Miracle-dz/UniFAR-FTUs huggingface dataset:
Using JGOFS in situ and ocean color data to compare biogeochemical models and estimate their parameters in the subtropical North Atlantic Ocean

How well do biogeochemical data sets serve to decide among models and model parameter values? Data at 21N, 31W from the French JGOFS EUMELI cruises and the SeaWiFS ocean color sensor were used to estimate parameters for three very different models of biological nitrogen flux in a water column. The three models are (1) an NPZD (Nutrients, Phytoplankton, Zooplankton and Detritus) model (Oschlies et al., 2000), (2) a seven-component model with two pools of dissolved organic matter and detritus with different remineralization and sinking rates (Dadou et al., 2001) and (3) a model of nutrients and phytoplankton including aggregates (Kriest and Evans, 1999). Parameters of the three models are estimated using the same sets of data within the same one-dimensional physical framework. A combination of local and nonlocal optimization methods is used. It is not easy to decide among candidate models based on their fit to the data. Parameters that mean the same thing in the three models, like the half-saturation concentration for nitrate uptake, were estimated at not very different values in different models. The model with dissolved organic matter, based on its primary production and sediment flux data time evolutions, seems to exhibit the more reasonable annual behavior. Large seasonal changes in deep nitrate data suggest an unexpected role of lateral advection and may vitiate the 1-D approach even at the EUMELI oligotrophic site. The small number of sediment trap measurements are very powerful for constraining the biological nitrogen. Ocean color data did not add extra constraining power.
Near-field TEC response to the main shock of the 2008 Wenchuan earthquake

We have registered near-field TEC response to the Wenchuan earthquake on 12 May 2008, for the first time. We found that an intensive N-shape shock-acoustic wave with a plane waveform and with half-period of about 200 sec propagated south-eastward with a velocity of 600 m/s for distance about 1000 km. The wavefront of N-shaped disturbance was parallel with the earthquake rupture direction (from SW to NE). The main directional lobe of shock-acoustic wave emitter is directed southeastward, i.e. transversely to the rupture. We suppose that the above properties of TEC response are determined by the geodynamics of the Wenchuan earthquake.
The assemblage stilpnomelane–chlorite–phengitic mica: a geothermobarometer for blueschist and associated greenschist terranes

Two anhydrous equilibria can be written among the components of stilpnomelane, chlorite, white mica and quartz, namely 89 daphnite+131 Fe‐celadonite+190 quartz=96 stilpnomelane+71 muscovite, and amesite+Mg‐celadonite=muscovite+clinochlore. We assume that the free energy change of reaction, ΔG=ΔGo+ΣRT lnaij, is approximated by ΔG=A−BT +C(P−1)+ΣRT lnaij, where ΔGo is the free energy change of the end‐member components at temperature T and pressure P, ai is the activity of component i whose coefficient in the equilibrium is j, and A, B and C are constants to be determined. Values of C can be approximated by the change in volume on reaction, namely C=406.517 J/bar for the first reaction and C=0.613 J/bar for the second reaction. Constants A and B were determined by using six occurrences of the assemblage stilpnomelane–chlorite–white mica for which P–T have been otherwise estimated. Using solution models from the literature, linear regression gives for the first equation A=−6118.269 kJ, B=−4584.09 J/K, and for the second equation A=19.397 kJ, B=66.72 J/K. These values predict P–T within 0.5 kbar and 25 K for all occurrences, and appear reasonably robust relative to probable analytical errors. P–T are determined by intersection of the curves generated by given compositions in P–T space. Fine‐grained and/or zoned chlorite and white mica make application of the geothermobarometer difficult in some instances, but our work in the Bathurst region of New Brunswick suggests that, with patience and care, useful analyses can be obtained, and the database for the geothermobarometer greatly expanded.
Atmospheric deposition processes and their importance as sources of nutrients in a chaparral ecosystem of southern California

