Miracle-dz/UniFAR-FTUs huggingface dataset:
Formation of maximum electric potential at the geomagnetic equator by the disturbance dynamo

[1] The effect of a disturbance dynamo during geomagnetic activity on the equatorial ionospheric electric fields is investigated, using model results from the NACR/TIEGCM (National Center for Atmospheric Research Thermosphere Ionosphere Electrodynamics General Circulation Model). Model runs are made for different time-lengths of geomagnetic activity, for different seasons, and for different solar activities to investigate how and where the maximum electric potential forms. Model results show that the maximum electric potential is located at around 300 km altitude and at local time after the pre-reversal enhancement at equinox for high solar activity. For the case at solstice, without pre-reversal enhancement, the location moves to around 110 km altitude and to the local time close to midnight. Giving various parameters in the model runs to simulate different background conditions, many important output quantities are used to study the distributions of perturbed electric potential at the geomagnetic equator. Model investigation indicates that normal quiet time electrodynamics, at different seasons with different solar activities, significantly affect the distribution of perturbed current density associated with geomagnetic activity. Furthermore, model results also reveal that significant perturbed zonal electric fields tend to build up six hours after the onset of geomagnetic activity, except at regions close to sunset and sunrise, and the perturbed vertical electric fields increase with the time length of geomagnetic activity.
DROPPS: A study of the polar summer mesosphere with rocket, radar and lidar

DROPPS (The Distribution and Role of Particles in the Polar Summer Mesosphere) was a highly coordinated international study conducted in July, 1999 from the Norwegian rocket range (Andøya, Norway). Two sequences of rockets were launched. Each included one NASA DROPPS payload, containing instruments to measure the electrodynamic and optical properties of dust/aerosol layers, accompanied by European payloads (MIDAS, Mini‐MIDAS, and/or Mini‐DUSTY) to study the same structures in a complementary manner. Meteorological rockets provided winds and temperature. ALOMAR lidars and radars (located adjacent to the launch site) monitored the mesosphere for noctilucent clouds (NLCs) and polar mesosphere summer echoes (PMSEs), respectively. EISCAT radars provided PMSE and related information at a remote site (Tromsø, Norway). Sequence 1 (5–6 July) was launched into a strong PMSE with a weak NLC present; sequence 2 (14 July) occurred during a strong NLC with no PMSE evident. Here we describe program details along with preliminary results.
Copper in Lake Pontchartrain bottom sediment: Relationship to sediment properties

Several watersheds in the Louisiana Pontchartrain Basin are listed as impaired, with dissolved Cu as one of the impairments. In this study we determine Cu levels in sediment of Lake Pontchartrain (which comprises part of one of the largest estuaries in the Gulf Coast region) which receives water from impaired watersheds. Sediment samples were collected along an 8 km sampling grid (174 sites) and analyzed for total Cu in sediment. The average Cu content in sediment was 13.6 ± 6.7 mg.kg−1 ranging from 0 to 31.5 mg.kg−1 (n = 174). Results show that there was little Cu pollution in the lake sediment. Cu level was correlated with Al content (r = 0.888**) and Fe content (r = 0.907**) of sediment. Higher Cu was also found in sediment with high clay content (r = 0.429**). Cu was inversely correlated with sand content of sediment (r = −0.520**).
PARTICLE CRUSHING AND DEFORMATION BEHAVIOUR

Particle breakage occurs in granular materials with various engineering applications, such as when driving piles (especially where the strength of the particles is low) and in debris flows (where the energy levels are high), and the influence of this breakage on the mechanical behaviour of soils should be given proper consideration in a constitutive model for soils. Particle breakage results in an increase in the number of fine particles and broadens the grading of particle sizes, and the primary effect of broadening the grading is to lower the critical state line and other characteristics of the volumetric response in the compression plane. In our study, an existing constitutive model, the Severn-Trent sand model, in which the critical state line plays a central role as the locus of asymptotic states, has been extended to include the effects of particle breakage. Severn-Trent sand is a frictional hardening Mohr-Coulomb model described within a kinematic hardening, bounding surface framework. The central assumption is that strength is seen as a variable quantity, dependent on the current value of the state parameter (volumetric distance from the critical state line) which varies with changes in density and stress levels. If the critical state line falls as a result of broadening grading, the state parameter tends to increase and the soil feels looser.
GRIPS Solar Experiments Intercomparison Project: Initial Results

