Effect of asymmetrical street canyons on pedestrian thermal comfort in warm-humid climate of Cuba

Walkability and livability in cities can be enhanced by creating comfortable environments in the streets. The profile of an urban street canyon has a substantial impact on outdoor thermal conditions at pedestrian level. This paper deals with the effect of asymmetrical street canyon profiles, common in the historical centre of Camagüey, Cuba, on outdoor thermal comfort. Temporal-spatial analyses are conducted using the Heliodon2 and the RayMan model, which enable the generation of accurate predictions about solar radiation and thermal conditions of urban spaces, respectively. On these models, urban settings are represented by asymmetrical street canyons with five different height-to-width ratios and four street axis orientations (N-S, NE-SW, E-W, SE-NW). Results are evaluated for daytime hours across the street canyon, by means of the physiologically equivalent temperature (PET index) which allows the evaluation of the bioclimatic conditions of outdoor environments. Our findings revealed that high profiles (façades) located on the east-facing side of N-S streets, on the southeast-facing side of NE-SW streets, on the south-facing side of E-W street, and on the southwest-facing side of SE-NW streets, are recommended to reduce the total number of hours under thermal stress. E-W street canyons are the most thermally stressed ones, with extreme PET values around 36 °C. Deviating from this orientation ameliorates the heat stress with reductions of up to 4 h in summer. For all analysed E-W orientations, only about one fifth of the street can be comfortable, especially for high aspect ratios (H/W > 3). Optimal subzones in the street are next to the north side of the E-W street, northwest side of the NE-SW street, and southwest side of the SE-NW street. Besides, when the highest profile is located on the east side of N-S streets, then the subzone next to the east-facing façade is recommendable for pedestrians. The proposed urban guidelines enable urban planners to create and renovate urban spaces which are more efficient in diminishing pedestrian thermal stress.     

Morphometric and geological conditions for sediment accumulation in the Udava River,Outer Carpathians,Slovakia

The accumulation of sediment in river channels is a phenomenon that is not only influenced by the channel morphology, but also by the physical and geographical characteristics and the endogenous and exogenous processes taking place in the catchment. This paper presents an analysis of the impact the changes in lithological conditions have on the morphological and morphometric parameters of the Udava River channel and their relation to the channel accumulation forms representative of the river’s longitudinal profile as well as of its planform. Results document when accumulation forms occur and what is their spatial distribution within the longitudinal and cross-sectional river profiles. More resistant structures created sections with a lower degree of sedimentation, while in depression segments the degree of sedimentation was higher. With the increase in longitudinal slope, the impact of channel width on the average channel bar size increased. Also a difference in the accumulation was observed between the left and right bank which could be possibly explained by the impact of Coriolis force.     

Ozone structure over the equatorial Andes from balloon-borne observations and zonal connection with two tropical sea level sites

In this paper we present first-time measurements of ozone profiles from a high altitude station in Quito, Ecuador (0.19°S, 78.4°W, and 2391 masl) taken from June 2014 to September 2015. We interpret ozone observations in the troposphere, tropopause, and stratosphere through a zonal comparison with data from stations in the Atlantic and Pacific (Natal and San Cristobal from the SHADOZ network). Tropospheric ozone concentrations above the Andes are lower than ozone over San Cristobal and Natal for similar time periods. Ozone variability and pollution layers are also reduced in the troposphere above the Andes. We explain these differences in terms of reduced contributions from the boundary layer and from horizontal transport. In the tropical tropopause layer, ozone is well-mixed up to near the cold point tropopause level. In this regard, our profiles do not show constraints to deep mixing above 14 km, as has been consistently observed at other tropical stations. Total column ozone and stratospheric column ozone are comparable among the three sites. However, the contribution of tropospheric column ozone to total column ozone is significantly lower above the Andes. Our comparisons provide a connection between observations from tropical stations in equatorial South America separated by the wide continental mass. Identified differences in ozone throughout the atmospheric column demonstrate the global benefit of having an ozone sounding station at the equatorial Andes in support of global monitoring networks.     

Trends in the characteristics of the annual and semiannual variations observed in the radio wave absorption in the lower ionosphere

The continuous increase in concentration of greenhouse gases in the atmosphere is expected to cool higher levels of the atmosphere. There is some direct and indirect experimental evidence of long-term trends in temperature and other parameters in the mesosphere and lower thermosphere (MLT). Here we look for long-term trends in the annual and semiannual variations of the radio wave absorption in the lower ionosphere, which corresponds to the MLT region heights. Data from central and southeastern Europe are used. A consistent tendency to a positive trend in the amplitude of the semiannual wave appears to be observed. The reality of a similar tendency in the amplitude of the annual wave is questionable in the sense that the trend in the amplitude of the annual wave is probably induced by the trend in the yearly average values of absorption. The phases of both the annual and semiannual waves display a forward tendency, i.e. shift to an earlier time in the year. A tentative interpretation of these results in terms of changes of the seasonal variation of temperature and wind at MLT heights does not contradict the trends observed in those parameters.     

