bluuebunny/crossref_metadata_2025 huggingface dataset:
The shear deformation zone along the KTFZ: implications for faulting properties
Authors: Karakostas Vasileios , Papadimitriou Eleftheria
Published: March 2024

The Kefalonia Transform Fault Zone (KTFZ) in central Ionian Islands (Kefalonia and Lefkada Islands), Greece, a dextral strike slip transform zone, exhibits the fastest rates of relative plate motion in the Mediterranean. Strong (Mw>6.0) earthquakes associated with the fault segments comprised in KTFZ are frequent as historical information and instrumental record reveals. Four main shocks of this order magnitude, among other earthquakes of Mw>5.0 occurred since 2003 on almost along strike adjacent fault segments, with high aftershock productivity extended far beyond the fault tips forming aftershocks zones remarkably wider than expected of strike slip faulting. This enhanced aftershock seismicity is associated with the shear deformation zone surrounding the mainshock rupture plane. It has been suggested that it results from the reactivation of secondary faults, its width decreases as a power law with cumulative fault displacement being narrower around mature faults than around immature faults. As the structural maturity may have a strong impact on earthquake behavior, such as magnitude, stress drop, distribution of slip, rupture velocity, ground motion amplitude, and number of ruptured segments, as prior studies have suggested, we aim at investigating the shear deformation zone along KTFZ. We used the relocated aftershock seismicity of the four recent (2003 – 2015) strong (Mw>6.0) main shocks that occurred on almost along strike positioned strike slip faults for defining the fault width in conjunction with the fault length, as we have already done in the case of the 2015 Lefkada main shock, and the activation of secondary faults, most probably triggered by stress changes and stress redistribution due to the main shock coseismic slip. Detailed slip models, when available, are engaged for this scope for investigating possible triggering of the secondary fault segments taking part in each seismic excitation, due to the stress transfer, taking also into account the stress sensitivity on the geometry and faulting properties of the minor faults, along with the accurately relocated aftershock seismicity. After the main fault width definition, we investigated the decrease of aftershock frequency and spatial density as a function of distance from the main fault.Acknowledgments: Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or European Commission – Euratom. Neither the European Union nor the granting authority can be held responsible for them.
Identifying the natural and agricultural impacts on the glaciochemistry of the Aru ice core on the northwestern Tibetan Plateau
Authors: Yang Dandan , Yao Tandong , Wu Guangjian
Published: March 2024

Glaciochemical data sourced from ice cores in polar regions and the Alps have been extensively examined. However, quantitative studies on glaciochemical records of the Tibetan Plateau (TP) are scarce. To address this, we investigated annual variations in the major soluble ions (Ca2+, Mg2+, Na, K, NH++4+, Cl−, NO3−, and SO42−) in the Aru ice core on the northwestern TP from 1850 to 2016. Applying a positive matrix factorization model, the sources of the major soluble ions and three factors to evaluate natural and agricultural impacts were identified. Factor 1, crustal dust with high loadings of Mg2+ (81.9%) and Ca2+ (68.7%), significantly positively correlated with wind speed and significantly negatively correlated with δ18O and net accumulation recorded by the ice core, suggesting that strong winds contributed to crustal dust transport from arid and semi-arid regions of Central Asia and deposition in the Aru glacier. However, relatively warm and wet climate prevented the transport of crustal dust. Factor 2 comprised salt lakes with high dominant loadings of Na (75.3%), SO+42− (64.1%), Cl− (60.8%), NO3− (52.2%), and K (49.4%). Declining lake water levels exposed salt lake minerals, which were carried to glaciers under the dynamic conditions of strong winds, whereas warming resulted in an expansion of glacial meltwater and lake water volume, which decreased the contribution of salt lake sediments. Therefore, the contribution of salt lake deposition decreased. Factor 3 was agricultural sources with a high loading of NH+4+ (82%), whose trend aligned closely with the population number and N productions from agricultural sources in South and Central Asia, suggesting that NH3 emissions from agricultural practices are a critical contributor to Factor 3. This study quantified the proportional contribution of natural and agricultural sources to glaciochemical composition, advancing our understanding of glaciochemical records in ice cores from source recognition to quantification.
Estimating Breakpoints between Climate States in Paleoclimate Data 
Authors: Larsen Kathrine , Bennedsen Mikkel , Hillebrand Eric , Koopman Siem Jan
Published: March 2024

