Miracle-dz/UniFAR-FTUs huggingface dataset:
Large-Scale Precipitation Variability over Northwest China Inferred from Tree Rings

AbstractA preliminary study of a point-by-point spatial precipitation reconstruction for northwestern (NW) China is explored, based on a tree-ring network of 132 chronologies. Precipitation variations during the past ~200–400 yr (the common reconstruction period is from 1802 to 1990) are reconstructed for 26 stations in NW China from a nationwide 160-station dataset. The authors introduce a “search spatial correlation contour” method to locate candidate tree-ring predictors for the reconstruction data of a given climate station. Calibration and verification results indicate that most precipitation reconstruction models are acceptable, except for a few reconstructions (stations Hetian, Hami, Jiuquan, and Wuwei) with degraded quality. Additionally, the authors compare four spatial precipitation factors in the instrumental records and reconstructions derived from a rotated principal component analysis (RPCA). The northern and southern Xinjiang factors from the instrumental and reconstructed data agree well w.
Water Mass Transformation in the North Atlantic and Its Impact on the Meridional Circulation: Insights from an Ocean Model Forced by NCEP–NCAR Reanalysis Surface Fluxes

Decadal-scale climate variability in the North Atlantic thermohaline circulation is simulated using a sigma-coordinate primitive equation model, forced by NCEP–NCAR reanalysis surface forcing fields for the period from 1958 to 1997. Surface heat and freshwater flux are expressed in terms of surface thermal and haline density inputs, diagnosed by the model. Variability in surface density fluxes is closely correlated with the North Atlantic Oscillation and demonstrates differences with the original surface heat and freshwater fluxes. Leading modes of surface water mass transformation are considered in the T–S plane. They identify decadal-scale variability associated with the transformation of the Labrador Sea Waters and Subtropical Mode Waters. Analysis of the model responses to the surface forcing shows an immediate reaction of meridional heat transport to the wind stress curl, resulting in a decrease of meridional heat transport at 48°N and an increase in the subtropics. Delayed baroclinic responses to the surface heat forcing are identified at time lags of 3 and 7 yr. The 3-yr response is represented by an increase in the total meridional heat transport in subpolar latitudes and its simultaneous increase in the Tropics and midlatitudes. The 7-yr delayed response to the surface heat forcing is associated with the strengthening of meridional heat transport at all latitudes. However, 7-yr responses may be influenced by the self-correlation in the meridional heat transport and forcing function. Meridional overturning is largely responsible for the variability observed, demonstrating high correlation with meridional heat transport.
Seismic and drilling constraints on velocity structure and reflectivity near IODP Hole U1309D on the central dome of Atlantis Massif, Mid‐Atlantic Ridge 30°N

The seismic structure of the upper ∼1 km of the central dome of Atlantis Massif is investigated in the context of lithologies known from seafloor drilling and physical property measurements obtained within the borehole and on core samples. A new analysis of seafloor refraction data and multichannel reflection data acquired in the immediate vicinity of Integrated Ocean Drilling Program (IODP) Site U1309 was motivated by a discrepancy between initial seismic interpretations, which indicated mantle velocities at shallow depth, and the gabbroic sequence recovered by drilling. A new seismic velocity model is derived that is consistent with the full suite of geological and geophysical data in the central dome area; all of these data show that mafic intrusive rocks dominate the upper portion of the footwall of this oceanic core complex and that laterally extensive zones of ultramafic rocks are not required by the data. The origin of subseafloor reflectivity beneath the central dome was also considered. We find that seafloor scattering complicates the interpretation of multichannel seismic data acquired near Site U1309 but that detectable subsurface impedance contrasts do occur. Downhole variations in alteration may generate reflections observed from the upper kilometer of the central dome.
Mudanças florísticas e estruturais no cerrado sensu stricto ao longo de 27 anos (1985-2012) na Fazenda Água Limpa, Brasília, DF

