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Bugaіenko, Olena. „THE LAND REALLOCATION MODEL IN THE COURSE OF AGRICULTURAL LAND CONSOLIDATION IN UKRAINE“. Geodesy and cartography 44, Nr. 3 (16.10.2018): 106–12. http://dx.doi.org/10.3846/gac.2018.2049.
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The issue of the effectiveness of agricultural land consolidation in the environment of land relations being reshaped, with Ukraine as the example has been scrutinized in the research. Land reallocation as the key constituent of land consolidation has been considered according to the existing approaches. Necessity for substantiation of the peerness of land plots to be reallocated has been singled out. Key factors influencing the peer agricultural land exchange in the process of reallocation have been defined. It is offered to define the peerness of agricultural land plots by a set of qualitative and spatial and technological characteristics. The improvement of the existing approaches to land reallocation by limiting for the reallocated land plots peerness by the preset characteristics has been suggested. The gist of the modelling is the minimization of distance from land plot to the farmhouse. Technical data characterizing the qualitative and spatial and technological characteristics of land plots at the reallotment have been defined. The assessment of the provided reallocation model with the example of the agricultural land mass has been provided. Land reallocation is accomplished by the voluntary land plot exchange. The analysis of the reallocation results using the provided model has been executed.
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Packet, W., und J. P. De Greve. „Who is Who in Algol-Land ? - Part II -“. International Astronomical Union Colloquium 107 (1989): 339. http://dx.doi.org/10.1017/s0252921100087972.
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AbstractIn part I (De Greve and Packet) we have investigated the occurrence of reversed phases of mass-transfer during Case A evolution in close binaries. If the initial period of a system is shorter than 1 - 2 days (Early Case A) the reversed phase starts before core hydrogen exhaustion of the gainer (part I). This type of evolution is characterized by at least two phases of slow mass-transfer.We have computed the evolution of four Early Case A systems with initial masses of the loser equal to 3 Mo and 5 Mo. These four systems start mass-exchange when Xc of the primary has decreased to 0.525 (75% of its initial value). They all experience two phases of slow mass-transfer.We find that both phases have about the same duration for all systems. The mass ratios are clearly distinct, being closer to unity during the first phase. In the Hertzsprung-Russell, mass-radius and mass-luminosity diagrams both components remain close to the main-sequence band during slow mass-transfer. Evolution as an Algol is ended when both components overflow their outer critical surface after a second reversal of the mass-transfer.Observed Algol systems evolving in Early Case A are scarce. A search thruogh the catalogue by Giuricin et al. gives us the following candidates: X Tri, SX Aur and V Pup. Based on their mass ratios, SX Aur can tentatively be assigned to the first phase of slow mass transfer and X Tri to the second phase. For V Pup (which is more massive) this choice can not be made with certainty.
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Adhikari, Surendra, Erik R. Ivins, Eric Larour, Lambert Caron und Helene Seroussi. „A kinematic formalism for tracking ice–ocean mass exchange on the Earth's surface and estimating sea-level change“. Cryosphere 14, Nr. 9 (02.09.2020): 2819–33. http://dx.doi.org/10.5194/tc-14-2819-2020.
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Abstract. Polar ice sheets are important components of the Earth system. As the geometries of land, ocean and ice sheets evolve, they must be consistently captured within the lexicon of geodesy. Understanding the interplay between the processes such as ice-sheet dynamics, solid-Earth deformation, and sea-level adjustment requires both geodetically consistent and mass-conserving descriptions of evolving land and ocean domains, grounded ice sheets and floating ice shelves, and their respective interfaces. Here we present mathematical descriptions of a generic level set that can be used to track both the grounding lines and coastlines, in light of ice–ocean mass exchange and complex feedbacks from the solid Earth and sea level. We next present a unified method to accurately compute the sea-level contribution of evolving ice sheets based on the change in ice thickness, bedrock elevation and mean sea level caused by any geophysical processes. Our formalism can be applied to arbitrary geometries and at all timescales. While it can be used for applications with modeling, observations and the combination of two, it is best suited for Earth system models, comprising ice sheets, solid Earth and sea level, that seek to conserve mass.
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Kleidon, A., M. Renner und P. Porada. „Estimates of the climatological land surface energy and water balance derived from maximum convective power“. Hydrology and Earth System Sciences 18, Nr. 6 (17.06.2014): 2201–18. http://dx.doi.org/10.5194/hess-18-2201-2014.
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Abstract. The land surface energy and water balances are tightly coupled by the partitioning of absorbed solar radiation into terrestrial radiation and the turbulent fluxes of sensible and latent heat, as well as the partitioning of precipitation into evaporation and runoff. Evaporation forms the critical link between these two balances. Its rate is strongly affected by turbulent exchange as it provides the means to efficiently exchange moisture between the heated, moist surface and the cooled, dry atmosphere. Here, we use the constraint that this mass exchange operates at the thermodynamic limit of maximum power to derive analytical expressions for the partitioning of the surface energy and water balances on land. We use satellite-derived forcing of absorbed solar radiation, surface temperature and precipitation to derive simple spatial estimates for the annual mean fluxes of sensible and latent heat and evaluate these estimates with the ERA-Interim reanalysis data set and observations of the discharge of large river basins. Given the extremely simple approach, we find that our estimates explain the climatic mean variations in net radiation, evaporation, and river discharge reasonably well. We conclude that our analytical, minimum approach provides adequate first order estimates of the surface energy and water balance on land and that the thermodynamic limit of maximum power provides a useful closure assumption to constrain the energy partitioning at the land surface.
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Kleidon, A., M. Renner und P. Porada. „Estimates of the climatological land surface energy and water balance derived from maximum convective power“. Hydrology and Earth System Sciences Discussions 11, Nr. 1 (08.01.2014): 265–306. http://dx.doi.org/10.5194/hessd-11-265-2014.
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Abstract. The land surface energy- and water balances are tightly coupled by the partitioning of absorbed solar radiation into terrestrial radiation and the turbulent fluxes of sensible and latent heat, as well as the partitioning of precipitation into evaporation and runoff. Evaporation forms the critical link between these two balances. Its rate is strongly affected by turbulent exchange as it provides the means to efficiently exchange moisture between the heated, moist surface and the cooled, dry atmosphere. Here, we use the constraint that this mass exchange operates at the thermodynamic limit of maximum power to derive analytical expressions for the partitioning of the surface energy- and water balances on land. We use satellite-derived forcing of absorbed solar radiation, surface temperature and precipitation to derive simple spatial estimates for the annual mean fluxes of sensible and latent heat and evaluate these estimates with the ERA-Interim reanalysis dataset and observations of the discharge of large river basins. Given the extremely simple approach, we find that our estimates explain the climatic mean variations in net radiation, evaporation, and river discharge reasonably well. We conclude that our analytical, minimum approach provides adequate first order estimates of the surface energy- and water balance on land and that the thermodynamic limit of maximum power provides a useful closure assumption to constrain the energy partitioning at the land surface.
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Medeiros, Brian, Alex Hall und Bjorn Stevens. „What Controls the Mean Depth of the PBL?“ Journal of Climate 18, Nr. 16 (15.08.2005): 3157–72. http://dx.doi.org/10.1175/jcli3417.1.
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Abstract The depth of the planetary boundary layer (PBL) is a climatologically important quantity that has received little attention on regional to global scales. Here a 10-yr climatology of PBL depth from the University of California, Los Angeles (UCLA) atmospheric GCM is analyzed using the PBL mass budget. Based on the dominant physical processes, several PBL regimes are identified. These regimes tend to exhibit large-scale geographic organization. Locally generated buoyancy fluxes and static stability control PBL depth nearly everywhere, though convective mass flux has a large influence at tropical marine locations. Virtually all geographical variability in PBL depth can be linearly related to these quantities. While dry convective boundary layers dominate over land, stratocumulus-topped boundary layers are most common over ocean. This division of regimes leads to a dramatic land–sea contrast in PBL depth. Diurnal effects keep mean PBL depth over land shallow despite large daytime surface fluxes. The contrast arises because the large daily exchange of heat and mass between the PBL and free atmosphere over land is not present over the ocean, where mixing is accomplished by turbulent entrainment. Consistent treatment of remnant air from the deep, daytime PBL is necessary for proper representation of this diurnal behavior over land. Many locations exhibit seasonal shifts in PBL regime related to changes in PBL clouds. These shifts are controlled by seasonal variations in buoyancy flux and static stability.
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Shin, Bum Shick, und Kyu Han Kim. „Environmental Assessments for Wetlands and Estuaries Management near Tidal Power Plant Using of Mass Balance Simulation“. Applied Mechanics and Materials 672-674 (Oktober 2014): 453–58. http://dx.doi.org/10.4028/www.scientific.net/amm.672-674.453.
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The closed bay formed by a tidal power plant on the west coast of Korea has caused water quality to change due to nutrient increase and salinity alternation. The nutrients of the inner bay are often kept a balance with the aid of the outflow at the mouth of the bay. Hence it is necessary to minimize the environmental effects by forecasting the potential environmental changes caused by a tidal power construction. Seasonal observations of mass balance in the inner and outer Garolim Bay were performed. The low quality nutrients released from sediments, land and river were more dominant than the nutrients released from the outer bay in the study area. It was observed that the tidal power plant construction made water exchange ratio 57%.Various mitigation strategies such as water gates were studied so that the water exchange rate can be reduced. The change in the water exchange ratio is significantly reduced as the cross-section and the number of water gates is increased. The water exchange ratio was decreased by 8%, which increased nutrients in the inner bay. Results of numerical the nutrients decreased with the 7% increase in the inflow while the decrease in outflow discharges. However, it is considered only 0.2% increase in the entire mass balance of Garolim Bay relatively inadequate to mitigate the environmental impact.
