bluuebunny/crossref_metadata_2025 huggingface dataset:
Prolonged multi-phase volcanism in the Arctic induced by plume-lithosphere interaction
Authors: Heyn Björn , Shephard Grace , Conrad Clint
Published: March 2024

Between about 130 and 75 Ma, the Arctic was impacted by widespread and long-lived volcanism known as the High Arctic Large Igneous Province (HALIP). HALIP is a very unusual large igneous province because it exhibits prolonged melting over more than 50 Myr with pulses of activity, an observation that is difficult to reconcile with the classic view of large igneous provinces and associated melting in plume heads. Hence, the suggested plume-related origin and classification of HALIP as a large igneous province has been questioned, and alternative mechanisms have been invoked to explain at least part of the volcanism. However, the Arctic also exhibits a very complex and time-dependent tectonic history that includes cratons, continental margins and rifting, all of which are expected to interact with the rising plume and affect its melting behaviour. Here, we use 2-D numerical models that include melting and melt migration to investigate a rising plume interacting with a lithosphere of variable thickness, i.e. an extended-basin-to-craton setting. Models reveal significant spatial and temporal variations in melt volumes and pulses of melt production, including protracted melting for at least about 30-40 Myr, but only if feedback between melt and mantle convection is accounted for. In particular, we find that melt migration transports heat upwards and enhances local lithospheric thinning, resulting in a more heterogeneous distribution of melting zones within the plume head underneath the Sverdrup Basin. Once the thicker continental and cratonic lithosphere move over the plume, plume material is deflected from underneath the Greenland craton and can then re-activate melting zones below the previously plume-influenced Sverdrup Basin, even though the plume is already ∼500 km away. Hence, melting zones may not represent the location of the deeper plume stem at a given time. Plume flux pulses associated with mantle processes, rifting of tectonic plates or magmatic processes within the crust may alter the timing and volume of secondary pulses and their surface expression, but are not required to generate pulses in magmatic activity. Hence, we propose that the prolonged period of rejuvenated magmatism of HALIP is consistent with plume impingement on a cratonic edge and subsequent plume-lithosphere interaction. Based on melt fractions, our models suggest that HALIP magmatism should exhibit plume-related trace element signatures through time, but potentially shifting from mostly tholeiitic magmas in the first pulse towards more alkalic compositions for secondary pulses, with regional variations in timing of magma types.
On the current understanding of large-scale flux ropes within solar coronal mass ejections
Authors: Möstl Christian
Published: March 2024

Understanding the large-scale structure and evolution of coronal mass ejections (CMEs) is essential for accurately forecasting their space weather impacts at Earth and other planets. There are several open issues concerning the global shape, evolution and magnetic configuration of CME flux ropes as they travel through the heliosphere, notably their deformation, erosion, deflection, rotation and coherence. Extensive progress is currently made in both regimes of observations and modeling. All types of models, being numerical, empirical or analytical, have their advantages and disadvantages. While 3D-MHD models capture the physics of CMEs in detail, very fast models can map the full parameter space and can quickly interpret multipoint CME flux rope observations. With solar cycle 25 on the rise, the spacecraft fleet Parker Solar Probe, Solar Orbiter, BepiColombo, STEREO-A, and several probes at L1 now routinely provide us with multi-spacecraft lineup observations of the same CME event. This makes it possible to combine remote sensing and in situ observations to constrain CME models. However, entirely novel types of observations are driving the field forward now. In June and September 2022, Parker Solar Probe observed CMEs in situ at 0.07 AU, setting new records for the observations of CMEs closest to the Sun. In 2023, STEREO-A acted as the first sub-L1 monitor while passing the Sun-Earth line. In March 2022, Solar Orbiter was able to measure the magnetic flux rope of a CME in situ prior to Earth impact with a long lead time, for the first time in space science history. From early 2025, Solar Orbiter will provide out-of-ecliptic measurements of CMEs, which is a much needed perspective to constrain large-scale CME flux rope models. The PUNCH mission will provide polarized heliospheric images of CMEs, which leads to the exciting possibility to determine the handedness and possibly flux rope type from remote sensing observations. Distant retrograde mission concepts like MIIST and HENON could routinely sample CMEs at spatial separations of 1-10° and 0.01 to 0.1 AU in the 2030s, when also ESA Vigil is expected to start operations.
N2O Assimilation, a New N2O Sink and Organic Nitrogen Source in Aquatic Ecosystems
Authors: Li Guangbo , Ji Qixing
Published: March 2024

