bluuebunny/crossref_metadata_2025 huggingface dataset:
Global Warming Determines Future Increase in Compound Dry and Hot Days within Wheat Growing Seasons Worldwide
Authors: He Yan , Zhao Yanxia , Duan Yihong , Hu Xiaokang , Shi Peijun
Published: March 2024

Compound dry and hot extremes are proved to be the most damaging climatic stressor to wheat thereby with grave implications for food security, thus it is critical to systematically reveal their changes under unabated global warming. This study provides a comprehensive analysis of the changes in compound dry and hot days (CDHD) occurring within dynamic wheat growing seasons of 2015-2100 over dynamic wheat planting regions worldwide under SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5, including CDHD’s frequency and severity. This study sought to fill the gap in knowledge by identifying the CDHD occurring within dynamic wheat growing seasons, clarifying the correlations between droughts and heats as well as their impacts on CDHD, and revealing the driven mechanism of global warming for the increase of CDHD.Our results demonstrate a notable increase in CDHD’s frequency and severity worldwide under all SSPs, such increase is sharper over southern Asia in winter wheat growing season, and southern Canada, northern America, Ukraine, Turkey and northern Kazakhstan in spring wheat growing season. As the top 10 wheat producer, India and America will suffer much more detrimental CDHD in their wheat growing season. Adopting a low forcing pathway will mitigate CDHD risks in up to 93.3% of wheat areas. Positive dependence between droughts and heats in wheat growing season is found over more than 74.2% of wheat areas, which will effectively promote the frequency and severity of CDHD. Global warming will dominate the increase of CDHD directly by increasing hot days and indirectly by enhancing potential evapotranspiration thereby aggravating droughts. This study helps to optimize adaptation strategies for mitigating CDHD risks on wheat production, and provides new insights and analysis paradigm for investigating future variations in compound extremes occurring within dynamic crops growing seasons.
Struggling with climate changes
Authors: Damjanoska Karolina
Published: March 2024

STRUGGLING WITH CLIMATE CHANGES Karolina DamjanoskaMaster of Science in Physics Education and Physics Teacher in High School “Orde Chopela”,Prilep, North Macedonia. e-mail: kdamjanoska08@gmail.comMy students from SOU "Orde Chopela" have participated in many projects as citizen scientists,such as the Globe at night project, which has been going on for sixteen years. The project isenables students to do light pollution measurements by observing diverse constellations in thenight sky. That way, they get educated about the importance of maintaining a healthyenvironment as well as the human impact on a changing climate. Over the years, I have gotten asignificant experience in the field and my students have achieved excellent results in domesticand international competitions, which has motivated me to continue passing on my knowledge tocolleagues in my country and abroad.For many years, I have been a leader and SOU "Orde Chopela" school coordinator for theGLOBE project. Additionally, I am an official trainer for the GLOBE project and its Atmosphereprotocol. Measurements made during this protocol closely relate to those in the GLOBE project,due to the importance of the visibility of the night sky. Besides that, while implementing theproject, the students have had the chance to delve into taking care and contributing to a healthyenvironment.Active participation in projects like these, give the students a chance to be properly formed asindividuals who advocate for a healthy environment and are able to think and act appropriately.Their awareness of preserving the environment is at a very high level, they work on authenticproblems for which they seek and find solutions. Ultimately, the goal is contributing to thecommon good.
Impact of road network expansion on landscape ecological risk and soil erosion sensitivity on the Luochuan Tableland of the Chinese Loess Plateau
Authors: Yang Siqi , Jin Zhao
Published: March 2024

Road construction efforts have significantly increased in developing countries in recent decades. While expanding road networks have promoted economic development, it may result in the fragmentation of ecological landscapes and an increased risk of soil erosion. However, knowledge about these consequences is limited. This study aimed to characterize the expansion of the road network, landscape ecological risk, and soil erosion sensitivity on the Luochuan tableland of the Chinese Loess Plateau from 1990 to 2020. In this study, the landscape ecological risk refers to the spatial and temporal heterogeneity within a region, as well as the scale effect and the impact of landscape pattern fragmentation on regional ecological risk. The results of this study showed that 1) the road network on the Luochuan tableland has significantly expanded over the past 30 years, and the proportion of areas with high road density (kernel density value > 120 km/km2) increased from 10.13% to 37.18% of the total area between 1990 and 2020. 2) The landscape ecological risk was the highest in 2005; from 1990 to 2005, the land area with extra-high landscape ecological risk increased from 0 to 13.30 km2 and then decreased to 0 in 2020. 3) Similar to the variations in landscape ecological risk, the soil sensitivity was severe in 2005 on the Luochuan tableland. 4) Areas with a higher landscape ecological risk were mainly concentrated in areas of high road density. The road kernel density was significantly and positively correlated with landscape ecological risk and soil erosion sensitivity (P < 0.01). This study could help to understand the potential impact of road network expansion on landscape ecological risk and soil erosion at a regional scale.
Effects of climate and land use on water balance and water quality in selected European lakes
Authors: Mercado Ma Cristina , Rabaneda-Bueno Ruben , Porcal Petr , Kopacek Marek , Huneau Frederic , Vystavna Yuliya
Published: March 2024

