Miracle-dz/UniFAR-FTUs huggingface dataset:
Holocene climate variations at the entrance to a warm Arctic fjord: evidence from Kongsfjorden trough, Svalbard

Abstract The North Atlantic Current transports warm and salty water into the Nordic Seas and continues northwards into the Arctic Ocean as the West Spitsbergen Current. This current flows along the west coast of the Svalbard archipelago and into the fjords and troughs on the Svalbard shelf. We have investigated a core (NP05-11-21GC) from the Kongsfjorden trough, which spans the last 12 ka. The core site presently experiences seasonal inflow of Atlantic Water masses, and may therefore provide a record of past variations in Atlantic Water inflow to the Arctic. Lithological analysis and benthic foraminifera have been used to reconstruct the palaeoceanographic development in the area. The results show that cold and harsh conditions prevailed during the late part of the Younger Dryas and that the site was in proximity to glaciers. After 11.8 ka BP the first influence of Atlantic Water is seen in the fauna. This was followed by changes in glacial activity at 11.5 ka BP. During the period 11.5–10.6 ka BP the fauna indicate increased influence of Atlantic Water and the final deglaciation of the fjord after the Younger Dryas period. These initial ameliorated conditions were interrupted by a 250-year long cooling starting at 11.3 ka BP, corresponding to the Preboreal Oscillation. After 10.6 ka BP a marked change from an ice proximal to ice distal environment occurred accompanied by the strong influence of Atlantic Water masses. In the Mid-Holocene at 7 ka BP, the influence of Atlantic Water diminished but no sign of an immediate response of the glaciers to this are found in the core. The evidence suggests that intensification of glacial activity started as late as c. 3.5 ka BP. Comparing the core from Kongsfjorden trough with two shelf records from Svalbard generally shows similar faunal development although some differences exist. These are assumed to be related to the distance of each record to the position of the Arctic front.
Parameter identification and uncertainty analysis for simulating streamflow in a river basin of Eastern India

Uncertainty is inherent in modelling studies. However, the quantification of uncertainties associated with a model is a challenging task, and hence, such studies are somewhat limited. As distributed or semi‐distributed hydrological models are being increasingly used these days to simulate hydrological processes, it is vital that these models should be equipped with robust calibration and uncertainty analysis techniques. The goal of the present study was to calibrate and validate the Soil and Water Assessment Tool (SWAT) model for simulating streamflow in a river basin of Eastern India, and to evaluate the performance of salient optimization techniques in quantifying uncertainties. The SWAT model for the study basin was developed and calibrated using Parameter Solution (ParaSol), Sequential Uncertainty Fitting Algorithm (SUFI‐2) and Generalized Likelihood Uncertainty Estimation (GLUE) optimization techniques. The daily observed streamflow data from 1998 to 2003 were used for model calibration, and those for 2004–2005 were used for model validation. Modelling results indicated that all the three techniques invariably yield better results for the monthly time step than for the daily time step during both calibration and validation. The model performances for the daily streamflow simulation using ParaSol and SUFI‐2 during calibration are reasonably good with a Nash–Sutcliffe efficiency and mean absolute error (MAE) of 0.88 and 9.70 m3/s for ParaSol, and 0.86 and 10.07 m3/s for SUFI‐2, respectively. The simulation results of GLUE revealed that the model simulates daily streamflow during calibration with the highest accuracy in the case of GLUE (R2 = 0.88, MAE = 9.56 m3/s and root mean square error = 19.70 m3/s). The results of uncertainty analyses by SUFI‐2 and GLUE were compared in terms of parameter uncertainty. It was found that SUFI‐2 is capable of estimating uncertainties in complex hydrological models like SWAT, but it warrants sound knowledge of the parameters and their effects on the model output. On the other hand, GLUE predicts more reliable uncertainty ranges (R‐factor = 0.52 for daily calibration and 0.48 for validation) compared to SUFI‐2 (R‐factor = 0.59 for daily calibration and 0.55 for validation), though it is computationally demanding. Although both SUFI‐2 and GLUE appear to be promising techniques for the uncertainty analysis of modelling results, more and more studies in this direction are required under varying agro‐climatic conditions for assessing their generic capability. Copyright © 2015 John Wiley & Sons, Ltd.
The Soil Management Assessment Framework

