Miracle-dz/UniFAR-FTUs huggingface dataset:
Evolution of the petrophysical properties of two types of Alsatian sandstone subjected to simulated freeze-thaw conditions

Abstract Stone monuments in Alsace (eastern France) are built with two types of Buntsandstein sandstone (Lower Triassic). Their different pore structures cause them to have mixed petrophysical properties and occasion a different response to frost. To understand these differences, frost simulation experiments have been carried out on samples of both stones. Four series of 30 freeze-thaw cycles were reproduced on samples maintained at constant saturation, either total or partial, without drying or rewetting. Macroscopic and microscopic change due to frost was observed by scanning electronic microscope, by mercury porosimetry and P-wave velocity measurements. Change of tensile strength and capillary kinetics was also assessed before and after each series. Results demonstrate that frost action increases heterogeneity of the porous network particularly in the initially more heterogeneous sandstone. When saturation is partial, no macroscopic cracking occurs and capillary absorption decreases. When saturation is total, macroscopic cracking prevails over microscopic heterogeneity and capillary absorption increases. Control tests have also been carried out to evaluate the effects induced by absorption-drying cycles without frost, and dilation experiments have been added to assess freeze-thaw action on dilation of sandstones. The results of all these experiments demonstrate that frost plays a less decisive part in the weathering mechanisms of stones than wetting-drying.
Public Transport in Dar-es-Salaam, Tanzania.

The study which was conducted from January 2003 to December 2004 was to yield a specific knowledge about the technical and institutional problems, challenges and opportunities in planning for sustainable urban transportation. Before reaching this stage, it was necessary to get a clear picture the problem, and this showed that the performance of public transportation in Dar-es-Salaam in terms of social, economic and environmental aspects was distressing. The existing public transport system is characterized by: i) congestion and delays; ii) excessive gaseous emissions from vehicles; iii) increasing road accidents; iv) inadequate road infrastructure; v) poor vehicle standard; vi) poor infrastructure for non-motorised modes; vii) low bus fares insufficient to cover operating costs and (viii) uncomfortable and unsafe customer services. The report examines the actual problems and conditions of traveling in Dar-es-Salaam from interviews with different groups and classes of people in the neighborhoods which included women, pupils, parents, older persons and disabled people. The examination included the question of vehicular air pollution and the historical and dynamic changes of public transportation in terms of quality since when it was introduced in Dar-es-Salaam in 1949. The report surveys strategic approaches applied and examines various mechanisms of interventions to solve the problems by stakeholders in the public transportation sector, namely institutions, agencies and private operators. (Less)
On the Steadiness of Separating Meandering Currents

The existence of inertial steady currents that separate from a coast and meander afterward is investigated. By integrating the zonal momentum equation over a suitable area, it is shown that retroflecting currents cannot be steady in a reduced gravity or in a barotropic model of the ocean. Even friction cannot negate this conclusion. Previous literature on this subject, notably the discrepancy between several articles by Nof and Pichevin on the unsteadiness of retroflecting currents and steady solutions presented in other papers, is critically discussed. For more general separating current systems, a local analysis of the zonal momentum balance shows that given a coastal current with a specific zonal momentum structure, an inertial, steady, separating current is unlikely, and the only analytical solution provided in the literature is shown to be inconsistent. In a basin-wide view of these separating current systems, a scaling analysis reveals that steady separation is impossible when the interior flow is nondissipative (e.g., linear Sverdrup-like). These findings point to the possibility that a large part of the variability in the world’s oceans is due to the separation process rather than to instability of a free jet.
Estimating water balance components of tropical wetland lakes in the Pantanal dry season, Brazil

