bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative Analysis of SPI Index for Drought Conditions in North-West Bangladesh: A Study of CMIP6 Model Data and Machine Learning-Based Predictions
Authors: Sarkar Indronil , Islam Tamjidul
Published: March 2024

Rising global temperatures have been linked to changes in rainfall patterns and an increase in extreme rainfall-related weather events worldwide. Because of its fluctuating precipitation, Bangladesh, a nation susceptible to natural catastrophes, has experienced and will continue to confront more catastrophic calamities. Among these hazards, drought is a more concerning issue for an agriculture-dependent country like Bangladesh. This study has addressed this issue and analyzed the drought condition for the historical period (1985–2014) and near future (2025–2054) by estimating the SPI index in the north-west region of Bangladesh. In this study, an investigation has been done for future projections under various scenarios, such as SSP-245 and SSP-370, using seven suitable Coupled Model Intercomparisons Project 6 (CMIP6). Also, the SPI index has been predicted using a feed-forward backpropagation algorithm in an artificial neural network (ANN). This study has compared the results from two analyses (7 CMIP6 models) and machine-learning-based predictive output. For this study, the drought index was determined to be the Standard Precipitation Index (SPI) on three timescales: three months, six months, and twelve months. For the analysis, a three-layer artificial neural network model was used. In order to determine the most accurate predictive model for the SPI, this model was trained utilizing the SPI timescales with varying lag durations. The correlation coefficient indicated a high accuracy range (75%–85%) in predictive values, demonstrating the model's effectiveness. Additionally, the comparison of observed versus predicted curves for the SPI index across the three timescales also revealed similar trends. The SPI index, derived from 7 CMIP6 models, shows that in the near future, drought events for SSP-370 scenarios are more frequent than SSP-245 scenarios. For the historical period, Chirps precipitation data has been used along with CMIP6 model data, and it has also shown an increasing trend in drought frequencies with time. This study has analyzed the historical and future drought conditions, which can benefit policymakers by improving infrastructure for giving early warning to farmers and taking necessary precautions to protect the losses due to drought.
Development of a new computer tool for coupling HYDRUS-1D and MODFLOW
Authors: Balis Bartosz , Pawlowicz Mateusz , Szymkiewicz Adam , Simunek Jirka , Gumula-Kawecka Anna , Jaworska-Szulc Beata
Published: March 2024

Groundwater management relies increasingly on numerical models to assess past, present, and future conditions, optimize strategies, and protect resources from climate and land use changes. Groundwater systems encompass the unsaturated (vadose) and saturated (groundwater) zones, with vadose zone modeling presenting computational challenges due to nonlinear equations and complex parameters. One possible solution to include the vadose zone processes in groundwater models in a flexible manner is to couple computer programs modeling 3D flow in the saturated zone with programs modeling 1D flow in the vadose zone.  In this study, we introduce the HYDRUS-MODFLOW Synergy Engine (HMSE), a novel coupling approach for HYDRUS-1D and MODFLOW-2005, aimed at enhancing groundwater modeling. HMSE employs external coupling via a versatile interface, offering three deployment options: a desktop application, a Docker container, and a Kubernetes cluster. Users interact through a web interface, enabling project setup, model uploads, configuration adjustments, simulations, and result retrieval. The MODFLOW's area is divided into recharge zones, each assigned a HYDRUS-1D model representing soil profiles, land cover, groundwater depth, and weather conditions. HMSE offers two coupling modes. In the simple mode, groundwater table positions are assumed constant, HYDRUS-1D simulations are performed for the entire period, and average recharge rates are calculated for MODFLOW. In the second coupling mode, MODFLOW and HYDRUS-1D interact iteratively to update the water table position in HYDRUS-1D profiles after each stress period in the MODFLOW simulation. This involves splitting the MODFLOW model into segments corresponding to different stress periods, performing HYDRUS-1D simulations, passing recharge data to the RCH file, running a MODFLOW simulation for each stress period, and using MODFLOW results to calculate the average water table depth for each recharge zone, thus updating the corresponding HYDRUS profiles while avoiding oscillations in recharge flux.  HMSE combines the strengths of mature and validated HYDRUS-1D and MODFLOW-2005 programs, offering a more comprehensive understanding of groundwater systems. Our study presents a preliminary validation of HMSE for a shallow aquifer in northern Poland. We also evaluated HMSE performance in the three deployments (desktop, Docker and Kubernetes). 
Solid particle SAI with a fully coupled atmosphere-ocean-aerosol-chemistry-climate model SOCOLv4.
Authors: Sukhodolov Timofei , Vattioni Sandro , Stefanetti Fabrice , Schuring Iris , Sedlacek Jan , Chiodo Gabriel
Published: March 2024

