Statistical tests for regional seismic phase characterizations   总被引：1，自引：0，他引：1  

L. Persson 《Journal of Seismology》2003,7(1):19-33

In seismic analysis some assumptions are often made aboutthe data, e.g. stationarity and Gaussianity. This is not obvious for all realseismic data. Here, we use statistical tests for characterization of regionalseismic data. We apply tests for stationarity, symmetry, linearity, andtime-reversibility. In the analysis we use twelve regional seismic events inFennoscandia recorded with the seismic small-aperture arrays NORESS,ARCESS and FINESA at hypocentral distances in the range from 160 to1580 km. For the tests we use the regional phases Pn, secondary P, Sn and Lg-phases and the preceding noise. Two of the eventsare explosions, two are rockbursts and eight are earthquakes. Theperformance and possibilities of using statistical tests based on bispectra, asa complementary tool for conventional analysis of seismic phases isdemonstrated. The preceding noise recorded before the first onset of theP-wave for the twelve events is tested to be spatially stationarybetween each channel within each array and temporal stationary in 21consecutive time windows of 3.2 sec each. Also, the preceding noise issymmetric and linear. The seismic phases defined by the symmetry test asnon-Gaussian (not symmetric) are all linear. This means a linear model canbe used to characterize both the noise and the phases. The first P-phase for the two explosions is characterized as non-Gaussian at thethree arrays. For all 36 possibly first P-phase arrivals at the three arraystations, 23 are non-Gaussian. The second P-phase is non-Gaussian at13 of 36 data records, the S-phase at eleven of 36 and the Lg-phase at nine of 36. For all the four phases more than 32 of possible36 are time-reversible.  相似文献   

Differential nocturnal cooling in the landscape detected by mobile measurements     

P. Persson 《Theoretical and Applied Climatology》1997,56(3-4):215-224

Summary In June 1986 mobile air temperature measurements were performed in the Kivik area in Sweden. The measuring trips were repeated each hour during a night with calm and clear weather conditions. Along a loop, 8650 m long and traversing a hilly landscape, the air temperature was measured at four levels (0.2, 1.0, 2.0 and 3.0 m a g). In this study the results are focused on the measurements at the standard level, 2.0 m a g, in order to make it easier to compare this study with earlier mobile studies.Sudden rises in air temperature at 2.0 m occurred at a number of elevated locations along the loop, at a max. rate of 3.5°C/hour, indicative of the influence of dynamic turbulence. Lower parts of the loop did show a drop in air temperature at the same time, with a max. of 3.8°C/hour, indicative of cold air influence. In most earlier studies the mobile measurements were compensated for the nocturnal cooling in order to make it possible to directly compare the different measurement points. This study highlights the problems due to turbulence as mentioned above. It also stresses the fact that more reference measurements at more than one point along a loop are needed in hilly terrain.With 7 Figures  相似文献   

Industrial minerals and rocks, aggregates and natural stones in the Nordic countries     

Kurt Johansson Rune B. Larsen Markku J. Lehtinen Lars Persson Mika Raeisaenen Stig A. Schack Pedersen Paer Weihed Nils-Gunnar Wik 《《幕》》2008,31(1):133-139

The Nordic countries, including Greenland, have a long tradition in mining. The industrial minerals sector is expanding in most Nordic countries and extensive development has taken place during the last few years. The main commodities mined are carbonate rocks, quartz, feldspar, apatite, olivine and talc.
A number of diferent types of dimension stones are quarried in all countries. Rock aggregates are increasingly important, replacing sand and gravel aggregate as construction materials in some countries due to the need to protect ground water supplies.  相似文献   

Equity and efficiency in adaptation finance: initial experiences of the Adaptation Fund     

Asa Persson  Elise Remling 《Climate Policy》2013,13(4):488-506

The Adaptation Fund, established under the Kyoto Protocol of the United Nations Framework Convention on Climate Change (UNFCCC), has now been approving funding for adaptation projects for more than two years. Given its particular institutional status and specific focus on concrete adaptation, it is particularly relevant to study the initial experiences of it for any future upscaling of international adaptation finance, despite the fact that its own resources are getting scarce. Alternative rationales for allocating funds, based on equity and efficiency concerns at both international and subnational levels, are here tested against the criteria and priorities of the Fund and decisions made on project approval. It is concluded that equity concerns appear to be the primary motivation and that allocation is de facto made between states rather than by considering inequity between subnational communities. However, the currency of vulnerability for determining equitable outcomes in allocation decisions has not been formalized, despite its central importance to the Fund. Instead, uniform national caps have been introduced. Such an equality approach can be considered inequitable. Finally, it is noted that although the Adaptation Fund Board has continuously developed its proposal review practices and adopted a learning-by-doing approach, it should provide both a further specification of the evaluation criteria and a compilation of best practices from approved proposals, and moreover enhance the transparency of the review process, all of which would clarify its core priorities for current and future project proponents.  相似文献   

