Miracle-dz/UniFAR-FTUs huggingface dataset:
Soil carbon stabilization in converted tropical pastures and forests depends on soil type

The influence of soil C stabilization mechanisms is normally not considered in studies on the effects of land use changes. Instead, observed changes are typically explained by differences in litter input. As a result, it is not well known if and how quickly newly incorporated C is stabilized in soils. Our goals were to find out how much soil C was stabilized in two different soil orders (Andisols and Inceptisols) and which are the responsible mechanisms of C stabilization. Furthermore, we looked for evidence that newly incorporated soil C was stabilized in these contrasting soil orders. We selected 25 sites in north-western Ecuador with two paired plots per site: one plot where pasture was converted to secondary forest and one plot where forest was converted to pasture. In all the plots, soil C content, stocks, and stable isotope (δ 13 C) signal were measured in the surface soil. The δ 13 C values were used to estimate the stocks of soil C derived from forest (Cdf) and from pasture (Cdp) in all plots. We calculated correlations between these stocks and soil and environmental characteristics to identify mechanisms of soil C stabilihition. Our results show that long-term stabilization in Andisols was through formation of metal-humus complexes and allophane, while in Inceptisols long-term stabilization was through sorption to day minerals. We found evidence that recently incorporated C was not stabilized in Andisols, while in Inceptisols, poorly crystalline (hydr-) oxides seemed to have stabilized part of this soil C. We conclude that unless soil C stabilizing mechanisms are explicitly considered, we will not be able to predict the direction and magnitude of changes in soil C stocks following land use changes in the tropics.
Modal Aerosol Dynamics Modeling

ABSTRACT The derivation of the governing equations for modal aerosol dynamics (MAD) models is presented. MAD models represent the aerosol size distribution as an assemblage of distinct populations of aerosol, where each population is distinguished by size or chemical composition. The size distribution of each population is approximated by an analytical modal distribution function; usually by a lognormal distribution function. By substituting the MAD representation of aerosol size distributions into the governing equation for aerosol processes, the governing differential equations for MAD models are derived. These differential equations express the time dependence of the moments of the aerosol size distribution and are called Moment Dynamics Equations (MDEs). The MDEs for Continuously-Stirred Tank Aerosol Reactors (CSTARs) are also derived.
Recent Warming in the Western North Pacific in Relation to Rapid Changes in the Atmospheric Circulation of the Siberian High and Aleutian Low Systems

AbstractOn the basis of a new East Asian winter monsoon (EAWM) index and by analyzing the relationship between sea surface temperature (SST) anomalies and different atmospheric and oceanic factors in winter, this study investigates the causes of the recent unusual warming in the western North Pacific Ocean. Analyses presented here emphasize the dual contribution from the atmosphere and ocean to the local SST variability, with the relative importance of each contributor varying with the period and place. During the period 1970–89, the EAWM, controlled mostly by the Siberian high, is predominantly responsible for the SST variability in most of the western North Pacific, whereas in the period 1990–2005 ocean dynamics become increasingly important in most places or even dominant in the Kuroshio–Oyasio Extension (KOE) region. The delayed response of the KOE SST to basinwide wind stress curl forcing via Rossby waves is epoch dependent and is significant at lags of 1, 3, and 4 yr before 1990 but only at 1 yr aft.
Observations of electromagnetic ion cyclotron waves during geomagnetic storms: Wave occurrence and pitch angle scattering

This paper addresses the occurrence of low-L (3.5 < L < 5) electromagnetic ion cyclotron (EMIC) waves during magnetic storms. Using ∼10 years of data, a statistical analysis indicates that EMIC waves in the equatorial magnetosphere occur 5 times more often during magnetic storms than during quiet times. EMIC wave occurrence during magnetic storms is important because EMIC waves pitch angle scatter energetic protons and thus represent a ring current loss mechanism. Observations in the equatorial magnetosphere, acquired by the Dynamic Explorer 1 (DE 1) satellite, are used to show the simultaneous occurrence of EMIC waves and enhanced proton fluxes in the loss cone. The study involves three cases selected only on the basis of observed EMIC wave activity and the availability of energetic ion data. The observations show that EMIC waves indeed scatter protons into the loss cone. Model calculations of the loss cone heat-flux density compare favorably to the observed proton flux in the loss cone. These calculations are then used to estimate the effect of EMIC waves on ring current energy loss, assuming an effective area of wave activity and the duration of the wave activity. It is found that large-amplitude, long-duration EMIC waves can produce the observed recovery in the Dst index.
Hydrology and change