Resumodas comunidades vegetais ao longo do tempo sao fundamentais para a predicao de suas trajetorias frente a disturbios, portanto, para sua conservacao. Dessa forma, este estudo objetivou avaliar a composicao floristica, riqueza, diversidade e estrutura da comunidade lenhosa em uma area de cerrado sensu stricto na Fazenda Agua Limpa, Brasilia, DF num periodo de 27 anos. Inventarios continuos foram conduzidos a cada tres anos em 19 parcelas permanentes de 1.000 m² (20 × 50 m) e, neste periodo, quatro eventos de fogo ocorreram no local. Os episodios de queimada nao contribuiram com mudancas significativas em niveis de riqueza e diversidade na comunidade lenhosa ao longo de todo o periodo de estudo. Ao contrario, tem contribuido para a estabilidade floristica e estrutural da comunidade, uma vez que a abundância e a densidade da comunidade se modificaram consideravelmente apos periodo longo de exclusao do fogo. A supressao do fogo por periodos mais longos do que os ocorridos podera conduzir a mudancas floristicas e estruturais importantes na comunidade estudada. Palavras-chave: dinâmica de comunidades, fogo, NMDS, vegetacao arborea.
Hot spring and geyser sinters: the integrated product of precipitation, replacement, and deposition

Complex ornate sinter deposits are found in many hot spring and geysers systems throughout the world, including those located in the Taupo Volcanic Zone on the North Island of New Zealand. Those sinters are formed of opal-A that replaced microbes, opal-A precipitated as cement, accessory minerals (e.g., kaolinite, jarosite, calcite), biological detritus (e.g., leaves, wood, pollen grains), and lithic detritus. The opal-A is compositionally variable because of the amount of water (OH and H2O) and, in some cases, accessory elements (e.g., Au, Ag) bound into its structure. The composition and fabric of the siliceous sinter found at any locality reflect the relative balance among the processes of replacement, precipitation, and deposition. The microbes that inhabit these systems are of critical importance because they are commonly replaced by and (or) encrusted with opal-A. In many settings, copious amounts of opal-A are precipitated as cement around the frameworks of silicified filaments. The cementation pro.
A survey of blasting activity in the United States

Statistical information on chemical explosions is needed in seismology, to evaluate the practical difficulties in identifying this very common type of seismic source from other seismic sources such as small earthquakes and small nuclear explosions. We have obtained data on blasting activity from three different sources: (1) overview information from the U.S. Bureau of Mines (USBM) on the total amount of chemical explosives used in the United States during 1987, with breakdowns into different explosive types, and usage by different states; (2) overview information from the Mine Safety and Health Administration (MSHA) on the numbers of mines, of different types, in the United States; and (3) detailed information from a private company (Vibra-Tech Engineers, Inc.) on total shot size and size of charge per delay for 20,813 blasts carried out in 1987 at 532 locations. Our procedure has been to extrapolate the detailed information contained in the 1987 Vibra-Tech data for a limited number of states and thus to obtain estimates for the whole country on numbers of shots and their size distribution. The extrapolation is constrained by the data from USBM (numbers of shots, sizes) and the MSHA (locations). Blasting activity does not fluctuate greatly from year to year and 1987 was representative of current practice. We find that about 2.2 million metric tons of chemical explosive are used annually in the continental U.S., principally in mining for coal and metal ores. On a typical work day, there are roughly 30 explosions greater than 50 tons, including about one greater than 200 tons. There was one industrial explosion in 1987 at about 1400 tons. For shots between 1 ton and 100 tons, the cumulative distribution has a b-value near unity; that is, if N is the number of shots (per year) greater than or equal to W tons, N ∝ 10 − b log ⁡ W = W − b with b roughly equal to 1. This result is similar to the size distribution of earthquakes greater than magnitude mb, N ∝ 10 − b m b . Almost all chemical explosions above 1 ton are ripple-fired. The typical shot uses 20 to 50 separate delays.
A computer model for meandering rivers with multiple bed load sediment sizes: 2. Computer simulations

