bluuebunny/crossref_metadata_2025 huggingface dataset:
Reuse of by-products coming from blasting of unstable rock elements.
Authors: Casale Marco , Dino Giovanna Antonella , Oggeri Claudio
Published: February 2023

The improvement of safety conditions of unstable rock slopes can be achieved through the use of explosives, for the removal of unstable rock elements. This technique is often applied because, most of time, drill and blast operations, where they can be used, are cheaper and faster than other techniques and require less subsequent maintenance interventions.When the activity is performed in an area that can be reached by vehicles (quarry area, slope above a road, etc…) it is possible to recover the blasted material.Depending on the size of the unstable element to be removed, this kind of operations often lead to the production of large quantities of blasted rocks, which most often ends up at landfill or is marginally reused in unqualified manner (construction of temporary tracks, filling voids left by extractive activity, etc…).Reusing blasted rocks can offer several benefits: more sustainable engineering practices, economic, environmental and social benefits; in particular, this way of operating can preserve natural resources and prevent the production of unwanted waste. As a rule, on-site and nearby-site reuse is preferred to meet sustainable goals. Specific cases where blasted material has been adopted for both slope protection and final rehabilitation works, in a quarry area, can be mentioned.Unfortunately, due to unclear legislation, lack of technical data and extreme variability of the materials produced (for instance quantity, size and physical properties), the use of blasted material is not common: It can be estimated that only 20-30% of these materials are currently reused properly.To improve this practice, the type of reuse must be a design goal since the beginning of the planning phase.According to the quality of the rock mass and the type of blasting, different by-products can be obtained, i.e. armour stones to be applied in hydraulic engineering works, gabion stones, drainage stones and crusher run as a mix of different types of aggregates, that can be employed as paver layer on road construction.When ornamental stone quarries are involved, hard rock fragments are obtained for high mechanical performances.The main purpose of blasting demolition of unstable rock elements, as mentioned, is to improve the safety conditions of the site, depending on local features, as well as by the safety of the workers, that can force the blasting scheme geometry and firing and impose important limitations on the operating techniques.Two case studies will be presented, both in the Verbano-Cusio-Ossola (VCO; Piemonte - NW Italy) extractive area; they show how the blast design can be arranged to obtain different fragmentation and greater quantities of a specific by-product, according to the local needs and specific reuse. Key words: by products, blasting, muck reuse, solid waste, slope protection.
Beyond ozone hole impacts: Seamless composition-climate interactions explored with ICON-ART
Authors: Braesicke Peter , Hanft Valentin , Kusakova Katerina , Ruhnke Roland , Satitkovitchai Khompat , Sinnhuber Björn-Martin , Versick Stefan , Weimer Michael
Published: February 2023

The ICOsahedral Non-hydrostatic (ICON) modelling system was originally developed by DWD and MPI-M for a range of weather (forecast) and climate applications. An Aerosols and Reactive Tracers (ART) module was added by KIT to enable a comprehensive assessment of composition interactions within the atmospheric domain. Recognising that atmospheric processes happen on a multitude of temporal and spatial scales, flexible horizontal and vertical grid options are a key element of versatile model configurations in use. Here, we present a selection of results from different ICON-ART configurations that explore (stratospheric) ozone-climate interactions and stratosphere-troposphere coupling – e.g. regional climatic impacts of the ozone hole (and ozone losses in other regions) and global warming induced changes in jet-streams – in different types of integrations. In addition, we explore the potential to forecast “chemical weather” with ICON-ART, including environmental (UV) indices.Starting with time-slice experiments, we provide a range of examples using the ICON-ART modelling system to investigate (idealised) climate change scenarios with respect to different threshold temperatures (reached under global warming) and the climatic impact of the ozone hole (and ozone losses in other regions). For the latter, halogen induced depletion of (stratospheric) ozone can be switched on and off in our modelling world. We illustrate how such integrations allow the unambiguous attribution of certain climate change effects, e.g. the contribution of the ozone hole (and other regional ozone losses) to regional surface warming in Antarctica and changes to regional and global “effective radiative forcing”, and the change of jet stream variability under global warming. Moving on, we explore the capability of ICON-ART to work with regionally nested grids to capture accurately smaller spatial scales and to provide “meaningful” forecasts of environmental (UV) indices, thus, demonstrating comprehensively the seamless philosophy regarding processes, scales and applications with the flexible ICON-ART modelling system.
In search of the triggers of increasing sediment loads to Lake Kivu
Authors: Lizaga Ivan , Bodé Samuel , Van Oost Kristof , Bagalwa Montfort , Katcho Karume , Ciraba Honoré , Blake William , Evrard Olivier , Latorre Borja , Navas Ana , Boeckx Pascal
Published: February 2023

