bluuebunny/crossref_metadata_2025 huggingface dataset:
Decadal trends of the ocean carbon sink in Earth System Models in the past, present and future
Authors: Terhaar Jens
Published: March 2024

The ocean and land biosphere are the two major natural sinks of carbon at present and the ocean is projected to become the dominant sink on centennial timescales when anthropogenic carbon emissions become zero and temperatures stabilize, and. Despite the ocean’s importance for the carbon cycle and climate, uncertainties of the decadal variability of this carbon sink and the underlying drivers of this decadal variability remain uncertain. The main tools to assess the ocean carbon sink over the last decades are global observation-based pCO2 products that extrapolate sparse pCO2 observations in space and time and global ocean biogeochemical models forced with atmospheric reanalysis data. However, these tools (i) are limited in time over the last 3 to 7 decades, which hinders statistical analyses of the drivers, (ii) are all based on the same internal climate state, and (iii) cannot assess the robustness of the drivers in the future, especially when carbon emissions decline or cease entirely. Here, I use an ensemble of 12 Earth System Models (ESMs) from phase 6 of the Coupled Model Intercomparison Project (CMIP6) to understand drivers of decadal trends in the past, present and future ocean carbon sink. The simulations by these ESMs span a period of 251 years and include 4 different future Shared Socioeconomic Pathways, from low emissions and high mitigation to high emissions and low mitigation. Using this ensemble, I show that 80% of decadal trends in the multi-model mean ocean carbon sink can be explained by changes in decadal trends of atmospheric CO2 as long as the ocean carbon sink remains smaller than 4.5 Pg C yr-1. The remaining 20% are due to internal climate variability and ocean heat uptake, which results in a loss of carbon from the ocean. When the carbon sink exceeds 4.5 Pg C yr-1, atmospheric CO2 rises faster, climate change accelerates, and decadal trends in the ocean carbon sink are substantially smaller than estimated based on changes in atmospheric CO2 trends. The breakdown of this relationship under high emission scenarios, also implies that the increase in the ocean carbon sink is effectively limited, even if the trend in atmospheric CO2 continues to increase. This limit of decadal trends in the ocean carbon sink is here estimated to be 1 Pg C yr-1 dec-1.Previously proposed drivers, such as the atmospheric CO2 or the growth rate of atmospheric CO2 can explain trends in the ocean carbon sink for specific time periods, for example during exponential atmospheric CO2 growth, but fail when emissions start to decrease again. The robust relationship over a large Earth System Model ensemble also suggests that very large  positive and negative decadal trends of the ocean carbon sink by some pCO2 products are highly unlikely, and that the change in the decadal trends of the ocean carbon sink in 2000 is likely substantially smaller than estimated by these pCO2 products.
Evaluating heat extremes in the Sahel using ESA-CCI Land Surface Temperature data
Authors: Maroini Amina , Albergel Clement
Published: March 2024

Heatwaves are becoming more intense, occurring more frequently, and lasting longer, and they do not spare the Sahel, a region characterized by a hot and semi-arid climate and projected to be particularly vulnerable to heatwaves. Since there is a clear lack of long-term in-situ data to study past and climate trends of climate extremes in this region, Essential Climate Variables - i.e. long term, global scale, robust time series of key component of the climate system -  derived from satellite data could provide a unique opportunity to study such trends. Therefore, we use ESA-Climate Change Initiative’s (ESA-CCI) Land surface Temperature (LST) to evaluate the performance of satellite data in capturing the spatial and temporal characteristics of historical extreme heat events in the Sahel region. Through the computation of a range of monthly indices measuring the intensity, duration, and human perception of extreme heat, we compare the results obtained from LST-CCI All Microwave products during a reported severe heatwave with those from ERA5 reanalysis and observational gridded products.  Additionally, we investigate the potential of current and future high-resolution Earth Observation derived data products in enhancing the monitoring of extreme heat events.
Seawater intrusion in coastal agricultural regions: a global review
Authors: Ghiardelli Aurora , Straffelini Eugenio , Park Edward , D'Agostino Vincenzo , Masin Roberta , Tarolli Paolo
Published: March 2024

Coastal agriculture is key in sustaining food production for the growing global population. Due to highly fertile soils and water availability, lowlands located in the proximity of river mouths often represent the backbone of coastal agricultural activities. However, over the past decades, anthropogenic-related processes are reducing yield increases. Climate change has rapidly become a major threat, with sea-level rise (SLR) and extreme weather events such as prolonged droughts and record-breaking temperatures. In addition, deltaic areas are often densely populated, and intense human activities undermine the resilience of coastal agro-environments. In this context, seawater intrusion (SWI) is one of the most damaging processes affecting agriculture through soil salinization and the depletion of irrigation water resources. This leads to crop damage, huge yield losses and permanent harm to soil fertility. Despite the relevance of the topic worldwide, to this date, there is a lack of global synthesis on the impact of SWI on coastal agriculture and an insufficient consideration of the phenomenon in local surveys. To fill this research gap, we present a systematic review of the global distribution and impact of SWI in coastal agriculture of river deltas, focusing on the main hotspots and prevalent drivers, related to climate change, natural processes, and local human activities such as dam construction, dredging or groundwater overexploitation. Moreover, the global study helps to highlight the areas where data is insufficient and compares patterns of SWI across different regions. Additionally, the study assesses the global distribution of rural regions potentially impacted by SWI and the main crops characterizing the economies of river deltas. Finally, we delve into the future implications of demographic growth and SLR projections in deltaic regions, discussing the possible scenarios of coastal agriculture regarding water management, agronomic practices, and relative sustainability.
Cloud-based agricultural crop water use monitoring across Saudi Arabia
Authors: Lopez Valencia Oliver Miguel , Li Ting , Aragon Solorio Bruno Jose Luis , McCabe Matthew Francis
Published: March 2024

