scholarly journals Technical note: Fourier approach for estimating the thermal attributes of streams

2016 ◽  
Author(s):  
Masahiro Ryo ◽  
Marie Leys ◽  
Christopher T. Robinson
Keyword(s):  
Analytical Method ◽  
Methodological Approach ◽  
Stream Temperature ◽  
Technical Note ◽  
Swiss Alps ◽  
Diel Periodicity ◽  
Seasonal Periodicity ◽  
Relative Contribution ◽  
Spatio Temporal ◽  
Recorded Temperature

Abstract. Temperature models that directly predict ecologically important thermal attributes across spatio-temporal scales are still poorly developed. This study developed an analytical method to estimate seasonal and diel periodicities as well as irregularities in stream temperature at data-poor sites based on Fourier analysis. We first quantified the thermal attributes of a glacier-fed stream in the Swiss Alps using 2-years of hourly-recorded temperature. Stream temperature was accurately decomposed to an average 3.8 °C, diel periodicity spanning 4.9 °C, seasonal periodicity spanning 7.5 °C, and an irregularity having an average of 0.0 °C but spanning 9.7 °C. These thermal attributes then were used to estimate thermal attributes at spot-measured sites along the river, resulting in a different relative contribution (weighting) of attributes among sites. The results confirm that the developed method can infer stochastic behaviors in stream thermal attributes at spot-measured sites. Additional ways to further improve the methodological approach are discussed.

scholarly journals Technical note: Fourier approach for estimating the thermal attributes of streams

2016 ◽  
Vol 20 (8) ◽  
pp. 3411-3418 ◽  
Author(s):  
Masahiro Ryo ◽  
Marie Leys ◽  
Christopher T. Robinson
Keyword(s):  
Fourier Analysis ◽  
Thermal Characteristics ◽  
Stream Temperature ◽  
Technical Note ◽  
Swiss Alps ◽  
Diel Periodicity ◽  
Seasonal Periodicity ◽  
Average Temperature ◽  
Poor Site ◽  
Periodic Components

Abstract. Temperature models that directly predict ecologically important thermal attributes across spatiotemporal scales are still poorly developed. This study developed an analytical method based on Fourier analysis to estimate seasonal and diel periodicities, as well as irregularities in stream temperature, at data-poor sites. The method extrapolates thermal attributes from highly resolved temperature data at a reference site to the data-poor sites on the assumption of spatial autocorrelation. We first quantified the thermal attributes of a glacier-fed stream in the Swiss Alps using 2 years of hourly recorded temperature. Our approach decomposed stream temperature into its average temperature of 3.8 °C, a diel periodicity of 4.9 °C, seasonal periodicity spanning 7.5 °C, and the remaining irregularity (variance) with an average of 0.0 °C but spanning 9.7 °C. These attributes were used to estimate thermal characteristics at upstream sites where temperatures were measured monthly, and we found that a diel periodicity and the variance strongly contributed to the variability at the sites. We evaluated the performance of our predictive mechanism and found that our approach can reasonably estimate periodic components and extremes. We could also estimate the variability in irregularity, which cannot be represented by other techniques that assume a linear relationship in temperature variabilities between sites. The results confirm that spatially extrapolating thermal attributes based on Fourier analysis can predict thermal characteristics at a data-poor site. The R scripts used in this study are available in the Supplement.

scholarly journals Technical Note: Quantification of interferences of wet chemical HONO LOPAP measurements under simulated polar conditions

2008 ◽  
Vol 8 (22) ◽  
pp. 6813-6822 ◽  
Author(s):  
J. Kleffmann ◽  
P. Wiesen
Keyword(s):  
Technical Note ◽  
Swiss Alps ◽  
Pollution Level ◽  
Research Station ◽  
Polar Regions ◽  
Alpine Research ◽  
Absorption Photometer ◽  
Present Pilot Study ◽  
Good Agreement

