bluuebunny/crossref_metadata_2025 huggingface dataset:
Fluid Mud Occurrence in the Hyper-Turbid Ems Estuary: Insights into Tidal Cycle Influence
Authors: Slabon Aron , Holthusen Dörthe , Rovelli Lorenzo , Fiskal Annika , Schöl Andreas , Rössler Ole , Hoffmann Thomas , Borgsmüller Christine
Published: March 2024

The Ems estuary (NW Germany) is characterized by a hyper-turbid state with sediment concentrations ranging from < 1 g/L up to several hundred grams per liter. In summer, when upstream discharge decreases and biomass production increases, substantial fluid mud layers (sediment concentration > 10 g/L) accumulate, particularly during low tides. The thickness of the fluid mud layer reaches a significant fraction of the water column (up to 60%), thus affecting cross-sectional hydrodynamics as well as navigability. Extensive monitoring with high temporal and vertical resolution is required to understand the processes controlling the formation and compaction of the fluid mud layers, given their high temporal and spatial variability.Between August 2019 and September 2019, two vertical probe arrays were installed in the Lower Ems estuary (km 11.775) equipped with multi-parameter probes (pressure, salinity, oxygen, and current velocity), optical backscatter turbidity sensors, and additional oxygen loggers. The probes/loggers are deployed at three different depths (approx. 1.15m above bed, 1.95m above bed, and attached to a buoy at the surface) measuring continuously every 5 min. Thus, a high-resolution time series with decent vertical resolution over a period of six weeks has been recorded.Six weeks of monitoring revealed two superimposed cycles of fluid mud occurrence. On a shorter timescale, fluid mud occurrence is separated by distinct stages of formation, entrainment, and stratification throughout a tidal cycle. However, on a longer timescale, fluid mud occurrence is affected by the neap-spring tide. Here, we identify four main stages: buildup, stationary state, breakup, and no presence of fluid mud, each stretching over multiple tidal cycles. Each stage is characterized by distinct differences in, e.g., turbidity, salinity, and oxygen gradients/dynamics. Our approach successfully enables monitoring of fluid mud in the hyper-turbid Ems estuary for a better understanding of the processes of fluid mud formation and breakup. Future research aims to develop predictive models for the occurrence of hyper-turbid conditions and different fluid mud stages in the Ems estuary.
Soil Texture Controls the Relative Importance of Vapor Pressure Deficit and Soil Moisture for Ecosystem Water Limitation Globally
Authors: Wankmüller Fabian J. P. , Delval Louis , Lehmann Peter , Baur Martin J. , Wolf Sebastian , Or Dani , Javaux Mathieu , Carminati Andrea
Published: March 2024

Terrestrial vegetation plays a crucial role for water-energy-carbon interactions between the land and the atmosphere but is experiencing above-average temperature increases due to climate change. This contributes to widespread increases in vapor pressure deficit (VPD). High VPD and low soil moisture are considered the two main drivers of plant water stress, triggering the downregulation of vegetation-atmosphere fluxes, such as transpiration and photosynthesis. While ecosystems are initially driven by energy availability, soil drying below a critical soil moisture threshold (θcrit) shifts them to a water-limited regime. However, the relative importance of VPD versus soil moisture limitation and the relative role of soil versus plant hydraulic conductance are highly debated. Understanding the key mechanisms controlling these relative roles is therefore crucial to predict vegetation-atmosphere exchanges under changing environmental conditions. Here, by analysing global observations of θcrit, we demonstrate the central role of soil texture in shaping the importance of VPD versus soil moisture limitation by mediating the magnitude of soil hydraulic conductance relative to that of the plant. On average, we find that loss in soil rather than plant hydraulic conductance determines the onset of water limitation across climates and biomes globally. This implies that ecosystems in fine textured soils are more sensitive to VPD than ecosystems in coarse textured soils, while ecosystems in coarse soils are more sensitive to soil drying than in fine soils. This is a consequence of the steeper decline in soil hydraulic conductivity in coarse soils, resulting in the dominant control of soil hydraulics in these soils. Our analysis explains the emergent control of soil texture on ecosystem water limitation and unifies long-standing controversies about the relative importance of VPD versus soil moisture and soil versus plant hydraulic limitation. We demonstrate the global relevance of soil texture for land-atmosphere exchanges and open new paths to understanding the impacts of climate change on terrestrial ecosystems.
How high are Jupiter’s clouds? From high-resolution JunoCam images to a multi-wavelength analysis
Authors: Guillot Tristan , Biagiotti Francesco , Davide Grassi , Mike Wong , Leigh Fletcher , Glenn Orton , Eichstaedt Gerald , Rosenqvist Marylyn , Brueshaber Shawn , Hansen Candy , Keaveney Caleb , Kelly Kevin , Momary Tom , Lunine Jonathan , Bolton Scott
Published: March 2024