Calorimetric study of the thermodynamics of formation of MgSO4 and NaSO4− ion pairs at the ionic strength of seawater     

Olof Johansson  Ingmar Persson  Margareta Wedborg 《Marine Chemistry》1980,8(3):191-198

The formation of the ion pairs MgSO₄ and NaSO₄^? was investigated calorimetrically at 0.75 M ionic strength, 25°C, 1 atm. Simultaneous determinations of enthalpy changes, ΔH₁⁰, and stability constants, K₁, were not possible, and values of K₁ determined independently had to be introduced for the calculation of ΔH₁⁰. The values of ΔH₁⁰ obtained were 1–3 kJ mol^?1 for MgSO₄ and 0 kJ mol^?1 for NaSO₄^?.  相似文献   

Uncertainty and learning: implications for the trade-off between short-lived and long-lived greenhouse gases   总被引：1，自引：1，他引：0  

Daniel J. A. Johansson  U. Martin Persson  Christian Azar 《Climatic change》2008,88(3-4):293-308

The economic benefits of a multi-gas approach to climate change mitigation are clear. However, there is still a debate on how to make the trade-off between different greenhouse gases (GHGs). The trade-off debate has mainly centered on the use of Global Warming Potentials (GWPs), governing the trade-off under the Kyoto Protocol, with results showing that the cost-effective valuation of short-lived GHGs, like methane (CH₄), should be lower than its current GWP value if the ultimate aim is to stabilize the anthropogenic temperature change. However, contrary to this, there have also been proposals that early mitigation mainly should be targeted on short-lived GHGs. In this paper we analyze the cost-effective trade-off between a short-lived GHG, CH₄, and a long-lived GHG, carbon dioxide (CO₂), when a temperature target is to be met, taking into consideration the current uncertainty of the climate sensitivity as well as the likelihood that this will be reduced in the future. The analysis is carried out using an integrated climate and economic model (MiMiC) and the results from this model are explored and explained using a simplified analytical economic model. The main finding is that the introduction of uncertainty and learning about the climate sensitivity increases the near-term cost-effective valuation of CH₄ relative to CO₂. The larger the uncertainty span, the higher the valuation of the short-lived gas. For an uncertainty span of ±1°C around an expected climate sensitivity of 3°C, CH₄ is cost-effectively valued 6.8 times as high as CO₂ in year 2005. This is almost twice as high as the valuation in a deterministic case, but still significantly lower than its GWP₁₀₀ value.  相似文献   

Electromagnetic induction prediction of soil salinity and groundwater properties in a Tunisian Saharan oasis     

F. Bouksila  M. Persson  A. Bahri  R. Berndtsson 《水文科学杂志》2013,58(7):1473-1486

Abstract

Electromagnetic induction measurements (EM) were taken in a saline gypsiferous soil of the Saharan-climate Fatnassa oasis (Tunisia) to predict the electrical conductivity of saturated soil extract (ECe) and shallow groundwater properties (depth, Dgw, and electrical conductivity, ECgw) using various models. The soil profile was sampled at 0.2 m depth intervals to 1.2 m for physical and chemical analysis. The best input to predict the log-transformed soil salinity (lnECe) in surface (0–0.2 m) soil was the EMh/EMv ratio. For the 0–0.6 m soil depth interval, the performance of multiple linear regression (MLR) models to predict lnECe was weaker using data collected over various seasons and years (R _a ² = 0.66 and MSE = 0.083 dS m^-1) as compared to those collected during the same period (R _a ² = 0.97, MSE = 0.007 dS m^-1). For similar seasonal conditions, for the Dgw–EMv relationship, R ² was 0.88 and the MSE was 0.02 m for Dgw prediction. For a validation subset, the R ² was 0.85 and the MSE was 0.03 m. Soil salinity was predicted more accurately when groundwater properties were used instead of soil moisture with EM variables as input in the MLR.

