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Sample records for small-scale spatial variability

  1. Small-Scale Spatial Variability of Ozone in Boulder, Colorado

    NASA Astrophysics Data System (ADS)

    Deanes, L. N.; Sadighi, K.; Casey, J. G.; Collier, A. M.; Hannigan, M.

    2015-12-01

    Surface ozone (O3) can pose several health risks to humans, such as an increased number of and intensity of asthma attacks. Considering this, it is important that ozone levels are monitored. While municipal air quality monitors are present in cities like Boulder, Colorado, these monitors often only consider regional analysis, neglecting the variability of compounds, such as ozone or carbon monoxide, over smaller distances. Small-scale (approximately 1 kilometer) spatial variability in ozone is important because humans experience these small scales on a daily basis. Using low-cost, next-generation air quality monitors ("pods") developed at the University of Colorado-Boulder, we assessed small-scale spatial variability of surface ozone in Boulder, Colorado. This was done by placing clusters of 4-5 pods within approximately 1 kilometer of each other at specific sites in the city of Boulder. We collected data at two sites: one on the University of Colorado-Boulder campus (i.e., an urban site) and one outside of the city (i.e., a rural site). Pods were left in their positions for one to two weeks allowing for observation of ozone trends. As expected the typical diurnal trend was observed; however, further analysis revealed differences between these daily trends. Data collected by the pods allows for better understanding of small-scale spatial variability of surface ozone and how this may be driven by nearby sources.

  2. Small-Scale Spatial Variability of Ice Supersaturation and Cirrus in the TTL

    NASA Astrophysics Data System (ADS)

    DiGangi, J. P.; Podolske, J. R.; Rana, M.; Slate, T. A.; Diskin, G. S.

    2014-12-01

    The processes controlling cloud formation and evolution represent a significant uncertainty in models of global climate change. High altitude cirrus clouds contribute a large portion of this uncertainty due to their altitude and abundance. The mechanism behind the formation of cirrus clouds depends on the characteristics and composition of ice supersaturation (ISS) regions, regions where the relative humidity with respect to ice (RHi) is greater than 100%. Small-scale dynamics have recently been shown to have a strong effect on the RHi of the UT/LS, and therefore on cirrus cloud formation. Until now, there has been insufficient data in the Tropical Tropopause Layer (TTL) to investigate these effects. The Airborne Tropical TRopopause EXperiment (ATTREX) was a series of campaigns focused on improving our understanding of humidity in the TTL. During this campaign, the NASA Langley/Ames Diode Laser Hygrometer was part of the payload on the NASA Global Hawk, resulting in measurements of humidity with as low as 1-2 m vertical resolution at altitudes up to 19 km. We will present observations from ATTREX describing the small scale spatial variability of water vapor along transects of ISSRs and cirrus clouds, as well as the dynamics driving the formation of ISS regions. These results will be discussed in context with results from prior UT/LS campaigns, such as DC3 and HIPPO.

  3. Small Scale Spatial Variability of Soil Properties and Nutrients in a Ferralsol under Corn

    NASA Astrophysics Data System (ADS)

    Alves, M. C.; Vidal Vázquez, E.; Pereira de Almeida, V.; Paz-Ferreiro, J.

    2012-04-01

    Spatial variability of soil attributes, both in natural and agricultural landscapes can be rather large. This heterogeneity results from interactions between pedogenetic processes and soil formation factors. In cultivated soils much variability can also occur as a result of land use and management effect, i.e. agricultural systems and practices. Therefore, the main objectives of this work were to investigate the statistical and geostatistical variability of selected properties in a soil cultivated with corn. The experimental work was carried out in Ilha Solteira, São Paulostate, Brazil and the soil was classified as an Oxisol (SSA), i.e. "Latossolo Vermelho" according to the Brazilian Soil Classification System. Eighty-four soil samples were collected at each of two different depths (0-10 and 10-20 cm) from the one-hectare plot studied. Sampling included a combination of grid and nesting schemes in order to allow description of the spatial variability at different scales. Soil texture fractions (sand, silt clay), organic matter content and pH (CaCl2) were determined using standard methods. Moreover, exchangeable bases (Ca, Mg, K), cation exchange capacity (CEC) and P were determined after exchange resin extraction. In the two depths studied, extractable P, K and Mg contents were found to be highly variable (C.V. > 30%), organic matter content and CEC showed a medium variability (C.V. ≈ 15-30%) and base percent saturation and pH exhibited a low variation (< 15%). Experimental semivariograms were computed and modeled and used to map the spatial variability of the study properties. Semivariograms provided a description of the pattern of spatial variability and some insight into possible process affecting the spatial distribution of the assessed soil properties. Sensitivity of nutrient spatial requirements to between field variability was discussed on the basis of the results obtained. In addition, the usefulness of kriging maps to improve and optimize productivity

  4. Quantifying spatial variability of indigenous nitrogen supply for precision nitrogen management in small scale farming

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Understanding spatial variability of indigenous nitrogen (N) supply (INS) is important to the implementation of precision nitrogen management strategies in intensive agricultural fields of North China Plain (NCP). The objectives of this study were to determine 1) winter wheat (Triticum aestivum L.) ...

  5. Statistical modeling of the small-scale spatial variability of snow depth

    NASA Astrophysics Data System (ADS)

    Grünewald, T.; Schirmer, M.; Lehning, M.

    2012-04-01

    The spatial distribution of the mountain snow cover is of high importance for many tasks in the fields of hydrology (e.g. water supply, flooding), natural hazards (e.g. snow avalanches) or mountain ecology. The snow distribution is typically characterized by a strong heterogeneity, which is the result of different processes interacting with the local topography. Characterizing this spatial heterogeneity is a challenging task. Recent studies showed that the prediction of the spatial structure of the snow cover applying simple terrain parameters has only minor explanatory power. Furthermore, most of these studies were limited either because they are restricted to a single region or due to a lack of snow depth data in reasonable quality and spatial resolution. For this study we were able to collect a large set of high resolution snow depth data from different regions in the Alps, the Pyrenees and the Rocky Mountains. The snow depth data were generated using airborne Lidar technology and have a horizontal resolution of 1 m and a vertical accuracy between 0.1 and 0.3 m. The size of the different domains is between 1 and 25 km2 and the data set cover different topographic and climatic regimes. We present a multivariate linear regression model which combines terrain variables such as elevation, slope and northing (deviation of the aspect from North) with the fractal roughness parameters D and γ in order to predict the relative snow depth of small subareas within the mountain catchments. Two methods were applied to select the subareas: on the one hand small control units were defined manually by clustering areas of similar surface characteristics. On the other hand the regions were automatically divided into quadratic subareas (400 m edge length). The model output is the relative snow amount for each subarea relative to the mean for the whole catchment. For each region the model was calculated separately and the best two-parameter model was chosen. In addition, combining

  6. Small-scale temporal and spatial variability in the erosion threshold and properties of cohesive intertidal sediments

    NASA Astrophysics Data System (ADS)

    Tolhurst, T. J.; Defew, E. C.; de Brouwer, J. F. C.; Wolfstein, K.; Stal, L. J.; Paterson, D. M.

    2006-03-01

    Intertidal mudflats can be highly patchy due to both biotic and abiotic variability. The problems caused by such patchiness for the measurement of the erosion threshold of sediments has only received limited attention, primarily because of the limitations of the devices used to measure erosion threshold. The cohesive strength meter (CSM) erosion device partly overcomes these problems because it can collect numerous measurements in a short time. This paper assesses the effects of site selection, small-scale spatial patchiness in a diatom biofilm and small-scale temporal variability over a tidal emersion on the measurement of erosion thresholds of cohesive intertidal sediments. Measurements were made with three CSM devices over a complete tidal emersion and at the beginning of the next emersion in the Westerschelde estuary, the Netherlands, in April 2001. Three different criteria were used in site selection: random sampling, random sampling with a user-bias towards visible diatom biofilms and sampling of only visible diatom biofilm areas. This resulted in different patterns of the measured sediment erodability. Contact core samples were collected to measure bio-dependant properties of the sediment known to influence erosion characteristics (water content and carbohydrates). In addition, variations in algal biomass ( F015) over time were measured at the sediment surface with a fluorescence monitoring system (FMS). Three different operational extractions of carbohydrates were analysed to assess the roles of different carbohydrates in stabilising the sediment (colloidal-S-, EDTA- extracted and ETOH-precipitated). Different responses in the erosion threshold to the tidal emersion were found depending upon the presence or absence of a diatom biofilm and on the sampling strategy used. Areas with a visible diatom biofilm showed a rapid increase in erosion threshold at the beginning of the emersion, whilst areas without a visible biofilm tended to show an increase at the end

  7. Small-scale temporal and spatial variability in the abundance of plastic pellets on sandy beaches: Methodological considerations for estimating the input of microplastics.

    PubMed

    Moreira, Fabiana Tavares; Prantoni, Alessandro Lívio; Martini, Bruno; de Abreu, Michelle Alves; Stoiev, Sérgio Biato; Turra, Alexander

    2016-01-15

    Microplastics such as pellets have been reported for many years on sandy beaches around the globe. Nevertheless, high variability is observed in their estimates and distribution patterns across the beach environment are still to be unravelled. Here, we investigate the small-scale temporal and spatial variability in the abundance of pellets in the intertidal zone of a sandy beach and evaluate factors that can increase the variability in data sets. The abundance of pellets was estimated during twelve consecutive tidal cycles, identifying the position of the high tide between cycles and sampling drift-lines across the intertidal zone. We demonstrate that beach dynamic processes such as the overlap of strandlines and artefacts of the methods can increase the small-scale variability. The results obtained are discussed in terms of the methodological considerations needed to understand the distribution of pellets in the beach environment, with special implications for studies focused on patterns of input. PMID:26677755

  8. Small-scale spatial variability of soil microbial community composition and functional diversity in a mixed forest

    NASA Astrophysics Data System (ADS)

    Wang, Qiufeng; Tian, Jing; Yu, Guirui

    2014-05-01

    Patterns in the spatial distribution of organisms provide important information about mechanisms that regulate the diversity and complexity of soil ecosystems. Therefore, information on spatial distribution of microbial community composition and functional diversity is urgently necessary. The spatial variability on a 26×36 m plot and vertical distribution (0-10 cm and 10-20 cm) of soil microbial community composition and functional diversity were studied in a natural broad-leaved Korean pine (Pinus koraiensis) mixed forest soil in Changbai Mountain. The phospholipid fatty acid (PLFA) pattern was used to characterize the soil microbial community composition and was compared with the community substrate utilization pattern using Biolog. Bacterial biomass dominated and showed higher variability than fungal biomass at all scales examined. The microbial biomass decreased with soil depths increased and showed less variability in lower 10-20 cm soil layer. The Shannon-Weaver index value for microbial functional diversity showed higher variability in upper 0-10 cm than lower 10-20 cm soil layer. Carbohydrates, carboxylic acids, polymers and amino acids are the main carbon sources possessing higher utilization efficiency or utilization intensity. At the same time, the four carbon source types contributed to the differentiation of soil microbial communities. This study suggests the higher diversity and complexity for this mix forest ecosystem. To determine the driving factors that affect this spatial variability of microorganism is the next step for our study.

  9. Empirical spatial econometric modelling of small scale neighbourhood

    NASA Astrophysics Data System (ADS)

    Gerkman, Linda

    2012-07-01

    The aim of the paper is to model small scale neighbourhood in a house price model by implementing the newest methodology in spatial econometrics. A common problem when modelling house prices is that in practice it is seldom possible to obtain all the desired variables. Especially variables capturing the small scale neighbourhood conditions are hard to find. If there are important explanatory variables missing from the model, the omitted variables are spatially autocorrelated and they are correlated with the explanatory variables included in the model, it can be shown that a spatial Durbin model is motivated. In the empirical application on new house price data from Helsinki in Finland, we find the motivation for a spatial Durbin model, we estimate the model and interpret the estimates for the summary measures of impacts. By the analysis we show that the model structure makes it possible to model and find small scale neighbourhood effects, when we know that they exist, but we are lacking proper variables to measure them.

  10. A geostatistical analysis of small-scale spatial variability in bacterial abundance and community structure in salt marsh creek bank sediments

    NASA Technical Reports Server (NTRS)

    Franklin, Rima B.; Blum, Linda K.; McComb, Alison C.; Mills, Aaron L.

    2002-01-01

    Small-scale variations in bacterial abundance and community structure were examined in salt marsh sediments from Virginia's eastern shore. Samples were collected at 5 cm intervals (horizontally) along a 50 cm elevation gradient, over a 215 cm horizontal transect. For each sample, bacterial abundance was determined using acridine orange direct counts and community structure was analyzed using randomly amplified polymorphic DNA fingerprinting of whole-community DNA extracts. A geostatistical analysis was used to determine the degree of spatial autocorrelation among the samples, for each variable and each direction (horizontal and vertical). The proportion of variance in bacterial abundance that could be accounted for by the spatial model was quite high (vertical: 60%, horizontal: 73%); significant autocorrelation was found among samples separated by 25 cm in the vertical direction and up to 115 cm horizontally. In contrast, most of the variability in community structure was not accounted for by simply considering the spatial separation of samples (vertical: 11%, horizontal: 22%), and must reflect variability from other parameters (e.g., variation at other spatial scales, experimental error, or environmental heterogeneity). Microbial community patch size based upon overall similarity in community structure varied between 17 cm (vertical) and 35 cm (horizontal). Overall, variability due to horizontal position (distance from the creek bank) was much smaller than that due to vertical position (elevation) for both community properties assayed. This suggests that processes more correlated with elevation (e.g., drainage and redox potential) vary at a smaller scale (therefore producing smaller patch sizes) than processes controlled by distance from the creek bank. c2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.

  11. Small-scale spatial variability of sperm and sei whales in relation to oceanographic and topographic features along the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Skov, H.; Gunnlaugsson, T.; Budgell, W. P.; Horne, J.; Nøttestad, L.; Olsen, E.; Søiland, H.; Víkingsson, G.; Waring, G.

    2008-01-01

    The 2004 Mid-Atlantic Ridge (MAR)-ECO expedition on the R.V. G.O. Sars provided the first opportunity to correlate oceanic distributions of cetaceans with synoptic acoustic (ADCP to 700 m depth, multi-beam echosounders) measurements of high-resolution, three-dimensional (3D) potential habitat (spatial scale<100 km). The identified habitat features were tested with independent observations from the Icelandic combined cetacean and redfish cruises in 2001 and 2003 using data from a 3D ocean general circulation model of the MAR region (Regional Oceans Modelling System (ROMS) model 5 km resolution). The spatial autocorrelation of sampled encounter rates of sperm Physeter macrocephalus and sei whales Balaenoptera borealis indicated scale-dependent variability in the distribution of both species. Despite the large area surveyed, the observations of both species exhibited a strong small-scale structure (range parameter 20-50 km), indicating affinities to cross-seamount or cross-frontal structures. Potential cross-seamount and cross-frontal habitat structures were derived from the acoustic transect data by analysing fine-scale gradients in the 3D flow patterns and bathymetry, including interactions between frontal and topographic parameters. PLS regression was used to determine the potential habitat drivers of sperm and sei whales, both during the G.O. Sars cruise and during the Icelandic cruises in 2001 and 2003. The selected parameters, which reflected flow gradients interacting with the steep topography, were finally applied for modelling the habitat suitability of both target species along the northern MAR using Ecological Niche Factor Analysis. The results suggest aggregations of sperm and sei whales along the MAR are primarily associated with fine-scale frontal processes interacting with the topography in the upper 100 m of the water column just north of the Sub-Polar Front (SPF) and the Charlie-Gibbs Fracture Zone (CGFZ). As moderate and high habitat suitabilities

  12. Spatial nonlocality of the small-scale solar dynamo

    SciTech Connect

    Lamb, D. A.; Howard, T. A.; DeForest, C. E.

    2014-06-10

    We explore the nature of the small-scale solar dynamo by tracking magnetic features. We investigate two previously explored categories of the small-scale solar dynamo: shallow and deep. Recent modeling work on the shallow dynamo has produced a number of scenarios for how a strong network concentration can influence the formation and polarity of nearby small-scale magnetic features. These scenarios have measurable signatures, for which we test using magnetograms from the Narrowband Filter Imager (NFI) on board Hinode. We find no statistical tendency for newly formed magnetic features to cluster around or away from network concentrations, nor do we find any statistical relationship between their polarities. We conclude that there is no shallow or 'surface' dynamo on the spatial scales observable by Hinode/NFI. In light of these results, we offer a scenario in which the subsurface field in a deep solar dynamo is stretched and distorted via turbulence, allowing the small-scale field to emerge at random locations on the photosphere.

  13. Small-Scale Variability of Large Cloud Drops

    NASA Technical Reports Server (NTRS)

    Marshak, Alexander; Knyazikhin, Y.; Wiscombe, Warren

    2004-01-01

    Cloud droplet size distribution is one of the most fundamental subjects in cloud physics. Understanding of spatial distribution and small-scale fluctuations of cloud droplets is essential for both cloud physics and atmospheric radiation. For cloud physics, it relates to the coalescence growth of raindrops while for radiation, it has a strong impact on a cloud's radiative properties. Most of the existing cloud radiation and precipitation formation models assume that the mean number of drops with a given radius varies proportionally to volume. The analysis of microphysical data on liquid water drop sizes shows that, for sufficiently small volumes, the number is proportional to the drop size dependent power of the volume. For abundant small drops present, the exponent is 1 as assumed in the conventional approach. However, for rarer large drops, the exponents fall below unity. At small scales, therefore, the mean number of large drops decreases with volume at a slower rate than the conventional approach assumes, suggesting more large drops at these scales than conventional models account for; their impact is consequently underestimated. Size dependent models of spatial distribution of cloud drops that simulate the observed power laws show strong drop clustering, the more so the larger the drops. The degree of clustering is determined by the observed exponents. The strong clustering of large drops arises naturally from the observed power-law statistics. Current theories of photon-cloud interaction and warm rain formation will need radical revision in order to produce these statistics; their underlying equations are unable to yield the observed power law.

  14. Statistical maps of small-scale electric field variability in the high-latitude ionosphere

    NASA Astrophysics Data System (ADS)

    Cousins, E. D. P.; Shepherd, S. G.

    2012-12-01

    Statistical maps of small-scale electric field variability in the high-latitude ionosphere are derived for the Northern and Southern Hemispheres using 48 months of data from the Super Dual Auroral Radar Network (SuperDARN). Maps of variability magnitude (from scales of 45-450 km and 2-20 min) are derived for a range of interplanetary magnetic field (IMF) orientations and dipole tilt angles (the angle between the best fit dipole axis and the plane perpendicular to the Sun-Earth line). It is found that the observed spatial distribution of average variability is significantly modified as the IMF and dipole tilt conditions change. Under negative (winter-like) and neutral (equinox-like) dipole tilt angles, variability is concentrated in the auroral and dayside cusp regions, and the spatial distributions of variability appear to be correlated to those of large- and small-scale field-aligned currents (FACs). Additionally, variability on the nightside is found to be more enhanced in the downward FAC region than it is in the upward FAC region. Under positive (summer-like) dipole tilt angles, the average variability magnitudes across the high-latitude regions are smaller than those observed under negative dipole tilt angles, and the spatial distributions are more uniform. These dipole tilt effects suggest that scale-size- and conductivity-dependent field-aligned potential drops and conductivity-dependent changes in the processes that generate variability are possible factors that impact the observed small-scale electric field variability. In general, Southern Hemisphere maps appear very similar to Northern Hemisphere maps, although some minor differences are observed that may result from interhemispheric asymmetries in the geomagnetic field.

  15. Small scale variability of snow properties on Antarctic sea ice

    NASA Astrophysics Data System (ADS)

    Wever, Nander; Leonard, Katherine; Paul, Stephan; Jacobi, Hans-Werner; Proksch, Martin; Lehning, Michael

    2016-04-01

    Snow on sea ice plays an important role in air-ice-sea interactions, as snow accumulation may for example increase the albedo. Snow is also able to smooth the ice surface, thereby reducing the surface roughness, while at the same time it may generate new roughness elements by interactions with the wind. Snow density is a key property in many processes, for example by influencing the thermal conductivity of the snow layer, radiative transfer inside the snow as well as the effects of aerodynamic forcing on the snowpack. By comparing snow density and grain size from snow pits and snow micro penetrometer (SMP) measurements, highly resolved density and grain size profiles were acquired during two subsequent cruises of the RV Polarstern in the Weddell Sea, Antarctica, between June and October 2013. During the first cruise, SMP measurements were done along two approximately 40 m transects with a horizontal resolution of approximately 30 cm. During the second cruise, one transect was made with approximately 7.5 m resolution over a distance of 500 m. Average snow densities are about 300 kg/m3, but the analysis also reveals a high spatial variability in snow density on sea ice in both horizontal and vertical direction, ranging from roughly 180 to 360 kg/m3. This variability is expressed by coherent snow structures over several meters. On the first cruise, the measurements were accompanied by terrestrial laser scanning (TLS) on an area of 50x50 m2. The comparison with the TLS data indicates that the spatial variability is exhibiting similar spatial patterns as deviations in surface topology. This suggests a strong influence from surface processes, for example wind, on the temporal development of density or grain size profiles. The fundamental relationship between variations in snow properties, surface roughness and changes therein as investigated in this study is interpreted with respect to large-scale ice movement and the mass balance.

  16. Small-scale variability of alpine snow packs from fiber-optic distributed temperature

    NASA Astrophysics Data System (ADS)

    Huwald, H.; Williams, S.; Higgins, C. W.; Nolin, A. W.; Drake, S. A.; Selker, J. S.; Parlange, M. B.

    2012-04-01

    Variations in small-scale surface roughness, snow density and in the snowpack microstructure influence the surface and internal snow temperature, being key quantities for various heat flux components of the surface energy balance. Detailed knowledge on the spatial distribution and temporal evolution of snow temperature is crucial to quantify spatial variability in the subsurface and surface heat fluxes of the snow pack. We present measurements of small-scale temperature variations in alpine snow packs using fiber-optic distributed temperature sensing (DTS) together with traditional sensors at spatial resolutions much smaller than most common distributed snow cover models to shed light on subgrid-scale physics. Fiber-optic cables of several 100m were installed in a fence-like configuration in in the Swiss Alps to obtain 2D information on subgrid-scale snow variability. The setup allowed for computation of subsurface heat fluxes at 1m spatial resolution along the measurement transect based on the Fourier heat equation using snow temperature and snow depth data, and an effective thermal conductivity of the snow derived from density measurements.

  17. Small-scale spatial variations of shortwave downward radiation

    NASA Astrophysics Data System (ADS)

    Becker, Ralf; Gebauer, Petra; Behrens, Klaus

    2013-05-01

    DWD/Meteorological Observatory Lindenberg is operating a small-scale ground-based network of measurement sites for precipitation and shortwave radiation. The area is located roughly 60 km southeast of Berlin city. 8 measurement sites are equipped with high quality instruments CM21/CM11 by Kipp & Zonen. The quality assessment routinely applied takes into account the basic astronomical and empirical considerations as well as some interdependencies like total to diffuse flux ratio and cross checking with sunshine duration. Possible shading due to growing vegetation is taken into account, too. This is complemented by an approach that is utilizing time-series of clear sky radiative transfer simulations for every site. For that purpose a link to cloud coverage obtained from Meteosat second generation geostationary satellite data, highly resolved in time and space, was established. The paper provides an overview of the surface radiation network and the current activities to improve automatic quality assessment using remotely sensed data and clear sky modelling. First evaluation efforts cover up to 12 years of data.

  18. Small-scale spatial structuring of interstitial invertebrates on three embayed beaches, Sydney, Australia

    NASA Astrophysics Data System (ADS)

    Cooke, Belinda C.; Goodwin, Ian D.; Bishop, Melanie J.

    2014-10-01

    An understanding of ecological processes hinges upon an understanding of the spatial structuring of their key biotic components. Interstitial invertebrates are a ubiquitous and ecologically important component of sandy beach ecosystems. As many sandy beach taxa have limited dispersal, it may be expected that their populations exhibit a high degree of spatial structuring, yet the spatial scales across which they display baseline variability remain largely unknown. To assess (1) whether interstitial invertebrates display patchiness on embayed sandy beaches, (2) whether the size of patches they form is consistent across three geographically proximal beaches, (3) the key environmental correlates of this variation and (4) its taxonomic dependence, samples were collected at regular (0.5 m) intervals along 15 m long geomorphically similar stretches of three proximal intermediate beaches and analyses of spatial autocorrelation were conducted. On each of the three beaches, interstitial invertebrate communities formed patches of 2-4.5 m in diameter. Spatial structuring of invertebrate communities was driven by harpacticoid copepods and gastrotrichs, and corresponded to spatial structuring of sediments. Sediments, however, explained only 33% of spatial variation in faunal communities, indicating the importance of other abiotic and/or biotic factors. Our study highlights that even on seemingly homogeneous sandy beaches, faunal communities may display considerable small-scale spatial structuring. Examination of spatial structure may lead to a greater understanding of the ecological processes in this system.

  19. Plant community assembly at small scales: Spatial vs. environmental factors in a European grassland

    NASA Astrophysics Data System (ADS)

    Horn, Sebastian; Hempel, Stefan; Ristow, Michael; Rillig, Matthias C.; Kowarik, Ingo; Caruso, Tancredi

    2015-02-01

    Dispersal limitation and environmental conditions are crucial drivers of plant species distribution and establishment. As these factors operate at different spatial scales, we asked: Do the environmental factors known to determine community assembly at broad scales operate at fine scales (few meters)? How much do these factors account for community variation at fine scales? In which way do biotic and abiotic interactions drive changes in species composition? We surveyed the plant community within a dry grassland along a very steep gradient of soil characteristics like pH and nutrients. We used a spatially explicit sampling design, based on three replicated macroplots of 15 × 15, 12 × 12 and 12 × 12 m in extent. Soil samples were taken to quantify several soil properties (carbon, nitrogen, plant available phosphorus, pH, water content and dehydrogenase activity as a proxy for overall microbial activity). We performed variance partitioning to assess the effect of these variables on plant composition and statistically controlled for spatial autocorrelation via eigenvector mapping. We also applied null model analysis to test for non-random patterns in species co-occurrence using randomization schemes that account for patterns expected under species interactions. At a fine spatial scale, environmental factors explained 18% of variation when controlling for spatial autocorrelation in the distribution of plant species, whereas purely spatial processes accounted for 14% variation. Null model analysis showed that species spatially segregated in a non-random way and these spatial patterns could be due to a combination of environmental filtering and biotic interactions. Our grassland study suggests that environmental factors found to be directly relevant in broad scale studies are present also at small scales, but are supplemented by spatial processes and more direct interactions like competition.

  20. Small-Scale Spatial Variation in Population Dynamics and Fishermen Response in a Coastal Marine Fishery

    PubMed Central

    Wilson, Jono R.; Kay, Matthew C.; Colgate, John; Qi, Roy; Lenihan, Hunter S.

    2012-01-01

    A major challenge for small-scale fisheries management is high spatial variability in the demography and life history characteristics of target species. Implementation of local management actions that can reduce overfishing and maximize yields requires quantifying ecological heterogeneity at small spatial scales and is therefore limited by available resources and data. Collaborative fisheries research (CFR) is an effective means to collect essential fishery information at local scales, and to develop the social, technical, and logistical framework for fisheries management innovation. We used a CFR approach with fishing partners to collect and analyze geographically precise demographic information for grass rockfish (Sebastes rastrelliger), a sedentary, nearshore species harvested in the live fish fishery on the West Coast of the USA. Data were used to estimate geographically distinct growth rates, ages, mortality, and length frequency distributions in two environmental subregions of the Santa Barbara Channel, CA, USA. Results indicated the existence of two subpopulations; one located in the relatively cold, high productivity western Channel, and another in the relatively warm, low productivity eastern Channel. We parameterized yield per recruit models, the results of which suggested nearly twice as much yield per recruit in the high productivity subregion relative to the low productivity subregion. The spatial distribution of fishing in the two environmental subregions demonstrated a similar pattern to the yield per recruit outputs with greater landings, effort, and catch per unit effort in the high productivity subregion relative to the low productivity subregion. Understanding how spatial variability in stock dynamics translates to variability in fishery yield and distribution of effort is important to developing management plans that maximize fishing opportunities and conservation benefits at local scales. PMID:23300793

  1. Analysis of small scale turbulent structures and the effect of spatial scales on gas transfer

    NASA Astrophysics Data System (ADS)

    Schnieders, Jana; Garbe, Christoph

    2014-05-01

    The exchange of gases through the air-sea interface strongly depends on environmental conditions such as wind stress and waves which in turn generate near surface turbulence. Near surface turbulence is a main driver of surface divergence which has been shown to cause highly variable transfer rates on relatively small spatial scales. Due to the cool skin of the ocean, heat can be used as a tracer to detect areas of surface convergence and thus gather information about size and intensity of a turbulent process. We use infrared imagery to visualize near surface aqueous turbulence and determine the impact of turbulent scales on exchange rates. Through the high temporal and spatial resolution of these types of measurements spatial scales as well as surface dynamics can be captured. The surface heat pattern is formed by distinct structures on two scales - small-scale short lived structures termed fish scales and larger scale cold streaks that are consistent with the footprints of Langmuir Circulations. There are two key characteristics of the observed surface heat patterns: 1. The surface heat patterns show characteristic features of scales. 2. The structure of these patterns change with increasing wind stress and surface conditions. In [2] turbulent cell sizes have been shown to systematically decrease with increasing wind speed until a saturation at u* = 0.7 cm/s is reached. Results suggest a saturation in the tangential stress. Similar behaviour has been observed by [1] for gas transfer measurements at higher wind speeds. In this contribution a new model to estimate the heat flux is applied which is based on the measured turbulent cell size und surface velocities. This approach allows the direct comparison of the net effect on heat flux of eddies of different sizes and a comparison to gas transfer measurements. Linking transport models with thermographic measurements, transfer velocities can be computed. In this contribution, we will quantify the effect of small scale

  2. Retrievals on Tropical small scale humidity variability from multi-channel microwave radiometer

    NASA Astrophysics Data System (ADS)

    Zhang, Jianhao; Zuidema, Paquita; Turner, David

    2016-04-01

    Small-scale atmospheric humidity structure is important to many atmospheric process studies. In the Tropics especially, convection is sensitive to small variations in humidity. High temporal-resolution humidity profiles and spatially-resolved humidity fields are valuable for understanding the relationship of convection to tropical humidity, such as at convectively-induced cold pools and as part of the shallow-to-deep cloud transition. Radiosondes can provide high resolution vertical profiles of temperature and humidity, but are relatively infrequent. Microwave radiometers (MWR) are able to profile and scan autonomously and output measurements frequently (~1 Hz). To date, few assessments of microwave humidity profiling in the Tropics have been undertaken. Löhnert et al. (2009) provide one evaluation for Darwin, Australia. We build on this using four months of data from the equatorial Indian Ocean, at Gan Island, collected from University of Miami's (UM) multi-channel radiometer during the Dynamics of Madden-Julian Oscillation (DYNAMO) field campaign. Liquid Water Path (LWP) and Water Vapor Path (WVP) are physically retrieved using the MWR RETrieval (MWRRET) algorithm (Turner et al., 2007b), and humidity profiles in the tropics are retrieved using the Integrated Profiling Technique (Löhnert et al., 2004). Tropical temperature variability is weak and a climatological temperature profile is assumed, with humidity information drawn from five channels between 22 to 30 GHz. Scanning measurements were coordinated with the scanning pattern of NCAR's S-Pol-Ka radar. An analysis of the humidity information content gathered from both the profiling and scanning measurements will be presented.

  3. Influence of small scale rainfall variability on standard comparison tools between radar and rain gauge data

    NASA Astrophysics Data System (ADS)

    Gires, Auguste; Tchiguirinskaia, Ioulia; Schertzer, Daniel; Schellart, Alma; Berne, Alexis; Lovejoy, Shaun

    2014-03-01

    Rain gauges and weather radars do not measure rainfall at the same scale; roughly 20 cm for the former and 1 km for the latter. This significant scale gap is not taken into account by standard comparison tools (e.g. cumulative depth curves, normalized bias, RMSE) despite the fact that rainfall is recognized to exhibit extreme variability at all scales. In this paper we suggest to revisit the debate of the representativeness of point measurement by explicitly modelling small scale rainfall variability with the help of Universal Multifractals. First the downscaling process is validated with the help of a dense networks of 16 disdrometers (in Lausanne, Switzerland), and one of 16 rain gauges (Bradford, United Kingdom) both located within a 1 km2 area. Second this downscaling process is used to evaluate the impact of small scale (i.e. sub-radar pixel) rainfall variability on the standard indicators. This is done with rainfall data from the Seine-Saint-Denis County (France). Although not explaining all the observed differences, it appears that this impact is significant which suggests changing some usual practice.

  4. Driving factors of small-scale variability in a savanna plant population after a fire

    NASA Astrophysics Data System (ADS)

    Dodonov, Pavel; Xavier, Rafael de Oliveira; Tiberio, Fernanda Cristina dos Santos; Lucena, Isabela Codolo de; Zanelli, Carolina Brandão; Silva Matos, Dalva Maria da

    2014-04-01

    The severity of fire impacts on fire-prone vegetation is often spatially heterogeneous, and may lead to small-scale patchiness in the structure of plant populations by affecting mortality, topkill, and reproduction. This patchiness, however, is not usually taken into account in fire ecology studies. We show that a dry-season fire may result in small-scale patchiness in the population structure of the common shrub Miconia albicans, mostly by differential topkill and resprouting. We related fire severity to population structure parameters of the study species and assessed the effects of fire on its soil seed bank. Basal area of non-woody live stems and of dead stems increased with fire severity, whereas that of woody live stems decreased, indicating topkill and resprouting. However, there was no relationship between fire severity and the total number of live or dead plants, showing that mortality in the fire was low. We found very few seedlings, indicating that resprouting, not germination from the soil seed bank, is the main recovery strategy of this species. The fire also affected the soil seed bank, as there were fewer seedlings emerging from soil collected in burned patches. Although this study was performed with a single species, it is likely that other species, especially those with basal resprouting, will show similar patterns of post-fire patchiness in population structure. This patchiness, in turn, may affect the spatial distribution of future fires, and should be taken into account in studies of fire ecology.

  5. Spatially resolved sub-Doppler overtone gain measurements on a small-scale supersonic HF laser

    NASA Astrophysics Data System (ADS)

    Wisniewski, Charles F.; Hewett, Kevin B.; Manke, Gerald C., II; Truman, C. Randall; Hager, Gordon D.

    2004-05-01

    The small signal gain of a small-scale HF overtone laser was measured using a sub-Doppler tunable diode laser system. Measurements of reactant concentration, flow velocity and gain length were also made. The spatially resolved, two-dimensional small signal gain and temperature maps that were generated show a highly inhomogeneous gain medium indicating the dominant role played by mixing of the H2 and F streams in HF laser performance. The measured gain and temperature data were analyzed with the aid of a two-dimensional computational fluid dynamics model. The results show that reactant mixing mechanisms have a large effect on the gain averaged over a vertical profile while kinetic rate mechanisms, including reaction rate constants and reactant concentration, have a greater effect on the maximum system gain.

  6. Assessment of small-scale integrated water vapour variability during HOPE

    NASA Astrophysics Data System (ADS)

    Steinke, S.; Eikenberg, S.; Löhnert, U.; Dick, G.; Klocke, D.; Di Girolamo, P.; Crewell, S.

    2014-09-01

    The spatio-temporal variability of integrated water vapour (IWV) on small-scales of less than 10 km and hours is assessed with data from the two months of the High Definition Clouds and Precipitation for advancing Climate Prediction (HD(CP)2) Observational Prototype Experiment (HOPE). The statistical intercomparison of the unique set of observations during HOPE (microwave radiometer (MWR), Global Positioning System (GPS), sunphotometer, radiosondes, Raman Lidar, infrared and near infrared Moderate Resolution Imaging Spectroradiometer (MODIS) on the satellites Aqua and Terra) measuring close together reveals a good agreement in terms of standard deviation (≤ 1 kg m-2) and correlation coefficient (≥ 0.98). The exception is MODIS, which appears to suffer from insufficient cloud filtering. For a case study during HOPE featuring a typical boundary layer development, the IWV variability in time and space on scales of less than 10 km and less than 1 h is investigated in detail. For this purpose, the measurements are complemented by simulations with the novel ICOsahedral Non-hydrostatic modelling framework (ICON) which for this study has a horizontal resolution of 156 m. These runs show that differences in space of 3-4 km or time of 10-15 min induce IWV variabilities in the order of 4 kg m-2. This model finding is confirmed by observed time series from two MWRs approximately 3 km apart with a comparable temporal resolution of a few seconds. Standard deviations of IWV derived from MWR measurements reveal a high variability (> 1 kg m-2) even at very short time scales of a few minutes. These cannot be captured by the temporally lower resolved instruments and by operational numerical weather prediction models such as COSMO-DE (an application of the Consortium for Small-scale Modelling covering Germany) of Deutscher Wetterdienst, which is included in the comparison. However, for time scales larger than 1 h, a sampling resolution of 15 min is sufficient to capture the

  7. Assessment of small-scale integrated water vapour variability during HOPE

    NASA Astrophysics Data System (ADS)

    Steinke, S.; Eikenberg, S.; Löhnert, U.; Dick, G.; Klocke, D.; Di Girolamo, P.; Crewell, S.

    2015-03-01

    The spatio-temporal variability of integrated water vapour (IWV) on small scales of less than 10 km and hours is assessed with data from the 2 months of the High Definition Clouds and Precipitation for advancing Climate Prediction (HD(CP)2) Observational Prototype Experiment (HOPE). The statistical intercomparison of the unique set of observations during HOPE (microwave radiometer (MWR), Global Positioning System (GPS), sun photometer, radiosondes, Raman lidar, infrared and near-infrared Moderate Resolution Imaging Spectroradiometer (MODIS) on the satellites Aqua and Terra) measuring close together reveals a good agreement in terms of random differences (standard deviation ≤1 kg m-2) and correlation coefficient (≥ 0.98). The exception is MODIS, which appears to suffer from insufficient cloud filtering. For a case study during HOPE featuring a typical boundary layer development, the IWV variability in time and space on scales of less than 10 km and less than 1 h is investigated in detail. For this purpose, the measurements are complemented by simulations with the novel ICOsahedral Nonhydrostatic modelling framework (ICON), which for this study has a horizontal resolution of 156 m. These runs show that differences in space of 3-4 km or time of 10-15 min induce IWV variabilities on the order of 0.4 kg m-2. This model finding is confirmed by observed time series from two MWRs approximately 3 km apart with a comparable temporal resolution of a few seconds. Standard deviations of IWV derived from MWR measurements reveal a high variability (> 1 kg m-2) even at very short time scales of a few minutes. These cannot be captured by the temporally lower-resolved instruments and by operational numerical weather prediction models such as COSMO-DE (an application of the Consortium for Small-scale Modelling covering Germany) of Deutscher Wetterdienst, which is included in the comparison. However, for time scales larger than 1 h, a sampling resolution of 15 min is

  8. Direct Numerical Simulations of Small-Scale Gravity Wave Instability Dynamics in Variable Stratification and Shear

    NASA Astrophysics Data System (ADS)

    Mixa, T.; Fritts, D. C.; Laughman, B.; Wang, L.; Kantha, L. H.

    2015-12-01

    Multiple observations provide compelling evidence that gravity wave dissipation events often occur in multi-scale environments having highly-structured wind and stability profiles extending from the stable boundary layer into the mesosphere and lower thermosphere. Such events tend to be highly localized and thus yield local energy and momentum deposition and efficient secondary gravity wave generation expected to have strong influences at higher altitudes [e.g., Fritts et al., 2013; Baumgarten and Fritts, 2014]. Lidars, radars, and airglow imagers typically cannot achieve the spatial resolution needed to fully quantify these small-scale instability dynamics. Hence, we employ high-resolution modeling to explore these dynamics in representative environments. Specifically, we describe numerical studies of gravity wave packets impinging on a sheet of high stratification and shear and the resulting instabilities and impacts on the gravity wave amplitude and momentum flux for various flow and gravity wave parameters. References: Baumgarten, Gerd, and David C. Fritts (2014). Quantifying Kelvin-Helmholtz instability dynamics observed in noctilucent clouds: 1. Methods and observations. Journal of Geophysical Research: Atmospheres, 119.15, 9324-9337. Fritts, D. C., Wang, L., & Werne, J. A. (2013). Gravity wave-fine structure interactions. Part I: Influences of fine structure form and orientation on flow evolution and instability. Journal of the Atmospheric Sciences, 70(12), 3710-3734.

