bluuebunny/crossref_metadata_2025 huggingface dataset:
Unveiling eddy subsurface evolution combining in situ and remote-sensing observation in Lagrangian tracking
Authors: Barboni Alexandre , Dumas Franck
Published: March 2024

Since the development of altimetric eddy detection, numerous studies assessed that mesoscale eddies have a strong signature in surface and subsurface properties, but also on ocean-atmosphere fluxes and biogeochemical variables. However previous studies largely used a composite approach, greatly inhibiting the temporal variability analysis.
More recently, eddy Lagrangian tracking reveals marked temporal evolution in individual mesoscale structures. Seasonal variations in eddy-induced sea surface temperature (SST) anomalies were observed and linked with a modulation of the vertical mixing, while winter mixed layer depth (MLD) were observed to be strongly impacted by subsurface density anomalies. But this temporal evolution is complex, changing from one eddy to another, with interannual variability not yet properly documented.
The DYNED atlas gathers altimetric eddy observations in Lagrangian tracks over the Mediterranean Sea, in addition to vertical measurements from Argo floats, high resolution SST (CMEMS 1/120⁰) and ERA5 reanalysis ERA5 (1/4°) offering a continuous and joint time series from 2008 to 2021. The colocation of in situ and remote-sensing data reveals that subsurface anticyclones remain cold in surface for a longer time in summer and on the other hand surface-intensified anticyclones are warmer in winter. Winter mixed layer inside-eddy is impacted by both atmospheric flux variability and subsurface density anomalies. Eddy winter SST anomaly evolution also appears as an interesting proxy for eddy MLD evolution.
Mesoscale eddy subsurface evolution is complex, but the imbrication between air-sea fluxes, and heat content of the mixed layer offers a way to unveil eddy subsurface evolution. This is a further step in the retrieval of 3D structures at mesoscale, using only remote-sensing data and sparse Argo profiles.
Nucleation Mechanism of the 2022 Ms6.8 Luding Earthquake in Sichuan, China: Insights from Lithospheric Effective Elastic Thickness and Numerical Simulation
Authors: Wang Fan
Published: March 2024

On September 5, 2022, Luding County in Sichuan Province, China experienced a Ms 6.8 earthquake. It is of significance to investigate the deep geodynamics and nucleation mechanism of the Luding earthquake for seismic hazard analysis and earthquake monitoring and forecasting in this region. In this study, we utilized EIGEN6C4 Bouguer gravity anomalies and SIO V15.1 topographic data to calculate the effective elastic thickness, Te, of the lithosphere in the southeastern margin of the Tibetan Plateau by finite difference method. The results indicate  that the Luding earthquake occurred in a gradient zone with a steep change in Te between the eastern edge of the Tibetan Plateau and the Sichuan Basin, and that Te changes significantly, increasing from approximately 0-10 km in the west to about 10-30 km in the east. Based on the rheological structure information provided by Te , we constructed a two-dimensional numerical model to study the distribution of strain energy and displacement vector fields in the region. The results reveal that lower crustal flow is the key factor of the Luding earthquake nucleation. The lower crustal flow in the eastern edge of the Tibetan Plateau, impeded along the Shimian-Mianning-Xichang segment , migrates upward along the strong and weak lithospheric interface between the Sichuan-Yunnan rhumb block and the Gongga Mountain blocks, resulting in the gradual accumulation of stress and strain energy in the transitional zone between the upper and middle crust. This, in turn, triggers fluid migration upwards, facilitating the rupture of shallow rocks and the nucleation of the Luding earthquake. Drawing insights from Te and numerical simulation results, we proposes a plausible deep geodynamic model for the nucleation of the Luding earthquake and analyzes the seismic hazard of the Shimian-Mianning-Xichang segment along the Juanshui River-Anning River fault.
Characteristics of the pre-monsoon cyclone over the Bay of Bengal in the last six decades
Authors: Jena Biswajit , Pattnaik Sandeep
Published: March 2024

The present study aimed to investigate the interdecadal variations in tropical cyclones (TC) and key large-scale atmospheric parameters that influence the characteristics of cyclones, including track, frequency, and intensity over the Bay of Bengal (BoB) during the pre-monsoon season (PMS) from 60 years of data. It is found that the frequency of TCs crossing the east Indian coastal landmass has increased in the recent decade (2013–2022) compared to the past five decades (1963–2012). The percentage frequency has increased in the recent ten years by 50% compared to the past fifty years. Easterlies are stronger at low-level, the interaction of easterlies and westerlies at east Indian coastal belts at mid-level, and the shifting of the upper-level jet stream to the lower latitude in the recent decade gives a clear signature that the path of the TCs has shifted from north (N)-northeast (NE) to the northwest (NW), i.e., towards east Indian coastal landmass, compared to past five decades. An anomalous low-pressure zone has prevailed over the NW India and Pakistan regions, which created a favorable path for the TCs to head towards the Indian subcontinent in the recent decade in contrast to the previous five decades. It is also noted that TCs have been more intense in the recent decade than the past five decades due to the rise in low- and mid-level specific humidity (SPH) and temperature over BoB. The findings of this study have immediate implications for forecasting agencies as well as other organizations, particularly in the coastal states of east India, where variations in the TC's characteristics can be used for planning and policymaking to create an infrastructure and society that are more resilient.
Air Quality Issues Associated with Wildfire Events in the Indian Himalayan Region  
Authors: Prabhakaran Anandu , Srivastava Piyush
Published: March 2024

