bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigating Deep Convective Cores Combining CloudSat Observations and Model Simulations 
Authors: Xu Zhuocan , Kollias Pavlos , Battaglia Alessandro , Treserras Bernat Puigdomènech , Marinescu Peter
Published: March 2024

The launch of the joint ESA JAXA Earth Cloud Aerosol and Radiation Explorer (EarthCARE) mission (May, 2024) marks the beginning of a new era of spaceborne radar measurements that target atmospheric convection. In addition to the EarthCARE mission that features the first Cloud Profiling Radar (CPR) with Doppler capability, NASA’s Investigation of Convective Updrafts (INCUS) and Atmosphere Observing System (AOS) missions aim to provide unique observations of convective dynamics. Prior to this upcoming decade of the study of atmospheric convection from space, the CloudSat CPR collected remarkable data of convective cores over a period of 15 years. Despite its high frequency that results in significant attenuation and multiple scattering effects, the 94-GHz CloudSat CPR offers a relatively small footprint (compared to the TRMM/GPM radar footprint of 5 km) and collocated radar-radiometer (passive) brightness temperatures (Tb). Here, we propose a refined deep convective core (DCC) identification scheme by first selecting the CPR profiles with continuous echoes between below 2 and above 10 km. The 10-dBZ echo top height is also required to exceed 10 km and located within 2 km from cloud top. Additionally, profiles with stratiform precipitation flags in the CloudSat products are not included in the analysis.We investigated the CloudSat observations from 2006 to 2019 globally and also with a focus over 4 convective basins where model simulations are performed by the NASA’s INCUS science team. The four deep convection basins are Amazon, Congo, Philippines, and Western Pacific, which represent a decent spectrum of atmospheric environments. It is found that the DCCs over the Congo basin are featured with larger size and likely more intensified updrafts, while the Western Pacific is characterized with finer-scale cores. The analysis shows that the DCCs with size below 5 km predominate, implying the narrow cores can be under detected by the large-footprint radars such as GPM. The distinct depressions of 94-GHz Tb due to the presence of high-density ice particles lend complementary information on DCC classifications. In addition, multiple scattering can be a confounding factor in interpretating the CPR measurements within deep convective clouds. Our preliminary calculations suggest the impact of multiple scattering becomes significant at ~2.5 km from radar cloud top on average and is subject to the DCC updraft intensity. Moreover, profiles of 94-GHz radar reflectivity and Tb are forward calculated from the high-resolution model simulation outputs to understand the constraints that such observations can afford on key measures such as convective mass fluxes.
Bank Strength Variability controls the system-scale Morphodynamics of the Solimões River, Brazil
Authors: Aalto Rolf , Brückner Muriel , Best Jim , Paes de Almeida Renato , Nicholas Andrew , Ashworth Philip , Ianniruberto Marco
Published: March 2024

Large anabranching lowland river banks comprise sediments of varying strength, resulting from erosional and depositional processes that act over geological timescales. Although bank strength variability is known to affect channel morphodynamics, it often remains unquantified and its effect on the migration of large sand bed rivers is poorly understood. Measurements from a ~100 km long reach of the Solimões River, the upstream part of the Brazilian Amazon River, show that cohesive muds in Pleistocene terraces along its right bank have bank strengths up to three times greater than Holocene floodplain deposits that comprise the left bank. Image analysis reveals that these resistant outcrops control channel-bar dynamics: channel widening and bar deposition are inhibited, which reduces topographic forcing and stabilizes the opposing erodible bank. Analysis of the 1,600 km long Solimões River shows that where the channel is associated with older terraces, lower rates of bank erosion and deposition rates between 1984-2021 are evident. In locations where the channel has migrated away from the resistant terrace, further change analysis finds that channel has a strong tendency to rapidly migrate back. Analysis of water surface slope for the Solimões River finds scant correlation between water gradient and migration. Bank strength heterogeneity is thus the primary control on the large-scale morphodynamics of the world’s largest lowland river.
Evaluating the Interplay Between Soil Moisture and Meteorological Drought Indicators: Implications for Drought Monitoring and Crop Productivity in India
Authors: Behera Subhrasita , Dutta Debsunder
Published: March 2024

