.78, MPE from 2.00 to 3.01 g m3, and RMSPE from 3.12 to 5.00 g m3, indicating a good agreement between the estimated and observed values. Spatial trends show that high PM2.5 levels occurred in urban areas and along major highways, while low concentrations appeared in rural or mountainous areas. A time series analysis was conducted to examine temporal trends of PM2.5 concentrations in the study area from 2001 to 2010. The results showed

  4. Implications of uncertainty on regional CO2 mitigation policies for the U.S. onroad sector based on a high-resolution emissions estimate

    SciTech Connect

    Mendoza, D.; Gurney, Kevin R.; Geethakumar, Sarath; Chandrasekaran, Vandhana; Zhou, Yuyu; Razlivanov, I.

    2013-04-01

    In this study we present onroad fossil fuel CO2 emissions estimated by the Vulcan Project, an effort quantifying fossil fuel CO2 emissions for the U.S. in high spatial and temporal resolution. This high-resolution data, aggregated at the state-level and classified in broad road and vehicle type categories, is compared to a commonly used national-average approach. We find that the use of national averages incurs state-level biases for road groupings that are almost twice as large as for vehicle groupings. The uncertainty for all groups exceeds the bias, and both quantities are positively correlated with total state emissions. States with the largest emissions totals are typically similar to one another in terms of emissions fraction distribution across road and vehicle groups, while smaller-emitting states have a wider range of variation in all groups. Errors in reduction estimates as large as ±60% corresponding to ±0.2 MtC are found for a national-average emissions mitigation strategy focused on a 10% emissions reduction from a single vehicle class, such as passenger gas vehicles or heavy diesel trucks. Recommendations are made for reducing CO2 emissions uncertainty by addressing its main drivers: VMT and fuel efficiency uncertainty.

  5. Estimation of PSD Shifts for High-Resolution Metrology of Thickness Micro-Changes with Possible Applications in Vessel Walls and Biological Membrane Characterization

    PubMed Central

    Ramos, Antonio; Bazán, Ivonne; Negreira, Carlos; Brum, Javier; Gómez, Tomás; Calás, Héctor; Ruiz, Abelardo; de la Rosa, José Manuel

    2012-01-01

    Achieving accurate measurements of inflammation levels in tissues or thickness changes in biological membranes (e.g., amniotic sac, parietal pleura) and thin biological walls (e.g., blood vessels) from outside the human body, is a promising research line in the medical area. It would provide a technical basis to study the options for early diagnosis of some serious diseases such as hypertension, atherosclerosis or tuberculosis. Nevertheless, achieving the aim of non-invasive measurement of those scarcely-accessible parameters on patient internal tissues, currently presents many difficulties. The use of high-frequency ultrasonic transducer systems appears to offer a possible solution. Previous studies using conventional ultrasonic imaging have shown this, but the spatial resolution was not sufficient so as to permit a thickness evaluation with clinical significance, which requires an accuracy of a few microns. In this paper a broadband ultrasonic technique, that was recently developed by the authors to address other non-invasive medical detection problems (by integrating a piezoelectric transducer into a spectral measuring system), is extended to our new objective; the aim is its application to the thickness measurement of sub-millimeter membranes or layers made of materials similar to some biological tissues (phantoms). The modeling and design rules of such a transducer system are described, and various methods of estimating overtones location in the power spectral density (PSD) are quantitatively assessed with transducer signals acquired using piezoelectric systems and also generated from a multi-echo model. Their effects on the potential resolution of the proposed thickness measuring tool, and their capability to provide accuracies around the micron are studied in detail. Comparisons are made with typical tools for extracting spatial parameters in laminar samples from echo-waveforms acquired with ultrasonic transducers. Results of this advanced measurement

  6. High-resolution estimates of Nubia-Somalia plate motion since 20 Ma from reconstructions of the Southwest Indian Ridge, Red Sea and Gulf of Aden

    NASA Astrophysics Data System (ADS)

    DeMets, C.; Merkouriev, S.

    2016-10-01

    Large gaps and inconsistencies remain in published estimates of Nubia-Somalia plate motion based on reconstructions of seafloor spreading data around Africa. Herein, we use newly available reconstructions of the Southwest Indian Ridge at ˜1-Myr intervals since 20 Ma to estimate Nubia-Somalia plate motion farther back in time than previously achieved and with an unprecedented degree of temporal resolution. At the northern end of the East African rift, our new estimates of Nubia-Somalia motion for six times from 0.78 Ma to 5.2 Ma differ by only 2 per cent from the rift-normal component of motion that is extrapolated from a recently estimated GPS angular velocity. The rate of rift-normal extension thus appears to have remained steady since at least 5.2 Ma. Our new rotations indicate that the two plates have moved relative to each other since at least 16 Ma and possibly longer. Motion has either been steady since at least 16 Ma or accelerated modestly between 6 and 5.2 Ma. Our Nubia-Somalia rotations predict 42.5 ± 3.8 km of rift-normal extension since 10.6 Ma across the well-studied, northern segment of the Main Ethiopian Rift, consistent with 40-50 km estimates for extension since 10.6 Myr based on seismological surveys of this narrow part of the plate boundary. Nubia-Somalia rotations are also derived by combining newly estimated Somalia-Arabia rotations that reconstruct the post-20-Ma opening of the Gulf of Aden with Nubia-Arabia rotations estimated via a probabilistic analysis of plausible opening scenarios for the Red Sea. These rotations predict Nubia-Somalia motion since 5.2 Myr that is consistent with that determined from Southwest Indian Ridge data and also predict 40 ± 3 km of rift-normal extension since 10.6 Ma across the Main Ethiopian Rift, consistent with our 42.5 ± 3.8 km Southwest Indian Ridge estimate. Our new rotations exclude at high confidence level previous estimates of 12 ± 13 and 123 ± 14 km for rift-normal extensions across the Main

  7. Nano silver and nano zinc-oxide in surface waters - exposure estimation for Europe at high spatial and temporal resolution.

    PubMed

    Dumont, Egon; Johnson, Andrew C; Keller, Virginie D J; Williams, Richard J

    2015-01-01

    Nano silver and nano zinc-oxide monthly concentrations in surface waters across Europe were modeled at ~6 x 9 km spatial resolution. Nano-particle loadings from households to rivers were simulated considering household connectivity to sewerage, sewage treatment efficiency, the spatial distribution of sewage treatment plants, and their associated populations. These loadings were used to model temporally varying nano-particle concentrations in rivers, lakes and wetlands by considering dilution, downstream transport, water evaporation, water abstraction, and nano-particle sedimentation. Temporal variability in concentrations caused by weather variation was simulated using monthly weather data for a representative 31-year period. Modeled concentrations represent current levels of nano-particle production.Two scenarios were modeled. In the most likely scenario, half the river stretches had long-term average concentrations exceeding 0.002 ng L(-1) nano silver and 1.5 ng L(-1) nano zinc oxide. In 10% of the river stretches, these concentrations exceeded 0.18 ng L(-1) and 150 ng L(-1), respectively. Predicted concentrations were usually highest in July.

  8. Evaluation of High-Resolution Precipitation Estimates from Satellites during July 2012 Beijing Flood Event Using Dense Rain Gauge Observations

    PubMed Central

    Chen, Sheng; Liu, Huijuan; You, Yalei; Mullens, Esther; Hu, Junjun; Yuan, Ye; Huang, Mengyu; He, Li; Luo, Yongming; Zeng, Xingji; Tang, Guoqiang; Hong, Yang

    2014-01-01

    Satellite-based precipitation estimates products, CMORPH and PERSIANN-CCS, were evaluated with a dense rain gauge network over Beijing and adjacent regions for an extremely heavy precipitation event on July 21 2012. CMORPH and PEERSIANN-CSS misplaced the region of greatest rainfall accumulation, and failed to capture the spatial pattern of precipitation, evidenced by a low spatial correlation coefficient (CC). CMORPH overestimated the daily accumulated rainfall by 22.84% while PERSIANN-CCS underestimated by 72.75%. In the rainfall center, both CMORPH and PERSIANN-CCS failed to capture the temporal variation of the rainfall, and underestimated rainfall amounts by 43.43% and 87.26%, respectively. Based on our results, caution should be exercised when using CMORPH and PERSIANN-CCS as input for monitoring and forecasting floods in Beijing urban areas, and the potential for landslides in the mountainous zones west and north of Beijing. PMID:24691358

  9. An objective technique to estimate percentage of an ERTS-1 water boundary resolution element covered by water

    NASA Technical Reports Server (NTRS)

    Erb, R. B. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. An objective technique was developed to measure the surface area of water bodies. Nineteen water bodies in the Houston and Galveston, Texas area were selected as a basis for the technique development. The actual surface area of each body was determined from rectified and enlarged NASA aircraft photography. A clustering algorithm was used to produce classification maps of the region from ERTS-1 data. Certain classes were identified as being 100% water. Other classes were identified as being mixtures of water with land or vegetation. The number of picture elements falling on each water body and its boundary were counted. A linear regression analysis was performed to relate the total number of picture elements and boundary elements counted to the actual surface area. The standard error of the estimate was 6.7 acres. The absolute error was not a function of the actual surface area of the water body.

  10. Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)

    NASA Astrophysics Data System (ADS)

    Belloche, A.; Müller, H. S. P.; Menten, K. M.; Schilke, P.; Comito, C.

    2013-11-01

    Context. The discovery of amino acids in meteorites fallen to Earth and the detection of glycine, the simplest of them, in samples returned from a comet to Earth strongly suggest that the chemistry of the interstellar medium is capable of producing such complex organic molecules and that they may be widespread in our Galaxy. Aims: Our goal is to investigate the degree of chemical complexity that can be reached in the interstellar medium, in particular in dense star-forming regions. Methods: We performed an unbiased, spectral line survey toward Sgr B2(N) and (M), two regions where high-mass stars are formed, with the IRAM 30 m telescope in the 3 mm atmospheric transmission window. Partial surveys at 2 and 1.3 mm were performed in parallel. The spectra were analyzed with a simple radiative transfer model that assumes local thermodynamic equilibrium but takes optical depth effects into account. Results: About 3675 and 945 spectral lines with a peak signal-to-noise ratio higher than 4 are detected at 3 mm toward Sgr B2(N) and (M), i.e. about 102 and 26 lines per GHz, respectively. This represents an increase by about a factor of two over previous surveys of Sgr B2. About 70% and 47% of the lines detected toward Sgr B2(N) and (M) are identified and assigned to 56 and 46 distinct molecules as well as to 66 and 54 less abundant isotopologues of these molecules, respectively. In addition, we report the detection of transitions from 59 and 24 catalog entries corresponding to vibrationally or torsionally excited states of some of these molecules, respectively, up to a vibration energy of 1400 cm-1 (2000 K). Excitation temperatures and column densities were derived for each species but should be used with caution. The rotation temperatures of the detected complex molecules typically range from ~50 to 200 K. Among the detected molecules, aminoacetonitrile, n-propyl cyanide, and ethyl formate were reported for the first time in space based on this survey, as were five rare

  11. Instrument Performance of GISMO, a 2 Millimeter TES Bolometer Camera used at the IRAM 30 m Telescope

    NASA Technical Reports Server (NTRS)

    Staguhn, Johannes

    2008-01-01

    In November of 2007 we demonstrated a monolithic Backshort-Under-Grid (BUG) 8x16 array in the field using our 2 mm wavelength imager GISMO (Goddard IRAM Superconducting 2 Millimeter Observer) at the IRAM 30 m telescope in Spain for astronomical observations. The 2 mm spectral range provides a unique terrestrial window enabling ground-based observations of the earliest active dusty galaxies in the universe and thereby allowing a better constraint on the star formation rate in these objects. The optical design incorporates a 100 mm diameter silicon lens cooled to 4 K, which provides the required fast beam yielding 0.9 lambda/D pixels. With this spatial sampling, GISMO will be very efficient at detecting sources serendipitously in large sky surveys, while the capability for diffraction limited imaging is preserved. The camera provides significantly greater detection sensitivity and mapping speed at this wavelength than has previously been possible. The instrument will fill in the spectral energy distribution of high redshift galaxies at the Rayleigh-Jeans part of the dust emission spectrum, even at the highest redshifts. Here1 will we present early results from our observing run with the first fielded BUG bolometer array. We have developed key technologies to enable highly versatile, kilopixel, infrared through millimeter wavelength bolometer arrays. The Backshort-Under-Grid (BUG) array consists of three components: 1) a transition-edge-sensor (TES) based bolometer array with background-limited sensitivity and high filling factor, 2) a quarter-wave reflective backshort grid providing high optical efficiency, and 3) a superconducting bump-bonded large format Superconducting Quantum Interference Device (SQUID) multiplexer readout. The array is described in more detail elsewhere (Allen et al., this conference). In November of 2007 we demonstrated a monolithic 8x 16 array with 2 mm-pitch detectors in the field using our 2 mm wavelength imager GISMO (Goddard IRAM

  12. Constraints on Flow Dynamics within the Oceanic Asthenosphere from a High-Resolution Estimate of Seismic Anisotropy

    NASA Astrophysics Data System (ADS)

    Gaherty, J. B.; Lin, P. Y.; Jin, G.; Collins, J. A.; Lizarralde, D.; Evans, R. L.; Hirth, G.; Mark, H. F.

    2015-12-01

    Convective flow in the mantle and the motions of tectonic plates produce deformation of the Earth's interior, and the rock fabric produced by this deformation can be discerned using anisotropy of seismic wavespeed. This deformation is particularly prevalent within the oceanic asthenosphere, including near seafloor-spreading centers as new plates are formed via corner flow, and within a weak asthenosphere that lubricates large-scale plate-driven flow and/or accommodates smaller-scale convection. Seismic models of oceanic upper mantle are conflicting regarding the relative importance of these deformation processes. Seafloor-spreading fabric is very strong just beneath the Moho at relatively local scales. At ocean-basin scales, the strongest fabric in the asthenosphere, and the relative importance of density-driven flow and plate-induced shear is ambiguous. Using Rayleigh waves recorded across the NoMelt ocean-bottom seismograph (OBS) array in the central Pacific, we provide a unique high-resolution constraint on seismic anisotropy within the oceanic lithosphere-asthenosphere system in the middle of a plate. Shear-velocity and conductivity profiles delineate a dry, high-velocity lid overlying a damp, weak asthenosphere. Azimuthal anisotropy is strongest within the lid, with fast direction coincident with seafloor spreading, consistent with Pn observations. Minimum azimuthal anisotropy occurs within the lowest-velocity (weakest) portion of the asthenosphere, and below which it increases to a secondary maximum. In no depth range does the fast direction correspond to apparent plate motion. The results suggest that the dominant deformation in the oceanic mantle occurs during corner flow at the ridge axis, and via pressure- and/or buoyancy-driven flow within the asthenosphere, possibly within a non-Newtonian low-viscosity channel. Shear associated with motion of the plate over the underlying asthenosphere, if present, is weak compared to these processes.

  13. Estimation of excess mortality due to long-term exposure to PM2.5 in Japan using a high-resolution model for present and future scenarios

    NASA Astrophysics Data System (ADS)

    Goto, Daisuke; Ueda, Kayo; Ng, Chris Fook Sheng; Takami, Akinori; Ariga, Toshinori; Matsuhashi, Keisuke; Nakajima, Teruyuki

    2016-09-01

    Particulate matter with a diameter of less than 2.5 μm, known as PM2.5, can affect human health, especially in elderly people. Because of the imminent aging of society in the near future in most developed countries, the human health impacts of PM2.5 must be evaluated. In this study, we used a global-to-regional atmospheric transport model to simulate PM2.5 in Japan with a high-resolution stretched grid system (∼10 km for the high-resolution model, HRM) for the present (the 2000) and the future (the 2030, as proposed by the Representative Concentrations Pathway 4.5, RCP4.5). We also used the same model with a low-resolution uniform grid system (∼100 km for the low-resolution model, LRM). These calculations were conducted by nudging meteorological fields obtained from an atmosphere-ocean coupled model and providing emission inventories used in the coupled model. After correcting for bias, we calculated the excess mortality due to long-term exposure to PM2.5 among the elderly (over 65 years old) based on different minimum PM2.5 concentration (MINPM) levels to account for uncertainty using the simulated PM2.5 distributions to express the health effect as a concentration-response function. As a result, we estimated the excess mortality for all of Japan to be 31,300 (95% confidence intervals: 20,700 to 42,600) people in 2000 and 28,600 (95% confidence intervals: 19,000 to 38,700) people in 2030 using the HRM with a MINPM of 5.8 μg/m3. In contrast, the LRM resulted in underestimates of approximately 30% (for PM2.5 concentrations in the 2000 and 2030), approximately 60% (excess mortality in the 2000) and approximately 90% (excess mortality in 2030) compared to the HRM results. We also found that the uncertainty in the MINPM value, especially for low PM2.5 concentrations in the future (2030) can cause large variability in the estimates, ranging from 0 (MINPM of 15 μg/m3 in both HRM and LRM) to 95,000 (MINPM of 0 μg/m3 in HRM) people.

  14. A high resolution estimate of the inorganic nitrogen flux from the Scheldt estuary to the coastal North Sea during a nitrogen-limited algal bloom, spring 1995

    SciTech Connect

    Regnier, P. |; Steefel, C.I.

    1999-05-01

    Massive short-term (4--8 wk) blooms of Phaeocystis have been observed in coastal North Sea waters in the spring for a number of years now. Researchers have shown that these algal blooms, which lead to eutrophication of the local water mass, are limited by the supply of inorganic nitrogen from the various bordering estuaries. The authors demonstrate using the case of a typical heavily polluted macrotidal estuary, the Scheldt in Belgium and the Netherlands, that the short duration of the algal blooms requires estuarine flux estimation methods with a high temporal resolution. They use the fully transient, multicomponent reactive transport model CONTRASTE to compute inorganic nitrogen fluxes through the mouth of the Scheldt estuary into the North Sea. The model simulations use a detailed dataset of upstream river discharges and solute concentrations along with tidal forcings for a 210 day period between December 1, 1994 and June 30, 1995. The temporally resolved estimate shows that widely used estuarine flux estimation methods which rely on a steady-state approximation underestimate the inorganic nitrogen loading available to sustain primary production in the North Sea during the period of the algal bloom by 100%.

  15. Ice sheet features identification, glacier velocity estimation, and glacier zones classification using high-resolution optical and SAR data

    NASA Astrophysics Data System (ADS)

    Thakur, Praveen K.; Dixit, Ankur; Chouksey, Arpit; Aggarwal, S. P.; Kumar, A. Senthil

    2016-05-01

    Ice sheet features, glacier velocity estimation and glacier zones or facies classification are important research activities highlighting the dynamics of ice sheets and glaciers in Polar Regions and in inland glaciers. The Cband inSAR data is of ERS 1/2 tandem pairs with one day interval for spring of 1996 and L-band PolinSAR data of ALOS-PALSAR-2 for spring of 2015 is used in glacier velocity estimation. Glacier classification is done using multi-temporal C-and L-band SAR data and also with single date full polarization and hybrid polarization data. In first part, a mean displacement of 9 cm day-1 was recorded using SAR interferometric technique using ERS 1/2 tandem data of 25-26 March 1996. Previous studies using optical data based methods has shown that Gangotri glacier moves with an average displacement of 4 cm and 6 cm day-1. As present results using ERS 1/2 data were obtained for one day interval, i.e., 25th March 05:00pm to 26th March 05:00 pm, 1996, variation in displacement may be due to presence of snow or wet snow melting over the glacier, since during this time snow melt season is in progress in Gangotri glacier area. Similarly the results of glacier velocity derived using ALOSPALSAR- 2 during 22 March - 19 April 2015 shows the mean velocity of 5.4 to 7.4 cm day-1 during 28 day time interval for full glacier and main trunk glacier respectively. This L-band data is already corrected for Faraday's rotation effects by JAXA, and tropospheric correction are also being applied to refine the results. These results are significant as it is after gap of 20 years that DInSAR methods has given glacier velocity for fast moving Himalayan glacier. RISAT-1 FRS-1 hybrid data is used to create Raney's decompositions parameters, which are further used for glacier zones classification using support vector machine based classification method. The Radarsat-2 and ALOS-PALSAR-2 fully polarized data of year 2010 and 2015 are also used for glacier classification. The identified

  16. Changes in cell death of peripheral blood lymphocytes isolated from children with acute lymphoblastic leukemia upon stimulation with 7 Hz, 30 mT pulsed electromagnetic field.

    PubMed

    Kaszuba-Zwoińska, Jolanta; Ćwiklińska, Magdalena; Balwierz, Walentyna; Chorobik, Paulina; Nowak, Bernadeta; Wójcik-Piotrowicz, Karolina; Ziomber, Agata; Malina-Novak, Kinga; Zaraska, Wiesław; Thor, Piotr J

    2015-03-01

    Pulsed electromagnetic field (PEMF) influenced the viability of proliferating in vitro peripheral blood mononuclear cells (PBMCs) isolated from Crohn's disease patients as well as acute myeloblastic leukemia (AML) patients by induction of cell death, but did not cause any vital changes in cells from healthy donors. Experiments with lymphoid U937 and monocytic MonoMac6 cell lines have shown a protective effect of PEMF on the death process in cells treated with death inducers. The aim of the current study was to investigate the influence of PEMF on native proliferating leukocytes originating from newly diagnosed acute lymphoblastic leukemia (ALL) patients. The effects of exposure to PEMF were studied in PBMCs from 20 children with ALL. PBMCs were stimulated with three doses of PEMF (7 Hz, 30 mT) for 4 h each with 24 h intervals. After the last stimulation, the cells were double stained with annexin V and propidium iodide dye to estimate viability by flow cytometric analysis. The results indicated an increase of annexin V positive as well as double stained annexin V and propidium iodide positive cells after exposure to threefold PEMF stimulation. A low-frequency pulsed electromagnetic field induces cell death in native proliferating cells isolated from ALL patients. The increased vulnerability of proliferating PBMCs to PEMF-induced interactions may be potentially applied in the therapy of ALL. The analysis of expression of apoptosis-related genes revealed changes in mRNA of some genes engaged in the intrinsic apoptotic pathway belonging to the Bcl-2 family and the pathway with apoptosis-inducing factor (AIF) abundance upon PEMF stimulation of PBMCs.

  17. Using High Resolution Tracer Data to Constrain Storage and Flux Estimates in a Spatially Distributed Rainfall-runoff Model

    NASA Astrophysics Data System (ADS)

    Van Huijgevoort, M.; Tetzlaff, D.; Sutanudjaja, E.; Soulsby, C.

    2015-12-01

    Models simulating both stream flow and conservative tracers can provide a more realistic representation of flow paths, storage distributions and mixing processes that is advantageous for many predictions. Conceptual models with such integration have provided useful insights, but tend to be lumped and thus crude representations of catchment processes. Using tracers to aid spatially-distributed models has considerable potential to improve the conceptualisation of the dynamics of internal hydrological stores and fluxes. Here, we examine the strengths and weaknesses of a data-driven, spatially-distributed tracer-aided rainfall-runoff model. The model structure allows the assessment of the effect of landscape properties on the routing and mixing of water and tracers. The model was applied to an experimental site (3.2 km2) in the Scottish Highlands with a unique tracer data set; 4 years of daily isotope ratios in stream water and precipitation were available, as well as 2 years of weekly soil and ground water isotopes. The model evolved from an empirically-based, lumped tracer-aided model previously developed for the catchment. The best model runs were selected from Monte Carlo simulations based on a dual calibration criterion that included objective functions for both stream water isotopes and discharge at the outlet. Model results were also tested against observed spatially-distributed soil water isotope data. Model performance for both criteria was good and the model could reproduce the variable isotope signals in steeper hillslopes where storage was low and damped isotope responses in valley bottom cells with high storage. The model also allows us to estimate the age distributions of internal water fluxes and stream flow and has substantially improved spatial and temporal dynamics of process representation. This gives a more robust framework for projecting the effects of environmental change.

  18. A method for the fast estimation of a battery entropy-variation high-resolution curve - Application on a commercial LiFePO4/graphite cell

    NASA Astrophysics Data System (ADS)

    Damay, Nicolas; Forgez, Christophe; Bichat, Marie-Pierre; Friedrich, Guy

    2016-11-01

    The entropy-variation of a battery is responsible for heat generation or consumption during operation and its prior measurement is mandatory for developing a thermal model. It is generally done through the potentiometric method which is considered as a reference. However, it requires several days or weeks to get a look-up table with a 5 or 10% SoC (State of Charge) resolution. In this study, a calorimetric method based on the inversion of a thermal model is proposed for the fast estimation of a nearly continuous curve of entropy-variation. This is achieved by separating the heats produced while charging and discharging the battery. The entropy-variation is then deduced from the extracted entropic heat. The proposed method is validated by comparing the results obtained with several current rates to measurements made with the potentiometric method.

  19. Fine Resolution Tree Height Estimation from Lidar Data and Its Application in SRTM DEM Correction across Forests of Sierra Nevada, California, USA

    NASA Astrophysics Data System (ADS)

    Su, Y.; Guo, Q.; Ma, Q.; Li, W.

    2015-12-01

    Sierra Nevada (SN) is a mountain range located in the northeastern California, USA, covering an area of 63,100 km2. As one of the most diverse temperate conifer forests on the Earth, forests of SN serve a series of ecosystem functions and are valuable natural heritages for the region and even the country. The still existed gap of accurate fine-resolution tree height estimation has lagged ecological, hydrological and forestry studies within the region. Moreover, the Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM), as one of the most frequently used land surface elevation product in the region, has been proved systematically higher than actual land surface in vegetated mountain areas due to the absorption and reflection effects of canopy on the SRTM radar signal. An accurate fine resolution tree height product across the region is urgently needed for developing models to correct SRTM DEM. In this study, we firstly developed a method to estimate SN tree height distribution (defined by Lorey's height) through the combination of airborne lidar data, spaceborne lidar data, optical imagery, climate surfaces, and field measurements. Over 5 470 km2airborne lidar data and 1 000 plot measurements were collected across the SN to address this mission. Our method involved three main steps: 1) estimate tree heights within airborne lidar footprints using step-wise regression; 2) link the airborne lidar derived tree height to spaceborne lidar data and compute tree heights at spaceborne lidar footprints; 3) extrapolate tree height estimation from spaceborne lidar footprints to the whole region using Random Forest. The obtained SN tree height product showed good correspondence with independent field plot measurements. The coefficient of determination is higher than 0.65, and the root-mean-square error is around 5 m. With the obtained tree height product, we further explored the possibility of correcting SRTM DEM. The results showed that the obtained tree height

  20. Scatter estimation and removal of anti-scatter grid-line artifacts from anthropomorphic head phantom images taken with a high resolution image detector

    NASA Astrophysics Data System (ADS)

    Rana, R.; Jain, A.; Shankar, A.; Bednarek, D. R.; Rudin, S.

