bluuebunny/crossref_metadata_2025 huggingface dataset:
Observed Impacts of the Hunga Tonga Eruption on Stratospheric Temperature
Authors: Stocker Matthias , Steiner Andrea K. , Ladstädter Florian , Foelsche Ulrich , Randel William
Published: March 2024

The massive eruption of the Hunga Tonga-Hunga Ha'apai (HTHH) volcano in 2022 not only set a record for plume height, transporting aerosols and water vapor up to an altitude of more than 50 km into the mesosphere, it also resulted in a substantial stratospheric aerosol optical depth perturbation and previously unobserved hydration of the stratosphere. These disturbances are expected to persist for several years, affecting stratospheric circulation, composition, and dynamics.Our study investigates the stratospheric temperature signals of the HTHH eruption and their separation from the broader stratospheric variability. Using high-resolution satellite observations, we focus on the lower and middle stratosphere in the tropical and mid-latitudes for the period from January 2022 until June 2023. Within the early post eruption plume we find a pronounced temperature dipole structure that follows the vertical evolution of water vapor and aerosols. In addition, we find persistent long-lived cooling of up to -4 K in the middle tropical and subtropical stratosphere. The cooling pattern closely corresponds to the distribution of water vapor from the months post-eruption to mid-2023. We anticipate that this negative anomaly has implications for stratospheric circulation and composition, especially ozone levels.Our results provide new insights into the localized temperature changes shortly after the eruption and the short-term stratospheric climate signals. We are confident that our results will be useful for testing simulation results against observational analyses in future modeling studies.
High-frequency sea level temporal variability estimate from SWOT KaRIn and Sentinel-3A/B crossovers
Authors: Barnoud Anne , Fraudeau Robin , Lalau Noémie , Bouih Marie , Ablain Michaël , Raynal Matthias , Dibarboure Gérald , Boy François
Published: March 2024

The observation of sea level variability on very small time scales ranging from less than an hour to a few days is currently very limited with the constellation of nadir altimeter satellites. Calculating sea surface height at crossovers between a single mission or several nadir altimeter missions makes it possible to analyse the sea level variability on these very short timescales for a small number of measurements (a few hundred). Moreover, these observations are spatially sparsely distributed, most often at very high latitudes for crossovers of less than a few hours of time difference.Thanks to the launch of the joint CNES/NASA SWOT mission in December 2022 with swath measurements, a new paradigm for observing high-frequency temporal variability in sea level is now possible. SWOT KaRIn instrument offers 2D observations of the oceans with an unprecedented coverage and resolution. We take advantage of this new high quality dataset to estimate the sea level variability over short time scales. The crossovers of SWOT KaRIn during the 1-day orbit phase with itself and with Sentinel-3A/B nadir observations less than 1 hour to 72 hours of time difference from 17/04/2023 to 07/07/2023 are analysed. The crossovers with Sentinel-3A/B offer a very good spatial sampling of the oceans which cannot be reached with SWOT crossovers only. We analyse the variance of the sea surface height differences at the crossovers, as a function of time difference and of latitude. The variability of the sea surface height differences at the crossovers contains both the sea level variability and the instrumental errors. We attempt to disentangle the errors from the sea level variability. Sea surface height differences variance with time differences tending to 0 hours, hence free of oceanic variability, amount to ~3.2-3.5 cm. This value increases fastly with time difference up to about 4 hours as the contribution of sea level variability and errors increase. With time differences of 4 hours, the sea surface height differences variance reaches 4 cm. Then, the increase of the sea surface height differences variance slows down, as some phenomena are not correlated anymore, and roughly linearly increases to reach 5 cm for time differences of 72 hours.
From energy to soil organic matter
Authors: Kuzyakov Yakov , Wang Chaoqun , Gunina Anna
Published: March 2024

We developed a new concept of soil organic matter (SOM) formation and microbial utilization of organic carbon (C) and energy: microorganisms use most of the organics entering the soil as energy rather than as a C source, while SOM accumulates as a residual by-product because the microbial energy investment in its decomposition exceeds the energy gain. So, the energy use efficiency (EUE) is at least as important as the carbon use efficiency (CUE). The microbial EUE depends on the nominal oxidation state of carbon (NOSC) of organic compounds, which is the exact proxy of energy content: The energy content per C atom (enthalpy of combustion) increases by 108 kJ mol−1 C per one NOSC unit. The NOSC in litter remaining by decomposition decreases, and the energy content increases. Consequently, the NOSC of the remaining compounds drops to −0.3 units, and the oxidation decreases due to the residual accumulation of aromatic and aliphatic compounds, and entombment of the necromass. Preferential recycling of energy-rich reduced (lipids, aromatics, certain amino acids, amino sugars) and the microbial degradation of oxidized compounds (carboxylic acids) enrich energy content in remaining SOM. This explains why SOM is not fully mineralized (thermodynamically unfavorable). Energy from litter activates decomposers to mine nutrients stored in SOM (the main function of priming effects) because the nutrient content in SOM is 2–5 times higher than that of litter. Thus, the energy captured by photosynthesis is the main reason why microorganisms utilize organic matter, whereby SOM is merely a residual by-product of nutrient storage and a mediator of energy fluxes. For the first time we assessed the NOSC of microbial biomass in soil (−0.52) and calculated the corresponding energy content of −510 kJ mol−1 C, whereas bacteria contain less energy per unit of C than fungi. We linked CUE and EUE considering the NOSC of microbial biomass and element compositions of substrates utilized by microorganisms. The microbial EUE is always lower than CUE. This is one of the reasons why microbial growth is more limited by energy than by C. Based on the comparison of processes of C and energy utilization for cell growth and maintenance, we concluded that the two main mechanisms behind lower EUE versus CUE are: (i) microbial recycling: C can be microbially recycled, whereas energy is always utilized only once, and (ii) chemical reduction of organic and inorganic compounds: Energy is used for reduction, which is ongoing without C utilization.Gunina A, Kuzyakov Y 2022. From energy to (soil organic) matter. Global Change Biology 28 (7), 2169-2182Wang C, Kuzyakov Y 2023. Energy use efficiency of soil microorganisms: Driven by carbon recycling and reduction. Global Change Biology 29, 6170-6187
Development of the Isotope-enabled Fully Coupled Model MIROC6-iso
Authors: Li Yifan , Cauquoin Alexandre , Okazaki Atsushi , Yoshimura Kei
Published: March 2024