Extensive agriculture and mining practices increase erosion and sediment transport leading to natural disasters, such as flash floods, landslides and water quality degradation. This is especially evident in areas with high and episodic rainfalls and lousy land use and agricultural management, such as the Lake Kivu region in the eastern Democratic Republic of the Congo (DRC). Due to the growing population and the need to increase crop productivity in the region, poor agriculture practices combined with unmonitored mining lead to severe soil degradation increasing erosion rates and sediment and nutrient export to the surrounding water bodies. In this regard, the Kivu Lake area has experienced an increase in sediment export rates of various orders of magnitude in the last ten years without an obvious triggering factor. This increase is noticeable by the vast growth in its river’s deltas built by sediment carried by the intense episodic rainfalls. For this reason, understanding the leading factor to the last decade’s increase in sediment export is crucial to prevent further degradation of the ecosystems.A combined approach of sediment sampling and remote sensing was used. Different methodologies were implemented to collect sediments in Lake Kivu close to the outflow of the rivers along the entire Congolese Rivershore of the lake, targeting areas with different landscape attributes. First, volcanic soils and the absence of natural vegetation characterise the northern part. The central part is an area with intensive mining activities, scarce agriculture and frequent landslides. Finally, in the South, we could discriminate two areas, one with high agriculture density but with a natural park at the headwaters, and the area of Bukavu, which combines all previous factors with a high input of pollutants from the city.The information extracted from the sediment samples, such as nutrients, grain size and pollutants, will be combined with a detailed remote sensing study integrating UAV, Planet and Sentinel imagery to target the possible factors leading to the last decade’s increase in sediment export. This study will enable researchers and policymakers to explore erosion extent, identify possible drivers and hotspots, and work with stakeholders to develop soil conservation strategies.
Machine learning applications for weather and climate need greater focus on extremes
Authors: Watson Peter
Published: February 2023

Multiple studies have now demonstrated that machine learning (ML) can give improved skill for simulating fairly typical weather events in climate simulations, for tasks such as downscaling to higher resolution and emulating and speeding up expensive model parameterisations. Many of these used ML methods with very high numbers of parameters, such as neural networks, which are the focus of the discussion here. Not much attention has been given to the performance of these methods for extreme event severities of relevance for many critical weather and climate prediction applications, with return periods of more than a few years. This leaves a lot of uncertainty about the usefulness of these methods, particularly for general purpose models that must perform reliably in extreme situations. ML models may be expected to struggle to predict extremes due to there usually being few samples of such events.  This presentation will review the small number of studies that have examined the skill of machine learning methods in extreme weather situations. It will be shown using recent results that machine learning methods that perform reasonably for typical weather events can have very large errors in extreme situations, highlighting the necessity of testing the performance for these cases. Extrapolation to extremes is found to work well in some studies, however.  It will be argued that more attention needs to be given to performance for extremes in work applying ML in climate science. Research gaps that seem particularly important are identified. These include investigating the behaviour of ML systems in events that are multiple standard deviations beyond observed records, which have occurred in the past, and evaluating performance of complex generative models in extreme events. Approaches to address these problems will be discussed.
A new calibration method for the stochastic rotating shallow water model
Authors: Lang Oana , Crisan Dan , Lobbe Alexander
Published: February 2023

In recent years, the applications of stochastic partial differential equations to geophysical fluid dynamics has increased massively, as there are several complex dynamic models which can be represented using systems of SPDEs. An important problem to be adressed in this context is the correct noise calibration such that the resulting stochastic model efficiently incorporates the a priori unrepresented sub-scale geophysical processes. In this talk I will present a new method of stochastic calibration which can be applied to a class of stochastic fluid dynamics models. I will focus on an application specifically tailored for the stochastic rotating shallow water model. 
Fully coupled heat transport modelling in porous media considering transfer between phases
Authors: Lee Haegyeong , Wilkins Andy , Blum Philipp , Bayer Peter , Rau Gabriel
Published: February 2023

Accurate prediction of heat transport in porous media is important for understanding geoscience processes and properties and to design applications, for example geothermal energy systems. While heat transport is generally modelled assuming of local thermal equilibrium (LTE), i.e., instantaneous heat transfer between the fluid and solid phases, previous studies have demonstrated presence of local thermal non-equilibrium (LTNE), i.e., delayed heat transfer, in natural porous materials. However, factors that influence the rate of heat transfer between the phases and their significance for inherently heterogeneous natural systems remain unknown and untested. We develop an open-source fully coupled, finite-element application to numerically simulate heat transfer between the fluid and solid phases. This is based on the Multiphysics Object-Oriented Simulation Environment (MOOSE) and allows massively parallel modelling of heat transport including customized transfer rates. We verify our model using an analytical solution considering LTNE and illustrate several applications. The model can be used to investigate processes that affect heat transport such as heat transfer mechanisms and their dependence on different hydrogeological conditions.
Influence of wind speed and wind direction above the sea surface on the diffusive methane flux and the atmospheric methane concentration at the North Sea
Authors: Bussmann Ingeborg , Achterberg Erich , Brix Holger , Brüggemann Nicolas , Fischer Philipp , Flöser Götz , Greinert Jens , Ködel Uta , Schütze Claudia
Published: February 2023