Monitoring agricultural water use is essential to ensure water security, especially in regions facing water scarcity. Satellite-acquired multi-spectral images of the Earth’s surface provide crucial data to enable frequent estimations of crop water use. In large data-scarce regions, these estimations represent a key source of information for water management. The emergence of cloud-based platforms, such as Google Earth Engine (GEE), has made it feasible, accessible, and cost-effective to automate crop water use monitoring pipelines. Here, we demonstrate the potential benefits of a cloud-based crop water use estimation and monitoring framework by estimating a decade's worth of agricultural water use over Saudi Arabia. In Saudi Arabia, large-scale agricultural activities account for the majority  (>80%) of water use, water which is sourced primarily from non-renewable groundwater resources from the Arabian Shelf. Saudi Arabia’s large land area (> 2 million  km2) and the long study period (+10 years) forms the basis of a case-study for our cloud-based model. Previous mapping efforts provided annual maps of individual field boundary delineations at, identifying more than 30,000 fields covering a total of more than 10,000 km2 of croplands that are distributed across several large-scale agricultural clusters within the Kingdom. As a preprocessing step, we developed an approach to generate large-scale delineations of irrigated agricultural regions over arid areas. This approach helped reduce processing efforts for field delineations, and at the same time reducing the water use estimation computations. Our GEE cloud-based model implements a two-source energy balance model (TSEB) and automatically incorporates all available Landsat collection 2 surface reflectance and surface temperature products from Landsat 7, 8, and 9, along with climate reanalysis data from the ECMWF ERA5-Land hourly product. The model can be readily applied elsewhere by defining just the date range and study geometry, while allowing the flexibility for more advanced users to control parameters within the TSEB model. Total crop water use (evapotranspiration term only; not accounting for irrigation efficiency) was estimated at between 7 and 12 BCM per year of study, with the highest use in 2016 and the lowest in 2020. Both Riyadh and al Jawf administrative regions collectively shared more than half of the total study cropland area, and a similar contribution of water use. This study represents the convergence of a number of efforts towards developing operational crop water use monitoring, while motivating further applications in other regions and providing a rich dataset for further food and water security related studies.
Introducing the ’miniRECgap’ package with GUI-supported R-scripts for simple gap-filling of Eddy Covariance CO2 flux data
Authors: Premrov Alina , Yeluripati Jagadeesh , Saunders Matthew
Published: March 2024

The Eddy covariance (EC) is a well-known technique used (among others) to investigate the ecosystem exchange of greenhouse gasses (GHGs) between the biosphere and the atmosphere (Burba et al., 2007), often required in studies on soil-plant-atmosphere interactions and GHG emissions/removals from different soil systems. The long data records from EC measurements often experience data gaps due to various reasons (BaldocchiI, 2003) resulting in  many gap-filling methods being developed over the past decades. This study is introducing the new ’miniRECgap’ (Premrov, 2024) computational tool, which is using so-called ‘classic’, traditional robust and validated modelling approaches for gap-filling the missing EC CO2 flux measurements,  based on the application of environmental temperature and light response functions (Lloyd and Taylor, 1994; Rabinowitch, 1951) in combination with empirical/semi-empirical parameter-optimisation. ‘miniRECgap’ is a very small R package that operates in a user-friendly way via GUI (Graphical User Interface) supported scripts. It is purposely designed to be simple, operating in only 5 steps. The application of ‘miniRECgap’ will be demonstrated using EC CO2 flux data from an Irish peatland site Clara Bog. Due to its simplicity, it is thought that the new tool may be beneficial for new R users and that it may allow for easier and less time-consuming testing of the potential suitability of ‘classic’ empirical/semi-empirical gap-filling on different datasets. AcknowledgementsThe authors are grateful to the Irish Environmental Protection Agency (EPA) for funding the CO2PEAT project (2022-CE-1100) under the EPA Research Programme 2021-2030. ReferencesBaldocchiI, D.D. (2003) Assessing the eddy covariance technique for evaluating carbon dioxide exchange rates of ecosystems: past, present and future.  9, 479-492.Burba, G., Anderson, D., Amen, J., (2007) Eddy Covariance Method: Overview of General Guidelines and Conventional Workflow, AGU Fall Meeting Abstracts, pp. B33D-1575.Lloyd, J., Taylor, J.A. (1994) On the temperature dependence of soil respiration. Functional Ecology 8, 315-323.Premrov, A., (2024) miniRECgap. R package  with GUI suported scripts for gap-filling the of Eddy Covariance CO2 flux data.  Copyright: Trinity College Dublin. URL:  'miniRECgap package will be uploaded on GitHub in near future'.Rabinowitch, E.I. (1951) Photosynthesis and Related Processes. Interscience Publishers.
Artificial intelligence for country-scale land cover description.
Authors: Garioud Anatol
Published: March 2024