  9. Combination of snowpack modelling and TLS observations to analyze small scale spatial varaiability of snowpack energy and mass balance

    NASA Astrophysics Data System (ADS)

    Revuelto, Jesús; Vionnet, Vincent; López-Moreno, Juan Ignacio; Lafaysse, Matthieu; Morin, Samuel

    2015-04-01

    Improving the comprehension on how the different energetic balance components affect the snowpack mass balance during the melting period is important from a hydrological point of view. An accurate Snow Water Equivalent (SWE) distribution is needed for this objective, but unfortunately SWE measurement over large areas is not feasible nowadays. This distribution can be provided by a snowpack model but simulations often differ from the real state, because some physical processes are not yet properly modelled. In this study, we take advantage of distributed snowpack simulations corrected throughout the snow season with several snow depth distributions measured with a Terrestrial Laser Scanner (TLS). This allows us to obtain a more realistic SWE evolution and analyse its relations with the snowpack surface energy balance during the melting period considering small scale spatial variability. For 2012, 2013 and 2014 snow seasons several intensive TLS snow depth data acquisitions were accomplished at Izas Experimental catchment; a 52ha study site located in central Spanish Pyrenees with an elevation that ranges between 2050 to 2350m above sea level. The detailed snowpack model Crocus has been used for simulating the snowpack evolution at 5m grid spacing during these three snow seasons, driven by downscaled meteorological fields from the SAFRAN reanalysis. Shadow effects on direct solar radiation are explicitly considered in the snowpack simulation. When a snow depth distribution map measured with the TLS was available, the simulation was stopped and the modelled snow depth distribution was adjusted to match observations. Afterwards the snow simulation was restarted, being subsequently simulated a more realistic snowpack distribution. Considering this improved simulation, the components of the surface energy balance simulated by Crocus were analysed in relation to the simulated mass balance dynamics during the melting period. In such a way a Principal Component Analysis

  10. Spatial clustering of Diabrotica virgifera virgifera and Agriotes ustulatus in small-scale maize fields without topographic relief drift

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The soil living larvae of Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) and Agriotes ustulatus Schaller (Elateridae) can cause economic damage to maize roots. This study investigated the spatial clustering of both pests in four small-scale maize fields in southern Hungary, wher...

  11. Small-scale spatial distribution and oogenetic synchrony in brittlestars (Echinodermata: Ophiuroidea)

    NASA Astrophysics Data System (ADS)

    Doyle, Gina M.; Hamel, Jean-François; Mercier, Annie

    2014-01-01

    There is increasing evidence that spatial factors modulate reproductive processes over large (>150 km) and medium (10-100 km) scales in marine taxa, but few studies have explicitly determined the degree of inter-individual synchrony in gamete development at smaller scales within benthic populations. Using a ubiquitous broadcast-spawning species, the brittlestar Ophiopholis aculeata, we assessed variations in gametogenic activity over the annual reproductive cycle at various scales. Quantitative indices of oogenic maturity were compared in females collected: (1) in two substrata at a given site (distant ˜200-300 m), (2) among clusters of individuals living in relatively close proximity (˜10-50 m), and (3) within each cluster of individuals collected under/inside a given substratum (˜2-20 cm). Gametogenic maturity was also examined in females collected from distant sites (˜50-150 km). At the main study site, oogenic cohesion was greater within and among clusters of a given substratum than between substrata, and differences in reproductive output and spawning periods occurred between individuals from the two substrata studied. At the finest scale (within clusters of individuals) oogenic synchrony was maximal just before spawning. Comparing samples from distant geographic locations (>50 km) showed significant asynchrony outside the pre-spawning period. The present study shows that relatively high levels of asynchrony in gamete maturation may exist among conspecifics of a seemingly homogeneous population, except at the closest scale (within clusters) at the culmination of the reproductive cycle (near spawning). This emphasizes the likely interplay of inter-individual exchanges and small-scale distribution on the fine coordination of reproductive events.

  12. Two-dimensional small-scale variability of pore water phosphate in freshwater lakes: results from a novel dialysis sampler.

    PubMed

    Lewandowski, Jorg; Rüter, Kristina; Hupfer, Michael

    2002-05-01

    Vertical concentration profiles of soluble reactive phosphorus (SRP) in the upper sedimentary zone of freshwater lakes are an important means for studying internal phosphorus (P) loading and to gain insight into early diagenetic processes. The interpretation of such pore water profiles generally neglects the occurrence of horizontal variability at a specific sampling site. To further examine this variability, we have designed a novel two-dimensional sampler (2D peeper) consisting of 2280 chambers at a spatial resolution of 9 mm providing a sampling area of 43 x 44 cm. This new device was deployed in three eutrophic lakes in north-eastern Germany. The resulting 2D images of the SRP concentrations, diffusive fluxes, and turnover rates revealed systematic vertical and horizontal structures with local niches of increased phosphorus release. Thus, the extrapolation of P flux calculations based on one-dimensional pore water profiles may lead to a considerable error. The observed small-scale horizontal heterogeneity, probably mainly caused by organisms, was larger in the biologically more active Lake Müllrose and Süsser See than in the deeper Arendsee where meio- and macrozoobenthos were missing. In all cases, the variability was highest at the sediment-water interface and diminished with sediment depth. PMID:12026990

  13. Impacts of small-scale variability on the determination of bulk thermal diffusivity in snowpacks

    NASA Astrophysics Data System (ADS)

    Oldroyd, H. J.; Higgins, C. W.; Huwald, H.; Selker, J. S.; Parlange, M. B.

    2012-04-01

    Thermal diffusivity of snow is an important physical property associated with key hydrological phenomena such as snowmelt and heat and water vapor exchange with the atmosphere. These phenomena have broad implications in studies of climate and heat and water budgets on many scales. Furthermore, sub grid scale phenomena may enhance these heat and mass exchanges in the snow pack due to its porous nature. We hypothesize that the heat transfer effects of these small-scale variabilities may be seen as an increased bulk thermal diffusivity of the snow. Direct measurements of snow thermal diffusivity require coupled measurements of thermal conductivity and density, which are nonstationary due to snow metamorphism. Furthermore, thermal conductivity measurements are typically obtained with specialized heating probes or plates and snow density measurements require digging snow pits. Therefore, direct measurements are difficult to obtain with high enough temporal resolution such that direct comparisons with atmospheric conditions can be made. This study uses highly resolved temperature measurements from the Plaine Morte glacier in Switzerland as initial and boundary conditions to numerically solve the 1D heat equation and iteratively optimize for thermal diffusivity. The method uses flux boundary conditions to constrain thermal diffusivity such that spuriously high values in thermal diffusivity are eliminated. Additionally, a t-test ensuring statistical significance between solutions of varied thermal diffusivity results in further constraints on thermal diffusivity that eliminate spuriously low values. The results show that time resolved thermal diffusivity can be determined from easily implemented and inexpensive temperature measurements of seasonal snow with good agreement to widely used parameterizations based on snow density. This high time resolution further affords the ability to explore possible turbulence-induced enhancements to heat and mass transfer in the snow.

  14. The effect of small scale variablity in isotopic composition of precipitation on hydrograph separation results

    NASA Astrophysics Data System (ADS)

    Fischer, Benjamin; van Meerveld, Ilja; Seibert, Jan

    2016-04-01

    Understanding runoff processes is important for predictions of streamflow quantity and quality. The two-component isotope hydrograph separation (IHS) method is a valuable tool to study how catchments transform rainfall into runoff. IHS allows the stormflow hydrograph to be separated into rainfall (event water) and water that was stored in the catchment before the event (pre-event water). To be able to perform an IHS, water samples of baseflow (pre-event water) and stormflow are collected at the stream outlet. Rainfall is usually collected at one location by hand as an event total or sampled sequentially during the event. It is usually assumed that the spatial variability in rainfall and the isotopic composition of rainfall are negligible for small (<10km2) catchments. However, different studies have shown that precipitation can vary within short distances. Subsequently it remains unclear how the spatio-temproal variability of rainfall and the stable isotope composition of rainfall affect the results of an IHS. In this study, we investigated the effects of the spatio-temporal variability in the isotopic composition of rainfall across a small headwater catchment in Switzerland. Rainfall was measured at eight locations and three streams (catchment area of 0.15, 0.23, and 0.7 km2). The isotopic composition of rainfall and streamflow were sampled for 10 different rain events (P: 5 mm intervals, Q: 12 to 51 samples per events). This dataset was used to perform a two-component isotope hydrograph separation. The results show that for some events the spatial variability in total rainfall, mean and maximum rainfall intensity and stable isotope composition of rainfall was high. There was no relation between the stable isotope composition of rainfall and the rainfall sum, rainfall intensity or altitude. The spatial variability of the isotopic composition of rainfall was for 4 out of the 10 events as large as the temporal variability in the isotopic composition. Different

  15. From Snow Depth Distribution to Small-Scale Variability of Soil Temperatures

    NASA Astrophysics Data System (ADS)

    Gisnås, Kjersti; Westermann, Sebastian; Etzelmüller, Bernd; Schuler, Thomas V.

    2013-04-01

    Permafrost is a temperature phenomenon on the local scale. Soil temperatures are not only influenced by atmospheric conditions varying on scales of kilometers, but are also determined by the land cover and soil properties, which display large variability on the meter-scale in many permafrost areas. In mountain areas the seasonal snow cover is crucial for the ground thermal regime, and the redistribution of snow by wind can create a pattern of different snow depths, which results in spatially variable permafrost temperatures. Existing permafrost models (CryoGRID1.0 and CryoGRID2.0) are implemented at 1x1km spatial resolution for Norway, and have proven to capture the regional distribution of permafrost. One of the principal uncertainties of these models is the effect of sub-grid variability in snow cover, and downscaling approaches for snow are therefore required to get a satisfactorily representation of the ground thermal regime. An extensive dataset including ground temperatures of 7 boreholes and data of 5 stations measuring snow depth and air/ground surface temperature is available from Juvflye, a high-mountain site in central southern Norway (1800-1900m a.s.l.). The area has a rough topography and a seasonal snow cover dominated by heavy wind redistribution. A Ground Penetration Radar (GPR) survey of snow depth was conducted in March 2012, covering an 8km2 area including the 7 boreholes. This GPR-survey will be repeated in 2013. The measured snow depths form the basis for probability density functions (PDFs) of snow cover within each 1x1km grid cell for this area. A 1-D numerical model including both a soil thermal model and snow pack scheme are calibrated for all 7 boreholes. Several model runs are performed for different snow depths, intended to cover the range of observed values. We present the effects of different snow depths on the thermal regime of the underlying permafrost, based on this model attempt. Furthermore, we outline a probabilistic approach for

  16. Mercury Exposure Assessment and Spatial Distribution in A Ghanaian Small-Scale Gold Mining Community.

    PubMed

    Rajaee, Mozhgon; Long, Rachel N; Renne, Elisha P; Basu, Niladri

    2015-09-01

    Mercury is utilized worldwide in artisanal and small-scale gold mining (ASGM) and may pose a risk for miners and mining communities. While a number of studies have characterized mercury in ASGM communities, most have focused on a single media and few have taken a holistic approach. Here, a multiple media exposure assessment and cross-sectional study of mercury was conducted in 2010 through 2012 in northeast Ghana with a small-scale gold mining community, Kejetia, a subsistence farming community, Gorogo, and an urban ASGM gold refinery in Bolgatanga. The objective was to assess mercury in a range of human (urine and hair) and ecological (household soil, sediment, fish, and ore) samples to increase understanding of mercury exposure pathways. All participants were interviewed on demographics, occupational and medical histories, and household characteristics. Participants included 90 women of childbearing age and 97 adults from Kejetia and 75 adults from Gorogo. Median total specific gravity-adjusted urinary, hair, and household soil mercury were significantly higher in Kejetia miners (5.18 µg/L, 0.967 µg/g, and 3.77 µg/g, respectively) than Kejetia non-miners (1.18 µg/L, 0.419 µg/g, and 2.00 µg/g, respectively) and Gorogo participants (0.154 µg/L, 0.181 µg/g, and 0.039 µg/g) in 2011. Sediment, fish, and ore Hg concentrations were below guideline values. Median soil mercury from the Bolgatanga refinery was very high (54.6 µg/g). Estimated mean mercury ingestion for Kejetia adults from soil and dust exceeded the U.S. Environmental Protection Agency reference dose (0.3 µg Hg/kg·day) for pica (0.409 µg Hg/kg·day) and geophagy (20.5 µg Hg/kg·day) scenarios. Most participants with elevated urinary and household soil mercury were miners, but some non-miners approached and exceeded guideline values, suggesting a health risk for non-mining residents living within these communities. PMID:26340636

  17. Mercury Exposure Assessment and Spatial Distribution in A Ghanaian Small-Scale Gold Mining Community

    PubMed Central

    Rajaee, Mozhgon; Long, Rachel N.; Renne, Elisha P.; Basu, Niladri

    2015-01-01

    Mercury is utilized worldwide in artisanal and small-scale gold mining (ASGM) and may pose a risk for miners and mining communities. While a number of studies have characterized mercury in ASGM communities, most have focused on a single media and few have taken a holistic approach. Here, a multiple media exposure assessment and cross-sectional study of mercury was conducted in 2010 through 2012 in northeast Ghana with a small-scale gold mining community, Kejetia, a subsistence farming community, Gorogo, and an urban ASGM gold refinery in Bolgatanga. The objective was to assess mercury in a range of human (urine and hair) and ecological (household soil, sediment, fish, and ore) samples to increase understanding of mercury exposure pathways. All participants were interviewed on demographics, occupational and medical histories, and household characteristics. Participants included 90 women of childbearing age and 97 adults from Kejetia and 75 adults from Gorogo. Median total specific gravity-adjusted urinary, hair, and household soil mercury were significantly higher in Kejetia miners (5.18 µg/L, 0.967 µg/g, and 3.77 µg/g, respectively) than Kejetia non-miners (1.18 µg/L, 0.419 µg/g, and 2.00 µg/g, respectively) and Gorogo participants (0.154 µg/L, 0.181 µg/g, and 0.039 µg/g) in 2011. Sediment, fish, and ore Hg concentrations were below guideline values. Median soil mercury from the Bolgatanga refinery was very high (54.6 µg/g). Estimated mean mercury ingestion for Kejetia adults from soil and dust exceeded the U.S. Environmental Protection Agency reference dose (0.3 µg Hg/kg·day) for pica (0.409 µg Hg/kg·day) and geophagy (20.5 µg Hg/kg·day) scenarios. Most participants with elevated urinary and household soil mercury were miners, but some non-miners approached and exceeded guideline values, suggesting a health risk for non-mining residents living within these communities. PMID:26340636

  18. Small-scale variability of the current in the Strait of Bonifacio

    NASA Astrophysics Data System (ADS)

    Gérigny, Olivia; Coudray, Sylvain; Lapucci, Chiara; Tomasino, Corinne; Bisgambiglia, Paul-Antoine; Galgani, François

    2015-08-01

    Current dynamics in the Strait of Bonifacio (south Corsica) were investigated at a small scale during the STELLAMARE1 multidisciplinary cruise in summer 2012, using in situ measurements and modeling data. The Strait of Bonifacio is a particularly sensitive marine area in which specific conservation measures have been taken to preserve the natural environment and wild species. Good knowledge of the hydrodynamics in this area is essential to optimize the Marine Protected Area's management rules. Therefore, we used a high-resolution model (400 m) based on the MARS3D code to investigate the main flux exchanges and to formulate certain hypotheses about the formation of possible eddy structures. The aim of the present paper is first to synthetize the results obtained by combining Acoustic Doppler Current Profiler data, hydrological parameters, Lagrangian drifter data, and satellite observations such as MODIS OC5 chlorophyll a data or Metop-A AVHRR Sea Surface Temperature (SST) data. These elements are then used to validate the presence of the mesoscale eddies simulated by the model and their recurrence outside the cruise period. To complete the analysis, the response of the 3D hydrodynamical model was evaluated under two opposing wind systems and certain biases were detected. Strong velocities up to 1 m s-1 were recorded in the east part due to the Venturi effect; a complementary system of vortices governed by Coriolis effect and west wind was observed in the west part, and horizontal stratification in the central part has been identified under typical wind condition.

  19. Variability of macrobenthic assemblages under abnormal climatic conditions in a small scale tropical estuary

    NASA Astrophysics Data System (ADS)

    Lucero R., Carlos H.; Cantera K., Jaime R.; Romero, Isabel C.

    2006-06-01

    Macrobenthic assemblages associated with mangrove mud flats were studied at three stations in the Dagua River Estuary (Colombian coast, Tropical Eastern Pacific) to assess broad distribution patterns with relation to hydrographical and sediment conditions during the cold (La Niña) phase of the 1997-2000 El Niño/Niña Phenomenon (ENSO Niño/Niña). During the study period, abnormal water and interstitial temperature, high dissolved oxygen and low salinity conditions were present in the water column of the small scale (5.5 km long) estuary, reducing its extension and moving estuarine conditions downstream. Sediment samples were collected for sediment analysis (grain size, water content) and biological studies (specific composition, relative abundance, diversity, evenness and trophic structure) from quadrates (25 × 25 cm) located in the lower, middle and upper regions of the estuary. Macrobenthic assemblages at the upper estuary were composed of 78 species and dominated by Tanaidaceans, suggesting the direct effect of freshwater inflow, and by some polychaetes in the lower region, showing marine influence. Diversity and evenness increased along the salinity gradient from the upper region of the estuary towards the lower region. Surface deposit feeders (SDF, 72.2%) and sub-surface deposit feeders (SSDF, 21%) were dominant as trophic groups. SDF were the most abundant group in the upper estuary, SSDF dominated the lower estuary. These patterns were controlled by the abnormal conditions generated by the cold phase of ENSO (Niño/Niña) in water temperature, higher deposition of organic matter and low salinity that changed the estuarine's typical macrobenthic assemblage structure, with dominance of marine species to one characterized by few abundant freshwater species (Tanaidaceans, insects).

  20. The Spatial Distribution of Satellite Galaxies within Halos: Measuring the Very Small Scale Angular Clustering of SDSS Galaxies

    NASA Astrophysics Data System (ADS)

    Piscionere, Jennifer A.; Berlind, Andreas A.; McBride, Cameron K.; Scoccimarro, Román

    2015-06-01

    We measure the angular clustering of galaxies from the Sloan Digital Sky Survey (SDSS) Data Release 7 in order to probe the spatial distribution of satellite galaxies within their dark matter halos. Specifically, we measure the angular correlation function on very small scales (7″–320″) in a range of luminosity threshold samples (absolute r-band magnitudes from ‑18 up to ‑21) that are constructed from the subset of SDSS that has been spectroscopically observed more than once (the so-called plate overlap region). We choose to measure angular clustering in this reduced survey footprint in order to minimize the effects of fiber collision incompleteness, which are otherwise substantial on these small scales, and we discuss the possible impact that fiber collisions have on our measurements. We model our clustering measurements using a fully numerical halo model that populates dark matter halos in N-body simulations to create realistic mock galaxy catalogs. The model has free parameters that specify both the number and spatial distribution of galaxies within their host halos. We adopt a flexible density profile for the spatial distribution of satellite galaxies that is similar to the dark matter Navarro–Frenk–White (NFW) profile, except that the inner slope is allowed to vary. We find that the angular clustering of our most luminous samples ({{M}r} < ‑20 and ‑21) suggests that luminous satellite galaxies have substantially steeper inner density profiles than NFW. Lower-luminosity samples are less constraining, however, and are consistent with satellite galaxies having shallow density profiles. Our results confirm the findings of Watson et al. while using different clustering measurements and modeling methodology.

  1. Fungi at a Small Scale: Spatial Zonation of Fungal Assemblages around Single Trees

    PubMed Central

    Branco, Sara; Bruns, Thomas D.; Singleton, Ian

    2013-01-01

    Biological communities are often structured by environmental factors even at small spatial scales. Fungi are no exception, though the patterns and mechanisms underlying their community structure are usually unknown. Previous work documented zonation in fungi under tree canopies primarily through their fruiting patterns. Here we investigate the existence of zonation patterns in fungal communities around isolated Pinus muricata trees of different ages in northern coastal California. Using a combination of ingrowth bags and pyrosequencing to target underground mycelium we found highly diverse soil fungal communities associated with single trees. Both ectomycorrhizal and non-ectomycorrhizal fungi were present in all samples, but the latter were more species rich, dominated the samples by sequence read abundance, and showed partitioning by canopy-defined zones and tree age. Soil chemistry was correlated with fungal zonation, but host root density was not. Our results indicate different guilds of fungi partition space differently and are driven by distinct environmental parameters. PMID:24147130

  2. Small-scale spatial variations of gaseous air pollutants - A comparison of path-integrated and in situ measurement methods

    NASA Astrophysics Data System (ADS)

    Ling, Hong; Schäfer, Klaus; Xin, Jinyuan; Qin, Min; Suppan, Peter; Wang, Yuesi

    2014-08-01

    Traffic emissions are a very important factor in Beijing's urban air quality. To investigate small-scale spatial variations in air pollutants, a campaign was carried out from April 2009 through March 2011 in Beijing. DOAS (differential optical absorption spectroscopy) systems and in situ instruments were used. Atmospheric NO, NO2, O3 and SO2 mixing ratios were monitored. Meanwhile, HCHO mixing ratios were measured by two different DOAS systems. Diurnal variations of these mixing ratios were analysed. Differences between the path-integrated and in situ measurements were investigated based on the results from the campaign. The influences of different weather situations, dilution conditions and light-path locations were investigated as well. The results show that the differences between path-integrated and in situ mixing ratios were affected by combinations of emission source strengths, weather conditions, chemical transformations and local convection. Path-integrated measurements satisfy the requirements of traffic emission investigations better than in situ measurements.

  3. Small-scale variability in suspended matter associated with the Connecticut River plume front

    NASA Astrophysics Data System (ADS)

    Ackleson, Steven G.; O'Donnell, James

    2011-10-01

    We report high spatial resolution observations of optical proxies for suspended particles and dissolved matter measured at the boundary of the Connecticut River plume (CRP) in Long Island Sound (LIS) in April 2000 when river discharge was near the annual maximum. The magnitude of beam attenuation, cp, backscatter, bb, and absorption at short wavelengths indicated higher concentration of suspended particles and colored dissolved matter within the LIS relative to the adjacent CRP. The fractional backscatter from particles indicated relatively higher organic matter fraction within the LIS. An absorption feature centered at 429 nm (aPB), indicated the presence of pigmented heterotrophic bacteria unique to the LIS and the strongest signals were observed at locations closest to shore. The spectral slope of beam attenuation associated with particulate matter (γ) indicated the presence of relatively larger particle assemblages within the LIS. Strong linear relationships between γ and salinity were observed within the energetic CRP boundary region, within 30 m of the front location. Regression residuals indicated a shift to smaller particles and were greatest at the front and decreased with distance toward the plume interior with a length scale similar to previous reports of the kinetic energy dissipation rate. At the same time, the magnitude of cp and bb remained uniform. These results are consistent with the disruption of low fractal dimension particle assemblages due to enhanced turbulence and mixing. The residuals in γ were weakly correlated with salinity and aPB suggesting that aggregate disruption was primarily associated with entrained Long Island Sound water.

  4. Active moss biomonitoring of small-scale spatial distribution of airborne major and trace elements in the Belgrade urban area.

    PubMed

    Vuković, Gordana; Aničić Urošević, Mira; Razumenić, Ivana; Goryainova, Zoya; Frontasyeva, Marina; Tomašević, Milica; Popović, Aleksandar

    2013-08-01

    In urban environments, human exposure to air pollutants is expected to be significantly increased, especially near busy traffic streets, street canyons, tunnels, etc. where urban topography and microclimate may additionally cause poor air conditions giving rise to pollution hotspots. As a practical and cost-effective approach, active moss biomonitoring survey of some major and trace element air pollution was performed in the Belgrade street canyons and city tunnel in 2011 with the aim to evaluate possibility of using Sphagnum girgensohnii moss bags for investigation of the small-scale vertical and horizontal distribution patterns of the elements. In five street canyons, the moss bags were hung at heights of about 4, 8 and 16 m, during 10 weeks, and also, for the same time, the moss bags were exposed in the tunnel, in front of and out of it. After the exposure period, the concentrations of Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Sr, V and Zn in the moss were determined by inductively coupled plasma optical emission spectrometry. According to the results, in all street canyons, the vertical distribution patterns of the moss elements concentration (Al, Ba, Co, Cr, Cu, Ni, Pb, Sr, V and Zn) showed statistically significant decrease from the first to the third heights of bags exposure. In the tunnel experiment, from inner to out of the tunnel, for Al, Ba, Cd, Co, Cr, Cu, Fe, K and Zn, decreasing trend of concentrations was obtained. Significantly higher concentration of the elements was pronounced for the tunnel in comparison with the street canyons. The results indicate that the use of S. girgensohnii moss bags is a simple, sensitive and inexpensive way to monitor the small-scale inner city spatial distribution of airborne major and trace element content. PMID:23430735

  5. Small scale variability of transport and composition of dissolved organic matter in the subsoil

    NASA Astrophysics Data System (ADS)

    Leinemann, Timo; Kalbitz, Karsten; Mikutta, Robert; Guggenberger, Georg

    2016-04-01

    Dissolved organic matter (DOM) is the most mobile fraction of carbon in the soil and connects the carbon-rich topsoil with the subsoil where translocated OM may get stabilized. The water flux in soil is highly heterogeneous, both temporarily and spatially. We, therefore, hypothesize that at high flow velocities, DOM can bypass possible mineral binding sites and microorganisms, thus leading to less degraded DOM under high flow velocities. To address this question, we investigated water and DOM fluxes in situ using segmented suction plates (4 x 4 segments on 24 x 24 cm) installed into three soil observatories at three depths (10 cm, 50 cm, and 150 cm) in a Podzolic Cambisol under Beech (Fagus sylvatica) near Hannover, Germany. To follow the transport of carbon from the litter layer through the soil, an in situ 13C-labelling experiment has been conducted in January 2015. Concentration of dissolved organic carbon (DOC) and DOM composition was analyzed using high temperature combustion and photometric methods. The amount of transported DOC decreased by ca. 80% from 10 to 50 cm depth and by 40% from 50 to 150 cm depth. Different flow patterns existed at the centimeter scale, which were stable over time for individual suction plate segments. The specific UV280 nm absorbance of DOM decreased with increasing soil depth. This indicates a selective loss of aromatic compounds. The influence of different flow regimes on the DOM quality became apparent in the subsoil samples (>50 cm depth) showing a correlation of increasing UV280 nm absorbance with increasing water flux. Together with juvenile DO14C up to 150 cm depth this can be an indication for the importance of preferential flow on carbon transport to subsoil.

  6. HF radar observations of small-scale surface current variability in the Straits of Florida

    NASA Astrophysics Data System (ADS)

    Parks, A. B.; Shay, L. K.; Johns, W. E.; Martinez-Pedraja, J.; Gurgel, K.-W.

    2009-08-01

    A dual-station high-frequency Wellen radar (WERA), transmitting at 16.045 MHz, was deployed along the eastern Florida Shelf and operated and maintained by the University of Miami's Rosenstiel School of Marine and Atmospheric Science. From September 2004 to June 2005, a moored acoustic Doppler current profiler (ADCP) acquired subsurface current measurements within the radar footprint along the shelf break at 86-m depth. The shallowest ADCP bin located at 14-m depth was used as a comparison for the WERA surface measurements. RMS differences ranged from 0.1 to 0.3 m s-1 between the surface and 14-m depth, with good agreement over most of the period. Regression analyses indicated slopes near unity in the north-south (v) component and ≈0.5 for the east-west (u) component velocities. When utilized in tandem with the ADCP subsurface measurements, WERA enables three-dimensional snapshots of coastal oceanographic features to be resolved. For example, from December 2004 through February 2005, three energetic circulation patterns were observed: (1) a subsurface stratified countercurrent, (2) a submesoscale coherent vortex, and (3) a mesoscale circulation feature, i.e., a propagating Tortugas gyre. These features represent the significant current variability along the western flank of the Florida Current that impacts the coastal ocean.

  7. Effect of microtopography and species composition on small-scale variability of CO2 fluxes in a subalpine grassland

    NASA Astrophysics Data System (ADS)

    Galvagno, Marta; Filippa, Gianluca; Cremonese, Edoardo; Morra di Cella, Umberto; Isabellon, Michel

    2015-04-01

    Grassland ecosystems cover around 30% of the Earth's land surface and consequently play an important role in the terrestrial carbon balance. Climate and land use changes have a significant effect on the sink/source strength of grasslands, especially in mountain regions. For these reasons the carbon cycle of high-altitude grasslands has recently received higher attention, however little is know on the within-ecosystem variability in CO2 fluxes. In fact, alpine and subalpine grasslands are often characterized by complex topography which generates differences in snowmelt dynamics at site level and related different microhabitats. The deriving patchy distribution of vegetation leads to the coexistence of different plant functional traits and developmental strategies within the same ecosystem. In this study we evaluated the effect of microtopography and associated vegetation types on the CO2 flux components of an unamanaged subalpine grassland located at 2160 m asl, by means of automated clear and opaque chambers. In order to disentangle the contribution of different growth forms to the whole ecosystem carbon sequestration we compare chambers with eddy covariance CO2 flux data. Results show that: i) different growth forms are associated with concave o convex shapes of the terrain and, in detail, grass species dominate in convex areas while forbs are especially found in concave ones ii) two distinct CO2 flux trajectories associated to these shapes can be distinguished in this ecosystem: graminoids show a later beginning of the carbon uptake period but higher CO2 net uptake (NEE), while forbs develop just after snowmelt but show lower NEE. The observed small-scale patterns of carbon sequestration may reflect the distinct vegetation type responses to snowmelt and different adaptations to resource use efficiency (light, temperature, nutrients) specific of their own microhabitat. Further investigations will be carried on to better evaluate the role of microhabitat

  8. On the effects of small-scale variability on acoustic propagation in Fram Strait: The tomography forward problem.

    PubMed

    Dushaw, Brian D; Sagen, Hanne; Beszczynska-Möller, Agnieszka

    2016-08-01

    Acoustic tomography systems have been deployed in Fram Strait over the past decade to complement existing observing systems there. The observed acoustic arrival patterns are unusual, however, consisting of a single, broad arrival pulse, with no discernible repeating patterns or individual ray arrivals. The nature of these arrivals is caused by vigorous acoustic scattering from the small-scale processes that dominate ocean variability in Fram Strait. Simple models for internal wave and mesoscale variability were constructed and tailored to match the variability observed by moored thermisters in Fram Strait. The internal wave contribution to variability is weak. Acoustic propagation through a simulated ocean consisting of a climatological sound speed plus mesoscale and internal wave scintillations obtains arrival patterns that match the characteristics of those observed, i.e., pulse width and travel time variation. The scintillations cause a proliferation of acoustic ray paths, however, reminiscent of "ray chaos." This understanding of the acoustic forward problem is prerequisite to designing an inverse scheme for estimating temperature from the observed travel times. PMID:27586755

  9. Modelling Pesticide Leaching At Column, Field and Catchment Scales Ii. Influence of Soil Variability On Small Scale Transfer Properties

    NASA Astrophysics Data System (ADS)

    Roulier, S.; Jarvis, N.

    The aim of this study was to investigate the differences in small scale transfer prop- erties in relation to variability of soil characteristics in a small undulating agricultural catchment (Vemmenhög, 9 km2), where texture and organic C content are strongly related to landscape position (see Gärdenäs et al., this session). Undisturbed soil col- umn samples (20 cm diameter, 20 cm height) were taken at two locations (4 columns at each location): on a hilltop (high clay content), and in a hollow (high C content). Transient leaching experiments for a tracer and a herbicide (MCPA) were carried out in two steps. After a first application of solute and pesticide the columns were ex- posed to natural rainfall. After one pore volume of drainage had flowed through the columns, they were transferred indoors. A second dose of tracer and pesticide was applied, and the columns were irrigated with half a pore volume of natural rainwa- ter. The breakthrough curves obtained for the hilltop columns showed strong evidence of macroporous flow. The flux concentrations and the resident concentration at the end of the experiment measured for the hollow columns suggested that the loss of pesticide from those columns is little. The MACRO model and the inverse modelling package SUFI were used to estimate the small scale parameters for water transfer, so- lute transport, and pesticide. Good agreement was obtained between model and data. Macroporous flow and diffusive transport through hilltop columns was highlighted by the high calibrated values of the effective diffusion pathlength and the dispersivity. As a consequence of the significant organic C content in the hollows, the value of the degradation rate coefficient for hollow columns was important. In both hilltop and hollow columns, the variation of the degradation rate coefficient between the first and the second application of MCPA showed the ability of the micro-organisms to adapt to the pesticide.

  10. Assessment of small-scale variability of rainfall and multisatellite precipitation estimates using a meso-rain gauge network measurements from southern peninsular India

    NASA Astrophysics Data System (ADS)

    Sunilkumar, K.; Narayana Rao, T.; Satheeshkumar, S.

    2015-10-01

    This paper describes the establishment of a dense rain gauge network and small-scale variability in rain storms (both in space and time) over a complex hilly terrain in southeast peninsular India. Three years of high-resolution gauge measurements are used to evaluate 3 hourly rainfall and sub-daily variations of four widely used multisatellite precipitation estimates (MPEs). The network consists of 36 rain gauges arranged in a near-square grid area of 50 km × 50 km with an intergauge distance of ~ 10 km. Morphological features of rainfall in two principal monsoon seasons (southwest monsoon: SWM and northeast monsoon: NEM) show marked seasonal differences. The NEM rainfall exhibits significant spatial variability and most of the rainfall is associated with large-scale systems (in wet spells), whereas the contribution from small-scale systems is considerable in SWM. Rain storms with longer duration and copious rainfall are seen mostly in the western quadrants in SWM and northern quadrants in NEM, indicating complex spatial variability within the study region. The diurnal cycle also exhibits marked spatiotemporal variability with strong diurnal cycle at all the stations (except for 1) during the SWM and insignificant diurnal cycle at many stations during the NEM. On average, the diurnal amplitudes are a factor 2 larger in SWM than in NEM. The 24 h harmonic explains about 70 % of total variance in SWM and only ~ 30 % in NEM. The late night-mid night peak (20:00-02:00 LT) observed during the SWM is attributed to the propagating systems from the west coast during active monsoon spells. Correlograms with different temporal integrations of rainfall data (1, 3, 12, 24 h) show an increase in the spatial correlation with temporal integration, but the correlation remains nearly the same after 12 h of integration in both the monsoons. The 1 h resolution data shows the steepest reduction in correlation with intergauge distance and the correlation becomes insignificant after ~30

  11. Small-scale spatial variation in near-surface turbidites around the JFAST site near the Japan Trench

    NASA Astrophysics Data System (ADS)

    Yoshikawa, Shuro; Kanamatsu, Toshiya; Kasaya, Takafumi

    2016-03-01

    This paper aims to improve our understanding of the depositional processes associated with turbidites related to recent earthquake events. A series of short sediment cores (ca. 20-30 cm long) were recovered from the landward slope of the Japan Trench around JFAST (Japan Trench Fast Drilling Project) site C0019 by a remotely operated vehicle, KAIKO 7000 II, and the sample sites were accurately located using an LBL (long base line) acoustic navigation system. The properties of the cores were analyzed using visual observations, soft X-ray radiographs, smear slides, measurement of anisotropy of magnetic susceptibility, and analysis of radioactive elements (134Cs, 137Cs, and excess 210Pb). For the first time, small-scale (ca. 200-1000 m) spatial variations in recent earthquake-triggered deep-sea turbidites, the formation of which was probably linked to the 2011 Tohoku-oki earthquake, are described. We also examine the submarine landslide that probably generated the sediment unit below the turbidites, which is thought to be an important process in the study area. The spatial distribution and characteristics of the near-surface seismoturbidite obtained immediately after the earthquake, presented here, will enable precise calibration of offshore evidence of recent earthquakes, and thus facilitate the use of the sedimentary archive for paleoseismic interpretations. Furthermore, although sampling for turbidite seismology on steep slopes has not been widely performed previously, our results suggest that the recent event deposits may be continuously tracked from the slope to the basin using a combination of the present sampling method and conventional large-scale investigation techniques.

  12. Drivers of small scale variability in soil-atmosphere fluxes of CH4, N2O and CO2 in a forest soil

    NASA Astrophysics Data System (ADS)

    Maier, Martin; Nicolai, Clara; Wheeler, Denis; Lang, Friedeike; Paulus, Sinikka

    2016-04-01

    Soil-atmosphere fluxes of CH4, N2O and CO2 can vary on different spatial scales, on large scales between ecosystems but also within apparently homogenous sites. While CO2 and CH4 consumption is rather evenly distibuted in well aerated soils, the production of N2O and CH4 seems to occur at hot spots that can be associated with anoxic or suboxic conditions. Small-scale variability in soil properties is well-known from field soil assesment, affecting also soil aeration and thus theoretically, greenhouse gas fluxes. In many cases different plant species are associated with different soil conditions and vegetation mapping should therefor combined with soil mapping. Our research objective was explaining the small scale variability of greenhouse gas fluxes in an apparently homogeneous 50 years old Scots Pine stand in a former riparian flood plain.We combined greenhouse gas measurements and soil physical lab measurments with field soil assessment and vegetation mapping. Measurements were conducted with at 60 points at a plot of 30 X 30 m at the Hartheim monitoring site (SW Germany). For greenhouse gas measurements a non-steady state chamber system and laser analyser, and a photoacoustic analyser were used. Our study shows that the well aerated site was a substantial sink for atmospheric CH4 (-2.4 nmol/m² s) and also a for N2O (-0.4 nmol/m² s), but less pronounced, whereas CO2 production was a magnitude larger (2.6 μmol/m² s). The spatial variability of the CH4 consumption of the soils could be explained by the variability of the soil gas diffusivity (measured in situ + using soil cores). Deviations of this clear trend were only observed at points where decomposing woody debris was directly under the litter layer. Soil texture ranged from gravel, coarse sand, fine sand to pure silt, with coarser texture having higher soil gas diffusivity. Changes in texture were rather abrupt at some positions or gradual at other positions, and were well reflected in the vegetation

  13. Small-scale variability of chlorophyll, CDOM, and suspended matter in the Lake Balaton as obtained by shipborne UV fluorescent lidar

    NASA Astrophysics Data System (ADS)

    Pelevin, Vadim; Palmer, Stephanie; Khymchenko, Lisa

    2015-04-01

    Despite a long history in oceanography, few attempts have been made to use fluorescent lidars to evaluate water quality in lakes. We report lidar measurements taken on the Lake Balaton over the period of five days in August, 2012. Lake Balaton, the largest lake in Central Europe in area (597 km2), is very shallow (average depth of 3.5m). The lake is mesotrophic exhibiting a strong trophic gradient from SW to NE. The UV fluorescent lidar UFL-9 used in this study was developed at the Shirshov Institute of Oceanology. It can be used for CDOM, organic pollutants, chlorophyll, and suspended matter concentrations measurements at very high spatial resolution (up to ~1 m). The data were collected continuously during daytime while the boat was travelling. The entire area of the lake was covered by the measurement. The lidar data were calibrated against those obtained in situ through water sampling and then converted from the optical units into the mass concentrations of the above mentioned constituents. Based on this data set, we mapped and investigated in detail the small-scale spatial variability of CDOM, chlorophyll-a, and suspended matter concentrations. In particular, the characteristics of patchiness for the selected parameters were quantified and inter-compared, and their relations with the background forcing conditions were analyzed. We also discuss the applicability of lidar techniques for assessing the hydrological and ecological conditions in shallow inland water bodies. The study was partly supported by the Russian Science Foundation, Grant 14-50-00095.

