bluuebunny/crossref_metadata_2025 huggingface dataset:
Strong variability in the thermal structure of Tibetan Lithosphere
Authors: Xia Bing , Artemieva Irina , Thybo Hans , Klemperer Simon
Published: February 2023

We present a model of thermal lithospheric thickness (the depth where the geotherm reaches a temperature of 1300°C) and surface heat flow in Tibet and adjacent regions based on the new thermal-isostasy method. The method accounts for crustal density heterogeneity, is free from any assumption of a steady-state lithosphere thermal regime, and assumes that deviations from crustal Airy-type isostasy are caused by lithosphere thermal heterogeneity. We observe a highly variable lithospheric thermal structure which we interpret as representing longitudinal variations in the northern extent of the subducting Indian plate, southward subduction of the Asian plate beneath central Tibet, and possible preservation of fragmented Tethyan paleo-slabs. Cratonic-type cold and thick lithosphere (200-240 km) with a predicted surface heat flow of 40-50 mW/m2 typifies the Tarim Craton, the northwest Yangtze Craton, and most of the Lhasa Block that is likely refrigerated by underthrusting Indian lithosphere. We identify a ‘North Tibet anomaly’ with thin (<80 km) lithosphere and high surface heat flow (>80-100 mW/m2). We interpret this anomaly as the result of removal of lithospheric mantle and asthenospheric upwelling at the junction of the Indian and Asian slabs with opposite subduction polarities. Other parts of Tibet typically have intermediate lithosphere thickness of 120-160 km and a surface heat flow of 45-60 mW/m2, with patchy anomalies in eastern Tibet. While different uplift mechanisms for Tibet predict different lithospheric thermal regimes, our results in terms of a highly variable thermal structure beneath Tibet suggest that topographic uplift is caused by an interplay of several mechanisms.
Interannual variability and seasonality of carbonyl sulfide fluxes of an Austrian Scots pine forest
Authors: Spielmann Felix M. , Hammerle Albin , Scholz Katharina , Wohlfahrt Georg
Published: February 2023

The gross primary productivity (GPP), that is the gross uptake of carbon dioxide (CO2) by plants, cannot be measured on ecosystem level but must be inferred by either applying models or measuring proxies. One of those proxies is the trace gas carbonyl sulfide (COS), which is of particular interest, because it shares a very similar pathway into plant leaves as CO2 and is, contrary to the latter, generally not re-emitted.Due to the need of expensive and sensitive instrumentation, e.g., quantum cascade lasers, only a limited amount of ecosystem measurements and even fewer long-term studies at this scale have been conducted. Consequently, more data focusing on the seasonality and the interannual variability of COS ecosystem fluxes are needed to understand the relationship of the COS to CO2 uptake, i.e., the leaf relative uptake (LRU), for reliable GPP calculations.To investigate the impact of environmental changes on the LRU we conducted COS, CO2 and H2O eddy covariance flux (EC) measurements at our newly established forest field site in Mieming (Austria) for the last two years. The field site's dominating tree species is Scots pine (Pinus sylvestris) with Juniper trees (Juniper communis) in the understory. In addition to the EC measurements, we conducted branch chamber measurements within the crown of the Scots pine, two at the treetop and one within the canopy.Our EC measurements indicate a strong interannual variability of the COS fluxes. While we observed the highest COS uptake in 2021 during May, the COS uptake in 2022 was higher in the period from June to August. We also observed this pattern for the net CO2 fluxes. The fluxes of COS and CO2 concurrently decreased during the winter month and the forest turned into a net source for CO2, while COS was taken up continuously.The mean LRU across all branch chamber measurements was 1.67 (-) with the chambers within the canopy generally having lower LRUs (1.39 (-)).
The inclusion of intraurban inequalities in urban growth models
Authors: Bastos Moroz Cassiano , Sieg Tobias , Thieken Annegret
Published: February 2023

The last IPCC report highlighted that the urban expansion to areas exposed to climate-driven natural hazards might significantly increase disaster risk in the near future. Understanding risk as the combination of hazard, exposure and vulnerability, these increased trends will be more expressive among the economically and socially marginalized urban residents, particularly in informal settlements. A major cause of this process is spatial intraurban inequalities. The urban poor are not only more vulnerable to natural hazards, e.g., due to a lack of resources; they are also often driven towards the less valuable areas, including hazardous locations such as flood plains and steeper hillslopes, which likely increase their exposure. However, disaster risk research still lacks more holistic tools to simulate and better understand the interrelations among urban expansion, intraurban inequalities, and exposure to natural hazards. We aim to develop an urban growth model that incorporates different socioeconomic groups to investigate the impact of these inequalities on their hazard exposure. We developed our model following the multilevel modeling framework for urban growth. First, a demand module quantifies the amount of urban growth that is expected for each socioeconomic group. Then, a spatial allocation module determines where this growth will take place to fulfill these demands. In the allocation, the most probable locations of future urban areas are individually determined for each group as a function of driving forces. These include biophysical and socioeconomic factors such as terrain slope, elevation, and distance to infrastructure. We applied the model in the municipality of Rio de Janeiro, Brazil, while accounting for three different income groups. Preliminary results indicate that the characteristics of new urban areas change significantly as a function of the income class, with a strong pattern of spatial segregation. Low-income households were found to have a higher probability of being located on steeper terrain than middle- and high-income households. In addition, new low-income urban areas were also found to be more distant from the city center, the coastline, and the main city infrastructure including subway and train stations. These results demonstrate the relevance of incorporating existing inequalities into urban growth models, especially in developing spatial planning policies in accordance with existing risks to natural hazards.
Controls on Sediment Delivery to New England Salt Marshes and Resulting Limits on Future Resilience
Authors: Woodruff Jonathan , Autery Molly , Baranes Hannah , Cook Timothy , Griswold Frances , Hansen Lucy , Yellen Brian
Published: February 2023

