Values Of Environmental Parameters Research Articles

Bayesian tracking and geoacoustic inversion

This paper describes a Bayesian approach to two related inverse problems in underwater acoustics: localizing/tracking an acoustic source when ocean environmental properties are unknown, and determining environmental properties using acoustic data from an unknown (moving) source. The goal of this work is not simply to estimate values for source and/or environmental parameters, but to determine parameter uncertainty distributions, thereby quantifying the state of knowledge and information content of the inversion. A common formulation is applied for both problems in which source parameters (location and spectrum) and environmental parameters are considered unknown random variables constrained by noisy acoustic data and by prior information on parameter values (e.g., physical limits for environmental properties) and on inter‐parameter relationships (limits on horizontal and vertical source speed). Given the strong nonlinearity of the inverse problem, marginal posterior probability densities are computed numerically using efficient Markov‐chain Monte Carlo importance sampling methods. Source tracking results are represented by joint marginal probability distributions over range and depth, integrated over unknown environmental parameters. The approach is illustrated with two examples representing tracking a quiet submerged source and geoacoustic inversion using noise from an unknown ship‐of‐opportunity. In both cases, source, seabed, and water‐column parameters are unknown.

Distribution of Large Benthic Gastropods in the Uruguayan Continental Shelf and Río de la Plata Estuary

Abstract We analyzed the distribution and ecology of large gastropods inhabiting the continental shelf of Uruguay and the Rio de la Plata estuary, in depths ranging from 4 to 62 m. Seven species belonging to Tonnidae, Ranellidae, Muricidae, Nassariidae, and Volutidae were collected. While the seven species recorded in this study have been previously reported for the Uruguayan coast, here we provide the first detailed description of its habitat preferences in terms of depth, salinity, and sea bottom temperatures. Clustering analysis of stations based on biological data (presence/ absence of species) indicated a spatial segregation of the large gastropods assemblages in three areas: estuarine, low specific richness, dominated by Rapana venosa; inshore (10 to 36 m), high richness, codominated by Zidona dufresnei and Pachycymbiola brasiliana; and offshore (21 to 62 m), intermediate richness, characterized by Z. dufresnei. Mean values for environmental parameters showed significant differences among clusters o...

A survey of the benthic microfauna (foraminifera, Ostracoda) on the Basque shelf, southern Bay of Biscay

In this work we describe by the first time the microfaunal content (foraminifers and ostracods) of the benthos of the Basque continental shelf, by studying the spatial distributions of benthic foraminifer and ostracod assemblages in relation to the environmental parameters affecting the sediments of this region of the Bay of Biscay. Most abundant benthic foraminifer species in the surface samples are Brizalina spathulata, Bulimina marginata, Cassidulina laevigata, Hyalinea balthica, Lobatula lobatula, Rosalina globularis, Textularia sagittula and Uvigerina peregrina. Most abundant and widespread ostracod species are Lindisfarnia guttata, Costa edwardsii and Pterygocythereis ceratoptera-jonesi group. Multivariate analyses (Cluster Q, R; DCA) of samples and species of these organisms have been performed to provide an accurate description of these distributions. Based on these analyses six different facies are characterised in this shelf, according to their microfaunal content as well as to the average values of environmental parameters (CaCO 3, POC, silt–clay and hypoxic biological markers). Of these facies, the eastern fringe and the mudpatch have a more pronounced hypoxic character relative to the western facies in this shelf. Results provided by benthic foraminifer and ostracod assemblages totally agree and indicate their dependence of the environmental parameters of the sediment. In the eastern area the influence of deeper waters has been detected, probably as upwelling through the canyons, evidenced by the occurrence of bathyal species of foraminifers ( Fontbotia wuellerstorfi, Hoeglundina elegans) and ostracods ( Krithe spp., Cytheropteron spp., Buntonia spp.). The noticeable oil-affection found in benthic specimens, very likely caused by the oil-spill of the “Prestige” in the benthonic environment of the Basque continental shelf, has been detected eight months after the spill. Despite the studied bathymetric range of 50 to 150 m, the depth interval of specimens affected by oil-spill is that of the outer shelf (93–150 m). Benthic microfauna evidence oil-pollution in the bottom sediments and demonstrate a wider affected area in the bottom of the Basque shelf than previously stated.