  Understanding Earth's climate is more important than ever, as it allows us to anticipate future changes and their potential impact on human society. The study of paleoclimate is crucial for understanding the mechanisms that have driven past climate variations, including natural oscillations, external forcings, and feedback processes within the Earth's climate system. Stable water isotopes (H218O and HD16O) can serve as tracers to analyze the origins of water vapor, precipitation, and cloud formation, thereby enhancing our understanding of evaporation, condensation, and precipitation processes.  In order to understand coupled dynamics process, such as such as atmospheric convection/cloud formation, land surface processes, and sea ice effects according isotope insight, we developed an isotope-enabled fully coupled model(atmosphere-land-ocean coupled model), MIROC6-iso.  MIROC6 is the newest version of the Model for Interdisciplinary Research on Climate (MIROC) series. MIROC6 has updated the physical parameterizations in all sub-modules and vertical resolution. The overall reproducibility of mean climate, internal climate variability, midlatitude atmospheric circulation and tropical climate systems in MIROC6 is better than that in MIROC5.  Based on the AGCM MIROC6-iso to which stable water isotopes are implemented into the atmosphere and land-surface component[1], we implemented the stable water isotopes into the ocean and sea-ice component at first. Then, we make the atmosphere, land-surface, ocean and sea-ice component coupled and enabled them to interacted with each other.  We performed the simulation under the preindustrial period (PI), corresponding to the climate conditions at 1850 CE. In the ocean component, we employed a spin-up process by separately running the ocean model COCO-iso from the  ocean component of the CGCM MIROC6-iso for 4000 years. This was done to establish initial conditions for the ocean part of CGCM MIROC6-iso, ensuring that the ocean component operates directly under equilibrium conditions. CGCM MIROC6-iso shows a good performance in simulating isotope ratios in precipitation. Additionally, we compared the d-excess of precipitation, as well as the isotopic delta values of the ocean surface and deep ocean. We also examined the relationship between the isotopic delta values and both temperature and sea surface salinity. CGCM MIROC6-iso may has many potential applications in climate analysis, such as analyzing the monsoon wind fields in monsoon cycles, as well as the coupled mechanisms of the atmosphere and ocean in ENSO, monsoon and so on. Then it can be used to analyse the climate of the past. We hope this new model could contribute to CMIP6/PMIP4.[1] Okazaki, A., Li, Y., Kino, K., Cauquoin, A., and Yoshimura, K., Evaluation of a newly developed isotope-enabled AGCM MIROC6-iso under the present climate, AGU 2023, San Francisco (USA), December 2023.
A new > 400 ka paleoenvironmental and paleoclimate record from Tenerife Island (Canary Archipelago)
Authors: Jambrina-Enríquez Margarita , Armenteros-Armenteros Ildefonso , Martín-Luis M. Candelaria , Casillas-Ruiz Ramón , Valero-Garcés Blas L.
Published: March 2024

Detailed reconstructions of Quaternary paleoclimate and paleoenviromental evolution of the Canary Islands have been hampered by the scarcity of long terrestrial records.  In this study, we present the results of a multiproxy approach based on sedimentological, geochemical, and magnetic susceptibility measurements in a > 40 m long new sediment cores retrieved from a paleolake located within the Vega Lagunera valley on La Laguna, Tenerife Island (Canary Archipelago). Vega Lagunera is a NE-SW oriented valley formed by fluvial erosion of the Miocene basalts of the Anaga massif and blocked by Late Pliocene and Pleistocene lavas emitted from the NE Dorsal Ridge. The 40 m long sequence represents the longest Quaternary terrestrial record in the Canary Islands. Preliminary sedimentation rates based on OSL dates in previous cores suggest a basal date of > 400 ka and a 9 m long Holocene record. The geochemical and magnetic susceptibility signatures identified a shallow lake with clastic alluvial influences during the Pleistocene, a rapid Holocene onset and dominant shallow lacustrine sedimentation since mid Holocene till drainage of the remnant lake in mid 19th century. The interplay of alluvial and lacustrine facies throughout the Holocene period and the geochemical evolution characterized the sedimentological processes linking lake and catchment dynamics, organic productivity, nutrient supply, and runoff. Age models are in progress to identify the glacial / interglacial evolution of these oceanic islands and the relative role of subtropical and mid latitude atmospheric and oceanic patterns.This research is conducted as a part of the CCR-CAN project (TED2021-129695A-I00) supported by MCIN/AEI /10.13039/501100011033 and NextGenerationEU/ PRTR.
Use of ensemble prediction systems in operational oil spill modelling
Authors: Nordam Tor , Nepstad Raymond , Litzler Emma , Dagestad Knut-Frode , Breivik Øyvind
Published: March 2024