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Sun, Yibo, Junyong Ma, Bilige Sude, Xingwen Lin, Haolu Shang, Bing Geng, Zhaoyan Diao, Jiaqiang Du und Zhanjun Quan. „A UAV-Based Eddy Covariance System for Measurement of Mass and Energy Exchange of the Ecosystem: Preliminary Results“. Sensors 21, Nr. 2 (08.01.2021): 403. http://dx.doi.org/10.3390/s21020403.
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Airborne eddy covariance (EC) measurement is one of the most effective methods to directly measure the surface mass and energy fluxes at the regional scale. It offers the possibility to bridge the scale gap between local- and global-scale measurements by ground-based sites and remote-sensing instrumentations, and to validate the surface fluxes estimated by satellite products or process-based models. In this study, we developed an unmanned aerial vehicle (UAV)-based EC system that can be operated to measure the turbulent fluxes in carbon dioxides, momentum, latent and sensible heat, as well as net radiation and photosynthetically active radiation. Flight tests of the developed UAV-based EC system over land were conducted in October 2020 in Inner Mongolia, China. The in-flight calibration was firstly conducted to correct the mounting error. Then, three flight comparison tests were performed, and we compared the measurement with those from a ground tower. The results, along with power spectral comparison and consideration of the differing measurement strategies indicate that the system can resolve the turbulent fluxes in the encountered measurement condition. Lastly, the challenges of the UAV-based EC method were discussed, and potential improvements with further development were explored. The results of this paper reveal the considerable potential of the UAV-based EC method for land surface process studies.
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Sun, Yibo, Junyong Ma, Bilige Sude, Xingwen Lin, Haolu Shang, Bing Geng, Zhaoyan Diao, Jiaqiang Du und Zhanjun Quan. „A UAV-Based Eddy Covariance System for Measurement of Mass and Energy Exchange of the Ecosystem: Preliminary Results“. Sensors 21, Nr. 2 (08.01.2021): 403. http://dx.doi.org/10.3390/s21020403.
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Airborne eddy covariance (EC) measurement is one of the most effective methods to directly measure the surface mass and energy fluxes at the regional scale. It offers the possibility to bridge the scale gap between local- and global-scale measurements by ground-based sites and remote-sensing instrumentations, and to validate the surface fluxes estimated by satellite products or process-based models. In this study, we developed an unmanned aerial vehicle (UAV)-based EC system that can be operated to measure the turbulent fluxes in carbon dioxides, momentum, latent and sensible heat, as well as net radiation and photosynthetically active radiation. Flight tests of the developed UAV-based EC system over land were conducted in October 2020 in Inner Mongolia, China. The in-flight calibration was firstly conducted to correct the mounting error. Then, three flight comparison tests were performed, and we compared the measurement with those from a ground tower. The results, along with power spectral comparison and consideration of the differing measurement strategies indicate that the system can resolve the turbulent fluxes in the encountered measurement condition. Lastly, the challenges of the UAV-based EC method were discussed, and potential improvements with further development were explored. The results of this paper reveal the considerable potential of the UAV-based EC method for land surface process studies.
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Tennyson, Robert. „From Unanimity to Proportionality: Assent Standards and the Parliamentary Enclosure Movement“. Law and History Review 31, Nr. 1 (Februar 2013): 199–231. http://dx.doi.org/10.1017/s073824801200017x.
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“Enclosure” has long been shorthand for describing the exchange of scattered strips of land and common rights for cohesive plots in premodern and modern England. Proprietors who farmed long strips of land throughout a village or released cattle on unused waste would receive at enclosure regular plots commensurate in value with earlier interests. The process of enclosure in a village could be gradual, as it predominantly was for much of the premodern period. Alternatively, as increasingly occurred in the modern era, the proprietors could enclose their lands in concert. Figure 1, two maps of Helmdon in Northamptonshire, depicts the vast change in holdings that could occur through enclosure.
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Moursy, Ali, Abdelgalil A, Ibrahim M.S, Abdelhady A.A und Mustafa A.A. „Actual and Potential Land Productivity of Some Soils of Sohag-Red Sea Road Sides, Eastern Desert, Egypt“. International Journal of Agricultural and Applied Sciences 1, Nr. 1 (30.06.2020): 68–74. http://dx.doi.org/10.52804/ijaas2020.1114.
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Egyptian Government focuses on development projects especially in new lands such as Sohag-Red Sea road to improve tourism and agricultural activities. This study aims to assess the actual and potential land productivity. Seventeen soil profiles were chosen depending on the six mapping units of the study area. Soil profiles were drilled and soil samples were collected from each horizon. Nine land characteristics were measured/estimated viz. soil moisture content (H), drainage (D), depth (P), texture (T), soluble salts content (S), average nutrient content (N), organic matter content (O), cationic exchange capacity (A) and reserves weatherable minerals (M). Soil samples were analyzed for their mentioned parameters using the standard methods of soil analysis. Accordingly, land productivity (PI) and potentiality (P⸌I) indices were calculated for all studied soil profiles. The results revealed that actual land productivity of the studied area is extremely poor and can be enhanced 17 times by improving soil moisture content, texture, and organic matter content as the most important controlling-factors. Actual and potential land productivity maps were generated using Arc GIS 10.1 software. These results may help decision-makers for new lands reclamation planning and better agricultural production.
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Lu, Sha, und Hongchao Zuo. „Improvement and Validation of the Common Land Model on Cropland Covered by Plastic Film in the Arid Region of China“. Journal of Applied Meteorology and Climatology 57, Nr. 9 (September 2018): 2071–89. http://dx.doi.org/10.1175/jamc-d-17-0185.1.
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AbstractPlastic mulch is a technology used worldwide to inhibit soil evaporation and increase crop yield. The properties of plastic film are significantly different from those of the soil. Plastic mulch not only significantly alters the physical attributes of the underlying surface, but also blocks the energy and mass exchanges between the land surface and the atmosphere. This latter situation has not been depicted in current land-surface models. This study develops a detailed new model, known as CoLM-mulch, by incorporating a plastic mulch–layer submodel and a dynamic parameterization scheme of surface albedo into the Common Land Model (CoLM) land-surface process model. The updated model elements are based on data collected from an experiment that examined land–atmosphere interaction at a plastic-film-covered cropland site in an arid region of northwestern China. Results suggest that the improved CoLM-mulch could reasonably simulate the diurnal variations of soil temperature and moisture, together with radiation, water, heat, and carbon dioxide (CO2) fluxes, on the cropland underlying a surface with a plastic film covering. The CoLM-mulch efficiency is higher, the deviations between the simulations and observations are minor, and the dynamic parameterization scheme for surface albedo is more reasonable and appropriate. Relative to CoLM simulations, the inclusion of plastic mulch with special optical properties in the model shows slight improvements in the simulations of the surface albedo and the radiation balance. By limiting the underlying soil evaporation and changing the aerodynamic resistances, plastic mulch in the model has influences on the turbulent exchanges between the atmosphere and the land surface. The soil temperature and moisture are improved by the inclusion of transparent plastic mulch in the model, which not only suppresses the CO2 generated by soil respiration, but also alters the CO2 exchange process between the canopy and the atmosphere as a result of the vegetation net assimilation controlled by the soil water and heat conditions.
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Renner, Maik, Axel Kleidon, Martyn Clark, Bart Nijssen, Marvin Heidkamp, Martin Best und Gab Abramowitz. „How Well Can Land-Surface Models Represent the Diurnal Cycle of Turbulent Heat Fluxes?“ Journal of Hydrometeorology 22, Nr. 1 (Januar 2021): 77–94. http://dx.doi.org/10.1175/jhm-d-20-0034.1.
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AbstractThe diurnal cycle of solar radiation represents the strongest energetic forcing and dominates the exchange of heat and mass of the land surface with the atmosphere. This diurnal heat redistribution represents a core of land–atmosphere coupling that should be accurately represented in land surface models (LSMs), which are critical parts of weather and climate models. We employ a diagnostic model evaluation approach using a signature-based metric that describes the diurnal variation of heat fluxes. The metric is obtained by decomposing the diurnal variation of surface heat fluxes into their direct response and the phase lag to incoming solar radiation. We employ the output of 13 different LSMs driven with meteorological forcing of 20 FLUXNET sites (PLUMBER dataset). All LSMs show a poor representation of the evaporative fraction and thus the diurnal magnitude of the sensible and latent heat flux under cloud-free conditions. In addition, we find that the diurnal phase of both heat fluxes is poorly represented. The best performing model only reproduces 33% of the evaluated evaporative conditions across the sites. The poor performance of the diurnal cycle of turbulent heat exchange appears to be linked to how models solve for the surface energy balance and redistribute heat into the subsurface. We conclude that a systematic evaluation of diurnal signatures is likely to help to improve the simulated diurnal cycle, better represent land–atmosphere interactions, and therefore improve simulations of the near-surface climate.
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Blunier, T., M. L. Bender, B. Barnett und J. C. von Fisher. „Planetary fertility during the past 400 ka based on the triple isotope composition of O<sub>2</sub> in trapped gases from the Vostok ice core“. Climate of the Past Discussions 8, Nr. 1 (30.01.2012): 435–79. http://dx.doi.org/10.5194/cpd-8-435-2012.
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Abstract. The productivity of the biosphere leaves its imprint on the isotopic composition of atmospheric oxygen. Ultimately atmospheric oxygen, through photosynthesis, originates from seawater. Fractionations during the passage from seawater to atmospheric O2 and during respiration are mass dependent, affecting δ17O about half as much as δ18O. An "anomalous" (also termed mass independent) fractionation process changes δ17O about 1.7 times as much as δ18O during isotope exchange between O2 and CO2 in the stratosphere. The relative rates of biological O2 production and stratospheric processing determine the relationship between δ17O and δ18O of O2 in the atmosphere. Variations of this relationship thus allow us to estimate changes in the rate of mass dependent O2 production by photosynthesis vs. the rate of mass independent O2-CO2 exchange in the stratosphere. However, the analysis of the 17O anomaly is complicated because each hydrological and biological process influencing δ17O and δ18O fractionates 17O and 18O in slightly different proportions. In this study we present oxygen data covering the last 400 kyr from the Vostok ice core. We reconstruct oxygen productivities from the triple isotope composition of atmospheric oxygen with a box model. Our steady state model for the oxygen cycle takes into account fractionation during photosynthesis and respiration of the land and ocean biosphere as well as fractionation when oxygen passes through the stratosphere. We consider changes of fractionation factors linked to climate variations taking into account the span of estimates of the main factors affecting our calculations. We find that ocean oxygen productivity was likely elevated relative to modern during glacials. However, this increase probably did not fully compensate for a reduction in land ocean productivity resulting in a slight reduction in total oxygen production during glacials.