  14. Assessment of small-scale variability of rainfall and multi-satellite precipitation estimates using measurements from a dense rain gauge network in Southeast India

    NASA Astrophysics Data System (ADS)

    Sunilkumar, K.; Narayana Rao, T.; Satheeshkumar, S.

    2016-05-01

    This paper describes the establishment of a dense rain gauge network and small-scale variability in rain events (both in space and time) over a complex hilly terrain in Southeast India. Three years of high-resolution gauge measurements are used to validate 3-hourly rainfall and sub-daily variations of four widely used multi-satellite precipitation estimates (MPEs). The network, established as part of the Megha-Tropiques validation program, consists of 36 rain gauges arranged in a near-square grid area of 50 km × 50 km with an intergauge distance of 6-12 km. Morphological features of rainfall in two principal rainy seasons (southwest monsoon, SWM, and northeast monsoon, NEM) show marked differences. The NEM rainfall exhibits significant spatial variability and most of the rainfall is associated with large-scale/long-lived systems (during wet spells), whereas the contribution from small-scale/short-lived systems is considerable during the SWM. Rain events with longer duration and copious rainfall are seen mostly in the western quadrants (a quadrant is 1/4 of the study region) in the SWM and northern quadrants in the NEM, indicating complex spatial variability within the study region. The diurnal cycle also exhibits large spatial and seasonal variability with larger diurnal amplitudes at all the gauge locations (except for 1) during the SWM and smaller and insignificant diurnal amplitudes at many gauge locations during the NEM. On average, the diurnal amplitudes are a factor of 2 larger in the SWM than in the NEM. The 24 h harmonic explains about 70 % of total variance in the SWM and only ˜ 30 % in the NEM. During the SWM, the rainfall peak is observed between 20:00 and 02:00 IST (Indian Standard Time) and is attributed to the propagating systems from the west coast during active monsoon spells. Correlograms with different temporal integrations of rainfall data (1, 3, 12, 24 h) show an increase in the spatial correlation with temporal integration, but the

  15. Spatial distribution and statistical properties of small-scale convective vortex-like motions in a quiet-Sun region

    NASA Astrophysics Data System (ADS)

    Vargas Domínguez, S.; Palacios, J.; Balmaceda, L.; Cabello, I.; Domingo, V.

    2011-09-01

    High-resolution observations of a quiet-Sun internetwork region taken with the Solar 1-m Swedish Telescope in La Palma are analysed. We determine the location of small-scale vortex motions in the solar photospheric region by computing the horizontal proper motions of small-scale structures on time-series of images. These plasma convectively driven swirl motions are associated to (1) downdrafts (that have been commonly explained as corresponding to sites where the plasma is cooled down and hence returned to the interior below the visible photospheric level) and (2) horizontal velocity vectors converging on a central point. The sink cores are proved to be the final destination of passive floats tracing plasma flows towards the centre of each vortex. We establish the occurrence of these events to be 1.4 × 10-3 and 1.6 × 10-3 vortices Mm-2 min-1, respectively, for the two time-series analysed here.

  16. Small scale variability of soil parameters in different land uses on the southern slopes of Mount Kilimanjaro

    NASA Astrophysics Data System (ADS)

    Bogner, Christina; Kühnel, Anna; Hepp, Johannes; Huwe, Bernd

    2016-04-01

    The Kilimanjaro region in Tanzania constitutes a particularity compared to other areas in the country. Because enough water is available the population grows rapidly and large areas are converted from natural ecosystems to agricultural areas. Therefore, the southern slopes of Mt. Kilimanjaro encompass a complex mosaic of different land uses like coffee plantations, maize, agroforestry or natural savannah. Coffee is an important cash crop in the region and is owned mostly by large companies. In contrast, the agroforestry is a traditional way of agriculture and has been sustained by the Chagga tribe for centuries. These so called homegardens are organised as multi-level systems and contain a mixture of different crops. Correlations in soil and vegetation data may serve as indicators for crop and management impacts associated to different types of land use. We hypothesize that Chagga homegardens, for example, show a more pronounced spatial autocorrelation compared to coffee plantations due to manifold above and belowground crop structures, whereas the degree of anisotropy is assumed to be higher in the coffee sites due to linear elements in management. Furthermore, we hypothesize that the overall diversity of soil parameters in homegardens on a larger scale is higher, as individual owners manage their field differently, whereas coffee plantation management often follows general rules. From these general hypotheses we derive two specific research questions: a) Are there characteristic differences in the spatial organisation of soil physical parameters of different land uses? b) Is there a recognizable relationship between vegetation structure and soil physical parameters of topsoils? We measured soil physical parameters in the topsoil (bulk density, stone content, texture, soil moisture and penetration resistance). Additionally, we took spectra of soil samples with a portable VIS-NIR spectrometer to determine C and N and measured leaf area index and troughfall as an

  17. Small Scale Organic Techniques

    ERIC Educational Resources Information Center

    Horak, V.; Crist, DeLanson R.

    1975-01-01

    Discusses the advantages of using small scale experimentation in the undergraduate organic chemistry laboratory. Describes small scale filtration techniques as an example of a semi-micro method applied to small quantities of material. (MLH)

  18. Small Scale Assessment of Spatial and Vertical Redistribution of Fukushima Fallouts Radiocaesium in Contaminated Soil Using in-situ HPGe Gamma Ray Spectrometry

    NASA Astrophysics Data System (ADS)

    Patin, J.; Onda, Y.; Yoda, H.; Kato, H.

    2011-12-01

    After Tohoku earthquake on March 11th 2011, the subsequent tsunami and the resulting Fukushima Daiichi Nuclear Power Plant disaster, gamma emitting particles, first release into the atmosphere, were quickly deposited on the soil surface, with potentially harmful level in the surroundings of the nuclear power plant. Thus, the evaluation of soil deposition pattern, depth migration and afterward radionuclides redistribution and export by erosion and hydrological processes is fundamental for contamination assessments and to plan future actions. Our study site is located 37km from Fukushima power plant, inside the evacuated zone. In this study, we used a bounded erosion plot of 22.1m x 5m to assess global export of sediments and 137Cs. This plot, previously cropped with tobacco, is morphologically divided into inter-rill areas separated by rills that formed into former wheel tracks. The bottom of the plot is subject to deposition of sediments. In order to determine and quantify the internal processes responsible of the export of sediment, the depth distribution of 137Cs is estimated using a portable High Purity Germanium (HPGe) detector. Such a portable device, associated to the high radiation levels, allow an acquisition of spatially distributed data within the plot in a reasonable time (1 min/sample). At the same time, depth distribution of 137Cs are measured using the scrapper plate technique, adapted to obtain a fine resolution in the first, highly contaminated, centimeters of soil. Finally, 137Cs depth profiles, associated with in situ and laboratory gamma spectrums acquired with the portable detector, allow for the detector calibration. Although the initial deposit can reasonably be supposed homogeneous at the plot scale, the dataset obtained 3 months later shows high spatial and temporal variability due to erosion processes. Measurements with the portable HPGe detector proved to be useful at this small scale, avoiding the needs of a large number of soil samples

  19. SIMULATED IMPACTS OF SMALL-SCALE SPATIAL DISTRIBUTION OF IMPERVIOUS AREA ON RUNOFF RESPONSE OF FIELD-SCALE CATCHMENTS

    EPA Science Inventory

    Impervious surface is known to negatively affect catchment hydrology through both its extent and spatial distribution. In this study, we empirically quantify via model simulations the impacts of different configurations of impervious surface on watershed response to rainfall. An ...

  20. Spatial modeling of personalized exposure dynamics: the case of pesticide use in small-scale agricultural production landscapes of the developing world

    PubMed Central

    Leyk, Stefan; Binder, Claudia R; Nuckols, John R

    2009-01-01

    Background Pesticide poisoning is a global health issue with the largest impacts in the developing countries where residential and small-scale agricultural areas are often integrated and pesticides sprayed manually. To reduce health risks from pesticide exposure approaches for personalized exposure assessment (PEA) are needed. We present a conceptual framework to develop a spatial individual-based model (IBM) prototype for assessing potential exposure of farm-workers conducting small-scale agricultural production, which accounts for a considerable portion of global food crop production. Our approach accounts for dynamics in the contaminant distributions in the environment, as well as patterns of movement and activities performed on an individual level under different safety scenarios. We demonstrate a first prototype using data from a study area in a rural part of Colombia, South America. Results Different safety scenarios of PEA were run by including weighting schemes for activities performed under different safety conditions. We examined the sensitivity of individual exposure estimates to varying patterns of pesticide application and varying individual patterns of movement. This resulted in a considerable variation in estimates of magnitude, frequency and duration of exposure over the model runs for each individual as well as between individuals. These findings indicate the influence of patterns of pesticide application, individual spatial patterns of movement as well as safety conditions on personalized exposure in the agricultural production landscape that is the focus of our research. Conclusion This approach represents a conceptual framework for developing individual based models to carry out PEA in small-scale agricultural settings in the developing world based on individual patterns of movement, safety conditions, and dynamic contaminant distributions. The results of our analysis indicate our prototype model is sufficiently sensitive to differentiate and

  1. The critical scale of small-scale spatial variation in ecological patterns and processes in intertidal macrobenthic seagrass assemblages

    NASA Astrophysics Data System (ADS)

    Barnes, R. S. K.; Ellwood, M. D. F.

    2012-02-01

    Earlier work on benthic faunal assemblages in intertidal seagrass beds has shown maximal structural variation at spatial scales <150 m. To examine more closely spatial variation of species assemblages within this range, numbers of target taxa in the beds on North Stradbroke Island, Moreton Bay, Australia, were sampled at nested spatial scales of 0.5, 5, 30 and 90 m at two localities 900 m apart. Variance components were largest at the smallest scales, that at 0.5 m comprising 55% of the total and that at 5 m 13%. Individual species were patchily dispersed and their assemblages were randomly structured at all studied spatial scales. Although assemblage composition differed significantly between the two localities, overall faunal abundance and species richness were relatively uniform across the whole study area. These seagrass beds show little turn-over of dominant species and little evidence of niche partitioning through space over scales of <1 km. In this they contrast markedly with the equivalent intertidal dwarf-eelgrass beds of Knysna in South Africa that form a high turn-over, strongly structured, deterministic system.

  2. Spatially-explicit risk profiling of Plasmodium falciparum infections at a small scale: a geostatistical modelling approach

    PubMed Central

    Silué, Kigbafori D; Raso, Giovanna; Yapi, Ahoua; Vounatsou, Penelope; Tanner, Marcel; N'Goran, Eliézer K; Utzinger, Jürg

    2008-01-01

    Background There is a renewed political will and financial support to eradicate malaria. Spatially-explicit risk profiling will play an important role in this endeavour. Patterns of Plasmodium falciparum infection prevalence were examined among schoolchildren in a highly malaria-endemic area. Methods A questionnaire was administered and finger prick blood samples collected from 3,962 children, aged six to 16 years, attending 55 schools in a rural part of western Côte d'Ivoire. Information was gathered from the questionnaire on children's socioeconomic status and the use of bed nets for the prevention of malaria. Blood samples were processed with standardized, quality-controlled methods for diagnosis of Plasmodium spp. infections. Environmental data were obtained from satellite images and digitized maps. Bayesian variogram models for spatially-explicit risk modelling of P. falciparum infection prevalence were employed, assuming for stationary and non-stationary spatial processes. Findings The overall prevalence of P. falciparum infection was 64.9%, ranging between 34.0% and 91.9% at the unit of the school. Risk factors for a P. falciparum infection included age, socioeconomic status, not sleeping under a bed net, distance to health care facilities and a number of environmental features (i.e. normalized difference vegetation index, rainfall and distance to rivers). After taking into account spatial correlation only age remained significant. Non-stationary models performed better than stationary models. Conclusion Spatial risk profiling of P. falciparum prevalence data provides a useful tool for targeting malaria control intervention, and hence will play a role in the quest of local elimination and ultimate eradication of the disease. PMID:18570685

  3. The effects of biotic and abiotic factors on the spatial heterogeneity of alpine grassland vegetation at a small scale on the Qinghai-Tibet Plateau (QTP), China.

    PubMed

    Wen, Lu; Dong, Shi Kui; Li, Yuan Yuan; Sherman, Ruth; Shi, Jian Jun; Liu, De Mei; Wang, Yan Long; Ma, Yu Shou; Zhu, Lei

    2013-10-01

    Understanding the complex effects of biotic and abiotic factors on the composition of vegetation is very important for developing and implementing strategies for promoting sustainable grassland development. The vegetation-disturbance-environment relationship was examined in degraded alpine grasslands in the headwater areas of three rivers on the Qinghai-Tibet Plateau in this study. The investigated hypotheses were that (1) the heterogeneity of the vegetation of the alpine grassland is due to a combination of biotic and abiotic factors and that (2) at a small scale, biotic factors are more important for the distribution of alpine vegetation. On this basis, four transects were set along altitudinal gradients from 3,770 to 3,890 m on a sunny slope, and four parallel transects were set along altitudinal gradients on a shady slope in alpine grasslands in Guoluo Prefecture of Qinghai Province, China. It was found that biological disturbances were the major forces driving the spatial heterogeneity of the alpine grassland vegetation and abiotic factors were of secondary importance. Heavy grazing and intensive rat activity resulted in increases in unpalatable and poisonous weeds and decreased fine forages in the form of sedges, forbs, and grasses in the vegetation composition. Habitat degradation associated with biological disturbances significantly affected the spatial variation of the alpine grassland vegetation, i.e., more pioneer plants of poisonous or unpalatable weed species, such as Ligularia virgaurea and Euphorbia fischeriana, were found in bare patches. Environmental/abiotic factors were less important than biological disturbances in affecting the spatial distribution of the alpine grassland vegetation at a small scale. It was concluded that rat control and light grazing should be applied first in implementing restoration strategies. The primary vegetation in lightly grazed and less rat-damaged sites should be regarded as a reference for devising vegetation

  4. Contribution of Small-Scale Correlated Fluctuations of Microstructural Properties of a Spatially Extended Geophysical Target Under the Assessment of Radar Backscatter

    NASA Technical Reports Server (NTRS)

    Yurchak, Boris S.

    2010-01-01

    The study of the collective effects of radar scattering from an aggregation of discrete scatterers randomly distributed in a space is important for better understanding the origin of the backscatter from spatially extended geophysical targets (SEGT). We consider the microstructure irregularities of a SEGT as the essential factor that affect radar backscatter. To evaluate their contribution this study uses the "slice" approach: particles close to the front of incident radar wave are considered to reflect incident electromagnetic wave coherently. The radar equation for a SEGT is derived. The equation includes contributions to the total backscatter from correlated small-scale fluctuations of the slice's reflectivity. The correlation contribution changes in accordance with an earlier proposed idea by Smith (1964) based on physical consideration. The slice approach applied allows parameterizing the features of the SEGT's inhomogeneities.

  5. Small-Scale Drop-Size Variability: Empirical Models for Drop-Size-Dependent Clustering in Clouds

    NASA Technical Reports Server (NTRS)

    Marshak, Alexander; Knyazikhin, Yuri; Larsen, Michael L.; Wiscombe, Warren J.

    2005-01-01

    By analyzing aircraft measurements of individual drop sizes in clouds, it has been shown in a companion paper that the probability of finding a drop of radius r at a linear scale l decreases as l(sup D(r)), where 0 less than or equals D(r) less than or equals 1. This paper shows striking examples of the spatial distribution of large cloud drops using models that simulate the observed power laws. In contrast to currently used models that assume homogeneity and a Poisson distribution of cloud drops, these models illustrate strong drop clustering, especially with larger drops. The degree of clustering is determined by the observed exponents D(r). The strong clustering of large drops arises naturally from the observed power-law statistics. This clustering has vital consequences for rain physics, including how fast rain can form. For radiative transfer theory, clustering of large drops enhances their impact on the cloud optical path. The clustering phenomenon also helps explain why remotely sensed cloud drop size is generally larger than that measured in situ.

  6. Spatial Variability of VOCl Fluxes From Forest Soil

    NASA Astrophysics Data System (ADS)

    Svensson, T.; Black, A. T.; Fulton, T.; Molodovskaya, M. S.; Nesic, Z.; Pickering, L.; Pilz, J.; Oberg, G.

    2011-12-01

    Naturally formed volatile chlorinated organic compounds (VOCl) are involved in various atmospheric processes such as ozone depletion. These compounds are present in several environmental compartments and some of them are of ecotoxicological concern. Over the past few years, a small but growing literature has focused on the emission of VOCls from terrestrial environments and there are indications that the emissions vary between ecosystems and that spatial and temporal patterns exist. Due to methodological challenges, the studies have hitherto been based on rather few measurements; subsequently estimates of both the magnitude and the variability of the fluxes are quite uncertain. To enable collection of larger sample sets, which would allow reliable surveying of spatial variability, we developed a portable chamber system. The system consists of a non-steady-state chamber (area 0.20 m2, volume 56.9L), a close-looped air-circulation unit with a diaphragm pump, and a VOCl sampling unit with carbon-based adsorbent tubes for later analysis in the laboratory by gas chromatography (GC7890, Agilent Technologies, USA) with micro-ECD detection (Agilent Technologies, USA), a thermal desorption system (TDSA2, Gerstel Inc., USA) and cryocooled inlet system (CIS4, Gerstel Inc., USA). We are using the portable system to investigate the spatial variability of chloroform fluxes at different scales and at various forested sites in south-west British Columbia, Canada. Our pilot observations strongly indicate that the flux from adjacent chambers (0.5-2 m between locations), may vary ten times or more, and that small-scale variability often overrides any larger scale patterns, or differences between sites. In addition, 'hot' and 'cold' measurement locations were not consistent spatially, indicating non-consistent spatial patterns in time. The study highlights that we need to better understand small-scale spatial heterogeneity of VOCl fluxes to interpret larger scale temporal and spatial

  7. Climate SPHINX: High-resolution present-day and future climate simulations with an improved representation of small-scale variability

    NASA Astrophysics Data System (ADS)

    Davini, Paolo; von Hardenberg, Jost; Corti, Susanna; Subramanian, Aneesh; Weisheimer, Antje; Christensen, Hannah; Juricke, Stephan; Palmer, Tim

    2016-04-01

    The PRACE Climate SPHINX project investigates the sensitivity of climate simulations to model resolution and stochastic parameterization. The EC-Earth Earth-System Model is used to explore the impact of stochastic physics in 30-years climate integrations as a function of model resolution (from 80km up to 16km for the atmosphere). The experiments include more than 70 simulations in both a historical scenario (1979-2008) and a climate change projection (2039-2068), using RCP8.5 CMIP5 forcing. A total amount of 20 million core hours will be used at end of the project (March 2016) and about 150 TBytes of post-processed data will be available to the climate community. Preliminary results show a clear improvement in the representation of climate variability over the Euro-Atlantic following resolution increase. More specifically, the well-known atmospheric blocking negative bias over Europe is definitely resolved. High resolution runs also show improved fidelity in representation of tropical variability - such as the MJO and its propagation - over the low resolution simulations. It is shown that including stochastic parameterization in the low resolution runs help to improve some of the aspects of the MJO propagation further. These findings show the importance of representing the impact of small scale processes on the large scale climate variability either explicitly (with high resolution simulations) or stochastically (in low resolution simulations).

  8. Variability of the raindrop size distribution at small spatial scales

    NASA Astrophysics Data System (ADS)

    Berne, A.; Jaffrain, J.

    2010-12-01

    Because of the interactions between atmospheric turbulence and cloud microphysics, the raindrop size distribution (DSD) is strongly variable in space and time. The spatial variability of the DSD at small spatial scales (below a few km) is not well documented and not well understood, mainly because of a lack of adequate measurements at the appropriate resolutions. A network of 16 disdrometers (Parsivels) has been designed and set up over EPFL campus in Lausanne, Switzerland. This network covers a typical operational weather radar pixel of 1x1 km2. The question of the significance of the variability of the DSD at such small scales is relevant for radar remote sensing of rainfall because the DSD is often assumed to be uniform within a radar sample volume and because the Z-R relationships used to convert the measured radar reflectivity Z into rain rate R are usually derived from point measurements. Thanks to the number of disdrometers, it was possible to quantify the spatial variability of the DSD at the radar pixel scale and to show that it can be significant. In this contribution, we show that the variability of the total drop concentration, of the median volume diameter and of the rain rate are significant, taking into account the sampling uncertainty associated with disdrometer measurements. The influence of this variability on the Z-R relationship can be non-negligible. Finally, the spatial structure of the DSD is quantified using a geostatistical tool, the variogram, and indicates high spatial correlation within a radar pixel.

  9. Small Scale Industries.

    ERIC Educational Resources Information Center

    Rural Development Detwork Bulletin, 1977

    1977-01-01

    Innovative programs for the promotion of small-scale enterprise are being conducted by a variety of organizations, including universities, government agencies, international research institutes, and voluntary assistance agencies. Their activities encompass basic extension services, management of cooperatives, community action programs, and…

  10. Recurrent patterning in the daily foraging routes of hamadryas baboons (Papio hamadryas): spatial memory in large-scale versus small-scale space.

    PubMed

    Schreier, Amy L; Grove, Matt

    2014-05-01

    The benefits of spatial memory for foraging animals can be assessed on two distinct spatial scales: small-scale space (travel within patches) and large-scale space (travel between patches). While the patches themselves may be distributed at low density, within patches resources are likely densely distributed. We propose, therefore, that spatial memory for recalling the particular locations of previously visited feeding sites will be more advantageous during between-patch movement, where it may reduce the distances traveled by animals that possess this ability compared to those that must rely on random search. We address this hypothesis by employing descriptive statistics and spectral analyses to characterize the daily foraging routes of a band of wild hamadryas baboons in Filoha, Ethiopia. The baboons slept on two main cliffs--the Filoha cliff and the Wasaro cliff--and daily travel began and ended on a cliff; thus four daily travel routes exist: Filoha-Filoha, Filoha-Wasaro, Wasaro-Wasaro, Wasaro-Filoha. We use newly developed partial sum methods and distribution-fitting analyses to distinguish periods of area-restricted search from more extensive movements. The results indicate a single peak in travel activity in the Filoha-Filoha and Wasaro-Filoha routes, three peaks of travel activity in the Filoha-Wasaro routes, and two peaks in the Wasaro-Wasaro routes; and are consistent with on-the-ground observations of foraging and ranging behavior of the baboons. In each of the four daily travel routes the "tipping points" identified by the partial sum analyses indicate transitions between travel in small- versus large-scale space. The correspondence between the quantitative analyses and the field observations suggest great utility for using these types of analyses to examine primate travel patterns and especially in distinguishing between movement in small versus large-scale space. Only the distribution-fitting analyses are inconsistent with the field observations, which

  11. Identification of temporal and small-scale spatial variations of phosphate concentration in the near-shore groundwater of an oligotrophic lake

    NASA Astrophysics Data System (ADS)

    Pöschke, Franziska; Schlichting, Hendrik; Lewandowski, Jörg

    2016-04-01

    Lake Stechlin is one of the last oligotrophic lakes in the German North-Eastern Lake District. In recent years there was some worry over a small but continuous increase of phosphate concentrations in the open water body. The reasons remain unclear. Since the lake obtains its water only from groundwater and precipitation there is the assumption that the former can be a significant source of phosphate inputs into the lake. In the present study, three different groundwater sampling settings on different scales in time and space were used to investigate the phosphate concentration in the near-shore groundwater. A multi-level sampling grid of twelve samplers and 60 sampling ports was installed to study the temporal small-scale fluctuations of P concentration in the groundwater and the interstitial water. Furthermore, a one-time sampling campaign of shallow near-shore groundwater was conducted every 500 m along the lake shore. Additionally, nests of permanent groundwater wells were sampled monthly for one year to identify concentration patterns in the deeper aquifer. The results indicate a large spatial and small temporal heterogeneity of P concentrations. The range of P concentration is < 0.01 mg/l up to 0.2 mg/l. There was no significant increase of P concentrations downstream of the small near-shore village Neuglobsow. Since the groundwater catchment belongs since 1938 to a natural protected area other anthropogenic impacts are quite unlikely. Hence, the main source for phosphate is probably the decomposition of naturally present organic material under anaerobic and warm conditions.

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

    NASA Astrophysics Data System (ADS)

    Liu, M.; Bárdossy, A.; Zehe, E.

    2012-12-01

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

  13. Understanding Mountain Range Spatial Variability of Surface Hoar

    NASA Astrophysics Data System (ADS)

    Hendrikx, J.

    2014-12-01

    Surface hoar, once buried often produce a persistent weak layer that is a common instability problem in the snow pack in SW Montana and many other areas around the world. Surface hoar is a common weak layer type in avalanche accidents in a continental and intermountain snowpack. It is however relatively well understood that aspect plays an important role in the spatial location of the growth, and survival of these grain forms, due to the unequal distribution of incoming radiation. However this factor alone does not explain the complex and often confusing spatial pattern of these grains forms throughout the landscape at larger, mountain range spatial scales. In this paper we present a unique data set including over one hundred days of manual observations of surface hoar at sixteen locations on Pioneer Mountain at the Yellowstone Club in southwestern Montana. Using this wealth of observational data located on different aspects, elevations and exposures, coupled with detailed meteorological observations, detailed site scale observations (e.g. Sky view plots) we examine the spatial variability of surface hoar at this scale, and examine the factors that control its spatial distribution. Our results further supports our preliminary work, which shows that small-scale meteorological differences, site scale differences, and local scale lapse rates can greatly influence the spatial variability of surface hoar, over and above that which aspect alone can explain. These results highlight our incomplete understanding of the processes at this large, mountain range scale, and are likely to have implications for both regional and local scale avalanche forecasting in environments where surface hoar cause ongoing instabilities.

  14. Small-scale spatial variability of sub-canopy radiant energy during snowmelt in decidous and confierous forest patches

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In mountainous, forested environments, snowcover dynamics exert a strong control on hydrologic and atmospheric processes. Snowcover ablation patterns in forests are controlled by a complex combination of depositional patterns coupled with radiative and turbulent heat flux patterns related to topogr...

  15. Does Knowledge of Spatial Configuration in Adults with Visual Impairments Improve with Tactile Exposure to a Small-Scale Model of Their Urban Environment?

    ERIC Educational Resources Information Center

    Picard, Delphine; Pry, Rene

    2009-01-01

    This study assessed the efficiency of a model of a familiar urban area for enhancing knowledge of the spatial environment by adults with visual impairments. It found a significant improvement in knowledge of spatial configuration after exposure to the model, suggesting that models are powerful means of developing cognitive mapping in people who…

  16. Measuring spatial variability in soil characteristics

    DOEpatents

    Hoskinson, Reed L.; Svoboda, John M.; Sawyer, J. Wayne; Hess, John R.; Hess, J. Richard

    2002-01-01

    The present invention provides systems and methods for measuring a load force associated with pulling a farm implement through soil that is used to generate a spatially variable map that represents the spatial variability of the physical characteristics of the soil. An instrumented hitch pin configured to measure a load force is provided that measures the load force generated by a farm implement when the farm implement is connected with a tractor and pulled through or across soil. Each time a load force is measured, a global positioning system identifies the location of the measurement. This data is stored and analyzed to generate a spatially variable map of the soil. This map is representative of the physical characteristics of the soil, which are inferred from the magnitude of the load force.

  17. Hot moments and hot spots in hyporheic nutrient transformation - To what degree does small-scale variability control stream-reach attenuation potential?

    NASA Astrophysics Data System (ADS)

    Krause, S.; Blume, T.; Binley, A.; Heathwaite, L.; Cassidy, N. J.; Munz, M.; Tecklenburg, C.; Kaeser, D.

    2011-12-01

    Concentrations of nutrients and contaminants in up-welling groundwater can significantly change along the passage through highly heterogeneous streambed sediments with substantial implications for the quality of connected surface water bodies. This study presents investigations into the physical drivers and chemical controls of nutrient transport and transformation at the aquifer-river interfaces of two upland and lowland UK rivers. It combines the application of in-stream geophysical exploration techniques, multi-level mini-piezometer networks, active and passive heat tracing methods (including fibre-optic distributed temperature sensing - FO-DTS) for identifying hyporheic exchange fluxes and residence time distributions with multi-scale approaches of hyporheic pore water sampling and reactive tracers for analysing the patterns of streambed redox conditions and chemical transformation rates. The analysis of hyporheic pore water from nested multi-level mini piezometers and passive gel probe samplers revealed significant spatial variability in streambed redox conditions and concentration changes of nitrogen species, dissolved oxygen and bioavailable organic carbon. Hot spots of increased nitrate attenuation were identified beneath semi-confining peat lenses in the streambed of the investigated lowland river. The intensity of concentration changes underneath the confining peat pockets correlated with the state of anoxia in the pore water as well as the supply of organic carbon and hyporheic residence times. In contrast, at locations where flow inhibiting peat layers were absent or disrupted - fast exchange between aquifer and river caused a break through of nitrate without significant concentration changes along the hyporheic flow path. Fibre-optic distributed temperature sensor networks and streambed electric resistivity tomography were applied for identifying exchange flow patterns between groundwater and surface water in dependency of streambed structural

  18. Intra-event and Inter-event Ground Motion Variability from 3-D Broadband (0-8 Hz) Ensemble Simulations of Mw 6.7 Thrust Events Including Rough Fault Descriptions, Small-Scale Heterogeneities and Q(f)

    NASA Astrophysics Data System (ADS)

    Withers, K.; Olsen, K. B.; Shi, Z.; Day, S. M.

    2015-12-01

    We model blind thrust scenario earthquakes matching the fault geometry of 1994 Mw 6.7 Northridge earthquake up to 8 Hz by first performing dynamic rupture propagation using a support operator method (SORD). We extend the ground motion by converting the slip-rate data to a kinematic source for the finite difference wave propagation code AWP-ODC, which incorporates an improved frequency-dependent attenuation approach. This technique has high accuracy for Q values down to 15. The desired Q function is fit to the 'effective' Q over the coarse grained-cell for low Q, and a simple interpolation formula is used to interpolate the weights for arbitrary Q. Here, we use a power-law model Q above a reference frequency in the form Q 0 f^n with exponents ranging from 0.0-0.9. We find envelope and phase misfits only slightly larger than that of the elastic case when compared with that of the frequency-wavenumber solution for both a homogenous and a layered model with a large-velocity contrast. We also include small-scale medium complexity in both a 1D layered model and a 3D medium extracted from SCEC CVM-S4 including a surface geotechnical layer (GTL). We model additional realizations of the scenario by varying the hypocenter location, and find that similar moment magnitudes are generated. We observe that while the ground motion pattern changes, the median ground motion is not affected significantly, when binned as a function of distance, and is within 1 interevent standard deviation from the median GMPEs. We find that intra-event variability for the layered model simulations is similar to observed values of single-station standard deviation. We show that small-scale heterogeneity can significantly affect the intra-event variability at frequencies greater than ~1 Hz, becoming increasingly important at larger distances from the source. We perform a parameter space study by varying statistical parameters and find that the variability is fairly independent of the correlation length

  19. Variability of pigment biomass in the California Current system as determined by satellite imagery. I - Spatial variability

    NASA Technical Reports Server (NTRS)

    Smith, Raymond C.; Zhang, Xueyun; Michaelsen, Joel

    1988-01-01

    Spatial variability of chlorophyll in the California Current system was analyzed using Coastal Zone Color Scanner (CZCS) imagery. A total of 48 images were analyzed to produce seasonal averages and variances, gradients, and power spectra. Roughly one third to one half of the variance in pigment biomass can be explained by consistent, large-scale gradients. In general, biomass is higher in the north and in nearshore areas. Nearshore areas also have proportionally more small-scale variability than the areas offshore. Slopes of the power spectra for nearshore areas are about -2.2 (for spatial scales of 10-100 km), while slopes for offshore areas are about -3. In addition, the power spectra show evidence of a change in slope at about 10 km, with slopes of about -1 for shorter-length scales. This may indicate that biological processes dominate the smaller scales, while mesoscale eddies and geostrophic currents dominate the larger scales.

  20. Characteristics of the east Mediterranean dust variability on small spatial and temporal scales

    NASA Astrophysics Data System (ADS)

    Yuval; Sorek-Hamer, Meytar; Stupp, Amnon; Alpert, Pinhas; Broday, David M.

    2015-11-01

    The presence of naturally-occurring dust is a conspicuous meteorological phenomenon characterised by very high load of relatively coarse airborne particulate matter (PM), which may contain also various deleterious chemical and biological materials. Much work has been carried out to study the phenomenon by modelling the generation and transport of dust plumes, and assessment of their temporal characteristics on a large (>1000 km) spatial scale. This work studies in high spatial and temporal resolution the characteristics of dust presence on the mesoscale (>100 km). The small scale variability is important both for better understanding the physical characteristics of the dust phenomenon and for PM exposure specification in epidemiological studies. Unsupervised clustering-based method, using PM10 records and their derived attributes, was developed and applied to detect the impact of dust at the observation locations of a PM10 monitoring array. It was found that dust may cover the whole study area but very often the coverage is partial. On average, the larger the spatial extent of a dust event, the higher and more homogeneous are the associated PM10 concentrations. Dust event lengths however, are only weakly associated with the PM concentrations (Pearson correlation below 0.44). The large PM concentration variability during spatially small events and the fact that their occurrence is strongly correlated with the elevation above sea level of the reporting stations (Pearson correlation 0.87, p-value < 10-5) points to small scale spatiotemporal dynamics of dust plumes.

  1. Spatial variability, structure and composition of crustose algal communities in Diadema africanum barrens

    NASA Astrophysics Data System (ADS)

    Sangil, Carlos; Sansón, Marta; Díaz-Villa, Tania; Hernández, José Carlos; Clemente, Sabrina; Afonso-Carrillo, Julio

    2014-12-01

    Crustose algal communities were studied in Diadema africanum urchin barrens around Tenerife (Canary Islands, NE Atlantic). A hierarchical nested sampling design was used to study patterns of community variability at different spatial scales (sectors, three sides of the island; sites within each sector, 5-10 km apart; stations within each site, 50-100 m apart). Although noncrustose species contributed the most to community richness, cover was dominated by crustose forms, like the coralline algae Hydrolithon farinosum, H. samoënse, H. onkodes, Neogoniolithon orotavicum and N. hirtum, and the phaeophycean Pseudolithoderma adriaticum. The structure of these communities showed high spatial variability, and we found differences in the structure of urchin barrens when compared across different spatial scales. Multivariate analysis showed that variability in community structure was related to the five environmental variables studied (wave exposure, urchin density, substrate roughness, productivity and depth). Wave exposure was the variable that contributed most to community variability, followed by urchin density and substrate roughness. Productivity and depth had limited influence. The effects of these variables differed depending on the spatial scale; wave exposure and productivity were the main variables influencing community changes at the largest scale (between different sectors of the island), while D. africanum density, roughness and depth were the most influential at medium and small scales.

  2. Spatial variability of magnetic soil properties

    NASA Astrophysics Data System (ADS)

    van Dam, Remke L.; Hendrickx, Jan M.; Harrison, Bruce; Borchers, Brian; Norman, David I.; Ndur, Samuel; Jasper, Chris; Niemeyer, Patrick; Nartey, Robert; Vega, David N.; Calvo, Lucas; Simms, Janet E.

    2004-09-01

    The presence of magnetic iron oxides in the soil can seriously hamper the performance of electromagnetic sensors for the detection of buried land mines and unexploded ordnance (UXO). Previous work has shown that spatial variability in soil water content and texture affects the performance of ground penetrating radar and thermal sensors for land mine detection. In this paper we aim to study the spatial variability of iron oxides in tropical soils and the possible effect on electromagnetic induction sensors for buried low-metal land mine and UXO detection. We selected field sites in Panama, Hawaii, and Ghana. Along several horizontal transects in Panama and Hawaii we took closely spaced magnetic susceptibility readings using Bartington MS2D and MS2F sensors. In addition to the field measurements, we took soil samples from the selected sites for laboratory measurements of dual frequency magnetic susceptibility and textural characteristics of the material. The magnetic susceptibility values show a significant spatial variation in susceptibility and are comparable to values reported to hamper the operation of metal detectors in parts of Africa and Asia. The absolute values of susceptibility do not correlate with both frequency dependence and total iron content, which is an indication of the presence of different types of iron oxides in the studied material.

  3. Spatial ascariasis risk estimation using socioeconomic variables.

    PubMed

    Valencia, Luis Iván Ortiz; Fortes, Bruno de Paula Menezes Drumond; Medronho, Roberto de Andrade

    2005-12-01

    Frequently, disease incidence is mapped as area data, for example, census tracts, districts or states. Spatial disease incidence can be highly heterogeneous inside these areas. Ascariasis is a highly prevalent disease, which is associated with poor sanitation and hygiene. Geostatistics was applied to model spatial distribution of Ascariasis risk and socioeconomic risk events in a poor community in Rio de Janeiro, Brazil. Data were gathered from a coproparasitologic and a domiciliary survey in 1550 children aged 1-9. Ascariasis risk and socioeconomic risk events were spatially estimated using Indicator Kriging. Cokriging models with a Linear Model of Coregionalization incorporating one socioeconomic variable were implemented. If a housewife attended school for less than four years, the non-use of a home water filter, a household density greater than one, and a household income lower than one Brazilian minimum wage increased the risk of Ascariasis. Cokriging improved spatial estimation of Ascariasis risk areas when compared to Indicator Kriging and detected more Ascariasis very-high risk areas than the GIS Overlay method. PMID:16506435

  4. Small-Scale-Field Dynamo

    SciTech Connect

    Gruzinov, A.; Cowley, S.; Sudan, R. ||

    1996-11-01

    Generation of magnetic field energy, without mean field generation, is studied. Isotropic mirror-symmetric turbulence of a conducting fluid amplifies the energy of small-scale magnetic perturbations if the magnetic Reynolds number is high, and the dimensionality of space {ital d} satisfies 2.103{lt}{ital d}{lt}8.765. The result does not depend on the model of turbulence, incompressibility, and isotropy being the only requirements. {copyright} {ital 1996 The American Physical Society.}

  5. Spatial impacts of urban structures on micrometeorological variables

    NASA Astrophysics Data System (ADS)

    Koelbing, Merle; Schuetz, Tobias; Weiler, Markus

    2016-04-01

    The heterogeneity of urban surfaces including buildings and the urban vegetation causes high variability of micrometeorological variables on small spatial scales which makes it hard to observe or even predict climate conditions and in particular evapotranspiration with high resolution on the scale of entire cities. Regarding future climate changes and their impacts on urban climate and hydrology the predictability of these small scale variations becomes more and more relevant i.e. for city planners to improve the development of appropriate mitigation strategies. Therefore, new transfer functions for meteorological variables are needed, which consider the structural variability in urban areas and its impacts on the energy balance (shading effects, ventilation, lateral longwave energy fluxes). We approach this goal by testing a mobile meteorological station (the station is mounted on a bicycle trailer and transported by an E-Bike) as a means to derive empirical spatial transfer functions for specific urban structures. We observe air temperature and relative air humidity at 2 different heights, wind direction and speed, incoming and outgoing shortwave radiation as well as infrared temperature from above and below and the four directions. First measurements have been performed in December 2015 at 22 locations in four clusters, which represent manifold different characteristics of urban areas within the city of Freiburg. Every location has been monitored two to six times. Overall, nearly 200 measurements of each variable have been taken. Each measurement takes five minutes. Values are logged every 15 seconds. These measurements were analyzed with regard to a climate station mounted on a rooftop in the proximity of all clusters. Results show a systematic pattern in the differences between the values taken with the fixed and those taken with the mobile climate station, depending on the measurement locations. For example, lower air temperature and higher relative air

  6. May We Identify The Spatial Variability of Soil Hydraulic Properties Based On Measurements With "spatial Tdr"? A) Model Study

    NASA Astrophysics Data System (ADS)

    Zehe, E.; Becker, R.; Schädel, W.