The National Institute of Geographic and Forest Information (IGN) has developed Artificial Intelligence (AI) models that describe land cover at the pixel level from IGN aerial images. This is part of the production process for the Large Scale and Land Use Reference (OCS GE). This contribution is threefold:Methodology: the training strategy and the use of these models will be reviewed by focusing on i) the selection of the task performed by the models, ii) the approach for choosing and producing learning samples and iii) the training strategy to generalize to the scale of Metropolitan France. The evaluation of the models using various metrics will also be discussed. Visuals will be provided to illustrate the quality of the results. Furthermore, we will explain how AI products are incorporated into the production of the OCS GE.Continuous improvement: the models are continuously improved, particularly through the implementation of FLAIR (French Land cover from Aerospace ImageRy) challenges towards the scientific community. The challenges FLAIR#1 and FLAIR#2 dealt with model generalization and domain adaptation as well as data fusion, i.e., how to develop an AI model that can process very high spatial resolution images (e.g., IGN aerial acquisitions) and satellite image time series (Sentinel-2 images) as input. We will both review the challenges implementation and the obtained results, leveraging convolutional and attention-based models, ensembling methods and pseudo-labelling. As the AI model for land cover goes far beyond the context of OCS GE production, additional experiments outside of the challenges will be discussed, allowing the development of additional AI models to process other modalities (very high spatial resolution satellite images, historical images, etc.).Open access: all source code and data, including AI land cover predictions maps, are openly distributed. These resources are distributed via the challenges and as products (CoSIA: Land Cover by Artificial Intelligence) by a dedicated platform, which is of interest for AI users and non-specialists including users from the geoscience and remote sensing community.
Assessment of NO2 and PM2.5 exposure with air quality sensors
Authors: Chacon-Mateos Miriam , Remy Erika , Liebers Uta , Witt Christian , Heimann Frank , Vogt Ulrich
Published: March 2024

According to the World Health Organization, poor air quality contributes heavily to the Global Burden of Disease, causing more than 6.7 million deaths each year due to both ambient air pollution and household air pollution. With advances in air pollution monitoring technology, evidence on the adverse health effects of air pollution has been increasing. Still, the understanding of personal exposure is limited by the low spatial resolution of fixed outdoor monitoring stations. Low-cost sensors have the potential to enhance personal exposure prediction at scales required for population-based research.In this study, we carried out a pilot project to evaluate the feasibility of using low-cost sensors at fixed-locations for epidemiological investigations. Stationary sensor systems for NO2 and PM2.5 were custom-built and deployed both in- and outside the homes of individuals diagnosed with asthma or chronic obstructive pulmonary disease (COPD). Measurements were taken for approximately 30 days at each participant’s home. The study was designed to evaluate the performance of the air quality sensors over a longer timeframe, which so far has not been thoroughly studied (Sesé et al. 2023). Participants self-reported symptom data to study the relationship between indoor air quality and health. Participants recorded their daily activities as well, as part of examining the exposure estimates and indoor pollutant sources. To evaluate the exposure misclassification, the potential dose was calculated using the data of an outdoor monitoring station and the indoor sensors, as well as the generic and the activity-specific inhalation rate. Steps completed prior to this analysis include a study on a low-cost dryer for the PM sensor to prevent the overestimation of the mass concentration due to the hygroscopic growth of particles (Chacón-Mateos et al. 2022), and processing of the NO2 data using machine learning to evaluate the uncertainty, reproducibility, reliability, and sensitivity of the sensors. The results of this work highlight the importance of monitoring indoor air quality and activity patterns to avoid exposure misclassification. With the appropriate methodology and a robust calibration, air quality sensors can provide us with useful information and show promise for epidemiological investigations.References:Sesé, L.; Gille, T.; Pau, G.; Dessimond, B.; Uzunhan, Y.; Bouvry, D. et al. (2023): Low-cost air quality portable sensors and their potential use in respiratory health. In Int. J. Tuberc. Lung Dis. 27 (11), pp. 803–809. DOI: 10.5588/ijtld.23.0197.Chacón-Mateos, Miriam; Laquai, Bernd; Vogt, Ulrich; Stubenrauch, Cosima (2022): Evaluation of a low-cost dryer for a low-cost optical particle counter. In Atmos. Meas. Tech. 15 (24), pp. 7395–7410. DOI: 10.5194/amt-15-7395-2022
Spontaneous Hot Flow Anomalies at Earth’s foreshock.
Authors: Blanco-Cano Xochitl , Rojas-Castillo Diana , Kajdic Primoz
Published: March 2024

In recent years we have learnt that foreshock transients play an influential role in solar wind coupling with Earth’s magnetosphere. These transients include Spontaneous Hot Flow Anomalies (SHFAs) which are characterized by dips in magnetic field magnitude and ion density, enhanced temperature, and are surrounded by ultra low frequency waves. SHFAs share some characteristics with hot flow anomalies but their formation mechanism does not require a discontinuity in the solar wind.  SHFAs evolve from caviton interaction with backstreaming ions. We use Cluster and MMS magnetic field and plasma data to study SHFAs internal structure and their evolution. We find that SHFA can occur not only deep in the foreshock as initially thought, but they can also been observed near the foreshock boundary where higher frequency waves (f ∼ 1 Hz) exist. We also investigate the properties of velocity distribution functions inside these transients, and their influence on bow shock structure.
A lower crust shear zone favors delamination and continental subduction in the Apennines
Authors: Menichelli Irene , Bianchi Irene , Chiarabba Claudio
Published: March 2024

