bluuebunny/crossref_metadata_2025 huggingface dataset:
Can salt basins be modelled by magnetic data? A successful case study in the Eastern Mediterranean 
Authors: Bianco Luigi , Abbas Mahmoud , Speranza Luca , Garcea Bruno , Fedi Maurizio
Published: March 2024

We discuss the analysis of magnetic data in salt basins and their potential role as a key tool in these scenarios. The study was performed on the magnetic data of a deep-water area in the offshore Egypt, Eastern Mediterranean. The reduced to pole (RTP) magnetic anomalies was computed and filtered with the discrete wavelet transform (DWT) for the regional-residual separation. The filtered anomalies were interpreted as due to the contrast between the sedimentary layers and the diamagnetic salt dome. The multiscale boundary analysis allowed the extraction of lineaments representative of the salt bodies. Moreover, the inversion of the data using a 3D non-linear non-iterative technique produced a map of the salt in the area, which was derived without constraints from seismic or other external information. from the magnetic data interpretation was performed. It needed only a local estimation of the depth to the salt in few points, as provided by Euler deconvolution of magnetic data. This result well agrees with the top of the salt interpreted from the seismic data. Our findings are not obvious and demonstrate the potential of magnetic surveys as a self-consistent and low-cost tool in the exploration of salt basins, especially when the higher resolution seismic interpretation  could suffer of possible pitfalls or seismic data are inaccessible.
Using high penetration airborne LiDAR scanning to characterise the micro-environment of dense tropical forest.
Authors: Badouard Vincyane , Verley Philippe , Vincent Grégoire
Published: March 2024

Environmental heterogeneity occurring at small-spatial scale strongly influences the structure, composition, and functioning of tropical rainforests. Environmental filters particularly influence the establishment and survival of young individuals. The relative importance of different micro-environmental variables in shaping tree species distributions through their habitat preference and their regeneration niche however remains poorly known, due in particular to methodological limitations in the characterisation of the small-scale abiotic environment. In this study, we propose to address this knowledge gap and methodological limitation by using the latest LiDAR technology. LiDAR has already proven its ability to describe the 3D forest structure and topography on a fine scale. Forest structure and topography already allowed the prediction of important micro-climatic components for trees and notably light and associated air temperature and moisture as well as local drainage regime. LiDAR technology may also contribute to the prediction of other conditions essential to plant life: soil temperature, water and nutrient access. The LiDAR acquisition methods currently used to map forest structure have some limitations. Standard airborne laser scanning fails to describe the lower canopy in sufficient detail due to occlusion by the upper canopy. Here we explore the potential of low altitude high power laser with enhanced penetration to describe the structure of the forest understorey. We use the recorded laser pulse extinction to build a 3D model of light transmission through the canopy. We evaluate the capacity of the light transmission model to predict microclimatic variables which were monitored in the understorey for 10mo. We also derive a fine resolution digital terrain model from the airborne laser data and explore how soil characteristics covary with topographic features extracted from the DTM.
Particle-Associated Contaminant Transport in Rivers during High Discharge Events
Authors: Renner Dominik , Rügner Hermann , Ebner Martin , Fabregat-Palau Joel , Grathwohl Peter
Published: March 2024

The pressure on natural water resources and aquatic ecosystems will increase in the future, particularly in urban areas, as a result of climate change and population and economic growth. Rapid rates of urbanization may lead to an increase in impervious surfaces, resulting in higher runoff volumes and pollutant loads. While wastewater treatment technology made significant progress over time, it is reported that a significant part of runoff is still discharged directly into rivers. Besides dissolved compounds, many toxic compounds are associated with natural and anthropogenic particles and some small particles themselves have to be considered pollutants such as microplastics (MP) and tire wear particles (TWP).In the scope of this study, suspended river sediments are examined towards type and amount of transported anthropogenic particles as well as for the contaminant loading with organic pollutants such as per- and polyfluoroalkyl substances (PFAS) and polycyclic aromatic hydrocarbons (PAH). The overall aim of the study is to identify correlations between the different classes of contaminants (i.e., MP, TWP, PFAS, PAH) and physio-chemical parameters (e.g., total suspended solids (TSS), turbidity, total organic carbon (TOC)) or catchment-specific properties such as land use and geology, as well as event- and/or seasonal related features (e.g., rain intensity, 1st flush effects).The samples are collected during high discharge events in rivers with contrasting catchments regarding land use and geology in southwest Germany. PFAS analysis includes the monitoring of 40 different PFAS and the direct total oxidizable precursor (dTOP) assay to investigate the levels of precursor compounds that are not included in the target analysis. Preliminary results suggest a predominant transport of long-chain PFAS precursors on suspended sediments in rivers compared to targeted PFAS. Microscopic analyses of the collected particles after standard filtration, chemical treatment, and separation steps imply amounts of MP and TWP in the range of 0.1‰ of the total suspended sediment mass.
Towards a better understanding of the hybrid modelling methodology for streamflow prediction
Authors: Degenne Antoine , Bourgin François , Perrin Charles , Andréassian Vazken
Published: March 2024