Precipitation and dry fallout were collected over a 2-year period in the Santa Ynez Mountains, Santa Barbara County, California, and analyzed for nutrient content. Mean annual depositions of Ca (2.2 kg/ha), K (0.7 kg/ha), NH4+-N (0.5 kg/ha), and NO3−-N (1.5 kg/ha) were largely derived from dryfall; depositions of Na (7.2 kg/ha), Mg (1.2 kg/ha), and SO4=-S (3.6 kg/ha) were important in both rainfall and dry fallout. These atmospheric inputs are equal to or larger than the typical annual losses reported in runoff from mature chaparral shrublands, but on the basis of these inputs, more than 70 years may be necessary to replace the nitrogen losses measured in volatilization and runoff after fire. The depositions of NO3−-N and SO4=-S at this remote site may be indicative of the natural levels of these ions which, in many other areas of California, are derived from anthropogenic sources.
Contrasting effects of temperature and winter mixing on the seasonal and inter-annual variability of the carbonate system in the Northeast Atlantic Ocean

Abstract. Future climate change as a result of increasing atmospheric CO2 concentrations is expected to strongly affect the oceans, with shallower winter mixing and consequent reduction in primary production and oceanic carbon drawdown in low and mid-latitudinal oceanic regions. Here we test this hypothesis by examining the effects of cold and warm winters on the carbonate system in the surface waters of the Northeast Atlantic Ocean for the period between 2005 and 2007. Monthly observations were made between the English Channel and the Bay of Biscay using a ship of opportunity program. During the colder winter of 2005/2006, the maximum depth of the mixed layer reached up to 650 m in the Bay of Biscay, whilst during the warmer (by 2.6 ± 0.5 °C) winter of 2006/2007 the mixed layer depth reached only 300 m. The inter-annual differences in late winter concentrations of nitrate (2.8 ± 1.1 μmol l−1) and dissolved inorganic carbon (22 ± 6 μmol kg−1, with higher concentrations at the end of the colder winter (2005/2006), led to differences in the dissolved oxygen anomaly and the chlorophyll α-fluorescence data for the subsequent growing season. In contrast to model predictions, the calculated air-sea CO2 fluxes (ranging from +3.7 to −4.8 mmol m−2 d−1) showed an increased oceanic CO2 uptake in the Bay of Biscay following the warmer winter of 2006/2007 associated with wind speed and sea surface temperature differences.
Simulated soil erosion from a semiarid typical steppe watershed using an integrated aeolian and fluvial prediction model

Total soil erosion is a result of both aeolian and fluvial processes, which is particularly true in semiarid regions. However, although physically interrelated, these two processes have conventionally been studied and modelled independently. Recently, a few researchers highlighted the importance and need of considering both processes in concert as well as their interactions, but they did not give specific modelling approaches or algorithms. The objectives of this study were to (1) formulate an integrated aeolian and fluvial prediction (IAFP) model, (2) parameterize the IAFP model for a semiarid steppe watershed located in northeastern China by using literature and historical data and (3) use the model to predict soil erosion in the watershed and assess the sensitivity of predicted erosion to environmental factors such as soil moisture and vegetation coverage. The results indicated that the IAFP model can capture the dynamic interactions between aeolian and fluvial erosion processes. For the study watershed, the model predicted a higher occurrence frequency of fluvial erosion than that of aeolian erosion and showed that these two processes almost equivalently contributed to the average total erosion of 0.07 mm year−1 across the simulation period. The ‘existing’ vegetation cover can provide an overall good protection of the soils, although the vegetation cover was predicted to play a larger role in a drier than a wetter year as well as in controlling aeolian than fluvial erosion. In addition, soil erosion was predicted to be more sensitive to soil moisture than land coverage. A soil moisture level of 0.23–0.25 was determined to be the probable switch point from aeolian‐to fluvial‐dominant process or vice versa. Copyright © 2012 John Wiley & Sons, Ltd.
Coefficient of variation as a measure of urban spatial attributes, using SPOT HRV and Landsat TM data

