bluuebunny/crossref_metadata_2025 huggingface dataset:
Near-real-time maximum wave height estimates over the Mediterranean Sea
Authors: Oikonomou Charikleia L.G. , Korres Gerasimos
Published: March 2024

The Med-WAV system of the Mediterranean component (MED MFC) of the Copernicus Marine Environment Service has consistently been providing high-resolution wave product analyses, forecasts, and reanalyses. Accurately predicting wave parameters, particularly during storms, is crucial for ensuring maritime safety, the resilience of offshore structures, and managing coastal hazards. Consequently, since November 2023, the Mediterranean Sea Waves Analysis and Forecast product (MEDSEA_ANALYSISFORECAST_WAV_006_017, Korres et al., 2023) has been delivering estimates of the maximum crest-to-trough height, utilising the methodology proposed by Benetazzo et al. (2021). The system's ability to represent short-term maximum wave statistics is assessed through a comprehensive evaluation against buoys positioned in the western part of the basin, accessible via Copernicus Marine in-situ TAC (2023) (product INSITU_GLO_WAV_DISCRETE_MY_013_045). The results confirm that the operational system adeptly estimates maximum wave height over the Mediterranean Sea in accordance with the quality metrics identified in previous literature.ReferencesKorres, G., Oikonomou, C., Denaxa, D., & Sotiropoulou, M. (2023). Mediterranean Sea Waves Analysis and Forecast (Copernicus Marine Service MED-Waves, MEDWAΜ4 system) (Version 1) [Data set]. Copernicus Marine Service (CMS). https://doi.org/10.25423/CMCC/MEDSEA_ANALYSISFORECAST_WAV_006_017_MEDWAM4Benetazzo A., Barbariol F., Pezzutto P., Staneva J., Behrens A., Davison S., Bergamasco F., Sclavo M. and Cavaleri L. (2021). Towards a unified framework for extreme sea waves from spectral models: rationale and applications. Ocean Eng. 219, 108263. https://doi.org/10.1016/j.oceaneng.2020.108263Copernicus Marine in situ TAC (2023). Copernicus Marine In Situ - Global Ocean Wave Observations Reanalysis. SEANOE. https://doi.org/10.17882/70345
Towards developing a streamflow forecasting system for data-poor mountainous watershed: an approach using parameter transfer
Authors: Mammali Kavya , Jha Sanjeev Kumar , Kouwen Nicholas
Published: March 2024

Studying the hydrological responses of the Indian Himalayan Region (IHR) is crucial given the rise in the frequency of floods and other natural disasters. The hydrological processes in this area are more complicated due to the extreme weather pattern and varied topography. Streamflow forecasting is made more difficult by the extremely low number of stream gauge stations and the absence of accurate stream flow data. The problem of lack of observational data in ungauged watersheds can be resolved by transferring model parameters from similar gauged basins (Regionalisation). According to the traditional regionalization procedures using rainfall-runoff models, donor and recipient catchments must be similar in a variety of ways, including slope, size, drainage pattern, area, etc. It is extremely difficult to locate a catchment with all those similarities. In this study, we use a fully distributed hydrological model WATFLOOD for developing a streamflow forecast of the Alakananda River basin where the stream flow observation is very limited for the calibration of the hydrological model. WATFLOOD is working based on Grouped Response Unit (GRU). The requirement that has to be satisfied for regionalization using the WATFLOOD model is that land cover classes of the ungauged watershed should be represented in the gauged watershed irrespective of their spatial distribution. Also, there should be as many as possible gauged sub-watersheds that represent each land cover class. We identified a similar watershed that has similar land cover classes and sufficient stream flow gauges to represent each of the land cover classes. The three-step calibration process of the WATFLOOD model for both river basins is carried out to transfer the parameters. The results of ongoing work will be presented at the conference.
The uplift of East Africa-Arabia swell: the signature of the mantle upwelling and spreading
Authors: Sembroni Andrea , Faccenna Claudio , Becker Thorsten W. , Molin Paola
Published: March 2024

The East Africa - Arabia topographic swell is an anomalously high-elevation region of ~4000 km long (from southern Ethiopia to Jordan) and ~1500 km wide (from Egypt to Saudi Arabia) extent. The swell is dissected by the Main Ethiopian, Red Sea, and Gulf of Aden rifts, and characterized by widespread basaltic volcanic deposits emplaced from the Eocene to the present. Although most agree that mantle plumes play a role in generating the swell, several issues including the number and locations of plumes and the uplift signatures remain debated. We seek to address these questions and provide a general evolutionary model of the region. To this end, we conduct a quantitative analysis of topography to infer isostatic and dynamic contributions. When interpreted jointly with geological data including volcanic deposits, the constraints imply causation by a single process which shaped the past and present topography of the study area: the upwelling of the Afar superplume. Once hot mantle material reached the base of the lithosphere below the Horn of Africa during the Late Eocene, the plume flowed laterally toward the Levant area guided by pre-existing discontinuities in the Early Miocene. Plume material reached the Anatolian Plateau in the Late Miocene after slab break-off and the consequent formation of a slab window. During plume material advance, buoyancy forces led to the formation of the topographic swell and tilting of the Arabia Peninsula. The persistence of mantle support beneath the study area for tens of million years also affected the formation and evolution of the Nile and Euphrates-Tigris fluvial networks. Subsequently, surface processes, tectonics, and volcanism partly modified the initial topography and shaped the present-day landscape.
How did the Permian-Triassic hot house climate shape the vegetation landscape and how did the land plant fight back?
Authors: Xu Zhen , Yu Jianxin , Hilton Jason , Lomax Barry H. , Wignall Paul B. , Mills Benjamin
Published: March 2024