Last year, we showed that JunoCam images, acquired in the visible, have the resolution necessary to measure the height of clouds from their projected shadows. We focused our analysis on the “Nautilus”, a 3000-km cyclonic vortex seen during Juno’s 14th periojove. That structure consists mainly of a spiraling counter clockwise white cloud that casts a shadow onto a reddish cloud deck∼20 to 30 km below. Small individual clouds also pop out of the white cloud deck, towering about ~10 to 20 km above it. An analysis of near-simultaneous HST images of the Nautilus confirms that the white region is higher than its surrounding darker, reddish cloud deck. These respective elevations are consistent with the white clouds being made of fresh ammonia ice while most of the reddish clouds underneath are made of ammonium hydrosulfide NH4SH, as predicted by equilibrium cloud models.An analysis by F. Biagiotti of a similar region observed by JIRAM during Juno’s 1st perijove identifies the presence of elusive ammonia ice crystals, either pure or mixed with a nitrogen-bearing species similar to Titan’s tholins. In addition, these clouds have altitudes that are consistent with the above interpretation. However, the surrounding material is not much deeper and incompatible with NH4SH. We discuss a possible solution to the corundum: At least in the gas, the atmosphere's optical thickness is much larger at the wavelengths used for the JIRAM study (2 to 3.2 micron)  than in the visible. The effect of scattering by cloud particles is to be evaluated, but it appears likely that altogether, infrared observations at these wavelengths cannot penetrate as deep as visible ones.An interpretation of these observations, consistent with spectroscopic observations in the visible, is therefore that, at least in this region close to ~40°N, most of Jupiter's visible cloud deck is made of NH4SH, that updrafts can locally deliver fresh ammonia ice but that these ammonia ice crystals remain only for a short time either because of downwelling and evaporation or because of coating.
Detection and occurrence rate of ion-scale reconnecting current sheets using Solar Orbiter high cadence data. 
Authors: F. Albert Inmaculada , Toledo-Redondo Sergio , Montagud-Camps Víctor , Castilla Aida , Lavraud Benoît , Fargette Naïs , Louarn Philippe , Owen Christopher , Zouganelis Yannis
Published: March 2024

Magnetic reconnection is process in which magnetic energy dissipates, turning into kinetic and thermal energy, through the reconfiguration of the magnetic field topology. It has been observed in the solar wind at multiple spatial scales and Sun distances.
The study of magnetic reconnection in large- and medium-scale structures has received closer attention than ion-scale magnetic reconnection, due to the instrumental limitations. Thanks to the Solar Orbiter data, and in particular that from the Proton- Alpha Sensor (PAS) from the Solar Wind Analyser (SWA) instrument, we can now resolve ion velocity distribution functions inside current sheets of thicknesses in the range of a few proton gyroradii. Thus, we are granted the possibility of searching for reconnection signatures at scales near the ion spectral break of the turbulent cascade, and we can investigate its prevalence and its impact in heating and accelerating the solar wind.
In this presentation introduce an algorithm we are developing to automatically identify reconnecting current sheets near the ion spectral break in the solar wind. We find that the uncertainty associated with ion bulk velocity measurements constrains the Alfvén velocities that can be resolved with the available data, resulting in a lower threshold for the detectable reconnecting component of the magnetic field.
We present preliminary results, consisting of a catalog of small-scale current sheets in the solar wind and an assessment of reconnection frequency and prevalence. We show the relative occurrence of reconnecting versus Alfvénic current sheets near ion-scales and discuss the relevance of small-scale magnetic reconnection for energy dissipation in solar wind turbulence.
SLAINTE: A sub-daily (In)SAR mission idea to study vegetation water, health and carbon
Authors: Steele-Dunne Susan , Bastos Ana , Dorigo Wouter , Massari Christian , Milodowski David , Miralles Diego , Ciabatta Luca , de Santis Domenico , Tronquo Emma , Zappa Luca , Rodriguez Cassola Marc , Lhermitte Stef , Matar Jalal , Monteith Albert , Taylor Christopher , Tebaldini Stefano , Ulander Lars , de Zan Francesco
Published: March 2024

Changes in sub-daily vegetation water content capture the pulse of the Earth's ecosystems. They reflect the interplay between plant function, evaporation, and soil moisture, and underpin land-atmosphere exchange of water and carbon from leaf to global scales. Current and planned microwave missions provide a snapshot every few days. These are adequate to observe inter- and intra-annual variations of above ground biomass (AGB), the slow response in water status over weeks and months, and to map (a-posteriori) biomass loss due to deforestation or mortality. However, they are not sufficient to capture the sub-daily, or even daily, dynamics needed to study ecosystem health.The SLAINTE (Irish for health) mission aims to fill this critical observation gap at sub-daily scales enabling us to “zoom in” on the fast dynamics associated with water status. Sub-daily observations of VWC are needed to study the vegetation response to the daily cycle in vapour pressure deficit (VPD), the impact of stomatal regulation, and the rate at which vegetation is able to recharge VWC lost during the day. They reveal how ecosystems respond to biotic and abiotic stress (e.g. changing temperature and vapour pressure deficit, soil moisture, insects, disease) and disturbances (e.g. drought, fire). Observing these processes is critical to understand the resilience of terrestrial ecosystems and their water resources in the face of increasing climate variability and extremes, and pressures from human land and water use. The availability of sub-daily SAR data would also fill a critical gap in Earth system knowledge where observations of rapid changes in SSM are essential. For example, they would allow us to observe short-lived wetting/drydown events associated with irrigation, triggering and evolution of flash floods and shallow landslides and the development of hazardous storms.SLAINTE comprises a small constellation of monostatic L-band Synthetic Aperture Radars (SAR) that will provide sub-daily, ≤1 km scale observations related to ecosystem water status. It has been developed as one of ESA’s New Earth Observation Mission Ideas and was recently submitted in response to ESA’s call for the 12th Earth Explorer. Here, we will provide an overview of the SLAINTE mission idea, our ambitions, and an overview of preliminary science studies. We hope to stimulate discussion with the wider EGU community on how the provision of routine, sub-daily (In)SAR observations could be exploited to address the scientific challenges across the geosciences.
Developing an Impulse-Based Intermittent Particle Entrainment Mechanism in Turbulent Flows Using a Multivariate Random Process
Authors: Chang Cheng-Ho , Tsai Christina
Published: March 2024

