bluuebunny/crossref_metadata_2025 huggingface dataset:
A weather regime characterisation of winter biomass aerosol transport in southern Africa
Authors: Gaetani Marco , Alvarez Castro Maria del Carmen , Flamant Cyrille , Pohl Benjamin , Formenti Paola
Published: March 2020

Atmospheric dynamics over southern Africa and South Atlantic is dominated by complex aerosol-radiation-cloud interactions, and the characterisation of the tropospheric distribution of aerosols is essential for the full understanding of these interactions.

During austral winter, a compact low cloud deck over South Atlantic contrasts clear sky over southern Africa, where forest fires triggered by dry conditions emit large amount of biomass burning aerosols in the free troposphere. Most of the aerosol burden crosses the Tropical Atlantic embedded in the tropical easterly flow. However, mid-latitude synoptic disturbances can deflect part of the aerosols from the main transport path towards southern extra-tropics.

In this study, a characterisation of the synoptic variability controlling biomass burning aerosols in southern Africa and South Atlantic during austral winter is presented. By analysing ECMWF reanalysis data, a weather regime classification of the region is constructed and used to characterise the aerosol distribution in the period 2003-2017. Results show three southward transport paths, each associated with a specific circulation regime.

 
Deriving anthropogenic CO2 emissions for combustion by application of the emission-ratio method to TROPOMI/S5P NO2 emission data.
Authors: de Laat Jos , van der A Ronald
Published: March 2020

Anthropogenic CO2 and NO2 emissions from combustion processes usually have the same sources but different emission ratios. Because of their similar sources, combustion emissions of CO2 and NO2 are correlated in space and time. Or in other words: combustion emissions of NO2 will generally be accompanied by CO2 emissions, and vice versa.

This concept can be used for converting satellite-based emissions of NO2 into CO2 emissions by multiplying known emission ratios of CO2 over NO2 from established emission databases with satellite-derived NO2 emissions.

As part of the H2020 CHE project (“CO2 Human Emissions”) we have applied this method to TROPOMI/S5P NO2 emission data and “bottom-up” emission databases from Dutch TNO. TROPOMI/S5P emissions using the inversion algorithm DECSO were derived for the Iberian Peninsula in Europe and an area over South America.

We find that, after accounting for naturally occurring soil NOx emissions, the spatial distribution of DECSO-TROPOMI based CO2 emissions over the Iberian Peninsula and the South America region overall are very realistic, and within uncertainties CO2 emissions budgets from both methods are not dissimilar.

We will also present and discuss some additional aspects and uncertainties of this ratio-method, including the influence of uncertainties in the TNO bottom-up emission database, like inter-country differences, and the relevance of applying emission ratios representative for the same time period as the TROPOMI/S5P measurements. We will also provide some recommendations for further improving this method.

Overall, at minimum this method appears to provide a “sanity check” for bottom-up (reported) CO2 emissions, but potentially more than that, also evidenced by several new satellite mission proposals to combine direct measurements of CO2 with direct measurements of NO2 from the same satellite platform.
Permeability tensors of three-dimensional numerically grown geomechanical discrete fracture networks
Authors: Paluszny Adriana , Thomas Robin N , Zimmerman Robert W
Published: March 2020

The mechanics of fracture propagation and interaction influence the growth and permeability of developing fracture networks. A set of initial flaws grows quasi-statically in response to a remote tensile stress. A finite element, stress intensity factor-based approach grows these flaws into non-planar three-dimensional discrete fracture networks (GDFNs). Their extension and growth angle is a function of local stress intensity factors along a fracture tip. Stress concentration increase when proximal fractures are aligned, and decreases when they are sub-coplanar. These interactions can result in the reactivation of fractures that were initially inactive, and the arrest of fractures that become entrapped by proximal growing fractures. Interaction can cause growth away from an intersection front between two fractures, resulting in evolving fracture patterns that become non-uniform and non-planar, forming dense networks. These GDFNs provide representations of subsurface networks that numerically model the physical process of concurrent fracture growth. Permeability tensors of the geomechanical 3D networks are computed, assuming Darcy flow. Growth influences apertures, and in turn, the hydraulic properties of the network. GDFNs provide a promising way to model subsurface fracture networks, and their related hydro-mechanical processes, where fracture mechanics is the primary influence on the geometric and hydraulic properties of the networks.
Limits to natural disasters management: the influence of human behavior
Authors: Aerts Jeroen
Published: March 2020

Despite billions of dollars of investments in disaster risk reduction (DRR), data over the period 1994- 2013 show natural disasters caused 1.35 million lives. Science respond with more timely and accurate information on the dynamics of risk and vulnerability of natural hazards, such as floods. This information is essential for designing and implementing effective climate change adaptation and DRR policies. However, how much do we really know about how the main agents in DRR (individuals, businesses, government, NGO) use this data? How do agents behave before, during, and after a disaster, since this can dramatically affect the impact and recovery time. Since existing risk assessment methods rarely include this critical ‘behavioral adaptation’ factor, significant progress has been made in the scientific community to address human adaptation activities (development of flood protection, reservoir operations, land management practices) in physically based risk models.