Nitrous oxide (N2O) is a strong greenhouse gas with ozone layer destruction ability, and its atmospheric concentration has been increasing rapidly due to anthropogenic activities. N2O reduction to dinitrogen (N2), the last step of denitrification, was recognized as the only biological N2O sink. Recently, diazotrophic N2O assimilation to organic nitrogen in biomass by nitrogenase has been discovered in the eastern South Pacific Ocean and cultured diazotroph Crocosphaera and Trichodesmium. N2O assimilation to organic nitrogen is thermodynamically more favored than N2 fixation in higher N2O concentration and cooler environments, but the distribution and detailed mechanism of this new N2O sink are still unclear. We applied isotopic tracing experiments to validate and measure N2O assimilation and built an enzymatic kinetics model for a mechanistic explanation. Cultured diazotroph Crocosphaera (WH8501) and Trichodesmium (IMS101) both showed evident N2O assimilation rates of 0.751 nM N h-1 for Crocosphaera at [N2O]/[N2] = 0.0075, 0.690 nM N h-1 for Trichodesmium at [N2O]/[N2] = 0.01, and 0.481 nM N h-1 for Trichodesmium at [N2O]/[N2] = 0.0005. Although N2O assimilation was assumed to be carried out by nitrogenase, it was asynchronous with the diel rhythmicity of N2 fixation. Field samples from the Pearl River Estuary did not demonstrate the presence of N2O assimilation. Since N2 fixation was absent as well, the isotopic tracer 46N2O barely introduced influences on nitrogen isotopic composition compared to photosynthesis and remineralization, indicating that N2O assimilation is an insignificant N2O sink in eutrophic estuarine waters. Our enzymatic kinetic model revealed that N2 rather than N2O dominated the overall growth rates of cultured diazotrophs. The model indicated the [N2O]/[N2] required for the presence of N2O assimilation in isotopic tracing experiments and explained the absence of this process under natural N2 concentration environments. The insights from this study may suggest new engineering methods to control N2O emissions.
Analyzing non-stationarity in record-breaking temperature events over Peninsular Spain in 1960-2021 using the R package RecordTest
Authors: Castillo-Mateo Jorge , Cebrián Ana C. , Asín Jesús
Published: March 2024

The identification of non-stationary behavior in extremes is crucial for the analysis of climatic and environmental data. As an alternative to classical extreme value theory, the investigation of events that break new records proves particularly appealing. While the increment in averaged temperatures over recent decades is well-characterized and studied, the characterization of changes in record-breaking temperature events remains an open problem. In this work, the R package RecordTest (Castillo-Mateo et al. 2023a), available on CRAN (https://CRAN.R-project.org/package=RecordTest) and GitHub (https://github.com/JorgeCastilloMateo/RecordTest), is introduced. This package offers a framework for non-parametric analysis of non-stationary behavior in extremes, based on record-breaking analysis. The main idea of these inference tools is based on verifying whether the observed records in the data align with the distribution of record occurrences under stationary series of random variables. Several hypothesis tests are proposed to detect trends or change-points in record occurrences based on both upper and lower records, both in the forward and backward series. The package also implements all necessary steps in such analyses, including data preparation, record identification, exploratory tools, and supplementary graphical tools. The tools included in the package are introduced together with a careful analysis of the impact of climate change on the occurrence of calendar day records in 36 series available from the ECA&D of daily maximum temperatures in the Iberian Peninsula from 1960 to 2021 (Castillo-Mateo et al. 2023b). The objective also includes characterizing the record occurrences in different periods of the year and in different spatial regions. The effects of climate change are heterogeneous within the year, being autumn the season where the effects are weaker and summer where they are stronger. Concerning the spatial variability, the Mediterranean and the North Atlantic region are the areas where the effects are more and less clear, respectively.References:Castillo-Mateo, J., Cebrián, A. C., and Asín, J.: RecordTest: An R package to analyse non-stationarity in the extremes based on record-breaking events, Journal of Statistical Software, 106(5), 1-28, https://doi.org/10.18637/jss.v106.i05, 2023a.Castillo-Mateo, J., Cebrián, A. C., and Asín, J.: Statistical analysis of extreme and record-breaking daily maximum temperatures in peninsular Spain during 1960-2021, Atmospheric Research, 293, 106934, https://doi.org/10.1016/j.atmosres.2023.106934, 2023b.
Novel methods needed to attribute human health impacts of climate change
Authors: Mitchell Dann , Shapland Chin Yang , Lo Eunice , Tilling Kate , Leach Nick
Published: March 2024

Attribution of different hazards and impacts of climate change to specific radiative forcings, including greenhouse gasses, is emerging as a critical field for evidence-based decisions used in, e.g. legal settings, and for Loss and Damage. A recent report published by Wellcome shows that there are 13 climate-health attribution publications to date, mainly using methods that are adapted from the core attribution community, including the good practice and IPCC recommendations. Most of these studies have cut corners from what many in the attribution community would call ‘the gold standard’, but for good reason, the health signal is more complex than a purely climate signal. Here I discuss a number of new approaches that can be used to attribute human health outcomes from climate change. I give an example using forecast-based attribution, which allows for a low-bias, high-spatial resolution assessment to be made. I concentrate on the Pacific NorthWest heatwave, and couple the results to all-cause, age-specific mortality. I show how this can be used for a variety of different health outcomes, including cause-specific mortality, and morbidity, e.g. mental health related, or vector-borne diseases. I discuss how different attribution techniques can be used to complement each other in the context of health. 
 Satellite Video Remote Sensing for Flood Model Validation 
Authors: Masafu Christopher , Williams Richard
Published: March 2024

