bluuebunny/crossref_metadata_2025 huggingface dataset:
Multi-source observations of a coronal mass ejection front from low to middle corona
Authors: Stepanyuk Oleg , Kozarev Kamen
Published: March 2022

The shape and dynamics of coronal mass ejections (CMEs) varies significantly based on the instrument and wavelength used. This has led to significant debate about the proper definitions of CME/shock fronts, pile-up/compression regions, and cores observed in projection in optically thin vs. optically thin emission. Here we present an observational analysis of the evolving shape and kinematics of a large-scale CME that occurred on May 7, 2021 on the eastern limb of the Sun as seen from 1 au. The eruption was observed continuously, consecutively by the Atmospheric Imaging Assembly (AIA) telescope suite on the Solar Dynamics Observatory (SDO), the ground-based COronal Solar Magnetism Observatory (COSMO) K-coronagraph (K-Cor) on Mauna Loa, and the C2 and C3 telescopes of the Large Angle Solar Coronagraph (LASCO) on the Solar and Heliospheric Observatory (SoHO). We apply the recently developed Wavetrack Python suite for automated detection and tracking of coronal eruptive features to evaluate and compare the evolving shape of the CME front as it propagated from the solar surface out to 30 solar radii.
Multi-zonal parametric model of the Jovian synchrotron radiation belt updated from the Juno mission observations
Authors: Adumitroaie Virgil , Levin Steven , Oyafuso Fabiano , Santos-Costa Daniel , Bolton Scott
Published: March 2022

In Jupiter’s vicinity, Juno’s remote-sensing experiment, the Microwave Radiometer (MWR), captures thermal and non-thermal emissions from the atmosphere and magnetosphere. Furthermore, other scientific instruments on the spacecraft register the signatures of space charged particles and the planet’s magnetic field. The separation of contributions from several existing emission sources (cosmic microwave background, galactic emission, planetary thermal emission and synchrotron radiation belts) is a necessary step in the retrieval of atmospheric composition values from MWR’s low-frequency radiative observations.

The ad hoc multi-parameter, multi-zonal model of Levin et al. (2001) for synchrotron emission has been updated based on a subset of the MWR in-situ data. This model employs an empirical electron-energy distribution, which originally has been adjusted exclusively from Very Large Array (VLA) observations made prior to the Juno mission. The approaches considered and challenges confronted are discussed here. The model will be updated frequently as additional observations from the MWR and magnetometer instruments are taken into account.
Temporal evolution of Cumbre Vieja explosive activity and ash plumes from ground-based infrared and visible cameras
Authors: Birnbaum Janine , Lev Einat , Hernandez Pedro , Barrancos José , Padilla Germán , Asensio-Ramos María , Calvo David , Rodríguez Fátima , Pérez Nemesio , Calvari Sonia
Published: March 2022

During the main phase of the 2021 eruption of the Cumbre Vieja volcano (La Palma, Spain), eruptive activity was characterized by Strombolian eruptions, fire fountaining, white and grey ash and gas-dominated plumes, and lava effusion from multiple events. Over the period November 16 to November 26, we recorded continuous time-lapse IR images and opportunistic visible and IR videos of the vent from multiple ground-based locations. We measure the apparent area of the high-temperature gas-and-ash jet and fire fountaining from time-lapse images recorded between 1 and 60 frames/min to investigate the evolution of the explosive activity and of these plumes on minutes to days time scales. We compare plume size estimates from two different angles and vent-camera distances. We will explore periodicity and relationships between neighboring vents and discuss the implications for processes occurring in the shallow-most plumbing system of the volcano.
UAV Data Analysis in the Cloud - A Case Study
Authors: Kelka Ulrich , Peters Chris , Kaluza Owen , Klump Jens , Micklethwaite Steven , Reid Nathan
Published: March 2022

The mapping of fracture networks from aerial photographs, tracing of fault scarps in digital elevation models, and digitisation of boundaries from potential field data is fundamental to many geological applications (e.g. resource management, natural hazard assessment, geotechnical stability etc.). However, conventional approaches to digitising geological features are labour intensive and do not scale.

We describe how we designed an automated fracture detection workflow and implemented it in a cloud environment, using free and open-source software, as part of The Australian Scalable Drone Cloud (ASDC, https://asdc.io) national initiative. The ASDC aims to standardise and scale drone data, then analyse and translate it for users in academia, government, and industry.

In this use case, we applied automatic ridge/edge detection techniques to generate trace maps of discontinuities (e.g. fractures or lineaments). The approach allows for internal classification based on statistical description and/or geometry and enhances the understanding of the internal structure of such networks. Further, photogrammetry and image analysis at scale can be limited by the available computing resources, but this issue was overcome through implementation in the cloud. The simple methods l serve as a basis for emerging techniques that utilise machine learning to fully automate the discontinuity identification and represents an important step in the cultural adoption of such tools in the Earth Science community.

