bluuebunny/crossref_metadata_2025 huggingface dataset:
Latent Dirichlet Allocation: a new machine learning tool to evaluate CMIP6 climate models atmospheric circulation and extremes
Authors: Malhomme Nemo , Podvin Bérengère , Faranda Davide , Mathelin Lionel
Published: February 2023

Climate models aim at representing as closely as possible the statistical properties of the climate components, including the extreme events. This is a fundamental requirement to correctly project changes in their dynamics due to anthropogenic forcing. In order to evaluate how closely models match observations, we need algorithms capable of selecting, processing and evaluating relevant dynamical features of the climate components. This has to be reiterated efficiently for large datasets such as those issued from the Coupled Model Intercomparison Project 6 (CMIP6). In this work, we use Latent Dirichlet Allocation (LDA), a statistical learning method initially designed for natural language processing, to extract synoptic patterns from sea-level pressure data and evaluate how close the dynamics of CMIP6 climate models are to the state-of-the-art reanalyses datasets such as ERA5 or NCEPv2, in general as well as in the case of extremes.LDA allows for learning a basis of decomposition of maps into objects called "motifs". Applying it to sea-level pressure data, reanalysis or simulation, robustly yields motifs that are known relevant synoptic objects, i.e. cyclones or anticyclones. Furthermore, LDA provides their weight in each of the maps of the dataset, their most probable geographical position and their possible changes due to internal variability or external forcings. LDA decomposition is efficient and sparse, most of the information of a given sea-level pressure map is contained in few motifs, making it possible to decompose any map in a limited number of easy-to-interpret synoptic objects. This allows for a variety of new angles for statistical analysis.We look at the dominant motifs and their distributions either on entire datasets or conditionally to particular extreme events, such as cold or heat waves, and compare results between reanalysis data and historical simulations. This enables us to assess which models can or cannot reproduce statistical properties of the observations, and whether or not there are properties that no model yet demonstrates. We find that models can capture the statistical synoptic composition of sea-level pressure data in general, but that some drawbacks still exist in the modelling of extreme events. LDA can also be applied separately to each dataset, and the two resulting synoptic bases can be compared. We find the sets of motifs from reanalysis and historical simulations are very similar, even if different spatial resolutions are used.
CFD Modelling of Local Scour and Flow Field around Isolated and In-Line Bridge Piers using FLOW-3D
Authors: Harshvardhan Harshvardhan , Kaushal Deo Raj
Published: February 2023

Scouring at bridge piers is troublesome and inevitable at the same time. Numerous empirical studies have been conducted in the last century to predict scour depth, but they completely ignore the physics of the problem. The physics behind scouring at bridge piers can be best understood in terms of the effect of the flow field around the pier at different stages of scour. This study comprises experimental and numerical parts. Experiments are conducted in the laboratory in which the flow field data at equilibrium is collected using Acoustic Doppler Velocimeter (ADV) and the equilibrium scoured bed is measured around isolated and In-Line Piers. Additionally, the commercial CFD code “FLOW-3D HYDRO 2022 R1” is utilized to simulate the flow field and scour around bridge piers. The FLOW-3D model solves the three–dimensional momentum and continuity equations coupled with the sediment transport equations to calculate and predict the flow field and the equilibrium scoured bed. While the maximum scour depth at equilibrium has been used to validate various CFD codes in the past, point-wise comparison of scour depth is scanty in previous research works. Moreover, the flow field at the equilibrium scour stage obtained using FLOW-3D has also been compared with experimental data available in the literature and experiment conducted in the laboratory. The performance of the CFD model is evaluated, the flow field and scoured bed geometry at equilibrium are analyzed and results are presented.
Analyzing the rheological behavior of medium fine iron ore slurry.
Authors: Mishra Stuti , Kaushal Deo Raj
Published: February 2023

A slurry pipeline is a specially designed pipeline used to transport the tailings, wastes from the mining, ores like iron or coal to long distances. A commercially tested solution for the transport of iron ore slurry over the farthest distances in a pipeline includes various parametric checks. For the slurry to move without any hassle in the pipe maintaining the required velocity, it is important to keep some parameters in the desired limits, the most important of which is the rheological characteristics of the slurry. The rheological characteristics gives us an idea about the viscous properties, stress strain behavior of the iron ore exhibiting in its surrounding. The rheological parameters of the iron ore slurry were measured using a high precision Anton paar RheoloabQC Rheometer. At different concentrations the samples were tested keeping the particle size to be same for all the observations. While the method has been kept the same for the experiments, different rotating tools are used in the rheometer to check the accuracy of the data as well as to draw a comparison on the data obtained from them for each level of concentration. Our study majorly deals with a comparative assessment of the performance of the various rotating tools to study the rheology of the iron ore slurry.
Influence of large-scale climate modes and local hydrometeorological factors in predicting basin scale rainfall and streamflow: A Bayesian network approach
Authors: Das Prabal , Chanda Kironmala
Published: February 2023