    A dynamic system left without external disturbances, will always tend to a stable equilibrium state that is consistent with the internal physics. For natural soils such an equilibrium state is reached when the gradients of the total hydraulic potential tend to zero. This statement is still valid for heterogeneous soils, because the hydraulic po- tential is an intensive state variable and therefore continuous at discontinuities of the pore space. In contrary the soil water content is as an extensive property discontinu- ous at discontinuities of the pore space. Hence, a small scale soil moisture pattern that persists if the soil state tends to hydraulic equilibrium, reflects the lateral small scale variability of the pore space. The objectives of our study are to show a) whether and how we could use TDR observations to identify the small scale variability of the pore space. For that purpose we analyse artificial TDR measurements, taken from physi- cally based simulations of soil water dynamics in heterogeneous media. b) We want to introduce a new TDR technology which we call "Spatial TDR", that is suitable for that purposes. To produce the artificial TDR-datasets we generate random fields of soil porosity and saturated hydraulic conductivity with different statistical properties based on field data in a Luvisol and simulate artificial water dynamics in this model soil based on Richards-equation. Within this model soil we define several hypothetical "Spatial TDR" clusters, that differ in the lateral spacing and the number of the probes, in the temporal resolution of the hypothetical measurements and in the assumed mea- surement accuracy. If the model soil approaches hydraulic equilibrium, the remaining soil moisture pattern will be dominated by the statistical properties of the porosity. In contrary the variability of the hydraulic conductivity will dominate the soil moisture patterns during infiltration events. The hypothetical Spatial TDR measurements within the

  7. How does spatial variability of climate affect catchment streamflow predictions?

    EPA Science Inventory

    Spatial variability of climate can negatively affect catchment streamflow predictions if it is not explicitly accounted for in hydrologic models. In this paper, we examine the changes in streamflow predictability when a hydrologic model is run with spatially variable (distribute...

  8. Environmental mapping based on spatial variability.

    PubMed

    Kovalevskaya, Nelley; Pavlov, Vladimir

    2002-01-01

    Environmental maps show the probable environmental states of different types of land use or development of landscape in a geographic context. Remotely sensed data are particularly efficient for environmental mapping in order to outline major environmental types. Multiple schemes of image classification used in environmental mapping are either traditionally statistical or heuristic. While the former methods do not take account of spatial variability in space and aerial data, the latter ones does not lend themselves to optimal solutions we present. Novel probabilistic models of piecewise-homogeneous images are used in environmental mapping to segment real images. The models consider both an image and a land cover map. Such a pair constitutes an example of a Markov random field specified by a joint Gibbs probability distribution of images and maps. Parameters of the model are estimated by using a stochastic approximation technique. Its convergence to the desired values is studied experimentally. Addition of spatial attributes appears to be necessary in most areas where the differences in spatial data between regions in the image occur. Experiments in generating the pairs of images and environmental maps and in segmenting the simulated as well as real images are discussed. PMID:12371162

  9. Spatial Variability in the Stratosphere of Uranus

    NASA Astrophysics Data System (ADS)

    Orton, Glenn; Trafton, Lawrence; Encrenaz, Therese; Lacy, John; Fletcher, Leigh; Sinclair, James; Moses, Julianne; Leyrat, Cedric; Pantin, Eric

    2015-04-01

    Observations of spatial variability in the atmosphere of Uranus have been limited to cloud properties and temperatures in the troposphere from a combination of spacecraft and ground-based observations. We report observations of the spatial distribution of (1) the stratospheric temperature field and (2) the distribution of stratospheric acetylene from ground-based mid-infrared observations using giant telescopes that resolve the planet spatially. (1) Temperatures in the stratosphere were derived from spectral scanning of the H2 rotational S(1) quadrupole using the TEXES spectrometer at the Gemini North observatory in 2007, near Uranus' equinox at high resolution (R=55,000). The H2 S(1) line was mapped by scanning the slit longitudinally across the entire disk of the planet. The observed radiances from the line center emerge primarily from the 0.1-0.3mbar pressure level. As expected for the 'thermally inverted' stratosphere, the planet is limb brightened at all latitudes, generally consistent with the predictions for the temperature structure derived from Spitzer IRS disk-averaged spectra (Orton et al. 2014 Icarus 243, 494). A cut through the central meridian shows a generally smooth variability, with the (IAU-defined) northern hemisphere emerging from winter darkness marginally brighter than the southern hemisphere, consistent with a smooth meridional gradient of temperatures. A cut across the equator reveals an ostensible central brightening, as well as equal brightening toward the limbs. (2) The distribution of C2H2 in the stratosphere was derived from images of thermal emission made in 2009 using the mid-infrared imager/spectrometers VISIR at the Very Large Telescope and T-ReCS at the Gemini South Observatory using a 13.04-μm moderate-band (NeII_2) filter. Because the continuum in this spectral region is so faint, the upwelling radiation is dominated by acetylene emission from roughly the same pressure level at the radiation from the H2 S(2) quadrupole line

  10. A new spatially scanning 2.7 µm laser hygrometer and new small-scale wind tunnel for direct analysis of the H2O boundary layer structure at single plant leaves

    NASA Astrophysics Data System (ADS)

    Wunderle, K.; Rascher, U.; Pieruschka, R.; Schurr, U.; Ebert, V.

    2015-01-01

    A new spatially scanning TDLAS in situ hygrometer based on a 2.7-µm DFB diode laser was constructed and used to analyse the water vapour concentration boundary layer structure at the surface of a single plant leaf. Using an absorption length of only 5.4 cm, the TDLAS hygrometer permits a H2O vapour concentration resolution of 31 ppmv. This corresponds to a normalized precision of 1.7 ppm m. In order to preserve and control the H2O boundary layer on an individual leaf and to study the boundary layer dependence on the wind speed to which the leaf might be exposed in nature, we also constructed a new, application specific, small-scale, wind tunnel for individual plant leaves. The rectangular, closed-loop tunnel has overall dimensions of 1.2 × 0.6 m and a measurement chamber dimension of 40 × 54 mm (H × W). It allows to generate a laminar flow with a precisely controlled wind speed at the plant leaf surface. Combining honeycombs and a miniaturized compression orifice, we could generate and control stable wind speeds from 0.1 to 0.9 m/s, and a highly laminar and homogeneous flow with an excellent relative spatial homogeneity of 0.969 ± 0.03. Combining the spectrometer and the wind tunnel, we analysed (for the first time) non-invasively the wind speed-dependent vertical structure of the H2O vapour distribution within the boundary layer of a single plant leaf. Using our time-lag-free data acquisition procedure for phase locked signal averaging, we achieved a temporal resolution of 0.2 s for an individual spatial point, while a complete vertical spatial scan at a spatial resolution of 0.18 mm took 77 s. The boundary layer thickness was found to decrease from 6.7 to 3.6 mm at increasing wind speeds of 0.1-0.9 m/s. According to our knowledge, this is the first experimental quantification of wind speed-dependent H2O vapour boundary layer concentration profiles of single plant leaves.

  11. Image restoration with spatially variable PSF

    NASA Astrophysics Data System (ADS)

    Ciliegi, Paolo; La Camera, Andrea; Schreiber, Laura; Bellazzini, Michele; Bertero, Mario; Boccacci, Patrizia; Diolaiti, Emiliano; Foppiani, Italo; Lombini, Matteo; Massari, Davide; Montegriffo, Paolo; Talia, Margherita

    2014-08-01

    We present a method for the restoration of astronomical images obtained with Adaptive Optics (AO) systems. In order to maximize the scientific return from AO data and, in general, from the data of the next generation telescopes, we developed a restoration method based on deconvolution for the de-blurring of images degraded by a spatially variable PSF. The deconvolution method is based on a partition of the image domain in partially overlapping sub-domains where the PSF can be assumed to be space invariant. The software, called Patch, is written in IDL language and is freely distributed to the community. Here we report a general description of the method and of its graphical interface. The potentiality of the Software Patch have been tested on two completely different astrophysical scenarios: a crowded stellar field and an extended galaxy. Despite the very conservative assumptions made on the Point Spread Function (assumed to be strongly variable across the field of view), we obtained good results in terms of image reconstruction both for the stellar (point-like) case and for the extended galaxy.

  12. Small Scale High Speed Turbomachinery

    NASA Technical Reports Server (NTRS)

    London, Adam P. (Inventor); Droppers, Lloyd J. (Inventor); Lehman, Matthew K. (Inventor); Mehra, Amitav (Inventor)

    2015-01-01

    A small scale, high speed turbomachine is described, as well as a process for manufacturing the turbomachine. The turbomachine is manufactured by diffusion bonding stacked sheets of metal foil, each of which has been pre-formed to correspond to a cross section of the turbomachine structure. The turbomachines include rotating elements as well as static structures. Using this process, turbomachines may be manufactured with rotating elements that have outer diameters of less than four inches in size, and/or blading heights of less than 0.1 inches. The rotating elements of the turbomachines are capable of rotating at speeds in excess of 150 feet per second. In addition, cooling features may be added internally to blading to facilitate cooling in high temperature operations.

  13. Crop growth and soil water spatial variability under a variable rate center pivot

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Precision agriculture has mostly emphasized variable-rate nutrients, seeding, and pesticide applications. More recently, variable-rate irrigation equipment has been developed to explore the potential for managing irrigation spatially. Managing irrigation spatially can enhance water conservation and ...

  14. A semi-urban case study of small scale variability of rainfall and run-off, with C- and X-band radars and the fully distributed hydrological model Multi-Hydro

    NASA Astrophysics Data System (ADS)

    Alves de Souza, Bianca; da Silva Rocha Paz, Igor; Gires, Auguste; Tchiguirinskaia, Ioulia; Schertzer, Daniel

    2016-04-01

    The complexity of urban hydrology results both from that of urban systems and the extreme rainfall variability. The latter can display strongly localised rain cells that can be extremely damaging when hitting vulnerable parts of urban systems. This paper investigates this complexity on a semi-urban sub-catchment - located in Massy (South of Paris, France) - of the Bievre river, which is known for its frequent flashfloods. Advanced geo-processing techniques were used to find the ideal pixel size for this 6.326km2 basin. C-band and X-band radar data are multifractally downscaled at various resolutions and input to the fully distributed hydrological model Multi-Hydro. The latter has been developed at Ecole des Ponts ParisTech. It integrates validated modules dealing with surface flow, saturated and unsaturated surface flow, and sewer flow. The C-band radar is located in Trappes, approx. 21km East of the catchment, is operated by Méteo-France and has a resolution of 1km x 1km x 5min. The X-band radar operated by Ecole des Ponts Paris Tech on its campus has a resolution of 125m x 125m x 3.4min. The performed multifractal downscaling enables both the generation of large ensemble realizations and easy change of resolution (e.g. down to 10 m in the present study). This in turn allows a detailed analysis of the impacts of small scale variability and the required resolution to obtain accurate simulations, therefore predictions. This will be shown on two rainy episodes over the chosen sub-catchment of the Bievre river.

  15. Spatial variability of the Black Sea surface temperature from high resolution modeling and satellite measurements

    NASA Astrophysics Data System (ADS)

    Mizyuk, Artem; Senderov, Maxim; Korotaev, Gennady

    2016-04-01

    Large number of numerical ocean models were implemented for the Black Sea basin during last two decades. They reproduce rather similar structure of synoptical variability of the circulation. Since 00-s numerical studies of the mesoscale structure are carried out using high performance computing (HPC). With the growing capacity of computing resources it is now possible to reconstruct the Black Sea currents with spatial resolution of several hundreds meters. However, how realistic these results can be? In the proposed study an attempt is made to understand which spatial scales are reproduced by ocean model in the Black Sea. Simulations are made using parallel version of NEMO (Nucleus for European Modelling of the Ocean). A two regional configurations with spatial resolutions 5 km and 2.5 km are described. Comparison of the SST from simulations with two spatial resolutions shows rather qualitative difference of the spatial structures. Results of high resolution simulation are compared also with satellite observations and observation-based products from Copernicus using spatial correlation and spectral analysis. Spatial scales of correlations functions for simulated and observed SST are rather close and differs much from satellite SST reanalysis. Evolution of spectral density for modelled SST and reanalysis showed agreed time periods of small scales intensification. Using of the spectral analysis for satellite measurements is complicated due to gaps. The research leading to this results has received funding from Russian Science Foundation (project № 15-17-20020)

  16. Models of Small-Scale Patchiness

    NASA Technical Reports Server (NTRS)

    McGillicuddy Dennis J., Jr.

    2001-01-01

    Patchiness is perhaps the most salient characteristic of plankton populations in the ocean. The scale of this heterogeneity spans many orders of magnitude in its spatial extent, ranging from planetary down to microscale. It has been argued that patchiness plays a fundamental role in the functioning of marine ecosystems, insofar as the mean conditions may not reflect the environment to which organisms are adapted. For example, the fact that some abundant predators cannot thrive on the mean concentration of their prey in the ocean implies that they are somehow capable of exploiting small-scale patches of prey whose concentrations are much larger than the mean. Understanding the nature of this patchiness is thus one of the major challenges of oceanographic ecology. Additional information is contained in the original extended abstract.

  17. Spatial Variability and Scaling of Infiltration on Undulating Agricultural Terrain

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This presentation focuses on surface water infiltration and soil physical properties affecting spatial soil water, nutrient, and plant estimation along with uncertainty and scaling associated with spatial variability. The field site in northeastern Colorado, USA comprises undulating agricultural te...

  18. A small scale honey dehydrator.

    PubMed

    Gill, R S; Hans, V S; Singh, Sukhmeet; Pal Singh, Parm; Dhaliwal, S S

    2015-10-01

    A small scale honey dehydrator has been designed, developed, and tested to reduce moisture content of honey below 17 %. Experiments have been conducted for honey dehydration by using drying air at ambient temperature, 30 and 40 °C and water at 35, 40 and 45 °C. In this dehydrator, hot water has been circulated in a water jacket around the honey container to heat honey. The heated honey has been pumped through a sieve to form honey streams through which drying air passes for moisture removal. The honey streams help in increasing the exposed surface area of honey in contact with drying air, thus resulting in faster dehydration of honey. The maximum drying rate per square meter area of honey exposed to drying air was found to be 197.0 g/h-m(2) corresponding to the drying air and water temperature of 40 and 45 °C respectively whereas it was found to be minimum (74.8 g/h-m(2)) corresponding to the drying air at ambient temperature (8-17 °C) and water at 35 °C. The energy cost of honey moisture content reduction from 25.2 to 16.4 % was Rs. 6.20 to Rs. 17.36 (US $ 0.10 to US $ 0.28 (One US $ = 62.00 Indian Rupee on February, 2014) per kilogram of honey. PMID:26396418

  19. Small-scale eruptive filaments on the quiet sun

    NASA Technical Reports Server (NTRS)

    Hermans, Linda M.; Martin, Sara F.

    1986-01-01

    A study of a little known class of eruptive events on the quiet sun was conducted. All of 61 small-scale eruptive filamentary structures were identified in a systematic survey of 32 days of H alpha time-lapse films of the quiet sun acquired at Big Bear Solar Observatory. When fully developed, these structures have an average length of 15 arc seconds before eruption. They appear to be the small-scale analog of large-scale eruptive filaments observed against the disk. At the observed rate of 1.9 small-scale eruptive features per field of view per average 7.0 hour day, the rate of occurence of these events on the sun were estimated to be greater than 600 per 24 hour day.. The average duration of the eruptive phase was 26 minutes while the average lifetime from formation through eruption was 70 minutes. A majority of the small-scale filamentary sturctures were spatially related to cancelling magnetic features in line-of-sight photospheric magnetograms. Similar to large-scale filaments, the small-scale filamentary structures sometimes divided opposite polarity cancelling fragments but often had one or both ends terminating at a cancellation site. Their high numbers appear to reflect the much greater flux on the quiet sun. From their characteristics, evolution, and relationship to photospheric magnetic flux, it was concluded that the structures described are small-scale eruptive filaments and are a subset of all filaments.

  20. Practical small-scale explosive seam welding

    NASA Technical Reports Server (NTRS)

    Bement, L. J.

    1983-01-01

    A small-scale explosive seam welding process has been developed that can significantly contribute to remote metal joining operations under hazardous or inaccessible conditions, such as nuclear reactor repair and assembly of structure in space. This paper describes this explosive seam welding process in terms of joining principles, variables, types of joints created, capabilities, and applications. Very small quantities of explosive in a ribbon configuration are used to create narrow (less than 0.5 inch), long-length, uniform, hermetically sealed joints that exhibit parent metal properties in a wide variety of metals, alloys, and combinations. The practicality of this process has been demonstrated by its current acceptance, as well as its capabilities that are superior in many applications to the universally accepted joining processes, such as mechanical fasteners, fusion and resistance welding, and adhesives.

  1. Mathematical Modeling of spatial disease variables by Spatial Fuzzy Logic for Spatial Decision Support Systems

    NASA Astrophysics Data System (ADS)

    Platz, M.; Rapp, J.; Groessler, M.; Niehaus, E.; Babu, A.; Soman, B.

    2014-11-01

    A Spatial Decision Support System (SDSS) provides support for decision makers and should not be viewed as replacing human intelligence with machines. Therefore it is reasonable that decision makers are able to use a feature to analyze the provided spatial decision support in detail to crosscheck the digital support of the SDSS with their own expertise. Spatial decision support is based on risk and resource maps in a Geographic Information System (GIS) with relevant layers e.g. environmental, health and socio-economic data. Spatial fuzzy logic allows the representation of spatial properties with a value of truth in the range between 0 and 1. Decision makers can refer to the visualization of the spatial truth of single risk variables of a disease. Spatial fuzzy logic rules that support the allocation of limited resources according to risk can be evaluated with measure theory on topological spaces, which allows to visualize the applicability of this rules as well in a map. Our paper is based on the concept of a spatial fuzzy logic on topological spaces that contributes to the development of an adaptive Early Warning And Response System (EWARS) providing decision support for the current or future spatial distribution of a disease. It supports the decision maker in testing interventions based on available resources and apply risk mitigation strategies and provide guidance tailored to the geo-location of the user via mobile devices. The software component of the system would be based on open source software and the software developed during this project will also be in the open source domain, so that an open community can build on the results and tailor further work to regional or international requirements and constraints. A freely available EWARS Spatial Fuzzy Logic Demo was developed wich enables a user to visualize risk and resource maps based on individual data in several data formats.

  2. Continuous-variable quantum computation with spatial degrees of freedom of photons

    SciTech Connect

    Tasca, D. S.; Gomes, R. M.; Toscano, F.; Souto Ribeiro, P. H.; Walborn, S. P.

    2011-05-15

    We discuss the use of the transverse spatial degrees of freedom of photons propagating in the paraxial approximation for continuous-variable information processing. Given the wide variety of linear optical devices available, a diverse range of operations can be performed on the spatial degrees of freedom of single photons. Here we show how to implement a set of continuous quantum logic gates which allow for universal quantum computation. In contrast with the usual quadratures of the electromagnetic field, the entire set of single-photon gates for spatial degrees of freedom does not require optical nonlinearity and, in principle, can be performed with a single device: the spatial light modulator. Nevertheless, nonlinear optical processes, such as four-wave mixing, are needed in the implementation of two-photon gates. The efficiency of these gates is at present very low; however, small-scale investigations of continuous-variable quantum computation are within the reach of current technology. In this regard, we show how novel cluster states for one-way quantum computing can be produced using spontaneous parametric down-conversion.

  3. Revealing Small-Scale Details

    NASA Astrophysics Data System (ADS)

    Crawford, Ken

    Astrophotographers face amazing challenges in their pursuit of acquiring high quality data and then turn that data into beautiful images that viewers admire. We carefully set up our imaging systems with amazing precision so each exposure contains well focused sharp sub frames. For every exposure there exist a myriad of variables that can work against us to potentially degrade the details of the celestial objects we record. Some of these variables are within our control and some are not. Even the variables beyond our control can often be compensated for by processing adjustments for maximizing the potential of our images. My goal is to share some of the methods I have found useful in recovering those elements that bring clarity to our pictures.

  4. How does spatial variability of climate affect catchment streamflow predictions?

    NASA Astrophysics Data System (ADS)

    Patil, Sopan D.; Wigington, Parker J.; Leibowitz, Scott G.; Sproles, Eric A.; Comeleo, Randy L.

    2014-09-01

    Spatial variability of climate can negatively affect catchment streamflow predictions if it is not explicitly accounted for in hydrologic models. In this paper, we examine the changes in streamflow predictability when a hydrologic model is run with spatially variable (distributed) meteorological inputs instead of spatially uniform (lumped) meteorological inputs. Both lumped and distributed versions of the EXP-HYDRO model are implemented at 41 meso-scale (500-5000 km2) catchments in the Pacific Northwest region of USA. We use two complementary metrics of long-term spatial climate variability, moisture homogeneity index (IM) and temperature variability index (ITV), to analyze the performance improvement with distributed model. Results show that the distributed model performs better than the lumped model in 38 out of 41 catchments, and noticeably better (>10% improvement) in 13 catchments. Furthermore, spatial variability of moisture distribution alone is insufficient to explain the observed patterns of model performance improvement. For catchments with low moisture homogeneity (IM < 80%), IM is a better predictor of model performance improvement than ITV; whereas for catchments with high moisture homogeneity (IM > 80%), ITV is a better predictor of performance improvement than IM. Based on the results, we conclude that: (1) catchments that have low homogeneity of moisture distribution are the obvious candidates for using spatially distributed meteorological inputs, and (2) catchments with a homogeneous moisture distribution benefit from spatially distributed meteorological inputs if they also have high spatial variability of precipitation phase (rain vs. snow).

  5. Small scale structure on cosmic strings

    NASA Technical Reports Server (NTRS)

    Albrecht, Andreas

    1989-01-01

    The current understanding of cosmic string evolution is discussed, and the focus placed on the question of small scale structure on strings, where most of the disagreements lie. A physical picture designed to put the role of the small scale structure into more intuitive terms is presented. In this picture it can be seen how the small scale structure can feed back in a major way on the overall scaling solution. It is also argued that it is easy for small scale numerical errors to feed back in just such a way. The intuitive discussion presented here may form the basis for an analytic treatment of the small scale structure, which argued in any case would be extremely valuable in filling the gaps in the present understanding of cosmic string evolution.

  6. A mobile system for quantifying the spatial variability of the surface energy balance: design and application

    NASA Astrophysics Data System (ADS)

    Wohlfahrt, Georg; Tasser, Erich

    2015-05-01

    We present a mobile device for the quantification of the small-scale (a few square meters) spatial variability in the surface energy balance components and several auxiliary variables of short-statured (<1 m) canopies. The key element of the mobile device is a handheld four-component net radiometer for the quantification of net radiation, albedo and infrared surface temperature, which is complemented with measurements of air temperature, wind speed, soil temperature and soil water content. Data are acquired by a battery-powered data logger, which is mounted on a backpack together with the auxiliary sensors. The proposed device was developed to bridge between the spatial scales of satellite/airborne remote sensing and fixed, stationary tower-based measurements with an emphasis on micrometeorological, catchment hydrological and landscape-ecological research questions. The potential of the new device is demonstrated through four selected case studies, which cover the issues of net radiation heterogeneity within the footprint of eddy covariance flux measurements due to (1) land use and (2) slope and aspect of the underlying surface, (3) controls on landscape-scale variability in soil temperature and albedo and (4) the estimation of evapotranspiration based exclusively on measurements with the mobile device.

  7. A mobile system for quantifying the spatial variability of the surface energy balance: design and application

    NASA Astrophysics Data System (ADS)

    Tasser, Erich; Wohlfahrt, Georg

    2014-05-01

    We present a mobile device for the quantification of the small-scale spatial variability in the surface energy balance components and several auxiliary variables of short-statured canopies. The key element of the mobile device is a hand-held four-component net radiometer for the quantification of net radiation, albedo and infrared surface temperature, which is complemented with measurements of air temperature, wind speed, soil temperature and soil water content. Data are acquired by a battery-powered data logger, which is mounted on a backpack together with the auxiliary sensors. The proposed device was developed to bridge between the spatial scales of satellite/airborne remote sensing and fixed, stationary tower-based measurements with an emphasis on micrometeorological, catchment hydrological and landscape-ecological research questions. The potential of the new device is demonstrated through four selected case studies, which cover the issues of net radiation heterogeneity within the footprint of eddy covariance flux measurements due to (i) land use and (ii) slope and aspect of the underlying surface, (iii) controls on landscape-scale variability in soil temperature and albedo, and (iv) the estimation of evapotranspiration based exclusively on measurements with the mobile device.

  8. A mobile system for quantifying the spatial variability of the surface energy balance: design and application.

    PubMed

    Wohlfahrt, Georg; Tasser, Erich

    2015-05-01

    We present a mobile device for the quantification of the small-scale (a few square meters) spatial variability in the surface energy balance components and several auxiliary variables of short-statured (<1 m) canopies. The key element of the mobile device is a handheld four-component net radiometer for the quantification of net radiation, albedo and infrared surface temperature, which is complemented with measurements of air temperature, wind speed, soil temperature and soil water content. Data are acquired by a battery-powered data logger, which is mounted on a backpack together with the auxiliary sensors. The proposed device was developed to bridge between the spatial scales of satellite/airborne remote sensing and fixed, stationary tower-based measurements with an emphasis on micrometeorological, catchment hydrological and landscape-ecological research questions. The potential of the new device is demonstrated through four selected case studies, which cover the issues of net radiation heterogeneity within the footprint of eddy covariance flux measurements due to (1) land use and (2) slope and aspect of the underlying surface, (3) controls on landscape-scale variability in soil temperature and albedo and (4) the estimation of evapotranspiration based exclusively on measurements with the mobile device. PMID:25063050

  9. Spatial Variability of CCN Sized Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Asmi, A.; Väänänen, R.

    2014-12-01

    The computational limitations restrict the grid size used in GCM models, and for many cloud types they are too large when compared to the scale of the cloud formation processes. Several parameterizations for e.g. convective cloud formation exist, but information on spatial subgrid variation of the cloud condensation nuclei (CCNs) sized aerosol concentration is not known. We quantify this variation as a function of the spatial scale by using datasets from airborne aerosol measurement campaigns around the world including EUCAARI LONGREX, ATAR, INCA, INDOEX, CLAIRE, PEGASOS and several regional airborne campaigns in Finland. The typical shapes of the distributions are analyzed. When possible, we use information obtained by CCN counters. In some other cases, we use particle size distribution measured by for example SMPS to get approximated CCN concentration. Other instruments used include optical particle counters or condensational particle counters. When using the GCM models, the CCN concentration used for each the grid-box is often considered to be either flat, or as an arithmetic mean of the concentration inside the grid-box. However, the aircraft data shows that the concentration values are often lognormal distributed. This, combined with the subgrid variations in the land use and atmospheric properties, might cause that the aerosol-cloud interactions calculated by using mean values to vary significantly from the true effects both temporary and spatially. This, in turn, can cause non-linear bias into the GCMs. We calculate the CCN aerosol concentration distribution as a function of different spatial scales. The measurements allow us to study the variation of these distributions within from hundreds of meters up to hundreds of kilometers. This is used to quantify the potential error when mean values are used in GCMs.

  10. Hall-magnetohydrodynamic small-scale dynamos.

    PubMed

    Gómez, Daniel O; Mininni, Pablo D; Dmitruk, Pablo

    2010-09-01

    Magnetic field generation by dynamo action is often studied within the theoretical framework of magnetohydrodynamics (MHD). However, for sufficiently diffuse media, the Hall effect may become non-negligible. We present results from three-dimensional simulations of the Hall-MHD equations subjected to random nonhelical forcing. We study the role of the Hall effect in the dynamo efficiency for different values of the Hall parameter. For small values of the Hall parameter, the small-scale dynamo is more efficient, displaying faster growth and saturating at larger amplitudes of the magnetic field. For larger values of the Hall parameter, saturation of the magnetic field is reached at smaller amplitudes than in the MHD case. We also study energy transfer rates among spatial scales and show that the Hall effect produces a reduction of the direct energy cascade at scales larger than the Hall scale, therefore leading to smaller energy dissipation rates. Finally, we present results stemming from simulations at large magnetic Prandtl numbers, which is the relevant regime in the hot and diffuse interstellar medium. In the range of magnetic Prandtl numbers considered, the Hall effect moves the peak of the magnetic energy spectrum as well as other relevant magnetic length scales toward the Hall scale. PMID:21230195

  11. Spatial scales of optical variability in the coastal ocean: Implications for remote sensing and in situ sampling

    NASA Astrophysics Data System (ADS)

    Moses, Wesley J.; Ackleson, Steven G.; Hair, Johnathan W.; Hostetler, Chris A.; Miller, W. David

    2016-06-01

    Use of ocean color remote sensing to understand the effects of environmental changes and anthropogenic activities on estuarine and coastal waters requires the capability to measure and track optically detectable complex biogeochemical processes. An important remote sensor design consideration is the minimum spatial resolution required to resolve key ocean features of physical and biological significance. The spatial scale of variability in optical properties of coastal waters has been investigated using continuous, along-track measurements collected using instruments deployed from ships, aircraft, and satellites. We defined the average coefficient of variance, CV¯a, within an image pixel as the primary statistical measure of subpixel variability and investigated how CV¯a changes as a function of the Ground Sampling Distance (GSD). In general, dCV¯a/dGSD is positive, indicating that the subpixel variability increases with GSD. The relationship between CV¯a and GSD is generally nonlinear and the greatest rate of change occurs at small spatial scales. Points of distinct transition in the relationship between CV¯a and GSD are evident between 75 and 600 m, varying depending on the location and the optical parameter, and representing the GSD above which most of the spatial variability due to small-scale features is subsumed within a pixel. At GSDs greater than the transition point, most of the small-scale variability occurs at subpixel scales and, therefore, cannot be resolved. On average, the transition GSD is around 200 m. The results have application in both sensor design and in situ sampling strategy in support of coastal remote sensing operations.

  12. Modeling Bioenergy Feedstock Supply: Impacts of Temporal and Spatial Variability

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A theoretical model is constructed illustrating how transportation costs and spatial and temporal variability in feedstock production influence farm production practices and resulting impacts on bioenergy feedstock supply and the environment. The model is constructed for a bioenergy producer minimiz...

  13. Method and system for small scale pumping

    DOEpatents

    Insepov, Zeke; Hassanein, Ahmed

    2010-01-26

    The present invention relates generally to the field of small scale pumping and, more specifically, to a method and system for very small scale pumping media through microtubes. One preferred embodiment of the invention generally comprises: method for small scale pumping, comprising the following steps: providing one or more media; providing one or more microtubes, the one or more tubes having a first end and a second end, wherein said first end of one or more tubes is in contact with the media; and creating surface waves on the tubes, wherein at least a portion of the media is pumped through the tube.

  14. Small scale bipolar nickel-hydrogen testing

    NASA Technical Reports Server (NTRS)

    Manzo, Michelle A.

    1988-01-01

    Bipolar nickel-hydrogen batteries, ranging in capacity from 6 to 40 A-hr, have been tested at the NASA Lewis Research Center over the past six years. Small scale tests of 1 A-hr nickel-hydrogen stacks have been initiated as a means of screening design and component variations for bipolar nickel-hydrogen cells and batteries. Four small-scale batteries have been built and tested. Characterization and limited cycle testing were performed to establish the validity of test results in the scaled down hardware. The results show characterization test results to be valid. LEO test results in the small scale hardware have limited value.

  15. Small-scale spatial and temporal reproductive variability of the brown macroalga Sargassum thunbergii in contrasting habitats: A study on the island of Xiaoheishan, Changdao Archipelago, China

    NASA Astrophysics Data System (ADS)

    Yu, Yongqiang; Zhang, Quansheng; Lu, Zhicheng; Tang, Yongzheng; Zhang, Shubao; Chu, Shaohua

    2012-10-01

    A study of the reproductive pattern of Sargassum thunbergii, which is distributed widely around the island of Xiaoheishan (Changdao Archipelago, China), shows that it exhibits a flexibility to adapt to contrasting habitats. Populations of S. thunbergii from two depths at nine field sites exposed to increasing degrees of wave action were studied to determine their spatio-temporal variations in reproductive pattern. The start of the reproductive period was significantly delayed with increasing geographical latitude but independent of depth and wave exposure, and seawater temperature was found to be a significant controlling factor for maturation. In contrast with reproductive onset, two-way ANCOVA showed that there were significant effects of both depth and wave exposure on the peak and end point of the reproductive period. The latter were significantly delayed in the semi-exposed deep-water habitats compared to sheltered shallow-water habitats. The shortest duration of the reproductive period was recorded in the wave-exposed shallow-water habitats, while the longest duration was in the semi-exposed deep-water habitats. In addition, reproductive allocation (RA) in the studied populations showed a similar and significant temporal variation during reproduction, and RA increased as time progressed, followed by a rapid decrease in late summer. Wave exposure as well as depth also influenced significantly the RA whereby thalli from exposed and semi-exposed deep-water habitats allocated significantly more biomass to the production of receptacles than did thalli from sheltered shallow-water habitats.

  16. Small scale structure on cosmic strings

    SciTech Connect

    Albrecht, A.

    1989-10-30

    I discuss our current understanding of cosmic string evolution, and focus on the question of small scale structure on strings, where most of the disagreements lie. I present a physical picture designed to put the role of the small scale structure into more intuitive terms. In this picture one can see how the small scale structure can feed back in a major way on the overall scaling solution. I also argue that it is easy for small scale numerical errors to feed back in just such a way. The intuitive discussion presented here may form the basis for an analytic treatment of the small structure, which I argue in any case would be extremely valuable in filling the gaps in our resent understanding of cosmic string evolution. 24 refs., 8 figs.

  17. Spatial and Temporal Variability of Macronutrients in a Lime-amended Acid Paddy Field

    NASA Astrophysics Data System (ADS)

    Vidal Vázquez, E.; Morales, L. A.; Paz González, A.

    2012-04-01

    tillering could be also attributed to lime addition, but a negative effect of liming on P availability was observed during flowering. Mehlich I extractable K was in general low to very low and decreased from sowing to flowering, irrespective of lime treatment. Semivariogram analysis showed a rather strong spatial dependence of NH4+, P and K concentrations and this all over the three study periods and for the three lime treatments. Empirical semivariograms could be adjusted quite well by a nugget component (C0) plus a spatial structure (C1), which was described by spherical or exponential models with a correlation range between 40 and 85 m. Geostatistical analysis provided insight into possible processes responsible of the observed spatial variability patterns within the rice soil. Kriging was useful in mapping macronutrient variability allowing identifying microrregions with high or low values of the target soil properties clearly showing the presence of small scale variability for the study soil attributes within each liming treatment and during each of the three sampling dates. Also the position of patches with maxima and minima values changed between successive sampling dates illustrating the lack of temporal stability of the pattern of spatial distribution for the study soil attributes. Results illustrate the potential for applying the principles of precision agriculture to control spatiotemporal variability in rice fields.

  18. Enhancing metrology by combining spatial variability and global inference

    NASA Astrophysics Data System (ADS)

    Spanos, Costas J.; Baek, Jae Yeon

    2013-04-01

    Recently, there has been significant interest in so-called Hybrid or Holistic Metrology, the practice of combining measurements from multiple sources in order to improve the estimation of one or more critical parameters. There also has been significant research in capturing and modeling the hierarchical spatial variability of CDs at the die, wafer, and lot level. However, the information inherent in spatial variability models has not been used towards improving the accuracy/precision of CD estimates. In this paper, we review the current trends in Hybrid Metrology and Spatial Variability Modeling, and provide a simple example based on the work of Zhang et al.1 that illustrates how we can incorporate spatial information for improved measurement estimates.

  19. Temporal variability in aboveground plant biomass decreases as spatial variability increases.

    PubMed

    McGranahan, Devan Allen; Hovick, Torre J; Elmore, R Dwayne; Engle, David M; Fuhlendorf, Samuel D; Winter, Stephen L; Miller, James R; Debinski, Diane M

    2016-03-01

    Ecological theory predicts that diversity decreases variability in ecosystem function. We predict that, at the landscape scale, spatial variability created by a mosaic of contrasting patches that differ in time since disturbance will decrease temporal variability in aboveground plant biomass. Using data from a multi-year study of seven grazed tallgrass prairie landscapes, each experimentally managed for one to eight patches, we show that increased spatial variability driven by spatially patchy fire and herbivory reduces temporal variability in aboveground plant biomass. This pattern is associated with statistical evidence for the portfolio effect and a positive relationship between temporal variability and functional group synchrony as predicted by metacommunity variability theory. As disturbance from fire and grazing interact to create a shifting mosaic of spatially heterogeneous patches within a landscape, temporal variability in aboveground plant biomass can be dampened. These results suggest that spatially heterogeneous disturbance regimes contribute to a portfolio of ecosystem functions provided by biodiversity, including wildlife habitat, fuel, and forage. We discuss how spatial patterns of disturbance drive variability within and among patches. PMID:27197382

  20. Combining snowpack modeling and terrestrial laser scanner observations improves the simulation of small scale snow dynamics

    NASA Astrophysics Data System (ADS)

    Revuelto, Jesús; Vionnet, Vincent; López-Moreno, Juan-Ignacio; Lafaysse, Matthieu; Morin, Samuel

    2016-02-01

    Accurately determining the snowpack distribution in mountain areas is complex because of the difficulty of establishing over large areas the spatial distribution of all variables that define the state of the snowpack at any particular time. In this study we used distributed snowpack simulations that were corrected throughout the snow season using snow depth distributions measured using a terrestrial laser scanner (TLS). This enabled us to obtain a more realistic view of the small scale spatial evolution of the mass and depth of the snowpack. Several TLS snow depth data acquisitions were made during the 2012, 2013 and 2014 snow seasons in a small catchment (55 ha) located in the central Spanish Pyrenees. The Crocus snowpack model was used to simulate the snowpack evolution on a 5-m grid, based on downscaled meteorological variables obtained using SAFRAN reanalysis. The simulation was stopped when a snow depth distribution map measured using the TLS was available, and the modeled snow depth distribution was adjusted to match the observed snow depth. The snow simulation was then restarted and run until the next TLS acquisition was available. Prior to matching the simulation and observational data, both snowpack distributions were compared. The results for the three snow seasons showed an improvement in the snowpack simulation, especially with respect to simulating the influence of small scale topographic effects on the observed snowpack distribution, and also the timing of snow melt dynamics.

  1. The Impacts of Water Quality and Food Availability on Children's Health in West Africa: A Spatial Analysis Using Remotely Sensed Data and Small-Scale Water Quality Data and Country-level Health Data

    NASA Astrophysics Data System (ADS)

    Frederick, L.; Grace, K.; Lloyd, B.

    2015-12-01

    As the global climate changes and the populations of many African countries grow, ensuring clean drinking water and food has become a pressing concern. Because of their vulnerability to malnutrition and food insecurity, children face the greatest risk for adverse health outcomes related to climate change. Vulnerability, however, is highly variable, with some children in food insecure communities showing healthy growth, while some children in food secure communities show signs of malnutrition. In West Africa, Burkina Faso faces high levels of child malnutrition, loses to farmland and a large share of the population have no access to clean water. Because the overwhelming majority of children rely on locally grown, rainfed agriculture and well/surface water, the combined impact of climate change and population growth decreases water availability and farmland per person. However, there is notable community and individual variation in malnutrition levels suggesting that there are important coping strategies that vulnerable families may use to secure their children's health. No spatially relevant analysis of water and food insecurity and children's health exists for Burkina Faso. The goal of this research is to identify and quantify the combined and inter-related impact of unsafe drinking water and community-level food availability on the physical health outcomes of Burkinabe children under five years of age. To accomplish this goal we rely on a publically available highly detailed, geo-referenced data set (Demographic and Health Survey (DHS)) to provide information on measures of childhood malnutrition and details on parental characteristics related to children's health. Information on water source (covered/uncovered well, piped water, etc.) and water quality (measures of arsenic and pollution) comes from DHS along with a recently collected geo-referenced US Agency for International Development (USAID) data set. Critical information on food production, environmental

  2. The Impacts of Water Quality and Food Availability on Children's Health in West Africa: A Spatial Analysis Using Remotely Sensed Data and Small-Scale Water Quality Data and Country-level Health Data

    NASA Astrophysics Data System (ADS)

    Frederick, L.; Grace, K.; Lloyd, B.