Lakes, natural or artificial, are important sources of freshwater and are frequently managed to provide ecosystem services. Consequently, the water balance and water quality in lake ecosystems could be subject to different stressors associated to physical, chemical, or anthropogenic activities. Therefore, this study provides insights into the factors that influence the water balance of selected European lakes and their implications on water quality. An analysis of isotopic, chemical, and land use data using statistical and artificial intelligence models showed that climate, in particular air temperature and precipitation, played a key role in intensifying evaporation losses from lakes. Groundwater table depth and other catchment factors also had an impact on the water balance. The study also highlights that lakes at lower altitudes with shallow depths and catchments dominated by urban or crop cover were more sensitive to water balance changes. These lakes had higher evaporation-to-inflow ratios and increased levels of total nitrogen concentration in the water. However, lakes at higher elevations with deeper depths and a predominantly forested catchment area are less sensitive to changes in the water balance. These lakes, which are often of glacial origin, were characterized by lower evaporation losses and, thus, better water quality in terms of total nitrogen concentration. Overall, understanding the relationship between water balance and water quality is crucial for effective lake management and the preservation of freshwater ecosystems.
Geophysical responses to an environmentally-boosted volcanic unrest
Authors: De Siena Luca , Amoruso Antonella , Petrosino Simona , Crescentini Luca
Published: March 2024

Campi Flegrei caldera, one of the most dangerous volcanoes in the world, is experiencing the strongest seismic and deformation unrest of the last 40 years. Geophysical, environmental, and geochemical responses during volcanic unrest at any volcano are difficult to couple: this is especially true at a caldera where deformation signals and earthquakes are attributed to magma and fluid/rock interactions at depths as well as tidal and meteoric forcing at the surface. Here, we applied Empirical Orthogonal Functions analysis, a technique developed within climatic and environmental Sciences, to GPS data. The technique allows the spatiotemporal separation of the dominant deep-sourced inflation from environmentally controlled signals associated with extension at Campi Flegrei caldera. This separation bridges the gap between deformation, seismic and geochemical responses, clarifying the processes that started the ongoing volcanic unrest. Persistent meteoric forcing during the 2017-18 hydrological year, located in the middle of a five-year drought, changed the decadal trend of seismic energy and secondary deformation components, pairing their spatial patterns. The result was a block in the carbon dioxide released in 2018 at Solfatara, the primary stress-release valve at the caldera. The subsequent overpressure weakened the fractured eastern caldera, opening pathways for hot materials produced by the dominant deep deformation source to reach the surface. Our results show how environmental forcing can favour volcanic unrest in pressurised calderas.
Sustainable Management of Golf Courses in Hanoi City: A Remote Sensing Approach for Monitoring Land Distribution and Dynamics
Authors: Nguyen Kim-Anh , Liou Yuei - An , Luong Minh Khanh , Hoan Nguyen Thanh
Published: March 2024

In recent years, the role of golf courses in contributing to the economic growth of various Vietnamese cities, including Hanoi, has gained prominence. Nonetheless, debates persist regarding the environmental and societal impacts of golf course development. While golf courses enhance city aesthetics, attract affluent tourists, and align with zero-carbon initiatives, concerns arise over land use, pesticide application, water resources, farmer displacement, and potential environmental degradation.This study employs remote sensing data to monitor the spatial and temporal distribution of golf courses in the Hanoi City Metropolitan area. Utilizing multi-satellite data and Geographic Information Systems (GIS), the research aims to detect and analyze the spatial dynamics of golf courses, investigating their evolution and impact on the surrounding regions. The outcomes include a remote sensing-based database of golf courses, an examination of dynamic changes in golf course lands over decades, and an assessment of land conversion to golf courses and its consequences. This research is crucial for sustainable golf course management and environmental conservation, providing insights for informed decision-making to achieve environmental sustainability in golf course development.
A Punctuated Equilibrium Analysis of the Climate Evolution of Cenozoic exhibits a Hierarchy of Abrupt Transitions
Authors: Rousseau Denis-Didier , Bagniewski Witold , Lucarini Valerio
Published: March 2024