This presentation gives an historic overview of the most important developments in DRR science for flood risk. Traditional risk methods integrate vulnerability and adaptation using a ‘top- down’ scenario approach, where climate change, socio economic trends and adaptation are treated as external forcing to a physically based risk model (e.g. hydrological or storm surge model). Vulnerability research has made significant steps in identifying the relevant vulnerability indicators, but has not yet provided the necessary tools to dynamically integrate vulnerability in flood risk models.

However, recent research show novel methods to integrate human adaptive behavior with flood risk models. By integrating behavioral adaptation dynamics in Agent Based Risk Models, may lead to a more realistic characterization of the risks and improved assessment of the effectiveness of risk management strategies and investments. With these improved methods, it is also shown that in the coming decades, human behavior is an important driver to flood risk projections as compared to other drivers, such as climate change. This presentation shows how these recent innovations for flood risk assessment provides novel insight for flood risk management policies.
Predicting atmospheric optical properties for radiative transfer computations using neural networks
Authors: Veerman Menno , Pincus Robert , van Leeuwen Caspar , Podareanu Damian , Stoffer Robin , van Heerwaarden Chiel
Published: March 2020

A fast and accurate treatment of radiation in meteorological models is essential for high quality simulations of the atmosphere. Despite our good understanding of the processes governing the transfer of radiation, full radiative transfer solvers are computationally extremely expensive. In this study, we use machine learning to accelerate the optical properties calculations of the Rapid Radiative Transfer Models for General circulation model applications - Parallel (RRTMGP). These optical properties control the absorption, scattering and emission of radiation within each grid cell. We train multiple neural networks that get as input the pressure, temperature and concentrations of water vapour and ozone of each grid cell and together predict all 224 or 256 quadrature points of each optical property. All networks are multilayer perceptrons and we test various network sizes to assess the trade-off between the accuracy of a neural network and its computational costs. We train two different sets of neural networks. The first set (generic) is trained for a wide range of atmospheric conditions, based on the profiles chosen by the Radiative Forcing Model Intercomparison Project (RFMIP). The second set (case-specific) is trained only for the range in temperature, pressure and moisture found in one large-eddy simulation based on a case with shallow convection over a vegetated surface. This case-specific set is used to explore the possible performance gains of case-specific tuning.

Most neural networks are able to predict the optical properties with high accuracy. Using a network with 2 hidden layers of 64 neurons, predicted optical depths in the longwave spectrum are highly accurate (R2 > 0.99). Similar accuracies are achieved for the other optical properties. Subsequently, we take a set of 100 atmospheric profiles and calculate profiles of longwave and shortwave radiative fluxes based on the optical properties predicted by the neural networks. Compared to fluxes based on the optical properties computed by RRTMGP, the downwelling longwave fluxes have errors within 0.5 W m-2 (<1%) and an average error of -0.011 W m-2 at the surface. The downwelling shortwave fluxes have an average error of -0.0013 W m-2 at the surface. Using Intel’s Math Kernel Library’s (MKL) BLAS routines to accelerate matrix multiplications, our implementation of the neural networks in RRTMGP is about 4 times faster than the original optical properties calculations. It can thus be concluded that neural networks are able to emulate the calculation of optical properties with high accuracy and computational speed.
Partitioning the Uncertainty of Ensemble Projections of Global Glacier Mass Change
Authors: Marzeion Ben , Hock Regine , Anderson Brian , Bliss Andrew , Champollion Nicolas , Fujita Koji , Huss Matthias , Immerzeel Walter , Kraaijenbrink Philip , Malles Jan-Hendrik , Maussion Fabien , Radic Valentina , Rounce David , Sakai Akiko , Shannon Sarah , van de Wal Roderik , Zekollari Harry
Published: March 2020

Glacier mass loss is recognized as a significant contributor to current sea-level rise. However, large uncertainties remain in projections of glacier mass loss on global and regional scales. We present an ensemble of 279 global-scale glacier mass and area change projections for the 21st century based on eleven glacier models using up to ten General Circulation Models (GCMs) and four Representative Concentration Pathways (RCPs) as boundary conditions. We partition the total uncertainty into the individual contributions caused by glacier models, GCMs, RCPs, and natural variability. We find that emission scenario uncertainty is growing throughout the 21st century, and is the largest source of uncertainty by 2100. The relative importance of glacier model uncertainty decreases over time, but it is the greatest source of uncertainty until the middle of this century. The projection uncertainty associated with natural variability is small on the global scale but has strong effects on small regional scales. The projected global mass loss by 2100 relative to 2015 (75±64 mm sea-level equivalent (SLE) for RCP2.6, 165±98 mm SLE for RCP8.5) is lower than, but within the uncertainty range of previous projections.
Construction of a Light Emitting Diode Chamber for Measurement of Gas Exchange in the Plant Ecosystem
Authors: Shin Taehwan , Jeong Seungtaek , Ko Jonghan
Published: March 2020

