bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantification of seawater total alkalinity measurement uncertainty to support the evaluation of ocean alkalinity enhancement
Authors: Capitaine Gaëlle , Fisicaro Paola , Wagener Thibaut
Published: March 2024

Ocean alkalinity enhancement is one approach being considered to contribute to marine Carbon Dioxide Removal techniques. It relies on the addition of alkalinity to the marine environment, either under the form of crushed-rock feedstocks or under a dissolved form. This conducts to the decrease of seawater partial pressure of CO2 (pCO2) allowing seawater, by equilibrium with air, to absorb more CO2 from the atmosphere.In order to determine the amount of CO2 removed from the atmosphere, a monitoring, reporting, and verification (MRV) system of marine carbon dioxide removal needs to be designed. The evaluation of ocean alkalinity enhancement will depend on the monitoring of measurable variables of the marine carbonate system, as well as on numerical simulations. In this context, acquiring accurate and robust data of seawater total alkalinity is highly relevant in order to quantify the background state alkalinity and to check that alkalinity has efficiently been added.In that goal, the application of the three pillars of metrology: metrological traceability, measurement procedure harmonization and validation, and uncertainty estimation, are required. However, up to date, the total alkalinity measurement method lacks of a rigorously established uncertainty budget.The establishment of measurement results uncertainty can be realised by the mean of two approaches. The “bottom-up” approach is the most rigorous way to thoroughly establish an uncertainty budget. It relies on the identification and quantification of each source of uncertainty involved at every step of the measurement process, as described by the Guide to the expression of Uncertainty in Measurements. The “top-down” approach relies on an experimental assessment of the uncertainty, from repeatability, reproducibility and trueness estimates.The presentation will focus on the evaluation of the uncertainty of seawater total alkalinity measurement results using the two approaches aforementioned. The sources of uncertainty originating from the potentiometric titration measurement method, and the mathematical model used for data treatment, will be presented and quantified. This study will also allow identifying which sources have the major contribution to the overall uncertainty budget, and thus the ones we should focus on to lower the uncertainty. The estimation of the uncertainty with the “top-down” approach is determined from an inter-laboratory comparison involving five laboratories, conducted on reference solutions. The developed artificial and natural seawater reference solutions, as well as the results of the inter-laboratory comparison, will be presented. Comparison, advantages and limitations of the two uncertainty estimation methods will be discussed. Finally, the level of uncertainty estimated will be discussed in the frame of MRV system in supporting the evaluation of ocean alkalinity enhancement.
On the usefulness of considering the run-to-run variability for an ensemble prediction system
Authors: Marchal Hugo , Bouttier François , Nuissier Olivier
Published: March 2024

The run-to-run variability of numerical weather prediction systems is at the heart of forecasters' concerns, especially in the decision-making process when high-stakes events are considered. Indeed, forecasts that are brutally changing from one run to another may be difficult to handle and can lose credibility. This is all the more true nowadays, as many meteorological centres have adopted the strategy of increasing runs frequency, some reaching hourly frequencies. However, this aspect has received little attention in the literature, and the link with predictability has barely been explored.In this study, run-to-run variability is investigated through 24h-accumulated precipitations forecasted by AROME-EPS, Météo-France's high resolution ensemble, which is refreshed 4 times a day. Focusing on the probability of some (warning) thresholds being exceeded, results suggest that how forecasts evolve over successive runs can be used to improve their skill, especially reliability. Various possible aspects of run sequence have been studied, from trends to rapid increases or decreases in event probability at short lags, also called "sneaks" or "phantoms", as well as the persistence of a non-zero probability through successive runs. The added value provided by blending successive runs, known as lagging, is also discussed.
What advances monsoon onset over India?
Authors: Goswami Bidyut Bikash , Muller Caroline
Published: March 2024

In the monsoon regions, atmospheric convection is typically stronger over the oceans than over land. Rainfall over land is potentially affected by the dynamic response of the atmosphere to deep convection over the adjacent oceans. Here, we show, in the case of the Indian summer monsoon, that enhanced atmospheric deep convection over the Bay of Bengal ∼2 weeks before onset, advances monsoon onset over India. Since the sea surface temperature of the Bay of Bengal is already hot during spring, warm anomalies further enhance convection that drives a convergence of low-level winds. A part of this circulation response blows from central India to the Bay of Bengal. It paves the way for monsoon circulation over India and advances the onset of monsoon. We tested this hypothesis using an atmospheric model forcing it by warm sea surface temperature anomalies over the Bay of Bengal 10-15 days before monsoon onset.
Lake archives from tropical Africa: Reconstructing the paleoclimate leading to the African Rainforest Crisis 3000 years ago
Authors: Engelhardt Michelle , De Clippele Antoine , Ludjwera Alfred , Haghipour Negar , Six Johan , Drake Travis , De Groot Lissie , Van Oost Kristof , Hemingway Jordon
Published: March 2024

