Uncertainty in a monthly water balance model using the generalized likelihood uncertainty estimation methodology

Journal of Earth System Science - Hydrological models are simplified representations of natural processes and subject to errors. Uncertainty bounds are a commonly used way to assess the impact of...     

A review of remote sensing methods for glacier mass balance determination

Airborne and satellite remote sensing is the only practical approach for deriving a wide area, regional assessment of glacier mass balance. A number of remote sensing approaches are possible for inferring the mass balance from some sort of proxy estimate. Here, we review the key methods relevant, in particular to Andean glaciers, discussing their strengths and weaknesses, and data sets that could be more fully exploited. We also consider future satellite missions that will provide advances in our observational capabilities. The methods discussed include observation of elevation changes, estimation of ice flux, repeat measurement of changes in spatial extent, snowline elevation and accumulation–ablation area ratio estimation. The methods are illustrated utilising a comprehensive review of results obtained from a number of studies of South American glaciers, focusing specifically on the Patagonian Icefields. In particular, we present some new results from Glaciar Chico, Southern Patagonian Icefield, Chile, where a variety of different satellite and in-situ data have been combined to estimate mass balance using a geodetic or elevation change approach over about a 25 yr period.     

Detecting filaments in the ultra-high energy cosmic ray distribution

We propose and test new statistical tools to study the distribution of cosmic rays based on the use of the minimal spanning tree. The method described is particularly sensitive to filamentary structures, as those expected to arise from strong sources of charged cosmic rays which get deflected by intervening magnetic fields. We also test the method with data available from the AGASA and SUGAR surface detector arrays.     

A field‐based investigation to examine underwater soundscapes of five common river habitats

Aquatic river habitat types have been characterized and classified for over five decades based on hydrogeomorphic and ecological variables. However, few studies considered the generation of underwater sound as a unique property of aquatic habitats, and therefore as a potential information source for freshwater organisms. In this study, five common habitat types along 12 rivers in Switzerland (six replicates per habitat type) were acoustically compared. Acoustic signals were recorded by submerging two parallel hydrophones and were analysed by calculating the energetic mean as well as the temporal variance of ten octave bands (31·5 Hz–16 kHz). Concurrently, each habitat type was characterized by hydraulic and geomorphic variables, respectively. The average relative roughness, velocity‐to‐depth ratio, and Froude number explained most of the variance of the acoustic signals created in different habitat types. The average relative roughness predominantly affected middle frequencies (63 Hz–1 kHz), while streambed sediment transport increased high‐frequency sound pressure levels (2–16 kHz) as well as the temporal variability of the recorded signal. Each aquatic habitat type exhibited a distinct acoustic signature or soundscape. These soundscapes may be a crucial information source for many freshwater organisms about their riverine environment. Copyright © 2010 John Wiley & Sons, Ltd.     

Seismic Hazard of Honduras

In this paper we have described the proceduresused, input data applied and results achieved in ourefforts to develop seismic hazard maps of Honduras.The probabilistic methodology of Cornell is employed.Numerical calculations were carried out by making useof the computer code SEISRISK III. To examine theimpact of uncertainties in seismic and structuralcharacteristics, the logic tree formalism has beenused. We compiled a de-clustered earthquake cataloguefor the region comprising 1919 earthquakes occurringduring the period from 1963 to 1997. Unified momentmagnitudes were introduced. Definition of aseismotectonic model of the whole region under review,based on geologic, tectonic and seismic information,led to the definition of seven seismogenetic zones forwhich seismic characteristics were determined. Fourdifferent attenuation models were considered. Resultsare expressed in a series of maps of expected PGA for60% and 90% probabilities of nonexceedence in a50-year interval which corresponds to return periodsof 100 and 475 years, respectively. The highest PGAvalues of about 0.4g (90% probability ofnon-exceedence) are expected along the borders withGuatemala and El Salvador.     