During the Permian-Triassic Mass Extinction (PTME) ~252Ma, diverse lowland forests were replaced by low diversity pioneer herbaceous lycopod communities that proceeded to dominate the Early and Middle Triassic landscape. The flourishing of Early-Middle Triassic herbaceous lycopods was coincident with data that suggests lethally warm surface temperatures (>40ºC) occurred across large regions of the planet. To explore how these plants were able to thrive during this interval of enhanced climatic stress, we collected data from over 400 fossil plant specimens from South China, supplemented by additional data from literature reviews from other regions and geological ages. Our studies on their morphology indicate that among all Phanerozoic lycopods the transitional Permian-Triassic genus Tomiostrobus (=Annalepis) has the closest morphological relationship with the recent lycopod Isoetes.Extant Isoetes are renowned for their flexibility with regard to the photosynthetic pathway they use and their capacity to absorb CO2 through their roots. To evaluate whether this photosynthetic flexibility was linked to their Early-Middle Triassic ecosystem dominance, we undertook carbon isotope and sedimentary facies analysis including plant taphonomy to test for the presence of the Crassulacean Acid Metabolism (CAM) photosynthetic pathway. Plants capable of CAM pathway growing in stressful environment typically have heavier isotopic signatures while show typical C3 plant signatures in hospitable environment. Our carbon isotope data shows that Permian Triassic Transition Tomiostrobus isotopic signature is on average ~2‰ less negative when compared to contemporary non lycophyte vegetation. Furthermore, the carbon isotope of the Middle Triassic lycopods ~1.07‰ heavier than the other plants, while Late Permian Lepidodendron exhibits a similar δ13C value with other contemporary plants. These findings suggest that CAM photosynthesis may have played a role in the dominance of the Triassic herbaceous lycopods. The dominance of CAM plants following the PTME has implications from an Earth Systems standpoint due to their diminished productivity and a lower capacity for biotic weathering, features that likely suppressed negative feedback loops important in driving climate stabilization during the ~5Ma PTME recovery phase.
Greenhouse gas (CO2, CH4, N2O) emissions from soil fauna – what have we learned over the past decade?
Authors: Görres Carolyn-Monika
Published: March 2024

Soils harbor a diverse fauna, ranging in size from
Object-based characterization of continental Shallow Cumulus Cloud properties using high-resolution Sentinel-2 observations
Authors: Ritter Oscar , Deneke Hartwig , Bley Sebastian
Published: March 2024

Shallow convective cumulus clouds (ShCu) play a major role in determining the global radiation balance and the water cycle. However, such clouds are characterized by small-scale spatiotemporal variability that is inadequately represented in observations and climate models, making ShCu a significant contributor to uncertainty in future climate projections. While large observational efforts have been devoted to better understand the mechanisms of marine ShCu in the Tropical trades, continental ShCu has received less attention.Using 7 years of very high-resolution multispectral images with 10x10m2 pixel size acquired by polar-orbiting Copernicus Sentinel-2 satellites we will give the first analysis of these high-resolution observations focused on continental ShCu around the Central Facility of the ARM Southern Great Plains site in the United States. We will show, that the clouds and cloud shadows can be considered as individual objects with associated properties, such as shape and size parameters as well as their geometric relationship, but also as part of an object field. The cloud fraction, cloud-size-distribution and organization index are calculated for various continental ShCu scenes. The influence of large-scale meteorological conditions and surface properties on the cloud fields will be discussed.Furthermore, a technique will be presented for deriving cloud height and cloud thickness from Sentinel-2 observation, which exploits the geometric relationship between cloud objects and their shadows. The satellite-based estimation will be evaluated using ground-based observational data at the ARM Southern Great Plains Facility, such as the Clouds Optically Gridded by Stereo (COGS) 4-D cloud product. We will discuss how cloud height affects the properties of the cloud fields and thus the radiative forcing.
Effects of biogenic emissions on an extreme event of tropospheric ozone pollution over southwestern Europe (Iberian Peninsula)
Authors: Segado Moreno Leandro Cristian , Sánchez-Jiménez Francisco , Raluy-López Eloisa , Montávez Juan Pedro , Jiménez-Guerrero Pedro
Published: March 2024