The second largest rainforest biome on Earth lies in the Congo Basin of central Africa. Due to increasing pressure associated with slash-and-burn farming practices as well as climate change, the rainforest may loose its ability to absorb atmospheric carbon. Interestingly, former studies have found evidence for a similar so-called “African Rainforest Crisis” that took place in the late Holocene, around 3000 years ago (Brncic et al. 2009; Garcin et al. 2018). There are some indications that this crisis was caused by the expansion of the Bantu people, who are believed to have migrated to this area to pursue extensive farming at this time. Pollen records, to the contrary, suggest a shift towards a drier climate as the primary mechanism inducing the crisis. Since data from this area are scarce, more information is needed to resolve the exact causes of the African Rainforest Crisis, especially since it is a likely analog for ongoing and future rainforest contraction.To provide such information, we collected a total of about 30 m of core from 13 lakes along the rainforest-savannah boundary in the Kasaï Basin, Democratic Republic of Congo, which constitutes the southwest portion of the Congo Basin. We developed preliminary age models of the sediment records using bulk radiocarbon measurements to compare the estimated sedimentation rates. Two periods of reduced sedimentation rates around 700 and 3500 years before present have been identified. These can indicate the timing and spatial extent of erosive events usually linked to drying and a shift in vegetation. In parallel, we analyse the catchment’s vegetation through time using stable-carbon istopes to distinguish between the abundance of C3 and C4 plants. Additionally, bulk XRF and XRD data offers insights into the underlying mineralogy. First results suggest kaolinitic and quartz-rich sediments, indicating high wethering intensity. By using mineralogy as an indicator of weathering intensity, we expect to draw conclusions on the hydrology and temperature throughout the late Holocene. To further constrain the paleoclimate reconstructions, triple-oxygen isotope analysis on the clay-size fraction and pollen and charcoal analyses are planned. A holistic interpretation will aim to reveal the role of climate vs. land-use change as a trigger of the African Rainforest Crisis, which serves as an analog to better predict how the Congo rainforest will respond to today’s land use- and climate-triggered challenges. REFERENCESBrncic, T. M. et al. (2009) Holocene 19, 79–89.Garcin, Y. et al. (2018) PNAS 115, 3261–3266.
Multi-stage Cenozoic exhumation history of southern Central Tian Shan: implications for geodynamic and sedimentary evolution
Authors: Lyu Lixing , Li Tao , Jia Yingying , Chen Jie
Published: March 2024

Despite important implications for tectonic, sedimentary, geodynamic and climatic evolution in central Asia, Cenozoic exhumation history of the Tian Shan remains highly debated. Here, we report unexpectedly young zircon fission-track and zircon (U-Th)/He dates from the Tomor Peak region in southern Central Tian Shan. Together with new and published biotite 40Ar/39Ar and apatite (U-Th)/He data, the exhumation history since latest Jurassic is reconstructed. An initial increase in exhumation rate from ≤0.01 to ~0.1-0.2 km/Myr occurred at ~25-20 Ma, which is thought to be a response to changed regional stress field due to growth of the Tibetan-Pamir Plateau driven by deep geodynamic processes relating to India-Asia convergence. The second stage of exhumational acceleration took place at ~12-6 Ma, with an apparent rate of ~1.0 km/Myr, which probably relate to the “hard collision” between the Indian lithospheric mantle and the Tarim-Tajik lithospheric mantle beneath the Pamir and western Tibet. After ~5 Ma, the mean exhumation rate of sampled rocks dropped to be ~0.5 km/Myr due to drier climate condition and redistributed strain accompanying the formation of Kuqa foreland thrust system. Finally, based on the presented bedrock exhumation history and available sedimentary records from foreland basins, we propose a coupled tectono-sedimentary evolution model to reconcile the conflicting tectonic interpretations between low temperature thermochronological and sedimentological studies.
The Local and Remote Impacts of Asian Aerosol Forcings on the East Asian Winter Monsoon and ENSO
Authors: Jia Zixuan , Bollasina Massimo , Zhang Wenjun
Published: March 2024

The East Asian winter monsoon (EAWM) is a prominent feature of the northern hemisphere atmospheric circulation during boreal winter, which has a large influence on the weather and climate of the Asian-Pacific region. At interannual time scales, the strength of the EAWM is strongly influenced by the El Niño-Southern Oscillation (ENSO). With the increasing influence of human activities, the greenhouse gas-driven changes in the climate mean state and the interannual variability of the EAWM received widespread attention. However, the impact of anthropogenic aerosols has been considered only in a few studies, which may accelerate or counteract greenhouse gas-driven climatic changes over different regions. Using fixed sea surface temperature and atmosphere–ocean coupled simulations from the Precipitation Driver Response Model Intercomparison Project (PDRMIP), the local and remote impacts of Asian aerosol forcings on the broad East Asian-Pacific region are examined. Results indicate that increased sulfate concentrations over Asia by a factor of 10 strengthen the EAWM through the regional aerosol‐induced cooling first, then extend the EAWM circulation southeastward through the broader cooling over the Maritime Continent and the North Pacific. Remotely, the cooler Northern Hemisphere shifts the Intertropical Convergence Zone (ITCZ) toward the south, and the warmer sea surface temperature (SST) over the equatorial eastern Pacific leads to western-central equatorial Pacific westerly wind anomalies. These changes contribute to the increase in the ENSO’s amplitude, mainly through strengthening the Bjerknes or zonal wind feedback. Furthermore, in response to the increase in extreme El Niño and La Niña frequency, the interannual variability of the EAWM increases, with more extreme strong and weak EAWM years.
Accumulation of natural and artificial radionuclides in cryoconite holes on Alpine glacial environment
Authors: Sala Dariusz , Buda Jakub , Baccolo Giovanni , Cwanek Anna , Błażej Sylwia , Ambrosini Roberto , Di Mauro Biagio , Łokas Edyta
Published: March 2024