The Earth’s climate has experienced numerous critical transitions during its history, which have often been accompanied by massive and rapid changes in the biosphere. Such transitions are evidenced in various proxy records covering different timescales. The goal is then to identify, date, characterize, and rank past critical transitions in terms of importance, thus possibly yielding a more thorough perspective on climatic history. To illustrate such an approach, which is inspired by the punctuated equilibrium perspective on the theory of evolution, we have analyzed 2 key high-resolution datasets: the CENOGRID marine compilation (past 66 Myr), and North Atlantic U1308 record (past 3.3 Myr). By combining recurrence analysis of the individual time series with a multivariate representation of the system based on the theory of the quasi-potential, we identify the key abrupt transitions associated with major regime changes that separate various clusters of climate variability. This allows interpreting the time-evolution of the system as a trajectory taking place in a dynamical landscape, whose multiscale features describe a hierarchy of metastable states and associated tipping points.The analysis reveals that two major events out of the ten dominated the evolution of the Earth's climate system over the last 66 million years. The first event was the Chicxulub meteor impact in Mexico, which killed off the large dinosaurs approximately 65,5 million years ago. This catastrophe marked the beginning of a very warm period with high levels of CO2. For the following 30 million years this regime dictated which climatic changes were possible and kept it within the regime of hot and warm climates.The second crucial event was the tipping point associated with the glaciation of the Southern hemisphere 34 million years ago when the Antarctic continent was isolated at the South Pole due to plate tectonics. The forming of the large ice sheet led to the glaciation of the North as well and marked the beginning of a considerably colder type of climate on Earth, again dictating the scope of future climate changes.The analysis additionally suggests that our current global climate system still belongs to the latter climate regime and still depends on the existence of the gigantic ice bodies built within the Coolhouse/Icehouse era. In the event that the ice sheets should not withstand anthropogenic global warming, the deglaciation will therefore represent a landmark tipping point similar to the two that have dominated Earth's history leading to a new unknown climate landscape.Rousseau, DD., Bagniewski, W. & Lucarini, V. A punctuated equilibrium analysis of the climate evolution of cenozoic exhibits a hierarchy of abrupt transitions. Sci Rep 13, 11290 (2023). doi: 10.1038/s41598-023-38454-
Revealing long-term changes in the North Atlantic air-sea fluxes from provisionally corrected VOS observations (1900-2022)
Authors: Gulev Sergey , Aleksandrova Marina
Published: March 2024

We use Voluntary Observing Ship (VOS) observations available form the ICOADS collection for estimating surface fluxes in the North Atlantic for the period from 1900-2022. One problem of the use of VOS observations for deriving long-term air-sea flux time series is associated with inhomogeneous in space and time sampling, especially during the period prior WW2. Another problem is associated with systematic biases in a number of VOS state variables (first of all cloud cover) for the first part of 20th century. To derive surface flux anomalies we first reconstruct turbulent heat fluxes from 1900 onwards for the whole North Atlantic from EQ to 70 N. To homogenize sampling density and obtaine more robust estimates we use the procedure of sub-sampling for the earlier decades and then integrate computed turbulent heat fluxes in the coordinates of steering parameters (vertical surface temperature and humidity gradients on one hand and wind speed on the other). Biases in cloud cover are associated with changes in the observational practices of in the early 1950s when WMO implemented new standardized coding system. These biases have the effect of systematic underestimation of total cloud cover during 1900-1940 compared to the past WW2 period ranging from 0.3 to 1 octa and imply biases in short- and long-wave radiation of up to 10 W/m2 and 4 W/m2 respectively. We explored all sources of these biases using direct analysis of early 20th century log-books and performed correction of cloud cover using cloud cover probability density functions. Then short- and long-wave radiative fluxes were computed using state of the art bulk parameterizations. Thus, we obtained long-term time series of turbulent heat fluxes and radiative fluxes for 120-yr period 1900-2022. Analysis of centennial trends shows upward change in sensible plus latent flux ranging from 3 to 14 W/m2 during 120 years, while the increase over the last 40 years amounts to 6-7 W/m2 with the major growth during the 1990s and early 2000s. Radiative fluxes demonstrated increase in short-wave radiation (positive directed to the ocean) of 3-5 W/m2 in the Atlantic subtropics and mid latitudes and weak or close to zero trends in long-wave radiation. While changes in radiative fluxes partially compensate opposite trends in turbulent fluxes, the upward tendency in ocean heat budget (atmosphere gains) remains significant with magnitude of 2-6 W/m2 over 120-yr period. Interdecadal variability of surface turbulent fluxes is of an order of magnitude stronger compared to the radiative fluxes (10-20 W/m2 vs 0.5-2 W/m2), thus implying the dominant role of turbulent fluxes on forming long-term changes of the ocean heat budget. Further interdecadal variability of surface heat budget is discussed in the context of the North Atlantic multidecadal variations.Research is funded by RSF project # 23-47-00030.
Future global water scarcity including quality under climate and socioeconomic change
Authors: Jones Edward R. , Bierkens Marc F.P. , van Vliet Michelle T.H.
Published: March 2024