Abstract Water balance studies with stable water isotopes have rarely been conducted in remote and tropical wetland areas. As such, little is known regarding the water balance and groundwater–surface water interaction in the Pantanal, one of the largest and most pristine wetlands in the world. We applied MINA TrêS, a water balance model utilizing stable water isotopes (δ18O, δ2H) and chloride (Cl-) to assess the dry-season hydrological processes controlling groundwater–surface water interactions and the water balance of six floodplain lakes in the northern Pantanal, Brazil. Qualitatively, all lakes exhibited similarity in hydrological controls. Quantitatively, they differed significantly due to morphological differences in controlling groundwater inflow and lake volume. Our approach is readily transferable to other remote and tropical wetland systems with minimal data input requirements, which is useful in regions with sparse hydrometric monitoring. Editor Z.W. Kundzewicz
Investigation of field-installation effects of horizontal twin-jet grouting in Shanghai soft soil deposits

This paper presents a case study of an investigation into the responses of the surrounding ground to the horizontal twin-jet grouting method (HTJGM) in soft soil deposits of Shanghai. During the field test, the variation of pore-water pressure, lateral earth pressure, lateral displacements of the subsurface soils, and ground surface heave induced by the installation of five horizontal jet-grouted columns were monitored. The monitoring results indicate that the excess pore-water pressure reached 4 to 6 times the undrained shear strength of the soils, while maximum lateral displacements and ground surface heave were up to 80 and 17 mm, respectively. The influence range due to the installation of jet-grouted columns was between 15 and 20 times the nominal column radius. The development of prediction methods for lateral displacements and ground surface heave induced by the HTJGM installation process are presented and discussed. Results from the investigation suggest that the proposed prediction methods can be.
The Politics of Heritage Tourism in China: A View from Lijiang

1. Rethinking tourism politics 2. The cultural politics of tourism: exploring the complexity of hegemony 3. Locating Lijiang: connections and process 4. Producing heritage: Lijiang's immersion into global tourism 5. Consuming heritage: tourists' expectations and influence on Lijiang 7. Local agency in heritage tourism 8. Conclusion: cultural politics of heritage tourism and beyond
Lightning‐generated NOx seen by the Ozone Monitoring Instrument during NASA's Tropical Composition, Cloud and Climate Coupling Experiment (TC4)

[1] We present case studies identifying lightning-generated upper tropospheric NOx (LNOx) observed during NASA's Tropical Composition, Cloud and Climate Coupling Experiment (TC4) in July and August 2007. In the campaign, DC-8 aircraft missions, flown from Costa Rica, recorded in situ NO2 profiles near active storms and in relatively quiet areas. We combine these TC4 DC-8 data with satellite data from the Ozone Monitoring Instrument (OMI) to estimate the lightning-generated NO2 (LNO2), above background levels, in the observed OMI NO2 fields. We employ improved off-line processing techniques to customize the OMI retrieval for LNO2. Information on lightning flashes (primarily cloud-to-ground) observed by the Costa Rica Lightning Detection Network operated by the Instituto Costarricense de Electricidad and the World Wide Lightning Location Network were examined over storms upwind of regions where OMI indicates enhanced LNO2. These flash data are compared with Tropical Rainfall Measuring Mission/Lightning Imaging Sensor satellite data to estimate total flashes. Finally, using [NOx]/[NO2] ratios from NASA's Global Modeling Initiative model, we estimate LNOx production per flash for four cases and obtain rates of ∼100-250 mol/flash. These are consistent with rates derived from previous studies of tropical and subtropical storms and below those from modeling of observed midlatitude storms. In our study, environments with stronger anvil-level winds were associated with higher production rates. LIS flash footprint data for one of the low-LNOx production cases with weak upper tropospheric winds suggest below-average flash lengths for this storm. LNOx enhancements over background determined from the OMI data were in less than, but roughly proportional to, aircraft estimates.
A reconstruction of Moorhead and Emerson Phase environments along the eastern margin of glacial Lake Agassiz, Rainy River basin, northwestern Ontario