The GRIPS solar intercomparison project presented here is part of the “GCM Reality Intercomparison Project for SPARC (GRIPS)” focusing only on the influence of 11-year solar-cycle variations on the atmosphere. The aim of the present comparison is to assess the problems related to the simulation of the solar influence in order to better define future experiments. Results from different GCMs will be presented to investigate whether there is any consistency between them or with existing model studies and observations. Each of the different GCMs used the same wavelength-dependent solar irradiance changes as well as the resulting ozone changes calculated with 2-D chemical models enabling a better intercomparison of the different GCMs. It turns out that each model response is different and that the model results are dependent on the model climatologies that vary widely both among themselves and with observations. One of the major problems encountered during the comparison is the lack of reliable observational evidence for the solar influence on climate (e.g., temperature, ozone). There are also important uncertainties of the forcings used for the model simulations (solar energy spectrum, ozone).
Meteorological and Back Trajectory Modeling for the Rocky Mountain Atmospheric Nitrogen and Sulfur Study II

The Rocky Mountain Atmospheric Nitrogen and Sulfur (RoMANS II) study with field operations during November 2008 through November 2009 was designed to evaluate the composition and sources of reactive nitrogen in Rocky Mountain National Park, Colorado, USA. As part of RoMANS II, a mesoscale meteorological model was utilized to provide input for back trajectory and chemical transport models. Evaluation of the model's ability to capture important transport patterns in this region of complex terrain is discussed. Previous source-receptor studies of nitrogen in this region are also reviewed. Finally, results of several back trajectory analyses for RoMANS II are presented. The trajectory mass balance (TrMB) model, a receptor-based linear regression technique, was used to estimate mean source attributions of airborne ammonia concentrations during RoMANS II. Though ammonia concentrations are usually higher when there is transport from the east, the TrMB model estimates that, on average, areas to the west contribute a larger mean fraction of the ammonia. Possible reasons for this are discussed and include the greater frequency of westerly versus easterly winds, the possibility that ammonia is transported long distances as ammonium nitrate, and the difficulty of correctly modeling the transport winds in this area.
Compressional velocity structure and anisotropy in the uppermost mantle beneath Italy and surrounding regions

Travel times of about 39,000 Pn arrivals recorded from regional earthquakes by the Italian Telemetered Seismic Network and by stations of nearby countries are inverted to image lateral variations of seismic velocity and anisotropy at subcrustal depth in Italy and surrounding regions. This method allows simultaneous imaging of variations of Pn velocity and anisotropy, as well as crustal thickness variations. The Po plain, the Adriatic Sea, and the Ionian Sea have normal to high Pn velocities. In contrast, lower velocities (7.9-8.0 kin/s) are imaged in Italy beneath the western Alps, the northern Apennines, and eastern Sicily and nearby Calabria, as well as in northern Albania and beneath the Pannonian basin. Low Pn velocities beneath the northern Apennines correlate with present-day extension and may have resulted from thermal anomalies in the uppermost mantle possibly due to delamination processes. Low velocities are consistent with the high-attenuation zone inferred in the uppermost mantle beneath the internal Apennine units and the Tyrrhenian margin of the peninsula by Mele et al. (1996, 1997). On the contrary, low velocities beneath the western Alps may be an apparent effect due to the abrupt thickening of the crustal roots. Pn velocity is anisotropic in the study area with a maximum amplitude of + 0.2 km/s. The largest anisotropic velocity anomalies are observed along the major arc structures of Italy, i.e., the northern Apennines and the Calabrian Arc, indicating that these features are controlled by uppermost mantle processes. The anisotropy anomaly along the Calabrian Arc extends as far as Albania but ends abruptly north of this area, suggesting that a lithospheric discontinuity is present along the northern Albanian border.
Secondary currents in a curved, stratified, estuarine channel