    2016-03-01

    In radiography, one of the best methods to eliminate image-degrading scatter radiation is the use of anti-scatter grids. However, with high-resolution dynamic imaging detectors, stationary anti-scatter grids can leave grid-line shadows and moiré patterns on the image, depending upon the line density of the grid and the sampling frequency of the x-ray detector. Such artifacts degrade the image quality and may mask small but important details such as small vessels and interventional device features. Appearance of these artifacts becomes increasingly severe as the detector spatial resolution is improved. We have previously demonstrated that, to remove these artifacts by dividing out a reference grid image, one must first subtract the residual scatter that penetrates the grid; however, for objects with anatomic structure, scatter varies throughout the FOV and a spatially differing amount of scatter must be subtracted. In this study, a standard stationary Smit-Rontgen X-ray grid (line density - 70 lines/cm, grid ratio - 13:1) was used with a high-resolution CMOS detector, the Dexela 1207 (pixel size - 75 micron) to image anthropomorphic head phantoms. For a 15 x 15cm FOV, scatter profiles of the anthropomorphic head phantoms were estimated then iteratively modified to minimize the structured noise due to the varying grid-line artifacts across the FOV. Images of the anthropomorphic head phantoms taken with the grid, before and after the corrections, were compared demonstrating almost total elimination of the artifact over the full FOV. Hence, with proper computational tools, antiscatter grid artifacts can be corrected, even during dynamic sequences.

  1. Elevation change estimates of the Barnes Ice Cap from combined CryoSat-2 altimetry measurements and high resolution stereo-photogrammetric DEM

    NASA Astrophysics Data System (ADS)

    de la Peña, S.; Howat, I. M.; Noh, M. J.; Shum, C. K.

    2015-12-01

    Mass losses from glaciers and small ice caps in the Canadian Arctic have accelerated dramatically in the last decade due to warming. The Barnes Ice Cap, a remnant of the Laurentide Ice Sheet, contains the oldest ice in the Canadian Arctic, and has been particularly sensitive to changes in atmospheric temperature. Although relatively flat at the top, the ice cap is located along the Arctic Cordillera, dominated by alpine mountains with sharp peaks and ridges which limited the accuracy of measurements from past satellite radar altimeter missions. The interferometric capabilities of the CryoSat-2 radar altimeter has improved our capacity to measure volume changes over steep topography, but still face potential limitations over irregular terrain and glaciated areas with high surface roughness, which in the Arctic has increased as a consequence of intensified surface melt. Over rough topography, such as the one characterized by crevassed fields, surface roughness is high relative to the altimeter footprint, and estimating the incidence angle of the altimeter signal is not always possible. Here, a high-resolution stereo-photogrammetric DEM generated from stereo-mode Worldview satellite imagery is used to estimate surface slope of the glaciated terrain and derive the across-track incidence angle of the CryoSat-2 radar echo. The unprecedented accuracy of the DEM allows it to then be used as a reference to increase spatial density of elevation change measurements. Elevation change estimates for the period of 2011-2015 show a thinning of 1.46 ± 0.21 yr-1 on average, more than twice the thinning rates estimated a decade ago. The methodology increase spatial coverage of repeated altimetry measurements, and may improve elevation retrieval from altimetry signals in glaciated areas subject to summer surface melt.

  2. High resolution inventory of re-estimating ammonia emissions from agricultural fertilizer in China from 1978 to 2008

    NASA Astrophysics Data System (ADS)

    Xu, P.; Lin, Y. H.; Liao, Y. J.; Zhao, C. X.; Wang, G. S.; Luan, S. J.

    2015-09-01

    The quantification of ammonia (NH3) emissions is essential to the more accurate quantification of atmospheric nitrogen deposition, improved air quality and the assessment of ammonia-related agricultural policy and climate mitigation strategies. The quantity, geographic distribution and historical trends of these emissions remain largely uncertain. In this paper, a new Chinese agricultural fertilizer NH3 (CAF_NH3) emissions inventory has been compiled that exhibits the following improvements: (1) a 1 km × 1 km gridded map on the county level was developed for 2008, (2) a combined bottom-up and top-down method was used for the local correction of emission factors (EFs) and parameters, (3) the spatial and temporal patterns of historical time trends for 1978-2008 were estimated and the uncertainties were quantified for the inventories, and (4) a sensitivity test was performed in which a province-level disaggregated map was compared with CAF_NH3 emissions for 2008. The total CAF_NH3 emissions for 2008 were 8.4 Tg NH3 yr-1 (a 6.6-9.8 Tg interquartile range). From 1978 to 2008, annual NH3 emissions fluctuated with three peaks (1987, 1996 and 2005), and total emissions increased from 3.2 to 8.4 Tg at an annual rate of 3.0 %. During the study period, the contribution of livestock manure spreading increased from 37.0 to 45.5 % because of changing fertilization practices and the rapid increase in egg, milk and meat consumption. The average contribution of synthetic fertilizer, which has a positive effect on crop yields, was approximately 38.3 % (minimum: 33.4 %; maximum: 42.7 %). With rapid urbanization causing a decline in the rural population, the contribution of the rural excrement sector varied widely between 20.3 and 8.5 %. The average contributions of cake fertilizer and straw returning were approximately 3.8 and 4.5 %, respectively, thus small and stable. Collectively, the CAF_NH3 emissions reflect the nation's agricultural policy to a certain extent. An effective

  3. Estimation of net ecosystem production in Asia using the diagnostic-type ecosystem model with a 10 km grid-scale resolution

    NASA Astrophysics Data System (ADS)

    Sasai, Takahiro; Obikawa, Hiroki; Murakami, Kazutaka; Kato, Soushi; Matsunaga, Tsuneo; Nemani, Ramakrishna R.

    2016-06-01

    The terrestrial carbon cycle in Asia is highly uncertain, and it affects our understanding of global warming. One of the important issues is the need for an enhancement of spatial resolution, since local regions in Asia are heterogeneous with regard to meteorology, land form, and land cover type, which greatly impacts the detailed spatial patterns in its ecosystem. Thus, an important goal of this study is to reasonably reproduce the heterogeneous biogeochemical patterns in Asia by enhancing the spatial resolution of the ecosystem model biosphere model integrating eco-physiological and mechanistic approaches using satellite data (BEAMS). We estimated net ecosystem production (NEP) over eastern Asia and examined the spatial differences in the factors controlling NEP by using a 10 km grid-scale approach over two different decades (2001-2010 and 2091-2100). The present and future meteorological inputs were derived from satellite observations and the downscaled Coupled Model Intercomparison Project Phase 5 (CMIP5) data set, respectively. The results showed that the present NEP in whole eastern Asia was carbon source (-214.9 TgC yr-1) and in future scenarios, the greatest positive (76.4 TgC yr-1) and least negative (-95.9 TgC yr-1) NEPs were estimated from the Representative Concentration Pathways (RCP) 6.0 and RCP8.5 scenarios, respectively. Calculated annual NEP in RCP8.5 was mostly positive in the southern part of East Asia and Southeast Asia and negative in northern and central parts of East Asia. Under the RCP scenario with higher greenhouse gases emission (RCP8.5), deciduous needleleaf and mixed forests distributed in the middle and high latitudes served as carbon source. In contrast, evergreen broadleaf forests distributed in low latitudes served as carbon sink. The sensitivity study demonstrated that the spatial tendency of NEP was largely influenced by atmospheric CO2 and temperature.

  4. Estimating Agricultural Water Use using the Operational Simplified Surface Energy Balance Evapotranspiration Estimation Method

    NASA Astrophysics Data System (ADS)

    Forbes, B. T.

    2015-12-01

    Due to the predominantly arid climate in Arizona, access to adequate water supply is vital to the economic development and livelihood of the State. Water supply has become increasingly important during periods of prolonged drought, which has strained reservoir water levels in the Desert Southwest over past years. Arizona's water use is dominated by agriculture, consuming about seventy-five percent of the total annual water demand. Tracking current agricultural water use is important for managers and policy makers so that current water demand can be assessed and current information can be used to forecast future demands. However, many croplands in Arizona are irrigated outside of areas where water use reporting is mandatory. To estimate irrigation withdrawals on these lands, we use a combination of field verification, evapotranspiration (ET) estimation, and irrigation system qualification. ET is typically estimated in Arizona using the Modified Blaney-Criddle method which uses meteorological data to estimate annual crop water requirements. The Modified Blaney-Criddle method assumes crops are irrigated to their full potential over the entire growing season, which may or may not be realistic. We now use the Operational Simplified Surface Energy Balance (SSEBop) ET data in a remote-sensing and energy-balance framework to estimate cropland ET. SSEBop data are of sufficient resolution (30m by 30m) for estimation of field-scale cropland water use. We evaluate our SSEBop-based estimates using ground-truth information and irrigation system qualification obtained in the field. Our approach gives the end user an estimate of crop consumptive use as well as inefficiencies in irrigation system performance—both of which are needed by water managers for tracking irrigated water use in Arizona.

  5. Estimation of Effective Soil Hydraulic Properties Using Data From High Resolution Gamma Densiometry and Tensiometers of Multi-Step-Outflow Experiments

    NASA Astrophysics Data System (ADS)

    Werisch, Stefan; Lennartz, Franz; Bieberle, Andre

    2013-04-01

    Dynamic Multi Step Outflow (MSO) experiments serve for the estimation of the parameters from soil hydraulic functions like e.g. the Mualem van Genuchten model. The soil hydraulic parameters are derived from outflow records and corresponding matric potential measurements from commonly a single tensiometer using inverse modeling techniques. We modified the experimental set up allowing for simultaneous measurements of the matric potential with three tensiometers and the water content using a high-resolution gamma-ray densiometry measurement system (Bieberle et al., 2007, Hampel et al., 2007). Different combinations of the measured time series were used for the estimation of effective soil hydraulic properties, representing different degrees of information of the "hydraulic reality" of the sample. The inverse modeling task was solved with the multimethod search algorithm AMALGAM (Vrugt et al., 2007) in combination with the Hydrus1D model (Šimúnek et al., 2008). Subsequently, the resulting effective soil hydraulic parameters allow the simulation of the MSO experiment and the comparison of model results with observations. The results show that the information of a single tensiometer together with the outflow record result in a set of effective soil hydraulic parameters producing an overall good agreement between the simulation and the observation for the location of the tensiometer. Significantly deviating results are obtained for the other tensiometer positions using this parameter set. Inclusion of more information, such as additional matric potential measurements with the according water contents within the optimization procedure lead to different, more representative hydraulic parameters which improved the overall agreement significantly. These findings indicate that more information about the soil hydraulic state variables in space and time are necessary to obtain effective soil hydraulic properties of soil core samples. Bieberle, A., Kronenberg, J., Schleicher, E

  6. Oligomeric TTR V30M aggregates compromise cell viability, erythropoietin gene expression and promoter activity in the human hepatoma cell line Hep3B.

    PubMed

    Moreira, Luciana; Beirão, João Melo; Beirão, Idalina; Pinho e Costa, Paulo

    2015-01-01

    Familial amyloidotic polyneuropathy, ATTRV30M (p. TTRV50M) amyloidosis, is a neurodegenerative disease characterized by systemic extracellular amyloid deposition of a mutant transthyretin, TTR V30M. Anemia, with low erythropoietin (EPO) levels and spared kidney function, affects about 25% of symptomatic patients, suggesting a blockage of EPO-producing cells. Early non-fibrillar TTR aggregates are highly cytotoxic, inducing oxidative stress, the expression of apoptosis-related molecules and secretion of pro-inflammatory cytokines, factors capable of inhibiting EPO production. Low EPO levels in these patients are not related to renal amyloid deposition or the presence of circulating TTR V30M. However, the role of early non-fibrillar TTR aggregates remains unexplored. We used the EPO producing Hep3B human hepatoma cell line to study the effect of TTR oligomeric aggregates on EPO expression. Hep3B cells were incubated with soluble and oligomeric TTR V30M, and cell proliferation as well as caspase 3/7 activation was evaluated. Relative quantification of EPO mRNA transcripts was performed by real-time PCR. Significant reductions in cell viability (13 ± 7.3%) and activation of caspases 3/7 were seen after 24 h in the presence of oligomeric TTR V30M. Also, EPO expression was significantly reduced (50 ± 2.8%), in normoxic conditions. A reporter assay was constructed with a PCR fragment of the EPO promoter linked to the luciferase gene to evaluate the role of transcription factors targeting the promoter. A significant reduction of EPO promoter activity (53 ± 6.5%) was observed in transfected cells exposed to TTR oligomers. Our results show that oligomeric TTR V30M reduces EPO expression, at least in part through inhibition of promoter activity.

  7. Mangrove Blue Carbon stocks and change estimation from PolInSAR, Lidar and High Resolution Stereo Imagery combined with Forest Cover change mapping

    NASA Astrophysics Data System (ADS)

    Zalles, V.; Fatoyinbo, T. E.; Simard, M.; Lagomasino, D.; Lee, S. K.; Trettin, C.; Feliciano, E. A.; Hansen, M.; John, P.

    2015-12-01

    Mangroves and tidal wetlands have the highest carbon density among terrestrial ecosystems. Although they only represent 3 % of the total forest area (or 0.01 % of land area), C emissions from mangrove destruction alone at current rates could be equivalent to 10 % of carbon emissions from deforestation. One of the main challenges to implementing carbon mitigation projects is measuring carbon, efficiently, effectively, and safely. In mangroves especially, the extreme difficulty of the terrain has hindered the establishment of sufficient field plots needed to accurately measure carbon on the scale necessary to relate remotely sensed measurements with field measurements at accuracies required for REDD and other C trading mechanisms. In this presentation we will showcase the methodologies for, and the remote sensing products necessary to implement MRV (monitoring, reporting and verification) systems in Coastal Blue Carbon ecosystems. Specifically, we will present new methods to estimate aboveground biomass stocks and change in mangrove ecosystems using remotely sensed data from Interferometric SAR from the TanDEM-X mission, commercial airborne Lidar, High Resolution Stereo-imagery, and timeseries analysis of Landsat imagery in combination with intensive field measurements of above and belowground carbon stocks. Our research is based on the hypothesis that by combining field measurements, commercial airborne Lidar, optical and Pol-InSAR data, we are able to estimate Mangrove blue carbon storage with an error under 20% at the project level and permit the evaluation of UNFCCC mechanisms for the mitigation of carbon emissions from coastal ecosystems.

  8. High-resolution 3D seismic reflection imaging across active faults and its impact on seismic hazard estimation in the Tokyo metropolitan area

    NASA Astrophysics Data System (ADS)

    Ishiyama, Tatsuya; Sato, Hiroshi; Abe, Susumu; Kawasaki, Shinji; Kato, Naoko

    2016-10-01

    We collected and interpreted high-resolution 3D seismic reflection data across a hypothesized fault scarp, along the largest active fault that could generate hazardous earthquakes in the Tokyo metropolitan area. The processed and interpreted 3D seismic cube, linked with nearby borehole stratigraphy, suggests that a monocline that deforms lower Pleistocene units is unconformably overlain by middle Pleistocene conglomerates. Judging from structural patterns and vertical separation on the lower-middle Pleistocene units and the ground surface, the hypothesized scarp was interpreted as a terrace riser rather than as a manifestation of late Pleistocene structural growth resulting from repeated fault activity. Devastating earthquake scenarios had been predicted along the fault in question based on its proximity to the metropolitan area, however our new results lead to a significant decrease in estimated fault length and consequently in the estimated magnitude of future earthquakes associated with reactivation. This suggests a greatly reduced seismic hazard in the Tokyo metropolitan area from earthquakes generated by active intraplate crustal faults.

  9. Grazer Effects on Stream Primary Production and Nitrate Utilization: Estimating Feedbacks Under Reduced Nitrate Levels at High-Temporal Resolutions from the Patch to Reach-Scale

    NASA Astrophysics Data System (ADS)

    Reijo, C. J.; Cohen, M. J.

    2015-12-01

    While nutrient enrichment is often identified as the leading cause for changes in stream gross primary production (GPP) and shifts in vegetative communities, other factors such as grazers influence overall stream structure and function. Evidence shows that grazers are a top-down control on algae in streams; however, the specific feedbacks between overall stream metabolism, grazer effects, and nutrient cycling have been variable and little is known about these interactions at nutrient levels below ambient. To further our understanding of these linkages, a nutrient depletion chamber was created and paired with high-resolution in situ sensors to estimate stream metabolism and characterize nitrate uptake (UNO3) pathways (i.e. plant uptake and denitrification). The Plexiglas chamber blocks flow and nutrient supply, inserts into upper sediments, allows light in and sediment-water-air interactions to occur. At Gum Slough Springs, FL, nitrate was reduced from ambient levels (1.40 mg N/L) to below regulatory thresholds (ca. 0.20 mg N/L) within one week. Paired chambers with and without the presence of snails (Elimia floridensis) were deployed across submerged aquatic vegetation (SAV; Vallisneria americana) and algae (Lyngbya) substrates. Results show that GPP and UNO3 were higher under SAV (70 g O2/m2/d and 300 mg NO3/m2/d, respectively) and a general lack of nutrient limitation even at low [NO3]. Grazer effects differed by vegetation type as it alleviated the reduction of NO3 levels and GPP under SAV but enhanced the decrease of algal GPP and NO3 levels over time. Continued work includes estimating grazer effects on denitrification, quantifying snail nutrient excretion contributions, and scaling up all estimates from the patch to reach level. Overall, this study will further our understanding of grazer-production-nutrient interactions within stream systems, making it possible to predict changes in feedbacks when one part of the biotic or abiotic ecosystem is altered.

  10. Topographic and Acoustic Estimates of Grain-Scale Roughness from High-Resolution Multibeam Echo-Sounder: Examples from the Colorado River in Marble and Grand Canyons.

    NASA Astrophysics Data System (ADS)

    Buscombe, D.; Grams, P. E.

    2014-12-01

    High-frequency (several hundred kilohertz) multibeam echo-sounder (MBES) systems have the potential to provide complete coverage of large areas (km2) of the bed, rapidly (mins to hrs), at high resolution (cm2), and with high positional accuracy (cm). Here, we explore the use of MBES data to estimate grain-scale roughness of submerged riverbed sediment. There are two broad approaches: 1) using digital elevation models constructed from depth soundings, and 2) using acoustic backscatter. We discuss the relative merits of both approaches using examples from data collected on the Colorado River in Marble and Grand Canyons, Arizona, USA. The primary advantage of acoustic backscatter over topography from soundings, for the purposes of sediment classification, is the potential to distinguish between sediment at a higher resolution. This is because soundings are point measurements, whereas a recorded backscatter magnitude is the integral of backscattered sound from all scatterers in the insonified area. In addition, this acoustic return contains information about both the roughness and the hardness/impedance of the sediment. The statistics of backscatter magnitudes alone are found to be a poor discriminator between sediment types perhaps because, using our 400 kHz system, the scattering regime changes from Rayleigh (sound scattering by particles smaller than the sound wavelength) for fine sand, to geometric (scattering by larger-than-sound-wavelength particles) for substrates coarser than sand. However, simple measures derived from backscatter power spectra (namely, the variance, integral lengthscale, and the intercept and slope from a power-law form - see Figure) are found to distinguish between patches of sand, gravel, cobbles and boulders. Using this dependence, we present a new data-driven approach to classify grain-scale roughness, developed by comparing the spectral properties of backscatter with bed-sediment observations using geo-referenced underwater video.

  11. Application of high-resolution time-of-flight chemical ionization mass spectrometry measurements to estimate volatility distributions of α-pinene and naphthalene oxidation products

    DOE PAGES

    Chhabra, P. S.; Lambe, A. T.; Canagaratna, M. R.; ...

    2015-01-05

    Recent developments in high-resolution time-of-flight chemical ionization mass spectrometry (HR-ToF-CIMS) have made it possible to directly detect atmospheric organic compounds in real time with high sensitivity and with little or no fragmentation, including low-volatility, highly oxygenated organic vapors that are precursors to secondary organic aerosol formation. Here, using ions identified by high-resolution spectra from an HR-ToF-CIMS with acetate reagent ion chemistry, we develop an algorithm to estimate the vapor pressures of measured organic acids. The algorithm uses identified ion formulas and calculated double bond equivalencies, information unavailable in quadrupole CIMS technology, as constraints for the number of possible oxygen-containing functionalmore » groups. The algorithm is tested with acetate chemical ionization mass spectrometry (acetate-CIMS) spectra of O3 and OH oxidation products of α-pinene and naphthalene formed in a flow reactor with integrated OH exposures ranged from 1.2 × 1011 to 9.7 × 1011 molec s cm−3, corresponding to approximately 1.0 to 7.5 days of equivalent atmospheric oxidation. Measured gas-phase organic acids are similar to those previously observed in environmental chamber studies. For both precursors, we find that acetate-CIMS spectra capture both functionalization (oxygen addition) and fragmentation (carbon loss) as a function of OH exposure. The level of fragmentation is observed to increase with increased oxidation. The predicted condensed-phase secondary organic aerosol (SOA) average acid yields and O/C and H/C ratios agree within uncertainties with previous chamber and flow reactor measurements and ambient CIMS results. While acetate reagent ion chemistry is used to selectively measure organic acids, in principle this method can be applied to additional reagent ion chemistries depending on the application.« less

  12. Estimation de parametres structuraux des arbres dans une savane a partir de mesures LiDAR terrestre et d'imagerie a tres haute resolution spatiale

    NASA Astrophysics Data System (ADS)

    Beland, Martin

    to produce the leaf area, estimates. The second part of the thesis explores the combination of the tree representations generated in the first part with a ray tracing model to simulate the interactions of light with tree crowns. This approach is highly innovative and our study showed its potential to improve our understanding of the factors influencing the radiative environment in a savanna. The methods presented offer a solution to map leaf area at the individual tree scale over large areas from very high spatial resolution imagery. Mots-cles: Scanneur LiDAR terrestre, voxel, distribution 3D de surface foliaire, savanes, densite de surface foliaire (LAD), indice de surface foliaire (LAI), effets d'occlusion, parametrage, cartographie de la surface foliaire, lancer de rayons, modelisation du transfert radiatif.

  13. a Simple and Effective Retrieval of Land Surface Temperature Using a New Reflectance Based Emissivity Estimation Technique

    NASA Astrophysics Data System (ADS)

    Nithiyanandam, Y.; Nichol, J. E.

    2016-06-01

    Emissivity is a significant factor in determining land surface temperature (LST) retrieved from the thermal infrared (TIR) satellite images. A new simplified method (reflectance method) for emissivity correction was developed in this study while estimating emissivity values at a spatial resolution of 30 m from the radiance values of the SWIR image. This in turn enables mapping surface temperatures at a much finer spatial resolution (30 m). Temperatures so estimated are validated against surface temperatures measured in the ground by thermocouple data loggers recorded during satellite overpass time. In this study, surface emissivity values are derived directly from the AST_ L1B images. The reflectance method estimates temperature at higher spatial resolution of 30 m when compared to the 90 m spatial resolution of TES and reference channel methods. Temperature determined for the daytime image of 30th November 2007 using different emissivity techniques was compared with the temperatures measured on the field using thermocouple data loggers. It is observed that the estimates from the reflectance method are much closer to the field measurements than the TES and reference channel methods. The temperature difference values range from 0.2 to 2.3 °C, 0.15 to 5.6 °C, and 2.6 to 8.6 °C for the reflectance method, normalization method and reference channel method, respectively. The new reflectance emissivity techniques i.e. reflectance method exhibits the least deviation from the field measured temperature values. While considering the accuracy of data logger (1 °C) the reflectance method enables one to map surface temperature precisely than other two methods.

  14. Very High Resolution Mapping of Tree Cover Using Scalable Deep Learning Architectures

    NASA Astrophysics Data System (ADS)

    ganguly, sangram; basu, saikat; nemani, ramakrishna; mukhopadhyay, supratik; michaelis, andrew; votava, petr; saatchi, sassan

    2016-04-01

    Several studies to date have provided an extensive knowledge base for estimating forest aboveground biomass (AGB) and recent advances in space-based modeling of the 3-D canopy structure, combined with canopy reflectance measured by passive optical sensors and radar backscatter, are providing improved satellite-derived AGB density mapping for large scale carbon monitoring applications. A key limitation in forest AGB estimation from remote sensing, however, is the large uncertainty in forest cover estimates from the coarse-to-medium resolution satellite-derived land cover maps (present resolution is limited to 30-m of the USGS NLCD Program). As part of our NASA Carbon Monitoring System Phase II activities, we have demonstrated that uncertainties in forest cover estimates at the Landsat scale result in high uncertainties in AGB estimation, predominantly in heterogeneous forest and urban landscapes. We have successfully tested an approach using scalable deep learning architectures (Feature-enhanced Deep Belief Networks and Semantic Segmentation using Convolutional Neural Networks) and High-Performance Computing with NAIP air-borne imagery data for mapping tree cover at 1-m over California and Maryland. Our first high resolution satellite training label dataset from the NAIP data can be found here at http://csc.lsu.edu/~saikat/deepsat/ . In a comparison with high resolution LiDAR data available over selected regions in the two states, we found our results to be promising both in terms of accuracy as well as our ability to scale nationally. In this project, we propose to estimate very high resolution forest cover for the continental US at spatial resolution of 1-m in support of reducing uncertainties in the AGB estimation. The proposed work will substantially contribute to filling the gaps in ongoing carbon monitoring research and help quantifying the errors and uncertainties in related carbon products.