The estimations of the diffusive methane flux from the water phase into the atmosphere in coastal waters is relevant for a better estimate of the atmospheric greenhouse-gas budget. Unfortunately, so far, the numerical determination of the fluxes has a high level of uncertainty in coastal waters.To improve the estimation of coastal methane fluxes, not only a high temporal and spatial sampling resolution of the dissolved methane in the water are required. Besides, also the atmospheric methane concentration and the wind speed and wind direction above the surface is important. In most cases, these atmospheric data are obtained from near-by atmospheric and meteorologic monitoring stations. In this study, we measured wind speed, direction and atmospheric methane local directly on board of three research vessel cruising in the southern North Sea within the MOSES project and compared the effects of local versus remote measurements of these data on the flux data. In addition, using the wind direction and speed, we try to assess the origin of the atmospheric methane measured in the study area. Using these “improved” data sets, we discuss if local measurements of auxiliary data provide better insights in the determining factors of the methane flux, and thus also improve the regional aquatic methane budget.
Revisiting the hockey stick curve: exploring an alternative metric for incorporating the role of stratification in distinguishing turbulence regimes in the stable boundary layer
Authors: Thomas Christoph , Huss Jannis-Michael
Published: February 2023

Identifying turbulence regimes in the stable boundary layer (SBL) is not only important for advancing our fundamental understanding of turbulent mixing but is also needed for model-observation intercomparisons and to build meaningful Earth system science models for predicting future climate change in regions subject to weak winds and significant radiative cooling. As a common regime classification, the classic hockey stick curve (Sun et al., 2012) relates the turbulence kinetic energy to the mean horizontal wind speed and differentiates between (1) weak turbulence driven by local shear and (2) strong turbulence driven by the bulk shear separated by a height-dependent threshold. A third (3) intermittent regime marks transitions between the former. However, the effect of thermal stratification on the surface heat fluxes is not directly included in this metric. Here, we explore the recently proposed decoupling metric Ω = LB (z√2)-1  (Peltola et al., 2021) to overcome this limitation as the buoyancy length scale LB ∝ NBV-1 directly incorporates the stratification through the bulk Brunt-Vaisala frequency. Analyzing multi-level observations in persistent polar SBLs, short-lived SBLs over snow and topographically sheltered nocturnal SBLs we found that Ω versus wind speed exhibits an even more clearly pronounced hockey stick behavior with a sudden regime change from (1) to (2), but without the intermittent (3). In contrast to the classic hockey stick metrics, heat fluxes were largest for an intermediate Ω within the strong regime (2) but above the critical threshold velocity. In the SBL, heat fluxes vanished for either very small stratification and, hence, weak gradients, leading to large Ω > 1 in (2), or in (1) as vertical transport is suppressed by the strong stratification. The observations satisfied a simple linear model to predict the threshold Ωcrit from height-dependent wind speed. The latter resembled a classic neutral boundary layer profile with meaningful friction velocities and surface roughness length, suggesting that turbulent transport is coupled to the local surface throughout regime (2). The height-dependence of Ωcrit,however, suggests that z is not the most appropriate vertical length scale in the SBL even for the strong turbulence regime.References:Peltola, O., Lapo, K., & Thomas, C. K. (2021). A Physics-Based Universal Indicator for Vertical Decoupling and Mixing Across Canopies Architectures and Dynamic Stabilities. Geophysical Research Letters, 48(5), e2020GL091615. https://doi.org/https://doi.org/10.1029/2020GL091615;Sun, J., Mahrt, L., Banta, R. M., & Pichugina, Y. L. (2012). Turbulence Regimes and Turbulence Intermittency in the Stable Boundary Layer during CASES-99. Journal of the Atmospheric Sciences, 69(1), 338–351. https://doi.org/10.1175/JAS-D-11-082.
Oil saturation quantitative evaluation in lacustrine shale: A novel insight from NMR T1-T2 experiments
Authors: Zhang Shaolong , Cai Jingong , Yan Jianping , Zhu Xiaojun , Wang Min
Published: February 2023

Oil saturation is important for shale reservior to identify favorable sections and mapping the geological sweet spot. Current oil saturation evaluation methods, including experiments and empirical formulas, are not suitable for shale reservoir because of the complex mineral, fluid components and pore structure characteristics. To establish the shale oil saturation calculation model, X-ray diffraction, one-dimension and two-dimension nuclear magnetic resonance (NMR), and oil-water two-phase displacement experiments were employed on shale samples collected in the upper sub-member of the fourth member of the Eocene Shahejie Formation in the Dongying sag, Jiyang Depression, Bohai Bay Basin. After data analysis, the reason for whether oil is produced in the displacement experiments were explained, distribution characteristics of different shale components in the NMR T1-T2 map were analyzed, and a new shale oil saturation calculation method was proposed using NMR T2 sensitive parameters that reflected the changes of NMR T2 spectrum morphological characteristics with different oil saturation calibrated by NMR T1-T2 map at different displacement stage. The results indicated that the pore structure of shale samples is complex and show strong heterogeneity according to the NMR T2 spectrum, and the distribution of shale pore size is the main factor determining whether there is oil in the volumetric cylinder in the displacement experiment under the premise of the slight difference of wettability. NMR T1-T2 map is an effective way to identify different components (kerogen and solid bitumen, adsorbed oil, free oil, structural and adsorbed water, free water) of shale samples, and usually, kerogen and solid bitumen distributed in the top left of the T1-T2 map with T1>10 ms, T2<0.1 ms. Based on this, T2 threshold for free oil and adsorbed oil are 2 and 0.2 ms, and the corresponding threshold of pore radius are 40 and 4 nm according to the NMR theory. As NMR T2 spectrum sensitive parameters, geometric mean and interval porosity corresponding to the first peak are positively and negatively correlated with oil saturation respectively. With understanding this, oil saturation calculation method is established using the above two parameters and the Root Mean Square Error (RESM) between the measure oil saturation and the calculated results is 5.78%, which reflecting the accuracy and validity of the method. In general, this method allows the shale oil saturation to be accurately calculated and provides a parameter basis for the determination of favorable sections and evaluation of resource of shale oil reservoir. Moreover, it also offers a new idea for the oil saturation predication by NMR logging.
Characterization of macropore-matrix mass transfer parameters in two-domain preferential flow models
Authors: Gerke Horst H.
Published: February 2023