    2014-12-01

    As the global climate changes and the populations of many African countries grow, ensuring clean drinking water and food has become a pressing concern. Because of their vulnerability to malnutrition and food insecurity, children face the greatest risk for adverse health outcomes related to climate change. Vulnerability, however, is highly variable, with some children in food insecure communities showing healthy growth, while some children in food secure communities show signs of malnutrition. In West Africa, Burkina Faso faces high levels of child malnutrition, loses to farmland and a large share of the population have no access to clean water. Because the overwhelming majority of children rely on locally grown, rainfed agriculture and well/surface water, the combined impact of climate change and population growth decreases water availability and farmland per person. However, there is notable community and individual variation in malnutrition levels suggesting that there are important coping strategies that vulnerable families may use to secure their children's health. No spatially relevant analysis of water and food insecurity and children's health exists for Burkina Faso. The goal of this research is to identify and quantify the combined and inter-related impact of unsafe drinking water and community-level food availability on the physical health outcomes of Burkinabe children under five years of age. To accomplish this goal we rely on a publically available highly detailed, geo-referenced data set (Demographic and Health Survey (DHS)) to provide information on measures of childhood malnutrition and details on parental characteristics related to children's health. Information on water source (covered/uncovered well, piped water, etc.) and water quality (measures of arsenic and pollution) comes from DHS along with a recently collected geo-referenced US Agency for International Development (USAID) data set. Critical information on food production, environmental

  3. Characterization of the spatial variability of channel morphology

    USGS Publications Warehouse

    Moody, J.A.; Troutman, B.M.

    2002-01-01

    The spatial variability of two fundamental morphological variables is investigated for rivers having a wide range of discharge (five orders of magnitude). The variables, water-surface width and average depth, were measured at 58 to 888 equally spaced cross-sections in channel links (river reaches between major tributaries). These measurements provide data to characterize the two-dimensional structure of a channel link which is the fundamental unit of a channel network. The morphological variables have nearly log-normal probability distributions. A general relation was determined which relates the means of the log-transformed variables to the logarithm of discharge similar to previously published downstream hydraulic geometry relations. The spatial variability of the variables is described by two properties: (1) the coefficient of variation which was nearly constant (0.13-0.42) over a wide range of discharge; and (2) the integral length scale in the downstream direction which was approximately equal to one to two mean channel widths. The joint probability distribution of the morphological variables in the downstream direction was modelled as a first-order, bivariate autoregressive process. This model accounted for up to 76 per cent of the total variance. The two-dimensional morphological variables can be scaled such that the channel width-depth process is independent of discharge. The scaling properties will be valuable to modellers of both basin and channel dynamics. Published in 2002 John Wiley and Sons, Ltd.

  4. Small-scale physics of the ocean

    NASA Technical Reports Server (NTRS)

    Caldwell, D. R.

    1983-01-01

    Progress in research on the small-scale physics of the ocean is reviewed. The contribution of such research to the understanding of the large scales is addressed and compared for various depth ranges of the ocean. The traditional framework for discussing small-scale measurements and turbulence is outlined, and recent research in the area is reviewed, citing references. Evidence for the existence of salt fingering in oceanic mixing is discussed. Factors that might inhibit the growth of salt fingers are assessed, and the influence of differences between laboratory tank and ocean in studying the fingers is discussed. The role of salt fingers in creating intrusions is examined. Instruments and methods used to measure the smallest scales at which there is appreciable variation and the stability of the patch of ocean in which the small-scale motions take place are considered.

  5. Geologic utility of small-scale airphotos

    NASA Technical Reports Server (NTRS)

    Clark, M. M.

    1969-01-01

    The geologic value of small scale airphotos is emphasized by describing the application of high altitude oblique and 1:120,000 to 1:145,000 scale vertical airphotos to several geologic problems in California. These examples show that small-scale airphotos can be of use to geologists in the following ways: (1) high altitude, high oblique airphotos show vast areas in one view; and (2) vertical airphotos offer the most efficient method of discovering the major topographic features and structural and lithologic characteristics of terrain.

  6. Spatial and temporal variability of chlorophyll in Bay of Bengal.

    NASA Astrophysics Data System (ADS)

    Jutla, A.; Akanda, S.; Islam, S.

    2009-04-01

    The Bay of Bengal (BoB) receives approximately 628 km3/ year of freshwater discharge from the Ganges and Brahmaputra rivers. Freshwater discharge from rivers increases the nutrient load and thereby enhances phytoplankton production in the BoB. Cholera, an infectious water-borne disease caused by bacterium Vibrio cholerae, remains endemic in the BoB region. Phytoplankton provides favorable environment for survival of cholera bacteria. Therefore, for development of any predictive model for cholera, it is important to quantify the spatial and temporal variability of phytoplankton in the BoB. Satellite remote sensing is the most effective way to quantify this variability over a range of space and time scales. Using ten years (1998-2007) of daily, weekly and monthly SeaWiFs chlorophyll, a surrogate variable for measuring phytoplankton, imagery we explore the spatial pattern and dominant temporal variability of chlorophyll over the BoB region. We find that chlorophyll in the coastal waters has more variability, both in temporal and spatial scales, than the offshore waters. Mechanism of production and space-time variability of coastal chlorophyll is different from those of offshore chlorophyll. While coastal chlorophyll is dominated by influx of terrestrial nutrients through river discharge, chlorophyll in the offshore region is primarily controlled by oceanic processes. We will also explore issues related to dominant space and time scales of chlorophyll variations in the entire bay.

  7. SMALL SCALE ETHANOL DRYING - PHASE II

    EPA Science Inventory

    This program exceeded all key milestones. Using cellulose Waste, CMS demonstrated novel ethanol drying membranes via small scale dephlegmation process that yields fuel grade ethanol (FGE) at a lower cost than large switch grass ethanol plants. This success yields positive valu...

  8. IAPSA 2 small-scale system specification

    NASA Technical Reports Server (NTRS)

    Cohen, Gerald C.; Torkelson, Thomas C.

    1990-01-01

    The details of a hardware implementation of a representative small scale flight critical system is described using Advanced Information Processing System (AIPS) building block components and simulated sensor/actuator interfaces. The system was used to study application performance and reliability issues during both normal and faulted operation.

  9. SMALL SCALE BIOMASS FUELED GAS TURBINE ENGINE

    EPA Science Inventory

    A new generation of small scale (less than 20 MWe) biomass fueled, power plants are being developed based on a gas turbine (Brayton cycle) prime mover. These power plants are expected to increase the efficiency and lower the cost of generating power from fuels such as wood. The n...

  10. Variability of Soil Temperature: A Spatial and Temporal Analysis.

    ERIC Educational Resources Information Center

    Walsh, Stephen J.; And Others

    1991-01-01

    Discusses an analysis of the relationship of soil temperatures at 3 depths to various climatic variables along a 200-kilometer transect in west-central Oklahoma. Reports that temperature readings increased from east to west. Concludes that temperature variations were explained by a combination of spatial, temporal, and biophysical factors. (SG)

  11. Spatial variability of water use efficiency in China's terrestrial ecosystems

    NASA Astrophysics Data System (ADS)

    Zhu, Xian-Jin; Yu, Gui-Rui; Wang, Qiu-Feng; Hu, Zhong-Min; Zheng, Han; Li, Sheng-Gong; Sun, Xiao-Min; Zhang, Yi-Ping; Yan, Jun-Hua; Wang, Hui-Min; Zhao, Feng-Hua; Zhang, Jun-Hui; Shi, Pei-Li; Li, Ying-Nian; Zhao, Liang; Zhang, Fa-Wei; Hao, Yan-Bin

    2015-06-01

    Water use efficiency (WUE) reflects the coupling of carbon and water cycles. Analyzing the spatial variability of WUE can improve our understanding on the interaction between carbon and water cycles at a large scale, which also provides a basis for improving the regional carbon budget assessment. Based on China's eddy covariance measurements, we examined the spatial variation of China's WUE and its affecting factors. WUE showed a decreasing trend with the increasing altitude, which was the result of ecosystem type distribution resulting from the climatic gradient. After fully considering the vertical variation of WUE, we found that not only mean annual air temperature (MAT), mean annual precipitation (MAP), and mean leaf area index (MLAI) but also mean annual total photosynthesis active radiation (MAR) affected the spatial variation of WUE. With the increasing MAT, MAP, and MLAI, WUE increased significantly but the increasing MAR decreased WUE. The spatial variation of WUE could be directly depicted by MLAI and altitude, the equation including which explained 65% of the spatial variation of WUE. The effects of MAT and MAP on the spatial variation of WUE may be achieved through altering MLAI, while the mechanism underlying the effect of MAR on the spatial variation of WUE was still unclear, which should be the subject of future investigations. This study reveals the vertical variation of WUE and provides a new approach to generate the spatial variation in WUE, which will benefit the regional carbon budget assessment.

  12. Impacts of rainfall spatial variability on hydrogeological response

    NASA Astrophysics Data System (ADS)

    Sapriza-Azuri, Gonzalo; Jódar, Jorge; Navarro, Vicente; Slooten, Luit Jan; Carrera, Jesús; Gupta, Hoshin V.

    2015-02-01

    There is currently no general consensus on how the spatial variability of rainfall impacts and propagates through complex hydrogeological systems. Most studies to date have focused on the effects of rainfall spatial variability (RSV) on river discharge, while paying little attention to other important aspects of system response. Here, we study the impacts of RSV on several responses of a hydrological model of an overexploited system. To this end, we drive a spatially distributed hydrogeological model for the semiarid Upper Guadiana basin in central Spain with stochastic daily rainfall fields defined at three different spatial resolutions (fine → 2.5 km × 2.5 km, medium → 50 km × 50 km, large → lumped). This enables us to investigate how (i) RSV at different spatial resolutions, and (ii) rainfall uncertainty, are propagated through the hydrogeological model of the system. Our results demonstrate that RSV has a significant impact on the modeled response of the system, by specifically affecting groundwater recharge and runoff generation, and thereby propagating through to various other related hydrological responses (river discharge, river-aquifer exchange, groundwater levels). These results call into question the validity of management decisions made using hydrological models calibrated or forced with spatially lumped rainfall.

  13. Temporal and spatial variability of the Denmark Strait Overflow

    NASA Astrophysics Data System (ADS)

    Moritz, Martin; Nunes, Nuno; Jochumsen, Kerstin; Quadfasel, Detlef

    2016-04-01

    The Denmark Strait Overflow (DSO) represents about half of the export of dense waters formed in the Nordic Seas to the deep circulation in the North Atlantic. The passage connecting the two is wider than the Rossby radius of deformation, and highly variable meso-scale current fluctuations are observed in the overflow. In the summer of 2014, the mooring array used for monitoring the Denmark Strait Overflow was expanded from two to five moorings in order to better resolve its spatial variability. Continuous measurements of the velocity field were made using four acoustic profilers (ADCP) and one point current meter (RCM). The instruments were deployed along the sill between the deepest point and 33 km westward of it, towards the Greenland shelf. A descriptive analysis of the structure of the velocity field at the Denmark Strait sill is presented, along with its spatial and temporal variability. The fluctuations are dominated by passing meso-scale vortices, pulsating changes in the strength of the overflow and shifts in the location of the Polar Front. These changes and their respective contribution to the variability of the flow field are discussed with relation to the different source water masses for the DSO. The relationship between spatial coherence and temporal variability on daily to monthly time scales is explored, and the influence of meso-scale eddies on daily to weekly transport estimates is quantified. The results of the analysis are used to develop a measurement strategy for unbiased DSO transport estimates.

  14. Farmer decision making and spatial variables in northern Thailand

    NASA Astrophysics Data System (ADS)

    Fox, Jefferson; Kanter, Rebekah; Yarnasarn, Sanay; Ekasingh, Methi; Jones, Royce

    1994-05-01

    This research has two interrelated objectives. The first is to determine the extent to which a relationship exists between farmer characteristics and farming practices in three villages in northern Thailand. The second is to use standard statistical methods for incorporating spatial variables into the analysis and to assess the effects of these variables on farmer decision making. The data base includes information on the location and size of villages, roads, streams, and fields; a digital elevation model with information on elevation, slope, and aspect; and information keyed to individual fields on crops and cropping methods and the ethnicity, income, and religion of farmers. The map data (517 plots) were entered into a computerized geographic information systems (GIS). Results suggest several hypotheses about the relationships between land use and owner characteristics. More significantly, the study concludes that spatial analysis appears to be most useful when the dependent variable is either continuous or ordinal. The outlook is not quite as optimistic when the dependent variable is a nonordinal categorical variable. Before spatial analysis can be applied regularly to social science data, better computational tools need to be developed.

  15. Impact of rainfall spatial variability on Flash Flood Forecasting

    NASA Astrophysics Data System (ADS)

    Douinot, Audrey; Roux, Hélène; Garambois, Pierre-André; Larnier, Kevin

    2014-05-01

    According to the United States National Hazard Statistics database, flooding and flash flooding have caused the largest number of deaths of any weather-related phenomenon over the last 30 years (Flash Flood Guidance Improvement Team, 2003). Like the storms that cause them, flash floods are very variable and non-linear phenomena in time and space, with the result that understanding and anticipating flash flood genesis is far from straightforward. In the U.S., the Flash Flood Guidance (FFG) estimates the average number of inches of rainfall for given durations required to produce flash flooding in the indicated county. In Europe, flash flood often occurred on small catchments (approximately 100 km2) and it has been shown that the spatial variability of rainfall has a great impact on the catchment response (Le Lay and Saulnier, 2007). Therefore, in this study, based on the Flash flood Guidance method, rainfall spatial variability information is introduced in the threshold estimation. As for FFG, the threshold is the number of millimeters of rainfall required to produce a discharge higher than the discharge corresponding to the first level (yellow) warning of the French flood warning service (SCHAPI: Service Central d'Hydrométéorologie et d'Appui à la Prévision des Inondations). The indexes δ1 and δ2 of Zoccatelli et al. (2010), based on the spatial moments of catchment rainfall, are used to characterize the rainfall spatial distribution. Rainfall spatial variability impacts on warning threshold and on hydrological processes are then studied. The spatially distributed hydrological model MARINE (Roux et al., 2011), dedicated to flash flood prediction is forced with synthetic rainfall patterns of different spatial distributions. This allows the determination of a warning threshold diagram: knowing the spatial distribution of the rainfall forecast and therefore the 2 indexes δ1 and δ2, the threshold value is read on the diagram. A warning threshold diagram is

  16. Spatial variability of the dehydrogenase activity in forest soils

    NASA Astrophysics Data System (ADS)

    Błońska, Ewa; Lasota, Jarosław

    2014-05-01

    The aim of this study was to assess the spatial variability of the dehydrogenase activity (DH) in forest soils using geostatistics. We have studied variability soil dehydrogenase and their relationship with variability of some physic-chemical properties. Two study areas (A and B) were set up in southern Poland in the Zlotoryja Forest District. Study areas were covered by different types of vegetation (A- broadleaf forest with beech, ash and sycamore), B- coniferous forest with Norway spruce). The soils were classified as Dystric Cambisols (WRB 2006). The samples for laboratory testing were collected from 49 places on each areas. 15 cm of surface horizon of soil were taken (with previously removed litter). Dehydrogenase activity was marked with Lenhard's method according to the Casida procedure. Soil pH, nitrogen (N) and soil organic carbon (C) content (by LECO CNS 2000 carbon analyzer) was marked. C/N ratio was calculated. Particle size composition was determined using laser diffraction. Statistical analysis were performed using STATISTICA 10 software. Geostatistical analysis and mapping were done by application of GS 9+ (Gamma Design) and Surfer 11 (Golden Software). The activity of DH ranged between 5,02 and 71,20 mg TPP• kg-1 •24 h-1 on the A area and between 0,94 and 16,47 mg TPP• kg-1 •24 h-1. Differences in spatial variability of the analised features were noted. The variability of dehydrogenase activity on the A study area was described by an exponential model, whereas on the B study area the spatial correlation has not been noted. The relationship of dehydrogenase activity with the remaining parameters of soil was noted only in the case of A study area. The variability of organic carbon content on the A and B study areas were described by an exponential model. The variability of nitrogen content on both areas were described by an spherical model.

  17. Analytical model of reactive transport processes with spatially variable coefficients.

    PubMed

    Simpson, Matthew J; Morrow, Liam C

    2015-05-01

    Analytical solutions of partial differential equation (PDE) models describing reactive transport phenomena in saturated porous media are often used as screening tools to provide insight into contaminant fate and transport processes. While many practical modelling scenarios involve spatially variable coefficients, such as spatially variable flow velocity, v(x), or spatially variable decay rate, k(x), most analytical models deal with constant coefficients. Here we present a framework for constructing exact solutions of PDE models of reactive transport. Our approach is relevant for advection-dominant problems, and is based on a regular perturbation technique. We present a description of the solution technique for a range of one-dimensional scenarios involving constant and variable coefficients, and we show that the solutions compare well with numerical approximations. Our general approach applies to a range of initial conditions and various forms of v(x) and k(x). Instead of simply documenting specific solutions for particular cases, we present a symbolic worksheet, as supplementary material, which enables the solution to be evaluated for different choices of the initial condition, v(x) and k(x). We also discuss how the technique generalizes to apply to models of coupled multispecies reactive transport as well as higher dimensional problems. PMID:26064648

  18. Analytical model of reactive transport processes with spatially variable coefficients

    PubMed Central

    Simpson, Matthew J.; Morrow, Liam C.

    2015-01-01

    Analytical solutions of partial differential equation (PDE) models describing reactive transport phenomena in saturated porous media are often used as screening tools to provide insight into contaminant fate and transport processes. While many practical modelling scenarios involve spatially variable coefficients, such as spatially variable flow velocity, v(x), or spatially variable decay rate, k(x), most analytical models deal with constant coefficients. Here we present a framework for constructing exact solutions of PDE models of reactive transport. Our approach is relevant for advection-dominant problems, and is based on a regular perturbation technique. We present a description of the solution technique for a range of one-dimensional scenarios involving constant and variable coefficients, and we show that the solutions compare well with numerical approximations. Our general approach applies to a range of initial conditions and various forms of v(x) and k(x). Instead of simply documenting specific solutions for particular cases, we present a symbolic worksheet, as supplementary material, which enables the solution to be evaluated for different choices of the initial condition, v(x) and k(x). We also discuss how the technique generalizes to apply to models of coupled multispecies reactive transport as well as higher dimensional problems. PMID:26064648

  19. Sparse modeling of spatial environmental variables associated with asthma.

    PubMed

    Chang, Timothy S; Gangnon, Ronald E; David Page, C; Buckingham, William R; Tandias, Aman; Cowan, Kelly J; Tomasallo, Carrie D; Arndt, Brian G; Hanrahan, Lawrence P; Guilbert, Theresa W

    2015-02-01

    Geographically distributed environmental factors influence the burden of diseases such as asthma. Our objective was to identify sparse environmental variables associated with asthma diagnosis gathered from a large electronic health record (EHR) dataset while controlling for spatial variation. An EHR dataset from the University of Wisconsin's Family Medicine, Internal Medicine and Pediatrics Departments was obtained for 199,220 patients aged 5-50years over a three-year period. Each patient's home address was geocoded to one of 3456 geographic census block groups. Over one thousand block group variables were obtained from a commercial database. We developed a Sparse Spatial Environmental Analysis (SASEA). Using this method, the environmental variables were first dimensionally reduced with sparse principal component analysis. Logistic thin plate regression spline modeling was then used to identify block group variables associated with asthma from sparse principal components. The addresses of patients from the EHR dataset were distributed throughout the majority of Wisconsin's geography. Logistic thin plate regression spline modeling captured spatial variation of asthma. Four sparse principal components identified via model selection consisted of food at home, dog ownership, household size, and disposable income variables. In rural areas, dog ownership and renter occupied housing units from significant sparse principal components were associated with asthma. Our main contribution is the incorporation of sparsity in spatial modeling. SASEA sequentially added sparse principal components to Logistic thin plate regression spline modeling. This method allowed association of geographically distributed environmental factors with asthma using EHR and environmental datasets. SASEA can be applied to other diseases with environmental risk factors. PMID:25533437

  20. Sparse modeling of spatial environmental variables associated with asthma

    PubMed Central

    Chang, Timothy S.; Gangnon, Ronald E.; Page, C. David; Buckingham, William R.; Tandias, Aman; Cowan, Kelly J.; Tomasallo, Carrie D.; Arndt, Brian G.; Hanrahan, Lawrence P.; Guilbert, Theresa W.

    2014-01-01

    Geographically distributed environmental factors influence the burden of diseases such as asthma. Our objective was to identify sparse environmental variables associated with asthma diagnosis gathered from a large electronic health record (EHR) dataset while controlling for spatial variation. An EHR dataset from the University of Wisconsin’s Family Medicine, Internal Medicine and Pediatrics Departments was obtained for 199,220 patients aged 5–50 years over a three-year period. Each patient’s home address was geocoded to one of 3,456 geographic census block groups. Over one thousand block group variables were obtained from a commercial database. We developed a Sparse Spatial Environmental Analysis (SASEA). Using this method, the environmental variables were first dimensionally reduced with sparse principal component analysis. Logistic thin plate regression spline modeling was then used to identify block group variables associated with asthma from sparse principal components. The addresses of patients from the EHR dataset were distributed throughout the majority of Wisconsin’s geography. Logistic thin plate regression spline modeling captured spatial variation of asthma. Four sparse principal components identified via model selection consisted of food at home, dog ownership, household size, and disposable income variables. In rural areas, dog ownership and renter occupied housing units from significant sparse principal components were associated with asthma. Our main contribution is the incorporation of sparsity in spatial modeling. SASEA sequentially added sparse principal components to Logistic thin plate regression spline modeling. This method allowed association of geographically distributed environmental factors with asthma using EHR and environmental datasets. SASEA can be applied to other diseases with environmental risk factors. PMID:25533437

  1. Ranking spatially and temporally variable Greenland ice surface melt factors

    NASA Astrophysics Data System (ADS)

    Box, Jason; Mottram, Ruth; Langen, Peter; Boberg, Fredrik; Promice Team

    2014-05-01

    Greenland ice sheet surface melt water production is evaluated via a spatially distributed surface energy budget analysis of the 14 summers spanning 2000-2013. Key ingredients are DMI HIRHAM5 5km x 5km output and NASA MOD10A1 daily albedo. The HIRHAM5 simulated downward solar and infrared fluxes and turbulent fluxes are compared with in-situ data from the Danish PROMICE.org automatic weather stations. The seasonally and spatially evolving relative importance of individual surface energy budget components yields detailed insight into physical processes driving melt variability with some surprising implications to ice sheet surface mass balance sensitivity to climate change.

  2. DOE small scale fuel alcohol plant design

    SciTech Connect

    LaRue, D.M.; Richardson, J.G.

    1980-01-01

    The Department of Energy, in an effort to facilitate the deployment of rural-based ethanol production capability, has undertaken this effort to develop a basic small-scale plant design capable of producing anhydrous ethanol. The design, when completed, will contain all necessary specifications and diagrams sufficient for the construction of a plant. The design concept is modular; that is, sections of the plant can stand alone or be integrated into other designs with comparable throughput rates. The plant design will be easily scaled up or down from the designed flow rate of 25 gallons of ethanol per hour. Conversion factors will be provided with the final design package to explain scale-up and scale-down procedures. The intent of this program is to provide potential small-scale producers with sound information about the size, engineering requirements, costs and level of effort in building such a system.

  3. Spatial uncertainty in remote sensing generated hydrological variables

    NASA Astrophysics Data System (ADS)

    Mendiguren González, Gorka; Stisen, Simon

    2016-04-01

    The use of satellite remote sensing (RS) has proven its potential to generate different hydrological variables such as Land Surface Temperature (LST), Leaf Area Index (LAI) or Evapotranspiration (ET) among others. In the case of ET different methods combine spectral and thermal information to estimate Actual ET (aET) coincident with satellite overpass. These estimates from space has become popular in the hydrological modeling community. The information obtained from RS estimates can be used to calibrate and validate hydrological models not just at single points or catchment averages, but also the simulated spatial patterns. It is a common assumption that although the RS estimates are uncertain, their strength lies in the spatial pattern information, due to the unprecedented spatial coverage of the observations. When spatial patterns obtained from remote sensing estimates are intended for evaluating the spatial patterns of distributed hydrological models, it will however be necessary to challenge that assumption. This study aims at quantifying the uncertainty of the estimated spatial pattern of temporally aggregated monthly LST and AET maps derived from the MODIS satellite. The proposed approach is based on a cluster analysis performed on hundreds of possible realizations of the estimates generated by sampling within the uncertainty of the individual pixels estimates and taking into account temporal variation and the correlation length of the error. The result is not only monthly maps of LST and AET, but also maps of the uncertainty of the spatial pattern. This type of information is critical when evaluating the spatial pattern performance of hydrological models, because the performance criteria can be adjusted for areas of high and low confidence in the observational data set. The resulting maps are finally utilized for an evaluation of the spatial performance of the 43,000 km2 national hydrological model of Denmark.

  4. Use of the Soil Management Assessment Framework in Spatially Variable Fields

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil management is typically applied to tracts of land exhibiting spatial variability. Intensive soil sampling to quantify this variability is labor intensive and expensive. Additional approaches are needed to assess soil management within spatially variable fields. Apparent electrical conductivity ...

  5. Small-scale features of temperature and salinity surface fields in the Coral Sea

    NASA Astrophysics Data System (ADS)

    Maes, Christophe; Dewitte, Boris; Sudre, Joël.; Garçon, Véronique; Varillon, David

    2013-10-01

    The small-scale features in sea surface temperature and salinity fields (SST and SSS) of the Coral Sea are examined using high horizontal spatial and short-term temporal in situ measurements. These features are extracted from thermosalinographs (TSGs) gathered onboard commercial and research vessels and at one long-term fixed station. The analyses are performed along the vessel tracks and the structures of small-scale features are extracted by high-pass spatial filtering the original TSG data. For SSS, it is shown that the features at the scale of mesoscale eddies (˜100 km) vary from about -1.1 to +0.6 psu in the Coral Sea region. Processes sustaining such range include rainfall events, stirring by mesoscale eddies, and the latitudinal displacement of the sharp front associated with the edge of the Western Pacific Warm Pool at the seasonal time scales. The TSG data have revealed the presence of a sharp front (0.4-0.6 psu) between the subtropical and equatorial waters instead of a smooth gradient in the standard SSS climatologies. Within the context of recent remotely sensed observations of salinity, this could represent an important limitation for the validation and calibration of satellite products. In addition to these spatial considerations, temporal variations at one long-term station near Vanuatu show that the coupled air-sea responses to intraseasonal tropical variability, such as the Madden-Julian Oscillation, may have a signature in both SST and SSS fields. However, this response is found to be complex and not necessarily in phase. In the Coral Sea region, our results suggest that MJO-induced variability on SST and SSS exhibit little coherency at the seasonal time scales.

  6. Small Scale Structure and Turbulence in the Interstellar Medium

    NASA Astrophysics Data System (ADS)

    Spangler, Steven

    Radio scintillation observations show fluctuations in electromagnetic wave properties (intensity, interferometer phase, etc) on spatial scales as small as hundreds of kilometers. These observations indicate that irregularities in the interstellar plasma density also exist on these scales. In this talk I will discuss what observations of these irregularities tell us about the nature of interstellar turbulence. I will be particularly interested in information on suitable mathematical models of such turbulence, as well as the mechanisms responsible for its generation. The small scale irregularities are important because their physics is arguably relatively simple; they probably respond to temporal and spatial variations in the turbulent kinetic and magnetic energy densities. Physical processes such as gravitation, radiative cooling, and ion-neutral collisional effects are important on larger scales and probably complicate the interpretation of observations on such scales. However, they should be unimportant on the scales probed by radio scintillations. The generally-observed Kolmogorov spectrum for these irregularities strongly indicates the existence of an inertial subrange of density and (probably) magnetic field and fluid velocity from scales of order 1015 cm to as small as 10^7 cm. This observation indicates that ion-neutral collisional or ambipolar effects, which would set an inner scale near the upper end of this range, cannot be dominant in the interstellar plasma probed by radio wave scintillations. One can speculate that structures formed by ion-neutral effects might manifest themselves in strong refractive scintillation phenomena, enhanced low frequency variability, and perhaps the "tiny-scale" ISM features (Heiles 1997, ApJ 481, 193). Interstellar scintillation observations also present consistent evidence for anisotropy of scattering, indicating anisotropic, magnetic field-aligned density irregularities. From existent observations, we would conclude that

  7. Hydrological response to changing climate conditions: Spatial streamflow variability in the boreal region

    NASA Astrophysics Data System (ADS)

    Teutschbein, Claudia; Grabs, Thomas; Karlsen, Reinert H.; Laudon, Hjalmar; Bishop, Kevin

    2016-04-01

    It has long been recognized that streamflow-generating processes are not only dependent on climatic conditions, but also affected by physical catchment properties such as topography, geology, soils and land cover. We hypothesize that these landscape characteristics do not only lead to highly variable hydrologic behavior of rather similar catchments under the same stationary climate conditions (Karlsen et al., 2014), but that they also play a fundamental role for the sensitivity of a catchment to a changing climate (Teutschbein et al., 2015). A multi-model ensemble based on 15 regional climate models was combined with a multi-catchment approach to explore the hydrologic sensitivity of 14 partially nested and rather similar catchments in Northern Sweden to changing climate conditions and the importance of small-scale spatial variability. Current (1981-2010) and future (2061-2090) streamflow was simulated with the HBV model. As expected, projected increases in temperature and precipitation resulted in increased total available streamflow, with lower spring and summer flows, but substantially higher winter streamflow. Furthermore, significant changes in flow durations with lower chances of both high and low flows can be expected in boreal Sweden in the future. This overall trend in projected streamflow pattern changes was comparable among the analyzed catchments while the magnitude of change differed considerably. This suggests that catchments belonging to the same region can show distinctly different degrees of hydrological responses to the same external climate change signal. We reason that differences in spatially distributed physical catchment properties at smaller scales are not only of great importance for current streamflow behavior, but also play a major role as first-order control for the sensitivity of catchments to changing climate conditions. References Karlsen, R.H., T. Grabs, K. Bishop, H. Laudon, and J. Seibert (2014). Landscape controls on

  8. Effects of spatial variability and scale on areal -average evapotranspiration

    NASA Technical Reports Server (NTRS)

    Famiglietti, J. S.; Wood, Eric F.

    1993-01-01

    This paper explores the effect of spatial variability and scale on areally-averaged evapotranspiration. A spatially-distributed water and energy balance model is employed to determine the effect of explicit patterns of model parameters and atmospheric forcing on modeled areally-averaged evapotranspiration over a range of increasing spatial scales. The analysis is performed from the local scale to the catchment scale. The study area is King's Creek catchment, an 11.7 sq km watershed located on the native tallgrass prairie of Kansas. The dominant controls on the scaling behavior of catchment-average evapotranspiration are investigated by simulation, as is the existence of a threshold scale for evapotranspiration modeling, with implications for explicit versus statistical representation of important process controls. It appears that some of our findings are fairly general, and will therefore provide a framework for understanding the scaling behavior of areally-averaged evapotranspiration at the catchment and larger scales.

  9. Spatial and temporal variability of lightings over Greece

    NASA Astrophysics Data System (ADS)

    Nastos, P. T.; Matsangouras, J. T.

    2010-09-01

    Lightings are the most powerful and spectacular natural phenomena in the lower atmosphere, being a major cause of storm related deaths. Cloud-to-ground lightning can kill and injure people by direct or indirect means. Lightning affects the many electrochemical systems in the body causing nerve damage, memory loss, personality change, and emotional problems. Besides, among the various nitrogen oxides sources, the contribution from lightning likely represents the largest uncertainty. In this study, the spatial and temporal variability of recorded lightings over Greece during the period from January 1, 2008 to December 31, 2009, were analyzed. The data for retrieving the location and time-of-occurrence of lightning were acquired from Hellenic National Meteorological Service (HNMS) archive dataset. An operational lighting detector network was established in 2007 by HNMS consisted of eight time-of-arrival sensors (TOA), spatially distributed across Greek territory. The spatial variability of lightings revealed their incidence within specific geographical sub-regions while the temporal variability concerning the seasonal, monthly and daily distributions resulted in better understanding of the time of lightings’ occurrence. All the analyses were carried out with respect to cloud to cloud, cloud to ground and ground to cloud lightings, within the examined time period.

  10. Geomorphic and substrate controls on spatial variability in river solute transport and biogeochemical cycling

    NASA Astrophysics Data System (ADS)

    Blaen, Phillip; Kurz, Marie; Knapp, Julia; Mendoza-Lera, Clara; Lee-Cullin, Joe; Klaar, Megan; Drummond, Jen; Jaeger, Anna; Zarnetske, Jay; Lewandowski, Joerg; Marti, Eugenia; Ward, Adam; Fleckenstein, Jan; Datry, Thibault; Larned, Scott; Krause, Stefan

    2016-04-01

    Nutrient concentrations in surface waters and groundwaters are increasing in many agricultural catchments worldwide as a result of anthropogenic activities. Increasing geomorphological heterogeneity in river channels may help to attenuate nutrient pollution by facilitating water exchange fluxes with the hyporheic zone; a site of intense microbial activity where biogeochemical transformation rates (e.g. denitrification) can be high. However, the controls on spatial variability in biogeochemical cycling, particularly at scales relevant for river managers, are not well understood. Here, we aimed to assess: 1) how differences in geomorphological heterogeneity control river solute transport and rates of biogeochemical cycling at sub-reach scales (102 m); and 2) the relative magnitude of these differences versus those relating to reach scale substrate variability (103 m). We used the reactive 'smart' tracer resazurin (Raz), a weakly fluorescent dye that transforms to highly fluorescent resorufin (Rru) under mildly reducing conditions, as a proxy to assess rates of biogeochemical cycling in a lowland river in southern England. Solute tracer tests were conducted in two reaches with contrasting substrates: one sand-dominated and the other gravel-dominated. Each reach was divided into sub-reaches that varied in geomorphic complexity (e.g. by the presence of pool-riffle sequences or the abundance of large woody debris). Slug injections of Raz and the conservative tracer fluorescein were conducted in each reach during baseflow conditions (Q ≈ 80 L/s) and breakthrough curves monitored using in-situ fluorometers. Preliminary results indicate overall Raz:Rru transformation rates in the gravel-dominated reach were more than 50% higher than those in the sand-dominated reach. However, high sub-reach variability in Raz:Rru transformation rates and conservative solute transport parameters suggests small-scale targeted management interventions to alter geomorphic heterogeneity may be

  11. [Scale-dependency of spatial variability of soil available nutrients].

    PubMed

    Yang, Qi-Yong; Yang, Jing-Song; Liu, Guang-Ming

    2011-02-01

    With the support of GIS and by using classical statistics and geostatistics methods, the spatial variability of soil available P (AP) and available K (AK) in cultivated lands in Yucheng City of Shandong Province was approached at county and township scales. The results showed that both the soil AP and AK followed the logarithmic normal distribution, with the coefficient of variation (CV) at the two scales being 26.5% - 36.6% and presenting a moderate variation. With the decrease of the scale, the CV of the soil AP and AK increased. Both the soil AP and AK were spatially correlated with scale. At county scale, the soil AP and AK had a larger spatial correlation distance, being 9.0 km and 26.5 km, respectively; while at township scale, the soil AP and AK had a smaller spatial correlation distance, being 1.7 km and 2.8 km, respectively. The spatial distribution of the soil AP and AK at the two scales was obviously different, which was mainly affected by structural factors and random factors. PMID:21608258

  12. Bayesian Variable Selection for Multivariate Spatially-Varying Coefficient Regression

    PubMed Central

    Reich, Brian J.; Fuentes, Montserrat; Herring, Amy H.; Evenson, Kelly R.

    2009-01-01

    Summary Physical activity has many well-documented health benefits for cardiovascular fitness and weight control. For pregnant women, the American College of Obstetricians and Gynecologists currently recommends 30 minutes of moderate exercise on most, if not all, days; however, very few pregnant women achieve this level of activity. Traditionally, studies have focused on examining individual or interpersonal factors to identify predictors of physical activity. There is a renewed interest in whether characteristics of the physical environment in which we live and work may also influence physical activity levels. We consider one of the first studies of pregnant women that examines the impact of characteristics of the built environment on physical activity levels. Using a socioecologic framework, we study the associations between physical activity and several factors including personal characteristics, meteorological/air quality variables, and neighborhood characteristics for pregnant women in four counties of North Carolina. We simultaneously analyze six types of physical activity and investigate cross-dependencies between these activity types. Exploratory analysis suggests that the associations are different in different regions. Therefore we use a multivariate regression model with spatially-varying regression coefficients. This model includes a regression parameter for each covariate at each spatial location. For our data with many predictors, some form of dimension reduction is clearly needed. We introduce a Bayesian variable selection procedure to identify subsets of important variables. Our stochastic search algorithm determines the probabilities that each covariate’s effect is null, non-null but constant across space, and spatially-varying. We found that individual level covariates had a greater influence on women’s activity levels than neighborhood environmental characteristics, and some individual level covariates had spatially-varying associations with

  13. Wet tropospheric delay spatial variability over terrestrial water bodies

    NASA Astrophysics Data System (ADS)

    Clark, E.; Moller, D.; Andreadis, K.; Lettenmaier, D. P.

    2013-12-01

    Among the sources of uncertainty in radar altimetry measurements of inland water bodies is the signal delay associated with space-time variations in water vapor in the atmosphere. Over the ocean, zenith wet tropospheric path delays (PD) can be measured by satellite microwave radiometry; however, the high brightness temperature of land prevents the use of these techniques over inland waters. SAR-based Atmospheric Phase Screens can be estimated over land, but not over water bodies. Radiosonde- and GPS-based estimates of PD over land are available, yet these measurements occur at specific, sparse locations. Atmospheric models are therefore the best source of information about space-time variations in PD, where observations (e.g., from radiosonde and GPS) are incorporated via data assimilation. The upcoming Surface Water and Ocean Topography mission (SWOT) will use Interferometric Synthetic Aperture Radar (InSAR) in Ka-band, at a high incidence angle, to measure temporal variations in water elevation, slope, and extent in rivers, lakes, and reservoirs. Images will be collected over a 120-km wide swath with <100 m spatial resolution and ~1 cm height precision when averaged over a 1 km2 area, with a 21-day repeat cycle. At present, the spatial and temporal variability of PD at spatial scales relevant to the mission's inland water objectives (e.g., measurement of variations in the storage of reservoirs and lakes with spatial extent order 1 sq. km and larger) is an open question. We report the results of simulations of PD based on simulations from the Weather Research and Forecasting (WRF) numerical weather prediction model. We consider two domains within the continental U.S.: 1) the Pacific Northwest (at 4-km and 4/3-km spatial resolutions, via WRF results provided by the Northwest Modeling Consortium), and 2) sections of New Mexico, Oklahoma, and Texas (at 2.33-km spatial resolution, via simulations performed for this study). We then investigate the spatial and temporal

  14. Small-Scale High-Performance Optics

    SciTech Connect

    WILSON, CHRISTOPHER W.; LEGER, CHRIS L.; SPLETZER, BARRY L.