Understanding the physical characteristics and structure of the lithosphere is crucial in unraveling the evolution of mountain belts. In this study, we present detailed Vs profiles of the Apennine lithosphere that shed light on a controversial aspect of continental subduction: the intricate process of crustal delamination from the descending plate. Through an accurate analysis of a dense teleseismic Receiver function data set (comprising over 15,000 teleseismic events), we find that the delamination of continental lithosphere is facilitated by the development of a low Vs shear weak zone within the mid-lower crust.Utilizing a Reversible-jump Markov chain Monte Carlo (RjMcMC) approach for computing 1D Vs models across the central Apennines, we mitigate the reliance on a-priori information, thus enhancing the robustness of the final solution.We observe a double Moho beneath the outer regions of the current mountain range, indicating the gradual development of a shallow interface. This incipient formation of the double Moho finds a mature-stage equivalent in the backarc, where crustal thinning and magmatism ensued following the re-establishment of the shallow Tyrrhenian Moho.Proposing a novel scenario for Apennine subduction, we hypothesize that the onset of delamination occurs in the forearc, necessitating a longer thermal rebalancing. This hypothesis suggests that sustained continental subduction can persist if it develops at mid-lower crustal depths within weak rheology inhibiting the slab break-off process.Our findings present a new perspective on continental subduction and offer prognostic insights into the long-term evolution of the Apennines over the next 7-10 million years.
The rapid increase in ice thickness along Nares Strait following ice arch formation
Authors: Moore Kent , Howell Steve , Ballinger Thomas , McNeil Kaitlin , Brady Mike
Published: March 2024

Nares Strait, situated between northwest Greenland and Ellesmere Island, is an important conduit for the export of sea ice from the Arctic, including thick multi-year ice that is undergoing an accelerated loss.  This export is modulated by the presence of ice arches that can form along the strait, and that can remain stable for months at a time.  When an arch is present, there is no export of sea ice along the Strait.  The formation and stability of ice arches is a function of sea ice thickness. There is a concern that the observed thinning of Arctic sea ice may be weakening the arches, resulting in an accelerated loss of sea ice from the Arctic. However, little is known about sea ice thickness's spatial and temporal variability along the Strait.  Here we show that after an arch forms, ice motion continues north of the arch for a period of time that results in a rapid dynamical thickening of the sea ice in the vicinity of the arch. Over the period of a month after arch formation, the ice thickness may increase by up to 1.0m.     This dynamically driven increase in sea ice thickness may help explain why the arches remain stable once they form.
Seasonal movement behavior of goats related to grazing intensity and environmental variability using Hidden Markov Models
Authors: Cheng Hua , Johansen Kasper , Jin Baocheng , McCabe Matthew Francis
Published: March 2024

Key research in movement ecology is investigating shifts in animal behavior and identifying the factors that induce alterations in movement behavior and mechanics. The impact of natural environments and human activities on the underlying behavioral processes of domestic goats are still being elucidated. We applied seasonal multivariate Hidden Markov Models (HMMs) to characterize the fine-scale movements (30- second intervals) of GPS-tracked Zhongwei goats for 124 days and determine how grazing intensity, seasonal food resources, terrain factors and daylight hours affect movement behavior in the mountain grassland in China. We classified the goats’ activities as two basic behavioral states of foraging (low step length, varied and undirected turning angle) and travelling (long step lengths, low and directed turning angles). Grazing intensity, a management factor, exerted the most significant influence on goats across different seasons. Additionally, factors such as daylight hour and slope had a more pronounced impact on their movement activities compared to the normalized difference vegetation index (NDVI). Elevation and solar radiation were found not explain much of the variability in movement behavior of goats. Their probability of foraging behavior was most likely to increase with grazing intensity, slope, diurnal hours and NDVI. In addition, the percentage time allocation of foraging was higher in spring and winter with lower food resources periods and shorten daylight hours, than summer and autumn with larger food resources and long daylight hours. The foraging percentage increased from morning to afternoon. HMMs are found useful for disentangling movement behavior and understanding how goats respond to seasonal grazing intensity, time of daylight, NDVI and slope. Our findings underscore the importance of accounting for interactions between movement behavior and gazing management, not only the environmental factors and behavioral rhythms, when assessing the movement characteristics and behavioral transitions of goats. These results are important for designing grazing management strategies that satisfy ecological and socioeconomic demands on mountain grassland ecosystems.
Sources of PM2.5- and ozone-related health impacts in Europe and their response to emission changes
Authors: Gu Yixuan , Henze Daven , Nawaz M. Omar , Wagner Ulrich
Published: March 2024