Drought is a recurring and complex climatic event that can severely impact various sectors, including agriculture. Agricultural drought assessment typically focuses on the deficiency of soil moisture during the growing season, while meteorological drought pertains to below-average precipitation over several months to years. However, there has been limited comprehensive comparison of satellite-derived agricultural and meteorological drought indices to assess their effectiveness in monitoring drought across India's different climate regions and cropping seasons (Kharif and Rabi). Drought conditions often lead to a significant decrease in gross primary productivity (GPP). To understand the impact of drought on plant growth, we utilized GPP as an indicator. Our analysis focused on examining the relationship between various vegetation stress indicators, including SPEI-3 (Standardized Precipitation Evapotranspiration Index), Root Zone Soil Moisture (RZSM), and GPP. In most regions of India, RZSM outperformed SPEI-3 in identifying vegetation stress conditions. Additionally, we conducted a spatial correlation analysis between each stress indicator and GPP, aiming to monitor changes in these correlations over time, particularly in different climate zones. The goal of this analysis was to assess how well stress indices consistently describe crop conditions across different time points and regions in India. Pearson's correlation coefficients were calculated for each month spanning the years 2014 to 2018. These calculations encompassed all pixels, comparing pairs of GPP and the respective stress indices within specific climate zones. Results from the analysis provide valuable insights into how the strength of correlation varies over time, considering variations across different months and years and differences in climatic zones across India's crop-growing areas. Further, insights will be presented on how these stress indicators are performing across major growing seasons and their spatial variation.
Bayesian network based evaluation and comparison of the urban flood risk factors for the 2016 flood and a 100-year return period flood event in Baton Rouge, Louisiana 
Authors: Hasan Fuad , Kameshwar Sabarethinam , Mostafiz Rubayet Bin , Friedland Carol
Published: March 2024

The study focuses on evaluating and comparing different flood risk factors that correlate with each other and affect the probability of flooding. Previous research is limited to identifying these factors’ influence on specific flood events. In contrast, buildings are constructed based on design flood maps, such as the 100/500-year return period flood map in the United States. Therefore, it is important to compare risk factors obtained from historical events and flood maps to identify any missing flood risk factors. To this end, a study was conducted to determine the difference between the probability of flooding and associated factors from a historic 2016 flood event in Baton Rouge, Louisiana, with the 100-year return period Federal Emergency Management Agency (FEMA)  flood map using a Bayesian network. The Bayesian network approach was used for this study due to its transparent forward and backward inference capabilities. The potential flood risk factors (population, household income, land cover, race, rainfall, river, and road proximity, and topography) were identified and corresponding data was preprocessed in ArcGIS to convert them as raster files of the same extent, and coordinate system. The factors were also classified based on different approaches (i.e., equalization, percentile, k-means clustering, etc.) to identify the most suitable classification method. A likelihood maximization-based parameter learning approach was used to obtain the conditional probability tables in the Bayesian network. This approach was used to develop separate Bayesian networks for the 2016 flood and the 100-year flood map. After setting up the Bayesian networks, sensitivity analysis, influential strength, and correlation matrix were generated, which were used to identify the most important flood risk factors. E.g., it was observed that land cover,topography, and river proximity are highly influential to the probability of flooding.
A web-based watershed delineation tool and its application to delineate 24,000 watersheds across Canada
Authors: Okubadejo Kasope , Mai Juliane , Basu Nandita B.
Published: March 2024

Watershed delineation is the identification of the boundary of a drainage basin, representing the contributing area for a specific outlet. This application of hydrography is essential in the analysis of watershed behaviour and has historically been performed manually. The automation of delineation provides faster and more consistent results which can be more accurate and reproducible definitions of borders compared to the results of the manual delineation. There is a wide range of software and tools capable of performing watershed delineation automatically; all generally following the same steps – utilizing conditioned DEMs to create flow direction and accumulation rasters used in addition to a specified pour point that defines the extent of contributing area desired. These different tools and their results have been explored, addressing their similarities, contrasts, and complications. Using this analysis, selected methods have been included in a web application for watershed delineation for users to either delineate individual points selected on a web map or upload lists of points of interest The automatically delineated watersheds are then made available for download. One tool has been deemed most applicable and has been used to delineate more than 24,000 watersheds across Canada successfully. The presentation will include (1) the results of the comparison of the various tools tested, (2) a demonstration of the webtool as well as (3) the presenting the results of the large scale delineation task across Canada.
Rock Magnetic and Mineralogical Analysis of IODP Expeditions 390 and 393 Basement Cores and their Implications for Fluid-Rock Interaction along the Mid-Atlantic Ridge Flank  
Authors: Hong Gilbert , Lee Sang-Mook ,   The South Atlantic Transect IODP Expedition 390 & 393 Scientists
Published: March 2024

During the International Ocean Drilling Program (IODP) expeditions 390 and 393 - also referred to as the South Atlantic Transect (SAT), basement cores have been drilled from a total of 6 holes which penetrates around 150 – 300 meters of the uppermost South Atlantic seafloor. The cores mainly consist of basalts of varying age (~7 to 61 Ma) and alteration states. Some intervals of sedimentary breccia were found in older cores as well. Analyzing how these rocks have been altered and characterizing it based on age and depth are crucial to understanding how the oceanic crust along the South Atlantic has evolved throughout spreading and how fluid-rock interaction has influenced the process. Magnetic minerals can be a useful proxy of such alteration as its effects can be observed in both rock magnetism and mineralogy.   In this study, we observed the composition and microstructure of magnetic minerals within basaltic samples of varying alteration degrees using a scanning electron microscope (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS). These observations were then compared with shipboard rock magnetic data to determine which property shows correlation with the mineralogical characteristics. Magnetic minerals within the SAT basalt samples are mostly titanomaghemites with Fe content of 20 – 36 at% and Ti content of 5 – 13 at%. Ti content is generally lower in more altered samples, with some highly oxidized samples showing very low percentage (< 3 at%). In addition, heavily altered samples show smaller (< 3 μm) and elongated magnetic mineral grains. Such mineralogical properties show correlation with key rock magnetic properties such as magnetic susceptibility and coercivity of remanence (Bcr). It is also notable that samples with high alteration degree also show reversals in remanence directions caused by strong secondary magnetization that persists after 20 mT demagnetization. This finding implies that production of secondary magnetic minerals may have occurred along with the oxidation of existing grains during the alteration of basalts.
 Simulations of pollen in North American and their influence on climate
Authors: Steiner Allison , Zhang Yingxiao , Schnell Jordan , Brooks Sarah
Published: March 2024