This article reports the findings of a recent study by Das and Chanda (2022), wherein a Bayesian Network (BN) approach was applied to analyze the influence of large-scale climate modes and local hydro-meteorological variables on streamflow and rainfall in four river basins in India. Bayesian Networks (BN) offers a thorough conditional independence structure that can improve comprehension and forecasting of hydroclimatic systems. This served as the main impetus for the work, which explored the relative contributions of large-scale climate modes and local hydro-meteorological variables for the prediction of rainfall and streamflow at the basin scale. Once the conditional independence structure is developed, variables possessing a ‘directed arc’ from the target variable were selected as the potential predictors for developing the prediction models. The results showed that the most important predictors for streamflow were rainfall, u-wind, and soil moisture, while the most important predictors for rainfall were u-wind, air temperature, geo-potential height, precipitable water, vertical velocity, and relative humidity. The analysis also revealed that the influence of large-scale climate modes on the target variables was generally insignificant, except for the Pacific Decadal Oscillation and El-Niño Southern Oscillation. Furthermore, the network structure showed that about 87 and 97% of the initial inputs are redundant. The accuracy of the prediction models are comparable across all of the basins and is higher for rainfall (Refined index of agreement (MD) ranging from 0.61 to 0.81) than for streamflow (MD ranging from 0.61 to 0.78). The study also found that dry, intermediate, and wet months can be satisfactorily classified using two drought indices, the Standardized Drought Index (SDI) for streamflow and the Standardized Precipitation Anomaly Index (SPAI) for rainfall.Keywords: Large-scale climate modes, local hydro-meteorological variables, Bayesian Networks (BN), Standardized Drought Index (SDI), Standardized Precipitation Anomaly Index (SPAI)Reference:Das P, Chanda K (2022) A Bayesian network approach for understanding the role of large-scale and local hydro-meteorological variables as drivers of basin-scale rainfall and streamflow. Stoch Environ Res Risk Assess 2:. https://doi.org/10.1007/s00477-022-02356-2
Comparison of Regional Climate Model Simulations to Observational Data for Georgia
Authors: Elizbarashvili Mariam , Mikuchadze George , Kalmár Tímea , Pal Jeremy
Published: February 2023

The global climate change resulting from natural and growing anthropogenic factors of particular importance for the territory of Georgia as the frequency and intensity of extreme weather events (extreme high temperatures, heavy precipitation levels, and agricultural and ecological droughts) are increasing in the territory. Georgia’s complex orography and proximity to the Black and Caspian Seas necessitates the use of high-resolution models, such as regional climate models, to assess future climate change hazards. In this study, we analyse the output from high-resolution simulation of mean and extreme precipitation and temperature using the Abdus Salam International Centre for Theoretical Physics Regional Climate Model version 4.7.1 for the period of 2010–1014 as an initial assessment of model performance for the territory. The simulation is performed at a 12 km horizontal grid spacing using ERA5 data as boundary conditions. Comparison with observed station data shows that the model performs better in simulating the monthly mean and extreme values of temperature than precipitation. In some mountain stations, the biases between observation and simulated precipitation are high, partly due to the mountainous terrain, when the horizontal resolution of the model (12 km) can lead to a significant discrepancy between the model's points and the locations of weather stations.  This study represents the first step of Georgia’s first high resolution assessment to better understand how climate change will impact the territory required to climate change policy and decision-making.This work was supported by Shota Rustaveli National Science Foundation of Georgia (SRNSFG) № FR-19-8110.
Distribution and bioavailability of rare earth elements (REE) in metal-rich marshland soils using passive samplers
Authors: Ruiz Cánovas Carlos , Basallote Maria Dolores , Mendez Aaron , Leon Rafael , Romero Jonatan , Millan-Becerro Ricardo , Pérez-López Rafael
Published: February 2023

Rare earth elements (REE) are a group of chemically similar metallic elements (i.e. lanthanide which are becoming increasingly important in the transition to a green, low carbon economy due to their key role in permanent magnets, lamp phosphors, batteries, catalysts and other applications [1]. The growing use of REE has led to an inherent increase of REE emissions into the environment and may pose a risk to living organisms, therefore their distribution and bioavailability should be studied across different environments. The distribution and bioavailability of REE in metal-rich marshland soils was studied by performing a transect sampling across the marshland and the combination of 24h passive sampler deployment (diffusive gradient in thin films; DGTs) and determination of labile fractions (i.e., porewaters, ion-exchangeable, acid-extractable and associated to carbonate). REE in DGTs ranged from 0.75 to 4.9 μg/L, while in porewaters most samples exhibited values below the detection limit of the equipment, which highlights the suitability of these devices to monitor trace pollutants at low concentrations in estuarine sediments. A spatial trend in REE and Y absorption by DGT was observed, with increasing values in sediment depth and with river influence. REE and Y are scarcely contained in the ion-exchangeable fraction, and preferentially associated to the carbonate-associated and acid-extractable fractions, although exhibiting a high variability. This variability seems to be controlled by the mineralogical assemblage, especially those REE carrying minerals (e.g., Al oxyhydroxysulfates, phosphates, poorly-sorbed onto Fe oxyhydroxysulfates and aluminosilicates). A comparison between REE and Y concentration in labile fractions (porewaters, DGTs, sequential extractions) showed no relationship between concentrations in DGTs and the rest of labile fractions. The application of NASC-normalized patterns to environmental compartment studied suggest that the REE and Y retained in the sediment does not only come from labile species in porewaters but also from the passing of Al nanoparticles and colloids contained in the sediments through the membranes of the DGTs.AcknowledgementsThis work was supported by the Spanish Ministry of Economy and Competitiveness under the research project TRAMPA (MINECO; PID2020-119196RB-C21).[1] Binnemans, K., Jones, P.T., Blanpain, B., Van Gerven, T., Pontikes, Y., 2015. Towards zero-waste valorisation of rare-earth-containing industrial process residues: a critical review. J. Clean. Prod. 99:17–38. https://doi.org/10.1016/j.jclepro.2015.02.089.
Downwelling dense mantle residues and hotspot magmatism
Authors: Phethean Jordan J.J. , Papadopoulou Martha , Peace Alex L. , van Hunen Jeroen
Published: February 2023