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Stolle, Christian, Mariana Ribas-Ribas, Thomas H. Badewien, Jonathan Barnes, Lucy J. Carpenter, Rosie Chance, Lars Riis Damgaard et al. „The MILAN Campaign: Studying Diel Light Effects on the Air–Sea Interface“. Bulletin of the American Meteorological Society 101, Nr. 2 (01.02.2020): E146—E166. http://dx.doi.org/10.1175/bams-d-17-0329.1.
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Abstract The sea surface microlayer (SML) at the air–sea interface is <1 mm thick, but it is physically, chemically, and biologically distinct from the underlying water and the atmosphere above. Wind-driven turbulence and solar radiation are important drivers of SML physical and biogeochemical properties. Given that the SML is involved in all air–sea exchanges of mass and energy, its response to solar radiation, especially in relation to how it regulates the air–sea exchange of climate-relevant gases and aerosols, is surprisingly poorly characterized. MILAN (Sea Surface Microlayer at Night) was an international, multidisciplinary campaign designed to specifically address this issue. In spring 2017, we deployed diverse sampling platforms (research vessels, radio-controlled catamaran, free-drifting buoy) to study full diel cycles in the coastal North Sea SML and in underlying water, and installed a land-based aerosol sampler. We also carried out concurrent ex situ experiments using several microsensors, a laboratory gas exchange tank, a solar simulator, and a sea spray simulation chamber. In this paper we outline the diversity of approaches employed and some initial results obtained during MILAN. Our observations of diel SML variability show, for example, an influence of (i) changing solar radiation on the quantity and quality of organic material and (ii) diel changes in wind intensity primarily forcing air–sea CO2 exchange. Thus, MILAN underlines the value and the need of multidiciplinary campaigns for integrating SML complexity into the context of air–sea interaction.
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Bisht, Gautam, Maoyi Huang, Tian Zhou, Xingyuan Chen, Heng Dai, Glenn E. Hammond, William J. Riley, Janelle L. Downs, Ying Liu und John M. Zachara. „Coupling a three-dimensional subsurface flow and transport model with a land surface model to simulate stream–aquifer–land interactions (CP v1.0)“. Geoscientific Model Development 10, Nr. 12 (12.12.2017): 4539–62. http://dx.doi.org/10.5194/gmd-10-4539-2017.
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Abstract. A fully coupled three-dimensional surface and subsurface land model is developed and applied to a site along the Columbia River to simulate three-way interactions among river water, groundwater, and land surface processes. The model features the coupling of the Community Land Model version 4.5 (CLM4.5) and a massively parallel multiphysics reactive transport model (PFLOTRAN). The coupled model, named CP v1.0, is applied to a 400 m × 400 m study domain instrumented with groundwater monitoring wells along the Columbia River shoreline. CP v1.0 simulations are performed at three spatial resolutions (i.e., 2, 10, and 20 m) over a 5-year period to evaluate the impact of hydroclimatic conditions and spatial resolution on simulated variables. Results show that the coupled model is capable of simulating groundwater–river-water interactions driven by river stage variability along managed river reaches, which are of global significance as a result of over 30 000 dams constructed worldwide during the past half-century. Our numerical experiments suggest that the land-surface energy partitioning is strongly modulated by groundwater–river-water interactions through expanding the periodically inundated fraction of the riparian zone, and enhancing moisture availability in the vadose zone via capillary rise in response to the river stage change. Meanwhile, CLM4.5 fails to capture the key hydrologic process (i.e., groundwater–river-water exchange) at the site, and consequently simulates drastically different water and energy budgets. Furthermore, spatial resolution is found to significantly impact the accuracy of estimated the mass exchange rates at the boundaries of the aquifer, and it becomes critical when surface and subsurface become more tightly coupled with groundwater table within 6 to 7 meters below the surface. Inclusion of lateral subsurface flow influenced both the surface energy budget and subsurface transport processes as a result of river-water intrusion into the subsurface in response to an elevated river stage that increased soil moisture for evapotranspiration and suppressed available energy for sensible heat in the warm season. The coupled model developed in this study can be used for improving mechanistic understanding of ecosystem functioning and biogeochemical cycling along river corridors under historical and future hydroclimatic changes. The dataset presented in this study can also serve as a good benchmarking case for testing other integrated models.
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Linhardt, Tobias, Joseph S. Levy und Christoph K. Thomas. „Water tracks intensify surface energy and mass exchange in the Antarctic McMurdo Dry Valleys“. Cryosphere 13, Nr. 8 (19.08.2019): 2203–19. http://dx.doi.org/10.5194/tc-13-2203-2019.
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Abstract. The hydrologic cycle in the Antarctic McMurdo Dry Valleys (MDV) is mainly controlled by surface energy balance. Water tracks are channel-shaped high-moisture zones in the active layer of permafrost soils and are important solute and water pathways in the MDV. We evaluated the hypothesis that water tracks alter the surface energy balance in this dry, cold, and ice-sheet-free environment during summer warming and may therefore be an increasingly important hydrologic feature in the MDV in the face of landscape response to climate change. The surface energy balance was measured for one water track and two off-track reference locations in Taylor Valley over 26 d of the Antarctic summer of 2012–2013. Turbulent atmospheric fluxes of sensible heat and evaporation were observed using the eddy-covariance method in combination with flux footprint modeling, which was the first application of this technique in the MDV. Soil heat fluxes were analyzed by measuring the heat storage change in the thawed layer and approximating soil heat flux at ice table depth by surface energy balance residuals. For both water track and reference locations over 50 % of net radiation was transferred to sensible heat exchange, about 30 % to melting of the seasonally thawed layer, and the remainder to evaporation. The net energy flux in the thawed layer was zero. For the water track location, evaporation was increased by a factor of 3.0 relative to the reference locations, ground heat fluxes by 1.4, and net radiation by 1.1, while sensible heat fluxes were reduced down to 0.7. Expecting a positive snow and ground ice melt response to climate change in the MDV, we entertained a realistic climate change response scenario in which a doubling of the land cover fraction of water tracks increases the evaporation from soil surfaces in lower Taylor Valley in summer by 6 % to 0.36 mm d−1. Possible climate change pathways leading to this change in landscape are discussed. Considering our results, an expansion of water track area would make new soil habitats accessible, alter soil habitat suitability, and possibly increase biological activity in the MDV. In summary, we show that the surface energy balance of water tracks distinctly differs from that of the dominant dry soils in polar deserts. With an expected increase in area covered by water tracks, our findings have implications for hydrology and soil ecosystems across terrestrial Antarctica.
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Morris, Cindy E. „Phytobiomes Contribute to Climate Processes that Regulate Temperature, Wind, Cloud Cover, and Precipitation“. Phytobiomes Journal 2, Nr. 2 (Januar 2018): 55–61. http://dx.doi.org/10.1094/pbiomes-12-17-0050-p.
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In the management of plant health, climate and weather can be perceived as variables of the abiotic environment to which plants, and their associated biota, are passively subjected. However, research on Earth systems is now revealing how weather and climate can be markedly influenced by land use and by the types and extent of vegetation in particular. Plant-associated biota can alter the properties of vegetation that underlie the mechanisms by which it influences weather and climate. Therefore, it is important to consider the extent to which phytobiomes could impact climate and weather and the potential consequences for plant health and production and for processes that possibly exacerbate or modulate climate change. This commentary will illustrate how the exchange of mass and energy between the atmosphere and land cover modulates temperature, winds, cloud formation and precipitation at local, regional and even greater scales and the role of plants and their associated biota in these effects. Via these exchanges, phytobiomes contribute to the climatic and weather variations to which they are in turn subjected. This argues for an expanded perspective of phytobiomes that considers their role in Earth system processes and that integrates knowledge of land-atmosphere feedbacks into the management practices of crops and other vegetation. This knowledge will contribute to a vision of how management of the biophysical setting of crop cultivation could leverage environmental conditions locally and regionally. [Formula: see text] Copyright © 2018 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .
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Raven, John A. „Evolution and palaeophysiology of the vascular system and other means of long-distance transport“. Philosophical Transactions of the Royal Society B: Biological Sciences 373, Nr. 1739 (18.12.2017): 20160497. http://dx.doi.org/10.1098/rstb.2016.0497.
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Photolithotrophic growth on land using atmospheric CO 2 inevitably involves H 2 O vapour loss. Embryophytes greater than or equal to 100 mm tall are homoiohydric and endohydric with mass flow of aqueous solution through the xylem in tracheophytes. Structural details in Rhynie sporophytes enable modelling of the hydraulics of H 2 O supply to the transpiring surface, and the potential for gas exchange with the Devonian atmosphere. Xylem carrying H 2 O under tension involves programmed cell death, rigid cell walls and embolism repair; fossils provide little evidence on these functions other than the presence of lignin. The phenylalanine ammonia lyase essential for lignin synthesis came from horizontal gene transfer. Rhynie plants lack endodermes, limiting regulation of the supply of soil nutrients to shoots. The transfer of organic solutes from photosynthetic sites to growing and storage tissues involves mass flow through phloem in extant tracheophytes. Rhynie plants show little evidence of phloem; possible alternatives for transport of organic solutes are discussed. Extant examples of the arbuscular mycorrhizas found in Rhynie plants exchange soil-derived nutrients (especially P) for plant-derived organic matter, involving bidirectional mass flow along the hyphae. The aquatic cyanobacteria and the charalean Palaeonitella at Rhynie also have long-distance (relative to the size of the organism) transport. This article is part of a discussion meeting issue ‘The Rhynie cherts: our earliest terrestrial ecosystem revisited’.