The Shields parameter, dimensionless time-averaged bed shear stress, has been widely used to predict the onset of bed load particle motion and the magnitude of time-averaged bed load sediment flux in open channel flows. Nevertheless, the limitation of a time-averaged approach becomes evident when addressing near-threshold transport problems, potentially leading to the neglect of critical factors. Studies reported that the impulse criterion (force times its duration) is more effective than the Shields criterion under low-shear conditions.This study focuses on developing an impulse-based entrainment mechanism, incorporating turbulent fluctuation, bed load transport intermittency, and force duration from an instantaneous viewpoint. We characterized the random impulse events time series, covering random intensity, random event duration, and random arrival time, as the energy imparted to particles by turbulent flow. The joint probability density function (PDF) models the event intensity and duration, while the Poisson process governs the random arrivals of impulse events. The essential parameters are extracted from a Direct Numerical Simulation (DNS) data set. A work-based criterion is applied to determine whether a particle will be entrained by the energy it receives. The time-averaged bed load sediment flux is obtained through an existing linkage between impulse events and the sediment flux. The model will be validated using the stress transport relation, where the time-averaged sediment flux is expected to be proportional to the 16th power of time-averaged shear stress at low shear conditions and the 1.5th power of time-averaged shear stress at high shear conditions.This study offers valuable insights into near-threshold transport problems from various perspectives in a stochastic manner. For instance, statistical properties of impulse event duration, intensity, and mean arrival rate that transit from high to low shear conditions are investigated. Furthermore, from a macroscopic and time-averaged view, the stress-transport relation with the uncertainty of time-averaged sediment flux is obtained, showing an increased variability when near the critical threshold. Moreover, from a microscopic and instantaneous view, this study developed a physical-based approach to address particle resting time from a Lagrangian viewpoint. The impulse event random process can be applied as the entrainment mechanism to a Lagrangian stochastic bed load particle tracking model (PTM) to predict the local inception of particles at any instant. The statistical properties of near-bed particle dynamics, such as the particle hopping distance, resting time, and anomalous advection and diffusion, can be comprehensively investigated once a bed load PTM is equipped with the proposed model that considers a physical-based intermittent entrainment random process.
­­­­­ESR-thermochronometry in the western European Alps (Switzerland) 
Authors: Wen Xiaoxia , Bartz Melanie , Schmidt Christoph , King Georgina
Published: March 2024

The western European Alps are characterised by deeply incised valleys, however the timing of their formation and the impact of Quaternary glaciation on rates of erosion remains disputed. This is mainly due to a lack of geochronological methods that cover the timespan of 103-106 years. Electron spin resonance (ESR) thermochronometry has a high potential to fill this temporal gap because of its low closure temperature (
Early Warning of Crossing the 1.5°C Global Temperature Change Threshold
Authors: Rosen Debbie , Jackson Lawrence , Forster Piers , Schleussner Carl-Friedrich
Published: March 2024

With the human induced increase in global temperatures continuing, the question if and how we might exceed the 1.5°C warming level enshrined in the long-term temperature goal of the Paris Agreement has received increased public and scientific interest. Identifying the level of human induced warming at any given year is subject to a range of uncertainty including from short-term natural variability. A single year, or even several consecutive years, above 1.5°C thus does not imply that the human induced warming level is reached but does provide an early warning of the risk of crossing that threshold.Here we find that under an emission pathway following current policies, a single year above 1.5°C might imply that a crossing of the global warming threshold could materialise within 11 years thereafter (66% or likely range). For a three (5) year consecutive average, this time window decreases to 5 (2) years. If 1.5°C is reached in 2024, according to our analysis it would mark an unusual event (about 1-in-25 years) under a current policy scenario that reaches 1.5°C around 2040 (central estimate). We find that stringent emission reductions in the near-term can increase the chances of never crossing 1.5°C. Under a scenario of stringent emission decline, an exceedance of 1.5°C in one or several years may be observed without the long-term warming level ever being breached.The occurrence of a single year at or above 1.5°C should therefore be taken as a final warning for the need for very stringent near term emission reductions to keep the Paris Agreement long-term limit within reach.
PARIS, AVENGERS, EYE-CLIMA - Verification and reconciliation of estimates of climate forcers
Authors: Walter Sylvia , Ganesan Anita , Scholze Marko , Thompson Rona , Röckmann Thomas
Published: March 2024