In recent decades, the Indian Himalayan states have witnessed a notable surge in wildfires exacerbated by a confluence of anthropogenic and natural factors with the changing climate. While wildfires have long been a cause for concern, the associated air quality issues have garnered less attention than the winter smog resulting from stubble burning in North India. Noteworthy instances of North Indian wildfires occurred in 2016 and 2020, particularly impacting the state of Uttarakhand, where over 4000 hectares of forested land were engulfed. Beyond the immediate devastation caused by the fires, the dispersion of ashes and aerosols to adjacent Himalayan regions has become a pertinent concern. In this study, we utilize the NOAA-HYSPLIT model ensemble trajectories to illustrate the transport of wildfire pollutants vividly. A comparative analysis of the HYSPLIT model's forward trajectory with MERRA2 datasets reveals the transport of pollutants such as SO2EMBB (SO2 Biomass Burning Emissions), BCEMBB (Black Carbon Biomass Burning Emission), and BCSMASS (Black Carbon Surface Mass Concentration) as the wildfires progressed for 2016 and 2020 towards the Greater Himalayan region. Further abrupt peaks in BCSMASS, BCEMBB and SO2EMBB were noticed over the Greater Himalayan region, where the back trajectory projects to the fire ignition pixels as source points in the Uttarakhand region via FIRMS (Fire Information for Resource Management System) database. Noticeably, during the 2020 wildfire season, reanalysis datasets from ERA5 and NCEP-FNL show an abrupt variation of 4oC more compared to the normal skin temperature in non-wildfire seasons, whereas the 2016 wildfires were exacerbated by the heatwaves and El-Nino conditions in the Indian terrain. This alarming prospect parallels the 2019 Arctic Circle fire, emphasizing the urgent need for comprehensive strategies to mitigate the escalating impacts of wildfires on the fragile Himalayan ecosystem. 
Granite waste produced in quarries exploitation in northern Sardinia (Italy): recycling chances within the context of Critical Raw Material supply
Authors: Aquilano Antonello , Marrocchino Elena , Vaccaro Carmela
Published: March 2024

The Sardinia region has a longstanding tradition in ornamental granite extraction, reaching its production peak in the 1990s when it became Italy's leading granite producer, accounting for 90% of the national production [1]. However, the industry faced a decline starting from the mid-2000s due to the entry of other competitors into the global market and due to significant infrastructure issues on the island [1]. The 2008 financial crisis further reduced global granite demand and in the subsequent years, compounded by the events of the COVID-19 pandemic, prolonged the crisis in the sector. In Italy, granite production plummeted from over 2 million metric tons in 2011 to just under 200,000 metric tons in 2022 [2].Granite extraction has a striking impact on the Sardinian landscape, with landfills of granite blocks, visible from kilometers away, contributing to significant landscape degradation. These, in addition, affect plans to develop the unique archaeological sites of the Domus de Janas and contribute to soil depletion. The European Critical Raw Materials Act to future supply chains is crucial for Europe's green and digital transition, in line with the European Green Deal that identified recycling as part of the supply solution. In this context, recognizing potential opportunities for recycling these waste materials could aid in advancing the objectives of the European Union, enhance the aesthetic quality of the Sardinian landscape, and contribute to revitalize the granite extraction industry in Sardinia.This study focuses on the circular economy in a granite quarry located in the municipality of Buddusò (province of Sassari, Sardinia). Active for about 40 years, this quarry has accumulated significant amounts of granite waste from which feldspar, quartz and rare earth elements can be extracted. This research presents the results of geochemical, petrographic, and mineralogical analyses conducted on granite waste samples from the quarry under study. In addition, potential recycling solutions for this material in the context of Critical Raw Material supply are discussed.References:[1] Careddu, N.; Siotto, G.; Marras, G. The Crisis of Granite and the Success of Marble: Errors and Market Strategies. The Sardinian Case. Resources Policy 2017, 52, 273–276. https://doi.org/10.1016/j.resourpol.2017.03.010.[2] Istituto Nazionale di Statistica - Istat. Production in Value and Quantity per Single Product - Granite and Similar Rocks, Rough, without Shape. Accessed 18/12/2023. https://esploradati.istat.it/databrowser/#/it/dw/categories/IT1,Z0600IND,1.0/IND_PRODUCTION/DCSP_PRODCOM/IT1,115_168_DF_DCSP_PRODCOM_2,1.
New insights into the current dynamics of Thwaites and Pine Island Glaciers, West Antarctica.
Authors: Gudmundsson G. Hilmar , Morlighem Mathieu , Goldberg Daniel , Barnes Jowan , De Rydt Jan , Rosier Sebastian
Published: March 2024