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Tiruneh, Gizachew Ayalew, Tiringo Yilak Alemayehu, Derege Tsegaye Meshesha, Eduardo Saldanha Vogelmann, José Miguel Reichert und Nigussie Haregeweyn. „Spatial variability of soil chemical properties under different land-uses in Northwest Ethiopia“. PLOS ONE 16, Nr. 6 (23.06.2021): e0253156. http://dx.doi.org/10.1371/journal.pone.0253156.
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The understanding of the spatial variation of soil chemical properties is critical in agriculture and the environment. To assess the spatial variability of soil chemical properties in the Fogera plain, Ethiopia, we used Inverse Distance Weighting (IDW), pair-wise comparisons, descriptive analysis, and principal component analysis (PCA). In 2019, soil samples were collected at topsoil (a soil depth of 0–20 cm) from three representative land-uses (cropland, plantation forestland, and grazing lands) using a grid-sampling design. The variance analysis for soil pH, available phosphorus (avP), organic carbon (OC), total nitrogen (TN), electrical conductivity (EC), exchangeable potassium (exchK), exchangeable calcium (exchCa), and cation exchange capacity (CEC) revealed significant differences among the land-uses. The highest mean values of pH (8.9), avP (32.99 ppm), OC (4.82%), TN (0.39%), EC (2.28 dS m−1), and exchK (2.89 cmol (+) kg-1) were determined under grazing land. The lowest pH (6.2), OC (2.3%), TN (0.15%), and EC (0.11 dS m−1) were recorded in cultivated land. The PCA result revealed that the land-use change was responsible for most soil chemical properties, accounting for 93.32%. Soil maps can help identify the nutrient status, update management options, and increase productivity and profit. The expansion of cultivated lands resulted in a significant decrease in soil organic matter. Thus, soil management strategies should be tailored to replenish the soil nutrient content while maintaining agricultural productivity in the Fogera plain.
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Carvalho, João Luís Nunes, Cerri Carlos Eduardo Pelegrino, Brigitte Josefine Feigl, Marisa de Cássia Píccolo, Vicente de Paula Godinho, Uwe Herpin und Carlos Clemente Cerri. „Conversion of cerrado into agricultural land in the south-western Amazon: carbon stocks and soil fertility“. Scientia Agricola 66, Nr. 2 (April 2009): 233–41. http://dx.doi.org/10.1590/s0103-90162009000200013.
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Land use change and land management practices can modify soil carbon (C) dynamics and soil fertility. This study evaluated the effect of tillage systems (no-tillage - NT and conventional tillage - CT) on soil C and nutrient stocks in an Oxisol from an Amazonian cerrado following land use change. The study also identified relationships between these stocks and other soil attributes. Carbon, P, K, Ca and Mg stocks, adjusted to the equivalent soil mass in the cerrado (CE), were higher under NT. After adoption of all but one of the NT treatments, C stocks were higher than they were in the other areas we considered. Correlations between C and nutrient stocks showed positive correlations with Ca and Mg under NT due to continuous liming, higher crop residue inputs and lack of soil disturbance, associated with positive correlations with cation exchange capacity (CEC), base saturation and pH. The positive correlation (r = 0.91, p < 0.05) between C stocks and CEC in the CE indicates the important contribution of soil organic matter (SOM) to CEC in tropical soils, although the exchange sites are - under natural conditions - mainly occupied by H and Al. Phosphorus and K stocks showed positive correlations (0.81 and 0.82, respectively) with C stocks in the CE, indicating the direct relationship of P and K with SOM in natural ecosystems. The high spatial variability of P and K fertilizer application may be obscuring these soil nutrient stocks. In this study, the main source of P and K was fertilizer rather than SOM.
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Gusev, Ye M., O. N. Nasonova, L. Ya Dzhogan und E. E. Kovalev. „Scenario forecasting changes in the water balance components of the Olenek and Iindigirka river basins due to possible climate change“. Proceedings of the International Association of Hydrological Sciences 371 (12.06.2015): 13–15. http://dx.doi.org/10.5194/piahs-371-13-2015.
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Abstract. Scenario projections of the dynamics of meteorological characteristics for the basins of the Olenek and Indigirka rivers (the Republic of Sakha) in the XXI century have been obtained for four IPCC global climate change scenarios of SRES family which correspond to specified scenarios of economic, technological, political, and demographic development of human civilization. The projections have been used to calculate scenarios of possible changes in water balance components for the basins under consideration up to the year of 2063. The calculation procedure involves a physically-based model for heat and mass exchange between the land surface and the atmosphere SWAP and climate scenario generator MAGICC/SCENGEN.
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Sun, Xiaofang, Chao Yu, Junbang Wang und Meng Wang. „The Intensity Analysis of Production Living Ecological Land in Shandong Province, China“. Sustainability 12, Nr. 20 (10.10.2020): 8326. http://dx.doi.org/10.3390/su12208326.
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Due to the limitedness of land, the coordinated development of production, living, and ecological (PLE) land is essential for sustainable development. A clear understanding of PLE land change is necessary given the increased human activities, especially in developing regions. This study first reclassified remotely sensed landuse maps in Shandong province into PLE land. Then the spatiotemporal change of PLE land between 2000 and 2015 was analyzed using spatial trajectory and intensity analysis methods. The results show that the rate of PLE land change in the interval of 2000–2005 was the highest, and it kept decreasing during 2005–2010 and 2010–2015. The overall quantity component accounts for more difference than the exchange and shift components for all intervals. At the category level, the largest quantity component of change was PE land loss, followed by LP land gain. LP land gain targeted PE land intensively in each interval. The loss of E land was mainly to PE land in terms of size, and to PL land in terms of intensity. The findings of this study contribute to a deeper understanding of the spatiotemporal transitions of PLE land in Shandong province, which could help policy making for PLE land regulation.
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Marlin, D. „Breathing and bleeding – the problems of being big and running fast“. BSAP Occasional Publication 32 (2004): 31–33. http://dx.doi.org/10.1017/s0263967x00041215.
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The ability to use oxygen during exercise is determined by a combination of the muscle mitochondrial density, the relative proportion of total body mass consisting of locomotory muscle, the gas exchange surface area and the capacity for conduction of oxygen from the gas exchange surface to the muscle cells, i.e. the heart and circulation. Other factors include: the ability to ventilate the lungs to ensure that a high gradient is maintained between the alveolar oxygen tension and that in the pulmonary capillaries to facilitate diffusion; the capillary density within muscle, the size of the muscle cells and the blood oxygen carrying capacity, which is primarily determined by the total blood volume and haemoglobin concentration.In absolute terms, the fastest animal on land is the Cheetah, which can reach speeds of up to 120 kmh. However, the Cheetah is a “sprinter” and can only achieve these speeds for distances of around 200 metres (<10 seconds).
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Siepen, G. L., und J. Westrup. „Communicating vegetation management science to land managers and other stakeholders“. Rangeland Journal 24, Nr. 1 (2002): 170. http://dx.doi.org/10.1071/rj02009.
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Science communication, including extension services, plays a key role in achieving sustainable native vegetation management. One of the pivotal aspects of the debate on sustainable vegetation management is the scientific information underpinning policy-making. In recent years, extension services have shifted their focus from top-down technology transfer to bottom-up participation and empowerment. There has also been a broadening of communication strategies to recognise the range of stakeholders involved in native vegetation management and to encompass environmental concerns. This paper examines the differences between government approaches to extension services to deliver policy and the need for effective communication to address broader science issues that underpin native vegetation management. The importance of knowing the learning styles of the stakeholders involved in native vegetation management is discussed at a time of increasing reliance on mass communication for information exchange and the importance of personal communication to achieve on-ground sustainable management. Critical factors for effective science-management communication are identified such as: (i) undertaking scientific studies (research) with community involvement, acceptance and agreed understanding of project objectives; (ii) realistic community consultation periods; (iii) matching communication channels with stakeholder needs; (iv) combining scientific with local knowledge in an holistic (biophysical and social) approach to understanding an issue; and (v) regional partnerships. These communication factors are considered to be essential to implementing on-ground natural resource management strategies and actions, including those concerned with native vegetation management.
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Heidkamp, Marvin, Andreas Chlond und Felix Ament. „Closing the energy balance using a canopy heat capacity and storage concept – a physically based approach for the land component JSBACHv3.11“. Geoscientific Model Development 11, Nr. 8 (29.08.2018): 3465–79. http://dx.doi.org/10.5194/gmd-11-3465-2018.
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Abstract. Land surface–atmosphere interaction is one of the most important characteristic for understanding the terrestrial climate system, as it determines the exchange fluxes of energy and water between the land and the overlying air mass. In several current climate models, it is common practice to use an unphysical approach to close the surface energy balance within the uppermost soil layer with finite thickness and heat capacity. In this study, a different approach is investigated by means of a physically based estimation of the canopy heat storage (SkIn+). Therefore, as a first step, results of an offline simulation of the land component JSBACH of the Max Planck Institute Earth system model (MPI-ESM) – constrained with atmospheric observations – are compared to energy fluxes and water fluxes derived from eddy covariance measurements observed at the CASES-99 field experiment in Kansas, where shallow vegetation prevails. This comparison of energy and evapotranspiration fluxes with observations at the site-level provides an assessment of the model's capacity to correctly reproduce the diurnal cycle. Following this, a global coupled land–atmosphere experiment is performed using an AMIP (Atmospheric Model Intercomparison Project) type simulation over 30 years to evaluate the regional impact of the SkIn+ scheme on a longer timescale, in particular, with respect to the effect of the canopy heat storage. The results of the offline experiment show that SkIn+ leads to a warming during the day and to a cooling at night relative to the old reference scheme, thereby improving the performance in the representation of the modeled surface fluxes on diurnal timescales. In particular: nocturnal heat releases unrealistically destroying the stable boundary layer disappear and phase errors are removed. On the global scale, for regions with no or low vegetation and a pronounced diurnal cycle, the nocturnal cooling prevails due to the fact that stable conditions at night maintain the delayed response in temperature, whereas the daytime turbulent exchange amplifies it. For the tropics and boreal forests as well as high latitudes, the scheme tends to warm the system.