PARIS, AVENGERS, and EYE-CLIMA represent initiatives funded under the EU Horizon call focused on "Verification and reconciliation of estimates of climate forcers." Drawing expertise from diverse fields such as atmospheric science, ecology, computer science, systems analysis, climate, and emissions reporting, these projects collaborate with the shared objective of refining estimates of greenhouse gas (GHG) emissions through observation-based methodologies. This collaborative effort not only aims to enhance the precision of GHG emission estimates but also facilitates meaningful exchanges with stakeholders involved in policymaking, national greenhouse gas inventories (NGHGIs), government bodies, and non-governmental organizations.Utilizing atmospheric inversion models, the projects establish connections between surface-atmosphere GHG exchanges and atmospheric concentrations. The emissions estimates derived through this method directly correlate with atmospheric observations, remaining independent of activity data and emission factors. Consequently, this approach supports the independent verification of NGHGIs. In essence, PARIS, AVENGERS, and EYE-CLIMA strive to reconcile emissions information to contribute to the effective implementation of the Paris Agreement. Beyond atmospheric inversion methods, the projects incorporate land-surface models, which simulate the processes governing GHG exchanges between the land surface and atmosphere, along with data-driven models. This presentation will provide a comprehensive overview of the three projects, delving into their individual objectives and highlighting the overarching efforts aimed at verifying and reconciling estimates of climate forcers.
Critical thresholds of the Greenland Ice Sheet from the LGM to the future
Authors: Gutiérrez-González Lucía , Alvarez-Solas Jorge , Montoya Marisa , Tabone Ilaria , Robinson Alexander
Published: March 2024

In recent decades the Greenland Ice Sheet (GrIS) has undergone accelerating ice-mass loss. The GrIS is thought to be a tipping element of the Earth system due to the existence of positive feedbacks with the climate. Previous work has shown threshold behavior in the system, and its stability has been studied in a range of temperatures of the present to a global warming of +4K. However, there is still no consensus on the values of its critical thresholds for the future. Furthermore,  its stability at  lower temperatures hasn’t been studied yet. Here we use the ice-sheet model Yelmo coupled with the regional climate model REMBO and a parametrization of the ice-ocean interactions to obtain the bifurcation diagram of the GrIS from temperatures representative of the LGM (-12K) to a warmer scenario (+4K). The preindustrial simulated equilibrium volume is larger than the observations, a feature common to many other ice-sheet models. This could indicate model biases, but also that the GrIS could currently not be fully in equilibrium with the preindustrial forcing, with implications for future projections. To investigate this issue, we simulated the transient evolution of the GrIS since the LGM to the present day in the context of the bifurcation diagram, with equilibrium states acting as attractors. 
The Tipping Point Modelling Intercomparison Project (TIPMIP)
Authors: Winkelmann Ricarda , Dennis Donovan , Donges Jonathan , Loriani Sina , Sakschewski Boris , Rockström Johan
Published: March 2024

While tipping points in the Earth system are recognized in the public and policy debate as one of the major risks of anthropogenic climate change, our current knowledge of their dynamics involves a broad range of uncertainties, and so far there is no systematic risk assessment quantifying the likelihood as well as the impacts of exceeding tipping points in the Earth system. Here we introduce the Tipping Point Modelling Intercomparison Project (TIPMIP, www.tipmip.org), a major international initiative setting out to fill this gap in a multi-model approach: Based on ensembles of simulations with Earth system models as well as offline models combined with current observations, the experiments will serve to assess (1) the risk of crossing critical thresholds in the Greenland and Antarctic ice sheets, the Atlantic Meridional Overturning Circulation, tropical and boreal forests as well as high-latitude permafrost; (2) the short- and long-term (committed) impacts of crossing individual tipping points; (3) the (ir)reversibility of impacts on different timescales; and (4) the role of the forcing rate. TIPMIP also sheds light on potential model shortcomings when it comes to such highly-nonlinear dynamics in the Earth system which may significantly change projections for the 21st century and beyond. The TIPMIP outcome will serve to generate a risk map, highlighting regions in the world which are most vulnerable to tipping transitions, which will be an important basis for forward-looking policy decisions. 
The Early Cretaceous to Miocene tectonic evolution of NW Cyclades based on 40Ar/39Ar multiple single crystal dating from Andros
Authors: Shang Shijie , Uunk Bertram , Kuiper Klaudia , Brouwer Fraukje , Wijbrans Jan
Published: March 2024