This paper presents a study of secondary circulation in a curved stratified channel in northern San Francisco Bay over a 12.5-hour tidal cycle. Secondary currents were strong at times (varying by up to 35 cm/s from top to bottom) but relatively transient, as the balance between centrifugal and lateral baroclinic forcing changed over time. The short travel time around the bend did not allow a steady state balance to develop between centrifugal and lateral baroclinic forcing. During the flood tide the confluence of two streams with different velocities produced a strong lateral gradient in streamwise velocity. As a result, lateral advection was a significant term in the streamwise momentum balance, having the same order of magnitude as the barotropic and baroclinic pressure gradients, and the frictional terms. During the first part of the ebb, secondary currents were induced by lateral baroclinic forcing. The direction of the secondary circulation reversed later in the ebb, as the baroclinic forcing became weaker than the centrifugal acceleration. The gradient Richardson number showed that stratification was stable over most of the tidal cycle, decreasing the importance of friction and allowing secondary currents to persist.
When and why does bioturbation lead to diffusive mixing

Bioturbation in aquatic sediments results from many different biological activities, inducing particle displacement over a variety of length and time scales. Despite this inherent complexity, empirical tracer studies show that bioturbational mixing is often well described by a simple diffusive model. To resolve this apparent contradiction between biological complexity and modeling simplicity, we present an investigation into the diffusive nature of bioturbation. To this end, we examine a stochastic description of bioturbation, where particle mixing is described as a sequence of random bioturbation events. Particle movement is governed by three basic variables: the direction of jumping, the jumping distance, and the waiting time between two bioturbation events. A set of gradually more complex random-walk models is constructed by treating these variables consecutively as stochastic. Each time, the conditions are determined under which these random walks generate diffusive behavior. One important criterion is that the tracer should experience a sufficient number of bioturbation events, and so the time scale of observation should be large enough. The full list of conditions needed to arrive at diffusive mixing is different and more extensive than in past examinations of the topic. This analysis clarifies the relation between the biodiffusion model and more sophisticated mixing models, revealing that the conventional distinction between local and nonlocal models is not entirely relevant. Instead, we propose a distinction between “normal“ or “anomalous“ mixing, which is based on the intrinsic nature of the faunal activities causing particle dispersal. Overall, our analysis provides insight into the conditions under which the biodiffusion model can be applied to tracer profiles, and also shows why it sometimes fails, as is the case of sediments dominated by head-down deposit feeders.
Plate Tectonics: How It Works

Preface Introduction Basics of a revolution Plates in velocity space Getting round on a sphere Wrapping plate tectonics around a globe Plotting planes and vectors in local coordinates Earthquakes and plates Finite rotations Magnetism and isochrons Paleomagnetic poles Putting it all together Absolute Plate Motion Problems Suggested Reading Index Index of References.
The large‐scale circulations and summer drought and wetness on the Tibetan plateau

Effects of large‐scale atmospheric circulation and surface temperatures on extreme dryness and wetness on the Tibetan plateau in summer are analysed using ERA‐40 reanalysis and observed precipitation. The extreme cases of drought and wetness can be associated with circulation anomalies in the North Atlantic/European sector and wave trains bridging the Eurasian continent. Drought in Tibet reveals an intense high pressure anomaly over Scandinavia supported by a more south‐west to north‐east orientated North Atlantic stormtrack. This creates wave trains crossing Eurasia which, on their southward ‘great circle route’, reach south‐eastern Asia where they modulate the flow north and east of the Tibetan plateau by an anticyclone–cyclone dipole suppressing moisture supply from the Bay of Bengal.
Vertical wavenumber spectra of wind and temperature from high-resolution balloon soundings over Illinois