The theory for flow and sediment transport in a curved channel that was presented by Sun et al. [this issue], paper 1 of this two‐part study, was used to develop a computer model for meandering rivers with multiple sediment grain sizes. The model, which is based on the linear theory of Johannesson and Parker [1989] for meandering rivers, takes into account the effects of alternate bars. Therefore this is one of the first models that can be used to simulate bar‐bend interactions and their relationships with both the initial growth and the long‐term development of meandering rivers. Unlike the previous theoretical studies of Blondeaux and Seminara [1985] and Johannesson and Parker [1989], the results show that the initial growth of meandering rivers is controlled primarily by the curvature‐related instabilities, and the influence of alternate bars on the initial development of meander loops appears to be negligible. The simulations also show that under certain conditions, meandering rivers do evolve toward a “resonant” state. It appears that finite amplitude perturbations are needed to enhance the initial development of alternate bars in the channel in order for the river to develop toward a bar‐bend resonance state. The model includes the transport and sorting of sediment with a distribution of grain sizes. Heterogeneities in the sedimentary material deposited in the floodplain, as a result of meandering river migration, are realistically simulated.
Hotspots of vegetation-climate feedbacks under future greenhouse forcing in Europe

We performed simulations of future biophysical vegetation-climate feedbacks with a regional Earth System Model, RCA-GUESS, interactively coupling a regional climate model and a process-based model of vegetation dynamics and biogeochemistry. Simulated variations in leaf area index and in the relative coverage of evergreen forest, deciduous forest, and open land vegetation in response to simulated climate influence atmospheric state via variations in albedo, surface roughness, and the partitioning of the land-atmosphere heat flux into latent and sensible components. The model was applied on a similar to 50 x 50 km grid over Europe under a future climate scenario. Three potential "hot spots" of vegetation-climate feedbacks could be identified. In the Scandinavian Mountains, reduced albedo resulting from the snow-masking effect of forest expansion enhanced the winter warming trend. In central Europe, the stimulation of photosynthesis and plant growth by "CO2 fertilization" mitigated warming, through a negative evapotranspiration feedback associated with increased vegetation cover and leaf area index. In southern Europe, increased summer dryness restricted plant growth and survival, causing a positive warming feedback through reduced evapotranspiration. Our results suggest that vegetation-climate feedbacks over the European study area will be rather modest compared to the radiative forcing of increased global CO2 concentrations but may modify warming projections locally, regionally, and seasonally, compared with results from traditional "off-line" regional climate models lacking a representation of the relevant feedback mechanisms.
A global lightning location algorithm based on the electromagnetic signature in the Schumann resonance band

[1] A new improved algorithm has been developed to geolocate intense lightning flashes around the globe. The method uses ELF (extremely low frequency) radiation propagated in the Earth-ionosphere cavity to locate unusually intense lightning strokes. Two parameters are needed to locate the lightning discharge from a single station: bearing and source-observer distance (SOD). The bearing was obtained using the Poynting vector (E × H), while the SOD was obtained on the basis of the modeling of the electric and magnetic ELF spectra and the comparison with experimental data. To check the accuracy of our algorithm, we used primarily infrared cloud top temperature images of deep convective storms from geostationary satellites (METEOSAT, GOES, and GMS). Analysis of ELF data from our field station of 147 events gave an average source-observer distance error of 660 km (7.05%) and azimuth error of 1.9°. Of the 147 events, 72% had positive polarity, while the majority (59%) occurred over the oceans.
‘Tsunami third wave’ and the politics of disaster management in Sri Lanka

The paper compares the social and political consequences of two disasters that struck Sri Lanka 70 years apart, the 1934–1935 malaria epidemic that killed over 100,000 people and the tsunami of 26 December 2004. The main argument is that while the state and civil society responses to the malaria epidemic of 1930s in many ways led to the establishment and development of the Sri Lankan welfare state and the related outcomes, including rapid advances in quality of life particularly in the rural sector, the more elaborate and well-funded tsunami response driven by the international humanitarian industry failed to facilitate speedy recovery, failed to galvanize the peace process and even added to the vulnerability of some of the affected people due to the rapid exodus of many newly arrived INGOs before completing their humanitarian mission. While the relative failure of the tsunami response may be partly attributed to the persistent conflict between the Government of Sri Lanka and the Liberation Tigers of Tamil Eelaam (LTTE), it also exposes some of the key weaknesses of humanitarian aid in the modern world. A more historically grounded and conflict-sensitive approach is necessary along with greater coordination among agencies involved.
Localization of microbarom sources using the IMS infrasound network