This study presents a statistical approach for identifying transitions between climate states, referred to as breakpoints in the econometric literature, using well-established econometric tools for breakpoint detection. We analyze a record of the stable oxygen isotope ratio 𝛿18O, covering 67.1 million years, derived from benthic foraminifera. The dataset is presented in Westerhold et al. (2020) [Science 369, 1383-1387], where the authors use recurrence analysis to identify six climate states: Warmhouse I, Hothouse, Warmhouse II, Coolhouse I, Coolhouse II, and Icehouse, and thus five transitions.
Estimation necessitates a constant observation frequency. We employ mean binning. We explore three model specifications. The first model is a state-dependent mean model, which is equivalent to modeling an abrupt break in the mean of 𝛿18O for each climate state. The second model expands this by including a state-independent autoregressive term, which can be interpreted as making the transitions between states more gradual. The final model expands on the second model by letting the autoregressive term be state-dependent as well, allowing for state-specific autoregressive dynamics. All models incorporate an error term with state-dependent variance.
Fixing the number of breakpoints to five, the resulting breakpoint estimates closely align with those identified by Westerhold et al. (2020) across various binning frequencies and model specifications, demonstrating the robustness of the approach and corroborating the dating of the climate states of Westerhold et al. (2020) with time series analysis. Our approach offers the advantage of constructing confidence intervals for the breakpoints, providing a measure of estimation uncertainty, and it allows testing for the number of breakpoints in the time series.
In conclusion, our study presents a statistically rigorous approach to identifying transitions between climate states as well as their confidence intervals and the number of breakpoints.
The Transition from Granular Debris Flow to Bedload: a force balance perspective
Authors: Koa Islam , Recking Alain , Gimbert Florent
Published: March 2024

Sediment transport can occur in a so-called “debris flow” form, where concentrations are high and movement is driven by gravity. Previous studies have predominantly used simple rheological fluids or uniform granular materials to study the characteristics of debris flows. However, a fundamental question remains regarding the characteristics of the complex granular debris flow, and the transition from granular debris flow to bedload remains poorly understood. In this contribution, we present an experiment in the laboratory where this phenomenon could be studied. Our experiment setup, a 6-meter-long wooden flume, involved a 1 m-long low-slope trapezoidal storage area and a 5 m-long and 0.1 m-wide wooden flume channel inclined at 33%, equipped with a force plate and hydrometer sensors. Our observations show that self-formed, highly concentrated sediment accumulation in the storage area, influenced by flow rate, generates pulses that exhibit three phases: the tail phase containing sand particles, the body phase containing a mixture of particles, and the front phase containing coarse particles. As discharge was dynamically increased, two distinct domains controlled by the forefront coarse particles were observed. Firstly, at low flow (0.14-0.16 l/sec), a static-dynamic domain is identified, characterized by a high sediment concentration and very low velocity. This generates a high resultant force magnitude that affects the forefront coarse particles, resulting in debris-flow-like pulses controlled by the sediment density. Secondly, at higher flows (0.17–0.24 l/sec), a full-dynamic domain is identified, characterized by a lower sediment concentration and very high velocities. This behavior generates hyperconcenrated flow-like pulses controlled by momentum transfer between the pulse phases. We demonstrated that the transition from debris and hyperconcentrated flow to bedload is controlled by the coarse particle’s mobility, whose threshold discharge in clear water was 0.22 l/sec. The important role played by the sand fraction is also demonstrated, which permits the static dynamics behavior by ensuring momentum transfer either directly, by mass transfer, or indirectly by reducing the medium porosity.
Intercomparison of Tropospheric and Stratospheric Mesoscale Kinetic Energy Resolved by the High-Resolution Global Reanalysis Datasets
Authors: Li Ziyi , Wei Junhong , Bao Xinghua , Sun Y. Qiang
Published: March 2024

This talk will present our recent published study of Li et al. (2023, QJ). With the development of advanced data assimilation and computing techniques, many modern global reanalysis datasets aim to resolve the atmospheric mesoscale spectrum. However, large uncertainties remain with respect to the representation of mesoscale motions in these reanalysis datasets, for which a clear understanding is lacking. The aforementioned challenges have served as a strong motivation to reveal and quantify their mesoscale differences. This study presents the first comprehensive global intercomparison of the tropospheric and stratospheric mesoscale kinetic energy and its spectra over two selected periods of summer and winter events among six leading high-resolution atmospheric reanalysis products: European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis v5 (ERA5), China Meteorological Administration Reanalysis (CRA), Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA2), National Centers for Environmental Prediction's Climate Forecast System version 2 (CFSv2), Japanese 55-year Reanalysis (JRA-55), and ECMWF Reanalysis-Interim (ERA-I). A state-of-the-art global operational model is adopted as a supplementary reference. Although all reanalysis datasets can reproduce broad distribution characteristics that are grossly consistent with the 9 km model, there are substantial discrepancies among them in magnitudes. The ability to capture mesoscale signals is closely linked to their resolutions, but it is also impacted by other factors, including, but not limited to, the selected types of energy, seasons, altitudes, latitudes, model diffusions, parametrization schemes, moist condition, assimilation methods, and observation inputs. Moreover, all datasets illustrate conclusive behaviors for the prevalence of the rotational component in the troposphere, whereas only very few products fail to exhibit the dominance of the divergent component in the stratosphere. Overall, stratospheric ERA5 and CFSv2 outperform the other reanalysis datasets, and only these two can reproduce the feature of the canonical kinetic energy spectrum with a distinct shift from a steeper slope (approximately −3) at lower wave numbers to a shallower slope (approximately −5/3) at higher wave numbers. In addition, the relative disparities among datasets increase dramatically with height, and they are more pronounced in the divergent component. It is also found that the correlations among these datasets are much weaker in the Tropics.Reference:
Li, Z., J. Wei, X. Bao, and Y. Q. Sun, 2023: Intercomparison of tropospheric and stratospheric mesoscale kinetic energy resolved by the high-resolution global reanalysis datasets. Quarterly Journal of the Royal Meteorological Society, 149(757), 3738–3764, https://doi.org/10.1002/qj.4605.
Investigation of the mineralogical composition of desert dust particles during a transboundary pollution episode in the UK and implications for health effects 
Authors: Solomos Stavros , Mitsakou Christina , Thompson Samuel , Macintyre Helen , Exley Karen , Aldridge Stuart , Zerefos Christos , Bartsotas Nikolaos S. , Kalogeri Christina , Spyrou Christos
Published: March 2024