Solid particles, such as alumina, calcite, and diamond, have been proposed as an alternative material for the stratospheric aerosol injection (SAI) studies. The traditional SAI set-up based on sulphate aerosols was shown to have several limitations such as stratospheric heating, due to absorption of long wave radiation, or ozone depletion, due to chlorine activation at the particle surfaces. Solid particles are thought to potentially overcome these limitations by having better optical properties and/or larger chemical inertness. In our work, we use for the first time a fully coupled atmosphere-ocean-aerosol-chemistry-climate model SOCOLv4.0, which incorporates a solid particle emission scheme, to assess the SAI effects of the alumina, calcite, and diamond. For each solid particle type, we followed the GeoMIP protocols and performed G4 and G6 experiments, which are cooling efficiency calibration runs and the transient ensemble runs to bring decadal surface temperatures of the SSP5 scenario to the ones from the SSP2 scenario, respectively. For all considered SAI substances, we find that the resulting burden is close to the yearly emission quantity, suggesting an average lifetime of approximately one year. Diamond has the highest burden-per-emission ratio, suggesting a higher lifetime, which is explained by its small particle radius. Sulfur, alumina, and calcite provide very similar cooling per emission, while diamond has a cooling efficiency of about a factor of three higher. Diamond also has the lowest absorption in the long wave, which allows it to show the weakest heating of the lower stratosphere, no increase in the stratospheric water vapour, and smallest dynamical effects on ozone. In terms of surface climate artifacts, those species that show the weakest heating in the stratosphere (calcite and diamond) also show the least anomalies in atmospheric and oceanic circulation patterns compared to the SSP2 scenario. Information on the interaction between alumina, calcite and ozone-relevant chemical cycles is available, but has not been sufficient so far for implementing their ozone chemistry with high confidence in the results. Additional laboratory studies, thus, are required for further modelling research on this subject.
The duration of injection protocol likely controls the maximum magnitude of induced earthquakes
Authors: Moein Mohammad JA , Langenbruch Cornelius , Shapiro Serge
Published: March 2024

High-pressure fluid injection into subsurface is often carried out to enhance the permeability of deep geothermal reservoirs. The operation sometimes triggers induced earthquakes that may be as large as natural earthquakes. Novel injection protocols such as cyclic injection schemes have been proposed to mitigate the risk of inducing larger events. Currently, the of impact cyclic injection schemes on the maximum magnitude Mmax is not fully understood. Here, the working hypothesis  is that the pore-pressure diffusion is the dominant triggering mechanism of induced events and the maximum induced earthquake scales with the pressure-perturbed fault size. We developed a first-order hydrogeological model and simulated the fluid injection into a porous rock with an embedded large-scale fault zone. Different injection scenarios were implemented, and the pressure-perturbed fault size was computed and translated to the maximum induced earthquake magnitude. The numerical models showed that the duration of the injection protocol plays an important role and likely controls the occurrence of larger-magnitude events. Our numerical models can provide significant insight into the effectiveness of mitigation strategies during the engineering of Enhanced Geothermal Systems and underground storage reservoirs.
Groundwater storage recovery in the North China Plain: Impacts of river replenishment, land use change, and climate variability
Authors: Xu Yuancheng , Long Di , Cui Yingjie , Dong Liang , Wada Yoshihide
Published: March 2024

The North China Plain (NCP) has faced substantial groundwater depletion driven by rapid population growth, socioeconomic development, and high irrigation water demand in recent decades. Responding to this challenge, the Chinese government has implemented significant measures, including the construction of the South-to-North Water Diversion Project's middle route (SNWD-M) and the curtailment of groundwater use, aiming to alleviate water scarcity and overexploitation. The river replenishment initiative, utilizing surplus SNWD-M water, has injected over 9.5 km3 into NCP rivers. Simultaneously, policy-induced shifts in agricultural land use, such as transforming winter wheat and summer maize rotation to single crops through seasonal fallow, have reshaped the landscape. Additionally, extreme events like the record flood in the summer of 2023 have become influential contributors to groundwater recharge in the NCP under changing climate conditions.To evaluate the joint impact of these anthropogenic and natural factors on groundwater levels and surface water-groundwater interactions, we established a coupled surface water-groundwater model across the NCP. Our findings reveal that river replenishment, coupled with the 2023 record flood, played a pivotal role in the rebound of groundwater levels. However, changes in agricultural land use introduce uncertainties. This study provides a holistic understanding of the drivers behind the recovery of groundwater storage in the NCP over the past decade, offering valuable insights for the enhanced management of the SNWD-M initiative.
Causes of large climate model spread in equatorial Pacific cloud feedback
Authors: Hill Peter , Finney Declan , Zelinka Mark
Published: March 2024