Abstract. In the present pilot study, an optimized LOPAP instrument (LOng Path Absorption Photometer) for the detection of nitrous acid (HONO) in the atmosphere (DL 0.2 pptV) was tested at the high alpine research station Jungfraujoch at 3580 m altitude in the Swiss Alps under conditions comparable to polar regions. HONO concentrations in the range <0.5–50 pptV with an average of 7.5 pptV were observed at the Jungfraujoch. The diurnal profiles obtained exhibited clear maxima at noon and minima with very low concentration during the night supporting the proposed photochemical production of HONO. In good agreement with recent measurements at the South Pole, it was demonstrated, that interferences of chemical HONO instruments can significantly influence the measurements and lead to considerable overestimations, especially for low pollution level. Accordingly, the active correction of interferences is of paramount importance for the determination of reliable HONO data.

scholarly journals Technical Note: Using wavelet analyses on water depth time series to detect glacial influence in high-mountain hydrosystems

2013 ◽  
Vol 10 (4) ◽  
pp. 4369-4395 ◽  
Author(s):  
S. Cauvy-Fraunié ◽  
T. Condom ◽  
A. Rabatel ◽  
M. Villacis ◽  
D. Jacobsen ◽  
...  
Keyword(s):  
Time Series ◽  
Water Depth ◽  
Water Pressure ◽  
Methodological Approach ◽  
Technical Note ◽  
High Mountain ◽  
Tropical Andes ◽  
Glacial Meltwater ◽  
Depth Measurement ◽  
Wavelet Analyses

Abstract. Worldwide, the rapid shrinking of glaciers in response to ongoing climate change is currently modifying the glacial meltwater contribution to hydrosystems in glacierized catchments. Assessing the contribution of glacier run-off to stream discharge is therefore of critical importance to evaluate potential impact of glacier retreat on water quality and aquatic biota. This task has challenged both glacier hydrologists and ecologists over the last 20 yr due to both structural and functional complexity of the glacier-stream system interface. Here we propose a new methodological approach based on wavelet analyses on water depth time series to determine the glacial influence in glacierized catchments. We performed water depth measurement using water pressure loggers over ten months in 15 stream sites in two glacier-fed catchments in the Ecuadorian Andes (> 4000 m). We determined the global wavelet spectrum of each time series and defined the Wavelet Glacier Signal (WGS) as the ratio between the global wavelet power spectrum value at a 24 h-scale and its corresponding significance value. To test the relevance of the WGS we compared it with the percentage of the glacier cover in the catchments, a metric of glacier influence often used in the literature. We then tested whether one month data could be sufficient to reliably determine the glacial influence. As expected we found that the WGS of glacier-fed streams decreased downstream with the increasing of non-glacial tributaries. We also found that the WGS and the percentage of the glacier cover in the catchment were significantly positively correlated and that one month data was sufficient to identify and compare the glacial influence between two sites, provided that the water level time series were acquired over the same period. Furthermore, we found that our method permits to detect glacial signal in supposedly non-glacial sites, thereby evidencing glacial meltwater infiltrations. While we specifically focused on the tropical Andes in this paper, our approach to determine glacier influence would be applicable to temperate and arctic glacierized catchments. The WGS therefore appears as a powerful and cost effective tool to better understand the hydrological links between glaciers and hydrosystems and assess the consequences of rapid glacier melting.

scholarly journals Technical Note: Improving computational efficiency in large linear inverse problems: an example from carbon dioxide flux estimation

2012 ◽  
Vol 5 (4) ◽  
pp. 3325-3342
Author(s):  
V. Yadav ◽  
A. M. Michalak
Keyword(s):  
Carbon Dioxide ◽  
Inverse Problems ◽  
Computational Efficiency ◽  
Optimization Problems ◽  
Temporal Distribution ◽  
Carbon Dioxide Flux ◽  
Technical Note ◽  
Sensitivity Matrix ◽  
Direct Computation ◽  
Spatio Temporal