Inadequate availability of clean water presents systemic risks to human health, food production, energy generation and ecosystem functioning. While future alterations to water demands and availability are widely projected to exacerbate water scarcity, the impact of changing water quality is largely unknown. Leveraging a newly-developed global surface water quality model (DynQual1) which is coupled to a global hydrological model (PCR-GLOBWB2), we make the first projections of future global water scarcity including both water quantity and quality aspects.We consider three combined RCP-SSP scenarios (SSP1-RCP2.6, SSP3-RCP7.0 and SSP5-RCP8.5), each of which simulated with bias-corrected CMIP6 climate input from five GCMs provided within ISIMIP3b, to encompass a range of possible future conditions and to capture uncertainty inherent in the climatological (GCM) projections. Simulated monthly sectoral water demands (domestic, industrial, livestock and irrigation), water availability (e.g. discharge) and water quality (total dissolved solids, biological oxygen demand and fecal coliform) for 2005-21002 are used as basis for quantifying clean water scarcity, which we express in terms of population exposure.We find that 57% of the global population (~4 billion people) are currently exposed to clean water scarcity at least one month per year, increasing to 58 – 68% by the end of the century based on different plausible scenarios for climate change and socioeconomic development. Increases in exposure are largest in developing countries – particularly in Sub-Saharan Africa – driven by a combination of water quantity and quality issues. Strong reductions in both human water use and pollution are therefore necessary to minimise the impact of future water scarcity on humans and the environment. References1 Jones, E.R., M.F.P. Bierkens, N. Wanders, E.H. Sutanudjaja, L.P.H. van Beek,  M.T.H. van Vliet (2023), DynQual v1.0: A high-resolution global surface water quality model, Geosci. Model Dev., 16, 4481–4500, https://doi.org/10.5194/gmd-16-4481-20232 Jones, E.R., M.F.P. Bierkens, P.J.T.M. van Puijenbroek, L.P.H. van Beek, N. Wanders, E.H. Sutanudjaja, M.T.H. van Vliet (2023) Sub-Saharan Africa will increasingly become the dominant hotspot of surface water pollution, Nature Water, 1, 602–613, https://doi.org/10.1038/s44221-023-00105-5
On the Hermean near-planet boundaries response under different orbital interplanetary conditions
Authors: Cazzola Emanuele , Fontaine Dominique , Modolo Ronan
Published: March 2024

This work aimed to study the dynamical response of the near-Mercury environment to different interplanetary conditions experienced along its orbit by means of 3D multi-species hybrid simulations.Mercury features an eccentric and rapid orbit around the Sun, with its extreme aphelion (0.47 AU) and perihelion (0.31 AU) positions being embedded in significantly different interplanetary conditions. Given the different environments and its weak magnetic field strength, the position, size and behavior of the bow-shock, magnetosheath and magnetopause can vary significantly as highly coupled with the interplanetary medium. In this work, we consider an interplanetary magnetic field aligned along the Parker spiral direction at the Mercury's distance from the Sun, i.e., quasi-radial, and the case of an interaction with slow and fast solar winds. We show the response of the bow-shock due to such quasi-radial interplanetary field and the compression of the bow-shock / magnetosheath /  magnetopause system as the planet passes from the aphelion to perihelion orbital points, as well as the solar wind velocity increases. In particular, certain portions of the planet no longer present a significant protection from the interplanetary environment, so that the surface is exposed to the precipitation of interplanetary ions. An analysis of their fluxes revealed that the high latitude polar cusps are still the main regions for the interplanetary particles to reach out the surface. However, when the interplanetary conditions are sharp enough to cause a strong bow-shock and magnetosheath compression, the interplanetary particles are able to directly penetrate these boundaries and can precipitate at much lower latitudes. These results are particularly timely for the BepiColombo mission, and are compared with its first fly-bys observations.
Are multi-decadal sea-level oscillations augmenting rates of mean sea level?
Authors: Robson Erin , Jackson Luke , Williams Sophie
Published: March 2024

There is evidence to show sea-level change is accelerating, with a departure from Holocene rates in the late-19th century, to more than a doubling of the rate of global mean sea-level change over the past 25-years. Although the effect of anthropogenic forcing on sea level is certain, the influence of natural internal variability on augmenting rates of change remains an important area of research. This is especially significant at ocean-climate response timescales (>30-years). Using tide-gauge data, we apply empirical mode decomposition (EMD) to separate both the global and regional sea-level records into a series of intrinsic mode functions (IMFs) that are quasi-periodic in character. From them, we identify the dominant modes of variability that are common to each ocean basin, and compare these to recognised modes of climate variability to determine the causal factors of sea-level oscillations. We also conduct a sensitivity analysis with sub-sampled tide-gauge data to test the feasibility of this approach with high-resolution proxy-based sea-level reconstructions.
A glimpse into the future: The 2023 temperature extremes in the North Atlantic in the context of longer-term climate change
Authors: Kuhlbrodt Till , Swaminathan Ranjini , Ceppi Paulo , Wilder Thomas
Published: March 2024

In the year 2023, we have seen extraordinary extrema in high sea-surface temperature (SST) in the North Atlantic which are outside the 4-sigma envelope of the 1982-2011 daily timeseries. Here we take a first look at the large-scale, longer-term drivers of these extrema. Earth’s net global energy imbalance (in the 12 months up to September 2023) amounts to +1.9 W/m2 as part of a remarkably large upward trend, ensuring continuous heating of the ocean. However, the regional radiation budget over the North Atlantic does not show signs of a significant step increase from less negative aerosol forcing since 2020 as was suggested elsewhere. While the temperature in the top 100 m of the global ocean has been rising in all basins since about 1980, specifically the Atlantic basin has continued to further heat up since 2016. Similarly, salinity in the top 100 m of the ocean has increased in recent years specifically in the Atlantic basin. Outside the North Atlantic, around 2015 a substantial negative trend for sea-ice extent in the Southern Ocean has begun, leading to record low sea-ice extent in 2023. We suggest analysing the 2023 temperature extremes in the North Atlantic in the context of these recent global-scale ocean changes. Analysing climate and Earth System model simulations of the future, we find that the extreme SST in the North Atlantic and the extreme in Southern Ocean sea-ice extent in 2023 lie at the fringe of the expected mean climate change for a global surface-air temperature warming level (GWL) of 1.5°C, and closer to the average at a 3.0°C GWL. Understanding the regional and global drivers of these extremes is indispensable for assessing frequency and impacts of similar events in the coming years.
Quantification of landslide-induced changes in glacier dynamics – project outline
Authors: Bhattacharyya Arunabh , Ewertowski Marek , Małecki Jakub , Domej Gisela
Published: March 2024