We deployed Open Drone Map (ODM) onto a cloud infrastructure to produce orthophoto mosaics from aerial images taken by UAV to implement this case study. We ported a fracture detection and mapping algorithm from Matlab to Python for the image analysis. The image analysis workflow is orchestrated through a Jupyter Notebook on a Jupyter Hub. The resulting prototype workflow will be used to better scope the services needed to manage the ASDC platform, like user management and data logistics.
Optimized Stochastically Perturbed Parameterization Scheme for the Soil Temperature and Moisture within an Ensemble Data Assimilation System
Authors: Lim Sujeong , Park Seon Ki , Cassardo Claudio
Published: March 2022

The ensemble data assimilation (EDA) system contains uncertainties both in initial conditions and model forecast. In general, the uncertainties are represented by the ensemble spread that is a standard deviation of background error covariance (BEC). However, this ensemble spread is usually underestimated due to insufficient ensemble size, sampling errors, and imperfect models: it often causes a filter divergence problem as the analysis ignores the observation due to insufficient model uncertainty. This phenomenon is also found in the coupled land-atmospheric modeling system, especially near the surface where the heat flux exchanges are crucial as the lower boundary conditions. Therefore, we have developed the stochastically perturbed parameterization (SPP) scheme for the Noah Land Surface Model (hereafter, SPP-Noah LSM) using the soil temperature and moisture within the coupled WRF-Noah LSM system to represent the near-surface uncertainty. It perturbs the soil variables by adding the random forcing to inflate the ensemble spread. In particular, the random forcing used in perturbation is controlled by the tuning parameters such as amplitude, time scale, and length scale, which vary depending on the target variables. To obtain the optimal random forcing parameters to the soil variables, we employed a global optimization algorithm --- the micro-genetic algorithm, which is based on the natural selection or survival of fitness to evolve the best potential solution. The optimization is conducted in each daytime and nighttime to consider the diurnal variations of soil variables. As a result, the soil temperature and moisture perturbations using the SPP-Noah LSM can indirectly inflate the ensemble BECs of temperature and water vapor mixing ratio through the heat flux changes, respectively, in the planetary boundary layer (PBL) of the EDA system. The SPP-Noah LSM with diurnal variations depicts reasonable ensemble spreads for soil variables, but the ensemble spreads for atmospheric variables from the propagation of the soil variable perturbations are less effective. Our results indicate that the inflated ensemble spread helps to produce an adequate analysis increment reducing the background error in the PBL.
10Be analysis in pyroxene - a method for routine chemical extraction
Authors: Balter-Kennedy Allie , Schaefer Joerg , Schwartz Roseanne , Penrose Laura , Lamp Jennifer , Winckler Gisela
Published: March 2022

We have developed a method for routine processing of pyroxenes for cosmogenic 10Be analyses, offering a multi-nuclide (3He/10Be) approach for mafic terranes. Analyzing multiple cosmogenic nuclides from the same rock/mineral (most commonly, 26Al/10Be and 10Be/21Ne in quartz) enables quantification of complex exposure histories, including burial times, and erosion and denudation rates. This requires measurement of at least two cosmogenic nuclides whose production ratios and systematics are well known. For example, in quartz-bearing lithologies, the 26Al-10Be pair is routinely used because the production ratio of ~7 is relatively well constrained. In mafic lithologies, the 3He-10Be pair is a viable candidate for multi-nuclide studies because 3He is routinely measured in pyroxenes, and preliminary studies demonstrate that beryllium extraction from pyroxene grains is possible. Despite the potential of this nuclide pair, there is not yet a simple method for extracting beryllium from pyroxenes given that this mineral has high elemental concentrations and retains meteoric 10Be within the crystal lattice. 

Here, we present a method for beryllium extraction from pyroxenes, modified from the extraction method in quartz, that will enable routine use of the 3He-10Be pair. We demonstrate that hydrofluoric acid leaching not only allows for separation of large amounts of clean pyroxene, even from fine-grained lithologies such as Ferrar Dolerite, but also successfully removes meteoric 10Be. The addition of a simple precipitation step prior to ion exchange chromatography adequately reduces the cation load, allowing us to proceed with the same beryllium extraction chemistry used for quartz. Together, this approach allows for routine processing for 10Be analyses in pyroxene. Using our 10Be measurements, we present a preliminary 10Be production rate in pyroxene, referenced to 3He, for the McMurdo Dry Valleys, Antarctica, meaning that the 3He-10Be pair can already be used to evaluate complex exposure histories. With this result, we are optimistic that the presented extraction method opens new opportunities for multi-nuclide applications in mafic lithologies. 
Time to Update the Split Sample Approach to Hydrological Model Calibration: A Massive Empirical Study
Authors: Shen Hongren , Tolson Bryan , Mai Juliane
Published: March 2022

Model calibration and validation are critical in hydrological model robustness assessment. Unfortunately, the commonly used split-sample test (SST) framework for data splitting requires modelers to make subjective decisions without clear guidelines.