Abstract. Addressing a variety of questions within Earth science disciplines entails the inference of the spatio-temporal distribution of parameters of interest based on observations of related quantities. Such estimation problems often represent inverse problems that are formulated as linear optimization problems. Computational limitations arise when the number of observations and/or the size of the discretized state space become large, especially if the inverse problem is formulated in a probabilistic framework and therefore aims to assess the uncertainty associated with the estimates. This work proposes two approaches to lower the computational costs and memory requirements for large linear space-time inverse problems, taking the Bayesian approach for estimating carbon dioxide (CO2) emissions and uptake (a.k.a. fluxes) as a prototypical example. The first algorithm can be used to efficiently multiply two matrices, as long as one can be expressed as a Kronecker product of two smaller matrices, a condition that is typical when multiplying a sensitivity matrix by a covariance matrix in the solution of inverse problems. The second algorithm can be used to compute a posteriori uncertainties directly at aggregated spatio-temporal scales, which are the scales of most interest in many inverse problems. Both algorithms have significantly lower memory requirements and computational complexity relative to direct computation of the same quantities (O(n2.5) vs. O(n3)). For an examined benchmark problem, the two algorithms yielded a three and six order of magnitude increase in computational efficiency, respectively, relative to direct computation of the same quantities. Sample computer code is provided for assessing the computational and memory efficiency of the proposed algorithms for matrices of different dimensions.

scholarly journals Spatially mismatched trophic dynamics: cyclically outbreaking geometrids and their larval parasitoids

2010 ◽  
Vol 6 (4) ◽  
pp. 566-569 ◽  
Author(s):  
Snorre B. Hagen ◽  
Jane U. Jepsen ◽  
Tino Schott ◽  
Rolf A. Ims
Keyword(s):  
Trophic Interactions ◽  
Travelling Waves ◽  
Methodological Approach ◽  
Spatial Dynamics ◽  
Population Cycles ◽  
Trophic Levels ◽  
Trophic Dynamics ◽  
Spatial Mismatch ◽  
Larval Parasitoids ◽  
Spatio Temporal

For trophic interactions to generate population cycles and complex spatio-temporal patterns, like travelling waves, the spatial dynamics must be matched across trophic levels. Here, we propose a spatial methodological approach for detecting such spatial match–mismatch and apply it to geometrid moths and their larval parasitoids in northern Norway, where outbreak cycles and travelling waves occur. We found clear evidence of spatial mismatch, suggesting that the spatially patterned moth cycles in this system are probably ruled by trophic interactions involving other agents than larval parasitoids.

scholarly journals Is Happiness Linked to Subjective Life Expectancy? A Study of Chilean Senior Citizens

Mathematics ◽  
2021 ◽  
Vol 9 (17) ◽  
pp. 2050
Author(s):  
Gregorio Gimenez ◽  
Ana Isabel Gil-Lacruz ◽  
Marta Gil-Lacruz
Keyword(s):  
Life Expectancy ◽  
Social Protection ◽  
Senior Citizens ◽  
Methodological Approach ◽  
Active Ageing ◽  
Ageing Population ◽  
Social Agents ◽  
Scarce Resources ◽  
Relative Contribution ◽  
The People

The main goal of this research is to determine the link between happiness and individual subjective life expectancy (SLE) among Chilean senior citizens. We use data from the 2015 edition of the Chilean Social Protection Survey. Our sample consists of 1298 seniors: 700 aged 65–74, 421 aged 75–84, and 177 aged 85 and older. We provide a novel methodological approach that allows us to measure the relative contribution of happiness to SLE, by combining the Shapley–Owen–Shorrocks decomposition with contrasts of marginal linear predictions of the equality of the means by groups. Results reveal that happiness is the most important determinant of seniors’ SLE, and the effect is stronger the older the people are. Addressing varying levels of happiness is important because both happiness and unhappiness have a significant impact. In an ageing population, social agents should consider that these variables (happiness and SLE) are related to engagement in healthy lifestyles. If prevention programs integrated this interaction, welfare systems could save scarce resources. Therefore, governments should foster happiness to support active ageing.