Pollen is one type of bioaerosol emitted in large quantities from many northern hemisphere vegetation types and has known impacts on human health and climate. A pollen emissions model accounting for 13 of the most prevalent types of pollen in North America is used to simulate emissions in the present day and the future and estimate concentrations with time.  Model simulations are evaluated with both ground-based pollen counts and remote sensing techniques to understand the seasonal timing of different pollen emission types and their relevance for climate.  Additionally, pollen grains can rupture and create smaller, subpollen particles that can influence cloud formation as cloud condensation nuclei and ice nucleating particles. Simulations indicate that the subpollen particles enhance cloud microphysical processes more than intact pollen grains by influencing the spatial extent and vertical structure of convective systems.  We evaluate the uncertainty of how estimated versus observed rupture rates and find that simulated SPP impacts are intensified when incorporating laboratory measured pollen rupture rates. 
Forecasting of rainfall-induced landslides in pyroclastic soil deposits through hydrometeorological information.
Authors: Abdullah Abdullah , Marino Pasquale , Roman Quintero Daniel Camilo , Greco Roberto
Published: March 2024

Shallow landslides pose a major geohazard impacting mountainous regions all around the world, and wide slope areas in Campania (southern Italy) covered by loose granular deposits overlapping a karstic bedrock are known for hosting the most destructive landslides of the region in the last decades. The landslide triggering factor in this case is clearly the rainfall. Nonetheless, there are concurring causes linked to the hydrological conditions predisposing slopes to failure (Bogaard and Greco, 2016). In the present study, the landslide-inducing factors are divided in static and dynamic (Moreno et al., 2023). The static factors (e.g., topography, slope, forest ratio) are well investigated in numerous studies on landslide susceptibility assessment. However, the modelling of dynamics factors (e.g., rainfall, soil moisture) is a relatively new issue and has been addressed only in few studies. In this study, Generalized Additive Models (GAMs) were applied for spaciotemporal data-based modelling of landslide prediction for eleven years (2010-2020). The study area is located on the Sarno and Partenio mountains in Campania where pyroclastic soil deposits cover about 370 km2 of carbonate massifs. In a first step, the modelling of static components, controlling landslide susceptibility in the area, was carried out by utilizing the historical data of landslide events along with other factors (slope, forest ratio etc.,) significantly affecting the static probability of landslide occurrence. Afterwards, the dynamic component was modelled by considering the triggering rainfall and the antecedent soil moisture for landslide events. The soil moisture data was taken from ERA5-Land soil moisture product. Lastly, the static and dynamic components were integrated to model the dynamic probability of landslide occurrence. A cross-validation technique was used for model training. The novel integrated model approach showed trustworthy improvements in the assessment of the probability of landslide. The model was also successfully tested for different rainfall events reproducing the landslide triggering conditions in the study area.
Sub-Lithospheric Small-Scale Convection as a Window into the Asthenosphere: Insights from Integrating Models Of Mantle Convection, Grain Size Evolution and Seismic Tomography
Authors: Dannberg Juliane , Eilon Zachary , Russell Joshua B , Gassmoeller Rene
Published: March 2024

Understanding the interaction between oceanic plates and the underlying asthenosphere and its impact on plate thickness is essential for explaining plate motions and mantle convection patterns. While sub-lithospheric small-scale convection provides an explanation for why oceanic plates do not continue to thicken after a certain age, many open questions still surround this process. Here, we link dynamic models of mantle flow, grain-scale processes, seismic imaging, and surface observations to gain new insights into the mechanisms of asthenospheric small-scale convection and its surface expressions.We have performed a series of high-resolution 3D numerical models of the evolution of oceanic plates and the development of thermal instabilities at their base using the open-source geomodeling software ASPECT. These simulations use an Earth-like rheology that includes coupled diffusion and dislocation creep as well as their interplay with an evolving olivine grain size. Our models quantify how the effective asthenospheric viscosity and the balance between diffusion and dislocation creep affect the morphology and temporal stability of small-scale sub-lithospheric convection, including the age of its onset, the average depth and wavelength of the small-scale convection rolls, and the amplitude of the temperature and grain size anomalies within the rolls.All of these quantities predicted by the dynamic models can be directly related to both geophysical observables and to surface manifestations such as dynamic topography and heat flux. To accurately compare our model outputs to geophysical data, we convert them to seismic velocity and attenuation using laboratory-derived constitutive relations and taking into account variations in temperature, pressure, grain size, water content and calculated stable melt fraction. We then create synthetic seismic tomography models of different dynamic scenarios and analyze their fit to observations from the Pacific OBS Research into Convecting Asthenosphere (ORCA) experiment. Comparison with both seismic imaging and surface expressions allows us to determine the parameter range in which geodynamic models fit these observations, providing new constraints on the convection patterns and the rheology of the oceanic asthenosphere beneath the Pacific Plate.
Linkage of 137Cs dynamics in river and coastal seawater during high-flow events
Authors: Wakiyama Yoshifumi , Satoh Shun , Takata Hyoe , Chaboche Pierre-Alexis , Kurosawa Honoka
Published: March 2024