Climate models remain the best tools for predicting the impact of climate change on quantities relevant to human activity, such as precipitation, surface temperature and occurrence of severe weather events. Since many of these changes scale with the models equilibrium climate sensitivity, it is crucial to understand the differences in climate sensitivity between the models, which are primarily driven by inter-model differences in cloud feedbacks.Inter-model differences in cloud feedbacks are largest in the equatorial Pacific. Focussing on the area from 10°S - 10°N, and 160°E – 270°E, we find an inter-model standard deviation in cloud feedback of ~1.36 W m-2 K-1. Using appropriate weighting to account for the area of this region, this equates to a contribution to the global mean cloud feedback uncertainty of ~ 0.07 W m-2 K-1, which represents approximately 20% of the inter-model spread in global mean cloud feedback. Local differences in cloud feedback between models in this region are even larger and may have implications for regional circulation and precipitation changes. This region is also notable as an exception to the high correlation in cloud feedbacks between coupled and atmosphere-only models.In this presentation we will describe analysis of the causes of the inter-model spread in cloud feedbacks in this region. We shall demonstrate that the spread in domain-mean feedback in this region is due to inter-model differences in both dynamic and thermodynamic cloud feedbacks and show how this relates to changes in the properties of different cloud types amongst different models. We will also describe the use of empirical orthogonal function analysis to identify consistent cloud feedback patterns in this region across the ensemble of models and explain the causes of these patterns.
Aquatic eddy covariance pH and O2 fluxes, a technique for observing calcification in benthic ecosystems
Authors: Koopmans Dirk , Schaap Allison , Meyer Volker , Färber Paul , Queiss Lauren , Montilla Luis M. , Loucaides Socratis , Ahmerkamp Soeren , Cardini Ulisse
Published: March 2024

Calcifying organisms, including scleractinian corals and coralline algae, play a pivotal role in supporting benthic habitats and their associated ecosystem functions. However, many of them are threatened by ocean warming and acidification caused by anthropogenic CO2 emissions. Our understanding of their capacity to adapt to changes in their natural environment remains limited. To address this knowledge gap, we introduce a non-invasive method to quantify calcification from the simultaneous measurement of H+ ion and O2 fluxes utilizing the aquatic eddy covariance technique. Because calcification is a net source of H+ ions, it can be quantified as a source of H+ ions in excess of those generated by organic carbon metabolism. To examine the effect of ocean acidification on calcification by coralline algae epiphytes, we measured H+ and O2 fluxes at a seagrass meadow at a CO2 vent and at a control meadow, 670 m away. At both meadows we found that opposing flows were enriched in vent CO2. Additionally, vent CO2 diffused upwards through sediments at both sites. Because of this, we were unable to completely separate the calcification signal (non-metabolic H+ ion production) from the persistent background signal of vent CO2. However, we use these data as a demonstration of how H+ and O2 eddy covariance can reveal a subtle time-varying signal consistent with calcification in a benthic ecosystem. Based on the results of this study, H+ and O2 eddy covariance can quantify changes in benthic calcification over time, and therefore it can support better-informed management of scleratinian corals, coralline algae, and other benthic calcifiers. 
μGraphiline: a high-throughput, low-maintenance, fully automated 14C graphitization system
Authors: Tudyka Konrad , Kłosok Kacper , Jedrzejowski Maksymilian , Rakowski Andrzej , Pawełczyk Sławomira , Ustrzycka Alicja , Miłosz Sebastian , Kolarczyk Aleksander
Published: March 2024

μGraphiline is an innovative, fully automated graphitization system designed for radiocarbon dating using accelerator mass spectrometry. This system streamlines the conversion of samples into CO2 and subsequently into graphite. The standard configuration of μGraphiline is capable of preparing 24 targets daily, demonstrating its high throughput. It achieves a graphitization efficiency of over 95% for 1 mg graphite targets. μGraphiline also offers additional modules for stepped combustion, ramped pyrolysis, and oxidation, all of which can be operated at user-defined temperatures. Furthermore, its design ensures a low background and reproducibility, significantly enhancing the accuracy and reliability of radiocarbon measurements. One of the notable advantages of the system is its low maintenance requirements. It operates efficiently without the need for working gasses such as helium (He), argon (Ar), oxygen (O2), explosive hydrogen (H2) or liquid nitrogen, which simplifies its operation and enhances safety. This feature, coupled with its modular design and high efficiency, virtually no cross-contamination between modules and samples makes μGraphiline an advanced solution for radiocarbon dating. Lastly, the system's repeatability and reliability are backed by reference materials measurements from the International Atomic Energy Agency, demonstrating good repeatability.  This demonstrates μGraphiline's capability to deliver fast, consistent and accurate results, making it a valuable tool for various scientific and research applications.
Next-generation ASCAT surface soil moisture near real-time service
Authors: Hahn Sebastian , Wagner Wolfgang , Melzer Thomas , Vreugdenhil Mariette
Published: March 2024