Erosion rates and annual soil loss tolerance (T) values in evaluations of soil management practices have served as focal points for soil quality (SQ) research and assessment programs for decades. Our objective is to enhance and extend current soil assessment efforts by presenting a framework for assessing the impact of soil management practices on soil function. The tool consists of three steps: indicator selection, indicator interpretation, and integration into an index. The tool's framework design allows researchers to continually update and refine the interpretations for many soils, climates, and land use practices. The tool was demonstrated using data from case studies in Georgia, Iowa, California, and the Pacific Northwest (WA, ID, OR). Using an expert system of decision rules as an indicator selection step successfully identified indicators for the minimum data set (MDS) in the case study data sets. In the indicator interpretation step, observed indicator data were transformed into unitless scores based on site-specific algorithmic relationships to soil function. The scored data resulted in scientifically defensible and statistically different treatment means in the four case studies. The efficacy of the indicator interpretation step was evaluated with stepwise regressions using scored and observed indicators as independent variables and endpoint data as iterative dependent variables. Scored indicators usually had coefficients of determination (R 2 ) that were similar or greater than those of the observed indicator values. In some cases, the R 2 values for indicators and endpoint regressions were higher when examined for individual treatments rather than the entire data set. This study demonstrates significant progress toward development of a SQ assessment framework for adaptive soil resource management or monitoring that is transferable to a variety of climates, soil types, and soil management systems.
Paleolimnology and the Frontiers of Biogeography

For almost a century biogeographers have used paleoecological methods, including tree-ring, pollen, macrofossil, and charcoal analysis, to reconstruct climate and environmental conditions for the late Quaternary, but paleolimnological proxies and approaches provide new opportunities for biogeographers. In the last two decades, paleolimnology has grown rapidly as a result of several technical advancements: (1) the development of new proxies, (2) improved coring, sampling, and dating techniques that provide finer temporal resolution, and (3) more sophisticated statistical techniques and greater computing power, which allow for enhanced quantitative calibration of climate and environmental signals from paleolimnological proxies. These advances have led to a plethora of research projects, many using novel approaches, on climate change, anthropogenic impacts, conservation and restoration, aquatic/terrestrial links, resource management, succession, biodiversity, and introduced species. Paleolimnologists are working at the frontiers of biogeographical research, particularly contributing to research on climate change, biogeochemical cycles, and anthropogenic impacts on Earth systems.
Local rates of ice-sheet thickness change in Greenland

Abstract The rate of ice-sheet thickness change is calculated for 10 sites in Greenland by comparing measured values of ice vertical velocity and snow-accumulation rate. Vertical velocities are derived from repeat surveys of markers using precision global positioning system techniques, and accumulation rates are determined from stratigraphic analysis of firn cores. the results apply to time-scales covered by the firn-core records, which in most cases are a few decades. A spectrum of thickness-change rates is obtained, ranging from substantial thinning to slow thickening. the sites where ice-sheet thinning is indicated are located near the ice-sheet margin or in outlet glacier catchments. Interior and high-elevation sites are predominantly in balance or thickening slowly. Uncertainties in the rates of thickness change are dominated by errors in the determination of accumulation rates. the results of this work are broadly comparable with regional estimates of mass balance obtained from the analysis of catchment input vs discharge.
Formation of algal bloom in the northern Arabian Sea deep waters during January–March: a study using pooled in situ and satellite data

The formation of winter bloom (January–March) was studied in deep waters of the northeastern Arabian Sea (NAS) during 2003 and 2004. Six ship cruises were undertaken at different phases of the bloom to examine its formation. Along with physical and biological observations, optical parameters including profiles of upwelling and downwelling irradiance were collected using a Satlantic underwater radiometer and photosynthetically active radiation (PAR) was calculated using prosoft software. Satellite data sets for chlorophyll concentration, aerosol optical depth (AOD), PAR from the Oceansat‐I Ocean Colour Monitor (OCM), and sea winds vectors from the QuikSCAT scatterometer were also used to study the winter algal bloom formation. This study attempts to explain the probable mechanisms that activate the bloom and its dynamics, particularly those due to the influence of wind. The study also presents an intercomparison of relevant parameters during different phases of the event, from the late winter to early spring intermonsoon season. The causes of winter bloom reported by other investigators have been verified with the use of satellite data. An additional observation was attempted that strengthened the explanation of convective mixing and resulting intensification of the bloom. The higher wind speed in February–March 2003 compared to that in 2004 caused a higher aerosol concentration in the overlying atmosphere, thus leading to reduced shortwave solar radiation and PAR over the surface in 2003. This caused a cooling effect in the NAS deep waters. This cooling is thought to be supplementary to the already reported winter cooling, and to cooling due to evaporation. As a result, a substantial increase in surface seawater density was observed, consequently enhancing convective action due to densification and nutrient concentration. The result is that the bloom was homogeneous in space and had a larger concentration during March 2003 than March 2004.
Origin and distribution of different types of sinkholes in the plain areas of Southern Italy