Satellite-based optical video sensors are poised as the next frontier in remote sensing. Satellite video offers the unique advantage of capturing the transient dynamics of floods with the potential to supply hitherto unavailable data for the assessment of hydraulic models. A prerequisite for the successful application of hydraulic models is their proper calibration and validation. In this investigation, we validate 2D flood model predictions using satellite video-derived flood extents and velocities. Hydraulic simulations of a flood event with a 5-year return period (discharge of 722 m3 s-1) were conducted using HEC-RAS 2D in the Darling River at Tilpa, Australia. To extract flood extents from satellite video of the studied flood event, we use a hybrid transformer-encoder convolutional neural network (CNN)-decoder deep neural network. We evaluate the influence of test-time augmentation (TTA) – the application of transformations on test satellite video image ensembles, during deep neural network inference. We employ Large Scale Particle Image Velocimetry (LSPIV) for non-contact-based river surface velocity estimation from sequential satellite video frames.When validating hydraulic model simulations using deep neural network segmented flood extents, critical success index peaked at 94% and on average improved by 9.5% when TTA was implemented. We show that TTA offers significant value in deep neural network-based image segmentation, compensating for aleatoric uncertainties. The correlations between model predictions and LSPIV velocities were reasonable and averaged 0.78. Overall, our investigation demonstrates the potential of optical space-based video sensors for validating flood models and studying flood dynamics.
A field experiment on macroplastic redistribution and fragmentation by soil tillage 
Authors: Maqbool Ahsan , Guzman Gema , Fiener Peter , Wilken Florian , Soriano María-Auxiliadora , Gomez Jose Alfonso
Published: March 2024

Soil is polluted with plastic waste from macro to submicron level, and research has intensified on the fate and transport of plastic with more focused particulate plastic, including fibers (5mm) occurrence and behavior has remained comparatively elusive, mainly due to a lack of tracing mechanism. This study utilized magnetically tagged soil movement and provided a comparison with a method for tracing macroplastic pieces labeled with a physically adhesive passive radiofrequency identification transponder used as an innovative and efficient approach. A field study following best practice approaches of soil tillage was carried out to determine the displacement of macroplastic during the non-inversion chisel and inversion disk tillage process to understand the fate of macroplastic in arable land. All the experiments were performed at plain topography to eliminate the downslope and drift effect, while tillage depth (0.15 m) and speed (4.5 km h-1) were kept constant during the tillage process. The results indicate that non-inversion tillage has a significantly more protracted macroplastic transport displacement compared to inversion tillage by a factor of 2.4.  The mean displacement of macroplastic by tillage erosion is 0.36 ± 0.25 m chisel and 0.15 ± 0.13 m disk tillage per pass. However, inversion tillage caused substantially more fragmentation of macroplastic. In general, both tillage implements drove the burial of surface macroplastic into the plow layer.  This highlights that soil can act as a long-term sink for macro and microplastic and would expect less plastic to be transported into the atmosphere and aquatic system from arable land. This project gets financing from the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement number 955334.
Projected amplification of summer marine heatwaves in a warming Northeast Pacific Ocean
Authors: Athanase Marylou , Sánchez-Benítez Antonio , Goessling Helge , Pithan Felix , Jung Thomas
Published: March 2024

Marine heatwaves are expected to become more frequent, intense, and longer-lasting in a warming world. However, it remains unclear whether feedback processes could amplify or dampen extreme ocean temperatures. Here we impose the observed atmospheric flow in coupled climate simulations to determine how the record-breaking 2019 Northeast Pacific marine heatwave would have unfolded in preindustrial times, and how it could unravel in a +4°C warmer world compared to present-day conditions. We find that air-sea interactions, involving reductions in clouds and ocean mixed-layer depth and air advection from fast-warming subpolar regions, modulate warming rates within the marine heatwave. In a +4°C warmer climate, global oceans are +1.9°C warmer than present levels, and regional mean warming in the Northeast Pacific can reach +2.3–2.7 ± 0.25°C. Our identified feedback processes are projected to further amplify the intensity and spatial extent of analogous Northeast Pacific summer marine heatwaves beyond those thresholds, with a warming reaching +2.9 ± 0.15°C above present levels. Such an event-specific amplification would place even greater stress on marine ecosystems and fisheries.
Exploring Risk Perception through a game of Downward Counterfactuals 
Authors: Gargiulo Maria Vittoria , Woo Gordon , Russo Raffaella , Napolitano Ferdinando , Amoroso Ortensia , Massa Bruno , Capuano Paolo
Published: March 2024