The European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) has been operationally distributing a global Surface Soil Moisture (SSM) product derived from the Advanced Scatterometer (ASCAT) on board the series of Metop satellites since December 2008. The first Metop mission (Metop-A launched in October 2006) has been successfully concluded in November 2021, while two Metop satellites are still operational at the moment (Metop-B launched in September 2012 and Metop-C launched in November 2018), both providing an ASCAT SSM product in near real-time (NRT) sampled at 12.5 km and 25 km. EUMETSAT directly manages the ASCAT SSM NRT service, with the soil moisture processing chain implemented as part of the EUMETSAT Polar System (EPS) Core Ground Segment (CGS). In September 2015 the EUMETSAT Satellite Application Facility on Support to Operational Hydrology and Water Management (H SAF) formally took over the ASCAT SSM NRT product evolution and maintenance, while product generation stayed at the EUMETSAT EPS CGS. At that time, H SAF has already been responsible for the development and generation of the ASCAT SSM Data Record (DR) products, which consistently advanced through multiple algorithmic iterations in recent years. Beyond minor updates and occasional model parameter substitutions, the ASCAT SSM NRT products do not incorporate the latest algorithmic developments. Hence, a next-generation ASCAT SSM NRT service is currently being set up, aiming to enhance various aspects including spatial resolution and vegetation correction. The new service will run alongside the current NRT system, ensuring that users will experience a seamless transition.In this study, we introduce the scientific innovations and algorithmic updates of the upcoming H SAF ASCAT SSM NRT products sampled at both 6.25 km and 12.5 km. A validation was performed by comparing the old and new ASCAT SSM with other satellite soil moisture products, in-situ data, and soil moisture information derived from land surface models. The results show an improved performance particularly with respect to the capability of the data to characterise extremes. Furthermore, we will discuss product format changes, such as a new Discrete Global Grid (DGG) defining a more homogeneous sampling distribution of grid points on the Earth's surface.
Bridging the gap between plot and continental scale: A landscape scale greenhouse gas observation system based on a tall tower eddy covariance.
Authors: Kissas Konstantinos , Gorlenko Anastasia , Scheutz Charlotte , Ibrom Andreas
Published: March 2024

Due to its urgency, curbing greenhouse gas (GHG) emissions as fast as possible is pivotal for all countries. Mitigation measures are being initiated and a need for monitoring verification and reporting (MVR) of their efficacy arises. Currently existing science based MVR strategies are either too fine scale, e.g. traditional eddy covariance, or very coarse scale, e.g., atmospheric model inversion from high precision continental scale concentration fields. Integral methods to estimate GHG budgets of landscapes and cities are in the state of development. One element of such systems are turbulent flux measurements from tall tower platforms. To be able to document the green transition of Denmark in terms of reducing GHG budgets, we proposed a network of tall tower GHG flux measurements covering representative urban and remote landscapes. In the first step of the project, we designed and built a prototype of such system and applied it in a rural area close to the Danish Capital of Copenhagen.In this presentation, we define criteria for a successful tall tower based GHG flux observation system for MVR of a change in net GHG emissions. We provide a brief overview how we optimized the design to meet these criteria. Finally, we present some key results from the first five months of continuous observation to demonstrate how well we actually met the criteria with our system and conclude on the future prospects of the proposed tall tower GHG observation network.The results include net fluxes of all major long living GHG (CO2, CH4 and N2O) and two indicator gasses, i.e. carbonyl sulfide (COS) and carbon monoxide (CO). These indicator gases were chosen to represent photosynthesis and to estimate fossil CO2 fluxes from combustion processes. Important results are how accurate the data represent the landscape and what the detection limits for flux estimations of the different GHGs are.
Liquid water path derived from airborne observations over the sea-ice-free Arctic ocean
Authors: Mech Mario , Ringel Maximilin , Risse Nils , Crewell Susanne
Published: March 2024

Arctic Amplification is most evident in the rise of the near-surface air temperature observed in the last decades, which has been at least twice as strong as the global average. The mechanisms behind that are widely discussed. Many processes and feedback mechanisms still need to be better understood, especially those connected to clouds and their role in the water and energy cycle. Thereby, the cloud liquid water path (LWP) is an important cloud parameter, and it is important to know its occurrence and spatial variability. However, observing LWP is prone to high uncertainties, especially in the Arctic, leading to about a factor of two difference in satellite retrievals between microwave and near-infrared retrievals. Moreover, weather and climate models show significant differences in Arctic regions.Within this contribution, we will present LWP observations over the sea-ice-free Arctic ocean from measurements conducted during four airborne campaigns conducted within the framework of the "Arctic Amplification: Climate relevant atmospheric and surface processes and feedback mechanisms (AC)3" during the last years over the Fram Strait West of Svalbard. The LWP has been derived by statistical retrieval approaches based on brightness temperature measurements of the Microwave Radar/radiometer for Arctic Clouds (MiRAC) operated onboard the Polar 5 research aircraft of the Alfred-Wegener Institute for Polar and Marine Research (AWI). The consistent LWP product has been used in a comparison study to validate satellite estimates from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Advanced Microwave Scanning Radiometer 2 (AMSR2) and the one from the ERA5 reanalyses. It could be seen that the various products reveal a characteristic shape of the LWP distribution, but their overall performance varies with season and synoptic situations, i.e., ERA5 does not produce larger LWP values and an over- or under-estimation for specific flights and too high LWP values for MODIS and too low for AMSR2 during cold air outbreak events.
Changes in maximum and minimum runoff of Eurasian Arctic rivers during the climate change epoch
Authors: Kireeva Maria , Magritskiy Dmitriy , Frolova Natalia
Published: March 2024