Sinkholes constitute a significant risk in many karst areas, and may even threat human safety. Collapse sinkholes that occur catastrophically without showing premonitory signs may result in severe economic losses and casualties. In the last years, research on sinkholes and related detrimental effects has significantly increased in Italy, in the aftermath of remarkable events. Aimed at analysing the peculiar conditions which lead to sinkhole occurrence in Southern Italy, a set of cases in the plain areas of Campania, Apulia and Calabria is discussed. The considered regions show a wide variety of environmental conditions. In Campania, the plains are underlain by alluvial deposits with intercalations of volcaniclastic sediments. Sinkholes are generally located along the Tyrrhenian margin of the carbonate massifs or within intramontane Apennine basins. In Apulia, a flat and elongated peninsula, most of the cases occur on calcarenites overlying limestone bedrock along the coast. In Calabria, one of the most seismogenic Italian regions, the surveyed cases seem to be attributable mainly to earthquake-induced liquefaction. The article provides a first glance on the variety of sinkholes in the plain areas of Southern Italy, to highlight the possibility of further subsidence events in the considered regions, as well as in other comparable areas of the country.
Development of a small portable eyesafe unattended scanning lidar for analysis of the structural and optical properties of tropospheric aerosols

Structural and optical properties of aerosols and clouds can be retrieved by active remote sensing systems, such as lidars. Such parameters are of importance in the study of dynamics and radiation budget of the atmosphere. In that respect, a small, portable, eyesafe, unattended, elastic-backscatter lidar is being developed at Cimel Electronique, in collaboration with CNRS. It sues a compact, low-energy laser in the visible. The detection is made by a high-gain, high-speed PMT, and a single electronic card for fast acquisition. The aim of the system is also to be tunable to various pointing angles. A variational method was developed to make use of the multiangle measurements and tested on data collected during the INDOEX campaign in March 1999. The optical thickness and backscatter coefficient profiles were retrieved up to 1 km with a total uncertainty of 18 percent. The system has been assembled and first measurements have been made beginning of 2000 for comparison with the theoretical predictions. The system has shown it was satisfactory and the signal profiles obtained are in agreement with the ones simulated with the system parameters.
A Robust and Constrained Multi-Agent Reinforcement Learning Electric Vehicle Rebalancing Method in AMoD Systems

Electric vehicles (EVs) play critical roles in autonomous mobility-on-demand (AMoD) systems, but their unique charging patterns increase the model uncertainties in AMoD systems (e.g. state transition probability). Since there usually exists a mismatch between the training and test/true environments, incorporating model uncertainty into system design is of critical importance in real-world applications. However, model uncertainties have not been considered explicitly in EV AMoD system rebalancing by existing literature yet, and the coexistence of model uncertainties and constraints that the decision should satisfy makes the problem even more challenging. In this work, we design a robust and constrained multi-agent reinforcement learning (MARL) framework with state transition kernel uncertainty for EV AMoD systems. We then propose a robust and constrained MARL algorithm (ROCOMA) with robust natural policy gradients (RNPG) that trains a robust EV rebalancing policy to balance the supply-demand ratio and the charging utilization rate across the city under model uncertainty. Experiments show that the ROCOMA can learn an effective and robust rebalancing policy. It outperforms non-robust MARL methods in the presence of model uncertainties. It increases the system fairness by 19.6% and decreases the rebalancing costs by 75.8%.
Studies on the determination of swelling properties of soils from suction measurements

Expansive soils exhibit significantly high volumetric deformations and hence, pose a serious threat to stability of structures and foundations. As such, determination of their swelling properties (viz., swelling potential and swelling pressure) becomes essential. Earlier researchers have developed various experimental techniques, and empirical relationships based on the results obtained from these investigations, for determining swelling characteristics of these soils. However, although these techniques help in direct estimation of the swelling properties of soils, the instrumentation is quite cumbersome and time consuming. This limitation can be overcome by measuring soil suction, which would also yield its swelling characteristics, though indirectly, but quite rapidly and easily. To demonstrate the utility and ease of application of this methodology, attempts were made in the present study to establish swelling properties of expansive soils from their suction measurements. Details of the methodology ado.
Long-Term Variations of the External and Internal Components of the Earth's Magnetic Field