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Stręk, Żanna, und Karol Noga. „Production value of agricultural land – a factor determining the consolidation of land – case study“. E3S Web of Conferences 171 (2020): 02012. http://dx.doi.org/10.1051/e3sconf/202017102012.
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Land as a means of labour and agricultural production is a very important or even the most important good of a farmer. For centuries spatial structure of Polish rural areas was determined by historical and legal, social and economic, political, economic, technical and demographic conditions. A characteristic feature of land is the fact that it is a part of nature used for plant production but at the same time it is not a product of human labour so it cannot be replaced by a different means of production or its area cannot be increased. Soil quality is one of the most important factors determining potential high income from agricultural activity. Agricultural land quality is expressed as soil class and its suitability for cultivating specific plants or groups of plants – as soil and agricultural complexes. Throughout Poland uniform classification of soil was applied taking into account soil morphology and its physical properties. The study contains elaborate descriptive and cartographic material such as classification maps in the scale equivalent to cadastral maps. In studies concerning spatial and economic phenomena occurring in rural land, respective villages are grouped into larger typological units with respect to similarity of their features. The classification was used in developing a method for the appraisal of land for land consolidation and exchange works. The classification according to land uses can be applied in economic practice better by being expressed as a single number in the form of a productivity ratio rather than a soil quality index. This is the premise underlying the purpose of this paper – calculating the ratio of productivity for cropland and grassland for the needs of identifying villages similar in that respect. The studies were carried out in 116 villages in the county of Łęczna in Lublin voivodeship. Data relating to surface of respective classes of soil was retrieved from the land and buildings register and the calculation of the ratio was based on scores assigned on a 100-point scale.
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Tang, J. Y., und W. J. Riley. „A new top boundary condition for modeling surface diffusive exchange of a generic volatile tracer: theoretical analysis and application to soil evaporation“. Hydrology and Earth System Sciences 17, Nr. 2 (28.02.2013): 873–93. http://dx.doi.org/10.5194/hess-17-873-2013.
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Abstract. We describe a new top boundary condition (TBC) for representing the air–soil diffusive exchange of a generic volatile tracer. This new TBC (1) accounts for the multi-phase flow of a generic tracer; (2) accounts for effects of soil temperature, pH, solubility, sorption, and desorption processes; (3) enables a smooth transition between wet and dry soil conditions; (4) is compatible with the conductance formulation for modeling air–water volatile tracer exchange; and (5) is applicable to site, regional, and global land models. Based on the new TBC, we developed new formulations for bare-soil resistance and corresponding soil evaporation efficiency. The new soil resistance is predicted as the reciprocal of the harmonic sum of two resistances: (1) gaseous and aqueous molecular diffusion and (2) liquid mass flow resulting from the hydraulic pressure gradient between the soil surface and center of the topsoil control volume. We compared the predicted soil evaporation efficiency with those from several field and laboratory soil evaporation measurements and found good agreement with the typically observed two-stage soil evaporation curves. Comparison with the soil evaporation efficiency equation of Lee and Pielke (1992; hereafter LP92) indicates that their equation can overestimate soil evaporation when the atmospheric resistance is low and underestimate soil evaporation when the soil is dry. Using a synthetic inversion experiment, we demonstrated that using inverted soil resistance data from field measurements to derive empirical soil resistance formulations resulted in large uncertainty because (1) the inverted soil resistance data are always severely impacted by measurement error and (2) the derived empirical equation is very sensitive to the number of data points and the assumed functional form of the resistance. We expect the application of our new TBC in land models will provide a consistent representation for the diffusive tracer exchange at the soil–air interface.
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Tang, J. Y., und W. J. Riley. „A new top boundary condition for modeling surface diffusive exchange of a generic volatile tracer: theoretical analysis and application to soil evaporation“. Hydrology and Earth System Sciences Discussions 9, Nr. 10 (22.10.2012): 11941–98. http://dx.doi.org/10.5194/hessd-9-11941-2012.
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Abstract. We describe a new top boundary condition (TBC) for representing the air-soil diffusive exchange of a generic volatile tracer. This new TBC (1) accounts for the multi-phase flow of a generic tracer; (2) accounts for effects of soil temperature, pH, solubility, sorption, and desorption processes; (3) enables a smooth transition between wet and dry soil conditions; (4) is compatible with the conductance formulation for modeling air-water volatile tracer exchange; and (5) is applicable to site, regional, and global land models. Based on the new TBC, we developed new formulations for bare-soil resistance and corresponding soil evaporation efficiency. The new soil resistance is predicted as the reciprocal of the harmonic sum of two resistances: (1) gaseous and aqueous molecular diffusion and (2) liquid mass flow resulting from the hydraulic pressure gradient between the soil surface and center of the topsoil control volume. The resulting soil evaporation efficiency reasonably explains the two-stage soil evaporation curves typically observed in field and laboratory soil evaporation measurements. Comparison with the soil evaporation efficiency equation of Lee and Pielke (1992; hereafter LP92) indicates that their equation can overestimate soil evaporation when the atmospheric resistance is low and underestimate soil evaporation when the soil is dry. Using a synthetic inversion experiment, we demonstrated that using inverted soil resistance data from field measurements to derive empirical soil resistance formulations resulted in large uncertainty because (1) the inverted soil resistance data is always severely impacted by measurement error and (2) the derived empirical equation is very sensitive to the number of data points and the assumed functional form of the resistance. We expect the application of our new TBC in land models will provide a consistent representation for the diffusive tracer exchange at the soil–air interface.
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García-García, David, Isabel Vigo und Mario Trottini. „Water transport among the world ocean basins within the water cycle“. Earth System Dynamics 11, Nr. 4 (07.12.2020): 1089–106. http://dx.doi.org/10.5194/esd-11-1089-2020.
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Abstract. The global water cycle involves water-mass transport on land, in the atmosphere, in the ocean, and among them. Quantification of such transport, especially its time evolution, is essential to identify the footprints of climate change, and it also helps to constrain and improve climatic models. In the ocean, net water-mass transport among the ocean basins is a key process, but it is currently a poorly estimated parameter. We propose a new methodology that incorporates the time-variable gravity observations from the Gravity Recovery and Climate Experiment (GRACE) satellite (2003–2016) to estimate the change in water content; this new approach also overcomes some fundamental limitations of existing methods. We show that the Pacific and Arctic oceans receive an average of 1916 (95 % confidence interval of [1812, 2021]) Gt per month (∼0.72±0.02 Sv) of excess freshwater from the atmosphere and the continents that is discharged into the Atlantic and Indian oceans, where net evaporation minus precipitation returns the water to complete the cycle. This is in contrast to previous GRACE-based studies, where the notion of a see-saw mass exchange between the Pacific and the Atlantic and Indian oceans has been reported. Seasonal climatology as well as the interannual variability of water-mass transport are also reported.
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Maxwell, Reed M., und Norman L. Miller. „Development of a Coupled Land Surface and Groundwater Model“. Journal of Hydrometeorology 6, Nr. 3 (01.06.2005): 233–47. http://dx.doi.org/10.1175/jhm422.1.
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Abstract Traditional land surface models (LSMs) used for numerical weather simulation, climate projection, and as inputs to water management decision support systems, do not treat the LSM lower boundary in a fully process-based fashion. LSMs have evolved from a leaky-bucket approximation to more sophisticated land surface water and energy budget models that typically have a specified bottom layer flux to depict the lowest model layer exchange with deeper aquifers. The LSM lower boundary is often assumed zero flux or the soil moisture content is set to a constant value; an approach that while mass conservative, ignores processes that can alter surface fluxes, runoff, and water quantity and quality. Conversely, groundwater models (GWMs) for saturated and unsaturated water flow, while addressing important features such as subsurface heterogeneity and three-dimensional flow, often have overly simplified upper boundary conditions that ignore soil heating, runoff, snow, and root-zone uptake. In the present study, a state-of-the-art LSM (Common Land Model) and a variably saturated GWM (ParFlow) have been coupled as a single-column model. A set of simulations based on synthetic data and data from the Project for Intercomparison of Land-surface Parameterization Schemes (PILPS), version 2(d), 18-yr dataset from Valdai, Russia, demonstrate the temporal dynamics of this coupled modeling system. The soil moisture and water table depth simulated by the coupled model agree well with the Valdai observations. Differences in prediction between the coupled and uncoupled models demonstrate the effect of a dynamic water table on simulated watershed flow. Comparison of the coupled model predictions with observations indicates certain cold processes such as frozen soil and freeze/thaw processes have an important impact on predicted water table depth. Comparisons of soil moisture, latent heat, sensible heat, temperature, runoff, and predicted groundwater depth between the uncoupled and coupled models demonstrate the need for improved groundwater representation in land surface schemes.
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Abramowitz, Gab, Ray Leuning, Martyn Clark und Andy Pitman. „Evaluating the Performance of Land Surface Models“. Journal of Climate 21, Nr. 21 (01.11.2008): 5468–81. http://dx.doi.org/10.1175/2008jcli2378.1.