Previous studies indicated that high-flow events can result in substantial 137Cs exportation via river to the ocean and increase 137Cs concentrations in coastal seawater. Assessing response of marine 137Cs behavior to terrestrial 137Cs inflow will lead to a better understanding of 137Cs transfer processes in terrestrial and marine environments. This study presents results of sample collections under various flow conditions on a river system and its coastal seawater to discuss the transfer processes in detail. The study was conducted in the Ukedo river system and its coastal sea during 3rd-19 th September 2023. Water samples were collected for 13 times at two downstream points of the river system, on the mainstream (Ukedo river) and a tributary (Takase river), and 8 times at seashore locating at 500 m north from the river mouth. In the sampling period, the catchment mean rainfall was totaled 300 mm with intensive rainfalls on 4, 6 and 8 September. Collected water samples were filtrated to measure 137Cs concentration in suspended solids (Bq/kg) and dissolved 137Cs concentrations (Bq/L). 137Cs concentrations in suspended solids in Ukedo and Takase river ranged from 7.0 to 67 kBq/kg and from 2.4 to 15 kBq/kg, respectively. The concentrations at peak water discharge phases in Takase river tended to be high when ratio of rainfall amount on downstream parts to that on whole catchments were high, but vice versa in the Ukedo river. This discrepancy can be attributed to the difference in spatial distribution of 137Cs inventory between the two catchments. Dissolved 137Cs concentrations in Ukedo and Takase rivers ranged from 52 to 70 mBq/L (5 samples measured out of 13) and from 8.4 to 37 mBq/L, respectively. At the seashore, 137Cs concentrations in suspended solids and dissolved 137Cs concentration ranged from 2.0 to 95 kBq/kg and from 6.7 to 410 mBq/L, respectively. Both concentrations appeared maximum in the sample collected 5 hours after the peak river water discharge which occurred with intensive rain on 8th September. Higher dissolved 137Cs concentration in seawater than in corresponding river water for the high-flow event indicates considerable desorption of 137Cs from terrestrial suspended solids into coastal seawater. Both 137Cs concentrations in seawater decreased with time to reach the background levels in 10 days after the event despite of quite stable concentrations in rivers. These results provide important implications for quantifying 137Cs transfer processes in terrestrial-marine environments.
The thermal response of lake surface water temperature to atmospheric heatwave
Authors: Li Yulu , Zhao Gang , Tang Qiuhong
Published: March 2024

The sensitivity of lake surface water temperature (LSWT) to atmospheric warming has been well-established due to rapid sensible heat exchange. However, the specific impact of discrete heatwave events on LSWT dynamics, including their magnitude and persistence, remains poorly understood. To address this gap, we comprehensively analyze changes in LSWT during atmospheric heatwave events across a global network of 16,609 lakes. LSWT data are derived from Landsat 5, 7, 8, and 9 satellite imagery spanning 1985 to 2021, while heatwave intensity is quantified using hourly air temperature data from the ERA5-Land reanalysis. Our analysis identifies and characterizes heatwave events and their associated LSWT changes for each lake during the study period. Key findings reveal: (1) A widespread increase in both heatwave intensity and LSWT change across the majority of lakes, highlighting a concerning intensification of coupled air-water warming trends. (2) Significant spatial heterogeneity in LSWT sensitivity to heatwaves is observed. Notably, a pronounced memory effect is detected in LSWT response to heatwaves, suggesting a lingering influence of atmospheric heat events on lake energy balance, with implications for ecosystem stability and resilience.
Center strategies for universal geodetic transformations: modified iteration policy and two alternative models
Authors: Zhan Wenxi , Fang Xing , Zeng Wenxian
Published: March 2024