We provide a summary of new insights into the contemporary dynamics of Thwaites and Pine Island Glacier, West Antarctica, obtained through series of recent modelling studies.  By conducting ice-flow modelling studies with three independent models (ISSM, StreamIce, Úa), all initialized to current day conditions, we show that all models provide very similar future estimates of future mass loss for a given forcing scenario. Importantly, while description of basal processes does impact our results to some degree, we nevertheless find that estimates of mass loss over time scale of 50 to 100 years, are insensitive to the choice of basal sliding law. This can be understood to be related to the compensating impact of the initialisation process that in each case produces correct initial state for the ice sheet (i.e. surface velocities and current rates of mass loss) irrespectively of the sliding law used. Furthermore, we find that inversion produces (e.g. estimates of basal slipperiness and englacial ice rate factors) can be exchanged between models, showing that these products are to large degree model independent. A common feature found in all our ice-flow studies, and coupled ice+ocean studies, is the existence of multiple tipping points within the Thwaites and Pine Island system. In all our ice-flow simulations, the grounding line of Thwaites always becomes unstable once it has retreated by about 75km upstream from its current position. We also conclude that the grounding line of Pine Island Glacier has recently undergone a phase of irreversible retreat, and that the glacier has at least 3 further tipping points that can be crossed in the near future (centennial time scale). Additionally, the western ice shelf of Thwaites has been dramatically weakening over the past decade and we used our three independent models to assess the effect of a potential complete collapse of Thwaites’ floating extension. First, we find that this ice shelf provides limited buttressing, and disintegrations of the ice shelf, in its current configuration, will not significantly impact upstream grounded. Second, it has been suggested that Thwaites would be subject to the Marine Ice Cliff Instability (MICI) if its ice shelf collapses, as it would expose a tall ice cliff. Using recently proposed cliff-height dependent calving laws, we find no indication that such calving laws give rise to an irreversible or unstable calving-front retreat.  Thus, those calving laws do not lead to a marine ice cliff instability despite prescribing calving rates as strongly increasing functions of cliff height.
Exploring fault parameters impact on tsunami modelling on strike-slip faults off SW Iberia
Authors: Martínez-Loriente Sara , Prada Manel , Macías Jorge , Sánchez-Linares Carlos , Gaite Beatriz , Puertas Luis Carlos , Perea Hector
Published: March 2024

The southwestern Iberian margin is one of the most seismogenic and tsunamigenic areas in Western Europe, witnessed through historical and instrumental catastrophic occurrences such as the 1755 Lisbon and 1969 Horseshoe events. This region, marked by the convergence of the African and Eurasian plates, undergoes structural deformation mainly accommodated by thrusts and strike-slip faults, which conform a 600 km-long and 300 km-wide deformation band named the SWIM Fault Zone. Previous studies that evaluated the sensitivity of tsunami impact on the SW Iberian coast to the fault geometry and slip distribution for local earthquakes, revealed that the SWIM strike-slip faults seem to be threatening faults for the Spanish coasts due to their orientation, extension and proximity to the shoreline.This study focuses on the two most prominent SWIM lineaments, the North (LNF) and South (LSF) strike-slip faults, to assess the effects of varying fault parameters on tsunami modelling. Parameters under scrutiny encompass fault dip, rake, seismogenic depth, and slip, with parameter ranges drawn from a comprehensive dataset comprising: a) multiscale multichannel seismic profiles and high-resolution bathymetry, enabling detailed characterization of the tectonic structures and fault plane construction; b) two regional wide-angle seismic sections spanning both faults, providing insights into the deep structure and physical properties along the fault planes, from which we derive slip values; and c) regional seismicity data, providing insight into the seismogenic depth and confirming seismic activity along both faults.This comprehensive investigation aims to deepen our understanding of how different fault parameters impact tsunami modeling, leveraging a robust dataset derived from multiple sources. The study's outcomes hold the potential to refine risk assessment methodologies and enhancing preparedness strategies for tsunami hazards along the southwestern Iberian coast.
Assessing the impact of behavioural interventions in reducing air pollution: A meta-analysis   
Authors: Suryanarayanan Uday
Published: March 2024

Keywords: Behavioural change, Behavioural intervention, Air pollution, Meta-analysis, Mission LiFE, Intervention strategy
Abstract
In India's Indo-Gangetic Plain (IGP) region, individual or household-level behavioural patterns are responsible for the emissions from the three leading sectors- residential energy use, transport, and waste burning, contributing 43 per cent to the pollution load. Therefore, behavioural change is critical to reduce air pollution in this region. Taking cognisance of this behaviour-pollution nexus, the Indian government launched Mission LiFE in 2022 to nudge individuals, communities, and institutions to practise environment-friendly actions. Behavioural intervention is a cost-effective option for a lower-middle-income economy like India to change polluting behaviours. A behavioural intervention redesigns the social, physical, or psychological environment where people make decisions without forbidding any options or significantly changing their economic incentives. Even though multiple randomised controlled trials (RCTs) have evaluated the impact of behavioural interventions on changing air pollution-contributing behaviours, very few meta-analyses of such RCTs that cover a wide range of behaviours and intervention strategies exist. A meta-analysis helps clarify which polluting sectors to target with which strategy. With this information, the public sector can target polluting behaviours effectively in India under Mission LiFE. Therefore, this meta-analysis aims to fill that knowledge gap by identifying which strategies will yield the maximum impact across the three leading polluting sectors in the IGP region. Providing comparative information about the non-polluting behaviours of close others and altering the physical environment produce the highest impact at the population level when targeting residential energy use and waste recycling. On the other hand, the mere provision of information via helpful tips, air pollution-related statistics, in-home displays, or energy efficiency labels is an ineffective strategy across sectors. Amongst all the sectors, targeting increased waste recycling produces the highest impact. With limited evidence emerging from Asia, Africa, and Latin America, these results provide a basis for designing pilot behavioural interventions in the Indian context, which will serve the twin objectives of generating ground-level evidence and driving behavioural change.           
Interpretable Baseflow Segmentation and Prediction Based on Numerical Experiments and Deep Learning
Authors: yu qiying , Hu Caihong
Published: March 2024