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Abstract This paper presents a set of analytical tools to evaluate the performance of three land surface models (LSMs) that are used in global climate models (GCMs). Predictions of the fluxes of sensible heat, latent heat, and net CO2 exchange obtained using process-based LSMs are benchmarked against two statistical models that only use incoming solar radiation, air temperature, and specific humidity as inputs to predict the fluxes. Both are then compared to measured fluxes at several flux stations located on three continents. Parameter sets used for the LSMs include default values used in GCMs for the plant functional type and soil type surrounding each flux station, locally calibrated values, and ensemble sets encompassing combinations of parameters within their respective uncertainty ranges. Performance of the LSMs is found to be generally inferior to that of the statistical models across a wide variety of performance metrics, suggesting that the LSMs underutilize the meteorological information used in their inputs and that model complexity may be hindering accurate prediction. The authors show that model evaluation is purpose specific; good performance in one metric does not guarantee good performance in others. Self-organizing maps are used to divide meteorological “‘forcing space” into distinct regions as a mechanism to identify the conditions under which model bias is greatest. These new techniques will aid modelers to identify the areas of model structure responsible for poor performance.
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Sun, Xiaofang, Guicai Li, Junbang Wang und Meng Wang. „Quantifying the Land Use and Land Cover Changes in the Yellow River Basin while Accounting for Data Errors Based on GlobeLand30 Maps“. Land 10, Nr. 1 (01.01.2021): 31. http://dx.doi.org/10.3390/land10010031.
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Land use and land cover (LULC) change influences many issues such as the climate, ecological environment, and economy. In this study, the LULC transitions in the Yellow River Basin (YRB) were analyzed based on the GlobeLand30 land use data in 2000, 2010, and 2020. The intensity analysis method with hypothetical errors calculation was used, which could explain the deviations from uniform land changes. The strength of the evidence for the deviation was revealed even though the confusion matrixes of the LULC data at each time point for the YRB were unavailable. The results showed that at the interval scale, the land transition rate increased from the first to the second period for all of the upper, middle, and lower reaches. The exchange component was larger than the quantity and shift component, and the gross change was 4.1 times larger than the net change. The size of cultivated land decreased during both intervals. The artificial surfaces gains were active for all three reaches and had strong evidence. A hypothetical error in 93% of the 2000 data and 58% of the 2010 data can explain deviations from uniform transition given woodland gain during 2000–2010 and 2010–2020. Ecological restoration projects such as Grain for Green implemented in 2000 in the upper reaches resulted in the woodland increase.
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Renner, Maik, Sibylle K. Hassler, Theresa Blume, Markus Weiler, Anke Hildebrandt, Marcus Guderle, Stanislaus J. Schymanski und Axel Kleidon. „Dominant controls of transpiration along a hillslope transect inferred from ecohydrological measurements and thermodynamic limits“. Hydrology and Earth System Sciences 20, Nr. 5 (25.05.2016): 2063–83. http://dx.doi.org/10.5194/hess-20-2063-2016.
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Abstract. We combine ecohydrological observations of sap flow and soil moisture with thermodynamically constrained estimates of atmospheric evaporative demand to infer the dominant controls of forest transpiration in complex terrain. We hypothesize that daily variations in transpiration are dominated by variations in atmospheric demand, while site-specific controls, including limiting soil moisture, act on longer timescales. We test these hypotheses with data of a measurement setup consisting of five sites along a valley cross section in Luxembourg. Both hillslopes are covered by forest dominated by European beech (Fagus sylvatica L.). Two independent measurements are used to estimate stand transpiration: (i) sap flow and (ii) diurnal variations in soil moisture, which were used to estimate the daily root water uptake. Atmospheric evaporative demand is estimated through thermodynamically constrained evaporation, which only requires absorbed solar radiation and temperature as input data without any empirical parameters. Both transpiration estimates are strongly correlated to atmospheric demand at the daily timescale. We find that neither vapor pressure deficit nor wind speed add to the explained variance, supporting the idea that they are dependent variables on land–atmosphere exchange and the surface energy budget. Estimated stand transpiration was in a similar range at the north-facing and the south-facing hillslopes despite the different aspect and the largely different stand composition. We identified an inverse relationship between sap flux density and the site-average sapwood area per tree as estimated by the site forest inventories. This suggests that tree hydraulic adaptation can compensate for heterogeneous conditions. However, during dry summer periods differences in topographic factors and stand structure can cause spatially variable transpiration rates. We conclude that absorption of solar radiation at the surface forms a dominant control for turbulent heat and mass exchange and that vegetation across the hillslope adjusts to this constraint at the tree and stand level. These findings should help to improve the description of land-surface–atmosphere exchange at regional scales.
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Lerman, A., und F. T. Mackenzie. „CO<sub>2</sub> air-sea exchange due to calcium carbonate and organic matter storage: pre-industrial and Last Glacial Maximum estimates“. Biogeosciences Discussions 1, Nr. 1 (26.08.2004): 429–95. http://dx.doi.org/10.5194/bgd-1-429-2004.
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Abstract. Release of CO2 from surface ocean water owing to precipitation of CaCO3 and the imbalance between biological production of organic matter and its respiration, and their net removal from surface water to sedimentary storage was studied by means of a model that gives the quotient θ=(CO2 released to the atmosphere)/(CaCO3 precipitated). The surface ocean layer is approximated by a euphotic zone, 50 m thick, that includes the shallower coastal area and open ocean. θ depends on water temperature, CaCO3 and organic carbon mass formed, and atmospheric CO2 concentration. At temperatures between 5 and 25°C, and three atmospheric CO2 pressures – 195 ppmv corresponding to the Last Glacial Maximum, 280 ppmv for the end of pre-industrial time, and 375 ppmv for the present – θ varies from a fraction of 0.38 to 0.79, increasing with decreasing temperature, increasing atmospheric CO2 content, and increasing CaCO3 precipitated mass (up to 45% of the DIC concentration in surface water). For a surface ocean layer that receives input of inorganic and organic carbon from land, the calculated CO2 flux to the atmosphere at the Last Glacial Maximum is 20 to 22×1012 mol/yr and in pre-industrial time it is 45 to 49×1012 mol/yr. In addition to the environmental factors mentioned above, flux to the atmosphere and increase of atmospheric CO2 depend on the thickness of the surface ocean layer. The significance of these fluxes and comparisons with the estimates of other investigators are discussed. Within the imbalanced global carbon cycle, our estimates are in agreement with the conclusions of others that the global ocean prior to anthropogenic emissions of CO2 to the atmosphere was losing carbon, calcium, and total alkalinity owing to precipitation of CaCO3 and consequent emission of CO2. Other pathways of CO2 exchange between the atmosphere and land organic reservoir and rock weathering may reduce the imbalances in the carbon cycle on millenial time scales.
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Sipio, Galgaro, Carli, Greggio, Mantovan und Sukha. „How Different Natural Energy Sources Affect the Shallow Geothermal Suitability in Urban Areas: The South Africa Case Study“. Proceedings 30, Nr. 1 (21.11.2019): 22. http://dx.doi.org/10.3390/proceedings2019030022.
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In recent years, the overall worldwide demand for energy has been increasing due to the constant growth of both global population and industrialization, which is particularly intensifying in emerging countries (China, India, South Africa, Brazil) and recently industrialized ones (i.e., Mexico, Turkey). In this framework, the exploitation of shallow geothermal energy through heat geo-exchange systems, as borehole heat exchangers (closed loop systems) or groundwater systems (open loop systems) coupled with a heat pump (Ground Source Heat Pump—GSHP), is really appealing, due to its versatility and energy efficiency. The heat exchanged with the underground, a reliable and green thermal energy source, is used mainly for heating and cooling of residential, industrial or commercial buildings and greenhouses. Several technologies are available and combinations with other local renewable energy sources are also possible, representing very interesting efficient and environmentally friendly solutions to be adopted in urban areas. The integration of different natural energy sources brings significant advantages, such as the reduction of CO2 emissions, the mitigation of the subsurface urban heat island effect, the minimization of electricity consumption. However, the underground suitability to low enthalpy geothermal systems is strictly related to the climatic, geological, hydrogeological, geothermal and thermophysical properties, typical of the area under investigation. The evaluation of these parameters allows to assess the amount of heat at disposal and the possibility to exchange it. On one hand, it is necessary to select and collect the data related to the factors that better characterize the ground behavior from the point of view of the heat exchange capacity. On the other, it is essential to integrate them in thematic maps created by Geographic Information System (GIS) tools, providing a preliminary evaluation of the territory suitability to geo-exchange and supporting the land use geothermal management both for closed and open loop systems. A preliminary representation of low-enthalpy geothermal resources suitability maps for Johannesburg, Durban and Cape Town, the three main urbanized cities of South Africa, representing the geological and climatic national variability of the country, is here presented. From a methodological point of view, these maps are created by assigning to each value of the descriptive parameters selected (i.e., lithology, type of aquifer, thermal conductivity, average annual air and ground temperature) a corresponding quantitative value, assessing its different attitude for thermal purposes. In this way, one of the first contribution to the suitability of geothermal energy resources in South Africa is obtained.
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Majasalmi, Titta, Stephanie Eisner, Rasmus Astrup, Jonas Fridman und Ryan M. Bright. „An enhanced forest classification scheme for modeling vegetation–climate interactions based on national forest inventory data“. Biogeosciences 15, Nr. 2 (18.01.2018): 399–412. http://dx.doi.org/10.5194/bg-15-399-2018.
