bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of mesh resolution on accurate grounding line definition using 2D finite element software, Elmer/ice
Authors: Lim Su-jeong , So Byung-Dal
Published: February 2023

Marine ice sheet dynamics plays a key role in the mechanical interaction between glaciers and the ocean. A steady-state marine ice sheet, due to the buttressing force of ice shelves, suppresses the glaciers from discharging into the ocean. Various atmospheric-oceanic-glacial mechanisms such as ice melting, buttressing, and snow accumulation lead to the instability of marine ice sheets. The unstable marine ice sheet cause thinning ice thickness and the resultant ice shelf collapse. Ice shelf collapse accelerates the rapid glaciers discharge and retreats, directly affecting sea level rise. The positive feedback loop of these processes significantly influences the ice sheets dynamics, especially the advance and retreat of the grounding line. The grounding line can be defined as a transition zone between the grounded ice sheet in bedrock and the floating ice shelf due to water buoyancy. Understanding grounding line dynamics may help us predict marine ice sheet instability and future sea level rise. It has been challenging to determine an accurate grounding line in the numerical simulation of the marine ice sheet due to mesh resolution. Here we performed two-dimensional ice flow modeling using open-source finite element software (i.e., Elmer/ice), to quantitatively evaluate the effect of diverse mesh sizes on the position of the grounding line. We tested a series of numerical models to precisely define varying the grounding line position influenced by bedrock topography, snow accumulation, and ice melting. The models with high mesh resolution required short time steps to obtain the accurate grounding line position. To consider both calculation efficiency and the accuracy of the position of the grounding line, we found adequate time steps corresponding to each mesh size ambient the grounding line. Our systematic results can provide inspiration for choosing a suitable mesh size and time step to determine a more accurate grounding line position.
Understanding the relative importance of different precipitation generating weather systems and quantifying their efficiencies
Authors: McDonald Adrian
Published: February 2023

 Understanding rainfall and its extremes is essential for quantifying weather and climate related risks, and the management of water resources. However, climate projections of rainfall have large uncertainties because of differing sensitivities to changes in dynamic, thermodynamic and microphysical factors. Emergent statistical constraints derived from observations and high resolution simulations can be used to reduce these uncertainties, but must be based on process understanding to be robust.Our recent work shows that clustering rainfall data into regions of similar wet day frequency, regardless of geographical separation, uncovers a strong correlation between wet day occurrence and daily rainfall accumulation distributions. This relationship is robust across a range of observational datasets with differing spatial resolutions.We hypothesise that this relationship shows that the presence or absence of precipitation generating weather systems (atmospheric rivers, cyclones, fronts and mesoscale convective storms) rather than their individual intensities is critical for daily rainfall totals. In this presentation, we will first examine whether the probability of specific dynamic, thermodynamic and microphysical states drives wet day occurrence. We will also use feature analysis and tracking schemes to identify how the distribution of each of these dynamic, thermodynamic and microphysical states varies for each precipitation generating weather system. This potentially allows a quantification of the importance of different precipitation generating systems for different wet day occurrences and how each contributes to daily accumulation distributions. This expands on previous work which has shown that atmospheric rivers, cyclones, fronts and mesoscale convective storms have varying relationships to rainfall and their extremes. In particular, it allows us to identify their relative importance and explains their relative efficacy for precipitation generation.
Development of ice sheet model using COMSOL Multiphysics®: Comparison with Ice Sheet System Model (ISSM)
Authors: Baek Yi-Jeong , So Byung-Dal
Published: February 2023

Glacier mass loss related to ice flow is a quantitative factor that controls sea level rise and global warming. Ice flow is attributed to the complicated interaction between grounding line migration, calving basal friction, and topography. Previous studies using massive geophysical observation, including IPR (Ice Penetrating Radar), InSAR (Interferometric Synthetic Aperture Rada), and heat flow exploration, highlight the need to develop a sophisticated numerical model. Because it is difficult to numerically solve the full-stokes equation obtaining ice velocities, the simplified governing equation (i.e., HO, Higher Order model; SSA, Shallow Shelf Approximation; SIA, Shallow Ice Approximation) is widely used in the ice sheet dynamics community. The SSA approach, which assumes a depth-independent velocity model, has computational cost reduction based on simplified descriptions of the full-stokes equation. Here we developed the two-dimensional SSA numerical model to better understand ice dynamics using COMSOL Multiphysics® (hereafter COMSOL), which is a user-friendly finite element software providing convenient GUI, mesh generation, post-processing tools, various types of elements, and the order of shape function. To verify the application of COMSOL to ice sheet dynamics, we compared it with an open-source finite element package, Ice Sheet System Model (ISSM). The concise toy model successfully simulated the distribution of viscosity and velocity and the evolution of surface topography in both COMSOL and ISSM. Furthermore, we applied realistic bathymetry data (i.e., Bedmap2) of Pine Island Glacier, where the large ice mass loss occurs, to clarify more similarity of each model. The surface velocity patterns calculated by COMSOL and ISSM are significantly similar for various physical properties (e.g., ice viscosity, friction, and rate of accumulation and melt). We propose that COMSOL, which efficiently handles mesh generation and visualization, and various weak forms, can sufficiently be applied in ice dynamics.
Upper crustal anisotropy in the southeastern Korean Peninsula from shear wave splitting of local earthquakes
Authors: Baek June , Kang Tae-Seob , Heo Dabeen , Ree Jin-Han , Kim Kwang-Hee , Rhie Junkee , Kim YoungHee
Published: February 2023