Baseflow is a crucial water source in the inland river basins of high-altitude cold regions, playing a significant role in maintaining runoff stability. Analyzing the impact of climate change and underlying surface conditions on base flow, based on scientifically separating baseflow, is helpful for maintaining river ecological health and rational water resource allocation, especially in severely water-scarce high-altitude cold regions. The challenge lies in selecting the most suitable base flow separation method in data-scarce high-altitude cold regions, qualitatively analyzing the effects of climate factors and underlying surface changes on baseflow values and seasonal distribution characteristics, and providing interpretable scientific predictions for baseflow changes. Therefore, this study aims to contribute further to cold region hydrology by addressing the gap in understanding how meteorological factors and underlying surface changes under the backdrop of climate change affect base flow more reasonably and comprehensively. The study introduces the Grey Wolf Optimizer Digital Filter Method (GWO-DFM) for rapid baseflow separation, utilizes the Long Short-Term Memory (LSTM) neural network model for scientific base flow prediction, and explores the interpretability of the LSTM model in base flow forecasting. The proposed method was successfully implemented using a 63-year time series (1958-2020) of flow data from the Tairan River basin in the high-altitude cold region, along with 21 years of ERA5 meteorological data and MODIS data (2000-2020). The results indicate that: (1) GWO-DFM can rapidly identify optimal filtering parameters, and compared with three other methods (Eckhardt filter, Boughton-Chapman, and Chapman-Maxwell), the average base flow separation using GWO-DFM as the best method for the high-altitude cold region significantly increased after the second baseflow rate mutation. (2) Baseflow sources are mainly influenced by precipitation infiltration, glacier frozen soil layers, and seasonal ponding. (3) Solar radiation, temperature, precipitation, and NDVI are the primary factors influencing base flow changes, with Nash-Sutcliffe efficiency coefficients exceeding 0.78 in both the LSTM model training and prediction periods. (4) Changes in base flow are most influenced by solar radiation, temperature, and NDVI.
Quantifying the Greenhouse Gas Emission and Nitrogen Losses in the Rice-Wheat Rotation System in the Tai Lake Basin, China
Authors: Zhu Minye , Gu Chuanhui , Gao Yufan
Published: March 2024

Rice paddy ecosystems contribute greatly to the anthropogenic greenhouse gas (GHG) emissions and reactive nitrogen (Nr) losses. Understanding the impacts of agricultural management practices on GHG and N losses is critical for implementing optimal farming practices and maintaining agricultural productivity. This study examines the influence of agricultural management on GHG and N losses in Tai-Lake Paddy soils of China using the Denitrification-Decomposition (DNDC) model.   The DNDC model was validated through the field experiment conducted in Changshu, China. A regional model was constructed for the entire Tai-Lake watershed. Sensitivity analysis was conducted using single-factor analysis.
 To comprehensively analyze combined carbon and nitrogen footprints and economic benefits, multiple quantitative indicators, including Net Global Warming Potential (NGWP), Total Nr losses (Nrloss), Carbon Footprint (CF), Nr Footprint (NrF), and Net Economic and Environmental Benefits (NEEB), were calculated. 
The results indicate that the DNDC model can accurately simulate the yield and total greenhouse gas emissions during the wheat-rice rotation period in the target farmland. The NGWP for the Tai Lake Basin ranges from 6035 to 12104 kg CO2-eq/hm2, and Nrloss ranges from 227.37 to 380.82 kg N-eq/hm2. The sensitivity analysis results indicate a positive correlation between CF and Nrf with fertilizer amount, soil pH value, soil organic carbon content, clay proportion, and precipitation. Among these factors, the fertilizer amount has the most significant impact on CF and Nrf, followed by pH. Additionally, the NEEB index is negatively affected by higher fertilizer amount and pH. Other factors have no significant effect on NEEB. Based on these results, it is recommended to reduce the fertilizer amount in agricultural production and maintain a relatively acidic soil pH level. This approach may can help reduce GHG and nitrogen loss, while improving the NEEB.
Thermodynamic control of microbial turnover of organic substrates in soils
Authors: Miltner Anja , Kästner Matthias , Maskow Thomas , Lorenz Marcel , Thiele-Bruhn Sören
Published: March 2024