scholarly journals Technical Note: Coupling of chemical processes with the Modular Earth Submodel System (MESSy) submodel TRACER

2007 ◽  
Vol 7 (6) ◽  
pp. 17069-17097
Author(s):  
P. Jöckel ◽  
A. Kerkweg ◽  
J. Buchholz ◽  
H. Tost ◽  
R. Sander ◽  
...  
Keyword(s):  
Chemical Species ◽  
Positive Definiteness ◽  
Technical Note ◽  
Integration Scheme ◽  
Rounding Errors ◽  
Specific Chemical ◽  
Additional Information ◽  
Spatio Temporal ◽  
Limited Precision ◽  
Specific Species

Abstract. The implementation of processes related to chemistry into Earth System Models and their coupling within such systems requires the consistent description of the chemical species involved. We provide a tool (written in Fortran95) to structure and manage information about constituents, herein after referred to as tracers, namely the Modular Earth Submodel System (MESSy) generic (i.e., infrastructure) submodel TRACER. With TRACER it is possible to define a multitude of tracer sets, depending on the spatio-temporal representation (i.e., the grid structure) of the model. The required information about a specific chemical species is split into the static meta-information about the characteristics of the species, and its (generally in time and space variable) abundance in the corresponding representation. TRACER moreover includes two submodels. One is TRACER_FAMILY, an implementation of the tracer family concept. It distinguishes between two types: type-1 families are usually applied to handle strongly related tracers (e.g., fast equilibrating species) for a specific process (e.g., advection). In contrast to this, type-2 families are applied for tagging techniques, in which specific species are artificially decomposed and associated with additional information, in order to conserve the linear relationship between the family and its members. The second submodel is TRACER_PDEF, which corrects and budgets numerical negative overshoots that arise in many process implementations due to the numerical limitations (limited precision, rounding errors). The submodel therefore guarantees the positive definiteness of the tracers and stabilises the integration scheme. As a by-product, it further provides a global tracer mass diagnostic. Last but not least, we present the submodel PTRAC for the definition of prognostic tracers via a Fortran95 namelist. TRACER with its submodels and PTRAC can readily be applied to a variety of models without further requirements. The code and a documentation is included in the electronic supplement.

Assessment of safety and risk of flooding of urban industrial territories: expert-analytical method

2021 ◽  
pp. 16-23
Author(s):  
Н.П. Куранов ◽  
Е.А. Тимофеева
Keyword(s):  
Analytical Method ◽  
Methodological Approach ◽  
State Standards ◽  
Natural Processes ◽  
Main Factors ◽  
Local Levels

Изложены основные положения экспертно-аналитического метода оценки риска опасных процессов, который лег в основу разработки ряда методических рекомендаций и государственных стандартов. На базе этого метода предложена методика оценки безопасности и риска одного из опасных природно-техногенных процессов – подтопление градопромышленных территорий. Указаны основные факторы вредного воздействия этого процесса на объекты, находящиеся на таких территориях. Показано, как риски и ущербы от подтопления градопромышленных территорий могут оцениваться на основе общего методологического подхода к оценке рисков от опасных техноприродных процессов. В результате получены критерии безопасности и риска от подтопления и разработан механизм оценки риска от подтопления. Выявлены особенности выполнения оценок риска от подтопления градопромышленных территорий на федеральном, региональном и локальном уровнях. The main provisions of the expert-analytical method for assessing the risk of hazardous processes are stated; the method formed the basis for the development of a number of methodological recommendations and state standards. On the basis of this method, a technique is proposed for assessing the safety and risk of one of the dangerous natural-technogenic processes – flooding of urban industrial territories. The main factors of the harmful impact of this process on the structures located in such territories are indicated. It is shown how risks and damages from flooding of urban industrial territories can be estimated on the basis of the general methodological approach to assessing risks from hazardous techno-natural processes. As a result, criteria for safety and risk of flooding were obtained and a mechanism for assessing the risk of flooding was developed. The features of the assessment of the risk from flooding of urban industrial territories at the federal, regional and local levels are revealed.

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