Biogenic emissions are those emitted by natural sources such as plants, trees and soil. The main biogenic volatile organic compounds (BVOCs) involved in these emissions are isoprene and monoterpenes, which can undergo photochemical reactions in the atmosphere and contribute to the formation of tropospheric ozone. Warmer temperatures and increased solar radiation can intensify emission rates. On the other hand, different BVOCs may respond differently to water stress. For example, isoprene emissions have been observed to decrease under water stress conditions, while emissions of some monoterpenes may increase. Therefore, the study of biogenic emissions is essential for understanding the Earth's atmosphere, especially in the context of climate change and air quality. To understand the interactions between biogenic emissions and near-surface ozone, advanced atmospheric models are required.This study presents a series of meteorology-chemistry online coupled simulations using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) to investigate the sensitivity of surface ozone concentration to changes in biogenic emissions during an extreme ozone concentration event (12-15 July 2022) over the Iberian Peninsula. Biogenic emissions are introduced into WRF-Chem using the Model of Emissions of Gases and Aerosols from Nature (MEGAN) version 2.04. The experiments consist in varying the biogenic emissions by perturbing parameters related to the emission rates and the type and amount of vegetation.Preliminary results show that the inclusion of biogenic emissions can increase the near-surface ozone concentrations by up to 30% in some locations. Although we do not obtain a much better performance of the model in representing the observed ozone series, the observed extreme values can be better explained when biogenic emissions are considered. Therefore, it is fundamental to consider both natural and anthropogenic sources when addressing ozone pollution. Acknowledgements: Project PID2020-115693RB-I00 funded by MCIN/ AEI /10.13039/501100011033
Ice cauldrons and their relationship with volcanic and geothermal activity in ice-covered volcanoes in Iceland
Authors: Gudmundsson Magnus Tumi , Hognadottir Thordis , Reynolds Hannah I. , Magnusson Eyjolfur , Palsson Finnur
Published: March 2024

About 10% of Iceland is covered by glaciers, including three of the four most active central volcanoes, Grímsvötn, Katla and Bárðarbunga, where the ice-filled calderas have glacier thickness of several hundred meters.  Ice cauldrons, defined as circular or elongated depressions in the surface of glaciers which form due to enhanced basal melting, are very common in the ice-covered volcanic areas in Iceland.  Many have concentric crevasses.  Over 100 cauldrons have been identified in the glaciers of Iceland, with over half being located within or adjacent to the calderas of Grímsvötn, Katla and Bárðarbunga.  Ice cauldrons are usually a sign of subglacial geothermal activity, while occasionally cauldrons are formed during subglacial volcanic eruptions.  Some cauldrons are short term features, existing for some years, indicating transient geothermal activity or recent occurrence of a volcanic eruption.  Others are semi-stable features that have existed for several decades, possibly centuries.  Stable cauldrons are always associated with geothermal activity and the same applies to many of the intermittently active ones as well.  Cauldrons formed in volcanic eruptions tend to be deep and with larger depth/width ratios than geothermal cauldrons.  The widest cauldrons observed in Iceland reach 4-5 km in diameter while diameters of 0.5-1.0 km are the most common.   The size and form of geothermal ice cauldrons depends to a considerable degree on the ice thickness.  Where thickness is small (
Advancing understanding on aviation's non-CO2 climate effects through combination of numerical modelling and observations: ACACIA
Authors: Matthes Sigrun , Bellouin Nicolas , Dedoussi Irene , Fuglestvedt Jan , Gierens Klaus , Hauglustaine Didier , Kanji Zamin , Krämer Martina , Lee David , Lohmann Ulrike , Petzold Andreas , Quaas Johannes , Righi Mattia , Weinzierl Bernadett
Published: March 2024

Non-CO2 emissions contribute to climate effects from aviation in the same order of magnitude as carbon dioxide (CO2) emissions. However, the non-CO2 effects, comprising e.g., ozone and methane induced from NOx emissions, together with contrails, or the indirect aerosol effects, are associated with much larger uncertainties. The EU Aeronautics project ACACIA (Advancing the SCience for Aviation and ClimAte) explored the climate impacts of non-CO2 effects which show a strong dependence on atmospheric conditions and synoptic situation. While CO2 and non-CO2 effects in general introduce a warming effect for climate change, some indirect effects might result in a relatively large cooling.ACACIA investigated indirect aerosol effects comprising formation and properties of clouds. Atmospheric conditions for the formation of long-lived contrails have been investigated, with the aim to improve their predictability. Indirect effects of nitrogen oxide emissions on atmospheric ozone and methane have been estimated, using a set of global chemistry-climate models. These different effects have been brought to a common scale by various physical climate metrics. A dedicated study on prevailing uncertainties has been performed, with the goal to provide robust recommendations considering uncertainties of individual estimates. Together with the numerical studies a dedicated analysis of existing measurement data has been completed in order to identify needs and requirements for atmospheric observations.To this end, ACACIA brought together research across scales, from plume to global scale, from laboratory experiments to global models resulting in a series of scientific publications, and it proceeds from fundamental physics and chemistry to the provision of recommendations for policy, regulatory bodies, and other stakeholders in the aviation business. Acknowledgements This project ACACIA (Advancing the scienCe for Aviation and ClImAte) receives funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 875036. High performance supercomputing resources were used from the German DKRZ Deutsches Klimarechenzentrum Hamburg.
Continuous atmospheric CO2 across the Mid Pleistocene Transition from boron isotopes: decoupling of CO2 from insolation and temperature
Authors: Chalk Thomas , Nuber Sophie , Stap Lennert , Scherrenberg Meike , Zhang Xu , Hain Mathis , Brown Rachel , Yu Jimin , Anderson Morten , Barker Stephen , Rae James , Foster Gavin
Published: March 2024

