Miracle-dz/UniFAR-FTUs huggingface dataset:
Ozone production from Canadian wildfires during June and July of 1995

[1] During the summer of 1995, especially between June and mid July, extensive wildfires occurred throughout Canada, primarily north of 55°N latitude. A previous report used aircraft and surface observations and tracer simulations to show these fires strongly influenced CO concentrations as far south as 35°N in the central and eastern United States [Wotawa and Trainer, 2000]. This study extends those results by incorporating wildfire emissions estimates for CO, NOx, and nonmethane hydrocarbons into a three-dimensional photochemical transport model specifically designed to simulate ozone photochemistry in the continental United States. The results of the model are compared to observations from four measurement platforms deployed during the time period of interest: National Oceanic and Atmospheric Administration WP-3 aircraft observations collected during the 1995 Southern Oxidants Study (SOS-95) field campaign; 12 eastern U.S. surface stations that measured ozone, CO, and NOy; rural ozone measurements from the Aerometric Information Retrieval System network collected by the U.S. Environmental Protection Agency; and daily ozonesondes obtained near Nashville, Tennessee, during SOS-95. Model performance, as determined by correlation and bias with observations from these four platforms, is significantly improved for both O3 and CO when the Canadian fires are considered. Both observations and model results show enhanced O3 from air transported from the Northwest Territory. The model results imply that during the period of strongest fire influence 10 to 30 ppbv enhancement of O3 throughout a large region of the central and eastern United States was due to these fires. Modeled O3 increases are sensitive to the NOx/CO emission ratio assumed for the fires, which is highly uncertain and variable. A molar NOx/CO ratio of 0.007 yields model comparisons that are most consistent for O3 and ΔO3/ΔCO observations within aged fire plumes during SOS-95, and is also consistent with previously observed NOx/CO ratios from boreal fires. For this NOx/CO emission ratio, and considering the entire eastern United States, most of the O3 increase is associated with the NOx emitted directly by the fires and the photochemical O3 formation that occurs before the plumes actually reach the United States. However, the in situ oxidation of CO from the Canadian fires with NOx emitted locally leads to significantly higher O3 increases for high-NOx-emitting regions that are limited by hydrocarbon availability. Thus O3 in urban areas, or any other region modified by nearby NOx sources, is more sensitive to long-range fires compared to less populated or polluted regions.
Rheology of subliquidus magmas: 1. Picritic compositions

The relationship between the rheology and phase equilibria of a picritic basalt from Kilauea Iki has been investigated at 1 atm along the QFM buffer. Between 1270° and 1180°C olivine and minor spinel are the only liquidus phases, and the melt volume decreases from 85 to 74 vol %. At the ol-sp-pc-cpx cotectic, melt is consumed more rapidly dropping to 47 vol % at 1139°C. The rheology of the magma is non-Newtonian, is characterized by time-dependent, pseudoplastic behavior, and is consistent with power law flow or Bingham pseudoplastic behavior. Non-Newtonian effects are most apparent when the crystal volume is greater than 25% and the shear rate is increasing. Once stirred, the magma approaches Newtonian rheology with decreasing shear rate. At 1170°C (approximately 25% suspended crystals) the apparent activation energy (calculated at unit shear rate) increases from 123 ± 10 kcal mol−1 to 452 ± 21 kcal mol−1. When the change in liquid composition along the liquidus is included, the observed viscosities are in good agreement with those calculated from the Einstein-Roscoe equation for a serial size distribution of crystals. A quadratic fit to the shear stress-strain rate data yields a nonzero intercept indicative of a finite yield strength. The apparent yield strength increases with decreasing temperature reaching ≈800 Pa at 1149°C. These extrapolated (and model dependent) values are in good agreement with those determined by other methods (Shaw et al., 1968; McBirney and Murase, 1984). The yield strengths can be fit by a power law expression, σ0 = 6500Φ2. 85, where σ0 is the yield strength and Φ the crystal volume fraction. This expression recovers the yield strength estimates for other basalts, suggesting that it may be generally applicable to magmas in which the melt is of broadly basaltic composition. The magmas exhibit heating due to viscous dissipation during shearing. However, this effect is not large enough to produce the observed pseudoplasticity. We conclude that the non-Newtonian behavior in these magmas is due to reorientation of solids in the flow field and solid-solid interactions. We develop a model in which the time-dependent pseudoplasticity and yield strengths are produced by the relationship between solid phase contiguity (the fraction of solid internal surface area snared with other solids) and grain dispersive pressure due to shearing. Increased contiguity is related to increased apparent viscosities and yield strengths, while increased grain dispersive pressure due to shearing acts to diminish contiguity.
Operational wide-area stem volume estimation based on airborne laser scanning and national forest inventory data