A massive SST experiment for hydrological modeling is proposed and tested across a large sample of catchments to empirically reveal how data availability and calibration period features (i.e., length and recentness) simultaneously impact model performance in the post-validation period (e.g., forecasting or prediction), thus providing practical guidance on split-sample design. Unlike most SST studies that use two sub-periods (i.e., calibration and validation) to build models, this study incorporates an independent model testing period in addition to calibration and validation periods. Model performance of two lumped conceptual hydrological models (i.e., GR4J and HMETS) are calibrated and tested in 463 CAMELS catchments across the United States using 50 different data splitting schemes. These schemes are established regarding the data availability, length, and data recentness of the continuous calibration sub-periods (CSPs). A full-period CSP is also included in the experiment, which skips model validation entirely. The results are synthesized regarding the large sample of catchments and are comparatively assessed in multiple novel ways, including how model building decisions are framed as a decision tree problem and viewing the model validation process as a formal testing period classification problem, aiming to accurately predict model success/failure in the testing period.

Results span different climate and catchment conditions across a 35-year period with available data, making conclusions generalizable. Strong patterns show that calibrating to older data and then validating models on newer data produces inferior model testing period performance in every single analysis conducted and should hence be avoided. Calibrating to the full available data and skipping model validation entirely is the most robust split-sample decision. Findings have significant implications for SST practice in hydrological modeling. As the next phase of this study, results for discontinuous calibration sub-periods (DCSP) will be evaluated as an alternative SST design choice and contrasted then with the CSP results.
Internal Tide Scattering by an Isolated Cyclogeostrophic Vortex
Authors: Uncu Jeffrey , Grisouard Nicolas
Published: March 2022

Internal tides (ITs) are internal waves which oscillate at the tidal frequencies. ITs may cross entire ocean basins and along the way, they may be redirected, break, and dissipate. The latter is due to changes in stratification, bottom turbulence, wave-wave interactions, and of interest in this study, the scattering of ITs by balanced flow. Mesoscale wave-vortex interactions are characterized by low Rossby numbers. With the aid of satellite altimetry, the effects of mesoscale eddies on ITs has been used successfully to map low mode IT propagation.  In the submesoscale, these interactions become more complex, due to strong non-linearities, a partial breakdown of geostrophic balance, and intermediate scales for both balanced flows and ITs, which are hard to observe with current methods. However, the next generation of satellite altimetry, the Surface Water and Ocean Topography mission, will have fine enough resolution to begin to capture the submesoscale, which makes it an exciting time to explore wave-vortex interactions in this regime. We use the one-layer shallow water model to run idealized numerical simulations of a single wave mode propagating through a (cyclo)geostrophic vortex. By varying the Rossby number, which controls the strength of the vortex, and varying the relative scale of the vortex size to IT wavelength, we observe the IT energy redistribution at the lee side of a submesoscale vortex. We find that high Rossby numbers and relatively small waves will induce sharper deflections in wave propagation, which we quantify with energy flux calculations. By applying complex demodulation, we can filter the incoming plane wave to reveal the characteristic pattern of an isolated vortex scatter, which consists of three beams, two slightly skewed beams from the edge of the vortex, and one strongly skewed beam from the middle.
Numerical study of 2D & 3D ERT with sensitivity analysis for subsidence in the coal mining area
Authors: Rupesh Rupesh , Tiwari Prarabdh , Sharma Shashi Prakash
Published: March 2022

Subsurface cavities are mainly responsible for ground subsidence in and around coal mines. There is need to use an advanced high-resolution three-dimensional (3D) Electrical Resistivity Tomography (ERT) technique to detect anomalies and map subsurface precisely. The present study demonstrated the numerical evaluation of 2D and 3D-ERT for air-filled and water-filled cavities. Models simulated with reasonable resistivity values for voids and formations by considering bord and pillar mining environments in multilayer earth. Wenner, Wenner-Schlumberger, and Dipole-dipole arrays incorporated with and without a barrier to getting the best possible output. We used the Res2dinv and Res3dinv programs for data processing. 3D Dipole-dipole inverted geo-electrical section better showed the subsurface cavities signature than the results obtained from other applied arrays. The sensitivity section corresponding to used electrode configurations gives a more detailed picture of the subsurface for better interpretation. The 3D volume of the subsurface overcomes the limitations of 2D ERT to detect cavities within the coal seam.
Effect of Icelandic hotspot on Mantle viscosity in southeast Greenland
Authors: Barletta Valentina R. , van der Wal Wouter , Bordoni Andrea , Khan Shfaqat Abbas
Published: March 2022

Recent studies suggest the hotspot currently under Iceland was located beneath eastern Greenland at ~40 Ma BP and that the upwelling of hot material from the Iceland plume towards Greenland is ongoing. A warm upper mantle has a low viscosity, which in turn causes the solid Earth to rebound much faster to deglaciation. In the area of the Kangerlussuaq glacier, a large GPS velocities residual after removing predicted purely elastic deformations caused by present-day ice loss suggests the possibility of such fast rebound to little ice age (LIA) deglaciation. Here we investigate the lithospheric thickness and the mantle viscosity structure beneath SE-Greenland by means of model predictions of solid Earth deformation driven by a low viscosity mantle excited by the LIA deglaciation to the present day. From the comparison of such modeled deformations with the GPS residual, we conclude that 1) a rather thick lithosphere is preferred (90-100 km) 2) and the upper mantle most likely has a viscosity that changes with depth. Assuming a two layer upper mantle, it is not well constrained which part of the upper mantle has to be low, with a preference for low viscosity in the deeper upper mantle.