We spectrally analyzed high-resolution balloon measurements of vertical profiles of temperature and horizontal wind in the troposphere and lower stratosphere over very flat terrain in Illinois. This paper is principally concerned with spectra in the power law range at vertical wavenumbers m ≥10−3 cycle/m. The logarithmic spectral slopes and amplitudes are found to have only insignificant dependencies on meteorological parameters, including time of day, season, wind speed and direction, vertical shear, etc., except that between the troposphere and stratosphere the spectral amplitude scales as (N2)q with q ∼0.3, where N is the buoyancy frequency. The mean slopes are ≈−3 in the stratosphere and ≈ −2.6 in the troposphere. On the average the individual spectra with larger amplitudes have less negative spectral slopes. The wide variation of spectral slopes (σ≈0.5) and amplitudes and the weak dependence on N2 are quite inconsistent with the predictions of theories of saturated spectra. Further, the wind spectra in the troposphere and stratosphere are correlated, which suggests some unsaturated propagation between the regions. The ratio of kinetic to potential energy spectra is constant versus m, consistent with the linear gravity wave polarization relations. The magnitude of the model ratio can be brought into agreement with the observed ratio by assuming a model intrinsic frequency spectrum varying as ω−p with p ∼5/3 to 2 plus an enhancement of energy near the inertial frequency.
Autocatalytic release of bromine from Arctic snow pack during polar sunrise

Measurements and modeling studies strongly suggest that spring time depletion of ozone in the Arctic planetary boundary layer (PBL) is due to catalytic destruction by bromine atoms. However, the source of the bromine is uncertain. In this note, we propose that the source of the bromine at polar sunrise is the snow pack on the ice covering Arctic ocean and that it is released auto-catalytically, stimulated by a bromine seed from one of the brominated organic compounds, such as CHBr{sub 3}, by photolysis. In this manner {approximately}100 pptv of bromine can be transferred to the atmosphere where it can reside in the gas phase or, by scavenging, be partitioned in the aerosol or ice crystal phase. Moreover, it appears that heterogeneous recycling of bromine may be a process that self-terminates as ozone depletes to low levels. We also have included chlorine chemistry in the model in order to simulate inferred levels of chlorine atoms. This is important as it results in the production of HCHO which acts to convert post ozone depletion active bromine into HBr which is then returned to the snow pack or scavenged by aerosols or ice crystals. {copyright} American Geophysical Union 1996
Comparison between Parametric and Nonparametric Approaches for the Calculation of Two Drought Indices: SPI and SSI

AbstractA comparison is provided between parametric and nonparametric approaches for the calculation of two drought indices: the standardized precipitation index (SPI) and the standardized streamflow index (SSI). The parametric approach has been implemented considering two possibilities: (1) a unique probability distribution for the variable of interest with parameters depending on the month of the year, and (2) the probability distribution depending on the month of the year. The parameters’ estimation is made using the maximum likelihood method, while the distribution selection is operated using the Kolmogorov-Smirnov goodness-of-fit test. For the nonparametric approach, the Weibull plotting position has been used to calculate the cumulative frequency. For both indices, the 1-month, 3-month, and 12-month time scales have been considered. As a case study, two 80-year-long monthly time series in Italy are considered: Roma Collegio Romano for precipitation, and Tevere River Basin at Ripetta for streamflow, .
Seasonal variations and contributions of cassava to the nutrient intakes of rural farm households

Nutritional assessment of 72 subjects from randomly selected 34 rural farm households of Ohosu community in Edo State, Nigeria was done using anthropometric measurements of weight and height. A four day weighed food intake study was carried out in the months of August (S1), November (S2), February (S3), and May (S4) 1998 - 1999. Analysis of weight for height compared with standards for children and adults showed that 52.78% of the subjects were wasted. The nutrient intakes were below the FAO/WHO requirement values for over 80% of the subjects. The most wide - spread nutrient deficiencies were protein, thiamin and riboflavin. Vitamin A intake was adequate for over 95% of the subjects. Cassava products were consumed by 99% -100% of the subjects in any one day of the seasons. Cassava was the major source of nutrients in their diets. It contributed between 6% and 23% of the daily nutrient intake. The energy intake of women (155.6% of requirement) aged 31-40 years was significantly higher in S1 than in all the other seasons (LSD. 05 = 51.84). Key words: Nutrient intake, seasonal variation, farm households, cassava, supplementary foods. Agro-Science Vol.2(2) 2001: 81-88
A Model Study of the Short-Term Climatic and Hydrologic Effects of Sudden Snow-Cover Removal