Toxicological and epidemiological studies have supported links between desert dust particles and health impacts, such as worsened asthma, hospitalization for respiratory infections, and seasonal allergic rhinitis. Airborne desert dust particles could serve as a medium for interacting with chemicals on their surfaces, potentially enhancing the bioreactivity of fine particles during episodes of dust storms. The role of the different mineralogical composition (e.g. quarz, iron, feldspars) on the biological effects of mineral dust remains to be determined. In this work we analyze the severe dust event that affected the UK on 15 and 16 March 2022 in terms of the synoptic situation leading to this event, the spatiotemporal distribution of the dust plumes over UK and the chemical/mineralogical composition of the particles. We employ the METAL-WRF model to investigate the atmospheric properties and the quantification of particle concentrations in ambient air but also in dry and wet depositions of dust. The METAL-WRF model includes prognostic fields for ten (10) minerals: illite, kaolinite, smectite, calcite, quartz, feldspar, hematite, gypsum, phosphorus and iron. We also investigate the health impacts linked to the desert dust transport on the population in UK regions. Our results are discussed across similar findings at more frequently dust-affected regions such as the Mediterranean.  Acknowledgment This study is partially supported by the Hellenic Foundation for Research and Innovation project Mineralogy of Dust Emissions and Impacts on Environment and Health (MegDeth - HFRI no. 703) and the project Bioclimatic urban design for the sustainability and resilience of the urban environment in the context of climate change (BIOASTY)
Long term changes in fog frequency at Swedish airports and its potential drivers
Authors: Sporre Moa K. , Hartman Linda , Singh Shubham , Friberg Johan
Published: March 2024

Fog can substantially impact air traffic by inhibiting or aggravating take-off or landing. This can result in large economical costs and even loss of human lives. In this study we investigate how fog frequency has changed at Swedish airports over time. The large north-south extent of Sweden with strong gradients in aerosol concentrations makes it an interesting study area for aerosol impact on fog. We base the study on visibility data from 14 airports. Most visibility data from the airports start in the 1970s but some stations have data before this and some have measurements that start in the 1980s. The visibility measurements are combined with data on air temperature, wind speed, wind direction, and air pressure from the airports. In the study we also include measurements aerosol proxies, namely SO2 in the air from 4 stations and SO42- in rainwater from 10 stations in Sweden. Moreover, emission data of SO2 from Europe from 1970 to present day has been analysed. The analysis shows that the fog frequency changes in Sweden vary with location of the airport. At four airports in southern Sweden, the fog frequency show a statistically significant decrease when comparing the periods before and after 1995. The most prominent changes has occurred at the airports close to Malmö and Gothenburg. The annual fog frequency for these stations changes from 5-6 % in the 1980s to 3-4 % in the 2010s with higher changes during winter. For the airports located further north there is no decrease in fog frequency. Some airports in the northern part of Sweden show a statistically significant increase in fog frequency, though the fog frequencies are lower there than in southern Sweden. We find that the fog frequency changes in Southern Sweden correlate well with changes in air of SO2, rainwater SO42- concentrations, which both show strong decreases since the 1970 and 1980s in southern Sweden. The changes in these concentrations are much weaker further north in Sweden. The fog frequency changes in southern Sweden thus seems to be driven by changes in the load of hygroscopic aerosol. The fog changes in northern Sweden correlate well with temperature, which is increasing at all airports. The rising temperatures in the north could contribute with more favorable conditions for fog formation at these airports where it previously was to cold for fog formation during parts of the year. Out results indicate that the work on air pollution mitigation in Europe over the past 50 years has reduced fog impact on air traffic in southern Sweden.    
Solar park impacts on plant biomass and earthworm and nematode communities
Authors: Scholten Luuk , De Deyn Gerlinde , de Goede Ron
Published: March 2024