Microbial turnover of organic substrates is a key process in soil organic matter formation and turnover. As microorganisms require both carbon and energy for growth and maintenance, carbon and energy fluxes in soils are tightly coupled. On the level of cellular metabolism, the substrates have to be allocated to catabolism and anabolism according to the requirements of the cells. In the soil system, additional processes have to be considered such as multiple substrate use, recycling of biomass components, interaction between different organisms and abiotic processes. As most of the energy flux in catabolism is created by the reduction of the terminal electron acceptors, the availability of the electron acceptors strongly affects carbon use efficiency and energy use efficiency. Here, we present a thermodynamic concept that combines experimental approaches of calorimetry and turnover mass balances paving the way for a better understanding of microbially mediated organic matter turnover and stabilization in soil.Mass balances in soil systems need to be set up for exemplary substrates using isotope labelled compounds. They should be combined with information on energy fluxes, which can be obtained using calorimetric methods for thermodynamic calculations. Recently, calorimetric methods have been introduced into soil studies, e.g. differential scanning calorimetry or isothermal reaction calorimetry. Alternatively, enthalpies of combustion or formation must be known or estimated, e.g. based on the nominal oxidation state of the substrates and reaction products. All of these methods have their strengths and weaknesses, which need to be considered when assessing and interpreting the results. From a thermodynamic perspective, it is crucial to define the system boundaries and to use thermodynamic state variables such as reaction enthalpy, entropy and Gibbs free energy. If applied properly, the predictive power of thermodynamics can be fully utilized for process evaluation. In particular, this approach will enable us to identify whether a particular process is thermodynamically feasible or not under the given conditions.In summary, linking mass balances and thermodynamics will allow us to better understand and predict soil organic matter turnover and sequestration.
First results from the high-density 4D GPR datasets acquired on three Swiss alpine glaciers using our drone-based GPR system.
Authors: Ruols Bastien , Baron Ludovic , Klahold Johanna , Morin Alexi , Francey Mélissa , Irving James
Published: March 2024

Drone-based ground-penetrating radar (GPR) has emerged as a valuable tool for safe and efficient acquisitions of unprecedented 3D and 4D high-density GPR datasets over alpine glaciers. Between the summers of 2022 and 2023, we obtained 4D datasets from three Swiss alpine glaciers, each serving distinct research objectives.
First of all, on the Otemma glacier, we collected the most extensive 3D/4D high-density datasets ever acquired on an alpine glacier, which primary goal is the investigation of internal glacier hydrology. Then, on the Findelen glacier, we conducted identical acquisitions five times regularly over a span of fourteen months, aiming to study the glacier’s internal dynamics. And finally, on the Rhône glacier, we acquired four datasets on a monthly basis over a large collapse feature that evolved during the summer of 2022, in order to understand better such mechanism.
This presentation aims to introduce the preliminary results from the analysis of these datasets, with a particular emphasis on the latest findings from the Rhône glacier dataset.
Snowfall over the Andes: a convection-permitting climate model
Authors: Potter Emily , Li Sihan , Jones Julie , Irarrázaval Íñigo , Matthews Tom , Perry Baker , Ely Jeremy
Published: March 2024

The Andes has the longest mountain range in the world, stretching over 7000 kilometres from Colombia in the tropics to the bottom of Chile in the extratropics. Millions of people depend on water supply from the Andes for their consumption, agriculture, hydropower, and ecosystem services. Often, this water comes from snow and glacier melt, and these water stores can be especially important in times of drought, or during dry seasons for regions with strong annual cycles of precipitation. The inaccessibility of the higher regions in Andes makes setting up weather stations difficult, and the extremely complex topography leads to sharp gradients in weather and climate with varying altitudes of snowline, therefore requiring very high-resolution models to accurately capture the small-scale processes occurring. Due to these challenges, snowfall and snowcover in the Andes remain poorly understood and difficult to model, which are critical to address in the face of a changing climate, with potential for future precipitation occurring in fewer, more extreme snowfall events.Here we present initial work optimising a high-resolution climate model over the Andes from Peru to the bottom of Chile. We have determined the best setup to model snowfall over the Andes in the Weather Research and Forecasting Model. The results of a sensitivity study with multiple different setups are compared to observations from weather stations and satellite data. We also show the capability of the model to represent extreme snowfall events at different latitudes. This model setup will be used to create both hindcasts and future projections of snowfall across the Andes mountain range, to better understand the implications for changing water resources in the Andes
Extremely long-lived marine heatwave in South China Sea during summer 2020: Combined effects of the seasonal and intraseasonal variations 
Authors: Xu Kang , Han Tongxin , Liu Kai , Wang Weiqiang
Published: March 2024

South China Sea (SCS) experienced an exceptionally long-lived marine heatwave (MHW) event in summer 2020, which broke the historical records in terms of its time duration since 1982. This long-lasting MHW was primarily attributed to the combined effects of the seasonal cycle (SC) and 30-60-day intraseasonal oscillation (ISO) components of anomalous atmospheric circulations. During the SC developing phase, the superimposed anticyclonic circulation regimes of the SC and 30-60-day ISO jointly contributed to the first warming sea surface temperature (SST) peak over the central SCS in July, via the combined effects of net downward shortwave radiation (SWR) and latent heat flux (LHF) anomalies. In contrast, during the SC decaying phase, the SCS MHW-related warming SST tendency was mostly due to 30-60-day ISO signals. During the growth phase of ISO, the joint warming effect of the SWR and LHF anomalies was the dominant factor maintaining the SCS MHW. In the decaying phase of 30-60-day ISO, however, the second MHW-related warming peak around Beibu Gulf in September was mainly contributed by the sharply reduced LHF loss due to strong southwesterly anomalies over the northern SCS on the 30-60-day timescale. The varying SC component play a crucial role in the occurrence and development of MHWs, while the 30-60-day ISO can readily regulate the development of SCS MHWs. These results suggest that, besides the vital role of the SC component, the 30-60-day ISO should also be considered for fully understanding the extreme MHW events.
A criterion for the existence of polar vortices in the Earth’s core
Authors: Majumder Debarshi , Sreenivasan Binod
Published: March 2024