Italy, with its complex geological profile, faces significant seismic and volcanic hazards, particularly in the Campania region (Southern Italy). Here, the Campi Flegrei caldera, one of the most hazardous active volcanoes in the world, is located in a highly densely populated area close to the city of Naples. The caldera, thus, poses unique challenges with its submerged volcanic features, hydrothermal activity, and bradyseismic phenomena, including recent reports of inflation around Pozzuoli and increased seismic activity.Recognizing the importance of public awareness, especially among the younger generation, serious games that blend serious and playful elements emerge as innovative tools for science communication. These games actively involve participants, making learning more engaging. Parallelly, incorporating downward counterfactual analysis in risk assessment enhances disaster preparedness by considering how situations could have been worse. This approach finds application in addressing extreme natural risks like volcanic eruptions.To raise awareness, a democratic and egalitarian role-playing game was designed, providing an interactive and instructive experience. Participants engage in a roundtable of Counterfactuals in the Negative, imagining historical volcanic eruptions with worse outcomes, enhancing individual risk intelligence.An evaluation protocol has been developed to assess the impact of this experience on risk perception, with this presentation focusing on the outcomes of the 2023 edition of "Futuro Remoto," where almost 200 participants joined the game.This work has been supported by CORE ("sCience and human factor for Resilient sociEty") project, funded by the European Union’s Horizon 2020 - research and innovation program under grant agreement No 101021746.
Eoarchean-Paleoarchean crustal material in the southern North China Craton and possible mantle reservoir of early Earth
Authors: Si Bowen , Diwu Chunrong , Si Rongjun
Published: March 2024

The depleted mantle and the continental crust are largely geochemically and isotopically complementary. However, the question of when the depleted mantle reservoirs developed on Earth remains a topic of considerable debate. In this study, we report the existence of a ca. 3.8 Ga detrital zircon from the quartzite of the Paleoproterozoic Songshan Group in the southern North China Craton. In situ zircon hafnium isotopic characteristics of the 3.8–3.2 Ga detrital zircons indicate the presence of source rocks as old as ca. 4.5 Ga in the southern North China Craton. Together with the global zircon U-Pb-Hf isotope dataset from the North China Craton, Jack Hills, Acasta as well as available μ142Nd values of ancient rocks from Archean craton worldwide, the new results indicate that the silicate Earth has differentiated at 4.5–4.4 Ga almost immediately after accretion, developing continental crust and a complementary depleted mantle reservoir at that same time.
Modeling Urban Climate  in East China with CLM5 coupling Local Climate Zone Schemes
Authors: Zhang Ning
Published: March 2024

The urban expansion-induced heat can exacerbate heat stress for urban dwellers, especially during heat waves. The urban parameterization within the Community Land Model version 5 (CLM5) was modified incorporating the local climate zones (LCZs) framework, named CLM5-LCZs, to simulate the urban climate of cities in eastern China. The results exhibited that daytime and nighttime canopy urban heat island intensity (CUHII) were highest in the Compact Low Rise (LCZ3) and the Compact High Rise (LCZ1) areas respectively, while surface urban heat island intensity (SUHII) peaked in the Large Low Rise (LCZ8) and the Compact High Rise (LCZ1) areas during daytime and nighttime respectively. Urban dwellers were easier exposed to serious heat environment in LCZ3 and LCZ1 areas over the north subtropical climate zone. Contrasts of CUHII and SUHII among different urban classes could exceed 1.7 °C and 5.4°C. The intra-urban heterogeneity may alter the dominant factors controlling SUHII, which were also modulated by local climate and HW intensity. Unlike other controlling factors, the impact of local climate on the contribution from the urban-rural contrast of convection efficiency was larger than urban features. Overall, CLM5-LCZs displayed potential of implementing detailed simulations for inter- and intra-city UHIs at a larger scale, and enhancing the capabilities in modelling urban climate and exploring the causes and controls of UHIs.
SSHADE-BandList, a novel database of absorption and Raman bands of solids 
Authors: Mandon Lucia , Schmitt Bernard , Albert Damien , Furrer Manon , Bollard Philippe , Gorbacheva Maria , Bonal Lydie , Poch Olivier
Published: March 2024