Updating urban forest inventories: An example of the DISMUT model

Canberra is a unique city in Australia where the trees on public land that dominate the urban forest were planned for at the city's inception. In the mid-1990s, a 100% census of street and park trees was completed, and together with simple health, growth and yield models, this database formed the basis of a decision information system to support the management of the urban trees – DISMUT. The accuracy of the models was evaluated in a study in 2005 where models to predict total tree height were found to be unbiased and precise, tree crown dimension were under-estimated for small trees, and tree health was over-estimated. The over-estimate of health may be due to the relatively poor rainfall conditions over the past 10 years while the biases in crown dimension predictions are more likely due to a too simple model form. However, the existence of DISMUT predictions over all streets and parks in Canberra means that statistically efficient two-phase sampling approaches can be used to correct for any bias in the mean estimates of tree numbers and size, and also to predict the mean value of other environmental, economic or social parameters of interest that are correlated to tree size.

The dynamics of sponge larvae assemblages from northwestern Mediterranean nearshore bottoms

In this study, we show for the first time the dynamics of sponge larvae assemblages from nearshore meroplankton. Plankton was collected by SCUBA diving once or twice a week during a 2-year period over a rocky artificial reef in the NW Mediterranean. Data on larval abundance were cross correlated with the values of environmental parameters (i.e. seawater temperature, solar radiation, wind speed and atmospheric pressure). In the laboratory, we recorded external features and main behaviors of larvae. We collected larvae belonging to 20 different taxa of sponges, which are among the most common in the sublittoral hard bottom communities of the NW Mediterranean and other temperate areas. There was a positive correlation between maximum abundance of larvae and highest water temperatures. Maximum solar radiation preceded the maximum of larval abundance. Wind speed showed no clear seasonal patterns and atmospheric pressure was overall the lowest when larvae were most abundant. Two main patterns in the larval release periods were observed. One was shown by species releasing larvae in summer, right before the maximum water temperatures (orders Dictyoceratida and Dendroceratida) and another by the species whose larvae release from the end of summer till autumn, when temperatures decrease (order Poecilosclerida). The larvae of Phorbas tenacior, Raphidoflus jolicoueri, Mycale rotalis, Tedania anhelans, Pleraplysilla spinifera, Aplysilla sulfurea var. rosea and Chelonaplysilla noevus are described for the first time. The larvae collected mainly belonged to the parenchymella type (except for the species Oscarella sp. and probably Cliona viridis) and showed different features and behaviors: from the elongated parenchymellae of Scopalina lophyropoda (order Halichondrida), which show simple swimming behavior and no response to light, to the parenchymellae of Poecilosclerida and Dictyoceratida orders with variable morphologies as adaptations to complex swimming behaviors. Our database will hopefully contribute to the present knowledge of larval types in sponges and definitively highlight the importance of this group in the dynamics of meroplankton from nearshore bottoms.

Early diagenesis in an organic-rich turbidite and pelagic clay sequence from the Cape Verde Abyssal Plain, NE Atlantic: magnetic and geochemical signals

Abstract Processes of early diagenesis in sediments from the Cape Verde Abyssal Plain are investigated using the complimentary techniques of environmental magnetism and solid-phase geochemistry. The sequence captured by a 2 m-long box core comprises an organic-rich turbidite derived from the NW African continental margin (emplaced ca. 330 ka BP), overlain by brown, pelagic clay. Diagenesis in the pelagic clay mainly involves slow, in-situ oxidation of the iron oxide phases present, which Mossbauer-effect data suggest are detrital haematite and magnetite (possibly maghaemitised). In the turbidite, diagenesis has proceeded in two stages: the first involving suboxic (reductive) processes, following depletion of porewater O2, and the second involving oxidative processes associated with the slow descent of an oxidation front through the bed due to diffusion of O2 from the overlying seawater. Carbonate-free magnetic parameters, interparametric quotients, and remanence acquisition, demagnetisation and coercivity measurements of the core, reveal that significant depletion of detrital ferrimagnetic iron (Fe2+/Fe3+) oxide grains like (titano)magnetite has occurred within the turbidite during suboxic diagenesis, and confirm previous suggestions that reductive dissolution of such components is a grain size-selective process. However, the higher oxidation state (Fe3+), canted-antiferromagnetic iron oxide grains like haematite and goethite are much less susceptible to reductive diagenesis. Remobilisation of transition metal ions from below the oxidation front in the turbidite has led to authigenic precipitation of ferrimagnetic Fe/Mn micronodules in a distinct layer immediately overlying the front, and above this, a further interval of Mn-enriched, “diagenetic laminae”. However, within the suboxic, organic-rich zone of the turbidite, well below the oxidation front, there is clear evidence for the presence of a significant concentration of fine (single-domain) ferrimagnetic iron oxide grains, which are most probably associated with a population of live magnetotactic bacteria. Between this zone and the oxidation front, there is a transitional interval in which the number of live magnetotactic bacteria declines rapidly, and fossil magnetosomes in the sediment are being reductively dissolved progressively up-sequence. These results are broadly similar, though differing in some respects, to magnetic and geochemical studies of hemipelagic and high-productivity pelagic sediments in which Mn- and Fe-redox boundaries have been recognised, and further illustrate the value of environmental magnetic parameters for characterising early diagenetic processes in sediments of this kind.

