Effect of sub-indicator weighting schemes on the spatial dependence of multidimensional phenomena     

Libório  Matheus Pereira  de Abreu  João Francisco  Ekel  Petr Iakovlevitch  Machado  Alexei Manso Correa 《Journal of Geographical Systems》2023,25(2):185-211

Journal of Geographical Systems - The weighting of sub-indicators is widely debated in the composite indicator literature. However, these weighting schemes’ effects on the composite...  相似文献   

Imprint of the Atlantic multi-decadal oscillation and Pacific decadal oscillation on southwestern US climate: past,present, and future     

Petr Chylek  Manvendra K. Dubey  Glen Lesins  Jiangnan Li  Nicolas Hengartner 《Climate Dynamics》2014,43(1-2):119-129

The surface air temperature increase in the southwestern United States was much larger during the last few decades than the increase in the global mean. While the global temperature increased by about 0.5 °C from 1975 to 2000, the southwestern US temperature increased by about 2 °C. If such an enhanced warming persisted for the next few decades, the southwestern US would suffer devastating consequences. To identify major drivers of southwestern climate change we perform a multiple-linear regression of the past 100 years of the southwestern US temperature and precipitation. We find that in the early twentieth century the warming was dominated by a positive phase of the Atlantic multi-decadal oscillation (AMO) with minor contributions from increasing solar irradiance and concentration of greenhouse gases. The late twentieth century warming was about equally influenced by increasing concentration of atmospheric greenhouse gases (GHGs) and a positive phase of the AMO. The current southwestern US drought is associated with a near maximum AMO index occurring nearly simultaneously with a minimum in the Pacific decadal oscillation (PDO) index. A similar situation occurred in mid-1950s when precipitation reached its minimum within the instrumental records. If future atmospheric concentrations of GHGs increase according to the IPCC scenarios (Solomon et al. in Climate change 2007: working group I. The Physical Science Basis, Cambridge, 996 pp, 2007), climate models project a fast rate of southwestern warming accompanied by devastating droughts (Seager et al. in Science 316:1181–1184, 2007; Williams et al. in Nat Clim Chang, 2012). However, the current climate models have not been able to predict the behavior of the AMO and PDO indices. The regression model does support the climate models (CMIP3 and CMIP5 AOGCMs) projections of a much warmer and drier southwestern US only if the AMO changes its 1,000 years cyclic behavior and instead continues to rise close to its 1975–2000 rate. If the AMO continues its quasi-cyclic behavior the US SW temperature should remain stable and the precipitation should significantly increase during the next few decades.  相似文献   

Observed spatiotemporal characteristics of drought on various time scales over the Czech Republic   总被引：4，自引：2，他引：2  

Vera Potop  Constanţa Boroneanţ  Martin Možný  Petr Štěpánek  Petr Skalák 《Theoretical and Applied Climatology》2014,115(3-4):563-581

This paper analyses the observed spatiotemporal characteristics of drought in the Czech Republic during the growing season (April to September) as quantified using the Standardised Precipitation Evapotranspiration Index (SPEI) on various time scales. The SPEI was calculated for various lags (1, 3, 6, 12, and 24 months) from monthly records of mean temperature and precipitation totals using a dense network of 184 climatological stations for the period 1961–2010. The characteristics of drought were analysed in terms of the temporal evolution of the SPEI, the frequency distribution and duration of drought at the country level, and for three regions delimited by station altitude. The driest and the wettest years during the growing season were identified. The frequency distribution of the SPEI values for seven drought category classes (in per cent) indicates that normal moisture conditions represent approximately 65 % of the total SPEI values for all time scales in all three regions, whereas moderate drought and moderate wet conditions are almost equally distributed around 10.5 %. Differences in extremely dry conditions (5 %) compared with extremely wet conditions (1.5 %) were observed with increasing SPEI time scales. The results of the non-parametric Mann–Kendall trend test applied to the SPEI series indicate prevailing negative trends (drought) at the majority of the stations. The percentage of stations displaying a significant negative trend for the 90, 95, 99, and 99.9 % confidence levels is approximately 40 %. An Empirical Orthogonal Functions (EOF) analysis was used to identify the principal patterns of variability of the SPEI during the growing season that accounted for the highest amount of statistical variance. The variance explained by the leading EOF range 66 to 56 %, whereas for EOF2 and EOF3, the value is between 7 and 11 % and between 4 and 7 %, respectively, for the SPEI is calculated for 1- to 24-month lags.  相似文献   