Shear wave splitting (SWS) is a widely used technique to study the anisotropic properties of the Earth’s interior. The geological structure of the southeastern Korean Peninsula is represented as the Yangsan fault and Ulsan fault, which is controlled by the present-day compressional stress regime in the ENE-WSW direction. We analyzed shear wave splitting to understand the anisotropic features of the upper crust above the hypocentral depth in the southeastern Korean Peninsula using the local earthquake data from the Gyeongju Hi-density Broadband Seismic Network (GHBSN). The GHBSN is a dense array composed of 200 broadband stations, which covers an area of about 60×60 km2 in the southeastern Korean Peninsula. We used the MFAST program (Savage et al., 2010) to measure the SWS parameters of fast polarization and delay time from shear waves of local earthquakes from January 2019 to December 2020. In addition, the TESSA program (Johnson et al., 2011) was employed to inspect the spatial variation in the anisotropy of the study region. To obtain reliable measurements of SWS parameters, rigorous constraints including quality control of the original waveforms were applied, and then, cycle-skipped measurements were manually removed. In final, we obtained the SWS measurements of 4260 records. Because the seismicity in the region is concentrated at the epicentral region of the 2016 Gyeongju earthquake sequence and the hanging wall of the Ulsan fault, raypaths are limited to a narrow azimuthal range. Both the raw and spatially averaged fast-polarization directions are dominant to be parallel either to major faults (structural anisotropy) or to the ENE-WSW (stress-induced anisotropy). Also, some stations and regions show bi- or multi-modal rose diagram of the SWS, representing that there is more than one factor of anisotropy to induce the SWS. The delay time of the SWS showed the right-skewed distribution. Tomographic result of the SWS delay time shows that, relatively high anisotropy is observed at the epicentral region of the 2016 Gyeongju earthquake sequence and the hanging wall of the Ulsan fault. It implies that microcracks at these regions are better developed compared to the remaining regions.
A thermo-poroelastic finite element analysis of fluid injection depending on fluid temperature and injection scenarios
Authors: Jang Chan-Hee , Kim HyunNa , So Byung-Dal
Published: February 2023

Subsurface fluid injection of environmental (e.g., carbon capture storage) and industrial (e.g., enhanced geothermal system) projects change pore pressure and underground stress which may induce fault slip. The temperature of injected fluid controls pore pressure and underground stress by thermo-poroelastic effect of fluid injection, that explains the interaction between pore fluid flow and elastic deformation in a porous medium. Since the perturbed subsurface stress distribution increases seismic uncertainty, a numerical modeling for varying injection conditions (e.g., injection scenario and fluid temperature) is helpful for understanding thermo-poroelastic behavior before the fluid injection. In this study, we build 2-dimensional finite element fluid injection models that simulate thermo-poromechanical processes using a COMSOL Multiphysics®. The thermal equation (Fourier’s Law) is coupled with the poroelastic theory to investigate the role of thermohydraulic-convection and -stress in a porous medium. We confirm that these injection conditions may change pore pressure, subsurface stress, and surface displacement, which supports the necessity of monitoring during/after fluid injection.
Downscaling Precipitation Extremes Using Physics-coupled Dynamic Data Driven Adversarial Learning
Authors: Saha Anamitra , Ravela Sai
Published: February 2023

The intensity and frequency of extreme rainfall events are likely to increase under projected climate change scenarios. Given the adverse socio-economic impacts of these extreme events, we need to model their risk to develop effective policies for adaptation and mitigation. Simulating local hydrometeorological processes at the resolutions essential for assessing impacts and planning is computationally expensive using global climate models. Thus, there is a demand for efficacious downscaling from the coarse-resolution climate model outputs to the finer local scales of interest. Here, we develop a dynamic data-driven model coupled with physics, to downscale coarse-resolution climate model outputs (0.25° × 0.25°) to high-resolution (0.01° × 0.01°) rainfall. The downscaled rainfall is initially estimated by actively searching data on a manifold to learn the downscaling function incrementally using an iterative Gaussian process (GP). Upon convergence, the “first-guess” downscaled rainfall field, along with a physics-based estimation of orographic rainfall are processed by an adversarial learning framework (GAN) to refine finer-scale details. A stochastic sampling model and optimal estimation are used to correct the biases and obtain the final rainfall super-resolution fields. We assess the skill of the proposed model, using ERA5 reanalysis data and Daymet observation data at different terrain conditions (plain and hilly), and show that the downscaled rainfall closely matches the ground truth spatial patterns and extreme rainfall risk. By comparing the performance of individual components of our model (GAN, GP, and Physics) we find that the combined model outperform the individual components, and the GAN accounts for the maximum performance gain of the downscaling model.
Scenario Seismic Risk assessment of 1934 Bihar-Nepal Earthquake
Authors: lawmawma CLal , Sharma Mukat Lal
Published: February 2023