  15. Comparison of 3D-OP-OSEM and 3D-FBP reconstruction algorithms for High-Resolution Research Tomograph studies: effects of randoms estimation methods

    NASA Astrophysics Data System (ADS)

    van Velden, Floris H. P.; Kloet, Reina W.; van Berckel, Bart N. M.; Wolfensberger, Saskia P. A.; Lammertsma, Adriaan A.; Boellaard, Ronald

    2008-06-01

    The High-Resolution Research Tomograph (HRRT) is a dedicated human brain positron emission tomography (PET) scanner. Recently, a 3D filtered backprojection (3D-FBP) reconstruction method has been implemented to reduce bias in short duration frames, currently observed in 3D ordinary Poisson OSEM (3D-OP-OSEM) reconstructions. Further improvements might be expected using a new method of variance reduction on randoms (VRR) based on coincidence histograms instead of using the delayed window technique (DW) to estimate randoms. The goal of this study was to evaluate VRR in combination with 3D-OP-OSEM and 3D-FBP reconstruction techniques. To this end, several phantom studies and a human brain study were performed. For most phantom studies, 3D-OP-OSEM showed higher accuracy of observed activity concentrations with VRR than with DW. However, both positive and negative deviations in reconstructed activity concentrations and large biases of grey to white matter contrast ratio (up to 88%) were still observed as a function of scan statistics. Moreover 3D-OP-OSEM+VRR also showed bias up to 64% in clinical data, i.e. in some pharmacokinetic parameters as compared with those obtained with 3D-FBP+VRR. In the case of 3D-FBP, VRR showed similar results as DW for both phantom and clinical data, except that VRR showed a better standard deviation of 6-10%. Therefore, VRR should be used to correct for randoms in HRRT PET studies.

  16. Variability of Marine Aerosol Fine-Mode Fraction and Estimates of Anthropogenic Aerosol Component Over Cloud-Free Oceans from the Moderate Resolution Imaging Spectroradiometer (MODIS)

    NASA Technical Reports Server (NTRS)

    Yu, Hongbin; Chin, Mian; Remer, Lorraine A.; Kleidman, Richard G.; Bellouin, Nicolas; Bian, Huisheng; Diehl, Thomas

    2009-01-01

    In this study, we examine seasonal and geographical variability of marine aerosol fine-mode fraction (f(sub m)) and its impacts on deriving the anthropogenic component of aerosol optical depth (tau(sub a)) and direct radiative forcing from multispectral satellite measurements. A proxy of f(sub m), empirically derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 5 data, shows large seasonal and geographical variations that are consistent with the Goddard Chemistry Aerosol Radiation Transport (GOCART) and Global Modeling Initiative (GMI) model simulations. The so-derived seasonally and spatially varying f(sub m) is then implemented into a method of estimating tau(sub a) and direct radiative forcing from the MODIS measurements. It is found that the use of a constant value for fm as in previous studies would have overestimated Ta by about 20% over global ocean, with the overestimation up to 45% in some regions and seasons. The 7-year (2001-2007) global ocean average tau(sub a) is 0.035, with yearly average ranging from 0.031 to 0.039. Future improvement in measurements is needed to better separate anthropogenic aerosol from natural ones and to narrow down the wide range of aerosol direct radiative forcing.

  17. Use of high-resolution imagery acquired from an unmanned aircraft system for fluvial mapping and estimating water-surface velocity in rivers

    NASA Astrophysics Data System (ADS)

    Kinzel, P. J.; Bauer, M.; Feller, M.; Holmquist-Johnson, C.; Preston, T.

    2013-12-01

    The use of unmanned aircraft systems (UAS) for environmental monitoring in the United States is anticipated to increase in the coming years as the Federal Aviation Administration (FAA) further develops guidelines to permit their integration into the National Airspace System. The U.S. Geological Survey's (USGS) National Unmanned Aircraft Systems Project Office routinely obtains Certificates of Authorization from the FAA for utilizing UAS technology for a variety of natural resource applications for the U.S. Department of the Interior (DOI). We evaluated the use of a small UAS along two reaches of the Platte River near Overton Nebraska, USA, to determine the accuracy of the system for mapping the extent and elevation of emergent sandbars and to test the ability of a hovering UAS to identify and track tracers to estimate water-surface velocity. The UAS used in our study is the Honeywell Tarantula Hawk RQ16 (T-Hawk), developed for the U.S. Army as a reconnaissance and surveillance platform. The T-Hawk has been recently modified by USGS, and certified for airworthiness by the DOI - Office of Aviation Services, to accommodate a higher-resolution imaging payload than was originally deployed with the system. The T-Hawk is currently outfitted with a Canon PowerShot SX230 HS with a 12.1 megapixel resolution and intervalometer to record images at a user defined time step. To increase the accuracy of photogrammetric products, orthoimagery and DEMs using structure-from-motion (SFM) software, we utilized ground control points in the study reaches and acquired imagery using flight lines at various altitudes (200-400 feet above ground level) and oriented both parallel and perpendicular to the river. Our results show that the mean error in the elevations derived from SFM in the upstream reach was 17 centimeters and horizontal accuracy was 6 centimeters when compared to 4 randomly distributed targets surveyed on emergent sandbars. In addition to the targets, multiple transects were

  18. 3D Transient Hydraulic Tomography (3DTHT): An Efficient Field and Modeling Method for High-Resolution Estimation of Aquifer Heterogeneity

    NASA Astrophysics Data System (ADS)

    Barrash, W.; Cardiff, M. A.; Kitanidis, P. K.

    2012-12-01

    The distribution of hydraulic conductivity (K) is a major control on groundwater flow and contaminant transport. Our limited ability to determine 3D heterogeneous distributions of K is a major reason for increased costs and uncertainties associated with virtually all aspects of groundwater contamination management (e.g., site investigations, risk assessments, remediation method selection/design/operation, monitoring system design/operation). Hydraulic tomography (HT) is an emerging method for directly estimating the spatially variable distribution of K - in a similar fashion to medical or geophysical imaging. Here we present results from 3D transient field-scale experiments (3DTHT) which capture the heterogeneous K distribution in a permeable, moderately heterogeneous, coarse fluvial unconfined aquifer at the Boise Hydrogeophysical Research Site (BHRS). The results are verified against high-resolution K profiles from multi-level slug tests at BHRS wells. The 3DTHT field system for well instrumentation and data acquisition/feedback is fully modular and portable, and the in-well packer-and-port system is easily assembled and disassembled without expensive support equipment or need for gas pressurization. Tests are run for 15-20 min and the aquifer is allowed to recover while the pumping equipment is repositioned between tests. The tomographic modeling software developed uses as input observations of temporal drawdown behavior from each of numerous zones isolated in numerous observation wells during a series of pumping tests conducted from numerous isolated intervals in one or more pumping wells. The software solves for distributed K (as well as storage parameters Ss and Sy, if desired) and estimates parameter uncertainties using: a transient 3D unconfined forward model in MODFLOW, the adjoint state method for calculating sensitivities (Clemo 2007), and the quasi-linear geostatistical inverse method (Kitanidis 1995) for the inversion. We solve for K at >100,000 sub-m3

  19. Estimation of the Components of the Carbon and Water Budgets for Winter Wheat by Combining High Resolution Remote Sensing Data with a Crop Model

    NASA Astrophysics Data System (ADS)

    Veloso, A.; Ceschia, E.

    2014-12-01

    Croplands occupy more than one third of Earth's terrestrial surface contributing to climate change and also being impacted by those changes, since their production is conditioned by climatic conditions and water resources. It is thus essential to quantify and analyze the production and the main components of the carbon and water cycles for crop ecosystems. We propose here a regional modeling approach that combines: high spatial and temporal resolutions (HSTR) optical remote sensing data, a simple crop model and an extensive set of in-situ measurements for model's calibration and validation. The model, named SAFYE-CO2 (Simple Algorithm for Fluxes and Yield Estimates), is a daily time step model based on Monteith's light-use efficiency theory and coupled with a water budget module (FAO-56 method). SAFYE-CO2 estimates components of the carbon budget (gross primary production (GPP), ecosystem respiration (Reco), net ecosystem exchange (NEE), …) and of the crop water cycle (evaporation, transpiration, evapotranspiration (ETR) and soil water content) and also time courses of dry aboveground biomass and yield by assimilating Green Area Index (GAI) data obtained from HSTR satellite observations. For this work, we used a unique set of Formosat-2 and SPOT images acquired from 2006 to 2011 in southwest France. Crop and soil model parameters were set using both in-situ measurements and values found in the literature. Phenological parameters were calibrated by the GAI assimilation. The results indicate that the model correctly reproduces winter wheat biomass and yield production (relative error about 25%) for years with contrasted climatic conditions. The estimated net carbon flux components were overall in agreement with the flux measurements, presenting good correlations (R² about 0.9 for GPP, 0.77 for Reco and 0.84 for NEE). Regarding the ETR, a good correlation (R2 about 0.73) and satisfactory errors (RMSE about 0.47 mm.d-1) were found. Carbon and water budgets as well

  20. Estimation of Carbon Budgets for Croplands by Combining High Resolution Remote Sensing Data with a Crop Model and Validation Ground Data

    NASA Astrophysics Data System (ADS)

    Mangiarotti, S.; Veloso, A.; Ceschia, E.; Tallec, T.; Dejoux, J. F.

    2015-12-01

    Croplands occupy large areas of Earth's land surface playing a key role in the terrestrial carbon cycle. Hence, it is essential to quantify and analyze the carbon fluxes from those agro-ecosystems, since they contribute to climate change and are impacted by the environmental conditions. In this study we propose a regional modeling approach that combines high spatial and temporal resolutions (HSTR) optical remote sensing data with a crop model and a large set of in-situ measurements for model calibration and validation. The study area is located in southwest France and the model that we evaluate, called SAFY-CO2, is a semi-empirical one based on the Monteith's light-use efficiency theory and adapted for simulating the components of the net ecosystem CO2 fluxes (NEE) and of the annual net ecosystem carbon budgets (NECB) at a daily time step. The approach is based on the assimilation of satellite-derived green area index (GAI) maps for calibrating a number of the SAFY-CO2 parameters linked to crop phenology. HSTR data from the Formosat-2 and SPOT satellites were used to produce the GAI maps. The experimental data set includes eddy covariance measurements of net CO2 fluxes from two experimental sites and partitioned into gross primary production (GPP) and ecosystem respiration (Reco). It also includes measurements of GAI, biomass and yield between 2005 and 2011, focusing on the winter wheat crop. The results showed that the SAFY-CO2 model correctly reproduced the biomass production, its dynamic and the yield (relative errors about 24%) in contrasted climatic, environmental and management conditions. The net CO2 flux components estimated with the model were overall in agreement with the ground data, presenting good correlations (R² about 0.93 for GPP, 0.77 for Reco and 0.86 for NEE). The evaluation of the modelled NECB for the different site-years highlighted the importance of having accurate estimates of each component of the NECB. Future works aim at considering

  1. Variability in Surface BRDF at Different Spatial Scales (30 m-500 m) Over a Mixed Agricultural Landscape as Retrieved from Airborne and Satellite Spectral Measurements

    NASA Technical Reports Server (NTRS)

    Roman, Miguel O.; Gatebe, Charles K.; Schaaf, Crystal B.; Poudyal, Rajesh; Wang, Zhousen; King, Michael D.

    2011-01-01

    Over the past decade, the role of multiangle remote sensing has been central to the development of algorithms for the retrieval of global land surface properties including models of the bidirectional reflectance distribution function (BRDF), albedo, land cover/dynamics, burned area extent, as well as other key surface biophysical quantities represented by the anisotropic reflectance characteristics of vegetation. In this study, a new retrieval strategy for fine-to-moderate resolution multiangle observations was developed, based on the operational sequence used to retrieve the Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 5 reflectance and BRDF/albedo products. The algorithm makes use of a semiempirical kernel-driven bidirectional reflectance model to provide estimates of intrinsic albedo (i.e., directional-hemispherical reflectance and bihemispherical reflectance), model parameters describing the BRDF, and extensive quality assurance information. The new retrieval strategy was applied to NASA's Cloud Absorption Radiometer (CAR) data acquired during the 2007 Cloud and Land Surface Interaction Campaign (CLASIC) over the well-instrumented Atmospheric Radiation Measurement Program (ARM) Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) site in Oklahoma, USA. For the case analyzed, we obtained approx.1.6 million individual surface bidirectional reflectance factor (BRF) retrievals, from nadir to 75 off-nadir, and at spatial resolutions ranging from 3 m - 500 m. This unique dataset was used to examine the interaction of the spatial and angular characteristics of a mixed agricultural landscape; and provided the basis for detailed assessments of: (1) the use of a priori knowledge in kernel-driven BRDF model inversions; (2) the interaction between surface reflectance anisotropy and instrument spatial resolution; and (3) the uncertain ties that arise when sub-pixel differences in the BRDF are aggregated to a moderate resolution satellite pixel

  2. Variability in Surface BRDF at Different Spatial Scales (30m-500m) Over a Mixed Agricultural Landscape as Retrieved from Airborne and Satellite Spectral Measurements

    NASA Technical Reports Server (NTRS)

    Roman, Miguel O.; Gatebe, Charles K.; Schaaf, Crystal B.; Poudyal, Rajesh; Wang, Zhuosen; King, Michael D.

    2012-01-01

    Over the past decade, the role of multiangle 1 remote sensing has been central to the development of algorithms for the retrieval of global land surface properties including models of the bidirectional reflectance distribution function (BRDF), albedo, land cover/dynamics, burned area extent, as well as other key surface biophysical quantities represented by the anisotropic reflectance characteristics of vegetation. In this study, a new retrieval strategy for fine-to-moderate resolution multiangle observations was developed, based on the operational sequence used to retrieve the Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 5 reflectance and BRDF/albedo products. The algorithm makes use of a semiempirical kernel-driven bidirectional reflectance model to provide estimates of intrinsic albedo (i.e., directional-hemispherical reflectance and bihemispherical reflectance), model parameters describing the BRDF, and extensive quality assurance information. The new retrieval strategy was applied to NASA's Cloud Absorption Radiometer (CAR) data acquired during the 2007 Cloud and Land Surface Interaction Campaign (CLASIC) over the well-instrumented Atmospheric Radiation Measurement Program (ARM) Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) site in Oklahoma, USA. For the case analyzed, we obtained approx.1.6 million individual surface bidirectional reflectance factor (BRF) retrievals, from nadir to 75deg off-nadir, and at spatial resolutions ranging from 3 m - 500 m. This unique dataset was used to examine the interaction of the spatial and angular 18 characteristics of a mixed agricultural landscape; and provided the basis for detailed assessments of: (1) the use of a priori knowledge in kernel-driven BRDF model inversions; (2) the interaction between surface reflectance anisotropy and instrument spatial resolution; and (3) the uncertainties that arise when sub-pixel differences in the BRDF are aggregated to a moderate resolution satellite

  3. High-Resolution Rainfall From Radar Reflectivity and Terrestrial Rain Gages for use in Estimating Debris-Flow Susceptibility in the Day Fire, California

    NASA Astrophysics Data System (ADS)

    Hanshaw, M. N.; Schmidt, K. M.; Jorgensen, D. P.; Stock, J. D.

    2007-12-01

    SMART-R also recorded higher seasonal cumulative rainfall than the terrestrial gages, perhaps indicating that not all precipitation reached the ground. For one storm in particular, time-lapse photographs of the ground document snow. This could explain, in part, the discrepancy between storm-specific totals when the rain gages recorded significantly lower totals than the SMART-R. For example, during the storm where snow was observed, the SMART-R recorded a maximum of 66% higher rainfall than the maximum recorded by the gages. Unexpectedly, the highest elevation gage, located in a pre-fire coniferous vegetation community, consistently recorded the lowest precipitation, whereas gages in the lower elevation pre- fire chaparral community recorded the highest totals. The spatial locations of the maximum rainfall inferred by the SMART-R and the terrestrial gages are also offset by 1.6 km, with terrestrial values shifted easterly. The observation that the SMART-R images high rainfall intensities recorded by rain gages suggests that this technology has the ability to quantitatively estimate the spatial distribution over larger areas at a high resolution. Discrepancies on the storm scale, however, need to be investigated further, but we are optimistic that such high resolution data from the SMART-R and the terrestrial gages may lead to the effective application of a prototype debris-flow warning system where such processes put lives at risk.

  4. Estimating Earthquake Magnitude from the Kentucky Bend Scarp in the New Madrid Seismic Zone Using Field Geomorphic Mapping and High-Resolution LiDAR Topography

    NASA Astrophysics Data System (ADS)

    Kelson, K. I.; Kirkendall, W. G.

    2014-12-01

    Recent suggestions that the 1811-1812 earthquakes in the New Madrid Seismic Zone (NMSZ) ranged from M6.8-7.0 versus M8.0 have implications for seismic hazard estimation in the central US. We more accurately identify the location of the NW-striking, NE-facing Kentucky Bend scarp along the northern Reelfoot fault, which is spatially associated with the Lake County uplift, contemporary seismicity, and changes in the Mississippi River from the February 1812 earthquake. We use 1m-resolution LiDAR hillshades and slope surfaces, aerial photography, soil surveys, and field geomorphic mapping to estimate the location, pattern, and amount of late Holocene coseismic surface deformation. We define eight late Holocene to historic fluvial deposits, and delineate younger alluvia that are progressively inset into older deposits on the upthrown, western side of the fault. Some younger, clayey deposits indicate past ponding against the scarp, perhaps following surface deformational events. The Reelfoot fault is represented by sinuous breaks-in-slope cutting across these fluvial deposits, locally coinciding with shallow faults identified via seismic reflection data (Woolery et al., 1999). The deformation pattern is consistent with NE-directed reverse faulting along single or multiple SW-dipping fault planes, and the complex pattern of fluvial deposition appears partially controlled by intermittent uplift. Six localities contain scarps across correlative deposits and allow evaluation of cumulative surface deformation from LiDAR-derived topographic profiles. Displacements range from 3.4±0.2 m, to 2.2±0.2 m, 1.4±0.3 m, and 0.6±0.1 m across four progressively younger surfaces. The spatial distribution of the profiles argues against the differences being a result of along-strike uplift variability. We attribute the lesser displacements of progressively younger deposits to recurrent surface deformation, but do not yet interpret these initial data with respect to possible earthquake

  5. Watershed erosion estimated from a high-resolution sediment core reveals a non-stationary frequency-magnitude relationship and importance of seasonal climate drivers

    NASA Astrophysics Data System (ADS)

    Gavin, D. G.; Colombaroli, D.; Morey, A. E.

    2015-12-01

    The inclusion of paleo-flood events greatly affects estimates of peak magnitudes (e.g., Q100) in flood-frequency analysis. Likewise, peak events also are associated with certain synoptic climatic patterns that vary on all time scales. Geologic records preserved in lake sediments have the potential to capture the non-stationarity in frequency-magnitude relationships, but few such records preserve a continuous history of event magnitudes. We present a 10-meter 2000-yr record from Upper Squaw Lake, Oregon, that contains finely laminated silt layers that reflect landscape erosion events from the 40 km2 watershed. CT-scans of the core (<1 mm resolution) and a 14C-dated chronology yielded a pseudo-annual time series of erosion magnitudes. The most recent 80 years of the record correlates strongly with annual peak stream discharge and road construction. We examined the frequency-magnitude relationship for the entire pre-road period and show that the seven largest events fall above a strongly linear relationship, suggesting a distinct process (e.g., severe fires or earthquakes) operating at low-frequency to generate large-magnitude events. Expressing the record as cumulative sediment accumulation anomalies showed the importance of the large events in "returning the system" to the long-term mean rate. Applying frequency-magnitude analysis in a moving window showed that the Q100 and Q10 of watershed erosion varied by 1.7 and 1.0 orders of magnitude, respectively. The variations in watershed erosion are weakly correlated with temperature and precipitation reconstructions at the decadal to centennial scale. This suggests that dynamics both internal (i.e., sediment production) and external (i.e., earthquakes) to the system, as well as more stochastic events (i.e., single severe wildfires) can at least partially over-ride external climate forcing of watershed erosion at decadal to centennial time scales.

  6. China's land cover and land use change from 1700 to 2005: Estimations from high-resolution satellite data and historical archives

    NASA Astrophysics Data System (ADS)

    Liu, Mingliang; Tian, Hanqin

    2010-09-01

    One of the major limitations in assessing the impacts of human activities on global biogeochemical cycles and climate is a shortage of reliable data on historical land cover and land use change (LCLUC). China had extreme discrepancies in estimating contemporary and historical patterns of LCLUC over the last 3 centuries because of its geographical complexity, long history of land use, and limited national surveys. This study aims to characterize the spatial and temporal patterns of China's LCLUC during 1700-2005 by reconstructing historical gridded data sets from high-resolution satellite data and long-term historical survey data. During this 300 year period, the major characteristics of LCLUC in China have been shrinking forest (decreased by 22%) and expanding cropland (increased by 42%) and urban areas (including urban and rural settlements, factories, quarries, mining, and other built-up land). New cropland areas have come almost equally from both forested and nonforested land. This study also revealed that substantial conversion between forest and woodland can be attributed to forest harvest, forest regeneration, and land degradation. During 1980-2005, LCLUC was characterized by shrinking cropland, expanding urban and forest areas, and large decadal variations on a national level. LCLUC in China showed significant spatial variations during different time periods, which were caused by spatial heterogeneity in vegetation, soils, and climate and regional imbalance in economy development. During 1700-2005, forests shrunk rapidly while croplands expanded in the northeast and southwest of China. During 1980-2005, we found a serious loss of cropland and urban sprawl in the eastern plain, north, and southeast regions of China and a large increase in forested area in the southeast and southwest regions. The reconstructed LCLUC data sets from this study could be used to assess the impacts of land use change on biogeochemical cycles, the water cycle, and the regional

  7. Oxide composite prepared from intermetallic and amorphous Zr67Fe30M3- (M=Au, Pt) alloys and their catalytic activity for CO oxidation

    NASA Astrophysics Data System (ADS)

    Huang, Yung-Han; Wang, Sea-Fue; Kameoka, Satoshi; Miyamoto, Kanji; Tsai, An-Pang

    2017-01-01

    In this study, Zr67Fe30M3 (M=Au, Pt) intermetallic compounds and amorphous alloys were prepared and used as precursors for the synthesis of oxides. Oxidation treatment of the intermetallic compounds at 500 °C followed by X-ray diffraction (XRD) analysis indicated that zirconium and iron were oxidized to ZrO2 and Fe2O3, respectively. In the case of Zr67Fe30M3 amorphous alloys, cubic Zr6Fe3O was observed on the surface of the ribbons after heat treatment at 500 °C in vacuum. Addition of 3% of gold or platinum to the alloy resulted in an increase in the lattice constants of the Zr6Fe3O phase. Grounding the treated ribbons into powders followed by an oxidation treatment at 500 °C in air produced Fe2O3 and ZrO2 supports, where Au and Pt are dissolved in the oxides as confirmed by X-ray photoelectron spectroscopy (XPS). No matter precursors are intermetallics or amorphous phases, the resultant oxides are the same. Although Pt and Au dissolved in the oxides, catalytic activities for CO oxidation were significant improved.

  8. Estimation of reactogenicity of preparations produced on the basis of photoinactivated live vaccines against brucellosis and tularaemia on the organismic level.2. Using the method of speckle-microscopy with high spatial resolution

    NASA Astrophysics Data System (ADS)

    Ulianova, O. V.; Uianov, S. S.; Li, Pengcheng; Luo, Qingming

    2011-04-01

    The method of speckle microscopy was adapted to estimate the reactogenicity of the prototypes of vaccine preparations against extremely dangerous infections. The theory is proposed to describe the mechanism of formation of the output signal from the super-high spatial resolution speckle microscope. The experimental studies show that bacterial suspensions, irradiated in different regimes of inactivation, do not exert negative influence on the blood microcirculations in laboratory animals.

  9. Estimation of reactogenicity of preparations produced on the basis of photoinactivated live vaccines against brucellosis and tularaemia on the organismic level. 2. Using the method of speckle-microscopy with high spatial resolution

    SciTech Connect

    Ulianova, O V; Uianov, S S; Li Pengcheng; Luo Qingming

    2011-04-30

    The method of speckle microscopy was adapted to estimate the reactogenicity of the prototypes of vaccine preparations against extremely dangerous infections. The theory is proposed to describe the mechanism of formation of the output signal from the super-high spatial resolution speckle microscope. The experimental studies show that bacterial suspensions, irradiated in different regimes of inactivation, do not exert negative influence on the blood microcirculations in laboratory animals. (optical technologies in biophysics and medicine)

  10. High resolution analysis of tropical forest fragmentation and its impact on the global carbon cycle

    NASA Astrophysics Data System (ADS)

    Brinck, Katharina; Fischer, Rico; Groeneveld, Jürgen; Lehmann, Sebastian; Dantas de Paula, Mateus; Pütz, Sandro; Sexton, Joseph O.; Song, Danxia; Huth, Andreas

    2017-03-01

    Deforestation in the tropics is not only responsible for direct carbon emissions but also extends the forest edge wherein trees suffer increased mortality. Here we combine high-resolution (30 m) satellite maps of forest cover with estimates of the edge effect and show that 19% of the remaining area of tropical forests lies within 100 m of a forest edge. The tropics house around 50 million forest fragments and the length of the world's tropical forest edges sums to nearly 50 million km. Edge effects in tropical forests have caused an additional 10.3 Gt (2.1-14.4 Gt) of carbon emissions, which translates into 0.34 Gt per year and represents 31% of the currently estimated annual carbon releases due to tropical deforestation. Fragmentation substantially augments carbon emissions from tropical forests and must be taken into account when analysing the role of vegetation in the global carbon cycle.

  11. Integrating High-Resolution Taskable Imagery into a Sensorweb for Automatic Space-Based Monitoring of Flooding in Thailand

    NASA Technical Reports Server (NTRS)

    Chien, Steve; Mclaren, David; Doubleday, Joshua; Tran, Daniel; Tanpipat, Veerachai; Chitradon, Royol; Boonya-aroonnet, Surajate; Thanapakpawin, Porranee; Mandl, Daniel

    2012-01-01

    Several space-based assets (Terra, Aqua, Earth Observing One) have been integrated into a sensorweb to monitor flooding in Thailand. In this approach, the Moderate Imaging Spectrometer (MODIS) data from Terra and Aqua is used to perform broad-scale monitoring to track flooding at the regional level (250m/pixel) and EO-1 is autonomously tasked in response to alerts to acquire higher resolution (30m/pixel) Advanced Land Imager (ALI) data. This data is then automatically processed to derive products such as surface water extent and volumetric water estimates. These products are then automatically pushed to organizations in Thailand for use in damage estimation, relief efforts, and damage mitigation. More recently, this sensorweb structure has been used to request imagery, access imagery, and process high-resolution (several m to 30m), targetable asset imagery from commercial assets including Worldview-2, Ikonos, Radarsat-2, Landsat-7, and Geo-Eye-1. We describe the overall sensorweb framework as well as new workflows and products made possible via these extensions.

