Miracle-dz/UniFAR-FTUs huggingface dataset:
Timing, equilibrium-line altitudes and climatic implications of two early-Holocene glacier readvances during the Erdalen Event at Jostedalsbreen, western Norway

Following the Younger Dryas, the first evidence of glacial activity in southern Norway in response to climatic change occurred during the early Holocene, when terminal moraines from the Erdalen Event formed beyond the position of later ‘Little Ice Age’ moraines. In front of present outlet glaciers on both sides of the Jostedalsbreen ice cap, sets of pre-‘Little Ice Age’ marginal moraines have been morphostratigraphically corre lated with the Erdalen Event. The lithostratigraphy in a peat bog at Hellemyrane in Jostedalen, western Norway, provides firm evidence for a two-phase Erdalen Event associated with two glacier readvances of Nigardsbreen at the Preboreal/Boreal transition. Radiocarbon dates from the peat bog give age estimates for the two phases: the first Erdalen Event readvance took place between 10 100 and 10 050 cal. BP, while the second occurred close to 9700 cal. BP. The lowering of the equilibrium-line altitude (ELA) during these readvances is estimated using the ‘Little Ice Age’ ratio (LR) approach to be about 230 m and 215 m, respectively. The first readvance is attributed to an increase in winter precipitation, while the second readvance may have been primarily caused by a marked drop in summer temperature which reactivated already existing ice masses.
Arctic Climate Change as Manifest in Cyclone Behavior

Abstract The Arctic region has exhibited dramatic changes in recent times. Many of these are intimately tied up with synoptic activity, but little research has been undertaken on how the characteristics of Arctic cyclones have changed. This paper presents a comprehensive analysis of Arctic (here defined as the domain north of 70°N) cyclones diagnosed with the Melbourne University cyclone tracking scheme applied to the 40-yr ECMWF Re-Analysis (ERA-40) and the NCEP–NCAR (NCEP1) and NCEP–Department of Energy (DOE) Atmospheric Model Intercomparison Project (AMIP)-II (NCEP2) reanalysis sets (the last two extending to the end of 2006). A wide variety of cyclone characteristics is presented as befits these complex features. In winter the highest density of cyclones is found between Norway and Svalbard and to the east to the Barents and Kara Seas, and significant numbers are found in the central Arctic. In summer the greatest frequencies are found in the central Arctic. The total number of cyclones identified in .
Variability in tropical tropospheric ozone: Analysis with Global Ozone Monitoring Experiment observations and a global model

[1] Tropical tropospheric ozone columns (TTOCs) have been determined with a convective-cloud-differential (CCD) method, using ozone column and cloud measurements from the Global Ozone Monitoring Experiment (GOME) instrument. GOME cloud top pressures, derived with the Fast Retrieval Scheme for Clouds from the Oxygen A-band (FRESCO) method, indicate that most convective cloud top levels are between 300 and 500 hPa and do not extend to the tropical tropopause. The new GOME-CCD method takes this tropical transition layer below the tropopause into account and uses above-cloud and clear-sky ozone column measurements to derive a monthly mean TTOC below 200 hPa. Validation of the GOME-TTOCs with seven Southern Hemisphere Additional Ozonesondes (SHADOZ) sites shows good agreement, with an RMS difference of about 5 Dobson units. In the northern tropics the GOME-TTOC compares most of the time well with in situ measurements at Paramaribo (6°N, 55°W) and Abidjan (5°N, 4°W). Analysis of the GOME-TTOCs for 2000 and 2001, with the aid of the chemistry-transport model TM3, illustrates that the variability in the TTOC depends on a complex interaction of several processes, including biomass burning, lightning, and large-scale transport. The much larger extent of the South Atlantic TTOC maximum in September–October 2001, compared to September–October 2000, can be attributed to differences in large-scale transport. An exceptional situation in the northern tropics occurred during the biomass burning season December 2001 to January 2002, when there were almost no fires over northern Africa. This resulted in strongly reduced TTOCs over the Atlantic between the equator and 10°N.
Persistence of polar stratospheric clouds in the southern polar region