To understand such results we implemented forward modelling with more realistic earth models, relying on improvements in seismic models, petrology and gravity data. This yields 3D viscosity maps that can be compared to inferences based on the 1D model and forms the basis for 3D GIA models. The conclusion based on the 1D model can be explained with 3D Earth models. In the area of the Kangerlussuaq glacier the seismic derived viscosities prefer a higher viscosity layer above a lower viscosity one. This stems from the slow decrease in viscosity with depth. The layer that is characterized as shallow upper mantle still contains shallow regions with low temperatures, while the deeper upper mantle reaches low viscosities. Generally, for GIA earth models the “higher above lower” viscosity layering is unusual. However, the analysis of the 1D model clearly shows this to be one of the preferred model regions, in combination with a large lithosphere thickness of 100 km. This is a notable result that draws attention to the importance of shallow layering in GIA models. 
Methodological and analytical improvement of the ISotopic Acetylene Reduction Assay for the assessment of complementary biological nitrogen fixation in low activity samples
Authors: Haynes Shannon , Darnajoux Romain , Han Eunah , Zhang Xinning
Published: March 2022

Understanding the enzymes responsible for biological nitrogen fixation in the natural environment is crucial for understanding the global nitrogen cycle. The isotopic acetylene reduction assay (ISARA) is currently one of the only ways to distinguish between nitrogenase enzymes and it involves measuring the δ13C of ethylene generated via the reduction of acetylene. However, the classical method can only be applied to samples with ethylene concentrations >1,000 ppm which is limiting for environmental samples, where N2 fixation activity is generally low resulting in a low headspace ethylene concentration (<300 ppm).

Here we describe an improved analytical method for analyzing δ13C of ethylene using a homemade gas pre-concentration system and reproducible in-house standards developed from commercially available ethylene tanks. We also present a simple methodology using mutants of Azotobacter vinelandii (Mo-only and V-only nitrogenase) and the removal of headspace acetylene by chemical precipitation to easily scale the ISARA experiment from δ13C to complementary nitrogenase contribution without the uncertainty and tediousness surrounding measurement of the source acetylene.

The new Low activity - ISARA (LISARA) method can now estimate contribution of complementary nitrogenase from environmental samples with as little as 10 ppm of ethylene. Updated limit of quantification for δ13C of ethylene is < 2 ppm. Finally, we demonstrate the applicability of the method using samples with characteristically low N2 fixation activity (termites, wood, leaf litter, soil, moss), with substantial contribution of complementary nitrogenase across multiple sites in the northeastern United States.

Our results expand our knowledge of the contribution of complementary nitrogenase to temperate ecosystems. The new methodology will allow broader access to the classical ISARA method for pure culture experiments and high activity samples through the outsourcing of δ13C ethylene measurements, facilitating the study of complementary nitrogenases.
Atmospheric moisture anomalies associated with ENSO and future changes in CMIP6 simulations
Authors: Watterson Ian
Published: March 2022

Atmospheric moisture is perturbed during ENSO variation, as can be quantified using regression with ENSO indices. Seasonal and annual anomalies of the water column, horizontal moisture flux, surface evaporation, rainfall, and other basic variables, associated with the sea-surface temperature indices NINO34 and Pacific-Indian Dipole are evaluated from ERA5 reanalyses over 1980-2019. The skill in the corresponding regression coefficients (at one standard deviation) from historical climate simulations by the ten (only) CMIP6 models for which the vertically integrated flux was submitted is assessed, subject to the statistical uncertainty in ENSO from 40-year series. The ten-model mean fields are encouragingly realistic, although ENSO anomalies in the equatorial Pacific extend farther westward. The future change for the period 2040-2079 under the SSP585 scenario of rising greenhouse gases is evaluated. There is generally little change in the standard deviation in the two indices or in the SST and wind anomalies. The water column, moisture flux, and rainfall anomalies tend to be amplified in the low latitudes, but with limited change in the teleconnections to higher latitudes. The climatological changes in rainfall and moisture flux resemble those of ENSO in the tropical Indo-Pacific, in part linked to a small positive shift in both the indices. Elsewhere, widespread increases in water column, evaporation, midlatitude surface pressure, and, of course, temperature are not ENSO-like. Implications for the reliability of future projected means and variability will be considered. An obvious recommendation is that the vertically integrated moisture fluxes be routinely output by climate models and be a requested variable in future CMIPs.
Pedestrian Level Greenery Perception quantification
Authors: Meulen Marie , Llaguno-Munitxa Maider
Published: March 2022

The implementation of Nature-based Solutions (NbS) has become a priority in many cities. The benefits of urban demineralization or ‘greening’ initiatives are manifold and range from the mitigation of the urban heat island effect, reduction of flooding risk, to improvements in the outdoor environmental quality. The positive impact on pedestrian level well-being and comfort is also to be taken into account from not only an environmental, but also a visual perspective, given the psychological benefits induced by the attractiveness to nature, and enhanced walkability of streets and squares.