Abstract Since “panta rhei” was pronounced by Heraclitus, hydrology and the objects it studies, such as rivers and lakes, have offered grounds to observe and understand change and flux. Change occurs on all time scales, from minute to geological, but our limited senses and life span, as well as the short time window of instrumental observations, restrict our perception to the most apparent daily to yearly variations. As a result, our typical modelling practices assume that natural changes are just a short-term “noise” superimposed on the daily and annual cycles in a scene that is static and invariant in the long run. According to this perception, only an exceptional and extraordinary forcing can produce a long-term change. The hydrologist H.E. Hurst, studying the long flow records of the Nile and other geophysical time series, was the first to observe a natural behaviour, named after him, related to multi-scale change, as well as its implications in engineering designs. Essentially, this behaviour manifests that long-term changes are much more frequent and intense than commonly perceived and, simultaneously, that the future states are much more uncertain and unpredictable on long time horizons than implied by standard approaches. Surprisingly, however, the implications of multi-scale change have not been assimilated in geophysical sciences. A change of perspective is thus needed, in which change and uncertainty are essential parts. Editor Z.W. Kundzewicz Citation Koutsoyiannis, D. , 2013. Hydrology and change. Hydrological Sciences Journal, 58 (6), 1177–1197.
Laboratory investigations of effective flow behavior in unsaturated heterogeneous sands

Two‐dimensional unsaturated flow and transport through heterogeneous sand was investigated under controlled laboratory conditions. The unsaturated hydraulic conductivity of five homogeneous sands and three heterogeneous systems composed of these five sands was measured using a steady state flux controlled method. The heterogeneous sand systems were established in a laboratory tank for three realizations of random distributions of the homogeneous sands comprising a system of 207 grid cells. The water flux was controlled at the upper boundary, while a suction was applied at the lower boundary such that on the average a uniform pressure profile was established and gravity flow applied. Solute breakthrough curves measured at discrete points in the tank using time domain reflectometry, as well as dye tracer paths, showed that flow and transport took place in a very tortuous pattern where several grid cells were completely bypassed. The degree of tortuosity appeared to be dependent on the degree of saturation, as the tortuosity increased with decreasing saturation. Despite the tortuous flow patterns, we found that the effective unsaturated hydraulic conductivity as well as the retention curves for the three realizations of the heterogeneous sand were quite similar, thus suggesting that this type of heterogeneous flow system can be treated as an equivalent homogeneous medium characterized by effective parameters.
Flood frequency estimation by continuous simulation under climate change (with uncertainty)

Abstract. This paper explores the potential for assessing the impacts of climate change upon flood frequency for the gauged, upland Wye catchment at Plynlimon, Wales, UK, while taking account of uncertainty in modelling rainfall-runoff processes under current conditions. A continuous simulation methodology which uses a stochastic rainfall model to drive the rainfall-runoff model TOPMODEL is utilised. Behavioural parameter sets for both the rainfall model and TOPMODEL are identified prior to the climate change runs using the Generalised Likelihood Uncertainty Estimation (GLUE) methodology. The "medium-high" UKCIP98 climate change scenario, obtained from the HadCM2 GCM simulations, is used as a starting point for a variety of different scenarios at the catchment scale. It is demonstrated that while the scenarios have only a small impact upon the likelihood weighted flood frequency uncertainty bounds in comparison with the current condition scenario, the risk of a given discharge as an element in the distribution of T year floods is changed. This underlines the need to account explicitly for uncertainty within hydrological modelling, especially in estimating the impacts of climate change. Keywords: Climate change; Floods; Frequency; TOPMODEL
The Pivot of the Four Quarters: A Preliminary Enquiry into the Origins and Character of the Ancient Chinese City

