ALBERT

Beschreibung: Abstract Experimental study of the effects of projected climate change on plant phenology allows us to isolate effects of warming on life history events such as leaf out. We simulated a 2°C temperature increase and 20% precipitation increase in a recently harvested temperate deciduous forest community in central Pennsylvania, USA, and observed the leaf out phenology of all species in 2009 and 2010. Over 130 plant species were monitored weekly in study plots, but due to high variability in species composition among plots, species were grouped into five functional groups: short forbs, tall forbs, shrubs, small trees, and large trees. Tall forbs and large trees, which usually emerge in the late spring, advanced leaf out 14‐18 days in response to warming. Short forbs, shrubs, and small trees emerge early in spring and did not alter their phenology in response to warming or increased precipitation treatments. Earlier leaf out of tall forbs and large trees coincided with almost three weeks of increased community‐level leaf area index (LAI), indicating greater competition and a condensed spring green‐up period. While phenology of large trees and tall forbs appears to be strongly influenced by temperature‐based growth cues, our results suggest that photoperiod and chilling cues more strongly influence the leaf out of other functional groups. Reduced freeze events and warmer temperatures from predicted climate change will interact with non‐temperature growth cues to have cascading consequences throughout the ecosystem.

Beschreibung: To monitor compliance with the Comprehensive Nuclear-Test ban Treaty (CTBT), a dedicated International Monitoring System (IMS) is being deployed. Recent global scale observations recorded by this network confirm that its detection capability is highly variable in space and time. Previous studies estimated the radiated source energy from remote observations using empirical yield-scaling relations which account for the along-path stratospheric winds. Although the empirical wind correction reduces the variance in the explosive energy versus pressure relationship, strong variability remains in the yield estimate. Today, numerical modeling techniques provide a basis to better understand the role of different factors describing the source and the atmosphere that influence propagation predictions. In this study, the effects of the source frequency and the stratospheric wind speed are simulated. In order to characterize fine-scale atmospheric structures which are excluded from the current atmospheric specifications, model predictions are further enhanced by the addition of perturbation terms. A theoretical attenuation relation is thus developed from massive numerical simulations using the Parabolic Equation method. Compared with previous studies, our approach provides a more realistic physical description of long-range infrasound propagation. We obtain a new relation combining a near-field and a far-field term, which account for the effects of both geometrical spreading and absorption. In the context of the future verification of the CTBT, the derived attenuation relation quantifies the spatial and temporal variability of the IMS infrasound network performance in higher resolution, and will be helpful for the design and prioritizing maintenance of any arbitrary infrasound monitoring network.

Beschreibung: A major difficulty when inverting the source term of an atmospheric tracer dispersion problem is the estimation of the prior errors: those of the atmospheric transport model, those ascribed to the representativity of the measurements, those that are instrumental, and those attached to the prior knowledge on the variables one seeks to retrieve. In the case of an accidental release of pollutant, the reconstructed source is sensitive to these assumptions. This sensitivity makes the quality of the retrieval dependent on the methods used to model and estimate the prior errors of the inverse modeling scheme. We propose to use an estimation method for the errors' amplitude based on the maximum likelihood principle. Under semi-Gaussian assumptions, it takes into account, without approximation, the positivity assumption on the source. We apply the method to the estimation of the Fukushima Daiichi source term using activity concentrations in the air. The results are compared to an L-curve estimation technique and to Desroziers's scheme. The total reconstructed activities significantly depend on the chosen method. Because of the poor observability of the Fukushima Daiichi emissions, these methods provide lower bounds for cesium-137 and iodine-131 reconstructed activities. These lower bound estimates, 1.2 × 1016 Bq for cesium-137, with an estimated standard deviation range of 15%–20%, and 1.9 − 3.8 × 1017 Bq for iodine-131, with an estimated standard deviation range of 5%–10%, are of the same order of magnitude as those provided by the Japanese Nuclear and Industrial Safety Agency and about 5 to 10 times less than the Chernobyl atmospheric releases.

Beschreibung: This study is our first step toward the generation of 6 hourly 3-D CO2 fields that can be used to validate CO2 forecast models by combining CO2 observations from multiple sources using ensemble Kalman filtering. We discuss a procedure to assimilate Atmospheric Infrared Sounder (AIRS) column-averaged dry-air mole fraction of CO2 (Xco2) in conjunction with meteorological observations with the coupled Local Ensemble Transform Kalman Filter (LETKF)-Community Atmospheric Model version 3.5. We examine the impact of assimilating AIRS Xco2 observations on CO2 fields by comparing the results from the AIRS-run, which assimilates both AIRS Xco2 and meteorological observations, to those from the meteor-run, which only assimilates meteorological observations. We find that assimilating AIRS Xco2 results in a surface CO2 seasonal cycle and the N-S surface gradient closer to the observations. When taking account of the CO2 uncertainty estimation from the LETKF, the CO2 analysis brackets the observed seasonal cycle. Verification against independent aircraft observations shows that assimilating AIRS Xco2 improves the accuracy of the CO2 vertical profiles by about 0.5–2 ppm depending on location and altitude. The results show that the CO2 analysis ensemble spread at AIRS Xco2 space is between 0.5 and 2 ppm, and the CO2 analysis ensemble spread around the peak level of the averaging kernels is between 1 and 2 ppm. This uncertainty estimation is consistent with the magnitude of the CO2 analysis error verified against AIRS Xco2 observations and the independent aircraft CO2 vertical profiles.