Inorganic sediment supply is a critical component of a salt marsh’s ability to vertically aggrade in response to relative sea level rise, yet there remains significant uncertainty on the primary sources, timing, and rates of sediment delivery to marshes. This is particularly true for the Northeastern, U.S. Atlantic coastline where the magnitude and sourcing of sediment varies widely due to post-glaciated landscapes. Here we present results from a 3-year study between 2020 and 2023 designed to inform management and restoration decisions related to northeast marshes through the development of a scalable method for assessing the availability and distribution of inorganic sediment to and within marshes, including the identification of thresholds of inorganic sediment delivery required to maintain a stable marsh platform under various rates of sea level rise for the region. Field investigations involved instrumental observations, deployment and recovery of seasonal sediment traps, and the collection and analysis of marsh core samples. The study targets 12 marsh systems spanning environmental gradients for the region that allowed us to examine different sources and delivery mechanisms of sediment. Our compilation of existing data reveals spatial variability in marsh accretion rates, but also highlights regional trends and the general agreement among rates determined through a variety of different methodologies and time spans. Our instrumental observations and sediment trap deployments confirm differences in sediment delivery among marshes. Back barrier marshes with relatively small watersheds predominantly accumulated inorganic sediment during the fall in response to large storms and wave activity suspending coastal and offshore sediment deposits (marine sources) that are carried into marshes through tidal advection. In contrast, marshes proximal to large rivers (>10,000 km2 watersheds) have higher accumulation rates and receive the bulk of their inorganic sediment in response to fluvial delivery of terrestrial sediment during spring freshet events. Among our 12 study marshes, only one experienced its highest rate of sediment accumulation during summer months, which we attribute to substantially greater crab herbivory promoting internal recycling of sediment. Overall, we have measured sediment accumulation in over 450 individual traps across spring, summer and fall seasons in twelve marshes. The results from the analysis of these samples represents the largest dataset of its kind for the region and enable defining regionally appropriate input variables for modeling the spatial variations of sedimentation across marsh surfaces as a function of tidal inundation and distance to the nearest channel, as well as providing defined sedimentation limits needed to sustain healthy marsh growth under future sea level rise and various potential restoration pathways.
Optical and radar remote sensing improve DEM-based geomorphic change detection in semi-arid landscapes
Authors: Walker Simon , Wilkinson Scott , Bartley Rebecca , Levick Shaun , Kinsey-Henderson Anne , Khan Sana , Castellazzi Pascal
Published: February 2023

Accurate measurements of geomorphic change are necessary to improve quantitative and conceptual models in geomorphology. New generation high-resolution topography (HRT) is enabling increasingly accurate quantification of surface change via differencing of fine scale (<1 m) multi-temporal digital elevation models (DEMs). The resulting DEMs of difference (DoDs) provide spatially continuous estimates of surface change. However, harnessing the information contained in HRT DoDs requires progressively sophisticated methods for handling the error propagated into a DoD from each DEM. As HRT acquisition increases, and technology to host and distribute the data improves, there is increasing need for reliable and repeatable error handling procedures. We investigate the potential for satellite-borne optical and radar data to improve DEM-based geomorphic change detection in semi-arid landscapes. The primary motivation for this work is to enable improved geomorphic change detection in semi-arid landscapes affected by extensive erosion. We apply the methodology to a ~15 km2 catchment adjacent to the Great Barrier Reef, Australia, where independent end-of-catchment sediment load data is available for comparison. Our goal is to enable improved geomorphic change detection over relatively large areas (>1 km2) by minimising systematic error propagated into a DoD, particularly from DEMs with sparse ground control networks.We find the methodology reliably decreases the systematic error in our DoD and improves the separation of real geomorphic change from noise. However, the presence of grass and consequent point misclassification remains a key challenge even with a relatively high point density (~48 pts·m2) airborne-lidar dataset. This is the first time optical and radar remote sensing have been used alongside airborne-lidar for improved DEM-based geomorphic change detection in semi-arid landscapes.
Interaction between large-scale vortical structures and quasi-streamwise vortices in Langmuir turbulence
Authors: Tsai Wu-ting , Lu Guan-hung
Published: February 2023