Models play an important role in oil spill response and contingency planning. They are used ahead of time, to analyse possible scenarios and risks, and they are used during an active spill, to help direct response measures. Given the chaotic nature of both the ocean and the atmosphere, predictions are fundamentally challenging, particularly beyond a time window of a few days. To deal with this challenge, weather forecasters have over the last decade been moving towards ensemble prediction systems (EPS), rather than simply focusing on improved model resolution. The idea is that an ensemble of different, but (ideally) equally likely, predictions will provide useful information about the forecast uncertainty.Given that EPS weather forecast data is increasingly available, these should be routinely used in operational oil spill modelling. In this talk, we present numerical experiments of hypothetical oil spill scenarios off the coast of Norway, using the OSCAR oil spill model. For ocean input data, we use the operational NorKyst800 ROMS setup provided by MET Norway, and for wind we use the MetCoOp Ensemble Prediction System (MEPS), a collaborative product from the Meteorological institutes of Norway, Sweden and Finland. Due to operational availability, we use only a single realisation of the ocean model, but 30 different ensemble members for the atmosphere model. We investigate the potential for the combination of EPS wind data and deterministic current data to provide added value in a response situation, even though the ocean and atmosphere data will not always be dynamically consistent. Since wind, more than currents, drive stranding and entrainment of oil, the use of a wind ensemble will provide some information about the uncertainty in predictions of surface slick as well as locations and amounts of beached oil.Additionally, we compare the use of deterministic ocean data and EPS wind data with another setup, Barents 2.5 km, where we use a dynamically consistent set of EPS data for both the ocean and the atmosphere. We show that this latter setup has larger variation between ensemble members, indicating the potential added value for oil spill response in moving towards operational EPS forecasting also for ocean models.
Machine learning weather prediction model development for global ensemble forecasts at NCEP
Authors: Wang Jun , Tabas Sadegh , Yang Fanglin , Levit Jason , Stajner Ivanka , Montuoro Raffaele , Tallapragada Vijay , Gross Brian
Published: March 2024

Data driven machine learning-based weather prediction (MLWP) models have been under rapid development in recent years. These models leverage autoregressive neural network architectures and are trained using reanalysis data generated by operational centers, demonstrating proficient forecasting abilities. One remarkable advantage of these MLWP models is that, once trained, they take significantly less amount of computational resources to produce forecasts compared to traditional numerical weather prediction (NWP) models while maintaining or surpassing the NWP performance. NCEP has started machine learning development collaborating with the research community for several years.  This presentation will provide an overview of the development of MLWP models for the global ensemble forecast system at NCEP Environment Modeling Center (EMC). The model adopts state-of-the-art MLWP models such as GraphCast and leverages the methodologies from FuXi global ensemble system. The development includes developing cascade MLWP models, training the model with GEFSv12 reanalysis data and producing forecasts with the operational GEFSv12 initial states. The model will be validated using two years of GEFSv12 operational forecast data. The ultimate objective is to deliver 15-day forecasts with skill levels comparable to the operational GEFSv12.
The Deep Soil Ecotron – A Facility to Explore, Model, and Sense Deep Soil
Authors: Kayler Zachary , Strickland Michael , Williams David , Vargas Rodrigo , Tan Zeli , Gasch Caley , Crow Susan , Fierer Noah
Published: March 2024

The Deep Soil Ecotron will give researchers the unparalleled ability to investigate and experiment with deep soils while complementing established ecotrons across the globe. This facility, composed of twenty-four, highly instrumented ecounits, will allow for soil profiles up to three meters in depth to be repeatedly sampled and continuously monitored. This facility will be the first modern ecotron facility in the United States and as such will provide research infrastructure that this country currently lacks. The Deep Soil Ecotron will enable researchers to address the following four broad research needs using approaches and instrumentation that have been unattainable under more common field and laboratory experiments. First, the Deep Soil Ecotron will reveal how deep soil communities and processes affect and interact with surface soils to influence whole ecosystems. Second, the Deep Soil Ecotron will allow researchers to determine how deep soils and associated vegetation respond to global and land-use change, such as increasing soil temperature and agricultural management practices. Third, information gained from the Deep Soil Ecotron will be integrated into earth system models to improve model representation of soil carbon cycling. Fourth, the Deep Soil Ecotron will provide a testbed for the development of sensors for the in-situ monitoring of deep soils. This presentation will provide an overview of the Deep Soil Ecotron's design, capacity, and preliminary research agenda.
Subseasonal prediction of heatwaves in the Iberian Peninsula using causality-based transformer networks.
Authors: Decancq Cas , Hagan Daniel , Deman Victoria , Koppa Akash , Miralles Diego
Published: March 2024