Beschreibung: Evidence for sediment transport and erosion by wind is widespread over the surface of Mars today and was likely a major geomorphic process for much of its geological past. Although Martian surface features resembling aeolian dunes and ripples have been recognized since the Mariner and Viking missions, such features have been interpreted previously as active, indurated, or exhumed sedimentary forms. Here we report evidence based on High Resolution Imaging Science Experiment images that show some megaripple forms are eroded into cohesive substrate rather than being composed of loose granular material or fossilized dunes. Exposure of stratigraphic continuity within layered, cohesive material extending crest to trough through features with mean wavelengths of 18 to 51 m demonstrates the primarily erosional formation of what we term periodic bedrock ridges (PBRs). Hence some surfaces on Mars previously considered to be covered by wind-deposited material are actually wind-carved exposures that offer windows into Martian history. PBRs lack the distinctive streamlining associated with wind-parallel yardangs and comparison of PBR orientation to yardangs, megayardangs, and active sedimentary dunes in the same vicinity confirm that these PBRs formed transverse to prevailing winds. Observed wavelengths of PBRs are comparable to those predicted by a simple model for erosional wavelengths of periodic transverse bed forms owing to the spacing of flow separations within the flow. Recognition of these transverse aeolian erosional forms brings up the question of how widespread Martian PBRs are and how many have been misinterpreted as active or indurated (fossilized) sedimentary dunes.

Beschreibung: Photolytic production rates of NO, NO2 and OH radicals in snow and the total absorption spectrum due to impurities in snowpack have been calculated for the Ocean-Atmosphere-Sea-Ice-Snowpack (OASIS) campaign during Spring 2009 at Barrow, Alaska. The photolytic production rate and snowpack absorption cross-sections were calculated from measurements of snowpack stratigraphy, light penetration depths (e-folding depths), nadir reflectivity (350–700 nm) and UV broadband atmospheric radiation. Maximum NOx fluxes calculated during the campaign owing to combined nitrate and nitrite photolysis were calculated as 72 nmol m−2 h−1 for the inland snowpack and 44 nmol m−2 h−1 for the snow on sea-ice and snowpack around the Barrow Arctic Research Center (BARC). Depth-integrated photochemical production rates of OH radicals were calculated giving maximum OH depth-integrated production rates of ∼160 nmol m−2 h−1 for the inland snowpack and ∼110–120 nmol m−2 h−1 for the snow around BARC and snow on sea-ice. Light penetration (e-folding) depths at a wavelength of 400 nm measured for snowpack in the vicinity of Barrow and snow on sea-ice are ∼9 cm and 14 cm for snow 15 km inland. Fitting scaled HULIS (HUmic-LIke Substances) and black carbon absorption cross-sections to the determined snow impurity absorption cross-sections show a “humic-like” component to snowpack absorption, with typical concentrations of 1.2–1.5 μgC g−1. Estimates of black carbon concentrations for the four snowpacks are ∼40 to 70 ng g−1 for the terrestrial Arctic snowpacks and ∼90 ng g−1 for snow on sea-ice.

Beschreibung: Seismic tomography images of the upper mantle structures beneath the Pacific Northwestern United States display a maze of high-velocity anomalies, many of which produce distorted waveforms evident in the USArray observations indicative of the Juan de Fuca (JdF) slab. The inferred location of the slab agrees quite well with existing contour lines defining the slab's upper interface. Synthetic waveforms generated from a recent tomography image fit teleseismic travel times quite well and also some of the waveform distortions. Regional earthquake data, however, require substantial changes to the tomographic velocities. By modeling regional waveforms of the 2008 Nevada earthquake, we find that the uppermost mantle of the 1D reference model AK135, the reference velocity model used for most tomographic studies, is too fast for the western United States. Here, we replace AK135 with mT7, a modification of an older Basin-and-Range model T7. We present two hybrid velocity structures satisfying the waveform data based on modified tomographic images and conventional slab wisdom. We derive P and SH velocity structures down to 660 km along two cross sections through the JdF slab. Our results indicate that the JdF slab is subducted to a depth of 250 km beneath the Seattle region, and terminates at a shallower depth beneath Portland region of Oregon to the south. The slab is about 60 km thick and has a P velocity increase of 5% with respect to mT7. In order to fit waveform complexities of teleseismic Gulf of Mexico and South American events, a slab-like high-velocity anomaly with velocity increases of 3% for P and 7% for SH is inferred just above the 660 discontinuity beneath Nevada.

Beschreibung: Particle size distributions (PSDs) of suspended particulate matters in a coastal zone are lognormal and multimodal in general. The multimodal PSD, which is caused by the mixing of multiple particle and aggregate size groups under flocculation and erosion/resuspension, is a record of the particle and aggregate dynamics in a coastal zone. Curve-fitting software was used to decompose the multimodal PSD into subordinate lognormal PSDs of primary particles, flocculi, microflocs, and macroflocs. The curve-fitting analysis for a time series of multimodal PSDs in the Belgian coastal zone showed the dependency of the multimodality on (1) shear-dependent flocculation in a flood and ebb tide, (2) breakage-resistant flocculation in the spring season, and (3) silt-sized particle erosion and advection in a storm surge. Also, for modeling and simulation purposes, the curve-fitting analysis and the settling flux estimation for the multimodal PSDs showed the possibility of using discrete groups of primary particles, flocculi, microflocs, and macroflocs as an approximation of a continuous multimodal PSD.

Beschreibung: Interferometry measurements of range spread meteor trail echoes (RSTEs; also known as nonspecular echoes) have provided new insights into both the irregularity structures in meteor trails and lower-thermospheric winds (LTWs). In this study, we used trail echoes observed with the newly installed Sanya (18.4°N, 109.6°E) 47.5 MHz VHF coherent radar and the Sanya all-sky meteor radar to estimate instantaneous zonal and hourly averaged meridional winds from RSTEs and hourly averaged zonal and meridional winds from large numbers of specular meteor echoes. The mean height variations in both the zonal and meridional winds estimated from the RSTEs were generally consistent with those estimated from specular meteor echoes below 96 km. This gives validity to the technique proposed recently by Oppenheim et al. (2009) and suggests that RSTE measurements made with a small radar can be used to investigate LTWs, whereas this had previously been limited to larger radars such as the Jicamarca radar. However, some observations show significant differences in wind magnitude at individual heights at times. The results of RSTE measurements show the presence of an intense westward wind with a speed near 100 ms−1. In contrast, the specular meteor zonal winds were generally less than 50 ms−1. On the other hand, the meridional drift of RSTEs derived from the meridional Doppler velocity at higher altitudes shows a very poor correlation with the specular meteor meridional wind. Potential causes for the discrepancy in wind estimates obtained from RSTE and specular meteor trail echoes are discussed.

