bluuebunny/crossref_metadata_2025 huggingface dataset:
Stratospheric gravity waves in high-resolution global models
Authors: Stephan Claudia
Published: February 2023

As we enter the age of exascale computing, more and more global scale simulations with horizontal grid spacings in the range of 1-10 km become available. Yet, not the full spectrum of gravity waves (GWs) is resolved and new challenges emerge, some of which are directly linked to the representation of convection, which is only partially resolved, but the most important source of GWs in the tropics.Unlike most climate models that use parameterizations for GWs, the DYAMOND simulations reproduce detailed, satellite-observed features of the global GW momentum flux (GWMF) distribution including the zonal mean. This can be attributed to realistic GWs from convection, orography and storm tracks. Yet, the GWMF magnitudes differ substantially among simulations. Differences in the strength of convection may help explain differences in the GWMF between simulations of the same model in the summer low latitudes where convection is the primary source. For ICON, simulations with explicit convection show 30-50% larger zonal-mean momentum fluxes in the summer hemisphere subtropics than simulations with parameterized convection. Explicit convection is associated with stronger updrafts and GW sources.Since any kind of observations can only see a fraction of the GW spectrum, we also analyzed the spectra of the horizontal motions associated with inertia GWs and Rossby waves, respectively. A fundamental characteristic of the atmosphere is the distribution of wave energy across different horizontal scales. Observations and numerical modelling have supported the idea of a canonical energy spectrum. Horizontal kinetic energy scales with the horizontal wavenumber k as k**-3 at large scales with a transition towards k**-5/3 at mesoscales.The simulations produce the expected canonical shape of the spectra, which is encouraging given that some models are stripped down to a minimum set of physical parameterizations. Yet, total energy levels, spectral slopes at sub-synoptic scales, and spectral crossing scales differ significantly. The contribution of inertia GWs to the total wave energy differs by factors of up to two between the simulations. The crossing scales between the inertia GW and Rossby wave spectra also differ by a factor of about two between the simulations and depend mostly on the ratio of integrated wave energies, rather than on spectral slope or details of the spectral shape. The spectra exhibit little variability in time and can serve as an almost instantaneous diagnostic.
An investigation of high frequency seismic tremor on Mt Etna
Authors: Weber Maurice , Bean Christopher , Lokmer Ivan , Smith Patrick , Zuccarello Luciano , De Angelis Silvio , Minio Vittorio
Published: February 2023

High frequency seismic data (> 10 Hz) on volcanoes have traditionally been less studied as precursory seismicity to volcanic eruptions is dominated by lower frequency signals. However, inspection of newly acquired data during a field campaign between July and September 2022 from individual high sampling rate seismic stations on Mt. Etna reveals the presence of high frequency (10-90Hz) signals, which are poorly understood. In an attempt to determine their location, mechanisms and wavefield properties, we deployed 104 nodal seismic sensors, mainly in 6 tuned circular array configurations consisting of several rings with increasing radius and number of nodes per ring around a central station. The nodes record at a sampling rate of 250Hz (125Hz Nyquist) and the frequency content of the recorded seismicity shows signals up to about 100 Hz. In addition to the high frequency nodes, we also deployed a profile consisting of 11 elements (infrasound, short period) as well as four broad band sensors.A variety of signals were recorded, with coherent signals on different stations across the full spectral range. Thus far initial multi-array beamforming has been applied to the data, demonstrating a range of locations which varies depending on the frequency range looked at. Whilst sources near the summit region are most common (especially at frequencies below 5 Hz), there are also other locations from which tremor emanates, opening questions about their origin.  Comparisons with infrasound, gas and weather data are ongoing, in an effort to shed light on the sources of these unusual signals.
Climatic against land use variability impact on soil erosion in two contrasting environments
Authors: Cerdan Olivier , Landemaine Valentin , Foucher Anthony , Desprats Jean-François , Evrard Olivier , Grangeon Thomas , Chabert Clément , Salvador-Blanes Sébastien
Published: February 2023

At continental and geological time scales, tectonic forces and climate are the first landscape evolution drivers. However, since the Neolithic, human is recognised as being a new geomorphic agent, indirectly or directly moving significant amount of materials across landscapes. In a context of global changes, when both climate and human activities are rapidly evolving, the question of the relative contribution of climate variability and anthropogenic activities to soil erosion remains poorly quantified. Understanding this contribution is however key to the design of appropriate soil erosion management plans. Based on two catchment-scale hydrosedimentary observatories, the objective of this study is to quantify the relative importance of climate variability and land use change on the erosive response of two headwater catchments located in contrasted environments. The first study area is in a volcanic tropical island and the second one is in a lowland, intensively cultivated plain under an oceanic temperate climate. More particularly, we will investigate the importance of rainfall and associated flood events intensity and frequency on the water and sediment fluxes. The influence of these temporal dynamics (i.e. frequency/intensity of events) will be studied according to different land uses, as the two questions (spatial/temporal variabilities) are closely interlinked.
Linking remotely sensed ecosystem resilience with forest mortality across the continental United States
Authors: Tai Xiaonan , Trugman Anna , Anderegg William
Published: February 2023