A critical missing database for the astrophysics and planetary science community using spectroscopy data is a compilation of band parameters (e.g., their position, width, intensity) of solids, for comparison with laboratory and field spectra, and observations of extraterrestrial objects. While many databases exist for gases [1], there's a scarcity for solids and liquids (mostly as tables in a few books and review papers), and the mode attributions of bands is not always clear.The Solid Spectroscopy Hosting Architecture of Databases and Expertise (SSHADE) (https://www.sshade.eu/; [2]) is hosting data from 30 research groups in spectroscopy of solids across 15 countries. It provides spectra of solids relevant to astrophysics and planetary science (ices, minerals, carbonaceous matters, meteorites…) and over a wide range of wavelengths (mostly X-ray and VUV to sub-mm). Initial compilation of the “BandList” database [3], which is hosted in SSHADE, was publicly released in October 2021. It is an ongoing effort to provide the parameters (position, width, intensity, and their accuracy, shape) associated with electronic, vibration, and phonon bands of simple solids (ices, simple organics, minerals), in absorption and in Raman emission, and for different pressure and temperature. It also includes the solid composition and isotopic species involved, as well as the mode assignment (Fig. 1). The database is compilated from exhaustive review of the literature and laboratory measurements on well-characterized species, and as of early 2024, it consisted of over 1240 bands associated with 60 different band lists, including minerals and ices in different phases. An online search tool allows users to find specific bands or lists. Results can be displayed graphically using a spectra simulator with various unit and display options (Fig. 1), and data can be exported for further analysis.   Figure 1. Absorption band list of natural calcite [4] from the SSHADE-BandList interface. (a) Bands displayed individually. (b) Sum of bands of whole band list.Development of the SSHADE-BandList database interface and content will most likely last many years. This tool is expected to be crucial, aiding in the identification of unknown absorption bands in astrophysical and solar system objects, of best spectra to use in radiative transfer models, and in guiding the conception of new instruments. References [1] Albert et al. (2020), Atoms 8(4)[2] Schmitt et al. (2014), EPSC 2014[3] Schmitt et al. (2022), EPSC 2022[4] Leclef and Schmitt (2022), SSHADE/BANDLIST (OSUG Data Center)
Measuring physical damages from natural hazards in the ECB top-down, economy-wide climate stress test 
Authors: Emambakhsh Tina
Published: March 2024

In the ECB top-down, economy-wide climate stress test, we developed novel damage functions to measure damages to physical capital from different natural hazards at granular firm-level. Combining address-level, forward-looking physical risk scores from Moody’ Four Twenty Seven with projected damages from acute and chronic physical risk from NGFS, we translated firms’ exposure towards floods, wildfire and sea level rise risk to future losses on their physical capital. Using loan-level information from the euro area credit registry, we assessed the deterioration in firms' profitability and indebtness due to physical damages and subsequently the change in default probabilities and expected losses on banks' corporate loan portfolios.  The dataset is unprecedented in terms of coverage, integrating both regulatory and private data sources and comprising financial and climate risk data for a total of 2.6 million European firms and 1,600 euro area banks, covering around 80% of total loan exposures of the euro area regulatory credit registry.  Losses from physical risk were calculated as the product of firms’ future exposure towards the frequency and intensity of wildfire risk, flood risk and sea level rise and combining this with the expected physical damages as a share of GDP from the NGFS scenarios. Annual firm-level losses from physical risk were calculated between 2020 and 2050 and for three different scenarios, i.e. the NGFS Net Zero 2050, Delayed Transition and Current Policies scenarios. The results show that acute physical risk will lead to moderate to high damages on firms’ physical capital in the long term, depending on the expected temperature increase of the scenario in question. By 2050, damages will be disproportionately higher in a Current Policy scenario relative to the other scenarios, leading to a maximum deterioration of 3% of firms’ assets compared to a maximum deterioration of 1% in a Net Zero 2050 scenario. The results show that until 2050, the credit risk of borrowers most vulnerable to physical risk is around 25% higher in a Current Policy scenario relative to a Net Zero 2050 scenario.
Tracking Crystal-Melt Segregation and Accumulation in the Intermediate Magma Reservoir
Authors: Ma Jianfeng , Wang Xiaolei , Yang Alexandra Yang , Zhao Taiping
Published: March 2024

The genesis of intermediate intrusions is highly controversial, and one of the hot topics is whether they represent frozen melts or cumulates in the evolution of magmatic systems. Distinguishing accumulation from crystallization melt differentiated along the liquid line of descent is the key issue. The Paleoproterozoic intermediate intrusions in southern North China Craton provide an excellent case to decipher this issue. Multiple lines of evidence, including mineral textures, geochemistry as well as alphaMELTS modeling, indicate disequilibrium between whole-rock and minerals, with melt extraction occurring at temperatures of 760°–820°C and with 10–40 wt.% of trapped melts. Effective water storage, revealed by amphibole and clinopyroxene hygrometers, plays a crucial role in promoting crystal-melt segregation in pluton-sized reservoirs in the upper crust. This study demonstrates that the accumulation in intermediate magmas can be identified even without evident complementary initial and extracted melts and provides deep insights into the genesis of intermediate continental crust.
Holocene overbank sedimentation in Central Europe between natural and human drivers – the Weiße Elster River (Central Germany)
Authors: von Suchodoletz Hans , Khosravichenar Azra , Fütterer Pierre , Zielhofer Christoph , Schneider Birgit , Sprafke Tobias , Tinapp Christian , Fülling Alexander , Werther Lukas , Stäuble Harald , Hein Michael , Veit Ulrich , Ettel Peter , Werban Ulrike , Miera Jan
Published: March 2024