The geodynamic origin of melting anomalies found at the surface, often referred to as hotspots, is classically attributed to mantle plume processes. The coincidence of hotspots and regions of relatively thin lithosphere, however, questions the necessity for mantle plumes in driving hotspot magmatism, especially as the ability of mantle plumes to thin strong mantle lithosphere is disputed. Here, we propose a new mechanism for the self-sustained generation of magmatism at hotspots where the lithosphere-asthenosphere boundary occurs at < ~100 km. By considering the effects of both chemical and thermal density changes during partial melting of the mantle (using appropriate latent heat and depth-dependent thermal expansivity parameters), we find that mantle residues experience an overall instantaneous increase in density when melting occurs at < ~3 GPa. This controversial finding is due to thermal contraction of material during melting, which outweighs chemical buoyancy effects when melting at shallow pressures (where thermal expansivity is high, at ~4.91 x 10-5 K-1). These dense mantle residues have a tendency to sink beneath melting regions, driving the return flow of fertile mantle into the melting region and locally increasing magmatic production. This mechanism presents an alternative to the upwelling of hot mantle plumes for the generation of excess melt at hotspots and the genesis of large igneous provinces during continental breakup. We model the development of magma-rich margins using geodynamic numerical models and find a close match between modelled volcanic crustal thicknesses and real-world observations. “Hot”-spots and large igneous provinces, therefore, may not require the elevated temperatures commonly invoked to account for excess melting.
Modelling soil moisture dynamics of an irrigated agroforestry windbreak system in South Africa
Authors: Hoffmeister Svenja , Zehe Erwin
Published: February 2023

The understanding of soil hydrological processes in agroforestry systems has increased in recent years. However, key aspects determining the successful functionality of agroecosystems (e.g. plant-water availability, nutrient supply) are influenced by many factors and are therefore challenging to generalize. Such information is critical for management and planning strategies. If dominant processes such as evapotranspiration and the related controls on the soil water stock can be represented adequately in hydrological models at the plot scale, they can provide useful insights for practitioners.Here, we tested whether the physically-based CATFLOW model is capable of reproducing soil moisture dynamics in a South African agroforestry system consisting of windbreaks and irrigated blackberry plants. We initialised the model with matric potential measurements and calibrated it to soil moisture dynamics at two locations with differing vegetation within the test site. After successful calibration, several numerical experiments were performed to shed light on the presence and absence of windbreaks and of different irrigation strategies on the seasonal dynamics of plant available soil water at the test site. The model and observations were also compared in the frequency domain by using empirical mode decomposition as an additional model verification.The measured soil moisture time series are dominated by a gradual drying of the soil throughout the summer, which is less pronounced in the deeper soil ranges, while several rain events interrupted this general pattern. The model captured the drying as well as the amplitudes of the rain peaks well. However, there was an offset between measured and modelled absolute values due to the initiation based on matric potential. The simulated water balance revealed distinct differences between the windbreak and berry rows due to differences in rain interception, and evapotranspiration or irrigation patterns. Similarities in the frequency spectrum of observed and modelled values were apparent. On the other hand, the modelled time series showed more distinct spectra and less noise. Currently, more detailed analyses are being carried out to extract information from the frequency spectra.
Adaptive operation of reservoirs in the Lower reaches of Jinsha River at the dry season under climate change
Authors: Jia Wenhao , Fu Guobin , Chen Mufeng , Wang Sen
Published: February 2023