Episodes of forest mortality have been observed worldwide associated with climate change, impacting species composition and ecosystem services such as water re- sources and carbon sequestration. Yet our ability to predict forest mortality remains limited, especially across large scales. Time series of satellite imagery has been used to document ecosystem resilience globally, but it is not clear how well remotely sensed resilience can inform the prediction of forest mortality across continental, multi-biome scales. Here, we leverage forest inventories across the continental United States to systematically assess the potential of ecosystem resilience derived using different data sets and methods to predict forest mortality. We found high resilience was as- sociated with low mortality in eastern forests but was associated with high mortality in western regions. The unexpected resilience–mortality relation in western United States may be due to several factors including plant trait acclimation, insect popula- tion dynamics, or resource competition. Overall, our results not only supported the opportunity to use remotely sensed ecosystem resilience to predict forest mortality but also highlighted that ecological factors may have crucial influences because they can reverse the sign of the resilience–mortality relationships.
Using a new geophysical tool for improving underground safety in mining and civil engineering: time-sequential muography
Authors: Holma Marko , Korteniemi Jarmo , Kuusiniemi Pasi , Zhang Zongxian
Published: February 2023

Tunnelling and underground mining face many risks threatening underground operations. Such hazards include sudden incidents of dangerous and violent rock bursts and cave-ins. The likelihood of these disastrous events increases as operations go deeper and the in-situ stresses increase. Triggers leading to such accidents can be regional seismic events related to faults and tectonically active contacts between rock types (e.g., dyke contacts). Therefore, it is paramount to know the locations of such pre-existing brittle rock structures, understand their 3D extent, and monitor their changes in time. This allows proactive measures to be taken and stresses to be mitigated before disastrous events occur.Muography is a novel and passive method for imaging rock densities. Muographical techniques can image and distinguish faults and dykes as long as their densities differ from the surrounding rock. Such anomalies are identified by collecting data and statistics on muons - elementary particles which form in the atmosphere and, at near lightspeed, penetrate all matter. The most energetic ones travel over 1 km in rocks. The number of muons coming from each direction reveals the density of the rock column the muons traversed through.Muography is conceptually akin to X-ray imaging: In both, the formed image relates to the density profile of the target, i.e., a higher-density medium stops more X-rays and muons than a lower-density medium. Images are reconstructed based on the attenuation of natural background radiation flux. Muography can yield both 2D radiography and 3D tomography density images based on the number of survey locations. A third option, time-sequential (time-lapse) muography, allows long-term monitoring of the target rocks and can detect if any changes occur within it as a function of time. This type of imaging works in both radiographical and tomographical modes.The flux of muons is high at ground level and decreases with depth as bedrock attenuates muons. This means that muon detectors located at shallow observation depths will be faster to record a statistically sound dataset and, as such, quicker in pinpointing any time-varying changes within the target density.We propose that stationary muography arrays in underground settings could map potentially risky bedrock structures and monitor their density-affecting changes over time. E.g., hidden faults may become visible due to the passing of seasons or after the passing of substantial rainfall as the excess water percolates through the mechanically broken fractures. Another advantage of the time-sequential approach is that it reveals if the studied structure is stable and time-invariant, i.e., no ongoing processes affect its density. Therefore, we propose that applying muography in underground spaces improves understanding of the conditions of the rock body and, hence, increases safety.We aim to conduct pilots for this application soon.
The valorisation of the (Geo)heritage between the Siret and Prut Rivers of the Moldavian Plateau (Romania)
Authors: Ana Maria Anastasiei , Lilian Niacșu
Published: February 2023

Geotourism has been attracting more and more interest of the scientific community and the authorities in charge of tourism management and marketing. In Romania, such interest has just started to build, most of geotourism-relate research focusing on montaineous areas and not having an unitary approach. One of the least explored regions in terms of geotourism valorisation is the Moldavian Plateau, which is representative for the hilly lands of Romania. The plateau covers the entire North-East area of the country (27,158 km2) and is heavily affected by both by surface denudation and gully erosion.The aim of the current study is to build an inventory of geomorphosites and geosites, that may help setting up the profile of the plateau. The transformations suffered by this landform unit over time motivate the need for an updated profile, which can be further integrated in future research works concerning the  creation of a gully-based geopark.The first step was to corroborate the already existing data on the location and size of the gullies. Further on, a list of evaluation criteria was established and applied in the consequent fieldwork stage. The geomorphosites and geosites were identified and located using qualitative a evaluation process aiming to determine the geomorphological intrinsic value, potential use, and required protection. In addition, a GIS-based methodology was implemented in order to build the profile of the Moldavian Plateau. Finally, the identification of the geomorphosites and geosites served to the proposal of  geotrails; which represent the basis for geotourism in the study area, as an alternative for local economic development. Geoparks have proven to be excellent tools for educating the public about Earth Sciences; and are also important recreational areas and favour significant sustainable economic development.Keywords: Geoheritage, Geoscience education, Gullies potential, Geosites, Geomorphosites.
Plastic film mulching combined with manure fertilizer application promotes microbial necromass carbon accumulation within soil macroaggregates
Authors: Liu Xu , Bol Roland , An Tingting , Liu Yaocen , Wang Hongbo , Peng Chang , Li Shuangyi , Wang Jingkuan
Published: February 2023