Integrating thermal comfort field data analysis in a case-based building simulation environment

Despite the obvious importance of thermal comfort in the design of indoor environments, it has not been effectively integrated with design support tools. The reasons can be attributed in part to an absence of modular and flexible software architecture that facilitates dynamic data transfer between building performance simulation modules. Research has shown that the mathematical models of thermal comfort sometimes fail to accurately describe or predict thermal comfort in workplace settings even when the values of environmental and personal parameters are known. Thus, there is a critical need to provide a thermal comfort evaluation framework that, in addition to the algorithmic implementation of mathematical thermal comfort prediction models, would make use of the empirical knowledge base accumulated over the last 20 years from field experiments around the world. This paper first talks about an integrated simulation environment SEMPER that allows for multiple performance evaluation including thermal comfort analysis from a shared object model of building. Then, it discusses the results of a detailed thermal comfort analysis performed to find the reasons for the discrepancy between the predicted and observed values and the factors responsible for such discrepancy. Finally, the paper shows how the results of the empirical thermal comfort analysis can be used in designing better thermal environments.

A New Approach to Statistics of Cosmological Gamma‐Ray Bursts

We use a new method of analysis to determine parameters of cosmological gamma-ray bursts (GRBs), assuming that their distribution follows the star formation history of the universe. Spectral evolution is calculated from an external shock model for fireball/blast-wave evolution and used to evaluate the measured peak flux, duration, and νFν peak photon energy for a GRB source occurring at a given redshift and with given values of total energy, baryon loading, and environmental parameters. We then fit model distributions of GRB sources to the observed peak flux, duration, and νFν peak photon energy distributions. We find that the observed width of the Ep and duration distributions cannot be explained by cosmological redshift and time dilation effects. Rather, broad distributions of total blast-wave energies and bulk Lorentz factors are necessary to explain the observed distributions simultaneously within the framework of our unifying GRB model. We discuss implications for source parameter distributions and determine a range of burst parameters consistent with the data.

Stability analysis of grey compromise programming and its application to watershed land-use planning

Multiple conflicting objectives characterize the current water resources management systems. In particular, the conflict between environmental protection of reservoir water quality and economic development by different uses of land within the reservoir watershed is a problem that receives wide attention in many developing countries. The optimal balance between carrying capacity of watershed land-use and assimilative capacity of reservoir water quality remains unclear. However, the inherent uncertainties of both environmental and economic goals and parameter values may result in additional difficulties in public decision making. This paper presents a new methodology the grey compromise programming ( GCP ) method in which the parameter uncertainties in the optimization process are specifically considered as interval numbers and the related stability theory is proved as well. The case study is drawn from the optimal planning of land-use programme in the Tweng-Wen reservoir watershed in Taiwan.

A Computer-Controlled Environmental Chamber for the Study of Aerial Fungal Spore Release

ABSTRACT An environmental chamber was designed to study aerial release of spores of ascomycetes and hyphomycetes, based on a device developed by C. M. Leach. Relative humidity (RH), temperature, red (660 nm) and infrared (880 nm) light, leaf wetness, wind speed, vibration, and rain events are controlled and monitored within the chamber via an RTC-HC11 real-time controller and data-acquisition system. A BASIC11 computer program is uploaded to and controls the system. The program requests values for environmental parameters that change through time according to user specifications. The controller interacts with a stepper motor, solenoids, and relay switches via a feedback system based on data received from solid-state RH, temperature, and leaf-wetness sensors. The data-acquisition system records environmental data from the chamber in RAM (random access memory) that can be downloaded to a personal computer for correlation with spore-release data. Spores released from fungal specimens on plant tissues and cultures placed in the chamber and subjected to the desired environmental conditions are collected on a continuous volumetric spore trap at an exhaust port from the chamber. The performance of the device was examined by measuring spore release of Mycosphaerella citri, Alternaria solani, and Venturia inaequalis under various environmental conditions.