Solar parks are a rapidly expanding novel land use primarily to produce renewable energy. However, the aim is to make them multifunctional, and limit negative impacts on soils or even improve soil quality. Solar panels change the microclimate and cause shading below the panels, influencing plant growth and carbon and water inputs to the soil, with potential cascading effects on the soil biota. This research aimed to test the effect of solar panels on earthworm and nematode communities in 12 solar parks with contrasting designs across the Netherlands. Earthworm abundance and diversity, plant biomass and nematode abundance were measured between (gap) and below the solar panels. Nematode abundance was also measured at the highest and lowest edges of the panels. Plant biomass, nematode abundance and earthworm abundance were all significantly lower below the solar panels compared to in the gap between the panels. Nematode abundance at the highest and lowest edges showed intermediate numbers compared to the gap and below the panels. These results show that solar parks have a large impact on the soil biota and stress the need for guidelines for ecologically sound solar park designs to prevent soil damage.
Site-Specific Thresholds for Storm-Driven Compound Flooding in UK Estuaries
Authors: Lyddon Charlotte , Chien Nguyen , Vasilopoulos Grigorios , Ridgill Michael , Moradian Sogol , Olbert Indiana , Coulthard Thomas , Barkwith Andrew , Robins Peter
Published: March 2024

Estuarine flooding is driven by extreme sea-levels and river discharge, either occurring independently or at the same time, or in close succession to exacerbate the hazard, known as compound events. Estuaries have their own dynamics, and different behavior means flooding will occur under different conditions. Recent UK storms, including Storm Desmond (2015) and Ciara (2020), have highlighted the vulnerability of mountainous Atlantic-facing catchments to the impacts of compound flooding including risk to life and short- and long-term socioeconomic damages. There is a need to identify site-specific thresholds for flooding in estuaries, which represent the magnitude of key drivers over which flooding occurs, to improve prediction and early-warning of compound flooding.In this study, observational data and numerical modelling were used to reconstruct the historic flood record of an estuary particularly vulnerable to compound flooding (Conwy, North Wales). The record was used to develop a method for identifying combined sea level and river discharge thresholds for flooding using idealised simulations and joint-probability analyses. Only 6 records of known flooding are identified in the official record. The key limitation of using historic records of flooding is that not all flooding events have been documented, and there are gaps in the record. Therefore, this research also identified the top 50 extreme sea-level and river discharge events in the historic gauge measurements in the estuary, and cross-checked these against online sources using web scraping to establish if these additional 100 extreme events also led to flooding. A more comprehensive historic record of flooding allows more accurate thresholds for flooding to set in each estuary.Caesar-LISFLOOD, a hydrodynamic flow and morphological evolution model, is used in a sensitivity test to simulate inundation under different idealized sea-level and river discharge conditions to further isolate accurate thresholds. The variation in flooded area from a baseline scenario is used to capture flood magnitude associated with each scenario. The results show how flooding extent responds to increasing total water level and river discharge, with notable amplification in flood extent due to the compounding drivers in some circumstances, and sensitivity due to a 3-hour time-lag between the drivers. Joint probability analysis is important for establishing compound flood risk behaviour. Elsewhere in the estuary, either sea state (lower-estuary) or river flow (upper-estuary) dominated the hazard, and single value probability analysis is sufficient. These methods can be applied to estuaries worldwide to identify site-specific thresholds for flooding to support emergency response and long-term coastal management plans.
Combined Impacts of Weather Conditions and COPD on the Risk for Community-Acquired Pneumonia
Authors: Brenner Thomas , Link Ann-Christine , Reudenbach Christoph , Bendix Jörg , Weckler Barbara , Pott Hendrik , Rupp Jan , Witzenrath Martin , Rohde Gernot , Pletz Mathias , Bertrams Wilhelm , Schmeck Bernd
Published: March 2024

Community-acquired pneumonia (CAP) is one of the most frequent causes of death among infectious diseases worldwide. Analyzing a dataset of 5,223 CAP patients in a German multicenter cohort study, our research uniquely explores the twofold combined impact of meteorological conditions, air quality conditions, and pre-existing chronic obstructive pulmonary disease (COPD) on CAP admissions. Both the twofold compound effect of absolute values of meteorological and air quality conditions and, even more, their day-to-day changes significantly influence CAP admissions. Our study emphasizes the important role of air quality conditions over meteorological conditions in contributing to increased CAP admissions, with these weather conditions exerting their influence with a lag time of approximately three to four days. Individuals with pre-existing COPD face the highest risk of CAP admission in the general cohort. The implications of our findings extend to supporting at-risk individuals through protective measures and providing healthcare providers with valuable insights for resource planning during pneumonia-inducing weather conditions.
Cloud property retrieval based on DISAMAR: implications of differences between Oxygen-A and Oxygen-B band data from TROPOMI on Sentinel 5P
Authors: Zhang Xiaoyun , Wang Ping , Stammes Piet , Xie Tao , Lu Feng , Sneep Maarten
Published: March 2024