This paper presents seismic risk assessment of Bihar considering a hypothetical earthquake event similar to 1934 Bihar-Nepal earthquake. Assessment of risk has been carried out for all districts of Bihar and risk is presented in terms of economic loss. The loss estimation is performed through the combination of seismic hazard, structural vulnerability, and exposure data. Regarding the seismic input, a non-linear probabilistic approach is used to estimate the hypocenters of 1934 Bihar-Nepal earthquake and other source parameters are taken from literature. Abrahamson and Silva (2014) ground motion prediction equation is used to generate the strong ground motion at the surface level. Building exposure data are based on national census survey of India 2011. The census data provides common building typologies for each district and their relative distribution. On the basis of wall material used for construction all the buildings are grouped into four class, and seismic vulnerability functions (Martin and Silva,2011) are assigned to each building class. For each districts, total number of buildings are aggregated at the location of the maximum ground motion.  The area per building class has been assumed and reconstruction costs per square metre for each districts have been assigned based on local expert input and values identified in the literature. Finally, the district level distribution of economic loss for this earthquake scenario is obtained using the OpenQuake-engine. From this study, the expected economic loss is highest in Madhubani district followed by Muzzafarpur, Dharbanga and Sitamarhi district. Un-reinforced masonry buildings type construction, most prevalent in the rural region would experience maximum loss. A repeat of 1934 Bihar-Nepal earthquake in present day would have devastating consequences, although this scenario addresses a hypothetical event, the seismic risk assessment constitute important tools for framing public policies toward land-use planning, building regulations, insurance, emergency preparedness and could eventually minimizes economic disruption caused by earthquake.
Satellite-based evaluation of cloud cover through three generations of global atmosphere models
Authors: Medeiros Brian
Published: February 2023

Cloud cover products from multiple satellite projects are long enough to provide a robust evaluation of climate models. Using global atmosphere models forced by observed sea-surface temperature and employing satellite simulator software, three generations of the Community Atmosphere Model are evaluated. This inter-generational comparison shows how the cloud radiative effect has improved through time but cloud cover has shown only modest improvements over the past decade. Diagnostics are introduced that allow a decomposition of spatial biases to separately evaluate systematic errors in the mean from the spatial variability. Errors in cloud properties are evaluated using a dynamical regimes analysis to connect the climatological errors to the large-scale circulation. Two closely related, current-generation models, CESM2 and E3SM, are compared to show how slightly different model development and tuning decisions can impact the the cloud climatology. Leveraging multiple long-term satellite data sets suggest that despite improvements through time, there remain significant systematic errors in cloud cover. It is suggested that simultaneously constraining cloud radiative effect and cloud cover, and therefore reducing the longstanding "too few, too bright" bias, is feasible and could improve climate projections. 
Parameterizing the Large Scale Impact of Land Surface Heterogeneity Induced Circulations on Convective Cloud Development
Authors: Waterman Tyler , Bragg Andrew , Hay-Chapman Finley , Dirmeyer Paul , Fowler Meg , Chaney Nathaniel
Published: February 2023

Understanding the role of surface heterogeneity of surface fluxes in the development of convection is a critical topic in land-atmosphere interactions. This is especially relevant in the context of Earth System Models (ESMs), where simulated sub-grid surface heterogeneity over the land surface is mostly ignored by the overlying modeled atmosphere. Indeed, previous studies using Large Eddy Simulation (LES) have shown that heterogeneities in the surface field below ESM spatial resolution (~100 km) can cause appreciable secondary circulations and, at times, a significant increase in convective cloud development. These large scale changes initiated by small scale heterogeneity have yet to be adequately parameterized in ESMs. To address this particular weakness, this presentation presents a parameterization scheme for a near surface density driven circulation between two lower atmosphere columns with variable surface heating for use within ESMs.The secondary circulation parameterization is fit to data from 184 LES runs over 92 days, one run each day with a homogeneous surface and one run each day with a heterogeneous surface derived from land surface model output, over a 100 km square domain centered around the ARM site in the US Southern Great Plains (SGP) in Oklahoma. It is then tested over those 92 simulation days at the SGP site, as well as shallow convective days over four heterogeneous sites where differential heating is common: Wisconsin (lake-land), Florida (ocean-land), Missouri (urban-rural) and Appalachia (elevation). To test the circulation scheme, we use standalone columns of Cloud Layers Unified by Binormals (CLUBB) a boundary layer, cloud and shallow convection scheme used in multiple modern ESMs. CLUBB is run for three cases on each simulation day at each site: 1) as a single homogeneous column model over the domain, 2) as two separate columns over high and low sensible heat portions of the domain, and 3) following 2) with the addition of the circulation parameterization scheme. The homogeneous CLUBB simulations and those with secondary circulations are compared to evaluate the impact of the secondary circulation on cloud development, turbulent kinetic energy, and profiles of the means and variances of heat and moisture. Results over the SGP site show that the parameterized circulation yields similar changes in cloud development and profiles of heat and moisture to LES.
Hydrogels that Co-Encapsulate Slow Release Compounds and Rhodococcus rhodochrous ATCC 21198 for the Aerobic Cometabolic Treatment of 1,4-Dioxane and CAHs
Authors: Semprini Lewis , Azizian Mohammad , Wortkoetter Jacob , Rasmussen Michell
Published: February 2023