Although centralized coordinates are applied in geodetic coordinate transformations implicitly or explicitly, the centering strategy has not been comprehensively investigated from the theoretical perspective. We rigorously model and extend the empirically used three center strategies based on different models:Original model: Based on the partition representations of the solution, we propose a modified iteration policy, which reduces the parameter number and improves numerical stability during iteration. Also, its simplified version is analyzed when the cofactor matrix has the Kronecker product structures. It can be regarded as the extension of the work of Teunissen, since we essentially follow the same idea of partitioning the transformation parameters and the translation parameters, but more general covariance matrix structures are investigated in our consideration.
Shifting model: With the partitioned solution forms, we prove the estimated transformation matrix and the residual vector are translational invariant. For iteration, with the classical iteration policy, the shifts should be chosen properly; with the modified iteration policy, there is no restriction since it is numerically equivalent to the original model. In addition, this model shows the feasibility of conducting the adjustment with the centralized coordinates and the original stochastic model.
Translation elimination model: By multiplying the transformation relation with a specific matrix from both sides, we formulate the translation elimination model with the coordinates centralized and the translation parameters eliminated. With this model reduction, the covariance matrix has also been transformed since the observation equations are comprised of coordinate combinations. In addition, Leick’s model reduction strategy is a special case of this model, which is conducted by subtracting one particular observation equation from the remaining equations. 
Test computations with different weight structures show the validity of these strategies.
Multi-scale interaction and predictability of moist convection and tropical cyclones 
Authors: Minamide Masashi , Posselt Derek
Published: March 2024

Predicting tropical cyclone intensity changes, especially the onset of rapid intensification, has been a more challenging topic than tropical cyclone tracking because of its chaotic nature in multi-scale physical process with significant contributions from convective-scale phenomena. Before intensification onset, tropical cyclones experience precession process, in which tilted vortices rotate counterclockwise around the center of circulation, and develop an axisymmetric structure. The forecast uncertainty in precession process limits the predictability of early-stage development and intensification of TCs.In this study, we have explored the contribution of moist convective activity to the predictability and variability of TC intensification onset through the precession process. Our recent investigation in Minamide and Posselt (2022) proposed a Lagrangian-based approach to identify the potential signals of individual convective occurrence. Using the technique, we conducted sensitivity experiments to control specific convective activities within the inner-core of early-stage TCs with convection-permitting Weather Research and Forecasting model (WRF-ARW). The results indicate that the spatiotemporal variability of convective activity even governs whether early-stage vortex completes precession and initiates RI, indicating the importance of accurately constraining convective activity in the severe weather event predictions. Given the strong nonlinearity of the onset process of RI, the advancement of our understanding of the uncertainty sources will provide an insight about the observation network that may effectively constrain the TC forecasting.
Stratospheric residence time and the lifetime of volcanic stratospheric aerosols
Authors: Toohey Matthew , Jia Yue , Khanal Sujan , Tegtmeier Susann
Published: March 2024

The amount of time that volcanic aerosols spend in the stratosphere is one of the primary factors influencing the climate impact of volcanic eruptions. Descriptions of stratospheric aerosol persistence vary, with many works quoting an approximately 1-year residence time for aerosol from large tropical eruptions, but other references to 1-2 year “lifetimes”. We introduce a framework for describing the evolution of global stratospheric aerosol after major volcanic eruptions and assess its persistence, based on analysis of global satellite-based aerosol observations, tracer transport simulations and simple conceptual modeling. We show that stratospheric residence time, which is estimated through passive tracer pulse experiments and is one factor influencing the lifetime of stratospheric aerosols, is strongly dependent on the injection latitude and height, with an especially strong sensitivity to injection height in the first four kilometers above the tropical tropopause. Time series of simulated stratospheric tracer fraction are best described by a simple model which includes a lag between the injection and initiation of removal from the stratosphere. A simple model including lagged decay, as well as a timescale for sulfate aerosol production, produces a best fit to global observations of stratospheric aerosol after the 1991 eruption of Mt. Pinatubo consistent with a stratospheric lifetime of about 24 months. We estimate the potential impact of observational uncertainties on this lifetime estimate and find it likely that the lifetime of Pinatubo stratospheric aerosol is 20 months or greater. 
Vertically resolved analysis of the Madden-Julian Oscillation highlights the role of convective transport of moist static energy
Authors: Yang Da , Hannah Walter , Yao Lin
Published: March 2024

We simulate the Madden-Julian oscillation (MJO) over an aquaplanet with uniform surface temperature using the multiscale modeling framework (MMF) configuration of the Energy Exascale Earth System Model (E3SM-MMF). The simulated MJOs have similar spatial structures and propagation behavior to observations. To explore the processes involved in the propagation and maintenance of the MJO, we perform a vertically resolved moist static energy (MSE) analysis for the MJO (Yao, Yang, and Tan 2022; Yao and Yang 2023). Unlike the column-integrated MSE analysis, our method quantifies how individual physical processes amplify and propagate the MJO’s characteristic vertical structure. We find that radiation, convection, and boundary layer processes all contribute to maintaining the MJO, balanced by the large-scale MSE transport. Furthermore, large-scale dynamics, convection, and boundary layer processes all contribute to the eastward propagation of the MJO, while radiation slows the propagation. We further show that the MJO can still self-emerge when radiative heating rate is horizontally homogenized, highlighting that convective and boundary-layer MSE transports are sufficient to sustain the MJO. These transport processes might be overlooked in the column-integrated MSE analysis.
A urea-based symbiotic transfer of nitrogen in biological soil crusts
Authors: Heredia-Velasquez Ana Mercedes , Sarkar Soumyadev , Warsop Thomas Finlay , Garcia-Pichel Ferran
Published: March 2024