  12. Oil slick morphology derived from AVIRIS measurements of the Deepwater Horizon oil spill: Implications for spatial resolution requirements of remote sensors

    USGS Publications Warehouse

    Sun, Shaojie; Hu, Chuanmin; Feng, Lian; Swayze, Gregg A.; Holmes, Jamie; Graettinger, George; MacDonald, Ian R.; Garcia, Oscar; Leifer, Ira

    2016-01-01

    Using fine spatial resolution (~ 7.6 m) hyperspectral AVIRIS data collected over the Deepwater Horizon oil spill in the Gulf of Mexico, we statistically estimated slick lengths, widths and length/width ratios to characterize oil slick morphology for different thickness classes. For all AVIRIS-detected oil slicks (N = 52,100 continuous features) binned into four thickness classes (≤ 50 μm but thicker than sheen, 50–200 μm, 200–1000 μm, and > 1000 μm), the median lengths, widths, and length/width ratios of these classes ranged between 22 and 38 m, 7–11 m, and 2.5–3.3, respectively. The AVIRIS data were further aggregated to 30-m (Landsat resolution) and 300-m (MERIS resolution) spatial bins to determine the fractional oil coverage in each bin. Overall, if 50% fractional pixel coverage were to be required to detect oil with thickness greater than sheen for most oil containing pixels, a 30-m resolution sensor would be needed.

  13. Oil slick morphology derived from AVIRIS measurements of the Deepwater Horizon oil spill: Implications for spatial resolution requirements of remote sensors.

    PubMed

    Sun, Shaojie; Hu, Chuanmin; Feng, Lian; Swayze, Gregg A; Holmes, Jamie; Graettinger, George; MacDonald, Ian; Garcia, Oscar; Leifer, Ira

    2016-02-15

    Using fine spatial resolution (~7.6m) hyperspectral AVIRIS data collected over the Deepwater Horizon oil spill in the Gulf of Mexico, we statistically estimated slick lengths, widths and length/width ratios to characterize oil slick morphology for different thickness classes. For all AVIRIS-detected oil slicks (N=52,100 continuous features) binned into four thickness classes (≤50 μm but thicker than sheen, 50-200 μm, 200-1000 μm, and >1000 μm), the median lengths, widths, and length/width ratios of these classes ranged between 22 and 38 m, 7-11 m, and 2.5-3.3, respectively. The AVIRIS data were further aggregated to 30-m (Landsat resolution) and 300-m (MERIS resolution) spatial bins to determine the fractional oil coverage in each bin. Overall, if 50% fractional pixel coverage were to be required to detect oil with thickness greater than sheen for most oil containing pixels, a 30-m resolution sensor would be needed.

  14. Long-Term Quantitative Precipitation Estimates (QPE) at High Spatial and Temporal Resolution over CONUS: Bias-Adjustment of the Radar-Only National Mosaic and Multi-sensor QPE (NMQ/Q2) Precipitation Reanalysis (2001-2012)

    NASA Astrophysics Data System (ADS)

    Prat, Olivier; Nelson, Brian; Stevens, Scott; Seo, Dong-Jun; Kim, Beomgeun

    2015-04-01

    The processing of radar-only precipitation via the reanalysis from the National Mosaic and Multi-Sensor Quantitative (NMQ/Q2) based on the WSR-88D Next-generation Radar (NEXRAD) network over Continental United States (CONUS) is completed for the period covering from 2001 to 2012. This important milestone constitutes a unique opportunity to study precipitation processes at a 1-km spatial resolution for a 5-min temporal resolution. However, in order to be suitable for hydrological, meteorological and climatological applications, the radar-only product needs to be bias-adjusted and merged with in-situ rain gauge information. Several in-situ datasets are available to assess the biases of the radar-only product and to adjust for those biases to provide a multi-sensor QPE. The rain gauge networks that are used such as the Global Historical Climatology Network-Daily (GHCN-D), the Hydrometeorological Automated Data System (HADS), the Automated Surface Observing Systems (ASOS), and the Climate Reference Network (CRN), have different spatial density and temporal resolution. The challenges related to incorporating non-homogeneous networks over a vast area and for a long-term record are enormous. Among the challenges we are facing are the difficulties incorporating differing resolution and quality surface measurements to adjust gridded estimates of precipitation. Another challenge is the type of adjustment technique. The objective of this work is threefold. First, we investigate how the different in-situ networks can impact the precipitation estimates as a function of the spatial density, sensor type, and temporal resolution. Second, we assess conditional and un-conditional biases of the radar-only QPE for various time scales (daily, hourly, 5-min) using in-situ precipitation observations. Finally, after assessing the bias and applying reduction or elimination techniques, we are using a unique in-situ dataset merging the different RG networks (CRN, ASOS, HADS, GHCN-D) to

  15. High-resolution digital elevation model from tri-stereo Pleiades-1 satellite imagery for lava flow volume estimates at Fogo Volcano

    NASA Astrophysics Data System (ADS)

    Bagnardi, Marco; González, Pablo J.; Hooper, Andrew

    2016-06-01

    Resolving changes in topography through time using accurate high-resolution digital elevation models (DEMs) is key to understanding active volcanic processes. For the first time in a volcanic environment, we utilize very high-resolution tri-stereo optical imagery acquired by the Pleiades-1 satellite constellation and generate a 1 m resolution DEM of Fogo Volcano, Cape Verde -- the most active volcano in the Eastern Atlantic region. Point cloud density is increased by a factor of 6.5 compared to conventional stereo imagery, and the number of 1 m2 pixels with no height measurements is reduced by 43%. We use the DEM to quantify topographic changes associated with the 2014-2015 eruption at Fogo. Height differences between the posteruptive Pleiades-1 DEM and the preeruptive topography from TanDEM-X give a lava flow volume of 45.83 ± 0.02 × 106 m3, emplaced over an area of 4.8 km2 at a mean rate of 6.8 m3 s-1.

  16. RAVEN - High-resolution Mapping of Venus within a Discovery Mission Budget

    NASA Astrophysics Data System (ADS)

    Sharpton, V. L.; Herrick, R. R.; Rogers, F.; Waterman, S.

    2009-12-01

    It has been more than 15 years since the Magellan mission mapped Venus with S-band synthetic aperture radar (SAR) images at ~100-m resolution. Advances in radar technology are such that current Earth-orbiting SAR instruments are capable of providing images at meter-scale resolution. RAVEN (RAdar at VENus) is a mission concept that utilizes the instrument developed for the RADARSAT Constellation Mission (RCM) to map Venus in an economical, highly capable, and reliable way. RCM relies on a C-band SAR that can be tuned to generate images at a wide variety of resolutions and swath widths, ranging from ScanSAR mode (broad swaths at 30-m resolution) to strip-map mode (resolutions as fine as 3 m), as well as a spotlight mode that can image patches at 1-m resolution. In particular, the high-resolution modes allow the landing sites of previous missions to be pinpointed and characterized. Repeat-pass interferometric SAR (InSAR) and stereo radargrammetry provide options for constraining topography to better than 100-m horizontal and 10-m vertical resolution. InSAR also provides the potential for detecting surface deformation at centimeter precision. Performing InSAR requires precise knowledge and control of the orbital geometry, and for this reason a 600-km circular polar orbit is favored. This configuration causes the equatorial nadir point to move ~9 km per orbit. Considering both ascending and descending passes, the spacecraft will pass over every point on the planet in half a Venus day (~4 Earth months). The ability to transmit data back to Earth via the Deep Space Network is the primary limiting factor on the volume of data that can be collected. Our current estimates indicate that within an imaging cycle of one Venus day we can image 20-30 percent of the planet at 20-30-m resolution and several percent at 3-5 m resolution. These figures compare favorably to the coverage provided by recent imaging systems orbiting Mars. Our strategy calls for the first cycle of coverage

  17. High flow-resolution for mobility estimation in 2D-ENMR of proteins using maximum entropy method (MEM-ENMR).

    PubMed

    Thakur, Sunitha B; He, Qiuhong

    2006-11-01

    Multidimensional electrophoretic NMR (nD-ENMR) is a potentially powerful tool for structural characterization of co-existing proteins and protein conformations. By applying a DC electric field pulse, the electrophoretic migration rates of different proteins were detected experimentally in a new dimension of electrophoretic flow. The electrophoretic mobilities were employed to differentiate protein signals. In U-shaped ENMR sample chambers, individual protein components in a solution mixture followed a cosinusoidal electrophoretic interferogram as a function of its unique electrophoretic migration rate. After Fourier transformation in the electrophoretic flow dimension, the protein signals were resolved at different resonant frequencies proportional to their electrophoretic mobilities. Currently, the mobility resolution of the proteins in the electrophoretic flow dimension is limited by severe truncations of the electrophoretic interferograms due to the finite electric field strength available before the onset of heat-induced convection. In this article, we present a successful signal processing method, the Burg's maximum entropy method (MEM), to analyze the truncated ENMR signals (MEM-ENMR). Significant enhancement in flow resolution was demonstrated using two-dimensional ENMR of two protein samples: a lysozyme solution and a solution mixture of bovine serum albumin (BSA) and ubiquitin. The electrophoretic mobilities of lysozyme, BSA and ubiquitin were measured from the MEM analysis as 7.5x10(-5), 1.9x10(-4) and 8.7x10(-5) cm2 V-1 s-1, respectively. Results from computer simulations confirmed a complete removal of truncation artifacts in the MEM-ENMR spectra with 3- to 6-fold resolution enhancement.

  18. Long-Term Large-Scale Bias-Adjusted Precipitation Estimates at High Spatial and Temporal Resolution Derived from the National Mosaic and Multi-Sensor QPE (NMQ/Q2) Precipitation Reanalysis over CONUS

    NASA Astrophysics Data System (ADS)

    Prat, O. P.; Nelson, B. R.; Stevens, S. E.; Seo, D. J.; Kim, B.

    2014-12-01

    The processing of radar-only precipitation via the reanalysis from the National Mosaic and Multi-Sensor Quantitative (NMQ/Q2) based on the WSR-88D Next-generation Radar (Nexrad) network over Continental United States (CONUS) is nearly completed for the period covering from 2000 to 2012. This important milestone constitutes a unique opportunity to study precipitation processes at a 1-km spatial resolution for a 5-min temporal resolution. However, in order to be suitable for hydrological, meteorological and climatological applications, the radar-only product needs to be bias-adjusted and merged with in-situ rain gauge information. Rain gauge networks such as the Hydrometeorological Automated Data System (HADS), the Automated Surface Observing Systems (ASOS), the Climate Reference Network (CRN), and the Global Historical Climatology Network - Daily (GHCN-D) are used to adjust for those biases and to merge with the radar only product to provide a multi-sensor estimate. The challenges related to incorporating non-homogeneous networks over a vast area and for a long-term record are enormous. Among the challenges we are facing are the difficulties incorporating differing resolution and quality surface measurements to adjust gridded estimates of precipitation. Another challenge is the type of adjustment technique. After assessing the bias and applying reduction or elimination techniques, we are investigating the kriging method and its variants such as simple kriging (SK), ordinary kriging (OK), and conditional bias-penalized Kriging (CBPK) among others. In addition we hope to generate estimates of uncertainty for the gridded estimate. In this work the methodology is presented as well as a comparison between the radar-only product and the final multi-sensor QPE product. The comparison is performed at various time scales from the sub-hourly, to annual. In addition, comparisons over the same period with a suite of lower resolution QPEs derived from ground based radar

  19. Winter wheat yield estimation based on multi-source medium resolution optical and radar imaging data and the AquaCrop model using the particle swarm optimization algorithm

    NASA Astrophysics Data System (ADS)

    Jin, Xiuliang; Li, Zhenhai; Yang, Guijun; Yang, Hao; Feng, Haikuan; Xu, Xingang; Wang, Jihua; Li, Xinchuan; Luo, Juhua

    2017-04-01

    Timely and accurate estimation of winter wheat yield at a regional scale is crucial for national food policy and security assessments. Near-infrared reflectance is not sensitive to the leaf area index (LAI) and biomass of winter wheat at medium to high canopy cover (CC), and most of the vegetation indices displayed saturation phenomenon. However, LAI and biomass at medium to high CC can be efficiently estimated using imaging data from radar with stronger penetration, such as RADARSAT-2. This study had the following three objectives: (i) to combine vegetation indices based on our previous studies for estimating CC and biomass for winter wheat using HJ-1A/B and RADARSAT-2 imaging data; (ii) to combine HJ-1A/B and RADARSAT-2 imaging data with the AquaCrop model using the particle swarm optimization (PSO) algorithm to estimate winter wheat yield; and (iii) to compare the results from the assimilation of HJ-1A/B + RADARSAT-2 imaging data, HJ-1A/B imaging data, and RADARSAT-2 imaging data into the AquaCrop model using the PSO algorithm. Remote sensing data and concurrent LAI, biomass, and yield of sample fields were acquired in Yangling District, Shaanxi, China, during the 2014 winter wheat growing season. The PSO optimization algorithm was used to integrate the AquaCrop model and remote sensing data for yield estimation. The modified triangular vegetation index 2 (MTVI2) × radar vegetation index (RVI) and the enhanced vegetation index (EVI) × RVI had good relationships with CC and biomass, respectively. The results indicated that the predicted and measured yield (R2 = 0.31 and RMSE = 0.94 ton/ha) had agreement when the estimated CC from the HJ-1A/B and RADARSAT-2 data was used as the dynamic input variable for the AquaCrop model. When the estimated biomass from the HJ-1A/B and RADARSAT-2 data was used as the dynamic input variable for the AquaCrop model, the predicted yield showed agreement with the measured yield (R2 = 0.42 and RMSE = 0.81 ton/ha). These results show

  20. Heat transfer at a sapphire – indium interface in the 30 mK – 300 mK temperature range

    NASA Astrophysics Data System (ADS)

    Liberadzka, J.; Koettig, T.; Bremer, J.; van der Post, C. C. W.; ter Brake, H. J. M.

    2017-02-01

    Within the framework of the AEgIS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy) project a direct measurement of the Earth’s gravitational acceleration on antihydrogen will be carried out. In order to obtain satisfactory precision of the measurement, the thermal movement of the particles should be reduced. Therefore a Penning trap, which is used to trap antiprotons and create antihydrogen, will be placed on a mixing chamber of an especially designed dilution refrigerator. The trap consists of 10 electrodes, which need to be electrically insulated, but thermally anchored. To ensure that the trap remains at a temperature below 100 mK, the heat transfer at the metallic-dielectric boundary is investigated. A copper – indium – sapphire – indium – copper sandwich setup was mounted on the CERN Cryolab dilution refrigerator. Keeping the mixing chamber at a constant low temperature in the range of 30 mK to 300 mK, steady-state measurements with indium in normal conducting and superconducting states have been performed. Obtained results along with a precise description of our setup are presented.

  1. Gene therapy approach to FAP: in vivo influence of T119M in TTR deposition in a transgenic V30M mouse model.

    PubMed

    Batista, A R; Gianni, D; Ventosa, M; Coelho, A V; Almeida, M R; Sena-Esteves, M; Saraiva, M J

    2014-12-01

    Familial amyloidotic polyneuropathy (FAP) is a neurodegenerative disorder characterized by extracellular deposition of amyloid fibrils composed by mutated transthyretin (TTR) mainly in the peripheral nervous system. At present, liver transplantation is still the standard treatment to halt the progression of clinical symptoms in FAP, but new therapeutic strategies are emerging, including the use of TTR stabilizers. Here we propose to establish a new gene therapy approach using adeno-associated virus (AAV) vectors to deliver the trans-suppressor TTR T119M variant to the liver of transgenic TTR V30M mice at different ages. This TTR variant is known for its ability to stabilize the tetrameric protein. Analysis of the gastrointestinal tract of AAV-treated animals revealed a significant reduction in deposition of TTR non-fibrillar aggregates in as much as 34% in stomach and 30% in colon, as well as decreased levels of biomarkers associated with TTR deposition, namely the endoplasmic reticulum stress marker BiP and the extracellular matrix protein MMP-9. Moreover, we showed with different studies that our approach leads to an increase in tetrameric and more stable forms of TTR, in favor of destabilized monomers. Altogether our data suggest the possibility to use this gene therapy approach in a prophylactic manner to prevent FAP pathology.

  2. Death anxiety and symbolic immortality in relatives at risk for familial amyloid polyneuropathy type I (FAP I, ATTR V30M).

    PubMed

    Santos, Paula I; Figueiredo, Eurico; Gomes, Inês; Sequeiros, Jorge

    2010-12-01

    This study is an investigation of the impact of familial amyloid polyneuropathy type I (FAP I, ATTR V30M) on death anxiety and symbolic immortality. Templer and Drolet's scales were administered to 524 individuals: (1) 84 relatives at risk, (2) 92 relatives not at risk for FAP I; and (3) a control group (n = 348) with no known hereditary disease in their families. At-risk relatives had, on average, a higher score for death anxiety and a lower score for symbolic immortality, than either those not-at-risk or controls. There were no significant differences in scores on either measure for those not-at-risk versus controls. Being at risk increases death anxiety and threatens the sense of symbolic immortality and psychosocial wellbeing. This may be true for other serious hereditary disorders as well. Genetic counsellors should become familiar with these concepts, feel comfortable initiating discussions about death with their patients, and be able to identify and reinforce their patients' and family members' sense of symbolic immortality.

  3. A multi-resolution assessment of the Community Multiscale Air Quality (CMAQ) model v4.7 wet deposition estimates for 2002-2006

    NASA Astrophysics Data System (ADS)

    Appel, K. W.; Foley, K. M.; Bash, J. O.; Pinder, R. W.; Dennis, R. L.; Allen, D. J.; Pickering, K.

    2011-05-01

    This paper examines the operational performance of the Community Multiscale Air Quality (CMAQ) model simulations for 2002-2006 using both 36-km and 12-km horizontal grid spacing, with a primary focus on the performance of the CMAQ model in predicting wet deposition of sulfate (SO4=), ammonium (NH4+) and nitrate (NO3-). Performance of the wet deposition estimates from the model is determined by comparing CMAQ predicted concentrations to concentrations measured by the National Acid Deposition Program (NADP), specifically the National Trends Network (NTN). For SO4= wet deposition, the CMAQ model estimates were generally comparable between the 36-km and 12-km simulations for the eastern US, with the 12-km simulation giving slightly higher estimates of SO4= wet deposition than the 36-km simulation on average. The result is a slightly larger normalized mean bias (NMB) for the 12-km simulation; however both simulations had annual biases that were less than ±15 % for each of the five years. The model estimated SO4= wet deposition values improved when they were adjusted to account for biases in the model estimated precipitation. The CMAQ model underestimates NH4+ wet deposition over the eastern US, with a slightly larger underestimation in the 36-km simulation. The largest underestimations occur in the winter and spring periods, while the summer and fall have slightly smaller underestimations of NH4+ wet deposition. The underestimation in NH4+ wet deposition is likely due in part to the poor temporal and spatial representation of ammonia (NH3) emissions, particularly those emissions associated with fertilizer applications and NH3 bi-directional exchange. The model performance for estimates of NO3- wet deposition are mixed throughout the year, with the model largely underestimating NO3- wet deposition in the spring and summer in the eastern US, while the model has a relatively small bias in the fall and winter. Model estimates of NO3- wet deposition tend to be slightly

  4. Fusing enhanced radar precipitation, in-situ hydrometeorological measurements and airborne LIDAR snowpack estimates in a hyper-resolution hydrologic model to improve seasonal water supply forecasts

    NASA Astrophysics Data System (ADS)

    Gochis, D. J.; Busto, J.; Howard, K.; Mickey, J.; Deems, J. S.; Painter, T. H.; Richardson, M.; Dugger, A. L.; Karsten, L. R.; Tang, L.

    2015-12-01

    Scarcity of spatially- and temporally-continuous observations of precipitation and snowpack conditions in remote mountain watersheds results in fundamental limitations in water supply forecasting. These limitationsin observational capabilities can result in strong biases in total snowmelt-driven runoff amount, the elevational distribution of runoff, river basin tributary contributions to total basin runoff and, equally important for water management, the timing of runoff. The Upper Rio Grande River basin in Colorado and New Mexico is one basin where observational deficiencies are hypothesized to have significant adverse impacts on estimates of snowpack melt-out rates and on water supply forecasts. We present findings from a coordinated observational-modeling study within Upper Rio Grande River basin whose aim was to quanitfy the impact enhanced precipitation, meteorological and snowpack measurements on the simulation and prediction of snowmelt driven streamflow. The Rio Grande SNOwpack and streamFLOW (RIO-SNO-FLOW) Prediction Project conducted enhanced observing activities during the 2014-2015 water year. Measurements from a gap-filling, polarimetric radar (NOXP) and in-situ meteorological and snowpack measurement stations were assimilated into the WRF-Hydro modeling framework to provide continuous analyses of snowpack and streamflow conditions. Airborne lidar estimates of snowpack conditions from the NASA Airborne Snow Observatory during mid-April and mid-May were used as additional independent validations against the various model simulations and forecasts of snowpack conditions during the melt-out season. Uncalibrated WRF-Hydro model performance from simulations and forecasts driven by enhanced observational analyses were compared against results driven by currently operational data inputs. Precipitation estimates from the NOXP research radar validate significantly better against independent in situ observations of precipitation and snow-pack increases

  5. Synergistic using medium-resolution and high-resolution remote sensing imagery to extract impervious surface for Dianci Basin

    NASA Astrophysics Data System (ADS)

    Hong, Liang; Yang, Kun; Deng, Ming; Liu, Cun

    2014-03-01

    The knowledge of impervious surfaces, especially the magnitude, location, geometry, spatial pattern of impervious surfaces, is significant to urban ecosystem studies, including urban hydrology, urban climate, land use planning and resource management.Impervious surface area (ISA) is considered a key indicator of environmental quality and can be used to address complex urban environmental issues, particularly those related to the health of urban watersheds. ISA is also an indicator of non-point source pollution or polluted runoff. Remote sensing offers a consistent framework for representing spatial patterns and rates of urbanization over time through accurate observations of impervious surface area. Most of the existing methods of extracting impervious surface based on remote sensing concentrate on an urban scale, but the rapid and accurate methods of extracting impervious surfaces in a basin scale are nearly nonexistent in China and abroad. In recent years,with the rapid urbanization especially surrounding the Dianchi water body, the impervious surface coverage rate also grows rapidly and results in severe degradation of basin water environment within Dianchi watershed. In this study, we developed an approach to extract impervious surface for Dianci Basin by synergistic using medium-resolution and high-resolution remote sensing imagery. Subpixel percent impervious surfaces at Thematic Mapper (TM) images were mapped using the classification and regression tree(CART) algorithm. Sub-pixel impervious surfaces at 30m resolution were mapped in this study area through regression tree models. The estimated ISA results were evaluated through independent ISA reference data derived from high resolution QuickBird. The results prove the suitability of the approach for a widely automated and mapping of impervious surfaces in a basin scale.

  6. Glioblastoma brain tumours: estimating the time from brain tumour initiation and resolution of a patient survival anomaly after similar treatment protocols.

    PubMed

    Murray, J D

    2012-01-01

    A practical mathematical model for glioblastomas (brain tumours), which incorporates the two key parameters of tumour growth, namely the cancer cell diffusion and the cell proliferation rate, has been shown to be clinically useful and predictive. Previous studies explain why multifocal recurrence is inevitable and show how various treatment scenarios have been incorporated in the model. In most tumours, it is not known when the cancer started. Based on patient in vivo parameters, obtained from two brain scans, it is shown how to estimate the time, after initial detection, when the tumour started. This is an input of potential importance in any future controlled clinical study of any connection between cell phone radiation and brain tumour incidence. It is also used to estimate more accurately survival times from detection. Finally, based on patient parameters, the solution of the model equation of the tumour growth helps to explain why certain patients live longer than others after similar treatment protocols specifically surgical resection (removal) and irradiation.

  7. Investigation of rat bone fracture healing using pulsed 1.5 MHz, 30 mW/cm(2) burst ultrasound--axial distance dependency.

    PubMed

    Fung, Chak-Hei; Cheung, Wing-Hoi; Pounder, Neill M; de Ana, F Javier; Harrison, Andrew; Leung, Kwok-Sui

    2014-03-01

    This study investigated the effect of LIPUS on fracture healing when fractures were exposed to ultrasound at three axial distances: z=0 mm, 60 mm, and 130 mm. We applied LIPUS to rat fracture at these three axial distances mimicking the exposure condition of human fractures at different depths under the soft tissue. Measurement of LIPUS shows pressure variations in near field (nearby transducer); uniform profile was found beyond it (far field). We asked whether different positions of the fracture within the ultrasound field cause inconsistent biological effect during the healing process. Closed femoral fractured Sprague-Dawley rats were randomized into control, near-field (0mm), mid-near field (60 mm) or far-field (130 mm) groups. Daily LIPUS treatment (plane, but apodized source, see details in the text; 2.2 cm in diameter; 1.5 MHz sine waves repeating at 1 kHz PRF; spatial average temporal average intensity, ISATA=30 mW/cm(2)) was given to fracture site at the three axial distances. Weekly radiographs and endpoint microCT, histomorphometry, and mechanical tests were performed. The results showed that the 130 mm group had the highest tissue mineral density; and significantly higher mechanical properties than control at week 4. The 60 mm and 0 mm groups had significantly higher (i.e. p<0.05) woven bone percentage than control group in radiological, microCT and histomorphometry measurements. In general, LIPUS at far field augmented callus mineralization and mechanical properties; while near field and mid-near field enhanced woven bone formation. Our results indicated the therapeutic effect of LIPUS is dependent on the axial distance of the ultrasound beam. Therefore, the depth of fracture under the soft tissue affects the biological effect of LIPUS. Clinicians have to be aware of the fracture depth when LIPUS is applied transcutaneously.