A novel aerobic process has been developed for the passive cometabolic treatment of contaminant mixtures in groundwater.  Our studies have focused on Rhodococcus rhodochrous ATCC 21198 that can concurrently oxidize 1,4-dioxane (1,4-D) and diverse mixtures of chlorinated aliphatic hydrocarbons (CAHs). We found that the short chain alkane monoxygenase (SCAM) responsible for the cometabolism of the contaminants is induced after grown on 1-butanol and 2-butanol, permitting the use of Slow Release Compounds (SRCs) that slowly hydrolyze to produce these alcohols.  Methods were developed to co-encapsulate the SRCs and ATCC 21198 in gellan-gum hydrogel beads. ATCC 21198 grows within the gellan-gum beads and upon diffusion into the beads the contaminants are transformed. In batch reactors containing the gellan-gum beads successive additions of a mixture of  1,1,1-trichloroethane (1,1,1-TCA_, cis-dichloroethene (cis-DCE), and 1,4-D were transformed for over 300 days, with the rates of cometabolism correlated with the rates of alcohol release, oxygen consumption and CO2 production. Continuous flow tests have been performed with columns packed with the gellan-gum beads. The columns mimic passive treatment that might be achieved using an in-situ permeable reactive barrier (PBR) constructed with the gellan-gum beads.  Over 99% removal of a mixture of 1,1,1-TCA, cis-DCE, and 1,4-D, each at influent concentration of 250 µg/L, was achieved with a hydraulic residence time of approximately 12 hours  The columns effectively transformed the contaminant mixture for over 600 pore volumes (300 days). The columns performance was negatively affected when cis-DCE was replaced by 1,1-dichloroethene (1,1-DCE), due to 1,1-DCE transformation product toxicity.  The column containing the SRC that produced 2-butanol was more negatively impacted by 1,1-DCE due to the lower biomass that developed in the gellan-gum beads. Studies are currently being performed in a 3-D physical aquifer model using a funnel-and-gate system with the co-encapsulated gellan-gum beads used to create a cometabolic permeable reactive barrier. 
Variations of summer extreme high temperatures in northern Eurasia during the recent decades
Authors: Fan Yi
Published: February 2023

The summer extreme high temperature days (EHTDs) in the Northern Hemisphere have been frequently detected, posing a serious threat to the safety of human life, agricultural production, and the ecological environment of many countries. This study investigates the decadal variation of summer EHTDs in northern Eurasia (30°–70°N, 10°–130°E) during 1960–2018, using the EHTD index provided by Hadley Center and the atmospheric circulation and sea surface temperature (SST) data provided by NOAA. Statistical analysis shows that the first principal component of the EHTD index fluctuates slightly over a relatively low level during 1960–1994, while it increases significantly during 1995–2018. Moreover, Z-test and sliding t-test confirm that the decadal variations of the EHTD index in terms of trends and the climatological mean values change significantly around 1994/1995. Therefore, the total period is divided into two phases, i.e., fewer EHTDs and an insignificant trend during the period from 1960 to 1994, and more EHTDs with a significant increasing trend during the late period from 1995 to 2018. During 1960–1994 (1995–2018), low pressure and cyclonic (high pressure and anticyclonic) anomalies controlled Lake Baikal and the Caspian Sea, favoring more (less) cloud cover and precipitation, absent (sufficient) solar radiation and increased (decreased) EHTDs over there. Global warming and internal variability of the North Atlantic are both responsible for the decadal variations of EHTDs. On one hand, regression analysis shows that the global warming trend shows a significant influence on the positive pressure anomalies over the areas to the south of Lake Baikal. On the other hand, during 1995–2018, the anomalous Rossby wave activities induced by warmer than normal North Atlantic leads to high-pressure anomalies over the Caspian Sea, resulting in the significant anticyclonic anomaly over the area, which favors the more frequent occurrence of EHTDs than those during 1960–1994. Meanwhile, the Atlantic jet is located northward. The area around the Caspian Sea is to the right side of the jet stream exit. Under such a background, the negative vorticity advection at the upper-level troposphere would lead to the divergence anomaly and strengthen the sinking motion between lower- and higher- levels. Thus, the summer EHTD tends to be maintained over the Caspian Sea.
A Deep Learning-based Toolbox for Automated Monitoring of Central Asian Glacial Lakes from Space
Authors: Tom Manu , Frey Holger , Allen Simon , Cicoira Alessandro , Niggli Laura , Huggel Christian
Published: February 2023