DISAMAR (determining instrument specifications and analysing methods for atmospheric retrieval) is a computer model developed to simulate the retrieval of properties of atmospheric trace gases, aerosols, clouds, and the ground surface from passive remote sensing observations in a wavelength range from 270 to 2400 nm. It is being used for the TROPOMI/Sentinel-5P and Sentinel-4/5 missions to derive Level-1b product specifications. It is also used  in some research to obtain aerosol and trace gas properties, but its application to cloud properties retrieval is limited. This study presents the retrieval of cloud pressure and cloud optical thickness as well as surface pressure for cloud free based on TROPOMI Oxygen-A (Band 6) and Oxygen-B (Band 5) band measurements, and compares the results with FRESCO and NPP-Suomi Level 2 cloud property data. Different cross section datasets including JPL2008, HITRAN 2008 and HITRAN2020 are also tested in this study. In conclusion, for surface pressure retrieval, using O2-A band gives more reliable results than O2-B band and is easier to converge in the calculation, especially over land surface. But while over sea surface, using O2-B band in retrieval performs better than O2-A band. Secondly, the retrieval based on the cross section file JPL2008 shows better results when using O2-A band, but HITRAN2020 gives better results when using O2-B band. Thirdly, setting appropriate a-priory value in DISAMAR and removing some of the wavelengths with high residual simulated reflectivity can significantly improve the results , both in terms of convergence and reduction of validation error. The cloud pressure correlation coefficient between the retrieval and NPP or FRESCO data is 0.85 and 0.99 respectively, while the cloud optical thickness has a correlation coefficient of 0.77 between retrieval and NPP COT datasets.
The sedimentary record of the Junquera salt marsh (Nalón estuary, N Spain): a tale about contemporary fluvial processes, mining pollution and land-use changes
Authors: Gardoqui Jon , Cearreta Alejandro , García-Artola Ane , Irabien María Jesús , Gómez-Arozamena José , Villasante-Marcos Víctor , Galaz-Samaniego Carlos , Peñalba Cristina
Published: March 2024

Current climate change is causing profound environmental changes in coastal ecosystems, such as rising temperatures, increased precipitations and extreme weather events, including flooding. The stratigraphic record of the salt marshes of northern Spain constitutes a unique archive for exploring natural and anthropogenic processes and dynamics. While salt marshes located along the northeastern margin of Spain have received considerable attention in the scientific literature, those located in the northwestern sector have not been extensively studied, thus creating a fundamental gap in our knowledge.This research aims to investigate recent environmental changes recorded in a salt marsh setting from the Nalón estuary (Asturias, N Spain). A comprehensive multidisciplinary approach (benthic foraminifera, pollen content, grain size, TOC, TN, trace metals and magnetic susceptibility), coupled with a robust chronology (210Pb, 137Cs, 239+240Pu), has been applied to a short sediment core drilled in the Junquera salt marsh, located in the middle estuary.This sedimentary record, which spans to the last ~150 years, reveals the dominance of fluvial processes in the Nalón estuary, with the occurrence of a strong flood in the mid-20th century. This extreme natural event, which disturbed previous environmental dynamics, can be stratigraphically constrained with distinctive micropaleontological and geochemical signatures. Subsequently, trace metals, magnetic susceptibility and pollen content show variable patterns consistent with the extensive mining activities and land-use modifications developed upstream.
Deciphering the formation processes of linear dune gullies on Mars
Authors: Roelofs Lonneke , Visschers Simone , Conway Susan , de Haas Tjalling , Kleinhans Maarten , Sylvest Matthew , Patel Manish
Published: March 2024

Linear dune gullies are a unique surface feature on Mars of which no Earth analogue exists. They have long and constrained channels, lack an alcove, and often end in circular depressions called pits. Satellite observations have shown that the activity of linear dune gullies is related to the presence of CO2 ice, which led to the hypothesis that these landforms are carved by blocks of CO2 ice. Here, we experimentally test this hypothesis under Martian atmospheric conditions and establish a better physical understanding of how this process works. We conducted >100 experiments under Martian atmosphere in which we released CO2-ice blocks on a sloping sand bed. Our experiments show that CO2-ice blocks move downslope by two different modes of transport, both driven by large gas fluxes produced by CO2-ice sublimation under Martian atmosphere. In general, on steep coarse-grained slopes, the blocks slide down, carving narrow and shallow elongated depressions. On gentle fine-grained slopes, the blocks burrow themselves into the sand and slowly carve deep elongated depressions with high and narrow levees, ending in circular pits. These two modes of transport of the CO2-ice blocks can explain the different morphologies of linear dune gullies on different locations, with some gullies having very defined levees and some not, as well as the transition in morphology of certain linear dune gullies from steep upper slopes to gentle lower slopes that we observe on Mars. These experiments allow us to reconstruct how linear dune gullies formed based on their morphology, and infer the necessary climatic and topographic conditions allowing these gullies to form: 1) CO2 ice needs to be preserved at the top of the dune until the beginning of spring, 2) the rest of the dune needs to defrost and heat up to induce sublimation of the CO2 ice once it has started to move downslope, and 3) the dunes need to be made of material that is fine enough to be propelled away from the block and form levees. The first two conditions should limit the formation of linear gullies to south-facing concave slopes at the beginning of spring, which is also where and when activity in these gullies is observed.
 Three-dimensional modeling of the O2(1Δ) dayglow  and implications for ozone in the middle atmosphere.
Authors: Diouf Mouhamadou , Lefevre Franck , Hauchecorne Alain , Bertaux jean-loup
Published: March 2024