The use of machine learning (ML) methods in rainfall-runoff modelling has apparently led to better prediction, but there are some concerns about the interpretability of these models. The emergence of hybrid modelling, which couples the data driven approach with the classical physics-based conceptual approach, has shown promise in enhancing both interpretability and accuracy. ML models and conceptual models each come with their own modelling practices and habits. To develop a hybrid approach, it is necessary to consider them.While some of the steps in these modelling chains are similar (for instance the selection of the right metric during the calibration or learning step), others are more specifics, such as the optimization of the hyper-parameters of ML models. Furthermore, the hybrid approach comes with specific methodological challenges that emerge when coupling the two different types of models. For instance, depending on the choice made by the modeller, the parameters of the conceptual model are either trained with the ML model parameters or calibrated separately by a non-ML method.There is a need to better understand the variety of hybrid approaches and to estimate the impact of their methodological choices. This work is based on a literature review and on large-sample modelling experiments with hybridizations of two classical models running at different time steps: the monthly GR2M model and the daily GR4J model. 
Implementation of UNESCO’s Recommendation on Open Science through Outcrop Modelling in UNESCO Global Geoparks
Authors: Abreu Antonio , Sabo Rania , Vandenberghe Kristof , Lee Eunhee
Published: March 2024

Abstract In 2015, UNESCO adopted its third designation (UNESCO Global Geoparks) to promote the conservation, education, and sustainable development of Earth's geological features, aligning with one of its mandates – geoscience. In a significant development in 2021, UNESCO adopted the Recommendation on Open Science, the first international standard setting instrument on open science. This sparked a growing interest in the potential availability of geological data from Geoparks through open data sources.Geoparks face different challenges that demand an inclusive solution, and three-dimensional (3D) outcrop modelling emerges as a possible option for some of the issues, while allowing for the implementation of the UNESCO Recommendation on Open Science:It can assist in the conservation and sustainable management of geological resources, through providing an open-source platform for informed decision-making.
Addressing educational challenges, 3D models become interactive tools for virtual field trips, extending the reach of UNESCO Global Geoparks to a broader audience.
For geotourism, outcrop modelling enhances promotional efforts by showcasing unique geological features, attracting, and retaining visitors.
These models offer detailed insights into geological structures, aiding risk management application via proactive mitigation of hazards.
3D modelling overcomes accessibility limitations by enabling virtual exploration of otherwise hard-to-reach locations, fostering a more inclusive understanding of geological heritage.
The ease of sharing these models fosters collaboration among geologists and researchers, contributing to a collective knowledge base about geological formations located within UNESCO Global Geoparks.
Developing 3D outcrop modelling in Geoparks will require collaboration with a specialized organisation. Due to its proficient acumen in this domain, Deep-time Digital Earth (DDE) emerges as a compelling collaborator in this project. Working with DDE could allow the preparation of a digital inventory of interesting geological features and land/seascapes for a particular under-represented region, such as Africa. The implementation methodology is set to take place over a few phases, piloting selected UNESCO Global Geoparks. The first phase will include the identification of which UNESCO Global Geoparks are already implementing the technology and what is the interest of Geoparks in using this technology.Overall, it is expected that 3D outcrop modelling will be instrumental in overcoming various challenges, making Geoparks more accessible, engaging, and sustainable.
Low-frequency variability of synoptic-scale atmospheric circulation patterns in the Northern Hemisphere extratropics and associated hindcast skill of decadal forecasting systems
Authors: Brands Swen , Cimadevilla Ezequiel , Fernández Jesús
Published: March 2024

The inter-annual to multi-decadal variability of recurrent, synoptic-scale atmospheric circulation patterns in the Northern Hemisphere extratropics, as represented by the Jenkinson-Collison classification scheme, is explored in reanalysis data spanning the entire 20th century, and in global climate model (GCM) data from the historical, AMIP and DCPP experiments conducted within the framework of CMIP6. The aim of these efforts is to assess the effect of coupled vs. uncoupled and initialised vs. non-initialized GCM simulations in reproducing the observed low-frequency variability of the aforementioned circulation patterns.Results reveal that the observed annual counts of typical recurrent weather patterns, such as cyclonic or anticyclonic conditions and also situations of pronounced advection, exhibit significant oscillations on multiple time-scales ranging between several years and several decades. The period of these oscillations, however, is subject to large regional variations. This is in line with earlier studies suggesting that the extratropical atmospheric circulation’s low frequency variability is essentially unforced, except in the Pacific-North American sector where the forced variability is enhanced due to ENSO teleconnections. Neither the periods obtained from historical nor those obtained from AMIP experiments align with observations. Likewise, not even the periods obtained from different runs of the same GCM and experiment correspond to each other. Thus, in an non-initialized model setup, ocean-atmosphere coupling or the lack thereof essentially leads to the same results. Whether initialization and/or augmenting the ensemble size can improve these findings, will also be discussed.Acknowledgement: This work is part of project Impetus4Change, which has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101081555.
Drivers of the 2016 particulate matter pollution episode  over northern India
Authors: Agarwal Prerita , S. Stevenson David , R. Heal Mathew
Published: March 2024