Abstract This paper describes the results from a set of numerical experiments which stimulate the effect of a large-scale removal of snow cover in middle and high latitudes during the early spring season. This is done through use of a simplified general circulation model with a limited computational domain and idealized geography. It is found that removal of snow cover reduces the water available to the soil through snowmelt and decreases soil moisture in this region during the following seasons. Furthermore, it also reduces surface albedo in this region and increases absorption of insolation by the ground surface. This, in turn, heats the ground surface and allows more evaporation to occur. However, the change of evaporation is relatively small owing to the low values of surface temperature in high latitudes. Therefore, the negative anomaly of soil moisture induced initially by the removal of snow cover persists for the entire spring and summer seasons. The removal of snow cover also affects the thermal .
Influence de l'altitude, de l'exposition et du climat sur la croissance du pin à crochets ( Pinus uncinata Ram. ) en Cerdagne (Pyrénées orientales françaises)

A dendroecological study was carried out on mountain Pine ( Pinus uncinata Ram. ) in the French Cerdagne (Pyrenees Orientales). It permits to analyze the influence of three environmental factors: the altitude, the exposure and the climate. 175 dominant trees were sampled between 1780 and 2120 meters on north and south slopes. At the same altitude, the pines on north facing slope are four meters higher than those growing on south slope. However, a detailed analysis of 12874 tree-rings demonstrates that the radial growth is faster on the south slope. On such exposure, the basal area of the hundred years old trees increases 43 % higher than on north slope. Both forests show a similar high mean sensitivity. However, slight differences appear on the climatical response. The rainfall plays a more important part on south exposure, whereas the snow reduces the growth on north slopes. Moreover, the influence of the temperatures is greater than those of the precipitations. Warm spring temperatures are more efficient in the South, while the North is more influenced by the temperatures in autumn.
Microbiology and Vegetation of Micro-oases and Polar Desert, Haughton Impact Crater, Devon Island, Nunavut, Canada

The input of nutrients into arctic polar deserts, aided by some physical processes, can result in localized areas of high biological productivity—“micro-oases. ” We examined the vegetation cover, and microbial and nematode abundance in the polar desert and in 38 micro-oases at the Haughton impact crater, Devon Island, Arctic Canada. Our sites were split between the alluvial terraces along the banks of the Haughton River and the breccia deposits resulting from the asteroid or comet impact 22 Myr ago that flank the alluvial terraces. The alluvial terraces have a vegetation cover that ranges from 2 to 11% depending on substrate and water availability with a species richness of 5 in most locations. The vegetation cover on the breccia is much lower, between 0.02 and 3% depending on water availability. The micro-oases on both substrates support between 2 and 98% cover, but they are smaller and more sparsely distributed than similar features found in the Truelove Lowland, Devon Island, and on Bathurst Island. Microbial and nematode numbers were an order of magnitude greater inside the micro-oases compared to outside. Micro-oases are often dominated by a particular species, resulting in well-defined groups of micro-oases that were separated by TWINSPAN analysis. The micro-oases at Haughton Crater provide insights into the process of colonization of a substrate resulting from an asteroid or comet impact and the unique biological characteristics of such substrates.
Meteorlogical impact of replacing native perennial vegetation with annual agricultural species

Following the clearing of native perennial vegetation for agriculture based on winter growing annual species, the surface characteristics of south-western Australia have been significantly altered. Analysis of the annual variation of these characteristics based on satellite data and a one-dimensional boundary layer model suggests that convective mixing over the cleared land is no longer able to reach the lifting condensation level for a significant period of the year. This implies a decrease in convective cloud formation and a reduction in the convective enhancement of rainfall.