Langmuir circulations arise through the interaction between the Lagrangian drift of the surface waves and the wind-driven shear layer. The high shear rate alone is sufficient for generating quasi-streamwise vortices within the shear layer. Despite the different formation mechanisms, both vortical structures manifest themselves by inducing wind-aligned streaks on the surface. Numerical simulations of a stress-driven turbulent shear layer bounded by monochromatic surface waves are conducted to reveal the mutual interaction between the large-scale vortical structures of Langmuir circulations and the small-scale quasi-streamwise vortices in Langmuir turbulence. The averaged structure of Langmuir circulations is educed from conditional averaging guided by the signatures of predominant surface streaks obtained from empirical mode decomposition. The width of the averaged vortex pair of Langmuir circulations is found to be comparable to the most unstable wavelength of the wave-averaged Craik–Leibovich equation. Small-scale coherent vortical structures are identified using a detection criterion based on local analysis of the velocity-gradient tensor and their topological geometry. Quasi-streamwise vortices accumulated beneath the windward surface are found to dominate the distribution of small-scale coherent vortical structures. Employing the variable-interval spatial average to the identified quasi-streamwise vortices reveals that they tend to form in the edge vicinity of the high-speed surface jets induced by the Langmuir cells. The tilting of vertical vorticity at the outer edges of surface jets by shear current and wave drift enhances the formation of quasi-streamwise vortices. The results highlight the differences in the coherent vortical structures between the Langmuir turbulence and the turbulent wall layer.
STITCHES: a comprehensive option for Earth System Model emulation for impacts research, and its implications for designing future ESM scenario experiments
Authors: Dorheim Kalyn , Snyder Abigail , Tebaldi Claudia
Published: February 2023

Emulators of Earth System Model (ESM) outputs have the potential to become a powerful tool for the impacts research community. If successful in emulating the needed variables at the required spatial and temporal resolution, they can supply impact model(er)s with the inputs necessary to explore how future water, energy, economic, and land systems evolve under a wide range of future scenarios. This complements the availability of ESM output currently limited to a small number of future scenarios - due to the computational costs of running fully coupled climate models - since emulators are by construction computationally efficient. STITCHES is an open-source climate emulator that can produce time series of multiple ESM variables, at the ESM original temporal and spatial resolution, by recombining existing model output into new scenarios on the basis of the scenario global temperature trajectory. In this talk, we will focus on how STITCHES can be used to explore new scenarios by filling in the space between existing scenarios. We will also discuss how insights from emulators such as STITCHES may be used to inform climate modeling centers on where to prioritize resources in future scenario simulations. 
Numerical Modeling of Vadose Zone Processes using Version 5 of HYDRUS and its Specialized Modules
Authors: Simunek Jiri , Brunetti Giuseppe , Jacques Diederik , Zhou Tiantian , Šejna Miroslav
Published: February 2023

In this presentation, we will review version 5 of HYDRUS, which resulted from merging earlier versions of HYDRUS-1D (4.x) and HYDRUS (2D/3D) (3.x), implementing the new integrated form of coupling PHREEQC with HYDRUS (HPx), and including new modules such as Furrow, PFAS, Particle Tracking, Dynamic Plant Uptake, Cosmic, Stable Isotopes, C-Ride, etc. The new HYDRUS GUI dramatically improves graphical capabilities and extends its compatibility to new Windows-based (e.g., 64) bit) operating systems. The new modules and capabilities include: a) the Particle Tracking module (to calculate soil water’s transit times and their frequency distributions), b) the Cosmic module (to calculate cosmic-ray neutron fluxes and to use them to inversely estimate large-scale soil hydraulic properties), c) the Dynamic Plant Uptake (DPU) module (to calculate the translocation and transformation of chemicals in the soil-plant continuum), d) the PFAS module (to consider sorption on the air-water interface and the effects of concentration on viscosity and surface tension, and correspondingly on conductivities and pressure heads), e) the Isotope module (to consider the fate and transport of soil water isotopes with evaporation fractionation, f) the C-Ride module (to consider colloid and colloid-facilitated solute transport), and many other new options and graphical (e.g., two-dimensional z-t graphs of main variables) capabilities. Several nonstandard HYDRUS modules (e.g., accounting for overland flow, freezing/thawing, and alternative root water uptake models) will also be discussed.  
Investigating the Evolution of Solar Wind Outflows by Using Radial and Non-Radial Tracking
Authors: Alzate Nathalia , Morgan Huw , Seaton Daniel , Di Matteo Simone
Published: February 2023