             Reservoir operation is important to realize the coordination of social, economic and environmental systems. However, climate events have changed the water cycle process and the spatial-temporal distribution of the water resource system, which has brought new challenges to regional water resources management and reservoir operation. This study aims at analyzing the impacts of climate change on the multi-objective reservoir operation at the dry season, and the adaptive reservoir operation scheme for future climate change scenarios. The Jinsha River, at the upper reaches of the Yangtze River, was chosen as the research area because a large number of reservoirs have been built in the basin. Firstly, the Pettitt, MK and Moving t-test methods were used to identify the abrupt points of the hydro-meteorological data series from 1957 to 2018, and then the SWAT model was used to quantify the impacts of climate change on the runoff in the Jinsha River. Secondary, the multi-objective optimal operation model of cascade reservoirs was constructed, and then an improved PA-DDS method is developed to find the Pareto front between ecological protection and power generation. Thirdly, the impacts of climate change on reservoir operation were analyzed by comparing the scheduling results between the pre-change period (1957-1996) and the post-change period (1997-2018). Finally, using the Delta downscaling method, the GCM models chosen by suitability assessment were inputted into the SWAT model to simulate the future runoff for the reservoir operation model under different scenarios. The results showed that (1) the temperature and precipitation in the Jinsha River faced an abrupt change in 1997, while the runoff changed in 1997 and 2004. (2) the SWAT model can well simulate the daily runoff of Jinsha River (Re<15%, NSE>0.79, R2>0.8), while climate change accounts for 52.4% and 52.1% of runoff change during 1997-2004 and 2005-2018, respectively. (3) climate change can increase the ecological deviation degree and the power generation of reservoirs. In addition, compared with the traditional optimal scheduling scheme, the potential climate change brings higher requirements for water resources optimization in the future. (4) From 2021 to 2100, the temperature, precipitation and runoff of the Jinsha River are continually increased compared with the pre-changed period. It should be noted that the runoff from September and October is significantly reduced in most scenarios, increasing the insufficient storage risk of cascade reservoirs; man-made floods may be caused by the increasing runoff from April to June and the concentrated discharge of reservoirs before flood season. This study can provide theoretical support for reservoir operation and provide technical references for the impact mechanism of climate change on water resources and their management.
Seismic and geologic data from southern Gulf of Mexico imply a weakening of the Loop Current since the Mid Pleistocene Transition
Authors: Huebscher Christian , Nuernberg Dirk
Published: February 2023

At the beginning of the Mid-Pleistocene Transition (MPT) ~920 ka BP the northern hemisphere ice shields expanded, causing a significant climate change in NW Europe. Previous studies explained the northern hemisphere cooling by cooling of sea-surface temperatures, increased sea-ice cover and/or changes in the Atlantic Meridional Overturning Circulation (AMOC) strength.In their recent study Hübscher and Nürnberg (2023) discuss very-high resolution parametric echosounder imagery and sediment core analytics from a plastered drift at the eastern Campeche Bank (southern Gulf of Mexico), which was deposited under the influence of the Loop Current (LC). The LC transports warm tropical waters from the Caribbean into the Gulf via the Yucatan Channel. After its outflow into the Atlantic this warm water is a key component of the Gulf Stream system, driving the ocean heat, salinity, and moisture transport towards the N Atlantic. The joint interpretation of reflection patterns, age constraints from color-scanning, foraminiferal stable oxygen isotopes, Sr isotope ratios and core-seismic integration provides a clear line of evidence that LC strength changed across the MPT, thereby modulating the deep base level and the deposition of the plastered drift. The development of offlapping or onlapping plastered drifts is explained by changes in the depth of the relative deep base level due to changes in the flow regime.The Middle Miocene to Pliocene closure of the Central American Seaway caused the onset and intensification of the LC, a deep base level fall and deposition of offlapping prograding clinoforms similar to forced regression systems tract as usually recognized  from shelf areas. The deep base level fall caused sediment truncation above 500 m present day water depth. Below 500-550 m, the offlapping succession is overlain by sigmoidal and onlapping, transgressive systems tract like clinoforms. The transition from deep base level fall prior to the MPT to deep base level rise documents the weakening of the LC during the early MPT. After the MPT, the LC continued to weaken. The related reduction of heat transport from the Western Atlantic Warm Water Pool into the North Atlantic contributes to the further cooling of the northern hemisphere. Generally, the development of offlapping or onlapping plastered drifts or the transition between the two termination patterns can be explained by changes in the depth of the relative deep base level and interpreted by changes in the flow regime. Hübscher, C., Nürnberg, D., 2023. Loop Current attenuation after the Mid-Pleistocene Transition contributes to Northern hemisphere cooling. Marine Geology 456, https://doi.org/10.1016/j.margeo.2022.10697
The deterministic excitation paradigm, with application to the glacial-interglacial transitions
Authors: Pierini Stefano
Published: February 2023

A deterministic excitation (DE) paradigm is formulated, according to which the abrupt glacial-interglacial transitions occurred after the Mid-Pleistocene Transition correspond to the excitation by the orbital forcing, of nonlinear relaxation oscillations (ROs) internal to the climate system in the absence of any stochastic parameterization. Specific rules are derived from the DE paradigm: they parameterize internal climate feedbacks which, when activated by the crossing of certain tipping points, excite a RO. Such rules are then applied to the fluctuations of the glacial state simulated by a conceptual model subjected to realistic orbital forcing. The timing of the glacial terminations thus obtained in a reference simulation is found to be in good agreement with proxy records; besides, a sensitivity analysis insures the robustness of the timing. The role of noise in the glacial-interglacial transitions and the problems arising in the implementation of theories in which noise is crucial (such as stochastic resonance) are finally discussed. In conclusion, the DE paradigm provides the simplest possible dynamical systems characterization of the link between orbital forcing and glacial terminations implied by the Milankovitch hypothesis.
Adapting to reductions in water availability under climate change in the Murray-Darling Basin, Australia
Authors: Post David
Published: February 2023