The macropore-matrix mass transfer of water and solutes is an important aspect of non-equilibrium-type of preferential flow in structured soils. For a representative soil volume, effective mass transfer parameters depend on heterogeneous local properties of the soil macropore structure, its geometry and shape, and on properties at macropore walls that can differ from those of the matrix with respect to texture, organic matter, bulk density, and porosity. These affect the soil pore system locally with respect to hydraulic, mechanic, bio-geo-chemical, and other processes. Clayey aggregate skins, for example, may be more due to plastic deformation but can restrict water exchange; solutes may become adsorbed along macropore surfaces and released under changing condition. Still relatively little is known about formation of such local biological hotspots in soil, on how to determine the local mass transfer parameters, and how to upscale to the scale of the soil volume, and on the interrelations between all the individual local properties and the combined effect on relevant bulk soil transport processes. The present contribution reviews recent experimental and modeling work including field and lab percolation experiments using the movement of bromide, Brilliant Blue, iodide, and Na-Fluorescein to identify the flow paths and parameter optimization approaches for determining such parameters. It seems that preferential transport of reactive solutes depends even more strongly on the geometry and properties at flow paths surface than the water flow itself or the movement of conservative solutes. The identification and determination of effective mass transfer parameters in two-domain models remains a challenge when considering that local changes in the soil structure are highly dynamic during the vegetation, the seasons, and due to soil management.
NO2 absorption correction for enhanced AOD retrieval
Authors: Raptis Ioannis Panagiotis , Drosoglou Theano , Valeri Massimo , Casadio Stefano , Barnaba Francesca , Brizzi Gabriele , Niro Fabrizio , Campanelli Monica , Kazadzs Stelios
Published: February 2023

Aerosol Optical Depth (AOD) retrieval from sunphotometric measurements is sensitive to the concentration of atmospheric gases (e.g. NO2), particularly in UV and lower visible spectral range. Current algorithms used in aerosol networks  either use  climatological NO2 to estimate the corresponding absorption or it is totally ignored . NO2 in the atmosphere is characterized by high spatial and temporal variations, especially in urban areas. Thus, climatological values are rarely representative of the actual NO2 concentration, introducing non-negligible errors in AOD retrievals at specific spectral regions.We propose a correction approach, using synchronous data from different networks/instruments. AOD is retrieved by sunphotometers (CIMEL and PREDE-POM) in AERONET and SKYNET networks. NO2 total column is calculated by direct sun measurements of PANDORA spectroradiometers, part of PANDONIA network. Data from three stations, with colocation of these instruments are used in presented study to apply the correction and evaluate the new datasets. Two stations in Rome, Italy (Sapienza University at City Center and CNR-ISAC at Tor Vergata in suburban area) and one in Athens, Greece (National Observatory of Athens at city center). More specifically the NO2 correction is applied on AOD at four bandwidths (340, 380, 400 and 440 nm). Propagation of the correction to the calculated Ångström Exponent is also estimated.Highest mean relative differences are found at 440nm which are up to 1.7% for AERONET data and 5.3% at 400 nm for SKYNET (which’s algorithm does not consider NO2). Highest absolute AOD difference found was 0.037 at 440nm. For Ångström Exponent 440-870 absolute maximum difference found was 0.31.Finally, cases of days with high NO2 variability and the corresponding effect on AOD calculations will be presented.
Monitoring of soil moisture response as part of the ecohydrological cycle
Authors: Zabret Katarina , Lebar Klaudija , Alivio Mark Bryan , Bezak Nejc , Šraj Mojca
Published: February 2023