Abstract The variation of radiometric response over urban residential areas, as recorded by a sensor, is considered to be a function of the size and spatial distribution of housing units and the pixel size of the remote sensing system. Using data from thirty residential sites over the Sydney metropolitan area, and SPOT HRV and Landsat TM data, the relation between radiometric variability and the urban spatial measures of house size and housing density were analysed. Preliminary results show that the coefficient of variation is both a function of housing density and house size, for combined multiple-sensor data sets of different pixel sizes, and strongly related to house size for different classes of housing density using a single band of SPOT HRV XS-mode data.
Analysis of the Use of GNSS Systems in Road Construction

In road construction, construction machines are used for levelling and adjusting the earth's surface. These modern construction machines use a 3D GNSS levelling system to achieve the projected shape and elevation of terrain with the required accuracy within permitted setting-out deviations according to the project. In the area of interest were realized geodetic check measurements. The aim was to objectively assess and evaluate the practical applicability of connection between a construction machine and precise surveying instrument for determination of position and height in real time. Check measurements were based on the same reference points as were used for the construction machine in surface adjustment. The surveying instrument used for check measurements provided surveying results of required accuracy. Subsequently, the obtained data were used to compare the projected and the realized state. Height deviations of check points and deviations of the cubic content of laid material of individual sections were defined.
A mesoscale eddy pair southwest of Taiwan and its influence on deep circulation

[1] A pair of mesoscale eddies, namely, an anticyclonic eddy (AE) and a cyclonic eddy (CE), generated southwest of Taiwan was investigated using long-term moored observations augmented with satellite and reanalysis data. AE (CE) increased the upper-ocean current to 100 cm/s (50 cm/s) and generated temperature anomaly (T′) up to 7.5°C (−3.0°C). The vertical structure of AE presented a phase difference between T′ and velocity, with the core of T′ located south of the zero-velocity line. This phase difference induced a −28.5 ± 12.0 TW (1 TW = 1012 W) westward eddy heat transport southwest of Taiwan. AE also presented strong nonlinearity in the upper ocean and yielded an annual mean volume transport of 0.86 ± 0.15 Sv. Energy analysis showed that both baroclinic and barotropic instabilities were important for the generation and growth of the eddy pair, and contribution from wind work was relative small. In the deep sea, AE (CE) intensified the deep currents and generated large positive (negative) T′. The deep and surface currents flowed in opposite directions during the eddy events, which is consistent with the interpretation that the eddy pair is dominated by the first baroclinic mode. The observed deep-penetrating eddy pair could greatly influence the deep circulation of the northeastern South China Sea.
Principal components‐based regionalization of the Saudi Arabian climate

A climatic regionalization of Saudi Arabia that aims to classify the country into several homogenous groups is carried out, by grouping similar long‐term climatological features for precipitation and air temperature. Twenty‐seven stations are selected across Saudi Arabia for the analysis and 1985–2010 (26 years) is chosen as the common period. The employed methodology is a combination of mathematical and statistical techniques (principal components analysis and correlation); and a rather subjective physically detailed comparison with the long‐term climatology and topography for Saudi Arabia. Five groups have been identified: group A (Northern), B (Red Sea Coastal), C (Interior), D (Highland) and E (Southern). Each of the climatic groups exhibits a unique feature (with strong similarities among stations that belong to the same group), especially in terms of inter‐annual fluctuations and the degree of seasonality. This simplified overview of climatic characteristics is beneficial for assisting with economic planning, especially for any semi‐arid or arid land that is naturally vulnerable to climatic variability and extremes. The classification method used in this study, however, would be applicable for similar studies on regionalization in other regions.
Determining North Atlantic meridional transport variability from pressure on the western boundary: A model investigation

[1] In this paper, we investigate the possibility of determining North Atlantic meridional transport variability using pressure on the western boundary, focusing on the 42°N latitude of the Halifax WAVE array. We start by reviewing the theoretical foundations of this approach. Next, we present results from a model analysis, both statistical and dynamic, that demonstrate the feasibility of the approach. We consider how well we can quantify the meridional transport variability at 42°N given complete knowledge of bottom pressure across the basin and to what degree this quantification is degraded by first ignoring the effect of intervening topography and then by using only bottom pressure on the western boundary. We find that for periods of greater than 1 year, we can recover more than 90% of the variability of the main overturning cell at 42°N using only the western boundary pressure, provided that we remove the depth-averaged boundary pressure signal. This signal arises from a basin mode of bottom pressure variability, which has power at all time scales, but that does not in truth have a meridional transport signal associated with it, and from the geostrophic depth-independent compensation of the Ekman transport. An additional benefit of the removal of the depth-averaged pressure is that this high-frequency Ekman signal, which is essentially noise as far as monitoring the meridional overturning circulation for climatically important changes is concerned, is clearly separated from other modes.
A nonlinear regression model for weekly stream temperatures