This book is an attempt to elucidate the manner in which there emerged, on one part of the North China plain, during the 2nd millenium BC, hierarchically structured, functionally specialized social institutions organized on a political and territorial basis, and to describe the way in which, during subsequent centuries, they were diffused through much of the rest of North and Central China.
A Logit Model for Predicting the Daily Occurrence of Human Caused Forest-Fires

The logit model was used to predict the number of fire-days in the Whitecourt Forest of Alberta. The database used included fire (1) and no-fire (0) observations for fire season days between April and October for the 1986 through 1990 period. There were 8,009 observations during this period of which 157 were fire observations. Using four variables, we were able to predict 79.0% of the fire-days and 81.5% of the no-fire-days. The model, Zi=-8.5171+7.6590xAREAi+0.7367xDISTRICTi+2.0478xBUIi+3.9563xISIi, failed to predict 37 of the fire-days and produced 29 ''false alarms''. When this model was tested on fire occurrence data from the Whitecourt Forest for 1991 and 1992 fire seasons it was correct 74.1% of the time. The management implications and limitations of this study are also discussed in this paper.
Geomagnetic Secular Variation at the Indian Observatories

Annual mean values of geomagnetic field components D, H and Z for all days and quiet days at six observatories are analysed to investigate the secular variations and geomagnetic jerks in the Indian region. Secular trends show a region of demarkation between equatorial and low latitude stations. The residual D, H and Z curves, obtained by removing polynomial fits, do not show any parallelism with the Il-year sunspot cycle. However, the D residual has a periodicity of 2 solar cycles, whereas H and Z residuals indicate a quasi-periodicity of 3 solar cycles at Alibag. For the period 1958 to 1990, D and Z residuals show a periodicity of nearly 2 solar cycles, while H shows out-of-phase variations with the sunspot cycle for all the six stations. The secular jerk around 1969-70, noted at many observatories over the globe, is not seen in D but is noted in the H and Z components at some of the six Indian stations. A comparison between the observed annual means and IGRF models indicates very low secular variation anomaly in the Indian region.
A Modified Inertial Dissipation Method for Estimating Seabed Stresses at Low Reynolds Numbers, with Application to Wave/Current Boundary Layer Measurements

Abstract The inertial dissipation method for estimating seabed friction velocities from near-bed turbulence spectra requires few measurements; it is relatively insensitive to errors in sensor orientation and measurement of mean flows. However, the method is only valid if turbulence spectra are measured at a height above the seabed that is small enough to be within the constant stress layer but large enough to produce an inertial subrange. It is shown that such a height exists only if the friction velocity exceeds a critical value (typically 0.8 cm s−1 for a midlatitude ocean). Recent measurements from combined wave and mean flow conditions on the continental shelf do not satisfy this requirement. However, an empirical modification to the inertial dissipation method is suggested to allow estimation of the friction velocity even when a true inertial subrange does not exist. The modified method is applied to the combined wave and mean flow field data; it virtually removes an increase in estimated friction ve.
Flume Studies of the Sediment Transfer Coefficient

Flume experiments show that in open channel flow the sediment transfer coefficient increases with distance from the channel bed, reaching a maximum value at a distance from the bed equal to about 20% of the flow depth, and then tends to remain at a constant value up to the water surface. The experiments also yield evidence indicating that the sediment transfer coefficient is larger for larger particle sizes.
Oxygen isotope composition of stratospheric carbon dioxide