Up to several meters thick fine-grained Holocene overbank deposits are ubiquitously found in most Western and Central European lowland floodplains. However, the interplay of different possible causes for their formation are not well understood yet. Most authors suggest human-induced deforestation as the main precondition for sediment mobilisation and transport from the slopes to the floodplain, generally regarding overbank sediments as human-derived ‘legacy sediments’. In contrast, others suggest a stronger influence of climatic factors. This current research gap is caused by often missing well-resolved fluvial chronostratigraphies and spatio-temporal information about former human activity within the studied catchments. To fill this gap we exemplarily studied Holocene overbank sedimentation and possible human or natural drivers in the meso-scale Weiße Elster catchment in Central Germany by using a comprehensive geoarchaeological approach: On the one hand, we applied numerical dating as well as sedimentological and micromorphological analyses to Holocene overbank sediments along three floodplain transects. On the other hand, we built up an unprecedented systematic spatio-temporal database of former human activity within the catchment from the Neolithic until the Early Modern Ages. Together with published paleoclimatic data, this database allowed an unprecedented, systematic comparison of Holocene overbank sedimentation phases with possible human and natural external controls. Our data show that some overbank sedimentation phases were directly linked with human activities in the affected site sub-catchments, whereas others were not. Instead, all phases were clearly linked with natural factors, i.e. hydroclimatic fluctuations. This difference with most former studies could possibly be explained by previously often limited numerical dating of the fluvial sediments and by largely missing spatio-temporally well-resolved regional settlement records, hindering a precise temporal link of fluvial sedimentation with former human settlement. Furthermore, this difference could possibly also be explained by a relatively high natural sensitivity of the landscape dynamics in the Central German lowlands, showing a subcontinental climate, towards external controls. 
Assessing the influence of observations on the analysis in ensemble-based data assimilation systems
Authors: Hu Guannan , Dance Sarah , Fowler Alison , Simonin David , Waller Joanne
Published: March 2024

Convection-permitting numerical weather prediction (NWP) is crucial for forecasting high-impact weather events such as heavy precipitation, storms, floods, wind gusts and fog. The assimilation of observations plays a significant role in improving the forecasting skill of these weather events. To make better use of existing observations and guide the design of future observation networks, accurately assessing the influence of assimilated observations is essential. The degrees of freedom for signal (DFS) has long been used to assess the influence of observations on the analysis. While various methods exist for calculating the DFS in variational data assimilation (DA) systems, calculating the DFS in ensemble-based DA systems (e.g., the ensemble transform Kalman filter) is a largely unexplored area. Since ensemble-based DA systems are becoming increasingly dominant for convection-permitting NWP, practical implementation of the DFS in such DA systems is needed. Unlike in variational DA systems, the background error covariance matrix is not static in ensemble-based DA methods. Consequently, the DFS calculated at each assimilation step measures the observation influence for a certain background error covariance matrix. This means that the DFS estimates are flow dependent. In addition, domain localisation of observations is often used in ensemble-based DA systems (e.g., local ensemble transform Kalman filter). This implies that the DFS should be calculated locally. In this work, we propose novel approaches for calculating the DFS in ensemble-based DA systems and investigate existing approaches applicable to such systems. We establish their consistency under idealised conditions and discuss their differences in practical applications. To validate our theoretical findings, we conduct simple numerical experiments using JEDI (Joint Effort for Data assimilation Integration) developed by JCSDA (Joint Center for Satellite Data Assimilation).  Our results provide useful information for assessing the influence of observations in ensemble-based DA systems. This work is financially supported by the Met Office and is fully in line with the Met Office’s strategy and its ongoing development of the next generation data assimilation and observation processing system.
Enhancing Subseasonal Climate Predictions through Dynamical Downscaling: A Case Study in the Southern Plains of the United States
Authors: Chikamoto Yoshimitsu , Chang Hsin-I , Wang Simon , Castro Christopher , LaPlante Matthew , Risanto Bayu , Huang Xingying , Bunn Patrick
Published: March 2024

Predicting extreme precipitation events at subseasonal timescales is a critical challenge in Earth system science. This study advances climate predictability by employing dynamical downscaling, specifically focusing on convection-permitting modeling in the Southern Plains of the United States. Two contrasting extreme precipitation periods in Texas, the extremely dry May of 2011 and the abnormally wet May of 2015, were selected for analysis. To enhance subseasonal climate forecasting, we integrated the Weather Research and Forecasting (WRF) model with the decadal climate prediction system based on the Community Earth System Model (CESM). Evaluating the impact of dynamical downscaling on the prediction of extreme precipitation events, our study demonstrates how high-resolution downscaling enhances model skill in capturing these events. The findings hold the potential to significantly contribute to improving climate predictions and assessing regional climate-related risks, aligning with the session's goals.
Advancements in Cold Cloud Physics: Insights from a Decade of Airborne In-Situ Measurements with the PHIPS Instrument 
Authors: Järvinen Emma , Schnaiter Martin , Xu Guanglang , Wagner Shawn
Published: March 2024