The response of glacial masses to climate change is well documented. However, the impact of landslides on glacier dynamics and stability requires greater research. Landslides in glacierized mountains can be caused by climate change (e.g. permafrost thawing), intense precipitation, paraglacial response of slopes or earthquakes and can, in turn, limit ablation, increase meltwater production and alter glacier velocities. Besides, landslides can be hazardous to life and infrastructure. Permafrost degradation, de-buttressing of slopes, extreme precipitation and freezing and thawing cycles make mountain glaciers susceptible to instability and cascading hazards. Our project thus focuses on identifying the research gaps associated with landslide-glacier dynamics and related hazards. The two components of our project are 1) Remote sensing and GIS and 2) Modelling. Different spatial scales (landform, catchment, global) will be considered for our research.This presentation aims to outline PhD project and discuss proposed approaches with the glaciological, geomorphological, and remote sensing community. A literature review aimed at generating an inventory of landslide-affected glaciers globally is the first step. This will be complemented by detailed analyses and quantification of landslide-induced changes in glaciers’ behaviour by selecting benchmark case studies across different glacial systems representing different environmental conditions. Acquiring UAV data (0.05-0.10 m), high resolution (0.3-1.0 m) (Pleiades, WorldView, etc.), and medium resolution (10-50 m) satellite imagery (Landsat, Sentinel, Aster) will be essential for the quantification of changes in glaciers velocity and mass balance. We also plan field visits to benchmark glaciers to ground-truth remote sensing data and collect information about sedimentological and geomorphological characteristics of landslide deposits.This research was funded by the National Science Centre, Poland, project number 2021/42/E/ST10/0018
Microbial and mineral interactions decouple litter quality from soil organic matter formation 
Authors: Whitaker Jeanette , Mason Kelly , Taylor Ashley , Zhao Pengzhi , Goodall Tim , Griffiths Rob , McNamara Niall , Elias Dafydd
Published: March 2024

Mineral-associated organic matter (MAOM) forms from plant or microbial-derived compounds and comprises the largest reservoir of soil organic carbon (SOC) globally.  Most SOC is associated with soil minerals and mineralogy is considered a primary control on SOC persistence due to variations in mineral reactivity. However, most mineral-associated SOC is microbial in origin thus microbial residue formation, through the processing of plant inputs, may also control SOC dynamics. Current understanding suggests that litter quality controls the formation of MAOM with high-quality litter producing more microbial residues which are then stabilised on mineral surfaces. We hypothesized that inputs of high-quality litter would lead to a net increase in MAOM stocks, relative to low-quality litter, through more efficient formation of MAOM and less priming of existing SOC.  We also hypothesised that soil mineralogy would act as the primary control on the formation of MAOM relative to litter quality. To test our hypotheses, we amended an agricultural soil with common soil minerals (Kaolinite, Montmorillonite and unamended control) and incubated these amended soils in the laboratory with two surface-applied 13C labelled litters of contrasting qualities (high quality - White Clover and low quality - Winter Wheat). During the incubation, litter decomposition and priming were quantified by δ13CO2 analysis. After 4 months, mineral stabilisation of litter-C, the amounts of particulate organic matter (POM) remaining and litter-C assimilated into microbial biomass were all quantified, along with characterisation of the soil microbial communities. Soil mineralogy strongly influenced the efficiency of MAOM formation, with Montmorillonite-amended soils respiring less litter-C and stabilising more as MAOM. High quality litter led to less (not more) efficient production of MAOM due to soil microbial community shifts associated with lower carbon-use efficiency. Low-quality litter enhanced priming of pre-existing SOC, counterbalancing the effect of litter quality on MAOM stocks.  Taken together, our findings demonstrate that soil mineralogy was the primary control on MAOM formation and that litter-microbial interactions determine the effect of litter quality on MAOM.  These findings refute the hypothesis that high-quality plant litters form MAOM most efficiently and demonstrate that mineral and microbial interactions regulate the formation of stable SOC.
  Prandtl Number Effects on Extreme Mixing Events in Forced Stratified Turbulence
Authors: Caulfield Colm-cille P. , Petropoulos Nicoloas , Couchman Miles M. P. , de Bruyn Kops Steve , Mashayek Ali
Published: March 2024