Changes in atmospheric CO2 and global ice volume as a response to changes in insolation are one of the Earth’s most important feedback mechanisms during glacial-interglacial cycles. During the obliquity paced glacial-interglacial cycles of the 41kyr world prior to 1.2 million years ago (Ma), the response between insolation and the CO2-ice volume feedback is relatively linear. However, during the Mid-Pleistocene transition (0.6Ma – 1.2Ma), this linear response breaks down leading to a large increase in ice volume with a relatively modest decrease in CO2 during glacials in late Pleistocene. Here, we present atmospheric CO2 records derived from boron isotopes measured in the planktic foraminifera G. ruber sensu stricto from 3 ocean sediment cores, each well validated against ice records of CO2. We find two notable CO2 features during the MPT, an early de-coupling of CO2 and ice volume from insolation during MIS 36 (~1.05 Ma), where CO2 stays relatively constant despite multiple (but muted) orbital cycles. Secondly, during MIS 22 (0.9Ma), CO2 decreases step-wise, in combination with rising global ice volume, and recovers to “luke-warm style” interglacial levels in the following interglacial MIS 21. The periods of low CO2 and high ice volume occur in line with saltier Atlantic deep waters enriched in δ13C which we interpret as southern origin water masses, and increased ocean carbon storage. We therefore conclude that changes in ocean circulation may have caused an increased uptake of atmospheric carbon during these periods. In contrast, global sea surface temperatures during MIS36 follow insolation and not CO2 suggesting a de-coupling of the CO2/ice volume feedback from insolation and temperature. This may have prepositioned the climate system for the significant CO2 reduction and ice sheet expansion during and after 0.9Ma.
Unprecedented Aquifer Mapping of Arid Region, NW India for Groundwater Sustainability 
Authors: Tiwari Virendra , Chandra Subash , Ambast Sunil , Ngri-cgwb Team
Published: March 2024

The Arid region, NW India spreads over the great Thar deserts, Precambrian of Aravalli’s, recent alluvium, Deccan basalts and so on, and inhabits ~ 80 million people. Freshwater resources in the region are scarce and contaminated at places, which threaten long term availability of water for agriculture, domestic, and environmental needs therefore, requires a good plan for groundwater exploration and the sustainable management of water resources. The subsurface hydrostratigraphy and conceptual models of the aquifer systems are crucial for developing a sustainable groundwater management plan in these challenging environments. Considering, the constraints of accessibility and traditional methods of aquifer mapping, state of art heliborne geophysical methods are utilized which are supplemented by ground TEM, EVRI, ERT, and drilling information to map subsurface hydrostratigraphy of about 100,000 sq. km area in the diverse geological terrains of the region. These extensive studies have provided 3D geophysical model of principal aquifer with delineation of de-saturated and saturated aquifers, and aquifer system with relatively fresh and saline water zones with unprecedented spatial resolution of a few hundred meter along the flight lines spaced at 2-5 kms. On the basis of information’s of geometries and properties of the aquifer systems, places for potential drilling wells and sites for managed aquifer recharge are demarcated which can enable better management plan for groundwater sustainability.+ Team NGRI-CGWB 
2D reactive transport model for assessing the chemical evolution of a low and intermediate-level waste repository in clayrock
Authors: Montoya Vanessa , Garibay-Rodriguez Jaime
Published: March 2024

In this contribution we have developed a reactive transport model to assess the hydro-chemical evolution of a L-ILW disposal cell in indurated clay rocks, involving the interaction of different components/materials and the expected hydraulic and/or chemical gradients over 100 000 years. The L-ILW disposal cell leverages a multi-barrier concept buried between 200 and 800 m below the surface. The multi-barrier system is comprised of the waste matrix (i.e. backfilling the waste drums), the disposal container, the mortar backfill in the emplacement tunnel (where the disposal containers are located) and the clay host rock. The dimensions and design of the emplacement tunnel (e.g. 11 × 13 m) and disposal cells represent and consider some aspects taken into account in the designs of some European countries. In addition, tunnel walls reinforced with a shotcrete liner and the Excavation Damaged Zone is considered in the concept. The model is implemented in OpenGeoSys-6, an open-source version-controlled scientific software based on Finite Element Method which is capable of handling fully coupled hydro-chemical models by coupling OpenGeoSys to iPHREEQC. First calculation results, demonstrate that the most important processes affecting the near-field chemical evolution are i) the degradation of the concrete and cementitious grouts with porewater migrating inwards from the host rock and ii) the significant quantities of reactive and non-reactive gases (i.e. hydrogen, carbon dioxide and methane) that are generated as a result of: i) the anaerobic corrosion of metals present in the waste and containers and ii) the degradation of organic compounds by microbial and chemical processes. Several simulation cases were carried out under different assumptions, specially related to the saturation of the domain, the final goal was to have a 2D model of the system representing a more realistic geometry which will potentially help in design optimization decisions.
Enhancing Sorption and Biodegradation: The Influence of Inoculated Biochar on the Transport of Organophosphorus Pesticides in Sandy Soil
Authors: Kragulj Isakovski Marijana , Jevrosimov Irina , Tamindžija Dragana , Apostolović Tamara , Rončević Srđan , Maletić Snezana
Published: March 2024