Observations of the Earth’s magnetic field indicate that there are anticyclonic polar vortices in the core. In the presence of the self-generated magnetic field, the polar azimuthal flow is believed to be produced by one or more coherent upwellings within the tangent cylinder, offset from the rotation axis. In this study, convection within the tangent cylinder in rapidly rotating dynamos is understood through the analysis of forced magnetic waves in an unstably stratified fluid. In the dipole-dominated dynamo regime, the isolated upwellings within the tangent cylinder are produced by the localized excitation of slow Magnetic-Archimedean-Coriolis (MAC) waves. If the forcing is so strong as to cause the collapse of the axial dipole, the convection takes the form of an ensemble of plumes supported entirely by fast waves whose frequency is of the same order as that of linear inertial waves. The resulting weak polar circulation is comparable to that in nonmagnetic convection. The observed peak azimuthal motions of 0.6 to 0.9° yr-1 are obtained only in the dipolar dynamo regime, where the Rayleigh number must be of ~103 times the Rayleigh number for the onset of nonmagnetic convection.
How aromatic carbonyls autoxidize in the atmosphere?
Authors: Seal Prasenjit , Barua Shawon , Kumar Avinash , Iyer Siddharth , Rissanen Matti
Published: March 2024

Aromatic carbonyls, emitted either directly in the atmosphere or secondarily formed through hydrocarbon oxidations, represent one of the key members in the family of volatile organic compounds (VOCs). They are common constituents of natural and polluted atmospheres, and their gas-phase oxidation yields highly oxygenated organic molecules (HOM), which are key to the formation of atmospheric aerosol. Although, there are investigations in explaining the autoxidation chemistry of aliphatic carbonyls (Barua et al., 2023; Castañeda et al., 2012, Wang et al., 2015), insights underpinning the molecular level mechanism for the aromatic carbonyl autoxidation, on the other hand, have remained scarce (Iuga et al., 2008). The present work is an attempt to start filling this gap.Herein, we conducted a combined theoretical-experimental analyses in atmospheric conditions for the OH radical initiated autoxidation of aromatic carbonyls, namely, benzaldehyde (PhCHO), acetophenone (PhCOCH3), and phenylethanal (PhCH2CHO). The energetics of the species in the proposed mechanism were obtained using high-level quantum chemical calculations. Subsequently, master equation simulations and multiconformer transition state theory (MC-TST) were used to estimate the rate coefficients and branching ratios for the autoxidation pathways.A nitrate-based time-of-ﬂight chemical ionization mass spectrometer (nitrate-CIMS) was used to detect the products in these oxidation reactions. Chemical ionization was achieved by supplying synthetic air (sheath ﬂow) containing nitric acid (HNO3) under exposure to X-rays. This produces nitrate (NO3−) ions which are mixed with the sample flow and ionizes HOMs as NO3− adducts. The precursors are mixed in a quartz flow tube reactor where the oxidant OH is produced in-situ by the ozonolysis reaction of tetramethylethylene (TME).The study indicates that autoxidation in aromatic carbonyls proceeds via a bicyclic peroxy radical (BPR) intermediate similar to that observed in case of toluene autoxidation (Iyer et al., 2023). The mechanism involves opening of the BPR ring to produce ring-broken intermediates having high excess energy. These nascent intermediates can then lead to several autoxidation pathways resulting in the HOM formation. Our flow reactor measurements for PhCHO oxidation at variable reaction times show the ample formation of HOM monomers and dimers, well in-line with the proposed mechanism.  REFERENCESBarua, S. et al. (2023). Atmos. Chem. Phys., 23, 10517–10532.Castañeda, R. et al. (2012). J. Mex. Chem. Soc., 56, 316–324.Iuga, C. et al. (2008). Chem. Phys. Chem., 9, 1453–1459.Iyer, S. et al. (2023). Nat. Commun., 14, 4984.Wang, S. et al. (2015). Proc. Combust. Inst., 35, 473–480.
Integrating Scientific Insight and Practical Expertise: A High School Initiative on Climate Change
Authors: De Pace Andrea , Da Pra Giuliana , Rusci Rosa , Perron Morena , Navarretta Raffaella , Siciliano Melinda
Published: March 2024