Future space missions dedicated to measuring CO2 on a global scale can make advantageous use of the O2 band at 1.27 µm to retrieve the air column. The 1.27 µm band is close to the CO2 absorption bands at 1.6 and 2.0 µm, which allows a better transfer of the aerosol properties than with the usual O2 band at 0.76 µm. However, the 1.27 µm band is polluted by the spontaneous dayglow of the excited state O2(1Δ), which must be removed from the observed signal.We investigate here our quantitative understanding of the O2(1Δ) dayglow with a chemistry-transport model. We show that the previously reported -13% deficit in O2(1∆) dayglow calculated with the same model is essentially due a -20 to -30% ozone deficit between 45-60 km. We find that this ozone deficit is due to excessively high temperatures (+15 K) of the meteorological analyses used to drive the model in the mesosphere.The use of lower analyzed temperatures (ERA5), in better agreement with the observations, slows down the hydrogen-catalyzed and Chapman ozone loss cycles. This effect leads to an almost total elimination of the ozone and O2(1Δ) deficits in the lower mesosphere. Once integrated vertically to simulate a nadir measurement, the deficit in modeled O2(1Δ) brightness is reduced to -4±3%. This illustrates the need for accurate mesospheric temperatures for a priori estimations of the O2(1Δ) brightness in algorithms using the 1.27 µm band.
Dictionary learning for downward continuation of gravity data
Authors: Michel Volker , Schneider Naomi , Sneeuw Nico
Published: March 2024

A multitude of basis functions is available for modelling the gravitational field based on satellite data. The Regularized Functional Matching Pursuit (RFMP) algorithm, which has been developed by the Geomathematics Group Siegen, proved to be able to combine different sets of such trial functions. For this purpose, a dictionary is built as a redundant union of different established basis systems (such as spherical harmonics, radial basis functions and Slepian functions). In an iterative scheme, a best basis is selected by minimizing a Tikhonov-Phillips functional. In a recent add-on (the LRFMP), the dictionary does not have to be discretely predefined but can be learned as part of the algorithm. This is implemented as a non-linear optimization problem. The LRFMP has several benefits, which will be demonstrated in the presentation, where we show numerical tests regarding the inversion of noisy gravity data on real satellite orbits.References:N. Schneider, V. Michel and N. Sneeuw, High-dimensional experiments for the downward continuation using the LRFMP algorithm, preprint available at http://arxiv.org/abs/2308.04167, 2023.N. Schneider, V. Michel: A dictionary learning add-on for spherical downward continuation, Journal of Geodesy, 96 (2022), article 21 (22pp). Source Code:N. Schneider, (L)IPMP source code for gravitational field modelling, v2-dc-2023. Zenodo. https://doi.org/10.5281/zenodo.8223771, 2023.  
From Iran to Iberia: character and evolution of sunken groundwater-harvesting agroecosystems in aeolian sand since Early Islamic times until today
Authors: Roskin Joel , Robins Lotem , Sanchez Ruben , Ostrowski Adam , Bookman Revital , Taxel Itamar
Published: March 2024

By compiling and reviewing data on traditional sunken groundwater-harvesting agroecosystems in aeolian sand (SGHAS) in Iran, Egypt, Gaza Strip, Algeria and Iberia we analyze the motivation, function, crop-type and abandonment of recently excavated Early Islamic- to early Crusader-period (late 9th-mid-12th century) Plot-and-Berm (P&B) agroecosystems situated along the Mediterranean coast of Israel. The SGHAS and the Early Islamic P&B agroecosystems were affiliated with nearby towns. The SGHAS enrichened the sandy substrate with local organic material, while the Early Islamic sites used local urban refuse. The extensive long-term investment in earthworks to form SGHASs was proven profitable due to prime water security in the form of continuous shallow, ~0.6-2  m deep groundwater availability coupled with rainfall for agriculture and groundwater replenishment. The SGHAS crops are mainly a wide range of vegetable types, watermelons, date palms, and grapes.The spotty appearance of SGHAS temporally lags after the abandonment of the Early Islamic P&B agroecosystems. They appear to have independently developed since the 15th-16th century until the 19th-early 20th century. These late/post-medieval to early modern times are characterized by an unprecedented growth in the variety of food and textile crop types due to the introduction of species from arid Muslim-controlled regions and from the newly discovered Americas. This convergence exemplifies the appearance of local ingenuities derived from growing agricultural and technological knowledge and experience, crop variety and pressing needs for capital and food security. Such engineering agriculture demonstrates entrepreneurship usually supported by local administrations.Our finds do not support a successive spatial-temporal dissemination process since Early Islamic times as occurred for qanats in western Asia, Arabia, North Africa and Iberia. The Early Islamic agroecosystems were significantly ahead of their time, possibly explaining why they were never reestablished following their abandonment. This understanding implies that the Early Islamic crops were probably partly different from those of the later SGHAS counterparts and maybe also provided inedible, profitable crops like cotton. This study demonstrates the importance of traditional analogues for interpreting archaeological research gaps of past agricultural engineering landscapes and provides a focal point for reestablishing traditionally-based, community, and sustainable agricultures.
Drivers of Global Marine Heatwaves in a Warming World
Authors: Bian Ce , Jing Zhao , Wu Lixin
Published: March 2024