A computational method to help identify and measure metallines in high resolution QSO spectra

A computational code is developed to help identify metal absorption linesin high resolution QSO spectra,especially in the Lyα forest.The input to the codeincludes a list of line central wavelengths,column densities and Doppler widths.Thecode then searches for candidate metal absorption systems and assesses the probability that each system could be real.The framework of the strategy we employ isdescribed in detail and we discuss how to estimate the errors in line profile fitting thatare essential to identifi...     

Relationship between age of waste and natural electric potential generation in Sanitary Landfill

The geophysical methods are effective tools for determining changes in physical parameters of the geological environment, as soil or groundwater in the presence of contamination. This work consisted on analyzing the natural electric potential obtained over domestic solid waste ditches with controlled closure dates. The interpretation data suggest the generation of electric potential predominantly through the redox phenomenon, as opposed to the flow potential phenomenon. The statistical data analysis indicates a correlation between residence time of the waste and growing variations of voltage. In addition highlights that eight years are required to achieve the reported values for the area with absence of waste, time estimated for decomposition of most organic matter contained in the buried waste.     

Conditional versus unconditional industrial agglomeration: disentangling spatial dependence and spatial heterogeneity in the analysis of ICT firms’ distribution in Milan

A series of recent papers have introduced some explorative methods based on Ripley’s K-function (Ripley in J R Stat Soc B 39(2):172–212, 1977) analyzing the micro-geographical patterns of firms. Often the spatial heterogeneity of an area is handled by referring to a case–control design, in which spatial clusters occur as over-concentrations of firms belonging to a specific industry as opposed to the distribution of firms in the whole economy. Therefore, positive, or negative, spatial dependence between firms occurs when a specific sector of industry is seen to present a more aggregated pattern (or more dispersed) than is common in the economy as a whole. This approach has led to the development of relative measures of spatial concentration which, as a consequence, are not straightforwardly comparable across different economies. In this article, we explore a parametric approach based on the inhomogeneous K-function (Baddeley et al. in Statistica Nederlandica 54(3):329–350, 2000) that makes it possible to obtain an absolute measure of the industrial agglomeration that is also able to capture spatial heterogeneity. We provide an empirical application of the approach taken with regard to the spatial distribution of high-tech industries in Milan (Italy) in 2001.     

Identifiability analysis: towards constrained equifinality and reduced uncertainty in a conceptual model

Abstract

Different sets of parameters and conceptualizations of a basin can give equally good results in terms of predefined objective functions. Therefore, a need exists to tackle equifinality and quantify the uncertainty bands of a model. In this paper we use the concepts of equifinality, identifiability and uncertainty to propose a simple method aimed at constraining the equifinal parameters and reducing the uncertainty bands of model outputs, and obtaining physically possible and reasonable models. Additionally, the uncertainty of equifinal solutions is quantified to estimate the amount by which output uncertainty can be reduced by knowing how to discard most of the equifinal solutions of a model. As a study case, a conceptual model of the Chillán basin in Chile is carried out. From the study it is concluded that using identifiability analysis makes it possible to constrain equifinal solutions with reduced uncertainty and realistic models, resulting in a framework that can be recommended to practitioners, especially due to the simplicity of the method.     

On the viability of a certain vector-tensor theory of gravitation

A certain vector-tensor theory is revisited. Our attention is focused on cosmology. Against previous suggestions based on preliminary studies, it is shown that, if the energy density of the vector field is large enough to play the role of the dark energy and its fluctuations are negligible, the theory is not simultaneously compatible with current observations on: supernovae, the cosmic microwave background (CMB) anisotropy, and the power spectrum of the energy density fluctuations. However, for small enough energy densities of the vector field and no scalar fluctuations, the theory becomes compatible with all the above observations and, moreover, it leads to an interesting evolution of the so-called vector cosmological modes. This evolution appears to be different from that of general relativity, and the difference might be useful to explain the anomalies in the low order CMB multipoles.