Intense episodes of fine particulate matter (PM2.5) pollution often overwhelm large areas of the  Indo-Gangetic Plain (IGP) in northern India during the post-monsoon season, a time when crop residue burning is at its peak. We conduct idealised emission sensitivity experiments using the WRF-Chem model to investigate the leading causes and spatiotemporal extent of one such extreme episode from 31 0ct - 8 Nov 2016, when hourly PM2.5 levels exceeded 500 µg m–3across much of the IGP on several days. We utilise the anthropogenic emissions from EDGARv5.0 and the latest FINNv2.5 for fire emissions and evaluate modelled and observed ambient PM2.5 and black carbon  (BC) concentrations across the IGP. The model captured the PM2.5 and BC peaks during the latter half of the episode and underestimated on other days. We find that biomass burning (BB) emissions during this episode have the strongest effect across the source regions in the upper (NW) IGP, followed by Delhi (middle IGP), where it contributes 50 - 80 % to 24-h mean PM2.5. Complete elimination of BB emissions decreases PM2.5 concentrations by 400 µg m–3  (80 - 90 %) in the upper IGP and by 280 µg m–3  (40 - 80 %) across the middle IGP during this episode. Contributions from the BB source to daily varying BC concentrations are 80-90 %, 40 - 85 % and 10 - 60 % across upper, middle and lower IGP, respectively. BB emissions dominantly contribute to daily mean secondary organic aerosols (80 %), primary organic aerosols (90 %), dust (60 %), and nitrate (50 %) components of PM2.5 across the upper and middle IGP. In comparison, the anthropogenic share of these compounds was nearly one-third everywhere except across the lower IGP. The buildup of the episode across the middle IGP was facilitated by prolonged atmospheric stratification and stagnation, causing BB-derived BC and PM2.5 to be trapped in the lowest 1 km. Our work emphasises the need for rigorous policy interventions during post-monsoon to reduce agricultural crop burning, together with targeted anthropogenic emissions control across the IGP, to minimise such extreme episodes in the future. 
An efficient hybrid SBI-FD method for modeling fluid migration and fault-fluid interactions
Authors: Wang Yu-Han , Rafn Heimisson Elías
Published: March 2024

The interactions between fluids and fault structures play a pivotal role in understanding fault slip behavior. Over the years, various numerical methods have been developed to simulate these interactions. Volume-based methods, like the finite difference method (FDM), excel in their capacity to handle the intricacies of real-world fault structures, including material heterogeneity. On the other hand, the spectral boundary integral method (SBIM) is renowned for its computational efficiency. Recently, a hybrid approach has garnered significant attention, offering the benefits of both volume-based and SBI methods. This hybrid method allows for the consideration of fault structures' heterogeneity while maintaining computational efficiency. In this study, we introduce a novel hybrid method that bridges the SBIM and the FDM to model fluid migration in fault structures. Through rigorous model verification, we establish that our hybrid method can achieve a remarkable speedup of up to one thousand times compared to the FDM. Furthermore, we conducted two parametric studies to address open questions in fluid migration modeling within fault structures. First, we investigate the mobility contrast ratio between the host rock and the damage zone to determine the limits under which we can assume a zero-leak-off interface. Second, we explore the role of fault zone width in maintaining the validity of this zero-leak-off assumption. Building upon these foundational investigations, we demonstrate the possibility of extending the numerical framework to describe fault-fluid interactions considering poroelastic coupling.
Global assessment of tomographic resolution and uncertainty with the SOLA method
Authors: Freissler Roman , Schuberth Bernhard S.A. , Zaroli Christophe
Published: March 2024