    2002-06-01

    Historically, high resolution, high slew rate optics have been heavy, bulky, and expensive. Recent advances in MEMS (Micro Electro Mechanical Systems) technology and micro-machining may change this. Specifically, the advent of steerable sub-millimeter sized mirror arrays could provide the breakthrough technology for producing very small-scale high-performance optical systems. For example, an array of steerable MEMS mirrors could be the building blocks for a Fresnel mirror of controllable focal length and direction of view. When coupled with a convex parabolic mirror the steerable array could realize a micro-scale pan, tilt and zoom system that provides full CCD sensor resolution over the desired field of view with no moving parts (other than MEMS elements). This LDRD provided the first steps towards the goal of a new class of small-scale high-performance optics based on MEMS technology. A large-scale, proof of concept system was built to demonstrate the effectiveness of an optical configuration applicable to producing a small-scale (< 1cm) pan and tilt imaging system. This configuration consists of a color CCD imager with a narrow field of view lens, a steerable flat mirror, and a convex parabolic mirror. The steerable flat mirror directs the camera's narrow field of view to small areas of the convex mirror providing much higher pixel density in the region of interest than is possible with a full 360 deg. imaging system. Improved image correction (dewarping) software based on texture mapping images to geometric solids was developed. This approach takes advantage of modern graphics hardware and provides a great deal of flexibility for correcting images from various mirror shapes. An analytical evaluation of blur spot size and axi-symmetric reflector optimization were performed to address depth of focus issues that occurred in the proof of concept system. The resulting equations will provide the tools for developing future system designs.

  15. Shortwave surface radiation budget network for observing small-scale cloud inhomogeneity fields

    NASA Astrophysics Data System (ADS)

    Madhavan, B. L.; Kalisch, J.; Macke, A.

    2015-03-01

    As part of the High Definition Clouds and Precipitation for advancing Climate Prediction Observational Prototype Experiment (HOPE), a high spatial density network of 99 silicon photodiode pyranometers was set up around Jülich (10 km x 12 km area) from April to July 2013, to capture the variability in the radiation field at the surface induced by small-scale cloud inhomogeneity. Each of these autonomously operated pyranometer stations was equipped with weather sensors for simultaneous measurements of ambient air temperature and relative humidity. In this paper, we provide the details of this unique setup of the pyranometer network and the data analysis with initial quality screening procedure we adopted. We also present some exemplary cases consisting of the days with clear, broken cloudy and overcast skies to assess our spatio-temporal observations from the network, and validate their consistency with other collocated radiation measurements available during the HOPE period.

  16. Philippines: Small-scale renewable energy update

    SciTech Connect

    1997-12-01

    This paper gives an overview of the application of small scale renewable energy sources in the Philippines. Sources looked at include solar, biomass, micro-hydroelectric, mini-hydroelectric, wind, mini-geothermal, and hybrid. A small power utilities group is being spun off the major utility, to provide a structure for developing rural electrification programs. In some instances, private companies have stepped forward, avoiding what is perceived as overwhelming beaurocracy, and installed systems with private financing. The paper provides information on survey work which has been done on resources, and the status of cooperative programs to develop renewable systems in the nation.

  17. Small-scale dynamic gap test

    NASA Astrophysics Data System (ADS)

    Cook, Malcolm David

    2012-03-01

    In this paper we describe a new small-scale test, requiring small quantities of energetic material, designed using our CHARM ignition and growth routine in the DYNA2D hydrocode. The new test is a modified gap test and uses detonating nitromethane to provide dynamic confinement (instead of a thick metal case) whilst exposing the sample to a long duration shock wave. This arrangement allows less reactive materials that are below their critical diameter, more time to react. We present details of the modelling of the test together with some preliminary experiments to demonstrate the potential of the new test method.

  18. Small-Scale Hydroelectric Power Demonstration Project

    SciTech Connect

    Gleeson, L.

    1991-12-01

    The US Department of Energy Field Office, Idaho, Small-Scale Hydroelectric Power Program was initiated in conjunction with the restoration of three power generating plants in Idaho Falls, Idaho, following damage caused by the Teton Dam failure on June 5, 1976. There were many parties interested in this project, including the state and environmental groups, with different concerns. This report was prepared by the developer and describes the design alternatives the applicant provided in an attempt to secure the Federal Energy Regulatory Commission license. Also included are correspondence between the related parties concerning the project, major design alternatives/project plan diagrams, the license, and energy and project economics.

  19. Small-scale physics of the ocean

    NASA Technical Reports Server (NTRS)

    Caldwell, Douglas R.

    1987-01-01

    Observations and theoretical models of small-scale phenomena in the oceans are reviewed, with a focus on progress during the period 1983-1986. Topics examined include surface layers, equatorial turbulence, off-equator mixed layers, the scaling of mixing, turbulence concepts, laboratory results, internal waves and mixing, rings, the nature of the bottom layer, double diffusion and intrusions, salt fingers, and biological interactions. Also discussed are developments in instrumentation (fast sampling profilers with upward-profiling capability, deep profilers, ship-motion correction, horizontal samplers, small submersibles, submarines, towed packages, conductivity sensors, dissolved-oxygen sensors, and acoustic Doppler current profilers) and goals for future research.

  20. Chapman Conference on Spatial Variability in Hydrologic Modeling

    NASA Astrophysics Data System (ADS)

    Woolhiser, D. A.; Morel-Seytoux, H. J.

    The AGU Chapman Conference on Spatial Variability in Hydrologic Modeling was held July 21-23, 1981, at the Colorado State University Pingree Park Campus, located in the mountains some 88.5 km (55 miles) west of Fort Collins, Colorado. The conference was attended by experimentalists and theoreticians from a wide range of disciplines, including geology, hydrology, civil engineering, watershed science, chemical engineering, geography, statistics, mathematics, meteorology, and soil science. The attendees included researchers at various levels of research experience, including a large contingent of graduate students and many senior scientists.The conference goal was to review progress and discuss research approaches to the spatial variability of catchment surface and subsurface properties in a distributed modeling context. Mathematical models of water movement dynamics within a catchment consist of linked partial differential equations that describe free surface flow and unsaturated and saturated flow in porous media. Such models are utilized extensively in attempts to understand and predict the environmental consequences of human activities such as agricultural land management, waste disposal, urbanization, etc. We are concerned with the spatial structure of the parameters in such models, the precipitation input, and the geometric complexity of the system boundaries. The emphasis of this conference was on surface and subsurface hydrological process and their interactions.

  1. Temporal Changes in the Spatial Variability of Soil Nutrients

    SciTech Connect

    Hoskinson, Reed Louis; Hess, John Richard; Alessi, Randolph Samuel

    1999-07-01

    This paper reports the temporal changes in the spatial variability of soil nutrient concentrations across a field during the growing season, over a four-year period. This study is part of the Site-Specific Technologies for Agriculture (SST4Ag) precision farming research project at the INEEL. Uniform fertilization did not produce a uniform increase in fertility. During the growing season, several of the nutrients and micronutrients showed increases in concentration although no additional fertilization had occurred. Potato plant uptake did not explain all of these changes. Some soil micronutrient concentrations increased above levels considered detrimental to potatoes, but the plants did not show the effects in reduced yield. All the nutrients measured changed between the last sampling in the fall and the first sampling the next spring prior to fertilization. The soil microbial community may play a major role in the temporal changes in the spatial variability of soil nutrient concentrations. These temporal changes suggest potential impact when determining fertilizer recommendations, and when evaluating the results of spatially varying fertilizer application.

  2. Concentration and composition of polycyclic aromatic hydrocarbons (PAHs) in plastic pellets: implications for small-scale diagnostic and environmental monitoring.

    PubMed

    Fisner, Mara; Taniguchi, Satie; Majer, Alessandra P; Bícego, Márcia C; Turra, Alexander

    2013-11-15

    Plastic pellets may serve as a carrier of toxic contaminants, including polycyclic aromatic hydrocarbons (PAHs). Considering that beach morphodynamics and pellet distribution varied along the shore, and that contaminant sources may vary on different scales, it is expected that this variability is reflected in the concentration and composition of contaminants. This hypothesis was tested through a sampling of plastic pellets at 30 sites along the shore in Santos Bay (Brazil). The total PAH concentrations and the priority PAHs showed high variability, with no clear pattern. Their composition differed among the sampling sites; some of the compounds represent a potential risk to organisms. The sources of contamination, as indicated by the isomer ratios, were also variable among sites. The high small-scale spatial variability found here has implications for estimating the plastic pellet contamination on beaches, since a sample from a single site is unlikely to be representative of an entire beach. PMID:24125130

  3. Recession analysis across scales: The impact of both random and nonrandom spatial variability on aggregated hydrologic response

    NASA Astrophysics Data System (ADS)

    Chen, Bo; Krajewski, Witold F.

    2015-04-01

    Recession analysis across scales can provide insight into the spatial aggregation of hydrologic processes. Accordingly, we analyzed individual late-time recession curves from 25 nested USGS stream gauges over a period of ∼150 days with negligible precipitation during the 2012-2013 North American drought. These gauges are located in the Iowa and Cedar River basins and drain areas ranging from ∼70 to 17,000 km2. Our data analyses show that these late-time recession processes can be represented by a linear reservoir model with a constant recession time scale of about 34 days, indicating linear and homogeneous recession behaviors at the large scales investigated. However, others have shown that the early-time recession process becomes more nonlinear as spatial scale and, thus, spatial variability increases. We developed a distributed drainage model as a diagnostic tool to understand these seemingly contradictory recession characteristics at multiple spatial scales and different stages. With a hierarchical description of the recession variability at the hillslope scale, our model can simultaneously produce the increasing nonlinear early-time and the linear and homogenous late-time recession behaviors at larger scales. The hierarchical representation classifies hillslopes according to the Strahler orders of the stream links into which they drain. We postulate that a larger difference in recession behaviors will occur between hillslopes from different orders than between those from the same order. Overall, this study shows how the spatial randomness and nonrandomness of small-scale process variability control the hydrologic responses at larger scales and suggests a combined (nonrandom-random) representation of watersheds for aggregating hydrologic processes.

  4. Small-scale modular wind turbine

    NASA Astrophysics Data System (ADS)

    Bressers, Scott; Vernier, Chris; Regan, Jess; Chappell, Stephen; Hotze, Mark; Luhman, Stephen; Avirovik, Dragan; Priya, Shashank

    2010-04-01

    This study reports the design, fabrication, and implementation of a horizontal-axis, small-scale modular wind turbine termed as "small-scale wind energy portable turbine (SWEPT)". Portability, efficient operation at low wind speeds, and cost-effectiveness were the primary goals of SWEPT. The fabrication and component design for SWEPT are provided along with the modifications that can provide improvement in performance. A comparative analysis is presented with the prototype reported in literature. The results show that current version of SWEPT leads to 150% increase in output power. It was found that SWEPT can generate 160 mW power at rated wind speed of 7 mph and 500mW power at wind speeds above 10 mph with a cut-in wind speed of 3.8 mph. Furthermore, the prototype was subjected to field testing in which the average output was measured to be 40 mW despite the average wind distribution being centered around 3 mph.

  5. Expanded Small-Scale Shock Reactivity Test

    NASA Astrophysics Data System (ADS)

    Granholm, Richard

    2005-07-01

    Explosives react from a strong shock, even in quantities too small for detonation. The potential for a new material to be an explosive can be evaluated from this shock reactivity. The recently developed small-scale shock reactivity test (SSRT)ootnotetextH. W. Sandusky, R. H. Granholm, D. G. Bohl, ``Small-Scale Shock Reactivity Test,'' NSWC Technical Report (in publication), Naval Surface Warfare Center, Indian Head, MD 20640 uses very high confinement to allow prompt reactions to occur in less than half-gram samples well below critical diameter, with the reactions quantified by a dent in a soft aluminum witness block. This test has been expanded to simultaneously measure both early and late-time reactions from a single sample subjected to the output from an RP-80 detonator. The sample apparatus is further confined within a small chamber instrumented with a pressure gage for internal air blast. This provides a measure of late-time reactions, such as from fuel/air combustion. Results are shown from several simultaneous early- and late-reaction measurements.

  6. Small-scale universality in fluid turbulence

    PubMed Central

    Schumacher, Jörg; Scheel, Janet D.; Krasnov, Dmitry; Donzis, Diego A.; Yakhot, Victor; Sreenivasan, Katepalli R.

    2014-01-01

    Turbulent flows in nature and technology possess a range of scales. The largest scales carry the memory of the physical system in which a flow is embedded. One challenge is to unravel the universal statistical properties that all turbulent flows share despite their different large-scale driving mechanisms or their particular flow geometries. In the present work, we study three turbulent flows of systematically increasing complexity. These are homogeneous and isotropic turbulence in a periodic box, turbulent shear flow between two parallel walls, and thermal convection in a closed cylindrical container. They are computed by highly resolved direct numerical simulations of the governing dynamical equations. We use these simulation data to establish two fundamental results: (i) at Reynolds numbers Re ∼ 102 the fluctuations of the velocity derivatives pass through a transition from nearly Gaussian (or slightly sub-Gaussian) to intermittent behavior that is characteristic of fully developed high Reynolds number turbulence, and (ii) beyond the transition point, the statistics of the rate of energy dissipation in all three flows obey the same Reynolds number power laws derived for homogeneous turbulence. These results allow us to claim universality of small scales even at low Reynolds numbers. Our results shed new light on the notion of when the turbulence is fully developed at the small scales without relying on the existence of an extended inertial range. PMID:25024175

  7. Small-scale soil moisture determination with GPR

    NASA Astrophysics Data System (ADS)

    Igel, Jan; Preetz, Holger

    2010-05-01

    The knowledge of topsoil moisture distribution is an important input for modelling water flow and evapotranspiration which are essential processes in hydrology, meteorology, and agriculture. All these processes involve non-linear effects and thus the small-scale variability of input parameters play an important role. Using smoothed interpolations instead can cause significant biases. Lateral soil moisture distribution can be sensed by different techniques at various scales whereby geophysical methods provide spatial information which closes the gap between point measurements by classical soil scientific methods and measurements on the field or regional scale by remote sensing. Ground-penetrating radar (GPR) can be used to explore soil moisture on the field scale as propagation of electromagnetic waves is correlated to soil water content. By determining the velocity of the ground wave, which is a guided wave travelling along the soil surface, we can sense soil water content. This method has been applied to determine topsoil moisture for several years. We present a new groundwave technique which determines the velocity in between two receiving antennas which enables a higher lateral resolution (approx. 10 cm) compared to classical groundwave technique (half meter and more). We present synthetic data from finite-differences (FD) calculations as well as data from a sandbox experiment carried out under controlled conditions to demonstrate the performance of this method. Further, we carried out field measurements on two sites on a sandy soil which is used as grassland. The measurements were carried out in late summer at dry soil conditions. Soil moisture on the first site shows an isotropic pattern with correlation lengths of approx. 35 cm. We think this natural pattern is governed by rout distribution within the soil and the water uptake of vegetation. On the second site, soil moisture distribution shows a regular stripe pattern. As the land has been used as

  8. Spatial Variability of Streambed Hydraulic Conductivity of a Lowland River

    NASA Astrophysics Data System (ADS)

    Schneidewind, Uwe; Thornton, Steven; Van De Vijver, Ellen; Joris, Ingeborg; Seuntjens, Piet

    2015-04-01

    Streambed hydraulic conductivity K is a key physical parameter, which describes flow processes in the hyporheic zone (HZ), i.e. the dynamic interface between aquifers and streams or rivers. Knowledge of the spatial variability of K is also important for the interpretation of contaminant transport processes in the HZ. Streambed K can vary over several magnitudes at small spatial scales. It depends mostly on streambed sediment characteristics (e.g. effective porosity, grain size, packing), streambed processes (e.g. sedimentation, colmation and erosion) and the development of stream channel geometry and streambed morphology (e.g. dunes, anti-dunes, pool-riffle sequences, etc.). Although heterogeneous in natural streambeds, streambed K is often considered to be a constant parameter due to a lack of information on its spatial distribution. Here we show the spatial variability of streambed K for a small section of the River Tern, a lowland river in the UK. Streambed K was determined for more than 120 vertically and horizontally distributed locations from grain size analyses using four empirical approaches (Hazen, Beyer, Kozeny and the USBR model). Additionally, streambed K was estimated from falling head tests in 36 piezometers installed into the streambed on a 4 m by 16 m grid, by applying the Springer-Gelhar Model. For both methods streambed K followed a log-normal distribution. Variogram analysis was used to deduce the spatial variability of the streambed K values within several streambed profiles parallel and perpendicular to the main flow direction in the stream. Hydraulic conductivity Kg estimated from grain size analyses varied between 1 m/d and 155 m/d with standard deviations of 79% to 99% depending on the empirical approach used. Kh estimated from falling head tests varied between 1 m/d and 22 m/d with a standard deviation of about 50%, depending on the degree of anisotropy assumed. After rescaling the data to obtain a common sample support, Pearson correlation

  9. Effect of spatial variability of soil properties on infiltration

    NASA Astrophysics Data System (ADS)

    Domenech, Marisa; Castro Franco, Mauricio; Aparicio, Virginia; Costa, José Luis

    2013-04-01

    Topography and soil properties are key determinants of spatial variability of water content. Prediction of soil hydraulic properties are essential for modeling water flow and solute transport. In the southeastern of Buenos Aires Province, the effect of the relief on soil spatial variability is result of the relationship between elevation and effective depth (ED). Digital elevation models (DEM) provide quantitive information about relief. The objective was to determine the effect of spatial variability of soil properties on infiltration. The field was 50 ha and the soil classes were vertic Hapludoll, typic and petrocalcic Argiudoll. ED was measured using Gidding_Soil_Sampler® in 30x30m grid size. Elevation data were measured ussing a DGPS Trimble_R3®. From this, a DEM was generated. Two elevation and ED areas were delineated named High and Low zones. Three soil samples were taken at each zone with three replications at depth 0-30 and 30-90 cm. Texture, bulk density (δb) and organic matter (OM) were determined. A disc infiltrometer was used to determine the water infiltration rate (i). Clay content (As) and OM were homogeneous in the profile of the High zone. However, As content at 30-90 cm decreased in the Low zone. At the High zone, δb ranged from 1.31 to 1.34 g cm-3 and was higher than at the Low zone (δb=1.16 - 1.27 g cm-3). Also the i had less variation at the High zone. Under pressure head of -1 cm , the i increased in the Low zone. At lower pressure heads, the i was greater in the High zone. Higher i at the Low zone could be due to major ED, textural heterogeneity and higher OM content. Textural homogeneity, shallow ED and high δb allowed a more stable i at the High zone. Using topography and ED is a promising way of characterizing soil hydraulic behavior and its spatial variability across a field.

  10. Small-scale distribution of Solea solea and Solea senegalensis juveniles in the Tagus estuary (Portugal)

    NASA Astrophysics Data System (ADS)

    Vinagre, C.; Maia, A.; Reis-Santos, P.; Costa, M. J.; Cabral, H. N.

    2009-02-01

    The distribution of Solea solea and Solea senegalensis in the Tagus estuary was studied following a small-scale approach. Preliminary sampling revealed that sole concentrated in two areas within their nursery grounds, the main subtidal channel and a large intertidal mudflat. Beam trawls were conducted intensively in the two areas in July 2006. Depth, salinity and water temperature were measured. Substrate samples were collected for sediment type determination and macrobenthos identification and quantification. Generalized linear models were applied in order to explain the occurrence and variability of soles' densities, using depth, salinity, water temperature and abundance of polychaetes, oligochaetes, amphipods, isopods and bivalves as explanatory variables. While S. solea was more abundant in the main subtidal channel, a deeper, warmer and lower salinity area, S. senegalensis abundance was highest at the intertidal mudflat area. Presence of both species in the two areas was associated with abundance of polychaetes (generally with another variable associated), and for S. senegalensis in the subtidal channel it was associated with amphipods and depth. Abundance of S. solea in the main subtidal channel was associated mainly with polychaetes abundance, while that of S. senegalensis was associated with amphipods density. In the intertidal mudflat, bivalves and polychaetes presented significant relationships with both species densities. Some of the factors that had been reported to be important for the distribution of these species in previous studies also do so at a finer scale; however, this small-scale approach provided an in-depth knowledge on habitat selection and spatial segregation of these species within this nursery area.

  11. Small-scale variation of snow in a regional permafrost model

    NASA Astrophysics Data System (ADS)

    Gisnås, Kjersti; Westermann, Sebastian; Vikhamar Schuler, Thomas; Melvold, Kjetil; Etzelmüller, Bernd

    2016-06-01

    The strong winds prevalent in high altitude and arctic environments heavily redistribute the snow cover, causing a small-scale pattern of highly variable snow depths. This has profound implications for the ground thermal regime, resulting in highly variable near-surface ground temperatures on the metre scale. Due to asymmetric snow distributions combined with the nonlinear insulating effect of snow, the spatial average ground temperature in a 1 km2 area cannot be determined based on the average snow cover for that area. Land surface or permafrost models employing a coarsely classified average snow depth will therefore not yield a realistic representation of ground temperatures. In this study we employ statistically derived snow distributions within 1 km2 grid cells as input to a regional permafrost model in order to represent sub-grid variability of ground temperatures. This improves the representation of both the average and the total range of ground temperatures. The model reproduces observed sub-grid ground temperature variations of up to 6 °C, and 98 % of borehole observations match the modelled temperature range. The mean modelled temperature of the grid cell reproduces the observations with an accuracy of 1.5 °C or better. The observed sub-grid variations in ground surface temperatures from two field sites are very well reproduced, with estimated fractions of sub-zero mean annual ground surface temperatures within ±10 %. We also find that snow distributions within areas of 1 km2 in Norwegian mountain environments are closer to a gamma than to a lognormal theoretical distribution. The modelled permafrost distribution seems to be more sensitive to the choice of distribution function than to the fine-tuning of the coefficient of variation. When incorporating the small-scale variation of snow, the modelled total permafrost area of mainland Norway is nearly twice as large compared to the area obtained with grid-cell average snow depths without a sub

  12. Spatial variability of soil moisture retrieved by SMOS satellite

    NASA Astrophysics Data System (ADS)

    Lukowski, Mateusz; Marczewski, Wojciech; Usowicz, Boguslaw; Rojek, Edyta; Slominski, Jan; Lipiec, Jerzy

    2015-04-01

    Standard statistical methods assume that the analysed variables are independent. Since the majority of the processes observed in the nature are continuous in space and time, this assumption introduces a significant limitation for understanding the examined phenomena. In classical approach, valuable information about the locations of examined observations is completely lost. However, there is a branch of statistics, called geostatistics, which is the study of random variables, but taking into account the space where they occur. A common example of so-called "regionalized variable" is soil moisture. Using in situ methods it is difficult to estimate soil moisture distribution because it is often significantly diversified. Thanks to the geostatistical methods, by employing semivariance analysis, it is possible to get the information about the nature of spatial dependences and their lengths. Since the Soil Moisture and Ocean Salinity mission launch in 2009, the estimation of soil moisture spatial distribution for regional up to continental scale started to be much easier. In this study, the SMOS L2 data for Central and Eastern Europe were examined. The statistical and geostatistical features of moisture distributions of this area were studied for selected natural soil phenomena for 2010-2014 including: freezing, thawing, rainfalls (wetting), drying and drought. Those soil water "states" were recognized employing ground data from the agro-meteorological network of ground-based stations SWEX and SMUDP2 data from SMOS. After pixel regularization, without any upscaling, the geostatistical methods were applied directly on Discrete Global Grid (15-km resolution) in ISEA 4H9 projection, on which SMOS observations are reported. Analysis of spatial distribution of SMOS soil moisture, carried out for each data set, in most cases did not show significant trends. It was therefore assumed that each of the examined distributions of soil moisture in the adopted scale satisfies

  13. SPATIAL AND TEMPORAL VARIABILITY AND DRIVERS OF NET ECOSYSTEM METABOLISM IN WESTERN GULF OF MEXICO ESTUARIES

    EPA Science Inventory

    Net ecosystem metabolism (NEM) is becoming a commonly used ecological indicator of estuarine ecosystem metabolic rates. Estuarine ecosystem processes are spatially and temporally variable, but the corresponding variability in NEM has not been properly assessed. Spatial and temp...

  14. Small-scale positive flower structures

    NASA Astrophysics Data System (ADS)

    Clendenin, C. W.

    1993-01-01

    Field relations indicate that small-scale positive flower structures along sub-regional strike-slip faults localize ore in particular 4 m thick, bedded ore zones in Mississippi Valley-type Pb-Zn deposits of the Viburnum Trend, southeast Missouri, U.S.A. Outwardly divergent, shallow-dipping, duplex-deformed fault splays control ore and merge inwardly with sub-vertical fault strands. The characteristics of both duplex-deformed splays and ore suggest that the flower structures acted as drains for fluids being moved vertically along the strike-slip faults. This ore control differs from pipe-like conduits of transtensional dilation jogs in that duplex-deformed splays form under transpression and develop horizontal veins adjacent to strike-slip faults.

  15. Controls of Soil Spatial Variability in a Dry Tropical Forest.

    PubMed

    Pulla, Sandeep; Riotte, Jean; Suresh, H S; Dattaraja, H S; Sukumar, Raman

    2016-01-01

    We examined the roles of lithology, topography, vegetation and fire in generating local-scale (<1 km2) soil spatial variability in a seasonally dry tropical forest (SDTF) in southern India. For this, we mapped soil (available nutrients, Al, total C, pH, moisture and texture in the top 10 cm), rock outcrops, topography, all native woody plants ≥1 cm diameter at breast height (DBH), and spatial variation in fire frequency (times burnt during the 17 years preceding soil sampling) in a permanent 50-ha plot. Unlike classic catenas, lower elevation soils had lesser moisture, plant-available Ca, Cu, Mn, Mg, Zn, B, clay and total C. The distribution of plant-available Ca, Cu, Mn and Mg appeared to largely be determined by the whole-rock chemical composition differences between amphibolites and hornblende-biotite gneisses. Amphibolites were associated with summit positions, while gneisses dominated lower elevations, an observation that concurs with other studies in the region which suggest that hillslope-scale topography has been shaped by differential weathering of lithologies. Neither NO3(-)-N nor NH4(+)-N was explained by the basal area of trees belonging to Fabaceae, a family associated with N-fixing species, and no long-term effects of fire on soil parameters were detected. Local-scale lithological variation is an important first-order control over soil variability at the hillslope scale in this SDTF, by both direct influence on nutrient stocks and indirect influence via control of local relief. PMID:27100088

  16. Spatial variability of triazine herbicides in the Lower Mississippi River

    USGS Publications Warehouse

    Moody, J.A.; Goolsby, D.A.

    1993-01-01

    During May 15-17, 1990, an intense rainstorm moved across Iowa, Illinois, Indiana, and Ohio where triazine herbicides are heavily used for growing agricultural crops. Following the storm, the peak concentrations of triazine herbicides in some secondary tributaries to the Upper Mississippi and Ohio Rivers were as high as 36 ??g/L. This runoff water was funneled into the Lower Mississippi River at the Upper Mississippi-Ohio River confluence at Cairo, IL. The spatial variability of this runoff event was measured by collecting midchannel water samples for triazine herbicide analysis from 1 to 2 m below the surface of the Mississippi River every ???16 km from Baton Rouge, LA, upriver to the Mississippi-Ohio River confluence during May 26-29, 1990. All samples were analyzed for triazine herbicides by using an enzyme-linked immunosorbant assay. The results showed a background level of ???2.7 ??g/L, an upriver gradient of 0.2 ??g/L per 100 km, and longitudinal spatial variability that is hypothesized to be the result of cross-channel gradients and "slugs" of water from various upriver tributaries with length scales of 100-150 km and amplitudes of ???1 ??g/L.

  17. Cold dark matter: Controversies on small scales.

    PubMed

    Weinberg, David H; Bullock, James S; Governato, Fabio; Kuzio de Naray, Rachel; Peter, Annika H G

    2015-10-01

    The cold dark matter (CDM) cosmological model has been remarkably successful in explaining cosmic structure over an enormous span of redshift, but it has faced persistent challenges from observations that probe the innermost regions of dark matter halos and the properties of the Milky Way's dwarf galaxy satellites. We review the current observational and theoretical status of these "small-scale controversies." Cosmological simulations that incorporate only gravity and collisionless CDM predict halos with abundant substructure and central densities that are too high to match constraints from galaxy dynamics. The solution could lie in baryonic physics: Recent numerical simulations and analytical models suggest that gravitational potential fluctuations tied to efficient supernova feedback can flatten the central cusps of halos in massive galaxies, and a combination of feedback and low star formation efficiency could explain why most of the dark matter subhalos orbiting the Milky Way do not host visible galaxies. However, it is not clear that this solution can work in the lowest mass galaxies, where discrepancies are observed. Alternatively, the small-scale conflicts could be evidence of more complex physics in the dark sector itself. For example, elastic scattering from strong dark matter self-interactions can alter predicted halo mass profiles, leading to good agreement with observations across a wide range of galaxy mass. Gravitational lensing and dynamical perturbations of tidal streams in the stellar halo provide evidence for an abundant population of low-mass subhalos in accord with CDM predictions. These observational approaches will get more powerful over the next few years. PMID:25646464

  18. Cold dark matter: Controversies on small scales

    PubMed Central

    Weinberg, David H.; Bullock, James S.; Governato, Fabio; Kuzio de Naray, Rachel; Peter, Annika H. G.

    2015-01-01

    The cold dark matter (CDM) cosmological model has been remarkably successful in explaining cosmic structure over an enormous span of redshift, but it has faced persistent challenges from observations that probe the innermost regions of dark matter halos and the properties of the Milky Way’s dwarf galaxy satellites. We review the current observational and theoretical status of these “small-scale controversies.” Cosmological simulations that incorporate only gravity and collisionless CDM predict halos with abundant substructure and central densities that are too high to match constraints from galaxy dynamics. The solution could lie in baryonic physics: Recent numerical simulations and analytical models suggest that gravitational potential fluctuations tied to efficient supernova feedback can flatten the central cusps of halos in massive galaxies, and a combination of feedback and low star formation efficiency could explain why most of the dark matter subhalos orbiting the Milky Way do not host visible galaxies. However, it is not clear that this solution can work in the lowest mass galaxies, where discrepancies are observed. Alternatively, the small-scale conflicts could be evidence of more complex physics in the dark sector itself. For example, elastic scattering from strong dark matter self-interactions can alter predicted halo mass profiles, leading to good agreement with observations across a wide range of galaxy mass. Gravitational lensing and dynamical perturbations of tidal streams in the stellar halo provide evidence for an abundant population of low-mass subhalos in accord with CDM predictions. These observational approaches will get more powerful over the next few years. PMID:25646464

  19. Modeling circulation patterns induced by spatial cross-shore wind variability in a small-size coastal embayment

    NASA Astrophysics Data System (ADS)

    Cerralbo, Pablo; Espino, Manuel; Grifoll, Manel

    2016-08-01

    This contribution shows the importance of the cross-shore spatial wind variability in the water circulation in a small-sized micro-tidal bay. The hydrodynamic wind response at Alfacs Bay (Ebro River delta, NW Mediterranean Sea) is investigated with a numerical model (ROMS) supported by in situ observations. The wind variability observed in meteorological measurements is characterized with meteorological model (WRF) outputs. From the hydrodynamic simulations of the bay, the water circulation response is affected by the cross-shore wind variability, leading to water current structures not observed in the homogeneous-wind case. If the wind heterogeneity response is considered, the water exchange in the longitudinal direction increases significantly, reducing the water exchange time by around 20%. Wind resolutions half the size of the bay (in our case around 9 km) inhibit cross-shore wind variability, which significantly affects the resultant circulation pattern. The characteristic response is also investigated using idealized test cases. These results show how the wind curl contributes to the hydrodynamic response in shallow areas and promotes the exchange between the bay and the open sea. Negative wind curl is related to the formation of an anti-cyclonic gyre at the bay's mouth. Our results highlight the importance of considering appropriate wind resolution even in small-scale domains (such as bays or harbors) to characterize the hydrodynamics, with relevant implications in the water exchange time and the consequent water quality and ecological parameters.

  20. Spatial variability of soils in a seasonally dry tropical forest

    NASA Astrophysics Data System (ADS)

    Pulla, Sandeep; Riotte, Jean; Suresh, Hebbalalu; Dattaraja, Handanakere; Sukumar, Raman

    2016-04-01

    Soil structures communities of plants and soil organisms in tropical forests. Understanding the controls of soil spatial variability can therefore potentially inform efforts towards forest restoration. We studied the relationship between soils and lithology, topography, vegetation and fire in a seasonally dry tropical forest in southern India. We extensively sampled soil (available nutrients, Al, pH, and moisture), rocks, relief, woody vegetation, and spatial variation in fire burn frequency in a permanent 50-ha plot. Lower elevation soils tended to be less moist and were depleted in several nutrients and clay. The availability of several nutrients was, in turn, linked to whole-rock chemical composition differences since some lithologies were associated with higher elevations, while the others tended to dominate lower elevations. We suggest that local-scale topography in this region has been shaped by the spatial distribution of lithologies, which differ in their susceptibility to weathering. Nitrogen availability was uncorrelated with the presence of trees belonging to Fabaceae, a family associated with N-fixing species. No effect of burning on soil parameters could be discerned at this scale.

  1. Variability in Soil Properties at Different Spatial Scales (1 m to 1 km) in a Deciduous Forest Ecosystem

    SciTech Connect

    Garten Jr, Charles T; Kang, S.; Brice, Deanne Jane; Schadt, Christopher Warren; Zhou, Jizhong

    2007-01-01

    The purpose of this research was to test the hypothesis that variability in 11 soil properties, related to soil texture and soil C and N, would increase from small (1 m) to large (1 km) spatial scales in a temperate, mixed-hardwood forest ecosystem in east Tennessee, USA. The results were somewhat surprising and indicated that a fundamental assumption in geospatial analysis, namely that variability increases with increasing spatial scale, did not apply for at least five of the 11 soil properties measured over a 0.5-km2 area. Composite mineral soil samples (15 cm deep) were collected at 1, 5, 10, 50, 250, and 500 m distances from a center point along transects in a north, south, east, and westerly direction. A null hypothesis of equal variance at different spatial scales was rejected (P{le}0.05) for mineral soil C concentration, silt content, and the C-to-N ratios in particulate organic matter (POM), mineral-associated organic matter (MOM), and whole surface soil. Results from different tests of spatial variation, based on coefficients of variation or a Mantel test, led to similar conclusions about measurement variability and geographic distance for eight of the 11 variables examined. Measurements of mineral soil C and N concentrations, C concentrations in MOM, extractable soil NH{sub 4}-N, and clay contents were just as variable at smaller scales (1-10 m) as they were at larger scales (50-500 m). On the other hand, measurement variation in mineral soil C-to-N ratios, MOM C-to-N ratios, and the fraction of soil C in POM clearly increased from smaller to larger spatial scales. With the exception of extractable soil NH4-N, measured soil properties in the forest ecosystem could be estimated (with 95% confidence) to within 15% of their true mean with a relatively modest number of sampling points (n{le}25). For some variables, scaling up variation from smaller to larger spatial domains within the ecosystem could be relatively easy because small-scale variation may be

  2. Modeling temporal and spatial variability of crop yield

    NASA Astrophysics Data System (ADS)

    Bonetti, S.; Manoli, G.; Scudiero, E.; Morari, F.; Putti, M.; Teatini, P.

    2014-12-01

    In a world of increasing food insecurity the development of modeling tools capable of supporting on-farm decision making processes is highly needed to formulate sustainable irrigation practices in order to preserve water resources while maintaining adequate crop yield. The design of these practices starts from the accurate modeling of soil-plant-atmosphere interaction. We present an innovative 3D Soil-Plant model that couples 3D hydrological soil dynamics with a mechanistic description of plant transpiration and photosynthesis, including a crop growth module. Because of its intrinsically three dimensional nature, the model is able to capture spatial and temporal patterns of crop yield over large scales and under various climate and environmental factors. The model is applied to a 25 ha corn field in the Venice coastland, Italy, that has been continuously monitored over the years 2010 and 2012 in terms of both hydrological dynamics and yield mapping. The model results satisfactorily reproduce the large variability observed in maize yield (from 2 to 15 ton/ha). This variability is shown to be connected to the spatial heterogeneities of the farmland, which is characterized by several sandy paleo-channels crossing organic-rich silty soils. Salt contamination of soils and groundwater in a large portion of the area strongly affects the crop yield, especially outside the paleo-channels, where measured salt concentrations are lower than the surroundings. The developed model includes a simplified description of the effects of salt concentration in soil water on transpiration. The results seem to capture accurately the effects of salt concentration and the variability of the climatic conditions occurred during the three years of measurements. This innovative modeling framework paves the way to future large scale simulations of farmland dynamics.

  3. Models of Small-Scale Patchiness

    NASA Technical Reports Server (NTRS)

    McGillicuddy, D. J.

    2001-01-01

    Patchiness is perhaps the most salient characteristic of plankton populations in the ocean. The scale of this heterogeneity spans many orders of magnitude in its spatial extent, ranging from planetary down to microscale. It has been argued that patchiness plays a fundamental role in the functioning of marine ecosystems, insofar as the mean conditions may not reflect the environment to which organisms are adapted. Understanding the nature of this patchiness is thus one of the major challenges of oceanographic ecology. The patchiness problem is fundamentally one of physical-biological-chemical interactions. This interconnection arises from three basic sources: (1) ocean currents continually redistribute dissolved and suspended constituents by advection; (2) space-time fluctuations in the flows themselves impact biological and chemical processes, and (3) organisms are capable of directed motion through the water. This tripartite linkage poses a difficult challenge to understanding oceanic ecosystems: differentiation between the three sources of variability requires accurate assessment of property distributions in space and time, in addition to detailed knowledge of organismal repertoires and the processes by which ambient conditions control the rates of biological and chemical reactions. Various methods of observing the ocean tend to lie parallel to the axes of the space/time domain in which these physical-biological-chemical interactions take place. Given that a purely observational approach to the patchiness problem is not tractable with finite resources, the coupling of models with observations offers an alternative which provides a context for synthesis of sparse data with articulations of fundamental principles assumed to govern functionality of the system. In a sense, models can be used to fill the gaps in the space/time domain, yielding a framework for exploring the controls on spatially and temporally intermittent processes. The following discussion highlights

  4. Spatial variability in plant species composition and peatland carbon exchange

    NASA Astrophysics Data System (ADS)

    Goud, E.; Moore, T. R.; Roulet, N. T.

    2015-12-01

    Plant species shifts in response to global change will have significant impacts on ecosystem carbon (C) exchange and storage arising from changes in hydrology. Spatial variation in peatland C fluxes have largely been attributed to the spatial distribution of microhabitats that arise from variation in surface topography and water table depth, but little is known about how plant species composition impacts peatland C cycling or how these impacts will be influenced by changing environmental conditions. We quantified the effect of species composition and environmental variables on carbon dioxide (CO2) and methane (CH4) fluxes over 2 years in a temperate peatland for four plant communities situated along a water table gradient from ombrotrophic bog to beaver pond. We hypothesized that (i) spatial heterogeneity in species composition would drive predictable spatial heterogeneity in C fluxes due to variation in plant traits and ecological tolerances, and (ii) increases in peat temperature would increase C fluxes. Species had different effects on C fluxes primarily due to differences in leaf traits. Differences in ecological tolerances among communities resulted in different rates of CO2 exchange in response to changes in water table depth. There was an overall reduction in ecosystem respiration (ER), gross primary productivity (GPP) and CH4 flux in response to colder peat temperatures in the second year, and the additive effects of a deeper water table in the bog margin and pond sites further reduced flux rates in these areas. These results demonstrate that different plant species can increase or decrease the flux of C into and out of peatlands based on differences in leaf traits and ecological tolerances, and that CO2 and CH4 fluxes are sensitive to changes in soil temperature, especially when coupled with changes in moisture availability.

  5. Economic analysis of small-scale fuel alcohol plants

    SciTech Connect

    Schafer, J.J. Jr.