Over the last century, alpine glaciers have melted rapidly. According to current climate models, it is predicted that 80% of these glaciers will likely disappear between the 2060s and the 2080s. The storage of natural and anthropogenic contaminants in these ice masses, which might be released with water, creates a potential threat for communities, especially those closely related to glacierised regions, and the surrounding glacier habitats.In recent years, cryoconite – a mineral-organic debris that accumulates on the glacier surface - has been the subject of interest due to its ability to accumulate specific substances, surpassing levels found in other terrestrial ecosystems (e.g., proglacial, sediments, soil, lichens, mosses). This phenomenon is attributed to a combination of natural and anthropogenic factors, yet still not well-studied. The majority of artificial radionuclides released into the environment can be attributed to nuclear reactor accidents like Chernobyl (1986) and the stratospheric global fallout.Our main objective is to comprehensively understand the accumulation of natural (210Pb) and artificial (137Cs, 238,239,240Pu) radioisotopes in cryoconite and identify the different sources of contamination based on isotopic and mass ratios of subject radionuclides. To achieve these objectives, we analysed activity concentrations, their relation with the global and local signals, and their variability between glaciers. Samples were collected from eight glaciers in the European Alps, including the glaciers Blanc, Gries, Mandrone, Pastrze, Preda Rossa, Tsanteleina, Ventina, and Zebrù.The highest values of 210Pb were found in cryoconite from the Ventina and the Zebrù Glaciers (more than 11,000 Bq kg−1). The lowest values of 210Pb in individual samples (
Ash dispersion modelling as a tool to constrain source parameters of past volcanic eruptions
Authors: Plunkett Gill , Mastin Larry , Schwaiger Hans
Published: March 2024

Understanding the relationship between volcanic eruptions and their associated climate response requires a view extending further back than historical records can provide. Polar ice cores offer one of the best continuous records of past volcanism in the form of sulphates and ash particles preserved in the ice. Because of their light scattering effect, these sulphate aerosols are the dominant volcanic product contributing to annual and muti-annual climate perturbations. The ice-core sulphate record underpins our ability to reconstruct the climate forcing potential of past eruptions but translating the sulphate concentrations within polar ice cores to atmospheric sulphate loading requires knowledge of the volcanic source’s latitude and plume height. While geochemical analysis of the ash particles can identify the source volcano, for prehistoric eruptions there is no primary record of plume height information available.Here we assess the efficacy of ash dispersion modelling to predict minimum plume height, eruption season and meteorological conditions for events in which there is knowledge only of the source volcano, ash deposition at a given distal location, and ash grain size and shape. We use the eruption of Novarupta-Katmai 1912 as a case study, as ash from this eruption has previously been identified in the North Greenland Ice Core Project (NGRIP) ice core. Using Ash3d software, we model ash dispersion from Novarupta using historical information about the eruption and meteorology to evaluate the sensitivities of the model to parameters such as total grain size distribution, particle shape, ash cloud concentrations over the deposition site and duration of the suspended ash cloud. Using size and shape data from the NGRIP Novarupta-Katmai ash and randomly sampled values of erupted mass, column height, start dates tied to NCEP-NCAR Reanalysis meteorological data, and eruption duration, we run Ash3d simulations of a large series of eruptions from Novarupta, to compare conditions common to “successful” simulations (i.e., those that deposit ash at NGRIP coring site) with known parameters. Our results show that particle shape and size influence the longevity of the ash cloud, requiring longer simulation runs to ensure deposition is captured. We consider the value and limitations of our approach for reconstructing past volcanic plumes and the potential for further developments to aid in our knowledge of past volcanic impacts on climate.
The November 2023 displacement of the Roncovetro Landslide (RE, Italy) as measured by a small wireless network of Ultra-WideBand (UWB) sensors
Authors: Nannipieri Luca , Favalli Massimiliano , Burrato Pierfrancesco , Devoti Roberto , Bertolini Giovanni , Mucchi Lorenzo , Fornaciai Alessandro
Published: March 2024