The Cycladic Archipelago in Greece preserves widespread evidence for high-pressure (HP) metamorphism and subduction and extension tectonics, during the evolution of a NE dipping subduction zone. How and at what rates various HP rocks were subducted and exhumed and how the associated complex deformation patterns originated remains controversial. We collected 26 samples from the Cycladic Blueschist Unit (CBU), the overlying Makrotantalon Unit (MU) and their contact zone on Andros for white mica single grain 40Ar/39Ar dating and combined the results with field and petrological observations to constrain the tectonic evolution of the NW Cyclades. To investigate the thermal state during tectonic evolution and the duration of deformation, we conducted 40Ar/39Ar multiple single crystal dating on different grain size fractions of white mica from the same sample.Our results show three distinct episodes of deformation:D0 is only locally preserved within the MU and the underlying contact zone and derives from the Early Cretaceous (128-119 Ma) Vardar ophiolite obduction above the Pelagonian margin, driving metamorphism and deformation of the passive margin. The white mica grains from the MU present Early Cretaceous ages of ~128 Ma (500-1000 mm) and ~117 Ma (120-250 mm). We suggest that the 11 Ma difference indicates a slower cooling rate.
D1 recorded in the contact zone and in the CBU, indicating that the CBU was exhumed along this contact zone from subduction depths during the Eocene (52-48 Ma). The white mica grains from the CBU present Eocene ages of ~52 Ma (500-1000 mm) and ~48 Ma (120-250 mm), with a gap of 4 Ma suggesting a faster cooling rate.
D2 is characterized by ductile-to-brittle deformation preserved in the contact zone and within the CBU, indicating they accommodated extension from around 28 Ma, with the initiation of slab rollback in the eastern Mediterranean. The contact zone between the MU and CBU exhumed greenschist-facies rocks of the CBU as a detachment until 21 Ma, when the rocks crossed the brittle-ductile transition and initiated brittle deformation, characterized by top-to-NE normal faulting.
We further redefine the structure of North Andros. In our study, we merge the MU and the ophiolites of the upper unit exposed in North Andros, previously thought to be separate units, in one unit equivalent of the Pelagonian unit. The contact between the MU and CBU, previously thought to be a thrust, is remapped as a brittle-ductile detachment fault between this one Pelagonian unit and the lower CBU and represents the NW extension of the Tinos, Mykonos detachments. This contact has accommodated syn-orogenic exhumation the CBU below the Pelagonian unit during Eocene HP metamorphism, and accommodated regional extension as part of the North Cycladic Detachment System during the Miocene.
From plot to catchment scale: evaluating historical and adapted land management practices in an agricultural watershed in Tajikistan
Authors: Konold Oliver , Benedek Cosima , Visintin Peter , Thier Maximilian , Stoisser Victoria , Stumpp Christine , Mehdi-Schulz Bano , Khudonazarov Faridun , Kassam Shinan , Aminov Sharif , Khojaev Davlatshoh , Khojaev Sharif , Haddad Mira , Akramkhanov Akmal , Strohmeier Stefan
Published: March 2024

Societal and agronomic changes during Tajikistan’s post-soviet era have altered the rural farmland management and the related catchment hydrology. The increasing demand for food production and the limited crop diversity eventually affected soil health and surface hydrological processes. Late planting of summer crops, the removal of plant residues and intense soil disturbance through ploughing are accompanied with limited rainfall interception, which fosters runoff and eventually erosion with potentially disastrous consequences in the downstream areas. As part of Caritas Switzerland's Weather, Water, Climate Services (WWCS) initiative, jointly funded with the Swiss Agency for Development and Cooperation, this study assesses the adoption of Sustainable Land Management (SLM) practices at the field level to reduce surface runoff and erosion, while diversifying and enhancing crop production. This study focuses on a 6356 km2 large watershed in the Khatlon region of Tajikistan and couples field experimental runoff plot monitoring with process-based hillslope scale modeling (Water Erosion Prediction Project; WEPP), eventually connected with watershed level hydrological assessment (Soil and Water Assessment Tool; SWAT). Field experimental procedures are being conducted through national, international and local citizen scientists. The study is in its initial phase – however, one season of plot monitoring has been conducted that allows a preliminary assessment of the surface runoff and erosion response of bare, summer wheat, chickpea, alfalfa and esparcet plots. The experiment enables the assessment of the single crops’ performances, as well as integrating crops into rotations through modeling. At the same time, land use and land cover (LULC) ground truthing within the Khatlon watershed was undertaken to validate two freely available global data products provided by the European Space Agency ESA; the CCI LC 300m and the ESA WorldCover 10m datasets. From the ESA CCI LC product, a comprehensive time series from 1992 to 2020 was developed to analyse the changes in LULC within the research area. The validation process enhances the reliability of the LULC data, which is also important for modelling purposes, in the Khatlon region. In a next step, involving multiple stakeholders, land suitability assessment and mapping will yield plausible watershed management scenarios to evaluate the potential of diversification and the introduction of multi-seasonal crops (i.e. alfalfa and esparcet) to reduce surface runoff and sediment yields from the farmlands and to strengthen the local agro-ecosystems and their sustainable production.
Magma storage quantified under Aluto volcano, Ethiopia, using probabilistic tomography
Authors: Roy Corinna , Nowacki Andy , Curtis Andrew , Baptie Brian
Published: March 2024