Today, the green infrastructure (GI) evaluation methods utilized in urban planning processes focus on the quantification of the total greenery ratio making use of remote sensing technologies, or often incomplete geospatial databases. The Normalized difference Vegetation Index (NDVI) deduced from aerial imagery, however, does not match the green infrastructure perception at the pedestrian level. From the geospatial databases, on the other hand, tree location and park areas can be retrieved, however these datasets only provide a partial and oversimplified description of the GI. Strategies for the implementation of range in scale and type. Aside from the diverse tree species, cities are populated by diverse grass fields, bushes, and green walls amongst others. Based on the type and distribution of each GI, the impact on the pedestrian level well-being is different. Thus, the quantification of green infrastructure requires the identification of the distinct GI and their distribution evaluated from a pedestrian perspective.  

Our research investigates a novel methodology to quantify the perception of GI from the pedestrian perspective.  We propose to combine NDVI index metrics computed from high-resolution satellite images, with green view index metrics. Making use of a 360° six-lens camera, videos have been collected for 12 different squares selected based on their varied GI ratios and located in the neighborhoods of Saint Gilles and Molenbeek in the city of Brussels. Through Light Detection and Ranging (LiDAR) scanning technologies, point clouds have also been collected for these sites. Once the remote sensing datasets, video recordings, and scans were completed, through geospatial processing and semantic classification, the distinct GI types and ratios were quantified. Our research methodology enables a comparison between remote sensing, geospatial analysis, and first-person quantification of GI computation, and addresses the need of high-res urban environmental analysis for the development of an accurate GI infrastructural evaluation.
Analysis of inundation characteristics under various computational conditions for large-scale flood forecasting
Authors: Koyama Naoki , Yamada Tadashi
Published: March 2022

In recent years, climate change intensifies heavy rainfall, resulting in annual flood damage. Population is increasing worldwide, and urbanization is expected to continue expanding. Under these circumstances, once an inundation occurs, the damage is expected to be more extensive than ever before. Therefore, in this study, we are analyzing the effects of DEM resolution and land use data, which are the calculation conditions for inundation calculations in flood forecasting, on inundation characteristics such as inundation magnitude and duration during large-scale inundation.

　In this paper, the target watershed was the Tone River in Japan, where major floods have occurred in the past, and the analysis was conducted in the plain area. DEM data and land use data are important factors in determining inundation characteristics; The higher the resolution of the DEM data, the better it can represent the microtopography, which in turn affects the inundation flow. Also, land use data determines the roughness coefficient, which affects the velocity of floodwaters, and the infiltration capacity and initial loss into the ground. In this paper, The DEM data were analyzed with resolutions of 5m, 25m, 50, 100m, and 250m. The land use data for the years 1978, 1987, 1997, 2006 and 2016 were used to analyze the inundation characteristics due to increasing urbanization.

The results of inundation analysis with different resolutions of DEM data show that the resolution has no significant effect on the inundation rate. However, as for the inundation area, the larger the mesh size, the larger the inundation area, which is expected to be caused by the homogenization of DEM data. It was also found that as urbanization progresses, the inundation area spreads faster. In addition, the urbanization process affects the diminishing period of inundation rather than the expansion process, because it loses the function of infiltration capacity, and the inundation depth is less likely to decrease.
Doppler shifts of spectral lines formed in the solar transition region and corona
Authors: Chen Yajie , Peter Hardi , Przybylski Damien , Tian Hui , Zhang Jiale
Published: March 2022

Emission lines formed in the transition region and corona show dominantly redshifts and blueshifts, respectively. We investigate the Doppler shifts in a 3D radiation magnetohydrodynamic (MHD) model of the quiet Sun and compare these to observed properties. We concentrate on Si IV 1394 Å originating in the transition region and examine the Doppler shifts of several other spectral lines at different formation temperatures. We construct a radiation MHD model extending from the upper convection zone to the lower corona using the MURaM code. In this quiet Sun model the magnetic field is self-consistently maintained by the action of a small-scale dynamo alone. We synthesize the profiles of several optically thin emission lines, formed at temperatures from the transition region into the corona. We investigate the spatial structure and coverage of red- and blueshifts and how this changes with line-formation temperature. The model successfully reproduces the observed change of average net Doppler shifts from red- to blueshifted from the transition region into the corona. In particular, the model shows a clear imbalance of area coverage of red- vs. blueshifts in the transition region of ca. 80% to 20%, even though it is even a bit larger on the real Sun. We isolate that (at least) four processes generate the systematic Doppler shifts in our model, including pressure enhancement in the transition region, transition region brightenings unrelated to coronal emission, boundaries between cold and hot plasma, and siphon-type flows. We show that there is not the single process that is responsible for the observed net Doppler shifts in the transition region and corona. Because current 3D MHD models do not yet fully capture the evolution of spicules, one of the key ingredients of the chromosphere, most probably these have still to be added to the list of processes responsible for the persistent Doppler shifts.
Vulnerability of peatland complexes in the Hudson Plains, Canada to permafrost-thaw-driven hydrological change
Authors: Mack Mikhail , Quinton William , McLaughlin James , Hopkinson Christopher
Published: March 2022