To estimate weekly stream temperatures needed for fish habitat evaluation throughout an annual cycle, a four‐parameter, nonlinear function of weekly air temperatures was used. The regression function was developed separately for the warming season and the cooling season to take heat storage effects (hysteresis) into account. Regression functions were developed for stream temperatures recorded over a 3‐year period (1978–1980) at 584 U.S. Geological Survey (USGS) gaging stations in the contiguous United States. Representative air temperatures were obtained from the closest of 197 weather stations. The distance between a stream gaging station and the corresponding weather station was from 1.4 to 244 km. These distances did not have a significant effect on the goodness of fit. The regression model fitted the weekly stream temperatures at 573 stream gaging stations (98% of all records used) with a coefficient of determination larger than 0.7. For 491 records (84% of all gaging stations) the coefficient was >0.9. At 56 gaging stations (10% of all records used), estimated maximum stream temperatures were smaller than at least four weekly stream temperatures recorded for the period of study. Consequently, the model is deemed successfully applicable (with 99% confidence) to more than 89% of the stream gaging stations. The average coefficient of determination of the stream temperature projection for these stations is 0.93 ± 0.01.
Traveltime computation with the linearized eikonal equation for anisotropic media

A linearized eikonal equation is developed for transversely isotropic (TI) media with a vertical symmetry axis (VTI). It is linear with respect to perturbations in the horizontal velocity or the anisotropy parameter η. An iterative linearization of the eikonal equation is used as the basis for an algorithm of finite‐difference traveltime computations. A practical implementation of this iterative technique is to start with a background model that consists of an elliptically anisotropic, inhomogeneous medium, since traveltimes for this type of medium can be calculated efficiently using eikonal solvers, such as the fast marching method. This constrains the perturbation to changes in the anisotropy parameter η (the parameter most responsible for imaging improvements in anisotropic media). The iterative implementation includes repetitive calculation of η from traveltimes, which is then used to evaluate the perturbation needed for the next round of traveltime calculations using the linearized eikonal equation. Unlike isotropic media, interpolation is needed to estimate η in areas where the traveltime field is independent of η, such as areas where the wave propagates vertically.
Effect of fuel composition on combustion efficiency and emission factors for African savanna ecosystems

Savanna burning in Africa occurs over a wide range of environmental, vegetation, and land use conditions. The emission factors for trace emissions from these fires can vary by a factor of 6 to 8, depending on whether the fires burn in miombo woodlands or in ecosystems where grass vegetation dominates. Ground-based measurements of smoke emissions and aboveground biomass were made for fires in grassland and woodland savanna ecosystems in South Africa and Zambia. A high combustion efficiency ( η⌢) was measured for the pure grassland; i.e., a high proportion of carbon was released as CO2. The η⌢ was lower for woodland savanna ecosystems with variable amounts of grass and with a more compact layer of leaf material and litter lying near the ground. The η⌢ was found to be dependent on the ratio of grass to the sum of grass and litter. Models developed for estimating emissions were integrated in a nomogram for estimating total emissions of CO2, CO, CH4, nonmethane hydrocarbons, and particles of less than 2.5 μm diameter per unit area.
Biogeochemistry of Estuaries