Observations of Antarctic polar stratospheric clouds (PSCs) were examined using the 1-micron aerosol extinction ratio data from the SAM II satellite experiment for the years 1979-1982 and 1984-1987. PSCs were sighted between 10 and 25 km and were usually first observed by mid-June. Clouds disappeared earlier at higher altitudes (late August near 24 km, in most cases) and later at lower altitudes (late September or October near 16 km). It was found that PSCs persisted longer in 1985 and 1987 at 18 km and were more frequently observed in September and October 1987 than the other years. Inference of likely PSC formation regions from National Meteorological Center temperature data indicated that clouds would begin forming in late May and usually disappear in September. This analysis confirmed the persistence of colder conditions during the spring of 1987.
Major active faults determine the location of the Tongonan geothermal field: Evidence provided by rock alteration and stable isotope geochemistry

Abstract The influence of major active faults on rock alteration and stable isotope geochemistry is described for the Tongonan geothermal field, Leyte, the Philippines. In the Pliocene, acid alteration with characteristic iron enrichment (3 g/100 g) and calcium depletion (2 g/100 g) occurred along a Riedel shear fault in the Malitbog sector, and initial minor acid alteration also occurred along a similar shear in the Mahiao sector. Later, sodium metasomatism (5 g/100 g) coincided with the highest aquifer chloride (10 000 mg/kg) as a result of dissociation of saline magmatic fluids discharging through the reservoir rocks in the Upper Mahiao. The incursion of magmatic fluids (possibly δD 35‰, δ18O +7‰) set up a vigorous convection cell of meteoric water, which focused around low‐angle (L) shears centered in the Sambaloran sector. Meteoric water (δD −35 to −40‰, δ18O −6 ± 1‰) depleted the reservoir in silica (6 g/100 g) and potassium (1–2 g/100 g). It also completely exchanged oxygen isotopes rapidly (within months) at high temperatures (300–400°C), and now does so continuously with fractured isotopically fresh or incompletely altered rock at small scales (centimeters or less) exposed by a 2 cm/year creep around the L shears to form a new component called geothermal water. Geothermal water mixes with meteoric water at lower temperatures (<300°C) to create the characteristic shift in δ18O of 6‰ at near constant δD (−35 ± 5‰). The 10‰ variation in δD is due to groundwater recharge derived from rain falling on steep terrain (5‰) and to enrichment of deuterium in boiling saline solutions (5‰); it is not due to two‐component mixing of meteoric with magmatic water. The low (∼1) isotopic water/rock (W/R) ratios calculated from oxygen isotopes in previously published reports are meaningless, because the water contains four components (predominantly geothermal and meteoric water; <10% magmatic and rock water). W/R ratios of up to 1500 calculated from spring and rock chemistry are more realistic and, with a flow rate of approximately 50 L/s through a 30 km3 reservoir, can account for the estimated 3 My age of the system.
Variations in Soil Carbon Stocks with Texture and Previous Landuse in North-western NSW, Australia

Australia’s land managers will need specific information about the best locations at which to sequester carbon if they are to take advantage of the recent Carbon Farming Initiative of the Australian Government under which carbon offsets can be created through sequestration of carbon in soil and trees. The literature indicates that soil texture and previous landuse are important determinants of soil carbon content. This paper describes the results of work to assess the current levels of soil carbon and the extent to which they vary with previous landuse and soil texture in the Namoi Catchment Management Authority in North West NSW, Australia. Soil samples were taken at 74 sites for determination of soil carbon concentration and stocks as well as soil texture and landuse in the last 10 years. There was wide variation between sites in soil carbon concentration and stocks which were greatest in those soils which had not been disturbed by cultivation and in soils with higher clay content. Thus, the greatest potential for carbon sequestration is in soils with the lowest carbon concentration, those which have been previously disturbed, and with higher clay content. Maintaining any increased carbon concentration will depend on minimizing disturbance, increased carbon input and minimizing loss of carbon through soil erosion. As these factors all vary significantly on a regional and landscape basis it will be important for land managers to have access to information which allows them to choose the sites at which potential for sequestration of soil carbon is greatest.
Nanoprobe crystallographic orientation studies of isolated shield elements of the coccolithophore species Emiliania huxleyi