`Strongly' stratified turbulent flows can self-organise into a  `layered anisotropic stratified turbulence' (LAST) regime, characterised by relatively deep and well-mixed density `layers' separated by relatively thin `interfaces' of enhanced density gradient. Understanding the associated mixing dynamics is important for parameterising heat transport in the world's oceans. It is challenging to study `LAST' mixing, as it is associated with Reynolds numbers Re := UL/ν  >> 1 and Froude numbers Fr :=(2πU)/(L N)  > 1 where ε is the TKE dissipation rate. This requirement is exacerbated for oceanically relevant flows, as the Prandtl number Pr := ν /κ = O(10) in thermally-stratified water (where κ is the thermal diffusivity), thus leading (potentially) to even finer density field structures. We report here on four forced fully resolved direct numerical simulations of stratified turbulence at various Froude (Fr=0.5, 2) and Prandtl numbers (Pr=1, 7) forced so that Reb=50, with resolutions up to 30240 x 30240 x 3780. We find that, as Pr increases, emergent `interfaces' become finer and their contribution to bulk mixing characteristics decreases at the expense of the small-scale density structures populating the well-mixed `layers'. Nevertheless, `extreme' mixing events (with elevated local destruction rates of buoyancy variance χ0 dominating the total mixing budget) are still preferentially found in strongly stratified interfaces, which has significant implications for parameterising  diapycnal mixing in larger scale ocean models. This project received funding from the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Grant Agreement No. 956457 and used resources of the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC05-00OR22725. S.deB.K. was supported under U.S. Office of Naval Research Grant number N00014-19-1-2152.
Nutrient limitation in soils regulate the effects of elevated CO2 on soil N cycling at BIFoR-FACE (UK) and Euc-FACE (Australia)
Authors: Rumeau Manon , Carrillo Yolima , Sgouridis Fotis , Mackenzie Rob , Reay Michaela , Ullah Sami
Published: March 2024

Increasing atmospheric CO2 concentrations due to human activities, is projected to enhance photosynthesis and carbon storage of forest ecosystem. However, it is unclear how nutrient limitation will constrain the projected CO2 fertilization effect. Therefore, it is essential to evaluate how nutrient limitation will affect the response of forests to rising CO2 concentration and how it will feedback on nutrient availabilities and more especially nitrogen (N) which can become limiting with time.The purpose of this research is to evaluate the response of N cycling processes to elevated CO2 enrichment in a N-limited northern deciduous temperate forest in the UK and a phosphorus (P)-limited Eucalyptus dominated forest in Australia. The research was conducted in two Free Air Carbon Dioxide Enrichment (FACE) facilities: BIFOR FACE located near Birmingham, UK and EucFACE in New South Wales, Australia. Furthermore, EucFACE (P-limited forest) received partial phosphorus fertilization to study its effect on N cycling.We employed a 15N pool dilution method to assess gross protein depolymerization and gross mineralization at both study sites, along with the measurement of nitrous oxide emissions, extracellular soil enzyme activities and nutrient pools.Results from the N-limited forest (BIFOR FACE) indicate that elevated CO2 increased belowground carbon allocation, resulting in higher root biomass, dissolved organic carbon, microbial biomass and soil respiration. The additional carbon belowground stimulated net mineralization (+ 30%) (p
Lagrangian Coherence in Atmospheric Blocking
Authors: Schoeller Henry , Chemnitz Robin , Pfahl Stephan , Koltai Péter , Engel Maximilian
Published: March 2024

Atmospheric Blocking - also known as Quasi-Stationary Atmospheric States (QSAS) - exert a major influence on mid-latitude atmospheric circulation and are known to be associated with extreme weather events. Previous work has highlighted the importance of the origin of air parcels that define the blocking region, especially with respect to non-adiabatic processes such as moisture transport and latent heating. So far, an objective method for clustering the individual Lagrangian trajectories passing through the QSAS into larger and - more importantly - spatially coherent air streams has not been established, which is the focus of our current work.    Coherent sets are regions in the phase space of dynamical systems that keep their geometric integrity to a large extent during temporal evolution. We extract a low-dimensional representation of the Lagrangian data via diffusion maps and cluster the trajectories in this representation to estimate coherent sets. Our implementation adapts the existing methodology to the non-Euclidean geometry of Earth's atmosphere and its challenging scaling properties. Several example cases are investigated.     The results confirm the existence of spatially coherent feeder airstreams differing with respect to their dynamical properties and, more specifically, their latent heating contribution. Air streams experiencing a considerable amount of latent heating occur mainly during the maturing and maintanence phases of the QSAS and contribute to its stability. In our example cases, trajectories also exhibit an increase in density when passing through the blocking region during its maintanence phase, which is in line with the common understanding of QSAS as regions of high stability. 
How much can we get from Gade's mixing line?
Authors: Couston Louis-Alexandre
Published: March 2024

Gade’s meltwater mixing line theory is consistent with numerous under-ice ocean observations. However, it is built on an assumption that is difficult to test with field measurements, especially near the ice boundary, which is that the effective salt and temperature diffusivities are equal. In this presentation, I will discuss the validity of Gade’s mixing line theory and show how it can be used to predict melt rates, using results from direct numerical simulations of a canonical model for externally forced ice-ocean boundary layers. I will first demonstrate that the effective salt and temperature diffusivities are approximately equal across most of the boundary layer in the well mixed regime. Then, I will show how knowledge of one turbulent diffusivity (salt, temperature, or thermal driving) can be combined with knowledge of one vertical profile in the bulk (salt, temperature, or thermal driving) to predict the heat and salt fluxes at the ice-ocean boundary.
Detecting tree stress fingerprints using sub-daily sapflow data
Authors: Schackow Anna , Limousin Jean-Marc , Steele-Dunne Susan , Bastos Ana
Published: March 2024