    1980-01-01

    To plan Department of Energy support programs, it is essential to understand the fundamental economics of both the large industrial size plants and the small on-farm size alcohol plants. EG and G Idaho, Inc., has designed a 25 gallon per hour anhydrous ethanol plant for the Department of Energy's Alcohol Fuels Office. This is a state-of-the-art reference plant, which will demonstrate the cost and performance of currently available equipment. The objective of this report is to examine the economics of the EG and G small-scale alcohol plant design and to determine the conditions under which a farm plant is a financially sound investment. The reference EG and G Small-Scale Plant is estimated to cost $400,000. Given the baseline conditions defined in this report, it is calculated that this plant will provide an annual after-tax of return on equity of 15%, with alcohol selling at $1.62 per gallon. It is concluded that this plant is an excellent investment in today's market, where 200 proof ethanol sells for between $1.80 and $2.00 per gallon. The baseline conditions which have a significant effect on the economics include plant design parameters, cost estimates, financial assumptions and economic forecasts. Uncertainty associated with operational variables will be eliminated when EG and G's reference plant begins operation in the fall of 1980. Plant operation will verify alcohol yield per bushel of corn, labor costs, maintenance costs, plant availability and by-product value.

  6. Preferential Sampling and Small-Scale Clustering of Gyrotactic Microswimmers in Turbulence.

    PubMed

    Gustavsson, K; Berglund, F; Jonsson, P R; Mehlig, B

    2016-03-11

    Recent studies show that spherical motile microorganisms in turbulence subject to gravitational torques gather in down-welling regions of the turbulent flow. By analyzing a statistical model we analytically compute how shape affects the dynamics, preferential sampling, and small-scale spatial clustering. We find that oblong organisms may spend more time in up-welling regions of the flow, and that all organisms are biased to regions of positive fluid-velocity gradients in the upward direction. We analyze small-scale spatial clustering and find that oblong particles may either cluster more or less than spherical ones, depending on the strength of the gravitational torques. PMID:27015512

  7. Preferential Sampling and Small-Scale Clustering of Gyrotactic Microswimmers in Turbulence

    NASA Astrophysics Data System (ADS)

    Gustavsson, K.; Berglund, F.; Jonsson, P. R.; Mehlig, B.

    2016-03-01

    Recent studies show that spherical motile microorganisms in turbulence subject to gravitational torques gather in down-welling regions of the turbulent flow. By analyzing a statistical model we analytically compute how shape affects the dynamics, preferential sampling, and small-scale spatial clustering. We find that oblong organisms may spend more time in up-welling regions of the flow, and that all organisms are biased to regions of positive fluid-velocity gradients in the upward direction. We analyze small-scale spatial clustering and find that oblong particles may either cluster more or less than spherical ones, depending on the strength of the gravitational torques.

  8. Spatial and temporal variability of clouds and precipitation over Germany: multiscale simulations across the "gray zone"

    NASA Astrophysics Data System (ADS)

    Barthlott, C.; Hoose, C.

    2015-11-01

    This paper assesses the resolution dependance of clouds and precipitation over Germany by numerical simulations with the COnsortium for Small-scale MOdeling (COSMO) model. Six intensive observation periods of the HOPE (HD(CP)2 Observational Prototype Experiment) measurement campaign conducted in spring 2013 and 1 summer day of the same year are simulated. By means of a series of grid-refinement resolution tests (horizontal grid spacing 2.8, 1 km, 500, and 250 m), the applicability of the COSMO model to represent real weather events in the gray zone, i.e., the scale ranging between the mesoscale limit (no turbulence resolved) and the large-eddy simulation limit (energy-containing turbulence resolved), is tested. To the authors' knowledge, this paper presents the first non-idealized COSMO simulations in the peer-reviewed literature at the 250-500 m scale. It is found that the kinetic energy spectra derived from model output show the expected -5/3 slope, as well as a dependency on model resolution, and that the effective resolution lies between 6 and 7 times the nominal resolution. Although the representation of a number of processes is enhanced with resolution (e.g., boundary-layer thermals, low-level convergence zones, gravity waves), their influence on the temporal evolution of precipitation is rather weak. However, rain intensities vary with resolution, leading to differences in the total rain amount of up to +48 %. Furthermore, the location of rain is similar for the springtime cases with moderate and strong synoptic forcing, whereas significant differences are obtained for the summertime case with air mass convection. Domain-averaged liquid water paths and cloud condensate profiles are used to analyze the temporal and spatial variability of the simulated clouds. Finally, probability density functions of convection-related parameters are analyzed to investigate their dependance on model resolution and their impact on cloud formation and subsequent precipitation.

  9. [Temporal and spatial variability of livestock and poultry productions and manure nutrients in Shanxi Province, China].

    PubMed

    Zhang, Jian-jie; Guo, Cai-xia; Qin, Wei; Zhang, Qiang

    2016-01-01

    China's livestock and poultry productions have changed significantly in the last three decades, from mainly traditional and small-scale systems in early 1980s towards more intensive and industrialized ones in recent years, due to the booming economy and the changes in people' diet. There is an urgent need to increase the understanding of the changes in the livestock and poultry productions and the impact of manure recycle on the environment. Here, we reported on a systematic and quantitative analysis on the temporal and spatial variability of livestock and poultry productions and manure nutrients in Shanxi Province, China, using a large database and a coupled food chain nutrient flow model (NUFER) with GIS. In the period of 1978 to 2012, total animal manure production increased from 1.61 x 10⁷ t to 2.75 x 10⁷ t by 171%. The manure N increased from 7.74 x 10⁴ t to 17.32 x 10⁴ t, and the manure P from 1.09x104 t to 3.39x104 t. Besides the huge increase in total animal manure production, the distribution of animal manure was much uneven among regions, with high amounts of manure N and P per unit land in the north, middle and southeastern regions and low values in the north-central and southwestern regions, based on the results of 2012. The uneven distribution of manure was the combined effect of regional specializations in livestock and poultry productions and related policies. Our findings suggested that optimizing the structure of livestock and poultry productions and enhancing interregional collaborations on nutrient management could be two effective measures for reducing pollution and environmental risks, while achieving efficient and sustainable use of manure nutrient in the long term. PMID:27228611

  10. Controls of Soil Spatial Variability in a Dry Tropical Forest

    PubMed Central

    Pulla, Sandeep; Riotte, Jean; Suresh, H. S.; Dattaraja, H. S.; Sukumar, Raman

    2016-01-01

    We examined the roles of lithology, topography, vegetation and fire in generating local-scale (<1 km2) soil spatial variability in a seasonally dry tropical forest (SDTF) in southern India. For this, we mapped soil (available nutrients, Al, total C, pH, moisture and texture in the top 10cm), rock outcrops, topography, all native woody plants ≥1 cm diameter at breast height (DBH), and spatial variation in fire frequency (times burnt during the 17 years preceding soil sampling) in a permanent 50-ha plot. Unlike classic catenas, lower elevation soils had lesser moisture, plant-available Ca, Cu, Mn, Mg, Zn, B, clay and total C. The distribution of plant-available Ca, Cu, Mn and Mg appeared to largely be determined by the whole-rock chemical composition differences between amphibolites and hornblende-biotite gneisses. Amphibolites were associated with summit positions, while gneisses dominated lower elevations, an observation that concurs with other studies in the region which suggest that hillslope-scale topography has been shaped by differential weathering of lithologies. Neither NO3−-N nor NH4+-N was explained by the basal area of trees belonging to Fabaceae, a family associated with N-fixing species, and no long-term effects of fire on soil parameters were detected. Local-scale lithological variation is an important first-order control over soil variability at the hillslope scale in this SDTF, by both direct influence on nutrient stocks and indirect influence via control of local relief. PMID:27100088

  11. Determining the spatial variability of personal sampler inlet locations

    SciTech Connect

    Vinson, R.; Volkwein, J.; Mcwilliams, L.

    2007-09-15

    This article examines the spatial variability of dust concentrations within a coal miner's breathing zone and the impact of sampling location at the cap lamp, nose, and lapel. Tests were conducted in the National Institute for Safety and Health Pittsburgh Research Laboratory full-scale, continuous miner gallery using three prototype personal dust monitors (PDM). The dust masses detected by the PDMs were used to calculate the percentage difference of dust mass between the cap lamp and the nose and between the lapel and the nose. The calculated percentage differences of the masses ranged from plus 12% to minus 25%. Breathing zone tests were also conducted in four underground coal mines using the torso of a mannequin to simulate a miner. Coal mine dust was sampled with multi-cyclone sampling cans mounted directly in front of the mannequin near the cap lamp, nose, and lapel. These four coal mine tests found that the spatial variability of dust levels and imprecision of the current personal sampler is a greater influence than the sampler location within the breathing zone. However, a one-sample t-test of this data did find that the overall mean value of the cap lamp/nose ratio was not significantly different than 1 (p-value = 0.21). However; when applied to the overall mean value of the lapel/nose ratio there was a significant difference from 1 (p-value < 0.0001). This finding is important because the lapel has always been the sampling location for coal mine dust samples. But these results suggest that the cap location is slightly more indicative of what is breathed through the nose area.

  12. Hypsometric analysis to identify spatially variable glacial erosion

    NASA Astrophysics Data System (ADS)

    Sternai, P.; Herman, F.; Fox, M. R.; Castelltort, S.

    2011-09-01

    Relatively little research has been undertaken on the use of digital elevation models to recognize the spatially variable glacial imprint of a landscape. Using theoretical topographies and a landscape evolution model, we investigate to what extent the hypsometric analysis of digital elevation models may be used to recognize the glacial signature of mountain ranges. A new morphometric parameter, which we term the hypsokyrtome (from the Greek: ipsos = elevation, kyrtoma = curvature), is derived from the gradient of the hypsometric curve. The efficacy of the hypsometric integral and hypsokyrtome is tested through the study of the Ben Ohau Range, New Zealand, whose glacial imprint has been described previously. With a numerical model we further test the geomorphic parameters in describing the morphologies of regions subject to diverse climatic and tectonic conditions. The hypsokyrtome is highly sensitive to glacial erosion, and the maps produced provide insights into the spatial distribution of glacial erosion. We use SRTM data and focus on two alternative geomorphic settings: the European Alps and the Apennines. The former has been affected by both fluvial and glacial erosion while the latter mainly exhibits a fluvially dominated morphology. The correlation between elevations with increased glacial erosion and Last Glacial Maximum (LGM) equilibrium line altitudes (ELAs) suggests the prevalence of a "glacial buzz saw" in the Alps, indicating that climate may put a limit on alpine topography.

  13. Small-scale dynamic confinement gap test

    NASA Astrophysics Data System (ADS)

    Cook, Malcolm

    2011-06-01

    Gap tests are routinely used to ascertain the shock sensitiveness of new explosive formulations. The tests are popular since that are easy and relatively cheap to perform. However, with modern insensitive formulations with big critical diameters, large test samples are required. This can make testing and screening of new formulations expensive since large quantities of test material are required. Thus a new test that uses significantly smaller sample quantities would be very beneficial. In this paper we describe a new small-scale test that has been designed using our CHARM ignition and growth routine in the DYNA2D hydrocode. The new test is a modified gap test and uses detonating nitromethane to provide dynamic confinement (instead of a thick metal case) whilst exposing the sample to a long duration shock wave. The long duration shock wave allows less reactive materials that are below their critical diameter, more time to react. We present details on the modelling of the test together with some preliminary experiments to demonstrate the potential of the new test method.

  14. Hoopa Valley Small Scale Hydroelectric Feasibility Project

    SciTech Connect

    Curtis Miller

    2009-03-22

    This study considered assessing the feasibility of developing small scale hydro-electric power from seven major tributaries within the Hoopa Valley Indian Reservation of Northern California (http://www.hoopa-nsn.gov/). This study pursued the assessment of seven major tributaries of the Reservation that flow into the Trinity River. The feasibility of hydropower on the Hoopa Valley Indian Reservation has real potential for development and many alternative options for project locations, designs, operations and financing. In order to realize this opportunity further will require at least 2-3 years of intense data collection focusing on stream flow measurements at multiple locations in order to quantify real power potential. This also includes on the ground stream gradient surveys, road access planning and grid connectivity to PG&E for sale of electricity. Imperative to this effort is the need for negotiations between the Hoopa Tribal Council and PG&E to take place in order to finalize the power rate the Tribe will receive through any wholesale agreement that utilizes the alternative energy generated on the Reservation.

  15. Slip Dynamics in Small Scale Crystals

    NASA Astrophysics Data System (ADS)

    Maass, Robert; Derlet, Peter; Greer, Julia; Volkert, Cynthia

    2015-03-01

    Classical work showed that dislocation velocities are strongly dependent on applied stress. Numerous experiments have validated this for individual or groups of dislocations in macroscopic crystals by using imaging techniques combined with either mechanical data or time resolved topological data. Developments in small scale mechanical testing allow to correlate the intermittency of collective dislocation motion with the mechanical response. Discrete forward surges in displacement can be related to dislocation avalanches, which are triggered by the evolving dislocation sub-structure. We study the spatiotemporal characteristics of intermittent plastic flow in quasi-statically sheared single crystalline Au crystals with diameters between 300 nm and 10000 nm, whose displacement bursts were recorded at several kHz (Scripta Mater. 2013, 69, 586; Small, available online). Both the crystallographic slip magnitude, as well as the velocity of the slip events are exhibiting power-law scaling as. The obtained slip velocity distribution has a cubic decay at high values, and a saturated flat shoulder at lower velocities. No correlation between the slip velocity and the applied stress or plastic strain is found. Further, we present DD-simulations that are supportive of our experimental findings. The simulations suggest that the dynamics of the internal stress fields dominate the evolving dislocation structure leading to velocities that are insensitive to the applied stress - a regime indicative of microplasticity.

  16. Spatial Variability of Electrical Conductivity in North Mississippi Loamy Soils

    NASA Astrophysics Data System (ADS)

    Twombly, J. E.; Fancher, C. W.; Sleep, M. D.; Aufman, M. S.; Holland, J. V.; Holt, R. M.; Kuszmaul, J. S.

    2004-05-01

    The use of non-contact electrical geophysical methods, such as electromagnetic induction (EM), to characterize and quantify spatial and temporal variations in soil properties is appealing due to low operational costs, rapid measurements, and device mobility. These methods are sensitive to soil electrical conductivity, which can vary with soil moisture, clay content, soil salinity, and the presence of electrically conductive minerals. We conducted a preliminary study to evaluate the controls on EM response in loamy soils present at the University of Mississippi (UM) Soil Moisture Observatory (SMO). The 5 acre SMO is located in a former agricultural field at the UM Biological Field Station, a 740 acre tract of land located 11 miles from the UM campus in Oxford, Mississippi. EM responses were surveyed along two intersecting transects using a Geonics EM38. The apparent electrical conductivity (EC) of the soil was determined in both a vertical and horizontal dipole position, which correspond to deep (~1m) and shallow (~0.5) measurements, respectively. Continuous soil samples were recovered from the transect points and analyzed for soil properties. Except for a weak negative correlation with moisture content, we found little direct correlation between EC and measured soil properties. EC variograms from surveys conducted on different dates consistently show a similar structure. Following a week of rain, three EM 38 surveys were conducted, each a week apart. During this survey period, a nearby meteorological station reported no significant precipitation, and the soils were drying. All EC variograms show similar spatial structures but decreasing amounts of variability consistent with drying and redistribution of soil moisture. These results suggest that soil physical properties, not soil moisture, control the spatial distribution of EC. Temporal variations in the variograms indicate a complex relationship between soil moisture and EC.

  17. Experimental, theoretical, and numerical studies of small scale combustion

    NASA Astrophysics Data System (ADS)

    Xu, Bo

    Recently, the demand increased for the development of microdevices such as microsatellites, microaerial vehicles, micro reactors, and micro power generators. To meet those demands the biggest challenge is obtaining stable and complete combustion at relatively small scale. To gain a fundamental understanding of small scale combustion in this thesis, thermal and kinetic coupling between the gas phase and the structure at meso and micro scales were theoretically, experimentally, and numerically studied; new stabilization and instability phenomena were identified; and new theories for the dynamic mechanisms of small scale combustion were developed. The reduction of thermal inertia at small scale significantly reduces the response time of the wall and leads to a strong flame-wall coupling and extension of burning limits. Mesoscale flame propagation and extinction in small quartz tubes were theoretically, experimentally and numerically studied. It was found that wall-flame interaction in mesoscale combustion led to two different flame regimes, a heat-loss dominant fast flame regime and a wall-flame coupling slow flame regime. The nonlinear transition between the two flame regimes was strongly dependent on the channel width and flow velocity. It is concluded that the existence of multiple flame regimes is an inherent phenomenon in mesoscale combustion. In addition, all practical combustors have variable channel width in the direction of flame propagation. Quasi-steady and unsteady propagations of methane and propane-air premixed flames in a mesoscale divergent channel were investigated experimentally and theoretically. The emphasis was the impact of variable cross-section area and the flame-wall coupling on the flame transition between different regimes and the onset of flame instability. For the first time, spinning flames were experimentally observed for both lean and rich methane and propane-air mixtures in a broad range of equivalence ratios. An effective Lewis number

  18. TURBULENT SMALL-SCALE DYNAMO ACTION IN SOLAR SURFACE SIMULATIONS

    SciTech Connect

    Graham, Jonathan Pietarila; Cameron, Robert; Schuessler, Manfred

    2010-05-10

    We demonstrate that a magneto-convection simulation incorporating essential physical processes governing solar surface convection exhibits turbulent small-scale dynamo action. By presenting a derivation of the energy balance equation and transfer functions for compressible magnetohydrodynamics, we quantify the source of magnetic energy on a scale-by-scale basis. We rule out the two alternative mechanisms for the generation of the small-scale magnetic field in the simulations: the tangling of magnetic field lines associated with the turbulent cascade and Alfvenization of small-scale velocity fluctuations ('turbulent induction'). Instead, we find that the dominant source of small-scale magnetic energy is stretching by inertial-range fluid motions of small-scale magnetic field lines against the magnetic tension force to produce (against Ohmic dissipation) more small-scale magnetic field. The scales involved become smaller with increasing Reynolds number, which identifies the dynamo as a small-scale turbulent dynamo.

  19. Hierarchical Multiscale Adaptive Variable Fidelity Wavelet-based Turbulence Modeling with Lagrangian Spatially Variable Thresholding

    NASA Astrophysics Data System (ADS)

    Nejadmalayeri, Alireza

    The current work develops a wavelet-based adaptive variable fidelity approach that integrates Wavelet-based Direct Numerical Simulation (WDNS), Coherent Vortex Simulations (CVS), and Stochastic Coherent Adaptive Large Eddy Simulations (SCALES). The proposed methodology employs the notion of spatially and temporarily varying wavelet thresholding combined with hierarchical wavelet-based turbulence modeling. The transition between WDNS, CVS, and SCALES regimes is achieved through two-way physics-based feedback between the modeled SGS dissipation (or other dynamically important physical quantity) and the spatial resolution. The feedback is based on spatio-temporal variation of the wavelet threshold, where the thresholding level is adjusted on the fly depending on the deviation of local significant SGS dissipation from the user prescribed level. This strategy overcomes a major limitation for all previously existing wavelet-based multi-resolution schemes: the global thresholding criterion, which does not fully utilize the spatial/temporal intermittency of the turbulent flow. Hence, the aforementioned concept of physics-based spatially variable thresholding in the context of wavelet-based numerical techniques for solving PDEs is established. The procedure consists of tracking the wavelet thresholding-factor within a Lagrangian frame by exploiting a Lagrangian Path-Line Diffusive Averaging approach based on either linear averaging along characteristics or direct solution of the evolution equation. This innovative technique represents a framework of continuously variable fidelity wavelet-based space/time/model-form adaptive multiscale methodology. This methodology has been tested and has provided very promising results on a benchmark with time-varying user prescribed level of SGS dissipation. In addition, a longtime effort to develop a novel parallel adaptive wavelet collocation method for numerical solution of PDEs has been completed during the course of the current work

  20. Spatial and temporal variability of Antarctic precipitation from atmospheric methods

    SciTech Connect

    Cullather, R.L.; Bromwich, D.H.; Van Woert, M.L.

    1998-03-01

    The spatial and temporal variability of net precipitation (precipitation minus evaporation/sublimation) for Antarctica derived from the European Centre for Medium-Range Weather Forecasts operational analyses via the atmospheric moisture budget is assessed in comparison to a variety of glaciological and meteorological observations and datasets. For the 11-yr period 1985-95, the average continental value is 151 mm yr{sup {minus}1} water equivalent. Large regional differences with other datasets are identified, and the sources of error are considered. Interannual variability in the Southern Ocean storm tracks is found to be an important mechanism for enhanced precipitation minus evaporation (P-E) in both east and west Antarctica. In relation to the present findings, an evaluation of the rawinsonde method for estimating net precipitation in east Antarctica is conducted. Estimates of P-E using synthetic rawinsondes derived from the analyses are found to compare favorably to glaciological estimates. A significant upward trend of 2.4 mm yr{sup {minus}1} is found for the Antarctic continent that is consistent with findings from the National Centers for Environmental Prediction, formerly the National Meteorological Center, and the National Center for Atmospheric Research Reanalysis precipitation dataset. Despite large regional discrepancies, the general agreement on the main features of Antarctic precipitation between studies suggests that a threshold has been reached, where the assessment of the smaller terms including evaporation/sublimation and drift snow loss is required to explain the differences. 76 refs., 24 figs., 1 tab.

  1. Spatial variability of snow physical properties across northwestern Greenland

    NASA Astrophysics Data System (ADS)

    Courville, Z.; Polashenski, C.; Dibb, J. E.; Domine, F.

    2013-12-01

    In the late spring and early summer of 2013, researchers on the SAGE (Sunlight Absorption on the Greenland ice sheet Experiment) Traverse, embarked on a 4000 km ground traverse across northwestern Greenland in an attempt to quantify spatial variability of snow chemistry, snow physical properties, and snow reflectance. The field team targeted sites first visited by Carl Benson during his series of traverses from 1952 to 1955 as part of his pioneering work to characterize the Greenland Ice Sheet. This route now represents a rapidly changing and variable area of Greenland, as the route passes through several of the ice sheet facies first delimited by Benson. Along the traverse, the SAGE field team made ground-based albedo measurements using a hand-held spectroradiometer and collected snow physical property samples to determine snow specific surface area (SSA) from shallow, 2m pits. In addition, snow density and stratigraphy were measured. Snow layers in the near-surface and at the previous season's melt layer were targeted for sampling. Here we present preliminary snow physical property results from the upper portion of the snow pits and relate these to surface albedo data collected over the route. Further measurements of snow properties in the 2012 melt layer will be analyzed to assess the potential role of snow chemical (see Dibb et al. for a discussion of chemical analysis) and physical property driven albedo feedbacks could have played in contributing to that event. Route of 2013 SAGE Traverse in northwestern Greenland.

  2. Mapping Spatial Variability in Health and Wealth Indicators in Accra, Ghana Using High Spatial Resolution Imagery

    NASA Astrophysics Data System (ADS)

    Engstrom, R.; Ashcroft, E.

    2014-12-01

    There has been a tremendous amount of research conducted that examines disparities in health and wealth of persons between urban and rural areas however, relatively little research has been undertaken to examine variations within urban areas. A major limitation to elucidating differences with urban areas is the lack of social and demographic data at a sufficiently high spatial resolution to determine these differences. Generally the only available data that contain this information are census data which are collected at most every ten years and are often difficult to obtain at a high enough spatial resolution to allow for examining in depth variability in health and wealth indicators at high spatial resolutions, especially in developing countries. High spatial resolution satellite imagery may be able to provide timely and synoptic information that is related to health and wealth variability within a city. In this study we use two dates of Quickbird imagery (2003 and 2010) classified into the vegetation-impervious surface-soil (VIS) model introduced by Ridd (1995). For 2003 we only have partial coverage of the city, while for 2010 we have a mosaic, which covers the entire city of Accra, Ghana. Variations in the VIS values represent the physical variations within the city and these are compared to variations in economic, and/or sociodemographic data derived from the 2000 Ghanaian census at two spatial resolutions, the enumeration area (approximately US Census Tract) and the neighborhood for the city. Results indicate a significant correlation between both vegetation and impervious surface to type of cooking fuel used in the household, population density, housing density, availability of sewers, cooking space usage, and other variables. The correlations are generally stronger at the neighborhood level and the relationships are stable through time and space. Overall, the results indicate that information derived from high resolution satellite data is related to

  3. Spatial and temporal variability of Mediterranean drought events

    NASA Astrophysics Data System (ADS)

    Trigo, R.; Sousa, P.; Nieto, R.; Gimeno, L.

    2009-04-01

    The original Palmer Drought Severity Index (PDSI) and a recent adaptation to European soil characteristics, the Self Calibrated PDSI (or scPDSI) proposed by Schrier et al (2005) were used. We have computed monthly, seasonal and annual trends between 1901 and 2000 but also for the first and second halves of the 20th century. Results were represented only when achieving a minimum level of statistical significance (either 5% or 10% using a Mann-Kendall test) and confirm that the majority of the western and central Mediterranean is getting drier in the last decades of the 20th century while Turkey is generally getting wetter (Trigo et al., 2006). The spatio-temporal variability of these indices was evaluated with an EOF analysis, in order to reduce the large dimensionality of the fields under analysis. Spatial representation of the first EOF patterns shows that EOF 1 covers the entire Mediterranean basin (16.4% of EV), while EOF2 is dominated by a W-E dipole (10% EV). The following EOF patterns present smaller scale features, and explain smaller amounts of variance. The EOF patterns have also facilitated the definition of four sub-regions with large socio-economic relevance: 1) Iberia, 2) Italian Peninsula, 3) Balkans and 4) Turkey. The inter-annual variability of the regional spatial droughts indices for each region was analyzed separately. We have also performed an evaluation of their eventual links with large-scale atmospheric circulation indices that affect the Mediterranean basin, namely the NAO, EA, and SCAND. Finally we have evaluated the main sources of moisture affecting two drought prone areas in the western (Iberia) and eastern (Balkans) Mediterranean. This analysis was performed by means of backward tracking the air masses that ultimately reach these two regions using the Lagrangian particle dispersion model FLEXPART (Stohl et al., 1998) and meteorological analysis data from the ECMWF to track atmospheric moisture. This was done for a five-year period (2000

  4. Spatial and temporal variability of rainfall in the Nile Basin

    NASA Astrophysics Data System (ADS)

    Onyutha, C.; Willems, P.

    2015-05-01

    Spatiotemporal variability in annual and seasonal rainfall totals were assessed at 37 locations of the Nile Basin in Africa using quantile perturbation method (QPM). To get insight into the spatial difference in rainfall statistics, the stations were grouped based on the pattern of the long-term mean (LTM) of monthly rainfall and that of temporal variability. To find the origin of the driving forces for the temporal variability in rainfall, correlation analyses were carried out using global monthly sea level pressure (SLP) and sea surface temperature (SST). Further investigations to support the obtained correlations were made using a total of 10 climate indices. It was possible to obtain three groups of stations; those within the equatorial region (A), Sudan and Ethiopia (B), and Egypt (C). For group A, annual rainfall was found to be below (above) the reference during the late 1940s to 1950s (1960s to mid-1980s). Conversely for groups B and C, the period from 1930s to late 1950s (1960s to 1980s) was characterized by anomalies being above (below) the reference. For group A, significant linkages were found to Niño 3, Niño 3.4, and the North Atlantic Ocean and Indian Ocean drivers. Correlations of annual rainfall of group A with Pacific Ocean-related climate indices were inconclusive. With respect to the main wet seasons, the June-September rainfall of group B has strong connection to the influence from the Indian Ocean. For the March-May (October-February) rainfall of group A (C), possible links to the Atlantic and Indian oceans were found.

  5. Spatial and temporal variability of rainfall in the Nile Basin

    NASA Astrophysics Data System (ADS)

    Onyutha, C.; Willems, P.

    2014-10-01

    Spatio-temporal variability in annual and seasonal rainfall totals were assessed at 37 locations of the Nile Basin in Africa using quantile perturbation method. To get insight into the spatial difference in rainfall statistics, the stations were grouped based on the pattern of the long-term mean of monthly rainfall and that of temporal variability. To find the origin of the driving forces for the temporal variability in rainfall, correlation analyses were carried out using global monthly sea level pressure and surface temperature. Further investigations to support the obtained correlations were made using a total of 10 climate indices. It was possible to obtain 3 groups of stations; those within the equatorial region (A), Sudan and Ethiopia (B), and Egypt (C). For group A, annual rainfall was found to be below (above) the reference during the late 1940s to 1950s (1960s to mid 1980s). Conversely for groups B and C, the period 1930s to late 1950s (1960s to 1980s) was characterized by anomalies being above (below) the reference. For group A, significant linkages were found to Niño 3, Niño 3.4 and the North Atlantic and Indian Ocean drivers. Correlations of annual rainfall of group A with Pacific Ocean-related climate indices were inconclusive. With respect to the main wet seasons, the June to September rainfall of group B has strong connection to the influence from the Indian Ocean. For the March to May (October to February) rainfall of group A (C), possible links to the Atlantic and Indian Oceans were found.

  6. Small-scale upper mantle extension beneath a destroyed craton

    NASA Astrophysics Data System (ADS)

    Zhao, L.; Zheng, T.; Chen, L.; Ai, Y.; He, Y.; Xu, X.

    2014-12-01

    also show changes with spatially coherency. This consistency in small-scale variations through the crust to the upper mantle implies coupled pattern of deformation at the lithospheric scale of the NCC, and possibly reflects the dominant effect of small-scale mantle flow during the cratonic reactivation in the north edge of the NCC.

  7. Small-scale nonlinear dynamics of K-mouflage theories

    NASA Astrophysics Data System (ADS)

    Brax, Philippe; Valageas, Patrick

    2014-12-01

    We investigate the small-scale static configurations of K-mouflage models defined by a general function K (χ ) of the kinetic terms. The fifth force is screened by the nonlinear K-mouflage mechanism if K'(χ ) grows sufficiently fast for large negative χ . In the general nonspherically symmetric case, the fifth force is not aligned with the Newtonian force. For spherically symmetric static matter density profiles, we show that the results depend on the potential function W-(y )=y K'(-y2/2 ) ; i.e., W-(y ) must be monotonically increasing to +∞ for y ≥0 to guarantee the existence of a single solution throughout space for any matter density profile. Small radial perturbations around these static profiles propagate as travelling waves with a velocity greater than the speed of light. Starting from vanishing initial conditions for the scalar field and for a time-dependent matter density corresponding to the formation of an overdensity, we numerically check that the scalar field converges to the static solution. If W- is bounded, for high-density objects there are no static solutions throughout space, but one can still define a static solution restricted to large radii. Our dynamical study shows that the scalar field relaxes to this static solution at large radii, whereas spatial gradients keep growing with time at smaller radii. If W- is not bounded but nonmonotonic, there is an infinite number of discontinuous static solutions. However, the Klein-Gordon equation is no longer a well-defined hyperbolic equation, which leads to complex characteristic speeds and exponential instabilities. Therefore, these discontinuous static solutions are not physical, and these models are not theoretically sound. Such K-mouflage scenarios provide an example of theories that can appear viable at the cosmological level, for the cosmological background and perturbative analysis, while being meaningless at a nonlinear level for small-scale configurations. This shows the importance of

  8. Spatial variability of absorption properties in Lake Balaton, Hungary

    NASA Astrophysics Data System (ADS)

    Riddick, C. A.; Hunter, P. D.; Tyler, A. N.; Vicente, V. M.; Groom, S.; Horváth, H.; Kovacs, A.; Preston, T.; Presing, M.

    2013-12-01

    In order to improve robustness of current remote sensing algorithms for lake monitoring, it is vital to understand the variability of inherent optical properties (IOPs) within a lake. In this study, absorption coefficients were measured in situ at 38 stations in Lake Balaton, Hungary, using a WET Labs AC-S and AC-9 and compared to concurrent absorption measurements by dual beam spectrophotometry in the laboratory. The spatial variability of bulk and chlorophyll-specific absorption coefficients was examined across 5 basins, demonstrating a gradient in total absorption corresponding to the trophic gradient. Our data suggests that sampling conditions had an impact on particulate absorption, affecting the proportion attributed to non-algal particles (aNAP), phytoplankton (aph) or color dissolved organic matter (aCDOM). The specific absorption of phytoplankton (a*ph) spectra showed a distinct peak in the UV portion of the spectra in Basins 3 and 4 (east), which may be due to the presence of phytoplankton photoprotective pigments to compensate for lower CDOM levels in these basins. In contrast to oceans, particulate attenuation (cp) had a weaker relationship to chlorophyll-a (R2=0.15) than to total suspended matter (R2=0.84), particularly the inorganic fraction. Additionally, the relative contribution of particulate scattering (bp) to attenuation was significantly higher in Lake Balaton (up to 85-99%) than that found in previous lacustrine studies. bp also demonstrated a gradient across the lake, where values increased as the water progressed from phytoplankton-dominated to mineral-dominated. These results provide knowledge of the heterogeneity of the IOPs within Lake Balaton, which is to be considered for the future improvement of bio-optical algorithms for constituent retrieval in inland waters.

  9. Spatial and temporal variability of the precipitation seasonality

    NASA Astrophysics Data System (ADS)

    Baciu, Madalina; Cheval, Sorin; Dumitrescu, Alexandru; Breza, Traian

    2014-05-01

    Climate change scenarios assume significant modifications in the precipitation characteristics over the South-Eastern Europe (SEE), raising a huge interest from the general public and stakeholders. In the recent period, the scientific community has produced many reports showing that the overall precipitation amounts are likely to decrease until the end of the 21st century with variations related to geography, seasons, and parameters. The distribution of the precipitation along the year is key information for water management in hydrologic and agricultural applications, which are very sensitive issues for the SEE countries. This study investigates the observed variability of the seasonality over the SEE (1961-2020), and the expected changes according to IPCC scenarios for the next decades (2021-2050). The analysis exploits the outputs of the Regional Climate Models (RCMs) RegCM3 (ICTP), Aladin (CNRM), and Promes (UCLM), at 25-km spatial resolution and seasonal focus, while ECA&D, and E-OBS datasets were used for featuring the actual climate. Markham (a), and Walsh & Lawler (b) seasonality indices (SI) were computed and employed for the whole area, while the trend analysis was conducted using the nonparametric Mann-Kendall statistics (c), and the Pettitt test (d) and Rodionov Regime Shift Index (e) tests were employed to identify the shifting points. The results pointed out strong differentiations between the different climates in the studied region (e.g. Mediterranean and Carpathian regions), and significant changes in certain spots. Correlated with the variability of the water resources, consumption and availability, the results can be extremely useful for the water management activities. This study is the result of activities developed within the CC-WARE Project (Mitigating Vulnerability of Water Resources under Climate Change), contract no. SEE/D/0143/2.1/X.

  10. Small-Scale Habitat Structure Modulates the Effects of No-Take Marine Reserves for Coral Reef Macroinvertebrates

    PubMed Central

    Dumas, Pascal; Jimenez, Haizea; Peignon, Christophe; Wantiez, Laurent; Adjeroud, Mehdi

    2013-01-01

    No-take marine reserves are one of the oldest and most versatile tools used across the Pacific for the conservation of reef resources, in particular for invertebrates traditionally targeted by local fishers. Assessing their actual efficiency is still a challenge in complex ecosystems such as coral reefs, where reserve effects are likely to be obscured by high levels of environmental variability. The goal of this study was to investigate the potential interference of small-scale habitat structure on the efficiency of reserves. The spatial distribution of widely harvested macroinvertebrates was surveyed in a large set of protected vs. unprotected stations from eleven reefs located in New Caledonia. Abundance, density and individual size data were collected along random, small-scale (20×1 m) transects. Fine habitat typology was derived with a quantitative photographic method using 17 local habitat variables. Marine reserves substantially augmented the local density, size structure and biomass of the target species. Density of Trochus niloticus and Tridacna maxima doubled globally inside the reserve network; average size was greater by 10 to 20% for T. niloticus. We demonstrated that the apparent success of protection could be obscured by marked variations in population structure occurring over short distances, resulting from small-scale heterogeneity in the reef habitat. The efficiency of reserves appeared to be modulated by the availability of suitable habitats at the decimetric scale (“microhabitats”) for the considered sessile/low-mobile macroinvertebrate species. Incorporating microhabitat distribution could significantly enhance the efficiency of habitat surrogacy, a valuable approach in the case of conservation targets focusing on endangered or emblematic macroinvertebrate or relatively sedentary fish species PMID:23554965

  11. Spatial and temporal variability of global surface solar irradiance

    NASA Technical Reports Server (NTRS)

    Bishop, James K. B.; Rossow, William B.

    1991-01-01

    Consideration is given to a fast scheme for computing surface solar irradiance using data from the International Satellite Cloud Climatology Project (ISCCP). Daily mean solar irradiances from the fast scheme reproduce the detailed global results from full radiative transfer model calculations to within 6 and 10 W/sq m over the ocean and land, respectively. Comparison of calculated monthly mean results using 5 m of ISCCP data (July 1983-July 1984) with climatology from the 1970s at six temperature-latitude ocean weather stations shows agreement within published estimates of interannual variability of monthly means at the individual stations. A further test against a 17-day time series at a continental site, where ground and satellite data were spatially and temporally coincident, showed an accuracy of better than 9 W/sq m on a daily basis and less than 4 percent bias in the 17-day mean. Frequently used bulk formulas for solar irradiance are also evaluated in each of these tests.

  12. Spatial variability in hydrologic properties of a volcanic tuff

    SciTech Connect

    Istok, J.D.; Rautman, C.A.; Flint, L.E.; Flint, A.L.

    1994-09-01

    Spatial variability of hydrologic properties was quantified for a nonwelded-to-welded ash flow tuff at Yucca Mountain, Nevada, the potential site of a high-level, nuclear waste repository. Bulk density, porosity, saturated hydraulic conductivity, and sorptivity were measured on core specimens collected from outcrops on a grid that extended vertically through the entire unit thickness and horizontally 1.3 km in the direction of ash transport from the volcanic vent. A strong, geologically determined vertical trend in properties was apparent that correlated with visual trends in degree of welding observed in the outcrop. The trend was accurately described by simple regression models based on stratigraphic elevation. No significant horizontal trends in properties were detected along the length of the transect. The validity of the developed model was tested by comparing model predictions with measured porosity values from additional outcrop sections and boreholes that extended 3,000 m north, 1,500 m northeast, and 6,000 m south of the study area. The model accurately described vertical porosity variations except for locations very close to the source caldera, where the model underpredicted porosity in the upper half of the section. The presence of deterministic geologic trends, such as those demonstrated for an ash flow unit in this study, can simplify the collection of site characterization data and the development of site-scale models.

  13. Emergence of undulatory magnetic flux tubes by small scale reconnections

    NASA Astrophysics Data System (ADS)

    Pariat, E.; Aulanier, G.; Schmieder, B.; Georgoulis, M. K.; Rust, D. M.; Bernasconi, P. N.

    With Flare Genesis Experiment (FGE), a balloon borne observatory launched in Antarctica on January 2000, series of high spatial resolution vector magnetograms, Dopplergrams, and Hα filtergrams have been obtained in an emerging active region (AR 8844). Previous analyses of this data revealed the occurence of many short-lived and small-scale Hα brightenings called 'Ellerman bombs' (EBs) within the AR. We performed an extrapolation of the field above the photosphere using the linear force-free field approximation. The analysis of the magnetic topology reveals a close connexion between the loci of EBs and the existence of ``Bald patches'' regions (BPs are regions where the vector magnetic field is tangential to the photosphere). Among 47 identified EBs, we found that 23 are co-spatial with a BP, while 19 are located at the footpoint of very flat separatrix field lines passing throught a distant BP. We reveal for the first time that some of these EBs/BPs are magneticaly connected by low-lying lines, presenting a 'sea-serpent' shape. This results leads us to conjecture that arch filament systems and active regions coronal loops do not result from the smooth emergence of large scale Ω loops, but rather from the rise of flat undulatory flux tubes which get released from their photospheric anchorage by reconnection at BPs, whose observational signature is Ellerman bombs.