Abstract: A canopy chamber system is useful to measure gas exchanges in the plant ecosystem. A transparent chamber has been generally used to measure canopy fluxes in the field, such that the light source for photosynthesis depends on the solar radiation. However, it is challenging to measure stable canopy fluxes in the field due to changeable solar radiation conditions in nature. In this study, we constructed a new chamber system to measure canopy fluxes using a Light Emitting Diode (LED) as a light source. Upon the construction, we aim to measure quantitative gas exchanges to estimate the amount of photosynthesis and evapotranspiration using the constructed chamber system in crop fields. While diverse chamber systems have been developed to measure canopy gas exchanges so far, no attempt has been made to create such an LED chamber system according to our best knowledge. The new chamber system was composed of a chamber, LEDs with a maximum power capacity of 1,800W, a water pump for cooling, and a gas analyzer (LI-850, LI-COR, USA). This LED chamber system can estimate the amount of photosynthesis and evapotranspiration rate of plants by measuring both CO2 and H2O fluxes in the ecosystem. These measurements can contribute to the practical assessment of crop productivity as well as scientific advancement in plant ecophysiology.

 

Keywords: Crop, evapotranspiration, gas exchange, LED, chamber, photosynthesis

 

Acknowledgement: This research was supported by "Cooperative Research Program for Agriculture Science & Technology Development (Project No. PJ013841022018)" from Rural Development Administration, Republic of Korea.
Monitoring CO emissions from urban districts in Mexico City using about 2 years of TROPOMI CO observations
Authors: Borsdorff Tobias , Garcia Reynoso Agustin , Stremme Wolfgang , aan de Brugh Joost , Grutter Michel , Landgraf Jochen
Published: March 2020

The Tropospheric Monitoring Instrument (TROPOMI) on ESA Copernicus Sentinel-5P satellite (S5-P) monitors the total column concentration of carbon monoxide (CO) as one of its primary targets.  In this study, we present an approach to analyze the large amount of TROPOMI CO data and to estimate urban emissions on sub-city scales for metropolises like Mexico City. The results demonstrate the advance in using TROPOMI observations for monitoring regional air quality. To this end, we analyze about two years of TROPOMI CO measurements with 551 overpasses over Mexico City using tracer simulations of the regional Weather Research and Forecasting (WRF) model. Ten separate CO tracers for emissions of the districts Tula, Pachuca, Tulancingo, Ciudad de Mexico, Toluca, CDMX, Cuernavaca, Cuautla, Tlaxcala, and Puebla are used to conclude on the emissions of different urban districts. A regularized source inversion minimizes the difference with respect to a prior emission estimate. Here, the degree of freedom of the inferred sources is a powerful tool to filter on measurement information and forward model errors e.g. due to erroneous wind fields. We compare the estimated emissions with those of the national inventory ``Inventario Nacional de Emisiones de Contaminantes Criterio'' (INEM) multiplied by 0.48 to make it applicable for the years 2017 to 2019. Overall, TROPOMI confirms the total INEM CO emissions form the area but indicates clear differences in relative distribution of the emissions between the districts. For example, TROPOMI yields 0.11 Tg/yr and 0.10 Tg/yr CO emissions for the urban districts Tula and Pachuca in the North of Mexico City, which exceeds the INEM emissions of <0.008 Tg/yr. Also, for the central part of Mexico City (CDMX) the TROPOMI estimate with 0.14 Tg/yr differs significantly from the inventory with 0.25 Tg/yr. Moreover, we found that the retrieved emissions for CDMX and Ciudad de Mexico follow a clear weakly cycle with a minimum during the weekend in agreement with ground-based in situ measurements of the ``Secretaria del Medio Ambiente'' (SEDEMA) and column measurements of a Fourier Transform Spectrometer in Mexico City operated by the National Autonomous University of Mexico (UNAM). To improve further the TROPOMI CO data exploitation, our study clearly indicates the need for improvements of regional models like WRF, in particular with respect to the prediction of the local wind fields.
Multiple 6C-station Huddle Test in Fürstenfeldbruck, Germany
Authors: Izgi Gizem , Donner Stefanie , Bernauer Felix , Vollmer Daniel , Stammler Klaus , Hoffmann Mathias , Eibl Eva P.S.
Published: March 2020

Rotational motions play a key role in measuring seismic wavefield properties. To fully understand and describe the behavior of seismic waves, both translational and rotational components should be properly investigated. Portable blueSeis-3A (iXblue) sensors allow to measure 3 components of rotational motions with high sensitivity in a frequency range from 0.001 Hz to 50 Hz.