  8. Forest Aboveground Biomass Estimation in the Greater Mekong, Subregion and Russian Siberia

    NASA Astrophysics Data System (ADS)

    Pang, Yong; Li, Zengyuan; Sun, Gouqing; Zhang, Zhiyu; Schmullius, Christiane; Meng, Shili; Ma, Zhenyu; Lu, Hao; Li, Shiming; Liu, Qingwang; Bai, Lina; Tian, Xin

    2016-08-01

    Forests play a vital role in sustainable development and provide a range of economic, social and environmental benefits, including essential ecosystem services such as climate change mitigation and adaptation. We summarized works in forest aboveground biomass estimation in Greater Mekong Subregion (GMS) and Russian Siberia (RuS). Both regions are rich in forest resources. These mapping and estimation works were based on multiple-source remote sensing data and some field measurements. Biomass maps were generated at 500 m and 30 m pixel size for RuS and GMS respectively. With the available of the 2015 PALSAR-2 mosaic at 25 m spacing, Sentinel-2 data at 20 m, we will work on the biomass mapping and dynamic study at higher spatial resolution.

  9. Nano silver and nano zinc-oxide in surface waters – Exposure estimation for Europe at high spatial and temporal resolution

    PubMed Central

    Dumont, Egon; Johnson, Andrew C.; Keller, Virginie D.J.; Williams, Richard J.

    2015-01-01

    Nano silver and nano zinc-oxide monthly concentrations in surface waters across Europe were modeled at ∼6 × 9 km spatial resolution. Nano-particle loadings from households to rivers were simulated considering household connectivity to sewerage, sewage treatment efficiency, the spatial distribution of sewage treatment plants, and their associated populations. These loadings were used to model temporally varying nano-particle concentrations in rivers, lakes and wetlands by considering dilution, downstream transport, water evaporation, water abstraction, and nano-particle sedimentation. Temporal variability in concentrations caused by weather variation was simulated using monthly weather data for a representative 31-year period. Modeled concentrations represent current levels of nano-particle production. Two scenarios were modeled. In the most likely scenario, half the river stretches had long-term average concentrations exceeding 0.002 ng L−1 nano silver and 1.5 ng L−1 nano zinc oxide. In 10% of the river stretches, these concentrations exceeded 0.18 ng L−1 and 150 ng L−1, respectively. Predicted concentrations were usually highest in July. PMID:25463731

  10. Pike and salmon as sister taxa: detailed intraclade resolution and divergence time estimation of Esociformes + Salmoniformes based on whole mitochondrial genome sequences.

    PubMed

    Campbell, Matthew A; López, J Andrés; Sado, Tetsuya; Miya, Masaki

    2013-11-01

    The increasing number of taxa and loci in molecular phylogenetic studies of basal euteleosts has brought stability in a controversial area. A key emerging aspect to these studies is a sister Esociformes (pike) and Salmoniformes (salmon) relationship. We evaluate mitochondrial genome support for a sister Esociformes and Salmoniformes hypothesis by surveying many potential outgroups for these taxa, employing multiple phylogenetic approaches, and utilizing a thorough sampling scheme. Secondly, we conduct a simultaneous divergence time estimation and phylogenetic inference in a Bayesian framework with fossil calibrations focusing on relationships within Esociformes+Salmoniformes. Our dataset supports a sister relationship between Esociformes and Salmoniformes; however the nearest relatives of Esociformes+Salmoniformes are inconsistent among analyses. Within the order Esociformes, we advocate for a single family, Esocidae. Subfamily relationships within Salmonidae are poorly supported as Salmoninae sister to Thymallinae+Coregoninae.

  11. The limits of ultrahigh-resolution x-ray mapping: estimating uncertainties in thin-film and interface structures determined by phase retrieval methods

    SciTech Connect

    Zhou H.; Pindak R.; Clarke, R.; Steinberg, D.NM.; Yacoby, Y.

    2012-04-25

    Capturing subtle details at the sub-Angstrom level is key to understanding the structural basis of many intriguing interfacial phenomena in epitaxial thin films and nanostructures. X-ray phase retrieval methods are ideally suited to this task but the usual approaches for determination of uncertainties, based on refining a parametrized model, are not applicable in this case. Here we describe a method to estimate the uncertainties of the system electron density, obtained by phase retrieval, and of parameters of interest obtained from it. The method is based on the bootstrap approach and it can be generally applied to surface x-ray scattering data. Several examples are given which illustrate the method's utility in determining uncertainties arising from random and systematic errors. The approach also provides a quantitative measure of the validity of structural solutions obtained by phase retrieval methods.

  12. The limits of ultrahigh-resolution x-ray mapping: estimating uncertainties in thin-film and interface structures determined by phase retrieval methods

    NASA Astrophysics Data System (ADS)

    Zhou, Hua; Pindak, Ron; Clarke, Roy; Steinberg, David M.; Yacoby, Yizhak

    2012-05-01

    Capturing subtle details at the sub-Angstrom level is key to understanding the structural basis of many intriguing interfacial phenomena in epitaxial thin films and nanostructures. X-ray phase retrieval methods are ideally suited to this task but the usual approaches for determination of uncertainties, based on refining a parametrized model, are not applicable in this case. Here we describe a method to estimate the uncertainties of the system electron density, obtained by phase retrieval, and of parameters of interest obtained from it. The method is based on the bootstrap approach and it can be generally applied to surface x-ray scattering data. Several examples are given which illustrate the method's utility in determining uncertainties arising from random and systematic errors. The approach also provides a quantitative measure of the validity of structural solutions obtained by phase retrieval methods.

  13. Automated drumlin shape and volume estimation using high resolution LiDAR imagery (Curvature Based Relief Separation): A test from the Wadena Drumlin Field, Minnesota

    NASA Astrophysics Data System (ADS)

    Yu, Peter; Eyles, Nick; Sookhan, Shane

    2015-10-01

    Resolving the origin(s) of drumlins and related megaridges in areas of megascale glacial lineations (MSGL) left by paleo-ice sheets is critical to understanding how ancient ice sheets interacted with their sediment beds. MSGL is now linked with fast-flowing ice streams but there is a broad range of erosional and depositional models. Further progress is reliant on constraining fluxes of subglacial sediment at the ice sheet base which in turn is dependent on morphological data such as landform shape and elongation and most importantly landform volume. Past practice in determining shape has employed a broad range of geomorphological methods from strictly visualisation techniques to more complex semi-automated and automated drumlin extraction methods. This paper reviews and builds on currently available visualisation, semi-automated and automated extraction methods and presents a new, Curvature Based Relief Separation (CBRS) technique; for drumlin mapping. This uses curvature analysis to generate a base level from which topography can be normalized and drumlin volume can be derived. This methodology is tested using a high resolution (3 m) LiDAR elevation dataset from the Wadena Drumlin Field, Minnesota, USA, which was constructed by the Wadena Lobe of the Laurentide Ice Sheet ca. 20,000 years ago and which as a whole contains 2000 drumlins across an area of 7500 km2. This analysis demonstrates that CBRS provides an objective and robust procedure for automated drumlin extraction. There is strong agreement with manually selected landforms but the method is also capable of resolving features that were not detectable manually thereby considerably expanding the known population of streamlined landforms. CBRS provides an effective automatic method for visualisation of large areas of the streamlined beds of former ice sheets and for modelling sediment fluxes below ice sheets.

  14. Evaluating The National Land Cover Database Tree Canopy and Impervious Cover Estimates Across the Conterminous United States: A Comparison with Photo-Interpreted Estimates

    PubMed Central

    Greenfield, Eric J.

    2010-01-01

    The 2001 National Land Cover Database (NLCD) provides 30-m resolution estimates of percentage tree canopy and percentage impervious cover for the conterminous United States. Previous estimates that compared NLCD tree canopy and impervious cover estimates with photo-interpreted cover estimates within selected counties and places revealed that NLCD underestimates tree and impervious cover. Based on these previous results, a wall-to-wall comprehensive national analysis was conducted to determine if and how NLCD derived estimates of tree and impervious cover varies from photo-interpreted values across the conterminous United States. Results of this analysis reveal that NLCD significantly underestimates tree cover in 64 of the 65 zones used to create the NCLD cover maps, with a national average underestimation of 9.7% (standard error (SE) = 1.0%) and a maximum underestimation of 28.4% in mapping zone 3. Impervious cover was also underestimated in 44 zones with an average underestimation of 1.4% (SE = 0.4%) and a maximum underestimation of 5.7% in mapping zone 56. Understanding the degree of underestimation by mapping zone can lead to better estimates of tree and impervious cover and a better understanding of the potential limitations associated with NLCD cover estimates. PMID:20676888

  15. The IRAM-30 m line survey of the Horsehead PDR. III. High abundance of complex (iso-)nitrile molecules in UV-illuminated gas

    NASA Astrophysics Data System (ADS)

    Gratier, P.; Pety, J.; Guzmán, V.; Gerin, M.; Goicoechea, J. R.; Roueff, E.; Faure, A.

    2013-09-01

    obtained with the IRAM-30 m telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).Appendices are available in electronic form at http://www.aanda.org

  16. Comparison of separations of fatty acids from fish products using a 30-m Supelcowax-10 and a 100-m SP-2560 column.

    PubMed

    Santercole, Viviana; Delmonte, Pierluigi; Kramer, John K G

    2012-03-01

    Commercial fish oils and foods containing fish may contain trans and/or isomerized fatty acids (FA) produced during processing or as part of prepared foods. The current American Oil Chemists' Society (AOCS) official method for marine oils (method Ce 1i-07) is based on separation by use of poly(ethylene glycol) (PEG) columns, for example Supelcowax-10 or equivalent, which do not resolve most unsaturated FA geometric isomers. Highly polar 100-m cyanopropyl siloxane (CPS) columns, for example SP-2560 and CP Sil 88 are recommended for separation of geometric FA isomers. Complementary separations were achieved by use of two different elution temperature programs with the same CPS column. This study is the first direct comparison of the separations achieved by use of 30-m Supelcowax-10 and 100-m SP-2560 columns for fatty acid methyl esters (FAME) prepared from the same fish oil and fish muscle sample. To simplify the identification of the FA in these fish samples, FA were fractionated on the basis of the number and type of double bonds by silver-ion solid-phase extraction (Ag⁺-SPE) before GC analysis. The results showed that a combination of the three GC separations was necessary to resolve and identify most of the unsaturated FA, FA isomers, and other components of fish products, for example phytanic and phytenic acids. Equivalent chain length (ECL) values of most FAME in fish were calculated from the separations achieved by use of both GC columns; the values obtained were shown to be consistent with previously reported values for the Supelcowax-10 column. ECL values were also calculated for the FA separated on the SP-2560 column. The calculated ECL values were equally valid under isothermal and temperature-programmed elution GC conditions, and were valuable for confirmation of the identity of several unsaturated FAME in the fish samples. When analyzing commercially prepared fish foods, deodorized marine oils, or foods fortified with marine oils it is strongly

  17. Analysis of selected designer benzodiazepines by UHPLC with high-resolution time-of-flight mass spectrometry and the estimation of their partition coefficients by micellar electrokinetic chromatography.

    PubMed

    Tomková, Jana; Švidrnoch, Martin; Maier, Vítězslav; Ondra, Peter

    2017-03-07

    A new ultra high performance liquid chromatography with electrospray ionization time-of-flight mass spectrometry method for the selective and sensitive separation, identification and determination of selected designer benzodiazepines (namely, pyrazolam, phenazepam, etizolam, flubromazepam, diclazepam, deschloroetizolam, bentazepam, nimetazepam and flubromazolam) in human serum was developed. The separation of the studied designer benzodiazepines was achieved on C18 chromatographic column using gradient elution within 6 min without any significant matrix interferences. Liquid-liquid extraction with butyl acetate was applied for serum samples clean-up and preconcentration of studied designer benzodiazepines. The method was validated in terms of linearity, limit of detection, limit of quantification, matrix effects, specificity, precision, accuracy, recovery and sample stability. The limit of detection values were in range 0.10-0.15 ng/mL. The method was applied on spiked serum sample to demonstrate its applicability for systematic toxicology analysis. Furthermore, a capillary chromatographic method with micellar electrokinetic chromatography was used for the estimation of partition coefficients of studied designer benzodiazepines as important parameters to evaluate their pharmacological and toxicological properties. This article is protected by copyright. All rights reserved.

  18. Resolution Enhancement of Multilook Imagery

    SciTech Connect

    Galbraith, Amy E.

    2004-07-01

    This dissertation studies the feasibility of enhancing the spatial resolution of multi-look remotely-sensed imagery using an iterative resolution enhancement algorithm known as Projection Onto Convex Sets (POCS). A multi-angle satellite image modeling tool is implemented, and simulated multi-look imagery is formed to test the resolution enhancement algorithm. Experiments are done to determine the optimal con guration and number of multi-angle low-resolution images needed for a quantitative improvement in the spatial resolution of the high-resolution estimate. The important topic of aliasing is examined in the context of the POCS resolution enhancement algorithm performance. In addition, the extension of the method to multispectral sensor images is discussed and an example is shown using multispectral confocal fluorescence imaging microscope data. Finally, the remote sensing issues of atmospheric path radiance and directional reflectance variations are explored to determine their effect on the resolution enhancement performance.

  19. High-Resolution Measurements of Middle Ear Gas Volume Changes in the Rabbit Enables Estimation of its Mucosal CO2 Conductance

    PubMed Central

    Dirckx, Joris J.J.; Ar, Amos

    2006-01-01

    {CO}}_{2} $$\\end{document} data was also made in five additional cases where secretion of fluids from the lining of the ear canal was observed. In these cases \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\mathop V\\limits^ \\bullet }_{{\\text{i}}} {\\text{CO}}_{2} $$\\end{document} was 245 ± 142 μL·h−1. No differences were found between results obtained in the three groups. Thus, an overall mean value of \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\mathop V\\limits^ \\bullet }_{{\\text{i}}} {\\text{CO}}_{2} $$\\end{document} of 305 ± 131 μL·h−1 (n = 16) was calculated. An effective coefficient of conductance of CO2 (G2) between the mucosal circulation and the ME gas cavity of the New Zealand White rabbit was estimated to be ≈0.05 μL (h·Pa)−1 and compared to the G2 estimated for humans in a different study. PMID:16724292

  20. Application of non-linear optimization methods to the estimation of multivariate curve resolution solutions and of their feasible band boundaries in the investigation of two chemical and environmental simulated data sets.

    PubMed

    Tauler, R

    2007-07-09

    Although alternating least squares algorithms have revealed extremely useful and flexible to solve multivariate curve resolution problems, other approaches based on non-linear optimization algorithms using non-linear constraints are possible. Once the subspaces defined by PCA solutions are identified, appropriate rotation and perturbation of these solutions can produce solutions fulfilling the constraints obeyed by the physical nature of the investigated systems. In order to perform such a rotation, an optimization algorithm based in the fulfillment of constraints and some examples of application in chemistry and environmental chemistry are given. It is shown that the solutions obtained either by alternating least squares or by the new proposed algorithm are rather similar and that they are both within the boundaries of the band of feasible solutions obtained by an algorithm previously developed to estimate them.

  1. Toward High-Resolution Monitoring of Snow and Ice in Remote Environments - Estimating the dielectric properties and SWE of snow using Duke University's L-band Snow Sensor Mote

    NASA Astrophysics Data System (ADS)

    Barros, A. P.; Kang, D.

    2008-12-01

    Measurements of snow properties at high spatial and temporal resolution are necessary to investigate and characterize the space-time scaling behavior of the hydrological and radiometric properties of surface snow and ice. Work toward the development of affordable, adaptive wireless networks of L-band snow sensor motes has been going on at Duke University for the last three years. The vision is to investigate, adapt and test existing MEMS (Micro-Electro-Mechanical Systems) and IC (Integrated Circuit) RF (radiofrequency) technology for developing low-cost (under 50 USD), low maintenance, environmentally neutral snow sensors to operate as high-spatial resolution (hundreds to thousands of sensors) wireless networks over large areas, and in remote regions (distributed from low-flying aircraft); and to develop and evaluate retrieval and snow characterization algorithms to quantify the spatial and temporal variability of water equivalent from the snow sensor measurements. The basic measurements consist of amplitude attenuation and relative phase change (snowpack/air) of electromagnetic waves in 39 channels between 1 and 1.76 GHz. Here, we present sensor and the retrieval algorithm to estimate the dielectric properties of the snowpack and snow water content from the amplitude attenuation and phase change measurements using selected channels between 1 and 1.34 GHZ. The algorithm is tested and evaluated for controlled laboratory conditions under which all state variables were measured independently. In the laboratory a synthetic snowpack was created using various types of foam with different structural characteristics and water content for which all dielectric properties were measured independently. The objective of this work is to demonstrate the skill and range of observations from the snow sensor motes to characterize the space-time heterogeneity of snow at high resolution.

  2. Geostatistics and remote sensing as predictive tools of tick distribution: a cokriging system to estimate Ixodes scapularis (Acari: Ixodidae) habitat suitability in the United States and Canada from advanced very high resolution radiometer satellite imagery.

    PubMed

    Estrada-Peña, A

    1998-11-01

    Geostatistics (cokriging) was used to model the cross-correlated information between satellite-derived vegetation and climate variables and the distribution of the tick Ixodes scapularis (Say) in the Nearctic. Output was used to map the habitat suitability for I. scapularis on a continental scale. A data base of the localities where I. scapularis was collected in the United States and Canada was developed from a total of 346 published and geocoded records. This data base was cross-correlated with satellite pictures from the advanced very high resolution radiometer sensor obtained from 1984 to 1994 on the Nearctic at 10-d intervals, with a resolution of 8 km per pixel. Eight climate and vegetation variables were tabulated from this imagery. A cokriging system was generated to exploit satellite-derived data and to estimate the distribution of I. scapularis. Results obtained using 2 vegetation (standard NDVI) and 4 temperature variables closely agreed with actual records of the tick, with a sensitivity of 0.97 and a specificity of 0.89, with 6 and 4% of false-positive and false-negative sites, respectively. Such statistical analysis can be used to guide field work toward the correct interpretation of the distribution limits of I. scapularis and can also be used to make predictions about the impact of global change on tick range.

  3. Geostatistics and remote sensing using NOAA-AVHRR satellite imagery as predictive tools in tick distribution and habitat suitability estimations for Boophilus microplus (Acari: Ixodidae) in South America. National Oceanographic and Atmosphere Administration-Advanced Very High Resolution Radiometer.

    PubMed

    Estrada-Peña, A

    1999-02-01

    Remote sensing based on NOAA (National Oceanographic and Atmosphere Administration) satellite imagery was used, together with geostatistics (cokriging) to model the correlation between the temperature and vegetation variables and the distribution of the cattle tick, Boophilus microplus (Canestrini), in the Neotropical region. The results were used to map the B. microplus habitat suitability on a continental scale. A database of B. microplus capture localities was used, which was tabulated with the AVHRR (Advanced Very High Resolution Radiometer) images from the NOAA satellite series. They were obtained at 10 days intervals between 1983 and 1994, with an 8 km resolution. A cokriging system was generated to extrapolate the results. The data for habitat suitability obtained through two vegetation and four temperature variables were strongly correlated with the known distribution of B. microplus (sensitivity 0.91; specificity 0.88) and provide a good estimation of the tick habitat suitability. This model could be used as a guide to the correct interpretation of the distribution limits of B. microplus. It can be also used to prepare eradication campaigns or to make predictions about the effects of global change on the distribution of the parasite.

  4. On 10 to 30 m-scale fracture networks in Gale Crater: Contraction of fine-grained sediments due to drying or of frozen sediments due to cooling?

    NASA Astrophysics Data System (ADS)

    Sletten, Ronald; Hallet, Bernard

    2014-05-01

    The area in Gale Crater north of the Curiosity landing site has been identified as an alluvial fan [1] and features diverse geological units [2], some with abundant contraction cracks that delineate polygons on the order of 10-30 meters across. These polygons are much larger than the < 1m flagstones seen in Yellowknife by Curiosity [3] and are more suggestive of polygonal patterned ground seen at higher latitudes on Mars [4] and Earth; however, current conditions indicate that ground ice is not stable in Gale Crater [4]. Nevertheless, past conditions, e.g. obliquity changes, may have allowed permafrost to develop and ground ice to form. The domains between the larger polygons are several meters wide, which is consistent with cyclic ratcheting of ice-cemented permafrost (thermal contraction with fractures opening, debris infilling the fractures, and the fractures not closing fully when the ground warms and expands). On the other hand, the large-scale crack networks often seem to be associated with certain lithologic units, including the thinly-bedded, lightly-colored mudstones exposed at Yellowknife. This suggests that the contraction cracks defining these 10 to 30-m polygons, as well as those defining the < 1m flagstones, formed in moist fine-grained sediments that contracted upon desiccation. If the fractures were due to contraction of ice-cemented permafrost, they would be insensitive to the type of sediments they formed in because the mechanical properties would be dominated by ice. The interpretation of the larger-scale crack network is limited to satellite images since Curiosity did not visit this area, and to evidence about surface materials elsewhere in the vicinity of the rover. This evidence points to the former presence of flowing water in Gale Crater and existence of shallow lakes of relatively low salinity and near-neutral pH at Yellowknife [5]. The large amount of contraction in Yellowknife deposits is consistent with a desiccation origin in these

  5. Characterizing uncertainties of the national-scale forest gross aboveground biomass (AGB) loss estimate: a case study of the Democratic Republic of the Congo

    NASA Astrophysics Data System (ADS)

    Tyukavina, A.; Stehman, S.; Potapov, P.; Turubanova, S.; Baccini, A.; Goetz, S. J.; Laporte, N. T.; Houghton, R. A.; Hansen, M.

    2013-12-01

    Modern remote sensing techniques enable the mapping and monitoring of aboveground biomass (AGB) carbon stocks without relying on extensive in situ measurements. The Democratic Republic of the Congo (DRC) is among the countries where a national forest inventory (NFI) has yet to be established due to a lack of infrastructure and political instability. We demonstrate a method for producing national-scale gross AGB loss estimates and quantifying uncertainty of the estimates using remotely sensed-derived forest cover loss and biomass carbon density data. Forest cover type and loss were characterized using published Landsat-based data sets and related to LIDAR-derived biomass data from the Geoscience Laser Altimeter System (GLAS). We produced two gross AGB loss estimates for the DRC for the last decade (2000-2010): a conservative estimate accounting for classification errors in the 60-m resolution FACET forest cover change product, and a maximal estimate that also took into consideration omitted change at the 30m spatial resolution. Omitted disturbances were largely related to smallholder agriculture, the detection of which is scale-dependent. The use of LIDAR data as a substitute for NFI data to estimate AGB loss based on Landsat-derived activity data was demonstrated. Comparisons of our forest cover loss and AGB estimates with published studies raise the issue of scale in forest cover change mapping and its impact on carbon stock change estimation using remotely sensed data.

  6. Role of the disease in the psychological impact of pre-symptomatic testing for SCA2 and FAP ATTRV30M: Experience with the disease, kinship and gender of the transmitting parent.

    PubMed

    Paneque, Milena; Lemos, Carolina; Sousa, Alda; Velázquez, Luis; Fleming, Manuela; Sequeiros, Jorge

    2009-10-01

    To identify possible factors affecting the psychological impact of pre-symptomatic testing for spinocerebellar ataxia type 2 (SCA2) and familial amyloid polyneuropathy (FAP ATTRV30M), we studied (1) the effect of previous experience with the disease in the family, (2) kinship with the closest affected relative and (3) gender of affected parent, when adapting to test results; as well as (4) differences in the course of psychological wellbeing in 63 subjects ( 28 at-risk for FAP ATTRV30M, and 35 at risk for SCA2), who pursued predictive testing for these diseases, in Cuba and in Portugal. Our research shows that individuals with little or no experience with the disease in their family exhibited more anxiety; at-risk subjects for SCA2 or FAP ATTRV30M who had a first degree relative with the disease showed lower levels of anxiety and depression during pre-symptomatic testing. Also those with an affected mother had lower levels of depression, either immediately, or one year after receipt of test results. Adaptation to pre-symptomatic testing results differed for subjects at-risk for the two different conditions. Unlike the FAP ATTRV30M families, carriers for SCA2 reported pathological levels of depression immediately after-testing (3 weeks), although those levels had returned to normal levels at 6 months. Subjects at-risk for FAP ATTRV30M tended to have less anxiety than those tested for SCA2, at the one-year follow-up. Overall, depression levels improved over time, while anxiety remained more constant. A longer awareness of the disease in the family, closer kinship, and a transmitting mother all lessened the impact of pre-symptomatic testing, as expressed by the post-test levels of anxiety and depression.

  7. Conflict resolution.

    PubMed

    Levin, Roger

    2006-03-01

    The sooner conflict is identified and confronted, the more quickly it can be resolved (and the sooner, the better). When this is accomplished calmly and objectively, many areas of conflict will be eliminated. Addressing conflict as it arises also sends a clear message to the team that the practice seeks resolution, not punishment or negative consequences. In addition, the dentist and the office manager need to lead by example by avoiding gossip and encouraging open communication. The goal is to go from a parent-child relationship with the dental team to an adult-adult relationship using this series of managerial conflict resolution steps.

  8. Fuzzy logic structure analysis of trabecular bone of the calcaneus to estimate proximal femur fracture load and discriminate subjects with and without vertebral fractures using high-resolution magnetic resonance imaging at 1.5 T and 3 T.