  14. Requirements for future development of small scale rainfall simulators

    NASA Astrophysics Data System (ADS)

    Iserloh, Thomas; Ries, Johannes B.; Seeger, Manuel

    2013-04-01

    Rainfall simulation with small scale simulators is a method used worldwide to assess the generation of overland flow, soil erosion, infiltration and interrelated processes such as soil sealing, crusting, splash and redistribution of solids and solutes. Following the outcomes of the project "Comparability of simulation results of different rainfall simulators as input data for soil erosion modelling (Deutsche Forschungsgemeinschaft - DFG, Project No. Ri 835/6-1)" and the "International Rainfall Simulator Workshop 2011" in Trier, the necessity for further technical improvements of simulators and strategies towards an adaption of designs and methods becomes obvious. Uniform measurements of artificially generated rainfall and comparative measurements on a prepared bare fallow with rainfall simulators used by European research groups showed limitations of the comparability of the results. The following requirements, essential for small portable rainfall simulators, were identified: (I) Low and efficient water consumption for use in areas with water shortage, (II) easy handling and control of test conditions, (III) homogeneous spatial rainfall distribution, (IV) best possible drop spectrum (physically), (V) reproducibility and knowledge of spatial distribution and drop spectrum, (VI) easy and fast training of operators to obtain reproducible experiments and (VII) good mobility and easy installation for use in remote areas and in regions where highly erosive rainfall events are rare or irregular. The presentation discusses possibilities for a common use of identical plot designs, rainfall intensities and nozzles.

  15. Observations of How Magnetofluid Turbulence Dissipates at Small Scales

    NASA Technical Reports Server (NTRS)

    Goldstein, M. L.; Sahraoui, Fouad

    2012-01-01

    The solar wind is a turbulent magneto fluid that can be studied intensively at multiple scales. Investigations using single spacecraft have revealed much about the properties of the solar wind throughout the heliosphere (from 0.3 AU to 100 AU). More recently, data from multiple spacecraft have provided further details of both the statistical properties of the turbulence and its small-scale structure. In particular, high time resolution magnetic field measurements from the four Cluster spacecrafl have led to the conclusion that at spatial scales of order the proton inertial length and smaller, the turbulence becomes strongly anisotropic and the power in fluctuations that are perpendicular to the (local) magnetic field is measured to be much larger than that in fluctuations that are parallel to the magnetic field. As the spatial scales approach the electron inertial length, the power is almost completely dissipated. Various analysis techniques and theoretical ideas have been put forward to account for the properties of those measurements. The talk will describe the current state of observations, theory and simulations.

  16. Arbuscular mycorrhizal fungal communities are phylogenetically clustered at small scales

    PubMed Central

    Horn, Sebastian; Caruso, Tancredi; Verbruggen, Erik; Rillig, Matthias C; Hempel, Stefan

    2014-01-01

    Next-generation sequencing technologies with markers covering the full Glomeromycota phylum were used to uncover phylogenetic community structure of arbuscular mycorrhizal fungi (AMF) associated with Festuca brevipila. The study system was a semi-arid grassland with high plant diversity and a steep environmental gradient in pH, C, N, P and soil water content. The AMF community in roots and rhizosphere soil were analyzed separately and consisted of 74 distinct operational taxonomic units (OTUs) in total. Community-level variance partitioning showed that the role of environmental factors in determining AM species composition was marginal when controlling for spatial autocorrelation at multiple scales. Instead, phylogenetic distance and spatial distance were major correlates of AMF communities: OTUs that were more closely related (and which therefore may have similar traits) were more likely to co-occur. This pattern was insensitive to phylogenetic sampling breadth. Given the minor effects of the environment, we propose that at small scales closely related AMF positively associate through biotic factors such as plant-AMF filtering and interactions within the soil biota. PMID:24824667

  17. Small-scale plasma irregularities in the nightside Venus ionosphere

    NASA Technical Reports Server (NTRS)

    Grebowsky, J. M.; Curtis, S. A.; Brace, L. H.

    1991-01-01

    The individual volt-ampere curves from the Pioneer Venus Orbiter electron temperature probe showed evidence for small-scale density irregularities, or short-period plasma waves, in regions of the nightside ionosphere where the Orbiter electric field detector observed waves in its 100-Hz channel. A survey of the nightside volt-ampere curves has revealed several hundred examples of such irregularities. The I-V structures correspond to plasma density structure with spatial scale sizes in the range of about 100-2000 m, or alternatively they could be viewed as waves having frequencies extending toward 100 Hz. They are often seen as isolated events, with spatial extent along the orbit frequently less than 80 km. The density irregularities or waves occur in or near prominent gradients in the ambient plasma concentrations both at low altitudes where molecular ions are dominant and at higher altitudes in regions of reduced plasma density where O(+) is the major ion. Electric field 100-Hz bursts occur simultaneously, with the majority of the structured I-V curves providing demonstrative evidence that at least some of the E field signals are produced within the ionosphere.

  18. Arbuscular mycorrhizal fungal communities are phylogenetically clustered at small scales.

    PubMed

    Horn, Sebastian; Caruso, Tancredi; Verbruggen, Erik; Rillig, Matthias C; Hempel, Stefan

    2014-11-01

    Next-generation sequencing technologies with markers covering the full Glomeromycota phylum were used to uncover phylogenetic community structure of arbuscular mycorrhizal fungi (AMF) associated with Festuca brevipila. The study system was a semi-arid grassland with high plant diversity and a steep environmental gradient in pH, C, N, P and soil water content. The AMF community in roots and rhizosphere soil were analyzed separately and consisted of 74 distinct operational taxonomic units (OTUs) in total. Community-level variance partitioning showed that the role of environmental factors in determining AM species composition was marginal when controlling for spatial autocorrelation at multiple scales. Instead, phylogenetic distance and spatial distance were major correlates of AMF communities: OTUs that were more closely related (and which therefore may have similar traits) were more likely to co-occur. This pattern was insensitive to phylogenetic sampling breadth. Given the minor effects of the environment, we propose that at small scales closely related AMF positively associate through biotic factors such as plant-AMF filtering and interactions within the soil biota. PMID:24824667

  19. Form drag in rivers due to small-scale natural topographic features: 2. Irregular sequences

    USGS Publications Warehouse

    Kean, J.W.; Smith, J.D.

    2006-01-01

    The size, shape, and spacing of small-scale topographic features found on the boundaries of natural streams, rivers, and floodplains can be quite variable. Consequently, a procedure for determining the form drag on irregular sequences of different-sized topographic features is essential for calculating near-boundary flows and sediment transport. A method for carrying out such calculations is developed in this paper. This method builds on the work of Kean and Smith (2006), which describes the flow field for the simpler case of a regular sequence of identical topographic features. Both approaches model topographic features as two-dimensional elements with Gaussian-shaped cross sections defined in terms of three parameters. Field measurements of bank topography are used to show that (1) the magnitude of these shape parameters can vary greatly between adjacent topographic features and (2) the variability of these shape parameters follows a lognormal distribution. Simulations using an irregular set of topographic roughness elements show that the drag on an individual element is primarily controlled by the size and shape of the feature immediately upstream and that the spatial average of the boundary shear stress over a large set of randomly ordered elements is relatively insensitive to the sequence of the elements. In addition, a method to transform the topography of irregular surfaces into an equivalently rough surface of regularly spaced, identical topographic elements also is given. The methods described in this paper can be used to improve predictions of flow resistance in rivers as well as quantify bank roughness.

  20. ANALYSIS OF COVARIANCE WITH SPATIALLY CORRELATED SECONDARY VARIABLES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Data sets which contain measurements on a spatially referenced response and covariate are analyzed using either co-kriging or spatial analysis of covariance. While co-kriging accounts for the correlation structure of the covariate, it is purely a predictive tool. Alternatively, spatial analysis of c...

  1. Practical small-scale explosive seam welding

    NASA Technical Reports Server (NTRS)

    Bement, L. J.

    1983-01-01

    Joining principles and variables, types of joints, capabilities, and current and potential applications are described for an explosive seam welding process developed at NASA Langley Research Center. Variable small quantities of RDX explosive in a ribbon configuration are used to create narrow (less than 0.5 inch), long length, uniform, hermetrically sealed joints that exhibit parent metal properties in a wide variety of metals, alloys, and combinations. The first major all application of the process is the repair of four nuclear reactors in Canada. Potential applications include pipelines, sealing of vessels, and assembly of large space structures.

  2. Reconnection rates, small scale structures and simulations

    NASA Technical Reports Server (NTRS)

    Matthaeus, W. H.

    1983-01-01

    The study of reconnection in the context of one fluid, two dimensional magnetohydrodynamics (MHD), with spatially uniform constant density, viscosity and resistivity is though to retain most of the physics important in reconnection. Much of the existing reconnection literature makes use of this approach. This discussion focuses on attempts to determine the properties of reconnection solutions to MHD as precisely as possible without regard to the intrinsic limitations of the model.

  3. Spatial variability in degassing at Erebus volcano, Antarctica

    NASA Astrophysics Data System (ADS)

    Ilanko, Tehnuka; Oppenheimer, Clive; Kyle, Philip; Burgisser, Alain

    2015-04-01

    Erebus volcano on Ross Island, Antarctica, hosts an active phonolitic lava lake, along with a number of persistently degassing vents in its summit crater. Flank degassing also occurs through ice caves and towers. The longevity of the lake, and its stable convection, have been the subject of numerous studies, including Fourier transform infrared (FTIR) spectroscopy of the lava lake. Two distinct gas compositions were previously identified in the main lava lake plume (Oppenheimer et al., 2009; 2011): a persistent 'conduit' gas with a more oxidised signature, ascribed to degassing through a permeable magma conduit; and a H2O- and SO2- enriched 'lake' composition that increases and decreases cyclically due to shallow degassing of incoming magma batches. During the past decade of annual field seasons on Erebus, gas compositions have been measured through FTIR spectroscopy at multiple sites around Erebus volcano, including flank degassing through an ice cave (Warren Cave). We present measurements from four such vents, and compare their compositions to those emitted from the main lava lake. Summit degassing involves variable proportions of H2O, CO2, CO, SO2, HF, HCl, OCS. Cyclicity is evident in some summit vents, but with signatures indicative of shallower magmatic degassing than that of the lava lake. By contrast, flank degassing at Warren Cave is dominated by H2O, CO2, and CH4. The spatial variability in gas compositions within the summit crater suggests an alternative origin for 'conduit' and 'lake' degassing to previous models that assume permeability in the main conduit. Rather, the two compositions observed in main lake degassing may be a result of decoupled 'conduit' gas and pulses of magma rising through discrete fractures before combining in the lake floor or the main plume. Smaller vents around the crater thus emit isolated 'lake' or 'conduit' compositions while their combined signature is observed in the lava lake. We suggest that this separation between gas

  4. SCION: CubeSat Mission Concept to Observe Midlatitude Small-Scale Irregularities and Scintillation

    NASA Astrophysics Data System (ADS)

    Heine, T.; Moldwin, M.

    2014-12-01

    The SCintillation and Ionospheric Occultation NanoSats (SCION) mission concept is to deploy two low-cost CubeSat spacecraft that maintain a separation distance <1 km to measure scintillation and associated small-scale density irregularities in the midlatitude ionosphere. Each spacecraft is equipped with a dual frequency GPS receiver to measure total electron content (TEC) and the S4 scintillation index along raypaths from the receiver to the GPS constellation. Scintillation causing small-scale density irregularities are increasingly observed in the vicinity of large TEC gradients associated with storm enhanced density (SED) regions. Detection of irregularities of the scale that cause GPS and VHF scintillation has previously relied on assumptions about their structural stability and drift speed. Space-based, multipoint observations would provide broad, regional coverage and disambiguation of temporal and spatial density fluctuations in order to detect small-scale irregularities without these assumptions.

  5. Spatial variability of atmospheric semivolatile organic compounds in Chile

    NASA Astrophysics Data System (ADS)

    Shunthirasingham, Chubashini; Barra, Ricardo; Mendoza, Gonzalo; Montory, Monica; Oyiliagu, Catherine E.; Lei, Ying Duan; Wania, Frank

    2011-01-01

    In an effort to characterize the spatial variability of pesticides, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) in the Chilean atmosphere, XAD-based passive air samplers (PAS) were deployed for 12 months (2006-2007) along three elevational gradients in Northern, Central and Southern Chile, for a total of 20 sampling sites, ranging in elevation from 10 to 4400 m and ranging over 26 degrees of latitude. Hexachlorobenzene (HCB) had largely uniform air concentrations with latitude and altitude, and is therefore used to derive sampler specific sampling rates, that account for differences in uptake kinetics due to environmental factors such as altitude and temperature. Levels of pesticides in the atmosphere of Chile are very low and only α- and γ-hexachlorocyclohexane, α-endosulfan and chlorothalonil were present in all of the samples. The concentrations of these four pesticides in air decreased from North to South, with much steeper gradients for chlorothalonil and endosulfan. Chlorothalonil levels were greatly elevated in air samplers deployed in urban locations. Endosulfan concentrations in air tend to increase with elevation. Since endosulfan is particularly susceptible to mountain cold-trapping, such gradients may reflect the re-volatilization of endosulfan that had been preferentially deposited at higher altitudes. Alternatively, increasing endosulfan concentrations with elevation could be the result of transport to higher altitude sites from the other side of Andes. Airshed analysis indeed indicates that air masses originating outside of Chile have a higher influence on the higher elevation sites, especially along the Northern transect. Concentrations of four-ring PAHs ranged from 0.3 to 1300 pg m -3, with higher levels in air samplers deployed in urban areas and close to roads. PCB concentrations were low (0.7-27 pg m -3), with slightly higher levels of volatile congeners in two urban sampling sites in Concepcion and Arica

  6. Spatial and seasonal variability of carbonaceous aerosol across Italy

    NASA Astrophysics Data System (ADS)

    Sandrini, Silvia; Fuzzi, Sandro; Piazzalunga, Andrea; Prati, Paolo; Bonasoni, Paolo; Cavalli, Fabrizia; Bove, Maria Chiara; Calvello, Mariarosaria; Cappelletti, David; Colombi, Cristina; Contini, Daniele; de Gennaro, Gianluigi; Di Gilio, Alessia; Fermo, Paola; Ferrero, Luca; Gianelle, Vorne; Giugliano, Michele; Ielpo, Pierina; Lonati, Giovanni; Marinoni, Angela; Massabò, Dario; Molteni, Ugo; Moroni, Beatrice; Pavese, Giulia; Perrino, Cinzia; Perrone, Maria Grazia; Perrone, Maria Rita; Putaud, Jean-Philippe; Sargolini, Tiziana; Vecchi, Roberta; Gilardoni, Stefania

    2014-12-01

    This paper analyses elemental (EC), organic (OC) and total carbon (TC) concentration in PM2.5 and PM10 samples collected over the last few years within several national and European projects at 37 remote, rural, urban, and traffic sites across the Italian peninsula. The purpose of the study is to obtain a picture of the spatial and seasonal variability of these aerosol species in Italy, and an insight into sources, processes and effects of meteorological conditions. OC and EC showed winter maxima and summer minima at urban and rural locations and an opposite behaviour at remote high altitude sites, where they increase during the warm period due to the rising of the Planetary Boundary Layer (PBL). The seasonal averages of OC are higher during winter compared to summer at the rural sites in the Po Valley (from 1.4 to 3.5 times), opposite to what usually occurs at rural locations, where OC increases during the warm period. This denotes the marked influence of urban areas on the surrounding rural environment in this densely populated region. The different types of sites exhibit marked differences in the average concentrations of carbonaceous aerosol and OC/EC ratio. This ratio is less sensitive to atmospheric processing than OC and EC concentrations, and hence more representative of different source types. Remote locations are characterised by the lowest levels of OC and especially EC, with OC/EC ratios ranging from 13 to 20, while the maximum OC and EC concentrations are observed at road-traffic influenced urban sites, where the OC/EC ratio ranges between 1 and 3. The highest urban impacts of OC and EC relative to remote and rural background sites occur in the Po Valley, especially in the city of Milan, which has the highest concentrations of PM and TC and low values of the OC/EC ratio.

  7. Small-Scale Farming: A Portrait from Polk County, Oregon.

    ERIC Educational Resources Information Center

    Young, John A.; Caday, Peter

    A study of small-scale farmers in Polk County, Oregon, examined characteristics of, and variations among, small-scale farmers and developed some guidelines for assistance programs targeted for such a group. During the months of May, June, and July of 1978 an average of 4 days a week was spent locating and interviewing 44 small farm operators in…

  8. Small-scale swirl events in the quiet Sun chromosphere

    NASA Astrophysics Data System (ADS)

    Wedemeyer-Böhm, S.; Rouppe van der Voort, L.

    2009-11-01

    Context: Recent progress in instrumentation enables solar observations with high resolution simultaneously in the spatial, temporal, and spectral domains. Aims: We use such high-resolution observations to study small-scale structures and dynamics in the chromosphere of the quiet Sun. Methods: We analyse time series of spectral scans through the Ca ii 854.2 nm spectral line obtained with the CRISP instrument at the Swedish 1-m Solar Telescope. The targets are quiet Sun regions inside coronal holes close to disc-centre. Results: The line core maps exhibit relatively few fibrils compared to what is normally observed in quiet Sun regions outside coronal holes. The time series show a chaotic and dynamic scene that includes spatially confined “swirl” events. These events feature dark and bright rotating patches, which can consist of arcs, spiral arms, rings or ring fragments. The width of the fragments typically appears to be of the order of only 0.2 arcsec, which is close to the effective spatial resolution. They exhibit Doppler shifts of -2 to -4 km s-1 but sometimes up to -7 km s-1, indicating fast upflows. The diameter of a swirl is usually of the order of 2´´. At the location of these swirls, the line wing and wide-band maps show close groups of photospheric bright points that move with respect to each other. Conclusions: A likely explanation is that the relative motion of the bright points twists the associated magnetic field in the chromosphere above. Plasma or propagating waves may then spiral upwards guided by the magnetic flux structure, thereby producing the observed intensity signature of Doppler-shifted ring fragments. The movie is only available in electronic form at http://www.aanda.org Marie Curie Intra-European Fellow of the European Commission.

  9. Risk of Resource Failure and Toolkit Variation in Small-Scale Farmers and Herders

    PubMed Central

    Collard, Mark; Ruttle, April; Buchanan, Briggs; O’Brien, Michael J.

    2012-01-01

    Recent work suggests that global variation in toolkit structure among hunter-gatherers is driven by risk of resource failure such that as risk of resource failure increases, toolkits become more diverse and complex. Here we report a study in which we investigated whether the toolkits of small-scale farmers and herders are influenced by risk of resource failure in the same way. In the study, we applied simple linear and multiple regression analysis to data from 45 small-scale food-producing groups to test the risk hypothesis. Our results were not consistent with the hypothesis; none of the risk variables we examined had a significant impact on toolkit diversity or on toolkit complexity. It appears, therefore, that the drivers of toolkit structure differ between hunter-gatherers and small-scale food-producers. PMID:22844421

  10. Spatial variability of soil parameters - subsoils as heterogenic environments

    NASA Astrophysics Data System (ADS)

    Heinze, Stefanie; John, Stephan; Kirfel, Kristina; Mikutta, Robert; Niebuhr, Jana; Preusser, Sebastian; Marschner, Bernd

    2014-05-01

    Subsoils are known to store a high amount of organic carbon (40-60% of the total C-pool). 14C-dating detected that in subsoils organic matter (OM) age increased with increasing depth and reaches several 1000 years. The high age of subsoil OM might be caused by a complex structure, by limited access of OM for microbial decomposition or a limited input of fresh organic material. The latter, mostly reaches the subsoil through special pathways, like root channels, bioturbation processes or preferential flow pathways where dissolved organic carbon will be transported. The spatially concentrated input of OM supposed that the heterogeneity of physical, chemical, and biological soil parameters is higher in subsoils than in top soils. Within the DFG-FOR 1806 we investigated the heterogeneity of soil parameters in soil profiles (top and subsoil) of a podzolic Cambisol in a 95 years old beech forest in Lower Saxony, Germany. Three transects were established with a vertical and horizontal dimension of 2.00m and 3.15m, respectively. 64 soil samples were taken out of a grid in 10, 35, 60, 85, 110, 135, 160 and 185m depth with increasing horizontal distance to a main tree. To analyze the variability and relationship of soil properties in the soil profiles, analysis of soil physical (e.g. texture), chemical (e.g. organic C, dissolved organic C, total N, pH), and biological (e.g. enzyme activities, microbial biomass C) parameters were conducted within the research group. The results showed a very strong decline of organic C from 1.15% (10cm) to 0.12% (60cm). The differences of SOC were not pronounced with increasing distance to the main tree. Also total nitrogen decreased between 10 and 60cm strongly from 0.05 to 0.005%. The pH showed a slight increase between 10 and 35cm from 3.51 up to 4.27. For microbial biomass measures the same stratification was detected but the variance within biological parameters were higher in the subsoil than in the topsoil. Enzyme activities showed a

  11. Spatial variabilities in Sky Island subalpine hydro/micrometeorology

    NASA Astrophysics Data System (ADS)

    Brown-Mitic, C. M.; Harlow, C.; Shuttleworth, J.; Bales, R.

    2003-04-01

    differences in net radiation is reflected in the surface temperature potential for heat transfer. During the winter, although there is similarity in net radiation, air temperature and relative humidity, these two sites exhibit a significant difference in the potential for heat transfer. These variabilities coupled with the added complexities in flow regimes induced my non-flat mountainous terrain, are significant considerations when attempting to scale single tower observations to the canopy or when single tower observations are used to represent conditions over a small watershed for such purposes as spatial snow melt modeling. The observations and results from this network will be presented in relationship to observations from the eddy correlation flux tower.

  12. The active liquid Earth - importance of temporal and spatial variability

    NASA Astrophysics Data System (ADS)

    Arheimer, Berit

    2016-04-01

    The Planet Earth is indeed liquid and active - 71 percent of its surface is water-covered and this water never rests. Thanks to the water cycle, our planet's water supply is constantly moving from one place to another and from one form to another. Only 2.5% of the water is freshwater and it exists in the air as water vapor; it hits the ground as rain and snow; it flows on the surface from higher to lower altitudes in rivers, lakes, and glaciers; and it flows in the ground in soil, aquifers, and in all living organisms until it reaches the sea. On its way over the Earth's crust, some returns quickly to vapor again, while some is trapped and exposed to many "fill and spill" situations for a long journey. The variability in the water balance is crucial for hydrological understanding and modelling. The water cycle may appear simple, but magnitudes and rates in fluxes are very different from one place to another, resulting from variable drivers such as solar energy, precipitation and gravity in co-evolution with geology, soil, vegetation and fauna. The historical evolution, the temporal fluxes and diversity in space continue to fascinate hydrological scientists. Specific physical processes may be well known, but their boundary conditions, interactions and rate often remain unknown at a specific site and are difficult to monitor in nature. This results in mysterious features where trends in drivers do not match runoff, like the Sahelian Paradox or discharge to the Arctic Ocean. Humans have always interfered with the water cycle and engineering is fundamental for water regulation and re-allocation. Some 80% of the river flow from the northern part of the Earth is affected by fragmentation of the river channels by dams. In water management, there is always a tradeoff between upstream and downstream activities, not only regarding total water quantities but also for temporal patterns and water quality aspects. Sharing a water resource can generate conflicts but geopolitical

  13. Simulating maize yield and biomass with spatial variability of soil field capacity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Spatial variability in field soil water and other properties is a challenge for system modelers who use only representative values for model inputs, rather than their distributions. In this study, we compared simulation results from a calibrated model with spatial variability of soil field capacity ...

  14. SOIL-LANDSCAPE SPATIAL VARIABILITY IMPACT ON NON-IRRIGATED COTTON YIELD

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Topographical land features greatly influence spatial variability of soils and in turn affects cotton (Gossypium hirsutum L.) yield, especially under dryland conditions. Objectives of this study are to 1) characterize spatial variability of soil physical properties in a complex, non-irrigated lands...

  15. Spatial variability of soil properties using nested variograms at multiple scales

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Determining the spatial structure of data is important in understanding within-field variability for site-specific crop management. The structure of variability determines the required spatial intensity of data collection and can be used for directing the delineation of management zones. Especially ...

  16. Emergence of undulatory magnetic flux tubes by small scale reconnections

    NASA Astrophysics Data System (ADS)

    Pariat, E.; Aulanier, G.; Schmieder, B.; Georgoulis, M. K.; Rust, D. M.; Bernasconi, P. N.

    2006-01-01

    With Flare Genesis Experiment (FGE), a balloon borne observatory launched in Antarctica on January 2000, series of high spatial resolution vector magnetograms, Dopplergrams, and Hα filtergrams have been obtained in an emerging active region (AR 8844). Previous analyses of this data revealed the occurence of many short-lived and small-scale H α brightenings called 'Ellerman bombs' (EBs) within the AR. We performed an extrapolation of the field above the photosphere using the linear force-free field approximation. The analysis of the magnetic topology reveals a close connexion between the loci of EBs and the existence of "Bald patches" (BP) regions (BPs are regions where the vector magnetic field is tangential to the photosphere). Some of these EBs/BPs are magnetically connected by low-lying field lines, presenting a serpentine shape. This results leads us to conjecture that arch filament systems and active regions coronal loops do not result from the smooth emergence of large scale Ω-loops, but rather from the rise of flat undulatory flux tubes which get released from their photospheric anchorage by reconnection at BPs, which observational signature is Ellerman bombs.

  17. Small-scale turbulence detected in Mercury's magnetic field

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2011-11-01

    With its closest approach a mere 46 million kilometers from the Sun, the blast of the solar wind was supposed to wash away any chance that Mercury could hold on to a magnetic field—an idea rejected by the observations of the Mariner 10 spacecraft in 1974. Though Mercury was shown to harbor a weak magnetic field (one-hundredth the strength of Earth's), its structure, behavior, and interactions with the solar wind remained heavily debated, yet untested, until the 14 January 2008 approach of NASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) orbiter. Using a continuous scalogram analysis—a novel statistical technique in space research—Uritsky et al. analyzed the high-resolution magnetic field strength observations taken by MESSENGER as it flew within a few hundred kilometers of the planet's surface. The authors found turbulence in Mercury's magnetosphere, which they attributed to small-scale interactions between the solar wind plasma and the magnetic field. At large spatial and temporal scales the solar wind can be thought of as a fluid with some magnetic properties—a domain well explained by the theories of magnetohydrodynamics.

  18. Spatial Variability and Correlation of Selected Soil Properties in the AP Horizon of the CRP Grassland

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Knowledge of the spatial variability of soil properties in agricultural fields is important for implementing various precision agricultural management practices. This paper examines spatial variation of selected soil physical and chemical properties and explores their spatial correlation in the A ho...

  19. Detecting small scale CO2 emission structures using OCO-2

    NASA Astrophysics Data System (ADS)

    Schwandner, Florian M.; Eldering, Annmarie; Verhulst, Kristal R.; Miller, Charles E.; Nguyen, Hai M.; Oda, Tomohiro; O'Dell, Christopher; Rao, Preeti; Kahn, Brian; Crisp, David; Gunson, Michael R.; Sanchez, Robert M.; Ashok, Manasa; Pieri, David; Linick, Justin P.; Yuen, Karen

    2016-04-01

    Localized carbon dioxide (CO2) emission structures cover spatial domains of less than 50 km diameter and include cities and transportation networks, as well as fossil fuel production, upgrading and distribution infra-structure. Anthropogenic sources increasingly upset the natural balance between natural carbon sources and sinks. Mitigation of resulting climate change impacts requires management of emissions, and emissions management requires monitoring, reporting and verification. Space-borne measurements provide a unique opportunity to detect, quantify, and analyze small scale and point source emissions on a global scale. NASA's first satellite dedicated to atmospheric CO2 observation, the July 2014 launched Orbiting Carbon Observatory (OCO-2), now leads the afternoon constellation of satellites (A-Train). Its continuous swath of 2 to 10 km in width and eight footprints across can slice through coincident emission plumes and may provide momentary cross sections. First OCO-2 results demonstrate that we can detect localized source signals in the form of urban total column averaged CO2 enhancements of ~2 ppm against suburban and rural backgrounds. OCO-2's multi-sounding swath observing geometry reveals intra-urban spatial structures reflected in XCO2 data, previously unobserved from space. The transition from single-shot GOSAT soundings detecting urban/rural differences (Kort et al., 2012) to hundreds of soundings per OCO-2 swath opens up the path to future capabilities enabling urban tomography of greenhouse gases. For singular point sources like coal fired power plants, we have developed proxy detections of plumes using bands of imaging spectrometers with sensitivity to SO2 in the thermal infrared (ASTER). This approach provides a means to automate plume detection with subsequent matching and mining of OCO-2 data for enhanced detection efficiency and validation. © California Institute of Technology

  20. Small-scale structures in common-volume meteor wind measurements

    NASA Astrophysics Data System (ADS)

    Fraser, G. J.; Marsh, S. H.; Baggaley, W. J.; Bennett, R. G. T.; Lawrence, B. N.; McDonald, A. J.; Plank, G. E.

    2006-02-01

    Observational differences occur when different techniques are used for measuring mesospheric winds because the different instruments observe different physical quantities to infer the wind velocity, and have differing time and space resolution. The AMOR meteor wind radar near Christchurch, New Zealand [Marsh et al., 2000. Journal of Atmospheric and Solar-Terrestrial Physics 62,1129 1133.] has good resolution in time (˜0.1 s) and height (˜1 km) and a narrow beam centred in the geographic N S meridian. The meteor echoes randomly sample the atmosphere in a region extending over several hundred kilometres to the South of the radar. The volume of data obtained from the one instrument has made it possible to use correlations between measurements made from individual meteor trails to identify the contribution of atmospheric variability to the observational differences. Measurements of the meridional wind component made from May July 1997 inclusive show that a large part (20 30 m/s r.m.s.) of the atmospheric variation is due to inhomogeneities with small scales, of the order of 10 km and 1 h. There is also a component which has a random time phase over the observation interval but a spatial scale which is coherent over several hundred kilometres, consistent with the behaviour of gravity waves.

  1. Capital cost of small-scale tidal power plants

    SciTech Connect

    Fay, J.A.; Smachio, M.A.

    1983-11-01

    A generic methodology is devised for estimating the capital costs of small-scale tidal power plants (1-100 MW rated power). In addition to the general dimensions determining the size of the tidal pond resource (surface area and tidal range) two site-specific dimensions (depth and length of closure structure) are required for this estimate. Dimensionless parameters and variables describing the power plant performance are used in the cost analysis to specify the relative sizes of the power plant components (turbine-generator, power house, sluice gates, cofferdam, and barrage). The generic cost estimates are compared with those used in several site-specific studies. Unit total capital cost (cost per unit of average power produced) is calculated as a function of the size of the tidal pond resource, the latter being measured in terms of the ideal tidal pond power. A range of closure depths and lengths was used in these generic cost estimates. The minimum unit capital cost is shown to depend upon the size of the tidal pond as well as the site-specific dimensions. An optimum turbogenerator size can be determined to minimize the capital cost.

  2. A Small-Scale Safety Test for Initiation Components

    SciTech Connect

    Cutting, J; Chow, C; Chau, H; Hodgin, R; Lee, R

    2002-04-22

    We have developed a small-scale safety test for initiation train components. A low-cost test was needed to assess the response of initiation components to an abnormal shock environment and to detect changes in the sensitivity of initiation components as they age. The test uses a disk of Detasheet to transmit a shock through a PMMA barrier into a the test article. A schematic drawing of the fixture is shown. The 10-cm-diameter disk of 3-mm-thick Detasheet, initiated at its center by a RISI, RP detonator, produces a shock wave that is attenuated by a variable-thickness PMMA spacer (gap). Layers of metal and plastic above the test article and the material surrounding the test article may be chosen to mock up the environment of the test article at its location in a warhead. A metal plate at the bottom serves as a witness plate to record whether or not the test article detonated. For articles containing a small amount of explosive, it can be difficult to determine whether or not a detonation has occurred. In such cases, one can use a pressure transducer or laser velocimeter to detect the shock wave from the detonation of the article. The assembly is contained in a 10-cm-ID section of PVC pipe and fired in a containment vessel rated at 100 g. Test results are given for a hemispherical, exploding-bridgewire (EBW) detonator.

  3. Temporal and Spatial Variability in Landslide Susceptibility Analyses

    NASA Astrophysics Data System (ADS)

    Trizzino, Rosamaria; Pagliarulo, Rossella

    2014-05-01

    The geomorphic processes in landscape evolution are commonly assumed deterministic, although their high variability in rates and time. As the stability analyses of slopes are concerned, the classical methods consider threshold values of the different elements (slope angle, friction angle, climatic conditions, hydrogeological conditions, seismicity) that condition the safety factors, but often widespread landscape instabilities occur when the threshold values are not exceeded. To analyze these phenomena we studied a model for defining an "average" pattern of landscape evolution starting from the single deterministic process. Many previous studies demonstrated the driving role of weathering and erosion processes in landslide evolution. Among these, the "instability principle of geomorphic equilibrium" (Scheidegger, 1983) stated the relevancy of exogenic processes (weathering, erosion, etc.) particularly in those places where preexisting micro topographic irregularities or lithological variations are recognizable. The present paper gives an example of the unstable growth of small perturbations from the initial conditions up to the landslide initiation, even if there were no measurable variations in external controls. In this analysis the geo- materials are considered as a weathering system mathematically depicted as an n-components nonlinear dynamical system. A hierarchical multiscale model of instability is applied. The model treats four spatial scales: 1) local regolith scale (weathering processes, in situ breakdown of geo-materials), 2) hill slope scale (allocation of weathered products: soil removal in solid form, via erosion and mass wasting, or in dissolved form via surface water flow), 3) landscape units (relationships between weathering and denudation), 4) broadest landscape scale (topographic and isostatic response to weathering-limited denudation, unloading or depositional loading). The landslide susceptibility analysis for the present study is located in

  4. Spatial variability of the trends in climatic variables across China during 1961-2010

    NASA Astrophysics Data System (ADS)

    Yang, Hanbo; Yang, Dawen; Hu, Qingfang; Lv, Huafang

    2015-05-01

    Distribution of meteorological stations is not uniform in many regions of the world, especially in developing countries like China. To eliminate the effect of uneven stations, this study produced a data set of areal average precipitation, air temperature, solar radiation, and wind speed from 736 meteorological station observations during 1961-2010 using an inverse-distance weighted technique. Based on the data set, this study detected the trends in climatic variables. Precipitation has a slight but no significant ( p = 0.78) trend for the whole of China and has a significant increase trend in northwest China. Surface air temperature has a significant ( p < 0.001) accelerating warming trend of 0.032 °C/a for the whole of China, and spatially larger in northern China than that in southern China. Solar radiation has a significant ( p < 0.001) dimming trend of -0.14 W/(m2 · a) for the whole of China, and the largest dimming trend appears in eastern China, the possible cause for which is a high-aerosol concentration. Surface wind speed has a significant ( p < 0.001) stilling trend of -0.012 m/(s·a) for the whole of China, the causes for which were speculated the changes in atmospheric circulation and surface roughness, as well as increases in aerosol concentration and the decrease in the south-north temperature gradient in China. In addition, three large-scale instrument replacements increase uncertainties of the trend analysis.

  5. Spatial and temporal variability of grass cover in two olive grove catchments on contrasting soil types

    NASA Astrophysics Data System (ADS)

    Aguilera, Laura; Taguas, Encarnación V.; Gimeno, Enrique; Gómez, José A.

    2013-04-01

    Mediterranean climate conditions -characterized by the concentration of the precipitation in the seasons of autumn and spring, the low temperatures in winter and extremely warm and dry summers- determine that ground cover by adventitious (or cover crop) vegetation shows significant seasonal and annual variability. In addition, its spatial variability associates also, partially, to water availability among the landscape. This is especially relevant in olive orchards, an agricultural system under high erosion risk in the region where the establishment of herbaceous cover has proved to improve soil protection reducing erosion risk, as well as the improvement of soil properties (Gómez et al., 2009). All these benefits are based on small scale studies where full ground cover by the cover crop is relatively easy to obtain. However, few information is available about the actual ground cover achieved at farm scale, although preliminary observations suggests that this might be extremely variable (Gómez and Giráldez, 2009). This study presents the preliminary results evaluating the spatial and temporal evolution of ground cover by adventitious vegetation (the preferred option by farmers to achieve a cover crop) in two commercial olive farms during 2 hydrological years (2011-2012). The study was conducted in two farms located in the province of Cordoba, Southern Spain. Both were olive orchards grown under deficit irrigation systems and present a gauge station where rainfall, runoff and sediment loads have been measured from the year 2005. The soil management in "La Conchuela" farm was based in the use of herbicide in the line of olive trees to keep the bare soil all year round, and the application of selective herbicide in the lane between the olive trees to promote the grown of graminaceae grasses . In addition, the grass is mechanically killed in June. In the another farm, "Arroyo Blanco", the grass spontaneous cover is allowed until mid-spring in which is also

  6. A Small-Scale Low-Cost Gas Chromatograph

    ERIC Educational Resources Information Center

    Gros, Natasa; Vrtacnik, Margareta

    2005-01-01

    The design and application of a small-scale portable gas chromatograph for learning of the basic concepts of chromatography is described. The apparatus consists of two basic separable units, which includes a chromatographic unit and an electronic unit.

  7. Small scale thematic mapping - A case for radar imagery

    NASA Technical Reports Server (NTRS)

    Henderson, F. M.

    1974-01-01

    Small scale thematic maps (1:250,000 and smaller) of physical and cultural phenomena manifested on the landscape are a major concern to scientists and investigators in diverse disciplines. A strip of K-band radar imagery consisting of a traverse from eastern Minnesota to northern Utah was employed to evaluate the potential of radar imagery for small scale land use mapping. In the course of this investigation, it was discovered that certain borders derived from radar imagery were compatible with borders found on the nonland use thematic maps used for comparison. Specifically, numerous borders and regions of small scale maps of landforms, soils, vegetation, and geology are found to be similar to the radar land use regions. Although far from conclusive it appears that radar imagery can be employed in the small scale mapping of landforms and possibly for mapping physiognomic or economic vegetation.

  8. Can APEX Represent In-Field Spatial Variability and Simulate Its Effects On Crop Yields?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Precision agriculture, from variable rate nitrogen application to precision irrigation, promises improved management of resources by considering the spatial variability of topography and soil properties. Hydrologic models need to simulate the effects of this variability if they are to inform about t...

  9. [Spatial Variability and Distribution Pattern of Soil Organic Matter in a Mollisol Watershed of China].

    PubMed

    Gao, Feng-jie; Ma, Quan-lai; Han, Wen-wen; Shan, Pei-ming; Zhou, Jun; Zhang, Shao-liang; Zhang, Zhi-min; Wang, Hong-yan

    2016-05-15

    Spatial variability of soil organic matter and its distribution pattern are the hot issues of soil scientific research. Selecting Haigouhe watershed as the study area, this paper mainly focused on the spatial variability, distribution pattern and its impact factors of SOM in the surface soil by classical statistics, Geo-statistics and "3S" technology. The results showed that: compared with the other black soil areas, the SOM content in Haigouhe watershed was a little lower, there was a spatial autocorrelation, and a moderate variability. Random factors, such as human activities, cultivation measures and so on, had little impact on the spatial variation, while the structural factors had a dominant function, and there was a remarkable spatial anisotropy of SOM. The SOM content reduced gradually from east to west with the familiar changes of height, so the co-kriging interpolation, selecting elevation as the co-variate, was employed to improve the accuracy. The spatial variability of SOM and its distribution pattern in Haigouhe watershed were greatly affected by topography and land use but weakly influenced by traffic, villages and other social factors. The surrounding environment of the samples would increase the uncertainty of spatial variability and interpolation of SOM and it cannot be ignored in future studies. In summary, it was a significant scientific research to analyze the spatial variability, distribution pattern of SOM and its main impact factors in a mollisol hilly watershed of China. PMID:27506048

  10. AUTOMATED COTTON SAMPLER FOR DETERMINATION OF FIBER QUALITY SPATIAL VARIABILITY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Development of accurate prescription maps for site-specific management of crops requires knowledge of the spatially registered crop profitability. In cotton (Gossypium L. sps.), the quality of the crop alters the price paid for the lint, and hence is an important determinant of the net profit. Cotto...