Ecohydrological cycle in addition to common hydrological components such as rainfall, runoff and evaporation, strongly focuses also on ecological elements, i.e. elements of the nature and their role in the water cycle. As such we have addressed the role of two natural elements in the water balance of the study plot: vegetation (trees) through rainfall interception process and the soil through water infiltration and soil moisture dynamics. The study plot covers small urban park in the city of Ljubljana, Slovenia and includes the opening with low-cut grass, group of birch trees and group of pine trees. There we are monitoring rainfall and its characteristics, as well as throughfall and stemflow under each group of trees since the year 2014. Additionally, in 2021 we have started to measure also soil moisture (volumetric water content; VWC) at three depths (16 cm, 51 cm and 74 cm) and at three locations: in the open, under the birch and under the pine trees. During the measurements of soil moisture, we have captured the distinctly dry period of spring and summer of 2022, as well as excess of rainfall amount according to the long-term average during September 2022. For the collected data set we have used statistical approaches to analyse influence of vegetation (rainfall interception) on values and response of soil moisture as well as influence of pre-event conditions on the response and dynamics of soil moisture.Acknowledgments: Results are part of the CELSA project entitled “Interception experimentation and modelling for enhanced impact analysis of nature-based solution” and research programmes and projects P2-0180, J6-4629, and N2-0313 financed by the Slovenian Research Agency (ARRS).
Positive chemotaxis of plant growth-promoting rhizobacteria to the ionized form of rutin
Authors: Likhanov Artur
Published: February 2023

Flavonoids are known to perform complex physiological functions in the plant organism. The synthesis of flavonoids, their quantitative and qualitative composition depends on the genotype, age and habitat of the plant. Flavonoids are predominantly synthesized in assimilating organs and then distributed throughout the plant organism. Part of the flavonoids is released through the roots into the rhizosphere. Depending on the chemical structure, flavonoids in the soil can be ionized, oxidized or form covalent adducts with thiol compounds, complexes with metals or ammonium forms of nitrogen.Rutin (quercetin-3-O-rutinoside), when excreted by plant roots in a slightly alkaline environment, like most flavonols, is partially ionized, acquiring greater mobility in soil solutions. In combination with ammonium nitrogen, rutin actively spreads in the rhizosphere and is recognized by rhizospheric bacteria. Thus, PGPR (plant growth-promoting rhizobacteria) isolated from the seed coat of soybean (Glycine max (L.) Merr.) reveal high sensitivity to rutin-ammonium complexes. Pseudomonas putida strain PPEP2-SEGM-0220 (GenBank: MW255059.1) stimulated the growth of main and lateral roots in soybean seedlings. The sensitivity of this strain to the rutin-ammonium complex on nutrient medium (King's B) was found at a solution concentration of 5 µg/ml. This indicates that the ionized form of rutin is biologically active and performs the function of a selective attractant for symbiotic microorganisms in the rhizosphere. Obviously, isolated PGPRs have molecular mechanisms for recognition of the rutin-ammonium complex. The presence of positive chemotaxis increases the probability of colonization of the plant with the PGPR strains it needs. Thus, the processes of transformation of quercetin-3-O-rutinoside in the soil are extremely important in the formation of plant-microbial systems.
Assessment of climate change impacts and anthropogenic activities on the eastern part of the Nile Delta of Egypt
Authors: Abd-Elhamid Hany , Zeleňáková Martina , Kabeel Abd Elnaby , Mahdy Mohamed , Barańczuk Jacek , Barańczuk Katarzyna
Published: February 2023

Abstract Climate change and anthropogenic activities could have extensive impacts of coastal areas especially Deltas and lowlands that may be extremely affected by sea level rise and different human activities. According to the IPCC reports, the mean sea levels have been raised between 10 to 20 cm over the last century and expected to rise between 20 to 88 cm at the end of the current century. If no actions are taken, this rise could have extensive effects on coastal areas such as shoreline erosion, submergence of coastal cities and increasing the seawater intrusion into coastal aquifers. Also, anthropogenic activities including changes in the land use could increase such effects. This study aims to highlight the effect of climate change and anthropogenic activities on the Nile Delta of Egypt. The study focusses on the eastern part of the Nile Delta (Port Said governorate) where many changes in the land use have been observed in the last decades. The effect of climate change and anthropogenic activities on the Nile Delta are detected using GIS, RS data and numerical models. The Digital Shoreline Analysis System (DSAS) with ArcGIS are used in monitoring the shoreline change (SLC) based on satellite images for 50 years from 1974 to 2023. GIS is used to monitor shoreline changes and forecast future changes for the next 10 and 20 years. The results indicated that the shoreline had shifted inland with varying values along the coasts between 1974 and 2023, and the predictions indicated that it would continue to shift in 2034 and 2044. The rate of shoreline loss was 14 m/year from 1974 to 2000 and 16 m/year from 2001 to 2023 and predicted to be 12 m/year from 2023 to 2044. RS and GIS are used for investigating the land use changes (LUC) over the last 50 years for the period from 1974 to 2023 based on satellite images that were geometrically corrected by Supervised Classification to identify LUC in the Nile Delta. The results for the study period from 1974 to 2023 (50 years) reveal that urbanization has increased 18%, vegetation cover has increased 22%, water bodies and fish farms increased 40% and the bare land decreased 60% due to the development of the area in the studied period. The Eastern part of the Nile Delta is enormously affected by climate change and anthropogenic activities which require application of protection measures. Significant changes in shoreline and land cover for the study area were observed in the period from 1974 to 2023. Policy makers may use the results of this study to develop adaptation plans to safeguard the Nile Delta from anthropogenic activities and climate change.Keywords: Climate change, anthropogenic activities, shoreline change (SLC), land use change (LUC), RS and GIS, Nile Delta of Egypt.
Computation of the AMOC collapse probability using a rare-event algorithm
Authors: Jacques-Dumas Valérian , van Westen René M. , Dijkstra Henk A.
Published: February 2023