The present study applies classical techniques of time series analysis to the separation of the external and internal signals from the geomagnetic field. We first differentiate the data with respect to time in order to get rid of the large secular variation over the long time span considered (up to 100 years). Next we filter the resulting data to eliminate short-period components of the magnetic signals. We then proceed to identify the external signal by comparing the long-term variations of the processed components of the geomagnetic field, as measured at different European observatories, with the long-term variations of geomagnetic indices devised to characterize the fields from external sources. Finally, we remove the identified external signal from the geomagnetic field series and get a satisfactory estimate of the internal signal. This procedure is facilitated by the different behaviors of the two signals over the considered time span. The external signal is inherently of recurrent nature linked to solar-terrestrial interaction; it oscillates around zero with a maximum amplitude of about 5 nT/yr. The internal signal, on the other hand, displays the characteristics of a secular trend, combining sustained monotonous behavior over periods of several decades with sudden slope variations and reversals; the total range of this internal secular signal is of the order of 50 nT/yr, far larger than any external contribution. Using the 1883–1983 magnetic series at Chambon-la-Foret, the 1890–1983 series at Niemegk, and shorter series at the United Kingdom observatories of Eskdalemuir and Hartland, we have been able to get a coherent overall picture of the secular variation as measured in Europe. For instance, the first-order time derivative of the Y (east) component essentially displays an increase in two steps from 1900 to 1925, a monotonous decrease from 1925 to 1969 with a regular steplike substructure, and a rapid increase since 1969, followed by a marked reversal of slope in 1979. These results emphasize the internal origin of the 1969 jerk and single out, in Europe, a 1979 event of opposite sign, these two features being quite reminiscent of the behavior of the secular variation during the first quarter of the century.
The relation between interannual storage and frequency of droughts, with particular reference to the Pantanal Wetland of South America

A large volume of natural storage within a drainage basin has a marked effect on its regime of hydrologic extremes. In this paper, the carry‐over effects from one year to the next that result from large interannual storage are quantified for the Ladário gauging site below the Pantanal, the world's largest wetland, in the drainage basin of the River Paraguay. The presence of carry‐over effects introduces correlation between extremes in successive years, with the consequence that commonly used methods for calculating the frequencies of extreme events, all of which assume that values in successive years are statistically independent, are no longer appropriate. When serial correlation between annual flood peaks at Ladário is allowed for, the estimated mean length of longest drought period in a 100‐year period is extended by two years. The possibility that other factors contribute to the serial correlation in Ladário flood peaks is considered: no evidence was found of correlation with ENSO events as defined in the literature.
Characterization of aerosols over ocean from POLDER/ADEOS‐1

POLDER (POLarization and Directionality of the Earth's Reflectance) is a French instrument, launched in August 1996 onboard the Japanese sun‐synchronous ADvanced Earth Satellite System (ADEOS). Data were acquired until the loss of the platform June 30th 1997. This paper describes information on the global distribution of tropospheric aerosol over the ocean derived from the POLDER instrument. The aerosol remote sensing algorithm yields the aerosol optical thickness at 0.865 µm, τ and the Angström exponent, α, which allows the retrieval the aerosol sizes. Monthly synthesis of the global aerosol characteristics over the ocean are presented and described here for three months: November 1996, February, and May 1997. The major and most persistent feature is the Saharan dust outbreaks off West Africa. Biomass burning aerosols are observed during May off the western Mexican Coast and during November in Madagascar. Asian, Indonesian and eastern US pollution are also observed. For some of these areas, statistical distributions of τ and α and their spatial variability are discussed.
Glacier characteristics and sediment transfer system of Longyearbreen and Larsbreen, western Spitsbergen

Two small high-Arctic glaciers (Longyearbreen and Larsbreen) on Svalbard (78°N 15°E) were studied with respect to glaciological and hydrological characteristics. Fieldwork during the melting season of 1993 and 1994 was coupled with digital map analysis based on high-resolution digital elevation models (DEM) to reveal the dynamics and temperature regime of small glaciers in a high-Arctic environment, and its relationship to the material transport and sedimentation of these glaciers. The study showed Longyearbreen and Larsbreen to be low activity glaciers, cold-based with temperate patches, and thus having a low potential of basal erosion. The transport of ions and suspended solids in the glacial meltwater implies storage of material in and around the glacier which comes into contact with the meltwater. The study suggests that small Arctic glaciers couple the slope system with the fluvial system and therefore build a highly effective denudation system. Small polythermal glaciers are therefore important in understanding Pleistocene and Holocene landform development in cold regions.
On the subtropical frontal zone north of Hawaii during winter

Abstract Oceanic fronts in the subtropical frontal zone north of Hawaii are investigated and related to atmospheric forcing. Particular attention is paid to the winter of 1974 when a detailed study was made of the thermohaline structure aboard the R.V. Thomas G. Thompson. In that winter, well-defined fronts occurred at 34, 31 and 28°N. In the upper 100 m, these fronts are nearly vertical and are characterized by temperature, salinity and sound velocity gradients of up to 2°C (27 km)−1, 0.3‰ (27 km)−1 and 12 m s−1 (27 km)−1, respectively. Horizontal density gradients across the northern two fronts are small because of compensating horizontal temperature and salinity gradients. A thin layer of increased stability is encountered between 100 and 125 m. Below this layer, there are prominent lateral intrusions of cool and low-salinity subsurface water under warmer and higher salinity surface water, at latitudes north of 31°N and longitudes east of 155°W. The 0/1500 db dynamic height topography bears no similari.