Crucial to the establishment of biological soil crusts is a mutualistic exchange of C for N between pioneer filamentous non-heterocystous cyanobacteria of the Microcoleus type and a selected group of heterotrophic diazotrophs (for example, Massilia sp.) that come together in the so-called “cyanosphere”. In other such C for N mutualisms, N is transferred between species in the form of amino acids, and potential losses to adventitious bacteria are prevented by sequestering the diazotrophs into specialized structures. Yet, in the Microcoleus symbiosis no such structures exist, and only proximity achieved through chemotaxis is known to optimize the exchange. How is specificity then achieved?  We posited that the exchange might occur through urea, because it is the preferred N source for growth in Microcoleus. We show using cultures that members of the cyanosphere excrete urea when growing in symbiosis with Microcoleus at low concentration but sustained rates, but not when growing on their own diazotrophically. Consistently, Microcoleus can grow on urea down to the micromolar range, unlike other cyanobacteria that need much higher concentrations to grow. We also show that Massilia overexpresses the genes for the urea cycle (production of urea) when in symbioses, but not otherwise, and that Microcoleus overexpresses genes for urea uptake and utilization when in symbiosis. Microcoleus contains a rare set of enzymes for urea utilization (allophanase and urea carboxylase), that, unlike the widespread urease, allow it to process urea at very low concentrations. Hence, it seems that with the combination of these unique biochemical and regulatory capacities, low concentration urea can effectively transfer N in a partner-specific way, dodging potential losses of N to most other bacteria that can only use urease. We discuss the importance of these findings for the ecology and restoration of biological soil crusts. 
Zero-shot learning of aerosol optical properties with graph neural networks
Authors: Lamb Kara , Gentine Pierre
Published: March 2024

Black carbon (BC), a strongly absorbing aerosol sourced from combustion, is an important short-lived climate forcer. BC’s complex morphology contributes to uncertainty in its direct climate radiative effects, as current methods to accurately calculate the optical properties of these aerosols are too computationally expensive to be used online in models or for observational retrievals. Here we demonstrate that a Graph Neural Network (GNN) trained to predict the optical properties of numerically-generated BC fractal aggregates can accurately generalize to arbitrarily shaped particles, including much larger (10x) aggregates than in the training dataset. This zero-shot learning approach could be used to estimate single particle optical properties of realistically-shaped aerosol and cloud particles for inclusion in radiative transfer codes for atmospheric models and remote sensing inversions. In addition, GNN’s can be used to gain physical intuition on the relationship between small-scale interactions (here of the spheres’ positions and interactions) and large-scale properties (here of the radiative properties of aerosols).
SEM and TEM characterization of framboidal pyrite with jagged-like structure  in the Lower Cambrian Shuijingtuo Formation shale and its indication to early Cambrian dynamic ocean oxygenation
Authors: Song Hui , Zhang Tongwei , Shao Deyong , Meng Kang , Zhang Yu
Published: March 2024

Pyrite is widespread in modern and ancient shales, among them, framboidal pyrite has been paid more attention because its formation and oxidation are not only related of circulation of some elements such as S, Fe and O, but may reflect the evolution characteristics of the paleo-environment during the synsedimentary-early diagenetic stage. In this study, a continuous core well in the Lower Cambrian Shuijingtuo Formation, the Yangtze Plate, China was selected, and pyrite elaborate morphology at micro-nanometer scale was intensively investigated by using Ar ion milling-scanning electron micrography (SEM) technologies, and aberration corrected transmission electron microscope (AC-TEM). The results showed that the some pyrite framboids grains with jagged-like structure appeared in the upper part of the Shuijingtuo Formation. The oxygen content of framboids with jagged-like structure is higher than that of framboids with complete crystal grain based on EDS elemental data. These jagged-like pyrite grains displayed a series of oxidation byproducts as precipitated phases which are interpreted as marcasite, ferrous sulfate, and iron sulfate hydrate by means of HRTEM calibration. In some cases, about 5nm thick amorphous passivation layer occurred on the edge of pyrite grains. All of our observations indicate that the jagged-like structure of these pyrite framboids is likely caused by oxidation and dissolution during the synsedimentary-early diagenesis, and two scenarios are further suggested: In scenario 1, a passivation layer on the surface of pyrite framboids was formed at the beginning of pyrite oxidation, and in scenario 2, along with increasing oxidation extent and elevated Eh in pore water, the jagged-like structure was formed from the partial dissolution of pyrite framboids grains and the precipitation of oxidation byproducts resulted in an increased impurity of pyrite crystal pattern. Our observations are consistent with geochemical paleoenvironmental parameters. UEF , U/Th and V/Cr ratios record that there is intermittent oxygenation during the lower Cambrian organic-rich shale deposition. The discrepancy of morphology of framboidal pyrite microcrystalline is coincided with the diversification of redox indicators, turning into a kind of mineral indicator of seafloor and superficial sediment pore water oxidation. 
Key words: In-situ TEM; Framboidal pyrite; Pyrite oxidation; Jagged-like structure; Lower Cambrian
Water ponding timing, spatial distribution, and connectivity on soil surfaces measured by time-lapse imagery processed with deep learning
Authors: Zamboni Pedro , Lenz Jonas , Wöhling Thomas , Eltner Anette
Published: March 2024