The deterioration of air quality is a global concern, contributing to millions of premature deaths annually worldwide. In Europe alone, hundreds of thousands of lives are cut short every year due to the effects of air pollution. This alarming reality underscores the need to comprehensively understand the cause of regional air pollution and find cost-effective solutions to mitigate the consequences of air pollution on public health. We have recently established an improved decision support tool to characterize high-resolution sensitivity of PM2.5- and ozone-related health impacts to different species emissions in Europe by incorporating the satellite-derived surface PM2.5 concentration products into the GEOS-Chem adjoint model. In 2015, the total PM2.5- and ozone-related premature deaths are estimated to be 449,813 (257,846–722,138) and 25,432 (7,356–53,160), respectively. The anthropogenic emissions of nitrogen oxides (NOx), ammonia, and organic carbon contributed most to the PM2.5-related health damages, making up 29.6%, 23.2%, and 16.8%, respectively of all domestic anthropogenic contributions. Residential, agricultural, and ground transport emissions are calculated to be the largest sectoral sources of PM2.5-related health risks, accounting for 23.5%, 23.0%, and 19.4%, respectively, of total anthropogenic contributions within Europe. The ozone-related health impacts are mostly associated with the contributions from NOx emissions. A 20% decrease in anthropogenic emissions can help to avoid 1576 (467–3,252) premature deaths from respiratory diseases. Within these benefits, contributions from emissions of NOx, volatile organic compounds (VOCs), and CO help to avoid 1105 (328–2,300), 381 (113–770), and 99 (29–200) premature deaths, respectively. During 2005–2015, emission controls reduced PM2.5-related health damages in nearly all European countries, resulting in 63,538 (46,092–91,082) fewer PM2.5-related premature deaths. However, our calculation suggests that efforts to reduce air pollution from key sectors in some countries can be offset by the lack of emissions control in others. The emission changes also lead to general increases in the marginal ozone-related health benefit per unit of NOx emission reduction. Increasing marginal health benefits imply that more costly regulations of NOx emissions are economically justified even as total anthropogenic emission are declining. International cooperation will thus be important for effectively tackling air pollution and reducing corresponding detrimental effects on public health in Europe.
Geotechnical Investigation and stability analysis of River Bank retreat along the Critical Reaches of Brahmani River, Odisha, India
Authors: Anand Aditya Kumar , Pradhan Sarada Prasad
Published: March 2024

River embankment breaches across the critical reaches of the Brahmani River, causing vulnerability of livelihood, agricultural land, and loss of livestock. Planform and slope-forming parameters are implemented to decipher the critical zones of avulsion along the Brahmani River. River bank retreats along very high to high moderate zones of insitu migration have been monitored along the middle and lower reaches of Brahmani River, Odisha. The uncertainties in predicting bank failure mechanisms result from a lack of detailed observations of a bank collapse. The soil samples are collected for laboratory investigation to decipher the geotechnical properties of soil samples. Sieve analysis, proctor compaction test, atterberg limits and soil triaxial test are performed to determine grain size, moisture content, density, cohesion and angle of internal friction. The saturated/Unsaturated flow of river bank slopes using finite element method has been simulated using fully coupled flow deformation analysis in Plaxis 2D. The river bank stability analysis has been monitored with river water level fluctuation data from 2000-2013 for a better understanding of factors influencing bank changes and various processes of seasonal scale. Seven major flood events occurred from 2000 to 2013, with the highest discharge of 12000 cumecs recorded during peak flood events. Bank simulations are performed by linking river water level, precipitation, discharge and groundwater flow of flood events. The simulation of river bank failure allows identification of (i) probable zones of failure of the slopes, (ii) effects of slow and rapid draw down on stability mechanism, and (iii) role of discharge, precipitation and river water level fluctuation in factor of safety. The result of river bank simulations represents the bank erosion process and its relative dominance according to the seasonal hydrological cycle and bank geometry.
Relative role of land and ocean in shaping tropical hydroclimate after large volcanic eruptions
Authors: Timmreck Claudia , D'Agostino Roberta , Fang Shih-Wei , Ballinger Andrew , Hegerl Gabriele , Kang Sarah , Olonscheck Dirk , Schurer Andrew
Published: March 2024

Volcanic eruptions substantially impact tropical precipitation over the historical period but they differ in their emission strength, geographical latitude and season of the eruption, which makes it difficult to draw general conclusions. Sufficient large ensembles simulations with the same model and radiative forcing scenario but varying initial conditions have become a great tool in recent years to disentangle forced and internal variability).  Here we use a suite of 100-member ensembles of the MPI-ESM-LR for idealized equatorial and extratropical eruptions of different eruption strengths and an additional 100-member ensemble without forcing. We find that precipitation reduction is primarily energetically constrained by less atmospheric net energy input (NEI).  NEI decreases rapidly in the first months after the eruption due to reduced incoming solar radiation and then the circulation weaken as a consequence of less moist static energy (MSE) exported away from the intertropical convergence zone. Only afterwards, when the overturning has already weakened, the MSE, and then the gross moist stability (GMS) contribute stronger to the precipitation reduction. Tropical precipitation over land reacts immediately to forcing changes, while the precipitation response over the ocean and the temperature response have much longer response times. Altered dry-wet pattern (“wet gets drier”) and the decreased monsoon precipitation are strongly tied to the weakening of the regional tropical overturning. Differences related to the geographical locations of the volcanic eruptions will be highlighted.
PHEBUS observations of exospheric calcium and potential detection of exospheric manganese during BepiColombo first three flybys of Mercury.
Authors: Robidel Rozenn , Quemerais Eric , Chaufray Jean-Yves , Leblanc Francois , Koutroumpa Dimitra
Published: March 2024