A huddle test was performed in Fürstenfeldbruck, Germany by the University of Potsdam in collaboration with the Ludwig-Maximilians University of Munich (LMU) and Federal Institute for Geosciences and Natural Resources (BGR) between 26 of August and 02 of September 2019, in order to further investigate the performance of multiple rotational instruments in combination with seismometers. Within the scope of this test, 5 rotational and 3 translational sensors were deployed on the basement of the observatory on decoupled plinth. Our preliminary results show good correlation between all components and rotational sensors. To investigate the coherent noise between sensors, we applied a 50 Hz low-pass filter and 100 Hz sampling rate. To better illustrate, probabilistic power spectral densities and spectrograms have been created. In general, we will discuss the reliability of the data recorded by rotational sensors for further investigations.

 
Numerical modelling of tectonic underplating in accretionary wedges
Authors: Ruh Jonas B.
Published: March 2020

Accretionary wedge systems result from scraping clastic sedimentary sequences off a descending oceanic plate at subduction zones. Sediments covering the incoming, subducting oceanic plate may be accreted at the wedge front forming a typical imbricate fan. Buried parts of the stratigraphic sequence may underthrust the wedge body and get subsequently accreted at its base (underplating) or even descend further into the mantle. Tectonic underplating requires a step-down of the major décollement horizon representing in fact the subduction plate interface. Intense underplating at the rear of accretionary wedges ultimately leads to antiformal stacking and, in combination of surface erosion, to the uplift of sediments formerly accreted at the base of wedges. In the present study, I try to determine and quantify the main features leading to tectonic underplating and subsequent uplift of underthrust incoming sediments at subduction zones. To do so, a numerical model is set up defined by a downgoing rigid plate, an overlying sedimentary sequence and a rigid backstop resulting in sediment accretion. The implementation of two weak décollement layers allows for the potential development of tectonic underplating. Tested parameters for the tectonic evolution of such systems include décollement strength, surface erosion, elastic stiffness of the downgoing plate and geometry of the rigid backstop. The applied numerical code is based on the finite difference marker-in-cell technique with a visco-elasto-plastic rheology. Results indicate that underplating is intensified when i) the stratigraphically lower décollement is strengthened with respect to the upper one, ii) surface erosion is increased, or iii) the downgoing plate becomes stiffer. Modelling results are compared to natural cases of accrretionary wedges where sediments have been underplated (and eventually exhumed) as in the Makran, the Franciscan, or the Appalachians.
Uncertainties in Chi analysis: implications for drainage network and divide stability
Authors: Turowski Jens , Schwanghart Wolfgang , Huppert Kim , Masteller Claire
Published: March 2020

In recent years, Chi analysis has become an important tool for tectonic and geomorphic analyses of longitudinal and planform patterns of river networks. Predicated on the commonly observed inverse scaling between drainage area and slope in rivers and integrating drainage area, the metric Chi has several advantages over other topographic metrics used to describe river long profiles. For a steady state river, Chi scales linearly with elevation, simplifying visual interpretation and further analysis. As an integral property, it also reduces scatter in noisy topographic data. In addition, comparison of computed Chi values to the steady state assumption are a popular tool to determine the stability of river networks and mobility of drainage divides. In this application it is thought that the drainage divide is mobile when Chi values are unequal at adjacent channel heads when integrated from a common base level. These differences in Chi are now frequently used to map mobile and stationary divides and to interpret their spatial patterns in terms of tectonic forcing.

 

As the interpretation of divide mobility relies on a difference in Chi values across the divide, the question arises: how magnitude of cross-divide differences in Chi is necessary for a statistically significant result, given inherent uncertainty in calculations of Chi and the topographic data from which they are derived? Currently, uncertainties in Chi have not been formally evaluated. As such, it remains unclear how robust measurements of differential cross-divide Chi are as a proxy for interpreting drainage divide mobility. Here, we argue that uncertainties in differential cross-divide Chi depend on the location and length of the drainage divide. In a discrete representation of topography, we identify two sources of error. The first source of error can arise if a pixel is incorrectly assigned to a catchment on one side of the divide due either to error in the topographic data or uncertainty in the delineation of drainage area from a digital elevation model (DEM). The second source of error arises because the divide is a linear feature, which cuts across individual pixels in a gridded DEM. Thus, a pixel at the boundary of one designated catchment typically contains area that should drain to its neighboring catchment. We develop an analytical description of these sources of error and show that uncertainties in differential cross-divide Chi can be of the same order as the cross-divide difference in Chi itself. The results from the analytical solution are consistent with a numerical assessment of Chi uncertainties from flow routing on DEMs using multiple flow directions. We discuss scaling with drainage area, and the implications for drainage network mobility using type examples.
A compositional formulation for multiphase multicomponent reactive transport modelling of highly coupled systems
Authors: Seigneur Nicolas , Mayer K. Ulrich
Published: March 2020