This high school class project involved an impactful collaboration with ARPA Valle d'Aosta (Agenzia Regionale per la Protezione Ambientale – Regional Agency for Environemental Protection).
The project began with an in-depth exploration of various COP conferences. Students partecipated in a dedicated lesson series that dissected the targets, objectives, and outcomes of these conferences, providing them with a nuanced understanding of the global efforts to combat climate change.
With the collaboration of an expert in the field from ARPA, students were engaged into discussion about the prevailing consensus within the scientific community affirming the anthropogenic origins of climate change, the ramifications for our regional glaciers, the imminent threat of permafrost thawing, and the potential ecological repercussions.
Furthermore, the discussion expanded to address the critical issue of climate delay and underlined the importance of collective action over resignation. Students were prompted to contemplate the broader implications of their individual actions, recognizing the importance of a concerted effort in mitigating climate change.
Moreover, students analyzed meteorological models, merging expertise in mathematics (mathematical modeling, statistics), physics (thermodynamics, fluid dynamics), and computer science (numerical data analysis), the goal being to showcase the synergy of diverse disciplines in crafting a precise weather forecast. At the end of the project, students were able to, with some guidance, compile a weather forecast of their own.
This activity has proven useful for students as a guiding tool for their future university choice. 
Deep causal learning for soil water dynamics: Exploring latent causality and improving predictive adaptability
Authors: Wang Lijun , Shi Liangsheng , Song Wenxiang , He Leilei , Wang Yanling , Jiang Shijie
Published: March 2024

Due to its fundamental role in the Earth's hydrological system, understanding and predicting soil water processes has long been important. Rapidly evolving machine learning methods have shown remarkable predictive capabilities, but due to a lack of process understanding, are still insufficient when data is suboptimal or the environment varies. Efforts to integrate prior physical knowledge into learning machines have proven effective in improving the robustness of machine learning models in a complex environment. This improvement has relied heavily on domain-specific knowledge, but the potential for machine learning itself to autonomously understand complex environmental processes, such as soil water movement, is still an intriguing possibility.
To explore this possibility, we have developed a novel causal deep learning method specifically designed to capture the underlying causal mechanism of soil hydrodynamics, thereby enabling the model to adaptively predict vertical profiles of soil moisture in changing environments. By using time-series data from heterogeneous environments, our model is trained to understand the causal interplay between meteorological forcing, environmental factors, and various high-level physical processes that govern the spatiotemporal distribution of soil moisture. The key innovation of our method lies in its ability to use the learned causal relationships as a guide. Even when faced with sparse data in new and untested environments, the model can estimate the differences and adapt its predictions accordingly. Our method is expected to not only enhance soil moisture predictions in new environments, but also provide potentially new insights into a deeper synergy between physical knowledge and data-driven learning.
Croatian strong motion database: ground motion prediction equations tests
Authors: Lončar Iva , Stanko Davor , Markušić Snježana
Published: March 2024

Recent significant seismic events, namely the Zagreb MW5.3 and Petrinja MW6.4 earthquakes in 2020, have highlighted the critical need for enhanced seismic hazard assessment. To facilitate a more accurate assessment of seismic hazard, it is imperative to refine and adjust input parameters. Ground Motion Prediction Equations (GMPEs) assume a pivotal role in this aspect. However, the accurate allocation of GMPEs for specific regions necessitates an extensive database comprising strong motion (SM) recordings. This proves challenging for areas characterized by moderate seismic activity, such as Croatia. In response to this challenge, we have established the first systematic SM digital database, continually updated to address this gap. While the BSHAP database (Salic et al., 2017) was formally recognized as the initial Croatian strong motion database, it primarily contained analogue waveforms, often falling short of satisfactory quality standards. Our database confines its scope to the geographical boundaries of 41.2°N – 47.7°N and 12.5°E – 20.5°E. Comprising over 150 good-quality recordings from 2020 to the present day, with magnitudes equal to or surpassing 3.5, this database serves as a valuable resource. In this study, we tested various widely used Ground Motion Prediction Equations (GMPEs) to define the most suitable models. The findings of this investigation lay the foundation for further GMPE development tailored to the Croatian SM database, leveraging the Hybrid Empirical Method (HEM).  References:Salic, R., Sandikkaya, M.A., Milutinovic, Z. et al. BSHAP project strong ground motion database and selection of suitable ground motion models for the Western Balkan Region. Bull Earthquake Eng 15, 1319–1343 (2017). https://doi.org/10.1007/s10518-016-9950-3
Impacts of an offshore wind farm on biogeochemical fluxes in a seasonally stratified shelf sea
Authors: Williams Charlotte , Wihsgott Juliane , Palmer Matthew , O'Hara Murray Rory , Gallego Alejandro , De Dominicis Michela , Scott Beth
Published: March 2024