The study is devoted to the analysis of daily time series of river runoff in the Arctic zone of Eurasia. Unique data on daily water discharges in the closing gauges of Arctic rivers were collected and processed in the package grwat (https://cloud.r-project.org/web/packages/grwat/index.html ), which identifies genetic components of runoff. As a result, 53 runoff characteristics were obtained for each of the 25 rivers flowing into the Arctic Ocean and the contribution of snowmelt, rainfall, and groundwater components to the total runoff was analyzed. Particular attention was paid to extreme characteristics - maximum water discharges of spring freshet, rain events and minimum 1, 5, 10-averaged discharges during summer and winter.The study of maximum water discharges has shown that, in general there are trends of decreasing annual maximums for both large and medium-sized Arctic rivers. This trend, however, is not yet statistically significant everywhere. The most intensive decrease in maximums localized in the Northern Dvina, Ob, and Yenisei rivers, for which flow regulation by reservoirs has a significant impact. For the Kolyma, Yana and Indigirka rivers, there are periods of increase in maximums and their decrease lasting 5-7 years, with a general tendency to increase during 1960-2001 up to 15-20%.In contrast, the minimum discharges with different averaging intervals increases by 25-56 % everywhere; this trend is presumably related to the general climate warming, increased infiltration and the role of groundwater flow, and for the rivers in the eastern part of the Arctic zone - to the degradation of permafrost.The study also included analysis of the runoff signature transformation in Arctic zone by every year, as well as on average for the modern and historical period. The typing methodology consisted in classifying hydrographs according to two main features: a) exceedance of maximum discharge relative to the average annual discharge b) the share of flood runoff volume in the total annual runoff. The analysis showed a noticeable increase in the frequency of occurrence of smoothed hydrographs on the rivers of the Arctic zone of the Asia-Pacific region, for some basins the number of such years increased by 1.5-2 times (Polui, Turukhan, Ob rivers).
Decadal monitoring of the soil CO2 outgassing activity of Vulcano Island, Aeolian Archipelago, Italy.
Authors: Inguaggiato Salvatore , Vita Fabio , Inguaggiato Claudio , Mazot Agnes , Cangemi Marianna
Published: March 2024

The Active cone of La Fossa caldera is a close conduit volcano affected by solphataric activity, manifested in the hot fluids released from fumaroles and the associated thermal anomalies in groundwater and exposed ground.The evaluation of the volcanic activity changes are inferred by the near real-time monitoring of soil CO2 fluxes diffused at the La Fossa Cone and the peripheral areas of Palizzi and Levante Bay and by the discontinuous monitoring of CO2 fluxes diffused by soil in areas around the CO2 continuous monitoring stations, La Fossa Cone, Palizzi and Levante Bay. In particular, three main changes in degassing activity were recorded in 2009, 2021, and 2022 and allowed us to evaluate in near real-time the level and duration of the exhaling crisis affecting the Island of Vulcano, by measuring the changes in mass and energy carried by the fluid release.The strong and deep input of volatiles released, in the last decades, from the underlying magma batch strongly modified the chemical composition of the shallow plumbing system, leading the system to an increase in the level of CO2 and energy over time.
Understanding flows and sediment dynamics in the Norwegian Trench: Insights from the RV Pelagia Expedition 2023
Authors: Enge Anna , Pietrzak Julie D. , Mienis Furu , Kraal Peter , van Prooijen Bram C.
Published: March 2024

The Norwegian Trench and Skagerrak form a major canyon that cuts through the Northern North Sea towards the Kattegat. The Norwegian Trench and Skagerrak influence the inflow of Atlantic Water into the northern North Sea and the outflow of fresher waters from the Baltic and the many river plumes around the North Sea that flow towards the Atlantic Ocean through the Norwegian Coastal Current (NCC). The Norwegian Trench and Skagerrak have a key role to play in the circulation, transport and exchange of freshwater and sediment, having a strong control on the circulation, water mass transformations and sediment dynamics in the northern North Sea. When the NCC interacts with the saline waters of the North Atlantic large mesoscale eddies from and dominate the circulation. We explore how these eddies interact with the flow around the canyon, and influence the exchange between the North Sea and the Atlantic Ocean. To do this we use unique observations from the Norwegian Trench taken aboard the research vessel Pelagia between May 26th and June 14th 2023 together with numerical models of the region. Uniquely the data include Conductivity Temperature Depth (CTD) measurements, velocities, box core samples and multicore samples from stations in the Norwegian Trench. It also includes results from onboard erosion experiments. Additionally, Argo float data highlight the large-scale circulation in the northern North Sea. We explore whether the high current velocities at the seafloor could be induced by eddies and topographically steered currents and their impact on sediment dynamics. 
GRAVHEDRAL: a novel gravity inversion method to unravel planets’ interior
Authors: Ghirotto Alessandro , Zunino Andrea , Armadillo Egidio , Mittelholz Anna , Fichtner Andreas
Published: March 2024