Subseasonal prediction of heatwaves, although highly valuable for risk reduction, is challenging because heatwave onsets and propagation are complex processes with both fast and slow drivers from local to global scale. Traditionally, subseasonal forecasting relies heavily on dynamical model ensembles, which are complex and of high computational cost. As an alternative, machine learning provides potentially performant solutions that may match or even outperform these physical-based models. Transformers, in particular, are the current state-of-the-art deep learning infrastructures, and using multi-head-attention allows them to keep track of long-term complex dependencies in timeseries data. However, to better forecast heatwaves subseasonally, it is essential to move beyond purely predictor-to-target associative measures when identifying the sources of predictability. Such endeavours require causal frameworks that provide directionality and explainable power for the predictor-to-target relationships.This study seeks to implement the PCMCI+ (Runge, 2020) framework to identify causal drivers of heatwaves on the Iberian Peninsula on a subseasonal scale. Causally-selected predictors are employed to forecast the occurence of heatwaves up to six weeks in advance using transformer networks, both for different seasons and sub-regions in the Iberian Peninsula. Preliminary results reveal heatwaves can be predicted with reasonable accuracy with a forecast window of six weeks, particularly in water limited regions, using causality-based machine learning.Reference:Runge, J. (2020). Discovering contemporaneous and lagged causal relations in autocorrelated nonlinear time series datasets. In Conference on Uncertainty in Artificial Intelligence, pages 1388–1397. PMLR.
An ocean-atmosphere paradox, Phase 2
Authors: Durham Brian , Pfrang Christian
Published: March 2024

Last year we posed the question:  Given Earth’s ocean-atmosphere gas equilibrium, why do measured atmospheric carbon dioxide (CO2) curves rise more steeply against solvent temperature than predicted by Henry’s Law? (https://presentations.copernicus.org/EGU23/EGU23-6069_presentation.pdf). We here develop our experimental procedure to simulate more closely the ocean-atmosphere gas exchange in the lab, seeking to better understand the relationship between atmospheric CO2  and average sea surface temperatures, with implcations for past and future climate variability in the Earth System. To this end, we previously reported provisional trends when water and natural seawater samples are equilibrated with an atmospheric ratio of CO2 in air. We also outlined a narrower interest in the published offset in annual CO2 cycles between marine and terrestrial stations which record atmospheric CO2 levels (Ye Yaun et al 2019).Provisional results were compared with published values from seawater that had been `killed’ and acidified (Li and Tsui 1971 and Weiss (1974). Working at atmospheric partial pressures of CO2 however, a definitive value for the respective Henry constant was complicated by the difficulty of predicting an equilibrium asymptote in either water or seawater determinations.We therefore listed a number of modifications to be adopted in future campaigns to address this issue. One proposed modification was to investigate alternative catalysts. Sodium dodecyl sulphate (SDS) is therefore replaced with a natural enzyme complex, generically carbonic anhydrase (CA), described as efficient in the reversible hydration of CO2 to bicarbonate.  CA is seen as an enzyme family with several independent evolutions across the phylogenetic tree, abundant in plants, diatoms, eubacteria and archaea (Supuran, 2016). The metallo-proteins are described as including a reaction space that combines one half hydrophilic and the opposing half hydrophobic, `allowing these enzymes to act as some of the most effective catalysts known in nature’.In Phase 2 we therefore compare water samples with and without dosing with an infusion of terrestrial soil biota, while for seawater, being a living medium, we use a freshly-unfrozen sample of UK Atlantic coast water for each determination.
IODP Expedition 398 Reveals a Major Normal Fault along the Kolumbo Volcanic Chain
Authors: Preine Jonas , Hübscher Christian , Metcalfe Abigail , Pank Katharina , Woodhouse Adam , Koukousioura Olga , Chiyonobu Shun , Druitt Timothy , Kutterolf Steffen , Nomikou Paraskevi , Ronge Thomas , Beehte Sarah , Manga Miachel , McInsoth Iona , Tominga Masako , Crutchley Gareth , Karstens Jens ,   IODP Expedition 398 Scientists
Published: March 2024