Understanding the source of the variability in the slow solar wind is a key part of Space Weather research because it can lead to an understanding of the physical processes that drive solar activity, heat the corona and accelerate the solar wind.  Achieving this requires establishing connections between the low corona, through the upper corona, and into the solar wind.  We have developed advanced image processing techniques able to reveal structures (on various timescales) in both EUV and visible-light data providing continuous tracking of brightness enhancements from the coronal base out to the radial extended corona.  Our work provides the capabilities to study features in the solar wind and subsequently study the evolution between EUV/WL and in situ of the plasma flows that give rise to them.  After a brief overview of our advanced image processing techniques, we discuss differences and similarities between the properties of outflows identified propagating along radial and non-radial paths (e.g. occurrence rate, formation height and velocities).  Some of these structures match previously identified solar wind periodic density structures in coronagraph observations. These results have important implications for the understanding of solar wind formation (height at which the structures form, unprecedentedly enabled by the uninterrupted field of view) and heating (velocity profiles provide information on the acceleration of these plasma parcels) thus supporting the interpretation and the understanding of the evolution of solar wind plasma.
Cascading flood hazards: the role of large wood transport
Authors: Ruiz-Villanueva Virginia
Published: February 2023

Floods are one of the most relevant natural hazards, causing significant socio-economic damage every year globally. They will likely continue to increase for various reasons: the climate and global changes, two relevant ones. More importantly, our still limited capability to predict river response to flooding and anticipate the consequences by designing proper and sustainable risk mitigation measures. A recent example was Europe's floods in July 2021, the highest recorded. They led to many casualties and economic losses (i.e., 180 fatalities and billions of Euros). Extreme long, high-intensity rainfall resulted in extreme flows, particularly in small tributaries, but this could not solely explain the devastating impacts. Geomorphological changes, bank erosion and channel widening, sediment erosion and transport, and uprooted and transported trees and instream large wood accumulated at bridges played a significant role. However, these cascade processes are rarely quantified or considered in flood hazard and risk analysis. This is the focus of this talk. Case studies showing a combination of modelling approaches will illustrate how quantifying the supply and transport of instream large wood is essential in river reaches crossing infrastructures like bridges to assess flood-related hazards and risks.
Foehn Wind Analysis using Unsupervised Deep Anomaly Detection
Authors: Milz Tobias , Hofsteenge Marte , Katurji Marwan , Vetrova Varvara
Published: February 2023

Foehn winds are accelerated, warm and dry winds that can have significant environmental impacts as they descend into the lee of a mountain range. For example, in the McMurdo Dry Valleys in Antarctica, foehn events can cause ice and glacial melt and destabilise ice shelves, which if lost, resulting in a rise in sea level. Consequently, there is a strong interest in a deeper understanding of foehn winds and their meteorological signatures. Most current automatic detection methods rely on rule-based methodologies that require static thresholds of meteorological parameters. However, the patterns of foehn winds are hard to define and differ between alpine valleys around the world. Consequently, data-driven solutions might help create more accurate detection and prediction methodologies. 
State-of-the-art machine learning approaches to this problem have shown promising results but follow a supervised learning paradigm. As such, these approaches require accurate labels, which for the most part, are being created by imprecise static rule-based algorithms. Consequently, the resulting machine-learning models are trained to recognise the same static definitions of the foehn wind signatures. 
In this paper, we introduce and compare the first unsupervised machine-learning approaches for detecting foehn wind events. We focus on data from the Mc Murdo Dry Valleys as an example, however, due to the unsupervised nature of these approaches, our solutions can recognise a more dynamic definition of foehn wind events and are therefore, independent of the location. The first approach is based on multivariate time-series clustering, while the second utilises a deep autoencoder-based anomaly detection method to identify foehn wind events. Our best model achieves an f1-score of 88%, matching or surpassing previous machine-learning methods while providing a more flexible and inclusive definition of foehn events. 
Earth’s magnetosphere dynamics during “forced breathing” due to solar wind periodic density structures
Authors: Di Matteo Simone , Kepko Larry , Viall Nicholeen , Breneman Aaron , Halford Alexa , Villante Umberto
Published: February 2023

In the solar wind density, we often observe periodic fluctuations on time scales ranging from a few minutes to a few hours which we refer to as Periodic Density Structures (PDSs). The PDSs belong to the class of “meso-scale structures” with radial length scales greater than or equal to the size of the Earth’s dayside magnetosphere. The periodic character of these transients (≈0.2-4.0 mHz) can determine periodic compressional fluctuations of the Earth’s magnetic field at similar frequencies (“forced breathing” mode). The corresponding time scales overlap with the frequency range of Pc5 Ultra Low Frequency (ULF) waves (≈1.7-6.7 mHz). The compressional “forced breathing” fluctuations are often global and impact the entire Earth’s magnetosphere system/dynamics.  Using a recently developed spectral analysis approach applied to magnetic field observations at satellites and ground stations, we were able to differentiate directly driven magnetic field oscillations from Pc5 ULF waves triggered by other sources. Here, we discuss clear examples of such a directly driven process also showing effects on radiation belt electron dynamics and loss.
Are rock glaciers preferential meltwater pathways to alpine aquifers?
Authors: Charonnat Bastien , Baraer Michel , McKenzie Jeffrey M. , Valence Eole , Masse-Dufresne Janie
Published: February 2023