In certain reactive transport applications, strong coupling between geochemical reactions and hydrodynamics exists. Dissolution and precipitation of minerals, such as the conversion between gypsum and anhydrite [1] or the precipitation of nesquehonite during CO2 sequestration [2], as well as gas bubble formation [3] are geochemical processes which modify the multiphase flow dynamics, with direct feedback on reactive transport processes. In addition, heat generation induced by sulphide mineral oxidation can lead to significant increases in temperature [4], impacting flow, transport and geochemical reactions. In these instances, commonly used reactive transport modelling approaches, which rely on decoupling flow and reactive transport processes, have limitations. For density dependent or two-phase flow problems in the presence of a gas phase, the coupling between flow and reactive transport can be accounted for through a Picard iterative approach [3,5,6]. However, this approach is computationally expensive, involving the solution of nonlinear problems multiple times during each timestep, and convergence properties are often poor. More recently, a weak explicit coupling approach was developed to capture the impact of chemistry on flow by integrating water as a component and perform a volume balance calculation [7]. In the current work, a compositional approach is implemented into MIN3P-THCm, in which the flow variables (pressure, density) are expressed based on mass variables. Hence, this global implicit approach does not require solving the flow problem, but instead integrates groundwater flow processes directly into the reactive transport equations. We show that this approach yields very similar results to the commonly used approaches for single and two-phase flow. Finally, we show that, in highly coupled systems, not considering these coupled effects may lead to significant errors in simulating system evolution, highlighting the benefits of the newly developed approach.

 

[1] Jowett, Cathles & Davis (1993). AAPG Bulletin, 77(3), 402-413.

[2] Harrison, Dipple, Power & Mayer (2015). Geochimica et cosmochimica Acta, 148, 477-495.

[3] Amos and Mayer (2006). Journal of contaminant hydrology, 87(1-2), 123-154.

[4] Lefebvre, Hockley, Smolensky & Gélinas (2001). Journal of contaminant hydrology, 52(1-4), 137-164.

[5] Henderson, Mayer, Parker, & Al (2009). Journal of contaminant hydrology, 106(3-4), 195-211.

[6] Sin, Lagneau and Corvisier (2017). Advances in Water Resources, 100, 62-77.

[7] Seigneur, Lagneau, Corvisier & Dauzères (2018). Advances in Water Resources 122, 355-366.
Correcting for Model Changes in Statistical Post-Processing - An approach based on Response Theory
Authors: Demaeyer Jonathan , Vannitsem Stéphane
Published: March 2020

For most statistical post-processing schemes used to correct weather forecasts, changes to the forecast model induce a considerable reforcasting effort. We present a new approach based on response theory to cope with slight model change. In this framework, the model change is seen as a perturbation of the original forecast model. The response theory allows then to evaluate the variation induced on the averages involved in the statistical post-processing, provided that the magnitude of this perturbation is not too large.

This approach is studied in the context of a simple quasi-geostrophic model. It provides a proof-of-concept of the potential performances of response theory in a chaotic system. The parameters of the statistical post-processing used - an Error-in-Variables Model Output Statistics (EVMOS) - are appropriately corrected when facing a model change. The potential application in a more operational environment is also discussed.
Sustainability of the Lower Mekong River under human impact: A freshwater ecosystem health investigation
Authors: Mohammed Ibrahim , Bolten John , Souter Nicholas , Shaad Kashif , Vollmer Derek
Published: March 2020

Understanding the impacts of human activity on the environment is critical to water resources planning and ecosystem services sustainability.  The goal of this work is to develop decision making and support tools for natural resources conservation and assessment at the Lower Mekong River basin by leveraging satellite observations of Earth, physical hydrological modeling (doi:10.3390/rs10060885), and freshwater health index framework (doi: 10.1016/j.scitotenv.2018.01.040).  The approach adopted in this work relied on a comprehensive suite of hydrological data products and a regional hydrological decision support system application for the Lower Mekong River basin compiled and developed to improve water accounting and floodplain management.  The social-ecological framework named the freshwater health index (FHI) takes account of the interplay between governance, stakeholders, freshwater ecosystems and the ecosystems services they provide.  Various dam reservoir scenarios have been examined based on stakeholder engagement to enhance the results of the integrative social and ecological nature of fresh waters at the Srepok, Sesan, and Sekong (3S) River basins of the Lower Mekong.  Preliminary results represented by ecosystem vitality indicator has corroborated seasonal flow patterns change in response to water storage capacity increase.  For instance, current modeled reservoirs at the 3S River basin exhibit a deviation from natural flow decrease of 10% when compared with baseline reservoirs.  Governance and Stakeholders role has been found critical to the health of the 3S freshwater ecosystem.  The approach methodology utilized in this work employing the integration of satellite earth observation data and hydrological modeling to investigate ecosystem freshwater health is applicable on a global scale.  This work is part of an ongoing research partnership work between the National Aeronautical and Space Agency (NASA) and the Conservation International (CI) dedicated to improving natural resources assessment for conservation and sustainable management.
Challenges in ocean modelling and data assimilation for CMEMS
Authors: Bell Mike
Published: March 2020