    PubMed

    Patel, Priyesh V; Eckstein, Felix; Carballido-Gamio, Julio; Phan, Catherine; Matsuura, Maiko; Lochmüller, Eva-Maria; Majumdar, Sharmila; Link, Thomas M

    2007-10-01

    Newly developed fuzzy logic-derived structural parameters were used to characterize trabecular bone architecture in high-resolution magnetic resonance imaging (HR-MRI) of human cadaver calcaneus specimens. These parameters were compared to standard histomorphological structural measures and analyzed concerning performance in discriminating vertebral fracture status and estimating proximal femur fracture load. Sets of 60 sagittal 1.5 T and 3.0 T HR-MRI images of the calcaneus were obtained in 39 cadavers using a fast gradient recalled echo sequence. Structural parameters equivalent to bone histomorphometry and fuzzy logic-derived parameters were calculated using two chosen regions of interest. Calcaneal, spine, and hip bone mineral density (BMD) measurements were also obtained. Fracture status of the thoracic and lumbar spine was assessed on lateral radiographs. Finally, mechanical strength testing of the proximal femur was performed. Diagnostic performance in discriminating vertebral fracture status and estimating femoral fracture load was calculated using regression analyses, two-tailed t-tests of significance, and receiver operating characteristic (ROC) analyses. Significant correlations were obtained at both field strengths between all structural and fuzzy logic parameters (r up to 0.92). Correlations between histomorphological or fuzzy logic parameters and calcaneal BMD were mostly significant (r up to 0.78). ROC analyses demonstrated that standard structural parameters were able to differentiate persons with and without vertebral fractures (area under the curve [A(Z)] up to 0.73). However, none of the parameters obtained in the 1.5-T images and none of the fuzzy logic parameters discriminated persons with and without vertebral fractures. Significant correlations were found between fuzzy or structural parameters and femoral fracture load. Using multiple regression analysis, none of the structural or fuzzy parameters were found to add discriminative value to BMD

  9. Assessing Changes in Impervious Area Using Land Use Maps of Different Resolution in the Croton NY City Water Supply Watershed

    NASA Astrophysics Data System (ADS)

    Somerlot, C.; Duncan, J.; Endreny, T.

    2001-05-01

    With the advance of remote sensing, options arise for the hydrologic modeler to access both public domain and privately contracted watershed land cover maps. Land use classification processes using aerial photographs are highly variable depending on tools and training, but distinction between impervious and pervious land cover is relatively simple. Hydrologic models will estimate different runoff timing, volume, and water quality depending on the percent imperviousness of the watershed. This research will examine how percent imperviousness varies with changes in both radiometric and spatial land cover map resolution. WinHSPF was run with four distinct land cover maps derived from remote imagery: MRLC (30 m), LULC (1 km), contracted aerial photos (1 m), and processed digital (1 M) ortho quarter quads. Comparisons were made between map percent impervious cover and runoff timing and volume. A modified export coefficient model that tracks pollutant discharge through down gradient filters examined how estimated nutrient loading changed with differences in these land cover map products. Methods are suggested for updating estimates of percent impervious cover in coarser resolution maps using field data or other means.

  10. Satellite Estimates of Crop Area and Maize Yield in Zambia's Agricultural Districts

    NASA Astrophysics Data System (ADS)

    Azzari, G.; Lobell, D. B.

    2015-12-01

    Predicting crop yield and area from satellite is a valuable tool to monitor different aspects of productivity dynamics and food security. In Sub-Saharan Africa, where the agricultural landscape is complex and dominated by smallholder systems, such dynamics need to be investigated at the field scale. We leveraged the large data pool and computational power of Google Earth Engine to 1) generate 30 m resolution cover maps of selected provinces of Zambia, 2) estimate crop area, and 3) produce yearly maize yield maps using the recently developed SCYM (Scalable satellite-based Crop Yield Mapper) algorithm. We will present our results and their validation against a ground survey dataset collected yearly by the Zambia Ministry of Agriculture from about 12,500 households.

  11. NCAI Resolutions

    ERIC Educational Resources Information Center

    American Indian Journal of the Institute for the Development of Indian Law, 1977

    1977-01-01

    Five Major Policy Resolutions were adopted, without objection, at the 33rd Annual Convention of the National Congress of American Indians (NCAI) held in Salt Lake City, Utah, in October 1976. The issues involved were: Treaties and Trust Responsibilities, Tribal Government, Jurisdiction, Federal Administration and Structure of Indian Affairs, and…

  12. Estimation of yield and water requirements of maize crops combining high spatial and temporal resolution images with a simple crop model, in the perspective of the Sentinel-2 mission

    NASA Astrophysics Data System (ADS)

    Battude, Marjorie; Bitar, Ahmad Al; Brut, Aurore; Cros, Jérôme; Dejoux, Jean-François; Huc, Mireille; Marais Sicre, Claire; Tallec, Tiphaine; Demarez, Valérie

    2016-04-01

    Water resources are under increasing pressure as a result of global change and of a raising competition among the different users (agriculture, industry, urban). It is therefore important to develop tools able to estimate accurately crop water requirements in order to optimize irrigation while maintaining acceptable production. In this context, remote sensing is a valuable tool to monitor vegetation development and water demand. This work aims at developing a robust and generic methodology mainly based on high resolution remote sensing data to provide accurate estimates of maize yield and water needs at the watershed scale. Evapotranspiration (ETR) and dry aboveground biomass (DAM) of maize crops were modeled using time series of GAI images used to drive a simple agro-meteorological crop model (SAFYE, Duchemin et al., 2005). This model is based on a leaf partitioning function (Maas, 1993) for the simulation of crop biomass and on the FAO-56 methodology for the ETR simulation. The model also contains a module to simulate irrigation. This study takes advantage of the SPOT4 and SPOT5 Take5 experiments initiated by CNES (http://www.cesbio.ups-tlse.fr/multitemp/). They provide optical images over the watershed from February to May 2013 and from April to August 2015 respectively, with a temporal and spatial resolution similar to future images from the Sentinel-2 and VENμS missions. This dataset was completed with LandSat8 and Deimos1 images in order to cover the whole growing season while reducing the gaps in remote sensing time series. Radiometric, geometric and atmospheric corrections were achieved by the THEIA land data center, and the KALIDEOS processing chain. The temporal dynamics of the green area index (GAI) plays a key role in soil-plant-atmosphere interactions and in biomass accumulation process. Consistent seasonal dynamics of the remotely sensed GAI was estimated by applying a radiative transfer model based on artificial neural networks (BVNET, Baret

  13. A reliable compound-specific nitrogen isotope analysis of amino acids by GC-C-IRMS following derivatisation into N-pivaloyl-iso-propyl (NPIP)esters for high-resolution food webs estimation.

    PubMed

    Zhang, Zhongyi; Tian, Jing; Xiao, Hongwei; Zheng, Nengjian; Gao, Xiaofei; Zhu, Renguo; Xiao, Huayun

    2016-10-15

    The signatures of natural stable nitrogen isotopic composition (δ(15)N) of individual amino acid (AA) have been confirmed to be a potentially effective tool for elucidating nitrogen cycling and trophic position of various organisms in food webs. In the present study, a two-stage derivatisation approach of esterification followed by acylation was evaluated. The biological samples underwent acid hydrolysis and the released individual AA was derivatived into corresponding N-pivaloyl-isopropyl (NPIP) esters for nitrogen isotopic analysis in gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). Usually, 13 individual AA derivatives were separated with fine baseline resolution based on a nonpolar gas chromatography column (DB-5ms). The minimum sample amount required under the presented conditions is larger than 20ngN on column in order to accurately determine the δ(15)N values. The δ(15)N values determined by GC-C-IRMS with a precision of better than 1‰, were within 1‰ after empirical correction compared to the corresponding measured by element analysis (EA)-IRMS. Bland-Altman plot showed highly consistency of the δ(15)N values determined by the two measurement techniques. Cation-exchange chromatography was applied to remove interfering fraction from the extracts of plant and animal samples and without nitrogen isotope fractionation during the treatment procedure. Moreover, this approach was carried out to estimate the trophic level of various natural organisms in a natural lake environment. Results highly proved that the trophic level estimated via the presented AA method well reflected the actual food web structure in natural environments.

  14. Intra- and Inter-Seasonal Supra-glacial Water Variability over the West Greenland Ice Sheet as Estimated from Combining High Resolution Satellite Optical Data and a Digital Elevation Model

    NASA Astrophysics Data System (ADS)

    Brown, M. G.; Tedesco, M.; Smith, L. C.; Rennermalm, A. K.; Yang, K.

    2015-12-01

    The supra-glacial hydrology of the Greenland Ice Sheet (GrIS) plays a crucial role on the surface energy and mass balance budgets of the ice sheet as a whole. The surface hydrology network variability of small streams in the ablation zone of Greenland is poorly understood both spatially and temporally. Using satellites that can spatially resolve the presence and associated properties of small streams, the scientific community is now able to be provided with accurate spatial and temporal analysis of surface hydrology on the ice sheet (that could not have been resolved with other sensors such as those on board MODIS or LANDSAT). In this study we report mapped supra-glacial water networks over a region of the West GrIS (approximately 164 km2) derived from high resolution multispectral satellite imagery from the Quickbird and WorldView - 2 satellites in tandem with a 2 meter stereographic SETSM DEM (digital elevation model). The branching complexity of the identified surface streams is computed from the available DEM as well as the intra- and inter seasonal changes observed in the hydrological system. The stream networks created during the melt season (at several different stages of melting) are compared and discussed as well as the networks mapped between consecutive years for proximate dates. Also, depth and volume estimations for the surface water features identified were extracted via band math algorithms, threshold classifications, and morphological operations. Our results indicate that the higher stream orders have the largest amount of stored surface water per km but the lower stream orders, specifically 1st order with widths of ~ 2 meters, hold more stored surface water overall. We also employ and compare runoff data from the numerical model MAR (Modèle Atmosphérique Régional) to the estimations found using imagery and the DEM.

  15. National-scale estimation of gross forest aboveground carbon loss: a case study of the Democratic Republic of the Congo

    NASA Astrophysics Data System (ADS)

    Tyukavina, A.; Stehman, S. V.; Potapov, P. V.; Turubanova, S. A.; Baccini, A.; Goetz, S. J.; Laporte, N. T.; Houghton, R. A.; Hansen, M. C.

    2013-12-01

    Recent advances in remote sensing enable the mapping and monitoring of carbon stocks without relying on extensive in situ measurements. The Democratic Republic of the Congo (DRC) is among the countries where national forest inventories (NFI) are either non-existent or out of date. Here we demonstrate a method for estimating national-scale gross forest aboveground carbon (AGC) loss and associated uncertainties using remotely sensed-derived forest cover loss and biomass carbon density data. Lidar data were used as a surrogate for NFI plot measurements to estimate carbon stocks and AGC loss based on forest type and activity data derived using time-series multispectral imagery. Specifically, DRC forest type and loss from the FACET (Forêts d’Afrique Centrale Evaluées par Télédétection) product, created using Landsat data, were related to carbon data derived from the Geoscience Laser Altimeter System (GLAS). Validation data for FACET forest area loss were created at a 30-m spatial resolution and compared to the 60-m spatial resolution FACET map. We produced two gross AGC loss estimates for the DRC for the last decade (2000-2010): a map-scale estimate (53.3 ± 9.8 Tg C yr-1) accounting for whole-pixel classification errors in the 60-m resolution FACET forest cover change product, and a sub-grid estimate (72.1 ± 12.7 Tg C yr-1) that took into account 60-m cells that experienced partial forest loss. Our sub-grid forest cover and AGC loss estimates, which included smaller-scale forest disturbances, exceed published assessments. Results raise the issue of scale in forest cover change mapping and validation, and subsequent impacts on remotely sensed carbon stock change estimation, particularly for smallholder dominated systems such as the DRC.

  16. High spectral resolution reflectance spectroscopy of minerals

    USGS Publications Warehouse

    Clark, R.N.; King, T.V.V.; Klejwa, M.; Swayze, G.A.; Vergo, N.

    1990-01-01

    The reflectance spectra of minerals are studied as a function of spectral resolution in the range from 0.2 to 3.0 ??m. Selected absorption bands were studied at resolving powers (??/????) as high as 2240. At resolving powers of approximately 1000, many OH-bearing minerals show diagnostic sharp absorptions at the resolution limit. At low resolution, some minerals may not be distinguishable, but as the resolution is increased, most can be easily identified. As the resolution is increased, many minerals show fine structure, particularly in the OH-stretching overtone region near 1.4 ??m. The fine structure can enhance the ability to discriminate between minerals, and in some cases the fine structure can be used to determine elemental composition. The study shows that high-resolution reflectance spectroscopy of minerals may prove to be a very important tool in the laboratory, in the field using field-portable spectrometers, from aircraft, and from satellites looking at Earth or other planetary surfaces. -from Authors

  17. Resolution Enhancement of MODIS-Derived Water Indices for Studying Persistent Flooding

    NASA Technical Reports Server (NTRS)

    Underwood, L. W.; Kalcic, Maria; Fletcher, Rose

    2012-01-01

    Monitoring coastal marshes for persistent flooding and salinity stress is a high priority issue in Louisiana. Remote sensing can identify environmental variables that can be indicators of marsh habitat conditions, and offer timely and relatively accurate information for aiding wetland vegetation management. Monitoring activity accuracy is often limited by mixed pixels which occur when areas represented by the pixel encompasses more than one cover type. Mixtures of marsh grasses and open water in 250m Moderate Resolution Imaging Spectroradiometer (MODIS) data can impede flood area estimation. Flood mapping of such mixtures requires finer spatial resolution data to better represent the cover type composition within 250m MODIS pixel. Fusion of MODIS and Landsat can improve both spectral and temporal resolution of time series products to resolve rapid changes from forcing mechanisms like hurricane winds and storm surge. For this study, using a method for estimating sub-pixel values from a MODIS time series of a Normalized Difference Water Index (NDWI), using temporal weighting, was implemented to map persistent flooding in Louisiana coastal marshes. Ordinarily NDWI computed from daily 250m MODIS pixels represents a mixture of fragmented marshes and water. Here, sub-pixel NDWI values were derived for MODIS data using Landsat 30-m data. Each MODIS pixel was disaggregated into a mixture of the eight cover types according to the classified image pixels falling inside the MODIS pixel. The Landsat pixel means for each cover type inside a MODIS pixel were computed for the Landsat data preceding the MODIS image in time and for the Landsat data succeeding the MODIS image. The Landsat data were then weighted exponentially according to closeness in date to the MODIS data. The reconstructed MODIS data were produced by summing the product of fractional cover type with estimated NDWI values within each cover type. A new daily time series was produced using both the reconstructed 250

  18. Compromised trabecular microarchitecture and lower finite element estimates of radius and tibia bone strength in adults with turner syndrome: a cross-sectional study using high-resolution-pQCT.

    PubMed

    Hansen, Stinus; Brixen, Kim; Gravholt, Claus H

    2012-08-01

    Although bone mass appear ample for bone size in Turner syndrome (TS), epidemiological studies have reported an increased risk of fracture in TS. We used high-resolution peripheral quantitative computed tomography (HR-pQCT) to measure standard morphological parameters of bone geometry and microarchitecture, as well as estimated bone strength by finite element analysis (FEA) to assess bone characteristics beyond bone mineral density (BMD) that possibly contribute to the increased risk of fracture. Thirty-two TS patients (median age 35, range 20-61 years) and 32 healthy control subjects (median age 36, range 19-58 years) matched with the TS participants with respect to age and body-mass index were studied. A full region of interest (ROI) image analysis and a height-matched ROI analysis adjusting for differences in body height between groups were performed. Mean bone cross-sectional area was lower in TS patients in radius (-15%) and tibia (-13%) (both p < 0.01) whereas cortical thickness was higher in TS patients in radius (18%, p < 0.01) but not in tibia compared to controls. Cortical porosity was lower in TS patients at both sites (-32% in radius, -36% in tibia, both p < 0.0001). Trabecular integrity was compromised in TS patients with lower bone volume per tissue volume (BV/TV) (-27% in radius, -22% in tibia, both p < 0.0001), trabecular number (-27% in radius, -12% in tibia, both p < 0.05), and higher trabecular spacing (54% in radius, 23% in tibia, both p < 0.01). In the height-matched ROI analysis, differences remained significant apart from total area at both sites, cortical thickness in radius, and trabecular number in tibia. FEA estimated failure load was lower in TS patients in both radius (-11%) and tibia (-16%) (both p < 0.01) and remained significantly lower in the height-matched ROI analysis. Conclusively, TS patients had compromised trabecular microarchitecture and lower bone strength at both skeletal sites, which may partly

  19. Resolution in Photovoltaic Potential Computation

    NASA Astrophysics Data System (ADS)

    Alam, N.; Coors, V.; Zlatanova, S.; Oosterom, P. J. M.

    2016-09-01

    In this paper, an analysis of the effect of the various types of resolution involved in photovoltaic potential computation is presented. To calculate solar energy incident on a surface, shadow from surrounding buildings has been considered. The incident energy on a surface has been calculated taking the orientation, tilt and position into consideration. Different sky visibility map has been created for direct and diffuse radiation and only the effect of resolution of the factors has been explored here. The following four resolutions are considered: 1. temporal resolution (1, 10, 60 minutes time interval for calculating visibility of sun), 2. object surface resolution (0.01, 0.1, 0.375, 0.75, 1.25, 2.5 and 5 m2 as maximum triangle size of a surface to be considered), 3. blocking obstacle resolution (number of triangles from LoD1, LoD2, or LoD3 CityGML building models), and 4. sky resolution (ranging from 150 to 600 sky-patches used to divide the sky-dome). Higher resolutions result in general in more precise estimation of the photovoltaic potential, but also the computation time is increasing, especially as realizes that this computation has to be done for every building with its object surface (both roofs and façades). This paper is the first in depth analysis ever of the effect of resolution and will help to configure the proper settings for effective photovoltaic potential computations.

  20. Direct-Push Methods for High-Resolution Characterization of Hydraulic Conductivity (Invited)

    NASA Astrophysics Data System (ADS)

    Butler, J. J.; Dietrich, P.; Knobbe, S.; Bohling, G.; Liu, G.; Reboulet, E. C.

    2009-12-01

    Spatial variations in hydraulic conductivity (K) play a critical role in subsurface transport. A major research challenge has been to develop field methods that allow K information to be obtained at the resolution needed to quantify solute movement in heterogeneous formations, as current state-of-the-practice methods have proven to be of limited effectiveness for this purpose. Direct-push methods have shown much promise for characterizing K in shallow (< 30 m) unconsolidated formations. Over the past decade, methods have progressed from empirical relationships based on parameters from cone penetrometer or electrical conductivity logs to small-diameter pipe variants of the slug test to the new generation of methods that can provide reliable K estimates at a resolution and speed that has not previously been possible. Over the last six years, we have focused on developing and field testing two direct-push tools for high-resolution characterization of K: the direct-push permeameter (DPP) and the direct-push injection logger (DPIL). The DPP is a small-diameter tool with a short cylindrical screen and two pressure transducers set into a direct-push rod. A series of injection tests are performed at a given depth and K is estimated from the test responses. The resulting estimate is a weighted average primarily over the interval between the screen and the farthest transducer. Material outside of that interval has little influence, resulting in significant uncertainty about conditions between test depths. The time required for a test sequence (10-15 minutes in moderate to high-K intervals), coupled with the volumetric averaging of the tool, currently limits DPP resolution to ≈ 0.4 m in most cases. The DPIL consists of a single screened port on a direct-push rod. Water is injected through the screen while the pressure response is monitored behind the screen or at the surface. The injection logging process can be conducted continuously at 0.015-m resolution as the tool is

  1. Recent wetland land loss due to hurricanes: improved estimates based upon multiple source images

    USGS Publications Warehouse

    Kranenburg, Christine J.; Palaseanu-Lovejoy, Monica; Barras, John A.; Brock, John C.; Wang, Ping; Rosati, Julie D.; Roberts, Tiffany M.

    2011-01-01

    The objective of this study was to provide a moderate resolution 30-m fractional water map of the Chenier Plain for 2003, 2006 and 2009 by using information contained in high-resolution satellite imagery of a subset of the study area. Indices and transforms pertaining to vegetation and water were created using the high-resolution imagery, and a threshold was applied to obtain a categorical land/water map. The high-resolution data was used to train a decision-tree classifier to estimate percent water in a lower resolution (Landsat) image. Two new water indices based on the tasseled cap transformation were proposed for IKONOS imagery in wetland environments and more than 700 input parameter combinations were considered for each Landsat image classified. Final selection and thresholding of the resulting percent water maps involved over 5,000 unambiguous classified random points using corresponding 1-m resolution aerial photographs, and a statistical optimization procedure to determine the threshold at which the maximum Kappa coefficient occurs. Each selected dataset has a Kappa coefficient, percent correctly classified (PCC) water, land and total greater than 90%. An accuracy assessment using 1,000 independent random points was performed. Using the validation points, the PCC values decreased to around 90%. The time series change analysis indicated that due to Hurricane Rita, the study area lost 6.5% of marsh area, and transient changes were less than 3% for either land or water. Hurricane Ike resulted in an additional 8% land loss, although not enough time has passed to discriminate between persistent and transient changes.

  2. The Effects of a 6-Week Strength Training on Critical Velocity, Anaerobic Running Distance, 30-M Sprint and Yo-Yo Intermittent Running Test Performances in Male Soccer Players

    PubMed Central

    Karsten, Bettina; Larumbe-Zabala, Eneko; Kandemir, Gokhan; Hazir, Tahir; Klose, Andreas; Naclerio, Fernando

    2016-01-01

    The objectives of this study were to examine the effects of a moderate intensity strength training on changes in critical velocity (CV), anaerobic running distance (D'), sprint performance and Yo-Yo intermittent running test (Yo-Yo IR1) performances. Methods: two recreational soccer teams were divided in a soccer training only group (SO; n = 13) and a strength and soccer training group (ST; n = 13). Both groups were tested for values of CV, D', Yo-Yo IR1 distance and 30-m sprint time on two separate occasions (pre and post intervention). The ST group performed a concurrent 6-week upper and lower body strength and soccer training, whilst the SO group performed a soccer only training. Results: after the re-test of all variables, the ST demonstrated significant improvements for both, YoYo IR1 distance (p = 0.002) and CV values (p<0.001) with no significant changes in the SO group. 30-m sprint performance were slightly improved in the ST group with significantly decreased performance times identified in the SO group (p<0.001). Values for D' were slightly reduced in both groups (ST -44.5 m, 95% CI = -90.6 to 1.6; SO -42.6 m, 95% CI = -88.7 to 3.5). Conclusions: combining a 6-week moderate strength training with soccer training significantly improves CV, Yo-Yo IR1 whilst moderately improving 30-m sprint performances in non-previously resistance trained male soccer players. Critical Velocity can be recommended to coaches as an additional valid testing tool in soccer. PMID:27015418

  3. Satellite-based monitoring of particulate matter pollution at very high resolution: the HOTBAR method

    NASA Astrophysics Data System (ADS)

    Wilson, Robin; Milton, Edward; Nield, Joanna

    2016-04-01

    Particulate matter air pollution is a major health risk, and is responsible for millions of premature deaths each year. Concentrations tend to be highest in urban areas - particularly in the mega-cities of rapidly industrialising countries, where there are limited ground monitoring networks. Satellite-based monitoring has been used for many years to assess regional-scale trends in air quality, but currently available satellite products produce data at 1-10km resolution: too coarse to discern the small-scale patterns of sources and sinks seen in urban areas. Higher-resolution satellite products are required to provide accurate assessments of particulate matter concentrations in these areas, and to allow analysis of localised air quality effects on health. The Haze Optimized Transform-based Aerosol Retrieval (HOTBAR) method is a novel method which provides estimates of PM2.5 concentrations from high-resolution (approximately 30m) satellite imagery. This method is designed to work over a wide range of land covers and performs well over the complex land-cover mosaic found in urban areas. It requires only standard visible and near-infrared data, making it applicable to a range of data from sensors such as Landsat, SPOT and Sentinel-2. The method is based upon an extension of the Haze Optimized Transform (HOT), which was originally designed for assessing areas of thick haze in satellite imagery. This was done by calculating a 'haziness' value for each pixel in an image as the distance from a 'Clear Line' in feature space, defined by the high correlation between visible bands. Here, we adapt the HOT method and use it to estimate Aerosol Optical Thickness (a measure of the column-integrated haziness of the atmosphere) instead, from which PM2.5 concentrations can then be estimated. Significant extensions to the original HOT method include Monte Carlo estimation of the 'Clear Line', object-based correction for land cover, and estimation of AOT from the haziness values

  4. Estimation of Droplet Size and Liquid Water Content Using Radar and Lidar: Marine Cumulus Clouds

    NASA Astrophysics Data System (ADS)

    Vivekanandan, J. Vivek; Jensen, Jorgen; Ellis, Scott; Morley, Bruce; Tsai, Peisang; Spuler, Scott; Ghate, Virendra; Schwartz, Christian

    2016-04-01

    During the Cloud Systems Evolution in the Trades (CSET) field campaign airborne measurements from the High-Performance Instrumented Airborne Platform for Environmental Research (HIAPER) Cloud Radar (HCR) and the High Spectral Resolution Lidar (HSRL) were made in the North Pacific. In addition, in situ observations of cloud and aerosols size distributions and radiation were also collected. The HCR operated at a frequency of 94 GHz (3 mm wavelength) and collected observations at high temporal (0.5 sec) and range (30 m) resolution. The capability of HCR is enhanced by the coordination with the HSRL that made high temporal and range resolution observations of calibrated backscatter and extinction. The lidar, designed and built by the University of Wisconsin. The radar and lidar are designed to fly on the NCAR Gulfstream V HIAPER aircraft. The remote and in situ measurements collected during CSET offer opportunities for evaluating the engineering performance of the instruments and developing cloud microphysical scientific products. The coincident HCR and HSRL measurements are analyzed for assess their utility to characterize cloud boundaries, estimate liquid water content (LWC) and mean particle size. Retrievals of LWC and mean particle sizes from remote radar and lidar measurements will be compared with those from the in situ instruments.

  5. Preliminary verification of instantaneous air temperature estimation for clear sky conditions based on SEBAL

    NASA Astrophysics Data System (ADS)

    Zhu, Shanyou; Zhou, Chuxuan; Zhang, Guixin; Zhang, Hailong; Hua, Junwei

    2017-02-01

    Spatially distributed near surface air temperature at the height of 2 m is an important input parameter for the land surface models. It is of great significance in both theoretical research and practical applications to retrieve instantaneous air temperature data from remote sensing observations. An approach based on Surface Energy Balance Algorithm for Land (SEBAL) to retrieve air temperature under clear sky conditions is presented. Taking the meteorological measurement data at one station as the reference and remotely sensed data as the model input, the research estimates the air temperature by using an iterative computation. The method was applied to the area of Jiangsu province for nine scenes by using MODIS data products, as well as part of Fujian province, China based on four scenes of Landsat 8 imagery. Comparing the air temperature estimated from the proposed method with that of the meteorological station measurement, results show that the root mean square error is 1.7 and 2.6 °C at 1000 and 30 m spatial resolution respectively. Sensitivity analysis of influencing factors reveals that land surface temperature is the most sensitive to the estimation precision. Research results indicate that the method has great potentiality to be used to estimate instantaneous air temperature distribution under clear sky conditions.