In recent decades, climate change has intensified the melting of glaciers in high mountain regions around the world, leading to the formation of new glacial lakes. These lakes can cause damage up to several hundred kilometres downstream when an outburst flood occurs. While more and more glacier lake inventories are becoming available to the research community, high-frequency mapping and monitoring of these lakes are still essential to assess hazards and estimate Glacial Lake Outburst Flood (GLOF) risks, particularly for lakes with high seasonal variations. In Central Asia, new lakes have been known to develop quickly, and non-stationary lakes can expand or regrow within a matter of weeks to months. Monitoring these lakes is crucial to understanding and mitigating the risks they pose.Detecting glacial lakes using satellite sensors is difficult due to their small size and the fact that they are often frozen for much of the year. Furthermore, optical satellite imagery can be hindered by clouds. Additionally, cast and cloud shadows, as well as increasing lake and atmospheric turbidity, make it challenging to accurately observe and monitor these lakes using optical satellite imagery. On the other hand, using a SAR satellite sensor to monitor these lakes is difficult during windy scenarios and changes in backscattering due to variations in turbidity and the presence of cast shadows.We have developed a Python-based toolbox for mapping potentially dangerous glacial lakes in Central Asia and for monitoring the dynamics of these lakes over time and space. The proposed analytical toolbox uses a combination of Sentinel-1 Synthetic Aperture Radar (SAR) and Sentinel-2 optical satellite data as input. Satellite data fusion allows high temporal resolution, while SAR can penetrate cloud cover and allow year-round monitoring. The user interface for the toolbox is designed to also accommodate users with a non-programming background.The Convolutional Neural Network (CNN)-based approach fuses information from heterogeneous satellite input data by learning joint satellite embeddings (feature representations), that are equivariant to the type of satellite input data. The proposed network has separate encoder branches for each input sensor. The learned embeddings are then fused to guide the identification of glacial lakes. The ultimate goal of our data-driven methodology is to create geolocated maps of the target regions by classifying each pixel as either a lake or background in a supervised manner.This work is part of the GLOFCA project which aims to lower the vulnerability of people in Kazakhstan, Kyrgyzstan, Tajikistan, and Uzbekistan to GLOFs. This project is implemented by UNESCO and funded by the UN Adaptation Fund, in collaboration with various international and national partners.
Multi-Proxy Study of Chicxulub Impact Breccias and Paleogene Carbonates in the Santa Elena Borehole, Yucatan, Mexico
Authors: Urrutia-Fucugauchi Jaime , Perez-Cruz Ligia , Ortega-Nieto Alejandro , Escobar-Sanchez Elia , Venegas-Ferrer Rafael
Published: February 2023

Results of a joint paleomagnetic, petrographic, X-ray fluorescence, and stable isotope study of the impact breccias and Paleogene carbonate sediments in the Santa Elena borehole are used to investigate the impact effects and climatic and environmental changes in the Chicxulub crater and Yucatan platform, southern Gulf of Mexico. The Santa Elena borehole reached a depth of 504 m and was continuously cored, sampling the post-impact carbonate sediments and impact breccias. We analyze the section from ~230 m to ~340 m, corresponding to the upper breccias and Paleogene sediments, spanning the breccia-carbonate contact at 332 m depth. The lithological column from macroscopic and thin-section petrographic analyses comprises limestones, dolomitized limestones with thin clay layers, and breccias rich in melt and basement clasts within a melt- or carbonate-rich matrix. Magnetic polarities define a sequence of reverse to normal intervals within chrons 29r to 26r in the impact breccias and basal carbonates. Magnetic susceptibility shows high variable values in the breccias correlating with the clast contents and carbonate or melt-rich matrix. Low paramagnetic or diamagnetic susceptibilities characterize the carbonate sequence. Fe-Ti oxides are dominant magnetic carriers with pseudo-single and multidomain states. In the upper breccias, more complex magnetic mineralogy is observed, with hydrothermal alteration phases. The ∂13C values in the first 20 m interval range from 1.2 to 3.5 ‰ and ∂18O values range from -1.4 to -4.8 ‰. Isotopes show variation trends that correlate with the marine carbon and oxygen isotope patterns for the K-Pg boundary and early Paleocene records. Positive carbon isotopes suggest high productivity, with apparent recovery following the K-Pg extinction. Oxygen isotope values are negative, reflecting regional and local effects. Geochemical data define characteristic trends, with silica decreasing gradually from high values in the breccias, low contents between 320 to 247 m, with intervals of higher variability, particularly between 280 and 247 m, and then increased contents at 247-230 m. Ca shows the opposite trend with low values in the breccias, high in the Paleocene carbonates, and low in the PETM. Major oxides and trace elements show similar patterns, e.g., Fe, Ti, K, and Al, recording changing climatic and depositional conditions in the platform. Results are interpreted in terms of the paleoclimatic and paleoenvironmental evolution of the southern Gulf of Mexico at the Cretaceous-Paleogene boundary, Paleocene and Eocene, including analysis of post-impact processes, hydrothermal activity, platform sedimentation, and sea level changes. 
Leveraging Hydroclimate and Earth Observation to Predict Grain Production in Sub-Saharan Africa
Authors: Lee Donghoon , Davenport Frank , Shukla Shraddhanand , Harrison Laura , Husak Greg , Funk Chris , Budde Michael , Rowland James , McNally Amy , Verdin James
Published: February 2023