The ambition of CMEMS is to be the primary source of information for monitoring and prediction of the physical and bio-geochemical properties of the marine environment, both in the global deep ocean and in European coastal waters. This requires that the teams developing CMEMS identify and address several key scientific and technical challenges. Some challenges relate to the ocean model used to generate CMEMS products. For example to ensure that it simulates the most important aspects of the flow as faithfully as other ocean models and that it is able to perform efficiently on relevant High Performance Computer (HPC) systems. Some challenges relate to the data assimilation. For example to ensure that the ocean re-analyses are not compromised by problems caused by biases in the ocean model and to develop more effective collaboration within the team of data assimilation developers. Other challenges relate to biogeochemistry (BGC). For example to develop monitoring systems sufficient to support the validation and development of the BGC models, and suitable systems for joint assimilation of physical and BGC measurements. The presentation will focus on illustrating and discussing these challenges.
Assessing the Influences of Large-Scale Disturbance on Sedimentary Marine Carbon Stores
Authors: Black Kirsty , Austin William , Norkko Joanna
Published: March 2020

Shelf and coastal seas hold vast quantities of sedimentary carbon which contribute to atmospheric carbon dioxide removal and long-term carbon storage. However, the stability and resilience of this key component of global natural capital remains poorly quantified, particularly under anthropogenic stressors. Demersal trawling activity is the most significant cause of widespread anthropogenic disturbance to the seabed, leading to massive sediment resuspension events and wide scale impact to benthic communities. The impacts of trawling on benthic ecosystems and biodiversity are well reported and understood within the literature (e.g. Jones, 1992; Rijnsdorp et al., 2016); however, a knowledge gap remains regarding the post-trawl fate of sedimentary carbon (van de Velde et al., 2018).

In order to gain a better understanding of the post-disturbance effects of carbon cycling in marine sediments, an experimental trial to mimic fishing impacts was created. Over a 21-day period, a series of closed-tank incubation experiments investigating the impact of simulated benthic fishing gear penetration depth in soft sediments was conducted. Here, marine sediments underwent an artificial disturbance event every 24 hours, with a series of varying depth regimes used. We hypothesise that the large-scale resuspension events caused by trawling may contribute towards an enhancement in localised carbon cycling, and thus a reduction in the net carbon storage within these sediments. The aim of this experiment was to better understand the biogeochemical processes which occur in marine sediments during massive resuspension events, with a particular emphasis on the fate of resuspended organic carbon matter and its potential vulnerability. Dissolved organic carbon and various macronutrients of interest (e.g. PO4, SiO2, NH4, NO2, NO3) were also measured.

Jones, J.B., 1992. Environmental impact of trawling on the sea bed: a review. New Zeal. J. Mar. Freshw. Res. 26, 59–67. https://doi.org/10.1080/00288330.1992.9516500org/10.1080/00288330.1992.9516500

Rijnsdorp, A.D., Bastardie, F., Bolam, S.G., Buhl-Mortensen, L., Eigaard, O.R., Hamon, K.G., Hiddink, J.G., Hintzen, N.T., Ivanović, A., Kenny, A., Laffargue, P., Nielsen, J.R., O’Neill, F.G., Piet, G.J., Polet, H., Sala, A., Smith, C., Van Denderen, P.D., Van Kooten, T., Zengin, M., 2016. Towards a framework for the quantitative assessment of trawling impact on the seabed and benthic ecosystem. ICES J. Mar. Sci. 73, i127–i138. https://doi.org/10.1093/icesjms/fsv207

van de Velde, S., Van Lancker, V., Hidalgo-Martinez, S., Berelson, W.M., Meysman, F.J.R., 2018. Anthropogenic disturbance keeps the coastal seafloor biogeochemistry in a transient state. Sci. Rep. 8. https://doi.org/10.1038/s41598-018-23925-y
Forced and chaotic variability of interannual variability of regional sea level and its causes scale over 1993-2015
Authors: Carret Alice , Llovel William , Penduff Thierry , Molines Jean-Marc , Meyssignac Benoît
Published: March 2020