Beschreibung: High precision observations during Solar Cycle 23 using the Wisconsin H-alpha Mapper (WHAM) Fabry-Perot quantify a factor of 1.5 ± 0.15 higher Balmer α column emission intensity during near-solar-maximum than during solar minimum conditions. An unresolved question is how does the observed solar cycle variation in the hydrogen column emission compare with that calculated from the hydrogen distribution in atmospheric models? We have compared WHAM solar minimum and near-solar-maximum column intensity observations with calculations using the thermospheric hydrogen density profile and background thermospheric conditions from the Mass Spectrometer Incoherent Scatter (NRLMSISE-00) empirical model extended to exospheric altitudes using the analytic exosphere model of Bishop (1991). Using this distribution, we apply the lyao_rt global resonance radiative transfer code of Bishop (1999) to calculate expected intensities that would be observed from the ground for the viewing conditions of the observations. The observed intensities are brighter than those calculated for the corresponding conditions, indicating that when MSIS is used as the thermospheric hydrogen distribution the derived intensities are too low. Additionally, both the observed and calculated WHAM hydrogen column emission intensities are higher for near-solar-maximum than for solar minimum conditions. There is better agreement between observations and intensities calculated using the evaporative analytic exosphere model at solar maximum, suggesting an underestimation of modeled satellite atoms at high altitudes. This result is consistent with sensitivity studies using the option for a quasi-exobase for satellite atoms to account for the creation of satellite orbits from charge exchange collisions.

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 6 Sarah Cornell, Cat Downy ESS2010 was the first Open Science Conference of the international collaborative initiative AIMES, and was convened and organized by QUEST, the UK's directed research programme for Earth System science. The conference showcased advances in Earth system modelling, deploying observations and process understanding to develop more quantitative and predictive understanding of the interactions of the climate system, the biosphere and the anthroposphere. These tools extend understanding of the system dynamics of biogeochemical cycles, and give perspectives on the relationships between climate, ecosystems and human needs. As Earth system science is a global research endeavour, and its remit has important societal and policy implications, a recurrent theme in the conference was the responsibility of scientists working on knowledge integration in the global environmental change context.

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 4 Ma Chun, Ju Mei-ting, Zhang Xiao-chun, Li Hong-yuan Analyses of energy consumption and carbon emissions in Tianjin are ways to understand the dynamics of developing cities in China. Using carbon emission calculation methodology recommended by IPCC, the amount of energy consumption and carbon emissions in Tianjin were calculated from 1995 to 2007. The results showed that the energy consumption structure in Tianjin relied on coal. Annual carbon emission was 26.37 million tons with growth of 4.48% per year; Sc (carbon emission per GDP) reduced year by year, and Se (carbon emission per energy consumption) decreased overall. We also proposed countermeasures to reduce carbon emissions from energy consumption.

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 10, Part B Yanhong Yan, Zhining Jia, Yulin Yang The polytetrafluroethylene (PTFE) polymer-based nanocomposites filled with nanoscale lamellar structure expanded graphite (nano-EG) and reinforced with different nanoparticles, such as nano-Al 2 O 3 , nano-copper, nano-SiO 2 and nano-TiO 2 , were prepared by using cold briquetting and hot-press sintering technologies. The quasi-static tensile experiments and dynamic mechanical thermal analysis (DTMA) were carried out. The results showed that the mechanical properties of these nanocomposites stronger depend on the variety of nanoparticles. Stress-displacement and stress relaxation curves indicate that theses composites are typical viscoelastic materials. However, due to the addition of nano-EG and other nano-particles, some composites showed relatively brittle to some extent. These research findings are believed to be helpful for providing practical guide in harsh environments.

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 11, Part C Liu Hongmin Crew's health and productivity is strongly affected by cabins’ thermal environment. This paper focuses on the numerical simulation of the indoor thermal environment in air-conditioned vessel cabins. The original airconditioning system of the cabin was analyzed. Three modified air-conditioning systems with different air-supply outlet locations and under-supply air-conditioning system were put forward for optimization. Air temperature, air velocity and PMV distribution were discussed under Airpak simulation. The results show that under-supply airconditioning system has good performance with little eddies and can contribute to energy saving. Indoor air temperature with under-supply air-conditioning system was 2∼4 lower than that °C with original air-conditioning system, leading to lower predicted mean vote (PMV).

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 8 Parvinder Singh Sandhu

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 10, Part C Xin Zhou, Ziru Lian, Jiangtao Wang, Liju Tan, Zhichao Zhao Estrogens (estrone, estradiol and estriol) and synthetic compound (ethynyl estradiol) in the water and sediment of Licun River-Jiaozhou Bay area in Qingdao were monitored. Estrogens in waters were concentrated using modified C- 18 SPE cartridges, and estrogens in sediments were extracted by liquid-solid extraction. Silane derivatives of the extracted and concentrated estrogens were analyzed by GC-MS. The concentration of estrogens ranged from ND (below the detection limit) to 180 ng/L in waters and ND to 10.8 colong/kg (dry weight) in sediment. The concentrations of estrogen in river water were higher than those in seawater during the monitoring periods. The distribution of estrogen concentration along Licun river suggested that estrogens were different with distance from the respective effluent sites. The highest concentrations were detected at station 5 which directly receives huge quantities of pollutants from adjacent rivers containing large amounts of farming and industrial wastewater.

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 9 Jean-Christophe Lata, Sébastien Barot, Gérard Lacroix The International Congress “Ecological Engineering; from concepts to applications”, Paris, was held on 2-4 December, 2009 [3]. These three days were dedicated to the exploration of new breakthroughs in ecological engineering and reflections on the way to develop the field and ground it on sound ecological and conceptual bases

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 6 Cat Downy, Sarah Cornell

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 11, Part B Shuzhou Wang, Bo Meng Neural networks with good nonlinear mapping abilities can be applied to build simulation model of helicopter. But they have some difficulties such as hardness of selecting network structure, slow convergence speed, local minimum, and over-fitting. To avoid above problems, a modeling method for dynamic nonlinear system based on support vector machine was proposed. This method was applied to build simulation model of helicopter. Compared with neural network model, SVM model possess some advantages such as simple structure, fast convergence speed and high generalization ability.