BepiColombo, the ESA/JAXA joint mission, has already performed three out of the six flybys of Mercury scheduled during its journey to the innermost planet of our solar system. The first two flybys were conducted at a similar True Anomaly Angle (TAA~265°), while the third one occurred closer to the perihelion (TAA=311°).During these three flybys, several instruments observed the planet and its environment, including PHEBUS (Probing of Hermean Exosphere By Ultraviolet Spectroscopy), the UV spectrograph on board BepiColombo/MPO. The two visible channels of PHEBUS, centered at 404nm and 422nm, observed Mercury’s exosphere during each of the three flybys. The third flyby provided the first observations of the southern hemisphere of Mercury. Indeed, PHEBUS was pointing towards the south ecliptic direction during the third flyby while the instrument was pointing towards the north ecliptic direction during the first two flybys.We report the detection of the calcium (Ca) emission line at 422.8nm during each of the three flybys. Our results reveal that Mercury Ca exosphere is very extended on the morning side (up to ~10,000 km of altitude) and is enhanced near the dawn region. We then discuss year-to-year variability and potential source processes.We also report the detection of additional species with the visible channel centered at 404nm during the three flybys, potentially manganese (Mn) or potassium (K). The detection is confined to the predawn region. Mn was detected by MESSENGER at similar local times (2-5 A.M.) but at different TAA (0-70°). However, the K doublet near 404nm has never been detected by MESSENGER.Finally, we briefly discuss the geometric configuration of the next flybys of Mercury that will take place in September 2024, December 2024 and January 2025.
Mid-mantle imaging through a reverberant transition zone: A CRISP-RF approach
Authors: Carr Steve , Olugboji Tolulope
Published: March 2024

On a planet that dissipates heat through whole mantle convection, no sharp changes in elastic properties are expected in the mid-mantle: ~750-1300 km. Yet, a growing number of seismic studies continue to document evidence of discontinuities across these depths. Compared to the upper mantle, the global prevalence and causal origins of such features remain relatively enigmatic. Here, we investigate mid-mantle layering beneath two large seismic arrays (US and Alaska) using high-resolution Ps-converted waves. The challenge is that top-side reflections (reverberations) from the mantle transition zone interfere with and contaminate desired mid-mantle conversions and make their interpretation difficult. In the past, the slowness slant stack (vespagram) approach has been used. We extend the resolution of this stacking scheme using a newly developed sparsity-promoting, non-linear, CRISP-RF technique (Clean Receiver function Imaging with Sparse Radon Filters). Preliminary results suggest that CRISP-RF can isolate high-frequency (0.5Hz) mid-mantle body wave conversions buried within transition zone reverberations. With our filtered Ps-RFs and machine learning, we will present tighter constraints on mid-mantle layering (depth, sharpness, spatial variation)  exploring important implications for its origin.  
Meta-analyzing geological data for seismic hazard assessment: the case study of central Apennines
Authors: Di Naccio Deborah , Di Lorenzo Cinzia , Battistelli Marco , Miccolis Simona , Kastelic Vanja , Carafa Michele MC
Published: March 2024

In the past decade, seismic hazard assessment has progressively relied on innovative approaches based on seismotectonic models for robust physical-based short-term and long-term estimations. For this reason, consistency and homogenization are crucial in collecting data for a scientifically sounding seismotectonic model, especially when dealing with large amounts of information at different temporal and spatial scales. Additionally, a solid probabilistic approach is needed to correctly explore the uncertainties of the seismotectonic model components (e.g., offset, age, long-term slip rate). In this contribution, we focus on the active tectonics of the central Apennines because they have been repeatedly investigated in past decades, and a significant amount of complementary data is available. In such a case, we can define an innovative fault database for seismic hazard assessment, exploring in a probabilistic sense the deformation data (age and offset) and rate (long-term slip rate). Our approach provides a substantial methodological upgrade to fault-based input for seismic hazard assessment. The proposed methodology can be easily exported to zones with scarce data availability.
Ionospheric Conductance Derived from Satellite Measurments: Limitations and Implications
Authors: Pourkarim Pouya , Knudsen David
Published: March 2024

Ionospheric Pedersen conductance ∑P can be remotely measured using electric and perturbation magnetic fields measured above the high – latitude ionosphere, subject to assumptions of sheet – like current systems, quasi – static electric and magnetic fields, neglect of magnetic perturbations generated by Hall currents, and locally constant ∑P (Sugiura et al., 1982). Using Swarm measurements, we see large variability and lower – than expected magnitudes at small scales, and dawn – dusk asymmetries in large scales of ∑P upon comparison with existing models and results. To rectify the observed discrepancies, we revisit the underlying assumptions, provide root – cause analysis, and discuss the implications.
Proposal for a Geoethics Code for the Geoscientist Community of Chile
Authors: Bobadilla Hernán , Pinto Lincoñir Luisa , Ramirez Pablo , González Thiare , Benado José , Lay Nilda , Villaseñor Tania , Valenzuela Millarca , Alam Mohammad Ayaz , Pérez Alejandro
Published: March 2024