This study investigates how soil enriched with carbon-rich materials, such as biochar, influences the sorption and biodegradation capabilities of organophosphorus pesticides (Fenthion, Fenitrothion, Parathion Methyl) under nonequilibrium conditions. Additionally, experiments were conducted to enhance the biodegradation potential of biochar from Miscanthus×giganteus by introducing bacteria capable of degrading organophosphorus pesticides (OPPs).Transport experiments were carried out in stainless-steel columns (4 cm diameter, 20 cm length) filled with soil amended with biochar previously inoculated with a biofilm of vegetative cells from the Bacillus megaterium BD5 strain. To assess the impact of inoculated biochar on pesticide transport, 0.5% of this adsorbent was added to the total soil mass in the column. Thiourea was included as a tracer at a concentration of approximately 4 mg/L. Pesticide solutions were pumped through the column, and eluates from the outlet were collected at various time intervals, and analyzed for pesticide concentrations using GC/MS Agilent 7890 A/5975C.Data analysis involved the use of a mathematical transport model by solving the advection-dispersion equation (ADE), yielding transport parameters (retardation, Rd, and biodegradation, λ) and breakthrough curves. The retardation coefficient for investigated compounds ranged from Rd=40-100, with increasing order of Parathion-methyl < Fenthion < Fenitrothion. Biodegradation (λ) of the compounds ranged from λ=0.2-3.3, increasing in the same order. No clear correlation was observed between the octanol-water partition coefficient (Kow), retardation, and biodegradation, indicating that hydrophobicity alone did not solely determine sorption and transport characteristics under specific experimental conditions.In summary, introducing inoculated biochar likely contributes to the simultaneous adsorption of organic compounds onto the added adsorbents within the porous material and biosorption onto the inoculated biochar. Generally, adding inoculated carbon-based materials to contaminated sediments shows potential as a remediation technique, inhibiting pollutant leaching to groundwater and facilitating immobilization. Keywords: transport, biochar, organophosphorus pesticides, biodegradationAcknowledgment 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 the European Research Executive Agency (REA). Neither the European Union nor the granting authority can be held responsible for them. Grant agreement No. 10105954
A two-phase Neural Model for CMIP6 bias correction
Authors: Pasula Abhishek , Subramani Deepak
Published: March 2024

The Coupled Model Intercomparison Project, now in its sixth phase (CMIP6), is a global effort to project future climate scenarios on following certain shared socioeconomic pathways (SSP). For the period 1950-2014, CMIP6 provides a historical model output. From 2015 future projections with four different SSP scenarios, viz. SSP126, 245, 370 and 585 are available. From 2015-2023, we also have reanalysis of the actual ocean and atmosphere variables in these years. From this data, it is observed that CMIP6 future projections of ocean variables have a root mean square error (RMSE) of 1.22 psu in sea surface salinity, 1.24 °C in sea surface temperature, 2.23 m/s in the zonal ocean velocity component, 1.34 m/s in the meridional ocean velocity component. Similarly, the atmospheric variables have a RMSE of 1.34 °C in temperature at 2-meter height, 2.12 m/s in the zonal, and 1.321 m/s meridional wind component. Our goal is to develop an accurate method to correct this bias and provide updated future projections for scientific analysis. To this end, we developed a two phase deep neural network model that accepts monthly fields from the CMIP6 projections (all four SSP scenarios), and outputs a bias corrected field. In the first phase, a deep neural model, which we call as Atmospheric-Ocean Network 1 (AONet1) is used to obtain bias corrected fields for each of the four SSP separately. The AONet1 is trained and validated using the historical CMIP6 data (1950-2014) as input and ORAS5 and ERA5 data as the output (the bias corrected field). In the second phase, the four bias-corrected SSP fields are fed to AONet2 and the final bias corrected single field is produced. The AONet2 is trained and validated using future projection data from 2015-2021 as input and ORAS5 and ERA5 from the same period as output. The testing of the two phase model is performed for years 2022 and 2023, before bias corrected future fields are produced. Results are compared to the statistical EDCDF method using different Image Quality Assessment metrics such as Data structural similarity index measure (DSSIM), Multi-Scale SSIM, and Visual information fidelity. On test data, the RMSE after bias reduction using the two phase AONet model is 40% lower. Image assessment metric values surpassed the EDCDF approach as well.
Integrated model-measurement approaches to chamber SOA studies
Authors: Kenagy Hannah , Heald Colette , Tahsini Nadia , Goss Matthew , Kroll Jesse
Published: March 2024