Measuring runoff formation on soil surfaces by rainfall simulators predominantly provide lumped values without spatiotemporal information in regard to water dynamics (e.g., water ponding timing and connectivity).  Understating spatial and temporal variations of water storage on soil surface is key to assess hydrological connectivity and runoff generation. Furthermore, it is very relevant for erosion studies. Computer vision and deep learning has presented state-of-the-art results in environmental sciences, for instance to segment water using cameras as gauges or performing flood mapping with remote sensing images. However, automatic mapping of water forming on soil surfaces due to rainfall is very challenging because the water area is considerably smaller and water ponds present complex shapes and similar color characteristics to the soil itself, which is a challenge for deep learning models. The aim of this study is to assess the potential of computer vision and deep learning to estimate water ponding timing, connectivity and runoff formation behavior during rainfall simulations, with emphasis on data imbalance and label uncertainty.We conducted rainfall simulations at three different soil erosion plots with different soil and tillage caracteristics. Runoff was measured at the plot outlet. We collected time lapse images from the plot surface. And ground control points for model scaling were measured with a total station. To train the deep learning models, we manually labeled a selected set of images from all the plot images to derive binary masks (i.e., water and background). We trained three different convolution neural networks (CNN) and further considered techniques that take class imbalance and label uncertainty into account. Eventually, we assess the performance of ensemble models. We applied the best model on the whole set of time lapse images and measured the water pixel area and pond connectivity in terms of connected components. Our findings suggest that considering class imbalance and label uncertainty is key to reach satisfactory segmentation performance, being more important than the model architecture. Furthermore, ensemble models result in better performance when compared to single models. By comparing the measured discharge and the water area derived from the best deep learning model, we can observe different characteristics of the runoff formation related to distinct ponding and intensity of ponding and connectivity. Our approach presents an innovative visual and automatic observation option to quantify the water pond formation and its spatial temporal development. It is a step towards a better understanding of the runoff generation.
Future Projections of Summer precipitation-driving Mechanisms over the South American Altiplano
Authors: Agudelo Jhoana , Espinoza Jhan-Carlo , Junquas Clementine , Arias Paola A.
Published: March 2024

The South American Altiplano is a high-altitude plateau (3800 m MSL) located in the central Andes between 15ºS and 22ºS. Bounded to the west by the coastal desert of Peru-Chile and to the east by the hyper-humid lowlands of Peru-Bolivia, the Altiplano exhibits a semi-arid climate, following a pronounced annual cycle, with over 70% of rainfall occurring during the austral summer (December-January-February). Associated with factors such as convective activity occurring west of the Amazon Basin, the generation of convective clouds over the central Andes occurs when eastward winds encounter the orographic barrier on the eastern slope of the Andes. This process represents the primary mechanism governing precipitation variability in the Altiplano. Previous studies analyzing future projections anticipate that the central Andes will become warmer during the 21st century, impacting the population, ecosystems, and glaciers of the South American Altiplano. This is particularly relevant since agriculture is the main economic activity in this region and depends directly on precipitation.Summer precipitation over the Altiplano has shown a strong dependence on the magnitude of zonal flow in the free troposphere (200 - 300hPa). Nevertheless, General Circulation Models (GCMs) suggest a continuous increase in westerly flow over the central Andes, hindering moisture transport from the interior of the continent. Minvielle and Garreaud (2011) suggest a significant reduction (10%-30%) in Altiplano precipitation by the end of this century under moderate to strong greenhouse gas emission scenarios. More recently, Segura et al., (2020) found that precipitation variability in the Altiplano is also associated with upward motion over the western Amazon (WA). Thus, DJF precipitation over the Altiplano seems to respond directly and primarily to the upward motion over the WA, since the early 21st century.Using a set of 13 GCMs, this study aims to explore possible future projections in precipitation processes under the SSP3-7.0 scenario. This study focuses on the evolution of two previously established mechanisms driving austral summer precipitation over the Altiplano: 1) easterly winds at upper levels over the central Andes, and 2) upward motion over the WA. As preliminary conclusions of this work, models indicate that both mechanisms appear to weaken for the future period analyzed (2050-2084), suggesting a reduction in summertime precipitation by the mid-21st century. Additionally, models project a more stable atmosphere over the central Andes for the future period, also indicating a reduction in precipitation in the region, reinforcing the initial conclusion.
Overview of thermochronological studies in and around the Japan Arc; towards Thermo2025 Conference in Kanazawa, Japan
Authors: Tagami Takahiro , Hasebe Noriko , Sueoka Shigeru
Published: March 2024