Mapping of Quaternary geology in the Rainy River lowland, northwestern Ontario resulted in discovery of several fossil-bearing localities. Organic remains are associated with both the Moorhead and Emerson phases of glacial Lake Agassiz. Wood samples recovered from Moorhead Phase deposits have radiocarbon ages ranging between 10.8 and 9.9 ka BP. The wood is detrital and cannot be used to date the beginning of the low-water phase. Nearshore, deltaic, alluvial, peatland, open-water wetland, and upland soil environments are represented in the Moorhead Phase sediment records. Emerson Phase transgressive deposits overlie Moorhead Phase sediments and erosional surfaces. Wood samples recovered from flotsam layers in Emerson Phase nearshore deposits have yielded radiocarbon ages rang- ing between 10.5 and 9.5 ka BP. Stratigraphic and sedimentologic evidence suggests that the transgression began ap- proximately 9.9 ka BP. Pollen, plant macrofossil, insect, and mollusc assemblages have been affected by long-distance transport, sorting, and reworking by fluvial and nearshore processes. They represent a wide spectrum of terrestrial and aquatic habitats indiscriminantly brought together during high-water periods. The Moorhead and Emerson phase assem- blages indicate conditions similar to those in the region today, but there is a distinct component whose modern range is much farther north and west of the study region. In this respect, the assemblages are similar to the mixed communities described from other late-glacial sites of the mid-continent.
Atmospheric circulation and surface temperature in Europe from the 18th century to 1995

The relationship between surface atmospheric circulation and temperature in Europe from the 1770s to 1995 is examined using correlation analysis. The atmospheric circulation is represented by six indices: the three leading principal components (PCs) of an empirical orthogonal function (EOF) analysis of 20 European pressure series from 1822 to 1995, which represent the central tendency of European pressure (EOF 1), a zonal circulation pattern (EOF 2) and a meridional pattern (EOF 3), a North Atlantic zonal index constructed from Gibraltar and Reykjavik pressure series for 1821–1995; a Western European zonal index constructed from Madrid, Barcelona, Lund and Trondheim for 1786–1995; and an index constructed from Paris and London, 1774–1995. Eight long temperature series from northwestern and central Europe were correlated with these circulation indices. European temperatures in general had the highest correlations with the zonal circulation indices in winter, with almost 70% of the variability in the temperature records explained by variations in the zonal index. The correlation coefficients between PC 3 (representing meridional circulation) and temperatures were highest in spring and autumn, particularly for Scandinavia. Running correlation series calculated over 25‐year windows reveal significant non‐stationarities in the relationship between surface temperature and atmospheric circulation on decadal time scales, suggesting caution must be used in extrapolating current relationships between circulation and temperature for future climate predictions based on downscaling or past palaeoclimatic reconstructions. Copyright © 2001 Royal Meteorological Society
Light-Absorbing Material Extracted From Cloud Droplets and Its Effect on Cloud Albedo

Using the counterflow virtual impactor, a new instrument for sampling cloud droplets, measurable levels of light-absorbing material were found to exist inside droplets in stratocumulus clouds off the coast of southern California. Eighty percent of the samples of droplet residue material had light absorption coefficients ranging from 6 to 20 × 10−8 m−1 (where m−1 means per meter of distance in the cloud, not in the cloud droplet nor in the dried bulk aerosol material). Calculated soot concentrations were between 23 and 79 ng soot g−1 of cloud water. These values are in general agreement with aerosol, rainwater, and snow measurements from other experiments and suggest that the coastal clouds were influenced by continental air. Aircraft measurements determined that the sampled clouds had average liquid water contents of 0.24–0.31 g m−3, effective droplet radii of 5.0–7.8 μm, and optical thicknesses of 14–28. Radiative transfer calculations indicate that even at the most sensitive wavelength, the maximum amount of light-absorbing material from cloud air and inside cloud droplets in this experiment would not significantly alter the albedos of the clouds that were measured. The same amount could possibly affect the albedo of much thicker clouds or of snowpacks (which have relatively large particles and optical thicknesses).
Transport pathways of Sahara dust over Athens, Greece as detected by MODIS and TOMS