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Abstract. Forest management affects the distribution of tree species and the age class of a forest, shaping its overall structure and functioning and in turn the surface–atmosphere exchanges of mass, energy, and momentum. In order to attribute climate effects to anthropogenic activities like forest management, good accounts of forest structure are necessary. Here, using Fennoscandia as a case study, we make use of Fennoscandic National Forest Inventory (NFI) data to systematically classify forest cover into groups of similar aboveground forest structure. An enhanced forest classification scheme and related lookup table (LUT) of key forest structural attributes (i.e., maximum growing season leaf area index (LAImax), basal-area-weighted mean tree height, tree crown length, and total stem volume) was developed, and the classification was applied for multisource NFI (MS-NFI) maps from Norway, Sweden, and Finland. To provide a complete surface representation, our product was integrated with the European Space Agency Climate Change Initiative Land Cover (ESA CCI LC) map of present day land cover (v.2.0.7). Comparison of the ESA LC and our enhanced LC products (https://doi.org/10.21350/7zZEy5w3) showed that forest extent notably (κ = 0.55, accuracy 0.64) differed between the two products. To demonstrate the potential of our enhanced LC product to improve the description of the maximum growing season LAI (LAImax) of managed forests in Fennoscandia, we compared our LAImax map with reference LAImax maps created using the ESA LC product (and related cross-walking table) and PFT-dependent LAImax values used in three leading land models. Comparison of the LAImax maps showed that our product provides a spatially more realistic description of LAImax in managed Fennoscandian forests compared to reference maps. This study presents an approach to account for the transient nature of forest structural attributes due to human intervention in different land models.
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Balawejder, Monika, und Karol Noga. „The influence of the highway route on the development of patchwork of plots“. Journal of Water and Land Development 30, Nr. 1 (01.09.2016): 3–11. http://dx.doi.org/10.1515/jwld-2016-0015.
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AbstractWhen defining the patchwork of plots, based on the literature, it lists the types and subtypes, and given their prevalence in the studied villages. Characterized listed types and subtypes the patchwork of plots the adopted villages crossed by the highway, paying particular attention to the fragmentation of the parcels. Particular attention was paid to the occurrence of the patchwork of the outer of plots for the following reasons: firstly – the presence of plots owners do not reside in the surveyed villages (out-of-village owners) and living in the surveyed villages, but with land in other surveyed villages (local non-resident owners), which is an important issue approximately of plots owners to habitat in the complex work of consolidation and exchange of land; secondly – it allows for adjustment of the boundaries of the village, which destroys the highway without immediate execution merge. This should make such a correction using only the exchange of land; thirdly – crossing the village highway of plots prevents access to out-of-village owners and local non-resident owners when their habitats are located on the opposite side thereof. The study of this problem are designed the patchwork table method to both the external patchwork of plots and internal patchwork of plots. Conducting research in this field mapping method was used to present the occurrence of the external patchwork of plots and the internal patchwork of plots on the cadastral maps.
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McPhee, Miles G., Craig L. Stevens, Inga J. Smith und Natalie J. Robinson. „Turbulent heat transfer as a control of platelet ice growth in supercooled under-ice ocean boundary layers“. Ocean Science 12, Nr. 2 (06.04.2016): 507–15. http://dx.doi.org/10.5194/os-12-507-2016.
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Abstract. Late winter measurements of turbulent quantities in tidally modulated flow under land-fast sea ice near the Erebus Glacier Tongue, McMurdo Sound, Antarctica, identified processes that influence growth at the interface of an ice surface in contact with supercooled seawater. The data show that turbulent heat exchange at the ocean–ice boundary is characterized by the product of friction velocity and (negative) water temperature departure from freezing, analogous to similar results for moderate melting rates in seawater above freezing. Platelet ice growth appears to increase the hydraulic roughness (drag) of fast ice compared with undeformed fast ice without platelets. Platelet growth in supercooled water under thick ice appears to be rate-limited by turbulent heat transfer and that this is a significant factor to be considered in mass transfer at the underside of ice shelves and sea ice in the vicinity of ice shelves.
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McPhee, M. G., C. L. Stevens, I. J. Smith und N. J. Robinson. „Turbulent heat transfer as a control of platelet ice growth in supercool under-ice ocean boundary-layers“. Ocean Science Discussions 12, Nr. 6 (17.11.2015): 2807–29. http://dx.doi.org/10.5194/osd-12-2807-2015.
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Abstract. Late winter measurements of turbulent quantities in tidally modulated flow under land-fast sea ice near the Erebus Glacier Tongue, McMurdo Sound, identified processes that influence growth at the interface of an ice surface in contact with supercool seawater. The data suggest that turbulent heat exchange at the ocean-ice boundary is characterized by the product of friction velocity and (negative) water temperature departure from freezing, analogous to similar results for moderate melting rates in seawater above freezing. Platelet ice growth appears to increase the hydraulic roughness (drag) of fast ice compared with undeformed fast ice without platelets. We hypothesize that platelet growth in supercool water under thick ice is rate-limited by turbulent heat transfer and that this is a significant factor to be considered in mass transfer at the under-side of ice shelves and sea ice in the vicinity of ice shelves.
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Gusev, E. M., O. N. Nasonova, E. A. Shurkhno und L. Y. Dzhogan. „Scenario forecast of changes of the water balance components in the Ob-Irtysh river basin in connection with potential climate change“. Водные ресурсы 46, Nr. 5 (20.09.2019): 463–73. http://dx.doi.org/10.31857/s0321-0596465463-473.
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An intergovernmental group of experts on climate control obtained the forecast options of the dynamics for the weather components of the Ob-Irtysh river basin in the XXI century for four global climatic scenarios of the family “Special Report on Emissions Scenarios” complying with the set scenarios of economic, technological, political, and demographic development of the civilization, which served as the basin for the estimation of the options of possible changes of the water balance components of the specified river basic up to the middle of the XXI century. The calculation technique is based on using the physically based model of heat and mass exchange between the land surface and atmosphere SWAP and the climatic scenarios generator MAGICC/SCENGEN. The changes of the annual flow of the Ob river due to potential global climate changes were compared herein with its natural fluctuations caused by the weather noise.
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Kaisermann, Aurore, Sam Jones, Steven Wohl, Jérôme Ogée und Lisa Wingate. „Nitrogen Fertilization Reduces the Capacity of Soils to Take up Atmospheric Carbonyl Sulphide“. Soil Systems 2, Nr. 4 (15.11.2018): 62. http://dx.doi.org/10.3390/soilsystems2040062.
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Soils are an important carbonyl sulphide (COS) sink. However, they can also act as sources of COS to the atmosphere. Here we demonstrate that variability in the soil COS sink and source strength is strongly linked to the available soil inorganic nitrogen (N) content across a diverse range of biomes in Europe. We revealed in controlled laboratory experiments that a one-off addition of ammonium nitrate systematically decreased the COS uptake rate whilst simultaneously increasing the COS production rate of soils from boreal and temperate sites in Europe. Furthermore, we found strong links between variations in the two gross COS fluxes, microbial biomass, and nitrate and ammonium contents, providing new insights into the mechanisms involved. Our findings provide evidence for how the soil–atmosphere exchange of COS is likely to vary spatially and temporally, a necessary step for constraining the role of soils and land use in the COS mass budget.
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Ghiat, Ikhlas, Hamish R. Mackey und Tareq Al-Ansari. „A Review of Evapotranspiration Measurement Models, Techniques and Methods for Open and Closed Agricultural Field Applications“. Water 13, Nr. 18 (15.09.2021): 2523. http://dx.doi.org/10.3390/w13182523.
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Detailed knowledge of energy and mass fluxes between land and the atmosphere are necessary to monitor the climate of the land and effectively exploit it in growing agricultural commodities. One of the important surface land fluxes is evapotranspiration, which combines the process of evaporation from the soil and that of transpiration from plants, describing the movement of water vapour from the land to the atmosphere. Accurately estimating evapotranspiration in agricultural systems is of high importance for efficient use of water resources and precise irrigation scheduling operations that will lead to improved water use efficiency. This paper reviews the major mechanistic and empirical models for estimating evapotranspiration including the Penman–Monteith, Stanghellini, Priestly–Taylor, and Hargreaves and Samani models. Moreover, the major differences between the models and their underlined assumptions are discussed. The application of these models is also reviewed for both open and closed field mediums and limitations of each model are highlighted. The main parameters affecting evapotranspiration rates in greenhouse settings including aerodynamic resistance, stomatal resistance and intercepted radiation are thoroughly discussed for accurate measurement and consideration in evapotranspiration models. Moreover, this review discusses direct evapotranspiration measurements systems such as eddy covariance and gas exchange systems. Other direct measurements appertaining to specific parameters such as leaf area index and surface leaf temperature and indirect measurements such as remote sensing are also presented, which can be integrated into evapotranspiration models for adaptation depending on climate and physiological characteristics of the growing medium. This review offers important directions for the estimation of evapotranspiration rates depending on the agricultural setting and the available climatological and physiological data, in addition to experimentally based adaptation processes for ET models. It also discusses how accurate evapotranspiration measurements can optimise the energy, water and food nexus.
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Jeltsch-Thömmes, Aurich, Gianna Battaglia, Olivier Cartapanis, Samuel L. Jaccard und Fortunat Joos. „Low terrestrial carbon storage at the Last Glacial Maximum: constraints from multi-proxy data“. Climate of the Past 15, Nr. 2 (30.04.2019): 849–79. http://dx.doi.org/10.5194/cp-15-849-2019.
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Abstract. Past changes in the inventory of carbon stored in vegetation and soils remain uncertain. Earlier studies inferred the increase in the land carbon inventory (Δland) between the Last Glacial Maximum (LGM) and the preindustrial period (PI) based on marine and atmospheric stable carbon isotope reconstructions, with recent estimates yielding 300–400 GtC. Surprisingly, however, earlier studies considered a mass balance for the ocean–atmosphere–land biosphere system only. Notably, these studies neglect carbon exchange with marine sediments, weathering–burial flux imbalances, and the influence of the transient deglacial reorganization on the isotopic budgets. We show this simplification to significantly reduce Δland in simulations using the Bern3D Earth System Model of Intermediate Complexity v.2.0s. We constrain Δland to ∼850 GtC (median estimate; 450 to 1250 GtC ±1SD) by using reconstructed changes in atmospheric δ13C, marine δ13C, deep Pacific carbonate ion concentration, and atmospheric CO2 as observational targets in a Monte Carlo ensemble with half a million members. It is highly unlikely that the land carbon inventory was larger at LGM than PI. Sensitivities of the target variables to changes in individual deglacial carbon cycle processes are established from transient factorial simulations with the Bern3D model. These are used in the Monte Carlo ensemble and provide forcing–response relationships for future model–model and model–data comparisons. Our study demonstrates the importance of ocean–sediment interactions and burial as well as weathering fluxes involving marine organic matter to explain deglacial change and suggests a major upward revision of earlier isotope-based estimates of Δland.