Generic One-Compartment Model for Uptake of Organic Chemicals by Foliar Vegetation

A differential mass-balance equation for the uptake of organic chemicals into the aerial plant compartment from soil and air is derived. Processes considered are uptake from soil, gaseous deposition, volatilization from leaves, transformation and degradation, and growth. An analytical solution is developed. Chemical data needed are K Ow , K AW , and reaction rate constants. Constant average values for environmental parameters are assumed. Plant properties are typical for grass and green fodder. Calculations for 2,3,7,8-TCDD, and the comparison to a recently tested numerical four-compartment model shows the applicability of the mass-balance approach. The equation could be incorporated into existing multimedia and soil transport models and may be useful for the hazard assessment of contaminated soils.

PARAMETER SENSITIVITIES IN TWO-LAYER ISOSPEED MODELS OF SHALLOW WATER CHANNELS

Sensitivities of relative intensity, interference wavelength, and horizontal wave number predictions to input parameters in two-layer isospeed models of shallow-water, low-frequency (less than 100 Hz) acoustic propagation problems are examined. The investigation is directed toward environmental parameter values corresponding generally to those near the site of a recent New Jersey shelf experiment. Typical parameter uncertainties in the environment of the experiment site are used to determine effects of parameter sensitivities on the accuracy of propagation model predictions. Also, analytic expressions for rates of change of wave numbers with respect to parameters are used to compute wave number and interference wavelength changes caused by parameter variations corresponding to the uncertainties. It is found that channel depth variations cause the largest change in intensity, while water sound speed variations have the greatest effect on wave numbers. Variabilities of the parameter sensitivities in regions about the base parameter sets are also examined, with the rates of change generally staying of the same order of magnitude throughout the regions considered. However, wave numbers which are close to cutoff can produce rates of change which vary by as much as three orders of magnitude.

Minimizing Total Cost in Scheduling Outpatient Appointments

This paper considers various rules for scheduling appointments for medical clinic outpatients and investigates their ability to minimize a weighted sum of medical personnel's and patients' idle-time costs. It is shown that the idle times incurred by any given rule are affected by the following three “environmental factors” (in decreasing order of importance): the probability of no-show, the coefficient of variation of service times, and the number of patients per clinical session. Theoretically, an appropriate scheduling rule can be identified only if one knows the values of these parameters and the ratio between the medical personnel's and patients' idle-time costs. Under environments characterized by 27 different combinations of the three environmental factors, the performance of nine scheduling rules are evaluated using simulation. Some of the rules evaluated are original to this study. The results are presented in the form of “efficient frontiers,” together with a simple procedure for identifying the best scheduling rule for given environmental-parameter values. This rule-identification procedure is shown to be easily adaptable for circumstances with limited knowledge about the environmental factors; it also reveals that the simple Bailey-Welch individual-appointment rules are surprisingly robust.

Estimation of sea-surface wind speed from whitecap cover: statistical approaches compared empirically and by simulation

Abstract In this paper, the possibility of predicting sea-surface wind speed, given values for whitecap cover and other environmental parameters, is examined. The performance of a number of different techniques of statistical calibration is evaluated in relation to four data sets. The performance of the methods is also examined when they are applied to simulated data sets; robustness is a particular concern. Some general conclusions are drawn in relation to which of the methods are to be recommended for use.

Comments on paper ‘estimating return values of environmental parameters’ by D. J. T. Carter and P. G. Challenor (Q. J. January 1981,107,259–266)

Comments on paper ‘estimating return values of environmental parameters’ by D. J. T. Carter and P. G. Challenor (Q. J. January 1981,107,259–266)

Lasers as probes for air and sea

Abstract The rapid development of quantum electronics has permitted the introduction of efficient remote-sensing techniques for air and sea, based on applied laser spectroscopy. In this paper basic interactions between laser light and molecules are discussed as a background for a description of laser probing of the atmosphere and the hydrosphere. For the atmosphere both meteorological parameters and pollution levels can be measured. Long-path absorption and lidar (laser radar) techniques yield average or range-resolved values for several environmental parameters. Tropospheric and stratospheric measurements of particles and gaseous pollutants are described. Laser light can be used for marine probing within the blue-green optical window of water. Much of the effort in this field aims at the development of airborne measuring systems. Bathymetric experiments and the detection of schools of fish are discussed. Laser-induced fluorescence can be used for airborne monitoring of pollutants like mineral oils and pu...