Plants are subject to stress conditions at multiple time-scales, from minutes and hours (e.g., radiation stress) to years or decades (e.g., prolonged drought). The processes controlling how plants respond to such stressors are also time-scale dependent, from rapid physiologic and structural responses such as stomatal regulation or leaf movement, to slow responses such as pigment changes or adjustments of growth and allocation. How these different processes evolve and interact under diverse stressors influences tree health and long-term functioning and, depending on plants ability to recover, might lead to tree health decline and mortality. Observations of tree stress from space typically rely on reflectance indices, which are associated with changes or declines in leaf pigment content, leaf area, and/or fractional of vegetation cover. These changes are driven by slow or delayed reactions to environmental stress (leaf discoloration, defoliation, reduced growth, mortality and compositional changes). Microwave measurements, on the contrary, allow to more directly track vegetation water content, but they are typically available at coarse spatiotemporal scales. Signs of plant health decline or onset of mortality trajectories can, thus, take a long time to detect based on currently available remote-sensing information, limiting our ability for early detection of stress hotspots (e.g., stands at risk of drought-induced mortality).Here, we aim to explore the potential to use sub-daily microwave observations for early detection of plant stress, in the context of SLAINTE, a mission idea recently submitted in response to ESA’s 12th call for Earth Explorers. To do this, we analyze sapflow measurements covering over a decade in an evergreen broadleaf forest at the Puéchabon study site (FRA-Pue, southern France) to evaluate how sub-daily information of vegetation water fluxes might be used to identify onset and development of plant stress. We define a set of sub-daily metrics (timing of peak sapflow, sensitivity to meteorological drivers, hysteretic behaviour) and evaluate how these vary within the growing season, across years and during extreme events for multiple trees. These derived metrics could, in principle, be derived from sub-daily satellite-based observations, facilitating therefore timely assessments of plant health declines.
ECOMAN 2.0: an open-source software package for coupling geodynamic and seismological modelling.
Authors: Faccenda Manuele , VanderBeek Brandon , de Montserrat Albert , Yang Jianfeng
Published: March 2024

In this contribution we introduce ECOMAN 2.0, an open-source software package for (1) modelling the strain-/stress-induced rock fabrics and related mechanical anisotropy, and (2) performing isotropic and anisotropic inversions using real/synthetic P- and S-wave travel-times and S-wave splitting parameters.  The strain-induced intrinsic mantle fabrics are modelled inputting the velocity, pressure, temperature and dominant creep mechanism fields from large-scale mantle flow simulations into D-Rex (Kaminski et al., 2004). This open-source software has been parallelized using a hybrid MPI and OpenMP scheme and modified to account for combined diffusion-dislocation creep mechanisms, LPO of transition zone and lower mantle polycrystalline aggregates (Wadsleyite, Bridgmanite, post-Perovskite), P-T dependence of single crystal elastic tensors, advection and non-steady-state deformation of crystal aggregates in 2D/3D cartesian/spherical grids (Faccenda, 2014; Faccenda and Capitanio, 2013). The new version of D-Rex can solve for the LPO evolution of 100.000s polycrystalline aggregates of the whole mantle in a few hours, outputting the full elastic tensor of poly-crystalline aggregates as a function of each single crystal orientation, volume fraction and elastic moduli scaled by the local P-T conditions.Extrinsic elastic anisotropy due to grain- or rock-scale fabrics or fluid-filled cracks can also be estimated with the Differential Effective Medium (DEM) (Faccenda et al., 2019). Similarly, extrinsic viscous anisotropy can be modelled yielding viscous tensors to be used in large-scale mantle flow simulations (de Montserrat et al., 2021). The elastic tensors can then be interpolated in a tomographic grid for (i) visual inspection of the mantle elastic properties (such as Vp and Vs isotropic anomalies; radial, azimuthal, Vp and Vs anisotropies), (ii) generating input files for large-scale synthetic waveform modelling (e.g., SPECFEM3D format), or (iii) P- and S-wave isotropic and anisotropic inversions (e.g., Faccenda and VanderBeek, 2023). The latter can be performed with the new PSI (Platform for Seismic Imaging) module, which includes recently developed techniques for seismic anisotropic inversions of body waves (VanderBeek and Faccenda, 2021; VanderBeek et al., 2023).
Semi-Supervised Machine Learning for Predicting Lacustrine Carbonate Facies in theBarra Velha Formation, Santos Basin
Authors: Abreu Affonso Pedro Vitor , Spadano Albuquerque Ana Luiza , Durante Spigolon André Luiz
Published: March 2024