[1] Multiyear continuous infrasound monitoring with the global International Monitoring System (IMS) demonstrates that microbaroms, generated by nonlinear interaction of opposing oceanic surface waves, are globally observed at equatorial, middle, and high latitudes. Direction of arrival of microbarom signals are systematically estimated at all IMS infrasound stations. Using a cross-bearing method, we perform a monthly localization of worldwide microbarom sources. At most stations, microbarom detections show clear seasonal trends, driven by stratospheric wind reversals and source effects. Five-year averaging of the detections provides global and statistical observations of seasonal source variations. Our microbarom source locations represent a first attempt to infer ocean swell characteristics from global and long-term measurements. We show that the monthly averaged source locations exhibit clear seasonal switching between the northern and southern hemispheres. Such an approach can help with evaluating the network detection capability, and provides new insights into quantitative relationships between infrasonic observables, atmospheric specifications, and ocean–atmosphere interactions.
Global carbonate accumulation from 145 Ma to Present (Cretaceous-Cenozoic): a new continental-scale analysis

Abstract Analysis of continental-scale lithostratigraphic data may facilitate an understanding of global sedimentary processes. The number of carbonate-bearing formations established in northern Eurasia (430 in total), northern Africa and Arabia (47 in total), and India (98 in total) is calculated per epochs for the last 145 Ma. The results show maxima in the Late Cretaceous, the Eocene, and the Miocene and minima in the Paleocene, the Oligocene, and the Pliocene. The Quaternary records are somewhat ambiguous. The similarity of the patterns established in the three regions argues for a single globalscale mechanism of carbonate accumulation. The noted patterns also coincide well with some modeled changes in the global amount of carbonates accumulated by epoch. Moreover, increases in the amount of carbonates in the Late Cretaceous and the Eocene, and a decrease in the Paleocene, reflect true changes in the accumulation rates. The global process of carbonate accumulation might have been controlled, at least,.
The influence of a lateral basin-slope on the depositional patterns of natural and experimental turbidity currents

Abstract Understanding topographic effects upon the depositional processes of turbidity currents and the resulting deposit characteristics is key to producing reliable depositional models for turbidity currents. In this study, the effect on depositional patterns of a lateral slope whose strike is parallel to the principal direction of flow is explored using field and experimental results. This type of basin topography is commonly found in confined turbidite systems. Field data from the Peïra Cava turbidite system of the Tertiary Alpine Foreland Basin (SE France) and experimental data show that a characteristic depositional pattern is produced by surge-type waning flows that interact with a lateral slope. This pattern comprises beds that thin (and fine in the field study) not only downstream but also markedly away from the lateral slope (Type I beds). In the Peïra Cava system, this pattern is also observed in average values of sandstone bed thickness, sandstone percentage and grain-size, derived from measured sections, demonstrating that the processes responsible for this pattern also control gross properties within this sheet system. The characteristic thinning-away-from-slope deposit geometry is interpreted as an effect of the lateral slope via its influence on spatial variations in flow properties and on the suspended load fallout rate (SLFR) from currents. Flow velocity non-uniformity cannot explain thinning into the basin because flow has a higher deceleration along streamlines away from the slope that should cause higher SLFR and thicker deposits away from the slope instead of close to the slope. A concentration non-uniformity mechanism is invoked that has the effect of maintaining relatively high flow concentrations and hence SLFR in medial and distal locations close to the slope. Experiments suggest that this may arise due to different rates of flow expansion on the obstructed and unobstructed sides of the current in proximal regions. Velocity non-uniformity can, however, explain the geometry of deposits that thicken away from slope. Beds of this type do occur occasionally in the Peïra Cava system (Type II beds). Flow velocity non-uniformity patterns have been used previously to successfully explain the spatial distributions of depositional facies of turbidity currents that have interacted with topography. The analysis in this study demonstrates that velocity non-uniformity, by itself, cannot explain depositional patterns in all basin settings. Future depositional models need to incorporate the effects of spatial changes in other flow properties, such as flow concentration, upon deposition to be able to predict turbidite facies in many different types of basin setting.
North Atlantic Subtropical Mode Water: A history of ocean‐atmosphere interaction 1961–2000