The Murray-Darling Basin in south-eastern Australia is one of the world’s largest rivers, draining an area of just over 1 million square kilometres. The basin drains about one-seventh of the Australian land mass and is the 16th longest river in the world. However, being located on the driest continent on Earth, its discharge is relatively small, averaging just 767 m3/s, far smaller than the discharge from any other similarly sized river worldwide.Despite the relative lack of water, the Murray-Darling Basin is one of the most significant agricultural areas in Australia. In order to manage the water in the basin, in 2008 the Murray-Darling Basin Authority was formed with a mandate to manage the Murray-Darling Basin in an integrated and sustainable manner. Water reform in the basin has been a world-first in terms of the scale of intervention, but it has led to numerous conflicts in terms of access to water. The ability to manage the basin adequately relies on appropriate research being carried out in order todetermine how much water is currently available, where it is currently being used, and how water availability and use are likely to change into the future.Like much of southern Australia, the Murray-Darling Basin is already feeling the impacts of climate change, with more hotter days, fewer cold days, and a reduction in cool-season precipitation. These changes are only likely to increase over the coming decades and adaptation options to cope with less water availability are needed.Additionally, the Murray-Darling Basin Plan which was brought into force in 2012 is due for evaluation in 2025 and review in 2026. CSIRO is carrying out research across multiple disciplines in order to assist in this evaluation and review. This presentation will summarise the management of the basin to date, review likely climate change impacts and assess potential adaptation options moving forward.
Late Quaternary paleovalley systems detections through mHVSR technique: two case studies from the Adriatic coastal plain of Italy
Authors: Di Martino Andrea , Sgattoni Giulia , Di Paola Gianluigi , Berti Matteo , Amorosi Alessandro
Published: February 2023

Late Quaternary paleovalley systems are sedimentary bodies, tens of m thick and a few km wide, that are typically buried beneath modern deltas and coastal plains and that have no obvious geomorphological expression. Paleovalley systems are increasingly studied worldwide as they are considered possible amplifiers of earthquake damage due to the sharp contrast between their soft and unconsolidated sediment fill and the adjacent substrate. In this study, using previous high-resolution stratigraphic reconstructions of the Pescara and Manfredonia paleovalleys in the Adriatic coastal plain (Italy), we investigate the potential of the microtremor-based horizontal-to-vertical spectral ratio technique (mHVSR) to identify these sediment bodies in the subsurface. We acquired 23 microtremor measurements in the Pescara area and 54 at Manfredonia along two transects transversal to the paleovalley axes. At both sites, we were able to detect resonance peaks that we correlated with stratigraphic data. In the Pescara paleovalley system, we identified low-amplitude resonance peaks at frequencies varying between 0.9 and 4 Hz, clearly denoting a U-shaped feature with lower frequencies in the central part. At Manfredonia, the resonance peaks are more prominent (with mHVSR amplitude up to 7), and the paleovalley system is denoted by resonance frequencies between 0.9 and 2.5 Hz, with a more complex geometry shaped by the interactions of the Candelaro, Cervaro, and Carapelle rivers. Using the well-known facies architecture as a guide, we constrained the mHVSR resonance peaks to create a Frequency-Depth model and transformed the mHVSR curves from the frequency to the spatial domain to reconstruct paleovalley geometries and infer Vs models. We thus obtained the 2D models of the paleovalleys profiles. The Pescara mHVSR model shows a sedimentary cover thickness varying from 10 m (on the interfluves) to 40 m (in the depocentre). At Manfredonia, the sedimentary cover has similar thickness, in the range of 10-45 m, with variations that reflect its complex internal geometry. At both sites, paleovalley fills are characterized by low Vs velocities: comparable Vs values were obtained from the two depocentres (about 180 m/s at Pescara and 140 m/s at Manfredonia), which places paleovalley fills into the ground type D of the Standard Eurocode 8. The fundamental resonance frequencies show considerable variability along the investigated transects on very short distances (few hundred meters), in a range of frequencies that can interact with the most common building types. We mapped this variability and observed excellent correlation with the geologic cross-sections, proving the mHVSR to be an effective tool for mapping these particular sediment bodies. The 2D models obtained will serve as a basis for future seismic response simulations.
Explainable AI for oceanic carbon cycle analysis of CMIP
Authors: Heubel Paul , Keppler Lydia , Iliyna Tatiana
Published: February 2023