The importance of forecasting agricultural production in Sub-Saharan Africa (SSA) is increasing for the management of agricultural supply chains, market forecasting, and targeting of food aid. In particular, agricultural forecasts enable governments and humanitarian organizations to respond more effectively to shocks in food production and price spikes resulting from extreme droughts. In this study, we use hydroclimate, earth observations (EO) and machine learning to develop an operational, sub-national grain production forecast system for a number of SSA countries, including food-insecure regions where rapid response is critical. Before creating the forecast, we collect and organize crop production data from the Famine Early Warning Systems Network in order to identify trends and variability in agricultural technology, climate, and vegetation. In addition, we demonstrate the capability of hydroclimate and EO data to capture favorable or unfavorable crop development conditions during the growing season. In addition, we demonstrate a unique capability that explains how EO characteristics influence current grain production forecasts, thereby enhancing the forecasts' reliability and efficacy. This research lays the groundwork for the development of a large-scale, operational crop yield forecasting system that will provide actionable predictions of food shocks for famine early warning and guide advanced preparedness and response strategies.
Continuous water vapor isotope measurements at the Amazon Tall Tower Observatory site during a dry season: Insights into diel atmospheric moisture sources
Authors: Komiya Shujiro , Jones Sam , van Asperen Hella , Lavric Jost , Adnew Getachew , Moonen Robbert , Botia Santiago , Quaresma Dias-Júnior Cléo , Acosta Gotuzzo Ricardo , Rodrigues Ferreira Rosaria , Kondo Fumiyoshi , Trumbore Susan
Published: February 2023

The recent development and improvement of commercially available laser-based spectrometers have expanded onsite continuous water vapor (H2O) stable isotope composition (e.g. δ18O, δ17O and δ2H) measurements in a variety of sites across the world in the last decade. However, we still lack continuous observations in the Amazon basin region, a region that significantly influences atmospheric and hydrological cycles on local to global scales.The Amazon Tall Tower Observatory (ATTO) site is located in well-preserved central Amazon upland rainforest. In August 2022, a commercial cavity-ring down (CRDS) analyzer (L2140-i model, Picarro, Inc., USA) was installed to continuously measure water vapor isotope compositions at four levels (79, 38, 24, and 4 m above ground) of the 80 m walk-up tower. Also, deuterium excess (hereinafter called d-excess; d-excess = δ2H–8δ18O) was assessed to trace processes that contribute to diel variation in atmospheric moisture inside and above canopy.During the dry season, d-excess generally decreased during the nighttime, reaching minimum values at 6 am to 8 am local time (LT), followed by an increase to maximum values at 12 pm to 4 pm. The diel d-excess variation indicates that atmospheric entrainment occurred in the early morning and evapotranspiration was a dominant moisture source in the afternoon. Further results will be analyzed and discussed in the presentation.  
Strontium partitioning in calcite and its controling factors
Authors: Zhang Shuo , DePaolo Donald , Jia Qicui
Published: February 2023

Strontium (Sr) is a common trace element in calcite which is incorporated during calcite precipitation through either inorganic or organic pathways. The ratio of Sr to calcium (Ca) in carbonate rocks and minerals has been widely used in studies of paleoceanography, marine sediment diagenesis, and hydrothermal alteration of oceanic crust. The partitioning coefficient of Sr (KSr) describes fundamentally the partitioning of Sr between calcite and aqueous solutions, but is a complicated function of environmental conditions and water composition. It has long been recognized that KSr is strongly dependent on the precipitation rate of calcite (Rp), which has been formulated in a surface kinetic model [1] and a subsequent ion-by-ion model [2]. We re-evaluate available experimental data of Sr partitioning in calcite and find apparent dependence of KSr on calcite oversaturation and solution pH [3]. An ion-by-ion model is developed that successfully reproduces the observed KSr values at given solution chemistry [4]. Our model also reproduces observed KSr-Rp relationships at various temperatures of 5, 25 and 40 oC. This model provides an opportunity to evaluate effects of past seawater composition on Sr partitioning and their possible roles in reconstructing seawater Sr/Ca ratio in the geological history [5], in using pore fluid Sr concentration to extract sediment-fluid exchange rates in deep sea carbonate sediments [5], and in understanding Sr partitioning in biogenic calcite such as foraminifera.Reference[1] DePaolo, D.J., Surface kinetic model for isotopic and trace element fractionation during precipitation of calcite from aqueous solutions. Geochimica et Cosmochimica Acta, 2011. 75(4): p. 1039-1056.[2] Nielsen, L.C., J.J. De Yoreo, and D.J. DePaolo, General model for calcite growth kinetics in the presence of impurity ions. Geochimica et Cosmochimica Acta, 2013. 115: p. 100-114.[3] Zhang, S. and D.J. DePaolo, Equilibrium calcite-fluid Sr/Ca partition coefficient from marine sediment and pore fluids. Geochimica Et Cosmochimica Acta, 2020. 289: p. 33-46.[4] Jia, Q., et al., A model for pH dependent strontium partitioning during calcite precipitation from aqueous solutions. Chemical Geology, 2022. 608: p. 121042.[5] Zhang, S., R.J. Zhou, and D.J. DePaolo, The seawater Sr/Ca ratio in the past 50 Myr from bulk carbonate sediments corrected for diagenesis. Earth and Planetary Science Letters, 2020. 530: p. 115949.
The thermodynamics of aggregate development, structure, and size
Authors: Ritschel Thomas , Totsche Kai
Published: February 2023