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Saarnio, K., K. Teinilä, S. Saarikoski, S. Carbone, S. Gilardoni, H. Timonen, M. Aurela und R. Hillamo. „Online determination of levoglucosan in ambient aerosols with particle-into-liquid sampler – high-performance anion-exchange chromatography – mass spectrometry (PILS–HPAEC–MS)“. Atmospheric Measurement Techniques 6, Nr. 10 (25.10.2013): 2839–49. http://dx.doi.org/10.5194/amt-6-2839-2013.
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Abstract. Biomass burning, such as domestic heating, agricultural, and wild open-land fires, has a significant influence on the atmosphere at the global and, especially, at the local scale. Levoglucosan has been shown to be a good tracer for biomass burning emissions in atmospheric particulate matter, and several analytical techniques have been presented for the determination of levoglucosan from filter samples. In this paper, a novel combination of a particle-into-liquid sampler (PILS) to a high-performance anion-exchange chromatograph (HPAEC) with the detection by a mass spectrometer (MS) is presented for the online analysis of levoglucosan in ambient particles. The PILS–HPAEC–MS technique enables a fast online analysis of levoglucosan from the particulate samples. The method was tested at an urban background station in Helsinki, Finland, in winter 2011. A comparison with simultaneous levoglucosan measurements from filter samples by the HPAEC–MS was performed and it showed a good agreement between the online and offline methods. Additionally, the online levoglucosan data were compared with the biomass burning tracer fragments measured by a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). As there were no local biomass burning sources close to the measurement station, online levoglucosan measurements revealed that most of the particles from biomass burning were either regionally distributed or long-range transported in the urban background of Helsinki. The average levoglucosan concentrations were relatively low (average 0.083 μg m−3) during the measurement campaign. The highest concentration peak measured for levoglucosan (1.4 μg m−3) seemed to originate from biomass burning in the Baltic countries, likely in Estonia, that was transported to Helsinki.
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Saarnio, K., K. Teinilä, S. Saarikoski, S. Carbone, S. Gilardoni, H. Timonen, M. Aurela und R. Hillamo. „Online determination of levoglucosan in ambient aerosols with Particle-into-Liquid Sampler – High-Performance Anion-Exchange Chromatography – Mass Spectrometry (PILS–HPAEC–MS)“. Atmospheric Measurement Techniques Discussions 6, Nr. 3 (19.06.2013): 5495–527. http://dx.doi.org/10.5194/amtd-6-5495-2013.
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Abstract. Biomass burning, such as domestic heating, agricultural, and wild open-land fires, has a significant influence on the atmosphere at the global and, especially, at the local scale. Levoglucosan has been shown to be a good tracer for biomass burning emissions in atmospheric particulate matter and several analytical techniques have been presented for the determination of levoglucosan from filter samples. In this paper, a novel combination of a Particle-into-Liquid Sampler (PILS) to a high-performance anion-exchange chromatograph (HPAEC) with the detection by a mass spectrometer (MS) is presented for the online analysis of levoglucosan in ambient particles. The PILS–HPAEC–MS technique enables a fast online analysis of levoglucosan from the particulate samples. The method was tested at an urban background station in Helsinki, Finland, in winter 2011. A comparison with simultaneous levoglucosan measurements from filter samples by the HPAEC–MS was performed and it showed a good agreement between the online and offline methods. Additionally, the online levoglucosan data were compared with the biomass burning tracer fragments measured by a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS). As there were no local biomass burning sources close to the measurement station, online levoglucosan measurements revealed that most of the particles from biomass burning were either regionally distributed or long-range transported in the urban background of Helsinki. The average levoglucosan concentrations were relatively low (average 0.083 μg m−3) during the measurement campaign. The highest concentration peak measured for levoglucosan (1.4 μg m−3) seemed to originate from biomass burning in Eastern Europe, likely in Estonia, that was transported to Helsinki.
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Hara, Susumu. „Systematization of Shock Response Control Based on Momentum Exchange and Energy Exchange and Its Application to Lunar/Planetary Spacecraft“. Impact 2019, Nr. 10 (30.12.2019): 73–75. http://dx.doi.org/10.21820/23987073.2019.10.73.
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Professor Susumu Hara is based at the Department of Aerospace Engineering, Nagoya University in Japan explains that when the Mars rover Opportunity was set to land on that planet in the first weeks of 2004, onlookers held their breath as it dropped from orbit and hurtled toward the red surface. 'Any failure in the calculations or landing systems would mean a harder than expected impact,' he highlights. 'The impacts sustained by a rover such as Opportunity can derail a mission before it even starts, damaging cargo or vital systems required to complete the mission.' Impacts occur during landing but also as the craft enters the atmosphere, when it makes sudden moves, while it is on surface or when debris strikes it. 'Therefore, a system and materials to protect a craft are vital,' outlines Hara. 'Surprisingly, the solutions to this problem are not sophisticated. In fact, most craft still employ devices resembling automobile bumpers, which absorb the energy from an impact by crumpling under the force of said impact.' Unfortunately, these cannot be reused, even during testing phases a new prototype is required after every single test run. Recent missions also employed techniques like airbags or sky cranes. While successful they too have drawbacks. 'Airbags create huge rebounds which can jostle the craft and the contents inside while sky cranes are extremely costly to develop,' Hara says. For this reason, he is dedicated to designing a new highly reliable and cost-effective shock control mechanism.
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Hung, Jacqueline K. Y., und Paul Treitz. „Environmental land-cover classification for integrated watershed studies: Cape Bounty, Melville Island, Nunavut“. Arctic Science 6, Nr. 4 (01.12.2020): 404–22. http://dx.doi.org/10.1139/as-2019-0029.
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Thematic maps developed from remote sensing data are extremely useful for designing intensive field studies, particularly for large areas that are logistically challenging to access. The integrated watershed studies at the Cape Bounty Arctic Watershed Observatory (CBAWO), Melville Island, Nunavut, rely heavily on land cover for establishing sampling locations regardless of the type of research being conducted (e.g., permafrost degradation, greenhouse gas exchange, surface water chemistry, etc.). Here, we present an environmental land-cover classification of the CBAWO that was developed through an iterative process employing parametric and non-parametric classification algorithms applied to WorldView-2 satellite data and topographic variables. The support vector machine classification of eight-band WorldView-2 spectral data and a topographic wetness index produced the highest classification accuracy for eight land-cover classes (overall classification accuracy: 90.7%; Kappa coefficient (κ): 0.89). This analysis also provided a more precise classification scheme, particularly in the context of the relationship between vegetation type and moisture regime. The environmental land-cover classification derived will better inform future integrated studies of the watershed and allow for upscaling of site-level characteristics to the watershed-scale using the updated vegetation classes.
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Matthiessen, Jens, Jochen Knies, Christoph Vogt und Ruediger Stein. „Pliocene palaeoceanography of the Arctic Ocean and subarctic seas“. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 367, Nr. 1886 (16.10.2008): 21–48. http://dx.doi.org/10.1098/rsta.2008.0203.
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The Pliocene is important in the geological evolution of the high northern latitudes. It marks the transition from restricted local- to extensive regional-scale glaciations on the circum-Arctic continents between 3.6 and 2.4 Ma. Since the Arctic Ocean is an almost land-locked basin, tectonic activity and sea-level fluctuations controlled the geometry of ocean gateways and continental drainage systems, and exerted a major influence on the formation of continental ice sheets, the distribution of river run-off, and the circulation and water mass characteristics in the Arctic Ocean. The effect of a water mass exchange restricted to the Bering and Fram Straits on the oceanography is unknown, but modelling experiments suggest that this must have influenced the Atlantic meridional overturning circulation. Cold conditions associated with perennial sea-ice cover might have prevailed in the central Arctic Ocean throughout the Pliocene, whereas colder periods alternated with warmer seasonally ice-free periods in the marginal areas. The most pronounced oceanographic change occurred in the Mid-Pliocene when the circulation through the Bering Strait reversed and low-salinity waters increasingly flowed from the North Pacific into the Arctic Ocean. The excess freshwater supply might have facilitated sea-ice formation and contributed to a decrease in the Atlantic overturning circulation.
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Vinogradova, Nadya T., Rui M. Ponte, Katherine J. Quinn, Mark E. Tamisiea, Jean-Michel Campin und James L. Davis. „Dynamic Adjustment of the Ocean Circulation to Self-Attraction and Loading Effects“. Journal of Physical Oceanography 45, Nr. 3 (März 2015): 678–89. http://dx.doi.org/10.1175/jpo-d-14-0150.1.
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AbstractThe oceanic response to surface loading, such as that related to atmospheric pressure, freshwater exchange, and changes in the gravity field, is essential to our understanding of sea level variability. In particular, so-called self-attraction and loading (SAL) effects caused by the redistribution of mass within the land–atmosphere–ocean system can have a measurable impact on sea level. In this study, the nature of SAL-induced variability in sea level is examined in terms of its equilibrium (static) and nonequilibrium (dynamic) components, using a general circulation model that implicitly includes the physics of SAL. The additional SAL forcing is derived by decomposing ocean mass anomalies into spherical harmonics and then applying Love numbers to infer associated crustal displacements and gravitational shifts. This implementation of SAL physics incurs only a relatively small computational cost. Effects of SAL on sea level amount to about 10% of the applied surface loading on average but depend strongly on location. The dynamic component exhibits large-scale basinwide patterns, with considerable contributions from subweekly time scales. Departures from equilibrium decrease toward longer time scales but are not totally negligible in many places. Ocean modeling studies should benefit from using a dynamical implementation of SAL as used here.