Many of the quantitative descriptions of secondary organic aerosol (SOA) formation in regional and global models are derived from environmental chamber experiments, an experimental approach commonly used to assess multi-phase product distributions from atmospheric oxidation pathways.  As such, model accuracy for predicting aerosol abundance hinges on our ability to represent atmospheric conditions in chambers.  Here, we develop a new experimental approach that leverages both global modeling and detailed mechanisms to design chamber SOA experiments that capture atmospheric chemical environments for two key branching points in VOC oxidation: atmospheric oxidant balances and atmospheric RO2 chemistry. Using isoprene as a model system for multi-generation SOA production, we focus first on competition between oxidation by OH and Cl.  Global modeling indicates that multi-oxidant, multi-generation oxidation outcompetes single-oxidant, multi-generation oxidation in this system; we design and perform a series of chamber experiments to measure multi-phase product distributions from multi-oxidant, multi-generation isoprene oxidation.  Second, we develop a framework for quantitatively describing atmospheric RO2 chemistry and show that no previous experimental approaches to studying SOA formation have accessed the relevant atmospheric RO2 chemistry.  Leveraging multi-scale modeling, we design and perform a series of chamber experiments to measure isoprene SOA production under a range of atmospheric RO2 fate distributions.
Mitigating Carbon Loss Risks through Natural Climate Solutions Portfolios
Authors: Cerasoli Sara , Porporato Amilcare
Published: March 2024

Natural climate solutions (NCS) hold the potential to realize a significant portion of emission reductions. However, uncertainties surrounding their efficacy impede their full utilization. In this study, we leverage Modern Portfolio Theory to construct NCS portfolios (NCSPs) that encompass diverse pathways outlined in Griscom et al. Within a 'carbon mitigation market,' these pathways are regarded as risky assets, with their returns and risks determined by global estimates of mitigation potential.Our objective is to optimize carbon sequestration while minimizing the risk of carbon loss, effectively navigating the 'efficient frontier' where the optimal trade-off between maximum carbon sequestration and risk is achieved. Diversification of pathways results in reduced risk and increased resilience, especially when the risks of carbon loss from environmental stressors are spatially or temporally uncorrelated.The optimal NCSPs offer valuable insights into allocating investments and land across pathway categories (forests, agriculture, and wetlands), intervention types (e.g., manage, protect, restore), cost-effectiveness, and geographical contexts. We trust that these findings will assist policymakers in mitigating risk while pursuing ambitious carbon mitigation targets.
Tracking biogeochemical processes in a Subterranean Estuary (STE): Application of a multidisciplinary approach integrating isotopes, hydrogeochemistry, and dissolved organic matter (DOM) 
Authors: Almillategui Bella , Rodellas Vila Valenti , Saaltink Maarten W. , Carrera Jesus , Folch Albert
Published: March 2024

Subterranean Estuaries (STEs) have been recognized for their role in the transport and fate of chemical compounds that discharge to the coastal ocean. The enrichment of coastal groundwater with nutrients is affected by different sources and mechanisms. Moreover, the distribution of these substances discharging to the sea is highly affected by the reactions produced at the mixing zone between the fresh and saline groundwater. In this research, we aim to identify the nutrient sources and biogeochemical processes that are actively playing a role in the subterranean estuary located in the alluvial aquifer of Argentona, in the northeast of Barcelona, Catalonia (Spain).Coastal groundwater in the area has been continuously explored since 2014 with the development of a unique experimental site. The site is 100m long inland from the coastline and 30m wide. It is being monitored with 25 piezometers consisting of 5 nests with 4 piezometers each (with intervals at 10m, 20m, 15m, and 25m) and 4 individual piezometers, equipped with different sensors that collect data every 15 minutes.This study integrates various approaches such as the N-isotopes (δ15N-NO3-, δ18O-NO3-, δ15N-NH4+), hydrogeochemistry, dissolved organic matter (DOM), and bacteria concentration that has been measured in all piezometers during two sampling campaigns (winter and summer). The results show potential sources of ammonium and nitrate and the biogeochemical transformations that have a main role in the subterranean estuary dynamic.AcknowledgmentsThis work was funded by the Spanish Government under the project MUCHOGUSTO (grant no. PID2022-140862OB-C21/C22) and the SENACYT – BID Scholarship by the Panamanian Government.
Discussing modifications to Station XML format to accommodate the needs of mobile stations associated with current EarthsScope-Oceans Initiatives
Authors: Bianchi Marcelo , Coelho Diogo L.O. , Maurício Ítalo C.B.S. , Chaves Carlos A. M. , Fontes Sergio L. , Borges Ricardo G. , Simon Joel D. , Ahern Timothy K.
Published: March 2024