Since the early 1990s, satellite altimetry has become the main observing system for continuously measuring the sea level variations with a near global coverage. Satellite altimetry has revealed a global mean sea level rise of 3.3 mm/yr since 1993 with large regional sea level variability that differs from the mean estimate. These measurements highlight complex structures especially for the western boundary currents or the Antarctic Circumpolar Current. A recent study shows that the chaotic ocean variability may mask atmospherically-forced regional sea level trends over 38% of the global ocean area from 1993 to 2015. The chaotic variability is large for the western boundary currents and in the Southern Ocean. The present study aims to complement this previous work in focusing on the interannual variability of regional sea level. A global ¼° ocean/sea-ice 50-member ensemble simulation is considered to disentangle the imprints of the atmospheric forcing and the chaotic ocean variability on the interannual variability of regional sea level over 1993-2015. We investigate the forced (i.e., ensemble mean) versus the chaotic variability (i.e., ensemble standard deviation) for the interannual variability of regional sea level and its causes (i.e., steric sea level and manometric sea level contribution). We complement our investigations by partitioning the steric component into thermosteric sea level (i.e., temperature change only) and halosteric sea level (i.e., salinity change only). One of the goals of the study is to highlight the hot spots region of large chaotic variability for regional sea level and its different components.
Uncertainties associated with the delineation of management zones in precision agriculture
Authors: Tenreiro Tomás R. , García-Vila Margarita , Gómez José A. , Fereres Elías
Published: March 2020

The characterization of spatial variations in soil properties and crop performance within precision agriculture, and particularly the delineation of management zones (MZ) and sampling schemes, are complex assignments currently far from being resolved. Considerable advances have been achieved regarding the analysis of spatial data, but less attention has been devoted to assess the temporal asymmetry associated with variable crop×year interactions. In this case-study of a 9 ha field located in Spain, we captured interactions between both spatial and temporal variations for two contrasting seasons of remotely sensed crop data (NDVI) combined with several geomorphological properties (i.e., elevation, slope orientation, soil apparent electrical conductivity - ECa, %Clay, %Sand, pH). We developed an algorithm combining Principal Component Analysis (PCA) and clustering k-means and succeeded to delineate four MZ’s with a satisfactory fragmentation degree, each one associated with a different Elevation×ECa×NDVI combination. Simulated yield maps were generated using NDVI maps correlated to ground cover to establish initial conditions in simulation settings with a crop model. Yield maps were spatially correlated but fitted into variograms with irregular spatial structure. Both CV and spatial patterns did not show consistency from year to year. The results indicate that MZ’s temporal instability is an important issue for site-specific management as agronomic implications varied greatly with crop×year setting. We observed differences, not only regarding NDVI patterns but also in yield response to the combination of Elevation×ECa (and Texture) depending on the seasonal rainfall. A reduction of 14% of the ’Goodness of Variance Fit’ was observed for simulated yield from the first to the second crop×year, highlighting the difficulties in the delineation of MZ’s with persistent confidence. The interpretation of MZ×Yield associations was not straight forward from the metrics selected here as it also depended on agronomic knowledge. We believe that precision agriculture will benefit greatly from improved protocols for MZ delineation and sampling schemes. However, the uncertainty associated with temporal asymmetry of yield clustering and MZ’s interpretation reveals that ‘automated digital agricultural systems’ are still far from reality.
WaterApps: co-producing tailor-made water and weather information services with and for farmers for sustainable agriculture in peri-urban delta areas in Ghana and Bangladesh
Authors: Paparrizos Spyridon , Gbangou Talardia , Kumar Uthpal , Sarku Rebecca , Merks Joreen , Werners Saskia , Dewulf Art , Ludwig Fulco , van Slobbe Eric
Published: March 2020

Water for agriculture in peri-urban areas is vital to safeguard sustainable food production. Due to the dynamics of urbanization in deltas as well as climate change, water availability (too much, not enough, too late or early) is becoming erratic and farmers cannot rely only on their own experience anymore for agricultural decision-making. The WaterApps project develops tailor made water and weather information services with and for farmers in peri-urban areas in the urbanizing deltas of Accra, Ghana and Khulna, Bangladesh to improve water and food security and contribute towards sustainable agriculture.

The project’s design framework initially focuses on the farmers that are involved and supported during its course in the study areas and assesses their needs. Based on the baseline needs assessment study and along with the farmers in a co-producing mode Climate Information Services are being developed that provide tailor-made water and weather information and are continuously monitored and evaluated to ensure their effectiveness.

WaterApps combines the latest information technology such as Apps, social media, etc. on knowledge sharing that are enhanced with the local farmers’ information needs, demands and preferences to produce tailor-made Climate Information Services.

It deals with the technical part & design aspects of the water and climate information services, such as: the skill of the provided information on different spatio-temporal scales and the role of Local Forecasting Knowledge in the study areas.

Currently, an APP is being developed which, besides displaying scientific forecast gives the possibility to farmers to provide their own indigenous forecast. Additionally, scientific and indigenous forecast are being integrated providing a hybrid forecast.

In Bangladesh, Farmers’ Fields Schools (FFS) have been initiated together with meetings and trainings. The objective was to engage with farmers on a weekly basis by providing long term weather forecast and discuss the relevance in relation to upcoming agricultural activities. Social media are employed to inform agricultural extension officers and stakeholders on a daily basis.