Airborne in-situ measurements provide a valuable opportunity to measure ice cloud properties in their natural atmospheric contexts, significantly contributing to our understanding of complex atmospheric processes. Traditional in-situ measurement techniques, relying on forward scattering, shadowgraphs or holography, have provided valuable insights into cloud particle size information and shape. However, finding answers to unresolved research questions often requires alternative and more advanced measurement technologies.In this talk, we discuss one of those more advanced airborne instruments, a single-particle cloud imager and nephelometer (PHIPS), and review its first decade of airborne operations. PHIPS was intended to unravel the link between ice crystal microphysics and angular light scattering properties in cirrus clouds on a single particle basis. We demonstrate how the combination of angular scattering function measurements with simultaneous in-situ microscopy can be used to develop new parameterisations of ice cloud single-scattering properties for radiative transfer models. Furthermore, we explore the distinctions between these observational-based parameterisations and conventional parameterisations assuming idealised ice crystal shapes.The single-particle light scattering function, detected with high enough angular resolution, emerges as a potent tool to distinguish between spherical and aspherical particles. Consequently, such measurements could be used to reliably discriminate hydrometeor phases in mixed-phase clouds. We illustrate how this method provides new insights into the ice formation via secondary ice processes in Southern Ocean boundary layer clouds. Additionally, we present first attempts to evaluate parameterisations for secondary ice processes in numerical models (CAM6 and CM1) based PHIPS observations. Our results underscore the necessity of airborne in-situ measurements and more advanced technologies in improving our understanding of fundamental ice cloud physics. This leads to more realistic parameterisations of microphysical processes as well a radiative properties of ice and mixed-phase clouds to be used in future climate and weather predictions. 
Developing a relative quality index scheme for improving radar composite products and bias adjustment in mountainous regions, Thailand
Authors: Methaprayun Monton , Bogaard Thom Adrianus , Mapiam Punpim Puttaraksa
Published: March 2024

Radar composite products are essential for tracking and forecasting heavy storms over mountainous catchments where rain gauge information is scarce. The impact of radar beam blockage from an individual radar, resulting in low reflectivity data, can significantly contribute to the underestimation of radar rainfall estimates in such areas. The quality of rain radar composites is critical as these products will be used for near real-time forecasting of hydrometeorological hazards. This study aimed to develop a relative quality index scheme based on the radar reflectivity fraction of the compositing radars to improve the accuracy of heavy rainfall estimates in (partly) blocked areas. Three additional surrounding environmental quality indices, i.e., the distance to the radar station, the height of the beam above the ground, and the radar beam blockage fraction were integrated in the overall quality indices (QI) computation. Furthermore, we expanded the use of the QI to enhance the mean field bias adjustment in tracking high-intensity rainfall. To comprehensively assess the merits and drawbacks of the compositing methods with multiple quality indices, we compared our results with conventional and well-known maximum composite techniques. We have tested this scheme in the Khao Yai National Park, Lamtakong basin, and the surrounding areas. Two rain radar stations were selected: Sattahip, 220 kilometer southwest and Phimai, 140 kilometer North of the Lamtakong basin. Automatic rain gauges in the overlapping area were used to evaluate the radar composite product during storm events in 2020 and 2022. The results indicate that radar composite approach with multiple QIs can effectively identify areas with unreliable radar measurement. The radar reflectivity fraction was the most important quality index in the composite region, especially in the beam blockage area where the reflectivity from Phimai consistently registers lower values compared to that from the Sattahip radar. Combining this novel relative QI scheme with traditional quality indices (distance, height, and beam blockage fraction) increased the overall accuracy and reliability of heavy radar rainfall estimates. While the combined QIs and the maximum composite method resulted in composite products with similar overall accuracy, the proposed new QI method provides more coherent storm structure. Furthermore, a noteworthy finding is that heavy rainstorms in obstructed areas become visibly apparent with higher accuracy when applying thresholds to the quality index values for bias adjustment computation of the composite products. These final products of radar rainfall estimates represent a critical advancement of rain radar based Early Warning Systems for hydrometeorological hazard mitigation in mountainous regions.
Deciphering the Role of Plate Motion Changes and Inherited Structures in Mega-Transform Fault Development Using Geodynamic Numerical Models
Authors: Longley Luke , Phethean Jordan , Heron Philip
Published: March 2024

Transform faults most commonly exhibit offsets of 100 to 200 km, with a minority defined as mega-transforms with >200 km offsets. Consequently, these mega-transforms represent a relatively understudied feature of plate tectonics with our understanding of their formation and development currently incomplete. In this study, we use the numerical modelling software ASPECT (Advanced Solver for Problems in Earth's ConvecTion) to create high resolution 3D simulations of mega-transforms following oblique changes in plate motion. Specifically, we determine how inducing transpression and transtension across a mega-transform fault affects the development of new transforms and mid-ocean ridge segments. Our numerical models all implement an initial stage of orthogonal extension and continental break up along an offset rift, followed by a second stage of oblique extension across a wide range of extension azimuths (-75° to 75°). Here, we find that small transpressional changes in plate motion (-15°) lead to the development of a short 130 km long transform, whilst larger (-75°) changes in plate motion led to the development of a longer 300 km transform. Alternatively, increasingly oblique, transtensional deformation leads to increased rifting between the offset ridges with a >60° change in the extension orientation leading to continental rifting across the old transform margin. These results are analogous to real world examples such as the Davie (West Somali Basin) and Ungava Fault Zones (Davis Strait) where we also highlight the role of plate motion changes on continental cleaving. Additionally, the orientation of mid-ocean ridges and transforms in the Labrador Sea suggests a late phase of E-W extension prior to the cessation of spreading.
Comparison of marine cloud brightening in large eddy simulations
Authors: Smith William McFarlane
Published: March 2024