Interpretations of seismic tomography and applications of the resulting tomographic images, e.g. for estimating present-day mantle temperatures, require information on their resolution and uncertainty. Assessing these model properties is often difficult due to the large size of tomographic systems on global scales. In consequence, there have been only few attempts to consistently analyse the spatially variable quality of tomographic images of deep mantle structure. For linear problems, both resolution and uncertainty can be quantified with the tools provided by classic Backus–Gilbert (B–G) inversion. In this theory, averaging kernels define the local resolving power at each model parameter, while uncertainties represent the propagation of data errors into the model values. By using a more efficient variant of B–G inversion, the method of 'Subtractive Optimally Localized Averages' (SOLA), global tomography can be performed with complete information for model appraisal.Based on the SOLA framework, we present a concept for the assessment of the 3-D resolution information contained in a global set of averaging kernels. It is based on the rigorous estimation of resolution lengths from a 3-D Gaussian parametrization of the averaging kernels, together with a test for the robustness of this approximation. This is a necessary step because a perfectly bell-shaped or delta-like behaviour of resolution can not always be guaranteed in global tomography due to the inhomogeneous data coverage. Therefore, we also develop a classification scheme, which enables a basic identification of those averaging kernels that are too complex to be sufficiently described by the chosen definition of resolution length. We note that this approach is more generally applicable, i.e. it can be used with any explicitly available set of averaging kernels or point-spread functions, but also with alternative parametrizations.In the context of the SOLA method, our resolution analysis can be further used to locally calibrate the inversion parameters. This involves on the one hand the specification of a target (resolution) kernel. On the other hand, a trade-off parameter needs to be selected that regulates the fit of the averaging to the target kernel, and the conversely affected propagation of data errors.To this end, we apply our concept for robust resolution estimation to different sets of averaging kernels from SOLA inversions with varying parameter combinations. Most notably, we systematically increase the spatial extent of the target kernels (taken as 3-D Gaussian functions here as well). The final maps of global (and classified) resolution and uncertainty can be viewed together for a complete picture of the model quality. They reveal where, and for which target size and amount of error propagation, resolution lengths are meaningful and model values can be interpreted appropriately.
Influence of ambient environment on dust grains detection by electric field instruments
Authors: Vaverka Jakub , Pavlů Jiří , Šafránková Jana , Němeček Zdeněk , Ijaz Samia
Published: March 2024

Dust grain impacting the spacecraft body can be either partly or totally evaporated and ionized as well as a small part of spacecraft material. A cloud of charged particles (impact cloud) generated by such impact can consequently influence the spacecraft potential and/or measurements of on-board scientific instruments. Electric field instruments are sensitive to these disturbances and typically register signals generated by dust impacts as short transient pulses. This method is commonly used for the detection of dust grains even without dedicated dust detectors.The presented study is focused on the influence of the ambient environment on dust detection for various designs of electric field instruments (probes/antennas) operating in the monopole and dipole configurations. An ambient plasma influences the spacecraft potential, which is crucial for charge separation and consequent propagation of the impact cloud. The plasma and solitary waves also affect dust detection by the presence of other pulses in the measured data. It is important to understand these effects to compare results obtained by various spacecraft in different environments.
On the Mechanisms Driving Latent Heat Flux Variations in the Northwest Tropical Atlantic
Authors: Fernández Pablo , Speich Sabrina , Bellenger Hugo , Lange Vega Diego , Karstensen Johannes , Zhang Dongxiao , Barbedo Rocha Cesar
Published: March 2024

The Northwest Tropical Atlantic (NWTA) is a region with complex surface ocean circulation. The most prominent feature is the North Brazil Current (NBC) and its retroflection at 8ºN that leads to the formation of numerous mesoscale eddies known as NBC rings. The NWTA also receives the outflow of the Amazon River, generating freshwater plumes that can extend up to 100,000 km2. These two processes affect the spatial variability of the region's surface latent heat flux (LHF). First, the presence of surface freshwater modifies the vertical stratification of the ocean limiting the amount of heat that can be released to the atmosphere. Second, they create a highly heterogeneous mesoscale sea-surface temperature (SST) field that directly influences near-surface atmospheric circulation. These effects are illustrated by observations from the ElUcidating the RolE of Cloud-Circulation Coupling in ClimAte - Ocean Atmosphere (EUREC4A-OA) and Atlantic Tradewind Ocean-Atmosphere Interaction Campaign (ATOMIC) experiments, satellite and reanalysis data. We decompose the LHF budget into several terms controlled by different atmospheric and oceanic processes to identify the mechanisms leading to LHF changes. We find LHF variations of up to 160 W·m2, of which 100 W·m2 are associated with wind speed changes and 40 W·m2 with SST variations. Surface currents or stratification-change associated heat release remain as second-order contributions with LHF variations of less than 10 W·m2 each. The results highlight the importance of considering these three components to properly characterize LHF variability at different spatial scales.
Extreme sea-level projections along European coasts for climate adaptation services 
Authors: Irazoqui Apecechea Maialen , Melet Angelique , Reffray Guillaume , Le Cozannet Goneri
Published: March 2024