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 10, Part C Xu Shujian, Wang Tao The grain size records of loess-paleosol deposit in China are some of the most important terrestrial records of the Quaternary. It systematically carried out fieldwork on loess profile of Tuoji Island on Miaodao Islands and Changyi profile on the Laizhou Bay plain, analyzed grain size of 220 and 86 samples respectively. It shows the grain size of loess in Tuoji Island profile coarser than Changyi profile. The environment-sensitive size fractions of Tuoji Island and Changyi loess section respectively are 89.1-100.0colonm and 70.8-79.4colonm, by analyzing grain-size class vs. standard deviation values method. The changes of grain size characteristics of loess-paleosol recorded in different sections implicated the much plentiful materials in the Changyi profile on Laizhou Bay plain than Tuoji profile on Miaodao Islands.

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 11, Part C Zhiming Fang, Xiaochun Li This paper presents a preliminary assessment of the potential for CO2 geological storage in Chongqing, China. Currently, there are about 116 large stationary CO2 point emission sources which emit 85.57 MtCO2/yr totally. These stationary sources are mainly belonged to four industries: cement, power plant, iron & steel and synthetic ammonia industries. In the three kinds of geological storage formations, namely, deep saline formations (DSFs), unmineable coalbeds and depleted gas fields, the total basin-scale theoretical storage capacities of CO2 reach 24.36 Gt, equivalent to about 285 times of the annual total CO2 emissions in Chongqing. The DSFs have the largest potential storage capacity accounting for 98% of the total storage capacities. The matching results between CO2 point emission sources and candidate geological storage formations show that 94.8% of the point emission sources (accounting for 97.1% of annual total emissions) can find at least one candidate geological storage formation in its adjacent areas. This means that, for Chongqing, the CO2 transport cost is likely very low. The research findings indicate that there is great potential for CO2 geological storage technology to deploy in Chongqing and for this technology to deliver profound and sustaining impacts on reducing CO2 emissions and developing low-carbon economy in Chongqing. This preliminary study is expected to stimulate more researches, critical thinking and policy actions to promote positive measures to reduce greenhouse gas emissions so as to mitigate the impact of global climate change, as well as to set a good example for other regions in China.

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 7 M.D. Ruiz-Medina, R.M. Espejo Montes Functional Statistics provides a suitable framework for the analysis of large dimensional data sets. In this paper, we consider the spatial autoregressive functional series (SARH(1)) framework. This framework allows the incorporation of spatial interaction to the statistical analysis of functional data (see Ruiz-Medina [1] , [2] ). The SARH(1) model is fitted to the average ocean temporal temperature profiles, collected in different spatial locations, during the years 1998, 1999 and 2000. We have used the public oceanographic bio-optical database, The World-wide Ocean Optics Database (WOOD). The SARH(1) plug-in extrapolator is then computed, from the previously derived infinite-dimensional projection parameter estimator.

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 3 Fabio Sigrist, Hans R. Künsch, Werner A. Stahel A spatio-temporal model for precipitation is presented. It is assumed that precipitation follows a censored and power-transformed normal distribution. Through a regression term, precipitation is linked to covariates. Spatial and temporal dependencies are accounted for by a latent Gaussian variable that follows a Markovian temporal evolution combined with spatially correlated innovations. Such a specification allows for nonseparable covariances in space and time. Further, the Markovian structure yields computational efficiency and it exploits in a natural way the unidirectional flow of time. In addition, the model is space as well as time resolution consistent. The model is applied to three-hourly Swiss rainfall data, collected at 26 stations.

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 11, Part B Shuzhou Wang, Bo Meng Support Vector Machine (SVM) is a new modeling method. It has shown good performance in many field and mostly outperformed neural networks. The parameter selection should to be done before training SVM. Modified particle swarm optimization (POS) was adpoted to select parameters of SVM. It is shown by simulation that the modified POS algorithm can derive a set of optimal parameters of SVM. Compared with neural networks, SVM model possess some advantages such as simple structure, fast convergence speed with high generalization ability.

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 11, Part A Li Xiaonian, Zhu Yi, Zhang Fuhao, Liu Xiaodong According to domestic and foreign rural geographic information system construction, this article points out the problems of domestic new socialist countryside construction. Combined with the reality of Xinjiang new socialist countryside construction, it has constructed the geographic information platform of new socialist countryside comprehensive services, which is easier to realize farmland protection, cadastre management, central village plan and many other basic services in rural areas, and provided reliable and real-time information technology services for Xinjiang new socialist countryside construction.

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 9 Lino José Alvarez-Vázquez, Aurea Martínez, Miguel Ernesto Vázquez-Méndez, Miguel Angel Vilar The main objective of this work is showing how numerical simulation and optimal control theory can be useful tools in practical ecological engineering. We take attention into diadromous fish (salmon, trout, eel…) and their river migrations, and particularly, we focus on fishways, hydraulic structures that enable fish to overcome stream obstructions as dams or weirs. We use mathematical modelling to formulate the problems of design and management of a fishway providing a good hydraulic performance for fish. By solving these problems for a standard vertical slot fishway, we can observe that controlling the flux of inflow water is a useful technique for the management of an already built fishway, but a correct shape design is mandatory in order to guarantee a correct hydraulic performance, especially for a new fishway.

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 5 Dacheng Liu, Ning Li, Xianchun Tan, Xiaoou Yang, Li Wang, Jianbing Liu Chinese government committed to reducing carbon dioxide emissions per unit of GDP by 40% to 45% by 2020. As the capital and one of the biggest cites, Beijing expected to both keep higher GDP growth than average and cut unit GDP carbon emission, and has to adjust the relevant energy strategy in near future. The paper analysis the characteristics of energy supply and energy consumption in Beijing, and setups the economic-energy-environment-oriented reference energy system (RES), selects MARKAL as the optimal model and constructs districted multi-period linear programming matrix, which including 15 energy carriers, 4 energy processes, 17 energy conversions, and 18 energy end-use sets. Furthermore, the paper designs 11 scenarios in various pollute emission restrictions, and establishes the total economic cost as the optimize target, the low-carbon emission as main restriction, to obtain the suitable energy supply structure and end-use technology structure. At last, we have the conclusion that Beijing can attach the demands of cutting carbon emissions per unit of GDP by 45% under the scheduled GDP growth.