The Atlantic Meridional Overturning Circulation (AMOC) transports warm, saline water towards the northern North Atlantic, contributing substantially to the meridional heat transport in the climate system. Measurements of the Atlantic freshwater divergence show that the AMOC may be in a bistable state and hence subject to collapsing under anthropogenic greenhouse gas forcing. We aim at computing the probability of such a transition, focusing on time scales up to the end of this century.  Simulating trajectories in a climate model is very expensive. To minimize the amount of data required to compute the probability of such rare AMOC transitions, we use a rare-events algorithm called TAMS (Trajectory-Adaptive Multilevel Sampling), that encourages the transition without changing the statistics. In TAMS, N trajectories are simulated and evaluated with a score function; the poorest-performing trajectories are discarded, and the best ones are re-simulated.The optimal score function is the committor function, defined as the probability that a trajectory reaches a zone A of the phase space before another zone B. To avoid the difficulties raised by its exact computation, we estimate it using a feedforward neural network. Because of the expense of simulating data in a climate model, we also minimize the amount of data needed to train the neural network by reusing data processed through TAMS.As a first step, using simulated data from an idealized stochastic AMOC model, where forcing and white noise are applied via a surface freshwater flux, we compute the transition probabilities versus noise and forcing amplitudes. Then, we apply the same protocol to compute these transition probabilities in the much more sophisticated climate model FAMOUS. This model is a coarse resolution Atmosphere-Ocean General Circulation Model that has been shown to exhibit a collapse of the AMOC via hosing experiments. In this new setup, we compute once again the transition probabilities of the AMOC versus noise and forcing, where the forcing amplitude is a hosing flux, and the atmosphere dynamics plays the role of the noise.
Is global burned area declining due to cropland expansion? How much do we know based on remotely sensed data?
Authors: Zubkova Maria , Humber Michael , Giglio Louis
Published: February 2023

Globally, the amount of fire activity detected by satellite observations seems to have changed substantially in the last two decades. Discussions regarding the main force behind the current trends have dominated research in recent years, with several studies attributing the global decline in wildfires to the expansion of agricultural areas. Nevertheless, most studies have failed to acknowledge that the regions where these changing patterns have been observed are known to be data-poor.Here we discuss the uncertainties and limitations of remotely sensed data used to determine global trends in burned area and changes in their potential drivers. Specifically, we i) quantify changes in the amount of burned area and cropland area and illustrate discrepancies between commonly used datasets, ii) state the limitations of remote-sensed fire and land cover products, and iii) highlight recent fire-trend studies and hypothesize likely effects of the choice of datasets on their conclusions. We argue that to legitimately conclude that the reported global decline in fire activity is driven by cropland expansion, three conditions must be met. First, negative trends should be global in scope, not localized to a specific continent or region. Second, the trends in both fire activity and agricultural areas must be supported by data that definitively demonstrate such trends over time. And third, the decline in the amount of burned area must be documented within or proximal to the areas of cropland expansion.We demonstrate that a drastic decline in fire activity in the last 20 years was only observed within regions highly sensitive to coarse resolution fire product biases, while most regions/continents did not experience significant changes in the amount of burned area. Additionally, the analysis of several global land cover products reveals the lack of consistency in the direction and magnitude of the trend in cropland land cover type. And finally, based on the available data, no clear spatial relationship can be detected between areas experiencing cropland expansion and areas where the amount of burned area is declining.Therefore, our knowledge of anthropogenic effects on fire, while growing, remains incomplete, particularly the effects of cropland expansion on wildfires, due to the low confidence in estimated fire trends within human-managed land and lack of understanding of the spatial distribution of cropland expansion/loss.
Dayside auroral emission induced by proton deposition observed by EMM EMUS
Authors: Evans J. Scott , Chaffin Michael , Deighan Justin , Jain Sonal , Correira John , Soto Emmaris , Al Matroushi Hessa , Al Mazmi Hoor , England Scott , Fillingim Matthew , Holsclaw Greg , Lillis Rob , Lootah Fatma ,   MAVEN Team Members
Published: February 2023