Plastic film mulching is a common agricultural management to increase crop yield in the dry and cold regions. The improved soil hydrothermal environment under mulching conditions could change soil microbial activities and soil aggregation, thereby affecting soil organic carbon (C) sequestration. However, it remains not clear that how mulching regulates microbial necromass C accumulation and distribution within soil aggregates, especially under different fertilizer applications. We analyzed the contents of fungal and bacterial necromass C (taking amino sugar as biomarkers) and their contributions to organic C within soil aggregates under mulching combined with different fertilization treatments (no fertilization, CK; inorganic fertilizer application, IF; and manure fertilizer application, MF) in a 900-day in-situ field experiment. On day 360, the contents of fungal and bacterial necromass C within macroaggregates were 25% and 12% higher in the mulching combined with IF treatment, and were 20% and 32% higher in the mulching combined with MF treatment relative to the corresponding no-mulching treatments, respectively. On day 900, the mulching combined with CK and IF treatments decreased microbial necromass C content within soil aggregates, while the mulching combined with MF treatment promoted microbial and fungal necromass C accumulation within macroaggregates (>0.25 mm), compared with the corresponding no-mulching treatments. Mulching increased the fungal/bacterial necromass C ratio within macroaggregates on day 900, but decreased this ratio within microaggregates during the whole incubation period compared with the corresponding no-mulching treatments. Moreover, microbial necromass C occupied 28%–43% and 40%–56% of organic C within macroaggregates and microaggregates on day 900, respectively. Overall, mulching combined with the application of manure fertilizer greatly promoted microbial necromass C accumulation, and thus increased organic C sequestration within macroaggregates.
Heterogeneous earthquake distributions and stress drop estimates along the Cascadia subduction megathrust and upper plate faults
Authors: Bilek Susan , Morton Emily
Published: February 2023

Slip observed within subduction zones falls within a broad range, with non-volcanic tremor (NVT), slow slip, repeating small earthquakes, to great earthquakes all contained within this spectrum.  The diversity of observed slip suggests diversity in fault zone conditions, which can be affected by a variety of factors, such as fluids, sediment inputs, upper plate structure, and topography on the subducting plate.  The role of subducting topography on seismicity appears to be regionally variable, with some bathymetric features leading to high slip during earthquakes, and others leading to plate creep and small earthquakes associated with upper plate deformation.  Seismicity characteristics in regions of subducting topography can be difficult to assess in many areas however, because traditional land-based seismic networks can easily miss offshore smaller earthquakes associated with this process. We use data from an amphibious seismic network deployed along the Cascadia subduction zone to examine seismic characteristics of thousands of newly detected and located earthquakes along the margin.  Over 5000 earthquakes in the catalog generally agree with asperity locations modeled from geodetic data and the 1700 M9 rupture, along with several clusters of upper plate earthquakes in areas of subducting topography.  Stress drop estimates, based on a spectral ratio technique, vary depending on earthquake location, with higher stress drop earthquakes occurring on the upper plate faults relative to the lower stress drop earthquakes occurring along the megathrust.  These variations may reflect important changes in fault conditions between upper plate splay faults and the megathrust.
Seismic imaging of lower Carboniferous volcanic intrusions along the SW edge of the East European Craton in Poland
Authors: Krzywiec Piotr , Poprawa Paweł
Published: February 2023