Suitable modelling capabilities paired with planetary-scale datasets provide fundamental information to unravel planets’ interior and evolution. Despite the key role and tremendous effort of decades of scientific missions in advancing the understanding of planets’ subsurface, knowledge about their crustal structures and processes shaping them is still limited. This is mainly due to a sparse record of return samples or meteorites, in addition to the scarcity of surface geophysical measurements. Planets’ crust is however a recorder of ancient geological events leading to nonhomogeneous 3D density distributions, expressed in the form of gravity anomalies. While on Earth combined geophysical data can inform on subsurface properties, for other planets such datasets are sparser, and orbiter-based gravity data is one of few or even the only global-scale source of information related to their interior. Developing an innovative modelling methodology suitable to exploit such orbiter-based data can help infer the 3D density distribution in planets’ crusts, providing key insights to reconstruct their geological history. Here we present GRAVHEDRAL, a fully non-linear 3D inversion methodology of gravity anomaly data suitable for both local- and planetary-scale studies and capable of addressing limitations of existing modelling strategies. Such limitations are related to the challenge of i) characterizing complex 3D density distributions, which are expected in actual geological scenarios, and ii) mitigating the non-uniqueness of the solution. Using GRAVHEDRAL, planets’ interiors (e.g., crust, mantle, etc.) are parameterized in terms of polyhedra with density contrasts expressed as high-order polynomial functions, whose gravity responses can be computed thanks to recently derived analytical formulae. The inversion scheme relies on the Hamiltonian Monte Carlo (HMC) method, a probabilistic approach that is currently gaining momentum in the geophysical community. Compared to other probabilistic approaches, the HMC strategy allows the model space to be explored more efficiently thanks to the gradient calculation of the posterior probability density of the model parameters (i.e., polyhedra node positions and/or density contrasts). Statistical analysis and uncertainty estimation on the model parameters can be performed from the collection of posterior models, enabling the appraisal of different probable geological scenarios to address the non-uniqueness of the solution. GRAVHEDRAL aims to provide the space science community with a flexible tool to help image the still poorly known 3D crustal density distribution of other celestial bodies of our solar system, allowing researchers to test the occurrence of Earth-like geological structures on other terrestrial planets and thus to decipher the reasons behind their different geological evolution.
The Use of Ground-Penetrating Radar for Mapping Peatland Subsurface in Afforested Peatland Restoration
Authors: Hughes-Dowdle Laura , Kulessa Bernd , Murray Tavi , Walker Jonathan , Low Rob , Cox Robin , Pickard Joey
Published: March 2024

Peatland afforestation and drainage are major causes of upland peatland degradation and have resulted in ongoing issues including increased flood risk, biodiversity loss, and carbon emissions. The last decades have witnessed increasing global investments in peatland restoration, as exemplified in South Wales. Here, the peatlands of Pen y Cymoedd coexist as the UK’s highest altitude windfarm and are being restored post tree-felling through a process known as ‘forest-to-bog’ restoration. Yet, there is a definite need to improve understanding of the impacts and effectiveness of these interventions, which can be gained through the mapping and representation of peatland structure and in particular, its ecohydrological properties.Traditional peatland investigations involving manual probing and coring are environmentally intrusive and time and labour intensive. However, recent studies have demonstrated that geophysical approaches such as ground penetrating radar offer an alternative approach, enabling peat depth to be rapidly surveyed over large areas. Afforested peatlands, however, present new challenges for both radar and probe-based approaches, for example, the presence of tree roots can obstruct the probe from reaching the true depth of the peat body and create complex reflectors on the radargram. There remains little guidance on appropriate use of ground-penetrating radar methodologies in afforested peatland settings, particularly on peatlands that have different hydrogeophysical properties resulting from various land use interventions.In this study, ground-penetrating radar surveys were conducted on peatland sites representing four different condition states: intact, afforested, felled, and restored. The surveys aim to map peat depth and explore the structure of the shallow subsurface. We adjust the parameterisation and processing flows involved in ground-penetrating radar surveys to determine the most appropriate approach dependant on peatland condition and the purpose of survey. Furthermore, by comparing reflection properties from different peatland sites which were selected to replicate the successive stages of forest-to-bog restoration, the structural changes caused by forestry and subsequent restoration attempts are revealed. This research will therefore help to inform operational best-practice and policy of peatland restoration, both within and beyond Wales.
Did the Vikings Trigger Dune Belt Formation in Saaremaa (Estonia)?
Authors: Luik Katre , Rivis Reimo , Suursaar Ülo , Tõnisson Hannes
Published: March 2024