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 4 Elena Paoletti, Tommaso Bardelli, Gianluca Giovannini, Leonella Pecchioli The Urban Forest Effects (UFORE) model, a computer model designed to use tree allometric, air pollution and meteorological data to statistically estimate urban forest characteristics and various urban forest functions, was applied to the main park in the city of Florence, Italy (Cascine Park), in 1985 and 2004, in order to study how the natural and man-made evolution of the park affected its ability to control air quality. Plant data were for both the years, while climate and pollutant data were for year 2004 only, in order to remove the variability due to changes in the atmospheric variables. The results show that the forest growth compensated the losses due to cuttings and damages by extreme climatic events, so that the overall amount of pollutants removed from the air did not change from 1985 to 2004 (72.4–69.0 kg/ha). In contrast, the amount of carbon storing and biogenic volatile organic compound emission decreased over time, because of a reduction in the number of large trees and of isoprene-emitting individuals, but the results were very variable plot by plot. The species were ranked according to their ability of controlling air quality. These data can be used as a decision tool for establishing cuttings and new plantings in urban planning and their effects on air quality under Mediterranean climate conditions.

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 10, Part C Liu-Zhihong, Yu-Jinhui, Zhang-Deng Under the low-carbon time of globalization, Guangxi Zhuang Autonomous Region as the one of the many provinces in western China, it is necessary that to open Beibu Gulf for getting sustainable development in the new time and situation. Exactly the basic way for the development is the strategy of sustainable development that of construction Beibu Gulf economic zone consist of low-carbon, ecological and harmonious. With the development and construction of Beibu Gulf, a lot of towns are stepping into the progress of urbanization one by one. However, in the background for urbanization of ecological and low-carbon, study on low-carbon building and ecological city construction in harmonious Beibu Gulf culture that would be necessary and of great significance.

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 5 Shaoqing Chen, Bin Chen, Meirong Su The importance of addressing cumulative environmental impact of large development projects on rivers has been increasingly highlighted. Consideration to potential impact pathways may be difficult, however, without appropriate analytical methods. By introducing ecological network model, this paper focuses on the quantification of the cause-effect relationships inherent the cumulative effects of dam construction from a holistic perspective. With Lancang river of Longitudinal Range-Gorge Region (LRGR) as an example, the risk-based interaction instead of the conventional energy or material flow of ecological network model has been created to conceptualize the cumulative effects network model. Based on this model, the network structural and functional analysis were adjusted for the assessment of potential eco-environmental impact within the ecosystem, thus demonstrating how the risk-based ecological network analysis can be used to characterize the holistic cumulative effects of dams on the temporal and spatial scale.

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 7 Daniel K. Heersink, Reinhard Furrer Modern compaction rollers monitor soil properties by observing vibrational characteristics of the soil. A vibrating drum traverses the compaction site measuring soil stiffness and collecting GPS coordinates that are together termed roller measurement values (RMVs). These RMVs can be modeled as a random spatial field and additively decomposed into any sensible combination of mean terms, spatial terms, spline terms, and ridge regression terms. The goal of this modeling is to implement intelligent compaction for quality control and quality assurance purposes. Proper modeling of such data (stationarity, anisotropy,.) is then of paramount concern. Each layer of the compaction site can be modeled by the n-vector y = Xβ+α+γ+ ɛ, where Xβ is a low-order (linear) polynomial trend, α is a mean term estimated using ridge regression or splines modeling the large-scale variation, γ is a (zero-mean Gaussian) spatial process modeling the small-scale variation, and ɛ is the noise. Here, X is the (n × p) design matrix with rank p. There are many general approaches to working with such an additive mixed model, including a backfitting procedure for maximum-likelihood estimation and generalized cross-validation. Due to computational complexity of maximum-likelihood estimation a backfitting procedure, Furrer and Sain (2009) [1] , was extended to the more general models used here and employed in the estimation. The extended backfitting procedure has been shown to converge and the iterative least-squares estimates have been shown to converge to the generalized least-squares estimate. A simulation study has been conducted to analyze estimates of this general model using a penalized likelihood and generalized cross-validation (GCV) approach as well. Results of the cross-validation study using a spline structure indicate there are some random fields that can be generated that do not have a minimum GCV.

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 4 S.M. Salim, R. Buccolieri, A. Chan, S. Di Sabatino, S.C. Cheah This paper presents numerical simulations of the aerodynamic effects of trees on the flow field and dispersion of trafficoriginated pollutants in an urban street canyon of W/H = 1 with a perpendicular approach flow. Large Eddy Simulation (LES) is employed for the investigation and is validated against wind tunnel (WT) experiment. Comparisons is made between an empty street canyon and one containing avenue-like tree planting of pore volume, Pvol = 96%. In the presence of trees, both measurements and simulations show considerably larger pollutant concentrations near the leeward wall and slightly lower concentrations near the windward wall in comparison to the tree-free case.

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 10, Part B Shuo Zhou, Zongxing Chen, Xiaoyang Liu, Hao Tang In this paper we focus on augment reality (AR) used in mobile device and analysis advantages of touch-screen devices in facilitating user experience for elder people. We developed a virtual system on symbian^3 platform considering the characteristic of elder people. The assessment of the system at the end suggests the potential of mobile AR for elders.

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 6 Muhammad Afzal, Martin G. Mansell, Alexandre S. Gagnon The objective of this research is to analyse temporal changes in historic rainfall variability across Scotland using different measures of variability. The CUSUM and sequential Mann-Kendall test applied to records from 28 weather stations with up to 80 years of daily precipitation data reveal the occurrence of abrupt changes in the rainfall trends. Most weather stations show a turning point between 1978 and 1985, although some stations situated in Eastern Scotland have more than one turning point. The temporal changes in rainfall variability across Scotland are presented using a number of measures of variability.