The Roncovetro landslide is a complex active earth flow located in the Enza Valley (Emilia-Romagna Region, Italy). It carves the southern flank of Monte Staffola from its summit to the riverbed of Tassobbio stream, with a total involved volume of ~ 3×106 m3. This ~ 2.5 km landslide has a maximum width of 300 m and a 30-40 m wide channel that separates the depletion zone from the accumulation zones. Since the clay fraction is largely dominant, the landslide mainly behaves like a fluid-viscous earthflow. capable of reaching maximum velocities of up to 10 m/day. The perennial activity of the Roncovetro landslide is characterized by phases during which the detachment is limited to deep creep, sliding, and flowing, as well as major events that result in the interruption of the white road between Roncovetro and Vedriano villages.In recent years, the Roncovetro landslide has been selected as a test site for evaluating new monitoring technologies based on Ultra-Wide Band (UWB) wireless sensors. Currently, it has been designated as a study area for the "Land-slide Enhanced Monitoring Network (LEMON)" project funded by the INGV. As part of the LEMON project, a small network of UWB wireless sensors has been installed on the landslide body to monitor its movement. The technology used was previously described in Intrieri et al. (2018) and Mucchi et al. (2018). The installed network consists of five sensors, comprising one master node and four slave nodes. The master node and one slave node were placed outside the area recently affected by displacements, while three nodes were positioned inside the landslide body. The acquisition frequency was set at one acquisition every three hours, totaling eight acquisitions per day.In November 2023, the Roncovetro landslide experienced a significant displacement that once again swept away the white road. This displacement was fully recorded by the UWB network. Additionally, an Unmanned Aerial System (UAS) survey was conducted before and after the displacement to offer a comprehensive view of the movement.In this work, we first describe the technological improvements and updates made to the UWB wireless network compared to previous works. Second, we describe the November 2023 displacement of the Roncovetro landslide as recorded by the UWB network with a frequency of one acquisition every three hours. And finally, we compare the data provided by the UWB network with the changes in the landslide detected through the comparison of pre- and post-UAS-derived orthophotos.
Adapting in situ sampling strategies to SWOT-scale studies: The BioSWOT-Med campaign example as part of the SWOTAdopt-a-Crossover Consortium
Authors: Rousselet Louise , Doglioli Andrea , Petrenko Anne , Barrillon Stéphanie , Berta Maristella , Bosse Anthony , Berline Léo , Fuda Jean-Luc , Rolland Robin , Bouruet-Aubertot Pascale , Gastauer Sven , Grégori Gérald , d'Ovidio Francesco
Published: March 2024

The SWOT satellite measures sea surface height at an unprecedented resolution about ten times better than conventional altimetry products. SWOT data offer a unique opportunity of observing very fine-scale (~few km) surface dynamics from space. In situ samplings, aside from complementing the 2D picture, also provide a 3D view of the observed fine scale dynamics essential for interpretation of bio-physical interaction processes. Nevertheless, exploring this regime during field experiments remains challenging due to the difficulty to precisely locate fine-scale features in real time. A shift of a few km may not be of critical importance when sampling a large structure such as an eddy with a radius of about 100 km. However a similar sampling error could obviously lead to severe misinterpretations in the case of a 10 to 20 km wide eddy. The problem is even exacerbated by the fact that the lifetime typically decreases with the size of eddies and filaments. One way to address this problem with field experiments at the SWOT scales is therefore to update and adapt the sampling location and shape, with synoptic near-real time information of the sea state provided by available high resolution remote sensing (SST and Chlorophyll), and analysis of altimetry and model assimilation. Although vulnerable to cloud coverage and/or limited in resolution, this information can be complemented by near-real time Lagrangian analysis of the surface geostrophic fields providing finer diagnostics of the sampling site dynamics. Early SWOT data also filled some gaps in terms of parameters and spatiotemporal coverage. By using the BIOSWOT-Med cruise as an example, here we review the tools offered by the SWOT AdAC Consortium to the field experiments that have been deployed during the SWOT fast-sampling phase (March-June 2023). After evaluating synergies and shortcomings with in situ platforms, we will discuss how adaptive sampling strategies may evolve in the future to assist field experiments during the SWOT Science phase.
Estimating pollen profiles and assessing relationships with meteorology, air pollutants and vegetation in three cities of India
Authors: Dhankhar Arzoo , Dey Sagnik , J Osborne Nicholas , Darssan Darsy
Published: March 2024