A limitation in generating reliable projections of the impact of climate change on subarctic glacierized watersheds is a lack of understanding of the involved processes. While glaciers are often the targets of glacierized watershed research, glaciers are only one of the many features controlling headwater hydrology. Recent studies suggest that the contribution and evolution of other hydrological components under climate change conditions, as well as their interactions with groundwater and surface runoff, must be considered to fully predict future climate change impacts. For example, rock glaciers are recognized for their hydrogeological significance, but their hydrologic processes remain understudied. We present a research program focused on a 5 km2 glacier and rock glacier continuum in the upper section of Shar Ta Gà’ (Grizzly Creek) in the Kluane First Nation territory, Yukon, Canada. The continuum is characterized by the absence of an apparent surface hydrology outlet and no substantial groundwater exfiltration has been detected in the Shar Ta Gà’ River situated directly downstream of the rock glacier. Some diffuse groundwater seepages have been mapped but their yield represent a fraction only of the volumes that are expected from the glacier drainage area.We apply a multimethod approach (including geophysics, hydrochemistry, and UAV based surveying) to characterize the hydrological and hydrogeological behavior of the Shar Ta Gà’ rock glacier in a context where drilling is prohibited. Here we present results from a distributed hydrologic monitoring network of extreme precipitation events that occurred between 2018 and 2022. The network records water pressure, electrical conductivity, water temperature, hydrometeorological data and time lapse images. The results depict the rock glacier as a complex, multi-channel, evolutive hydrogeological system that collects water from upstream channels and from a porous surface. The water is distributed among different reservoirs and/or preferential channels. The rock glacier appears being a node in the hydrological and hydrogeological system, collecting the waters from the continuum and allowing their transfer to granular aquifers and possibly fractured aquifers.
Enhanced Light Absorption and Radiative Forcing by Black Carbon Agglomerates
Authors: Kelesidis Georgios , Neubauer David , Fan Liang-Shih , Lohmann Ulrike , Pratsinis Sotiris
Published: February 2023

The climate models of the Intergovernmental Panel on Climate Change list black carbon (BC) as an important contributor to global warming based on its radiative forcing (RF) impact. Examining closely these models, it becomes apparent that they might underpredict significantly the direct RF for BC, largely due to their assumed spherical BC morphology. Specifically, the light absorption and direct RF of BC agglomerates are enhanced by light scattering between their constituent primary particles as determined by the Rayleigh–Debye–Gans theory interfaced with discrete dipole approximation and recent relations for the refractive index and lensing effect. The light absorption of BC is enhanced by about 20 % by the multiple light scattering between BC primary particles regardless of the compactness of their agglomerates. The resulting light absorption agrees very well with the observed absorption aerosol optical depth of BC. ECHAM-HAM simulations accounting for the realistic BC morphology and its coatings reveal high direct RF = 3–5 W/m2 in East, South Asia, sub-Sahara, western Africa, and the Arabian peninsula. These results are in agreement with satellite and AERONET observations of RF and indicate a regional climate warming contribution by 0.75–1.25 °C, solely due to BC emissions.
Influence of Azolla incorporation and/or dual cropping on CH4 and N2O emissions from flooded rice paddy systems
Authors: Kimani Samuel Munyaka , Bimantara Putu Oki , Kautsar Valensi , Hattori Satoshi , Tawaraya Keitaro , Sudo Shigeto , Tokida Takeshi , Cheng Weiguo
Published: February 2023

Azolla, a common aquatic fern has been used successfully as a dual crop with lowland rice. It grows rapidly and fixes atmospheric nitrogen for rice paddy. However, its ecological significance especially on greenhouse gases emissions remains unclear. Three independent experiments -two pot (2016 and 2017), and one field in 2019- were conducted to investigate the effects Azolla (A. filiculoides Lam.) either or both as dual cropping and green manure along with rice plant on simultaneous methane (CH4) and nitrous oxide (N2O) emissions from constantly flooded paddy soil. Under pot setups, dual cropping Azolla as a cover with rice plant significantly decreased seasonal CH4 emission by 34.7%, with no effect on N2O emissions. Suppressed CH4 emission was likely due to an increase in dissolved oxygen concentration and redox potential at the soil-water interface simulating CH4 oxidation. However, incorporation of Azolla as green manure into the soil plus dual crop in conjunction with chemical fertilizers significantly increased CH4 emission by 37.5% but decreased N2O emission by 74.5%. The significantly higher CH4 and lower N2O emissions were attributed to the readily decomposable incorporated Azolla, acting both as a source of CH4 production and N2O reduction. Contrary to the pot observations, application of Azolla as a dual crop in conjunction with chemical fertilizer or incorporated as green manure plus dual cropping in the field did not significantly affect seasonal CH4 emissions, but significantly increased cumulative N2O emissions at the middle rice growth stages by 645%—816%, and the total seasonal emission 3.4-fold. The higher N2O emissions were partly attributed to large quantities of exogenous organic carbon resulting from the accelerated growth and subsequent senescence of Azolla cover applied as a dual crop as impacted by higher summer air temperatures. Our observations suggest that dual cropping of Azolla with rice has the potential to reduce CH4 emissions from flooded rice paddies. Conversely, incorporation of Azolla as green manure into the paddy soil plus dual cropping in conjunction with or without chemical fertilizers indicates an inconsistent relationship between CH4 and N2O emissions. Long-term studies are needed to evaluate the relationship between leguminous cover crops and their effects on factors influencing CH4 and N2O emissions from continuously flooded rice paddies.
Linking exploratory scenarios to process-informed insights in climate vulnerability assessments
Authors: Kucharski John , Steinschneider Scott , Olszewski Jennifer , Herman Jonathan , Rahat Saiful , Ray Patrick , Arnold Wyatt , Maendly Romain
Published: February 2023