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 9 Adil Baghli, Philippe Thiévent R&D activities at Egis Environnement (a civil engineering-based environmental consultancy) facilitated the development of OptiFlux, a spatial analysis tool designed to predict and visualize the effects of implementing a linear infrastructure upon wildlife habitats. It also tests the relevance of positioning fauna passages to ensure the restoration of habitat connectivity and therefore allows the optimization of the number and location of potential fauna passages. OptiFlux makes use of habitat quality maps which correlated with ecological requirements of each studied species. The concept is based on the evaluation of the spatial distribution of wildlife in their natural habitats. It also allows the evaluation of the impact of a project that modifies landscape structures and contributes to territory fragmentation. OptiFlux is a project optimization instrument which helps in the decisionmaking process. Major applications are: • Identification of routes with the least impact on wildlife population fluxes and their habitats, • Optimization of the number and location of fauna passages for the benefit of wildlife and reduction of the conflict points between infrastructures (road, highway, railway) and ecological networks, • Simulation of the positive effects of the proposed fauna passages or biotopes (amphibian ponds, for example) for a better choice of installations and for a better reconnection of the fragmented habitats.

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 11, Part C Zhou Yan, Jing Guang-e, Liu Xiao-hui, Li Qing-ling Theoretical research and numerical simulation for ventilation properties of solar chimney with vertical collector are performanced and they are compared with experimental results. Results show that: there are many factors to affect solar chimney ventilation that include heat collection height and width, solar radiation intensity, inlet and outlet area ratio of chimney and air inlet velocity, etc. When the collector height is increased, chimney ventilation is getting higher; but the ventilation increases slowly even decreases; the ventilation increases first and then decreases as the growing of the air layer thickness under the same chimney height and width; there exists an optimal ratio between heat collector height and width which makes the ventilation largest; considering the urban architecture image and the influence of the air layer thickness on chimney ventilation, the best air layer thickness is between 0.2m and 0.4m. Besides, the airflow temperature in solar chimney increases with chimney height in certain solar radiation intensity. It is consistent with the theoretical analysis and simulation results.

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 8

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 10, Part A Ye Yun, Xu Xi-shan, Qi Zhi-chang To protect critical resources in networked environments, it is important to quantify the likelihood of potential multi- step attacks in attack graphs. Aimed at the problems that probabilistic incorrect computing caused by shared dependencies in nodes, a methodology for security risk analysis that is based on the model of attack graphs and the Common Vulnerability Scoring System (CVSS) was presented, and the problem of probabilistic incorrect computing was solved successfully by proposing the probabilistic computing approach of accurate calculation and approximate calculation, While ensuring the accuracy of the probability of attack graph-based nodes, quickly Calculated the probability of each node, which can be adapted to a large-scale network. Reasonableness and effectiveness of proposed method was verified in the simulation. Compared with the related research, our approach can be adapted to a more complex attack graph, and had good scalability.

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 11, Part A Xin Jin, Xin Zhou Electric power enterprises are one important part of pillar industries in our country. There are many factors to cause risks which might bring trouble and disaster, so that we ought to manage those risks so as to reduce and avoid those risks, therefore we need to evaluate the risks which could happen. In this paper, in order to evaluate the risks of some thermal power enterprises in East China which are belong to one power group, we use text content analysis method to analyze a lot of risk exploration reports to build risk evaluation index system and every index’ weight, then evaluate risk level for every risk factor with AHP, and discuss the risk comprehensive evaluation of enterprises.

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 8 Suqin Li, Xue Zhang Reverse osmosis approach was used to dispose pulp and paper wastewater from a papermaking company. To meet the requirements of reverse osmosis membranes for water quality, a proper pretreatment had been done before raw water into RO membranes. A new efficient composite flocculant named PAFSSB had been used in the pre-treatment of pulp and paper wastewater. In the paper, the results showed that the treatment effect of PAFSSB was better, COD content was down to 10 mg/L and COD removal rate was up to 75%. The pre-treatment process was simplified and processing costs were reduced.

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 3 Sarah E. Nevillea, M.P. Wand We devise a variational Bayes algorithm for fast approximate inference in Bayesian Generalized Extreme Value additive model analysis. Such models are useful for flexibly assessing the impact of continuous predictor variables on sample extremes. The new methodology allows large Bayesian models to be fitted and assessed without the significant computing costs of Monte Carlo methods. © 2010 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of Alfred Stein.

Beschreibung: Publication year: 2011 Source: Procedia Environmental Sciences, Volume 10, Part A Wang Yong, Liu Yanping, Su Youpo According to the GPS data provided by International GNSS Service, the author adopted the software of GAMIT/GLOBK to solve the GPS data. The deformation of GPS stations’ coordinates during the Mw 9.0 Japan Earthquake was achieved which was utilized to infer physical processes at earthquake sources. It was computed six GPS stations’ data by GAMIT/GLOBK software and analyzed the GPS stations’ coordinate series. The changes of six stations were subsiding in the Vertical direction, while the changes of each station were moving north in the earthquake time in the North direction. The change values among KGNI, TSK2 and TSKB in North and Vertical direction reached 0.4m, or nearly 0.5m. It can be concluded that KGNI, TSK2 and TSKB were greater changes in the earthquake, which were close to the earthquake epicenter.

Beschreibung: This study evaluates the ability of the OVATION Prime auroral precipitation model to provide operational forecasts of the visible aurora. An operational implementation would primarily provide the general public with some guidance for viewing the aurora. We evaluate the likelihood that if aurorae are predicted to be visible at a location, they will be seen there within the hour. Nighttime model forecasts were validated with Polar Ultraviolet Imager data for Kp ≥ 3 and for the years 1997 and 1998. The overall forecasts for a visible aurora to occur or to not occur were correct 77% of the time. The most important prediction for public auroral viewing is that the visible aurora will occur, and these forecasts were correct 86% of the time.