Coccolithophore algae produce elaborately structured skeletons composed of sub-micrometer-scale calcite crystals. In order to understand calcite crystallization and assembly in a coccosphere with nanoscale resolution, the crystal orientation and interdigitation of the structural units were investigated by transmission electron microscopy imaging, selected-area and nano-probe electron diffraction. Focused ion beam sectioning of coccoliths of the coccolithophore species Emiliania huxleyi is used to obtain target-prepared specimens in suitable orientation. We were able to detect and analyze the V-unit, which is overgrown by the R-unit. For the V-unit the 001 direction points perpendicular to the coccolith plane while the 110 axis is tangential to the coccolith ring. The R-unit c-axis is parallel and the b-axis is perpendicular to the coccolith plane, thus confirming the R- and V-model which was based on scanning electron microscopy and optical microscopy. Furthermore we show that the distal- and the proximal shield element of an individual R-unit of a single segment are tilted by 4 degrees +/- 1 degrees with respect to each other. This orientation change is required to obtain the flat domed character of the coccoliths, which is necessary to form the coccosphere. The orientation change between the distal- and the proximal shield element appears continuous.
Experimental Study on the Anisotropic Hydraulic Conductivity of a Sandstone–Mudstone Particle Mixture

AbstractThis study focuses on the anisotropic hydraulic conductivity of a sandstone–mudstone particle mixture. Permeameter tests were performed in the laboratory. The effects of the mixture’s dry bulk density and mudstone particle content on its anisotropic hydraulic conductivity were investigated accordingly. Both the horizontal and vertical hydraulic conductivities were compared based on the calculation results from empirical grain-size formulas and tests. The best predictive formula for the hydraulic conductivities was found to be the Terzaghi empirical formula. It was found that the average horizontal hydraulic conductivity is about 2.0 times more than that of the vertical one. The anisotropy ratio initially increases and then decreases with the increase of the mudstone particle content by weight. A maximum ratio of 2.946 was obtained when the mudstone particle content reached about 60% by weight.
Spatial Variability in In Situ Aerobic Respiration and Denitrification Rates in a Petroleum‐Contaminated Aquifer

An extensive series of single‐well, push‐pull tests was performed to quantify horizontal and vertical spatial variability in aerobic respiration and denitrification rates in a petroleum‐contaminated aquifer. The results indicated rapid consumption of injected O2 or NO3− in shallow and deep test intervals across a large portion of the site. Computed first‐order rate coefficients for aerobic respiration ranged from 0.15 to 1.69 h−1 in the shallow test interval, and from 0.08 to 0.83 h−1 in the deep test interval. The largest aerobic respiration rates occurred on the upgradient edge of the contaminant plume where concentrations of petroleum hydrocarbons and dissolved O2 were relatively high. Computed first‐order rate coefficients for denitrification ranged from 0.09 to 0.42 h−1 in the shallow test interval, and from 0.11 to 0.28 h−1 in the deep test interval. The largest denitrification rates occurred on the downgradient edge of the plume where hydrocarbon concentrations were relatively high but dissolved oxygen concentrations were small. The rates reported here represent maximal rates of aerobic respiration and denitrification, as supported by high concentrations of electron acceptors in the injected test solutions. Production of dissolved CO2 during aerobic respiration and denitrification tests provided evidence that O2 and NO3− consumption was largely due to microbial activity. Additional evidence for microbial NO3− consumption was provided by reduced rates of NO3−consumption when dissolved O2 was injected with NO3−, and by increased N2O production when C2H2 was injected with NO3−.
Global carbon assimilation system using a local ensemble Kalman filter with multiple ecosystem models