The threat that climate change poses to water resource systems has led to a significant and growing number of impact studies. These studies tend to follow two general methodological approaches: (1) top-down, process-based studies driven by projections of future climate change supplied by downscaled general circulation models (GCMs), and (2) bottom-up, vulnerability-based studies driven by exploratory scenarios. Top-down studies generate realistic climate scenarios, but computational burdens limit the ensemble size. As a result, critical vulnerabilities may be left unexplored. Bottom-up approaches make it possible to assess a wide range of scenarios, but usually without connection to physically plausible climate processes, limiting their utility in adaptive planning. This study develops process-informed exploratory scenarios that bridge the gap between top-down and bottom-up methods. This hybrid approach yields several advantages. First, emerging vulnerabilities associated with non-linear hydrologic changes are linked to thermodynamic and dynamic climate drivers modeled in the GCMs with differential likelihoods and plausible ranges of change. This provides a transparent link between stakeholder defined vulnerabilities and climate processes that is often missing in bottom-up assessments. Second, non-linear shifts in vulnerability are directly linked to specific climate drivers, through the systematic perturbation of process informed climate variables. Making this connection in top-down assessments is difficult since the climate response to an emissions scenario is modeled as part of an endogenous process. The hybrid approach developed by this study is presented with a case study in the Tuolumne River watershed; through which thermodynamic and dyanamically guided climate scenarios were created by a process-informed stochastic weather generator to evaluate flood and drought related performance vulnerabilities at the New Don Pedro Dam near the watershed’s outlet. This case study finds that flood and drought performance at the dam is more sensitive to process-informed climate drivers than less theoretically grounded delta shifts precipitation, and non-linear system responses to climate drivers are revealed through the systematic perturbation process-informed climate variables.
Atmosphere and fire interactions from the New Zealand experimental burn campaigns
Authors: Katurji Marwan , Zhang Jiawei , Valencia Andres , Lin Dongqi , Strand Tara , Pearce Grant , Finney Mark , Clements Craig , Gross Shana
Published: February 2023

Wildfires are increasing in intensity, frequency, and occurring earlier and later than normal on the seasonal timeline. Coupled atmosphere-flame-fuel dynamics makes wildfire a difficult phenomenon to understand and predict across its temporal and spatial spectrum of scales. This is especially true at the turbulence scale where rapid fluctuations of near-surface wind velocity and temperature within the atmosphere-fire boundary layer can control fire spread rates and extreme fire behavior. Appropriate observations from wildfires suitable for process-based investigations of coupled atmosphere-fire boundary layer dynamics do not exist, instead experimentally controlled fire burns are usually carried out. These experiments rely on repeated short-term wind driven fires that are usually restricted to certain meteorological regimes. Experimental design remains a challenging endeavor, which still lacks spatially coherent ambient and fire-induced atmospheric observations for understanding coupled dynamics. We have carried out several experimental fire burns in New Zealand for short stubble wheat and more dense and higher gorse shrubs. Our observations covered fuel properties, atmospheric turbulence, and flaming zone behavior. We have used uncrewed aerial vehicles carrying high speed infrared and visible video cameras, along with in-situ eddy covariance towers for ambient and fire-induced turbulence heat and momentum measurements. Some methodological highlights include the combination of image processing techniques, fuel density maps from aerial Lidar, and atmospheric turbulence structure analysis. We present a synthesis of research findings over the last two observational campaigns and introduce our new objectives for the upcoming crown fire forest canopy fire experiments. In addition, we discuss large eddy simulations of carefully designed numerical experiments allowing for a better understanding of the fire-atmosphere energetics at the atmospheric boundary layer scales.
The TSIS-2 TIM Instrument Pre-Flight Calibration and Uncertainty
Authors: Thiemann Ed , Heuerman Karl , Villani-Davila Andres , Richard Erik
Published: February 2023