Until recently, early Carboniferous volcanic activity along the SW edge of the East European Craton (EEC) in Poland has been documented only by wells and, to some degree, by magnetic data. Recently, regional PolandSPAN seismic reflection survey, acquired by ION Geophysical above the entire cratonic edge in Poland, provided unique subsurface insight into this very important event of an extensive volcanic activity. This onshore seismic survey was acquired with ultra-long offsets (12 kms), tight station spacing (25 m), high fold (480) and was processed up to PSDM. 12 seconds record lengths of uncorrelated data provided imaging down to 60 km, with superior data resolution for the entire Phanerozoic sedimentary cover.In N Poland, within the Mazury High, where Palaeozoic sedimentary cover has been eroded prior to the Permo-Mesozoic deposition within the marginal part of the Polish Basin, the Tajno pyroxenite-syenite-carbonatite complex, the Ełk syenite massif, the Pisz gabbro-syenite massif and Mława syenite massif, all of early Carboniferous age, have been drilled by numerous wells. In the Baltic Basin, where the Ediacaran – Silurian sedimentary cover has been preserved, numerous wells documented doleritic sills of the same age. In this area, a complex system of strong amplitude seismic reflectors of length reaching up to 100 km has been detected using PolandSPAN seismic data. These seismic features are located within the crystalline basement of the Baltic Basin at depth of 7-14 km, and closely resemble lower-crustal reflections (LCR) documented e.g. within the basement of the North Sea basin.Another type of seismic features related to the lower Carboniferous volcanic intrusives has been documented in SE Poland within the Lublin Basin, where EEC crystalline basement is overlain by thick Ediacaran – Paleozoic – Mesozoic sedimentary cover. In this area, numerous wells encountered lower Carboniferous doleritic intrusions hosted by the Upper Devonian carbonates, and lower Carboniferous basaltic effusives. PolandSPAN data from the Lublin Basin revealed numerous saucer-shaped, strong amplitude seismic reflectors, characterized by lobate morphology and located at depths of 4-7 km, within the topmost Silurian–Lower Devonian section. Collectively, they form ca. 70 km long network of seismic reflectors. They were interpreted as saucer-shaped igneous sills, similar to igneous intrusions imaged by seismic data in other sedimentary basins. Some of these sills have been incorporated into the late Carboniferous compressional deformations of the frontal Variscan fold and thrust belt.This study was supported by NCN grant UMO-2021/41/B/ST10/03550.
The role of internal variability and feedbacks controlling AMOC stability
Authors: Romanou Anastasia , Rind David , Jonas Jeff , Miller Ron , Kelley Maxwell , Russell Gary , Orbe Clara , Nazarenko Larissa , Latto Rebecca , Schmidt Gavin A.
Published: February 2023

A bi-stable mode of the Atlantic Meridional Overturning Circulation (AMOC) is found in a 10-member ensemble simulation of the SSP2-4.5 scenario using the NASA GISS-E2-1-G climate model. Local feedbacks in the subpolar North Atlantic region in conjunction with internal variability in sea-ice transport and melt play a critical role in causing the divergent behavior of the AMOC in the ensemble members. While other fully coupled models have demonstrated the important role of surface freshening in leading to AMOC shutdown, either through hosing experiments or increased precipitation and greenhouse gas warming at high latitudes, in the GISS simulations, there are no external freshwater perturbations. This is the first time that a CMIP-class model has shown such a bifurcation across an initial condition ensemble. 
Sub-ice shelf circulation and melt rate variability in the Energy Exascale Earth System Model
Authors: Vankova Irena , Asay-Davis Xylar , Price Stephen
Published: February 2023

In-situ observations from the Filchner-Ronne Ice Shelf (FRIS) have uncovered dominant time scales of variability in basal melting and circulation beneath this extensive ice shelf. In particular, the data characterize mechanisms of seasonal and inter-annual variability in sub-ice shelf properties, and show that the amplitude of the variability over the past thirty years is very modest.Because accurate representation of variability under present-day climate is an obvious prerequisite for earth system models that aim to project climate under a future change, this new observational understanding presents an opportunity for critical evaluation and improvement of existing models. We focus on the Energy Exascale Earth System Model (E3SM) and through a series of simulations we investigate the impact of ocean mixing parameterizations on the variability in the FRIS cavity.
Is a Preceding Strong El Niño Required to Generate Multi-year La Niña?
Authors: Kim Ji-Won , Yu Jin-Yi , Tian Baijun
Published: February 2023

By analyzing observational data covering the period from 1900 to 2021, we show that the known mechanism linking multi-year La Niña with a preceding strong El Niño has been overemphasized. A majority of multi-year La Niña (64%; 7 out of 11 events) do not require a preceding strong El Niño to generate their 2nd-year La Niña. We find that the negative phase of the Pacific Meridional Mode (PMM) during 1st-year La Niña’s decaying spring, rather than the preceding strong El Niño, offers the key mechanism to produce 2nd-year La Niña, resulting in a multi-year La Niña. It is further found that the westward extension of the 1st-year La Niña cold sea surface temperature anomalies, which interacts with the eastern edge of the western Pacific warm pool, is a key factor inducing the negative PMM. The negative PMM mechanism to generate multi-year La Niña is also applied to the 3rd-year La Niña of multi-year La Niña, giving rise to a triple-dip event. The possible reason(s) how and why a multi-year La Niña can become either a double-dip or a triple-dip event will be discussed.
The sensitivity of internal solitary waves to localized patches of mixing
Authors: Castro-Folker Nicolas , Stastna Marek
Published: February 2023