Global warming has exacerbated occurrence of extreme events, threatening the environment of human living. Marine heatwaves (MHWs) are prolonged extreme warm water events in the ocean, exerting devastating impacts on marine ecosystems. Comprehensive knowledge of physical processes controlling MHW life cycles is pivotal to improving MHW forecast capacity, yet it is still lacking. Here, we use a historical simulation from a global eddy-resolving climate model with an improved representation of MHWs, and innovatively show that heat flux convergence by oceanic mesoscale eddies acts as a dominant driver of MHW life cycles over most parts of the global ocean. In particular, the mesoscale eddies make an important contribution to growth and decay of MHWs, whose characteristic spatial scale is comparable or even larger than that of mesoscale eddies. Moreover, our results proved that features of global MHWs are scale-dependent. The primary drivers of MHWs shift from oceanic advection to atmospheric forcing as their spatial scale becomes larger. There is evident geographic heterogeneity in the transition scale between these oceanic and atmospheric-process dominated regimes. Our study reveals the crucial role of mesoscale eddies in controlling the global MHW life cycles and highlights that using eddy-resolving ocean models is essential for accurate MHW forecasts. Another contribution is we clarified the transition scale of global MHWs, which is essential for parameterization of MHWs forecasting in a warmer future. 
Geological modelling and reservoir simulation workflows for hydrogen geostorage in depleted gas fields, Aotearoa New Zealand
Authors: Parker Matt , Dempsey David , Liu Jinjiang , Nicol Andy
Published: March 2024

Underground storage of green hydrogen in depleted gas fields could provide Aotearoa New Zealand (ANZ) with a storage option critical for meeting peak energy demands and realising green hydrogen ambitions. During early de-risking of specific sites, it is important to develop an accurate geological model to test whether the reservoir has the desired containment, volume and hydrogen deliverability. However, where seismic reflection lines and well data are limited and/or the storage system is structurally complex, the resulting geological models may be non-unique. Therefore, injection and withdrawal simulations using different structural end members is critical to constrain how a hydrogen plume may flow within (and out of) the container and interact with existing reservoir fluids.Here we present workflows for modelling a multi-year injection and withdrawal cycle of hydrogen into a depleted gas field. We use data from the Tariki Sandstone Member of the Ahuroa field in the Taranaki Basin, currently used to store natural gas in ANZ. This reservoir is located 2 km deep at the crest of an anticline above a major thrust fault, with marine mudstones forming the top seal and low-permeability fault rock the lateral seal. With only mixed quality 2D seismic reflection lines and a tight well cluster, the precise geometry of the thrust fault and its relations to smaller secondary faults is poorly constrained.To capture this uncertainty in our simulations, we have developed two 3D geological models of the Ahuroa field in Leapfrog Energy software. We use these geological models to conduct dynamic simulation of hydrogen injection and withdrawal using the massively-parallel simulator PFLOTRAN-OGS. We develop simulations that allow us to, over a 10-year cycle, test for closure or spill into adjacent fields, and predict the amount of mixing with remnant natural gas and formation water. During the simulations, we see major differences between the two geological models related to cushion injection and working H2 volumes, rates of water production and impurities due to natural gas. Additionally, one model has high risks of unrecoverable H2 gas loss when over-pressurised. Finally, we reimport the results back into Leapfrog for visualisation of the behaviour of the two hydrogen plumes over time.
Repeated failures of the giant Beshkiol landslide and its impact on the long-term Naryn Basin flooding, Kyrgyz Tien Shan
Authors: julie losen , magali rizza , alexis nutz , maxime henriquet , mathieu schuster , erkin Rakhmedinov , sultan Baikulov , kanatbek Abdrakhmatov , jules fleury , vincent Rinterknecht , lionel siame
Published: March 2024