Over the last 5 years, Petrobras has been running the PMBAS-BS project collecting hydroacoustic data allowing them to monitor the sea life near the platform, co-existing with its Exploration and Production operation. PMBAS-BS has so far accumulated a dataset of Sea Glider campaigns and a series of mooring lines with acoustic sensors. This work focused on integrating this dataset into a SeisComp system that allowed the processing of PMBAS-BS data together with data from the Brazilian Seismographic Network (RSBR). The major issue faced by the team is the handling of the metadata. A concept that is widely agreed upon is that seismographic instrumentation operates in Epochs during which some instrumentation parameters are immutable. A different approach is faced inside EarthScope-Oceans initiatives where the acoustic sensors monitoring the oceans associated with the MERMAID platform are moving instrumentation. Such a paradigm is also applicable to ARGO platforms, Sea Gliders, and other ocean monitoring instruments, i.e. they are launched at a certain point over the Earth and constantly change their position with time that has a direct impact since the coordinates of the metadata Station (MERMAID) is rapidly changing with time. When they surface, they collect a new coordinate that is true only for the instant. Supporting this kind of metadata involves understanding the coordinates as sampled data and not epochs, as adopted on land instrumentation. The normal sampling rate of coordinates ranges from a sample per week to a sample per month. Recently the International Federation of Digital Seismograph Networks (FDSN) working group V approved the GeoCSV proposal, as an approach to handle Rapidly Changing Metadata (RCM) in the EarthScope-Oceans environment. While GeoCSV was a simple solution to allow the initial data to be shared inside the FDSN framework, it is viewed as an intermediate step focussed on Metadata capture.  GeoCSV with the RCM will be merged within the current Station XML structure and thereby the RCM will become a subelement of current StationXML and not stored in a separate GeoCSV file. The process of developing this next version of StationXML that incorporates RCM will be closely coordinated with FDSN Working Group II that oversees the SEED format along with Station XML. In this work we intend to present at least one manner that the EarthScope-Oceans consortium believes that the GeoCSV information could be rendered inside the Station XML.
Towards monitoring subsurface marine heatwaves based on sea surface properties in the Eastern Pacific
Authors: Köhn Eike E. , Münnich Matthias , Vogt Meike , Gruber Nicolas
Published: March 2024

As marine heatwaves (MHWs) become a growing concern for marine ecosystems, an effective ecosystem management necessitates precise monitoring of such periods with exceptionally high water temperatures. As satellite-based temperature measurements do not reach beyond the sea surface, identifying subsurface MHWs has so far relied on lower-resolution data obtained from (autonomous) in-situ measurements. In this study, we assess to which extent subsurface MHWs, defined statically by a seasonally varying 90th percentile, can be deduced from surface properties that can be remotely-sensed at a high spatio-temporal resolution. To this end, we build a Random Forest (RF) classification model with daily data from a high-resolution numerical hindcast simulation focused on the Eastern Pacific (1979-2019). The RF is trained to distinguish between extreme and non-extreme temperatures at the depth of the climatologically maximum mixed layer depth (MLD), i.e. a depth that is decoupled from the sea surface throughout most parts of the year. We train the RF on the first 80% of the hindcast simulation data (i.e., 1979-2011) and use a range of predictor variables, such as anomalies of sea surface temperature (SST), height (SSH) and salinity (SSS) as well as derivatives of these physical variables. Testing the model on the last 20% of the hindcast simulation (2012-2019), the RF correctly identifies more than two thirds of all subsurface extreme states, leaving only about 30% of subsurface extremes unidentified. Yet, of all RF-based subsurface extreme classifications, about 40% of subsurface temperatures are false positives. Nevertheless, the RF model outperforms a simple SST based extrapolation of extreme states into the ocean interior. The RF-based classification is mostly guided by SSH and SST anomalies (together reduce impurity by about 50%), followed by climate indices like the Oceanic Niño Index (ONI) and the Pacific Decadal Oscillation (combined impurity reduction by 20%). This simulation-based study emphasizes the potential of exploring remote sensing data, particularly SST and SSH, to extend the monitoring of MHWs beneath the sea surface. Integrating this high-resolution statistical estimate with lower-resolution in-situ hydrographic information has the potential to make subsurface MHW monitoring a feasible and valuable tool for marine ecosystem management.
On the reversibility of Arctic sea ice loss
Authors: Rynders Stefanie , Aksenov Yevgeny , Schwinger Jörg , Bourgeois Timothée , Jones Chris
Published: March 2024