While most theoretical work on internal waves idealizes the stratification, geophysical stratifications are typically much more complicated.  We build on recent work on nearly linear stratifications by adopting perturbations that take the form of a localized patch of mixing. We present a data-centric framework that seeks to identify which locations and widths of a mixing patch yield the largest effect on the structure of exact waves (computed via the Dubreil-Jacotin-Long equation), linear waves (computed via the longwave Taylor-Goldstein equation), and evolving nonlinear waves (via time-dependent simulations using the incompressible Navier-Stokes equations). We find that the vertical structure functions of linear waves are most sensitive to perturbations below (above) the pycnocline when the pycnocline is above (below) mid-depth; furthermore, as the pycnocline approaches mid-depth, the depth of the perturbation layer with the greatest impact approaches the depth of the pycnocline. In contrast, the centre streamwise velocity profile of a DJL wave is perturbed most by layers above (below) the pycnocline when the pycnocline is above (below) mid-depth. Finally, we present the results of simulations of evolving nonlinear waves, where we compare pairs of cases with and without a perturbation layer. Despite the presence of an initial patch of unstable fluid, the perturbation layer is sustained during the simulation; nevertheless, slight Rayleigh-Taylor instabilities are observed within and about the perturbation layer. Modulations in the horizontal velocity field about the leading solitary wave are compared with the results of the linear and DJL analyses.
Radiative forcing by stratospheric aerosol from volcanoes and major fires for the last 3 decades
Authors: Brühl Christoph , Schallock Jennifer , Lelieveld Jos , Rieger Landon
Published: February 2023

We present instantaneous forcing computed in a transient simulation with the chemistry climate model EMAC considering more than 600 explosive eruptions and plumes of major forest fires observed by limb scanning satellites in the period 1991 to 2021. If not available directly, perturbations of SO2 in the volcanic plumes, which we use as alternative to the "point source approach", were derived from observed extinctions. For the fires, black and organic carbon is injected at the top of the pyro-cumulonimbus and the resulting increase in extinction is compared with satellite data. Medium sized volcanic eruptions cause a total forcing of up to -0.35W/m2 at the top of the atmosphere while for the fires the forcing there can be positive (about 0.2W/m2).
Harnessing integrated hydrologic modeling to analyze the coastal impacts of groundwater-surface water interactions on beach surface stability and freshwater availability
Authors: Paldor Anner , Frederiks Ryan S. , Housego Rachel , Raubenheimer Britt , Elgar Steve , Stark Nina , Michael Holly A.
Published: February 2023

Coastal aquifers supply freshwater to nearly half of the world's population, and their importance for sustainable development in coastal areas is immense. Due to the proximity to the ocean, salinization is typically the biggest risk for coastal groundwater resources. Furthermore, the interactions between groundwater and surface water during coastal flooding often result in surface instabilities arising from elevated groundwater heads. Here, integrated hydrologic modeling is used to examine the effect of groundwater-surface water interactions on the salinity distribution in aquifers and on the stability of beach surfaces. The processes considered include multi-scale fluctuations in sea level (tides, storm surges, and glacial cycles). Results show that modern salt distributions may change even if the current conditions remain stable, when considering short- and long-term cyclical processes that aquifers are likely still responding to. It is also found that during coastal flooding, critical hydraulic gradients may develop, potentially destabilizing the beach surface. The distribution of these critical gradients depends on beach topography, with a non-trivial relationship between surface elevation and the location of critical gradients. These results mean that the interactions between groundwater and surface water likely play a pivotal role in the hydrologic state of coastal systems, with important implications for water resources management and for natural hazard mitigation.
Revisiting the stratospheric ozone response to global warming
Authors: Match Aaron , Gerber Edwin
Published: February 2023

In response to global warming, ozone is predicted to increase aloft due to stratospheric cooling but decrease in the tropical lower stratosphere. The ozone reductions have been primarily attributed to a strengthening Brewer-Dobson circulation, which upwells ozone-poor air. Yet, we find that strengthening upwelling only explains part of the reduction. The reduction is also driven by tropospheric expansion under global warming, which erodes the ozone layer from below, the low ozone anomalies from which are advected upwards. Strengthening upwelling and tropospheric expansion are correlated under global warming, making it challenging to disentangle their relative contributions. Therefore, chemistry-climate model output is used to validate an idealized model of ozone photochemistry and transport with a tropopause lower boundary condition. In our idealized decomposition, strengthening upwelling and tropospheric expansion both contribute at leading order to reducing tropical ozone. Tropospheric expansion leads to an upward shift in the tropospheric destruction of ozone—not to an upward shift in ozone itself—implying that tropopause-following coordinates do not generally remove the effects of tropospheric expansion on ozone.
Reactivating sealed joints: rock strength reduction and permeability enhancement … sometimes
Authors: Kushnir Alexandra , Heap Michael , Baud Patrick , Reuschlé Thierry , Schmittbuhl Jean
Published: February 2023