Estimating pollen profiles and assessing relationships with meteorology, air pollutants and vegetation in three cities of IndiaArzoo Dhankhar1, Sagnik Dey2, Darsy Darssan3, Nicholas J Osborne31UQIDAR (University of Queensland, Australia- Indian Institute of Technology, Delhi, India)2Indian Institute of Technology, Delhi3School of Public Health, University of Queensland, Australia Allergy, is, showing an increasing incidence over recent decades across the globe. Less emphasised is the impact of bioaerosols particularly ‘pollen’ on adverse respiratory health effects. India has some of the poorest air quality globally making it an important study area. Regular monitoring of airborne pollen is crucial to know the current prevalence and diversity of potential pollen allergens present in the air column. But most of the LIC and LMICs lack regular pollen monitoring both spatially and temporally.In this study, we collected daily bi-hourly airborne pollen samples from three cities in India (Delhi, Rishikesh and Kolkata) for 5 weeks. These samples were collected using small portable pollen samplers (pollen sniffers). The pollen were counted using microscopy and the results were analysed. The study focused on assessing the relationships between daily pollen counts (total and grass), meteorological parameters (wind speed, relative humidity, temperature, rainfall), vegetation and air pollutants (PM2.5, PM10, NOx, SOx, O3).Poaceae and Chenopodiaceae-Amaranthaceae families were found to be the dominant airborne pollen families at the Delhi site since it was the peak growing season for grasses and weeds. The overall range for total pollen was highest in Rishikesh (300-500 pollen counts) than in Delhi and Kolkata. Among meteorology, rain, temperature, and wind were significantly correlated with bihourly pollen counts with p value < 0.05. Since the cities chosen for the analysis differ in pollution levels, the insights provide a better understanding of pollution and pollen effects.  The study also reflects upon a less explored method of airborne pollen collection, further adding meteorology effects on pollen to the research database. The results will be used to develop prediction model for grass pollen using variables like vegetation and meteorology.Further work will be assessing pollen counts with respiratory health outcomes. The study’s objective is to provide valuable insights that can benefit to the policy makers, health care workers, scientist community and potentially help in reducing health burden of the country along with providing quality life for susceptible citizens.
TFe and SiO2 Spatial Mapping Enhancement in Iron Tailings: Efficiency of a Calibration Transfer Model
Authors: Bao Nisha , Lei Haimei , Cao Yue , Gholizadeh Asa , Saberioon Mohammadmehdi , Peng Yi
Published: March 2024

Iron tailings are crystalline powders predominantly composed of iron (Fe) and silicon dioxide (SiO2). Spatially characterizing of the physical and chemical properties of iron tailings is greatly important for optimal utilization and proper disposal of tailings. Visible–near infrared–shortwave infrared (VIS–NIR–SWIR; 350–2500 nm) spectroscopy offers a rapid, non-destructive, and cost-effective method for quantitatively analyzing tailings properties. The main objective of this study was to map the spatial distribution of total Fe (TFe) and SiO2 content in a tailings dam through the use of laboratory spectra and GF-5 hyperspectral imagery based a calibration transfer model approach. A total of 77 samples were collected from the surface of targeting field and scanned by a laboratory VIS–NIR–SWIR reflectance spectrometer. The competitive adaptive re-weighted sampling (CARS) algorithm was applied to select important spectral features. Subsequently, different spectral indices were calculated to enhance the prediction performance of the calibration models. Rulefit and random forest (RF) algorithms were used to calibrate spectral information with associated tailing properties. The results showed that the Rulefit algorithm with selected feature bands and calculated spectral indices yielded the highest estimation accuracy for TFe (R2 = 0.86, RMSE = 1.30%, LCCC = 0.87 and bias = -0.45) and SiO2 (R2 = 0.74, RMSE = 2.00%, LCCC = 0.84 and bias = 0.38). The direct standardization (DS) algorithm was applied to correct GF-5 hyperspectral images and enhance the efficiency of calibration model transfer process. Finally, the Rulefit models were transferred to corrected GF-5 hyperspectral images for mapping the spatial distribution of TFe and SiO2 contents. Our results demonstrated the possibility of successful transfer of laboratory spectral-based model to the GF-5 hyperspectral imagery for mapping spatial distribution of tailing compositions. This finding can be applied for efficiently recovering valuable metals and minimizing environmental risks. 
Seafloor topography recovery improved by combination of different gravity data functionals
Authors: fuseau david , Seoane Lucia , Ramillien Guillaume , Darrozes José , Plazolles Bastien , Rouxel Didier , Schmitt Thierry , Salaün Corinne
Published: March 2024

Tesseroid and radial columns decomposition of the undersea relief strategies have been considered to recover the seafloor topography by Kalman Filter (KF) inversion of gravity data in the case of the Great Meteor seamount located in the North Atlantic ocean. These both modeling approaches are shown to be equivalent at high grid sampling rate (
Zooplankton Fecal Pellet Flux and Carbon Export in the Deep South China Sea
Authors: Li Jiaying , Liu Zhifei , Lin Baozhi , Zhao Yulong , Zhang Xiaodong , Cao Junyuan , Zhang Jingwen , Song Hongzhe , Blattmann Thomas , Haghipour Negar , Eglinton Timothy
Published: March 2024