This study analyses the Saharan dust (SD) events over Athens during 2000–2005 using daily Moderate Resolution Imaging Spectroradiometer (MODIS) and Total Ozone Mapping Spectrometer (TOMS) satellite data. The dust events were identified using the MODIS daily observations over Greece and the dates with detectable dust plumes were collected. The aerosol optical depth (AOD550) and fine-mode (FM) values from Terra-MODIS and Aerosol Index (AI) values from TOMS were obtained over Athens for the dusty days focusing on analysing the seasonality, intensity, transport pathways and mechanisms of dust. Seventy-nine dusty days were identified corresponding to SD events with duration from 1 to 4 consecutive days; the majority of SD events occur in April–May and July, with less during winter. The dust frequency presents large seasonal and intra-annual variation, with a maximum of 20 dust events in 2002 and a minimum of 7 in 2003. The use of TOMS-AI seems to be adequate for the characterization of dust over Athens despite the fact that 35% of the dusty days do not correspond to high AI values. The dust events are more intense during spring, mostly associated with dust transport from near surface to mid troposphere (vertical transport mechanism), while dust events detected only within the boundary layer have the lowest AOD values. On the other hand, the dust events in summer are of larger duration due to stable weather conditions and absence of precipitation and transportation at elevated heights.
Sedimentation from turbulent jets and plumes

Theoretical models are developed for the sedimentation from the margins of a particle-laden, axisymmetric, turbulent, buoyant plume, in a still environment and for an axisymmetric turbulent momentum jet. The models assume that the mass of each individual size fraction of sediment carried in a parcel of fluid decreases exponentially with time. For relatively coarse particles, the fallout models predict that the sediment deposition beyond a distance r on the ground expressed in log units should decay linearly with distance away from the vent for the momentum jet and should decrease with r1/3 for the buoyant plume. The exponential decay constant J is proportional to the terminal fall velocity Vt of the particles in both cases and inversely proportional to the square root of the initial momentum flux M0 for the jet fallout (Jj ∝ VtMo−1/2) and to the third power of the initial buoyancy flux Fo for the plume fallout (Jp ∝ VtFo−1/3). Smaller particles are affected by reentrainment caused by the turbulent eddies sweeping ambient fluid back into the plume or jet and thus reincorporating some particles that were released from the flow at greater heights. This is taken into account by introducing a reentrainment coefficient, ϕ, into the theoretical models with the assumption that the coefficient has a constant value for a plume of given strength. In new experiments, fallout occurs from the margins of particle-laden, fresh water, buoyant jets, and plumes in a tank of salty water, and sedimentation is measured on the tank floor. Two experiments were weakly affected by reentrainment and show excellent agreement with the simple theory. For smaller particles and increasingly buoyant plumes and strong jets, particle reentrainment is important. The experimental data are fitted by the new reentrainment theory, confirming that values of the reentrainment coefficient are approximately constant for a given flow. A settling number, β, is defined as the ratio of the characteristic velocity of the jet or plume to the particle settling velocity. For β ≥ 1, reentrainment seems to reach an equilibrium state for which the reentrainment coefficient is a constant of value 0.1 for jets and 0.4 for plumes, irrespective of flow strength or particle size. The plume experiments indicate that the value of the reentrainment coefficient is strongly dependent on plume strength and particle size for β slightly less than 1. The general principles of sedimentation from turbulent plumes and jets are applied to the fallout of pumice from volcanic eruption columns and of metalliferous particles from black smokers on the ocean floor. For volcanic eruptions, the results provide an explanation for the near vent overthickening of tephra fall deposits and imply that lithic and pumice fragments from small lapilli up to at least 1 m diameter blocks are efficiently reentrained into eruption columns. The size of particles reentrained in hydrothermal plumes is predicted to vary from less than 100 μm in weakly buoyant plumes up to over 1000 μm in megaplumes.
Decadal changes in the relationship between the tropical Pacific and the North Pacific