Rock masses are often criss-crossed by generations of discontinuities, including veins, fractures, and joints. The presence of fractures and joints can increase rock mass permeability and decrease rock mass strength. However, fluid flow within rock masses can result in secondary mineral precipitation within these spaces. Secondary mineralisation can reduce permeability, with important consequences for fluid flow in systems that rely on discontinuity-dominated permeable networks. Here we investigate if variably sealed joints can be reactivated during deformation and the role joint reactivation plays on permeability. We deformed 20 mm in diameter by 40 mm long cores of un-jointed and jointed (variably sealed) bedded sandstones. Samples were cored such that their dominant structural feature (i.e., bedding or joint) was oriented parallel, perpendicular, or at approximately 30° to the sample axis. We find that the permeability of the undeformed samples is sensitive to the presence and orientation of bedding. In jointed samples, well-sealed joints can act as barriers to fluid flow, but partially filled joints neither inhibit nor promote fluid flow with respect to their joint-free counterparts. While all rocks in this study deformed in the brittle regime under triaxial deformation conditions, the location of the experimentally induced fractures depends on the extent to which joints are sealed. The mineralisation that fills well-sealed joints also permeates the surrounding sandstone matrix, locally reducing porosity and forming a cohesive bond between the joint-fill and the host-rock that increases rock strength: experimentally induced fractures do not exploit pre-existing joint surfaces in these samples. By contrast, strain is localised on the joint surface in samples containing partially sealed joints and the strength of these samples is lower than their un-jointed counterparts. The permeability of all samples increased after deformation, but permeability increase was largest in samples with pre-existing, poorly filled joints. We conclude that partially sealed joints act as planes of weakness within rock masses and that their reactivation can result in significant permeability increase. Well-sealed joints, however, may locally increase rock strength and never become reactivated during deformation: consequently, these joints may never re-contribute to the permeability of a rock mass. These observations provide insight into how fluid flow in the crust may evolve, with possible implications for how these systems weather over time.
Quantifying Airborne Fraction Trends and the Ultimate Fate of Anthropogenic CO2 by Tracking Carbon Flows in a Simple Climate Model
Authors: Pressburger Leeya , Dorheim Kalyn , Keenan Trevor , McJeon Haewon , Smith Steve , Bond-Lamberty Ben
Published: February 2023

Carbon dioxide (CO2) concentrations have increased in the atmosphere as a direct result of human activity and are at their highest level over the last 2-3 million years, with profound impacts on the Earth system. However, the magnitude and future dynamics of land and ocean carbon sinks are not well understood; therefore, the amount of anthropogenic fossil fuel emissions that remain in the atmosphere (the airborne fraction) is poorly constrained. This work aims to quantify the sources and controls of atmospheric CO2, the fate of anthropogenic CO2 over time, and the trend and robustness of the airborne fraction. We use Hector v3.0, a coupled simple climate and carbon cycle model, with the novel ability to explicitly track carbon as it flows through the Earth system. We use a priori probability distribution functions for key model parameters in a Monte Carlo analysis of 10,000 coupled carbon-climate model runs from 1750 to 2300. Results are filtered for physical realism against historical observations and CMIP6 projection data, and we calculate the relative importance of parameters controlling how much CO2 ends up in the atmosphere. Unsurprisingly, we find that anthropogenic emissions are the dominant source of near- and long-term atmospheric CO2, composing roughly 45% of the atmosphere, which is consistent with observational studies of the airborne fraction. The overwhelming majority of model runs exhibited a negative trend in the airborne fraction from 1960-2020, implying that current-day land and ocean sinks are proportionally taking up more carbon than the atmosphere. Furthermore, when looking at the destination of anthropogenic fossil fuel emissions, only a quarter ends up in the atmosphere while more than half of emissions are taken up by the land sink on centennial timescales. This study evaluates the likelihood of airborne fraction trends and provides insights into the dynamics and destination over time of anthropogenic CO2 in the Earth system.
Climate-smart forest management may decrease vulnerability of forest carbon to disturbances
Authors: Piazza Natalie , Nevola Edoardo , Vacchiano Giorgio
Published: February 2023

Natural disturbances like windthrows or forest fires have an effect on the provision of ecosystem services like timber production, protection from natural hazards or carbon sequestration. After a disturbance, forests release large amounts of carbon and therefore change their status from carbon sinks to carbon source. However, forest management may improve the forest capacity to absorb carbon by decreasing the vulnerability to disturbances. In this study we used simulation tools ForestGALES (windthrow) and FlamMap (forest fire) to model the vulnerability to the two disturbances. We analysed forest stands prone to windthrow (in the Carnic Alps) and forest fire (in the Apennines) and proposed forest management in the most vulnerable forest stands, increasing their resistance to the respective disturbance. We simulated the future carbon stock and sink under two scenarios: (1) business-as-usual management, and (2) forest improved using climate-smart forest management to decrease the vulnerability to disturbances. Forest under business-as-usual management led to a decrease in total carbon. Using climate-smart management compared to business-as-usual resulted to an increase of carbon stocks (with additional increase in case of no disturbance). We showed that using disturbance simulation tools may help in decision making process to analyse the most vulnerable forest stands. In combination with simulations of future scenarios of carbon we may be able to direct the climate-smart forestry.
Are spatial and temporal patterns of landslide triggering events reflected in topography and sediment dynamics?
Authors: Campforts Benjamin , Duvall Alison , Shobe Charles , Tucker Gregory , Overeem Irina
Published: February 2023