Soil's aggregated structure is fundamental for the functioning of soil, and aggregation is a crucial process within pedogenesis. While aggregates are often considered stable entities, bonds between aggregate forming materials can form, consolidate, and break over time. Consequently, individual aggregates are subject to permanent restructuring and do not show a final spatial configuration that remains stable. Instead, only the temporal average of aggregate features converges to a constant value and –in case the system comprises a large ensemble of aggregates– a situation of thermodynamic equilibrium will establish over time. The dynamics of disaggregation and restructuring might be equally important for the establishment of aggregate structure as the aggregation mechanisms themselves and should therefore be considered when modeling structure formation. We conducted a comprehensive numerical analysis to reveal the interplay of aggregation mechanisms and the breaking of aggregate bonds in a physicochemical framework that combines three-dimensional transport with DLVO-type surface interactions. The attractive and repulsive energies between aggregate forming materials were used to model the temporal dynamics and stability of bonds in a heuristic manner. Despite the ongoing formation and breaking of bonds, we show that aggregation approaches a thermodynamic equilibrium depending on the physicochemical environment. Specifically, an ensemble of aggregates of sufficient size to provide robust statistical averages converges to a state of constant mean properties, e.g., aggregate size and aggregate morphology. Aggregates and their structure should therefore be considered dynamic entities, where an ensemble might reach a steady-state equilibrium, but each individual aggregate does not.
Exploring biosignatures and geomorphology of Mars with close-up images – preparatory activities for the ExoMars mission.
Authors: Kuhn Nikolaus J. , Ligeza Gabriela , Bontognali Tomaso , Josset Jean-Luc , Kuhn Brigitte
Published: February 2023

ExoMars is an astrobiology program led by the European Space Agency, which aims to launch a rover to Oxia Planum to search for signs of past life. Although the primary goal of the mission is focused on astrobiology, there are several secondary mission objectives, such as investigating the geomorphology, aeolian and volcanic processes to better understand the evolution and paleoclimate of Mars. CLUPI (a close-up imager) will be used to acquire high-resolution images of rocks, geological outcrops, and drill cores to provide the overview on the geology of Oxia Planum. Due to the limited amount of data that can be transmitted at once from Mars, only few CLUPI images will be available daily to the science team for assessing hypotheses and decide how to program the rover of the next cycle of activities. Thus, it is curial that each CLUPI image will contain a maximum of relevant information. For this reason, we are conducting preparatory tests and simulations to identify ideal CLUPI working conditions in view of the prime mission on Mars. In this work, we specifically explored the impact that different illumination conditions (i.e., direction of the illumination axis and intensity of direct light vs diffused light) may have on the detection of textures and sedimentary structures in close-up images. We showed that by acquiring images at different type of day, under specific lighting conditions, it is possible to enhance the probability of detecting various rock textures and geological samples, which can contribute to the diverse data collection and answer main question about the geomorphology of Oxia Planum.
The yielding process of the natural mud under current and wave shear stress
Authors: Xia Yuezhang , Wang Shaohua , He Zhiguo , Gu Hengye
Published: February 2023

The rheological properties of natural mud are closely related to nautical depth estimation, wave propagation, and morphology evolution of muddy coast. In this study, the rheological properties of the natural mud collected from Luxi Island and Zhoushan Island in China were investigated. Shear stresses in steady state or oscillatory state were imposed on mud samples directly to obtain the yielding process under tidal currents or waves. The results showed that both apparent viscosity and complex viscosity experienced two sharp declines with increasing shear stress, indicating a two-step yielding nature of natural mud. Two yield stresses, namely, static yield stress and fluidic yield stress correspond to the yielding processes of elasticity and viscosity breakdown, respectively. The static yield stress in the oscillatory shear stress tests was lower than that in the steady shear stress tests, and the fluidic yield stress of natural mud in oscillatory shear stress tests was higher than that in the steady shear stress tests. The above phenomenon was explained by the viscoelastic-oscillation theory. Furthermore, the experimental results indicated that the initial storage modulus had a closer connection to both yield stresses in comparison with mud density. This study not only provided a guideline for having a better understanding of the two-step yielding process of natural mud, but will also provide scientific support for the assessment of fluid-mud formation, sediment transport and morphology evolution, the interaction between waves or tidal currents and muddy seabed, and protection of seafloor infrastructures.
Nighttime Urban Heat Island with rainfall impact during monsoon season in South Korea
Authors: Lee Jeongseop , Ko Dongwon , Kim Sanghyun
Published: February 2023