Zooplankton fecal pellets constitute a major component of passively sinking particles in the ocean. The sinking of zooplankton fecal pellets provides an efficient vehicle for the transfer and sequestration of particulate organic carbon in the deep sea, which has been widely reported in different ocean regions. However, most existing studies focus on the sinking flux of fecal pellets within the upper ocean, while the lower mesopelagic and bathypelagic zones are rarely investigated. Here, we report the spatiotemporal flux variation of zooplankton fecal pellets collected by two sediment traps deployed in mesopelagic and bathypelagic zones (500 m and 2190 m, respectively) of the southern South China Sea from June 2020 to May 2023. The average fecal pellet numerical flux is 3.21*104and 4.64*104 pellets m-2 d-1 at 500 m and 2190 m, respectively, corresponding to an average fecal pellet carbon flux from 0.43 to 0.84 mg C m-2 d-1 at these two depths. Fecal pellet fluxes display distinct seasonal patterns due to the control of the East Asian monsoon system, with higher fluxes in winter and spring, and lower fluxes in summer and autumn. Higher fecal pellet fluxes combining with the presence of extra-large pellets are found in bathypelagic zone, which is attributed primarily to in-situ reworking and repackaging of sinking particulate matter by deep-dwelling zooplankton communities, as well as lateral inputs from adjacent high productive continental coasts and shelves. We compare our results with global deep-sea (>500 m) fecal pellet flux data reported from different sediment-trap stations with distinct marine primary productivity and zooplankton biomass. Furthermore, we will report on the state of our progress on carbon isotope analysis (13C, 14C) for disentangling the source-to-sink dynamics of fecal pellets and its role in the deep-sea carbon export and sequestration.
Multiple lines of evidence help identify the sources of Nitrogen and Carbon in particulate matter sampled in the historical center of Naples (Italy)
Authors: Rubino Mauro , Sirignano Carmina , Chianese Elena , Hernández-Ceballos Miguel Anguel , Riccio Angelo
Published: March 2024

Attribution of nitrogen (N) and carbon (C) origin in atmospheric particulate matter (PM) is one of the main focuses of scientific research in the field of air pollution. Here we show how using multiple pieces of information from different techniques, including concentrations of major ions (NO3-, NH4+, NO-, SO42-, etc…), concentration and isotopic composition of total N (δ15N) and total C (δ13C), characterization of the meteorology, and using state of the art models of atmospheric circulation (Hysplit) and weather prediction (WRF) help understand the causes of PM change in the atmosphere sampled over the historical town of Naples (Italy).PM samples were collected in May 2016 and November 2016 – January 2017 within the ARIASaNa project. The project was led by the Italian National Research Center (CNR), in collaboration with the Parthenope University and was aimed to monitor air pollution in the main towns of the Campania region. Fine particles with diameter < 2.5 μm (PM2.5) and < 10 μm (PM10) were collected for 24h on pre-cleaned (700 °C for 2 h) quartz filters (Whatman, 47 mm diameter) on top of the historical building complex in Largo San Marcellino (lat. 40.85° N; long. 14.26° E, 53 m.a.s.l.).The results show some key features:All species (major ions and isotopic compositions) measured in autumn-winter samples are much less variable than those measured in spring. This seems to be related to a change in weather pattern which is caused by the land-sea breeze mechanism.
A significant change of the main species measured is found around the middle of May 2016. This change occurs at the same time as a change in the meteorology of the area, going from high to low pressure.
The change found in May 2016 is characterized by a strong positive relationship between ammonium (NH4+) concentration and the isotopic composition of nitrogen (δ15N), suggesting that the dominant factor of change in atmospheric N chemistry is the NH4+ origin.
We will discuss the results obtained in terms of influence of the meteorology on atmospheric chemistry of N and C, and will try to disentangle the changes due to secondary atmospheric processes from those caused by a change in the primary source of N and C.
(Un)certainties in tectonic stylolite stress inversion
Authors: Köhler Saskia , Koehn Daniel
Published: March 2024

Over the last two decades application of stylolite roughness inversion has become a common tool to reconstruct paleostress-fields, stress magnitudes and burial depth. While the orientation of the highest principal stress is free of any doubt, there are uncertainties coming along with tectonic stylolite inversion that require a differentiated debate. This includes data quality, rock physical parameters, timing of stylolite growth and burial depth.We present results of statistical data analysis, showing that data quality depends on the number of samples as well as on the sample size. Thus, the dataset can be of very high quality and stable in outcrop scale. This is faced by field and microscopic observations and results of the stress inversion itself, that demonstrate that some common assumptions, i.e. that modelled paleodepth can be used for tectonic stylolite inversion, are not generally valid. We want to open the discussion towards the question of how we can refine such assumptions and parameters for our paleo stress models and better prediction of recent deformations. 
Data-driven surrogate-based Bayesian model calibration for predicting vadose zone temperatures in drinking water supply pipes
Authors: Kröker Ilja , Nißler Elisabeth , Oladyshkin Sergey , Nowak Wolfgang , Haslauer Claus
Published: March 2024

Soil temperature and soil moisture in the unsaturated zone depend on each other and are influenced by non-stationary hydro-meteorological forcing factors that are subject to climate change. 

The transport of both heat and moisture are crucial for predicting temperatures in the shallow subsurface and, as consequence, around and in drinking water supply pipes. Elevated temperatures in water supply pipes (even up to 25°C and above) pose a risk to human health due to increased likelihood of microbial contamination. 