[1] It has been recognized that the tropical Pacific sea surface temperature (SST) anomaly associated with the El Nino/Southern Oscillation (ENSO) is closely tied to large-scale atmospheric anomalies in the extra-tropical region. Based on observational data, this connection appears to have changed significantly since 1999. This study examines the characteristics of this connection during two sub-periods (1980–1998 and 1999–2010) using cyclostationary empirical orthogonal function (CSEOF) analysis. We found that the atmospheric anomalies induced by the ENSO alter the SST over the North Pacific through surface heat flux change during the earlier period of 1980–1998. During the later period, in contrast, ENSO-related atmospheric anomalies feature the North Pacific oscillation (NPO) pattern during winter, which is characterized by a southward shift of the atmospheric center of action from its climatological position. The NPO-related atmospheric anomalies extend to the subtropical Pacific; this extension potentially links midlatitude and tropical Pacific variability through air-sea interactions. The physical change appears to alter the El Nino characteristics into that of the Central Pacific El Nino through the wind-SST coupling mechanism. This process may be related to the recent change in which the Central Pacific El Nino occurs more frequently than the conventional Eastern Pacific El Nino. Detailed descriptions of the physical changes between the tropical Pacific and the North Pacific are presented in this study along with the possible implications of this change.
On the formation of eruption columns following explosive mixing of magma and surface‐water

When magma vents into the sea or a crater lake, the ensuing magma-water interaction can affect the style of eruption dramatically. If the mass of surface water incorporated into the erupting material is small, ( 108 kg/s, the height progressively decreases with surface water content. This occurs when the magma and surface water begin to constitute a significant fraction of the mass at the top of the column, so that an increasing fraction of the initial magmatic thermal energy is converted to the surface water rather than the entrained air. The transitions in eruption style which result from changes in the mass of surface water mixing with the magma may account for observations of both buoyant plumes and wet surge during the eruptions of Taal in 1965 and Miyake-jima in 1983 and for the changes in the eruptive activity at Surtsey in 1963–1964 as the access of seawater to the vent became more restricted. We also present calculations which suggest that the accretionary lapilli, which are often found in wet flow deposits, may result from condensation of vapor in both the cold, wet collapsing fountains and in the flows themselves.
Palaeotectonic cross-sections through the Mid-Polish Trough

The Late Permian and Mesozoic evolution of the Mid-Polish Trough is analysed using a set of palaeotectonic cross-sections which are constrained by regional integrated depth-converted reflection seismic profiles. Results support the concept that the central and NW part of the Mid-Polish Trough can be subdivided into a Pomeranian and a Kuiavian segment. The Pomeranian segment is characterised by lower subsidence and a shallower depth to the base of the Zechstein (3500-4000 m) as compared with the Kuiavian segment. The Pomeranian basin was characterised by a nearly symmetrical structure and a single depocentre. In Kujawy, the basin displays a more complex structure with several local depocentres. In the Pomeranian segment, salt structures are poorly developed (salt pillows). These formed relatively late: during the latest Cretaceous and Early Paleocene. In the Kuiavian segment, salt structures include also salt diapirs which began to form at the end of the Muschelkalk, and were active later throughout Mesozoic times, as evidenced by lateral facies and thickness changes. During end Cretaceous and Paleocene basin inversion, the base of the Zechstein was uplifted by 3000-4000 m in the Kuiavian segment and by 2000-3000 m in the Pomeranian segment. The transition zone between the Pomeranian and Kuiavian segments, located in the area between Pila and Toru, displays mixed features in its structure and geological evolution. Subsidence of the Mid-Polish Trough was controlled by multiple extensional pulses during which pre-existing crustal-scale faults were reactivated. Similarly, inversion of the Mid-Polish Trough involved reactivation of crustal faults. Segmentation of the Mid-Polish Trough can be related to factors including differences in its basement composition.