Sea-level rise is one of the most hazardous climate-change impacts and is projected to trigger dramatic increases of coastal flooding frequency in Europe in the current century and beyond.  As such, adaptation-related effective decision making relies on the availability of authoritative and locally relevant information on future coastal sea-levels and their extremes, which include uncertainty quantification. However, current available sea-level projections are typically limited by either too low spatial resolution and therefore missing physical processes relevant at the coast, they account for only part of the sea-level signal (e.g. storm surges), and/or are typically limited to the downscaling of a single atmospheric model and therefore offer no quantification of the potentially significant inter-model uncertainty.   In response to this knowledge gap, we present a novel extreme sea-level (ESL) projection dataset which focuses on the North-east Atlantic region. The dataset consists of a CMIP6-forced multi-model ensemble of downscaled projections until the end of the century, generated with a regional 3-dimensional ocean model at ~7km resolution. As such, the model captures not only storm-surge and tide induced ESLs, typically captured in barotropic 2-dimensional models, but also accounts for the contribution of circulation and density-driven modulations to extremes. Therefore, the ensemble dataset offers an excellent opportunity to explore ESL drivers at different spatio-temporal scales, their projected future changes, and associated uncertainties.This dataset will help to advance scientific knowledge on climate-change induced coastal flood risk changes, but also to increase confidence in quantitative assessments of impacts of sea-level rise through its contribution to the Coastal Climate Core Service (CoCliCo), a decision-oriented platform which will inform users on present-day and future coastal risks, and which is currently under development as part of a European Union’s Horizon 2020 project.The CoCliCo project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101003598
Topology of turbulence within collisionless plasma reconnection
Authors: Hnat Bogdan , Chapman Sandra , Watkins Nick
Published: March 2024

Magnetospheric Multi Scale four-point satellite observations are used to characterize the magnetic field line topology within a single reconnection current layer. We examine magnetopause reconnection where the spacecraft encounter the Electron Diffusion Region (EDR). We find fluctuating magnetic field with topology identical to that found for dynamically evolving vortices in hydrodynamic turbulence. The turbulence is supported by an electron-magnetohydrodynamic (EMHD) flow in which the magnetic field is effectively frozen into the electron fluid. Accelerated electrons are found in the EDR edge where we identify a departure from this turbulent topology, towards two-dimensional sheet-like structures. This is consistent with a scenario in which sub-ion scale turbulence can suppress electron acceleration within the EDR which would otherwise be possible in the electric field at the X-line.
Modelling Global Crustal Deformations Induced by Geophysical Fluid Loading for Space-Geodetic Applications
Authors: Dobslaw Henryk , Wang Jungang , Dill Robert , Balidakis Kyriakos
Published: March 2024

With planet Earth being a deformable body, any geodetic marker attached to its crust exhibts slight motions in response to various geophysical forces. Prominent examples are the diurnal and semi-diurnal tides of the solid Earth, but also other periodic and non-periodic forces induced by mass transport divergence in atmosphere, oceans and the terrestrially stored water are deforming the Earth's surface and therefore displace any geodetic instrument attached to it. Based on a suite of different numerical model data-sets, the Earth System Modelling group at GFZ is routinely calculating both tidal and non-tidal surface deformations that can be readily applied as a priori information for the processing of space geodetic data. The model data-sets are publicly available as global grids with 3-hourly temporal sampling covering almost five decades from 1975 until present time.We present results from dedicated geodetic analysis experiments in order to demonstrate potential impact of such prior information on the GNSS-based coordinate estimates. We utilize data from 220 globally distributed IGS stations from 2005 until 2019 and apply the IGS repro3 strategies for the GPS daily precise orbit determination strategy. We apply non-tidal atmospheric and oceanic loading corrections from the ESMGFZ products on the (i) observation, (ii) normal equation, and (iii) parameter levels, and study the impact of such background models on the coordinate time-series of GNSS permanent stations and other associated parameters. 
The Earth Climate Observatory (ECO) space mission concept for the monitoring of the Earth Energy Imbalance (EEI)
Authors: Clerbaux Nicolas , Dewitte Steven
Published: March 2024

The Earth Energy Imbalance (EEI) is defined as the small difference between the incoming energy received by the Earth from the Sun and the outgoing energy lost by the Earth to space. Both the incoming solar and the terrestrial outgoing energy are of the order of 340 W/m² at the global annual mean level, while the EEI is of the order of 0.9 W/m². The EEI is accumulated in the Earth’s climate system, particularly in the oceans which have a high heat capacity, and results in global temperature rise.
Despite its fundamental importance, the EEI is currently poorly measured from space, due to two fundamental challenges.  A new space mission concept, called the Earth Climate Observatory (ECO) - with as primary mission objective the accurate and stable monitoring of the EEI - is currently elaborated.
The first fundamental challenge is that the EEI is the relatively small difference between two opposite terms with large and nearly equal amplitude. Currently, incoming solar radiation and outgoing terrestrial radiation are measured with separate instruments, which means that their calibration errors are added, and overwhelm the signal to be measured. In order to make significant progress in this challenge, a differential measurement using identically designed, intercalibrated instruments—so-called wide-field-of-view (WFOV) radiometers—to measure both the incoming solar radiation and the outgoing terrestrial radiation is needed.
The second fundamental challenge is that the outgoing terrestrial radiation has a systematic diurnal cycle. An adequate sampling of the global diurnal cycle can be obtained by using an innovative constellation of two orthogonal 90° inclined orbits which provide both global coverage and a statistical sampling of the full diurnal cycle at the seasonal (3-month) time  scale.
The wide-field-of-view radiometer will make accurate low-spatial-resolution measurements of the Total Outgoing Radiation (TOR) of the Earth. Auxiliary innovative multispectral visible and thermal imagers – with high information content, serving a multitude of possible secondary mission objectives - will be used to increase the spatial resolution of the radiometer observations and to separate the TOR spectrally in the Reflected Solar Radiation (RSR) and the Outgoing Longwave Radiation (OLR).
 