Climate change frequently generated extreme meteorologic event. The temperature difference between urban and its adjacent rural area had been defined as Urban Heat Island(UHI). The UHI during nighttime associated with high humidity condition introduces inconvenient living condition during Monsoon season. The generation of rainfall event and intensity of UHI had been known to counter reciprocal due to the apparent rainfall disturbance to vertical temperature profile. The hydro-meteorological data collected during summer season between 2013 and 2022 was used to evaluate the UHI intensity in Busan, South Korea. The impact of rainfall generation pattern was analyzed to configure the relationship rainfall and nighttime UHI. The results were derived that the temperature difference showed the characteristics of each year rather than the regular form.
Frontal collapse of San Quintín glacier (Northern Patagonia Icefield), the last piedmont glacier lobe in the Andes
Authors: Pętlicki Michał , Rivera Andrés , Oberreuter Johnatan , Uribe José Andrés , Reinthaler Johannes , Bown Francisca
Published: February 2023

Glacier fronts are retreating across the globe in response to climate warming, revealing valleys, fiords, and proglacial lakes. The piedmont lobe of San Quintín, the largest glacier of the Northern Patagonia Icefield, in southern Chile, has recently entered a catastrophic phase of frontal retreat, where its terminus is rapidly disintegrating into large tabular icebergs calving into a new proglacial lake. We present results of a unique airborne GPR survey of the terminus of this large Patagonian glacier (763 km2 in 2017), complemented with an analysis of ice flow velocity, satellite imagery, and ice elevation change to show that the ongoing retreat is caused by recent detachment of a floating terminus from the glacier bed and may shortly lead to the disappearance of the last existing piedmont lobe in Patagonia. Finally, we discuss how the observations of San Quintín’s ongoing collapse may give insights into processes governing frontal retreat of fast-flowing temperate glaciers and the quasi-stability of the floating termini.
Evaluation of the performance of regional transport models in simulating CO2 variability over India employing WRF-STILT modelling framework
Authors: Thilakan Vishnu , Pillai Dhanyalekshmi , S Kumar Jithin
Published: February 2023

India needs a high-resolution estimation of carbon sources and sinks to implement the country’s climate change action plans and mitigation strategy effectively. Current carbon estimates over the Indian region based on the “Bottom-up” approach suffer from significant uncertainty, which calls for more process-based models and atmospheric inverse modelling to obtain a more accurate budget. Inverse models constrain the carbon fluxes based on atmospheric observation of CO2 mole fractions. The unavailability of amble observations over the Indian domain critically impacts estimation accuracy. Fortunately, there are increasing efforts to improve the availability of CO2 observation over the domain. Along with the observations, the availability of a suitable transport model to simulate the CO2 distribution is essential to the accurate inverse estimation of carbon fluxes. The inability of coarse-resolution global models to simulate the fine-scale variability in CO2 distribution warrants developing a regional high-resolution modelling system. Here we evaluate the performance of a regional high-resolution modelling system which utilises meteorological fields from the Weather Research and Forecasting (WRF) model to simulate the CO2 transport over the Indian domain using a lagrangian particle dispersion model, Stochastic Time-Inverted Lagrangian Transport Model (STILT). Using lagrangian models enables us to study the CO2 distribution at very high resolution (even at sub-grid scale) with reduced cost. We use the vegetation photosynthesis and Respiration Model (VPRM), coupled with the modelling system, to simulate the biospheric fluxes. The anthropogenic and biomass burning fluxes are obtained from different available inventories. We use CO2 in-situ observations from different parts of the Indian domain, which utilises flask measurements and PICARRO CRDS instruments, to evaluate the modelling system. Our high-resolution modelling framework shows good skill in simulating the CO2 variability over the region. The results of the evaluation will be discussed in detail during the presentation.
NDVI and Accumulated Antecedent Precipitation (APP) in four different vegetation types in drylands of Mendoza, Argentina
Authors: Brieva Carlos , Saco Patricia , Sandi Steven , Rodriguez Jose
Published: February 2023

Arid and semi-arid ecosystems are under the pressure of climate change and are facing overgrazing and logging, which has led to increased degradation and desertification processes. The Drylands of Mendoza, Argentina, are fragile ecosystems devoted to cattle breeding on native bushes and rangelands. Livestock farming relies on the productivity of natural resources, closely related to the monthly, annual, and seasonal rainfall, which is a critical driver of vegetation productivity and dynamics. This study aims to determine the relationship between NDVI and Accumulated Antecedent Precipitation (AAP) in natural dryland as a basis for decision support in cattle grazing. NDVI from MODIS-Terra (MOD13Q1 V6.1) and AAP estimated by satellite using GPM (Global Precipitation Measurement) were correlated using Pearson's Correlation Coefficient at monthly timesteps over a period of 20 years (June 2000 to May 2020) considering 0 APP (monthly) and 1, 3-, 6-, 9- and 12-months AAP. The analysis was carried out spatially (pixel-to-pixel) in 5 points of each of 4 primary vegetation types of the interest area (Bush steppe with low land cover; Open Bush; Forest of Prosopis Flexuosa; and Psammophilious Grassland). NDVI responses to 3 months of AAP were significant for all vegetation types in the study area. Tracking vegetation responses to rainfall in this region is of outmost importance for management of the limited water resources.