The total solar irradiance (TSI) is Earth’s primary source of energy, and accurate knowledge of its value and variability is crucial for understanding Earth’s climate and variability. In order to continue the existing 44 year data record of TSI measurements from space, NASA is developing the Total and Spectral Irradiance Sensors (TSIS) -2 mission. TSIS-2 consists of the Total Irradiance Monitor (TIM) and Spectral Irradiance Monitor (SIM) on a free flyer satellite, with an anticipated launch in the latter half of 2024. The TSIS-2/TIM is the latest iteration of the TIM instrument, prior versions of which flew onboard the SORCE, TCTE and TSIS-1 missions, and a direct rebuild of the TSIS-1 instrument. We present the pre-flight ground calibration of the TSIS-2/TIM instrument and its uncertainties. A key difference between the calibrations of the TSIS-1 and TSIS-2 instruments is the use of a novel low noise ambient temperature radiometer for TSIS-2 that significantly reduces the uncertainty in validating the component level calibrations through an end-to-end measurement. We compare component level (e.g. aperture area, detector reflectance, etc.) measurements and uncertainties for TSIS-2 with those from TSIS-1, and focus on areas where the uncertainty analysis differs from that applied to TIM instruments on prior missions and the implications of these differences.
Earth’s Wandering Rotation Axis as a Diagnostic for Global Mantle Convection Models
Authors: Calvelage Christopher M. , Colli Lorenzo , Wu Jonny , Lin Yi-An
Published: February 2023

Dynamic topography is the change in topography that arises from viscous flow within the Earth’s mantle. As such, dynamic topography is sensitive to past mantle flow states. Making predictions of dynamic topography through time often relies on complex mantle convection models. To better constrain mantle convection models, we compare their implied True Polar Wander (TPW) paths for a range of model parameters. TPW is the re-orientation of a planetary solid body with respect to its rotation axis and may be produced by large scale mass redistributions on the Earth’s surface or within the mantle that perturb the Earth’s moment of inertia.Here we compare TPW histories estimated from two global plate tectonic reconstructions that were assimilated into the TERRA mantle convection code: (1) the widely-used Earthbyte global plate model (‘corrected R’ Matthews et al., 2016); and (2) TOMOPAC-22, a newly developed global plate tectonic model of the circum-Pacific using structurally-restored slabs from mantle seismic tomography (Wu et al., 2022). The time series of geodynamically-modeled mantle states are used to calculate synthetic TPW paths from perturbations in components of Earth’s moment of inertia from mass redistribution within the mantle; multiple (>10) viscosity-depth profiles were considered. We test these modeled TPW paths by comparing them against published paleomagnetic observations (Torsvik et al., 2012; Besse and Courtillot, 2002). Predicted TPW for plate Model 1 ranges widely (~90°) in azimuth from 120°W to 59°E with no consistent pattern across viscosity profiles. TPW rates reach maximums of 1.1°/Myr with excursions of ~25°. In contrast, predicted paths for Model 2 cluster within a smaller ~30° azimuthal range centered around ~29°E irrespective of the viscosity profile.  Predicted maximum rates were up to ~2°/Myr with excursions of up to 30°. Temporally, predicted paths for Model 2 drift toward northern Russia and then veer towards Greenland. Depending on the viscosity profile used some predicted TPW paths undergo stillstands from ~80 to ~30 Ma.  Ultimately, most model scenarios show longitudinal misfits up to 60° with observed paleomagnetic data; modeled TPW rates were within observed and theoretical ‘speed limits'. We discuss similarities and differences between our preliminary TPW history results and paleomagnetic observations, with a goal of developing an effective TPW test for constraining geodynamic parameters, plate tectonic reconstructions, and dynamic topography through time.
Ganymede’s internal structure after Juno and before JUICE.
Authors: Ermakov Anton , Akiba Ryunosuke , Gomez Casajus Luis , Zannoni Marco , Keane James , Tortora Paolo , Park Ryan , Buccino Dustin , Durante Daniele , Parisi Marzia , Stevenson David , Zhang Zhimeng , Brown Shannon , Levin Steven , Bolton Scott
Published: February 2023

We use the magnetic and gravity field data jointly to place constraints on the internal structure of Ganymede. The magnetic induction constraint comes mostly from the Galileo data, as the Juno flyby occurred when Ganymede was near the center of the magnetodisk, thus leading to low sensitivity to magnetic induction. The gravity field model of Ganymede jointly derived from the Galileo and Juno data to place constraints on Ganymede’s internal structure. Unlike in the previous works, the hydrostaticity was not imposed on the degree-2 gravity coefficients. Thus, despite including additional data from Juno, the uncertainties on the degree-2 coefficients increased. In addition, we explicitly treat the effect of non-hydrostaticity on the derived moment of inertia and find significantly wider confidence intervals on the moment of inertia. This leads to a larger allowed parameter space for the internal structure model.The new gravity solution confirms the past detection of non-hydrostatic anomalies. In our analysis, localized non-hydrostatic features with amplitudes higher than those found on Titan by the Cassini mission are identified. Titan is a useful comparison case as it shares with Ganymede nearly the same mean radius, mean density, and therefore, surface gravity. Thus, the non-hydrostatic deviations of the same amplitude either in shape or in gravity would correspond to approximately the same level of non-hydrostatic stress. On Titan, the gravity field for degree l > 2 reaches at most 5 mGal (Durante et al., 2019), which is a factor of 5 smaller than the largest anomalies found on Ganymede. One key difference between the two bodies is the lack of atmosphere-based erosion processes on Ganymede. Such erosional processes could have led to faster removal of non-hydrostatic signals at Titan reducing the amplitude of its gravity anomalies. In addition, Titan’s outer shell could be thinner and, therefore, less rigid than that of Ganymede, thus not being able to support as much non-hydrostaticity.Further insights on Ganymede’s interior will be coming from the JUICE mission in the next decade. Currently, the lack of an accurate shape model prevents separating degree-2 hydrostatic and non-hydrostatic contributions. Combined gravity, topography and rotation data acquired by JUICE will be crucial in determining the non-hydrostatic contribution to the degree-2 field to constrain Ganymede’s internal structure.
Tracking the pumice rafts from the recent eruption of the submarine volcano Fukutoku-Okanoba, Japan using Satellites and Lagrangian Particles tracking
Authors: Park Young-Gyu , Iskandar Mochamad Riza , kim Kwangseok , Jin Hyunkeun
Published: February 2023