 Many hazardous volcanic systems worldwide are located in extensional back-arc systems, where the crust is influenced by pervasive faulting. However, our knowledge about the spatial and temporal relationship between crustal faults and the emplacement of volcanic edifices is immature. Located on the South Aegean Volcanic Arc, the Christiana-Santorini-Kolumbo volcanic field formed in a continental rift zone and represents an ideal natural laboratory to study the structural interaction between volcanism and tectonism. From December 2022 to February 2023, IODP Expedition 398 drilled 12 sites across the volcanic rift system. We will present the results of core-seismic integration of several sites from the rift basins. Two of these drill sites lie on the hanging wall and footwall of the Kolumbo Fault, respectively. This fault strikes parallel to the Kolumbo Volcanic Chain and was previously considered a fault with little vertical offset. However, tephra and biostratigraphic markers identified in recovered cores from IODP Expedition 398 indicate a major vertical offset of >200 m (~260 ms TWT) along this fault. Seismic data reveal that this fault is a major NE-SW-directed normal fault and represents an important structural element of the rift system but subsequent rapid sedimentation of volcanoclastic material buried this fault. The volcanic edifices of the Kolumbo Volcanic Chain formed on the hanging wall of this fault at a distance of approx. 6 km from the surface trace. Adjacent, non-volcanic rift basins show pervasive internal fault zones at a similar distance from the respective basin-bounding faults, indicating that these faults may be the preferred pathway for magma to reach the surface. Our study implies a fundamental tectonic control of the emplacement of volcanoes at the Christiana-Santorini-Kolumbo volcanic field, a process that might be present at other back-arc systems.
Radiation budget at the Baltic Sea surface in 2010 – 2023 from SatBałtyk System
Authors: Zapadka Tomasz , Ostrowska Mirosława , Stoltmann Damian , Paszkuta Marcin
Published: March 2024

Global climate change, which causes, among other things, an accumulation of energy in the oceans, may cause irreversible changes to their ecosystems. This can be particularly quickly apparent in bodies of water that are shallow and small in relation to the Oceans, such as the Baltic Sea. In the SatBałtyk System (http://www.satbaltyk.pl), which aims to observe the state of the Baltic Sea environment based on satellite data, maps of the distributions of values of a number of physical biological and chemical parameters of the sea are collected and made available. Within the framework of this System, the SBRB (SatBałtyk Radiation Budget) model was launched, determining data on radiation budget (NET) at the sea surface. Daily maps of the spatial distribution of the radiation budget  and its components at the Baltic Sea surface are created based on data from SEVIRI, AVHRR, MODIS, SBUV/2, TOVS radiometers, and forecast auxiliary models. The component algorithms of this model were developed and validated against empirical data measured directly in the Baltic Sea (Zapadka et al. 2020). The uncertainties in the estimation of the radiation budget for the monthly averages are: RMSD 4 Wm-2 and BIAS -0.5 Wm-2. The individual downward and upward shortwave radiation fluxes are determined with an accuracy of RMSD 3 Wm-2, 1 Wm-2, BIAS 3 Wm-2, 0.1 Wm-2 respectively, and downward and upward longwave radiation fluxes are RMSD 4.5 Wm-2, 3.7 Wm-2, BIAS -0.8 Wm-2, 2.6 Wm-2 respectively. The uniform methodology used since 2010 has enabled an analysis of the variability of the radiation budget and its components at the surface of the Baltic Sea covering 14 years. Despite the natural variation in NET values and its components year-on-year, the analyses showed an annual growth trend of c. 0.7 Wm-2. Interestingly, the increasing trend applies to all NET components. An analysis of the possible causes of the trend observed in recent years may confirm the role of the anthropological factor in these changes.
Organic Carbon Degradation and Preservation in a Drained and Reflooded Peat Soil 
Authors: Sapir Guy , Angert Alon , Oved Rosenberg Yoav , Golen Rotem
Published: March 2024

Peatlands cover about 3% of the earth's land surface and store ~650 Pg of carbon in organic matter (OM), about 20% of the total global soil carbon stock. Unfortunately, these carbon stocks are largely at risk as many have been exploited intensively by humans since the Industrial Revolution. The most common reason for peatland deterioration is land reclamation for agricultural purposes which led to a massive global peat draining. The drainage of the Hula Marsh in Israel, in 1957, caused soil fires, enhanced erosion, subsidence, and nutrient enrichment of the downflow water system. This led to the decision to reflood part of the area in 1994 and to keep the groundwater level in surrounding cropland at roughly ~ 0.8 to 1.4 m below the surface. As a result, the Hula Marsh has peat sections that were drained for ~37 years before reflooding, while other sections are still drained for more than ~ 66 years. Hence, the Hula Marsh allows us to study the aerobic degradation of organic matter following drainage, and its preservation following reflooding. Five sediment cores (4 m long) were excavated from cropland over the historic marsh area at different discrete locations. Using RockEval-7 (RE7) analyses and soil aerobic respiration experiments, we have evaluated the organic matter of the drained, re-flooded, and saturated sections of the soil profile. Our findings show that in the upper, drained peat section, total organic carbon (TOC) is the lowest and the OM resistivity index (R-index) is the highest, inversely to the saturated section. The reflooded section values are a transition between these two sections. Both trends align with the expected oxidation and mineralization of the upper peat section and correlate to the water table history in all the soil profiles. The reflooded section experienced mineralization in the past, which presumably was lessened under the newly saturated conditions. Preliminary respiration experiment results indicate that the reflooded section has the highest decomposition rates and is more prone to decomposition. However, the drained and saturated sections have lower and similar respiration rates (per gram carbon) despite the differences in their OM characteristics.Further study will focus on respiration rates in all cores and the OM characterization in the drained and reflooded sections.
Dynamics of Coastal Extremes: Unravelling Estuarine Processes through Numerical Modelling
Authors: Furnish Aaron , Robins Peter , Neill Simon
Published: March 2024