This paper evaluates the performance of a recently developed approach for wide-area stem volume estimations based on airborne laser scanning (ALS) and national forest inventory (NFI) data in the case where data recorded under operational conditions are used as input. This entails that neither ALS data nor NFI samples were collected and optimized for the current study. The approach was tested for the Austrian state of Vorarlberg, which covers an area of 2601 km2 and encloses about 970 km2 of forest land. ALS data with point densities varying between 1 and 4 points m−2 were acquired in the framework of a commercial state-wide terrain mapping project during several winter- and summer-flight campaigns. The stem volume model was calibrated with all NFI data available for Vorarlberg, whereas additional local forest inventory data were used for independent validation. Moreover, several relevant operational issues were addressed in this study, such as the determination of the optimum area used to calculate the reference laser metrics input to the model, the effect of gridding point cloud data to speed up processing, and the stratification of input data into coniferous and deciduous sample plots. Without tree species stratification and based on the 3D laser heights model, calibration provided a maximum R2 of 0.79 and a standard deviation (SD) of residuals derived from cross-validation of 107.4 m3 ha−1 (31.5%). Calibrating the model only with coniferous samples increased the achieved R2 to 0.81 and decreased SD to 104.8 m3 ha−1 (29.7%). As only eight NFI sample plots were available for deciduous forest a robust calibration of a separate model could not be obtained. Calibrating the model with a rasterized canopy height model (CHM) instead of using the 3D laser heights just led to a slight decrease in accuracy (R2 = 0.75, SD = 120.9 m3 ha−1 (35.5%) without forest-type stratification and R2 = 0.78 and SD = 117.2 m3 ha−1 (33.1%) for the coniferous stem volume model). Finally, the stem volume model calibrated with CHM data was adopted to generate a stem volume map of the entire State of Vorarlberg. Validation of this map with the additional local forest inventory data confirmed the accuracies (R2 = 0.75; SD = 135.6 m3 ha−1 (32.3%)) that were derived during calibration of the stem volume model based on the NFI data. The models and methods presented in this study are used operationally for forest and environment policy purposes and practical applications in Austria.
Sea ice motion from low-resolution satellite sensors: An alternative method and its validation in the Arctic

[1] The retrieval of sea ice motion with the Maximum Cross-Correlation (MCC) method from low-resolution (10–15 km) spaceborne imaging sensors is challenged by a dominating quantization noise as the time span of displacement vectors is shortened. To allow investigating shorter displacements from these instruments, we introduce an alternative sea ice motion tracking algorithm that builds on the MCC method but relies on a continuous optimization step for computing the motion vector. The prime effect of this method is to effectively dampen the quantization noise, an artifact of the MCC. It allows for retrieving spatially smooth 48 h sea ice motion vector fields in the Arctic. Strategies to detect and correct erroneous vectors as well as to optimally merge several polarization channels of a given instrument are also described. A test processing chain is implemented and run with several active and passive microwave imagers (Advanced Microwave Scanning Radiometer-EOS (AMSR-E), Special Sensor Microwave Imager, and Advanced Scatterometer) during three Arctic autumn, winter, and spring seasons. Ice motion vectors are collocated to and compared with GPS positions of in situ drifters. Error statistics are shown to be ranging from 2.5 to 4.5 km (standard deviation for components of the vectors) depending on the sensor, without significant bias. We discuss the relative contribution of measurement and representativeness errors by analyzing monthly validation statistics. The 37 GHz channels of the AMSR-E instrument allow for the best validation statistics. The operational low-resolution sea ice drift product of the EUMETSAT OSI SAF (European Organisation for the Exploitation of Meteorological Satellites Ocean and Sea Ice Satellite Application Facility) is based on the algorithms presented in this paper.
One-dimensional model for transient flows involving bed-load sediment transport and changes in flow regimes