  6. Assessing resolution in super-resolution imaging.

    PubMed

    Demmerle, Justin; Wegel, Eva; Schermelleh, Lothar; Dobbie, Ian M

    2015-10-15

    Resolution is a central concept in all imaging fields, and particularly in optical microscopy, but it can be easily misinterpreted. The mathematical definition of optical resolution was codified by Abbe, and practically defined by the Rayleigh Criterion in the late 19th century. The limit of conventional resolution was also achieved in this period, and it was thought that fundamental constraints of physics prevented further increases in resolution. With the recent development of a range of super-resolution techniques, it is necessary to revisit the concept of optical resolution. Fundamental differences in super-resolution modalities mean that resolution is not a directly transferrable metric between techniques. This article considers the issues in resolution raised by these new technologies, and presents approaches for comparing resolution between different super-resolution methods.

  7. High resolution measurements supported by electronic structure calculations of two naphthalene derivatives: [1,5]- and [1,6]-naphthyridine—Estimation of the zero point inertial defect for planar polycyclic aromatic compounds

    SciTech Connect

    Gruet, S. E-mail: manuel.goubet@univ-lille1.fr; Pirali, O.; Goubet, M. E-mail: manuel.goubet@univ-lille1.fr

    2014-06-21

    Polycyclic aromatic hydrocarbons (PAHs) molecules are suspected to be present in the interstellar medium and to participate to the broad and unresolved emissions features, the so-called unidentified infrared bands. In the laboratory, very few studies report the rotationally resolved structure of such important class of molecules. In the present work, both experimental and theoretical approaches provide the first accurate determination of the rotational energy levels of two diazanaphthalene: [1,5]- and [1,6]-naphthyridine. [1,6]-naphthyridine has been studied at high resolution, in the microwave (MW) region using a Fourier transform microwave spectrometer and in the far-infrared (FIR) region using synchrotron-based Fourier transform spectroscopy. The very accurate set of ground state (GS) constants deduced from the analysis of the MW spectrum allowed the analysis of the most intense modes in the FIR (ν{sub 38}-GS centered at about 483 cm{sup −1} and ν{sub 34}-GS centered at about 842 cm{sup −1}). In contrast with [1,6]-naphthyridine, pure rotation spectroscopy of [1,5]-naphthyridine cannot be performed for symmetry reasons so the combined study of the two intense FIR modes (ν{sub 22}-GS centered at about 166 cm{sup −1} and ν{sub 18}-GS centered at about 818 cm{sup −1}) provided the GS and the excited states constants. Although the analysis of the very dense rotational patterns for such large molecules remains very challenging, relatively accurate anharmonic density functional theory calculations appeared as a highly relevant supporting tool to the analysis for both molecules. In addition, the good agreement between the experimental and calculated infrared spectrum shows that the present theoretical approach should provide useful data for the astrophysical models. Moreover, inertial defects calculated in the GS (Δ{sub GS}) of both molecules exhibit slightly negative values as previously observed for planar species of this molecular family. We adjusted

  8. Estimating the spatial distribution of evapotranspiration using the water balance model WAVE and fine spatial resolution airborne remote sensing images from the DAIS-sensor: Experimental set-up

    NASA Astrophysics Data System (ADS)

    Verstraeten, W. W.; Veroustraete, F.; Feyen, J.

    2003-04-01

    Actual evapotranspiration (ET) of agricultural land and forestland surfaces play an important role in the redistribution of water on the Earth's surface. Any change in evapotranspiration, either through change in vegetation or climate change, directly effects the available water resources. For quantifying these effects physical models need to be constructed. Most hydrological models have to deal with a lack of good spatial resolution, despite their good temporal information. Remote sensing techniques on the contrary determine the spatial pattern of landscape features and hence are very useful on large scales. The main objective of this research is the combination of the spatial pattern of remote sensing (using visible and thermal infrared spectrum) with the temporal pattern of the water balance model WAVE (Vanclooster et al., 1994 and 1996). To realise this, the following objectives are formulated: (i) relate soil and vegetation surface temperatures to actual evapotranspiration of forest and crops simulated with the water balance model WAVE using remote sensing derived parameters. Three methods will be used and mutually compared. Both airborne and satellite imagery will be implemented; (1) compare the spatial pattern of evapotranspiration, as a result of the three methods, with the energy balance model SEBAL (Bastiaanssen et al., 1998) and finally; (2) subject the up-scaled WAVE and SEBAL models to an uncertainty analysis using the GLUE-approach (Generalised Likelihood Uncertainty Estimate) (Beven en Binley, 1992). To study the behaviour of the model beyond the field-scale (micro-scale), a meso-scale study was conducted at the test-site of DURAS (50°50'38"N, 5°08'50"W, Sint-Truiden). Airborne imagery from the DAIS/ROSIS sensor are available. For the determination of the spatial pattern of actual evapotranspiration the next two methods are considered: (1) relations between surface temperature, surface albedo and vegetation indices are linked with field

  9. High resolution measurements supported by electronic structure calculations of two naphthalene derivatives: [1,5]- and [1,6]-naphthyridine--estimation of the zero point inertial defect for planar polycyclic aromatic compounds.

    PubMed

    Gruet, S; Goubet, M; Pirali, O

    2014-06-21

    Polycyclic aromatic hydrocarbons (PAHs) molecules are suspected to be present in the interstellar medium and to participate to the broad and unresolved emissions features, the so-called unidentified infrared bands. In the laboratory, very few studies report the rotationally resolved structure of such important class of molecules. In the present work, both experimental and theoretical approaches provide the first accurate determination of the rotational energy levels of two diazanaphthalene: [1,5]- and [1,6]-naphthyridine. [1,6]-naphthyridine has been studied at high resolution, in the microwave (MW) region using a Fourier transform microwave spectrometer and in the far-infrared (FIR) region using synchrotron-based Fourier transform spectroscopy. The very accurate set of ground state (GS) constants deduced from the analysis of the MW spectrum allowed the analysis of the most intense modes in the FIR (ν38-GS centered at about 483 cm(-1) and ν34-GS centered at about 842 cm(-1)). In contrast with [1,6]-naphthyridine, pure rotation spectroscopy of [1,5]-naphthyridine cannot be performed for symmetry reasons so the combined study of the two intense FIR modes (ν22-GS centered at about 166 cm(-1) and ν18-GS centered at about 818 cm(-1)) provided the GS and the excited states constants. Although the analysis of the very dense rotational patterns for such large molecules remains very challenging, relatively accurate anharmonic density functional theory calculations appeared as a highly relevant supporting tool to the analysis for both molecules. In addition, the good agreement between the experimental and calculated infrared spectrum shows that the present theoretical approach should provide useful data for the astrophysical models. Moreover, inertial defects calculated in the GS (ΔGS) of both molecules exhibit slightly negative values as previously observed for planar species of this molecular family. We adjusted the semi-empirical relations to estimate the zero

  10. Integration of Multisensor Remote Sensing Data for the Retrieval of Consistent Times Series of High-Resolution NDVI Images for Crop Monitoring in Landscapes Dominated By Small-Scale Farming Agricultural

    NASA Astrophysics Data System (ADS)

    Sedano, F.; Kempeneers, P.

    2014-12-01

    There is a need for timely and accurate information of food supply and early warnings of production shortfalls. Crop growth models commonly rely on information on vegetation dynamics from low and moderate spatial resolution remote sensing imagery. While the short revisit period of these sensors captures the temporal dynamics of crops, they are not able to monitor small-scale farming areas where environmental factors, crop type and management practices often vary at subpixel level. Although better suited to retrieve fine spatial structure, time series of higher resolution imagery (circa 30 m) are often incomplete due to larger revisit periods and persistent cloud coverage. However, as the Landsat archive expands and more fine resolution Earth observation sensors become available, the possibilities of multisensor integration to monitor crop dynamics with higher level of spatial detail are expanding. We have integrated remote sensing imagery from two moderate resolution sensors (MODIS and PROBA-V) and three medium resolution platforms (Landsat 7- 8; and DMC) to improve the characterization of vegetation dynamics in agricultural landscapes dominated by small-scale farms. We applied a data assimilation method to produce complete temporal sequences of synthetic medium-resolution NDVI images. The method implements a Kalman filter recursive algorithm that incorporates models, observations and their respective uncertainties to generate medium-resolution images at time steps for which only moderate-resolution imagery is available. The results for the study sites show that the time series of synthetic NDVI images captured seasonal vegetation dynamics and maintained the spatial structure of the landscape at higher spatial resolution. A more detailed characterization of spatiotemporal dynamics of vegetation in agricultural systems has the potential to improve the estimates of crop growth models and allow a more precise monitoring and forecasting of crop productivity.

  11. A Spatio-Temporal Enhancement Method for medium resolution LAI (STEM-LAI)

    NASA Astrophysics Data System (ADS)

    Houborg, Rasmus; McCabe, Matthew F.; Gao, Feng

    2016-05-01

    Satellite remote sensing has been used successfully to map leaf area index (LAI) across landscapes, but advances are still needed to exploit multi-scale data streams for producing LAI at both high spatial and temporal resolution. A multi-scale Spatio-Temporal Enhancement Method for medium resolution LAI (STEM-LAI) has been developed to generate 4-day time-series of Landsat-scale LAI from existing medium resolution LAI products. STEM-LAI has been designed to meet the demands of applications requiring frequent and spatially explicit information, such as effectively resolving rapidly evolving vegetation dynamics at sub-field (30 m) scales. In this study, STEM-LAI is applied to Moderate Resolution Imaging Spectroradiometer (MODIS) based LAI data and utilizes a reference-based regression tree approach for producing MODIS-consistent, but Landsat-based, LAI. The Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM) is used to interpolate the downscaled LAI between Landsat acquisition dates, providing a high spatial and temporal resolution improvement over existing LAI products. STARFM predicts high resolution LAI by blending MODIS and Landsat based information from a common acquisition date, with MODIS data from a prediction date. To demonstrate its capacity to reproduce fine-scale spatial features observed in actual Landsat LAI, the STEM-LAI approach is tested over an agricultural region in Nebraska. The implementation of a 250 m resolution LAI product, derived from MODIS 1 km data and using a scale consistent approach based on the Normalized Difference Vegetation Index (NDVI), is found to significantly improve accuracies of spatial pattern prediction, with the coefficient of efficiency (E) ranging from 0.77-0.94 compared to 0.01-0.85 when using 1 km LAI inputs alone. Comparisons against an 11-year record of in-situ measured LAI over maize and soybean highlight the utility of STEM-LAI in reproducing observed LAI dynamics (both characterized by r2 = 0.86) over a

  12. EVALUATING SOIL EROSION PARAMETER ESTIMATES FROM DIFFERENT DATA SOURCES

    EPA Science Inventory

    Topographic factors and soil loss estimates that were derived from thee data sources (STATSGO, 30-m DEM, and 3-arc second DEM) were compared. Slope magnitudes derived from the three data sources were consistently different. Slopes from the DEMs tended to provide a flattened sur...

  13. Visualizing sediment dynamics through repeated high-resolution multibeam mapping

    NASA Astrophysics Data System (ADS)

    de Vries, J. J.; Greinert, J.; Maierhofer, T.

    2013-12-01

    Multibeam mapping has become a common method for mapping the seafloor in shallow and great water depths with different spatial resolutions depending on the system platform (ship-based, AUV- or ROV-based), the beam angle of the system itself, the survey speed, and the distance to the seafloor. Significant advances in system accuracy, processing power and new software make multibeam mapping a powerful tool for studying sediment dynamics in 4D through repeated surveys that are ideally linked to additional studies on currents and sediment load in the water column. The Texelstroom channel, which is part of the Marsdiep between the city of Den Helder and the island of Texel (North Holland, the Netherlands), has been investigated in such a way for many years using water depth estimates from an ADCP installed on a ferry shuttling 24 times a day between the mainland and the island. Since 2009, repeated multibeam surveys have been undertaken up to three times per year as part of a student course, revealing sediment dynamics in much more detail than could be previously seen with the water depth estimates from the ferry-based ADCP. In the Texelstroom channel, the water depth ranges from a few meters to 45 meters. In the highly variable bathymetry, a series of large, bended sand waves exist mainly perpendicular to the direction of the main current. The shape of the sand waves changes from asymmetrical to symmetrical depending on the time of year, with more symmetrical shapes in spring and summer. Perpendicular to the large sand waves, smaller ripples develop during autumn. In addition to these changes in sand wave characteristics, sand wave crests sometimes migrate more than 30m in two months with an average movement of half a meter per day. The migration direction changes during the year resulting in a non-constant back-and-forth movement of the large sand waves. These intra-annual variations are characterized by changes in the slope of the sand waves, variations in the

  14. Estimating stream discharge from a Himalayan Glacier using coupled satellite sensor data

    NASA Astrophysics Data System (ADS)

    Child, S. F.; Stearns, L. A.; van der Veen, C. J.; Haritashya, U. K.; Tarpanelli, A.

    2015-12-01

    The 4th IPCC report highlighted our limited understanding of Himalayan glacier behavior and contribution to the region's hydrology. Seasonal snow and glacier melt in the Himalayas are important sources of water, but estimates greatly differ about the actual contribution of melted glacier ice to stream discharge. A more comprehensive understanding of the contribution of glaciers to stream discharge is needed because streams being fed by glaciers affect the livelihoods of a large part of the world's population. Most of the streams in the Himalayas are unmonitored because in situ measurements are logistically difficult and costly. This necessitates the use of remote sensing platforms to obtain estimates of river discharge for validating hydrological models. In this study, we estimate stream discharge using cost-effective methods via repeat satellite imagery from Landsat-8 and SENTINEL-1A sensors. The methodology is based on previous studies, which show that ratio values from optical satellite bands correlate well with measured stream discharge. While similar, our methodology relies on significantly higher resolution imagery (30 m) and utilizes bands that are in the blue and near-infrared spectrum as opposed to previous studies using 250 m resolution imagery and spectral bands only in the near-infrared. Higher resolution imagery is necessary for streams where the source is a glacier's terminus because the width of the stream is often only 10s of meters. We validate our methodology using two rivers in the state of Kansas, where stream gauges are plentiful. We then apply our method to the Bhagirathi River, in the North-Central Himalayas, which is fed by the Gangotri Glacier and has a well monitored stream gauge. The analysis will later be used to couple river discharge and glacier flow and mass balance through an integrated hydrologic model in the Bhagirathi Basin.

  15. Resolution enhancement in tilted coordinates

    NASA Astrophysics Data System (ADS)

    Hariri Naghadeh, Diako; Keith Morley, Christopher

    2016-11-01

    Deconvolution is applied to remove source wavelet effects from seismograms. The results are resolution enhancement that enables detection of thin layers. Following enhancement of resolution, low frequency and high angle reflectors, particularly at great depth, appear as low amplitude and semi-invisible reflectors that are difficult to track and pick. A new approach to enhance resolution is introduced that estimates a derivative using continuous wavelet transform in tilted coordinates. The results are compared with sparse spike deconvolution, curvelet deconvolution and inverse quality filtering in wavelet domain. The positive consequence of the new method is to increase sampling of high dip features by changing the coordinate system from Cartesian to tilted. To compare those methods a complex data set was chosen that includes high angle faults and chaotic mass transport complex. Image enhancement using curvelet deconvolution shows a chaotic system as a non-chaotic one. The results show that sparse spike deconvolution and inverse quality filtering in wavelet domain are able to enhance resolution more than curvelet deconvolution especially at great depth but it is impossible to follow steep dip reflectors after resolution enhancement using these methods, especially when their apparent dips are more than 45°. By estimating derivatives in a continuous wavelet transform from tilted data sets similar resolution enhancement as the other deconvolution methods is achieved but additionally steep dipping reflectors are imaged much better than others. Subtracted results of the enhanced resolution data set using new method and the other introduced methods show that steeply dipping reflectors are highlighted as a particular ability of the new method. The results show that high frequency recovery in Cartesian co-ordinate is accompanied by inability to image steeply dipping reflectors especially at great depths. Conversely recovery of high frequency data and imaging of the data

  16. Deriving Continuous Fields of Tree Cover at 1-m over the Continental United States From the National Agriculture Imagery Program (NAIP) Imagery to Reduce Uncertainties in Forest Carbon Stock Estimation

    NASA Astrophysics Data System (ADS)

    Ganguly, S.; Basu, S.; Mukhopadhyay, S.; Michaelis, A.; Milesi, C.; Votava, P.; Nemani, R. R.

    2013-12-01

    An unresolved issue with coarse-to-medium resolution satellite-based forest carbon mapping over regional to continental scales is the high level of uncertainty in above ground biomass (AGB) estimates caused by the absence of forest cover information at a high enough spatial resolution (current spatial resolution is limited to 30-m). To put confidence in existing satellite-derived AGB density estimates, it is imperative to create continuous fields of tree cover at a sufficiently high resolution (e.g. 1-m) such that large uncertainties in forested area are reduced. The proposed work will provide means to reduce uncertainty in present satellite-derived AGB maps and Forest Inventory and Analysis (FIA) based regional estimates. Our primary objective will be to create Very High Resolution (VHR) estimates of tree cover at a spatial resolution of 1-m for the Continental United States using all available National Agriculture Imaging Program (NAIP) color-infrared imagery from 2010 till 2012. We will leverage the existing capabilities of the NASA Earth Exchange (NEX) high performance computing and storage facilities. The proposed 1-m tree cover map can be further aggregated to provide percent tree cover at any medium-to-coarse resolution spatial grid, which will aid in reducing uncertainties in AGB density estimation at the respective grid and overcome current limitations imposed by medium-to-coarse resolution land cover maps. We have implemented a scalable and computationally-efficient parallelized framework for tree-cover delineation - the core components of the algorithm [that] include a feature extraction process, a Statistical Region Merging image segmentation algorithm and a classification algorithm based on Deep Belief Network and a Feedforward Backpropagation Neural Network algorithm. An initial pilot exercise has been performed over the state of California (~11,000 scenes) to create a wall-to-wall 1-m tree cover map and the classification accuracy has been assessed

  17. High-Resolution Modeling Disturbance-Induced Forest Carbon Dynamics with Lidar and Landsat Observations

    NASA Astrophysics Data System (ADS)

    Zhao, M.; Huang, C.; Hurtt, G. C.; Dubayah, R.; Fisk, J.; Sahajpal, R.; Flanagan, S.; Swatantran, A.; Huang, W.; Tang, H.; ONeil-Dunne, J.; Johnson, K. D.

    2015-12-01

    Forest stands are dynamic in a status from severely, partially disturbed, or undisturbed to different stages of recovery towards maturity and equilibrium. Forest ecosystem models generally use potential biomass (an assumption of equilibrium status) as initial biomass, which is unrealistic and could result in unreliable estimates of disturbance-induced carbon changes. To accurately estimate spatiotemporal changes of forest carbon stock and fluxes, it requires accurate information on initial biomass, the extent and severity of disturbance, and following land use. We demonstrate a prototype system to achieve this goal by integrating 1-m small footprint Lidar acquired in year 2004, 30-m Landsat disturbances from 1984 to 2011, and an individual-based structure height Ecosystem Demography (ED) model. Lidar provides critical information on forest canopy height, improving the accuracy of initial forest biomass estimates; impervious surfaces data and yearly disturbance data from Landsat provide information on wall-to-wall yearly natural and anthropogenic disturbances and their severity (on average 0.32% for the natural and 0.19% for the anthropogenic for below test area); ED model plays a central role by linking both Lidar canopy height and Landsat disturbances with ecosystem processes. We tested the system at 90-m spatial resolution in Charles County, Maryland, by running ED model for six experiments, the combinations of three initial biomass (potential, moderate and low initial biomass constrained by Lidar canopy height) with two disturbance scenarios (with and without anthropogenic disturbances). Our experiments show that estimated changes of carbon stock and flux are sensitive to initial biomass status and human-induced land cover change. Our prototype system can assess regional carbon dynamics at local scale under changing climate and disturbance regimes, and provide useful information for forest management and land use policies.

  18. Numerical Estimation in Preschoolers

    ERIC Educational Resources Information Center

    Berteletti, Ilaria; Lucangeli, Daniela; Piazza, Manuela; Dehaene, Stanislas; Zorzi, Marco

    2010-01-01

    Children's sense of numbers before formal education is thought to rely on an approximate number system based on logarithmically compressed analog magnitudes that increases in resolution throughout childhood. School-age children performing a numerical estimation task have been shown to increasingly rely on a formally appropriate, linear…

  19. Resolution in Electromagnetic Prospecting

    NASA Astrophysics Data System (ADS)

    Aldridge, D. F.; Bartel, L. C.; Knox, H. A.; Schramm, K. A.

    2014-12-01

    Low-frequency electromagnetic (EM) signals are commonly used in geophysical exploration of the shallow subsurface. Sensitivity to conductivity implies they are particularly useful for inferring fluid content of porous media. However, low-frequency EM wavefields are diffusive, and have significantly larger wavelengths compared to seismic signals of equal frequency. The wavelength of a 30 Hz sinusoid propagating with seismic velocity 3000 m/s is 100 m, whereas an analogous EM signal diffusing through a conductive body of 0.1 S/m (clayey shale) has wavelength 1825 m. The larger wavelength has implications for resolution of the EM prospecting method. We are investigating resolving power of the EM method via theoretical and numerical experiments. Normal incidence plane wave reflection/transmission by a thin geologic bed is amenable to analytic solution. Responses are calculated for beds that are conductive or resistive relative to the host rock. Preliminary results indicate the classic seismic resolution/detection limit of bed thickness ~1/8 wavelength is not achieved. EM responses for point or line current sources recorded by general acquisition geometries are calculated with a 3D finite-difference algorithm. These exhibit greater variability which may allow inference of bed thickness. We also examine composite responses of two point scatterers with separation when illuminated by an incident EM field. This is analogous to the Rayleigh resolution problem of estimating angular separation between two light sources. The First Born Approximation implies that perturbations in permittivity, permeability, and conductivity have different scattering patterns, which may be indicators of EM medium properties. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  20. Multivariate curve resolution-alternating least squares and kinetic modeling applied to near-infrared data from curing reactions of epoxy resins: mechanistic approach and estimation of kinetic rate constants.

    PubMed

    Garrido, M; Larrechi, M S; Rius, F X

    2006-02-01

    This study describes the combination of multivariate curve resolution-alternating least squares with a kinetic modeling strategy for obtaining the kinetic rate constants of a curing reaction of epoxy resins. The reaction between phenyl glycidyl ether and aniline is monitored by near-infrared spectroscopy under isothermal conditions for several initial molar ratios of the reagents. The data for all experiments, arranged in a column-wise augmented data matrix, are analyzed using multivariate curve resolution-alternating least squares. The concentration profiles recovered are fitted to a chemical model proposed for the reaction. The selection of the kinetic model is assisted by the information contained in the recovered concentration profiles. The nonlinear fitting provides the kinetic rate constants. The optimized rate constants are in agreement with values reported in the literature.

  1. Distribution of Near-Surface Permafrost in Alaska: Estimates of Present and Future Conditions

    NASA Astrophysics Data System (ADS)

    Pastick, N.; Jorgenson, T.; Wylie, B. K.; Nield, S.; Johnson, K. D.; Finley, A.

    2014-12-01

    High-latitude regions are experiencing rapid and extensive changes in ecosystem composition and function as the result of increases in average air temperature. Increasing air temperatures have led to widespread thawing and degradation of permafrost, which in turn has affected ecosystems, socioeconomics, and the carbon cycle of high latitudes. Further warming could lead to increasing ground temperatures, thickening active-layers, and accelerated thawing and degradation of permafrost. Despite permafrost's influence on ecosystem structure and functions, relatively little has been done to quantify permafrost properties across extremely large areas and at high resolutions. Detection and mapping of permafrost are difficult, however, because it is a subsurface condition of the ground, heterogeneous in nature, and largely exists in remote locations. Here we overcome complex interactions among surface and subsurface conditions to map permafrost through empirical modeling approaches that statistically and spatially extend field observations using remotely sensed imagery, climatic data, and thematic maps of a wide range of surface and subsurface biophysical characteristics. The data fusion approach generated high-resolution (30-m pixels) maps of near-surface (within 1 m) permafrost, active-layer thickness, and associated uncertainty estimates throughout most of Alaska. Our calibrated models were then used to quantify changes in permafrost distribution under varying future climate scenarios assuming no other changes in biophysical factors. The mapping of permafrost distribution across Alaska is important for land-use planning, environmental assessments, and a wide-array of geophysical studies.

  2. Lidar-derived estimate and uncertainty of carbon sink in successional phases of woody encroachment

    NASA Astrophysics Data System (ADS)

    Sankey, Temuulen; Shrestha, Rupesh; Sankey, Joel B.; Hardegree, Stuart; Strand, Eva

    2013-07-01

    encroachment is a globally occurring phenomenon that contributes to the global carbon sink. The magnitude of this contribution needs to be estimated at regional and local scales to address uncertainties present in the global- and continental-scale estimates, and guide regional policy and management in balancing restoration activities, including removal of woody plants, with greenhouse gas mitigation goals. The objective of this study was to estimate carbon stored in various successional phases of woody encroachment. Using lidar measurements of individual trees, we present high-resolution estimates of aboveground carbon storage in juniper woodlands. Segmentation analysis of lidar point cloud data identified a total of 60,628 juniper tree crowns across four watersheds. Tree heights, canopy cover, and density derived from lidar were strongly correlated with field measurements of 2613 juniper stems measured in 85 plots (30 × 30 m). Aboveground total biomass of individual trees was estimated using a regression model with lidar-derived height and crown area as predictors (Adj. R2 = 0.76, p < 0.001, RMSE = 0.58 kg). The predicted mean aboveground woody carbon storage for the study area was 677 g/m2. Uncertainty in carbon storage estimates was examined with a Monte Carlo approach that addressed major error sources. Ranges predicted with uncertainty analysis in the mean, individual tree, aboveground woody C, and associated standard deviation were 0.35 - 143.6 kg and 0.5 - 1.25 kg, respectively. Later successional phases of woody encroachment had, on average, twice the aboveground carbon relative to earlier phases. Woody encroachment might be more successfully managed and balanced with carbon storage goals by identifying priority areas in earlier phases of encroachment where intensive treatments are most effective.