Exploring the intricate relationships between land and marine processes is essential for a comprehensive understanding of climate dynamics. While contemporary coupled climate models have made significant progress in capturing various interactions, the explicit resolution of estuarine and intertidal processes remains a challenge. Building upon the foundation laid by the UKC3 UK national climate model, we present a novel perspective by incorporating a high-resolution (
A physically-based fractal model for predicting the electrical conductivity in partially saturated frozen porous media
Authors: Luo Haoliang , Jougnot Damien , Jost Anne , Mendieta Aida , Thanh Luong Duy
Published: March 2024

Macro-scale transport properties (e.g., electrical conductivity, effective excess charge density and hydraulic conductivity) can be conceptualized as capillary bundle models, in which the pore structure of porous medium is viewed as a bundle of capillary tubes of varying sizes. This approach can be used to understand and address the relationship between the petrophysical properties and the geometry of soil phases. When the temperature of porous medium decreases below the freezing temperature, the soil physical properties (transport properties) change drastically. This is attributed to the complexity of the heterogeneous formation of ice in the porous medium. Therefore, understanding better pore ice formation from microscale insights is crucial to describe the evolution of electrical conductivity with temperature in frozen porous medium. In this study, we consider that capillary radius and tortuous length follow fractal distributions, and that total conductance at the microscale scale is determined by the Gibbs-Thomson and Young-Laplace effects as well as by the surface complexation model. A new capillary bundle model is then proposed using an upscaling procedure, which considers the effects of both bulk and surface conductions. Based primarily on an electrical resistance apparatus and the NMR method, a series of laboratory experiments are carried out to study the influence of initial water saturation and salinity on electrical conductivity under unfrozen and frozen conditions. Additionally, the rationality and validity of the proposed model were successfully verified with published data in the literature and experimental data of this study. Our new physically-based model for electrical conductivity opens up new possibilities to interpret electrical and electromagnetic monitoring to easily infer changes in key variables such as liquid water content and moisture gradients.
Spatio-temporal evolution and scaling laws analysis of the recent three strongest earthquakes in the Ionian Sea region during the period 2014-2019.
Authors: Pavlou Kyriaki , Vallianatos Filippos , Michas Georgios
Published: March 2024

Our research aims to investigate the three recent and powerful earthquakes in the Ionian Sea region which occurred on January 26, 2014, November 17, 2015, and October 25, 2018, of magnitude Mw 6.1, Mw 6.0, and Mw 6.6 respectively using the complexity theory and the non-extensive statistical physics (NESP).The scaling properties that have been observed in the three aftershock sequences of the recent strong earthquakes that took place in the region of Ionian islands are presented. To analyze the evolution of three aftershock sequences, we plotted the cumulative number of aftershocks N(t) over time. Additionally, we used a modified version of Omori's law to study the temporal decay of aftershock activity.Based on non-extensive statistical physics, the analysis of interevent times distribution suggests that the system is in an anomalous equilibrium, with a crossover from anomalous (q>1) to normal (q=1) statistical mechanics for large interevent times. The obtained values of q indicate that the system has either one or two degrees of freedom. Furthermore, the migration of aftershock zones can be scaled as a function of the logarithm of time. This scaling is discussed in terms of rate-strengthening rheology, which governs the evolution of the afterslip process.AcknowledgementsThe present study is co-funded by the Special Account for Research Grants (S.A.R.G.) of the National and Kapodistrian University of Athens.
Biological connectivity indicates hydrological flow pathways in the subsurface
Authors: Schadewell Yvonne , Köhler Sören , Chifflard Peter , Leese Florian
Published: March 2024

Extreme rainfall events are likely to increase in intensity and frequency due to climatic changes and therefore the forecast of flooding events will become more important in the following decades. The flow properties of rainwater in the subsurface play a critical role in the flood formation process, but the underlying mechanism of this subsurface stormflow (SSF) formation has not been fully understood so far. Here, we explore the viability of environmental DNA (eDNA) as an indicator for small-scale flow pathway reconstruction. eDNA comprises genetic signatures from organisms across the Tree of Life (ToL), from whole microorganisms to molecular traces of higher taxa, such as plants or animals. The degree of similarity of biodiversity patterns indicates biological and therefore, in principle, also hydrological connectivity. As part of the SSF Research Unit we characterised 3 trenched hillslopes in 4 catchment areas in Germany and Austria through eDNA ToL-metabarcoding. With this broad-range approach, we aim to understand whether and how eDNA diversity patterns can inform subsurface flow pathways. We found three-dimensional connectivity patterns of biodiversity indicating systematic barriers as well as pathways of hydrological connectivity within each hillslope. Variation between catchments reflects their geographic differences as well as geological peculiarities. Although our results support the potential of eDNA to identify flow pathways and enhance our understanding of SSF, we are still at the beginning of understanding the viability of eDNA as a tracer in hydrological research. Nonetheless, making use of such natural occurring tracers can extend our understanding of hydrological phenomena and can contribute to a more accurate flood prediction.
Digging into the Future: The transition between bedrock and soil as an underexplored frontier zone in geoscience
Authors: Evans Daniel
Published: March 2024