Modelling of marine cloud brightening (MCB), a form of solar radiation modification, has thus far proven challenging due to the incongruous nature of the scales required. The microphysics of the cloud droplets and aerosols can only be resolved at really small scales, but just as important are the large-scale impacts on circulation and radiation. Large eddy simulations (LES) seem best placed to deal with this problem; they can resolve circulation an turbulence, but also have small enough grid boxes that useful parametrisation of microphysics can be made. When coupled to parcel models their representation of microphysical processes can be improved even further, although at a computational cost. There have been multiple studies of MCB in LES so far, but with wide-ranging background conditions and experimental designs. This leads to varying results that are challenging to compare. The aim of this study is to directly compare the results of at least two LES models, MONC and DALES, for an MCB experiment. They will first be compared with a historic data set, before being configured to ran the MCB experiment. It is hoped that MONC can also be coupled to a parcel model to improve its representation of cloud microphysics.
Drivers and effects of drying terrestrial water storage on ecosystem carbon uptake
Authors: Yang Yuanhang , Yin Jiabo , Slater Louise , Liu Pan
Published: March 2024

Terrestrial water storage (TWS) is a crucial component in regulating global water and energy budgets, exerting significant impacts on the ecosystem carbon cycle. However, the physical mechanisms behind changes in TWS and its causal relationship with terrestrial carbon uptake remain elusive. Here, we explore water-heat-carbon dynamics using a convergent cross mapping method based on eddy-covariance flux measurements. Then, we employ a supervised machine learning model and path analysis to evaluate the effects of drying TWS on vegetation photosynthesis and respiration. Finally, we project future TWS and drought conditions as well as their impacts on ecosystem vegetation productivity at the global scale. We find that temperature, soil moisture, and radiation are dominant factors regulating carbon update. In most regions of the globe, soil moisture influences vegetation photosynthesis, while the Leaf area index (LAI) plays a dominant role in humid and hyper-dry regions. Our cascade model chain projects that future drought events may have severe negative impacts on vegetation productivity. Terrestrial productivity is projected to be constrained over a growing proportion of global land surface, from the historical period (65.36%) to SSP126 (68.5%), SSP370 (67.4%) and SSP585 (70.67%). As drought severity escalates from moderate to severe, gross primary productivity (GPP) anomalies decrease from -3.53 to -8.4 , suggesting that higher water stress lowers the terrestrial carbon sink. Our results highlight the urgency of enhancing ecosystem resilience to increasingly severe drought conditions.
Predicting global change effects on reservoir sedimentation
Authors: Haun Stefan , Mouris Kilian , Schwindt Sebastian , Wieprecht Silke
Published: March 2024

Water availability is not uniformly distributed, and water is not available on demand in many areas of the world. Thus, artificial storage of water is essential for the sustainable management of water resources. However, reservoirs are transport-limited systems due to low flow velocities, resulting in sedimentation. Additionally, global change amplifies sedimentation because of altered hydrological conditions and sediment production of river basins. Preparedness for global change necessitates decades-long forecasting of these complex phenomena, which is computationally challenging. Sediment depositions reduce not only the available storage volume over time but may create severe safety issues, such as blockage of bottom outlets or increased flood risk. Therefore, it is essential to understand not only the trapping efficiency of a reservoir and its temporal variations but also the spatial distribution of expected sediment accumulations. To generate these insights, long-term predictions based on three-dimensional (3d) hydro-morphological models considering the changing climate are required.The Banja reservoir, located in southeast Albania, was investigated in this study to investigate the effects of global change on reservoir sedimentation. Simulations were performed up to 90 years into the future to model characteristic sedimentation stages and to test for differences between several emission scenarios, combined with socioeconomic and climate scenarios. A 3d numerical model simulated hydrodynamics, suspended sediment transport, and sedimentation processes, considering the Devoll River as the main tributary and three smaller tributaries. To enable long-term simulations, an adaptive grid with a spatial resolution of 50 m x 50 m in the x- and y-direction, respectively, as well as up to 10 cells in the z-direction was used. Due to an implicit time discretization a time step of 5,400 seconds was chosen to achieve reasonable computational times.The model results showed a decrease in the trapping efficiency by 2100 for all scenarios, which is associated with storage loss over time. In the high and medium emission scenarios, the reservoir experiences a substantial loss of storage volume due to increasing sediment yields. The model also showed the formation of a delta at the head of the reservoir and the progressive movement of the delta further into the reservoir. These spatial and temporal insights into future sediment deposition patterns are crucial for developing sustainable management strategies to account for global change.