This study presents a novel, simple, but rather accurate approximation of the eigenvalues of the system formed by the Saint-Venant-Exner equations, based on the comparison between eigenvalues for the complete system and eigenvalues for the water phase only. Moreover, a strategy is proposed to compute efficiently the intercell fluxes by properly adapting a Harten, Lax, and van Leer scheme for each equation. Two examples of transient transcritical flows are developed: the erosive migration of a knickpoint induced by an increase in the bed slope, and the evolution of a hydraulic jump over a mobile bed.
SLOPE SYSTEM RELIABILITY WITH GENERAL SLIP SURFACES

ABSTRACT The main requirements for assessing the system reliability of slopes are outlined briefly and a comprehensive procedure is presented based on potential slip surfaces of arbitrary shape. The evaluation of system reliability of soil structures such as slopes is important because of the spatial variability of geotechnical parameters within any soil layer and also the fact that slopes are frequently associated with multi-layered soil deposits. The performance function for the stability of a slope, defined in terms of a ‘factor of safety’, is usually inexplicit and non-linear. A ‘rigorous’ method of slope stability analysis such as the Generalised Procedure of Slices may be used as the basis of a reliability analysis. A complete analysis should include the search for a critical slip surface and the calculation of reliability index or the probability of failure associated with it. System reliability bounds are evaluated by considering the probabilities of failure associated with a number of slip surfaces including the critical slip surface. It is shown that the upper bound of the system failure probability can be significantly higher than the failure probability associated with the critical slip surface. This finding is significant for slope design and for geotechnical risk assessment generally.
Marine and nonmarine systems tracts in fourth-order sequences in the Early-Middle Cenomanian, Dunvegan Alloformation, northeastern British Columbia, Canada

Abstract The Early to Middle Cenomanian Dunvegan Alloformation is a 3rd-order clastic sequence that was deposited on the western margin of the Alberta foreland basin. The alloformation, comprising ten allomembers (A-J) has been mapped over 33 000 km2 using 1500 well logs and 40 outcrops. Regional flooding surfaces are used to define allomembers because they are more reliably identified in well logs than are Exxon-type unconformities (although in many instances unconformities and flooding surfaces are coplanar). The Dunvegan records episodic deltaic progradation from NW to SE along the axis of the foreland basin. This paper focuses on an 800 km2 study area in NE British Columbia where both shallow marine and coastal plain strata are exposed in the valleys of the Peace and Beatton rivers. Marine strata comprise sandier-upward successions that grade from platy mudstone through cm-scale interbeds of wave rippled fine sandstone to dm-scale beds of HCS, commonly including large gutter casts. Successions may be capped by SCS and cross-bedded, fine-grained sandstone, sometimes with a rooted top. The succession of facies suggests a strongly wave-influenced deltaic shoreline. Gutter casts are consistently orientated shore-normal and appear to have been formed by oscillatory wave scour during storms. Sandstone distribution varies between successive progradational packages (‘shingles’) in allomember J, suggesting that delta switching was an important control on depositional cyclicity. Coastal plain deposits include small-scale (few metres) coarsening-upward successions of carbonaceous mudstone, siltstone and fine sandstone interpreted as lake and bay-fill deposits. Decimetre scale sharp-based sandstones may represent crevasse splays whereas lenticular, rippled and crossbedded sandstones were probably deposited in distributary channels. Rooted palaeosols are abundant. Both coastal plain and marine strata are locally replaced by erosive-based bodies of cross-bedded sandstone up to 25 m thick and 0.5–3 km wide, interpreted as incised valley fills underlain by type 1 sequence boundaries. Additional evidence of relative sea-level fall is provided by regressive surfaces of marine erosion beneath sharp-based shoreface sandstones. If attached to highstand deposits, these sandstones are assigned to the falling stage systems tract, whereas detached sandstones are assigned to the lowstand systems tract. During the early part of the transgressive systems tract, sedimentation was confined to incised valleys but later, interfluves were buried by sediments that locally contain dense Thalassinoides burrow systems, Teredolites and well-developed mud drapes, suggestive of brackish, tidally-influenced conditions. Overlying coastal plain strata lack evidence of marine influence and are attributed to the highstand systems tract.
Evidence for wind-driven current fluctuations in the eastern North Atlantic