Empirical test of the spectral invariants theory using imaging spectroscopy data from a coniferous forest     

Petr Lukeš  Miina Rautiainen  Pauline Stenberg  Zbyněk Malenovský 《International Journal of Applied Earth Observation and Geoinformation》2011

The spectral invariants theory presents an alternative approach for modeling canopy scattering in remote sensing applications. The theory is particularly appealing in the case of coniferous forests, which typically display grouped structures and require computationally intensive calculation to account for the geometric arrangement of their canopies. However, the validity of the spectral invariants theory should be tested with empirical data sets from different vegetation types. In this paper, we evaluate a method to retrieve two canopy spectral invariants, the recollision probability and the escape factor, for a coniferous forest using imaging spectroscopy data from multiangular CHRIS PROBA and NADIR-view AISA Eagle sensors. Our results indicated that in coniferous canopies the spectral invariants theory performs well in the near infrared spectral range. In the visible range, on the other hand, the spectral invariants theory may not be useful. Secondly, our study suggested that retrieval of the escape factor could be used as a new method to describe the BRDF of a canopy.  相似文献   

Evaluation of meteorological controls of reconstructed rockfall activity in the Czech Flysch Carpathians     

Karel Šilhán  Rudolf Brázdil  Tomáš Pánek  Petr Dobrovolný  Lucie Kašičková  Radim Tolasz  Ondřej Turský  Marek Václavek 《地球表面变化过程与地形》2011,36(14):1898-1909

Rockfall is an important process in the final sculpturing of escarpments and scree slopes that originate in bedrock landslides in the Flysch Carpathians. The spatio‐temporal characteristics of rockfall activity were studied at four localities representative of old landslides in the highest part of the Czech Flysch Carpathians (Moravskoslezské Beskydy Mountains). Historical activity, chronology, and spatial context of rockfall activity were reconstructed using dendrogeomorphic techniques and rockfall rate index (RR). A total of 1132 increment cores from 283 trees growing in the rockfall transport and accumulation zones enabled the dating of 989 rockfall events. Reconstruction of a 78‐year‐long RR chronology suggests similar rockfall histories and trends at all study sites, indicating the existence of major common factors driving rockfall dynamics in the region. Temporal analysis and correlation of the RR series obtained with monthly mean temperatures, numbers of days with temperature transitions through 0 °C and monthly precipitation totals show that meteorological characteristics have evident but variable influence on rockfall activity. The most important factor is the effect of freeze–thaw cycles throughout the year, supplemented by low temperatures, especially during autumn. The influence of precipitation totals is of lesser importance. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Mineralogy and petrogenesis of a Ba–Ti–Zr-rich peralkaline dyke from Šebkovice (Czech Republic): Recognition of the most lamproitic Variscan intrusion     

Lukáš Krmíček  Jan Cempírek  Aleš Havlín  Antonín Přichystal  Stanislav Houzar  Michaela Krmíčková  Petr Gadas 《Lithos》2011,121(1-4):74-86