Beschreibung: The oxygen isotope ratio of precipitation and tree rings is a complex function of climate variables and atmospheric dynamics, which often makes the interpretation of δ18O for palaeoclimate research challenging. Here we analyzed monthly precipitation δ18O series for 1973–2004 and annually resolved tree ring δ18O chronologies for 1945–2004 for three sites in Switzerland: one north of the Alps, one at high-elevation within the Alps, and one south of the Alps. The goal of the study was to improve the understanding of the tree ring archive by a systematic analysis of nonlocal parameters related to atmospheric circulation, in particular, geopotential height field anomalies and the frequency of synoptic weather situations, in addition to the usual local climate parameters like temperature, sunshine duration, and relative humidity. We observed that on average high-pressure situations during summer were associated with relatively high δ18O and low-pressure situations were associated with relatively low δ18O, for both the isotope ratio in precipitation and tree rings. However, correlations to the frequency of weather types were not higher than simple correlations to local temperature. Accordingly, we constructed a combined index from temperature and air pressure that proved to be a good predictor of δ18O in precipitation and used this as the source water term in a tree ring isotope fractionation model. This enabled us to use the model beyond the period where isotope values for precipitation are available, opening new perspectives in the interpretation of long tree ring δ18O chronologies.

Beschreibung: Ecology, Volume 0, Issue 0, Ahead of Print.

Beschreibung: Publication year: 2012 Source: Geoscience Frontiers Jinyang Zhang, Changqian Ma, Zhenbing She The Erlangmiao granite intrusion is located in the eastern part of the East Qinling Orogen. The granite contains almost 99 vol.% felsic minerals with accessory garnet, muscovite, biotite, zircon, and Fe-Ti oxide. Garnet is the dominant accessory mineral, shows zoned texture, and is rich in w (FeO) (14.13%–16.09%) and w (MnO) (24.21%–27.44%). The rocks have high SiO 2 , alkalis, FeO t /MgO, TiO 2 /MgO and low Al 2 O 3 , CaO with w (Na 2 O)/ w (K 2 O)〉 1. Their Rb, Ga, Ta, Nb, Y, and Yb contents are high and Sr, Ba, Eu, Zr, P, and Ti contents are low. These features indicate that the Erlangmiao granite is a highly evolved metaluminous A-type. Garnet crystallized at the expense of biotite from the MnO-rich evolved melt after fractionation of biotite, plagioclase, K-feldspar, zircon, apatite, and ilmenite. The relatively high initial 87 Sr/ 86 Sr ratios (0.706–0.708), low and negative ɛ Nd (120 Ma) values (−6.6 to −9.0), and old Nd model ages (1.5–1.7 Ga) suggest that the rocks were probably formed by partial melting of the Paleoproterozoic granitic gneisses from the basement, with participation of depleted mantle in an extensional setting. Graphical Abstract Highlights ► FeO-, MnO-rich garnet crystallized at the expense of biotite from MnO-rich granitic magma. ► Granite formed from a highly evolved metaluminous A-type magma. ► Granite magma derived through the melting of Paleoproterozoic granitic gneisses.

Beschreibung: Publication year: 2012 Source: Geoscience Frontiers Sanghoon Kwon, Gautam Mitra The map expression of “abrupt” changes in lateral stratigraphic level of a thrust fault has been traditionally interpreted to be a result of the presence of (1) a lateral (or oblique) thrust-ramp, or (2) a frontal ramp with displacement gradient, and/or (3) a combination of these geometries. These geometries have been used to interpret the structures near transverse zones in fold-thrust belts (FTB). This contribution outlines an alternative explanation that can result in the same map pattern by lateral variations in stratigraphy along the strike of a low angle thrust fault. We describe the natural example of the Leamington transverse zone, which marks the southern margin of the Pennsylvanian–Permian Oquirrh basin with genetically related lateral stratigraphic variations in the North American Sevier FTB. Thus, the observed map pattern at this zone is closely related to lateral stratigraphic variations along the strike of a horizontal fault. Even though the present-day erosional level shows the map pattern that could be interpreted as a lateral ramp, the observed structures along the Leamington zone most likely share the effects of the presence of a lateral (or oblique) ramp, lateral stratigraphic variations along the fault trace, and the displacement gradient. Graphical Abstract Highlights ► Map expression of “abrupt” changes in lateral stratigraphic level of a thrust fault. ► New interpretation along a frontal-ramp without vertical-axis rotations. ► “Abrupt” changes controlled by lateral (or oblique) ramp, stratigraphy along a fault, and displacement gradients on a frontal ramp.

Beschreibung: Publication year: 2012 Source: Geoscience Frontiers Y. Srinivas, A. Stanley Raj, D.Hudson Oliver, D. Muthuraj, N. Chandrasekar The applications of intelligent techniques have increased exponentially in recent days to study most of the non-linear parameters. In particular, the behavior of earth resembles the non-linearity applications. An efficient tool is needed for the interpretation of geophysical parameters to study the subsurface of the earth. Artificial Neural Networks (ANN) perform certain tasks if the structure of the network is modified accordingly for the purpose it has been used. The three most robust networks were taken and comparatively analyzed for their performance to choose the appropriate network. The single-layer feed-forward neural network with the back propagation algorithm is chosen as one of the well-suited networks after comparing the results. Initially, certain synthetic data sets of all three-layer curves have been taken for training the network, and the network is validated by the field datasets collected from Tuticorin Coastal Region (78°7'30"E and 8°48'45"N), Tamil Nadu, India. The interpretation has been done successfully using the corresponding learning algorithm in the present study. With proper training of back propagation networks, it tends to give the resistivity and thickness of the subsurface layer model of the field resistivity data concerning the synthetic data trained earlier in the appropriate network. The network is trained with more Vertical Electrical Sounding (VES) data, and this trained network is demonstrated by the field data. Groundwater table depth also has been modeled. Graphical Abstract Highlights ► Vertical Electrical Sounding data in the Tuticorin region has been modeled for ground water occurrence and saline water intrusion. ► Artificial Neural Network program using Feed forward back propagation algorithm gains more advantage over conventional methods. ► Error percentage on comparing with the conventional method makes the program to extend on different type of field data. ► Synthetic Memory driven model forms the frame work of the algorithm to support any kind of rough field data. ► Saline water intrusion and ground water occurrence can be very well studied with well defined sub surface structural modeling.