Terrestrial environments and their ecosystems demand healthy, sustainable, and resilient soils. Over the past couple of decades, significant efforts have been made to safeguard global soils, yet the materials and resources responsible for soil formation have been widely overlooked.  The transition from bedrock to soil – a zone often described as ‘soil parent material’ – holds an exciting yet untapped potential for helping us address some of the largest environmental challenges, including climate change and the biodiversity crisis. In this award lecture, I will present a strand of my research programme ‘Building Tomorrow’s Soils’ which seeks to establish how soil parent materials enhance the sustainability, health, and resilience of soil systems. First, with a focus on carbon sequestration, I will highlight how the bedrock–soil transition zone has the potential to be a long-term store of organic carbon. I will then present research which shows that some soil parent materials release petrogenic (i.e. rock-derived) organic carbon into soils. These understudied inputs of organic carbon to soils are currently absent from most, if not all, soil carbon models, which threatens our ability to optimize soil carbon management in the long-term. Finally, I will argue that developing a mechanistic understanding about this transition zone – this underexplored material which is neither rock nor soil in structure and function, but a blend of both – requires a similarly cross-disciplinary approach.
New reconstruction of energetic electron precipitation and atmospheric ionization for 1844-2023 using deep learning networks
Authors: Asikainen Timo , Putaala Henna-Riikka
Published: March 2024

Reconstructions of energetic electron precipitation (EEP) and the atmospheric ionization it produces are important for state-of-the-art chemistry-climate models, which aim to model the climate impacts of EEP. The current version of the Coupled Model Inter-comparison Project, CMIP6, includes a reconstruction of EEP-induced ionization based on a parameterization dependent on geomagnetic Ap index. This reconstruction has been used in several climate studies over the past years. However, recent investigations have shown that the CMIP6 reconstruction underestimates the level of precipitation. Therefore, the atmospheric/climate impacts of EEP might be underestimated as well.To address this issue we introduce here a new reconstruction of EEP and the ionization it produces. This reconstruction is based on a new composite of energetic electron measurements from POES satellites which have been corrected for various instrumental and sampling effects. A theoretically motivated form of a pitch angle distribution consistent with pitch angle diffusion is fitted to these data to obtain a more realistic estimate of electron precipitation into the atmosphere.For the reconstruction we developed a deep learning network, which ingests geomagnetic aa and Dxt indices, sunspot number as well as seasonal variations and solar cycle phase. The network gives as output the daily latitude distributions of precipitating electron fluxes in three energy channels, which is then used to calculate the precipitating electron energy spectrum and associated atmospheric ionization from year 1844 to present.Here we present the main aspects of this new reconstruction and also compare it with the earlier CMIP6 reconstruction.
Evaluation of Copernicus and SMAP soil moisture products in an almond orchard in southeastern Spain
Authors: Sánchez Juan Manuel , Walker Elisabet , Sánchez-Virosta Álvaro , Calera Alfonso
Published: March 2024

Soil moisture (SM) plays an important role in the interactions between the atmosphere and the land surface, and has been widely recognized as a key variable of the climate system. Over the last decades, several global satellite products have been generated to monitor SM at different spatial and temporal resolutions. To use these products it is important to validate them with in-situ observations. In this study, the performance of the Soil Water Index (SWI) and Surface Soil Moisture (SSM) Copernicus’s products and the Soil Moisture Active Passive (SMAP) SMAP L3_SM_P_E product was evaluated over an irrigated almond orchard located in the semiarid area of Tarazona de la Mancha, Spain (39.2660N, -1.9397W). The almond trees were planted in 2017 in a homogeneous field of about 10-ha. The Copernicus SSM and SWI products at 1-km spatial resolution provide daily SM images covering Europe since 2015. The SSM is retrieved from the Sentinel-1 radar backscattering and SWI combines Sentinel-1 and Metop ASCAT data. The Level-3 SMAP product provides SM data every 2-3 days retrieved by the SMAP radiometer. SMAP L3_SM_P_E has a spatial resolution of 9 km. Here, the moisture content in the topsoil (5 cm) estimated by the satellite products was evaluated against observed SM measurements for the 2019-2023 period. Even though the field sensor registers SM data at different depths (10-120 cm), the SM observations of the first 10 cm were used to analyze the remote sensing products. The accuracy of the products was defined using the following statistics; the determination coefficient (R2), the root mean square difference (RMSD), bias, and the unbiased root mean square difference (ubRMSD). The results obtained show that in general, the evaluated products capture the temporal variability of the SM measurements. For SSM and SMAP differences against in-situ data resulted in RMSD of about 4.34 vol% and 4.85 vol%, respectively. Also, SMAP overestimates the observed data with a considerable bias of 3.60 vol%. These deviations could be due to the coarse spatial resolution, however, it achieves the highest correlation (R2=0.64). SSM shows a good agreement with in-situ measurements, yielding the lowest bias (bias=0.10 vol%), but poorer R2 than the other evaluated datasets (R2=0.22). The SWI product (RMSD=3.79 vol%, ubRMSD=3.73 vol%, R2=0.36, and bias=0.66 vol%) performs the best compared to SMAP and SSM. These results obtained in almonds are comparable to validation results published for other regions and land covers. Therefore, it is possible to indicate that satellite SM data and, specifically the SWI product could benefit the local water resources management.
Projected extreme oligotrophication of the marine ecosystems of the Adriatic Sea
Authors: Mentaschi Lorenzo , Lovato Tomas , Butenschön Momme , Alessandri Jacopo , Aragao Leonardo , Verri Giorgia , Guerra Roberta , Coppini Giovanni , Pinardi Nadia
Published: March 2024