The Southern Ocean acts as one of Earth's major carbon sinks, taking up anthropogenic carbon from the atmosphere. Earth System Models (ESMs) are used to project its future evolution. However, the ESMs in the Coupled Model Intercomparison Project version 6 (CMIP6) disagree on the biogeochemical representation of the Southern Ocean carbon cycle, both with respect to the phasing and the magnitude of the seasonal cycle of dissolved inorganic carbon (DIC), and they compare poorly with observations.We develop a framework to investigate model biases in 10 CMIP6 ESMs historical runs incorporating explainable artificial intelligence (xAI) methodologies. Using both a linear Random Forest feature relevance approach to a nonlinear self organizing map - feed forward neural network (SOM-FFN) framework, we relate 5 drivers of the seasonal cycle of DIC in the Southern Ocean in the different CMIP6 models. We investigate temperature, salinity, silicate, nitrate and dissolved oxygen as potential drivers. This analysis allows us to determine dominant statistical drivers of the seasonal cycle of DIC in the different models, and how they compare to the observations. Our findings inform future model development to better constrain the seasonal cycle of DIC.
Urban canopy parameterization of the non-local building effects with variable building height
Authors: Lu Jiachen , Nazarian Negin , Hart Melissa , Krayenhoff Scott , Martilli Alberto
Published: February 2023

Variability of building height induces flow heterogeneity and directly controls the depth of the roughness sub-layer, the strength of mutual sheltering, and the overlapping of urban canopy flow, which poses challenges for accurate modeling. Large-eddy simulations over 96 building arrays with varying density, height variability (standard deviation of building height), and horizontal arrangements were conducted to reveal the impact on the urban flow. Results demonstrate a strong non-local building effect on the flow due to height variability, where flow around high buildings possesses high wind speed, dispersive momentum flux, and other distinctive flow patterns, whereas around low buildings, the flow pattern is less unique. The complex flow behavior is beyond the capacity of the current multi-layer urban canopy model (MLUCM) where turbulent constants and drag effects were considered in a simplified way. The increased height variability and urban density also blur the interface of urban canopy, further making MLUCM estimates model constants heavily based on a clear urban canopy inappropriate. Based on the original model, we comprehensively tested potential contributing factors such as the estimation of displacement height, height-dependent drag coefficients, and the extended roughness sublayer. The modified model provides a better overall agreement with the LES results, especially above the mean building height where the prediction of the extended urban canopy layer is largely improved. 
Mineral dust in Namibia: new research on emissions, transport and properties
Authors: Formenti Paola
Published: February 2023

While the most extensive and active sources of mineral dust are found at mid-latitudes (Sahara, East Asia and the Arabic peninsula), source areas at high latitudes both in northern and the southern Hemispheres, are gaining attention because of their distinct characteristics and impacts at the appropriate regional and semi-hemispheric scales.Southern Africa is estimated to account for approximately 5% of the global annual emissions of mineral dust and the long-range transport of dust emitted from these regions are shown to head towards the South Atlantic, the southern Oceans, and across the subcontinent by both observations and modelling.In particular, hundreds distinct point sources have been identified in Namibia, including the topographical lows of the Etosha pan alluvial basin, the dry lands (Kalahari Desert, gravel plains bordering the Namib Deserts), but mostly the numerous ephemeral riverbeds, pans, wetlands and possibly mines along the coastline. By deposition, this windblown dust could impact to the productivity of the waters offshore, but also the formation and the chemical composition of the fog and low marine clouds. Through the fog, the dust emitted has the potential of redistributing nutrients not only to the marine but also to the continental ecosystems. Likewise, the strong and almost omnipresent southerly trade winds driven by the temperature contrast between the cold Benguela current and warm and dry continental desert air masses also provide an opportunity to transport sediment influenced by the nutrient rich aerosols of the ocean further onto land to nourish the nearshore ecosystems. To date, the majority of dust emissions observations from this region have relied heavily on the improved ability of satellite platforms to optically isolate dust aerosols over the ocean surface and despite the consistent high winds from the south, have excluded the potential for dust emission transport processes towards the interior.This presentation illustrates the new results of recent coordinated research exploring the emissions, the transport, and properties of net transported mineral dust from Namibia sources. These new results rely on model simulations at different spatial resolution, on the analysis of local and regional wind regimes, on field observations, and on laboratory-based experiments on airborne dust generated from natural soils. Our results demonstrate that the frequency of emission might be higher than expected by only easterly berg winds. We also suggest that the Namibian dust may be transported to Antartica and that its processing by marine biogenic emissions could be responsible for the seasonal increase in the dust iron solubility observed in the Austral fall.
Ground Deformation Monitoring in Beijing-Tianjin-Hebei Metropolitan Region Using Time Series InSAR Method
Authors: Ran Yongxuan , Hu Xie , Tang Qiuhong
Published: February 2023