Heavy oxygen isotope enrichment in stratospheric CO2 has been identified in the past as a direct result of the large O3 isotope anomaly though no simultaneous measurements are known. Results from 8 stratospheric balloon flights at two latitudes are reported that provide now a complete oxygen isotope analysis of both gases. An unambiguous, very tight correlation between enrichments of 17O and 18O in CO2 has been found. The large ratio δ17O/δ18O of 1.71 ± 0.03 shows a faster transfer of 17O than of 18O into CO2 and establishes a standard throughout the lower and middle stratosphere between midlatitudes and high northern latitudes. Ozone isotope transfer can now be treated in models with reliable atmospheric data.
Mapping Pedestrian Journey Times using a Network-based GIS Model

Abstract Please click here to download the map associated with this article. Pedestrian accessibility maps often display a Euclidean distance (straight line between two points) buffer around a destination. This paper presents a map that demonstrates how a pedestrian network can be used to improve the accuracy of these results and model the effect of gradient and demographics on walk speed. A bespoke GIS model was developed to undertake the assessment, which is explained along with the key assumptions made. The model was used to assess pedestrian access levels from five proposed development sites in the West Northamptonshire area to the key local facilities. The results quantified access using defined threshold journey times to provide the percentage of dwellings within this limit. This helped West Northamptonshire Development Corporation to consider the specific pedestrian access issues that each site may have, which forms part of their process of delivering sustainable development. The model developed could be applied to other geographical regions and scenarios. More generally, the study showed that GIS is a key tool for improving the evidence base as part of the spatial planning process.
The Most Extreme Precipitation Events over the Eastern United States from 1950 to 1996: Considerations of Scale

Abstract The intensity or magnitude of a given heavy precipitation event is typically associated with the greatest point precipitation total. The scale or size of the heavy precipitation region, however, is important because it affects the scale of the flooding potential (e.g., local- vs regional-scale basins). In this study, a heavy-rain climatological description is constructed that identifies all precipitation events for the period of 1950–96 and estimates the heaviest mean 2-day precipitation totals over a range of spatial scales (i.e., circular regions from 2500 to 500 000 km2). Ranks of the most extreme precipitation events are provided for four regions of the study area for each of the 10 spatial scales. To develop the dataset, daily precipitation totals from the cooperative observer network are spatially interpolated onto a finescale (10 km by 10 km) grid over the eastern two-thirds of the United States. An automated algorithm is developed 1) to identify regions displaying the greatest mean 2-day .
Neuroemulation: definition and key benefits for water resources research

Abstract Neuroemulation is the art and science of using a neural network model to replicate the external behaviour of some other model or component of a model. It is an independent activity that is distinct from neural network-based simulation. Neuroemulation has become a recognized and established sub-discipline in many spheres of study, but remains poorly defined in the field of water resources research. Its many potential benefits have not yet been adequately recognized or established. Lack of recognition can in part be attributed to difficulties involved in identifying, collating and synthesizing published studies on neuroemulation: query-based searching of a publications database fails to identify papers concerned with a field of study, for which no agreed conceptual and/or terminological framework as yet exists. Therefore, in this paper, we provide a first attempt at defining such a framework for use in water resources investigations. We identify eight key benefits offered by neuroemulation and exemplify current activities with relevant examples taken from published research in the field. The concluding section highlights a number of strategic research directions related to developing the identified potential of neuroemulator applications for water resources modelling. Editor D. Koutsoyiannis Citation Abrahart, R.J., Mount, N.J. and Shamseldin, A.Y. , 2012. Neuroemulation: definition and key benefits for water resources research. Hydrological Sciences Journal, 57 (3), 407–423.
Limits of stresses in continental crusts and their relation to the depth-frequency distribution of shallow earthquakes

Based on published results of experiments on low-temperature, low-pressure frictional sliding and creep at higher temperature and pressure, theoretical curves of yield strength versus depth corresponding to maximum crustal stresses (STRESSMAX) are calculated. These curves are compared to the frequency-depth distribution of earthquakes (DEFREQ) in several tectonic areas. Both sets of curves have a very similar form and show a prominent peak. From the similarity it is concluded that it is basically the temperature and the water content of the entire crust, not the properties of a particular layer, which determine the shape of maxima of the DEFREQ curves. The peaks of DEFREQ curves are generally at 5- to l0-km depth and agree with STRESSMAX peaks of wet upper crust only. At this depth range the high stresses provide an increased ‘cracking potential’, resulting in an increased number and an increased stress drop of earthquakes. More and stronger barriers/asperities seem to exist at these depths, causing large earthquakes to nucleate in this high-strength region. The stresses required to overcome the strength maximum are built up from below by ductile creep. The lower crust is considered to be a stress and viscosity minimum; in orogenic zones, strong interaction with plumes from the mantle may take place, and lateral movements are probable.
Microtremor analysis over carbonates with and without oil