The Adriatic Sea is home to diverse marine ecosystems, showing rich biodiversity and distinctive ecological dynamics. Its complex coastal habitats and waters support a variety of species, playing a crucial role in the region's ecology and economy. Understanding the impact of ongoing climate changes on this delicate environment is vital for the basin's future preservation. To address this, we developed a comprehensive biogeochemical model for the entire basin, featuring a horizontal resolution of approximately 2 km and 120 vertical levels. This model is driven by atmospheric, hydrological, and ocean circulation projections from 1992 to 2050, downscaled from one Med-CORDEX model under the RCP8.5 emission scenario, developed within the AdriaClim project. The projected changes between 1992-2011 and 2031-2050 were evaluated in distinct trophic ecoregions identified by means of a k-medoid classification. The results reveal a strong oligotrophication tendency, particularly pronounced in the northern estuarine area. This trend can be largely attributed to a significant decrease in river discharge projected by our modelling system for the rivers of the Po Plain. This scenario of unproductive resources, ongoing warming, salinization, and acidification poses concerns about the long-term resilience of the Northern Adriatic food web structure, adapted to thrive in high trophic conditions. Our study provides the stakeholders with insights into how potential long-term decreases in Northern Adriatic river regimes might impact the marine ecosystem and its future goods and services.
Investigating the path dependence of climate changes in a 200-member ensemble of overshoot scenarios
Authors: Dickau Mitchell , Matthews H. Damon
Published: March 2024

Current policies have global mean temperature (GMT) on track to surpass the temperature thresholds agreed upon in the Paris Agreement. Therefore, if the goals of the Paris Agreement are to be met, there is an increasing likelihood of temporarily overshooting the 1.5°C or well-below 2.0°C thresholds. Using an intermediate complexity global Earth system model, we explore the climate implications of temperature overshoot using ≈100 pairs of multi-gas emissions scenarios from the ENGAGE project, with peak temperatures from ≈1.5°C to ≈2.2°C. For each pair of scenarios, the first is constrained by the remaining carbon budget (RCB) in 2100, which allows for the possibility of overshoot, while the second is constrained by the same RCB irrespective of a time horizon and acts as a baseline scenario. The comparisons of the pairs of scenarios demonstrate that the climate changes that occur at a given GMT are path dependent. In this presentation, we show how the impacts of overshoot vary depending on: 1) peak temperature, 2) the degree of overshoot, 3) the duration of overshoot, and 4) the amount of warming caused by CO2 vs. non-CO2 emissions. Our study expands on the literature by investigating the climate implications of temperature overshoot in an ensemble of ≈200 multi-gas scenarios with a range of temperature targets using a spatially explicit Earth system model.
A new planning strategy for integrating surface water and groundwater management to face climate change impacts in the Dar Es Salaam Plain, Tanzania (Africa).
Authors: De Filippi Francesco Maria , Sappa Giuseppe
Published: March 2024

Groundwater is considered worldwide an important and resilient reserve of freshwater for human needs. The increasing demand, combined with climate change impacts, is leading to a remarkable quali-quantitative decay of water resource, especially in many megacities of the Global South, where the rapid urban growing pushed to environmental critical issues as the case of seawater intrusion for coastal aquifers. At the same time, the uncontrolled urbanization without a territorial planning favors the runoff and places ever greater areas in hydraulic danger, increasing the risk of flooding in currently inhabited areas. Dar es Salaam, in Sub-Saharan Africa, is one of these cases: a city of more than 4 million of inhabitants, with a population growth rate of about 5 per cent per year. A high dependence on natural resources ecosystems is mainly due to hybrid rural-urban livelihoods. The urban pressure on the aquifer caused a serious threat on water quality and quantity due to saline intrusion along the coastline, with depletion of groundwater levels and contamination of pumping wells. Moreover, the increasing risk of water scarcity and flooding due to climate change is threatening the local community, with an increasing need for adaptation measures. Catchment imperviousness of Mbezi River basin increased by 41% (2003-16), causing floods, erosion, land and marine pollution.A new vision needs to integrate the groundwater management strategies, already proposed in the context of the “Adapting to Climate Change in Coastal Dar es Salaam” (ACC-DAR) project, with surface water management too. Aim of this feasibility study is to outline a strategy for a sustainable water management in the Dar Es Salaam territory, through the planning of MAR (Managed Aquifer Recharge) solutions in specific areas. This approach could be helpful to solve or, at least, mitigate the impact of both flooding and groundwater overexploitation in the area, allowing to support stakeholders and public government in implementing local policies and proposing a more sustainable use of the resource. 