Thawing discontinuous permafrost in subarctic peatland-dominated landscapes is increasingly recognized as an indicator of a warming climate and potentially shifting these landscapes from atmospheric carbon store to source. Furthermore, in certain discontinuous permafrost landscapes (e.g., northwest Canada) the thaw of permafrost peatlands leads to a reorganization of near-surface flow paths as permafrost-free peatlands expand, connect, merge, and drain. Collectively, these permafrost-thaw-driven landcover and hydrological changes have increased runoff and altered biogeochemical cycles threatening natural resources and critical infrastructure in Indigenous peoples’ traditional territories along with aquatic and terrestrial wildlife habitat. Owing to the region’s remote position and vast scale, comparatively less is known about the landcover and hydrological impacts of permafrost thaw in the Hudson Plains, the world’s third largest peatland region (370,000 km2) and southern most extent continental permafrost. For this study, we assign specific hydrological functions to individual peatland types based on their form, to then infer hydrological flux and storage processes within and between peatlands un a circuitry analog, at the scale of the peatland complexes and peatland complex regions. We analyze several remotely sensed data, including high-resolution lidar, historical air photographs, and recent panchromatic and multispectral satellite imagery along a latitudinal transect to evaluate peatland form, complex, and regional patterns. We then summarise these results and interpretation to present an initial vulnerability map of peatland complexes in the Hudson Plains to permafrost-thaw-driven hydrological change.  
Classification of Boreal Summer East Asian Marine Heatwaves and Their Possible Mechanisms
Authors: Oh Hyoeun , Kim Go-Un , Jang Chan Joo , Jeong Jin-Yong
Published: March 2022

Marine heatwave (MHW) is one of the severe extreme events under global warming, which affects the marine ecosystem and its relevant socio-economic losses. In particular, East Asian sea surface temperature is projected to increase more under the future climate change scenarios than any other ocean worldwide. According to concern for the increasing SST over East Asia, studies on the MHW are needed to minimize the damage. Thus, this study will classify the different spatiotemporal characteristics of East Asian MHWs and find their possible mechanisms using a self-organizing map. There are four dominant modes of MHWs over East Asia: (1) Global warming-like mode, (2) East China Sea mode, (3) East Sea/Japan Sea mode, and (4) Yellow Sea mode. We found the enhanced net downward shortwave radiation plays a crucial role in modulating the onset of the MHW everywhere over East Asia. When looking at the process of MHW occurrence, the spatial patterns related to the Yellow Sea mode and the East Sea/Japan Sea mode appear very similar, but the significant difference between the two modes is the presence or absence of preceding Indian monsoon heating. This means the Indian monsoon heating can precursor the MHWs over the East Sea/Japan Sea. As a result, this study has a significant implication for the predictability of the MHW over East Asia by finding precursors of the MHWs.
Diverse Arctic Oscillation responses after volcanic eruptions at different latitudes during the last millennium
Authors: Paik Seungmok , Min Seung-Ki , Son Seok-Woo , An Soon-Il , Kug Jong-Seong , Yeh Sang-Wook
Published: March 2022

This study conducted a comprehensive analysis of climate responses to volcanic eruptions occurred at different latitudes considering the last millennium volcanic eruptions available from Community Earth System Model ensemble simulations. Especially, we examine how different eruption latitudes induce the different responses in Arctic Oscillation (AO) with polar vortex and thereby exert different influences on northern Eurasian climate. We classify volcanic eruptions as tropical, northern and southern eruptions based on hemispheric aerosol loading ratios, which have different meridional structure of solar radiation perturbations and cause asymmetric climate response patterns between hemispheres, including tropospheric cooling and lower stratospheric warming. Volcanic eruptions found to cause stronger stratospheric polar vortex in both hemispheres with varying magnitudes depending on eruption latitudes. Following the tropical and southern eruptions, polar vortex enhancement is found in both hemispheric polar regions due to enhanced pole-to-equator temperature gradient and equatorward propagation of planetary waves. As a result of boreal winter averaged polar vortex enhancement, the tropical and southern eruptions found to cause more probability to occur at least the pentad strong polar vortex events during the boreal winter, which leads tropospheric westerly wind anomalies after a few days to the events. As a result, positive AO-like responses emerge at the lower troposphere. The positive AO induces surface air temperature warming as well as precipitation increase over the northern Eurasian continental regions. Following southern eruptions, the AO, Eurasian warming and wetting responses are much more extended to more southward (NH mid-latitudes) due to the more equatorward extended polar vortex variation. On the other hand, the Arctic polar vortex and the associated surface responses are only weakly influenced by the northern eruptions, in line with much poleward spread of volcanic aerosols and lesser equatorward extended planetary wave propagation in the lower stratosphere. These results suggest that while volcanic eruptions modulate surface climate by strengthening the polar vortex, their impacts are dependent on the eruption latitudes.
Impact of Self-Calibrating on the Effective Drought Index: A Case Study of the south Korean Peninsula
Authors: Park Chang-Kyun , Kam Jonghun
Published: March 2022