To model variably saturated flow and heat transport, a partial differential equation (PDE)-based integrated hydrogeological model has been developed and implemented in the DuMuX simulation framework.  This model integrates the hydrometeorological forcing functions via a novel interface condition at the atmosphere-subsurface boundary. Relevant soil properties and their dependency on temperatures have been measured as time series at a pilot site at the University of Stuttgart in detail since 2020. 

Despite these efforts on measurements and model enhancement, some uncertainties remain. These include capillary-saturation relationships in materials where they are difficult to measure, especially in the gravel-type materials that are commonly used above drinking water pipes. 

To enhance our understanding of the underlying physical processes, we employ Bayesian inference, which is a well-established approach to estimate uncertain or unknown model parameters. Computationally cheap surrogate models allow to overcome the limitations of Bayesian methods for computationally intensive models, when such surrogate models are used in lieu of the physical (PDE)-based model. Here, we use the arbitrary polynomial chaos expansion equipped with Bayesian regularization (BaPC).  The BaPC allows to exploit latest (Bayesian) active learning strategies to reduce the number of model-runs that are necessary for constructing the surrogate model.  

In the present work, we demonstrate the calibration of a PDE-based integrated hydrogeological model using Bayesian inference on a BaPC-based surrogate.  The accuracy of the calibrated and predicted temperatures in the shallow subsurface is then assessed against real-world measurement data. 
Developing Best Practices in Tidal Analysis
Authors: Matthews Andrew ,   IAPSO Tidal Analysis Best Practice Study Group
Published: March 2024

The tide is generally the dominant component of a sea level record in many parts of the world and its analysis has therefore been a central part of oceanography for hundreds of years. Methods to predict the tide have changed over time, but have largely converged on the classical harmonic method, which is based on the principle that a series of tidal observations may be decomposed into a finite number of sinusoidal functions, known as tidal constituents, with angular speeds related to known astronomical frequencies.Classical harmonic analysis is usually carried out using one of a number of software packages made available by scientists and oceanographic institutions. These are exceptionally useful, but within them they encode a series of assumptions and decisions that need to be made in order to carry out an analysis, including:What is an appropriate set of constituents to use in a location, given the data available and the hydrodynamics of the area?
How does the analysis account for variations of the tidal constituents over time, for example over the nodal cycle?
How will our results be affected by non-tidal influences?
Furthermore, other approaches will be more successful in particular environments, for example in shallow waters when the tidal curve can be highly non-symmetric.Non-experts in tidal science are often unaware of the options available, and the consequence of making the wrong decision. Furthermore, this knowledge is developed as rules-of-thumb within organisations based on many years of experience, so is not readily accessible. As a result, there is a need for some internationally agreed recommendations.We recently held a tidal analysis workshop to discuss these matters, funded by the International Association for the Physical Sciences of the Oceans (IAPSO) as one of their Best Practice Study Groups. Here we present some illustrations of the issues mentioned above, along with some of our suggested approaches.The best practice document is currently being drafted based on discussions held at the workshop, and when completed will be submitted to the International Oceanographic Commission’s best practice system (https://www.oceanbestpractices.org/).
Numerical and experimental investigation on the effect of topography on the hydrodynamics of planetary fluid envelops.
Authors: Giraud Vadim , Noir Jérôme , Burmann Fabian , Cébron David
Published: March 2024

The majority of investigations into planetary core and subsurface ocean dynamics have traditionally assumed a perfectly smooth interface. However, geodynamical models and seismic observations on Earth suggest the presence of topography. This study addresses the role of topography in the simplified but fundamental case of differential rotation between the topography and the fluid within a cylinder.
We conducted numerical and experimental analyses, exploring various ranges of Rossby numbers (from 10-1 to 10-4 ) and different wavelengths and heights of topography, always greater than the Ekman boundary layer. Numerical simulations were performed using the spectral elements code Nek5000, while experiments were conducted with water on a rotating table employing particle imagery velocimetry (PIV).
Our observations reveal that the topography emits inertial waves into the fluid, and their patterns are correlated with the derivatives of the topography's height, rather than directly with its height. The controlling parameters influence the frequencies and amplitudes of the inertial waves, leading to the derivation of scaling laws in Rossby number, wavelength, and topography height. From these scaling laws, we propose a model for the dynamics of the fluid, including energy transfers.