Water masses that ventilate intermediate ocean depth, such as the North Atlantic Subtropical Mode Water (NASTMW), play important roles in various aspects of climate, but their basic properties and space‐time variability need to be better quantified. Herein we examine the mean annual cycle and long‐term variability of NASTMW for the 40‐year period 1961–2000. Integrated NASTMW properties such as water mass volume, temperature, and heat content show a consistent annual cycle superimposed over a much larger interannual‐to‐decadal cycle that is strongly correlated to the North Atlantic Oscillation index. The 40‐year record clearly shows the ocean's ability to integrate atmospheric forcing over several years and to exhibit an interannual memory of wintertime forcing by the atmosphere.
MASSACHUSETTS INSTITUTE OF TECHNOLOGY ARTIFICIAL INTELLIGENCE LABORATORY and CENTER FOR BIOLOGICAL AND COMPUTATIONAL LEARNING DEPARTMENT OF BRAIN AND COGNITIVE SCIENCES

Sigmoid type belief networks, a class of probabilistic neural networks, provide a natural framework for compactly representing probabilistic information in a variety of unsupervised and supervised learning problems. Often the parameters used in these networks need to be learned from examples. Unfortunately, estimating the parameters via exact probabilistic calculations (i.e, the EM-algorithm) is intractable even for networks with fairly small numbers of hidden units. We propose to avoid the infeasibility of the E step by bounding likelihoods instead of computing them exactly. We introduce extended and complementary representations for these networks and show that the estimation of the network parameters can be made fast (reduced to quadratic optimization) by performing the estimation in either of the alternative domains. The complementary networks can be used for continuous density estimation as well. Copyright c Massachusetts Institute of Technology, 1996 In press: In Advances in Neural Information Processing Systems 8, MIT Press. This report describes research done at the Dept. of Brain and Cognitive Sciences, the Center for Biological and Computational Learning, and the Arti cial Intelligence Laboratory of the Massachusetts Institute of Technology. Support for CBCL is provided in part by a grant from the NSF (ASC{9217041). Support for the laboratory's arti cial intelligence research is provided in part by the Advanced Research Projects Agency of the Dept. of Defense. The authors were supported by a grant from the McDonnell-Pew Foundation, by a grant from Siemens Corporation, by a grant >from Daimler-Benz Systems Technology Research, and by a grant from the O ce of Naval Research. Michael I. Jordan is a NSF Presidential Young Investigator.
The mesopause region wind field over Central Europe in 2003 and comparison with other years

Using the D1 method in the LF range, monthly mean zonal and meridional winds in the mesosphere/lower thermosphere height range are measured continuously at Collm, Germany. The wind data are accompanied by reference height measurements since 1983, allowing the construction of an empirical long-term climatology of mean winds and tidal amplitudes and phases at 52N, 15E, which covers the height range of 80-110 km in winter, and about 83-107 km in summer. The climatology includes the time interval from 1983 to date, thus covering nearly two solar cycles. Vertical wind parameter profiles can also be constructed for individual years, so that from the time series interannual variability and long-term trends can be deduced. Here we present the results for 2003 in comparison with the climatological means.
Linear polarization measurements of a wheat canopy

Abstract The amount of linearly polarized light reflected by a wheat canopy was measured using a polarizing filter attached to a radiometer at two wavelengths (478 nm and 668 nm) and three view zenith angles (60°, 70°, 80°). Measurements were carried out in the anti-solar direction in the principal plane, with relative azimuth between Sun and view directions being 180°. It is found that the degree of polarization (DOP) and mean polarized radiance (R¯ Q ) between stages is statistically significant at view zenith angles of 70° and 80°, in the blue wavelength region. It is concluded that DOP and R¯ Q are better indicators of the onset of heading stage. Calculations of polarized reflectance using Fresnel reflection equations are also presented.