Landslides alter the morphology and sediment dynamics of mountainous terrain. Here, we evaluate how the spatial and temporal variability of landslide triggering events adjust this footprint. We use the HyLands landscape evolution model that explicitly simulates the occurrence of landslide events as well as fluvial incision and sediment dynamics. Both existing landscapes as well as synthetically produced landscapes that evolve over geological timescales are considered. This enables us to identify the required magnitude and frequency of extreme events for them to be recorded in landscape morphology. Moreover, we compare the relative contribution of long-term tectonic processes versus spatially clustered extreme events in shaping mountainous terrain. Finally, we evaluate if and how the temporal occurrence of landslide-triggering events alter morphology. Here we compare two scenarios: a first one evaluates how a landslide-prone landscape responds to events that are uniformly spread through time, a second one tests how such a landscape responds to regionally synchronous events. This contribution aims to clarify the distinctive role of landsliding in shaping mountainous terrain, which will in turn contribute to understanding how landslide prone regions respond to spatial and temporal changes in extreme events.
Crop type mapping in Central and South Asia using Sentinel-1 and Sentinel-2 remote sensing data
Authors: Raab Christoph , Nguyen Viet Duc
Published: February 2023

Crop type information derived from satellite remote sensing are of pivotal importance for quantifying crop growth and health status. However, such spatial information are not readily available for countries in Central and South Asia, where smallholder farmers play a dominant role in agricultural practice, and food security. In this study, we provide insights into crop type mapping for three study sites in the region: 1) Panfilov District in Kazakhstan, 2) Jaloliddin Balkhi District in Tajikistan, and 3) Multan District in Pakistan. A collection of Sentinel-2 and Sentinel-1 satellite data was used along with the random forest classification algorithm. To train and validate the classification model, field data were collected between May and October 2022 in each of the study areas. Our main objective was to evaluate the performance of a combined Sentinel-2 and Sentinel-1 mapping approach in comparison to a single source result. In addition, this contribution will provide insights into the performance with regard to crop type mapping accuracy of different temporal data aggregation intervals. Preliminary results indicate a small increase in overall accuracy for a combined Sentinel-2 and Sentinel-1 mapping approach. However, Sentinel-2 data might be sufficient for reliable crop type mapping, in case cloud coverage is not a constraint. Future studies might consider evaluating the potential benefit of using a full Sentinel-1 data set without temporal aggregation for mapping crop types.
Finding Quaternary Seismogenic Activity Along the Eastern Periadriatic Fault System: Dating of Fault Gouges via Trapped Charge Methods
Authors: Prince Erick , Sumiko Tsukamoto , Christoph Grützner , Marko Vrabec , Kamil Ustaszewski
Published: February 2023

The Periadriatic Fault System (PAF) is among the largest and most important post-collisional structures of the Alps; it accommodated between 150-300 km of right-lateral strike-slip motion between the European and Adriatic plates from about 35 until 15 Ma. Recent GPS data suggest that Adria-Europe convergence is still being accommodated in the Eastern Alps. However, according to instrumental and historical seismicity records, seismotectonic deformation is mostly concentrated in the adjacent Southern Alps. In this contribution, we present our first results for dating earthquakes along the PAF during the Quaternary by applying two trapped charge dating methods. Both Electron Spin Resonance (ESR) and Optically Stimulated Luminescence (OSL) are especially useful as ultra-low temperature thermochronometers due to their dating range (a few decades to ~1 Ma) and low closing temperature (below 100°C). We aim to show which segments of the PAF system accommodated seismotectonic deformation by directly dating quartz and feldspar from fault gouges. For ESR, we measure the signals from the Al center in quartz following the single aliquot additive (SAAD) and single aliquot regenerative (SAR) protocols, focusing on the 100-150 µm grain size fraction. For OSL, we measure the IRSL signal at 50°C (IR50) and the post-IR IRSL signal at 225°C (pIRIR225) on potassium feldspar aliquots of the 100-150 µm grain size fraction. Our ESR results indicate the PAF system accommodated seismotectonic deformation during the last 1 Ma, while the OSL signals for all samples were in saturation. The minimum ages obtained from OSL suggest that the events are likely not younger than 0.4 Ma. We also studied a segment of the nearby Lavanttal Fault, for which our ESR results suggest that the last earthquakes strong enough to produce sufficient shear heating to produce a partial reset on the geochronometer probably happened before 4 Ma.
Development of Dynamic Drought Vulnerability Assessment Considering Global Climate Change and Regional Water Demand-Supply Networks
Authors: Kim Tae-Woong , Kim Min Ji , Kim Jang-Gyeong , Yoo Jiyoung
Published: February 2023