To accommodate the acceleration and expansion of urbanization, it is necessary to monitor urban geological disasters such as land subsidence. The Beijing-Tianjin-Hebei metropolitan region, as a national strategic supersite in China to promote the innovation of regional development systems and mechanisms, has constantly struck by major disasters. Using satellite images provided by the European Space Agency's Copernicus Sentinel-1 mission, this study applies time-series Interferometric Synthetic Aperture Radar (InSAR) analysis to measure and cross-validate the ground deformation in the Beijing-Tianjin-Hebei region based on ascending and descending orbital results. In Beijing, the eastern part is subject to faster sinking rate than other areas. There are three evident areas with high subsidence rates, and the maximum cumulative sinking rate reaches -60 mm/yr during 2017-2022. The exploitation of groundwater and underground space are the primary drivers for ground deformation in Beijing-Tianjin-Hebei. The land subsidence has been recently mitigated by the replenishment of groundwater from the South-to-North Water Diversion Project. Our study shows that time-series InSAR analysis is an effective tool to assess the hazard exposure in metropolitan areas for an ultimate goal of urban resilience.
Testing the robustness of precipitation cluster scalings with an ensemble of aquaplanet simulations
Authors: Stephan Claudia
Published: February 2023

Large and/or long-lived convective clusters are associated with extreme weather, drive the global circulation by forcing atmospheric waves, and affect the energy budget of the atmosphere by modulating outgoing longwave radiation in their vicinity. The majority of tropical clusters follow scale-free occurrence frequency distributions for cluster sizes and the rainfall integrated over a cluster (intensity). The relationships between intensity and area, and circumference and area also follow scaling laws. The exponents of all of these four scaling laws follow when we assume that precipitation clusters inherit their properties from the geometry of the integrated column water vapor field. Specifically, the column water vapor field would have to be a self-affine surface with a roughness exponent H=0.4. Coincidentally, H=0.4 is the prediction of the Kardar-Parisi-Zhang universality class in two dimensions.I analyze the statistics of precipitation clusters and the column water vapor field in observations (using data from CMORPH and ERA5) and thirteen one-year global simulations performed with the ICON model at a horizontal resolution of 10 km. The simulations differ for example in their forcing (RCE or realistic forcing), in their rotation (no rotation, real rotation, constant Coriolis parameter), in their sea surface temperatures (SSTs; realistic and with land, zonal mean with land, constant without land, latitudinal gradient without land) etc. They are designed to test how robust the scaling laws of precipitation and column water vapor are.What changes drastically between the simulations is the probability density distribution of points in the phase space of column water vapor and tropospheric bulk temperature. This distribution occupies a very narrow space in the RCE simulations, but a very wide space in the realistic simulation with land. The critical column water vapor, where precipitation starts to occur, is approximately a linear function of temperature. It turns out that the column water vapor axes and the temperatures axes can be rescaled so that the onset curves of all simulations collapse onto one line (approximately). The results show that there is a good match with the observed scaling in most simulations, with the control simulation (realistic SSTs and land) showing the closest match. I speculate what the results may imply for interpreting observed scalings based on the Kardar-Parisi-Zhang equation.
Control technology of gully sediment yield in Yellow River basin
Authors: shen zhenzhou
Published: February 2023

The ecological protection and the high quality of national strategic in the Yellow River is pointed out that the Yellow River basin management to adhere to the concept of Lvshui Qingshan is the Jinshan Yinshan, strive to strengthen management of ecological protection, promote the implementation of a batch of major ecological restoration and construction projects, including Pisha stone areas in the middle reaches of the Yellow River is to focus on one of the areas to carry out the comprehensive control of ecological. Based on the analysis of the previous treatment theory and practice in the Pisha stone area, the research and development of the ecology-economy comprehensive treatment technology in the Pisha stone area is carried out. Including slope runoff efficient reservoir and utilization technology, the top economic fruit industry mode, block polymer grouting treatment technology of gravity erosion, slope erosion resistance and comprehensive treatment technology, flexible dam-Pisha stone channel modification material check dam and warping DAMS erosion prevention and control technology research and development and integration, finally enhance sieved Pisha stone areas are summarized ecological comprehensive control mode. The comprehensive ecological management model of Pisha stone can provide strong technical support for ecological protection and high-quality development of the Yellow River Basin.
Rate-Induced Tipping of the Compost Bomb: Sizzling Summers, Heteroclinic Canards and Metastable Zombie Fires
Authors: Mulchrone Kieran , O'Sullivan Eoin , Wieczorek Sebastian
Published: February 2023

The Arctic is the fastest warming region on Earth. Understanding how a rapidly changing climate change impacts Arctic systems is therefore an important challenge. This is the basis of the `Compost-Bomb' instability, a theorized runaway heating of northern latitude peat soils when atmospheric temperature rises faster than some critical rate, first proposed in [Luke & Cox, European Journal of Soil Science (2011), 62.1] and analysed in [Wieczorek et al, Proceedings of the Royal Society A (2011), 467.2129]. The Compost Bomb instability was one of the first examples of what is known as Rate-induced tipping or R-tipping.The key trigger for the compost bomb instability is heat produced by microbial respiration. Here, the original soil carbon and temperature model of Luke & Cox is augmented with a non-monotone microbial respiration function, for a more realistic representation of the process. This gives rise to a meta-stable state, reproducing the results of [Khvorostyanov et al, Tellus (2008), 60B] where a complex PDE model is used. Two non-autonomous climate forcings are examined: (i) a rise in mean air temperature over decades (ii) a short-lived extreme weather event, with the rate-induced compost bomb observed in each. Using techniques of compactification, singular perturbation theory and desingularisation, we reduce the R-tipping problem to one of heteroclinic orbits, uncovering the tipping mechanism for each climate change scenario.
Geochemical and isotopic study of Tramutola thermal water (High Agri Valley, Southern Italy): Interaction between crustal and mantle fluids
Authors: Zummo Filippo , Buttitta Dario , Caracausi Antonio , Paternoster Michele
Published: February 2023