Earthquake-triggered landslides pose significant hazards and their long-term effects can radically reshape the local physiography but also may generate cascading risks. Indeed, a landslide could dam the river, having for consequence the formation of an upstream lake, which in turn makes the dam unstable, leading to cataclysmic flooding in the case of sudden failure. The Naryn River is one of the most important rivers in the Western Tien Shan, and major changes in its dynamics could have a significant economic impact in Central Asia and lead to political tensions over water management. Our study focuses on the Beshkiol paleo-landslide (>10km3), one of the largest in Central Asia, an overlooked hazard along the Naryn River.Through a multi-disciplinary approach that combines detailed geomorphological, sedimentological and chronological (luminescence, cosmogenic and radiocarbon) analysis over a study area more than 130 km-long, we determined the different phases that affected the evolution of this landslide from the late Pleistocene to the late Holocene. First of all, two lacustrine sequences have been identified in the Naryn Basin, illustrating two successive periods of river damming and a lake outburst flooding. The triggering of the Beshkiol landslide occurred ~52 ka ago, led to the damming of the Naryn River and the formation of an 80 km-long lake upstream. Our chronological constraints highlight a residence time of 36,000 years, one of the longest ever documented in the world for a natural dammed-lake. This lake then drained in a cataclysmic event around 15 ka, which most likely led to the flash flooding of the downstream basin of the Naryn River (Kazarman Basin), as evidenced by very high energy deposits identified upstream of the landslide. However, shortly afterwards (less than 1,500 years), the foot of landslide was reactivated, causing the formation of a second lake, with a residence time estimated at ~7,600 years. This period was followed by a gradual emptying, and a phase of erosion that shaped the present landscape. Our results highlight that cascading events took place over the last 50,000 years and show complex interactions between the Naryn River and the largest landslide in Central Asia. Today, this landslide is categorized as inactive, but in view of the large volumes of material that can be reactivated by earthquakes or changes in precipitation, it is necessary to take this hazard into account as several thousand people living in the region could be impacted
Study of the Decadal Predictability of Mediterranean Sea Surface Temperature Based on Observations
Authors: Yan Xiaoqin , Tang Youmin , Yang Dejian
Published: March 2024

Sea surface temperature (SST) changes in the Mediterranean Sea have profound impacts on both the Mediterranean regions and remote areas. Previous studies show that the Mediterranean SST has significant decadal variability that is comparable with the Atlantic multidecadal variability (AMV). However, few studies have discussed the characteristics and sources of the decadal predictability of Mediterranean SST based on observations. Here for the first time we use observational datasets to reveal that the decadal predictability of Mediterranean SST is contributed by both external forcings and internal variability for both annual and seasonal means, except that the decadal predictability of the winter mean SST in the eastern Mediterranean is mostly contributed by only internal variability. Besides, the persistence of the Mediterranean SST is quite significant even in contrast with that in the subpolar North Atlantic, which is widely regarded to have the most predictable surface temperature on the decadal time scale. After the impacts of external forcings are removed, the average prediction time of internally generated Mediterranean SST variations is more than 10 years and closely associated with the multidecadal variability of the Mediterranean SST that is closely related to the accumulated North Atlantic Oscillation forcing.
Plio-Pleistocene Southern Ocean Paleoceanography: Latitudinal drilling in the Southwestern Indian sector of the Southern Ocean
Authors: Ikehara Minoru , Crosta Xavier , Jaccard Samuel , Naish Tim , Nakamura Yasuyuki
Published: March 2024

Proposal 918-pre in the Southern Ocean exists in the current science evaluation system of IODP. Site surveys were completed in 2019. We would like to develop an international research project based on this proposal by conducting new drilling/coring in the IODP3. First, we would like to drill by riserless drilling vessel, but if drilling is not feasible, we plan to consider giant piston coring as an option. The Southern Ocean (SO) is a key region that profoundly influences climate variability throughout the Cenozoic. Because the SO redistributes heat, fresh water, carbon, and nutrients around the global ocean it plays a key role in the climate system. The growth of ice sheets in the Antarctic continent and changes in sea ice in the surrounding ocean are important variables in Earth’s climate system. Upwelling of deep waters in the Antarctic Circumpolar Current (ACC), in particular, is a key process of the meridional overturning circulation (MOC) as it constitutes the return path for deeply-sequestered carbon and nutrients towards the surface and hence important in the partitioning of carbon between the ocean and the atmosphere. Furthermore, physical and biogeochemical processes modulate nutrient export through SO-sourced intermediate waters that ventilate 75% of the world’s thermocline, thus playing a vital role in influencing low-latitude productivity and ecosystems.The western Indian sector of the SO, located at the confluence of the SO overturning cells and the MOC return surface flow, is a key region to document the links/teleconnections between the SO, global ocean/atmospheric circulations and hence climate (Fig. 1). It provides a unique opportunity to obtain exceptionally high-resolution sediment records to document and unravel the interaction and feedbacks between atmosphere, ocean and cryosphere from millennial to orbital-timescales during the late Neogene and Quaternary, focus on past 6 Ma (Fig. 2).Specifically, the proposal aims to constrain further – (A) past changes in the upwelling and latitudinal position of the ACC; (B) the dynamic controls of circum-Antarctic deep ocean ventilation/overturning circulation; (C) their link to the global ocean circulation; (D) past changes in the sea ice coverage and dust inputs; and (E) their implications for the marine biogeochemical cycles of carbon and nutrients. The anticipated results will elucidate the evolution of the SO carbon cycle, identify potentially dominant physical and biogeochemical mechanisms of change, document past oceanic bipolar teleconnections with global MOC dynamics, and provide constraints on its future evolution in response to anthropogenic warming.Our scientific objectives relate to Strategic Objective 3 (Earth’s climate system), Strategic Objective 4 (Feedbacks in the Earth system), and Flagship Initiative 1 (Ground truthing future climate change) in the 2050 Science Framework.