On 13 August 2021, the Fukutoku-Okanoba submarine volcano in the North Pacific Ocean was erupted. Satellites detected many pumice rafts that drifted westward to reach southern Japan in about two months. To cope with potential danger due to the pumice rafts, it is crucial to predict their trajectories. Using a Lagrangian particle tracking model, the trajectories of the rafts were investigated. The model results showed strong sensitivity to the windage coefficient of pumice rafts, which is uncertain and could cause large errors. By comparing the model results with satellite images using a skill score, the distance between a simulated particle and the nearest observed raft divided by the travel distance of the particle, an optimal windage coefficient was estimated. The optimal windage coefficients ranging between 2 to 3% produced pathways comparable to the obervation using satellites. The pumice rafts  moved from Fukutoku-Okanoba, toward the Ryukyu Islands for approximately two months before being pushed toward Taiwan by the intensified wind. The techniques presented here may become helpful in managing coastal hazards due to diverse marine debris.
Hydroponics in the Urban Classroom: Learning geoscience in the classroom while addressing issues on food justice.
Authors: Castro-Skehan Carolina
Published: February 2023

Students between the ages of 13-18 are required to take a general Earth Science course either in middle school as part of an accelerated  program or in high school as a requirement for graduation in New York State.  Many students find this material dry, uninteresting and irrelevant to the pressing issues they are facing in their community. Most importantly, they find the global issues discussed in a typical Earth Science class as being esoteric or too large in scope for any individual like themselves to determine solutions.Enter hydroponics, a useful tool for students to learn valuable lessons on geoscience and sustainability in the classroom while also addressing issues the students in my community face on food justice. This year at my school, Comprehensive Model School Project, we incorporated a fully functioning hydroponics laboratory into our curriculum with the potential to produce over 200 pounds of fresh produce per year. In our hydroponics class we have delved deeper in many areas of geoscience and environmental studies and how they are connected with issues in our school community. Students learned valuable information connected to soil science, the hydrologic cycle and factors that affect plant growth. Incorporating hydroponics into our classroom has also been a valuable opportunity for students to learn about the challenges of food justice, as it allows them to explore issues such as food security, urban agriculture, and the environmental impacts of traditional agriculture. Hydroponics in the classroom is more than simply growing your own food without soil, students learn the importance of access to fresh, healthy food and the ways in which urban agriculture can help address these vital issues of food insecurity in their own communities.    
Connectivity of geoelectric network before strong earthquakes
Authors: Chen Hong-Jia , Chen Chien-Chih
Published: February 2023

Earthquakes are reported to relate to rupture phenomena in complex self-organizing systems. Hence, the earthquake rupture is regarded as a critical point. The preparation process of an earthquake could be considered as the crustal system approaching this critical point. Complex dynamical systems can have critical tipping points at which a sudden shift to a contrasting dynamical regime may occur; in the meantime, the time series of the systems can behave much differently. Although it is extremely challenging to predict such critical points before they are reached, work in different scientific fields is now suggesting the existence of generic early-warning signals that may indicate a wide class of systems if a critical threshold is approaching. Those precursory signals include increasing correlations and variance, varying skewness, and so on. The critical transition of a system includes spatial criticality and temporal criticality. In this study, we attempt to research the spatial and temporal criticality of the crustal system by using the self-potential (SP) signals of the Taiwan Geoelectric Monitoring System (GEMS). The GEMS network consists of 20 SP stations with an interstation distance of 50 km. We calculate the correlations of the daily signals between any two stations, which formed an adjacency matrix. Then, we estimate the connectivity density based on the adjacency matrix and compare the daily connectivity density time series with ML ≥ 5 earthquakes. We would expect to find out high connectivity densities before a strong earthquake. This would mean that earthquake-related telluric currents flow out through the GEMS stations during the earthquake preparation process; hence, the SP signals of most stations would almost be connected. As a result, we might establish an earthquake forecasting technique using the SP data based on the concept of the critical-point theory.