Evidence is presented for local and remote wind-forcing of deep ocean currents in three frequency bands (corresponding to 3.7–8 day, 8–22 day, and 23–82 day periods) at a two-year mooring in the eastern North Atlantic. Coherence between current meter velocities and estimated wind stress curl is largest for the deepest instrument (3000 m) and decreases toward the surface. The strongest evidence is found at 3000 m depth in the high frequency (3.7–8 day) band, where both components of velocity are significantly coherent with wind stress curl. Meridional velocity at 3000 m is also significantly coherent with wind stress curl in the low frequency (23–82 day) band, while zonal velocity in the low frequency band and both velocity components in the intermediate frequency (8–22 day) band are only marginally coherent. The results are compared with a stochastically-forced linear quasi-geostrophic model that includes a simple representation of the mid-Atlantic Ridge. Good agreement between predicted and observed coherences is found for the 3000 m currents in the high frequency band, but only partial agreement is found between predicted and observed coherences in the low frequency band, and little agreement in the intermediate band. Kinetic energy levels at 3000 m are well predicted in all three bands. For the shallower instruments (1100 m and 500 m), observed coherences are at most marginally significant and energy levels are considerably higher than the theory predicts. Including an upper-layer mean flow in the model improves the prediction of energy levels at the shallower instruments.
Case study on seismic tunnel response

This paper presents a case study of the Bolu highway twin tunnels that experienced a wide range of damage during the 1999 Duzce earthquake in Turkey. Attention is focused on a particular section of the left tunnel that was still under construction when the earthquake struck and that experienced extensive damage during the seismic event. Static and dynamic plane-strain finite element (FE) analyses were undertaken to investigate the seismic tunnel response at two sections and to compare the results with the post-earthquake field observations. The predicted maximum total hoop stress during the earthquake exceeds the strength of shotcrete in the examined section. The occurrence of lining failure and the predicted failure mechanism compare very favourably with field observations. The results of the dynamic FE analyses are also compared with those obtained by simplified methodologies (i.e., two analytical elastic solutions and quasi-static elastoplastic FE analyses). For this example, the quasi-static racking a.
Response of the climate system to aerosol direct and indirect forcing: Role of cloud feedbacks

[1] In this study, the response of the climate system to aerosol direct and indirect radiative forcing is investigated. Several multidecadal equilibrium simulations are carried out, using the NCAR CCM3 framework coupled to a separately developed aerosol treatment. The aerosol treatment includes, e.g., a life cycle scheme for particulate sulfate and black carbon (natural and anthropogenic), calculations of aerosol size distributions and CCN activation, as well as computations of direct and indirect forcing (1st and 2nd indirect effect). In all the simulations the full aerosol treatment is run online, hence responding interactively to changes in climate. By far the largest response is caused by the indirect forcing, with a globally averaged cooling of −1.25 K due to anthropogenic aerosols. The largest temperature reduction is found in the Northern Hemisphere because of a larger aerosol burden there. As a result of this cooling pattern, the Intertropical Convergence Zone is displaced southward by a few hundred kilometers. Interestingly, a similar, though less significant displacement is also found in the experiments with the direct effect alone, even though the globally averaged aerosol induced cooling is much weaker in that case, i.e., −0.08 K. The direct radiative forcing is much stronger at the surface than at the top of the atmosphere, and this leads to a slight weakening of the hydrological cycle. Comparing simulations with direct and indirect forcing combined to those with indirect and direct forcing separately, a residual, caused by nonlinear model feedbacks, is manifested through a reduction in precipitation. This reduction amounts to −0.5% in a global average and exceeds −2.5% in the Arctic, highlighting the role of high-latitude climate feedbacks. Globally, cloud feedback is negative in the sense that in the colder climate resulting from anthropogenic aerosol forcing, net cloud forcing is reduced by 15% compared to the original climate state. This is caused by a general cloud thinning, especially at high latitudes, while in the most polluted regions, clouds are thicker through the 2nd indirect effect. The 1st indirect effect, on the other hand, remains intact in the presence of climate feedbacks, yielding a similar signature of cloud droplet reduction as in the pure forcing simulations.
Why do Giant Earthquakes Occur at Lunar Phases Specific to Each Subduction Zone