National-scale modelling analysis of drought characteristics and propagation under anthropogenic impacts in largest basins of China
Authors: haoran Hao , ningpeng Dong , mingxiang Yang
Published: March 2024

Understanding the drought evolution under changing environment is crucial to sustainable water management, especially for China where there are increasing anthropogenic activities. However, the extent to which human intervention affects the drought regime across China remains unclear. Here, we employ a national-scale land surface-hydrological model with representations of human water management and dynamic land use to investigate the impact of human activities on the drought regime across the largest river basins of China. We first identify the meteorological droughts and hydrological droughts of these basins using Standardized Precipitation Index (SPI) and Standardized Streamflow Index (SSI), respectively. Then, two controlled simulation experiments, namely the human altered scenario and the natural scenario, are designed to analyze the human impact on the frequency, severity, duration, recovery time, and recovery rate of hydrologic droughts, and the relationship between meteorological and hydrological droughts. Results indicate that the SSI variations under human impacts can be well simulated by the model, with a correlation coefficient ranging from 0.78 to 0.93. The basins in northern China generally sees a decrease in the number of drought events but an increase in the severity, duration, recovery time and recovery rate of hydrological droughts, and the average propagation time from meteorological droughts to hydrological droughts under the human impacts. For basins in southern China, the impact of human activities on the drought regime is similar to that of northern basins but to a lesser extent, possibly due to the larger streamflow in the south which diminishes the impact of human activities.
Comparing the accuracy of soil moisture estimation derived from environmental and spectroscopic gamma radiation measurements 
Authors: Akter Sonia , Huisman Johan Alexander , Bogena Heye Reemt
Published: March 2024

Continuous monitoring of root-zone soil moisture status is important to ensure the effective management of water resources for agricultural production, and to improve our understanding of land-atmosphere interactions in a changing climate. Utilizing gamma radiation to monitor soil moisture at the field scale is an emerging non-invasive technique that can also bridge the gap between point and remote sensing measurements. The measurement principle relies on the increased attenuation of gamma radiation emitted from soil with increasing soil moisture content. In a previous study, we successfully obtained soil moisture estimates from low-cost environmental gamma radiation (EGR) detectors. However, since EGR detectors provide the bulk response to gamma radiation over a wide energy range (0 to 3000 keV), EGR signals are influenced by several confounding factors, e.g., skyshine radiation, atmospheric and soil radon variability. To what extent these confounding factors deteriorate the accuracy of soil moisture estimates obtained with EGR is still not fully understood. Therefore, the aim of this study is to compare EGR measurements with K-40 gamma radiation (at 1460 keV) measurements that are much less influenced by these confounding factors. For this, two different kinds of gamma radiation detectors were installed close to each other at an agricultural field in Selhausen, Germany: an EGR detector based on a G-M counter tube (MIRA, ENVINET GmbH) and a spectroscopic scintillation-based detector (SARA, ENVINET GmbH). The field was also equipped with in-situ soil moisture sensors to measure reference soil moisture and a climate station to measure meteorological parameters. The EGR measurements were corrected for atmospheric radon-washout during precipitation events and the contributions of meteorologically influenced secondary cosmic radiation were also eliminated. In case of the spectroscopic measurements, no further corrections were applied as the analysis was only focused on the K-40 energy window. Both sets of gamma radiation measurements were related to reference soil moisture using a functional relationship derived from theory. We found that daily soil moisture can be predicted more accurately from K-40 gamma radiation (RMSE 4 vol.%) than from EGR (RMSE 6 vol.%). Regardless of the higher prediction uncertainty obtained due to the influence of the confounding factors at low energy, the long-term availability of ERG data, e.g., in Europe via EURDEP, makes it interesting for continental scale analysis of soil moisture. 
The Climate Potential of Garden Management: A Socio-Ecological Perspective
Authors: Teerlinck Janne , Wittemans Kelly , Dewaelheyns Valerie , Steen Trui , Somers Ben
Published: March 2024