Effective Drought Index (EDI) was proposed to monitor daily propagations of an emerging drought. The EDI, like other drought indices, uses the last 30 years of the daily precipitation record for the reference period for effective precipitation (EP) climatology, resulting that the drought characteristics can be solely estimated by a recent climatology. To overcome this weakness, this study proposes a self-calibrating EDI, a modified EDI with time-varying EP climatology via the 30-year moving time windows. In this study, the scEDI is calculated from the 240-year daily precipitation records (1777–2020) in Seoul, the south Korean Peninsula, and is compared with and the EDIs with different reference periods. The scEDI successfully adapts multi-decadal variability of precipitation, leading to robust (temporally consistent) estimates of drought severity while the EDIs, particularly with the 1885–1915 (dry) and 1990–2020 (wet) reference periods, over- and under-estimate drought severity, respectively. Furthermore, the droughts estimated by the scEDI are compared with the drought damage records in the Annals of the Joseon Dynasty (1778–1907) and the recent search frequency about droughts in Google and NAVER portals (2016–18) to investigate scEDI threshold values that is linked to actual socioeconomic impacts or favorable drought stages for a high level of drought awareness. Results confirmed that -1.0  and -2.0 of the scEDI can be good threshold values to detect severe droughts that cause socioeconomic impacts for agrarian and industrial societies, respectively. It is also found that the persistent and recovery stage of recent droughts surged the Internet search activities while public interest in drought was low during the onset stage. The findings of this study suggest that the importance of self-calibrating on improving the EDI-based drought assessment.
Investigation of added values in multi-model and multi-variable bias adjustments for heat stress assessment
Authors: Kelkar Saurabh , Dairaku Koji
Published: March 2022

Regional climate models (RCMs) are widely used to dynamically downscale the general circulation models (GCMs). Downscaled products can provide a clearer understanding of atmospheric processes compared to the parent models. However, several uncertainties are associated with downscaling, such as structural differences in climate models and biases in GCMs and RCMs. Post-processing methods such as univariate bias correction have been widely used to reduce the bias in the individual variable. However, these methods are applied to variables independently without considering the inter-variable dependence. In compound events such as heat stress, multiple drivers, surface air temperature (SAT), and relative humidity (RH) play crucial roles. Therefore, a multi-variable bias adjustment is necessary to retain the interdependence between the drivers for reliable information on heat stress. The present study focuses on a Multi-variable Bias Adjustment (MBA) method adapted from a topographical adjustment of SAT and RH and its impact on added values in a multi-model ensemble. We investigated added values and biases before and after adjusting the variables. There are gains and losses throughout the process of bias adjustment. Some added values show pseudo nature over some regions after the bias adjustment. Overall, the bias adjustment shows improvement in reducing bias over low-altitude urban areas, encouraging its application to assess heat stress.
Oscillations induced by crack growth in compression and morphology of fracture surface
Authors: Jeffcoat-Sacco Broadus , Dyskin Arcady , Pasternak Elena , Dight Phil , Wang Hongyu
Published: March 2022

Growth of internal cracks in compression is a primary mechanism of catastrophic rock failures.  Since the cracks are internal, only indirect methods are currently available for investigation and monitoring of failures of this kind.  In order to understand the fundamentals of 3D (internal) crack growth in compression, special physical models using transparent polymer prisms with embedded penny-shaped flaws were performed.  A biaxial stress field was applied, to simulate conditions near the face or walls of deep tunnels.  Previously, such experiments were conducted within a fully-enclosed polyaxial testing machine, preventing observation of the growing crack itself.  Recent experiments at UWA utilized a plane-strain restraint device, which develops the secondary principal stress (σ2) by limiting the lateral expansion that would otherwise result from the imposition of the primary principal stress (σ1).  This device leaves clear line-of-sight to the sample free face, allowing visual observation and the installation of other instrumentation. 