A peralkaline, ultrapotassic dyke found at ?ebkovice (T?ebí? district, western Moravia) is a mineralogically extreme member of a dyke swarm occurring along the south-eastern border of the Moldanubian Region of the Bohemian Massif. The dyke shows a simple zoning, with a very fine-grained marginal zone grading into a medium-grained central zone. It has a primary mineral assemblage of microcline and potassic amphiboles, with accessory apatite and altered phlogopite. The microcline exhibits an unusual red luminescence colour and pronounced substitution of Fe³⁺ for Al, with measured contents of Fe₂O₃ up to 8.5 wt.% (0.31 apfu Fe³⁺). Amphiboles have very high K (up to 0.99 apfu) and Si contents; their compositions follow an alkaline fractionation trend from potassic-richterite to potassic-magnesio-arfvedsonite, characterized by an increase of Na/K and a decrease of Ca, Mg, Fe²⁺ and Ti via heterovalent substitutions ^[B]Ca + ^[C](Mg,Fe²⁺) → ^[B]Na + ^[C]Fe³⁺ and Ti + Mg → 2Fe³⁺. The most evolved apatite is significantly enriched in SrO (up to 9.7 wt.%; 0.49 apfu Sr). The core of the dyke and late veinlets contain unique late- to post-magmatic Ba–Ti–Zr-bearing mineral assemblages of baotite, henrymeyerite, titanite, rutile, benitoite and bazirite. Anhedral baotite fills interstices distributed inhomogeneously in the dyke centre; it is locally replaced by a Ba-bearing titanite + henrymeyerite + rutile + quartz assemblage. Henrymeyerite (the second record in a lamproite) shows variable Fe/Ti ratios and represents a solid solution of the hepta- and hexatitanate components. Euhedral crystals of benitoite and bazirite are enclosed in the late-stage quartz–titanite–apatite veinlets in the fine-grained margin of the intrusion. In terms of a mineralogical–genetic classification, the ?ebkovice dyke can be considered as a new high-silica (~ 57 wt.% SiO₂) variety of lamproite (variety ?ebkovice), and represents a unique expression of post-collisional potassic magmatism on the south-eastern border of the Bohemian Massif. The peralkaline dykes from this area show mineralogical and geochemical features similar to those of silica-rich orogenic lamproites emplaced at destructive plate margins. In terms of the modern classification of lamproites, the ?ebkovice dyke is the first lamproite recognised in the Variscan orogenic belt.  相似文献   

Transposition of structures in the Neoproterozoic Kaoko Belt (NW Namibia) and their absolute timing     

Stanislav Ulrich  Ji?�� Konop��sek  Petr Je?��bek  Lucie Taj?manov�� 《International Journal of Earth Sciences》2011,100(2-3):415-429

Three structural profiles across the Coastal Terrane, the Boundary Igneous Complex and the Orogen Core have been studied in the Kaoko Belt of northwestern Namibia. The oldest known Si fabric is inherited from an older tectono-metamorphic event. It occurs in the Coastal Terrane only and the extent of its reworking increases from south to north. The S1 foliation reactivates or folds Si fabric in the Coastal Terrane and appears as an early planar fabric in granitoids of the Boundary Igneous Complex and migmatites of the Orogen Core domain. Superimposed subvertical S2 fabric corresponds to axial plane cleavage of upright close to isoclinal folds and the extent of its development also increases from south to north. Active migration of partial melt during S2 development in the Orogen Core dates the onset of this deformation at ~550?Ma. Distribution of F2 fold axes and L2 stretching lineations suggests pure shear?Cdominated deformation associated with development of N?CS trending S2 cleavage preserved in the central profile, followed by sinistral simple shear?Cdominated deformation on newly developed NW?CSE trending pervasive cleavage in the northern part of the area. Such spatial variation in the deformation record is attributed to the irregular shape of the Congo Craton indenter that is reflected by heterogeneous development of the S2 cleavage front in the Coastal Terrane and the Boundary Igneous Complex. Common orientation of L1 and L2 stretching lineations and solid-state reworking on both S1 and S2 planes suggest single event of sinistral transpression since 550?Ma with strain partitioning into domains of oblique thrusting (reactivated S1) and transcurrent sinistral shearing (S2 and S3). Such succession of deformation structures suggests that major subvertical shear zones in the Kaoko Belt do not correspond to early crustal discontinuities, but rather reflect late strain localization during cooling.  相似文献   