Genetic Differences and Environments of Mussel Populations in the Maritime Provinces

Genetic differences among Mytilus edulis populations from four localities in Atlantic Canada were examined using electrophoretic techniques. On the basis of allele frequency distributions at four loci (LAP-1, PEPTIDASE-2, PGI, PGM), the localities fell into two pairs, paralleling a similar pairing on the basis of values of specific environmental parameters and their variability. Gene flow between environments could be eliminated as an explanation of gene frequency similarity in one of the pairs. The large heterozygote deficiencies appear not to be satisfactorily explained by the Wahlund effect, inbreeding, or "silent alleles," without the added influence of environmental selection. We conclude that the allele frequency patterns reflect differences in the average environmental characteristics among localities.Key words: isoenzymes, blue mussels, genetic differences, environmental selection, Mytilus edulis

Carbon dioxide and climate: an astrophysical perspective

In this survey the earth is viewed from the astrophysical perspective, i.e. using global mean values of environmental parameters. The role of carbon dioxide is described in the processes of energy transfer from the earth's surface to space, which determine “global climate” as measured by the mean surface temperature. Analogies and differences between the problems of the terrestrial atmosphere and those of the solar and stellar atmospheres are examines, both in the computation of model atmosphere and in remote sensing of atmospheric temperature and composition. Subsequently, the temporal astrophysical perspective, with a review of the evolution of CO 2 abundance and climate on astrophysical or geological time scales, on earth as on Venus (the runaway greenhouse) and on Mars is introduced. Variation of CO 2 may have been critical to the maintenance of an environment in which life could originate and evolve, and may itself have been affected by life. On human time scales, the recent and continuing increase in atmospheric CO 2 raises new problems, which are briefly surveyed. It is argued, that the differential greenhouse effect of increased CO 2 in the earth's atmosphere is essentially identical to the “blanketing effect” of spectral lines on the temperature structure of stellar atmospheres. The methods used by astrophysicists in such studies are reviewed and compared with those used to evaluate the differential greenhouse effect of CO 2 in radiative-convective models of the earth's atmosphere. The latter methods remain relatively crude, but recent results by different authors are in reasonably good agreement; however, the astrophysical perspective, i.e. the use of one-dimensional global mean models, remains a gross simplification of the real complexity of the earth's climate system, which is also true in stellar atmospheres.

Distribution of certain soil inhabiting chytrid and chytridiaceous species related to some physical and chemical factors

Most ecological studies of chytrids and chytridiaceous fungi in soils are primarily distributional, and autecological information for particular species is scant. In this study the distribution of 11 species, Schizochytrium aggregatum, Thraustochytrium roseum, Chytriomyces hyalinus, Rhizophlyctis harderi, Rhizophydium sp. (utriculare?), R. sphaerocarpum, R. carpophilum, R. sphaerotheca, Phlyctochytrium chaetiferum, P. palustre, and P. reinboldtae, is numerically expressed by an index (DII) derived from occurrence and frequency for 19 habitats. Mean values of various environmental parameters—pH, organic matter, bulk density, osmolarity, Ca2+, Mg2+, and Na+—are calculated for each habitat, and linear correlations of DII against means of the environmental factors of each habitat are calculated for each species. Also the range, mean, and standard deviation of chemical and physical parameters at sites where each species occurs are calculated. By these methods some autecological facts appear for each species. Basically the fungi are divisible into four groups: (1) obligately marine, S. aggregatum; (2) marine, T. roseum; (3) facultatively marine, C. hyalinus, R. harderi, R. sphaerocarpum, P. chaetiferum, R. carpophilum, R. sphaerotheca, Rhizophydium sp. (utriculare?); and (4) marine occasionals, P. palustre, P. reinboldtae. Problematic aspects of the study are discussed and another line of investigation is proposed.

Plasma Considerations in Space Communications

Since space mission success depends heavily upon radio frequency link with Earth, the characteristics of plasma as a propagation medium are vital in telecommunication system design. This paper presents general discussion and develops an analytic methodology to identify propagation difficulties and anomalies caused by characteristic plasma behavior. A typical space mission requirement is outlined, values of pertinent environmental parameters are obtained or estimated, and the results are compared with observed data and the correlations discussed.