Despite being one of the most densely populated and urbanized regions of Europe, 84% of Flanders' citizens have a garden, covering 12% of its territory. Research has shown that the collective network of domestic gardens could make a substantial contribution to climate change adaptation and mitigation, emphasizing their spatial and ecological importance as an integral part of the urban green infrastructure. Nevertheless, these private outdoor spaces are autonomously managed by many individual gardeners, often prioritizing aesthetics rather than environmental considerations. Understanding how people manage their gardens, and why, is thus crucial for unlocking the climate potential of gardens. This understanding can shed light on the current situation and identify opportunities for change. Unfortunately, limited research has been conducted on both garden management practices and the social drivers behind the decision-making process of individual gardeners. Therefore, our research aimed at unveiling current management practices and examining their variations across the urban gradient of Flanders. Through an online citizen science survey with a substantial sample size (n = 827) of Flemish domestic garden owners, we assessed garden management practices, as well as, motivations and self-reported knowledge. Potential cofounding factors such as personal, socio-economic and spatial context were also taken into account. Using a mixed model approach, we researched to what extent motivations, self-reported knowledge and context influence garden management decisions. Simultaneously, our analysis focused on variations of garden management practices across different urbanization levels, highlighting the intricate relationship between local contexts and the diverse ecological and social drivers influencing individual gardeners' decisions. By recognizing this interconnectedness, our findings offer insights that can inform urban planning and policy strategies to harness the untapped potential within these private green spaces. Ultimately, integrating social science into environmental studies is crucial for a comprehensive approach to addressing climate change and encouraging individual gardeners to adopt more climate-resilient practices.
On DAS-recorded strain amplitude
Authors: Forbriger Thomas , Karamzadeh Nasim , Azzola Jérôme , Widmer-Schnidrig Rudolf , Gaucher Emmanuel , Rietbrock Andreas
Published: March 2024

The power of distributed acoustic sensing (DAS) lies in its ability to sample deformation signals along an optical fiber at hundreds of locations with one interrogator only. While the interrogator is calibrated to record ‘fiber strain’, the properties of the cable and its coupling to the rock control the ‘strain transfer rate’ and hence how much of ‘rock strain’ is represented in the recorded signal.We use DAS recordings carried out with a Febus A1-R interrogator in an underground installation colocated with an array of strainmeters in order to measure the ‘strain transfer rate’ in situ. A tight-buffered cable and a standard loose-tube telecommunication cable (running in parallel) are used, where a section of both cables covered by sand and sandbags is compared to a section, where cables are just unreeled on the floor.Signals from the Mw 7.7 and Mw 7.6 earthquakes that took place on the East Anatolian Fault on February 6th 2023 allow us a proper comparison of signals in the frequency-band between 50 mHz and 0.2 Hz. At lower frequencies the DAS signal-to-noise ratio is insufficient. At higher frequencies the invar-wire strainmeters show a parasitic response to vertical ground motion. For frequencies up to 1 Hz we use seismometer recordings to estimate strain for an incoming plane wave, based on the ray parameter and in this way extend the bandwidth of the comparison. The ray parameter varies along the recording but is sufficiently well known and can be validated against the strainmeter recording.The ‘strain transfer rate’ is largely independent of frequency in the band from 0.05 Hz to 1 Hz and varies between 0.15 and 0.55 depending on cable and installation type. The sandbags show no obvious effect and the tight-buffered cable generally provides a larger ‘strain transfer rate’. The noise background for ‘rock strain’ in the investigated band is found at about an rms-amplitude of 0.1 nstrain in 1/6 decade for the tight-buffered cable. This allows a detection of the marine microseisms at times of high microseism amplitude.
The requirements for standardisation and performance evaluation for methane emissions monitoring technologies – a metrology perspective.
Authors: Robinson Rod , Innocenti Fabrizio , Helmore Jon
Published: March 2024

The goal of reducing anthropogenic methane emissions, in particular those arising from oil and gas operations, will require the implementation of routine and effective monitoring, both to detect repairable emissions and to reliably report emitted quantities. This will mean a transition from research investigations to more formal requirements for monitoring which will be the responsibility of industry. Methane emissions are particularly challenging to measure as the sources are highly inhomogeneous in terms of the ranges of their emission characteristics such as emission rate, temporal behaviour, and the wide variety of potential sources of emissions (ducted emissions, vents, fugitive leaks from components, storage tanks, flares, onshore and offshore facilities). To enable baselining and reliable reporting from across different parts of the oil and gas industry, and to address the different needs from detection to quantification, a range of different methods based on different measurement technologies are needed. This has resulted in a large number of available and developing approaches. Industry will need confidence in the emissions data they report as they will be used to guide emission reduction activities and to report into international frameworks such as the IMEO. In future there will be increasing regulatory pressure.   To support these growing requirements, and to support the selection of appropriate methods, there is therefore a need for a metrology framework to ensure the quality, reliability, comparability and suitability of measurement methods. It is important that the measurement uncertainties associated with methods are well understood including key sources of uncertainties, and the impact of the use of methods in different conditions and locations. This will not only support the selection of appropriate methods, but also enable the interpretation and comparison of data between sources and over different scales (both temporal and spatial).This talk will outline these issues, review the requirements for defining clear measurement objectives and performance requirements and provide an illustration of what such a metrology quality framework would look like.  The talk will discuss the issues around determining the uncertainties in methane emission measurements and in particular in derived data such as emission rates, and the use of validation studies and controlled releases will be discussed. It will also provide an overview of current activities to develop standardised methods for monitoring methane emissions and to develop the tools to support the evaluation of such methods.
Characterizing lightning-ignited wildfire occurrences at sub-grid scales in orography-aware NOAA/GFDL land model LM4.2
Authors: Wang Rui , Zorzetto Enrico , Malyshev Sergey , Shevliakova Elena
Published: March 2024