, 2010). In this paper, we analyse two different sets of passive seismic data acquired in areas of outcropping carbonate rocks, one in Italy and one in Saudi Arabia. The second area is located over a semi-depleted oil reservoir, which still could be produced by enhanced oil recovery techniques. In the first area, instead, there is no oil at all. e compareW some signals features in the two cases to check the possibility of using microtremors as a diagnosti c tool for detecting hydrocarbons.
EFFECTS OF CORIOLIS FORCE ON CURRENT AND SUSPENDED SEDIMENT TRANSPORT IN THE COASTAL ZONE OF RED RIVER DELTA

This paper presents some results of three dimensional (3D) modelling application to research effects of Coriolis force on field current and suspended sediment transport in the coastal area of Red River delta. In this study, a 3D numerical model was set up, calibrated and validated by measured data. Two simulation groups were set up: with Coriolis force and without Coriolis force in the model. The studied results show that the Coriolis force is factor, which causes and strengthens flows alongshore, increases current velocity in coastal zone of Van Ly - Hai Hau. This factor also increases alongshore water and suspended sediment flux from north to southwest with the variation in each cross sections. The results have also shown the role of Coriolis force on the lack of sediment in coastal area of Van Ly - Hai Hau in the rainy season.
The effects of slope and fuel bed width on laboratory fire behaviour

A set of 109 laboratory fires in Pinus halepensis fuel beds (1 kg m–2) was used to test the effects of slope (0°, 10°, 20°, 30°) and fuel bed width (1, 2, 3 m) on fire behaviour variables such as rate of spread, fuel consumption, flame residence time, temperatures and flame geometry. The qualitative behaviour of the fires is also reported. The 20° and 30° upslope fires are pointed in shape and fire whirls moving along the fire flanks in the direction of the fire head are systematically observed in 30° upslope fires. Flame residence time increases with increasing slope angle, and both slope angle and fuel bed width affect rate of spread. The slope effects observed in 10° and 20° slope angles and in the narrowest fuel beds (1 and 2 m) are similar to those predicted by operational models. However, the observed slope effect at the 30° slope angle is underestimated by these models, in particular in 3 m-wide fuel beds. Flame temperatures correlate closely with dimensionless height and flame lengths correlate closely with fire line intensity. Mechanisms that could explain the different effects observed are suggested and discussed.
Pteridófitas do Parque Estadual de Vila Velha, Ponta Grossa, Paraná, Brasil

In this work we present a floristic survey of the pteridophytes from the Vila Velha State Park, Ponta Grossa, Parana. Vila Velha presents an area of 3,803.28 ha, altitudes varying from 800 to 1,100 m and it is mainly represented by natural grasslands surrounding Araucaria forest' spots and the peculiar sandstone formations arised. We have found 152 species, distributed in 54 genera, being Asplenium (11 spp.), Blechnum and Thelypteris (10 spp. each), Pecluma, Polypodium and Trichomanes (7 spp. each) the richest genera. One hundred species were found in the forests, 47 in the grasslands and 60 in the sandstone formations. Twenty-seven species are restricted to Brazil, of which 14 are endemic to the southeast and south Brazil. Special mention is made to Ctenitis bigarellae Schwartsburd et al., Elaphoglossum langsdorffii (Hook. & Grev.) T. Moore, Alsophila capensis subsp. polypodioides (Sw.) Conant and Blechnum australe subsp. auriculatum (Cav.) de la Sota. Identification keys, comments and list of specimens are also presented.