The Emirates Mars Ultraviolet Spectrometer (EMUS) onboard the Emirates Mars Mission (EMM) observes the Martian dayglow at ultraviolet wavelengths (100-170 nm). EMUS disk observations show unexpected variations in atomic hydrogen, atomic oxygen, and carbon monoxide disk emissions. These variations display local time and hemispheric asymmetry and are observed in approximately 25% of the disk images. England et al. (2022; doi:10.1029/2022GL099611) suggested that the spatial structure, occurrence, and spectral characteristics of these variations are associated with changes in composition and photoelectron flux. Using a similar EMUS data set, Chaffin et al. (2022; doi:10.1029/2022GL099881) reported the first observations of neutral atmosphere auroral emission on the Martian dayside, which is not a new type of aurora but another observable form of proton aurora, and suggested that solar wind deposition is responsible for exciting the auroral emission. We further investigate these two potential drivers of the unexpected variations in EMUS disk observations using data from the Imaging Ultraviolet Spectrograph (IUVS), the Solar Wind Ion Analyzer (SWIA), the SupraThermal And Thermal Ion Composition (STATIC) instrument, and a magnetometer (MAG), all onboard NASA’s Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. We use vertical profiles of densities and temperatures retrieved from limb scan observations by IUVS to identify signatures of dynamics that correlate with unexpected variations in EMUS disk observations. We use measurements from all of the instruments to categorize and characterize EMUS observations in order to determine how changes in composition and solar wind deposition produce unexpected variations in the Martian ultraviolet dayglow.
Crustal-scale Vp velocity model building for a sparse regional OBS survey using full-waveform inversion: a case study from Japan Trench
Authors: Arntsen Børge , Khakhorov Umedzon , Weibull Wiktor
Published: February 2023

Ocean Bottom Seismometers (OBS), in conjunction with an active source, have for a longtime been used to investigate the crust and upper mantle. Conventionally a number of Seismometers are deployed along a line with relatively large separation (several kilometers) between each instrument. A large air-gun array is then used to create a number of recordings with distance between the receiver and source varying from zero up to several hundred kilometers.The data is usually analyzed with tomographic methods leading to a P-wave velocity model. Tomographic methods tend to produce velocity models with low resolution and lack of details. To increase resolution the Full Waveform Inversion (FWI) can be used. Velocity models estimated using FWI shows better resolution and are better constrained than tomographic models.Our work sets out to develop a FWI workflow for a sparsely sampled OBS data. We demonstrate high resolution crustal-scale velocity model building workflow based FWI for a deep water and sparse (6km) sampled 300 km long wide-angle OBS data. We use an initial model traveltime tomography inversion. We apply waveform inversion to constrain crustal and upper mantle layers more confidently and with increased resolution compared to conventional traveltime tomography with layer-based parameterization. FWI allows to reduce significantly data-fit error (i.e. rms error) and explains better larger offsets of an observed data compared to traveltime tomography.The workflow is developed and applied to data acquired in 2009 in the Japan Trench where the 130-150 Myrs old oceanic plate is subducting under Eurasia. Subduction zones plays an important role in Earth tectonics . Traveltme tomography inversion was used the 2009 Japan Trench dataset to construct velocity models and showed that P-wave velocities close to the trench axis, where the plate bends downward, are systematically lower than the P-wave velocities at larger seaward distances. This is interpreted as water penetration into the plate from the seafloor, causing serpentinization which decreases P-wave velocities. However, tomographic models does not reveal details of the velocity model, only smoothed averages. We hope that a velocity model generated by FWI has sufficiently increased resolution to reveal more details of the water penetration and geological setting along the Japan Trench. 
Oil and gas industry emissions in Saskatchewan, Canada: a case study in uncertain reduction trends
Authors: Seymour Scott , Xie Donglai , MacKay Katlyn , Li Hugh
Published: February 2023

The province of Saskatchewan, Canada, came under new oil and gas industry emission regulations in 2020 to meet Canada’s methane emission reduction target for 2025. Although the province reportedly met its reduction target only two years into a five-year commitment, this finding was based on a bottom-up inventory whose operator-reported data had not been public until very recently. With these data made public for the first time, we recreated the federal government inventory for Saskatchewan (2012-2022) to better understand where and how emissions have changed in response to new regulations. Not only will this shed light on the regulations themselves (an updated version of which will be under review for Canada’s longer-term targets), but this inventory will also permit more detailed comparisons with forthcoming top-down measurements.Since new measurements are expected to be included in this inventory structure, we also used recently published aerial LiDAR measurements to update the inventory. Importantly, while the unmodified inventory confirms the significant emission reduction reported by the Saskatchewan Government (~45% reduction), the inclusion of aerial measurement data suggests that emissions may have actually increased over the same time period. We discuss how the manner in which new measurements are included can influence the emission reductions relative to an uncertain baseline year, and we discuss whether a trend can be calculated reliably. Careful consideration will therefore be needed when including new measurement data into existing inventories. 
Study of ENMAP imagery for the application of methods for Phytoplankton Functional Types determination in coastal waters
Authors: Ruescas Ana B. , Garcia-Jimenez Jorge , Mueller Dagmar , Brockmann Carsten , Amoros Julia , Stelzer Kerstin
Published: February 2023