The proposal of the Geoethics Code (hereinafter “Code”) of the Geological Society of Chile arises as a strategic objective of the Geoethics Group within this institution. The Code encapsulates the principles and values that ethically guide and protect the professional decisions of geoscientists in Chile to protect society and the environment. Likewise, it establishes standards of conduct from the personal to the environmental dimension of professional and scientific practice. Consequently, the Code serves as a valuable tool to the geoscientist community in Chile, facilitating reflection and decision-making within an ethical framework.Grounded in the principles and values defined by the Geoethics Group of the Geological Society of Chile and the Cape Town Geoethics Declaration of the International Association Promoting Geoethics (IAPG) from 2016 (Di Capua et al., 2017), the Code is built upon four titles: a) Professional and scientific work; b) Geosciences and its relationship with society; c) Geosciences and its relationship with the environment; and d) Contribution to new generations of scientists and professionals in Geosciences.The construction strategy of the Code underscores the pivotal role of the Chilean geoscientist community. Thus, the Code proposal was enriched through consultations, including surveys, meetings, discussions, and seminars, engaging the Geoscientist Community of Chile to understand their perspectives on pertinent topics and challenges. Furthermore, consultations and reflections were conducted to validate the Code proposal before and during the XVI Chilean Geological Congress in 2023. Ultimately, the Code underwent validation with experts from the IAPG, including geoscientists representing Latin America. Consequently, the Code authentically represents the concerns and challenges of the national geoscientific community while also resonating with the international geoscientific community.FinancingThis project is sponsored by the Geological Society of Chile.AcknowledgementsTo the geoscientist community of Chile, the IAPG experts and other professionals who have participated in the process of construction and reflection on the titles of the proposed Geoethics Code.ReferencesDi Capua, G., Peppoloni, S., Bobrowsky, P.T., 2017. The Cape Town Statement on Geoethics. Annals of Geophysics, 60, Fast Track 7: Geoethics at the heart of all geoscience. doi: 10.4401/ag-7553.KeywordsGeoethics Code, Principles and Values, IAPG, Geoscientist Community.
Vegetation and Climate Patterns of Western Türkiye since the Late Glacial Period Based on Pollen Records in the Aegean Sea
Authors: Kolbüken Mesut , Biltekin Demet , Aksu Ali Engin , Hiscott Richard , Arıkan Bülent , Yakupoğlu Nurettin
Published: March 2024

Pollen analysis of the MAR03-02 core from the Aegean Sea (38°03.97'N, 26°22.30'E), western Türkiye allows us to reconstruct paleo-vegetation patterns and paleo-climate dynamics of the surrounding territory since the Late Glacial Period. We present palynological record from the topmost 2.8 m of a sediment core (MAR03-02) collected in the Aegean Sea, covering the last 20.7 ka. Variation in Mediterranean/temperate forests and herb/step plants indicates major climatic shifts connected to Heinrich Stadial 1, Bølling-Allerød, Younger Dryas, and the Holocene Climatic Optimum as well as some Rapid Climate Changes such as the 9.4, 8.2 and 5.9 ka events, Medieval Warm Period and Little Ice Age during the Holocene. In the cold and dry periods, low Arboreal Pollen (AP) and high amounts of herbaceous and steppe plants, including Artemisia, Cyperaceae, and Asteraceae Chichorioideae were recorded.  In warmer periods, high AP which was mainly characterized by deciduous Quercus, and low herbaceous/steppe plants dominated in the region. A warm-temperate and Mediterranean trees, consisted of mainly deciduous Quercus and Quercus ilex-type, reached the maximum level from the onset of the Holocene to 6 ka, which corresponded to the Holocene Climate Optimum. The pollen records show similarities with regional proxy records. Anthropogenic impacts occurred clearly during the last 2 ka when cultivated plants become prominent in the pollen records (e.g. Olea europea and Pistacia).
The Europa Clipper Flight System on its Path to Launch 
Authors: Korth Haje , Pappalardo Robert , Buratti Bonnie ,   Europa Clipper Flight System Engineering Team
Published: March 2024

At the beginning of the next decade, the Europa Clipper Flight System will enter orbit around Jupiter and, over a four-year period, will fly by Europa nearly 50 times to explore the habitability of this planet’s moon Europa. The Flight System comprises (1) the Propulsion Module, which provides the thermally-controlled spacecraft structure, propulsion subsystem, and solar array; (2) the Avionics Module, which enables spacecraft guidance, navigation, and control operations, provides power conditioning and computer resources which stores and prioritizes science data for downlink; (3) the Radio-Frequency Module, which provides telemetry uplink and science data downlink capabilities; and (4) a highly capable suite of remote-sensing and in-situ instruments to achieve the science objectives of the mission. The remote sensing payload consists of the Europa Ultraviolet Spectrograph (Europa-UVS), the Europa Imaging System (EIS), the Mapping Imaging Spectrometer for Europa (MISE), the Europa Thermal Imaging System (E-THEMIS), and the Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON). The in-situ instruments comprise the Europa Clipper Magnetometer (ECM), the Plasma Instrument for Magnetic Sounding (PIMS), the SUrface Dust Analyzer (SUDA), and the MAss Spectrometer for Planetary Exploration (MASPEX). Gravity and radio science will be achieved using the spacecraft's telecommunication system, and valuable scientific data will be acquired by the spacecraft’s radiation monitoring system. The mission is presently in the assembly, testing, and launch operations (ATLO) phase. The Propulsion and RF Modules have been delivered from the Johns Hopkins Applied Physics Laboratory (APL) to the Jet Propulsion Laboratory (JPL). The flight system integration and environmental testing has been completed at the Jet Propulsion Laboratory. The flight system is presently undergoing a series of operations tests. In May 2024, it will be shipped to Kennedy Space Center, where it will be integrated with the solar array, which was delivered to the location earlier this year. The launch period begins on 10 October 2024, and once lifted off, the Europa Clipper will be cruising to the Jupiter System with gravity assists by Mars followed by Earth on the way. Go Europa Clipper!
Critical transition in barrier island’s state and the loss of barrier resiliency
Authors: Ramakrishnan Kiran Adhithya , Rinaldo Tobia , Duran Vinent Orencio
Published: March 2024