Can we predict the future food production? A sensitivity analysis

An attempt is made to assess the sensitivity of food production to various aspects of global change and environmental degradation during the next few decades. As a tool for this study a spreadsheet accounting system for food demand and supply is used. Taking into account the uncertainties of the various influencing factors, such as new technologies, improved management, increased fertilizer use, climatic change, expansion of irrigation, soil degradation and loss of agricultural land, the study indicates that one cannot say with any certainty whether or not food supply will meet expected demand in 2025, especially in Less Developed Countries. Bringing into use 10% of available potential cropland will make little difference.     

Origin of peraluminous granites and granodiorites, Iberian massif, Spain: an experimental test of granite petrogenesis

The discrimination between potential source materials involved in the genesis of Iberian granites and granodiorites, as well as the role of mantle-crust interactions, are examined using constraints imposed by melting experiments, melting-assimilation experiments and Sr-Nd isotope systematics. The Sr-Nd isotope relationships indicate the existence of different genetic trends in which juvenile mantle materials are involved by different mechanisms: (1) a source trend, traced by a particular evolution of the pre-Hercynian basement and indicating mantle participation at the time of sedimentation; (2) a set of magmatic trends traced by gabbro-tonalite-enclave-granodiorite associations, implying the incorporation of new mantle material at the time of granite generation. These relationships strongly support a pure crustal origin for the peraluminous leucogranites, derived from partial melting of crustal protoliths, and a hybrid origin for the peraluminous granodiorites. These granodiorites are the most abundant granitic rocks of the Central Iberian zone (CIZ) of the Iberian massif, implying that processes of hybridisation by assimilation and/or magma mixing played an important role in granitoid production during the Hercynian orogeny. These hypotheses have been tested by means of melting and assimilation experiments. Melting experiments in the range 800–900 °C and at pressures of 3, 6, 10 and 15 kbar indicate that: (1) several potential source materials such as Bt-Ms gneisses and metagreywackes are suitable for the production of peraluminous leucogranite melts; (2) the melt compositions are always leucogranitic, regardless of pressure; (3) pressure exerts a strong influence on the fertility of the source: experiments at 3 kbar produce more than 20 vol% of melt, compared with less than 5 vol% of melt produced at 10 and 15 kbar and at the same temperature. The melting-assimilation experiments carried out at 1000 °C and 4, 7 and 10 kbar and using a proportion of 50% gabbro and 50% gneiss give high melt proportions (more than 50 vol.%) and noritic residues. These melts have the composition of leucogranodiorites, and overlap with part of the compositional range of peraluminous granodiorites of the Iberian massif. The generation of more mafic granodiorites may be explained by the incorporation of some residual orthopyroxene to the granodiorite magmas. The low solubility of Fe + Mg prevents the generation of granodiorite melts with more than 3 wt% of MgO + FeO at all crustal pressures. The large volumes of peraluminous, hybrid granodiorites, produced by assimilation of crustal rocks by mantle magmas, imply that an important episode of crustal growth took place during the Late-Palaeozoic Hercynian orogeny in the Iberian massif. Received: 30 June 1998 / Accepted: 27 November 1998     

The BanskáŠtiavnica ore district: relationship between metallogenetic processes and the geological evolution of a stratovolcano