In this paper, a global carbon assimilation system (GCAS) is developed for optimizing the global land surface carbon flux at 1° resolution using multiple ecosystem models. In GCAS, three ecosystem models, Boreal Ecosystem Productivity Simulator, Carnegie‐Ames‐Stanford Approach, and Community Atmosphere Biosphere Land Exchange, produce the prior fluxes, and an atmospheric transport model, Model for OZone And Related chemical Tracers, is used to calculate atmospheric CO2 concentrations resulting from these prior fluxes. A local ensemble Kalman filter is developed to assimilate atmospheric CO2 data observed at 92 stations to optimize the carbon flux for six land regions, and the Bayesian model averaging method is implemented in GCAS to calculate the weighted average of the optimized fluxes based on individual ecosystem models. The weights for the models are found according to the closeness of their forecasted CO2 concentration to observation. Results of this study show that the model weights vary in time and space, allowing for an optimum utilization of different strengths of different ecosystem models. It is also demonstrated that spatial localization is an effective technique to avoid spurious optimization results for regions that are not well constrained by the atmospheric data. Based on the multimodel optimized flux from GCAS, we found that the average global terrestrial carbon sink over the 2002–2008 period is 2.97 ± 1.1 PgC yr−1, and the sinks are 0.88 ± 0.52, 0.27 ± 0.33, 0.67 ± 0.39, 0.90 ± 0.68, 0.21 ± 0.31, and 0.04 ± 0.08 PgC yr−1 for the North America, South America, Africa, Eurasia, Tropical Asia, and Australia, respectively. This multimodel GCAS can be used to improve global carbon cycle estimation.
A quantitative palynostratigraphy of the Miocene Manuherikia Group, New Zealand

A quantitative palynostratigraphy is presented for the Manuherikia Group, New Zealand Six stratigraphic sections were studied from the northern Manuherikia basin where the relative proportions of six pollen taxa were compared Nothofagus ‘brassu type’, Nothofagus ‘fusca type’, Casuannaceae, Myrtaceae, Arecaceae, Asteraceae, and Chenopodiaceae A consistent order of dominance is apparent and zone boundaries are erected based on dominance of the latter five taxa over that of Nothofagus ‘brassu type’ Four new zones are proposed the Nothofagus ‘brassu type’ Zone, the Arecaceae‐Myrtaceae Zone, the Casuannaceae Zone, and the Asteraceae‐Chenopodiaceae Zone The latter is essentially a redefinition of the Chenopodipolhs chenopodiaceoides Zone of Mildenhall and Pocknall Correlation with the International time scale is attempted the N ‘brassu type’ Zone is Early Miocene, while the base of the Casuannaceae Zone or the Asteraceae‐Chenopodiaceae Zone may correlate with major global cooling recognised at approximately 14 Ma
Influence of cloud properties on satellite total ozone observations

[1] Clouds represent one of the most important atmospheric factors that can significantly reduce the accuracy of satellite total ozone column (TOC) data. The influence of clouds on the TOC retrieval from satellites is usually assessed by means of theoretical studies using radiative transfer models. In contrast, few experimental results were found in the literature about the effects of the cloud properties on the differences between satellite TOC data and accurate ground-based measurements. This paper is focused on the study of the joined influence of the cloud properties under different satellite viewing conditions on the TOC data derived from four satellite instruments (GOME/ERS-2, GOME-2/MetOp-A, SCIAMACHY/Envisat, and OMI/Aura) using as reference five Brewer spectrophotometers in the Iberian Peninsula. Satellite TOC data under cloud-free and cloudy conditions are compared with ground-based measurements for the time period 2006 to 2009. The TOC products derived using the Differential Optical Absorption Spectroscopy (DOAS) technique, GOME, GOME-2, SCIAMACHY and OMI-DOAS, show a notable underestimation for cloudy conditions that clearly decreases with increasing Sun zenith angles (SZA). For those DOAS TOC products, the viewing zenith angle (VZA) also shows a significant influence on the satellite-Brewer differences, mainly for the west pixels and cloud-free conditions. The OMI-TOMS TOC product under cloud-free and cloudy conditions presents a more stable pattern for both SZA and VZA values, but this result must be interpreted carefully because OMI-TOMS classifies an unrealistic high number of scenes as cloud-free (∼57% of all). The analysis of the relative TOC differences as a function of the satellite cloud fraction indicates that SCIAMACHY and OMI-DOAS products have a large difference between the curves corresponding to low and high SZA cases. The two GOME algorithms and, mainly, the OMI-TOMS algorithm present a remarkable stability for all cloud conditions.
Precursors to failure in rocks while undergoing anelastic deformations