Lightning ignitions are the dominant causes of wildfires in many regions, responsible for 80% of burned areas at high latitudes and about 70% of fires in the Amazon rainforest. With global wildfire activities and extreme fire events (e.g., intensity, duration, and size) increasing under the changing climate conditions, understanding the interactions between lighting, landscape characteristics, and wildfires is crucial for predicting and mitigating the impacts of climate change. Cloud-to-ground lightning activities are driven by a combination of large- and local-scale factors, e.g., local atmospheric circulations and convection and topography. Furthermore, the number of lightning strikes is predicted to increase by 10 – 30 % per degree warming. Decadal satellite observations have revealed Earth’s lightning hotspots at very high resolution, however, there is a paucity of fine-scale lightning strikes and lightning-ignited wildfires (LIW) in the Earth system and climate models. Currently, many climate and ESM  models do not include fires at all or simulate them with meteorological inputs and grid-average lightning at the scale of atmospheric models (25 to 100 km), introducing large uncertainties of LIW due to the lack of information at the scales relevant to fire dynamics.  Lack of information about lightning trends and variability hinders the prediction and projection of fires and their contribution to carbon and other atmospheric tracers and global warming. For example, in the US National Oceanic and Atmospheric Administration (NOAA) Geophysical Fluid Dynamics Laboratory (GFDL) ESM4.1 model, the fire model uses a climatology of lightning strikes from preindustrial to 2100.In this presentation, we will demonstrate the implications of capturing subgrid lightning distributions in the GFDL land model LM4.2 for the global simulations of wildfire dynamics over the available records (1998-2013) and provide insights into future projections. LM4.2 captures sub-grid heterogeneity of land cover and use, soil geomorphology, and topography, facilitating the understanding of LIW distribution across global to regional and sub-grid scales. In this study, we leverage 0.1° × 0.1° lightning observations from the Lightning Imaging Sensor (LIS) and Optical Transient Detector (OTD) in the GFDL LM4-HB to characterize fine-scale lightning strike distribution and associated LIW.
The contribution of transport emissions to ozone mixing ratios in 2015 and 2050 in the Shared Socioeconomic Pathways (SSPs)
Authors: Mertens Mariano , Brinkop Sabine , Grewe Volker , Hendricks Johannes , Jöckel Patrick , Lanteri Anna , Matthes Sigrun , Righi Mattia
Published: March 2024

The transport sector (i.e. aviation, land-based transport and shipping) is an important source of emissions of ozone precursors such as nitrogen oxides (NOx), volatile organic compounds (VOCs) and carbon monoxide (CO). The formation of ozone from these precursors is a highly non-linear process which depends strongly on atmospheric background conditions (i.e., emissions from other sectors and meteorological conditions) and on the amount of transport emissions. As the different transport sectors emit at different geographical locations under different background conditions, their impact on tropospheric ozone cannot be estimated simply by comparing the emission shares. Instead, model-based spatially resolving approaches are needed that include a detailed ozone source attribution. To do this, we quantified for the first time the contribution of each transport sector to tropospheric ozone in a consistent way using the EMAC global chemistry-climate model equipped with an ozone source apportionment technique (called TAGGING). We performed simulations for present-day (2015) and for 2050 under the Shared Socioeconomic Pathways (SSP) SSP1-1.9, SSP2-4.5 and SSP3-7.0 and analysed the contributions of land-based transport from different geographical regions, shipping, and aviation to ozone. Based on these calculated contributions, we quantify the ozone radiative forcing (RF) attributable to emissions from the transport sector.For 2015, we estimate an ozone RF attributable to emissions from land-based transport, shipping and aviation of 121 mWm-2, 60 mWm-2, and 31 mWm-2,respectively. Compared to 2015, only SSP1-1.9 shows a strong decrease of ozone RF attributable to the entire transport sector in 2050. For the SSP2-4.5 scenario, we find similar RFs of the entire transport sector as for 2015, while the RFs in SSP3-7.0 increase compared to 2015.