There is an increasing availability of geoscientific exploration data for the oil and gas industry. Supporting data-driven tools have become important for the optimization and geoscientific information gain from this kind of data and thus allowing a fastest and more trustable decision making. Nonetheless, the development of this kind of technology depends on the standardization of the data and its descriptive methodologies, that many times diverges between the geoscientists and its many data sources, that recurrently comes from different scales of samples. The complexity of non-conventional reservoir, like the ones from brazilian pre-salt, increases those pre-existing difficulties. In this sense, this work evaluates the results of a semi-supervised Machine-learning methodology that was applied to the aptian carbonates of Barra Velha formation, from the Santos Basin pre-salt. This methodology follows a PU-learning approach with the utilization of the Random-forest algorithm based on public data from geological cores, side samples and geophysical data from the corresponding depths of the Barra Velha carbonates. A team of geoscientists provided a carbonate facies grouping, and this work regrouped it based on quantitative and qualitative descriptions, and in depositional criteria related for those samples, aiming to better utilize this data for Machine-learning. To deal with the fact that the samples belong for different scales and data-sources, the classified samples from geological cores were select as “labeled”, and the rest of it was defined as “unlabeled”, establishing a criteria for description of the samples and that fits the workflow for semi-supervisioned Machine-learning. Model evaluation metric were analyzed and compared to results of a regular supervisioned model approach. The results show that the overall precision of the semi-supervisioned model has increased significantly by 10% in relation to the supersivioned methodology, and critical suggestions were made based on the results for motivation of future researches from this topic.
AMOC thresholds in CMIP6 models: NAHosMIP
Authors: Jackson Laura , Eduardo Alastrue de Asenjo , Katinka Bellomo , Gokhan Danabasoglu , Helmuth Haak , Aixue Hu , Johann Jungclaus , Warren Lee , Virna Meccia , Oleg Saenko , Andrew Shao , Didier Swingedouw
Published: March 2024

The Atlantic meridional overturning circulation (AMOC) is an important part of our climate system, which keeps the North Atlantic relatively warm. It is predicted to weaken under climate change. The AMOC may have a threshold beyond which recovery is difficult, hence showing quasi-irreversibility (hysteresis). Although hysteresis has been seen in simple models, it has been difficult to demonstrate in comprehensive global climate models.We present results from the North Atlantic hosing model intercomparison project, where we applied an idealised forcing of a freshwater flux over the North Atlantic in 8 CMIP6 models to explore this threshold. The AMOC weakens in all models from the freshening, but once the freshening ceases, the AMOC recovers in some models, and in others it stays in a weakened state. We will discuss mechanisms behind the different behaviour in the different models.  
Impact of deep convection on biogenic volatile organic compounds in the upper troposphere over the Amazon Rainforest
Authors: Tripathi Nidhi , Edtbauer Achim , Wang Nijing , Ringsdorf Akima , Krumm Bianca , Klüpfel Thomas , Lelieveld Jos , Williams Jonathan
Published: March 2024

Biogenic volatile organic compounds (BVOCs) play an essential role in tropospheric chemistry, forming secondary organic aerosol and influencing ambient ozone. Since particles produced from BVOCs may grow to form cloud condensation nuclei (CCN) and influence cloud properties, BVOCs also indirectly affect the global radiation budget. The terrestrial biosphere is a significant source of BVOCs, with the emissions from the tropical forests (mainly the Amazon) contributing about 80% to the global BVOC budgets. Our understanding of BVOC emissions and chemistry, particularly their role in particle formation over the Amazon rainforest, is incomplete. Therefore, a comprehensive suite of atmospheric instruments was used to measure BVOCs, particles and other trace gases over the Amazon rainforest using the High Altitude and Long-range Observation (HALO) aircraft from Dec 2022 to Jan 2023. The main focus of the field campaign was to investigate how tropical convection affects the atmospheric chemistry of BVOCs using measurements made from 300m to 15km altitude. The measurements of BVOCs were performed using PTR-ToF-MS and fast GC-MS. Isoprene was found to be the dominant BVOCs in the Amazon boundary layer. Interestingly, as a result of the regional strong convection, we observed elevated mixing ratios of isoprene (>1ppb), its oxidation products, and the sum of monoterpenes (MTs) in the upper troposphere (~10-12 km). This shows that despite the fast reaction rate of isoprene with OH (lifetime 1 hour) significant amounts can reach the outflow regions of the upper troposphere. The diel (24-hour) profile of isoprene mixing ratios, its oxidation products, and MTs in the upper troposphere were observed to change markedly with altitude. Near the surface (300m) BVOC emissions including isoprene varied with light and temperature peaking at circa 13:00 local time. However, between 10-12km, isoprene mixing ratios rose during the night and peaked before dawn and the onset of photochemical oxidation. This suggests that the nocturnal convection of residual isoprene is an effective vertical transport mechanism that primes the upper troposphere for particle production the following day. The boundary layer isoprene mixing ratios were also found to vary spatially with the strongest gradient found between the forested and deforested regions. The mean mixing ratios of isoprene (2.96 ±0.72 ppbv) and MTs (0.31±0.09 ppbv) in the forested regions were ~4 times higher than their values measured in the deforested regions. In both the boundary layer and outflow regions of the tropical Amazonian troposphere isoprene is a key player in the atmospheric chemistry. Preliminary results of the spatio-temporal variation and vertical profiles of other selected BVOCs will be presented.