Barrier islands cover a large portion of US coasts, support unique ecosystems and beach communities, and protect inland infrastructure from direct storm impacts. Based on their elevation, they can exist in three possible states: relatively protected “high-elevation” barriers with well-developed coastal dunes, vulnerable “low-elevation” barriers without dunes, and “mixed” barriers with scattered dunes separated by overwash fans. We analyzed data from 16 barriers along US coasts and found that the island state is controlled by the barrier ‘elevation capital’, loosely defined as the elevation of the barrier excluding dunes. We find a critical value of the elevation capital, around 0.5m, below which eroded dunes cannot recover and the barrier remains low-elevation, a value consistent with predictions from a recent analytical model of the barrier’s stochastic dynamics. Under the current sand supply, we find that several barriers already reached the tipping point for a potentially permanent “low-elevation” state. We predict this transition to become widespread under expected trends in sea level rise, with important implications for the survival of the whole barrier system.
Frequency Response Evaluation of a Low-power Closed-path Eddy Covariance System for Measuring Nitrous Oxide Fluxes
Authors: Bogoev Ivan
Published: March 2024

The eddy covariance (EC) method has been widely used to capture the temporal and spatial patterns of nitrous oxide (N2O) emissions from a wide variety of agricultural ecosystems. Technological advancements in the recent years have brought new tunable infrared laser-based closed-path gas analyzers suitable for EC measurements. To achieve high sensitivity and low measurement noise, these analyzers use multi-pass optical cells with long sensing path. A drawback of these cells is the relatively large internal volume requiring high-flow rate, high-power pumps to attain fast response to changes in gas concentration.  Additionally, these cells are prone to contamination and require in-line filters. In this study we evaluate the frequency response of a novel, low-power, field deployable N2O closed-path EC system consisting of: (1) a gas analyzer with a small volume single-pass optical cell, (2) a 3 m sulfonated tetrafluoroethylene ionomer intake tube acting as water vapor permeable membrane to dry the air sample, (3) a cyclone type, non-barrier inertial particle separator (IPS) to mitigate the effects of particulates contamination of the optical sample cell, and (4) a small, low-power pump module with an automatic pressure and flow control. The performance of the new N2O EC system is evaluated in-situ 3 m above a fertilized agricultural wheat field and compared to a co-located fast-response H2O and CO2 open-path gas analyzer and sonic anemometer (IRGASON). Tube delays, determined by cross-covariance of N2O with vertical wind, were consistent over time and varied between 0.2 and 0.5 s. Spectral and co-spectral analysis of vertical wind, temperature, H2O, CO2 and N2O showed good agreement. Ogive functions demonstrated that the new system has adequate frequency response to capture >90% of the N2O fluxes for a wide range of wind speeds and atmospheric stabilities and is suitable for deployment in remote areas.
Utilizing Libya-4 to intercalibrate overlapping sensors in the same sun-synchronous orbit
Authors: Doelling David , Haney Conor , Khakurel Prathana , Bhatt Rajendra , Scarino Benjamin , Gopalan Arun
Published: March 2024

The NASA CERES observed SW and LW broadband fluxes are utilized by the climate community for monitoring the Earth’s energy imbalance and for climate model validation. The SNPP and NOAA20 CERES instruments and associated VIIRS imagers were launched into the same 1:30 PM mean local time sun-sun-synchronous orbits as well as the future NOAA22 Libera broadband instrument and VIIRS imager. The overlapping sensor records need to be intercalibrated to enable consistent broadband fluxes and imager cloud retrievals. The overlapping satellites are typically placed a half an orbit apart, thus preventing any simultaneous nadir overpass (SNO) events required for time-matched inter-calibration strategies. A Pseudo Invariant Calibration Site (PICS), such as Libya-4, can provide overlapping sensor radiometric scaling factors without the use of SNOs. The clear-sky Libya-4 observed radiances were characterized both spectrally and angularly and corrected for atmospheric effects. The Libya-4 natural variability was found to be consistent across the CERES and VIIRS records. This fact reveals that the sensor onboard calibration anomalies are smaller than the Libya-4 natural variability. By mitigating the Libya-4 natural variability will reduce the radiometric scaling factor uncertainty needed to provide both broadband flux and cloud retrieval continuity across the overlapping sensor records.