As expected, the biaxial stress field resulted in growth of an extensive, nearly planar crack, parallel to the σ1-σ2 plane.  Growth of this crack was observed using high-speed video.  The crack surface morphology shows similarity to many natural and excavation-induced fractures in geomaterials.  This similarity justifies the usage of the transparent materials for investigating rock failure. Furthermore, the observed morphological features can be linked to specific events in the crack growth process.

In addition, experiments incorporated acoustic emission sensors, both on the sample, and in the air near the sample.  Two categories of vibration were observed at the sample’s rear free face: a short-duration wavelet, representing the crack initiation, and a long-duration high-amplitude “ringing” waveform.  The “ringing” was also observed in air (as audible sound) and in video (as movement of the whole sample). The observed vibrations could be utilized for monitoring dangerous rock failures.
Comparison of soil hydraulic properties determined from multiple Earth observation datasets
Authors: Sarma Damini , Gupta Manika , Thomas Juby , Srivastava Prashant
Published: March 2022

Soil properties play an inevitable role in hydrological modelling and there by affecting the quantification of energy and water fluxes both regionally and locally. However, estimating soil properties through field experiments is still a challenge and the literature values do not represent the regional or local areas. The Earth observation datasets can provide the soil surface information. However, the current datasets are at coarse resolution and cannot be utilized for field level agriculture. This study inversely derives the soil hydraulic properties at 30 m resolution by downscaling various microwave Earth observation datasets. The downscaling of soil moisture is achieved with utilization of LANDSAT land surface temperature and normalized difference vegetation index. This product will help in better estimation of hydrological fluxes and also soil management for various hydrological applications and site-specific studies. The accuracy of the algorithm used in the present study is validated at the test site. The method proposed in this study can be implemented in regions where in-situ acquisition of soil properties is not feasible.
Topography and hydro-geomorphic fluxes drive the assemblage of microbial communities
Authors: Ciampalini Rossano , Spor Aymé , Quiquerez Amélie , Philippot Laurent , Bru David , Mounier Arnaud , Follain Stéphane
Published: March 2022

Abiotic factors have long been recognised as important factors in structuring microbial diversity and species associations, among which topography and hydro-geomorphic flows have an impact from plot to large scale. These factors are deeply involved in the dynamics of climate change. However, the actual impact of topography on microbial communities in spatially defined habitats remains unclear and, needing further development, represents a promising branch to investigate microbiological assets in the environment. In this study, we analysed a parcel in continental France which revealed a combined action of hydro-geomorphic fluxes and topography in structuring microbial assemblages. Species-habitat occurrence seems to respond to the effective energy locally displayed by fluxes. Largest richness and microbial variety occurred where fluxes are small such as on limited slope or reduced runoff concentrations. Species dominance was higher in zones with higher fluxes suggesting: 1) an impoverishment of the more sensible species, or 2) a selective adaptation of the most resistant species. This differentiation was evidenced by analysing the potential impact of topography and cumulated fluxes for runoff and sediments (i.e., WTI, LS RUSLE indexes) on microbial richness, dominance, and abondance at Phylum and Class levels.
Assessing of the accuracy of interpolation methods to map soil properties at regional scale in Extremadura (SW Spain)
Authors: Barrena González Jesús , Gabourel Anthony , Lavado Contador J. Francisco
Published: March 2022

Identifying the most appropriate interpolation method for a given area is a necessary step to properly map soil properties. The aim of this work was to evaluate the accuracy and usefulness of 9 interpolation methods (deterministic and geostatistical) with data of 12 soil properties: clay, silt, and sand content, pH, cation exchange capacity, and calcium, magnesium, sodium, nitrogen, phosphorus, potassium and organic matter content, that were measured at three different depth ranges, i.e., 0-5 cm, 5-10 cm and > 10 cm. Data gathered from more than 400 sampling points were used to map these soil properties in the Spanish region of Extremadura (ca. 41,000 km2 of land surface). Data showed a high variability, both in terms of the different parameters and the depth intervals. The coefficient of determination (r2) and root mean square error (RMSE) were used as statistics to determine the accuracy and decide the most suitable interpolation method in each case. The results were variable, and the most appropriate interpolation method varied according to the property of the soil and the depth under consideration. As some instances, for the 0-5 cm clay content data the best method was the ordinary kriging (0.714 r2 and 3.629 RMSE), while for the 5-10 cm data Spline with Tension (0.56 r2 and 5.855 RMSE) produced better results. In the case of pH values, however, the Completely Regularized Spline method yielded good results both for depths of 0-5 cm (0.678 r2 and 0.487 RMSE) and 5-10 cm (0.610 r2 and 0.603 RMSE), being preferable the ordinary kriging to the depths > 10 cm (0.667 r2 and 0.639 RMSE). In general, it was the Inverse Distance Weighting (IDW) method which showed the best results, followed by other deterministic methods such as Completely Regularized Spline (CRS) and Spline with Tension (SwT). Furthermore, Empirical Bayesian Kriging (EBK) was the geostatistical method that yielded the best results.  In view of the results obtained, the need to consider various interpolation methods when mapping soil properties becomes evident.