To clearly show the dangerous lunar phases during which giant earthquakes tend to occur at each subduction zone and to clarify the mechanisms of giant earthquake occurrences during neap tides at some subduction zones, the folded and double-folded lunar phase is introduced. The dangerous lunar phases for each subduction zone, represented as delays from spring tides, are 1 to 4 days for Peru, 3 to 5 days for Indonesia, 5 to 7 days for Tonga, 3 to 8 days for Japan, 8 to 11 days for Kuril, -3 to 0 days for Chile, -2 to 0 days for New Guinea, and -2 to 0 days for Alaska. Paying sufficient attention to foreshocks and various precursors such as GPS (Global Positioning System) anomalies during the dangerous lunar phase for each subduction zone will be a very useful way to reduce damage from giant earthquakes. The influence of the solid tidal stress on reverse faulting was investigated based on the strike of subduction zones, and prohibition of giant earthquakes caused by strength increase due to the rapid variation in tidal stress during spring tides at NS subduction zones was proposed as one reason why giant earthquakes occur not only at spring tides but also at neap tides at some subduction zones.
Man-Made Deserts: Desertization Processes and Threats

Desertization is defined as the irreversible extension of desert land forms and landscapes to areas where they did not occur in a recent past. Such extension does not result from a would-be increasing aridity as there is no evidence of any global long-term trends in rainfall in arid lands since the period of instrumental record (ca. 150 years). The 0.5° C of global temperature increase over the past 100 years remains well within the range of historical fluctuations. The creation of man-made deserts is actually the result of long-lasting mismanagement of natural resources under the pressure of excessive human and livestock populations. Such land abuse may drive ecosystems beyond their resilience potential for recovery. The causes and mechanisms of arid land degradation pertain to direct and indirect activities, processes, and phenomena, which are not necessarily linked to aridity or drought. Causes, severity, and extent of desertization are quantified from various sources. The potential for biological reco.
Effects of pile shape in improving the performance of monopiles embedded in onshore clays

This paper presents the results from a series of three-dimensional finite element analyses, which examine the benefits of adopting square pile–tower structures instead of circular monopiles. The advantages of square monopiles are brought out in this paper through a parametric study with a Tresca soil model, where the shear strength and modulus of elasticity varied with depth and the pile–tower structures were modelled as an elastoplastic material. The effects of pile diameter, pile thickness, eccentricity, and pile length for free-head pile–towers embedded in lightly overconsolidated and heavily overconsolidated clays were investigated. From the results of the numerical models, it is clear that the ultimate lateral capacity and stiffness of square pile–tower structures are substantially higher than of circular structures embedded in clay layers. Moreover, the amount of rotation and displacement of square structures are not significantly affected compared to circular monopiles.
Directional Spreading of Short Wavelength Fetch-Limited Wind Waves

Abstract Observations of the spreading of short-wavelength (5 m) wind waves have been made with a steerable HF ocean surface radar in the nearshore zone in a stable offshore airflow. The directional spreading lobe is significantly broader than that predicted from the model by Hasselmann et al. It appears that the spreading lobe is broader at high frequencies (f≈0.56 Hz) than at lower frequencies (0.2<f<0.5 Hz) for f/fm ratios near unity in a fetch-limited wind wave spectrum which has a peak at frequency fm.