Editor D. Koutsoyiannis; Associate editor K. Heal

Citation Bouksila, F., Persson, M., Bahri, A., and Berndtsson, R., 2012. Electromagnetic induction predictions of soil salinity and groundwater properties in a Tunisian Saharan oasis. Hydrological Sciences Journal, 57 (7), 1473–1486.  相似文献   

Sediment-chemistry response to land-use change and pollutant loading in a hypertrophic lake, southern Sweden   总被引：3，自引：0，他引：3  

Siv Olsson  Joachim Regnéll  Anders Persson  Per Sandgren 《Journal of Paleolimnology》1997,17(3):275-294

Responses to recent land-use changes and pollutant loading in the sediment of a hypertrophic lake in southern Sweden were studied by comparison of geochemical, pollen and magnetic records with historical land-use data. A chronology was constructed for the last two centuries by correlating changes in the pollen diagram to major events in the land-use history. Sediment accumulation was low (mean c. 0.2 g cm^-2 yr^-1) prior to 1800 AD, when less than 25% of the catchment was arable land. Reorganization of the agrarian system during the 19th century increased the annually tilled area by 300%, which accelerated soil erosion and substantially increased the accumulation of allochtonous matter in the lake. Since the turn of the century 90% of the catchment has been ploughed every year. The deposition of clastic matter in the lake has, however, decreased due to a gradual rerouting of the drainage system, which has reduced the effective catchment area by c. 85%.Authigenic vivianite (Fe3(PO4)2.8H2O) is a major P phase in the preindustrial non-sulphidic sediments, which suggests that the sediments at that time served as a fairly efficient sink for P. The arable expansion, increased manuring and, eventually, the introduction of artificial fertilizers during the 19th century led to a massive influx of nutrients, which elevated primary production in the lake. Subsequent development of bottom water anoxia around 1900, in combination with an additional pollutant burden of sulphate within the lake basin, led to major alterations of the biogeochemical cycles. The most critical change in the post-1900 sediments involved the cycling of Fe and P. The linkage between the lacustrine P and Fe cycles can explain that FeS formation was paralleled by a release of P from the sedimentary pool. This supply of P to the lake basin must have supplemented the nutrient supply by modern agriculture and contributed to recent hypertrophication. The bacterial sulphate reduction also affected the generation of alkalinity which supported a significant calcite precipitation in the post-1900 sediments.S is enriched 10-fold in the post-1900 sediments compared to preindustrial values. Along with the rise in S, soot particles derived from fossil fuel combustion appear in the sediments for the first time. Therefore, Bussj¨osj¨on is thought to be a good example of how a well-buffered, highly productive lake may respond to the pollution by sulphur from acid rain.  相似文献   

3D modelling of hydrothermal alteration associated with VHMS deposits in the Kristineberg area,Skellefte district,northern Sweden     

Riia M. Chmielowski  Nils Jansson  Mac Fjellerad Persson  Pia Fagerström 《Mineralium Deposita》2016,51(1):113-130

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Total waterborne carbon export and DOC composition from ten nested subarctic peatland catchments—importance of peatland cover,groundwater influence,and inter‐annual variability of precipitation patterns     

David Olefeldt  Nigel Roulet  Reiner Giesler  Andreas Persson 《水文研究》2013,27(16):2280-2294

Waterborne carbon (C) export from terrestrial ecosystems is a potentially important flux for the net catchment C balance and links the biogeochemical C cycling of terrestrial ecosystems to their downstream aquatic ecosystems. We have monitored hydrology and stream chemistry over 3 years in ten nested catchments (0.6–15.1 km²) with variable peatland cover (0%–22%) and groundwater influence in subarctic Sweden. Total waterborne C export, including dissolved and particulate organic carbon (DOC and POC) and dissolved inorganic carbon (DIC), ranged between 2.8 and 7.3 g m^–2 year^–1, representing ~10%–30% of catchment net ecosystem exchange of CO₂. Several characteristics of catchment waterborne C export were affected by interacting effects of peatland cover and groundwater influence, including magnitude and timing, partitioning into DOC, POC, and DIC and chemical composition of the exported DOC. Waterborne C export was greater during the wetter years, equivalent to an average change in export of ~2 g m^–2 year^–1 per 100 mm of precipitation. Wetter years led to a greater relative increase in DIC export than DOC export due to an inferred relative shift in dominance from shallow organic flow pathways to groundwater sources. Indices of DOC composition (SUVA₂₅₄ and a₂₅₀/a₃₆₅) indicated that DOC aromaticity and average molecular weight increased with catchment peatland cover and decreased with increased groundwater influence. Our results provide examples on how waterborne C export and DOC composition might be affected by climate change. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献