The southern Apennines are affected by great crustal deformation and tectonic activity, where fluids from different reservoirs mix and rise to the surface through fault structures. Tramutola well (TRW) is an old borehole built by ENI, with the occurrence of bubbling gases located in the High Agri Valley (HAV), Southern Italy. The HAV is an inter-montane basin of the southern Apennine chain characterized by complex geological setting and high seismicity, this area hosts also the largest onshore Western European oil field. TRW is about 400 m deep it crosses clays, silicic clays and silicic limestone and is characterized by the continuous emission of thermal water (28°C) and bubbling gas. The water belong to Na-HCO3 hydrofacies.  TRW gases are CH4-dominated (82,6 %), and low amounts of N2 (12,9%), CO2 (1,7%), C2H6 (0,3%). The noble gases are used to discriminate the fluids origin (atmospheric, crustal and mantle). The 4He/20Ne ratio values are in three orders of magnitude higher that air-one (0,318) and 40Ar/36Ar ratio it is about 320 (Air=295.5; Hilton and Porcelli, 2003), this confirm the atmospheric contribution is present. Value Helium isotope (3He/4He, expressed as R/Ra) is between 1,13 and 1,26 Ra, and indicate a radiogenic component with a contribution of a mantle-derived helium (~20%). Methane isotope composition indicates a likely microbial isotopic signature (δ13C-CH4 =-63‰, δD-CH4= −217‰), probably due to either (1) biodegradation processes of thermogenic hydrocarbons or (2) ongoing microbial methanogenesis in the shallow organic‐rich clays hosting the gas. The δ13C-CO2 value between of -3.5‰ and -6‰ VPDB, consistent with a mantle origin. The gases have low CO2/3He ratios compared to mantle carbon end-member, probably due to secondary processes such as calcite precipitation. In conclusion, at Tramutola well have three gas sources and their possible mixing processes: (1) Shallow source, highlighted by atmospheric gas and rainwater entering the system through water infliltration; (2) crustal sources, CH4-dominant gas sources in correspondence of the hydrocarbon reservoir; (3) SCLM mantle source, mantle-derived fluids uprising through lithospheric normal faults.
Monitoring and Assessment of Global Patterns of Subnational droughts using Combined Drought Indicator and Geocoded Disaster Dataset
Authors: Kulkarni Sneha , Sawada Yohei
Published: February 2023

Agro-climatological droughts have been a dominant driver of various socio-economical losses. However, the association between drought hazards & their socio-economic impacts is still less explored on a global scale. The objective of this study is to understand this linkage by globally analyzing drought hazards and their socio-economic impacts during 2001-2021.To monitor the agro-climatological drought hazard, we have developed a new combined drought indicator (CDI) integrating satellite and reanalysis model-based four input variables (i.e., precipitation- CHIRPS data, temperature, and soil moisture – ERA5-Land data, normalized difference vegetation index – MODIS data). In CDI, the Principal Component Analysis was applied to combine all the variables. To examine the socio-economic impacts of drought hazard, we used the Geocoded Disaster (GDIS) dataset, which provided the location information of subnational-level drought events. Since GDIS shows the actual impact of drought events on socio-economic conditions, the drought vulnerability at a sub-national level can be quantified by performing a comparative analysis between CDI and GDIS.Based on CDI, the maximum frequency of severe drought events (> 7) is observed over sub-Saharan Africa, followed by parts of south Asia. During these events, the CDI values ranged between -1.5 to -3, signifying the critical hydrometeorological conditions in the respective region. The comparative analysis shows that the CDI-based drought clusters can represent the GDIS drought events at a statistically significant level. Both CDI and GDIS methods noticed that the parts of Argentina, Brazil, the horn of Africa, western India, and north China are continuously under the grips of severe droughts. In these regions, even less severe agro-climatological (CDI) droughts have caused substantial socio-economical (GDIS) losses making these areas highly vulnerable to drought. In contrast, the outcomes of CDI also indicated extreme drought cases over parts of North America and Europe, but these events were inconsistent with GDIS, meaning that developed countries are less vulnerable to drought.This study highlighted the importance of GDIS data for accurate drought impact assessment at the subnational level and in validating CDI. The proven subnational level association between CDI and GDIS from this study could help to identify the socio-economically vulnerable areas to drought on a finer scale and priorities the regions that demand more concern. 