Recent progress of low-temperature thermochronology enables to analyze uplift-exhumation-cooling histories of the island-arc mountains with good confidence. This is particularly fruitful for studying the topographic evolution of the Japan Arc, because many of the Japanese mountains are started to uplift in recent time (e.g., late Pliocene to Quaternary) after an extended period of tectonic quiescence, and hence the resultant amount of total denudation is relatively small. The utility of the approach was first demonstrated by elucidating the uplift-exhumation-cooling process for some of the Japan Alps, in which average topographic changes of the tilted mountain block were quantitatively reconstructed by low-temperature thermochronology (Ref. 1-2). Such analyses also allow to estimate the background paleo-depth of neo-tectonic faulting episodes.In this presentation, we highlight recent and ongoing important thermochronological research in and around the Japan Arc (Ref. 3-5). In addition, we will promote the Thermo2025 conference and introduce its preliminary plans. The International Conference on Thermochronology has been held biyearly around the world and the International Standing Committee on Thermochronology (ISCT) determined that the 19th conference (Thermo2025) will be held in Kanazawa, Japan, on September 14-20th, 2025 (https://isct.sedoo.fr/meetings-2/). Then, the local organizing committee, including the authors, have promoted the preparation of the conference in partnership with the domestic geoscience societies and international thermochronological communities. Pre-registration of Thermo2025 is now being accepted at the website (https://smartconf.jp/content/thermo2025). Those who are interested in the conference can soon receive the announcements by pre-registration.References1. Sueoka, S. et al. Island Arc 21, 32-52 (2012).2. Sueoka, S. et al. Journal of Geophysical Research: Solid Earth 122, 6787-6810 (2017).3. Sueoka, S. and Tagami, T., Island Arc 28, 1-8 (2019).4. Fukuda, S. et al. Earth Planet Space, 72, 1-19 (2020).5. King, G.E. et al. Geology, doi.org/10.1130/G50599.1 (2022).
New evidence for CH4 enhancement at upper troposphere associated with Asian summer monsoon
Authors: Cai Zhaonan , Tao Mengchu , Zhu Sihong , Liu Yi , Feng Liang , Fang Shuangxi , Yi You , Bian Jianchun
Published: March 2024

The Asian Summer Monsoon (ASM) region is key region transporting air to the upper troposphere, significantly influencing the distribution and concentration of trace gases, including methane (CH₄), an important greenhouse gas. We investigate the seasonal enhancement of CH₄ in the upper troposphere over the ASM region, utilizing retrievals from the Atmospheric Infrared Sounder (AIRS), model simulations and in-situ measurements. Both AIRS data and model simulation reveal a substantial seasonal increase in CH₄ concentrations of up to 3%, aligning with the active monsoon period. Notably, the spatial distribution of the methane plume demonstrates a southwestward shift in the AIRS retrievals, in contrast to the model simulations which predict a broader enhancement, including a significant increase to the east. A cross-comparison with in-situ measurements, including AirCore measurements over Tibetan Plateau and airline sampling across the Asian summer monsoon anticyclone (ASMA), favors the enhancement represented by model simulation. Remarkable CH4 enhancement over west Pacific is also evidenced by in-situ data and simulation as dynamical extension of ASMA. Our findings underscore the necessity for cautious interpretation of satellite-derived methane distributions and highlights the critical role of in-situ data in anchoring the assimilation of CH4.
Numerical exploration of the dynamics of the subduction plate boundary channel 
Authors: Wang Guanzhi , P. Morgan Jason , Vannucchi Paola
Published: March 2024

The plate ‘interface’ at subduction zones has often been idealized as a single fault with ‘asperities’, however there is increasing evidence that plate boundary motions typically occur across a ~100-1000m channel or shear zone. Here we investigate the dynamics of slip in a mechanically heterogeneous plate boundary shear zone, and will typically use periodic boundary conditions to model the channel at a ~m-scale.  In contrast to most previous numerical studies, we imagine that this shear zone is embedded within finite strength wall-rock associated with the downgoing and overriding plates that themselves are capable of subduction-related deformation, for example during bend-faulting of the lower-plate or a forearc deformation event. We first look at how stress-concentrations can form by the clogging of strong blocks in a channel with a weaker matrix. We find that the strength of the surrounding wall-rock will play a key role in the channel’s response to a clogging event. In general, a clogging event can be mitigated by failure of surrounding relatively weak wallrock along the edges of a subduction channel in the conceptual process put forward by von Huene et al. (2004) to drive basal erosion of the forearc. We also consider cases where metamorphic transitions have led to the existence of weaker blocks within a stronger matrix. In this case, frequent tremor-like failure of the weak blocks can coexist with rarer earthquake failure of the stronger surrounding matrix.  Finally we explore the mechanical effects of channel widening and narrowing events that will invariably lead to a component of local pressure-driven flow within a subduction shear channel. Numerical snapshots and videos are used to visualize these potential modes of subduction shear zone deformation.