 
 
 
Analysis of radiocarbon in atmospheric methane: technological advances and interpretation of measurements
Authors: Zazzeri Giulia , Wacker Lukas , Haghipour Negar , Graven Heather
Published: March 2024

Radiocarbon (14C) is an optimal tracer of methane emissions, as 14C measurements enable distinguishing fossil from biogenic methane. However, we are not yet applying these measurements in monitoring programs for quantification of sources contribution, because of the technical challenges associated with the 14C analysis and the bias introduced by 14C emissions from nuclear power plants.Studies in London and in Switzerland demonstrate how the nuclear influence should be accurately modelled for a quantitative interpretation of 14C measurements and that a robust uncertainty estimate of the fossil and biogenic proportion of CH4 emissions is highly needed.Here we present the technological advances in the 14CH4 analysis, including the achievement of high precision 14CH4 measurements (5 ‰) using a new portable sampler developed at the laboratory of Ion Beam Physics, and the potential of expanding these measurements for an improved understanding of sources. We will present the first quantification of fossil methane emissions in London using 14C, demonstrating that, by increasing the measurement capability, we can use 14C to constrain the methane budget at regional scale.
Subinertial Variability in Four Southeast Greenland Fjords in Realistic Numerical Simulations
Authors: Gelderloos Renske , Haine Thomas , Almansi Mattia
Published: March 2024

Natural variability at subinertial frequencies (time scale of several days) plays an important role in the interaction between Greenland’s fjords, the continental shelf, and shelf-break exchange with the deep basins. In this study we identified the nature and driving mechanisms of this variability in four fjords in Southeast Greenland, in three high-resolution numerical simulations. We find two dominant frequency ranges in along-fjord velocity, volume transport of Atlantic Water, and along-fjord heat transport: one around 2–4 days and one around 10 days. The higher frequency is most prominent in the two smaller fjords (Sermilik Fjord and Kangerdlugssuaq Fjord), while the lower frequency peak dominates in the larger fjords (Scoresby Sund and King Oscar Fjord). The cross-fjord structure of variability patterns is determined by the fjord's dynamic width, while the vertical structure is determined by the stratification in the fjord. The dominant frequency range is a function of stratification and fjord length, through the travel time of resonant internal Kelvin waves. We find that the subinertial variability is the imprint of Coastal Trapped Waves, which manifest as Rossby-type waves on the continental shelf and as internal Kelvin-type waves inside the fjords. Between 50% and 80% of the variability in the fjord is directly forced by Coastal Trapped Waves propagating in from the shelf, with an additional role played by alongshore wind forcing on the shelf.
Palaeohydrology and Fluvial Intermittency in the Eocene Hothouse: Castissent Formation, Southern Pyrenees
Authors: McLeod Jonah , Whittaker Alexander , Bell Rebecca , Hampson Gary , Fuller-Field Oliver , Prieur Marine , Valero Luis
Published: March 2024

River discharge patterns are sensitive to changing precipitation as a result of evolving climates. In stratigraphy, the intermittency factor (If) of ancient rivers can help illuminate landscape dynamics in the past. The If is recorded in the geologic archive as the ratio of average transport rates (from long-term records of water or sediment flux) versus instantaneous maximum transport capacities if they were to be sustained over the same period, and applying intermittency calculations to stratigraphy can reveal how rivers and landscapes recorded and responded to external tectono-climatic forcings. Here we explore the Lower Eocene Castissent Formation of the Southern Pyrenees, Spain, a strongly progradational fluvio-deltaic succession deposited during the Early Eocene Climatic Optimum (EECO), an intense warm period analogous to potential future climate scenarios. We first reconstruct the depositional volumes of the Castissent Formation in the Tremp-Graus Basin and its equivalent marine successions in the Ainsa and Jaca Basins. We then compare these to estimates of instantaneous water and sediment fluxes using field-based quantitative palaeohydrology approaches.  From these reconstructions, we derive fluvial intermittency factors which we compare to river data for a range of climate conditions. Further, we present detailed reconstructions of morphodynamics in these lower Eocene rivers during the EECO. These results add to growing understanding of intermittency in the geologic past, and reveal the sensitivity of rivers and landscapes to climate forcing in a warm world analogue.  
Folding of subducting slabs controls their deep thermal structures in the mantle transition zone 
Authors: Garel Fanny , Cerpa Nestor , Čížková Hana , Vergeron Xavier , Arcay Diane , Lallemand Serge , Cadio Cécilia
Published: March 2024

The thermal structure of slabs is thought to be a key parameter for deep-focus earthquakes in subduction zones, since most proposed mechanisms, such as transformational faulting, dehydration reactions or shear instabilities, are controlled by temperature. However, the classical (shallow) thermal parameter "phi", associated to the downward advection of isotherms and approximated as slab age x sinking velocity (Kirby et al., 1996), does not explain deep-focus seismicity occurring in relativelty “hot” subduction zones, e.g. under Bolivia. On the other hand, the various morphologies if subducting slabs imaged by seismic tomography reveal reveal the diversity of slab deformation histories in the transition zone as they reach the high-viscosity lower mantle, e.g. folding, deflection, vertical piling. Using numerical models of subduction dynamics, we propose here to characterize the spatio-temporal evolution of deep thermal structures of subducted slabs throughout various subduction scenarios. We investigate how the maximum depth reached by a given isotherm vary through time (up to 200 km for a given subduction zone). In particular, we evidence the key control of the history of slab-folding in the transition zone (folding amplitude and frequency), associated to e.g. slab viscosity and buoyancy. Hence the past dynamics of subduction zones, in addition to present-day subduction parameters, has to be taken into account to predict slabs thermal structures. This work is part of ANR project RheoBreak (ANR-21-CE49-0009).