Monitoring and mapping of major phytoplankton groups (PG) or functional types (PFT) has been targeted as a relevant topic for the understanding and study of marine ecosystem, especially under the present climate change scenario. Developing of algorithms that determine the structure of the phytoplankton communities is a reality since the last 20 years, but not much advanced has been done in the field of image spectroscopy due to the lack of spaceborne sensors with a systematic high temporal and spatial scales. Some operational sensors are changing the game right now, like PRISMA, ENMAP and, in the future, SGB, CHIME and other developments in the hyperspectral dimension. Most of the approaches for determining PFT or PG are based on phytoplankton abundance, cell size or bio-optical properties that use chlorophyll-a or spectral features (absorption, backscatter, and/or reflectance) on water in the VIS-NIR range as inputs. These and other approaches based on machine learning and deep learning are being tested on ENMAP imagery over the Baltic Sea. We will use reflectance data provided by DLR. Comparison of atmospheric correction approaches seems to be a necessary step, and radiance data will be process with current available algorithms. Since ENMAP has 240 bands, and high spatial resolution (30 m), we will tackle the dimensionality reduction problem adapting well-known machine learning approaches to the sensor characteristics (https://isp.uv.es/soft_feature.html).
Integrated system development of a MEMS Pendulum Gravimeter
Authors: Utting Phoebe , Prasad Abhinav , Middlemiss Richard , Hammond Giles
Published: February 2023

Gravimetry has many valuable applications from volcanology to water resource management; being a method able to infer density variations beneath the ground. Therefore, it can be used to provide insight into subsurface processes such as those related to the hydrothermal and magmatic systems of volcanoes. Existing gravimeters are costly and heavy, but this is changing with the utilisation of a technology most notably used in mobile phone accelerometers: MEMS – (Microelectromechanical-systems). A team at the University of Glasgow has already developed a MEMS relative gravimeter. A second generation of the MEMS sensor is now being designed and fabricated in the form of a semi-absolute pendulum gravimeter. Pendulum gravimetry was one of the prominent methods for gravimetric measurements up until the 20th century. However, scientists and engineers reached the limit of fabrication tolerances and readout accuracy approximately 100 years ago. With micro/nanofabrication and modern electronics techniques, it is now feasible to create a competitive pendulum gravimeter again. The research presented here will focus on the testing of an integrated semi-absolute gravimeter system. This encompasses a MEMS pendulum device that’s encapsulated within a thermal enclosure and stationed on a horizontal isolation platform. Micro/nanofabrication processes have been used to create the pendulum device. An optical shadow-sensor has been developed to monitor its oscillation. This optical readout can provide measurements to sub-nanometre precision. Data collected from laboratory testing will be presented to demonstrating the progression being made towards a prototype field device. This data will include measurements of the influence of tilt-sensitivity and the seismic and shadow sensor noise floors. Altitude tests of the free-air effect will also be presented to demonstrate the current sensitivity of the device. If semi-absolute values of gravity can be measured, then instrumental drift concerns are reduced. With the high cost of current absolute devices then this device could provide the technological advancement required to realise large scale array gravimetry.

 

 

 
The Puy de Dôme Ice Nucleation Intercomparison Campaign
Authors: Lacher Larissa , Freney Evelyn ,   PICNIC team
Published: February 2023

The formation and impact of ice crystals in clouds remain a challenge to understand and thus to be predicted in models. In recent years, measurements of ice-nucleating particles (INPs) in ambient air have become more frequent, using well-established and novel techniques such as mobile cloud chambers and filter-based freezing assays. To assure that these techniques are working as intended, validation and intercomparison measurements are required. This is especially relevant due to ongoing efforts for the establishment of INP monitoring networks at the European level (ACTRIS; Aerosol, Clouds and Trace Gases Research Infrastructure) and in the United States (ARM; Atmospheric Radiation Measurement).Here we present results from PICNIC (The Puy de Dôme ICe Nucleation Intercomparison Campaign), conducted at a mountain site in Central France (1465 m a.s.l.) in October 2018. INP concentrations relevant in the mixed-phase cloud regime were determined using three online INP techniques (Colorado State University-Continuous Flow Diffusion Chamber, CSU-CFDC; Spectrometer for Ice Nuclei, SPIN; Portable Ice Nucleation Experiments, PINE) and seven filter-based offline freezing devices (FRankfurt Ice Nuclei Deposition FreezinG Experiment, FRIDGE; Ice Nucleation Droplet Array INDA; Ice Nucleation Spectrometer of the Karlsruhe Institute of Technology, INSEKT; CSU Ice Spectrometer, IS; Leipzig Ice Nucleation Array, LINA; LED based Ice Nucleation Detection Apparatus LINDA; Micro-Orifice Uniform Deposit Impactor–Droplet Freezing Technique, MOUDI-DFT). The campaign focused on INP concentration measurements performed at the same time and at comparable nucleation temperatures, which is why filter sampling for offline techniques was started and stopped simultaneously, and online INP measurements were conducted at similar thermodynamic conditions. While the ice chambers yielded reasonable agreements within factors of 2 to 5, with lower concentrations found by SPIN, a systematic deviation between filter samples collected directly outside on the station’s rooftop and those sampled downstream from a whole air inlet is observed. A potential loss of larger aerosol particles via the inlet and an impact of the disaggregation of larger aerosol particles in solution might cause these differences, which needs to be investigated in future studies.