This study delves into the intricate evolution of the Järve coast in Saaremaa over thousands of years, employing a comprehensive, interdisciplinary approach to investigate the complex interplay between climatic shifts, geological factors, and potential anthropogenic influences on dune formation. The study prompts a crucial question: could local dune formation have been influenced or triggered by the activities of human settlers, the Vikings, the Crusaders and eventually Hanseatic League trading.The study uses a multi-disciplinary approach, combining OSL and C14 analyses, cartographic and photographic materials, LiDAR-based relief analysis and GPR studies.Over the past 7000 years, sea levels have been dropping due to postglacial uplift. About 4-3.5 thousand years ago, the area rose from the sea due to the uplift rate of 2.3 mm/year, coinciding with a warmer climate. From 3.5-2.5 thousand years ago, sandy spits and barrier islands were formed, which were exposed to a wide sector from SW to SE. Continuous land uplift gradually connected the Järve area with the mainland of Saaremaa, impacting wave patterns and hindering ridge formation. The Järve beach, now exposed only to S and SE, faced climate cooling during the Little Ice Age (AD 1100-1800), resulting in the formation of foredune-ridge and dune complexes that partly buried former spits and ridges. Saaremaa has been, and still is, rich in forests. However, recent analysis of old documents, maps, and aerial photographs reveals extensive deforestation in the area, which probably began during the time of the Vikings. Deforestation escalated rapidly due to an increase in marine transport, as confirmed by the fact that in 1297, coastal forest cutting was prohibited by law in the Tallinn region because sailors struggled to recognise the islands. The recent discovery of Viking shipwrecks near the study area at Salme also indicates substantial human activity over an extended period, which may have triggered dune development. During the same period, dune development has been detected in several locations along the Estonian coasts, leading us to question how much human activities have contributed to this phenomenon.This study opens ways for further exploration into the interactions between human endeavours and natural forces, shedding light on the intricate dynamics shaping coastal landscapes. The findings not only contribute to our understanding of the Järve coast's evolution but also prompt broader considerations regarding the interconnectedness of anthropogenic activities and climatic factors in shaping coastal environments.
Multi-scale chemistry-transport modelling of the 2022 extreme Sahara dustevent over Paris
Authors: Kuznetsov Konstantin , Kumar Behera Abhinna , Chen Cheng , Litvinov Pavel , Dubovik Oleg
Published: March 2024

Mineral dust aerosol, predominantly soil-based particles, is a significant and ubiquitous component in the atmosphere, influencing both air quality and regional to global radiative balance. Accurately representing its impact at an urban scale, particularly with resolutions down to a few meters, remains challenging. To enhance our understanding of the global dust cycle, including transport, deposition, and the life cycle of dust aerosol, we adopt a multi-scale modelling approach. This study focuses on simulating the movement of Sahara dust across different scales: from the regional (Europe) to the urban (Paris).
For the regional scale analysis, we utilize the WRF-CHEM model, offering detailed insights into the movement of Sahara dust towards Europe. This model diverges from the conventional practice of using climatology data from inventories. Instead, we initialize and set boundary conditions for gas species and aerosols using CAMS reanalysis data, while ERA-5 reanalysis data provide the meteorological input. WRF-CHEM, an atmospheric chemistry model, incorporates the physics, chemistry, and morphology of dust aerosol, achieving a high resolution of 1km around Paris through a four-tiered grid nesting system (27 km², 9 km², 3 km², and 1 km²). The WRF model is refined hourly with ERA-5 data and every three hours with CAMS data at the boundary of the largest domain. Although the nested grids derive their initial conditions from their parent domain, they do not undergo further nudging.
On the urban scale, we employ code_saturne, a general-purpose CFD open-source solver developed by EDF R&D, to assess air flow and pollutant dispersion around buildings in central Paris. Outputs from the regional scale WRF-CHEM model serve as the initial and boundary conditions for these local scale simulations. A notable challenge in urban modelling is accessing complete and open building geometry data. OpenStreetMaps stands out as a comprehensive source for such geometrical data. To incorporate geometry from various sources (e.g., LiDAR measurements or shape files from the Institut Géographique National of France), we convert these into a point cloud format. This data then feeds into an internal mesh generator, based on the API of code_saturne, allowing us to create meshes with a spatial resolution of 2 meters near buildings and approximately 60 meters at the calculation domain's border. Comparisons with ground-based measurements show a qualitative alignment.
The leverage effect of experience: how flood frequency and perceived loss of control influence individual protective motivation
Authors: Köhler Lisa , Han Sungju
Published: March 2024