Biogeochemistry of Estuaries offers a comprehensive and interdisciplinary approach to understanding biogeochemical cycling in estuaries. Designed as a text for intermediate to advanced students, this book utilizes numerous illustrations and an extensive literature base to impart the current state-of-the-art knowledge in this field. While many of the existing books in estuarine science are comprised of edited volumes, typically focused on highly specific topics in estuaries, Biogeochemistry of Estuaries provides, for the first time, a unique foundation in the areas of geomorphology, geochemistry, biochemistry, aqueous chemistry, and ecology, while making strong linkages (trhoughout the text) to ecosystem-based processes in estuarine sciences. Estuaries, located at the interface between land and the coastal ocean are dynamic, highly productive systems that, in many cases, have been historically associated with development of many of the great centers of early human civilization. Consequentially, these systems have and continue to be highly impacted by anthropogenic inputs. This timely book takes the foundational basis of elemental cycling in estuarine and applies it to estuarine management issues. Biogeochemistry of Estuaries will be welcomed by estuarine/marine scientists, ecologists, biogeochemists, and environmentalists around the world.
Effects of solute breakthrough curve tail truncation on residence time estimates: A synthesis of solute tracer injection studies

[1] Hydrologic transport and retention strongly affect biogeochemical processes that are critical to stream ecosystems. Tracer injection studies are often used to characterize solute transport and retention in stream reaches, but the range of processes accurately resolved with this approach is not clear. Solute residence time distributions depend on both in-stream mixing and exchange with the hyporheic zone and the larger groundwater system. Observed in-stream breakthrough curves have most commonly been modeled with in-stream advection-dispersion plus an exponential residence time distribution, but process-based models suggest that hyporheic exchange is a fractal process, and that hyporheic residence time distributions are more appropriately characterized by power law tailing. We synthesized results from a variety of tracer-injection studies to investigate the information content of tracer breakthrough curves. We found that breakthrough curve tails are often not well characterized in stream tracer experiments. The two main reasons for this are: 1) experimental truncation of breakthrough curves, which occurs when sampling ends before all tracer mass reaches the sampling location, and 2) sensitivity truncation of breakthrough curves, when tracer concentrations in the tail are too low to be detected reliably above background levels. Tail truncation reduces observed mass recovery and obscures assessment of breakthrough curve tailing and solute residence time. Failure to consider tail truncation leads to underestimation of hyporheic exchange and solute retention and to corresponding overestimation of hyporheic biogeochemical transformation rates. Based on these findings, we propose criteria for improved design of in-stream tracer injection experiments to improve assessment of solute tailing behavior.
Evidence for xenon silicates at high pressure and temperature

We present evidence for the stability of xenon silicate phases at deep crustal conditions. High pressure‐temperature investigations of the Xe‐SiO2 system were conducted using diamond‐anvil cells combined with laser heating and external resistive heating. A new compound was synthesized at 0.7–1.5 GPa and 1500–1750° as evidenced by Raman spectroscopy. Upon temperature quenching, the material undergoes a back transformation to another Xe‐SiO2 phase stable up to 2.14 GPa. X‐ray diffraction data show that this second phase has a cubic structure [a = 8.03(±0.03) Å] and a bulk modulus of 20(±0.6) GPa. The phase was found to have a minimum of 4 wt% Xe from electron microprobe analysis. These results indicate that the chemical affinity of Xe and silica increases at high pressures and temperatures. Hence Xe can be potentially hosted by silicates in the crust, which helps to resolve the geochemical paradox of the ‘missing Xe’ in the atmospheres of the Earth and Mars.
Hydrological processes in major types of Chinese forest

Overexploitation of forest resources in China has caused serious concerns over its negative impacts on water resources, biodiversity, soil erosion, wildlife habitat and community stability. One key concern is the impact of forestry practices on hydrological processes, particularly the effect of forest harvest on water quality and quantity. Since the mid 1980s, a series of scientific studies on forest hydrology have been initiated in major types of forest across the country, including Korean pine (Pinus koraiensis), Chinese fir (Cunninghamia lanceolata), oak (Quercus mongolica), larch (Larix gmelinii), faber fir (Abies fabri), Chinese pine (Pinus tabulaeformis), armand pine (Pinus arandi), birch (Betula platyphylla) and some tropical forests. These studies measured rainfall interception, streamflow, evapotranspiration and impacts of forest management (clearcutting and reforestation). This paper reviews key findings from these forest hydrological studies conducted over the past 20 years in China.