Globally, drought affects different types of regions and countries, making it one of the most devastating natural disasters in terms of impacts on agriculture and food security, ecosystems, human health, and water resources. As the importance of integrated drought management including disaster risk reduction, climate change adaptation strategies, and national water policies is emphasized internationally, it is important to develop an effective water management technology for proactive drought response rather than reactive drought management to cope with drought disaster. In this study, we propose an approach to dynamic drought vulnerability assessment that can be used to secure elasticity for water demand and supply during drought event and further respond to a preemptive drought. Drought response and management based on this dynamic drought vulnerability assessment technology has consistency in that it promotes an internationally pursued convergence strategy for climate change adaptation and disaster risk reduction. The dynamic drought vulnerability assessment is based on the water demand-supply linkage assessment in various types of droughts. In other words, this is a technology for improving the ability to respond to drought through flexible water supply in the actual drought events. Dynamic drought vulnerability assessment produces various types of drought vulnerability map considering various scenarios of drought occurrence and socio-economic pathways according to climate change. For example, when combining hydrological drought scenarios considering climate change (25 types), water demand scenarios according to social/economic/environmental changes (3 types), water supply scenarios of drought damage/sensitivity by region (4 types), storage ratio scenarios of dam and reservoir (12 types), at least 2100 scenarios are produced as database. In the future, these results can be used as a basis for scientific decision-making in preparing countermeasures to improve resilience to drought.Acknowledgement: This work was supported by the Korea Environment Industry & Technology Institute (KEITI) through Water Management Innovation Program for Drought (No. 2022003610001) funded by Korea Ministry of Environment.
Core surface flow inversion using physics-informed neural networks
Authors: Li Jinfeng
Published: February 2023

Core surface flow inversion using physics-informed neural networks
Jinfeng Li (1) and Yufeng Lin (1)
(1) Department of Earth and Space Sciences, Southern University of Science and Technology, Shenzhen 518055, China.
Physics-informed neural networks (PINNs) have recently been widely used to solve PDEs or ODEs. An attractive feature of this method is that it can calculate the derivatives without truncation errors by the automatic differentiation method (Lu et al., 2021). Another advantage is that it can solve the inverse problem with slightly modified code for solving the forward problem (Raissi et al., 2020). In this study, we use the PINN to inverse the core surface flow from the geomagnetic observations. We start from the radial component of the induction equation under the frozen-flux approximation (Robert and Scott, 1965) and tangentially geostrophic flows assumption (Hills, 1979). Instead of using the large-scale approximation, which assumes the flows that generate the observed secular variation (SV) are large-scale, we model the flow field in the physic space and construct the unobserved magnetic field based on the power spectrum of numerical dynamo simulations. We examine the nonuniqueness of the inversion results by pre-setting the different initial parameters of the neural network. Our tests show that the uncertainty of large-scale flow field is small and the inversion scheme is robust.
We retrieve the core surface flow field between 2000 and 2020 using the core magnetic field model CHAOS-7 (Finlay et al., 2020). We then perform the dynamic mode decomposition method (DMD) (Schmid, 2010) of the retrieved core flow. This method decomposes the flow field and SV into several eigenmodes with time evolution. The consistency time evolution between the flow and the SV modes indicates the inversion algorithm is stable. Moreover, we calculate the secular acceleration (SA) of the magnetic field for each dynamic modes and find the mode with 8 years period can match the jerk events occurred in the equatorial region.
Reference

C. Finlay, C. Kloss, N. Olsen et al. 2020, The CHAOS-7 geomagnetic field model and observed changes in the South Atlantic Anomaly, Earth Planets Space, 72, 156.
G. Hills, 1979, Convection in the Earth’s Mantle Due to Viscous Shear at the Core-Mantle Interface and Due to Large-Scale Buoyancy. PhD Thesis, New Mexico State University, Las Cruces.
Lu, X. Meng, Z. Mao and G. E. Karniadakis, 2021, DeepXDE: A Deep Learning Library for Solving Differential Equations, SIAM Review, 63, pp. 208-228.
Raissi, A. Yazdani and G. E. Karniadakis, 2020, Hidden fluid mechanics: Learning velocity and pressure fields from flow visualizations, Science, 367, pp. 1026-1030.
H. Robert and S. Scott, 1965, On analysis of the secular variation. 1: A hydromagnetic constraint: Theory, Journal of Geomagnetism and Geoelectricity, 17, pp. 137-151.
J. Schmid, 2010, Dynamic mode decomposition of numerical and experimental data, J. Fluid Mech, 65, pp. 5-28.