Both cases in Bangladesh and Ghana show the importance of two-way communication and co-production with and for farmers. The co-production of water and weather information services empowers and improves livelihoods of small/medium farmers and builds capacity for enhancing sustainable food production. Finally, it lays the ground for upscaling in other urban-rural delta zones in the developing world.
What could we learn about climate sensitivity from variability in the surface temperature record?
Authors: Annan James , Hargreaves Julia , Mauritsen Thorsten , Stevens Bjorn
Published: March 2020

We examine what can be learnt about climate sensitivity from variability in the surface air temperature record over the instrumental period, from around 1880 to the present. While many previous studies have used the trend in the time series to constrain equilibrium climate sensitivity, it has recently been argued that temporal variability may also be a powerful constraint. We explore this question in the context of a simple widely used energy balance model of the climate system. We consider two recently-proposed summary measures of variability and also show how the full information content can be optimally used in this idealised scenario. We find that the constraint provided by variability is inherently skewed and its power is inversely related to the sensitivity itself, discriminating most strongly between low sensitivity values and weakening substantially for higher values. As a result of this, is only when the sensitivity is very low that the variability can provide a tight constraint. Our results support the analysis of variability as a potentially useful tool in helping to constrain equilibrium climate sensitivity, but suggest caution in the interpretation of precise results.
Sediment dynamics across gravel-sand transitions: Implications for river stability and floodplain recycling
Authors: Dingle Elizabeth , Sinclair Hugh , Venditti Jeremy , Attal Mikael , Kinnaird Tim , Creed Maggie , Quick Laura , Nittrouer Jeffrey , Gautam Dilip
Published: March 2020

The gravel-sand transition is observed along most rivers. It is characterized by an abrupt reduction in median bed grain size, from gravel- to sand-size sediment, and by a shift in sand transport mode from wash load-dominated to suspended bed material load. We document changes in channel stability, suspended sediment concentrations, flux and grain size across the gravel-sand transition of the Karnali River, Nepal. Upstream of the gravel-sand transition, gravel-bed channels are stable over hundred to thousand-year timescales. Downstream, floodplain sediment is reworked by lateral bank erosion, particularly during monsoon discharges. Suspended sediment concentration, grain size and flux reveal counterintuitive increases downstream of the gravel-sand transition. The results demonstrate a dramatic change in channel dynamics across the transition, from relatively fixed, steep gravel-bed rivers with infrequent avulsion to lower gradient, relatively mobile sand-bed channels. The increase in sediment concentrations and near-bed suspended grain size may be caused by enhanced channel mobility, which facilitates exchange between bed and bank materials.   These results bring new constraints on channel stability at mountain fronts, and indicate that temporally and spatially limited sediment flux measurements downstream of gravel-sand transitions are more indicative of flow stage and floodplain recycling than of continental-scale sediment flux and denudation rate estimates.
High tremolite asbestos content in urine related to dispersion from NOA rocks: a case study
Authors: Belluso Elena , Capella Silvana
Published: March 2020

The naturally occurring asbestos (NOA) and naturally occurring of asbestiform minerals non asbestos classified (NONA) in North Western Italian Alps is known since many years and described in a few papers (e.g., Belluso et al., 1995; ARPA Piemonte, 2008). Whereas the noxiousness due to professional exposure to asbestos is well known, there are few information dealing with natural environmental exposure as that occurring to general population living closeness to NOA (and NONA) in outcropped rocks.

The investigation of inorganic fibres content in urine may understand if people respired them in the latest period (from several days to some months: e.g., ATSDR, 2001).

In this study we present a case of a very high and abnormal content of tremolite asbestos detected in urine of a young girl during a survey of several toxic contaminants respired from young students in a Turin province school (NW Italy).

The absence of asbestos revealed by further investigation carried out in urine sample of girl’s parents and in other samples from the girl, showed that the high asbestos content previously detected was due to an exposure occurrence limited in time and related only to the girl.

The investigation carried out on the lifestyle of the girl in the year preceding the urine analysis allowed to suppose that the detected high content of tremolite asbestos might be due to a specific environmental exposure. Indeed, the girl spent a holiday period away from her habitual home, where there were excavation works in NOA rocks spotty containing important amount of tremolite asbestos. Therefore, the asbestos detected in the urine is probably connected to those dispersed from NOA rocks.

This finding focuses on the need to evaluate the risk of asbestos air dispersion from NOA rocks before carrying out excavation works.

 

ARPA PIEMONTE (2008) Amianto naturale in Piemonte. Agenzia Regionale per la Protezione Ambientale del Piemonte, ARPA Piemonte, Ed. L’Artistica Savigliano (CN), I

ATSDR, Agency for Toxic substances and Disease Registry (2001). U.S., Department of Health and Human Services, Public Health Service. Atlanta, GA, USA

BELLUSO E, COMPAGNONI R, FERRARIS G. (1995) Occurrence of asbestiform minerals in the serpentinites of the Piemonte Zone, Western Alps. In: Giornata di studio in ricordo del Prof. Stefano Zucchetti, Politecnico di Torino, 57-64. Ed. Politecnico di Torino, I