The Banská?tiavnica ore district is in the central zone of the largest stratovolcano in the Central Slovakia Neogene Volcanic Field, which is situated at the inner side of the Carpathian arc over the Hercynian basement with the Late Paleozoic and Mesozoic sedimentary cover. Volcanic rocks of the High-K orogenic suite are of the Badenian through Pannonian age (16.5–8.5?Ma). Their petrogenesis is closely related to subduction of flysch belt oceanic basement underneath the advancing Carpathian arc and to back-arc extension processes. The stratovolcano includes a large caldera 20?km in diameter and a late-stage resurgent horst in its centre, exposing a basement and extensive subvolcanic intrusive complex. The following stages have been recognized in the evolution of the stratovolcano: (1)?formation of a large pyroxene/hornblende-pyroxene andesite stratovolcano; (2)?denudation, emplacement of a diorite intrusion; (3) emplacement of a large granodiorite bell-jar pluton within the basement; (4) emplacement of granodiorite/quartz-diorite porphyry stocks and dyke clusters around the pluton; (5) caldera subsidence and its filling by biotite-hornblende andesite volcanics, emplacement of quartz-diorite porphyry sills and dykes at the subvolcanic level; (6)?renewed activity of andesites from dispersed centres on slopes of the volcano; (7) uplift of a resurgent horst accompanied by rhyolite volcanics and granite porphyry dykes. The following types of ore deposits (mineralizations) have been identified in the Banská?tiavnica ore district: 1. Quartz-pyrophyllite-pyrite high-sulphidation system at ?obov, related to the diorite intrusion. 2. Magnetite skarn deposits and occurrences?at contacts of the granodiorite pluton with Mesozoic carbonate rocks. Magnetite ores occur as lenses in the calcic skarns. 3.?Stockwork/disseminated base metal deposit along an irregular network of fractures in apical parts of the granodiorite pluton and in remnants of basement rocks. Mineral paragenesis is simple, with leading sphalerite and galena and minor chalcopyrite and pyrite. In overlying andesites the mineralization is accompanied by metasomatic quartzites and argillites with pyrophyllite, kaolinite, illite and pyrite. 4. Porphyry/skarn copper deposits and occurrences related to granodiorite/quartz-diorite porphyry dyke clusters and stocks around the granodiorite intrusion. The mineralized zone is represented by accumulations of chalcopyrite in exo- and endo-skarns, usually of the magnesian type affected by serpentinization. Besides chalcopyrite, pyrhotite, minor bornite, chalcosite, tennantite and magnetite, rare molybdenite and gold are present. The alteration pattern around productive intrusions includes an external zone of propylitization, a zone of argillitic alteration (kaolinite – illite – pyrite) and an internal zone of phyllic alteration (quartz – sericite – pyrite). Biotitization is rare and limited to porphyry intrusions. 5. Intrusion related “mesothermal” gold deposit in an andesitic environment just above the granodiorite intrusion. Gold of high fineness with base metal mineralization is contained in brecciated and/or banded quartz veins of subhorizontal orientation, parallel to the surface of granodiorite pluton. At least the first phase of mineralization is older than quartz-diorite porphyry sills, which separate granodiorite and blocks of mineralized andesite. 6. Hot spring type advanced argillic systems in the caldera filling. Silicites and opalites accompanied by kaolinite, alunite and pyrite grade downward into smectite dominated argillites. 7. Vein type epithermal precious/base metal deposits and occurrences as a result of the long lasting interaction among structural evolution of the resurgent horst and evolving hydrothermal system, extensive intrusive complex and deep seated siliceous magma chamber serving as heat and magmatic fluid source. Three types of epithermal veins occur in a zonal arrangement: (a) base metal veins ± Au with transition to Cu?±?Bi mineralization at depth in the east/central part of the horst, (b)?Ag – Au veins with minor base metal mineralization and (c) Au – Ag veins located at marginal faults of the horst. Isotopic composition of oxygen and hydrogen in hydrothermal fluids indicate mixing of magmatic and meteoric component (with generally increasing proportion of meteoric component towards younger mineralization periods?). Veins are accompanied by zones of silicification, adularization and sericitization, indicating a low sulphidation environment. 8.?Replacement base metal mineralization of a limited extent in the Mesozoic carbonate rocks next to sulphide rich epithermal base metal veins.     

Conditional heavy-tail behavior with applications to precipitation and river flow extremes

This article deals with the right-tail behavior of a response distribution \(F_Y\) conditional on a regressor vector \({\mathbf {X}}={\mathbf {x}}\) restricted to the heavy-tailed case of Pareto-type conditional distributions \(F_Y(y|\ {\mathbf {x}})=P(Y\le y|\ {\mathbf {X}}={\mathbf {x}})\), with heaviness of the right tail characterized by the conditional extreme value index \(\gamma ({\mathbf {x}})>0\). We particularly focus on testing the hypothesis \({\mathscr {H}}_{0,tail}:\ \gamma ({\mathbf {x}})=\gamma _0\) of constant tail behavior for some \(\gamma _0>0\) and all possible \({\mathbf {x}}\). When considering \({\mathbf {x}}\) as a time index, the term trend analysis is commonly used. In the recent past several such trend analyses in extreme value data have been published, mostly focusing on time-varying modeling of location or scale parameters of the response distribution. In many such environmental studies a simple test against trend based on Kendall’s tau statistic is applied. This test is powerful when the center of the conditional distribution \(F_Y(y|{\mathbf {x}})\) changes monotonically in \({\mathbf {x}}\), for instance, in a simple location model \(\mu ({\mathbf {x}})=\mu _0+x\cdot \mu _1\), \({\mathbf {x}}=(1,x)'\), but the test is rather insensitive against monotonic tail behavior, say, \(\gamma ({\mathbf {x}})=\eta _0+x\cdot \eta _1\). This has to be considered, since for many environmental applications the main interest is on the tail rather than the center of a distribution. Our work is motivated by this problem and it is our goal to demonstrate the opportunities and the limits of detecting and estimating non-constant conditional heavy-tail behavior with regard to applications from hydrology. We present and compare four different procedures by simulations and illustrate our findings on real data from hydrology: weekly maxima of hourly precipitation from France and monthly maximal river flows from Germany.     

Spectral density regression for bivariate extremes

We introduce a density regression model for the spectral density of a bivariate extreme value distribution, that allows us to assess how extremal dependence can change over a covariate. Inference is performed through a double kernel estimator, which can be seen as an extension of the Nadaraya–Watson estimator where the usual scalar responses are replaced by mean constrained densities on the unit interval. Numerical experiments with the methods illustrate their resilience in a variety of contexts of practical interest. An extreme temperature dataset is used to illustrate our methods.