Rift volcanoes worldwide present significant hazards to people from eruptions but also provide resources such as geothermal energy. Aluto volcano in the Ethiopian rift is a hotspot for geothermal power exploitations, despite significant periods of deformation in the last 15 years. Various geophysical imaging methods have been applied to Aluto to obtain a detailed 3D image of the hydrothermal reservoir and the location, geometry, and size of possible magma bodies. However, the models give a single or narrow range of answers without the possibility for the exploration of uncertainties arising from the data and assumptions.Here we address this current limitation for the seismic data by performing a fully nonlinearized joint inversion of local seismic P- and S-wave travel times, and surface wave dispersion data between 0.5 Hz and 2 Hz from empirical Green's functions, for the location of earthquakes and the velocity of the subsurface. The combination of data types helps reduce the range of permitted models. We use a reversible-jump Markov chain Monte Carlo approach to incorporate prior information and, from our data, retrieve the posterior probability of earthquake parameters and seismic velocity in a Bayesian sense. This provides rigorous distributions of the covariance of the earthquake and velocity parameters.Our 3D seismic models display areas of elevated Vp/Vs ratio at 2-6 km depth under the caldera, interpreted as areas of partial melt. The hydrothermal reservoir shows in our results as lower Vp/Vs. This is in good agreement with the previous resistivity models from the magnetotelluric study of Samrock et al. 2020. However, while Samrock et al. observed two zones of partial melt, our model suggests that the lower and upper melt zones are connected. To go one step further, we developed a workflow to link seismic velocities to melt fraction estimates by combining the posterior distributions of seismic velocity and thermodynamic modeling. We conclude that the melt fraction under Aluto is between 3 and 7 % at 5 km depths, and the melt volume is approximately 0.37 km3.
Strengthening seasonal forecasting in the Middle East & North Africa (MENA) through the WISER Programme.
Authors: Lines Stefan , Savage Nicholas , Parfitt Rebecca , Colman Andrew , Chamberlain-Clay Alex , Norris Luke , Howard Heidi , Ticehurst Helen
Published: March 2024

In this presentation, we introduce the WISER MENA projects SeaFOAM (Seasonal Forecasting Across MENA) and SeaSCAPE (Seasonal Co-Production and Application in MENA). These projects explore both the improvement to the regional-level seasonal forecast in the MENA region, as well as how to tailor the information in ways useful to a range of climate information stakeholders. SeaFOAM works alongside Maroc Meteo, Morocco's National Meteorological and Hydrological Service (NMHS) and the Long Range Forecasting node of the Northern Africa WMO Regional Climate Centre (RCC), to develop a framework for objective seasonal forecasting. This approach will blend techniques such as bias correction via local linear regression and canonical correlation analysis (CCA), with skill-assessed sub-selected models, to improve forecasting accuracy. Multiple drivers of rainfall variability, including the North Atlantic Oscillation (NAO) and Mediterranean Oscillation (MO), are investigated for their calibration potential. SeaSCAPE works with the WMO and various partners across MENA to understand the use of seasonal information in multiple sectors, exploring existing gaps and needs. Through stakeholder engagement workshops, training and bespoke support for the Arab Climate Outlook Forum (ArabCOF), SeaSCAPE operates collaboratively to tailor regional and national-level climate information to improve accessibility and usability of climate information on seasonal timescales.
The role of the host climate model in quantifying the contrail cirrus climate impact
Authors: Zhang Weiyu , Rap Alexandru , Van Weverberg Kwinten , Furtado Kalli , Feng Wuhu , Morcrette Cyril , Forster Piers
Published: March 2024

Aviation currently makes a 3.5% contribution to the anthropogenic effective radiative forcing of climate. The largest component of this forcing comes from contrail cirrus, estimated to be 2 times larger than the contribution from aviation CO2 emissions. However, there is still a large uncertainty (i.e. ~70%) in the contrail cirrus effective radiative forcing (ERF) estimates according to the latest aviation climate impact assessment.Here we implement the existing contrail parameterisation developed for the Community Atmosphere Model version 6 (CAM6) in the atmospheric component of the UK Earth System Model (UKESM), i.e. the Unified Model (UM). By analysing and comparing the results from both models, we are able to isolate and investigate for the first time how key features of the host climate model is affecting our ability to accurately quantify the contrail climate impacts.We show that differences in background humidity (particularly ice supersaturation) in the two climate models lead to substantial differences in the simulated contrail fractions, with UM values being 2-3 times larger than those from CAM6. We also find contrasting responses in overall global cloud cover due to air traffic, with contrails causing increases and decreases in total cloud fraction in the UM and in CAM6, respectively. The different complexity of the two models’ cloud schemes (i.e. single and double moment cloud scheme in UM and CAM6, respectively) results in substantial differences in the simulated contrail-driven changes in cloud ice water content. However, if we account for this difference in cloud scheme complexity by scaling the simulated UM contrail cirrus optical depth to match existing estimates, the contrail cirrus ERFs simulated by the two models are comparable.To conclude, the large dependence of the simulated contrail cirrus climate impact on the host climate model highlights the need for improved evaluations of the key model microphysical and radiative processes.
Determining the englacial temperature evolution of very small glaciers in the Swiss Alps: An enthalpy-based modelling approach
Authors: Beer Janosch , Jacquemart Mylène , Utkin Ivan , Huss Matthias , Vieli Andreas , Farinotti Daniel
Published: March 2024