Seasonal variations of Zn, Cu, As and Mo in arsenic-rich stream at the Mokrsko gold deposit, Czech Republic   总被引：2，自引：2，他引：0  

Petr Drahota  Martin Mihaljevi?  Tomá? Grygar  Jan Rohovec  Zdeněk Pertold 《Environmental Earth Sciences》2011,62(2):429-441

Monthly sampling of slightly alkaline arsenic-rich stream in the Mokrsko gold deposit revealed seasonal variations in dissolved Zn, Cu, As and Mo. Concentrations of trace metal cations (Zn, Cu) increased as much as 330 and 178%, respectively, from minimum mean values at autumn to maximum mean values at spring. In contrast, concentrations of trace element oxyanions (As, Mo) revealed opposite seasonal pattern with increase to 189% (As) and 123% (Mo) during summer–autumn, indicating that in-stream biogeochemical process(es) played the main role in controlling the seasonal variations of these trace elements. The trace elements were mainly scavenged by low crystalline Mn oxyhydroxide and Fe oxyhydroxide (ferrihydrite). Results are consistent with sorption and coprecipitation processes controlling seasonal variations of dissolved Zn and Cu, while As and Mo dynamics appear linked to Mn redox reactions. The sorption processes and Mn redox processes are attributed to the changes of pH and oxic/anoxic conditions on the surface of oxyhydroxides, respectively, which are themselves controlled by the balance between photosynthesis and respiration. Under the geochemical conditions of the stream, inferred Mn redox reactions can only be explained by microbial activity.  相似文献   

The surface urban heat island in the city of Brno (Czech Republic) derived from land surface temperatures and selected reasons for its spatial variability     

Petr Dobrovolný 《Theoretical and Applied Climatology》2013,112(1-2):89-98

Thermal infrared images from Landsat satellites are used to derive land surface temperatures (LST) and to calculate the intensity of the surface urban heat island (UHI) during the summer season in and around the city of Brno (Czech Republic). Overall relief, land use structure, and the distribution of built-up areas determine LST and UHI spatial variability in the study area. Land-cover classes, amount and vigor of vegetation, and density of built-up areas are used as explanatory variables. The highest LST values typically occur in industrial and commercial areas, which contribute significantly to surface UHI intensity. The intensity of surface UHI, defined as the difference between mean LST for urban and rural areas, reached 4.2 and 6.7 °C in the two images analyzed. Analysis of two surface characteristics in terms of the amount of vegetation cover, represented by normalized difference vegetation index, demonstrates the predominance of LST variability (56–67 % of explained variance) over the degree of urbanization as represented by density of buildings (37–40 % of LST variance).  相似文献   

Structure and stationarity of quasi-perpendicular shocks: Numerical simulations     

Petr Hellinger 《Planetary and Space Science》2003,51(11):649-657

This paper presents an overview of numerical simulation studies of fast collisionless shocks and compares these simulation results with observations of the Earth's bow shock and theoretical works. Especially, we review the structure and stationarity of the supercritical quasi-perpendicular shocks. In situ observations indicate that these shocks are generally quasi-stationary whereas full particle simulations as well as hybrid simulations often present a strong nonstationary behavior, a shock self-reformation. The simulation results, along with theoretical and observational works, suggest that the classical models of the quasi-stationary structure generated by reflected protons or by dispersive whistlers are not generally applicable for the supercritical quasi-perpendicular shocks and other phenomena are to be included into the model to ensure the observed quasi-stationarity: The role of a small scale turbulence and shock ripples is investigated. The downstream turbulence and the electron dynamics in the quasi-perpendicular shocks are also discussed.  相似文献