It is now expected carbon emissions will follow an overshoot trajectory. A realistic emission-driven overshoot scenario esm-SSP534-over is available from the CMIP6 archive. We analysed the simulations to examine reversibility of the Arctic sea ice cover. Reversibility here means that at the end of the 21st century the sea ice extent is the same as that at the earlier point in the century with the same atmospheric CO2 concentration. Firstly, in an emission driven simulation the system behaves differently on the upward and downward branches of CO2 concentration. We show it is better to use atmospheric CO2 concentration rather than Arctic surface air temperature, as the relation between the two is not linear. Total Arctic sea ice extent shows consistent behaviour in 3 out of 4 models (CNRM-ESM2, MIROC, UKESM1) with a CO2 concentration threshold above which sea ice becomes irreversible. This can be explained by the continued ocean heat transport into the Arctic even though the Atlantic Meridional Overturing Circulation (AMOC) declines. The NorESM model has very different behaviour, sea ice extent is reversible and even overshoots beyond the present-day extent. We suggest this is caused by the known strong AMOC decline in this model. The analysis indicates Arctic air temperature is a result of the changes in sea ice extent rather than the driving factor, as is often assumed, both ultimately controlled by ocean heat transport. From the available simulations we conclude there is large uncertainty in the future Arctic climate state. This uncertainty extends to the future global air temperatures as different models show different inertia on CO2 concentrations, which only materialises in the downward emission branch. This affects many other climate variables with their own time lag. Climate inertia and time delays in the earth system should be investigated further to improve fidelity of future projection. This necessitates the use of emission-driven scenarios instead of concentration-driven ones which do not allow for the full inclusion of internal earth system feedbacks. We acknowledge funding from the projects COMFORT (grant agreement no. 820989) and OceanNETs (grant agreement no. 869357) under the European Union’s Horizon 2020 research and innovation programme, and from the EC Horizon Europe project OptimESM “Optimal High Resolution Earth System Models for Exploring Future Climate Changes”, grant 101081193 and UKRI grant 10039429, from the project EPOC, EU grant 101059547 and UKRI grant 10038003. For the EU projects the work reflects only the authors’ view; the European Commission and their executive agency are not responsible for any use that may be made of the information the work contains.
Microbial phosphorus limitiation with soil age along a chronosequence on the Galapagos Islands
Authors: Keiblinger Katharina Maria , Socianu Sebastian , Rechberger Maria , Gerzabek Martin , Zehetner Franz
Published: March 2024

The Galápagos archipelago, a volcanic island chain, is comprised of a series of progressively older islands with increasingly weathered soils away from the volcanic hotspot. Volcanic soils are known for their high phosphate sorption capacity. In this study, we explore differences in soil microbial abundance and activity across a soil age gradient (1.5 to 1070 ka) to understand how soil microorganisms are affected by soil development, shifting soil characteristics and P sorption over extensive periods.Basal respiration, substrate-induced respiration and microbial biomass P decreased with soil development, suggesting increasing nutrient limitation for soil microbes. Also, soil enzymatic stoichiometry revealed a limitation driven mainly by P and not by N or C. C- and N-acquiring exoenzyme activities peaked at 26 ka with lower activities in younger and older soils. Phosphatase activity increased with soil age, indicating microbial P limitation in the older soils. This is only partly in line with  P sorption-desorption characteristics along the studied weathering sequence. Phosphate sorption capacity was high in the 4.3 ka soils likely due to amorphous soil constituents. A change towards 2:1-type crystalline clays after 26 ka of soil weathering led to weaker P sorption and stronger desorption, and acidification and increased P occlusion in Al and Fe (hydr)oxides became an important factor for microbial P limitation in the older soils.Our results reveal striking differences in soil properties on the Galápagos Islands, suggesting relatively little nutrient constraints for soil microbes, despite strong P sorption, in the younger volcanic soils but growing P limitation in the older, highly weathered soils. These observations have important bearings on nutrient cycling and may therefore also affect the evolution of plant and animal species on this unique archipelago.
Role of extracellular polymeric substances (EPS) in mineral precipitation in the ocean water column
Authors: Martinez-Ruiz Francisca , Paytan Adina , Vasconcelos Crisogono , Jroundi Fadwa , Abad Maria del Mar , Villasante Victor , Gonzalez-Muñoz Maria Teresa
Published: March 2024

The investigation of mechanisms involved in barite formation in the mesopelagic zone has served to demonstrate the importance of extracellular polymeric substances (EPS) in promoting microenvironments in which Ba can precipitate. Barite formation in the ocean was not fully understood until experimental work and observations from microenvironments of intense organic matter mineralization in the ocean water column demonstrated the role of bacteria and EPS in concentrating Ba. The organomineralization processes leading to barite formation are expected to be similar to those involved in the formation of other biominerals in which bacterial cells and EPS provide charged surfaces that bind metals inducing mineralization. Thus, EPS production plays a major role in promoting locally high concentrations of Ba leading to barite precipitation. Regarding the crystallization pathway, scanning and high-resolution transmission electron microscopy analyses have shown the occurrence of P-rich amorphous precursor phases, which supports that phosphate groups in EPS and bacterial cells are the main sites for binding Ba. These P-rich amorphous particles evolve into poorly crystallized barite and eventually into micrometer-sized barite crystals. The ubiquitous presence of bacteria and EPS in aquatic systems, and in the mesopelagic zone at depths of intense organic matter mineralization, and their inherent ability to biomineralize, make them extremely important agents in driving the Ba biogeochemical cycle. Thus, further investigating microbial processes in the open ocean is essential to better understand metal cycling. The strong link between organo-mineralization and microbial processes further supports the microbial role in biogeochemical cycles. Other than Ba, EPS may also play an important role in concentrating other metals in seawater, which still needs further investigation.