The significant expansion of offshore wind farms (OWFs) is a core element of the UK’s decarbonisation strategy. However, in the urgency to meet Net Zero, care must be exercised to avoid exchanging one environmental crisis for another. The PELAgIO (Physics to Ecosystem Level Assessment of Impacts of Offshore Wind) project proposes to inform current and emerging marine policy and management to deliver Net Gain and help achieve Good Environmental Status (GES) using an integrated and co-developed approach to measure, model and understand critical drivers and dependencies of marine ecosystems within a region containing existing and future planned OWFs. Part of the PELAgIO project uses state of the art numerical models combined with observations at the SSE Seagreen wind farm site in a seasonally stratified area of the North Sea (Firth of Forth) to assess the impact of OWFs on water column stratification, mixing and fluxes of nutrients, oxygen and chlorophyll. Observations consisted of a ship-base survey during spring-summer 2023, as well as two gliders which were equipped with sensors to measure temperature, conductivity, turbulence microstructure, dissolved oxygen and chlorophyll fluorescence. Preliminary analysis of the results from the PELAgIO field campaign indicated that the OWF area plays host to significant internal wave activity, evidenced by considerable vertical movement of the thermocline. Additionally the gliders captured an important extreme event in the June 2023 marine heatwave where surface layer temperatures in the Firth of Forth exceeded 16°C, highlighting the need for models to help elucidate natural variability, climate-driven and OWF-driven changes to stratification from one another. Here we show preliminary model and observation results of stratification, nutrient and oxygen fluxes from the Seagreen OWF in the PELAgIO project, and discuss this in terms of impacts to the subsurface chlorophyll maximum. We also outline spatial and temporal gaps in our observations we need to overcome to investigate impacts of OWFs effectively, and discuss how we will attempt to resolve these in the PELAgIO 2024 spring-summer field campaign.
Formation of Standing Whistler Waves in Earth's Magnetosheath
Authors: Wang Yang
Published: March 2024

The dispersion of shock is universal in various media, and in plasmas, standing whistler waves represent the dispersion of collisionless shocks. However, at present, our understanding of the plasma behavior and electric field properties within these waves remains limited. Using conjoint THEMIS and Magnetospheric Multiscale (MMS) observations, we report the first observations of standing whistler waves upstream of fast shocks in Earth’s magnetosheath resulting from the interaction between solar wind tangential discontinuities and the bow shock. High-resolution MMS measurements provide unprecedented insights into these waves, characterizing their circular polarization, near-parallel propagation to the shock normal, and fixed phase relative to the shock ramp. Moreover, generated ion acoustic waves and wave‒particle interactions are observed in these waves. These findings highlight that the magnetosheath is a compelling region for investigating standing whistler wave properties.
Clock Ties: A novel approach for the reduction of systematic errors
Authors: Schreiber Karl Ulrich
Published: March 2024

The techniques of space geodesy, comprising the four techniques, Global Navigation Satellite Systems (GNSS), Very Long Baseline Interferometry (VLBI), Satellite Laser Ranging (SLR) and Doppler Orbitography and Ranging Integrated by Satellite (DORIS) are currently reaching a measurement resolution in the range of 1 part per billion for the terrestrial reference frame. However, a small set of discrepancies remain evident within each of the techniques as well as in the combination of different techniques. Systematic measurement errors are causing this and problems in the local ties between the reference points of the various measurement systems and biases in the atmospheric refraction correction have long been suspected as the main contributors. However, it turns out that errors in the internal delay compensation of the measurement systems are also a significant contributor. They are extremely hard to detect, since they are small and come with different characteristics. It is understood that the experienced delay variation is related to a complex pattern of ambient temperature variation inside of the electronic devices. These changes relate to the micro-climate of the electronic signal path and can both be slow and highly variable. With the advent of high bandwidth mode-locked lasers and active delay compensation in the optical domain, it is now possible to utilize coherent time as an independent probe for instrumental signal delays. The research unit FOR5456 of the German National Science Foundation (DFG) has been formed in 2022 in order to apply and investigate active delay compensation to the techniques of space geodesy. This talk introduces the application of coherent time in space geodesy and its potential to act as a novel tie in fundamental stations.
Post-orogenic radiogenic initiation of intracontinental rifting within the lithospheric mantle
Authors: Maystrenko Yuriy , Slagstad Trond
Published: March 2024

Ocean closure and collisional orogeny frequently enrich the lithospheric mantle in incompatible chemical elements. The most intensive enrichment usually occurs during the subduction of continent-derived sediments and continental crust. Radioactive isotopes of uranium and thorium are part of the HFSE (high-field-strength elements) group of incompatible elements and, therefore, can be also characterized by increased concentration within the post-orogenic lithospheric mantle in comparison to the common lithospheric mantle. The anomalously high content of uranium and thorium within the post-orogenic mantle lithosphere is reflected by the composition of potassic and ultrapotassic magmas, which are sometimes extremely enriched in these radioactive elements. This enrichment is well documented by numerous studies and, therefore, cannot be ignored during the numerical modelling of rifting processes.According to pure conductive thermal modelling, the anomalously increased content of radioactive elements within the post-orogenic lithospheric mantle causes a time-dependent rise in temperature, providing favourable conditions for intracontinental rifting more than 20-100 million years after the closure of the ocean. A time gap between the orogeny and highly increased temperature within the lithosphere is controlled by two major factors: (1) the amount of thorium and uranium and (2) the size of the anomalous lithospheric mantle. According to numerical thermo-mechanic modelling, the post-orogenic increase in temperature not only weakens the lithosphere but also causes thermal expansion of the lithosphere which can be sufficient to initiate the first stage of intracontinental rifting without involving regional extensional forces.Therefore, we propose a new concept of intracontinental rift initiation as a result of time-dependent temperature increase and thermal expansion of the post-orogenic mantle lithosphere due to the decay of radioactive elements. The described rather simple mechanism of rift formation provides a significant advance in our understanding of both local rift processes and global tectonic cycles on our planet.