Despite constituting 80% of the total number of glaciers in mid- to low-mountain range catchments, the attention paid to very small glaciers (< 0.5 km2) in glacier research remains relatively low. However, glaciers of this size category are expected to undergo dramatic changes. Within Switzerland, more than half are predicted to disappear within the next two decades. As these glaciers shrink, they lose their firn cover, a crucial latent heat source through refreezing meltwater. Simultaneously, reduced glacier dynamics result in less ice deformation and decreased frictional heating at the base. Various studies suggest that such conditions can promote cooling, possibly enabling a transition from temperate to polythermal or cold states. Polythermal glaciers, especially those with partly frozen glacier beds, have been found to accumulate excessive meltwater, significantly increasing their hazard potential. In this study we present a new enthalpy-based englacial temperature model (IceT) to investigate the potential transition of very small Swiss glaciers from temperate to polythermal or cold conditions. The study focuses on identifying key parameters influencing glacier thermal transitions through a sensitivity analysis. Furthermore, we apply the model on a subset of 20 very small Swiss glaciers and compare our findings against previously generated model results of the Glacier Evolution Runoff Model (GERM). Our results indicate that mass balance and the liquid water content are the most significant factors for predicting glacier thermal states. The influence of mass balance works in two ways: (1) Highly negative mass balances hinder the development of a polythermal structure by allowing surface melt to surpass the propagation of the cold-temperate transition surface (CTS). (2) Less negative mass balances combined with limited snowfall, induce a transition to polythermal conditions by enabling the CTS propagation to outpace surface melt. Ultimately, the liquid water content (φ) appears as the most critical parameter in predicting ice temperatures. A mere increase of φ by 1% could reduce the maximum CTS depth by 165.07 m and lower the annual CTS propagation rate by 13.85 m a-1. Significant differences emerge between GERM and IceT findings. GERM suggests that the majority of all very small Swiss glaciers exhibit polythermal conditions, while in the subset of 20 glaciers modeled with IceT, only 15% show indications of a polythermal regime. However, the considerable impact of liquid water on predicting ice temperatures, coupled with the incomplete knowledge regarding its distribution within glaciers, leads to substantial uncertainties in the presented model outcomes.
Toward using δ2H values for investigating marine mixotrophy
Authors: Cormier Marc-Andre , Berard Jean-Baptiste , Nelson Daniel , Flynn Kevin , Lampitt Richard , Bougaran Gael
Published: March 2024

Hydrogen isotope ratios (δ2H) measured on lipids extracted from aquatic and terrestrial organisms are widely applied for studying past hydro-climatic conditions. A growing body of evidence suggests that δ2H values of lipids integrate not only climatic, but also metabolic information. Metabolic effects hinder the reconstruction of climatic conditions based on δ2H values from archives and urges for a better understanding of the key drivers of δ2H values in organic compounds. Once disentangled, such non-climatic information in δ2H values may become key for investigating misunderstood eco-physiological behaviours. One such behaviour is marine mixotrophy.While science requires tools to measure the contributions of phototrophic and heterotrophic growth in plankton, my colleagues and I have already shown that lipid δ2H values are uniquely sensitive to the expression of heterotrophy relative to photosynthesis in plants. This presentation will discuss groundwork experiments performed with chlorophytes and dinoflagellates exploring whether δ2H values of diverse compounds produced by protists are similarly sensitive to their central metabolic pathway. New δ2H analyses performed on fatty acids, phytols and sterols from these experiments, using an isotope ratio mass spectrometer (IRMS) coupled to a gas chromatograph (GC), will be discussed. Our data suggest that lipids δ2H values are indeed sensitive to the level of heterotrophic growth in diverse protists.If this relation can be confirmed and calibrated, compound specific H isotope analyses could provide a powerful means to study the role of mixotrophy on the global carbon cycle and the occurrences of HABs.
Aggregations of parametrizations and machine learning for gravity wave momentum flux reconstruction
Authors: Has Sothea
Published: March 2024

In this talk, we pursue the investigation of the relation between the large-scale flows and observed gravity wave momentum fluxes (GWMFs), starting from parameterizations and machine learning as two alternatives for predicting the gravity wave momentum fluxes in the lowermost tropical stratosphere. We investigate how much aggregation methods may allow to further improve on both alternatives, and what complementarity there may be between them. Observed gravity wave momentum fluxes are obtained from superpressure balloons during the Strateole 2 mission. The parameterizations come from the different climate models involved in the QBOi project, that have been compared to balloon measurements in Lott et al. (2023). The other predicted features are three tree-based ensemble machine learning algorithms, trained on part of the Strateole 2 dataset.  Three groups of aggregations are performed: aggregation among machine learning models, aggregation among parametrizations, and the aggregation between parametrizations and machine learning models. For the methodology, three aggregation methods are employed; two methods treat predictions from different models (parametrizations or machine learning) as features or information to be aggregated, while the remaining one uses both, inputs and predictions provided by those models.The outcomes indicate that, despite struggling to estimate GWMFs individually, the collective information from various parametrizations proves valuable, particularly when combined with the large-scale flow variables. Additionally, the performance of the aggregation methods is sensitive to the choice of balloons. When the description of large-scale flows aligns well with the target GWMFs (balloon 2 and 8), all aggregation methods perform just as well as machine learning or the best-case scenario of parametrizations. Interestingly, there are also a few cases where machine learning and parametrizations perform poorly (correlation less than 0.2), yet their predictions, combined with large-scale information, can significantly elevate their performances more than 2 times (correlation larger than 0.5) in the aggregation methods (balloon 5). This suggests that existing parameterizations and machine learning approaches trained on observations have a complementarity that remains to be exploited. The present study was entirely offline, with no issue about the costs of computation. For practical applications, further investigation will be required to narrow down on the specific elements of parameterizations that are most informative.
MOSEP: A Multi-Sensor Platform for Environmental Monitoring: Bridging the Scale Gap in Precipitation Measurement
Authors: Gaisberger Christoph , Muckenhuber Stefan , Schöner Wolfgang , Schlager Birgit , Gölles Thomas , Schrei Benjamin
Published: March 2024