The last 2023 IPCC report draws attention to the change in the occurrence and frequency of weather extremes and natural hazards (Lee et al., 2023). It emphasizes the urgent need for climate change mitigation and adaptation to counteract the risks to life, nature, values, and societies. A recent study by Köhler et al. (2023) provides insight into the fact that frequent flood experiences increase the willingness to undertake protective actions at the individual level but simultaneously lead to decreased self-reported resilience. Still, there is a gap in understanding why frequent flood experiences influence protective motivation and what other factors play a role. Building upon this, this study explores the role of frequent experience in protective motivation and why more experienced people are more likely to adapt. Also, we introduce a measure for control experience, the individual's perceived efficacy in managing past flood situations, to understand the role of perceived resistance in affecting protective motivation. To meet this aim, we apply Protection Motivation Theory (PMT) from the field of psychology to understand how frequent flood events and control experiences influence coping and threat appraisal, two factors that have been shown to impact people's motivation to change behavior. Structural equation Modeling is used to detect processes and interactions between several variables in one model. The data comes from a survey in Saxony (Germany) in 2020. We find that both the frequency of experienced floods and the control experience increase threat appraisal but decrease coping appraisal. Threat appraisal could, therefore, be a channel through which flood experience positively influences protective motivation. The negative influences of flood experience on coping appraisal could limit this positive impact, at least to some extent. Our findings carry profound implications in understanding better the protective behavior of people who have undergone multiple flood events. We deliver crucial insights into how the frequency of experienced floods, perceived efficacy in managing past flood events, and individual protective behavior are related.  Citations:Lee, H., Calvin, K., Dasgupta, D., Krinner, G., Mukherji, A., Thorne, P., ... & Park, Y. (2023). IPCC, 2023: Climate Change 2023: Synthesis Report, Summary for Policymakers. Contribution of Working Groups I, II and    III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing  Team, H. Lee and J. Romero (eds.)]. IPCC, Geneva, Switzerland.Köhler, L., Masson, T., Köhler, S., & Kuhlicke, C. (2023). Better prepared but less resilient : the paradoxical impact of frequent flood experience on adaptive behavior and resilience. Natural Hazards and Earth System Sciences, 23(8), 2787–2806.
A three-species model of aeolian saltation incorporating cooperative splash
Authors: Chen Yulan , Pähtz Thomas , Tholen Katharina , Kroy Klaus
Published: March 2024

Most aeolian sand transport models incorporate a so-called splash function that describes the number and velocity of particles ejected by the splash of an impacting particle. It is usually obtained from experiments or simulations in which an incident grain is shot onto a static granular packing. However, it has recently been discovered that, during aeolian sand transport, the bed cannot be considered as static, since it cannot completely recover between successive impacts. This led to a correction of the splash function accounting for cooperative effects [1], which were shown to be responsible for an anomalous third-root scaling of the sand flux with the particle-fluid density ratio s, observed in discrete-element-method-based simulations of aeolian sand transport across six orders of magnitude of s [2]. The model by [1] represents the aeolian transport layer by two species: high-energy saltons that eject low-energy reptons upon impact. While it quantitatively captures measurements and the simulated sand flux scaling, it does not recover the scaling laws of the simulated transport threshold and vertical flux at the bed. Here, we improve the model by [1] by means of a three-species saltation model. The additional species, called leapers, represent the fastest reptons, ejected by saltons in rare extreme ejection events. Together, saltons and leapers quantitatively reproduce the threshold and sand flux scaling behaviors, whereas reptons are predominantly responsible for the vertical bed surface fluxes seen in the simulations.[1] Tholen, Pähtz, Kamath, Parteli, Kroy, Anomalous scaling of aeolian sand transport reveals coupling to bed rheology, Physical Review Letters 130 (5), 058204 (2023). https://doi.org/10.1103/PhysRevLett.130.058204[2] Pähtz, Durán, Scaling laws for planetary sediment transport from DEM-RANS numerical simulations, Journal of Fluid Mechanics 963, A20 (2023). https://doi.org/10.1017/jfm.2023.343
The Balance of Internal and External Drivers in Gas Giant Magnetospheres
Authors: Rutala Matthew J. , Jackman Caitriona M. , Fogg Alexandra R. , Murray Sophie A. , Owens Mathew J. , Tao Chihiro
Published: March 2024

The magnetospheres of the gas giants are characterized by strong planetary magnetic fields, rapid rotation, and an intriguing, but not fully characterized, mix of external (solar wind) and internal driving of magnetospheric processes, including the aurorae. Determining the balance between these internal and external drivers is made difficult by the limitations of single-spacecraft measurements, which represent the vast majority of all in-situ magnetospheric measurements and upstream solar wind measurements at the giant planets. Simultaneous in-situ measurements, upstream solar wind monitoring, and remote sensing (e.g. multi-wavelength auroral imaging), gives the best chance to characterize internal and external drivers. Such data have only been taken once, during the brief coordination of the Galileo and Cassini spacecraft at Jupiter. In lieu of a large dataset of simultaneous measurements, advances in our statistical understanding of the balance between these internal and external drivers have been made by leveraging models of either the solar wind, giant planet magnetospheres, or both.
In the coming years, additional in-situ data, upstream monitoring, and remote observations coordinated either between space- or earth-based observatories will provide more context for understanding the giant planet magnetospheres, including potential coordination between JUICE and Europa Clipper. In the meantime, improved statistical analysis of both models and data are our best tools to better understand these systems. To this end, we will present the Multi-Model Ensemble System for the outer Heliosphere (MMESH)-- a suite of analysis tools designed to improve the accuracy of solar wind propagation models at the outer planets by self-consistently quantifying modeling uncertainties and biases and forming ensemble models with estimated error. Robust ensembles models allow statistically meaningful analyses of the effects of various solar wind drivers on planetary magnetospheres and quantification of the extent of external control over giant planet magnetospheres. We will conclude by demonstrating the usefulness of these statistical techniques by showing early results of an investigation into external control over Jupiter's overall auroral power and discussing future applications and improvements of this technique.