  3. Daily Landsat-scale evapotranspiration estimation over a forested landscape in North Carolina, USA, using multi-satellite data fusion

    NASA Astrophysics Data System (ADS)

    Yang, Yun; Anderson, Martha C.; Gao, Feng; Hain, Christopher R.; Semmens, Kathryn A.; Kustas, William P.; Noormets, Asko; Wynne, Randolph H.; Thomas, Valerie A.; Sun, Ge

    2017-02-01

    As a primary flux in the global water cycle, evapotranspiration (ET) connects hydrologic and biological processes and is directly affected by water and land management, land use change and climate variability. Satellite remote sensing provides an effective means for diagnosing ET patterns over heterogeneous landscapes; however, limitations on the spatial and temporal resolution of satellite data, combined with the effects of cloud contamination, constrain the amount of detail that a single satellite can provide. In this study, we describe an application of a multi-sensor ET data fusion system over a mixed forested/agricultural landscape in North Carolina, USA, during the growing season of 2013. The fusion system ingests ET estimates from the Two-Source Energy Balance Model (TSEB) applied to thermal infrared remote sensing retrievals of land surface temperature from multiple satellite platforms: hourly geostationary satellite data at 4 km resolution, daily 1 km imagery from the Moderate Resolution Imaging Spectroradiometer (MODIS) and biweekly Landsat thermal data sharpened to 30 m. These multiple ET data streams are combined using the Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM) to estimate daily ET at 30 m resolution to investigate seasonal water use behavior at the level of individual forest stands and land cover patches. A new method, also exploiting the STARFM algorithm, is used to fill gaps in the Landsat ET retrievals due to cloud cover and/or the scan-line corrector (SLC) failure on Landsat 7. The retrieved daily ET time series agree well with observations at two AmeriFlux eddy covariance flux tower sites in a managed pine plantation within the modeling domain: US-NC2 located in a mid-rotation (20-year-old) loblolly pine stand and US-NC3 located in a recently clear-cut and replanted field site. Root mean square errors (RMSEs) for NC2 and NC3 were 0.99 and 1.02 mm day-1, respectively, with mean absolute errors of approximately 29 % at the

  4. Estimation of daily Snow Cover Area combining MODIS and LANDSAT information by using cellular automata

    NASA Astrophysics Data System (ADS)

    Pardo-Iguzquiza, Eulogio; Juan Collados Lara, Antonio; Pulido-Velazquez, David

    2016-04-01

    The snow availability in Alpine catchments is essential for the economy of these areas. It plays an important role in tourist development but also in the management of the Water Resources Snow is an important water resource in many river basins with mountains in the catchment area. The determination of the snow water equivalent requires the estimation of the evolution of the snow pack (cover area, thickness and snow density) along the time. Although there are complex physical models of the dynamics of the snow pack, sometimes the data available are scarce and a stochastic model like the cellular automata (CA) can be of great practical interest. CA can be used to model the dynamics of growth and wane of the snow pack. The CA is calibrated with historical data. This requires the determination of transition rules that are capable of modeling the evolution of the spatial pattern of snow cover area. Furthermore, CA requires the definition of states and neighborhoods. We have included topographical variables and climatological variables in order to define the state of each pixel. The evolution of snow cover in a pixel depends on its state, the state of the neighboring pixels and the transition rules. The calibration of the CA is done using daily MODIS data, available for the period 24/02/2002 to present with a spatial resolution of 500 m, and the LANDSAT information available with a sixteen-day periodicity from 1984 to the present and with spatial resolution of 30 m. The methodology has been applied to estimation of the snow cover area of Sierra Nevada mountain range in the Southern of Spain to obtain snow cover area daily information with 500 m spatial resolution for the period 1980-2014. Acknowledgments: This research has been partially supported by the GESINHIMPADAPT project (CGL2013-48424-C2-2-R) with Spanish MINECO funds. We would also like to thank NASA DAAC and LANDSAT project for the data provided for this study.

  5. Resolution in forensic microbial genotyping

    SciTech Connect

    Velsko, S P

    2005-08-30

    Resolution is a key parameter for differentiating among the large number of strain typing methods that could be applied to pathogens involved in bioterror events or biocrimes. In this report we develop a first-principles analysis of strain typing resolution using a simple mathematical model to provide a basis for the rational design of microbial typing systems for forensic applications. We derive two figures of merit that describe the resolving power and phylogenetic depth of a strain typing system. Rough estimates of these figures-of-merit for MLVA, MLST, IS element, AFLP, hybridization microarrays, and other bacterial typing methods are derived from mutation rate data reported in the literature. We also discuss the general problem of how to construct a ''universal'' practical typing system that has the highest possible resolution short of whole-genome sequencing, and that is applicable with minimal modification to a wide range of pathogens.

  6. A novel method to retrieve Aerosol Optical Thickness from high-resolution optical satellite images using an extended version of the Haze Optimized Transform (HOTBAR)

    NASA Astrophysics Data System (ADS)

    Wilson, Robin; Milton, Edward; Nield, Joanna

    2016-04-01

    Aerosol Optical Thickness (AOT) data has many important applications including atmospheric correction of satellite imagery and monitoring of particulate matter air pollution. Current data products are generally available at a kilometre-scale resolution, but many applications require far higher resolutions. For example, particulate matter concentrations vary on a metre-scale, and thus data products at a similar scale are required to provide accurate assessments of particle densities and allow effective monitoring of air quality and analysis of local air quality effects on health. A novel method has been developed which retrieves per-pixel AOT values from high-resolution (~30m) satellite data. This method is designed to work over a wide range of land covers - including both bright and dark surfaces - and requires only standard visible and near-infrared data, making it applicable to a range of data from sensors such as Landsat, SPOT and Sentinel-2. The method is based upon an extension of the Haze Optimized Transform (HOT). The HOT was originally designed for assessing areas of thick haze in satellite imagery by calculating a 'haziness' value for each pixel in an image as the distance from a 'Clear Line' in feature space, defined by the high correlation between visible bands. Here, we adapt the HOT method and use it to provide AOT data instead. Significant extensions include Monte Carlo estimation of the 'Clear Line', object-based correction for land cover, and estimation of AOT from the haziness values through radiative transfer modelling. This novel method will enable many new applications of AOT data that were impossible with previously available low-resolution data, and has the potential to contribute significantly to our understanding of the air quality on health, the accuracy of satellite image atmospheric correction and the role of aerosols in the climate system.

  7. Estimating aboveground forest biomass carbon and fire consumption in the U.S. Utah High Plateaus using data from the Forest Inventory and Analysis program, Landsat, and LANDFIRE

    USGS Publications Warehouse

    Chen, X.; Liu, S.; Zhu, Z.; Vogelmann, J.; Li, Z.; Ohlen, D.

    2011-01-01

    The concentrations of CO2 and other greenhouse gases in the atmosphere have been increasing and greatly affecting global climate and socio-economic systems. Actively growing forests are generally considered to be a major carbon sink, but forest wildfires lead to large releases of biomass carbon into the atmosphere. Aboveground forest biomass carbon (AFBC), an important ecological indicator, and fire-induced carbon emissions at regional scales are highly relevant to forest sustainable management and climate change. It is challenging to accurately estimate the spatial distribution of AFBC across large areas because of the spatial heterogeneity of forest cover types and canopy structure. In this study, Forest Inventory and Analysis (FIA) data, Landsat, and Landscape Fire and Resource Management Planning Tools Project (LANDFIRE) data were integrated in a regression tree model for estimating AFBC at a 30-m resolution in the Utah High Plateaus. AFBC were calculated from 225 FIA field plots and used as the dependent variable in the model. Of these plots, 10% were held out for model evaluation with stratified random sampling, and the other 90% were used as training data to develop the regression tree model. Independent variable layers included Landsat imagery and the derived spectral indicators, digital elevation model (DEM) data and derivatives, biophysical gradient data, existing vegetation cover type and vegetation structure. The cross-validation correlation coefficient (r value) was 0.81 for the training model. Independent validation using withheld plot data was similar with r value of 0.82. This validated regression tree model was applied to map AFBC in the Utah High Plateaus and then combined with burn severity information to estimate loss of AFBC in the Longston fire of Zion National Park in 2001. The final dataset represented 24 forest cover types for a 4 million ha forested area. We estimated a total of 353 Tg AFBC with an average of 87 MgC/ha in the Utah High

  8. Using high spatial resolution satellite imagery to map forest burn severity across spatial scales in a Pine Barrens ecosystem

    DOE PAGES

    Meng, Ran; Wu, Jin; Schwager, Kathy L.; ...

    2017-01-21

    As a primary disturbance agent, fire significantly influences local processes and services of forest ecosystems. Although a variety of remote sensing based approaches have been developed and applied to Landsat mission imagery to infer burn severity at 30 m spatial resolution, forest burn severity have still been seldom assessed at fine spatial scales (≤ 5 m) from very-high-resolution (VHR) data. Here we assessed a 432 ha forest fire that occurred in April 2012 on Long Island, New York, within the Pine Barrens region, a unique but imperiled fire-dependent ecosystem in the northeastern United States. The mapping of forest burn severitymore » was explored here at fine spatial scales, for the first time using remotely sensed spectral indices and a set of Multiple Endmember Spectral Mixture Analysis (MESMA) fraction images from bi-temporal — pre- and post-fire event — WorldView-2 (WV-2) imagery at 2 m spatial resolution. We first evaluated our approach using 1 m by 1 m validation points at the sub-crown scale per severity class (i.e. unburned, low, moderate, and high severity) from the post-fire 0.10 m color aerial ortho-photos; then, we validated the burn severity mapping of geo-referenced dominant tree crowns (crown scale) and 15 m by 15 m fixed-area plots (inter-crown scale) with the post-fire 0.10 m aerial ortho-photos and measured crown information of twenty forest inventory plots. Our approach can accurately assess forest burn severity at the sub-crown (overall accuracy is 84% with a Kappa value of 0.77), crown (overall accuracy is 82% with a Kappa value of 0.76), and inter-crown scales (89% of the variation in estimated burn severity ratings (i.e. Geo-Composite Burn Index (CBI)). Lastly, this work highlights that forest burn severity mapping from VHR data can capture heterogeneous fire patterns at fine spatial scales over the large spatial extents. This is important since most ecological processes associated with fire effects vary at the < 30 m scale and

  9. Singlet oxygen photosensitisation by the fluorescent protein Pp2FbFP L30M, a novel derivative of Pseudomonas putida flavin-binding Pp2FbFP.

    PubMed

    Torra, Joaquim; Burgos-Caminal, Andrés; Endres, Stephan; Wingen, Marcus; Drepper, Thomas; Gensch, Thomas; Ruiz-González, Rubén; Nonell, Santi

    2015-02-01

    Flavin-binding fluorescent proteins (FbFPs) are a class of fluorescent reporters that have been increasingly used as reporters in the study of cellular structures and dynamics. Flavin's intrinsic high singlet oxygen ((1)O2) quantum yield (ΦΔ = 0.51) provides a basis for the development of new FbFP mutants capable of photosensitising (1)O2 for mechanistic and therapeutic applications, as recently exemplified by the FbFP miniSOG. In the present work we report an investigation on the (1)O2 photoproduction by Pp2FbFP L30M, a novel derivative of Pseudomonas putida Pp2FbFP. Direct detection of (1)O2 through its phosphorescence at 1275 nm yielded the value ΦΔ = 0.09 ± 0.01, which is the highest (1)O2 quantum yield reported to date for any FP and is approximately 3-fold higher than the ΦΔ for miniSOG. Unlike miniSOG, transient absorption measurements revealed the existence of two independent triplet states each with a different ability to sensitise (1)O2.

  10. Remote sensing estimates of stand-replacement fires in Russia, 2002-2011

    NASA Astrophysics Data System (ADS)

    Krylov, Alexander; McCarty, Jessica L.; Potapov, Peter; Loboda, Tatiana; Tyukavina, Alexandra; Turubanova, Svetlana; Hansen, Matthew C.

    2014-10-01

    The presented study quantifies the proportion of stand-replacement fires in Russian forests through the integrated analysis of Landsat and Moderate Resolution Imaging Spectroradiometer (MODIS) data products. We employed 30 m Landsat Enhanced Thematic Mapper Plus derived tree canopy cover and decadal (2001-2012) forest cover loss (Hansen et al 2013 High-resolution global maps of 21st-century forest cover change Science 342 850-53) to identify forest extent and disturbance. These data were overlaid with 1 km MODIS active fire (earthdata.nasa.gov/data/near-real-time-data/firms) and 500 m regional burned area data (Loboda et al 2007 Regionally adaptable dNBR-based algorithm for burned area mapping from MODIS data Remote Sens. Environ. 109 429-42 and Loboda et al 2011 Mapping burned area in Alaska using MODIS data: a data limitations-driven modification to the regional burned area algorithm Int. J. Wildl. Fire 20 487-96) to differentiate stand-replacement disturbances due to fire versus other causes. Total stand replacement forest fire area within the Russian Federation from 2002 to 2011 was estimated to be 17.6 million ha (Mha). The smallest stand-replacement fire loss occurred in 2004 (0.4 Mha) and the largest annual loss in 2003 (3.3 Mha). Of total burned area within forests, 33.6% resulted in stand-replacement. Light conifer stands comprised 65% of all non-stand-replacement and 79% of all stand-replacement fire in Russia. Stand-replacement area for the study period is estimated to be two times higher than the reported logging area. Results of this analysis can be used with historical fire regime estimations to develop effective fire management policy, increase accuracy of carbon calculations, and improve fire behavior and climate change modeling efforts.

  11. Exploring multi-scale forest above ground biomass estimation with optical remote sensing imageries

    NASA Astrophysics Data System (ADS)

    Koju, U.; Zhang, J.; Gilani, H.

    2017-02-01

    Forest shares 80% of total exchange of carbon between the atmosphere and the terrestrial ecosystem. Due to this monitoring of forest above ground biomass (as carbon can be calculated as 0.47 part of total biomass) has become very important. Forest above ground biomass as being the major portion of total forest biomass should be given a very careful consideration in its estimation. It is hoped to be useful in addressing the ongoing problems of deforestation and degradation and to gain carbon mitigation benefits through mechanisms like Reducing Emissions from Deforestation and Forest Degradation (REDD+). Many methods of above ground biomass estimation are in used ranging from use of optical remote sensing imageries of very high to very low resolution to SAR data and LIDAR. This paper describes a multi-scale approach for assessing forest above ground biomass, and ultimately carbon stocks, using very high imageries, open source medium resolution and medium resolution satellite datasets with a very limited number of field plots. We found this method is one of the most promising method for forest above ground biomass estimation with higher accuracy and low cost budget. Pilot study was conducted in Chitwan district of Nepal on the estimation of biomass using this technique. The GeoEye-1 (0.5m), Landsat (30m) and Google Earth (GE) images were used remote sensing imageries. Object-based image analysis (OBIA) classification technique was done on Geo-eye imagery for the tree crown delineation at the watershed level. After then, crown projection area (CPA) vs. biomass model was developed and validated at the watershed level. Open source GE imageries were used to calculate the CPA and biomass from virtual plots at district level. Using data mining technique, different parameters from Landsat imageries along with the virtual sample biomass were used for upscaling biomass estimation at district level. We found, this approach can considerably reduce field data requirements for

  12. Estimating aboveground biomass in interior Alaska with Landsat data and field measurements

    USGS Publications Warehouse

    Ji, Lei; Wylie, Bruce K.; Nossov, Dana R.; Peterson, Birgit E.; Waldrop, Mark P.; McFarland, Jack W.; Rover, Jennifer R.; Hollingsworth, Teresa N.

    2012-01-01

    Terrestrial plant biomass is a key biophysical parameter required for understanding ecological systems in Alaska. An accurate estimation of biomass at a regional scale provides an important data input for ecological modeling in this region. In this study, we created an aboveground biomass (AGB) map at 30-m resolution for the Yukon Flats ecoregion of interior Alaska using Landsat data and field measurements. Tree, shrub, and herbaceous AGB data in both live and dead forms were collected in summers and autumns of 2009 and 2010. Using the Landsat-derived spectral variables and the field AGB data, we generated a regression model and applied this model to map AGB for the ecoregion. A 3-fold cross-validation indicated that the AGB estimates had a mean absolute error of 21.8 Mg/ha and a mean bias error of 5.2 Mg/ha. Additionally, we validated the mapping results using an airborne lidar dataset acquired for a portion of the ecoregion. We found a significant relationship between the lidar-derived canopy height and the Landsat-derived AGB (R2 = 0.40). The AGB map showed that 90% of the ecoregion had AGB values ranging from 10 Mg/ha to 134 Mg/ha. Vegetation types and fires were the primary factors controlling the spatial AGB patterns in this ecoregion.

  13. Using lidar and effective LAI data to evaluate IKONOS and Landsat 7 ETM+ vegetation cover estimates in a ponderosa pine forest

    USGS Publications Warehouse

    Chen, X.; Vierling, Lee; Rowell, E.; DeFelice, Tom

    2004-01-01

    Structural and functional analyses of ecosystems benefit when high accuracy vegetation coverages can be derived over large areas. In this study, we utilize IKONOS, Landsat 7 ETM+, and airborne scanning light detection and ranging (lidar) to quantify coniferous forest and understory grass coverages in a ponderosa pine (Pinus ponderosa) dominated ecosystem in the Black Hills of South Dakota. Linear spectral mixture analyses of IKONOS and ETM+ data were used to isolate spectral endmembers (bare soil, understory grass, and tree/shade) and calculate their subpixel fractional coverages. We then compared these endmember cover estimates to similar cover estimates derived from lidar data and field measures. The IKONOS-derived tree/shade fraction was significantly correlated with the field-measured canopy effective leaf area index (LAIe) (r2=0.55, p<0.001) and with the lidar-derived estimate of tree occurrence (r2=0.79, p<0.001). The enhanced vegetation index (EVI) calculated from IKONOS imagery showed a negative correlation with the field measured tree canopy effective LAI and lidar tree cover response (r 2=0.30, r=-0.55 and r2=0.41, r=-0.64, respectively; p<0.001) and further analyses indicate a strong linear relationship between EVI and the IKONOS-derived grass fraction (r2=0.99, p<0.001). We also found that using EVI resulted in better agreement with the subpixel vegetation fractions in this ecosystem than using normalized difference of vegetation index (NDVI). Coarsening the IKONOS data to 30 m resolution imagery revealed a stronger relationship with lidar tree measures (r2=0.77, p<0.001) than at 4 m resolution (r2=0.58, p<0.001). Unmixed tree/shade fractions derived from 30 m resolution ETM+ imagery also showed a significant correlation with the lidar data (r2=0.66, p<0.001). These results demonstrate the power of using high resolution lidar data to validate spectral unmixing results of satellite imagery, and indicate that IKONOS data and Landsat 7 ETM+ data both can

  14. A high-resolution bathymetric survey of the Vernago reservoir, Eastern Italian Alps

    NASA Astrophysics Data System (ADS)

    Brardinoni, Francesco; Marchese, Fabio; Villa, Alberto; Macconi, Pierpaolo; Savini, Alessandra

    2015-04-01

    Artificial reservoirs for hydropower production disrupt the river hydro-geomorphic continuity in Alpine basins and constitute efficient sediment traps. In so doing they strongly change upstream and dowstream fluvial morphodynamics, hence alter riverine habitat conditions. Managing the surplus of sediment deposited in the reservoir, which is deducted to the natural sediment budget of the downstream channel reaches, represents one of the key components for the sustainable management of Alpine drainage basins. At the same time, in-lake siltation rates can be used as proxy for sediment yield at the outlet of a given study basin, and therefore can provide useful quantitative information on landscape downwasting. In this context, a first critical step lies in the quantification of the boundary conditions characterizing the bottom of the reservoir. To this end we present the results of a high-resolution bathymetric survey of the Vernago reservoir, Senales Valley, Italy. The bathymetry has been acquired by means of SEA Swathplus interferometric sonar mounted on a 4.30 m boat. This lightweight device is particularly well-suited for working within Alpine reservoirs in that it ensures wide swath width (up to 150 m) in shallow water (down to 50 m) and high resolution (0.03 m) up to the swath edge. Data post-processing allow building a 1m-grid DEM of the reservoir floor through which we are able to resolve the geomorphic variability characterizing tributary fans, man-made subaqueous canals, areas of active deposition, and newly formed natural subaqueous channels. Future work will involve performing a DoD (DEM of difference) between the bathymetric-derived DEM and pre-reservoir topography (i.e., 1962) in order to obtain a first-order estimate of sedimentation patterns. This work is part of SedAlp (www.sedalp.eu), a project funded through the Alpine Space Programme.

  15. Estimating the spatial distribution of PM2.5 concentration by integrating geographic data and field measurements

    NASA Astrophysics Data System (ADS)

    Zhai, L.; Sang, H.; Zhang, J.; An, F.

    2015-06-01

    Air quality directly affects the health and living of human beings, and it receives wide concern of public and attaches great important of governments at all levels. The estimation of the concentration distribution of PM2.5 and the analysis of its impacting factors is significant for understanding the spatial distribution regularity and further for decision supporting of governments. In this study, multiple sources of remote sensing and GIS data are utilized to estimate the spatial distribution of PM2.5 concentration in Shijiazhuang, China, by utilizing multivariate linear regression modelling, and integrating year average values of PM2.5 collected from local environment observing stations. Two major sources of PM2.5 are collected, including dust surfaces and industrial polluting sources. The area attribute of dust surfaces and point attribute of industrial polluting enterprises are extracted from high resolution remote sensing images and GIS data in 2013. 30m land cover products, annual average PM2.5 concentration values from the 8 environment monitoring stations, annual mean MODIS AOD data, traffic and DEM data are utilized in the study for regression modeling analysis. The multivariate regression analysis model is applied to estimate the spatial distribution of PM2.5 concentration. There is an upward trend of the spatial distribution of PM2.5 concentration gradually from west to east, of which the highest concentration appears in the municipal district and its surrounding areas. The spatial distribution pattern relatively fit the reality.

  16. Generalizing the nonlocal-means to super-resolution reconstruction.

    PubMed

    Protter, Matan; Elad, Michael; Takeda, Hiroyuki; Milanfar, Peyman

    2009-01-01

    Super-resolution reconstruction proposes a fusion of several low-quality images into one higher quality result with better optical resolution. Classic super-resolution techniques strongly rely on the availability of accurate motion estimation for this fusion task. When the motion is estimated inaccurately, as often happens for nonglobal motion fields, annoying artifacts appear in the super-resolved outcome. Encouraged by recent developments on the video denoising problem, where state-of-the-art algorithms are formed with no explicit motion estimation, we seek a super-resolution algorithm of similar nature that will allow processing sequences with general motion patterns. In this paper, we base our solution on the Nonlocal-Means (NLM) algorithm. We show how this denoising method is generalized to become a relatively simple super-resolution algorithm with no explicit motion estimation. Results on several test movies show that the proposed method is very successful in providing super-resolution on general sequences.

  17. Estimating landscape carrying capacity through maximum clique analysis.

    PubMed

    Donovan, Therese M; Warrington, Gregory S; Schwenk, W Scott; Dinitz, Jeffrey H

    2012-12-01

    Habitat suitability (HS) maps are widely used tools in wildlife science and establish a link between wildlife populations and landscape pattern. Although HS maps spatially depict the distribution of optimal resources for a species, they do not reveal the population size a landscape is capable of supporting--information that is often crucial for decision makers and managers. We used a new approach, "maximum clique analysis," to demonstrate how HS maps for territorial species can be used to estimate the carrying capacity, N(k), of a given landscape. We estimated the N(k) of Ovenbirds (Seiurus aurocapillus) and bobcats (Lynx rufus) in an 1153-km2 study area in Vermont, USA. These two species were selected to highlight different approaches in building an HS map as well as computational challenges that can arise in a maximum clique analysis. We derived 30-m2 HS maps for each species via occupancy modeling (Ovenbird) and by resource utilization modeling (bobcats). For each species, we then identified all pixel locations on the map (points) that had sufficient resources in the surrounding area to maintain a home range (termed a "pseudo-home range"). These locations were converted to a mathematical graph, where any two points were linked if two pseudo-home ranges could exist on the landscape without violating territory boundaries. We used the program Cliquer to find the maximum clique of each graph. The resulting estimates of N(k) = 236 Ovenbirds and N(k) = 42 female bobcats were sensitive to different assumptions and model inputs. Estimates of N(k) via alternative, ad hoc methods were 1.4 to > 30 times greater than the maximum clique estimate, suggesting that the alternative results may be upwardly biased. The maximum clique analysis was computationally intensive but could handle problems with < 1500 total pseudo-home ranges (points). Given present computational constraints, it is best suited for species that occur in clustered distributions (where the problem can be

  18. High resolution applications of seismic tomography: low velocity anomalies and static corrections using wave-equation datuming

    NASA Astrophysics Data System (ADS)

    Flecha, I.; Marti, D.; Escuder, J.; Perez-Estaun, A.; Carbonell, R.

    2003-04-01

    A detailed characterization of the internal structure and physical properties of shallow surface can be obtained using high-resolution seismic tomography. Two applications of high resolution seismic tomography are presented in this study. Several synthetics simulations have been carried out to asses the resolving power of this methodology in different cases. The first studied case is the detection of low velocity anomalies in the shallow subsoil. Underground cavities (mines), water flows (formation wich loose sand), etc., are geological features present in the shallow subsurface characterized by low seismic velocities, and are targets of considerable social interest. We have considered a 400m×50m two dimensional velocity model consisting of a background velocity gradient in depth from 3 to 4 Km/s which included a rectangular low velocity anomaly (300 m/s). This anomaly was placed between 10m and 30m in depth and between 180m and 220m in length. The inversions schemes provided estimates of the velocity, however the tomograms and the ray tracing diagrams indicated a low resolution for the anomaly. In the second case we have applied wave-equation datuming to pre-stack layer replacement. The standard seismic data processing app