Modeling of geological processes in the laboratory is often quite difficult. Stress accumulation prior to an earthquake occurs over a long time and is associated with large anelastic deformation. We have chosen pyrophyllite as a model material because of its large anelastic deformation (several percent) before brittle failure. Samples of pyrophyllite were stressed to failure in a biaxial press. Photography through transparent pistons, optical holography, microscopy, and sound velocity measurements were used as tools to study the processes leading to brittle failure. At about 50% of ultimate failure strength a zone of preferential deformation forms around the incipient fault, and the seismic velocities decrease perpendicular to the axis of maximum principal stress. At higher stress levels the intense deformation zone becomes very narrow and the velocities increase again before failure. En echelon cracks form in the most narrow part of the intense deformation zone and precede the formation of a macrocrack and a stress drop. The intense deformation zone remains very narrow in front of the macrocrack. Further en echelon crack formation within the intense deformation zone appears before a further advance of the macrocrack. The above observations, especially the velocity reversal before failure, are rate and mositure dependent. Theymore » were clearly detectable at a strain rate of 3 x 10/sup -/8/s but barely noticeable at 5 x 10/sup -/7/s. « less
Role of solar wind dynamic pressure in driving ionospheric Joule heating

[1] We investigate the role of the solar wind dynamic pressure on the ionospheric dynamics both observationally and using a global MHD simulation. Using ACE solar wind observations we carry out a statistical superposed epoch analysis, in which we determine the ionospheric response, as characterized by the AE index, to solar wind pressure pulses identified from the ACE solar wind data. We find that under steady southward interplanetary magnetic field the AE index increases 35% in 20 min following the pressure pulse but that no such reaction is observed under steady northward IMF. Second, we determine the ionospheric Joule heating in several events using a global MHD simulation GUMICS-4. We find that the solar wind dynamic pressure and the Joule heating are positively correlated. Finally, we discuss mechanisms linking the dynamic pressure to Joule heating. We find evidence that in the simulation, increasing dynamic pressure increases field-aligned currents, which then increases ionospheric Joule heating.
A Probable Fossil Glacier

Mining operations in Hurricane Basin, in the Silverton Quadrangle of Colorado, have disclosed the presence of a body of ice beneath rock-stream and landslide débris. The ice is believed to represent the remnant of a glacier, and the relations appear to confirm the suggestion of Cross and Howe that the rock débris buried small glaciers remaining in the cirques after the ice disappeared from the main valleys.
Correction of bottom influence in ocean colour satellite images of shallow water areas of the Baltic Sea

Ocean colour satellite measurements are mainly disturbed by the atmosphere, the sea surface and the sea bottom in shallow water areas. In such areas special features of bottom topography can be recognized in satellite images of the visible spectrum and the derived concentrations of water constituents are often misinterpreted. The influence of the sea bottom depends on the water depth, the transmission of the water column, the reflectance of the water, the reflectivity of the bottom materials and the used spectral channels of satellite sensors. The influence of the sea bottom on the spectral reflectance at the sea surface is discussed here on the basis of model computations. The calculations are realized for examples of shallow water areas of the Baltic Sea. Furthermore, a technique for the identification of sea bottom disturbed pixels in satellite images and for the elimination of bottom effects is presented. A linear regression analysis between the bottom depth and the spectral reflectance in the different satellite sensor channels is used in order to test the correlation between these two variables. If a relationship exists, the reflectances have to be corrected. This procedure and the elimination of the bottom influence will be explained for specific satellite systems.
Surface Rupture and Co‐seismic Displacement Produced by the Ms 8.0 Wenchuan Earthquake of May 12th, 2008, Sichuan, China: Eastwards Growth of the Qinghai‐Tibet Plateau

An earthquake of Ms 8 struck Wenchuan County, western Sichuan, China, on May 12th, 2008 and resulted in long surface ruptures (>300 km). The first‐hand observations about the surface ruptures produced by the earthquake in the worst‐hit areas of Yingxiu, Beichuan and Qingchuan, ascertained that the causative structure of the earthquake was in the central fault zones of the Longmenshan tectonic belt. Average co‐seismic vertical displacements along the individual fault of the Yingxiu‐Beichuan rupture zone reach 2.5‐4 m and the cumulative vertical displacements across the central and frontal Longmenshan fault belt is about 5–6 m. The surface rupture strength was reduced from north of Beichuan to Qingchuan County and shows 2–3 m dextral strike‐slip component. The Wenchuan thrust‐faulting earthquake is a manifestation of eastward growth of the Tibetan Plateau under the action of continuous convergence of the Indian and Eurasian continents.