The cryosphere's dynamic processes, from snow accumulation and avalanche activity to glacier calving, demand innovative monitoring solutions that offer both high spatial and temporal resolution. Current advancements in sensor technology are revolutionizing environmental monitoring. Our research introduces MOSEP (Modular Multi-Sensor System for Environment Perception), a novel, adaptable multi-sensor platform employing sensors traditionally used in autonomous vehicles, repurposed for environmental monitoring. This system integrates lidar, camera, radar, and a weather station powered by a Raspberry Pi 4 and equipped with open-source software for detailed environmental analysis. Previously utilized for mapping applications with automotive lidar, GPS, and an IMU, our platform has been enhanced with additional sensors to complement the lidar, notably radar and camera. The automotive sensors' high temporal resolution enables the observation of rapid environmental changes, offering an affordable and effective alternative to traditional geophysical sensors like TLS, particularly with the additional benefits of sensor fusion.In cryospheric applications, the camera, radar, and lidar can work together to monitor surface changes, snow depth, accumulation rates, and potentially detect avalanches or other mass movements. The platform's flexibility and mobility are particularly advantageous for studying small-scale features and processes that are otherwise difficult to capture with satellite methods due to their coarse resolution and infrequent revisit times. While we have shown that lidar-based mapping using SLAM algorithms is effective, current research focuses on sensor performance in adverse weather conditions and the capability to detect and quantify weather effects. Traditional precipitation measurements face a 'scale gap,' with satellite and weather radar observations offering extensive spatial coverage at low resolution and rain gauges providing high accuracy at specific locations. Automotive sensor and specifically lidar could help bridge this gap especially in complex terrain. The inclusion of a camera assists in differentiating meteorological phenomena, such as rain from snowfall. However, the 'black box' nature of automotive sensors also present challenges. A measurement campaign was conducted last fall, and this contribution will present preliminary results alongside an overview of the latest hardware and software enhancements.By introducing the novel use of easily accessible automotive sensors for environmental monitoring, our work contributes to the evolving field of cryospheric research, emphasizing the potential for cross-disciplinary innovation and the development of scalable, cost-effective environmental sensing networks.
Monitoring Anthropogenic Irrigation Water Use by assimilating satellite land surface temperature and soil moisture
Authors: Corbari Chiara , Paciolla Nicola , Dos Santos Araujo Diego Cezar , Labbassi Kamal , Sheffield Justin , Berendsen Sven , Al Bitar Ahmad , Szantoi Zoltan
Published: March 2024

The agricultural sector is the biggest and least efficient water user, accounting for around 80% of total water use in Northern Africa, which is already strongly impacted by climate change with prolonged drought periods, imposing limitation to irrigation water availability. The objective of this study was to develop a procedure for the monitoring of anthropogenic irrigation water use for the irrigation districts of Doukkala in Morocco, from 2013 to 2022.The system is based on the energy-water balance model FEST-EWB, which is an agro-hydrologic pixel wise model that computes continuously in time the main processes of the hydrological cycle where evapotranspiration and soil moisture behaviour in agricultural soil layer are modelled solving the energy and water mass balance model (EWB).Firstly, the model has been calibrated and validated over non-irrigated areas, against satellite land surface temperature from LANDSAT and downscaled Sentinel3 data at 30m of spatial resolution, and evapotranspiration from MOD16, GLEAM and FAOWapor. The model has been run using as input the past observed meteorological forcings (ECMWF ERA5-Land) and vegetation data. From the pixel-by-pixel comparison between modelled and observed LST, a mean absolute difference of 3.5 °C is obtained over the period 2017-2022 for the whole Doukkala area.The second step refers to the historical estimates of the actual irrigation volumes through the calibrated model implementing three different irrigation strategy, at hourly scale and at 30m of spatial resolution: the FAO approach based on soil moisture (SM) and crop stress thresholds (Allen et al., 1998), the separate and joint assimilation of satellite land surface temperature (downscaled Sentinel3 data) and of satellite soil moisture (1km SMAP-Sentinel1) to update the modeled fluxes and estimates irrigation volume. Overall, the results suggested that the yearly total irrigation volumes modeled with the FAO approach are quite in agreement with the observed water allocations; and similar outcomes are obtained when the joint assimilation of satellite LST and SM is implemented which allows to overcome the problems related to the number of available satellite images, which could lead to missing irrigation events.