Beschreibung: Publication year: 2012 Source: Geoscience Frontiers Dedong Li, Yuwang Wang, Jingbin Wang, Zhaohua Luo, Jiulong Zhou, Zongfeng Yang, Cui Liu According to the metallogenic theory by transmagmatic fluid (TMF), one magmatic intrusion is a channel of ore-bearing fluids, but not their source. Therefore, it is possible to use TMF’s ability for injection into and for escaping from the magmatic intrusion to evaluate its ore-forming potential. As the ore-bearing fluids cannot effectively inject into the magmatic intrusion when the magma fully crystallized, the cooling time and rates viscosity varied can be used to estimate the minimum critical thickness of the intrusion. One dimensional heat transfer model is used to determine the cooling time for three representative dikes of different composition (granite porphyry, quartz diorite and diabase) in the Shihu gold deposit. It is also estimated the rates viscosity varied in these time interval. We took the thickness of dike at the intersection of the cooling time – thickness curve and the rates viscosity varied versus thickness curve as the minimum critical thickness. For the ore-bearing fluids effectively injecting into the magma, the minimum critical thicknesses for the three representative dikes are 33.45 m for granite porphyry, 8.22 m for quartz diorite and 1.02 m for diabase, indicating that ore-bearing dikes must be thicker than each value. These results are consistent with the occurrence of ore bodies, and thus they could be applied in practice. Based on the statistical relationship between the length and the width of dikes, these critical thicknesses are used to compute critical areas: 0.0003–0.0016 km 2 for diabase, 0.014–0.068 km 2 for quartz diorite and 0.011–0.034 km 2 for granite porphyry. This implies that ore-bearing minor intrusions have varied areas corresponding to their composition. The numerical simulation has provided the theoretical threshold of exposed thickness and area of the ore-bearing intrusion. These values can be used to determine the ore-forming potentials of dikes. Graphical Abstract Highlights ► Heat transfer and viscosity models are used to determine cooling time and viscosity variation for dikes, respectively. ► Minimum critical thicknesses of three representative dikes for ore-bearing fluid injection are computed. ► Minimum critical areas of ore-bearing dikes are estimated in view of their ratios of length/ width.

Beschreibung: Publication year: 2011 Source: Geoscience Frontiers Wei Ju, Guiting Hou, Le Li, Fangfeng Xiao This paper presents the end Late Paleozoic tectonic stress field in the southern edge of Junggar Basin by interpreting stress-response structures (dykes, folds, faults with slickenside and conjugate joints). The direction of the maximum principal stress axes is interpreted to be NW–SE (about 325°), and the accommodated motion among plates is assigned as the driving force of this tectonic stress field. The average value of the stress index R ′ is about 2.09, which indicates a variation from strike-slip to compressive tectonic stress regime in the study area during the end Late Paleozoic period. The reconstruction of the tectonic field in the southern edge of Junggar Basin provides insights into the tectonic deformation processes around the southern Junggar Basin and contributes to the further understanding of basin evolution and tectonic settings during the culmination of the Paleozoic. Graphical Abstract Highlights ► The direction of the maximum principal stress axes is interpreted to be NW–SE. ► The stress regime is a variation from strike-slip to compressive. ► The accommodated motion among plates may be the cause of this stress field.

Beschreibung: Publication year: 2011 Source: Geoscience Frontiers Liu He, Chuanlun L. Zhang, Hailiang Dong, Bin Fang, Genhou Wang Isoprenoidal glycerol dialkyl glycerol tetraethers (iGDGTs) from the Gulu hot springs (23–83.6 °C, pH 〉 7) and Yangbajing hot springs (80–128 °C, pH 〉 7) were analyzed in order to investigate the distribution of archaeal lipids among different hot springs in Tibet. A soil sample from Gulu was incubated at different temperatures and analyzed for changes in iGDGTs to help evaluate whether surrounding soil may contribute to the iGDGTs in hot springs. The sources of bacterial GDGTs (bGDGTs) in these hot springs were also investigated. The results revealed different profiles of iGDGTs between Gulu and Yangbajing hot springs. Core iGDGTs and polar iGDGTs also presented different patterns in each hot spring. The PCA analysis showed that the structure of polar iGDGTs can be explained by three factors and suggested multiple sources of these compounds. Bivariate correlation analysis showed significant positive correlations between polar and core bGDGTs, suggesting the in situ production of bGDGTs in the hot springs. Furthermore, in the soil incubation experiment, temperature had the most significant influence on concentration of bGDGTs rather than iGDGTs, and polar bGDGTs had greater variability than core bGDGTs with changing temperature. Our results indicated that soil input had little influence on the composition of GDGTs in Tibetan hot springs. On the other hand, ring index and TEX 86 values were both positively correlated with incubation temperature, suggesting that the structure of archaeal lipids changed in response to varying temperature during incubation. Graphical Abstract Highlights ► Glycerol dialkyl glycerol tetraethers (GDGTs) are determined from Tibetan hot springs and soil. ► Archaeal and bacterial GDGTs are produced in situ in the hot spring. ► Soil incubation experiments show a positive correlation between ring index or TEX 86 and incubation temperature.

Beschreibung: Ecology, Volume 0, Issue 0, Ahead of Print.

Beschreibung: A series of high resolution multibeam echo sounding surveys near San Francisco, CA suggests the occasional migration of marine sandwave crests in the direction opposite to that indicated by the shape asymmetry of the individual sandwaves, in contrast to all previous observations of the relationship between bedform shape asymmetry and migration. The anti-asymmetry migration occurs over approximately the same time period that a new sand wave crest is formed within the large and relatively stable field. The new sandwave crest appears approximately midway between two larger crests, in the vicinity of structural defects in a nearly two-dimensional portion of the field. The sandwaves in the vicinity of the new crest are found to have migrated away from the new crest regardless of their shape asymmetry. Later a large section of the new crest disappears, and the neighboring sandwaves migrated back toward the vacated crest location. This migration occurs for sandwaves up to at least ten wavelengths away from the new crest.